As used in this chapter, the following terms shall have the meanings
indicated:
ACCELERATED EROSION
The removal of the surface of the land through the combined
action of man's activity and the natural processes of a rate
greater than would occur because of the natural process alone.
AGRICULTURAL ACTIVITIES
Activities associated with agriculture such as agricultural
cultivation, agricultural operation, and animal heavy use areas. This
includes the work of producing crops, including tillage, land clearing,
plowing, disking, harrowing, planting, harvesting crops or pasturing
and raising livestock and installation of conservation measures. Construction
of new buildings or impervious area is not considered an agricultural
activity.
ALLUVIAL SOILS (or FLOODPLAIN SOILS)
Areas subject to periodic flooding as defined in the latest
officially issued soil survey information by the U.S. Conservation
and Natural Resources Service.
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; or earth disturbance.
APPLICANT
A landowner or developer who has filed an application for approval to engage in any regulated activities as defined in §
134-4 of this chapter.
AS-BUILT DRAWINGS (or AS-BUILT PLAN)
Plans that are maintained during construction of the project
and which document the actual locations of the site improvements.
As-built plan must be prepared by a professional land surveyor or
professional engineer licensed in the Commonwealth of Pennsylvania.
BANKFULL
The channel at the top of bank or point where water begins
to overflow onto a floodplain.
BASE FLOW
The portion of stream flow that is sustained by groundwater
discharge.
BIORENTENTION
A stormwater retention area which 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 meet state
water quality requirements, to protect and maintain water quality
and groundwater recharge and to otherwise meet the purposes of this
chapter. Stormwater BMPs are commonly grouped into one or two broad
categories or measures: structural or nonstructural. In this chapter,
nonstructural BMPs or measures refer to operational and/or behavior-related
practices that attempt to minimize the contact of pollutants with
stormwater runoff whereas structural BMPs or measures are those 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.
BMP MANUAL
Pennsylvania Best Management Practices Manual, December 2006,
as amended.
CHANNEL
An open drainage feature through which stormwater flows.
Channels include, but shall not be limited to, natural and man-made
watercourses, swales, streams, ditches, canals, and pipes that convey
continuously or periodically flowing water.
CHANNEL EROSION
The widening, deepening, and headward cutting of channels
and waterways, due to erosion caused by moderate to large floods.
CISTERN
An underground reservoir or tank for storing rainwater.
CULVERT
A pipe, conduit, or similar structure, including appurtenant
works, which conveys surface water 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.
DEP
The Pennsylvania Department of Environmental Protection.
DEPARTMENT
The Pennsylvania Department of Environmental Protection.
DESIGN STORM
The magnitude and temporal distribution of precipitation
from a storm event measured in probability of occurrence (e.g., fifty-year
storm) and duration (e.g., 24 hours), used in the design and evaluation
of stormwater management systems. Also see "return period."
DESIGNEE
The agent of Bucks County, Bucks County Conservation District
and/or governing body involved with the administration, review, or
enforcement of any provisions of this chapter by contract or memorandum
of understanding.
DETENTION BASIN
An impoundment structure designed to manage 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.
DETENTION DISTRICT
Those subareas in which some type of detention is required
to meet the plan requirements and goals of Act 167.
DETENTION VOLUME
The volume of runoff that is captured and released into the
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 man-made change to improved or unimproved real estate,
including, but not limited to, the construction or placement of buildings
or other structures, mobile homes, streets and other paving, utilities,
mining, dredging, filling, grading, excavation, or drilling operations,
and the subdivision of land.
DEVELOPMENT PLAN
The provisions for development, including a planned residential
development, a plat of subdivision, all covenants relating to use,
location and bulk of buildings and other structures, intensity of
use or density of development, streets, ways and parking facilities,
common open space and public facilities. The phrase "provisions of
development plan" when used in this chapter shall mean the written
and graphic materials referred to in this definition.
DEVELOPMENT SITE
The specific tract of land for which a regulated activity
is proposed.
DIFFUSED DRAINAGE DISCHARGE
Drainage discharge not confined to a single point location
or channel, such as sheet flow or shallow concentrated flow.
DISCHARGE
(1)
(Verb) To release water from a project, site, aquifer, drainage
basin or other point of interest;
(2)
(Noun) The rate and volume of flow of water, such as in a stream,
generally expressed in cubic feet per second (CFS).
DISCONNECTED IMPERVIOUS AREA (DIA)
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.
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 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.
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 movement of soil particles by the action of water, wind,
ice, or other natural forces.
EXCEPTIONAL VALUE 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 Hilltown 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 internal 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/TIMBER OPERATIONS
Planning and activities necessary for the management of forest
land. 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
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
(1)
(Noun) A slope usually of a street, other public way, land area,
drainage facility or pipe specified in percent;
(2)
(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
from cropland.
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.
HEC-HMS
The US 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 Pennsylvania Code Title 25, Environmental
Protection, 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, 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 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.
HYDROLOGIC REGIME (NATURAL)
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)
A classification of soils by the Natural Resources Conservation
Service, formerly the Soil Conservation Service, 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.
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 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.
INFILL
Development that occurs on smaller parcels that remain undeveloped
but are within or very close proximity to urban areas. The development
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 ground (e.g.,
french drains, seepage pits, seepage trench, biofiltration swale).
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:
(1)
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.
(3)
"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, not greater than 600 square feet in area 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.
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 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:
(1)
A seasonal high-water table, whether perched or regional, determined
by direct observation of the water table or indicated by soil mottling.
(2)
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.
(3)
A rock formation, other stratum or soil condition which is so
slowly permeable that is effectively limits downward passage of effluent.
LOW-IMPACT DEVELOPMENT (LID)
Site design approaches and small-scale stormwater management
practices that promote the use of natural systems for infitration,
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 (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 so long as the flow is not under
pressure.
MUNICIPAL ENGINEER
A professional engineer licensed as such in the Commonwealth of Pennsylvania and appointed by the Township pursuant to Article
V of the Second Class Township Code.
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
government's system for issuance of permits under the Clean Water
Act, which is delegated to PADEP in Pennsylvania.
NRCS
Natural Resource 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 from a stream, river, lake, tidewater
or artificial drain.
PARENT TRACT
The parcel of land from which a land development or subdivision
originates as of the date of adoption of the Stormwater Management
Ordinance on May 8, 2003 (Ordinance No. 2003-2).
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.
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.
PIPE
A culvert, closed conduit, or similar structure (including
appurtenances) that conveys stormwater.
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 (NOAA).
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 § 92.1.
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 help trap coarse materials and other pollutants before
they enter the system.
PROJECT SITE
The specific tract of land where any regulated activity in
the Township is planned, conducted, or maintained.
QUALIFIED DESIGN PROFESSIONAL
Any person licensed by the Pennsylvania Department of State
or otherwise qualified by law and trained to perform work required
by this chapter. Qualifed professionals include professional engineers,
registered landscape architects, and professional land surveyors.
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.
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
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 streambanks, 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.
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.
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 occurring from the failure to
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 underground water (refer to PA BMP Manual, December 2006,
Chapter 6, Section 4).
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).
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 chapter.
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 plan 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 "Stormwater 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.
(1)
Springs or seeps: the point where groundwater discharges to
become surface water.
(2)
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.
(3)
Stream, headwater: the 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, intermittent: a 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, 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 Q7-10 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.
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
As defined in the Pennsylvania Municipalities Planning Code,
Act of July 31, 1968, P.L. 805, No. 247.
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.
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 period from winter to spring, but may be completely
dry for most of the summer and fall.
WATER QUALITY REQUIREMENTS
As defined under state regulations — Protection of
designated and existing uses (Refer 25 Pa. Code Chapters 93 and 96):
(1)
Each stream segment in Pennsylvania has a designated use, such
as cold-water fishery or potable water supply, which is listed in
Chapter 93. These uses must be protected and maintained, under state
regulations.
(2)
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.
(3)
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 streambank, streambed, and structural integrity
of the waterway, to prevent these impacts.
WATER QUALITY VOLUME
A calculated volume of stormwater runoff from impervious
areas which is required to be captured and treated at a site and may
be achieved through use of structural or nonstructural BMPs. Numerically,
the water quality volume is a product of the volumetric runoff coefficient,
the site area, and a depth of rainfall of one inch.
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.
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 water 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)
(1)
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;
(2)
All interstate waters, including interstate wetlands;
(3)
All other waters such as intrastate lakes, rivers, streams (including
intermittent streams), mudflats, sandflats, wetlands, sloughs, prairie
potholes, wet meadows, playa lakes, or natural ponds the use, degradation,
or destruction of which would affect or could affect interstate or
foreign commerce, including any such waters: 1) which are or could
be used by interstate or foreign travelers for recreational or other
purposes; 2) from which fish or shellfish are or could be taken and
sold in interstate or foreign commerce; or 3) which are used or could
be used for industrial purposes by industries in interstate commerce;
(4)
All impoundments of waters otherwise defined as waters of the
United States under this definition;
(5)
Tributaries of waters identified in Subsection B(1) through
(4) of this definition;
(7)
Wetlands adjacent to waters (other than waters that are themselves
wetlands) identified in Subsection B(1) through (6) of this definition.
WATERSHED
Region or area bounded peripherally by water parting and
draining to a particular watercourse or body of water.
WET BASIN
Pond for runoff management that is designed to detain runoff
and always contains water.
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, ferns, and similar areas.
WETLAND DELINEATION
The process by which wetland limits are determined. Wetlands
must be delineated by a qualified specialist according to the 1989
Federal Manuals (as amended) for the Delineation of Jurisdictional
Wetlands (whichever is greater) or according to any subsequent federal
or state regulation. Qualified specialist shall include those persons
being certified professional soil scientists as registered with Registry
of Certified Professionals in Agronomy Crops and Soils (ARCPACS);
or as contained on consultant's list of Pennsylvania Association
of Professional Soil Scientists (PAPSS); or as registered with National
Society of Consulting Soil Scientists (NSCSS), or as certified by
state and/or federal certification programs; or by a qualified biologist/ecologist.