Township of Fairview, PA Drainage and Stormwater Management

Applicants proposing activities regulated by or subject to this chapter that do not fall under the waiver criteria shown in Subsection I shall submit a drainage/stormwater management (hereinafter referred to as "D/SW") plan consistent with this section to the Township for review. The stormwater management criteria of this section shall apply to the total proposed development even if development is to take place in phases.

Where feasible under accepted best management practices (BMPs), the applicant is required to find practicable alternatives to the surface discharge of stormwater, the creation of impervious surfaces, and the degradation of waters of the commonwealth and must maintain as much as possible the natural hydrologic regime.

The D/SW plan must be designed to ensure maintenance of the natural hydrologic regime, to promote groundwater recharge, and to protect groundwater and surface water quality and quantity.

Stormwater drainage systems shall be designed in order to permit unimpeded flow along natural watercourses, except as modified by stormwater management facilities or open channels consistent with this section.

Existing points of concentrated drainage that discharge onto adjacent property shall not be altered in any manner that could cause property damage without permission of the affected property owner(s) and shall be subject to any applicable discharge criteria specified in this section.

Areas of existing diffused drainage discharge, whether proposed to be concentrated or maintained as diffused drainage areas, shall be subject to any applicable discharge criteria in the general direction of existing discharge, except as otherwise provided by this section. If diffused drainage discharge is proposed to be concentrated and discharged onto adjacent property, the applicant must document that adequate downstream conveyance facilities exist to safely transport the concentrated discharge or otherwise prove that no erosion, sedimentation, flooding, or other impacts will result from the concentrated discharge.

(7)

Any stormwater management facilities regulated by this section that would be located in or adjacent to waters of the commonwealth or delineated wetlands, as determined through completion of a wetlands analysis and report as required by § 22-612, shall be subject to approval by the Pennsylvania Department of Environmental Protection (PADEP) through the joint permit application (JPA) or the environmental assessment approval process or, where deemed appropriate, by the PADEP general permit process. When there is a question as to whether wetlands may be involved, it is the responsibility of the applicant or his/her agent to show that the land in question cannot be classified as wetlands; otherwise, approval to work in the area must be obtained from PADEP.

(8)

Any proposed stormwater management facilities regulated by this section that would be located on state highway rights-of-way shall be subject to approval by the Pennsylvania Department of Transportation (PennDOT).

(9)

Minimization of impervious surfaces and infiltration of runoff through seepage beds, infiltration trenches, etc., is encouraged where soil conditions permit in order to reduce the size or eliminate the need for detention facilities or other structural stormwater BMPs.

(10)

Where feasible, stormwater runoff shall be pretreated for water quality prior to discharge to surface water or groundwater in accordance with accepted stormwater quality BMPs.

(11)

All regulated activities within the Township shall be designed, implemented, operated, and maintained to meet the purposes of this section through these two elements:

Erosion and sediment control during earth-disturbance activities (i.e., during construction); and

Water quality protection measures after completion of earth-disturbance activities (i.e., after construction), including operations and maintenance.

(12)

No regulated earth-disturbance activities within the Township shall commence until the requirements of this section are met.

(13)

Postconstruction water quality protection shall be addressed as required by Subsection C(5).

(14)

Operations and maintenance of permanent stormwater conveyance and management facilities and BMPs shall be addressed as required by Subsection G.

(15)

All BMPs used to meet the requirements of this section shall conform to the water quality requirements of the commonwealth and any more-stringent requirements as set forth by the Township.

(16)

In selecting the appropriate BMPs or combinations thereof, the applicant shall consider the following:

Total contributing area.

Permeability and infiltration rate of site soils.

Slope and depth to bedrock.

Seasonal high-water table.

Proximity to building foundations, wellheads, and septic systems.

Erodibility of soils.

Land availability and configuration of the topography.

Peak discharge and required volume control.

Stream bank erosion.

Efficiency of the BMPs to mitigate potential water quality problems.

The volume of runoff that will be effectively treated.

(l)

The nature of the pollutant(s) being removed.

(m)

Maintenance requirements.

(n)

Creation/protection of aquatic and wildlife habitat.

(o)

Recreational value.

(17)

The applicant may meet the stormwater management criteria through off-site stormwater management measures as long as the proposed measures are in the same subwatershed.

Plan content. Each development plan shall be accompanied by a D/SW plan. The D/SW plan shall consist of maps and a narrative prepared under the signature and seal of a professional registered in the Commonwealth of Pennsylvania qualified to perform such duties and responsible for the preparation of the D/SW plan. The D/SW plan shall include the following items:

A plan narrative, including a general statement of the project; the date the project is expected to begin and end; a description of existing and proposed conditions; a description of proposed permanent stormwater management techniques, including construction specifications of the materials to be used for stormwater management facilities; a general description of proposed non-point-source pollution controls; a discussion of ownership and maintenance of facilities; and conclusions. The plan narrative must also include a description of the effect of the project (in terms of runoff volumes and peak flows) on adjacent properties and on any existing Township stormwater collection system that may receive runoff from the project site. In addition, the plan narrative must include an operations and maintenance plan for stormwater management facilities.

A 7.5-minute USGS topographic quadrangle map, or equivalent, showing the project location and its total watershed(s), and additional maps, as necessary, to clearly show the delineation of all drainage areas, both on-site and off-site, used in all computations for all stormwater management facilities and all storm drainage facilities.

Project mapping identifying existing and proposed land use(s) and showing existing and proposed facilities and improvements, such as lots, streets, parking areas, drainage facilities, and erosion and sediment pollution control facilities; areas of cut and fill; limits of earth disturbance, including the type and amount of impervious area that would be added; soil type names and boundaries, including identification of the hydrologic soil group (HSG) designation of each; and stormwater management facilities.

Project mapping showing existing and proposed topographic features as follows:

Contours at two-foot intervals, except in areas where the slope is greater than 15%, in which case, the contour interval shall be five feet.

Boundary lines of the project area.

Existing streams, lakes, ponds, or other waters of the commonwealth within the project area.

Drainage on the project and adjoining properties, including floodplains, floodways, drainageways, and easements.

Other physical features, including flood hazard boundaries, stream buffers, and areas of natural vegetation to be preserved.

When infiltration measures such as seepage pits, beds, or trenches are used, the locations of existing and proposed septic infiltration areas and wellheads must be shown.

Continuous profiles for each reach of pipe plotted along with the hydraulic information pertinent to each reach within the system. This information shall include the pipe size and material, the Manning's Roughness Factor ("n"), the slope of the pipe, the design capacity, and the velocity at the design capacity.

Continuous profiles for each reach of open channel plotted along with the adjacent average ground and the hydraulic information pertinent to each reach within the system. This information shall include the type of channel lining, the Manning's Roughness Factor ("n"), the width of the channel bottom, the side slopes, the design capacity, and the water depth and velocity at the design capacity.

(7)

A note on the plan identifying designated water uses and water quality criteria, including high quality (HQ) and exceptional value (EV) waters, as identified in Chapter 93 of Title 24 of the Pennsylvania Code.

(8)

A note on the plan citing the operations and maintenance plan for stormwater management facilities and indicating the parties responsible for implementing the plan.

(9)

A note on the plan indicating the location and responsibility for maintenance of stormwater management facilities that would be located off site, if applicable. All off-site facilities shall meet the performance standards and design criteria specified in this section.

(10)

A statement, signed by the applicant, acknowledging that any revision to the approved D/SW plan must be approved by the Township and that a revised erosion and sediment control plan must be submitted to the York County Conservation District for a determination of adequacy.

(11)

The certification statement as provided in Appendix 13 of this chapter.[1] The certification statement must be signed, sealed, and dated by the responsible professional(s) after the last plan revision.

Editor's Note: Appendix 13 is included as an attachment to this chapter.

(12)

A declaration of adequacy and highway occupancy permit from PennDOT when utilization of a PennDOT storm drainage system is proposed.

(13)

Complete hydrologic, hydraulic, and structural computations for all drainage and stormwater management facilities, including identification and description of calculations, assumptions, and criteria used in the design of the facilities.

Design criteria.

General. The following design criteria are presented as the minimum acceptable standards available at the time this section was adopted. New and innovative procedures are encouraged and shall be permitted on a case-by-case basis by the Township Engineer. Design specifications for groundwater infiltration/recharge and water quality treatment facilities shall be in accordance with the latest editions of PADEP's Pennsylvania Stormwater Best Management Practices Manual and the Pennsylvania Association of Conservation Districts' Pennsylvania Handbook of Best Management Practices for Developing Areas or their successor publications pertaining to the same subject matter.

Drainage.

Design storm.

All drainage collection and conveyance facilities shall be designed to safely convey, without damage to the facility or other infrastructure, the twenty-five-year storm. More-stringent criteria may be required where the above criteria will aggravate existing problems or create new problems.

All drainage collection and conveyance facilities that are associated with a watercourse, drainageway, channel, or stream that conveys off-site runoff across a site shall be designed to safely convey, without damage to the facility or other infrastructure, the one-hundred-year storm and include drainage easements of sufficient width to accommodate the one-hundred-year water surface elevation.

Peak flow. The Rational Method shall be used for drainage areas up to 1/2 square mile. For drainage areas greater than 1/2 square mile, the Natural Resources Conservation Service (NRCS, formerly the Soil Conservation Service) soil cover complex method or other acceptable method, as approved by the Township Engineer, shall be used.

Rainfall. Design rainfall shall be determined using the latest edition of PennDOT's Intensity-Duration-Frequency (I-D-F) Curves for Region Four, as follows:

Rational Method. The appropriate time of concentration and return period shall be used to determine the rainfall intensity.

Soil cover complex method. The local twenty-four-hour rainfall distribution as determined from the latest edition of the National Oceanic and Atmospheric Administration's (NOAA's) Atlas 14, Precipitation-Frequency Atlas of the United States, shall be used with the following rainfall depths:

	Return Period	Twenty-Four-Hour Rainfall Depth (inches)
	2-year	2.90
	10-year	4.37
	25-year	5.44
	50-year	6.40
	100-year	7.50

Runoff coefficients.

Runoff coefficients for the Rational Method shall be determined by using Table 1 in Appendix 14 of this chapter.[2]

Editor's Note: Appendix 14 is included as an attachment to this chapter.

Runoff curve numbers for the NRCS soil cover complex method shall be determined using Table 2 in Appendix 14 of this chapter.[3]

Editor's Note: Appendix 14 is included as an attachment to this chapter.

Time of concentration. The methods found in Chapter 3 of the latest edition of Urban Hydrology for Small Watersheds, Technical Release TR-55, available from the U.S. Department of Agriculture, NRCS, shall be used to compute times of concentration. The length of flow path for sheet flow shall not exceed 100 feet and the length of flow path for shallow concentrated flow shall not exceed 1,000 feet.

Pipe design.

At a minimum, pipe capacities shall be computed using both the Manning Equation for full flow capacity and the Inlet Control Nomographs found in the latest edition of Hydraulic Design of Highway Culverts — Hydraulic Design Series #5, available from the U.S. Department of Transportation's Federal Highway Administration (FHWA).

Manning's Roughness Factors ("n") used in pipe design shall be as provided in the following table:

Type of Pipe		Manning's "n" Value
Concrete		0.012
Smooth lined plastic		0.011
Corrugated plastic		0.024
Smooth lined corrugated metal		0.012
Annular corrugated metal		0.027
Helical corrugated metal
	21" and under	0.019
	24" to 30"	0.020
	36" to 60"	0.021
	Over 60"	0.023
Annular or helical noncircular corrugated metal		0.024
Vitrified clay		0.012
Ductile iron		0.013

For inlets, the maximum headwater elevation must be less than the top of grate.

For culverts, the headwater/diameter ratio must be less than or equal to 1.25.

Complete outlet control calculations shall be required for special circumstances, such as high tailwater conditions, long runs of pipe, excessive bends and other losses, etc.

The minimum slope of any pipe shall be such that a minimum velocity of 2 1/2 feet per second shall be maintained when the pipe is flowing 1/4 full. Under no circumstances shall the pipe slope be less than 0.5%.

When pipe sizes change, the inside tops (crowns) of pipes shall be matched.

Roadside gutters and inlets.

The maximum allowable spread of water on streets for the twenty-five-year storm is half of a travel lane.

The maximum allowable gutter flow depth for the twenty-five-year storm is two inches.

The depth of flow across a street intersection for the twenty-five-year storm shall not exceed one inch.

Inlets shall be placed on both sides of the road at low points, at any change in horizontal or vertical direction of the storm sewer, and at all curb and road tangent intersections.

The maximum spacing of inlets shall be 450 feet or as necessary to prevent the allowable spread of water and/or gutter flow depth from being exceeded, whichever is less. Design calculations must be submitted supporting the spacing of all proposed inlets.

The paving surface adjacent to an inlet shall be constructed so as not to create a sudden dropoff or dip at the inlet.

Manholes may be substituted for inlets at locations where inlets would not serve a useful purpose.

Swales.

At a minimum, swale capacities and velocities shall be computed using the Manning Equation. Manning's Roughness Factors ("n") and maximum permissible velocities used in swale design shall be in accordance with the latest edition of PADEP's Erosion and Sediment Pollution Control Program Manual.

Swales shall be designed to convey the peak discharge from the one-hundred-year storm event. The resulting water surface elevations (limits) shall be identified on the D/SW plan.

Backwater calculations and other methods may be necessary for special conditions such as excessive bends and other losses, backwater conditions, etc.

All swales and channels shall include a minimum six inches of freeboard above the design flow depth.

The minimum longitudinal slope shall be 0.50%.

The maximum side slopes shall be 3H:1V for grass-lined swales and 2H:1V for rock-lined swales.

All grass-lined swales shall be provided with a minimum of four inches of topsoil. Swales shall be mulched and seeded with Formula B seed mixture in areas that will be mowed and Formula D seed mixture in areas with limited access that will not be mowed, in accordance with the latest edition of PennDOT Publication 408, § 804, or its successor publications pertaining to the same subject matter.

Bends in swales shall have adequate protection to avoid bank erosion and channel migration.

Any facilities that constitute water obstructions (i.e., bridges, culverts, stream enclosures, etc.) and any work involving wetlands governed by PADEP Chapter 105 regulations shall be designed in accordance with the requirements of the commonwealth and any more-stringent requirements as set forth by the Township.

Roadway crossings located within flood-prone areas, as defined by Chapter 151 of the Fairview Township Code, or as otherwise directed by the Township Engineer, must be able to safely convey runoff from the one-hundred-year design storm with a minimum of one foot of freeboard measured below the lowest point along the top of the roadway. For bridges, freeboard shall be measured below the low chord elevation of the bridge.

Drainage conveyance facilities to or exiting from stormwater management facilities (i.e., detention basins) shall be designed to convey the design flow to or from that structure.

Stormwater.

Design storm. The maximum peak rate of runoff for the proposed conditions shall not exceed the maximum peak rate of runoff for the existing conditions for the two-, ten-, twenty-five-, fifty-, and one-hundred-year storms. More-stringent criteria may be required where the above criteria will aggravate existing problems or create new problems.

Stormwater calculations. Stormwater calculations shall be determined using the following methods:

	Drainage Area (acres)	Method
	Less than 10	Modified Rational Method
	10 to 20	Modified Rational Method or NRCS soil cover complex method
	Greater than 20	NRCS soil cover complex method

Rainfall. Refer to Subsection C(2)(c).

Runoff coefficients.

For on-site contributing drainage areas, the land use/ground cover used in determining the peak rate of runoff for the existing conditions shall be considered as "meadow" in good condition. For off-site contributing drainage areas, the existing land use/ground cover shall be used.

Runoff coefficients for the Rational Method shall be determined by using Table 1 in Appendix 14 of this chapter.[4]

Editor's Note: Appendix 14 is included as an attachment to this chapter.

Runoff curve numbers for the NRCS soil cover complex method shall be determined using Tables 2A through 2C in Appendix 14 of this chapter.[5]

Editor's Note: Appendix 14 is included as an attachment to this chapter.

Time of concentration. Refer to § 260-35C(2)(e).

[Amended 1-25-2016 by Ord. No. 2016-1]

Routing. The design of any proposed stormwater management facility shall be verified by routing the proposed two-, ten-, twenty-five-, fifty-, and one-hundred-year hydrographs through the facility using the storage indication method or modified Puls Method.

Emergency spillway. Any stormwater management facility (i.e., detention basin) designed to store runoff and requiring a berm or earthen embankment shall be designed to provide an emergency spillway able to safely pass the peak rate of runoff from the post-development one-hundred-year storm with a minimum one foot of freeboard between the maximum (one-hundred-year) water surface elevation and the top of the berm/embankment. The use of inlets and pipes is prohibited for the emergency spillway.

The minimum depth of the spillway shall be two feet.

Design capacity and stability calculations for the emergency spillway crest and embankment channel must be provided with the D/SW plan to demonstrate the spillway will not erode during a one-hundred-year storm flow.

Riser pipe. The riser pipe shall be designed to withstand buoyancy forces if it becomes clogged.

Fencing. Stormwater detention basins shall be fenced with a six-foot-high fence that meets the following criteria: if the proposed fence is composed of horizontal and vertical members and the distance between the tops of the horizontal members is less than 45 inches, the horizontal members shall be located on the pond side of the fence. Spacing between vertical members shall not exceed 1 3/4 inches in width; maximum mesh size for chain-link fences shall be a one-and-one-fourth-inch square unless the fence is provided with slats fastened at the top or the bottom that reduce the openings to not more than 1 3/4 inches; the maximum vertical clearance between finished ground level and the fence shall be two inches or less, measured on the pond side of the fence; openings in the barrier shall not allow passage of a four-inch-diameter sphere.

Basin bottom. The minimum slope of any surface on the bottom of any basin shall be 1%. The use of forebays and permeable low-flow channels from any pipe or swale into the basin to the principal spillway, which contribute to infiltration/recharge and water quality treatment, is encouraged.

Side slope. The maximum side slope of stormwater detention basins shall be 4H:1V.

[Amended 1-25-2016 by Ord. No. 2016-1]

(l)

Embankments. Fill slopes and berms associated with detention basins shall be designed to be stable and shall have a minimum top width of eight feet and a maximum height of eight feet, measured from the invert of the outlet structure to the twenty-five-year design water surface elevation. Embankments shall also be designed using cutoff trenches, impervious cores, and anti-seep collars in order to prevent seepage and piping of the embankment material.

Basin embankments shall include a cutoff trench and impervious core from a depth of one foot below the toe of the interior basin slope to the twenty-five-year design water surface elevation, constructed of material having a coefficient of permeability less than or equal to 1310^-7 centimeters per second. This requirement is waived for embankments using undisturbed existing soils. The discharge pipe shall also be backfilled with relatively impervious soil. No stone backfill will be allowed unless anti-seep collars are provided.

A concrete (minimum six-inch-thick) or welded galvanized steel anti-seep collar(s) shall be placed around all basin discharge pipes to increase the seepage length along the pipe by 15% within the saturated zone of the pipe. The connection of the anti-seep collar to the discharge pipe shall be completely watertight. Anti-seep collar design calculations and details must be provided with the D/SW plan.

All fill material to be utilized in embankment areas shall be selected from the more-impervious materials available at the site and shall be compacted to a minimum of 95% of the materials' maximum dry density as determined by a Standard Proctor Test.

(m)

Basin outlet control structures. Basin outlet control structures shall consist of stainless steel orifice plates and mounting hardware, reinforced concrete risers and discharge pipes, and welded structural steel inlet grates with a bituminous coating. The use of plastic (i.e., PVC or polyethylene) pipe is prohibited for basin discharge pipes, except for small, single-family on-lot systems. For riser pipes where the designed water depth exceeds the height of the riser pipe by more than 0.4 times the riser pipe diameter, the riser shall have an anti-vortex device to prevent reduced capacity of the riser. Materials used for basin outlet control structure design shall be specified on the D/SW plan.

(n)

Lots adjacent to basins shall have a lowest floor elevation at least 1 1/2 feet higher than the one-hundred-year water surface elevation in the basin.

(o)

All stormwater runoff storage facilities must be located outside of flood-prone areas, as defined by Chapter 151 of the Fairview Township Code.

(p)

Access. All stormwater management facilities shall be accessible by vehicular means along stabilized access roads in order to allow for proper maintenance as required.

Groundwater recharge (infiltration/recharge/retention) requirements.

The ability to retain and maximize the groundwater recharge capacity of the area being developed is strongly encouraged. Design of infiltration stormwater management facilities shall consider groundwater recharge to compensate for the reduction in the recharge that occurs when the ground surface is disturbed or impervious surface is created. These measures are encouraged, particularly in HSGs A and B, and should be utilized wherever feasible. Soils used for the construction of basins shall have low erodibility factors ("K" factors).

It is recommended that roof runoff be directed to infiltration BMPs that may be designed to compensate for the runoff from parking areas. These measures should utilize any existing recharge areas.

Infiltration may not be feasible on every site due to site-specific limitations such as soil type. If it cannot be physically accomplished, then the design professional shall be responsible to demonstrate the reason(s).

Infiltration BMPs shall meet the following minimum requirements:

Infiltration BMPs intended to receive runoff from developed areas shall be selected based on suitability of soils and site conditions and shall be constructed on soils that have the following characteristics:

[a]

A minimum depth of 24 inches between the bottom of the BMP and the seasonal high-water table and/or bedrock (limiting zones).

[b]

An infiltration rate sufficient to accept the additional stormwater load and dewater completely as determined by field tests conducted by the applicant's design professional or as otherwise approved by the Township Engineer.

Infiltration BMPs receiving only roof runoff may be placed in soils having a minimum depth of 24 inches between the bottom of the facility and the limiting zone.

The size of the infiltration facility shall be based upon the following equation:

Re_v = (S x R_v x A)/12

Where:
	Re_v	=	Recharge volume (acre-feet)
	S	=	Soil-specific recharge factor (inches)
	R_v	=	Volumetric runoff coefficient
	A	=	Site area contributing to the recharge facility (acres)
And:

R_v = 0.05 + (0.009 x 1)

Where:
	I	=	Percent impervious area, (impervious coverage area/A) x 100
And:
S may be obtained based upon HSG as shown in the table below, recommended as general values by PADEP. More site-specific data may be utilized to determine recharge if justified by the design professional and approved by the Township Engineer.

	Hydrologic Soil Group (HSG)	Soil-Specific Recharge Factor (S) (inches)
	A	0.38
	B	0.25
	C	0.13
	D	0.06
	If more than 1 HSG is present at a site, a composite recharge volume shall be computed based upon the proportion of total site area within each HSG.

The recharge volume value derived from the method in Subsection C(4)(d)[3] is the minimum volume the applicant must control through an infiltration BMP facility. However, if a site has areas of soils where additional recharge volume can be achieved, the applicant is encouraged to infiltrate as much of the stormwater runoff from the site as possible.

The recharge volume provided at the site shall be directed to the most permeable HSG available, if feasible.

The recharge facility shall be capable of completely infiltrating the recharge volume within 48 hours.

A detailed soils evaluation of the project site may be required to determine the suitability of recharge facilities. The evaluation shall be performed by a qualified design professional and, at a minimum, address soil permeability, depth to bedrock, susceptibility to sinkhole formation, and subgrade stability. The general process for designing the infiltration BMP shall be:

Analyze HSGs as well as natural and man-made features within the site to determine general areas of suitability for infiltration practices. In areas where development on fill material is under consideration, conduct geotechnical investigations of subgrade stability; infiltration may not be ruled out without conducting these tests.

Provide field tests such as double-ring infiltrometer or hydraulic conductivity tests (at the level of the proposed infiltration surface) to determine the appropriate hydraulic conductivity rate. Percolation tests are not recommended for design purposes.

Design the infiltration facility for the required recharge volume (Re_v) based on field-determined capacity at the level of the proposed infiltration surface.

If on-lot infiltration structures are proposed by the applicant's design professional, it must be demonstrated to the Township that the soils are conducive to infiltration on the lots identified.

Extreme caution shall be exercised where infiltration is proposed in geologically susceptible areas, such as strip mine or limestone areas, in source water protection areas (SWPA), as defined by the Township or water service utility provider(s), and where salt or chloride (i.e., Township salt storage) would be a pollutant, since soils do little to filter this pollutant and it may contaminate the groundwater. The qualified design professional shall evaluate the possibility of groundwater contamination from the proposed infiltration/recharge facility and perform a hydrogeologic justification study if necessary.

Whenever a basin will be located in an area underlain by limestone, a geological evaluation of the proposed location shall be conducted to determine susceptibility to sinkhole formation. The design of all facilities over limestone formations shall include measures to prevent groundwater contamination and, where necessary, sinkhole formation.

The infiltration requirement in HQ (high quality) or EV (exceptional value) waters shall be subject to PADEP's Chapter 93 Antidegradation Regulations.

The Township may require the installation of an impermeable liner in detention basins where the possibility of groundwater contamination or sinkhole formation exists. A detailed hydrogeologic investigation may be required by the Township.

It shall be the applicant's responsibility to verify whether or not the site is underlain by limestone. The following note shall be included on all D/SW plans to be signed, sealed and dated after the last plan revision by the applicant's design professional:

"I hereby certify that, to the best of my knowledge, the proposed detention basin(s) is(are)/is(are) not underlain by limestone."

The Township may require the applicant to provide safeguards against groundwater contamination for land uses that may cause groundwater contamination should there be a mishap or spill.

(l)

Infiltration facilities may be used in conjunction with other innovative or traditional BMPs, stormwater control facilities, and nonstructural stormwater management alternatives.

(m)

Additional erosion and sediment control design standards and criteria are recommended to be applied where infiltration facilities are proposed. They shall include the following:

Areas proposed for infiltration facilities shall be protected from sedimentation and compaction during the construction phase to maintain maximum infiltration capacity.

Infiltration facilities shall not be constructed nor receive runoff until the entire drainage area contributory to the facility has achieved final stabilization.

(n)

It is strongly encouraged that proposed infiltration BMPs be determined in consultation with the Township Engineer for appropriateness and acceptability.

Water quality requirements.

The applicant shall comply with the water quality requirements of this section.

No regulated earth-disturbance activities within the Township shall commence until approval by the Township of a plan that demonstrates compliance with postconstruction water quality requirements of the commonwealth.

BMPs shall be designed, implemented, and maintained to meet water quality requirements of the commonwealth and any other more-stringent requirements as determined by the Township.

Developed areas shall provide adequate storage and treatment facilities necessary to capture and treat stormwater runoff. The recharge volume computed under Subsection C(4)(d)[3] may be a component of the water quality volume if the applicant chooses to manage both components in a single facility. If the recharge volume is less than the water quality volume, the remaining water quality volume may be captured and treated by methods other than infiltration/recharge BMPs.

The required water quality volume is the storage capacity needed to capture and treat stormwater runoff produced by "P" inches of rainfall (90% rule) from the developed areas of the site. The following calculation formula shall be used to determine the water quality volume of storage required:

WQ_v = (P x R_v x A)/12

Where:
	WQ_v	=	Water quality volume (acre-feet)
	P	=	1.95 inches (twenty-four-hour storm volume representing 90% of annual rainfall for PennDOT Region 4)
	R_v	=	Volumetric runoff coefficient
	A	=	Site area contributing to the water quality volume storage facility (acres)

	And:
	R_v = 0.05 + (0.009 x I)

	Where:
		I	=	Percent impervious area, (impervious coverage area/A) x 100

Water quality volume shall be designed as part of a stormwater management facility that incorporates water quality BMPs as a primary benefit of using that facility.

For areas within defined special protection subwatersheds that include EV (exceptional value) and HQ (high quality) waters, the temperature and quality of water and streams shall be maintained through the use of temperature-sensitive BMPs and stormwater conveyance systems.

Inlets constructed within Township rights-of-way shall include a twelve-inch sump for the collection and removal of sediments, with small weep holes provided in the bottom of the inlet to prevent standing water for long periods of time.

Water quality inlets and/or inserts shall not be permitted within Township rights-of-way.

It is strongly encouraged that proposed water quality BMPs be determined in consultation with the Township Engineer for appropriateness and acceptability.

Easements.

Easements shall be provided for all drainage and stormwater facilities in consultation with the Township Engineer.

The minimum width of such easements shall be 25 feet. Additional width may be required by the Township Engineer depending on the purpose and use of the easements.

Wherever possible, such easements shall be offset from side or rear lot lines or along the front lot lines. Easements for pipe shall be centered on the pipe.

A drainage easement shall be provided where a subdivision and/or land development is traversed by a watercourse, drainageway, channel, or stream. The width of the easement will be determined in consultation with the Township Engineer. The easement will conform substantially with the line of the watercourse, drainageway, channel, or stream. The width will be adequate to preserve the unimpeded flow of natural drainage or to widen, deepen, relocate, improve, or protect such drainage facilities or to install a storm sewer. Under no circumstances shall the easement be less than 25 feet. Access easements shall also be required.

Easements that do not follow property lines shall be identified by metes and bounds.

No person, firm, corporation, or other entity shall block, impede the flow of, alter, construct any structure, or place any other improvement in any stormwater easement. A note stating these restrictions shall be added to the plan.

The applicant shall create a separate easement agreement for all off-site stormwater easements that shall be executed, notarized, and filed with the Recorder of Deeds contemporaneous with the filing of the final subdivision and/or land development plan. With respect to on-site stormwater easements, the applicant shall place a note on the deed for each lot fully describing the easement or, alternatively, shall create a separate easement agreement for each lot subject to the easement. A note stating these easement agreement requirements shall be provided on the plan.

Construction standards.

General. Following are the minimum acceptable construction standards. Other standards will be considered on a case-by-case basis by the Township Engineer.

Drainage and stormwater.

Pipe.

Pipes shall be constructed in accordance with the specifications as set forth in the latest edition of PennDOT Publication 408 and applicable construction standards or their successor publications pertaining to the same subject matter.

Pipes, trenching, and backfill shall be in accordance with the specifications as provided in Appendix 16, Drawing No. 1.[6]

Editor's Note: Appendix 16 is included as an attachment to this chapter.

Pipe thickness and reinforcement shall be in accordance with approved engineering calculations.

[Amended 1-25-2016 by Ord. No. 2016-1]

Pipe sizes shall be in accordance with that shown on approved drawings. Minimum pipe size for drainage facilities shall be 18 inches in diameter for on-site collection. Pipes utilized for conveyance of off-site flows shall have a minimum size of 18 inches. All pipes shall be reinforced concrete pipe or HDPE plastic pipes. Overflow pipes used in stormwater BMPs shall be sized per the PA BMP Manual.

[Amended 1-25-2016 by Ord. No. 2016-1]

Pipes shall be constructed and set to line and grade as shown on approved drawings. Under no circumstances shall the pipe slope be less than 0.5%.

Pipes shall be provided with a minimum of one foot of cover between the top of pipe and the proposed finished grade in unpaved areas. The top of pipe shall be a minimum of six inches below the bottom of the pavement subgrade in paved areas. All pipes under a cartway or under driveways shall be backfilled with 2A aggregate only.

[Amended 1-25-2016 by Ord. No. 2016-1]

All pipe outlets shall be discharged to natural or man-made waterways and shall be provided with reinforced concrete endwalls or flared end sections. Polyethylene flared-end sections are prohibited. All pipe outlets shall be discharged to natural or man-made waterways. All upstream pipe endwalls shall be provided with reinforced concrete endwalls or concrete flared end sections.

[Amended 1-25-2016 by Ord. No. 2016-1]

(Reserved)[7]

Editor’s Note: Former Subsection D(2)(a)[8], regarding headwalls and endwalls of pipes, was repealed 1-25-2016 by Ord. No. 2016-1.

[9]

All pipe outlets shall be provided with an erosion-resistant material to accommodate the anticipated velocity and discharge of stormwater as designed.

[10]

Underdrains or pavement base drains shall be provided at low points, cut sections, poorly drained areas, and/or other areas which, in the opinion of the Township Engineer, are required to provide adequate subsurface drainage to protect the integrity of the roadway. Underdrains or pavement base drains shall have a minimum diameter of four inches and be connected to inlets with five-inch-minimum precast holes.

[Amended 1-25-2016 by Ord. No. 2016-1]

Inlets.

Inlets shall be constructed in accordance with the specifications as set forth in the latest edition of PennDOT Publication 408 and as detailed on the latest edition of drawing RC-34M of PennDOT Publication 72M — Standards for Roadway Construction, or their successor publications pertaining to the same subject matter.

Unless otherwise required by the Township Engineer, inlet tops shall be precast concrete top units with an eight-inch hood and shall be compatible with the type and height of curbing installed.

All inlets over five feet in depth, as determined from finished grade to the bottom of the inlet, shall be provided with steps for accessibility.

All inlets shall have weep holes placed at the appropriate elevations to completely drain the subgrade prior to placing the base course and surface course.

Inlets shall be inspected by the Township Engineer or his designated agent after completion of all work.

All inlets in paved areas shall have bicycle-safe grates.

Inlets in designated areas, identified by the Township Engineer, shall have a minimum one-foot sump under the pipe invert and two one-inch holes in the inlet bottom to drain the inlet of all water.

[Amended 1-25-2016 by Ord. No. 2016-1]

Where required by the Township Engineer, at all low points in curbed sections, swales and easements shall be provided behind the curb and through the adjacent properties to channelize and direct any overflow of water away from structures and buildings. The swale should be designed to accommodate a flow equal to that being collected by the inlets at the low point plus any additional drainage that may be directed to or collected by the swale itself.

Manholes.

Manholes shall be constructed in accordance with the specifications as set forth in the latest edition of PennDOT Publication 408 and as detailed on the latest edition of drawing RC-39M of PennDOT Publication 72M — Standards for Roadway Construction, or their successor publications pertaining to the same subject matter.

An opening with a minimum inside diameter of 30 inches shall be provided for access to the manhole.

Manholes shall be inspected by the Township Engineer or his designated agent after completion of all work.

Manhole covers shall be the bolt-down type.

[Added 1-25-2016 by Ord. No. 2016-1]

Miscellaneous structures and facilities. Miscellaneous structures and facilities shall be constructed in accordance with the latest editions of PennDOT Publication 408 and PennDOT Publication 72M — Standards for Roadway Construction, where applicable, or their successor publications pertaining to the same subject matter.

Other approvals. Compliance with this section does not preclude the need to obtain other permits and approvals as required by Fairview Township, York County, the York County Conservation District, the Commonwealth of Pennsylvania, the Federal Government, and other agencies. Other permits and approvals may include but not be limited to an erosion and sediment pollution control plan, National Pollutant Discharge Elimination System (NPDES) permit, water obstruction and encroachment permit, dam safety permit, submerged lands license agreement, approvals under §§ 401 and 404 of the Clean Water Act, and others. The most stringent of all pertinent requirements shall apply.

As-built plans. Upon completion of all required improvements and prior to release of the performance bond, the applicant shall submit as-built plans showing the actual location, dimension, and elevation of all drainage and stormwater management facilities included in the approved D/SW plan. In addition, the plans shall include a note certifying that the resultant grading, drainage and stormwater management facilities, and erosion and sediment control measures, including vegetative stabilization, are in conformance with the approved D/SW plan and specifications. Deviations from the approved D/SW plan and specification must be requested, along with justification for the request, and approved by the Township prior to construction. The applicant's design professional shall certify that the construction of the drainage and stormwater management facilities was completed in accordance with the D/SW plans and specifications approved by the Township. The plans shall note all deviations from the approved D/SW plan and specifications. The as-built plans and an explanation of any discrepancies with the approved plan shall be submitted to the Township for final approval. In no case shall as-built plans be submitted until the Township receives a copy of an approved declaration of adequacy and/or highway occupancy permit from PennDOT, NPDES permit, and any other applicable permits or approvals. The above permits and approvals must be based on the as-built plans.

Ownership and maintenance of storm drainage facilities. Prior to the granting of final approval by the Board of Supervisors, the applicant, as required by the Board of Supervisors, shall provide for and establish an organization for the ownership and maintenance of said facilities as provided herein and in accordance with the standards set forth below:

The applicant shall provide for and establish an organization for the ownership and maintenance of drainage facilities that are for the mutual benefit of all lots within the subdivision and/or land development, and such organization shall not be dissolved nor shall it dispose of drainage facilities owned by it by sale or otherwise (except to an organization conceived and established to own and maintain the drainage facilities).

The organization for the ownership and maintenance of drainage facilities shall be a nonprofit homeowners' organization operating under recorded land agreements that are covenants running with all the land encompassed within the development and shall be governed according to the following regulations:

The organization is organized by the developer and operating with financial subsidization by the developer, if necessary, before the sale of any lots within the development.

Membership in the organization is mandatory for all purchasers of lots therein and their successors.

The organization shall be responsible for maintenance of said drainage facilities and insurance and taxes on drainage facilities owned by the organization, and documents establishing the organization and the covenants running with the land shall authorize the organization to collect from its members amounts sufficient to comply with its obligations hereunder.

The members of the organization shall be required to share equitably in the costs of maintaining and developing drainage facilities in accordance with the terms set forth in the documents establishing the organization and the covenants running with the land.

The organization shall have or hire adequate staff to administer common facilities and maintain the drainage facilities.

The Board of Supervisors shall retain the right to review and approve the Articles of Incorporation or other documents creating the organization, all bylaws, and all declaration of covenants, conditions, and restrictions of the homeowners' organization as the same relate to the responsibility for ongoing ownership and maintenance. Additionally, the Township shall have a right of access and inspection of drainage facilities.

In the event that the organization established to own and maintain drainage facilities or any successor organization shall, at any time, fail to maintain the drainage facilities in reasonable order and condition in accordance with the development or subdivision plan, the Township may serve written notice on such organization or its members, or on the residents and owners of the development, setting forth the manner in which the organization has failed to maintain the drainage facilities in reasonable condition; and said notice shall include a demand that such deficiencies of maintenance be cured within 30 calendar days thereof and shall state the date and place of a hearing thereon, which shall be held within 14 calendar days of the notice. At such hearing, the Township may modify the terms of the original notice as to the deficiencies and may give an extension of time within which the same shall be cured. If the deficiencies set forth in the original notice or the modifications thereof shall not be cured within said 30 calendar days, or any extension thereof, the Township, in order to preserve the taxable values of the properties within the development and prevent the drainage facility from becoming a public nuisance, may enter upon said drainage facility and maintain the same for a period of one year. Said entry and maintenance shall not vest in the public any rights to use the drainage facilities except when the same are voluntarily dedicated to the public by the residents and owners. Before the expiration of said year, the Township shall, upon its initiative or upon the request of the organization, theretofore be responsible for the maintenance of the drainage facility and call a public hearing upon notice to such organization or to the residents and owners of the development, at which hearing such organization or the residents and owners of the development shall show cause why such maintenance by the Township shall not, at the election of the Township, continue for a succeeding year. If the Township shall determine that such organization is ready and able to maintain said drainage facilities in reasonable condition, the Township shall cease to maintain said drainage facilities at the end of said year. If the Township shall determine such organization is not ready and able to maintain said drainage facilities in a reasonable condition, the Township may, at its discretion, continue to maintain such drainage facilities during the next succeeding year and, subject to a similar hearing and a determination, in each year thereafter. The decision of the Township in any such case shall constitute a final administrative decision subject to judicial review.

The costs of maintenance and all other costs incurred by the Township, including but not limited to attorney fees, court costs, filing fees, engineering fees, and other expenses incurred by the Township in conjunction with the performance of maintenance under this section, shall be assessed ratably against the properties within the development and shall become a lien on said properties. The Township, at the time of entering on said drainage facilities for the purpose of maintenance, shall file a notice of such lien in the Office of the Prothonotary of York County, Pennsylvania, upon the properties affected by the lien within the development.

Prohibitions.

Prohibited discharges.

No party in the Township shall allow, or cause to allow, stormwater discharges into the Township's separate storm sewer system that are not composed entirely of stormwater, except as provided in Subsection H(1)(b), and for discharges allowed under a state or federal permit.

Discharges that may be allowed, based on a determination by the Township that the discharge(s) does not significantly contribute to pollution to surface waters of the commonwealth, are:

Discharges from firefighting activities, including training exercises.

Potable water sources, including dechlorinated water line and fire hydrant flushings.

Irrigation drainage.

Routine external building washdown that does not use detergents or other compounds.

Air-conditioning condensate.

Water from individual residential car washing.

Water from crawl space pumps.

Uncontaminated water from foundation or footing drains and sump pumps.

[9]

Flows from riparian habitats and wetlands.

[10]

Lawn watering.

[11]

Pavement wash waters where spills or leaks of toxic or hazardous materials have not occurred (unless all spill material has been removed) and where detergents or other compounds are not used.

[12]

Dechlorinated swimming pool discharges.

[13]

Uncontaminated pumped groundwater.

In the event that the Township determines that any of the discharges identified in Subsection H(1)(b) significantly contribute to pollution of waters of the commonwealth, or is so notified by PADEP, the Township will notify the responsible party to cease the discharge.

Upon notice provided by the Township under Subsection H(1)(c), the discharger will have a reasonable amount of time, as determined by the Township, to cease the discharge consistent with the degree of pollution caused by the discharge.

Nothing in this section shall affect a discharger's responsibilities under state and federal law.

Prohibited connections.

The following connections are prohibited, except as provided in Subsection H(1)(b):

Any drain or conveyance, whether on the surface or subsurface, that allows any nonstormwater discharge, including sewage, process wastewater, and wash water, to enter the separate storm sewer system and any connections to the storm drain system from indoor drains and sinks.

Any drain or conveyance connected from a commercial or industrial land use to the separate storm sewer system that has not been documented in plans, maps, or equivalent records and approved by the Township.

Roof drains.

In order to promote overland flow and infiltration of stormwater where advantageous to do so, roof drains shall not be connected to sanitary or storm sewers, streets, or roadside swales.

Roof drains shall discharge to infiltration areas or vegetative BMPs to the maximum extent practicable.

Exception.

When it is necessary to connect directly to storm sewers, streets, or swales, such connections may be permitted on a case-by-case basis as determined by the Township. The property owner shall bear all risk of casualty loss and all other liability and shall indemnify the Township from such risks.

Alteration of BMPs.

No party shall modify, remove, fill, landscape, or alter any existing stormwater management facility or BMP, as identified on the approved D/SW plan, unless it is part of an approved maintenance program, without the written approval of the Township.

No party shall place any structure, fill, landscaping, or vegetation in a stormwater management facility or BMP, as identified on the approved D/SW plan, that would limit or alter its function without the written approval of the Township.

Waivers.

Stormwater management facilities with direct discharge to the Yellow Breeches Creek or the Susquehanna River may be waived in order to facilitate drainage prior to stream flooding.

Any proposed activity regulated by or subject to the restrictions of this chapter that would result in less than 1,000 square feet of new, additional, or replaced impervious coverage, or in the case of earth disturbance only, less than 5,000 square feet of disturbance, shall not be required to provide on-site stormwater management facilities, provided that the increase in runoff for a twenty-five-year storm event will not adversely affect downstream properties. This shall be indicated on the plan with a note. Development that is planned to occur in stages or phases must be considered in its entirety for purposes of determining exemption. No more than one waiver will be granted for any cumulative property or project based on the effective date of this section.

[Amended 1-25-2016 by Ord. No. 2016-1]

A waiver from the requirements of this section shall not relieve the applicant from implementing such measures as are necessary to protect public health, safety, and property.

A waiver from the requirements of this section shall not relieve the applicant from meeting the special requirements for watersheds draining to identified HQ (high quality) and EV (exceptional value) waters and SWPAs (source water protection areas).

A waiver from the requirements of this section may be granted for emergency maintenance work performed for the protection of public health, safety, and welfare. A written description of the scope and extent of any emergency work performed shall be submitted to the Codes Enforcement Officer within two working days of the commencement of the activity. If the Township finds that the work is not an emergency, then the work shall cease immediately, and the requirements of this section shall be addressed as applicable.

A waiver from the requirements of this section may be granted for any maintenance of an existing stormwater management facility that is conducted in accordance with plans and specifications approved by the Township Engineer and Codes Enforcement Officer.

(7)

Even though the applicant may be granted a waiver from this section, he/she is not relieved from complying with other regulations.

Inspections.

Schedule of inspections.

The Township Engineer or Township's designee shall be permitted to inspect all phases of the installation of the permanent stormwater management facilities and BMPs.

The Township Engineer or Township's designee shall be permitted to inspect all phases of the site development work in progress to ensure compliance with erosion and sediment control requirements. Inspection functions under this section may be delegated by the Township to another entity if such agreement is entered into by the Township.

During any of the work, if the Township Engineer or the Township's designee determines that the permanent stormwater management facilities of BMPs are not being installed in accordance with the approved drainage plan, the Township shall revoke any existing Township permits and/or issue a stop-work order until a revised drainage plan is submitted and approved as specified in this section.

Right of entry.

Upon presentation of proper credentials, duly authorized representatives of the Township may enter at reasonable times upon any property within the Township to inspect the implementation, condition or operation of the stormwater management facility and stormwater BMPs in regard to any aspect governed by this section.

Stormwater management facility and BMP owners and operators shall allow persons working on behalf of the Township ready access to all parts of the premises for the purpose of determining compliance with this section.

Persons working on behalf of the Township shall have the right to temporarily locate on any stormwater management facility or BMP in the Township such devices as are necessary to conduct monitoring and/or sampling of the discharges from such BMP.