SW6210205_1644-Runoff coefficient calcs_20210310

Spring Lake Ray Road Dollar General
Storm Water Control
SCS curve number
Hydraulic Soil Group: D
Area SCS CN
Building (sf)
8,990
98
Pavement (sf)
29,839
98
Pond (sf)
6,671
98
Open space (sf)
20,881
80
Offsite -open space (sf)
80
Future -impervious (sf)
2,444
98
Total (sf)
68825
93
Total (ac)
1.58
Rational Coefficient
Predevelopment
Area C
Impervious (st) 0.95
Open space (st) 68,825 0.25
Total (ac) 68825 0.25
Total (ac) 1.58
Postdevelopment
Area
C
Building (st)
8,990
0.95
Pavement (st)
29,839
0.95
Pond (st)
6,671
0.95
Open space (st)
20,881
0.35
Offsite -open space (st)
0.3
Future -impervious (st)
2,444
0.95
Total (ac)
68825
0.77
Total (ac)
1.58
1644-Runoff coefficient calcs.xls Printed 3/10/2021