Best Management Practice
|
Maximum Contributory Drainage Area
(acres)
|
---|---|
Dry well
|
1
|
Manufactured treatment device
|
2.5
|
Pervious pavement systems
|
Area of additional inflow cannot exceed three times the area
occupied by the BMP
|
Small-scale bioretention systems
|
2.5
|
Small-scale infiltration basin
|
2.5
|
Small-scale sand filter
|
2.5
|
Table 1
| |||||
---|---|---|---|---|---|
Water Quality Design Storm Distribution
| |||||
Time
(minutes)
|
Cumulative Rainfall
(inches)
|
Time
(minutes)
|
Cumulative Rainfall
(inches)
|
Time
(minutes)
|
Cumulative Rainfall
(inches)
|
1
|
0.00166
|
41
|
0.1728
|
81
|
1.0906
|
2
|
0.00332
|
42
|
0.1796
|
82
|
1.0972
|
3
|
0.00498
|
43
|
0.1864
|
83
|
1.1038
|
4
|
0.00664
|
44
|
0.1932
|
84
|
1.1104
|
5
|
0.00830
|
45
|
0.2000
|
85
|
1.1170
|
6
|
0.00996
|
46
|
0.2117
|
86
|
1.1236
|
7
|
0.01162
|
47
|
0.2233
|
87
|
1.1302
|
8
|
0.01328
|
48
|
0.2350
|
88
|
1.1368
|
9
|
0.01494
|
49
|
0.2466
|
89
|
1.1434
|
10
|
0.01660
|
50
|
0.2583
|
90
|
1.1500
|
11
|
0.01828
|
51
|
0.2783
|
91
|
1.1550
|
12
|
0.01996
|
52
|
0.2983
|
92
|
1.1600
|
13
|
0.02164
|
53
|
0.3183
|
93
|
1.1650
|
14
|
0.02332
|
54
|
0.3383
|
94
|
1.1700
|
15
|
0.02500
|
55
|
0.3583
|
95
|
1.1750
|
16
|
0.03000
|
56
|
0.4116
|
96
|
1.1800
|
17
|
0.03500
|
57
|
0.4650
|
97
|
1.1850
|
18
|
0.04000
|
58
|
0.5183
|
98
|
1.1900
|
19
|
0.04500
|
59
|
0.5717
|
99
|
1.1950
|
20
|
0.05000
|
60
|
0.6250
|
100
|
1.2000
|
21
|
0.05500
|
61
|
0.6783
|
101
|
1.2050
|
22
|
0.06000
|
62
|
0.7317
|
102
|
1.2100
|
23
|
0.06500
|
63
|
0.7850
|
103
|
1.2150
|
24
|
0.07000
|
64
|
0.8384
|
104
|
1.2200
|
25
|
0.07500
|
65
|
0.8917
|
105
|
1.2250
|
26
|
0.08000
|
66
|
0.9117
|
106
|
1.2267
|
27
|
0.08500
|
67
|
0.9317
|
107
|
1.2284
|
28
|
0.09000
|
68
|
0.9517
|
108
|
1.2300
|
29
|
0.09500
|
69
|
0.9717
|
109
|
1.2317
|
30
|
0.10000
|
70
|
0.9917
|
110
|
1.2334
|
31
|
0.10660
|
71
|
1.0034
|
111
|
1.2351
|
32
|
0.11320
|
72
|
1.0150
|
112
|
1.2367
|
33
|
0.11980
|
73
|
1.0267
|
113
|
1.2384
|
34
|
0.12640
|
74
|
1.0383
|
114
|
1.2400
|
35
|
0.13300
|
75
|
1.0500
|
115
|
1.2417
|
36
|
0.13960
|
76
|
1.0568
|
116
|
1.2434
|
37
|
0.14620
|
77
|
1.0636
|
117
|
1.2450
|
38
|
0.15280
|
78
|
1.0704
|
118
|
1.2467
|
39
|
0.15940
|
79
|
1.0772
|
119
|
1.2483
|
40
|
0.16600
|
80
|
1.0840
|
120
|
1.2500
|
R = A + B - (A x B)/100
|
Where:
| ||
R
|
=
|
total TSS percent load removal from application of both BMPs.
|
A
|
=
|
the TSS percent removal rate applicable to the first BMP.
|
B
|
=
|
the TSS percent removal rate applicable to the second BMP.
|