Definitions. As used in this chapter, the following
terms shall have the meanings indicated:
AGRICULTURAL ACTIVITIES
The work of producing crops and raising livestock, including
tillage, plowing, disking, harrowing, pasturing 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 or developer who has filed an application for approval to engage in any regulated activities as defined in §
200-5 of this chapter.
BUFFER AREA
Area that is protected from development in order to prevent
degradation of the water body or water quality.
CAPTURE DEPTH
Depth of runoff captured from a given area and either allowed
to evaporate, infiltrate, or be discharged through a spillway at a
negligible rate.
CARBONATE
A sediment formed by the organic or inorganic precipitation
of mineral compounds characterized by the fundamental chemical ion
CO3, the principal element in limestone and
dolomite strata.
CHANNEL
A perceptible natural or artificial waterway, which periodically
or continuously contains moving water having a definite bed and banks,
which confine the water.
CLOSED OR UNDRAINED DEPRESSION
In a karst geologic area a distinct bowl-shaped depression
in the land surface; size and amplitude are variable; drainage is
internal. It differs from a sinkhole in that the ground surface is
unbroken and usually occurs in greater density per unit area.
CREDITS
A deduction from the required amount. In this chapter, implies
reduction of required water quality volumes due to using a recommended
practice.
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.
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.
DESIGNEE
The agent of a Planning Commission and/or agent of the governing
body involved with the administration, review or enforcement of any
provisions of this chapter by contract or memorandum of understanding.
DETENTION BASIN
An impoundment structure designed to manage stormwater runoff
by temporarily storing the runoff and releasing it at a predetermined
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 SITE
The specific tract of land for which a regulated activity
is proposed.
DOLOMITE
(1)
A mineral consisting of calcium magnesium carbonate found as
compact limestone; or
(2)
Limestone or marble rich in magnesium carbonate.
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 towards it.
DRAINAGE CONVEYANCE FACILITY
A stormwater management facility designed to transmit stormwater
runoff and shall include streams, channels, swales, pipes, conduits,
culverts, storm sewers, etc.
DRAINAGE EASEMENT
A right granted by a landowner to a grantee, allowing the
use of private land for stormwater management purposes.
DRAINAGEWAY
The natural or man-made path of surface water from a given
area.
EROSION
The movement of soil particles by the action of water, wind,
ice or other natural forces.
EXFILTRATION
The process by which water or moisture moves from a subsurface
trench, bed or other feature into the subsoil. Exfiltration is best
measured by a soil's percolation rate.
EXISTING CONDITIONS
The initial condition of a project site prior to the proposed
construction.
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 by applicable Department of Housing and
Urban Development, Federal Insurance Administration Flood Hazard Boundary
Map as being a special flood hazard area.
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 activities necessary for the management of forestland.
These include timber inventory and preparation of forest management
plans, silvicultural treatment, cutting budgets, logging road design
and construction, timber harvesting, site preparation and reforestation.
FREEBOARD
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.
GRASSED WATERWAY
A natural or constructed waterway, usually broad and shallow,
covered with erosion-resistant grasses, used to conduct surface water
from cropland.
IMPOUNDMENT
A retention or detention basin designed to retain stormwater
runoff and release it at a controlled rate.
INFILTRATION RATE
The infiltration rate of a soil is related to the soil's
final infiltration capacity and represents the rate at which water
enters the soil/air interface at the top of the soil profile. Infiltration
rates are measured in units of length/time.
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.
INTERCEPTOR
A channel, berm, or dike constructed across a slope for the
purpose of intercepting stormwater, reducing the velocity of flow,
and diverting it to outlets where it may be disposed.
KARST
A type of topography that is formed over limestone, dolomite,
or gypsum by bedrock solution, and that is characterized by closed
depressions or sinkholes, caves, and underground drainage (from AGI,
Glossary of Geology, 1972).
LAND DEVELOPMENT
(1)
The improvement of one lot or two or more contiguous lots, tracts,
or parcels of land for any purpose involving:
(a)
A group of two or more buildings; or
(b)
The division or allocation of land or space between or among
two or more existing or prospective occupants by means of or for the
purpose of streets, common areas, leaseholds, condominiums, building
groups, or other features;
(3)
Development in accordance with Section 503(1.1) of the Pennsylvania
Municipalities Planning Code.
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.
LAND USE
The primary application employed in an area.
LIMESTONE
A rock that, by accumulation of organic remains, consists
mainly of calcium carbonate.
LINEAMENTS
Straight or gently curved, lengthy features frequently expressed
topographically as depressions or lines on the earth's surface. They
can be more easily observed at a height of 100 meters or more and
are usually found by researching aerial photographs or satellite photography.
They are usually located in areas of faulting or in dense jointing
along some rock stratigraphy.
MAIN STEM (MAIN CHANNEL)
Any stream segment or other runoff conveyance facility used
as a reach in the Spring Creek hydrologic model.
MINIMUM ALLOWABLE DISCHARGE
In relation to this chapter, the minimum rate that can be
discharged for any drainage area for design storm events up to and
including the ten-year event regardless of the modeled predevelopment
runoff estimate.
MUNICIPAL ENGINEER
A professional engineer licensed in the Commonwealth of Pennsylvania
and duly appointed by the municipality as their representative.
MUNICIPALITY
The Township of Halfmoon, Centre County, Pennsylvania.
OUTFALL
Point where water flows from a conduit, stream or drain.
OUTLET
Points of water disposal from a stream, river, lake, tidewater
or artificial drain.
PA DEP
Pennsylvania State Department of Environmental Protection.
PA DOT
Pennsylvania State Department of Transportation.
PEAK DISCHARGE
The maximum rate of stormwater runoff from a specific storm
event.
PERCOLATION RATE
The rate at which water moves through a soil profile. Percolation
rates are measured in units of time/length.
PIPE
A culvert, closed conduit, or similar structure (including
appurtenances) that conveys stormwater.
POINT DISCHARGE
The discharge from a pipe or channel that concentrates runoff
at a single area.
RECHARGE VOLUME
The volume of water that is required to be recharged from
developed sites.
REGISTERED PROFESSIONAL
An individual registered in and licensed by the State of
Pennsylvania, including, for the purposes of this chapter, land surveyors,
landscape architects, architects, and engineers.
REGULATED ACTIVITIES
Actions or proposed actions that have an impact on stormwater runoff and that are specified in §
200-5 of this chapter.
RETENTION BASIN
An impoundment in which stormwater is stored and not released
during the storm event. Stored water may be released from the basin
at some time after the end of the storm.
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 has a four-percent probability of occurring
in any given year.
RUNOFF
Any part of precipitation that flows over the land surface.
SAFE PASSAGE
The routing of peak runoff events, usually the one-hundred-year
design event, safely through a structure without failure of that structure.
SCOUR
Generally refers to the change in a channel configuration
provoked by sediment imbalance, due to natural or man-made causes,
between the supply and transport capacity of the channel.
SEDIMENT BASIN
A barrier, dam, retention or detention basin located and
designed to retain rock, sand, gravel, silt, or other material transported
by water.
SENSITIVE (WATER QUALITY) AREA
An area protected because development within that area could
potentially cause contamination of groundwater reservoirs. These sensitive
land areas are defined in Appendix B, Exhibit-1.
SHEET FLOW
Runoff that flows over the ground surface as a thin, even
layer, not concentrated in a channel.
SINKHOLE
A localized, gradual or rapid sinking of the land surface
to a variable depth, occurring in areas of carbonate bedrock; generally
characterized by a roughly circular outline, a distant breaking of
the ground surface and downward movement of soil into bedrock voids.
SPILLWAY
A depression in the embankment of a pond or basin which is
used to pass peak discharge greater than the maximum design storm
controlled by the pond.
STABILIZATION
The proper placing, grading and/or covering of soil, rock
or earth to ensure their resistance to erosion, sliding or other movement.
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 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, and infiltration structures.
STORMWATER MANAGEMENT PLAN
The documentation of the stormwater management system, if any, to be used for a given development site, the contents of which are established in §
200-23.
STRATA
Tabular or sheet-like mass, distinct layers of homogenous
or gradational sedimentary material (consolidated rock or unconsolidated
earth) of any thickness, visually separable from other layers above
and below by a discrete change in the character of the material deposited
or by a sharp physical break deposition or both.
STRATIGRAPHIC UNIT
A stratum or body of strata recognized as a unit in the classification
of the rocks of the earth's crust with respect to any specific rock
character, property, attribute or for any purpose such as description,
mapping, and correlation.
STRUCTURAL FILL
For the purposes of this chapter, shall imply any soil mass
that is compacted in lifts to some tested criteria (standard or modified
proctor) such as those under foundations or adjacent to retaining
walls. Areas that for several years after construction respond to
precipitation events similar to impervious areas.
SUBAREA
The smallest drainage unit of a watershed for which stormwater
management criteria have been established in the stormwater management
plan.
SWALE
A natural low-lying stretch of land or minor man-made conveyance
channel, which gathers or carries surface water runoff.
SWM
Stormwater management.
TOPOGRAPHY
The general configuration of a land surface or any part of
the earth's surface, including its relief and position of its natural
and man-made features. The natural or physical surface features of
a region, considered collectively as to its form.
UNDETAINED AREA
An area of a site that cannot be routed to a stormwater management
facility because of its location. Generally small areas around access
drives or below stormwater management facilities.
WATER QUALITY DEPTH
Depth of precipitation required to be used in computing the
water quality volume based on the percentage of imperviousness of
a site.
WATER QUALITY SENSITIVE (WQS) DEVELOPMENT
Land development projects that have a high potential to cause catastrophic loss to local water quality and could potentially threaten groundwater reservoirs. See §
200-14 for additional definition.
WATERSHED
The entire region or area drained by a river or other body
of water, whether natural or artificial, a drainage basin or subbasin.
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 and underground
water, or parts thereof, whether natural or artificial, within or
on the boundaries of this commonwealth.
WATER TABLE
Upper surface of a layer of saturated material in the soil.
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.