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 at a rate greater
than that which would occur because of natural processes alone.
AGRICULTURAL ACTIVITIES
The work of producing crops and raising livestock, including
tillage, plowing, disking, harrowing, pasturing, mushroom growing,
nursery, and sod operations and installation of conservation measures.
Construction of new buildings or impervious area is not considered
an agricultural activity.
ALTERATION
As applied to land, a change in topography as a result of
the moving of soil and rock from one location or position to another;
also the changing of surface conditions by causing the surface to
be more or less impervious; land disturbance.
APPLICANT
A landowner, developer or other person who has filed an application
to the municipality for approval to engage in any regulated activity
at a project site in the municipality.
AS-BUILT DRAWINGS
Engineering or site drawings maintained by the contractor
as he constructs the project and upon which he documents the actual
locations of the building components and changes to the original contract
documents. These documents, or a copy of same, are turned over to
the municipality at the completion of the project.
BANKFULL
The channel at the top-of-bank or point from where water
begins to overflow onto a floodplain.
BASEFLOW
Portion of stream discharge derived from groundwater; the
sustained discharge that does not result from direct runoff or from
water diversions, reservoir releases, piped discharges, or other human
activities.
BIORETENTION
A stormwater retention area that utilizes woody and herbaceous
plants and soils to remove pollutants before infiltration occurs.
BMP (BEST MANAGEMENT PRACTICE)
Activities, facilities, designs, measures or procedures used
to manage stormwater impacts from regulated activities, to meet state
water quality requirements, to promote groundwater recharge and to
otherwise meet the purposes of this chapter. Stormwater BMPs are commonly
grouped into one of two broad categories or measures: "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.
BUFFER
The area of land immediately adjacent to any stream, measured
perpendicular to and horizontally from the top-of-bank on both sides
of a stream (see "top-of-bank").
CHANNEL
An open drainage feature through which stormwater flows.
Channels include, but shall not be limited to, natural and man-made
drainageways, swales, streams, ditches, canals, and pipes flowing
partly full.
CHANNEL EROSION
The widening, deepening, or headward cutting of channels
and waterways caused by stormwater runoff or bankfull flows.
CISTERN
An underground reservoir or tank for storing rainwater.
CONSERVATION DISTRICT
A conservation district, as defined in Section 3(c) of the
Conservation District Law [3 P.S. § 851(c)], which has the
authority under a delegation agreement executed with the Department
to administer and enforce all or a portion of the erosion and sediment
control program in this commonwealth.
CONVEYANCE
A facility or structure used for the transportation or transmission
of something from one place to another.
CULVERT
A structure with its appurtenant works which carries water
under or through an embankment or fill.
DAM
A man-made barrier, together with its appurtenant works,
constructed for the purpose of impounding or storing water or another
fluid or semifluid. A dam may include a refuse bank, fill, or structure
for highway, railroad, or other purposes which impounds or may impound
water or another fluid or semifluid.
DEP
The Pennsylvania Department of Environmental Protection.
DESIGN STORM
The magnitude and temporal distribution of precipitation
from a storm event measured in probability of occurrence (e.g., a
five-year storm) and duration (e.g., 24 hours), used in the design
and evaluation of stormwater management systems. Also see "return
period."
DETENTION BASIN
An impoundment designed to collect and retard stormwater
runoff by temporarily storing the runoff and releasing it at a predetermined
rate. Detention basins are designed to drain completely soon after
a rainfall event and become dry until the next rainfall event.
DETENTION VOLUME
The volume of runoff that is captured and released into the
waters of this commonwealth at a controlled rate.
DEVELOPER
A person who seeks to undertake any regulated earth disturbance
activities at a project site in the municipality.
DEVELOPMENT
Any human-induced change to improved or unimproved real estate,
whether public or private, including, but not limited to, land development,
construction, installation, or expansion of a building or other structure,
land division, street construction, and site alteration such as embankments,
dredging, grubbing, grading, paving, parking or storage facilities,
excavation, filling, stockpiling, or clearing. As used in this chapter,
development encompasses both new development and redevelopment.
DIAMETER AT BREAST HEIGHT (DBH)
The outside bark diameter at breast height which is defined
as 4.5 feet (1.37 m) above the forest floor on the uphill side of
the tree.
DIFFUSED DRAINAGE DISCHARGE
Drainage discharge that is not confined to a single point
location or channel, including sheet flow or shallow concentrated
flow.
DIRECTLY CONNECTED IMPERVIOUS AREA (DCIA)
An impervious or impermeable surface which is directly connected
to a stormwater drainage or conveyance system, leading to direct runoff,
decreased infiltration, decreased filtration, and decreased time of
concentration.
DISCONNECTED IMPERVIOUS AREA (DIA)
An impervious or impermeable surface which 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
An unstabilized land area where an earth disturbance activity
is occurring or has occurred.
DITCH
A man-made waterway constructed for irrigation or stormwater
conveyance purposes.
DOWNSLOPE PROPERTY LINE
That portion of the property line of the lot, tract, or parcels
of land being developed, located such that overland or pipe flow from
the project site would be directed towards it by gravity.
DRAINAGE CONVEYANCE FACILITY
A stormwater management facility designed to transport stormwater
runoff that includes channels, swales, pipes, conduits, culverts,
and storm sewers.
DRAINAGE EASEMENT
A right granted by a landowner to a grantee allowing the
use of private land for stormwater management purposes.
EARTH DISTURBANCE ACTIVITY
A construction or other human activity which disturbs the
surface of land, including, but not limited to, clearing and grubbing,
grading, excavations, embankments, land development, agricultural
plowing or tilling, timber harvesting activities, road maintenance
activities, mineral extraction, and the moving, depositing, stockpiling,
or storing of soil, rock, or earth materials.
EMERGENCY SPILLWAY
A conveyance area that is used to pass peak discharge greater
than the maximum design storm controlled by the stormwater facility.
ENCROACHMENT
A structure or activity that changes, expands, or diminishes
the course, current, or cross-section of a watercourse, floodway,
or body of water.
EROSION
The natural process by which the surface of the land is worn
away by water, wind or chemical action.
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 anti-degradation).
EXISTING CONDITIONS
The dominant land cover during the five-year period immediately
preceding a proposed regulated activity. If the initial condition
of the site is undeveloped land, the land use shall be considered
as "meadow" unless the natural land cover is proven to generate a
lower curve number or Rational "c" value, such as forested lands.
FEMA
Federal Emergency Management Agency.
FLOOD
A temporary condition of partial or complete inundation of
land areas from the overflow of streams, rivers, and other waters
of this commonwealth.
FLOODPLAIN
Any land area susceptible to inundation by water from any
natural source or delineated by applicable FEMA maps and studies as
being a special flood hazard area. Included are lands adjoining a
river or stream that have been or may be expected to be inundated
by a one-hundred-year flood. Also included are areas that comprise
Group 13 Soils, as listed in Appendix A of the Pennsylvania DEP Technical
Manual for Sewage Enforcement Officers (as amended or replaced from
time to time by PADEP).
FLOODWAY
The channel of a watercourse and those portions of the adjoining
floodplains which 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 the Federal Emergency Management Agency (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-bank.
FLUVIAL GEOMORPHOLOGY
The study of landforms associated with river channels and
the processes that form them.
FOREST MANAGEMENT/TIMBER OPERATIONS
Planning and associated activities necessary for the management
of forest lands. These include timber inventory and preparation of
forest management plans, silvicultural treatment, cutting budgets,
logging road design and construction, timber harvesting, and reforestation.
FREEBOARD
A vertical distance between the elevation of the design high-water
and the top of a dam, levee, tank, basin, swale, or diversion berm.
The space is required as a safety margin in a pond or basin.
GRADE
A.
(noun) A slope, usually of a road, channel, or natural ground
specified in percent and shown on plans as specified herein.
B.
(verb) To finish the surface of a roadbed, the top of an embankment,
or the bottom of an excavation.
GRASSED WATERWAY
A natural or man-made waterway, usually broad and shallow,
covered with erosion-resistant grasses used to convey surface water.
GROUNDWATER
Water beneath the earth's surface that supplies wells and
springs and is often between saturated soil and rock.
GROUNDWATER RECHARGE
The replenishment of existing natural underground water supplies
from rain or overland flow.
HEC-HMS
The U.S. Army Corps of Engineers, Hydrologic Engineering
Center (HEC) — Hydrologic Modeling System (HMS). This model
was used to model the Tookany/Tacony-Frankford Watershed during the
Act 167 plan development and was the basis for the standards and criteria
of this chapter.
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).
HOTSPOTS
Areas where land use or activities generate highly contaminated
runoff, with concentrations of pollutants in excess of those typically
found in stormwater.
HYDROGRAPH
A graph representing the discharge of water versus time for
a selected point in the drainage system.
HYDROLOGIC REGIME
The hydrologic cycle or balance that sustains quality and
quantity of stormwater, baseflow, storage, and groundwater supplies
under 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 NRCS 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 (NRCS).
IMPERVIOUS SURFACE (IMPERVIOUS AREA)
A surface that prevents the infiltration of water into the
ground. Impervious surfaces (or areas) shall include, but not be limited
to, roofs, additional indoor living spaces, patios, garages, storage
sheds and similar structures, and any new streets or sidewalks. Decks,
parking areas, and driveway areas are not counted as impervious areas
if they do not prevent infiltration.
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 remains undeveloped
but is within or in very close proximity to urban or densely developed
areas. Infill development usually relies on existing infrastructure
and does not require an extension of water, sewer, or other public
utilities.
INFILTRATION
Movement of surface water into the soil, where it is absorbed
by plant roots, evaporated into the atmosphere, or percolated downward
to recharge groundwater.
INFILTRATION BASIN
A shallow impoundment that is designed to infiltrate stormwater
into the soil. Infiltration basins are believed to have a high pollutant
removal efficiency, and can also help recharge the groundwater, thus
restoring low flows to stream systems. Infiltration basins can be
problematic at many sites because of stringent soils requirements.
In addition, some studies have relatively high failure rates compared
with other stormwater treatment practices.
INFILTRATION STRUCTURE
A structure designed to direct runoff into the underground
water (e.g., French drains, seepage pits, or seepage trenches).
INFLOW
The flow entering the stormwater management facility and/or
BMP.
INLET
The upstream end of any structure through which water may
flow.
INTERMITTENT STREAM
A stream that flows only part of the time. Flow generally
occurs for several weeks or months in response to seasonal precipitation
or groundwater discharge.
INVERT
The lowest surface, the floor or bottom of a culvert, drain,
sewer, channel, basin, BMP, or orifice.
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 (DEVELOPMENT)
Any of the following activities:
A.
The improvement of one lot or two or more contiguous lots, tracts,
or parcels of land for any purpose involving:
(1)
A group of two or more residential or nonresidential buildings,
whether proposed initially or cumulatively, or a single nonresidential
building on a lot or lots regardless of the number of occupants or
tenure; or
(2)
The division or allocation of land or space, whether initially
or cumulatively, between or among two or more existing or prospective
occupants by means of, or for the purpose of, streets, common areas,
leaseholds, condominiums, building groups, or other features.
C.
Development in accordance with Section 503(1.1) of the PA Municipalities
Planning Code.
LIMITING ZONE
A soil horizon or condition in the soil profile or underlying
a stratum that includes one of the following:
A.
A seasonal high water table, whether perched or regional, determined
by direct observation of the water table or indicated by soil mottling.
B.
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.
C.
A rock formation, other stratum, or soil condition that is so
slowly permeable that it effectively limits downward passage of water.
LOT
A designated parcel, tract, or area of land established by
a plat or otherwise as permitted by law and to be used, developed,
or built upon as a unit.
MAIN STEM (MAIN CHANNEL)
Any stream segment or other runoff conveyance used as a reach
in the Tookany/Tacony-Frankford 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.
MAXIMUM DESIGN STORM
The maximum (largest) design storm that is controlled by
the stormwater facility.
MUNICIPAL ENGINEER
A professional engineer licensed as such in the Commonwealth
of Pennsylvania, duly appointed as the engineer for a municipality,
planning agency, or joint planning commission.
MUNICIPALITY
Cheltenham Township, Montgomery County, Pennsylvania.
NATURAL RECHARGE AREA
Undisturbed surface area or depression where stormwater collects
and a portion of which infiltrates and replenishes the underground
and groundwater.
NONPOINT SOURCE POLLUTION
Pollution that enters a water body from diffuse origins in
the watershed and does not result from discernible, confined, or discrete
conveyances.
NONSTORMWATER DISCHARGES
Water flowing in stormwater collection facilities, such as
pipes or swales, which are not the result of a rainfall event or snowmelt.
NONSTRUCTURAL BEST MANAGEMENT PRACTICE (BMPs)
Methods of controlling stormwater runoff quantity and quality,
such as innovative site planning, impervious area and grading reduction,
protection of natural depression areas, temporary ponding on site,
and other techniques.
NPDES
National Pollutant Discharge Elimination System, the federal
government's system for issuance of permits under the Clean Water
Act, which is delegated to DEP in Pennsylvania.
NRCS
Natural Resource Conservation Service (previously SCS).
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.
OUTFLOW
The flow exiting the stormwater management facility and/or
BMP.
OUTLET
Points of water disposal to a stream, river, lake, tidewater,
or artificial drain.
PARENT TRACT
The parcel of land from which a land development or subdivision
originates, determined from the date of municipal adoption of this
chapter.
PARKING LOT STORAGE
Involves the use of parking areas as temporary impoundments
with controlled release rates during rainstorms.
PEAK DISCHARGE
The maximum rate of stormwater runoff from a specific storm
event.
PIPE
A culvert, closed conduit, or similar structure (including
appurtenances) that conveys stormwater.
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
The period after construction during which disturbed areas
are stabilized, stormwater controls are in place and functioning,
and all proposed improvements in the approved land development 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, but not necessarily designed to meet the water quality volume requirements of §
290-23. For example, any inlets draining to an infiltrating system should be sumped and trapped to prevent the system from becoming clogged with excess sediment.
PROJECT SITE
The specific area of land where any regulated activities
in the municipality are planned, conducted, or maintained.
QUALIFIED PROFESSIONAL
Any person licensed by the Pennsylvania Department of State
or otherwise qualified by law to perform the work required by this
chapter.
REACH
Any stream segment or other runoff conveyance used in the
Tookany/Tacony-Frankford Watershed hydrologic model.
RECHARGE
The replenishment of groundwater through the infiltration
of rainfall, other surface waters, or land application of water or
treated wastewater.
RECONSTRUCTION
Demolition and subsequent rebuilding of impervious surface.
RECORD DRAWINGS
Original documents revised to suit the as-built conditions
and subsequently provided by the Engineer to the client. The Engineer
reviews the contractor's as-builts against his/her own records for
completeness, then either turns these over to the client or transfers
the information to a set of reproducibles, in both cases for the client's
permanent records.
REDEVELOPMENT
Any development that requires demolition or removal of existing
structures or impervious surfaces at a site and replacement with new
impervious surfaces. Maintenance activities such as top-layer grinding
and repaving are not considered to be redevelopment. Interior remodeling
projects and tenant improvements are also not considered to be redevelopment.
REGULATED ACTIVITIES
Any earth disturbances activities or any activities that
involve the alteration or development of land in a manner that may
affect stormwater runoff.
REGULATED EARTH DISTURBANCE ACTIVITY
Defined under NPDES Phase II regulations as earth disturbance
activity of one acre or more with a point source discharge to surface
waters or the municipality's storm sewer system or five acres or more
regardless with or without a point source discharge. This includes
earth disturbance on any portion of, part, or during any stage of
a larger common plan of development. Activity involving earth disturbance
subject to regulation under 25 Pa. Code 92, 25 Pa. Code 102, or the
Clean Streams Law.
RELEASE RATE
The percentage of existing conditions peak rate of runoff
from a site or subarea to which the proposed conditions peak rate
of runoff must be reduced to protect downstream areas.
REPAVING
Replacement of the impervious surface that does not involve
reconstruction of an existing paved (impervious) surface.
REPLACEMENT PAVING
Reconstruction of and full replacement of an existing paved
(impervious) surface.
RETENTION VOLUME; REMOVED RUNOFF
The volume of runoff that is captured and not released directly
into the surface waters of this commonwealth during or after a storm
event.
RETURN PERIOD
The average interval, in years, within which a storm event
of a given magnitude can be expected to recur. For example, the twenty-five-year
return period rainfall would be expected to recur on the average of
once every 25 years.
RISER
A vertical pipe extending from the bottom of a pond that
is used to control the discharge rate from the pond for a specified
design storm.
ROAD MAINTENANCE
Earth disturbance activities within the existing road cross-section,
such as grading and repairing existing unpaved road surfaces, cutting
road banks, cleaning or clearing drainage ditches, and other similar
activities.
ROOF DRAINS
A drainage conduit or pipe that collects water runoff from
a roof and leads it away from the structure.
ROOFTOP DETENTION
The temporary ponding and gradual release of stormwater falling
directly onto flat roof surfaces using controlled-flow roof drains
in building designs.
RUNOFF
Any part of precipitation that flows over the land surface.
SALDO
Subdivision and Land Development Ordinance.
SEDIMENT
Soils or other materials transported by surface water as
a product of erosion.
SEDIMENTATION
The process by which mineral or organic matter is accumulated
or deposited by the movement of water or air.
SEDIMENT BASIN
A barrier, dam, or retention or detention basin located and
designed in such a way as to retain rock, sand, gravel, silt, or other
material transported by water during construction.
SEDIMENT POLLUTION
The placement, discharge, or any other introduction of sediment
into the waters of the commonwealth.
SEEPAGE PIT; SEEPAGE TRENCH
An area of excavated earth filled with loose stone or similar
coarse material into which surface water is directed for infiltration
into the underground water.
SEPARATE STORM SEWER SYSTEM
A conveyance or system of conveyances (including roads with
drainage systems, municipal streets, catch basins, curbs, gutters,
ditches, man-made channels, or storm drains) primarily used for collecting
and conveying stormwater runoff.
SHALLOW CONCENTRATED FLOW
Stormwater runoff flowing in shallow, defined ruts prior
to entering a defined channel or waterway.
SHEET FLOW
A flow process associated with broad, shallow water movement
on sloping ground surfaces that is not channelized or concentrated.
SOIL COVER COMPLEX METHOD
A method of runoff computation developed by NRCS that is
based on relating soil type and land use/cover to a runoff parameter
called "curve number" (CN).
SPILLWAY
A conveyance that is used to pass the peak discharge of the
maximum design storm that is controlled by the stormwater facility.
STATE WATER QUALITY REQUIREMENTS
The regulatory requirements to protect, maintain, reclaim,
and restore water quality under Title 25 of the Pennsylvania Code
and the Clean Streams Law. This requires protection of designated and existing uses
(see 25 Pa. Code Chapters 93 and 96), including:
A.
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.
B.
"Existing uses" are those attained as of November 1975, regardless
of whether they have been designated in Chapter 93. Regulated earth
disturbance activities 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.
C.
Water quality involves the chemical, biological, and physical
characteristics of surface water bodies. After regulated earth disturbance
activities are complete, these characteristics can be impacted by
the addition of pollutants such as sediment and changes in habitat
through increased flow volumes and/or rates as a result of changes
in land surface area from those activities. Therefore, permanent discharges
to surface waters must be managed to protect the stream bank, stream
bed, and structural integrity of the waterway to prevent these impacts.
STORAGE INDICATION METHOD
A reservoir routing procedure based on solution of the continuity
equation (inflow minus outflow equals the change in storage) with
outflow defined as a function of storage volume and depth.
STORM FREQUENCY
The number of times that a given storm "event" occurs or
is exceeded on the average in a stated period of years (see "return
period").
STORM SEWER
A system of pipes and/or open channels that convey intercepted
runoff and stormwater from other sources but exclude domestic sewage
and industrial wastes.
STORMWATER
Drainage runoff from the surface of the land resulting from
precipitation or snow or ice melt.
STORMWATER MANAGEMENT DISTRICT
Those subareas of a watershed in which some type of detention
is required to meet the plan requirements and the goals of Act 167.
STORMWATER MANAGEMENT FACILITY
Any structure, natural or man-made, that, due to its condition,
design, or construction, conveys, stores, or otherwise affects stormwater
runoff quality, rate, or quantity. Typical stormwater management facilities
include, but are not limited to, detention and infiltration basins,
open channels, storm sewers, pipes, and infiltration structures.
STORMWATER MANAGEMENT PLAN
The watershed plan, known as the "Tookany/Tacony-Frankford
Watershed Act 167 Stormwater Management Plan," for managing those
land use activities that will influence stormwater runoff quality
and quantity and that would impact the Tookany/Tacony-Frankford Watershed
adopted by Montgomery and Philadelphia Counties as required by the
Act of October 4, 1978, P.L. 864 (Act 167).
STORMWATER MANAGEMENT SITE PLAN
The plan prepared by the applicant or his representative
indicating how stormwater runoff will be managed at the particular
site of interest to meet the requirements of this chapter.
STREAM BUFFER
The land area adjacent to each side of a stream essential
to maintaining water quality (see "buffer").
STREAM ENCLOSURE
A bridge, culvert, or other structure in excess of 100 feet
in length upstream to downstream which encloses a regulated water
of the commonwealth.
SUBAREA (SUBWATERSHED)
The smallest drainage unit of a watershed for which stormwater
management criteria have been established in the stormwater management
plan.
SUBDIVISION
The division or redivision of a lot, tract, or parcel of
land by any means into two or more lots, tracts, parcels, or other
divisions of land, including changes in existing lot lines for the
purpose, whether immediate or future, of lease, partition by the court
for distribution to heirs or devisees, transfer of ownership, or building
or lot development; provided, however, that the subdivision by lease
of land for agricultural purposes into parcels of more than 10 acres
not involving any new street or easement of access or any residential
dwelling shall be exempted; as defined in the Pennsylvania Municipalities
Planning Code, Act of July 31, 1968, P.L. 805, No. 247.
SURFACE WATERS OF THE COMMONWEALTH
Any and all rivers, streams, creeks, rivulets, ditches, watercourses,
storm sewers, lakes, dammed water, wetlands, ponds, springs, and all
other bodies or channels of conveyance of surface waters, or parts
thereof, whether natural or artificial, within or on the boundaries
of the commonwealth.
SWALE
A low-lying stretch of land that gathers or carries surface
water runoff.
TIME-OF-CONCENTRATION (TC)
The time required for surface runoff to travel from the hydraulically
most distant point of the watershed to a point of interest within
the watershed. This time is the combined total of overland flow time
and flow time in pipes or channels, if any.
TOP-OF-BANK
The 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.
USDA
United States Department of Agriculture.
VERNAL POND
Seasonal depressional wetlands that are covered by shallow
water for variable periods from winter to spring but may be completely
dry for most of the summer and fall.
WATERCOURSE
A channel or conveyance of surface water having a defined
bed and banks, whether natural or artificial, with perennial or intermittent
flow.
WATERSHED
The region or area drained by a river, watercourse or other
surface water of the commonwealth.
WATERS OF THE COMMONWEALTH
Rivers, streams, creeks, rivulets, impoundments, ditches,
watercourses, storm sewers, lakes, dammed water, wetlands, ponds,
springs and other bodies or channels of conveyance of surface and
underground water, or parts thereof, whether natural or artificial,
within or on the boundaries of this commonwealth.
WELLHEAD
A.
A structure built over a well.
B.
The source of water for a well.
WELLHEAD PROTECTION AREA
The surface and subsurface area surrounding a water supply
well, well field, or spring supplying a public water system through
which contaminants are reasonably likely to move toward and reach
the water source.
WET BASIN
A pond for urban runoff management that is designed to detain
urban 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. Wetlands
generally include swamps, marshes, bogs, fens, and similar areas.
WOODS
A natural ground cover with more than one viable tree of
a DBH of six inches or greater per 1,500 square feet which existed
within three years of application; a cover condition for which SCS
curve numbers have been assigned or to which equivalent Rational Method
runoff coefficients have been assigned.