250701_42 ERW_Stormwater Report

NOAA 24-hr D 2-Year Rainfall=3.44" 250624_42 ERW Waymaker Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 7/1/2025 Page 13 Summary for Pond BASIN: Inflow Area = 2.619 ac, 32.35% Impervious, Inflow Depth = 2.07" for 2-Year event Inflow = 5.32 cfs @ 12.09 hrs, Volume= 0.451 af Outflow = 1.65 cfs @ 12.36 hrs, Volume= 0.451 af, Atten= 69%, Lag= 16.4 min Discarded = 0.60 cfs @ 12.37 hrs, Volume= 0.355 af Primary = 1.05 cfs @ 12.36 hrs, Volume= 0.096 af Routed to Reach DP1-PR : Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 16.66' @ 12.37 hrs Surf.Area= 0.108 ac Storage= 0.115 af Plug-Flow detention time= 39.5 min calculated for 0.450 af (100% of inflow) Center-of-Mass det. time= 39.5 min ( 842.9 - 803.4 ) Volume #1A Invert 15.00' Avail.Storage 0.129 af #2A 15.75' 0.216 af 0.345 af Storage Description 44.25'W x 106.08'L x 5.00'H Field A 0.539 af Overall - 0.216 af Embedded = 0.323 af x 40.0% Voids ADS_StormTech MC-3500 d +Cap x 84 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 84 Chambers in 6 Rows Cap Storage= 14.9 cf x 2 x 6 rows = 178.8 cf Total Available Storage Storage Group A created with Chamber Wizard Device #1 Routing Primary Invert 15.96' #2 Primary 16.55' #3 Primary 18.90' #4 Discarded 15.00' Outlet Devices 3.5" Vert. Orifice/Grate X 4.00 C= 0.600 Limited to weir flow at low heads 5.0" Vert. Orifice/Grate X 3.00 C= 0.600 Limited to weir flow at low heads 1.0' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 3.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 13.00' Discarded OutFlow Max=0.60 cfs @ 12.37 hrs HW=16.66' (Free Discharge) 4=Exfiltration ( Controls 0.60 cfs) Primary OutFlow Max=1.05 cfs @ 12.36 hrs HW=16.66' (Free Discharge) 1=Orifice/Grate (Orifice Controls 0.96 cfs @ 3.58 fps) 2=Orifice/Grate (Orifice Controls 0.09 cfs @ 1.12 fps) 3=Broad-Crested Rectangular Weir ( Controls 0.00 cfs)