A.
To the maximum extent practicable, the standards in §§ 296-10 and 296-11 shall be met by incorporating nonstructural stormwater management strategies set forth in this section into the design. The applicant shall identify the nonstructural measures incorporated into the design of the project. Documentation of the use of nonstructural stormwater management measures shall require the preparation by the applicant of the NJDEP low-impact development checklist. If the applicant contends that it is not feasible for engineering, environmental, or safety reasons to incorporate any or only specific nonstructural stormwater management measures identified in Subsection B below into the design of a particular project, the applicant shall identify the strategy or strategies considered and provide a basis for the contention. In both cases, the applicant bears the burden of proving any impracticability.
B.
Nonstructural stormwater management strategies incorporated
into site design shall:
(1)
Protect areas that provide water quality benefits or
areas particularly susceptible to erosion and sediment loss;
(2)
Minimize the creation of new impervious surfaces and
reduce, break up or otherwise disconnect the flow of runoff over impervious
surfaces;
(3)
Maximize the protection of natural drainage features
and vegetation, except where native or natural vegetation is considered invasive;
(4)
Minimize the decrease in the time of concentration from
pre-construction to post-construction;
(5)
Minimize land clearing and disturbance and overall site
grading;
(6)
Minimize soil compaction;
(7)
Retain native, noninvasive vegetation, plant low-maintenance
landscaping, plant native vegetation, and minimize the creation of lawns and
the use of plantings and vegetation that require the excessive use of fertilizers,
pesticides and irrigation;
(8)
Provide vegetated open-channel conveyance systems discharging
into and through stable vegetated areas;
(9)
Provide other source controls to prevent or minimize
the use, exposure and/or mobilization of pollutants and prevent or minimize
the release and transport of those pollutants into stormwater runoff. Such
source controls include, but are not limited to:
(a)
Site design features that help to prevent accumulation of trash and debris in drainage systems, including features that satisfy Subsection C below;
(b)
Site design features that help to prevent discharge of
trash and debris from drainage systems;
(c)
Site design features that help to prevent and/or contain
spills or other harmful accumulations of pollutants at industrial or commercial
developments; and
(d)
When establishing vegetation after land disturbance,
application of 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. Prior to applying fertilizer, soil tests must be conducted
on site to determine the type of fertilization necessary.
C.
Site design features identified under Subsection B(9)(b) above shall comply with the following standard to control passage of solid and floatable materials through storm drain inlets. For exemptions to this standard see Subsection C(3) below.
(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 inches across the smallest dimension.
(2)
Whenever design engineers use a curb-opening inlet, the
clear space in that curb opening (or each individual clear space, if the curb
opening has two or more clear spaces) shall have an area of no more than seven
square inches or be no greater than two inches across the smallest dimension.
(3)
This standard does not apply:
(a)
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;
(b)
Where flows from the water quality design storm as specified in § 296-11A 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:
(c)
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 § 296-11A; or
(d)
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.
D.
Any land area used as a nonstructural stormwater management measure to meet the performance standards in §§ 296-10 and 296-11 shall be:
(1)
Dedicated to a government agency;
(2)
Subjected to a conservation restriction filed with the
Hunterdon County Clerk's office; or
(3)
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.
This section contains minimum design and performance standards to control
erosion, maintain groundwater recharge, and control stormwater runoff quantity
impacts of major development projects.
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)
Using the criteria for calculating stormwater runoff and groundwater recharge in § 296-17, the design engineer shall comply with at least one of the following standards:
(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 projected stormwater runoff volume
produced by the two-year, twenty-four-hour storm from pre-developed to post-developed
conditions is fully infiltrated.
(2)
Groundwater recharge is not required at major development projects located within an urban redevelopment area as defined in § 296-2 or from those portions of major development projects that produce stormwater runoff described in Subsection B(3)(a)[3] below.
(3)
The following two types of stormwater runoff shall not
be recharged:
(a)
Stormwater runoff from areas of high pollutant loading.
High pollutant loading areas are:
[1]
Areas in industrial and commercial developments where
solvents and/or petroleum products are loaded/unloaded, stored, or applied;
[2]
Areas where pesticides are loaded/unloaded or stored;
[3]
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; and
[4]
Areas where recharge would be inconsistent with a Department-approved
remedial action work plan or landfill closure plan and areas with high risks
for spills of toxic materials, such as gas stations and vehicle maintenance
facilities; and
(b)
Stormwater runoff from industrial areas exposed to source
material.
(4)
The design engineer shall assess and certify 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 facilities,
and interference with the proper operation of subsurface sewage disposal systems
and other subsurface structures in the vicinity of a groundwater recharge
measure.
C.
The minimum design and performance standards for the
control of stormwater runoff quantity are as follows:
(1)
Using the criteria for calculating stormwater runoff and groundwater recharge in Article IV, the design engineer shall comply with at least one of the following standards:
(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 these 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.[1]
(c)
Design on-site stormwater management measures so 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. Peak stormwater
outflow rates 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. The 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:
(2)
Any application for a new agricultural or horticultural development that meets the definition of major development in § 296-6 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.
A.
Stormwater management measures shall be designed to reduce by 80% the anticipated post-construction load of total suspended solids (TSS) in stormwater runoff from the developed site, expressed as pounds per year. Stormwater management measures shall also be in conformance with § 296-11I(3) of this chapter. Stormwater management measures shall only be required for water quality control if an additional 1/4 acre or more 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. Daily limits of TSS (TMDL) may apply to the site development based on conditions of regulatory approvals.
B.
The water quality design storm shall be 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 below, subject to revision due to subsequent rule changes. 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
| |||
C.
For purposes of TSS reduction calculations, Table 2 below presents the presumed removal rates for certain BMPs designed, constructed and maintained in accordance with the New Jersey Stormwater Best Management Practices Manual, subject to revision due to subsequent rule changes. The current edition of the BMP Manual may be obtained from the address identified in Article VII or found on the Department's Web site at www.njstormwater.org. The BMP Manual and other sources of technical guidance are listed in Article VII. TSS reduction shall be calculated based on the removal rates for the BMPs in Table 2 below. Alternative BMPs, removal rates and methods of calculating removal rates may be approved if the design engineer provides documentation demonstrating the capability of these alternative BMPs, removal rates and computational methods to the review agency. Documentation for alternative rates and methods shall consist of a published (peer-reviewed) journal article or scientific paper. A copy of any approved alternative rate or method of calculating the removal rate, including documentation, shall be provided to the Department at the following address: Division of Watershed Management, New Jersey Department of Environmental Protection, PO Box 418 Trenton, New Jersey 08625-0418.
D.
TSS reduction calculation.
(1)
If more than one BMP in series is necessary to achieve
the required TSS reduction of 80% for a site, the applicant shall utilize
the following formula to calculate TSS reduction:
|
R = A + B - (AXB)/100
| ||||
|
Where
| ||||
|
R
|
=
|
Total TSS percent load removal (expressed as a whole number) from application
of both BMPs
| ||
|
A
|
=
|
TSS percent removal rate (whole number) applicable to the first (upstream)
BMP
| ||
|
B
|
=
|
TSS percent removal rate (whole number) applicable to the second (downstream)
BMP
| ||
(2)
In cases where three (or more) BMPs are used in series,
the applicant shall calculate the TSS reduction for the two most upstream
BMPs in the series using the above formula, then substitute the result (R)
of that calculation in the formula for "A" when calculating the combined result
with the next BMP in the series.
|
Table 2
TSS Removal Rates for BMPs
(Source: New Jersey Stormwater Best Management Practices Manual)
| ||
|---|---|---|
|
Best Management Practices
|
TSS Percent Removal Rate
| |
|
Bioretention systems
|
90%
| |
|
Wetland
|
90%
| |
|
Extended detention basin
|
40% - 60%
| |
|
Infiltration structure
|
80%
| |
|
Manufactured treatment device
|
See § 296-20.
| |
|
Sand filter
|
80%
| |
|
Vegetative filter strip
|
60% - 80%
| |
|
Wet pond
|
50% - 90%
| |
E.
If there is more than one on-site drainage area, the
TSS removal rate of 80% shall apply to the discharge of each drainage subarea,
unless the runoff from the subareas converge on site, in which case the removal
rate can be demonstrated through a calculation using an area-weighted average.
F.
Stormwater management measures shall also be designed to reduce, to the maximum extent practicable, the post-construction nutrient load from the developed site in stormwater runoff generated from the water quality design storm. In achieving reduction of nutrients to the maximum extent practicable, the design of the site shall include nonstructural strategies and structural measures that optimize nutrient removal while still achieving the performance standards in §§ 296-10 and 296-11. This standard may be superseded by a more stringent numeric effluent limitation 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. Daily limits for nutrient loading (TMDL) may apply to the site development based on conditions of regulatory approvals.
G.
Additional information and examples are contained in the New Jersey Stormwater Best Management Practices Manual, which may be obtained from the address identified in Article VII.
H.
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 and any new stormwater discharge point to waters
classified as FW1.
I.
Special water resource protection areas shall be established
along all waters designated Category One at N.J.A.C. 7:9B, and along all 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 HUC-14 drainage area. Other authoritative sources of stream
delineation may be utilized, such as a delineation that is part of the municipal
or regional stormwater management plan or a stream delineation overlay prepared
by the Department. These areas shall be designated and protected as follows:
(1)
The applicant shall preserve and maintain a special water
resource protection area in accordance with one of the following, unless superseded
by a local Stream Corridor Protection Ordinance:
(a)
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.
(b)
Encroachment within the designated special water resource protection area under Subsection I(1)(a) above shall only be allowed where previous development or disturbance has occurred (for example, preexisting active agricultural use, parking area or maintained lawn area). The encroachment shall only be allowed where the applicant demonstrates to the satisfaction of the review agency that the functional value and overall condition of the special water resource protection area will be maintained to the maximum extent practicable. In no case shall the remaining special water resource protection area be reduced to less than 150 feet as measured perpendicular to the top of bank of the waterway or center line of the waterway where the bank is undefined. All encroachments proposed under this subsection shall be subject to review and approval by the Department.
(2)
All stormwater shall be discharged outside of and flow
through the special water resource protection area and shall comply with the
Standard for Off-Site Stability in the "Standards for Soil Erosion and Sediment
Control in New Jersey," established under the Soil Erosion and Sediment Control
Act, N.J.S.A. 4:24-39 et seq.
(3)
If stormwater discharged outside of and flowing through
the special water resource protection area cannot comply with the Standard
For Off-Site Stability in the "Standards for Soil Erosion and Sediment Control
in New Jersey," established under the Soil Erosion and Sediment Control Act,
N.J.S.A. 4:24-39 et seq., then the stabilization measures in accordance with
the requirements of the above standards may be placed within the special water
resource protection area, provided that:
(a)
Stabilization measures shall not be placed within 150
feet of the Category One waterway;
(b)
Stormwater discharges allowed by this section shall achieve
a TSS post-construction removal rate of 95%;
(c)
Thermal pollution by stormwater discharges shall be addressed
to ensure no significant increase or decrease in temperature occurs in the
receiving waterway outside of the mixing zone;
(d)
The encroachment shall only be allowed where the applicant
demonstrates to the satisfaction of the review agency that the ecological
value and condition of the special water resource protection area will be
maintained to the maximum extent practicable;
(e)
A conceptual project design meeting shall be held with
the appropriate Department staff and Soil Conservation District staff to identify
necessary stabilization measures; and
(f)
All encroachments proposed under this section shall be
reviewed and approved by the Department prior to approval by the review agency.
(4)
A stream corridor protection plan for a waterway subject to Subsection I shall maintain or enhance the current ecological value and condition of the special water resource protection area as defined in Subsection I(1)(a) 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.
(5)
Subsection I does not apply to the construction of one individual single-family dwelling that is not part of a larger development and is on a lot receiving preliminary or final subdivision approval on or before February 2, 2004, provided that the construction begins on or before February 2, 2009.
The development shall incorporate a maintenance plan for the stormwater management measures incorporated into the design of a major development in accordance with Article X.
The following linear development projects are exempt from the groundwater recharge, stormwater runoff quantity, and stormwater runoff quality requirements of §§ 296-10 and 296-11:
A.
A waiver from strict compliance with the groundwater recharge, stormwater runoff quantity, and stormwater runoff quality requirements of §§ 296-10 and 296-11 may be obtained for the enlargement of an existing public roadway or railroad; or the construction or enlargement of a public pedestrian access, provided that the following conditions are met:
(1)
The applicant demonstrates that there is a public need
for the project that cannot be accomplished by any other means;
(2)
The applicant demonstrates, through an alternatives analysis acceptable to the review agency, that through the use of nonstructural and structural stormwater management strategies and measures, the option selected complies with the requirements of §§ 296-10 and 296-11 to the maximum extent practicable;
(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 A(3) above within the upstream drainage area of the receiving stream, that would provide additional opportunities to mitigate the requirements of §§ 296-10 and 296-11 that were not achievable on site.
B.
A waiver from strict compliance with the requirements of §§ 296-10 and 296-11 may be issued in those cases where an applicant has demonstrated the inability or impracticality of strict compliance, other than projects addressed under Subsection A, 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 strict as N.J.A.C. 7:8. A waiver from strict compliance for such projects can only be obtained if the applicant agrees to undertake a suitable mitigation measure identified in the mitigation section of the municipality's stormwater management plan. In such cases, the applicant must submit a mitigation plan detailing how the project's failure to strictly comply will be compensated. In cases where a waiver is granted, an applicant should provide mitigation, if possible and/or practical, within the same HUC-14 watershed within which the subject project is proposed, or contribute funding toward a regional stormwater control project, or provide for equivalent treatment at an alternate location, or other equivalent water quality benefit, in lieu of implementing the required stormwater control measures on their specific site.
When habitat for threatened and endangered species (See definition for "environmental critical areas" in § 296-6.), is present on a site, stormwater management measures shall be implemented to avoid adverse impacts caused by pollutant discharge, the creation of concentrated flow, or the alteration of recharge.
