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 human activity and natural processes at 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, tillage, land clearing, plowing,
disking, harrowing, planting, harvesting crops, or pasturing and raising
of livestock 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;
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
for approval to engage in any regulated activities at a project site
within the municipality.
BEST MANAGEMENT PRACTICES (BMPs)
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: "nonstructural"
or "structural." Nonstructural BMPs are measures referred to as "operational"
and/or behavior-related practices that attempt to minimize the contact
of pollutants with stormwater runoff whereas structural BMPs are measures
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.
CHANNEL EROSION
The widening, deepening and headward cutting of small channels
and waterways due to erosion caused by moderate to large floods.
CISTERN
An underground reservoir or tank used for storing rainwater.
CONSERVATION DISTRICT
The Clarion County Conservation District. The Clarion County
Conservation District has the authority under a delegation agreement
executed with the Department of Environmental Protection to administer
and enforce all or a portion of the regulations promulgated under
25 Pa. Code Chapter 102.
CULVERT
A structure with appurtenant works that carries a stream
and/or stormwater runoff 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.
DESIGN STORM
The magnitude and temporal distribution of precipitation
from a storm event measured in probability of occurrence (e.g., a
twenty-five-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 this municipality 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.
DETENTION VOLUME
The volume of runoff that is captured and released into 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 SITE (SITE)
The specific tract of land for which a regulated activity
is proposed. Also see "project site."
DISTURBED AREA
An 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 convey 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, drainage or conveyance
purposes.
DRAINAGEWAY
Any natural or artificial watercourse, trench, ditch, pipe,
swale, channel or similar depression into which surface water flows.
EARTH DISTURBANCE ACTIVITY
A construction or other human activity which disturbs the
surface of the 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 or similar activity.
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 satisfies Pennsylvania
Code Title 25, Environmental Protection, Chapter 93, Water Quality
Standards, § 93.4b(b) (relating to anti-degradation).
EXISTING CONDITIONS
The initial condition of a project site prior to the proposed
construction. If the initial condition of the site is undeveloped
land and not forested, the land use shall be considered as "meadow"
unless the natural land cover is documented to generate lower curve
numbers.
FEMA
The 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 the commonwealth.
FLOOD-FRINGE
The remaining portions of the one-hundred-year floodplain
outside of the floodway boundary.
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
- mapped as being a special flood hazard area. Included are lands
adjoining a river or stream that have been or may 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 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.
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 tank, pond or basin.
GRADE
A slope, usually of a road, channel or natural ground, specified
in percent and shown on plans as specified herein.
(TO) GRADE
To finish the surface of a roadbed, top of embankment or
bottom of excavation.
HIGH QUALITY WATERS
Surface water 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).
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 one of four HSG (A, B, C and D) according to their
minimum infiltration rate, which is obtained for bare soil after prolonged
wetting. The Natural Resource Conservation Service (NRCS) of the United
States 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 interest may be identified from a soil survey
report from the local NRCS office or the County Conservation District.
IMPERVIOUS SURFACE (IMPERVIOUS AREA)
A surface that prevents the infiltration of water into the
ground. Impervious surface (or area) includes, but is not limited
to, roofs, additional indoor living spaces, patios, garages, storage
sheds and similar structures, paved parking or driveway areas, and
any new paved streets and sidewalks.
IMPOUNDMENT
A retention or detention basin designed to retain stormwater
runoff and release it at a controlled rate.
INFILTRATION STRUCTURES
A structure designed to direct runoff into the ground (e.g.,
french drains, seepage pits, seepage trench, etc.).
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.
LAND DEVELOPMENT (DEVELOPMENT)
A.
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;
B.
Any subdivision of land; or
C.
Development in accordance with Section 503(1.1) of the Pennsylvania
Municipalities Planning Code.
LOW-IMPACT DEVELOPMENT (LID)
An approach to land development that uses various land planning
and design practices and technologies to simultaneously conserve and
protect natural resource systems and reduce infrastructure costs.
LID still allows land to be developed, but in a cost-effective manner
that helps mitigate potential environmental impacts.
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.
NOAA ATLAS 14
Precipitation-Frequency Atlas of the United States, Atlas
14, Volume 2, United States Department of Commerce, National Oceanic
and Atmospheric Administration, National Weather Service, Hydrometeorological
Design Studies Center, Silver Spring, Maryland (2004). NOAA's
Atlas 14 can be accessed at Internet address: http://hdsc.nws.noaa.gov/hdsc/pfds/.
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.
NRCS
Natural Resource Conservation Service [previously Soil Conservation
Service (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
not under pressure.
OUTFALL
A.
Point where water flows from a conduit, stream or drain.
B.
"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.
PADEP
The Pennsylvania Department of Environmental Protection.
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.
PERSON
An individual, partnership, public or private association
or corporation, or a governmental unit, public utility or any other
legal entity whatsoever which is recognized by law as the subject
of rights and duties.
PIPE
A culvert, closed conduit, or similar structure (including
appurtenances) that conveys stormwater.
POINT SOURCE
Any discernible, confined, or 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.
PROBABLE MAXIMUM FLOOD (PMF)
The flood that may be expected from the most severe combination
of critical meteorological and hydrologic conditions that are reasonably
possible in any area. The PMF is derived from the probable maximum
precipitation (PMP) as determined on the basis of data obtained from
the National Oceanographic and Atmospheric Administration (NOAA).
PROJECT SITE
The specific area of land where any regulated activities
in the municipality are planned, conducted or maintained.
REDEVELOPMENT
Earth disturbance activities on land which has previously
been developed.
REGULATED ACTIVITIES
Any activities that involve the alteration or development
of land in a manner that may affect stormwater runoff.
RELEASE RATE
The percentage of predevelopment peak rate of runoff from
a site or subwatershed area to which the post-development peak rate
of runoff must be reduced to protect downstream areas.
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.
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 once
every 25 years or, stated in another way, the probability of a twenty-five-year
storm occurring in any one given year is 0.04 (i.e., a four-percent
chance).
RIPARIAN BUFFER
A vegetated area bordering perennial and intermittent streams
and wetlands, that serves as a protective filter to help protect streams
and wetlands from the impacts of adjacent land uses.
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
Road maintenance activities that do not disturb the subbase
of a paved road (such as milling and overlays) are not considered
earth disturbance activities.
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.
RUNOFF CAPTURE VOLUME
The volume of runoff that is captured (retained) and not
released into surface waters of the commonwealth during or after a
storm event.
SEDIMENT
Soils or other materials transported by surface water as
a product of erosion.
SEDIMENT BASIN
A barrier, dam, retention or detention basin located and
designed to retain rock, sand, gravel, silt or other material transported
by stormwater runoff.
SEDIMENT POLLUTION
The placement, discharge or any other introduction of sediment
into waters of the commonwealth occurring from the failure to properly
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 ground.
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.
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 curve number (CN).
SPILLWAY (EMERGENCY)
A depression in the embankment of a pond or basin, or other
overflow structure, that is used to pass peak discharges greater than
the maximum design storm controlled by the pond or basin.
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.
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 also "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
Runoff from the surface of the land resulting from precipitation,
snow or ice melt.
STORMWATER HOT SPOT
A land use or activity that generates higher concentrations
of hydrocarbons, trace metals, or toxicants than are found in typical
stormwater runoff.
STORMWATER MANAGEMENT FACILITIES
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 facilities.
STORMWATER MANAGEMENT PLAN
The Clarion County Stormwater Management Plan for managing
stormwater runoff in Clarion County as required by the Act of October
4, 1978, P.L. 864, (Act 167) and known as the "Storm Water Management
Act."
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.
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 (Pennsylvania Municipalities Planning
Code, Act of July 31, 1968, P.L. 805, No. 247).
SUBWATERSHED AREA
The smallest drainage unit of a watershed for which stormwater
management criteria has been established in the stormwater management
plan.
SWALE
A low-lying stretch of land that 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.
USDA
The United States Department of Agriculture.
WATERCOURSE
A channel or conveyance of surface water, such as a stream
or creek, having defined bed and banks, whether natural or artificial,
with perennial or intermittent flow.
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 the Commonwealth of Pennsylvania.
WATERSHED
Area drained by a river, watercourse or other surface water,
whether natural or artificial.
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 and have identified
hydric soils, including swamps, marshes, bogs and similar areas. (The
term includes but is not limited to wetland areas listed in the State
Water Plan, the United States Forest Service Wetlands Inventory of
Pennsylvania, the Pennsylvania Coastal Zone Management Plan and a
wetland area designated by a river basin commission. This definition
is used by the United States Environmental Protection Agency and the
United States Army Corps of Engineers.)