8920 EVERGREEN WAY THE RESERVE 2025-07-25

Stormwater Pollution Prevention Plan 2.0 Site Description 2.1 Existing Conditions The proposed site is located just northwest of Evergreen Way never the Evergreen Way and Holly Drive intersection in Everett, Washington. A site vicinity map and coordinates are provided in Appendix A. The site is 2.38 acres in size and includes assorted site concrete and asphalt. This is mostly in the form of a small parking area near the southeast property line, adjacent to Evergreen Way. The topography of the site and surrounding properties gently slopes to the southeast at the northwest and southeast portions of the site, with a moderate slope between these two areas. Soils on the surface are generally topsoil and are underlain by Glacial Till. The site is not well suited for infiltration and groundwater lies approximately 7-16.5 feet below the surface in some of the site's test pits. Runoff from the site generally slopes toward Evergreen Way. The northern most portions of the site first sheet flow onto the adjacent PUD property, but then flow down toward Evergreen Way as well. There are no critical areas on the site such as high erosion risk areas, wetlands, streams, or steep slopes. 2.2 Proposed Construction Activities The proposed development includes the construction of a four-story senior apartment building and its associated parking lot,patios, and walkways. The proposed building will be located near the southeastern property line of the site with a new asphalt paved parking lot behind the building (northwest half of the property). A stormwater detention vault will be constructed . approximately in the center of the site. New sanitary, water, electrical, gas, and storm drain utilities will also be constructed. Construction activities will include site preparation, TESC installation, demolition of existing pavements, excavation for the building foundations and pre-cast concrete stormwater vault, poured concrete foundations, wood frame building construction, site-wide grading, and asphalt paving. The schedule and phasing of BMPs during construction is provided in Section 4.0. Stormwater runoff volumes were calculated using the Western Washington Hydrology Model (WWHM). The temporary sedimentation pond that will be used during construction was designed using the 2-year storm event since construction will not occur over a long time-frame (approximately one year). The detention vault was designed using WWHM. The live storage detention volume was designed by matching pre and post construction flows and durations for 50 3