JMA02P003 262 270 Main Street Development Stormwater Management Report

Proposed Flows NOAA10 24-hr D 10-Year-Current Rainfall=5.33" Prepared by HydroCAD SAMPLER 1-800-927-7246 www.hydrocad.net Printed 5/26/2026 HydroCAD® 10.20-8a Sampler s/n S05110 © 2025 HydroCAD Software Solutions LLC This report was prepared with the free HydroCAD SAMPLER, which is licensed for evaluation and educational use ONLY. For actual design or modeling applications you MUST use a full version of HydroCAD which may be purchased at www.hydrocad.net. Full programs also include complete technical support,training materials, and additional features which are essential for actual design work. Summary for Pond 2P: Basin A Inflow Area = 13,934 sf,100.00% Impervious, Inflow Depth = 5.09" for 10-Year-Current event Inflow = 1.95 cfs @ 12.06 hrs, Volume= 5,913 cf Outflow = 0.36 cfs @ 12.26 hrs, Volume= 5,913 cf, Atten= 81%, Lag= 12.0 min Discarded = 0.02 cfs @ 3.45 hrs, Volume= 3,179 cf Primary = 0.34 cfs @ 12.26 hrs, Volume= 2,735 cf Routed to nonexistent node 6L Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 97.42' @ 12.26 hrs Surf.Area= 2,143 sf Storage= 2,470 cf Plug-Flow detention time= 310.1 min calculated for 5,909 cf (100% of inflow) Center-of-Mass det. time= 310.5 min ( 1,055.2 - 744.8 ) Volume Invert Avail.Storage Storage Description #1A 95.70' 1,544 cf 29.50'W x 72.63'L x 2.71'H Field A 5,803 cf Overall - 1,943 cf Embedded = 3,859 cf x 40.0% Voids #2A 96.20' 1,943 cf Cultec R-180HD x 88 Inside #1 Effective Size= 33.6"W x 20.0"H => 3.44 sf x 6.33'L = 21.8 cf Overall Size= 36.0"W x 20.5"H x 7.33'L with 1.00' Overlap Row Length Adjustment= +1.00' x 3.44 sf x 8 rows 3,487 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary 96.60' 2.5" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Primary 97.35' 4.0' long x 0.5' breadth Broad-Crested Rectangular Weir

96.60' 2.5" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #2 Primary 97.35' 4.0' 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 Discarded 95.70' 0.500 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.02 cfs @ 3.45 hrs HW=95.73' (Free Discharge) 3=Exfiltration (Exfiltration Controls 0.02 cfs) Primary OutFlow Max=0.33 cfs @ 12.26 hrs HW=97.42' (Free Discharge) 1=Orifice/Grate (Orifice Controls 0.14 cfs @ 4.06 fps) 2=Broad-Crested Rectangular Weir (Weir Controls 0.19 cfs @ 0.72 fps)