A.
The applicant shall provide the Engineer with sufficient
information to determine whether or not the proposed development will
conform to Borough runoff control details and stormwater detention
facility design criteria.
B.
In the judgment of the Borough Engineer, the proposed
development shall substantially conform to the standards and design
criteria set forth in this article.
No site in the Borough shall be developed so
that:
A.
The rate of stormwater runoff occurring at the site
is increased over what occurs there under existing conditions.
B.
The drainage of adjacent areas is adversely affected.
C.
Soil erosion during and after development is increased
over what naturally occurs there.
D.
Soil absorption and groundwater recharge capacity
of the site is decreased below what occurs under existing conditions.
E.
The natural drainage pattern of the area is significantly
altered.
In order to duplicate as nearly as possible
natural drainage conditions, the regulation and control of stormwater
runoff and erosion for any land area to be developed shall be through
on-site water detention and/or ground absorption systems, which include
but are not limited to the following:
A.
Detention areas, which may be depressions or lots
of areas, excavated basins, basins created through use of curbs, stabilized
earth berms or dikes or any other form of grading which serves to
temporarily impound and store water.
B.
Rooftop storage, through temporary impoundment and
storage of stormwater or slightly pitched building rooftops by use
of drain outlets which restrict the stormwater runoff from the roof
surface.
C.
Dry wells or leaching basins, which control stormwater
runoff through ground absorption and temporary storage.
D.
Porous asphaltic pavement, which preserves the natural
ground absorption capacity of a site and provides a subsurface reservoir
for temporary storage of stormwater.
E.
Any system of porous media, such as gravel trenches
drained by porous walls or perforated pipes, which temporarily stores
and dissipates stormwater through ground absorption.
F.
Any combination of the above-mentioned techniques
which serves to limit stormwater runoff from a given site to what
presently occurs there.
G.
Preservation of natural vegetation.
A.
Stormwater detention facilities shall be designed
to contain an amount equal to the increase in volume of runoff which
would result from development of any site. The volume of runoff shall
be computed on the basis of the total rainfall which produced the
flood of record for the area involved and shall be equivalent to the
rainfall excess, as previously defined. The total rainfall which produced
the flood of record shall be determined from accurate local records
of the United States Department of Commerce, Natural Weather Service,
or by calculations using accepted engineering techniques.
B.
The rainfall excess shall be computed for each site
using accepted, published runoff coefficients, such as found in Urban
Hydrology for Small Watersheds, Technical Release No. 55, Engineering
Division, Soil Conservation Service, United States Department of Agriculture,
January 1955, and may be modified by the Borough Engineer. The range
of coefficients for each land use and surface type reflects differences
in land slope, intensity of development, amount of impervious surface
and degree of ground saturation due to antecedent precipitation.
C.
The runoff coefficients shall be determined for each
site for both existing and proposed conditions, and the differences
in the two shall be used to compute the volume of rainfall excess
for design of stormwater detention facilities. The volume for design
is equal to the depth of the rainfall excess multiplied by the area
of the site. If any such facility will contain water under normal
conditions, the amount so contained shall not be counted in calculating
the capacity required for the detention of water for the design storm.
Rainfall intensity shall be as recommended by the Borough Engineer.
D.
In the case of detention facilities utilizing porous
media for ground absorption, such as dry wells, porous pavement or
the like, the volume of the porous media shall be large enough to
contain the total volume of rainfall excess within the voids. Ground
absorption systems shall be used only where the infiltration rate
of the receiving soil is acceptable as determined by percolation tests
and soil borings or as determined by the Borough Engineer. Provisions
shall be made to contain overflow of such systems on site or to surface-drain
the overflow of such systems on site or to surface-drain the overflow
in such a way as not to adversely affect any other property.
E.
If detention facilities utilizing surface impoundment,
such as detention basins or rooftop storage, are used, sufficient
volume to fully contain the total volume of rainfall excess shall
be provided. The outlets of such facilities shall be designed to limit
the maximum discharge rate of stormwater runoff to what occurs at
the site under existing conditions and shall discharge in such a way
as not to adversely affect any other property. If rooftop storage
is proposed, the weight of the impounded water on the roof shall be
accounted for in the structural design of the building, and the roof
shall be designed to provide maximum protection against leakage. If
berms or dikes are used to create the impounding area, they shall
be adequately stabilized and the slopes protected with vegetative
cover, paving or riprap to protect against failure or breaching.
F.
If a combination of different stormwater detention
techniques is used, the combined volume of the systems shall be large
enough to fully contain the total volume of rainfall excess.
G.
Stormwater detention facilities shall be constantly maintained by the owner to ensure continual functioning of the systems at design capacity and to prevent the health hazards associated with building debris and stagnant water. In no case shall water be allowed to remain in any facility long enough to constitute a mosquito-breeding, disease or any other type of health problem, unless approved as a multifunction facility to include water, such as a pond. If the land or stormwater detention facility or facilities are proposed to be dedicated to the Borough and said dedication is accepted by the Borough Council, the procedures for the construction, dedication and acceptance and maintenance of such facilities set forth in Article III, Subdivision Review and Approval, including but not limited to performance and maintenance bonds, inspections, etc., shall govern.
H.
Detention and sediment and erosion control facilities
shall be designed in conformance with the Standards for Soil Erosion
and Sediment Control in New Jersey of the New Jersey State Soil Conservation
Commission, as approved by the Borough Engineer or the Hunterdon Soil
Conservation District under agreement, except where the Borough Engineer
has determined that conditions peculiar to a certain site warrant
exception.
I.
Sediment and erosion control measures shall be installed
prior to any other site development, shall apply to all aspects of
the proposed development and shall be in operation during all stages
of development. Increased runoff and sediment resulting from modified
soil and surface conditions caused by the proposed development shall
be minimized and, where possible, retained on site.
Prior to the granting of any site development
approval, the applicant may be required to enter into an agreement
with the Borough, in a form satisfactory to the Borough Attorney,
requiring the installation and maintenance by the applicant and the
applicant's successors in interest of such improvements on or to the
site or imposing such limitations upon the development thereof as
are deemed necessary by the Planning Board for implementing the standards
and criteria set forth in this article. Improvements installed or
maintained in violation of such limitations shall be corrected at
the expense of the applicant or the applicant's successors in interest.
The agreement shall also provide for inspection annually and after
each major flood by the Borough Engineer or his agent at the expense
of the applicant and the applicant's successors in interest and for
the undertaking, by the applicant and successors, of such corrective
measures as are shown by such inspection to be required for the proper
functioning of the facilities.
Improvements on the site related to stormwater
control, during and upon completion of their construction, shall be
subject to inspection and approval by the Borough Engineer or his
agent, who shall be notified by the applicant at least 24 hours prior
to the start of construction. No underground installation of such
improvements shall be covered until inspected and approved. Approval
or reasons for withholding approval shall be given promptly. If work
proceeds without such approval or not in compliance therewith, the
Borough Engineer, in addition to any other remedies available to the
Borough, may issue an order requiring immediate cessation of the affected
work and prohibiting resumption thereof until approval is obtained
or noncompliance corrected.
Prior to the acceptance by the Borough of any
stormwater facilities, the developer's engineer shall certify that
said facilities were constructed in accordance with the approved plan.
