Vegetated Filter Strip System Design Manual
Design Guidelines of VFS System Components

Orifice
Diameter
(in) 		Orifice
Area
(ft2) 		Discharge Capacity at Specific Head (m)
2
(gal/min.) 		2.1
(gal/min.) 		2.2
(gal/min.) 		2.3
(gal/min.) 		2.4
(gal/min.) 		2.5
(gal/min.)
0.39 0.00 6.95 7.12 7.28 7.45 7.61 7.77
0.79 0.00 27.78 28.47 29.14 29.79 30.44 31.06
1.18 0.01 62.51 64.06 65.56 67.04 68.48 69.89
1.57 0.01 111.13 113.88 116.56 119.18 121.74 124.25
1.97 0.02 173.65 177.94 182.12 186.22 190.22 194.14
2.36 0.03 250.05 256.23 262.26 268.15 273.92 279.57
2.76 0.04 340.35 348.75 356.96 364.98 372.83 380.52
3.15 0.05 444.54 455.51 466.23 476.71 486.97 497.01
3.54 0.07 562.62 576.51 590.08 603.34 616.32 629.02
3.94 0.08 694.59 711.74 728.49 744.86 760.88 776.57
4.33 0.10 840.45 861.21 881.47 901.28 920.67 939.65
4.72 0.12 1000.21 1024.94 1049.03 1072.60 1095.67 1118.27
5.12 0.14 1173.85 1202.84 1231.15 1258.82 1285.89 1312.41
5.51 0.17 1361.39 1395.01 1427.84 1459.93 1491.33 1522.08
5.91 0.19 1562.82 1601.42 1639.10 1675.94 1711.99 1747.29
6.30 0.22 1778.15 1822.06 1864.93 1906.85 1947.86 1988.03
6.69 0.24 2007.36 2056.93 2105.34 2152.65 2198.95 2244.30
7.09 0.27 2250.47 2306.04 2360.31 2413.36 2465.26 2516.10
7.48 0.31 2507.46 2569.38 2629.85 2688.95 2746.79 2803.43
7.87 0.34 2778.35 2846.96 2913.96 2979.45 3043.53 3106.29
8.27 0.37 3063.13 3138.78 3212.64 3284.84 3355.49 3424.69
8.66 0.41 3361.81 3444.83 3525.89 3605.14 3682.67 3758.61
9.06 0.45 3674.37 3765.11 3853.71 3940.32 4025.07 4108.07
9.45 0.49 4000.83 4099.63 4196.10 4290.41 4382.69 4473.06
9.84 0.53 4341.18 4448.38 4553.06 4655.39 4755.52 4853.58
10.24 0.57 4695.42 4811.37 4924.59 5035.27 5143.57 5249.63
10.63 0.62 5063.55 5188.59 5310.69 5430.05 5546.84 5661.22
11.02 0.66 5445.57 5580.05 5711.36 5839.72 5965.32 6088.33
11.42 0.71 5841.49 5985.74 6126.60 6264.30 6399.03 6530.98
11.81 0.76 6251.29 6405.67 6556.41 6703.76 6847.95 6989.16
12.20 0.81 6674.99 6839.83 7000.79 7158.13 7312.09 7462.87
12.60 0.87 7112.58 7288.23 7459.74 7627.39 7791.44 7952.11
12.99 0.92 7564.06 7750.86 7933.26 8111.56 8286.02 8456.88
13.39 0.98 8029.44 8227.73 8421.35 8610.61 8795.81 8977.18
13.78 1.04 8508.70 8718.83 8924.00 9124.57 9320.82 9513.02
14.17 1.10 9001.86 9224.16 9441.23 9653.42 9861.05 10064.39
14.57 1.16 9508.91 9743.73 9973.03 10197.17 10416.49 10631.29
14.96 1.22 10029.85 10277.54 10519.40 10755.82 10987.15 11213.72
15.35 1.29 10564.68 10825.58 11080.33 11329.36 11573.03 11811.68
15.75 1.35 11113.41 11387.86 11655.84 11917.80 12174.13 12425.17

Using equation Q = (C)(A)(2gh)0.5, with the following variables: Q = Orifice discharge, C = Orifice constant = 0.61 (varies by type of orifice, value considered conservative), A = Orifce Area m2, g = 9.8 m/s2, h = Head of Orifice m

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For more information:
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E-mail: ag.info.omafra@ontario.ca
Author: Robert P. Stone, P. Eng., Engineer, Soil/OMAFRA
Creation Date: 04 July 2005
Last Reviewed: 29 March 2007