[HISTORY: Adopted by the Borough Council of the Borough of
Wrightstown as indicated in article histories. Amendments noted where
applicable.]
[Adopted 12-27-2007 by Ord. No. 2007-08]
A.
Purpose.
(1)
It is hereby determined that:
(a)
Land development projects and associated disturbance of vegetation
and soil and changes in land cover, including increases in impervious
cover, alter the hydrologic response of local watersheds and increase
stormwater runoff rates and volumes. If inadequately or improperly
managed, this stormwater runoff can deplete groundwater resources
and increase flooding, stream channel erosion, and sediment transport
and deposition.
(b)
This stormwater runoff contributes to increased quantities of
waterborne pollutants.
(c)
Increases of stormwater runoff, soil erosion and nonpoint source
pollutants have occurred in the past as a result of land development
and contribute to the degradation of the water resources of Borough
of Wrightstown.
(d)
Certain lands of Borough of Wrightstown lie within the Pinelands
Area, and therefore, development in this portion of Borough of Wrightstown
is subject to the requirements of the Pinelands Protection Act (N.J.S.A.
13:18A-1 et seq.) and the implementing regulations and minimum standards
contained in the Pinelands Comprehensive Management Plan (CMP) (N.J.A.C.
7:50-1.1 et seq.). The purpose and intent of these regulations and
standards is to promote orderly development of the Pinelands so as
to preserve and protect the significant and unique natural, ecological,
agricultural, archaeological, historical, scenic, cultural and recreational
resources of the Pinelands.
(e)
Pinelands Area resources are to be protected in accordance with
Pinelands Comprehensive Management Plan at N.J.A.C. 7:50 et seq.,
New Jersey's Stormwater Management Rules at N.J.A.C. 7:8-1.1
et seq. and New Jersey's surface water quality antidegradation
policies contained in the New Jersey Surface Water Quality Standards
at N.J.A.C. 7:9B-1.1 et seq. Permitted uses shall maintain the ecological
character and quality of the Pinelands, including good water quality
and natural rates and volumes of flow.
(f)
Increased stormwater rates and volumes and the sediments and
pollutants associated with stormwater runoff from future development
projects within the Pinelands Area have the potential to adversely
affect the Borough of Wrightstown's streams and water resources
and the streams and water resources of downstream municipalities.
(g)
Stormwater runoff, soil erosion and nonpoint source pollution
can be controlled and minimized through the regulation of stormwater
runoff from development sites.
(h)
It is in the public interest to regulate the discharge of stormwater runoff from "major development" projects, as defined in § 184-7 of this article, conducted within the Pinelands Area, as provided in this article, in order to control and minimize increases in stormwater runoff rates and volumes, to maintain groundwater recharge, and to control and minimize soil erosion, stream channel erosion and nonpoint source pollution associated with stormwater runoff.
(2)
Therefore, it is the purpose of this article to establish minimum
stormwater management requirements and controls for major development,
consistent with the statewide stormwater requirements at N.J.A.C.
7:8, the regulations and standards contained in the Pinelands CMP,
and the provisions of the adopted Master Plan and land use ordinances
of Borough of Wrightstown.
B.
Goals and techniques.
(1)
Through this article, the Borough of Wrightstown has established
the following goals for stormwater control:
(a)
To reduce flood damage, including damage to life and property;
(b)
To minimize any increase in stormwater runoff from new development;
(c)
To reduce soil erosion from any development or construction
project;
(d)
To assure the adequacy of existing and proposed culverts and
bridges and other in-stream structures;
(e)
To maintain groundwater recharge;
(f)
To minimize any increase in nonpoint pollution;
(g)
To maintain the integrity of stream channels for their biological
functions, as well as for drainage;
(h)
To restore, protect, maintain and enhance the quality of the
streams and water resources of the Borough of Wrightstown and the
ecological character and quality of the Pinelands Area;
(i)
To minimize pollutants in stormwater runoff from new and existing
development in order to restore, protect, enhance and maintain the
chemical, physical and biological integrity of the surface waters
and groundwaters of the Borough of Wrightstown, to protect public
health and to enhance the domestic, municipal, recreational, industrial
and other uses of water; and
(j)
To protect public safety through the proper design and operation
of stormwater management basins.
(2)
In order to achieve the goals for stormwater control set forth in
this article, the Borough of Wrightstown has identified the following
management techniques:
(a)
Implementation of multiple stormwater management best management
practices (BMPs) may be necessary to achieve the performance standards
for stormwater runoff quantity and rate, groundwater recharge, erosion
control, and stormwater runoff quality established through this article.
(b)
Compliance with the stormwater runoff quantity and rate, groundwater
recharge, erosion control, and stormwater runoff quality standards
established through N.J.A.C. 7:8-1.1 et seq., and this article, shall
be accomplished to the maximum extent practicable through the use
of nonstructural BMPs before relying on structural BMPs. Nonstructural
BMPs are also known as low-impact development (LID) techniques.
(c)
Nonstructural BMPs shall include both environmentally sensitive
site design and source controls that prevent pollutants from being
placed on the site or from being exposed to stormwater.
(d)
Source control plans shall be developed based upon physical
site conditions and the origin, nature and the anticipated quantity
or amount of potential pollutants.
(e)
Structural BMPs, where necessary, shall be integrated with nonstructural
stormwater management strategies and proper maintenance plans.
(f)
When using structural BMPs, multiple stormwater management measures,
smaller in size and distributed spatially throughout the land development
site, shall be used wherever possible to achieve the performance standards
for water quality, quantity and groundwater recharge established through
this article before relying on a single, larger stormwater management
measure to achieve these performance standards.
C.
Applicability. This article shall apply to:
(1)
All site plans and subdivisions for major developments occurring
within the Pinelands Area that require preliminary or final site plan
or subdivision review; and
(2)
All major development projects undertaken by the Borough of Wrightstown
shall comply with this article. (Note: This clause is intended to
provide consistency with DEP's stormwater management requirements.
As per normal practice, all development within the Pinelands Area
which is undertaken by a Pinelands Area municipality shall comply
with all of the requirements of the CMP.)
D.
Procedures. In addition to other development review procedures set forth in the Code of the Borough of Wrightstown, major developments located within the Pinelands Area shall comply with the stormwater management requirements and specifications set forth in this article. New agricultural development that meets the definition of "major development" in § 184-7 of this article shall be submitted to the appropriate Soil Conservation District for review and approval in accordance with the requirements of N.J.A.C. 7:8-5.4(b).
E.
Compatibility with other permit and ordinance requirements.
(1)
Development approvals issued for subdivisions and site plans pursuant
to this article 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
ordinance, code, rule, regulation, statute, act or other provision
of law. The stormwater management requirements within this article,
as they relate to major development, supersede other design requirements
stipulated in the Borough Code, including but not limited to the following
section(s):
(2)
In their interpretation and application, the provisions of this article
shall be held to be the minimum requirements for the promotion of
the public health, safety, and general welfare. This article 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 article imposes restrictions different
from those imposed by any other ordinance, rule or regulation, or
other provision of law, the more restrictive or stringent provisions
or higher standards shall control.
(3)
In the event that a regional stormwater management plan(s) is prepared
and formally adopted pursuant to N.J.A.C. 7:8-1.1 et seq. for any
drainage area(s) or watershed(s) of which the Borough of Wrightstown
is a part, the stormwater provisions of such a plan(s) shall be adopted
by Borough of Wrightstown within one year of the adoption of a regional
stormwater management plan (RSWMP) as an amendment to an areawide
water quality management plan. Local ordinances proposed to implement
the RSWMP shall be submitted to the Commission for certification within
six months of the adoption of the RSWMP per N.J.A.C. 7:8 and the Pinelands
CMP (N.J.A.C. 7:50.)
A.
Submission of site development stormwater plan.
(1)
Whenever an applicant seeks municipal approval of a site development that is subject to this article, the applicant shall submit all of the required components of the checklist for the site development stormwater plan at Subsection C below as part of the applicant's application for subdivision or site plan approval. These required components are in addition to any other information required under any provisions of the Borough of Wrightstown's Land Use Ordinance or by the Pinelands Commission pursuant to N.J.A.C. 7:50-1.1 et seq.
(2)
The applicant shall demonstrate that the site development project
meets the standards set forth in this article.
B.
Site development stormwater plan approval. The applicant's site
development stormwater plan shall be reviewed as a part of the subdivision
or site plan review process by the municipal board or official from
which municipal approval is sought. That municipal board or official
shall consult the engineer retained by the Planning Board and/or Zoning
Board (as appropriate) to determine if all of the checklist requirements
have been satisfied and to determine if the project meets the standards
set forth in this article.
C.
Checklist requirements. Any application for approval of a major development
shall include at least the following information. All required engineering
plans shall be submitted to the Borough of Wrightstown and the Pinelands
Commission in CAD Format 15 or higher, registered and rectified to
NJ State Plane Feet NAD 83 or Shape Format NJ State Plan Feet NAD
83, and all other documents shall be submitted in both paper and commonly
used electronic file formats such as PDF, word processing, database
or spreadsheet files. Three copies of each item shall be submitted.
(1)
Topographic base map. The applicant shall submit a topographic base
map of the site which extends a minimum of 300 feet beyond the limits
of the proposed development, at a scale of one inch equals 200 feet
or greater, showing one-foot contour intervals. The map shall indicate
the following: existing surface water drainage, shorelines, steep
slopes, soils, highly erodible soils, perennial or intermittent streams
that drain into or upstream of any Category One or Pinelands waters,
wetlands and floodplains along with their appropriate buffer strips,
marshlands and other wetlands, pervious or vegetative surfaces, existing
surface and subsurface human-made structures, roads, bearing and distances
of property lines, and significant natural and man-made features not
otherwise shown. The Borough of Wrightstown or the Pinelands Commission
may require upstream tributary drainage system information as necessary.
(2)
Environmental site analysis. The applicant shall submit a written
description along with the drawings of the natural and human-made
features of the site and its environs. This description should include:
(a)
A discussion of environmentally critical areas, 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 for or
constraints on development; and
(b)
Detailed soil and other environmental conditions on the portion
of the site proposed for installation of any stormwater BMPs, including,
at a minimum, soils report based on on-site soil tests; locations
and spot elevations in plan view of test pits and permeability tests;
permeability test data and calculations; and any other required soil
data (e.g., mounding analyses results) correlated with location and
elevation of each test site; cross section of proposed stormwater
BMP with side-by-side depiction of soil profile drawn to scale and
seasonal high water table elevation identified; and any other information
necessary to demonstrate the suitability of the specific proposed
structural and nonstructural stormwater management measures relative
to the environmental conditions on the portion(s) of the site proposed
for implementation of those measures.
(3)
Project description and site plan(s). The applicant shall submit
a map (or maps) at the scale of the topographic base map indicating
the location of existing and proposed buildings, roads, parking areas,
utilities, structural facilities for stormwater management and sediment
control, and other permanent structures. The map(s) shall also clearly
show areas where alterations will occur in the natural terrain and
cover, including lawns and other landscaping, and seasonal high groundwater
elevations. A written description of the site plan and justification
for proposed changes in natural conditions shall also be provided.
(4)
Land use planning and source control plan.
(a)
The applicant shall submit a detailed land use planning and source control plan which provides a description of how the site will be developed to meet the erosion control, groundwater recharge and stormwater runoff quantity and quality standards at § 183-4 through use of nonstructural or low-impact development techniques and source controls to the maximum extent practicable before relying on structural BMPs. The land use planning and source control plan shall include a detailed narrative and associated illustrative maps and/or plans that specifically address how each of the following nine nonstructural strategies identified in Subchapter 5 of the NJDEP Stormwater Management Rules (N.J.A.C. 7:8-5) and set forth below (Subsection C(4)(a)[1] through [9]) will be implemented to the maximum extent practicable to meet the standards at § 184-4 of this article on the site. If one or more of the nine nonstructural strategies will not be implemented on the site, the applicant shall provide a detailed rationale establishing a basis for the contention that use of the strategy is not practicable on the site.
[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 pre-development "time of concentration";
[5]
Minimize land disturbance, including clearing and grading;
[6]
Minimize soil compaction and all other soil disturbance;
[7]
Provide low-maintenance landscaping that provides for the retention
and planting of native plants and minimizes the use of lawns, fertilizers
and pesticides, in accordance with N.J.A.C. 7:50-6.24;
[8]
Provide vegetated open-channel conveyance systems discharging
into and through stable vegetated areas; and
[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. These source
controls shall 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]
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, when establishing vegetation after
land disturbance.
(b)
For sites where stormwater will be generated from high pollutant loading areas or where stormwater will be exposed to source material, as defined in § 184-7 of this article, the applicant shall also demonstrate in the land use planning and source control plan that the requirements of § 184-4 have been met.
(c)
The use of nonstructural strategies to meet the performance standards in § 184-4 of this article is not required for development sites creating less than one acre of disturbance. However, each application for major development and any other application where the Borough of Wrightstown otherwise requires a landscaping plan shall contain a landscaping or revegetation plan in accordance with the CMP standards at N.J.A.C. 7:50-6.24(c). In addition, the applicant shall demonstrate that, at a minimum, existing trees and vegetation on the development site will be preserved and protected according to the minimum standards established by provisions of the Borough of Wrightstown Land Use Ordinance or the Zoning Ordinance[1] or by conditions of zoning or variance approval.
(5)
Stormwater management facilities map. The applicant shall submit
a map, at the same scale as the topographic base map, depicting the
following information:
(a)
The total area to be disturbed, paved and/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 manage and dispose of stormwater; and
(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 (if applicable)
and emergency spillway provisions with maximum discharge capacity
of each spillway.
(6)
Calculations (groundwater recharge and stormwater runoff rate, volume and quality). The applicant shall submit comprehensive hydrologic and hydraulic design calculations for the pre-development and post-development conditions for the design storms specified in § 184-3. The standards for groundwater recharge and stormwater runoff rate, volume and quality required by § 184-4 shall be met using the methods, calculations and assumptions provided in § 184-3.
(7)
Inspection, maintenance and repair plan. The applicant shall submit a detailed plan describing how the proposed stormwater management measure(s) shall meet the maintenance and repair requirements of § 184-6 of this article. Said plan shall include, at a minimum, the following elements:
(a)
The frequency with which inspections will be made;
(b)
The specific maintenance tasks and requirements for each proposed
structural and nonstructural BMP;
(c)
The name, address and telephone number for the entity responsible
for implementation of the maintenance plan;
(d)
The reporting requirements; and
(e)
Copies of the inspection and maintenance reporting sheets.
(8)
Exception from submission requirements. An exception may be granted from submission of any of these required components [except Subsection C(7), above, Inspection, maintenance, and repair plan] if its absence will not materially affect the review process. However, items required pursuant to the application requirements of the Wrightstown Borough Code of Ordinances, Chapter 219, Article IV, § 219-20, shall be submitted to the New Jersey Pinelands Commission unless the Executive Director waives or modifies the application requirements.
A.
Method of calculating stormwater runoff rate and volume.
(1)
In complying with the stormwater runoff quantity and rate standards in § 184-4B, 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. Alternative methods of calculation may be utilized, provided that such alternative methods are at least as protective as the NRCS methodology when considered on a regional stormwater management basis.
(2)
In calculating stormwater runoff using the NRCS methodology, the
design engineer shall separately calculate and then combine the runoff
volumes from pervious and directly connected impervious surfaces within
each drainage area within the parcel.
(3)
Calculation of stormwater runoff from unconnected impervious surfaces
shall be based, as applicable, upon the Two-Step Method described
in the current New Jersey Stormwater Best Management Practices Manual
or the NRCS methodology.
(4)
In calculating stormwater runoff using the NRCS methodology, the
design engineer shall use appropriate 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.
(5)
When calculating stormwater runoff for pre-developed site conditions,
the design engineer shall use the following criteria:
(a)
When selecting or calculating runoff curve numbers (CNs) for
pre-developed project site conditions, the project site's land
cover shall be assumed to be woods in good condition. 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 has 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.
(c)
All pre-developed land covers shall be assumed to be in good
hydrologic condition and, if cultivated, shall be assumed to have
conservation treatment.
(d)
In calculating pre-developed site stormwater runoff, the design
engineer shall include the effects of all land features and structures,
such as ponds, wetlands, depressions, hedgerows, and culverts, that
affect pre-developed site stormwater runoff rates and/or volumes.
(e)
Where tailwater will affect the hydraulic performance of a stormwater
management measure, the design engineer shall include such effects
in the measure's design.
B.
Method of calculating stormwater runoff quality.
(1)
In complying with the stormwater runoff quality standards in § 184-4F(1), 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 1.25 inches of rainfall falling in a nonlinear pattern
in two hours. Details of the water quality design storm are shown
in Table 1.
(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)
|
Time
(minutes)
|
Cumulative Rainfall
(inches)
| |
|
0
|
0.0000
|
65
|
0.8917
| |
|
5
|
0.0083
|
70
|
0.9917
| |
|
10
|
0.0166
|
75
|
1.0500
| |
|
15
|
0.0250
|
80
|
1.0840
| |
|
20
|
0.0500
|
85
|
1.1170
| |
|
25
|
0.0750
|
90
|
1.1500
| |
|
30
|
0.1000
|
95
|
1.1750
| |
|
35
|
0.1330
|
100
|
1.2000
| |
|
40
|
0.1660
|
105
|
1.2250
| |
|
45
|
0.2000
|
110
|
1.2334
| |
|
50
|
0.2583
|
115
|
1.2417
| |
|
55
|
0.3583
|
120
|
1.2500
| |
|
60
|
0.6250
| |||
|
Source: N.J.A.C. 7:8-5.5(a).
|
(4)
Total suspended solids (TSS) reduction calculations.
(a)
If more than one stormwater BMP in series is necessary to achieve
the required eighty-percent 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; and
| |
|
B
|
=
|
The TSS percent removal rate applicable to the second BMP.
| |
(b)
If there is more than one on-site drainage area, the eighty-percent
TSS removal rate shall apply to each drainage area, unless the runoffs
from the subareas converge on site, in which case the removal rate
can be demonstrated through a calculation using a weighted average.
(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 § 184-11A 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 Borough of Wrightstown. Any alternative stormwater
management measure, removal rate or method of calculating the removal
rate shall be subject to approval by Borough of Wrightstown, and a
copy shall be provided to the following:
[1]
The Division of Watershed Management, New Jersey Department
of Environmental Protection, P.O. Box 418, Trenton, NJ 08625-0418;
and
[2]
The New Jersey Pinelands Commission, P.O. Box 7, New Lisbon,
NJ 08064.
|
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% to 60% (Final rate based upon detention time; see the New
Jersey BMP Manual, Chapter 9.)
|
20%
|
20%
|
|
Infiltration basin
|
80%
|
60%
|
50%
|
|
Manufactured treatment device
|
Pollutant removal rates as certified by NJDEP; see § 184-3.
|
Pollutant removal rates as certified by NJDEP; see § 184-3.
|
Pollutant removal rates as certified by NJDEP; see § 184-3.
|
|
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% to 90% (Final rate based upon pool volume and detention
time; see the New Jersey 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 post-development 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 § 184-4F.
C.
Methods of calculating groundwater recharge. In complying with the groundwater recharge requirements in § 184-4C(1)(a), the design engineer may 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 § 184-11A or from the New Jersey BMP Manual.
(1)
Alternative groundwater recharge calculation methods to meet these
requirements may be used upon approval by the Municipal Engineer.
(2)
In complying with the groundwater recharge requirements in § 184-4C(1)(b), 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.
(3)
When calculating groundwater recharge or stormwater runoff for pre-developed
site conditions, the design engineer shall use the following criteria:
(a)
When selecting land covers or calculating runoff curve numbers
(CNs) for pre-developed 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 pre-developed 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.
(1)
To the maximum extent practicable, the performance standards in § 184-4 for major development shall be met by incorporating the nine nonstructural strategies identified in Subchapter 5 of the New Jersey Stormwater Management Rules (N.J.A.C. 7:8-5), and set forth in § 184-2C(4)(a), into the design. The applicant shall identify within the land use planning and source control plan required by § 184-2C(4) of this article how each of the nine nonstructural measures will be incorporated into the design of the project to the maximum extent practicable.
(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 § 184-2, to the Borough of Wrightstown. A determination by the Borough of Wrightstown 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 Borough of Wrightstown;
(b)
The land use planning and source control plan is amended to provide an alternative nonstructural strategy or measure that is not included in the list of nine nonstructural measures, but still meets the performance standards in § 184-4, and the amended plan is approved by the Borough of Wrightstown; or
(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 Borough of Wrightstown.
(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
Borough of Wrightstown Land Use Ordinance, Zoning Ordinance[1] 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)
In addition to all other requirements of this section, each application
for major development, and any other application where the Borough
of Wrightstown otherwise requires a landscaping plan, shall contain
a landscaping or revegetation plan in accordance with the Pinelands
CMP standards at N.J.A.C. 7:50-6.24(c).
(5)
Any land area used as a nonstructural stormwater management measure to meet the performance standards in § 184-4 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 Borough of Wrightstown that ensures that that measure, or equivalent stormwater management measure, is maintained in perpetuity, as detailed in § 184-6 of this article.
(6)
Guidance for nonstructural stormwater management strategies is available in the New Jersey BMP Manual, which may be obtained from the address identified in § 184-12A or found on the NJDEP's website at www.njstormwater.org.
(7)
Exception for major development sites creating less than one acre of disturbance. The use of nonstructural strategies to meet the performance standards in § 184-4 of this article is not required for major development creating less than one acre of disturbance. However, the following requirements shall be met:
(a)
Each application for major development and any other application
where the Borough of Wrightstown otherwise requires a landscaping
plan shall contain a landscaping or revegetation plan prepared in
accordance with the Pinelands CMP standards [N.J.A.C. 7:50-6.24(c)];
(b)
Each applicant shall demonstrate that, at a minimum, existing
trees and vegetation on the development site will be preserved and
protected according to the minimum standards established by provisions
of the Borough of Wrightstown Land Use Ordinance, Zoning Ordinance[2] or by conditions of zoning or variance approval; and
(c)
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.
B.
Stormwater runoff quantity and rate standards.
(1)
There shall be no direct discharge of stormwater runoff from any
point or nonpoint source to any wetland, wetlands transition area
or surface water body (all outfall structures and their components,
including associated clearing and land disturbance, must be located
outside any wetland, wetlands transition area or surface water body).
In addition, stormwater runoff shall not be directed in such a way
as to increase the volume and/or rate of discharge into any surface
water body from that which existed prior to development of the site.
To the maximum extent practical, there shall be no direct discharge
of stormwater runoff onto farm fields so as to protect farm crops
from damage due to flooding and long-term saturation of cultivated
crops and cropland.
(2)
For all major developments, the total runoff volume generated from
the net increase in impervious surfaces by a ten-year, twenty-four-hour
storm shall be retained and infiltrated on site.
(3)
In addition, the design engineer, using the assumptions and factors for stormwater runoff and groundwater recharge calculations contained in § 184-3, shall either:
(a)
Demonstrate through hydrologic and hydraulic analysis that the
post-developed stormwater runoff hydrographs from the project site
for the two-, ten-, and one-hundred-year storms do not exceed, at
any point in time, the site's pre-developed runoff hydrographs
for the same storms;
(b)
Demonstrate through hydrologic and hydraulic analysis that under
post-developed site conditions:
[1]
There is no increase in pre-developed stormwater runoff rates
from the project site for the two-, ten-, and one-hundred-year storms;
and
[2]
Any increased stormwater runoff volume or change in stormwater
runoff timing for the two-, ten-, and one-hundred-year storms will
not increase flood damage at or downstream of the project site. When
performing this analysis for pre-developed site conditions, all off-site
development levels shall reflect existing conditions. When performing
this analysis for post-developed site conditions, all off-site development
levels shall reflect full development in accordance with current zoning
and land use ordinances; or
(c)
Demonstrate that the peak post-developed stormwater runoff rates
from the project site for the two-, ten-, and one-hundred-year storms
are 50%, 75% and 80%, respectively, of the site's peak pre-developed
stormwater runoff rates for the same storms. Peak outflow rates from
on-site stormwater measures for these storms shall be adjusted where
necessary to account for the discharge of increased stormwater runoff
rates and/or volumes from project site areas not controlled by the
on-site measures. These percentages do not have to be applied to those
portions of the project site that are not proposed for development
at the time of application, provided that such areas are:
C.
Groundwater recharge standards.
(1)
For all major developments, with the exception of those described in § 184-4C(4), below, the design engineer, using the assumptions and factors for stormwater runoff and groundwater recharge calculations contained in § 184-3, shall either:
(a)
Demonstrate through hydrologic and hydraulic analysis that the
post-developed project site maintains 100% of the site's pre-developed
average annual groundwater recharge volume; or
(b)
Demonstrate through hydrologic and hydraulic analysis that any
increase in the project site's stormwater runoff volume for the
two-year, twenty-four-hour storm from pre-developed to post-developed
conditions is infiltrated on site.
(2)
The design engineer shall assess the hydraulic impact on the groundwater
table and design the project site and all site groundwater recharge
measures so as to avoid adverse hydraulic impacts. Adverse hydraulic
impacts include, but are not limited to, raising the groundwater table
so as to cause surface ponding; flooding of basements and other subsurface
structures and areas; preventing a stormwater infiltration basin from
completely draining via infiltration within 72 hours of a design storm
event; and interference with the proper operation of subsurface sewage
disposal systems and other surface and subsurface facilities in the
vicinity of the groundwater recharge measure.
(3)
The standards for groundwater recharge required by this section shall be met using the methods, calculations and assumptions provided in § 184-3.
(4)
Exceptions. The preceding groundwater recharge standards shall not
apply to sites that create less than one acre of disturbance.
D.
Erosion control standards. 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 its implementing
regulations, N.J.A.C. 2:90-1.1 through 2:90-1.4.
E.
Stormwater runoff quality standards.
(1)
There shall be no direct discharge of stormwater runoff from any
point or nonpoint source to any wetland, wetlands transition area
or surface water body (all outfall structures and their components
including associated clearing and land disturbance must be located
outside any wetland, wetlands transition area or surface water body).
(2)
Stormwater management measures shall be designed to reduce the total
suspended solids (TSS) load in the stormwater runoff from the post-developed
site by 80% expressed as an annual average.
(3)
Stormwater management measures shall also be designed to reduce the
nutrient load in the stormwater runoff from the post-developed site
by the maximum extent practicable. In achieving this reduction, the
design of the development site shall include nonstructural and structural
stormwater management measures that optimize nutrient removal while
still achieving the groundwater recharge, runoff quantity and rate,
and TSS removal standards in this section.
(4)
The standards for stormwater runoff quality required by this section shall be met using the methods, calculations, assumptions and pollutant removal rates provided in § 184-3.
(5)
Exceptions.
F.
Additional stormwater quality standards for high pollutant loading
areas and areas where stormwater runoff is exposed to source material.
(2)
For a major development in areas described in Subsection F(1)(a) or (b) above, in addition to the infiltration requirements specified in § 184-4B(2) and the groundwater recharge requirements specified in § 184-4C, the applicant shall demonstrate in the land use planning and source control plan required in § 184-2C(4) that the following requirements have been met:
(b)
The stormwater runoff from the areas described in Subsection F(1)(a) and (b) above is segregated to the maximum extent practicable from the stormwater runoff generated from the remainder of the site such that co-mingling of the stormwater runoff from the areas described in Subsection F(1)(a) and (b) above and the remainder of the site will be minimized;
(d)
The stormwater runoff from or co-mingled with the areas described in Subsection F(1)(a) and (b) above for the water quality design storm, defined in § 184-3B, Table 1, shall be subject to pretreatment by one or more of the following stormwater BMPs, designed in accordance with the New Jersey BMP Manual to provide ninety-percent TSS removal:
[1]
Bioretention system;
[2]
Sand filter;
[3]
Wet pods which shall be hydraulically disconnected by a minimum
of two feet of vertical separation from the seasonal high water table
and shall be designed to achieve a minimum eighty-percent TSS removal
rate;
[4]
Constructed stormwater wetlands; and/or
[5]
Media filtration system manufactured treatment device with a
minimum eighty-percent TSS removal as verified by the New Jersey Corporation
for Advanced Technology and as certified by NJDEP.
(e)
If the potential for contamination of stormwater runoff by petroleum products exists on site, prior to being conveyed to the pretreatment BMP required in § 184-4F(2)(d) above, the stormwater runoff from the areas described in Subsection F(1)(a) and (b) above shall be conveyed through an oil/grease separator or other equivalent manufactured filtering device to remove the petroleum hydrocarbons. The applicant shall provide the reviewing agency with sufficient data to demonstrate acceptable performance of the device.
G.
Threatened and endangered species and associated habitat standards.
Stormwater measures shall address the impacts of the development on
habitat for threatened and endangered species in accordance with N.J.A.C.
7:8-5.2(c), N.J.A.C. 7:50-6.27 and N.J.A.C. 7:50-6.33 and 7:50-6.34.
H.
Exceptions and mitigation requirements.
(1)
Exceptions from strict compliance from the groundwater recharge,
stormwater runoff quantity, and stormwater runoff quality requirements
established by this article may be granted, at the discretion of the
Borough of Wrightstown, and subject to approval by the Pinelands Commission,
provided that all of the following conditions are met:
(a)
The exception is consistent with that allowed by the Borough
of Wrightstown.
(b)
The Borough of Wrightstown has an adopted and effective municipal
stormwater management plan in accordance with N.J.A.C. 7:8-4.4, which
includes a mitigation plan in accordance with N.J.A.C. 7:8-4.2(c)11,
and is also certified by the Pinelands Commission. The mitigation
plan shall identify what measures are necessary to offset the deficit
created by granting the exception, and the municipality shall submit
a written report to the county review agency and the NJDEP describing
the exception and the required mitigation. Guidance for developing
municipal stormwater management plans, including mitigation plans,
is available from the NJDEP, Division of Watershed Management and
the New Jersey BMP Manual.
(c)
The applicant demonstrates that mitigation, in addition to the requirements of a mitigation plan discussed in Subsection H(1)(b) above, will be provided consistent with one of the following options:
[1]
Mitigation may be provided off site, but within the Pinelands
Area and within the same drainage area as the development site, and
shall meet or exceed the equivalent recharge, quality or quantity
performance standard which is lacking on the development site due
to the exception; or
[2]
In lieu of the required mitigation, a monetary "in-lieu contribution"
may be provided by the applicant to the Borough of Wrightstown in
accordance with the following:
[a]
The amount of the in-lieu contribution shall be determined by
the Borough of Wrightstown, but the maximum in-lieu contribution required
shall be equivalent to the cost of implementing and maintaining the
stormwater management measure(s) for which the exception is granted.
[b]
The in-lieu contribution shall be used to fund an off-site stormwater control mitigation project(s) located within the Pinelands Area, within the same drainage area as the development site, and shall meet or exceed the equivalent recharge, quality or quantity performance standards which are lacking on the development site. Such mitigation project shall be identified by the Borough of Wrightstown in the Borough of Wrightstown's adopted municipal stormwater management plan. The stormwater control project to which the monetary contribution will be applied shall be identified by the Borough of Wrightstown at the time the exception is granted. The applicant shall amend the project description and site plan required in § 184-2C(3) to incorporate a description of both the standards for which an on-site exception is being granted and of the selected off-site mitigation project.
[c]
The Borough of Wrightstown shall expend the in-lieu contribution to implement the selected off-site mitigation project within five years from the date that payment is received. Should the Borough of Wrightstown fail to expend the in-lieu contribution within the required time frame, the mitigation option provided in § 184-4H(1)(c)[2] of this article shall be void, and the Borough of Wrightstown shall be prohibited from collecting in-lieu contributions.
(2)
An exception from strict compliance granted in accordance with Subsection H(1) above shall not constitute a waiver of strict compliance from the requirements of the Pinelands Comprehensive Management Plan at N.J.A.C. 7:50. An applicant should contact the Pinelands Commission to determine whether a waiver of strict compliance is also required in accordance with N.J.A.C. 7:50, Subchapter 4, Part V.
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 major land development
in the Pinelands, provided that the applicant demonstrates that they
are designed, constructed and maintained so as to meet the standards
and requirements established by this article. If alternative stormwater
management measures are proposed, the applicant shall demonstrate
that the selected measures will achieve the standards established
by this article.
(a)
Bioretention systems;
(b)
Constructed stormwater wetlands;
(c)
Extended detention basins;
(d)
Infiltration basins;
(e)
Vegetated filter strips;
(f)
Infiltration basins and trenches;
(g)
Wet ponds with suitable liners;
(h)
Pervious paving systems; and
(i)
Manufactured treatment devices, provided that 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 § 184-6 of this article.
(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 Municipal 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:
(a)
Use of natural, nonwetland wooded depressions for stormwater
runoff storage; and
(b)
Establishment of attractive landscaping in and around the basin
that mimics the existing vegetation and incorporates native Pinelands
plants, including, but not limited to, the species listed in N.J.A.C.
7:50-6.25 and 6.26.
(8)
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).
(9)
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 Municipal Engineer.
(10)
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
Municipal Engineer. Based upon the Municipal Engineer's review
of the as-built plans, all corrections or remedial actions deemed
by the Municipal Engineer to be necessary due to the failure to comply
with the standards established by this article and/or any reasons
of public health or safety shall be completed by the applicant. In
lieu of review by the Municipal Engineer, the Borough of Wrightstown
reserves the right to engage a professional engineer to review the
as-built plans. The applicant shall pay all costs associated with
such review.
B.
Design and construction standards for stormwater infiltration BMPs.
(1)
Stormwater infiltration BMPs, such as bioretention systems with infiltration,
dry wells, infiltration basins, pervious paving systems with storage
beds, and sand filters with infiltration, shall be designed, constructed
and maintained to completely drain the total runoff volume generated
by the basin's maximum design storm within 72 hours after a storm
event. Runoff storage for greater times can render the BMP ineffective
and may result in anaerobic conditions, odor and both water quality
and mosquito breeding problems.
(2)
Stormwater infiltration BMPs shall be designed, constructed and maintained
to provide a minimum separation of at least two feet between the elevation
of the lowest point of the bottom of the infiltration BMP and the
seasonal high water table.
(3)
A stormwater infiltration BMP shall be sited in suitable soils verified
by field testing to have permeability rates between one inch and 20
inches per hour. If such site soils do not exist or if the design
engineer demonstrates that it is not practical for engineering, environmental
or safety reasons to site the stormwater infiltration BMP(s) in such
soils, then the stormwater infiltration BMP(s) may be sited in soils
verified by field testing to have permeability rates in excess of
20 inches per hour, provided that a bioretention system, designed,
installed and maintained in accordance with the New Jersey BMP Manual,
is installed to meet one of the following conditions:
(a)
The bioretention system is constructed as a separate measure
designed to provide pretreatment of stormwater and to convey the pretreated
stormwater into the infiltration BMP; or
(b)
The bioretention system is integrated into and made part of
the infiltration BMP and, as such, does not require an underdrain
system. If this option is selected, the infiltration BMP shall be
designed and constructed so that the maximum water depth in the bioretention
system portion of the BMP during treatment of the stormwater quality
design storm is 12 inches in accordance with the New Jersey BMP Manual.
(4)
The minimum design permeability rate for the soil within a BMP that relies on infiltration shall be 0.5 inch per hour. A factor of safety of two shall be applied to the soil's field-tested permeability rate to determine the soil's design permeability rate. For example, if the field-tested permeability rate of the soil is four inches per hour, its design permeability rate would be two inches per hour. The minimum design permeability rate for the soil within a stormwater infiltration basin shall also be sufficient to achieve the minimum seventy-two-hour drain time described in Subsection B(1) above. The maximum design permeability shall be 10 inches per hour.
(5)
A soil's field-tested permeability rate shall be determined
in accordance with the following:
(a)
The pre-development field test permeability rate shall be determined according to the methodologies provided in § 184-11C(3) of this article;
(b)
The results of the required field permeability tests shall demonstrate
a minimum tested infiltration rate of one inch per hour;
(c)
After all construction activities have been completed on the site and the finished grade has been established in the infiltration BMP, post-development field permeability tests shall also be conducted according to the methodologies provided in § 184-11C(3) of this article;
(d)
If the results of the post-development field permeability tests fail to achieve the minimum required design permeability rates in Subsection B(5) above utilizing a factor of safety of two, the stormwater infiltration BMP shall be renovated and retested until such minimum required design permeability rates are achieved; and
(e)
The results of all field permeability tests shall be certified
by a professional engineer and transmitted to the Municipal Engineer.
(6)
To help ensure maintenance of the design permeability rate over time,
a six-inch layer of K5 soil shall be placed on the bottom of a stormwater
infiltration BMP. This soil layer shall meet the textural and permeability
specifications of a K5 soil as provided at N.J.A.C. 7:9A, Appendix
A, Figure 6, and be certified to meet these specifications by a professional
engineer licensed in the State of New Jersey. The depth to the seasonal
high water table shall be measured from the bottom of the K5 sand
layer.
(7)
The design engineer shall assess the hydraulic impact on the groundwater
table and design the project site and all stormwater infiltration
basins so as to avoid adverse hydraulic impacts. Adverse hydraulic
impacts include, but are not limited to, raising the groundwater table
so as to cause surface ponding; the flooding of basements and other
subsurface structures and areas; preventing a stormwater infiltration
basin from completely draining via infiltration within 72 hours of
a design storm event; and interference with the proper operation of
subsurface sewage disposal systems and other surface and subsurface
structures in the vicinity of the stormwater infiltration basin.
(8)
The design engineer shall conduct a mounding analysis, as defined in § 184-7,[1] of all stormwater infiltration BMPs. The mounding analysis shall be conducted in accordance with the requirements in § Section 184-11C(3). Where the mounding analysis identifies adverse impacts, the stormwater infiltration BMP shall be redesigned or relocated, as appropriate.
(9)
Stormwater infiltration BMPs shall be constructed in accordance with
the following:
(a)
To avoid sedimentation that may result in clogging and reduce
the basin's permeability rate, stormwater infiltration basins
shall be constructed according to the following:
[1]
Unless the conditions in Subsection B(9)(a)[2] below are met, a stormwater infiltration basin shall not be placed into operation until its drainage area is completely stabilized. Instead, upstream runoff shall be diverted around the basin and into separate, temporary stormwater management facilities and sediment basins. Such temporary facilities and basins shall be installed and utilized for stormwater management and sediment control until stabilization is achieved in accordance with the Standards for Soil Erosion and Sediment Control in New Jersey,[2] which is incorporated herein by reference as amended and
supplemented.
[2]
Editor's Note: Said standards are available from all State Soil Conservation Districts. See § 184-12B(2).
[2]
If the design engineer determines that, for engineering, environmental or safety reasons, temporary stormwater management facilities and sediment basins cannot be constructed on the site, the stormwater infiltration basin may be placed into operation prior to the complete stabilization of its drainage area, provided that the basin's bottom during this period is constructed at a depth at least two feet higher than its final design elevation. All other infiltration BMP construction requirements in this section shall be followed. When the drainage area is completely stabilized, all accumulated sediment shall be removed from the infiltration BMP, which shall then be excavated to its final design elevation in accordance with the construction requirements of this section and the performance standards in § 184-4.
(b)
To avoid compaction of subgrade soils of BMPs that rely on infiltration,
no heavy equipment such as backhoes, dump trucks or bulldozers shall
be permitted to operate within the footprint of the BMP. All excavation
required to construct a stormwater infiltration BMP shall be performed
by equipment placed outside the BMP. If this is not possible, the
soils within the excavated area shall be renovated and tilled after
construction is completed to reverse the effects of compaction. In
addition, post-development soil permeability testing shall be performed
in accordance with Section B(5) of this section.
(c)
Earthwork associated with stormwater infiltration BMP construction,
including excavation, grading, cutting or filling, shall not be performed
when soil moisture content is above the lower plastic limit.
C.
Safety standards for structural stormwater management measures.
(1)
If a structural stormwater management measure has an outlet structure,
escape provisions shall be incorporated in or on the structure. "Escape
provisions" means the permanent installation of ladders, steps, rungs,
or other features that provide readily accessible means of ingress
and egress from the outlet structure.
(2)
A trash rack is a device intended to intercept runoff-borne trash
and debris that might otherwise block the hydraulic openings in an
outlet structure of a structural stormwater management measure. Trash
racks shall be installed upstream of such outlet structure openings
as necessary to ensure proper functioning of the structural stormwater
management measure in accordance with the following:
(a)
The trash rack should be constructed primarily of bars aligned
in the direction of flow with one-inch spacing between the bars to
the elevation of the water quality design storm. For elevations higher
than the water quality design storm, the bars shall be spaced no greater
than 1/3 the width of the hydraulic opening it is protecting or six
inches, whichever is less. Transverse bars aligned perpendicular to
flow should be sized and spaced as necessary for rack stability and
strength.
(b)
The trash rack shall not adversely affect the hydraulic performance
of either the outlet structure opening it is protecting or the overall
outlet structure.
(c)
The trash rack shall have sufficient net open area under clean
conditions to limit the peak design storm velocity through it to a
maximum of 2.5 feet per second.
(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.
(3)
An overflow grate is a device intended to protect the opening in
the top of a stormwater management measure outlet 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 more than two inches
across the smallest dimension; and
(c)
The overflow grate shall be constructed and installed to be
rigid, durable, and corrosion resistant and shall be designed to withstand
a perpendicular live loading of 300 pounds per square foot.
(4)
The maximum side slope for an earthen dam, embankment, or berm shall
not be steeper than three horizontal to one vertical (3:1).
(5)
Safety ledges.
(a)
Safety ledges shall be constructed on the slopes of all new structural stormwater management measures 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 feet to six feet in width. One step shall be located approximately 2 1/2 feet below the permanent water surface, and the second step shall be located one foot to 1 1/2 feet above the permanent water surface. See Subsection C(5)(b), below, for an illustration of safety ledges in a stormwater management basin.
(b)
Illustration of safety ledges.
 |
B.
General inspection, maintenance and repair plan.
(1)
The design engineer shall prepare an inspection, maintenance and repair plan for the stormwater management measures, including both structural and nonstructural measures incorporated into the design of a major development. This plan shall be submitted as part of the checklist requirements established in § 184-2C. Inspection and maintenance guidelines for stormwater management measures are available in the New Jersey BMP Manual.
(2)
The inspection, maintenance and repair plan shall contain the following:
(a)
Accurate and comprehensive drawings of the site's stormwater
management measures;
(b)
Specific locations of each stormwater management measure identified
by means of longitude and latitude as well as block and lot number;
(c)
Specific preventative and corrective maintenance tasks and schedules
for such tasks for each stormwater BMP;
(d)
Cost estimates, including estimated cost of sediment, debris
or trash removal; and
(e)
The name, address and telephone number of the person or persons
responsible for regular inspections and preventative and corrective
maintenance (including repair and replacement). If the responsible
person or persons is a corporation, company, partnership, firm, association,
municipality or political subdivision of this state, the name and
telephone number of an appropriate contact person shall also be included.
(3)
The person responsible for inspection, maintenance and repair identified under Subsection B(2) above shall maintain a detailed log of all preventative and corrective maintenance performed for the site's stormwater management measures, including a record of all inspections and copies of all maintenance-related work orders in the inspection, maintenance and repair plan. Said records and inspection reports shall be retained for a minimum of five years. (Note: Retention time is not addressed in N.J.A.C. 7:8, but five years is required for retention of data collected for monitoring under an NJPDES permit. The Pinelands Commission should consider what is an appropriate time frame for record retention, especially if staff is interested in pursuing future assessment of long-term BMP maintenance practices on water quality, etc.
(4)
If the inspection, maintenance and repair plan identifies a person
other than the developer (for example, a public agency or homeowners'
association) as having the responsibility for inspection and 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 measure to such person under an
applicable ordinance or regulation.
(5)
If the person responsible for inspection, maintenance and repair identified under Subsection B(2) above is not a public agency, the maintenance plan and any future revisions based on Subsection B(6) below shall be recorded upon the deed of record for each property on which the maintenance described in the maintenance plan shall be undertaken.
(6)
The person responsible for inspection, maintenance and repair identified under Subsection B(2) above shall evaluate the effectiveness of the inspection, maintenance and repair plan at least once per year and update the plan and the deed as needed.
(8)
The person responsible for inspection, maintenance and repair identified under Subsection B(2) above shall retain and make available, upon request by any public entity with administrative, health, environmental or safety authority over the site, the inspection, maintenance and repair plan and the documentation required by Subsection B(2) and (3) above.
C.
Responsibility for inspection, repair and 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.
D.
Preventative and corrective maintenance shall be performed to maintain
the function of the stormwater management measure, including, but
not limited to, repairs or replacement to any associated appurtenance
of the measure; removal of sediment, debris, or trash; restoration
of eroded areas; snow and ice removal; fence repair or replacement;
restoration of vegetation; repair or replacement of linings; and restoration
of infiltration function.
E.
Stormwater management measure easements shall be provided by the
property owner as necessary for facility inspections and maintenance
and preservation of stormwater runoff conveyance, infiltration, and
detention areas and facilities. The purpose of the easement shall
be specified in the maintenance agreement.
F.
In the event that the stormwater management measure becomes a public
health nuisance or danger to public safety or public health, or if
it is in need of maintenance or repair, the Borough of Wrightstown
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 Municipal
Engineer or the Municipal Engineer's designee. The Borough of
Wrightstown, at 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 within the allowable
time, the Borough of Wrightstown may immediately proceed to do so
with its own forces and equipment and/or through contractors. The
costs and expenses of such maintenance and repair by the Borough of
Wrightstown shall be entered on the tax roll as a special charge against
the property and collected with any other taxes levied thereon for
the year in which the maintenance and repair was performed.
G.
Requirements for inspection, maintenance and repair of stormwater
BMPs that rely on infiltration.
(1)
If a stormwater infiltration BMP is incorporated into the design
of a major development, the applicant shall include the following
requirements in its inspection, maintenance and repair plan:
(a)
Once per month (if needed): Mow side slopes, remove litter and debris,
stabilize eroded banks, repair erosion at inflow structure(s);
(b)
After every storm exceeding one inch of rainfall: Ensure that infiltration
BMPs drain completely within 72 hours after the storm event. If stored
water fails to infiltrate 72 hours after the end of the storm, corrective
measures shall be taken. Raking or tilling by light equipment can
assist in maintaining infiltration capacity and break up clogged surfaces;
(c)
Four times per year (quarterly): Inspect stormwater infiltration
BMPs for clogging and excessive debris and sediment accumulation within
the BMP, remove sediment (if needed) when completely dry;
(d)
Two times per year: Inspect for signs of damage to structures, repair
eroded areas, check for signs of petroleum contamination and remediate;
(e)
Once per year: Inspect BMPs for unwanted tree growth and remove if
necessary; disc or otherwise aerate bottom of infiltration basin to
a minimum depth of six inches; and
(f)
After every storm exceeding one inch of rainfall, inspect and, if
necessary, remove and replace K5 sand layer and accumulated sediment,
to restore original infiltration rate.
(2)
Additional guidance for the inspection, maintenance and repair of
stormwater infiltration BMPs can be found in the New Jersey BMP Manual.
H.
Financing of inspection, maintenance and repair of stormwater BMPs.
An adequate means of ensuring permanent financing of the inspection,
maintenance and repair of stormwater BMPs shall be implemented and
detailed in the inspection, maintenance and repair plan. Permanent
financing of the inspection, maintenance and repair of stormwater
BMPs shall be accomplished by:
(1)
The assumption of the inspection and maintenance program by an owner
of any commercial development or homeowners' association for
any residential development.
(2)
The
assumption of the inspection and maintenance program by the municipality
or county or utilities authority for any public development.
Unless specifically defined below, words or phrases used in
this article shall be interpreted so as to give them the meaning they
have in common usage and to give this article its most reasonable
application. When used in this article, the following terms shall
have the meanings herein ascribed to them:
The propagation, rearing and subsequent harvesting of aquatic
organisms in controlled or selected environments, and their subsequent
processing, packaging and marketing, including but not limited to
activities to intervene in the rearing process to increase production
such as stocking, feeding, transplanting and providing for protection
from predators.
The Planning Board, Zoning Board of Adjustment or other board,
agency or official of Borough of Wrightstown with authority to approve
or disapprove subdivisions, site plans, construction permits, building
permits or other applications for development approval. For the purposes
of reviewing development applications and ensuring compliance with
the requirements of this article, the Borough of Wrightstown may designate
the Municipal Engineer or other qualified designee to act on behalf
of the Borough of Wrightstown.
Either a written statement signed and sealed by a licensed
New Jersey professional engineer attesting that a BMP design or stormwater
management system conforms to or meets a particular set of standards
or action taken by the Commission pursuant to N.J.A.C. 7:50-3, Part
II or Part IV. Depending upon the context in which the term is used,
the terms "certify" and "certified" shall be construed accordingly.
The increase in soil bulk density caused by subjecting soil
to greater-than-normal loading. Compaction can also decrease soil
infiltration and permeability rates.
The construction, erection, reconstruction, alteration, conversion,
demolition, removal or equipping of buildings, structures or components
of a stormwater management system, including but not limited to collection
inlets, stormwater piping, swales and all other conveyance systems,
and stormwater BMPs.
An agency designated by the County Board of Chosen Freeholders
to review municipal stormwater management plans and implementing ordinance(s).
The county review agency may either be:
A person professionally qualified and duly licensed in New
Jersey to perform engineering services that may include, but not necessarily
be limited to, development of project requirements, creation and development
of project design and preparation of drawings and specifications.
The tested permeability rate with a factor of safety of two
applied to it (e.g., if the tested permeability rate of the soils
is four inches per hour, the design rate would be two inches per hour).
The change of or enlargement of any use or disturbance of any
land, the performance of any building or mining operation, the division
of land into two or more parcels, and the creation or termination
of rights of access or riparian rights, including, but not limited
to:
A change in type of use of a structure or land;
A reconstruction, alteration of the size, or material change
in the external appearance of a structure or land;
A material increase in the intensity of use of land, such as
an increase in the number of businesses, manufacturing establishments,
offices or dwelling units in a structure or on land;
Commencement of resource extraction or drilling or excavation
on a parcel of land;
Demolition of a structure or removal of trees;
Commencement of forestry activities;
Deposit of refuse, solid or liquid waste or fill on a parcel
of land;
In connection with the use of land, the making of any material
change in noise levels, thermal conditions, or emissions of waste
material; and
Alteration, either physically or chemically, of a shore, bank,
or floodplain, seacoast, river, stream, lake, pond, wetlands or artificial
body of water.
In the case of development on agricultural land, i.e., lands
used for an agricultural use or purpose as defined at N.J.A.C. 7:50-2.11,
"development" means any activity that requires a state permit; any
activity reviewed by the County Agricultural Board (CAB) and the State
Agricultural Development Committee (SADC), and municipal review of
any activity not exempted by the Right to Farm Act, N.J.S.A. 4:1C-1
et seq.
Any division of land into five or more lots; any construction
or expansion of any housing development of five or more dwelling units;
any construction or expansion of any commercial or industrial use
or structure on a site of more than three acres; or any development,
grading, clearing or disturbance of an area in excess of 5,000 square
feet. "Disturbance," for the purpose of this article, is the placement
of impervious surface or exposure and/or movement of soil or bedrock
or the clearing, cutting or removing of vegetation.
All development other than major development.
A geographic area within which stormwater, sediments, or
dissolved materials drain to a BMP, a stormwater management system,
a particular receiving water body or a particular point along a receiving
water body.
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 animal species;
threatened or endangered plants of the Pinelands pursuant to N.J.A.C.
7:50-6.27(a); large areas of contiguous open space or upland forest;
steep slopes; and wellhead protection and groundwater recharge areas.
"T and E habitat" constitutes habitat that is critical for the survival
of a local population of threatened and endangered species or habitat
that is identified using the Department's Landscape Project as
approved by the Department's Endangered and Nongame Species Program,
whichever is more inclusive. Threatened and endangered wildlife shall
be protected in conformance with N.J.A.C. 7:50-6.33.
The approval by the approving authority of a variance or
other material departure from strict compliance with any section,
part, phrase or provision of this article. An exception may be granted
only under certain specific, narrowly defined conditions described
herein and does not constitute a waiver of strict compliance with
any section, part, phrase or provision of the Pinelands Comprehensive
Management Plan (N.J.A.C. 7:50-1.1 et seq.).
A facility constructed through filling and/or excavation
that provides temporary storage of stormwater runoff. It has an outlet
structure that detains and attenuates runoff inflows and promotes
the settlement of pollutants. An extended detention basin is normally
designed as a multistage facility that provides runoff storage and
attenuation for both stormwater quality and quantity management. The
term "stormwater detention basin" shall have the same meaning as "extended
detention basin."
The elevation of the surface of the ground after completion
of final grading, either via cutting, filling or a combination thereof.
Modification of a land slope by cutting and filling with
the native soil or redistribution of the native soil which is present
at the site.
Water below the land surface in a zone of saturation.
A test performed to demonstrate that the groundwater below
a stormwater infiltration basin will not "mound up," encroach on the
unsaturated zone, break the surface of the ground at the infiltration
area or downslope, and create an overland flow situation.
Equipment, machinery, or vehicles that exert ground pressure
in excess of eight pounds per square inch.
An area in an industrial or commercial development site where
solvents and/or petroleum products are loaded/unloaded, stored, or
applied; where pesticides are loaded/unloaded or stored; 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; where recharge would be inconsistent with NJDEP-approved
remedial action work plan or landfill closure plan; and/or where a
high risk exists for spills of toxic materials, such as gas stations
and vehicle maintenance facilities. The term "HPLA" shall have the
same meaning as "high pollutant loading area."
A surface that has been covered with a layer of material
so that it is highly resistant to infiltration by water. Refer to
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
Table 2-2a, Runoff curve numbers for urban areas, "Impervious areas,"
for appropriate curve numbers.
Is the process by which precipitation enters the soil through
its surface.
A monetary fee collected by Borough of Wrightstown in lieu
of requiring strict on-site compliance with the groundwater recharge,
stormwater runoff quantity and/or stormwater runoff quality standards
established in this article.
To assemble, construct, put in place or connect components
of a stormwater management system.
Acts necessary to prevent, limit, remedy or compensate for
conditions that may result from those cases where an applicant has
demonstrated the inability or impracticality of strict compliance
with the stormwater management requirements set forth in N.J.A.C.
7:8, in an adopted regional stormwater management plan, or in a local
ordinance which is as protective as N.J.A.C. 7:8, and an exception
from strict compliance is granted by Borough of Wrightstown and the
Pinelands Commission.
Guidance developed by the New Jersey Department of Environmental
Protection, in coordination with the New Jersey Department of Agriculture,
the New Jersey Department of Community Affairs, the New Jersey Department
of Transportation, Municipal Engineers, county engineers, consulting
firms, contractors, and environmental organizations, to address the
standards in the New Jersey Stormwater Management Rules, N.J.A.C.
7:8. The BMP Manual provides examples of ways to meet the standards
contained in the rule. An applicant may demonstrate that other proposed
management practices will also achieve the standards established in
the rules. The manual, and notices regarding future versions of the
manual, are available from the Division of Watershed Management, NJDEP,
P.O. Box 418, Trenton, New Jersey 08625, and on the NJDEP's website,
www.njstormwater.org. The term "New Jersey BMP Manual" shall have
the same meaning as "New Jersey Stormwater Best Management Practices
Manual."
The New Jersey Department of Environmental Protection.
The New Jersey Pollutant Discharge Elimination System as
set forth in N.J.S.A. 58:10A-1 et seq. and in N.J.A.C. 7:14A.
A permit issued by the NJDEP pursuant to the authority of
the Water Pollution Control Act, N.J.S.A. 58:10A-1 et seq., and N.J.A.C.
7:14A for a discharge of pollutants.
Means:
Any human-made or human-induced activity, factor, or condition,
other than a point source, from which pollutants are or may be discharged;
Any human-made or human-induced activity, factor, or condition,
other than a point source, that may temporarily or permanently change
any chemical, physical, biological, or radiological characteristic
of waters of the state from what was or is the natural, pristine condition
of such waters or that may increase the degree of such change; or
Any activity, factor, or condition, other than a point source,
that contributes or may contribute to water pollution.
The term "NPS" shall have the same meaning as "nonpoint source."
A stormwater management measure, strategy or combination
of strategies that reduces adverse stormwater runoff impacts through
sound site planning and design. Nonstructural BMPs include such practices
as minimizing site disturbance, preserving important site features,
reducing and disconnecting impervious cover, flattening slopes, utilizing
native vegetation, minimizing turf grass lawns, maintaining natural
drainage features and characteristics and controlling stormwater runoff
and pollutants closer to the source. The term "low-impact development
technique" shall have the same meaning as "nonstructural BMP."
A chemical element or compound, such as nitrogen or phosphorus,
which is essential to and promotes the development of organisms.
The rate at which water moves through a saturated unit area
of soil or rock material at hydraulic gradient of one, determined
as prescribed in N.J.A.C. 7:9A-6.2, Tube permeameter test; N.J.A.C.
6.5, Pit-bailing test; or N.J.A.C. 6.6, Piezometer test. Alternative
permeability test procedures may be accepted by the approving authority,
provided that the test procedure attains saturation of surrounding
soils, accounts for hydraulic head effects on infiltration rates,
provides a permeability rate with units expressed in inches per hour
and is accompanied by a published source reference. Examples of suitable
sources include hydrogeology, geotechnical, or engineering text and
design manuals, proceedings of American Society for Testing and Materials
(ASTM) symposia, or peer-review journals. Neither a soil permeability
class rating test, as described in N.J.A.C. 7:9A-6.3, nor a percolation
test, as described in N.J.A.C. 7:9A-6.4, is an acceptable test for
establishing permeability values for the purpose of complying with
this article.
Having a permeability of one inch per hour or faster. The
terms "permeable soil," "permeable rock" and "permeable fill" shall
be construed accordingly.
Any individual, corporation, company, partnership, firm,
association, municipality or political subdivision of this state subject
to municipal jurisdiction pursuant to the Municipal Land Use Law,
N.J.S.A. 40:55D-1 et seq.
The New Jersey Pinelands Comprehensive Management Plan (N.J.A.C.
7:50-1.1 et seq.).
The Commission created pursuant Section 5 of the Pinelands
Protection Act, N.J.S.A. 13:18A-5.
Any discernible, confined, and discrete conveyance, including,
but not limited to, any pipe, ditch, channel, tunnel, conduit, well,
discrete fissure, container, rolling stock, concentrated animal feeding
operation, landfill leachate collection system, vessel, or other floating
craft, from which pollutants are or may be discharged. This term does
not include return flows from irrigated agriculture.
Any dredged spoil, solid waste, incinerator residue, filter
backwash, sewage, garbage, refuse, oil, grease, sewage sludge, munitions,
chemical wastes, biological materials, medical wastes, radioactive
substances [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, suspended solids, cellar
dirt, industrial, municipal, 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.
A person licensed to practice professional engineering in
the State of New Jersey pursuant to N.J.S.A. 45:8-27 et seq.
The amount of water from precipitation that infiltrates into
the ground and is not evapotranspired.
One of two or more soil samples or tests taken at the same
location (within five feet of each other) and depth, within the same
soil horizon or substratum. In the case of fill material, replicate
tests are tests performed on subsamples of the same bulk sample packed
to the same bulk density.
A particle size category consisting of mineral particles which are between 0.05 millimeter and 2.0 millimeters in equivalent spherical diameter. Also, a soil textural class having 85% or more of sand and a content of silt and clay such that the percentage of silt plus 1.5 times the percentage of clay does not exceed 15, as shown in § 184-11C(1) (USDA Soil Textural Triangle).
The upper limit of the shallowest zone of saturation which
occurs in the soil, identified as prescribed in N.J.A.C. 7:9A-5.8.
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 major development is to occur
or has occurred.
All unconsolidated mineral and organic material of any origin
which is not a rock substratum, including sediments below the biologically
active and/or weathered zones.
Any material(s) or machinery, located at an industrial facility,
that is directly or indirectly related to process, manufacturing or
other industrial activities, which could be a source of pollutants
in any industrial stormwater discharge to groundwater. Source materials
include, but are not limited to, raw materials; intermediate products;
final products; waste materials; by-products; industrial machinery
and fuels, and lubricants, solvents, and detergents that are related
to process, manufacturing, or other industrial activities that are
exposed to stormwater.
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.
A basin or other facility constructed within permeable soils
that provides temporary storage of stormwater runoff. An infiltration
BMP does not normally have a structural outlet to discharge runoff
from the stormwater quality design storm. Instead, outflow from an
infiltration BMP is through the surrounding soil. The terms "infiltration
measure" and "infiltration practice" shall have the same meaning as
"stormwater infiltration basin."
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. This includes,
but is not limited to, structural and nonstructural stormwater best
management practices described in the New Jersey BMP Manual and designed
to meet the standards for stormwater control contained within this
article. The terms "stormwater best management practice" and "stormwater
BMP" shall have the same meaning as "stormwater management measure."
Water flow on the surface of the ground or in storm sewers,
resulting from precipitation.
Unsaturated soil, above the seasonally high water table,
which contains less than 50% by volume of coarse fragments and which
has a tested permeability rate of between one inch and 20 inches per
hour.
Any waters of the state which are not groundwater.
A flood hazard area, which may be influenced by stormwater
runoff from inland areas, but which is primarily caused by the Atlantic
Ocean.
The time it takes for runoff to travel from the hydraulically
most distant point of the drainage area to the point of interest within
a watershed.
The insoluble solid matter suspended in water and stormwater
that is separable by laboratory filtration in accordance with the
procedure contained in the "Standard Methods for the Examination of
Water and Wastewater" prepared and published jointly by the American
Public Health Association, American Water Works Association and the
Water Pollution Control Federation. The term "TSS" shall have the
same meaning as "total suspended solids."
The ocean and its estuaries, all springs, streams and bodies
of surface water and groundwater, whether natural or artificial, within
the boundaries of New Jersey or subject to its jurisdiction.
The upper surface of a zone of saturation.
A bored, drilled or driven shaft, or a dug hole, which extends
below the seasonally high water table and which has a depth which
is greater than its largest surface dimension.
Those lands which are inundated or saturated by water at
a magnitude, duration and frequency sufficient to support the growth
of hydrophytes. Wetlands include lands with poorly drained or very
poorly drained soils as designated by the National Cooperative Soils
Survey of the Natural Resources Conservation Service of the United
States Department of Agriculture. Wetlands include coastal wetlands
and inland wetlands, including submerged lands. The "New Jersey Pinelands
Commission Manual for Identifying and Delineating Pinelands Area Wetlands:
A Pinelands Supplement to the Federal Manual for Identifying and Delineating
Jurisdictional Wetlands," dated January 1991, as amended, may be utilized
in delineating the extent of wetlands based on the definitions of
"wetlands" and "wetlands soils" contained in this section and N.J.A.C.
7:50-2.11, 7:50-6.4 and 7:50-6.5. The term "wetland" shall have the
same meaning as "wetlands."
A stormwater facility constructed through filling and/or
excavation that provides both permanent and temporary storage of stormwater
runoff. It has an outlet structure that creates a permanent pool and
detains and attenuates runoff inflows and promotes the settling of
pollutants. A stormwater retention basin can also be designed as a
multistage facility that also provides extended detention for enhanced
stormwater quality design storm treatment and runoff storage and attenuation
for stormwater quantity management. The term "stormwater retention
basin" shall have the same meaning as "wet pond."
This article shall take effect immediately upon the following:
If the provisions of any section, subsection, paragraph, subdivision,
or clause of this article 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 article.
A.
Methods for calculating groundwater recharge.
(1)
The New Jersey Geological Survey Report GSR-32: A Method for Evaluating
Ground-Water Recharge Areas in New Jersey. Available at http://www.njgeology.org/geodata/dgs99-2.htm.
(2)
The New Jersey Groundwater Recharge Spreadsheet (NJGRS). Available
in the New Jersey BMP Manual, Chapter 6, at http://www.njstormwater.org/bmp_manual2.htm.
B.
NJDEP nonstructural strategies point system. The New Jersey Stormwater Management Rules at N.J.A.C. 7:8-5.2(a) and § 184-4 of this article require nonstructural stormwater management strategies to be incorporated into the site design of a major development. A total of nine strategies are to be used to the maximum extent practical to meet the groundwater recharge, stormwater quality and stormwater quantity requirements of the Rules prior to utilizing structural stormwater management measures. The New Jersey Nonstructural Stormwater Management Strategies Point System (NSPS) provides a tool to assist planners, designers and regulators in determining that the strategies have been used to the maximum extent practical at a major development as required by the Rules. Refer online to http://www.njstormwater.org for information on the NSPS.
C.
Soils.
(1)
USDA Soil Textural Triangle.
 |
(2)
A-HORIZON
ARTESIAN ZONE OF SATURATION
CHROMA
CLAY
CLAY LOAM
COARSE FRAGMENT
COUNTY SOIL SURVEY REPORT
DIRECT SUPERVISION
EQUIVALENT SPHERICAL DIAMETER
EXCESSIVELY COARSE HORIZON
EXCESSIVELY COARSE SUBSTRATUM
EXTREMELY FIRM CONSISTENCE
FIRM CONSISTENCE
HARD CONSISTENCE
HUE
HYDRAULICALLY RESTRICTIVE HORIZON
HYDRAULICALLY RESTRICTIVE SUBSTRATUM
LOAMY SAND
LOWER PLASTIC LIMIT
MOTTLING
MUNSELL SYSTEM
O-HORIZON
PERCHED ZONE OF SATURATION
PIEZOMETER
PLATY STRUCTURE
REGIONAL ZONE OF SATURATION
SANDY CLAY
SANDY LOAM
SILT
SILT LOAM
SILTY CLAY
SILTY CLAY LOAM
SOIL AGGREGATE
SOIL COLOR
SOIL CONSISTENCE
SOIL HORIZON
SOIL LOG
SOIL MAPPING UNIT
SOIL PHASE
SOIL PROFILE
SOIL SERIES
SOIL STRUCTURAL CLASS
SOIL STRUCTURE
SOIL TEST PIT
SOIL TEXTURAL CLASS
SOIL TEXTURE
STATIC WATER LEVEL
SUBSTRATUM
UNSUITABLE SOIL
USDA SYSTEM OF CLASSIFICATION
VALUE
VERY FIRM CONSISTENCE
VERY HARD CONSISTENCE
ZONE OF SATURATION
Definitions. For the purposes of this appendix, the following terms
shall have the meanings herein ascribed to them:
The uppermost mineral horizon in a normal soil profile. The
upper part of the A-horizon is characterized by maximum accumulation
of finely divided, dark-colored organic residues, known as "humus,"
which are intimately mixed with the mineral particles of the soil.
A zone of saturation which exists immediately below a hydraulically
restrictive horizon and which has an upper surface which is at a pressure
greater than atmospheric, either seasonally or throughout the year.
The relative purity or strength of a color, a quantity which
decreases with increasing grayness. Chroma is one of the three variables
of soil color as defined in the Munsell system of classification.
A particle size category consisting of mineral particles which are smaller than 0.002 millimeter in equivalent spherical diameter. Also, a soil textural class having more than 40% clay, less than 45% sand, and less than 40% silt, as shown in § 184-11C(1) (USDA Soil Textural Triangle).
A soil textural class having 27% to 40% clay and 20% to 45% sand, as shown in § 184-11C(1) (USDA Soil Textural Triangle).
A rock fragment contained within the soil which is greater
than two millimeters in equivalent spherical diameter or which is
retained on a two-millimeter sieve.
A report prepared by the U.S. Department of Agriculture,
Natural Resources Conservation Service, which includes maps showing
the distribution of soil mapping units throughout a particular county
together with narrative descriptions of the soil series shown and
other information relating to the uses and properties of the various
soil series.
Control over and direction of work carried out by others
with full knowledge of and responsibility for such work.
Of a particle, means the diameter of a sphere which has a
volume equal to the volume of the particle.
A horizon of limited thickness within the soil profile which
provides inadequate removal of pollutants from stormwater due to a
high coarse fragment content, excessively coarse texture and/or excessively
rapid permeability.
A substratum below the soil profile which extends beyond
the depth of soil profile pits and borings and which provides inadequate
removal of pollutants from stormwater due to a high coarse fragment
content, excessively coarse texture and/or excessively rapid permeability.
A type of soil material whose moist aggregated mass crushes
only under very strong pressure; cannot be crushed between the thumb
and forefinger and shall be broken apart bit by bit.
A type of soil material whose moist aggregated mass crushes
under moderate pressure between the thumb and forefinger but resistance
is distinctly noticeable.
A type of soil material whose dry aggregated mass is moderately
resistant to pressure; can be broken in the hands without difficulty
but is barely breakable between the thumb and forefinger.
The dominant spectral color, one of the three variables of
soil color defined within the Munsell system of classification.
A horizon within the soil profile which slows or prevents
the downward or lateral movement of water and which is underlain by
permeable soil horizons or substrata. Any soil horizon which has a
saturated permeability less than one inch per hour is hydraulically
restrictive.
A substratum below the soil profile which slows or prevents
the downward or lateral movement of water and which extends beyond
the depth of profile pits or borings or to a massive substratum. A
substratum which has a saturated permeability less than one inch per
hour is hydraulically restrictive.
A soil textural class, as shown in § 184-11C(1) (USDA Soil Textural Triangle), that has a maximum of 85% to 90% sand with a percentage of silt plus 1.5 times the percentage of clay not in excess of 15, or a minimum of 70% to 85% sand with a percentage of silt plus 1.5 times the percentage of clay not in excess of 30.
The moisture content corresponding to the transition between
the plastic and semisolid states of soil consistency. This corresponds
to the lowest soil moisture content at which the soil can be molded
in the fingers to form a rod or wire, 1/8 inch in thickness, without
crumbling.
A color pattern observed in soil consisting of blotches or
spots of contrasting color. The term "mottle" refers to an individual
blotch or spot. The terms "color variegation," "iron depletion" and
"iron concentration" are equivalent to the term "mottling." Mottling
due to redoximorphic reactions is an indication of seasonal or periodic
and recurrent saturation.
A system of classifying soil color consisting of an alphanumeric
designation for hue, value and chroma, such as "7.5 YR 6/2," together
with a descriptive color name, such as "strong brown."
A surface horizon, occurring above the A-horizon in some
soils, which is composed primarily of undecomposed or partially decomposed
plant remains which have not been incorporated into the mineral soil.
A zone of saturation which occurs immediately above a hydraulically
restrictive horizon and which is underlain by permeable horizons or
substrata which are not permanently or seasonally saturated.
A device consisting of a length of metal or plastic pipe,
open at the bottom or perforated within a specified interval, and
used for the determination of depth to water, permeability or hydraulic
head within a specific soil horizon or substratum.
Is characterized by a soil aggregate which has one axis distinctly
shorter than the other two and are oriented with the short axis vertical.
A zone of saturation which extends vertically without interruption
below the depth of soil borings and profile pits.
A soil textural class having 35% or more of clay and 45% or more of sand, as shown in § 184-11C(1) (USDA Soil Textural Triangle).
A soil textural class, as shown in § 184-11C(1) (USDA Soil Textural Triangle), that has a maximum of 20% clay, and the percentage of silt plus twice the percentage of clay exceeds 30, and contains 52% or more sand; or less than 7% clay, less than 50% silt, and between 43% and 52% sand.
A particle size category consisting of mineral particles which are between 0.002 millimeter and 0.05 millimeter in equivalent spherical diameter. It also means a soil textural class having 80% or more of silt and 12% or less of clay, as shown in § 184-11C(1) (USDA Soil Textural Triangle).
A soil textural class having 50% or more of silt and 12% to 27% of clay, or 50% to 80% of silt and less than 12% of clay, as shown in § 184-11C(1) (USDA Soil Textural Triangle).
A soil textural class having 40% or more of clay and 40% or more of silt, as shown in § 184-11C(1) (USDA Soil Textural Triangle).
A soil textural class having 27% to 40% of clay and less than 20% of sand, as shown in § 184-11C(1) (USDA Soil Textural Triangle).
A naturally occurring unit of soil structure consisting of
particles of sand, silt, clay, organic matter, and coarse fragments
held together by the natural cohesion of the soil.
The soil color name and Munsell color designation determined
by comparison of the moist soil with color chips contained in a Munsell
soil color book.
The resistance of a soil aggregate or clod to being crushed
between the fingers or broken by the hands. Terms for describing soil
consistence described are in N.J.A.C. 7:9A-5.3(h).
A layer within a soil profile differing from layers of soil
above and below it in one or more of the soil morphological characteristics,
including color, texture, coarse fragment content, structure, consistence
and mottling.
A description of the soil profile which includes the depth,
thickness, color, texture, coarse fragment content, mottling, structure
and consistence of each soil horizon or substratum.
An area outlined on a map in a county soil survey report
and marked with a letter symbol designating a soil phase, a complex
of two or more soil phases, or some other descriptive term where no
soil type has been identified.
A specific type of soil which is mapped by the Natural Resources
Conservation Service and which belongs to a soil series described
within the county soil survey report.
A vertical cross section of undisturbed soil showing the
characteristic horizontal layers or horizons of the soil which have
formed as a result of the combined effects of parent material, topography,
climate, biological activity and time.
A grouping of soil types possessing a specific range of soil
profile characteristics which are described within the county soil
survey report. Each soil series may consist of several soil phases
which may differ in slope, texture of the surface horizon or stoniness.
One of the shape classes of soil structure described in N.J.A.C.
7:9A-5.3(g).
The naturally occurring arrangement, within a soil horizon,
of sand, silt and clay particles, coarse fragments and organic matter,
which are held together in clusters or aggregates of similar shape
and size.
An excavation made for the purpose of exposing a soil profile
which is to be described.
One of the classes of soil texture defined within the USDA
system of classification. (Soil Survey Manual, Agricultural Handbook
No. 18, USDA Soil Conservation Service 1962.)
The relative proportions of sand, silt and clay in that portion
of the soil which passes through a sieve with two-millimeter openings.
The depth below the ground surface or the elevation with
respect to some reference level, of the water level observed within
a soil profile pit or boring, or within a piezometer, after this level
has stabilized or become relatively constant with the passage of time.
A layer of soil or rock material present below the soil profile
and extending beyond the depth of soil borings or profile pits.
All soil other than suitable soil.
The system of classifying soil texture used by the United States Department of Agriculture which defines 12 soil textural classes based upon the weight percentages of sand, silt and clay in that portion of the soil which passes through a sieve with two-millimeter openings. The soil textural classes are shown graphically on the USDA Soil Textural Triangle, as shown in § 184-11C(1).
The relative lightness or intensity of a color, one of the
three variables of soil color defined within the Munsell system of
classification.
Is characterized by a moist soil which crushes under strong
pressure; barely crushable between thumb and forefinger.
Is characterized by a dry soil which is resistant to pressure,
can be broken in the hands only with difficulty; not breakable between
the thumb and forefinger.
A layer within or below the soil profile which is saturated
with groundwater either seasonally or throughout the year. This includes
both regional and perched zones.
(3)
Methods for assessing soil suitability for infiltration stormwater
management BMPs. The results of a subsurface investigation shall serve
as the basis for the site selection and design of stormwater infiltration
BMPs. The subsurface investigation shall include, but not be limited
to, a series of soil test pits and soil permeability tests conducted
in accordance with the following:
(a)
All soil test pits and soil permeability results shall be performed
under the direct supervision of a professional engineer. All soil
logs and permeability test data shall be accompanied by a certification
by a professional engineer. The results and location (horizontal and
vertical) of all soil test pits and soil permeability tests, both
passing and failing, shall be reported to the Borough of Wrightstown.
(b)
During all subsurface investigations and soil test procedures,
adequate safety measures shall be taken to prohibit unauthorized access
to the excavations at all times. It is the responsibility of persons
performing or witnessing subsurface investigations and soil permeability
tests to comply with all applicable federal, state and local laws
and regulations governing occupational safety.
(c)
A minimum of two soil test pits shall be excavated within the
footprint of any proposed infiltration BMP to determine the suitability
and distribution of soil types present at the site. Placement of the
test pits shall be within 20 feet of the basin perimeter, located
along the longest axis bisecting the BMP. For BMPs larger than 10,000
square feet in area, a minimum of one additional soil test pit shall
be conducted within each additional area of 10,000 square feet. The
additional test pit(s) shall be placed approximately equidistant to
other test pits, so as to provide adequate characterization of the
subsurface material. In all cases, where soil and or groundwater properties
vary significantly, additional test pits shall be excavated in order
to accurately characterize the subsurface conditions below the proposed
infiltration BMP. Soil test pits shall extend to a minimum depth of
eight feet below the lowest elevation of the basin bottom or to a
depth that is at least two times the maximum potential water depth
in the proposed infiltration BMP, whichever is greater.
(d)
A soil test pit log shall be prepared for each soil test pit.
The test pit log shall, at a minimum, provide the elevation of the
existing ground surface, the depth and thickness (in inches) of each
soil horizon or substratum, the dominant matrix or background and
mottle colors using the Munsell system of classification for hue,
value and chroma, the appropriate textural class as shown on the USDA
Textural Triangle, the volume percentage of coarse fragments (larger
than two millimeters in diameter), the abundance, size, and contrast
of mottles, the soil structure, soil consistence, and soil moisture
condition, using standard USDA classification terminology for each
of these soil properties. Soil test pit logs shall identify the presence
of any soil horizon, substratum or other feature that exhibits an
in-place permeability rate less than one inch per hour.
(e)
Each soil test pit log shall report the depth to seasonally
high water level, either perched or regional, and the static water
level based upon the presence of soil mottles or other redoximorphic
features, and observed seepage or saturation. Where redoximorphic
features including soil mottles resulting from soil saturation are
present, they shall be interpreted to represent the depth to the seasonal
high water table unless soil saturation or seepage is observed at
a higher level. When the determination of the seasonally high water
table shall be made in ground previously disturbed by excavation,
direct observation of the static water table during the months of
January through April shall be the only method permitted.
(f)
Any soil horizon or substratum which exists immediately below
a perched zone of saturation shall be deemed by rule to exhibit unacceptable
permeability (less than one inch per hour). The perched zone of saturation
may be observed directly, inferred based upon soil morphology, or
confirmed by performance of a hydraulic head test as defined at N.J.A.C.
7:9A-5.9.
(g)
Stormwater infiltration BMPs shall not be installed in soils
that exhibit artesian groundwater conditions. A permeability test
shall be conducted in all soils that immediately underlie a perched
zone of saturation. Any zone of saturation which is present below
a soil horizon which exhibits an in-place permeability of less than
0.2 inch per hour shall be considered an artesian zone of saturation
unless a minimum one-foot-thick zone of unsaturated soil, free of
mottling or other redoximorphic features and possessing a chroma of
four or higher, exists immediately below the unsuitable soil.
(h)
A minimum of one permeability test shall be performed at each
soil test pit location. The soil permeability rate shall be determined
using test methodology as prescribed in N.J.A.C. 7:9A-6.2, Tube permeameter
test; 7:9A-6.5, Pit-bailing test; or 7:9A-6.6, Piezometer test. When
the tube permeameter test is used, a minimum of two replicate samples
shall be taken and tested. Alternative permeability test procedures
may be accepted by the approving authority, provided that the test
procedure attains saturation of surrounding soils, accounts for hydraulic
head effects on infiltration rates, provides a permeability rate with
units expressed in inches per hour and is accompanied by a published
source reference. Examples of suitable sources include hydrogeology,
geotechnical or engineering text and design manuals, proceedings of
American Society for Testing and Materials (ASTM) symposia, or peer-review
journals. Neither a soil permeability class rating test, as described
in N.J.A.C. 7:9A-6.3, nor a percolation test, as described in N.J.A.C.
7:9A-6.4, is an acceptable test for establishing permeability values
for the purpose of complying with this article.
(i)
Soil permeability tests shall be conducted on the most hydraulically
restrictive horizon or substratum to be left in place below the basin
as follows. Where no soil replacement is proposed, the permeability
tests shall be conducted on the most hydraulically restrictive horizon
or substratum within four feet of the lowest elevation of the basin
bottom or to a depth equal to two times the maximum potential water
depth within the basin, whichever is greater. Where soil replacement
is proposed, the permeability tests shall be conducted within the
soil immediately below the depth of proposed soil replacement or within
the most hydraulically restrictive horizon or substratum to a depth
equal to two times the maximum potential water depth within the basin,
whichever is greater. Permeability tests may be performed on the most
hydraulically restrictive soil horizons or substrata at depths greater
than those identified above based upon the discretion of the design
or testing engineer. The tested infiltration rate should then be divided
by two to establish the soil's design permeability rate. Such
division will provide a safety factor of 100% to the tested rate.
(j)
The minimum acceptable tested permeability rate of any soil
horizon or substratum shall be one inch per hour. Soil materials that
exhibit tested permeability rates slower than one inch per hour shall
be considered unsuitable for stormwater infiltration. The maximum
reportable tested permeability rate of any soil horizon or substratum
shall be no greater than 20 inches per hour regardless of the rate
attained in the test procedure.
(k)
After all construction activities have been completed on the
development site and the finished grade has been established in the
infiltration BMP, a minimum of one permeability test shall be conducted
within the most hydraulically restrictive soil horizon or substratum
below the as-built BMP to ensure the performance of the infiltration
BMP is as designed. Hand tools and manual permeability test procedures
shall be used for the purpose of confirming BMP performance. In addition,
the infiltration BMP shall be flooded with water sufficient to demonstrate
the performance of the BMP. Test results shall be certified to the
Municipal Engineer.
(l)
A groundwater mounding analysis shall be provided for each stormwater
infiltration BMP. The groundwater mounding analysis shall calculate
the maximum height of the groundwater mound based upon the volume
of the maximum design storm. The professional engineer conducting
the analysis shall provide the Municipal Engineer with the methodology
and supporting documentation for the mounding analysis used and shall
certify to the Borough of Wrightstown, based upon the analysis, that
the groundwater mound will not cause stormwater or groundwater to
break out to the land surface or cause adverse impact to adjacent
surface water bodies, wetlands or subsurface structures, including
but not limited to basements and septic systems. If there is more
than one infiltration BMP proposed, the model shall indicate if and
how the mounds will interact. The mounding analysis shall be calculated
using the most restrictive soil horizon that will remain in place
within the explored aquifer thickness unless alternative analysis
is authorized by the Municipal Engineer. The mounding analysis shall
be accompanied by a cross section of the infiltration BMP and surrounding
topography and the mound analysis shall extend out to the point(s)
at which the mound intersects with the preexisting maximum water table
elevation.
D.
Pretreatment measures for infiltration BMPs. By reducing incoming
velocities and capturing coarser sediments, pretreatment can extend
the functional life and increase the pollutant removal capability
of infiltration measures. Therefore, the installation of pretreatment
measures is recommended for all development sites. Pretreatment measures
may include, but are not limited to, the following:
E.
Collection and conveyance.
(1)
Bicycle-safe inlet grates. Site development plans that incorporate
site design features that help 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.
(a)
Design engineers shall use either of the following grates whenever
they use a grate in pavement or another ground surface to collect
stormwater from that surface into a storm drain or surface water body
under that grate:
[1]
The New Jersey Department of Transportation (NJDOT) bicycle-safe
grate, which is described in Chapter 2.4 of the NJDOT Bicycle Compatible
Roadways and Bikeways Planning and Design Guidelines (April 1996);
or
[2]
A different grate, if each individual clear space in that grate
has an area of no more than seven 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.
(b)
Whenever design engineers use a curb-opening inlet, the clear
space in that curb opening (or each individual clear space, if the
curb opening has two or more clear spaces) shall have an area of no
more than seven square inches or be no greater than two inches across
the smallest dimension.
(c)
This standard does not apply:
[1]
Where the review agency determines that this standard would
cause inadequate hydraulic performance that could not practicably
be overcome by using additional or larger storm drain inlets that
meet these standards;
[2]
Where flows from the water quality design storm as specified in § 184-3 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:
[3]
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 § 184-3 of this article; or
[4]
Where the NJDEP 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.
(2)
Catch basins. Catch basins are storm drain inlets with or without
sumps. Catch basins may provide pretreatment for other stormwater
BMPs by capturing large sediments. The sediment and pollutant removal
efficiency of catch basins depends on the size of the sump and the
performance of routine maintenance to retain the available sediment
storage space in the sump. Where catch basins with sumps are proposed,
the minimum two feet of separation between the bottom of the sump
and the seasonally high water table shall be provided.
(3)
Open or perforated conveyance piping. Where adequate separation to
the seasonal high water table exists, stormwater from the development
site may be conveyed to a stormwater basin via a system of perforated
pipes. These pipes may be made of PVC or corrugated metal and are
available with perforations of varying size and spacing. Perforated
pipe specifications shall be certified by a professional engineer.
A professional engineer shall certify that perforated conveyance piping
will not act to intercept the seasonal high water table and convey
groundwater to the stormwater basin. All open or perforated stormwater
conveyance systems shall be installed with a minimum separation of
two feet from the seasonal high water table.
A.
NJDEP technical guidance sources.
(1)
New Jersey BMP Manual. Available from the Division of Watershed Management,
New Jersey Department of Environmental Protection, P.O. Box 418, Trenton,
New Jersey 08625, or online at http://www.njstormwater.org.
(2)
NJDEP Stormwater Management Facilities Maintenance Manual. Available
from the Division of Watershed Management, New Jersey Department of
Environmental Protection, P.O. Box 418, Trenton, New Jersey 08625,
or online at http://njedl.rutgers.edu/ftp/PDFs/1188.pdf.
B.
Additional guidance sources.
(1)
New Jersey Pinelands Commission, P.O. Box 7, 15 Springfield Road,
New Lisbon, New Jersey 08064; phone: 609-894-7300; website: http://www.state.nj.us/pinelands.
(2)
State Soil Conservation Committee Standards for Soil Erosion and
Sediment Control in New Jersey. Available from all State Soil Conservation
Districts, including Burlington County Soil Conservation District,
Tiffany Square, Suite 100, 1289 Route 38, Hainesport, New Jersey 08036;
phone: 609-267-7410; fax: 609-267-3347; website: http://bscd.org.
(3)
State soil conservation districts. Burlington County Soil Conservation
District.
(4)
New Jersey Department of Transportation, P.O. Box 600, Trenton, New
Jersey 08625-0600; phone: 609-530-3536; website: http://www.state.nj.us/transportation.
[Adopted 9-12-2007 by Ord. No. 2007-09]
A.
Policy statement. Flood control, groundwater recharge, and pollutant
reduction through nonstructural or low-impact techniques shall be
explored before relying on structural BMPs. Structural BMPs should
be integrated with nonstructural stormwater management strategies
and proper maintenance plans. Nonstructural strategies include both
environmentally sensitive site design and source controls that prevent
pollutants from being placed on the site or from being exposed to
stormwater. Source control plans should be developed based upon physical
site conditions and the origin, nature, and the anticipated quantity
or amount of potential pollutants. Multiple stormwater management
BMPs may be necessary to achieve the established performance standards
for water quality, quantity, and groundwater recharge.
B.
Purpose. It is the purpose of this article to establish minimum stormwater management requirements and controls for major development, as defined in § 184-14.
C.
Applicability.
D.
Compatibility with other permit and ordinance requirements. Development
approvals issued for subdivisions and site plans pursuant to this
article 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 article shall be held to be the minimum requirements for the
promotion of the public health, safety, and general welfare. This
article is not intended to interfere with, abrogate, or annul any
other ordinances, rule or regulation, statute, or other provision
of law except that, where any provision of this article 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 article shall be interpreted so as to give them the meaning they
have in common usage and to give this article 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, unless modified specifically for the Borough of Wrightstown.
The increase in soil bulk density.
A pedestrian-oriented area of commercial and civic uses serving
the surrounding municipality, generally including housing and access
to public transportation.
An agency designated by the County Board of Chosen Freeholders
to review municipal stormwater management plans and implementing ordinance(s).
The county review agency may either be:
The New Jersey Department of Environmental Protection.
A State Development and Redevelopment Plan Center as designated
by the State Planning Commission such as urban, regional, town, village,
or hamlet.
A person professionally qualified and duly licensed in New
Jersey to perform engineering services that may include, but not necessarily
be limited to, development of project requirements, creation and development
of project design and preparation of drawings and specifications.
The division of a parcel of land into two or more parcels,
the construction, reconstruction, conversion, structural alteration,
relocation or enlargement of any building or structure, any mining
excavation or landfill, and any use or change in the use of any building
or other structure, or land or extension of use of land, by any person,
for which permission is required under the Municipal Land Use Law,
N.J.S.A. 40:55D-1 et seq. In the case of development of agricultural
lands, development means: any activity that requires a state permit;
any activity reviewed by the County Agricultural Board (CAB) and the
State Agricultural Development Committee (SADC), and municipal review
of any activity not exempted by the Right to Farm Act, N.J.S.A 4:1C-1
et seq.
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.
A neighborhood designated by the Urban Coordinating Council
"in consultation and conjunction with" the New Jersey Redevelopment
Authority pursuant to N.J.S.A 55:19-69.
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 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.
Any development that provides for ultimately disturbing one
or more acres of land or more than 10,000 square feet of new impervious
coverage. Disturbance for the purpose of this rule is the placement
of impervious surface or exposure and/or movement of soil or bedrock
or the clearing, cutting, or removing of vegetation.
The Borough of Wrightstown.
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 Borough of Wrightstown, or political subdivision
of this state subject to municipal jurisdiction pursuant to the Municipal
Land Use Law, N.J.S.A. 40:55D-1 et seq.
Any dredged spoil, solid waste, incinerator residue, filter
backwash, sewage, garbage, refuse, oil, grease, sewage sludge, munitions,
chemical wastes, biological materials, medical wastes, radioactive
substances [except those regulated under the Atomic Energy Act of
1954, as amended (42 U.S.C. § 2011 et seq.)], thermal waste,
wrecked or discarded equipment, rock, sand, cellar dirt, industrial,
municipal, agricultural, and construction waste or runoff, or other
residue discharged directly or indirectly to the land, 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.
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 major development is to occur
or has occurred.
All unconsolidated mineral and organic material of any origin.
An area delineated on the State Plan Policy Map and adopted
by the State Planning Commission that is intended to be the focus
for much of the state's future redevelopment and revitalization
efforts.
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.
Water flow on the surface of the ground or in storm sewers,
resulting from precipitation.
A flood hazard area, which may be influenced by stormwater
runoff from inland areas, but which is primarily caused by the Atlantic
Ocean.
A neighborhood given priority access to state resources through
the New Jersey Redevelopment Authority.
A zone designated by the New Jersey Enterprise Zone Authority
pursuant to the New Jersey Urban Enterprise Zones Act, N.J.S.A. 52:27H-60
et seq.
Is defined as previously developed portions of areas:
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.
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.
Stormwater management measures for major development shall be developed to meet the erosion control, groundwater recharge, stormwater runoff quantity, and stormwater runoff quality standards in § 184-16. 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.
B.
The standards in this article apply only to new major development
and are intended to minimize the impact of stormwater runoff on water
quality and water quantity in receiving water bodies and maintain
groundwater recharge. The standards do not apply to new major development
to the extent that alternative design and performance standards are
applicable under a regional stormwater management plan or water quality
management plan adopted in accordance with Department rules. The stormwater
management requirements within this article, as they relate to major
development, supersede other design requirements stipulated in the
Borough Code, including but not limited to the following section(s):
A.
The development shall incorporate a maintenance plan for the stormwater management measures incorporated into the design of a major development in accordance with § 184-22.
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 muhlenbergi (bog turtle).
C.
The following linear development projects are exempt from the groundwater recharge, stormwater runoff quantity, and stormwater runoff quality requirements of § 184-16F and G:
(1)
The construction of an underground utility line, provided that the
disturbed areas are revegetated upon completion;
(2)
The construction of an aboveground utility line, provided that the
existing conditions are maintained to the maximum extent practicable;
and
(3)
The construction of a public pedestrian access, such as a sidewalk
or trail with a maximum width of 14 feet, provided that the access
is made of permeable material.
D.
A waiver from strict compliance from the groundwater recharge, stormwater runoff quantity, and stormwater runoff quality requirements of § 184-16F and G may be obtained for the enlargement of an existing public roadway or railroad, or the construction or enlargement of a public pedestrian access, provided that the following conditions are met:
(1)
The applicant demonstrates that there is a public need for the project
that cannot be accomplished by any other means;
(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 § 184-16F and G that were not achievable on site.
E.
Nonstructural stormwater management strategies.
(1)
To the maximum extent practicable, the standards in § 184-16F and G shall be met by incorporating nonstructural stormwater management strategies set forth at § 184-16E 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)
Nonstructural stormwater management strategies incorporated into
site design shall:
(a)
Protect areas that provide water quality benefits or areas particularly
susceptible to erosion and sediment loss;
(b)
Minimize impervious surfaces and break up or disconnect the
flow of runoff over impervious surfaces;
(c)
Maximize the protection of natural drainage features and vegetation;
(d)
Minimize the decrease in the time of concentration from pre-construction
to post-construction. "Time of concentration" is defined as the time
it takes for runoff to travel from the hydraulically most distant
point of the watershed to the point of interest within a watershed;
(e)
Minimize land disturbance, including clearing and grading;
(f)
Minimize soil compaction;
(g)
Provide low-maintenance landscaping that encourages retention
and the planting of native vegetation and minimizes the use of lawns,
fertilizers and pesticides;
(h)
Provide vegetated open-channel conveyance systems discharging
into and through stable vegetated areas;
(i)
Provide other source controls to prevent or minimize the use
or exposure of pollutants at the site, in order to prevent or minimize
the release of those pollutants into stormwater runoff. Such source
controls include, but are not limited to:
[1]
Site design features that help to prevent accumulation of trash and debris in drainage systems, including features that satisfy § 184-16E(3) below;
[2]
Site design features that help to prevent discharge of trash
and debris from drainage systems;
[3]
Site design features that help to prevent and/or contain spills
or other harmful accumulations of pollutants at industrial or commercial
developments; and
[4]
When establishing vegetation after land disturbance, applying
fertilizer in accordance with the requirements established under the
Soil Erosion and Sediment Control Act, N.J.S.A. 4:24-39 et seq., and
implementing rules.
(3)
Site design features identified under § 184-16E(2)(i)[2] above shall comply with the following standard to control passage of solid and floatable materials through storm drain inlets. For purposes of this subsection, "solid and floatable materials" means sediment, debris, trash, and other floating, suspended, or settleable solids. For exemptions to this standard, see § 184-16E(3)(c) below.
(a)
Grates.
[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
(April 1996); or
[b]
A different grate, if each individual clear space
in that grate has an area of no more than seven square inches or is
no greater than 0.5 inch across the smallest dimension.
[2]
Examples of grates subject to this standard include grates in
grate inlets, the grate portion (non-curb-opening portion) of combination
inlets, grates on storm sewer manholes, ditch grates, trench grates,
and grates of spacer bars in slotted drains. Examples of ground surfaces
include surfaces of roads (including bridges), driveways, parking
areas, bikeways, plazas, sidewalks, lawns, fields, open channels,
and stormwater basin floors.
(b)
Whenever design engineers use a curb-opening inlet, the clear space
in that curb opening (or each individual clear space, if the curb
opening has two or more clear spaces) shall have an area of no more
than seven square inches or be no greater than two inches across the
smallest dimension.
(c)
This standard does not apply:
[1]
Where the review agency determines that this standard would cause
inadequate hydraulic performance that could not practicably be overcome
by using additional or larger storm drain inlets that meet these standards;
[2]
Where flows from the water quality design storm as specified in § 184-16G(1) are conveyed through any device (e.g., end of pipe netting facility, manufactured treatment device, or a catch basin hood) that is designed, at a minimum, to prevent delivery of all solid and floatable materials that could not pass through one of the following:
[3]
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 § 184-16G(1); or
[4]
Where the New Jersey Department of Environmental Protection determines,
pursuant to the New Jersey Register of Historic Places Rules at N.J.A.C.
7:4-7.2(c), that action to meet this standard is an undertaking that
constitutes an encroachment or will damage or destroy the New Jersey
Register listed historic property.
(4)
Any land area used as a nonstructural stormwater management measure to meet the performance standards in § 184-16F and G shall be dedicated to a government agency, subjected to a conservation restriction filed with the appropriate County Clerk's office, or subject to an approved equivalent restriction that ensures that measure or an equivalent stormwater management measure approved by the reviewing agency is maintained in perpetuity.
F.
Erosion control, groundwater recharge and runoff quantity standards.
(1)
This subsection contains minimum design and performance standards
to control erosion, encourage and control infiltration and groundwater
recharge, and control stormwater runoff quantity impacts of major
development.
(a)
The minimum design and performance standards for erosion control
are those established under the Soil Erosion and Sediment Control
Act, N.J.S.A. 4:24-39 et seq. and implementing rules.
(b)
The minimum design and performance standards for groundwater
recharge are as follows:
[1]
The design engineer shall, using the assumptions and factors for stormwater runoff and groundwater recharge calculations at § 184-17, either:
[a]
Demonstrate through hydrologic and hydraulic analysis
that the site and its stormwater management measures maintain 100%
of the average annual pre-construction groundwater recharge volume
for the site; or
[b]
Demonstrate through hydrologic and hydraulic analysis
that the increase of stormwater runoff volume from pre-construction
to post-construction for the two-year storm is infiltrated.
[2]
This groundwater recharge requirement does not apply to projects within the urban redevelopment area or to projects subject to Subsection F(1)(b)[3] below.
[3]
The following types of stormwater shall not be recharged:
[a]
Stormwater from areas of high pollutant loading.
High pollutant loading areas are areas in industrial and commercial
developments where solvents and/or petroleum products are loaded/unloaded,
stored, or applied; areas where pesticides are loaded/unloaded or
stored; areas where hazardous materials are expected to be present
in greater than "reportable quantities" as defined by the United States
Environmental Protection Agency (EPA) at 40 CFR 302.4; areas where
recharge would be inconsistent with Department-approved remedial action
work plan or landfill closure plan; and areas with high risks for
spills of toxic materials, such as gas stations and vehicle maintenance
facilities; and
[b]
Industrial stormwater exposed to source material.
"Source material" means any material(s) or machinery, located at an
industrial facility, that is directly or indirectly related to process,
manufacturing or other industrial activities, which could be a source
of pollutants in any industrial stormwater discharge to groundwater.
Source materials include, but are not limited to, raw materials; intermediate
products; final products; waste materials; by-products; industrial
machinery and fuels; and lubricants, solvents, and detergents that
are related to process, manufacturing, or other industrial activities
that are exposed to stormwater.
[4]
The design engineer shall assess the hydraulic impact on the
groundwater table and design the site so as to avoid adverse hydraulic
impacts. Potential adverse hydraulic impacts include, but are not
limited to, exacerbating a naturally or seasonally high water table
so as to cause surficial ponding, flooding of basements, or interference
with the proper operation of subsurface sewage disposal systems and
other subsurface structures in the vicinity or downgradient of the
groundwater recharge area.
(c)
In order to control stormwater runoff quantity impacts, the design engineer shall, using the assumptions and factors for stormwater runoff calculations at § 184-17, complete one of the following:
[1]
Demonstrate through hydrologic and hydraulic analysis that for
stormwater leaving the site, post-construction runoff hydrographs
for the two-, ten-, and one-hundred-year storm events do not exceed,
at any point in time, the pre-construction runoff hydrographs for
the same storm events;
[2]
Demonstrate through hydrologic and hydraulic analysis that there
is no increase, as compared to the pre-construction condition, in
the peak runoff rates of stormwater leaving the site for the two-,
ten-, and one-hundred-year storm events and that the increased volume
or change in timing of stormwater runoff will not increase flood damage
at or downstream of the site. This analysis shall include the analysis
of impacts of existing land uses and projected land uses assuming
full development under existing zoning and land use ordinances in
the drainage area;
[3]
Design stormwater management measures so that the post-construction
peak runoff rates for the two-, ten-, and one-hundred-year storm events
are 50%, 75% and 80%, respectively, of the pre-construction peak runoff
rates. The percentages apply only to the post-construction stormwater
runoff that is attributable to the portion of the site on which the
proposed development or project is to be constructed. The percentages
shall not be applied to post-construction stormwater runoff into tidal
flood hazard areas if the increased volume of stormwater runoff will
not increase flood damages below the point of discharge; or
[4]
In tidal flood hazard areas, stormwater runoff quantity analysis in accordance with Subsection F(1)(c)[1], [2] and [3] above shall only be applied if the increased volume of stormwater runoff could increase flood damages below the point of discharge.
(2)
Any application for a new agricultural development that meets the definition of major development at § 184-14 shall be submitted to the appropriate Soil Conservation District for review and approval in accordance with the requirements of this section and any applicable Soil Conservation District guidelines for stormwater runoff quantity and erosion control. For the purposes of this section, "agricultural development" means land uses normally associated with the production of food, fiber and livestock for sale. Such uses do not include the development of land for the processing or sale of food and the manufacturing of agriculturally related products.
G.
Stormwater runoff quality standards.
(1)
Stormwater management measures shall be designed to reduce the post-construction
load of total suspended solids (TSS) in stormwater runoff by 80% of
the anticipated load from the developed site, expressed as an annual
average. Stormwater management measures shall only be required for
water quality control if an additional 1/4 acre of impervious surface
is being proposed on a development site. The requirement to reduce
TSS does not apply to any stormwater runoff in a discharge regulated
under a numeric effluent limitation for TSS imposed under the New
Jersey Pollution Discharge Elimination System (NJPDES) rules, N.J.A.C.
7:14A, or in a discharge specifically exempt under a NJPDES permit
from this requirement. The water quality design storm is 1.25 inches
of rainfall in two hours. Water quality calculations shall take into
account the distribution of rain from the water quality design storm,
as reflected in Table 1. The calculation of the volume of runoff may
take into account the implementation of nonstructural and structural
stormwater management measures.
|
Table 1: Water Quality Design Storm Distribution
| ||||
|---|---|---|---|---|
|
Time
(minutes)
|
Cumulative Rainfall
(inches)
|
Time
(minutes)
|
Cumulative Rainfall
(inches)
| |
|
0
|
0.0000
|
65
|
0.8917
| |
|
5
|
0.0083
|
70
|
0.9917
| |
|
10
|
0.0166
|
75
|
1.0500
| |
|
15
|
0.0250
|
80
|
1.0840
| |
|
20
|
0.0500
|
85
|
1.1170
| |
|
25
|
0.0750
|
90
|
1.1500
| |
|
30
|
0.1000
|
95
|
1.1750
| |
|
35
|
0.1330
|
100
|
1.2000
| |
|
40
|
0.1660
|
105
|
1.2250
| |
|
45
|
0.2000
|
110
|
1.2334
| |
|
50
|
0.2583
|
115
|
1.2417
| |
|
55
|
0.3583
|
120
|
1.2500
| |
|
60
|
0.6250
| |||
(2)
For purposes of TSS reduction calculations, Table 2 below presents the presumed removal rates for certain BMPs designed in accordance with the New Jersey Stormwater Best Management Practices Manual. The BMP Manual may be obtained from the address identified in § 184-19 or found on the Department's website at www.njstormwater.org. The BMP Manual and other sources of technical guidance are listed in § 184-19. TSS reduction shall be calculated based on the removal rates for the BMPs in Table 2 below. Alternative removal rates and methods of calculating removal rates may be used if the design engineer provides documentation demonstrating the capability of these alternative rates and methods to the review agency. A copy of any approved alternative rate or method of calculating the removal rate shall be provided to the Department at the following address: Division of Watershed Management, New Jersey Department of Environmental Protection, P.O. Box 418, Trenton, New Jersey 08625-0418.
|
Table 2: TSS Removal Rates for BMPs
| ||
|---|---|---|
|
Best Management Practice
|
TSS Percent Removal Rate
| |
|
Bioretention systems
|
90%
| |
|
Constructed stormwater wetland
|
90%
| |
|
Extended detention basin
|
40% to 60%
| |
|
Infiltration structure
|
80%
| |
|
Manufactured treatment device
|
See § 184-18C.
| |
|
Sand filter
|
80%
| |
|
Vegetative filter strip
|
60% to 80%
| |
|
Wet pond
|
50% to 90%
| |
(3)
If more than one BMP in series is necessary to achieve the required
eighty-percent 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; and
| ||
|
B
|
=
|
The TSS percent removal rate applicable to the second BMP.
| ||
(4)
If there is more than one on-site drainage area, the eighty-percent
TSS removal rate shall apply to each drainage area, unless the runoffs
from the subareas converge on site, in which case the removal rate
can be demonstrated through a calculation using a weighted average.
(5)
Stormwater management measures shall also be designed to reduce, to the maximum extent feasible, the post-construction nutrient load of the anticipated load from the developed site in stormwater runoff generated from the water quality design storm. In achieving reduction of nutrients to the maximum extent feasible, the design of the site shall include nonstructural strategies and structural measures that optimize nutrient removal while still achieving the performance standards in § 184-16F and G.
(6)
Additional information and examples are contained in the New Jersey Stormwater Best Management Practices Manual, which may be obtained from the address identified in § 184-19.
(7)
In accordance with the definition of FW1 at N.J.A.C. 7:9B-1.4, stormwater
management measures shall be designed to prevent any increase in stormwater
runoff to waters classified as FW1.
(8)
Special water resource protection areas shall be established along
all waters designated Category One at N.J.A.C. 7:9B, and perennial
or intermittent streams that drain into or upstream of the Category
One waters as shown on the USGS Quadrangle Maps or in the County Soil
Surveys, within the associated HUC14 drainage area. These areas shall
be established for the protection of water quality, aesthetic value,
exceptional ecological significance, exceptional recreational significance,
exceptional water supply significance, and exceptional fisheries significance
of those established Category One waters. These areas shall be designated
and protected as follows:
(a)
The applicant shall preserve and maintain a special water resource
protection area in accordance with one of the following:
[1]
A three-hundred-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.
[2]
Encroachment within the designated special water resource protection area under Subsection G(8)(a)[1] above shall only be allowed where previous development or disturbance has occurred (for example, active agricultural use, parking area or maintained lawn area). The encroachment shall only be allowed where 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. 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.
(b)
All stormwater shall be discharged outside of and flow through
the special water resource protection area and shall comply with the
Standard for Off-Site Stability in the "Standards for Soil Erosion
and Sediment Control in New Jersey," established under the Soil Erosion
and Sediment Control Act, N.J.S.A. 4:24-39 et seq.
(c)
If stormwater discharged outside of and flowing through the
special water resource protection area cannot comply with the Standard
for Off-Site Stability in the "Standards for Soil Erosion and Sediment
Control in New Jersey," established under the Soil Erosion and Sediment
Control Act, N.J.S.A. 4:24-39 et seq., then the stabilization measures
in accordance with the requirements of the above standards may be
placed within the special water resource protection area, provided
that:
[1]
Stabilization measures shall not be placed within 150 feet of
the Category One waterway;
[2]
Stormwater associated with discharges allowed by this section
shall achieve a ninety-five-percent TSS post-construction removal
rate;
[3]
Temperature shall be addressed to ensure no impact on the receiving
waterway;
[4]
The encroachment shall only be allowed where the applicant demonstrates
that the functional value and overall condition of the special water
resource protection area will be maintained to the maximum extent
practicable;
[5]
A conceptual project design meeting shall be held with the appropriate
Department staff and Soil Conservation District staff to identify
necessary stabilization measures; and
[6]
All encroachments proposed under this section shall be subject
to review and approval by the Department.
(d)
A stream corridor protection plan may be developed by a regional stormwater management planning committee as an element of a regional stormwater management plan or by a municipality through an adopted municipal stormwater management plan. If a stream corridor protection plan for a waterway subject to § 184-16G(8) has been approved by the Department of Environmental Protection, then the provisions of the plan shall be the applicable special water resource protection area requirements for that waterway. A stream corridor protection plan for a waterway subject to Subsection G(8) shall maintain or enhance the current functional value and overall condition of the special water resource protection area as defined in Subsection G(8)(a)[1] above. In no case shall a stream corridor protection plan allow the reduction of the special water resource protection area to less than 150 feet as measured perpendicular to the waterway subject to this subsection.
A.
Stormwater runoff shall be calculated in accordance with the following:
(1)
The design engineer shall calculate runoff using one of the following
methods:
(a)
The USDA Natural Resources Conservation Service (NRCS) methodology,
including the NRCS runoff equation and dimensionless unit hydrograph,
as described in the NRCS National Engineering Handbook Section 4 –
Hydrology and Technical Release 55 – Urban Hydrology for Small
Watersheds; or
(b)
The Rational Method for peak flow and the Modified Rational
Method for hydrograph computations.
(2)
For the purpose of calculating runoff coefficients and groundwater recharge, there is a presumption that the pre-construction condition of a site or portion thereof is a wooded land use with good hydrologic condition. The term "runoff coefficient" applies to both the NRCS methodology at § 184-17A(1)(a) and the Rational and Modified Rational Methods at § 184-17A(1)(b). A runoff coefficient or a groundwater recharge land cover for an existing condition may be used on all or a portion of the site if the design engineer verifies that the hydrologic condition has existed on the site or portion of the site for at least five years without interruption prior to the time of application. If more than one land cover have existed on the site during the five years immediately prior to the time of application, the land cover with the lowest runoff potential shall be used for the computations. In addition, there is the presumption that the site is in good hydrologic condition (if the land use type is pasture, lawn, or park), with good cover (if the land use type is woods), or with good hydrologic condition and conservation treatment (if the land use type is cultivation).
(3)
In computing pre-construction stormwater runoff, the design engineer
shall account for all significant land features and structures, such
as ponds, wetlands, depressions, hedgerows, or culverts, that may
reduce pre-construction stormwater runoff rates and volumes.
(4)
In computing stormwater runoff from all design storms, the design
engineer shall consider the relative stormwater runoff rates and/or
volumes of pervious and impervious surfaces separately to accurately
compute the rates and volume of stormwater runoff from the site. To
calculate runoff from unconnected impervious cover, urban impervious
area modifications as described in the NRCS Technical Release 55 –
Urban Hydrology for Small Watersheds and other methods may be employed.
(5)
If the invert of the outlet structure of a stormwater management
measure is below the flood hazard design flood elevation as defined
at N.J.A.C. 7:13, the design engineer shall take into account the
effects of tailwater in the design of structural stormwater management
measures.
B.
Groundwater recharge may be calculated in accordance with the following:
(1)
The New Jersey Geological Survey Report GSR-32, A Method for Evaluating
Ground-Water Recharge Areas in New Jersey, incorporated herein by
reference as amended and supplemented. Information regarding the methodology
is available from the New Jersey Stormwater Best Management Practices
Manual; at http://www.state.nj.us/dep/njgs/; or at New Jersey Geological
Survey, 29 Arctic Parkway, P.O. Box 427, Trenton, New Jersey 08625-0427;
609-984-6587.
A.
Standards for structural stormwater management measures are as follows:
(1)
Structural stormwater management measures shall be designed to take
into account the existing site conditions, including, for example,
environmentally critical areas; wetlands; flood-prone areas; slopes;
depth to seasonal high water table; soil type, permeability and texture;
drainage area and drainage patterns; and the presence of solution-prone
carbonate rocks (limestone).
(2)
Structural stormwater management measures shall be designed to minimize maintenance, facilitate maintenance and repairs, and ensure proper functioning. Trash racks shall be installed at the intake to the outlet structure as appropriate and shall have parallel bars with one-inch spacing between the bars to the elevation of the water quality design storm. For elevations higher than the water quality design storm, the parallel bars at the outlet structure shall be spaced no greater than 1/3 the width of the diameter of the orifice or 1/3 the width of the weir, with a minimum spacing between bars of one inch and a maximum spacing between bars of six inches. In addition, the design of trash racks must comply with the requirements of § 184-20D.
(3)
Structural stormwater management measures shall be designed, constructed,
and installed to be strong, durable, and corrosion resistant. Measures
that are consistent with the relevant portions of the Residential
Site Improvement Standards at N.J.A.C. 5:21-7.3, 5:21-7.4, and 5:21-7.5
shall be deemed to meet this requirement.
(4)
At the intake to the outlet from the stormwater management basin,
the orifice size shall be a minimum of 2 1/2 inches in diameter.
B.
Stormwater management measure guidelines are available in the New Jersey Stormwater Best Management Practices Manual. Other stormwater management measures may be utilized, provided that 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 § 184-16 of this article.
A.
Technical guidance for stormwater management measures can be found in the documents listed at Subsection A(1) and (2) below, which are available from Maps and Publications, New Jersey Department of Environmental Protection, 428 East State Street, P.O. Box 420, Trenton, New Jersey 08625; telephone 609-777-1038.
(1)
Guidelines for stormwater management measures are contained in the
New Jersey Stormwater Best Management Practices Manual, as amended.
Information is provided on stormwater management measures such as
bioretention systems, constructed stormwater wetlands, dry wells,
extended detention basins, infiltration structures, manufactured treatment
devices, pervious paving, sand filters, vegetative filter strips,
and wet ponds.
(2)
The New Jersey Department of Environmental Protection Stormwater
Management Facilities Maintenance Manual, as amended.
B.
Additional technical guidance for stormwater management measures
can be obtained from the following:
(1)
The "Standards for Soil Erosion and Sediment Control in 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.
A.
This section sets forth requirements to protect public safety through
the proper design and operation of stormwater management basins. This
section applies to any new stormwater management basin.
B.
Requirements for trash racks, overflow grates and escape provisions.
(1)
A trash rack is a device designed to catch trash and debris and prevent
the clogging of outlet structures. Trash racks shall be installed
at the intake to the outlet from the stormwater management basin to
ensure proper functioning of the basin outlets in accordance with
the following:
(a)
The trash rack shall have parallel bars, with no greater than
six-inch spacing between the bars.
(b)
The trash rack shall be designed so as not to adversely affect
the hydraulic performance of the outlet pipe or structure.
(c)
The average velocity of flow through a clean trash rack is not
to exceed 2.5 feet per second under the full range of stage and discharge.
Velocity is to be computed on the basis of the net area of opening
through the rack.
(d)
The trash rack shall be constructed and installed to be rigid,
durable, and corrosion resistant and shall be designed to withstand
a perpendicular live loading of 300 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 B(3), "escape provisions" means the permanent installation of ladders, steps, rungs, or other features that provide easily accessible means of egress from stormwater management basins. Stormwater management basins shall include escape provisions as follows:
(a)
If a stormwater management basin has an outlet structure, escape provisions shall be incorporated in or on the structure. With the prior approval of the reviewing agency identified in § 184-20C, 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 feet to six feet in width. One step shall be located approximately 2 1/2 feet below the permanent water surface, and the second step shall be located one foot to 1 1/2 feet above the permanent water surface. See § 184-20D 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. A variance or exemption
from the safety standards for stormwater management basins may be
granted only upon a written finding by the appropriate reviewing agency
(municipality, county or Department) that the variance or exemption
will not constitute a threat to public safety.
D.
Illustration of safety ledges in a new stormwater management basin.
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A.
Submission of site development stormwater plan.
(1)
Whenever an applicant seeks municipal approval of a development subject to this article, the applicant shall submit all of the required components of the checklist for the site development stormwater plan at § 184-21C 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 article.
B.
Site development stormwater plan approval. The applicant's site
development project shall be reviewed as a part of the subdivision
or site plan review process by the municipal board or official from
which municipal approval is sought. That municipal board or official
shall consult the engineer retained by the Planning Board and/or Zoning
Board (as appropriate) to determine if all of the checklist requirements
have been satisfied and to determine if the project meets the standards
set forth in this article.
C.
Checklist requirements.
(1)
The following information shall be required:
(a)
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.
(b)
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.
(c)
Project description and site plan(s). A map (or maps) at the
scale of the topographic 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.
(d)
Land use planning and source control plan. This plan shall provide a demonstration of how the goals and standards of §§ 184-15 through 184-18 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.
(e)
Stormwater management facilities map. The following information,
illustrated on a map of the same scale as the topographic base map,
shall be included:
[1]
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.
[2]
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.
(f)
Calculations.
[1]
Comprehensive hydrologic and hydraulic design calculations for the pre-development and post-development conditions for the design storms specified in § 184-16 of this article.
[2]
When the proposed stormwater management control measures (e.g.,
infiltration basins) depend on the hydrologic properties of soils,
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.
(2)
Waiver from submission requirements. The municipal official or board reviewing an application under this article may, in consultation with the Municipal Engineer, waive submission of any of the requirements in § 184-21C(1)(a) through (f) of this article 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)
The design engineer shall prepare a maintenance plan for the stormwater
management measures incorporated into the design of a major development.
(2)
The maintenance plan shall contain specific preventative maintenance
tasks and schedules; cost estimates, including estimated cost of sediment,
debris, or trash removal; and the name, address, and telephone number
of the person or persons responsible for preventative and corrective
maintenance (including replacement). Maintenance guidelines for stormwater
management measures are available in the New Jersey Stormwater Best
Management Practices Manual. If the maintenance plan identifies a
person other than the developer (for example, a public agency or homeowners'
association) as having the responsibility for maintenance, the plan
shall include documentation of such person's agreement to assume
this responsibility or of the developer's obligation to dedicate
a stormwater management facility to such person under an applicable
ordinance or regulation.
(3)
Responsibility for maintenance shall not be assigned or transferred
to the owner or tenant of an individual property in a residential
development or project, unless such owner or tenant owns or leases
the entire residential development or project.
(4)
If the person responsible for maintenance identified under § 184-22B(2) above is not a public agency, the maintenance plan and any future revisions based on § 184-22B(7) below shall be recorded upon the deed of record for each property on which the maintenance described in the maintenance plan must be undertaken.
(5)
Preventative and corrective maintenance shall be performed to maintain
the function of the stormwater management measure, including repairs
or replacement to the structure; removal of sediment, debris, or trash;
restoration of eroded areas; snow and ice removal; fence repair or
replacement; restoration of vegetation; and repair or replacement
of nonvegetated linings.
(6)
The person responsible for maintenance identified under § 184-22B(2) above shall maintain a detailed log of all preventative and corrective maintenance for the structural stormwater management measures incorporated into the design of the development, including a record of all inspections and copies of all maintenance-related work orders.
(7)
The person responsible for maintenance identified under § 184-22B(2) above shall evaluate the effectiveness of the maintenance plan at least once per year and adjust the plan and the deed as needed.
(8)
The person responsible for maintenance identified under § 184-22B(2) above shall retain and make available, upon request by any public entity with administrative, health, environmental, or safety authority over the site, the maintenance plan and the documentation required by § 184-22B(6) and (7) above.
(9)
The requirements of § 184-22B(3) and (4) do not apply to stormwater management facilities that are dedicated to and accepted by the municipality or another governmental agency.
(10)
In the event that the stormwater management facility becomes
a danger to public safety or public health, or if it is in need of
maintenance or repair, the municipality shall so notify the responsible
person in writing. Upon receipt of that notice, the responsible person
shall have 14 days to effect maintenance and repair of the facility
in a manner that is approved by the Municipal Engineer or his designee.
The municipality, in its discretion, may extend the time allowed for
effecting maintenance and repair for good cause. If the responsible
person fails or refuses to perform such maintenance and repair, the
municipality or the county may immediately proceed to do so and shall
bill the cost thereof to the responsible person.
C.
Nothing in this section shall preclude the municipality in which
the major development is located from requiring the posting of a performance
or maintenance guarantee in accordance with N.J.S.A. 40:55D-53.
This article 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 article 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 article.
