Text · page 30 of 65
Read the whole document on one page (all 65 pages, each with its own heading)
25-4181 storm calcs - existing Type II 24-hr 100-Year Rainfall=5.23" Prepared by Carmina Wood Design Printed 2/11/2026 HydroCAD® 10.20-8a s/n 05019 © 2025 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment 1S: Existing Site Runoff = 6.75 cfs @ 12.05 hrs, Volume= 20,044 cf, Depth= 4.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.50-70.02 hrs, dt= 0.04 hrs Type II 24-hr 100-Year Rainfall=5.23" Area (sf) CN Description 8,670 98 Roofs, HSG D 31,405 98 Paved parking, HSG D 12,963 80 >75% Grass cover, Good, HSG D 53,038 94 Weighted Average 12,963 24.44% Pervious Area 40,075 75.56% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.1 94 0.0250 0.11 Sheet Flow, Grass: Dense n= 0.240 P2= 2.50" Subcatchment 1S: Existing Site Hydrograph Runoff 6.75 cfs 7 Type II 24-hr 6 100-Year Rainfall=5.23" Runoff Area=53,038 sf 5 Runoff Volume=20,044 cf Flow (cfs) 4 Runoff Depth=4.54" Flow Length=94' 3 Slope=0.0250 '/' 2 Tc=14.1 min CN=94 1 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 Time (hours) Page 30 of 65