Table 1: Green Infrastructure BMPs for Groundwater Recharge,
Stormwater Runoff Quality, and/or Stormwater Runoff Quantity
| ||||
---|---|---|---|---|
Best Practice Management
|
Stormwater Runoff Quality TSS Removal Rate
(percent)
|
Stormwater Runoff Quantity
|
Groundwater Recharge
|
Minimum Separation from Seasonal High Water Table
(feet)
|
Cistern
|
0
|
Yes
|
No
|
—
|
Dry well(a)
|
0
|
No
|
Yes
|
2
|
Grass swale
|
50 or less
|
No
|
No
|
2(e)
|
1(f)
| ||||
Green roof
|
0
|
Yes
|
No
|
—
|
Manufactured treatment device(a), (g)
|
50 or 80
|
No
|
No
|
Dependent upon the device
|
Pervious paving system(a)
|
80
|
Yes
|
Yes(b)
|
2(b)
|
No(c)
|
2(c)
| |||
Small-scale bioretention basin(a)
|
80 or 90
|
Yes
|
Yes(b)
|
2(b)
|
No(c)
|
1(c)
| |||
Small-scale infiltration basin(a)
|
80
|
Yes
|
Yes
|
2
|
Small scale sand filter(a)
|
80
|
Yes
|
Yes
|
2
|
Vegetative filter strip
|
60-80
|
No
|
No
|
—
|
Table 2: Green Infrastructure BMPs for Stormwater Runoff Quantity
(or for Groundwater Recharge and/or Stormwater Runoff Quality with
a Variance from N.J.A.C. 7:8-5.3)
| ||||
---|---|---|---|---|
Best Management Practice
|
Stormwater Runoff Quality TSS Removal Rate
n(percent)
|
Stormwater Runoff Quantity
|
Groundwater Recharge
|
Minimum Separation from Seasonal High Water Table
(feet)
|
Bioretention system
|
80 or 90
|
Yes
|
Yes(b)
|
2(b)
|
No(c)
|
1(c)
| |||
Infiltration basin
|
80
|
Yes
|
Yes
|
2
|
Sand filter(b)
|
80
|
Yes
|
Yes
|
2
|
Standard constructed wetland
|
90
|
Yes
|
No
|
2(i)
|
Wet pond(d)
|
50-90
|
Yes
|
No
|
2(i)
|
Table 3: BMPs for Groundwater Recharge, Stormwater Runoff Quality,
and/or Stormwater Runoff Quantity only with a Variance from N.J.A.C.
7:8-5.3
| ||||
---|---|---|---|---|
Best Management Practice
|
Stormwater Runoff Quality TSS Removal Rate
(percent)
|
Stormwater Runoff Quantity
|
Groundwater Recharge
|
Minimum Separation from Seasonal High Water Table
(feet)
|
Blue roof
|
0
|
Yes
|
No
|
N/A
|
Extended detention basin
|
40-60
|
Yes
|
No
|
2
|
Manufactured treatment device(h)
|
50 or 80
|
No
|
No
|
Dependent upon the device
|
Sand filter(c)
|
80
|
Yes
|
No
|
2
|
Subsurface gravel wetland
|
90
|
No
|
No
|
2
|
Wet pond
|
50-90
|
Yes
|
No
|
2(i)
|
Footnotes to Tables 1, 2, and 3:
| |
---|---|
(a)
|
Subject to the applicable contributory drainage area limitation specified at § 203-263N(2).
|
(b)
|
Designed to infiltrate into the subsoil.
|
(c)
|
Designed with underdrains, where stormwater percolates into
the underdrain through the soils and is not directed to the underdrain
by an outlet control structure.
|
(d)
|
Designed to maintain at least a ten-foot wide area of native
vegetation along at least 50% of the shoreline and to include a stormwater
runoff retention component designed to capture stormwater runoff for
beneficial reuse, such as irrigation.
|
(e)
|
Designed with a slope of less than 2%.
|
(f)
|
Designed with a slope of equal to or greater than 2%.
|
(g)
|
Manufactured treatment devices that meet the definition of green infrastructure at § 203-262.
|
(h)
|
Manufactured treatment devices that do not meet the definition of green infrastructure at § 203-262.
|
(i)
|
The top elevation of the impermeable layer or liner must maintain
this two-foot minimum separation to the seasonal high water table.
|
Best Management Practice
|
Maximum Contributory Drainage Area
|
---|---|
Dry well
|
1 acre
|
Manufactured treatment device
|
2.5 acres
|
Pervious pavement system
|
Area of additional inflow cannot exceed 3 times the area occupied
by the BMP
|
Small-scale bioretention systems
|
2.5 acres
|
Small-scale infiltration basin
|
2.5 acres
|
Small-scale sand filter
|
2.5 acres
|
Table 4: 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
|
0.0083
|
45
|
0.2
|
85
|
1.117
|
6
|
0.00996
|
46
|
0.2117
|
86
|
1.1236
|
7
|
0.01162
|
47
|
0.2233
|
87
|
1.1302
|
8
|
0.01328
|
48
|
0.235
|
88
|
1.1368
|
9
|
0.01494
|
49
|
0.2466
|
89
|
1.1434
|
10
|
0.0166
|
50
|
0.2583
|
90
|
1.15
|
11
|
0.01828
|
51
|
0.2783
|
91
|
1.155
|
12
|
0.01996
|
52
|
0.2983
|
92
|
1.16
|
13
|
0.02164
|
53
|
0.3183
|
93
|
1.165
|
14
|
0.02332
|
54
|
0.3383
|
94
|
1.17
|
15
|
0.025
|
55
|
0.3583
|
95
|
1.175
|
16
|
0.03
|
56
|
0.4116
|
96
|
1.18
|
17
|
0.035
|
57
|
0.465
|
97
|
1.185
|
18
|
0.04
|
58
|
0.5183
|
98
|
1.19
|
19
|
0.045
|
59
|
0.5717
|
99
|
1.195
|
20
|
0.05
|
60
|
0.625
|
100
|
1.2
|
21
|
0.055
|
61
|
0.6783
|
101
|
1.205
|
22
|
0.06
|
62
|
0.7317
|
102
|
1.21
|
23
|
0.065
|
63
|
0.785
|
103
|
1.215
|
24
|
0.07
|
64
|
0.8384
|
104
|
1.22
|
25
|
0.075
|
65
|
0.8917
|
105
|
1.225
|
26
|
0.08
|
66
|
0.9117
|
106
|
1.2267
|
27
|
0.085
|
67
|
0.9317
|
107
|
1.2284
|
28
|
0.09
|
68
|
0.9517
|
108
|
1.23
|
29
|
0.095
|
69
|
0.9717
|
109
|
1.2317
|
30
|
0.1
|
70
|
0.9917
|
110
|
1.2334
|
31
|
0.1066
|
71
|
1.0034
|
111
|
1.2351
|
32
|
0.1132
|
72
|
1.015
|
112
|
1.2367
|
33
|
0.1198
|
73
|
1.0267
|
113
|
1.2384
|
34
|
0.1264
|
74
|
1.0383
|
114
|
1.24
|
35
|
0.133
|
75
|
1.05
|
115
|
1.2417
|
36
|
0.1396
|
76
|
1.0568
|
116
|
1.2434
|
37
|
0.1462
|
77
|
1.0636
|
117
|
1.245
|
38
|
0.1528
|
78
|
1.0704
|
118
|
1.2467
|
39
|
0.1594
|
79
|
1.0772
|
119
|
1.2483
|
40
|
0.166
|
80
|
1.084
|
120
|
1.25
|
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.
|
Plant Type
|
Number of Plants (per 1,000 linear feet)
|
---|---|
Shade trees
|
80
|
Evergreen trees
|
40
|
Ornamental trees
|
10
|
Plant Type
|
Size
|
---|---|
Shade trees
|
2 inches caliper
|
Plant Type
|
Size
|
---|---|
Ornamental trees
|
feet high
|
Evergreen trees
|
6 feet high
|
Evergreen and deciduous shrubs high
|
2.5 to 3 feet
|
Plant Type
|
Number of Plants (per 1,000 linear feet)
|
---|---|
Shade trees
|
80
|
Evergreen trees
|
40
|
Ornamental trees
|
10
|
Shrubs
|
50
|
Qp = CIA
| ||
Where:
| ||
Qp
|
=
|
The peak runoff rate in cubic feet per second
|
C
|
=
|
The runoff coefficient
|
I
|
=
|
The average rainfall intensity in inches per hour occurring
at the time of concentration tc
|
tc
|
=
|
The time of concentration in minutes
|
A
|
=
|
The size of the drainage area in acres
|
Table 1
| |||||
---|---|---|---|---|---|
Typical Runoff Coefficients (C Values) For 100-Year Frequency
| |||||
Storm Land Use Description
|
Hydrologic Soil Group
| ||||
A
|
B
|
C
|
D
| ||
Cultivated land:
| |||||
Without conservation treatment
|
0.49
|
0.67
|
0.81
|
0.88
| |
With conservation treatment
|
0.27
|
0.43
|
0.61
|
0.67
| |
Pasture or range land:
| |||||
Poor condition
|
0.38
|
0.63
|
0.78
|
0.84
| |
Good condition
|
NA
|
0.25
|
0.51
|
0.65
| |
Meadow: good condition
|
NA
|
NA
|
0.44
|
0.61
| |
Wood or forest land:
| |||||
Thin stand, poor cover, no mulch
|
NA
|
NA
|
0.59
|
0.79
| |
Good cover
|
NA
|
NA
|
0.45
|
0.59
| |
Open spaces, lawns, parks, golf courses, cemeteries:
| |||||
Good condition, grass cover on NA 75% or more of
area
|
0.25
|
0.51
|
0.65
| ||
Fair condition, grass cover on NA 50% to 75% of
area
|
0.45
|
0.63
|
0.74
| ||
Commercial and business areas (85% 0.84 impervious)
|
0.90
|
0.93
|
0.96
| ||
Industrial districts (72% impervious)
|
0.67
|
0.81
|
0.88
|
0.92
| |
Residential:
| |||||
Average Lot Size
|
Average Imperviousness
| ||||
1/8 acre
|
65%
|
0.59
|
0.76
|
0.86
|
0.90
|
1/4 acre
|
38%
|
0.25
|
0.55
|
0.70
|
0.80
|
1/3 acre
|
30%
|
NA
|
0.49
|
0.67
|
0.78
|
1/2 acre
|
25%
|
NA
|
0.45
|
0.65
|
0.76
|
1 acre
|
20%
|
NA
|
0.41
|
0.63
|
0.74
|
Paved parking lots, roofs, driveways, etc.
|
0.99
|
0.99
|
0.99
|
0.99
| |
Streets and roads:
| |||||
Paved with curbs and storm sewers
|
0.99
|
0.99
|
0.99
|
0.99
| |
Gravel
|
0.57
|
0.76
|
0.84
|
0.88
| |
Dirt
|
0.49
|
0.69
|
0.80
|
0.84
|
NOTE: NA denotes information is not available; design engineers
should rely on another authoritative source.
|
SOURCE: Technical Manual for Land Use Regulation Program, Department
of Environmental Protection, Bureaus of Inland and Coastal Regulations,
Stream Encroachment Permits (Trenton, New Jersey, revised September
1995), p.12.
|
Q = (1.486/n) AR2/3 S1/2
| ||
Where:
| ||
n
|
=
|
Manning's roughness coefficient
|
A
|
=
|
Cross-sectional area of flow in square feet
|
R
|
=
|
Hydraulic radius in feet R = A/P where P is equal to the wetted
perimeter measured in feet and defined as the length of a line of
contact between the flowing water and the channel
|
S
|
=
|
Slope of energy grade line in feet per foot
|
The Mannings's roughness coefficients used by design engineers
appear in Table 2.
|
Table 3
| ||
---|---|---|
Minimum Depth Of Coverage Over Concrete Pipe
| ||
Pipe Diameter
(in inches)
|
ASTM Class Pipe
|
Minimum Cover
(surface to top of pipe in inches)
|
12
|
III
|
17
|
IV
|
12
| |
V
|
7
| |
15
|
III
|
16
|
IV
|
11
| |
V
|
7
| |
18
|
III
|
16
|
IV
|
10
| |
V
|
6
| |
24
|
III
|
15
|
IV
|
6
| |
V
|
6
| |
30
|
III
|
10
|
IV
|
6
| |
V
|
6
| |
36 and above
|
III
|
6
|
The Division of Water Quality, New Jersey Department of Environmental
Protection, Mail Code 401-02B, PO Box 420, Trenton, New Jersey 08625-0420.
|