[HISTORY: Adopted by the Council of the Municipality of Murrysville 5-18-1992 by Ord. No. 321-92; amended in its entirety 2-17-2016 by Ord. No. 942-16. Subsequent amendments noted where applicable.]
GENERAL REFERENCESAttachment 1 - Stormwater Management Operations and Maintenance Agreement
Uniform construction codes — See Ch. 96.
Construction of roads and streets — See Ch. 97.
Drainage — See Ch. 102.
Grading, excavations and filling — See Ch. 124.
Mosquito breeding areas — See Ch. 152.
Sewers — See Ch. 193.
Erosion and sedimentation control — See Ch. 197.
Streets and sidewalks — See Ch. 199.
Subdivision and land development — See Ch. 201.
Water — See Ch. 215.
Zoning — See Ch. 220.
These regulations are adopted and implemented to achieve the following general purposes and objectives:
To manage and control stormwater runoff resulting from land alteration and disturbance activities in accordance with the watershed stormwater management plans adopted pursuant to the Pennsylvania Storm Water Management Act (Act 167 of 1978, as amended).
Editor's Note: See 32 P.S. § 680.1 et seq.
To reduce and minimize the volume of stormwater runoff from developed sites.
To utilize and preserve the desirable existing natural drainage patterns and to preserve the flood-carrying capacity of the streams.
To encourage natural infiltration of rainfall to preserve groundwater supplies and stream flows.
To provide for adequate maintenance of all permanent stormwater structures in the Municipality.
To ensure effective long-term operation and maintenance of all permanent stormwater management facilities.
To address certain requirements of the Municipal Separate Storm Sewer System (MS4) National Pollution Discharge Elimination System (NPDES) Phase II Stormwater Regulations.
The following activities are included within the scope of this chapter:
The following table provides information on how development will need to control the stormwater runoff produced by the proposed work:
Neither the granting of any approval under the stormwater management provisions of this chapter nor the compliance with the provisions of this chapter or with any condition imposed by a municipal official hereunder shall relieve the developer, his agents, servants or employees, their heirs, successors or assigns from any responsibility for damage to persons or property resulting therefrom, or as otherwise imposed by law, nor impose any liability upon the Municipality for damages to persons or property.
The granting of a permit which includes any stormwater management facilities shall not constitute a representation, guaranty or warranty of any kind by the Municipality, or by an official or employee thereof, of the practicability or safety of any structure, use or other plan proposed and shall create no liability upon or cause of action against such public body, official or employee for any damage that may result pursuant thereto.
As used in this chapter, the following terms shall have the meanings indicated:
- ACCELERATED EROSION
- The removal of the surface of the land through the combined action of man's activity and the natural processes of a rate greater than would occur because of the natural process alone.
- The Storm Water Management Act (Act of October 4, 1978, P.L. 864, No. 167; 32 P.S. §§ 680.1 through 680.17, as amended by Act of May 24, 1984, No. 63).
- AGRICULTURAL ACTIVITIES
- The work of producing crops or raising livestock, including tillage, plowing, disking, harrowing, pasturing and installation of conservation measures. Construction of new buildings or impervious area is not considered an agricultural activity.
- As applied to land, a change in topography as a result of the moving of soil and rock from one location or position to another; also, the changing of surface conditions by causing the surface to be more or less impervious; land disturbance.
- A landowner or developer who has filed an application for development, including his/her heirs, successors and assigns.
- BIORETENTION AREA/RAIN GARDEN
- A bioretention area/rain garden is a planted depression that collects rainwater runoff from impervious areas, like roofs, driveways, walkways, parking lots, and compacted lawn areas. The bioretention area/rain garden must have a soil mix that is capable of allowing rainwater to infiltrate. This reduces rain runoff by allowing stormwater to soak into the ground. Plantings for the bioretention area/rain garden must be native plants and must be designed by a licensed landscape architect. The purpose of a bioretention area/rain garden is to improve water quality in nearby bodies of water.
- BMPs (BEST MANAGEMENT PRACTICES)
- Activities, facilities, designs, measures or procedures used to manage stormwater impacts from regulated earth disturbance activities, to meet state water quality requirements, to promote groundwater recharge and to otherwise meet the purposes of this chapter. BMPs include but are not limited to infiltration, filter strips, low-impact design, bioretention, wet ponds, permeable paving, grassed swales, forested buffers, sand filters and detention basins.
- A perceptible natural or artificial waterway which periodically or continuously contains moving water or which forms a connecting link between two bodies of water. It has a definite bed and banks which confine water.
- CHANNEL EROSION
- The widening, deepening, and cutting of small channels and waterways due to erosion caused by moderate to large floods.
- An underground reservoir or tank for storing rainwater.
- CONSERVATION DISTRICT
- The Westmoreland Conservation District.
- A closed conduit for the free passage of surface drainage under a highway, railroad, canal or other embankment.
- An artificial barrier, together with its appurtenant works, constructed for the purpose of impounding or storing water or another fluid or semifluid, or a refuse bank, fill or structure for highway, railroad or other purposes which does or may impound water or another fluid or semifluid.
- DESIGN CRITERIA
- The engineering guidelines, specified and referred to in this chapter, which are used in the design and construction of stormwater management facilities; objectives, results or limits which must be met by a facility, structure or process in performance of its intended functions.
- DESIGN STORM
- See "storm frequency."
- The slowing, dampening or attenuating of stormwater runoff flows entering the natural drainage pattern or storm drainage system by temporarily holding the water in man-made facilities.
- DETENTION BASIN (POND)
- A pond, impoundment or reservoir used to temporarily store and retard stormwater runoff.
- DETENTION BASIN FOREBAY
- A forebay is a small pool located near the inlet of a detention basin or other stormwater management facility. These devices are designed as initial storage areas to trap and settle out sediment and heavy pollutants before they reach the main basin. Installing an earth berm, gabion wall, or other barrier near the inlet to cause stormwater to pool temporarily can form the pool area. Forebays act as a pretreatment feature on a stormwater pond and can greatly reduce the overall pond maintenance requirements. The minimum forebay volume shall be equal to 25% of the two-year, twenty-four-hour storm volume.
- The person, persons or any corporation, partnership, association or other entity or any responsible person therein or agent therefor that undertakes the activities associated with changes in land use. The term "developer" is intended to include but not necessarily be limited to the terms "subdivider," "owner" and "builder," even though the individuals involved in successive stages of a project may vary.
- Any activity, construction, alteration, change in land use or practice that affects stormwater runoff characteristics.
- DEVELOPMENT SITE
- The specific tract of land for which a regulated earth disturbance activity is proposed.
- The release of stormwater from a project site, drainage basin or other point of interest; the rate and volume of flow of stormwater, such as in a stream or pipe, generally expressed in cubic feet per second.
- A channel or berm constructed to a predetermined grade across a slope and designed to collect and/or divert runoff from slopes which are subject to erosion.
- DOWNSLOPE PROPERTY LINE
- That portion of the property line of the lot, tract, or parcels of land being developed located such that all overland or pipe flow from the site would be directed towards it.
- DRAINAGE AREA
- The area of a drainage basin or watershed, expressed in acres, square miles or other unit of area; also called "catchment area" or "watershed"; the area served by a sewer system receiving stormwater and surface water or by a watercourse.
- DRAINAGE CONVEYANCE FACILITY
- A stormwater management facility designed to transport stormwater runoff, and includes streams, channels, swales, pipes, conduits, culverts, storm sewers, etc.
- DRAINAGE EASEMENT
- A right, granted by a landowner to a grantee, allowing the use of private land for stormwater management purposes.
- EARTH DISTURBANCE ACTIVITY
- A construction or other activity which disturbs the surface of the land, including but not limited to clearing and grubbing, grading, excavations, embankments, road maintenance, building construction and the moving, depositing, stockpiling, or storing of soil, rock, or earth material.
- Any structure or activity which in any manner changes, expands or diminishes the course, current or cross section of any watercourse, floodway or body of water.
- Any reference to the "Engineer" will mean the duly appointed representative of the Municipality of Murrysville.
- The wearing away of the lands by running water, winds and waves.
- EROSION AND SEDIMENT POLLUTION CONTROL PLAN
- A plan that is designed to minimize accelerated erosion and sedimentation through the use of BMPs.
- EROSION CONTROL
- The application of measures to reduce erosion of land surfaces.
- EXISTING CONDITIONS
- The initial condition of a project site prior to the proposed construction. If the initial condition of the site is undeveloped land, the land use shall be considered in good condition.
- A general but temporary condition of partial or complete inundation of normally dry land areas from the overflow of streams, rivers, and other waters of the commonwealth.
- Any land area susceptible to inundation by water from any natural source or delineated by applicable Department of Housing and Urban Development, Federal Insurance Administration, Flood Hazard Boundary Maps, as being a special flood hazard area; also included are areas that comprise Group 13 soils, as listed in Appendix A of the Pennsylvania Department of Environmental Protection (PADEP) Technical Manual for Sewage Enforcement Officers (as amended or replaced from time to time by PADEP).
- FLOODPLAIN RESTORATION
- Floodplain restoration is the use of bioengineering practices, removal of fill material, restructuring of stream channels and/or the restoration or management of riparian corridors in order to create a floodplain to compensate for the past loss of floodplains.
- The channel of the watercourse and those portions of the adjoining floodplains that are reasonably required to carry and discharge the one-hundred-year-frequency 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 one-hundred-year-frequency 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.
- FOREST RESTORATION
- Forest restoration is the planting of trees in areas that have become devoid of original forest cover. The new tree plantings must be native species of trees. New trees must be a minimum height of four feet for evergreen trees and six feet for deciduous trees. Forest restoration plans must be prepared by a professional forester who is a member of the Society of American Foresters or the Association of Consulting Foresters. A professional forester is a person who has a B.S. or higher degree in forestry from a four-year school of forestry accredited by the Society of American Foresters.
- A vertical distance between the elevation of the design high water and the top of a dam, levee, tank, basin, or diversion ridge. The space is required as a safety margin in a pond or basin.
- GRASSED WATERWAY
- A natural or constructed waterway, usually broad and shallow, covered with erosion-resistant grasses, used to conduct surface water from cropland.
- GREEN ROOF
- A green roof is a conventional roof that is covered with a layer of vegetation. Also known as "living roofs," green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating a habitat for wildlife, and helping to lower urban air temperatures and combat the heat island effect. There are two types of green roofs: intensive roofs, which are thicker and can support a wider variety of plants but are heavier and require more maintenance, and extensive roofs, which are covered in a light layer of vegetation and are lighter than an intensive green roof.
- GROUND COVER
- Materials covering the ground surface.
- Subsurface water occupying the saturation zone, from which wells and springs are fed, as well as the base flows for natural streams.
- GROUNDWATER RECHARGE
- Replenishment of groundwater naturally by precipitation or by artificial means.
- HYDRAULIC GRADE LINE
- A line joining points whose vertical distance from the center of the cross section of the fluid flowing in a pipe is proportional to the pressure of the pipe at the point.
- IMPERVIOUS SURFACE
- A surface that prevents the easy percolation and infiltration of water into the ground. "Impervious surfaces" include but are not limited to roof areas, parking areas, driveway areas, streets and sidewalks. Any surface areas designed to initially be gravel or crushed stone shall be assumed to be impervious surfaces unless they are designed to be permanent BMPs.
- A retention or detention basin designed to retain stormwater runoff and release it at a controlled rate.
- The flow or movement of water through the interstices or pores of a soil or other porous medium; the absorption of stormwater by the soil.
- INFILTRATION STRUCTURE
- A structure designed to direct runoff into the ground (e.g., french drains, seepage pits, seepage trench).
- A surface structure designed to allow for the inflow of stormwater flows; the upstream end of any structure through which water may flow.
- LAND DEVELOPMENT
- Any of the following activities:
- A. The improvement of one lot or two or more contiguous lots, tracts or parcels of land for any purpose involving:
- (1) A group of two or more residential or nonresidential buildings, whether proposed initially or cumulatively, or a single nonresidential building on a lot or lots regardless of the number of occupants or tenure; or
- (2) The division or allocation of land or space, whether initially or cumulatively, between or among two or more existing or prospective occupants by means of or for the purpose of streets, common areas, leaseholds, condominiums, building groups or other features.
- B. A subdivision of land.
- LAND DISTURBANCE
- Any activity involving the changing, grading, transportation, fill and any other activity which causes land to be altered.
- MS4 PERMIT
- The permit issued by the PADEP to the Municipality to ensure compliance with the Pennsylvania Municipal Separate Storm Sewer System Program.
- The Municipality of Murrysville.
- NATURAL STORMWATER RUNOFF REGIME
- A watershed where natural surface configurations, runoff characteristics and defined drainage conveyances have attained the conditions of equilibrium.
- NONPOINT SOURCE POLLUTION
- Pollution that enters a water body from diffuse origins in the watershed and does not result from discernible, confined, or discrete conveyances.
- NPDES (NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM) PERMIT
- A permit issued by the PADEP for earth disturbance activities.
- The Natural Resources Conservation Service (previously SCS).
- OFF-SITE STORMWATER
- Those stormwater flows that are generated on property that is not part of the land being developed.
- OPEN CHANNEL
- A drainage element in which stormwater flows with an open surface. Open channels include but shall not be limited to natural and man-made drainageways, swales, streams, ditches, canals, and pipes flowing partly full.
- The point, location or structure where drainage discharges from a sewer, drain or other conduit.
- OUTLET CONTROL STRUCTURE
- The device used to control and meter the discharge from a detention facility, placed at the outlet or downstream end of any structure through which water may flow.
- The Pennsylvania Department of Environmental Protection.
- PARKING LOT STORAGE
- The use of impervious parking areas as temporary impoundments with controlled release rates during rainstorms.
- PEAK DISCHARGE
- The maximum rate of flow of water at a given point and time resulting from a specified storm event.
- PERVIOUS (POROUS) PAVEMENT
- Pervious (porous) pavement is a special type of pavement with a high porosity that allows water from precipitation and other sources to pass directly through, thereby reducing the runoff from a site and allowing groundwater recharge. Pervious pavement can be concrete, brick pavers and other types of material that allow for infiltration.
- PLANNING COMMISSION
- The Planning Commission of the Municipality of Murrysville.
- POINT SOURCE
- Any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, or conduit from which stormwater is or may be discharged.
- PRIVATE ENTITY
- A partnership, corporation, homeowners' association, condominium association or any other similar associations, as distinguished from an individual lot owner.
- PROJECT SITE
- The specific area of land where any regulated earth disturbance activities in the Municipality are planned, conducted, or maintained.
- RATIONAL FORMULA
- A rainfall-runoff relation used to estimate peak flow, expressed by the following formula:
- RECURRENCE INTERVAL
- The average interval of time, stated in years, within which a given storm event will be equaled or exceeded once.
- 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. The redevelopment will result in a reduction in impervious area.
- REGIONAL STORMWATER DETENTION FACILITY
- A stormwater facility that controls runoff from more than one development site used by developers when it is more cost effective than providing a stormwater management facility for each development separately.
- RELEASE RATE PERCENTAGE
- The percentage of predevelopment peak rate of runoff from a watershed subarea which defines the allowable post-development peak discharge from any development site in that subarea. This release rate applies uniformly to all land development or alterations within the subarea. A delineation of the release rate percentages by subarea is shown on the Municipal Stormwater Management District Map.
- RETENTION BASIN (POND)
- 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, over which an event of a given magnitude can be expected to recur.
- A vertical pipe extending from the bottom of a pond that is used to control the discharge rate from the pond for a specified design storm.
- ROOFTOP DETENTION
- Temporary ponding and gradual release of stormwater falling directly onto flat roof surfaces by incorporating controlled-flow roof drains into building designs.
- See "stormwater runoff."
- RUNOFF CHARACTERISTICS
- The surface components of any watershed which affect the rate, amount and direction of stormwater runoff. These may include, but not be limited to, vegetation, soils, slopes and man-made landscape alterations.
- The United States Department of Agriculture, Soil Conservation Service; now known as the Natural Resources Conservation Service (NRCS).
- Mineral or organic solid material that is being transported or has been moved from its original site by air, water or ice and has come to rest.
- SEDIMENT BASIN
- A barrier, dam, retention or detention basin located and designed to retain rock, sand, gravel, silt, or other material transported by water.
- SEDIMENT POLLUTION
- The placement, discharge or any other introduction of sediment into the waters of the commonwealth occurring from the failure to design, construct, implement or maintain control measures and control facilities in accordance with the requirements of this chapter.
- SEEPAGE PIT/SEEPAGE TRENCH
- An area of excavated earth filled with loose stone or similar coarse material, into which surface water is directed for infiltration into the ground.
- SEEPAGE TANK
- A subsurface concrete tank surrounded by stone, into which surface water is directed for infiltration into the ground.
- SEPARATE STORM SEWER SYSTEM
- A conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels or storm drains) primarily used for collecting and conveying stormwater runoff.
- SHEET FLOW
- Stormwater runoff that flows over the ground surface as a thin, even layer, not concentrated in a channel.
- SOIL COVER COMPLEX METHOD
- A method of runoff computation developed by the NRCS that is based on relating soil type and land use/cover to a runoff parameter called "curve number (CN)."
- SOIL GROUP, HYDROLOGIC
- A classification of soils by the NRCS into four runoff potential groups. The groups range from A soils, which are very permeable and produce little runoff, to D soils, which are not very permeable and produce much more runoff.
- A depression in the embankment of a pond or basin which is used to pass peak discharges greater than the maximum design storm controlled by the pond.
- STATE WATER QUALITY REQUIREMENTS
- As defined under state regulations, protection of designated and existing uses (see 25 Pa. Code Chapters 93 and 96).
- STORAGE FACILITY
- See "detention basin (pond)" or "retention basin (pond)."
- STORM FREQUENCY
- 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.
- STORM SEWER (DRAIN)
- A pipe that carries stormwater runoff, street water and other drainage but excludes domestic sewage and industrial waste.
- STORMWATER COLLECTION SYSTEM
- Natural or man-made structures that collect and transport stormwater through or from a drainage area to the point of final outlet, including but not limited to any of the following: conduits and appurtenant features, canals, channels, ditches, streams, culverts, streets and pumping stations.
- STORMWATER MANAGEMENT FACILITY
- Any structure, device or other natural or man-made infrastructure so designed and/or constructed to control, convey, store, retain, detain, manage, mitigate or otherwise affect stormwater runoff.
- STORMWATER MANAGEMENT FACILITY OPERATIONS AND MAINTENANCE PLAN
- The plan prepared by the developer or his representative indicating how the operation and maintenance of stormwater management facilities will be managed by the appropriate party.
- STORMWATER REUSE
- Entails storing stormwater runoff and then using it as a source of irrigation water or other nonpotable use. The philosophy behind the practice is that the lowest-quality water should be used for the lowest-quality need.
- STORMWATER RUNOFF
- The flow of water over and/or in water bodies that results from and occurs during and immediately following a rainfall event.
- STREAM RESTORATION
- Stream restoration is the use of bioengineering practices, native material revetments, channel stability structures and/or the restoration or management of riparian corridors in order to protect upland BMPs, restore the natural function of the stream corridor and improve water quality by reducing sedimentation to streams from stream bank erosion.
- The smallest drainage unit of a watershed for which stormwater management criteria have been established in the Turtle Creek Stormwater Management Plan.
- A specific area contributing runoff to a predefined point. The areas are further defined as shown on the Municipal Stormwater Management District Map.
- The division or redivision of a lot, tract, or parcel of land by any means into two or more lots, tracts, parcels or other divisions of land, including changes in existing lot lines for the purpose, whether immediate or future, of lease, transfer of ownership, or building or lot development; provided, however, that the subdivision by lease of land for agricultural purposes into parcels of more than 10 acres, not including any new street or easement of access or any residential dwelling, shall be exempted.
- A low-lying stretch of land which gathers or carries surface water runoff.
- TIME OF CONCENTRATION (Tc)
- The time for surface runoff to travel from the hydraulically most distant point of the watershed to a point of interest within the watershed. This time is the combined total of overland flow time and flow time in pipes or channels, if any.
- TURTLE CREEK STORMWATER MANAGEMENT PLAN
- A watershed-wide plan developed by Allegheny and Westmoreland Counties for the Turtle Creek watershed to identify stormwater management problems and corrective actions and to establish hydrologic and hydraulic modeling requirements for existing and future stormwater management methods and facilities.
- WATER QUALITY INLETS
- Any inlet designed to provide for the removal of debris and pollutants. The applicant must provide detailed evidence of the water quality improvements that will be achieved with the proposed water quality inlet.
- WATER QUALITY VOLUME
- A calculated volume of stormwater runoff from impervious or semi-impervious areas which is required to be captured and mitigated through various BMPs. This may be achieved through the use of structural or nonstructural BMPs. Numerically, the water quality volume is a product of the volumetric runoff coefficient, site area and depth of rainfall (usually one inch or two inches).
- Any channel for conveyance of surface water, having a defined bed and banks, whether natural or artificial, with perennial or intermittent flow.
- WATERS OF THE COMMONWEALTH
- Rivers, streams, creeks, rivulets, 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 the commonwealth.
- The entire region or area drained by a river or other body of water, whether natural or artificial.
- WET POND
- See "retention basin."
- WETLAND/WETLAND RESTORATION
- Those areas that are inundated or saturated by surface water or groundwater at 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, including swamps, marshes, bogs, fens, and similar areas. Wetland restoration is the process of creating a wetland to compensate for those wetlands that have been lost or destroyed.
- Those areas that are inundated or saturated by surface water or groundwater at 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, including swamps, marshes, bogs, fens, and similar areas.
The location and boundaries of the watersheds and subareas are shown on the Municipal Stormwater Management District Map hereby adopted as part of this section.
The following provisions shall be considered the overriding performance standards against which all proposed stormwater control measures shall be evaluated and shall apply throughout the Municipality of Murrysville:
Any landowner and any person engaged in the alteration or development of land which may affect stormwater runoff characteristics shall implement such measures as are reasonably necessary to prevent injury to health, safety or other property. Such measures shall include such actions as are required:
To assure that the maximum rate of stormwater runoff is no greater after development than prior to development activities;
To manage the quantity, velocity and direction of resulting stormwater runoff in a manner which otherwise adequately protects health and property from possible injury;
To meet any and all requirements of the NPDES permit;
To meet any and all requirements of the MS4 permit; and
To provide stormwater BMPs to control the volume of stormwater being generated by the development. The stormwater BMPs are an integral part of the stormwater management plan.
The stormwater management plan for the development site must consider all the stormwater runoff generated on the development site and all stormwater runoff flowing over the site.
No discharge of toxic materials (i.e., materials that would be in violation of the Pennsylvania Clean Streams Law) shall be permitted into any stormwater management system.
A minimum of 50% of all parking spaces associated with any development or redevelopment must be constructed of pervious pavement. This requirement is not applicable to a single-family residence or for parking areas with fewer than four spaces. All parking must meet the requirements of Murrysville Code Chapter 220, Article VII, Parking Regulations.
Watershed standards: Turtle Creek Stormwater Management District.
The stormwater performance standards contained in this section are intended to implement the standards and criteria contained in the Turtle Creek Stormwater Management Plan, adopted and approved in accordance with the Pennsylvania Storm Water Management Act. If there is any discrepancy between the provisions of this section and the standards and criteria of the plan, or if the watershed plan is subsequently amended, then the standards/criteria of the current watershed plan shall govern.
Storm frequencies. Stormwater management facilities on all development sites shall control the peak stormwater discharge for the two-, ten-, twenty-five- and one-hundred-year storm frequencies. The SCS twenty-four-hour, Type II rainfall distribution shall be used for analyzing stormwater runoff for both pre- and post-development conditions. The twenty-four-hour total rainfalls for these storm frequencies in the watershed are:
Development sites. For purpose of computing peak flow rates and runoff hydrographs from development sites, calculations shall be performed using one of the following SCS publications: Technical Release (TR) 55 or 20, HEC I, or Pennsylvania State Runoff Model. For sites less than five acres, the Rational Method can be used as approved by the Engineer. The intensity for the Rational Formula will be as defined in the PennDOT Drainage Manual for this region. All final flow numbers developed by the hydrology methods above will be rounded to the nearest whole number.
Stormwater collection/conveyance facilities. For the purposes of designing storm sewers, open swales and other stormwater runoff collection and conveyance facilities, any of the above-listed calculation methods or the Rational Method may be used. Rainfall intensities for design should be obtained from the PennDOT Drainage Manual.
Predevelopment conditions. Predevelopment conditions shall be assumed to be those which existed on any site at the time of adoption of the Turtle Creek Stormwater Management Plan. Hydrologic conditions for all areas with pervious cover (i.e., fields, woods, lawn areas, pastures, cropland, etc.) shall be assumed to be in good condition, and the lowest recommended SCS runoff curve number (CN) shall be applied for all pervious land uses within the respective range for each land use and hydrologic soil group.
Routing of hydrographs through the detention/retention facilities for the purpose of designing those facilities shall be accomplished using the Modified-Puls Method or recognized reservoir routing method, subject to the approval of the Municipality and county.
Off-site stormwater that naturally flows through the developed site shall not be permitted to flow through the proposed stormwater management facilities as can reasonably be expected. When it is not possible to direct the off-site stormwater away from the proposed facility, the total off-site stormwater permitted to flow through any one facility shall be limited to 10% of the total flow discharging to the facility. This restriction shall not apply to wet ponds.
Release rate percentage.
Procedures for use shall be as follows:
Identify the specific subarea in which the development site is located and obtain the subarea release rate percentage from the watershed map.
Compute the pre- and post-development runoff hydrographs for each stormwater outfall on the development site using an acceptable calculation method for the two-, ten-, twenty-five- and one-hundred-year storms. Apply no on-site detention for stormwater management, but include any techniques to minimize impervious surfaces and/or increase the time of concentration for stormwater flowing from the development site. If the post-development peak runoff rate and volume are less than or equal to the predevelopment peak runoff rate and volume, then additional stormwater control shall not be required at that outfall. If the post-development peak runoff rate and volume are greater than the predevelopment peak runoff rate and volume, then stormwater detention will be required, and the capacity of the detention facility must be calculated in the manner prescribed below.
Multiply the subarea release rate percentage by the predevelopment rate of runoff from the development site to determine the maximum allowable release rate from any detention facility for the four designated storm events.
Design the outlet control facility and size the volume of the detention facility using the calculated post-development hydrograph and accepted hydrograph routing procedures in consideration of the maximum allowable release rate.
Watershed standards: Pucketa Creek Stormwater Management District. The standards for the Pucketa Creek watershed shall be identical to those in the Turtle Creek watershed, with the exception that all release rates will be 100%.
Applicants may select runoff control techniques or a combination of techniques which is most suitable to control stormwater runoff from the development site. All controls must be subject to approval of the Municipal Engineer. The Municipal Engineer may request specific information on design and/or operating features of the proposed stormwater controls in order to determine their suitability and adequacy to meet the standards of this chapter.
The stormwater collection system must be designed to carry all storm flows generated by storm events up to and including the ten-year storm event. For storm events greater than the ten-year storm, the maximum capacity of the collection system must be analyzed. All stormwater that cannot be carried by the collection system must be analyzed as overland flow. The overland flows should, as much as possible, be directed to the stormwater detention facilities. All flows generated by storms greater than the ten-year flows must be analyzed to ensure that proper detention is attained and that minimal damage to persons or property is incurred by these flows.
The applicant should consider the effects of the proposed stormwater management techniques on any special soil conditions or geological hazards which may exist on the development site. In the event that such conditions are identified on the site, the Municipal Engineer may require in-depth studies by a competent geotechnical engineer. Not all stormwater control methods may be advisable or allowable at a particular development site.
Infiltration practices shall be used to the extent practicable to reduce volume increases and promote groundwater recharge. A combination of successive practices may be used to achieve the applicable minimum control requirements.
Design calculations must be provided for all stormwater facilities, including detention ponds, BMPs, ditches, swales, inlets, pipes, culverts, etc.
All BMPs must be shown on the recorded plan.
Required BMPs (for all developments not qualifying for water quality volume retention).
A minimum of 80% of the ten-year, twenty-four-hour storm runoff volume must be treated by stormwater BMPs. All stormwater management plans must include a minimum of two of the following BMPs with the plan:
Other BMPs may be used as approved by the Municipal Engineer.
Water quality volume retention.
Water quality volume retention will be the calculated volume of stormwater runoff from impervious or semi-impervious areas which is required to be captured and mitigated through various BMPs.
This may be achieved through the use of structural or nonstructural BMPs.
The water quality volume is the difference in stormwater runoff volume between the pre-development conditions and the post-development conditions as calculated for the two-year storm event. In the calculations for the pre-development conditions, 20% of the existing impervious area must be considered meadow in good condition.
All impervious areas must drain to a stormwater BMP.
Criteria for post-collection infiltration systems.
Infiltration systems shall be sized and designed based upon local soil and groundwater conditions.
Infiltration systems shall be greater than three feet deep and shall be located at least 10 feet from basement walls.
Infiltration systems shall not be used to handle runoff that may contain industrial or chemical runoff.
Infiltration systems shall be protected from any runoff that may contaminate the proposed system.
The stormwater infiltration facility design shall provide an overflow system with measures to provide a non erosive velocity of flow along its entire length and at the outfall.
A four-inch-diameter perforated underdrain must be provided for all infiltration systems. This underdrain must sit on top of a minimum of six inches of free-draining stone.
Criteria for stormwater detention facilities.
If detention facilities are utilized for the development site, the facility(s) shall be designed such that post-development peak runoff rates from the developed site are controlled to those rates defined by the subarea release rate percentage for the two-, ten-, twenty-five- and one-hundred-year storm frequencies.
All detention facilities shall be equipped with outlet structures to provide discharge control for the four designated storm frequencies. Provisions shall also be made to safely pass, at minimum, the post-development one-hundred-year storm runoff without breaching or otherwise damaging (i.e., impairing the continued function of) the facilities.
Shared-storage facilities, which provide detention of runoff for more than one development site within a single subarea, may be considered and are encouraged. Such facilities shall meet the criteria contained in this section. In addition, runoff from the development sites involved shall be conveyed to the facility in a manner that avoids adverse impacts (such as flooding or erosion) to channels and properties located between the development site and the shared-storage facilities.
Where detention facilities will be utilized, multiple-use facilities, such as wetlands, lakes, ballfields or similar recreation/open space uses, are encouraged wherever feasible, subject to the approval of the Municipality, the Westmoreland Conservation District and the Pennsylvania Department of Environmental Protection.
Design criteria for wet ponds.
Wet ponds shall be constructed on hydric or wet soils which have an infiltration rate of less than 0.2 inch per hour.
A minimum drainage area of five acres shall be directed to the pond unless a source of recharge is utilized, such as a natural spring or well.
The length of the pond between the inflow and outlet points shall be maximized. In addition, an irregular shoreline shall be provided. These factors will help to provide the greatest possible water quality benefit.
A means of dewatering the wet pond must be provided with the design.
A shallow forebay shall be provided adjacent to all inflow areas. The forebay shall be planted with emergent wetland vegetation. The forebay serves to enhance sediment trapping and pollutant removal.
All wet ponds shall be designed with public safety as a primary concern. All wet ponds shall have maximum slope grade of 3:1 (three feet horizontal to one foot vertical) on all slopes.
Wet ponds shall have a deep-water zone to encourage gravity settling of suspended fines.
A minimum freeboard of two feet must be provided above the one-hundred-year storm event flow through the emergency spillway.
Emergency spillway. The emergency spillway shall consist of an open channel constructed adjacent to the embankment over undisturbed material (not fill).
A planting plan shall be developed for the wet pond, showing all proposed aquatic, emergent and upland plantings.
The landscaping requirements for wet ponds shall be the same as required for dry ponds, as a minimum.
All discharge-control structures, discharge pipes, access drives and emergency spillway requirements must meet the criteria listed below for dry basins.
A structural, permanent energy dissipator must be provided at all discharge points from wet ponds.
Design criteria for dry basins.
Spillway design. The outlets for any detention facility must be capable of passing the one-hundred-year storm flows. All facilities must have an emergency spillway capable of handling the one-hundred-year storm flows.
Principal spillway (outlet structure). The principal spillway (main outlet structure) must be constructed with reinforced concrete. All principal spillway openings larger than three square feet must be covered with an open grating to prevent unauthorized access. All outlet structures must have only one low flow orifice. This low flow orifice must be no larger than a four-inch diameter or 0.09 square feet. The next orifice(s) above the low orifice must be higher than the water surface elevation of the two-year, twenty-four-hour storm as routed through the low flow orifice. All orifices installed in the outlet structure must be premanufactured with neat, clean lines. No field cutting of orifices will be accepted.
Discharge pipe. The discharge pipe for the detention facility must be constructed of reinforced concrete and be provided with an O-ring in the bell-and-spigot connection. This pipe must be anchored in a concrete cradle that runs the entire length from the outlet structure to the downstream endwall. No antiseep collars will be permitted. The pipe will terminate with a concrete endwall.
Principal spillway base. The base of the principal spillway must be firmly anchored to prevent floating. If the riser of the spillway is greater than 10 feet in height, computations must be submitted to the Engineer for approval. A factor of safety of 1.5 will be applied to these computations.
Freeboard. The minimum allowable freeboard between the top of the calculated high-water mark in the emergency spillway and the top of the embankment shall be one foot.
Emergency spillway. The emergency spillway shall consist of an open channel constructed adjacent to the embankment over undisturbed material (not fill).
Underdrain. All detention facilities shall be designed and constructed with underdrain (minimum size four-inch diameter) to ensure the proper draining of the facility.
Fences. All detention facilities that do not meet the minimum slope criteria set forth in this chapter shall be fenced. All fences associated with a detention facility will fully encompass the facility and be a chain-link-type fence with a minimum height of six feet. All fence posts must be firmly anchored with concrete. The bottom of the fence must follow the ground contours. A double-swing gate with a minimum width of 12 feet must be provided with the fence to permit ingress and egress to the access road.
Access. All detention facilities must have an access road with a minimum width of 12 feet and a slope not to exceed 20% to the bottom of the pond.
A structural, permanent energy dissipator must be provided at all discharge points from wet ponds.
Embankment. All embankments must be keyed into the original ground. A minimum of 25% of the interior slopes must not exceed a ratio of 3:1 horizontal to vertical dimensions. The remainder of the interior slopes must not exceed a ratio of 2:1 horizontal to vertical dimensions. The following top widths shall be used for all detention basin embankments:
Other considerations which should be incorporated into the design of the detention facilities include:
Inflow and outflow structures shall be designed and installed to prevent erosion, and bottoms of impoundment-type structures should be protected from soil erosion.
Control and removal of debris, both in the storage structure and in all inlet or outlet devices, shall be a design consideration.
A nonerodible low-flow channel shall be provided where deemed necessary by the Municipal Engineer.
Inflow and outflow structures, pumping stations and other structures shall be designed and protected to minimize safety hazards.
Landscaping shall be provided for the facility which harmonizes with the surrounding area. The developer will be responsible for planting trees and plants around the basin area with the purpose of creating a natural looking site. The type and species of vegetation to be planted must be of a type that is compatible with the soil and proposed environment. No planting of trees will be permitted on the embankment slopes. The embankment slopes will be planted with shrubs and ground cover. A minimum of one large deciduous tree must be planted for each 50 linear feet of perimeter, as measured along the top contour of the basin. A minimum of four shrubs must be planted for each tree planted. All trees and plantings must conform to the requirements as set forth in the Murrysville Code, Chapter 220, Zoning, § 220-51, Landscaping and buffering.
The facility shall be located to facilitate maintenance, considering the frequency and type of equipment that will be required.
The design of all stormwater facilities must be prepared with maintenance as a prime concern. Stormwater facilities on individual lots must be designed to ensure that these facilities will not be altered in the future. The use of landscaping buffers should be considered in these designs.
All stormwater facilities located on individual lots must be provided with a stormwater easement.
Criteria for underground systems.
Drainage easements must be provided for all underground stormwater management facilities (where necessary).
Underground stormwater management facilities will be situated a minimum of 200 feet from any active water well.
Underground stormwater management facilities will be situated a minimum distance of 100 feet from any active on-lot septic system.
Underground stormwater management facilities will be situated a minimum distance of 50 feet from any property line.
Underground detention vaults and tanks must meet structural requirements for overburden support and traffic loading, if appropriate.
Detention vaults. A minimum 3,000 psi structural reinforced concrete may be used for underground detention vaults. All construction joints must be provided with water stops. Cast-in-place wall sections must be designed as retaining walls. The maximum depth from finished grade to the vault invert will be 15 feet.
Detention pipes. The minimum pipe diameter for underground detention is 24 inches.
Emergency spillway. Every underground detention facility must be designed and constructed to pass the one-hundred-year unmetered storm flows in the event the outlet structure should become blocked or nonfunctioning.
Access. Every underground detention facility must have a minimum of two access points for maintenance. Steps or ladders must be provided for human access.
Vents. Any underground detention facility that is large enough to accommodate human occupancy for maintenance must have vents at the high points of every pipe or structure.
The finished grade above any underground detention facility must have a slope not exceeding 3%.
All inflow to an underground detention facility must be filtered through a trash and debris collection device. Maintenance criteria must be established for cleaning of these devices.
Criteria for redevelopment.
When a development qualifies as a redevelopment project, the existing stormwater facilities (if any) may be used, provided that they meet the requirements of this chapter.
If the existing stormwater facilities are in place, a report detailing the condition of the infrastructure to be used is required. This report must be signed and sealed by a professional engineer licensed in Pennsylvania.
The developer shall make all necessary repairs or modifications to the existing facilities as detailed in the engineer's report.
Criteria for collection/conveyance facilities.
All stormwater runoff collection or conveyance facilities, whether storm sewers or other open or closed channels, shall be designed in accordance with the following basic standards:
All sites shall be graded to provide drainage away from and around the structure in order to prevent any potential flooding damage.
Roof drains shall be directed to the nearest BMP. If no BMPs are available, the developer must connect the roof drains to an approved collection system for conveyance to a detention facility or natural drainage course. No roof drain shall be permitted to discharge onto any road surface.
Collection/conveyance facilities shall not be installed parallel and close to the top or bottom of a major embankment to avoid the possibility of failing or causing the embankment to fail.
All collection/conveyance facilities shall be designed to convey the ten-year-storm peak flow rate from the contributing drainage area and to carry it to the nearest suitable outlet, such as a stormwater control facility, storm sewer or natural watercourse.
Where drainage swales or open channels are used, they shall be suitably lined to prevent erosion and designed to avoid excessive velocities.
Any inlet designed to retain water must have a minimum depth of five feet to the invert of the discharge pipe. The purpose of this depth is to insure that the breeding of insects cannot occur in the standing water.
Wherever storm sewers are proposed to be utilized, they shall comply with the Municipal Road and Street Design and Construction Standards.
An erosion/sedimentation plan shall be provided in accordance with the Pennsylvania Erosion/Sedimentation Regulations (25 Pa. Code Chapter 102) and the standards and guidelines of the Westmoreland County Conservation District.
Proposed erosion/sedimentation measures shall be submitted with the stormwater management plan as part of the preliminary and final application.
Evidence of any necessary permit(s) for regulated earth disturbance activities from the appropriate DEP regional office or County Conservation District must be provided to the Municipality. The issuance of an NPDES construction permit (or permit coverage under the statewide general permit [PAG-2]) shall satisfy the requirement of Subsection A.
A copy of the erosion and sediment control plan and any required permit(s), as required by DEP regulations, shall be available at the project site at all times.
The erosion and sedimentation control plan must specify biodegradable material as approved by the Municipality and the Westmoreland Conservation District. These materials must be specified and installed in accordance with the manufacturer's recommendations.
The stormwater management plan for the development site shall contain an operation and maintenance plan prepared by the developer and approved by the Municipal Engineer. The operation and maintenance plan shall outline required routine maintenance actions and schedules necessary to ensure proper operation of the facility(s).
The stormwater management plan for the development site shall establish responsibilities for the continuing operation and maintenance of all proposed stormwater control facilities, consistent with the following principles:
If a development consists of structures or lots which are to be separately owned and in which streets, sewers and other public improvements are to be dedicated to the Municipality, stormwater control facilities shall also be dedicated to and maintained by the Municipality. All stormwater control facilities, including detention facilities and accessways, must be on a separate parcel(s) dedicated by deed to the Municipality. Dedication and acceptance thereof shall be at the sole election of the Municipality.
If a development site is to be maintained in a single ownership or if sewers and other public improvements are to be privately owned and maintained, then the ownership and maintenance of stormwater control facilities shall be the responsibility of the owner or private management entity.
The Council of the Municipality of Murrysville, with recommendations from the engineer, shall make the final determination on the continuing maintenance responsibilities prior to final approval of the stormwater management plan. The Council reserves the right to accept the ownership and operating responsibility for any or all of the stormwater management controls.
When and where the Municipality may accept the dedication of stormwater management facilities, the developer of the subdivision, land development or planned residential development shall provide fees to the Municipality for the future maintenance of said facilities. This fee shall be posted in the Municipality's Stormwater Maintenance Fund prior to the acceptance of said facilities by the Murrysville Council. The fee shall be determined as follows:
Necessary inspections, typically annually for the first four years and every other year thereafter.
Periodic maintenance required, to include labor and equipment cost.
The developer shall provide the Municipality with an estimated cost for a ten-year period from the date of acceptance by the Municipality.
This estimated cost shall be a present worth value based on a reasonable-rate-of-return inflation factor.
The Municipal Engineer shall approve the developer's estimates.
Acceptance criteria. The following criteria must be met before the Municipality of Murrysville's Council will consider the subject of any stormwater management facility acceptance:
The facility(s) must be located in a plan or development that was approved by the Murrysville Council and includes language in the approval of the plan or development that said facility(s) are to be considered for acceptance by the Municipality.
The Municipality will only consider acceptance of stormwater management facilities that are located on a separate parcel(s) of real estate that will be dedicated to the Municipality. This separate parcel(s) of land must have frontage on a public road, and access to the parcel(s) must be from this public road. Stormwater management facilities located in easements will not be accepted by the Municipality.
All required improvements in the development, or approved phase of a development, have been constructed, inspected and approved by the Murrysville Engineering Department.
The stormwater management facility(s) must be complete and are functioning as designed and detailed in the final approved plan.
All required documentation, including as-built drawings signed and sealed by a professional surveyor licensed in Pennsylvania, and bonding have been delivered and approved by the municipal staff.
There are no unresolved or outstanding issues with any federal, state or local agencies. This includes the release of any NPDES permit issued for the development.
The streets in the approved development where the stormwater management facility(s) are located must have been accepted by the Municipality.
All storm pipes must be flushed with clean water and all inlets cleaned free of debris before acceptance by the Municipality.
The Municipality will not accept any stormwater management facility that contains any operable device (i.e., pumps, aerators, etc.).
Maintenance agreement for privately owned stormwater facilities.
Prior to final approval of the site's stormwater management plan, the property owner shall sign and record, in the Westmoreland County Recorder of Deeds office, a maintenance agreement covering all stormwater control facilities which are to be privately owned. The agreement shall stipulate that:
The owner shall operate and maintain all facilities in accordance with the approved operation and maintenance schedule and shall keep all facilities in a safe and attractive manner.
The owner shall convey to the Municipality easements and/or rights-of-way to assure access for periodic inspections by the Municipality and maintenance if required.
The owner shall keep on file with the Municipality the name, address and telephone number of the person or company responsible for maintenance activities; in the event of change, new information will be submitted to the Municipality within 10 days of the change.
If the owner fails to maintain the stormwater control facilities, the Municipality is hereby authorized and directed to give notice, by personal service or by United States mail, to the owner, by certified mail, to correct the problem(s) or to otherwise conform to the requirements of the operations and maintenance plan within 30 days after issuance of such notice.
In case the owner shall neglect, fail or refuse to comply with such notice within the period of time stated therein, the Municipality may perform the necessary maintenance work or corrective action, and the owner shall reimburse the Municipality for all costs, including reasonable attorney's fees, together with any additional payment authorized by law, which may be collected by the Municipality from such owner in the manner provided by law for the collection of municipal claims or by an action of assumpsit, and said sum shall be a legal and/or equitable lien or charge upon the subject land and facilities from the date of completion of said work.
Other items may be included in the agreement where determined necessary to guarantee the satisfactory maintenance of all facilities. The maintenance agreement shall be subject to the review and approval of the Municipal Solicitor and Council.
General requirements. No final subdivision/land development plan shall be approved, no permit authorizing construction issued or any earthmoving or land disturbance activity initiated until the final stormwater management plan for the development is approved in accordance with the provisions of this chapter.
Stormwater plan contents. The stormwater management plan shall consist of all applicable calculations, maps and plans. A note on the maps shall refer to the associated computations and erosion and sedimentation control plan by title and date. The cover sheet of the computations and erosion and sedimentation control plan shall refer to the associate maps by title and date. All stormwater management plan materials shall be submitted to the Municipality in a format that is clear, concise, legible, neat and well organized; otherwise, the stormwater management plan shall be disapproved and returned to the applicant.
A feasibility analysis that evaluates the potential application of infiltration, flow attenuation, wet pond, bioretention or wetland BMPs must be submitted with the stormwater management plans.
General format. The stormwater plan shall be drawn to a scale of not less than one inch equals 200 feet. All sheets shall contain a title block with the name and address of the applicant and engineer; scale; North arrow; legend; and date of preparation.
Stormwater report narrative. The stormwater management report must contain a narrative with the following information as a minimum requirement:
Description of pre-development conditions.
Description of post-development conditions.
Stormwater control methodologies.
Detailed description of stormwater BMPs and devices.
Summary table of pre- and post-development flows, detention storage volumes, detention discharge rates and water surface elevations.
Existing and proposed features. The plan shall show the following:
Watershed location. The plan shall provide a Key Map showing the location of the development site within the watershed(s) and watershed subarea(s) and shall, on all site drawings, show the boundaries of the watershed(s) and subarea(s) as they are located on the development site and identify watershed name(s) and subarea number(s).
Floodplain boundaries. The plan shall identify one-hundred-year floodplains on the development site (as appropriate) based on the Municipal Flood Insurance Study Maps.
Natural features. The plan shall show all bodies of water (natural or artificial), watercourses (permanent and intermittent), swales, wetlands and other natural drainage courses on the development site or which will be affected by runoff from the development.
Soils. The plan shall provide an overlay showing all soil types and boundaries within the development site (consult the Westmoreland County Soil Survey).
Contours. The plan shall show existing and final contours at intervals of two feet; in areas with slopes greater than 20%, ten-foot contour intervals may be used.
Land cover. The plan shall show existing and final land cover classifications as necessary to support and illustrate the runoff calculations performed.
Drainage area delineations. The plan shall show the boundaries of the drainage areas employed in the runoff calculations performed.
Stormwater management controls. The plan shall show any existing stormwater management or drainage controls and/or structures, such as sanitary and storm sewers, swales, culverts, etc., which are located on the development site or which are located off site but will be affected by runoff from the development.
Professional certification. The stormwater management plan (including all calculations) must be prepared and sealed by a registered professional engineer, surveyor or landscape architect with training and expertise in hydrology and hydraulics. Documentation of qualifications may be required by the Municipality.
Runoff calculations. Calculations for determining pre- and post-development discharge rates and for designing proposed stormwater control facilities must be submitted with the stormwater management plan. All calculations shall be prepared using the methods and data prescribed by § 198-5 of this chapter.
Stormwater controls. All proposed stormwater runoff control measures must be shown on the plan, including methods for collecting, conveying and storing stormwater runoff on site, which are to be used both during and after construction. Erosion and sedimentation controls shall be shown in accordance with applicable municipal and County Conservation District requirements. The plan shall provide information on the exact type, location, sizing, design and construction of all proposed facilities and the relationship to the existing watershed drainage system.
If the development is to be constructed in stages, the applicant must demonstrate that stormwater facilities will be installed to manage stormwater runoff safely during each stage of development.
A schedule for the installation of all temporary and permanent stormwater control measures and devices shall be submitted.
Easements, rights-of-way, deed restrictions. All existing and proposed easements and rights-of-way for drainage and/or access to 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.
Other permits/approvals. A list of any approvals/permits relative to stormwater management that will be required from other governmental agencies (including DEP Chapter 105 permits) and anticipated dates of submissions/receipt should be included with the stormwater plan submission. Copies of permit applications may be requested by the Municipality where they may be helpful for the plan review.
Maintenance program. The application shall contain a proposed maintenance plan for all stormwater control facilities in accordance with the following:
Identify the proposed ownership entity (e.g., Municipality, property owner, private corporation, homeowners' association or other entity).
Include a maintenance program for all facilities, outlining the type of maintenance activities, probable frequencies, personnel and equipment requirements and estimated annual maintenance costs.
Identify method of financing continuing operation and maintenance if the facility is to be owned by other than the Municipality.
Submit any legal agreements required to implement the maintenance program and copies of the maintenance agreement as required by this chapter.
To control post-construction stormwater impacts from regulated earth disturbance activities, state water quality requirements can be met by BMPs which shall be proposed by the developer at the time of application for approval. The developer shall propose post-construction BMPs and a plan for assurance of long-term operations and maintenance of those BMPs at the time of application.
The best management practices (BMPs) must be designed to protect and maintain existing uses (e.g., drinking water use, cold-water fishery use) and maintain the level of water quality necessary to protect those uses in all streams, and to protect and maintain water quality in special-protection streams, as required by statewide regulations at 25 Pa. Code Chapter 93 (collectively referred to herein as "state water quality requirements").
Financial guaranties. The developer shall post securities with the Municipality of Murrysville to secure the completion of all required improvements in accordance with the provisions of this chapter, and the amount and administration shall be in accordance with Section 509 of the Pennsylvania Municipalities Planning Code. Release of these securities will be in accordance with the Pennsylvania Municipalities Planning Code upon completion of the required work and submittal of the as-built drawings sealed by a registered surveyor or engineer certifying that the completed work has conformed to the approved plan. The as-built drawings must include the location and size of all BMPs. If there is a discrepancy between the as-built size of the detention facilities and the planned size, the developer shall have his engineer resubmit the stormwater management plan and report for approval by the Municipal Engineer. There will be no bond release until the as-built drawings and any subsequent submittals have been approved.
Editor's Note: See 53 P.S. § 10509.
Before submitting the stormwater plan, applicants are urged to consult with the Municipality and County Conservation District on the requirements for safely managing the development site in a manner consistent with the municipal ordinances and applicable watershed stormwater management plan. These agencies may also be helpful in providing necessary data for the stormwater management plan.
Applicants are encouraged to submit a sketch plan with a narrative description of the proposed stormwater management controls for general guidance and discussion with the Municipality.
The preapplication phase is not mandatory; any review comments provided by the Municipality or other agencies are advisory only and do not constitute any legally binding action on the part of the Municipality.
Stormwater plan reviews.
Submission of plans. Stormwater plan applications shall be submitted with the preliminary and final subdivision/land development applications.
Review by Municipal Engineer and County Conservation District. Stormwater plans shall be reviewed by the Municipal Engineer and the County Conservation District. At its discretion, the Municipality and/or county may also engage other specialists in hydrology or hydraulics to assist with the stormwater plan review. All fees for additional reviews will be paid for by the applicant. The Conservation District will review the plan for general compliance with the watershed plan standards and criteria and watershed-wide impacts and, where appropriate, may consult with adjacent counties for their comments. If the Conservation District's review identifies the improper application of the watershed standards and criteria or the possibility of harmful impacts downstream from the development site's proposed stormwater management system, the applicant and Municipal Engineer will be notified so that the necessary modifications can be made to promote safe stormwater management.
Municipal Engineer's review. The Municipal Engineer shall approve or disapprove the stormwater management plan based on the requirements of this chapter, the standards and criteria of the watershed plan and good engineering practices. The Engineer shall submit a written report, along with supporting documentation, stating the reason(s) for approval or disapproval.
Status of Engineer's determination. The approval/disapproval of the site's stormwater management plan by the Municipal Engineer shall be considered final. The applicant may request Council to override the Engineer's decision.
Permits required from other government agencies. Where the proposed development requires an obstruction permit from the Pennsylvania DEP or an erosion/sedimentation permit from the County Conservation District, then final stormwater management plan approval shall be conditional upon receipt of such permits. However, no building permit shall be issued, nor construction started, until the permits are received and copies filed with the Municipality.
Upon final stormwater plan approval and receipt of all necessary permits, the applicant must obtain a land operations permit from the Municipality. With the issuance of a land operations permit, the applicant may commence to install or implement the approved stormwater management controls.
If site development or building construction does not begin within two years of the date of final approval of the stormwater management plan, then before doing so, the applicant shall resubmit the stormwater management plan to verify that no condition has changed within the watershed that would affect the feasibility or effectiveness of the previously approved stormwater management controls. Further, if for any reason development activities are suspended for two years or more, then the same requirement for resubmission of the stormwater management plan shall apply.
If the request for a plan modification is initiated before construction begins, the stormwater plan must be resubmitted and reviewed according to the procedures contained in § 198-10 above.
If the request for a plan modification is initiated after construction is under way, the Municipal Engineer shall have the authority to approve or disapprove the modification based on field inspection, provided that:
The requested changes in stormwater controls do not result in any modifications to other approved municipal land use/development requirements (e.g., building setbacks, yards, etc.); and
The performance standards in § 198-5 are met. Notification of the Engineer's action shall be sent to the Council, which may issue a stay of the plan modification at the next regularly scheduled meeting and require the permittee to resubmit the plan modification for full stormwater plan review in accordance with § 198-9 above.
The Municipal Engineer or a designated representative shall inspect the construction of the temporary and permanent stormwater management system for the development site. The permittee shall notify the Engineer 48 hours in advance of the start and completion of key development phases, such as:
Preliminary site preparation, including the stripping of vegetation, the stockpiling of topsoil and construction of temporary stormwater management and erosion control facilities.
Rough grading, permanent drainage construction and other site improvements and any permanent ground cover.
Construction of all permanent stormwater control facilities.
Final grading and site stabilization.
No work shall commence on any subsequent phase until the preceding one has been inspected and approved. If there are deficiencies in any phase, the Municipal Engineer shall issue a written description of the required corrections and stipulate the time by which they must be made.
If, during construction, the contractor or permittee identifies any site condition, such as subsurface soil conditions or alterations in surface or subsurface drainage, which could affect the feasibility of the approved stormwater facilities, he/she shall notify the Municipal Engineer within 24 hours of the discovery of such conditions and request a field inspection. The Municipal Engineer shall determine if the condition requires a stormwater plan modification.
In cases where stormwater facilities are to be installed in areas of landslide-prone soils or other special site conditions exist, the Municipality may require special precautions, such as soil testing and core borings, full-time inspectors and/or similar measures. All costs of any such measures shall be borne by the permittee.
No person, corporation or other entity shall allow, or cause to allow, stormwater discharges into the Municipality's separate storm sewer system which are not composed entirely of stormwater except as provided in Subsection B below or discharges allowed under a state or federal permit.
Discharges which may be allowed are as follows:
Discharges from firefighting activities.
Potable water sources, including dechlorinated waterline and fire hydrant flushings.
Routine external building washdown which does not use detergents or other compounds.
Water from crawl space pumps.
Water from individual residential car washing.
Uncontaminated water from foundations or from footing drains.
Flows from riparian habitats and wetlands.
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.
If at any time the Municipality determines that the discharges identified above significantly contribute to pollution of waters of the commonwealth, or is so notified by DEP, the Municipality reserves the right to issue an order to cease the offending discharge, and the discharger will have a reasonable time to cease the offending discharge.
Nothing in this section shall affect a discharger's responsibilities under state law.
The following connections are prohibited, except as provided in § 198-14 above:
Any drain or conveyance, whether on the surface or subsurface, which allows any nonstormwater discharge, including sewage, process wastewater, and wash water, to enter the separate storm sewer system and any connections to the storm drain system from indoor drains and sinks.
Any drain or conveyance connected from a commercial or industrial land use to the separate storm sewer system which has not been documented in plans, maps, or equivalent records and approved by the Municipality.
No person shall modify, remove, fill, landscape or alter any existing stormwater BMP, unless it is part of an approved maintenance program, without the written approval of the Municipality.
No person shall place any structure, fill, landscaping or vegetation into a stormwater BMP or within a drainage easement, which would limit or alter the functioning of the BMP, without the written approval of the Municipality.
Right of entry. Upon presentation of proper credentials, duly authorized representatives of the Municipality may enter at reasonable times upon any property to investigate or ascertain the condition of the subject property in regard to any aspect regulated by this chapter.
Notification. In the event that the applicant, developer, owner or his/her agent fails to comply with the requirements of this chapter or fails to conform to the requirements of any permit, a written notice of violation shall be issued. Such notification shall set forth the nature of the violations and establish a time limit for correction of the violations. Upon failure to comply within the time specified, unless otherwise extended by the Municipality, the applicant, developer, owner or his/her agent shall be subject to the enforcement remedies of this chapter.
In addition to other remedies, the Municipality may institute and maintain appropriate actions by law or in equity to restrain, correct or abate a violation, to prevent unlawful construction, to recover damages and to prevent illegal occupancy of a building or premises.
Any person who has violated or knowingly permitted the violation of the provisions of this chapter shall, upon being found liable therefor in a civil enforcement proceeding commenced by the Municipality, pay a fine of not less than $100 and not more than $500, plus court costs, including reasonable attorneys' fees, incurred by the Municipality. No judgment shall commence or be imposed, levied or payable until the date of the determination of a violation by the District Justice.
If the defendant neither pays nor timely appeals the judgment, the Municipality may enforce the judgment pursuant to applicable rules of civil procedure.
Each day that a violation continues shall constitute a separate violation, unless the District Justice further determines that there was a good faith basis for the person violating the chapter to have believed that there was no such violation. In such case, there shall be deemed to have been only one such violation until the fifth day following the date of the District Justice's determination of a violation; thereafter, each day that a violation continues shall constitute a separate violation.
All judgments, costs and reasonable attorneys' fees collected for the violation of this chapter shall be paid over to the Municipality.
The Court of Common Pleas, upon petition, may grant an order of stay, upon cause shown, tolling the per diem fine pending a final adjudication of the violation and judgment.
Nothing contained in this section shall be construed or interpreted to grant to any person or entity other than the Municipality the right to commence any action for enforcement pursuant to this section.
Additional remedies. In addition to the above remedies, the Municipality may also seek remedies and penalties under applicable Pennsylvania statutes, or regulations adopted pursuant thereto, including but not limited to the Storm Water Management Act (32 P.S. §§ 680.1 through 680.17), the Dam Safety and Encroachments Act (32 P.S. §§ 693.1 through 693.27) and the Erosion and Sediment Control Regulations (Chapter 102 of Title 25 of the Pennsylvania Code). Any activity conducted in violation of this chapter or any Pennsylvania-approved watershed stormwater management plan may be declared a public nuisance by the Municipality and abatable as such.