10-MM Skimmer Basin Calcs

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-1
Total Acres 1.21 Disturbed acres 0.085
Q = 2 cfs (10 year Storm) Dewater in 2 days
Q = 2.29 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 153 ft3
Minimum Area 650 ft2
Minimum Depth 0.2354 ft
Design Depth 3 ft
Water area footprint = Length 39 ft Width 18 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 1404 ft3 Basin Volume 1620
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.93 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
702 ft3/day
Max outflow rate
3.6465 gpm
2.5905 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-2
Total Acres 0.31 Disturbed acres 0.04
Q = 0.57 cfs (10 year Storm) Dewater in 2 days
Q = 0.66 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 72 ft3
Minimum Area 185.25 ft2
Minimum Depth 0.3887 ft
Design Depth 3 ft
Water area footprint = Length 20 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 400 ft3 Basin Volume 357
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.49 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
200 ft3/day
Max outflow rate
1.0389 gpm
0.7466 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-3
Total Acres 2.28 Disturbed acres 1.02
Q = 5.37 cfs (10 year Storm) Dewater in 2 days
Q = 6.15 cfs (25 year Storm)
Length:W idth Ration = 4.5;1
Minimum Volume 1836 ft3
Minimum Area 1745.3 ft2
Minimum Depth 1.052 ft
Design Depth 3 ft
Water area footprint = Length 90 ft Width 20 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 3600 ft3 Basin Volume 4437
Desired skimmer flow rate in ft3/day = 1800 ft3/day
Skimmer size from chart 2 inches Max outflow rate 3283 ft3/day
Calculated Orifice size 1.38 inches
Average outflow rate from skimmer = 9.35 gpm
Calculated Width of Emergency Spillway 6.957 ft
Spacing between porus baffles 22.5 ft

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-3A
Total Acres 0.3 Disturbed acres 0.044
Q = 0.58 cfs (10 year Storm) Dewater in 2 days
Q = 0.66 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 79.2 ft3
Minimum Area 188.5 ft2
Minimum Depth 0.4202 ft
Design Depth 3 ft
Water area footprint = Length 20 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 400 ft3 Basin Volume 357
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.49 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
200 ft3/day
Max outflow rate
1.0389 gpm
0.7466 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-4
Total Acres 0.38 Disturbed acres 0.069
Q = 0.77 cfs (10 year Storm) Dewater in 2 days
Q = 0.89 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 124.2 ft3
Minimum Area 250.25 ft2
Minimum Depth 0.4963 ft
Design Depth 3 ft
Water area footprint = Length 26 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 520 ft3 Basin Volume 483
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.56 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
260 ft3/day
Max outflow rate
1.3506 gpm
1.0068 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-5
Total Acres 0.37 Disturbed acres 0.07
Q = 0.77 cfs (10 year Storm) Dewater in 2 days
Q = 0.89 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 0 ft3
Minimum Area 250.25 ft2
Minimum Depth 0 ft
Design Depth 3 ft
Water area footprint = Length 26 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 520 ft3 Basin Volume 483
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.56 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
260 ft3/day
Max outflow rate
1.3506 gpm
1.0068 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-6
Total Acres 0.55 Disturbed acres 0.028
Q = 0.87 cfs (10 year Storm) Dewater in 2 days
Q = 0.99 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 50.4 ft3
Minimum Area 282.75 ft2
Minimum Depth 0.1782 ft
Design Depth 3 ft
Water area footprint = Length 29 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 580 ft3 Basin Volume 546
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.59 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
290 ft3/day
Max outflow rate
1.5064 gpm
1.1199 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-7
Total Acres 0.23 Disturbed acres 0.1
Q = 0.57 cfs (10 year Storm) Dewater in 2 days
Q = 0.65 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 180 ft3
Minimum Area 185.25 ft2
Minimum Depth 0.9717 ft
Design Depth 3 ft
Water area footprint = Length 20 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 400 ft3 Basin Volume 357
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.49 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
200 ft3/day
Max outflow rate
1.0389 gpm
0.7353 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-8
Total Acres 0.62 Disturbed acres 0.078
Q = 1.14 cfs (10 year Storm) Dewater in 2 days
Q = 1.32 cfs (25 year Storm)
Length:W idth Ration = 3;1
Minimum Volume 140.4 ft3
Minimum Area 370.5 ft2
Minimum Depth 0.3789 ft
Design Depth 3 ft
Water area footprint = Length 38 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 760 ft3 Basin Volume 735
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.68 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
380 ft3/day
Max outflow rate
1.9739 gpm
1.4876 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-9
Total Acres 0.57 Disturbed acres 0.03
Q = 0.86 cfs (10 year Storm) Dewater in 2 days
Q = 0.99 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 54 ft3
Minimum Area 279.5 ft2
Minimum Depth 0.1932 ft
Design Depth 3 ft
Water area footprint = Length 28 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 560 ft3 Basin Volume 525
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.58 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
280 ft3/day
Max outflow rate
1.4544 gpm
1.1199 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-10
Total Acres 0.43 Disturbed acres 0.25
Q = 1.11 cfs (10 year Storm) Dewater in 2 days
Q = 1.27 cfs (25 year Storm)
Length:W idth Ration = 3;1
Minimum Volume 450 ft3
Minimum Area 360.43 ft2
Minimum Depth 1.2485 ft
Design Depth 3 ft
Water area footprint = Length 37 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 740 ft3 Basin Volume 714
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.67 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
370 ft3/day
Max outflow rate
1.9219 gpm
1.4367 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-11
Total Acres 0.32 Disturbed acres 0.073
Q = 0.71 cfs (10 year Storm) Dewater in 2 days
Q = 0.82 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 131.4 ft3
Minimum Area 230.75 ft2
Minimum Depth 0.5694 ft
Design Depth 3 ft
Water area footprint = Length 24 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 480 ft3 Basin Volume 441
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.54 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
240 ft3/day
Max outflow rate
1.2467 gpm
0.9242 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-12
Total Acres 0.36 Disturbed acres 0.085
Q = 0.81 cfs (10 year Storm) Dewater in 2 days
Q = 0.93 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 153 ft3
Minimum Area 262.6 ft2
Minimum Depth 0.5826 ft
Design Depth 3 ft
Water area footprint = Length 27 ft Width 10 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 540 ft3 Basin Volume 504
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.57 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
270 ft3/day
Max outflow rate
1.4025 gpm
1.0475 ft
1728 ft3/day

Skimmer Basin Design and Calculation sheet Basin No. MM-SB-13
Total Acres 0.17 Disturbed acres 0.05
Q = 0.42 cfs (10 year Storm) Dewater in 2 days
Q = 0.48 cfs (25 year Storm)
Length:W idth Ration = 2;1
Minimum Volume 90 ft3
Minimum Area 135.2 ft2
Minimum Depth 0.6657 ft
Design Depth 3 ft
Water area footprint = Length 20 ft Width 7 ft
Width = square root of area(Min or adj) / L:W Ratio Adjusted area = (Min. vol.ft3/design dept ft)
Volume of top 2 feet 280 ft3 Basin Volume 204
Desired skimmer flow rate in ft3/day =
Skimmer size from chart 1.5 inches
Calculated Orifice size 0.41 inches
Average outflow rate from skimmer =
Barrel Diameter 4 inches
Calculated Width of Emergency Spillway
Spacing between porus baffles
140 ft3/day
Max outflow rate
0.7272 gpm
0.5396 ft
1728 ft3/day