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Btian Lindsay <br /> From: Brian Lindsay <draftstation@earthlink.net> <br /> Sent: Friday,August 25, 2017 2:58 PM <br /> To: 'PETER G ANDERSON' <br /> Subject: FW: Phase 1 Clearing and Grading Permit for 11229 19th Ave SE <br /> Attachments: Threshold flow chart for Silver Lake Townhouses.pdf <br /> (e_a_s e.,.. Se.4_, A 0 ' 0 1-4""1 <br /> 4 <br /> 00,...APesiocmce, , <br /> cf) <br /> Thank you <br /> Brian Lindsay <br /> BRL Services LLC <br /> 2221 Everett Ave ste#203 <br /> Everett, WA 98201 <br /> 425-259-5556 <br /> From:Sabrina Fandler [mailto:SFandler@everettwa.gov] <br /> Sent: Friday, August 25, 2017 9:03 AM <br /> To: Brian Lindsay<draftstation@earthlink.net> <br /> Cc: 'Gil Moalem'<gmoalem@gmail.com>; Grace Pollard <GPollard@everettwa.gov> <br /> Subject: RE: Phase 1 Clearing and Grading Permit for 11229 19th Ave SE <br /> Hi Brian, <br /> Please see the comments below from our stormwater group. I have a few minor redlines that I am working through but <br /> nothing very significant other than the stormwater comments listed below. <br /> I've taken a preliminary look at the revised plans and drainage report for the 11229 Townhouses project. I haven't had <br /> the opportunity to do a full review, but based on the applicants expressed urgency I am providing the following <br /> comments.These comments address significant concerns which are likely to impact the layout of the site and/or the <br /> cost of construction.Additional comments will likely be provided in the future for the details of the design. <br /> 5j7�0r sec 'P <br /> • The drainage report includes a flow chart from the 2010 stormwater manual. However the equivalent flow chart <br /> from the 2014 Ecology manual must be used and should be included in the report. (see attached)The most <br /> significant difference between the two flow charts is that the Ecology version expressly states that minimum <br /> requirements must be applied to all new and replaced hard surfaces. Since the project will remove all existing <br /> structures the minimum requirements must b;g4pplied to all impe ious and converted pervious surfaces within <br /> the project. j..-4— e,vi se-/-� <br /> • Minimum Requirements#7 requires that the predeveloped condition is forested for performing flow control <br /> calculations and detention facility sizing.The calculations submitted in the stormwater report are based on <br /> matching existing conditions.The detention facilities will need to be re-designed to match forested runoff <br /> conditions. Based on a quick WWHM analysis it appears that this change willreqire a proximately)4 times as <br /> much detention volume as is currently provided. , e✓is F'- 9t- -� <br /> • Minimum requirement#5 requires that projects provide onsite stormwater management to the extent feasible. <br /> The applicant must demonstrate compliance with the LID performance standard or employ List#2 for each type <br /> of surface within the project. If the list approach is s lected then the project must provide the first feasible BMP <br /> :Ert 4'/Tra., i tris Vi <br />