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
The work of producing crops and raising livestock, including
tillage, plowing, disking, harrowing, pasturing and installation of
conservation measures. For purposes of regulation by this chapter,
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 person who has filed an application for approval to engage in any regulated activities as defined in §
425-4 of this chapter.
AS-BUILT DRAWINGS
Those 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, or a copy of
same, are turned over to the Engineer at the completion of the project.
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.
BIORETENTION
A stormwater retention area which utilizes woody and herbaceous
plants and soils to remove pollutants before infiltration occurs.
BMP (BEST MANAGEMENT PRACTICE)
Stormwater structures, facilities and techniques to control,
maintain or improve the quantity and quality of surface runoff and
groundwater recharge.
BUFFER
The area of land immediately adjacent to any wetland, lake,
pond, vernal pond, or stream, measured perpendicular to and horizontally
from the delineated edge of the wetland, lake, pond, or vernal pond,
or the top-of-bank on both sides of a stream.
CHANNEL EROSION
The widening, deepening, and headward cutting of small channels
and waterways, caused by stormwater runoff or bankfull flows.
CISTERN
An underground reservoir or tank for storing rainwater.
CONSUMPTIVE WATER USE
That part of water removed from the immediate water environment
not available for other purposes, such as water supply, maintenance
of stream flows, water quality, fisheries and recreation, as opposed
to water that is used nonconsumptively, which is returned to surface
water, where practicable, and groundwater.
CULVERT
A structure with appurtenant works, which carries 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.
DEPARTMENT
The Pennsylvania Department of Environmental Protection.
DESIGN PROFESSIONAL (QUALIFIED)
A Pennsylvania-registered professional engineer, registered
landscape architect or a registered professional land surveyor trained
to develop stormwater management plans.
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 the Monroe County Planning Commission, Monroe
County Conservation District 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 DISTRICT
Those subareas in which some type of detention is required
to meet the plan requirements and the goals of Act 167.
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.
DISTURBED AREAS
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 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 channels, swales, pipes, conduits, culverts,
storm sewers, etc.
DRAINAGE EASEMENT
A right granted by a grantor to a grantee, allowing the use
of private land for stormwater management purposes.
DRAINAGE PERMIT
A permit issued by the municipal governing body after the
drainage plan has been approved.
DRAINAGE 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 §
425-21.
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, 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 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 antidegradation).
EXISTING CONDITIONS
The initial condition of a project site prior to the proposed
alteration. 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 lower curve numbers or Rational "C" value.
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 Department of Housing and
Urban Development, Federal Insurance Administration Flood Hazard Boundary
- Mapped as being a special flood hazard area.
FLOODWAY
The channel of the watercourse and those portions of the
adjoining floodplains which are reasonable 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 forestland
with no change of land use proposed. 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 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.
GRASSED WATERWAY
A natural or constructed waterway, usually broad and shallow,
covered with erosion-resistant grasses, used to convey surface water.
GROUNDWATER RECHARGE
Replenishment of existing natural underground water supplies
without degrading groundwater quality.
HEC-HMS
The U.S. Army Corps of Engineers, Hydrologic Engineering
Center (HEC) - Hydrologic Modeling System (HMS) computer program.
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).
HYDROLOGIC REGIME (NATURAL)
The hydrologic cycle or balance that sustains quality and
quantity of stormwater, base flow, storage, and groundwater supplies
under natural conditions.
HYDROLOGIC SOIL GROUP
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.
IMPERVIOUS SURFACE
A surface that prevents the percolation of water into the
ground, such as rooftops, pavement, sidewalks, driveways, gravel drives,
roads and parking, and compacted fill, earth or turf to be used as
such.
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
For stormwater to pass through the soil from the surface.
INFILTRATION STRUCTURES
A structure designed to direct runoff into the underground
water (e.g., French drains, seepage pits, seepage trench).
INLET
The upstream end of any structure through which water may
flow.
LAND DEVELOPMENT
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
strata which 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 molding.
B.
A rock with open joints, fractures 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, which is
so slowly permeable that it effectively limits downward passage of
water.
LOT
A part of a subdivision or a parcel of land used as a building
site or intended to be used for building purposes, whether immediate
or future, which would not be further subdivided. Whenever a lot is
used for a multiple-family dwelling or for commercial, institutional
or industrial purposes, the lot shall be deemed to have been subdivided
into an equivalent number of single-family residential lots as determined
by estimated sewage flows.
MAIN STEM (MAIN CHANNEL)
Any stream segment or other runoff conveyance facility used
as a reach in the Brodhead/McMichaels 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.
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.
NONSTRUCTURAL 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.
NRCS
Natural Resource Conservation Service (previously "SCS").
OPEN CHANNEL
A drainage element in which stormwater flows within 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 where water flows from a conduit, stream, or drain.
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 existing as of the date of municipal adoption of the original
Brodhead Creek Ordinance.
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.
PENN STATE RUNOFF MODEL (CALIBRATED)
The computer-based hydrologic modeling technique adapted
to the Brodhead/McMichaels watershed for the Act 167 Plan. The model
has been calibrated to reflect actual recorded flow values by adjoining
key model input parameters.
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 based on data obtained from the
National Oceanographic and Atmospheric Administration (NOAA).
PRACTICABLE ALTERNATIVE
An alternative that is available and capable of being done
after taking into consideration cost, existing technology and logistics
in light of overall project purposes.
PRETREATMENT
Techniques employed in structural and nonstructural stormwater BMPs to provide storage or filtering to help trap coarse materials and other pollutants before they enter the system, but not necessarily meet the water quality volume requirements of §
425-12.
RECHARGE AREA
Undisturbed surface area or depression where stormwater collects,
and a portion of which infiltrates and replenishes the underground
water and groundwater.
RECORD DRAWINGS
Original documents revised to suit the as-built conditions
and subsequently provided by the Engineer to the client. The Engineer
takes the contractor's as-builts, reviews them in detail with 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 construction, alteration, or improvement exceeding 5,000
square feet of impervious surface on sites where existing land use
is commercial, industrial, institutional, or multifamily residential.
REGULATED ACTIVITIES
Actions or proposed actions that have an impact on stormwater runoff quality and quantity and that are specified in §
425-4 of this chapter.
RELEASE RATE
The percentage of existing conditions 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 structure in which stormwater is stored and not released
during the storm event. Retention basins do not have an outlet other
than recharge and must infiltrate stored water in no more than four
days.
RETURN PERIOD
The average interval, in years, within which a storm event
of a given magnitude can be expected to recur.
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.
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.
SALDO
Subdivision and Land Development Ordinance.
SEDIMENT BASIN
A barrier, dam, retention or detention basin located and
designed 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.
SEDIMENTATION
The process by which mineral or organic matter is accumulated
or deposited by the movement of water or air.
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.
SHEET FLOW
Runoff that flows over the ground surface as a thin, even
layer.
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
A conveyance that is used to pass the peak discharge of the
maximum design storm controlled by the stormwater facility.
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 excludes domestic sewage
and industrial wastes.
STORMWATER
The surface runoff generated by precipitation reaching the
ground surface.
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 and quantity. 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 plan for managing those land use activities that will
influence stormwater runoff quality and quantity and that would impact
the Brodhead/McMichaels Watershed adopted by Monroe County and Pike
County as required by the Act of October 4, 1978, P.L. 864, (Act 167),
and known as the "Brodhead/McMichaels Watershed Act 167 Stormwater
Management Plan."
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 according to this chapter.
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.
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.
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.
VERNAL POND
An isolated, contained basin depression that holds water
for at least two months in the spring and summer, critical to several
amphibian, reptile and invertebrate species. It also provides important
storage for stormwater runoff and spring snowmelt that would otherwise
contribute to downstream flooding. A vernal pond is typically no bigger
than 300 feet long and 120 feet wide and is often much smaller.
WATERCOURSE
A channel or conveyance of surface water having defined bed
and banks, whether natural or artificial, with perennial or intermittent
flow.
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.
WELLHEAD
The point at which a groundwater well bore hole meets the
surface of the ground.
WELLHEAD PROTECTION AREA
The surface and subsurface area surrounding a water supply
well, well field, spring or infiltration gallery supplying a public
water system, through which contaminants are reasonably likely to
move toward and reach the water source.
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, fens, and similar areas.