As used in this Article:
Shall mean the conditions which exist upon application for
a building permit or a subdivision or site plan approval.
Shall mean that portion of the flood hazard area outside
the floodway.
Shall mean the total area being delineated as being below
the 100-year storm high-water mark elevation. The "flood hazard area"
shall consist of the floodway and the flood fringe area.
Shall mean the elevation of the 100-year storm high-water
mark of the nearest point on the center line of the stream adjacent
to the area in question.
Shall mean the greatest flood in the Borough of Rockleigh
for which accurate records are available.
Shall mean the channel of a natural stream and adjacent areas
required to carry floodwater of flood flow of any natural stream and/or
an area delineated by the Department of Environmental Protection.
[1973 Code § 88-13.1]
[1973 Code § 88-13.2]
a.
Specific Permitted Land Uses. Agriculture including residential lawns
and gardens but not including structures or paved areas.
b.
All Other Uses. All other uses are prohibited.
c.
Stream Encroachment Permits. The Construction Official shall not
issue a permit for any permitted use in a flood hazard area until
a stream encroachment permit has been issued by the Department of
Environmental Protection.
[1973 Code § 88-13.3]
a.
No building permit shall be granted for any improvement outside any
flood hazard area except where one of the following conditions is
met, as determined by the Construction Official:
1.
The application is for an alteration or addition to or the construction
of a single one-family residence on a single lot not contiguous with
another lot of the same ownership.
2.
The application is for an alteration or addition or the construction of a building on land which is part of a major subdivision which meets the standards of § 32-7.5 of Chapter 32, Land Subdivision; that provisions for detention of the additional stormwater runoff from such improvement were provided by the subdivider; and that construction proposals provide proper connections to such detention systems and do not exceed their capacity. Where verification of the above is required by the Construction Official, he shall submit the application to the Borough Engineer, who shall provide a written report stating either that the permit may be granted because it meets the standards of this Article or that the permit shall be denied and for what reasons.
3.
Where the Construction Official determines the improvement will increase
the runoff, he shall submit the detailed drawings to the Borough Engineer,
who shall provide a written report stating that the permit may be
granted because it meets the standards of this Article or that the
permit shall be denied and for what reasons.
4.
For one-family dwellings for which site plan submissions are required to be made under Chapter 31, Site Plan Review, the following information shall be submitted in order to protect against adverse consequences for surface water drainage:
(a)
The existing surface drainage pattern as it affects the subject
property and all abutting properties.
(b)
Any proposed changes in the existing surface drainage pattern
which will result from the construction of the dwelling proposed for
the subject property, including any proposed changes on abutting properties.
(c)
The elevation of the street at each limit of the subject property
frontage.
(d)
The elevations of the finished garage floor and first floor
of the dwelling proposed for the subject property.
(e)
The proposed location of all roof leader drains.
(f)
The outer limits of all areas in which any proposed filling
or grading is proposed.
b.
Improvements within the flood fringe areas or which are located on
land which is one foot or less above the flood hazard design elevation
shall be subject to the following:
1.
Fill shall be no lower than one foot above the flood hazard design
elevation and shall extend as such for a distance of at least 15 feet
beyond the limits of any structure erected thereon.
2.
Structures shall be built so that the first floor and/or basements
are at a minimum of one foot above the flood hazard design elevation,
except that pavement and related site structures such as storm sewers,
manholes, curbing, etc., shall be set at grades to be approved by
the Borough Engineer.
3.
Floodproofing measures shall be consistent with the flood protection
elevation for the particular area, flood velocities, durations, rates
of rise, hydrostatic and hydrodynamic forces and other similar factors.
The applicant may be required to submit a plan or document certified
by a licensed professional engineer that the floodproofing measures
are consistent with the flood hazard design elevation and associated
flood factors. Any or all of the following floodproofing measures
may be required:
(a)
Anchorage to resist flotation and lateral movement.
(b)
Installation of watertight doors, bulkheads and shutters or
similar devices.
(c)
Reinforced walls to resist water pressures.
(d)
Use of paints, membranes or mortars to reduce seepage or water
through walls.
(e)
Addition of weight to structures to resist flotation.
(f)
Installation of pumps to lower water levels in structures.
(g)
Construction of water supply and waste treatment systems in
a manner which prevents the entrance of floodwaters.
(h)
Pumping facilities or comparable measures for the subsurface
drainage systems of buildings to relieve external foundation wall
and basement flood pressures.
(i)
Construction that resists rupture or collapse caused by water
pressure or floating debris.
(j)
Installation of valves or controls on sanitary and storm drains
which will permit the drains to be closed to prevent backup of sewage
or stormwaters into the structure. Gravity drainage of basements may
be eliminated by mechanical devices.
(k)
All electrical equipment panels, outlets and electrical appliances
shall be located at least four feet above the level of the flood hazard
design elevation to assure that they will not be subject to inundation
or flooding.
(l)
Storage facilities for chemicals, explosives, buoyant materials,
flammable liquids or other toxic or hazardous materials shall be situated
at least six feet above the flood hazard design elevation and shall
be floodproofed to prevent flotation of storage containers or damage
to storage containers which could result in the escape of toxic materials
into the floodwaters.
(m)
Use of construction materials which are resistant to water damage.
c.
The applicant shall provide all information deemed necessary by the
Construction Official and/or the Borough Engineer for their determination.
[1973 Code § 88-13.4]
a.
General Requirements. Land areas shall only be developed or improved
such that:
1.
The rate of stormwater runoff from the area is not increased over
that which occurs under existing conditions.
2.
The drainage characteristics of adjacent areas are not adversely
affected.
3.
Soil erosion during and after development is not increased over that
which occurs under existing conditions.
4.
Soil absorption and groundwater recharge capacity of the area is
not decreased below that which occurs under existing conditions.
5.
The natural drainage pattern of the area is not significantly disturbed.
b.
Permitted Detention Systems.
1.
Depressions in parking areas, excavations, basins created through
use of curbs, stabilized earth berms or dikes or other form of grading
which serves to temporarily and safely impound and store stormwater.
2.
Rooftops which temporarily and safely impound and store stormwater,
including drain outlets which restrict the rate of runoff from the
roof surface.
3.
Dry wells or leaching basins which control stormwater runoff through
ground absorption restricted outflow.
4.
Porous asphaltic pavement which preserves the natural ground absorption
rate of a site and provides a subsurface reservoir for temporary storage
of stormwater.
5.
Any system of porous media, such as gravel trenches drained by porous
wall or perforated pipe, which temporarily stores and dissipates stormwater
through ground absorption.
6.
Any combination of the above systems which limits stormwater runoff
from a given site to that which occurs under existing conditions.
c.
Design of Stormwater Detention Facilities.
1.
Stormwater detention facilities shall be designed to contain a volume
of water equal to the increase in volume of runoff which would result
from development of any site based upon the total rainfall which produced
the flood of record for the area involved. The total rainfall which
produced the flood of record shall be determined from records of the
United States Department of Commerce, National Weather Service.
2.
Rainfall Excess Computation.
(a)
The rainfall excess shall be computed using runoff coefficients
not less than the following:
|
Surface Type
|
Runoff Coefficients
|
|---|---|
|
Asphalt
|
0.95
|
|
Concrete
|
0.95
|
|
Roofs
|
0.95
|
|
Lawns, sandy soils:
| |
|
Flat, less than 2 percent
|
0.10
|
|
Average, 2 to 7 percent
|
0.20
|
|
Steep, 7 percent or over
|
0.25
|
|
Lawns, heavy soils:
| |
|
Flat, less than 2 percent
|
0.15
|
|
Average, 2 to 7 percent
|
0.25
|
|
Steep, 7 percent or over
|
0.35
|
|
Unimproved areas
|
0.20
|
(b)
Runoff coefficients for other surfaces shall be established
by the Borough Engineer.
3.
The runoff coefficients 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
detention facilities. The volume used for design of the detention
facilities shall be equal to the depth of the rainfall excess multiplied
by the area of the surface.
4.
Detention facilities which utilize porous media for absorption, such
as dry wells and porous pavement, shall be of such a size 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 in such a way as not to adversely affect any adjacent property.
5.
Detention facilities which utilize surface impoundment, such as depression
in parking areas, rooftops and diked areas, shall provide sufficient
volume to fully contain the total volume of rainfall excess. The outlets
of such facilities shall be designed to limit the maximum discharge
rate of stormwater runoff to that which occurs at the site under existing
conditions and shall discharge in such a way as to not adversely affect
adjacent property. If rooftop storage is proposed, the weight of the
water on the roof shall be provided for in the structural design of
the building, and the roof shall be designed to provide maximum protection
against leakage. Earth berms or dikes used to create an impounding
area shall be stabilized with the slopes protected with vegetative
cover, paving or riprap to protect against failure or breaching.
6.
If a combination of different stormwater techniques is used, the
system shall be adequate to fully control the total volume of rainfall
excess.
7.
Stormwater detention facilities shall be maintained by the owner
to ensure continual functioning of the systems as designed and to
prevent hazards associated with debris buildup and stagnant water.
Water shall not be allowed to remain long enough to constitute mosquito
breeding, disease or any other type of health problem. Easements shall
be provided to all detention facilities from public rights-of-way,
if required, so that such facilities are available to municipal authorities
for the purposes of determining if the facilities are properly maintained
and, where necessary, to maintain the facilities.
8.
Detention, 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 District.
9.
Facilities to control sediment and erosion shall be built prior to
any other site development and shall be in operation during all stages
of development. Increased runoff resulting from modified soil and
surface conditions caused by the proposed development shall be minimized
and, where possible, retained on the site. Increased erosion and sediment
resulting from construction at the proposed development will be prohibited.
