HomeMy WebLinkAbout2021-08-17_Ockert_(MH) stormwater key issue From: fanfh-carole(aleurooa.com
To: Olson, Erik;Sieael.Scot
Cc: bobandmianon(cacomcast.net;randvarthur7(caamail.net
Subject: (MH)stormwater key issue
Date: Tuesday,August 17,2021 2:45:38 PM
Attachments: stormwater ex.937 9th.ona
Hi Erik,
Knowing that stormwater is likely shifted to our Aug.24th MH meeting,I
would like to cover an item in the staff Key Issue#3 memo.A quote from
the memo below:
"...The stormwater code requires that new developments and redevelopment
projects over a certain size manage all stormwater on the lot.These
requirements are triggered for any project that creates more than 1,000
square feet of new impervious surface area,and any remodel that alters
3,000 square feet or more of existing imperious area.The code requires
applicants to submit a site assessment,stormwater system design,and
other analyses to demonstrate compliance with the code...."
This functionally tells our committee a message about structures,sizing,
and stormwater,that when it comes to code,LO has got it taken care of on
site or the development doesn't happen.That certainly gives us as
committee members a sense of reliance and security when it comes to new
builds in our neighborhoods.However the statement I have quoted seems to
be lacking something,because it is not covering a current stormwater
reality.I have attached the image for your reference.
In this new build,you will see that there are two pipes openings in the
cement stormwater holding tank.All site generated stormwater is directed
into this holding tank.The top pipe opening is an infill for a french
drain off a to be poured driveway.The lower pipe opening has been
trenched to pour into the sensitive lands on the far side of the alley.
5.2.Downstream Conveyance
Treated stormwater runoff leaving the lined vegetated flow through planter
will be routed through a 0.50-inch flow control orifice prior to being
conveyed to the new outfall on the east side of the public alley.The
planned storm outfall location will direct stormwater to the existing
Tryon Creek drainage. Should the planters' flow control orifice become
plugged,overflow stormwater will be conveyed through the planter via an
overflow riser located within the planter.
I have reviewed the required stormwater report.This approach was staff
approved.The developer was not told to right size the building for the
lot such that expected development created runoff would be contained on
site.The developer was given permission to run all site stormwater
through a pipe into existing Tryon Creek drainage in an area that is
sensitive lands. So back to my comment,that apparently there is more that
needs to be said about stormwater code that is not in the Key Issues#3
statement.
I prefer the committee get a full understanding of our stormwater code
approach before we start making recommendations about other code that
directs development right sizing.We need to understand when staff
approves systems for handling stormwater that is not contained on site
especially when the runoff is onto sensitive lands.I'm not arguing you
shouldn't put stormwater runoff from a new home into sensitive lands.What
I am saying is that there is something missing from the description of LO
code as stated and perhaps we can get more delineation before the meeting
next week.It would be good for our committee to walk though this example
next week with understanding rather than confusion.
Thanks,
Carole
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