A. 
Stormwater management measures for major development shall be designed to provide erosion control, groundwater recharge, stormwater runoff quantity control, and stormwater runoff quality treatment as follows:
(1) 
The minimum standards for erosion control are those established under the Soil and Sediment Control Act, N.J.S.A. 4:24-39 et seq., and implementing rules at N.J.A.C. 2:90.
(2) 
The minimum standards for groundwater recharge, stormwater quality, and stormwater runoff quantity shall be met by incorporating green infrastructure.
B. 
The standards in this chapter apply only to new major development and are intended to minimize the impact of stormwater runoff on water quality and water quantity in receiving water bodies and maintain groundwater recharge.
A. 
The development shall incorporate a maintenance plan for the stormwater management measures incorporated into the design of a major development in accordance with § 138-18.
B. 
Stormwater management measures shall avoid adverse impacts of concentrated flow on habitat for threatened and endangered species as documented in the Department's Landscape Project or Natural Heritage Database established under N.J.S.A. 13:1 B-15.147 through 15.150, particularly Helonias bullata (swamp pink) and/or Clemmys muhlnebergi (bog turtle).
C. 
The following linear development projects are exempt from the groundwater recharge, stormwater runoff quality, and stormwater runoff quantity requirements of §§ 138-10, 138-11, and 138-12:
(1) 
The construction of an underground utility line provided that the disturbed areas are revegetated upon completion;
(2) 
The construction of an aboveground utility line provided that the existing conditions are maintained to the maximum extent practicable; and
(3) 
The construction of a public pedestrian access, such as a sidewalk or trail with a maximum width of 14 feet, provided that the access is made of permeable material.
D. 
A waiver from strict compliance from the green infrastructure, groundwater recharge, stormwater runoff quality, and stormwater runoff quantity requirements of §§ 138-9, 138-10, 138-11, and 138-12 may be obtained for the enlargement of an existing public roadway or railroad; or the construction or enlargement of a public pedestrian access, provided that the following conditions are met:
(1) 
The applicant demonstrates that there is a public need for the project that cannot be accomplished by any other means;
(2) 
The applicant demonstrates through an alternatives analysis, that through the use of stormwater management measures, the option selected complies with the requirements of §§ 138-9, 138-10, 138-11, and 138-12 to the maximum extent practicable;
(3) 
The applicant demonstrates that, in order to meet the requirements of §§ 138-9, 138-10, 138-11, and 138-12, existing structures currently in use, such as homes and buildings, would need to be condemned; and
(4) 
The applicant demonstrates that it does not own or have other rights to areas, including the potential to obtain through condemnation lands not falling under D(3) above within the upstream drainage area of the receiving stream, that would provide additional opportunities to mitigate the requirements of §§ 138-9, 138-10, 138-11, and 138-12 that were not achievable on site.
E. 
Tables 1 through 3 below summarize the ability of stormwater best management practices identified and described in the New Jersey Stormwater Best Management Practices Manual to satisfy the green infrastructure, groundwater recharge, stormwater runoff quality and stormwater runoff quantity standards specified in §§ 138-9, 138-10, 138-11, and 138-12. When designed in accordance with the most current version of the New Jersey Stormwater Best Management Practices Manual, the stormwater management measures found at N.J.A.C. 7:8-5.2(f) Tables 5-1, 5-2 and 5-3 and listed below in Tables 1, 2 and 3 are presumed to be capable of providing stormwater controls for the design and performance standards as outlined in the tables below. Upon amendments of the New Jersey Stormwater Best Management Practices to reflect additions or deletions of BMPs meeting these standards, or changes in the presumed performance of BMPs designed in accordance with the New Jersey Stormwater BMP Manual, the Department shall publish in the New Jersey Registers a notice of administrative change revising the applicable table. The most current version of the BMP Manual can be found on the Department's website at: https://njstormwater.org/bmp_manual2.htm.
F. 
Where the BMP tables in the NJ Stormwater Management Rule are different due to updates or amendments with the tables in this chapter the BMP Tables in the Stormwater Management rule at N.J.A.C. 7:8-5.2(f) shall take precedence.
Table 1
Green Infrastructure BMPs for Groundwater Recharge, Stormwater Runoff Quality, and/or Stormwater Runoff Quantity
Best Management Practice
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)
No(c)
2(b)
1(c)
Small-scale bioretention basin(a)
80 or 90
Yes
Yes(b)
No(c)
2(b)
1(c)
Small-scale infiltration basin(a)
80
Yes
Yes
2
Small-scale sand filter
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 Waiver or 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)
Bioretention system
80 or 90
Yes
Yes(b)
No(c)
2(b)
1(c)
Infiltration basin
80
Yes
Yes
2
Sand filter(b)
80
Yes
Yes
2
Standard constructed wetland
90
Yes
No
N/A
Wet pond(d)
50-90
Yes
No
N/A
Table 3
BMPs for Groundwater Recharge, Stormwater Runoff Quality, and/or Stormwater Runoff Quantity
only with a Waiver or 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
1
Manufactured treatment device(h)
50 or 80
No
No
Dependent upon the device
Sand filter(c)
80
Yes
No
1
Subsurface gravel wetland
90
No
No
1
Wet pond
50-90
Yes
No
N/A
Notes to Tables 1, 2, and 3:
(a)
Subject to the applicable contributory drainage area limitation specified at § 138-9A;
(b)
Designed to infiltrate into the subsoil;
(c)
Designed with underdrains;
(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 green infrastructure definition at § 138-6;
(h)
Manufactured treatment devices that don't meet the green infrastructure definition at § 138-6.
G. 
An alternative stormwater management measure, alternative removal rate, and/or alternative method to calculate the removal rate may be used if the design engineer demonstrates the capability of the proposed alternative stormwater management measure and/or the validity of the alternative rate or method to the municipality. A copy of any approved alternative stormwater management measure, alternative removal rate, and/or alternative method to calculate the removal rate shall be provided to the Department in accordance with § 138-15B. Alternative stormwater management measures may be used to satisfy the requirements at § 138-9 only if the measures meet the definition of green infrastructure at § 138-6. Alternative stormwater management measures that function in a similar manner to a BMP listed at § 138-9A are subject to the contributory drainage area limitation specified at § 138-9A for that similarly functioning BMP. Alternative stormwater management measures approved in accordance with this section that do not function in a similar manner to any BMP listed at § 138-9A shall have a contributory drainage area less than or equal to 2.5 acres, except for alternative stormwater management measures that function similarly to cisterns, grass swales, green roofs, standard constructed wetlands, vegetative filter strips, and wet ponds, which are not subject to a contributory drainage area limitation. Alternative measures that function similarly to standard constructed wetlands or wet ponds shall not be used for compliance with the stormwater runoff quality standard unless a variance in accordance with N.J.A.C. 7:8-4.6 or a waiver from strict compliance in accordance with § 138-8D is granted from § 138-9.
H. 
Whenever the stormwater management design includes one or more BMPs that will infiltrate stormwater into subsoil, 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 or other subsurface structures within the zone of influence of the groundwater mound, or interference with the proper functioning of the stormwater management measure itself.
I. 
Design standards for stormwater management measures are as follows:
(1) 
Stormwater management measures shall be designed to take into account the existing site conditions, including, but not limited to, environmentally critical areas; wetlands; flood-prone areas; slopes; depth to seasonal high water table; soil type, permeability, and texture; drainage area and drainage patterns; and the presence of solution-prone carbonate rocks (limestone);
(2) 
Stormwater management measures shall be designed to minimize maintenance, facilitate maintenance and repairs, and ensure proper functioning. Trash racks shall be installed at the intake to the outlet structure, as appropriate, and shall have parallel bars with one-inch spacing between the bars to the elevation of the water quality design storm. For elevations higher than the water quality design storm, the parallel bars at the outlet structure shall be spaced no greater than one-third the width of the diameter of the orifice or one-third the width of the weir, with a minimum spacing between bars of one inch and a maximum spacing between bars of six inches. In addition, the design of trash racks must comply with the requirements of § 138-16B;
(3) 
Stormwater management measures shall be designed, constructed, and installed to be strong, durable, and corrosion-resistant. Measures that are consistent with the relevant portions of the Residential Site Improvement Standards at N.J.A.C. 5:21-7.3, 7.4, and 7.5 shall be deemed to meet this requirement;
(4) 
Stormwater management BMPs shall be designed to meet the minimum safety standards for stormwater management BMPs at § 138-16; and
(5) 
The size of the orifice at the intake to the outlet from the stormwater management BMP shall be a minimum of 2 1/2 inches in diameter.
J. 
Manufactured treatment devices may be used to meet the requirements of this subchapter, provided the pollutant removal rates are verified by the New Jersey Corporation for Advanced Technology and certified by the Department. Manufactured treatment devices that do not meet the definition of green infrastructure at § 138-6 may be used only under the circumstances described at § 138-9C.
K. 
Any application for a new agricultural development that meets the definition of major development at § 138-6 shall be submitted to the Soil Conservation District for review and approval in accordance with the requirements at §§ 138-9, 138-10, 138-11, and 138-12 and any applicable Soil Conservation District guidelines for stormwater runoff quantity and erosion control. For purposes of this section, "agricultural development" means land uses normally associated with the production of food, fiber, and livestock for sale. Such uses do not include the development of land for the processing or sale of food and the manufacture of agriculturally related products.
L. 
If there is more than one drainage area, the groundwater recharge, stormwater runoff quality, and stormwater runoff quantity standards at §§ 138-10, 138-11, and 138-12 shall be met in each drainage area, unless the runoff from the drainage areas converge on site and no adverse environmental impact would occur as a result of compliance with any one or more of the individual standards being determined utilizing a weighted average of the results achieved for that individual standard across the affected drainage areas.
M. 
Any stormwater management measure authorized under the municipal stormwater management plan or ordinance shall be reflected in a deed notice recorded in the Sussex County Clerk's Office. A form of deed notice shall be submitted to the municipality for approval prior to filing. The deed notice shall contain a description of the stormwater management measure(s) used to meet the green infrastructure, groundwater recharge, stormwater runoff quality, and stormwater runoff quantity standards at §§ 138-9, 138-10, 138-11, and 138-12 and shall identify the location of the stormwater management measure(s) in NAD 1983 State Plane New Jersey FIPS 2900 US Feet or Latitude and Longitude in decimal degrees. The deed notice shall also reference the maintenance plan required to be recorded upon the deed pursuant to § 138-18B(5). Prior to the commencement of construction, proof that the above-required deed notice has been filed shall be submitted to the municipality. Proof that the required information has been recorded on the deed shall be in the form of either a copy of the complete recorded document or a receipt from the clerk or other proof of recordation provided by the recording office. However, if the initial proof provided to the municipality is not a copy of the complete recorded document, a copy of the complete recorded document shall be provided to the municipality within 180 calendar days of the authorization granted by the municipality.
N. 
A stormwater management measure approved under the municipal stormwater management plan or ordinance may be altered or replaced with the approval of the municipality, if the municipality determines that the proposed alteration or replacement meets the design and performance standards pursuant to §§ 138-8 through 138-12 of this chapter and provides the same level of stormwater management as the previously approved stormwater management measure that is being altered or replaced. If an alteration or replacement is approved, a revised deed notice shall be submitted to the municipality for approval and subsequently recorded with the Sussex County Clerk's Office and shall contain a description and location of the stormwater management measure, as well as reference to the maintenance plan, in accordance with Subsection M above. Prior to the commencement of construction, proof that the above-required deed notice has been filed shall be submitted to the municipality in accordance with Subsection M above.
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 §§ 138-10 and 138-11, the design engineer shall utilize green infrastructure BMPs identified in Table 1 at § 138-8F and/or an alternative stormwater management measure approved in accordance with § 138-8G. The following green infrastructure BMPs are subject to the following maximum contributory drainage area limitations:
Best Management Practice
Maximum Contributory Drainage Area
Dry well
1 acre
Manufactured treatment device
2.5 acres
Pervious pavement systems
Area of additional inflow cannot exceed three 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
B. 
To satisfy the stormwater runoff quantity standards at § 138-12, the design engineer shall utilize BMPs from Table 1 or from Table 2 and/or an alternative stormwater management measure approved in accordance with § 138-8G.
C. 
If a variance in accordance with N.J.A.C. 7:8-4.6 or a waiver from strict compliance in accordance with § 138-8D 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 § 138-8G may be used to meet the groundwater recharge, stormwater runoff quality, and stormwater runoff quantity standards at §§ 138-10, 138-11 and 138-12.
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 §§ 138-10, 138-11 and 138-12, unless the project is granted a waiver from strict compliance in accordance with § 138-8D.
This section contains the minimum design and performance standards for groundwater recharge as follows:
A. 
The design engineer shall, using the assumptions and factors for stormwater runoff and groundwater recharge calculations at § 138-13, either:
(1) 
Demonstrate through hydrologic and hydraulic analysis that the site and its stormwater management measures maintain 100% of the average annual pre-construction groundwater recharge volume for the site; or
(2) 
Demonstrate through hydrologic and hydraulic analysis that the increase of stormwater runoff volume from pre-construction to post-construction for the two-year storm is infiltrated.
B. 
This groundwater recharge requirement does not apply to projects within the "urban redevelopment area," or to projects subject to Subsection C below.
C. 
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 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.
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:
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.
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 §§ 138-10, 138-11 and 138-12.
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)3.i, 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 § 138-13, 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 pre-construction runoff hydrographs for the same storm events;
(2) 
Demonstrate through hydrologic and hydraulic analysis that there is no increase, as compared to the pre-construction 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;
(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 pre-construction 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; or
(4) 
In tidal flood hazard areas, stormwater runoff quantity analysis in accordance with Subsection A(1), (2), and (3) above is required unless the design engineer demonstrates through hydrologic and hydraulic analysis that the increased volume, change in timing, or increased rate of the stormwater runoff, or any combination of the three will not result in additional flood damage below the point of discharge of the major development. No analysis is required if the stormwater is discharged directly into any ocean, bay, inlet, or the reach of any watercourse between its confluence with an ocean, bay, or inlet and downstream of the first water control structure.
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.
A. 
Stormwater runoff shall be calculated in accordance with the following:
(1) 
The design engineer shall calculate runoff using one of the following methods:
(a) 
The USDA Natural Resources Conservation Service (NRCS) methodology, including the NRCS Runoff, Equation and Dimensionless Unit Hydrograph, as described in Chapters 7, 9, 10, 15 and 16 Part 630, Hydrology National Engineering Handbook, incorporated herein by reference as amended and supplemented. This methodology is additionally described in Technical Release 55 - Urban Hydrology for Small Watersheds (TR-55), dated June 1986, incorporated herein by reference as amended and supplemented. Information regarding the methodology is available from the Natural Resources Conservation Service website at: https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1044171.pdf or at United States Department of Agriculture Natural Resources Conservation Service, 220 Davison Avenue, Somerset, New Jersey 08873; or
(b) 
The Rational Method for peak flow and the Modified Rational Method for hydrograph computations. The rational and modified rational methods are described in "Appendix A-9 Modified Rational Method" in the Standards for Soil Erosion and Sediment Control in New Jersey, January 2014. This document is available from the State Soil Conservation Committee or any of the Soil Conservation Districts listed at N.J.A.C. 2:90-1.3(a)3. The location, address, and telephone number for each Soil Conservation District is available from the State Soil Conservation Committee, PO Box 330, Trenton, New Jersey 08625. The document is also available at: http://www.nj.gov/agriculture/divisions/anr/pdf/2014NJSoilErosionControlStand ardsComplete.pdf.
(2) 
For the purpose of calculating runoff coefficients and groundwater recharge, there is a presumption that the pre-construction condition of a site or portion thereof is a wooded land use with good hydrologic condition. The term "runoff coefficient" applies to both the NRCS methodology above at § 138-13A(1)(a) and the Rational and Modified Rational Methods at § 138-13A(1)(b). A runoff coefficient or a groundwater recharge land cover for an existing condition may be used on all or a portion of the site if the design engineer verifies that the hydrologic condition has existed on the site or portion of the site for at least five years without interruption prior to the time of application. If more than one land cover have existed on the site during the five years immediately prior to the time of application, the land cover with the lowest runoff potential shall be used for the computations. In addition, there is the presumption that the site is in good hydrologic condition (if the land use type is pasture, lawn, or park), with good cover (if the land use type is woods), or with good hydrologic condition and conservation treatment (if the land use type is cultivation).
(3) 
In computing pre-construction stormwater runoff, the design engineer shall account for all significant land features and structures, such as ponds, wetlands, depressions, hedgerows, or culverts, that may reduce pre-construction stormwater runoff rates and volumes.
(4) 
In computing stormwater runoff from all design storms, the design engineer shall consider the relative stormwater runoff rates and/or volumes of pervious and impervious surfaces separately to accurately compute the rates and volume of stormwater runoff from the site. To calculate runoff from unconnected impervious cover, urban impervious area modifications as described in the NRCS Technical Release 55 - Urban Hydrology for Small Watersheds or other methods may be employed.
(5) 
If the invert of the outlet structure of a stormwater management measure is below the flood hazard design flood elevation as defined at N.J.A.C. 7:13, the design engineer shall take into account the effects of tailwater in the design of structural stormwater management measures.
B. 
Groundwater recharge may be calculated in accordance with the following: The New Jersey Geological Survey Report GSR-32, A Method for Evaluating Groundwater-Recharge Areas in New Jersey, incorporated herein by reference as amended and supplemented. Information regarding the methodology is available from the New Jersey Stormwater Best Management Practices Manual; at the New Jersey Geological Survey website at: https://www.nj.gov/dep/njgs/pricelst/gsreport/gsr32.pdf or at New Jersey Geological and Water Survey, 29 Arctic Parkway, PO Box 420 Mail Code 29-01, Trenton, New Jersey 08625-0420.
A. 
Site design features identified under § 138-8F, or alternative designs in accordance with § 138-8G, to prevent discharge of trash and debris from drainage systems shall comply with the following standard to control passage of solid and floatable materials through storm drain inlets. For purposes of this subsection, "solid and floatable materials" means sediment, debris, trash, and other floating, suspended, or settleable solids. For exemptions to this standard see § 138-14A(3) below.
(1) 
Design engineers shall use one of the following grates whenever they use a grate in pavement or another ground surface to collect stormwater from that surface into a storm drain or surface water body under that grate:
(a) 
The New Jersey Department of Transportation (NJDOT) bicycle safe grate, which is described in Chapter 2.4 of the NJDOT Bicycle Compatible Roadways and Bikeways Planning and Design Guidelines; or
(b) 
A different grate, if each individual clear space in that grate has an area of no more than seven square inches, or is no greater than 0.5 inch across the smallest dimension.
(2) 
For curb-opening inlets, including curb-opening inlets in combination inlets, the clear space in that curb opening, or each individual clear space if the curb opening has two or more clear spaces, shall have an area of no more than seven square inches, or be no greater than two inches across the smallest dimension.
(3) 
The standard in § 138-14A(1) above does not apply:
(a) 
Where each individual clear space in the curb opening in existing curb-opening inlet does not have an area of more than nine square inches;
(b) 
Where the municipality agrees that the standards would cause inadequate hydraulic performance that could not practicably be overcome by using additional or larger storm drain inlets;
(c) 
Where flows from the water quality design storm as specified in N.J.A.C. 7:8 are conveyed through any device (e.g., end of pipe netting facility, manufactured treatment device, or a catch basin hood) that is designed, at a minimum, to prevent delivery of all solid and floatable materials that could not pass through one of the following:
[1] 
A rectangular space 4 5/8 (4.625) inches long and 1 1/2 (1.5) inches wide (this option does not apply for outfall netting facilities); or
[2] 
A bar screen having a bar spacing of 0.5 inch.
Note that these exemptions do not authorize any infringement of requirements in the Residential Site Improvement Standards for bicycle safe grates in new residential development (N.J.A.C. 5:21-4.18(b)2 and 7.4(b)1).
(d) 
Where flows are conveyed through a trash rack that has parallel bars with one-inch spacing between the bars, to the elevation of the Water Quality Design Storm as specified in N.J.A.C. 7:8; or
(e) 
Where the New Jersey Department of Environmental Protection determines, pursuant to the New Jersey Register of Historic Places Rules at N.J.A.C. 7:4-7.2(c), that action to meet this standard is an undertaking that constitutes an encroachment or will damage or destroy the New Jersey Register listed historic property.
A. 
Technical guidance for stormwater management measures can be found in the documents listed below, which are available to download from the Department's website at: http://www.nj.gov/dep/stormwater/bmp_manual2.htm.
(1) 
Guidelines for stormwater management measures are contained in the New Jersey Stormwater Best Management Practices Manual, as amended and supplemented. Information is provided on stormwater management measures such as, but not limited to, those listed in Tables 1, 2, and 3.
(2) 
Additional maintenance guidance is available on the Department's website at: https://www.njstormwater.org/maintenance_guidance.htm.
B. 
Submissions required for review by the Department should be mailed to: The Division of Water Quality, New Jersey Department of Environmental Protection, Mail Code 401-02B, PO Box 420, Trenton, New Jersey 08625-0420.
This section sets forth requirements to protect public safety through the proper design and operation of stormwater management BMPs. This section applies to any new stormwater management BMP.
A. 
The provisions of this section are not intended to preempt more stringent municipal or county safety requirements for new or existing stormwater management BMPs. Municipal and county stormwater management plans and ordinances may, pursuant to their authority, require existing stormwater management BMPs to be retrofitted to meet one or more of the safety standards in Subsection B below for trash racks, overflow grates, and escape provisions at outlet structures.
B. 
Requirements for trash racks, overflow grates and escape provisions.
(1) 
A trash rack is a device designed to catch trash and debris and prevent the clogging of outlet structures. Trash racks shall be installed at the intake to the outlet from the stormwater management BMP to ensure proper functioning of the BMP outlets in accordance with the following:
(a) 
The trash rack shall have parallel bars, with no greater than six-inch spacing between the bars;
(b) 
The trash rack shall be designed so as not to adversely affect the hydraulic performance of the outlet pipe or structure;
(c) 
The average velocity of flow through a clean trash rack is not to exceed 2.5 feet per second under the full range of stage and discharge. Velocity is to be computed on the basis of the net area of opening through the rack; and
(d) 
The trash rack shall be constructed of rigid, durable, and corrosion resistant material and designed to withstand a perpendicular live loading of 300 pounds per square foot.
(2) 
An overflow grate is designed to prevent obstruction of the overflow structure. If an outlet structure has an overflow grate, such grate shall meet the following requirements:
(a) 
The overflow grate shall be secured to the outlet structure but removable for emergencies and maintenance;
(b) 
The overflow grate spacing shall be no less than two inches across the smallest dimension; and
(c) 
The overflow grate shall be constructed and installed to be rigid, durable, and corrosion-resistant, and shall be designed to withstand a perpendicular live loading of 300 pounds per square foot.
(3) 
Stormwater management BMPs shall include escape provisions as follows:
(a) 
If a stormwater management BMP has an outlet structure, escape provisions shall be incorporated in or on the structure. Escape provisions include the installation of permanent ladders, steps, rungs, or other features that provide easily accessible means of egress from stormwater management BMPs. With the prior approval of the municipality pursuant to § 138-16B, a freestanding outlet structure may be exempted from this requirement;
(b) 
Safety ledges shall be constructed on the slopes of all new stormwater management BMPs having a permanent pool of water deeper than 2 1/2 feet. Safety ledges shall be comprised of two steps. Each step shall be four to six feet in width. One step shall be located approximately 2 1/2 feet below the permanent water surface, and the second step shall be located one to 1 1/2 feet above the permanent water surface. See § 138-16D below for an illustration of safety ledges in a stormwater management BMP; and
(c) 
In new stormwater management BMPs, the maximum interior slope for an earthen dam, embankment, or berm shall not be steeper than three horizontal to one vertical.
C. 
Variance or exemption from safety standard. A variance or exemption from the safety standards for stormwater management BMPs may be granted only upon a written finding by the municipality that the variance or exemption will not constitute a threat to public safety.
D. 
Safety ledge illustration.
Elevation View-Basin Safety Ledge Configuration
138Elevation view.tif
A. 
Submission of site development stormwater plan.
(1) 
Whenever an applicant seeks municipal approval of a development subject to this chapter, the applicant shall submit all of the required components of the Checklist for the Site Development Stormwater Plan at § 138-17C below as part of the submission of the application for approval.
(2) 
The applicant shall demonstrate that the project meets the standards set forth in this chapter.
(3) 
The applicant shall submit five copies of the materials listed in the checklist for site development stormwater plans in accordance with § 138-17C below.
B. 
Site development stormwater plan approval. The applicant's site development project shall be reviewed as a part of the review process by the municipal board or official from which municipal approval is sought. That municipal board or official shall consult the municipality's review engineer to determine if all of the checklist requirements have been satisfied and to determine if the project meets the standards set forth in this chapter.
C. 
Submission of site development stormwater plan. The following information shall be required:
(1) 
Topographic base map. The reviewing engineer may require upstream tributary drainage system information as necessary. It is recommended that the topographic base map of the site be submitted which extends a minimum of 200 feet beyond the limits of the proposed development, at a scale of one inch equals 200 feet or greater, showing two-foot contour intervals. The map as appropriate may indicate the following: existing surface water drainage, shorelines, steep slopes, soils, erodible soils, perennial or intermittent streams that drain into or upstream of the Category One waters, wetlands and floodplains along with their appropriate buffer strips, marshlands and other wetlands, pervious or vegetative surfaces, existing man-made structures, roads, bearing and distances of property lines, and significant natural and manmade features not otherwise shown.
(2) 
Environmental site analysis. A written and graphic description of the natural and man-made features of the site and its surroundings should be submitted. This description should include a discussion of soil conditions, slopes, wetlands, waterways and vegetation on the site. Particular attention should be given to unique, unusual, or environmentally sensitive features and to those that provide particular opportunities or constraints for development.
(3) 
Project description and site plans. A map (or maps) at the scale of the topographical base map indicating the location of existing and proposed buildings, roads, parking areas, utilities, structural facilities for stormwater management and sediment control, and other permanent structures. The map(s) shall also clearly show areas where alterations will occur in the natural terrain and cover, including lawns and other landscaping, and seasonal high groundwater elevations. A written description of the site plan and justification for proposed changes in natural conditions shall also be provided.
(4) 
Land use planning and source control plan. This plan shall provide a demonstration of how the goals and standards of §§ 138-7 through 138-13 are being met. The focus of this plan shall be to describe how the site is being developed to meet the objective of controlling groundwater recharge, stormwater quality and stormwater quantity problems at the source by land management and source controls whenever possible.
(5) 
Stormwater management facilities map. The following information, illustrated on a map of the same scale as the topographic base map, shall be included:
(a) 
Total area to be disturbed, paved or built upon, proposed surface contours, land area to be occupied by the stormwater management facilities and the type of vegetation thereon, and details of the proposed plan to control and dispose of stormwater.
(b) 
Details of all stormwater management facility designs, during and after construction, including discharge provisions, discharge capacity for each outlet at different levels of detention and emergency spillway provisions with maximum discharge capacity of each spillway.
(6) 
Calculations.
(a) 
Comprehensive hydrologic and hydraulic design calculations for the predevelopment and post-development conditions for the design storms specified in §§ 138-8 through 138-12 of this chapter.
(b) 
When the proposed stormwater management control measures depend on the hydrologic properties of soils or require certain separation from the seasonal high water table, then a soils report shall be submitted. The soils report shall be based on on-site boring logs or soil pit profiles. The number and location of required soil borings or soil pits shall be determined based on what is needed to determine the suitability and distribution of soils present at the location of the control measure.
(7) 
Maintenance and repair plan. The design and planning of the stormwater management facility shall meet the maintenance requirements of § 138-18.
(8) 
Waiver from submission requirements. The municipal official or board reviewing an application under this chapter may, in consultation with the municipality's review engineer, waive submission of any of the requirements in § 138-17C(1) through § 138-17C(6) of this section when it can be demonstrated that the information requested is impossible to obtain or it would create a hardship on the applicant to obtain and its absence will not materially affect the review process.