[Ord. No. 1598, 3-9-2015]
As used in this appendix, 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 ACTIVITY
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.
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 as the result of changing the land cover
including the water, vegetation and bare soil.
APPLICANT
A person who has filed an application for approval to engage
in any regulated activity defined in Section 105 of this Ordinance.
AS-BUILT DRAWINGS
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 qualified professional at the completion of the project.
BANKFULL
The channel at the top-of-bank, or point from where water
begins to overflow onto a floodplain.
BASE FLOW
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.
BEST MANAGEMENT PRACTICES (BMP)
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 Ordinance. Stormwater BMPs
are commonly grouped into one of two broad categories or measures:
"structural" or "nonstructural." In this Ordinance, 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.
BIORETENTION
A stormwater retention area that utilizes woody and herbaceous
plants and soils to remove pollutants before infiltration occurs.
BUFFER
The area of land immediately adjacent to any stream, measured
perpendicular to and horizontally from the top-of-bank on both sides
of a stream (see "top-of-bank").
CARBONATE ROCK
Carbonate rocks are a class of sedimentary rocks composed
primarily of carbonate minerals. Carbonate sedimentary rocks include
limestone, dolostone, and dolomite. These rock types are affected
by dissolution weathering processes caused by slightly acidic groundwater.
These types of rock are susceptible to karst formation.
[Added by Ord. No. 1623, § 3, 8-8-2016]
CAVERN
A solution cavity, cave, or series of underground chambers.
[Added by Ord. No. 1623, § 3, 8-8-2016]
CHANNEL
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.
CISTERN
An underground reservoir or tank for storing rainwater.
CLAY LINER
Fine grained compacted soil that is used in the construction
of a liner that limits the rate of surface water intrusion into the
subsurface. The permeability of the clay liner shall be less than
or equal to 10
-6 centimeters per second.
This is one of many acceptable lining methods.
[Added by Ord. No. 1623, § 3, 8-8-2016]
CLOSED DEPRESSION
An area of topographic depression or ground surface elevation
lower than the surrounding land surface with no surface drainage outlet.
[Added by Ord. No. 1623, § 3, 8-8-2016]
CULVERT
A structure with its appurtenant works, which carries water
under or through an embankment or fill.
CURVE NUMBER
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.
DAM
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 any other purposes which impounds or may
impound water, or another fluid or semifluid.
DEPARTMENT
The Pennsylvania Department of Environmental Protection (PADEP).
DESIGNEE
The agent of the Montgomery County, Montgomery County Conservation
District, and/or agent of the governing body involved with the administration,
review, or enforcement of any provisions of this Ordinance by contract
or memorandum of understanding.
DESIGN PROFESSIONAL (QUALIFIED)
A Pennsylvania registered professional engineer or 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., 50-year
storm) and duration (e.g., 24-hour), used in the design and evaluation
of stormwater management systems.
DETENTION BASIN
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.
DETENTION VOLUME
The volume of runoff that is captured and released into the
waters of the commonwealth at a controlled rate.
DEVELOPER
A person, that seeks to undertake a land development or subdivision.
DEVELOPMENT
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 ordinance, development encompasses both new development
and redevelopment.
DEVELOPMENT SITE
The specific tract or parcel of land where any regulated
activity set forth in Section 105 is planned, conducted or maintained.
DIFFUSED DRAINAGE DISCHARGE
Drainage discharge that is not confined to a single point
location or channel, including sheet flow or shallow concentrated
flow.
DISAPPEARING STREAMS
A surface stream whose water rapidly infiltrates, sinks into
the ground, or enters the ground through an outcrop or sinkhole.
[Added by Ord. No. 1623, § 3, 8-8-2016]
DISCHARGE
1. (verb) To release water from a project, site, aquifer,
drainage basin or other point of interest; 2. (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."
DISCONNECTED IMPERVIOUS AREA (DIA)
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.
DISSOLUTION
The removal of soluble materials from carbonate rock by groundwater.
[Added by Ord. No. 1623, § 3, 8-8-2016]
DISTURBED AREAS
Unstabilized land area where an earth disturbance activity
is occurring or has occurred.
DITCH
A man-made waterway constructed for irrigation or stormwater
conveyance purposes.
DRAINAGE CONVEYANCE FACILITY
A stormwater management facility designed to transport stormwater
runoff that includes channels, swales, pipes, conduits, culverts,
and storm sewers.
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 municipality after the SWM site plan
has been approved.
EARTH DISTURBANCE ACTIVITY
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, 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.
EPIKARST BEDROCK
A highly-permeable top-layer of bedrock beneath the soil
layer that has been heavily solutioned and made very permeable by
groundwater.
[Added by Ord. No. 1623, § 3, 8-8-2016]
EROSION
The process by which the surface of the land, including water/stream
channels, is worn away by water, wind, or chemical action.
EROSION AND SEDIMENT CONTROL PLAN
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.
EXISTING RECHARGE AREA
Undisturbed surface area or depression where stormwater collects
and a portion of which infiltrates and replenishes the groundwater.
EXISTING RESOURCES AND SITE ANALYSIS MAP
A base map which identifies fundamental environmental site
information including floodplains, wetlands, topography, vegetative
site features, natural areas, prime agricultural land and areas supportive
of endangered species.
FAULT
A fracture of large scale in bedrock along which movement
has taken place.
[Added by Ord. No. 1623, § 3, 8-8-2016]
FINE GRAINED SOIL
Material that predominantly consists of silt and clay size
particles.
[Added by Ord. No. 1623, § 3, 8-8-2016]
FISSURE
A long, narrow opening or line of breakage made by cracking
or splitting in rock or earth.
[Added by Ord. No. 1623, § 3, 8-8-2016]
FLOOD
A temporary condition of partial or complete inundation of
land areas from the overflow of streams, rivers, and other waters
of the commonwealth.
FLOODPLAIN
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.
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
a designated height.
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.
GHOST LAKE
A surface water body that occurs intermittently and subsequently
infiltrates or evaporates.
[Added by Ord. No. 1623, § 3, 8-8-2016]
GRADE
1. (noun) A slope, usually of a road, channel or natural
ground specified in percent and shown on plans as specified herein.
2. (verb) to finish the surface of a roadbed, the top of an embankment,
or the bottom of excavation.
GROUNDWATER
Water beneath the earth's surface that supplies wells
and springs, and is often between saturated soil and rock.
GROUNDWATER RECHARGE
Replenishment of existing natural underground water supplies
from rain or overland flow.
GROUTING
Pressurized placement of cement-based or other grouts into
the overburden and/or shallow bedrock to densify soils, fill voids
and provide stabilization.
[Added by Ord. No. 1623, § 3, 8-8-2016]
HEC-HMS
The U.S. Army Corps of Engineers, Hydrologic Engineering
Center (HEC) — Hydrologic Modeling System (HMS).
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).
HISTORICAL SURFACE MINE
A disturbed area of ground, often in the form of a pit or
quarry, that is no longer used for minerals extraction.
[Added by Ord. No. 1623, § 3, 8-8-2016]
HOT SPOT
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). More information concerning hot spots may be found in Section 306A of this Ordinance.
HYDROGEOLOGY
The branch of geology concerned with water occurring underground.
[Added by Ord. No. 1623, § 3, 8-8-2016]
HYDROGRAPH
A graph representing the discharge of water versus time for
a selected point in the drainage system.
HYDROLOGIC REGIME
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.
IMPERMEABLE LINERS
A liner system that prohibits the infiltration of surface
water into the subsurface.
[Added by Ord. No. 1623, § 3, 8-8-2016]
IMPERVIOUS COVER
Any surface other than soil or mulch. For the purpose of
this code, decks, patio pavers, stone, and pervious asphalt and concrete
shall be considered impervious. The runoff curve numbers, however,
will be based upon actual surfaces.
IMPERVIOUS SURFACE
A surface that prevents the infiltration of water into the
ground. Impervious surfaces include, but are not limited to, streets,
sidewalks, pavement roofs, or driveway areas. Any surface areas designed
to be gravel or crushed stone shall be regarded as impervious surfaces.
IMPOUNDMENT
A retention or detention basin designed to retain stormwater
runoff and release it at a controlled rate.
INFILL DEVELOPMENT
Development that occurs on smaller parcels that remain undeveloped
but are within or very close proximity to urban or densely developed
areas. Infill development usually relies on existing infrastructure
and does not require an extension of water, sewer or other public
utilities.
INFILTRATION
Movement of surface water into the soil, where it is absorbed
by plant roots, evaporated into the atmosphere, or percolated downward
to recharge groundwater.
INFILTRATION STRUCTURES
A structure designed to direct runoff into the underground
water (e.g., french drains, seepage pits, or seepage trenches).
INITIAL ABSTRACTION (Ia)
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.
INLET
The upstream end of any structure through which water may
flow.
INTERMITTENT STREAM
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.
JOINTS
Deep penetrating fractures dividing rock into two sections.
[Added by Ord. No. 1623, § 3, 8-8-2016]
KARST
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.
KARST FEATURES
Evidence of karst terrain such as sinkholes, closed depressions,
ghost lakes, caverns and disappearing streams.
[Added by Ord. No. 1623, § 3, 8-8-2016]
KARST TERRAIN
The hummocky or rolling ground terrain that results from
the dissolution of soluble carbonate bedrock, such as limestone and
dolomite.
[Added by Ord. No. 1623, § 3, 8-8-2016]
LAND DEVELOPMENT
(1)
The improvement of one lot or two or more contiguous lots, tracts
or parcels of land for any purpose involving:
(a)
A group of two (2) 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
(b)
The division or allocation of land or space, whether initially
or cumulatively, between or among two (2) or more existing or prospective
occupants by means of, or for the purpose of, streets, common areas,
leaseholds, condominiums or building groups of other features.
(3)
Development in accordance with Section 503(1.1) of the PA Municipalities
Planning Code.
LINEAMENTS
A linear topographic feature of regional extent which is
an expression of an underlying geological structure such as a fault.
[Added by Ord. No. 1623, § 3, 8-8-2016]
LOT
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.
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.
MUNICIPAL ENGINEER
A professional engineer licensed as such in the Commonwealth
of Pennsylvania, duly appointed as the engineer for a municipality,
planning agency or joint planning commission.
MUNICIPALITY
Plymouth Township, Montgomery County, Pennsylvania.
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.
NONSTORMWATER DISCHARGES
Water flowing in stormwater collection facilities, such as
pipes or swales, which is not the result of a rainfall event or snowmelt.
NPDES
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.
NRCS
Natural Resource Conservation Service (previously Soil Conservation
Service).
OUTCROPS OF BEDROCK
The exposure of the rock that underlies soil or other unconsolidated
material that appears at the surface of the earth.
[Added by Ord. No. 1623, § 3, 8-8-2016]
OUTFALL
"Point source" as described in 40 CFR 122.2 at the point
where the municipality's storm sewer system discharges to surface
waters of the commonwealth.
OUTLET
Points of water disposal to a stream, river, lake, tidewater
or artificial drain.
PARENT TRACT
The parcel of land from which a land development or subdivision
originates, determined from the date of municipal adoption of this
ordinance.
PEAK DISCHARGE
The maximum rate of flow of storm runoff from a specific
storm event.
PERENNIAL STREAM
A stream which contains water at all times except during
extreme drought.
PERVIOUS SURFACE
A surface that allows the infiltration of water into the
ground, (e.g., soil or mulch).
PIPE
A culvert, closed conduit, 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 Pa. Code § 92.1.
POSTCONSTRUCTION
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.
PRETREATMENT
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 Section 304.
PROJECT SITE
The specific area of land where any regulated activities
in the municipality are planned, conducted or maintained.
QUALIFIED PROFESSIONAL
Any person licensed by the Pennsylvania Department of State
or otherwise qualified by law to perform the work required by the
Ordinance.
RECHARGE
The replenishment of groundwater through the infiltration
of rainfall, other surface waters, or land application of water or
treated wastewater.
RECORD DRAWINGS
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 PA Municipalities Planning Code (Act 247).
REDEVELOPMENT
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 percent of the street width including shoulders is removed
and repaved.
REGULATED ACTIVITIES
Any earth disturbance activities or any activities that involve
the alteration or development of land in a manner that may affect
stormwater runoff.
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.
REPAVING
Replacement of the impervious surface that does not involve
reconstruction of an existing paved (impervious) surface.
REPLACEMENT PAVING
Reconstruction of and full replacement of an existing paved
(impervious) surface.
RESIDUAL SOIL
Soils derived from the in-place weathering of the underlying
bedrock.
[Added by Ord. No. 1623, § 3, 8-8-2016]
RETENTION BASIN
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 4 days or less.
RETENTION VOLUME/REMOVED RUNOFF
The volume of runoff that is captured and not released directly
into the surface waters of the commonwealth during or after a storm
event.
RETURN PERIOD
The probability an event will occur in any given year. Typically
displayed as a whole number, e.g. 25-year event, and represents the
inverse of the frequency of that event. For example, the 25-year return
period rainfall gives the probability, 1/25 or 4%, which that size
storm will occur in any given year.
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.
ROOF DRAINS
A drainage conduit or pipe that collects water runoff from
a roof and leads it away from the structure.
RUNOFF
Any part of precipitation that flows over the land surface.
SALDO
Subdivision and Land Development Ordinance.
SCS
Soil Conservation Service, U.S. Department of Agriculture.
See "NRCS."
SEASONAL HIGH WATER TABLE
The uppermost level of the ambient water table within an
aquifer during seasons of heavy rainfall.
[Added by Ord. No. 1623, § 3, 8-8-2016]
SEDIMENT
Soils or other materials transported by surface water as
a product of erosion.
SEDIMENTATION
The process by which mineral or organic matter is accumulated
or deposited by the movement of water or air.
SEDIMENT POLLUTION
The placement, discharge or any other introduction of sediment
into the waters of the commonwealth.
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. More information on seepage pits may be found in the PA BMP Manual, December 2006, Chapter
6, Section 4.
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.
SHALLOW CONCENTRATED FLOW
Stormwater runoff flowing in shallow, defined ruts prior
to entering a defined channel or waterway.
SHEET FLOW
A flow process associated with broad, shallow water movement
on sloping ground surfaces that is not channelized or concentrated.
SINKHOLE
A localized land surface subsidence or collapse of soil where
the soil has collapsed into a soil-void or soil-cavity which directly
overlies the epikarst layer.
[Added by Ord. No. 1623, § 3, 8-8-2016]
SOIL COVER COMPLEX METHOD
A method of runoff computation developed by NRCS that is
based on relating soil type and land use/cover to a runoff parameter
called a curve number (CN).
SOIL MOTTLING
Soil mottling occurs when soils are frequently wet for long
periods of time. In water-logged soils, oxygen moves through too slowly
to aerate the soil. This causes the natural red colors in soil to
become gray spots (mottles).
[Added by Ord. No. 1623, § 3, 8-8-2016]
SOIL SCOURING
The removal of soil materials by fast flowing water.
[Added by Ord. No. 1623, § 3, 8-8-2016]
SPILLWAY
A conveyance that is used to pass the peak discharge of the
maximum design storm that is controlled by the stormwater facility.
SPRING
Where groundwater flows naturally out of the bedrock or from
the overlying soil mantle onto the land surface or into a surface
water body.
[Added by Ord. No. 1623, § 3, 8-8-2016]
STATE WATER QUALITY REQUIREMENTS
The regulatory requirements to protect, maintain, reclaim,
and restore water quality under Title 25 of the Pennsylvania Code
and the Clean Streams Law.
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, 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.
STORMWATER SWM 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 ordinance.
STREAM
A flow of water in a natural channel or bed, as a brook,
rivulet, or a small river.
STREAM BANK EROSION
The widening, deepening, or headward cutting of channels
and waterways, caused by stormwater runoff or bankfull flows.
STREAM BUFFER
The land area adjacent to each side of a stream, essential
to maintaining water quality. See "buffer."
STREAM ENCLOSURE
A bridge, culvert, or other structure in excess of 100 feet
in length upstream to downstream which encloses a regulated water
of the commonwealth.
SUBAREA (SUBWATERSHED)
The smallest unit of 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 to 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 ten acres,
not involving any new street or easement of access or any residential
dwelling, shall be exempted.
SURFACE WATER HYDROLOGY
In-depth analysis of the surface-water components of the
hydrologic cycle.
[Added by Ord. No. 1623, § 3, 8-8-2016]
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.
SWALLET
A naturally-occurring opening in the soil layer into which
stormwater drainage occurs into the underlying epikarst bedrock.
[Added by Ord. No. 1623, § 3, 8-8-2016]
SWM SITE PLAN
The documentation of the stormwater management system to
be used for a given development site, the contents of which are established
in Section 402.
TIME-OF-CONCENTRATION (Tc)
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.
TOP-OF-BANK
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.
VEGETATED SWALE
A natural or man-made waterway, usually broad and shallow,
covered with erosion-resistant grasses, used to convey surface water.
WATERCOURSE
Any channel or conveyance of surface water having defined
bed or banks, whether natural or artificial, 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 the commonwealth.
WET BASIN
Pond for urban runoff management that is designed to detain
urban runoff and always contains water.
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. Wetlands
generally include swamps, marshes, bogs, fens, and similar areas.