1216 BROADWAY 2023-05-25 - Laserfiche WebLink

METHODOLOGY Drainage design for the project is based on City of Everett Municipal Code (EMC) 14.28, Surface and Storm Drainage. EMC 14.28 refers to the 2019 version of the Washington State Department of Ecology's (DOE) Stormwater Management Manual for Western Washington (Stormwater Manual) for the city's stormwater technical manual. This project is located within a Combined Sewer Collection Area and subject to different stormwater requirements, detailed in Section 6-10, Combined Sewer System, of the 2020 City of Everett Design and Construction Standards and Specifications (DCSS). The project is categorized as a redevelopment project, but falls below the threshold for flow control BMPs. The following sections address the requirements from Section 6-10 of the DCSS. STORMWATER NARRATIVE Existing Conditions The project site is currently a paved parking lot. The existing Eagles Building has been demolished as part of an earlier project. The site is bounded to the north by 12th Street, to the west by an existing paved alley, to the east by Broadway Avenue, and to the south by the Everett Food Bank building. Access to the project site is from two driveway entrances along Broadway Avenue and one entrance to the alley. Frontage improvements include sidewalk and curb along 12th Street and Broadway Avenue. The site is mostly pavement and generally slopes to the east, toward existing catch basins along the eastern edge of the site. The southwest corner of the site slopes to an existing catch basin. An existing narrow vegetated embankment is located along the southern half of the west property line. Most of the stormwater from the site pavement is intended to discharge to the surrounding catch basin structures. Except for the southwest catch basin, the catch basins are filled with debris and not operational. Stormwater drains as sheet flow onto Broadway Avenue and into the existing conveyance system, which discharges to the combined sewer system that extends south. The southwest catch basin appears to connect to the sewer service from the demolished building, which discharges to an existing combined sewer manhole in the adjacent alley. Half of the stormwater from the roof of the demolished building was discharged to the pavement through downspouts and sheet flow to Broadway. The other half drains as sheet flow to the southwest catch basin. Stormwater Site Plan 3 1216 Broadway Surface Parking Lot