6307 36TH AVE W 2025-07-29 - Laserfiche WebLink

Intermec I Kenilworth Hills Stormwater Analysis Everett, WA IModeling Process The proposed Intermec Lot 2 Pond was designed per the current city standards. The 25- year, 1-hour storm was then routed through that pond model for this analysis. Although the Lot 2 pond has two outfall structures, the entire site was routed through only the IEdgewater Creek control structure for the purpose of this report. The existing ponds were modeled using as-built information from the City of Everett archives. Basin data was generated both from the project survey and from the original drainage calculations from the Intermec Lot 1 and Kenilworth Hills developments. ISince this analysis is simply routing a storm through the ponds and not actually designing the ponds, the Match Q" has been labeled N/A as no flow is being matched. 111 The following ponds are modeled in this report: (from upstream to downstream) Lot 2 pond— The proposed pond for Intermec — Lot 2. Intermec Pond 1 - Upstream existing Intermec pond. Intermec Pond 2 — Downstream existing Intermec pond. IKenilworth Hills Pond— Existing Kenilworth Hills pond downstream of Intermec. The following steps were taken to model the drainage basin: I1. Model the Lot 2 pond to generate a discharge hydrograph. 2. Shift the Lot 2 discharge hydrograph by 10 minutes to account for travel time from the Lot 2 pond outlet to the confluence with the Intermec Pond 1 discharge. 3. Route the Intermec Pond 1 basin through the pond to generate a discharge hydrograph for the Intermec Pond 1 basin for the 25-yr, 1-hour storm. 4. Generate a runoff hydrograph for the Intermec Pond 2 basin. I 5. Add the shifted Lot 2 discharge hydrograph, the Intermec Pond 1 discharge and the Intermec Pond 2 basin hydrograph to generate the inflow hydrograph for Intermec I Pond 2. 6. Route the hydrograph generated in Step 5 through Intermec Pond 2. 7. Generate a runoff hydrograph for the Kenilworth Hills Pond basin. 8. Add discharge hydrograph generated in Step 6 and the runoff hydrograph for the Kenilworth Hills Pond basin to generate the Kenilworth Hills Pond inflow hydrograph. t9. Route the hydrograph generated in Step 8 through the Kenilworth Hills Pond. For the site to be in compliance with the rezoning ordinance, the peak discharge from the IKenilworth Hills No. 1 pond (Hydrograph #10) must be below 0.5 cfs. As shown on the last page of this analysis, the peak discharge from the Kenilworth Hills IPond during the 25-year, 1-hour storm is 0.20 CFS. Therefore with the development of Intermec Lot 2 utilizing the 1992 DOE Manual for stormwater design, the basin is still in compliance with the rezoning ordinance. PACLAND Jobl# 50175001 Page 9