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.