HomeMy WebLinkAboutAppendix C - Pond and Pipe Calculations
APPENDIX C
POND SIZING AND STORM SEWER
FACILITIES CALCULATIONS
RETENTION POND #1
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 1A 0.20 1626 325
Hardscape 1A 0.95 0 0
Landscape 1B 0.20 205 41
Hardscape 1B 0.95 5732 5445
Total 7562 5811
C=Weighted C Factor 0.77
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.77
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.17
Q = runoff (cfs) 0.05
V = REQUIRED VOL (ft3)394
Pond Storage Volume (ft3)403
CHASE 1 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 1A 0.20 1626 325
Hardscape 1A 0.95 0 0
Landscape 1B 0.20 205 41
Hardscape 1B 0.95 5732 5445
Total 7562 5811
A = Area (acres) 0.17
C = Weighted C Factor 0.77
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.08 (DA #1B)
i = rainfall intensity (in./hr.) 3.83
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.77 (calculated above)
i = rainfall intensity (in./hr.) 3.83 (calculated above)
A = Area (acres) 0.17 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 0.51
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Chase #1
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 0
Mannings Formula z (sideslope)= 0
w (btm width, ft)= 1
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.015
A = cross sectional area n low =0.013
P= wetted perimeter n high =0.013
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 0.50 2.00 0.25 5.56 2.78 5.56 2.78 T = 1.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
RETENTION POND #2
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 2A 0.20 2909 582
Hardscape 2A 0.95 326 310
Landscape 2B 0.20 4218.70 843.74
Hardscape 2B 0.95 8631 8200
Total 16085 9935
C=Weighted C Factor 0.62
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.62
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.37
Q = runoff (cfs) 0.09
V = REQUIRED VOL (ft3)673
Pond Storage Volume (ft3)843
CHASE 2 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 2A 0.20 2909 582
Hardscape 2A 0.95 326 310
Landscape 2B 0.20 4219 844
Hardscape 2B 0.95 8631 8200
Total 16085 9935
A = Area (acres) 0.37
C = Weighted C Factor 0.62
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.08 (DA #2B)
i = rainfall intensity (in./hr.) 3.83
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.62 (calculated above)
i = rainfall intensity (in./hr.) 3.83 (calculated above)
A = Area (acres) 0.37 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 0.87
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Chase #2
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 0
Mannings Formula z (sideslope)= 0
w (btm width, ft)= 1
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.015
A = cross sectional area n low =0.013
P= wetted perimeter n high =0.013
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 0.50 2.00 0.25 5.56 2.78 5.56 2.78 T = 1.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
RETENTION POND #3
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 3A 0.20 7828 1566
Hardscape 3A 0.95 3611 3430
Total 11439 4996
C=Weighted C Factor 0.44
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.44
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.26
Q = runoff (cfs) 0.05
V = REQUIRED VOL (ft3)339
Pond Storage Volume (ft3)463
RETENTION POND #4
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft2 )C * Area
Landscape 4A 0.20 10588 2118
Hardscape 4A 0.95 12393 11773
Landscape 4A 0.20 1951 390
Hardscape 4A 0.95 18541 17614
Total 43474 31895
C=Weighted C Factor 0.73
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.73
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 1.00
Q = runoff (cfs) 0.30
V = REQUIRED VOL (ft3)2162
Pond Storage Volume (ft3)2,487
CHASE 4A 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 4A 0.20 10588 2118
Hardscape 4A 0.95 12393 11773
Landscape 4B 0.20 1951 390
Hardscape 4B 0.95 18541 17614
Total 43474 31895
A = Area (acres) 1.00
C = Weighted C Factor 0.73
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.08 (DA #4A)
i = rainfall intensity (in./hr.) 3.83
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.73 (calculated above)
i = rainfall intensity (in./hr.) 3.83 (calculated above)
A = Area (acres) 1.00 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 2.80
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Chase #4A
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 0
Mannings Formula z (sideslope)= 0
w (btm width, ft)= 1.5
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.015
A = cross sectional area n low =0.013
P= wetted perimeter n high =0.013
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 0.75 2.50 0.30 6.27 4.71 6.27 4.71 T = 1.50
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Swale #4A
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 4
Mannings Formula z (sideslope)= 4
w (btm width, ft)= 0
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.75
R = A/P S (slope, ft/ft) 0.08
A = cross sectional area n low =0.035
P= wetted perimeter n high =0.035
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.75 2.25 6.18 0.36 6.12 13.77 6.12 13.77 T = 6.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
CHASE 4B 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 4B 0.20 1951 390
Hardscape 4B 0.95 18541 17614
Total 20492 18005
A = Area (acres) 0.47
C = Weighted C Factor 0.88
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.08 (DA #4B)
i = rainfall intensity (in./hr.) 3.83
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.88 (calculated above)
i = rainfall intensity (in./hr.) 3.83 (calculated above)
A = Area (acres) 0.47 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 1.58
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Chase #4B
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 0
Mannings Formula z (sideslope)= 0
w (btm width, ft)= 1
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.015
A = cross sectional area n low =0.013
P= wetted perimeter n high =0.013
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 0.50 2.00 0.25 5.56 2.78 5.56 2.78 T = 1.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
RETENTION POND #5
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor (Post-Development)
Contributing Area DA C Area (ft2 )C * Area
Landscape 5A 0.2 21137 4227
Hardscape 5A 0.95 4815 4574
Landscape 5B 0.2 3690 738
Hardscape 5B 0.95 23405 22235
Total 53046 31774
C=Weighted C Factor 0.60
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.60
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 1.22
Q = runoff (cfs) 0.30
V = REQUIRED VOL (ft3)2153
Pond Storage Volume (ft3)2,259
CHASE 5 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 5A 0.20 21137 4227
Hardscape 5A 0.95 4815 4574
Landscape 5B 0.20 3690 738
Hardscape 5B 0.95 23405 22235
Total 53046 31774
A = Area (acres) 1.22
C = Weighted C Factor 0.60
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.08 (DA #5B)
i = rainfall intensity (in./hr.) 3.83
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.60 (calculated above)
i = rainfall intensity (in./hr.) 3.83 (calculated above)
A = Area (acres) 1.22 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 2.79
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Chase #5
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 0
Mannings Formula z (sideslope)= 0
w (btm width, ft)= 1
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.015
A = cross sectional area n low =0.013
P= wetted perimeter n high =0.013
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 0.50 2.00 0.25 5.56 2.78 5.56 2.78 T = 1.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Swale #5
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 4
Mannings Formula z (sideslope)= 4
w (btm width, ft)= 0
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.025
A = cross sectional area n low =0.035
P= wetted perimeter n high =0.035
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 1.00 4.12 0.24 2.61 2.61 2.61 2.61 T = 4.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
RETENTION POND #6
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 6A 0.20 15808 3162
Hardscape 6A 0.95 2337 2220
Landscape 6B 0.20 3195 639
Hardscape 6B 0.95 19422 18451
Total 40761 24471
C=Weighted C Factor 0.60
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.60
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.94
Q = runoff (cfs) 0.23
V = REQUIRED VOL (ft3)1658
Pond Storage Volume (ft3)1,939
CHASE 6 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 6A 0.20 15808 3162
Hardscape 6A 0.95 2337 2220
Landscape 6B 0.20 3195 639
Hardscape 6B 0.95 19422 18451
Total 40761 24471
A = Area (acres) 0.94
C = Weighted C Factor 0.60
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.08 (DA #5B)
i = rainfall intensity (in./hr.) 3.83
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.60 (calculated above)
i = rainfall intensity (in./hr.) 3.83 (calculated above)
A = Area (acres) 0.94 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 2.15
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Chase #6
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 0
Mannings Formula z (sideslope)= 0
w (btm width, ft)= 1
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.015
A = cross sectional area n low =0.013
P= wetted perimeter n high =0.013
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 0.50 2.00 0.25 5.56 2.78 5.56 2.78 T = 1.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
RETENTION POND #7
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft2 )C * Area
Hardscape 7A 0.95 3611 3430
Landscape 7A 0.2 11719 2344
Hardscape 7B 0.95 19357 18389
Landscape 7B 0.2 3609 722
Hardscape 7C 0.95 2305 2190
Landscape 7C 0.2 594 119
Total 38295 24885
C=Weighted C Factor 0.65
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.65
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.88
Q = runoff (cfs) 0.23
V = REQUIRED VOL (ft3)1686
Pond Storage Volume (ft3)2,079
CHASE 7 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Hardscape 7A 0.95 3611 3430
Landscape 7A 0.2 11719 2344
Hardscape 7B 0.95 19357 18389
Landscape 7B 0.2 3609 722
Hardscape 7C 0.95 2305 2190
Landscape 7C 0.2 594 119
Total 38295 24885
A = Area (acres) 0.88
C = Weighted C Factor 0.65
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.08 (DA #7B)
i = rainfall intensity (in./hr.) 3.83
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.65 (calculated above)
i = rainfall intensity (in./hr.) 3.83 (calculated above)
A = Area (acres) 0.88 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 2.19
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Chase #7
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 0
Mannings Formula z (sideslope)= 0
w (btm width, ft)= 1
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.015
A = cross sectional area n low =0.013
P= wetted perimeter n high =0.013
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 0.50 2.00 0.25 5.56 2.78 5.56 2.78 T = 1.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Swale #7
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 4
Mannings Formula z (sideslope)= 4
w (btm width, ft)= 0.5
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.0097
A = cross sectional area n low =0.035
P= wetted perimeter n high =0.035
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 1.25 4.62 0.27 1.75 2.19 1.75 2.19 T = 4.50
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
RETENTION POND #8
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 8A 0.20 6301 1260
Hardscape 8A 0.95 3611 3430
Landscape 8B 0.20 1769 354
Hardscape 8B 0.95 4123 3917
Total 15804 8961
C=Weighted C Factor 0.57
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.57
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.36
Q = runoff (cfs) 0.08
V = REQUIRED VOL (ft3)607
Pond Storage Volume (ft3)639
CHASE 8 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
Landscape 8A 0.2 6301 1260
Hardscape 8A 0.95 3611 3430
Landscape 8B 0.2 1769 354
Hardscape 8B 0.95 4123 3917
Total 15804 8961
A = Area (acres) 0.36
C = Weighted C Factor 0.57
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.34 (DA #8A)
i = rainfall intensity (in./hr.) 1.57
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.57 (calculated above)
i = rainfall intensity (in./hr.) 1.57 (calculated above)
A = Area (acres) 0.36 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 0.32
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Chase #8
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 0
Mannings Formula z (sideslope)= 0
w (btm width, ft)= 1
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.015
A = cross sectional area n low =0.013
P= wetted perimeter n high =0.013
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 0.50 2.00 0.25 5.56 2.78 5.56 2.78 T = 1.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
RETENTION POND #9
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
LANDSCAPE 9A 0.20 9760 1952
HARDSCAPE 9A 0.95 2407 2287
LANDSCAPE 9B 0.20 6609 1322
HARDSCAPE 9B 0.95 24215 23004
Total 42991 28565
C=Weighted C Factor 0.66
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.66
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.99
Q = runoff (cfs) 0.27
V = REQUIRED VOL (ft3)1936
Pond Storage Volume (ft3)2,111
CHASE 9 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
LANDSCAPE 9A 0.2 9760 1952
HARDSCAPE 9A 0.95 2407 2287
LANDSCAPE 9B 0.2 6609 1322
HARDSCAPE 9B 0.95 24215 23004
Total 42991 28565
A = Area (acres) 0.99
C = Weighted C Factor 0.66
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.08 (DA #9B)
i = rainfall intensity (in./hr.) 3.83
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.66 (calculated above)
i = rainfall intensity (in./hr.) 3.83 (calculated above)
A = Area (acres) 0.99 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 2.51
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Chase #9
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 0
Mannings Formula z (sideslope)= 0
w (btm width, ft)= 1
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.015
A = cross sectional area n low =0.013
P= wetted perimeter n high =0.013
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 0.50 2.00 0.25 5.56 2.78 5.56 2.78 T = 1.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Swale #9
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 4
Mannings Formula z (sideslope)= 4
w (btm width, ft)= 0
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.75
R = A/P S (slope, ft/ft) 0.005
A = cross sectional area n low =0.035
P= wetted perimeter n high =0.035
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.75 2.25 6.18 0.36 1.53 3.44 1.53 3.44 T = 6.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
RETENTION POND #10
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
LANDSCAPE 10A 0.20 2602 520
HARDSCAPE 10A 0.95 15287 14522
LANDSCAPE 10B 0.20 16010 3202
HARDSCAPE 10B 0.95 2407 2287
Total 36306 20532
C=Weighted C Factor 0.57
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.57
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.83
Q = runoff (cfs) 0.19
V = REQUIRED VOL (ft3)1391
Pond Storage Volume (ft3)1,532
CHASE 10 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft 2 )C * Area
LANDSCAPE 10A 0.2 2602 520
HARDSCAPE 10A 0.95 15287 14522
LANDSCAPE 10B 0.2 16010 3202
HARDSCAPE 10B 0.95 2407 2287
Total 36306 20532
A = Area (acres) 0.83
C = Weighted C Factor 0.57
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.08 (DA #10B)
i = rainfall intensity (in./hr.) 3.83
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.57 (calculated above)
i = rainfall intensity (in./hr.) 3.83 (calculated above)
A = Area (acres) 0.83 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 1.80
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Curb #10
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 0
Mannings Formula z (sideslope)= 0
w (btm width, ft)= 1
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.5
R = A/P S (slope, ft/ft) 0.015
A = cross sectional area n low =0.013
P= wetted perimeter n high =0.013
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.5 0.50 2.00 0.25 5.56 2.78 5.56 2.78 T = 1.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
MANNING'S EQUATION for OPEN CHANNEL FLOW Storm Swale #10
Project: Westside Flats Location: Bozeman, MT
By: AMK Date: 5/19/2020
Chk By: Date:
INPUT
z (sideslope)= 4
Mannings Formula z (sideslope)= 4
w (btm width, ft)= 0
Q = (1.486/n)ARh2/3S1/2 d (depth, ft)= 0.75
R = A/P S (slope, ft/ft) 0.0075
A = cross sectional area n low =0.035
P= wetted perimeter n high =0.035
S = slope of channel V = (1.49/n)Rh2/3S1/2
n = Manning's roughness coeffiQ = V x A
Depth, ft Area, sf
Wetted
Perimete
r, ft
Hydraulic
Radius, ft Velocity, fps Flow, cfs
Velocity,
fps Flow, cfs
0.75 2.25 6.18 0.36 1.87 4.22 1.87 4.22 T = 6.00
Low N High N
d
w
z
11
z
T
Clear Data
Entry Cells
RETENTION POND #11
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area DA C Area (ft2 )C * Area
Landscape 11A 0.20 1647 329
Hardscape 11A 0.95 6151 5844
Total 7798 6173
C=Weighted C Factor 0.79
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.79
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.18
Q = runoff (cfs) 0.06
V = REQUIRED VOL (ft3)418
Pond Storage Volume (ft3)593