10611 EVERGREEN WAY KLEIN HONDA 2022-10-27

• 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 Klein Honda located at 10611 Evergreen Way, Everett WA. More generally the projects located in The proposed project Klein Honda is located at 10611 Evergreen Way, Everett WA 98204. More generally, the sites located in Section 24, Township 24 North, and Range 4 East of the Willamette Meridian in the City of Everett, Washington.The site is currently developed with a car dealership with associated parking and exists as nearly 100% impervious. The site is relatively flat and gently slopes toward the southwest corner of the property. Per NRCS survey of Snohomish County, the project site contains Alderwood Urban Land Complex 2 to 8 percent soils that have a hydrologic classification of Type "C". The site area is 3.19 Acres. The proposal includes an extension to the current building with additional parking. The total disturbed area will be 0.5 acres with a total hard surface replacement quantity of 0.5 acres (21,760 SF). No new impervious areas are proposed. Minimum requirements 1-5 apply to the project as the proposal involves replacement of impervious surface. Refer to the Flowchart for Determining Requirements for Redevelopment attached in the next page. For onsite stormwater management (MR#5) full dispersion was considered first however it was deemed infeasible due to the lack of native vegetation. Downspout full infiltration was deemed infeasible due to the soils poor infiltration qualities. Bioretention was deemed infeasible due to the soils poor infiltration. Downspout dispersion system was deemed infeasible due to a lack of vegetative flow path. Perforated stub out connection was considered and deemed feasible. Onsite stormwater management for the roof area will be provided by perforated stub out connections. The overflow from the perforated stub out connection will be connected to the existing drainage system onsite that drains to the south within a closed pipe system. For other hard surfaces full dispersion was considered infeasible due to the lack of vegetation, permeable pavement and bioretention were deemed infeasible due to the soils poor infiltration. Sheet flow dispersion was deemed feasible and will be used. Pervious areas had no feasible BMPs due to the site being nearly 100% impervious. Insight Engineering Co. -Stormwater Site Plan 11/16/17 - 13 -