2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48" Prepared by Dynamic Engineering Printed 2/10/2026 HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 99
Summary for Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
Runoff = 0.02 cfs @ 12.22 hrs, Volume= 0.003 af, Depth= 1.83" Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.020 39 >75% Grass cover, Good, HSG A
0.020 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 8 0.0125 0.10 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
0.2 46 0.0380 3.96 Shallow Concentrated Flow, B-C Paved Kv= 20.3 fps
1.3 297 0.0035 3.68 4.52 Pipe Channel, C-D 15.0" Round Area= 1.2 sf Perm= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
2.9 351 Total, Increased to minimum Tc = 10.0 min
Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
2026-02 Existing and ProposedNOAA 24-hr D100-Year-CurrentRainfall=9.48''
Prepared by Dynamic EngineeringPrinted2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640© 2025 HydroCAD Software Solutions LLCPage 100
Summary for Subcatchment 12S: Study Area Road Undetained (Imp)
Runoff = 0.18 cfs @ 12.19 hrs, Volume= 0.023 af, Depth= 9.24" Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
0.4 35 0.0322 1.52
Sheet Flow, A-B
Smooth surfaces n= 0.011 P2= 4.04"
0.4 35 Total Increased to minimum Tc = 10.0 min
0.4 35 Total, Increased to minimum Tc = 10.0 min
Subcatchment 12S: Study Area Road Undetained (Imp)