9212 HOLLY DR 2018-01-02 MF Import

H H H I H 0 1 I 1 1 1 1 r L Page 9 of 29 III. Analysis and Design of Required Erosion and Sediment Control Erosion control measures are based upon the City of Everett Stormwater Manual, Chapter 2 "Erosion and Sediment Control Best Management Practices". The BMP's proposed are, but not limited to: BMP El.15 — Mulching and Matting BMP E2.10 — Stabilized Construction Entrance BMP E2.20 — Dust Control BMP E2.55 — Interceptor Dike and Swale BMP E2.60 — Check Dams BMP E3.10 — Filter Fence BMP E3.15 — Straw Bale Barrier BMP E3.30 — Storm Drain Inlet Protection BMP E3.40—Temporary Sedimentation Pond Temporary Sedimentation Pond Sizing The Sediment Pond was sized based on the guidelines outlined in the City's Stormwater Management Manual page 2-5-4. This requires a water surface of 1250 square -feet per cubic feet of runoff for the 10-year peak discharge from the site. The 10-year discharge was determined to be 1.14 cfs (see W WMH2 printout in the Appendix). Flow Frequency Return Periods for Developed Mitigated Return Period Flow(cfs) 2 year 0.650203 5 year 0.935714 10 year 1.145537 25 year 1.434644 50 year 1.667723 100 year 1.916248 Therefore the water surface should be: 1.14 x 12:)0 = 1425 sf The pond shown on the plans is 25' x 58' which is 1450 sf, this is adequate size. The outfall for the pond will be a pipe connected to the existing CB at the south-east comer of the site.