10521 19TH AVE SE 2022-05-23 - Laserfiche WebLink

PUBLIC WORKS b. Please see all redlines on the attached plans for required corrections in addition to all comments listed below. Frequently, redlines will be stand-alone and will not have an associated item in this corrections letter. Likewise, comments below may not have associated redlines. i. See redlines on Sheet 4 and 7 for comments regarding grading and curb ramps around the accessible parking stalls. Use Architectural site plan background forthe concrete walk on the south and west sides of the building. The architectural grading and ramping is shown correctly, the civils are not. Please match the architecturals and add a note/callout for the contractor to use the architectural site plan for construction of that area. 2. The comments below were generated from this project's Stormwater Reviewer. If you have any questions regarding these comments, please contact Erik Emerson with the City of Everett Surface Water Department (425-257-8995 or EEmerson @everettwa.gov). a. Drainage Report: • Update the table of contents. • Permanent Stormwater Control Plan o This section was added in the updated Drainage Report, but all of the information required per Volume I, Section 3.1.5 of the Stormwater Management Manual (SWMM) is not provided. o See Volume I, Section 3.1.5 of the SWMM for complete documentation requirements. • Exhibits o Vicinity map — Missing: the route of stormwater to Silver Lake (provided instead on separate aerial map, which is not a required exhibit) and discussion or illustration of significant geographic features and sensitive/critical areas. o Site map - Missing: drainage from the site; routes of existing, construction, and future flows at all discharge points; length of travel from the farthest upstream end of the proposed conveyance to the proposed flow control and water quality treatment BMPs. o See Volume I, Section 3.1.7 of the SWMM for the complete listing of documentation requirements. French Drain sizing calculations: o Manning n of 0.011 used for PVC pipe, but the value for PVC in DCSS Table 4.2.2(3) is 0.013. o PVC pipe sizing calculations were provided, but calculations and design details need to be provided for other components of the French Drain. Minimum Requirement (MR) #6 — Runoff Treatment o See comments below for Sheet 6. • MR #7 — Flow Control o Delineate and map the extent of the flow control bypass area and call out the acreage on one of the maps provided. o The minimum orifice size provided of 0.45 inches is lower than the allowed minimum orifice size of 0.5-inch. This smaller orifice size may be allowed if the live storage were reduced to 3 feet in accordance with Volume III, Section 3.2.4 (Control Structures) of the SWMM. o WWHM modeling to size the flow control facility must properly account for dead storage. 6;;;;�