A.
For the purposes of this chapter, certain terms and words used herein
shall be interpreted as follows:
(1)
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.
(2)
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.
(3)
The word "person" includes an individual, firm, association, organization,
partnership, trust, company, corporation, or any other similar entity.
(4)
The words "shall" and "must" are mandatory; the words "may" and "should"
are permissive.
(5)
The words "used or occupied" include the words "intended, designed,
maintained, or arranged to be used, occupied or maintained."
B.
ACCELERATED EROSION
AGRICULTURAL ACTIVITY
ALTERATION
APPLICANT
BEST MANAGEMENT PRACTICES (BMPs)
BMP MANUAL (Pennsylvania Stormwater Best Management Practices
Manual) - December 2006 and Most Recent Revisions)
CHANNEL EROSION
CONSERVATION DISTRICT
CULVERT
DAM
DESIGNEE
DESIGN STORM
DETENTION BASIN
DETENTION VOLUME
DEVELOPER
DEVELOPMENT SITE
DISTURBED AREA
DOWN-SLOPE PROPERTY BOUNDARY
DRAINAGE CONVEYANCE FACILITY
DRAINAGE EASEMENT
DRAINAGE PERMIT
DRAINAGE PLAN
EARTH DISTURBANCE ACTIVITY
EROSION
EROSION AND SEDIMENT POLLUTION CONTROL PLAN (E&S Plan)
EXISTING CONDITIONS
FEMA
FLOOD
FLOODPLAIN
FLOODWAY
FOREST MANAGEMENT/TIMBER OPERATIONS
FREEBOARD
GRADE
GRASSED WATERWAY
GROUNDWATER RECHARGE
HYDROLOGIC SOIL GROUP (HSG)
IMPERVIOUS SURFACE (IMPERVIOUS AREA)
IMPOUNDMENT
INFILTRATION STRUCTURES
INLET
KARST
LAND DEVELOPMENT
(1)
(a)
(b)
(2)
(3)
(a)
(b)
(c)
LAND/EARTH DISTURBANCE
MANNING EQUATION (MANNING FORMULA)
MAXIMUM WATER DEPTH
MS4-MUNICIPAL SEPARATE STORM SEWER SYSTEM
NONPOINT SOURCE POLLUTION
NPDES
NRCS - USDA
OPEN CHANNEL
OUTFALL
OUTLET
PADEP
PARCEL
PEAK DISCHARGE
PERVIOUS AREA
PIPE
PLANNING COMMISSION
POINT SOURCE
PROJECT SITE
QUALIFIED DESIGN PROFESSIONAL
RATIONAL FORMULA
REDEVELOPMENT
REGULATED ACTIVITIES
REGULATED EARTH DISTURBANCE ACTIVITY
RETENTION BASIN
RETURN PERIOD
RIPARIAN CORRIDOR
RUNOFF
SEDIMENT
SEDIMENTATION
SEDIMENT BASIN
SEDIMENT POLLUTION
SEEPAGE PIT/SEEPAGE TRENCH
SHEET FLOW
SOIL-COVER COMPLEX METHOD
SOIL GROUP, HYDROLOGIC
SPILLWAY
STATE WATER QUALITY REQUIREMENTS
(1)
(2)
(3)
STORAGE INDICATION METHOD
STORM FREQUENCY
STORM SEWER
STORMWATER
STORMWATER MANAGEMENT BASIN
STORMWATER MANAGEMENT BEST MANAGEMENT PRACTICES
STORMWATER MANAGEMENT FACILITY
STORMWATER MANAGEMENT PLAN (DRAINAGE PLAN)
STREAM ENCLOSURE
SUBDIVISION
SURFACE WATERS OF THE COMMONWEALTH
SWALE
TIMBER OPERATIONS
TIME OF CONCENTRATION (Tc)
TOWNSHIP
USDA
WATERCOURSE
WATERSHED
WETLAND
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; land disturbance.
A landowner, developer, equitable owner, tenant, or contractor who, with written consent of the landowner, has filed an application for approval to engage in any regulated activities as defined in § 132-4 of this chapter, including his heirs, successors, and assigns.
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" refers 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 waterways, riparian
or forested buffers, sand filters, detention basins, and manufactured
devices. Structural stormwater BMPs are permanent appurtenances to
the project site.
Stormwater structures, facilities and techniques to ensure
effective stormwater management to minimize the adverse impacts of
stormwater on groundwater and surface water resources to support and
sustain the social, economic and environmental quality of the Commonwealth
of Pennsylvania.
The widening, deepening, and headward cutting of small channels
and waterways.
The Montgomery County Conservation District, operating pursuant
to the Conservation District Law [3 P.S. § 851(c)], and
which has the authority under a delegation agreement executed with
PADEP to administer and enforce all or a portion of the regulations
promulgated under 25 Pa. Code Chapter 102.
A structure with appurtenant works which carries a stream
under or through an embankment or fill.
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.
The agent of the Township involved with the administration,
review or enforcement of any provisions of this chapter by contract
or memorandum of understanding.
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 refer to "return
period."
A water impoundment which creates temporary water surface
during rain events, made by constructing a dam or embankment or by
excavating a pit, for the purpose of detaining runoff water for a
period of time and releasing it slowly into the ground or into its
natural watercourse until the temporary water surface is extinguished
and the area is dry.
The volume of runoff that is captured and released into the
waters of this commonwealth at a controlled rate.
A person, landowner, tenant, partnership, association, corporation,
or other entity, or any responsible person therein or agent thereof,
that undertakes any regulated activity of this chapter.
The specific tract of land for which a regulated activity
is proposed. Also refer to "project site."
An unstabilized land area where an earth disturbance activity
is occurring or has occurred.
That portion of the property line of the lot, tract, or parcels
of land being developed located such that overland, stream channel,
swale, or pipe flow from the site would be directed towards it.
A stormwater management facility designed to transmit stormwater
runoff, and shall include streams, channels, swales, pipes, conduits,
culverts, storm sewers, etc.
An area recorded, or to be recorded, in the Montgomery County
Recorder of Deeds Office, secured for the preservation of natural
drainageways, stream corridors and perennial and/or intermittent streams,
and for man-made drainage facilities related thereto.
A permit issued by the Township after the drainage plan has
been approved. Said permit is issued prior to or with the final Township
approval.
The documentation of the stormwater management system, if any, to be used for a given development site, the content requirements of which are established in § 132-18.
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. Earth disturbance activity is subject to regulation
under 25 Pa. Code Chapter 92,[1] 25 Pa. Code Chapter 102, or the Clean Streams Law.[2]
The natural process by which the surface of the land is worn
away by water, wind, ice, chemical action, or other natural forces.
A plan which is designed to minimize accelerated erosion
and sedimentation pursuant to 25 Pa. Code Chapter 102.
The dominant land cover during the five-year period immediately
preceding a proposed regulated activity. If the initial condition
of the site is crop or farmed land, the land use shall be considered
as "pasture" for the purpose of stormwater management calculations.
Federal Emergency Management Agency.
A general but temporary condition of partial or complete
inundation of normally dry land areas from the overflow of streams,
rivers, and other waters of this commonwealth.
Refer to Towamencin Township Zoning Ordinance, Chapter 153 of the Township Code.
Refer to Towamencin Township Zoning Ordinance, Chapter 153 of the Township Code.
Planning and 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, site preparation and reforestation.
A vertical distance between the elevation of the design high
water and the top of a dam, levee, tank, basin, channel, swale, or
diversion ridge. The space is required as a safety margin.
(1) A slope, usually of a road, channel or natural ground,
showing the degree of rise or descent of a sloping surface, specified
in percent and shown on plans as specified herein;
(2) The proposed finished elevation of the surface of a roadbed,
top of an embankment or bottom of an excavation.
A natural or constructed waterway, usually broad and shallow,
covered with erosion-resistant grasses, used to conduct surface water
from cropland or developed areas.
Replenishment of existing natural underground water supplies
through natural seepage or man-made seepage/infiltration structures.
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) according to their
minimum infiltration rate, which is obtained for bare soil after prolonged
wetting. The 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 the Montgomery County Conservation District. Soils become less
pervious as the HSG varies from A to D.
A surface that prevents the infiltration of water into the
ground. Impervious surface area shall include, but not be limited
to, buildings, parking areas, driveways, roads, and sidewalks. Any
areas containing concrete, asphalt, compacted stone, compacted soils,
or other equivalent surfaces shall be considered impervious surface
within this definition. In addition, other areas determined by the
Township Engineer to be impervious within the meaning of this definition
shall be classified as impervious surface. Any area initially designated
to be gravel or crushed stone shall be regarded as impervious surface.
Decks, parking areas, and driveway areas are not counted as impervious
areas if they do not prevent infiltration.
A retention or detention basin designed to retain stormwater
runoff and release it at a controlled rate.
A structure designed to collect and impound runoff so it
seeps into the ground (including but not limited to french drains,
seepage pits, seepage trenches, etc.).
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.
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.
Any subdivision of land.
The following activities are excluded from this definition:
The conversion of an existing single-family dwelling, detached
dwelling or single-family semidetached dwelling into not more than
three residential units, unless such units are intended to be a condominium;
The addition of an accessory building, including farm buildings,
on a lot or lots subordinate to an existing principal building; or
The addition or conversion of buildings or rides within the
confines of an enterprise which would be considered an amusement park.
For purposes of this subsection, an amusement park is defined as a
tract or area used principally as a location for permanent amusement
structures or rides. This exclusion shall not apply to newly acquired
acreage by an amusement park until initial plans for the expanded
area have been approved by proper authorities.
Any activity involving removing, grading, tilling, digging,
or filling of ground or stripping of vegetation or any other activity
that causes an alteration to the natural condition of the land.
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.
The depth of water in the basin measured from the lowest
finished grade elevation of the basin to the maximum water surface
elevation during the one-hundred-year storm event.
Pursuant to 40 CFR 122.26(b)(8), municipal separate storm
sewer system is a conveyance or system of conveyances (including roads
with drainage systems, municipal streets, catch basins, curbs, gutters,
ditches, man-made channels, or storm drains): i) owned or operated
by a state, city, town, borough, county, parish, district, association,
or other public body (created to or pursuant to state law), including
special districts under state law such as a sewer district, flood
control district or drainage district, or similar entity, or an Indian
tribe or an authorized Indian tribal organization, or a designated
and approved management agency under section 208 of the Clean Water
Act[3] that discharges into waters of the United States; ii)
designed or used for collecting or conveying stormwater; iii) which
is not a combined sewer; and iv) which is not part of a publicly owned
treatment works as defined at 40 CFR 122.2.
Pollution that enters a water body or watercourse from diffuse
origins in the watershed and does not result from discernible, confined,
or discrete conveyances or origin.
National Pollutant Discharge Elimination System, the federal
government's system for issuance of permits under the Clean Water
Act,[4] which is delegated to PADEP in Pennsylvania.
Natural Resource Conservation Service (previously SCS).
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).
"Point source" as described in 40 CFR 122.2 at the point
where the Township's storm sewer system (MS4) discharges to surface
waters of the commonwealth.
Points of water disposal from a stream, river, lake, tidewater
or artificial drain.
Pennsylvania Department of Environmental Protection.
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.
The maximum flow rate of stormwater runoff from a specific
storm event.
Any area not defined as impervious.
A culvert, closed conduit, or similar structure (including
appurtenances) that conveys stormwater.
The Planning Commission of Towamencin Township, Montgomery
County, Pennsylvania.
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.[5]
The specific area of land where any regulated activities
in the Township are planned, conducted, or maintained.
A professional engineer, landscape architect, professional
land surveyor, or other person licensed by the Commonwealth of Pennsylvania,
qualified by law to perform the work required by this chapter.
A rainfall-runoff relation equation used to estimate peak
stormwater flow rate.
Earth disturbance activities on land which has previously
been disturbed or developed; 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.
Actions or proposed actions that may have an impact on stormwater runoff, contribute nonstormwater discharges to a regulated small MS4 and that which are specified in § 132-4 of this chapter.
Activity involving earth disturbance subject to regulation
under 25 Pa. Code Chapter 92,[6] 25 Pa. Code Chapter 102, or the Clean Streams Law;[7] a construction or other human activity which disturbs
the surface of the land, including land clearing and grubbing, grading,
excavations, embankments, land development, agricultural plowing or
tilling, operation of animal heavy use areas, timber harvesting activities,
road maintenance activities, oil and gas activities, well drilling,
mineral extraction, and the moving, depositing, stockpiling, or storing
of soil, rock or earth materials. The implementation and maintenance
of erosion and sediment control BMPs are required to minimize the
potential for accelerated erosion and sedimentation, including for
those activities which disturb less than 5,000 square feet. A written
erosion control plan is required for activities that disturb 5,000
square feet or more of land.
An aboveground stormwater runoff storage facility with a
permanent water surface elevation.
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 four-percent-chance).
Those lands adjacent to designated streams, wetlands, pond/lake
areas, and lands adjacent to designated intermittent watercourses
within Towamencin Township. Riparian Corridor Zone 1 shall be a minimum
of 25 feet wide measured horizontally on both sides from the top of
bank of the identified waterway. Clear cutting of trees, select cutting
of trees, and clearing of other vegetation is prohibited in Zone 1
unless approved by the Township.
Any part of precipitation that flows over the land surface.
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 wind, water, or by gravity. Once this
matter is deposited (or remains suspended in water), it is usually
referred to as "sediment."
A barrier, dam, retention or detention basin designed to
retain rock, sand, gravel, silt, or other material transported by
water.
The placement, discharge or introduction of sediment into
the surface 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 ground for the purpose of groundwater recharge.
Runoff that flows over the ground surface as a thin, even
layer, not concentrated in a swale, stream channel or a pipe.
A method of stormwater flow runoff computation developed
by the NRCS that is based on relating soil type and land use/cover
to a runoff parameter called a "curve number" (CN).
A classification of soils by the Soil Conservation Service
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.
A depression in the embankment of a pond or basin, which
is used to pass peak discharge greater than the maximum design storm
controlled by the pond or basin.
As defined under the Clean Streams Law[8] and state regulations, protection of designated and existing stream uses (refer to 25 Pa. Code Chapters 93 and 96), including:
Each stream segment in Pennsylvania has a designated use, such as cold water fishery or potable water supply, which are listed in 25 Pa. Code Chapter 93. These uses must be protected and maintained, under state regulations.
"Existing uses" are those attained as of November 1975, regardless of whether they have been designated in 25 Pa. Code 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.
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 streambank, streambed
and structural integrity of the waterway to prevent these impacts.
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.
The number of times that a given storm event occurs or is
exceeded on the average in a stated period of years. Refer to "return
period."
A system of pipes and/or open channels that convey intercepted
runoff and stormwater from other sources to a downstream outlet, but
exclude domestic sewage and industrial wastes.
Drainage runoff from the surface of the land resulting from
precipitation or snow or ice melt.
A detention basin or retention basin.
Is abbreviated as "BMPs" throughout this chapter. Also refer
to "best management practices."
Any structure, natural or man-made, that, due to its condition,
design, or construction, conveys, stores, or otherwise affects stormwater
runoff. Typical stormwater management facilities include, but are
not limited to, detention and retention basins, open channels, storm
sewers, pipes, and infiltration structures.
A plan prepared by the developer or his representative indicating
how stormwater runoff will be managed at the project site of interest
in accordance with this chapter. "Stormwater management plan" shall
be considered the same as "drainage plan" where referenced throughout
this chapter.
A bridge, culvert, or other structure, as defined by 25 Pa.
Code Chapter 105, which encloses a regulated water of the Commonwealth
of Pennsylvania.
The division or redivision of a lot, tract, or parcel of
land by any means into two or more lots, tracts, parcels or other
divisions of land, including changes in existing lot lines for the
purpose, whether immediate or future, of lease, partition 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 10 acres
not involving any new street or easement of access or any residential
dwelling shall be exempted.
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 which gathers or carries surface
water runoff.
Refer to "forest management timber operations."
The time for surface runoff to travel from the hydraulically
most distant point of the watershed to a point of interest within
the watershed. This time is the combined total of overland flow time
and flow time in pipes or channels, if any.
Towamencin Township, Montgomery County, Pennsylvania.
United States Department of Agriculture.
A stream of water; river; brook; creek; or a channel or ditch
for water, whether natural or man-made.
Region or area drained by a river, watercourse or other surface
water of the commonwealth.
Those 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, fens, and similar areas, which meet the characteristics
and criteria established by the Pennsylvania Department of Environmental
Protection, the U.S. Army Corp of Engineers and/or the Pennsylvania
Fish and Wildlife Service.
[1]
Editor's Note: See now 25 Pa. Code Chapter 92a.
[2]
Editor's Note: See 35 P.S. § 691.1 et seq.
[3]
Editor's Note: See 33 U.S.C. § 1251 et seq.
[4]
Editor's Note: See 33 U.S.C. § 1251 et seq.
[5]
Editor's Note: See now 25 Pa. Code § 92a.2.
[6]
Editor's Note: See now 25 Pa. Code Chapter 92a.
[7]
Editor's Note: See 35 P.S. § 691.1 et seq.
[8]
Editor's Note: See 35 P.S. § 691.1 et seq.
