Township of Solebury, 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 where all overland or pipe flow from the proposed development is directed.

DOWNSTREAM HYDRAULIC CAPACITY ANALYSIS

Any downstream capacity hydraulic analysis conducted in accordance with this chapter shall use the following criteria for determining adequacy for accepting increased peak flow rates:

Natural or man-made channels or swales must be able to convey the increased rate of runoff associated with a two-year return period event within their banks at velocities consistent with protection of the channels from erosion. Acceptable velocities shall be based upon criteria included in the DEP Erosion and Sediment Pollution Control Program Manual.

Natural or man-made channels or swales must be able to convey the increased twenty-five-year return period rate of runoff without creating any hazard to persons or property.

DRAINAGE CONVEYANCE FACILITY

Culverts, bridges, storm sewers or any other facilities which must pass or convey flows from the tributary area must be designed in accordance with DEP 25 Pa. Code, Chapter 105 regulations (if applicable) and, at a minimum, pass the increased twenty-five-year return period rate of runoff.

(4)

No new channels or conveyance facilities shall be authorized by this language.

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.

DRY POND (DRY EXTENDED DETENTION POND)

Dry extended detention ponds do not maintain a permanent pool between storm events. Outlets are designed to detain the volume of a water quality design storm for a minimum (usually 48 hours) to allow for the settling of particles and associated pollutants. In addition, dry extended detention ponds provide flood control by including additional temporary storage for peak flows above the dead storage. Extended detention ponds are also capable of managing smaller floods that contribute to channel erosion problems and occur more frequently than the annual or two-year flood.

EARTH DISTURBANCE (OR EARTH DISTURBANCE ACTIVITY)

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; building construction; and the moving, depositing, stockpiling or storing of soil, rock or earth materials.

[Amended by Ord. No. 2022-005, 9/6/2022]

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 WATERS

Surface waters of high quality which satisfy 25 Pa. Code, Chapter 93, "Water Quality Standards," § 93.413(b) (relating to antidegradation).

EXISTING CONDITIONS

The dominant land cover during the five-year period immediately preceding a proposed regulated activity.

[Amended by Ord. No. 2022-005, 9/6/2022]

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.

[Added by Ord. No. 2022-005, 9/6/2022[2]]

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

Any land area susceptible to inundation by water from any natural source or delineated as a special flood hazard area on the applicable National Flood Insurance Program Flood Insurance Rate Map (FIRM) prepared by the Federal Emergency Management Agency (FEMA). 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).

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 from the top of the bank of the stream.

FOREST MANAGEMENT/TIMBER OPERATIONS

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

[Amended by Ord. No. 2022-005, 9/6/2022]

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.

GEOLOGIST

A licensed professional geologist registered in the Commonwealth of Pennsylvania.

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.

[Added by Ord. No. 2022-005, 9/6/2022]

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 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 25 Pa. Code, Chapter 93, "Water Quality Standards," § 93.4b(a).

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, § 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 23-G of this chapter.

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 HSG's (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 US 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.

[Amended by Ord. No. 2022-005, 9/6/2022]

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 (OR IMPERVIOUS AREA)

Surfaces which 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 to be impervious within the meaning of this definition shall be classified as impervious surfaces.

[Amended by Ord. No. 2022-005, 9/6/2022]

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.

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.

(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.

LIMIT OF EARTH DISTURBANCE

"Land development" does not include development which involves:

(a)

The conversion of an existing single-family detached dwelling or single-family semidetached 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 farm building, on a lot or lots subordinate to an existing principal building.

(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.

LAND/EARTH DISTURBANCE

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.

LANDSCAPE ARCHITECT

A person who engages or offers to engage in the practice of landscape architecture in the Commonwealth of Pennsylvania under the authority of the Landscape Architects Registration Law, 63 P.S. § 901 et seq.

The perimeter of earth disturbance on a site.

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 is 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.

[Amended by Ord. No. 2022-005, 9/6/2022]

MAIN STEM (MAIN CHANNEL)

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

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 when the flow is not under pressure.

MUNICIPALITY

Solebury Township, Bucks County, Pennsylvania.

NONPOINT SOURCE POLLUTION

Pollution that enters a watery 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 governments system of regulations for the issuance of permits under the Clean Water Act, 33 U.S.C.A. § 1251 et seq., which is delegated to PADEP in Pennsylvania.

NRCS

USDA Natural Resource Conservation Service (previously SCS).

[Amended by Ord. No. 2022-005, 9/6/2022]

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

"The point source" as described in 40 CFR 122.2 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.

PARENT TRACT

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

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 and that is subject to a recorded conservation easement, in perpetuity, in a manner acceptable to the Township.

PERSON

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

PERVIOUS AREA (or PERVIOUS SURFACE)

A surface that allows the infiltration of water into the ground.

[Amended by Ord. No. 2022-005, 9/6/2022]

PIPE

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

PLANNING COMMISSION

The Planning Commission of the Township.

PMF (PROBABLE MAXIMUM FLOOD)

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 (NOAH).

POINT SOURCE

Any discernible, confined and discrete conveyance, including, but not limited to, any pipe, ditch, channel, tunnel or conduit from which stormwater as defined in state regulations at 25 Pa. Code § 92.1, is or may be discharged.

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 stormwater management or infiltration system.

PROJECT SITE

The specific tract of land where any regulated activity in the Township is planned, conducted, or maintained.

[Amended by Ord. No. 2022-005, 9/6/2022]

QUALIFIED PROFESSIONAL

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

[Added by Ord. No. 2022-005, 9/6/2022]

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 ACTIVITIES

Any activity to which this chapter is applicable pursuant to § 23-104 of this chapter.

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, 35 P.S. § 691.1 et seq.

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.

[Amended by Ord. No. 2022-005, 9/6/2022]

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 BUFFER

A permanent area of trees and shrubs located adjacent to streams, lakes, ponds and wetlands.

[Added by Ord. No. 2022-005, 9/6/2022]

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 an 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.

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.

[Added by Ord. No. 2022-005, 9/6/2022]

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/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, § 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 GROUP, HYDROLOGIC

A classification of soils by the NRCS into four runoff potential groups. The groups range from A soils, which are very permeable and produce little runoff to D soils, which are not very permeable and produce much more runoff.

SOIL SCIENTIST

An individual trained to observe and identify soil properties that can be used to determine such things as depth to seasonal high water table, soil permeability, potential productivity and other potentially use-limiting soil features.

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 25 Pa. Code, Chapter 93, "Water Quality Standards," as exceptional value (EV) or high quality (HQ) waters.

STATE WATER QUALITY REQUIREMENTS

The regulatory requirements to protect, maintain, reclaim, and restore water quality under Title 25 ofthe Pennsylvania Code and the Clean Streams Law.[3]

[Added by Ord. No. 2022-005, 9/6/2022]

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 "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

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

[Amended by Ord. No. 2022-005, 9/6/2022]

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 Board of Supervisors after the drainage plan has been approved. Said permit is issued prior to or with the final Township approval.

STORMWATER MANAGEMENT PLAN

The plan for managing stormwater runoff within the Township adopted as required by the Act of October 4, 1978, P.L. 864, (Act 167), 32 P.S. § 680.1 et seq.

STORMWATER MANAGEMENT SITE PLAN

The plan prepared by the developer or his representative indicating how stormwater runoff will be managed at the development site in accordance with this chapter. Stormwater management site plan may also be designated as SWM site plan throughout this chapter.

[Amended by Ord. No. 2022-005, 9/6/2022]

STREAM

Rivers, creeks, springs and other watercourses containing water at least on a seasonal basis during an average water year. The term "stream" shall include the following:

	SPRINGS OR SEEPS — The point where groundwater discharges to become surface water.
	STREAM, EPHEMERAL — A 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 stream beds 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. The term often used interchangeably with intermittent stream but the difference is in the length of time of continuous flow (less than one month per year).
	STREAM, HEADWATER — The beginning reach of a stream that 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.
	STREAM, INTERMITTENT — A reach of stream that flows only during wet periods of the year (30% to 90% of the time) and flows in a continuous well-defined channel. During dry periods, especially in summer months, intermittent streams may go down to a trickle of water and make it appear dry, when in fact there is water flowing through the stream bottom or "substrate." This is usually caused by the seasonal changes of the local soil water table or during periods of long-term drought.
	STREAM, PERENNIAL — A 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 meshs 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 BUFFER

The land area adjacent to each side of a stream, essential to maintaining water quality, measured perpendicular to and horizontally from the top-of-bank.

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.

STREAMBANK EROSION

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

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, 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.

[Amended by Ord. No. 2022-005, 9/6/2022]

SURVEYOR

An individual licensed and registered under the laws of the Commonwealth of Pennsylvania to engage in the practice of land surveying.

SWALE

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

TIME OF CONCENTRATION (TC)

The time for surface runoff to travel from the hydraulically most distant point of the watershed to a point of interest within the watershed. This time is the combined total of overland flow time and flow time in pipes or channels, if any.

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.

TOWNSHIP

Solebury Township, Bucks County, Pennsylvania.

TOWNSHIP ENGINEER

A professional engineer licensed as such in the Commonwealth of Pennsylvania and appointed by the Township pursuant to Article XII of the Second Class Township Code, 53 P.S. § 66201 et seq.

TRIBUTARY AREA

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

USDA

United States Department of Agriculture.

[Added by Ord. No. 2022-005, 9/6/2022]

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 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 25 Pa. Code, 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 25 Pa. Code, 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.