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PLANS, SPECIFICATIONS AND ESTIMATE REVIEW <br />Project Title: <br />75th — Seaway Transit Center 90% Review <br />Job Charge: <br />Reviewed By: <br />Office & Mail Stop: <br />Phone: <br />Date: <br />Sheet <br />WO# <br />Erik Emerson <br />Public Works <br />425-257-8995 <br />2-14-17 <br /># <br />Sht/Pg <br />Reviewer's Comment <br />Designer's Response <br />Init. <br />62 <br />General <br />The City has adopted the 2014 Ecology Stormwater Management Manual as <br />Plans and drainage report have been <br />BJC <br />it's stormwater manual. All projects submitted for construction permit review <br />updated accordingly. <br />after January 1, 2017 must comply with the requirements in the new manual. <br />63 <br />Genral <br />The City has also published draft Design and Development Standards and <br />Plans have been updated accordingly. <br />BJC <br />Specifications (DCSS). The draft standards for stormwater facilities <br />(Chapter 4) only have been set as the City's standards. The changes include <br />revisions to the standard plan content and numbering, as well as significant <br />revisions to the text. Your proposed design must comply with the <br />requirements of the revised standard. <br />64 <br />Drainage <br />Requirement #2 The project must address all 13 SWPPP elements since the <br />Drainage report and SWPPP have been <br />BJC <br />Report — <br />design includes a rain garden. This also applies to the summary on Page 12 <br />updated accordingly. <br />p .10 <br />and the formal SWPPP provided in the Appendix. <br />65 <br />Drainage <br />Requirement #5 The report provides insufficient justification for the <br />The drainage report has been updated to <br />BJC <br />Report — <br />determination that onsite stormwater management practices are infeasible. <br />provide additional justification for LID <br />pg.10 <br />Please provide infeasibility documentation in accordance with the current <br />infeasibility. <br />Stormwater Management Manual or apply onsite stormwater management <br />BMP's in accordance with the current manual. <br />66 <br />Appendix C <br />Notes that the HGL at CB#12 is 568.85, which is not only higher than the top <br />Design has been updated to include 18-inch <br />BJC <br />— Last <br />of the detention vault, but is also higher than the rim of CB#7 and <br />pipes. The calculations were also updated, <br />page of <br />backwaters the treatment and oil control facilities. While it is unlikely that <br />bringing down the HGL considerably. <br />calcs <br />these pipes will ever need to convey an un-detained 100 year flow the <br />concern can likely be addressed by upsizing the three runs of downstream <br />pipe to 18" diameter. The structures are already Type 2 due to their depth, <br />so the difference is minimal. <br />67 <br />DR1 <br />CB#3 is shown with 4 pipes coming into a Type 1 structure. It appears that <br />CB #3 has been upgraded to a Type 2 <br />BJC <br />multiple pipes will be connected on the same side which is infeasible for a <br />structure. <br />Type 1 structure. Revise the configuration of the pipes or switch to a Type 2 <br />structure. <br />68 <br />DR2 <br />Per the current Stormwater Management Manual a high flow bypass must be <br />A high flow bypass has been added to the <br />BJC <br />provided for the Oil Water Separator (Volume V, Section 11.6, second bullet) <br />design of the Oil Water Separator. <br />unless it is necessary to locate it offline. It appears that it is feasible to <br />configure the system to bypass high flows. The bypass can be connected <br />directly to the detention vault, or back to the conveyance systeigas desired. <br />90% Seaway Review Comments.docxx &/- <br />