Township of New Hanover, PA DEFINITIONS

[Ord. 07-07, 7/23/2007, § 202; as amended by Ord. No. 22-08, 12/1/2022]

As used in this chapter, the following terms shall have the meanings indicated:

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.

AGRICULTURAL ACTIVITIES

The work of producing crops and raising livestock, including tillage, plowing, disking, harrowing, pasturing, mushroom growing, nursery and sod operations, and installation of conservation measures. Construction of new buildings or impervious area is not considered an agricultural activity.

ALTERATION

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.

APPLICANT

A person who has filed an application for approval to engage in any regulated activity defined in § 23-105 of this chapter.

AS-BUILT DRAWINGS

Engineering or site drawings maintained by the contractor as he constructs the project and upon which he documents the actual locations of the building components and changes to the original contract documents. These documents, or a copy of same, are turned over to the Municipal Engineer at the completion of the project.

BANKFULL

The channel at the top-of-bank or point from where water begins to overflow onto a floodplain.

BASE FLOW

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

BIORETENTION

A stormwater retention area that utilizes woody and herbaceous plants and soils to remove pollutants before infiltration occurs.

BMP (BEST MANAGEMENT PRACTICE)

Activities, facilities, designs, measures, or procedures used to manage stormwater impacts from regulated activities, to provide water quality treatment, infiltration, volume reduction, and/or peak rate control, 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 "nonstructural." In this chapter, nonstructural BMPs or measures include certain low impact development and conservation design practices used to minimize the contact of pollutants with stormwater runoff. These practices aim to limit the total volume of stormwater runoff and manage stormwater at its source by techniques such as protecting natural systems and incorporating existing landscape features. Nonstructural BMPs include, but are not limited to, the protection of sensitive and special value features such as wetlands and riparian areas, the preservation of open space while clustering and concentrating development, the reduction of impervious cover, and the disconnection of rooftops from storm sewers. Structural BMPs are those that consist of a physical system that is designed and engineered 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, bioretention, wet ponds, permeable paving, grassed swales, riparian buffers, sand filters, detention basins, tree plantings, soil amendments, and manufactured devices. Structural and nonstructural stormwater BMPs are permanent appurtenances to the site. (See also "stormwater management facility" and "stormwater control measure.")

CHANNEL

An open drainage feature through which stormwater flows. Channels include, but shall not be limited to, natural and man-made drainageways, swales, streams, ditches, canals, and pipes flowing partly full.

CHANNEL EROSION

The widening, deepening, or headward cutting of channels and waterways caused by stormwater runoff or bankfull flows.

CISTERN

An underground reservoir or tank for storing rainwater.

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 Chapter 102. In this chapter, "Conservation District" refers to the Montgomery County Conservation District.

CONVEYANCE

A natural or man-made existing or proposed stormwater management facility, feature or channel used for the transportation or transmission of stormwater from one place to another. For the purposes of this chapter, "conveyance" shall include pipes, drainage ditches, channels, and swales (vegetated and other), gutters, stream channels, and like facilities or features.

CULVERT

A structure with its appurtenant works that carries water under or through an embankment or fill.

DAM

A man-made barrier, together with its appurtenant works, constructed for the purpose of impounding or storing water or another fluid or semifluid. A dam may include a refuse bank, fill, or structure for highway, railroad, or other purposes which impounds or may impound water or another fluid or semifluid.

DEP

The Pennsylvania Department of Environmental Protection. Also referred to as "PA DEP" or "PADEP."

DESIGN PROFESSIONAL (QUALIFIED)

A Pennsylvania registered professional engineer, registered landscape architect, or registered professional land surveyor trained to develop stormwater management plans.

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.

DESIGNEE

The agent of the Montgomery County Planning Commission, Montgomery County Conservation District, and/or agent of the Board of Supervisors involved with the administration, review, or enforcement of any provisions of this chapter by contract or memorandum of understanding.

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 soon after a rainfall event and become dry until the next rainfall event.

DETENTION VOLUME

The volume of runoff that is captured and released into the waters of the commonwealth at a controlled rate.

DEVELOPER

A person, company, or organization who seeks to undertake any regulated earth disturbance activities at a project site in New Hanover Township.

DEVELOPMENT

Any human-induced change to improved or unimproved real estate, whether public or private, including, but not limited to, land development, construction, installation, or expansion of a building or other structure, land division, street construction, drilling, and site alteration such as embankments, dredging, grubbing, grading, paving, parking or storage facilities, excavation, filling, stockpiling, or clearing. As used in this chapter, "development" encompasses both new development and redevelopment.

DEVELOPMENT SITE

The specific tract or parcel of land where any regulated activity set forth in § 23-105 is planned, conducted, or maintained.

DIAMETER AT BREAST HEIGHT (dbh)

The outside bark diameter at breast height which is defined as 4 1/2 feet (1.37m) above the forest floor on the uphill side of the tree.

DIFFUSED DRAINAGE DISCHARGE

Drainage discharge that is not confined to a single point location or channel, including sheet flow or shallow concentrated flow.

DISCHARGE

(verb) To release water from a project, site, aquifer, drainage basin, or other point of interest;

(noun) The rate and volume of flow of water such as in a stream, generally expressed in cubic feet per second (see "peak discharge").

DISCHARGE POINT

The point of discharge for a stormwater facility.

DISTURBED AREAS

Unstabilized land area where an earth disturbance activity is occurring or has occurred.

DITCH

A man-made waterway constructed for irrigation or stormwater conveyance purposes.

DOWNSLOPE PROPERTY LINE

That portion of the property line of the lot, tract, or parcels of land being developed, located such that overland or pipe flow from the project site would be directed towards it by gravity.

EARTH DISTURBANCE ACTIVITY

A construction or other human activity which disturbs the surface of land, including, but not limited to, clearing and grubbing, grading, excavations, embankments, land development, agricultural plowing or tilling, timber harvesting activities, road maintenance activities, mineral extraction, and the moving, depositing, stockpiling, or storing of soil, rock, or earth materials.

EASEMENT

A right granted by a landowner to a grantee allowing the use of private land for stormwater management purposes.

EMERGENCY SPILLWAY

A conveyance area that is used to pass peak discharge greater than the maximum design storm controlled by the stormwater facility.

ENCROACHMENT

A structure or activity that changes, expands, or diminishes the course, current, or cross section of a watercourse, floodway, or body of water.

EROSION

The process by which the surface of the land, including water/stream channels, is worn away by water, wind, or chemical action.

EROSION AND SEDIMENT CONTROL PLAN

A plan that is designed to minimize accelerated erosion and sedimentation. Said plan must be submitted to and approved by the appropriate Conservation District before construction can begin.

EVAPOTRANSPIRATION (ET)

The combined processes of evaporation from the water or soil surface and transpiration of water by plants.

EXCEPTIONAL VALUE WATERS

Surface waters of high quality that satisfy Pennsylvania Code Title 25, Environmental Protection, Chapter 93, Water Quality Standards, § 93.4b(b) (relating to antidegradation).

EXISTING CONDITIONS

The dominant land cover during the five-year period immediately preceding a proposed regulated activity. If the existing condition of the site is undeveloped land, the land use shall be considered as "meadow" unless the natural land cover is proven to generate a lower curve number or Rational "c" value, such as forested lands.

FEMA

Federal Emergency Management Agency.

FLOOD

A temporary condition of partial or complete inundation of land areas from the overflow of streams, rivers, and other waters of this commonwealth.

FLOODPLAIN

A relatively flat or low land area which is subject to partial or complete inundation from an adjoining or nearby stream, river, or watercourse; and/or area subject to the unusual and rapid accumulation of surface waters from any source.

FLOODWAY

The channel of a watercourse and those portions of the adjoining floodplains that are reasonably required to carry and discharge the 100-year-frequency flood (also called the "base flood" or "1% annual chance 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 floodway, it is assumed, absent evidence to the contrary, that the floodway extends from the stream to 50 feet from the top-of-bank.

FLUVIAL GEOMORPHOLOGY

The study of landforms associated with river channels and the processes that form them.

FOREST MANAGEMENT/TIMBER OPERATIONS

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

FREEBOARD

A vertical distance between the elevation of the design high water and the top of a dam, levee, tank, basin, swale, or diversion berm. The space is required as a safety margin in a pond or basin.

GARDENING

The activity of working in a garden, growing and cultivating plants as part of horticulture, including the production of flowers, fruits, nuts, vegetables, and herbs for personal consumption.

GRADE

(noun) A slope, usually of a road, channel, or natural ground specified in percent and shown on plans as specified herein.

(verb) To finish the surface of a roadbed, the top of an embankment, or the bottom of an excavation.

GRASSED WATERWAY

A natural or man-made waterway, usually broad and shallow, covered with erosion-resistant grasses used to convey surface water.

GREEN INFRASTRUCTURE

Systems and practices that use or mimic natural processes to infiltrate, evapotranspire, or reuse stormwater on the site where it is generated.

GROUNDWATER

Water beneath the earth's surface that supplies wells and springs and is often between saturated soil and rock.

GROUNDWATER RECHARGE

The replenishment of existing natural underground water supplies from rain or overland flow.

HIGH QUALITY WATERS

Surface waters having quality which exceeds levels necessary to support propagation of fish, shellfish, and wildlife and recreation in and on the water by satisfying Pennsylvania Code Title 25, Environmental Protection, Chapter 93, Water Quality Standards, § 93.4b(a).

HIGH TUNNEL

A structure which meets the following:

Is used for the production, processing, keeping, storing, sale or shelter of an agricultural commodity as defined in Section 2 of the Act of December 19, 1974 (P.L. 973, No. 319), known as the "Pennsylvania Farmland and Forest Land Assessment Act of 1974," as amended,[1] or for the storage of agricultural equipment or supplies; and

Is constructed with all the following:

(1)

Has a metal, wood, or plastic frame;

(2)

When covered, has a plastic, woven textile, or other flexible covering; and

(3)

Has a floor made of soil, crushed stone, matting, pavers, or a floating concrete slab.

HOTSPOTS

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

HYDROGRAPH

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

HYDROLOGIC REGIME

The hydrologic cycle or balance that sustains quality and quantity of stormwater, base flow, storage, and groundwater supplies under natural conditions.

HYDROLOGIC SOIL GROUP

A classification of soils by the Natural Resources Conservation Service (NRCS), formerly the Soil Conservation Service (SCS), 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.

IMPERVIOUS SURFACE

A surface that prevents the infiltration of water into the ground. Impervious surfaces include, but are not limited to, streets, sidewalks, pavements, driveway areas, parking lots, patios, roofs, buildings, storage sheds, swimming pools and any compacted gravel or crushed stone. Areas of decks, permeable pavement, eco-pavers, artificial turf or other impervious materials that are designed to allow infiltration as part of the surface installation are considered impervious surfaces, and appropriate stormwater BMPs must be designed to offset the increased runoff volume created by the surface material.

IMPOUNDMENT

A retention or detention basin designed to retain stormwater runoff and release it at a controlled rate.

INFILL

Development that occurs on smaller parcels that remain undeveloped but are within or in very close proximity to urban or densely developed areas. Infill development usually relies on existing infrastructure and does not require an extension of water, sewer, or other public utilities.

INFILTRATION

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

INFILTRATION STRUCTURES

A structure designed to direct runoff into the underground water (e.g., french drains, seepage pits, or seepage trenches).

INFLOW

The flow entering the stormwater management facility and/or BMP.

INLET

The upstream end of any structure through which water may flow.

INTERMITTENT STREAM

A stream that flows only part of the time. Flow generally occurs for several weeks or months in response to seasonal precipitation or groundwater discharge.

INVERT

The lowest surface; the floor or bottom of a culvert, drain, sewer, channel, basin, BMP, or orifice.

LAND DEVELOPMENT

Any of the following activities:

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.

(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.

A subdivision of land.

Development in accordance with Section 503(1.1) of the Pennsylvania Municipalities Planning Code, 53 P.S. § 10503(1.1).

LIMITING ZONE

A soil horizon or condition in the soil profile or underlying strata that includes one of the following:

A seasonal high-water table, whether perched or regional, determined by direct observation of the water table or indicated by soil mottling.

A rock with open joints, fracture or solution channels, or masses of loose rock fragments, including gravel, with insufficient fine soil to fill the voids between the fragments.

A rock formation, other stratum, or soil condition that is so slowly permeable that it effectively limits downward passage of water.

LOT

A designated parcel, tract, or area of land established by a plat or otherwise as permitted by law and to be used, developed, or built upon as a unit.

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, provide evapotranspiration 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.

MAIN STEM (MAIN CHANNEL)

Any stream segment or other runoff conveyance used as a reach in watershed-specific hydrologic models.

MANAGED RELEASE CONCEPT (MRC)

A postconstruction stormwater management (PCSM) strategy that comprises the collection, management, and filtration of captured runoff from the contributing drainage area through a best management practice (BMP) that is preferably vegetated and includes release of a portion of the captured runoff through an underdrain within the BMP. If the MRC BMP is not vegetated, then pretreatment is required to meet water quality requirements. MRC is intended to be used for project areas or subareas where infiltration is considered infeasible to meet regulatory requirements. Refer to the current "Managed Release Concept" guidance document from DEP.

MANNING EQUATION (MANNING FORMULA)

A method for calculation of velocity of flow (e.g., feet per second) and flow rate (e.g., cubic feet per second) in open channels based upon channel shape, roughness, depth of flow, and slope. "Open channels" may include closed conduits so long as the flow is not under pressure.

MAXIMUM DESIGN STORM

The maximum (largest) design storm that is controlled by the stormwater facility.

MUNICIPAL ENGINEER

A professional engineer licensed as such in the Commonwealth of Pennsylvania, duly appointed as the engineer for New Hanover Township, planning agency, or joint planning commission.

MUNICIPALITY

New Hanover Township, Montgomery County, Pennsylvania.

NATURAL CONDITION

Predevelopment condition.

NATURAL HYDROLOGIC REGIME

See "hydrologic regime."

NATURAL RECHARGE AREA

Undisturbed surface area or depression where stormwater collects and a portion of which infiltrates and replenishes the underground and groundwater.

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.

NONSTORMWATER DISCHARGES

Water flowing in stormwater collection facilities, such as pipes or swales, which is not the result of a rainfall event or snowmelt.

NONSTRUCTURAL BEST MANAGEMENT PRACTICES (BMPs)

Methods of controlling stormwater runoff quantity and quality, such as innovative site planning, impervious area and grading reduction, protection of natural depression areas, temporary ponding on site, and other techniques.

NPDES

National Pollutant Discharge Elimination System, the federal government's system for issuance of permits under the Clean Water Act, which is delegated to DEP in Pennsylvania.

NRCS

Natural Resource Conservation Service (previously SCS).

OPEN CHANNEL

A conveyance channel that is not enclosed.

OUTFALL

"Point source" as described in 40 CFR 122.2 at the point where New Hanover Township's storm sewer system discharges to surface waters of the commonwealth.

OUTFLOW

The flow exiting the stormwater management facility and/or BMP.

OUTLET

Points of water disposal to a stream, river, lake, tidewater, or artificial drain.

PARENT TRACT

The parcel of land from which a land development or subdivision originates, determined from the date of municipal adoption of this chapter.

PARKING LOT STORAGE

Involves the use of parking areas as temporary impoundments with controlled release rates during rainstorms.

PEAK DISCHARGE

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

PENN STATE RUNOFF MODEL

The computer-based hydrologic model developed at Pennsylvania State University.

PENNSYLVANIA STORMWATER BEST MANAGEMENT PRACTICES MANUAL (PA BMP MANUAL)

Document Number 363-0300-002 (December 2006, and as subsequently amended).

PERVIOUS SURFACE

A surface material that readily allows stormwater to infiltrate or percolate into the ground. Pervious surfaces include lawns, landscape, pasture, native vegetation areas, and areas of less than 250 square feet of uncompacted gravel that is not subjected to vehicular traffic, such as garden paths, walkways, or small patio areas. For the purposes of determining compliance with this chapter, the total horizontal projection area of all ground-mounted and freestanding solar collectors, including solar photovoltaic cells, panels, and arrays, shall be considered pervious so long as the designs note that natural vegetative cover will be preserved and/or restored underneath the solar photovoltaic cells, panels, and arrays, and the area disturbed is planned as a vegetated pervious surface.

PIPE

A culvert, closed conduit, or similar structure (including appurtenances) that conveys stormwater.

PLANNING COMMISSION

The Planning Commission of New Hanover Township.

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, as defined in state regulations at 25 Pa. Code § 92a.2.

POST-CONSTRUCTION

Period after construction during which disturbed areas are stabilized, stormwater BMPs and conveyances are in place and functioning, and all proposed improvements in the approved land development plan are completed.

PRECONSTRUCTION

Prior to commencing construction activities.

PREDEVELOPMENT CONDITION

Undeveloped/natural condition.

PRETREATMENT

Techniques employed in stormwater BMPs to provide storage or filtering to trap coarse materials and other pollutants before they enter the system, but not necessarily designed to meet the water quality volume requirements of § 23-406.

PROJECT SITE

The specific area of land where any regulated activities in New Hanover Township are planned, conducted, or maintained.

QUALIFIED PROFESSIONAL

Any person licensed by the Pennsylvania Department of State or otherwise qualified by law to perform the work required by this chapter.

RATIONAL FORMULA

A rainfall-runoff relation used to estimate peak flow.

REACH

Any stream segment or other runoff conveyance used in the watershed-specific hydrologic models.

RECHARGE

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

RECONSTRUCTION

Demolition and subsequent rebuilding of impervious surface.

RECORD DRAWINGS

Original documents revised to suit the as-built conditions and subsequently provided by the engineer to the client. The engineer reviews the contractor's as-builts against his/her own records for completeness, then either turns these over to the client or transfers the information to a set of reproducibles, in both cases for the client's permanent records.

REDEVELOPMENT

Any development that requires demolition or removal of existing structures or impervious surfaces at a site and replacement with new impervious surfaces. Maintenance activities such as top layer grinding and repaving are not considered to be redevelopment. Interior remodeling projects and tenant improvements are also not considered to be redevelopment.

REGULATED ACTIVITIES

Any earth disturbance activities or any activities that involve the alteration or development of land in a manner that may affect stormwater runoff.

REGULATED EARTH DISTURBANCE ACTIVITY

Activity involving earth disturbance subject to regulation under 25 Pa. Code Chapter 92a, 25 Pa. Code Chapter 102, or the Clean Streams Law.

REGULATED IMPERVIOUS SURFACE

Proposed impervious surface as part of a current proposed activity and all existing impervious surfaces installed after July 23, 2007, as part of previous activity.

RELEASE RATE

The percentage of existing conditions peak rate of runoff from a site or subarea to which the proposed conditions peak rate of runoff must be reduced to protect downstream areas.

REPAVING

Replacement of the impervious surface that does not involve reconstruction of an existing paved (impervious) surface.

REPLACEMENT PAVING

Reconstruction of and full replacement of an existing paved (impervious) surface.

RETENTION BASIN

A structure in which stormwater is stored and not released during the storm event. Retention basins are designed for infiltration purposes and do not have an outlet. The retention basin must infiltrate stored water in four days or less.

RETENTION VOLUME/REMOVED RUNOFF

The volume of runoff that is captured and not released directly into the surface waters of this commonwealth during or after a storm event.

RETURN PERIOD

The average interval, in years, within which a storm event of a given magnitude can be expected to recur. For example, the twenty-five-year return period rainfall would be expected to recur on the average of once every 25 years; or stated in another way, the probability of a twenty-five-year storm occurring in any one year is 0.04 (i.e., a 4% chance).

RIPARIAN BUFFER

A permanent area of trees and shrubs located adjacent to streams, lakes, and ponds, measured perpendicular to and horizontally from the top-of-bank on both sides of the stream, lake, or pond.

RISER

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.

ROAD MAINTENANCE

Earth disturbance activities within the existing road cross section, such as grading and repairing existing unpaved road surfaces, cutting road banks, cleaning or clearing drainage ditches, and other similar activities.

ROOF DRAINS

A drainage conduit or pipe that collects water runoff from a roof and leads it away from the structure.

ROOFTOP DETENTION

The temporary ponding and gradual release of stormwater falling directly onto flat roof surfaces using controlled-flow roof drains in building designs.

RUNOFF

Any part of precipitation that flows over the land surface.

SALDO

Chapter 22, Subdivision and Land Development.

SEDIMENT

Soils or other materials transported by surface water as a product of erosion.

SEDIMENT BASIN

A barrier, dam, or retention or detention basin located and designed in such a way as to retain rock, sand, gravel, silt, or other material transported by water during construction.

SEDIMENT POLLUTION

The placement, discharge, or any other introduction of sediment into the waters of the commonwealth.

SEDIMENTATION

The process by which mineral or organic matter is accumulated or deposited by the movement of water or air.

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 underground water.

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.

SHALLOW CONCENTRATED FLOW

Stormwater runoff flowing in shallow, defined ruts prior to entering a defined channel or waterway.

SHEET FLOW

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

SOIL COVER COMPLEX METHOD

A method of runoff computation developed by NRCS that is based on relating soil type and land use/cover to a runoff parameter called "curve number (CN)."

SOURCE WATER PROTECTION AREAS (SWPA)

The zone through which contaminants, if present, are likely to migrate and reach a drinking water well or surface water intake.

SPECIAL PROTECTION SUBWATERSHEDS

Watersheds that have been designated by DEP as EV or HQ waters.

SPILLWAY

A conveyance that is used to pass the peak discharge of the maximum design storm that is controlled by the stormwater facility.

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, 35 P.S. § 691.1 et seq.

STORAGE INDICATION METHOD

A reservoir routing procedure based on solution of the continuity equation (inflow minus outflow equals the change in storage) with outflow defined as a function of storage volume and depth.

STORM FREQUENCY

The number of times that a given storm event occurs or is exceeded on the average in a stated period of years (see "return period").

STORM SEWER

A system of pipes and/or open channels that conveys intercepted runoff and stormwater from other sources but excludes domestic sewage and industrial wastes.

STORMWATER

Drainage runoff from the surface of the land resulting from precipitation or snow or ice melt.

STORMWATER CONTROL MEASURE

Physical features used to effectively control, minimize, and treat stormwater runoff. [See "BMP (best management practice)"]

STORMWATER MANAGEMENT (SWM) SITE PLAN

The plan prepared by the applicant or the applicant's representative indicating how stormwater runoff will be managed at the particular site of interest according to this chapter, including all necessary design drawings, calculations, supporting text, and documentation to demonstrate that the requirements of this chapter have been met, herein referred to as "PCSM plan." All references in this chapter to "final" or "approved" PCSM plans shall incorporate the approved PCSM plan and all subsequent approved revisions thereto.

STORMWATER MANAGEMENT FACILITY

Any structure, natural or man-made, that, due to its condition, design, or construction, conveys, stores, or otherwise affects stormwater runoff quality, rate, or quantity, including best management practices and stormwater control measures. Typical stormwater management facilities include, but are not limited to, detention and retention basins, open channels, storm sewers, pipes, and infiltration structures.

STREAM

A natural watercourse.

STREAM ENCLOSURE

A bridge, culvert, or other structure in excess of 100 feet in length upstream to downstream which encloses a regulated water of the commonwealth.

SUBAREA (SUBWATERSHED)

The smallest drainage unit of a watershed for which stormwater management criteria have been established in the stormwater management plan.

SUBDIVISION

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, partition by the court for distribution to heirs or devisees, 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 involving any new street or easement of access or any residential dwelling shall be exempted.

SURFACE WATERS OF THE COMMONWEALTH

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

SWALE

A low-lying stretch of land that gathers or carries surface water runoff.

TIMBER OPERATIONS

See "forest management/timber operations."

TIME OF CONCENTRATION (Tc)

The time required 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.

TOP-OF-BANK

Highest point of elevation in a stream channel cross section at which a rising water level just begins to flow out of the channel and over the floodplain.

UNDEVELOPED CONDITION

Natural condition (see also "predevelopment condition").

USDA

United States Department of Agriculture.

VERNAL POND

Seasonal depressional wetlands that are covered by shallow water for variable periods from winter to spring but may be completely dry for most of the summer and fall.

WATERCOURSE

A channel or conveyance of surface water having a defined bed and banks, whether natural or artificial, with perennial or intermittent flow.

WATERS OF THE COMMONWEALTH

Any and all 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.

WATERSHED

Region or area drained by a river, watercourse, or other surface water of this commonwealth, whether natural or artificial.

WELLHEAD

A structure built over a well.

The source of water for a well.

WELLHEAD PROTECTION AREA

The surface and subsurface area surrounding a water supply well, well field, or spring supplying a public water system through which contaminants are reasonably likely to move toward and reach the water source.

WET POND/RETENTION BASIN

Stormwater management BMP utilizing the design and specifications set forth in the PA BMP Manual, BMP 6.6.2.

WETLAND

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 and similar areas. A wetland is an ecosystem that depends on constant or recurrent shallow inundation or saturation at or near the surface of the substrate. The minimum essential characteristics of a wetland are recurrent, sustained inundation or saturation at or near the surface and the presence of physical, chemical, and biological features reflective of recurrent, sustained inundation or saturation. Common diagnostic features of wetlands are hydrology, hydric soils and hydrophytic vegetation. Any area containing all three elements shall be defined as wetlands, as shall any area that meets the definition of a "wetland" in either 1) the United States Army Corps of Engineers Technical Report Y87-1, Corps of Engineers Wetlands Delineation Manual; or 2) the United States Environmental Protection Agency Wetlands Identification Delineation Manual, Volume I, Rational, Wetland Parameters, and Overview of Jurisdictional Approach, Volume II, Field Methodology, as most recently updated or modified; or 3) the Pennsylvania Department of Environmental Protection Wetlands Identification and Delineation, Chapter 105 Dam Safety and Waterways Management Rules and Regulations, as most recently updated or modified. Where a difference between the foregoing criteria exists, the most restrictive criteria will be used in any particular case. For the purposes of this definition and for its application to this chapter, the most restrictive criteria shall mean the criteria which effects preservation of the most extensive area of wetlands.

WOODS

A natural ground cover with more than one viable tree of a dbh of six inches or greater per 1,500 square feet which existed within three years of application; a cover condition for which SCS curve numbers have been assigned or to which equivalent Rational Method Soil Conservation Service TR-55 runoff coefficients have been assigned.

[1]

Editor's Note: See 72 P.S. § 5490.2.