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 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.
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 applicant who has filed an application for approval
to engage in any regulated activities as defined in 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 the same,
are turned over to the Borough's designee 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 management facility 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. The PA Handbook of
BMPs for Developing Areas and the Maryland Stormwater Design Manual may be
referenced for specific BMP practices.
BOROUGH
Morrisville Borough, Bucks County, Pennsylvania.
CHANNEL EROSION
The widening, deepening, and headward cutting of small channels and
waterways caused by moderate to large floods.
CISTERN
An underground reservoir or tank for storing rainwater.
CULVERT
A structure with appurtenant works which carries a stream 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
that does or may impound water or another fluid or semifluid.
DEP
Pennsylvania Department of Environmental Protection.
DEPARTMENT
Pennsylvania Department of Environmental Protection.
DESIGNEE
The agent of the Borough responsible for the administration, review,
or enforcement of any provisions of this chapter by contract or memorandum
of understanding.
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.
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
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 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.
DRAINAGE PERMIT
A permit issued by the Borough after the drainage plan has been approved.
Said permit is issued prior to or with the final Borough approval.
DRAINAGE PLAN
The documentation of the stormwater management system, to be used
for a given development site, the contents of which are established in this
chapter.
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 movement of soil particles by the action of water, wind, ice,
or other natural forces.
ERSAM
Existing Resource and Site Analysis Map.
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 construction.
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" values.
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 as a special flood hazard area on the applicable National
Flood Insurance Program Flood Insurance Rate Map (FIRM) prepared by the Federal
Emergency Management Agency (FEMA). Also included are areas that comprise
Group 13 Soils, as listed in Appendix A of the DEP Technical Manual for Sewage
Enforcement Officers (as amended or replaced from time to time by DEP).
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 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 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
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 conduct surface water.
HEC-HMS
The U.S. Army Corps of Engineers, Hydrologic Engineering Center (HEC)
- Hydrologic Modeling System (HMS) adapted to the Delaware River South Creek
watershed.
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, baseflow, 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.
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
A surface that prevents the percolation of water into the ground
such as building rooftops, pavement, sidewalks, driveways and compacted earth
or turf.
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 in 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
The passing of stormwater through the soil from the surface.
INFILTRATION STRUCTURES
A structure designed to direct runoff into the ground (e.g., french
drains, seepage pits, seepage trench).
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
(1)
The improvement of one lot or two or more contiguous lots, tracts, or
parcels of land for any purpose involving: (i) a group of two or more residential
or nonresidential buildings, whether initially or cumulatively, or a single
nonresidential building on a lot or lots regardless of the number of occupants
or tenure; or (ii) 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)
Development in accordance with Section 503(1.1) of the Pennsylvania
Municipalities Planning Code Act of 1968 (Act 247).
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 it effectively limits downward passage of effluent.
MAIN STEM (MAIN CHANNEL)
Any stream segment or other runoff conveyance facility used as a
reach in the Delaware River South Creek 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 body of water from diffuse origins in the
watershed and does not result from confined or discrete conveyances.
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 Resources Conservation Service (previously Soil Conservation
Service).
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 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
as of the date of the original Delaware River South Creek Stormwater Ordinance
adoption.
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 Delaware
River South Creek 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 meteorological 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).
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.
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 area of land where any regulated activities in the Borough
are planned, conducted or maintained.
RECHARGE AREA
Undisturbed surface area or depression where stormwater collects,
and a portion of which infiltrates and replenishes the underground and groundwater.
RECONSTRUCTION
The process by which existing developed area is adaptively reused,
rehabilitated, restored, renovated, and/or expanded. The development relies
on existing infrastructure and does not require an extension of water, sewer,
or other public utilities.
RECORD DRAWINGS
Original documents revised to reflect the as-built conditions.
REDEVELOPMENT
The construction, alteration, or improvement exceeding 5,000 square
feet of land disturbance performed 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
and that are specified in this chapter.
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 of
the planned runoff. This includes earth disturbance on any portion of, part,
or during any stage of, a larger common plan of development.
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.
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 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.
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
Chapter
390, Subdivision and Land Development, of this Code.
SEDIMENTATION
The process by which mineral or organic matter is accumulated or
deposited by the movement of water.
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 the DEP Erosion and Sediment Pollution Control Program
Manual.
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
A conveyance that is used to pass the peak discharge of the maximum
design storm controlled by the stormwater facility.
STATE WATER QUALITY REQUIREMENTS
As defined under state regulations, protection of designated and
existing uses (see 25 Pa. Code Chapters 93 and 96), including:
(1)
Each stream segment in Pennsylvania has a "designated use," such as
"cold water fishery" or "potable water supply," which are 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. 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.
(3)
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 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, streambed 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 excludes domestic sewage and industrial
wastes.
STORMWATER
The total amount of 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.
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 stormwater runoff in the Delaware River South
Watershed adopted by Bucks County as required by the Act of October 4, 1978,
P.L. 864 (Act 167), and known as the "Delaware River South 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 BUFFER
The land area adjacent to each side of a stream, essential to maintaining
water quality measured 150 feet from the top of the bank.
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
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 of 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 proposes into parcels of
more than ten acres, not involving any new street or easement of access or
any residential dwelling, shall be exempted.
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 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.
WATERCOURSE
A river, brook, creek, or a channel or ditch for water, whether natural
or man-made with perennial or intermittent flow.
WATERSHED
Region or area drained by a river, watercourse or other body of water,
whether natural or artificial.
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
A structure built over a well, or the source of water for a well.
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 towards and reach
the water source.
WETLAND
Those areas that are inundated or saturated by surface 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.