For the purpose of this chapter, certain terms and words used herein shall be interpreted as follows:
A. 
Words used in the present tense include the future tense; the singular number includes the plural; and the plural number includes the singular; words of masculine gender include feminine gender; and words of feminine gender include masculine gender.
B. 
The word "includes" or "including" shall not limit the term to the specific example but is intended to extend its meaning to all other instances of like kind and character.
C. 
The word "person" includes an individual, firm, association, organization, partnership, trust, company, corporation, or any other similar entity.
D. 
The words "shall" and "must" are mandatory; the words "may" and "should" are permissive.
E. 
The words "used" or "occupied" include the words "intended, designed, maintained, or arranged to be used, occupied or maintained".
For the purposes of this chapter, these terms shall be defined as follows:
ACCELERATED EROSION
The removal of the surface of the land through the combined action of human activity and natural processes at a rate greater than would occur because of the natural process alone.
ACT
The Storm Water Management Act (Act of October 4, 1978, P.L. 864, No. 167; 32 P.S. §§ 680.1 to 680.17, as amended by Act of May 24, 1984, No. 63).
AGRICULTURAL ACTIVITIES
Activities associated with agriculture such as agricultural cultivation, agricultural operation, and animal heavy use areas. This includes the work of producing crops, tillage, land clearing, plowing, disking, harrowing, planting, harvesting crops, or pasturing and raising of livestock and installation of conservation measures. Construction of new buildings or impervious area is not considered an agricultural activity.
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; changing of surface conditions by causing the surface to be more or less impervious; land disturbance.
APPLICANT
A landowner or developer, as defined by this chapter, who has filed an application for development, including his/her heirs, successors and assigns.
BEST MANAGEMENT PRACTICES (BMPs)
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. Stormwater BMPs are commonly grouped into one of two broad categories or measures: "nonstructural" or "structural." "Nonstructural" BMPs are measures referred to as operational and/or behavior-related practices that attempt to minimize the contact of pollutants with stormwater runoff, whereas "structural" BMPs are measures that consist of a physical device or practice that is installed to capture and treat stormwater runoff. "Structural" BMPs include, but are not limited to, a wide variety of practices and devices, from large-scale retention ponds and constructed wetlands, to small-scale underground treatment systems, infiltration facilities, filter strips, low-impact design, bioretention, wet ponds, permeable paving, grassed swales, riparian or forested buffers, sand filters, detention basins, and manufactured devices. "Structural" stormwater BMPs are permanent appurtenances to the project site.
CHANNEL
A natural stream that conveys water; a ditch or open channel excavated for the flow of water.
CHANNEL EROSION
The widening, deepening, and headward cutting of small channels and waterways, due to erosion caused by moderate to large floods.
CISTERN
An underground reservoir or tank used for storing rainwater.
CONSERVATION DISTRICT
The Washington County Conservation District. The Washington County Conservation District has the authority under a delegation agreement executed with the Department of Environmental Protection to administer and enforce all or a portion of the regulations promulgated under 25 Pa. Code Chapter 102.
CULVERT
A structure with appurtenant works that carries a stream and/or stormwater runoff under or through an embankment or fill.
DAM
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.
DESIGNEE
The agent of this Peters Township and/or agent of the governing body involved with the administration, review or enforcement of any provisions of this chapter by contract or memorandum of understanding.
DESIGN STORM
The magnitude of precipitation from a storm event measured in probability of occurrence (e.g., twenty-five-year storm) and duration (e.g., twenty-four-hour), and used in computing stormwater management control systems.
DETENTION
The slowing, dampening, or attenuating of runoff flows entering the natural drainage pattern or storm drainage system by temporarily holding water on a surface area such as detention basins, reservoirs, on roof tops, in streets, parking lots, or within the drainage system itself, and releasing the water at a desired rate of discharge.
DETENTION BASIN
A facility designed to attenuate peak stormwater runoff by storing and releasing the runoff at a predetermined rate. A detention facility is designed to drain completely after a rainfall event.
DETENTION VOLUME
The volume of runoff that is captured and released into waters of the commonwealth at a controlled rate.
DEVELOPER
A person, partnership, association, corporation, or other entity, or any responsible person therein or agent thereof, that undertakes any regulated activity of this chapter.
DEVELOPMENT
Any activity, construction, alteration, change in land use or similar action that affects stormwater runoff characteristics.
DEVELOPMENT SITE
A lot, parcel or tract of land on which development is taking place or is proposed.
DISCHARGE
Rate of flow, specifically fluid flow. A volume of fluid flowing from a conduit or channel, or being released from detention storage, per unit of time. Commonly expressed as cubic feet per second (cfs), million gallons per day (mgd), gallons per minute (gpm), or cubic meters per second (cms).
DISTURBED AREA
An unstabilized land area where an earth disturbance activity is occurring or has occurred.
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 toward it.
DRAINAGE
Interception and removal of excess surface water or groundwater from land by artificial or natural means.
DRAINAGE AREA
The contributing area to a single drainage basin, expressed in acres, square miles, or other units of area; also called a catchment area, watershed, or river basin; the area served by a drainage system or by a watercourse receiving stormwater and surface water.
DRAINAGE BASIN
The area from which water is carried off by a drainage system; a watershed or catchment area.
DRAINAGE CONVEYANCE FACILITY
A stormwater management facility designed to convey stormwater runoff and shall include 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.
DRAINAGEWAY
Any natural or artificial watercourse, trench, ditch, pipe, swale, channel, or similar depression into which surface water flows.
EARTH DISTURBANCE ACTIVITY
A construction or other human activity which disturbs the surface of the land, including, but not limited to, clearing and grubbing, grading, excavations, embankments, land development, agricultural plowing and tilling, timber harvesting, road maintenance, mineral extraction, building construction and the moving, depositing, stockpiling, or storing of soil, rock or earth materials.
EROSION
The movement of soil particles by the action of water, wind, ice, or other natural forces.
EROSION AND SEDIMENT POLLUTION CONTROL PLAN
A plan which is designed to minimize accelerated erosion and sedimentation.
EXCEPTIONAL VALUE WATERS
Surface waters of high quality, which satisfies Pa. Code Title 25, Environmental Protection, Chapter 93, Water Quality Standards, § 93.4b(b) (relating to anti-degradation).
EXISTING CONDITIONS
The initial condition of a project site prior to the proposed construction. If the initial condition of the site is undeveloped land and not forested, the land use shall be considered as "meadow" unless the natural land cover is documented to generate lower curve numbers or Rational "C" Coefficient.
FEMA
The Federal Emergency Management Agency.
FLOOD
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.
FLOOD-FRINGE
The remaining portions of the one-hundred-year floodplain outside of the floodway boundary.
FLOODPLAIN
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 mapped as being a special flood hazard area. Included are lands adjoining a river or stream that have been or may be inundated by a one-hundred-year flood. 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). For regulatory purposes, the Pennsylvania Flood Plain Management Act (Act of October 4, 1978, P.L. 851, No. 166)[1] and regulations pursuant to the Act define the floodplain as the area inundated by a one-hundred-year flood and delineated on a map by FEMA (Federal Emergency Management Agency) or by the applicant in accordance with municipal ordinance requirements.
FLOODWAY
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 landward from the top of the bank of the stream.
FOREST MANAGEMENT/TIMBER OPERATIONS
Planning and activities necessary for the management of forestland. These include timber inventory and preparation of forest management plans, silvicultural treatment, cutting budgets, logging road design and construction, timber harvesting, site preparation and reforestation.
FREEBOARD
Measurement from a water surface elevation to the top of a detention/retention facility.
GRADE
A slope, usually of a road, channel or natural ground specified in percent and shown on plans as specified herein.
(TO) GRADE
To finish the surface of a roadbed, top of embankment or bottom of excavation.
GROUNDWATER RECHARGE
Replenishment of existing natural underground water supplies.
HEC-HMS MODEL CALIBRATED
(Hydrologic Engineering Center Hydrologic Modeling System) A computer-based hydrologic modeling technique adapted to the watershed(s) in Washington County for the Act 167 Plan. The model has been calibrated by adjusting key model input parameters.
HEC-1 (HYDROLOGIC ENGINEERING CENTER)
Computer model developed by the Army Corps of Engineers to predict flood hydrographs.
HIGH QUALITY WATERS
Surface water having quality, which exceeds levels necessary to support propagation of fish, shellfish, and wildlife and recreation in and on the water by satisfying Pa. Code Title 25, Environmental Protection, Chapter 93, Water Quality Standards, § 93.4b(a).
HYDRAULICS
The branch of science concerned with the mechanics of fluids, especially liquids. As applied in stormwater management, the study of the characteristics of water flow in, and conveyance capacity of, a watercourse, considering such factors as depth, velocity and turbulence.
HYDROLOGIC SOIL GROUP (HSG)
Infiltration rates of soils vary widely and are affected by subsurface permeability as well as surface intake rates. Soils are classified into one of four HSG (A, B, C, and D) according to their minimum infiltration rate, which is obtained for bare soil after prolonged wetting. The Natural Resource Conservation Service (NRCS) of the United States Department of Agriculture defines the four groups and provides a list of most of the soils in the United States and their group classification. The soils in the area of interest may be identified from a soil survey report from the local NRCS office or the County Conservation District.
HYDROLOGY
The science dealing with waters of the earth and their distribution and circulation through the atmosphere. Engineering hydrology deals with the application of hydrologic concepts to the design of projects for use and control of water.
IMPAIRED WATERWAY
Surface water segment found not attaining any one of the defined uses and is included on the Stream Integrated List represents stream assessments in an integrated format for the Clean Water Act § 303(d) listing.[2]
IMPERVIOUS SURFACE (IMPERVIOUS AREA, IMPERVIOUS MATERIAL)
A surface that prevents the infiltration of water into the ground. Impervious surface (or areas) include, but is not limited to, roofs, additional indoor living spaces, patios, garages, storage sheds and similar structures, parking or driveway areas, and any new streets and sidewalks. Any surface areas proposed to initially be gravel or crushed stone shall be assumed to be impervious surfaces.
IMPOUNDMENT
A retention or detention basin designed to retain stormwater runoff and release it at a controlled rate.
INFILTRATION STRUCTURES
A structure designed to direct runoff into the ground (e.g., french drains, seepage pits, seepage trench, etc.).
INLET
A surface connection to a closed drain. A structure at the diversion end of a conduit. The upstream end of any structure through which water may flow.
KARST
A type of topography or landscape characterized by surface depressions, sinkholes, rock pinnacles/uneven bedrock surface, steep-sided hills, underground drainage and caves. Karst is formed on carbonate rocks, such as limestone or dolomites and sometimes gypsum.
LAND DEVELOPMENT (DEVELOPMENT)
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 buildings; or
(2) 
The division or allocation of land or space 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. 
Any subdivision of land;
C. 
Development in accordance with § 503(1.1) of the Pennsylvania Municipalities Planning Code.[3]
LAND DISTURBANCE
Any activity involving grading, tilling, digging or filling or stripping of vegetation; or any other activity which causes land to be exposed to the danger of erosion or changed water flow characteristics.
LOW-IMPACT DEVELOPMENT (LID)
An approach to land development that uses various land planning and design practices and technologies to simultaneously conserve and protect natural resource systems and reduce infrastructure costs. LID still allows land to be developed, but in a cost-effective manner that helps mitigate potential environmental impacts.
MAIN STEM (MAIN CHANNEL)
Any stream segment or other runoff conveyance facility used as a reach in the Washington County Act 167 watershed hydrologic model(s).
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.
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)
The federal government's system for issuance of permits under the Clean Water Act,[4] which is delegated to PADEP in Pennsylvania.
NOAA ATLAS 14
Precipitation-Frequency Atlas of the United States, Atlas 14, Volume 2, United States Department of Commerce, National Oceanic and Atmospheric Administration, National Weather Service, Hydrometeorological Design Studies Center, Silver Spring, Maryland (2004). NOAA's Atlas 14 can be accessed at Internet address: http://hdsc.nws.noaa.gov/hdsc/pfds/
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.
NRCS
Natural Resource Conservation Service [previously Soil Conservation Service (SCS)].
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 not under pressure.
OUTFALL
A. 
Points or areas at which stormwater runoff leaves a site, which may include streams, storm sewers, swales or other well-defined natural or artificial drainage features, as well as areas of dispersed overland flows.
B. 
"Point source" as described in 40 CFR 122.2 at the point where Peters Township's storm sewer system discharges to surface waters of the commonwealth.
OUTLET
Points of water disposal from a stream, river, lake, tidewater, or artificial drain.
OUTLET STRUCTURE
A structure designed to control the volume of stormwater runoff that passes through it during a specific length of time.
PADEP
Pennsylvania Department of Environmental Protection.
PARKING LOT STORAGE
Involves the use of impervious parking areas as temporary impoundments with controlled release rates during rainstorms.
PEAK DISCHARGE
The maximum rate of stormwater runoff from a specific storm event.
PEAK RATE OF RUNOFF (OR DISCHARGE)
The maximum rate of flow of water at a given point and time resulting from a predetermined storm.
PERSON
An individual, partnership, public or private association or corporation, or a governmental unit, public utility or any other legal entity whatsoever which is recognized by law as the subject of rights and duties.
PERVIOUS AREA
Any area not defined as impervious. (See "impervious surface.")
PERVIOUS MATERIAL
Material which permits the passage or entrance of water or other liquid.
PIPE
A culvert, closed conduit, or similar structure (including appurtenances) that conveys stormwater.
PLANNING COMMISSION
The Planning Commission of Peters Township.
POINT OF INTEREST
A point of hydraulic concern such as a bridge, culvert, or channel section, for which the rate of runoff is computed or measured. Usually, located at the downstream limits of a subarea.
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 by state regulations at 25 Pa. Code § 92a.2.
PROBABLE MAXIMUM FLOOD (PMF)
The flood that may be expected from the most severe combination of critical meteorological and hydrologic conditions that is reasonably possible in any area. The PMF is derived from the probable maximum precipitation (PMP) as determined on the basis of data obtained from the National Oceanographic and Atmospheric Administration (NOAA).
PROJECT SITE
The specific area of land where any regulated activities in Peters 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.
RATE OF RUNOFF
Instantaneous measurement of water flow expressed in a unit of volume per unit of time, also referred to as "discharge." Usually stated in cubic feet per second (cfs) or gallons per minute (gpm).
RATIONAL FORMULA
A rainfall-runoff relation used to estimate peak flow.
REDEVELOPMENT
Earth disturbance activities on land, which has previously been developed.
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, Chapter 102, or the Clean Streams Law.
RELEASE RATE DISTRICT
Those subwatershed areas in which post-development flows must be reduced to a certain percentage of predevelopment flows as required to meet the plan requirements and the goals of Act 167.
RELEASE RATE PERCENTAGE (RELEASE RATE)
The percentage of predevelopment peak rate of runoff from a watershed subarea (as delineated in the watershed plan), which defines the allowable post-development peak discharge from any development site in that subarea. The release rate percentage is determined by computing the following ratio.
Subarea rate of runoff contributing to watershed peak
Subarea predevelopment peak rate of runoff
=
Release Rate Percentage
RETENTION FACILITY
A facility designed to attenuate peak stormwater runoff by retaining a portion of the runoff to create or maintain a permanent pool of water, while releasing the remaining of runoff at a predetermined rate.
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 once every 25 years; or stated in another way, the probability of a twenty-five-year storm occurring in any one given year is 0.04 (i.e., a four-percent chance).
RIPARIAN BUFFER
A vegetated area bordering perennial and intermittent streams and wetlands, that serves as a protective filter to help protect streams and wetlands from the impacts of adjacent land uses.
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 right-of-way, such as grading and repairing existing unpaved road surfaces, cutting road banks, cleaning or clearing drainage ditches, and other similar activities. Road maintenance activities that do not disturb the subbase of a paved road (such as milling and overlays) are not considered earth disturbance activities.
ROOFTOP DETENTION
Temporary ponding and gradual release of stormwater falling directly onto flat roof surfaces by incorporating controlled-flow roof drains into building designs.
RUNOFF
Any part of precipitation that flows over the land surface.
RUNOFF CAPTURE VOLUME
The volume of runoff that is captured (retained) and not released into surface waters of the commonwealth during or after a storm event.
RUNOFF CHARACTERISTICS
The surface components of any watershed which affect the rate, amount, and direction of stormwater runoff. These may include, but are not limited to, vegetation, soils, slopes, and man-made landscape alterations.
SCS
Soil Conservation Service, United States Department of Agriculture (now the NRCS).
SEDIMENT
Solid material, both mineral and organic, that is in suspension, is being transported, or has been moved from its site or origin by air, water, gravity, or ice and has come to rest on the earth's surface.
SEDIMENT BASIN
A barrier, dam, retention or detention basin located and designed to retain rock, sand, gravel, silt, or other material transported by stormwater runoff.
SEDIMENT POLLUTION
The placement, discharge, or any other introduction of sediment into waters of the commonwealth occurring from the failure to properly design, construct, implement or maintain control measures and control facilities in accordance with the requirements of this chapter.
SEDIMENTATION
The process by which mineral or organic matter is accumulated or deposited by the movement of water.
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.
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
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 Natural Resources Conservation Service (NRCS) that is based on relating soil type and land use/cover to a runoff parameter called "curve number (CN)."
SPILLWAY (EMERGENCY)
A depression in the embankment of a pond or basin, or other overflow structure, that is used to pass peak discharges greater than the maximum design storm controlled by the pond or basin.
STATE WATER QUALITY REQUIREMENTS
The regulatory requirements to protect, maintain, reclaim, and restore water quality under Title 25 of the Pennsylvania Code and the Clean Streams Law.
STORAGE FACILITY
(See "detention basin.")
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 also "return period."
STORM SEWER
A sewer that carries intercepted surface runoff, street water, and other wash waters, or drainage, but excludes domestic sewage and industrial wastes.
STORMWATER
Drainage runoff from the surface of the land resulting from precipitation, snow, or ice melt.
STORMWATER COLLECTION/CONVEYANCE SYSTEM
Natural or engineered structures which 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 HOTSPOT
A land use or activity that generates higher concentrations of hydrocarbons, trace metals, or toxicants than are found in typical stormwater runoff.
STORMWATER MANAGEMENT FACILITIES
Any structure, natural or man-made, that, due to its condition, design, or construction, conveys, stores, or otherwise affects stormwater runoff. Typical stormwater management facilities include, but are not limited to, detention and retention basins, open channels, storm sewers, pipes and infiltration facilities.
STORMWATER MANAGEMENT PLAN
The Washington County Stormwater Management Plan for managing stormwater runoff in Washington County as required by the Act of October 4, 1978, P.L. 864 (Act 167) and known as the "Storm Water Management Act."[5]
STORMWATER MANAGEMENT SITE PLAN (SWM SITE PLAN)
The plan prepared by the applicant or his representative indicating how stormwater runoff will be managed at the project site in accordance with this chapter.
STORMWATER RUNOFF
Waters resulting from snowmelt or precipitation within a drainage basin, flowing over the surface of the ground, collected in channels and conduits, and carried by receiving streams.
STREAM
A watercourse.
STREAM ENCLOSURE
A bridge, culvert, or other structure in excess of 100 feet in length upstream to downstream which encloses a regulated waters of the commonwealth.
SUBAREA
A portion of the watershed that has similar hydrological characteristics and drains to a common point.
SUBWATERSHED AREA
The smallest drainage unit of a watershed for which stormwater management criteria has 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, 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 dwellings, shall be exempt (Pennsylvania Municipalities Planning Code, Act of July 31, 1968, P.L. 805, No. 247[6]).
SWALE
A low-lying stretch of land which gathers or carries surface water runoff.
TIMBER OPERATIONS
See "forest management."
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.
USDA
The United States Department of Agriculture.
VOLUME OF STORMWATER RUNOFF
Quantity of water normally measured in inches, cubic feet, or acre-feet, measured or determined analytically from:
A. 
Runoff coefficients;
B. 
Rainfall/runoff ratios; and
C. 
Areas underneath hydrographs.
WATERCOURSE (WATERWAY)
Any channel of conveyance of surface water having a defined bed and banks, whether natural or artificial, with perennial or intermittent flow.
WATERSHED
The entire region or area drained by a river or other body of water whether natural or artificial. A "designated watershed" is an area delineated by PADEP and approved by the Environmental Quality Board as one for which the county is required to prepare a watershed stormwater management plan in accordance with the Pennsylvania Storm Water Management Act.[7]
WATERS OF THE COMMONWEALTH
Rivers, streams, creeks, rivulets, impoundments, ditches, watercourses, storm sewers, lakes, dammed water, wetlands, ponds, springs and 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 of Pennsylvania.
WETLAND
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 and similar areas. (The term includes but is not limited to wetland areas listed in the State Water Plan, the United States Forest Service Wetlands Inventory of Pennsylvania, the Pennsylvania Coastal Zone Management Plan and a wetland area designated by a river basin commission. This definition is used by the United States Environmental Protection Agency and the United States Army Corps of Engineers.)
[1]
Editor's Note: See 32 P.S. § 679.101 et seq.
[2]
Editor's Note: See 33 U.S.C. § 1313(d).
[3]
Editor's Note: See 53 P.S. § 10503(1.1).
[4]
Editor's Note: See 33 U.S.C. § 1251 et seq,
[5]
Editor's Note: See 32 P.S. § 680.1 et seq.
[6]
Editor's Note: See 53 P.S. § 10101 et seq.
[7]
Editor's Note: See 32 P.S. § 680.1 et seq.
BMPs
Best management practices
CN
Curve number
E&S
Erosion and sedimentation
EV
Exceptional value
FEMA
Federal Emergency Management Agency
HEC-HMS
Hydrologic Engineering Center Hydrologic Modeling System
HQ
High quality
HSG
Hydrologic soil group
LID
Low-impact development
MPC
Pennsylvania Municipalities Planning Code, Act of July 31, 1968, P.L. 805, No. 247[1]
MS4
Municipal separate storm sewer system
NPDES
National Pollutant Discharge Elimination System
NOAA
United States Department of Commerce, National Oceanic and Atmospheric Administration
NRCS
Natural Resources Conservation Service
O&M
Operation and maintenance
PADEP
The Pennsylvania Department of Environmental Protection
PennDOT
Pennsylvania Department of Transportation
PMF
Probable maximum flood
SWM
Stormwater management
Tc
Time of concentration
USDA
United States Department of Agriculture
[1]
Editor's Note: See 53 P.S. § 10101 et seq.