For the purpose of this chapter, the following terms, phrases,
words and their derivations shall have the meanings stated herein
unless their use in the text of this chapter clearly demonstrates
a different meaning. When not inconsistent with the context, words
used in the present tense include the future, words used in the plural
number include the singular number, and words used in the singular
number include the plural number. The word "shall" is always mandatory
and not merely directory. The definitions below are the same as or
based on the corresponding definitions in the Stormwater Management
Rules at N.J.A.C. 7:8-1.2.
COMMUNITY BASIN
An infiltration system, sand filter designed to infiltrate,
standard constructed wetland, or wet pond, established in accordance
with N.J.A.C. 7:8-4.2(c)14, that is designed and constructed in accordance
with the New Jersey Stormwater Best Management Practices Manual, or
an alternate design, approved in accordance with N.J.A.C. 7:8-5.2(g),
for an infiltration system, sand filter designed to infiltrate, standard
constructed wetland, or wet pond and that complies with the requirements
of this chapter.
CONTRIBUTORY DRAINAGE AREA
The area from which stormwater runoff drains to a stormwater
management measure, not including the area of the stormwater management
measure itself.
CORE
A pedestrian-oriented area of commercial and civic uses serving
the surrounding municipality, generally including housing and access
to public transportation.
COUNTY REVIEW AGENCY
An agency designated by the Sussex County Board of County
Commissioners to review municipal stormwater management plans and
implementing ordinance(s). The county review agency may either be:
A.
A county planning agency; or
B.
A county water resource association created under N.J.S.A. 58:16A-55.5,
if the ordinance or resolution delegates authority to approve, conditionally
approve, or disapprove municipal stormwater management plans and implementing
ordinances.
DEPARTMENT
The Department of Environmental Protection.
DESIGN ENGINEER
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.
DESIGNATED CENTER
A State Development and Redevelopment Plan Center as designated
by the State Planning Commission such as urban, regional, town, village,
or hamlet.
DEVELOPMENT
The division of a parcel of land into two or more parcels,
the construction, reconstruction, conversion, structural alteration,
relocation or enlargement of any building or structure, any mining
excavation or landfill, and any use or change in the use of any building
or other structure, or land or extension of use of land, for which
permission is required under the Municipal Land Use Law, N.J.S.A.
40:55D-1 et seq. In the case of development of agricultural land, "development"
means any activity that requires a state permit, any activity reviewed
by the County Agricultural Board (CAB) and the State Agricultural
Development Committee (SADC), and municipal review of any activity
not exempted by the Right to Farm Act, N.J.S.A. 4:1C-1 et seq.
DISTURBANCE
The placement or reconstruction of impervious surface or
motor vehicle surface, or exposure and/or movement of soil or bedrock
or clearing, cutting, or removing of vegetation. Milling and repaving
is not considered disturbance for the purposes of this definition.
DRAINAGE AREA
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.
ENVIRONMENTALLY CONSTRAINED AREA
The following areas where the physical alteration of the
land is in some way restricted, either through regulation, easement,
deed restriction or ownership such as wetlands, floodplains, threatened
and endangered species sites or designated habitats, and parks and
preserves. Habitats of endangered or threatened species are identified
using the Department's Landscape Project as approved by the Department's
Endangered and Nongame Species Program.
ENVIRONMENTALLY CRITICAL AREA
An area or feature which is of significant environmental
value, including but not limited to stream corridors, natural heritage
priority sites, habitats of endangered or threatened species, large
areas of contiguous open space or upland forest, steep slopes, and
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.
EROSION
The detachment and movement of soil or rock fragments by
water, wind, ice, or gravity.
GREEN INFRASTRUCTURE
A stormwater management measure that manages stormwater close
to its source by:
A.
Treating stormwater runoff through infiltration into subsoil;
B.
Treating stormwater runoff through filtration by vegetation
or soil; or
C.
Storing stormwater runoff for reuse.
HUC 14 or HYDROLOGIC UNIT CODE 14
An area within which water drains to a particular receiving
surface water body, also known as a "subwatershed," which is identified
by a fourteen-digit hydrologic unit boundary designation, delineated
within New Jersey by the United States Geological Survey.
IMPERVIOUS SURFACE
A surface that has been covered with a layer of material
so that it is highly resistant to infiltration by water.
INFILTRATION
The process by which water seeps into the soil from precipitation.
LEAD PLANNING AGENCY
One or more public entities having stormwater management
planning authority designated by the regional stormwater management
planning committee pursuant to N.J.A.C. 7:8-3.2, that serves as the
primary representative of the committee.
MAJOR DEVELOPMENT
An individual development, as well as multiple developments
that individually or collectively result in the disturbance of one
or more acres of land since February 2, 2004. Major development includes
all developments that are part of a common plan of development or
sale (for example, phased residential development) that collectively
or individually result in the disturbance of one or more acres of
land since February 2, 2004. Projects undertaken by any government
agency that otherwise meet the definition of "major development" but
which do not require approval under the Municipal Land Use Law, N.J.S.A.
40:55D-1 et seq., are also considered major development.
MOTOR VEHICLE
Land vehicles propelled other than by muscular power, such
as automobiles, motorcycles, autocycles, and low-speed vehicles. For
the purposes of this definition, motor vehicle does not include farm
equipment, snowmobiles, all-terrain vehicles, motorized wheelchairs,
go-carts, gas buggies, golf carts, ski-slope-grooming machines, or
vehicles that run only on rails or tracks.
MOTOR VEHICLE SURFACE
Any pervious or impervious surface that is intended to be
used by motor vehicles and/or aircraft, and is directly exposed to
precipitation including, but not limited to, driveways, parking areas,
parking garages, roads, racetracks, and runways.
NEW JERSEY STORMWATER BEST MANAGEMENT PRACTICES (BMP) MANUAL
or BMP MANUAL
The manual maintained by the Department providing, in part, design specifications, removal rates, calculation methods, and soil testing procedures approved by the Department as being capable of contributing to the achievement of the stormwater management standards specified in this chapter. The BMP Manual is periodically amended by the Department as necessary to provide design specifications on additional best management practices and new information on already included practices reflecting the best available current information regarding the particular practice and the Department's determination as to the ability of that best management practice to contribute to compliance with the standards contained in this chapter. Alternative stormwater management measures, removal rates, or calculation methods may be utilized, subject to any limitations specified in this chapter, provided the design engineer demonstrates to the municipality, in accordance with §
150-4F of this chapter and N.J.A.C. 7:8-5.2(g), that the proposed measure and its design will contribute to achievement of the design and performance standards established by this chapter.
NODE
An area designated by the State Planning Commission concentrating
facilities and activities which are not organized in a compact form.
NUTRIENT
A chemical element or compound, such as nitrogen or phosphorus,
which is essential to and promotes the development of organisms.
PERSON
Any individual, corporation, company, partnership, firm,
association, political subdivision of this state and any state, interstate
or federal agency.
POLLUTANT
Any dredged spoil, solid waste, incinerator residue, filter
backwash, sewage, garbage, refuse, oil, grease, sewage sludge, munitions,
chemical wastes, biological materials, medical wastes, radioactive
substance [except those regulated under the Atomic Energy Act of 1954,
as amended (42 U.S.C. § 2011 et seq.)], thermal waste, wrecked
or discarded equipment, rock, sand, cellar dirt, industrial, municipal,
agricultural, and construction waste or runoff, or other residue discharged
directly or indirectly to the land, groundwaters or surface waters
of the state, or to a domestic treatment works. "Pollutant" includes
both hazardous and nonhazardous pollutants.
RECHARGE
The amount of water from precipitation that infiltrates into
the ground and is not evapotranspired.
REGULATED IMPERVIOUS SURFACE
Any of the following, alone or in combination:
A.
A net increase of impervious surface;
B.
The total area of impervious surface collected by a new stormwater
conveyance system (for the purpose of this definition, a "new stormwater
conveyance system" is a stormwater conveyance system that is constructed
where one did not exist immediately prior to its construction or an
existing system for which a new discharge location is created);
C.
The total area of impervious surface proposed to be newly collected
by an existing stormwater conveyance system; and/or
D.
The total area of impervious surface collected by an existing
stormwater conveyance system where the capacity of that conveyance
system is increased.
REGULATED MOTOR VEHICLE SURFACE
Any of the following, alone or in combination:
A.
The total area of motor vehicle surface that is currently receiving
water;
B.
A net increase in motor vehicle surface; and/or quality treatment
either by vegetation or soil, by an existing stormwater management
measure, or by treatment at a wastewater treatment plant, where the
water quality treatment will be modified or removed.
SEDIMENT
Solid material, mineral or organic, that is in suspension,
is being transported, or has been moved from its site of origin by
air, water or gravity as a product of erosion.
SITE
The lot or lots upon which a major development is to occur
or has occurred.
SOIL
All unconsolidated mineral and organic material of any origin.
STATE PLAN POLICY MAP
The geographic application of the State Development and Redevelopment
Plan's goals and statewide policies, and the official map of
these goals and policies.
STORMWATER
Water resulting from precipitation (including rain and snow)
that runs off the land's surface, is transmitted to the subsurface,
or is captured by separate storm sewers or other sewage or drainage
facilities, or conveyed by snow removal equipment.
STORMWATER MANAGEMENT BMP
An excavation or embankment and related areas designed to
retain stormwater runoff. A stormwater management BMP may either be
normally dry (that is, a detention basin or infiltration system),
retain water in a permanent pool (a retention basin), or be planted
mainly with wetland vegetation (most constructed stormwater wetlands).
STORMWATER MANAGEMENT MEASURE
Any practice, technology, process, program, or other method
intended to control or reduce stormwater runoff and associated pollutants,
or to induce or control the infiltration or groundwater recharge of
stormwater or to eliminate illicit or illegal nonstormwater discharges
into stormwater conveyances.
STORMWATER MANAGEMENT PLANNING AREA
The geographic area for which a stormwater management planning
agency is authorized to prepare stormwater management plans, or a
specific portion of that area identified in a stormwater management
plan prepared by that agency.
STORMWATER RUNOFF
Water flow on the surface of the ground or in storm sewers,
resulting from precipitation.
WATER CONTROL STRUCTURE
A structure within, or adjacent to, a water, which intentionally
or coincidentally alters the hydraulic capacity, the flood elevation
resulting from the two-, ten-, or 100-year storm, flood hazard area
limit, and/or floodway limit of the water. Examples of a water control
structure may include a bridge, culvert, dam, embankment, ford (if
above grade), retaining wall, and weir.
WATERS OF THE STATE
The ocean and its estuaries, all springs, streams, wetlands,
and bodies of surface or groundwater, whether natural or artificial,
within the boundaries of the State of New Jersey or subject to its
jurisdiction.
WETLANDS or WETLAND
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."
This section specifies the types of green infrastructure BMPs
that may be used to satisfy the groundwater recharge, stormwater runoff
quality, and stormwater runoff quantity standards.
A. To satisfy the groundwater recharge and stormwater runoff quality standards at §§
150-6 and
150-7, the design engineer shall utilize green infrastructure BMPs identified in Table 1 at §
150-4F and/or an alternative stormwater management measure approved in accordance with §
150-4G. The following green infrastructure BMPs are subject to the following maximum contributory drainage area limitations:
Best Management Practice
|
Maximum Contributory Drainage Area
|
---|
Dry well
|
1 acre
|
Manufactured treatment device
|
2.5 acres
|
Pervious pavement systems
|
Area of additional inflow cannot exceed three times the area
occupied by the BMP
|
Small-scale bioretention systems
|
2.5 acres
|
Small-scale infiltration basin
|
2.5 acres
|
Small-scale sand filter
|
2.5 acres
|
B. To satisfy the stormwater runoff quantity standards at §
150-8, the design engineer shall utilize BMPs from Table 1 or from Table 2 and/or an alternative stormwater management measure approved in accordance with §
150-4G.
C. If a variance in accordance with N.J.A.C. 7:8-4.6 or a waiver from strict compliance in accordance with §
150-4D is granted from the requirements of this section, then BMPs from Table 1, 2, or 3, and/or an alternative stormwater management measure approved in accordance with §
150-4G, may be used to meet the groundwater recharge, stormwater runoff quality, and stormwater runoff quantity standards at §§
150-6,
150-7, and
150-8.
D. For separate or combined storm sewer improvement projects, such as sewer separation, undertaken by a government agency or public utility (for example, a sewerage company), the requirements of this section shall only apply to areas owned in fee simple by the government agency or utility, and areas within a right-of-way or easement held or controlled by the government agency or utility; the entity shall not be required to obtain additional property or property rights to fully satisfy the requirements of this section. Regardless of the amount of area of a separate or combined storm sewer improvement project subject to the green infrastructure requirements of this section, each project shall fully comply with the applicable groundwater recharge, stormwater runoff quality control, and stormwater runoff quantity standards at §§
150-6,
150-7, and
150-8, unless the project is granted a waiver from strict compliance in accordance with §
150-4D.
This section contains the minimum design and performance standards
for groundwater recharge as follows:
A. The design engineer shall, using the assumptions and factors for stormwater runoff and groundwater recharge calculations at §
150-9, either:
(1) Demonstrate through hydrologic and hydraulic analysis that the site
and its stormwater management measures maintain 100% of the average
annual preconstruction groundwater recharge volume for the site; or
(2) Demonstrate through hydrologic and hydraulic analysis that the increase
of stormwater runoff volume from preconstruction to post-construction
for the two-year storm is infiltrated.
B. This groundwater recharge requirement does not apply to projects within the urban redevelopment area, or to projects subject to Subsection
C below.
C. The following types of stormwater shall not be recharged:
(1) Stormwater from areas of high pollutant loading. High pollutant loading
areas are areas in industrial and commercial developments where solvents
and/or petroleum products are loaded/unloaded, stored, or applied,
areas where pesticides are loaded/unloaded or stored; areas where
hazardous materials are expected to be present in greater than "reportable
quantities" as defined by the United States Environmental Protection
Agency (EPA) at 40 CFR 302.4; areas where recharge would be inconsistent
with Department-approved remedial action work plan or landfill closure
plan and areas with high risks for spills of toxic materials, such
as gas stations and vehicle maintenance facilities; and
(2) Industrial stormwater exposed to source material. "Source material"
means any material(s) or machinery, located at an industrial facility,
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.
This section contains the minimum design and performance standards
to control stormwater runoff quality impacts of major development.
Stormwater runoff quality standards are applicable when the major
development results in an increase of 1/4 acre or more of regulated
motor vehicle surface.
A. Stormwater management measures shall be designed to reduce the post-construction
load of total suspended solids (TSS) in stormwater runoff generated
from the water quality design storm as follows:
(1) Eighty percent TSS removal of the anticipated load, expressed as
an annual average shall be achieved for the stormwater runoff from
the net increase of motor vehicle surface.
(2) If the surface is considered regulated motor vehicle surface because
the water quality treatment for an area of motor vehicle surface that
is currently receiving water quality treatment either by vegetation
or soil, by an existing stormwater management measure, or by treatment
at a wastewater treatment plant is to be modified or removed, the
project shall maintain or increase the existing TSS removal of the
anticipated load expressed as an annual average.
B. The requirement to reduce TSS does not apply to any stormwater runoff in a discharge regulated under a numeric effluent limitation for TSS imposed under the New Jersey Pollutant Discharge Elimination System (NJPDES) rules, N.J.A.C. 7:14A, or in a discharge specifically exempt under a NJPDES permit from this requirement. Every major development, including any that discharge into a combined sewer system, shall comply with Subsection
A above, unless the major development is itself subject to a NJPDES permit with a numeric effluent limitation for TSS or the NJPDES permit to which the major development is subject exempts the development from a numeric effluent limitation for TSS.
C. 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
4, below. The calculation of the volume of runoff may take into account
the implementation of stormwater management measures.
Table 4
|
---|
Water Quality Design Storm Distribution
|
---|
Time
(minutes)
|
Cumulative Rainfall
(inches)
|
Time
(minutes)
|
Cumulative Rainfall
(inches)
|
Time
(minutes)
|
Cumulative Rainfall
(inches)
|
---|
1
|
0.00166
|
41
|
0.1728
|
81
|
1.0906
|
2
|
0.00332
|
42
|
0.1796
|
82
|
1.0972
|
3
|
0.00498
|
43
|
0.1864
|
83
|
1.1038
|
4
|
0.00664
|
44
|
0.1932
|
84
|
1.1104
|
5
|
0.00830
|
45
|
0.2000
|
85
|
1.1170
|
6
|
0.00996
|
46
|
0.2117
|
86
|
1.1236
|
7
|
0.01162
|
47
|
0.2233
|
87
|
1.1302
|
8
|
0.01328
|
48
|
0.2350
|
88
|
1.1368
|
9
|
0.01494
|
49
|
0.2466
|
89
|
1.1434
|
10
|
0.01660
|
50
|
0.2583
|
90
|
1.1500
|
11
|
0.01828
|
51
|
0.2783
|
91
|
1.1550
|
12
|
0.01996
|
52
|
0.2983
|
92
|
1.1600
|
13
|
0.02164
|
53
|
0.3183
|
93
|
1.1650
|
14
|
0.02332
|
54
|
0.3383
|
94
|
1.1700
|
15
|
0.02500
|
55
|
0.3583
|
95
|
1.1750
|
16
|
0.03000
|
56
|
0.4116
|
96
|
1.1800
|
17
|
0.03500
|
57
|
0.4650
|
97
|
1.1850
|
18
|
0.04000
|
58
|
0.5183
|
98
|
1.1900
|
19
|
0.04500
|
59
|
0.5717
|
99
|
1.1950
|
20
|
0.05000
|
60
|
0.6250
|
100
|
1.2000
|
21
|
0.05500
|
61
|
0.6783
|
101
|
1.2050
|
22
|
0.06000
|
62
|
0.7317
|
102
|
1.2100
|
23
|
0.06500
|
63
|
0.7850
|
103
|
1.2150
|
24
|
0.07000
|
64
|
0.8384
|
104
|
1.2200
|
25
|
0.07500
|
65
|
0.8917
|
105
|
1.2250
|
26
|
0.08000
|
66
|
0.9117
|
106
|
1.2267
|
27
|
0.08500
|
67
|
0.9317
|
107
|
1.2284
|
28
|
0.09000
|
68
|
0.9517
|
108
|
1.2300
|
29
|
0.09500
|
69
|
0.9717
|
109
|
1.2317
|
30
|
0.10000
|
70
|
0.9917
|
110
|
1.2334
|
31
|
0.10660
|
71
|
1.0034
|
111
|
1.2351
|
32
|
0.11320
|
72
|
1.0150
|
112
|
1.2367
|
33
|
0.11980
|
73
|
1.0267
|
113
|
1.2384
|
34
|
0.12640
|
74
|
1.0383
|
114
|
1.2400
|
35
|
0.13300
|
75
|
1.0500
|
115
|
1.2417
|
36
|
0.13960
|
76
|
1.0568
|
116
|
1.2434
|
37
|
0.14620
|
77
|
1.0636
|
117
|
1.2450
|
38
|
0.15280
|
78
|
1.0704
|
118
|
1.2467
|
39
|
0.15940
|
79
|
1.0772
|
119
|
1.2483
|
40
|
0.16600
|
80
|
1.0840
|
120
|
1.2500
|
D. If more than one BMP in series is necessary to achieve the required
80% TSS reduction for a site, the applicant shall utilize the following
formula to calculate TSS reduction:
Where:
|
R
|
=
|
Total TSS percent load removal from application of both BMPs.
|
A
|
=
|
The TSS percent removal rate applicable to the first BMP.
|
B
|
=
|
The TSS percent removal rate applicable to the second BMP.
|
E. Stormwater management measures shall also be designed to reduce, to the maximum extent feasible, the post-construction nutrient load of the anticipated load from the developed site in stormwater runoff generated from the water quality design storm. In achieving reduction of nutrients to the maximum extent feasible, the design of the site shall include green infrastructure BMPs that optimize nutrient removal while still achieving the performance standards in §§
150-6,
150-7, and
150-8.
F. In accordance with the definition of FW1 at N.J.A.C. 7:9B-1.4, stormwater
management measures shall be designed to prevent any increase in stormwater
runoff to waters classified as FW1.
G. The Flood Hazard Area Control Act Rules at N.J.A.C. 7:13-4.1(c)1
establish 300-foot riparian zones along Category One waters, as designated
in the surface water quality standards at N.J.A.C. 7:9B, and certain
upstream tributaries to Category One waters. A person shall not undertake
a major development that is located within or discharges into a 300-foot
riparian zone without prior authorization from the Department under
N.J.A.C. 7:13.
H. Pursuant to the Flood Hazard Area Control Act Rules at N.J.A.C. 7:13-11.2(j)3i,
runoff from the water quality design storm that is discharged within
a 300-foot riparian zone shall be treated in accordance with this
section to reduce the post-construction load of total suspended solids
by 95% of the anticipated load from the developed site, expressed
as an annual average.
I. This stormwater runoff quality standards do not apply to the construction
of one individual single-family dwelling, provided that it is not
part of a larger development or subdivision that has received preliminary
or final site plan approval prior to December 3, 2018, and that the
motor vehicle surfaces are made of permeable material(s) such as gravel,
dirt, and/or shells.
This section contains the minimum design and performance standards
to control stormwater runoff quantity impacts of major development.
A. In order to control stormwater runoff quantity impacts, the design engineer shall, using the assumptions and factors for stormwater runoff calculations at §
150-9, 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 100-year storm events do not exceed, at any point in time,
the preconstruction runoff hydrographs for the same storm events;
(2) Demonstrate through hydrologic and hydraulic analysis that there
is no increase, as compared to the preconstruction condition, in the
peak runoff rates of stormwater leaving the site for the two-, ten-
and 100-year storm events and that the increased volume or change
in timing of stormwater runoff will not increase flood damage at or
downstream of the site. This analysis shall include the analysis of
impacts of existing land uses and projected land uses assuming full
development under existing zoning and land use ordinances in the drainage
area;
(3) Design stormwater management measures so that the post-construction
peak runoff rates for the two-, ten- and 100-year storm events are
50%, 75% and 80%, respectively, of the preconstruction peak runoff
rates. The percentages apply only to the post-construction stormwater
runoff that is attributable to the portion of the site on which the
proposed development or project is to be constructed; or
(4) In tidal flood hazard areas, stormwater runoff quantity analysis in accordance with Subsection
A(1),
(2), and
(3) above is required unless the design engineer demonstrates through hydrologic and hydraulic analysis that the increased volume, change in timing, or increased rate of the stormwater runoff, or any combination of the three will not result in additional flood damage below the point of discharge of the major development. No analysis is required if the stormwater is discharged directly into any ocean, bay, inlet, or the reach of any watercourse between its confluence with an ocean, bay, or inlet and downstream of the first water control structure.
B. The stormwater runoff quantity standards shall be applied at the
site's boundary to each abutting lot, roadway, watercourse, or
receiving storm sewer system.
This section sets forth requirements to protect public safety
through the proper design and operation of stormwater management BMPs.
This section applies to any new stormwater management BMP.
A. The provisions of this section are not intended to preempt more stringent municipal or county safety requirements for new or existing stormwater management BMPs. Municipal and county stormwater management plans and ordinances may, pursuant to their authority, require existing stormwater management BMPs to be retrofitted to meet one or more of the safety standards in Subsection
B below for trash racks, overflow grates, and escape provisions at outlet structures.
B. Requirements for trash racks, overflow grates and escape provisions.
(1) A "trash rack" is a device designed to catch trash and debris and
prevent the clogging of outlet structures. Trash racks shall be installed
at the intake to the outlet from the stormwater management BMP to
ensure proper functioning of the BMP outlets in accordance with the
following:
(a)
The trash rack shall have parallel bars, with no greater than
six-inch spacing between the bars;
(b)
The trash rack shall be designed so as not to adversely affect
the hydraulic performance of the outlet pipe or structure;
(c)
The average velocity of flow through a clean trash rack is not
to exceed 2.5 feet per second under the full range of stage and discharge.
Velocity is to be computed on the basis of the net area of opening
through the rack; and
(d)
The trash rack shall be constructed of rigid, durable, and corrosion-resistant
material and designed to withstand a perpendicular live loading of
300 pounds per square foot.
(2) An overflow grate is designed to prevent obstruction of the overflow
structure. If an outlet structure has an overflow grate, such grate
shall meet the following requirements:
(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; 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.
(3) Stormwater management BMPs shall include escape provisions as follows:
(a)
If a stormwater management BMP has an outlet structure, escape provisions shall be incorporated in or on the structure. Escape provisions include the installation of permanent ladders, steps, rungs, or other features that provide easily accessible means of egress from stormwater management BMPs. With the prior approval of the municipality pursuant to §
150-12B, a freestanding outlet structure may be exempted from this requirement;
(b)
Safety ledges shall be constructed on the slopes of all new stormwater management BMPs having a permanent pool of water deeper than 2 1/2 feet. Safety ledges shall be comprised of two steps. Each step shall be four 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 to 1 1/2 feet above the permanent water surface. See Subsection
D below for an illustration of safety ledges in a stormwater management BMP; and
(c)
In new stormwater management BMPs, the maximum interior slope
for an earthen dam, embankment, or berm shall not be steeper than
three horizontal to one vertical.
C. Variance or exemption from safety standard. A variance or exemption
from the safety standards for stormwater management BMPs may be granted
only upon a written finding by the municipality that the variance
or exemption will not constitute a threat to public safety.
D. Safety ledge illustration.
Elevation View - Basin Safety Ledge Configuration
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Any person(s) who erects, constructs, alters, repairs, converts,
maintains, or uses any building, structure or land in violation of
this chapter shall be subject to a fine of not more than $2,000.