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HomeMy WebLinkAboutAgenda Packet - 2014-12-01STAFF REPORT CITY OF LAKE OSWEGO PLANNING DIVISION APPLICANT: Silver Oak Custom Homes OWNERS: David and Debbie Craig TAX LOT REFERENCE: Tax Lots 5200, 5201, 5300, 5400, and 5401 of Map 2 1E 10DC 850 Cedar Street COMP. PLAN DESCRIPTION: R-7.5 ZONING DESIGNATION: R-7.5 FILE NO: LU 14-0046 STAFF: Jessica Numanoglu DATE OF REPORT: November 6, 2014 DATE OF HEARING: November 17, 2014 120 -DAY DECISION DATE: February 19, 2015 NEIGHBORHOOD ASSOCIATION: Hallinan Heights I. APPLICANT'S REQUEST The applicant is requesting approval of the following: • Delineation of a Resource Protection District (stream corridor); • An 8 -lot subdivision (all lots are considered flag lots); and, • Removal of 13 trees. II. RECOMMENDATION Approval of LU 14-0046 with conditions. The complete listing of conditions is provided on pages 25- 32 of this report. LU 14-0046 Page 1 of 33 IV. APPLICABLE REGULATIONS A. City of Lake Oswego Community Development Code (LOC Chapter 50): LO C. LOC 50.04.001.1 LOC 50.05.010; 50.07.004.8 LOC 50.06.002 LOC 50.06.003.1 LOC 50.06.003.2 LOC 50.06.003.3 LOC 50.06.003.4; 50.07.004.5 LOC 50.06.003.5 LOC 50.06.004.1 LOC 50.06.004.2; 50.07.004.2 LOC 50.06.004.3 LOC 50.06.005; 50.07.004.7 LOC 50.06.006.1; 50.07.004.10 LOC 50.06.006.2; 50.07.004.3 LOC 50.06.006.3.b; 50.07.004.1 LOC 57.06.007; 50.07.004.9 LOC 50.06.008; 50.07.004.11 LOC 50.07.003.1 LOC 50.07.003.5 LOC 50.07.003.6 LOC 50.07.003.10 LOC 50.07.003.14 LOC 50.07.007.2 Residential Low Density Zones Dimensional Standards Sensitive Lands Overlay Districts Parking Access/Access Lanes (Flag Lots) On-site Circulation — Driveways and Fire Access Roads On-site Circulation — Bikeways, Walkway and Accessways Local Street Connectivity Transit Landscaping, Screening and Buffering Fences Lighting Standard Park and Open Space Contributions Weak Foundation Soils Hillside Protection Drainage Standard (Subdivisions) Solar Access Utilities Application Procedures Conditions on Development Effect of Decision Certificate of Occupancy Minor Development Decisions Flag Lots City of Lake Oswego Streets and Sidewalks Code [LOC Chapter 421: LOC 42.08.400 - 42.08.470 Streets and Sidewalks City of Lake Oswego Tree Code [LOC Chapter 55]: LOC 55.02.010 - 55.02.080 LOC 55.02.084 LOC 55.08.020 LOC 55.08.030 FINDINGS A. Background/Existing Conditions: Tree Removal Mitigation Requirements Tree Protection Plan Required Tree Protection Measures Required 1. The site is 2.09 acres in size and is located at the end of Cedar Street, a local street (Exhibit E1). The Cedar Street right-of-way extends into the site off the end of the cul-de-sac and contains a public waterline. The applicant intends to submit a request to the City to vacate this portion of the Cedar Street right-of-way and to relocate the public waterline. If approved by the City Council, the street vacation would increase the size of the site to 2.189 acres. Because the proposed subdivision is contingent on the right-of-way dedication, LU 14-0046 Page 2 of 33 approval of the street dedication would be required as a condition of approval prior to recording the final subdivision plat. The site is zoned R-7.5 and is developed with a single-family dwelling and accessory structures (Exhibits E3 and E6). The applicant will demolish all the accessory structures on the site, but wants to retain the option of either demolishing the existing dwelling or moving it onto one or more of the newly created lots prior to site development (Exhibit F8). Properties to the north, east and west are also zoned R-7.5 and most are developed with single-family dwellings. The property abuts Freepons Park to the south, which is zoned PNA (Park and Natural Area). 3. On the east side of the site there is a mapped RP District and a conservation easement that was dedicated to the City in 1997 (Exhibit E3). 4. According to the City Soils Map, the site is in an area that may contain weak foundation soils. The site slopes down steeply along the north and northeast sides of the site. There is a landslide that occurred in the northwest area of the site which was repaired in 1987 (Exhibit E10). There are approximately 112 trees that are five inches in diameter or greater on the site (Exhibit E9). V. PUBLIC NOTICE OF APPLICATION AND APPLICANTS' BURDEN OF PROOF A. Neighborhood Meeting: A neighborhood meeting was held on June 4, 2014, to satisfy the requirements of LOC 50.07.003.1.f (Exhibit F2). LU 14-0046 Page 3 of 33 B. Public Notice to Surrounding Area: The City has provided adequate public notice and opportunity to comment on this application, as required by LOC 50.07.003.3. No letters were received during the preparation of this report. C. Burden of Proof: Per LOC 50.07.003.1.b, the applicant for a development permit shall bear the burden of proof that the application complies with all applicable review criteria or can be made to comply with applicable criteria by imposition of conditions of approval. The applicant has provided sufficient evidence to enable staff to evaluate the proposal. These documents are listed as exhibits at the end of this report. VI. LOC 50.07.003.14 — MINOR DEVELOPMENT A. Classification of Application: LOC 50.07.003.14.a.ii(9) and (20) designates both a subdivision and RP Delineation as a minor development. B. Criteria for Review of Application: Per LOC 50.07.003.14.d.ii, for any minor development application to be approved, it shall first be established that the proposal complies with: The requirements of the zone in which it is located; Dimensional Standards [LOC 50.041 Residential Low Density Zones [LOC 50.04.001.1] The site is zoned R-7.5. The applicant proposes to divide the site into eight lots to be developed with single-family dwellings at a later time (Exhibit E7). Single-family residential use is permitted in the R-7.5 zone. Maximum Density Maximum density is determined by dividing the net developable acreage (excluding area in public right of way or access easement) by the minimum lot area requirement for the R-7.5 zone (7,500 square feet) and rounding down to the nearest whole number. The total area of the site (95,356 s.f., including the portion of Cedar Street proposed to be vacated) minus the area in access easement (11,253 s.f.) is 84,103 s.f. Dividing 84,103 s.f. by 7,500 s.f. yields a maximum density of 11.21 lots, which is rounded down to 11 lots (Exhibit F1). As Exhibit E7 illustrates, the applicant is proposing eight lots, complying with the limitation of this standard. LU 14-0046 Page 4 of 33 Minimum Density Subdivisions are required to provide a minimum density of 80% of the maximum density allowed by the zone. It is determined by dividing the net developable area by the minimum lot size required in the zone and multiplying this number by 0.8. The result is rounded up for any product with a fraction of 0.5 or greater and rounded down for any product with a fraction of less than 0.5. The number of lots required by the minimum density provisions may be reduced as necessary where natural resource constraints exist on site to the extent that the minimum number of lots could not be developed (LOC 50.04.003.10.c.iv). There is a delineated RP District on the east portion of the site that occupies a total area of 10,346 s.f. (Exhibits E3 and F1). Subtracting the resource area from the net developable area, dividing the result by 7,500 s.f. and multiplying it by 0.8 yields a minimum density of 7.87 lots, which is rounded up to eight lots. The applicant's proposal for eight lots satisfies this requirement. Lot Dimensions and Site Development Limitations The minimum lot size requirement is 7,500 square feet and the minimum lot width is 50 feet. Because all of the proposed lots are flag lots, the area of access easement is deducted from the gross lot area (LOC 50.07.007.2.d.iii). Exhibit E7 illustrates that the proposed lots range in size from 7,500 to 10,491 square feet, excluding area in access easements, and that all of the proposed lots exceed the minimum 50 -foot lot width requirement. This standard is met. The maximum height and minimum setbacks of the R-7.5 zone are superseded by the Flag Lot standard (LOC 50.07.007.2.e. iii and v), which is discussed in more detail later in this report. The applicant shall note that for the purpose of measuring building height for future structures on each lot, the height is measured from existing grade where fill is proposed (see definition of "Height of Building" in LOC 50.10.003.2). The applicant will be required to illustrate the existing grade prior to the grading for the proposed subdivision on the building plans submitted for each lot. Compliance with the site development limitations will be assured at the time of building permit application on each lot, including if the applicant elects to move the existing dwelling on the site to one or more of the newly created lots. Land Divisions [LOC 50.07.0071 Flag Lots [LOC 50.07.007.21 All eight lots are being created through the requirements of the Flag Lot section. Flag lots are regulated by the applicable criteria of the underlying zone, as well as additional specific requirements of LOC 50.07.007.2. The applicant's narrative (Exhibit F1) has addressed the specific requirements of this section of the Code. LOC 50.07.007.2.a.iv — Parcelization In addition to the general application requirements for land divisions, an application to create a flag lot shall include a conceptual plan of complete parcelization of the subject property. The reviewing authority may impose conditions in order to ensure that parcelization of the subject property will not preclude the development of surrounding LU 14-0046 Page 5 of 33 properties. Such conditions may be related (but not limited) to access, circulation, building location, utility availability, and natural resource protection. The proposed 8 -lot subdivision represents the full parcelization of the site (Exhibit E7). Staff finds that because the properties surrounding the site are either park land or fully developed single- family lots, this standard is met with no conditions of approval necessary. LOC 50.07.007.2.c — Access Street frontage for a flag lot is not required but access to a public or private street is. LOC 50.07.007.2.c.i and ii specifies that access be consolidated where practicable, including consolidation with the parent lot. Access lanes shall be extended to abutting developable property to provide a continuous connecting access lane where practicable. As illustrated on Exhibit E7, all eight flag lots will be accessed by one private access lane off the end of Cedar Street. Because the site is surrounded by park land and fully developed single-family lots, it is not practicable to extend the access lane to any of the abutting properties (Exhibits E1 and E4). LOC 50.07.007.1.c.iii(1) requires that an access lane serving a flag lot be paved a minimum of 12 feet in width. The proposed access easement and pavement width varies from 20 to 26 feet (Exhibit E7) in compliance with this standard. Per LOC 50.07.007.1.c.iv, no more than two driveways are permitted within 50 feet of one another as measured from the closest edge of each driveway. As noted above, the shared access lane (driveway) provides access for all eight lots (Exhibit E7). There is one driveway on the lot abutting the site in the northwest corner that is within 50 feet of the access lane, but there are no more than two driveways within 50 feet of one another as required by this standard (Exhibit E3). As a condition of approval, the applicant shall post addresses for all eight lots at the beginning of the access lane in compliance with LOC 50.07.007.1.c.v. A joint maintenance agreement for the access lane should be recorded to assure that the shared access is properly maintained. This will be made a condition of approval. As conditioned, this standard is met. LOC 50.07.007.1.d - Lot Configuration Reauirements Per LOC 50.07.007.1.d.i(1), the front yard of a flag lot is determined at the time of lot creation and is measured from the access lane or from a projected extension of the access lane through the property. As illustrated on Exhibit E7, all eight lots have their front yards abutting the access easement. This restriction shall be recorded in a notice of development restriction. As conditioned, this standard is met. LOC 50.07.007.1.e - Building Site and Desien Standards LOC 50.07.007.1.e prescribes building orientation, garage placement, height, setbacks, and lot width requirements for flag lots. Building orientation should provide the maximum separation and privacy from existing and future dwellings on adjacent lots. As shown on Exhibit E7, the front yards of all eight lots abut the access lane and the rear yards are on the north and south sides of the lots. There is an open space tract on the east side of the site that provides ample separation between the proposed lots and the abutting lots to the east and only Lot 1 has a 10 -foot side yard LU 14-0046 Page 6 of 33 adjacent to three lots to the west. However, with the exception of an 18 -foot section of one lot that abuts the southwest corner of Lot 1, the abutting other two lots are owned by the applicant (Exhibit E14). Staff finds that the yard orientation provides the maximum potential separation from the buildable area on the flag lots and the existing dwellings on lots at the perimeter of the site. Garages must either be side -loading or located such that no more than 40 percent of the garage wall area is visible from the intersection of the flag lot driveway and street, or if it is visible, it shall have more than one plane. Although no building plans have been submitted for the lots, the proposed building envelopes are large enough to allow a garage design to comply with the garage placement requirements of this standard. Compliance with this standard will be assured during the building permit approval process. Flag lot height requirements prescribe that structures on the flag lot should not exceed either the average height of all dwellings on properties abutting the development site or 22 feet, whichever is taller [LOC 50.07.007.1.e.iii(1)]. There are eleven lots abutting the project site with an average height of 21.8 feet (Exhibits E5 and F1). Because the average height is less than 22 feet, the maximum permitted height of structures on all lots shall be 22 feet as measured for a "lot with sloping topography". Exceptions to the maximum height for roof forms and architectural features are permitted in compliance with LOC 50.07.007.1.e.iii(4). The 22 -foot height restriction for a lot with sloping topography should be included as the maximum height allowed on all the lots in the notice of development restriction to be recorded along with the final plat. As noted under the zone dimensional standards above, for the purpose of measuring building height for future structures on each lot, the height is measured from existing grade where fill is proposed (see definition of "Height of Building" in LOC 50.10.003.2). The standard front, side and rear yard setbacks of the R-7.5 zone are superseded by the yard setbacks as outlined per LOC 50.07.007.1.e.v. The side and rear yard setbacks for flag lots are established at the time of flag lot creation. A minimum 10 -foot front yard setback is required from the access lane, except that a 20 -foot setback is required from the access lane to the front of a garage or carport when the garage or carport opening faces the access lane. The sum of the side and rear yard setbacks on flag lots shall be not less than 45 feet in the R-7.5 zone. In applying the flexible setback standard, the yard dimensions should be similar to the yard dimensions of primary structures on properties that abut the rear or side yards of the flag lots, but in no case shall a rear or side yard setback be less than 10 feet. Exhibit E7 illustrates that 10 -foot front yard setbacks for the dwelling and 20 -foot front yard setbacks for the garage will be provided from the access lane on all eight lots. The side yard setbacks on all the lots are proposed to be 10 feet or more and the rear yard setbacks on Lots 1-4 and 6-7 are proposed to be 25 feet. Lots 5 and 8 are proposed to have 16 -foot and 10 -foot rear yards, respectively; however, as shown on Exhibit E7, because both of these lots are proposed to have larger side yard setbacks ranging from 19-26 feet, the rear and side yards add up to 45 feet or more in total. In addition, staff notes that the rear yard of Lot 5 abuts the park and the portion of the rear yard of Lot 8 that is proposed to have a 10 -foot setback is limited to approximately 37 feet long due to the presence of a 14 -foot wide storm drainage easement in the rear yard. The setbacks shall be included in the notice of development restriction to be recorded along with the final subdivision plat. LU 14-0046 Page 7 of 33 The lot width dimension of a flag lot shall be not less than the minimum 50 -foot lot width required in the R-7.5 zone. All eight lots have lot widths that exceed 50 feet (Exhibit E7). As conditioned, this standard is met. LOC 50.07.007.1.f - Screening, Buffering, and Landscape Installation Per LOC 50.07.007.1.f.i, a minimum 5 -foot landscape buffer should be provided on either side of an access lane. The buffer must be planted with trees and shrubs which will provide an effective screen within two years of planting. Where land area is not sufficient to accommodate a 5 -foot wide landscape strip on either side of the access lane, the reviewing authority may impose conditions of approval to include measures that will provide effective buffering and screening. These measures may include landscaped islands, fencing, and meandering access lane. As illustrated on the landscape plan (Exhibit E14), a 5 -foot landscape buffer is proposed along either side of the access lane, except along the west side of the access lane from the entrance to the site to the northern edge of Lot 1. Due to the site's limited frontage on Cedar Street and the need to design the access lane to meet fire lane requirements for width and turning radius, there is not sufficient area on the west side of the access lane to accommodate a landscape buffer. As a condition of approval, the applicant should be required to install a 6 -foot tall sight -obscuring fence on the west side of the access lane extending from the entrance to the site to the northern edge of Lot 1. As an alternative to the fence, the applicant may elect to install a 5 -foot landscape buffer along the east property line of the abutting lot to the west (Tax Lot 5101), which is also owned by the applicant. Maintenance of the landscape buffer is an ongoing obligation of the property owner(s). LOC 50.07.007.1.f.iii requires the rear and side yards of the flag lot to be screened from the abutting properties with a 6 -foot tall fence, except where the abutting property owners agree in writing that a fence is not necessary along the common property line. Additionally, a minimum 6 -foot wide landscaped buffer should be planted along the rear property line of all the lots. The landscape buffer may also be waived where the abutting property owners agree in writing that the buffer is not necessary. Existing landscaping may be incorporated in the 6 -foot landscape buffer plan as long as it will provide effective buffering and screening to mitigate visual impacts. The fence and landscaping requirements do not apply to side or rear yards that are interior to the subdivision or to side or rear yards that abut lots under the applicant's ownership outside the subdivision site. As illustrated on Exhibit E14, a 6 -foot fence and 5 -foot landscape buffer are proposed along the rear yards of Lots 6- 8 and a 6 -foot fence is proposed along an approximately 18 -foot portion of the side yard of Lot 1 abutting a lot that is not under the ownership of the applicant to the west. No other fencing or landscaping is required for the rear or side yards of the other lots. This standard is met. When tree removal is proposed on a flag lot, evergreen or deciduous tree shall be planted at a minimum 1:1 ratio where practicable in order to mitigate their removal. The mitigation trees are required to be of a species that will attain a minimum of 30 ft. in height. Deciduous trees shall be a minimum of two -in. caliper and evergreen trees shall be a minimum of eight ft. tall at the time of planting. As illustrated on Exhibit E9, a total of 13 trees are proposed to be removed from the flag lots in order to grade the site and construct the access lane and utility improvements. LU 14-0046 Page 8 of 33 Thirteen two-inch caliper big leaf maples are proposed to mitigate for the tree removal. Big leaf maple obtain a mature height of greater than 30 feet. This standard is met. Staff finds that, as conditioned, the proposed flag lots can be made to comply with the requirements of this article. Overlay and Design Districts ROC 50.051 Sensitive Lands Overlay Districts [50.05.010] The purpose of the Sensitive Lands districts, as designated on the City's Sensitive Lands Atlas, is to protect the functions and values of wetlands, stream corridors, and tree groves on lands with environmental or natural significance. According to the City's Sensitive Lands Atlas, there is a stream corridor on the east portion of the site that is designated as Class II RP District. Delineation of Resource [LOC 50.07.004.8.dl A stream corridor boundary shall be measured or delineated based on topographic maps, hydrology maps, and/or field observations, pursuant to Figure 50.07.004-A: Wetland and Stream Corridor Measurement. Figure 50.07.004-A illustrates that a stream corridor boundary is generally located either at the top of bank or 10 feet from the stream centerline, whichever is greater. The top of bank is defined as the intersection of flat land and the slope of the bank. The stream corridor on the site is bifurcated because the middle portion enters a culvert and is piped for approximately 160 feet (Exhibit E3). The stream channels on both ends of the pipe are narrow and the adjacent topography is relatively flat, therefore the stream corridor boundary is located 10 feet from the stream centerline as illustrated on Exhibit E3. The City's Natural Resource Planner reviewed the delineation and concurs with the stream corridor boundary as delineated by the applicant's resource professional. Protected Riparian Area and Construction Setback [LOC 50.05.010.6.bl For Class II stream corridors the RP District shall include the delineated stream and a 25 - foot protected riparian area. In addition, a 10 -foot construction setback from the RP LU 14-0046 Page 9 of 33 District is required for new structures, parking areas, active use recreation facilities, streets and driveways. As illustrated on Exhibit E3, the RP District includes a 25 -foot protected riparian area and the 10 -foot construction setback is provided from the RP district. The entire RP District is located within the proposed open space tract on the site, which will be maintained by the homeowners association. The applicant will be required to include a map illustrating the delineated RP District and 10 -foot construction setback in a notice of development restriction. This standard is met. RP District Develooment Standards FLOC 50.05.010.6.c All new lots or reconfigured lots proposed on lands that include an RP District shall have designated sites for buildings that are located outside of the RP District. As illustrated on Exhibit E7, the delineated RP district is located entirely within the open space tract for the subdivision and does not extend on to any of the lots. A portion of the existing asphalt driveway on the site is located in the RP District (Exhibit E3). The applicant proposes to remove the driveway and plant the disturbed area with native vegetation (Exhibits E6 and E14). Per LOC 50.05.010.6.c.ii(1)(a), landscaping with plants on the City's Native Plant list is permitted within the RP District. The applicant proposes a soft surface pathway within the RP District to provide residents access to Freepons Park to the south of the site (Exhibit E14). Pursuant to LOC 50.05.010.6.c.ii(1)(e)(i)(C), passive use recreation facilities, such as soft surface trails and pedestrian bridges, are permitted within the RP District. Some grading is proposed within the RP District in order to construct the path (Exhibit E10). The disturbed area within the RP District on either side of the path will be required to be replanted with native vegetation after construction of the path. The applicant shall submit a revised landscape plan prepared by a qualified resource professional showing the location, size and species of plant materials to mitigate the disturbed areas within the RP District that are necessary to construct the path. A Mitigation, Monitoring, and Maintenance Plan is also required to be submitted in accordance with LOC 50.05.010.4.g.i(2). The Mitigation, Monitoring, and Maintenance Plan shall state that plant materials will be replaced as needed throughout the monitoring period to ensure an 80% survival rate, and invasive plants will be removed to ensure less than 5% cover of invasive species. It should also state that any replacement species must be approved by the City, and that the applicant or other legally responsible agent shall provide an annual report to the City Manager by October 31 of each year for a three-year period. Per LOC 50.05.010.4.g.viii, the applicant will also be required to submit a performance bond or letter of credit that is equal to 120% of the value of the mitigation prior to the issuance of a building permit. As conditioned, this standard is met. Construction Standards [LOC 50.05.010.4.dl The applicant will be required to install tree and RP District protection fencing around the delineated RP District prior to commencing any construction activities. No stockpiling of fill materials, or parking or storage of construction equipment shall be allowed within the RP District. A condition of approval will be imposed to assure compliance with this standard. LU 14-0046 Page 10 of 33 Staff finds that the applicant has demonstrated compliance with all the applicable Sensitive Lands regulations. The applicable Development Standards [LOC 50.06]; Parking [LOC 50.06.002] This standard requires that a single-family dwelling provide a minimum of one off-street parking space per unit, which shall not be located in a required yard. Exhibit E7 illustrates that all of the lots are large enough to accommodate one or more off-street parking spaces. This standard is met. Access/Access Lanes (Flag Lots) [LOC 50.06.003.1] This standard requires that, except for flag lots, every lot shall abut a public street for a width of at least 25 feet and that the proposed point of access be adequate for the site based on the topography, traffic volume generated by the development, and classification of the public street from which the access is taken. Determination of the location and configuration of an access shall be based on a traffic study, unless otherwise approved by the City Manager. This standard also prescribes standards for the easement and pavement widths of access lanes and requires "on -lane" parking for access to seven or eight dwelling units. All eight lots are flag lots, therefore, frontage on a public street is not required. As illustrated on Exhibit E7, the applicant proposes an access easement over the northeast corner of the abutting lot to the west (Tax Lot 5101) in order to provide access to the site from Cedar Street. Tax Lot 5101 is under the ownership of the applicant. As a condition of approval, the applicant should be required to record the access easement and provide a copy to staff prior to recording the subdivision plat. The Engineering staff has not identified any issues associated with the proposed access point on Cedar Street and did not require a traffic study. A 20 -foot wide easement is required for access lanes and a pavement width of 16 feet with 2 -foot shoulders on each side is required for access lanes serving five to eight dwelling units. Additionally, when providing access for seven to eight dwelling units, the access lane shall be designed to provide "on -lane" parking for a minimum of four standard vehicles or provide an "off -lane" parking area for a minimum of four standard vehicles. Exhibit E7 illustrates that the proposed access lane serving all eight lots has both an easement and pavement width that ranges from 20-26 feet. Four "on -lane" parking spaces are provided on the north side of the access lane (Exhibit E12). This standard is met. On -Site Circulation - Driveways and Fire Access Road [50.06.003.2] This standard contains the geometric design standards for proposed driveways that act as fire department access roads, and other design features such as maximum permissible slope and the width of driveway approaches. All driveway approaches shall be located and designed so that the driver entering or exiting the driveway can see approaching traffic for a sufficient distance to make a safe entrance or exit. The American Association LU 14-0046 Page 11 of 33 of State Highway and Transportation Officials (AASHTO) standards shall be used in determining compliance with this standard. In addition, where a driveway that meets the public street is used by multiple drivers, the landing area shall be a minimum of 25 feet long and shall have a maximum grade of five percent. A private access lane will provide access from the end of the Cedar Street cul-de-sac (Exhibit E12). The applicant has provided a preliminary sight distance and vision clearance triangles plan indicating the sight distance for future driveways on the lots will comply with this standard (Exhibit E11). In addition, the preliminary street profiles drawing (Exhibit E13) shows that the driveway approach and landing at the Cedar Street cul-de-sac will be a minimum of 25 feet long and have a maximum grade of five percent. Exhibit E10, which provides topographic information, illustrates that future driveways on each lot can be constructed within the maximum slope standards prescribed by this standard. All developments shall comply with the minimum requirements for fire access roads as stipulated by the Fire Code and LOC Chapter 15. If a dead-end driveway exceeds 150 feet in length, it shall provide a fire department turnaround in compliance with the City's Standard Details, except that the Fire Marshal may approve driveways greater than 150 feet in length if the structures greater than 150 feet from the public street are provided with alternative methods of fire suppression, i.e., sprinklering. Required turnarounds shall not overlap a required parking space. The applicant has submitted a fire hose plan illustrating that Lots 1 and 8 are within 150 feet of a public street and can be served by emergency vehicles, including a fire truck (Exhibit E8). Lots 2-7 are more than 150 feet from a public street and future structures on these lots are proposed to be provided with automatic fire suppression sprinkler systems. A modified fire department turnaround is proposed at the end of the access lane (Exhibit E16). According to the Fire Marshal (Exhibit F3), emergency vehicle access to the site is adequate as proposed provided automatic fire suppression sprinkler systems are installed in structures on Lots 2-7, and the turnaround, south side of the access lane, and any portion of the access lane that is less than 26 feet in width are marked with "No Parking — Fire Lane" signs. As conditioned, staff finds that the requirements for on-site circulation for driveways and fire access roads can be met. Compliance will be assured during review of the building permit application on each parcel. On Site Circulation — Bikeways, Walkways and Accessways [LOC 50.06.003.3] This section is applicable to subdivisions. Accessways for use by pedestrians and bicyclists shall be required when necessary to provide direct routes not otherwise provided by the existing right-of-way. Developments shall not be required to provide right-of-way for accessways off site to meet this requirement. All lots have access to Cedar Street from the private access lane; only Lots 1-5 have direct access to Freepons Park abutting the site to the south (Exhibit E7). The applicant proposes a residential accessway through the open space tract to provide direct access to Freepons Park for all lots in the subdivision (Exhibit E14). LU 14-0046 Page 12 of 33 A residential accessway shall include at least a 15 -foot wide right-of-way or easement and a minimum 6 -foot wide travel surface. Accessways may meander around major trees or vegetation, but shall be as straight as practicable, considering the circumstances related to the property. The surfacing of residential accessways shall consist of either two inches of asphaltic concrete over a minimum of four inches of compacted crushed rock, or four inches of concrete, as determined by the City Manager. Depending on location, topography or presence of sensitive lands, other materials may be specifically approved by the City Manager. The proposed accessway is a 6 -foot wide pathway contained within a 15 -foot wide easement and is straight as practicable given the shape of the open space tract (Exhibits E7 and E14). Due to the presence of a delineated RP District in the southern portion of the open space tract, the pathway is proposed to be a soft surface rather than concrete. Soft surface pathways are permitted in the RP District per LOC 50.05.010.6.c.ii(e)(i)(C). Staff finds that the proposed residential accessway complies with the standards of this section. Local Street Connectivity [LOC 50.06.003.4] This standard addresses connectivity for automobiles, pedestrians, and cyclists to assure the layout of the local street system does not create excessive travel lengths or limit route choices. This standard applies to any development resulting in the construction of a new street or any land division that is located on a parcel or parcels of redevelopable land of 1.75 acres or more. Development shall be designed so that streets and pedestrian accessways create connections that improve local access to the existing system and consider connections to adjacent developable properties. Local and neighborhood collector streets shall provide for full street connections between through streets with spacing of no more than 530 feet, measured between the centers of the intersection of two through streets that provide for vehicle traffic movement. An exception to this requirement is permitted due to the presence of freeways or existing development patterns on abutting property which preclude the logical connection of streets (LOC 50.06.003.4.c.vi). As illustrated on Exhibits E1 and E4, a street connection to the proposed access lane is not possible on the abutting properties to the north, east and west because they are fully built out and the site abuts a park to the south; therefore, no street connection will be required. LOC 50.06.003.4.c.vii and viii state that if an exception to the street connection is allowed, then a residential accessway on a public easement will be required so that spacing between bicycle and pedestrian connections shall be no more than 330 feet. However, a reduction in the number of residential accessways may be allowed if doing so would not significantly add travel time or distance from the proposed development to bus lines or activity centers in the area, or if existing development patterns on abutting properties preclude a logical connection, or if the traffic impacts from the development are too low to justify the cost of the accessway. Because the site is located at the terminus of Cedar Street and the surrounding properties are fully developed and do not contain a residential accessway to connect to the site, requiring a residential accessway accessible to properties off the site will not reduce travel time or distance from the proposed development to bus lines or activity centers. However, LU 14-0046 Page 13 of 33 because Lots 6-8 within the proposed subdivision do not abut Freepons Park, the travel distance to the park using existing rights-of-way to the west would add significant travel time and distance. As discussed under the On -Site Circulation — Bikeways and Accessways, above, the applicant proposes a residential accessway through the open space tract that would be accessible by all lots in the subdivision. The accessway will provide a direct connection to Freepons Park to the south (Exhibits E7 and E14). Staff finds that proposed development complies with this standard. Transit System [LOC 50.06.003.5] This standard applies to all new subdivisions located on a transit street or within one- quarter of a mile of a transit street and requires the installation of transit facilities and transit -oriented features that connect the development with the nearest transit street or paths that lead to the nearest transit street. The project site is located approximately 800 feet away from McVey Avenue, which is a bus route. The closest bus stop is located at the intersection of McVey Avenue and Cornell Street. There are no paths adjacent to the site that leads to the nearest transit street and no planned paths or sidewalks along Cedar Street. As a result, staff finds that the installation of transit facilities and features is not required. This standard is met. Landscaping, Screening and Buffering [LOC 50.06.004.1] This standard is applicable to subdivisions and requires all development abutting streets to provide street trees at the proper spacing for the species The landscape plan illustrates that street trees will be provided along the access lane frontages of all the lots (Exhibit E14). This standard is met. Fences [LOC 50.06.004.2] This standard applies to any development proposing fences or retaining walls. The maximum height of a fence is six feet, except where a fence is within 10 feet of a property line that abuts a public or private street, in which case the maximum height is four feet. Retaining walls greater than four feet in height, measured from the top of the retaining wall to the top of the footing, must meet setback requirements, except that retaining walls supporting driveways are exempt from setback requirements. As required by the Flag Lot Standard, above, a 6 -foot tall fence is proposed in the rear yards of Lots 6-8 (Exhibit E14). The fence on Lot 8 shall be stepped down to four feet in height within 10 feet of the Cedar Street right-of-way. As conditioned, this standard is met. Lighting Standard [LOC 50.06.004.3] This standard prescribes equipment and lighting standards for public and private streets, pathways, accessways and parking lots, and requires street lights at intersections for local streets. This development will create increased traffic, bike and pedestrian trips to the intersections of Cedar Street / Cornell Street and McVey Avenue / Cornell Street, thus requiring it to mitigate its impact to the transportation system. With the increase in use of LU 14-0046 Page 14 of 33 the site, street lights would be required at these intersections, however because these intersections already have street lights, no additional street lighting will be required. This standard is met. Park and Open Space Contributions [LOC 50.06.005] This standard requires that subdivisions provide at least 20% of the gross land area in open space. The open space shall include areas identified as RP or RC Districts on the Sensitive Lands Atlas. Areas that contain resources identified as Class I or II Riparian Corridors/Wildlife Habitat or Class A or B Upland Wildlife Habitat as mapped on Metro's Title 13 Regionally Significant Fish and Wildlife Habitat Inventory Map shall also be included provided, however, the maximum required area is 20% of the gross site area. Lands selected for open space are to be reserved in accordance with the priorities listed in LOC 50.07.004.7.c. The east side of the site contains an RP District and lands classified as Class I and II Riparian Corridors/Wildlife Habitat on Metro's Title 13 Map. As illustrated on Exhibit E7, a total of 19,129 square feet or 20.1% of the site is provided in an open space tract on the east side of the site. The open space tract includes the area within the RP District as well as most of the riparian corridor/wildlife habitat area identified on Metro's Title 13 Map. Maintenance of private open space tract shall be the common responsibility of the lot owners, which is exercised through a homeowners association. As a condition of approval, the applicant will be required to submit CC&Rs of the homeowners association for review and approval of staff that addresses the ownership, use, and maintenance of open space tract. As conditioned, this standard is met. Weak Foundation Soils [LOC 50.06.006.1] According to the City's Soils Map, the site is located in an area that may contain weak foundation soils. The applicant submitted a geotechnical report (Exhibit F4) from a registered soils engineer that does not indicate the presence of weak foundation soils on the site. As a result, this standard is not applicable. Hillside Protection — [LOC 50.06.006.2] This site is identified as being in a potential slide area on the City's Soils Map. This standard requires that all development on undisturbed slopes be designed to minimize the disturbance of natural topography, vegetation and soils. Development is prohibited where landslides have actually occurred, or where field investigation confirms the existence of a severe landslide hazard; however, the granting authority may allow development in a known or confirmed landslide hazard area if specific findings are made that the specific provisions in the design of the proposed development will prevent landslides or damage. The granting authority may apply any conditions, including limits on type or intensity of land use, which it determines are necessary to assure that landslides or property damage will not occur. As illustrated on the preliminary grading plan (Exhibit E10), the development on the site is occurring in areas with existing development and/or previously modified slopes. A LU 14-0046 Page 15 of 33 landslide occurred in the northern portion of the site, which was repaired with a retaining wall and fill in 1987 (Exhibit E10). As recommended in the geotechnical report submitted by the applicant, the "undocumented fill" that was placed in the landslide area will be removed and the existing public waterline in the area of the landslide will be relocated (Exhibits E10 and F4 -F6). According to the applicant's geotechnical engineer the proposed development and waterline relocation will have no adverse impacts and is geotechnically feasible if the recommendations of the geotechnical report are incorporated into the design and sufficient geotechnical monitoring is incorporated into the construction phases of the project. As a condition of approval, the applicant will be required to follow the recommendations of the geotechnical report for all development activities on the site and to submit a copy of the report with each building permit application on Lots 6-8. Compliance will be assured at the time of building permit application. As conditioned, this standard is met. Drainage Standard for Major Developments, Partitions, Subdivisions, and Certain Structures [LOC 50.06.006.3.b] This standard requires new development to detain and treat surface water before discharging to the public storm drain system, creeks or other receiving bodies of water. The determination of whether or not the application complies with the requirements of this standard is under the review authority of the City Manager or City Engineer. The City Engineer has made the following findings and recommendations: Existing Drainage Characteristics The existing site contains a single-family home with an asphalt driveway that loops through the site around the existing home (Exhibit E3). The existing landscape consists of established lawn and landscaping with scattered trees. There is an existing stream channel located on the eastern portion of the site. Onsite slopes range from approximately 0 to 70 percent, with the majority of the steeper slopes being at the northern portion of the site (Exhibit E3). The majority of the proposed development area has slopes of approximately 10 percent. The existing curbed driveway that loops through the property collects runoff from the westerly approximate two-thirds of the site and then directs the runoff toward Cedar Street. There is a public collection system in Cedar Street and a 10 -inch storm system that conveys the drainage between 1001 and 1017 Cedar Street, under the back yards of 1102 and 1112 Erickson Street, and then ties into the drainage system in Laurel Street. The City has recently video scoped this system and identified some restrictions due to root intrusion, which has been be noted as part of City maintenance. The easterly approximate one-third of the site drains toward the stream channel that crosses the northeast corner of the site. This runoff is collected in a ditch inlet and conveyed north in a 12 -inch storm pipe between 1123 and 1133 Erickson Street, and then ties into the drainage system in Laurel Street. The northern portion of the site (north of the existing driveway curb) drains directly north in between 1122 and 1132 Erickson Street into a storm pipe that collects drainage from the retaining wall footing that was constructed as part of landslide repair in 1987. LU 14-0046 Page 16 of 33 Uphill Drainage Characteristics The area uphill (south) of the site is Freepons Park which has a large landscaped lawn and a vegetated forest. Beyond the park are detached single-family homes with established landscaping. There is a delineated stream channel that enters the site at the southeast corner and flows approximately 70 feet north to a ditch inlet (Exhibit E3). The upstream basin area draining to the stream is approximately 25 acres and drainage to this stream channel will remain unchanged as a result of this development. Infiltration The project geotechnical engineer does not recommend the use of open detention or stormwater infiltration facilities due to the potential for adverse impacts to slope stability (Exhibit F4). The Engineering staff concurs with this recommendation because of the sloping topography and measured infiltration rates of 0.1 to 2.6 in/hr., and also noting there has been a past slide repair made along the northern portion of the site. The geotechnical engineer recommends prior fill along the northern slope be removed. Proposed Drainage The applicant has provided a preliminary drainage report (Exhibit F7) and preliminary site and utility plan (Exhibit E12) prepared by a registered engineer, demonstrating that the proposed stormwater management design features comply with this standard. As indicated in the drainage report, roof drains from each of the new homes will be routed to vegetated planter boxes, located on each lot. Each vegetated planter box shall be installed with the individual building permits for each home. The individual planter boxes will be designed and sized to treat the runoff for water quality. Because the final planter box footprint size is subject to the custom design of each home, the final design layout will be reviewed at the time of building permit issuance. Each future building permit application for the individual lots will be required to have final design calculations for the planters to ensure they are adequately sized for the new home on each lot. After water quality has been provided on each lot, the stormwater will then be conveyed to the underground detention facility located at the west end of the private access lane. The detention facility volume will be sized for the maximum difference between the runoff volume for the 50 -year storm event from the post -developed site conditions and the runoff volume for the 10 -year storm event from the pre -developed site conditions. The preliminary sizing of the detention facility in the drainage report indicates that the volume is based on an assumed 3,000 square feet of impervious area per lot for building roof and driveways, for a total of 24,000 square feet for these areas. The Engineering staff notes that the final sizing of the detention volume will need to demonstrate that adequate volume will be provided based on the actual total square footage of imprevious areas (homes/driveways) being constructed on the lots. The applicant will be required to submit a final drainage report before the plat is recorded to ensure that the total required detention volume will be provided. In addition, the applicant will be required to provide verification that the detention volume is provided in accordance with the final drainage report at the time of building permit review on each lot. Stormwater from the access lane (excluding the paved turnaround) and driveways (excluding Lot 5 driveway) will drain into a bioswale along the north side of the access lane. Driveways for Lots 6-8 will be graded to drain to the bioswale. Each lot will be provided with an individual private storm drain lateral to collect the runoff from the vegetated planter boxes that will be on these lots. A new private storm drain line located in the access lane will collect all stormwater runoff from each of the lots. Stormwater LU 14-0046 Page 17 of 33 from the vegetated planter boxes, access lane bioswale, and the trapped catch basin at the end of the turnaround will be collected in the private storm drain line and be conveyed to the new underground detention facility located at the west end of the access lane. From the underground detention facility, the stormwater will then be conveyed through a flow control manhole to the existing public drainage system located in the Cedar Street right-of-way. The west portion of the access lane cannot drain to the bioswale due to topographic constraints. Stormwater from this portion of the access lane will be conveyed to a vegetated planter box located at the northwest corner of Lot 8 where it will be treated and then conveyed to the stormwater main located within the access lane. A portion of the paved turnaround at the east end of the private access lane will not drain to the bioswale due to topographic and grading constraints. This runoff will be collected in a trapped catch basin and will be routed to the detention facility. The stormwater from the Lot 5 driveway also cannot be conveyed to the bioswale. Surface runoff from this driveway will be conveyed to the private vegetated planter box on that lot and then routed to the detention facility. Foundation Drains Foundation drains from the individual homes will also be collected in the common conveyance system for the development. Due to topography, a private storm drainage easement will be needed across Lots 7 and 8. Downstream Drainage System Analysis A downstream analysis was included with the storm drainage report. The downstream conveyance system was analyzed for approximately 800 feet to an open channel discharge point at the intersection of Laurel Street and Dyer Street. At the open channel discharge point (end of analysis), this site's area is equivalent to less than four percent of the total upstream basin area. The results of the analysis show that the downstream conveyance pipes have adequate capacity to convey runoff from the 25 -year storm event, including runoff contributed from the developed project site. Based on the results of the downstream conveyance analysis, no downstream improvements are needed for this development. As noted earlier though, the City has recently video scoped this system and identified some restrictions due to root intrusion. Maintenance All of the common on-site private drainage facilities will be required to be maintained by the homeowners association (HOA). The common drainage facilities include the common conveyance pipes and detention system within the access lane, bioswale, catch basin at the end of the turn around and the planter box at the northwest corner of Lot 8. The applicant will be required to submit an Operations and Maintenance Plan for the private on-site storm facilities and record a Declaration of Covenant for Operation and Maintenance of Surface Water Management Facilities. The Engineering staff finds that as conditioned, the proposed stormwater design will comply with this standard. Solar Access [LOC 50.06.007] This standard requires that 80 percent of the parcels resulting from a subdivision approval must comply with the solar design standard [LOC 50.06.007.1.d]. Seven of the proposed LU 14-0046 Page 18 of 33 parcels must, therefore, comply with one of three alternatives: (a) Basic Requirement; (b) Protected Solar Building Line Option; or (c) Performance Option; or the applicant may show that they qualify for an exemption or adjustment to the design standard per LOC 50.04.004.1 or 2. As illustrated on Exhibit E7, all of the lots comply with the Basic Requirement because they all have a north -south lot dimension greater than 90 feet and the front lot line is oriented within 30° of a true east -west axis. All eight lots will be subject to the provisions of LOC 50.06.007.2, which protects development of solar lots from future shade. The applicant/owner will be required to file a notice of development restriction with the Clackamas County Recorder binding the applicant and subsequent purchasers of property to comply with the future shade protection standards of the section. This covenant shall not be amended without prior written City approval. As conditioned, this standard is met. Utilities [LOC 50.06.008] The Engineering staff has reviewed the subject application and finds that utilities are available or can be made available as follows: Sanitary Sewer: There is an existing 8 -inch public sanitary sewer main located in Cedar Street that currently terminates with a manhole in front of 1004 Cedar Street. An 8 -inch public sewer extension within a minimum 15 -foot wide public sanitary sewer easement will be required into the site to serve the 8 -lot subdivision. The preliminary site and utility plan (Exhibit E12) illustrates that a new public sanitary sewer main will be constructed in the access lane within a public sanitary sewer easement. This main shall be eight inches in diameter. The Engineering staff notes that to ensure the manhole located in front of Lot 1 will be located within the paved area, a condition of approval will be imposed requiring the driveway for Lot 1 to be located on the west side of the lot. This driveway approach from the access lane shall be constructed along with the access lane improvements. Water and Hydrants: The City owns and maintains a 10 -inch water main in Cedar Street and along the north boundary of the site, where it reduces down to an 8 -inch main across the northeast portion of the site and connects to the main in Hallinan Circle. There is also an 8 -inch public water main located in Bickner Street which completes a loop system in Spruce Street and Cedar Street. The closest fire hydrant is located in front of 1002 Cedar Street along the south side of the street. The Engineering staff notes that the public waterline will not be allowed to be located across the back yards of the lots and will need to be relocated. The new line will be allowed to be located in the access lane within a public easement. The preliminary site and public utility plan (Exhibit E12) shows that the existing waterline will be relocated and routed under the access lane within a public water easement and tie back into the existing water main at the northeast corner of Lot 6. The water main size shall match the existing diameter. The Engineering staff also notes that the subdivision design will be dependent on the Cedar Street right-of-way that juts into the site off the east end of the cul-de-sac being LU 14-0046 Page 19 of 33 vacated (Exhibits E3 and E7). Staff will support this section of right-of-way to be vacated subject to a condition that the existing public waterline be relocated under the access lane. This will relocate the water line outside of the past landslide area. As noted in Exhibit F6, the geotechnical engineer states "The proposed waterline relocation will have no adverse impacts and is both geotechnically feasible and recommended." The Fire Marshal finds that the existing hydrant location and fire flow are adequate for the proposed development (Exhibit F3). Streets: Cedar Street is an approximately 32 -foot wide two-lane local street in a 60 -foot wide right-of-way. The street is under the jurisdiction of the City of Lake Oswego and the pavement is in very poor condition. The pavement width narrows toward Cornell Street west of the site. The existing right-of-way width varies around the cul-de-sac and then extends east beyond the end of the cul-de-sac with a 30 -foot width, for approximately 160 feet. See LOC 42, below, for additional analysis of the required street improvements. Sidewalks: There are no existing sidewalks in the immediate vicinity of the site. Other utilities: It is the applicant's responsibility to ascertain the availability of electric, gas, telecommunications and cable TV. All new utilities shall be installed underground. 3. Any additional statutory, regulatory or Lake Oswego Code provisions which may be applicable to the specific minor development application; Streets and Sidewalks FLOC Chapter 421 This Chapter authorizes the City Engineer to make specific street and sidewalk improvement recommendations after taking a variety of policy and site specific factors into consideration.' The City Engineer's comments are included for review of the overall understanding of the project. The City Engineer's conditions of approval are included, as they must be included in the decision, to find that the application will comply with this article. The Engineering staff has reviewed the development proposal and field conditions in the context of the City's codes, improvement policies and Transportation System Plan (TSP), and offers the following findings and conditions of approval. The proposed development can be expected to contribute 10 vehicle trips to the City's street system per lot per average weekday.' Additional pedestrian and bicycle trips can be expected as well. The cumulative effect of new trips (all modes) imposes an additional burden and concomitant concerns for preserving street capacity and public safety, particularly for bicycles and pedestrians. Per LOC 50.07.003.5a.iii, conditions may be imposed to alleviate a need for public services or facilities created 'To meet the review criteria for a minor development, the applicant must comply with "any additional ... Lake Oswego Code provisions which may be applicable to the specific minor development application, such as ... the Streets and Sidewalks Ordinance." LOC 50.07.003.14.d. The determination of whether or not the application meets the requirements of LOC Chapter 42, Streets and Sidewalks, is under the review authority of the City Manager or City Engineer; the requirements of this Chapter are not under the review authority of a hearing body, other than to find whether or not the City Engineer or City Manager has found that the application complies with LOC Chapter 42, or whether conditions of approval are required for compliance with this Chapter. 'Trip Generation (8t" edition), Institute of Transportation Engineers LU 14-0046 Page 20 of 33 or contributed to by the proposed development. "Public services or facilities" include streets, sidewalks and pathways. The City has a governmental interest in assuring that new development does not contribute to a degradation of adequate, safe and efficient public transportation facilities. New development should mitigate the negative impacts (increased noise, and the degradation of aesthetics, safety, system capacity, and bicycle and pedestrian mobility) resulting from new development. The City has adopted a broad array of policies, plans, regulations, and fees that have been designed to offset the adverse impacts of development on the natural and built environment. In this regard, the following regulations and standards reflect the governmental interest in preserving the functionality and safety of the public infrastructure, and are particularly relevant to this development proposal: LOC Chapter 42 requires frontage improvements to be constructed when property is developed. LOC Chapter 42 directs the City Engineer to determine the appropriate width of public rights-of-way, and the width and character of the improvements contained therein. The implementation of the City's plans, policies, and regulations will offset to some degree the negative impacts of development on the public infrastructure. LOC 50.07.003.5 allows the reviewing authority to impose conditions of approval on a development permit when the condition is reasonably related to alleviation of a need for public services or facilities created or contributed to by the proposed development. In addition, the US Supreme Court has rule (Dolan v. City of Tigard) that in order to require mitigation, the local government must apply a test of "rough proportionality" between the impacts of the proposed development and the need for the mitigation to offset impacts from the development. The Engineering staff has conducted further review of the street improvement requirements for this development. Cedar Street is a local street, and the existing pavement along Cedar Street from Cornell Street to the site is in poor condition. With the development creating seven net new home sites that will be using this section of road, the vehicle trip generation will increase by approximately 70 vehicle trips per day, roughly a 50% increase. To alleviate to a degree a need for public services or facilities created or contributed to by the proposed development, a condition of approval will be imposed on this development requiring Cedar Street pavement section to be brought up to structural pavement standards for a local street, from the west property line of 1037 Cedar Street (Tax Lot 6900), up to and including the cul-de- sac fronting the site, which is roughly 50% of the length of street between Cornell Street and the site. As a condition of approval of the proposed development, the City will require the following street improvements to alleviate impacts created or increased by the proposed development: Reconstruct Cedar Street pavement section to local street standards, from the west property line of 1037 Cedar Street (Tax Lot 6900), up to and including the cul-de-sac fronting the site. LU 14-0046 Page 21 of 33 The City finds that the public street improvements are directly related to alleviating the increased traffic, bike, and pedestrian trips that will be created by this development. Staff notes that that final design elements related to the street design shall be to the satisfaction of the City Engineer. Staff finds that requiring the public street improvements is roughly proportional to the adverse impacts upon the public services and facilities created by the development because: • The development will generate 10 additional vehicle trips per additional lot per day using Cedar Street and the adjacent local street system. • The additional site generated traffic creates an increased point of conflict between pedestrian and bicycles using the adjacent street system. By providing the public street improvements along Cedar Street and through the development, the public safety will be maintained. • Similar public street improvements have been required for similar developments within the City, with the result being that such development conditions for street improvements have mitigated the increased traffic (vehicle, pedestrian, and bicycle) by preserving the functionality and public safety features of the public street system. In light of the above facts and Code requirements, staff finds that the development of this site will place sufficient additional demand on the local streets to justify the street improvements at this time, and that the required street improvement are roughly proportional to the degree of impact imposed by the new development, as described above, and consistent with the improvements of similar developments of land within the City, as required by LOC 50.07.003.5 and the U.S. Supreme Court in the case of Dolan v. the City of Tigard. Vision Clearance FLOC 42.03.1301 This standard requires that no vegetation, fence, or signage be located higher than 30 inches within a "vision clearance triangle." The vision clearance triangle for driveways is formed by 10 -foot legs extending from the intersection of the edge of driveway and the street travel lanes. The applicant's sight distance and vision clearance triangle plan (Exhibit E11) indicates that the access lane approach with the Cedar Street cul- de-sac will meet this standard. In addition, the vision clearance triangles for the driveway access points onto the access lane shall be included on the plans for the building permit applications. Compliance with this standard will be assured at the time of building permit application on each lot. City of Lake Oswego Tree Code KOC Chapter 551 The Tree Code is intended to preserve trees. Only those trees that must be removed in order to site proposed improvements will be granted tree cutting permits under LOC 55.02.080. TrPP RPmnval As illustrated on Exhibit E9, there are 112 trees on the site that are five inches in diameter or greater. The applicant is requesting to remove a total of 13 trees as part of the LU 14-0046 Page 22 of 33 application (Exhibit E9). The trees consist mainly of fruit tree species, but also includes a sweetgum, magnolia, red maple, willow, and a northern catalpa. The trees range in size from six inches to 24 inches in diameter. The applicant has also illustrated a total of eight invasive trees and one hazard tree that will be applied for under separate tree removal applications (Exhibits E9 and F1). Trees proposed for removal in conjunction with a minor development can be granted tree removal permits if the following criteria are met: 1. The removal is for development purposes allowed pursuant to the City Code, The removal of the 13 trees is necessary for development because they are located within the areas of proposed site improvements as illustrated on Exhibits E10 and E12. 2. The removal will not have a significant negative impact on erosion, soil stability, flow of surface waters, protection of adjacent trees, or existing windbreaks; The removal of the 13 trees will not have a significant negative impact on erosion, soil stability, or flow of surface waters because they are located on relatively flat areas of the site and are not being removed from the stream corridor on the east side of the site (Exhibit E9). The removal will not have a significant negative impact on protection of adjacent trees or existing windbreaks because the 13 trees are scattered around the site and spaced far apart from other trees; therefore, they do not provide a significant wind break or protection to adjacent trees. 3. The removal will not have a significant negative impact on the character, aesthetics, or property values of the neighborhood, except when alternatives to tree removal have been considered and no reasonable alternative exists to allow the property to be used as permitted in the zone, and The 13 trees to be removed are primarily located in the interior of the site and trees around the perimeter of the site are not proposed for removal (Exhibits E4 and E9). Eight of the trees are fruit trees that are of shorter stature and the two largest trees (24" sweetgum and 18" willow) are located in the interior of the site where they are not highly visible. Staff finds that the tree removal will not have a significant negative impact on the character, aesthetics or property values of the neighborhood. 4. The removal is not for the sole purpose of providing or enhancing views. The trees are not being removed for view enhancement because their removal will not improve any views. For the reasons outlined above, staff concludes that the removal request for the 13 trees complies with the applicable criteria and may be approved. The applicant shall apply for a verification tree removal permit for the 13 trees prior to approval of any construction plans. The applicant should apply for permits to remove the eight invasive trees and one hazard tree identified on Exhibit E9 as separate tree removal applications. LU 14-0046 Page 23 of 33 Mitigation Any tree approved for removal under the Type II tree analysis shall be mitigated at a minimum 1:1 ratio. Required street trees do not count towards the minimum tree mitigation requirements. Mitigation trees should have a minimum 2 -inch caliper diameter for deciduous trees and a minimum 6-8 foot height (excluding leader) for evergreen trees. The applicant proposes to plant 13 two-inch caliper big leaf maples as mitigation (Exhibit E14) in addition to the required street trees along the access lane. This standard is met. Tree/Resource Protection Tree protection fencing is required when a tree protection zone or drip line of a tree that is five inches in diameter or greater is within the construction zone, whether on or off-site. As authorized by LOC 55.08.020, a tree protection application and plan should be submitted for staff review and approval prior to conducting any development activities on the site, including, but not limited to clearing, grading, landscaping, or excavation. A tree/resource protection plan shall be submitted for staff review and inspection prior to commencing any construction activities. Tree protection fencing shall be placed at the tree protection zone, which is the zone required to protect the critical root area necessary for the continued health of the tree and at the edge of the delineated RP district, except where necessary to remove the nonconforming driveway and to construct a soft surface path within the RP District. The applicant shall propose the tree/resource protection zone for review and approval by City staff, on site. As required by LOC 55.08.030(7), no construction, excavation, root pruning or other activity shall occur within the tree/resource protection zone unless directed by an arborist present on site as approved by the City and supported by an arborist report. The applicant will be required to assure that a consulting arborist will be available for services as described above if any construction activities are proposed within the tree protection zone. The tree/resource protection plan shall clearly illustrate all areas impacted by construction activities on the site (including driveway and utility construction and landscaping), the location of temporary fencing around the tree protection zone of all trees five inches in diameter or greater where the construction zone is within the drip line of a tree, or other tree protection measures as recommended by a certified arborist. In addition, a note should be placed on the fencing and on the construction documents that informs the site contractors about the necessity of preventing damage to the trees, including bark and root zone, and that no materials should be stored nor compaction occur within the root zones of the adjacent trees [LOC 55.08.030]. As conditioned, this standard can be met. 4. Any applicable condition of approval imposed pursuant to an approved ODPS or prior development permit affecting the subject property. There are no conditions of approval of prior City development permits affecting the subject property. LU 14-0046 Page 24 of 33 VII. CONCLUSION Based upon the materials submitted by the applicant and findings presented in this report, staff concludes that LU 14-0046 complies with all applicable criteria and standards or can be made to comply through the imposition of conditions. VIII. RECOMMENDATION Staff recommends approval of LU 14-0046, subject to the following conditions: A. Prior to Approval of the Final Subdivision Plat, the Applicant/Owner Shall: 1. Apply for and receive approval from the City Council to vacate the portion of the Cedar Street right-of-way that juts into the property at the end of the cul-de-sac. 2. Submit a final plat to staff for review and signature of approval within one year of the date of this decision. The deadline for submitting the final plat to City staff is December 1, 2015. The final plat must be dimensioned as depicted in Exhibit E7 and reference this land use application — City of Lake Oswego Planning and Building Services Department Case File LU 14-0046. Upon written application, prior to expiration of the one-year period, the City Manager shall, in writing, grant a one-year extension. Additional extensions may be requested in writing and must be submitted to the City Manager for review of the project for conformance with current law, development standards and compatibility with development that may have occurred in the surrounding area. The extension may be granted or denied and, if granted, may be conditioned to require modification to bring the project into compliance with then current law and compatibility with surrounding development. 3. All plats and public easements submitted to the City of Lake Oswego shall have accompanying vector based electronic drawings or maps consistent with the prevailing technologies in the Civil Engineering and/or Surveying fields (e.g. current or near current versions of AutoCAD). The electronic drawings shall conform to the mapping requirements for plats adopted in O.R.S. Chapter 92. 4. The final plat shall illustrate the following to the satisfaction of staff: A minimum 15 -foot wide public sanitary sewer easement over the private access lane for the public sewer extension into the site. b. A minimum 15 -foot wide public water easement over the access lane and along the east edge of Lot 6 for the relocation of the public water line. c. Public utility easements to the satisfaction of the franchise utility companies. d. Private storm easements for the development's common storm facilities throughout the development, which will provide conveyance from the individual storm facilities on each lot and from the bioswale, access lane planter box on Lot 8 and catch basin along the access lane. e. A private access easement over the access lane serving all the lots. f. A public drainage easement over the existing public storm lines on the site. g. A public water easement over the existing public water line on the site. LU 14-0046 Page 25 of 33 h. A private drainage easement across Lots 7 and 8 for the foundation drains that will be constructed for Lots 6 and 7. i. A private pedestrian access easement for the pedestrian path in the open space tract from the end of the access lane to the Freepons Park to the south. 5. Record the private access easement over Tax Lot 5101 abutting the site to the west as illustrated on Exhibit E7 and provide a copy of the recorded document to the City prior to recording the subdivision plat. 6. Submit a "Notice of Development Restrictions" to be recorded with the final plat after review and approval by staff. A reduced copy of the preliminary subdivision plat showing setbacks (Exhibit E7), and a plan showing the delineated RP District shall also be incorporated in the notice of development restriction as Exhibits "A" and "B". The exhibits shall be no larger than 8 %" x 11" and shall not contain lettering smaller than 10 point font. The "Notice of Development Restrictions" shall include the following: Lots 1-8 are flag lots. Development of structures on these lots shall comply with the provisions of LOC 50.07.007.2 regarding building and site design standards, including height limitations, garage placement, and landscape buffer requirements. The following site development restrictions apply: The maximum height of all structures on Lots 1-8 shall be 22 feet measured from the ground to the ridgeline of the roof as defined by LOC 50.10.003.2 "Height of Building." ii. The front lot lines of Lots 1-8 shall be oriented towards the access lane as depicted on Exhibit A. The required front, side and rear yard setbacks shall be as follows: Lot Front Yard Side Yard Setbacks Rear Yard # Setback measured Setbacks from access lane 1 10 feet 25 feet 2 10 feet 25 feet 3 10 feet 25 feet 10'— dwelling 4 10 feet 25 feet 20' —garage opening 5 10 feet (west) 16 feet facing access lane 19 feet (east) 6 10 feet 25 feet 7 10 feet 25 feet 8 10 feet (east) 10 feet 26 feet (west) iii. There shall be a 5 -foot landscape buffer and a 6 -foot fence along the north property lines of Lots 6-8, except that the height of the fence shall be stepped down to four feet on Lot 8 within 10 feet of the Cedar Street right-of-way. In LU 14-0046 Page 26 of 33 addition, there shall be a 6 -foot fence along the portion of the west property line of Lot 1 that abuts Tax Lot 4900. All or a portion of these requirements may be waived if the applicant can meet the provisions of LOC 50.07.007.2.f.iii. b. The property contains a delineated Resource Protection (RP) District as illustrated on Exhibit B, and as determined and documented in City of Lake Oswego Planning and Building Services Case File LU 14-0046. Future development in the RP District is subject to the City of Lake Oswego code requirements and development standards set forth in LOC 50.05.010. Contact the City of Lake Oswego Planning and Building Services Department prior to commencing any activity inside the RP District. c. Lots 1-8 are solar lots, subject to the requirements of LOC 50.06.007.2 (Solar Balance Point). Development of structures or planting of non-exempt vegetation on Lots 1-8 shall comply with the Solar Balance Point provisions of the Solar Access Ordinance (LOC 50.06.007.2). These requirements shall be binding upon the applicant and subsequent purchasers of Lots 1-8. The Building Official may allow an alternative to the minimum requirements of the One -and Two -Family Dwelling Specialty Code as authorized by ORS 455.610, which may include, but is not limited to, installation of an automatic fire sprinkler system, because the City of Lake Oswego has determined the fire apparatus means of approach to Lot 2-7 does not meet the local City standards adopted in accordance with the applicable Fire Code and state building code requirements. The owners or owners' representative shall install an approved alternate method for fire suppression, such as an NFPA 13-D residential fire sprinkler system on Lots 2-7, to the satisfaction of the Fire Marshal and Building Official. 7. Submit CC&Rs of the homeowners association for review and approval of staff that includes or addresses the following: The private Open Space Tract shall remain in its natural condition to provide a scenic, aesthetic appearance; protect natural processes; provide passive recreational uses, and maintain the native vegetation of the open space. The City may approve activities that enhance the natural qualities of the open space and meet the above purpose of the open space. Trees may be removed only after they have been shown to be dead or hazardous to life or property by a certified arborist, and after a tree removal permit has been obtained from the City. A mitigation plan shall be required as part of any tree removal permit application. Improvements in this area, which are in keeping with the above purpose, including public utilities and pedestrian pathways may be approved by the City of Lake Oswego. No buildings or structures shall be allowed in the open space tract. b. Attach a maintenance agreement outlining specific responsibilities for the homeowner's association to maintain the access lane, to be recorded as an exhibit with the CC&Rs. c. The ownership, use and specific maintenance responsibilities for the following features: i. Private pedestrian pathway through the open space tract (with maintenance responsibility by the homeowners association.) LU 14-0046 Page 27 of 33 ii. Access and maintenance of the landscaping and street trees along the access lane as shown on Exhibit E14. Upon transfer of the homeowners association from the developer to the homeowners within the development, the City shall be notified of the name and address of a contact person for the homeowners association. e. Upon election of new officers for the homeowners association, the City shall be notified of the new contact person. The City's right to enforce the provisions of the CC&Rs required, above, including the right to recover all expenses of enforcement, the right to lien the lots to secure enforcement expenses, "non -waiver" of enforcement, non -amendment or rescission of the provisions of the CC&Rs required, above, and indemnification to the City for claims arising from the failure to properly design, locate, construct, or maintain the open space tracts or stormwater facilities. (Suggested text for this requirement may be obtained from the City Attorney's office.) 8. Submit engineered construction plans and an itemized cost estimate for review and approval by the City Engineer. Drawings shall conform to the City's current design standards and the drafting specifications. [Note: receiving construction plan approval is not a pre -requisite for recording the final plat.] The plans shall include design for the following: a. Design for reconstruction of the Cedar Street pavement section from the west property line of 1037 Cedar Street (Tax Lot 6900), up to and including the cul-de-sac fronting the site, to local street standards. b. A public storm main extension from the existing storm main located in the Cedar Street cul-de-sac to the edge of the right-of-way at the east side of the cul-de-sac. c. An 8 -inch public sewer extension from the existing sewer located in Cedar Street through the site in the access lane, and terminating with a manhole in front of Lot 5. The driveway on Lot 1 shall be located on the west side of the lot. This driveway approach from the access lane shall be constructed along with the access lane improvements. d. Relocation of the public water line from the Cedar Street cul-de-sac to the northeast corner of Lot 6. The new water line shall match the diameter of the existing water line and be routed under the access lane within a public water easement. e. Access lane approach onto the Cedar Street cul-de-sac to City and AASHTO standards. The maximum width of the driveway approach, where the approach meets the right- of-way line shall be 24 feet. f. Individual private water services, sanitary service laterals and storm laterals. 9. Submit engineered construction drawings for the private on-site improvements for review and approval of staff. 10. Submit for review and approval of staff a final storm drainage report prepared by a registered engineer, for all required storm improvements. 11. Submit for the City Engineer's review and approval a Declaration of Covenant for Operation and Maintenance of Surface Water Management Facilities for the common stormwater facilities to be maintained by the homeowners association (HOA) and LU 14-0046 Page 28 of 33 record with the final plat. The common drainage facilities include the common conveyance pipes and detention facility within the access lane, bioswale along the north side of the access lane, catch basin and the planter box at the northwest side of Lot 8. 12. Complete all public improvements required by Condition A(8), above, or submit a financial guarantee to ensure their completion per LOC 50.07.003.9. The financial guarantee shall be based on an itemized engineer's estimate of the public improvements that is in turn based on plans that are far enough advanced to support the estimate, to the satisfaction of the City Engineer. 13. Submit a final landscaping plan for review and approval of staff. The plan shall be in accordance with Exhibit E14, with the following modifications: a. Illustrate the location, size and species of native plant materials to mitigate for the disturbed area within the RP District on either side of the soft surface pathway through the open space tract. The RP mitigation shall be prepared by a qualified resource professional. b. Illustrate a 6 -foot tall (except that the maximum height shall be four feet within 10 feet of the Cedar Street right-of-way) sight -obscuring fence along the west property line abutting the access lane between Cedar Street and the northern boundary of Lot 1. As an alternative, the applicant may illustrate a 5 -foot landscape buffer on the abutting lot to the west that is owned by the applicant (Tax Lot 5101). If this option is selected, the landscaping shall be of a size to provide an effective screen within two years of planting. Trees shall be a minimum of 2 -inch caliper and shrubs shall be a minimum of five gallon in size at the time of planting. The applicant shall also be required to record a landscape easement on Tax Lot 5101 and submit a copy of the recorded easement to the City. 14. Submit an RP Mitigation, Monitoring, and Maintenance Plan for the RP mitigation required by Conditions A(13)(a), above, stating that all native plants will be replaced as needed throughout the monitoring period to ensure an 80% survival rate, and invasive plants will be removed to ensure less than 5% cover of invasive species. The plan shall state that any replacement species must be approved by the City, and that the applicant or other legally responsible agent shall provide an annual report to the City Manager by October 31 of each year for a three-year period. B. Within 30 Days of the Recordation of the Final Plat, the Applicant/Owner Shall: 1. Submit a title report, or lot book report from a title company showing that all public and private easements as required in Condition A(4), the "Notice of Development Restrictions" as required in Condition A(6), the CC&R's as required in Condition A(7), and the Declaration of Covenant for Operation and Maintenance of Surface Water Management Facilities required in Condition A(11), above, are valid and subsisting, and either free of any prior liens or encumbrances, or holder of prior liens and encumbrances shall submit a Consent Affidavit. LU 14-0046 Page 29 of 33 C. Prior to Constructing the Public Improvements or Issuance of a Site Grading Permit, the Applicant/Owner Shall: Obtain any necessary building permits and move or demolish all existing structures on the site. The applicant shall note that an asbestos report from a licensed agency may be required for a demolition permit to the satisfaction of the Building Official. Permits to demolish or move structures on the site shall be accompanied by proper applications for tree protection and erosion control permits, if needed. 2. Apply for and obtain a verification tree removal permit for the 13 trees approved for removal by this action. The Verification application shall include an 8%" x 11" copy of the tree removal plan (Exhibit E9) and mitigation plan that shows replacement trees on a 1:1 basis. Replacement trees shall not be dwarf or ornamental varieties and shall be at least two inches in caliper if deciduous or at least six to eight feet tall, excluding the leader, if evergreens. The trees shall be of a species that will obtain a minimum height of 30 feet at maturity. 3. Submit final construction plans that specify the location of a minimum 6 -foot high cyclone temporary protection fencing along the RP District boundary (except in the areas where the existing asphalt driveway will be removed and the soft surface pathway will be installed) and compliance with the Sensitive Lands Construction Standards in LOC 50.05.010.4.d. 4. Install the tree protection fencing as required by Code Requirement No. 1, below. D. Prior to the Issuance of a Building Permit on any of the Lots, the Applicant/Owner Shall: 1. Demonstrate compliance with Conditions A -C, above. 2. Complete all public and site improvements as required by Condition A(8), above, submit certified "as -built" drawings, and receive a certificate of completion and acceptance by the City. 3. Complete construction of the private sanitary services, common private storm facilities, storm lines and laterals, private water services and private franchise utilities serving all of the lots as required by Conditions A(8) and A(9), above. 4. Submit a stormwater plan for the water quality planter boxes on each lot to the satisfaction of the City Engineer. Overflow pipes shall be directed to an approved point of disposal. The driveway for Lot 5 shall be routed to the planter box on that lot. In addition, the applicant shall provide verification that the detention volume is provided in accordance with the final drainage report required by Condition A(10), above, with the building permit on each lot 5. Submit a copy of the geotechnical report (Exhibits F4 -F5) with each building permit application on Lots 6-8. 6. Show the vision clearance triangles on the site plans for building permit applications on each lot. LU 14-0046 Page 30 of 33 7. Per LOC Chapter 52, apply for and obtain an approved erosion prevention and sediment control permit issued through the City of Lake Oswego, and install and maintain all BMPs as indicated in the permit. These measures must remain in place as indicated throughout the development period. 8. Install construction protection measures for the access lane bioswale in order to protect the facility during home construction. The protection measures for protecting the access lane bio swales shall be left in place until after the final home construction has been completed. 9. Each building permit application shall be accompanied by a topographic survey plan showing the existing site grade at one -foot contour intervals and the approved final grading plan to ensure compliance with the maximum building height standards. Building height shall be measured from the existing (pre - grading) grade where fill has occurred and the finished grade where the grade has been cut. 10. Install all landscaping and mitigation trees and construct the soft surface pathway in the open space tract. 11. Install the six-foot tall sight -obscuring fence or landscape buffer along the west property line abutting the access lane between Cedar Street and the northern boundary of Lot 1 as required by Condition A(13)(b), above. 12. Apply for the appropriate tree removal permits on each lot and include a mitigation plan. For mitigation, deciduous trees shall have a minimum caliper of two inches and conifer trees shall be a minimum of six to eight feet high (excluding the leader). All mitigation trees shall be of a species that will obtain a minimum height of 30 feet at maturity. 13. Install an address display sign that is visible from Cedar Street. This sign may be of a temporary nature while homes are being built. A permanent sign shall be required upon completion of 50% of the new dwellings served by the access lane. The permanent address display sign shall have numerals at least six inches in height and shall be clearly visible from Cedar Street. 14. Install permanent "No Parking— Fire Lane" signs on both sides of the portion of the access lane that is less than 26 feet in width, on the south side of the portion of the access lane that is 26 feet in width, and in the turnaround at the end of the access lane to the satisfaction of the Fire Marshal. The signs shall have a minimum dimension of 12 inches wide by 18 inches high and have red letters on a white reflective background. Prior to any Final Building Inspection or Occupancy of any Dwelling on any Lot, the Applicant/Owner Shall: 1. Provide certification from the engineer of record that the stormwater planter box for each lot was constructed according to the design and is functioning properly. 2. Install required mitigation trees on each lot as required by Condition D(12), above. LU 14-0046 Page 31 of 33 3. Install the landscaping and street trees along the access lane on each individual lot, and install fencing and landscape buffers in the rear yard on Lots 6-8 and fencing along the portion of the west side yard of Lot 1 abutting Tax Lot 4900, as required by Condition A(13), above. On Lot 8, the fence shall be stepped down to four feet in height within 10 feet of the Cedar Street right-of-way. Code Requirements: Note: Tree Protection: Submit a tree protection plan and application as required by LOC 55.08.020 and 55.08.030 for review and approval by staff, including off-site trees that are within the construction zone. The plan shall include: a. The location of temporary tree protection fencing, consisting of a minimum 6 -foot high cyclone fence secured by steel posts around the tree protection zone, or as recommended by the project arborist and approved by the City. b. A note stating that no fill or compaction shall occur within the critical root zones of any of the trees, or that if fill or compaction is unavoidable, measures will be taken as recommended by a certified arborist to reduce or mitigate the impact of the fill or compaction. The note shall also inform contractors that the project arborist shall be on site and oversee all construction activities within the tree protection zone. c. A note that clearly informs all site contractors about the necessity of preventing damage to the trees, including bark and root zone. The applicant and contractor(s) shall be subject to fines, penalties and mitigation for trees that are damaged or destroyed during construction. d. A sign shall be attached to the tree protection fencing which states that inside the fencing is a tree protection zone, not to be disturbed unless prior written approval has been obtained from the City Manager and project arborist. The applicant is advised to take part in a Post Land Use Approval meeting. City staff would like to offer you an opportunity to meet and discuss this decision and the conditions of approval necessary to finalize the project. The purpose of the meeting is to ensure you understand all the conditions and to identify other permits necessary to complete the project. If you like to take advantage of this meeting, please contact the staff coordinator at (503) 635-0290. Development plans review, permit approval, and inspections by the City of Lake Oswego Development Review Section are limited to compliance with the Lake Oswego Community Development Code, and other applicable codes and regulations. The applicant is advised to review plans for compliance with applicable state and federal laws and regulations that could relate to the development, e.g., Americans with Disabilities Act, Endangered Species Act. City staff may advise the applicant of issues regarding state and federal laws that the City staff member believes would be helpful to the applicant, but any such advice or comment is not a determination or interpretation of federal or state law or regulation. LU 14-0046 Page 32 of 33 FXHIRITC A -D. [No current exhibits; reserved for hearing use] E. GRAPHICS/PLANS E1. Tax Map E2. Cover Sheet E3. Site Survey/Existing Conditions E4. Aerial Photograph of Site E5. Building Height Survey E6. Demolition Plan E7. Preliminary Subdivision Plat E8. Fire Hose Plan E9. Tree Removal and Protection Plan E10. Grading and Erosion Control Plan E11. Sight Distance and Vision Clearance Triangles Plan E12. Site, Public Improvements, and Utility Plan E13. Street and Path Profiles E14. Landscape and Tree Mitigation Plan E15. Connectivity Plan E16. Turning Movement Plans F. WRITTEN MATERIALS F1. Applicant's Narrative F2. Summary of Neighborhood Meeting held on June 4, 2014 F3. Fire Marshal Memorandum, dated October 6, 2014 F4. Geotechnical Report, dated July 25, 2014 F5. Addendum to Geotechnical Report, dated September 24, 2014 F6. Addendum to Geotechnical Report, dated October 17, 2014 F7. Stormwater Report, dated October 2014 F8. Email from Applicant's Representative, dated November 5, 2014 G. LETTERS Neither for nor Against (G1-99) None Support (G100-199) None Opposition (G200+) None Date of Application Submittal: August 19, 2014 Date Application Determined to be Complete: October 22, 2014 State Mandated 120 -Day Rule: February 19, 2015 LU 14-0046 Page 33 of 33 g gg 0 P % k�§ ` Q LU r N w - 93 w0 wa = N Q LU O J � o w UJ o qz Q vL)jR 3: J¢ I I . 0-.fix 111, o� NVNllldH POD Lu UN '+,y� " C7d •,. g�_ � � � Ss�a a '...d � �, � ._ •• � y 1 '\CAN _ t s r-133NIS NOiONIKLU .M OURr LU f ; •` a. A.�' H 3ANG SMDOVaW •' •S@p i •' � f'' _,+ may` i a° Y f � � � =; � m; �' '" ' NO - ` "L+-- e $g B 7 �V w _+ �$•¢ �' �- ���� � ter--a,s--�V] is- Sag . 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Q� �yqE CJs � I teals aaN��re Ica � ua�n I diLoone d.rw atl n awm cw d O �• I Q� Ica � ua�n I diLoone d.rw atl n awm cw WRITTEN NARRATIVE AwM FREEPONSVILLAGE -SUBDIVISIONAPPLICATION CITY OF LAKE OSWEGO, OREGON EXHIBIT F-1 LU 14-0046 cel' 23 APPLICATIONS: 8 -lot Subdivision and RP District Delineation SU13MITTED TO: City of Lake Oswego Planning Department 380 A Avenue PO Box 369 Lake Oswego, OR 97034 OWNER: David and Debbie Craig 850 Cedar Street Lake Oswego, OR 97034 APPLICANT: Silver Oak Custom Homes 14102 Goodall Road Lake Oswego, OR 97034 APPLICANT'S AKS Engineering & Forestry, LLC CONSULTANT: 12965 SW Herman Road, Suite 100 Tualatin, OR 97062 Contact(s): Monty Hurley (monty@aks-eng.com) Chris Goodell (chrisg@aks-eng.com) Phone: (503) 563-6151 Fax: (503) 563-6152 Web: www.aks-eng.com SITE LOCATION: 850 Cedar Street ASSESSOR'S INFORMATION: Clackamas County - 21E 10DC Tax Lots 5200, 5201, 5300, 5400, and 5401 SITE SIZE: ZONING: ± 2.189 acres R-7.5 (Residential) FREEPONS VILLAGE - SUBDIVISION APPLICATION CITY OF LAKE OSWEGO, OREGON 24 SEPTEMBER 2014 (UPDATED) 1. EXECUTIVE SUMMARY Silver Oak Custom Homes is pleased to submit the Freepons Village Subdivision application to the City of Lake Oswego. The subject property is located north of Freepons Park at 850 Cedar Street in the Hallinan Neighborhood. The application features: • A low density residential project (approximately 4 units per acre) spread over 2+ acres of land including 8 future detached single-family home sites • A private access lane featuring a vegetated drainage swale and on -lane parking that meanders through the property and provides for shared access to the individual future home sites • A generously sized open space area that is dedicated to preserve and protect natural resources • Improvements to Cedar Street, including restoration of approximately 300 linear feet of the roadway The applicant envisions the project consisting of a low density, community scaled residential neighborhood of detached single-family homes blending with a protected natural resource area, Freepons Park, and the existing neighborhood. The property, City zoning, and surrounding areas and development pattern is described more fully in Section II of this written narrative and are illustrated on the preliminary plans included in the application materials. The City land use reviews that are relevant to the project are listed on the City Land Use Application Form and are described in further detail in Section 111. The applicable approval criteria are listed and addressed in detail in Section IV of this narrative. For reference purposes, a table of contents is included in the preceding pages of the application that includes a complete list of all of the materials included in the application. The findings included in this narrative, together with the accompanying documentation, demonstrate that the application is consistent with the applicable approval criteria as found in the City of Lake Oswego Municipal Code. The evidence in the record is substantial and supports the City's approval of the application. 11. SITE DESCRIPTION AND BACKGROUND The subject property is located at the existing cul-de-sac terminus of Cedar Street (classified a Local Street). A small portion of right-of-way extends beyond the physical cul-de-sac terminus of Cedar Street. This area includes a portion of the property owner's private driveway and is not improved to any City standard or utilized for any public purpose other than an underground waterline that is being removed and relocated as part of this project. This portion of the right-of-way is being vacated by the City of Lake Oswego. This increases the size of the project site by a minimal amount (+/-0.09) acres. The existing home is served by the Lake Oswego Fire Department and obtains water and sewer service from the City of Lake Oswego. Site vegetation consists mainly of lawn and landscaping around the existing home. A large grove of trees, consisting mainly of Big Leaf Maple exists in the NE corner of the property and a smaller grove of Oregon Ash can be found in the SE corner of the site. An asphalt driveway loops around the site. This driveway serves the existing home located in the center of the property. Slopes are relatively flat along the south portion of the site, but are steeper along the northern portion. There is an existing storm drainage system that collects runoff from the end of the extended Cedar Street right-of-way and conveys it to the Erickson Street cul-de-sac north of the site. There is also a storm drainage system located along the eastern portion of the site that also conveys drainage toward Erickson Street. The site is located in the Hallinan Neighborhood Association. FRFEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 2 OF 48 25 North The properties north of the site front on either Cedar Street or Erickson Street, are zoned R-7.5, and are developed with single family dwellings. South The property abutting the site to the south is Freepons Park and is zoned Parks and Natural Area (PNA). East The properties east of the site front the west side of Hallinan Circle Court, are zoned R-7.5, and are developed with single family dwellings. West The properties west of the site front the south side of Cedar Street or at the end of Spruce Street, are zoned R-7.5, and are developed with single family dwellings. The applicant is the owner of Tax Lot 5000 and the owner also owns Tax Lot 5101. III. DESCRIPTION OF APPLICATION This application for a Subdivision and RP District Delineation includes this narrative, required City application form, completed checklists, preliminary title report, preliminary project plans, preliminary stormwater report, geotechnical engineering report, mailing labels, neighborhood meeting information, reduced size plans, application fee, and other necessary information. This application has been prepared pursuant to direction provided at a Pre -Application Conference with City staff and subsequent correspondence with City staff. All information specified on the submittal checklist is included. IV, APPLICABLE REVIEW CRITERIA CITY OF LAKE OSWEGO MUNICIPAL_ CODE CHAPTER 50 — COMMUNITY DEVELOPMENT CODE The following Articles of the City of Lake Oswego Community Development Code (LOC) have been identified by City staff and at recent meetings as being applicable to Subdivision and RP Determination. In order to conserve paper and for the sake of brevity, only those Articles that are related to the application are addressed. 1V. CHAPTER 50 — COMMUNITY DEVELOPMENT CODE LOC 50.02 BASE ZONING DISTRICTS LOC 50.02.001.1 Residential Low Density Zones LOC 50.03 USE SPECIFIC STANDARDS LOC 50.03.001.2 Residential Use Table LOC 50.04 DIMENSIONAL STANDARDS LOC 50.04.001.1 Residential Low Density Zones AKS! FREEPONS VILLAGE- SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) AIIIIIIIIIIIIIII CITY OF LAKE OSWEGO, OREGON PAGE 3 OF 48 26 LOC 50.05 OVERLAY AND DESIGN DISTRICTS LOC 50.05.010 Sensitive Lands Overlay Districts LOC 50.05.010.2 Applicability and Exceptions LOC 50.05.010.3 Development Review (See LOC 50.07.004.8) LOC 50.05.010.4 Generally Applicable Standards for RP and RC L0050.05.010.6 Standards Applicable to RP District LOC 50.06 DEVELOPMENT STANDARDS LOC 50.06.001 Building Design LOC 50.06.001.2 Structure Design LOC 50.06.002 Parking LOC 50.06.003 Circulation and Connectivity LOC 50.06.003.5 Transit System LOC 50.06.004 Site Design L0050.06.004.11 Landscaping, Screening and Buffering LOC 50.06.004.2 Fences L0050.06.004.3 Lighting Standard LOC 50.06.005 Park and Open Space LOC 50.06.006 Geologic Hazards and Drainage LOC 50.06.006.1 Weak Foundation Soils LOC 50.06.006.2 Hillside Protection LOC 50.06.006.3.b Drainage Standards LOC 50.06.007.1 Solar Access LOC 50.06.008 Utilities LOC 50.06.011.1 Vision Clearance LOC 50.07 REVIEW ANO APPROVAL PROCEDURES LOC 50.07.003.14 Minor Development Decisions LOC 50.07.004.3 Hillside Protection LOC 50.07.004.5 Local Street Connectivity LOC 50.07.004.7 Park and Open Space Contribution L0050.07.004.8 Sensitive Lands Overlay Districts L0050.07.004.11 Additional Submission Requirements (Utilities) LOC 50.07.007 Land Divisions LOC 50.07.007.2 Flog Lots LOC 50.07.007.2. e. v Setbacks LOC 50.07.007.f.i-iv Screening CHAPTER 38 -- UTILITIES CHAPTER 39 SYSTEM DEVELOPMENT CHARGES CHAPTER 42 — STREETS AND SIDEWALKS CHAPTER 55 — TREE REMOVAL AND PROTECTION CHAPTER 50 — COMMUNITY DEVELOPMENT CODE AKS� FREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 4 OF 48 27 LOC 50.02 BASE ZONING DISTRICTS LOC 50.02.001 Residential Districts 1. Residential — Low Density Zones a. Districts The residential -low density zone districts are R-15, R10, and R-7.5. b. Purpose To provide lands for single-family residential development with densities ranging from two to five dwelling units per gross acre. Response: The property is designated R-7.5 by the City of Lake Oswego Zoning Map. LOC 50.03 USE SPECIFIC STANDARDS LOC 50.03.002 Use Table 2. Residential Use Table TABLE50.03.002-1: RESIDENTIAL DISTRICTS USE TABLE P = Permitted Use J Blank = Not Permitted jxj Table notes located at the end of the toble E I E Residential Use Specific Use cat. Use Type R-15 R-10 R 23 ` R -S R-5 R -DDR -W R-3 LSj R-2 R -O L81 Standards RESIDENTIAL USES i Household Dwelling unit any type P P p Living Single-family detached dwelling pagperfat! P P P P P P [7v-03-7003 Response: This project includes the creation of 8 lots for the future construction of single family detached homes. This is a permitted use for the R-7.5 Zone as illustrated in the above table. LOC 50.04 DIMENSIONAL STANDARDS L0050.04.001 Dimensional Table Response: The following table shows the R-7.5 Zone dimensional standards and is based on LOC Table 50.04.001-1. These base zone standards apply to all of the lots in the subdivision except as superseded by the flag lot criteria in Section 50.07.007.2. The flag lot criteria will apply to all 8 lots. a. Dimensional Standards The following table shows the R-7.5 Zane dimensional standards and is based on LOC Table S0.04.001-1 to provide information for the eight proposed Lots: AjoFREEPONS VILLAGE - SUBDIVISION APPLICATION AIIIIIIIIIII CITY OF LAKE OSW EGO, OREGON 28 SEPTEMBER 2014 (UPDATED) PAGE 5 OF 46 TABLE 50.04.001-1: RESIDENTIAL LOW DENSITYZONES DIMENSIONS f1) When subdivisions are proposed, the number of lots required shall be determined by dividing the net developable acre by the minim um lot size per unit required in the underlying zone, and multiplying this number by 0.8. The result shall be rounded up for any product with a fraction of 0.5 or greater and rounded down for any product with o fraction of less than 0.5. The requirements of this section are subject to the exceptions contained in LOC 50.04.003.10, Exceptions to the Minimum Density Requirement forAll Zones. fz) Net developable acre divided by the minimum lot area per unit and rounded down to the nearest whole number. The actual density allowed on a site will be determined at the time of development review. Maximum density will be allowed to the extent that facts presented to the hearing body show that development at that density can occur within requirements set forth in the Development Standards. f31 Up to a 25% reduction in minimum required lot area for each dwelling unit shall be allowed to permit the relocation of a designated historic landmark, when relocation has been approved by the designated hearing body. Response: The subject site is zoned R-7.5. Therefore, each of the planned lots is subject to compliance with the above listed standards. All lots are planned to be configured as flag lots and are subject to the flag lot standards, which in some cases supersede the base zone R-7.5 standards. All lots are equal to or greater than 7,500 square feet. With the right-of-way vacation the gross site will contain +/- 2.189 acres or +/- 95,356 square feet. The private access lane will consist of +/-11,253 square feet. The area of the Resource Protection Area contains +/-10,346 square feet. The balance, +/- 95,356 square feet minus the private access lane and Resource Protection Area equals +/- 73,757 square feet. As mentioned in footnote 1 to Table 50.04.001-1 above exceptions to the Minimum Density Calculations can be achieved when it can be shown that the proposal meets the exception standards found in LOC 50.04.003.10. This section allows for the number of lots required to meet the minimum density provisions to be reduced when, among other circumstances, topographic, natural resources and/or soil constraints exist. Based on this information the project results in the following density calculations: FREEPONS VILLAGE — SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 6 OF 48 29 7 R-10 R-15 Comments/Additional Standards DENSITY 50.04.001.1.b Minimum LIJ 80% of max 80% of max Maximum (unitslacre) fzf [ZI MIN. LOT DIMENSIONS [3) 50.04.001.1.c Area fsq. ft.) 10,000 15,000 Width (ft.) Ali 65 80 Except PD L31 j Depth (ft.) f1) When subdivisions are proposed, the number of lots required shall be determined by dividing the net developable acre by the minim um lot size per unit required in the underlying zone, and multiplying this number by 0.8. The result shall be rounded up for any product with a fraction of 0.5 or greater and rounded down for any product with o fraction of less than 0.5. The requirements of this section are subject to the exceptions contained in LOC 50.04.003.10, Exceptions to the Minimum Density Requirement forAll Zones. fz) Net developable acre divided by the minimum lot area per unit and rounded down to the nearest whole number. The actual density allowed on a site will be determined at the time of development review. Maximum density will be allowed to the extent that facts presented to the hearing body show that development at that density can occur within requirements set forth in the Development Standards. f31 Up to a 25% reduction in minimum required lot area for each dwelling unit shall be allowed to permit the relocation of a designated historic landmark, when relocation has been approved by the designated hearing body. Response: The subject site is zoned R-7.5. Therefore, each of the planned lots is subject to compliance with the above listed standards. All lots are planned to be configured as flag lots and are subject to the flag lot standards, which in some cases supersede the base zone R-7.5 standards. All lots are equal to or greater than 7,500 square feet. With the right-of-way vacation the gross site will contain +/- 2.189 acres or +/- 95,356 square feet. The private access lane will consist of +/-11,253 square feet. The area of the Resource Protection Area contains +/-10,346 square feet. The balance, +/- 95,356 square feet minus the private access lane and Resource Protection Area equals +/- 73,757 square feet. As mentioned in footnote 1 to Table 50.04.001-1 above exceptions to the Minimum Density Calculations can be achieved when it can be shown that the proposal meets the exception standards found in LOC 50.04.003.10. This section allows for the number of lots required to meet the minimum density provisions to be reduced when, among other circumstances, topographic, natural resources and/or soil constraints exist. Based on this information the project results in the following density calculations: FREEPONS VILLAGE — SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 6 OF 48 29 The preliminary plat demonstrates that the subdivision includes 8 lots. This is less than 11 and equal to the minimum 8 lots; hence, the minimum density and maximum density standard are satisfied when an exception is granted to the minimum density as allowed by LOC 50.04.003.10. Response: Each of the lots will assume the maximum floor area per the base zoning. For a 7,500 square foot lot the base calculations would allow a maximum floor area of 3,323 square feet plus 600 square feet for a garage. Response: The above listed "base R-7.5 setback standards" apply to non -flag lots. However, all 8 lots are considered to be flag lots. The applicable yard setbacks for flag lots are discussed in this written narrative in Section 50.07.007.2 (Flag Lots). A10. . FREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) AIIIIIIIIIIII CITY OF LAKE OSWEGO, OREGON PAGE 7 OF 46 30 MAX. BASE HEIGHT f FT.J [ R 7 S R-10 R-15 structure Primary Structure R-10 R-15 22 or less Flat Lot 8 30 35 >22 to 23 Lot with Sloping Topography1 34 34 [51 35 >23 to 24p Sloped Lot 3S 35 35 >24 to 25 Response: The above listed maximum base height limitation (28 feet for flat lots) applies to non -flag lots. However, all 8 lots are considered to be flag lots. The applicable maximum height allowances for flag lots are discussed in this written narrative in Section S0.07.007.2 (Flag Lots) Maximum Cot Coverage: See LOC Toble 50.04.001-2 TABLE 50.04.001-2: RESIDENTIAL LOW DENSITY LOT COVERAGES Height (ft.) of primary Maximum Lot Coverage (%J structure H R-10 R-15 22 or less 35 35 35 >22 to 23 34 34 >23 to 24p 32 33 >24 to 25 30 32 >25 to 26 28 30 >26 to 275 27 29 >27 to 28 5 25 28 >28 to 2925 27 >29 to 30 25 25 >30 to 31 25 25 >31 to 32 25 25 >32 to 336 2S 25 >33 to 34 1G 25 25 >34 125 25 Response: Maximum lot coverage standards are based upon the height of future structures on a lot by lot basis. For the purposes of calculating the maximum lot coverage for this project, the maximum base height for all lots of 22 feet is assumed and will be addressed later under flag lot requirements. Based upon the above table, 35 percent lot coverage is allowed for all lots. FREEPONS VILLAGE — SUBDIVISION APPLICATION CITY OF LAKE OSWEGO, OREGON SEPTEMBER 2-0144 (UPDATED) PAGE 8 OF 48 31 LOC 50.04.003 Exceptions, Dimensions and Encroachments 10. Exceptions to the minimum density requirements for all zones iv. Where topographic, natural resources and/or constraints exist on site, to the extent that an applicant can demonstrate that compliance with LOC 50.06.006.2, Hillside Protection, LOC 50.05.010, Sensitive Lands Overlay District, or other soil constraints regulated by the City's Code or the State of Oregon Uniform Building Code, would preclude development such that the minimum number of lots could not be developed; Response: As illustrated by the preliminary plans, the property has topographic and natural resource constraints that exist on-site. These are located in the easterly portion of the property and generally will be included in Tract A of the subdivision. Compliance with the minimum density requirements for the project site would require a higher density than is included in the project. Incorporating additional density into the project as designed would conflict with the City requirements to protect and preserve sensitive lands because it would involve encroachment into the designated RP areas. Therefore, an exception to the minimum density is requested in this application. Detailed density calculations are provided (including the exception) previously in this narrative in response to table 50.04.001-1. LOC 50.05 OVERLAY AND DESIGN DISTRICTS LOC 50.05.010 Sensitive Lands Overlay Districts LOCS0.05.010.2 Applicability This section applies to all lands designated as RP or RC an the Sensitive Lands Map and Atlas. a. Sensitive Lands Development Review Required i. Development within: (2) The RC district or within five ft. of the RC district boundary; or (3) The construction setbacks established in LOC 50.05.010.6.c.ii(1)(e) (as shown an maps in the Sensitive Lands Atlas); shall be subject to the standards and criteria identified in LOC 50.07.004.8. c, Environmental Review. Response: The eastern portion of the site contain a City designated Class II stream corridor, W-102, designated as a Resource Protection (RP) District. The stream enters the property along the southerly boundary line and flows through an underground pipe, dissipates underground, and another stream segment re-emerges and continues to flaw in a northerly direction across the northeastern portion of the site. As shown on the preliminary plans, the entire RP area is being preserved and protected within an open space tract. Therefore, the standards of this section apply and Sensitive Lands Development review is required. [0[50.05.010.3 Development Review The development review procedures for sensitive lands overlay districts are found in LOC 50.07.004.8. Response: The RP resources were delineated on-site by SWCA Environmental Consultants. The delineation was reviewed and approved by City of Lake Oswego Natural Resource Planner Andrea Christenson. Because the resource is designated as a Class II stream corridor, a 25 foot wide riparian corridor was applied from the delineated edge of the resource and mapped. The map was provided to Andrea Christenson and she has concurred with the RP district areas designated on the map. Therefore, these requirements have been satisfied. 10� FREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) I7 CITY OF LAKE OSW EGO, OREGON PAGE 9 OF 4$ 32 LOC 50.05.010.4 Generally Applicable Standards for RP and RC b. Modifications to Dimensional Standards and Setbacks of the Underlying Zone i. Except as provided in subsections 4.b.ii and iii of this section, an applicant for development subject to environmental review may varyfrom the lot dimensional standards (building setbacks, lot size, lot width, and lot depth) otherwise applicable without a formal variance pursuant to LOC Article S0.08, Adjustments, Alternatives, and Variances, if the applicant demonstrates that: (1) Compliance with the applicable dimensional standard or standards would cause the proposed development to disrupt lands within an RP or RC district or would preclude or reduce the transfer of allowable densityfrom RP or RC zoned areas of the property to non RP or RC zoned areas; (2) The proposed development will result in greater protection of the resources identified on the site than would occur without the dimensional modification; and Response: Variances to the lot dimensional standards permitted above are not being requested. Therefore, this section is not relevant. c. Density Transfer Lot density transfer shall be permitted on residentially zoned lands subject to an RC or RP district pursuant to this section. i. Density Transfer Ratios (2) Lot density (the number of lots otherwise allowable pursuant to the underlying zoning designation but for the RC protection area) may be transferred from RC district lands to contiguous non -RC lands on the same ownership at a 1:1 ratio for the portion of the RC district which is to remain undeveloped (the protection area). Response: Although greater densities could be achieved On the site with allowable density transfers, it is not included with this application. Therefore, this section is not relevant. LOC 50.05.10.4.4 Construction Standards An owner shall submit a construction plan and narrative to the City Manager prior to any grading, clearing, or construction an a development site which contains an RP or RC district. The construction plan and narrative shop demonstrate that the following standards will be met: Response: RP district boundaries are submitted for review and approval with this application. Pending approval, the construction protection provisions will be implemented during the construction drawing permitting process. ii. RC protection boundaries and RP district boundaries, as applicable, shall be located and staked by a qualified professional prior to placement of fencing and other protective measures. Response: The RP district boundaries will be located and staked by a qualified professional prior to placement of fencing and other protective measures. iii. Hazardous Materials. The site shall be inventoried far hazardous materials, debris and noxious materials, and A� FREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) 17 CITY OF LAKE OSWEGO, OREGON PAGE 10 OF 48 33 these materials shall be removed prior to the development of the site Response: There are no known hazardous materials located on the site. If any hazardous material is found during site work it will be removed, using authorized procedures, prior to development of the site. iv. No construction, demolition, grading, or site clearing shall begin until after protective measures, signs, and erosion control measures are in place and have been inspected and approved by the City Manager and all applicable permits have been issued. Fencing and other protective measures shall not be removed, even temporarily, without the permission of the City Manager. Response: Prior to conducting construction, demolition, grading, or site clearing, protective measures will be in place and submitted for review and approval as is typical and appropriate. These plans will include appropriate measures for the protection of on-site resources as required by this section. v. No stockpiling of fill materials, or parking or storage of construction equipment shall be allowed within a resource district. Response: No stockpiling of fill material, or parking or storage of construction equipment is included within a protected resource district. Specific locations for stockpiling materials and staging for construction activity will be determined during the construction/building permit process. vi. When transportation facilities, pathways, utilities, or structures are approved within a delineated RP district, they shall be constructed in such a way that a minimum of excavation is required and so that no permanent draining or filling of a stream corridor or wetland will occur. Response: No new transportation facilities, pathways, utilities nor structures are planned within the delineated RP district. A small portion of the existing paved private driveway is located within the delineated RP district. As shown on the preliminary plans, this driveway will be removed and restored with native vegetation. This area is located above and outside the drainageway and as such will not result in draining nor filling of the drainageway. vii. Surface runoff and other water sources supplying hydrology to an RP district shall be designed and maintained so as not to adversely impact the functions and values of the resource. Response: As illustrated on the preliminary pians, sources supplying hydrology to the delineated RP district originate and are generally located off-site to the south. To the extent that on-site surface water supplies hydrology to the RP district, the project will not affect this condition as stream water run-off from new impervious surfaces will be directed towards on-site stormwater quality and detention facilities. This is described in detail in the Preliminary Stormwater Report that is included in the application materials. Please refer to the Preliminary Stormwater Report for additional information. viii. Any additional construction requirements imposed as conditions of approval or which may be required by the Development Standards, the Lake Oswego Building Code (LOC Chapter 45) or the Erosion Control Code (LOC Chapter 52). Response: The preliminary plans include a Preliminary Grading and Erosion and Sediment Control Plan and a Preliminary Tree Preservation and Removal Plan. The plans include measures necessary to satisfy the standards included in the Lake Oswego Development Code, Building Code, and Erosion Control Code. AFREEPONS VILLAGE - SUBDIVISION APPLICATION v SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 1 1 OF 48 34 LOC 50.05.010.6 Standards Applicable to RP Districts a. Resource Protection (RP) District Environmental Review Standards, Applicability and Purpose In addition to compliance with LOC 50.07.004.8.c and 50.07.004.8.d and LOG 50.05.010.4.b and 50.05.010.4.c, applicants far development that is subject to environmental review an property containing an RP district shall comply with the standards contained in LOC 50.05.010.6.b through 50.05.010.6.d, in order to., i. Prohibit new development within an RP district following delineation of the resource or resources, except as provided in this section. In the event that development is allowed within an RP district, the applicant shall mitigate for the lass of or damage to the RP resource pursuant to LOC 50.05.010.4.e through 50.05.010.4.8; Response: As shown on the preliminary plans, no new development is included within the RP district. b. RP District and Construction Setback Requirements i. The RP district shall include the delineated stream or wetland and o protected riparian area. (1) The protected riparian area contributes to the functions and values of the stream or wetlond, including: shelter, food, travel, and nesting needs of wildlife; aesthetics; surface water quality; slope stability; and flood storage. (1) The entire RP district, including the stream or wetland and its protected riparian area, shall be shown on the delineation map. Response: The RP resources were delineated on-site by SWCA Environmental Consultants. The field delineation was reviewed and approved by City of Lake Oswego Natural Resource Planner Andrea Christenson. Because the resource is designated as a Class II stream corridor a 25 foot wide riparian corridor was applied from the delineated edge of the resource and mapped. The map was provided to Andrea Christenson and she has concurred with the RP district areas designated on the map. Therefore, the entire on-site RP district, including the drainageway are shown on the preliminary plans and these requirements have been satisfied. ii. The following areas are protected riparian areas. They are measured outward from the edge of a delineated stream corridor or wetland and included in the RP district: (4) Class 11 Stream Corridors —15 ft. Response: The project site contains a Class 11 designated stream and riparian area. Based on this and the information provided above, a 25 foot wide riparian corridor is included on the preliminary plans. iii. Reduction of RP District The reviewing authority may allow the protected riparian area to be reduced when the applicant shows that: (1) The proposed development complies with L0050.05.010.4.f, Progressive Mitigation Required; and (1) The reduction in protected riparian area is not solely for the purpose of maximizing development of the site; and I�� pJ� FREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 12 OF 48 35 (3) Development abuts a Class ! or 11 Resource: Response: The applicant is not seeking a reduction to the RP district. iv. Construction Setbacks A construction setback is required from the RP district by LOC 50.05.010.6.c, onlyfor the following: (1) New structures, parking areas, active use recreation facilities, streets and driveways —ten ft. (2) Accessory structures, decks, and similar outdoor facilities meeting the criteria of LOC S0.03.004.2.b.i(1) through (3), Setback Reduction far Accessory Structures, and LOC 50.04.003.8.b, Patios and Decks — three ft. Response: As illustrated on the preliminary plans, the applicant will observe a 10 foot wide construction setback from the designated RP district areas on the site. A small segment of an existing underground waterline is located within the 10 foot wide construction setback area. As shown on the Preliminary Site and Utility Plan, this waterline is being slightly relocated. In addition, as previously described, a portion of the existing asphalt driveway is also located within a portion of the construction setback. This feature will be removed and restored with landscaping as shown on the Preliminary Landscape, Screening & Tree Mitigation Planting Plan. In addition, a soft surface pathway (a passive recreation facility) is included within the construction setback and is permitted c. RP District Development Standards i. In addition to compliance with any other applicable regulations, and subject to the requirement for compliance with subsection 6.c.iii of this section, the fallowing development, use or activity an properties containing an RP district are permitted within the RP district, subject to the standards set forth in subsection 6.c.ii of this section: (1) Landscaping; (2) Tree removal; (3) Utilities; (4) Streets, driveways, lake trams and public transportation facilities, (5) Resource enhancement projects; (6) Structures; (7) Parking areas; (8) Active use recreation facilities; (9) Hard surfaced pathways; and (10) Limited hazardous materials storage. Response: New encroachments, for any of the above listed features, are not included within the RP AFREEPONS VILLAGE-- SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY or LAKE OSWEGO, OREGON PAGE 13 OF 48 36 district. The area occupied by the existing private driveway (within the RP district) will be restored with landscaping that meets the requirements of section 6.c.ii (1)(a). iii. Land Divisions and Lot Line Adjustments The following standards apply to properties containing an RP district for applications for land divisions including partitions, subdivisions, and planned developments (PDs), and to lot line adjustments: (1) All new lots or reconfigured lots proposed an lands that include an RP district shall have designated sites for buildings that are located outside of the RP district. A lot division or lot line adjustment shall not create a lot that would necessitate, due to the presence of RP or RC resources an the created lot, an exception under LOC 50.05.010.6.d in order to site a dwelling upon the proposed lot. Response: The preliminary plans demonstrate that each new lot is located outside of the designated RP district areas. (3) Permanent signage is required in planned developments and subdivisions to identify the RP district where any common open space protects on inventoried natural resource through conditions of approval. The signage shall be installed before any occupancy permit is issued. Such signage shall be reviewed as part of the development review process, and shall meet the standards of LOC Chapter 47. Response: Identification signage will be installed for the designated RP district areas if required by the City. LOC 50.06 DEVELOPMENT STANDARDS LOC 50.06.001 Building Design 1. Applicability This section is applicable as follows: Response: The standards of this section will be reviewed at the time of the individual building permit applications for individual future homes. Therefore, to the extent that this standard is applicable, it is met. LOC 50.06.001.2 Structure Design — Residential Zones Response: The standard of this section will be reviewed at the time of the individual building permit applications for future homes. Therefore, to the extent that this standard is applicable, it is met. 4. Garage Appearance and Location for Residential Zones. Response: As mentioned in the pre -application meeting notes, this standard will be reviewed at the time of formal building permit applications for individual homes. Therefore, to the extent that these standards are applicable, they are met. LOC 50.06.002 Parking 1. Applicability �� FREEPONS VILLAGE -- SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 14 OF 48 37 The provisions of this Article shall apply to all development which generates a parking need. This shall include the construction of new structures, the remodeling of existing structures and a change of use which increases on- site parking or loading requirements or which changes access requirements. 2. Standards for Approval o. Vehicle Parking i. Required parking spaces shall be avoilable for the parking of operable passenger vehicles of residents, customers, patrons and employees and shall not be used for the storage of vehicles or materials or for the loading and unloading or parking of vehicles used in conducting the business or use. ii. Number of Required Parking Spaces The number of required parking spaces under this article shall be determined by either the Numerical Method (subsection 2.o.ii(1) of this section) or the Parking Study Method (subsection 2.o.ii(2) of this section). Response: In accordance with the requirements of this section, one off -lane parking space is required per home as well as 4 on -lane parking spaces. As illustrated on the preliminary pians, an area for at least one off -lane parking space will be provided for each of the lots in the form of private individual driveways and garages in future homes. Four on -lane parking spaces are also provided (as required by Section S0.06.003) along the Private Access Lane, or turn -around (in private easements) as shown on the preliminary plans. Therefore, the requirements of this section are met. iii. On -Site Location of Required Parking Spaces (1) All required parking shag be off-street. Parking may not be located in a required yard or special street setback except where there are specific yard setback requirements for parking established by the zone. Response: All parking required by this section is located off -lane (street). On -lane parking is also required for this project in accordance with Section 50.06.003 and is discussed in further detail below. LOC 50.06.003 Circulation and Connectivity 1. Access/Access Lanes (Flog Lots) b. Applicability This section is applicable to all major developments and to the fallowing minor developments: Easements for access Tones shall be o minimum of 20 feet wide. A minimum of 16 feet of pavement with 2 faat shoulders on each side is required for access lanes serving 5-8 dwelling units. vi. Land divisions (partitions and subdivisions) Response: This application involves a subdivision. The site will take access from the end of Cedar Street. The circulation and connectivity provisions are applicable to this application. c. Standards for Approval i. Every residentially zoned lot shall abut o street for the fallowing minimum length: AFREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 15 OF 48 38 TABLE 50.06.003-1: MINIMUM STREET FRONTAGE Residentially Zoned Lot Minimum Street Frontage Rowhouse 1 17 ft. Flag Lot L0050.07.007.2.c All Other 25 ft. Response: All of the lots are considered flag lots. As such, the standards of LOC 50.07.007.2.c will apply. Please review the preliminary plans for dimensioned frontages along the proposed Private Access Lane. U. Access design shall be based on the following five criteria: (1) Topography, (2) Traffic volume to be generated by the development; (3) Classification of the public street from which the access is taken (residential, collector or arterial), (4) Traffic volume presently carried by such street; and (5) Projected traffic volumes. Response: Access to the project site is obtained from the existing physical terminus of Cedar Street. A shared access lane is planned as described previously in the written narrative. (1) Topography is fairly level at the location of Cedar Street where the private lane will take access. The proposed grading will result in a private access lane with a 25 foot landing area with no more than a 5% grade. (2) in accordance with ITE Trip Generation Manual (9th Edition), the 7 additional homes, in addition to the home being removed, will create an average of 7 new PM peak hour trips, 5 AM peak hour trips and 67 average daily trips on weekdays. (3) Cedar Street is considered a Local 5treet. (4) Currently there are 11 driveways serving single family residences on Cedar Street east of Cornell Street. Therefore, not accounting for some trips that are generated from the south, by way of Bickner Street, an average weekday carries approximately 105 vehicle trips. (5) Since there will not bean opportunity for additional development which would utilize the proposed private access lane, no further traffic volumes at this location are projected. iii. Direct permanent access from a development to an arterial street is prohibited where an alternate access is either available or is expected to be available. A temporary access may be allowed. Response: Direct permanent access is provided for all lots by way of a shared access lane at the existing cul-de-sac terminus of Cedar 5treet. AFREEPON5 VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) ' CITY OF LAKE OSWEGO, OREGON PAGE 16 OF' 48 39 iv. Direct access from o development or a structure to a local residential street is required unless such access is not available. Response: Direct access to future homes will be provided by the shared access lane to Cedar Street, a local street. Therefore, this criterion is satisfied. v. The City may require shared access with a neighboring site or an extension of residential streets across adjacent properties to provide access to the development if necessary to prevent adverse impacts on traffic f1ow. Response: No opportunities exist for shared access from neighboring sites and the necessity of such does not exist as no adverse impacts on traffic flow are anticipated based on the existing and projected traffic volumes. vi. If no satisfactory access from a public street to a development is available, the City shall require Postponement of the development until such time as a satisfactory access becomes available. Response: Satisfactory access is provided to the site as described herein and shown on the preliminary plans. Postponement, as described above, is not relevant. vii.. Access lanes created by o partition or private streets created by a subdivision shall contemporaneously provide an option of dedication to the City. Response: The access lane can be dedicated to the City if desired by the City. d. Standards for Access lanes Access tones shall meet the following minimum standards: i. 20 foot wide easement. iii. Access to five to eight dwelling units —16 ft. of pavement with a two ft. shoulder on each side. iv. When providing access for seven to eight dwelling units, the access lane shall be designed to provide "on - lane" parking far a minimum of four standard vehicles or provide an "off -lane" parking area for a minimum of four standard vehicles. Response: The project includes a shared access lane that will provide a consolidated access for 8 future homes/lots to Cedar Street. Although, the Development Code only requires a 16 foot wide paved section with 2 foot wide gravel shoulders on either side within a 20 foot wide easement, this project is planned to include a 20 foot to 26 foot wide paved section within a 20 foot to 26 foot wide access easement for the shared access lane. A turnaround is provided at the end of the shared access lane which has been designed to accommodate firefighting apparatus. Please refer to the preliminary plans for details regarding the access lane and turnaround. A Preliminary Fire Hose Plan is included in the preliminary plans that illustrates that all portions of the ground floor of future structures on Lots 1 and 8 can be served by emergency vehicles including a fire truck. As indicated on this plan, the future homes on Lots 2-7 will be provided with automatic fire suppression sprinkler systems to satisfy Fire Marshal standards. AFREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY Or LAKE OSWEGO, OREGON PAGE 17 OF 48 40 In addition, four standard "on -lane" parking spaces are provided in easements as shown and labeled on the preliminary plans. All of these features are illustrated on the preliminary plans. These standards are met. LOC 50.06.003.2 On -Site Circulation — Driveways and Fire Access Roads a. Applicability This section is applicable to all development proposing a new use or an increased use on a site when the development will result in the construction of or the increased use of private streets, driveways, or parking lot aisles. Increased use shall be defined as an increase in trip generation or parking requirement. b. Standards for Approval i. Driveway Approaches — Locational Limitations and Restrictions (2) On corner lots where the adjacent streets are nat fully improved to their anticipated ultimate width, the nearest edge of o proposed driveway to the intersection shall be no closer than 30 ft. when measured from the lot corner, or if the corner is a radius, from the point of intersection of the tangents. If right-of-way dedication is required as o condition of approval, the lot lines after dedication shall be used as the basis for determining compliance with this standard. Response: The application does not involve any corner lots on public streets. Therefore, this standard is not relevant. (4) All driveway approaches shall be located and designed so that the driver entering or exiting the driveway can see approaching traffic for a sufficient distance to make o safe entrance and exit. American Association of State Highway and Transportation Officials (AASHTO) standards shall be used in determining compliance with this standard. Response: As shown on the preliminary plans, a shared driveway approach has been located and designed so that the driver entering or exiting the driveway can see approaching traffic for a sufficient distance to make a safe entrance or exit. (5) The maximum width of a driveway approach, measured where the edges of the driveway meet the right-of-way, shall be governed as follows: (a) Single-family residential with garage door(s) facing the street: 12 ft. per garage or carport stoll, or surface parking space, but not to exceed 30 ft. (b) Single-family residential with side -loading garage: 24 ft. (c) All other uses: 24 ft. unless otherwise justified by the recommendations of o traffic study. Response: As illustrated on the preliminary plans, the shared access lane is 20 feet to 26 feet wide. These standards do not apply to the individual driveway approaches that access the shared access lane because at no point do they meet the public right-of-way. Therefore, to the extent that these standards are relevant to the application, they are met. ii. Driveway Widths FREEPONS VILLAGE .-. SUBDIVISION APPLICATION _ SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON mm PAGE 18 OF 48 41 Driveways shall canfarm to the minimum width requirements of LOC 15.06.610 (Oregon Fire Code Adopted) and LOC 50.06.002, Parking. Response: As described above and as shown on the Preliminary Fire Hose Plan, and other plans, access to the site complies with the Oregon Fire Code. Therefore, this standard is met. iii. Driveway Grades (1) The maximum grade of a driveway serving one single-family structure shall be 20%. If the grade exceeds 15% then the residence must be provided with alternative methods far fire suppression, i.e., sprinklering. Response: As shown on the Preliminary Grading and Erosion and Sedimentation Control Plan, no portion of the shared access lane or individual future driveway serving the future homes will exceed 15%. This standard is met. (3) For oil uses except residential structures of four units or less, there shall be a landing area where a driveway used by multiple drivers meets the public street. The landing area shall be a minimum of 25 ft. long and shall have a maximum grade of 5%. The length and grade of the landing area described in this subsection presupposes that the abutting street has been fully improved to its ultimate anticipated width. If a driveway is proposed on o street that is not fully improved, and the development proposal is anticipated to proceed prior to the improvement of the street, the City Engineer shall determine the location and grade of the future street improvement and the applicant shall design the driveway and site grading so that this standard will not be compromised when the street is improved in the future. Response: As shown on the Preliminary Grading and Erosion and Sedimentation Control Plan, the shared access lane has a landing area at least 25 feet long with maximum grades that do not exceed 5%. This standard is met. (4) Along the traveled way, grade breaks shall not exceed an algebraic difference of 9% unless accomplished by the construction of o vertical curve complying with the City's Standard Details. Response: The Preliminary Grading and Erosion and Sedimentation Control Plan shows that along the traveled way, grade breaks do not exceed an algebraic difference of 9%. This standard is met. (5) The maximum cross -slope of a driveway shall be 5% except for that portion of o driveway which must blend with an odjacent street grade that exceeds 5%. When blending is necessary, the length of the blended section shall be limited to 30 ft. Response: The preliminary plans show that the shared access lane cross -slope does not exceed 5%. This standard is met. iv. Fire Access Lanes (1) All developments shall comply with the minimum requirements for fire access roads os stipulated by the Fire Code and LOC Chapter 15. Response: As described above and as shown on the Preliminary Fire Hose Plan, and other plans, access to the site complies with the Oregon Fire Code. Therefore, this standard is met. AFREEPONS VILLAGE - SUBDIVISiON APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 19 OF 48 42 (2) The paved improvement of fire lanes, their associated turnarounds and right -of- way dimensions shall comply with the City's Standard Details. Response: The shared access lane will be paved as illustrated in the preliminary plans. It will be included within a 20-26 foot wide easement as is required by the LOC and the Fire Code. Compliance with the City's Standard Construction Details will be established through the construction permit process as is customary and appropriate. This standard is met. (3) when afire access road is required to be used as a primary or alternate access route for the provision of emergency services to or through an abutting property, the fire lane shall be declared as such on o legal instrument to be recorded against the title of the affected property(ies). A declaration on a plat or an a recorded development plan may also be used to satisfy this standard. Response: All abutting properties front on existing streets. Therefore, there is no reason or need for access to abutting properties through this site. Therefore, this standard is not relevant. v. Turnarounds (11 If a dead-end driveway exceeds 150 ft. in length, it shall provide afire department turnaround in compliance with the City's Standard Details. Exception: The Fire Marshal may approve driveways greater than 150 ft. in length if the structures greater than 150 ft. from the public road are provided with alternative methods of fire suppression, i.e., sprinklering. Response: The project includes a shared access lane that will provide a consolidated access for 8 future homes/lots to Cedar Street. Although, the Development Code only requires a 16 foot wide paved section with 2 foot wide gravel shoulders on either side within a 20 foot wide easement, this project is planned to include a 20 foot to 26 foot wide paved section within a 20 foot to 26 foot wide access easement for the shared access lane. A Preliminary Fire Hose Plan is included in the preliminary plans that illustrates that all portions of the ground floor for future structures on Lots t and 8 can be served by emergency vehicles including a fire truck. As indicated on this plan, the future homes on Lots 2 through 7 will be provided with automatic fire suppression sprinkler systems to satisfy Fire Marshal standards. In addition, the turnaround at the terminus of the private access lane has been designed to accommodate firefighting apparatus as requested by the Fire Marshall. (2) Except where a continuous forward exit can be made out of the site, all developments with on-site loading and delivery areas shall provide a turnaround for delivery vehicles in compliance with the City's Standard Details. Response: The project does not include an on-site loading and delivery area. Therefore, this standard is not relevant to this application. A reasonably sized turnaround; however, is provided at the end of the shared access lane. i. All driveways that serve as fire lanes or fire access roads shall be paved, unless modified below, and shall be designed to support fire fighting vehicle loads. The City may require on engineered pavement section and a soil test to ensure compliance with this standard. AFREEPONS VILLAGE- SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE O5W EGO, OREGON PAGE 20 OF 48 43 Response: As described previously, driveways that serve as fire access lanes/roads are being paved as shown on the preliminary plans. All relevant details for the access (including structural sections) are shown on the Preliminary Site, Public Improvements and Utility Plan. LOC 50.06.003.3 On -Site Circulation — Bikeways, Walkways, and Accessways a. Applicability This section is applicable to all minor and major development involving the construction of o new structure other than a detached single family dwelling, duplex, or accessory structure, and subdivisions and planned developments. This section is also applicable to modifications which increase the square footage of commercial, industrial, public use or institutional buildings by more than 10%. For the purposes of this section, an "existing building" is a building as it exists on February 19, 1998. Response: ADA compliant bikeways, walkways, and accessways are not required for this subdivision application nor for future single-family homes. This is similar to other recent land divisions where ADA compliant pedestrian accesses were not required for single-family residential homes located on access lanes or existing public streets. Additional information regarding this topic is provided in response to Section 50.06.003 below. LOC 50.06.003.4 Local 5treet Connectivity a. Applicability This section is applicable to: i. Any development that results in the construction of a street, or ii. A land division that: (1) Is located on a parcel or lots of vacant or redevelopable land of 1.75 acres or more, Response: This project is located on a site of redevelopable land larger than 1.75 acres. Access to the project site will be provided via a shared private access easement entering from the terminus of Cedar 5treet. This section will apply. Based on the fact that all surrounding properties are developed with single family homes, a public park, or protected RP district areas, there are no opportunities for streets to be connected or extended. However, a soft surface pedestrian accessway is being provided along the east side of Lot 5 as shown on the Preliminary Subdivision Plat as well as other plans. The accessway will be 6 foot wide within a 15 foot private access easement. c. Standards for Approval of Development Which Requires the Construction of a Street L Local and neighborhood collector streets, access lanes, and residential accessways shall be designed to connect to the existing transportation system to meet the requirements of this standard as determined by the reviewing authority. ii. Local and neighborhood collector street design shall provide for full street connections between through streets with spacing of no more than 530 ft., measured between the center of the intersection of two through streets that provide far vehicle traffic movement in generally the some direction ('through street pairs') with the cross street. This requirement shall be applied to all through street pairs which surround the site. if the nearest boundary of the site for boundaries extended to the street) is more than 100 ft. from the intersection of AAFREEPONS VILLAGE--- SUBDIVISION APPLICATION mm mm SEPTEMBER 2034 (UPDATED) Crry OF LAKE OSWEGO, OREGON PAGE 21 OF 48 44 a through street nearest to the site and the cross street, the provisions of this standard shall be met, except when the provisions of subsection 4.c.vi of this section are met. See Figure 50.06.003-A: Street Connectivity. iii. Streets shall be designed to connect to all existing or approved stub streets which abut the development site. iv. Cul-de-sacs and permanent closed-end streets shall be prohibited except where (a) the requirements of this standard for street and residential accessway spacing are met and (b) construction of a through street is found to be impracticable. When cul-de-sacs or closed-end streets are allowed under subsection 4.c.vi of this section, they all be limited to 200 ft. and shall serve no more than 25 dwellings, except where the reviewing authority hos determined that this standard is impracticable due to the criteria listed in subsection 4.c.vi of this section. Response: The above listed standards would indicate the appropriateness of a street continuing through the project and either further east to Hallinan Circle or south through Freepons Park to Hemlock Street or Larch Street. However, these options are impracticable due to the existing developments and Resource Protection area to the east and the developed park to the south where adequate access is already provided. vi. The reviewing authority may allow an exception to the review standards of subsections 4.c.1 through 4.c.v of this section based on findings that the modification is the minimum necessary to address the constraint and the application of the standards is impracticable due to the following: (2) The presence of sensitive lands as described in LOC 50.05.010, or LOC 50.05.011, Flood Management Area, or other lands protected by City ordinances, where regulotions discourage construction of or prescribe different standards for street facilities, unless the nearest through street pairs (see Figure 50.06.003-A: Street Connectivity) surrounding the subject site are more than one- quarter mile apart. The reviewing authority may determine that connectivity is not required under this circumstance, if o benefit/cast analysis shows that the traffic impacts from development are low and do not provide reasonable justification for the estimated costs of a full street connection; (3) The presence of freeways, existing development patterns on abutting property which preclude the logical connection of streets or arterial access restrictions; (4) Where requiring a particular location of a road would result in violation of other City standards, or state or county laws or standards, or a traffic safety issue that cannot be resolved; or (5) Where requiring streets or accesswoys would violate provisions of leases, easements, covenants, restrictions or other agreements existing as of May 1, 1995, which preclude required street or accessway connections. Response: As stated above, the subject site includes a RP District designation that applies to +/- 10,346 square feet (+/-10.85 percent) of the subject site. The RP District designated property is part of Tract A which in total contains 19,129 square feet and extends along the entire eastern property line of the subject property. Beyond Tract "A" are existing single family homes which front on 5E Hallinan Circle. Tc the south of the subject property is the developed Freepons Park which is owned by the City of Lake Oswego. To the north of the subject property are existing homes fronting on 5W Erickson Street. Based on the above, extension of either the proposed private lane, or a public street, is not possible without impacting the RP District, the City park or the requirement of the removal of existing single family dwellings. However, a private access easement is being provided for pedestrian access to Freepons Park to the south. This will be located along the east side of Lot 5 as previously mentioned. AFREEPONS VILLAGE ^- SUBDIVISION APPLICATION SEPTEMBER 20 14 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 22 OF 48 45 viii. The reviewing authority may allow a reduction in the number of residential occessway connections required by subsection 4. c.vii of this section based on findings that demonstrate.- (1) emonstrate.(1) That reducing the number or location of connections would not significantly add to travel time or distance from the proposed development to bus lines or activity centers in the area, such as schools, shopping, or parks, or (2) That existing development patterns on abutting properties preclude logical connection of residential accessways; or (3) That the traffic impacts from development, redevelopment or both are low and do not provide reasonable justification for the estimated costs of such occessway. Response: Vehicular accessway connections through this property are not reasonable or necessary for reasons similar to those described above, which preclude the logical connection of the proposed private access lane or public street through this property. Also, any requirement to extend a public street through the property would not justify the cost of removing an existing single family dwelling and building the additional length of street necessary to make a connection. However, a private pedestrian accessway will be provided along the east side of Lot S to Freepons Part to the south. This access will consist of a 6 foot soft surface pathway within a 15 foot private easement. LOC 50.06.003.5 Transit System All applicable development as defined above shall be required to provide transit focalities and transit -oriented features. i. The extent of the transit -oriented features and transit facilities required for a particular site on a transit street shall be determined by the City, in coordination with Tri -Met, based upon an analysis of: (1) Level of existing and projected adjacent transit facilities; (2) Proximity of other ridership ottroctors, such as bus routes, (3) Size and trip generation potential of proposed development adjacent to transit street (within one- fourth mile of o transit street); and (4) Expected transit ridership generated by a development. Response: The project site is located approximately 800 feet from McVey Avenue, which is a bus route. The closest bus stop is located at the corner of the intersection of McVey Avenue and Cornell Street. These bus stops and facilities will be sufficient to handle the amount of transit ridership generated by the project. LOC 50.06.004 Site Design 1. Landscaping, Screening, and Buffering o. Applicability i. Except as provided in subsection I.a.ii of this section, this section is applicable to: FREEPONS VILLAGE ^- SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF L.AKE OSWEGO, OREGON PAGE 23 OF 48 46 (7) Subdivisions; iv. All development abutting streets shall provide street trees at the proper spacing for the species Response: As shown on the preliminary plans, street trees will be planted when homes are built on the new lots and at the proper spacing intervals along the shared access lane. 2. Fences c. Location and Height. i. Fences and walls in residential zones shall not exceed six feet in height unless otherwise provided below: (1) Four feet in height when located within ten feet of a property line abutting a public or private street or an access easement which serves more than two lots. This restriction shall not apply to properties which abut an access easement but which do not have a legal right to use the easement. For purposes of determining fence height under this subsection, alleys are not considered as public streets. Response: The erecting of fences and walls for the individual homes will be submitted as either part of their initial building permit, or a separate permit, and will adhere to City codes and standards. Potential side/rear yard fencing is shown on the Preliminary Landscape, Screening and Tree Mitigation Planting Plan. LOC 50.06.004.3 Lighting Standards a. Applicability i. This section is applicable to all minor or major development which results in increased use of public and private streets, public pathways and accesswoys, or parking lots, and lots in the Public Functions (PF) and Parks and Natural Area PF and PNA zones. Response: The lighting standards are applicable to the subdivision, which will be processed as a minor development. However, the pre -application notes found as a part of this submittal, comment on street lighting and state, "...no additional street lighting will be required for this development." Therefore, this section has been met. LOC 50.06.005 Pork and Open Space 1. Applicability I). Except as provided in LOC 50.06.005.1.b, this section is applicable to all major development, and to the following minor developments: vi. Major partitions and subdivisions. Response: This application involves a subdivision. Therefore, the requirements of this section apply. 2. Development Review The review procedures for pork and open space contributions are located in LOC 50.07.004.7, Pork and Open Space Contribution. AFREEPONS VILLAGE - SUBDIVISION APPLICATION SEI-TEM13ER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 24 OF 48 47 3. Standards for Approval a. Amount of Open Space Required iii. Subdivisions and major partitions on sites of greater than 75,000 sq. ft. in size shall provide open space approved by the City in an aggregate amount equal to at least 20% of the gross land area of the development. Response: The project site is +/-95,356 square feet (greater than 75,000 square feet) in size. As shown on the preliminary plans, the project preserves +/-19,129 square feet of land as open space. This exceeds 20 percent of the gross land area for the project and as such the application meets the 20% minimum open space requirement. a. Maintenance. i. Natural Areas. Natural areas shall remain in natural condition existing at the time of their designation, except as follows: (1) Removal of invasive plants (i.e., seethe Lake Oswego Master Plant List). (2) Removal of litter. (3) Installation and maintenance of any soft surface trails (note: see LOC 50.05.010.5.c.iii(5) and 50.05.010.6. c.ii(1)(eX►)(C)• (4) Irrigation and maintenance of trees and vegetation as necessary for their survival. (5) Planting of trees and vegetation necessary to maintain the functions and values of the natural resource, but primarily not for decorative landscaping purposes. 6) Repair of any natural waterway or wetland which is necessary to maintain the functions and values of any waterway or wetland resource within the natural area. (7) Installation of any signage that identifies or protects the natural resource, natural vegetation, and passive recreation facilities. (8) Removal of any hazardous trees, pursuant to LDC Article 55.02 (note: condition of approval may require tree to be converted to a wildlife tree). (9) Installation and maintenance of fencing that complies with the following: (a) No taller than three ft. (b) Non -sight -obscuring; and (c) No wire mesh or cyclone fence. Such fencing shall be compliant with the provisions of LOC 50.06.004.2 regarding standards for construction and standards for maintenance offences, and, if applicable, LOC 50.05.010.5 or 50.05.010.6. Response: The application involves the protection and preservation of the RP district within an open space tract. At the time of application, none of the above activities or uses are planned. However, the AFREEPONS VILLAGE -- SUBDIVISION APPLICATION W T�mmSEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 25 OF 48 48 applicant is aware of and understands these standards and will abide by them, as applicable. 5. Density Transfer a. Density Transfer Allowed Open space may be included in the net site area when determining the maximum allowable density. Structures that otherwise might have been located on open space may be transferred to other portions of the site, and lot areas may be reduced to offset for land reserved as open space, as long as the overall density remains within the maximum permitted by the zone. Response: No density transfers are proposed or required. Density is based on the portion of the property outside of Tract A. LOC 50.06.006 Geologic Hazards and Drainage LOC 50.06.006.1 Weak Foundation Soils a. Applicability This section applies in all areas identified as "Potential Weak Foundation Soils" to all. Minor and major development which will involve proposed structures, Response: This project is considered to be a minor development. Therefore, these standards are applicable. I. Weak foundation soils are identified in the "Engineering Geology" report supplement and accompanying map of the Lake Oswego Physical Resources Inventory, March 1976. ii. These soils are also identified and described in the report entitled "Soil Survey Interpretations for Land Use Planning and Community Development, Lake Oswego Area, Oregon," USDA Soil Conservation Service, December 1975. The SCS mop units which correspond to the Engineering Geology units above are listed in Table It: Characteristics and Limitations of Earth Materials, in the Engineering Geology Report of L. 0. P.R.1. Response: Per the pre -application meeting the project site may contain weak foundation soils as identified on the City's Soils map. Please see the Geotechnical Report with Infiltration Test Results, prepared by GeoPacific Engineering, Inc. The report describes the nature, distribution, and extent of the soil characteristics, including findings regarding the adequacy of the soils for the proposed use and does not indicate the presence of weak foundation soils. LOC 50.06.006.2 Hillside Protection d. Standards for Approval i. All developments on undisturbed slopes shall be designed to minimize the disturbance of natural topography, vegetation and soils. ii. Cuts and fills shall conform to the minimum requirements of LOC Chapter 45. Response: A Preliminary Grading and Erosion and Sediment Control Plan is included as part of this submittal. As shown on this plan, to the extent possible, the disturbance of natural topography, -- AFRE,EPONS VILLAGE ^- SUBDIVISION APPLICATION SEPTEMBER 2014 {UPDATED} CITY OF LAKE OSWEGO, OREGON PAGE 26 OF 48 49 vegetation, and soils is minimized. The vast majority of the trees will be preserved during the grading and utility installation for the project. 3. Drainage Standards b. Drainage Standard for Major Developments, Partitions, Subdivisions, and Certain Structures L Applicability This section is applicable to: (1) Major developments; (2) Partitions; (3) Subdivisions; and (4) Construction or alteration of structures as described in [OC 50.07.003.14.a.ii(6). Response: As this application is a subdivision, the drainage standard will apply. ii. Standards for Approval (1) Inspection and Maintenance All drainage management measures, whether located on private or public property, shall be accessible atoll times for City inspection. When these measures have been accepted by the City for maintenance, access A Standards for Approval easements shall be provided at such a width to allow access by maintenance and inspection equipment. Response: All stormwater drainage facilities will be accessible at all times for City inspection. Access easements of sufficient width to allow for City maintenance and inspection will be provided on the final plat. (2) Stormwoter Runoff Quolity All drainage systems shall include engineering design features to minimize pollutants such as oil, suspended solids, and other objectionable material in stormwater runoff. Response: As addressed in the Preliminary Stormwater Report included in the application materials, all drainage systems include engineering design features designed to minimize pollutants such as oil, suspended solids, and other objectionable material from entering into the natural drainage system. (3) Drainage Pattern Alteration Development shall be conducted in such o manner that alterations of drainage patterns (streams, ditches, swoles, and surface runoff) do not adversely affect: (a) Other properties; (b) RC districts on adjacent property; or (c) RP districts on adjacent property. Response: Drainage pattern alterations will not occur. Therefore, RC districts on adjacent properties, or RP districts on adjacent properties will not be affected. Please refer to the Preliminary Stormwater Report for additional information. (4) Stormwater Detention Sufficient stormwater detention shall be provided to maintain runoff rotes at their natural undeveloped �REEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) ' F'CITY OF LAKE OSwI;GO, OREGON _ PAGE 27 OF 48 50 levels for oil anticipated intensities and durations of rainfall and provide necessary detention to accomplish this requirement. Response: Stormwater detention is being provided through a variety of systems including vegetated planter boxes and underground detention within the proposed Private Access Lane. These detention methods will maintain runoff rates at their natural undeveloped levels. Please refer to the Preliminary Stormwater Report for details and additional information. (5) Required Stormwater Management Measures The applicant shall provide sufficient storm water management measures to meet the above stormwater runoff requirements. The applicant shall provide designs of these measures taking into account existing drainage patterns, soil properties (such as erodibility and permeability) and site topography. Response: Stormwater management is being provided through a variety of systems including biofiltration swales, subsurface detention measures, and vegetated planter boxes. These measures meet the stormwater runoff requirements. Please refer to the Preliminary Stormwater Report for additional information. fil. Standards for Construction (I) Landscaping and Topography Detention or retention areas shall, where possible, use natural topography and existing vegetation. In addition to or as replacement for existing vegetation these areas shall be landscaped with ecologically compatible trees, shrubs, and permanent ground cover. Basin or pond side slopes shall be grassed and mulched to prevent erosion. Response: The biofiltration swales and vegetated planter boxes are designed to follow natural topography where possible. Landscaping will include native plantings. Existing trees have been preserved to the maximum extent practicable. (2) Outlet Structures Outlet control structures shall be designed as simply as possible and shall require little or no attention for proper operation. Response: Please refer to the Preliminary Stormwater Report and preliminary plans for details on the proposed stormwater facilities. (3) 5ideslopes The sideslopes of oil mon-mode detention or retention basins or retention ponds shall be sufficiently sloped or treated so as not to create a safety hazard, or maintenance problem. Response: Detention for the project is being provided in 48 inch pipes located under the private access lane. Therefore, this section does not apply. (4) Emergency Overflow or Bypass All stormwoter storage areas shall be provided with some means of emergency overflow or bypass in accordance with one of the following standards: (o) Emergency Overflow An appropriate surface or subsurface drainage system shall be provided as o method of emergency FREEPONS VILLAGE- SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 28 OF 48 51 overflow in the event that a storm In excess of the 50 -year frequency storm occurs. This emergency overflow system shall be designed to function without attention and shall direct this excess flood water to an appropriate existing drainage pattern. Response: As described in the preliminary plans, and described in the Preliminary Stormwater Report, storm water will be released from the detention facility to the east and into the existing natural d rainageway. (c) Hydraulic Calculations Shall be submitted to substantiate all design features. Response: Hydraulic calculations are included in the Preliminary Stormwater Report. (5) Secondary Uses Stormwater detention or retention areas may be designed to serve a secondary purpose for recreation, open space, or other types of uses that will not be adversely affected by occasional or intermittent flooding. Response: Stormwater facilities are incorporated into the site and will accommodate other uses. Please see the Preliminary Stormwater Report for additional information and details. (6) Release Rate Outlet The outlet opening controlling the release rate of detained storm water runoff shall be: (a) Sized so as not to exceed the water conveyance capacity of the downstream drainage system; (b) Small enough to cause starmwater runoff to be detained from a storm of at least the undeveloped tenyear frequency; (c) Designed to prevent siltation or clogging of the outlet opening; and (d) Provided with a means of adjusting the size of the outlet openings. Response: Release rate outlets are appropriately designed so as to not exceed the water conveyance capacity of the downstream drainage system as required above. Please refer to the Preliminary Stormwater Report for additional information. (7) Required Detention Volume for Developments Detention volume shall be the maximum difference between: (a) The stormwater runoff produced from the proposed development site by a 50 -year storm; and (b) The starmwater runoff produced from the predevelopment site area by a ten-year storm. Response: Detention volumes are sized appropriately for this project in accordance with the above listed standards. Please refer to the Preliminary Stormwater Report for additional information. (S) Detention Basins (a) Low Flaw A positive method of carrying the low flow through detention ponds shall be provided. This method AKFREEPONS VILLAGE- SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 29 OF 48 52 shall have a positive gravity outlet to a downstream drainage system with adequate capacity. (b) Maximum Depth Maximum depth of detention ponds shall not exceed four ft. unless the existing natural ground contours and other conditions lend to greater storage depth, which may be approved by the City Manager. (c) Minimum Sideslopes The minimum sideslopes of detention ponds shall be SO to one (2%) or sufficient to ensure complete drainage of said sideslopes within a reasonable period of time. (d) Paved Areas If a portion of a detention bosin area is to be paved for parking or recreational purposes, the paved surface shall be placed at the highest possible elevation within the storage ores. Paved areas shall have minimum grades of 1 % and shall be restricted to storage depths of nine in. maximum. Response: Detention ponds are not being utilized for this project. Therefore, these sections are not relevant. (9) Retention Ponds (o) Shoreline protection shall be provided to prevent erosion from wave action. (b) The margins of all retention ponds shall be provided with an underwater shelf having a maximum slope of four to one (25%) to a depth of three ft. Other safety treatments may be allowed as approved by the City Manager. (c) To minimize growth of aquatic vegetation, the water depth beyond the underwater shelf shall be at least three to fourft. (d) If possible, a method shall be provided to drain retention ponds by gravity flow to allow cleaning and maintenance. Response: Detention and retention ponds are not being utilized for this project. Therefore, these sections are not relevant. iv. Joint Drainage Facilities Joint development of drainage facilities is encouraged, especially where individual developments cannot feasibly provide on-site facilities. The City may participate in joint drainage facilities. Response: As illustrated in the preliminary plans and as described in the Preliminary Stormwater Report, this project will utilize on-site drainage facilities. v. Detention Options Options for meeting detention requirements include on-site detention oreas, joint detention areas shared by several developers, off-site detention in City detention areas shared by several developers, off-site detention in City detention areas, or off-site detention in areas provided by the applicant. Response: As illustrated in the preliminary plans and as described in the Preliminary Stormwater Report, this project will utilize on-site drainage facilities. vi. Storm water Management Measures Examples of stormwater management measures include: French drains, porous pavement, precast concrete lattice blocks and bricks, grass lined channels, dry wells, seepage ditches, and detention areas. Response: This development includes biofiltration swales, vegetated planter boxes, and an underground detention area. Please refer to the preliminary plans and Preliminary Stormwater Report for additional FREEPONS VILLAGE -- SUBDIVISION APPLICATION SEPTEMBER 2-014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 30 OF 48 53 information. LOC 50.06.007 Solar Access 1. Solar Access for New Development b. Applicability The solor design standard in LOC 50.06.007.I.d shall apply to applications for o development to create lots in the R-7.5, R-10 and R-15 zones and for development which creates lots intended for single family detached dwellings in any zone, except to the extent the hearing body finds that the applicant has shown one or more of the conditions listed in LOC 50.04.004.1, Exemptions from Solar Design Standard, and LOC 50.04.004.2, Adjustment to Solar Design Standard, exist and exemptions or adjustments provided far therein are warranted. Response: This application includes the creation of 8 lots through a subdivision in the R-7.5 Zone that are intended for single family detached dwellings. Therefore, these standards apply to this application. d. Solar Design Standard At least 80% of the lots in a development subject to this section shall comply with one or more of the options in this section. In order to be included in the 80% requirement a lot must also comply with LOC 50.06.007.1.e. i. Basic Requirement A lot complies with this section if it: (1) Hasa north -south dimension of 90 ft. or more; and (2) Hasa front lot line that is oriented within 30° of a true east -west axis. Response: Each of the 8 lots will meet the standards of this section. This will result in 100% of the lots meeting the basic requirement. Therefore the project meets the Solar Design Standard. LOC 50.06.008 Utilities 1. Applicability All development requiring connection to utilities. Response: The project will connect to basic City of Lake Oswego utility services as shown on the preliminary plans. 2. Development Review The review procedures for utilities are located in LOC 50.07.004.11, Utilities. Response: The applicant is aware of the review procedures for utilities and the preliminary plans were designed in accordance with this process. 3. Standards for Approval a. Utilities Required The following utilities, whether on or off site, sholl be provided to all development in the City of Lake Oswego, in accordance with City engineering division's policies, design standards, technical specifications and standard details: L Sanitary sewer systems fl. Water distribution systems FREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 31 OF 48 54 iii. Sidewalks and any special pedestrian ways and bicycle paths iv. Street name signs v. Traffic control signs and devices vi. Street lights, which shall be served from an underground source of power vii Underground utility and service facilities, as required vili. Streets ix. Provision for underground T. V. cable The City Manager may require that utility designs be prepared by o registered engineer. Response: All utilities noted in this section will be provided to the subdivision. Sewer and water, sidewalks, street name signs, traffic control signs, underground utilities and street design all fall under the utility definition. These utility elements are included in the preliminary plans. City engineering staff has determined that public facilities will have the capacity to serve the eight lots included in this subdivision. As indicated by City Engineering staff, there is an existing 8 inch public sanitary sewer located in Cedar Street that currently terminates with a manhole in front of 1004 Cedar Street. The project will be designed so that all sanitary sewer service will connect into that existing line. Also, all of the project will be able to utilize the existing 10 inch water line within Cedar Street. This water line currently extends along the northern property line of the subject property but will be relocated within the private access lane and portions of the existing line will be abandoned. City staff has also indicated that street lighting is not required as part of this project. b. Easements or right-of-way for utilities and associated and related focilities shall be provided by the property o wner. Easements for onticipated future utilities or extensions may be required by the City Manager. Response: All necessary utility easements are shown on the preliminary plans and will be provided recorded as part of the Final Plat. c. Sanitary sewers shall be installed to serve the development and to connect the development to existing mains. Response: As indicated by City Engineering staff, there is an existing 8 inch public sanitary sewer located in Cedar Street that currently terminates with a manhole in front of 1004 Cedar Street. That line will extend within the private lane in order to provide service to all lots included in the project. d. Design shall take into account the capacity and grade to ollow for desirable future extension beyond the development, and where required by the City Manager, extended to the upstream property line to allow forsuch future extension. Response: As the site is surrounded by existing development, future extensions beyond this site are not considered. e. All sanitary sewers and appurtenant structures shall be designed and constructed in conformance with City Engineering Division's policies, design standards, technical specifications and standard details, and shall include, but not be limited to, such items as: i. Pipe size and materials; ii. Manholes, ill. Cleonouts; iv. Backfill requirements; v. Service laterals. AFREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (LIPDATFD) CITY OF LAKE OSWEGO, ORFGON PAGE 82 OF 48 55 Response: All sanitary sewers and structures will be designed and constructed in conformance with City Engineering Division policies and standards. f. All development shall be served by service lines, main water lines and fire hydrants which are connected to City mains or the water mains of water districts which provide service within the City. Response: As mentioned in the pre -application comments from City staff, the City of Lake Oswego owns and maintains a 10 inch water main in Cedar Street and along the northern boundary of the site, where it reduces down to an 8 inch main northeast of the site and connects to the main in Hallinan Circle. There is also an 8 inch public water main located in Bickner Street which completes a loop system in Spruce Street and Cedar Street. Individual private water services shall be provided to each lot from the existing mains. The water meters shall be located within a public utility easement. The closest fire hydrant is located in front of 1002 Cedar Street. Based on staff comments from the Fire Department, fire flow for fire protection is adequate. In addition, homes on Lots 2-7 will be equipped with automatic suppression systems as required by Fire District Standards. g. Design of water system improvements shall take into account provision for extension beyond the development to adequately grid or loop the City system. Response: As the site is surrounded by existing development, the design of the water system does not take into account future extension beyond the project site. h. One water service line shall be provided to each lot in a development, or if the development does not include lots, to each building in the development. Each structure with plumbing shall connect to the water system. The system sholl be designed to supply fire flow requirements of LOC Chapter 45. Response: Each of the 8 lots will be provided a water service line from the main line being extended within the private lane from Cedar Street. The lines will be designed to provide adequate flow and pressure to meet the requirements of LOC Chapter 45. 4. Standards for Construction a. Utility easement widths shall be the minimum width possible to facilitate utility installation and maintenance, and shall be a minimum of ten ft. (five fi on each side) in width on easements not adjacent to a street right-of-way. Response: Utility easement widths shown on the Preliminary Subdivision Plat will be adequate to meet the standards of this section. b. Utility construction within easements shall minimize disturbance to existing conditions, especially trees and other vegetation. Reponse: Utility construction within easements will minimize disturbance to existing conditions, especially trees and other vegetation. c. Any disturbed areas within easements shall be restored to a condition similar to the condition prior to construction, including the replacement of plants of similar species as those removed or damaged. Replacement trees shall be of similar species and be a minimum of one and one-half in. caliper. Response: Any disturbed areas within easements will be restored to a condition similar or better than AFREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 33 OF 48 56 pre -construction conditions. d. Utilities shall be installed underground (unless exempted by the City Manager). Response: The utilities proposed with this subdivision are shown on the preliminary plans and will be constructed in accordance with the above criteria. Final construction plans will be prepared by a licensed professional civil engineer, submitted to, reviewed, and approved by the City prior to construction of the improvements, as is appropriate and required. e. Sanitary Sewers. Capacity, grade and materials shall be as approved by the City Manager. Minimum size shall be eight in. diameter with six in. diameter allowed at the terminus of a sewer line. Response: Sanitary sewer main extensions will meet this requirement. f. All sanitary sewers and appurtenant structures shall be designed and constructed in conformance with City Engineering Division's policies, design standards, technical specifications and standard details, and shall include, but not be limited to, such items as: L Pipe size and materials; if. Manholes; iii. Cleanouts; iv. Backfill requirements, v. Service laterals. Response, All sanitary sewers will be designed and constructed in conformance with the City Engineering Division's policies and design standards. g. Service Laterals. One service lateral shall be provided to each lot in a development, or if the development does not include lots, to each occupied building in the development. Response: One service lateral will be provided to each lot in the proposed development as indicated on the Preliminary Site, Public Improvements, and Utility Plan. h. Design, including materials, size and location of water mains, service lines, valves and hydrants, shall be in occordance with City Engineering Division's policies, design standards, technical specifications and standard details and be approved by the City Manager. Hydrants shall be located at intersections and of intervals of no more than 500 ft. from intersections in major developments with the exception that multi family units shall locate a hydrant within 500 ft, of residential buildings. For major or minor partitions which creote a new lot or lots, a hydrant shall be no farther than 1,000 ft. from any of the lots. Response: The City of Lake Oswego owns and maintains a 10 inch water main located in Cedar Street and along the northern boundary of the site, where it reduces down to an 8 inch main northeast of the site and connects to the main in Hallinan Circle. There is also an 8 inch public water main located in Bickner Street which completes a loop system in Spruce Street and Cedar Street. Individual private water services shall be provided to each lot from the existing mains. The closest fire hydrant is located immediately across Cedar Street from the site. Final design will be in accordance with City of Lake FREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2-014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 34 OF 48 57 Oswego policies. i. All facilities as described in this section shall be constructed in compliance with the rules and regulations of the City Manager, and the rules and regulations of the Public Utility Commissioner of the state relating to the installation and safety of underground lines, plant, system, equipment and apparatus. Response: All facilities will be constructed in compliance with the rules and regulations of the City Manager and the Public Utility Commissioner of the State. 5. Standards for Maintenance Response: Facilities will be maintained according to City standards. 6. Cost of Improvements The cost of oil utility improvements shall be borne by the developer. Response: The applicant is aware that the cost of all utility improvements will be borne by the developer. LOC 50.06.011.1 Vision Clearance 1. Vision Clearance Triangle The "vision clearance triangle" is that area enclosed by the lines formed by the outside edges of the intersecting pavements or driving surfaces and a straight line drawn diagonally across the corner, connecting those lines at the various distances specified below. The measured distance along the povement is the "vision clearance distance". Measurement shall be from the point of intersection of the traveled surfaces. 2. Standards a. Prohibited items in Vision Clearonce Triangle Within the vision clearance triangle, it shall be unlowful to install, set out or maintain, or to allow the installation, setting out or maintenance of, any sign, fence, hedge, shrubbery, natural growth or other obstruction to the view, higher than 30 inch above the level of the centerline of the adjacent pavement Response: As indicated on the preliminary plans, vision clearance triangles are located at the end of Cedar Street, at the intersection with the project access drive. The applicant is aware that this area shall be clear of shrubbery and obstructions. Additional vision triangles will be provided for each lot as the driveway locations are established and will be submitted as part of the building permit application for each lot. b. Dimensions The dimensions of the vision clearance triangle, as measured from the point of intersection of the traveled surfaces, shall be as follows: iv. At an intersection of o driveway and o street, the vision clearance distance along each traveled surface shall be 10 feet. Response: As illustrated in the preliminary plans, the required vision clearance triangles are provided at the intersection of the shared access lane at the end of Cedar Street, A&S. FREEPONS VILLAGE — Sui3mvisiON APPLICATION SEPTEMBER 2014 (UPDATED) MIIIIIIIIII CITY OF LAKE OSWEGO, OREGON PAGE 35 OF 48 58 LOC 50.07 RE'VIE'W AND APPROVAL PROCEDURES LOC 50.07.003.14 Minor Development Decisions a. Minor Development Classification i. A minor development is a development which requires a permit from the City that requires a more discretionary level of review than a ministerial decision. "Minor development" is intended to include decisions defined as 'limited land use decisions" pursuant to ORS 197.015(12). (9) Subdivisions (with or without a planned development overlay) (20) Delineation of on RP district Response: This application includes a subdivision and an RP district delineation. Therefore, the standards of this section will apply. d. Review and Decision: il. A minor development shall comply with: (1) The requirements of the zone in which it is located; (2) The development standards applicable to minor developments; (3) Any additional statutory, regulatory or Lake Oswego Cade provisions which may be applicable to the specific minor development application, as provided far in this Community Development Cade (LOC Chapter 50), streets and sidewalks chapter (LOC Chapter 42), and the tree cutting chapter (LOC Chapter 55); and Response: This written narrative, together with the preliminary plans and other accompanying documentation demonstrates that the requirements of the R-7.5 Zone are met. All applicable standards and Lake Oswego Code provisions that are relevant to a minor development are addressed in this narrative and compliance is demonstrated in the preliminary plans and other documentation included in the application materials. LOC 50.07.004.1 Drainage Standards a. Submissions for All Development For all applicable development or construction, the applicant shall submit information regarding existing drainage systems, starmwater runoff under existing and proposed development site conditions, and the effect of site runoff an adjoining properties. Such information includes: i. General Information Information concerning clearing, grading, vegetation preservation, and drainage improvements. ii. Hydraulic Characteristics When a watercourse is present an the site, information regarding its hydraulic characteristics shall be submitted. Response: These items have been addressed with the preliminary plans and Preliminary 5tormwater Report included with this application. AFREEPONS VILLAGE - SUBmvISiON APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSW EGO, OREGON PAGE 36 OF 48 59 LOC 50.07.004.3 Hillside Protection a. Submission Requirements For all applicable development or construction, the applicant shall submit the following: I. Survey Required Response: A survey of the site topography and property boundary is included in the preliminary plans. L Grading Plan Required ii. For oil development proposed on land with undisturbed slopes greater than 20%, a specific grading plan shall be provided and approved which shows all proposed changes in natural terrain. Response: No development has been proposed on slopes greater than 20%. A Preliminary Grading and Erosion and Sediment Control Plan has been included with the preliminary plans. This plan includes the information referenced above. LOC 50.07.004.5 Local Street Connectivity o. Submission Requirements For all applicable development or construction, the applicant shall submit: i. Proof of notification of o circulation analysis pursuant to this subsection and subsection 5.a.ii of this section, to all property owners within 530 ft. of the boundaries of the parcel on which a development or construction is proposed, if any future streets or accessways are proposed beyond the boundaries of the subject parcel. Notification shall be in o form substantially similar to the example provided by the City. Notification shall be sent to the applicant and the owners of record on the most recent property tax assessment roll as stated above, in the manner required in LOC 50.07.003.3.e, Notice for Public Hearing. Response: A circulation analysis (Preliminary Connectivity Plan) is included in the application material. The plan demonstrates that future street are not planned beyond the boundary of the project site. However, a pedestrian accessway will be provided along the east edge of Lot 5 where a 6 foot soft surface pathway will be installed within a 15 foot private easement for the benefit of all lots to access Freepons Park. Therefore, this requirement is met. ii. A circulation analysis, which includes o scaled site plan showing of o minimum: (1) The subject site and the entirety of oil properties within 530 ft. of the parcel on which the development or construction is proposed; (2) A scaled site plan showing existing and proposed topography with contour intervals not more than five ft.; (3) Drainage features, floodplalns, and existing natural resource areas and significant vegetation, (4) The name, location, right-of-way, pattern and grades of oil existing and approved streets bikeways and pedestrian ways, (5) Proposed streets and bike or pedestrian facilities identified in the Transportation Improvement Program in the Comprehensive Pion or applicable neighborhood plans; FREEPONS VILLAGE - SUBDIVFSION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 37 OF 48 60 (6) All permanent structures; (7) Property lines; (8) Bus lines or activity centers, such as schools, shopping or parks, within one-quarter mile (1,320 ft.) of the site; and (9) All streets and residential accessways proposed by the opplicant, containing sufficient dimensions, spot elevations, existing structures and land features on the subject site and abutting lots, to demonstrate compliance with this standard. The circulation analysis shall graphically and textually illustrate how the proposed development or construction complies with this standard. The applicont must illustrate how proposed streets and residential accessways will provide connections to surrounding properties within 530 ft. of the subject site or to the nearest through street pairs, whichever is closer, in compliance with this standard. Response: A Preliminary Connectivity Plan is included in the application materials. The plan shows the proposed soft surface pathway that extends from the end of the Private Access Lane along the east side of lot 5 and to the northern edge of Freepons Park. Therefore, this submittal requirement is met. LOC 50,07.004.7 Park and Open Space Contribution a. Application Development applications shall include a scaled plan which identifies the site's proposed open space. Response: The application includes preliminary plans identifying open space. Approximately 19,129 square feet will be designated as open space. b. Identification on Plat or Development Plan Open space land shall be clearly and accurately depicted an the final plat map or development plan and documented in the development permit record. If not dedicated by plat and the land is to be in public control, the conveyance shall be by document acceptable inform to the City Attorney. Response: As shown on the preliminary plans, open space will be dedicated through Tract A in the amount of+/- 19,129 square feet. c. Priority Open Space Areas Lands shall be selected by the City for reservation as open space areas in accordance with the following priorities: i. Delineated RP resources Response: The project site includes RP delineated resources. As discussed in section LDC 50.05.010.3, the open space area is adjacent to Freepons Park to the south and will provide excellent open space connectivity and tree and natural resource preservation. Approximately 19,129 square feet of open space will be provided as Tract A. d. Review and Decision FREEPONS VILLAGE ^ SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 38 OF 48 61 i. The decision on whether land is acceptable by the public for control and maintenance for open space purposes is to be made by the City Manager at the City Manager's discretion. Formal acceptance of open space lands shall be by City Council resolution. Lands may be approved by the City to be counted toward meeting the open space requirement that are not acceptable to the City for public control and maintenance. ii Final approval of open space boundaries shall be made by the hearing body of the time of the public hearing on the development proposal Response: The application includes scaled plans that identify the project open space as required by LOC 50.07.004.7. The applicant understands and is aware of these requirements. a. Granting of Partial Rights to Open Space Lands Up to 10096 of the open space requirements may be met by the granting of partial rights or reservations, such as: ii. Imposition of deed restrictions such as tree cutting restrictions in yards or special setback requirements. Response: Open space lands are being provided through designation of an open space area, referred to as Tract A, at ±19,129 square feet. No deed restrictions are planned for tree cutting on individual lots. LOC 50.07.004.8 Sensitive Lands Overlay Districts c. Environmental Review An applicant for a development subject to LOC 50.05.010.2 shall comply with: i. For exempt development under LOC 50.07.003.12 occurring within on RC or RP district or its associated construction setback, the applicant shall. (1) Comply with the applicable RP district or RC district development standards (LOC 50.05.010.5.c or LOC 50.05.010.6.c); (2) Comply with the Construction Standards (L0050.05.010.4.d) to the satisfaction of the City Manager; (3) Meet the steps of avoidance and minimization as stated in LOC 50.05.010.4.f; and (4) File a mitigation plan that complies with the standards of LOC 50.05.010.4.g for the review and approval of the City Manager. Response: Information required for environmental review by Chapter 50.05.10 is included in the application narrative. This is as described in the written narrative and illustrated on the preliminary plans. The RP district standards, construction standards, and avoidance and mitigation measures are fully addressed, as applicable, in the corresponding portion of the written narrative. Please review the preliminary plans sheets for further information. d. Delineation of Streams, Wetlands, and Tree Groves Response: The subject property contains sensitive lands in the form of a stream and riparian corridor. In May 2014, 5WCA Environmental Consultants delineated two distinct RP areas on site. City of Lake Oswego Natural Resources Planner Andrea Christenson verified and concurred with the delineated resources. The delineated resources are shown on the preliminary plans included with this application. Lake Oswego has two stream and wetland classifications: Class I, which has a protected riparian area of AFREEPONS VILLAGE --• SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE $9 OF 48 62 30 feet, and Class II, which has a protected riparian area of 25 feet. (See L0050.05.010.6.b.) The stream located on the project site is a Class 11 stream. Therefore, the protected riparian area for this stream is 25 feet from the top of slope, as well as a 10 -foot construction setback. LOC 50.07.007 Land Divisions LOC 50.07.007.2 Flag Lois c. Access i. When creating flag lots, the reviewing authority shall require that access to the flag lots is consolidated into a single shared access lane with occess to the parent parcel or off-site, wherever practicable. if not practicable, then an additional access may be allowed on-site or off-site. Access lanes shall extend through the partition site and be extended to abutting developable property to provide a continuous connecting access lane where practicoble. Response: As illustrated on the preliminary plans, a single shared access easement is provided to access Lots 1-8. This easement, which starts in the northwestern portion of the project at the end of Cedar Street, continues south and east through the project and provides a shared access for to all proposed lots. The pavement width varies from 20-26 feet within the 20-26 foot wide access easement. The subject site is surrounded by existing development, a city park, and natural resources. Therefore, extension of the access lane to off-site properties is not practicable. H. Flag lots shall have access to a public or private street; however, actual street frontage shall not be required. Response: As shown on the preliminary plans, all lots will have access to Cedar Street, by way of the Private Access Lane. Public street frontage is not provided nor required for flag lot. X. A driveway sholl be used to serve a single property. An access lane shag serve no more than eight properties. Response: The access lane will serve eight properties, which is no more than allowed. This is consistent with the purpose of this section. (1) Driveway widths sholl be a minimum of 12 ft. Driveway length, construction standards, and turnaround requirements shall be determined by LOC 50.06.003.2, On -Site Circulation — Driveways and Fire Access Roads. (2) See LOC 50.06.003.1.d, Standards far Access Lanes, for width of access lanes. Response: As illustrated on the preliminary plans, a 20-26 foot wide paved access lane (within a 20 -- 26 foot wide easement) will serve all lots. This complies with the standards listed in LOC Article 50.06.003.1.d. iv. No more than two driveways or access lanes shall be permitted within a distance equal to the minimum lot width of the underlying zone, or within SO ft. of each other if no minimum exists, as measured from the closest edge of each drive woy or access lone. Response: As illustrated on the preliminary plans, there are no more than two flag -lot driveways or access lanes within 50' (the minimum lot width of the R-7.5 zone) in this situation. Therefore, this standard is satisfied. FREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 40 OF 48 63 v. All buildings on flog lots must post an address at the beginning of the driveway or access lane. The address shall be no less than six inches tall, must be an contrasting background, plainly visible, and must indicate the direction to the building. Response: The site addresses will be posted at the beginning of the access lane, as required above. d. Lot Configuration Requirements i. Determination of Front Yard The front yard shall be determined as fallaws: (1) Except for a lot that fronts on a public street, the front yards) of a flag lot shall be measured from the access lane ar from a projected extension of the access lane through the property (see LOC 50.07.007.1.e.v for setback requirements). (2) A front yard occurs on either side of the access lane of the flag lot. See Figure 50.07.007-A: Flag Lot Front Yard. Response: The front yard for each lot is shown on the preliminary plans. In no instance do any lots have frontage on more than one access lane so there is only one front yard for each lot. ii. Lot Width Lot width shall be measured by a line connecting two points an opposite side yard property lines, that will result in a line parallel to the front yard. Response: As shown on the Preliminary Subdivision Plat, the width for each lot exceeds 50 feet in width, the R-7.5 standard for flag lots. ii. Lot Size Area of access easement or flagpole shall be deducted from the gross acreage of the flag lot. The ' flag" portion of the lot shall be equal to or exceed the square footage of the underlying zone. Response: As shown on the Preliminary Subdivision Plat, each of the lots is equal to or exceeds 7,500 square feet, the R7.5 standard for flag lots. e. Building and Site Design Standards i. Building Orientation The reviewing authority shall require the following: (1) New dwellings an flag lots shall have the front of the house oriented towards the access lane or from a projected extension of the access lane through the property. Response: Future houses on the lots will be oriented towards the access lane as shown on the preliminary plans. Further review and approval of a future residence's orientation by the City will occur at the time of the building permit application. Therefore, this standard is met. iii. Maximum Structure Height The height of a single-family residential structure and any accessory structures on a flag lot shall not exceed: -- A FREEPONS VILLAGE - SUBDIVISION APPLICATION YSEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 41 OF 48 64 (1 ) For flag lots created ofter August 14, 2003, the taller of.• (a) 22 ft., or (b) The average height of all dwellings on properties abutting the development site, as determined prior to the time of creation of the flag lot. Where there is no dwelling on the abutting property or where a dwelling is located more than 100 ft. away from the development site, then the maximum height permitted in the underlying zone shall be used for calculating the average. In cases where the abutting property is zoned to permit a height greater than that allowed on the subject site, then the maximum height for the zone in which the subject site is located shall be substituted and used to calculate the average. Response: A survey of the surrounding existing dwelling heights is included in the preliminary plans. This survey demonstrates that there are 11 properties abutting the subject site. Details concerning this survey are as follows: 1. Tax Lot 6600 — Building height: 20.3 feet 2. Tax Lot 6000 — Building height: 21.3 feet 3. Tax Lot 5900 — Building height: 15.8 feet 4. Tax Lot 3000 — Building height: 14.6 feet 5. Tax Lot 3100 — Building height: 18.2 feet 6. Tax Lot 3200 — Building height: 18.2 feet 7. Tax Lot 4700 — Vacant—Allows 28.0 feet 8. Tax Lot 4701— Vacant—Allows 28.0 feet 9. Tax Lot 4900 -- Building height: 19.6 feet 10. Tax Lot 5000 — Building height: 28.0 feet 11. Tax Lot 5101— Vacant—Allows 28.0 feet Based upon the above, the average height of all dwellings on properties abutting the subject site is 21.8 feet. This includes three vacant adjacent lots where 28.0 feet is used as allowed by Code. This results in the maximum height for any structure on the lots to be 22 feet. iv. Access Lane Siting The access lane shall be located no closer than five ft. to any existing dwellings Response: As shown on the preliminary plans, the existing dwelling will be removed. Therefore, this standard is satisfied. v. Setback Requirements (1 ) The standard front yard setback of the zone shall be superseded by the following front yard requirement: A minimum ten ft. front yard setback is required from the access lane, except that a 20 ft. setback is required from the access lane to the front of a garage or carport when the garage or carport opening faces the access lane. For purposes of this standard, the access lane shall include the projected extension of the access lane through the property as illustrated in Figure 50.07.007-8: Access Lane. Response: Setbacks for future structures are shown on the preliminary plans and meet the above Al FREEPONS VILLAGE — SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OswEGO, OREGON PAGE 42 OF 48 65 standards for flag lots. (2) Where a flag lot abuts a lot in o residential district of lower density, the greater setback requirements of the more restrictive district shall apply for those yards which have abutting property lines. Response: None of the lots abut a lot in a residential district of lower density. Therefore, this section does not apply. (3) The side and rear yard setbacks shall be established at the time of flag lot creation, subject to the following requirements: (a) The sum of the side and rear yard setbacks on flag lots shall be not less than: (h) 45 ft. in residential zones other than R-10 and R-15. (b) In applying the flexible standard, provide yard dimensions that are similar to the yard dimensions of primary structures on abutting properties that are not part of the partition site and that abut the rear or side yards of the flag lots, but in no event shall the rear or side yard established under this section be less than ten ft. Response: Setbacks for future buildings are shown on the preliminary plans and abide by the required side and rear yards as allowed in this section. vL Lot Width Requirement The /at width dimensions of a flag lot shall not be less than the minimum lot width requirement of the underlying zone. Response: As shown on the Preliminary Subdivision Plat, the width for each lot exceeds 50 feet in width, the R-7.5 standard for flag lots. f. Screening, Buffering and Landscape Installation L A minimum five ft. landscape strip shall be provided abutting both sides of the access lane serving flag lots except for pedestrian and vehicle access to the flag lot(s) served by the access lane. Where land area is not sufficient to accommodate a five ft. wide landscape strip on either side of the new access lane, the review authority may impose conditions of approval to include measures that will provide effective buffering and screening. These measures may include landscaped islands, fencing, and meandering access lane. The reviewing authority shall require the landscape strip to be planted with trees and shrubs in order to mitigate the visual impact of wide expanses of pavement, and to provide a visual buffer between the access lane and the affected dwellings) located on abutting lots. Plant materials used for screening and buffering shall be of a size to provide an effective screen within two years of planting. Trees shall be a minimum two in. caliper, and shrubs shall be a minimum of five gallon at time of planting. Maintenance of the buffer is an ongoing obligation of the property owner. Response: As illustrated on the preliminary plans, a landscape strip is included along the access lane in locations and in a manner where it can be safely provided. H. Existing mature vegetation and trees shall be integrated as screening where practicable. The review FREEPONS VILLAGE -SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 43 OF 48 66 authority may require dwelling and garage placement or orientation in a manner that will minimize the removal of specific trees, hedges, or other vegetation that would serve to screen the proposed structures from existing and potential surrounding homes. Response: The location of future dwellings or garages will not affect any existing mature vegetation. As illustrated on the Existing Conditions Plan, the location of existing mature vegetation is found mainly in the eastern and northeastern portions of the property within the Resource Protection (RP) district. As illustrated on the Preliminary Tree Preservation and Removal Plan only three trees are proposed for removal in this area. Another area of high tree concentration is found in the southwest corner of the site which is in close proximity to adjacent properties and not in a location where future dwellings or garages would be built. None of the trees in this location are shown to be removed. Other trees which are outside of the RP district, and not located along the outer edges of the property, are being removed to accommodate the required grading for the access lane. However, these trees are mainly English Holly or fruit trees and are part of the landscaping around the existing house. Some of the trees removed by the grading are classified as invasive species trees or hazardous trees. iii. The rear and side yards of the lot where the new development occurs shall be screened from adjacent property with a six ft. tall fence, except where o four ft. fence is required by LOC 50.06.004.2.c.i, Fences, and except where the abutting property owner agrees in writing that o fence is not necessaryalong the common property line. In addition, a landscaped buffer within the rear yard setback a minimum of six ft. in width shall be created along the rear property line and planted with a deciduous or evergreen hedge, a minimum four ft. in height of planting which shall grow to a height of six ft. within two years and shall be maintained at a minimum of that height, except where the abutting property owner agrees in writing that a landscaped buffer is not necessary. The above requirements pertoining to the "rear yard" are not applicable where the rear yard abuts Oswego Lake. Response: As illustrated on the preliminary plans, the rear and side yards of the future lots abut a number of off-site properties. This includes properties also owned by the land owner and/or applicant (Tax Lots 5000 and 5101), a City owned park (Tax Lots 4700 and 4701), and three other off-site properties (Tax Lots 4900, 6000, and 6500). As stipulated above, screening is not required where the owner of abutting property does not desire the screening. The locations of and details for these screening and buffering areas are illustrated on the Preliminary Landscape, Screening, and Tree Mitigation Planting Plan. CHAPTER 38 - UTILITIES Response: The following is a general list of utilities included with the project. Details regarding these improvements have been provided previously in this written narrative. • Water • Sanitary • Sewer • Franchise Utilities • Power CHAPTER 39 -- SYSTEM DEVELOPMENT CHARGES Response: The applicant understands that the City will assess SDCs at the time of issuance of individual building permits forfuture homes. � Aj FREEPOMS VILLAGE - SU13DIVISION APPLICATION SEPTEMBER 2014 (UPDATED) AIIIIIIIIIIII 67 CITY OF LAKE OSWEGO, OREGON PAGE 44 OF 48 67 CHAPTER 42 - STREETS AND SIDEWALKS 42.03.015 -application All street improvements within the jurisdiction of the City of Lake Oswego shall be governed by the provisions of LOC Article 42.03 and the provisions of LOC Chapter 50 Response: As shown on the preliminary plans, the property fronts Cedar Street. Final design and construction of required improvements will adhere to City codes and standards, and all necessary permits will be acquired prior to construction. 2. New development required by a development permit issued under LOC Chapter 50 to make street and frontage improvements shall do so consistent with the standards of this Article. Response: As illustrated in the preliminary plans, the project includes removal, replacement and restoration of a portion of Cedar Street that provides access to the property. This includes from the existing physical street terminus to the west, a linear distance of slightly over 300 feet. This is consistent with discussions with City staff at the pre -application conference. CHAPTER SS -•- TREE, REMOVAL AND PROTECTION 55.02 TREE REMOVAL LOC 55.01.035 Tree Removal in Conjunction with Major or Minor Development Permit. 1. If a Major or Minor Development Permit applied for pursuant to LOC 50.07.003.15 or 50.07.003.14. respectively, would require or result in tree removal and/or a tree cutting permit as defined in this Chapter, compliance with LOC 55.02. 080 shall be a criterion of approval of such development permit. Tree removals in conjunction with a Major or Minor Development Permit shall be considered in conjunction with such permit and shall be subject to the application, notice, hearing and appeal procedures applicable to the proposed Major or Minor Development pursuant to LOC 50.07.003.3.e, 50.07.003.7.x, 50.07.003.15.b, and 50.07.003.7. The required Notice for Major or Minor Developments that would require or result in tree removals shall include a site plan indicating the location of any trees proposed for removal on the subject site. The proposed trees sholl also be flogged with yellow flogging tope on site. Such flagging shall be maintained until a final decision on the proposal is rendered. The remaining, notice, hearing and appeal procedures in LOC Chapter 55 shall not apply to tree removals considered in conjunction with o Major or Minor Development request. Subsequent tree removals that have not been reviewed through either Major or Minor Development procedures shall be reviewed as provided in this Chapter. Response: As illustrated on the preliminary plans, the site is improved with an existing home, outbuildings, driveways, retaining walls, underground utilities, etc. Trees are scattered throughout the site, but are most concentrated in the eastern portion of the property coincident with the drainageway and RP district designation. The project includes work necessary to remove the existing site improvements and provide the infrastructure necessary to support the 8 lot subdivision. This includes demolition and restoration work, grading to create the shared private access lane with appropriate transitions to the adjoining lots, and installation of underground utilities (project related). This work is clearly depicted on the Existing Conditions Plan, preliminary Demolition Plan, Preliminary Grading and �FREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) ' CITY OF LAKE OSWEGO, OREGON PAGE 45 OF 48 68 Erosion and Sediment Control Plan, and Preliminary Site, Public Improvement, and Utility Plan. Based upon the necessary improvements, a Preliminary Tree Preservation and removal Pian has been prepared by a Professional Certified Arborist. This plan identifies tree removal necessary to accommodate the required project improvements as well as includes detailed information illustrating necessary to protect and preserve the trees that will remain. As shown on the plans and the corresponding preliminary detailed tree inventory, the overwhelming majority of trees are being preserved. Trees to be removed include invasive species (English Holly and English Hawthorne) and a hazard tree (Apple) that will be removed through separate hazard/invasive species tree removal permits. Additional trees to be removed include pear trees, cherry trees, and an apple tree. All trees planned for removal will be marked with yellow flagging in the field. Prior to removal of the non- hazard/invasive species trees, a verification permit will be obtained. Tree protection fences will be in place and verified by the City through this permit prior to construction. 2. Type 11 Permit: a. A Type ll permit is required prior to any tree removal application that does not qualify in issuance as a Type 1 permit, Dead Tree Removal Permit, Hazard Tree Removal Permit, Emergency Permit, Verification Permit, or Topping Permit as described in this section. b. Type A permits shall be reviewed and approved by the City Manager pursuant to LOC 55.02.080 (Approval Criteria) and 55. 02.082 (Notice Requirements). Response: The shared access lane, drainage Swale, and utility improvements necessitate a Type 11 permit for the removal of 13 trees as shown on the preliminary plans. Additional tree removal may be needed later by separate permit for construction of new homes. Details concerning the location, species, size, and health of the trees are included on the preliminary plans. These plans have been reviewed by a Certified Arborist. 55.02.080 Criteria for Issuance of Type It Tree Cutting Permits. An applicant for a Type A tree cutting permit shall demonstrate that the fallowing criteria are satisfied. The City Manager may require an arbodst's report to substantiate the criteria for a permit. Response: A tree survey is included with the preliminary plans, and a detailed tree inventory prepared by a Certified Arborist has been included with this application. 1. The tree is proposed for removal far landscaping purposes or in order to construct development approved or allowed pursuant to the Lake Oswega Cade or other applicable development regulations. The City Manager may require the building footprint of the development to be staked to allow for accurate verification of the permit application; Response: As described above, tree removal is minimal, involving primarily "landscape" type trees, and is necessary to construct the infrastructure necessary to support the project. 2. Removal of the tree will not have a significant negative impact on erosion, sail stability, flow of surface waters, protection of adjacent trees, or existing windbreaks; and Response: Trees must be removed to accommodate improvements described above. Removal of the trees will not impact surface water flow, and proper erosion control measures will be installed. The trees to be removed are not in large groves where removal will expose other trees to potential windthrow. AKFREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 46 OF 48 69 Therefore, removal of these trees will not have a negative impact on erosion, soil stability, flow of surface water, protection of adjacent trees, or existing windbreaks. 3. Removal of the tree will not have a significant negative impact on the character, aesthetics, or property values of the neighborhood. The City may grant an exception to this criterion when alternatives to the tree removal have been considered and no reasonable alternative exists to allow the property to be used as permitted in the zone. In making this determination, the City may consider alternative site plans or placement of structures or alternate landscaping designs that would lessen the impact on trees, so long as the alternatives continue to comply with other provisions of the Lake Oswego Code. Response: Tree removal for the project is limited, is entirely located outside of the delineated RP district area, and includes a hazard tree, invasive species trees, and fruit trees among a few others. None of the trees are significantly sized evergreen trees. Removal of these trees will not have a significant impact on the character, aesthetics, or property values of the surrounding neighborhood. 4. Removal of the tree is not for the sole purpose of providing or enhancing views. Response: Tree removal is limited to the purposes described herein, not forthe purpose of enhancing views. S. The City shall require the applicant to mitigate for the removal of each tree pursuant to LOC 55.02.084. Such mitigation requirements shall be a condition of approval of the permit. Response: Mitigation is provided in the Preliminary Landscape, Screening and Tree Mitigation Planting Plan as required by LOC 55.02.084. 55.02.084 Mitigation Required 1. An applicant shall provide mitigation for any tree permitted for removal, with the exception of the following: a. Dead trees, b. Hazard trees; c. Trees that are 10 inches or less in diameter removed from developed single-family lot; d. lnvosive Tree Species, except as provided in subsection (2) of this section. 2. Mitigation for lnvosive Tree Species removal is required when: a. The removal is from a public right-of-way; b. The removal is from a Resource Conservation or Resource Protection Overlay District; or c. The tree was planted as part of o previously approved landscape or mitigation pion. 3. The mitigation requirement shall be satisfied as follows: a. Replanting on Site. The applicant shall plant, for each tree removed: i. Invasive Tree Species Removal Permit: Removal from a public right-af--way or from an approved landscape plan, either a minimum two-inch caliper deciduous tree or a six- to eight - foot -toll evergreen tree for each tree removed. Removal from a Resource Conservation or Resource Protection Overlay District, either a minimum one-holf-inch caliper deciduous tree or a minimum two -foot -tall evergreen tree. H. Other Tree Cutting Permits: Either a minimum two-inch caliper deciduous tree or a six- to eight -foot -tall evergreen tree for each tree removed. The tree shall be planted according to the specifications in the City Tree Planting and Maintenance Guidelines as approved by the City Council. Response: Mitigation is included for non-hazardous/invasive trees that are greater than 5 inches in DBH. Mitigation plantings are illustrated on the Preliminary Landscape, Screening and Tree Mitigation Planting FREEPONS VILLAGE - SUBDIVISION APPLICATION SEPTEMBER 2014 (UPDATED) CITY OF LAKE OSWEGO, OREGON PAGE 47 OF 48 70 Plan. 55.08 TREE PROTECTION 55.08.010 Applicability This article is applicable to any ministerial, minor, or major development. Response: This application is for a subdivision which is a minor development. Therefore, these standards apply to this application. 55.08.020 Tree Protection Plan Required. 1. A Tree Protection Plan approved by the City Manager shall be required prior to conducting any development activities including, but not limited to clearing, grading, excavation, or demolition work on a property or site, which requires ministerial, minor, or major development approval. 2. In order to obtain approval of a Tree Protection Plan; an applicant shall submit a plan to the City, which clearly depicts all trees to be preserved on the site. The plan must be drawn to scale and include the fallowing: Response: The preliminary plans include a Preliminary Tree Preservation and Removal Plan that provide tree protection measures required by this section of the Lake Oswego Development Code. The plan includes all of the information required above. This submittal requirement is met. 55.08.030 Tree Protection Measures Required. Response: The Preliminary Landscape, Screening and Tree Mitigation Planting Plan and arborist letter include all of the tree protection measures required by this section of the Lake Oswego Development Code. This submittal requirement is met. IV. CONCLUSION The required findings have been made and the written narrative and accompanying documentation demonstrate that the application is consistent with the applicable provisions of the City of Lake Oswego Municipal Code. The evidence in the record is substantial and supports approval of the application. Therefore, the applicant respectfully requests approval of the Freepons Village subdivision and a RP District Delineation. AFREEPONS VILLAGE - SUBDIVISION APPLICATION CITY OF LAKE OSWEGO, OREGON 48 SEPTEMBER 2014 (UPDATED) PAGE 48 OF 71 72 TUALATIN - VANCOUVER SALEM 1286 5 SW HFRNAN RD_ SUITE 100 • 7UALATIN. 0 97062 P: (503) 563-6151 F- (543)863-6152 ENGINEERING & FORESTRY June 16, 2014 Neighborhood Meeting Summary: 850 Cedar Street Lake Oswego, Oregon 97034 Eight Lot Subdivision Meeting Date: June 4th, 2014 Time: 6:00 PM Location: Hallinan Elementary School, 16800 Hawthorne Drive, Lake Oswego, Oregon 97034 The following serves as a summary of the primary subjects covered at the Neighborhood Meeting. Business cards with contact information were provided. Representatives from AKS Engineering & Forestry, Silver Oak Custom Homes, and the property owners were present. A brief presentation about the project was made, followed by questions and answers. In addition, an attendance sheet was also made available for attendees to sign. As required by the City of Lake Oswego Development Code, this written meeting summary is being provided to the recognized Neighborhood Associations and County Citizen Participation Organizations who were notified of the meeting. Topics of discussion: • History of the property ■ Density (project is under allowable maximum density) ■ Parking (on and off street) ■ Additional traffic, waste management access ■ Construction activities (parking, other off-site projects) ■ Property values and square footage of future homes • Lot sizes, R-7.5 zoning • Future market demands * Stormwater management • Utility infrastructure ■ Location of the open space • Park boundary to the south • Tree removal and/or protection ■ Anticipated start date of this project ■ City process for the PUD subdivision of existing lots of record (it should be noted that the City Development Review Commission is the decision maker for the PUD subdivision application) • Home building and other activities in the area not associated with this project Sincerely, AKS ENGINEERING & FORESTRY, CLC Chris Goodell, AICP, LEED AP Associate =EXHIBIT -246 73 74 Lake Oswego Fire Department Case File/Permit No. 300 B AVE - P.O. Box 369 LU 14-0046 Lake Oswego, OR 97034 503-635-0275 Date: October 6, 2014 To: Jessica Numanoglu, Senior Planner From: Gert ZoutendijklFire Marshal Email: gzoutendijk@6oswego.or.us Phone: 503-699-7454 Fire Department - Plan review Comments I have received the information for the project summarized below and completed a review of the submittal on 10/06/2014 - A summary of the review has been provided. Please feel free to contact me directly if you have any questions, comments or concerns regarding this information. Case FilelPermit No.: LU 14-0046 Project Location: 850 Cedar Scope of Project: Resubmittal for Residential Subdivision FIRE DEPARTMENT ACCESS 503.1.1 Access within 150' of Buildings Approved fire apparatus access roads shall be provided for every facility, building or portion of a building hereafter constructed or moved into or within the jurisdiction. The fire apparatus access road shall comply with the requirements of this section and shall extend to within 150 feet (45 720 mm) of all portions of the facility and all portions of the exterior walls of the first story of the building as measured by an approved route around the exterior of the building or facility. Exception: The fire code official is authorized to modify Sections 503.1 and 503.2 where any of the following applies: 1. The building is equipped throughout with an approved automatic sprinkler system installed in accordance with Section 903.3.1.1, 903.3.1.2 or 903.3.1.3. 2. Fire apparatus access roads cannot be installed because of location on property, topography, waterways, nonnegotiable grades or other similar conditions, and an approved alternative means of fire protection is provided. 3. There are not more than two Group R-3 or Group U occupancies. 543.2.5 Dead Ends Dead-end fire apparatus access roads in excess of 150 feet in length shall be provided with an approved area for turning around fire apparatus. The modified turn -around is approved but wilt have to be marked "No Parking''. Lots 2-7 will need to be provided with fire sprinklers due to the modified turn -around which does not meet the fire code standards. ❑103.2 Grade Fire apparatus access roads shall not exceed 10 percent in grade. When fire sprinklers are installed, a maximum grade of 15% may be allowed. The access where it is indicated the fire engine could park far lots 1 and 8 is over 10%I Fire sprinklers EXHIBIT F-3 LU 14-0046 75 Lake Oswego Fire Department - Plan Review Comments Case FilelPermit No. LU 14-0046 would be approved as an alternate method or the grade wili have to be less than 10% 503.3 Fire Lane Marking Where required by the fire code official, approved signs or other approved notices or markings that include the words NO PARKING FIRE LANE shall be provided for fire apparatus access roads to identify such roads or prohibit the obstruction thereof. The means by which fire lanes are designated shall be maintained in a clean and legible condition at all times and be replaced or repaired when necessary to provide adequate visibility. Parking will only be allowed on one side of the road and the other side will have to be posted "No Parking" anywhere the access is at least 26' or posted on both sides when less than 26'. the turn -around will also have to be posted, D103.6 Parking Signs and Requirements D103.6 Signs. Where required by the fire code official, fire apparatus access roads shall be marked with permanent NO PARKING - FIRE LANE signs complying with Figure D103.6. Signs shall have a minimum dimension of 12 inches (305 mm) wide by 18 inches (457 mm) high and have red letters on a white reflective background. Signs shall be posted on one or both sides of the fire apparatus road as required by Section D103.6.1 or D103.6.2, D103.6.1 Roads 20 to 26 feet in width. Fire apparatus access roads 20 to 26 feet wide (5095 to 7925 mm) shall be posted on both sides as a fire lane. D103.6.2 Roads more than 26 feet in width. Fire apparatus access roads more than 26 feet wide (7925 mm) to 32 feet wide (9754 mm) shall be posted on one side of the road as a fire lane. WATER FLOW FOR FIRE PROTECTION VVS-0003 Hydrant Location Approved Hydrant location with distance and size of the structure is approved. WS -0007 Fire Flow Approved Fire flow for fire protection is adequate. GENERAL COMMENTS G-0002 Alternate Method For any deficiencies in access or water supply applicant could propose an alternate method in accordance with the provisions of CRS 455.610(5) in the form of fire sprinklers as approved by the Fire Marshal. Due to the grade and modifeid turn -around, all lots will have to be proposed to have an alternate method like fire sprinklers installed. Page 2 of 2 76 6 iopl�Go Real -World Geotechnical Solutions Investigation - Design • Construction Support July 25, 2014 Project No. 14-3393 Roger Edwards Silver Oak Custom Homes 14102 Goodall Road Oswego, OR 97034 CC: Jon Morse - AKS Engineering & Forestry, 'onm aks-en .com SUBJECT: GEOTECHNICAL REPORT FREEPONS VILLAGE 850 CEDAR STREET LAKE OSWEGO, OREGON This report presents the results of a geotechnical engineering study conducted by GeoPacific Engineering, Inc. (GeoPacific) for the above -referenced project. The purpose of our investigation was to evaluate subsurface conditions at the site and to provide geotechnical recommendations for site development. This geotechnical study was performed in accordance with GeoPacific Proposal No. P-4822, dated April 25, 2014, and your subsequent authorization of our proposal and General Conditions for Geotechnical Services. SITE DESCRIPTION AND PROPOSED DEVELOPMENT The subject site is located at the western terminus of Cedar Street in Lake Oswego, Clackamas County, Oregon (Figure 1). The site is approximately 2.2 acres in size and topography is Predominantly flat to gently sloping to the north at grades of approximately 5 to 25 percent. Steeper slopes (up to approximately 65 percent grade) are present along the northern property line and along a shallow drainage in the northeastern portion of the site. One home and outbuilding are located on the property and vegetation consists primarily of short grasses, landscaping, and sparse trees. It is our understanding that the proposed development includes 8 lots for single family homes, new street, and associated underground utilities. A grading plan has not been provided for our review; however, we anticipate maximum cuts and fills will be on the order of 5 feet or less. REGIONAL AND LOCAL GEOLOGIC SETTING The subject site lies within the Willamette Valley/Puget Sound lowland, a broad structural depression situated between the Coast Range on the west and the Cascade Range on the east. A series of discontinuous faults subdivide the Willamette Valley into a mosaic of fault -bounded, 14835 SW 72"" Avenue Portland, Oregon 97224 EXHIBIT F-4 LU 14-0046 W 77 Freer)ons Villaoe Subdivision Project No. 14-3393 structural blocks (Yeats et al., 1996). Uplifted structural blocks form bedrock highlands, while down -warped structural blocks form sedimentary basins. The site is underlain by the late Quaternary aged (last 1.6 million years) Willamette Formation. a catastrophic flood deposit associated with repeated glacial outburst flooding of the Willamette Valley (Yeats et al., 1996). The last of these outburst floods occurred about 10,000 years ago These deposits typically consist of horizontally layered, micaceous, silt to coarse sand forming poorly-defined to distinct beds less than 3 feet thick. (Madin, 1990). Underlying the Willamette Formation is a Pliocene to Pleistocene -aged (10,700 to 5.3 million years ago) conglomerate and sandstone that was likely deposited by Cascadian streams or an ancestral Clackamas River (Beeson et al., 1989). Madin (19 90) maps this conglomerate as the Tertiary -aged (2-65 million years ago) Troutdale Formation. REGIONAL SEISMIC SETTING Al least three major fault zones capable of generating damaging earthquakes are thought to exist in the vicinity of the subject site. These include the Portland Hills Fault zone, the Gates Creek - Newberg -Mt. Angel Structural Zane, and the Cascadia Subduction Zone. Portland Hills Fault Zone The Portland Hills Fault Zone is a series of NW -trending faults that include the central Portland Hills Fault, the western Oatfield Fault, and the eastern East Bank Fault These faults occur in a northwest -trending zone that varies in width between 3.5 and 5.0 miles. The combined three faults vertically displace the Columbia River Basalt by 1,130 feet and appear to control thickness changes in late Pleistocene (approx. 780,000 years) sediment (Madin, 1990). The Portland Hills Fault occurs along the Willamette River at the base of the Portland Hills, and is about 3 miles northeast of the site. The Oatfieid Fault occurs along the western side of the Portland Hills, and is about 1 mile northeast of the site. The Darfield Faun is considered to be potentially seismogenic (Wong, et al., 2000). Madin and Mabey (1996) indicate the Portland Hills Fault Zone has experienced Late Quaternary (last 780.000 years) fault movement; however, movement has not been detected in the last 20,000 years. The accuracy of the fault mapping is stated to be within 500 meters (Wong, et al., 2000). No historical seismicity is correlated with the mapped portion of the Portland Hills Fault Zone, but in 1991 a M3.5 earthquake occurred on a NW -trending shear plane located 1.3 miles east of the fault (Yelin, 1992). Although there is no definitive evidence of recent activity, the Portland Hills Fault Zone is assumed to be potentially active (Geomatrix Consultants, 1995). Gales Creek -Newberg -Mt. Angel Structural Zone The Gales Creek -Newberg -Mt, Angel Structural Zone is a 50 -mile -long zone of discontinuous, NW -trending faults that lies about 18.5 miles southwest of the subject site. These faults are recognized in the subsurface by vertical separation of the Columbia River Basalt and offset seismic reflectors in the overlying basin sediment (Yeats et al., 1996; Werner et al., 1992). A geo€ogic reconnaissance and photogeologic analysis study conducted for the Scoggins Dam site in the Tualatin Basin revealed no evidence of deformed geomorphic surfaces along the structural zone (Unruh et al., 1994). No seismicity has been recorded on the Gales Creek Fault or Newberg Fault (the fault closest to the subject site); however, these faults are considered to be potentially active because they may connect with the seismicaiiy active Mount Angei Fault and the rupture 3393-Freepons Village GR 78 GEOPACIFic ENGINEERING, INC. Freepons Village Subdivision Project No. 14-3393 plane of the 1993 M5.6 Scotts Mills earthquake (Werner et al. 1992; Geomatrix Consultants, 1995). Cascadia Subduction Zone The Cascadia Subduction Zone is a 680 -mile -long zone of active tectonic convergence where oceanic crust of the Juan de Fuca Plate is subducting beneath the North American continent at a rate of 4 cm per year (Gold€finger et al,, 1996). A growing body of geologic evidence suggests that prehistoric subduction zone earthquakes have occurred (Atwater, 1992; Carver, 1992; Peterson et al., 1993; Geomatrix Consultants, 1995). This evidence includes: (1) buried tidal marshes recording episodic, sudden subsidence along the coast of northern California, Oregon, and Washington, (2) burial of subsided tidal marshes by tsunami wave deposits, (3) palecliquefaction features, and (4) geodetic uplift patterns on the Oregon coast. Radiocarbon dates on buried tidal marshes indicate a recurrence interval for major subduction zone earthquakes of 250 to 650 years with the last event occurring 300 years ago (Atwater, 1992; Carver, 1992; Peterson et al., 1993; Geomatrix Consultants, 1995). The inferred seismogenic portion of the plate interface lies roughly along the Oregon coast at depths of between 20 and 40 miles. SUBSURFACE CONDITIONS Our site-specific exploration for this report was conducted on May 14, 2014. A total of 2 exploratory test pits were excavated with a backhoe to depths of 5 to 8 feet at the approximate locations indicated on Figure 2. Three hand auger borings were performed to a depth of 3.5 to 10 feet (see Figure 2). ft should be noted that exploration locations were located in the field by pacing or taping distances from apparent property corners and other site features shown on the plans provided. As such, the locations of the explorations should be considered approximate. A GeoPacific geologist continuously monitored the field exploration program and logged the test pits and nand auger borings. Soils observed in the explorations were classified in general accordance with the Unified Soil Classification System. During exploration, our geologist also noted geotechnical conditions such as soil consistency, moisture and groundwater conditions. Logs of test pits and hand auger borings are attached to this report. The following report sections are based on the exploration program and summarize subsurface conditions encountered at the site. Undocumented Fill: Undocumented fill was encountered in hand auger boring HA -3 to a depth of 7 feet. The fill generally consisted of approximately 1 foot of medium dense to dense, silty GRAVEL (GM) underlain by soft to stiff clayey SILT (ML) to silty CLAY (CL) to a depth of 7 feet. Other areas of fill may be present outside our explorations -- especially in the vicinity of the existing structures and driveway. Buried Topsoils Horizon: The fill in hand auger boring HA -3 was underlain by a buried topsoil horizon. The buried topsoil horizon consisted of soft, gray, moderately organic SILT (OL -ML) that was approximately 112 foot thick and extended to a depth of 7.5 Feet, Topsoil Horizon: Directly Underlying the ground surface in test pits TP -3 and TP -4 and hand auger borings HA -1 and HA -2 was a topsoil horizon consisting of browns, low to moderately organic SILT (OL -ML). The topsoil horizon was loose, contained fine roots, and extended to a depth of about 6 to 10 inches. 3393-Freepons Village GR GEOPACIFIC ENGINEERING, INC. 79 Freepons Village Subdivision Project No. 14-3393 Willamette Formation: Underlying the topsoil horizon in test pit TP -3 was clayey SILT (ML) belonging to the Willamette Formation. The light brown silt was generally characterized by a stiff to very stiff consistency with strong orange and gray mottling. The loess extended to a depth of 2.5 feet in test pit TP -3 - Residual Soil: Underlying the topsoil horizon in test pit TP -3 and hand auger borings HA -3 and HA -2, the Willamette Formation in test pit TP -3, and the buried topsoil horizon in hand auger boring HA -3 was residual soil derived from in place decomposition of the underlying unnamed conglomerate. The light brown silty CLAY (CL) to clayey SILT (ML) was generally characterized by a stiff to very stiff, consistency with strong orange and gray mottling. The residual soil material extended beyond the maximum depth of exploration in test pits and hand auger borings (10 feet). Soil Moisture and Groundwater On May 14, 2014, groundwater seepage was encountered in test pit TP -4 at depths of 3 and 5 feet below the ground surface. Discharge was visually estimated at less than '/2 gallon per minute. Experience has shown that temporary storm related perched groundwater within the near surface soils often occur over fine-grained native deposits such as those beneath the site during the wet season and particularly in mottled soils such as were identified in the test pits, it is anticipated that groundwater conditions will vary depending on the season, local subsurface conditions, changes in site utilization, and other factors. INFILTRATION TESTING The pushed pipe method of infiltration testing was performed in test pits TP -3 and TP -4. The open -hole method was used in hand auger borings HA -1 and HA -2. The soil in the test pits and hand auger borings were pre -saturated for a period of 2 hours prior to conducting the testing. The water level was measured to the nearest tenth of an inch every twenty to thirty minutes with reference to the ground surface. Table 1 presents the results of our falling head infiltration tests. Table 9. Summary of Infiltration Test Results Exploration Depth Sail Type Infiltration Hydraulic Head Range Designation (feet) Rate(inthr) inches TP -3 3 Clayey SILT (ML) or silty � 9 12-17 5 2.6 12-15 CLAY (CL) trace sand TP -4 g Clayey SILT (ML) or silty g ,I 23-24 CLAY CL HA -1 5 Clayey SILT (ML) or silty 0.5 9-11 CLAY CL HA -2 3.5 Clayey SILT (ML) or silty 1.9 20-25 CLAY (CL 3393-Freepons V10ge GR 80 GEOPACIFic ENGINEERING, INC. Freepons Village Subdivision Project No, 14-3393 SLOPE STABILITY For the purpose of evaluating slope stability, we: (1) reviewed published geologic mapping and LIOAR imagery, (2) performed field reconnaissance, and (3) explored subsurface conditions in two exploratory test pits with a small trackhoe and performed three hand auger borings. Explorations indicate the site is underlain by medium stiff to very stiff residual soil that is considered highly resistant to slope instability in areas of gently sloping topography and moderately resistant in areas of moderately to steeply sloping topography. The DOGAMI online landslide database (DOGAMI, 2014) and published geologic mapping Indicates no mapped landslides area present at the site or adjacent properties (Beeson et al., 1989; Madin, 1990). A concealed fault is mapped by Beeson et al (1989) that bisects the site as indicated on Figure 1A. Our review of Iidar irnagery (DOGAM1, 2014) indicates arcuate topography along the northern property line that may be a possible old landslide scarp, related to the concealed fault, or an erosional feature tram the Missoula Floods (see Figures 1 A and 18), Relative dynamic slope instability mapping by Mabey et al. (199 5) indicates the majority of the site characterized as "having slope instability only in unusual localized conditions" with the northern slope characterized as having a low slope instability hazard. The site is characterized as having a moderate relative earthquake hazard (Zone B) where Zone A is the greatest hazard and Zone D is the least hazard (Mabey et al., 1995). The majority of the subject site is gently to moderately sloping to the north inclining at grades of 5 to 20 percent. Grades steepen to the north, north of the existing driveway, where grades average 55 to 65 percent. The northern slope has been oversteepened by the placement of fill at the top of the slope (7 feet as encountered in hand auger boring HA -3) and at the toe with the placement of a gabion wall (Figure 3). An incised drainage with steeply sloping grades is present in the eastern portion of the property. This area will remain undeveloped due to a resource protection buffer. To decrease the slope instability hazard, we recommend the fill at the top of the slope be removed to native, stiff soils and that storm related runoff is collected and disposed of off-site (see Figure 3). CONCLUSIONS AND RECOMMENDATIONS Our investigation indicates that the proposed development is geotechnicaily feasible, provided that the recommendations of this report are incorporated into the design and sufficient geotechnical monitoring is incorporated into the construction phases of the project. In our opinion, the greatest geotechnical issues for project completion are the potential for perched groundwater conditions and the steep slope at the north end of the site. The northern slope has been oversteepened by the placement of fill at the top of the slope (7 feet as encountered in hand auger boring HA -3) and at the toe with the placement of a gabion wall. To decrease the slope instability hazard, we recommend the fill at the top of the slope be removed to native, stiff soils and that storm related runoff is collected and disposed of off-site (see Figure 3). We do not recommend the use of open detention or stormwater infiltration facilities due to the potential for adverse impacts to slope stability. Site Preparation Areas of proposed buildings, new streets, and areas to receive engineered fill should be cleared of vegetation and any organic and inorganic debris. If encountered, existing burled structures should be demolished and any cavities structurally backfilled with engineered fill as 3393-Freepons Village GR GEOPACIFIC ENGINEERING, INC. 81 Freepons Village Subdivision Project No. 14-3393 recommended in this report. Inorganic debris and organic materials from clearing should be removed from the site. Existing fill, buried topsoil horizons, and any organic -rich topsoil should then be stripped from construction areas of the site or where engineered fill is to be placed. Fill was encountered in hand auger boring HA -3 to a depth of 7 feet. Topography indicates fill has been placed along the top of the northern slope. This fill should be removed. The estimated depth range necessary for removal of topsoil is approximately 6 to 9 inches. The final depth of soil removal will be determined on the basis of a site inspection after the stripping/ excavation has been perfori-ned. Stripped topsoil should preferably be removed from the site. Any remaining topsoil should be stockpiled only in designated areas and stripping operations should be observed and documented by the geotechnical engineer or his representative. Any remaining undocumented fills and subsurface structures Mile drains. basements, driveway and landscaping fill, old utility lines, septic leach fields, etc.) should be removed and the excavations backfilled with engineered fill. Once stripping of a particular area is approved, the area must be ripped or tilled to a depth of 12 inches, moisture conditioned, root -picked, and compacted in-place prior to the placement of engineered fill or crushed aggregate base for pavement. Exposed subgrade soils should be evaluated by the geotechnical engineer. For large areas, this evaluation is normally performed by proof -rolling the exposed subgrade with a fully loaded scraper or dump truck. For smaller areas where access is restricted, the subgrade should be evaluated by probing the soil with a steel probe. Soft/ioose soils identified during subgrade preparation should be compacted to a firm and unyielding condition, over -excavated and replaced with engineered fill (as described below), or stabilized with rock prior to placement of engineered fill. The depth of overexcavation, if required, should be evaluated by the geotechnical engineer at the time of Construction. Engineered Fill All grading for the proposed development should be performed as engineered grading in accordance with the applicable building code at time of construction with the exceptions and additions noted herein. Proper test frequency and earthwork documentation usually requires daity observation and testing during stripping, rough grading, and placement of engineered fill. Imported fill material must be approved by the geotechnical engineer prior to being imported to the site. Oversize material greater than 6 inches in size should not be used within 3 feet of foundation footings, and material greater than 12 inches in diameter should not be used in engineered fill. Engineered fill should be compacted in horizontal lifts not exceeding 8 inches using standard compaction equipment. We recommend that engineered fill be compacted to at least 90% of the maximum dry density determined by ASTM D1557 (Modified Proctor) or equivalent. Field density testing should conform to ASTM D2922 and D3617, or D1556. All engineered fill should be observed and tested by the project geotechnical engineer or his representative. Typically, one density test is performed for at least every 2 vertical feet of fill placed or every 500 yd', whichever requires more testing. Because testing is performed on an on-call basis, we recommend that the earthwork contractor be held contractually responsible for test scheduling and frequency. 3393-Freepons Village GR 6 GEOPACIFlc ENGINEERING, INC. 82 Freepons Village Subdivision Project iso. 14-3393 Site earthwork will be impacted by soil moisture and shallow groundwater conditions. Earthwork in wet weather would likely require extensive use of cement or lime treatment, or other special measures, at considerable additional cost compared to earthwork performed under dry -weather conditions. Excavati ng Conditions and Uti I ity Frenches We anticipate that on-site soils can be excavated to a depth of 8 feet using conventional heavy equipment such as scrapers and trackhoes. All temporary cuts in excess of 4 feet in height should be sloped in accordance with U.S. Occupational Safety and Heath Administration (OSHA) regulations (29 CFR Part 1926), or be shored. The existing native soils classify as Type B Soil and temporary excavation side slope inclinations as steep as 1 H:1 V may be assumed for planning purposes- This cut slope inclination is applicable to excavations above the water table only. Maintenance of safe working conditions. including temporary excavation stability, is the responsibility of the contractor. Actual slope inclinations at the time of construction should be determined based on safety requirements and actual salt and groundwater conditions. Saturated soils and groundwater may be encountered in utility trenches, particularly during the wet season. We anticipate that dewatering systems consisting of ditches, sumps and pumps would be adequate for control of perched groundwater. Regardless of the dewatering system used, it should be installed and operated such that in-place soils are prevented from being removed along with the groundwater. Vibrations created by traffic and construction equipment may cause some caving and raveling of excavation walls. In such an event, lateral support for the excavation walls should be provided by the contractor to prevent loss of ground support and possible distress to existing or previously constructed structural improvements. PVC pipe should he installed in accordance with the procedures specified in ASTM X2321, We recommend that trench backfill be compacted to at feast 90% of the maximum dry density obtainad by Modified Proctor ASTM D1557 or equivalent. Initial backfill lift thickness far a 314"-9 crushed aggregate base may need to be as great as 4 feet to reduce the risk of flattening underlying flexible pipe. Subsequent lift thickness should not exceed 1 foot. If imported granular fill material is used, then the lifts for large vibrating plate -compaction equipment (e.g. hoe compactor attachments) may be up to 2 feet, provided that proper compaction is being achieved and each lift is tested. Use of large vibrating compaction equipment should be carefully monitored near existing structures and improvements due to the potential for vibration - induced damage. Adequate density testing should be performed during construction to verify that the recommended relative compaction is achieved. Typically, one density test is taken for every 4 vertical feet of backfill on each 200 -lineal -foot section of trench. Erosion Control Considerations During our field exploration program, we did not observe soil types that would be considered highly susceptible to erosion. In our opinion, the primary concern regarding erosion potential will occur during construction, in areas that have been stripped of vegetation. Erosion at the site during construction can be minimized by Implementing the project erosion control plan, which 3393-Freepons Village GR GeOPACIFIc ENGINEERING, INC. 83 Freepons Village Subdivision Project No. 14-3393 should include judicious use of straw bales and silt fences. If used, these erosion control devices should be in place and remain in place throughout site preparation and construction. Erosion and sedimentation of exposed soils can also be minimized by quickly re -vegetating exposed areas of soil, and by staging construction such that large areas of the project site are not denuded and exposed at the same time. Areas of exposed soil requiring immediate and/or temporary protection against exposure should be covered with either mulch or erosion control netting/blankets. Areas of exposed soil requiring permanent stabilization should be seeded with an approved grass seed mixture, or hydroseeded with an approved seed -mulch -fertilizer mixture. Wet Weather Earthwork Soils underlying the site are likely to be moisture sensitive and may be difficult to handle or traverse with construction equipment during periods of wet weather. Earthwork is typically most economical when performed under dry weather conditions- Earthwork performed during the wet -weather season will probably require expensive measures such as cement treatment or imported granular material to compact fill to the recommended engineering specifications- If earthwork is to be performed or fiiI is to be placed in wet weather or under wet conditions when soil moisture content is difficult to control. the following recommendations should be incorporated into the contract specifications_ Earthwork should be performed in small areas to minimize exposure to wet weather_ Excavation or the removal of unsuitable soils should be followed promptly by the placement and compaction of clean engineered fill. The size and type of construction equipment used may have to be limited to prevent soil disturbance. Under some circumstances, it may be necessary to excavate soils with a backhoe to minimize subgrade disturbance caused by equipment traffic; The ground surface within the construction area should be graded to promote run-off of surface water and to prevent the ponding of water; Material used as engineered fill should consist of clean, granular soil containing less than 5 percent fines. The fines should be non -plastic. Alternatively, cement treatment of on-site soils may be performed to facilitate wet weather placement; .- The ground surface within the construction area should be sealed by a smooth drum vibratory roller, or equivalent, and under no circumstances should be left uncompacted and exposed to moisture. Soils which become too wet for compaction should be removed and replaced with clean granular materials; Excavation and placement of fill should be observed by the geotechnical engineer to verify that all unsuitable materials are removed and suitable compaction and site drainage is achieved; and Y Bales of straw and/or geotextile silt fences should be strategically located to control erosion. If cement or lime treatment is used to facilitate wet weather construction, GeoPacific should be contacted to provide additional recommendations and field monitoring. 3393-Freepons Village GFS 84 GEOPACIFIc ENGINEERING, INC. Freepons Village Subdivision Project No. 14-3393 Anticipated Foundations The proposed residential structures may be supported on shallow foundations bearing on competent undisturbed, native soils andlor engineered fill, appropriately designed and constructed as recommended in this report. Foundation design, construction, and setback requirements should conform to the applicable building code at the time of construction. For maximization of bearing strength and protection against frost heave, spread footings should be embedded at a minimum depth of 18 inches below exterior grade. The recommended minimum widths for continuous footings supporting wood -framed wails without masonry are 12 inches for single -story, 15 inches for two-story, and 18 inches for three-story structures. Mtn imum foundation reinforcement should consist of a No. 4 bar at the top of stem walls, and a No, 4 bar at the bottom of footings. The anticipated allowable soil bearing pressure is 1,500 lbs/ft` for footings bearing on competent, native soil and/or engineered fill. A maximum chimney and column load of 30 kips is recommended for the site. The recommended maximum allowable bearing pressure may be increased by 113 for short -terra transient conditions such as wind and seismic loading. For heavier loads, the geotechnical engineer should be consulted. The coefficient of friction between on-site soil and poured -in-place concrete may be taken as 0.45, which includes no factor of safety. The maximum anticipated total and differential footing movements (generally from soil expansion and/or settlement) are 1 inch and 3/4 inch over a span of 20 feet, respectively. We anticipate that the majority of the estimated settlement will occur during construction, as loads are applied. Excavations near structural footings should not extend within a 1H:'IV plane projected downward from the bottom edge of footings. Footing excavations should penetrate through topsoil and any loose soil to competent subgrade that is suitable for bearing support. All footing excavations should be trimmed neat, and all loose or softened soil should be removed from the excavation bottom prior to placing reinforcing steel bars. Due to the moisture sensitivity of on-site native soils, foundations constructed during the wet weather season may require overexcavation of footings and backfill with compacted, crushed aggregate. Our recommendations are for house construction incorporating raised wood floors and conventional spread footing foundations. If living space of the structures will incorporate basements, a geotechnical engineer should be consulted to make additional recommendations for retaining walls, water -proofing, underslab drainage and wall subdrains. After site development, a Final Soil Engineers Report should either confirm or modify the above recommendations. Drainage The outside edge of uphill perimeter footings may be provided with a drainage system consisting of 3 -inch diameter, slotted, plastic pipe embedded in a minimum of 1 ft' per lineal toot of clean, free -draining gravel or 314" — 0 rock. Water collected from the footing drains should be directed into the local storm drain system or other suitable outlet. A minimum 0.5 percent fall should be maintained throughout the drain and non -perforated pipe outlet. Down spouts and roof drains should not be connected to the foundation drains in order to reduce the potential for clogging. The footing drains should include clean -outs to allow periodic maintenance and inspection. Grades around the proposed structure should be sloped such that surface water drains away frorn the building. An adequate grade to a low point outlet drain in the crawlspace is required by code. 3393-Freepons Village GR GEoPACIFIc ENGINEERING, INC. 85 Freepons Village Subdivision Project No. 14-3393 Seismic design Structures should be designed to resist earthquake loading in accordance with the methodology described in the 2006 International Residential Code {IRC} for One- and Two -Family Dwellings, with applicable Oregon Structural Specialty Code (OSSC) revisions. We recommend Site Class D be used for design per the OSSC, Table 1613.5.2. Design values determined for the site using the USGS. (United States Geological Survey) Earthquake Ground Motion Parameters utility are summarized in Table 2 - presented on the following page. Table 2 - Recommended Earthquake Ground Motion Parameters (2006 IRC) Parameter Value 45.406, -122.674 Location (Lat, Long), degrees Mapped Spectral Acceleration Values MICE). Short Period, Sg 0.95 1.0 Sec Period, S, O3 34 Soil Factors for Site Class D- F, 1.12 Fv 1.73 Residential Site Value = 213 x Fa x Ss 0.71 Residential Seismic Design Category D, Soil liquefaction is a phenomenon wherein saturated soil deposits temporarily lose strength and behave as a liquid in response to earthquake shaking. Soil liquefaction is generally limited to loose, granular soils located below the water table. Following development, on-site soils will consist predominantly of engineered fill, native fine-grained soils, or basalt bedrock, which are not considered susceptible to liquefaction. Therefore; it is our opinion that special design or construction measures are not required to mitigate the effects of liquefaction. 3393-Freepons Village GR 1 [) GEOPACIF}c ENGINEERING, INC. 86 Freepons Village Subdivision Project No. 14-3393 UNCERTAINTIES AND LIMITATIONS We have prepared this report for the owner and their consultants for use in design of this project only. This report should be provided in its entirety to prospective contractors for bidding and estimating purposes; however, the conclusions and interpretations presented in this report should not be construed as a warranty of the subsurface conditions. Experience has shown that soil and groundwater conditions can vary significantly over small distances. Inconsistent conditions can occur between explorations that may not be detected by a geotechnical study. If, during future site operations, subsurface conditions are encountered which vary appreciably from those described herein, GeoPacific should be notified for review of the recommendations of this report, and revision of such if necessary. Sufficient geotechnical monitoring, testing and consultation should be provided during construction to confirm that the conditions encountered are consistent with those indicated by explorations. The checklist attached to this report outlines recommended geotechnical observations and testing for the project. Recommendations for design changes will be provided should conditions revealed during construction differ from those anticipated, and to verify that the geotechnical aspects of construction comply with the contract plans and specifications. Within the limitations of scope, schedule and budget, GeoPacific attempted to execute these services in accordance with generally accepted professional principles and practices in the fields of geotechnical engineering and engineering geology at the time the report was prepared. No warranty, expressed or implied, is made. The scope of our work did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous or toxic substances in the soil, surface water, or groundwater at this site. We appreciate this opportunity to be of service. Sincerely, GEOPACIFIC ENGINEERING, INC. Beth K. Rapp, R.G. Senior Geologist �REa PROF�� Q5GIN�F 147 OREGON "y 3 fir MMES D. IMS EXPIRES: D6130J20 /5 James D. Imbrie, P.E., G.E. Principal Geotechnical Engineer Attachments. References Figure 1A — Vicinity Map Figure 18 — LIDAR Map Figure 2 — Site and Exploration Plan Test Pit Logs (TP -3 and TP -4) Hand Auger Logs (HA -1 through HA -3) 3393-Freepons Village GR 11 GEOPACIFIc ENGINEERING, INC. 87 Freepons Village Subdiwsion Project No, 14-3393 REFERENCES Atwater, B.F., 1992, Geologic evidence for earthquakes during the past 2,040 years along the Copalis River. southern coastal Washington: Journal of Geophysical Research, v. 97, p_ 1901-1919. Beeson, M.H., Toian, T.L., and Madin. I.P., 1989, Geologic map of the Lake Oswego Quadrangle, Clackamas, Multnomah, and Washington Counties, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS -59, scale 1:24,000. Carver, G.A., 1992, Late Cenozoic tectonics of coastal northern California: American Association of Petroleum Geologists-SEPM Field Trip Guidebook, May, 1992. Geomatrix Consultants, 1995, Seismic Design Mapping, State of Oregon: unpublished report prepared for Oregon Department of Transportation, Personal Services Contract 11688, January 1995, Goidfinger, C., Kulm, L.D., Yeats, R.S., Appelgate, B, Mackay, M.E., and Cochrane, G.R., 1996, Active strike - slip faulting and folding of the Cascadia Subduction-Zone plate boundary and foreare in central and northern Oregon: in Assessing earthquake hazards and reducing risk in the Pacific Northwest, v. 1: U.S. Geological Survey Professional Paper 1560, P. 223-256 Madin, I.P., 1990, Earthquake hazard geology maps of the Portland metropolitan area, Oregon; Oregon Department of Geology and Mineral Industries Open -File Report 0-90-2, scale 1:24,000, 22 p. Mabey, M.A., Madin, I.P., and Meier. D. B.. 1995, Relative earthquake map of the Lake Oswego Quadrangle, Clackamas and Multnomah Counties, Oregon: Oregon Department of Geology and Mineral Industries, GMS -91, 6 pages, scale 1:24,000. Oregon Department of Geology and Mineral Industries. 2014, Statewide Landslide Information Database for Oregon (SLIDO): htto:l/www.oregqngeolo-gy.orgislido/index.htmI Peterson, C.Q., Dadoenzo, M.E., Burns, S.F., and Burris, W.K., 1993, Field trip guide to Cascadia paleoseismic evidence along the northern California coast: evidence of subduction zone seismicity in the central Cascadia margin: Oregon Geology, v. 55, p. 99-144. Unruh, J. R-, Wong, I. G., Bott, J. D., Silva, W.J., and Lettis, W, R., 1994, Seismotectanic evaluation: Scoggins Dam, Tualatin Project, Northwest Oregon: unpublished report by William Lettis and Associates and Woodward Clyde Federal Services, Oakland, CA, for U. S. Bureau of Reclamation, Denver CO (in Geomatrix Consultants, 1995), Werner, K.S., Nabelek, J., Yeats, R.S., Malone, S., 1992, The Mount Angel fault: implications of seismic - reflection data and the Woodburn, Oregon, earthquake sequence of August, 1990. Oregon Geology, v. 54, p. 112-117. Wong, I. Silva, W., Bott, J., Wright, D_, Thomas, P., Gregor, N., Li., S., Mabey, M., Sojourner, A., and Wang, Y., 2000, Earthquake Scenario and Probabiiistic Ground Shaking Maps for the Portland. Oregon, Metropolitan Area; State of Oregon Department of Geology and Mineral Industries; Interpretative Map Series tMS-15. Yeats, R.S., Graven, E.P_, Werner, K.S., Goldfinger, C., and Popowski, T , 1995, Tectonics of the Willamette Valley, Oregon: in Assessing earthquake hazards and reducing risk in the Pacific Northwest, v. 1: U.S. Geological Survey Professional Paper 1560, P. 183-222, 5 plates, scale 1:100,000. Yelin, T.S., 1992, An earthquake swarm in the north Portland Hills (Oregon); More speculations on the seismotectonics of the Portland Basin: Geological Society of America, Programs with Abstracts, v. 24, no 5, p_ 92. 3393-Freepons Village GR 12 GEOPACIFIC ENGINEERING, INC. 88 fZp� 14835 5W 72nd Avenue Gea Portland, Oregon 97224 VICINITY MAP Tel: (503) 598-8445 Fax: (503) 941-9281 t.f.u��''F'.F.1-.i'Ii k[I'; l ` t � � � +4 ;t l i��'.rrr .r.s .;•� A• w ~ -. ' moi' •io �- It!f.• �� N hf�"'I J'I N �_� � _.�' r r 1 'F...�• • .`:t _ .. .y,�'y,'',l•rr' Leff � I � � � ! . l ; i .hi'.�•• 7 ail;r e 6K�'.aii�';.f•�,'l�... ;a.�� ,1 /// 1.+ �•yh r ����'f •�j�• i!w .f a'� I��bl ��r�.�•. .i' ?i. }y; f�'-. .'� i 4� i� " 1,Wmtr,�sr +f .ti I� IIS. tVY. --� - `�.-�'�"' �` i�titlil ,_ t: L i i .' Vk�fJ itliM.• ' �•+�'��. '� Tqsb 't , L)rif�,r rg9t7 ' 'irk-' •'LIM ^'�`.,I •��� 'IIS �lilf:k �'r�f�! ! t ;IU..t i' TgWW r•nrl Vit. ►rnrrlt�. k.41 16 fes_ .f•r �„ ).. .�. .Y ;Ms SUBJECT SITETig 4�r t h.. •� . 11+1•.11 i',u r' Mu I .J � .4i� � µ •,!j `'�.. ,'�.•�. T[g , y.. .Il: �I'frR�d I'II!'Yt+ f rr ]� ■ •littitpw,_.� ro.m.I t'p I ` •vY (� � 1[ • ai l:ii Yl ljir2; !' Y Y _ 111.1•• . r .}•' �' 1 41 ";!: nt~ '•y '.'4}F,f.f:f i1•. �. •l .r l.t L'`.',7 +;• l •�� .. 1ti ggdd'� rlk-fse:N� _�I-' -:., tt. •� �', • • -; R • `r'�,' '!�•� r r:. '} ` •` - gT;•: r Lr�� 4671 �,. ".� ,'• .y [ilii r ..�s Ci J, aXy IA,.Igsb , Ttsh I `; `'.ti ,y� NORTH • JJ � '' "L.. � �`'� ,��•'�� ,c� .... ' fir',/ Tgab 1ti ' rlg + • rgww r " r19 Daie: 7/25/2014 Legend Approximate Scale t to = 2,000 ft iDrawn by: EKR Base map: Beeson, M. H., Tot an. T-L., and Mad in, 1. P., 1989, Geologic map of the Lake Oswego Quadrangle, Clackamas, Multnomah, and Washington Counties, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-59, scale 1:24,000. Project: Freepons Village Project No. 14-3393 FIGURE 1A Lake Oswego, Oregon 89 1 14835 SW 72nd Avenue GeoP f C Portland, Oregon 97224 Tel: (503) 598-8445 Fax. (503) 941-9281 JV w� Ito SUBJECT SITE ' • I / 24 VICINITY MAP • „N,� Hio Resolution digital elevation maQemi, 2014), + ► ' �� { `' �. @-J SUBJECT SITE ,�•' "`'�i}.� �s I .Rio Y 1 • f r t. `I MAPPED LANDSLIDES IF ,,o h High resolution digital elevation map with map ed landslides {�vgami. 214} " t ., .i Project: Freepons village Project No. 14-3428 FIGURE 113 Lake Oswego, Oregon 90 I Z 0 DQ Q 0 Z -j J Z ao W N 0 L x W Q rn n LU cn � ¢ N U U) W LL IL �tl X 7 ; _ -�_ �— •fir + I1r I I � ` - `� �-• R:I LL ji CL co �� -'' :ti's, r' �f.�l"� • � � " �,� ,� # �� ,.,� CL N T .Flu', �.� 1'�I • � y � �i� III i p I,"I' Y'�j I �"1; � � i� � � � •� f f � r 1 Q � � iy I I I �� 'IT� i � � � - + r■ r � 'i. 'sari OAti f c I _ 00' g ; . o r irva 5s�CL CLI � i rC%l LLgnC IMID coAll A, 91 a 00 a m CL U. •0 O J� � � 91 14835 SW 72nd Avenue 6eoPffie Portland, Oregon 97224 Tel: (503) 598-8445 Fax: (503) 941-9281 CD a o a co (0 M N N I I PROPERTY LINE — GABION WALL HA -3 (PROJECTED) _. RETAINING WALL ),f WMI PROPERTY LINE �11110 a C3 a It N a N N N Q � i 1 i m N N N CNV CSV GEOLOGIC SECTION a v OO CD r r i� F .. J uJ w LL z w C 2 Qo w IL -i a W q Project: Freepons Village Project No. 14-3393 Date: 7/25/2014 FIGURE 3 (Lake Oswego, Oregon Drawn by: EKR 92 _ 14835 5W 72nd Avenue GOP dific Portland, Oregon 97224 TEST PIT LOG Tel: 1503) 598-8445 Fax: (503) 941-9281 Project: Freepons Village Project No. 14-3393 Test Pit No. TP- 3 Lake Oswego, Oregon m 8 n T Y'Ln 2' CD ❑ N a. qCLo d=� .� Material Description o 9— G'' 0 O U a rn m Low to moderately organic SILT (OL -ML), brown, fine roots throughout, loose, Moist (Topsoil) 1 1.5 ----------------------------------------- --------------------------------.-____—_Stiff Stiffto very stiff, clayey SILT (ML), light brown, micaceous, trace fine roots, strong orange and gray mottling, trace black staining, moist {Loess} 2- 2.5 3 - 4.5 ---------------------------------------- Stiff to very stiff, clayey SILT (ML) to silty CLAY (CL), trace sand, light brown, micaceous, partially cemented, subtle orange and gray mottling, trace black 4- 4.5 staining, moist (Residual Soil) 5 Test Pit Terminated at 5 Feet for Infiltration Testing. 6 Note. No seepage or groundwater encountered. 7- 8- 10 11- 12 - LEGEND Date Excavated: 5/14/2014 ,autos ® -7 Logged By: B. Rapp 77 ooQ Surface Elevation: Bag Sample Buc'ses Sample Shelby Tube Sample Seepage Waler Seaanq Zone Water Level at Abandenmenl 93 SW 72nd Avenue GeoP�74835 lflc Portland, Oregon 97224 TEST PIT LOG Tel: (503) 598-8445 Fax: (503) 947-9281 Project: Freepons Village Project No. 14-3393 Test Pit No. TP -4 Lake Oswego, Oregon ZF ARE d 47 11) 0 o CL-?--� a 6,2 �= Materia[ Description m Low to moderately organic SILT (DL -ML), brown, fine roots throughout, loose, moist (Topsoil) 1 2.5 ------------------_--------------------- 2 -- 2.0 3 2.0 Stiff to very stiff, clayey SILT (ML) to silty CLAY (CL), trace sand, light brown, micaceous, partially cemented, subtle orange and gray mottling, trace black 4-- 2.0 staining, moist (Residual Soil) 5 - 6- 7- 8 Test Pit Terminated at 8 Feet for Infiltration Testing. 9 Note- Groundwater seepage encountered at 3 and 5 feet. 10 Discharge visually estimated at less than 112 gallon per minute. 11 12-- 2--LEGEND LEGENDn Date Excavated: 5/14/2014 '.ov uckal 1771 77 Logged By: B. Rapp Surface Elevation: Bag Sample Bickel Sample Shelby Tube Sample Seepage Wg:er Dearpl? Zone Water Level at Abandonment 94 5W 72nd Avenue g®ppn14835 g Portland, Oregon 97224 HAND AUGER LOG Tel: (503) 598-8445 Fax: (503) 941-9281 Project: Freepons Village Project No. 14-3393 Hand Auger No. HA -1 Lake Oswego, Oregon £p d) t V N a= o y E yN Q V C 4 M Material Description 47 O � CJ 0.1 f3 LIS M Moderately organic SILT (OL -ML), brown, fine roots throughout, loose, moist (Topsoil) 1 ----------------------------------------- 2 Stiff to very stiff, clayey SILT (ML) to silty CLAY (CL), trace sand, light brown, micaceous, strong to subtle orange and gray mottling, trace black staining, moist (Residual Soil) 3 4 5 - Hand Auger Boring Terminated at 5 Feet for Infiltration Testing. 6 - Note: No seepage or groundwater encountered. 7 8- 9- 10- 11 12 -- LEGEND Date Excavated: 5/14/2014 ,0010 5 'I ® 7 Logged By: B. Rapp Surface Elevation: Bag Sample Bucke! Sample Shelbv'rube Sample Seepage Waler Bearing Zone Waley Level at Abandonment 95 I'll 14835 SW 72nd Avenue Giop� rinc► Portland, Oregon 97224 HAN D AU G E R LOG Tel: (503) 598-8445 Fax: (503) 941-9281 Project: Freepons Village Lake Oswego, Oregon Project No. 14-3393 Hand Auger No. HA -2 9 E N N? 7 C O L a 'r� i77 o- a� o E (n N s a . �^' C "i pl Material Descriptions o ? go U a v� m Moderately organic SILT (OL -ML), brown, fine roots throughout, loose, moist (Topsoil) 1_ ---------------------------------------- Medium stiff to very stiff, clayey SILT (ML) to silty CLAY (CL), trace sand, light 2- brown, micaceous, strong orange and gray mottling, trace black staining, moist (Residual Soll) 3- 4- Hand Auger Boring Terminated at 3.5 Feet for Infiltration Testing. 5 Note: No seepage or groundwater encountered. 6- 7 8- -910- 9- 10- 12 12 LEGEND Date Excavated: 5/14/2014 9Coo 5 , ® Logged By: B. Rapp Surface Elevation: Bag Sample Bucket Samote Shelby Tube Sample Seeoage Water Hearing Zone Water Level at Abandonment 96 14835 5W 72nd Avenue ilPortland, Oregon 97224 HAND AUGER LOG SBOPrif fi MAW WJJMT-Rljt� Tel: (503) 598-8445 Fax: (503) 941-9281 Project: Freepons Village Lake Oswego, Oregon Project No. 14-3393 Hand Auger No, HA -3 9 07 �^ T .N _ y a°• p a U O41 a o a E �+ G �` a m= Material Description m - Medium dense to dense, silty GRAVEL (GM), gray, moist (Fill) 1 ------------------------------------------- 2 Stiff, clayey SILT (ML) to silty CLAY (CL), light brown, strong orange and gray - mottling, micaceous, moist (Fill) 3 4 --------------------------------------- 5 Soft, clayey SILT (ML) to silty CLAY (CL), trace subrounded to subangular gravel, brown, trace inorganic debris, strong to subtle orange and gray mottling, 6-. trace black staining, moist (Fill) 7 Modera—tely organic 51LT SOL -ML}, trace clay, gray, trace fine roots, moist — [Buried Topsoill—_.----------------------------- 8 Stiff, clayey SILT (ML) to silty CLAY (CL), trace sand, light brown to gray, strong to subtle orange and gray mottling, trace black staining, moist (Residual Soil) 9- 10 Hand Auger Boring Terminated at 10 Feet. 11— Note: No seepage or groundwater encountered. 12 LEGEND a Date Excavated: 5/14/2014 roolo 5„, 77 Logged By: B. Rapp ooa � Bag Sample OUckelSample Shelby Tube Sample Seepage Water Been rig Zone Water Laval al RGandonmenl Surface Elevation: 97 98 ai�-, p�C Real -World Geotechnical Solutions Investigation • Design • Construction Support September 24, 2014 Project No. 14-3393 Roger Edwards Silver Oak Custom Homes 14102 Goodall Road Lake Oswego, OR 97034 CC: ,Jon Morse - AKS Engineering $ Forestry, 'onm aks-en .cam SUBJECT: ADDENDUM TO GEOTECHNICAL REPORT FREEPONS VILLAGE 858 CEDAR STREET LAKE OSWEGO, OREGON REFERENCES: 1. Geotechnical Report, Freepons Village, 850 Cedar Street, Lake Oswego, Oregon, Revised August 19, 2014. 2. City of Lake Oswego, Planning and Building Services, Completeness letter by Jessica Numanoglu, dated September 18, 2014. This addendum letter has been provided to address items 6b and 6c of the City's Completeness letter by Jessica Numanoglu, dater! September 18, 2014. Item 6b: The relocation of the existing public waterline currently located near the north end of the property near the fill slope is considered geotechnically feasible. The public waterline will be relocated within the new private access lane, which is preferable to its present location near the fill slope. The potential for adverse impacts from the move should be reduced. Item 6C: A significant portion of the fill slope that has failed is being removed per recommendations in the geotechnical report. The fill removal should greatly improve slope stability. Homes constructed on Lots 6 through 8 should be reviewed during foundation excavation to verify that no structures or utilities are constructed within or upon any unsuitable fill. Since the slope creep (sliding) is limited to the fill only, such precautions should prevent potential for adverse slope stability impacts. Within the limitations of scope, schedule and budget, GeoPacific attempted to execute these services in accordance with generally accepted professional principles and practices in the fields of geotechnical engineering and engineering geology at the time the report was prepared. No warranty, expressed or implied, is made. The scope of our work did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous or toxic substances in the soil, surface water, or groundwater at this site. 14835 5W 72" Avenue EXHIBIT F-5 Portland, Oregon 97224 LU 14-0046 - c�c eS 99 Freepons Village Subdivision Protect No. 14-3393 We appreciate this opportunity to be of service. Sincerely, GEOPACIFIC ENGINEERING, INC. P R ❑F��,sr INP^ Q OREGON .23 s D. EXPIRES- 09/30/20 James D. Imbrie, G.E., C.E.G. Principal Geotechnical Engineer 3393-Freepons Village GR Addendum ? GEOPACiFIc ENGINEERING, INC. 100 CPC Heal -World Geotechnical Solutions Investigation - Design - Construction Support October 17, 2014 Project No. 14-3393 Roger Edwards Silver Oak Custom Homes 14192 Goodall Road Lake Oswego, OR 97034 CC: Jon Morse - AKS Engineering & Forestry, ionm(dTaks-ena.com SUBJECT: RESPONSE TO COMPLETENESS LETTER FRIEEPONS VILLAGE 850 CEDAR STREET LAKE OSWEGO, OREGON REFERENCES: 1. Geotechnical Report, Freepons Village, 850 Cedar Street, Lake Oswego, Oregon, Revised August 19, 2014. 2. City of Lake Oswego, Planning and Building Services, Completeness letter by Jessica Numanoglu, dated September 18, 2014. 3. Addendum to Geotechnical Report, Freeponse Village, 850 Cedar Street, Lake Oswego, Oregon, dated September 24, 2014. 4. City of Lake Oswego, Planning and Building Services, Completeness Letter by Jessica Numanoglu, dated October 15, 2014. This response letter has been provided to address item 5 of the City's Completeness letter by Jessica Numanoglu, dated October 16, 2014, Item 5: The proposed waterline relocation will have no adverse impacts and is both geotechnically feasible and recommended. Within the limitations of scope, schedule and budget, GeoPacific attempted to execute these services in accordance with generally accepted professional principles and practices in the fields of geotechnical engineering and engineering geology at the time the report was prepared. No warranty, expressed or implied, is made. The scope of our work did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous or toxic substances in the soil, surface water, or groundwater at this site. 14835 SW 72ftl Avenue Portland, Oregon 97224 EXHIBIT F-6 LU 14-0046 - 3 101 Freepons Village Subdivision Project No. 14-3393 We appreciate this opportunity to be of service. Sincerely, GEOPACIFIC ENGINEERING, INC. EXPIRES: oe/30/204- James D. Imbrie, G.E., G.E.G. Principal Geotechnical Engineer 102 3393-Freepons Village GR Response to Waterline 2 GEoPACTIC ENGINEERING, INC. DATE: CLIENT: ENGINEERING CONTACT: October, 2014 (Revised) Silver Oak Custom Homes Monty Hurley, PE, PLS ENGINEERING FIRM: AKS Engineering & Forestry, LLC. CITY OF LAKE OSWEGQ FILE No.: PA 14-0024_ z AKS JOB No.: 3845 KIK �ll ENGINEERING & FORESTRY 12965 5W Herman Road, Suite 100 Tualatin, OR 97062 P: (503) 563-5151 www.aks-eng.com OCT 2aZ014 EXHIBIT F-7 LU 14-0046 103 104 ENGINEER'S CERTIFICATION As the design engineer for the above mentioned development project, T hereby certify that the stone water management facilities have been designed in accordance with the Lake Oswego Drainage Design Manual. The technical information and data contained in this report was prepared under the direction and supervision of the undersigned, whose seal, as a professional engineer licensed to practice as such, is affixed below. fl� �( s41F I_ _ u %,�\ -�00i Y — aC ki y RENEWAL DATE: 6130115 '�&KS ENGINEERING & FORESTRY 12965 SW Herman Road, Suite 100 Tualatin, OR 97062 P. (503) 563-6151 www.aks-eng.com A ��. 1 `• tl �jr�rr QJ. TABLE OF CONTENTS PURPOSE STATEMENT PROJECT OVERVIEW LOCATION SOIL CLASSIFICATION EX I STING SITE PROJECT OVERVIEW IMPERVIOUS AREA CALCULATIONS EXISTING DRAINAGE CHARACTERISTICS ON-SITE DRAINAGE CHARACTERISTICS UPHILI, DRAINAGE CHARACTERISTICS DOWNHILL DRAINAGE CHARACTERISTICS INFILTRATION PROPOSED DRAINAGE CONVEYANCE SYSTEMS ON-SITE CONVEYANCE UPHILL CONVEYANCE DOWNSTREAM CONVEYANCE SURFACE WATER QUALIFY FACILITIES STORMWATER DETENTION FACILITIES APPENDIX 1-1 VICINITY MAP AND BASIN MAPS APPENDIX 2-1 DETENTION SYSTEM TYPICAL DETAIL. APPENDIX 2-2 PLANTER BOX DESIGN APPENDIX 2-3 SWALE CROSS SECTIONS APPENDIX 3-1 LAKE OSWEGO DETENTION VOLUME WORKSHEET APPENDIX 3-2 LAKE OSWEGO ORIFICE DIAMETER WORKSHEET APPENDIX 4-I WATER QUALITY CALCULATIONS APPENDIX 5-1 SWALE CALCULATIONS FOR POST -DEVELOPED "WORST CASTE" (ASSUMES NO INFILTRATION) 25 -YEAR STORM APPENDIX 6-1 SOIL INFORMATION APPENDIX 7-1 RUNOFF CURVE NUMBERS CHART APPENDIX 8-1 GEOTECHNICAL REPORT WITH INFILTRATION TEST RESULTS APPENDIX 9-1 DOWNSTREAM ANALYSIS INFORMATION 105 PURPOSE STATEMENT ■ Show compliance with all City of Lake Oswego drainage requirements and design criteria. • Provide factual data, field investigation reports, calculations, maps, drawings, cross- sections, analysis, and other information needed to support and verify the findings and conclusions of the drainage report. • Describe and show all existing on-site drainage conditions. • Describe and show all on-site and offsite adverse drainage impacts of the development. • Provide the conceptual drainage plan needed to mitigate the drainage impacts of the development. • Provide evidence (plans) that the proposed drainage system and facilities will meet required design criteria; will fit on the site; and will avoid, if possible, or minimize destruction or loss of natural resources. • Provide design criteria needed to prepare construction plans and specifications. PROJECT OVERVIEW 1WKWIN093,1A The site includes Tax Lots 5200, 5201, 5300, 5400, and 5401 of Clackamas County Tax Map 21 E010DC, which is at the east end of the Cedar Street cul-de-sac approximately 100 feet east of Bickner Street in Lake Oswego, Oregon. The site address is 850 Cedar Street, Lake Oswego, OR. SOIL CLASSIFICATION. - The NRCS soil survey of Clackamas County, Oregon classifies the onsite soils as Cascade silt loam. The associated hydrologic group of this soil is C. Hydrologic soil group C was used for all calculations. EXISTING SITE: The site is currently occupied with a single-family residence on existing tax lot 5200 (which will be removed) and associated improvements (all of which will be removed). PROJECT OVERVIEW', This project consists of an 8 -lot subdivision. The total area for this site is approximately 2.19 acres. Eight new single family residential homes with associated driveways and improvements and an access lane will be constructed. Stormwater runoff for each new home will be managed through the use of private stonnwater facilities. New homes will utilize vegetated planter boxes to meet the City's water quality requirements and an underground detention facility in the private access lane will be installed to meet detention requirements. Driveways for homes will either drain into the street side bioswales or the vegetated planter boxes on the lots. Stormwater runoff from the private access lane will be collected in street side bioswales and conveyed to a detention pipe or drain into a vegetated planter box, A portion of the paved 106 turnaround at the east end of the private access lane will not drain into the bioswaie or vegetated planter boxdue to topographic/grading constraints. Surface runoff from this small area of pavement (approximately 2,000 square feet) will be conveyed to a catch basin at the east end of the private access lane before being routed to the detention pipe. The catch basin will have a 24 -inch sump and a pollution control elbow, as recommended by City Engineering Staff. Discharge from the detention pipe will be conveyed to the existing public stormwater system located in the Cedar Street right-of-way. IMPER 1VIO US AREA CALCULATIONS: This project will add approximately 12,369 square feet of impervious area, which includes eight single family residential homes with associated access drive, and driveways. (This assumes 3,000 sf of impervious area per lot for building roof and driveway.) IMPERVIOUS AREA TABLE PRE -DEVELOPED AREA FTS 8 HOMES (INCLUDE DWYS) CONDITION ACCESS DRIVE AREA (FT) BUILDINGS AND PAVED 34,209 SURFACES 21,840 TOTAL EXISTING 21,840 POST -DEVELOPED CONDITION AREA FTS 8 HOMES (INCLUDE DWYS) 24,400 ACCESS DRIVE 14,209 TOTAL NEW 34,209 NET = NEW -EXISTING NET IMPERVIOUS AREA = 12,359 SQUARE FEET 0.28 ACRES EXISTING DRAINAGE CHARACTERISTICS ON --SITE DRAINAGE CHARACTERISTICS: Currently, the site drains northeast to an existing stream channel and northwest toward the existing Cedar Street right-of-way. Stormwater not captured in Cedar Street or the existing stream channel sheet flows offsite to the north. Onsite slopes range from 0 to 70 percent, with a majority of the steeper slopes at the north end of the site. Most of the site has slopes around 10 percent. UPHILL DRAINAGE CHARACTERISTICS: The area uphill (south) of the site is Freepons Park which has a large landscaped lawn. Beyond the park are detached single-family residential homes with lawns and landscaped 107 yards. There is a delineated stream channel that enters the site at the southeast comer and flows approximately 70 feet north to a ditch inlet. The upstream basin area draining to the stream is approximately 25 acres. DOWNHILL DRAINAGE CHARACTERISTICS: The site has a high point near the middle and drains northeast to an existing stream channel and northwest toward the existing Cedar Street right-of-way. Cedar Street is paved with curbs and catch basins in the cul-de-sac. The existing stream channel delineated in the northeast corner of the site terminates at a ditch inlet located at the north property line. From there. the stormwater is conveyed to the public stormwater system. INFILTRATION: The geotechnical infiltration test report in Appendix 8-1 recommends that storm related runoff is collected and disposed of off-site. The project geotechnical engineer does not recommend the use of open detention or stormwater infiltration facilities due to the low permeability of the soils, sloping topography, and potential for impacts to slopes. PROPOSED DRAINAGE CONVEYANCE SYSTEMS ON-SITE CONVEYANCE: Roof drains for each of the new homes will be routed to vegetated planter boxes, located on each lot. Each vegetated planter box shall be installed with the individual building permits for each home. The stormwater will then be conveyed to the underground detention facility located at the west end of the private access lane. Individual vegetated planter boxes have been designed and sized to treat stormwater runoff for water quality, as required by the City. An average impervious roof area of 2,500 square feet was used for the stormwater calculations. The vegetated planter boxes have been designed to overflow stormwater runoff in excess of the water quality storm event. Overflow runoff is conveyed to the private storm drain line. The vegetated planter boxes have been sized per the City of Portland Presumptive Approach Calculator (PAC) sizing methodology (Appendix 4-1). The vegetated planter boxes exceed the minimum required size based on the City of Portland Simplified Method of facility sizing (6% of impervious roof area). A new private storm drain line located in the private access lane will collect all onsite stormwater runoff from each of the lots. stormwater from the vegetated planter boxes, the shared access lane bioswale, and the catch basin at the end of the turnaround will be collected in the private storm drain line and be conveyed to the new underground detention facility located at the west end of the private access lane. From the underground detention facility, the stormwater is then conveyed through a flow control manhole to the existing public stormwater system Iocated in the Cedar Street right-of-way. Stormwater runoff from the access drive (excluding paved turnaround and west end) and driveways (excluding lot .5 driveway) will drain into the bioswale along the north side of the access drive. Driveways for lots 6-8 will be graded to drain to the bioswale. The 108 bioswale driveway culverts have been designed to convey stormwater runoff per City requirements. Swales conveying a contributing area of less than 40 acres shall convey a 25 -year storm and culverts shall convey a I0 -year storm. The bioswale has been designed to convey stormwater runoff from the 25 -year storm event to the detention facility where it will be detained per City requirements and then discharged to the public storm system. The west portion of the private access lane cannot drain to the bioswale due to topographic constraints. Stormwater runoff from this portion of the private access lane will be conveyed to a vegetated planter box where it is treated and then conveyed to the stormwater main located within the private access lane, A portion of the paved turnaround at the east end of the private access lane will not drain the bioswale due to topographic/grading constraints. The stormwater runoff from the lot 5 driveway cannot be conveyed to the bioswale due to topographic/grading constraints. Surface runoff from this driveway will be conveyed to the private vegetated planter box on lot 5 and then routed to the detention pipe. Each lot has been provided an individual private storm drain lateral for an overflow from the individual vegetated planter box that will be on each lot. UPHILL CONVEYANCE: There is a delineated stream channel that enters the site at the southeast corner and bows approximately 70 feet north to a ditch inlet connecting to the public storm system. Based on GIS information, the upstream basin area draining to the stream is approximately 25 acres. DOWNSTREAM CONVEYANCE: See Appendix 9-1 for downstream analysis information. SURFACE WATER QUALITY FACILITIES Stormwater quality facilities shall remove 65% of the phosphorous from 100 percent of the "newly constructed impervious surfaces." The treatment design storm for all surface water quality facilities shall be the mean summertime storm event totaling 0.36 inches of precipitation falling in 4 hours with an average return period of 96 hours, Stormwater runoff from the single-family residences will be routed to vegetated planter boxes where it will be treated for water quality, A vegetated planter box located at the northwest corner of the site will treat stormwater runoff from a portion (approximately 3,500 square feet at the west end) of the private access lane that is not able to drain to the bioswale due to topographic constraints. The stormwater runoff from the lot 5 driveway cannot be conveyed to the bioswale due to topographic/grading constraints. Surface runoff from this driveway will be conveyed to the private vegetated planter box on lot 5 and then routed to the detention pipe. The vegetated planter boxes have been sized per the City of Portland PAC sizing methodology (Appendix 4-1). The vegetated planter boxes exceed the minimum required size based on the City of Portland Simplified Facility sizing method (6% of impervious roof area). 109 Stormwater runoff from the access drive (excluding paved turnaround and west end) and driveways (excluding lot 5 driveway) will drain into the bioswale along the north side of the access drive, where it will be treated for water quality. The new bioswale adjacent to the private access drive has been designed per the City's Biofiltration Swale Worksheet (Appendix 4-I ). The swale has been sized to provide the required water quality treatment for all impervious area draining to the facility. The City's worksheet calculated a minimurn required swale length of 48.6 feet. The bioswale adjacent to the private access Iane is approximately 104 feet in length (excluding driveways), which satisfies the City's water quality requirement. A portion of the paved turnaround at the east end of the private access lane will not drain the bioswale due to topographic/grading constraints. Surface runoff from this small area of pavement (approximately 2,000 square feet) will be conveyed to a catch basin at the east end of the private access lane before being routed to the detention pipe. The catch basin will have a 24 -inch sump and a pollution control elbow to address water quality, as recommended by City Engineering Staff. The new vegetated planter boxes, bioswales, and the sumpedltrapped catchbasin will satisfy the City's water quality requirements. STORMWATER DETENTION FACILITIES Detention volume shall be the maximum difference between the runoff volume for the 50 -year storm event from the post -developed site conditions and the runoff volume for the 10 -year storm event from the pre -developed site conditions. Stormwater runoff from the site (Basin Y-1) (see basin map in Appendix 1-1) will be collected in the private stormwater main and conveyed to the new underground detention facility located at the west end of the private access lane. A portion of the developed site (Basin Z) cannot be conveyed to the to the detention pipe due to topographic constraints. The underground detention system has been sized to over -detain to account for Basin Z. The underground detention facility will consist of a 48 -inch diameter storm pipe and a flow control outlet structure. Basins XP and Y-2 will remain largely undeveloped and will not be conveyed to the detention system. The required detention vola ne calculations have been provided using the City's "Detention Volume Worksheet" per the Surface Water Management Design Manual. The required detention volume for Basin Y-1 and Basin Z have been calculated in separate Detention Volume Worksheets (Appendix 3-1). The required detention volume for basin Y-1 per the City's Detention Volume Worksheet is 736 cubic feet. The required detention volume for Basin Z is 83 cubic feet. Since Basin Z cannot be routed to the detention pipe, the calculated detention volume (83 cubic feet) was added to the calculated detention volume for Basin Y-1 (736 cubic feet), for a total detention volume of 819 cubic feet. The new underground detention system 110 will consist of approximately 66 lineal feet of 48 -inch diameter detention pipe which is equivalent to 829 cubic feet. Therefore, the City's detention requirements will be met. The allowable stormwater release rate for the site has also been calculated using the City's "Detention Volume Worksheet" per the Surface Water Management Design Manual. The allowable release rate is equivalent to the 10 -year pre -developed runoff rate. The allowable release rate for Basin Y-1 based on the City's Detention Volume Worksheet is 0.85 cubic feet per second (cfs). The allowable release rate for Basin Z based on the City's Detention Volume Worksheet is 0.11 cubic feet per second (cfs). Since Basin Z cannot be routed to the detention system, the discharge rate from the detention facility needs to be reduced accordingly. The allowable release rate for the site is calculated in the table below. Additional information is provided in Appendix 3-1. *Basin Z is not conveyed to the detention system. Therefore the release rate from the detention pipe should be reduced by 0.12 cfs. Allowable Release rate for the post developed 50 -year storm event is equal to: (0.85)cfs + (0.11)cfs — (0-12)cfs = 0.84 cfs The flow control orifice size was determined using the City's Orifice Diameter Worksheet (Appendix 3-2), The worksheet yielded an orifice diameter of approximately 3.9 inches. The calculated orifice diameter limits the release rate from the detention pipe to a maximum of 0.83 cubic feet per second, which is less than the allowable 0.84 cubic feet per second. Therefore, the detention facility will meet the City's detention requirements. 111 10 -YEAR PRE- 50 -YEAR POST CALCULATED BASIN DEVELOPED DEVLOPED DETENTION RUNOFF (cfs) RUNOFF (cfs) VOLUME (cf) Y-1 0.85 0.92 736 Z 0.11 0.12* 83 *Basin Z is not conveyed to the detention system. Therefore the release rate from the detention pipe should be reduced by 0.12 cfs. Allowable Release rate for the post developed 50 -year storm event is equal to: (0.85)cfs + (0.11)cfs — (0-12)cfs = 0.84 cfs The flow control orifice size was determined using the City's Orifice Diameter Worksheet (Appendix 3-2), The worksheet yielded an orifice diameter of approximately 3.9 inches. The calculated orifice diameter limits the release rate from the detention pipe to a maximum of 0.83 cubic feet per second, which is less than the allowable 0.84 cubic feet per second. 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Provide protection fmm ail vehicle traffic, equipment staging, 7 and foot traffic in proposed infiltration areas prior to, during, and after construction. 2. Dimensions: a. Width of flow-through planter. 18' minimum. b. Width of infiltration planter: 30' minimum. c. Depth of planter (from top of growing medium to overflow elevation); Simplified: IT , Presumptive: 6°-18'. d. Longitudinal slope of planter. 0.5% or less. 3. Setbacks (from centerline of facility): a. Infiltration planters must be 10' from foundations and 5' from property lines. L Flow-through planters must be less than 30' in height above surrounding area if within 5 -feet of property line. 4. Overflow: a. Overflow required for Simplified Approach b. fniet elevation must allow for 2' of freeboard, minimum, c. Protect from debris and sediment with strainer or grate. 5. Piping: shall be ABS Sch.401 cast iron, or PVC Sch.40. 3' pipe required for up to 1,500 sq ft of impervious area, otherwise 4 min. Piping must hove 1% grade and follow the Uniform Plumbing Code. 12' (3/8' TO 3/4i WASHED DRAIN ROCK OR OTHER APPROVED MATERIAL 30 MIL PVC LINER OR EQUIVALENT ABOVE PLANTER BASE WHEN REQUIRED Separation between drain rock and growing medium: Use filter fabric (see SWWM Exhibit 2-4 Geotextiie table) or a gravel lens (3/4- 1/4 inch washed, crushed rock 2 to 3 inches deep), B. Growing medium: a. til• minimum b. See Appendix F.3 for topsoil specificatlon or use sand/foam/compost 3 -way mix. 9. Vegetation: Fallow landscape plans otherwise refer to plant list in SWMM Appendix F. Minimum container size is 1 gallon, # of plantings per 100sf of facility area: Zone A (wet): a. 115 herbaceous plants OR; b. 100 herbaceous plants and 4 small shrubs. 10. Pianter walls: a. Material shall be stone, brick, concrete, wood or other durable material (no chemically treated wood). b. Concrete, brick, or stone walls small be included on foundation plans. 11. Waterproof liner. Shall be 30 mil PVC or equivalent for flow-through facilities. 12. Install washed peo gravel or river rock to transition from inlets and splash pad to growing medium. 6. Drain rock: 13. Inspections: Call BDS IVR Inspection Line, (503) 823-7000, a. Size for infiltration planter: 1-1/7 - Ve washed for appropriate inspections. b. Size for fined, flow-through planter. 3/4 washed e. flepth for Simplified: 12' d. Depth for Presumptive: 0-48' , see calcs. - DRAZING NOT TO SCAU - STDRMWATER MANAGEMENT TYPICAL DETAILS — Simplified / Presumpt;ve Design Approach — NUMBER Planter SW ---130 %wean of &vironmenW Services Go A A M N w 0 z W CL CL (A z 0 U W (A W J a 3 121 L.� S C.7 J Q 7C y�j Q 7 U cwt LY 4 c n LLJr CL s 122 U Q W Y � U Z d W [r O W LIS N M O U N C' � Z W � Q CD I J a " N w CD 0 �W V a w Z J CP] coLU LU xCL x 0 z W CL a a Z O H Z W H W D 0 LP)W 3 0 W Q J W J 0 i 123 DETENTION VOLUME WORKSHEET !ctName: Free ons Village Project Number; puted By: .1MM Date: pany; AKS Engineering & Forestry 'ess: 12965 SW Herman Road, Suite 100 e Numbers: (503) 563-6151 A. Re uired Release Rate. (10- Year Storm for existing pre -developed site) l 15 0 feet W flow length, feet 16 0.00 feet (D) drop over the flow length, feet l 7 0.000 ft./ft (S) Slope of overland flaw line, feet per foot. = D/L 18 0,00 Open channel description. (chart 8) l9 0.000 (n.) Manning's Roughness (chart 8) 20 0.000 ft/sec (V) Use Manning's equation to calculate flow velocity. (chart 1) 21 0.00 min. Time of Concentration 00 Tc = W50V 22 22.58 min. (Tc) Total Time of Concentration (line 9 + line 14 + line 21) 1 7/30/20141 231 1.39 acres (A) Total Site Area ? 0% to 10° a Im er. B. Developed Site Runoff Existing Land Use (ch art 10) 3 0.53 Acres (C) Runoff Coefficient {ch art 1Q) Sheet Flow Acres Use Mannings Kinematic solution for sh eel flow up to 300 feet. 4 267 feet (L) Longest overland Flaw Length 5 26 feet (D) Drop of Runoffalong Travel Route b 0.097 ft/ft {S} Slope of overland flow line, feet per foot, = D/L 7 Short grass 30F 736.45 Cu. Ft. Overland Flaw Description [ch art 8) 8 0.150 (n) Mannings Roughness (chart 8) 9 12.9x min_ (Te) Time of Concentration Te = 0.42 {n Lf" / 1.58 (S)0'4 Shallow Concentrated Flaw Use overland flow after the 300 foot maximum above. 0 65 feet (1,) flow length, feet 11 8 feat (D) drop over the flow length. feet 12 Q.123 ftlfl (5) Slope of overland flow line, feet per foot. = D/L 13 5.50 ft/sec (V) Use Chart 9 for unpaved slopes gre ater or equal to 0.005 ft./ft, 14 0.20 min. Time of Concentration (tc) Te L160V Open Channel Flow Use for defined channels. 231 l.l5 inlhr (1) Rainfall Intensity (chart 19) 24 0.85 cfs Peak Runoff Rate (pre -developed) Q = CIA B. Developed Site Runoff Coefficient. 25 0.72 Acres Impervious Area 26 0.67 Acres Pervious Area 27 0.30 Runoff Coefficient (C) for new Permeable Areas 2$ 0.61 C Composite Runoff Coefficient (line 25) X (0.91line 1) + (Iine26) X (line 271 line 1) 291 A X Cc Total Site Area (line 1) X Composite Runoff Coefficient (line 28) C. Required Detention Volume. 30F 736.45 Cu. Ft. Highest Volume From Detention Volume Work Sheet Page 1 124 DETENTION VOLUME WORKSHEET Project Name: Freepons Village City Project Number: 0 Date: A S C Storm 50 -year (A) (Cc) Duration Storm line 29 min. 1 nlhr 5 3.43 0.85 6 3.14 0.85 7 2.91 0.85 8 2.72 0.85 9 2.56 0.85 10 2.42 0.85 11 2.30 0.85 12 2.20 0.85 13 2.11 0.85 14 2.02 0.85 15 1.94 0.85 16 1.86 0.85 17 1.79 0.85 18 1.73 0.85 19 1.67 0.85 20 1.61 0.85 21 1.56 0.85 22 I.52 0.85 23 1.48 0.85 24 1.44 0.85 25 1.40 0.85 26 1.36 0.85 27 1.33 0.85 28 1.30 0.85 29 127 0.85 30 1.24 0.85 35 1.13 0.85 40 1.04 0.85 45 0.97 0.85 50 0.91 0.85 60 4.8I 0.85 90 0.64 0.85 120 0.53 0.85 D Inflow ($)(C) cfs 2.91 2.67 2.47 2.31 2.17 2.05 1.-95- T. 8- 51.87 I.79 1.71 1.65 1.58 1.52 1.47 1.42 1.37 1.32 1.29 1.26 1.22 1.19 1.15 1.13 1.10 1.08 1.05 0.96 0.88 0.82 0.77 0.69 0.54 0.45 E F 10 -year line 24 cfs Storage D - E cfs 0.85 2.06 0.85 1.82 4.85 I.62 0.85 1.46 0.85 1.33 0.85 .1.21 0.85 1.11 0.85 1.02 0.85 0.94 0.85 0.87 0.85 0.80 0.85 0.73 0.85 0.67 0.85 0.62 0.85 0.57 0.85 0.52 0.85 0.48 0.85 0.44 0.85 0.41 0.85 0.38 0.85 0.34 0.85 0.31 0.85 0.28 0.85 0.26 0.85 0.23 0.85 0.21 0.85 0.11 0.85 0.04 0.85 -0.02 0.85 -0.07 0.85 -0.16 0.85 -0.30 0.85 -0.40 Required Detention = Page 2 7/30/2014 G Detention Volume (A)(F)(60) 619.46 cu. ft. 654.72 cu. ft. 681.82 cu. ft. 701.80 cu. ft. 716.17 cu. ft. 724.43 cu. ft. 729.63 cu. ft. 734.83 cu. ft. 736.46 cu. ft. 728.93 cu. fL 719.87 cu. ft. 702.66 cu. fl. 685.96 cu. ft. 671.29 cu. ft. 650.51 cu. ft. 623.62 cu. ft. 601.32 cu. ft. 585.12 cu. ft. 564.85 cu. ft. 540.51 cu. ft. 512.09 cu. ft. 479.60 cu. ft. 456.78 cu. ft. 430.91 cu. ft. 401.98 cu. ft. 370.00 cu. ft. 235.55 cu. ft. 85.81 cu. ft. -63.92 cu. ft. -223.85 cu. ft. -574.25 cu. ft. -1,640.76 Icu. ft. -2,860.09 1 cu. ft. 736.46 cu.ft 125 DETENTION VOLUME WORKSHEET Project Name: Free ons Village (BASIN 2 OVER DETENTION City Project Number: Computed By: IMM Date: 912612 0 1 4 Company: AKS En ineerin & Forestry Address: 112965 SW Herman Road, Suite 100 Phone Numbers: (503) 563-6151 A. Re uired Release Rate. (10- Year Storm for existing pre -developed site) l 0.15 acres (A) Total Site Area 2 40% to 50% Im er. 25 Existing Land Use (chart 10) 3 0.55 0.04 Acres (C) Runoff Coefficient (chart 10) Sheet Flow Use Manning's Kinematic solution for sheet flow up to 300 feet. 4 138 feet (L) Longest Overland Flow Length 5 13 feet (D) Drop of Runoff along Travel Route b 0.094 ftlft (S) Slope of overland flow line, feet per foot, = D/L 7 ASPHALT DWY Overland Flow Description (chart 8) 81 0.018 (n) Mannings Roughness (chart 8) 91 1.42 min. (Tc) Time of Concentration Tc = 0,42 (nL)" 1 1.58 (S)" Shallow Concentrated Flow Use overland flow after the 300 foot maximum above. 10 0 feet (L) flow length, feet 1 l 0 feet (D) drop over the flow length, feet 12 #DIVIO! ftlfir (S) Slope of overland flow line, feet per foot. =D/L 13 0.00 ft/sec (V) Use Chart 9 for unpaved slopes greater or equal to 0.005 ft./ft. 141 #DMO! min. Time of Concentration (tc) Tc = LI60V Open Channel Flow Use for defined channels. 15 16 17 l8 19 20 21 22 ;et (L) flow length, feet .et (D) drop over the flow length, feet (ft (S) Slope of overland flow line, feet per foot. � D/L Open channel description. (chart 8) (n) Manning's Roughness (chart 8) ,sec (V) Use Manning's equation to calculate flow velocity. (chart 1) in. Time of Concentration (tc) Tc = L/60V in. (Tc) Total Time of Concentration (line 9 + line 14 + line 21) 131 1.15 in/hr (1) Rainfall Intensity (chart 19) 241 0.11 efs Peak Runoff Rate (pte-developed) Q = CIA B. Develo ed Site Runoff Coefficient. 25 0.10 Acres Impervious Area 26 0.04 Acres Pervious Area 2-7 0.30 Runoff Coefficient (C) for new Permeable Areas 28 0.70 C Composite Runoff Coefficient (line 25) X (0.91line 1) + (line26) X (line 271 line l ) 291 A X Cc Total Site Area (line 1) X Composite Runoff Coefficient (line 28) C. Required Detention Volume. 30J Cu. Ft. Highest Volume From Detention Volume Work Sheet Page 1 126 DETENTION VOLUME WORKSHEET Project Name: City Project Number: Freepons Village 0 (BASIN Z OVER DETENTION) Date: 9/26/2014 A B C ❑ E F G Storm Duration min. 50 -year Storm lnlbr (A) (Cc) line 29 Inflow (B) (C) cfs 10 -year line 24 cfs Storage D - E cfs Detention Volume (A) (F) (60) 5 3.43 0.10 0.35 0.11 0.24 72,33 cu. ft. 6 3.14 0.10 0.32 0.11 0,21 76,15 cu. ft. 7 2.91 0.10 0.30 0.11 0.19 78.98 cu. ft. 8 2.72 0.10 0.28 0.11 0.17 80.97 cu. ft. 9 2.56 0.10 0.26 0.11 0.15 82.27 cu. ft. 10 2.42. 0.10 0,25 0.11 0.14 82.85 cu. ft. 11 2.30 0.10 0.23 0.11 0.13 83.05 cu. ft. 12 2.20 0.10 0.22 0.11 0.12 83.26 cu, ft. 13 2.11 0.10 0.22 0.11 0.11 83.04 cu, ft. 14 2.02 0.10 0.21 0.11 0.10 81.71 cu, ft. 15 1.94 0.10 0.20 0.11 0.09 80.21 cu. ft. 16 1.86 0.10 0.19 0.11 0.08 77.72 cu. ft. 17 1.79 0.10 0.18 0.11 0.07 75.30 cu. ft. 18 1.73 0.10 0.18 0.11 0.07 73,11 cu. ft. 19 1.67 0.10 0.17 0.11 0.06 70.20 cu. ft. 20 1.61 0.10 0.16 0.11 0.06 66.55 cu. ft. 21 1.56 0.10 0.16 0.11 0.05 63.45 cu. ft. 22 1.52 0.10 0.16 0.11 0.05 61.09 cu. ft. 23 1.48 0.10 0.15 0.11 0.04 58.23 cu. ft, 24 1.44 0.10 0.15 0.11 0.04 54.89 cu. ft, 25 1.40 0.10 0.14 0.11 0.03 51.06 cu. ft, 26 1.36 0.10 0.14 0.11 0.03 46.74 cu. ft. 27 1.33 0.10 0.14 0.11 0.03 43.58 cu. ft, 28 1.30 0.10 0.13 0.11 0,02 40.05 cu. ft. 29 1,27 0.10 0.13 0.11 0,02 36.16 cu. ft. 30 1.24 0.10 0.13 0.11 0.02 31.89 cu. ft. 35 1,13 0.10 0.12 0.11 0.01 13.65 cu. ft. 40 1.04 0.10 0.11 0.11 0.00 -6.43 cu. ft. 45 0.97 0.10 0.10 0.11 -0.01 -26.52 cu. ft. 50 0.91 0.10 0.09 0.11 -0.02 -47.82 cu. ft. 60 0.81 0.10 0.08 0.11 -0.03 -94.11 Icu, ft, 90 0.64 0.10 0.07 0.11 -0.04 -234.80 Icu. ft. 120 0.53 0.10 0.05 0.11 -0.05 1 -393,85 Icu. ft. Required Detention = 83.26 cu. ft. Page 2 127 BASIN Z NOT DETAINED �Subcat Reach on Link 128 Y-1 BASIN Y-1 TO DETENTION SYSTEM 3845 BASIN Z ANALYSIS 50YR Prepared by AKS ENGINEERING Printed 10/17/2014 H droCADQ 8.50 sln 005096 CD 2007 H droCAD Software Solutions LLC Pa - e 2 Area Listing (all nodes) Area CN Description (sq -ft) (subcatchment-numbers) 31,454 74 GOOD CONDITION GRASS >75% COVER, HSG C (Y-1) 1.850 74 GRASS GOOD CONDITION X75% COVER, HSG C (Z) 29,059 98 IMPERVIOUS (Y-1) 4,475 98 IMPERVIOUS PAVEMENT (Z) 66,838 TOTAL AREA 129 3845 BASIN Z ANALYSIS 50Y Type 1A 24 -hr 50 -YR LAKE OSWEGO STORM Rainfall=4.20" Prepared by AKS ENGINEERING Printed 10/17/2014 HydroCADG) 8.50 sin 005096 Q 2007 HydroCAD Software Solutions LLC Page 3 Time span=5.00-20.00 hrs, dt=0.01 his, 1501 points Runoff by SBUH method, Split Perviouslimperv. Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentY-1: BASIN Y-1 TO Runoff Area=60,513 sf 48.02% Impervious Runoff Depth>2.27' Tc=5.0 min CN=74198 Runoff=0.92 cfs 11.465 cf SubcatchmentZ: BASIN Z NOT DETAINED Runoff Area -6,325 sf 70.75% impervious Runoff Depth>2.65" Tc=5.0 min CN=74198 Runoff=0.12 cfs 1,399 of Total Runoff Area = 66,838 sf Runoff Volume = 12,864 cf Average Runoff Depth = 2.31" 49.83% Pervious = 33,344 sf 50.17% Impervious = 33,534 sf 130 3845 BASIN Z ANALYSIS 50Y Type IA 24 -hr 50 -YR LAKE OSWEGO STORM Rainfall=4.20" Prepared by AKS ENGINEERING Printed 10/17/2014 H droCAD0 8.50 sln 00509E @2007 H droCAD Software Solutions LLC Pa - e 4 Summary for Subcatchment Y-1: BASIN Y-1 TO DETENTION SYSTEMA Runoff = 0.92 cfs @ 7.92 hrs, Volume= 11,465 cf, Depths 2.27' Runoff by SBUH method, Split Perviousllmperv., Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type IA 24 -hr 50 -YR LAKE OSWEGO STORM Rainfall=4.20" Area {sf) CN Descriotion 31,454 74 GOOD CONDITION GRASS >75% COVER, HSG C ' 29,059 98 IMPERVIOUS 50,513 86 Weighted Average 31,454 74 Pervious Area 29,059 98 Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft(ft/sec) cfs 5.0 Direct Entry, Subcatchment Y-1: BASIN Y-1 TO DETENTION SYSTEM Hydrograph 5 ti 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) L Runoff 131 3845 BASIN Z ANALYSIS SOY Type lA 24 -hr 50 -YR LAKE OSWEGO STORM Rainfall=4.20" Prepared by AKS ENGINEERING Printed 19/17/2014 H droCADO 8.50 sin 005095 0 2007 Fi droCAD Software Solutions LLC Page 5 Summary for Subcatchment Z: BASIN Z NOT DETAINED Runoff = 0.12 cfs @ 7.90 hrs, Volume= 1,399 cf, Depths 2.65" Runoff by SBUH method, Split Perviousllmperv., Time Span= 5.00-20.00 hrs, dt= 0.01 hrs Type IA 24 -hr 50 -YR LAKE OSWEGO STORM Rainfall=4.20" Area_(so CN Description 4,475 98 IMPERVIOUS PAVEMENT 1,850 74 GRASS GOOD CONDITION >75% COVER HSG C 6,325 91 Weighted Average 1,850 74 Pervious Area 4,475 98 Impervious Area Tc Length Slope Velocity Capacity Description min feet(ft/ft) ft/sec cfs 5.0 Direct Entry, Subcatchment Z: BASIN Z NOT DETAINED Hydrograph 0.13 0.125 Q.12 cfs 0.12 0.175 Type IA 24 -hr 50 -YR LAKE OSWEGO STORM 0.11 Rainfall=4.20" 0.105 Runoff Area=6,325 sf 0.1 Runoff Volume=1,399 cf 0.095 Runoff Deptha2.65" 0.09 0.085._ Tc=5.0 min 0.08 CN=74/98 a 0.075 D.07 3 0.065 0 0,08 - LL 0.055 0.05 0.045- 0.04 0.035 0.03 0.025 0.02 0.015- D.D1 0.005 _ 0 5 6 7 8 9 10 31 12 13 14 • 15 16 17 18 '19 20 Time (hours) 132 r1 Runoff ORIFICE DIAMETER WORKSHEET Project ame: City Project Number. Computed By: Company: Address: Phone Numbers: Freepons Village Date: I0116 2014 umch. I ' JMM AKS Engineering & Forestry 2965 SW Herman Road Suite 100 (503) 563-6151 Liuuei n,tructure Luenuncatzon: DETENTION PIPE ORIFICE Calculate the outlet orifice size for a given discharge Orifice Equation: Q = CAQ-h)" C = 0.62 g = 32.20 4.00 0.00 h = 4.00 feet Q=J 0.8400 cfs Coefficient of Discharge Accel. of Gravity (R.Isec.lsce.) overflow elevation invert elevation out (Height above overflow elevation to i.e. out) (Design Discharge from Detention Worksheet) Orifice Area: A = 0.084414 sq. ft. A — (QIC)(2gh)"" A = pi*R` R = 0.164 feet R = (Alpi)" Pi = 3.14159 D = 0.328 feet (R) 2 Orifice Diameter: D = 3.934 inches kuf",t) LL Calculate the discharge "Q" for a given orifice diameter. orifice diameter: 13=1 3.90[} inches provided D= 0.325 feet umch. I ' R = 0.163 feet (R)12 A = 0.0830 sq. ft. A = pi*R" 4.60 overflow elevation 0.00 invert elevation out h = 4.00 feet Q = 0.8255 c.f.s. CA(2gh)"' Page 1 133 H. Z W CL CL a 134 BI0FILTRATIQN SWALE WORKSHEET (undated October I. 19941 Project Name: City Project Number: Computed By: Company: Address: Phone Numbers: Free ons Village Date: 1 9/26/2014 LU 14-0046 'mm AKS Engineering & Forestry 12965 SW Herman Road, Suite 100 503-563-6151 Osq, ft./lot = New Impervious Area Calculation. Total Site Area: Post developed Basin Y-1 4.016 efs 0.17 acres (excludes paved turnaround area) Bottom Width: 7,47$ sq. ft. home sites: (to planter box) Olots @ Osq, ft./lot = sq. A. new buildings: 0.02 ft. Flow Top Width 01 sq- ft. newparking area: 0,09 ft./sec 0 sq. ft. sidewalk area: 0 feet long x feet wide = 0 sq. ft. street area: (includes dwys) 0 feet long x 20 feet wide = 7,478 sq. ft. other area: ®sq. ft. Total Impervious Area: 7,478 sq. ft. 0.17 acres percent Impervious area: 100% Design Flow Rate. Design Storm: 0.36 inches of rain falling in 4 hours. Calculate the volume to be treated. Vol. = (0.36)X( 1 ft./12 in.)X 7,478 sq. ft. = 224 cu. ft, imp. area volume Calculate the design flow rate over the 4 hour storm period. Flow rate = 224 cu. ft./(4 hrs. X 3600 sec.) = 0.016 cfs volume Trapezoidal Swale Characteristics. Design Flow Rate: 4.016 efs Manning's "n" value: 0.25 Bottom Width: 2.0 ft. Side Slopes (both sides) 3.0 H:1 V Channel Slope: 0.008 fLIft. Flow Depth 0.02 ft. Flow Top Width 8.00 ft. Flow Velocity: 0,09 ft./sec Required Swale Length. Calculate the swale length needed for the 9 minute residence time. (9 min.)X(60 sec./min.) X 0.09 ft./sec. = 48.6 feet (100 foot minimum) velocity 135 .:: Presumptive Approach Calculator ver. 1.2 Catchment Data `-'` Catchment iD: A Project Name: Freepons Villa a Date: 07130114 Project Address: 850 Cedar Street Permit Number: 4 Lake Oswego, OR Run Time Designer: Jonathon Morse Company: AKS Engineering Drainage Catchment Information Catchment ID I A Catchment Area Impervious Area 2,500 SF Impervious Area 0.06 ac Impervious Area Curve Number, CNimp 98 Time of Concentration, Tc, minutes 5 min. Site Soils & Infiltration Testing Data Infiltration Testing Procedure: L ❑ en Pit Failing Head Native Soil Field Tested Infiltration Rate (Fest]: 1.42 in/hr Bottom of Facility Meets Required Separation From High Groundwater Per BES SWMM Section 1.4: No Review Groundwater Depth with BES Correction Factor Component CFte31 (ranges from 1 to 3) 12 Design fnfiltration Rates Id,,, for Native �itest 1 CF4es1}: 0.71 inlhr Idsgn for Imported Growing Medium: I inlhr4W 2.00 0.0700 0.0600 0.0500 0.0400 0.0300 0 0.0200 0.0100 0.0000 -0.0100 �. Execute SBLJH SBUH Results PR 2-vr Peak Rate Volume cfs(CO Time [min.] Printed: 7/28/2014 2:29 PM 136 ,, Presumptive Approach Calculator Ver. 1.2 Catchment ID.� Run Time Project Name: Freepons Village Catchment ID: A Date: Instructions: 1. Identify which Stormwater Hierarchy Category the facility" 2" Select Facility Type, 3. Identify facility shape of surface facility to mare accuratety estimate surface Vatume, except for Swales and sloped planters that use the PAC Sloped Facility Worksheet to enter data. 4" Select type of facility configuration. 5. Complete data entry for all highlighted cells. Catchment facility will meet Hierarchy Category: Goal Summary: Ilirrorcky REst ILTS kxsx Brlum muds to display... ti►►►111 Rrquirempnr [-utcKnn� Pollution f0 -y -r (al:a dispmall Jnr 8.0 ft Reducriart as a 0 3 [ 1lf-mcc flo- Io dminngvu ay, rno-CF. or xlomi-011lyPipe 12 In Growing Medium Depth = System. VASS N -A Facility Type = Planter Flat Facility Shape: Rectangle)Square Facility Bottom Arca DATA FOR ABOVE GRADE STORAGE COMPONENT Facility Bottom Area = 200 sf Bottom width = 8.0 ft Facility Side Slope = 0 to 1 Storage Depth 1 = 12 In Growing Medium Depth = 18 In Freeboard Depth = N/A in Surface Capacity at Depth 1 = 200 cf GM Design Infiitration Rate = 2.00 Inlhr Infiltration Capacity= 0.009 Cfe Facility Configuration: D PLAN TER wi--0-SANE ❑ L__" Facility I —Storage Depth 1 Bottom Area l GM Depth x 7 waterproat GROWING MEDIUM Liner ROCK ~ -- -.Ov Aow C. _ Rock Storage Deptb ESULT5 Volume PWluUOR Reduction PA55 0 CF 0% Surf" Cap. Used utput File 2 -Yr 6 -yr 10 -yr 25- r Peak cfs 0.009 1 0.008 1 0.009 1 0049 BELOW GRADE STORAGE Rock Storage Capacity = Native Design Infiltration Rate = Infiltration Capacity = FACILITY FACTS Total Facility Area Including Freeboard = 200 5F Sizing Ratio [Total Facility Area 1 Catchment Area] = 0.080 I WIDITrL►1 cf inlhr cfs Current data has been exported: PAC Calc Pfanter Box 20140730.xis 7/2812014 2:28:55 PM Facility Design Data Calculation Guide Max Rock Stor Bottom Area 200 SF Printed: 712$12014 2:29 PM 137 138 + - l• I 1 � x cl En r n '•a9 LU = °s EN ' co EL O 3 J LO ch • + - l• I 1 � x LU = °s co EL O 3 J LO F 20 z Q LL z 0 U U w 2 0 Q L0 "i LL z 0 i3 U Q CL m A ;|2 J12 E 139 ■ 0 �- /� §PO h vt -- �. � �r\ Aj- kCN \� a� •� •!&< � ■ � & ; - � s; � ! m A ;|2 J12 E 139 BES - Presumptive Approach Calculator - Ver 1.2 Project Dame: Run Time: Catchment ID: Hierarchy: Facility Type: Facility Configuration: 0.0120 0.0100 0.0080 0.0080 3 LL 0.0040 0.0020 0.0000 -0.0020 Printed: 7/28/2014 2:29 PM 140 Pollution Reduction Event Surface Facility Modeling Inflow from Rain Event Percolation Capacity Percolation and Overflow to Approved Discharge % Surface Capacity TT 500 1000 1500 2000 2500 Time (min) 0% 10D% 200% LL LL 300% 400% 500% A� W 7 L G r� cv s c� D i Q. CL Q Q Q. E d i a W m Eat ao �m@� c 2? a, E EL (j 11 U T U L4 LL 0 0 0 v 0 0 0 O 0 0 0 0 0 0 0 0 iI- 0 0 C� C) C) O 0 0 ts;of mol j oezz 0912 OvOz OZ61 0081 o a E E 0991 ' s° T- � O p it O rn w O 0 in cn p p 1 0801 ,1 096 t N tf7 r N N 117 N t t 08v i •. t ' i `..•. OZ1 t � i t t t � i Eat ao �m@� c 2? a, E EL (j 11 U T U L4 LL 0 0 0 v 0 0 0 O 0 0 0 0 0 0 0 0 iI- 0 0 C� C) C) O 0 0 ts;of mol j 0 a 0 0 r Q 0 0 C> 0 0 0 I E E P 141 oezz 0912 OvOz OZ61 0081 0891 0991 ' ovvl i. i i it ii ON 1 0801 ,1 096 t ave i 1 1 1 OZL 009 08v i •. 09£ ' ObZ `..•. OZ1 0 a 0 0 r Q 0 0 C> 0 0 0 I E E P 141 x 0 z W CL CL Q 142 Cl ce uj Z 0 a LL. U J � H Z Z �O�C Z I- O V V D W J W 3�0 W W 1S PERVIOUS FROM LOTS 2R -v 1L 2S SWALE TO DETENTION PIPE IMPERVIOUS FROM PRIVATE ACCESS LANE AND DWYS 5ubcat Reach on Link 143 3845 swale Prepared by AKS ENGINEERING Printed 9/26/2014 Hi ydroCADD 8.50 stn 005096 © 2007 H ydroCAD Software Solutions LLC Page 2 Area Listing (all nodes) Area CN Description (sq -ft) (subcatchment-numbers) 25,000 74 PERVIOUS (1S) 7,478 98 iMPERViOUS {2S} 32,478 TOTAL AREA 144 3845 swale Type IA 24 -hr 25 -YR LAKE OSWEG0 STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 9/26/2014 HydroCAD® 8.50 sln 04509E 0 2007 HydroCAD Software Solutions LLC page 3 Time span=0.66-24.00 hrs, dt=0.01 hrs, 2401 points Runoff by SBUH method Reach routing by Stor-End+Trans method - Pond routing by Star -Ind method Subcatchmeint IS: PERVIOUS FROM LOTS Runoff Area=25,000 sf 0.00% Impervious Runoff Depth >1.45" Tc=5.0 min CN=74 Runoff=0.174 cfs 3,014 of 5ubcatchment2S: IMPERVIOUS FROM Runoff Area=7,478 sf 100.00% Impervious Runoff Depth>3.56" Tc=5.0 min CN=98 Runoff=0.153 cfs 2,218 cf Reach 2R: SWALE Avg. Depth=0.25' Max Vet=0.24 fps Inflow=0.322 cfs 5,233 cf n=0.150 L=175.0' S=0.0050 '1' Capacity=1.085 cfs Outflow=0.304 cfs 5.141 cf Link 1 L: TO DETENTION PIPE Inflow=0,300 cfs 5,141 of Primary=0.300 cfs 5,141 of Total Runoff Area = 32,478 sf Runoff Volume = 5,233 cf Average Runoff Depth = 1.93" 76.98% Pervious = 25,000 sf 23.02% Impervious = 7,478 sf 145 3845 swale Type 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 9/2612014 HydroCAD® 8.50 sln 005096 0 2007 HydroCAD Software Solutions LLC Pape 4 Summary for Subcatchment 1 S: PERVIOUS FROM LOTS Runoff - 0.174 cfs @ 8.00 hrs, Volume= 3,014 cf, Depths 1.45" Runoff by SBUH method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Area fsf] CN Descriotion 25,000 74 PERVIOUS 25,000 Pervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft) [ft/sec] _(cfs) _ 5.0 Direct Entry, Subcatchment 1S: PERVIOUS FROM LOTS Hydrograph 0 1 2 3 4 5 8 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 146 ❑ Runoff 3845 swale Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 9/26/2014 hE droCAD® 8.50 sln 005096 a 2007 H droCAD Software Solutions LLC Page 5 Summary for Subcatchment 2S: IMPERVIOUS FROM PRIVATE ACCESS LANE AND DWYS Runoff M 0.153 cfs @ 7.88 hrs, Volume= 2,218 cf, Depths 3.56" Runoff by SBUH method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Area (so CN Description _ 7,478 98 IMPERVIOUS 7,478 Impervious Area Tc Length Slope Velocity Capacity Description min feet) (ft/ft(ft/sec) cfs 5.0 Direct Entry, Subcatchment 2S: IMPERVIOUS FROM PRIVATE ACCESS LANE AND DWYS Hydrograph 0 1 2 3 4 5 B 7 8 9 10 11 12 13 14 15 16 17 18 19 26 21 22 23 24 Time [hours] C7 Runoff 147 3845 swale Type lA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 9/26/2014 H droCAD® 8.50 sln 005096 V 2007 H droCAD Software Solutions LLC Page 6 Summary for Reach 2R: SWALE Inflow Area = 32,478 sf, 23.02% Impervious, Inflow Depth a 1.93" for 25 -YR LAKE OSWEGO STORN Inflow = 0.322 cfs @ 7.96 hrs, Volume= 5,233 cf Outflow = 0.300 cfs @ 8.23 hrs, Volume= 5,141 cf, Atten= 7%, Lag= 16.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 0.24 fps, Min. Travel Time= 12.0 min Avg. Velocity = 0.13 fps, Avg. Travel Time= 22.1 min Peak Storage= 215 Of @ 8.03 hrs, Average Depth at Peak Storage= 0.25' Bank -Full Depth= 0.50', Capacity at Bank -Full= 1.085 cfs 4.00' x 0.50' deep channel, n= 0.150 Sheet flow over Short Grass Side Slope Z -value= 4.0'f Top Width= 8.00' Length= 175.0' Slope= 0.0050? Inlet Invert= 0.00', Outlet Invert= -0.88' t 148 Reach 2R: SWALE Hydrograph 0.36- 0,322 cfs 0.34`. 0.32 0.300 cfs Inflow Area=32,478 sf fl .3 Avg. Depth=0.25' 0-26 Max Vel=0.24 fps 0.24 0.22 n=0.150 D..1818 - L=175.0' � - n 0.16 S=0.0050 T 0.14- 0.12 Rapacity -1.085 cfs 0.1 D 1 2 3 4 5 6 7 S 9 10 11 12 13 14 15 18 17 18 19 20 21 22 23 24 Time (hours) ■ Inflow ❑ outflow 3845 swale Type lA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 9/26/2014 HydroCAD8 8.50 sln 005095 @2007 HydroCAD Software Solutions LLC Page 7 Summary for Link 1 L: TO DETENTION PIPE Inflow Area = 32,478 sf, 23.02% Impervious, Inflow Depth > 1.90" for 25 -YR LAKE OSWEGO STORN Inflow = 0.300 ifs @ 8.23 hrs, Volume= 5,141 cf Primary = 0.300 cfs @ 8.23 hrs, Volume= 5,141 cf, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Link 1 L: TO DETENTION PIPE Hydrograph ❑ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 0 Inflow Q Primary 149 7"1 0 z W CL 150 J H 0 USDA United States Department of Agriculture MRCS Natural Resources Conservation Service A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Clackamas County Area, Oregon FREEPGNS VILLAGE July 7, 2MA Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, orenhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (httpi//www.nres.usda.gov/wps/portal/ nreslmainlsoilslhealthl) and certain conservation and engineering applications_ For more detailed information, contact your local USDA Service Center (http:// offices sc. egov.usda.govllocatorlapp?agency=nres) or your NRCS State Soil Scientist (http llwww.nres.usda.govlwpslportallnrcsldeta illsoilslcontactusl? cid=nres142p2_053951 ). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey #nformation. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion. sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means 152 for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 independence Avenue, S.W., Washington, D.C. 2 025 0-9410 or call (8 00) 79 5-32 72 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 153 Contents Preface....... ....................................... reface.............................................. 2 How Sail Surveys Are Made ............................................ ....... .•-........................... 5 SoilMap .......................................... ....... ............. ......... ....... ................. .................. 7 SoilMap. ........ ........... .........................................-.....-......_.....................................8 Legend.........................................-_............................................................... ....... 9 MapUnit Legend...... .................................--........................................10 MapUnit Descriptions ..... ................... .................................. ---- ------ ............. 10 Clackamas County Area, Oregon ................. ..,.12 713—Borges silty clay loam, 0 to 8 percent slopes......................................12 13B—Cascade silt loam, 3 to 8 percent slopes...........................................13 13C—Cascade silt loam, 8 to 15 percent slopes ............ .... ........................ 14 92F—Xerochrepts and Haploxerolls, very steep.........................................15 Sail Information for All Uses.. ... .........................................................................17 Soil Properties and Qualities ............................ ............................. ................17 Soil Qualities and Features.............................................................................17 Hydrologic Soil Group (FREEPONS VILLAGE). ....................................... -17 SoilReports......................................................................... .................22 Soil Physical Properties...... ......................................................... .................22 Engineering Properties (FREEPONS VILLAGE)--, ...................... - .......... 22 References..... .................... ......... — ... -- .................................................... .......27 154 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soit profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil -vegetation -landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil scientists classified and named the soils in the survey area, they compared the 5 155 Custom Soil Resource Report individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure rnap unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each reap unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. if intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil - landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil -landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field -observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields underdefined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date_ After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. 156 6 Soil Map The soil reap section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. 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CL w m m m u y U > i6 7 a 2 � y v rn w rn N N T O h p '2 �1 m W E 2 •71 Sg ❑ lV O 0 L w a oO g L "UL w m y '0 u7 7 S O r7r o02 ES m y CL 9 W + r Y �� ''^^ V H m W J w IL Q Q rn Q p O o m N Y a rL n C [x [l 10 Q. ❑ ji En 0 ❑ LU N 0 Q Cl `C IL ❑ w T G O w L R ❑ 0 IC 7 = 0 {rL � N C •a �, y L [1 P 6f -� O m @ C_ [] 'E _ -3) y v 9A Q q VS O C VY fA '0 O m m 113 U U 0 W C U' J � � uPl � 2T Ll CC V] C7 5 C [ry w v [D LIS d E a m � 0 X - X � � � � � � e�� C N + w ® w Q N 159 0 Custom Soil Resource Report Map Unit Legend Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic 160 10 Clackamas County Area, Oregon (OR610) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 7S Borges silty day loam, 4 to 8 2.0 17.0% percent slopes 13B Cascade silt loam, 3 to a percent 6.2 52,8% slopes 13C Cascade silt loam, 8 to 15 2.6 22.4% percent slopes 92F xerochrepts and Haploxerolls 0.9 7,8%, very steep Totals for Area of Interest 11.7 100.0% . Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic 160 10 Custom Soil Resource Report classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam. 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the neap units in the survey area, It was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha - Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Same surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report Clackamas County Area, Oregon 7B --Borges silty clay loam, 0 to 8 percent slopes Map Unit Setting Elevation: 254 to 1,400 feet Mean annual precipitation: 48 to 65 inches Mean annual air temperature: 50 to 54 degrees F Frost -free period: 140 to 210 days Map Unit Composition Borges and similar soils: 80 percent Minor components: 6 percent Description of Borges Setting Landform: Hillslopes, depressions on terraces Landform position (two-dimensional).- Footslope Landform position (three-dimensional): Base slope, tread Down-slope shape: Linear Across -slope shape.- Linear Parent material- Clayey alluvium Typical profile H1 - ❑ to 18 inches: moderately acid, silty clay loam H2 - 18 to 45 inches: moderately acid, silty clay H3 - 45 to 60 inches: moderately acid, clay loam Properties and qualities Slope: 0 to 8 percent Depth to restrictive feature: More than 80 inches Natural drainage class. Poorly drained Capacity of the most limiting layer to transmit water (Ksat). low (0.00 to 0.06 in/hr) Depth to water fable: About 0 to 6 inches Frequency of flooding: None Frequency of ponding: None Available waterstorage in profile: High (about 10.4 inches) Interpretive groups Farmland classification: Farmland of statewide importance Land capability classification (irrigated): None specified Land capability classification (nonirrigated), 4w Hydrologic Soil Group: ❑ Minor Components Selena Percent of map unit: 6 percent Landform: Hillslopes, terraces Landform position (two-dimensional)-- Footslope Landform position (three-dimensional): Interfluve, riser Down-slope shape: Linear Across -slope shape: Linear 162 12 Very low to moderately Custom Soil Resource Report 13B—Cascade silt loam, 3 to 8 percent slopes Map Unit Setting Elevation: 250 to 1,400 feet Mean annual precipitation: 50 to 60 inches Mean annual air temperature: 50 to 54 degrees F Frost -free period: 165 to 210 days Map Unit Composition Cascade and similar soils: 80 percent Minor components: 3 percent Description of Cascade Setting Landform: Hillslopes Landform position (two-dimensional): Footslope, summit Landform position (three-dimensional).- Interfiuve, crest Down-slope shape: Linear Across -slope shape: Linear Parent material: Silty material Typical profile H9 - 0 to 11 inches: moderately acid, silt loam H2 - 11 to 21 inches: moderately acid, silt loam H3 - 21 to 60 inches: moderately acid, silty clay loam Properties and qualities Slope: 3 to 8 percent Depth to restrictive feature: 20 to 30 inches to fragipan Natural drainage class: Somewhat poorly drained Capacity of the most limiting layer to transmit water (Ksat). Moderately low to moderately high (0,06 to 0.24 in/hr) Depth to water table: About 18 to 30 inches Frequency of flooding: None Frequency of ponding: None Available wafer storage in profile: Low (about 4.0 inches) Interpretive groups Farmland classification: Prime farmland if drained Land capability classification (irrigated).- 3w Land capability classification (nonirrigated): 3w Hydrologic Soil Group: C Minor Components Delena Percent of map unit: 3 percent Landform: Hillslopes, terraces Landform position (two-dimensional): Footslope 13 163 Custom Soil Resource Report Landform position (three-dimensional): Interfluve, riser Down-slope shape: Linear Across -slope shape: Linear 13C—Cascade sift loam, 8 to 15 percent slopes Map Unit Setting Elevation: 250 to 1,400 feet Mean annual precipitation: 50 to 60 inches Mean annual air temperature: 50 to 54 degrees 1= Frost free period: 165 to 210 days Map Unit Composition Cascade and similar soils: 80 percent Description of Cascade Setting Landform: Hillslopes Landform position (two-dimensional): Summit, footslope Landform position (three-dimensional): Crest, interfluve Down-slope shape Linear Across -slope shape: Linear Parent material: Silty material Typical profile H1 - 0 to 11 inches: moderately acid, silt loam Flt - 11 to 21 inches: moderately acid, silt loam H3 - 21 to 60 inches: moderately acid, silty clay loam Properties and qualities Slope: 8 to 15 percent Depth to restrictive feature: 20 to 30 inches to fragipan Natural drainage class: Somewhat poorly drained Capacity of the most limiting layer to transmit water (Ksat).- Moderately how to moderately high (0,06 to 0.20 in/hr) Depth to water table: About 18 to 30 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Low (about 4-0 inches) Interpretive groups Farmland classification: Farmland of statewide importance Land capability classification (irrigated): 3e Land capability classfcation (nonirrigated): 3e Hydrologic Soil Group: C 164 14 Custom Soil Resource Report 92F--Xerochrepts and Haploxerolls, very steep Map Unit Setting Elevation: 56 to 1,600 feet Mean anneal precipitation. 40 to 6Q inches jWean annual air temperature: 50 to 54 degrees F Frost -free period: 165 to 210 days Map Unit Composition Xerochrepts and similarsods: 50 percent Haploxerolls and similar soils: 35 percent Description of Xerochrepts Setting Landform: Terraces Landform position (three-dimensional!: Riser Down-slope shape: Linear Across -slope shape: Linear Parent material: Colluvium derived from igneous rock Typical profile H - 0 to 8 inches. moderately acid, silt loam H2 - 8 to 48 inches: moderately acid, gravelly clay loans H3 - 46 to 60 inches: moderately acid, very cobbly clay loam Properties and qualities Slope: 20 to 60 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Capacity of the most limiting layer to transmit water (Ksaf). Moderately high (0.20 to 0.57 in/hr) Depth to wafer fable About 36 to 72 inches Frequency of flooding: !None Frequency of ponding: None Available wafer storage in profile: Moderate (about 8.0 inches) Interpretive groups Farmland classification: Not prime farmland Land capability classification (irrigated). Mone specified Land capability classification (nonirrigated): 6e Hydrologic Soil Group. B Description of Haploxerolls Setting Landform: Terraces Landform position (three-dimensional). Riser Down-slope shape: Concave Across -slope shape: Linear Parent material: Colluvium derived from igneous rock 15 165 Custom Soil Resource Report Typical profile H7 - 0 to 12 inches: moderately acid, silt loam H2 - 12 to 60 inches. moderately acid; very gravelly loam Properties and qualities Slope: 20 to 60 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.20 to 1.98 in/hr) Depth to water fable. About 36 to 48 inches Frequency of flooding: None Frequency ofponding: None Avaiiable water storage in profile: High (about 12.0 inches) Interpretive groups Farmland classification: Not prime farmland Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 6e Hydrologic Soil Group: B 166 '16 Soil Information for All Uses Soil Properties and Qualities The Soil Properties and Qualities section includes variaus soil properties and qualities displayed as thematic maps with a summary table For the soil map units in the selected area of interest. A single value or rating for each map unit is generated by aggregating the interpretive ratings of individual map unit components. This aggregation process is defined for each property or quality. Soil Qualities and Features Soil qualities are behavior and performance attributes that are not directly measured, but are inferred from observations of dynamic conditions and from soil properties. Example soil qualities include natural drainage, and frost action. Soil features are attributes that are not directly part c the soil. Example soil features include slope and depth to restrictive layer. These features can greatly impact the use and management of the soil. Hydrologic Soil Group (FREEPONS VILLAGE) Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long - duration storms. The soils in the United States are assigned to four groups (A, 8, C. and D) and three dual classes (AID, BID, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. t7 167 Custom Soil Resource Report Group C. Soils having a slow Infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (AID, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. 168 18 2 N �1 a 0528205 M -2.0b zZL NAM Al _-a 2 N a ousS S 06IRZ05 091$205 KTGZ05 00I8Zos 04ORM O"ZOS At ZA, aZZL o �i 21 2 g i3 ry i irl a o oL 2� AM1 ,SL Aa d2t 2 � 2 a N 169 Q CL m (i U 7 VJ a) fY D U7 Ln 170 a. d o o m O C� O w �` w .J.. ❑ m N ID a N SN6 7 2 W N V +�- Q1 .Q rLA m w ❑ v w ro f0 r 3 c Q❑ C C� M p t 2 n rA N _ C LI) a N� 3:7 lfl L- -t:!Q y CA O -le d1 0 E ui @�s m �= EIV u7 Q E cu 12 0 3 v�N ro m m tri.`' �� W LnG r Q (D0 QL � �-a d' �r7 ',� 3 en [tl 3 �d ." Sa m 2 ¢o w v hod D "' v 'CL ' E E L] N LU m m- p Q D [V O L 3 N [G < OLc� m L H y `a -0 CL -r- m Uj c n p� ui :3U fl Q 0 = E LL 0]cl)v — Vi O ❑ VQi ar .� C 3 cq CO y .g m j.V) 0 a !6 �+ �� Nwnr� wN i]> a iv in c w � . c E t y T.J 3� 22 mA do a is 3 2' $ rnv a U] vco 0,0 ❑m 03 = w ° E m CD 2 40�- m Q d {9 Do a,o �¢ a m ❑'D N = 2'C y�y �L'' N f=A ` w T2 N❑ 1 2-0 a p f!] 7 2 12-E 2 N C 61 ip a O W [G Im 7.0 Q O am. d [] N 7 _ � G N ro � d Ul p N❑ ro 4 fA A— L� •D 7 ❑ w iq Q (E m m N N W IE a ❑ (] L ❑ n cn ❑ d O p L d W ,O W a- m U C•] d z V] w c m b Q z D D❑ 0 'i OL o 0 w r 1 ■ N C 0 m W J m CL _ m m_ a ❑ 7 m C ¢ � a G � c d In `0 0 G C 0 t7l d Q ❑[� d C cri9 R L1 ❑ ❑ p J ❑ ❑ ❑ p 0!. ❑ ❑ ¢ = a a m m U U❑ a C S 3 m m U U❑ z c4 a m m �fl❑❑Ci0❑❑❑❑ o = a 00 0 ■ a w 51 Custom Soil Resource Report Table—Hydrologic Soil Group (FREEPONS VILLAGE) Hydrologic Soil Group—Summary by Map Unit—Clackamas County Area, Oregon (OR610) Map unit symbol Map unit name Rating Acres in AOI Percent of AN 713 Borges silty clay loam, 0 D to 8 percent slopes 13B Cascade silt loam, 3 to 8 C percent slopes 13C Cascade silt loam, 8 to 15'C percent stapes 92F Xerochrepts and B Haplaxeralls, very steep Totals for Area of Interest Rating Options—Hydrologic Soil Group (FREEPONS VILLAGE) Aggregation Method: Dominant Condition Component Percent Cutoff., None Specified Tie-break Rule.- Higher 17.0% 52.8% 22.4% 7.8% 100.0% 21 171 Custom Soil Resource Report Soil Deports The Soil Reports section includes various formatted tabular and narrative reports (tables) containing data for each selected soil map unit and each component of each unit. No aggregation of data has occurred as is clone in reports in the Soil Properties and Qualities and SuitabiIities and Limitations sections. The reports contain soil interpretive information as well as basic soil properties and qualities. A description of each report (table) is included. Soil Physical Properties This folder contains a collection of tabular reports that present soil physical properties. The reports (tables) include ail selected map units and components for each map unit. Soil physical properties are measured or inferred from direct observations in the field or laboratory. Examples of soil physical properties include percent clay, organic matter, saturated hydraulic conductivity, available water capacity, and bulk density. Engineering Properties (FREEPGMS VILLAGE) This table gives the engineering classifications and the range of engineering properties for the layers of each soil in the survey area. Hydrologic soil group is a group of soils having similar runoff potential under similar storm and cover conditions. The criteria for determining Hydrologic soil group is found in the National Engineering Handbook, Chapter 7 issued May 2007(http:/l directives. sc.egov.usda.govlGpenNonWebContent.aspx?content=I7757.wba). Listing HSGs by soil map unit component and not by soil series is a new concept for the engineers, fast engineering references contained lists of HSGs by soil series. Soil series are continually being defined and redefined, and the list of soil series names changes so frequently as to make the task of maintaining a single national list virtually impossible. Therefore, the criteria is now used to calculate the HSG using the component soil properties and no such national series lists will be maintained. Alf such references are obsolete and their use should be discontinued. Soil properties that influence runoff potential are those that influence the minimum rate of infiltration for a bare soil after prolonged wetting and when not frozen. These properties are depth to a seasonal high water table, saturated hydraulic conductivity after prolonged wetting, and depth to a layer with a very slow water transmission rate. Changes in soil properties caused by land management or climate changes also cause the hydrologic soil group to change. The influence of ground cover is treated independently. There are four hydrologic soil groups. A. B. C, and D, and three dual groups, A/D, B/D, and CID. in the dual groups, the first letter is for drained areas and the second letter is for undrained areas. The four hydrologic soil groups are described in the following paragraphs: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep. well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. 172 22 Custom Soil Resource Report Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material These soils have a very slow rate of water transmission. Depth to the upper and lower boundaries of each layer is indicated. Texture is given in the standard terms used by the U.S. Department of Agriculture. These terms are defined according to percentages of sand, silt, and clay in the fraction of the soil that is less than 2 millimeters in diameter. ''Loam," for example, is soil that is 7 to 27 percent clay, 28 to 50 percent silt, and less than 52 percent sand. If the content of particles coarser than sand is 15 percent or more; an appropriate modifier is added, for example, "gravelly." Classification of the soils is determined according to the Unified soil classification system (ASTM, 2005) and the system adopted by the American Association of State Highway and Transportation Officials (AASHTO, 2004). The Unified system classifies soils according to properties that affect their use as construction material. Soils are classified according to particle -size distribution of the fraction less than 3 inches in diameter and according to plasticity index, liquid limit, and organic matter content. Sandy and gravelly soils are identified as GW, GP, GM, GC, SW, SP; SM, and SC; silty and clayey soils as ML, CL, OL, MH, CH, and OH, and highly organic soils as PT. Soils exhibiting engineering properties of two groups can have a dual classification, for example, CL -ML. The AAS HTO system classifies soils according to those properties that affect roadway construction and maintenance. fn this system, the fraction of a mineral soil that is less than 3 inches in diameter is classified in one of seven groups from A-1 through A-7 on the basis of particle -size distribution, liquid limit; and plasticity index. Soils in group A-1 are coarse grained and low in content of fines (silt and clay). At the other extreme, soils in group A-7 are fine grained. Highly organic soils are classified in group A-8 on the basis of visual inspection, If laboratory data are available, the A-1. A-2, and A-7 groups are further classified as A -1-a, A -1-b, A-2-4, A-2-5, A-2-6, A-2-7, A-7-5, orA-7-6- As an additional refinement, the suitability of a soil as subgrade material can be indicated by a group index number. Group index numbers range from 0 for the best subgrade material to 20 or higher for the poorest. Rock fragments larger than 10 inches in diameter and 3 to 10 inches in diameter are indicated as a percentage of the total soil on a dry -weight basis. The percentages are estimates determined mainly by converting volume percentage in the field to weight percentage. Percentage (of sail particles) passing designated sieves is the percentage of the soil fraction less than 3 inches in diameter based on an ovendry weight. The sieves, numbers 4, 10, 40, and 200 (LISA Standard Series), have openings of 4.76, 2 00. 23 173 Custom Soil Resource Report 0A20, and 0.074 millimeters, respectively. Estimates are based on laboratory tests of soils sampled in the survey area and in nearby areas and on estimates made in the field. Liquid limit and plasticity index (Atterberg limits) indicate the plasticity characteristics of a soil. The estimates are based on test data from the survey area or from nearby areas and on field examination References: American Association of State Highway and Transportation Officials (AAS HTO). 2004. Standard specifications for transportation materials and methods of sampling and testing_ 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard ❑2487-00. 174 24 O Q. W U] ❑ N 0 0) E N U X ' Cm o u� o %D v 7 c? N o C w r CL cv L CL CL CL Z Z Z. 2 Z Z � r tr _ v n J M +t7 0 N N cv N N N d n m m m m no0 rn l rn m E rV +n o o o o Ln co rn r- m co t• m co o a o I o o a y i to N pp a O O a 0 O O - - to oh _ Q co o a i I V R 4 d 4 O o n CL p��l� LA o m m 175 iq C'+Y C � E C O n O O O O O 0 h - Li A Wd 4 C •- C O O CIO O O P 10 O o v=i Q ¢ 4 a Ia ¢ ¢ ¢ a a a L) ^2 (7 T y T I.] 7+ 7+ ]•• T E m ❑ Ll E d y [_T6 iYTII O vim, E m E roE roE E E E U ❑ o m aro as o mEl mE oro ❑ T _T m❑ Y o � a �. z v .. o co Fn Q w U7 U) u1 t1} SI] Q1 00 6 0. o CL U_ 7 0O °' Cf - v a .. ! no co D 'E u C roivU T y p m m a w m n H a l6 N W '8OO ' u t2 H= 0 3 QS O 4i 6 N aQ V1 V .2 in m N 'D V Q ro Nip a (� m I to ❑ O m H 0 m � it _Q [� N ou Y [4 _❑ M O y G VF U r - 175 iq C'+Y AW 176 « m LO Of E G a § § a 7 Im I¥ 0 0 c § IN N cn m 3 LO C? 2 g E 94 .G U S m , 2 N _ ��§ -r. SCD . ; 2 '02 2 § �\ /;\ a / § / CL 0 Ln $ CD LO LO m 0 -- -n . - 7 S 'p C. �$ k co ƒ CD 0 ■ \ /�/ .o.o k c \ ; ` 0 0 0 0 ■ to 9 E i & k < § J �< ED '< ƒ t £ . . . . % k A .d 3�$� 5d \'�'�k 0IL � } � cu /§� CD ] (// 5 « ��_» 3 «§2 2 �E ƒ7� fE ® EE �22g \ 3 > 7 J ` § 9 0 < $ a � • � a � - ��J oma_ 2 . .j. . IL k C ± EEva �w ) 2eGCL2 '� ©§a/ e �3e 2 �f2 / T « m References American Association of State Highway and Transportation Officials (AASHTO). 2004_ Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes, ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep -water habitats of the United States. U.S. Fish and Wildlife Service FWSIOBS-79131 _ Federal Register. July 13, 1994. Changes in hydric soils of the United States Federal Register, September 18, 2042. Hydric soils of the United States. Hurt, G.W., and L. M. Vasi las, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http-,//www.nrcs.usda-gov/wps/portal/nrcs/ detail/national/soils/?cid=nres t 42p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Depa rtment of Agricultu re Handbook 436. httpJ/www.nres.usda.gov/wps/portal/ nresldetail/nationailsoils/?cid=nres142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http://www.nres.usda.gov/wps/ portalin res/detaillnational/soils/?cid=n res142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual, Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nres.usda.gov/wpslportal/nres/detail/sods/ home/?cid=nresl42p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nres.usda.gov/wpsYportallnres/ deta il/national/landuse/rangepasture/?cid=steip rdb1043084 27 177 Custom Soil Resource Report United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 43041. http:/iwww.nrcs-usda.gov/wps/portal/ nresldeta illsoil slscie nti stsl?cid=nres 142 p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http: //www. nres. usda. gov/wpslporta I/n resld eta ii/na tional/soil sl? cid=nres142p2_a53624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www. nrcs.usda.gov/lnternet/FSE—DOCUMENTS/nrcsl 42p2_052290. pdf 178 28 a x U 179 Table C-2 RUNOFF CURVE NUMBERS Runoff curve numbers for urban areas* Cover description Curve numbers For hydrologic soil group Average percent Cover type and h drolo ric condition impervious area A B C D Open space (lawns, parts, golf courses, cemeteries, etc.): Poor condition (grass cover X50%) 68 79 86 89 Fair condition (grass cover 50% to 75°/,) 49 69 79 84 Good condition (grass cover> 75%) 39 61 74 80 Impervious areas: Paved parking lots, roofs, driveways, etc, (excluding right- 98 98 98 98 of -way) Streets and roads: Pavcd; curbs and storm sewers (excluding right-of-way) 98 98 98 98 Paved; open ditches (including right-of-way) 83 89 92 93 Gravel (including right-of-way) 76 85 89 91 Dirt (including right-of-way) 72 82 87 89 Urban districts: Commercial and business 85 89 92 94 95 Industrial 72 81 88 91 93 Residential districts by average lot size: 118 acre or less (town houses) 65 77 85 90 92 114 acre 38 61 75 83 87 113 acre 30 57 72 81 86 112 acre 25 54 70 80 85 l acre 20 51 68 79 84 2 acres 12 46 65 77 82 Runoff curve numbers for other agricultural lands* Cover description Curve numbers for hydrologic soil group Hydrologic Cover a condition A B C D Pasture, grassland, or range -continuous forage for grazing <501,,u ground cover or heavily grazed with no mulch Poor 68 79 86 89 50 to 75% ground cover and not heavily grazed Fair 49 69 79 84 >75% ground cover and lightly or only occasionally grazed Good 39 61 74 80 Meadow -continuous grass, protected from grazing and generally mowed for hay - 30 Sg 71 7$ Brush--weed-grass mixture with brush as the major element <50% ground cover Poor 48 67 77 83 50 to 75% ground cover Fair 35 56 70 77 X75% ground cover Good 30 48 65 73 Woods -grass combination (orchard or tree farm) Poor 57 73 82 86 Fair 43 65 76 82 Goad 32 58 72 79 Appendix CA: SBUH Method Portland 5tormwater Management Manual - August 1, 2008 180 C.1-4 Runoff curve numbers for other aarirultural lands* Hydrologic Simplified Ap2roaches condition Cover description C D Curve numbers for hydrologic soil group Hydrologic Good n/a 61 n/a n/a Roof Garden Cover t YpC condition A B C D Woods Infiltration & Flow -Through Planter Box Good ora 48 n/a n/a Pervious Pavement Forest litter, small trees, and brush are destroyed by heavy 76 85 89 n/a Trees grazing or regular burning. poor 45 66 77 83 Woods are grazed but not burned, and some forest litter 36 64 73 79 n/a - Does not apply, as design criteria for the relevant mitigation measures do not include the use of this soil type. *Soil Conservation Service, Urban Hydrologyfor Small Malersheds, Technical Release 55, pp. 2.5-2.8, June 1986, covers the soil. Fair 36 64 73 79 Woods are protected from grazing, and litter and brush Infiltration & Flow -Through Planter Box - assumed brush -weed -grass mixture with >75% ground cover and soil type B. Pervious Pavement - assumed gravel. adequatciy cover the sail. Good 34 55 74 77 Itunof[ cur�•e numbers for Simplified Approaches** Cover description Curve numbers for hydrolaRie sail Appendix CA: SBUH Method Portland Stormwater Management Manual - August 1, 2008 C.1-5 181 Hydrologic Simplified Ap2roaches condition A B C D Eco -roof Good n/a 61 n/a n/a Roof Garden Good n/a 48 n/a n/a Contained Planter Box Good n/a 48 n/a n/a Infiltration & Flow -Through Planter Box Good ora 48 n/a n/a Pervious Pavement _ 76 85 89 n/a Trees New and/or Existing Evergreen - 36 60 73 79 New and/or Existing Deciduous - 36 64 73 79 n/a - Does not apply, as design criteria for the relevant mitigation measures do not include the use of this soil type. *Soil Conservation Service, Urban Hydrologyfor Small Malersheds, Technical Release 55, pp. 2.5-2.8, June 1986, **CNs of various cover types were assigned to the Proposed Simplified Approaches with similar cover types as follows: Eco -roof - assumed grass in good condition with soil type B. Roof Garden - assumed brush -weed -grass mixture with >75% ground cover and soil type B. Contained Planter Box - assumed brush -weed -grass mixture with >75% ground cover and soil type B. Infiltration & Flow -Through Planter Box - assumed brush -weed -grass mixture with >75% ground cover and soil type B. Pervious Pavement - assumed gravel. Trees - assumed woods with fair hydrologic conditions. Note: To determine hydrologic soil type, consult local USDA Soil Conservation Service Soil Survey. Appendix CA: SBUH Method Portland Stormwater Management Manual - August 1, 2008 C.1-5 181 100 0 z W CL CL a 182 3D � W 0 ce a� W W ce F J Z U 0 Z Z U � W 0 LLMJ W Z 0 m llf� 6eoP41fic Real -World Geotechnical Solutions Investigation • Design - Construction Support July 25, 2014 Project No. 14-3393 Roger Edwards Silver Oak Custom Homes 14102 Goodall Road Oswego, OR 97034 Email: ro er,47@comcast.net CC: Jon Morse - AKS Engineering & Forestry, �onmaks-en .corn SUBJECT: GEOTECHNICAL REPORT FREEPONS VILLAGE 850 CEDAR STREET LAKE OSWEGO, OREGON This report presents the results of a geotechnical engineering study conducted by GeoPacific Engineering, Inc. (GeoPacific) for the above -referenced project. The purpose of our investigation was to evaluate subsurface conditions at the site and to provide geotechnical recommendations for site development. This geotechnical study was performed in accordance with GeoPacific Proposal No. P-4$22, dated April 25, 2014, and your subsequent authorization of our proposal and General Conditions for Geotechnical Services. SITE DESCRIPTION AND PROPOSED DEVELOPMENT The subject site is located at the western terminus of Cedar Street in Lake Oswego, Clackamas County, Oregon (Figure 1). The site is approximately 2.2 acres in size and topography is Predominantly flat to gently sloping to the north at grades of approximately 5 to 25 percent. Steeper slopes (up to approximately 65 percent grade) are present along the northern property line and along a shallow drainage in the northeastern portion of the site. One home and outbuilding are located on the property and vegetation consists primarily of short grasses, landscaping, and sparse trees. It is our understanding that the proposed development includes 8 lots for single family homes, new street, and associated underground utilities. A grading plan has not been provided for aur review; however, we anticipate maximum cuts and fills will be on the order of 5 feet or less. REGIONAL AND LOCAL GEOLOGIC SETTING The subject site lies within the Willamette Valley/Puget Sound lowland, a broad structural depression situated between the Coast Range on the west and the Cascade Range on the east. A series of discontinuous faults subdivide the Willamette Valley into a mosaic of fault -bounded, 14835 SW 72"° Avenue Portland, Oregon 97224 Tel (503) 598-8445 Fax (503) 941-9281 183 Cedar Street Subdivision Project No. 14-3393 structural blocks (Yeats et al., 1996). Uplifted structural blocks fora bedrock highlands, while down -warped structural blocks form sedimentary basins. The site is underlain by the late Quaternary aged Mast 1.6 million years) Willamette Formation, a catastrophic flood deposit associated with repeated glacial outburst flooding of the Willamette Valley (Yeats et at., 1996). The last of these outburst floods occurred about 10,009 years ago. These deposits typically consist of horizontally layered, micaceous, silt to coarse sand forming poorly-defined to distinct beds fess than 3 feet thick. (Madin, '1990). Underlying the Willamette Formation is a Pliocene to Pleistocene -aged (10,000 to 5.3 million years ago) conglomerate and sandstone that was likely deposited by Cascadian streams or an ancestral Clackamas River (Beeson et al., 1989). Madin (1990) maps this conglomerate as the Tertiary -aged (2-65 million years ago) Troutdale Formation. REGIONAL SEISMIC SETTING At least three major fault zones capable of generating damaging earthquakes are thought to exist in the vicinity of the subject site. These include the Portland Hills Fault Zone, the Gales Creek - Newberg -Mt. Angel Structural Zone, and the Cascadia Subduction Zone. Portland Hills Fault Zone The Portland Hills Fault Zone is a series of NW -trending faults that include the central Portland Hills Fault, the western Qatfield Fault, and the eastern East Bank Fault. These faults occur in a northwest -trending zone that varies in width between 3.5 and 5.0 miles. The combined three faults verticatly displace the Columbia River Basalt by 1,130 feet and appear to control thickness changes in late Pleistocene (approx. 780,090 years) sediment (Madin, 1990). The Portland Hills Fault occurs along the Willamette River at the base of the Portland Hills, and is about 3 miles northeast of the site_ The Datfield Fault occurs along the western side of the Portland Hills, and is about 1 mile northeast of the site. The Qatfield Fault is considered to be potentially seismogenic (Wong, et al., 2000). Madin and Mabey (1996) indicate the Portland Hills Fault Zone has experienced tate Quaternary (last 780,090 years) fault movement; however, movement has not been detected in the fast 20,000 years. The accuracy of the fault mapping is stated to be within 500 meters (Wong, et al., 2000). No historical seismicity is correlated with the mapped portion of the Portland Kills Fault Zone, but in 1991 a M3.5 earthquake occurred on a NW -trending shear plane located 1.3 miles east of the fault (Yelin, 1992). Although there is no definitive evidence of recent activity, the Portland Hills Fault Zone is assumed to be potentially active (Geomatrix Consultants, 1995)_ Gales Creek -Newberg -Mit. Angel Structural Zone The Gales Creek -Newberg -Mt. Angel Structural Zone is a 50 -mile -long zone of discontinuous, NW -trending faults that lies about 18.5 miles southwest of the subject site. These faults are recognized in the subsurface by vertical separation of the Columbia River Basalt and offset seismic reflectors in the overlying basin sediment (Yeats et al., 1996; Werner et al„ 1992). A geologic reconnaissance and photogeologic analysis study conducted for the Scoggins Dam site in the Tualatin Basin revealed no evidence of deformed geomorphic surfaces along the structural zone (Unruh et al., 1994). No seismicity has been recorded on the Gales Creek Fault or Newberg Fault (the fault closest to the subject site); however, these faults are considered to be potentially active because they may connect with the seismically active Mount Angel Fault and the rupture 3393-Freeparns Village GR ? 184 CaECPACIFIC ENGINEERING, INC. Cedar Street Subdivision Project No_ 14-3393. plane of the 1993 M5.6 Scotts Mills earthquake (Werner et al. 1992; Geomatrix Consultants, 1995). Cascadia Subduction Zone The Cascadia Subduction Zone is a 680 -anile -long zone of active tectonic convergence where oceanic crust of the Juan de Fuca Plate is subducting beneath the North American continent at a rate of 4 cm per year (Goldfinger et al., 1996). A growing body of geologic evidence suggests that prehistoric subduction zone earthquakes have occurred (Atwater, 1992; Carver, 1992; Peterson et al„ 1993; Geomatrix Consultants, 1995). This evidence includes: (1) buried tidal marshes recording episodic, sudden subsidence along the coast of northern California, Oregon, and Washington, (2) burial of subsided tidal marshes by tsunami wave deposits, (3) paleoliquefaction features, and (4) geodetic uplift patterns on the Oregon coast. Radiocarbon dates on buried tidal marshes indicate a recurrence interval for major subduction zone earthquakes of 250 to 650 years with the last event occurring 300 years ago (Atwater, 1992; Carver, 1992; Peterson et al., 1993: Geomatrix Consultants, 1995). The inferred seismogenic portion of the plate interface lies roughly along the Oregon coast at depths of between 20 and 40 miles. SUBSURFACE CONDITIONS Our site-specific exploration for this report was conducted on May 14, 2014. A total of 2 exploratory test pits were excavated with a backhoe to depths of 5 to 8 feet at the approximate locations indicated on Figure 2. Three hand auger borings were performed to a depth of 3.5 to 10 feet (see Figure 2), It should be noted that exploration locations were located in the field by pacing or taping distances from apparent property corners and other site features shown on the plans provided. As such, the locations of the explorations should be considered approximate. A GeoPacific geologist continuously monitored the field exploration program and logged the test pits and hand auger borings. Soils observed in the explorations were classified in general accordance with the Unified Soil Classification System. During exploration, our geologist also noted geotechnical conditions such as soil consistency, moisture and groundwater conditions. Logs of test pits and hand auger borings are attached to this report. The following report sections are based on the exploration program and summarize subsurface conditions encountered at the site. Undocumented Fill: Undocumented fill was encountered in hand auger boring HA -3 to a depth of 7 feet. The fall generally consisted of approximately 1 foot of medium dense to dense, silty GRAVEL (GM) underlain by soft to stiff clayey SILT (ML) to silty CLAY (CL) to a depth of 7 feet. Other areas of fill may be present outside our explorations -- especially in the vicinity of the existing structures and driveway. Buried Topsoil Horizon: The fill in hand auger boring HA -3 was underlain by a buried topsoil horizon. The buried topsoil horizon consisted of soft, gray, moderately organic SILT (OL -ML) that was approximately 112 foot thick and extended to a depth of 7.5 feet. Topsoil Horizon: Directly underlying the ground surface in test pits TP -3 and TP -4 and hand auger borings HA•1 and HA -2 was a topsoil horizon consisting of brown, low to moderately organic SILT (OL -ML). The topsoil horizon was loose, contained line roots, and extended to a depth of about 8 to 10 inches. 3393-Freepons Village GR Z GEOPACIFIc ENGINEERING, 1%5 Cedar Street Subdivision Project No, 14-3393 Willamette Formation: Underlying the topsoil horizon in test pit TP -3 was clayey SILT (ML) belonging to the Willamette Formation. The light grown silt was generally characterized by a stiff to very stiff consistency with strong orange and gray mottling. The loess extended to a depth of 2.5 feet in test pit TP -3 - Residual Soil: Underlying the topsoil horizon in test pit TP -3 and hand auger borings HA -1 and HA -2, the Willamette Formation in test pit TP -3, and the buried topsoil horizon in hand auger boring HA -3 was residual soil derived from in place decomposition of the underlying unnamed conglomerate. The light brawn silty CLAY (CL) to clayey SILT (ML) was generally characterized by a stiff to very stiff consistency with strong orange and gray mottling. The residual sail material extended beyond the maximum depth of exploration in test pits and hand auger borings (10 feet). Soil Moisture and Groundwater On May 14, 2014, groundwater seepage was encountered in test pit TP -4 at depths of 3 and 5 feet below the ground surface. Discharge was visually estimated at less than '/2 gallon per minute. Experience has shown that temporary storm related perched groundwater within the near surface soils often occur over fine-grained native deposits such as those beneath the site during the wet season and particularly in mottled soils such as were identified in the test pits. It is anticipated that groundwater conditions will vary depending on the season, local subsurface conditions, changes in site utilization, and other factors. INFILTRATION TESTING The pushed pipe method of infiltration testing was performed in test pits TP -3 and TP -4. The open -hole method was used in hand auger borings HA -1 and HA -2. The soil in the test pits and hand auger borings were pre -saturated for a period of 2 hours prior to conducting the testing. The water level was measured to the nearest tenth of an inch every twenty to thirty minutes with reference to the ground surface. Table 1 presents the results of our falling head infiltration tests. Table 1. Summary of Infiltration Test Results Exploration Depth Infiltration Hydraulic Designation (feet) Soil Type Rate(inlhr) Head Range inches TP -3 3 Clayey SILT (ML) or silty 1.9 12-17 5 2.6 12-18 CLAY (CL) trace sand TP -4 8 Clayey SILT (ML) or silty 01 23-24 CLAY CL HA -1 5 Clayey SILT (ML) or silty 0,6 9-11 CLAY(CL) HA -2 3,5 Clayey SILT (ML) or silty 1.9 20-25 CLAY CL 186 3393-Freepons Village GR 4 GEGPACIFIc ENGINEERING, INC. Cedar Street Subdivision Project No. 14-3393 SLOPE STABILITY For the purpose of evaluating slope stability; we: (1) reviewed published geologic mapping and LIAR imagery, (2) performed field reconnaissance, and (3) explored subsurface conditions in two exploratory test pits with a small trackhoe and performed three hand auger borings. Explorations indicate the site is underlain by medium stiff to very stiff residual soil that is considered highly resistant to slope instability in areas of gently sloping topography and moderately resistant in areas of moderately to steeply sloping topography. The DOGAMI online landslide database (DOGAMI, 2014) and published geologic mapping indicates no mapped landslides area present at the site or adjacent properties (Beeson et al., 1989, Madiin, 1990). A conceated fault is mapped by Beeson et al (1989) that bisects the site as indicated on Figure 1A. 0 u review of Iidar imagery (DQGAM1, 2014) indicates arcuate topography along the northern property line that may be a possible old landslide scarp, related to the concealed fault, or an erosional feature from the Missoula Floods (see Figures 1A and 1 B). Relative dynamic slope instability mapping by Mabey et al. (1995) indicates the majority of the site characterized as "having slope instability only in unusual localized conditions" with the northern slope characterized as having a low slope instability hazard. The site is characterized as having a moderate relative earthquake hazard (Zone B) where Zone A is the greatest hazard and Zone ❑ is the least hazard (Mabey et al., 1995). The majority of the subject site is gently to moderately sloping to the north Inclining at grades of 5 to 20 percent. Grades steepen to the north, north of the existing driveway, where grades average 55 to 65 percent. The northern slope has been oversteepened by the placement of fill at the top of the slope (7 feet as encountered in hand auger boring HA -3) and at the toe with the placement of a gabion wail (Figure 3), An incised drainage with steeply sloping grades is present in the eastern portion of the property. This area will remain undeveloped due to a resource protection buffer. To decrease the slope instability hazard, we recommend the fill at the top of the slope be removed to native, stiff soils and that storm related runoff is collected and disposed of off-site (see Figure 3). CONCLUSIONS AND RECOMMENDATIONS Our investigation indicates that the proposed development is geotechnically feasible, provided that the recommendations of this report are incorporated into the design and sufficient geotechnical monitoring is incorporated into the construction phases of the project. In our opinion, the greatest geotechnical issues for project completion are the potential for perched groundwater conditions and the steep slope at the north end of the site. The northern slope has been oversteepened by the placement of fill at the top of the slope (7 feet as encountered in hand auger boring HA -3) and at the toe with the placement of a gabion wall. To decrease the slope instability hazard, we recommend the fill at the top of the slope be removed to native, stiff soils and that storm related runoff is collected and disposed of off-site (see Figure 3). We do not recommend the use of open detention or stormwater infiltration facilities due to the potential for adverse impacts to slope stability. Site Preparation Areas of proposed buildings, new streets, and areas to receive engineered fill should be cleared of vegetation and any organic and inorganic debris. if encountered, existing buried structures should be demolished and any cavities structurally backfilled with engineered Fill as 3393-Freepons Village GR GEOPACIFIC ENGINEERING. I4�7 Cedar Street Subdivision Project No. 14-3393 recommended in this report. inorganic debris and organic materials from clearing should be removed from the site. Existing fill, buried topsoil horizons, and any organic -rich topsoil should then be stripped from construction areas of the site or where engineered fill is to be placed. Fill was encountered in hand auger boring HA -3 to a depth of 7 feet. Topography indicates fill has been placed along the top of the northern slope. This fill should be removed. The estimated depth range necessary for removal of topsoil is approximately 6 to 9 inches. The final depth of soil removal will be determined on the basis of a site inspection after the stripping/ excavation has been performed. Stripped topsoil should preferably be removed from the site. Any remaining topsoil should be stockpiled only in designated areas and stripping operations should be observed and documented by the geotechnical engineer or his representative. Any remaining undocumented fills and subsurface structures (tile drains, basements, driveway and Landscaping fill, old utility lines, septic leach fields, etc.) should be removed and the excavations backfilled with engineered fill_ Once stripping of a particular area is approved, the area must be ripped or tilled to a depth of 12 inches, moisture conditioned, root -picked, and compacted in-place prior to the placement of engineered fill or crushed aggregate base for pavement. Exposed subgrade soils should be evaluated by the geotechnical engineer. For Large areas, this evaluation is normally performed by proof -rolling the exposed subgrade with a fully loaded scraper or dump truck. For smaller areas where access is restricted, the subgrade should be evaluated by probing the soil with a steel probe. Soft/loose soils identified during subgrade preparation should be compacted to a firm and unyielding condition, over -excavated and replaced with engineered fill (as described below), or stabilized with rock prior to placement of engineered fill. The depth of overexcavation, if required, should be evaluated by the geotechnical engineer at the time of construction. Engineered Fill All grading for the proposed development should be performed as engineered grading in accordance with the applicable building code at time of construction with the exceptions and additions noted herein. Proper test frequency and earthwork documentation usually requires daily observation and testing during stripping, rough grading, and placement of engineered fill. Imported fill material must be approved by the geotechnical engineer prior to being imported to the site. Oversize material greater than 6 inches in size should not be used within 3 feet of foundation footings, and material greater than 12 inches in diameter should not be used in engineered fill. Engineered fill should be compacted in horizontal lifts not exceeding 8 inches using standard compaction equipment. We recommend that engineered fill be compacted to at least 90% of the maximum dry density determined by ASTM D1557 (Modified Proctor) or equivalent. Field density testing should conform to ASTM D2922 and 03017, or 11555. All engineered fill should be observed and tested by the project geotechnical engineer or his representative. Typically, one density test is performed for at least every 2 vertical feet of fill placed or every 500 yd', whichever requires more testing. Because testing is performed on an on-call basis, we recommend that the earthwork contractor be held contractually responsible for test scheduling and frequency. 188 3393-Freepons Village GR GEOPACIFlc ENGINEERING, INC, Cedar Street Subdivision Project No. 14-3393 Site earthwork will be impacted by soil moisture and shallow groundwater Conditions. Earthwork in wet weather would likely require extensive use of cement or lime treatment, or other special measures, at considerable additional cost compared to earthwork performed under dry -weather cond+tions. Excavating Conditions and Qtility Trenches We anticipate that on-site soils can be excavated to a depth of 8 feet using conventional heavy equipment such as scrapers and trackhoes. All temporary cuts in excess of 4 feet in height should be sloped in accordance with U.S. Occupational Safety and Heath Administration (OSHA) regulations (29 CFR Part 1926), or be shored, The existing native soils classify as Type B Soil and temporary excavation side slope inclinations as steep as 1 H: 1 V may be assumed for planning purposes. This cut slope inclination is applicable to excavations above the water table only. Maintenance of safe working conditions, including temporary excavation stability, is the responsibility of the contractor. Actual slope inclinations at the time of construction should be determined based on safety requirements and actual soil and groundwater conditions. Saturated soils and groundwater may be encountered in utility trenches, particularly during the wet season. We anticipate that dewatering Systems consisting of ditches, sumps and pumps would be adequate for control of perched groundwater. Regardless of the dewatering system used, it should be installed and operated such that in-place soils are prevented from being removed along with the groundwater. Vibrations created by traffic and construction equipment may cause some caving and raveling of excavation walls. In such an event, lateral support for the excavation walls should be provided by the contractor to prevent loss of ground support and possible distress to existing or previously constructed structural improvements. PVC pipe should be installed in accordance with the procedures specified in ASTM ❑2321, We recommend that trench backfill be compacted to at least 90% of the maximum dry density obtained by Modified Proctor ASTM X1557 or equivalent. Initial backfill lift thickness for a a/4"-0 crushed aggregate base may need to be as great as 4 feet to reduce the risk of flattening underlying flexible pipe. Subsequent lift thickness should not exceed 1 foot. If imported granular fill material is used, then the lifts for large vibrating plate -compaction equipment (e.g. hoe compactor attachments) may be up to 2 feet, provided that proper compaction is being achieved and each lift is tested. Use of large vibrating compaction equipment should be carefully monitored near existing structures and improvements due to the potential for vibration - induced damage. Adequate density testing should be performed during construction to verify that the recommended relative compaction is achieved. Typically, one density test is taken for every 4 vertical feet of backfill on each 200 -lineal -foot section of trench. Erosion Control Considerations During our field exploration program, we did not observe soil types that would be considered highly susceptible to erosion. In our opinion, the primary concern regarding erosion potential will occur during construction, in areas that have been stripped of vegetation. Erosion at the site during construction can be minimized by implementing the project erosion control plan, which 3393-Freepons Village GR 7GEOPACIF1c ENGINEERING, INF89 Cedar Street Subdivision Project No. 14-3393 should include judicious use of straw bales and silt fences. If used, these erosion control devices should be in place and remain in place throughout site preparation and construction. Erosion and sedimentation of exposed soils can also be minimized by quickly re -vegetating exposed areas of soil, and by staging construction such that large areas of the project site are not denuded and exposed at the same time. Areas of exposed soil requiring immediate and/or temporary protection against exposure should be covered with either mulch or erosion control netting/blankets. Areas of exposed soil requiring permanent stabilization should be seeded with an approved grass seed mixture, or hydroseeded with an approved seed -mulch -fertilizer mixture. Wet Weather Earthwork Sails underlying the site are likely to be moisture sensitive and may be difficult to handle or traverse with construction equipment during periods of wet weather. Earthwork is typically most economical when performed under dry weather conditions. Earthwork performed during the wet -weather season will probably require expensive measures such as cement treatment or imported granular material to compact fill to the recommended engineering specifications. If earthwork is to be performed or fill is to be placed in wet weather or under wet conditions when soil moisture content is difficult to control, the following recommendations should be incorporated into the contract specifications. Earthwork should be performed in small areas to minimize exposure to wet weather. Excavation or the removal of unsuitable soils should be followed promptly by the placement and compaction of clean engineered fill. The size and type of construction equipment used may have to be limited to prevent soil disturbance. Under some circumstances, it may be necessary to excavate soils with a backhoe to minimize subgrade disturbance caused by equipment traffic; • The ground surface within the construction area should be graded to promote run-off of surface water and to prevent the ponding of water,- Material ater;Material used as engineered fill should consist of clean, granular soil containing less than 5 percent fines. The fines should be non -plastic. Alternatively, cement treatment of on-site soils may be performed to facilitate wet weather placement; The ground surface within the construction area should be sealed by a smooth drum vibratory roller, or equivalent, and under no circumstances should be left uncompacted and exposed to moisture. Soils which become too wet for compaction should be removed and replaced with clean granular materials; Excavation and placement of fill should be observed by the geotechnical engineer to verify that all unsuitable materials are removed and suitable compaction and site drainage is achieved; and Bales of straw and/or geotextile silt fences should be strategically located to control erosion. If cement or lime treatment is used to facilitate wet weather construction, GeoPacific should be contacted to provide additional recommendations and field monitoring. 190 3393-Freepons Village GR GEOPACIFIc ENGINEERING, INC. Cedar Street Subdivision Project No. 14-3393 Anticipated (Foundations The proposed residential structures may be supported on shallow foundations bearing on competent undisturbed, native soils and/or engineered fill, appropriately designed and constructed as recommended in this report_ Foundation design, construction, and setback requirements should conform to the applicable building code at the time of construction. For maximization of bearing strength and protection against frost heave, spread footings should be embedded at a minimum depth of 18 inches below exterior grade. The recommended minimum widths for continuous footings supporting wood -framed walls without masonry are 12 inches for single -story, 15 inches for two-story, and 18 inches for three-story structures. Minimum foundation reinforcement should consist of a No. 4 bar at the tap of stem walls, and a No. 4 bar at the bottom of footings. The anticipated allowable soil bearing pressure is 1,500 lbs/ft` for footings bearing on competent, native soil and/or engineered fill. A maximum chimney and column load of 30 kips is recommended for the site. The recommended maximum allowable bearing pressure may be Increased by 1/3 for short-term transient conditions such as wind and seismic loading. For heavier loads, the geotechnical engineer should be consulted. The coefficient of friction between on-site soil and poured -in-place concrete may be taken as 0.45, which includes no factor of safety. The maximum anticipated total and differential footing movements (generally from soil expansion and/or settlement) are 1 inch and 1/4 inch over a span of 20 feet, respectively. We anticipate that the majority of the estimated settlement will occur during construction, as loads are applied. Excavations near structural footings should not extend within a 1 H:1 V plane projected downward from the bottom edge of footings. Footing excavations should penetrate through topsoil and any loose soil to competent subgrade that is suitable for bearing support. All footing excavations should be trimmed neat, and all loose or softened sol! should be removed from the excavation bottom prior to placing reinforcing steel bars. Due to the moisture sensitivity of on-site native soils, foundations constructed during the wet weather season may require overexcavation of footings and backfill with compacted, crushed aggregate. Our recommendations are for house construction incorporating raised wood floors and conventional spread footing foundations. If living space of the structures will incorporate basements, a geotechnical engineer should be consulted to make additional recommendations for retaining walls, water -proofing, undersiab drainage and wall subdrains. After site development, a Final Soil Engineer's Report should either confirm or modify the above recommendations. Drainage The outside edge of uphill perimeter footings may be provided with a drainage system consisting of 3 -inch diameter, slotted, plastic pipe embedded in a minimum of 1 W per lineal foot of clean, free -draining gravel or 314" — 0 rock. Water collected from the footing drains should be directed into the local storm drain system or other suitable outlet. A minimum 0.5 percent fall should be maintained throughout the drain and non -perforated pipe outlet. Down spouts and roof drains should not be connected to the foundation drains in order to reduce the potential for clogging. The footing drains should include clean -outs to allow periodic maintenance and inspection. Grades around the proposed structure should be sloped such that surface water drains away from the building. An adequate grade to a low point outlet drain in the crawlspace is required by code. 3393-Freepons Village GR L� GEOPACIFIc ENGINEERING, iN 9J Cedar Street Subdivision Project No. 14-3393 Seismic Design Structures should he designed to resist earthquake loading in accordance with the methodology described in the 2006 International Residential Code {IRC} for ane- and Two -Family Dwellings, with applicable Oregon Structural Specialty Code (OSSC) revisions. We recommend Site Class D be used for design per the OSSC, Table 1613.5.2. Design values determined for the site using the USGS (United States Geological Survey) Earthquake Ground Motion Parameters utility are summarized in Table 2 — presented on the following page. Table 2 - Recommended Earthquake Ground Motion Parameters (2006 IRC) Parameter Value f Location (Lat, Long), degrees 45.406, -122.670 _ Mapped Spectral Acceleration Values MCE : Short Period, SS 0.95 1.0 Sec Period, S, 0.34 Soil Factors for Site Class D - Fa 1.12 F„ 1.73 Residential Site Value = 213 x F,, x S,, 0.71 I Residential Seismic Des ig n Cate ory D, Soil liquefaction is a phenomenon wherein saturated soil deposits temporarily lose strength and behave as a liquid in response to earthquake shaking. Soli liquefaction is generally limited to loose, granular soils located below the water table. Following development, on-site soils will consist predominantly of engineered fill, native fine-grained soils, or basalt bedrock, which are not considered susceptibte to liquefaction. Therefore, it is our opinion that special design or construction measures are not required to mitigate the effects of liquefaction 192 3393-Freepons Village GR I [1 GEoPAC«rc ENGINEERING, INC. Cedar Street Subdivision Project No. 14-3393 UNCERTAINTIES AND LIMITATIONS We have prepared this report for the owner and their consultants for use in design of this project only. This report should be provided in its entirety to prospective contractors for bidding and estimating purposes; however, the conclusions and interpretations presented in this report should not be construed as a warranty of the subsurface conditions. Experience has shown that soil and groundwater conditions can vary significantly over small distances. Inconsistent conditions can occur between explorations that may not be detected by a geotechnical study. If, during future site operations, subsurface conditions are encountered which vary appreciably from those described herein, GeoPacific should be notified for review of the recommendations of this report, and revision of such if necessary. Sufficient geotechnical monitoring, testing and consultation should be provided during construction to confirm that the conditions encountered are consistent with those indicated by explorations. The checklist attached to this report outlines recommended geotechnical observations and testing for the project. Recommendations for design changes will be provided should conditions revealed during construction differ from those anticipated, and to verify that the geotechnical aspects of construction comply with the contract pians and specifications. Within the limitations of scope, schedule and budget, GeoPacific attempted to execute these services in accordance with generally accepted professional principles and practices in the fields of geotechnical engineering and engineering geology at the time the report was prepared. No warranty, expressed or implied, is made. The scope of our work did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous or toxic substances in the soil, surface water, or groundwater at this site. We appreciate this opportunity to be of service. Sincerely, GEGPACIFIc ENGINEERING, INC. (,-v Iq- - Beth K. Rapp, R.G. Senior Geologist EXPIRES: 06/30/20 IS James D. Imbrie, P,E., G.E. Principal Geotechnical Engineer Attachments: References Figure 1A — Vicinity Map Figure 18 — LIDAR Map Figure 2 — Site and Exploration Plan Test Pit Logs (TP -3 and TP -4) Hand Auger Logs (HA -1 through HA -3) 3393-Freepons Village GR I 1 GEoPACIFIc ENGINEERING, tNF93 Cedar Street Subdivision Project No. 14-3393 REFERENCES Atwater, 8.F., 1992, Geotogic evidence for earthquakes during the past 2,000 years along the Copalis River. southern coastal Washington: Journal of Geophysical Research, v. 97, p, 1901-1919. Beeson, M. H., Tolan, T. L., and Madin, f.P., 1989, Geologic map of the Lake Oswego quadrangle, Clackamas: Multnomah, and Washington Counties, Oregon Oregon Department of Geology and Mineral industries Geological Map Series GMS -59, scale 1:24,000. Carver, G.A., 1992, Late Cenozoic tectonics of coastal northern California. American Association of Petroleum Geologists-SEPM Field Trip Guidebook, May, 1992. Geomatrix Consultants, 1995, Seismic Design Mapping, State of Oregon: unpublished report prepared for Oregon Department of Transportation, Personal Services Contract 11688, January 1995. Goldfinger, C., Kuim, L.D., Yeats, R.S., Appelgate, B. MacKay, M.E., and Cochrane, G.R., 1996, Active strike - slip faulting and folding of the Cascadia Subduction-Zone plate boundary and forearc in centfal and northern Oregon: in Assessing earthquake hazards and reducing risk in the Pacific Northwest, v. 1 U.S. Geological Survey Professional Paper 1550, P. 223-256. Madin, ;.P., 1990, Earthquake hazard geology maps of the Portland metropolitan area. Oregon: Oregon Department of Geology and Mineral Industries Open -File Report 0-90-2, scale 1:24,000, 22 p. Mabey, M.A., Madin, I.P., and Meier, D.$., 1995, Relative earthquake map of the Lake Oswego Quadrangle, Clackamas and Multnomah Counties, Oregon; Oregon Department of Geology and Mineral Industries, GMS -91, 6 pages, scale 1:24,000, Oregon Department of Geology and Mineral Industries, 2014, Statewide Landslide Information Database for Oregon (SLIDO): hitp://www.oregoncLQoloqy.orc;Islido/index-htmi Peterson, C.D., Danoenzo, M.E.. Burns, S.F., and Burris. W.K., 1993, Field trip guide to Cascadia paleoseismic evidence along the northern California coast: evidence of subduction zone seismicity in the central Cascadia margin: Oregon Geology, v. 55, p. 99-144. Unruh, J, R., Wang, I.G., Bott, J.D., Silva, W.J., and Lettis, W.R., 1994, Seismotectonic evaluation: Scog gins Dam, Tualatin Project, Northwest Oregon: unpublished report by William Lettis and Associates and Woodward Clyde Federal Services, Oakland, CA, for U. S. Bureau of Reclamation, Denver CO (in Geomatrix Consultants, 1995), Werner, K.S., Nabelek, J., Yeats, R.S., Malone, S.. 1992, The Mount Angel fault: implications of seismic - reflection data and the Woodburn, Oregon, earthquake sequence of August, -1990: Oregon Geology, v. 54, p. 112-117. Wong, I. Silva, W., Bott, J., Wright, D., Thomas, P_, Gregor; N., Li., S., Mabey, M„ Sojourner, A., and Wang, Y„ 2000, Earthquake Scenario and Probabilistic Ground Shaking Maps for the Portland. Oregon, Metropolitan Area, State of Oregon Department of Geology and Mineral Industries; Interpretative Map Series IMS -15. Yeats, R.S., Graven, E.P., Werner, K.S.. Goldfinger, C., and Popowski, T., 1996, Tectonics of the Willamette Valley, Oregon: in Assessing earthquake hazards and reducing risk in the Pacific Northwest. v. 1: U.S. Geological Survey Professional Paper 1560, P. 183-222, 5 plates, scale 1.100,000. Yelin, T.S., 1992, An earthquake swarm in the north Portland Hills (Oregon): More speculations on the seismotectonics of the Portland Basin: Geological Society of America, Programs with Abstracts, v. 24, no. 5, P. 92. 194 3393-Freepons Village GR 1 ? GEOPACIFlc ENGINEERING, INC. 14835 SW 72nd Avenue Gaup cifi� Portland, Oregon 97224 VICINITY MAP lgff r rl Tel: (583) 598-8445 Fax: (503) 941.9281 lei f.,'��.er r� •: •rte �' 't�► • ' � ' '�. ; r r•., .. I � r��ad.. �y'' ii ev �. y •r. • - . f �'` ori • } v r': 4f lff.: Ci •'Is ..tt't, Ft'17• �1 •'yl.,� .. ,r k'y r� + 'r`j�rC• f.l�M.i:i ! ,f, 44 It l.a 1Natru• al, ' �.,31ydyt .r}: l 1 W�larLadd � r IK � �17 � � �i, • , ,+ � a J 71 � ,, a +`ti ,"ir'• ;.1 r', ', i f: ,+" i1 'f '� 'E Tgsd I.l,.ri,uRtt' Too- 5,•1' 7'IS i•i , "}`-Y+ 'f ;I: .1�F�1 1'�j1 S : TgWvy Sy 3+ .Tgwwrdi•:Y, • _ _ it +l�n:riti.�• h �r •r' ti' tl,', ' ' •--_L-' • _. .. •Ei• /• WR .r ;.. •,aSr F[ Ff}ab _�I--.r•y„^�� ^�, M+rr, 't rl• .'.�'• ; �± `'} yaw j SUBJECT SITE �- �'�`� ":r �i F�! '� II -1. .w•/ .Qlig TE t vE i a . ��< •:1V I' t I t }} �.r r3 �t' S iYgab ray Qrf =.-'` • n� 1 t T+fah ;'Ph.E. ^lid .e ri C:r , •, t',i#xruluue - YAC .: _ .•�j�l�Iri'- �•.�y�?..:Y i ....r. H44.rlei r f Y is r,YJ "e•_ r L :R�' t •.. ifr:;,. ,. r tpy� ,IR- ti T!q � �•+�1 t a. w' `.. , r,�� r �� relnnsf :71i ifri, �' ,R.. . 1 •(8000 dem ! ii i ` ��_ :yen txf:rllYri::d' 9 u ".�� 1'fsr1. r � � �� f � '� •l- ^.� Irl�rn� :ti' ;.c,i:„�'.tii� Iga� �..atl. Trbr, i �. �:.'x NORTH Tgbb 1 j, rT1g Tgww T Ttg 1 t rr v :'i{ug::. J7. t VM1 "f - /' :l I u l• i It =: Date: 7/2512014 Legend Approximate Scale 1 in = 2.000 ft Drawn by: EKR Base map: Beeson, MAL, Tolan• T.L., and Madin, I.P„ 1889• Geologic map of the Lake Oswego Quadrangle, Clackamas. Multnomah, and Washington Counties, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS -59, scale 1:24,000. Project: Freepons Village Project No. 14-3393 FIGURE 1A Lake Oswego, Oregon 195 14835 SW 72nd Avenue Geopiewc Portland, Oregon 97224 VICINITY MAP Tel; (503) 598-8445 Fax: (503) 941-9281 r v' •��+ •� /Y ""ter �.. + ...,+ - '• SUBJECT SITE ' ' ,�' t ,,. �R y _ � • it tI ... , " •�~ •�„1 t •14' Hi h Resolution digital elcvation ma; Dogami, 2p14j ► ' # y !' •- i � 9e r �}: SUBJECT SITE r� } MAPPED LANDSLIDES o..h High resolution digital elevation map with map ed landslides of 1••�. Project: Freepons Village Project No. 14-3428 FIGURE 1 B Lake Oswego, Oregon 196 _0 -4 r C7 ❑��CD � 0 � .e y fD Qr- n r- CD p= L<• = -goo oEn � y N — 1 •,. i`>.�p �a rcc 3��t rr �Fl! RyT+ `y ,r` r i. CID (D O (a ❑s~In In co CA � Q1 � a r:•+� • cr :x r+ i1 *1 W Q is ❑01 � , - - - ,� .✓',� - i tl . � 5 � I '�rfx _ m x Q 7 7 tir( ter,.. 3 r ^. N toal to a V - N C o N �. CCD CLA o _ CL 14 w z n C v 37 -0-0(0�g h] a m 133"2 co f x N x C0 W p '.- r �'� rf? N� 4 �• tr s x 5 6] gyp• -- — .`�•" �` � � - -' .'.ti J � �'1 5r� i � € .. rte+• lil i- i .' i • • ':1 ❑ I i LCp}. � �+ Q > / 5 525 _ u !P'•.. tx U)u nq r r , " ' iF I m r& x s ❑ 1 _ CID ld rA4U3 IL. CL �m M C�s �'g x m TAX .:OT•I�zor �r I1 d _ --_0 Z N > Q m m a ______� CA 0 ? 0 197 14835 SW 72nd Avenue 6910'(P4iffe Portland, Oregon 97224 Rim. 1-111.MmM Tel: (503) 598-8445 Fax: (503) 941-9281 C) o 0 n W W Qt] N N r I 1 PROPERTY LINE --- GABION WALL —310 HA -3 (PROJECTED) RETAINING WALL + 1 1 1 1 1 f 1 r 1 r r Z r 0 1 N WI Q J W ❑ i !r a 1 ❑ 1 � TP -3 :bo 0 o a It N a N N N I I {X 11 O w I. J .W .I ❑ �I U— z � :n w r aaz i� Q d 0 z H W U) a 0 sL GEOLOGIC SECTION 0 co 0 Z L D i Q LU C C < C � C J _ U w . > c ❑ L Z - I LL I � I I! I z I I I w I LLJ Q WU I W u7 I FW - I Z 2 D I I Q 0 PROPERTY LINE I w W = J 0. W ¢ O 00 W It (V 0 Gd (0 r] N N IN N N Project: Freepons Village Project No. 14-3393 Date: 7/25/2014 FIGURE 3 Lake Oswego, Oregon Drawn by: EKR 198 14835 SW 72nd Avenue CeoP�ifiC Portland, Oregon 97224 TEST PIT LOG Tel: (503) 598-8445 Fax: (503) 941-9281 Project: Freepons Village Project No. 14-3393 Test Pit No. TP- 3 Lake Oswego, Oregon -- °' �° °' a 0- _�' a Material Deszri tion P E ❑ [] a N m Low to moderately organic SILT (CL -ML), brown, fine roots throughout, loose, moist (Topsoil) 1 — 1.5 ------------� ----------------------------- Stiff to very stiff, clayey SILT (ML), light brown, micaceous, trace fine roots, strong orange and gray mottling, trace black staining, moist {Loess} 2 2.5 3 - 4.5 ----------------------------------------- Stiff to very stiff, clayey SILT (ML) to silty CLAY (CL), trace sand, light brown, micaceous, partially cemented, subtle orange and gray mottling, trace black 4- 4.5 staining, moist (Residual Soil) 5— Test Pit Terminated at 5 Feet for Infiltration Testing. 5 Note: No seepage or groundwater encountered. 7 8 9- 10 11- 12 LEGEND a Date Excavated: 5/14/2014 77 Logged By: B. Rapp 1900 ` • 77 Surface Elevation: Beg Sample Bucker Sample Shelby Tube Sample Seepage water Bearing Zone Vueler Level at Abanden"m JJ 200 14835 SW 72nd Avenue G®DPC portland, Oregon 97224 TEST PIT LOG , Tel: (503) 598-8445 Fax: (503) 941-9281 Project: Freepons Village Project No. 14-3393 Test Pit No. TP -4 Lake Oswego, Oregon Y Ei� -N^ �m 67e m ❑ yN no20 a. n NOS �. .Ntl1 me .� Material Description 0 m v o a cn m Low to moderately organic SILT (OL -ML), brown, fine roots throughout, loose, moist (Topsoil) 1- 2.5 --------------------------------------- 2 - 2.0 3- 2.0 Stiff to very stiff, clayey SILT (ML) to silty CLAY (CL), trace sand, light brown, micaceous, partially cemented, subtle orange and gray mottling, trace black 4 2.0 staining, moist (Residuat Soil) 5- -5- 6- 7- 7-8 8 - Test Pit Terminated at 8 Feet for Infiltration Testing. 9 - Note: Groundwater seepage encountered at 3 and 5 feet. 10-- Discharge visually estimated at fess than 1/2 gallon per minute. 11- 12 LEGEND Date Excavated: 5/14/2014 1 pd CG 11C{fAl Logged By: B. Rapp 77 Surface Elevation: Bag Sample Bucket Sample Shelby Tube Sample seepage Water Bearing Zone Waler Level at Abandonmem PMC14835 72nd Avenue Portland, Oregon 97224 G , HAND AUGER LOG Tel: (503) 598-8445 Fax: (503) 941-9281 Project: Freepons Village Lake Oswego, Oregon Project No. 14-3393 Hand Auger No. HA -1 -X E 'y 0 (13C 0 p '2 0 a Q Q C N o C Material Description o 0 U a U) Co Moderately organic SILT (OL -ML), brown, fine roots throughout, loose, moist (Topsoil) ----------------------------------------- 2- Stiff to very stiff, clayey SILT (ML) to silty CLAY (CL), trace sand, light brown, micaceous, strong to subtle orange and gray mottling, trace black staining, moist (Residua! Soil) 3- 4 5 -- Hand Auger Boring Terminated at 5 Feet for Infiltration Testing. 6 -- Note: No seepage or groundwater encountered. 7 8- 9 10- 11- 12 - LEGEND Date Excavated: 5/14/2014 t.000 7 Logged By: B. Rapp Bag Sample Bucket Sample Shelby Tube Sample Seepage Water Bearing Zone Water Level at Abandonmenl Surface Elevation: w I 202 14835 SW 72nd Avenue G®vPiff(; Portland, Oregon 97224 HAND AUGER LOG Tel: (543) 598-8445 Fax: (503) 941-9281 Project: Freepons Village Lake Oswego, Oregon Project No. 14-3393 an9 Hand Auger No. HA -2 m am Y vs 34 0 © a 5 2 CL0� Vg °' °'.6 a0.6 �" oH z g o � Material Description ❑ U Moderately organic SILT (OL -ML), brown, fine roots throughout, loose, moist (Topsoil) 1 — --------------------------------------- Medium stiff to very stiff, clayey SILT (ML) to silty CLAY (CL), trace sand, light 2— brown, micaceous, strong orange and gray mottling, trace black staining, moist (Residual Soil) 3— 4 Hand Auger Boring Terminated at 3.5 Feet for Infiltration Testing, 5 Note: No seepage or groundwater encountered. 6- 7 8 9- 10 11- 12 LEGEND Date Excavated: 5/14/2014 1,00 5t 5"`'� ® Logged By: B. Rapp Surface Elevation: Bag Sample Bucket Sample Shelby Tube Sample Seepage Water Bearing Zona Water Level at Abandonment 14835 5W 72nd Avenue Genf rifir, Portland, Oregon 97224 HAND AUGER LOC Tel: (503) 598.8445 Fax: (503) 941-9284 Project: Freepons Village Lake Oswego, Oregon Project No. 14-3393 Hand Auger No. HA -3 t V O N s1 [/� (U NC i71 Ti a. y p E c P O Material Description ..- V) v a m - Medium dense to dense, silty GRAVEL (GM), gray, moist (Fill) 1 - ----------------------------------------- 2 Stiff, clayey SILT (ML) to silty CLAY (CL), light brown, strong orange and gray mottling, micaceous, moist (Fill) 3 4 ---------------------------------------- 5 _ Soft, clayey SILT (ML) to silty CLAY (CL), trace subrounded to subangular gravel, brown, trace inorganic debris, strong to subtle orange and gray mottling, 6-- trace black staining, moist (Fill) 7Moderately organic SlL7 SU -L : -K C T trace clay, gray, trace'tine roots, maisf (buried Tol soill------`-------_--T----------`-- 8- - Stiff, clayey SILT (ML) to silty CLAY (CL), trace sand, fight brown to gray, strong to subtle orange and gray mottling, trace black staining, moist (Residual Soil) 9 10 - Hand Auger Boring Terminated at 10 Feet. 11 Note: No seepage or groundwater encountered. 12 LEGEND nto � , 77 Date Excavated: 5/14/2014 Logged By: B. Rapp F. Bag Sample Bucket Sample Shelby Tube Sample Seepage Water Beanng Zane Water Level at Abandonment Surface Elevation: 74 �0-2 0 z W CL CL Q 204 z 0 a f ce 0 LLz TUALATiN VANCOUVER • SALEM 12965 SW HERMAN Ra., SUITE 100 • TUALAnN, OR 97062 M(503)56"151 F: MOM 5636152 ENGINEERING & FORF_STRY September 25, 2014 Todd Knepper City of Lake Oswego Engineering Division 380 A Avenue Lake Oswego OR, 97034 RE: Freepons Village — Subdivision {LU I4-0045) Stormwater System Downstream Analysis Dear Todd: AKS Engineering and Forestry, LLC has prepared this letter to provide information on the downstream stormwater conveyance system for development of the Freepons Village Subdivision. The project site is located at 850 Cedar Street in Lake Oswego, OR. The subject site has been separated into four onsite post developed stormwater basins (Z, XP, Y-1, Y-2). A post developed onsite basin map has been provided in Appendix 1-1. Runoff from basin Y-1 is captured and routed to the new stormwater main located within the private access lane. Stormwater runoff from basin Y-1 is routed through the onsite detention system and then to the existing storm manhole located in the Cedar Street cul-de-sac. Stormwater runoff from basin Z sheet flows to the vegetated planter box at the northwest corner of the site, and then is conveyed to the existing manhole located in the Cedar Street cul-de-sac. Basins XP and Y-2 include pervious surface area, which will not be conveyed to the public stormwater system located in Cedar Street. These areas will be largely undeveloped and will continue to drain as they currently do. In addition to onsite contributions, there are several offsite basins (totaling approximately 55 acres) that contribute stormwater runoff to the downstream conveyance system. An offsite basin delineation exhibit has been included with this letter. The pervious/impervious areas for these basins have been approximated using Table C-2 (included with this letter) of the Portland Stormwater Management Manual. The downstream conveyance system was analyzed for approximately 800 feet to an open channel discharge point at the intersection of Laurel Street and Dyer Street. The downstream conveyance system's alignment and grade was determined based on City provided as-builts, and City GIS information (see attached downstream conveyance map). At the open channel discharge point (end of analysis), the subject site's area is equivalent to less than 4% of the total upstream basin area. 205 HydroCAD computer software aided in the analysis of the downstream conveyance system. The pipe capacity was determined utilizing Manning's equation for the 25 -year (3.8 inch) storm event. The results of the HydroCAD analysis (see attached calculations) show that all downstream conveyance pipes have adequate capacity to convey runoff from the 25 -year storm event. The system is capable of passing all contributing stormwater runoff from each basin including runoff contributed from the developed project site. Based on the results of the downstream conveyance analysis, no downstream improvements are needed for the Freepons Village development. Sincerely, AKS ENGINEERING & FORESTRY, LLC Montgomery B. Hurley — PE, PLS, Principal Freepons Village Silver Oak Custom Homes 206 September 25, 2014 Page 2 3F1fllO311H3HV 3dVOSUNVI - A81S3WOd 3001 1 SZ M S,M3SSV A,JMOO SMMM M 1045 V '0049 '00£9 'ION 'OOZS S101 XV1 UNIA3Aaf1S - 'JNINNVId - C I N00380 003MSO 3)IVI W03'6w-Sj0'MMM sl�qv� 19T9STSS 9XVd N19T99TO9 3NOHd Z9OL6 8O 'NllvlVfU 001 311nS ON NVNVY183N MS 996Z1 011 'A81S3803 0NV ON103NON3 SAV 133HJLS EIV033 058 3Jd�-11n SNOd33H=l 3 J � Q 25 C W W Z Z � Z m O O z N Z Q d < m n o Q !W- O Z UZ - m O WIO U to C w N t::Z = C D CU dWl NESV a MUS -430 w w m U-) � W z o N o N") / /� /l 11 1((----�------------------- 4— ---- 4—4-1SNdNIIItiH�J cnr \\ \ °`)l \\ ,� � tib; w i�l \'✓� �\� � � \ �. 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N L.J. - -i 8 15251 • 1535 J Ot "73-1 1 ,:s T fi 1 i�s5 W t tre 1 A 208W :2J ` ti 1 Q- cn LL Lrj �� Li 1 L O *� ' it qtr46 .140 r .} CNJ a J �. Q k C, 1110 Ha M 14 1 p 1 1$ 7.1, 1111 171 1 l — -- ---� � •�^ 17451 _ �. 'y •.. � ! T7 17(� +'b S <:J 17465 r • .1r 4 11471 Q ssF+y�r�3ifty7� c.,i a-rir}r♦•♦ t.7 Jaddo 97 -J 1 i` 11'%1 L 'r+ ° N ! 1 " r tu' ` ! - � " 605 "� t 545� C r 1 (;;_c01 1G949 O 11001 CHERRI X ,s11 til.' Cl�tt`I_F , —.._'1' '(! d — 1 - ,t�, 1130 ! 114 11 j i 2 I ?fi0� !661 1 I T �W V r Q�1, J 141)1 I t0 1121 1 Z 14 X71 1 OD O 147 W LR I H 209 Table C-2 RUNOFF CURVE NUMBERS Runoff curve numbers for urban areas* Cover description Curve numbers for hydrologic soil group Average percent Cover type and hydrologic condition impervious area A B C' D Open space (lawns, parks, golf courses, cemeteries, etc.): Poor condition (grass cover X50%) 68 79 86 89 Fair condition (grass cover 50% to 75%) 49 69 79 84 Good condition (grass cover > 75%) 39 61 74 80 Impervious areas: Paved parking lots, roofs, driveways, etc. (excluding right- 98 98 98 98 of -way) Streets and roads; Paved; curbs and storm sewers (excluding right-of-way) 98 98 99 98 Paved; open ditches (including right-of-way) 83 89 92 93 Gravel (including right-of-way) 76 85 89 91 Dirt (including right-of-way) 72 82 87 89 Urban districts: Commercial and business 85 $9 92 94 95 Industrial 72 81 88 91 93 Residential districts by average lot size: 118 acre or less (town houses) 65 77 85 90 9, 114 acre 38 61 75 83 87 113 acre 30 57 72 81 86 112 acre 25 54 70 80 85 1 acre 20 51 68 79 84 2 acres 12 46 65 77 82 Runoff curve numbers for other a ricultural lands* Cover description Curve numbers for h drolo is soil grisup Hydrologic Cover type condition A B C D Pasture, grassland, or range -continuous forage for grazing <50% ground cover or heavily grazed with no mulch Poor 68 79 86 89 50 to 75% ground cover and not heavily grazed Fair 49 69 79 84 X75'%u ground cover and lightly or only occasionally grazed Good 39 61 74 $o Meadow -continuous grass, protected from grazing and generally mowed for hay 30 58 71 78 Brush--weed-grass mixture with brush as the major clement X50% ground cover Poor 48 67 77 83 54 to 75% ground cover Fair 35 56 70 77 >75% ground cover Goad 30 48 65 73 Woods -grass combination (orchard or tree farm) Poor 57 73 82 86 Fair 43 65 76 82 Good 32 58 72 79 Appendix C.1: SBUH Method Portland Stormwater Management Manual - August 1, 2008 210 C.1-4 Runoff curve numbers for other a ricultural lands* Hydrologic Simplified Approaches Cover description A B Curve numbers for hydrologic soil group Hydrologic Eco -roof Good covertype condition A B C D Woods Contained Planter Bax Good n/a 48 n1a n/a Forest litter, small trees, and brush are destroyed by heavy Good n/a 48 n/a Na Pervious Pavement grazing or regular burning. poor 45 6b 77 83 Woods are grazed but not burned, and sonic forest litter New and/or Existing Evergreen 36 60 covers the soil, F air 36 60 73 79 Woods are protected from grazing, and litter and brush *Soil Conservation Service. Urban Hydrolog),for Small Watersheds, Technical Release 55, pp. 2.5-2.8, June 1986. **CNs of various cover types were assigned to the Proposed Simplified Approaches with similar cover types as follows: adequately cover the soil. Good 30 55 74 77 Runoff curve numbers for Simplified Approaches*" Cover descrioliun Curve numbers for lA droln is soil Appendix CA: SBUH Method Portland Stormwater Management Manual - August 1, 2008 C 1-5 211 Hydrologic Simplified Approaches condition A B C D Eco -roof Good n/a 61 n/a n/a Roof Garden Good n/a 48 n/a n/a Contained Planter Bax Good n/a 48 n1a n/a Infiltration & Flow -Through Planter Box Good n/a 48 n/a Na Pervious Pavement - 76 85 89 n/a Trees New and/or Existing Evergreen 36 60 73 79 New and/or Existing Deciduous - 36 60 73 79 n/a - Does not apply, as design criteria for the relevant mitigation measures do not include the use of this soil type. *Soil Conservation Service. Urban Hydrolog),for Small Watersheds, Technical Release 55, pp. 2.5-2.8, June 1986. **CNs of various cover types were assigned to the Proposed Simplified Approaches with similar cover types as follows: Eco -roof - assumed grass in good condition with soil type B. Roof Garden - assumed brush -weed -grass mixture with X75% ground covet and soil type B. Contained Planter Box - assumed bntsh-weed-grass mixture with >75% ground cover and soil type B. Infiltration & Flaw -Through Planter Box - assumed brush -weed -grass mixture with >75% ground cover and sail type B. Pervious Pavement - assumed gravel. Trees - assumed woods with fair hydrologic conditions. Note: To determine hydrologic soil type, consult local USDA Soil Conser►•ati0n Service Soil Survey. Appendix CA: SBUH Method Portland Stormwater Management Manual - August 1, 2008 C 1-5 211 BASIN C� IX -11 TING MAIN IN CEDAR ST 0 BASIN 8 D BASIN L f - �RJ>F41� 3 R4 �• R2 XP \ _ R2 �Zii E IMPERVIOUS T DETAINED (4� 53 ONSITE PERVIOUS FLOWING OFFSITE 54 Reach an Link 212 R6 DDVMSTREAM OUTFALL R5 R5� E BASIN H V4 BASIN E V4� V3 V3 Vi �V7 Y-2 � 2 Y2 S2 ' L C� S1 BASIN P DETENTION PIPE S Y -1p Y -1p Y-11 3845 (DOWNSTREAM ANALYSIS EAST Prepared by AKS ENGINEERING Printed 10/16/2014 H droCAD@ 8.50 sln 005096 O 2007 H dreCAD Software solutions LLC Page 2 Area Listing (all nodes) Area (Sq -ft) CN Description (subcatchmen t -numbers) 5,818 70 BRASH WEED GRASS MIXTURE 50-75% (Xp) 22,700 74 BRUSH -WEED GRASS MIXTURE 50-75% (Y-2) 251,995 74 FREEPONS PARK (OPEN SPACE - GRASS COVER > 75%) (P) 31,454 74 GOOD CONDITION GRASS X75% COVER, HSG C (Y -1p) 1,850 74 GRASS GOOD CONDITION X75% COVER, HSG C (Zp) 134,992 75 ASSUME AVG .25 ACRE LOT, HSG B (E) 1.162.094 80 ASSUMES 75% PERVIOUS - AVG .5 ACRE LOT, HSG C (P) 131,900 83 ASSUME AVERAGE 25 ACRE LOT, NSG C (B,L) 107,201 83 ASSUME AVG ,25 ACRE LOT, HSG C (C) 583,138 87 ASSUME AVG .25 ACRE LOT, HSG D (H) 33,534 98 {Y-1i,Zi} 2,466,675 TOTAL AREA 213 3845 DOWNSTREAM ANALYS Type lA 24 -hr 25 -YR LAKE OSWEG❑ STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCADC18.54 sln 005095 C� 2007 HydroCAD Software Solutions LLC - Page 3 Time span=17.00-24.00 hrs, dt=0.01 hrs, 2401 points Runoff by SBUH method Reach routing by Stor-Ind+Trans method - Pond routing by Star -Ind method SubcatchmentB: BASIN B Runoff Area =1.028 ac 0.00% Impervious Runoff Depth>2.11" Tc=5.0 min CN=83 Runoff=0.53 cfs 7,868 cf SubcatchirentC: BASIN C Runoff Area=2.459 ac 0.00% Impervious Runoff Depth >2.10" Flaw Length=211' Slope=0.0800 '1' Tc=13.3 min CN=83 Runoff=1.13 cfs 18,758 cf SubcatchmentE: BASIN E Runoff Area=3.099 ac 0.00% Impervious Runoff Depth>1.51'' Flow Length =100' Slope=0.3000 T Tc=9.4 min CN=75 Runoff=0.94 cfs 16,985 cf SubcatchmentH: BASIN H Runoff Area=13.387 ac 0.00% Impervious Runoff Depth>2.44" Flow Length=139' Slope=0.1000 '1' Tc=8.7 min CN=87 Runoff=7.98 cfs 118,782 cf SubcatchmentL: BASIN L Runoff Area=2.000 ac 0,0010 Impervious Runoff Depth>2.11" Reach R1: R1 Tc=5.0 min CN=83 Runoff -1.02 cfs 15,307 cf SubcatchmentP: BASIN P RunoffArea=32.463 ac 0.00% Impervious Runoff Depth>1.79'' Flow Length=900' Slope=4.1540 `I' Tc=15.4 min CN=79 Runoff=11.52 cfs 210,638 cf SubcatchmentXp: XP Runoff Area=5,818 sf 0.001❑ Impervious Runoff Depth>1.20" Tc=0.0 min CN=70 Runoff=0.03 cfs 581 cf SubcatchmentY-1 is Y-1 i Runoff Area=29,059 sf 100.00% Impervious Runoff Depth>3.56" Tc=5.0 min CN=98 Runoff=0.50 cfs 8,620 cf SubcatchmentY-1 p: Y -1p Runoff Area=31,454 sf 0.00% Impervious Runoff Depth>1.45" Tc=5.0 rein CN=74 Runoff=0.22 cfs 3,792 cf SubcatchmentY-2: Y-2 RunoffArea=22,700 sf 0.00% Impervious Runoff Depth>1 19" Tc=5.0 min CN=70 Runoff=0.12 cfs 2.259 cf SubcatchmentZi: ONSITE IMPERVIOUS Runoff Area=4,475 sf 100.00% Impervious Runoff Depth>3.56'' Tc=5.0 min CN=98 Runoff=0.09 cfs 1,327 cf SubcatchmentZp: ONSITE PERVIOUS Runoff Area=1,850 sf 0.0010 Impervious Runoff Depth>1.45" Tc=5.0 min CN=74 Runoff=0.01 cfs 223 cf Reach R1: R1 Avg. Depth= 0.27' Max Vel=16.78 fps Inflow=2.56 cfs 44,550 cf D=10.4" n=0.013 L=120.0' S=026727' Capacity=11.33 cfs Outflow=2.56 cfs 40,553 cf Reach R2 : R2 Avg. Depth =0.31' Max Vel=13.59 fps Inflow=2.56 cfs 40,553 cf D=10.0" n=0.013 L=570' S=!0.14937 Capacity=8.47 efs Outflow=2.56 cfs 40,550 cf Reach R3: R3 Avg. Depth=0.40' Max Vel=9.72 fps Inflow=2.56 cfs 40,550 cf D=10.0" n=0.013 L=147,0' S=0-06007' Capacity=5.37 cfs Outflow=2.56 cfs 40,536 cf Reach R4: R4 Avg, Depth=0.54' Max Vel=9,58 fps Inflow=3.57 cfs 55,843 cf D=10.4" n=0013 L=154.0' S=0,0472? Capacity=4,76 cfs Outflow=3.57 cfs 55,824 cf 214 3845 DOWNSTREAM ANALYS Type IA 24 -hr 25 -YR LAKE 0SWEG0 STORM RainfalF=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCADD 8.50 sln 405096 Oc 2047_ HydroCAD Software Solutions LLC _�- page 4 Reach R5: R5 Avg. Depth= 1.07' Max Vel=11.76 fps Inflow=15.88 cfs 286,140 cf D=18.0" n=0013 L=160.0' S=0.03107 Capacity= 18.49 cfs Outflow= 1578 cfs 286,050 cf Reach R6: DOWNSTREAM OUTFALL Avg. Depth=1.14' Max Vel=16.52 fps Inflow=23.76 cfs 404.632 cf D=18.0" n=0.013 L=145,0' S=0.06007' Capacity=25.73 cfs Outflow=23.72 cfs 404,752 cf Reach S1: S1 Avg. Depth=0.32' Max Vel=4.19 fps Inflow=0.80 cfs 12,412 cf D=10.0" n=0.011 L=235.0' S=0.01007' Capacity=2.59 cfs Outflow=0.80 cfs 12,398 Gf Reach S2: S2 Avg. Depth=0.20' Max Vel=8.08 fps Inflow=4.80 cfs 12,398 cf D=100" n=0,011 L=118,0' S=0.0625'1' Capacity=6.47 cfs Outflow=0.80 cfs 12,395 cf Reach S3: 53 Avg. Depth=0.27' Max Vel=5.27 fps Inflow=0.80 cfs 12,395 cf D=10.0" n=0.011 L=35.0' S=0-01897 Capacity=3.56 cfs Outflow=0.80 cfs 12,393 cf Reach V1: V1 Avg. Depth=0.83' Max Vel=16.62 fps inflow=11.64 cfs 212,897 cf 0=12.0" n=0.013 L=200.0' S=0.1033? Capacity= 11.45 cfs Outflow=11.62 cfs 212,839 cf Reach V2: V2 Avg. Depth=3.72' Max VeI=19.20 fps Inflow=11.62 cfs 212,839 cf D=12.0" n=0.013 L=45.0' S=0.14137 Capacity=13.39 cfs Outflow=11.62 ofs 212,827 cf Reach V3: V3 Avg. Depth=0.64' Max VeI=21 75 fps Inflow=11.62 cfs 212,827 cf D=12.0" n=0.1713 L=112.0' S=0.19147 Capacity=15.59 cfs Outflow=11.62 cfs 212,801 cf Reach V4: V4 Avg. Depth= 1.00' Max VeI=15.33 fps Inflow=11,62 cfs 212,801 cf D=92.0" n=0.013 L=1525 S=0.0879'1' Capacity= 10-56 cfs Outflow=11.36 cfs 212;750 cf Reach X1: EXISTING MAIN IN CEDAR ST Avg. Depth =0.40' Max Vel=6.37 fps Inflow=1.66 cfs 25,625 cf D=100" n=0.013 L=95.0' S=002607' Capacity=3.53 cfs Outflow=1 66 cfs 26,616 cf Link 1L: DETENTION PIPE below 1.18 cfs Inflow=0,80 cfs 12,398 cf Primary=0.80 cfs 12,398 cf Secondary=0.00 cfs O cf Total Runoff Area = 2,466,675 sf Runoff Volume = 405,141 cf Average Runoff Depth = 1,97" 98.64% Pervious = 2,433,141 sf 1.36% Impervious = 33,534 sf 215 3845 DOWNSTREAM ANALYS Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3. 80 " Prepared by AKS ENGINEERING Printed 10/16/2014 f ! droCADO 8.50 sin 005096 © 2007 H droCAD Software Solutions LLC Pa e 5 Summary for Subcatchment B: BASIN B Runoff = 0.53 cfs @ 7.95 hrs, Volume= 7,858 cf, Depths 2.11" Runoff by SBUH method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3,80" Area ac CN Description 1.028 83 ASSUME AVERAGE .25 ACRE LOT, HSG C 1.028 Pervious Area Tc Length Slope Velocity Capacity Description min (feet) {ftfft) ft/sec cfs 5.0 Direct Entry, w U O LL 216 Subcatchment B: BASIN B Hydrograph V i z o 4 5 0 ! 6 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Runoff 3845 DOWNSTREAM ANALYS Type 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 H droCADD 8.50 sln 005096 Q 2007 H droCAD Software Solutions LLC Page 6 Summary for Subcatchment C: BASIN C Runoff — 1.13 cfs @ 8.00 hrs, Volume= 18,758 cf, Depths 2.10" Runoff by SBUH method, Time Span= 0.00-24.04 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Area (ac) CN Description 2.461 83 ASSUME AVG .25 ACRE LOT, HSG C_ _ 2.461 Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ftlft) (ft/sec) (cfs) 13.3 211 0.0800 0.26 Sheet Flow, Grass: Short n= 0.150 P2= 1.90" N w V 3 0 LL Subcatchment C: BASIN C Hydrograph U 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ❑ Runoff 217 3845 DOWNSTREAM ANALYS Type lA 24 -hr 25 -YR LAKE OSWEG0 STORM Rainfall= 3.80 " Prepared by AKS ENGINEERING Printed 10/16/2014 H droCADQR 8,50 s/n 005096 © 2007 Fi droCAD Software Solutions LLC Page 7 Summary for Subcatchment E: BASIN E Runoff = 0.94 cfs @ 8.00 hrs, Volume= 16,985 cf, Depths 1.51" Runoff by SBUH method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Area (ac) CN Description 3.099 75 ASSUME AVG .25 ACRE LOT, HSG B ^� 3.099 Pervious Area Tc Length Slope Velocity Capacity Description (min) [feet](ft/ft) (ft/sec) (cfs) 9.4 100 0.3000 0.18 Sheet Flow, Woods Light underbrush n= 0.400 P2= 1.90" N V LL 218 Subcatchment E: BASIN E Hydrograph 0 1 2 3 4 5 6 7 8 9 1 ❑ 11 12 13 14 15 16 17 18 19 26 21 22 23 24 Time (hours) l- RunoN 3845 DOWNSTREAM ANALYSType lA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 H droCAD® 8.50 sln 005096 0 2007 H droCAD Software Solutions LLC Page 8 Summary for Subcatchment H: BASIN H Runoff = 7.98 cfs @ 7.99 hrs, Volume= 118,782 cf, Depths 2.44" Runoff by SBUH method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Area(ac)--CN Description ' 13.387 87 ASSUME AVG .25 ACRE LOT, HSG D _ 13.387 Pervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft) (fUsec) (cfs 8.7 139 0.1000 0.27 Sheet Flow, Grass. Short n=0,150 P2=1.90" Subcatchment H: BASIN H Hydrograph U I z j 4 5 b 1 8 9 1❑ 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 219 3845 DOWNSTREAM ANALYS Type 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10116/2014 H droCADO 8.50 sin 005096 © 2007 Fi droCAD Software Solutions LLC Page 9 Summary for Subcatchment L: BASIN L Runoff - 1.02 cfs @ 7.95 hrs, Volume= 15,307 cf, Depths 2.11" Runoff by SBUH method, Time Span= 0.00-24,00 hrs, dt= 0,01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall -3.80" _ Area (ac) CN _ Description _ 2.000 83 ASSUME AVERAGE .25 ACRE LOT HSG C 2.000 Pervious Area Tc Length Slope Velocity Capacity Description min feet) (fUft) (ft/sec cfs 5.0 Direct Entry, Subcatchment L: BASIN L Hydrograph L) 1 d s 4 s S 7 8 9 10 11 12 13 14 15 16 17 18 18 20 21 22 23 24 Time (hours) 220 D Runoff 3845 DOWNSTREAM ANALYS Type 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 tydroCADO 8.50 sln 005096 D 2007 HydroCAD Software Solutions LLC Page 10 Summary for Subcatchment P: BASIN P Runoff - 11.52 cfs @ 8.00 hrs, Volume= 210,638 cf, Depths 1.79" Runoff by SBUH method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Area ac CN Description 5.785 74 FREEPONS PARK (OPEN SPACE - GRASS COVER > 75%) * 26.678 80 ASSUMES 75% PERVIOUS -AVG .5 ACRE LOT, HSG C 32.463 79 Weighted Average 32.463 Pervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft(ft/sec)_ (cfs) 13.7 300 0.1500 0.37 Sheet Flow, PARK SHEET Grass: Short n=0.150 P2=1.90" 1.7 600 0.1500 5.81 Shallow Concentrated Flow, PARK SHALLOW Grassed Waterwav Kv= 15.0 fos 15.4 900 Total Subcatchment P: BASIN P Hydrograph U 1 e 3 4 s 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) © Runoff 221 3845 DOWNSTREAM ANALYSType 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfa11=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 H droCADO 8.50 sln 005096 a 2007 H droCAD Software Solutions LLC Page 11 Summary for Subcatchment Xp: XP Runoff = 0.03 cfs @ 7.97 hrs, Volume= 581 cf, Depths 1.20" Runoff by SBUH method, Time Span= 0,00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Areas CN Descri tion 5,818 70 BRUSH WEED GRASS MIXTURE 50-75% 5,818 Pervious Area Subcatchment Xp: XP Hydrograph 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 222 Q Runoff 3845 DOWNSTREAM ANALYS Type 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/18/2014 HydroCAD(b 8.50 stn 005996 © 2007 HydroCAD Software Solutions LLC Page 12 Summary for Subcatchment Y-1 is Y-1 i Runoff = 4.80 cfs @ 7.88 hrs, Volume= 8,820 cf, Depths 3.56" Runoff by SBUH method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Area (sf] CN Description ` 29,059 98 29,059 Impervious Area Tc length Slope Velocity Capacity Description (min) (feet) (fUft) (ftlsec)_ (cfs) 5.0 Direct Entry, Suhcatchment Y-1 is Y-1 i Hydrograph 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 26 21 22 23 24 Time (hours) ❑ Runoff 223 3845 DOWNSTREAM ANALYSType 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfaf1=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 H droCAD® 8.50 sln 005096 C 2007 H droCAD Software Solutions LLC Page 13 Summary for Subcatchment Y-1 p: Y-1 p Runoff — 0.22 cfs @ 8.03 hrs, Volume= 3,792 cf, Depths 1.45" Runoff by SBUH method, Time Span= 0.00-24.00 hrs, dt= 0,01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Area (sfl CN ❑escri tion 31,454 74 GOOD CONDITION GRASS >75% COVER HSG C 31,454 Pervious Area Tc Length Slope Velocity Capacity Description min feet(ft/ft) (ft/sec) cfs 5.0 Direct Entry, Subcatchment Y-1 p: Y-1 p Hydrograph u 1 2 s 4 5 6 7 S 9 1Q 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 224 Runoff 3845 DOWNSTREAM ANALYS Type IA 24 -hr 25 -YR LAKE OSWEGG STORM Rainfall= 3. 80 " Prepared by AKS ENGINEERING Printed 10/16/2014 H droCAD0 8.50 s/n 005096 (D2007 N droCAD Software Solutions LLC Page 14 Summary for Subcatchment Y-2: Y-2 Runoff = 0.12 cfs @ 8.00 hrs, Volume= 2,259 cf, Depths 1.19" Runoff by SBUH method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Area_(sCN Description 22,700 70 BRUSH -WEED GRASS MIXTURE 50-75% 22.740 Pervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft ftlsec cfs 5.0 Direct Entry, 9 LL Subcatchment Y-2: Y-2 Hydrograph 0.126 Rug o7r 0.12 0.12 Cfs 0.115 Type IA 24 -hr 25 -YR LAKE OSWEGO STORM 0.11 Rainfall=3.80" 0.105 Runoff Area=22,700 sf 0.1 Runoff Volume=2,259 cf 0.085 I Runoff Depth>1.19" 0.09 0.085 Tc=5A min n na CN=70 Id 0.015 4.01 0, 005 0 0 1 2 3 4 5 6 7 8 9 1 11 12 73 74 15 16 17 18 19 20 21 22 23 24 Time (hours) 225 3845 DOWNSTREAM ANALYS Type lA 24 -hr 25 -YR LAKE OSWEG0 STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCAOS 8.50 s/n 005096 ©2007 HydroCAD Software Solutions LLC Page 15 Summary for Subcatchment Zi: ONSITE IMPERVIOUS NOT DETAINED Runoff — 0.09 cfs @ 7.88 hrs, Volume= 1,327 cf. Depths 3.56'' Runoff by SBUH method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSVVEGO STORM Rainfall=3.80" Areas CN Description 4,475 98 4,475 Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 5.0 Direct Entry, Subcatchment ZI: ONSITE IMPERVIOUS NOT DETAINED Hydrograph 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 226 ❑ Runoff 3845 DOWNSTREAM ANALYS Type lA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCADO 8_50 s/n 005096 © 2007 HydroCAD Software Solutions LLC Paqe 16 Summary for Subcatchment Zp: ONSITE PERVIOUS FLOWING OFFSITE Runoff -- 0.01 cfs @ 8.00 hrs, Volume= 223 cf, Depths 1.45" Runoff by SBl1H method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Areas CN Description 1,850 74 GRASS GOOD CONDITION >75% COVER, HSG C 1,850 Pervious Area .._ Tc Length Slope Velocity Capacity Description min feet(ft/ft) (ft/sec) cfs 5.0 Direct Entry, Subcatchment Zp: ONSITE PERVIOUS FLOWING OFFSITE Hydrograph 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time [hours] U Runoff 227 3845 DOWNSTREAM ANALYS Type 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3. 80 " Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCAD® 8-50 sln 005096 © 2007 HydroCAD Software Solutions LLC Page 17 Summary for Reach R1: R1 Inflow Area = 218,819 sf, 15.33% Impervious, Inflow Depth > 2.22" for 25 -YR LAKE OSWEGO STORN Inflow = 2.5E cfs @ 8.00 hrs, Volume= 40,560 cf Outflow = 2.56 cfs @ 8.00 hrs, Volume= 40,553 cf, Atten= 0%, Lag= 0.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 16.78 fps, Min. Travel Time= 0.1 min Avg. Velocity = 9.67 fps, Avg. Travel Time= 0.2 min Peak Storage= 18 cf @ 8.00 hrs, Average Depth at Peak Storage= 0.27' Bank -Full Depth= 0.83', Capacity at Bank -Full= 11.33 cfs 10.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 120.0' Slope= 0.26727 Inlet Invert= 257.07, Outlet Invert= 225.00' 2 W 228 Reach R1: R1 Hydrograph .®Inflow a — _ i !-p 0.27' Max Vel=1 6.78 +, D=10.0" n=0.01 20.0' 1.33 cfs �j fj�/fig ._--- 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ®Inflow 0 Outflow 3845 DOWNSTREAM ANALYS Type 1A 24 -hr 25 -YR LACE OSWEGO STORM Rainfall=3. 80 " Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCAD@ 8.50 sln 005098 Q 2007 HydroCAD Software Solutions LLC Page 18 Summary for Reach R2: R2 Inflow Area = 218,819 sf, 15.33% Impervious, Inflow Depth > 2.22" for 25 -YR LAKE OSWEGO STORK Inflow = 2.58 cfs @ 8.00 hrs, Volume= 40,553 cf Outflow = 2.58 cfs @ 8.00 hrs, Volume= 40,550 cf, Atten= 0%, Lag= 0.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 13.59 fps, Min. Travel Time= 0.1 min Avg. Velocity = 7.88 fps, Avg. Travel Time= 0.1 min Peak Storage= 11 cf @ 8.00 hrs, Average Depth at Peak Storage= 0.31' Bank -Full Depth= 0.83', Capacity at Bank -Full= 8.47 cfs 10.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 57.0' Slope= 0.14937 Inlet Invert= 224.70', Outlet Invert= 218.19' Reach R2: R2 Hydrograph M Inflow Outflow ■ rf Inflow + l %Max VeI=1 �0 ra ' D=10.02 mm % rlz/,. 11 + =8.41 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 229 3845 DOWNSTREAM ANALYS Type 1R 24 -hr 25 -YR LR KE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCAD® 8.50 s/n 005096 © 2007 HydroCAD Software Solutions LLC _ Page 19 Summary for Reach R3: R3 Inflow Area = 218,819 sf, 15,33% Impervious, Inflow Depth a 2.22" for 25 -YR LAKE OSWEGO STORK Inflow = 2.56 cfs @ 8.00 hrs, Volume= 40,550 of Outflow - 2.56 cfs @ 8.01 hrs, Volume= 40,536 cf, A#ten= 0%, Lag= 0.4 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 9.72 fps, Min. Travel Time= 0.3 min Avg. Velocity = 5.71 fps, Avg. Travel Time= 0.4 min Peak Storage= 39 cf @ 8.00 hrs, Average Depth at Peak Storage= 0.40' Bank -Full Depth= 0.83', Capacity at Bank -Full= 5.37 cfs 10.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 147,0' Slope= 0.0600T Inlet Invert= 216.49', Outlet Invert= 207.37' 0 U. 230 2 0 Reach R3: R3 Hydrograph 2.56 cfs Inflow Area=218,819 sf t -p 1 1 % D=10.0" n=0.01 S=0.0600 acitv=6.37 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) I Inflow CI outflow 3845 DOWNSTREAM ANALYS Type lA 24 -hr 25 -YR LAKE OSWEG0 STORM Rainfall=3. 80 " Prepared by AKS ENGINEERING Printed 10/16/2014 H droCADO 8.50 sln 005095 @ 2007 H droCAD Software Solutions LLC Pacie 20 Summary for Reach R4: R4 Inflow Area = 305,939 sf, 10.96% Impervious, Inflow Depth > 2.19" for 25 -YR LAKE OSWEGO STORIV Inflow - 3.57 cfs @ 8.00 hrs, Volume= 55,843 cf Outflow = 3.57 cfs @ 8.00 hrs, Volume= 55,824 cf, Atten= 0%, Lag= 0.2 min Routing by Star-Ind+Trans method, Time Span= 0,00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 9.58 fps, Min. Travel Time= 0.3 min Avg. Velocity = 5.72 fps, Avg. Travel Time= 0.4 min Peak Storage= 57 cf @ 8.00 hrs, Average Depth at Peak Storage= 0.54' Bank -Full Depth= 0.83', Capacity at Bank -Full= 4.76 cfs 10.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 154.0' Slope= 0.04727 Inlet Invert= 207.37', Outlet Invert= 200.10' Reach R4: R4 Hydrograph El Inflow 0 Outflow Inflow A _ 1 . a sf jAvg. r . 1 r� i%Max Vel=9.58 D= 10. n=0.013 54.01 S=0.0472 71 ..__""--rar-ht7-4.76 ds 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hoursy 231 3845 DOWNSTREAM ANALYSType 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/1612014 H droCAOD 8.50 sln 005096 @2007 H droCAD Software SoUions LLC Pacie 21 Summary for Reach R5: R5 Inflow Area = 1,883,538 sf, 1.78% Impervious, Inflow Depth > 1.82" for 25 -YR LAKE OSWEGO STORK Inflow = 15.88 cfs @ 7.98 hrs, Volume= 286,140 cf Outflow = 15.78 cfs @ 7.98 hrs, Volume= 286,050 cf, Atten= 1 %, Lag= 0.2 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.06 hrs, dt= 0.01 hrs Max. Velocity= 11.76 fps, Min. Travel Time= 0.2 min Avg. Velocity = 7.15 fps, Avg. Travel Time= 0.4 min Peak Storage= 215 cf @ 7.98 hrs, Average Depth at Peak Storage= 1.07' Bank -Full Depth= 1.50', Capacity at Bank -Full= 18.49 cfs 18.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 160.0' Slope= 0.0310'f Inlet Invert= 198.46', Outlet Invert= 193.50' Reach R5: R5 Hydrograph fl 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 232 ® Inflow ❑ outflow 3845 DOWNSTREAM ANALYS Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCAD® 8.50 s/n 005095 QQ 2007 HydroCAD Software Solutions LLC Page 22 Summary for Reach R6: DOWNSTREAM OUTFALL Inflow Area = 2,466,675 sf, 1.36% Impervious, Inflow Depth > 1.97" for 25 -YR LAKE OSWEGO STORN Inflow = 23.76 cfs @ 7.98 hrs, Volume= 404,832 cf Outflow = 23.72 cfs. @ 7.98 hrs, Volume= 404,752 cf, Atten= 0%, Lag= 0.2 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Veiocity= 16.52 fps, Min. Travel Time= 0.1 min Avg. Velocity = 10.08 fps, Avg. Travel Time= 0.2 min Peak Storage= 208 cf @ 7.98 hrs, Average Depth at Peak Storage= 1.14' Bank -Full Depth= 1.50', Capacity at Bank -Full= 25.73 cfs 18.0" Diameter Pipe, n=0.013 Concrete pipe, straight & clean Length= 145.0' Slope= 0-06007' Inlet Invert= 193.20', Outlet Invert= 184.50' Reach R6: DOWNSTREAM OUTFALL Hydrograph MInflow ❑ Outflow `InflowArea .. 22- i�.. `.'Avg. ■- fMax VeI=1 6.52 fps n=0.01 ` 5.73 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 233 3845 DOWNSTREAM ANALYS Type IA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCAD@ 8.50 s!n 005096 © 2007 HydroCAD Software Solutions LLC Page 23 Summary for Reach S1: S1 Inflow Area = 60,513 sf, 48.02% Impervious, Inflow Depth > 2.46" for 25 -YR LAKE OSWEGO STORK Inflow = 0.80 cfs @ 7.92 hrs, Volume= 12,412 cf Outflow = 0.80 cfs @ 7.95 hrs, Volume= 12,398 cf, Atten= 0%, Lag= 1.6 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 4.19 fps, Min. Travel Time= 0.9 min Avg. Velocity = 2.46 fps, Avg. Travel Time= 1.6 min Peak Storage= 45 cf @ 7.93 hrs, Average Depth at Peak Storage= 0.32' Bank -Full Depth= 0.83', Capacity at Bank -Pull= 2,59 cfs 10.0" Diameter Pipe, n= 0.011 PVC, smooth interior Length= 235.0' Slope= 0.0100'1' Inlet Invert= 268.00', Outlet Invert= 265.65' 0.75 Q7 a.6s 0.6 0.55 0.5 3 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 234 Reach S1: S1 Hydrograph Avg. Depth=0.32' Max Vel=4.19 fpsl 0.0" r r' %f r S=0.0100 f' 'Y e * a cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Ito Inflow ❑ Out1 3845 DOWNSTREAM ANALYS Type lA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 H droCAD® 8.50 sln 005096 ©2007 N droCAD Software Solutions LLC Page 24 Summary for Reach S2: S2 Inflow Area = 60,513 sf, 48.02% Impervious, Inflow Depth > 2.46" for 25 -YR LAKE OSWEGO STORN Inflow = 0.80 cfs @ 7.95 hrs, Volume= 12,398 cf Outflow = 0.80 cfs @ 7.95 hrs, Volume= 12,395 cf, Atten= 0%, Lag= 0.4 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 8.08 fps, Min. Travel Time= 0.2 min Avg. Velocity = 4.69 fps, Avg. Travel Time= 0.4 min Peak Storage= 12 cf @ 7.95 hrs, Average Depth at Peak Storage= 0.20' Bank -Full Depth= 0.83', Capacity at Bank -Full= 6.47 cfs 10.0" Diameter Pipe, n= 0.011 PVC, smooth interior Length= 118.0' Slope= 0.0625T Inlet Invert= 265.50', Outlet Invert= 258.13' Reach S2: S2 Hydrograph 1: 1 :1 1 r Inflow_ ■ I s ■ 1 i 1 Max i I : ■ I 1 =0.01 1 45r 0-4 i/ I . � S=0.0625 0,257 ■ . 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) in Inflow 0 outflow 235 3845 DOWNSTREAM ANALYSType 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCADC 8.50 sln 005096 © 2007 HydroCAD Software Solutions LLC Page 25 Summary for Reach S3: S3 Inflow Area = 60,513 sf, 48.02% Impervious, Inflow Depth a 2.46" for 25 -YR LAKE OSWEGO STORK Inflow = 0.80 cfs @ 7.95 hrs, Volume= 12,395 cf Outflow = 0.80 cfs @ 7.96 hrs, Volume= 12,393 cf, Atten= 0%, Lag= 0.2 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 5.27 fps, Min. Travel Time= 0.1 min Avg. Velocity = 3.08 fps, Avg. Travel Time= 0.2 min Peak Storage= 5 cf @ 7.96 hrs, Average Depth at Peak Storage= 0.27' Bank -Full Depth= 0.83', Capacity at Bank -Full= 3.56 cfs 10.0" Diameter Pipe, n= 0.011 PVC, smooth interior Length= 35.0' Slope= 0.0189 'P Inlet Invert= 257.93', Outlet Invert= 257.27' Reach S3: S3 Hydrograph .8 t :t Inflow ' ■ j Avg. - ■ Max Vel=5.27 fps 5- 1 ' 1 0.35 L //L S=0.01■ 02 0.1 JJJJJ ... :_ri JJfii� 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 236 D Inflow C3 Outflow 3845 DOWNSTREAM ANALYSType !A 24-hr25-YR LAKE OSWEGO STORM Rainfa11=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCADO 8.50 sln 005096 © 2007 HydroCAD Software Solutions LLC Page 26 Summary for Reach V1: V1 Inflow Area = 1,436,788 sf, 00.00% Impervious, Inflow Depth > 1.78" for 25 -YR LAKE OSWEGO STORN Inflow = 11.64 cfs @ 8,00 hrs, Volume= 212,897 cf Outflow = 11.62 cfs @ 8.01 hrs, Volume= 212,839 cf, Atten= 0%, Lag= 4.4 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 16.62 fps, Min. Travel Time= 0.2 min Avg. Velocity = 11.84 fps, Avg. Travel Time= 0.3 min Peak Storage= 140 cf @ 8.01 hrs, Average Depth at Peak Storage= 0.83' Bank -Full Depth= 1.00', Capacity at Bank -Full= 11.45 cfs 12.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 200.0' Slope= 0.1033'1' Inlet Invert= 263.30', Outlet Invert= 242.64' Reach V1: V1 Hydrograph 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) El Inflow © outflow 237 3845 DOWNSTREAM ANALYS Type IA 24 -hr 25 -YR LR KE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCADO 8.50 sln 005096 © 2007 HydroCAD Software Solutions LLC Page 27 Summary for Reach V2: V2 Inflow Area = 1,436,788 sf, 0.00% Impervious, Inflow Depth > 1.78" for 25 -YR LAKE OSWEGO STORIV Inflow = 11.62 cfs @ 8.01 hrs, Volume= 212,839 cf Outflow - 11.62 cfs @7a 8.01 hrs, Volume= 212,827 cf, Atten= 0%, Lag= 0.1 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 19.20 fps, Min. Travel Time= 0.0 min Avg. Velocity = 13.27 fps, Avg. Travel Time= 0.1 min Peak Storage= 27 cf @ 8.01 hrs, Average Depth at Peak Storage= 0.72' Bank -Full Depth= 1.00', Capacity at Bank -Full- 13.39 cfs 12.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 45.0' Slope= 0.1413 '1' Inlet Invert= 242,34', Outlet Invert= 235.98' 1 1 7 1 238 Reach V2: V2 Hydrograph 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 26 21 22 23 24 Time (hours) N Inflow ❑ outflow 3845 DOWNSTREAM ANALYSType lA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 HydroCAD® 8.50 sln 005096 © 2007 HydroCAD Software Solutions LLC _ Page 28 Summary for Reach V3: V3 Inflow Area = 1,436,788 sf, 0.00% impervious, Inflow Depth > 1.78" for 25 -YR LAKE OSWEGO STORN Inflow = 11.52 cfs @ 8.01 hrs, Volume= 212,827 cf Outflow = 11.52 cfs @ 8.01 hrs, Volume= 212,801 cf, Atten= 0%, Lag= 0.2 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.04 hrs, dt= 0.01 hrs Max. Velocity= 21.75 fps, Min. Travel Time= 0.1 min Avg. Velocity = 14.81 fps, Avg. Travel Time= 0.1 min Peak Storage= 50 cf @ 8.01 hrs, Average Depth at Peak Storage= 0.54' Bank -Full Depth= 1.00', Capacity at Bank -Full= 15.59 cfs 12.0" Diameter Pipe, n= 0,013 Concrete pipe, straight & clean Length= 112.0' Slope= 0.1914'1' Inlet Invert= 235.88', Outlet invert= 214.44' Reach V3: V3 Hydrograph 9 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ® Inflow 11 Outflow 239 3845 DOWNSTREAM ANALYSType lA 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 Ff droCAD® 8.50 stn 005096 © 2007 Fi droCAD Software Solutions LLC Page 29 Summary for Reach V4: V4 Inflow Area = 1,436,788 sf, 0,00% Impervious, Inflow Depth > 1.78" for 25 -YR LAKE OSWEGO STORIV Inflow - 11.62 cfs @ 8.01 hrs, Volume= 212,801 cf Outflow = 11.36 cfs @ 7.98 hrs, Volume= 212,750 cf, Atten= 2%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 15.33 fps, Min. Travel Time= 0.2 min Avg. Velocity = 11.14 fps, Avg. Travel Time= 0.2 min Peak Storage= 128 cf @ 7.99 hrs, Average Depth at Peak Storage= 1,00' Bank -Full Depth= 1.00', Capacity at Bank -Full= 10.56 cfs 12.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 162.5' Slope= 0.08797 Inlet Invert= 214.34', Outlet Invert= 200.06' 13-. 1 11.62 cfs 12 11.36 cfs 11 KM u 7 a 6 LL E 240 Reach V4: V4 Hydrograph Inflow Area=11436,788 sf Avg. Depth=1.00' Max Vel=15.33 fps D=12.0" n=0.013 L=162.5' S=0.0879 11' city=10.58 cfs 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ® Inflpw ❑ Outflow 3845 DOWNSTREAM ANALYS Type 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.801" Prepared by AKS ENGINEERING Printed 10/1612014 H droCAD(D 8.50 sln 005096 (9 2007 N droCAD Software Solutions LLC Page 30 Summary for Reach X1: EXISTING MAIN IN CEDAR ST Inflow Area = 151,981 sf, 0,00% Impervious, Inflow Depth > 2.10" for 25 -YR LAKE OSWEGO STORK Inflow - 1.66 cfs @ 8.00 hrs, Volume= 26,625 cf Outflow = 1.66 cfs @ 8.00 hrs, Volume= 26,616 cf, Atten= 0%, Lag= 0,2 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Max. Velocity= 6,37 fps, Min. Travel Time= 0.2 min Avg. Velocity = 4.00 fps, Avg. Travel Time= 0.4 min Peak Storage= 25 cf @ 8.00 hrs, Average Depth at Peak Storage= 0.40' Bank -Full Depth= 0.83', Capacity at Bank -Full= 3.53 cfs 10.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 95.0' Slope= 0.02607 Inlet invert= 259.62', Outlet Invert= 257,15` Reach X1: EXISTING MAIN IN CEDAR ST Hydrograph 1.66 cfs Inflow Area=151,981 sf Avg. Depth=0.40' Max Vel=8.37 fps n=0.013 !i L=95.0' .r 0 1 2 3 4 5 6 7 8 9 1D 11 12 i3 14 15 16 17 18 19 20 2i 22 23 24 Time jhours) p Inflow 0 outflow 241 3845 DOWNSTREAM ANALYS Type 1A 24 -hr 25 -YR LAKE OSWEGO STORM Rainfall=3.80" Prepared by AKS ENGINEERING Printed 10/16/2014 Hydro_CADO 8.50 sln 005096 © 2007 HydroCAD Software Solutions LLC Page 31 Summary for Link 1 L: DETENTION PIPE Inflow Area = 60,513 sf, 48,02% Impervious, Inflow Depth > 2.48" for 25 -YR LAKE OSWEGO STORN Inflow = 0.80 cfs @ 7.95 hrs, Volume= 12,398 cf Primary = 0.80 cfs @ 7.95 hrs, Volume= 12,398 cf, Atten= 0%, Lag= 0.0 min Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0 cf Primary outflow = Inflow below 1.18 cfs, Time Span= 0.00-24.00 hrs, dt= 0.01 hrs Link 1 L: DETENTION PIPE Hydrograph 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) 242 p inflow ❑ Primary D 5ecandary Numano lu, Jessica From: Chris Goodell <chrisg@aks-eng.com> Sent: Wednesday, November 05, 2014 7:46 AM To: Numanoglu, Jessica Subject: FW: Question about moving existing house at 850 Cedar St Hi Jessica: In talking with Roger, we wanted to request that there aren't any conditions of approval requiring that the existing house be "demolished" or something similar that could preclude efforts to retain the house on site as described below. We know that there are a number of details that would need to be worked out to make that happen, some of which you have described below, but we just wanted to do what we could at this point to ensure that the conditions themselves don't somehow require this. You may have already been thinking about this, but I wanted to get it in front Of you also. Please let me know if you think this will be ok. Also, I wanted to request copies of any correspondence that you receive on the application. Please let me know if you can do this also. If you have any questions, please let me know. Thanks for your help. Chris Goodell - AICP, LEEDAP, Associate A r AKS ENGINEERING & FORESTRY NEW ADDRESS & PHONE EFFECTIVE 4/28/2014 12955 SW Herman Road, Suite 100 Tualatin, OR 97062 P: 503.563-6151 F: 503.563-6152 www.aks-eng.com I Chrisg@aks-eng.com Offices in: Tualatin, OR I Salem, OR I Vancouver, WA NOTICE: This communication may contain privileged or other ccnfidential information. IF you have received it in error, please advise the sender by reply a -mail and immediately delete the message and any attachments without copying or disclosing the contents. AKS Engineering and Forestry shall not be liable for any changes made to the electronic data transferred. Distribution of electronic data to Others is prohibited without the express written consent of AKS Engineering and Forestry. Monty Hurley - PE, PLS, Principal F�J AKS ENGINEERING & FORESTRY 12965 5W Herman Road, Suite 100 Tualatin, OR 97062 P: 503.563.6151 F: 503.553.6152 www.aks-eng.corn I monty@aks-eng-com EXHIBIT F-8 LU 14-0046 43 Z 0= Offices in: Tualatin, OR I Salem, OR G Vancouver, WA NOTICE: This communication may contain privileged or other confidential information, If you have received it in error, please advise the sender by reply a -mail and immediately delete the message and any attachments without copying or disclosing the contents. AKS Engineering and Forestry shall not be liable for any changes made to the electronic data transferred. Distribution of electronic data to others is prohibited without the express written consent of AKS Engineering and Forestry. From: Numanoglu, Jessica(mailto:inumanoglu@ci.oswego.or.us] Sent: Monday, November 03, 2014 5:14 PM To: dc-bbiefcraig@gmail.com Cc: Monty Hurley Subject: Question about moving existing house at 850 Cedar 5t Debbie, I am following up on our phone conversation earlier this afternoon about the possibility of moving the existing house at 850 Cedar Street onto Lots 7 and 8 after the subdivision is approved. As we discussed, the minimum density for the subdivision is eight lots and eight lots are proposed in compliance with that standard. You wondered whether there was any way to allow the house to occupy two lots in the subdivision without violating the minimum density standard. I brought this issue to our staff meeting this afternoon, which the Deputy City Attorney attended, and it turns out that minimum density applies at the time of lot creation, but once the lots are created, an owner is not stopped from consolidating one or more lots after the fact. Lot consolidation is done through the County and does not require any land use review by the City. 5o the short answer to your question is yes, there is a possibility that you could move the existing house onto tots 7 and 8 after the subdivision plat is recorded and you consolidate Lots 7 and 8. 1 believe you would just need permits from the Building Division to move the house and Planning would verify that ali dimensional standards (setbacks, lot coverage, etc.) are met as part of the building permit review. Having said that, one problem that would need to be addressed is the timing of the house move. In order to record a subdivision plat, the existing structures on the site have to be removed. In fact, that is one of the conditions of approval of the subdivision. In order to allow the house to stay until after the subdivision is recorded and Lots 7 and 8 can be consolidated, we would need to impose a condition of approval to require the house move to occur prior to the issuance of a building permit on any of the lots instead of before the plat is recorded. If you are serious about moving the house, you should address it as part of the applicant's presentation at the public Bearing so that appropriate conditions of approval can be added. But before that, I would check with Clackamas County to be sure they don't have any problem recording the subdivision plat with an existing dwelling on the site. If you would like to meet to discuss this further, I am availahle on Friday as you initially inquired. Just confirm the day and time and I can add it to my calendar. Best, .Jessica Numanoglu I Senior Planner okL� Q� 503.635.0283 � ., ,%� � ww►y.ci.aswego,or.us_ 1 0' 380 A Avenue oov, PO BOX 369, bake Oswego OR 97034 CG 244