901 W CASINO RD 2018-01-02 MF Import

DRAINAGE/DETENTION EVALUATION FOR THE PROPOSED ARCO AM/PM MINI -MARKET LOCATED AT 901 WEST CASINO ROAD EVERETT,WASHINGTON The proposed project lies in a portion of the Southwest quarter of Section 12, Township 28 North, Range 4 East of the Willamette Meridian in Everett, Washington (See Vicinity Map, Exhibit A). The subject property is approximately square in shape and encompass- ing slightly over 3/4 of an acre. The site is bounded to the south by West Casino Road. West Casino Road provides approximately 180 feet of frontage along the south property boundary. The abutting properties to the north and west are currently undeveloped, while the property directly to the east is developed as a single-family residential lot. The project site is currently undeveloped with no apparent land use. The existing groundcover consists of various grasses and a sparse variety of evergreen trees. The site is relatively flat with a downward slope of approximately three percent from the southeast property corner to the northwest property corner. The proposed project is to construct a 2,500 square foot single -story wood frame mini- market facility with the retail distribution of gasoline. The building structure shall be located within the northern portion of the subject property and surrounded by ap- propriate parking and landscaping. Since the proposed project will increase the impervious surface area, consequently increasing stormwater runoff, detention will be required. However, the City of Everett has indicated that a local regional detention facility is available. Therefore in lieu of providing on -site detention, payment to the City Drainage Fund 340 is allowed. Payment to this fund is based on $2.51 per cubic foot of required on -site detention storage. Researching various city's records has revealed that the subject property lies within the Merril and Ring Creek Drainage Basin which requires detention design for a 10-year pre -development storm and a 25-year post - development storm. The civil engineering design plans for this project and the boundary and topographic survey shown on these plans have been prepared by the firm of Barghausen Consulting Engineers, Inc. L4120.11 V CE Nffal I UiX42 AL101CKfaW f From a site investigation and referencing the attached tributary maps, it is realized that the subject property lies within an area identified as the Merril and Ring Creek Drainage Basin. This portion of the basin is isolated from off -site stormwater runoff. As previously discussed, the site is bounded to the south by West Casino Road. The curb and gutter provided during the construction of West Casino Road prohibits stormwater runoff to enter onto the subject property from the south. It is obvious that stormwater runoff will not drain onto the subject property from the east, west, or north directions as dictated by topography. Therefore, off -site stormwater contributions are not applicable to the design of the on -site storm drainage system.