251203_42 ERW_Stormwater Report

251202_42 ERW Waystone - Future Rainfall NOAA 24-hr D 2-Year Rainfall=4.09" Prepared by Colliers Engineering & Design HydroCAD® 10.20-5c s/n 04431 © 2023 HydroCAD Software Solutions LLC Printed 12/3/2025 Page 20 Pond BASIN: - Chamber Wizard Field A Chamber Model = ADS_StormTechMC-3500 d +Cap (ADS StormTech® MC-3500 d rev 03/14 with Cap volume) 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 Cap Storage= 14.9 cf x 2 x 7 rows = 208.6 cf 77.0" Wide + 9.0" Spacing = 86.0" C-C Row Spacing 19 Chambers/Row x 7.17' Long +1.85' Cap Length x 2 = 139.93' Row Length +12.0" End Stone x 2 = 141.93' Base Length 7 Rows x 77.0" Wide + 9.0" Spacing x 6 + 12.0" Side Stone x 2 = 51.42' Base Width 9.0" Stone Base + 45.0" Chamber Height + 6.0" Stone Cover = 5.00' Field Height 133 Chambers x 110.0 cf + 14.9 cf Cap Volume x 2 x 7 Rows = 14,832.2 cf Chamber Storage 36,487.8 cf Field - 14,832.2 cf Chambers = 21,655.6 cf Stone x 40.0% Voids = 8,662.3 cf Stone Storage Chamber Storage + Stone Storage = 23,494.5 cf = 0.539 af Overall Storage Efficiency = 64.4% Overall System Size = 141.93' x 51.42' x 5.00' 133 Chambers 1,351.4 cy Field 802.1 cy Stone