As used in this chapter, the following words
shall have the following meanings:
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 structures 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/or 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/OWNER
An applicant, owner and/or developer who has filed an application for approval to engage in any regulated activities as defined in §
187-4 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
the 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 beings
to overflow onto a floodplain.
BASE FLOOD ELEVATION (BFE)
The elevation shown on the Flood Insurance Rate Map (FIRM)
for Zones AE, AH, A1-30 that indicates the water surface elevation
resulting from a flood that has a one-percent or greater chance of
being equaled or exceeded in any given year. For Zone A, the BFE will
be that elevation established by the applicant with the approval of
the Township Engineer.
[Added 12-18-2018 by Ord.
No. 2018-11]
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 Stormwater Best Management Practices Manual (Draft-January, 2005)
or the latest revision may be referenced for specific BMP practices.
CHANNEL EROSION
The widening, deepening and headward cutting of small channels
and waterways, due to erosion of the stream embankments and channels.
CISTERN
A man-made underground reservoir or tank for storing groundwater
seeps or rainwater.
CONDUIT
A pipe used for water conveyance.
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 which does or may impound water or another
fluid or semifluid.
DEPARTMENT
Pennsylvania Department of Environmental Protection.
DESIGNEE
The agent of the Township of Falls involved with the administration,
technical 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 return period) 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 slow and 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.
DEVELOPER
A person, partnership, association, corporation or other
entity, or any responsible person therein or legally authorized to
act on behalf of the legal owner or equitable owner, that undertakes
or intends to undertake any regulated activity of this chapter.
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 and other similar facilities.
DRAINAGE EASEMENT
A right granted by a landowner to a grantee allowing the
use of private land for drainage and/or stormwater management purposes.
DRAINAGE PERMIT
A permit issued by the municipal Board of Supervisors after
the drainage plan has been approved. Said permit is issued prior to
or with the final municipal approval.
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 §
187-18.
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.
EASEMENT
An integral part of a BMP designed to drain flows greater
than the design flow.
EMERGENCY SPILLWAY
A device constructed as a channel or a pipe that will allow
passage of the excess stormwater accumulated in the stormwater retention
basin. This condition occurs because the original design discharge
devices would not remove the stormwater at a rate adequately that
the inflow would prevent gross overflow of the retained stormwater.
The emergency spillway devices, whether open channel or vertical riser
pipe or others, will be designed to transfer out of the basin at a
rate of flow that would prevent surcharging of the basin embankment.
EROSION
The movement of soil particles induced by natural forces
such as water, wind, ice and by land development by humans.
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, such as forested lands.
FEMA
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, stormwater management facilities and waters of the commonwealth.
FLOODPLAIN
A relatively flat or low land area which is subject to partial
or complete inundation from an adjoining or nearby stream, river or
watercourse; and/or any area subject to the unusual and rapid accumulation
of surface waters from any source.
[Amended 12-18-2018 by Ord. No. 2018-11]
FLOODWAY
The channel of a river or other watercourse and the adjacent
land areas that must be reserved in order to discharge the base flood
without cumulatively increasing the water surface elevation more than
one foot.
[Amended 12-18-2018 by Ord. No. 2018-11]
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, stormwater conveyance
system, or diversion ridge. The space is required as a safety margin
in a pond, detention basin or stormwater conveyance system.
[Amended 12-18-2018 by Ord. No. 2018-11]
GRADE
A slope, usually of a road, channel or natural ground, specified
in percent and shown on plans as specified herein.
GRASSED WATERWAY
A natural or constructed waterway, usually broad and shallow,
covered with erosion-resistant grasses, used to conduct surface water
from cropland.
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.
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
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 buildings; or
(2)
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.
C.
Development in accordance with § 503(1.1)
of the Pennsylvania 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 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
which is so slowly permeable that it effectively limits downward passage
of effluent.
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 waterbody from diffuse origins in
the watershed and does not result from discernible, confined or discrete
conveyances or origin.
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 Soil Conservation
Service, SCS, United States Department of Agriculture).
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 (for computational purposes).
OUTFALL
The point where water flows from a conduit, stream or drain.
OUTLET
Points of water disposal from a stream, river, lake, tidewater
or stormwater management facility.
PADEP
The Pennsylvania Department of Environmental Protection.
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
The use of impervious parking areas for temporary impoundment
of stormwater with controlled release rates during rainstorms.
PEAK DISCHARGE
The maximum rate of stormwater runoff from a specific storm
event.
PennDOT
The Pennsylvania Department of Transportation.
[Added 12-18-2018 by Ord.
No. 2018-11]
PIPE
A circular closed conduit, culvert 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 Pennsylvania 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.
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 Township are planned, conducted, or maintained.
RATIONAL FORMULA
A rainfall-runoff relationship used to estimate peak flow
or discharge flow.
RECHARGE AREA
Undisturbed surface area or depression where stormwater collects
and a portion of which infiltrates and replenishes the underground
and ground water.
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 suit the as-built conditional
and subsequently provided by the Engineer to the client. The Engineer
takes the contractor's as-built, reviews it 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
The construction, alteration, or improvement performed on
sites where existing land use is commercial industrial, institutional,
or multifamily residential.
[Amended 12-18-2018 by Ord. No. 2018-11]
REDEVELOPMENT ACTIVITIES
Activities of development that meet the definition of redevelopment and are approved by the Township Engineer to proceed in accordance with §
187-18.
[Added 12-18-2018 by Ord.
No. 2018-11]
REGULATED ACTIVITIES
Actions or proposed actions that have an impact on stormwater runoff and that are specified in §
187-4 of 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 Township'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 RATES
The percentage of predevelopment peak rate of runoff from
a site or subarea to which the postdevelopment 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 this basin
at some time after the end of the storm.
RETURN PERIOD
The average interval (i.e., frequency), 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 that would
be expected to recur on the average 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
sections, 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.
SALDO
Subdivision and Land Development Ordinance.
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.
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 runoff curve number. "Curve number" is a parameter that
relates soil types and land uses/covers conditions.
SOIL GROUPS, HYDROLOGIC
A classification of soils by the NRCS into four runoff categories.
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.
SPILLWAY
A conveyance that is used to pass the peak discharge of the
maximum design storm controlled by the stormwater facility and is
used to discharge flow when the design storage capacity is exceeded.
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."
STATE WATER QUALITY REQUIREMENTS
As defined under state regulations, protection of designated
and existing uses (see 25 Pennsylvania 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 streambank, streambed, and structural integrity of the waterway
to prevent these impacts.
STORM SEWER
A system of pipes and/or other conduits which carries intercepted
surface runoff, street water and other wash waters or drainage, but
excludes domestic sewage and industrial wastes.
STORMWATER
Drainage runoff from the surface of the land resulting from
precipitation or snow or ice melt.
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, forebays, detention and retention basins, open channels,
storm sewers, pipes, spillways, risers, inlets, outlets, infiltration
structures and outfalls.
STORMWATER MANAGEMENT SITE PLAN (SMSP)
The plan prepared by the applicant/owner and/or his representative
indicating how stormwater runoff will be managed at the particular
site of interest in accordance with 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, 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
dwellings, shall be exempt.
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 conveys 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,
shallow concentrated time and flow time in pipes or channels, if any.
TO GRADE
To create the surface of a road bed, top of embankment or
bottom of excavation.
WATERCOURSE
A stream of water; river; brook; creek; or a channel or ditch
for water, whether natural or man-made.
WATERS OF THE COMMONWEALTH
Any and all rivers, streams, creeks, rivulets, 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 QUALITY VOLUME
Total volume of runoff delivered to the inlet of a water
quality BMP and is equal to runoff volume generated from a two-year-return-period
storm event.
WATERSHED
Region or area drained by a river, watercourse, or other
body of water, whether natural or artificial.
WELLHEAD
1) A structure built over a well; 2) 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
Areas that are inundated or saturated by surface water or
groundwater at a frequency or 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 and similar areas.