This part shall be known and may be cited as
the "Nether Providence Township Stormwater, Erosion and Sediment Control
Ordinance."
The purpose of the part is to regulate the modification
of the natural terrain, the alteration of drainage and the maintenance
of artificial structures and surfaces and to provide for certain accelerated
erosion and sedimentation control measures within Nether Providence
Township so as to assure and safeguard health, safety, ecology and
general welfare in Nether Providence Township.
It is the intent of this chapter to implement Title 25, Rules and Regulations, Part
1, Department of Environmental Resources, Subpart C, Protection of Natural Resources, Article
II, Water Resources, Chapter 102, Erosion Control, of the Clean Streams Law, the Pennsylvania Stormwater Management Act of 1978 and any other applicable state and local regulations.
The Board of Commissioners may require that
a landowner or developer provide reasonable corrective measures to
alleviate an existing off-site drainage problem which may be affected
by the proposed subdivision and/or land development. It shall be the
responsibility of the landowner or developer to obtain all drainage
easements of not less than 25 feet on, over or through other properties,
and the Township, its agents, workmen, servants and employees shall
be indemnified and held harmless from any liability.
Any subdivision and/or land development within
a Flood Control District shall comply with all provisions of the Township
Flood Control Ordinance.
The definitions of terms used in this chapter
shall be as follows. (See also the Subdivision and Zoning Ordinances
for additional applicable definitions.)
ACCELERATED EROSION
The removal of the surface of the land through the combined
action of man's activities and natural processes at a rate greater
than would occur because of the natural processes alone.
ALLUVIAL SOIL
Consisting of or formed from material such as gravel, sand,
silt or clay deposited by flowing water and showing little or no modification
of the original material by soils-forming processes.
ANTECEDENT CONDITIONS
The specified characteristics of the land surface (e.g.,
meadow) prior to a proposed disturbance or prior to a rainfall event
(e.g., amount of moisture in the soil). This "antecedent condition"
is the basis for calculating increases in runoff attributable to the
disturbance or storms which must be controlled.
ASSIMILATIVE CAPACITY
The total capacity of the seepage bed structure to absorb
stormwater by virtue of its volume of storage and its ability to percolate
water into the soil below. This is usually expressed in cubic feet.
BERM
A well-compacted earth fill ridge.
BEST MANAGEMENT PRACTICE (BMP)
BMP activities, facilities, measures or procedures used to
manage stormwater impacts from land development, to protect and maintain
water quality and groundwater recharge and to otherwise meet the purposes
of this chapter, including but not limited to infiltration, filter
strips, low-impact design, bioretention, wet ponds, permeable paving,
grassed swales, forested buffers, sand filters and detention basins.
[Added 3-11-2004 by Ord. No. 681]
CFS
A measurement of flow, cubic feet per second.
CISTERN
A reservoir or tank for storing water.
DBH
The diameter of a tree at breast height, usually measured
3.5 feet from the ground surface.
DESIGN STORM
The magnitude of precipitation from a storm event against
which stormwater management facilities shall be designed to protect,
measured in probability of occurrence (e.g., one-hundred-year storm)
and duration (e.g., twenty-four-hour).
DETENTION BASIN
A structure designed to retain or detain runoff in order
to increase the time of concentration or to reduce the maximum discharge
rate of runoff from a developed area.
DIVERSION TERRACE
A channel or ditch and a ridge constructed across a sloping
land surface, on the contour or with predetermined grades, to intercept
and divert surface runoff before it gains sufficient volume and velocity
to create harmful erosion.
DRAINAGE EASEMENT
A right-of-way granted to use private land to facilitate
the flow of water, within which the owner shall erect no permanent
structures but may use the land in any other way not inconsistent
with the grantee's rights.
EARTHMOVING ACTIVITY
Activity resulting in the movement of earth or stripping
of vegetative cover from the earth.
ENERGY DISSIPATER
A concrete or stone structure designed to reduce the velocity
and force of a concentrated stream of water.
EROSION
The wearing away of soil by action of wind, water or other
geological agents.
FIRST FLUSH
The initial flow of stormwater runoff [usually the first
one-half (1/2) inch] which washes most bacterial and chemical pollutants
from the land.
GROUND STABILIZATION FABRIC
A plastic material designed to prevent upward and downward
movement of soil or other solids while permitting water movement.
It is commonly used in road construction when water-saturated soil
could weaken the road base and surface.
GROUNDWATER RECHARGE
Replenishment of geological structures and rock or soil interstices
which have the capacity to store water.
HYDROLOGY
Properties, distribution and effects of water on the earth's
surface, in the soil and underlying rocks and in the atmosphere.
IMPERVIOUS SURFACES
Materials which are essentially impenetrable and thus unable
to absorb liquids.
INFILTRATION STRUCTURE
A structure designed to direct the flow of rain into storage
in geological structures, e.g., French drains, Dutch drains, seepage
pits.
PEAK DISCHARGE
The maximum rate of flow of water at a given point resulting
from a predetermined storm.
RELEASE RATE
A volume of flow being released from a detention structure
per specified unit of time (e.g., gallons per minute).
RETAINING WALLS
A stabilized structure of stone, concrete or treated wood
designed to prevent the erosion or collapse of a rock or earthfaced
cut or fill.
RETENTION BASIN
A reservoir, formed from soil or other material, which is
designed to permanently retain a certain amount of stormwater from
a catchment area and which may also be designed to temporarily detain
excess stormwater runoff from the catchment area. "Retention basins"
may also receive fresh water from year-round streams. Unlike detention
basins, "retention basins" always contain water, thus they are man-made
lakes or ponds.
RUNOFF COEFFICIENT
That portion of a total volume of water which can be expected
to flow off a particular surface.
SCS
The Soil Conservation Service, United States Department of
Agriculture.
SEDIMENT
Solid material, both mineral and organic, that is in suspension,
is being transported or has been moved from its site of origin by
water.
SEDIMENT BASIN
A retention or detention basin located and designed to retain
rock, sand, gravel, silt and other stormwater-transported material
through trapping, screening, settling, etc.
SEEPAGE PIT
A broad area of excavated earth filled with loose stone or
other particles to which surface water is directed for infiltration
into geological storage.
SEEPAGE TRENCH
A linear excavation of the earth filled with loose stone
or similar materials to which surface water is directed for infiltration
to geological storage.
SOIL-COVER COMPLEX METHOD
A mathematical method of runoff computation developed by
the Soil Conservation Service of the United States Department of Agriculture
which provides for accurate consideration of the effect of applied
conservation measures on runoff rates and volume.
SPRING
A place at which water flows or seeps from soil or rock.
STABILIZED SOIL
Soil which is not susceptible to erosion due to natural vegetation
or mechanical or artificial stabilization.
STORM SEWER
A pipe or conduit that carries intercepted surface runoff,
street wash and other wash water or drainage but excludes domestic
sewage and industrial wastes.
STORMWATER
Water which surfaces, flows or collects during and subsequent
to rain or snowfall.
STREAM
Any perennial current or flow of water, especially one running
along the surface of the earth.
STREAM, MAJOR
Any stream that is shown as a blue line on United States
Coast and Geodetic Survey Quadrant Maps.
SUMP
A low point in a roadway or drainage swale where stormwater
can potentially fill to a depth of one foot or more prior to overflowing
to a lower area.
SWALE (DRAINAGE)
A low-lying stretch of land, natural or man-made, which collects
or carries surface water runoff.
TOWNSHIP ENGINEER
A duly appointed employee or independent contractor performing
engineering services for the Township or such individual appointed
by the Commissioners to perform the duties and services designated
herein.
UNDERSTABILIZED SOIL
Soil subject to erosion due to lack of vegetation or inherent
nature of soil structure.
No permit shall be required for:
A. The construction of a driveway which does not at any
point vary from the surrounding grade by more than one foot or exceed
1,000 square feet in area.
B. The construction or maintenance of a septic tank or
associated drain field.
C. Any project that does not involve or affect a stream, channel or storm-sewer system as described in §
281-7, When permit required.
All applicants shall bear all costs of inspections
required hereunder and shall deposit with the Nether Providence Township
Treasurer such sum as the Board of Commissioners shall determine to
guarantee payment of the costs of such inspections. The costs of inspections
shall be at the rate charged by the Nether Providence Township Engineer.