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APPENDIX B
DRAINAGE AREA CALULATIONS
DRAINAGE AREA # 1A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 1626 325
Hardscape 0.95 0 0
Total 1626 325
A = Area (acres) 0.04
C = Weighted C Factor 0.20
DRAINAGE AREA # 1B
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 205 41
Hardscape 0.95 5732 5445
Total 5937 5486
A = Area (acres) 0.14
C = Weighted C Factor 0.92
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 2.94 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 99 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)1.30
Tc Total = 5.00 (5 mimimum)
DRAINAGE AREA # 2A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 2909 582
Hardscape 0.95 326 310
Total 3235 892
A = Area (acres) 0.07
C = Weighted C Factor 0.28
DRAINAGE AREA # 2B
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 4219 844
Hardscape 0.95 8631 8200
Total 8631 8200
A = Area (acres) 0.20
C = Weighted C Factor 0.95
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 2.44 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 70 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)1.16
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.64%
L = length of gutter (ft) 64
V = mean velocity (ft/s) 2.40
Tc Gutter Flow (minutes) =0.44
Tc Total = 5.00 (5 minimum)
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.95 (calculated above)
I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm)
A = area (acres) 0.20 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 0.72 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0064
Q = PROVIDED GUTTER CAPACITY (cfs) 2.97
DRAINAGE AREA # 3A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 7828 1566
Hardscape 0.95 3611 3430
Total 11439 4996
A = Area (acres) 0.26
C = Weighted C Factor 0.44
DRAINAGE AREA # 4A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 10588 2118
Hardscape 0.95 3612 3431
Total 14200 5549
A = Area (acres) 0.33
C = Weighted C Factor 0.39
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 1.6 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 54 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)1.17
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0100
L = length of gutter (ft) 184
V = mean velocity (ft/s) 3.00
Tc Gutter Flow (minutes) =1.02
Tc Total = 5.00 (5 minimum)
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.39 (calculated above)
I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm)
A = area (acres) 0.33 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 0.49 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0100
Q = PROVIDED GUTTER CAPACITY (cfs) 3.72
DRAINAGE AREA #4B
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 1951 390
Hardscape 0.95 27322 25956
Total 29273 26346
A = Area (acres) 0.67
C = Weighted C Factor 0.90
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 25 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 20 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)0.29
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 5.11 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.20 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 12 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)3.31
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0130
L = length of gutter (ft) 145
V = mean velocity (ft/s) 3.42
Tc Gutter Flow (minutes) =0.71
Tc Total = 5.00 (5 minimum)
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.90 (calculated above)
I = 0.78 Tc-0.64 (in/hr)5.75 (25-yr storm)
A = area (acres) 0.67 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 3.48 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0130
Q = PROVIDED GUTTER CAPACITY (cfs) 4.24
DRAINAGE AREA # 5A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 21137 4227
Hardscape 0.95 4815 4574
Total 25952 8801
A = Area (acres) 0.60
C = Weighted C Factor 0.34
DRAINAGE AREA #5B
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 3690 738
Hardscape 0.95 23405 22235
Total 27095 22973
A = Area (acres) 0.62
C = Weighted C Factor 0.85
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 25 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 19 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)0.28
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 2.3 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 75 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)1.23
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0170
L = length of gutter (ft) 449
V = mean velocity (ft/s) 3.91
Tc Gutter Flow (minutes) =1.91
Tc Total = 5.00 (5 Minimum)
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.85 (calculated above)
I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm)
A = area (acres) 0.62 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 2.02 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0170
Q = PROVIDED GUTTER CAPACITY (cfs) 4.85
DRAINAGE AREA # 6A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 15808 3162
Hardscape 0.95 2337 2220
Total 18145 5381
A = Area (acres) 0.42
C = Weighted C Factor 0.30
DRAINAGE AREA # 6B
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 3195 639
Hardscape 0.95 19422 18451
Total 22617 19090
A = Area (acres) 0.52
C = Weighted C Factor 0.84
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 2.03 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 84 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)1.35
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0150
L = length of gutter (ft) 133
V = mean velocity (ft/s) 3.67
Tc Gutter Flow (minutes) =0.60
Tc Total = 5.00 (5 Minimum)
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.84 (calculated above)
I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm)
A = area (acres) 0.52 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 1.68 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0150
Q = PROVIDED GUTTER CAPACITY (cfs) 4.55
DRAINAGE AREA # 7A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Hardscape 0.95 3611 3430
Landscape 0.2 11719 2344
Total 15330 5774
A = Area (acres) 0.35
C = Weighted C Factor 0.38
DRAINAGE AREA # 7B
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Hardscape 0.95 19357 18389
Landscape 0.2 3609 722
Total 22965 19111
A = Area (acres) 0.53
C = Weighted C Factor 0.83
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 2.3 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 137 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)1.66
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0156
L = length of gutter (ft) 57
V = mean velocity (ft/s) 3.74
Tc Gutter Flow (minutes) =0.25
Tc Total = 5.00 (5 Minimum)
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.83 (calculated above)
I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm)
A = area (acres) 0.53 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 1.68 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0156
Q = PROVIDED GUTTER CAPACITY (cfs) 4.64
DRAINAGE AREA # 7C
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Hardscape 0.95 2305 2190
Landscape 0.2 594 119
Total 2899 2309
A = Area (acres) 0.07
C = Weighted C Factor 0.80
DRAINAGE AREA # 8A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 6301 1260
Hardscape 0.95 3611 3430
Total 9912 4691
A = Area (acres) 0.23
C = Weighted C Factor 0.47
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 1.76 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.29 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 277 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)20.13
Tc Total = 20.13
DRAINAGE AREA # 8B
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
Landscape 0.2 1769 354
Hardscape 0.95 4123 3917
Total 5892 4271
A = Area (acres) 0.14
C = Weighted C Factor 0.72
DRAINAGE AREA # 9A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
LANDSCAPE 0.2 9760 1952
HARDSCAPE 0.95 2407 2287
Total 12167 4239
A = Area (acres) 0.28
C = Weighted C Factor 0.35
DRAINAGE AREA # 9B
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
LANDSCAPE 0.2 6609 1322
HARDSCAPE 0.95 24215 23004
Total 30824 24326
A = Area (acres) 0.71
C = Weighted C Factor 0.79
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 2.4 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 119 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)1.52
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0178
L = length of gutter (ft) 74
V = mean velocity (ft/s) 4.00
Tc Gutter Flow (minutes) =0.31
Tc Total = 5.00 (5 Minimum)
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.79 (calculated above)
I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm)
A = area (acres) 0.71 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 2.14 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0178
Q = PROVIDED GUTTER CAPACITY (cfs) 4.96
DRAINAGE AREA # 10A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
LANDSCAPE 0.2 2602 520
HARDSCAPE 0.95 15287 14522
Total 17888 15043
A = Area (acres) 0.41
C = Weighted C Factor 0.84
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 1.7 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 120 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)1.72
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0100
L = length of gutter (ft) 119
V = mean velocity (ft/s) 3.00
Tc Gutter Flow (minutes) =0.66
Tc Total = 5.00 (5 Minimum)
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.84 (calculated above)
I = 0.78 Tc-0.64 (in/hr)3.83 (25-yr storm)
A = area (acres) 0.41 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 1.32 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (ft/ft) 0.0100
Q = PROVIDED GUTTER CAPACITY (cfs) 3.72
DRAINAGE AREA # 10B
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
LANDSCAPE 0.2 16010 3202
HARDSCAPE 0.95 2407 2287
Total 18418 5489
A = Area (acres) 0.42
C = Weighted C Factor 0.30
DRAINAGE AREA # 11A
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2 )C * Area
LANDSCAPE 0.2 1647 329
HARDSCAPE 0.95 6151 5844
Total 7798 6173
A = Area (acres) 0.18
C = Weighted C Factor 0.79