This section specifies the types of green infrastructure BMPs
that may be used to satisfy the groundwater recharge, stormwater runoff
quality, and stormwater runoff quantity standards.
A. To satisfy the groundwater recharge and stormwater runoff quality standards at §§
211-9 and
211-10, the design engineer shall utilize green infrastructure BMPs identified in Table 1 at §
211-7F and/or an alternative stormwater management measure approved in accordance with §
211-7G. The following green infrastructure BMPs are subject to the following maximum contributory drainage area limitations:
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 3 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
|
B. To satisfy the stormwater runoff quantity standards at §
211-11, the design engineer shall utilize BMPs from Table 1 or from Table 2 and/or an alternative stormwater management measure approved in accordance with §
211-7G.
C. If a variance in accordance with N.J.A.C. 7:8-4.6 or a waiver from strict compliance in accordance with §
211-7D is granted from the requirements of this section, then BMPs from Table 1, 2, or 3, and/or an alternative stormwater management measure approved in accordance with §
211-7G may be used to meet the groundwater recharge, stormwater runoff quality, and stormwater runoff quantity standards at §§
211-9,
211-10 and
211-11.
D. For separate or combined storm sewer improvement projects, such as sewer separation, undertaken by a government agency or public utility (for example, a sewerage company), the requirements of this section shall only apply to areas owned in fee simple by the government agency or utility, and areas within a right-of-way or easement held or controlled by the government agency or utility; the entity shall not be required to obtain additional property or property rights to fully satisfy the requirements of this section. Regardless of the amount of area of a separate or combined storm sewer improvement project subject to the green infrastructure requirements of this section, each project shall fully comply with the applicable groundwater recharge, stormwater runoff quality control, and stormwater runoff quantity standards at §§
211-9,
211-10 and
211-11, unless the project is granted a waiver from strict compliance in accordance with §
211-7D.
This section contains minimum design and performance standards
to encourage and control infiltration and groundwater recharge. The
minimum design and performance standards for groundwater recharge
are as follows:
A. The design engineer shall, using the assumptions and factors for stormwater runoff and groundwater recharge calculations within §
211-12, demonstrate compliance with either Subsection
A(1) or
(2) below. Additional standards set forth in Subsection
A(3) and
(4) may apply as required.
(1) Demonstrate through hydrologic and hydraulic analysis that the site
and its stormwater management measures maintain 100% of the average
annual preconstruction groundwater recharge volume for the site; or
(2) Demonstrate through hydrologic and hydraulic analysis that the increase
of stormwater runoff volume from preconstruction to postconstruction
for the two-year storm is infiltrated.
(3) Nonexempt projects located in a current deficit area. Where the project
is located in a current deficit area as identified in Exhibit A, the project shall demonstrate through hydrologic and hydraulic analysis that the site and its stormwater management measures provide for enhanced recharge standards set forth in Subsection
A(5) below.
(4) Nonexempt projects located in a Municipally Important Groundwater
Recharge Area. Where the project is located in a Municipally Important
Groundwater Recharge Area as identified in Exhibit B, the following standards shall apply:
(a)
Where disturbance is permitted in accordance with this section,
it shall be limited to no greater than 15% of the Municipally Important
Groundwater Recharge Area on the site and shall preferentially be
sited on that portion of Municipally Important Groundwater Recharge
Area that has the lowest groundwater recharge rates.
(b)
Where disturbance to the Municipally Important Groundwater Recharge Area is permitted, the project shall demonstrate through hydrologic and hydraulic analysis that the site and its stormwater management measures provide for enhanced recharge standards set forth in Subsection
A(5) below.
(5) The enhanced recharge standards. Nonexempt projects that are subject to the enhanced recharge requirements by Subsection
A(3) or
(4) above, shall apply the following standards, either:
(a)
Recharge 125% of the percentage of the average annual preconstruction
groundwater recharge volume for the site; or
(b)
In addition to complying with the infiltration requirements of §
211-11A(2) retain on-site with no discharge, the stormwater quality design volume (SWQDv), defined as the runoff from the 1.25-inch, two-hour rainfall event. Where meeting the infiltration requirement will not result in retention of the full SWQDv, the major development shall retain any additional volume to meet the requirements of this section through additional infiltration, or through evapotranspiration or capture and on-site reuse of rainfall.
B. The following types of stormwater shall not be recharged:
(1) Stormwater from areas of high pollutant loading. High pollutant loading
areas are areas in industrial and commercial developments where solvents
and/or petroleum products are loaded/unloaded, stored, or applied,
areas where pesticides are loaded/unloaded or stored; areas where
hazardous materials are expected to be present in greater than "reportable
quantities" as defined by the United States Environmental Protection
Agency (EPA) at 40 CFR 302.4; areas where recharge would be inconsistent
with a Department-approved remedial action work plan or landfill closure
plan and areas with high risks for spills of toxic materials, such
as gas stations and vehicle maintenance facilities; and
(2) Industrial stormwater exposed to source material. "Source material"
means any material(s) or machinery, located at an industrial facility,
that is directly or indirectly related to process, manufacturing or
other industrial activities, which could be a source of pollutants
in any industrial stormwater discharge to groundwater. Source materials
include, but are not limited to, raw materials; intermediate products;
final products; waste materials; by-products; industrial machinery
and fuels, and lubricants, solvents, and detergents that are related
to process, manufacturing, or other industrial activities that are
exposed to stormwater.
(3) Carbonate rock areas, where surficial or subsurface karst features
have been identified and recharge facilities cannot be designed in
a manner that would eliminate the concentrated subsurface release
of stormwater. (Note: the more presence of carbonate bedrock does
not constitute a karst feature.)
C. The design engineer shall assess the hydraulic impact on the groundwater
table and design the site so as to avoid adverse hydraulic impacts.
Potential adverse hydraulic impacts include, but are not limited to,
exacerbating a naturally or seasonally high-water table so as to cause
surficial ponding, flooding of basements, or interference with the
proper operation of subsurface sewage disposal systems and other subsurface
structures in the vicinity or downgradient of the groundwater recharge
area.
D. The mitigation required for nonexempt projects. In lieu of on-site
recharge, the applicant shall be responsible for providing mitigation
of the groundwater recharge volume in the required amount. The applicant
should provide mitigation within the following areas, in order of
priority:
(1) The same development site where feasible;
(2) The same HUC14 subwatershed; or
(3) An interrelated HUC14 subwatershed where no feasible option exists
in the same HUC14 subwatershed.
E. If none of the above options are feasible or achievable, then the applicant shall comply with the mitigation requirements set forth in §
211-26.
This section contains the minimum design and performance standards
to control stormwater runoff quality impacts of major development.
Stormwater runoff quality standards are applicable when the major
development results in an increase of 1/4 acre or more of regulated
motor vehicle surface.
A. Stormwater management measures shall be designed to reduce the post-
construction load of total suspended solids (TSS) in stormwater runoff
generated from the water quality design storm as follows:
(1) Eighty percent TSS removal of the anticipated load, expressed as
an annual average, shall be achieved for the stormwater runoff from
the net increase of motor vehicle surface.
(2) If the surface is considered regulated motor vehicle surface because
the water quality treatment for an area of motor vehicle surface that
is currently receiving water quality treatment either by vegetation
or soil, by an existing stormwater management measure, or by treatment
at a wastewater treatment plant is to be modified or removed, the
project shall maintain or increase the existing TSS removal of the
anticipated load expressed as an annual average.
B. The requirement to reduce TSS does not apply to any stormwater runoff in a discharge regulated under a numeric effluent limitation for TSS imposed under the New Jersey Pollutant Discharge Elimination System (NJPDES) rules, N.J.A.C. 7:14A, or in a discharge specifically exempt under a NJPDES permit from this requirement. Every major development, including any that discharge into a combined sewer system, shall comply with Subsection
A above, unless the major development is itself subject to a NJPDES permit with a numeric effluent limitation for TSS or the NJPDES permit to which the major development is subject exempts the development from a numeric effluent limitation for TSS.
C. The water quality design storm is 1.25 inches of rainfall in two
hours. Water quality calculations shall take into account the distribution
of rain from the water quality design storm, as reflected in Table
4, below. The calculation of the volume of runoff may take into account
the implementation of stormwater management measures.
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
|
0.00830
|
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
|
D. If more than one BMP in series is necessary to achieve the required
80% TSS reduction for a site, the applicant shall utilize the following
formula to calculate TSS reduction:
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.
|
E. Stormwater management measures shall also be designed to reduce, to the maximum extent feasible, the post-construction nutrient load of the anticipated load from the developed site in stormwater runoff generated from the water quality design storm. In achieving reduction of nutrients to the maximum extent feasible, the design of the site shall include green infrastructure BMPs that optimize nutrient removal while still achieving the performance standards in §§
211-9,
211-10 and
211-11.
F. In accordance with the definition of "FW1" at N.J.A.C. 7:9B-1.4,
stormwater management measures shall be designed to prevent any increase
in stormwater runoff to waters classified as FW1.
G. The Flood Hazard Area Control Act Rules at N.J.A.C. 7:13-4.1(c)1
establish 300-foot riparian zones along Category One waters, as designated
in the Surface Water Quality Standards at N.J.A.C. 7:9B, and certain
upstream tributaries to Category One waters. A person shall not undertake
a major development that is located within or discharges into a 300-foot
riparian zone without prior authorization from the Department under
N.J.A.C. 7:13.
H. Pursuant to the Flood Hazard Area Control Act Rules at N.J.A.C. 7:13-11.2(j)3i,
runoff from the water quality design storm that is discharged within
a 300-foot riparian zone shall be treated in accordance with this
section to reduce the post-construction load of total suspended solids
by 95% of the anticipated load from the developed site, expressed
as an annual average.
I. This stormwater runoff quality standards do not apply to the construction
of one individual single-family dwelling, provided that it is not
part of a larger development or subdivision that has received preliminary
or final site plan approval prior to December 3, 2018, and that the
motor vehicle surfaces are made of permeable material(s), such as
gravel, dirt, and/or shells.
This section contains the minimum design and performance standards
to control stormwater runoff quantity impacts of major development.
A. In order to control stormwater runoff quantity impacts, the design engineer shall, using the assumptions and factors for stormwater runoff calculations at §
211-12, complete one of the following:
(1) Demonstrate through hydrologic and hydraulic analysis that for stormwater
leaving the site, post-construction runoff hydrographs for the two-,
ten-, and 100-year storm events do not exceed, at any point in time,
the preconstruction runoff hydrographs for the same storm events;
(2) Demonstrate through hydrologic and hydraulic analysis that there
is no increase, as compared to the preconstruction condition, in the
peak runoff rates of stormwater leaving the site for the two-, ten-
and 100-year storm events and that the increased volume or change
in timing of stormwater runoff will not increase flood damage at or
downstream of the site. This analysis shall include the analysis of
impacts of existing land uses and projected land uses assuming full
development under existing zoning and land use ordinances in the drainage
area; or
(3) Design stormwater management measures so that the post-construction
peak runoff rates for the two-, ten- and 100-year storm events are
50%, 75% and 80%, respectively, of the preconstruction peak runoff
rates. The percentages apply only to the post-construction stormwater
runoff that is attributable to the portion of the site on which the
proposed development or project is to be constructed.
B. The stormwater runoff quantity standards shall be applied at the
site's boundary to each abutting lot, roadway, watercourse, or
receiving storm sewer system.