Township of Marshall, PA Chapter 165 Stormwater Management

[HISTORY: Adopted by the Board of Supervisors of the Township of Marshall 11-26-2018 by Ord. No. 461. Amendments noted where applicable.]

§ 165-101 Short title and statement of findings.

1. This Chapter shall be known and cited as the "Marshall Township Stormwater Management Ordinance".

2. Statement of findings. The governing body of the Marshall Township finds that:

A. Inadequate management of accelerated runoff of stormwater resulting from development throughout a watershed increases runoff volumes, flows and velocities, contributes to erosion and sedimentation, overtaxes the carrying capacity of streams and storm sewers, greatly increases the cost of public facilities to carry and control stormwater, undermines flood plain management and flood control efforts in downstream communities, reduces groundwater recharge, threatens public health and safety, and increases nonpoint source pollution of water resources.

B. A comprehensive program of stormwater management (SWM), including regulation of development and activities causing accelerated runoff, is fundamental to the public health, safety, and welfare and the protection of people of the Commonwealth, their resources, and the environment.

C. Stormwater is an important water resource that provides groundwater recharge for water supplies and supports the base flow of streams.

D. The use of green infrastructure (GI) and low impact development (LID) are intended to address the root cause of water quality impairment by using systems and practices which use or mimic natural processes to: 1) infiltrate and recharge, 2) evapotranspire, and/or 3) harvest and use precipitation near where it falls to earth. Green infrastructure practices and LID contribute to the restoration or maintenance of pre-development hydrology.

E. Federal and state regulations require certain municipalities to implement a program of stormwater controls. These municipalities are required to obtain a permit for stormwater discharges from their separate storm sewer systems under the National Pollutant Discharge Elimination System (NPDES) program.

§ 165-102 Purpose.

In order to protect the health, safety, and general welfare of the residents of the Township, as well as to protect, sustain, and enhance the surface and ground water resources of the Township, drainage and stormwater management practices shall be utilized as directed herein to achieve the following goals and objectives:

A. Accommodate site development and redevelopment in a manner that protects public safety and that is consistent with (or re-establishes) the natural hydrologic characteristics of each watershed and sustains ground water recharge, stream baseflows, stable stream channel (geomorphology) conditions, the carrying capacity of streams and their floodplains, ground water and surface water quality, and aquatic living resources and their habitats.

B. Reduce and minimize the volume of stormwater generated.

C. Protect natural infiltration and ground water recharge rates in order to sustain ground water supplies and stream baseflows.

D. Maintain runoff characteristics of the site after completion of development that are consistent with the carrying capacity and stable channel conditions of the receiving streams.

E. Ensure that the chemical, physical, and biological quality of ground and surface waters are protected by requiring appropriate management of stormwater pursuant to this Chapter.

F. Protect instream channels and geomorphology conditions of the receiving streams; protect their flood carrying capacity and aquatic habitats and to reduce instream erosion and sedimentation.

G. Reduce flooding impacts and prevent a significant increase in surface runoff rates and volumes, predevelopment to post-development, which could worsen flooding downstream in the watershed, enlarge floodplains, erode stream banks and create other flood-related health-welfare-property losses; in general, to preserve and restore the natural flood-carrying capacity of streams and their floodplains.

H. Protect adjacent lands from adverse impacts of direct stormwater discharges.

I. Ensure effective long-term operation and maintenance of all permanent stormwater management facilities.

J. Maintain natural drainage patterns and encourage the use of natural drainage systems.

K. Treat and release stormwater as close to the source of runoff as possible using a minimum of structures and maximizing reliance on natural processes.

L. Maintain the existing water balance in all watersheds, subwatersheds, and streams in the Township, and protect and/or restore natural hydrologic characteristics and habitats wherever possible throughout the watershed systems.

M. Address requirements of the Municipal Separate Storm Sewer System (MS4) National Pollution Discharge Elimination System (NPDES) Phase II Stormwater Regulations as applicable to the Township.

N. Reduce the impacts of runoff from existing developed sites undergoing redevelopment while encouraging development and redevelopment in urban areas and areas designated for growth.

O. Meet legal water quality requirements under applicable State law, including regulations at 25 Pa. Code Chapter 93.4a, as amended, to protect and maintain "existing uses" and maintain the level of water quality to support those uses in all streams, and to protect and maintain water quality in "special protection" streams.

P. Minimize the potential for accelerated erosion and sedimentation from Regulated Activities.

Q. Prevent scour, aggradation, degradation and erosion of stream banks and streambeds.

§ 165-103 Definitions.

ACCELERATED EROSION AND SEDIMENTATION

The removal of the surface of the land through the combined action of human activities and the natural processes, at a rate greater than would occur because of the natural process alone.

ACT 167

The Pennsylvania Storm Water Management Act, 32 P.S. § 680.1 et seq., as amended.

ACT 167 PLAN (or WATERSHED PLAN)

The plan for managing stormwater runoff throughout a designated watershed adopted by Allegheny County as required by the Pennsylvania Storm Water Management Act.

AGRICULTURAL ACTIVITY

The work of producing crops including tillage, land clearing, plowing, disking, harrowing, planting, harvesting crops, or pasturing and raising of livestock and installation of conservation measures. Construction of new buildings or impervious area is not considered an Agricultural Activity.

ACCD

The Allegheny County Conservation District or its successor.

ALLEGHENY COUNTY DEPARTMENT OF REAL ESTATE

The Department of Real Estate for Allegheny County or its successor.

ACHD

The Allegheny County Health Department or its successor.

ALLEGHENY COUNTY PLANNING AGENCY

The Allegheny County Department of Economic Development or its successor.

AASHTO

American Association of State Highway and Transportation Officials.

APPLICANT

A landowner, developer or other person who has filed an application for approval to engage in any regulated activity at a project site in the Township.

AQUIFER

A geologic formation, group of formations, or part of a formation that contains sufficient saturated, permeable material to yield useful quantities of ground water to wells and springs.

ATTENUATE

To reduce the magnitude of the flow rate by increasing the time it takes to release a specified volume of runoff (for example the one-year, 24-hour storm event). Attenuation is a method of reducing the peak flow rates for post development compared to the peak flow rates in predevelopment.

BASEFLOW

Portion of stream discharge derived from ground water; the sustained discharge that does not result from direct runoff or from water diversions, reservoir releases, piped discharges, or other human activities.

BEST MANAGEMENT PRACTICE (BMP)

Activities, facilities, designs, measures, or procedures used to manage stormwater impacts from regulated activities, to meet state water quality requirements, to promote groundwater recharge, and to otherwise meet the purposes of this Chapter. Stormwater BMPs are commonly grouped into one of two broad categories or measures: "structural" or "non-structural." In this Chapter, non-structural BMPs or measures refer to operational and/or behavior-related practices that attempt to minimize the contact of pollutants with stormwater runoff, whereas structural BMPs or measures are those that consist of a physical device or practice that is installed to capture and treat stormwater runoff. Structural BMPs include, but are not limited to, a wide variety of practices and devices, from large-scale retention ponds and constructed wetlands, to small-scale underground treatment systems, infiltration facilities, filter strips, low impact design, bioretention, wet ponds, permeable paving, grassed swales, riparian or forested buffers, sand filters, detention basins, and manufactured devices. Structural stormwater BMPs are permanent appurtenances to the project site.

BOARD OF SUPERVISORS

The Board of Supervisors of Marshall Township, Allegheny County, Pennsylvania.

CHANNEL

A natural or artificial watercourse that conveys, continuously or periodically, flowing water.

CLEAN STREAMS LAW

The Pennsylvania Clean Streams Law, 35 P.S. § 691.1 et seq., as amended.

CONCENTRATED STORM RUNOFF

Surface runoff from rainfall events, which converges and flows primarily through water conveyance features such as swales, gullies, waterways, channels or storm sewers and which exceeds the maximum specified flow rates of filters or perimeter controls intended to control sheet flow.

CONSERVATION DESIGN

A series of holistic land development design practices that maximize protection of key land and environmental resources, preserve significant concentrations of open space and greenways, evaluate and maintain site hydrology, and ensure flexibility in development design to meet community needs for complementary and aesthetically pleasing development. Conservation Design encompasses the following objectives: conservation/enhancement of natural resources, wildlife habitat, biodiversity corridors and greenways (interconnected open space); minimization of environmental impact resulting from a change in land use (minimum disturbance, minimum maintenance); maintenance of a balanced water budget by making use of site characteristics and infiltration; incorporation of unique natural, scenic and historic site features into the configuration of the development; preservation of the integral characteristics of the site as viewed from adjoining roads; and reduction in maintenance required for stormwater management practices. Such objectives can be met on a site through an integrated development process that respects natural site conditions and attempts, to the maximum extent possible, to replicate or improve the natural hydrology of a site.

CONSERVATION DISTRICT

A conservation district, as defined in Section 3(c) of the Conservation District Law (3 P.S. § 851(c)) that has the authority under a delegation agreement executed with DEP to administer and enforce all or a portion of the regulations promulgated under 25 Pa. Code 102.

CFS

Cubic feet per second.

DESIGN STORM

The magnitude and temporal distribution of precipitation from a storm event measured in probability of occurrence (e.g., a five-year storm) and duration (e.g., 24 hours), used in the design and evaluation of stormwater management systems, also see Return Period.

DETENTION or TO DETAIN

The prevention of, or to prevent, the discharge, directly or indirectly, of a given volume of stormwater runoff into surface waters by temporary storage.

DETENTION BASIN

An impoundment designed to collect and retard stormwater runoff by temporarily storing the runoff and releasing it at a predetermined rate. Detention basins are designed to drain completely shortly after any given rainfall event and are dry until the next rainfall event.

DEVELOPER

As defined in the Subdivision and Land Development Ordinance (Chapter 174).

DEVELOPMENT SITE (SITE)

See "Project Site."

DISCHARGE

To release of water from a project, site, aquifer, drainage basin or other point of interest (verb); the rate and volume of flow of water such as in a stream, generally expressed in cubic feet per second (volume per unit of time) (noun).

DISTURBED AREA

An un-stabilized land area where an Earth Disturbance is occurring or has occurred.

DITCH

An artificial waterway for irrigation or stormwater conveyance.

DRAINAGE AREA

That land area contributing runoff to a single point and that is enclosed by a ridge line.

DRAINAGE SYSTEM

All facilities and natural features used for the movement of stormwater through and from a drainage area, including, but not limited to, any and all of the following; conduits, pipes and appurtenant features: channels, ditches, flumes, culverts, streets, swales, gutters as well as all watercourses, water bodies and wetlands.

EARTH DISTURBANCE

A construction or other human activity which disturbs the surface of the land, including, but not limited to, clearing and grubbing; grading; excavations; embankments; road maintenance; building construction; the moving, depositing, stockpiling, or storing of soil, rock or earth materials.

EASEMENT

A right of use of a specified portion of land of another for a specified purpose.

ENGINEER

A professional engineer licensed as such in the Commonwealth of Pennsylvania.

EPA

Environmental Protection Agency or its successor.

EROSION

The wearing away of land surface by water or wind which occurs naturally from weather or runoff, but is often intensified by human activity.

EXISTING CONDITION

The dominant land cover during the five-year period immediately preceding a proposed Regulated Activity.

FEMA

Federal Emergency Management Agency or its successor.

FLOODPLAIN

Any land area susceptible to inundation by water from any natural source or delineated by applicable FEMA maps and studies as being a special flood hazard area.

FLOODWAY

The channel of the watercourse and those portions of the adjoining floodplains that is reasonably required to carry and discharge the 100-year flood. Unless otherwise specified, the boundary of the floodway is as indicated on maps and flood insurance studies provided by FEMA. In an area where no FEMA maps or studies have defined the boundary of the 100-year floodway, it is assumed—absent evidence to the contrary—that the floodway extends from the stream to 50 feet from the top of the bank of the stream.

FIRST ORDER STREAM

Upper-most perennial tributary in a watershed that has not yet confluenced with another perennial stream. The confluence of two first order streams forms a "second" order stream.

FOREST MANAGEMENT/TIMBER OPERATIONS

Planning and activities necessary for the management of forestland. These include timber inventory and preparation of forest management plans, silvicultural treatment, cutting budgets, logging road design and construction, timber harvesting, site preparation and reforestation.

FREEBOARD

Freeboard is the difference between the elevation of the design flow in the emergency spillway (usually the 100-year peak elevation) and the top elevation of the settled basin embankment (that is, top of berm). The minimum freeboard shall be one foot.

GROUND WATER

Water that occurs in the subsurface and fills or saturates the porous openings, fractures and fissures of underground soils and rock units.

HOTSPOTS

An area where land use or activities generate highly contaminated runoff, with concentrations of pollutants in excess of those typically found in stormwater.

HYDROGRAPH

A graph of discharge versus time for a selected point in the drainage system.

HYDROLOGIC SOIL GROUP (HSG)

Infiltration rates of soils vary widely and are affected by subsurface permeability as well as surface intake rates. Soils are classified into four HSGs (A, B, C, and D) according to their minimum infiltration rate, which is obtained for bare soil after prolonged wetting. The Natural Resources Conservation Service (NRCS) of the U.S. Department of Agriculture defines the four groups and provides a list of most of the soils in the United States and their group classification. The soils in the area of the development site may be identified from a soil survey report that can be obtained from local NRCS offices or conservation district offices. Soils become less pervious as the HSG varies from A to D.

HYDROLOGY

The study of the properties, distribution, circulation and effects of water on the Earth's surface, soil and atmosphere.

IMPERVIOUS COVER

See "Impervious Surface."

IMPERVIOUS SURFACE

A surface (area), which has been compacted or covered with a layer of material so that it is resistant to infiltration by water. It includes semi-pervious surfaces such as compacted clayey soils, as well as most conventionally surfaced streets, roofs, sidewalks, parking lots, and other similar surfaces. Net Increase of Impervious Surface refers to the difference between the existing impervious coverage and the total impervious surface proposed.

INFILTRATION

Movement of surface water into the soil, where it is absorbed by plant roots, evaporated into the atmosphere, or percolates downward to recharge ground water.

INTERMITTENT STREAM

A defined channel in which surface water is absent during a portion of the year, as ground water levels drop below the channel bottom.

INTENSITY

The depth of accumulated rainfall per unit of time.

KARST

A type of topography that is formed over limestone or other carbonate rock formations by dissolving or solution of the rock by water, and that is characterized by closed depressions, sinkholes, caves, a subsurface network of solution conduits and fissures through which ground water moves, and no perennial surface drainage features.

LAND DEVELOPMENT (DEVELOPMENT)

As defined in the Pennsylvania Municipalities Planning Code.

LANDOWNER

As defined in the Subdivision and Land Development Ordinance (Chapter 174).

LEVEL SPREADER

A low earthen berm constructed perpendicular to the direction of slope and extending across the width of the slope for the purpose of intercepting surface runoff and spreading it behind the berm to enhance infiltration and reduce erosion and runoff from the slope. The purpose of a level spreader is to prevent concentrated, erosive flows from occurring and to spread out stormwater runoff uniformly over the ground as sheet flow.

LOADING

The total amount (generally measured in pounds or kilograms per acre per year) of material (sediment, nutrients, oxygen-demanding material, or other chemicals or compounds) brought into a lake, stream or water body by inflowing streams, runoff, direct discharge through pipes, ground water, the air (aerial or atmospheric deposition) and other sources over a specific period of time (often annually).

LOW IMPACT DEVELOPMENT (LID)

Site design approaches and small-scale stormwater management practices that promote the use of natural systems for infiltration, evapotranspiration, and reuse of rainwater. LID can be applied to new development, urban retrofits, and revitalization projects. LID utilizes design techniques that infiltrate, filter, evaporate, and store runoff close to its source. Rather than rely on costly large-scale conveyance and treatment systems, LID addresses stormwater through a variety of small, cost-effective landscape features located on-site.

MAINTENANCE

The action taken to restore or preserve the as-built functional design of any facility or system.

MEADOW CONDITION

A natural groundcover with less than one viable tree of a DBH of six inches or greater per 1,500 square feet within 10 years of application; a cover condition for which SCS curve numbers have been assigned or to which equivalent rational method runoff coefficients have been assigned.

MS4

Municipal Separate Storm Sewer System.

MUNICIPALITIES PLANNING CODE (MPC)

The Pennsylvania Municipalities Planning Code, 53 P.S. § 10101 et seq., as amended.

MUNICIPALITY

Marshall Township, Allegheny County, Pennsylvania.

NOAA

National Oceanic and Atmospheric Administration or its successor.

NATIONAL POLLUTION DISCHARGE ELIMINATION SYSTEM (NPDES)

Created in 1972 under the Clean Water Act to authorize discharges to local receiving waters only pursuant to governmental permits, in an effort to reduce point source and non-point source pollutants.

NRCS

Natural Resources Conservation Service or its successor.

NEW DEVELOPMENT

Any activity regulated by this Chapter that is not considered a redevelopment as defined in this Chapter.

NON-STRUCTURAL STORMWATER MANAGEMENT PRACTICES

Passive, site design approaches or regulatory approaches that positively impact water quality and reduce or minimize the generation of stormwater runoff without requiring the construction of specific or discrete stormwater management control structures.

OPEN CHANNEL

Any natural or man-made watercourse or conduit in which water flows with a free surface.

OPEN VEGETATED CHANNEL

Also known as swales, grass channels, and biofilters. These systems are used for the conveyance, retention, infiltration and filtration of stormwater runoff.

PASTURE CONDITION

A ground cover of grassland or range with continuous forage for grazing and greater than 75% ground cover and lightly or only occasionally grazed; a cover condition for which the Soil Conservation Service curve numbers have been assigned or to which equivalent rational method runoff coefficients have been assigned.

PEAK DISCHARGE

The maximum rate of stormwater runoff from a specific storm event.

PACD

Pennsylvania Association of Conservation Districts.

PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL PROTECTION (PADEP)

The Department of Environmental Protection of the Commonwealth of Pennsylvania or its successor.

PENNSYLVANIA DEPARTMENT OF TRANSPORTATION (PENNDOT)

The Department of Transportation of the Commonwealth of Pennsylvania or its successor.

PERCOLATION RATE

The rate of movement of water under hydrostatic pressure through interstices of rock or soil. For stormwater analysis, it is typically measured as a distance per unit of time (e.g., inches per hour).

PERVIOUS AREA

Any area not defined as impervious.

PREDEVELOPMENT ASSUMPTION

The ground cover assumption used when analyzing the stormwater runoff characteristics of a drainage area prior to the proposed development.

PROJECT SITE

The specific area of land where any Regulated Activities in the Township are planned, conducted or maintained.

QUALIFIED DESIGN PROFESSIONAL

Any person licensed by the Pennsylvania Department of State or otherwise qualified by law to perform the work required by this Chapter, including a Professional Engineer, a Professional Landscape Architect, and a Professional Land Surveyor.

RAINFALL INTENSITY

The depth of accumulated rainfall per unit of time.

RATE

Volume per unit of time.

RECEIVING WATERS

Any water bodies, watercourses or wetlands into which surface waters flow.

RECHARGE

The replenishment of ground water through the infiltration of rainfall, other surface waters, or land application of water or treated wastewater.

REDEVELOPMENT

An existing, developed property and/or a graded, altered and compacted site (as of or after the date of adoption of this Chapter) that is proposed for reconstruction involving the demolition or partial demolition of the property.

REGULATED ACTIVITIES

Any Earth Disturbances or any activities that involve the alteration or development of land in a manner that may affect post construction stormwater runoff.

REGULATED EARTH DISTURBANCE ACTIVITY

Activity involving Earth Disturbance subject to regulation under 25 Pa. Code Chapter 92, Chapter 102, or the Clean Streams Law.

RELEASE RATE PERCENTAGE

The percentage of predevelopment peak rate of runoff from a watershed subarea (as delineated in the Act 167 watershed plan), which defines the allowable post-development peak discharge from any development site in that subarea.

RETENTION or TO RETAIN

The prevention of direct discharge of stormwater runoff into receiving waters or water bodies by temporary or permanent containment in a pond or depression; examples include systems which discharge by percolation to ground water, exfiltration, and/or evaporation processes and which generally have residence times of less than three days.

RETENTION BASIN

An impoundment designed to collect and retard stormwater runoff by temporarily storing the runoff and releasing it at a predetermined rate. Retention basins may also be designed to permanently retain additional stormwater runoff. Retention basins are designed to retain a permanent pool of water during dry weather.

RETURN PERIOD

The average interval, in years, within which a storm event of a given magnitude can be expected to occur one time. For example, the 25-year return period rainfall would be expected to occur on average once every 25 years.

RIPARIAN

Pertaining to anything connected with or immediately adjacent to the banks of a stream or other body of water.

RIPARIAN BUFFER

An area of land adjacent to a body of water and managed to maintain the integrity of stream channels and shorelines to (1) reduce the impact of upland sources of pollution by trapping, filtering and converting sediments, nutrients and other chemicals, and (2) supply food, cover and thermal protection to fish and other wildlife.

RUNOFF

See "Stormwater."

SEDIMENT

Fragmented material that originated from weathering rocks and decomposing organic material that is transported by, suspended in, and eventually deposited in the streambed.

SEDIMENTATION

Occurs when sediment particles that have been suspended within flowing water are deposited on the stream bottom or floodplain.

SHEET FLOW

A flow process associated with broad, shallow water movement on sloping ground surfaces that is not channelized or concentrated.

SCS

Soil Conservation Service or its successor.

SLAMM

Source Loading and Management Model. This model is based on small storm hydrology and pollutant runoff from urban land uses. Pollutant sources are identified and both structural and nonstructural stormwater practices can be accounted for in the model.

SPECIAL FLOOD HAZARD AREA

Those areas identified by the FEMA, Federal Insurance Administration (FIA) as floodway area (FW), flood fringe area (FF), and general floodplain area (FA); where determined by the Township, identified alluvial soils may be included as well.

STATE WATER QUALITY REQUIREMENTS

The regulatory requirements to protect, maintain, reclaim, and restore water quality under Pennsylvania Code Title 25 and the Clean Streams Law.

STORM EVENT

The storm of a specific duration, intensity, and frequency.

STORMWATER or RUNOFF

The flow of water overland and/or in water bodies that results from and occurs during and immediately following a rainfall event.

SWM

Stormwater Management.

STORMWATER MANAGEMENT ACT

See "Act 167."

STORMWATER MANAGEMENT BMPs

Is abbreviated as SWM BMPs or BMPs throughout this Chapter.

SWMM

Stormwater Management Model. EPA developed this model for analyzing stormwater quantity and quality associated with runoff from urban areas. Both single event and continuous simulation can be performed on catchments having storm sewers, or combined sewers and natural drainage, for prediction of flows, stages and pollutant concentrations.

STORMWATER MANAGEMENT PLAN

The Pine Creek, Deer Creek, Squaw Run and Girty's Run Stormwater Management Plan for managing stormwater runoff adopted by the County of Allegheny as required by the Act of October 4, 1978, P.L. 864 (Act 167), as amended, and known as the "Act 167 Stormwater Management Act".

STORMWATER MANAGEMENT PRACTICES

The designed and/or constructed features which infiltrate, treat, collect, convey, channel, store, inhibit, or divert the movement of stormwater; such practices include structural and non-structural practices.

STORMWATER MANAGEMENT SITE PLAN

The plan prepared for a developer by a qualified professional indicating how stormwater runoff shall be managed at the development site in accordance with this Chapter.

STRUCTURAL STORMWATER MANAGEMENT PRACTICES

Any measures that require the design and construction of a facility to help reduce or eliminate a non-point source of pollution and control stormwater.

STRUCTURE

Anything constructed or installed with a fixed location on the ground, or attached to something having a fixed location on the ground.

SUBAREA (SUBBASIN)

A portion of the watershed (basin) that has similar hydrological characteristics and drains to a common point.

SUBDIVISION

As defined in the Pennsylvania Municipalities Planning Code.

SUBDIVISION AND LAND DEVELOPMENT ORDINANCE

Chapter 174 of the Marshall Township Code of Ordinances, Subdivision and Land Development, as amended.

SUBGRADE

The top elevation of graded and compacted earth underlying roadway pavement.

SWALE

An artificial or natural waterway which may contain contiguous areas of standing or flowing water only following a rainfall event, or is planted with or has stabilized vegetation suitable for soil stabilization, stormwater treatment, and nutrient uptake, or is designed to take into account the soil erodibility, soil percolation, slope, slope length, and contributing drainage area so as to prevent erosion and reduce the pollutant concentration of any discharge.

TOTAL SITE AREA (SITE AREA)

Total area of the parcel(s) being developed.

TOWNSHIP

The Township of Marshall, Allegheny County, Pennsylvania.

TOWNSHIP ENGINEER

The professional engineer licensed as such in the Commonwealth of Pennsylvania and duly appointed as the engineer of the Township or his designee.

USDA

United States Department of Agriculture or its successor.

USDOT FHWA

United States Department of Transportation Federal Highway Administration or its successor.

WATER BODY

Any natural or artificial pond, lake, reservoir, or other area which ordinarily or intermittently contains water and which has a discernible shoreline and receives surface water flow.

WATER TABLE

The upper most level of saturation of pore space or fractures by subsurface water in an aquifer. Seasonal High Water Table refers to a water table that rises and falls with the seasons due either to natural or man-made causes.

WATERCOURSE

A permanent or intermittent stream or other body of water, whether natural or man-made, which gathers or carries surface water.

WATERS OF THE COMMONWEALTH

Any and all rivers, streams, creeks, rivulets, impoundments, ditches, watercourses, storm sewers, lakes, dammed water, wetlands, ponds, springs, and all other bodies or channels of conveyance of surface and underground water, or parts thereof, whether natural or artificial, within or on the boundaries of this Commonwealth.

WATERSHED

Region or land area drained by a river, watercourse, or other surface water of this Commonwealth to a downstream point.

WETLANDS

Land areas that are inundated or saturated by surface or groundwater with a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions (wetlands generally include swamps, marshes, bogs, and similar areas); or areas that are defined and delineated in accordance with the Federal Manual for Identifying and Delineating Jurisdictional Wetlands, dated January 10, 1989, and as may be amended from time to time; or as further defined and delineated by the United States Army Corps of Engineers, the United States Environmental Protection Agency, or the Pennsylvania Department of Environmental Protection.

WOODLAND CONDITION

A natural groundcover with more than one viable tree of a DBH (diameter at breast height) of six inches or greater per 1,500 square feet which existed within 10 years of application; a cover condition for which SCS curve numbers have been assigned or to which equivalent rational method runoff coefficients have been assigned.

ZONING OFFICER

The individual authorized by the Board of Supervisors to be the administrator of the day-to-day application of the provisions in this Chapter.

ZONING ORDINANCE

Chapter 208 of the Marshall Township Code of Ordinances, Zoning, as amended.

§ 165-104 General provisions.

1. Statutory authority.

A. Primary authority. The Township is empowered to regulate stormwater pursuant to the Pennsylvania Stormwater Management Act (commonly referred to as Act 167), and § 2704 of the Pennsylvania Second Class Township Code, 53 P.S. § 67704, as amended.

B. Secondary authority. The Township also is empowered to regulate land use activities that affect stormwater pursuant to the Municipalities Planning Code.

2. Applicability. The standards contained herein shall apply to all Regulated Activities within the Township. In addition, all Township, county and State erosion and sedimentation control approvals must be in place to proceed with any Regulated Activity.

A. Regulated activities (as defined in Section 165-103 of this Chapter) regulated by this Chapter include, but are not limited to, the following:

(1) Land development and redevelopment.

(2) Subdivision.

(3) Construction of new or additional impervious or semi-pervious surfaces (including driveways and parking lots).

(4) Construction of new buildings or additions to existing buildings.

(5) Diversion or piping of any natural or man-made stream channel.

(6) Installation of stormwater management facilities or appurtenances thereto.

(7) Any Earth Disturbances or any activities that involve the alteration or development of land or removal of tree and vegetation in a manner that may affect post construction stormwater runoff.

B. Redevelopments shall conform to the requirements contained in Section 165-106.1 when more than a 2,000 square feet area of an existing facility are reconstructed, following the demolition, or partial demolition of the existing facility. The area determination shall be made using the footprint of the area being reconstructed, including all impervious surfaces proposed in the reconstructed area and the area of the parking lot required to support the reconstructed facility. The area of the parking lot required to support the reconstructed facility shall be determined using the Zoning Ordinance (Chapter 208) requirements for parking.

3. Exemptions.

A. The following Regulated Activities are exempted from the requirement for on-site stormwater facilities and the preparation of a Stormwater Management Plan. All other stormwater management design elements, such as a storm sewer system, road culverts, erosion and sedimentation control, and runoff quality, are required. The Township Engineer may require implementation of on-site stormwater facilities and/or the preparation of a Stormwater Management Plan if he/she believes the facilities and/or Stormwater Management Plans are reasonably necessary to prevent flooding or protect surface water or groundwater of the Township.

(1) Regulated Activities smaller than 400 square feet are exempt from the requirements of this Chapter to implement SWM BMPs, unless the activity is found to be a significant contributor to pollution of the Waters of this Commonwealth.

(2) Small project exemption. Activities having a Disturbed Area of less than 5,000 square feet are exempt from the Peak Rate Control requirements of this Chapter. These projects shall comply with the Water Quality Volume standards contained in Section 165-106.3.A(1)(b) and the Extended Detention requirement contained in Section 165-106.3.A(1)(a). The "Small Project Standardized SWM Guidance" document provided in Appendix E was prepared to assist Applicants in meeting this requirement for individual lots only. The reduced site plan requirements contained in the "Small Project Standardized SWM Guidance" document shall apply. However, an E&S plan as per Section 165-104.10 shall be required. Conservation District approval of the E&S plan shall be required if a NPDES Construction Discharge Permit is required.

(3) Emergency exemption. Emergency maintenance work performed for the protection of public health, safety and welfare may be exempted from the requirements in this Chapter to obtain approval for a Stormwater Management Plan before commencement of the activity; however, a written description of the scope and extent of any emergency work performed shall be submitted to the Township within two calendar 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 may not resume until a written Stormwater Management Plan is submitted to and approved by the Township.

(4) Maintenance exemption. Any maintenance to an existing stormwater management system made in accordance with plans and specifications approved by the Township Engineer or the Township.

(5) Gardening. Use of land for gardening for home consumption.

(6) Agricultural activities. Agriculture when operated in accordance with a conservation plan, nutrient management plan or erosion and sedimentation control plan approved by the ACCD, including activities such as growing crops, rotating crops, tilling of soil and grazing animals. Installation of new or expansion of existing farmsteads, animal housing, waste storage and production areas having impervious surfaces that result in a net increase in impervious surface of less than 1,000 square feet are exempt from the requirement to submit a written Stormwater Management Plan.

(7) Forest management. Forest management operations, which are consistent with a sound forest management plan as filed with the Zoning Officer and which comply with: (1) the Township's Timber Harvesting and Forest Management regulations contained in Article 2400 of the Zoning Ordinance; and (2) the PADEP's management practices contained in its publication "Soil Erosion and Sedimentation Control Guidelines for Forestry." Such operations are required to have an erosion and sedimentation control plan as well as a Township timber harvesting permit.

(8) Roads. Earth Disturbance including road maintenance activities within the right-of-way of existing public roads.

4. Waivers.

A. If the Municipality determines that any requirement under this Chapter cannot be achieved for a particular regulated activity the Municipality may, after an evaluation of alternatives, approve measures other than those in this Chapter, subject to Subsection B. The proposed area of disturbance shall be less than one acre. The request for a modification or waiver shall originate with the Landowner, shall be in writing, and shall accompany the Stormwater Management Site Plan submitted to the Municipality. The request shall provide the facts on which the request is based, the provisions of the Ordinance involved, and the proposed modification. The Designated Plan Reviewer shall review the request to determine if it meets the requirements of the Ordinance, including Subsection B below. If acceptable to the Municipality, the Municipality may grant the waiver or modification.

B. Waivers or modifications of the requirements of this Chapter may be approved by the Municipality if enforcement will exact undue hardship because of unique physical circumstances or conditions peculiar to the land in question, provided that the modifications will not be contrary or detrimental to the public interest and will achieve the intended outcome, and that the purpose of the Ordinance is preserved. Hardship must be due to such unique physical circumstances or conditions and not to circumstances or conditions generally created by the provisions of the Stormwater Management Ordinance. Cost or financial burden shall not be considered a hardship. Modifications shall not substantially or permanently impair the appropriate use or development of adjacent property. A request for modifications shall be in writing and accompany the Stormwater Management Site Plan submission, as directed in Subsection A above.

C. No waiver or modification of any regulated stormwater activity involving earth disturbance greater than or equal to one acre may be granted by the Municipality.

D. The applicant for a waiver shall be required to notify all property owners location within 250 feet of the property subject to the waiver request. The notification shall include a description of the proposed development and the stormwater flows created, increased, decreased, relocated, impeded, or otherwise altered. Proof of notification (certified mail receipt for example) shall be included as part of the waiver request to the Municipality.

5. General requirements.

A. The management of stormwater on site, both during and upon completion of the disturbances associated with activities permitted under Section 165-104.2, shall be accomplished in accordance with the standards and criteria of this Chapter. The design of any temporary or permanent facilities and structures and the utilization of any natural drainage systems shall be in full compliance with this Chapter.

(1) The intent of the design standards contained in this Chapter is to encourage environmentally sound stormwater management practices that provide necessary drainage facilities while protecting the hydrologic characteristics and water quality of the site and watershed.

(2) Developments shall be required to incorporate stormwater management controls.

(3) Stormwater management design shall blend into the natural environment and be aesthetically integrated into the site design.

B. Applicants shall refer to the Pennsylvania Storm Water Best Management Practices Manual, as amended, Pennsylvania Handbook of Best Management Practices for Developing Areas (PACD, 1998), the 2000 Maryland Stormwater Design Manual (MDE, 2000) or other appropriate references for guidance in the design of stormwater management facilities most appropriate to individual site conditions. Objectives for design are to reduce the volume of stormwater generated, infiltrate runoff at its source to the maximum extent possible, achieve water quality improvement at the source or during conveyance, and provide for peak flow attenuation. Applicants shall examine design alternatives by viewing them in a series. In addition, Applicants are strongly encouraged to use structural and nonstructural stormwater management practices that reduce or eliminate the need for detention basins.

C. All SWM design work must be completed by a Qualified Design Professional. All designs proposing the use of a SWM retention or detention facility with outlet structure(s) shall be completed by an Engineer.

D. All development activity within a Special Flood Hazard Area designated by the Federal Emergency Management Agency (FEMA) shall comply with Article 1400 of the Zoning Ordinance (Chapter 208) and this subsection. All development shall be designed to maintain the flood carrying capacity of the floodway such that the base flood elevations are not increased, either upstream or downstream, unless an approval is received from PADEP. The natural conveyance characteristics of the site and the receiving floodplain shall be incorporated into the stormwater management practices proposed for the site.

E. The stormwater management system shall not create an adverse impact on stormwater quantity or quality in either upstream or downstream areas. Offsite areas which discharge to or across a site proposed for development shall be addressed in the stormwater management plan prepared for the development. No stormwater management plan shall be approved until it is demonstrated that the runoff from the project shall not significantly adversely impact downstream areas.

F. Wetlands shall not be used to meet the minimum design requirements for stormwater management or stormwater runoff quality treatment, except when used as part of a treatment train that incorporates a portion of the outer zone (filter strip) of the wetland's riparian buffer as a stormwater outfall.

G. All proposed stormwater management systems shall be designed to prevent the pollution of ground water resources by stormwater, promote safety, minimize health hazards, preserve natural features and provide infiltration and ground water recharge where appropriate. Neither submission of a plan under the provision herein nor compliance with the provisions of these Regulations shall relieve any person from responsibility for damage to any person or property otherwise imposed by law.

H. Where deemed necessary by the Township Engineer, or as addressed in an approved Act 167 stormwater management plan, the Applicant shall construct storm drains to handle on-site runoff; provide on-site/off-site drainage easements to the maximum extent permitted under the Municipalities Planning Code and Act 167, or any amendments thereto, and provide for the conveyance of off-site runoff to an acceptable outlet in the same watershed.

I. Where watercourses traverse a development site, drainage easements shall be provided conforming to the line of such watercourses. The terms of the easements shall prohibit excavation, the placing of fill or structures, except as needed for roadways, driveways and walkways, or any alterations that may adversely affect the flow of stormwater within any portions of the easement, and require the establishment and protection of riparian buffers.

J. For all Regulated Activities, stormwater management BMPs shall be designed, implemented, operated, and maintained to meet the purposes and requirements of this Chapter and to meet all requirements under Pennsylvania Code Title 25, the Clean Streams Law, and the Storm Water Management Act.

K. Any Regulated Activity that may affect the stormwater discharges toward or onto a State or County highway right-of-way or facility shall be designed, implemented, operated, and maintained in accordance with the regulations of PennDOT or Allegheny County, as the case may be.

L. At the time of application for a building permit for any approved lot created by a subdivision and/or improved as a land development project, issuance of the permit shall be conditioned upon adherence to the terms of this Chapter.

M. Stormwater discharges to critical areas with sensitive resources (e.g., special protection waters, cold water fisheries, recharge areas, water supply reservoirs, etc.) may be subject to additional performance criteria or may need to utilize or restrict certain stormwater management practices.

N. For all Regulated Earth Disturbance Activities, erosion and sediment control BMPs shall be designed, implemented, operated, and maintained during the Regulated Earth Disturbance Activities (e.g., during construction) to meet the purposes and requirements of this Chapter and to meet all requirements under the Pennsylvania Code Title 25 and the Clean Streams Law, including permits, where applicable. Various BMPs and their design standards are listed in the Erosion and Sediment Pollution Control Program Manual (E&S Manual), Commonwealth of Pennsylvania, Department of Environmental Protection, No. 363-2134-008, as amended and updated.

O. No Regulated Earth Disturbance Activities within the Township shall commence until the requirements of this Chapter are met.

P. Post-construction water quality protection shall be addressed as required by the Stormwater Management requirements contained in this Chapter.

Q. Operations and maintenance of permanent stormwater BMPs shall be addressed as required by Section 165-107.

R. All best management practices (BMPs) used to meet the requirements of this Chapter shall conform to the State Water Quality Requirements, and any more stringent requirements as required by the Township.

S. Techniques described in Appendix B (Non-Structural Stormwater Management Practices) of this Chapter are encouraged, because they reduce the costs of complying with the requirements of this Chapter and the State Water Quality Requirements.

T. In selecting the appropriate BMPs or combinations thereof, the Applicant shall consider the following:

(1) Total contributing area.

(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.

(6) Erodibility of soils.

(7) Land availability and configuration of the topography.

(8) Peak discharge and required volume control.

(9) Stream bank erosion.

(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.

U. Transference of runoff from one PADEP designated Act 167 watershed to another shall be prohibited unless approved by the Township.

6. Repealer. Any ordinance or ordinance provision of the Township inconsistent with any of the provisions of this Chapter is hereby repealed to the extent of the inconsistency only; provided, however, that this repeal shall in no manner be construed as a waiver, release or relinquishment of the right to initiate, pursue or prosecute, as the case may be, any proceeding at law or in equity pertaining to any act done which would have constituted a violation of such prior ordinance or ordinance provision. All of said ordinance or ordinance provisions shall remain in full force and effect and are not repealed hereby as they pertain to such acts and to the processing of such plans filed prior to the effective date of this Chapter, which are protected from the effect of intervening ordinances by Section 508(4) of the Pennsylvania Municipalities Planning Code.

7. Severability. Should any section or provision of this Chapter be declared invalid by a court of competent jurisdiction, such determination of invalidity shall not affect the validity of the remaining provisions of this Chapter.

8. Compatibility with other ordinance requirements. Permits and approvals issued pursuant to this Chapter shall not relieve the Applicant of the responsibility to comply with or to secure other required permits or approvals for activities regulated by any other applicable code, rule, act, statute or ordinance. This Chapter shall not preclude the inclusion in such other permit of more stringent requirements concerning regulation of stormwater and erosion. Where a conflict exists between a provision within this Chapter and that of the PADEP Phase II NPDES regulations, as amended, or any other ordinance of the Township, the more stringent requirements shall govern.

9. Permit requirements by other government entities.

A. All regulated earth disturbance activities subject to permit requirements by PADEP under regulations at 25 Pa. Code Chapter 102.

B. Work within natural drainage ways subject to permit by PADEP under 25 Pa. Code Chapter 105.

C. Any stormwater management facility that would be located in or adjacent to surface waters of the Commonwealth, including wetlands, subject to permit by PADEP under 25 Pa. Code Chapter 105.

D. Any stormwater management facility that would be located on a State highway right-of-way, or require access from a State highway, shall be subject to approval by PennDOT.

E. Culverts, bridges, storm sewers or any other facilities which must pass or convey flows from the tributary area and any facility which may constitute a dam subject to permit by PADEP under 25 Pa. Code Chapter 105.

10. Erosion and sediment control during regulated earth disturbance activities.

A. No Regulated Earth Disturbance Activities within the Township shall commence until the Township receives a copy of any required approvals from the ACCD or PADEP for an Erosion and Sediment Control Plan.

B. PADEP has regulations that require an Erosion and Sediment Control Plan for any earth disturbance activity of 5,000 square feet or more, under 25 Pa. Code § 102.4(b).

C. In addition, under 25 Pa. Code Chapter 92, a PADEP "NPDES Construction Activities" permit is required for certain Regulated Earth Disturbance Activities.

D. Evidence of any necessary permit(s) for Regulated Earth Disturbance Activities from PADEP or ACCD must be provided to the Township.

E. A copy of the Erosion and Sediment Control plan and any required permits, as required by PADEP regulations, shall be available at the project site at all times.

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

(1) Areas proposed for infiltration BMPs shall be protected from sedimentation and compaction during the construction phase to maintain design infiltration capacity.

(2) Infiltration BMPs shall not be constructed nor receive runoff until the entire contributory drainage area to the infiltration BMP has achieved final stabilization.

11. SWM plans onsite during period of construction.

A. An approved copy of the SWM Site Plan and Report shall be on site throughout the entire period of construction.

12. Prohibited discharges and connections.

A. No person in the Township shall allow, or cause to allow, stormwater discharges into the Township's separate storm sewer system and or Waters of this Commonwealth which are not composed entirely of stormwater, except (1) as provided in Section 165-104.11.B below, and (2) discharges allowed under a State or Federal permit.

B. The following discharges are authorized unless they are determined to be significant contributors to pollution to the Waters of this Commonwealth:

•	Discharges from firefighting activities;
•	Potable water sources including dechlorinated water line and fire hydrant flushings;
•	Irrigation drainage;
•	Routine external building washdown (which does not use detergents or other compounds);
•	Air conditioning condensate;
•	Water from individual residential car washing;
•	Spring water from crawl space pumps;
•	Uncontaminated water from foundation or from footing drains;
•	Flows from riparian habitats and wetlands;
•	Lawn watering;
•	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 are not used;
•	Dechlorinated swimming pool discharges;
•	Uncontaminated groundwater.

C. In the event that the Township determines that any of the discharges identified in Section 165-104.11.B significantly contribute to pollution of waters of the Commonwealth, or is so notified by PADEP, the Township or PADEP will notify the responsible person to cease the discharge.

D. Nothing in this Section shall affect a discharger's responsibilities under State law.

E. Existing roof drain, underdrain and sump pump discharges should be directed to lawn area or other pervious areas where feasible and consistent with good engineering practice. If required by the Township, the discharge shall be directed to a stone sump or infiltration BMP. If approved by the Township, the discharge may also be directly connected to the storm sewer system.

13. Enforcement and penalties.

A. Right-of-entry. The Zoning Officer and any authorized representative of the Township shall have the right to enter any property within the Township at reasonable times to inspect and/or investigate any condition associated with this Chapter.

B. Inspection. SWM BMPs should be inspected by the land owner/developer (including Township for dedicated facilities) according to the following list of frequencies:

(1) Annually for the first five years.

(2) Once every three years thereafter.

(3) During or immediately after the cessation of a 10-year or greater storm event.

C. Enforcement.

(1) It shall be unlawful for a person to undertake any Regulated Activity except as provided in an approved SWM Plan.

(2) It shall be unlawful to alter or remove any control structure required by the SWM Plan.

(3) Inspections regarding compliance with the SWM Plan are a responsibility of the Township.

D. Suspension and revocation.

(1) Any approval for a Regulated Activity issued may be suspended or revoked, in whole or in part, by the Township for:

(a) Non-compliance with or failure to implement any provision of the approval.

(b) A violation of any provision of this Chapter or any other applicable law, Ordinance, rule or regulation relating to the Regulated Activity.

(c) The creation of any condition or the commission of any act during the Regulated Activity which constitutes or creates a hazard or nuisance, pollution, or which endangers the life or property of others.

(2) A suspended approval may be reinstated by the Township when:

(a) The Township has inspected and approved the corrections to the violations that caused the suspension.

(b) The Township is satisfied that the violation has been corrected or will be corrected according to an enforceable schedule agreed to by the Township.

(3) An approval that has been revoked by the Township may be reinstated, or the Township may require the Applicant to apply for a new approval under the provisions of this Chapter.

(4) Prior to revocation or suspension of a permit, if there is no immediate danger to life, public health, or property, the Township may notify the land owner/developer to discuss the non-compliance.

E. Penalties. Any person, firm or corporation who violates any provision of this Chapter, or fails to comply therewith, or with any of the requirements thereof, upon conviction thereof in an action brought before a magisterial district judge in the manner provided for the enforcement of summary offenses under the Pennsylvania Rules of Criminal Procedures, shall be sentenced to pay a fine of not less than $300 nor more than $1,000 plus costs, including reasonable attorney fees incurred by the Township, and in default of said fine and costs, to a term of imprisonment to the extent permitted by law for the punishment of summary offenses. A separate offense shall arise for each day or portion thereof in which a violation of this Chapter is found to exist or for each section of this Chapter is found to have been violated. The Township may also commence appropriate actions in equity or otherwise to prevent, restrain, correct, enjoin, or abate violations of this Chapter. All fines and penalties collected for violation of this Chapter shall be paid to the Township Treasurer. The initial determination of violation and the service of any required notice of violation are hereby delegated to the Township Manager, the Township Code Official/Building Inspector, the Code Enforcement Officer, the Zoning Officer and their designees and to any other officer or agent that the Township Secretary or the Board of Supervisors shall deem appropriate.

14. Appeals. Any person aggrieved by any decision of the Township, relevant to the provisions of this Chapter, may appeal to the Allegheny County Court of Common Pleas within 30 days of the Township's decision.

15. Erroneous permit. Any permit or authorization issued or approved based on false, misleading or erroneous information provided by an applicant is void without the necessity of any proceedings for revocation. Any work undertaken or use established pursuant to such permit or other authorization is unlawful. No action may be taken by a board, agency or employee of the Municipality purporting to validate such a violation.

§ 165-105 Stormwater management plan.

For all Regulated Activities not eligible for exemptions pursuant to Section 165-104.3 of this Chapter, the Applicant shall submit to the Township a Stormwater Management Plan and report prepared by an Engineer, which shall contain, but not be limited to, the following. Final copies of all plans, specifications and reports shall also be submitted to the Township in Adobe PDF electronic format and be available on site throughout the period of construction.

A. A suitable map of the watershed for any and all named streams within which the project is proposed (a United States Geological Survey quadrangle map is usually sufficient) with existing and proposed development areas presented on the map.

B. Suitable maps and drawings showing all existing natural and constructed drainage facilities affecting the subject property.

C. Hydrologic (watershed) and water feature boundaries, including all areas flowing to the proposed project, existing streams (including first order and intermittent streams), springs, lakes, ponds, or other bodies of water within the project area.

D. Sufficient topographical information with elevations to verify the location of all ridges, streams, etc. (two-foot contour intervals within the project's boundaries and for proposed offsite improvements; for slopes greater than 15%, five-foot contours are acceptable).

E. Notes pertaining to and locations of existing standing water, areas of heavy seepage, springs, wetlands, streams, and hydrologically sensitive areas. The Chapter 93 Water Quality Standards use designation must also be provided on the plan.

F. General type of soils with Hydrologic Soil Group noted, estimated permeabilities in inches per hour, and location and results of all soil tests and borings (if needed).

G. 100-year flood elevations for any Special Flood Hazard Areas on or within 100 feet of the property. For redevelopment sites, also show the 10- and 25-year flood elevations for any Special Flood Hazard Areas on or within 100 feet of the property. The source of these elevations shall also be shown on the plans.

H. The following signature block for the Municipality:

On this date __________, the Marshall Township has reviewed and hereby certifies that the SWM Site Plan meets all design standards and criteria of the Municipal SWM Ordinance No. 165, except where waivers have been granted as noted on the Plan. The review is based on a survey and plan prepared by others and assumes that all information is correct and valid as submitted."

I. Description of current and proposed ground cover and land use. The total area and percent impervious cover shall be noted.

J. A wetland delineation report for the project site with a location map identifying wetland areas if any were found.

K. A plan of the proposed stormwater drainage system attributable to the activity proposed, including runoff calculations, stormwater management practices to be applied both during and after development, and the expected project time schedule.

L. The design computations for all proposed stormwater drainage systems, including storm-drain pipes, inlets, runoff control measures and culverts, drainage channels, and other features, facilities, and stormwater management practices.

M. A grading plan, including all areas of disturbance of the subject activity. The total area of disturbance shall be noted in square feet and acres. Topographic contours showing the existing and proposed final contours at an interval of two feet; in areas having slope of greater than 15%, a five foot contour interval may be used.

N. A plan of the erosion and sedimentation procedures to be utilized as required by applicable Township, Allegheny County and State laws, statutes, ordinances and regulations.

O. The effect of the project (in terms of runoff volumes and peak flows) on adjacent properties and on any other stormwater collection system that may receive runoff from the project site and specifics of how erosion and flooding impacts to adjacent properties will be avoided or otherwise mitigated.

P. An operation and maintenance plan consistent with the requirements of Section 165-107. Such a plan should clearly explain how the proposed facilities operate and the functions they serve.

Q. The name of the development, the name and address of the property owner and Applicant, and the name and address of the individual or firm preparing the plan.

R. A north arrow, submission date, graphic scale and revision dates as applicable shall be included on each page of all plans submitted.

S. Complete delineation of the flow paths used for calculating the time of concentration for the pre-developed and post-developed conditions.

T. Construction details sufficient to completely express the intended stormwater design components consistent with this Chapter.

U. A listing of all permits required for the site providing the status of the permit application(s) and approval(s).

V. All existing and proposed easements and rights-of-way for drainage and/or stormwater control facilities shall be shown and the proposed owner identified. Show any areas subject to special deed restrictions relative to or affecting stormwater management on the development site.

§ 165-106 Permanent stormwater management design standards.

1. Design goals, principles and standards.

A. Design goals. Applicants shall adhere to a holistic design process incorporating the goals listed below. The objective is to achieve post-development hydrologic conditions that are consistent with the predevelopment ground cover assumption for new development (refer to Section 165-106.2.A(2)) and improve the runoff conditions for redevelopment (refer to Section 165-106.2.E). The design goals are:

(1) Minimize the volume of runoff that must be collected, conveyed, treated and released by stormwater management facilities;

(2) Maintain the natural infiltration process and rate, and infiltrate runoff at its source when appropriate;

(3) Remove and/or treat pollutants at the source or during conveyance through the application of Best Management Practices;

(4) Provide for peak flow attenuation, as needed; and

(5) Attenuate runoff to protect the instream channel of the receiving stream.

B. General principles. The following general principles apply to all Regulated Activities pursuant to Section 165-104.2.

(1) Incorporate Conservation Design practices to minimize the amount of stormwater generated on a site, encourage the disconnection of impervious land cover, and maximize the use of pervious areas for stormwater treatment and on-site rainfall infiltration.

(2) Infiltration of surface water runoff at its source is to be a mechanism for stormwater management based on hydrologic soil group (or infiltration testing). Infiltration practices include, but are not limited to, those referenced in Section 165-106.3.B(1) and as outlined in the publications listed in Section 165-106.3. Infiltration practices shall adhere to the following criteria:

(a) In choosing methods of infiltration, preference shall be given to a combination of surface and subsurface infiltration methods.

(b) Applicants shall first consider minimum disturbance/minimum maintenance techniques combined with site grading that distributes runoff to reduce concentration. Next, Applicants shall consider depression areas combined with subsurface infiltration practices followed by other subsurface measures, including, but not limited to, porous paving and perforated pipe storage.

(c) The use of multiple infiltration features and facilities that provide for the following is encouraged:

1) Discourage concentration of flows,

2) Encourage disconnection of flows,

3) Infiltrate as close to the source of runoff as possible, and

4) Reduce visual impact.

(3) Where high water tables, subsurface contamination, slope stability concerns, or other site constraints preclude achieving the required infiltration volume, additional Conservation Design practices and alternative stormwater management practices should be implemented to reduce to the maximum extent practicable the total volume of stormwater released to streams. Applicant shall follow the stormwater runoff hierarchy of Section 165-106.3.A(1)(a).

(4) Infiltration areas should be designed to maintain any broad and even infiltration pattern which existed prior to development. Such facilities should use the natural topography and vegetation in order to blend in with the site. Infiltration designs, which do not provide this may be used if the Applicant demonstrates to the Township's satisfaction that alternative approaches would be more effective, more harmonious with their existing environment and as easily maintained.

(5) Above ground stormwater infiltration facilities should be as shallow as possible while still achieving the requirements of this Chapter.

(6) Water quality improvement shall be the goal to be achieved in conjunction with or as part of infiltration practices. Water quality improvements shall also be provided for drainage areas not otherwise addressed by infiltration practices either at the source of runoff and/or during conveyance away from the source of runoff.

(7) To reduce the need for large retention and/or detention basins designed to satisfy the peak flow attenuation and extended detention requirements, other innovative stormwater management practices located close to the source of runoff generation shall be considered, including a combination of practices (e.g., rooftop storage, open vegetated channels, bioretention, pervious pavement systems and infiltration trenches).

(8) When designing stormwater management facilities to satisfy the peak flow attenuation and extended detention requirements (refer to Section 165-106.1.D(2)), the effect of structural and non-structural stormwater management practices implemented as part of the overall site design may be taken into consideration when calculating total storage volume and release rates.

(9) Site hydrology and natural infiltration patterns shall guide site design, construction and vegetation decisions. All channels, drainage ways, swales, natural streams and other surface water concentrations shall be considered and where possible incorporated into design decisions.

C. Minimum performance criteria.

(1) The following minimum performance standards shall apply to all Regulated Activities, whether they are new development or redevelopment, pursuant to Section 165-104.2.

(a) Water quality treatment (Volume Control) of stormwater runoff shall be provided for all discharges prior to release to a receiving water body. If a stormwater management practice does not provide water quality treatment, then water quality best management practices shall be utilized prior to the runoff entering the stormwater management practice.

(b) Water quality management shall be provided through the use of structural and/or non-structural stormwater management practices. Water quality stormwater management practices shall be designed to reduce or eliminate solids, sediment, nutrients, and other potential pollutants from the site. It is presumed that a stormwater management practice complies with this requirement if it is:

1) Designed according to the specific performance criteria outlined in Section 165-104.5.B.

2) Constructed in accordance with all permits and approved plans and specifications; and

3) Maintained per an approved operation and maintenance plan or agreement or, in lieu of that, in accordance with customary practices.

(c) Stormwater discharges from land uses or activities with higher potential for pollutant loadings (hotspots) may require the use of specific structural stormwater management practices and pollution prevention practices. In addition, stormwater from a hotspot land use shall be provided with proper pretreatment prior to infiltration. For the purpose of this Chapter, the sites/facilities listed in Section 165-106.3.C(1)(d) below, are considered hotspots.

(d) Certain industrial sites may be required to prepare and implement a stormwater pollution prevention plan and file notice of intent as required under the provision of the EPA Industrial Stormwater NPDES Permit Requirements. Other industrial sites storing significant quantities of chemicals/wastes should also prepare a prevention plan. Sites that are required by EPA to prepare a plan include, but are not limited to:

1) Vehicle salvage yards and recycling facilities;

2) Vehicle and equipment cleaning facilities;

3) Fleet storage areas for buses, trucks etc.;

4) Marinas (service and maintenance);

5) Facilities that generate or store hazardous materials.

(e) Conveyance structures/channels shall be designed and adequately sized so as to protect the properties receiving runoff from impacts of flooding and erosion. Where necessary, and to the maximum extent permitted under the Municipalities Planning Code and Act 167, or any amendments thereto drainage easement from adjoining properties shall be obtained to ensure the drainage way and the property and shall also establish the operation and maintenance requirements for the drainage way.

(f) All stormwater management practices shall have an Operation and Maintenance Plan pursuant to Section 165-107.3 of this Chapter, and if to be privately owned, an enforceable Operation and Maintenance Agreement per Section 165-107.4 of this Chapter to ensure the system functions as designed and to provide remedies for system failure.

(g) Stormwater runoff generated from development and discharged directly into Wetlands or waters of the United States and their adjacent Wetlands shall be treated by an approved stormwater management practice prior to release into a natural wetlands and shall not be used to meet the minimum design requirements for stormwater management or stormwater runoff quality treatment, except when used as part of a treatment train that incorporates a portion of the outer zone (filter strip) of the wetland's riparian buffer as a stormwater outfall. In such instances, the discharge velocity from the terminal end of a pipe or associated energy dissipation practice shall not exceed two feet per second for the two-year frequency storm event. Where such a management strategy is used, all feasible methods shall be used to convert concentrated flow to uniform, shallow sheet flow before entering the outer zone of the Wetlands' riparian buffer. In addition, it shall be demonstrated that such an approach will not cause erosion.

D. The following minimum performance standards shall apply to all new development Regulated Activities, pursuant to Section 165-104.2.A.

(1) Water quality improvement shall be the goal in conjunction with or as part of infiltration practices (if used). Water quality improvements shall also be provided for drainage areas not otherwise addressed by infiltration practices either at the source of runoff and/or during conveyance away from the source of runoff. Stormwater quality management practices shall be designed to capture and treat stormwater runoff generated by the one-inch rainfall event. Refer to Section 165-106.A(1)(b) for Water Quality Volume design standards and assumptions. Stormwater quality management practice selection, design and implementation shall be based upon appropriate reference materials, as provided in Section 165-104.5.B.

(2) The post development peak discharge rate shall not exceed the predevelopment peak discharge rate multiplied by the "subbasin release rate percentage" (where determined in Act 167 watersheds) for the one-year, two-year, five-year 10-year, 25-year, 50-year and 100-year 24-hour storm events pursuant to the predevelopment cover assumption described in Section 165-106.2.A(2). For areas outside the Pine Creek Watershed, the release rate percentage shall be 80%. Refer to Appendix A for release rate percentages information.

(3) Facilities capable of attenuating rainfall runoff shall be provided and be designed to attenuate the runoff volume from the two-year 24-hour storm event for at least 24 hours.

(4) Stormwater shall be infiltrated and/or discharged within the same drainage area of the stream receiving the runoff from the development site prior to development.

(5) Structural and non-structural stormwater management practices that make best possible use of infiltration on-site shall be considered in all site designs, when appropriate.

E. The following minimum performance standards shall apply to all redevelopment Regulated Activities, pursuant to Section 165-104.2.B.

(1) One of the following minimum performance standards shall be accomplished. Selection of the performance standard shall be whichever is most appropriate for the given site conditions:

(a) Reduce the total impervious cover on the site (e.g., by using pervious pavement, replacement of pavement with pervious planting areas or green roof systems) by at least 25%, based on a comparison of existing impervious cover to proposed impervious cover; or

(b) Provide facilities designed to attenuate the runoff volume from the two-year 24-hour post development storm event for at least 24 hours; and

(c) Provide facilities to ensure that the post development peak discharge rate shall not exceed the predevelopment peak discharge rate multiplied by the "subbasin release rate percentage" (where determined in Act 167 watersheds) for the two-year and 10-year 24-hour storm events. A predevelopment cover CN of 71 shall be assumed. For areas outside the Pine Creek Watershed, the release rate percentage shall be 80%.

(2) In addition to the minimum performance standards for redevelopment areas in Section 165-106.1.E above, water quality (Volume Control) improvements shall be provided for drainage areas not otherwise previously addressed during prior land development activities on the property.

2. Stormwater runoff (rate control) calculation criteria.

A. In addition to the infiltration and water quality (Volume Control) requirements of this Chapter, peak flow from those activities resulting in increases in impervious surface and/or regrading and compaction shall be attenuated consistent with the following stormwater calculation methods:

(1) The following design storms shall be used for analysis of the pre and post development conditions. These values are applicable to the Soil-Cover-Complex Method:

Return Period (years)	24-Hour Storm (inches)
1	2.00
2	2.35
5	2.88
10	3.30
25	3.91
50	4.40
100	4.92

The precipitation values for each frequency storm listed above were abstracted from the precipitation frequency estimates developed by the National Oceanic and Atmospheric Administration as set forth in NOAA Atlas 14, Volume 2 (NOAA June 2004). The NOAA data are available from the Hydrometeorological Design Studies Center of the National Weather Service. The NOAA Atlas 14, Volume 2 report can be accessed from the NOAA website at http://hdsc.nws.noaa.gov/hdsc/pfds/.

(2) The following assumptions shall be used for runoff calculations:

(a) For new development sites, the ground cover used as the predevelopment assumption for runoff calculations shall be as follows;

1) Wooded sites shall use a ground cover of woodland in good condition. Portions of a site having more than one viable tree of a DBH (Diameter at breast height (DBH) is the diameter of the tree stem 4½ feet above the ground) of six inches or greater per 1,500 square feet shall be considered wooded where such trees existed within 10 years of application. If there is evidence of logging within the 10-year period logged area shall be consider as woodland in good condition.

2) Agricultural sites shall use a ground cover of pasture in good condition.

3) All other portions of a site shall use a ground cover of meadow in good condition.

4) All watershed area(s) contributing to the point of interest including off-site area shall be considered.

5) For redevelopment sites, see Section 165-106.1.E.

(b) The runoff curve numbers listed in the table below shall be used in developing the runoff calculations for the ground covers noted in Section 165-106.2.A(2)(a). These values are referenced from the Urban Hydrology for Small Watersheds Technical Release No. 55 (USDA, 1986). Coefficients for equivalent ground cover conditions shall be used if a runoff method other than the Soil Cover Complex Method is used.

Ground Cover	Hydrologic Soil Group Curve Numbers
	A	B	C	D
Woodland	30	55	70	77
Meadow	30	58	71	78
Grass	39	61	74	80

(c) Impervious cover shall have a curve number of 98.

(d) Gravel pavement shall have a curve number of 89.

(e) Average antecedent moisture conditions, or AMC II, shall be used (for the Soil Cover Complex Method only for example, TR-55, TR-20).

(f) A type II distribution storm (for the Soil Cover Complex Method only for example, TR-55, TR-20).

(g) For time of concentration calculations, sheet flow lengths shall not exceed 100 feet and shallow concentrated flow lengths shall not exceed 1,000 feet.

(h) The kinematic "n" value in the sheet flow equation should be applied as per the following table. (Values taken from TR-55.)

Impervious Surfaces	0.011
Agricultural Lands	0.17
Grass, Lawn, or Open Space	0.24
Wooded Areas	0.40

B. In all plans and designs for stormwater management systems and facilities submitted to the Township Engineer for approval, stormwater peak discharge and runoff shall be determined through the use of the NRCS Soil Cover Complex Method as set forth in Urban Hydrology for Small Watersheds, Technical Release No. 55 (USDA, 1986), with specific attention given to antecedent moisture conditions, flood routing, time of concentration, and peak discharge specifications included therein and in Hydrology National Engineering Handbook, Section 4, (USDA, 1985) both by the U.S. Department of Agriculture, Natural Resources Conservation Service. Note that when TR-55 is used for natural system-based approaches and practices encouraged herein, calculations must be performed on a detailed small sub-area basis. Use of Technical Release No. 20 and other methods listed in Table 1 are also acceptable. The design professional's selection of a specific method shall be based on the suitability of the method for the given project site conditions with due consideration to the limitations of the method chosen. Table 1 herein summarizes the computational methods available.

Table 1 Acceptable Computation Methodologies for Stormwater Management Plans
Method	Source	Applicability
TR-20 or commercial Package Based on TR-20	USDA — NRCS	When use of full model is desirable or necessary
TR-55 or Commercial Package Based on TR-55	USDA — NRCS	Applicable for plans within the model's limitations
HEC — HMS	U.S. Army Corps of Engineers	When full model is desirable or necessary
PSRM	Penn State University	When full model is desirable or necessary
VT/PSUHM	Virginia Polytechnic Institute & Penn State University	When full model is desirable or necessary
Modified Rational Method or Commercial package based on this Method	Emil Kuiching (1889)	For sites less than 20 acres
SWMM or commercial package based on SWMM	U.S. EPA	Most applicable in urban areas
Small Storm Hydrology Method (as included in SLAMM)	PV & Associates, or the website www.winslamm.com	Calculation of runoff volume from urban and suburban areas

C. A Modified Rational Method analysis may be used for drainage areas smaller than two acres when permitted by the Township Engineer. The term "Modified Rational Method" used herein refers to a procedure for manipulation of the basic rational method techniques to reflect the fact that storms with a duration greater than the normal time of concentration for a basin will result in a larger volume of runoff even though the peak discharge is reduced. The methodology and model chosen for use shall be well documented as being appropriate for use in this region, and all relevant assumptions, methodologies, calculations and data used shall be provided to the Township Engineer for review. Information on the Modified Rational Method is presented in the Recommended Hydrologic Procedures for Computing Urban Runoff from Small Watersheds in Pennsylvania (PADEP, 1982).

D. Rainfall intensities used for the Modified Rational Method shall be based on the precipitation frequency estimates developed by the National Oceanic and Atmospheric Administration as set forth in NOAA Atlas 14.

E. The Rational Method (that is, Q = CIA) shall be used for calculations of the peak rate of runoff for the design of storm sewers and drainage swales but not for the design of stormwater management facilities where a full hydrograph is needed. The equation representing the Rational Method is comprised of the following (in English units):

Q = Peak flow rate, cubic feet per second (CFS)

C = Runoff coefficient, dependent on land use/cover

I = Design rainfall intensity, inches per hour

A = Drainage area, acres

F. Runoff characteristics of off-site areas that drain through a proposed development shall be considered and be based on the existing conditions in the off-site area.

3. Standards for stormwater management practices. The Pennsylvania Stormwater Best Management Practices Manual shall serve as a guide for the design of stormwater management practices. Additional design guidance may also be obtained from other related sources, including the 2000 Maryland Stormwater Design Manual, Volumes I and II (MDE, 2000), Design of Stormwater Filtering Systems (CWP, 1996), and the American Society of Civil Engineers Manual and Report on Engineering Practice, No. 87, Urban Runoff Quality Management (ASCE, 1998) for the design of stormwater runoff quality control features for site development. A list of references is provided with this Chapter. Pursuant to the design options recommended in the above documents, the following standards shall be adhered to:

A. Extended detention, water quality volume, infiltration & nonstructural BMP credits criteria.

(1) The following sizing criteria shall be followed at all sites required to meet the standards of this Chapter.

(a) Extended detention.

1) Detain the two-year, 24-hour design storm using the SCS Type II distribution. Provisions shall be made so that the two-year storm takes a minimum of 24 hours to drain from the facility from a point where the maximum volume of water from the two-year storm is captured. (i.e., the maximum water surface elevation is achieved in the facility). 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 potential.

2) Detention ponds shall detain the two-year storm event and allow it to naturally infiltrate and recharge the groundwater table. All subsequent orifices for the two, 10, 25, and 100-year storm events shall be placed above the maximum water surface elevation of the two-year storm.

3) Flow from off-site areas must be considered as pass-through flow if it is conveyed through the BMP and should be modeled as "present condition" for the one-year storm event.

4) The length of overland flow used in time of concentration (tc) calculations is limited to no more than 100 feet for post development conditions.

5) The models TR-55 and TR-20 (or approved equivalent) can be used for determining peak discharge rates.

6) The all Detention Facilities with Volume and Rate Control functions must fully drain in a period between 24 and 72 hours after the design storm event ends.

(b) Volume control (water quality volume).

1) The green infrastructure and low impact development practices provided in the BMP Manual shall be utilized for all regulated activities wherever possible. Water volume controls shall be implemented using the Design Storm Method in Subsection A or the Simplified Method in Subsection B below. Water volume controls shall be implemented using the Design Storm Method in Subsection A or the Simplified Method in Subsection B below, or alternative design criteria as allowed by PA Code Title 25, Chapter 102.

a) The Design Storm Method (CG-1 in the BMP Manual³) is applicable as a method to any size of regulated activity. This method requires detailed modeling based on site conditions. The following shall be incorporated into the CG-1 method:

i. Do not increase the post-development total runoff volume for all storms equal to or less than the two-year 24-hour duration precipitation.

ii. At least the first one inch of runoff from the net increase in impervious surfaces shall be permanently removed from the runoff flow, i.e., it shall not be released into the surface waters of this Commonwealth. Removal options include reuse, evaporation, transpiration, and infiltration. If the developer provides justification that the listed removal options are not feasible, and the Designated Plan Reviewer agrees, runoff shall be detained in a facility designed for a 24- to 72-hour dewatering time in an area with a dedicated stormwater system (not contributory to a combined sewer system) and shall be detained in a facility designed for a 72-hour dewatering time in an area contributory to a combined sewer system before discharge to local stormwater systems or the environment.

iii. For modeling purposes:

a. Existing (predevelopment) non-forested pervious areas must be considered meadow in good condition.

b. 20% of existing impervious area, when present, shall be considered meadow in good condition in the model for existing conditions.

b) The Simplified Method (CG-2 in the BMP Manual) provided below is independent of site conditions and should be used if the Design Storm Method is not followed. This method is not applicable to regulated activities greater than one acre or for projects that require design of stormwater storage facilities. For new impervious surfaces:

i. Stormwater facilities shall capture at least the first two inches of runoff from the net increase in impervious surfaces.

ii. At least the first one inch of runoff from the net increase in impervious surfaces shall be permanently removed from the runoff flow, i.e., it shall not be released into the surface waters of this Commonwealth. Removal options include reuse, evaporation, transpiration, and infiltration. If the developer provides justification that the listed removal options are not feasible, and the Designated Plan Reviewer agrees, runoff shall be detained in a facility designed for a 24-hour dewatering time in an area with a dedicated stormwater system (not contributory to a combined sewer system) and shall be detained in a facility designed for a 72-hour dewatering time in an area contributory to a combined sewer system before discharge to local stormwater systems or the environment.

iii. Wherever possible, infiltration facilities should be designed to accommodate infiltration of the entire permanently removed runoff; however, in all cases at least the first 0.5 inch of the permanently removed runoff should be infiltrated.

iv. This method is exempt from the requirements of Section 165-106.2, Rate Controls.

(c) Infiltration volume. Where possible, all of the Water Quality Volume should be treated using infiltration BMPs. Infiltration testing per PA DEP recommendations is required.

1) Infiltration should not be considered for sites or areas of sites that have activities that may allow pollution to be infiltrated. For example the use of infiltration for the runoff of a service stations paved lot would not be appropriate, although roof water from the service station may be infiltrated.

2) Infiltration should only be used when in the opinion of a professional engineer it will not contribute to slope instability or cause seepage problems into basements or developed down-gradient areas.

3) All infiltration facilities shall be set back at least 15 feet from all structures with sub-grade elements (e.g., basements, foundation walls).

(d) Credits for use of nonstructural BMPs. The developer may obtain credits for the use of nonstructural BMPs using the procedures outlined below. Examples of nonstructural credit calculations are provided in Appendix D.

1) Volume Reduction Method #1: Natural Area Conservation.

a) A water quality volume reduction can be taken when undisturbed natural areas are conserved on a site, thereby retaining their pre-development hydrologic and water quality characteristics. Under this method, a designer would be able to subtract the conservation areas from the total site area when computing the water quality protection volume. An added benefit is that the post-development peak discharges will be smaller, and hence, water quantity control volumes will be reduced due to lower post-development curve numbers or rational formula "C" values.

b) Rule: Subtract conservation areas from total site area when computing water quality protection volume requirements.

c) Criteria:

i. Conservation area cannot be disturbed during project construction and must be protected from sediment deposition. The conservation area shall be protected with a safety fence until construction has been completed. After construction the area shall be posted with signage indicating that it is a conservation area.

ii. Shall be protected by limits of disturbance clearly shown on all construction drawings.

iii. Shall be located within an acceptable conservation easement instrument that ensures perpetual protection of the proposed area. The easement must clearly specify how the natural area vegetation shall be managed and boundaries will be marked. [Note: managed turf (e.g., playgrounds, regularly maintained open areas) is not an acceptable form of vegetation management.]

iv. Shall have a minimum contiguous area requirement of 10,000 square feet.

v. Must be forested or have a stable, natural ground cover.

2) Volume Reduction Method #3: Enhanced Swales.

a) This reduction may be taken when enhanced swales are used for water quality protection. Under the proposed method, a designer would be able to subtract the areas draining to an enhanced swale from total site area when computing water quality protection volume requirements. An enhanced swale can fully meet the water quality protection volume requirements for certain kinds of low-density residential development (see Volume Reduction Method #5). An added benefit is the post-development peak discharges will likely be lower due to a longer time of concentration for the site.

b) Rule: Subtract the areas draining to an enhanced swale from total site area when computing water quality protection volume requirements.

c) Criteria:

i. This method is typically only applicable to moderate or low density residential land uses (three dwelling units per acre maximum).

ii. The maximum flow velocity for water quality design storm shall be less than or equal to 1.0 feet per second.

iii. The minimum residence time for the water quality storm shall be five minutes.

iv. The bottom width shall be a maximum of six feet. If a larger channel is needed use of a compound cross section is required.

v. The side slopes shall be 3:1 (horizontal:vertical) or flatter.

vi. The channel slope shall be 3% or less.

3) Volume Reduction Method #4: Overland Flow Filtration/Groundwater Recharge Zones.

a) This reduction can be taken when "overland flow filtration/infiltration zones" are incorporated into the site design to receive runoff from rooftops or other small impervious areas (e.g., driveways, small parking lots, etc.). This can be achieved by grading the site to promote overland vegetative filtering or by providing infiltration or "rain garden" areas. If impervious areas are adequately disconnected, they can be deducted from total site area when computing the water quality protection volume requirements. An added benefit will be that the post-development peak discharges will likely be lower due to a longer time of concentration for the site.

b) Rule: If impervious areas are adequately disconnected, they can be deducted from total site area when computing the water quality protection volume requirements.

c) Criteria:

i. Relatively permeable soils (hydrologic soil groups A and B) should be present.

ii. Runoff shall not come from a designated hotspot.

iii. The maximum contributing impervious flow path length shall be 75 feet.

iv. Downspouts shall be at least 10 feet away from the nearest impervious surface to discourage "re-connections."

v. The disconnection shall drain continuously through a vegetated channel, swale, or filter strip to the property line or structural storm water control.

vi. The length of the "disconnection" shall be equal to or greater than the contributing length.

vii. The entire vegetative "disconnection" shall be on a slope less than or equal to 3%.

viii. The surface impervious area tributary to any one discharge location shall not exceed 5,000 square feet.

ix. For those areas draining directly to a buffer, reduction can be obtained from either overland flow filtration -or-stream buffers (See Method #2).

4) Volume Reduction Method #5: Environmentally Sensitive Large Lot Subdivisions.

a) This reduction can be taken when a group of environmental site design techniques are applied to low and very low density residential development (e.g., one dwelling unit per two acres [du/ac] or lower). The use of this method can eliminate the need for structural storm water controls to treat water quality protection volume requirements. This method is targeted towards large lot subdivisions and will likely have limited application.

b) Rule: Targeted towards large lot subdivisions (e.g., two acre lots and greater). The requirement for structural facilities to treat the water quality protection volume may be waived.

c) Criteria:

For single lot development:

i.	Total site impervious cover is less than 15%.
ii.	Lot size shall be at least two acres.
iii.	Rooftop runoff is disconnected in accordance with the criteria in Method #4.
iv.	Grass channels are used to convey runoff versus curb and gutter.

For multiple lots:

i.	Total impervious cover footprint shall be less than 15% of the area.
ii.	Lot areas should be at least two acres, unless clustering is implemented. Open space developments should have a minimum of 25% of the site protected as natural conservation areas and shall be at least a half-acre average individual lot size.
iii.	Grass channels should be used to convey runoff versus curb and gutter (see Method #3).
iv.	Overland flow filtration/infiltration zones should be established (see Method #4).

B. Stormwater infiltration practices.

(1) In selecting the appropriate infiltration BMPs, the Applicant shall consider the following:

(a) Permeability and infiltration rate of the site soils.

(b) Slope and depth to bedrock.

(c) Seasonal high water table.

(d) Proximity to building foundations and well heads.

(e) Erodibility of soils.

(f) Land availability and topography.

(g) Slope stability.

(h) Effects on nearby properties and structures.

(2) A detailed soils evaluation of the project site shall be performed to determine the suitability of infiltration BMPs. The evaluation shall be performed by a qualified professional, and at a minimum, address soil permeability, depth to bedrock and slope stability. The general process for designing the infiltration BMP shall be:

(a) Analyze hydrologic soil groups as well as natural and man-made features within the watershed to determine general areas of suitability for infiltration BMPs.

(b) Provide field testing data to determine appropriate percolation rate and/or hydraulic connectivity.

(c) Design infiltration BMPs for required stormwater volume based on field-determined capacity at the level of the proposed infiltration surface.

(3) Soil characteristics, as subject to the specific considerations below:

(a) Infiltration BMPs are particularly appropriate in hydrologic soil groups A and B, as described in the Natural Resources Conservation Manual TR-55.

(b) Low-erodibility factors ("K" factors) are preferred for the construction of basins.

(c) There must be a minimum depth of 48 inches between the bottom of any facility and the seasonal high water table and/or bedrock (limiting zones), except for infiltration BMPs receiving only roof runoff which shall be placed in soils having a minimum depth of 24 inches between the bottom of the facility and the limiting zone.

(d) There must be an infiltration and/or percolation rate sufficient to accept the additional stormwater load, and to drain completely as determined by field tests.

(e) The infiltration system shall have positive overflow controls to prevent storage within one foot of the finished surface or grade.

(f) Infiltration rates shall not be used the computing the storage volume of the infiltration system.

(g) Surface inflows shall be designed to prevent direct discharge of sediment into the infiltration system.

(4) The recharge volume provided at the site shall be directed to the most permeable hydrologic soil group available, except where other considerations apply such as in limestone geology.

(5) Any infiltration BMP shall be capable of completely infiltrating the impounded water within 48 hours. The 48-hour period is to be measured from the end of the 24-hour design storm.

(6) The Township may require additional analyses for stormwater management facilities proposed for susceptible areas such as:

(a) Strip mines.

(b) Storage areas for salt, chloride, other materials for winter deicing.

(c) Unstable Slopes.

(7) During the period of land disturbance, runoff shall be controlled prior to entering any proposed infiltration area. Areas proposed for infiltration BMPs shall be protected from sedimentation and compaction during the construction phase, so as to maintain their maximum infiltration capacity.

(8) Infiltration BMPs shall not be constructed nor receive runoff until the entire contributory drainage area to the infiltration BMP has received final stabilization.

(9) Infiltration facilities shall be selected based on suitability of soils and site conditions. Acceptable infiltration facilities include, but are not limited to: filter strips or stormwater filtering systems (for example bioretention facilities, sand filters), open vegetated channels (that is, dry swales and wet swales), infiltration trenches, dry wells, infiltration basins, porous paving systems, retention basins, wet extended detention ponds, riparian corridor management, riparian forested buffers, rooftop runoff management systems, and sand filters (closed or open).

(10) Where sediment transport in the stormwater runoff is anticipated to reach the infiltration system, appropriate permanent measures to prevent or collect sediment shall be installed prior to discharge to the infiltration system.

(11) All infiltration facilities shall be set back at least 15 feet from all structures with sub-grade elements (e.g., basements, foundation walls).

(12) All infiltration facilities that serve more than one lot and are considered a common facility shall have a drainage easement. The easement shall provide to the Township the right of access.

(13) If detailed infiltration study is required, the following guidance shall be followed:

(a) Soil evaluations shall be performed to determine the feasibility and extent to which infiltration systems can be used. The evaluation shall be performed by a qualified, licensed geologist, geotechnical/civil engineer or soil scientist and, at a minimum, address soil types, soil permeability, depth to bedrock, limitations of soils, presence/absence of carbonate geology susceptibility to subsidence and/or sinkhole formation and subgrade stability. The testing and evaluation should be completed at the preliminary design stage.

(b) Infiltration requirements shall be based on the portions of the site that are permeable prior to disturbance and the degree to which development will reduce the permeability of the site. Permeability of the site shall be determined based on the detailed evaluations described herein. Use of stormwater management facilities to retain stormwater for infiltration should be applied to all areas where the soils evaluation indicates favorable conditions. Areas generally not favorable for infiltration shall still be provided with an appropriate water quality practice.

(c) Soil infiltration tests shall be performed to an equivalent depth or elevation of the bottom of the proposed infiltration areas. These tests shall follow the procedures of percolation test holes as established by the ACHD for on-lot septic systems. The testing shall include a test pit and percolation test holes. The test hole shall be excavated to a depth so that the presence or absence of bedrock and/or seasonal high water table can be determined. A soil log describing the soils present in each test pit shall be performed. All test holes used for evaluating the percolation rate shall be pre-soaked in accordance with the procedures established by the ACHD. The location and number of test pits and percolation holes shall be determined based on the type(s) of stormwater management facilities being designed. Acceptability of infiltration rates shall be based on sound engineering judgment and recommended design considerations described in the design manuals listed in the references or other source material acceptable to the Township Engineer.

(14) The following design and construction standards shall be followed when planning and constructing infiltration BMPs.

(a) The lowest elevation of the infiltration area shall be at least two feet above the Seasonal High Water Table and bedrock.

(b) Roof drains and sump pumps shall discharge to infiltration or vegetated BMPs wherever feasible. Where roof drains are designed to discharge to infiltration facilities, they shall have appropriate measures to prevent clogging by unwanted debris (for example, silt, leaves and vegetation). Such measures shall include, but are not limited to, leaf traps, gutter guards and cleanouts.

(c) All infiltration facilities shall have appropriate positive overflow controls to prevent storage within one foot of the finished surface or grade, unless a specific amount of surface storage away from pedestrian and vehicular traffic is provided and such areas infiltrate the stored volume within 48 hours after the end of the 24-hour design storm.

(d) All infiltration facilities shall be designed to infiltrate the stored volume within 48 hours after the end of the 24-hour design storm.

(e) All surface inflows shall be treated to prevent the direct discharge of sediment into the infiltration practice; accumulated sediment reduces stormwater storage capacity and ultimately clogs the infiltration mechanism. No sand, salt or other particulate matter may be applied to a porous (pervious) surface for winter ice conditions.

(f) During site construction, all infiltration practice components shall be protected from compaction due to heavy equipment operation or storage of fill or construction material. Infiltration areas shall also be protected from sedimentation. Areas that are accidentally compacted or graded shall be remediated to restore soil composition and porosity. Adequate documentation to this effect shall be submitted for review by the Township Engineer. All areas designated for infiltration shall not receive runoff until the contributory drainage area has achieved final stabilization.

(g) The following procedures and materials shall be required during the construction of all subsurface facilities:

1) Excavation for the infiltration facility shall be performed with equipment that will not compact the bottom of the seepage bed/trench or like facility.

2) The bottom of the bed and/or trench shall be scarified prior to the placement of aggregate.

3) Only clean aggregate with documented porosity, free of fines, shall be allowed.

4) The tops and sides of all seepage beds, trenches, or like facilities shall be covered with drainage fabric. Fabric shall meet the specifications of PennDOT Publication 408, Section 735, Construction Class 1.

5) Perforated distribution pipes connected to centralized catch basins and/or manholes with the provision for the collection of debris shall be provided in all facilities. Where perforated pipes are used to distribute stormwater to the infiltration practice, stormwater shall be distributed uniformly throughout the entire seepage bed/trench or like facility.

C. Open vegetated channels.

(1) Open Vegetated Channels are conveyance systems that are engineered to also perform as water quality and infiltration facilities. Such systems can be used for the conveyance, retention, infiltration and filtration of stormwater runoff.

(2) Open Vegetated Channels primarily serve a water quality function (WQv), they also have the potential to augment infiltration. Examples of such systems include, but are not limited to: dry swales, wet swales, grass channels, and biofilters. Open Vegetated Channels are primarily applicable for land uses such as roads, highways, residential developments (dry swales only) and pervious areas.

(3) Open Vegetated Channels shall be designed to meet the following minimum standards:

(a) The channel shall be designed to safely convey the 10-year frequency storm event with a freeboard of at least 12 inches. Freeboard is the difference between the elevation of the design flow in the channel and the top elevation of the channel.

(b) The peak velocity of the runoff from the 10-year storm shall be non-erosive for the soil and ground cover provided in the channel.

(c) The longitudinal slope shall be no greater than 4%.

(d) Channels shall be trapezoidal in cross section.

(e) Channels shall be designed with moderate side slopes of four horizontal to one vertical. Flatter side slopes may be necessary under certain circumstances.

(f) The maximum allowable ponding time in the channel shall be less than 48 hours.

(g) Channels (for example, dry swales) may require an underdrain in order to function and dewater.

(h) Channels shall be designed to temporarily store the WQv within the system for a maximum period of 48 hours and a minimum period of one hour.

(i) Landscape specifications shall address the grass species, wetland plantings (if applicable), soil amendment and hydric conditions present along the channel.

(j) Accumulated sediment within the channel bottom shall be removed when 25% of the original volume has been exceeded. The channel shall be provided with a permanent concrete cleanout marker that indicates the 25% loss level.

(k) Check dams along the channel length may be warranted.

(l) The bottom of dry swales shall be situated at least two feet above the seasonal high water table.

(4) Additional design information for Open Vegetated Channels is available in Design of Roadside Channels with Flexible Linings, HEC 15, FHWA, September 2005.

D. Retention basins.

(1) Retention basins shall be designed to create a healthy ecological community with sufficient circulation of water to prevent the growth of unwanted vegetation and mosquitoes or other vectors. If circulation cannot be provided via natural means, then artificial aeration and circulation shall be provided. Care shall be taken to landscape retention basins in accordance with Section 165-106.4.

(2) The retention basin shall be of sufficient size to allow the appropriate aquatic community needed to maintain healthy pond ecology and avoid mosquitoes capable of carrying West Nile Virus and other diseases. The ACHD, Pennsylvania Fish and Boat Commission, the Natural Resource Conservation Service, the Pennsylvania Extension Service, or other qualified professional consultant shall be consulted during the design of these facilities in order to ensure the health of aquatic communities and minimize the risk of creating mosquito breeding areas.

(3) An outlet structure shall be designed to allow complete drainage of the pond for maintenance.

(4) The design of a retention basin shall include the determination of the proposed site's ability to support a viable permanent pool. The design shall take into account such factors as the available and required rate and quality of dry weather inflow, the stormwater inflow, seasonal and longer-term variations in ground water table, and impacts of potential pollutant loadings.

(5) Sediment storage volume equal to at least 20% of the volume of the permanent pool shall be provided.

(6) A sediment forebay with a hardened bottom shall be provided at each inlet into the retention basin. The forebay storage capacity shall at minimum be 10% of the permanent pool storage. The forebay shall be designed to allow for access by maintenance equipment for periodic cleaning. A permanent concrete cleanout maker shall be installed in the forebay to indicate the level where 25% for the forebay storage has been used.

(7) Emergency spillways shall be sized and located to permit the safe passage of stormwater flows from an unattenuated 100-year post-development storm with one foot of freeboard. The maximum velocities in vegetated spillways excavated in otherwise undisturbed soil shall be analyzed based upon the velocity of peak flow in the emergency spillway during an assumed clogged primary outlet condition. Where maximum velocities exceed design standards contained in the Engineering Field Manual for Conservation Practices (USDA, SCS, July 1984) suitable lining shall be provided. All emergency spillways placed on fill materials shall be lined. Lining for emergency spillways shall incorporate native colors and materials where possible including mono slab revetments, grass pavers, rip rap and native stone.

(8) Basin and pond embankments must be designed by a professional engineer registered in the Commonwealth of Pennsylvania. The design must include an investigation of the subsurface conditions at the proposed embankment location to evaluate settlement potential, groundwater impacts, and the need for seepage controls. The submittal of a geotechnical report from a geotechnical engineer for any embankment over 10 feet in effective height or posing a significant hazard to downstream property or life is required. The selection of fill materials must be subject to approval of the design engineer. Fill must be free of frozen soil, rocks over six inches, sod, brush, stumps, tree roots, wood, or other perishable materials. Embankment fills less than 10 feet in fill height must be compacted using compaction methods that would reasonably guarantee that the fill density is at least 90% of the maximum density as determined by standard proctor (ASTM-698). All embankment fills more than 10 feet in fill height must be compacted to at least 90% of the maximum density as determined by standard proctor (ASTM-698) and must have their density verified by field density testing. A PADEP Dam permit is required for embankments having; a maximum depth of water, measured from the upstream toe of the dam to the top of the dam at maximum storage elevation, of greater than 15 feet; and or for ponds having contributory drainage area of greater than 100 acres; and or for impoundments of greater than 50 acre-feet.

(9) The embankment's interior slope may not be steeper than 3:1. The exterior slope of the embankment may not exceed 2:1 (2 horizontal to one vertical).

(10) The minimum embankment width shall be four feet for embankments less than six feet in height, six feet if the embankment is between 6.1 feet and 9.9 feet in height and eight feet if the embankment is between 10 feet and 15 feet in height.

(11) Existing ponds or permanent pool basins can be used for stormwater management provided that it can be demonstrated that the ponds are structurally sound and meet the design requirements herein.

(12) Inlet structures and outlet structures shall be separated to the greatest extent possible in order to maximize the flow path through the retention basin.

(13) Retention basins shall be designed to provide a length-to-width ratio of at least 3L:1W as measured in plain view (for example, a ratio of 4L:1W is too narrow).

(14) The retention basin depth shall average three to six feet.

(15) Fencing of the facility is not required if the interior slope of the pond is 4H:1V or flatter and the design also includes a five-foot wide bench around the pond perimeter at an elevation one foot below the permanent water surface elevation.

(16) Any side slopes below the permanent water surface level shall not exceed 3H:1V. Interior side slopes above the permanent water surface level shall not exceed 3H:1V.

(17) Stabilization. Proper stabilization structures, including stilling basins, energy dissipators, and channel lining shall be constructed at the outlets of all retention basins and emergency spillways. The stabilization structures shall control water to: avoid erosion; reduce velocities of released water and direct water so that it does not interfere with downstream activities.

(18) Energy dissipators and/or level spreaders shall be installed to prevent erosion and/or initiate sheet flow at points where pipes or drainage ways discharge to or from basins. Level Spreaders shall be used only where the maximum slope between the discharge point and the waterway does not exceed 5%. Energy dissipators shall comply with criteria in Hydraulic Design of Energy Dissipators for Culverts and Channels, HEC 14, FHWA, July, 2006. Such facilities shall be both functional and harmonious with the surrounding environment; for example, native rock shall be used in constructing dissipators where practical.

(19) Discharge points. The minimum distance between a proposed basin discharge point (including the energy dissipator, etc.) and a downstream property boundary shall in no case be less than 15 feet. Where there is discharge onto or through adjacent properties prior to release to a stream, designers shall demonstrate how downstream properties are to be protected. The Township Engineer may require that the setback distance be increased based upon factors such as topography, soil conditions, the size of structures, the location of structures, and discharge rates. A drainage easement may also be required.

(20) Outlet structures. Outlet structures shall meet the following specifications:

(a) To minimize clogging and to facilitate cleaning and inspecting, outlet pipes shall have an internal diameter of at least 15 inches and a minimum grade of 1%.

(b) Bentonite plugs shall be provided on all outlet pipes within a constructed berm.

(c) All principal outlet structures shall be built using reinforced concrete with watertight construction joints.

(d) The use of architecturally treated concrete, stucco, painted surface or stone facade treatment shall be considered for enhancing the outlet structure. Such facilities shall be both functional and harmonious in design with the surrounding environment.

(e) Outlet pipes shall be constructed of reinforced concrete with rubber gaskets in conformance with AASHTO M170, M198 and M207, or smooth interior HDPE pipe in conformance with AASHTO M252 or M294.

(f) Basin outlet structures shall have childproof non-clogging trash racks over all design openings exceeding 12 inches in diameter except those openings designed to carry perennial stream flows. Periodic cleaning of debris from trash racks shall be included in the operation and maintenance plan.

(g) Anti-vortex devices, consisting of a thin vertical plate normal to the basin berm, shall be provided at the top of all circular risers or standpipes.

E. Detention basins.

(1) The landscape standards of Section 165-106.4 shall apply.

(2) The maximum inside side slopes shall not exceed three horizontal to one vertical (3H:1V). The minimum required slope for the basin bottom is 2%. A level bottom is acceptable, provided the designer demonstrates to the Township's satisfaction that the basin bottom will be landscaped with appropriate wetland vegetation pursuant to Section 165-106.4.4. In addition, Detention Basins of sufficient size and slope may serve other functions as well, including recreational uses which do not hinder or conflict with the function of the detention basin.

(3) Inlet structures. The inlet pipe invert into a basin shall be six inches above the basin floor or lining so that the pipe can adequately drain after rainstorms. Inlets shall discharge into areas of the basin that slope toward the outlet structure.

(4) Inlet structures and outlet structures shall be separated to the greatest extent possible in order to maximize the flow path through the retention basin.

(5) Low flow channels. Low flow channels constructed of concrete or asphalt are not permitted. Where low flow channels are necessary, they shall be composed of a natural or bioengineered material. Low flow channels shall be designed to promote water quality and slow the rate of flow through the basin. Low flow channels may also be designed to infiltrate where practical.

(6) Outlet structures. Outlet structures shall meet the following specifications:

(a) To minimize clogging and to facilitate cleaning and inspection, outlet pipes shall have an internal diameter of at least 15 inches and a minimum grade of 1%.

(b) Bentonite plugs shall be provided on all outlet pipes within a constructed berm.

(c) All principal outlet structures shall be built using reinforced concrete with watertight construction joints.

(d) The use of architecturally treated concrete, stucco, painted surface or stone facade treatment shall be considered for enhancing the outlet structure. Such facilities shall be both functional and harmonious in design with the surrounding environment.

(e) Outlet pipes shall be constructed of reinforced concrete with rubber gaskets in conformance with AASHTO M170, M198 and M207, or smooth interior HDPE pipe in conformance with AASHTO M252 or M294.

(f) Energy dissipation facilities that convert concentrated flow to uniform shallow sheet flow shall be used where appropriate.

(g) Basin outlet structures shall have childproof non-clogging trash racks over all design opening exceeding 12 inches in diameter except those openings designed to carry perennial stream flows.

(h) Anti-vortex devices, consisting of a thin vertical plate normal to the basin berm, shall be provided at the top of all circular risers or standpipes.

(7) Emergency spillways shall be sized and located to permit the safe passage of stormwater flows from an unattenuated 100-year post-development storm with one foot of freeboard. The maximum velocities in vegetated spillways excavated in otherwise undisturbed soil shall be analyzed based upon the velocity of peak flow in the emergency spillway during an assumed clogged primary outlet condition. Where maximum velocities exceed design standards contained in the Engineering Field Manual for Conservation Practices (USDA, SCS, July 1984) suitable lining shall be provided. In general, emergency spillways should not be located in fill areas; all such facilities placed on fill materials shall be lined. Lining for emergency spillways shall incorporate native colors and materials where possible, including mono slab revetments, grass pavers, rip rap and native stone.

(8) Basin and pond embankments must be designed by an Engineer. The design must include an investigation of the subsurface conditions at the proposed embankment location to evaluate settlement potential, groundwater impacts, and the need for seepage controls. The submittal of a geotechnical report from a geotechnical engineer for any embankment over 10 feet in effective height or posing a significant hazard to downstream property or life is required. The selection of fill materials must be subject to approval of the design engineer. Fill must be free of frozen soil, rocks over six inches, sod, brush, stumps, tree roots, wood, or other perishable materials. Embankment fills less than 10 feet in fill height must be compacted using compaction methods that would reasonably guarantee that the fill density is at least 90% of the maximum density as determined by standard proctor (ASTM-698). All embankment fills more than 10 feet in fill height must be compacted to at least 90% of the maximum density as determined by standard proctor (ASTM-698) and must have their density verified by field density testing. A PADEP Dam permit is required for embankments having; a maximum depth of water, measured from the upstream toe of the dam to the top of the dam at maximum storage elevation, of greater than 15 feet; and or for ponds having contributory drainage area of greater than 100 acres; and or for impoundments of greater than 50 acre-feet.

(9) The embankment's interior slope may not be steeper than 3:1 (3 horizontal to one vertical). The exterior slope of the embankment may not exceed 2:1 (2 horizontal to one vertical).

(10) The minimum embankment width shall be four feet for embankments less than six feet in height, six feet if the embankment is between 6.1 feet and 9.9 feet in height and eight feet if the embankment is between 10 feet and 15 feet in height.

(11) Fencing of the facility is not required if the interior slope of the pond is 4:1 or flatter.

(12) Freeboard. Freeboard is the difference between the elevation of the design flow in the emergency spillway (usually the 100-year peak elevation) and the top elevation of the settled basin embankment (that is, top of berm). The minimum freeboard shall be one foot.

(13) Energy dissipators and/or level spreaders shall be installed to prevent erosion and/or initiate sheet flow at points where pipes or drainage ways discharge to or from basins. Level Spreaders shall be used only where the maximum slope between the discharge point and the waterway does not exceed 5%. Energy dissipators shall comply with criteria in Hydraulic Design of Energy Dissipators for Culverts and Channels, HEC 14, FHWA, July, 2006. Such facilities shall be both functional and attractive; for example, native rock shall be used in constructing dissipators where practical.

(14) Stabilization. Proper stabilization structures, including stilling basins, energy dissipators, and channel lining, shall be constructed at the outlets of all basins and emergency spillways. The stabilization structures shall control water to avoid erosion, reduce velocities of released water and direct water so that it does not interfere with downstream activities.

(15) Discharge points. The minimum distance between a proposed basin discharge point (including the energy dissipator, etc.) and a downstream property boundary shall in no case be less than 15 feet. Where there is discharge onto or through adjacent properties prior to release to a stream, designers shall demonstrate how downstream properties are to be protected. The Township Engineer may require that the setback distance be increased based upon factors such as topography, soil conditions, the size of structures, the location of structures, and discharge rates. A drainage easement may also be required.

(16) A sediment forebay with a hardened bottom shall be provided at each inlet into the detention basin. The forebay storage capacity shall at minimum be 10% of the permanent pool storage. The forebay shall be designed to allow for access by maintenance equipment for periodic cleaning.

F. Conveyance systems (open channels, drainageways, and storm sewers).

(1) Applicants are encouraged to design conveyance systems that encourage infiltration and improve water quality wherever practicable.

(2) Wherever conveyance channels are necessary, drainage shall be maintained by an open channel with landscaped banks designed to carry the 10-year, 24-hour stormwater runoff from upstream contributory areas. The Township Engineer may increase the design storm, as conditions require. All open channels shall be designed with one foot of freeboard above the design water surface elevation of the design runoff condition.

(3) Flood relief channels shall be provided and designed to convey the runoff from the 100-year, 24-hour storm, such that a positive discharge of this runoff to an adequate receiving stream or conveyance system occurs without allowing this runoff to encroach upon other properties.

(4) Manholes and/or inlets shall not be spaced more than 300 feet apart for pipe sizes up to 24 inches in diameter and not more than 450 feet apart for larger pipe sizes.

(5) Where drainage swales are used in lieu of or in addition to storm sewers, they shall be designed to carry the required runoff without erosion and in a manner not detrimental to the properties they cross. Drainage swales shall provide a minimum grade of 2% but shall not exceed a grade of 9%. Drainage swales used strictly for conveyance are not the same as Open Vegetated Channels. Design standards for Open Vegetated Channels are provided under Section 165-106.3.C of this Chapter.

(6) Street curbing for the purpose of stormwater conveyance is discouraged. On streets that must contain curbing, storm sewers shall be placed in front of the curbing. To the greatest extent possible, storm sewers shall not be placed directly under curbing. At curbed street intersections, storm inlets shall be placed in the tangent section of the road.

(7) Use of grassed swales or open vegetated swales in lieu of curbing to convey, infiltrate and/or treat stormwater runoff from roadways is encouraged. Inlets shall be placed at the center of the shoulder swale draining the street and shall be located no closer than four feet from the edge of the cartway.

(8) All storm sewers, drainage swales, channels, permanent detention/retention basins and/or other stormwater management facilities providing stormwater control for other than a single lot shall be located within a defined drainage easement that allows proper legal access and maintenance vehicle access. This drainage easement shall be a minimum of 20 feet wide.

(9) No property owner shall obstruct or alter the flow, location or carrying capacity of a stream, channel or drainage swale to the detriment of any other property owner, whether upstream or downstream. All subdivision and/or land development plans containing streams, channels, drainage swales, storm sewers or other conveyance systems that cross property boundaries, existing or proposed, or whose discharge crosses such boundaries shall contain a note stating the above.

(10) Water quality inlets. Storm drainage systems that collect runoff from parking areas and/or loading areas exceeding 10,000 square feet of impervious coverage and discharge to stormwater management systems, including surface or subsurface infiltration systems, shall have a minimum of one water quality inlet per each acre of drainage area. The purpose of water quality inlets is to remove oil, grease, and heavy particulates or total suspended solids, hydrocarbons and other floating substances from stormwater runoff. Methods other than water quality inlets may be permitted if the Applicant demonstrates to the Township's satisfaction that any such alternative will be as effective and as easily maintained. Periodic cleaning of these systems shall be addressed in the Operation and Maintenance Plan submitted to the Township.

4. Landscaping of stormwater management facilities. Stormwater management facilities shall be landscaped in accordance with the following standards.

A. Landscaping shall be required in and around all constructed stormwater management facilities with a minimum surface area of 1,000 square feet for the purposes of:

(1) Assisting in the management of stormwater;

(2) Stabilizing the soil within such facilities to minimize and control erosion;

(3) Enhancing the visual appearance of such facilities; and

(4) Mitigating maintenance problems commonly associated with the creation of such facilities.

B. A planting plan and planting schedule shall be submitted in accordance with the following:

(1) Wet meadows including floors of stormwater management facilities.

(a) Wet meadows and floors of stormwater management facilities shall be planted with non-invasive plants native to western Pennsylvania such as wildflowers and non-invasive grasses, the intent being to create a mixed meadow of such plantings, where appropriate. Selection of plantings shall be based on whether the area in question is usually well drained or permanently wet and whether the area will be used for recreation purposes. No woody plants shall be planted within the saturated zone (phreatic line) of a stormwater management practice or on a berm constructed for impounded water.

(b) Seeding by drills, corrugated rollers, cyclone or drop seeders or hand seeding of such areas is preferred; however, hydroseeding followed by hydromulching can be used on wet ground and steep slopes.

(c) Fertilizers, as a nutrient supplement, shall not be used unless it is documented that soil conditions warrant such use and nutrient applied does not exceed plant uptake. Soil for planting of wildflowers shall contain not less than 3% or more than 10% organic matter, as determined by an agricultural chemist, with certification of the test before planting.

(d) Seeding shall take place either between April 1 and May 15 or between September 1 and October 15. Planting areas shall be soaked to maintain a consistent level of moisture for at least four to six weeks after planting. For seeding recommendations, reference the DEP's E&S Pollution Control Program Manual.

(e) Once established, a single annual mowing when plants are dormant should be sufficient to maintain a wet meadow and/or floor of a stormwater management practice.

(2) Wet edges that remain wet all or most of the year shall be planted with wildflowers, grasses and shrubs. Plants to be located on rims or banks, which remain dry most of the year, shall be planted with species tolerant of dry soil conditions.

(3) Wooded areas.

(a) Where stormwater management facilities adjoin wooded areas, trees and shrubs shall be selected and planted outside the practice so as to blend with existing surroundings.

(b) Plantings in such areas shall be of sufficient density to eliminate the need for mowing.

(c) It is recommended that clusters of trees and shrubs be planted around stormwater management facilities but well away from outfalls and any constructed berms, where applicable, to provide for wildlife habitat, wind control and buffering and screening.

(d) Vegetation shall be planted during appropriate times of the year, predominantly between late March and mid-May or from early October until evidence of ground freezing, depending upon the species selected. Most deciduous trees and shrubs can be planted in either spring or fall. Evergreens are best planted in late summer or early fall.

(4) Slopes.

(a) Where slopes are gentle, a mixture of meadow grasses and wildflowers (for wet meadows) shall be planted.

(b) On steep slopes as defined by the Zoning Ordinance (Chapter 208), dense spreading shrubs (shrubs tolerant of dry soils) shall be planted. Heavy mat mulch shall be used during the period of establishment.

(c) No woody plant materials or trees shall be located on a constructed or natural berm acting as the impoundment structure of a stormwater management practice. Trees shall be located downstream of an impoundment berm a sufficient distance from the toe of the constructed slope to assure that the toe of the slope is outside the dripline of the species planted at maturity but in no case less than 15 feet.

(5) In cases where stormwater management facilities are to be located in proximity to wetlands or waterways, the Applicant's planting plan and schedule shall consider the sensitive conditions existing therein and be modified accordingly to reflect existing flora.

(6) Stormwater management facilities shall be screened in a manner which complements the existing landscape and provides sufficient access for maintenance.

5. Riparian (stream) buffer requirements. In order to protect and improve water quality, a Riparian Buffer Easement shall be created and recorded as part of any subdivision or land development that encompasses a Riparian Buffer. The intent of this Chapter in establishing a Riparian Buffer is to protect and improve stream water quality. The Riparian Buffer is intended to slow overland flow to the stream through the presence of native grasses, trees and shrubs, allowing infiltration/groundwater recharge; causing deposition of sediment, nutrients, pesticides, and other pollutants in the buffer rather than in the stream; and reducing erosion by providing stream bank stabilization. The trees provide shade for streams; keeping waters cooler and reducing evaporation.

A. A minimum riparian buffer width of 50 feet landward in each direction from the top of stream banks is required for all waterways having both a defined bank and a contributing watershed area of greater than 100 acres.

B. A minimum riparian buffer width of 35 feet landward in each direction from the top of stream bank is required for smaller waterways having a contributing watershed area of less than 100 acres and greater than 10 acres.

C. The riparian buffer area should be maintained in a natural state.

D. When wetland(s) extend beyond the edge of the required buffer width, the buffer shall be adjusted so that the buffer consists of the extent of the wetland plus a 25-foot zone extending beyond the wetland edge.

E. Riparian buffer averaging may be applied to account for encroachments such as road crossings. The following criteria must be met in order to utilize buffer averaging on a development site:

(1) Buffer averaging is required for water quality buffers that have stream crossings.

(2) An overall average buffer width of at least 50 feet, or 35 feet if watershed is between greater than 10 but less than 100 acres, must be achieved within the boundaries of the property to be developed. Riparian buffer corridors on adjoining properties cannot be included with buffer averaging on a separate property, even if owned by the same property owner.

(3) The average width must be calculated based upon the entire length of stream bank that is located within the boundaries of the property to be developed. When calculating the buffer length, the natural stream channel should be followed.

(4) Riparian 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 stream, but must be applied to both sides of the stream independently.

(5) On each stream bank, the total width of the buffer shall not be less than 25 feet at any location, except at approved stream crossings. Those areas of the buffer having a minimum width of 25 feet (or less at approved stream crossings) can comprise no more than 50% of the buffer length.

(6) Minimum management requirements for riparian buffers.

(a) No use or construction within the Riparian Buffer shall be permitted that is inconsistent with the intent of the Riparian Buffer as described in 165-106.5.

(b) Existing native vegetation shall be protected and maintained within the Riparian Buffer Easement.

(c) Whenever practicable, invasive vegetation shall be actively removed and the Riparian Buffer Easement shall be planted with native trees, shrubs and other vegetation to create a diverse native plant community appropriate to the intended ecological context of the site.

F. The Riparian Buffer Easement shall be enforceable by the Municipality and shall be recorded in the appropriate County Recorder of Deeds Office, so that it shall run with the land and shall limit the use of the property located therein. The easement shall allow for the continued private ownership and shall count toward the minimum lot area required by Zoning, unless otherwise specified in the municipal Zoning Ordinance.

G. Any permitted use within the Riparian Buffer Easement shall be conducted in a manner that will maintain the extent of the existing 100-year floodplain, improve or maintain the stream stability, and preserve and protect the ecological function of the floodplain.

H. Stormwater drainage pipes shall be permitted within the Riparian Buffer Easement, but they shall cross the Easement in the shortest practical distance. Other structural stormwater management facilities are not permitted within the Riparian Buffer Easement.

I. The following conditions shall apply when public and/or private recreation trails are permitted by the Municipality within Riparian Buffers:

(1) It is preferred that trails be designed to be permeable and for non-motorized use only; however, impermeable trails are permitted provided they have adequate drainage.

(2) Trails shall be designed to have the least impact on native plant species and other sensitive environmental features.

J. Septic drainfields and sewage disposal systems shall not be permitted within the Riparian Buffer Easement and shall comply with setback requirements established under 25 Pa. Code Chapter 73.

K. Underground utilities shall be permitted within the Riparian Buffer Easement; however, work shall be performed to minimize disturbance area and removal of trees. Restoration within the Riparian Buffer Easement shall be with native species of trees, grasses, and other plantings. One tree shall be planted for each tree removed and the restoration shall be designed by a Registered Professional with the requisite experience. Aboveground utilities shall only be permitted to cross the Easement perpendicular to the Easement or in the shortest practical distance. Existing utilities may remain and be maintained as required.

L. Stream buffers should be illustrated on all grading and erosion and sedimentation control plans. The defined stream buffer location should be properly recorded. The recording should provide a plan illustrating the stream buffer location, width and the requirement that it be maintained in a natural state.

§ 165-107 Operation and maintenance responsibilities.

1. General responsibilities.

A. The owner of stormwater management facilities, as defined and/or set forth in the Operation and Maintenance Agreement referenced in Section 165-107.4, shall be responsible for the proper operation and maintenance of those facilities during and after construction. An Operation and Maintenance Plan consistent with the requirements of Section 165-107.3 shall be prepared for review and approval by the Township Engineer and shall be executed and signed by the Township Engineer and Applicant.

B. The owner of the stormwater management facilities, as defined and/or set forth in the Operation and Maintenance Agreement referenced in Section 165-107.4, shall be responsible for the proper installation and function of those facilities in accordance with the approved Stormwater Management Plan. All temporary soil erosion and sedimentation control measures shall be removed or converted to their permanent configuration in accordance with an approved erosion and sedimentation control plan. This requirement in no way precludes the authority of the ACCD to determine when sufficient stabilization has occurred on a site in order to convert to the permanent stormwater management facilities.

C. Dedication and acceptance of stormwater management facilities.

(1) After completion of construction of stormwater management facilities shown on an approved subdivision and/or land development plan, the Applicant may submit a written offer of such stormwater management facilities for dedication to the Township or other authorized public entity. Said offer shall include a deed of dedication covering said facilities together with satisfactory proof establishing an Applicant's clear title to said property. Such documents are to be filed with the Township Secretary for review by the Township Solicitor. Deeds of dedication for stormwater management facilities may be accepted by resolution of the Township, at the Township's sole discretion, but the Township is under no obligation to accept an offer of dedication.

(2) The Township may require that stormwater management facilities remain undedicated, with operation and maintenance the responsibility of individual lot owners or a homeowners association or similar entity, or an organization capable of carrying out maintenance responsibilities.

(3) Regardless of ownership, the Applicant shall submit an actual "as built" plan to the Township for the stormwater management facilities required by the approved Stormwater Management Plan. The "as built" plan shall show all final design specifications for all permanent stormwater management facilities including, but not limited to, pipe material and diameter, inlet, outlet and overflow elevations, two-foot contours for all detention/retention basins and drainage swales and a comparison of "as-built" capacities compared to the capacities of the approved design facilities and shall be prepared and certified by an Engineer. The "as built" plan shall be based on an actual field survey performed by a professional land surveyor licensed as such by the Commonwealth of Pennsylvania. The surveyor shall certify as to the accuracy of the plan. The "as built" plan shall be submitted to the Township for review and approval by the Township Engineer. The "as-built" plan(s) shall be submitted to the Township in a digital format or formats approved by the Township.

2. Ownership and maintenance. All stormwater management facilities identified within an approved Stormwater Management Plan shall be owned and maintained by one, or a combination of, the following entities:

A. Private ownership.

(1) Where individual on-lot stormwater management facilities are proposed, the subdivision and/or land development plan shall contain a note in a form acceptable to the Township Solicitor designating the entity responsible for operation and maintenance of the on-lot facilities consistent with an approved Operation and Maintenance Plan and, in the event that the responsible person or entity fails to do so, granting to the Township the right but not the duty to enter upon the premises to repair or restore said facilities, to charge and assess the costs thereof to the owner, including reasonable attorney's fees, and to enforce said charges and assessments by lien upon the property. In addition, the deed for each lot shall contain a perpetual covenant binding the grantee and all successors in interest designating the responsibility for operation and maintenance of the on-lot facilities essentially in the following form and otherwise acceptable to the Township Solicitor:

"Under and subject, to the following conditions and restrictions: Prior to any Earth Disturbance for which stormwater management facilities are required by the Township, Grantee shall construct the permanent stormwater management facilities as shown on the stormwater management plan (the "Plan") prepared by [__NAME__], P.E., dated [__DATE__] and last revised [__DATE__] and approved by the Township; thereafter, the Grantee, his heirs, executors, administrators, successors and assigns ("Owner"), at his sole cost and expense, shall operate, maintain and repair said stormwater management facilities on the lot in accordance with said Plan, so that the facilities shall at all times continue to operate and function in the same manner and capacity as they were designed. In the event of the failure of the Owner to comply with these conditions and restrictions, the Township may have said stormwater management facilities repaired or restored as required, and any costs thereof, including reasonable attorney's fees, shall be assessed to the Owner; said assessment shall be a charge and a continuing lien upon the property herein.

(2) In addition to the above, developers of parcels with more than one dwelling unit shall record with the Allegheny County Department of Real Estate a declaration of covenants and restrictions in a form satisfactory to the Township Solicitor describing the responsibility for operation and maintenance of the on-lot facilities, consistent with an approved Operation and Maintenance Plan, prior to the sale of any individual lots. The terms of this covenant and restriction shall run with the land and be binding upon the grantees of each lot within the subdivision, his, her or their heirs, administrators, successors or assigns.

B. Homeowners or condominium association ownership.

(1) Where a homeowners' association or condominium association (collectively, the "association") is created to own and manage common facilities, the subdivision and/or land development plan shall contain a note in a form satisfactory to the Township Solicitor designating the entity responsible for construction and/or maintenance of the stormwater management facilities consistent with an approved Operation and Maintenance Plan and, in the event that the responsible entity fails to do so, granting to the Township the right but not the duty to enter upon the premises to repair or restore said facilities, to charge and assess the costs thereof, plus reasonable attorney's fees, to each owner of property within the development and to enforce said charges and assessments by lien upon each property within the development. In addition, the developer shall record with the Allegheny County Department of Real Estate a declaration of covenants in a form satisfactory to the Township Solicitor setting forth the rights and responsibilities of the association for operation and maintenance of the stormwater management facilities, prior to the sale of individual lots. The terms of this covenant and restriction shall run with the land and be binding upon the grantees of each lot within the subdivision, his, her or their heirs, administrators, successors and assigns.

C. Public entity ownership.

(1) Where the Township or other authorized public entity has accepted an offer of dedication of the permanent stormwater management facilities, said public entity shall be responsible for operation and maintenance of the stormwater maintenance facilities. Public entity ownership notwithstanding, the Applicant is required to prepare a Stormwater Management Plan and an Operation and Maintenance Plan, as defined herein. Upon approval of the stormwater management facilities by the Township, the Applicant shall provide a lump sum long-term maintenance payment to the Township, to be reserved and used at any time by the Township only for costs of operation and maintenance of the dedicated facilities, as follows:

(a) Long-term maintenance payment. The long-term maintenance payment shall be in an amount equal to the present value of operation and maintenance costs for the facilities for a 10-year period. The long-term maintenance payment shall be based on a 10-year cost estimate prepared by the Applicant's Engineer and reviewed and approved by the Township Engineer. The amount of the payment shall include all costs of operation and maintenance which shall include but not be limited to, typical operation and maintenance costs as well as costs such as landscaping and planting, and construction of any kind associated with the use, benefit and enjoyment of the facilities by the owners. In particular, a description of routine facility operation and day-to-day management requirements and a description of projected maintenance actions and schedules necessary to ensure proper operation of stormwater management facilities shall be submitted for review and approval to the Township Engineer.

(b) Documentation. The terms of the long-term maintenance payment shall be documented as part of the Stormwater Management Plan and the Operation and Maintenance Plan.

3. Operation and Maintenance Plan. An Operation and Maintenance Plan shall be prepared by an Engineer which identifies the ownership, operation and maintenance responsibilities and as-built conditions for all stormwater management facilities. Security for such operation and maintenance shall be established in the Operation and Maintenance Agreement referenced in Section 165-107.4.A. At a minimum, the Operation and Maintenance Plan shall include the following:

A. Any obligations concerning perpetuation and/or maintenance of natural drainage or infiltration facilities, and other facilities identified within the Stormwater Management Plan. Ownership of and responsibility for operation and maintenance of stormwater management facilities, including names and contact information, shall be required.

B. A description of the permanent stormwater management facilities on the site, explaining how each facility is intended to function and operate over time. All drainage and access easements shall be depicted and any site restrictions to be recorded against the property shall be identified on the recorded plan. All such easements and restrictions shall be perfected to run with the land and be binding upon the landowner and any successors in interest.

C. A description of the actions, budget and schedule for operating and maintaining the stormwater management facilities. This description should be written in a clear manner, consistent with the knowledge and understanding of the intended user.

D. A general description of operation and maintenance activities and responsibilities for facilities held in common or on-lot, including but not limited to, lawn care, vegetation maintenance, clean out of accumulated debris and sediment (including from grates, trash racks, inlets, etc.), liability insurance, maintenance and repair of stormwater management facilities, landscaping and planting, payment of taxes and construction of any kind associated with the use, benefit and enjoyment of the facilities by the owners. In particular, a description of routine facility operation and day-to-day management requirements (as needed) and a description of routine maintenance actions and schedules necessary to ensure proper operation of stormwater management facilities shall be submitted.

E. Assurances that no action will be taken by any lot owner to disrupt or in any way impair the effectiveness of any stormwater management system, setting forth in deed restrictions the ability of the Township to take corrective measures if it is determined at any time that stipulated permanent stormwater management facilities have been eliminated, altered, or improperly maintained, including the ability of the Township to cause the work to be done and lien all costs including reasonable attorney's fees against the property should the required corrective measures not be taken by the lot owner, following written notification, within a period of time set by Township Engineer.

F. Parties responsible for the long term operation and maintenance of stormwater management facilities shall make records of the installation and of all maintenance and repairs, and shall retain the records for at least 10 years. These records shall be submitted to the Township as established by the Operation and Maintenance Plan or as otherwise required by the Township.

4. Operations and Maintenance Agreement.

A. Prior to a developer and/or landowner commencing grading or construction activities related to the Stormwater Management Plan, the developer and/or landowner shall execute an Operations and Maintenance Agreement, in a form acceptable to the Township Solicitor, containing provisions to guarantee and secure the proper operation and maintenance of the stormwater management facilities. This Operation and Maintenance Agreement may be referred to as the Stormwater Management Agreement. A standard form of this Operation and Maintenance Agreement may be adopted from time to time by resolution of the Township Board of Supervisors.

B. The owner of any land upon which permanent stormwater management facilities and/or BMPs will be placed, constructed or implemented, as described in an approved Stormwater Management Plan and the Operations and Maintenance Plan, shall record the following documents in the Office of the Recorder of Deeds for Allegheny County, within 15 days of approval of the Operations and Maintenance Plan by the Township:

(1) The Operations and Maintenance Plan, or a summary thereof;

(2) Operation and Maintenance Agreement referenced in Section 165-107.4.A above; and

(3) Access and/or drainage Easements.

C. The Township may suspend or revoke any approvals granted for the project site upon discovery of the failure of the owner to comply with Section 165-107.4.A or the Operation and Maintenance Agreement referenced in Section 165-107.4.A of this Chapter.

§ 165-108 Plan submission, review and review fees.

1. Plan submission. The Township shall require receipt of a complete plan, as specified in this Chapter.

A. Copies of the Stormwater Management Plan shall be submitted and distributed as follows:

(1) Two copies to the Township accompanied by the requisite application fee and deposit pursuant to Section 165-108.5.

(2) One copy to the ACCD (when requested by the District).

(3) One copy to the Township Engineer.

2. Review.

A. The Township Engineer shall review the Stormwater Management Plan for consistency with this Chapter. Any Stormwater Management Plan found incomplete shall not be accepted for review and shall be returned to the Applicant.

B. The Township Engineer shall review the Stormwater Management Plan for any subdivision or land development against the provisions of the Subdivision and Land Development Ordinance (Chapter 174) not superseded by this Chapter.

C. When required by regulation, the ACCD shall review and approve the Erosion & Sedimentation Control Plan for consistency with PADEP's regulations.

D. For activities regulated by this Chapter, the Township Engineer shall notify the Applicant and the Township, whether the Stormwater Management Plan is consistent with this Chapter.

(1) Should the Stormwater Management Plan be determined to be consistent with this Chapter, the Township Engineer shall forward an approval letter to the Township Secretary who will then forward a copy to the Applicant.

(2) Should the Stormwater Management Plan be determined to be inconsistent with this Chapter, the Township Engineer shall forward a denial letter to the Township Secretary who will then forward a copy to the Applicant. The denial letter shall cite the reason(s) and specific sections of this Chapter for the denial. Denial may be due to inadequate information to make a reasonable judgment as to compliance with the requirements of this Chapter. Any denied Stormwater Management Plans may be revised by the Applicant and resubmitted consistent with this Chapter.

E. For Regulated Activities specified in Section 165-104 of this Chapter which require a building permit, the Township Engineer shall notify the Township Building Code Official in writing, within a time frame consistent with Chapter 52 of the Marshall Township Code of Ordinances, Construction Code, as amended, whether the Stormwater Management Plan is consistent with this Chapter and forward a copy of the approval/denial letter to the Applicant. Any denied Stormwater Management Plan may be revised by the Applicant and resubmitted consistent with this Chapter.

F. For regulated activities under this Chapter that require an NPDES Permit Application, the Applicant shall forward a copy of the Township Engineer's letter stating that the Stormwater Management Plan is consistent with this Chapter to the ACCD. PADEP and the ACCD may consider the Township Engineer's review comments in determining whether to issue a permit.

G. No building permits shall be issued for any Regulated Activity specified in Section 165-104 of this Chapter if the Stormwater Management Plan has been found to be inconsistent with this Chapter, as determined by the Township Engineer, or without considering the comments of the Township Engineer. All required permits from PADEP must be obtained prior to issuance of a building permit.

H. The Applicant shall be responsible for completing record drawings of all stormwater management facilities included in the approved Stormwater Management Plan. The record drawings and an explanation of any discrepancies with the design plans shall be submitted to the Township Engineer for final approval. In no case shall the Township approve the record drawings until the Township receives a copy of an approved PennDOT Highway Occupancy Permit, NPDES Permit, and any other applicable permits or approvals, including such permits and approvals from PADEP or the ACCD. The above permits and approvals must be based on the record drawings. The record drawings must include copies of all applicable permits and approvals.

I. The Township's approval of a Stormwater Management Plan shall be valid for a period not to exceed five years commencing on the date that the Township approves the Stormwater Management Plan. If stormwater management facilities included in the approved Stormwater Management Plan have not been constructed, or if constructed and record drawings of these facilities have not been approved within this time period, then the Township may consider the Stormwater Management Plan denied and may revoke any and all permits. Stormwater Management Plans that are considered denied by the Township shall be resubmitted in accordance with Section 165-108.4 of this Chapter.

3. Modification of plans. A modification to a Stormwater Management Plan under review by the Township for a development site that involves a change in stormwater management facilities or techniques, or that involves the relocation or re-design of stormwater management facilities, or that is necessary because soil or other conditions are not as stated on the Stormwater Management Plan as determined by the Township Engineer, shall require a resubmission of a modified Stormwater Management Plan consistent with this Chapter and shall be subject to review under this Chapter.

4. Resubmission of disapproved stormwater plans. A denied Stormwater Management Plan may be resubmitted, provided that it includes revisions addressing the grounds for denial and the Township Engineer's concerns in the written denial letter referenced under Section 165-108.5 of this Chapter. Any such resubmittal shall be subject to review as specified in Section 165-108 of this Chapter. The applicable Township application fee and deposit pursuant to Section 165-108.2 must accompany a resubmission of a denied Stormwater Management Plan.

5. Fees.

A. Application fees and deposits. The Township Board of Supervisors shall establish, from time to time by resolution, application fees and deposits to be paid by the applicant/developer at the time of filing the relevant application under this Chapter.

B. Review fees and expenses. The applicant/developer shall reimburse the Township for all fees and expenses incurred by the Township related to a Stormwater Management Plan and/or the review of any application under this Chapter, including but not limited to the reasonable and necessary charges by the Township Engineer and/or Township Solicitor for review and report on an application and/or Stormwater Management Plan under this Chapter and the inspection of improvements related thereto.

6. Authorization to construct and permit term of validity.

A. The Municipality's approval of an SWM Site Plan authorizes the regulated activities contained in the SWM Site Plan for a maximum term of validity of five years following the date of approval. The Municipality may specify a term of validity shorter than five years in the approval for any specific SWM Site Plan. Terms of validity shall commence on the date the Municipality signs the approval for an SWM Site Plan. If an approved SWM Site Plan is not completed according to Section 165-108.2 within the term of validity, then the Municipality may consider the SWM Site Plan disapproved and may revoke any and all permits. SWM Site Plans that are considered disapproved by the Municipality shall be resubmitted in accordance with Section 165-108.4 of this Chapter.