[Amended 12-22-1980 by Ord. No. 80-41; 10-27-1986 by Ord. No. 86-27; 4-20-1990 by Ord. No. 90-12; 4-10-2006 by Ord. No. 2006-06; 2-22-2021 by Ord. No. 2021-06; 6-24-2024 by Ord. No. 2024-14]
A.
Policy statement. Flood control, groundwater recharge, and pollutant
reduction shall be achieved through the use of stormwater management
measures, including green infrastructure Best Management Practices
("GI BMPs") and nonstructural stormwater management strategies. GI
BMPs and low-impact development (LID) should be utilized to meet the
goal of maintaining natural hydrology to reduce stormwater runoff
volume, reduce erosion, encourage infiltration and groundwater recharge,
and reduce pollution. GI BMPs and LID 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.
C.
Applicability.
(2)
This Article XXI shall also be applicable to all major developments undertaken by West Windsor Township.
(3)
An application required by ordinance pursuant to Subsection C(1) above that has been submitted and deemed complete prior to June 24, 2024, shall be subject to the stormwater management requirements in effect on June 23, 2024.
(4)
An application required by ordinance for approval pursuant to C(1)
above that has been submitted and deemed complete on or after March
2, 2021, but prior to June 24, 2024 shall be subject to the stormwater
management requirements in effect on June 23, 2024.
(5)
Notwithstanding any rule to the contrary, a major development for
any public roadway or railroad project conducted by a public transportation
entity that has determined the entity's desired concept, typically
referred to as a "preferred alternative" or reached an equivalent
milestone before July 17, 2023, shall be subject to the stormwater
management requirements in effect prior to July 17, 2023.
D.
Compatibility with other permit and ordinance requirements.
(1)
Development approvals issued pursuant to this Article XXI are to be considered an integral part of the development approval 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 Article XXI shall be held to be the minimum requirements for the promotion of the public health, safety, and general welfare.
(2)
This Article XXI 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 Article XXI imposes restrictions different from those imposed by any other article, rule or regulation, or other provision of law, the more restrictive provisions or higher standards shall control.
A.
No application for major development shall be approved unless the
Township Engineer or other Township review engineer has certified
to the approving authority, in writing, that:
(1)
The applicant has provided sufficient information to determine
whether or not the proposed development will conform with Township
stormwater control standards and stormwater management BMP design
criteria.
(2)
In the judgment of the Township's review engineer, the
proposed development will substantially conform with these standards
and the design criteria set forth herein.
B.
The stormwater management plans submitted shall also demonstrate
careful consideration of the general and specific concerns, values
and standards of the Township Master Plan and applicable county and
state storm drainage control programs, any Mercer County Mosquito
Commission control standards, and shall be based on environmentally
sound site planning, engineering and landscape architectural techniques.
C.
Development shall use the best available technology to minimize off-site
stormwater runoff, increase on-site infiltration, simulate natural
drainage systems and minimize off-site discharge of pollutants to
ground and surface water and encourage natural filtration functions.
These goals are best achieved through GI BMPs and nonstructural stormwater
management strategies.
D.
All development sites shall be graded to secure proper drainage away
from buildings per applicable New Jersey State building codes, and
to prevent the collection of stormwater in pools on improved surfaces
and lawn areas not specifically designed for that purpose. Sufficient
inlets, catch basins, swales and other drainage appurtenances shall
be provided to convey runoff to the stormwater management BMPs.
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 Erosion 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 Article XXI apply to major development, as defined herein, and are intended to minimize the impact of stormwater runoff on water quality and water quantity in receiving water bodies and maintain groundwater recharge. 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, the standards in this Article XXI do not apply to major development. 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.
For the purpose of this Article XXI, the following terms, phrases, words and their derivations shall have the meanings stated herein unless their use in the text of this article clearly demonstrates a different meaning. When not inconsistent with the context, words used in the present tense include the future, words used in the plural number include the singular number, and words used in the singular number include the plural number. The word "shall" is always mandatory and not merely directory. 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.
A strategy or technique to prevent or mitigate one or more
of the negative impacts of stormwater runoff. BMPs can be nonstructural
or structural.
The increase in soil bulk density.
The area from which stormwater runoff drains to a stormwater
management measure, not including the area of the stormwater management
measure itself.
A pedestrian-oriented area of commercial and civic uses serving
the surrounding municipality, generally including housing and access
to public transportation.
An agency designated by the Mercer County Board of County
Commissioners to review municipal stormwater management plans and
implementing ordinance(s). The County review agency may either be:
The New Jersey Department of Environmental Protection or
NJDEP.
A person professionally qualified and duly licensed in New
Jersey to perform engineering services that may include, but not necessarily
be limited to, development of project requirements, creation and development
of project design and preparation of drawings and specifications.
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, for which
permission is required under the Municipal Land Use Law, N.J.S.A.
40:55D-1 et seq.
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In the case of development of agricultural land, "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.
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An impervious surface that directs stormwater runoff to a
pervious surface or BMP, and is not directly connected to a drainage
system either on the surface or subsurface.
The placement or reconstruction of impervious surface or
motor vehicle surface, or exposure and/or movement of soil or bedrock
or clearing, cutting, or removing of vegetation. Milling and repaving
is not considered disturbance for the purposes of this definition.
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.
The following areas where the physical alteration of the
land is in some way restricted, either through regulation, easement,
deed restriction or ownership such as: wetlands, floodplains, threatened
and endangered species sites or designated habitats, and parks and
preserves. 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.
An area or feature which is of significant environmental
value, including but not limited to: stream corridors, natural heritage
priority sites, habitats 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.
The detachment and movement of soil or rock fragments by
water, wind, ice, or gravity.
A stormwater management measure that manages stormwater close
to its source by:
An area within which water drains to a particular receiving
surface water body, also known as a subwatershed, which is identified
by a fourteen-digit hydrologic unit boundary designation, delineated
within New Jersey by the United States Geological Survey.
A surface that has been sufficiently compacted or covered
with a layer of material so that it is highly resistant to infiltration
by water.
Is the process by which water from precipitation moves into
the soil.
One or more public entities having stormwater management
planning authority designated by the regional stormwater management
planning committee pursuant to N.J.A.C. 7:8-3.2, that serves as the
primary representative of the committee.
Development that includes strategies, practices and techniques
that preserve, make use of, or mimic natural processes that result
in the infiltration, evapotranspiration or use of stormwater in order
to protect water quality and associated aquatic habitat.
Any development or redevelopment, as defined by this section,
that individually or collectively results in the disturbance of one
or more acres of land since February 2, 2004;
Major development includes all developments that are part
of a common plan of development or sale (for example, phased residential
development) that collectively or individually result in the disturbance
of one or more acres of land since February 2, 2004. Projects undertaken
by any government agency that otherwise meet the definition of "major
development" but which do not require approval under the Municipal
Land Use Law, N.J.S.A. 40:55D-1 et seq., are also considered "major
development."
Land vehicles propelled other than by muscular power, such
as automobiles, motorcycles, autocycles, and low speed vehicles. For
the purposes of this definition, motor vehicle does not include farm
equipment, snowmobiles, all-terrain vehicles, motorized wheelchairs,
go-carts, gas buggies, golf carts, ski-slope grooming machines, or
vehicles that run only on rails or tracks.
Any pervious or impervious surface that is intended to be
used by "motor vehicles" and/or aircraft, and is directly exposed
to precipitation including, but not limited to, driveways, parking
areas, parking garages, roads, racetracks, and runways.
Any city, borough, town, township, or village; in this article
it is West Windsor Township.
The manual maintained by the Department providing, in part,
design specifications, removal rates, calculation methods, and soil
testing procedures approved by the Department as being capable of
contributing to the achievement of the stormwater management standards
specified in this article.
The BMP Manual is periodically amended by the Department
as necessary to provide design specifications on additional best management
practices and new information on already included practices, reflecting
the best available current information regarding the particular practice
and the Department's determination as to the ability of that
best management practice to contribute to compliance with the standards
contained in this article.
An area designated by the State Planning Commission concentrating
facilities and activities which are not organized in a compact form.
A chemical element or compound, such as nitrogen or phosphorus,
which is essential to and promotes the development of organisms.
Flow of water through soil and porous or fractured rock or
other media.
Any individual, corporation, company, partnership, firm,
association, political subdivision of this state and any state, interstate
or federal agency.
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 materials.
A pathway for use by motor vehicles or trains that is intended
for public use and is constructed by, or on behalf of, a public transportation
entity. A public roadway or railroad does not include a roadway or
railroad constructed as part of a private development, regardless
of whether the roadway or railroad is ultimately to be dedicated to
and/or maintained by a governmental entity.
A federal, state, county, or municipal government, an independent
state authority, or a statutorily authorized public-private partnership
program pursuant to P.L. 2018, c. 90 (N.J.S.A. 40A:11-52 et seq.),
that performs a public roadway or railroad project that includes new
construction, expansion, reconstruction, or improvement of a public
roadway or railroad.
The process by which water is added to groundwater aquifers;
the volume of water from precipitation that infiltrates into the ground
below the root zone and is not lost to evapotranspiration.
Land-disturbing activity that results in the creation, addition,
or replacement of impervious surface area on an already developed
or disturbed site. Redevelopment includes, but is not limited to:
the expansion of a building footprint; addition or replacement of
a structure; replacement of impervious surface area that is not part
of a routine maintenance activity; and land disturbing activities
related to structural or impervious surfaces. It does not include
routine maintenance to maintain original line and grade, hydraulic
capacity, or original purpose of facility, nor does it include emergency
construction activities required to immediately protect public health
and safety.
Any of the following, alone or in combination:
A net increase of impervious surface; and/or
The total area of impervious surface collected by a new stormwater
conveyance system (for the purpose of this definition, a "new stormwater
conveyance system" is a stormwater conveyance system that is constructed
where one did not exist immediately prior to its construction or an
existing system for which a new discharge location is created); and/or
The total area of impervious surface proposed to be newly collected
by an existing stormwater conveyance system; and/or
The total area of impervious surface collected by an existing
stormwater conveyance system where the capacity of that conveyance
system is increased.
Any of the following, alone or in combination:
The total area of motor vehicle surface that is currently receiving
precipitation; and/or
A net increase in motor vehicle surface; and/or
The total 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, where the water quality treatment will be modified or removed.
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.
Movement of water or gas through a media, typically soil.
The lot or lots upon which a major development is to occur
or has occurred.
All unconsolidated mineral and organic material of any origin.
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.
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.
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.
An excavation or embankment and related areas designed to
retain and manage release of stormwater runoff. A stormwater management
BMP may either be normally dry (that is, a detention basin or infiltration
system), retain water in a permanent pool (a retention basin), or
be planted mainly with wetland vegetation (most constructed stormwater
wetlands).
Any 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.
A public body authorized by legislation to prepare stormwater
management plans.
The geographic area for which a stormwater management planning
agency is authorized to prepare stormwater management plans, or a
specific portion of that area identified in a stormwater management
plan prepared by that agency.
Water flow on the surface of the ground or in storm sewers,
resulting from precipitation.
Is defined as previously developed portions of areas:
A structure within, or adjacent to, a water, which intentionally
or coincidentally alters the hydraulic capacity, the flood elevation
resulting from the two-, ten-, or 100-year design storm, flood hazard
area limit, and/or floodway limit of the water. Examples of a water
control structure may include a bridge, culvert, dam, embankment,
fjord (if above grade), retaining wall, and weir.
The ocean and its estuaries, all springs, streams, wetlands,
and bodies of surface or groundwater, whether natural or artificial,
within the boundaries of the State of New Jersey or subject to its
jurisdiction.
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.
A.
Stormwater management measures as may be required under the terms of this Article XXI shall be located on site and within the zoning district permitting that use, subject to the requirements outlined herein. Such measures shall be considered accessory uses and also subject to the conditions of Part 4, Zoning, of this chapter.
B.
Such stormwater management measures may be located within the setback line of the area to be improved, excluding landscape transition buffers, landscape buffers or landscape strips as may be required in Part 4, Zoning, of this chapter. A minimum offset for landscape buffers must be provided from the perimeter of sand-based surface stormwater BMPs outlined in the tables in § 200-101 as measured between the maximum water surface elevation and adjacent roads, drive aisles, bike paths, parking lots, property lines and buildings in order to facilitate conformance with the design standards at § 200-91P(4) as follows: 10 feet for small-scale sand filter and small-scale infiltration basin per § 200-101F Table 1; 30 feet for sand filter and infiltration basin per § 200-101F Table 2 and 30 feet for sand filter per § 200-101F Table 3.
Where it can be demonstrated at the time of Township land use
board review that such on-site stormwater management measure location
within the zoning district permitting that use is impractical due
to engineering feasibility factors, then the Township land use board
of jurisdiction may permit such measure to be located off-tract and/or
out of the zoning district, provided that the following requirements
are met:
B.
Location of the measure does not hinder or discourage the appropriate
development and use of the property on which it is located or the
use of adjacent land and buildings.
C.
Permanent access and easement to the measure shall be provided for
preservation and for maintenance purposes.
D.
Location of the measure shall be referenced in the deed notice required under § 200-101M and a separate deed notice shall be provided and recorded for the property upon which the measure is located.
E.
Utilization of other nearby off-tract stormwater management facilities
is not feasible or practicable as determined by the developer's
engineer, subject to confirmation by the Township Engineer.
A.
The development shall include a Maintenance Plan for the stormwater management measures incorporated into the design of a major development in accordance with § 200-105.
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. 13:1B-15.147 through 15.150, particularly
Helonias bullata (swamp pink) and/or Glyptemys muhlenbergii (bog turtle).
C.
The following linear development projects are exempt from the groundwater recharge, stormwater runoff quality, and stormwater runoff quantity requirements of § 200-101P, Q and R:
(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 § 200-101O, P, Q and R 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;
(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 Subsection D(3) above within the upstream drainage area of the receiving stream, that would provide additional opportunities to mitigate the requirements of § 200-101O, P, Q and R that were not achievable onsite.
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 § 200-101O, P, Q and R. 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. The most current version of the BMP Manual can be found on the Department's website at: https://dep.nj.gov/stormwater/bmp-manual/.
F.
Where the BMP tables in this Article XXI are different from the corresponding tables in the NJ Stormwater Management Rule N.J.A.C. 7:8-5.2(f) due to updates or amendments to N.J.A.C. 7:8-5.2(f), the BMP Tables in the Stormwater Management rule at N.J.A.C. 7:8-5.2(f) shall take precedence.
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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% to 80%
|
No
|
No
|
—
|
|
(Notes corresponding to annotations(a) through(g) are found after Table 3)
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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% to 90%
|
Yes
|
No
|
N/A
|
|
(Notes corresponding to annotations(b) through (d) are found after Table 3)
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|
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% to 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% to 90%
|
Yes
|
No
|
N/A
|
|
Notes for Tables 1, 2, and 3:
| |
|---|---|
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(a)
|
Subject to the applicable contributory drainage area limitation specified at § 200-101O(2);
|
|
(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 definition of green infrastructure at § 200-100.2;
|
|
(h)
|
Manufactured treatment devices that do not meet the definition of green infrastructure at § 200-100.2.
|
G.
Alternative measures. 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 Township. 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 New Jersey Department of Environmental Protection in accordance with § 200-101.3B.
(2)
Alternative stormwater management measures that function in a similar manner to a BMP listed at § 200-101O(2) are subject to the contributory drainage area limitation specified at § 200-101O(2) for that similarly functioning BMP.
(3)
Alternative stormwater management measures approved in accordance with this subsection that do not function in a similar manner to any BMP listed at § 200-101O(2) 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.
(4)
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 § 200-101D is granted from § 200-101O.
H.
Groundwater mounding analysis. 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 sensitive areas; wetlands; flood-prone areas; slopes;
depth to seasonal high-water table; soil type, permeability, and texture;
drainage area and drainage patterns;
(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 safety standards of § 200-103C;
(3)
Stormwater management measures and their components shall be
designed, constructed, and installed to be strong, durable, and corrosion
resistant, where required. 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 § 200-103; and
(5)
The minimum size of the orifice at the intake to the outlet
from the stormwater management BMP shall be 2 1/2 inches in diameter.
(6)
To the maximum extent practicable, the design engineer shall
design stormwater management measures that incorporate pretreatment
measures. Pretreatment can extend the functional life and increase
the pollutant removal capability of a stormwater management measure.
Pretreatment measures shall be designed in accordance with the New
Jersey BMP Manual or other sources approved by the Township Engineer.
J.
Manufactured treatment devices. Manufactured treatment devices may be used to meet the requirements of this Article, 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 § 200-100.2 may be used only under the circumstances described at § 200-101O(4) where a variance or waiver is granted.
K.
Agricultural developments. Any application for a new agricultural development that meets the definition of major development at § 200-100.2 shall be submitted to the Soil Conservation District for review and approval in accordance with the requirements at § 200-101O, P, Q and R and any applicable Soil Conservation District guidelines for stormwater runoff quantity and erosion control. For purposes of this subsection, "agricultural development" means land uses normally associated with the production of food, fiber, horticultural product 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.
Requirements by drainage area. If there is more than one drainage area involved in a major development, the groundwater recharge, stormwater runoff quality, and stormwater runoff quantity standards at § 200-101P, Q and R shall be met in each drainage area, unless the runoff from the drainage areas converge onsite 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.
Deed notice requirement. Any stormwater management measure authorized under the Township stormwater management plan or this Article XXI shall be reflected in a deed notice recorded in the Office of the Mercer County Clerk. A form of deed notice shall be submitted to the Township 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 § 200-101O, P, Q and R and shall identify the location(s) 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 § 200-105B(5) by plan title, project name, municipal project number, name, title and license information of the preparer, and latest revision date of the plan.
Prior to the commencement of construction, proof that the above
required deed notice has been filed shall be submitted to the Township.
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 Township is not a copy of the complete recorded document, a copy
of the complete recorded document shall be provided to the Township
within 180 calendar days of the authorization granted by the Township.
N.
Alterations and replacements. A stormwater management measure approved under the Township stormwater management plan or Article XXI may be altered or replaced with the approval of the Township, if the Township determines that the proposed alteration or replacement meets the design and performance standards pursuant to § 200-101 of this Article XXI 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 Township for approval and subsequently recorded with the Office of the Mercer County Clerk. The revised deed notice shall contain a description and location of the altered or replacement stormwater management measure, as well as reference to the amended or supplemental Maintenance Plan, in accordance with § 200-101M above.
Prior to the commencement of construction, proof that the above required deed notice has been filed shall be submitted to the Township in accordance with § 200-101M above.
O.
Green infrastructure standards.
(1)
This subsection specifies the types of green infrastructure
BMPs that may be used to satisfy the groundwater recharge, stormwater
runoff quality, and stormwater runoff quantity standards.
(2)
To satisfy the groundwater recharge and stormwater runoff quality standards at § 200-101P and Q, the design engineer shall utilize green infrastructure BMPs identified in Table 1 at § 200-101F and/or an alternative stormwater management measure approved in accordance with § 200-101G. 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
|
(4)
If a variance in accordance with N.J.A.C. 7:8-4.6 or a waiver from strict compliance in accordance with § 200-101D is granted from the requirements of this subsection, then BMPs from Table 1, 2, or 3, and/or an alternative stormwater management measure approved in accordance with § 200-101G may be used to meet the groundwater recharge, stormwater runoff quality, and stormwater runoff quantity standards at § 200-101P, Q and R.
P.
Groundwater recharge standards.
(1)
This subsection contains the minimum design and performance
standards for groundwater recharge as follows:
(2)
The design engineer shall, using the assumptions and factors for stormwater runoff and groundwater recharge calculations at § 200-101.1, either:
(a)
Demonstrate through hydrologic and hydraulic analysis that the
site and its stormwater management measures maintain 100% of the average
annual preconstruction groundwater recharge volume for the site; or
(b)
Demonstrate through hydrologic and hydraulic analysis that the increase of stormwater runoff volume from pre-construction to post-construction for the projected two-year storm, as defined and determined pursuant to § 200-101.1D of this article is infiltrated.
(3)
This groundwater recharge requirement does not apply to projects within the "urban redevelopment area," or to projects subject to § 200-101P(4) below.
(4)
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
approved pursuant to the Administrative Requirements for the Remediation
of Contaminated Sites rules, N.J.A.C. 7:26C, 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.
Q.
Stormwater runoff quality standards.
(1)
This subsection 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 one-quarter acre or more of
regulated motor vehicle surface.
(2)
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:
(a)
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.
(b)
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.
(3)
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 Q(2) 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.
(4)
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 5-4: Water Quality Design Storm Distribution at N.J.A.C.
7:8-5.5. The calculation of the volume of runoff may take into account
the implementation of stormwater management measures.
(5)
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
|
(6)
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 § 200-101P, Q and R.
(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)
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.
(9)
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 subsection 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.
(10)
These 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 materials
such as gravel, soil, and/or shells.
R.
Stormwater runoff quantity standards.
(1)
This subsection contains the minimum design and performance
standards to control stormwater runoff quantity impacts of major development.
(2)
In order to control stormwater runoff quantity impacts, the design engineer shall, using the assumptions and factors for stormwater runoff calculations at § 200-101.1, complete one of the following:
(a)
Demonstrate through hydrologic and hydraulic analysis that for
stormwater leaving the site, post-construction runoff hydrographs
for the current and projected two-, ten-, and 100-year storm events,
as calculated using the precipitation depths determined by the standards
found in § 101.1C and D, do not exceed, at any point in
time, the pre-construction runoff hydrographs for the same storm events;
or
(b)
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 current
and projected two-, ten- and 100-year storm events, as calculated
using the precipitation depths determined by the standards found in
§ 101.1C and D, and that the increased volume or change
in timing of stormwater runoff will not increase flood damage at or
downstream of the site. This analysis shall include the analysis of
impacts of existing land uses and projected land uses assuming full
development under existing zoning and land use ordinances in the drainage
area; or
(c)
Design stormwater management measures so that the post-construction
peak runoff rates for the current and projected two-, ten- and 100-year
storm events, as calculated using the precipitation depths determined
by the standards found in § 101.1C and D, 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.
(3)
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 the following
method: 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://directives.sc.egov.usda.gov/22162.wba,
or at United States Department of Agriculture Natural Resources Conservation
Service, 220 Davison Avenue, Somerset, New Jersey 08873;
(2)
For the purpose of calculating curve numbers 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 "curve number" applies to the NRCS methodology.
A curve number or a groundwater recharge land cover for an existing
condition differing from "wooded" land with "good" cover may be used
on all or a portion of the site if the design engineer verifies and
substantiates that the differing 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 differing
land cover has existed on the site during the five years immediately
prior to the time of application, the differing land cover with the
lowest runoff potential shall be used for the computations. The design
engineer shall presume that the site is in "good" hydrologic condition
if the differing land use type is pasture, lawn, or park; with "good"
cover if the differing land use type is woods; and with hydrologic
condition "good with conservation treatment" if the differing land
use type is cultivation.
(3)
In computing existing condition 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. In computing stormwater runoff from all design storms,
the design engineer shall determine 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 disconnected impervious surface,
urban impervious area modifications as described in the NRCS Technical
Release 55 - Urban Hydrology for Small Watersheds or other methods
acceptable to the Township Engineer may be employed.
(4)
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 stormwater management measures.
B.
Groundwater recharge. 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/nigs/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.
C.
Current precipitation depths. The precipitation depths of the current two-, ten-, and 100-year storm events shall be determined by multiplying the values determined in accordance with Subsection C(1) and (2) below:
(1)
The applicant shall utilize the National Oceanographic and Atmospheric
Administration (NOAA), National Weather Service's Atlas 14 Point
Precipitation Frequency Estimates: NJ, in accordance with the location(s)
of the drainage area(s) of the site. This data is available at: https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html?bkmrk=nj;
and
(2)
The applicant shall utilize the following values from Table
5-5: Current Precipitation Adjustment Factors found under N.J.A.C.
7:8-5.7(c), which sets forth the applicable multiplier for the drainage
area(s) of the site, in accordance with the county or counties where
the drainage area(s) of the site is located. Where the major development
lies in more than one county, the precipitation values shall be adjusted
according to the percentage of the drainage area in each county. Alternately,
separate rainfall totals can be developed for each county using the
values in the referenced table.
|
Table 5-5: Current Precipitation Adjustment Factors
| |||
|---|---|---|---|
|
County
|
Current Precipitation Adjustment Factors
| ||
|
2-year Design Storm
|
10-year Design Storm
|
100-year Design Storm
| |
|
Mercer
|
1.01
|
1.02
|
1.04
|
|
Middlesex
|
1.00
|
1.01
|
1.03
|
D.
Projected precipitation depths. Table 5-6: Future Precipitation Change Factors, found under N.J.A.C. 7:8-5.7(d), sets forth the change factors to be used in determining the projected two-, ten-, and 100-year storm events for use in this chapter, which are organized alphabetically by county. The precipitation depth of the projected two-, ten-, and 100-year storm events of a site shall be determined by multiplying the precipitation depth of the two-, ten-, and 100-year storm events determined from the National Weather Service's Atlas 14 Point Precipitation Frequency Estimates pursuant to Subsection C(1) above, by the change factor in the table below, in accordance with the county or counties where the drainage area(s) of the site is located. Where the major development and/or its drainage area lies in more than one county, the precipitation values shall be adjusted according to the percentage of the drainage area in each county.
|
Table 5-6: Future Precipitation Change Factors
| |||
|---|---|---|---|
|
County
|
Future Precipitation Change Factors
| ||
|
2-year Design Storm
|
10-year Design Storm
|
100-year Design Storm
| |
|
Mercer
|
1.16
|
1.17
|
1.36
|
|
Middlesex
|
1.19
|
1.21
|
1.33
|
A.
All development shall be designed to account for stormwater and natural
drainage water which originates not only within the lot or tract boundaries,
but also that originating beyond the lot or tract boundaries which
normally flows into or through the development lot or tract boundaries.
B.
Stormwater runoff, natural drainage water or water discharged from
any source shall not be so diverted or directed as to overload existing
drainage systems or create flooding or the need for additional drainage
improvements, including structures, on other private properties or
public lands. Proper and approved provisions shall be made in the
development design to relieve these conditions to the satisfaction
of the Township Engineer.
C.
Over the sidewalk, under the sidewalk and/or through the curb drains for the purpose of discharging of roof drains or sump pumps is prohibited. These facilities must outlet into an adequate watercourse or drainage conveyance or collection system as approved by the Township Engineer. Roof leaders in violation of § 200-101.2B must be connected to an approved drainage system as determined by the Township Engineer. In the absence of a practical outlet for either a sump pump or roof leader, other drainage systems, as approved by the Township Engineer, may be used.
D.
The design of any stormwater runoff collection system shall conform
to N.J.A.C. 5:21-7.2 and 7.3, except high density polyethylene pipe
(HDPE) shall not be used for any system or portion thereof to be dedicated
to West Windsor Township, or for driveway culverts. Minimum pipe size
for any public drainage system is 15 inches in diameter.
E.
The stormwater collection and conveyance system for major development
shall be analyzed for the 100-year design storm event. The temporary
maximum depth of standing water at any pavement gutter line shall
not exceed nine inches. Further, temporary standing water shall not
encroach upon any building envelope, existing or proposed. In sump
conditions, overland relief shall be provided in the form of a drainage
swale designed to carry the design flow to its intended destination.
As an alternative, the storm sewer system shall be designed for the
100-year design storm from the sump location to the stormwater BMP
discharge, and shall include adequate capacity at each inlet to admit
the 100-year design storm runoff.
F.
The materials used in the construction of storm sewers and other
drainage structures shall be in accordance with the Standard Specifications
for Road and Bridge Construction of the New Jersey Department of Transportation,
latest edition, including any supplements, addendum and modifications
thereto. "WEST WINDSOR TOWNSHIP STORM SEWER" shall be cast integrally
in the cover of any storm manhole cover. Modification or change of
these specifications may be affected only with the knowledge and written
consent of the Township Engineer.
G.
Minimum overland grades on all lots shall not be designed at less
than a 2% slope unless within a designed waterway, stormwater management
facility or structural pavement area. Maximum grades shall not exceed
a ratio of 3 horizontal to 1 vertical. Wherever possible, all lots
without an on-lot stormwater management facility or collection structure
shall be designed to provide positive drainage to the roadway facility
fronting the same without flowing onto or across adjacent property.
I.
Approval for drainage structures shall also be obtained from the
appropriate West Windsor, Mercer County, State of New Jersey and Federal
agencies and offices. Each applicant shall make application to the
Department of Environmental Protection, the Delaware & Raritan
Canal Commission, the Mercer County Engineering Department and the
Township Engineer, as applicable. Letters of approval from the appropriate
governmental authorities shall be furnished to the Township Engineer,
with copies to the administrative officer, prior to the granting of
final approval or, if approval is granted conditionally, letters of
approval shall be provided prior to the Township Engineer's signing
of the final map or final plans.
J.
Where required by the Township, if a lot or tract is traversed by
a watercourse, surface or underground drainageway or drainage system,
channel or stream, there shall be provided and dedicated a drainage
easement to the Township, or other owners of the private drainage
systems, conforming substantially with the lines of such watercourse
or drainage system and such further width as will be adequate to accommodate
expected stormwater runoff in the future, based upon reasonable growth
potential in the Township, and in any event, meeting any minimum widths
and locations shown on any adopted Official Map or Master Plan. Such
easement dedication shall be expressed on the plan and plat as follows:
"Drainage easement granted to {insert owner, party or entity} for
the purposes provided for and expressed in the Code of the Township
of West Windsor." The Township shall have the right, but not the obligation,
to inspect, maintain, repair and replace the conveyance system.
K.
If the potential for contamination of stormwater runoff by petroleum
products exists on-site, the stormwater runoff shall be collected
and conveyed through an oil/grease separator or other equivalent manufactured
filtering device to remove the petroleum hydrocarbons prior to discharge.
The applicant shall provide sufficient data to demonstrate acceptable
performance of the device, and maintenance of the device shall be
addressed in the development Maintenance Plan.
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: https://dep.nj.gov/stormwater/bmp-manual/
(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://dep.nj.gov/stormwater/maintenance-guidance/.
B.
Submissions required by this article for review by the Department
should be mailed to: The Division of Watershed Protection and Restoration,
New Jersey Department of Environmental Protection, Mail Code 501-02A,
PO Box 420, Trenton, New Jersey 08625-0420. Proof of mailing shall
be provided to the Township Engineer.
A.
Site design features identified under the BMP Tables at § 200-101F above, or alternative designs in accordance with § 200-101G above, in order 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 paragraph, "solid and floatable materials" means sediment, debris, trash, and other floating, suspended, or settleable solids. Exemptions to this standard are outlined in § 200-102A(2).
(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:
(i)
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
(ii)
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 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 system
floors used to collect stormwater from the surface into a storm drain
or surface water body.
(iii)
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.
(2)
The standard in § 200-102A(1) above does not apply:
(i)
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;
(ii)
Where the Township agrees that the standards would cause inadequate
hydraulic performance that could not practicably be overcome by using
additional or larger storm drain inlets;
(iii)
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:
(a)
A rectangular space 4.625 inches long and 1.5 inches
wide (this option does not apply for outfall netting facilities);
or
(b)
A bar screen having a bar spacing of 0.5 inches.
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].
(iv)
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
(v)
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.
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, modified or altered stormwater management
BMP.
B.
Stormwater management BMPs providing long-term water retention, shall be designed to be able to be dewatered, with minimal reliance on mechanical pumping, where practical. Pedestrian or vehicular traffic adjacent to these facilities should be evaluated to determine if and what safety measures or barriers should be provided in addition to safety ledges required by § 200-103C(3).
C.
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:
(i)
The trash rack shall have parallel bars, with no greater than
six-inch spacing between the bars;
(ii)
The trash rack shall be designed so as not to adversely affect
the hydraulic performance of the outlet pipe or structure;
(iii)
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
(iv)
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:
(i)
The overflow grate shall be secured to the outlet structure
but removable for emergencies and maintenance.
(ii)
The overflow grate spacing shall be no greater than two inches
across the smallest dimension.
(iii)
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:
(i)
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 Township pursuant to § 200-103C, a freestanding outlet structure may be exempted from this requirement;
(ii)
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 § 200-103F for an illustration of safety ledges in a stormwater management BMP; and
(iii)
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 (3:1).
D.
Embankments for stormwater management measures shall be designed
in accordance with the requirements of the Standards for Soil Erosion
and Sediment Control in New Jersey, January 2014, as amended, and
are to be constructed impermeable core of inorganic silts and clays
(Unified Soil Classification ML CL materials). Embankments shall be
provided with an emergency spillway designed to convey the facility's
maximum design storm plus 50%, with a minimum of one-foot of freeboard
to the proposed top of embankment elevation.
E.
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 Township that the variance or exemption
will not constitute a threat to public safety.
F.
Safety ledge illustration.
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Elevation View - Basin Safety Ledge Configuration
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A.
B.
Site development stormwater plan approval. The applicant's site development project shall be reviewed as a part of the review process by the Township board or official from which Township approval is sought. That Township board or official shall consult the Township's review engineer to determine if all of the checklist requirements have been satisfied and to further determine if the project meets the standards set forth in this Article XXI.
C.
Checklist for site development stormwater plan. The following information
shall be required:
(1)
Topographic base map. Topographic base map of the site shall 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 one-foot contour intervals and in the North American Vertical Datum of 1988 (NAVD 88). The map is to indicate the following, as appropriate: existing surface water drainage, riparian zones and steep slopes per § 200-149, soil types, perennial or intermittent streams, Greenbelt areas, limits and normal water surface elevation of existing water bodies, wetlands and flood plains along with their appropriate buffer strips, vegetative and other pervious surfaces, existing man-made structures, roads, bearing and distances of project property lines, existing easements or property reservations, and significant natural and manmade features not otherwise shown. The reviewing engineer may require additional upstream tributary drainage system information, as necessary.
(2)
Environmental site analysis. A written and graphic description of the natural and man-made features of the site and its surroundings is to be submitted. This description is to 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. Provision of an Environmental Impact Statement prepared in compliance with § 200-23, Environmental considerations, shall be deemed to satisfy this requirement.
(3)
Project description and site plans. Provide a map or maps at
the scale of the topographical base map indicating the existing and
proposed land use cover conditions, and including location of 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 soil test locations with seasonal high groundwater elevations
(observed or estimated). A written description of the site plan including
justifications for proposed changes in natural conditions shall also
be provided.
(4)
Land use planning and stormwater source control plan. This plan shall provide a demonstration of how the goals and standards of § 200-100.1 through § 200-101.2 are being met. The focus of this plan shall be to describe how the site is being developed to meet the objectives of maintaining groundwater recharge, addressing stormwater quality and mitigating stormwater quantity increases 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 provided:
(a)
Total area to be disturbed by the project; proposed surface
contours after construction; drainage area to each stormwater BMP
with breakdown of land area to be occupied by each stormwater BMP,
total area to be paved or otherwise built upon, and total area to
remain pervious; the location of each stormwater outfall and each
stormwater BMP in NAD 1983 State Plane New Jersey FIPS 2900 US Feet
and in the North American Vertical Datum of 1988 (NAVD 88), and written
summary tables indicating required and achieved groundwater recharge,
required and achieved stormwater quality control and required and
achieved stormwater quantity control achieved, listing values for
each BMP and for the project as a whole.
(b)
Details of all stormwater management facility designs, both
during and after construction, including precautions and protections
to be taken during construction, 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)
Provide comprehensive hydrologic and hydraulic design calculations for the pre-development and post-development conditions for the required design storms specified in § 200-101, prepared in accordance with the requirements of §§ 200-101.1 and 200-101.2 of this Article XXI by a qualified New Jersey licensed Professional Engineer.
(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 prepared by a qualified licensed professional 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. All soils investigation and testing shall be performed in accordance with soil testing criteria outlined in Chapter 12 of the NJ BMP Manual.
(7)
Maintenance and repair planning. A preliminary Maintenance Plan is to be provided meeting the requirements outlined in § 200-105. The planning and design of stormwater management facilities shall take into consideration aspects of future maintenance requirements, including ease of access, and the costs of maintenance and repair and replacement of their components.
(8)
A major development stormwater summary form. Submit a preliminary
version of the NJDEP's Tier A MS4 NJPDES Permit Attachment D
- Major Development Stormwater Summary form for the major development.
D.
Waiver from submission requirements. The Township official or board reviewing an application under this Article XXI may, in consultation with the Township's review engineer, waive submission of any of the requirements in § 200-104C(1) through (6) of this Article XXI 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.
B.
Maintenance Plan and Maintenance Responsibilities.
(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. The Plan shall contain information
on BMP location, design, ownership, maintenance tasks and frequencies,
and other details as specified in Chapter 8 of the NJ BMP Manual,
as well as the tasks specific to the type of BMP, as described in
the applicable chapter containing design specifics.
(3)
If the Maintenance Plan identifies a person other than the property
owner (for example, a developer, a public agency or homeowners'
association) as having the responsibility for maintenance, the Plan
shall include documentation of such person's or entity's
agreement to assume this responsibility, or of the owner's obligation
to dedicate a stormwater management facility to such person under
an applicable ordinance or regulation.
(4)
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. An individual property
owner within a development may be assigned incidental tasks, such
as weeding of a green infrastructure BMP, provided the individual
agrees to assume these tasks; however, the individual cannot be made
legally responsible for all of the maintenance required.
(5)
If the party responsible for maintenance identified under § 200-105B(3) above is not a public agency, the approved Maintenance Plan, and any future revisions based on § 200-105B(7) below, shall be documented by Deed Notice recorded upon the deed of record for each property on which the maintenance described in the Maintenance Plan must be undertaken as outlined in § 200-101M.
(6)
Preventative and corrective maintenance shall be performed to
maintain the functional parameters (storage volume, infiltration rates,
inflow/outflow capacity, etc.) of the stormwater management measure,
including, but not limited to, 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 non-vegetated linings.
(7)
The party responsible for maintenance identified under § 200-105B(3) above shall perform all of the following requirements:
(a)
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;
(b)
Evaluate the effectiveness of the maintenance plan at least
once per year and adjust the plan and deed as needed; and
(c)
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 § 200-105B(6) and (7) above.
(8)
The party responsible for maintenance identified under § 200-105B(3) above shall submit a copy of the detailed log along with an annual inspection report prepared by a Professional Engineer licensed in New Jersey or a New Jersey certified stormwater inspector to the Township of West Windsor Department of Community Development, Division of Engineering, by June 30th of each year. The inspection report and log shall include those items outlined within the Maintenance Plan, and not be limited to condition assessment with recommendations on the following items:
(a)
Stormwater BMP outlet structure and outfall, including escape
provisions as outlined in N.J.A.C. 7:8-6.2;
(b)
Vegetation cover and health;
(c)
Trash racks and overflow grates;
(d)
Embankments;
(e)
Erosion, including outfall;
(f)
Sediment and debris removal;
(g)
Retention pond maintenance; and
(h)
An evaluation of the effectiveness of the current Maintenance
Plan and any recommended adjustments to the plan.
(9)
The party responsible for maintenance 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 § 200-105B(7) and (8).
(10)
Penalty for failure to provide annual inspection report and maintenance log: $100. Each act or violation, and every day upon which any violation shall occur or continues to occur, shall constitute a separate offense as provided for in Chapter 1, General Provisions, Article II, § 1-3, General penalty, of the Township Code.
(11)
The requirements of § 200-105B(3), (4) and (8) do not apply to stormwater management facilities that are dedicated to and accepted by the Township or another governmental agency, subject to all applicable Township stormwater general permit conditions, as issued by the Department.
(12)
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 Township shall so notify the responsible
party in writing. Upon receipt of that notice, the responsible party
shall have 14 calendar days to effect maintenance and repair of the
facility in a manner that is approved by the Township Engineer or
his designee. The Township, in its discretion, may extend the time
allowed for effecting maintenance and repair for good cause. If the
responsible party fails or refuses to perform such maintenance and
repair, the Township or County may immediately proceed to do so and
shall bill the cost thereof to the responsible party. Nonpayment of
such bill may result in a lien on the property.
C.
Nothing in this subsection shall preclude the Township from requiring
the posting of a performance or maintenance guarantee in accordance
with N.J.S.A. 40:55D-53.
Such stormwater control improvements on the site, during and upon completion of their construction, shall be subject to inspection and approval by the Township Engineer, following the provisions of § 200-92 Inspection and fees. No underground installation shall be covered until inspected and approved. Approval or reasons for withholding approval shall be given promptly, and in any event within three business days following an inspection. If work proceeds without such approval or is not in compliance therewith, the Township Engineer, in addition to any other remedies available to the Township, may issue an order requiring immediate cessation of the affected work and prohibiting resumption thereof (a "stop-work order") until approval is obtained or noncompliance is corrected.
A.
Prior to the acceptance by the Township of any constructed stormwater
BMPs, the developer shall provide a survey prepared by a land surveyor
licensed in New Jersey showing the location and pertinent details
of all stormwater BMPs and stormwater outfalls as built. The survey
shall identify the location of the stormwater management measure(s)
and all stormwater outfalls in NAD 1983 State Plane New Jersey FIPS
2900 US Feet and in the North American Vertical Datum of 1988 (NAVD
88). Submission shall be in the form of both signed and sealed prints
AND digital data file for incorporation of the information into the
Township's GIS database, as directed by the Township Engineer.
Alternate standards may be permitted subject to the prior review and
approval of the Township Engineer.
B.
The developer's engineer shall perform an inspection of the
project, review the as-built survey and certify to the Township, in
writing, that said facilities were constructed in accordance with
the approved stormwater control plans. Along with the certification
the developer shall provide a final completed version of the NJDEP's
Major Development Stormwater Summary form for the project.
A.
Stormwater control improvements shall be completely installed and
stabilized, except for final landscaping, prior to issuance of any
building permit for the development or prior to any increase in impervious
cover above the existing amount of impervious cover prior to the approved
project.
B.
Final landscaping shall be completed in accordance with the schedule
established for the completion of all other improvements, and the
appropriate planting seasons.
Any person who erects, constructs, alters, repairs, converts, maintains or uses any building, structure or land in violation of this article where no specific penalty is provided regarding the section violated shall be subject to the penalties as provided in Chapter 1, General Provisions, Article II, § 1-3, General penalty, of the Township Code.
Each section, subsection, sentence, clause and phrase of this
article is declared to be an independent section, subsection, sentence,
clause and phrase, and the finding or holding of any such portion
of this article to be unconstitutional, void, or ineffective for any
cause, or reason, shall not affect any other portion of this article.
