Township of Plumstead, PA Definitions.

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

DISCONNECTED IMPERVIOUS AREA (DIA)

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

An impervious surface that is disconnected from any stormwater drainage or conveyance system and is redirected or directed to a pervious area, which allows for infiltration, filtration, and increased time of concentration.

DISTURBED AREAS

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.

DOWNSTREAM HYDRAULIC CAPACITY ANALYSIS

Any downstream capacity hydraulic analysis conducted in accordance with this Part.

DRAINAGE CONVEYANCE FACILITY

A stormwater management facility designed to transmit stormwater runoff which 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.

DRAINAGE PERMIT

A permit issued by the Township after the SWM plan has been approved.

EARTH DISTURBANCE

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

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.

ENGINEER

A licensed professional civil engineer registered by the Commonwealth of Pennsylvania.

EROSION

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

EROSION AND SEDIMENT POLLUTION CONTROL PLAN

A site-specific plan identifying the BMPs to minimize accelerated erosion and sedimentation, pursuant to 25 Pa Code Chapter 102.

EXCEPTIONAL VALUE (EV) WATERS

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

EXISTING CONDITIONS

The initial condition of a project site prior to the proposed construction.

EXISTING RECHARGE AREA

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

EXISTING RESOURCES AND SITE ANALYSIS MAP

A base map which identifies fundamental environmental site information, including floodplains, wetlands, topography, vegetative site features, natural areas, prime agricultural land and areas supportive of endangered species.

FEMA

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 this commonwealth.

FLOODPLAIN

Those areas of Plumstead Township which are subject to the 100-year flood, as identified in the Flood Insurance Study (FIS) dated May 18, 1999, as amended, and the accompanying maps prepared for the Township by the Federal Emergency Management Agency (FEMA), or most recent revision thereof; and also those areas along streams, ponds, or lakes not identified within the Flood Insurance Study which are inundated by the 100-year reoccurrence interval flood. Also includes areas that comprise Group 13 Soils, as listed in Appendix A of the Pennsylvania DEP Technical Manual for Sewage Enforcement Officers (as amended or replaced from time to time by PADEP).

FLOODWAY

The channel of the watercourse and those portions of the adjoining floodplains that are reasonably required to carry and discharge the 100-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 100-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 MANAGEMENT OR TIMBER OPERATIONS

Planning and associated activities necessary for the management of forests. 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, or diversion ridge. The space is required as a safety margin in a pond or basin.

GRADE

(noun) A slope usually of a street, other public way, land area, drainage facility or pipe specified in percent;

HYDROLOGIC REGIME, NATURAL

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

GRASSED WATERWAY

A natural or constructed waterway, usually broad and shallow, covered with erosion-resistant grasses, used to conduct 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

Replenishment of natural underground water supplies.

HEC-HMS

The U.S. Army Corps of Engineers, Hydrologic Engineering Center (HEC) - Hydrologic Modeling System (HMS).

HIGH QUALITY (HQ) 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). The Paunacussing Creek is designated as a high quality watershed.

HOT SPOT

An area where land use or activity generates highly contaminated runoff, with concentrations of pollutants in excess of those typically found in stormwater. Typical pollutant loadings in stormwater may be found in Chapter 8, Section 6, of the Pennsylvania Stormwater Best Management Practices Manual, Pennsylvania Department of Environmental Protection (PADEP) No. 363-0300-002 (2006). More information concerning hot spots may be found in Appendix H of this Part.[1]

HYDRIC SOIL

A soil that is saturated, flooded, or ponded long enough during the growing season to develop an anaerobic condition in the upper part.

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

HYDROLOGIC SOIL GROUP (HSG)

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

HYETOGRAPH

A graphical representation of average rainfall, rainfall excess rates, or volumes over specified areas during successive units of time during a storm.

IMPERVIOUS SURFACE

Those surfaces that prevent the infiltration of water into the ground. All buildings, parking areas, driveways, roads, sidewalks, swimming pools, and any areas containing concrete, asphalt, packed stone, compacted soils, or other equivalent surfaces shall be considered impervious within this definition. In addition, other areas determined by the Township Engineer and/or the Township Zoning Officer to be impervious within the meaning of this definition shall be classified as impervious surfaces.

IMPOUNDMENT

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

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 ground (e.g., french drains, seepage pits, seepage trench, biofiltration swale, infiltration basins).

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.

INVERT

The inside bottom of a culvert or other conduit.

KARST

A type of topography or landscape characterized by surface depressions, sinkholes, rock pinnacles/uneven bedrock surface, underground drainage and caves. Karst is formed on carbonate rocks, such as limestone or dolomite.

LAND DEVELOPMENT

Any of the following activities:

The improvement of one or two or more contiguous lots, tracts or parcels of land for any purpose involving:

(a)

A group of two or more residential or nonresidential buildings, whether purposed initially or cumulatively, or a single nonresidential building on a lot or lots regardless of the number of occupants or tenure; or

(b)

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.

LAND OR EARTH DISTURBANCE

"Land development" does not include development which involves:

(a)

The conversion of an existing single-family detached dwelling or single-family semi-detached dwelling into not more than three residential units, unless such units are intended to be a condominium;

(b)

The addition of a residential accessory building, including a farm building, on a lot or lots subordinate to an existing principal building; or

(c)

The addition or conversion of buildings or rides within the confines of an enterprise which would be considered an amusement park. For the purposes of this subsection, an amusement park is defined as a tract or area used principally as a location for permanent amusement structures or rides. This exclusion shall not apply to newly acquired acreage by an amusement park until initial plans for the expanded area have been approved by the proper authorities.

Any activity involving grading, tilling, digging, or filling of ground or stripping of vegetation or any other activity that causes an alteration to and destabilization of the natural condition of the land.

LIMITING ZONE

A soil horizon or condition in the soil profile or underlying strata which 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.

LOW IMPACT DEVELOPMENT (LID)

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

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

MAIN STEM or MAIN CHANNEL

Any stream segment or other runoff conveyance facility used as a reach in the watershed hydrologic model.

MANNING EQUATION or 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 when the flow is not under pressure.

MUNICIPAL ENGINEER or TOWNSHIP ENGINEER

A professional engineer licensed in the Commonwealth of Pennsylvania and appointed by the Township pursuant to Article V of the Second Class Township Code.

MUNICIPALITY or TOWNSHIP

Plumstead Township, Bucks County, Pennsylvania.

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.

NPDES

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

NRCS

Natural Resources Conservation Service (previously 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 flowing partly full.

OUTFALL

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

OUTLET

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

PADEP

The Pennsylvania Department of Environmental Protection (PADEP).

PARENT TRACT

The parcel of land from which a land development or subdivision originates as of the date of adoption of the initial Plumstead Township Stormwater Management Ordinance on July 18, 2000, (Ordinance No. 00-7-18-1).

PEAK DISCHARGE

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

PENN STATE RUNOFF MODEL (CALIBRATED)

The computer-based hydrologic modeling technique adapted to the watershed for the Act 167 plan. The model has been "calibrated" to reflect actual recorded flow values by adjoining key model input parameters.

PERMANENTLY PRESERVED LAND

A parcel or tract of land that is subject to a recorded conservation easement, in perpetuity, in a manner acceptable to the Township.

PERMANENTLY REMOVED VOLUME (PRV)

The volume of runoff that is permanently removed from the runoff and not released into surface waters of the commonwealth during or after a storm event.

PERSON

An individual, partnership, association, corporation or other entity.

PERVIOUS AREA

Any area not defined as impervious.

PIPE

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

PLANNING COMMISSION

The Planning Commission of Plumstead 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 controls are in place and functioning, and all improvements in the approved SWM plan are completed.

PRETREATMENT

Techniques employed in stormwater BMPs to provide storage or filtering to trap coarse materials and other pollutants before they enter the system.

PROBABLE MAXIMUM FLOOD (PMF)

The flood that may be expected from the most severe combination of critical meteorologic and hydrologic conditions that are 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 tract of land where any regulated activity in the Township is planned, conducted or maintained.

QUALIFIED PROFESSIONAL

Any person licensed by the Pennsylvania Department of State or otherwise qualified by law and trained to perform work required by this Part. Qualified professionals include professional engineers, registered landscape architects, and professional land surveyors.

RATIONAL METHOD

A rainfall-runoff relation used to estimate peak flow.

RECHARGE AREA

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

RECHARGE VOLUME

A calculated volume of stormwater runoff from impervious areas which is required to be infiltrated at a site and may be achieved through use of structural or nonstructural BMPs.

REGULATED ACTIVITY

Any activity to which this Part is applicable pursuant to § 26-104 of this Part.

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.[2]

RELEASE RATE

The percentage of predevelopment peak rate of runoff from a site or subarea to which the post development peak rate of runoff must be reduced to protect downstream areas.

RETENTION BASIN

A basin designed to retain stormwater runoff so that a permanent pool is established.

RETENTION VOLUME/REMOVED RUNOFF

The volume of runoff that is captured and not released directly into the surface waters of the 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.

RIPARIAN CORRIDOR or RIPARIAN BUFFER

A vegetated ecosystem along a water body that serves to buffer the water body from the effects of runoff by providing water quality filtering, bank stability, recharge, rate attenuation and volume reduction, and shading of the water body by vegetation. Riparian corridors also provide habitat and may include stream banks, wetlands, floodplains, and transitional areas.

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 a structure.

RUNOFF

Any part of precipitation that flows over the land surface.

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 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.

SEDIMENTATION

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

SEEPAGE PIT or 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 (refer PA BMP Manual, December 2006, Chapter 6, Section 4).

SEPARATE STORM SEWER SYSTEM

A system of pipes, open channels, streets, and other conveyances intended to carry stormwater runoff.

SHALLOW CONCENTRATED FLOW

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

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 NRCS that is based on relating soil type and land use/cover to a runoff parameter called a 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 in Pennsylvania Code Title 25, Environmental Protection, Chapter 93, Water Quality Standards, as exceptional value (EV) or high quality (HQ) waters.

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. Refer to "return period."

STORM SEWER

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

STORMWATER

The surface runoff generated by precipitation reaching the ground surface, or by snow or ice melt.

STORMWATER MANAGEMENT (SWM) SITE PLAN

The plan prepared by the developer or his qualified professional indicating how stormwater runoff will be managed at the particular site of interest according to this Part.

STORMWATER MANAGEMENT FACILITY

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, infiltration structures, and other BMPs.

STORMWATER MANAGEMENT PERMIT

A permit issued by the Township after the drainage plan has been approved. Said permit is issued prior to or with the final Township approval of the proposed development activity.

STORMWATER MANAGEMENT PLAN

The plans for managing stormwater runoff within the Township adopted as required by the Act of October 4, 1978, P.L. 864 (Act 167), as amended, and known as the "Storm Water Management Act."

STREAM

Rivers, creeks, springs, and other perennial or intermittent watercourses containing water at least on a seasonal basis during an average water year. The term "stream" shall include all "intermittent streams" and all "perennial streams."

SPRINGS or SEEPSThe point where groundwater discharges to become surface water.

STREAM, EPHEMERALA reach of stream that flows only during and for short periods following precipitation, and flows in low areas that may or may not be a well-defined channel. Ephemeral streambeds are located above the water table year round. Groundwater is not a source of water for the stream. Some commonly used names for ephemeral streams include: stormwater channel, drain, swale, gully, dry stream channel, hollow, or saddle.

TIME OF CONCENTRATION (Tc)

STREAM, HEADWATERThe beginning reach of a stream, which collects water from springs and seeps and provides a hydrologic connection to a perennial stream. These channels may be ill defined and may move from year to year depending upon groundwater input, snowmelt, and runoff, but are typified by hydric soils and hydric vegetation.

(4)

STREAM, INTERMITTENTA reach of stream that flows only during wet periods of the year and flows in a continuous well-defined channel. During dry periods, when the water table is depressed by seasonal aridity or drought, intermittent streams may go down to a trickle of water and appear dry, when in fact there is water flowing within the stream bottom or "substrate."

(5)

STREAM, PERENNIAL or WATERCOURSE, PERENNIALA body of water in a channel that flows throughout a majority of the year in a defined channel and is capable, in the absence of pollution, drought, or man-made stream disturbances, of supporting a benthic macroinvertebrate community that is composed of two or more recognizable taxonomic groups of organisms, large enough to be seen by the unaided eye and can be retained by a U.S. Standard No. 30 sieve (28 mesh per inch, 0.595 mm openings) and live at least part of their life cycles within or upon available substrates in a body of water or water transport system. A perennial stream can have Q_7-10 flow of zero. For the purposes of this document, a perennial stream includes lakes and ponds.

STREAM BANK EROSION

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

STREAM BUFFER

The land area adjacent to each side of a stream, essential to maintaining water quality.

STREAM ENCLOSURE

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

SUBAREA or SUBWATERSHED

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

SUBDIVISION

As defined in the Pennsylvania Municipalities Planning Code, Act of July 31, 1968, P.L. 805, No. 247.[3]

SWALE

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

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.

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.

TRIBUTARY AREA

The portion of a watershed that contributes runoff to a particular point in that watershed.

USDA

United States Department of Agriculture.

VERNAL POOL

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.

VOLUMETRIC RUNOFF COEFFICIENT

A variable indicative of stormwater runoff volume and dependent on the impervious coverage for a site.

WATER QUALITY REQUIREMENTS

As defined under state regulations, protection of designated and existing uses (refer to 25 Pa Code Chapters 93 and 96):

Each stream segment in Pennsylvania has a "designated use," such as "cold water fishery" or "potable water supply," which are listed in Chapter 93. These uses must be protected and maintained, under state regulations.

"Existing uses" are those attained as of November 1975, regardless whether they have been designated in Chapter 93. Land development must be designed to protect and maintain existing uses 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.

WATERS OF THE COMMONWEALTH

Water quality involves the chemical, biological, and physical characteristics of surface water bodies. After land development, these characteristics can be impacted by addition of pollutants such as sediment, and changes in habitat through increased flow volumes and/or rates. Therefore, discharge to surface waters must be designed and managed to protect the stream bank, streambed, and structural integrity of the waterway, to prevent these impacts.

WATERCOURSE

An intermittent or perennial stream of water, river, brook, creek, or swale identified on USGS or SCS mapping; and/or delineated waters of the commonwealth.

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

WATERS OF THE UNITED STATES or WATERS OF THE US

All waters which are currently used, were used in the past, or may be susceptible to use in interstate or foreign commerce, including all waters which are subject to the ebb and flow of the tide;

All interstate waters, including interstate wetlands;