Best
Management Practices Manual
Model
Stormwater Control
Ordinance for Municipalities
Section 1: Scope and Purpose
A. Policy Statement
Flood control,
groundwater recharge, and pollutant reduction through nonstructural or low
impact techniques shall be explored before relying on structural BMPs.
Structural BMPs should be integrated with nonstructural stormwater management
strategies and proper maintenance plans. Nonstructural strategies include both
environmentally sensitive site design and source controls that prevent
pollutants from being placed on the site or from being exposed to stormwater.
Source control plans should be developed based upon physical site conditions
and the origin, nature, and the anticipated quantity or amount of potential
pollutants. Multiple stormwater management BMPs may be necessary to achieve the
established performance standards for water quality, quantity, and groundwater
recharge.
Note: Municipalities are encouraged to participate in the
development of regional stormwater management plans, and to adopt and implement
ordinances for specific drainage area performance standards that address local
stormwater management and environmental characteristics.
B. Purpose
It is the purpose of
this ordinance to establish minimum stormwater management requirements and
controls for “major development,” as defined in Section 2.
C. Applicability
1. This ordinance shall
be applicable to all site plans and subdivisions for the following major
developments that require preliminary or final site plan or subdivision review:
a.
Non-residential
major developments; and
b.
Aspects
of residential major developments that are not pre-empted by the Residential
Site Improvement Standards at N.J.A.C. 5:21.
2. This ordinance shall
also be applicable to all major developments undertaken by [insert name of municipality].
D. Compatibility with
Other Permit and Ordinance Requirements
Development approvals
issued for subdivisions and site plans pursuant to this ordinance are to be
considered an integral part of development approvals under the subdivision and
site plan review process and do not relieve the applicant of the responsibility
to secure required permits or approvals for activities regulated by any other
applicable code, rule, act, or ordinance. In their interpretation and
application, the provisions of this ordinance shall be held to be the minimum
requirements for the promotion of the public health, safety, and general
welfare. This ordinance is not intended to interfere with, abrogate, or annul
any other ordinances, rule or regulation, statute, or other provision of law
except that, where any provision of this ordinance imposes restrictions
different from those imposed by any other ordinance, rule or regulation, or
other provision of law, the more restrictive provisions or higher standards
shall control.
Section 2: Definitions
Unless specifically
defined below, words or phrases used in this ordinance shall be interpreted so
as to give them the meaning they have in common usage and to give this
ordinance its most reasonable application. The definitions below are the same
as or based on the corresponding definitions in the Stormwater Management Rules
at N.J.A.C. 7:8-1.2.
“CAFRA Planning Map”
means the geographic depiction of the boundaries for Coastal Planning Areas,
“
“Compaction” means the
increase in soil bulk density.
“Core” means a
pedestrian-oriented area of commercial and civic uses serving the surrounding
municipality, generally including housing and access to public transportation.
“County review agency”
means an agency designated by the
A county planning
agency; or
A county water resource
association created under N.J.S.A 58:16A-55.5, if the ordinance or resolution
delegates authority to approve, conditionally approve, or disapprove municipal
stormwater management plans and implementing ordinances.
“Department”
means the New Jersey Department of Environmental Protection.
“Designated Center”
means a State Development and
“Design engineer” means
a person professionally qualified and duly licensed in
“Development” means the
division of a parcel of land into two or more parcels, the construction,
reconstruction, conversion, structural alteration, relocation or enlargement of
any building or structure, any mining excavation or landfill, and any use or
change in the use of any building or other structure, or land or extension of
use of land, by any person, for which permission is required under the
Municipal Land Use Law , N.J.S.A. 40:55D-1 et seq. In the case of development
of agricultural lands, development means: any activity that requires a State
permit; any activity reviewed by the County Agricultural Board (CAB) and the
State Agricultural Development Committee (SADC), and municipal review of any
activity not exempted by the Right to Farm Act , N.J.S.A 4:1C-1 et seq.
“Drainage area” means a
geographic area within which stormwater, sediments, or dissolved materials
drain to a particular receiving waterbody or to a particular point along a
receiving waterbody.
“Environmentally
critical areas” means an area or feature which is of significant environmental
value, including but not limited to: stream corridors; natural heritage
priority sites; habitat of endangered or threatened species; large areas of
contiguous open space or upland forest; steep slopes; and well head protection
and groundwater recharge areas. Habitats of endangered or threatened species
are identified using the Department’s Landscape Project as approved by the
Department’s Endangered and Nongame Species Program.
“Empowerment
Neighborhood” means a neighborhood designated by the Urban Coordinating Council
“in consultation and conjunction with” the New Jersey Redevelopment Authority
pursuant to N.J.S.A 55:19-69.
“Erosion” means the
detachment and movement of soil or rock fragments by water, wind, ice or
gravity.
“Impervious surface”
means a surface that has been covered with a layer of material so that it is
highly resistant to infiltration by water.
“Infiltration” is the
process by which water seeps into the soil from precipitation.
“Major development”
means any “development” that provides for ultimately disturbing one or more
acres of land. Disturbance for the purpose of this rule is the placement of
impervious surface or exposure and/or movement of soil or bedrock or clearing,
cutting, or removing of vegetation.
“Municipality” means any
city, borough, town, township, or village.
“Node” means an area
designated by the State Planning Commission concentrating facilities and
activities which are not organized in a compact form.
“Nutrient” means a
chemical element or compound, such as nitrogen or phosphorus, which is
essential to and promotes the development of organisms.
“Person” means any
individual, corporation, company, partnership, firm, association, [insert name of municipality], or
political subdivision of this State subject to municipal jurisdiction pursuant
to the Municipal Land Use Law , N.J.S.A. 40:55D-1 et seq.
“Pollutant” means any
dredged spoil, solid waste, incinerator residue, filter backwash, sewage,
garbage, refuse, oil, grease, sewage sludge, munitions, chemical wastes,
biological materials, medical wastes, radioactive substance (except those
regulated under the Atomic Energy Act of 1954, as amended (42 U.S.C. 2011 et
seq.), thermal waste, wrecked or discarded equipment, rock, sand, cellar dirt,
industrial, municipal, agricultural, and construction waste or runoff, or other
residue discharged directly or indirectly to the land, ground waters or surface
waters of the State, or to a domestic treatment works. “Pollutant” includes
both hazardous and nonhazardous pollutants.
“Recharge” means the
amount of water from precipitation that infiltrates into the ground and is not
evapotranspired.
“Sediment” means solid
material, mineral or organic, that is in suspension, is being transported, or
has been moved from its site of origin by air, water or gravity as a product of
erosion.
“Site” means the lot or
lots upon which a major development is to occur or has occurred.
“Soil” means all
unconsolidated mineral and organic material of any origin.
“State Development and
Redevelopment Plan Metropolitan Planning Area (PA1)” means an area delineated
on the State Plan Policy Map and adopted by the State Planning Commission that
is intended to be the focus for much of the state’s future redevelopment and
revitalization efforts.
“State Plan Policy Map”
is defined as the geographic application of the State Development and
Redevelopment Plan’s goals and statewide policies, and the official map of
these goals and policies.
“Stormwater” means water
resulting from precipitation (including rain and snow) that runs off the land’s
surface, is transmitted to the subsurface, or is captured by separate storm
sewers or other sewage or drainage facilities, or conveyed by snow removal
equipment.
“Stormwater runoff”
means water flow on the surface of the ground or in storm sewers, resulting
from precipitation.
“Stormwater management
basin” means an excavation or embankment and related areas designed to retain
stormwater runoff. A stormwater management basin may either be normally dry
(that is, a detention basin or infiltration basin), retain water in a permanent
pool (a retention basin), or be planted mainly with wetland vegetation (most
constructed stormwater wetlands).
“Stormwater management
measure” means any structural or nonstructural strategy, practice, technology,
process, program, or other method intended to control or reduce stormwater
runoff and associated pollutants, or to induce or control the infiltration or
groundwater recharge of stormwater or to eliminate illicit or illegal
non-stormwater discharges into stormwater conveyances.
“Tidal Flood Hazard
Area” means a flood hazard area, which may be influenced by stormwater runoff
from inland areas, but which is primarily caused by the
“Urban Coordinating
Council Empowerment Neighborhood” means a neighborhood given priority access to
State resources through the New Jersey Redevelopment Authority.
“Urban Enterprise Zones”
means a zone designated by the New Jersey Enterprise Zone Authority pursuant to
the New Jersey Urban Enterprise Zones Act, N.J.S.A. 52:27H-60 et. seq.
“Urban Redevelopment
Area” is defined as previously developed portions of areas:
(1) Delineated on the State Plan Policy
Map (SPPM) as the Metropolitan Planning Area (PA1), Designated Centers, Cores
or Nodes;
(2) Designated as
(3) Designated as Urban Enterprise
Zones; and
(4) Designated as Urban Coordinating
Council Empowerment Neighborhoods.
“Waters of the State”
means the ocean and its estuaries, all springs, streams, wetlands, and bodies
of surface or ground water, whether natural or artificial, within the
boundaries of the State of New Jersey or subject to its jurisdiction.
“Wetlands” or “wetland”
means an area that is inundated or saturated by surface water or ground water
at a frequency and duration sufficient to support, and that under normal
circumstances does support, a prevalence of vegetation typically adapted for
life in saturated soil conditions, commonly known as hydrophytic vegetation.
Section 3: General Standards
A. Design and
Performance Standards for Stormwater Management Measures
1. Stormwater management measures for major
development shall be developed to meet the erosion control, groundwater
recharge, stormwater runoff quantity, and stormwater runoff quality standards
in Section 4. To the maximum extent practicable, these standards shall be met
by incorporating nonstructural stormwater management strategies into the
design. If these strategies alone are not sufficient to meet these standards,
structural stormwater management measures necessary to meet these standards
shall be incorporated into the design.
2. The standards in this ordinance 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. The standards do not apply to new major
development to the extent that alternative design and performance standards are
applicable under a regional stormwater management plan or Water Quality
Management Plan adopted in accordance with Department rules.
Note: Alternative standards shall provide at least as much
protection from stormwater-related loss of groundwater recharge, stormwater
quantity and water quality impacts of major development projects as would be
provided under the standards in N.J.A.C. 7:8-5.
Section 4: Stormwater Management Requirements for Major
Development
A. The development shall
incorporate a maintenance plan for the stormwater management measures
incorporated into the design of a major development in accordance with Section
10.
B. Stormwater management
measures shall avoid adverse impacts of concentrated flow on habitat for
threatened and endangered species as documented in the Department’ Landscape
Project or Natural Heritage Database established under N.J.S.A. 13:1B-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 quantity, and stormwater runoff quality requirements of Sections 4.F and
4.G:
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 groundwater recharge, stormwater runoff quantity, and
stormwater runoff quality requirements of Sections 4.F and 4.G 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 nonstructural and structural
stormwater management strategies and measures, the option selected complies
with the requirements of Sections 4.F and 4.G to the maximum extent
practicable;
3. The applicant demonstrates that, in order to
meet the requirements of Sections 4.F and 4.G, 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 Sections 4.F and 4.G
that were not achievable on-site.
E. Nonstructural
Stormwater Management Strategies
1. To the maximum extent
practicable, the standards in Sections 4.F and 4.G shall be met by
incorporating nonstructural stormwater management strategies set forth at
Section 4.E into the design. The applicant shall identify the nonstructural
measures incorporated into the design of the project. If the applicant contends
that it is not feasible for engineering, environmental, or safety reasons to
incorporate any nonstructural stormwater management measures identified in
Paragraph 2 below into the design of a particular project, the applicant shall
identify the strategy considered and provide a basis for the contention.
2. Nonstructural stormwater management strategies
incorporated into site design shall:
a. Protect areas that
provide water quality benefits or areas particularly susceptible to erosion and
sediment loss;
b. Minimize impervious
surfaces and break up or disconnect the flow of runoff over impervious
surfaces;
c. Maximize the
protection of natural drainage features and vegetation;
d. Minimize the decrease
in the "time of concentration” from pre-construction to post construction.
"Time of concentration" is defined as the time it takes for runoff to
travel from the hydraulically most distant point of the watershed to the point
of interest within a watershed;
e. Minimize land
disturbance including clearing and grading;
f. Minimize soil
compaction;
g. Provide
low-maintenance landscaping that encourages retention and planting of native
vegetation and minimizes the use of lawns, fertilizers and pesticides;
h. Provide vegetated
open-channel conveyance systems discharging into and through stable vegetated
areas;
i. Provide other source controls to prevent or
minimize the use or exposure of pollutants at the site, in order to prevent or
minimize the release of those pollutants into stormwater runoff. Such source
controls include, but are not limited to:
(1) Site design features that help to prevent
accumulation of trash and debris in drainage systems, including features that
satisfy Section 4.E.3. below;
(2) Site design features that help to prevent
discharge of trash and debris from drainage systems;
(3) Site design features that help to prevent
and/or contain spills or other harmful accumulations of pollutants at
industrial or commercial developments; and
(4) When establishing
vegetation after land disturbance, applying fertilizer in accordance with the
requirements established under the Soil Erosion and Sediment Control Act,
N.J.S.A. 4:24-39 et seq., and implementing rules.
3. Site design features identified under Section
4.E.2.i.(2) above shall comply with the following standard to control passage
of solid and floatable materials through storm drain inlets. For purposes of
this paragraph, “solid and floatable materials” means sediment, debris, trash,
and other floating, suspended, or settleable solids. For exemptions to this
standard see Section 4.E.3.c below.
a. Design engineers shall use either 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:
(1) 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 (April
1996); or
(2) A different grate, if each individual clear
space in that grate has an area of no more than seven (7.0) square inches, or
is no greater than 0.5 inches across the smallest dimension.
Examples
of grates subject to this standard include grates in grate inlets, the grate
portion (non-curb-opening portion) of combination inlets, grates on storm sewer
manholes, ditch grates, trench grates, and grates of spacer bars in slotted
drains. Examples of ground surfaces include surfaces of roads (including
bridges), driveways, parking areas, bikeways, plazas, sidewalks, lawns, fields,
open channels, and stormwater basin floors.
b. Whenever design engineers use a curb-opening
inlet, 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 (7.0) square inches, or be no greater than two (2.0) inches across
the smallest dimension.
c. This standard does not apply:
(1) Where the review agency determines that this
standard would cause inadequate hydraulic performance that could not
practicably be overcome by using additional or larger storm drain inlets that
meet these standards;
(2) Where flows from the water quality design
storm as specified in Section 4.G.1 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:
(a) A rectangular space four and five-eighths
inches long and one and one-half inches wide (this option does not apply for
outfall netting facilities); or
(b) A bar screen having a bar spacing of 0.5
inches.
(3) Where flows are conveyed through a trash rack
that has parallel bars with one-inch (1”) spacing between the bars, to the
elevation of the water quality design storm as specified in Section 4.G.1; or
(4) 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.
4. Any land area used as
a nonstructural stormwater management measure to meet the performance standards
in Sections 4.F and 4.G shall be dedicated to a government agency, subjected to
a conservation restriction filed with the appropriate County Clerk’s office, or
subject to an approved equivalent restriction that ensures that measure or an
equivalent stormwater management measure approved by the reviewing agency is
maintained in perpetuity.
5. Guidance for nonstructural stormwater
management strategies is available in the New Jersey Stormwater Best Management
Practices Manual. The BMP Manual may be obtained from the address identified in
Section 7, or found on the Department’s website at www.njstormwater.org.
F. Erosion Control,
Groundwater Recharge and Runoff Quantity Standards
1. This subsection contains minimum design and
performance standards to control erosion, encourage and control infiltration
and groundwater recharge, and control stormwater runoff quantity impacts of
major development.
a. The minimum design and performance standards
for erosion control are those established under the Soil Erosion and Sediment
Control Act, N.J.S.A. 4:24-39 et seq. and implementing rules.
b. The minimum design and performance standards
for groundwater recharge are as follows:
(1) The design engineer shall, using the
assumptions and factors for stormwater runoff and groundwater recharge
calculations at Section 5, either:
(a) Demonstrate through hydrologic and hydraulic
analysis that the site and its stormwater management measures maintain 100
percent of the average annual pre-construction groundwater recharge volume for
the site; or
(b) Demonstrate through hydrologic and hydraulic
analysis that the increase of stormwater runoff volume from pre-construction to
post-construction for the 2-year storm is infiltrated.
(2) This groundwater recharge requirement does not
apply to projects within the “urban redevelopment area,” or to projects subject
to (3) below.
(3) The following types of stormwater shall not be
recharged:
(a) 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
(b) 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.
(4) 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.
c. In order to control stormwater runoff quantity
impacts, the design engineer shall, using the assumptions and factors for stormwater
runoff calculations at Section 5, 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, 10, 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,
10, 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 2, 10 and 100 year storm events
are 50, 75 and 80 percent, 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. The percentages shall not be
applied to post-construction stormwater runoff into tidal flood hazard areas if
the increased volume of stormwater runoff will not increase flood damages below
the point of discharge; or
(4) In tidal flood hazard areas, stormwater runoff
quantity analysis in accordance with (1), (2) and (3) above shall only be
applied if the increased volume of stormwater runoff could increase flood
damages below the point of discharge.
2. Any application for a new agricultural
development that meets the definition of major development at Section 2 shall
be submitted to the appropriate Soil Conservation District for review and
approval in accordance with the requirements of this section and any applicable
Soil Conservation District guidelines for stormwater runoff quantity and
erosion control. For the 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 manufacturing of agriculturally related
products.
G. Stormwater Runoff
Quality Standards
1. Stormwater management measures shall be
designed to reduce the post-construction load of total suspended solids (TSS)
in stormwater runoff by 80 percent of the anticipated load from the developed
site, expressed as an annual average. Stormwater management measures shall only
be required for water quality control if an additional 1/4 acre of impervious
surface is being proposed on a development site. 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 Pollution
Discharge Elimination System (NJPDES) rules, N.J.A.C. 7:14A, or in a discharge
specifically exempt under a NJPDES permit from this requirement. 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 1. The calculation of the volume of
runoff may take into account the implementation of non-structural and
structural stormwater management measures.
Table 1: Water Quality Design Storm
Distribution |
|||
|
Time |
Cumulative |
Time |
Cumulative |
|
0 |
0.0000 |
65 |
0.8917 |
|
5 |
0.0083 |
70 |
0.9917 |
|
10 |
0.0166 |
75 |
1.0500 |
|
15 |
0.0250 |
80 |
1.0840 |
|
20 |
0.0500 |
85 |
1.1170 |
|
25 |
0.0750 |
90 |
1.1500 |
|
30 |
0.1000 |
95 |
1.1750 |
|
35 |
0.1330 |
100 |
1.2000 |
|
40 |
0.1660 |
105 |
1.2250 |
|
45 |
0.2000 |
110 |
1.2334 |
|
50 |
0.2583 |
115 |
1.2417 |
|
55 |
0.3583 |
120 |
1.2500 |
|
60 |
0.6250 |
|
|
2. For purposes of TSS
reduction calculations, Table 2 below presents the presumed removal rates for
certain BMPs designed in accordance with the New Jersey Stormwater Best
Management Practices Manual. The BMP Manual may be obtained from the address
identified in Section 7, or found on the Department’s website at www.njstormwater.org. The BMP Manual and
other sources of technical guidance are listed in Section 7. TSS reduction
shall be calculated based on the removal rates for the BMPs in Table 2 below.
Alternative removal rates and methods of calculating removal rates may be used
if the design engineer provides documentation demonstrating the capability of
these alternative rates and methods to the review agency. A copy of any
approved alternative rate or method of calculating the removal rate shall be
provided to the Department at the following address: Division of Watershed
Management, New Jersey Department of Environmental Protection,
3. If more than one BMP in series is necessary to
achieve the required 80 percent TSS reduction for a site, the applicant shall
utilize the following formula to calculate TSS reduction:
R = A + B – (AXB)/100
Where
R = total TSS percent
load removal from application of both BMPs, and
A = the TSS percent
removal rate applicable to the first BMP
B = the TSS percent
removal rate applicable to the second BMP
Table 2: TSS Removal Rates
for BMPs |
|
|
Best Management Practice |
TSS Percent Removal Rate |
|
Bioretention Systems |
90 |
|
Constructed Stormwater Wetland |
90 |
|
Extended |
40-60 |
|
Infiltration Structure |
80 |
|
Manufactured Treatment Device |
See Section 6.C |
|
Sand Filter |
80 |
|
Vegetative Filter Strip |
60-80 |
|
Wet Pond |
50-90 |
4. If there is more than one onsite drainage area,
the 80 percent TSS removal rate shall apply to each drainage area, unless the
runoff from the subareas converge on site in which case the removal rate can be
demonstrated through a calculation using a weighted average.
5. 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
nonstructural strategies and structural measures that optimize nutrient removal
while still achieving the performance standards in Sections 4.F and 4.G.
6. Additional information and examples are
contained in the New Jersey Stormwater Best Management Practices Manual, which
may be obtained from the address identified in Section 7.
7. 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.
8. Special water resource protection areas shall
be established along all waters designated Category One at N.J.A.C. 7:9B, and
perennial or intermittent streams that drain into or upstream of the Category
One waters as shown on the USGS Quadrangle Maps or in the County Soil Surveys, within
the associated HUC14 drainage area. These areas shall be established for the
protection of water quality, aesthetic value, exceptional ecological
significance, exceptional recreational significance, exceptional water supply
significance, and exceptional fisheries significance of those established
Category One waters. These areas shall be designated and protected as follows:
a. The applicant shall
preserve and maintain a special water resource protection area in accordance
with one of the following:
(1) A 300-foot special water resource protection
area shall be provided on each side of the waterway, measured perpendicular to
the waterway from the top of the bank outwards or from the centerline of the
waterway where the bank is not defined, consisting of existing vegetation or
vegetation allowed to follow natural succession is provided. (2) Encroachment within the designated special
water resource protection area under Subsection (1) above shall only be allowed
where previous development or disturbance has occurred (for example, active
agricultural use, parking area or maintained lawn area). The encroachment shall
only be allowed where applicant demonstrates that the functional value and
overall condition of the special water resource protection area will be
maintained to the maximum extent practicable. In no case shall the remaining
special water resource protection area be reduced to less than 150 feet as
measured perpendicular to the top of bank of the waterway or centerline of the
waterway where the bank is undefined. All encroachments proposed under this
subparagraph shall be subject to review and approval by the Department.
b. All stormwater shall be discharged outside of
and flow through the special water resource protection area and shall comply
with the Standard for Off-Site Stability in the “Standards For Soil Erosion and
Sediment Control in New Jersey,” established under the Soil Erosion and
Sediment Control Act , N.J.S.A. 4:24-39 et seq.
c. If stormwater discharged outside of and flowing
through the special water resource protection area cannot comply with the
Standard For Off-Site Stability in the “Standards for Soil Erosion and Sediment
Control in New Jersey,” established under the Soil Erosion and Sediment Control
Act , N.J.S.A. 4:24-39 et seq., then the stabilization measures in accordance
with the requirements of the above standards may be placed within the special
water resource protection area, provided that:
(1) Stabilization measures shall not be placed
within 150 feet of the Category One waterway;
(2) Stormwater associated with discharges allowed
by this section shall achieve a 95 percent TSS post-construction removal rate;
(3) Temperature shall be addressed to ensure no
impact on the receiving waterway;
(4) The encroachment shall only be allowed where
the applicant demonstrates that the functional value and overall condition of
the special water resource protection area will be maintained to the maximum
extent practicable;
(5) A conceptual project design meeting shall be
held with the appropriate Department staff and Soil Conservation District staff
to identify necessary stabilization measures; and
(6) All encroachments proposed under this section
shall be subject to review and approval by the Department.
d. A stream corridor protection plan may be
developed by a regional stormwater management planning committee as an element
of a regional stormwater management plan, or by a municipality through an
adopted municipal stormwater management plan. If a stream corridor protection
plan for a waterway subject to Section 4.G(8) has been approved by the
Department of Environmental Protection, then the provisions of the plan shall
be the applicable special water resource protection area requirements for that
waterway. A stream corridor protection plan for a waterway subject to G.8 shall
maintain or enhance the current functional value and overall condition of the
special water resource protection area as defined in G.8.a.(1) above. In no
case shall a stream corridor protection plan allow the reduction of the Special
Water Resource Protection Area to less than 150 feet as measured perpendicular
to the waterway subject to this subsection.
e. Paragraph G.8 does
not apply to the construction of one individual single family dwelling that is
not part of a larger development on a lot receiving preliminary or final
subdivision approval on or before February 2, 2004 , provided that the
construction begins on or before February 2, 2009.
Section 5: Calculation of Stormwater Runoff and Groundwater
Recharge
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 the NRCS National
Engineering Handbook Section 4 – Hydrology and Technical Release 55 – Urban
Hydrology for Small Watersheds; or
b. The Rational Method for peak flow and the
Modified Rational Method for hydrograph computations.
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 at Section 5.A.1.a and the Rational and Modified Rational
Methods at Section 5.A.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 and 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:
1.
The
New Jersey Geological Survey Report GSR-32 A Method for Evaluating Ground-Water
Recharge Areas in
Section 6: Standards for Structural Stormwater Management
Measures
A. Standards for structural stormwater
management measures are as follows:
1. Structural stormwater management measures shall
be designed to take into account the existing site conditions, including, for
example, 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. Structural 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
(1”) 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 (1/3) the
width of the diameter of the orifice or one-third (1/3) 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 Section 8.D.
3. Structural 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. At the intake to the outlet from the stormwater
management basin, the orifice size shall be a minimum of two and one-half
inches in diameter.
5. Stormwater management basins shall be designed
to meet the minimum safety standards for stormwater management basins at
Section 8.
B. Stormwater management measure
guidelines are available in the New Jersey Stormwater Best Management Practices
Manual. Other stormwater management measures may be utilized provided the
design engineer demonstrates that the proposed measure and its design will
accomplish the required water quantity, groundwater recharge and water quality
design and performance standards established by Section 4 of this ordinance.
C. Manufactured treatment devices may be
used to meet the requirements of Section 4 of this ordinance, provided the
pollutant removal rates are verified by the New Jersey Corporation for Advanced
Technology and certified by the Department.
Section 7: Sources for Technical Guidance
A. Technical guidance for stormwater
management measures can be found in the documents listed at 1 and 2 below,
which are available from Maps and Publications, New Jersey Department of
Environmental Protection, 428 East State Street, P.O. Box 420, Trenton, New
Jersey, 08625; telephone (609) 777-1038.
1. Guidelines for stormwater management measures
are contained in the New Jersey Stormwater Best Management Practices Manual, as
amended. Information is provided on stormwater management measures such as:
bioretention systems, constructed stormwater wetlands, dry wells, extended
detention basins, infiltration structures, manufactured treatment devices,
pervious paving, sand filters, vegetative filter strips, and wet ponds.
2. The New Jersey
Department of Environmental Protection Stormwater Management Facilities
Maintenance Manual, as amended.
B. Additional technical guidance for
stormwater management measures can be obtained from the following:
1. The "Standards
for Soil Erosion and Sediment Control in
2. The
3. The Soil Conservation
Districts listed in N.J.A.C. 2:90-1.3(a)4. The location, address, and telephone
number of each Soil Conservation District may be obtained from the State Soil
Conservation Committee,
Section 8: Safety Standards for Stormwater Management Basins
A. This section sets forth requirements to
protect public safety through the proper design and operation of stormwater
management basins. This section applies to any new stormwater management basin.
Note: The provisions of this section are not intended to
preempt more stringent municipal or county safety requirements for new or
existing stormwater management basins. Municipal and county stormwater management
plans and ordinances may, pursuant to their authority, require existing
stormwater management basins to be retrofitted to meet one or more of the
safety standards in Sections 8.B.1, 8.B.2, and 8.B.3 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
basin to ensure proper functioning of the basin 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.
d. The trash rack shall be constructed and
installed to be rigid, durable, and corrosion resistant, and shall be designed
to withstand a perpendicular live loading of 300 lbs/ft sq.
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.
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 lbs./ft sq.
3. For purposes of this
paragraph 3, escape provisions means the permanent installation of ladders,
steps, rungs, or other features that provide easily accessible means of egress
from stormwater management basins. Stormwater management basins shall include
escape provisions as follows:
a. If a stormwater management basin has an outlet
structure, escape provisions shall be incorporated in or on the structure. With
the prior approval of the reviewing agency identified in Section 8.C a
free-standing outlet structure may be exempted from this requirement.
b. Safety ledges shall be constructed on the
slopes of all new stormwater management basins having a permanent pool of water
deeper than two and one-half feet. Such safety ledges shall be comprised of two
steps. Each step shall be four to six feet in width. One step shall be located
approximately two and one-half feet below the permanent water surface, and the
second step shall be located one to one and one-half feet above the permanent
water surface. See Section 8.D for an illustration of safety ledges in a
stormwater management basin.
c. In new stormwater management basins, the
maximum interior slope for an earthen dam, embankment, or berm shall not be steeper
than 3 horizontal to 1 vertical.
C. Variance or Exemption
from Safety Standards
1. A variance or exemption from the safety
standards for stormwater management basins may be granted only upon a written
finding by the appropriate reviewing agency (municipality, county or
Department) that the variance or exemption will not constitute a threat to
public safety.
D. Illustration of
Safety Ledges in a New
Section 9: Requirements for a Site Development Stormwater
Plan
A. Submission of Site
Development Stormwater Plan
1. Whenever an applicant
seeks municipal approval of a development subject to this ordinance, the
applicant shall submit all of the required components of the Checklist for the
Site Development Stormwater Plan at Section 9.C below as part of the submission
of the applicant's application for subdivision or site plan approval.
2. The applicant shall
demonstrate that the project meets the standards set forth in this ordinance.
3. The applicant shall
submit [specify number] copies of the
materials listed in the checklist for site development stormwater plans in
accordance with Section 9.C of this ordinance.
B. Site Development
Stormwater Plan Approval
The applicant's Site
Development project shall be reviewed as a part of the subdivision or site plan
review process by the municipal board or official from which municipal approval
is sought. That municipal board or official shall consult the engineer retained
by the Planning and/or Zoning Board (as appropriate) to determine if all of the
checklist requirements have been satisfied and to determine if the project
meets the standards set forth in this ordinance.
C. Checklist
Requirements
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 1"=200' or greater, showing 2-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
flood plains 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 environs.
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 Plan(s)
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 occur in the natural
terrain and cover, including lawns and other landscaping, and seasonal high
ground water elevations. A written description of the site plan and
justification of proposed changes in natural conditions may also be provided.
4. Land Use Planning and
Source Control Plan
This plan shall provide
a demonstration of how the goals and standards of Sections 3 through 6 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
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 pre-development and
post-development conditions for the design storms specified in Section 4 of
this ordinance.
b. When the proposed
stormwater management control measures (e.g., infiltration basins) depends on
the hydrologic properties of soils, then a soils report shall be submitted. The
soils report shall be based on onsite 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 Section 10.
8. Waiver from
Submission Requirements
The municipal official
or board reviewing an application under this ordinance may, in consultation
with the municipal engineer, waive submission of any of the requirements in
Sections 9.C.1 through 9.C.6 of this ordinance 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.
Section 10: Maintenance and Repair
A. Applicability
1. Projects subject to
review as in Section 1.C of this ordinance shall comply with the requirements
of Sections 10.B and 10.C.
B. General Maintenance
1. The design engineer shall prepare a maintenance
plan for the stormwater management measures incorporated into the design of a
major development.
2. The maintenance plan shall contain specific
preventative maintenance tasks and schedules; cost estimates, including
estimated cost of sediment, debris, or trash removal; and the name, address,
and telephone number of the person or persons responsible for preventative and
corrective maintenance (including replacement). Maintenance guidelines for
stormwater management measures are available in the New Jersey Stormwater Best
Management Practices Manual. If the maintenance plan identifies a person other
than the developer (for example, a public agency or homeowners’ association) as
having the responsibility for maintenance, the plan shall include documentation
of such person’s agreement to assume this responsibility, or of the developer’s
obligation to dedicate a stormwater management facility to such person under an
applicable ordinance or regulation.
3. Responsibility for
maintenance shall not be assigned or transferred to the owner or tenant of an
individual property in a residential development or project, unless such owner
or tenant owns or leases the entire residential development or project.
4. If the person responsible for maintenance
identified under Section 10.B.2 above is not a public agency, the maintenance
plan and any future revisions based on Section 10.B.7 below shall be recorded
upon the deed of record for each property on which the maintenance described in
the maintenance plan must be undertaken.
5. Preventative and corrective maintenance shall
be performed to maintain the function of the stormwater management measure,
including repairs or replacement to the structure; removal of sediment, debris,
or trash; restoration of eroded areas; snow and ice removal; fence repair or
replacement; restoration of vegetation; and repair or replacement of
nonvegetated linings.
6. The person responsible for maintenance
identified under Section 10.B.2 above shall maintain a detailed log of all
preventative and corrective maintenance for the structural stormwater
management measures incorporated into the design of the development, including
a record of all inspections and copies of all maintenance-related work orders.
7. The person responsible for maintenance
identified under Section 10.B.2 above shall evaluate the effectiveness of the
maintenance plan at least once per year and adjust the plan and the deed as
needed.
8. The person responsible for maintenance
identified under Section 10.B.2 above shall retain and make available, upon
request by any public entity with administrative, health, environmental, or
safety authority over the site, the maintenance plan and the documentation
required by Sections 10.B.6 and 10.B.7 above.
9. The requirements of Sections 10.B.3 and 10.B.4
do not apply to stormwater management facilities that are dedicated to and
accepted by the municipality or another governmental agency.
(Note: It may be appropriate to delete requirements in the
maintenance and repair plan that are not applicable if the ordinance requires
the facility to be dedicated to the municipality. If the municipality does not
want to take this responsibility, the ordinance should require the posting of a
two year maintenance guarantee in accordance with N.J.S.A. 40:55D-53.
Guidelines for developing a maintenance and inspection program are provided in
the New Jersey Stormwater Best Management Practices Manual and the NJDEP Ocean
County Demonstration Study, Stormwater Management Facilities Maintenance
Manual, dated June 1989 available from the NJDEP, Watershed Management
Program.)
10. In the event that
the stormwater management facility becomes a danger to public safety or public
health, or if it is in need of maintenance or repair, the municipality shall so
notify the responsible person in writing. Upon receipt of that notice, the
responsible person shall have fourteen (14) days to effect maintenance and
repair of the facility in a manner that is approved by the municipal engineer
or his designee. The municipality, in its discretion, may extend the time
allowed for effecting maintenance and repair for good cause. If the responsible
person fails or refuses to perform such maintenance and repair, the municipality
or County may immediately proceed to do so and shall bill the cost thereof to
the responsible person.
B. Nothing in this
section shall preclude the municipality in which the major development is
located from requiring the posting of a performance or maintenance guarantee in
accordance with N.J.S.A. 40:55D-53.
Section 11: Penalties
Any person who erects,
constructs, alters, repairs, converts, maintains, or uses any building,
structure or land in violation of this ordinance shall be subject to the following
penalties: [Municipality to specify].
Section 12: Effective Date
This ordinance shall
take effect immediately upon the approval by the county review agency, or sixty
(60) days from the receipt of the ordinance by the county review agency if the
county review agency should fail to act.
Section 13: Severability
If the provisions of any
section, subsection, paragraph, subdivision, or clause of this ordinance shall
be judged invalid by a court of competent jurisdiction, such order of judgment
shall not affect or invalidate the remainder of any section, subsection, paragraph, subdivision, or
clause of this ordinance.