1605 SE EVERETT MALL WAY BOBS BURGER AND BREW 2025-07-25

Bob's Burger and Brew City of Everett,WA Stormwater Site Plan December 21,2009 flows generated by each basin and the amount of runoff each individual Filterra unit ' can treat. Table 2: Water Quality Flowrates ,-1 ((6) Basin 1 0.056 0.075 93.81% ' Basin 2 0.037 0.075 94.33% Basin 3 0.042 J 0.075 91.2% ' The locations of these units have been shown on Figure 5 in Appendix A. There will be minor onsite runoff, approximately 11,500 sf, from the Top Food's parking lot located to the west of Basin 3. This run-on will flow into the westernmost ' Filterra unit and a portion of this runoff will be treated prior to discharging into the existing drainage facility. The western Filterra unit is oversized to treat an ' additional flow of approximately 0.0326 cfs. Stream Bank Erosions Control BMPs ' To provide stream bank erosion control, PACLAND designed a detention pipe that will be installed onsite to protect any downstream channels from erosion. The ' detention pipe was sized using Stormshed3g which uses the Santa Barbra Urban Hydrograph Method. The detention pipe was designed to release stormwater at 50% of the existing 2-year, 24-hour event and 100% of the existing 10-year and 100-year, 24-hour events. The additional offsite runon from the Top Food's parking lot was included in the ' proposed release rate. The runon area is approximately 0.264 ac and will enter the site at the western Filterra unit. PACLAND treated the existing runon from the Top Food's site as a pass through flow for the orifice sizing. In order to correctly design the orifices on the flow control structure, PACLAND allowed-to- upstream runoff to pass through the orifices ' at 100% of the existing peak runoff rate and matched 50% of the 2-year 24-hour peak flow and 100% of the 10 and 100 year, 24-hour events for the existing on-site runoff rates. The existing runoff rates and proposed release rates that were used to size the orifices on the flow control structure are listed in the table on page 6. The outputs from the Stormshed3g file have been included in Appendix C. I PACLAND Project#30182002 Page 5