This chapter shall be known and may be cited as the "Stormwater
Management Ordinance."
A.
Policy statement.
(1)
Reduce flood damage, including damage to life and property;
(2)
Minimize, to the extent practical, any increase in stormwater runoff
from any new development;
(3)
Reduce soil erosion from any development or construction project;
(4)
Assure the adequacy of existing and proposed culverts and bridges,
and other in-stream structures;
(5)
Maintain groundwater recharge;
(6)
Prevent, to the greatest extent feasible, an increase in nonpoint
pollution;
(7)
Maintain the integrity of stream channels for their biological functions,
as well as for drainage;
(8)
Minimize pollutants in stormwater runoff from new and existing development
in order to restore, enhance and maintain the chemical, physical,
and biological integrity of the waters of the state, to protect public
health, to safeguard fish and aquatic life and scenic and ecological
values, and to enhance the domestic, municipal, recreational, industrial
and other uses of water;
(9)
Protect public safety through the proper design and operation of
stormwater management basins; and
(10)
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.
B.
Purpose.
(1)
It is hereby determined that the lakes and waterways within the City
of Linwood of Atlantic County may be subject to flooding; that development
tends to accentuate the possibility of such flooding by increasing
stormwater runoff, due to alterations of the hydrologic response of
the watershed in changing from the undeveloped to the developed condition;
that such increased stormwater runoff produced by development of real
property contributes to the possibility of increased quantities of
waterborne pollutants and tends to increase channel erosion; that
such increased stormwater runoff, increased erosion potential and
increased pollution potential constitutes the possibility of the deterioration
of the water resources of the City of Linwood, the County of Atlantic
and the State of New Jersey; and that such impacts can be controlled
to some extent by the regulation of stormwater runoff from such development.
It is determined that it is in the public interest to regulate the
development of real property and to establish standards to regulate
the additional discharge of stormwater runoff from such developments
as provided in this chapter.
(2)
It is the purpose of this chapter to be consistent with established
minimum stormwater management requirements and controls for major
development, in accordance with N.J.A.C. 5:21, New Jersey Residential
Site Improvement Standards, and N.J.A.C. 7:8, Stormwater Management
Rules.
(3)
In addition, this chapter seeks to expand those same minimum stormwater
management requirements for certain developments not defined as "major
development."
C.
Applicability.
(1)
For "major development," N.J.A.C. 5:21, New Jersey Residential Site
Improvement Standards, N.J.A.C. 7:8, Stormwater Management Rules,
and the requirements of this chapter shall apply.
(3)
All other nonmajor development shall comply with this chapter (excluding § 238-5), except that a stormwater management plan shall not be required. The lack of a stormwater management plan in these instances shall not relieve any property owner, developer, building contractor, etc., from the requirements of this chapter.
(4)
This chapter shall also be applicable to all major developments undertaken
by the City of Linwood.
(5)
The applicant may request a waiver from the strict compliance with
the standards if it can be demonstrated and documented that the enforcement
of one or more of these standards will cause an undue hardship.
(6)
These standards shall apply unless more strict controls have been
established by other agencies having jurisdiction. In those areas,
the strictest standard shall control.
D.
Procedure.
(1)
Burden of proof. Whenever an applicant seeks a City approval of a
development to which this chapter is applicable from any board or
official of the City, that applicant shall be required to demonstrate
that the project meets the standards set forth in this chapter, including
a stormwater management plan.
(2)
Submission materials due. The applicant shall submit materials, as
required by this chapter hereof, to the City board or official from
which the applicant seeks City approval prior to or at the same time
of submission of an application for City approval.
(3)
Review. The applicant's project shall be reviewed by the City board
or official from which the applicant seeks City approval. That City
board or official shall consult with the City Engineer to determine
if the project meets the standards set forth in this chapter. A $500
escrow fee will be assessed for the City's review of the stormwater
management plan.
(4)
Time for decision. The City board or official shall promptly determine
if the project meets the standards set forth in this chapter. The
time for that determination should be the time permitted to review
and act on the applicant's application for a City approval.
(5)
Failure to comply. Failure of the applicant to demonstrate that the
project meets the standards set forth in this chapter is reason to
deny the applicant's underlying application for a City approval.
(6)
Variance. For good reason, the City may grant a waiver of the standards
given in this chapter.
E.
Goals and objectives. In order to protect, maintain and enhance both
the immediate and long-term health and general welfare of its citizens,
Linwood established the following goals and objectives for stormwater
control:
(1)
To ensure that stormwater runoff after development of a site will
approximate the same rate of flow and timing of stormwater runoff
that would have occurred under predevelopment conditions.
(2)
To maintain the adequacy of existing and proposed culverts and bridges,
dams and other conveyance structures.
(3)
To minimize erosion and sedimentation from any development or construction
project.
(4)
To the maximum extent practicable, alleviate any deleterious drainage
condition(s) on or adjacent to any site proposed for development.
F.
Compatibility with other permit and ordinance requirements. Development
approvals issued for subdivisions and site plans pursuant to this
chapter 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 chapter shall be held to be the minimum requirements for the
promotion of the public health, safety, and general welfare. This
chapter is not intended to interfere with, abrogate, or annul any
other ordinance, rule or regulation, statute, or other provision of
law except that, where any provision of this chapter 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.
Unless specifically defined below, words or phrases used in
this chapter shall be interpreted so as to give them the meaning they
have in common usage and to give this chapter 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.
Best management practice as defined in the New Jersey Stormwater
Best Management Practices Manual.
Those areas within boundaries accepted by the Department
pursuant to N.J.A.C. 7:7-13.16.
The geographic depiction of the boundaries for coastal planning
areas, CAFRA centers, CAFRA cores and CAFRA nodes pursuant to N.J.A.C.
7:7-13.16.
The City of Linwood.
An infiltration system, sand filter designed to infiltrate,
standard constructed wetland, or wet pond, established in accordance
with N.J.A.C. 7:8-4.2(c)14, that is designed and constructed in accordance
with the New Jersey Stormwater Best Management Practices Manual, or
an alternate design, approved in accordance with N.J.A.C. 7:8-5.2(g),
for an infiltration system, sand filter designed to infiltrate, standard
constructed wetland, or wet pond and that complies with the requirements
of this chapter.
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 City, generally including housing and access to public
transportation.
The County of Atlantic.
An agency designated by the County Board of Chosen Freeholders
to review the City's stormwater management plans and implementing
ordinance(s). The county review agency is the Atlantic County Department
of Regional Planning and Development.
The New Jersey Department of Environmental Protection.
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.
A state development and redevelopment plan center as designated
by the State Planning Commission, such as urban, regional, town, village,
or hamlet.
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 City review of
any activity not exempted by the Right to Farm Act, N.J.S.A. 4:1C-1
et seq.
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 water body or
to a particular point along a receiving water body.
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; habitat of endangered or threatened species; large
areas of contiguous open space or upland forest; steep slopes; and
wellhead 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.
Pursuant to N.J.A.C. 7:8-1.2, "impervious surface" means
a surface that has been covered with a layer of material so that it
is highly resistant to infiltration by water.
The process by which water seeps into the soil from precipitation.
An individual "development," as well as multiple developments
that individually or collectively result in:
"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 meet any one or more of Subsection A(1), (2), (3), or (4) above. 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.
A development project that results in the issuance of a new
certificate of occupancy before the area can be occupied.
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 chapter. 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 chapter. Alternative stormwater management measures, removal rates, or calculation methods may be utilized, subject to any limitations specified in this chapter, provided the design engineer demonstrates to the municipality, in accordance with § 238-5H(2)(a) of this chapter and N.J.A.C. 7:8-5.2(g), that the proposed measure and its design will contribute to achievement of the design and performance standards established by this chapter.
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.
Any individual, corporation, company, partnership, firm,
association, the City of Linwood or political subdivision of this
state subject to City jurisdiction pursuant to the Municipal Land
Use Law, N.J.S.A. 40:55D-1 et seq.
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, City,
agricultural, and construction waste or runoff, or other residue discharged
directly or indirectly to the land, groundwaters or surface waters
of the state, or to a domestic treatment works. "Pollutant" includes
both hazardous and nonhazardous pollutants.
The amount of water from precipitation that infiltrates into
the ground and is not evapotranspired.
Any of the following, alone or in combination:
A net increase of impervious surface;
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);
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
water;
A net increase in motor vehicle surface; and/or 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.
The lot or lots upon which a development is to occur or has
occurred.
All unconsolidated mineral and organic material of any origin.
Pursuant to 7:8-5.5(h), 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.
Areas shall be established for the protection of water quality, aesthetic
value, exceptional ecological significance, exceptional recreational
significance, and exceptional fisheries significance of those established
Category One waters.
The State of New Jersey.
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.
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 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).
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
nonstormwater 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.
A flood hazard area in which the flood elevation resulting
from the two-, ten-, or 100-year storm, as applicable, is governed
by tidal flooding from the Atlantic Ocean. Flooding in a tidal flood
hazard area may be contributed to, or influenced by, stormwater runoff
from inland areas, but the depth of flooding generated by the tidal
rise and fall of the Atlantic Ocean is greater than flooding from
any fluvial sources. In some situations, depending upon the extent
of the storm surge from a particular storm event, a flood hazard area
may be tidal in the 100-year storm, but fluvial in more frequent storm
events.
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 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, ford (if
above grade), retaining wall, and weir.
The ocean and its estuaries, all springs, streams, wetlands,
and bodies of surface water or groundwater, whether natural or artificial,
within the boundaries of the State of New Jersey or subject to its
jurisdiction.
Pursuant to N.J.A.C. 7:8-1.2, "wetlands" or "wetland" means
an area that is inundated or saturated by surface water or groundwater
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.
Design and performance standards for stormwater management measures.
(1)
Stormwater management measures shall be developed to meet the erosion control, groundwater recharge, stormwater runoff quantity, and stormwater runoff quality standards stated in this section as well as those standards for stormwater management stated in § 238-5. 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 stated in § 238-5 apply 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 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.
(3)
For site improvements regulated under the Residential Site Improvement
Standards (RSIS) at N.J.A.C. 5:21, the RSIS shall apply in addition
to this section except to the extent the RSIS are superseded by this
section or alternative standards applicable under a regional stormwater
management plan or water quality management plan adopted in accordance
with Department rules.
(4)
All developments shall demonstrate through hydrologic and hydraulic
analysis that quantity and quality standards are met as follows.
(a)
The total volume of runoff leaving the site from the postdevelopment
condition shall not be greater than the total volume of runoff leaving
the site from the predevelopment condition, nor shall there be any
alterations of the flow pattern of stormwater runoff from the lot
such that flooding, erosion, sedimentation, loss of water supply or
other harmful effect will occur.
(b)
The volume of runoff resulting from the water quality design
storm defined as 1.25 inches in a two-hour period or the one-year,
twenty-four-hour, Type III design storm shall be completely retained
and infiltrated on site.
(5)
Wetlands.
(a)
No land development shall be carried out within 50 feet of a
wetland or in an area adjacent to a wetland area where the seasonal
high-water table is three feet or less, unless the applicant can demonstrate
that the proposed development will not result in significant adverse
impact on any drainage structure.
(b)
A significant adverse impact shall be deemed to exist if:
(6)
Methods of management.
(a)
The following is a list of various control methods which may
be utilized in stormwater management systems, if appropriate. The
choice of control techniques is not limited to the ones appearing
on this list. However, it will be the policy of the City to encourage
the use of retention basins wherever possible.
(b)
The use of other control methods which meet the criteria in
this section will be permitted when approved by the Engineer. Various
combinations of methods should be tailored to suit the particular
requirements of the type of development and the topographic features
of the project area.
(7)
Drainage easements.
(a)
All stormwater management plans shall illustrate the pathway
of positive outflow to the nearest stormwater easement, stream, lake,
pond or other natural watercourse. Prior to receiving the final approval,
the applicant shall obtain the necessary easements corresponding with
the flow patterns illustrated on the plans should those patterns affect
the present or future use of adjoining parcels by increasing the quantity
of runoff over the adjoining parcel.
(b)
Where a subdivision is traversed by a watercourse, surface or underground drainageway or drainage system, channel or stream, there shall be provided and dedicated a drainage right-of-way easement to the City conforming substantially to the lines of such watercourse, and such further width or construction, or both, as will be adequate to accommodate expected stormwater runoff meeting any minimum widths and locations shown on any adopted Official Map and/or Master Plan and, as a minimum, that fixed in § 238-3 defined as "stream corridor." Such easement dedication shall be expressed on the plan as follows: "Drainage and utility right-of-way easement granted to the City of Linwood."
(8)
Drainage structures in county or state right-of-way. Drainage structures
which are located within New Jersey or Atlantic County highway rights-of-way
shall be approved by the state or county agency, and a letter from
that office indicating such approval shall be directed to the administrator
of the Planning Board and shall be received prior to the final plat
approval. Drainage structures abutting a brook or stream whose drainage
area, up to and including the subdivision or development, is greater
than 50 acres or within a 100-year floodplain shall be required to
secure a stream encroachment permit from the New Jersey Department
of Environmental Protection, Division of Water Resources, in accordance
with the latest criteria, prior to authorization of final approval.
A copy of said permit shall be forwarded to the Administrator of the
Planning Board and attached to the final engineering plans.
A.
The development shall incorporate a maintenance plan for the stormwater management measures incorporated into the design of a development in accordance with § 238-14.
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 13:1B-15.150, particularly
Helonias bullata (swamp pink) and/or Clemmys muhlenbergii (bog turtle).
C.
The following linear development projects are exempt from the groundwater recharge, stormwater runoff quantity, and stormwater runoff quality requirements of § 238-5G:
(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 quantity, and stormwater runoff quality requirements of § 238-5G 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 alternative analysis that, through the use of nonstructural and structural stormwater management strategies and measures, the alternative selected complies with the requirements of § 238-5G to the maximum extent practicable;
(3)
The applicant demonstrates that, in order to meet the requirements of § 238-5G, 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 Subsection D(3) above within the upstream drainage area of the receiving stream that would provide additional opportunities to mitigate the requirements of § 238-5G that were not achievable on site.
E.
Nonstructural stormwater management strategies.
(1)
To the maximum extent practicable, the standards in § 238-5G shall be met by incorporating nonstructural stormwater management strategies set forth at § 238-7 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 Subsection E(2) below into the design of a particular project, the applicant shall identify the strategy considered and provide a basis for the contention.
(2)
If the applicant contends that it is not practical for engineering, environmental or safety reasons to incorporate any of the nine nonstructural strategies into the design of a particular project, the applicant shall provide a detailed rationale establishing a basis for the contention that use of the strategy is not practical on the site. This rationale shall be submitted, in accordance with the checklist requirements established by § 238-13, to the City. A determination by the City that this rationale is inadequate or without merit shall result in a denial of the application unless one of the following conditions is met:
(a)
The land use planning and source control plan is amended to
include a description of how all nine nonstructural measures will
be implemented on the development site, and the amended plan is approved
by the City;
(c)
The land use planning and source control plan is amended to
provide an adequate rationale for the contention that use of the particular
strategy is not practical on the site, and the amended plan is approved
by the City.
(3)
In addition to all other requirements of this section, each applicant
shall demonstrate that, at a minimum, existing trees and vegetation
on the development site will be preserved, protected and maintained
according to the minimum standards established by provisions of the
City Land Use Ordinance, Zoning Ordinance or by conditions of zoning
or variance approval. Existing trees and vegetation shall be protected
during construction activities in accordance with the standard for
tree protection during construction provided in the New Jersey State
Soil Conservation Committee Standards for Soil Erosion and Sediment
Control in New Jersey, which is incorporated herein by reference,
as amended and supplemented.
(4)
Any land area used as a nonstructural stormwater management measure to meet the performance standards in §§ 238-5 and 238-6 shall be dedicated to a government entity; shall be subjected to a conservation easement filed with the appropriate County Clerk's office; or shall be subjected to an equivalent form of restriction approved by the City that ensures that that measure, or equivalent stormwater management measure, is maintained in perpetuity, as detailed in § 238-14 of this chapter.
(5)
Guidance for nonstructural stormwater management strategies is available
in the New Jersey BMP Manual, which may be obtained from the NJDEP's
website at www.njstormwater.org.
F.
Threatened and endangered species and associated habitat standards.
(1)
Stormwater management measures shall avoid adverse impacts of the
development on habitat for threatened and endangered species, in accordance
with N.J.A.C. 7:8-5.2(c).
G.
Erosion control, groundwater recharge and runoff quantity and quality
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 at N.J.A.C.
2:90.
(2)
The minimum design and performance standards for groundwater recharge
are as follows:
(a)
The design engineer shall, using the assumptions and factors for stormwater runoff and groundwater recharge calculations at § 238-6, either:
[1]
Demonstrate through hydrologic and hydraulic analysis that the
site and its stormwater management measures maintain 100% of the average
annual preconstruction groundwater recharge volume for the site; or
[2]
Demonstrate through hydrologic and hydraulic analysis that the
increase of stormwater runoff volume from preconstruction to postconstruction
for the two-year storm is infiltrated.
(b)
The following types of stormwater shall not be recharged:
[1]
Stormwater from areas of high pollutant loading. High pollutant
loading areas are areas in industrial and commercial developments
where solvents and/or petroleum products are loaded/unloaded, stored,
or applied; areas where pesticides are loaded/unloaded or stored;
areas where hazardous materials are expected to be present in greater
than "reportable quantities" as defined by the United States Environmental
Protection Agency (EPA) at 40 CFR 302.4; areas where recharge would
be inconsistent with a Department-approved remedial action work plan
or landfill closure plan and areas with high risks for spills of toxic
materials, such as gas stations and vehicle maintenance facilities;
and
[2]
Industrial stormwater exposed to source material. "Source material"
means any material(s) or machinery, located at an industrial facility,
which 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.
(c)
The design engineer shall assess the hydraulic impact on the
groundwater table and design the site so as to avoid adverse hydraulic
impacts. Potential adverse hydraulic impacts include, but are not
limited to, exacerbating a naturally or seasonally high-water table
so as to cause surficial ponding, flooding of basements, or interference
with the proper operation of subsurface sewage disposal systems and
other subsurface structures in the vicinity or downgradient of the
groundwater recharge area.
(3)
The minimum design and performance standards for stormwater runoff quantity are as follows. In order to control stormwater runoff quantity impacts, the design engineer shall, using the assumptions and factors for stormwater runoff calculations at § 238-6, complete one of the following:
(a)
Demonstrate through hydrologic and hydraulic analysis that for
stormwater leaving the site, postconstruction runoff hydrographs for
the two-, ten- and 100-year storm events do not exceed, at any point
in time, the preconstruction runoff hydrographs for the same storm
events;
(b)
Demonstrate through hydrologic and hydraulic analysis that there
is no increase, as compared to the preconstruction condition, in the
peak runoff rates of stormwater leaving the site for the two-, ten-
and 100-year storm events and that the increased volume or change
in timing of stormwater runoff will not increase flood damage at or
downstream of the site. This analysis shall include the analysis of
impacts of existing land uses and projected land uses assuming full
development under existing zoning and land use ordinances in the drainage
area;
(c)
Design stormwater management measures so that the postconstruction
peak runoff rates for the two-, ten- and 100-year storm events are
50%, 75% and 80%, respectively, of the preconstruction peak runoff
rates. The percentages apply only to the postconstruction stormwater
runoff that is attributable to the portion of the site on which the
proposed development or project is to be constructed; or
(d)
In tidal flood hazard areas, stormwater runoff quantity analysis in accordance with Subsections G(3)(a), (b) and (c) above is required unless the design engineer demonstrates through hydrologic and hydraulic analysis that the increased volume, change in timing, or increased rate of the stormwater runoff, or any combination of the three, will not result in additional flood damage below the point of discharge of the major development. No analysis is required if the stormwater is discharged directly into any ocean, bay, inlet, or the reach of any watercourse between its confluence with an ocean, bay, or inlet and downstream of the first water control structure.
(4)
The minimum design and performance standards for stormwater quality
are as follows:
(a)
Stormwater management measures shall be designed to reduce the
postconstruction load of total suspended solids (TSS) in stormwater
runoff by 80% of the anticipated load, expressed as an annual average,
which shall be achieved for the stormwater runoff from the net increase
of motor vehicle surface. 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 an 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. The calculation of the volume of runoff may take into
account the implementation of nonstructural and structural stormwater
management measures.
(b)
For purposes of TSS reduction calculations, see § 238-6 for 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 § 238-11, or found on the Department's website at www.njstormwater.org. The BMP Manual and other sources of technical guidance are listed in § 238-11. 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, PO Box 418, Trenton, New Jersey, 08625-0418.
(c)
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 — (AxB)/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
|
(d)
If there is more than one on-site drainage area, the 80% 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.
(e)
Stormwater management measures shall also be designed to reduce, to the maximum extent feasible, the postconstruction 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 § 238-5G.
(f)
In accordance with the definition of "FW1" at N.J.A.C. 7:9B-1.4,
stormwater management measures shall be designed to prevent any increase
in stormwater runoff to waters classified as FW1.
(g)
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:
[1]
The applicant shall preserve and maintain a special water resource
protection area in accordance with one of the following:
[a]
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 center
line of the waterway where the bank is not defined, consisting of
existing vegetation or vegetation allowed to follow natural succession.
[b]
Encroachment within the designated special water
resource protection area under Subsection G(4)(g)[1][a] 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 center line of the waterway
where the bank is undefined. All encroachments proposed under this
subsection shall be subject to review and approval by the Department.
[2]
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.
[3]
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:
[a]
Stabilization measures shall not be placed within
150 feet of the Category One waterway;
[b]
Stormwater associated with discharges allowed by
this section shall achieve a 95% TSS postconstruction removal rate;
[c]
Temperature shall be addressed to ensure no impact
on the receiving waterway;
[d]
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;
[e]
A conceptual project design meeting shall be held
with the appropriate Department staff and Soil Conservation District
staff to identify necessary stabilization measures; and
[f]
All encroachments proposed under this section shall
be subject to review and approval by the Department.
[4]
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 the City through provisions in the
adopted municipal stormwater management plan. If a stream corridor
protection plan for a waterway 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
shall maintain or enhance the current functional value and overall
condition of the special water resource protection area. 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.
(h)
The stormwater runoff quality standards do not apply to the
construction of one individual single-family dwelling, provided that
it is not part of a larger development or subdivision that has received
preliminary or final site plan approval prior to December 3, 2018,
and that the motor vehicle surfaces are made of permeable material(s)
such as gravel, dirt, and/or shells.
H.
Green infrastructure requirements.
(1)
When designed in accordance with the most current version of the
New Jersey Stormwater Best Management Practices Manual, the stormwater
management measures found at N.J.A.C. 7:8-5.2(f), Tables 5-1, 5-2
and 5-3, and listed below in Tables 1, 2 and 3 are presumed to be
capable of providing stormwater controls for the design and performance
standards as outlined in the tables below. Upon amendments of the
New Jersey Stormwater Best Management Practices to reflect additions
or deletions of BMPs meeting these standards, or changes in the presumed
performance of BMPs designed in accordance with the New Jersey Stormwater
BMP Manual, the Department shall publish in the New Jersey Registers
a notice of administrative change revising the applicable table. The
most current version of the BMP Manual can be found on the Department's
website at: http://njstormwater.org/bmp_manual2.htm.
(2)
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 rate or method to the municipality. A copy of any approved alternative stormwater management measure, alternative removal rate, and/or alternative method to calculate the removal rate shall be provided to the Department. Alternative stormwater management measures may be used to satisfy the requirements only if the measures meet the definition of green infrastructure. Alternative stormwater management measures that function in a similar manner to a BMP are subject to the contributory drainage area less than or equal to 2.5 acres, except for alternative stormwater management measures that function similarly to cisterns, grass swales, green roofs, standard constructed wetlands, vegetative filter strips, and wet ponds, which are not subject to a contributory drainage area limitation. Alternative measures that function similarly to standard constructed wetlands or wet ponds shall not be used for compliance with the stormwater runoff quality standard unless a variance in accordance with N.J.A.C. 7:8-4.6 or a waiver from strict compliance in accordance with § 238-5D.
(a)
Where the BMP tables in the NJ Stormwater Management Rules are
different due to updates or amendments with the tables in this chapter,
the BMP tables in the Stormwater Management Rules at N.J.A.C. 7:8-5.2(f)
shall take precedence.
|
Table 1
| ||||
|---|---|---|---|---|
|
Green Infrastructure BMPs for Groundwater Recharge, Stormwater
Runoff Quality, and/or Stormwater Runoff Quantity
| ||||
|
Best Management Practice
|
Stormwater Runoff Quality TSS Removal Rate
(percent)
|
Stormwater Runoff Quantity
|
Groundwater Recharge
|
Minimum Separation from Seasonal High Water Table
(feet)
|
|
Cistern
|
0
|
Yes
|
No
|
—
|
|
Dry well(a)
|
0
|
No
|
Yes
|
2
|
|
Grass swale
|
50 or less
|
No
|
No
|
2(e)
1(f)
|
|
Green roof
|
0
|
Yes
|
No
|
—
|
|
Manufactured treatment device(a)(g)
|
50 or 80
|
No
|
No
|
Dependent upon the device
|
|
Pervious paving system(a)
|
80
|
Yes
|
Yes(b)
No(c)
|
2(b)
1(c)
|
|
Small-scale bioretention basin(a)
|
80 or 90
|
Yes
|
Yes(b)
No(c)
|
2(b)
1(c)
|
|
Small-scale infiltration basin(a)
|
80
|
Yes
|
Yes
|
2
|
|
Small-scale sand filter
|
80
|
Yes
|
Yes
|
2
|
|
Vegetative filter strip
|
60-80
|
No
|
No
|
—
|
|
(Notes corresponding to annotations (a) through (g) are found at the end of Table
3)
|
|
Table 2
| ||||
|---|---|---|---|---|
|
Green Infrastructure BMPs for Stormwater Runoff Quantity
(or for Groundwater Recharge and/or Stormwater Runoff Quality
with a Waiver or Variance from N.J.A.C. 7:8-5.3)
| ||||
|
Best Management Practice
|
Stormwater Runoff Quality TSS Removal Rate
(percent)
|
Stormwater Runoff Quantity
|
Groundwater Recharge
|
Minimum Separation from Seasonal High-Water Table
(feet)
|
|
Bioretention system
|
80 or 90
|
Yes
|
Yes(b)
No(c)
|
2(b)
1(c)
|
|
Infiltration basin
|
80
|
Yes
|
Yes
|
2
|
|
Sand filter(b)
|
80
|
Yes
|
Yes
|
2
|
|
Standard constructed wetland
|
90
|
Yes
|
No
|
N/A
|
|
Wet pond(d)
|
50-90
|
Yes
|
No
|
N/A
|
|
(Notes corresponding to annotations (b)through(d) are found at the end of Table
3)
|
|
Table 3
| ||||
|---|---|---|---|---|
|
BMPs for Groundwater Recharge, Stormwater Runoff Quality, and/or
Stormwater Runoff Quantity
only with a Waiver or Variance from N.J.A.C. 7:8-5.3
| ||||
|
Best Management Practice
|
Stormwater Runoff Quality TSS Removal Rate
(percent)
|
Stormwater Runoff Quantity
|
Groundwater Recharge
|
Minimum Separation from Seasonal High-Water Table
(feet)
|
|
Blue roof
|
0
|
Yes
|
No
|
N/A
|
|
Extended detention basin
|
40-60
|
Yes
|
No
|
1
|
|
Manufactured treatment device(h)
|
50 or 80
|
No
|
No
|
Dependent upon the device
|
|
Sand filter(c)
|
80
|
Yes
|
No
|
1
|
|
Subsurface gravel wetland
|
90
|
No
|
No
|
1
|
|
Wet pond
|
50-90
|
Yes
|
No
|
N/A
|
|
Notes to Tables 1, 2, and 3:
| |
|---|---|
|
(a)
|
Subject to the applicable contributory drainage area limitation specified at § 238-5I(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 § 238-3;
|
|
(h)
|
Manufactured treatment devices that do not meet the definition of "green infrastructure" at § 238-3.
|
I.
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 § 238-5G(2) and § 238-5G(4), the design engineer shall utilize green infrastructure BMPs identified in Table 1 at § 238-5H(2)(a) and/or an alternative stormwater management measure approved in accordance with § 238-5H(2). 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 § 238-5D 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 § 238-5H(2) may be used to meet the groundwater recharge, stormwater runoff quality, and stormwater runoff quantity standards at § 238-5G(2), (3) and (4).
(5)
For separate or combined storm sewer improvement projects, such as sewer separation, undertaken by a government agency or public utility (for example, a sewerage company), the requirements of this subsection shall only apply to areas owned in fee simple by the government agency or utility, and areas within a right-of-way or easement held or controlled by the government agency or utility; the entity shall not be required to obtain additional property or property rights to fully satisfy the requirements of this subsection. Regardless of the amount of area of a separate or combined storm sewer improvement project subject to the green infrastructure requirements of this subsection, each project shall fully comply with the applicable groundwater recharge, stormwater runoff quality control, and stormwater runoff quantity standards at § 238-5G(2), (3) and (4), unless the project is granted a waiver from strict compliance in accordance with § 238-5D.
A.
Methods of calculating stormwater runoff quantity:
(1)
The design engineer shall calculate runoff using one of the following
methods:
(a)
The USDA Natural Resources Conservation Service (NRCS) methodology, including the NRCS Runoff Equation and Dimensionless Unit Hydrograph, as described in Chapters 7, 9, 10, 15 and 16 Part 630, Hydrology National Engineering Handbook, incorporated herein by reference as amended and supplemented. This methodology is additionally described in Technical Release 55 - Urban Hydrology for Small Watersheds (TR-55), dated June 1986, incorporated herein by reference as amended and supplemented. Information regarding the methodology is available from the Natural Resources Conservation Service website at: http://www.nrcs.usda.gov/Internet/FSE DOCUMENTS/stelprdb1044171.pdf or at United States Department of Agriculture Natural Resources Conservation Service, 220 Davison Avenue, Somerset, New Jersey 08873; or
(b)
The Rational Method for peak flow and the Modified Rational
Method for hydrograph computations. The Rational and Modified Rational
Methods are described in "Appendix A-9 Modified Rational Method" in
the Standards for Soil Erosion aned Sediment Control in New Jersey,
January 2014. This document is available from the State Soil Conservation
Committee or any of the Soil Conservation Districts listed at N.J.A.C.
2:90-1.3(a)3. The location, address, and telephone number for each
Soil Conservation District is available from the State Soil Conservation
Committee, PO Box 330, Trenton, New Jersey 08625. This document is
also available at: http://www.nj.gov/agriculture/divisions/anr/pdf/2014NJSoilErosionControlStandardsComplete.pdf.
(2)
For the purpose of calculating runoff coefficients and groundwater recharge, there is a presumption that the preconstruction 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 § 238-6A(1)(a) and the Rational and Modified Rational Methods at § 238-6A(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 preconstruction 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
preconstruction 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.
(6)
Detention facilities. For the purpose of determining the total quantity
of runoff prior to and following development, the Soil Conservation
Service's Technical Release No. 55 shall be used. This methodology
shall serve as the basis for determining total storage capacity required
subject to the guidelines identified in previous sections of this
report and will also serve as the basis for determining release rates
from the one-year, two-year, ten-year and fifty-year storms.
(7)
Calculations shall be computed on the basis of all areas upstream
of the parcel(s) in question. Peak rates of runoff shall be computed
for the entire area and design release rates computed on the basis
of preexisting conditions for the entire watershed.
(8)
The maximum curve number values suitable for use in computing runoff
values for on-site developed conditions are as follows:
|
Hydrologic Soil Group
|
Curve Number
|
|---|---|
|
A
|
25
|
|
B
|
55
|
|
C
|
70
|
|
D
|
77
|
(9)
Rainfall values for each of the storms used in designing stormwater
facilities include (Type III rainfall distribution):
|
Storm Event
|
Total Rainfall
(inches)
|
|---|---|
|
1-year
|
2.8
|
|
2-year
|
3.3
|
|
10-year
|
5.2
|
|
50-year
|
7.6
|
|
100-year
|
8.9
|
(10)
The applicant must identify:
(a)
The peak rate of runoff making adjustments as required for percent
of impervious cover, alterations to hydraulic length and percentage
of watershed and wetland as described in TR-55 and supplemented by
notes provided by the Soil Conservation Service. The tabular method
described in TR-55 shall be used for calculating runoff rates.
(b)
The total quantity of runoff utilizing the tabular hydrographic
data contained in TR-55. Total quantities of runoff shall be estimated
prior to and after development by calculating the total area under
the hydrograph utilizing the hydrographic coefficients contained in
TR-55.
(c)
The relative timing of the peak rate of discharge following
the onset of a storm shall be identified within the stormwater calculations.
(11)
Retention basins, detention basins and partial detention basins
shall be sized by routing each of the required design storms using
either reservoir routing or graphical methods.
(12)
For storm sewer design, the rational method (Q=CIA) may be utilized
for calculating runoff quantities subject to the following criteria.
The minimum design requirements for storm sewers shall be the ten-year
storm. Runoff generated by storms of greater intensity, up to and
including the fifty-year storm, shall be directed towards detention
basins or alternative stormwater facilities on the site:
(a)
The rainfall intensity (I) shall be computed as a function of
the time of concentration by generally accepted procedures found in
Seeyles, algebraic equations, the Soil Conservation Service Engineering
Field Manual, etc.
(b)
The area (A) shall include all off-site acreage draining onto
or through the site.
(c)
The coefficient of runoff (C) shall not be less than the values
stated below unless well documented and approved by the Engineer:
|
Surface
|
Minimum "C"
|
|---|---|
|
Structures, pavements
|
0.90
|
|
Cultivated dense or clay soils
|
0.30
|
|
Cultivated sand or loam soils
|
0.25
|
|
Meadows, rural areas
|
0.20
|
|
Heavily wooded areas
|
0.15
|
|
Overall drainage runoff factors will not, in general, be less
than the following:
|
|
Proposed Development
| |
|---|---|
|
Site Plans
|
Minimum "C"
|
|
(To the limits of improvements)
|
0.70
|
|
1/4 acre residential
|
0.50
|
|
1/2 acre residential
|
0.40
|
|
1 acre residential
|
0.30
|
|
NOTE: The above tables are intended as minimum design standards.
They are not mandated design criteria
|
(d)
Velocities will be computed using Manning's equation or generally
accepted nomographs for pipe flow. Pipes shall be designed flowing
full without head conditions for the ten-year storm (minimum).
(f)
Other cross sections or pipe materials shall have commensurate
friction factors as may be approved by the City Engineer or consultant.
B.
Methods of calculating stormwater runoff quality.
(1)
In complying with the stormwater runoff quality standards in § 238-5G(4), the design engineer shall calculate the stormwater runoff rate and volume using the USDA Natural Resources Conservation Service (NRCS) Runoff Equation, Runoff Curve Numbers, and Dimensionless Unit Hydrograph, as described in the NRCS National Engineering Handbook Part 630 — Hydrology and Technical Release 55, Urban Hydrology for Small Watersheds, as amended and supplemented.
(2)
The design engineer shall also use the NJDEP water quality design
storm, which is 1 1/4 inches of rainfall falling in a nonlinear
pattern in two hours. Details of the water quality design storm are
shown in Table 1 below.
(3)
Calculation of runoff volumes, peak rates, and hydrographs for the
water quality design storm may take into account the implementation
of nonstructural and structural stormwater management measures.
|
Table 1: Water Quality Design Storm Distribution
| |
|---|---|
|
Time
(minutes)
|
Cumulative Rainfall
(inches)
|
|
0
|
0.0000
|
|
5
|
0.0083
|
|
10
|
0.0166
|
|
15
|
0.0250
|
|
20
|
0.0500
|
|
25
|
0.0750
|
|
30
|
0.1000
|
|
35
|
0.1330
|
|
40
|
0.1660
|
|
45
|
0.2000
|
|
50
|
0.2583
|
|
55
|
0.3583
|
|
60
|
0.6250
|
|
65
|
0.8917
|
|
70
|
0.9917
|
|
75
|
1.0500
|
|
80
|
1.0840
|
|
85
|
1.1170
|
|
90
|
1.1500
|
|
95
|
1.1750
|
|
100
|
1.2000
|
|
105
|
1.2250
|
|
110
|
1.2384
|
|
115
|
1.2417
|
|
120
|
1.2500
|
|
Source N.J.A.C. 7:8-5.5(d)
|
(4)
Total suspended solids (TSS) reduction calculations.
(a)
If more than one stormwater 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
|
(5)
TSS removal rates for stormwater BMPs.
(a)
For purposes of TSS reduction calculations, Table 2 presents the presumed removal rates for certain BMPs designed in accordance with the New Jersey BMP Manual. The BMP Manual may be obtained from the address identified in § 238-11 or found on the NJDEP's website at www.njstormwater.org. TSS reduction shall be calculated based on the removal rates for the BMPs in Table 2.
(b)
Alternative stormwater management measures, 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 City. Any alternative stormwater management
measure, removal rate or method of calculating the removal rate shall
be subject to approval by the City, and a copy shall be provided to
the following:
[1]
The Division of Watershed Management, New Jersey Department
of Environmental Protection, PO Box 418, Trenton, NJ, 08625-0418.
|
Table 2: Pollutant Removal Rates for BMPs
| |||
|---|---|---|---|
|
Best Management Practice
|
TSS Percent Removal Rate
|
Total Phosphorus Percent Removal Rate
|
Total Nitrogen Percent Removal Rate
|
|
Bioretention systems
|
90
|
60
|
30
|
|
Constructed stormwater wetland
|
90
|
50
|
30
|
|
Extended detention basin
|
40-60 (final rate based upon detention time; see New Jersey
BMP Manual, Chapter 9)
|
20
|
20
|
|
Infiltration basin
|
80
|
60
|
50
|
|
Manufactured treatment device
|
Pollutant removal rates as certified by NJDEP; see § 238-8A(2)(i).
|
Pollutant removal rates as certified by NJDEP; see § 238-8A(2)(i).
|
Pollutant removal rates as certified by NJDEP; see § 238-8A(2)(i).
|
|
Pervious paving systems
|
80 (porous paving)
|
60
|
50
|
|
80 (permeable pavers with storage bed)
|
0 - volume reduction only (permeable pavers without storage
bed)
|
0 - volume reduction only (permeable pavers without storage
bed)
| |
|
0 - volume reduction only (permeable pavers without storage
bed)
| |||
|
Sand filter
|
80
|
50
|
35
|
|
Vegetative filter strip
(For filter strips with multiple vegetated covers, the final
TSS removal rate should be based upon a weighted average of the adopted
rates shown in Table 2, based upon the relative flow lengths through
each cover type.)
|
60 (turf grass)
|
30
|
30
|
|
70 (native grasses, meadow and planted woods)
| |||
|
80 (indigenous woods)
| |||
|
Wet pond/retention basin
|
50-90 (final rate based upon pool volume and detention time;
see NJ BMP Manual)
|
50
|
30
|
|
Source: N.J.A.C. 7:8-5.5(c) and New Jersey BMP Manual Chapter
4.
|
(6)
Nutrient removal rates for stormwater BMPs. For purposes of postdevelopment nutrient load reduction calculations, Table 2 presents the presumed removal rates for certain BMPs designed in accordance with the New Jersey BMP Manual. If alternative stormwater BMPs are proposed, the applicant shall demonstrate that the selected BMPs will achieve the nutrient removal standard required in § 238-5G.
C.
Groundwater recharge may be calculated in accordance with the following:
(1)
In complying with the groundwater recharge requirements in § 238-5G, the design engineer shall calculate groundwater recharge in accordance with the New Jersey Groundwater Recharge Spreadsheet (NJGRS) computer program incorporated herein by reference, as amended and supplemented. Information regarding the methodology is available in § 238-5 or from the New Jersey BMP Manual.
(2)
Alternative groundwater recharge calculation methods to meet these
requirements may be used upon approval by the City Engineer.
(3)
In complying with the groundwater recharge requirements in § 238-5, the design engineer shall:
(a)
Calculate stormwater runoff volumes in accordance with the USDA
Natural Resources Conservation Service (NRCS) methodology, including
the NRCS Runoff Equation and Runoff Curve Numbers, as described in
the NRCS National Engineering Handbook Part 630 — Hydrology
and Technical Release 55, Urban Hydrology for Small Watersheds, as
amended and supplemented; and
(b)
Use appropriate two-year, twenty-four-hour rainfall depths as
developed for the project site by the National Oceanic and Atmospheric
Administration, available online at http://hdsc.nws.noaa.gov/hdsc/pfds/index.html.
(4)
When calculating groundwater recharge or stormwater runoff for predeveloped
site conditions, the design engineer shall use the following criteria:
(a)
When selecting land covers or calculating runoff curve numbers
(CNs) for predeveloped project site conditions, the project site's
land cover shall be assumed to be woods. However, another land cover
may be used to calculate runoff coefficients if:
[1]
Such land cover has existed at the site or portion thereof without
interruption for at least five years immediately prior to the time
of application; and
[2]
The design engineer can document the character and extent of
such land cover through the use of photographs, affidavits, and/or
other acceptable land use records.
(b)
If more than one land cover, other than woods, has existed on
the site during the five years immediately prior to the time of application,
the land cover with the lowest runoff potential (including woods)
shall be used for the computations.
(c)
All predeveloped land covers shall be assumed to be in good
hydrologic condition and, if cultivated, shall be assumed to have
conservation treatment.
A.
Nonstructural stormwater management strategies incorporated into
site design shall:
(1)
Protect areas that provide water quality benefits or areas particularly
susceptible to erosion and sediment loss;
(2)
Minimize impervious surfaces and break up or disconnect the flow
of runoff over impervious surfaces;
(3)
Maximize the protection of natural drainage features and vegetation;
(4)
Minimize the decrease in the time of concentration from preconstruction
to postconstruction. "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;
(5)
Minimize land disturbance, including clearing and grading;
(6)
Minimize soil compaction;
(7)
Provide low-maintenance landscaping that encourages retention and
planting of native vegetation and minimizes the use of lawns, fertilizers
and pesticides;
(8)
Provide vegetated open-channel conveyance systems discharging into
and through stable vegetated areas;
(9)
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:
(a)
Site design features that help to prevent accumulation of trash
and debris in drainage systems;
(b)
Site design features that help to prevent discharge of trash
and debris from drainage systems;
(c)
Site design features that help to prevent and/or contain spills
or other harmful accumulations of pollutants at industrial or commercial
developments; and
(d)
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.
(10)
Blocks and lots shall be graded to secure proper drainage away
from all buildings and to prevent the collection of stormwater in
pools and to avoid concentration of stormwater from each lot to adjacent
lots.
B.
Site design features identified under § 238-6A, or alternative designs in accordance with § 238-5H(2), to prevent discharge of trash and debris from drainage systems shall comply with the following standard to control passage of solid and floatable materials through storm drain inlets. For purposes of this subsection, "solid and floatable materials" means sediment, debris, trash, and other floating, suspended, or settleable solids.
(1)
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:
(a)
The New Jersey Department of Transportation (NJDOT) bicycle-safe
grate, which is described in Chapter 2.4 of the NJDOT Bicycle Compatible
Roadways and Bikeways Planning and Design Guidelines; or
(b)
A different grate, if each individual clear space in that grate
has an area of no more than 7.0 square inches, or is no greater than
0.5 inch 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.
(2)
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 square inches, or be no greater than two inches across
the smallest dimension. Curb-opening inlet grates shall be consistent
with standardized casting specifications as approved by the City Engineer.
(3)
This standard does not apply:
(a)
Where each individual clear space in the curb opening in an
existing curb-opening inlet does not have an area of more than 9.0
square inches;
(b)
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;
(c)
Where flows from the water quality design storm as specified in § 238-5G(4)(a) are conveyed through any device (e.g., end-of-pipe netting facility, manufactured treatment device, or a catch basin hood) that is designed, at a minimum, to prevent delivery of all solid and floatable materials that could not pass through one of the following:
[1]
A rectangular space 4 5/8 inches long and 1 1/2 inches
wide (this option does not apply for outfall netting facilities);
or
[2]
A bar screen having a bar spacing of 0.5 inch.
Note that these exemptions do not authorize any infringement
of requirements in the Residential Site Improvement Standards for
bicycle-safe grates in new residential development (N.J.A.C. 5:21-4.18(b)2
and 7.4(b)1).
(d)
Where flows are conveyed through a trash rack that has parallel bars with one-inch spacing between the bars, to the elevation of the water quality design storm as specified in § 238-5; or
(e)
Where the New Jersey Department of Environmental Protection
determines, pursuant to the New Jersey Register of Historic Places
Rules at N.J.A.C. 7:4-7.2(c), that action to meet this standard is
an undertaking that constitutes an encroachment or will damage or
destroy the New Jersey Register listed historic property.
A.
General design and construction standards.
(1)
Structural stormwater management measures shall be designed to meet
the standards established in this section. These standards have been
developed to protect public safety, conserve natural features, create
an aesthetically pleasing site and promote proper on-site stormwater
management.
(2)
The following structural stormwater management measures may be utilized
as part of a stormwater management system at a land development, provided
that the applicant demonstrates that they are designed, constructed
and maintained so as to meet the standards and requirements established
by this chapter. If alternative stormwater management measures are
proposed, the applicant shall demonstrate that the selected measures
will achieve the standards established by this chapter.
(a)
Bioretention systems: Bioretention systems are designed to aid
in the removal of suspended solids, nutrients, metals, hydrocarbons
and bacteria from stormwater runoff.
[1]
The use of bioretention systems should be used as a secondary
stormwater management structure. Bioretention systems should be located
as close to the area of runoff as possible with runoff entering the
system through overland flow. Bioretention systems may be placed in
lawns, median strips, parking lot islands, unused lots and certain
easements.
[2]
Bioretention systems must not be placed in operation until the
site was been completely stabilized.
[3]
Bioretention systems should only be used in areas of well draining
soils.
(b)
Constructed stormwater wetlands: Constructed stormwater wetlands
are designed to remove suspended solids, nutrients and bacteria from
stormwater runoff and provide wildlife habitat.
(c)
Dry wells: Dry wells and porous pipes are designed to infiltrate
the runoff from small drainage areas, such as roof structures. These
structures supply a means to remove pollutants and provide infiltration
when space is limited.
[1]
Such devices should be used in areas of well draining soils
and in cases where there is sufficient separation between the seasonal
high-water table and the bottom of the infiltration device.
(d)
Extended detention basins: Extended detention basins provide
a means to control stormwater quantity and quality concerns. The lower
stages of the basin provide measures to control the stormwater quality
storm, while higher stages in the basin can attenuate the peak rates
of runoff from larger storms.
[1]
Such devices are most suitable in cases where there is a significant
increase in the amount of runoff. Extended detention basins require
a significant amount of room and depth to provide proper performance.
(e)
Vegetated filters: Vegetated filter strips area designed to
remove various pollutants such as suspended solids by providing runoff
a flow path over a vegetated area. Such areas can be developed in
grass-lined waterways or swales and be primarily grass, or larger
areas may be primarily composed of woods and brush.
[1]
Grass-lined waterways are a viable option for stormwater conveyance,
especially to secondary devices such as infiltration/detention basins.
Such areas help promote the lifespan of basins by removing suspended
solids before runoff reaches and settles on basin bottoms.
[2]
Large vegetated filters such as areas of woods and dense grass
may be used alone in small areas of development or in areas where
the amount of impervious cover will not be drastically increased.
(f)
Infiltration basins and trenches: Infiltration basins are designed
to remove certain pollutants and to infiltrate stormwater. Infiltration
basins provide a means to reduce both the peak rate and total volume
of runoff caused by land development.
(g)
Wet ponds with suitable liners: Wet ponds should be used as
landscape devices providing minimal stormwater quantity control. Some
quality control can be expected; however, this type of facility should
not be your only form of stormwater control.
(h)
Pervious paving systems: Pervious pavements act as infiltration
systems providing infiltration either through a pervious paving surface
course or through void spaces between individual paving blocks or
pavers. Such systems offer enhanced infiltration performance and some
pollutant removal.
[1]
Such devices should not be used in industrial and commercial
areas where solvents and/or petroleum products are loaded, unloaded,
stored or applied or pesticides are loaded, unloaded, or stored.
[2]
The use of such devices should be limited around building structures
where enhanced infiltration could cause basement seepage or flooding.
[3]
Due to reduced shear strength of the surface course, pervious
paving surface should be limited to areas of low traffic volumes and
weight, such as: secondary aisles in parking lots, single-family driveways,
sidewalks and walkways, golf cart paths, and overflow parking areas.
(i)
Manufactured treatment devices, provided their pollutant removal
rates are verified by the New Jersey Corporation for Advanced Technology
and certified by the NJDEP.
(3)
Structural stormwater management measures shall be designed to take
into account the existing site conditions, including environmentally
critical areas, wetlands, flood-prone areas, slopes, depth to seasonal
high-water table, soil type, permeability and texture, and drainage
area and drainage patterns.
(4)
Structural stormwater management measures shall be designed and constructed
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 7.8 shall be deemed to meet
this requirement); to minimize and facilitate maintenance and repairs;
and to ensure proper functioning.
(5)
For all stormwater management measures at a development site, each applicant shall submit a detailed inspection, maintenance and repair plan consistent with the requirements of § 238-14 of this chapter.
(6)
To the maximum extent practicable, the design engineer shall design
structural stormwater management measures on the development site
in a manner that:
(a)
Limits site disturbance, maximizes stormwater management efficiencies,
and maintains or improves aesthetic conditions;
(b)
Utilizes multiple stormwater management measures, smaller in
size and distributed spatially throughout the land development site,
instead of a single larger structural stormwater management measure;
(c)
Incorporates pretreatment measures. Pretreatment can extend
the functional life and increase the pollutant removal capability
of a structural stormwater management measure. Pretreatment measures
may be designed in accordance with the New Jersey BMP Manual or other
sources approved by the City Engineer.
(7)
Stormwater management basins shall be designed in a manner that complements
and mimics the existing natural landscape, including but not limited
to the following design strategies:
(8)
Structural stormwater management measures shall be designed to minimize
maintenance, facilitate maintenance and repairs, and ensure proper
functioning.
(9)
In many instances, the provisions of separate detention facilities
for a number of single sites may be more expensive and more difficult
to maintain than provisions of joint facilities for a number of sites.
In such cases, the City will be willing to consider provisions of
joint detention facilities which will fulfill the requirements of
this regulation. In such cases, a properly planned staged program
of detention facilities may be approved by the City.
(10)
The location of a retention system that is approved in lieu
of detention facilities shall be in areas with seasonal high water
a minimum of two feet below the lowest elevation of the facility.
Where the bottom of any proposed retention basin is less than two
feet above impervious soil formations, the use of vertical drains
or other methods, subject to the approval of the Engineer, may be
employed, provided that the water quality is addressed.
(11)
In establishing the location and constructing basins, every
effort shall be made to utilize existing contours and depressions.
(12)
Guidance on the design and construction of structural stormwater
management measures may be found in the New Jersey BMP Manual. Other
guidance sources may also be used upon approval by the City Engineer.
(13)
After all construction activities and required field testing
have been completed on the development site, as-built plans depicting
design and as-built elevations of all stormwater management measures
shall be prepared by a licensed land surveyor and submitted to the
City Engineer in paper and electronic format acceptable to the City
Engineer. Based upon the City Engineer's review of the as-built plans,
all corrections or remedial actions deemed by the City Engineer to
be necessary due to the failure to comply with the standards established
by this chapter and/or any reasons of public health or safety shall
be completed by the applicant. In lieu of review by the City Engineer,
the City of Linwood reserves the right to engage a professional engineer
to review the as-built plans. The applicant shall pay all costs associated
with such review. Review costs shall be guaranteed through the establishment
of an escrow posted by the applicant in accordance with the provisions
of the Municipal Land Use Law (N.J.S.A. 40:55D-1 et seq.).
B.
Standards for detention basins are as follows:
(1)
At the intake to the outlet from the stormwater management basin,
the orifice size shall be a minimum of three inches in diameter.
(2)
Stormwater management basins shall be designed with gently sloping
sides. The maximum allowable basin side slope shall be three horizontal
to one vertical (3:1).
(4)
Outlet waters, including that from a design storm with a recurrence
interval of 100 years, shall be discharged from the development at
such locations and velocities as to not cause additional erosion or
cause additional channels beyond the development from those natural
or other drainageways available before development.
(5)
The location of a detention facility shall be in an area with seasonal
high water a minimum of 2.0 feet below the lowest invert elevation
of the facility.
(6)
All detention basins must maximize to the extent practicable the
distance between basin inflow and outflow. A slope of 1% shall be
provided from inlet to outlet.
(7)
Water-tolerant species of vegetative cover for detention basin usage
must be employed. Suggested varieties of cover include reed, canary
grass, fescue, perennial rye, orchard grass and Bermuda grass.
(8)
Outlets from detention facilities shall be designed to function without
manual, electric or mechanical controls.
(9)
If detention basins are provided through which water passes at times
other than following rainfall, the City Engineer should be consulted
concerning design criteria. It will be necessary for detention requirements
to be met, despite the necessity of passing certain low flows. This
applies to all online detention basins.
(10)
A low-flow channel shall be incorporated into the detention
basin to prevent broad area ponding.
(11)
Stabilized access 20 feet wide is to be provided to the detention
facility capable of supporting maintenance vehicles.
(12)
During construction, all basins shall be lined with filter fabric
to prevent the siltation of subsurface soils. After completion of
the proposed development, the fabric shall be inspected on a regular
basis and removed or replaced, if necessary.
(13)
At inflow points to detention basins, energy dissipaters, designed
in accordance with the current Soil Conservation Service standards
for soil erosion and sediment control, must be incorporated to reduce
the velocity of inflowing waters.
(14)
The design of the facility should be based upon peak rates of
runoff for the entire drainage area upstream from the parcel in question,
and the design release rates should be computed on the basis of preexisting
conditions for the entire watershed.
C.
Standards for retention/infiltration basins shall incorporate all
of the standards listed above for detention basins except for outlet
design with the addition of the following:
(1)
A retention basin system must accommodate stormwater runoff so that
the minimum rate of percolation of the soil is 15 minutes per inch,
which allows infiltration of 36 inches of runoff over a three-day
period from the basin.
(2)
The location of a retention facility shall be in an area with seasonal
high water a minimum of two feet below the lowest invert elevation
of the facility. The bottom of any proposed basin shall be at least
five feet above any impervious soil formations found in the soil logs
or otherwise the impervious layer shall be penetrated at required
intervals.
(3)
Sediment traps must be located such that all inflowing stormwater
is treated before entering any subsurface recharge system.
(4)
Soil within the recharge system shall be protected with filter fabric
during construction; then, when site construction is complete, the
filter fabric shall be removed and basin soils stabilized.
(5)
A low-flow channel shall be incorporated into the retention basin
to prevent broad area ponding.
(6)
Stabilized access 20 feet wide is to be provided to the retention
facility capable of supporting maintenance vehicles.
(7)
The retention of site runoff as required by this chapter will result
in the accumulation of sediment, including particulate silt and debris.
Provision must be made for periodic removal of accumulated solid materials
such that the basin continues to operate as designed.
(8)
Infiltration practices, such as dry well, infiltration basins, infiltration
trenches, buffer strips, etc., may be used to satisfy this requirement,
provided that they produce zero runoff from the water quality design
storm and allow for complete infiltration within 36 hours.
D.
Standards for detention/infiltration basins in flood hazard areas
shall meet or exceed all standards as listed in the above two sections
with the additional requirements as listed below:
(1)
Whenever practicable, developments and their stormwater facility
basins should be located outside the extent of Zone A5, flood hazard
boundary. When this is not possible and facility basins are located
partially or wholly within Zone A5 (as defined by New Jersey Division
of Water Resources, Bureau of Flood Plain Management), some storm
conditions will make the facility ineffective at providing retention
of site runoff. This will happen if the stream is already overflowing
its banks and the basin, causing the basin to be filled prior to the
time it is needed for containment of runoff. In such cases, the standards
established in these regulations will be modified in order to give
only partial credit to detention capacities located within the A5
Zones. The credit will vary in a ratio intended to reflect the probability
that storage will be available at the time a storm occurs at the site.
(2)
Stormwater runoff storage parameters shall be based upon the location
and elevation of said facility. If a facility is located on the edge
or within the base flood elevation (A5 Zone), the following criteria
shall be used to determine effective storage:
(a)
When the bottom of the stormwater facility is less than two
feet below the base flood elevation, a storage volume of 2 1/2
times the calculated site runoff storage volume must be accommodated
by the basin.
(b)
When the bottom of the stormwater facility is between two feet
and four feet below base flood elevation, a storage volume of four
times the calculated site runoff storage volume must be accommodated
by the basin.
(c)
When the bottom of the said facility is four feet or more below
the base flood elevation, a storage volume of 10 times the calculated
site runoff storage volume must be provided by the basin.
(3)
As an alternative approach to the above criteria, if the developer
can demonstrate that the detention provided would be effective, during
runoff from the twenty-five-year, twenty-four-hour Type III storm,
peaking simultaneously at the site and on the flood hazard area, his
plan will be accepted as complying with provisions in the above set
criteria.
E.
Landscaping. All detention and retention-infiltration basins shall be landscaped in accordance with Chapter 7 of the New Jersey Stormwater Best Management Practices Manual.
F.
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 § 238-4 of this chapter.
G.
Drainage structures and stormwater conveyance systems are required
to meet the following standards:
(1)
All drainage structures, including manholes, inlets, headwalls and
sections and box culverts, shall conform to the current details of
the New Jersey Department of Transportation. Unless approved otherwise
by the Engineer, all curb inlets shall be standard Type B with curb
piece heights equal to the exposed curb face of the adjacent curb
plus two inches. All lawn inlets shall be standard Type E. When the
pipe size is such as to require a larger structure, standard Type
B1 or B2, E1 and E2 shall be used. If still larger sizes are required,
they shall be specifically detailed using standard frames and grates.
(2)
Type B street inlets shall have the "J-ECO" casting or approved equal.
All street inlets shall be constructed with a bicycle safe grate.
(3)
Dished gutters on local streets shall be permitted only at T intersections
involving local streets. Dished gutters shall not be permitted on
arterial or collector streets.
(4)
Storm drain pipes running longitudinally along streets shall not
be located under curbing.
(5)
Storm drainage pipe shall be concrete unless an alternate is approved.
If an alternate is considered, it may be corrugated round, arch or
helical. All pipe shall be of the size specified and laid to the exact
lines and grades approved. Reinforced concrete pipe shall conform
to ASTM Specification C76. All pipe shall be Class 111 strength, except
where stronger pipe is required. Joints shall have O-ring rubber gaskets,
where necessary. Steel, aluminum or other pipe shall meet the latest
American Association of State Highway and Transportation Officials
standard.
(a)
All storm sewer systems shall have a design capacity equal to
or greater than the volume of runoff generated by the ten-year, twenty-four-hour
Type III storm event. The minimum pipe diameter shall be 15 inches.
The maximum distances between manholes or inlets shall be 500 feet.
(b)
Pipe crown elevations shall be matched in all manholes and inlets.
In general, a cover of one diameter shall be maintained over the drainage
pipe. If this is not possible, a higher class pipe must be specified
or trench conditions must be designed and detailed to ensure at least
85% relative compaction.
(c)
Inlets shall be specified with cast curb piece inlets attached.
Inlets shall be depressed one or two inches to increase capacities
on steep grades (6% or more).
(d)
The minimum design velocity when flowing 1/4 full shall be at
least two feet per second, but no more than 10 feet per second. Pipes
shall be considered flowing full at maximum capacity.
(e)
Single Type B inlets shall not be designed to catch more than
5 1/2 cubic feet per second, regardless of head.
(f)
Concrete pipe shall be utilized beneath roadways and parking
areas.
A.
Applicants seeking a variance or exemption from the stormwater management
design and performance standards stated herein may, at the City's
discretion, provide off-site mitigation measures subject to the following:
(1)
The mitigation project must be implemented in the same drainage area as the proposed development. The project must provide additional groundwater recharge benefits, or protection from stormwater runoff quality and quantity from previously developed property that does not currently meet the design and performance standards defined herein. The developer must ensure the long-term maintenance of the project, including maintenance requirements specified under § 238-14.
(a)
The Planning Board may direct an applicant seeking variance
or waiver relief to perform all or a portion of the work identified
in any mitigation projects to compensate for a deficit from the performance
standards resulting from the proposed project. Potential mitigation
projects shall be as designated by the City Engineer.
(2)
If a suitable site cannot be located in the same drainage area as the proposed development, as discussed in Subsection A(1) above, the mitigation project may provide mitigation that is not equivalent to the impacts for which the variance or exemption is sought, but that addresses the same issue. For example, if a variance is given because the 80% TSS requirement is not met, the selected project may address water quality impacts due to a fecal impairment.
B.
The municipality may allow a developer to provide funding or partial
funding to the municipality for an environmental enhancement project
that has been identified in the City's municipal stormwater management
plan or towards the development of a regional stormwater management
plan. The funding must be equal to or greater than the cost to implement
the mitigation measures, including costs associated with the long-term
maintenance requirements of the mitigation measure.
A.
A minimum of two test pits shall be required for all detention, retention
or other stormwater facilities. For all basins with a surface area
of 1/2 acre or more, test pits will be required at a rate of one test
pit for each 1/2 acre in excess of the initial minimum of two test
pits per facility. All test pits must extend at least five feet below
the bottom of any proposed detention facility and 10 feet below the
bottom of any retention/infiltration facility. Soil boring information
shall be displayed on preliminary plans and shall include:
(1)
The soil texture as described in the United States Department of
Agriculture Soil Texture Classification System.
(2)
The soil colors as described in the Munsell Color Chart.
(3)
The estimated depth of seasonal high groundwater based on mottling
characteristics of the soil.
(4)
The depth of static water level at the time of boring.
(5)
The vegetation types immediately surrounding the area.
B.
Percolation/permeability tests. At least one percolation or permeability
test shall be performed at the site of each basin or disposal area.
The percolation/permeability tests shall be performed at a depth corresponding
to the approximate bottom of the basin or infiltration facility.
C.
Fill material. Fill material used for stormwater facilities shall
have a percolation/permeability rate equal to or greater than the
existing soils. All fill material shall meet or exceed the quality
of the existing soil. Fill shall be as free of clay soils as possible.
A.
Technical guidance for stormwater management measures can be found in the documents listed in Subsection A(1) and (2) below, which are available to download from the Department's website at: http://www.nj.gov/dep/stormwater/bmp_manual2.htm.
(1)
Guidelines for stormwater management measures are contained in the
New Jersey Stormwater Best Management Practices Manual, as amended.
Information is provided on stormwater management measures such as,
but not limited to: 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.
(3)
Additional maintenance guidance is available on the Department's
website at: http://www.njstormwater/org/maintenance_guidance.htm.
B.
Additional technical guidance for stormwater management measures
can be obtained from the following:
(1)
The Standards for Soil Erosion and Sediment Control in New Jersey,
promulgated by the State Soil Conservation Committee and incorporated
into N.J.A.C. 2:90. Copies of these standards may be obtained by contacting
the State Soil Conservation Committee or any of the soil conservation
districts listed in N.J.A.C. 2:90-1.3(a)3. The location, address,
and telephone number of each soil conservation district may be obtained
from the State Soil Conservation Committee, P.O. Box 330, Trenton,
New Jersey, 08625, (609) 292-5540;
(2)
The Rutgers Cooperative Extension Service, (732) 932-9306; and
(3)
The soil conservation districts listed in N.J.A.C. 2:90-1.3(a)3.
The location, address, and telephone number of each soil conservation
district may be obtained from the State Soil Conservation Committee,
P.O. Box 330, Trenton, New Jersey, 08625, (609) 292-5540.
C.
Submissions required for review by the Department should be mailed
to the Division of Water Quality, New Jersey Department of Environmental
Protection, Mail Code 401-02B, PO Box 420, Trenton, New Jersey 08625-0420.
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 stormwater management BMP.
B.
Requirements for trash racks, overflow grates and escape provisions.
(1)
A trash rack is a device designed to catch trash and debris and prevent
the clogging of outlet structures. Trash racks shall be installed
at the intake to the outlet from the stormwater management BMP to
ensure proper functioning of the BMP outlets in accordance with the
following:
(a)
The trash rack shall have parallel bars, with no greater than
six-inch spacing between the bars.
(b)
The trash rack shall be designed so as not to adversely affect
the hydraulic performance of the outlet pipe or structure.
(c)
The average velocity of flow through a clean trash rack is not
to exceed 2.5 feet per second under the full range of stage and discharge.
Velocity is to be computed on the basis of the net area of opening
through the rack.
(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 pounds per square foot.
(2)
An overflow grate is designed to prevent obstruction of the overflow
structure. If an outlet structure has an overflow grate, such grate
shall meet the following requirements:
(a)
The overflow grate shall be secured to the outlet structure
but removable for emergencies and maintenance.
(b)
The overflow grate spacing shall be no less than two inches
across the smallest dimension.
(c)
The overflow grate shall be constructed and installed to be
rigid, durable, and corrosion resistant and shall be designed to withstand
a perpendicular live loading of 300 pounds per square foot.
(3)
For purposes of this subsection, "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 BMPs shall include escape provisions as follows:
(a)
If a stormwater management BMP has an outlet structure, escape provisions shall be incorporated in or on the structure. With the prior approval of the reviewing agency identified in § 238-12C, a freestanding 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 2 1/2 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 2 1/2 feet below the permanent water surface, and the second step shall be located 1 1/2 feet above the permanent water surface. See § 238-12D 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
three horizontal to one 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 (City, county or Department) that the
variance or exemption will not constitute a threat to public safety.
D.
Illustration of safety ledges in a new stormwater management basin.
 |
A.
Submission of site development stormwater plan.
(1)
Whenever an applicant seeks City approval of a development subject to this chapter, the applicant shall submit all of the required components of the checklist for the site development stormwater plan at § 238-13C 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 chapter.
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 City board or official from whom City approval
is sought. That City board or official shall consult the engineer
retained by the Planning 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 chapter.
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 one inch equals 200 feet or greater, showing two-foot
contour intervals. The map, as appropriate, may indicate the following:
existing surface water drainage, shorelines, steep slopes, soils,
erodible soils, perennial or intermittent streams that drain into
or upstream of the Category One waters, wetlands and floodplains along
with their appropriate buffer strips, marshlands and other wetlands,
pervious or vegetative surfaces, existing man-made structures, roads,
bearing and distances of property lines, and significant natural and
man-made 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 groundwater 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 §§ 238-3 through 238-6 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. Comprehensive hydrologic and hydraulic design calculations for the predevelopment and postdevelopment conditions for the design storms specified in § 238-6 of this chapter. When the proposed stormwater management control measures depend on the hydrologic properties of soils or require certain separation from the seasonal high water table, then a soils report shall be submitted. The soils report shall be based on on-site boring logs or soil pit profiles. The number and location of required soil borings or soil pits shall be determined based on what is needed to determine the suitability and distribution of soils present at the location of the control measure.
(7)
Maintenance and repair plan. The design and planning of the stormwater management facility shall meet the maintenance requirements of § 238-14.
(8)
Soil investigation report. Soils report must contain the results
from subsurface investigations, including test pits and borings along
with the results for percolation and permeability. The locations of
the tests should be clearly labeled on plans.
(9)
Waiver from submission requirements. The City official or board reviewing an application under this chapter may, in consultation with the City Engineer, waive submission of any of the requirements in § 238-13C(1) through (6) of this chapter 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.
General maintenance.
(1)
Responsibility for operation and maintenance of all facilities, including
periodic removal and disposal of accumulated particulate material
and debris, shall remain with the owner or owners of the property,
with permanent arrangements that shall pass to any successive owner,
unless assumed by a government agency. If portions of the land are
to be sold, legally binding arrangements shall be made to pass the
basic responsibility to successors in title. These arrangements shall
designate for each project the property owner, governmental agency
or other legally established entity to be permanently responsible
for maintenance.
(a)
The design engineer shall prepare a maintenance plan for the
stormwater management measures incorporated into the design of a development.
(b)
The maintenance plan shall contain specific preventative maintenance
tasks and schedules; cost estimates, including estimated cost of sediment,
debris, or trash removal, manpower, capital cost of equipment, and
repair costs; and the name, address, and telephone number of the person
or persons responsible for preventative and corrective maintenance
(including replacement). This plan shall contain information on BMP
location, design, ownership, maintenance tasks and frequencies, and
other details as specified in Chapter 9 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. 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.
(c)
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. The individual property
owner 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 legally responsible for all
of the maintenance required.
(d)
If the person responsible for maintenance identified under § 238-14B(1) above is not a public agency, the maintenance plan and any future revisions shall be recorded upon the deed of record for each property on which the maintenance described in the maintenance plan must be undertaken.
(e)
Preventative and corrective maintenance shall be performed to
maintain the function of the stormwater management measure, including
repairs to or replacement of 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.
(f)
The person responsible for maintenance identified under § 238-14B(1) 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.
(g)
The person responsible for maintenance identified under § 238-14B(1) above shall evaluate the effectiveness of the maintenance plan at least once per year and adjust the plan and the deed as needed.
(h)
The person responsible for maintenance identified under § 238-14B(1) 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 this section.
(i)
The requirements of § 238-14B(1)(f), (g) and (h) do not apply to stormwater management facilities that are dedicated to and accepted by the City or another governmental agency, subject to all applicable municipal stormwater general permit conditions, as issued by the Department.
(j)
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 City shall so notify the responsible person
in writing. Upon receipt of that notice, the responsible person shall
have 14 days to effect maintenance and repair of the facility in a
manner that is approved by the City Engineer or his designee. The
City, 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 City may immediately
proceed to do so and shall bill the cost thereof to the responsible
person. Nonpayment of such bill may result in a lien on the property.
(k)
Prior to the granting of any site development approval, the
applicant shall enter into an agreement (declaration of covenants
and restrictions for drainage structures) with the City to ensure
the continued operation and maintenance of the stormwater facility
unless the City has consented to accept the facility as City property.
This agreement shall be in a form satisfactory to the City Attorney
and may include, but may not necessarily be limited to, personal guarantees,
deed restrictions, covenants and bonds. In cases where the property
is subdivided and sold separately, a homeowners' association or similar
permanent entity shall be established as the responsible entity, absent
an agreement by a governmental agency to assume responsibility. The
agreement shall also provide for regular inspection at the expense
of the applicant, or the applicant's successors in interest, and for
the undertaking by the applicant and successors of such corrective
measures as are shown by such inspection to be required for the proper
functioning of the facilities. The agreement shall provide, among
other things, that the applicant shall provide up to a four-year maintenance
guarantee for the entire stormwater management system, which shall
commence at the conclusion of the period required for such performance
guarantee as required by the Board. The agreement shall also provide
for an inspection and maintenance program of up to 10 years in duration.
(l)
The applicant must obtain approval from the Engineer for all arrangements and values described in Subsection B(1)(b).
(m)
The applicant must deliver an easement for a clear accessway
of 20 feet to all stormwater facilities for the purpose of assuring
vehicular access for maintenance activities.
(2)
Nothing in this section shall preclude the City from requiring the
posting of a performance and/or maintenance guarantee in accordance
with N.J.S.A. 40:55D-53.
A.
When excavated and completed, the design engineer shall certify in
writing to the City that the stormwater facility will operate as intended
in the design phase, taking into consideration all soil and water
conditions encountered during construction. As-built percolation test
results shall also be provided if the basin has been used as a place
for sediment accumulation during the construction process.
B.
Both retention and detention basins shall have the following improvements
as further specified in the New Jersey Department of Transportation
Standard Specifications for Road and Bridge Construction, as amended,
and New Jersey Department of Transportation Standard Construction
Details, as amended:
(1)
Headwalls and riprap.
(2)
A chain-link fence, four feet high, around the entire perimeter may
be required by the Planning Board. In cases where a fence is required,
a twelve-foot opening shall be provided for vehicular access to streets
by means of a fifteen-foot-wide access right-of-way. The fence shall
not extend into the building front yard setback area.
(3)
An eighteen-inch berm around the inside of the basin.
(4)
Landscaping is required around the entire perimeter, except where
it faces planned open spaces or wooded areas or other natural or man-made
visual separation existing between the facility and adjoining lands.
Any person(s) who continues to be in violation of the provisions
of this article, after being duly notified, shall be subject to a
fine not to exceed $5,000 plus costs of remediation.
This chapter shall take effect immediately upon the approval
by the county review agency or 60 days from the receipt of the ordinance
by the county review agency if the county review agency should fail
to act.
If the provisions of any section, subsection, paragraph, subdivision,
or clause of this chapter 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 chapter.
