bld20150278-Le-Stormwater comments only-email 09.28.2015.pdf
From:McConnell, Jeanie
To:"marlin.g@gabbertarchitects.com"
Subject:FW: bld20150278 - Le single family residence
Date:Monday, September 28, 2015 2:08:06 PM
Attachments:Cat2_detention_example.pdf
Cat2_Det example_WWHM.PDF
Hello,
It looks like I had an incorrect email address for David Pagel. Trying again
Thank you,
Jeanie
From: McConnell, Jeanie
Sent: Monday, September 28, 2015 2:05 PM
To: 'david.p@gabbertarchitects.com'
Cc: Lambert, Jennifer
Subject: bld20150278 - Le single family residence
Good afternoon,
The Engineering Division has not yet been able complete a full review of the permit application
information resubmitted for the Le single family residence at 7317 Lake Ballinger Way. However,
the City’s Stormwater Engineer Program Manager, Jerry Shuster, has been able to complete his
review. While these comments are normally sent out in conjunction with the main engineering
review, due to our backlog of project reviews we felt it could be more efficient for you if we
provided these comments to you now. These comments have been provided below and will again
be included with the main engineering review comment letter once that review is complete.
The project classifies as a Category 2 Small Site Project. This being so, there needs to be:
1.An assessment of the applicability of Small Site Minimum Requirements (MR) #1-10 in
Section 5.0, page 29-30 of the Edmonds Stormwater Code Supplement (ESCS).
2.A discussion on how the design meets the applicable MRs in Section 5.0, page 29-30 of
the ESCS. See enclosed example for streamlined format.
As described in Section 5.6.2.2 of the ESCS, bioretention systems (aka rain gardens) with
overflows (i.e., systems not providing 100 percent infiltration) should not be used in the
Lake Ballinger basin due to potential phosphorus export. A small detention system meeting
the flow control standards found in Section 5.7.2 of the ESCS may be considered (note: you
do not have to meet the Ecology flow control standards, but you do have to use the WWHM
or MGS Flood model per ESCS Section 5.7.3.1 – See attached example). The minimum
orifice size is 0.5 inch. If you are unable to meet the flow control standards using a 0.5 inch
orifice with a head of 3 feet, the design will be deemed in compliance. The underground
power cable should not be placed under any stormwater management facility.
The bottom of the proposed “Gravel detention trench” to manage the roof water is at
elevation 282.00 (ft NGVD88). For a good part of the winter months, the lake level will be at
or above this level and this system not operate properly. The designer may consider a
dispersion trench with a grade board north of the garage and west of the house. It does not
need to be modeled if it is designed per BMP T5.10 in Section 5.3.1 , Volume V, of the 2005
Ecology Stormwater Management Manual for Western Washington.
Feel free to contact Jerry Shuster directly with any questions you may have regarding these
comments. Jerry can be reached at 425-771-0220 or jerry.shuster@edmondswa.gov
Please let me know if you have any other questions.
Regards,
Jeanie
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