1415 BROADWAY CM HEATING 2023-09-25

SECTION IV: CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the Construction stormwater permit requirements for the project CM Heating is located at 1415, 1411, and 1407 Broadway,Everett,WA 98201. It is located in Section 17, Township 29 North,and Range 5 East of the Willamette Meridian in the City of Everett,Washington. The northern parcel exists as a residential property with an existing home, the center parcel exists as parking lot, and the southern parcel exists as a commercial property with an existing commercial building. The site contains one drainage that slopes to the slightly to the west. There are no critical areas located within the site. Per NRCS survey of Snohomish County, the project site contains Alderwood soils that have a hydrologic classification of Type "C". The proposal is to construct a new commercial building and parking lot. The total proposed impervious surfaces will be 15,034 SF. The access to the site will be from the alley in between Broadway and McDougal Ave. The project site is legally served by a combined storm and sanitary sewer system, in which case the stormwater standards shall be as determined by Public Works Department policy. The existing basin was modeled as existing conditions per section 6-10 of the City Design and Construction Standards and Specifications. Flow control requirements will be met by a 15 LF 6-foot diameter detention pipe on the east side of the building. The project is exempt from water quality as the project discharges to the combined sewer and any new PGHS will be minimal. A floatable materials separator and gas trap are proposed for the project. Per Vol I figure 2.4.2 of the SWMMWW, Minimum requirements #1 through #9 shall apply for this project. Refer to section 1.2 for Minimum Requirements Summary. Insight Engineering Co. -Stormwater Site Plan 3/25/2021 - 15-