6201 ASSOCIATED BLVD BASE FILE 2018-03-29

4 ; Y C I= COI0 In order to achieve the Pre-Mining basin characteristics, 100% of the 200,000 square foot building rooftop area within Phase 1 & 30% of the rooftop area within Phase 2 will connect temporarily to the existing drainage system along Glenwood Ave. The City of Everett has agreed to the temporary connection of the roof drainage to Glenwood Ave with a permanent connection to CEMEX's proposed infiltration gallery at the time of its construction. Runoff will ultimately flow into CEMEX's site and be incorporated into the on-site stormwater management facility. Eventually this area will be tributary to Pigeon Creek when development of CEMEX according to the Planned Development Overlay is complete. All new pollution generating impervious surfacing in the proposed development will be treated with a water quality wetpond prior to connection into the Glenwood regional facility. 2.0 DESIGN CRITERIA AND ASSUMPTIONS 2.1 GOVERNING GUIDELINES The City of Everett(COE)has implemented the Stormwater Management Manual for identifying stormwater management requirements for development inside city limits. This manual is written to be technically equivalent to the 1992 Washington State Department of Ecology stormwater management manual. The proposed water quality and detention stormwater facilities for this project have been designed to meet the requirements of the COE Storrnwater Management Manual in effect at the date of vesting. The proposed project will create more than 5,000 square feet of new impervious surfacing. According to Table 1-1.1 from the COE Manual all stormwater controls and a Stormwater Site Plan and Drainage Plan are required. This report is organized following Minimum Requirements #1 through #10 outlined in the 2005 DOE Manual. These requirements are listed in Section 5, Summary of Minimum Development Requirements, of this Stormwater Site Plan along with a response of how these requirements shall be met. This organizational method meets City of Everett requirements while providing some additional information. 2.2 DESIGN CRITERIA Water quality treatment(wetpond)will be provided according to the 2005 City of Everett Design Manual requirement for all pollution generating surfaces prior to connection into the Glenwood regional facility. Hydrologic analysis was performed using the StormSHED software (formerly Waterworks), using SBUH or SCS TR-55 methods for hydrograph generation. Prior to entering the wetpond drainage will pass through a Vortech pre-treatment vault. All rooftop drainage from Phase 1 and 30% from Phase 2 will not require water quality treatment prior to temporarily connecting to the Glenwood Ave drainage system and ultimately the infiltration system within CEMEX's property as the tributary impervious surfacing is not considered pollution generating. DAVID EVANS AND ASSOCIATES,INC. UNDERWOOD GARTLAND EVERETT FEBRUARY 3,2015 STORMWATER SITE PLAN PAGE 2