859 LOCUST ST 2022-07-20 - Laserfiche WebLink

t lily Q 0 DAVID EVANS AND ASSOCIATES INC. August 28th, 2017 Arnie Roshak, P.E. City of Everett Public Works 3200 Cedar Street Everett, WA 98201 SUBJECT: Grandview Apartments Clubhouse Arnie, This letter has been prepared in response to the following drainage comments received on August 25th, 2017 and is intended to serve as an addendum to the 4/28/17 drainage report prepared for this project: I am going to hand back the drawings for the Grandview Apartments Clubhouse and Parking. They provided the information I asked for but based on that information, they will have some issues with getting flow to the rain garden. It looks like they are discharging the flow from the parking area to the underdrain for the rain garden rather than into the rain garden at the surface. Based on their modeling, the rain garden is allowing them to meet the flow control requirement by receiving flow from 0.25 acres of impervious area, which would include both the clubhouse and parking area. That said, I only have their modeling results and not the input from WWHM, if they have modeled a bypass and can show they can achieve flow control even with bypassing the parking lot flow around the rain garden, they will need to provide the model input information showing a portion of the impervious area bypassed the rain garden(screen shots from WWHM will work). The WWHM modeling results previously provided in the drainage report did not include bypass modeling and therefore the plans have been revised in order to allow parking lot drainage to outlet at the rain garden surface. The revised rain garden design and WWHM modeling results are attached to this letter. Upon consideration of this letter and attachments, please advise us of the results of your review. Sincerely, DAVID EVANS&ASSOCIA , INC. ti ' Molver, P.E. Vice President Cc: Kirk Brooks