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 words "shall" and "must" are mandatory; the words "may" and "should"
are permissive.
(4)
The words "Supervisors" or "Board" or "governing body" shall refer
to the Board of Supervisors of Upper Hanover Township.
(5)
The words "Zoning Hearing Board" shall refer to the Zoning Hearing
Board of Upper Hanover Township.
(6)
The words "Stormwater Ordinance" mean the Upper Hanover Township
Stormwater Management Ordinance.
(7)
Terms not defined in this article shall be interpreted according
to common usage or as the context may imply.
B.
ACCELERATED EROSION
APPLICANT
BEST MANAGEMENT PRACTICE (BMP)
BEST MANAGEMENT PRACTICE OPERATIONS AND MAINTENANCE PLAN
BIORETENTION
CAPTURE/REUSE
CISTERN
CLOSED DEPRESSION
CONCENTRATED DRAINAGE DISCHARGE
CONSERVATION DISTRICT
CONSTRUCTED WETLANDS
CULVERT
DAM
DEP
DESIGN STORM
DETENTION BASIN
DEVELOPER
DEVELOPMENT SITE (SITE)
DIFFUSED DRAINAGE
DIRECT RECHARGE BMP
DRAINAGE EASEMENT
DRAINAGE PLAN
EARTH-DISTURBANCE ACTIVITY
EROSION
EVAPOTRANSPIRATION BMP
EXISTING USES
FILL
FILTER STRIPS
FREEBOARD
GROUNDWATER RECHARGE
HOT-SPOT LAND USES
HYDROLOGIC ENGINEERING CENTER – HYDROLOGIC MODELING SYSTEM
(HEC-HMS)
HYDROLOGIC SOIL GROUP (HSG)
IMPERVIOUS SURFACE (IMPERVIOUS COVER)
INFILTRATION PRACTICE
LAND DEVELOPMENT
(1)
(a)
(b)
(2)
(3)
(a)
(b)
LANDOWNER
LOCAL RUNOFF CONVEYANCE FACILITIES
LOW-IMPACT DEVELOPMENT
MAIN STEM (MAIN CHANNEL)
MANNING EQUATION (MANNING FORMULA)
MARYLAND STORMWATER DESIGN MANUAL
MINIMUM DISTURBANCE/MINIMUM MAINTENANCE PRACTICES (MD/MM)
MUNICIPALITY
NPDES
NRCS
OIL/WATER SEPARATOR
OUTFALL
PEAK DISCHARGE
PERSON
POINT SOURCE
PUBLIC WATER SUPPLIER
PUBLIC WATER SYSTEM
RATIONAL METHOD
REACH
REGULATED ACTIVITIES
REGULATED EARTH-DISTURBANCE ACTIVITY
RELEASE RATE
RETENTION BASIN
RETURN PERIOD
ROAD MAINTENANCE
RUNOFF
SEDIMENT TRAPS/CATCH BASIN SUMPS
SEEPAGE PIT/SEEPAGE TRENCH
SEPARATE STORM SEWER SYSTEM
SHEET FLOW
SOIL-COVER-COMPLEX METHOD
SPILL PREVENTION AND RESPONSE PROGRAM
STATE WATER QUALITY REQUIREMENTS
(1)
(2)
(3)
STORAGE INDICATION METHOD
STORM DRAINAGE PROBLEM AREAS
STORM SEWER
STORMWATER
STORMWATER FILTERS
STORMWATER MANAGEMENT PLAN
STREAM
SUBAREA
SUBDIVISION
SURFACE WATERS OF THE COMMONWEALTH
SWALE
TRASH/DEBRIS COLLECTORS
VEGETATED BUFFERS
VEGETATED ROOFS
VEGETATED SWALES
WAIVER REQUEST
WATERCOURSE
WATER QUALITY INSERTS
WATER QUALITY VOLUME (WQV)
WATERSHED
WET DETENTION BASINS/PONDS
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 human activities and natural processes, at a rate greater
than would occur because of the natural processes alone.
A person who has filed an application for approval to engage in any regulated activities as defined in § 415-5.
Activities, facilities, measures or procedures used to manage stormwater quantity and quality impacts from the regulated activities listed in § 415-5, to meet state water quality requirements, to promote groundwater recharge and to otherwise meet the purposes of this chapter.
Documentation, included as part of a drainage plan, detailing
the proposed BMPs, how they will be operated and maintained and who
will be responsible.
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.
Stormwater management techniques such as cisterns and rain
barrels which direct runoff into storage devices, surface or subsurface,
for later reuse, such as for irrigation of gardens and other planted
areas.
An underground reservoir or tank for storing rainwater.
A distinctive bowl-shaped depression in the land surface.
It is characterized by internal drainage, varying magnitude, and an
unbroken ground surface.
Stormwater runoff leaving a property via a point source.
The Montgomery County Conservation District.
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.
A pipe, conduit or similar structure including appurtenant
works which carries surface water.
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 Pennsylvania Department of Environmental Protection.
The depth and time distribution of precipitation from a storm
event measured in probability of occurrence (e.g., one-hundred-year
storm) and duration (e.g., twenty-four-hour) and used in computing
stormwater management control systems.
A basin designed to retard stormwater runoff by temporarily
storing the runoff and releasing it at a predetermined rate.
A person, 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.
See "sheet flow."
A BMP which directs runoff to an underground infiltration
surface. Examples include infiltration trenches, seepage beds, and
dry wells such that nearly all runoff becomes recharge to groundwater.
A right granted by a landowner to a grantee, allowing the
use of private land for stormwater management purposes.
The documentation of the proposed stormwater quantity and quality management controls to be used for a given development site, including a BMP operations and maintenance plan, the contents of which are established in § 415-24.
A construction or other human activity which disturbs the
surface of the 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.
The removal of soil particles by the action of water, wind,
ice, or other geological agents.
A BMP which provides opportunity for runoff evaporation and
transpiration by vegetation. Examples include bioretention and surface
infiltration basins.
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 § 93.1).
Man-made deposits of natural soils or rock products and waste
materials.
See "vegetated Buffers."
The incremental depth in a stormwater management structure,
provided as a safety factor of design, above that required to convey
the design runoff event.
Replenishment of existing natural underground water supplies.
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 Appendix
F.[1]
The computer-based hydrologic modeling technique developed
by the United States Army Corps of Engineers and adapted to the Perkiomen
Creek Headwaters for the Act 167 Plan. The model was "calibrated"
to reflect actual flow values by adjusting key model input parameters.
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)
of the United States Department of Agriculture 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 permeable as the HSG varies from A to D.
A surface which prevents the percolation of water into the
ground.
A practice designed to allow runoff an opportunity to infiltrate
into the ground, e.g., french drain, seepage pit, seepage trench,
or bioretention area.
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 of
tenure; or
The division or allocation of land or space between or among
two or more existing or prospective occupants by means of, or for
the purpose of, streets, common areas, leaseholds, condominiums, building
groups or other features.
A subdivision of land.
Except that the following activities shall not be considered
land development:
The conversion of an existing single-family 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.
The legal or beneficial owner or owners of land including
the holder of an option or contract to purchase (whether or not such
option or contract is subject to any condition), a lessee if they
are authorized under the lease to exercise the rights of the landowner,
or other person having a proprietary interest in land.
Any natural channel or man-made conveyance system which has
the purpose of transporting runoff from the site to the main stem.
A development approach that promotes practices that will
minimize post-development runoff rates and volumes, thereby minimizing
needs for artificial conveyance and storage facilities. Site design
practices include preserving natural drainage features, minimizing
impervious surface area, reducing the hydraulic connectivity of impervious
surfaces and protecting natural depression storage.
Any stream segment or other conveyance used as a reach in
the Perkiomen Creek Headwaters hydrologic model.
A method for calculation of velocity of flow (e.g., feet
per second) and flow rate (e.g., cubic feet per second) in open channels
based upon channel shape, roughness, depth of flow and slope. "Open
channels" may include closed conduits so long as the flow is not under
pressure.
A stormwater design manual written by the Maryland Department
of the Environment and the Center for Watershed Protection. As of
January 2004, the manual can be obtained through the following web
site: www.mde.state.md.us.
Site design practices 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.
These criteria may vary by community context as well as by type of
development being proposed. Additionally, MD/MM shall include provisions
(e.g., deed restrictions, conservation easements) to protect these
areas from future disturbance and from application of fertilizers,
pesticides, and herbicides.
Upper Hanover Township, Montgomery County, Pennsylvania.
National Pollutant Discharge Elimination System.
Natural Resources Conservation Service, United States Department
of Agriculture (formerly the Soil Conservation Service).
A structural mechanism designed to remove free oil and grease
(and possibly solids) from stormwater runoff.
"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.
The maximum rate of flow of stormwater runoff at a given
location and time resulting from a specified storm event.
An individual, partnership, public or private association
or corporation, firm, trust, estate, municipality, governmental unit,
public utility or any other legal entity whatsoever which is recognized
by law as the subject of rights and duties.
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.
A person who owns or operates a 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.)
A method of runoff calculation using a standardized runoff
coefficient, acreage of tract, and rainfall intensity that is determined
by return period and by the time necessary for the entire tract to
contribute runoff.
Any of the natural or man-made runoff conveyance channels
used for watershed runoff modeling purposes to connect the subareas
and transport flows downstream.
Any earth-disturbance activities or any activities that involve the alteration or development of land in a manner that may affect stormwater runoff and that are governed by this chapter as specified in § 415-5.
Activity involving earth disturbance, other than agricultural
plowing and tilling, subject to regulation under 25 Pa. Code 92, 25
Pa. Code 102, or the Clean Streams Law.[2]
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.
A structure in which stormwater is stored and not released
during the storm event. Retention basins do not typically have an
outlet to other downstream conveyance features such as channels, storm
sewer, or other surface waters. Generally, these features empty via
recharge and must infiltrate stored water in no more than four days.
These features may have an emergency spillway or other overflow device
for large events.
The average interval in years over which an event of a given
magnitude can be expected to recur. For example, the twenty-five-year
return period rainfall or runoff event would be expected to recur
on the average once every 25 years.
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.
That part of precipitation which flows over the land.
Chambers which provide storage below the outlet in a storm
inlet to collect sediment, debris and associated pollutants, typically
requiring periodic cleanout.
An area of excavated earth filled with loose stone or similar
material and into which surface water is directed for infiltration
into the ground.
A conveyance or system of conveyances (including roads with
drainage systems, municipal streets, catch basins, curbs, gutters,
ditches, man-made channels or storm drains) primarily used for collecting
and conveying stormwater runoff.
Stormwater runoff flowing in a thin layer over the ground
surface.
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."
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.
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 fishes" 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 stream bank, streambed
and structural integrity of the waterway, to prevent these impacts.
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.
Areas which lack adequate stormwater collection and/or conveyance
facilities and which present a hazard to persons or property as determined
by the municipality.
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.
The surface runoff generated by precipitation reaching the
ground surface.
Any number of structural mechanisms such as multi-chamber
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.
The plan for managing stormwater runoff adopted by Montgomery
County for the Perkiomen Creek Headwaters Watershed as required by
the Act of October 4, 1978, P.L. 864 (Act 167), as amended, and known
as the "Stormwater Management Act."[3]
A watercourse.
The smallest unit of watershed breakdown for hydrologic modeling
purposes for which the runoff control criteria have been established
in the stormwater management plan.
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 and new
street or easement of access or any residential dwelling, shall be
exempted.
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. See also "vegetated swale."
Racks, screens or other similar devices installed in a storm
drainage system to capture coarse pollutants (trash, leaves, etc.).
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 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 earthen channels designed to convey and possibly
treat stormwater. As water quality BMPs, these are broad, shallow,
densely vegetated, earthen channels designed to treat stormwater through
infiltration, evapotranspiration, and sedimentation. Swales should
be gently sloping with low-flow velocities to prevent erosion. Check
dams may be added to enhance performance.
A written request for a waiver alleging that the provisions
of this chapter inflict unnecessary hardship upon the applicant. A
waiver does not apply to and is not available from the water quality
provisions of this chapter and should not be granted.
Any channel of conveyance of surface water having defined
bed and banks, whether natural or artificial, with perennial or intermittent
flow.
Any number of commercially available devices that are inserted
into storm inlets to capture sediment, oil, grease, metals, trash,
debris, etc.
The increase in volume on a development site associated with
a two-year, twenty-four-hour storm event.
The entire region or area drained by a river or other body
of water, whether natural or artificial.
Basins that provide for 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.
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, including
swamps, marshes, bogs, fens, and similar areas.
[1]
Editor's Note: Said appendix is included as an attachment to this chapter.
[2]
Editor's Note: See 35 P.S. § 691.1 et seq.
[3]
Editor's Note: See 32 P.S. 680.1 et seq.
