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 human activities and natural processes, at 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.
AGRICULTURAL PLOWING OR TILLING ACTIVITY
(1)
Earth disturbance activity involving the preparation and maintenance
of soil for the production of agricultural crops.
(2)
The term includes no-till cropping methods, which is the practice
of planting crops with minimal mechanical tillage.
APPLICANT
A landowner, developer, person, partnership, association,
corporation or other entity, or other responsible person therein or
agent thereof, who has filed an application to the Township for approval
to engage in any regulated activity at a project site in the Township.
BEST MANAGEMENT PRACTICE (BMP)
Activities, facilities, designs, measures, or procedures used to manage stormwater quantity and quality impacts from regulated activities listed in §
220-5 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.
BIORETENTION
Densely vegetated, depressed features that store stormwater
and filter it through vegetation, mulch, planting soil, etc. Ultimately,
stormwater is evapotranspirated, infiltrated or discharged. Optimal
bioretention areas mimic natural forest ecosystems in terms of species
diversity, density, distribution, use of native plants, etc.
BUFFER
(1)
STREAMSIDE BUFFERA zone of variable width located along a stream that is vegetated and is designed to filter pollutants from runoff; and
(2)
SPECIAL GEOLOGIC FEATURE BUFFERA required isolation distance from a special geologic feature to a proposed BMP needed to reduce the risk of sinkhole formation due to stormwater management activities.
CAPTURE/REUSE
Stormwater management techniques, such as cisterns and rain
barrels which direct runoff into storage devices, surface or subsurface
for later reuse, such as irrigation of gardens and other planted areas.
CARBONATE BEDROCK
Rock consisting chiefly of carbonate minerals, such as limestone
and dolomite; specifically, a sedimentary rock composed of more than
50% by weight of carbonate minerals that underlies soil or other unconsolidated
superficial material.
CHANNEL
The bed and banks of watercourses, which confine and convey
the normal flow of the water, either continuously or intermittently.
CISTERN
An underground reservoir or tank for storing rainwater.
CLOSED DEPRESSION
In a karst area, a distinctive bowl-shaped depression in
the land surface. It is characterized by internal drainage, varying
magnitude, and an unbroken ground surface.
CONSTRUCTED WETLANDS
Constructed wetlands are similar to wet ponds (see below)
and consist of a basin which provides for necessary stormwater storage
as well as a permanent pool or water level, planted with wetland vegetation.
To be successful, constructed wetlands must have adequate natural
hydrology (both runoff inputs as well as soils and water table which
allow for maintenance of a permanent pool of water). In these cases,
the permanent pool must be designed carefully, usually with shallow
edge benches, so that water levels are appropriate to support carefully
selected wetland vegetation.
CULVERT
A pipe, conduit or similar structure including appurtenant
works which carries surface water.
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.
DEP
The Pennsylvania Department of Environmental Protection.
DESIGN STORM
The depth and time distribution of precipitation from a storm
event measured in probability of occurrence (e.g., 100-year storm)
and duration (e.g., 24 hours), used in the design and evaluation of
stormwater management control systems.
DETENTION BASIN
A basin designed to retard stormwater runoff by temporarily
storing the runoff and releasing it at a predetermined rate.
DETENTION VOLUME
The volume of runoff that is captured and released into the
waters of the commonwealth at a controlled rate.
DIRECT RECHARGE/SUBSURFACE BMP
A BMP designed to direct runoff to groundwater recharge without
providing for vegetative uptake. Examples include infiltration trenches,
seepage beds, drywells, and stormwater drainage wells such that nearly
all runoff becomes recharge to groundwater.
DISTURBANCE
Any activity involving the clearing, excavating, storing,
grading, filling, or transporting of soil or any other activity which
causes soil to be exposed to the danger of erosion.
DISTURBED AREA
An unstabilized land area where an earth disturbance activity
is occurring or has occurred.
DIVERSION
A channel with or without a supporting ridge on the lower
side constructed to intercept and divert surface runoff.
DRAINAGE
The removal of surface water or groundwater from land by
drains, grading, or other means and includes control of runoff to
minimize erosion and sedimentation during and after construction or
development and means necessary for water supply preservation or prevention
or alleviation of flooding.
DRAINAGE EASEMENT
A right granted by a landowner to a grantee, allowing the
use of private land for stormwater management purposes.
DRAINAGE PLAN
The documentation of the proposed stormwater quantity and quality management controls, if any, to be used for a given development site, including a BMP operations and maintenance plan, the contents of which are established in §
220-36.
EARTH DISTURBANCE ACTIVITY
A construction or other human activity which disturbs the
surface of the land including, but not limited to, clearing and grubbing,
grading, excavations, embankments, road maintenance, building construction
and the moving, depositing, stockpiling or storing of soil, rock,
or earth materials.
EMBANKMENT
A man-made deposit of soil, rock, or other material.
EROSION
The natural process by which the surface of the land is worn
away by water, wind, ice, chemical action or other geological agents.
EXCAVATION or CUT
An act by which soil or soils are cut into, dug, quarried,
uncovered, removed, displaced, or relocated.
EXISTING CONDITION
The dominant land cover during the five-year period immediately
preceding a proposed regulated activity.
EXISTING GRADE
The vertical location of the existing ground surface prior
to cutting or filling.
EXISTING USES
Those uses actually attained in the water body on or after
November 28, 1975, whether or not they are included in the water quality
standards. (25 Pa. Code Chapter 93.1)
FEMA
Federal Emergency Management Agency.
FILL
Man-made deposits of natural soils or rock products and waste
materials.
FLOODPLAIN
Any land area susceptible to inundation by water from any
natural source or delineated by applicable FEMA maps and studies as
being a special flood hazard area. Also includes areas that comprise
Group 13 Soils, as listed in Appendix A of the Pennsylvania 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 flood. Unless otherwise specified, the boundary of the
floodway is as indicated on maps and flood insurance studies provided
by FEMA. In an area where no FEMA maps or studies have defined the
boundary of the 100-year floodway, it is assumed, absent evidence
to the contrary, that the floodway extends 50 feet from the top of
the bank of the stream.
FOREST MANAGEMENT/TIMBER OPERATIONS
Planning and activities necessary for the management of forestland.
These include conducting a timber inventory, preparation of forest
management plans, silvicultural treatment, cutting budgets, logging
road design and construction, timber harvesting, site preparation,
and reforestation.
FREEBOARD
The incremental depth in a stormwater management structure,
provided as a safety factor of design, above that required to convey
the design runoff event.
GRADING
Any stripping, cutting, filling, stockpiling or any combination
thereof and shall include the land in its cut or filled condition.
GREEN INFRASTRUCTURE
Systems and practices that use or mimic natural processes
to infiltrate, evapotranspire, or reuse stormwater on the site where
it is generated.
GROUND FLOOR
The first floor of a building other than a cellar or basement,
as those areas are defined in the Township-adopted Building Code.
HARDSHIP WAIVER REQUEST
A written request for a waiver alleging that the provisions
of this chapter inflict unnecessary hardship upon the applicant. Hardship
waiver does not apply to and is not available from the water quality
provisions of this chapter, and shall not be granted.
HOT SPOT LAND USES
A land use or activity that generates higher concentrations of hydrocarbons, trace metals or other toxic substances than typically found in stormwater runoff. These land uses are listed in §
220-18P.
HYDROLOGIC SOIL GROUP (HSG)
Infiltration rates of soils vary widely and are affected
by subsurface permeability as well as surface intake rates. Soils
are classified into four HSGs (A, B, C, and D) to indicate the minimum
infiltration rates, which are obtained for bare soil after prolonged
wetting. The Natural Resources Conservation Service (NRCS) defines
the four groups and provides a list of most of the soils in the United
States and their group classification. The soils in the area of the
development site may be identified from a soil survey report that
can be obtained from local NRCS offices or conservation district offices.
Soils become less pervious as the HSG varies from A to D (NRCS 1,2).
IMPERVIOUS SURFACE (IMPERVIOUS COVER)
A surface which prevents the percolation of water into the
ground. Impervious surfaces (or areas) shall include, but not be limited
to: roofs; additional indoor living spaces, swimming pools, patios,
garages, storage sheds and similar structures; and any paved streets,
sidewalks, driveways, and parking areas. Decks, parking areas, and
driveway areas are not counted as impervious areas if they do not
prevent infiltration.
INFILTRATION PRACTICE
A practice designed to allow direct runoff an opportunity
to infiltrate into the ground (e.g., french drain, seepage pit, seepage
trench or bioretention area).
INFILTRATION STRUCTURE
A structure designed to direct runoff into the ground (e.g.,
french drain, seepage pit, or seepage trench).
KARST
A type of topography or landscape characterized by surface
depressions, sinkholes, rock pinnacles/uneven bedrock surface, underground
drainage, and/or caves. Karst is usually formed on carbonate rocks,
such as limestones or dolomites.
LAND DEVELOPMENT
See definition in the Township Subdivision and Land Development
Ordinance ("SALDO") and the MPC.
LOADING RATE
The ratio of the land area draining to the system, as modified by the weighting factors in §
220-18B compared to the base area of the infiltration system.
LOW-IMPACT DEVELOPMENT
Site design approaches and small-scale stormwater management
practices that promote the use of natural systems for infiltration,
evapotranspiration, and reuse of rainwater. Low-impact development
can be applied to new development, urban retrofits, and revitalization
projects. Low-impact development utilizes design techniques that infiltrate,
filter, evaporate, and store runoff close to its source. Rather than
rely on costly large-scale conveyance and treatment systems, low-impact
development addresses stormwater through a variety of small, cost-effective
landscape features located on-site.
LOWEST FLOOR
Lowest floor of the enclosed area, including basements and
cellars, as those areas are defined in the Township-adopted Building
Code.
LVPC
Lehigh Valley Planning Commission.
MAINSTEM (MAIN CHANNEL)
Any stream segment or other conveyance used as a reach in
the Bushkill Creek, Fry's Run, Monocacy Creek, or Nancy Run hydrologic
models.
MANNING'S EQUATION (MANNING'S 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.
MARYLAND STORMWATER DESIGN MANUAL
A stormwater design manual written by the Maryland Department
of the Environment and the Center for Watershed Protection. The manual
can be obtained through the following website: www.mde.state.md.us.
MINIMUM DISTURBANCE/MINIMUM MAINTENANCE PRACTICES (MD/MM)
A site design practice in which careful limits are placed
on site clearance prior to development allowing for maximum retention
of existing vegetation (woodlands and other), minimum disturbance
and compaction of existing soil mantle and minimum site application
of chemicals post-development. Typically, MD/MM includes disturbance
setback criteria from buildings as well as related site improvements
such as walkways, driveways, roadways, and any other improvements.
This criteria may vary by community context as well as by type of
development being proposed. Additionally, MD/MM also shall include
provisions (e.g., deed restrictions, conservation easements) to protect
these areas from future disturbance and from application of fertilizers,
pesticides and herbicides.
NO HARM RUNOFF QUANTITY OPTION
The option of using a less restrictive runoff quantity control
if it can be shown that adequate and safe runoff conveyance exists
and that the less restrictive control would not adversely affect health,
safety, and property.
NRCS
USDA Natural Resource Conservation Service (formerly the
Soil Conservation Service).
OBSTRUCTION
Any structure, materials, fill or activity that would impede,
retard, or change natural or approved stormwater flows.
OIL/WATER SEPARATOR
A structural mechanism designed to remove free oil and grease
(and possibly solids) from stormwater runoff.
OUTFALL
"Point source" as described in 40 CFR 122.2 at the point
where the Township's storm sewerage system discharges to waters
of the commonwealth.
OWNER
One with an interest in and often dominion over a property.
PARENT TRACT
A lot or tract of land with its condition considered at the
time of the Township adoption of the original Bushkill Creek, Fry's
Run, Monocacy Creek, and Nancy Run Act 167 Stormwater Management Ordinances
(May 1992, February 1999, March 1989, and March 1989, respectively).
A parent tract is all contiguous land held in single and separate
ownership, regardless of whether such land is divided into one or
more lots, parcels, purparts, or tracts; such land was acquired by
the landowner at different times or by different deeds, devise, partition
or otherwise; or such land is bisected by public or private streets
or rights-of-way. Single and separate ownership is the ownership of
property by any person, partnership, or corporation.
PEAK DISCHARGE
The maximum rate of flow of stormwater runoff at a given
location and time resulting from a specific storm event.
PENN STATE RUNOFF MODEL (PSRM)
The computer-based hydrologic modeling technique adapted
to each watershed for the Act 167 plans. The model was calibrated
to reflect actual flow values by adjusting key model input parameters.
PERSON
An individual, partnership, public or private association
or corporation, or a governmental unit, public utility or other for-
or not-for-profit statutory entity or other legal entity whatsoever
which is recognized by law as the subject of rights and duties.
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.
POROUS PAVEMENT
A specific type of pavement with a high porosity that allows
rainwater to pass through it into the ground below.
PRELIMINARY SITE INVESTIGATION
The determination of the depth to bedrock, the depth to the
seasonal high-water table and the soil permeability for a possible
infiltration location on a site through the use of published data
and on-site surveys. In carbonate bedrock areas, the location of special
geologic features must also be determined along with the associated
buffer distance to the possible infiltration area.
PRETREATMENT
Measures implemented for hot spot land uses designed to reduce
concentration of hydrocarbons, trace metals, and other toxic substances
to levels typically found in stormwater runoff.
PROJECT SITE
The specific area of land where any regulated activities
in the Township are planned, conducted, or maintained.
PUBLIC WATER SYSTEM
A system which provides water to the public for human consumption
which has at least 15 service connections or regularly serves an average
of at least 25 individuals daily at least 60 days out of the year.
(See 25 Pa. Code Chapter 109.)
QUALIFIED PROFESSIONAL
Any person licensed by the Pennsylvania Department of State
or otherwise qualified by law to perform work required by this chapter.
RATIONAL METHOD
A method of peak runoff calculation using a standardized
runoff coefficient (rational "c"), acreage of tract and rainfall intensity
determined by return period and by the time necessary for the entire
tract to contribute runoff. The Rational Formula is stated as follows:
Q = ciA, where "Q" is the calculated peak flow rate in cubic feet
per second, "c" is the dimensionless runoff coefficient (see Appendix
C "I" is the rainfall intensity in inches per hour, and
"A" is the area of the tract in acres. (The Rational Method formula
for runoff volume calculation is as follows: V = cPA/12, where "c"
and "A" are as noted above, "P" is the total depth of precipitation
for the design event in inches, and "V" is the total runoff volume
in acre-feet.)
REACH
Any of the natural or man-made runoff conveyance channels
used for watershed modeling purposes to connect the subareas and transport
flows downstream.
RECHARGE VOLUME (REv)
The portion of the water quality volume (WQv) used to maintain groundwater recharge rates at development sites. (See §
220-18J.)
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 and which are governed by this chapter as specified in §
220-5D.
REGULATED EARTH DISTURBANCE ACTIVITY
Activity involving earth disturbance, other than agricultural
plowing or tilling, subject to regulation under 25 Pa. Code Chapter
92, 25 Pa. Code Chapter 102, or the Clean Streams Law. Earth disturbance activity other than agricultural plowing
or tilling of one acre or more with a point source discharge to surface
waters or to the Township's storm sewer system or earth disturbance
activity of 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 the predevelopment peak rate of runoff
for a development site to which the post-development peak rate of
runoff must be controlled to avoid peak flow increases throughout
the watershed.
RETURN PERIOD
The average interval, in years, within which a storm event
of a given magnitude can be expected to occur one time. For example,
the twenty-five-year return period rainfall would be expected to occur
on average once every 25 years; or, stated in another way, the probability
of a twenty-five-year storm occurring in any one year is 0.04 (i.e.,
a 4% chance).
RIPARIAN BUFFER
A permanent area of trees and shrubs located adjacent to
streams, lakes, ponds, and wetlands.
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.
RUNOFF
That part of precipitation which flows over the land.
RUNOFF BMP
A BMP designed for essentially the full volume of runoff
entering the BMP to be discharged off-site.
SEDIMENT
Soils or other materials transported by surface water as
a product of erosion.
SEDIMENT TRAPS/CATCH BASIN SUMPS
A chamber which provides storage below the outlet in a storm
inlet to collect sediment, debris, and associated pollutants, typically
requiring periodic cleanout.
SEEPAGE PIT/SEEPAGE TRENCH
An area of excavated earth filled with loose stone or similar
material and 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
Stormwater runoff flowing in a thin layer over the ground
surface.
SOIL-COVER-COMPLEX METHOD
A method of runoff computation developed by NRCS which is
based upon relating soil type and land use/cover to a runoff parameter
called a "curve number."
SPECIAL GEOLOGIC FEATURES
Carbonate bedrock features including, but not limited to,
closed depressions, existing sinkholes, fracture traces, lineaments,
joints, faults, caves, and pinnacles, which may exist and must be
identified on a site when stormwater management BMPs are being considered.
SPILL PREVENTION AND RESPONSE PROGRAM
A program that identifies procedures for preventing and,
as needed, cleaning up potential spills and makes such procedures
known and the necessary equipment available to appropriate personnel.
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, including:
(1)
Each stream segment in Pennsylvania has a "designated use,"
such as "cold water fishes" 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; and
(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 method of routing or moving an inflow hydrograph through
a reservoir or detention structure. The method solves the mass conservation
equation to determine an outflow hydrograph as it leaves the storage
facility.
STORM DRAINAGE PROBLEM AREAS
Areas which lack adequate stormwater collection and/or conveyance
facilities and which present a hazard to persons or property. These
areas are either documented in Appendix B of this chapter or identified by the Township or Township Engineer.
STORM SEWER
A system of pipes 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 DETENTION
The holding or slowing down of stormwater runoff to limit
the amounts of post-development runoff (release rate) to a required
percentage of the predevelopment amounts of runoff during peak periods.
STORMWATER DRAINAGE WELLS
Wells for injection of stormwater to the surface that are
regulated by the U.S. Environmental Protection Agency to protect underground
sources of drinking water.
STORMWATER FILTERS
Any number of structural mechanisms such as multichamber
catch basins, sand/peat filters, sand filters and so forth, which
are installed to intercept stormwater flow and remove pollutants prior
to discharge. Typically, these systems require periodic maintenance
and cleanout.
STORMWATER MANAGEMENT DISTRICT
Individual areas as they appear on the Bushkill Creek, Fry's
Run, Monocacy Creek and Nancy Run release rate maps. Each district
is assigned an allowable release rate.
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 limited
to: detention and retention basins; open channels; storm sewers; pipes;
and infiltration facilities.
STORMWATER MANAGEMENT PLAN
The plan for managing stormwater runoff adopted by Northampton
County for the Bushkill Creek, Fry's Run, Monocacy Creek, and
Nancy Run watersheds as required by the Act of October 4, 1978, P.L.
864 (Act 167), as amended, and known as the "Storm Water Management
Act."
STORMWATER MANAGEMENT SITE PLAN
The plan prepared by the developer or its representative indicating how stormwater runoff will be managed at a development site in accordance with this chapter, in cases as outlined in §
220-47.
SUBAREA
The smallest unit of watershed breakdown for hydrologic modeling
purposes for which the runoff control criteria have been established
in the stormwater management plan.
SUBDIVISION
As defined in the Pennsylvania Municipalities Planning Code,
Act of July 31, 1968, P.L. 805, No. 247, and the Township Subdivision
and Land Development Ordinance.
SURFACE WATERS
Perennial and intermittent streams, rivers, lakes, reservoirs,
ponds, wetlands, springs, natural seeps, and estuaries, excluding
water at facilities approved for wastewater treatment such as wastewater
treatment impoundments, cooling water ponds and constructed wetlands
used as part of a wastewater process.
SWALE
A low-lying stretch of land which gathers or carries surface
water runoff. See also "vegetated swale."
TIMBER HARVESTING ACTIVITIES
Earth disturbance activities, including the construction
of skid trails, logging roads, landing areas and other similar logging
or silvicultural practices.
TOWNSHIP
Bethlehem Township, Northampton County, Pennsylvania.
TRASH/DEBRIS COLLECTORS
Racks, screens or other similar devices installed in a storm
drainage system to capture coarse pollutants (trash, leaves, etc.).
USDA
United States Department of Agriculture.
VEGETATED BUFFERS
Gently sloping areas that convey stormwater as sheet flow
over a broad, densely vegetated earthen area, possibly coupled with
the use of level spreading devices. As water quality BMPs, vegetated
buffers serve to filter pollutants from runoff and promote infiltration.
Vegetated buffers should be situated on minimally disturbed soils,
have low-flow velocities and extended residence times. Vegetated buffers
may be, but are not restricted to, use in riparian (streamside) conditions.
VEGETATED ROOFS
Vegetated systems installed on roofs that generally consist
of a waterproof layer, a root-barrier, drainage layer (optional),
growth media and suitable vegetation. Vegetated roofs store and eventually
evapotranspirate the collected rooftop rainfall; overflows may be
provided for larger storms.
VEGETATED SWALES
(1)
Vegetated earthen channels designed to convey and possibly treat
stormwater. These swales are not considered to be water quality BMPs;
and
(2)
Broad, shallow, densely vegetated earthen channels designed
to treat stormwater while slowly infiltrating, evapotranspirating,
and conveying it. Swales should be gently sloping with low flow velocities
to prevent erosion. Check dams may be added to enhance performance.
VEGETATED/SURFACE BMP
A BMP designed to provide vegetative uptake and soil renovation
or surface infiltration of runoff. Capture/reuse BMPs are included
if the captured runoff is applied to vegetated areas. Examples include
bioretention and surface infiltration basins.
WATER QUALITY INSERTS
Any number of commercially available devices that are inserted
into storm inlets to capture sediment, oil, grease, metals, trash,
debris, etc.
WATERCOURSE
Any channel or conveyance of surface water having defined
bed and banks, whether natural or artificial, with perennial or intermittent
flow.
WATERS OF THE COMMONWEALTH
Any and all rivers, streams, creeks, rivulets, impoundments,
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.
WATERSHED
Region or area drained by a river or other body of water
whether natural or artificial.
WET DETENTION PONDS
A basin that provides necessary stormwater storage as well
as a permanent pool of water. To be successful, wet ponds must have
adequate natural hydrology (both runoff inputs as well as soils and
water table which allow for maintenance of a permanent pool of water)
and must be able to support a healthy aquatic community so as to avoid
creation of mosquito and other health and nuisance problems.
WETLAND
Areas that are inundated or saturated by surface water or
groundwater at a frequency and duration sufficient to support, and
that under normal circumstances do support, a prevalence of vegetation
typically adapted for life in saturated soil conditions, including
swamps, marshes, bogs, and similar areas.