For the purposes of this chapter, the words
and terms used herein shall be interpreted as follows:
A.
Words used in the present tense include the future
tense; the singular number includes the plural; 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 words "shall" and "must" are mandatory; the words
"may" and "should" are permissive.
D.
Any word, term or phrase used in this chapter, but
not specifically defined herein, or defined in the Pennsylvania Municipalities
Planning Code, as amended, or defined in the Skippack Township Subdivision
and Land Development Ordinance,[1] as amended, shall be given its normal and customary meaning
as found in the most recent edition of Webster's New Collegiate Dictionary.
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 human activities and the natural processes, at a rate greater
than would occur because of the natural process alone.
Refers to the low area adjoining and including any water
or drainage course or body of water subject to periodic flooding or
overflow and delineated as alluvial soils or local alluvium by the
Soil Conservation Service, United States Department of Agriculture,
in the Soil Survey of Montgomery County, Pennsylvania, 1967. The boundary
for this floodplain must be verified using hydrologic and hydraulic
engineering studies.
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;
the changing of surface conditions by causing the surface to be more
or less impervious; or, earth disturbance.
A landowner, developer or other person who has filed an application
for approval to engage in any regulated earth disturbance activity
at a project site in the Township.
Activities, facilities, designs, measures or landscape/vegetative
procedures used to manage stormwater impacts from regulated earth
disturbance activities, to meet state water quality requirements,
to promote groundwater recharge and to otherwise meet the purposes
of this chapter. BMPs include, but are not limited to, infiltration,
filter strips, low-impact design, bioretention, wet ponds, permeable
paving, grassed swales, forested buffers, sand filters and detention
basins.
A plan prepared by the developer or his representative indicating
how stormwater runoff will be managed at the particular site of interest
according to this chapter.
The diameter of the main trunk of a tree. Caliper measurement
shall be taken at a point on the trunk six inches above natural ground
line for trees up to four inches in caliper and at a point 12 inches
above the natural ground line for trees over four inches in caliper.
The Montgomery County Conservation District.
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 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.
The agent of Skippack Township involved with the administration,
review or enforcement of any provisions of this chapter by contract
or memorandum of understanding.
An impoundment structure designed to manage stormwater runoff
by temporarily storing the runoff and releasing it at a predetermined
rate.
The Pennsylvania Department of Environmental Protection.
A person that seeks to undertake any regulated earth disturbance
activities at a project site in the Township.
See "earth disturbance activity." The term includes redevelopment.
The specific tract of land where any earth disturbance activities
in Skippack Township are planned, conducted or maintained.
The outflow of water, silt or other mobile substances passing
along a conduit, watercourse or channel or released from any type
of detention basin or stormwater management facility.
A right granted by a landowner to a grantee allowing the
use of private land for stormwater management purposes.
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.
The process by which the surface of the land, including channels,
is worn away by water, wind or chemical action.
A plan for a project site which identifies BMPs to minimize
accelerated erosion and sedimentation.
Any act by which earth, sand, gravel, rock or any other similar
material is cut into, dug, quarried, uncovered, removed, displaced
or relocated and shall include the conditions resulting therefrom.
The initial condition of a project site prior to the proposed
construction. If the initial condition of the site is undeveloped
land, the land use shall be considered as meadow unless the natural
land cover is proven to generate lower curve numbers.
An irrevocable letter of credit with a federal or commonwealth
lending institution, a corporate surety bond from a bonding company
authorized to do business within the commonwealth or such other guaranty
approved by the Solicitor in an amount approved by the Township Engineer.
The final vertical elevation of the ground after development.
Floodway Maps more fully described in the Zoning Ordinance.[1]
A vertical distance between the elevation of the design high
water and the top of a dam, levee, tank, basin or diversion swale.
The space is required as a safety margin in a pond or basin.
A slope, usually of a road, channel or natural ground specified
in percent and shown on plans as specified herein.
Low-growing plant materials planted and growing in such a
manner so as to conceal the earth surface.
Replenishment of existing natural underground water supplies.
Those surfaces which do not absorb rain. All buildings, parking
areas, driveways, roads, sidewalks and any areas in concrete, asphalt
and packed stone shall be considered impervious surfaces within this
definition. In addition, all areas determined by the Township Engineer
to be impervious within the meaning of this definition will also be
classed as impervious surfaces.
A retention or detention basin designed to retain stormwater
runoff and release it at a controlled rate.
A structure designed to direct runoff into the ground (e.g.,
seepage pits, seepage trench).
An in situ test performed in accordance with the current
requirements of the DEP by a qualified soil scientist or geotechnical
engineer to determine the permeability or percolation capacity of
an area for use in designing any infiltration BMPs.
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.
The Manager of Skippack Township, Montgomery County, Pennsylvania,
or other person so designated by the Board of Supervisors.
A computation to determine stormwater velocity according
to the formula:
|
V
|
=
|
1.486 R2/3 S1/2
| ||
|
n
| ||||
|
Where
| ||||
|
V
|
=
|
Velocity in feet per second.
| ||
|
R
|
=
|
Hydraulic radius, equal to the net effective
area (A) divided by the wetted perimeter (W. P.):
| ||
|
R
|
=
|
A
| ||
|
W.P.
| ||||
|
The wetted perimeter is the linear feet of the
drainage facility cross section which is wetted by the water.
| ||||
|
S
|
=
|
The slope of the energy line (for approximation,
use water surface slope in wetted stream and stream bed slope in dry
stream).
| ||
|
n
|
=
|
The roughness coefficient.
| ||
The maximum expected quantity of water arriving at a particular
location.
National Pollutant Discharge Elimination System, the federal
government's system for issuance of permits under The Clean Water
Act, whose administration is delegated to DEP 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 drainage ways, swales, streams, ditches and canals.
Points of water disposal from a stream, river, lake, tidewater
or artificial drain.
The maximum rate of stormwater runoff from a specific storm
event.
An individual, partnership, public or private association
or corporation or a governmental unit, public utility or any other
legal entity whatsoever which is recognized by law as the subject
of rights and duties.
A culvert, closed conduit or similar structure (including
appurtenances) that conveys stormwater.
The specific area of land where any regulated earth disturbance
activities in the Township are planned, conducted or maintained.
A calculation utilized to determine the maximum expected
discharge (peak flow) from areas less than 200 acres, or other area
as may be approved by the Township Engineer, according to the formula:
|
Q
|
=
|
CIA
| |
|
Where:
| |||
|
Q
|
=
|
The maximum expected discharge in cubic feet
per second.
| |
|
C
|
=
|
The runoff factor expressed as a percent of
the total water falling on an area.
| |
|
I
|
=
|
The rate of rainfall for the time of concentration
of the drainage area in inches per hour for a given storm frequency.
| |
|
A
|
=
|
The drainage area expressed in acres.
| |
A copy of an approved BMP operations and maintenance plan
which contains the original required endorsements of the Township
and which is intended to be recorded with the Montgomery County Recorder
of Deeds.
Earth disturbance activities on land which has previously
been disturbed or developed.
Earth disturbance activity of 5,000 square feet or greater.
This includes earth disturbance on any portion of, part or during
any state of a larger common plan of development. This only includes
road maintenance activities involving 25 acres or more of earth disturbance.
A reservoir, formed from soil or other material, which is
designed to permanently retain a certain amount of stormwater from
a catchment area and which also may be designed to temporarily detain
additional stormwater runoff from the catchment area or fresh water
from streams.
The average interval, in years, within which a storm event
of a given magnitude can be expected to recur. For example, the twenty-five-year
return period rainfall would be expected to recur on the average once
every 25 years.
A vertical pipe extending from the bottom of a pond that
is used to control the discharge rate from the pond for a specified
design storm.
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.
Any part of precipitation that flows over the land surface.
That portion of a total volume of water which can be expected
to flow off a particular surface.
A barrier, dam or retention or detention basin located and
designed to retain rock, sand, gravel, silt or other material transported
by water.
The placement, discharge or any other introduction of sediment
into the waters of the commonwealth occurring from the failure to
design, construct, implement or maintain control measures and control
facilities in accordance with the requirement of this chapter.
The process by which mineral or organic matter is accumulated
or deposited by the movement of water or gravity.
An area of excavated earth filled with loose stone or similar
coarse material into which surface water is directed for infiltration
into the ground.
A conveyance or system of conveyances (including roads with
drainage systems, Township streets, catch basins, curbs, gutters,
ditches, man-made channels or storm drains) primarily used for collecting
and conveying stormwater runoff.
Runoff that flows over the ground surface as a thin, even
layer, not concentrated in a channel.
A lot, tract or parcel of land or a series of lots, tracts
or parcels of land joined together.
The face of an embankment or cut section; any ground whose
surface makes an angle with the plane of the horizon. Slopes are usually
expressed in a percentage based upon vertical difference in feet per
100 feet of horizontal distance.
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).
A classification of soils by 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.
The Solicitor of Skippack Township, Montgomery County, Pennsylvania.
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.
As defined under state regulations (protection of designated and existing uses, See 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 is listed in Chapter 93. These uses must be protected and maintained under state regulations.
"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.
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.
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."
Steep slopes, which shall be defined as areas having a slope
of 20% percent or greater as identified on a field-generated topographic
plan prepared by a registered civil engineer or registered surveyor,
using two-foot-interval contours and having an elevation difference
of at least eight feet.
A system of pipes and/or open channels that convey intercepted
runoff and stormwater from other sources, but excludes domestic sewage
and industrial wastes.
The surface runoff generated by precipitation reaching the
ground surface.
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.
The removal of vegetation, including trees and topsoil. The
normal process of gardening or property maintenance shall be excluded
from this definition
The smallest drainage unit of a watershed for which stormwater
management criteria have been established in the stormwater management
plan.
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
water, or parts thereof, whether natural or artificial, within or
on the boundaries of this commonwealth.
A low-lying stretch of land which gathers or carries surface
water runoff.
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.
A factor used in conjunction with the application of the
rational method which specifies a lag factor between the time of concentration
(Tc) and the peak runoff for a given watershed. For purposes of this
chapter, Tp shall equal three for the standard rational method, five
for the modified rational method and seven for the DeKalb rational
method.
Skippack Township, Montgomery County, Pennsylvania.
A registered landscape architect designated by the Board
of Supervisors to perform the duties of arborist as herein specified.
A registered engineer designated by the Board of Supervisors
to perform the duties of engineer as herein specified.
A boundary line marking the outer edges of the branches of
a tree.
An area 15 feet radially from the trunk of the tree to be
retained or the distance from the trunk to the tree dripline, whichever
is greater, in which no construction activity shall occur. Where there
is a group of trees or woodlands, the tree protection zone shall be
the aggregate of the protection zones for the individual trees.
A channel or conveyance of surface water, such as a stream
or creek, having 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, whether natural or artificial.
Those areas that are inundated or saturated by surface or
ground water 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.
