For the purposes of this chapter, certain terms and words used
herein shall be interpreted as follows:
A.
Words used in the present tense include the future tense; the singular
number includes the plural, and the plural number includes the singular;
words of masculine gender include feminine gender; and words of feminine
gender include masculine gender.
B.
The word "includes" or "including" shall not limit the term to the
specific example, but is intended to extend its meaning to all other
instances of like kind and character.
C.
The word "person" includes an individual, firm, association, organization,
partnership, trust, company, corporation, unit of government, or any
other similar entity.
D.
The words "shall" and "must" are mandatory; the words "may" and "should"
are permissive.
E.
The words "used" or "occupied" include the words "intended, designed,
maintained, or arranged to be used, occupied or maintained."
As used in this chapter, the following terms shall have the
meanings indicated:
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.
Activities associated with agriculture such as agricultural
cultivation, agricultural operation, and animal heavy use areas. This
includes the work of producing crops including 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.
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 as the result of changing the land cover
including the water, vegetation and bare soil.
A landowner, developer or other person who has filed an application for approval to engage in any regulated activity defined in § 242-5 of this chapter.
Engineering or site drawings 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 documents, or a copy of same, are turned over to
the Township Engineer at the completion of the project.
The channel at the top-of-bank, or point from where water
begins to overflow onto a floodplain.
Portion of stream discharge derived from groundwater; the
sustained discharge that does not result from direct runoff or from
water diversions, reservoir releases, piped discharges, or other human
activities.
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:
"structural" or "nonstructural." In this chapter, nonstructural BMPs
or measures refer to operational and/or behavior-related practices
that attempt to minimize the contact of pollutants with stormwater
runoff whereas structural BMPs or measures are those 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.
A stormwater retention area that utilizes woody and herbaceous
plants and soils to remove pollutants before infiltration occurs.
An open drainage feature through which stormwater flows.
Channels include, but shall not be limited to, natural and man-made
watercourses, swales, streams, ditches, canals, and pipes that convey
continuously or periodically flowing water.
An underground reservoir or tank for storing rainwater.
The Montgomery County Conservation District.
A structure with its appurtenant works, which carries water
under or through an embankment or fill.
Value used in the Soil Cover Complex Method. It is a measure
of the percentage of precipitation which is expected to run off from
the watershed and is a function of the soil, vegetative cover, and
tillage method.
A man-made barrier, together with its appurtenant works,
constructed for the purpose of impounding or storing water or another
fluid or semifluid. A dam may include a refuse bank, fill or structure
for highway, railroad or other purposes which impounds or may impound
water or another fluid or semifluid.
The Pennsylvania Department of Environmental Protection (PADEP).
The agent of the Montgomery County, Montgomery County Conservation
District, and/or agent of Hatfield Township involved with the administration,
review, or enforcement of any provisions of this chapter by contract
or memorandum of understanding.
A Pennsylvania registered professional engineer, registered
landscape architect or registered professional land surveyor trained
to develop stormwater management plans.
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. Also see "return
period."
An impoundment designed to collect and retard stormwater
runoff by temporarily storing the runoff and releasing it at a predetermined
rate. Detention basins are designed to drain completely soon after
a rainfall event and become dry until the next rainfall event.
A person that seeks to undertake a land development, subdivision
or regulated activity.
Any human-induced change to improved or unimproved real estate,
whether public or private, including but not limited to land development,
construction, installation, or expansion of a building or other structure,
land division, street construction, drilling, and site alteration
such as embankments, dredging, grubbing, grading, paving, parking
or storage facilities, excavation, filling, stockpiling, or clearing.
As used in this chapter, development encompasses both new development
and redevelopment.
The specific tract or parcel of land where any regulated
activity is planned, conducted or maintained.
(verb) To release water from a project, site, aquifer, drainage
basin or other point of interest. (noun) The rate and volume of flow
of water such as in a stream, generally expressed in cubic feet per
second. See also "peak discharge."
The point of discharge for a stormwater facility.
An impervious or impermeable surface that is disconnected from any stormwater drainage or conveyance system and is redirected or directed to a pervious area, which allows for infiltration, filtration, and increased time of concentration as specified in Appendix F, Disconnected Impervious Area.[1]
Unstabilized land area where an earth disturbance activity
is occurring or has occurred.
A man-made waterway constructed for irrigation or stormwater
conveyance purposes.
A right granted by a landowner to a grantee, allowing the
use of private land for stormwater management purposes.
A permit issued by Hatfield Township after the SWM site plan
has been approved.
A construction or other human activity that 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, building construction and the moving,
depositing, stockpiling, or storing of soil, rock or earth materials.
Activity involving earth disturbance is subject to regulation under
25 Pa. Code 92, 25 Pa. Code 102, or the Clean Streams Law.[2]
A conveyance area that is used to pass peak discharge greater
than the maximum design storm controlled by the stormwater facility.
A structure or activity that changes, expands or diminishes
the course, current or cross section of a watercourse, floodway or
body of water.
The process by which the surface of the land, including water/stream
channels, is worn away by water, wind, or chemical action.
A site-specific plan identifying BMPs to minimize accelerated
erosion and sedimentation. For agricultural plowing or tilling activities,
the erosion and sediment control plan is that portion of a conservation
plan identifying BMPs to minimize accelerated erosion and sedimentation.
Surface waters of high quality which satisfy Pennsylvania
Code Title 25 Environmental Protection, Chapter 93, Water Quality
Standards, § 93.4b(b) (relating to antidegradation).
The initial condition of a project site prior to the proposed
alteration.
Undisturbed surface area or depression where stormwater collects
and a portion of which infiltrates and replenishes the groundwater.
A temporary condition of partial or complete inundation of
land areas from the overflow of streams, rivers, and other waters
of the commonwealth.
Any land area susceptible to inundation by water from any
natural source or as delineated by applicable Department of Housing
and Urban Development, Federal Insurance Administration Flood Hazard
Boundary Map as being a special flood hazard area.
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
a designated height.
Planning and associated 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, and reforestation.
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.
Elected municipal officials of Hatfield Township.
(noun) A slope, usually of a road, channel or natural ground
specified in percent and shown on plans as specified herein. (verb)
To finish the surface of a roadbed, the top of an embankment, or the
bottom of excavation.
Water beneath the earth's surface that supplies wells
and springs, and is often between saturated soil and rock.
The replenishment of existing natural underground water supplies
from rain or overland flow.
The United States Army Corps of Engineers, Hydrologic Engineering
Center (HEC), Hydrologic Modeling System (HMS). This model was used
to model the Neshaminy Creek watershed during the Act 167 Plan development
and was the basis for the standards and criteria of this chapter.
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).
An area where land use or activity generates highly contaminated runoff, with concentrations of pollutants in excess of those typically found in stormwater. Typical pollutant loadings in stormwater may be found in Chapter 8, Section 6, of the Pennsylvania Stormwater Best Management Practices Manual, Pennsylvania Department of Environmental Protection (PADEP) No. 363-0300-002 (2006). Additional information concerning hot spots may be found in § 242-17 of this chapter.
A graph representing the discharge of water versus time for
a selected point in the drainage system.
The hydrologic cycle or balance that sustains quality and
quantity of stormwater, base flow, storage, and groundwater supplies
under natural conditions.
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.
Those surfaces which are covered in any way so as not to
allow the ground beneath to absorb water at a natural rate, including,
but not limited to, buildings, walks, roofs, swimming pools, man-made
ponds, and paved or stoned areas.
A retention or detention basin designed to retain stormwater
runoff and release it at a controlled rate.
Movement of surface water into the soil, where it is absorbed
by plant roots, evaporated into the atmosphere, or percolated downward
to recharge groundwater.
A structure designed to direct runoff into the underground
water (e.g., french drains, seepage pits, or seepage trenches).
The value used to calculate the volume or peak rate of runoff
in the Soil Cover Complex Method. It represents the depth of rain
retained on vegetation plus the depth of rain stored on the soil surface
plus the depth of rain infiltrated prior to the start of runoff.
The upstream end of any structure through which water may
flow.
A stream that flows only part of the time. Flow generally
occurs for several weeks or months in response to seasonal precipitation
or groundwater discharge.
A type of topography or landscape characterized by surface
depressions, sinkholes, rock pinnacles/uneven bedrock surface, underground
drainage, and caves. Karst is formed on carbonate rocks, such as limestone
or dolomite.
Any of the following activities:
The improvement of one lot or two or more contiguous lots, tracts,
or parcels of land for any purpose involving:
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
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;
A subdivision of land;
Development in accordance with Section 503(1.1) of the Pennsylvania
Municipalities Planning Code.[3]
Soil horizon or condition in the soil profile or underlying
strata that includes one of the following:
A seasonal high-water table, whether perched or regional, determined
by the direct observation of the water table or indicated by soil
mottling.
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.
A rock formation, other stratum or soil condition that is slowly
permeable that it effectively limits downward passage of effluent.
A designated parcel, tract, or area of land established by
a plat or otherwise as permitted by law and to be used, developed
or built upon as a unit.
Practices that will minimize proposed conditions runoff rates
and volumes, which will minimize needs for artificial conveyance and
storage facilities.
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.
A professional engineer licensed as such in the Commonwealth
of Pennsylvania, duly appointed as the engineer for Hatfield Township.
Hatfield Township, Montgomery County, Pennsylvania.
See "hydrologic regime."
Pollution that enters a water body from diffuse origins in
the watershed and does not result from discernible, confined, or discrete
conveyances.
Water flowing in stormwater collection facilities, such as
pipes or swales, which is not the result of a rainfall event or snowmelt.
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.
National Pollutant Discharge Elimination System, the federal
government's system for issuance of permits under the Clean Water
Act, which is delegated to PADEP in Pennsylvania.
Natural Resource Conservation Service (previously Soil Conservation
Service).
"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.
Points of water disposal to a stream, river, lake, tidewater
or artificial drain.
The maximum rate of stormwater runoff from a specific storm
event.
The computer-based hydrologic model developed at the Pennsylvania
State University.
A stream which contains water at all times except during
extreme drought.
A surface that allows the infiltration of water into the
ground.
A culvert, closed conduit, or similar structure (including
appurtenances) that conveys stormwater.
The Planning Commission of Hatfield Township.
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.
Period after construction during which disturbed areas are
stabilized, stormwater controls are in place and functioning and all
proposed improvements in the approved land development plan are completed.
See "existing condition."
Techniques employed in stormwater BMPs to provide storage
or filtering to trap coarse materials and other pollutants before
they enter the system, but not necessarily designed to meet the volume
requirements of this chapter.
The specific area of land where any regulated activities
in the municipality are planned, conducted or maintained.
Any person licensed by the Pennsylvania Department of State
or otherwise qualified by law to perform the work required by this
chapter.
A rainfall-runoff relation used to estimate peak flow.
The replenishment of groundwater through the infiltration
of rainfall, other surface waters, or land application of water or
treated wastewater.
Original documents revised to suit the as-built conditions
and subsequently provided by the engineer to the client. The engineer
reviews the contractor's as-built drawings against 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. Record drawings are not the
same as record plans submitted for recording with the county in accordance
with the Pennsylvania Municipalities Planning Code (Act 247).[4]
Any development that requires demolition or removal of existing
structures or impervious surfaces at a site and replacement with new
impervious surfaces. Maintenance activities such as top-layer grinding
and repaving are not considered to be redevelopment. Interior remodeling
projects and tenant improvements are also not considered to be redevelopment.
Utility trenches in streets are not considered redevelopment unless
more than 50% of the street width including shoulders is removed and
repaved.
Any earth disturbance activities or any activities that involve
the alteration or development of land in a manner that may affect
stormwater runoff.
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.
Replacement of the impervious surface that does not involve
reconstruction of an existing paved (impervious) surface.
Reconstruction of and full replacement of an existing paved
(impervious) surface.
A structure in which stormwater is stored and not released
during the storm event. Retention basins are designed for infiltration
purposes, and do not have an outlet. The retention basin must infiltrate
stored water in four days or less.
The volume of runoff that is captured and not released directly
into the surface waters of the commonwealth during or after a storm
event.
The probability an event will occur in any given year. Typically
displayed as a whole number, e.g., twenty-five-year event, and represents
the inverse of the frequency of that event. For example, the twenty-five-year
return period rainfall gives the probability, 1/25 or 4%, which that
size storm will occur in any given year.
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.
A drainage conduit or pipe that collects water runoff from
a roof and leads it away from the structure.
Any part of precipitation that flows over the land surface.
Subdivision and land development ordinance.[5]
Soils or other materials transported by surface water as
a product of erosion.
The process by which mineral or organic matter is accumulated
or deposited by the movement of water or air.
The placement, discharge or any other introduction of sediment
into the waters of the commonwealth.
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. More information on seepage pits may be
found in the PA BMP Manual, December 2006, Chapter 6, Section 4.
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.
Stormwater runoff flowing in shallow, defined ruts prior
to entering a defined channel or waterway.
A flow process associated with broad, shallow water movement
on sloping ground surfaces that is not channelized or concentrated.
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)."
The zone through which contaminants, if present, are likely
to migrate and reach a drinking water well or surface water intake.
Watersheds that have been designated in Pennsylvania Code
Title 25 Environmental Protection, Chapter 93, Water Quality Standards,
as exceptional value (EV) or high quality (HQ) waters.
A conveyance that is used to pass the peak discharge of the
maximum design storm that is controlled by the stormwater facility.
The regulatory requirements to protect, maintain, reclaim,
and restore water quality under Title 25 of the Pennsylvania Code
and the Clean Streams Law.
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."
A system of pipes and/or open channels that convey intercepted
runoff and stormwater from other sources, but exclude domestic sewage
and industrial wastes.
The surface runoff generated by precipitation reaching the
ground surface.
Is abbreviated as BMPs or SWM BMPs throughout this chapter.
Any structure, natural or man-made, that, due to its condition,
design, or construction, conveys, stores, or otherwise affects stormwater
runoff quality, rate or quantity. Typical stormwater management facilities
include, but are not limited to, detention and retention basins, open
channels, storm sewers, pipes, and infiltration structures.
The watershed plan, known as the "Neshaminy Creek Watershed
Act 167 Stormwater Management Plan," for managing those land use activities
that will influence stormwater runoff quality and quantity and that
would impact the Neshaminy Creek watershed adopted by Bucks and Montgomery
Counties as required by the Act of October 4, 1978, P.L. 864 (Act
167).
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. The stormwater management
site plan will be designated as "SWM site plan" throughout this chapter.
A flow of water in a natural channel or bed, as a brook,
rivulet, or a small river.
The land area adjacent to each side of a stream; this area
is essential to maintaining water quality. (See "buffer.")
A bridge, culvert, or other structure in excess of 100 feet
in length upstream to downstream which encloses a regulated water
of the commonwealth.
The smallest drainage unit of a watershed for which stormwater
management criteria have been established in the stormwater management
plan.
The division of a single lot, tract or parcel of land or any
part thereof into two or more lots, tracts or parcels of land, including
changes in street lines or lot lines for the purpose, whether immediate
or future, of partition by the court for distribution to heirs or
devisees, transfer of ownership, rent or of building development,
including commercial and industrial sites and mobile home parks; provided,
however, that divisions of land by lease for agricultural purposes
in parcels of more than 10 acres not involving any new streets or
easements or access shall be exempt from the provisions of this article.
"Subdivision" shall include land development. Any development of a
parcel of land which involves installation of streets and/or alleys,
even though the streets and alleys may not be dedicated to public
use and the parcel may not be divided immediately for purposes of
conveyance transfer, sale or rent.
The term "subdivision" includes resubdivision and, when appropriate
to the context, shall relate to the process of subdividing or to the
land subdivided, or land development. The recombination of lots previously
subdivided shall also be considered a subdivision.
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.
A low-lying stretch of land that gathers or carries surface
water runoff.
The documentation of the stormwater management system to be used for a given development site, the contents of which are established in § 242-21.
See "forest management."
The time required 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. The tc shall be representative of the developed area, i.e., a long tc shall not be used if the majority of the proposed development
is within close proximity to the detention facility, as determined
by the Township Engineer, for those sites having unique circumstances.
Highest point of elevation in a stream channel cross section
at which a rising water level just begins to flow out of the channel
and over the floodplain.
A natural or man-made waterway, usually broad and shallow,
covered with erosion-resistant grasses, used to convey surface water.
Seasonal depressional wetlands that are covered by shallow
water for variable periods from winter to spring, but may be completely
dry for most of the summer and fall.
A channel or conveyance of surface water having a defined
bed and banks, whether natural or artificial, with perennial or intermittent
flow.
Region or area drained by a river, watercourse, or other
body of water 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 the commonwealth.
The surface and subsurface area surrounding a water supply
well, well field, or spring supplying a public water system, through
which contaminants are reasonably likely to move toward and reach
the water source.
Pond for urban runoff management that is designed to detain
urban runoff and always contains water.
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, as defined
by the United States Army Corps of Engineers, and the Pennsylvania
Department of Environmental Protection. Wetlands generally include
swamps, marshes, bogs, fens, and similar areas.
