[1]
Editor's Note: The provisions of this article are mandatory
pursuant to N.J.A.C. 5:21-1.1 et seq., effective June 3, 1997. All
options of the said rules which allow preservation of rural character
at local discretion have been elected herein.
A.
These regulations shall govern any site improvements carried out
or intended to be carried out or required to be carried out in connection
with any application for residential subdivision, site plan approval,
or variance before the Planning Board or Zoning Board of Adjustment.
[Amended 12-13-1999 by Ord. No. 99-27]
B.
Except as is otherwise specifically provided, these regulations shall
control all matters concerning the construction, alteration, addition,
repair, removal, demolition, maintenance, and use of any site improvements
constructed by a developer in connection with residential development.
C.
These rules shall apply to all site improvement work and appurtenant
construction, including streets, roads, parking facilities, sidewalks,
drainage structures, grading, and utilities which are undertaken by
a developer in connection with residential development or use.
(1)
Where both residential and commercial development are planned in
a mixed-use development, these regulations shall apply to the residential
part or parts of such development where such residential part or parts
are discrete and separate from planned commercial parts as evidenced
by, for example, separate building(s), separate parking, and separate
access features.
(2)
These regulations shall apply to all utilities created by or deriving
their authority from municipal ordinance to operate within the Township
of Vernon.
(3)
Choice among options and contained in these regulations shall be
the applicant's unless otherwise specified in these regulations.
D.
Nothing contained in these regulations shall be construed to limit
the powers of the Township to enforce separate requirements concerning:
(1)
Layout, arrangement, and location of improvements, shade trees, landscaping,
or reservation of areas for public use, pursuant to N.J.S.A. 40:55D-38;
(2)
Preservation of existing natural resources; arrangement of physical
elements for safe and efficient vehicular and pedestrian circulation,
parking, and loading; screening, landscaping, and location of structures;
or conservation of energy and use of renewable resources; pursuant
to N.J.S.A. 40:55D-41; or
(3)
Use, bulk, height, number of stories, orientation, and size of buildings
and other structures; the percentage of lot or development area that
may be occupied by structures, lot sizes and dimensions, floor area
ratios, or other measures to control development intensity; or the
provision of adequate light and air pursuant to N.J.S.A. 40:55D-65.
E.
The provisions of these regulations shall not preempt or in any way
affect the exercise of any authority by the state or other county
government with respect to site improvements conferred by any state
law or any regulation promulgated thereunder. It is the intent of
these regulations to be consistent with all other applicable laws,
rules and regulations. Where these regulations and any other state
or county laws, rules or regulations establish differing requirements,
then the requirements of these regulations shall govern, except where
any such differing requirement is more restrictive.
F.
These regulations shall not apply to driveways on private property
held in fee-simple as individual residential lots outside of the public
right-of-way, including common driveways established by easements
shared by more than one dwelling unit on private property.
G.
These regulations are intended to ensure the public health, safety,
and welfare insofar as they are affected by site improvement work,
and shall be so construed.
Development of sites underlain by carbonate bedrock shall be designed in accordance with § 330-84.
A.
The Planning Board shall ensure that the plans and plats for any
residential development subject to review under this article complies
with the requirements of these regulations before issuing a preliminary
or final approval.
B.
Whenever the Zoning Board of Adjustment grants subdivision or site
plan approval pursuant to the provisions of N.J.S.A. 40:55D-76(b),
then that Board shall ensure that any plans and plats comply with
the requirements of these regulations before issuing a preliminary
or final approval.
D.
The standards referenced in these regulations shall be considered
a part of the requirements of these regulations to the prescribed
extent of each reference. Where deficiencies occur between provisions
of these regulations and referenced standards, the provisions of these
regulations shall apply, except as may be otherwise provided.
A.
Where any site improvement is required to meet any part of these
regulations pursuant to the requirements of this chapter, then the
failure of any person to construct such site improvements in accordance
with the requirements of these regulations shall constitute a violation
of the Municipal Land Use Law (N.J.S.A. 40:55D-1 et seq.). Any person
responsible for such failure shall be subject to such penalties and
enforcement procedures as are provided by that law and by any valid
ordinance adopted pursuant thereto which may be initiated by the administrative
officer designated by this chapter (N.J.S.A. 40:55D-18).
B.
In addition to any remedy provided by Subsection A above, any failure to comply with the requirements of these regulations, where compliance is required, shall constitute a failure to meet the conditions of the construction permit and/or certificate of occupancy issued pursuant to the State Uniform Construction Code Act (N.J.S.A. 52:27D-119 et seq.). Notification from the approving authority or from the Township Engineer acting on behalf of the approving authority that any of the requirements of these regulations that are conditions of the construction permit and/or certificate of occupancy have not been met shall subject any person responsible for such failure to the remedies provided under the State Uniform Construction Code Act.
A.
Any project for which preliminary subdivision or site plan approval
has been given prior to June 3, 1996, shall continue to be subject
to the design standards under which it was approved.
B.
Any project for which application is made after June 3, 1997, shall
be governed by these regulations.
C.
These regulations shall not be construed as requiring the revision
or amendment of any application for site plan or subdivision approval
which is pending on June 3, 1997. Such pending applications may, however,
be amended, provided that any such amendments shall meet the requirements
of these regulations.
(1)
For any project for which a completed application has been submitted
on or before the operative date of these regulations, but which has
not yet received preliminary approval, the applicant shall have the
option of amending the application in its entirety to comply with
these regulations or requesting that the Board continue to review
the application under the ordinances in effect at the time of application.
If any provision of these regulations or the application thereof
to any person or circumstances is held invalid, the invalidity shall
not affect other provisions or applications of the regulations which
can be given effect, and to this end the provisions of the regulations
are severable.
A.
The Board may grant such de minimis exceptions from the requirements
of these standards as may be reasonable and within the general purpose
and intent of the standards if the literal enforcement of one or more
provisions of the standards is impracticable or will exact undue hardship
because of peculiar conditions pertaining to the development in question.
B.
An application for an exception pursuant to this section shall be
filed in writing with the Board and shall include:
C.
Exceptions shall become a part of the construction documents and
shall be retained by the Board.
D.
Within 30 days of granting a de minimis exception request, the Board
shall send a copy of the document(s) constituting the de minimis exception
resolution to the New Jersey Department of Community affairs, Division
of Codes and Standards, 101 South Broad Street, CN 802, Trenton, N.J.
08625-0802. Such notice shall be clearly marked "Site Improvement
Exception(s)."
E.
An application for an exception may also be made by an officer or
agency of the Township.
F.
Examples of de minimis exceptions include, but are not limited to,
the following:
(1)
Reducing the minimum number of parking spaces and the minimum size
of parking stalls;
(2)
Reducing the minimum geometrics of street design, such as curb radii,
horizontal and vertical curves, intersection angles, center line radii,
and others;
(3)
Reducing cartway width; and
(4)
Any changes in standards necessary to implement traffic calming devices.
G.
The Board's granting of a request for a de minimis exception shall
be based on a finding that the requested exception meets the following
criteria:
In the event that the governing body, Board, and/or a developer,
nonprofit organization, or other agency shall determine that a special
area (within, or both within and without, the Township) exhibits or
will exhibit a distinctive character or environmental feature worthy
of preservation and enhancement (such as, but not limited to, redevelopment
areas, special improvement districts, historic districts, villages,
hamlets, centers, ecosystems, scenic corridors, farmland and rural
landscapes), a special area proposal or ordinance shall be prepared
and introduced for the governing body's consideration as well as the
consideration of other governing bodies in affected municipalities.
Such proposal shall be proceeded upon pursuant to N.J.A.C. 5:21-3.5.
A.
Streets shall be classified in a hierarchy with design tailored to
function. The street hierarchy definitions contained in N.J.A.C. 5:21-4.1
et seq. are applicable only to local residential streets and are not
to be considered related to the US Department of Transportation, Federal
Highway Administration's Functional Classification of Highways.
B.
The street hierarchy system shall be defined by road function and
average daily traffic (ADT), calculated by trip generation rates from
the current edition of Trip Generation by the Institute of Transportation
Engineers, as indicated in Table 4 in N.J.A.C. Title 5, Chapter 21.
Trip generation rates from other sources may be used if the applicant
demonstrates to the appropriate approving authority that these sources
better reflect local conditions. In addition, the applicant shall
investigate the opportunities for, and availability of, transit facilities
and, if appropriate, consider their impact(s) on motor vehicle traffic
trip generation rates per dwelling unit.
C.
Each residential street shall be classified and designed to meet
the standards for one of the street types defined in Table 4.2 in
N.J.A.C. Title 5, Chapter 21.
D.
The Board and the developer shall determine the highest order street
required to be used in a given residential development, considering
all of the following:
(1)
The size of the development (number and type of units). For
example, using size to determine the highest order of street required,
a development of up to 150 single-family detached units would not
require any minor collectors or streets of a higher order;
(2)
The actual or potential development of adjacent sites (whether
there is likely to be traffic passing through from neighboring developments).
A "potential" development means a development having approvals granted,
applications pending, or undergoing preliminary review; and
(3)
The streets proposed for that area, if any, as contained in
the Township Master Plan.
A.
Cartway width for each street classification shall be determined
by parking and curbing requirements that are based on intensity of
development.
B.
Intensity of development shall be based on dwelling units per gross
acre as follows:
|
Intensity
|
Dwelling Units
Per Gross Acrea
|
|---|---|
|
Low
|
Less than or equal to 4
|
|
Medium
|
More than 4 and less than
or equal to 15
|
|
High
|
More than 15
|
|
NOTE:
|
|
a In determining the intensity of
development, the gross acreage shall not include dedicated common
open space or other such areas restricted from future development.
|
C.
Cartway widths for each street classification are as shown in N.J.A.C.
Title 5, Chapter 21.
D.
Cartway width also shall be based upon consideration of possible
limitations imposed by sight distances, climate, terrain, and maintenance
needs.
A.
Curbs or curbs and gutters shall be used for drainage purposes, safety,
and delineation and protection of pavement edge. Where, based on stormwater
management system design, there is determined to be a problem with
runoff, curbs or curbs and gutters shall be used.
B.
Curb requirements shall vary according to street hierarchy and intensity
of development, in accordance with the requirements set forth in Table
4.3 in N.J.A.C. 5:21-4.2. Generally, curbs shall be required on streets
with on-street parking.
C.
Where curbing is not required, edge definition and stabilization
shall be furnished for safety reasons, and to prevent pavement unraveling.
Curbing may be required for stormwater management, road stabilization,
delineation of parking areas, 10 feet on each side of drainage inlets,
intersections, corners, and tight radii.
D.
Curb requirements may be waived by the Board, and shoulders and/or
drainage swales used, when it can be shown that soil and/or topography
make the use of shoulders and/or drainage swales preferable; and/or
the Township or Board desires to preserve community rural character
by using shoulders and/or drainage swales instead of curbs. In cases
of medium development intensity, the curbing requirement may be waived
where front setbacks exceed 40 feet and it can be demonstrated that
sufficient on-site parking exists.
E.
Flexibility regarding curb type shall be permitted as long as the curb type accommodates the system of drainage proposed. Generally, curbs should be constructed of granite block. Curbing materials shall accommodate the purposes set forth in Subsection C above.
F.
Curbs shall be constructed according to the specifications set forth
in N.J.A.C. 5:21-4.17.
G.
Curbing shall be designed to provide a curb ramp in compliance with
the Americans with Disabilities Act or the Barrier Free Subcode of
the New Jersey Uniform Construction Code (N.J.A.C. 5:23-7) at street
intersections, as applicable.
B.
Shoulders shall be provided in accordance with the requirements in
Table 4.3 in N.J.A.C. 5:21-4.2.
C.
Shoulders shall be four feet wide, except for minor collector streets
of high intensity with off-street parking; and major collector streets
of medium and high intensity shall be six feet and eight feet wide,
respectively, on each side for all streets, and located within the
right-of-way as shown in the street illustrations in N.J.A.C. Title
5, Chapter 21.
D.
Shoulders shall be constructed of materials such as stabilized earth,
gravel, crushed stone, bituminous treatment, or other forms of pavement
which provide for vehicle load support.
A.
Sidewalks and/or graded areas shall be required, depending on road
classification and intensity of development, in accordance with the
requirements set forth in Table 4.5 in N.J.A.C. 5:21-4.2.
B.
Sidewalks shall be provided where graded areas are specified in Table 4.3 in N.J.A.C. Title 5, Chapter 21, when the conditions described in Subsection B(1) or (2) below exist:
(1)
The net density of the development or project exceeds one dwelling
unit per acre; and
(a)
The development or project is located within 2,500 feet of a
train station, public or school bus route; or
(b)
The development or project is located within 2,500 feet of an
existing recreational, business or retail use or a site where such
use is permitted by existing zoning; or
(c)
Where the proposed streets connect to or extend existing streets
which have sidewalks on both sides.
(2)
The net density of the development exceeds 0.5 dwelling unit
per acre and the development is located within two miles of a school.
D.
Sidewalks shall be placed parallel to the street, as shown in the
street profile figures, unless an exception has been permitted to
preserve topographical or natural features, or if required to provide
visual interest, or unless the applicant shows that an alternative
pedestrian system provides safe and convenient circulation (e.g.,
in planned development).
E.
Pedestrianway easements at least 10 feet wide may be required by
the Board through the center of blocks more than 600 feet long. In
providing circulation or access to schools, playgrounds, shopping,
adjoining residential areas, or other community facilities, the Board
shall consider and may require pedestrianway easements.
F.
Sidewalk width shall be four feet; wider widths may be necessary
near pedestrian generators and employment centers. Where sidewalks
abut the curb and cars overhang the sidewalk, widths shall be six
feet. In high-density residential areas when sidewalks abut the curb,
a sidewalk/graded area of at least six feet in width shall be required.
G.
Sidewalks and graded areas shall be constructed according to the
specifications set forth in N.J.A.C. 5:21-4.18.
A.
Separate bicycle paths and lanes shall be required only if such paths
and lanes have been specified as part of the Township's Master Plan
and/or Official Map, as amended.
B.
Bicycle lanes, where provided, shall be placed in the outside lane
of a roadway, adjacent to the curb or shoulder. When on-street parking
is permitted, the bicycle lane shall be between the parking lane and
the outer lane of moving vehicles. Lanes shall be delineated with
markings, preferably striping. Raised reflectors or curbs shall not
be used.
C.
The construction of bikeways shall comply with the specifications
set forth in N.J.A.C. 5:21-4.18.
A.
The right-of-way shall be measured from lot line to lot line. Right-of-way
requirements are shown in Table 4.3 in N.J.A.C. 5:21-4.2 and displayed
graphically in the street illustrations in N.J.A.C. 5:21-4.5.
B.
The Board may require the right-of-way and cartway widths of a new
street that is a continuation of an existing street to be at least
the same widths as the existing street.
C.
The right-of-way shall be of sufficient width to accommodate future
development, as indicated by the Township Master Plan.
D.
Where turning lanes are needed based on safety or capacity, additional
right-of-way width, not to exceed the width and length of the turning
lanes, may be required.
Street grade and intersection design shall be constructed according
to the specifications set forth in N.J.A.C. 5:21-4.19.
A.
All electric, telephone, television, and other communication facilities,
both main and service lines serving new developments, shall be provided
by underground wiring within easements of dedicated public rights-of-way,
installed in accordance with the prevailing standards and practices
of the utility or other companies providing such services.
B.
Lots that abut existing easements or public rights-of-way, where
overhead electric or telephone distribution supply lines and service
connections have heretofore been installed, may be supplied with electric
and telephone service from those overhead lines, but the service connections
from the utilities' overhead lines shall be installed underground.
C.
Overhead lines may be permitted as an exception by the approving
authority in areas of severe geological conditions. The placement
and alignment of the poles shall be designed to lessen the visual
impact of overhead lines.
A.
Design and placement of traffic signs included in the Manual on Uniform
Traffic Control Devices for Streets and Highways shall follow the
requirements specified in the Manual on Uniform Traffic Control Devices
for Streets and Highways, published by the US Department of Transportation
and adopted by the NJ Department of Transportation.
B.
At least two street name signs shall be placed at each four-way street
intersection and one at each T-intersection. Signs shall be placed
so as not to obstruct sight distances and under light standards, if
present, so that they are clearly visible. The design of street name
signs shall be consistent, of a style appropriate to the community,
of a uniform size and color, and erected in accordance with Township
standards.
C.
At signalized intersections, street signs shall be located on the
overhead arm supporting the traffic signal, or otherwise suitably
suspended over the intersection. Roadway clearance shall be a minimum
of 15 feet from the bottom of any sign or supporting equipment and
the top of the paved surface.
A.
An adequate number of on-street and off-street parking spaces shall
be required in all developments to accommodate residents and visitors.
For projects containing dwelling units required by the New Jersey
Uniform Construction Code Barrier Free Subcode (N.J.A.C. 5:23-7) to
be accessible, accessible parking spaces for people with disabilities
shall be provided in accordance with the requirements of the Barrier
Free Subcode and shall be considered part of the total number of required
spaces.
B.
For residential developments, parking shall be provided as set forth
in Table 4.4 in N.J.A.C. 5:21-4.14. If the applicant does not specify
the number of bedrooms per unit, note "c" for each category in Table
4.4 shall apply for the parking requirement.
C.
Alternative parking standards to those shown in Table 4.4 shall be
accepted if the applicant demonstrates that these standards better
reflect local conditions. Factors affecting minimum number of parking
spaces include household characteristics, availability of mass transit,
and available off-street parking resources.
D.
A one-car garage and driveway combination shall count as 2.0 off-street
parking spaces, provided the driveway measures a minimum of 18 feet
in length between the face of the garage door and the right-of-way.
A two-car garage and driveway combination shall count as 3.5 off-street
parking spaces, provided a minimum parking area width of 20 feet is
provided for a minimum length of 18 feet as specified for a one-car
garage and driveway combination.
E.
When housing is included in mixed-use development, a shared parking
approach to the provision of parking shall be permitted.
F.
When, in the judgment of the Board, on-street parking is available,
then only that proportion of the parking requirement which is not
available on the street shall be provided in off-street parking facilities.
A length of 23 feet per on-street parking space shall be used in calculating
the number of available on-street parking spaces.
Each off-street parking space shall measure nine feet in width
by 18 feet in length. Parking spaces for people with disabilities
shall be in accordance with the New Jersey Uniform Construction Code
(N.J.A.C. 5:23-7) or the Americans with Disabilities Act, as applicable.
A.
Off-street parking areas shall be oriented to, and within a reasonable
walking distance of, the buildings they are designed to serve.
B.
Access to parking lots shall be designed so as not to induce queues
on travel ways, and to provide adequate pedestrian circulation and
safety. There shall be adequate provision for ingress to and egress
from all parking spaces to ensure ease of mobility, ample clearance,
and safety of vehicles and pedestrians.
C.
The width of all aisles providing direct access to individual parking
stalls shall be in accordance with the requirements specified in N.J.A.C.
5:21-4.6. Only one-way traffic shall be permitted in aisles serving
single-row parking spaces placed at an angle other than 90°.
D.
Where sidewalks occur in parking areas, parked vehicles shall not
overhang or extend over the sidewalk unless an additional two feet
of sidewalk width are provided to accommodate such overhang.
A.
Construction specifications for acceptable curb types of granite
block and concrete are shown in N.J.A.C. Title 5, Chapter 21.
B.
The standard concrete curb section used shall be a maximum of 20
feet in length, with a scored joint every 10 feet. All concrete used
for curbs or combination curbs and gutters shall be prepared in accordance
with the requirements, by class of concrete, of the New Jersey Department
of Transportation, Standard Specifications for Road and Bridge Construction
effective at the time of preparation. Where bituminous concrete pavement
is used for the road surface, the curb and/or gutter shall be constructed
first.
C.
Where drainage inlets are constructed but curbs are not required,
curbing must be provided at least 10 feet on each side of the inlet,
set back one foot from the extension of the pavement edge.
A.
The following apply to sidewalks and graded areas:
(1)
Sidewalks of concrete shall be four inches thick except at points
of vehicular crossing, where they shall be at least six inches thick.
At vehicular crossings, concrete sidewalks shall be reinforced with
welded wire fabric mesh or an equivalent.
(2)
Concrete air-entrained sidewalks shall be Class C concrete,
having a twenty-eight-day verification strength of 4,000 psi. Other
materials may be permitted, depending on the design of the development.
(3)
Graded areas shall be planted with grass or treated with other
suitable ground cover, and their width and cross slope shall correspond
to that of sidewalks.
A.
The following apply to street grade:
(1)
Minimum street grade permitted for all streets shall be 0.5%.
(2)
Maximum street grade shall vary by road hierarchy with flatter
grades required for roads with higher ADTs, in accordance with the
requirements shown in Table 4.6. Where terrain makes it necessary,
the allowable maximum grade may be increased by up to 2%, but shall
not exceed a maximum grade of 16%.
B.
The following apply to intersections:
(1)
Street intersections shall be as nearly at right angles as possible
and in no case shall be less than 75°.
(2)
New intersections along one side of an existing street shall,
if possible, coincide with any existing intersections on the opposite
side of each street. Use of T-intersections in subdivisions shall
be encouraged. To avoid corner-cutting when inadequate offsets exist
between adjacent intersections, offsets shall be at least 150 feet
between right-of-way center lines.
(3)
Intersections shall be rounded at the curbline with the street
having the highest radius requirement, as shown in Table 4.6 in N.J.A.C.
Title 5, Chapter 21, determining the minimum standard for all curblines.
(4)
Intersections shall be designed with a flat grade wherever practical.
(5)
The minimum center line radius, minimum tangent length between
reverse curves, and curb radii shall be as shown in Table 4.6 in N.J.A.C.
Title 5, Chapter 21.
(6)
Sight triangles shall be in accordance with 1990 AASHTO's "A
Policy on Geometric Design of Highways and Streets" standards and
based on the speed limits established by the government agency having
jurisdiction. Sight triangle easements shall be required and shall
include the area on each street corner that is bounded by the line
which connects the sight or "connecting" points located on each of
the right-of-way lines of the intersecting street. The planting of
trees or other plantings, or the location of structures exceeding
30 inches in height that would obstruct the clear sight across the
area of the easements, shall be prohibited; and a public right-of-entry
shall be reserved for the purpose of removing any object, material
or otherwise, that obstructs the clear sight.
C.
Pavement design for residential access, neighborhood, rural, parking
loop, minor collector, and major collector shall follow the specifications
shown in Figures 4.2 and 4.3 in N.J.A.C. Title 5, Chapter 21. Subgrade
categories are shown in Table 4.7.
D.
Alternative pavement design shall be allowed, provided it conforms
with one of the following: AASHTO Method of Flexible Pavement Design,
Caltrans Method of Flexible Pavement Design, Asphalt Institute Method,
AASHTO Method of Rigid Pavement Design, Fatigue Strength Method of
Design, Multilayer Elastic Analysis, or the National Crushed Stone
Association Design, incorporated herein by reference.
A.
Vertical and horizontal curves shall be designed in accordance with
1990 AASHTO's "A Policy on Geometric Design of Highway and Streets"
standards, incorporated herein by reference.
B.
Sight easements on vertical and horizontal curves shall be required
and determined based on the sight distance requirements contained
in the 1990 AASHTO's "A Policy on Geometric Design of Highways and
Streets" standards, taking into consideration the speed limits established
by the government agency having jurisdiction. Residential access,
residential neighborhood, and rural street design should be based
on a speed limit of 25 miles per hour. Minor and major collector street
design should be based on a speed limit of 30 miles per hour.
A.
The water supply system shall be adequate to handle the necessary
flow, based on complete development of the tract.
B.
When plans for future development necessitate oversizing of the water
supply system, the Township or utility authority may enter into an
agreement with the developer to address the fair share of the costs.
C.
The demand rates for all uses shall be considered in computing the total system demand. Where fire protection is provided in accordance with Subsection E below, the system shall be capable of providing the required fire demand plus the required average daily residential demand as indicated in Table 5.1 in N.J.A.C. Title 5, Chapter 21, or the peak hour flows indicated in Table 5.2 therein, whichever is greater.
D.
Average daily residential consumption shall be computed in accordance
with the housing unit type and size data shown in Table 5.1. The peak
daily flows shall be computed by applying a peaking factor of three
times the average daily residential consumption. The Township may
require deviations in the peaking factor value, provided appropriate
documentation and justification for the deviation from the standards
is provided.
E.
The design of the on-site water distribution system shall be adequate
to provide fire protection as per ISO standard, Fire Suppression Rating
Schedule, or per AWWA M31, "Manual of Water Supply Practices —
Distribution System Requirements for Fire Protection," ISO method
on pages 3-9, incorporated herein by reference.
A.
System design and placement shall comply with the following construction
specifications, incorporated herein by reference; all applicable NJ
Department of Environmental Protection (NJDEP) rules, and the American
Water Works Association (AWWA) standards, with the strictest standards
governing.
B.
Distribution mains of the overall system shall be connected into
loops so that the supply may be brought to the consumer from more
than one direction. In balancing loops in a design, the Hardy-Cross,
or an equivalent, method shall be used (see subchapter Appendix, incorporated
herein by reference). Manning roughness coefficients listed in Table
7.1 in N.J.A.C. 5:21-7.1 may be used in these calculations. Dead-end
lines shall be permitted within the design of a looped system, provided
that there are no more than 20 dwelling units permanently, or no more
than 50 dwelling units temporarily, on a dead-end line. When dead-end
lines are used, they shall be provided with a hydrant or blow-off
at the terminus as a means of flushing.
C.
Valves, except on a permitted dead end, shall be located on distribution
mains so that no more than one hydrant would be out of service as
a result of a single water main break. They shall be located in all
small branches off larger mains; and where eight-inch or larger main
lines intersect, a valve shall be located in each branch. At street
intersections, valves shall be located near pipe intersections for
ease in finding in the event of a water main break.
D.
In addition to the above requirements, water mains shall be valved
so that not more than one-quarter of a mile would be affected by a
single water main break. Geared valves on sixteen-inch mains or larger
shall be furnished.
E.
No pipe shall be placed on private property unless the owner of the
land is to own or operate the pipe, or an easement deeded to the Township
or utility authority is obtained. All easements shall be a minimum
of 20 feet wide unless depth of pipe, soil conditions, or additional
utilities require wider.
F.
A building service connection shall be comprised of a corporation
stop at the main, a curb stop and a water meter. When the meter is
located outside a building, an additional shutoff valve shall be installed
on the discharge side of the meter. When the meter is located inside
a building, valving shall be in accordance with the Plumbing Subcode
of the Uniform Construction Code (N.J.A.C. 5:23-3.15). Curb stops
and water meters shall be located as specified by the public or private
water supplier.
(1)
Separate water service connections for each unit shall be utilized
for detached housing where maintenance is the responsibility of the
individual homeowner.
(2)
Common water service connections shall be allowed for multifamily
housing where there is an entity, such as a homeowners' association,
that is responsible for the maintenance of the common water laterals.
Where common laterals are utilized, individual water shutoffs and
meters shall be provided for each unit.
G.
Where water system extensions are constructed by developers and meter
fees are not paid by the developer, the water meter(s) shall be furnished
by the developer and shall be of a manufacture and type approved by
the Township or utility authority. The meter(s) shall be read in "gallons"
or "cubic feet" as determined by the Township or utility authority.
Where meter fees are paid by the developer, the meter(s) shall be
furnished by the Township or utility authority.
H.
Pipe size shall comply with the following requirements:
(1)
Water mains shall be a minimum diameter of eight inches except
at the end of a permanent cul-de-sac, unless another size is required
for fire flow and other criteria. A six-inch main may be used when
it serves not more than 20 dwelling units and only one fire hydrant.
(2)
Building service connection pipe shall be a minimum diameter
of 3/4 inch.
(3)
Design capacity of water mains shall be such as to maintain
a minimum pressure of 20 pounds per square inch (psi) at street level
under all flow conditions.
I.
Pipe materials used in the construction of water mains shall be cement-lined
ductile iron, prestressed concrete cylinder pipe, or PVC pipe. All
pipe and appurtenances shall comply with the applicable AWWA standards
in effect at the time of application. All standards referenced in
this subsection are incorporated herein by reference.
(1)
Ductile iron pipe, appurtenances, and fittings shall comply
with ANSI/AWWA C110/A21.10 (fittings), C111/A2., 11 (gasket joints),
C115/A21.15 (flanged joints), and C151/A21.51 (pipe). Thickness shall
be designed in accordance with ANSI/AWWA C150/A21.50 and shall be
a minimum of Class 52. It shall be cement-mortar lined in accordance
with ANSI/AWWA C104/A21.4. Joints shall be gasketed push-on joints
in conformance with ANSI/AWWA C111/A21.11. The exterior of the ductile
iron pipe shall be covered with a coal-tar, epoxy-type coating. In
aggressive soils, ductile iron pipe wrapped in polyethylene, in accordance
with ANSI/AWWA C115/A21.15, shall be used.
(2)
Prestressed concrete cylinder pipe with rubber and steal joints
shall conform to ANSI/AWWA C301.
(3)
PVC pipe, appurtenances, and fittings shall conform to ANSI/AWWA
C90 for pipe sizes four inches to 12 inches, and joints shall be elastomeric-gasket
couplings of a corresponding size. Laboratory performance requirements,
as specified in ASTM D3139, shall be met. Solvent-cement couplings
shall not be permitted.
(4)
Where transitions to flanged fittings are made, adapters approved
by the Township or water purveyor shall be used.
(5)
Gate valves shall be cast-iron body with double-disc gates,
bronze-mounted or resilient-seated wedge, nonrising stem mechanical
joint as specified by the municipality or utility authority. Valves
shall be full size, and those on sixteen-inch mains or larger shall
be geared and have suitable bypasses. Valve boxes shall be of the
adjustable type with the cover marked "water" and direction of valve
operation indicated.
(6)
Building service connection pipe shall be type K copper or polyethylene
(PE) pressure pipe that complies with ANSI/AWWA C901.
J.
Pipe bedding and backfill shall be installed in accordance with the
pipe manufacturer's recommendations.
(1)
The Township or the authority may require the developer to provide
an opinion of a professional engineer relative to the suitability
of the on-site material to be used as backfill. The Township or authority
shall rely on this opinion.
(2)
Where the on-site material is deemed suitable, the opinion shall
specify the appropriate installation methods for the material. Where
the on-site material is deemed not suitable, the opinion shall specify
modification or replacement of the material and the appropriate installation
for the specified material.
A.
Hydrants shall be spaced to provide necessary fire flow. The average
building area served per hydrant shall not exceed 120,000 square feet.
In addition, the distance between any dwelling and a hydrant shall
not exceed 400 feet when measured along the street right-of-way.
B.
Size, type and installation of hydrants shall conform to the following
specifications, incorporated herein by reference, as appropriate:
(1)
Size, type, and installation of hydrants shall be in accordance
with the requirements of the Township or the water purveyor or shall
conform to the AWWA Standard for Dry-Barrel Fire Hydrants, ANSI/AWWA
C502. Hydrants shall have at least three outlets; one outlet shall
be a pumper outlet, and other outlets shall be at least 2 1/2
inches nominal size. Street main connections shall not be less than
six inches in diameter. Hose threads on outlets shall be compatible
with existing municipal equipment and shall either conform to NFPA
1963 or shall match existing municipal requirements. A valve shall
be provided on connections between hydrants and street mains. All
pipe, fittings, and appurtenances supplying fire hydrants shall be
AWWA or ASTM approved.
(2)
All fire hydrants shall conform to NFPA Standard 291.
A.
Sanitary sewer systems, where installed, shall conform to the standards
contained in this article.
B.
When plans for future development necessitate oversizing or grade
changes, the Township or utility authority may enter into an agreement
with the developer to address the fair share of the costs of improvements
not required for the proposed development.
C.
If a public sanitary sewer system will be provided to the area within
a six-year period as indicated in the municipal sewer master plan,
official map, or other official document, the Township may require
installation of a capped system within the road right-of-way or existing
utility authority easements to service the approved lots; or, alternatively,
the Township may require a performance guaranty in lieu of the improvement.
Capped sanitary sewers shall be allowed only in areas indicated for
sewer service in the State of New Jersey Statewide Water Quality Management
(WQM) Plans and where permitted by NJDEP through sewer connection
approval.
D.
Individual subsurface disposal systems shall comply with N.J.A.C.
7:9A-3.2 and 3.16.
E.
The applicant shall submit to the Township or utility authority for
review for compliance with this article details of the planned pipes,
joints, mains, laterals and appurtenances. All materials used for
sanitary sewer systems shall be manufactured in the United States,
wherever available, as governed by P.L. 1982, c. 107, effective date
October 3, 1982.[1] The details shall comply with all standards and specifications
listed in this chapter.
[1]
Editor's Note: See N.J.S.A. 40A:11-18.
A.
The planning, design, construction, installation, modification and
operation of any treatment works or sanitary system shall be in accordance
with the applicable NJDEP rules implementing the New Jersey Water
Pollution Control Act (N.J.S.A. 58:10A-1 et seq.) and the New Jersey
Water Quality Planning Act (N.J.S.A. 58:11A-1 et seq.) and, for items
not covered by NJDEP rules, with ASCE Manual on Engineering Practice
No. 37, incorporated herein by reference.
B.
Sanitary sewer pumping stations shall be considered where gravity
system design leads to excessive sewer depths which are not economically
justifiable and shall comply with N.J.A.C. 7:14A-23.10, 23.11 and
23.12.
C.
System design and placement shall comply with the following specifications:
(1)
Except where otherwise specified by the Township or utility
authority, sanitary sewer manholes, when located within the municipal
right-of-way, shall be at or near the center line of the paved cartway,
but at a five-foot minimum from the edge of the pavement. Sanitary
sewer mains shall be a minimum of 10 feet from the right-of-way line.
(2)
Easements shall be in a form approved by the utility authority
or the Municipal Engineer and Municipal Attorney. Easements shall
be required for all sanitary sewer lines which are not within a public
right-of-way. Easements shall be a minimum of 20 feet wide for sanitary
sewers that are not more than 15 feet deep. For sewers that are more
than 15 feet deep, easements shall be a minimum of 30 feet wide. The
depth of the sewer shall be measured from the design invert of the
pipe to the surface of the proposed final grading.
(3)
As with water lines, common sanitary sewer service may be permitted
for multifamily housing where there is an entity such as a homeowners'
association that is responsible for the maintenance of the common
laterals.
(4)
All sewers shall be designed to meet the New Jersey Department
of Environmental Protection's slope standards at N.J.A.C. 7:14A-23.6(b).
(5)
Pipe materials used in the construction of sanitary sewers,
including gravity sewers, shall be reinforced concrete, ductile iron,
PVC, or clay pipe. All pipe and appurtenances shall comply with AWWA
and ASTM standards referenced in this section, which are incorporated
herein by reference.
(a)
Reinforced concrete pipe shall be used only in sizes 24 inches
and larger and shall meet all the requirements of ASTM C76. All pipe
shall be Class III strength installed with Class C ordinary bedding,
except in the following conditions where stronger pipe may be required:
[1]
For depths less than three feet, measured from the top of the
pipe, installed under traffic areas, Marston Class IV pipe shall be
required.
[2]
The presence of clay soils, poor bedding conditions, or other
unusual loading conditions shall be given special consideration, and
the developer shall submit an engineering analysis to the Township
or authority for approval.
(b)
PVC sewer pipe shall have bell and spigot ends and O-ring rubber
gasketed joints. PVC pipe and fittings shall conform to ASTM D3034,
with a minimum wall thickness designation of SDR 35.
[1]
The plastic material from which the pipe and fittings are extruded
shall be impact types of PVC, unplasticized, having high mechanical
strength and maximum chemical resistance conforming to Type 1, Grade
1 of the specification for rigid polyvinyl chloride compounds, STM
D1784.
[2]
Pipe shall be free from defects, such as bubbles or other imperfections,
in accordance with accepted commercial practice. Test results demonstrating
that the pipe meets ASTM D2444 for impact and ASTM D2321 for deflection
and pipe stiffness shall be provided when requested by the municipality
or utility authority.
[3]
Joints shall conform to ASTM D3212. Rubber ring gaskets shall
conform to ASTM F477. The gasket shall be the sole element depended
upon to make the joint watertight.
[4]
The pipe shall be installed as specified in ASTM D2321. In no
case shall less than a Class III material be used for bedding and
haunching material, unless approved in writing by the Municipal Engineer
or utility authority engineer. When installing pipe in unstable soil
or excessive groundwater, a determination regarding special precautions,
such as poured concrete slabs, shall be made by the Municipal Engineer
or utility authority engineer.
(c)
Ductile iron pipe shall be centrifugally cast in metal or sand-lined
molds to ANSI/AWWA C151/A21.51. The joint shall be of a type that
employs a single, elongated, grooved gasket to effect the joint seal.
Pipe should be furnished with flanges where connections to flange
fittings are required. Pipe shall be a minimum of Class 50. The outside
of the pipe shall be coated with a uniform thickness of hot applied
coal tar coating; the inside shall be lined with cement in accordance
with ANSI/AWWA C104/A21.4. Ductile iron pipe shall be installed with
Class C, Ordinary Bedding, when site conditions allow. In corrosive
soils or on sewers that receive discharge from a force main where
hydrogen sulfide is present, ductile iron pipe with polyethylene coating,
which protects the interior and exterior of the pipe, shall be used.
(d)
Clay pipe shall comply with ASTM C700.
(6)
Inverted siphons, force mains, and outfalls shall be constructed
of ductile iron pipe or PVC pipe, as specified above. Inverted siphons
shall consist of two pipes with provisions for flushing. Flow control
gates shall be provided in the chambers.
(7)
In addition to the pipe materials at N.J.A.C. 7:14A-23.6(b)5,
PVC pipe shall be considered a suitable material.
(8)
For other than PVC pipe, pipe and manhole bedding and backfill
shall be provided as specified in "Design and Construction of Sanitary
and Storm Sewers, ASCE Manual on Engineering Practice No. 37," prepared
by the Joint Committee on the American Society of Civil Engineers
and the Water Pollution Control Federation, New York, 1969. Any pipe
material not covered by this manual shall be installed in accordance
with the manufacturer's recommendations.
(a)
The Township or the authority may require the developer to provide
an opinion of a professional engineer regarding the suitability of
the on-site material to be used as backfill. The Township or authority
shall rely on this opinion.
(b)
Where the on-site material is deemed suitable, the opinion shall
specify the appropriate installation methods for the material. Where
the on-site material is deemed not suitable, the opinion shall specify
modification or replacement of the material and the appropriate installation
methods for the specified material.
(9)
Manholes shall comply with the standards in ASCE Manual on Engineering
Practice No. 37, and shall meet the following requirements:
(a)
Manholes shall be precast concrete or concrete block. Concrete
block shall be coated with two coats of Portland cement mortar. Precast
concrete or concrete block shall be sealed with two coats of an acceptable
waterproofing tar, asphalt, or polyplastic alloy, with enough time
allowed to bond between the sealed coats.
(b)
Masonry brick, concrete block, or half rings may be used to
make vertical adjustments to rims.
(c)
Where pipe size varies, crowns of pipes shall be matched, except
in special conditions, as required by applicable NJDEP rules.
(d)
If precast manhole barrels and cones are used, they shall conform
to ASTM C478, with round rubber gasketed joints conforming to ASTM
C361 and ASTM C443. Maximum absorption shall be 9%, in accordance
with ASTM C478, Method A. The entire outside surface of the manhole
shall be coated with a bituminous waterproofing material acceptable
to the Municipal Engineer or utility authority. Cracked manholes shall
not be used. The top riser section of precast manholes shall terminate
less than one foot below the finished grade to provide for proper
adjustment.
(e)
Manhole frames and covers shall be of cast iron and shall conform
to ASTM A48, Class 30, and shall be suitable for H-20 loading capacity.
All manhole covers in unpaved rights-of-way or in remote areas shall
be provided with a locking device, as specified by the municipality
or utility authority. The word "SEWER" shall be cast integrally into
the manhole cover.
(f)
Where watertight and low profile frames and covers are utilized,
they shall conform to ASTM C923. Manholes shall be supplied with flexible,
watertight adaptors, such as inserts or gaskets, suitable for the
pipe materials used.
(10)
Laterals and cleanouts shall comply with the following:
(a)
The house connection or lateral from the street main to the
cleanout shall be considered an integral part of the sanitary sewer
system. The type of material used for the house connection shall be
as follows: four-inch cast iron soil pipe, extra heavy; four-inch
PVC pipe, Schedule 40; four-inch ABS plastic pipe, SDR 35; or four-inch
ductile iron pipe. Common laterals for multifamily units shall be
designed to have adequate conveyance capacity.
(b)
Wye connections shall be the same material as the sewer main.
Saddles shall be used only for connection to an existing main.
(c)
Bends in house connection lines shall be made using standard
fittings. A riser with a cleanout shall be provided in the lateral
between the edge of the pavement and property line or within a designated
easement as determined by the municipality.
(d)
Inspection cleanouts or observation tees within the easement
or right-of-way shall be fitted with either a metallic cap or a nonmetal
cap fitted with a metallic plug that is suitable for locating the
cleanout. Caps shall have a depressed or inverted nut. The inspection
cleanout or observation tee shall be placed between the curb or edge
of pavement and property line or within a designated easement.
(e)
Connections beyond the cleanout are under the jurisdiction of
the Plumbing Subcode of the Uniform Construction Code (N.J.A.C. 5:23-3.15)
through the Plumbing Subcode Official. The pipe size and specifications
shall comply with the regulations and requirements of the Plumbing
Subcode of the Uniform Construction Code.
(f)
As-built drawings that include the location of plumbing wyes,
as supplied by the contractor, shall be submitted to the Township
Engineer.
A.
Stormwater management systems prepared by design engineers shall
emphasize a natural, as opposed to an engineered, drainage strategy.
B.
The applicability of a natural approach depends on such factors as
site storage capacity, open channel hydraulic capacity, and maintenance
needs and resources. N.J.A.C. 7.6(c)4 references authoritative sources
on natural and nonstructural approaches. Applicability of a stormwater
approach also can be limited by regulatory constraints that govern
certain structures (e.g., dams) or areas (e.g., development in a floodplain
or wetland). See N.J.A.C. 5:231-7.5(c).
C.
Construction practices shall conform to Standards for Soil Erosion
and Sediment Control in New Jersey, N.J.A.C. 2:90-1, as administered
by the New Jersey Department of Agriculture.
D.
Design engineers shall determine hydraulic capacity for open-channel
or closed-conduit flow based on the Manning equation, or charts/nomographs
based on this equation. The hydraulic capacity is term "Q" and is
expressed as discharge in cubic feet per second as follows:
|
Q = (1.486/n) A R 2/3 S 1/2
| ||
|
Where
| ||
|
n
|
=
|
Manning's roughness coefficient
|
|
A
|
=
|
Cross-section area of flow in square feet
|
|
R
|
=
|
Hydraulic radius in feet, R = A/P, where P is equal to the wetted
perimeter, measured in feet and defined as the length of the line
of contact between the flowing water and the channel
|
|
S
|
=
|
Slope of energy grade line in feet per foot
|
E.
The Manning roughness coefficients used by design engineers appear
in Table 7.1 in N.J.A.C. 5:21-7.2.
(1)
A direct application of Manning's equation may be used for piped
stormwater systems. As an option, design engineers can use a standard
step backwater calculation for storm sewer systems if the use of this
approach is deemed appropriate by the designer. For other than pipe
storm sewer systems, design engineers shall apply Manning's equation
only when the bottom slope of the channel, energy grade line, and
water surface (hydraulic grade line) are parallel, where the flow
regime is in the turbulent range of Reynolds number and where the
boundaries of the cross section of the channel do not move.
F.
Velocities in open channels, excluding water quality swales, at design
flow shall not be less than 0.05 of a foot per second and no greater
than a velocity that will begin to cause erosion or scouring of the
channel. Design engineers shall determine permissible velocities for
swales, open channels, and ditches using methods presented in Standards
for Soil Erosion and Sediment Control in New Jersey, N.J.A.C. 2:90,
New Jersey State Soil Conservation Committee, Division of Rural Resources,
New Jersey Department of Agriculture, revised to date.
G.
Velocities in closed conduits at design flow shall be at least two
feet per second but not more than the velocity that will cause erosion
damages to the conduit, as per the manufacturer's specifications.
Minimum allowable pipe slopes shall produce velocity of at least two
feet per second when the flow depth is full or half of the pipe diameter.
H.
Design engineers shall base culvert capacity on inlet/out analysis,
as specified in Hydraulic Design of Highway Culverts, Hydraulic Design
Series (HDS) No. 5, Report No. FHWA-IP-85-15, US Department of Transportation,
Federal Highway Administration, September 1985, incorporated herein
by reference.
A.
Watershed stormwater management requires the determination of a watershed
runoff hydrograph that displays and compares the peak discharge rate
and volume. Both parameters shall compare pre- and post-development
conditions. The design engineer shall determine the status of the
drainage area. All significant land features such as ponds, depressions,
or hedgerows that increase ponding factors shall be considered by
the design engineer to compute pre-development runoff. If the design
engineer is able to verify that a given hydrologic condition has existed
on the site for a period of at least five years prior to the time
of computation, then this existing condition may be used by the design
engineer to determine runoff coefficients. As an alternative, however,
the design engineer should assume the drainage area in the pre-development
condition to be in good hydrologic condition (if the lands are pastures,
lawns, or parks), to have good cover (if the lands are woods), or
to have had conservation treatment (if the lands are cultivated).
B.
Design engineers shall use the runoff hydrograph peak rate to determine
the configuration and sizes of pipes, channels, and other routing
or flow-control structures. They shall use runoff volume calculations
generated by the hydrograph to determine the necessity for, and sizing
of, detention and retention facilities.
C.
For the runoff peak rate of discharge calculation, design engineers
shall have the option to choose the methodology to estimate peak rate
of discharge. For relatively small drainage areas of up to 1/2 square
mile (320 acres), the peak rate of runoff may be calculated by the
Rational Method, its derivatives, or the referenced methods that follow:
(1)
For areas greater than 320 acres, design engineers shall calculate
peak rate of runoff in accordance with the following procedures and
methods, incorporated herein by reference:
(a)
Urban Hydrology for Small Watersheds, Technical Release No.
55 (Tr-55) US Department of Agriculture, Soil Conservation Service,
Engineering Division, as supplemented or amended to date;
(b)
Computer Program for Project Formulation — Hydrology,
Technical Release No. 20 (TR-20), US Department of Agriculture, Soil
Conservation Service, Engineering Division, as supplemented or amended
to date; or
(c)
The New HEC-1 Flood Hydrograph Package, Technical Paper No.
82, Hydraulic Engineering Center, US Army Corps of Engineers, used
in appropriate conditions with appropriate values.
(2)
The equation for the Rational Method is:
|
Qp = C I A
| ||
|
Where
| ||
|
Qp
|
=
|
The peak runoff area in cubic feet per second
|
|
C
|
=
|
The runoff coefficient
|
|
I
|
=
|
The average rainfall intensity in inches per hour occurring
at the time of concentration tc
|
|
A
|
=
|
The size of the drainage area in acres
|
(a)
Typical C values for one-hundred-year frequency storm events
appear in Table 7.2 in N.J.A.C. Title 5, Chapter 21. Coefficients
for recurrence intervals more frequent than the one-hundred-year storm
should be reduced in accordance with Table 7.3 in N.J.A.C. Title 5,
Chapter 21.
(b)
The Rational Method is most accurate when dealing with uniform
drainage areas. Design engineers may divide nonuniform drainage areas
into uniform subdrainage areas and calculate the runoff from each
of these areas separately, or they may use the weighted average technique
for a composite drainage area. Design engineers also may use runoff
coefficients from the following sources, incorporated herein by reference:
[1]
Design of Roadside Drainage Channels — Hydraulic Design
Series No. 4, Report No. FHWA-EPD-86-103, May 1965, US Department
of Transportation, Federal Highway Administration, as supplemented
or amended to date; and
[2]
Airport Drainage, AC 150/532-5B, US Department of Transportation,
Federal Aviation Administration, July 1970, as supplemented or amended
to date.
(3)
Design engineers may estimate time of concentration (tc) with Figure 7.1 in N.J.A.C. Title 5, Chapter 21, Time
of Concentration nomograph from Design Manual — Roadway, New
Jersey Department of Transportation, Division of Roadway Design, Bureau
of Roadway Design Standards, May 1992. Use of this figure is limited
to the design of storm sewer systems. For other purposes, design engineers
shall use the procedures outlined in Chapter 3 of Technical Release
No. 55, Urban Hydrology for Small Watersheds (TR-55) US Department
of Agriculture, Soil Conservation Service, Engineering Division, as
supplemented or amended to date.
(4)
When using the Rational Method, rainfall intensity as a function
of duration and storm frequency shall be based upon Figure 7.2 in
N.J.A.C. Title 5, Chapter 21, Rainfall Intensity Curves and/or local
rainfall frequency data, where available. A copy of Figure 7.2 in
N.J.A.C. Title 5, Chapter 21, appears in the New Jersey Department
of Transportation's Design Manual — Roadway, May 1992. In all
instances, design engineers shall use a minimum time of concentration
of 10 minutes. For storm sewer design, a ten-year to twenty-five-year
storm frequency consistent with localized circumstances should be
considered as a minimum, unless special circumstances are involved
such as inadequate downstream stormwater facilities, lack of positive
overland relief, or evidence of local flooding. In such special circumstances,
design engineers shall design facilities to accommodate, as a minimum,
the following storm frequencies:
(a)
Ten-year storm for storm drain systems where excess flow can
continue downgrade in the street and not exceed the gutter capacity.
Also, ten-year storms shall be used at low points in storm drain systems
with overland relief.
(b)
Twenty-five-year storm where flow in a storm drain is totally carried by pipe when conditions under Subsection C(4)(a) above do not apply.
(c)
Twenty-five-year storm for culvert design where the culvert
will be located in streams shown as a blue line on the New Jersey
State Atlas or the United States Coast and Geodetic survey maps. Culverts
with an upstream drainage area of 50 acres or more shall be designed
to accommodate a one-hundred-year frequency storm in accordance with
Flood Hazard Area Control Regulations, N.J.A.C. 7:13-2.16.
(d)
Twenty-five-year storms for open channels where the upstream
drainage area is less than 50 acres. When the upstream drainage area
is 50 acres or more, design engineers shall design open channels to
accommodate the one-hundred-year storm, in accordance with Flood Hazard
Area Control Regulations, N.J.A.C. 7:13-2.16.
(5)
The size of the drainage area shall include on-site and off-site
lands contributing to the design point.
(6)
Computer software adaptations of the Rational Method or the
S.C.S. TR-55 are acceptable, provided their data and graphic printout
allow review and evaluation.
D.
Design engineers shall use a consistent method to calculate peak
rate of runoff and volume. If either TR-55, TR-20, or HEC-1 is used
to calculate peak rate of runoff, then the same method shall be used
to determine volume. If the Rational Method is used for peak flow
calculations, design engineers shall use the Modified Rational Method
to calculate peak volume to be used for basin routing. A maximum drainage
area of 20 acres all be used for the Modified Rational Method.
A.
Design engineers shall determine pipe size based on design runoff,
conduit entrance conditions, and hydraulic capacity.
B.
In general, no pipe size in the storm drainage system shall be less
than 15 inches in diameter. Design engineers may use a twelve-inch
diameter pipe as a cross-drain to a single inlet. Design engineers
shall use the Manning equation to determine hydraulic capacity of
pipes.
C.
All discharge pipes shall terminate with an appropriate precast concrete
or flared-end section or concrete headwall with or without wingwalls,
as conditions require. Design engineers shall consider such site conditions
as slope, soil stability, vegetation, grade, and size of conduit to
determine whether or not to use wingwalls.
D.
Materials used in the construction of storm sewers shall be constructed
of reinforced concrete, ductile iron, or corrugated polyethylene,
or, when approved by the Township Engineer, corrugated metal. The
most cost-effective materials shall be permitted that conform to local
site conditions and reflect the relevant operations, maintenance,
and system character of the municipal stormwater system. Specifications
referred to, such as ASTM or AWWA, etc., should be the latest revision
in effect at the time of application.
(1)
The following apply to reinforced concrete pipe:
(a)
Circular reinforced concrete pipe and fittings shall meet the
requirements of ASTM C76.
(b)
Elliptical reinforced concrete pipe shall meet the requirements
of ASTM C507.
(c)
Joint design and joint material for circular pipe shall conform
to ASTM C443.
(d)
Joints for elliptical pipe shall be bell and spigot or tongue
and groove sealed with butyl, rubber tape, rubber ring gaskets, or
external sealing bands conforming to ASTM C877.
(e)
All pipe shall be Class III, minimum unless loading conditions
call for stronger pipe (i.e., higher class).
(f)
The minimum depth of cover over the concrete pipe shall be as
designated by the American Concrete Pipe Association that follows:
(g)
Minimum depth of cover standards for ductile iron and corrugated
polyethylene pipe shall conform to manufacturer standards.
(2)
Ductile iron pipe shall be centrifugally cast in metal or sand-lined
molds to ANSI/AWWA C151/A21.51. The joints shall conform to ANSI/AWWA
C111/A21.11. Pipe shall be furnished with flanges where connections
to flange fittings are required. Pipe should be Class 50 (minimum).
The outside of the pipe should be coated with a uniform thickness
of hot applied coal-tar coating and the inside lined with cement,
in accordance with ANSI/AWWA C104/A21.4. Ductile iron pipe shall be
installed with Class C Ordinary Bedding, unless soil conditions dictate
otherwise.
(3)
Corrugated polyethylene pipe shall be high density, smooth interior
pipe and shall conform to AASHTO M294, "Specifications for Corrugated
Pipe," twelve- to thirty-six-inch diameter. Materials shall conform
to ASTM D3350, "Standard Specification for Polyethylene Plastics Pipe
and Fittings Materials." Pipe joints and fittings shall be compatible
with the pipe material and shall conform to the same standards and
specifications as the pipe material. Pipe couplers shall not cover
less than one full corrugation on each section of pipe. Installation
shall be in accordance with ASTM D2321, "Practice for Underground
Installation of Themoplastic Pipe for Sewers and Other Gravity-Flow
Applications." Backfill material shall be placed in six-inch lifts
and compacted to 95% minimum dry density, per AASHTO T99. In areas
of high groundwater tables, design engineers shall check for flotation.
(4)
Corrugated metal pipe, when approved by the Municipal Engineer,
shall meet the requirements and be installed in the manner specified
in N.J.A.C. Title 5, Chapter 21.
E.
Pipe bedding and backfill shall be provided as specified in Design
and Construction of Urban Stormwater Management Systems, ASCE Manuals
and Reports of Engineering Practice No. 77, 1993, incorporated herein
by reference. Bedding and backfill for any pipe material not covered
by this manual shall be installed in accordance with manufacturer's
recommendations. The Township Engineer may require the developer to
provide professional certification as to the suitability of backfill
material and where such suitability does not exist, any modifications
needed to use on-site material and the appropriate methods to install
this material. The Township and/or utility engineer shall rely on
this certification.
F.
Maintenance easements shall be provided around stormwater facilities
located outside of the public right-of-way. The size of the easement
shall be dictated by working needs.
A.
Design engineers shall design inlets, catch basins, and manholes
in accordance with the New Jersey Department of Transportation's Standard
Specifications for Road and Bridge Construction (1989). Design engineers
shall use bicycle-safe grates. For Type A inlets, they should use
a frame and single grate. Type B inlets require a frame, grate, and
curb-type inlet with back piece. Type E inlets require a frame and
double grate.
B.
Inlet spacing depends on the inlet capacity. Maximum distance between
inlets is 400 feet. The maximum capacity of a curb inlet shall be
six cubic feet per second. Area inlets in parking lots should be limited
to three cubic feet per second.
C.
Manholes shall be precast concrete or concrete block coated with
two coats of portland cement mortar outside the manhole. Masonry brick
may be used to make vertical adjustment to rims, as long as the adjustments
are 12 inches or less. In acidic soils, all manholes shall have two
coats of black bitumastic waterproofing applied per manufacturer's
instruction.
D.
If precast manhole barrels and cones are used, they shall conform
to ASTM Specification C478, with round rubber gasketed joints, conforming
to ASTM Specification C923. Both ASTM specifications are incorporated
herein by reference. Maximum absorption shall be 8% in accordance
with ASTM Specification C 478, Method A.
E.
If precast manholes are used, the top riser section shall terminate
less than one foot below the finished grade, and the manhole cover
shall be flush with the finished grade.
F.
Manhole frames and covers shall be of cast iron, conforming to ASTM
Specification A48, Class 30 incorporated herein by reference, and
be suitable for H-20 loading capacity. Manhole covers in remote locations
may have a locking device.
G.
Outlet grates, fences and other safety features for stormwater management
facilities shall conform with New Jersey Department of Environmental
Protection's Stormwater Management Rules, N.J.A.C. 7:8. Safety requirements
for detention basin and other stormwater facilities are incorporated
in N.J.A.C. 5:21-7.5(f)7.
H.
The channel should be, insofar as possible, a smooth continuation
of the pipe. The pipe may be laid through the manhole and top half
removed by saw cut. The completed channel should be U-shaped. The
channel height shall be 3/4 of the diameter of the pipe. The bench
should provide good footing for a workman and a place where minor
tools and equipment can be laid. It must have a slope of 4% to 8%.
A.
Development shall use the best available technology to accommodate
stormwater management by natural drainage strategies where possible
and practicable. Detention facilities, when required or selected,
shall be designed, constructed, and maintained according to the following
standards.
B.
Design engineers shall coordinate structural detention requirements
with nonstructural practices, such as cluster land use development,
open space acquisition, stream encroachment and flood hazard controls.
C.
Detention and all other stormwater facilities shall conform to the
New Jersey Department of Environmental Protection's Stormwater Management
Rules, at N.J.A.C. 7:8-3.4. Design engineers shall also adhere to,
when applicable, the stormwater design requirements in the following
rules:
D.
Where detention facilities are deemed necessary, they shall accommodate
site runoff generated from two-year, ten-year, and one-hundred-year
storms as routed to the basin, considered individually, unless the
detention basin is classified as a dam, in which case the facility
also must comply with the Dam Safety Standards, N.J.A.C. 7:20.
(1)
These design storms shall be defined as either a twenty-four-hour
storm using Type III rainfall distribution when using US Soil Conservation
Service procedures (such as TR-20 or TR-55 tabular method), or the
design storm resulting in the greatest storage volume to achieve the
required outflow using a design method such as the Modified Rational
Method. Runoff greater than that occurring from the one-hundred-year,
twenty-four-hour storm will be passed over an emergency spillway.
(a)
A map of approximate geographic boundaries for SCS rainfall
distributions presented on page B-2 of the June 1986 Edition of TR-55
shows all of New Jersey in the Type III region. Although the May 1982
version of TR-20 does not include a standard SCS twenty-four-hour,
cumulative Type III distribution rainfall table like it does for Type
I, IA and II, there is a version (Version 2.04 TEST) of the program
available from the SCS which does. The Type III distribution also
can be manually added to a TR-20 model by using a RAINFL table.
(2)
Detention facilities shall be designed to accommodate runoff
from the development of the site for the one-, ten- and one-hundred-year
storm events so that predevelopment peak flow rates that impact on
down stream properties, watercourses, and/or drainage systems are
not increased.
(3)
If there is not a regional stormwater plan, then the design
engineer shall design detention facilities such that the post-project
construction peak runoff for the two-year storm event is 50% of the
pre-project construction peak runoff rate. The post-project construction
peak runoff rates for the ten- and one-hundred-year storm events shall
be 75% and 80%, respectively, of the pre-project construction peak
runoff rates. It should be noted that these percentages only apply
to the portion of the post-project runoff from the site under development.
Off-site runoff may be computed at 100% of the pre-project rate.
(4)
If a Phase II stormwater management plan for the region or watershed
exists, consistent with stormwater rules administered by the New Jersey
Department of Environmental Protection, N.J.A.C. 7:8, then the design
engineer may design stormwater management systems to conform to that
plan. For some parts of the watershed, this may mean a detention basin
is unnecessary.
(5)
If the development site is not part of a Phase II regional or
watershed stormwater management plan, then the design engineer may
model the watershed, consistent with regulations administered by the
Department of Environmental Protection, and design stormwater management
facilities to conform to that plan. This analysis shall include impacts
of existing development and all potential future development in the
drainage area. For some parts of the watershed, this may mean detention
is unnecessary.
E.
Design engineers shall locate detention facilities (either "wet"
or "dry") so as not to interfere or adversely affect existing surface
waters on the site or adjacent to the site. Excavation for detention
facilities shall be designed to be the maximum practical distance
above seasonally high groundwater elevation. In the case of wet detention
facilities, storage may only be presumed to be available above the
elevation of the seasonal high groundwater. If the facility is designed
as an infiltration basin, the bottom of the basin shall be a minimum
of two feet above the elevation of the seasonally high water table.
F.
The following list of general structural criteria shall be used to
design stormwater detention basins:
(1)
Detention components: principal basin control structure (quantity
control), as follows:
(a)
Principal basin control structures will consist of orifice and/or
weir control devices. Design engineers shall design orifices based
upon the following equation:
|
Q = C A (2gH)0.5
| ||
|
Where
| ||
|
Q
|
=
|
The flow rate in cubic feet per second
|
|
C
|
=
|
0.6 (The orifice flow coefficient "C" may vary, depending on
entrance conditions. Design engineers may also use other coefficients
with appropriate references.)
|
|
A
|
=
|
Cross section area of flow in square feet
|
|
H
|
=
|
The vertical distance in feet between the center of the orifice
and the water surface
|
|
2g
|
=
|
64.4 feet per second
|
|
To minimize the chance of clogging, orifices intended solely
for runoff quantity control will be at least six inches in diameter
(or its equivalent). All joints are to be watertight. In addition,
trash racks and/or anti-vortex devices shall be required. When weirs
are used alone or in conjunction with orifices, design engineers shall
use the following equation:
| ||
|
Q = CwL(h)3/2
| ||
|
Where
| ||
|
Q
|
=
|
The flow rate in cubic feet per second
|
|
Cw
|
=
|
3.2 (design engineers may use other coefficients with appropriate
references)
|
|
L
|
=
|
Length of the weir in feet
|
|
H
|
=
|
The vertical distance in feet between water surface and elevation
and the crest of the weir
|
|
All weirs shall be constructed as part of a reinforced concrete
structure with appropriate grates.
| ||
(b)
Eight-inch thick, antiseep collars are to be installed along
outlet pipes. Reinforcement steel shall be No. 5 bars at 12 inches
both ways, with two inches of cover on both faces (minimum).
(c)
Where necessary for stability of the outlet pipe, a concrete
cradle shall be provided.
(d)
All principal basin control structures shall be precast or reinforced
concrete. All joints are to be watertight.
(e)
Suitable lining shall be placed upstream and downstream of principal
basin control structures, as necessary, to prevent scour and erosion.
Such lining shall conform to Standards for Soil Erosion and Sediment
Control in New Jersey, N.J.A.C. 2:90, promulgated by the NJ State
Soil Conservation Committee.
(2)
Detention components; emergency spillways, as follows:
(a)
Vegetated emergency spillways shall have side slopes not exceeding
three horizontal to one vertical.
(b)
Maximum velocities in emergency spillways shall be checked based
on the velocity of the peak flow in the spillway resulting from the
routed emergency spillway hydrograph. The design of the emergency
spillway will be based on the one-hundred-year inflow to the basin,
except for Class IV dams, which shall comply with the Dam Safety Standards,
N.J.A.C. 7:20. The design of the emergency spillway assumes the principal
spillway is malfunctioning and will not allow any discharge or flow.
Where maximum velocities exceed those contained in Table 7.5 in N.J.A.C.
5:21-7.5, suitable lining shall be provided.
(c)
Where maximum velocities exceed the allowable velocities for
soil stability as determined in the Standards for Soil Erosion and
Sediment Control in New Jersey, N.J.A.C. 2:90, promulgated by the
NJ State Soil Conservation Committee, suitable lining should be provided.
Design engineers also may check maximum velocities in emergency spillways
based on the velocity of the peak flow in the spillway resulting from
the routed emergency spillway hydrograph. Where maximum velocities
exceed those contained in Table 7.5 in N.J.A.C. 5:21-7.5, suitable
lining shall be provided. Linings shall meet specifications required
in Hydraulic Engineering Circular No. 15 - Design of Stable Channels
with Flexible Linings, published by the US Department of Transportation,
Federal Highway Administration or Standards for Soil Erosion and Sediment
Control in New Jersey, N.J.A.C. 2:90, promulgated by the State Soil
Conservation Committee, New Jersey Department of Agriculture.
(3)
Detention components; dams, as follows:
(a)
"Dam" refers to any artificial dike, levee, or other barrier
with appurtenant work that is constructed to impound water on a permanent
or temporary basis and raises the water level five feet or more above
the usual, mean, low-water height when measured from the downstream
toe-of-dam to the emergency spillway crest, or, in the absence of
an emergency spillway, the top of the dam.
(b)
Design engineers shall design all dams in accordance with Dam
Safety Standards, N.J.A.C. 7:20, administered by the New Jersey Department
of Environmental Protection.
(4)
Detention basin berms and embankment ponds, as follows:
(a)
A detention basin berm is a water impoundment made by either
constructing an embankment (a facility referred to as an "embankment
pond") or excavating a pit or dugout that does not qualify as a dam.
Detention basin berms constructed by the second method are referred
to as "excavated ponds."
(b)
Site conditions shall be such that runoff from the design storm
can safely pass through; a natural or constructed emergency spillway
designed to accept the entire one-hundred-year flow; a combination
of a principal spillway and the emergency spillway designed to ensure
passage of the one-hundred-year flow when either the principal spillway
and/or the emergency spillway flows are impeded by debris; or a principal
spillway designed so as to allow it to continue to function reliably,
passing the one-hundred-year flow, when impeded by debris.
[1]
Drainage area of the pond shall be protected against erosion
so that expected sediment does not shorten the planned effectiveness
of the structure.
[2]
When necessary, embankment ponds shall have foundation cutoff
walls of relatively impervious material under the berm. The cutoff
walls shall extend up to abutments as required and be deep enough
to extend into a relatively impervious layer, or provide for a stable
structure when combined with seepage control. The cutoff trench shall
have a bottom width adequate to accommodate the equipment used for
excavation, backfill and compaction operations. Cutoff wall side slopes
shall not be steeper than one horizontal to one vertical. The cutoff
walls shall extend up to the normal water line, and the minimum depth
shall be at least three feet.
[3]
Design engineers shall include seepage controls if previous
layers are not intercepted by the cutoff, seepage creates swamping
downstream, such control is needed to insure a stable embankment,
or special problems may require drainage for a stable berm. Seepage
may be controlled by foundation, abutment, or embankment drains; reservoir
blanketing; or a combination of these measures.
[4]
The minimum top width for a berm shall be six feet. The minimum
top width of dams should be 10 feet.
[5]
All slopes must be designed to be stable. If needed to protect
the slopes of the berm, special measures such as rock riprap, sand
gravel, fabrics, geofabrics, geomembranes, or special vegetation shall
be provided as specified by the standards in Guide for Design and
Layout of Vegetative Wave Protection for Earth Dam Embankments, Technical
Release No. 56 and Riprap for Slope Protection Against Wave Action,
Technical Release No. 69. Both reports are published by the US Department
of Agriculture, Soil Conservation Service, and are incorporated herein
by reference.
[6]
The minimum elevation of the top of the settled embankment shall
be one foot above the water surface in the detention basin, with the
emergency spillway flowing at the design depth. The minimum difference
in elevation between the crest of the emergency spillway and the settled
top width of the structure shall be two feet for all berms having
more than a twenty-acre drainage area or more than 20 feet in effective
height. Design engineers shall increase the design height of the structure
by the amount needed to insure that after settlement the height of
the berms equals or exceeds the design height. This increase shall
not be less than 5%, except where detailed soil testing and laboratory
analysis shows that a lesser amount is adequate.
[7]
Design engineers shall place a pipe conduit with needed appurtenances
under or through the berm except where rock, concrete, or other types
of mechanical spillways are used or where the rate and duration of
flow can be safely handled by vegetated or earth spillway.
(c)
The design elevation of the top of all embankments and berms
shall be one foot or greater than the maximum water surface elevation
in the basin, when stormwater from the one-hundred-year flood passes
over the emergency spillway. The "design height," defined as the vertical
distance from the top to the bottom of the deepest cut, shall be constructed
to insure that the top elevation will be maintained following all
settlement.
[1]
When the design discharge of the principal spillway is considered
in calculating peak outflow through the emergency spillway, the crest
elevation of the inlet shall be such that the full flow will be generated
in the conduit before there is discharge through the emergency spillway.
The inlets and outlets of the principal spillway shall be designed
to function satisfactorily for the full range of flow and hydraulic
head anticipated. The capacity of the pipe conduit shall be adequate
to discharge long-duration, continuous or frequent flows without flow
through the emergency spillways. The pipe diameter shall be no less
than six inches. If the pipe conduit diameter is larger than 10 inches,
its design discharge may be considered when calculating the peak outflow
rate through the emergency spillway.
[2]
Pipe conduits under or through the berm shall be capable of
withstanding external loading without yielding, buckling, or cracking.
Flexible pipe strength shall not be less than that necessary to support
the design load with the maximum of 5% deflection. The inlets and
outlets shall be structurally sound and made of materials compatible
with those of pipe. All pipe joints shall be made watertight by the
use of couplings, gaskets, or caulking.
(d)
Acceptable pipe materials are corrugated polythylene, reinforced
concrete, and ductile iron. When necessary for stability, concrete
and ductile pipe shall be laid in a concrete bedding. Corrugated polythylene
pipe exposed to direct sunlight shall be made of ultraviolet-resistant
materials and protected by coating or shielding, or provisions for
replacement should be made as necessary. Connections of corrugated
polythylene pipe to less flexible pipe or structure must be designed
to avoid stress concentrations that could rupture the plastic.
(e)
Seepage control along pipes extending through embankments shall
be controlled by use of a filter and drainage diaphragm, unless it
is determined that antiseep collars will adequately serve the purpose.
[1]
The drain is to consist of sand meeting fine concrete aggregate
requirements (at least 15% passing through the No. 40 sieve, but no
more than 10% passing through the No. 100 sieve). If unusual soil
conditions exist, design engineers shall make a special design analysis.
The drain shall be a minimum of two feet thick and extend vertically
upward and horizontally at least three times to the pipe diameter,
and vertically downward at least 18 inches beneath the conduit invert.
The drain diaphragm shall be located approximately parallel to the
center line of the embankment. The drain shall be outletted at the
embankment downstream toe, preferably using a drain backfill envelope
continuously along the pipe where it exists in the embankment. Protecting
drain fill from the surface erosion will be necessary.
[2]
When antiseep collars are used in lieu of a drainage diaphragm,
they shall have a watertight connection to the pipe. Maximum spacing
shall be approximately 14 times the minimum projection of the collar
measured perpendicular to the pipe. Collar material shall be compatible
with the pipe materials. The antiseep collar(s) shall increase by
15% the seepage path along the pipe. When the antiseep collars are
used in lieu of a drainage diaphragm, the design engineers shall use
the following criteria to determine the size and number of antiseep
collars:
|
Let V
|
=
|
Vertical projection and minimum horizontal projection of the
antiseep collar in feet.
|
|
Let L
|
=
|
Length in feet of the conduit within the zone of saturation,
measured from the downstream side of the riser to the toe drain or
point where the phraetic line intercepts the conduit, whichever is
shorter.
|
|
Let n
|
=
|
Number of antiseep collars.
|
|
The ratio of the length of the seepage (L + 2nV) is to be at
least 1.15. Antiseep collars should be equally spaced along part of
the barrel within the saturated zone at distances of not more than
25 feet.
| ||
(f)
Closed circuit spillways designed for pressure flow must have
adequate antivortex devices. To prevent clogging of the conduit, an
appropriate trash guard shall be installed at the inlet or rise.
(g)
Emergency spillways convey the design flow safely past earth
embankments when the principal or auxiliary spillway is disabled.
Design engineers shall provide for an emergency spillway for each
basin.
[1]
Emergency spillways shall provide for passage of the design
flow at a safe velocity to a point downstream where the berm will
not be endangered. The maximum permissible velocity in the exit channel
shall be four feet per second, where only sparse vegetative cover
can be expected; where excellent vegetative cover and a vigorous sod
can be expected and maintained, the maximum permissible velocity is
six feet per second.
[2]
If chutes or drops are used for the principal or emergency spillways,
they shall be designed according to standards in the US Department
of Agriculture, Soil Conservation Service's Engineering Manual for
Conservation Practices (1984), or the US Department of Agriculture's
National Engineering Handbook, Section 5, Hydraulics; Section 11,
Drop Spillways; and Section 14, Chute Spillways; incorporated herein
by reference. The minimum capacity of a structural spillway shall
be that required to pass the peak flow expected from the design storm.
(h)
For excavated basin, provisions shall be made where needed for
a principal spillway, emergency spillway, and embankment in accordance
with the embankment and berm criteria described in this section.
[1]
Where soil conditions and safe maintenance practices allow,
side slopes of the excavated basin shall be stable and no steeper
than three horizontal to one vertical.
(i)
The material placed in the fill shall be free of detrimental
amounts of sod, roots, frozen soil, stones more than six inches in
diameter (except rock fills), and other objectionable material.
[1]
Drainfill shall be kept from being contaminated by adjacent
soil materials during placement by either placing it in a cleanly
excavated trench, or by keeping the drain a least one foot above the
adjacent earthfill.
[2]
Selected drainfill and backfill material shall be placed around
structure, pipe conduits, and antiseep collars at about the same rate
on all sides to prevent damage from unequal loading. Fill material
shall be placed and spread beginning at the lowest point in the foundation
and then bringing it up in continuous horizontal layers thick enough
that the required compaction can be obtained. The fill shall be constructed
in continuous horizontal layers. If openings or sectionalized fills
are required, the slope of the bonding surfaces between the embankment
in place and the embankment to be placed shall not be steeper than
the ratio of three horizontal to one vertical. The bonding surface
shall be treated the same as that specified for the foundation to
insure a good bond with the new fill.
[3]
The distribution and gradation of materials shall be such that
no lenses, pockets, streaks, or layers of material shall differ substantially
in texture of gradation from the surrounding material. If it is necessary
to use materials of varying texture and gradation, the more impervious
material shall be placed in the center and up stream parts of the
fill. If the zoned fills of substantially differing materials are
specified, the zones shall be placed according to lines and grades
shown on the drawings. The complete work shall conform to the lines,
grades and elevations shown in the drawings or as staked in the field.
[4]
The moisture content of the fill material shall be adequate
for obtaining the required compaction. Material that is too wet shall
be dried to meet this requirement, and material that is too dry shall
be wetted and mixed until the requirement is met. Construction equipment
shall be operated over each layer of fill to insure that the required
compaction is obtained. Special equipment shall be used if needed
to obtain the required compaction. If a minimum required density is
specified, each layer of fill shall be compacted as necessary to obtain
that density.
[5]
Fill adjacent to structures, pipe conduits, and drainfill or
antiseep collars shall be compacted to a density equivalent to that
of the surrounding fill by hand tamping or by using manually directed
power tampers or plate vibrators. Fill adjacent to concrete structures
shall not be compacted until the concrete has had time to gain enough
strength to support the load.
(j)
All permanent and temporary stabilization shall be applied pursuant
to the Standards for Soil Erosion and Sediment Control in New Jersey,
N.J.A.C. 2:90-1.
(k)
In a principal spillway, pipe materials shall conform to the
appropriate specifications. Antiseep collars shall be made of materials
compatible with that of the pipe and shall be installed according
to the manufacturer's instructions. It may be firmly and uniformly
bedded throughout its length, and shall be installed to the line and
grade shown on the drawings.
(l)
The mix design and testing of concrete shall be consistent with
the size requirements of the job. Mix requirements or necessary strength
shall be specified. The type of cement, air entrainment, slump, aggregate,
or other properties shall be specified as necessary. All concrete
is to consist of a workable mix that can be placed and finished in
an acceptable manner. Necessary curing shall be specified. Reinforcing
steel shall be placed as indicated on the plans and shall be held
securely in place during concrete placement. Subgrades and forms shall
be installed to line and grade, and the forms shall be mortar tight
and unyielding as the concrete is placed.
(m)
Foundation and embankment drains, if required, shall be placed
to the line and grade shown on the drawings. Detailed requirements
for drain material and any required pipe shall be shown in the drawing
and specifications for the job.
(n)
Concerning excavated basins, the compacted excavation shall
conform to the lines, grades and elevations shown on the drawing or
as staked in the field.
(o)
Concerning embankment and excavated berms, construction operations
shall be carried out so that erosion and air and water pollution are
minimized, and held within legal limits. All work shall be conducted
in a skillful manner. The completed job shall present a workmanlike
appearance.
[1]
Measures and construction methods that enhance fish and wildlife
values shall be incorporated as needed and practical. Ground cover
to control erosion shall be established as needed and practical. Fencing
shall be provided as needed.
(5)
Detention facilities in flood hazard areas, as follows:
(a)
Detention development must comply with all applicable regulations
under the Flood Hazard Area Control Act, N.J.S.A. 58:16A-50 et seq.
(6)
The following safety provisions shall apply to stormwater management
basins and parts thereof:
(a)
Trash racks shall be installed at the intake to the outlet from
the stormwater management basin if the intake has a diameter of 12
inches or greater.
(b)
Trash racks shall be designed to have parallel bars with no
greater than six-inch spacing. The spacing 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)
Any outlet structure with an overflow grate must have the grate
secured but removable for emergencies and maintenance. Grate spacing
shall be no greater than two inches across the smallest dimension.
(e)
Trash racks and overflow grates shall be constructed and installed
to be rigid, durable, and corrosion-resistant and shall be designed
to withstand a perpendicular live loading of 300 lbs/ft. sq.
(f)
Every outlet structure of a basin shall have escape provisions
in or on the structure. Freestanding outlet structures may be excluded
at the discretion of the approving authority.
(g)
Safety ledges shall be constructed on the slopes of all new
retention basins with a permanent pool of water deeper than 2 1/2
feet. Ledges shall be comprised of two steps, each four to six feet
in width, one located approximately 2 1/2 feet below the permanent
water surface, and the second located 1 1/2 feet above the permanent
water surface.
(h)
In new stormwater management basins, maximum interior slopes
for earthen dams, embankments, or berms shall not exceed three horizontal
to one vertical.
(i)
Municipalities or other specified agencies may grant a variance
or exception from these safety standards if they determine in writing
that such variance or exception will not constitute a threat to the
public safety.
(7)
Stormwater management facilities shall be regularly maintained
to insure they function at design capacity and to prevent health hazards
associated with debris buildup and stagnant water.
(a)
Maintenance and upkeep responsibility depend on ownership of
the facilities. If the drains, basins, and/or other features of the
stormwater system in the residential development are part of a public
drainage system, then the Township or an appropriate public entity
is responsible for maintenance and upkeep. If part or all of the residential
stormwater management system is privately owned, then the privately
owned portion of the system must be privately maintained, unless the
municipality or other appropriate public agency agrees to assume responsibility
for the facilities. The terms of the agreement shall be in a form
satisfactory to the Municipal Attorney and may include but are not
limited to maintenance easements, personal guaranties, deed restrictions,
covenants and bonds.
(b)
In cases where there is common ownership of property that is
not part of a public-owned drainage system, a homeowners' association
or similar permanent entity may be established as the agent responsible
for upkeep, absent an agreement with the Township or other appropriate
public entity.
A.
In addition to addressing water quantity generated by development,
a stormwater management system shall also prevent, to the greatest
extent feasible, an increase in nonpoint pollution.
B.
Stormwater management shall provide for the control of a water quality
design storm. The "water quality design storm" shall be defined as
the one-year frequency S.C.S. Type III, twenty-four-hour storm of
1.25 inches of rain falling uniformly in two hours.
(1)
In dry detention basins, provisions shall be made to ensure
that the runoff from the water quality design storm is retained, such
that not more than 90% will be evacuated prior to 18 hours. The retention
time shall be considered a brim-drawdown time and therefore shall
begin at the time of peak storage. The retention time shall be reduced
in any case that would require an outlet size diameter of three inches
or less. Therefore, three-inch-diameter orifices shall be the minimum
allowed. This minimum is only for water quality outlets. If this minimum
outlet sizes does not allow for the detention times required, then
additional techniques shall be used to remove total suspended solids.
(2)
In permanent ponds or wet basins, the water quality requirements
of these rules shall be satisfied where the volume of permanent water
is at least three times the volume of runoff produced by the water
quality design storm.
(3)
Infiltration practices such as dry wells, infiltration basins,
infiltration trenches, buffer strips, etc., may be used to satisfy
this requirement, provided they produce zero runoff from the water
quality design storm and allow for complete infiltration within 72
hours.
(4)
Suitable best management practices can be found in the following
documents:
(a)
New Jersey Stormwater Quantity/Quality Management Manual, State
of New Jersey, Department of Environmental Protection, February 1981.
(b)
Stormwater and Nonpoint Source Pollution Control, Best Management
Practices Manual, State of New Jersey, Department of Environmental
Protection, Office of Land and Water Planning.
(c)
Technical Manual for Land Use Regulation Program, Bureaus of
Inland and Coastal Regulations, Stream Encroachment Permits, Revised
September 1995, State of New Jersey, Department of Environmental Protection.
(d)
Ocean County Demonstration Study, Stormwater Management Facilities
Maintenance Manual, June 1989, State of New Jersey, Department of
Environmental protection, Office of Land and Water Planning.
(e)
Any Phase II regional stormwater management plan.
