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WEST SENECA - POST DEVELOPMENT E_App E_Post-Development Model_REV 2 NY-West Seneca 24-hr S1 1-yr Rainfall=1.82" Prepared by Labella Associates Printed 7/26/2026 HydroCAD® 10.20-6a s/n 09581 © 2024 HydroCAD Software Solutions LLC Page 32 Summary for Pond CH-1: Chambers Inflow Area = 2.286 ac, 90.30% Impervious, Inflow Depth = 1.45" for 1-yr event Inflow = 5.27 cfs @ 12.04 hrs, Volume= 0.276 af Outflow = 0.38 cfs @ 12.72 hrs, Volume= 0.229 af, Atten= 93%, Lag= 41.0 min Primary = 0.38 cfs @ 12.72 hrs, Volume= 0.229 af Routed to Reach DP-1 : Design Point Routing by Dyn-Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs Peak Elev= 592.21' @ 12.72 hrs Surf.Area= 6,598 sf Storage= 7,377 cf Flood Elev= 598.32' Surf.Area= 13,198 sf Storage= 26,499 cf Plug-Flow detention time= 341.3 min calculated for 0.229 af (83% of inflow) Center-of-Mass det. time= 269.3 min ( 1,055.1 - 785.8 ) Volume Invert Avail.Storage Storage Description #1A 590.50' 9,166 cf 44.25'W x 149.10'L x 5.50'H Field A 36,287 cf Overall - 13,373 cf Embedded = 22,914 cf x 40.0% Voids #2A 591.25' 13,373 cf ADS_StormTech MC-3500 d +Cap x 120 Inside #1 Effective Size= 70.4"W x 45.0"H => 15.33 sf x 7.17'L = 110.0 cf Overall Size= 77.0"W x 45.0"H x 7.50'L with 0.33' Overlap 120 Chambers in 6 Rows Cap Storage= 14.9 cf x 2 x 6 rows = 178.8 cf #3 596.00' 3,960 cf Custom Stage Data (Prismatic)Listed below (Recalc) 26,499 cf Total Available Storage Storage Group A created with Chamber Wizard Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 596.00 6,600 0.0 0 0 597.50 6,600 40.0 3,960 3,960 Device Routing Invert Outlet Devices #1 Primary 590.50' 8.0" Round Culvert L= 120.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 590.50' / 589.25' S= 0.0104 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf #2 Device 1 591.25' 4.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 594.35' 4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=0.38 cfs @ 12.72 hrs HW=592.21' TW=0.00' (Dynamic Tailwater) 1=Culvert (Passes 0.38 cfs of 1.47 cfs potential flow) 2=Orifice/Grate (Orifice Controls 0.38 cfs @ 4.30 fps) 3=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) Page 499 of 1174