31 SW EVERETT MALL WAY 2018-01-02 MF Import

DRAINAGE STUDY Labco Auto Body Repair Facility City of Everett, Washington INTRODUCTION This report addresses storm drainage issues associated with development of the property to comply with The ',ity of Everett Drainage Ordinance No. 670-80. The Labco Auto Body site is located within Section 24, Township 28 North, Range 4 East, Willamette Meridian, in the North Creek drainage basin, City of Everett, Washington, see Figure 1. The site has been Geared, stripped of vegetation, and filled with two to three feet of compacted soil. The northerly 20 to 30 feet of the property supports a low depression area that historically served as a conveyance way for storm water runoff from the site. This area is heavily vegetated and shows no sign of erosion. To the north, the site is bounded by a lot supporting a single-family resident, Everett Mall Way to the south, 1st Place West to the west and a wetland/drainage course to the east. The site is comprised of 0.6+/- acres. Of the 0.60 acres, approximately 0.50 acres will be altered by this proposal. The remaining 0.10 acres will remain as protected wetland or as a wetland buffer. The existing topography is relatively flat with minor changes in elevation. The site drains in the southerly direction to Everett Mall Way. The site's runoff is then conveyed by closed conduit west down Everett Mall Way. Due to the site's elevation relative to surrounding properties and streets, no off -site stone water drainage onto the property is anticipated. Soils NINE "I"19P The soil on the project site are classified in the Soil Survey of Snohomish County Area, Washington as Alderwood-Urban Land Complex. The Alderwood soil is typically characterized by a gravelly sandy loam for the upper 7 inches. The subsoil is generally a very sandy loam for about 27-35 inches, overlaying a weakly cemented hardpan. The Jepth of the hard pan ranges from 20 to 40 inches. The permeability of the Alderwood soil is moderately rapid above the hardpan. Runoff is slow, and the hazard of water erosion is slight. The Alderwood soil is classified as a hydraulic soil group "C". See Figure 2 and Table 1 for a map showing the soil type in the project vicinity and an index to soil map units. PROPOSED CONDITIONS The proposed project includes constructing an auto body repair facility approximately 5800 square feet in size, supporting parking facilities and landscaping along the east side of the property. Parking lot landscaping will be provided in islands within paved areas. Access to the site will be provided off 1st Place West. Minor curb modifications will be necessary for an approach. nRMMPAPS