In addition to the performance standards and design criteria
requirements of this chapter, the applicant shall comply with the
following water quality requirements of this article:
A. For water quality and streambank erosion, the objective is to design
low-impact site conditions and water quality BMPs to detain the proposed
conditions two-year, twenty-four-hour design storm to the existing
conditions one-year flow using the SCS Type II distribution. Additionally,
provisions shall be made (such as adding a small orifice at the bottom
of the outlet structure) so that the proposed conditions one-year
storm takes a minimum of 24 hours to drain from the facility from
a point where the maximum volume of water from the one-year storm
is captured (i.e., the maximum water surface elevation is achieved
in the facility). At the same time, the objective is not to attenuate
the larger storms in "no-detention" areas (District C) only. This
can be accomplished by configuration of the outlet structure not to
control the larger storms or by a bypass or channel to divert only
the two-year flood into the basin or divert flows in excess of the
two-year storm away from the basin. Where practicable, wet basins
shall be utilized for water quality control and shall meet the requirements
found in the Pennsylvania Stormwater BMP Manual as revised. Release
of water can begin at the start of the storm (i.e., the invert of
the water quality orifice is at the invert of the facility). The design
of the facility shall consider and minimize the chances of clogging
and sedimentation. Orifices smaller than three inches in diameter
are not recommended. However, if the design professional can provide
proof that the smaller orifices are protected from clogging by use
of trash racks, etc., smaller orifices may be permitted.
B. In selecting the appropriate BMPs or combinations thereof, the applicant
shall consider the following:
(2) Permeability and infiltration rate of the site soils.
(3) Slope and depth to bedrock.
(4) Seasonal high-water table.
(5) Proximity to building foundations and wellheads.
(7) Land availability and configuration of the topography.
(8) Peak discharge and required volume control.
(10)
Efficiency of the BMPs to mitigate potential water quality problems.
(11)
The volume of runoff that will be effectively treated.
(12)
The nature of the pollutant being removed.
(13)
Maintenance requirements.
(14)
Creation/protection of aquatic and wildlife habitat.
C. For areas within defined special protection subwatersheds, which
include exceptional-value (EV) and high-quality (HQ) waters, the applicant
shall evaluate nondischarge alternatives to the proposed discharge
and use an alternative that is environmentally sound and cost-effective
when compared with the cost of the proposed discharge. If a nondischarge
alternative is not environmentally sound and cost-effective, a new,
additional, or increased discharge shall use the best available combination
of cost-effective treatment, land disposal, pollution prevention and
stormwater reuse technologies. An applicant proposing a new, additional,
or increased discharge to high-quality or exceptional-value waters,
who has demonstrated that no environmentally sound and cost-effective
nondischarge alternative exists, shall demonstrate that the discharge
will maintain and protect the existing quality of receiving surface
waters.
D. The applicant shall consider the guidelines found in the references
specified in Appendix G for constructed wetlands, where proposed.
E. Stormwater runoff from hot spot land uses shall be pretreated.
F. The use of infiltration BMPs is prohibited on hot spot land use areas,
such as vehicle fueling stations, public works storage areas, recycling
facilities, fleet storage areas, facilities that make or store hazardous
materials, etc.
G. Streambank restoration projects shall include the following:
(1) No restoration or stabilization projects may be undertaken without
examining the fluvial geomorphology of stable reaches above and below
the unstable reach.
(2) Restoration project design must then consider maintenance of stability
in the adjacent stable reaches of the stream channel.
(3) An erosion and sediment control plan approved by the conservation
district must be provided by the applicant.
(4) All applicable state and federal permits must be obtained.
H. Biology shall be incorporated into the design of all wet basins in
accordance with the West Nile Virus guidance found in Appendix E.
I. To accomplish the above, the applicant shall submit original and
innovative designs to the Municipal Engineer for review and approval.
Such designs may achieve the water quality objectives through a combination
of BMPs (best management practices).
J. Buffers.
(1) In addition to the other restrictions of §
160-15, buffers shall be provided in accord with this §
160-15J.
(2) Where resource buffers overlap, the more restrictive requirements
shall apply.
(3) Preexisting lots or parcels/development in outer buffers. In the
case of legally preexisting lots or parcels (approved prior to the
effective date of this chapter) where the usable area of a lot or
parcel lies within an outer buffer area, rendering the lot or parcel
unable to be developed in accordance with the allowable use per municipal
zoning, the development may only be permitted by variance as approved
at the sole discretion of the municipality.
(4) Improvements to existing structures in outer buffers. The provisions of this §
160-15J do not require any changes or improvements to be made to lawfully existing structures in buffers. However, when any substantial improvement to a structure is proposed which results in a horizontal expansion of that structure, the improvement may only be permitted by waiver as approved at the sole discretion of the municipality.
(5) Wetlands and vernal pools.
(a)
Wetland identification. Wetlands shall be identified in accord
with the 1987 U.S. Army Corps of Engineers Manual for Identifying
and Delineating Wetlands and properly flagged and surveyed on-site
to ensure they are protected.
[1]
Wetlands in an artificial watercourse. Wetlands contained within
the banks of an artificial watercourse shall not to be considered
for buffer delineation purposes.
[2]
Wetlands in a natural watercourse: wetlands contained within
the banks of a natural watercourse, only the stream buffer shall apply.
(b)
Continuous wetland and vernal pool buffer delineation. A twenty-five-foot
inner buffer and twenty-five-foot outer buffer, measured perpendicular
to and horizontally from the edge of the delineated wetland or vernal
pond for a total distance of 50 feet, shall be maintained for all
wetlands and vernal ponds.
[1]
Inner buffer: measured perpendicular to and horizontally from
the edge of the delineated wetland or vernal pond, for a distance
of 25 feet.
[a] Stormwater conveyance required by the Township,
buffer maintenance and restoration, the correction of hazardous conditions,
stream crossings permitted by DEP and passive unpaved stable trails
shall be permitted. No other earth disturbance, grading, filling,
buildings, structures, new construction, or development shall be permitted.
[b] The area of the inner buffer altered by activities
permitted in accord with this section shall be minimized to the greatest
extent practicable.
[2]
Outer buffer: measured perpendicular to and horizontally from
the outer edge of the inner buffer for a distance of 25 feet, resulting
in a total buffer of 50 feet.
[a] Stormwater conveyance required by the municipality, buffer maintenance and restoration, the correction of hazardous conditions, stream crossings permitted by DEP, roads constructed to existing grade, unpaved trails, and limited forestry activities that do not clear-cut the buffer (e.g., selective regeneration harvest) in accord with a forestry management plan shall be permitted, provided no buildings are involved, and those activities permitted under §
160-15J(3) and
(4).
[b] No more than 20% of the cumulative outer buffer
on the subject parcel shall be altered by the activities permitted
in accord with this section.
[c] Isolated wetland. A twenty-five-foot inner buffer
shall be required on isolated wetlands. Isolated wetlands are wetlands
that are surrounded by uplands and do not have any apparent surface
water inlets or outlets.
(6) Lakes and ponds.
(a)
There is no outer buffer around lakes and ponds.
(b)
Lake and pond buffer delineation. A fifty-foot buffer measured
perpendicular to and horizontally from the edge of any water body
shall be maintained around any water body.
(c)
Permitted activities/development. Stormwater conveyance required
by the Township/buffer maintenance and restoration, the correction
of hazardous conditions, lakefront views, boat docks and unpaved trails
shall be permitted, provided no buildings are involved.
(d)
The area of the buffer impacted by activities permitted in §
160-15J(6)(c) shall not exceed 35% of the buffer on the subject parcel.
(7) Streams.
(a)
Stream buffer delineation. A twenty-five-foot inner buffer and
twenty-five-foot outer buffer measured perpendicular to and horizontally
from the top-of-bank on both sides of any stream, for a total distance
of 50 feet, shall be maintained on both sides of any stream.
(b)
Inner buffer: measured perpendicular to and horizontally from
the top-of-bank of the stream for a distance of 25 feet.
[1]
Stormwater conveyance required by the Township, buffer maintenance
and restoration, the correction of hazardous conditions, stream crossings
permitted by DEP, fish hatcheries, wildlife sanctuaries and boat launch
sites constructed so as not to alter the floodplain cross section,
and unpaved trails shall be permitted, providing no buildings are
involved. No other earth disturbance, grading, filling, buildings,
structures, new construction, or development shall be permitted.
[2]
The area of the inner buffer altered by activities permitted
in accord with this section shall be minimized to the greatest extent
practicable.
(c)
Outer buffer: measured perpendicular to and horizontally from
the outer edge of the inner buffer for a distance of 25 feet, resulting
in a total buffer of 50 feet.
[1]
Stormwater conveyance required by the municipality, buffer maintenance
and restoration, the correction of hazardous conditions, agricultural
activities, plant nurseries, parking lots constructed to existing
grade, temporary fairs and carnivals, accessory uses for residential
purposes, private sportsmen's club activities, athletic facilities,
orchards, wildlife sanctuaries, boat launch sites, roads constructed
to existing grade, stream crossings permitted by DEP and unpaved trails
and limited forestry activities that do not clear-cut the buffer (e.g.,
selective regeneration harvest) in accord with a forestry management
plan shall be permitted, provided no buildings are involved.
[2]
In areas of the outer buffer which are not wetlands, vernal
ponds, or slopes of more than 15%, stormwater management facilities
which improve water quality of stormwater discharge shall be permitted
unless prohibited by other Township or state requirements. No other
earth disturbance, grading, filling, buildings, structures, new construction,
or development shall be permitted.
[3]
No more than 20% of the cumulative outer buffer on the subject
parcel shall be altered by the activities permitted in accord with
this section.
(8) Riparian buffer design. The riparian buffer shall be designed using
native grasses, shrubs, and trees. Stormwater runoff entering the
buffer should first flow through dense native grasses; the runoff
should then flow through dense native shrubs; finally, the runoff
should flow through native trees and into the water body. Runoff flows
should not be concentrated and directed through buffers. Runoff should
be applied to the buffer as sheet flow. It is important to maintain
ground cover throughout the buffer consisting of grasses, shrubs,
leaves, logs, branches, and other natural debris to slow the velocity
of the runoff and allow the filtration and infiltration of runoff.
The design of proposed riparian buffers must be submitted to the Municipal
Engineer for approval.
(9) Buffer averaging. This section outlines the criteria for buffer averaging
on new and redevelopment sites. Buffer averaging can be utilized to
adjust the required buffer width, allowing some flexibility for site
development. Using buffer averaging, the width of the buffer can be
varied with the criteria stated in this chapter, so long as a minimum
average width of 50 feet is maintained.
(a)
Requirements and policies. The following criteria must be met
in order to utilize buffer averaging on a development site:
[1]
An overall average buffer width of at least 50 feet must be
achieved within the boundaries of the property to be developed. Stream
buffer corridors on adjoining properties cannot be included with buffer
averaging on a separate property, even if owned by the same property
owner.
[2]
The average width must be calculated based upon the entire length
of streambank that is located within the boundaries of the property
to be developed. When calculating the buffer length, the natural stream
channel should be followed.
[3]
Stream buffer averaging shall be applied to each side of a stream
independently. If the property being developed encompasses both sides
of a stream, buffer averaging can be applied to both sides of the
streams but must be applied to both sides of the stream independently.
[4]
The total width of the buffer shall not be less than 35 feet
at any location, except at approved stream crossings. Those areas
of the buffer having a minimum width of 35 feet can comprise no more
than 50% of the buffer length.
[5]
The entire length of the buffer shall consist of an inner zone,
as defined in this chapter, having a minimum width of 25 feet, and
an outer zone that has a variable width along its length to achieve
the minimum average width of at least 50 feet.
(b)
Areas where buffer averaging is prohibited. Buffer width averaging
is prohibited in developments that have, or will have after development,
the land uses listed below:
[1]
Slope protection areas, and areas that have slopes greater than
15% that are located within 50 feet of the stream to be buffered;
[2]
Landfills (demolition landfills, permitted landfills, closed-in
place landfills);
[4]
Commercial or industrial facilities that store and/or service
motor vehicles;
[5]
Agricultural facilities, farms, feedlots, and confined animal
feed operations;
[6]
Animal-care facilities, kennels, and commercial/business developments
or facilities that provide short-term or long-term care of animals;
or
[7]
Other land uses deemed by the municipality to have the potential
to generate higher-than-normal pollutant loadings.
(10)
Reduction of buffer width.
(a)
The required buffer width of 50 feet can be reduced to 35 feet
(with an inner buffer of 25 feet and an outer buffer of 10 feet) if
the Board of Supervisors, after consultation with the Municipal Engineer,
determines that the proposed riparian buffer must, as a minimum, meet
the buffer requirements described in § 160-15.1(8) and also
meet the following criteria:
[1]
The riparian buffer should have slopes of less than 5%.
[2]
The immediate land area draining to the buffer should also have
slopes of less than 5%.
[3]
The area contributing to the buffer should be less than 150
feet.
[4]
The stormwater runoff entering the buffer should have a velocity
less than 1.5 feet per second.
[5]
The contact time of the stormwater runoff in the buffer area
should be five minutes or greater.
(b)
Under no circumstances shall the buffer be less than 35 feet,
even if buffer averaging is used. Other factors that may be considered
by the Board of Supervisors and the Municipal Engineer in approving
a reduced buffer width include land use draining to the buffer, soil
type and infiltration characteristics, and water table depth.