[HISTORY: Adopted by the Mayor and Council of the Borough of New
Providence 10-27-1975 as Ord. No. 75-23
(Ch. 28, Art. VIII, of the 1973 Code of Ordinances). Amendments noted where
applicable.]
A.
It is hereby found that certain areas within the Borough
of New Providence are subject to recurrent flooding, that such flooding endangers
life and damages public and private property and facilities, that all developments
contribute to the condition by increasing local storm runoff and erosion and
that the most appropriate method of alleviating such condition is through
regulation of such developments. It is therefore determined that the special
and paramount public interest in the control of storm drainage justifies the
regulation of storm drainage for the entire municipal area, as provided in
this chapter, which is in the exercise of the police power of the municipality,
for the protection of the persons and property of its inhabitants and for
the preservation of the health, safety and general welfare.
B.
Among the purposes of this chapter are to:
(1)
Prevent loss of life.
(2)
Protect the public health and promote public safety and
welfare.
(3)
Minimize losses and damages to public and private property
due to inundation and siltation caused by floodwaters and storm runoff.
(4)
Prevent installation of structures which cause increases
in flood heights and/or velocities, erosion and siltation.
(5)
Prevent increased volume and rate of surface runoff due
to development.
(6)
Reduce public expenditures for emergency operations,
evacuations and restorations.
(7)
Prevent damage to transportation and utility systems.
For the purposes of this chapter, unless the context clearly indicates
otherwise, the following words shall mean:
The bed and banks of a stream which convey the normal flow of the
stream that occurs most of the time.
The State Department of Environmental Protection, Division of Water
Resources.
Any man-made change to real estate, whether by construction, excavation
or change of any topographical feature or surface condition.
Sand, gravel, earth or other materials of any composition whatsoever
placed or deposited by any person or persons.
The susceptibility of a specific land use at a particular site to
damage by potential floods at that site, as well as increased off-site flooding
or flood-related damages caused by such land use.
That portion of the floodplain (floodway) not occupied or required
for the floodway in which land can be used, subject to detail analysis and
design and construction controls.
The relatively flat area adjoining the channel which has been or
may be hereafter covered by floodwater of the stream; also the area of inundation
occasioned by a one-hundred-year-frequency flood based on water surface profiles
and generally labeled as "floodway" in the flood report. "Floodplain" includes
the terms "channel," "floodway" and "flood hazard area."
The channel of a natural stream or man-made channel and portions
of the adjoining floodplain reasonably required to pass the active discharge
of a one-hundred-year-frequency storm with not more than one-foot rise in
water surface elevation above that called for by conditions existing on the
date of passage of this chapter.
Includes but is not limited to any structure, fill, excavation, channel
modification, rock, gravel, refuse or matter in, along, across or projecting
into any channel, watercourse or flood hazard area which may impede, retard
or change the direction of the flow of water either in itself or by catching
or collecting debris carried by such water or that is placed where the flow
or water might carry the same downstream to the damage of life or property.
A test designed to determine the ability of ground to absorb water.
The test shall be performed by a licensed professional engineer with proven
competency in the field of soils engineering and shall be in accordance with
acceptable engineering standards and practices. A detailed report of the test
shall be submitted to the Planning Board and Municipal Engineer for review.
Corporations, companies, associations, societies, firms, partnerships
and joint-stock companies, as well as individuals, the state and all political
subdivisions of the state or any agencies or instrumentalities thereof.
The portion of rainfall which becomes direct surface runoff.
Any storm drainage technique which retards or detains runoff, such
as a detention basin, parking lot storage, rooftop storage, porous pavement,
dry wells or any combination thereof.
Any assembly of materials above or below the surface of land or water,
including but not limited to buildings, fences, dams, levees, bulkheads, dikes,
jetties, embankments, wharves, piers, docks, landings, obstructions, pipelines,
causeways, culverts, roads, railroads, bridges and the facilities of any utility
or municipality.
A.
No construction or development shall take place within
the municipal boundaries unless a drainage site plan and any other required
information shall have been submitted to the Planning Board of the Borough
of New Providence for its review and approval.
B.
Construction and development resulting in three or fewer
new lots for one- or two-family structures shall be exempt from the provisions
of this chapter.
C.
Said site plan shall be drawn to a scale not smaller
than one inch equals 50 feet and shall show, in addition to the information
required under other ordinances, the following information:
(1)
The existing and proposed principal building or structure
and all accessory buildings or structures, if any.
(2)
The proposed finished grade elevations at the corners
of any structure or structures.
(3)
Existing topography and proposed grading at contour intervals
of two feet or less.
(4)
The lowest elevation subject to floodwaters within any
proposed structure after its completion.
(5)
The location, type and size of all existing and proposed
storm drainage facilities and other utilities servicing and to service the
premises in question.
(6)
The location, size and nature of all existing and proposed
drainage rights-of-way or easements and the location, size and description
of any lands to be dedicated to the municipality or county.
(7)
The layout and size of existing and proposed public streets.
(8)
The elevation of any existing or proposed pumping facilities.
(9)
The nature and extent of any construction alterations
or repairs.
(10)
The location of the proposed and existing buildings on
the site.
(11)
The location, size and nature of the entire lot or lots
in question and any contiguous lots owned by the applicant or in which the
applicant has a direct or indirect interest.
(12)
Proof of stream encroachment lines obtained from the
Department.
(13)
The extent of filling of the land, if any.
(14)
The location, type and size of all existing and proposed
erosion and siltation control measures, such as slope protection, soil stabilization,
sedimentation basins, sediment traps, headwalls, aprons and the like.
(15)
Any and all other information and data necessary to meet
any of the requirements of this chapter.
D.
In addition, where required by the Planning Board, the
developer shall furnish information relating to subsurface conditions, based
on percolation tests and soil borings or probes.
E.
In reviewing any proposed construction or development,
the Planning Board shall be reasonably assured that any structure, when built
or altered, can be occupied without peril to the health or safety of the occupant
and that the proposed land use:
(1)
Has an inherent low flood damage potential.
(2)
Either acting alone or in combination with existing or
future uses, does not unreasonably obstruct flood flows or increase flood
heights and/or velocities.
(3)
Does not affect adversely the water-carrying capacity
of any delineated floodway and/or channel.
(4)
Does not measurably increase local runoff and erosion.
(5)
Does not unduly stress the natural environment of the
floodplain or degrade the quality of surface or the quality and
quantity of groundwaters.
(6)
Does not require channel modification or relocation,
beyond that indicated by the proposal.
F.
The Planning Board shall act upon any site plan provided
for in Sec. IV within 45 days of the date of filing thereof or the date of
approval by the Department, whichever is later, or other extension of time
agreed to by the applicant. Failure of the Planning Board to act within the
time limit or limits shall be deemed a denial of any site plan submitted under
this chapter. Planning Board disapproval shall include findings upon any site
plan element found contrary to the provisions or intent of this chapter.
G.
No land area shall be developed by any person such that:
(1)
The volume and/or rate of stormwater runoff occurring
at the area is increased over what occurs there under existing conditions.
(2)
The drainage during and after development is increased
over what naturally occurs there.
(3)
Soil erosion during and after development is increased
over what naturally occurs there.
(4)
The natural drainage pattern of the area is significantly
altered.
H.
In order to duplicate, as nearly as possible, natural
drainage conditions, regulation and control of stormwater runoff and erosion
for any land area to be developed shall incorporate but shall not be limited
to the following:
(1)
Detention areas, which may be depressions in parking
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.
(2)
Rooftop storage though temporary impoundment and storage
of stormwater on flat or slightly pitched building rooftops by use of drain
outlets which restrict the stormwater runoff from the roof surface.
(3)
Any system of porous media, such as gravel trenches,
drained by porous wall or perforated pipe, which temporarily store and dissipate
stormwater through ground absorption.
(4)
Any combination of the above-mentioned techniques or
others which serve to limit stormwater runoff from a given site to what presently
occurs there.
I.
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 for the one-hundred-year storm in the area involved
and shall be equivalent to the rainfall excess, as previously defined. The
total rainfall which produced the one-hundred-year storm shall be determined
from the report of the Federal Insurance Administration, Type 15 Flood Insurance
Study, Borough of New Providence, New Jersey, 1973.
J.
The rainfall excess shall be computed for each site using
accepted, published runoff percentages which reflect land use and topography.
Acceptable runoff percentages currently in practice include but are not limited
to the following:
|
Land Use Type
|
Runoff Percentage
(total runoff = 1.0)
| ||
|---|---|---|---|
|
Business:
| |||
|
Downtown areas
|
0.70 to 0.95
| ||
|
Neighborhood areas
|
0.50 to 0.70
| ||
|
Residential:
| |||
|
Single-family areas
|
0.30 to 0.50
| ||
|
Multi-units, detached
|
0.40 to 0.60
| ||
|
Multi-units, attached
|
0.60 to 0.75
| ||
|
Residential (suburban)
|
0.25 to 0.40
| ||
|
Industrial:
| |||
|
Light areas
|
0.50 to 0.80
| ||
|
Heavy areas
|
0.60 to 0.90
| ||
|
Parks and cemeteries
|
0.10 to 0.25
| ||
|
Playgrounds
|
0.20 to 0.35
| ||
|
Railroad yard areas
|
0.20 to 0.40
| ||
|
Unimproved areas
|
0.10 to 0.30
| ||
|
Surface Type
|
Runoff Percentage
(total runoff = 1.0)
| ||
|---|---|---|---|
|
Streets
| |||
|
Asphaltic
|
0.70 to 0.95
| ||
|
Concrete
|
0.80 to 0.95
| ||
|
Brick
|
0.70 to 0.85
| ||
|
Drives and walks
|
0.75 to 0.85
| ||
|
Roofs
|
0.75 to 0.95
| ||
|
Lawns, sandy soil:
| |||
|
Flat, 2%
|
0.05 to 0.10
| ||
|
Average, 2% to 7%
|
0.10 to 0.15
| ||
|
Steep, 7%
|
0.15 to 0.20
| ||
|
Lawns, heavy soil:
| |||
|
Flat, 2%
|
0.13 to 0.17
| ||
|
Average, 2% to 7%
|
0.18 to 0.22
| ||
|
Steep, 7%
|
0.25 to 0.35
| ||
K.
The range of percentages for each land use and surface
type reflects difference in land slope, intensity of development, amount of
impervious surface and degree of ground saturation due to antecedent precipitation.
L.
The runoff percentages shall be determined for each site
for both existing and proposed conditions, and the difference in the two shall
be used to compute the volume of rainfall excess for design of stormwater
facilities.
M.
Existing downstream facilities may have been designed
for five-year-, ten-year- or fifteen-year-frequency rainfalls. The design
of any upland drainage facility shall include an analysis of these facilities
and provide sufficient on-site storage, detention and other controls to ensure
that a one-hundred-year-frequency storm shall not overtax these structures.
N.
In the case of detention facilities utilizing porous
media for ground absorption, such as drywells, porous pavement or the like,
the volume of the porous media shall be large enough to contain the 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 information in the
office of the Engineer. Provisions shall be made to contain overflow of such
systems on site or to surface drain the overflow in such a way as not to adversely
affect any other property.
O.
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 the maximum discharge rate of stormwater
runoff to what occurs at the site under existing conditions and shall discharge
in such a way as to not 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 and the roof shall be designed to provide maximum
protection against leakage. If earth berms or dikes are used to create the
impounding area, they shall adequately be stabilized and the slopes protected
with vegetation cover, paving or rip rap to protect against failure or breaching.
P.
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.
Q.
Stormwater detention facilities shall be maintained regularly
by the owner to ensure continual functioning of the systems at design capacity
and to prevent the health hazards associated with debris build up 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.
Stormwater detention facilities shall be maintained by the owner of the land
unless the responsibility has been accepted or assigned by deed, easement,
agreement or other legal vehicle to others, including the Borough of New Providence.
R.
Detention and sediment and erosion control facilities
shall be designed in conformance with the principles of Standards for Soil
Erosion and Sediment Control in New Jersey of the New Jersey State Soil Conservation
Committee and administered by the Somerset-Union Soil Conservation District,
except where the Planning Board, on the advice of the Municipal Engineer,
has determined that conditions peculiar to a certain site warrant exception.
S.
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.
Any person, firm or corporation who or which shall violate any provision
of this chapter shall be liable to a fine not exceeding $200 or to imprisonment
for a term not exceeding 90 days, or both, and each day in which such violation
continues shall constitute a separate violation or offense.
