[Ord. 2011-415, 5/5/2011, § 3]
These regulations shall be known as and referred to as the "Township
of Cranberry Stormwater Management Regulations" in accordance with
the Butler County Act 167 Stormwater Management Plan.
[Ord. 2011-415, 5/5/2011, § 3]
The general purposes of these regulations are to promote health, safety, and welfare within Cranberry Township, Butler County, by minimizing the harms and maximizing the benefits described in § 17-102 of Chapter 17 through provisions intended to:
A.
Meet legal water quality requirements under state law, including
regulations at 25 Pa. Code Chapter 93 to protect, maintain, reclaim,
and restore the existing and designated uses of the waters of the
commonwealth.
B.
Manage accelerated runoff and erosion and sedimentation problems
close to their source by regulating activities that cause these problems.
C.
Preserve the natural drainage systems as much as possible.
D.
Maintain groundwater recharge to prevent degradation of surface and
groundwater quality and to otherwise protect water resources.
E.
Maintain existing flows and quality of streams and watercourses.
F.
Preserve and restore the flood-carrying capacity of streams and prevent
scour and erosion of stream banks and streambeds.
G.
Manage stormwater impacts close to the runoff source with a minimum
of structures and a maximum use of natural processes.
H.
Provide procedures, performance standards, and design criteria for
stormwater planning and management.
I.
Provide proper operations and maintenance of all temporary and permanent
stormwater management facilities and best management practices (BMPs)
that are constructed and implemented.
J.
Provide standards to meet the NPDES permit requirements.
K.
For MS4 permittees, implement an illegal discharge detection and
elimination program in MS4 permanent urbanized areas to address non-stormwater
discharges into Cranberry Township's separate storm sewer system.
L.
Inadequate management of accelerated runoff stormwater resulting
from development throughout a watershed increases runoff volumes,
flows and velocities, contributes to erosion and sedimentation, overtaxes
the carrying capacity of streams and storm sewers, greatly increases
the cost of public facilities to carry and control stormwater, undermines
floodplain management and flood control efforts in downstream communities,
reduces groundwater recharge, threatens public health and safety,
and increases nonpoint source pollution of water resources.
[Added by Ord. No. 2022-506, 1/27/2022]
M.
A comprehensive
program of stormwater management (SWM), including reasonable regulation
of development and activities causing accelerated runoff, is fundamental
to the public health, safety, and welfare and the protection of people
of the commonwealth, their resources and the environment.
[Added by Ord. No. 2022-506, 1/27/2022]
N.
Stormwater
is an important water resource that provides groundwater recharge
for water supplies and supports the base flow of streams.
[Added by Ord. No. 2022-506, 1/27/2022]
O.
The use
of green infrastructure and low impact development (LID) are intended
to address the root cause of water quality impairment by using systems
and practices which use or mimic natural processes to: 1) infiltrate
and recharge, 2) evapotranspire, and/or 3) harvest and use precipitation
near where it falls to earth. Green infrastructure practices and LID
contribute to the restoration or maintenance of predevelopment hydrology.
[Added by Ord. No. 2022-506, 1/27/2022]
P.
Federal
and state regulations require certain municipalities to implement
a program of stormwater controls. These municipalities are required
to obtain a permit for stormwater discharges from their separate storm
sewer systems under the National Pollutant Discharge Elimination System
(NPDES) program.
[Added by Ord. No. 2022-506, 1/27/2022]
[Ord. 2011-415, 5/5/2011, § 3]
The Township shall be responsible for the administration, enforcement
and interpretation of the Stormwater Management Regulations.
[Ord. 2011-415, 5/5/2011, § 3]
1.
These regulations shall be applicable to the construction of all
public and private improvements in the Township as follows.
A.
In Cranberry Township all regulated activities and all activities
that may affect stormwater runoff, including land development and
earth disturbance activity, are subject to regulation by this Part.
B.
Cranberry Township is empowered to regulate these activities by the
authority of the Act of October 4, 1978, P.L. 864 (Act 167), 32 P.S. § 680.1
et seq., as amended, the Storm Water Management Act, and the Public
Private Improvement Code.
D.
Earth disturbance activities and associated stormwater management
controls are also regulated under existing state law and implementing
regulations. This Part shall operate in coordination with those parallel
requirements; the requirements of this Part shall be no less restrictive
in meeting the purposes of this Part than state law.
E.
"Regulated activities" are any earth disturbance activities or any
activities that involve the alteration or development of land in a
manner that may affect stormwater runoff. "Regulated activities" include,
but are not limited to, the following listed items:
(1)
Earth disturbance activities.
(2)
Land development.
(3)
Subdivision.
(4)
Construction of new or additional impervious or semipervious
surfaces.
(5)
Construction of new buildings or additions to existing buildings.
(6)
Diversion or piping of any natural or man-made stream channel.
(7)
Installation of stormwater management facilities or appurtenances
thereto.
(8)
Installation of stormwater BMPs.
2.
See § 17-350.7C(1)(c) of this Part for exemption/modification
criteria.
[Ord. 2011-415, 5/5/2011, § 3]
Public and private improvements constructed by any person or entity, including a developer, shall be constructed in accordance with Part 3 of this chapter.
[Ord. 2011-415, 5/5/2011, § 3]
All construction of public and private improvements in the Township
by developers shall be conducted in accordance with this Part.
A.
Notice Prior to Start of Work. In order that the Township may provide
proper inspection and emergency services during construction, the
developer shall file with the Township a notice of commencement in
the form set forth in Part 3 not less than two days prior to the start
of work and shall also submit the following:
B.
Supervision and Superintendence.
(1)
The developer shall supervise and direct the work and be solely
responsible to see that the work is done in accordance with the construction
standards and specifications.
(2)
The developer shall have available at all times while construction
is continuing a competent superintendent who may be contacted during
an emergency. The superintendent will be the developer's representative
at the site and shall have authority to act on behalf of the developer.
All communications given to the superintendent shall be as binding
as if given to the developer. If the superintendent is replaced, the
developer shall give written notice thereof to the Township immediately.
(3)
The developer shall be fully responsible for the acts and omissions
of the contractors, subcontractors, persons and organizations directly
or indirectly in his employ.
C.
Site Appearance. The developer shall keep the site free from accumulation
of waste materials, rubbish and other debris resulting from the work.
At the completion of the work, the developer shall remove all waste
materials, rubbish and debris from and about the site as well as all
tools, construction equipment and machinery, and surplus materials
and shall leave the site clean.
D.
Parking. No construction vehicles, vehicles of construction employees,
equipment, materials or supplies shall encroach onto a public street.
In the case where there is a private street or proposed public street
not yet accepted by the Township, the developer shall maintain an
eighteen-foot unobstructed clear path on such street for emergency
vehicle purposes.
E.
Hours of Construction. The operation of heavy construction or excavation
machinery, including, but not limited to, bulldozers, high-lifts,
backhoes, trucks, power shovels, pumps and jack hammers, and the operation
of equipment such as saws and drills or any other type of machinery
in conjunction with the construction of public and private improvements
which causes noise sufficient to disturb the peace and general tranquility
of the general public shall be prohibited in the entire Township between
the hours of 9:00 p.m. and 7:00 a.m., Monday through Saturday, and
all day Sunday.
F.
Dust Control. The developer shall maintain the site so as to control
the dust. The developer shall employ measures necessary to control
dust. At the Township's direction, the Township may require routine
maintenance of the site for dust control if, in the opinion of the
Township, the developer is not maintaining the site in a reasonable
manner.
G.
Responsibility for Compliance. The developer shall have the sole
responsibility to comply with all federal, state, and local laws,
and the Township disclaims any duty to enforce any violation of such
laws or inform the developer of noncompliance.
H.
Notwithstanding any provision(s) of this Part, including exemptions,
any landowner or any person engaged in the alteration or development
of land which may affect stormwater runoff characteristics shall implement
such measures as are reasonably necessary to prevent injury to health,
safety, or other property. Such measures also shall include actions
as are required to manage the rate, volume, direction, and quality
of resulting stormwater runoff in a manner which otherwise adequately
protects health, property, and water quality.
[Ord. 2011-415, 5/5/2011, § 3]
A Township road occupancy permit is required for the installation
of any utilities or stormwater infrastructure within an existing public
street in accordance with the procedures and requirements set forth
in this Code.
[Ord. 2011-415, 5/5/2011, § 3]
1.
It shall be unlawful for any developer or public utility company
to construct public or private improvements regulated by this Part,
or cause the same to be done, in conflict with or in violation of
any of the provisions of this Part.
2.
Notice of Violation. The Township shall serve a notice of violation
or order on the developer or utility company responsible for the violation
of the provisions of this Part or of the plans approved thereunder.
Such order shall direct the discontinuance of the illegal action or
condition and the abatement of the violation.
A.
In the event that a person fails to comply with the requirements
of this Part, an approved SWM site plan, or fails to conform to the
requirements of any permit or approval issued hereunder, the Township
shall provide written notification of the violation. Such notification
shall set forth the nature of the violation(s) and establish a time
limit for correction of these violation(s).
B.
Failure to comply within the time specified shall subject such person
to the penalties provisions of this Part. All such penalties shall
be deemed cumulative and shall not prevent the Township from pursuing
any and all other remedies. It shall be the responsibility of the
owner of the real property on which any regulated activity is proposed
to occur, is occurring, or has occurred to comply with the terms and
conditions of this Part.
3.
Any person who shall violate a provision of this Part or who shall
fail to comply with any requirement thereof, upon conviction thereof
in an action brought before a district judge in the manner provided
for the enforcement of summary offenses under the Pennsylvania Rules
of Criminal Procedure, shall be sentenced to pay a fine of not more
than $1,000 plus costs and, in default of payment of said fine and
costs, to a term of imprisonment not to exceed 90 days. Each day that
a violation of this Part continues or each section of this Part which
shall be found to have been violated shall constitute a separate offense.
A.
In addition, the Township, through its solicitor, may institute injunctive,
mandamus, or any other appropriate action or proceeding at law or
in equity for the enforcement of this Part. Any court of competent
jurisdiction shall have the right to issue restraining orders, temporary
or permanent injunctions, mandamus, or other appropriate forms of
remedy or relief.
4.
Abatement of Violation. The imposition of the penalties herein prescribed
shall not preclude the Township from instituting appropriate action
to prevent unlawful construction or to restrain, correct or abate
a violation or to stop an illegal act.
[Ord. 2011-415, 5/5/2011, § 3]
1.
Notice to Stop Work. Upon notice from the Township that work on the
installation of public or private improvements is being prosecuted
contrary to the provisions of this Part, such work shall be immediately
stopped. The stop-work order shall be in writing and shall be given
to the developer or to the person doing the work. The stop-work order
shall state the conditions under which the work may be resumed.
2.
Unlawful Continuance. Any person who shall continue any work in or
about a work site after having been served with a stop-work order,
except such work as that person is directed to perform to remove a
violation or unsafe conditions, shall be liable to the violations
and penalties set forth herein.
[Ord. 2011-415, 5/5/2011, § 3]
The procedure for acceptance of public improvements shall be in accordance with the Subdivision and Land Development Ordinance [Chapter 22]. The Township is under no obligation to accept such dedication, and acceptance may occur only by action of the governing body of the Township.
[Ord. 2011-415, 5/5/2011, § 3]
This Part may be amended by action of the Supervisors in accordance with this Public and Private Improvements Code; however, the construction standards in Part 3 of this chapter as they pertain to any particular public improvement may be amended by motion of the Supervisors upon recommendation of the Engineer and Township Manager.
[Ord. 2011-415, 5/5/2011, § 3]
1.
Should there arise any dispute between the developer or the Township
with regard to any provisions of this Part, the developer and Township
may elect to use the provisions of this section to mediate such dispute.
Participation in mediation shall be wholly voluntary. The appropriateness
of mediation shall be determined by the particulars of each case and
the willingness of the parties to negotiate.
2.
Parties agreeing to enter into mediation shall first enter into a
written mediation agreement containing at least the following minimum
provisions.
A.
Identification of the selected mediator who, at a minimum, shall
have a working knowledge of municipal zoning and subdivision procedures
and engineering practices. The mediator shall have demonstrated skills
in mediation.
B.
Time frame in which the mediation will be conducted and completed.
C.
Provisions for suspension of time limits, if necessary, for applications
subject to the same in regards to subdivision, land development, PRD
or other application or procedures pursuant to the Pennsylvania Municipalities
Planning Code, 53 P.S. § 10101 et seq.
D.
Identification of all parties and affording them the opportunity
to participate.
E.
Subject to legal restraints, determining whether the mediation sessions
or parts thereof shall be open to the public.
F.
Identification as to whether the results of such mediation shall
be binding upon the parties.
3.
Funding
for mediation shall be born equally by the Township and the developer.
4.
Mediated solutions shall be in writing and signed by the parties
and become subject to review and approval by the appropriate decisionmaking
body when necessary.
5.
No offers or statements made in the mediation sessions, excluding
the final written mediated agreement, shall be admissible as evidence
in any subsequent judicial or administrative proceedings.
[Ord. 2011-415, 5/5/2011, § 3]
No subdivision and/or land development shall be finally approved unless the public and private improvements as shown on plans have been improved, constructed or installed as may be required by Chapter 22, Subdivision and Land Development. In lieu of the completion of any improvements required as a condition for the final approval of plans, the developer shall deposit with the municipality a financial security in an amount sufficient to cover the costs of such improvements which may be required in conformance with the requirements of the Pennsylvania Municipalities Planning Code. The deposit of financial security shall be in a format and amount as determined acceptable by the Township and in accordance with Chapter 22, Subdivision and Land Development, Part 3, Administration, § 22-305, Subsection 10.
[Ord. 2011-415, 5/5/2011, § 3]
1.
Neither the granting of any approval under this Part nor the compliance
with the provisions of this Part, or with any condition imposed by
a Township official hereunder, shall relieve any person from any responsibility
for damage to persons or property resulting therefrom, or as otherwise
imposed by law, nor impose any liability upon the Township for damages
to persons or property.
2.
The granting of a permit that includes any stormwater management
facilities shall not constitute a representation, guarantee or warranty
of any kind by the Township, or by an official or employee thereof,
of the practicability or safety of any structure, use or other plan
proposed, and shall create no liability upon or cause of action against
such public body, official or employee for any damage that may result
pursuant thereto.
[Ord. 2011-415, 5/5/2011, § 3]
[Ord. 2011-415, 5/5/2011, § 3]
1.
In the event that a person fails to comply with the requirements
of this Part, an approved SWM site plan, or fails to conform to the
requirements of any permit or approval issued hereunder, the Township
shall provide written notification of the violation. Such notification
shall set forth the nature of the violation(s) and establish a time
limit for correction of these violation(s).
2.
Failure to comply within the time specified shall subject such person
to the penalties provisions of this Part. All such penalties shall
be deemed cumulative and shall not prevent the Township from pursuing
any and all other remedies. It shall be the responsibility of the
owner of the real property on which any regulated activity is proposed
to occur, is occurring, or has occurred to comply with the terms and
conditions of this Part.
[Ord. 2011-415, 5/5/2011, § 3]
1.
The Township governing body is hereby authorized and directed to
enforce all of the provisions of this Part. The approved SWM site
plan shall be on file at the project site throughout the duration
of the construction activity. The Township or its designee may make
periodic inspections during construction.
2.
Adherence to Approved SWM Site Plan.
A.
It shall be unlawful for any person, firm, or corporation to undertake
any regulated activity on any property except as provided for by an
approved SWM site plan and pursuant to the requirements of this Part.
B.
It shall be unlawful to alter or remove any control structure required
by the SWM site plan pursuant to this Part.
C.
It shall be unlawful to allow a property to remain in a condition
that does not conform to an approved SWM site plan.
3.
The landowner or the owner's designee (including the municipality
for dedicated and owned facilities) shall inspect SWM BMPs, facilities
and/or structures installed under this Part according to the following
frequencies, at a minimum, to ensure the BMPs, facilities and/or structures
continue to function as intended: 1) annually; and 2) during or immediately
after the cessation of a ten-year or greater storm.
[Amended by Ord. No. 2022-506, 1/27/2022]
A.
The Township may require copies of the inspection reports, in a form
as stipulated by the Township.
B.
If such inspections are not conducted or inspection reports not submitted
as scheduled, the Township, or its designee, may conduct such inspections
and charge the owner appropriate fees. Nonpayment of fees may result
in a lien against the property.
C.
Inspections should be conducted during or immediately following precipitation
events. A written inspection report shall be created to document each
inspection. The inspection report shall contain the date and time
of the inspection, the individual(s) who completed the inspection,
the location of the BMP, facility or structure inspected, observations
on performance, and recommendations for improving performance, if
applicable. Inspection reports shall be submitted to the municipality
within 30 days following completion of the inspection. Annual inspection
by landowners shall be completed and reported to the Township between
January to April.
D.
Inspections regarding compliance with the SWM site plan are a responsibility
of the municipality.
4.
PADEP or its designees normally ensure compliance with any permits
issued, including those for stormwater management. In addition to
PADEP compliance programs, the Township or their Township assignee
may inspect all phases of the installation of temporary or permanent
stormwater management facilities.
5.
Prior to conducting such inspections, the Township shall inform the
owner of its intent to conduct such inspections. The owner shall be
given 30 days to conduct required inspections and submit the required
inspection reports to the Township.
[Ord. 2011-415, 5/5/2011, § 3; amended by Ord. No. 2022-506, 1/27/2022]
1.
Any person aggrieved by any action of the municipality or its designee,
relevant to the provisions of this Part, may appeal to the municipality
within 30 days of that action.
2.
Any person aggrieved by any decision of the municipality, relevant
to the provisions of this Part, may appeal to the County Court of
Common Pleas in the county where the activity has taken place within
30 days of the municipality's decision.
[Ord. 2011-415, 5/5/2011, § 3]
As used in this Part, the following terms shall have the meanings
indicated:
The removal of the surface of the land through the combined
action of human activity and natural processes at 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, 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;
changing of surface conditions by causing the surface to be more or
less impervious; land disturbance.
A landowner or developer, as hereinafter defined, who has
filed an application for development, including his heirs, successors
and assigns.
A drawing showing the final as-built location, elevation
and/or depth, size and materials of all completed public and private
improvements as well as all easements.
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 Part. Stormwater BMPs are commonly
grouped into one of two broad categories or measures: nonstructural
or structural. "Nonstructural BMPs" are measures referred to as operational
and/or behavior-related practices that attempt to minimize the contact
of pollutants with stormwater runoff whereas "structural BMPs" are
measures the 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.
That paved road surface from front of curb to front of curb.
The widening, deepening, and headward cutting of small channels
and waterways due to erosion caused by moderate to large floods.
An underground reservoir or tank used for storing rainwater.
The Butler County Conservation District. The Butler County
Conservation District has the authority under a delegation agreement
executed with the Department of Environmental Protection to administer
and enforce all or a portion of the regulations promulgated under
25 Pa. Code Chapter 102.
The construction standards for streets, stormwater management
facilities, sanitary sewer systems, pedestrian circulation, driveways,
parking areas, fire hydrants, guiderails, cable TV and other facilities
as set forth in this Part.
Any structure not classified as a bridge that provides an
opening under the roadway.
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.
[Added by Ord. No. 2022-506, 1/27/2022]
The agent of this Township and/or agent of the governing
body involved with the administration, review or enforcement of any
provisions of this Part by contract or memorandum of understanding.
Anticipated posted speed limit plus five miles per hour.
The magnitude and temporal distribution of precipitation
from a storm event measured in probability of occurrence (e.g., a
twenty-five-year storm) and duration (e.g., 24 hours), used in the
design and evaluation of stormwater management systems. Also see "return
period."
A stormwater facility that collects and temporarily stores
surface runoff and releases it at a controlled rate. Detention basins
may be classified into the following categories:
NATURALIZED BASINA detention basin designed to completely drain following a storm event and which blends into the surrounding environment by being curvilinear in shape and using native plants to provide soil stabilization. (See Chapter 17.)
UNDERGROUND BASINDetention storage located in underground tanks or vaults designed to provide water quantity control through detention of stormwater runoff.
The volume of runoff that is captured and released into waters
of the commonwealth at a controlled rate.
Any landowner, not a public utility company, agent of such
landowner, including the landowner's contractor or resident or superintendent
or tenant with permission of such landowner, who constructs or causes
to be constructed any public or private improvements anywhere in the
Township not under a contract.
The specific area of land where any regulated activities
in the municipality are planned, conducted or maintained.
[Added by Ord. No. 2022-506, 1/27/2022]
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 all overland or pipe flow
from the site would be directed toward it.
A stormwater management facility designed to convey stormwater
runoff and shall include streams, channels, swales, pipes, conduits,
culverts, storm sewers, etc.
A right granted by a landowner to a grantee, allowing the
use of private land for stormwater management, drainage, or conveyance
purposes.
Any natural or artificial watercourse, trench, ditch, pipe,
swale, channel, or similar depression into which surface water flows.
A private area used exclusively for circulation and ingress
and egress to a street by the owner or owners or visitors of the lot.
All driveways shall meet the requirements of this Part.
A detention basin designed to completely drain following
a storm event.
A residential building containing one dwelling unit occupied
by one family and which is the only principal building on the lot.
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.
Any unforeseen circumstance that calls for immediate action.
The Township Engineer who is charged with the design and
inspection of the work, and with determining the quantities of materials
and labor to be paid for. During the execution of the work the Engineer
shall also be interpreted to mean the assistant, inspector, or other
representative acting within the authority given. The Engineer is
to be considered an agent of the Township.
The movement of soil particles by the action of water, wind,
ice, or other natural forces.
A plan that is designed to minimize accelerated erosion and
sedimentation.
Surface waters of high quality which satisfy Pa. Code Title
25, Environmental Protection, Chapter 93, Water Quality Standards,
93.4b(b) (relating to antidegradation).
The initial condition of a project site prior to the proposed
construction. If the initial condition of the site is undeveloped
land and not forested, the land use shall be considered as "meadow"
unless the natural land cover is documented to generate lower curve
numbers or Rational "C" coefficient.
The Federal Emergency Management Agency.
A corporate bond letter of credit or escrow account from a surety or a financial institution acceptable to the Township, naming the Township as obligee in forms specified in Part 3 of this chapter.
A temporary inundation of normally dry land areas.[1]
Any land area susceptible to inundation by water from any
natural source or delineated by applicable Department of Housing and
Urban Development, Federal Insurance Administration Flood Hazard Boundary,
mapped as being a special flood hazard area. Included are lands adjoining
a river or stream that have been or may be inundated by a one-hundred-year
flood. Also included are areas that comprise Group 13 soils, as listed
in Appendix A of the Pennsylvania Department of Environmental Protection
(PADEP) Technical Manual for Sewage Enforcement Officers (as amended
or replaced from time to time by PADEP).
The channel of a river or other watercourse and the adjacent
land areas that must be reserved in order to discharge the base flood
without cumulatively increasing the water surface elevation more than
one foot.
[Amended by Ord. 2015-454, 5/6/2015]
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, or diversion ridge.
The space is required as a safety margin in a tank, pond or basin.
Systems and practices that use or mimic natural processes
to infiltrate, evapotranspire or reuse stormwater on the site where
it is generated.
[Added by Ord. No. 2022-506, 1/27/2022]
Replenishment of existing natural underground water supplies.
A computer-based hydrologic modeling technique adapted to
the watershed(s) in Butler County for the Act 167 Plan. The model
has been calibrated by adjusting key model input parameters.
Surface water having quality that exceeds levels necessary
to support propagation of fish, shellfish, and wildlife and recreation
in and on the water by satisfying Pa. Code Title 25, Environmental
Protection, Chapter 93, Water Quality Standards, 93.4b(a).
Infiltration rates of soils vary widely and are affected
by subsurface permeability as well as surface intake rates. Soils
are classified into one of four HSGs (A, B, C, and D) according to
their minimum infiltration rate, which is obtained for bare soil after
prolonged wetting. The Natural Resource 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 interest may
be identified from a soil survey report from the local NRCS office
or the County Conservation District.
A surface that prevents the infiltration of water into the
ground. Impervious surface (or areas) includes, but is not limited
to: roofs, additional indoor living spaces, patios, garages, storage
sheds and similar structures, parking or driveway areas, and any new
streets and sidewalks. Any surface areas proposed to initially be
gravel or crushed stone shall be assumed to be 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.,
french drains, seepage pits, seepage trench, 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.
[Added by Ord. No. 2022-506, 1/27/2022]
Any of the following activities:
The improvement of one lot or two or more contiguous lots, tracts,
or parcels of land for any purposes 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.
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.
A subdivision of land.
The legal or beneficial owner or owners of a lot, including
the holder of an option or contract to purchase (whether or not such
option or contract is subject to any conditions), a lessee (if he
is authorized under the lease to exercise the rights of the landowner)
or other persons having a proprietary interest in the lot.
The width of the travel lane. Typically set at 11 feet when
painted with yellow and white lines.
An approach to land development that uses various land planning
and design practices and technologies to simultaneously conserve and
protect natural resource systems and reduce infrastructure costs.
LID still allows land to be developed, but in a cost-effective manner
that helps mitigate potential environmental impacts.
Any stream segment or other runoff conveyance facility used
as a reach in the Butler County Act 167 watershed hydrologic model(s).
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.
Cranberry Township, Butler County, Pennsylvania.
[Added by Ord. No. 2022-506, 1/27/2022]
The federal government's system for issuance of permits under
the Clean Water Act, which is delegated to PADEP in Pennsylvania.
A detention basin designed to completely drain following
a storm event and which blends into the surrounding environment by
being curvilinear in shape and using native plants to provide soil
stabilization.
Precipitation-Frequency Atlas of the United States, Atlas
14, Volume 2, US Department of Commerce, National Oceanic and Atmospheric
Administration, National Weather Service, Hydrometeorological Design
Studies Center, Silver Spring, Maryland (2004). NOAA's Atlas 14 can
be accessed at Internet address http://hdsc.nws.noaa.gov/hdsc/pfds/.
Pollution that enters a water body from diffuse origins in
the watershed and does not result from discernible, confined, or discrete
conveyances.
Natural Resource Conservation Service [previously Soil Conservation
Service (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
not under pressure.
Points of water disposal from a stream, river, lake, tidewater,
or artificial drain.
The Pennsylvania Department of Environmental Protection.
A public or private garage or a paved, open, off-street area
other than a driveway or street with adequate means of access, which
meets the requirements of this Part and which is used exclusively
for the parking of vehicles of occupants or visitors of the lot; however,
a driveway serving a single-family dwelling or which is for the exclusive
use of an individual dwelling unit in a residential building may be
used as a parking area.
Involves the use of impervious parking areas as temporary
impoundments with controlled release rates during rainstorms.
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.
Any area not defined as impervious.
A culvert, closed conduit, or similar structure (including
appurtenances) that conveys stormwater.
The Planning Advisory Commission of Cranberry Township.
Any discernible, confined, or 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 street, sidewalk, walkway, gutter, curb, sewer, water line,
driveway, parking area, streetlight, street sign, or related facility
to be operated and maintained by a private entity, but which must
comply with this Part.
The flood that may be expected from the most severe combination
of critical meteorological and hydrologic conditions that are reasonably
possible in any area. The PMF is derived from the probable maximum
precipitation (PMP) as determined on the basis of data obtained from
the National Oceanographic and Atmospheric Administration (NOAA).
The specific area of land where any regulated activities
in the Township are planned, conducted, or maintained.
A street, sidewalk, walkway, gutter, curb, sewer, water line,
streetlight, street sign or related facility to be dedicated to or
maintained by the Township and which must comply with this Part.
Any company subject to the jurisdiction of and control by
the Pennsylvania Public Utility Commission or franchised cable television
company.
Any person licensed by the Pennsylvania Department of State
or otherwise qualified by law to perform the work required by the
ordinance.
A rainfall-runoff relation used to estimate peak flow.
A drawing that provides surveyed engineering data of constructed
infrastructure.
Earth disturbance activities on land that has previously
been developed.
Any earth disturbance activities or any activities that involve
the alteration or development of land in a manner that may affect
stormwater runoff.
Activity involving earth disturbance subject to regulation
under 25 Pa. Code Chapter 92, Chapter 102, or the Clean Streams Law.[2]
Those subwatershed areas in which post-development flows
must be reduced to a certain percentage of predevelopment flows as
required to meet the plan requirements and the goals of Act 167.
An impoundment in which stormwater is stored and not released
during the storm event. Stored water may be released from the basin
at some time after the end of the storm.
The volume of runoff that is captured and not released directly
into the surface waters of this commonwealth during or after a storm
event.
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 of
once every 25 years; or stated in another way, the probability of
a twenty-five-year storm occurring in any one given year is 0.04 (i.e.,
a four-percent chance).
A vegetated area bordering perennial and intermittent streams
and wetlands that serves as a protective filter to help protect streams/wetlands
from the impacts of adjacent land uses.
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 right-of-way,
such as grading and repairing existing unpaved road surfaces, cutting
road banks, cleaning or clearing drainage ditches, and other similar
activities. Road maintenance activities that do not disturb the subbase
of a paved road (such as milling and overlays) are not considered
earth disturbance activities.
Temporary ponding and gradual release of stormwater falling
directly onto flat roof surfaces by incorporating controlled-flow
roof drains into building designs.
Any part of precipitation that flows over the land surface.
The volume of runoff that is captured (retained) and not
released into surface waters of the commonwealth during or after a
storm event.
Soils or other materials transported by surface water as
a product of erosion.
A barrier, dam, retention or detention basin located and
designed to retain rock, sand, gravel, silt, or other material transported
by stormwater runoff.
The placement, discharge, or any other introduction of sediment
into waters of the commonwealth occurring from the failure to properly
design, construct, implement or maintain control measures and control
facilities in accordance with the requirements of this Part.
The process by which mineral or organic matter is accumulated
or deposited by the movement of water.
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 walk for pedestrians constructed to the standards set forth
in this Part.
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).
Those portions of the contract documents consisting of written
technical descriptions of materials, equipment, construction systems,
standards and workmanship as applied to the work.
A depression in the embankment of a pond or basin, or other
overflow structure, that is used to pass peak discharges greater than
the maximum design storm controlled by the pond or basin.
The regulatory requirements to protect, maintain, reclaim,
and restore water quality under Title 25 of that Pa. Code and the
Clean Streams Law.
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. See also "return
period."
A system of pipes and/or open channels that convey intercepted
runoff and stormwater from other sources, but excludes domestic sewage
and industrial wastes.
Runoff from the surface of the land resulting from precipitation,
snow, or ice melt.
A land use or activity that generates higher concentrations
of hydrocarbons, trace metals, or toxicants than are found in typical
stormwater runoff.
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 facilities.
The Butler County Stormwater Management Plan for managing
stormwater runoff in Butler County as required by the Act of October
4, 1978, P.L. 864 (Act 167) and known as the "Storm Water Management
Act."
The plan prepared by the developer or his representative
indicating how stormwater runoff will be managed at the development
site in accordance with this Part. "Stormwater management site plan"
will be designated as "SWM site plan" throughout this Part.
[Amended by Ord. No. 2022-506, 1/27/2022]
A bridge, culvert, or other structure in excess of 100 feet
in length upstream to downstream which encloses regulated waters of
the commonwealth.
An avenue, boulevard, road, highway, freeway, parkway, lane,
viaduct and any other ways used by vehicular traffic, but not including
driveways, parking areas or walkways. "Street" includes the entire
right-of-way.
Excavation of 18 inches or more performed within public rights-of-way
or easements within the Township.
The smallest drainage unit of a watershed for which stormwater
management criteria has been established in the stormwater management
plan.
As defined in the Pennsylvania Municipalities Planning Code,
Act of July 31, 1968, P.L. 805, No. 247.[3]
[Amended by Ord. No. 2022-506, 1/27/2022]
The Board of Supervisors of the Township.
A low-lying stretch of land that gathers or carries surface
water runoff.
A roadway that is constructed for a defined amount of time
to facilitate a construction activity.
The Township of Cranberry, Butler County, Pennsylvania.
See "forest management."
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.
Detention storage located in underground tanks or vaults
designed to provide water quantity control through detention of stormwater
runoff.
The United States Department of Agriculture.
A public service including but not limited to electric service,
gas service, and cable TV service.
A walk for pedestrians constructed to the standards set forth
in the Public Improvements Code.
Includes all existing and proposed rivers, streams, creeks,
runs, rivulets, channels, ditches, drains and drainage facilities
which may flow continuously or flow intermittently during periods
of wet weather or rain.
Rivers, streams, creeks, rivulets, impoundments, ditches,
watercourses, storm sewers, lakes, dammed water, wetlands, ponds,
springs and 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 of Pennsylvania.
Area drained by a river, watercourse, or other surface water,
whether natural or artificial.
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 and similar areas. (The term includes but is
not limited to wetland areas listed in the State Water Plan, the United
States Forest Service Wetlands Inventory of Pennsylvania and a wetland
area designated by a river basin commission. This definition is used
by the United States Environmental Protection Agency and the United
States Army Corps of Engineers.)
A basin that has a permanent pool of water throughout the
year. A wet pond also may be called a "wet basin" or "retention pond."
[Ord. 2011-415, 5/5/2011, § 3]
1.
Storm Sewer Pipe. A minimum fifteen-inch diameter pipe shall be installed
for all storm sewers to be maintained by the Township. The following
are acceptable pipes for use in the Township. All pipe shall meet
appropriate AASHTO and ASTM standards.
[Amended by Ord. 2014-440, 1/30/2014]
2.
Storm Inlets. Storm inlets in street paving shall conform to the
construction standard in SS-05, Type "M" Inlet Detail, when used with
asphalt wedge curbs. Storm inlets in private developments that utilize
concrete curbing and Type "C" inlet tops may utilize the construction
standard in SS-06, Type "C" Inlet Detail. Storm inlets along streets
that will be dedicated for public use shall conform to the construction
standard in SS-06a, Concrete Curb Inlet Construction, when used with
concrete curbs. Type "C" inlets shall not be used on streets dedicated
for public use. Inlets shall be placed at all low points, at street
intersections and at points along both sides of the street to ensure
adequate drainage, but in no case shall the distance between inlets
along the street exceed 300 feet unless approved by the Engineer.
Inlets shall be installed at street intersections and shall be placed
on the tangent and not on the curved portion. Additional inlets shall
be constructed in areas as may be directed by the Engineer during
construction to provide for proper control of surface water.
[Amended by Ord. 2014-440, 1/30/2014]
A.
Inlet Grates.
(1)
All grates on slopes less than 12% shall be bicycle-safe and constructed
of steel and conform to the construction standards of SS-05B.
(2)
All grates situated on roadways with a long grade steeper than 12%
shall be constructed with a vane grate and shall conform to the construction
standards of SS-05C.
B.
Top Units (SS-05A). All tops shall be steel type M, unless otherwise
approved by the Engineer. Units shall be constructed and conform to
the construction standard in SS-05A.
C.
Ladder bars shall be installed in all inlets exceeding a depth of
five feet, and shall be in accordance with PennDOT Publication No.
72, Drawing RC-34. A poured concrete invert shall be formed in the
base of all inlets to provide full drainage of the structure.
D.
Inlets shall be specified as Type I-3 to meet maximum pipe outside
diameters (O.D.) as set forth in PennDOT Publication 702, Drawing
RC-34.
E.
Type M Inlet Connections (SS-15). Any connection to an existing storm
inlet shall be constructed and conform to the construction standard
in SS-15. Any connection to an existing inlet must be approved by
the Township in advance.
F.
For inlets containing a change in pipe size, the elevation for the
crown of the pipes shall be the same or the smaller pipe's crown shall
be at a higher elevation.
G.
All inlets shall provide a minimum two-inch drop between the lowest
inlet pipe invert elevation and the outlet pipe invert elevation.
H.
On curbed sections, a double inlet shall be placed at the low point
of sag vertical curves, or an inlet shall be placed on each side of
the low point at a distance not to exceed 100 feet, or at an elevation
not to exceed 0.2 foot above the low point.
I.
At all roadway low points, swales and easements shall be provided
behind the curb or swale and through adjacent properties to channelize
and direct any overflow of stormwater runoff away from dwellings and
structures.
J.
Inlets must be sized to accept the specified pipe sizes without knocking
out any of the inlet corners. All pipes entering or exiting inlets
shall be cut flush with the inside wall of the inlet. A note to this
effect shall be added to the SWM site plan or inlet details therein.
K.
Inlets shall have weep holes covered with geotextile fabric placed
at appropriate elevations to completely drain the subgrade prior to
placing the base and surface course on roadways.
L.
Inlets shall not have a sump condition in the bottom (unless designed
as a water quality BMP or specifically approved by the Township).
Pipe shall be flush with the bottom of the box or concrete channels
shall be poured.
M.
Inlets shall not be leveled with bricks or wooden shims. Prior to
final paving, a poured in-place riser shall be constructed in accordance
with Detail SS-25, Poured Concrete Riser.
3.
Storm Manholes. All manholes shall be precast concrete constructed
in accordance with the construction standards in SS-08, Typical Storm
Sewer Manhole, and Figure SS-07, Standard Manhole Frame and Cover.
Manholes shall be installed at all changes in alignment and grades
of storm sewers as may be directed by the Engineer to provide for
proper maintenance. If maintenance is not a problem, pipe may be installed
on a curve, provided that the deflection angle of the pipe joint does
not exceed the manufacturer's specifications. See SS-09 for pipes
under 48 inches in diameter and SS-10 for pipes over 48 inches in
diameter. Inlets may be substituted for manholes where practical.
4.
Maximum Distance Between Structures. The maximum distance between
structures (inlets or manholes) shall be 300 feet unless otherwise
approved by the Engineer.
A.
Yard Drains (rev. 2/01) SS-11. Yard drains shall be precast concrete
constructed in accordance with the construction standards in SS-11.
The top unit may be substituted with Type M tops, if approved by the
Engineer.
B.
Special Underdrains (rev. 1101) (SS-12). Underdrains shall be installed
in accordance with the standard in SS-12. The underdrain type shall
be directed by the Engineer.
5.
Inlet Connections (SS-03). All connections to Type C inlets shall
be in accordance with SS-03.
6.
Storm Sewer Lateral Connection. All sewer lateral connections shall
be in accordance with applicable law. All sewer lateral connections
shall be located at manholes, catch basins, or at locations approved
by the Township Engineer or his designated representative.
A.
All storm sewer laterals or runs designed to collect and/or connect
to individual residential lot roof drains shall be smooth-lined HDPE
(high-density polyethylene pipe).
B.
All storm sewer laterals or runs designed to collect and/or connect
to commercial structure roof drains shall be smooth-lined HDPE (high-density
polyethylene pipe).
[Added by Ord. No. 2022-506, 1/27/2022]
C.
Sump pumps shall discharge to infiltration or vegetative BMPs wherever
feasible.
[Added by Ord. No. 2022-506, 1/27/2022]
D.
SDR 35 pipe shall not be used on storm sewer conveyance systems.
[Added by Ord. No. 2022-506, 1/27/2022]
7.
Township Design Requirements for Stormwater Management.
A.
General Requirements.
(1)
The design criteria are intended to elaborate on Township ordinances such as Part 5, Required Improvements, and Part 6, Design Standards, of the Subdivision and Land Development Ordinance [Chapter 22] and to complement the Storm Water Management Act, P.L. 864, No. 167, 32 P.S. § 680.1 et seq. Said Act requires that actions be taken:
(a)
To assure that the maximum rate of stormwater runoff is no greater
after development than prior to development activities.
(b)
To manage the quantity, velocity and direction of resulting
stormwater runoff in a manner which otherwise adequately protects
health and property from possible injury.
(c)
To comply with federal and state regulations to implement a
program of stormwater controls. The Township is required to obtain
a federal permit for stormwater discharges from its separate storm
sewer systems under the National Pollutant Discharge Elimination System
(NPDES).
(d)
To utilize and preserve the desirable existing natural drainage
systems and to preserve the flood-carrying capacity of streams; to
maintain existing flows and quality of streams and watercourses.
(e)
To encourage natural infiltration of rainfall to preserve groundwater
supplies and streamflows.
1)
Minimization of impervious surfaces and infiltration of runoff
through seepage beds, infiltration trenches, etc., are encouraged,
where soil conditions and geology permit, to reduce the size or eliminate
the need for detention facilities.
2)
Infiltration BMPs should be dispersed throughout the site, made
as shallow as practicable, and located to maximize use of natural
on-site infiltration features while still meeting the other requirements
of this Part.
(f)
To implement an illegal discharge detection and elimination
program to address non-stormwater discharges into the Township's separate
storm sewer system.
(2)
Stormwater management design and construction will conform in
general to the applicable recognized national and state acts, manuals,
and references such as the Pennsylvania Storm Water Management Act,
32 P.S. § 680.1 et seq., and PennDOT published forms.
(3)
The SWM site plan approved by the Township shall be on site
throughout the duration of the regulated activities.
(4)
Applicants are encouraged to use low-impact development practices
to reduce the costs of complying with the requirements of this Part
and the State Water Quality Requirements.
(5)
When stormwater management facilities are proposed within 1,000
feet of a downstream township, the developer shall notify the downstream
township and provide a copy of the SWM plan, if requested, for review
and comment.
(6)
A copy of the approved erosion and sediment control plan and
any other permit, as required by PADEP or the Butler County Conservation
District, shall be available at the project site at all times if required
under Chapter 102.
(7)
All stormwater management plans shall be designed and certified
by individuals registered in the Commonwealth of Pennsylvania and
qualified to perform such duties.
(8)
Where applicable, stormwater management facilities shall comply
with the requirements of 25 Pa. Code, Chapter 105, Dam Safety and
Waterway Management, and § 404 of the Clean Water Act as
authorized by the United States Corps of Engineers. All regulated
earth disturbance activities are subject to permit requirements by
DEP under regulations at 25 Pa. Code, Chapter 102. When there is a
question whether wetlands may be involved, it is the responsibility
of the applicant or his agent to show that the land in question cannot
be classified as wetlands; otherwise, approval to work in the area
must be obtained from PADEP. The applicant shall meet requirements
as contained in 25 Pa. Code, Chapters 92 and 102, as required and
applicable as follows:
(9)
Stormwater management facilities that may impact a state highway
shall be subject to the approval of the Pennsylvania Department of
Transportation.
(10)
Stormwater runoff from a project site shall flow directly into
a natural watercourse or into an existing storm sewer system or onto
adjacent properties in a manner similar to the runoff characteristics
of the predevelopment flow. All natural streams, channels, swales,
drainage systems and/or areas of surface water connection shall be
maintained in their existing condition unless an alteration is approved
by the Township. All encroachment activities shall comply with the
requirements of 25 Pa. Code, Chapter 105, Dam Safety and Waterway
Management.
(a)
If diffused flow is proposed to be concentrated and discharged
onto adjacent property, the applicant must document that adequate
downstream conveyance facilities exist to safely transport the concentrated
discharge, or otherwise prove that no erosion, sedimentation, flooding,
or other harm will result from the concentrated discharge.
(11)
Stormwater runoff shall not be transferred from one watershed to
another unless the watersheds are subareas of a larger watershed that
are tributary to a common point of interest within or near the perimeter
of the property. Transfer of runoff from one watershed to another
under any other circumstances shall only be approved at the discretion
of the Township. Documentation shall be provided that peak flow rates
are not increased following development and there will be no detrimental
impact in downstream areas.
(12)
All stormwater runoff flowing over the project site shall be considered
in the design of the stormwater management facilities.
(13)
For any stormwater management facility requiring a permit to be issued
by PADEP, said permit along with supporting report and plans used
to secure the permit shall also be submitted.
(14)
The municipality may, after consultation with DEP, approve measures
for meeting the state water quality requirements other than those
in this Part, provided that they meet the minimum requirements of,
and do not conflict with, state law, including, but not limited to,
the Clean Streams Law.[1]
[Added by Ord. No. 2022-506, 1/27/2022]
[1]
Editor's Note: See 35 P.S. § 691.1 et seq.
B.
Stormwater Management Standards.
[Amended by Ord. 2014-440, 1/30/2014]
(1)
Design Storms. Stormwater management facilities on all development
sites shall control the peak stormwater discharge for the one- , two-
, ten- , twenty-five- , fifty- , and one-hundred-year design storms.
SCS twenty-four-hour, Type II rainfall distribution shall be used
in conjunction with rainfall depths from NOAA Atlas 14 for analyzing
stormwater runoff in pre- and post-development conditions, as well
as for designing runoff control facilities, except as noted in §
17-350.7B(2)(b). The rainfall data to be used for SCS TR-55 computations
in Cranberry Township are:
|
Design Storm Return Period
|
24-Hour Rainfall Depth
(inches)
|
|---|---|
|
1-year
|
2.02
|
|
2-year
|
2.41
|
|
10-year
|
3.38
|
|
25-year
|
4.00
|
|
50-year
|
4.50
|
|
100-year
|
5.03
|
|
All calculations shall be consistent with guidelines set forth
in the BMP Manual. The Pennsylvania Department of Transportation Drainage
Manual, Intensity-Duration-Frequency Curves, Publication 584, Chapter
7A, latest edition, shall be used in conjunction with the appropriate
time of concentration and return period to determine the rainfall
intensity in inches per hour. (For additional information or data
on other return periods, consult the Rainfall Duration Frequency Tables
for Pennsylvania, produced by PADEP, Office of Resource Management,
Bureau of Dams and Waterways Management, Division of Stormwater Management,
Harrisburg, February 1983, or in its most recent update.)
|
(2)
Calculation Methods.
(a)
Development Sites. For the purposes of computing peak flow rates,
runoff hydrographs, and storage requirements for development sites,
either the NRCS Rainfall-Runoff Method as presented in the most recent
version of Technical Release 55 (TR-55) shall be used, or the Rational
Method as specified in § 17-350.7B(1). When the Rational Method
is used, the technical data in Appendix 17-A[2] shall be used to determine rainfall intensities, time
of concentration, and runoff coefficients. The use of alternative
hydrologic methodologies may be approved by the Township if sufficient
justification and documentation of their application is provided.
1)
The Rational Method shall not be used to calculate runoff volume.
1.1)
Rational Method. This method may be
used for design of conveyance facilities only. Extreme caution should
be used by the design professional if the watershed has more than
one main drainage channel, if the watershed is divided so that hydrologic
properties are significantly different in one portion versus the other,
if the time of concentration exceeds 60 minutes or if stormwater runoff
volume is an important factor. The combination of Rational Method
hydrographs based on timing shall be prohibited.
2)
NRCS Rainfall-Runoff Method. This method shall be used to estimate
the change in volume due to regulated activities. Combining curve
numbers for land areas proposed for development with curve numbers
for areas unaffected by the proposed development into a single weighted
curve number is not acceptable.
3)
NRCS Rainfall-Runoff Method. This method is recommended for
design of stormwater management facilities and where stormwater runoff
volume must be taken into consideration. The following provides guidance
on the model applicability:
a)
NRCS's TR-55: limited to 100 acres in size.
b)
NRCS's TR-20, WinTR-20, WinTR-55, HEC-HMS: no watershed
size limitations.
c)
The NRCS antecedent runoff condition II (ARC II,
previously AMC II) must be used for all simulations. The use of continuous
simulation models that vary the ARC are not permitted for stormwater
management purposes.
d)
For comparison of peak flow rates, flows shall be
rounded to a tenth of a cubic foot per second (cfs).
4)
The time of concentration is to represent the average condition
that best reflects the hydrologic response of the area. The following
time of concentration (Tc) computational methodologies shall be used
unless another method is preapproved by the Township Engineer:
a)
Predevelopment — NRCS's Lag Equation:
|
Time of Concentration = Tc = [(Tlag/.6) * 60] (minutes)
| |||
 | |||
|
Where
| |||
|
Tlag = Lag time (hours).
| |||
|
L = Hydraulic length of watershed (feet).
| |||
|
Y = Average overland slope of watershed (percent).
| |||
|
S = Maximum retention in watershed as defined by: S = [(1,000/CN) —
10].
| |||
|
CN = NRCS curve number for watershed.
| |||
b)
Post-development; commercial, industrial, or other
areas with large impervious areas (greater than 20% impervious area):
NRCS Segmental Method. The length of sheet flow shall be limited to
100 feet. Tc for channel and pipe flow shall be computed using Manning's
equation.
c)
Post-development; residential, cluster, or other
low-impact designs less than or equal to 20% impervious area: NRCS
Lag Equation or NRCS Segmental Method.
5)
Additionally, the following provisions shall apply to calculations
for time of concentration:
a)
The post-development Tc shall never be greater than
the predevelopment Tc for any watershed or subwatershed. This includes
when the designer has specifically used swales to reduce flow velocities.
In the event that the designer believes that the post-development
Tc is greater, it will still be set by default equal to the predevelopment
Tc for modeling purposes.
b)
The minimum Tc for any watershed shall be five minutes.
c)
The designer may choose to assume a five-minute
Tc for any post-development watershed or subwatershed without providing
any computations.
d)
The designer must provide computations for all predevelopment
Tc paths. A five-minute Tc cannot be assumed for predevelopment.
e)
Undetained fringe areas (areas that are not tributary
to a stormwater facility but where a reasonable effort has been made
to convey runoff from all new impervious coverage to best management
practices) may be assumed to represent the predevelopment conditions
for purpose of Tc calculation.
6)
In addition to § 17-350.7.B(2)(a) and (b), stormwater
runoff volume controls shall be implemented using the Design Storm
Method or the Simplified Method as defined below. For regulated activity
areas equal to or less than one acre that do not require hydrologic
routing to design the stormwater facilities, this Part establishes
no preference for either method; therefore, the applicant may select
either method on the basis of economic considerations, the intrinsic
limitations on applicability of the analytical procedures associated
with each methodology, and other factors.
a)
The Design Storm Method (CG-1 in the BMP Manual)
is applicable to any sized regulated activity. This method requires
detailed modeling based on site conditions.
i.
Do not increase the post-development total runoff
volume when compared to the predevelopment total runoff volume for
the two-year/twenty-four-hour storm event.
ii.
For hydrologic modeling purposes:
|
[A]
|
Existing nonforested pervious areas must be considered meadow
(good condition) for predevelopment hydrologic calculations.
|
|
[B]
|
Twenty percent of existing impervious area, when present within
the proposed project site, shall be considered meadow (good condition)
for predevelopment hydrologic calculations for redevelopment.
|
b)
The Simplified Method (CG-2 in the BMP Manual) is
independent of site conditions and should be used if the Design Storm
Method is not followed. This method is not applicable to regulated
activities greater than one acre or for projects that require detailed
design of stormwater storage facilities. For new impervious surfaces:
i.
Stormwater facilities shall capture at least the
first two inches of runoff from all new impervious surfaces.
ii.
At least the first one inch of runoff from new
impervious surfaces shall be permanently removed from the runoff flow,
i.e., it shall not be released into surface waters of the commonwealth.
Removal options include reuse, evaporation, transpiration, and infiltration.
iii.
Wherever possible, infiltration facilities should
be designed to accommodate infiltration of the entire permanently
removed runoff; however, in all cases at least the first 0.5 inch
of the permanently removed runoff should be infiltrated.
iv.
Actual field infiltration tests at the location
of the proposed elevation of the stormwater BMPs are required. Infiltration
tests shall be conducted in accordance with the BMP Manual. Notification
of the Township shall be provided to allow witnessing of the testing.
c)
In cases where it is not possible or desirable to use infiltration-based best management practices to partially fulfill the requirements in either § 17-350, Subsection 7B(2)(a)6)a) or b), the following procedure shall be used:
i.
At a minimum, the following documentation shall
be provided to justify the decision to not use infiltration BMPs:
|
[A]
|
Description of and justification for field infiltration/permeability
testing with respect to the type of test and test locations.
|
|
[B]
|
An interpretive narrative describing existing site soils and
their structure as these relate to the interaction between soils and
water occurring on the site. In addition to providing soil and soil
profile descriptions, this narrative shall identify depth to seasonal
high water tables and depth to bedrock, and provide a description
of all subsurface elements (fragipans and other restrictive layers,
geology, etc.) that influence the direction and rate of subsurface
water movement.
|
|
[C]
|
A qualitative assessment of the site's contribution to annual
aquifer recharge shall be made, along with identification of any restrictions
or limitations associated with the use of engineered infiltration
facilities.
|
|
[D]
|
The provided documentation must be signed and sealed by a professional
engineer or geologist.
|
ii.
The following water quality pollutant load reductions
will be required for all disturbed areas within the proposed development:
|
Pollutant Load
|
Units
|
Required reduction
|
|---|---|---|
|
Total suspended solids (TSS)
|
Pounds
|
85%
|
|
Total phosphorous (TP)
|
Pounds
|
85%
|
|
Total nitrate (NO3)
|
Pounds
|
50%
|
iii.
The performance criteria for water quality best
management practices shall be determined from the Pennsylvania Stormwater
Best Management Practices Manual, most current version.
7)
The applicable worksheets from the BMP Manual must be used in
calculations to establish volume control.
[2]
Editor's Note: Appendix 17-A is included as an attachment to this chapter.
(b)
Stormwater Collection/Conveyance Facilities. For the purpose of designing
storm sewers, open swales and other stormwater runoff collection and
conveyance facilities, the Rational Method shall be utilized employing
the technical data referenced in § 17-350.7B(2)(a). The
design storm for storm sewers and swales that will discharge to detention
facilities is the one-hundred-year storm. The ten-year design storm
for storm systems discharging to detention facilities shall be acceptable,
provided that it can be documented that runoff exceeding the ten-year
capacity of the storm system during a one-hundred-year storm event
will ultimately discharge to the detention facility by alternative
means, without endangering public safety or damaging private property.
The design storm for all other on-site storm sewers or swales is the
ten-year storm event, provided that larger storm events will not impact
private property.
1)
All stormwater collection and/or conveyance systems routing
water through or around the development site shall be designed for
the one-hundred-year storm event, unless it can be documented that
said facilities will not create a hazard.
2)
A drainage easement shall be provided to contain and convey
the one-hundred-year flood event throughout the project site, beginning
at the furthest upstream property line of the proposed development
in the watershed. Where watercourses traverse a development site,
drainage easements (with a minimum width of 20 feet and including
the one-hundred-year water surface) shall be provided conforming to
the line of such watercourses. The terms of the easement shall prohibit
excavation, the placing of fill or structures, and any alterations
that may adversely affect the flow of stormwater within any portion
of the easement. Also, maintenance, including mowing of vegetation
within the easement, may be required, except as approved by the appropriate
governing authority.
3)
The Rational Method may be used for design of conveyance facilities
only. Extreme caution should be used by the design professional if
the watershed has more than one main drainage channel, if the watershed
is divided so that hydrologic properties are significantly different
in one versus the other, if the time of concentration exceeds 60 minutes,
or if stormwater runoff volume is an important factor. The combination
of Rational Method hydrographs based on timing shall be prohibited.
4)
All structures (culverts or bridges) proposed to convey runoff
under a Township road shall be designed to pass the fifty-year design
storm with a minimum one foot of freeboard measured below the lowest
point along the top of the roadway.
(c)
Stormwater Management Facilities. Peak runoff rates for all on-site
areas and off-site areas impacting the project site shall be determined
and considered in the design of stormwater management facilities.
These calculations shall be based on land use, time of concentration
and other standard hydrologic parameters as noted in § 17-350.7B(2)(a).
(d)
All calculations shall be consistent with the guidelines set forth
in the BMP Manual, as amended herein.
(e)
Impervious Areas:
(3)
Cranberry Township HEC-1 Watershed Model. All proposed subdivision
and land developments employing stormwater management facilities designed
to control five acres or more of watershed area, or less at the Township's
discretion, shall be analyzed by the Township with the Cranberry Township
HEC-1 Watershed Model. The resulting impacts in downstream areas associated
with the watershed modeling shall be the determining factor for approval
of proposed stormwater management plans.
(4)
Performance Standards.
(a)
Where, in the judgment of the Township, the additional volume
or peak flow of stormwater runoff associated with a proposed development
site will have a detrimental impact on downstream properties or drainage
structures and/or on existing documented downstream flooding concerns,
post-development peak flows may be required to be reduced to less
than otherwise determined site allowable release rates [§ 17-350.7B(4)(e)].
Under these circumstances, acceptable peak flow rates will be determined
at the discretion of the Township for a given storm event(s) based
on existing downstream restrictions. Additional hydrologic studies
or analyses may also be required. Alternative mitigation measures
in lieu of increased peak flow reduction may be considered by the
Township on a case-by-case basis.
(b)
Release Rate Percentage (RR%).
1)
The release rate percentage defines the percentage of the predevelopment
peak rate of runoff that can be discharged from the site following
development as determined in the Cranberry Township Stormwater Management
Plan. As per the plan, the Township shall be divided into three separate
watersheds as noted below.
2)
These watersheds are further subdivided into subwatersheds of
similar hydrologic characteristics upon which release rate percentages
for each subwatershed are determined. All subdivisions and land developments
located in these subwatersheds that result in an increase in site
runoff following development shall use the release rate percentages
designated on the Release Rate Percentage Map in Appendix 17-C[3] as a guideline to determine allowable release rates [§ 17-350.7.B(4)(e)]
for the development site.
[3]
Editor's Note: Appendix 17-C is included at the end of this chapter.
3)
In accordance with the Southwest Lower Connoquessing Stormwater
Planning Study prepared by Herbert, Rowland & Grubic, Inc., dated
March 10, 2021, release rates for subwatersheds located within Wolfe
Run and Kaufman Run watershed shall not exceed 90%. Resolution No.
2021-18, Item 2, supports the recommendation to update the release
rates in the Township Stormwater Management Ordinance.
[Added by Ord. No. 2022-506, 1/27/2022]
(c)
The following sites may be exempted from the designated release
rate percentage upon approval by the Township.
1)
Development sites comprising three acres or less located in
a subwatershed with a designated release rate percentage of less than
100% shall employ a release rate of 100% to determine the site's allowable
release rate, provided that conditions cited in § 17-350.7B(4)(a),
are not evident in downstream areas.
2)
Development sites where application of the designated release
rate percentage may induce significant economic or site layout constraints
may request a modification of the designated release rate percentage.
Under these circumstances, the developer shall submit a proposed stormwater
management plan with sufficient detail for the Township to evaluate
the impact of the development with the Township HEC-1 Watershed Model
[§ 17-350.7B(3)]. The Township shall approve or disapprove
the proposed plan based on the resulting impacts in downstream areas
indicated by the watershed model. Based on the watershed analysis,
the following procedures shall be followed at the discretion of the
Township.
a)
The developer shall submit a revised stormwater
management plan reducing peak flow rates to a level acceptable to
the Township on the basis of the evaluation with the Township HEC-1
Watershed Model. With the exception of provisions noted in § 17-350.7B(4)(a),
the maximum reduction that may be imposed on a site is the designated
release rate percentage as per the Release Rate Percentage Map (Appendix
17-C).[4]
[4]
Editor's Note: Appendix 17-C is included at the end of this chapter.
b)
The Township may approve the developer's plan, provided
that the Township HEC-1 Watershed Model shows minimal impact at any
point downstream that may result from runoff associated with the proposed
development site. This approval shall be evaluated by the Township
on the basis of numerous factors, including watershed location, erosional
concerns and provisions cited in § 17-350.7B(4)(a).
(d)
Predevelopment Conditions. The cover type(s) for all sites shall
be consistent with site conditions based on aerial photography of
the Township dated May 27, 1999, and employed in the watershed models
developed for the Cranberry Township Stormwater Management Plan. These
cover types shall be field verified, and the runoff curve numbers
(RCN) presented in Table 1 shall be used to determine predevelopment
peak flow rates when employing the SCS TR-55 Soil Complex Methodology.
1)
For the purposes of predevelopment peak flow rate and volume
determination, existing nonforested pervious areas conditions shall
be considered as meadow (good condition).
2)
For the purposes of predevelopment peak flow rate and volume
determination, 20% of existing impervious area, when present, shall
be considered meadow (good condition).
|
Table 1
| |||
|---|---|---|---|
|
SCS Runoff Curve Number (RCN)
| |||
|
Cover Type
|
Hydrologic Soil Group
| ||
|
B
|
C
|
D
| |
|
Woods
|
55
|
70
|
77
|
|
Meadow (good condition)
|
58
|
71
|
78
|
3)
The runoff coefficients (c) to be employed with the Rational
Formula for these cover types shall be consistent with the table provided
in Appendix 17-A.[5]All hydrologic parameters used to calculate peak flow rates
shall use the appropriate coefficients pertaining to these conditions
as noted in § 17-350.7B(2)(a).
[5]
Editor's Note: Appendix 17-A is included as an attachment to this chapter.
(e)
Allowable Release Rates. The allowable release rates from stormwater
management facilities, or a development site in general, shall be
less than or equal to the predevelopment peak runoff rates generated
for the site. All stormwater runoff discharged from the site that
is not controlled by a stormwater management facility shall be accounted
for in the determination of the allowable release rates for the full
range of storm events. The allowable release rate (RR) for a site
as per § 17-350.7B(4)(b), shall be determined by the following
equation for each design storm event:
|
Predevelopment Peak Flow Rate x RR%/100 = Allowable RR
|
(f)
Post-Development Conditions. The hydrologic parameters used
to develop peak flow rates shall be reflective of anticipated soil
runoff characteristics following grading operations of the site, with
areas disturbed by heavy machinery associated with topsoil stripping,
excavation and engineered fill modeled as meadow (good condition)
with Hydrologic Soil Group D characteristics as per Table 1 of §
17-350.7B(4)(d).
(g)
Redevelopment Sites. Existing sites proposed for redevelopment
that currently provide no stormwater management, and/or sites that
will remove existing or inadequate stormwater management facilities,
shall provide stormwater management as per § 17-350.7B. For the
purposes of determining predevelopment peak flow rates, the developed
site shall be considered as meadow (good condition) with Hydrologic
Soil Group D characteristics as per Table 1 of § 17-350.7B(4)(d),
or a weighted runoff coefficient of existing cover types should that
yield lower coefficient values.
(h)
SWM site plans shall show the locations of existing and proposed
on-lot wastewater facilities and water supply wells.
[Added by Ord. No. 2022-506, 1/27/2022]
(5)
The low-impact development practices provided in the BMP Manual, as may be amended from time to time, said amendments incorporated herein by reference, and in the Operation and Maintenance Agreement, in form and substance approved by the Township Solicitor and the Board of Supervisors, of Chapter 17 shall be utilized for all regulated activities to the maximum extent practicable.
(6)
Drainage areas tributary to sinkholes or closed depressions
in areas underlain by limestone or carbonate geologic features shall
be excluded from the modeled point of analysis defining predevelopment
flows. If left undisturbed during construction activities, areas draining
to closed depressions may also be used to reduce peak runoff rates
in the post-development analysis. New, additional contributing runoff
should not be directed to existing sinkholes or closed depressions.
(7)
Where uniform flow is anticipated, the Manning's equation shall be
used for hydraulic computations and to determine the capacity of open
channels, pipes, and storm sewers. The Manning's equation should not
be used for analysis of pipes under pressure flow or for analysis
of culverts. Manning's "n" values shall be obtained from PennDOT's
Drainage Manual, Publication 584. Inlet control shall be checked at
all inlet boxes to ensure the headwater depth during the ten-year
design event is contained below the top of grate for each inlet box.
(8)
The Township has the authority to require that computed existing
runoff rates be reconciled with field observations, conditions and
site history. If the designer can substantiate, through actual physical
calibration, that more appropriate runoff and time of concentration
values should be utilized at a particular site, then appropriate variations
may be made upon review and recommendation of the Township.
C.
Stormwater Management Plan.
(1)
General Requirements.
(a)
No final subdivision or land development plan shall be approved,
no permit authorizing construction issued, or any earthmoving or land
disturbance activity initiated until the final stormwater management
plan for the development site is approved in accordance with the provisions
of this Part. The design of all stormwater management facilities shall
incorporate sound engineering principles and practices. The Township
shall reserve the right to disapprove any design that would result
in the continuation or exacerbation of a documented adverse hydrologic
or hydraulic condition within the watershed, as identified in the
plan.
(b)
A letter from the Butler County Conservation District approving
the erosion and sedimentation control plan must also be received prior
to the initiation of any grading. In the event that submission to
the Butler County Conservation District is not required by the Township,
an erosion and sediment pollution control plan prepared in accordance
with the most recent version of PADEP Chapter 102, Erosion and Sedimentation
Control Program Manual, must be approved by the Township.
(c)
Exemptions.
1)
The following activities are specifically exempt from this Part.
a)
Use of land for gardening primarily for home consumption.
b)
Use of land for construction of landscaping improvements,
provided that such improvements do not significantly alter the runoff
characteristics for the land.
c)
Agricultural use of lands when operated in accordance
with a farm conservation plan approved by the local soil conservation
district, or when it is determined by the local soil conservation
district that such use will not cause excessive erosion and sedimentation.
Agricultural activities are exempt from the rate control and SWM site
plan preparation requirements of this Part, provided that the activities
are performed according to the requirements of 25 Pa. Code Chapter
102.
3)
The applicant must demonstrate that the following BMPs are being
utilized to the maximum extent practicable to receive consideration
for the exemptions:
a)
Design around and limit disturbance of floodplains,
wetlands, natural slopes over 15%, existing native vegetation, and
other sensitive and special value features.
b)
Maintain riparian and forested buffers.
c)
Limit grading and maintain nonerosive flow conditions
in natural flow paths.
d)
Maintain existing tree canopies near impervious
areas.
e)
Minimize soil disturbance and reclaim disturbed
areas with topsoil and vegetation.
f)
Direct runoff to pervious areas.
4)
The applicant must demonstrate that the proposed development/additional
impervious area will not adversely impact the following:
5)
An applicant proposing regulated activities may be eligible
for exemption from rate control, volume control, or stormwater management
site plan requirements in this Part according to the following table:
|
Table 350.7C5
| |
|---|---|
|
Exemptions and Submission Requirements
| |
|
New Impervious Area1, 2
(square footage)
|
Applicant Must Provide
|
|
0 to less than 2,500
|
No submission is required
|
|
2,500 to less than 5,000
|
Documentation of new impervious surfaces3
|
|
5,000 and greater
|
Rate controls, volume controls and SWM site plan
|
|
NOTES:
| |
|---|---|
|
1
|
New impervious area since the date of adoption of this Part.
|
|
2
|
Gravel in existing condition shall be considered pervious and
gravel in proposed condition shall be considered impervious.
|
|
3
|
The small project stormwater management application in form
and substance approved by the Township Solicitor and the Board of
Supervisors shall be used to document new impervious surfaces.
|
6)
Single-family residential activities are exempt from these requirements,
provided that the construction:
a)
Complies with §§ 17-350.7C(1)(c)8),
17-350.7C(1)(c)2), 17-350.7C(1)(c)3), and 17-350.7C(1)(c)4); and
b)
Has building setback 75 feet from downstream property
lines; and
d)
The Township can require more information or require
mitigation of certain impacts through installation of stormwater management
BMPs if there is a threat to property, health, or safety.
7)
An applicant proposing regulated activities, after demonstrating
compliance with §§ 17-350.7C(1)(c)2), 17-350.7C(1)(c)3),
and 17-350.7C(1)(c)4) may be exempted from various requirements of
this Part if documentation can be provided that a downstream man-made
water body (i.e., reservoir, lake, or man-made wetlands) has been
designed or modified to address the potential stormwater flooding
impacts of the proposed development.
8)
The purpose this section is to ensure consistency of stormwater
management planning between local ordinances and NPDES permitting
(when required) and to ensure that the applicant has a single and
clear set of stormwater management standards to which the applicant
is subject. The Township may accept alternative stormwater management
controls under this section, provided that:
a)
The Township, in consultation with the PADEP (or
delegated authority), determines that meeting the volume control requirements
[See § 17-350.7B(2)(a)6).] is not possible or places an
undue hardship on the applicant.
b)
The alternative controls are documented to be acceptable
to PADEP (or delegated authority) for NPDES requirements pertaining
to post-construction stormwater management requirements.
c)
The alternative controls are in compliance with
all other sections of this Part, including but not limited to §§ 17-350.7A(1)(c),
17-350.7C(1)(c)8), 17-350.7C(1)(c)2), 17-350.7C(1)(c)3), and 17-350.7C(1)(c)4).
9)
Forest management and timber operations are exempt from the
rate and volume control requirement and SWM site plan preparation
requirement of this Part, provided that the activities are performed
according to the requirements of 25 Pa. Code Chapter 102. It should
be noted that temporary roadways are not exempt.
10)
The Township may deny or revoke any exemption pursuant
to this section at any time for any project that the Township believes
may pose a threat to public health, safety, property or the environment.
11)
Small Developments. A "small development" shall
be defined as a site that creates less than 5,000 square feet of impervious
surface, and shall be exempt from the preparation of a detailed stormwater
management plan as specified in § 17-350.7C. However, such
developments must still provide safe management of stormwater runoff
in accordance with the performance standards specified in § 17-350.7B
of this Part and as approved by the Township.
a)
Applications for small developments shall include
a plan that describes, narratively and graphically, the type and location
of proposed on-site stormwater management techniques or the proposed
connection to an existing storm sewer system.
b)
Runoff calculations, as required at the discretion
of the Township, shall be prepared in accordance with § 17-350.7B(6).
c)
The Township shall review and approve the proposed
provisions for stormwater management for a small development.
d)
Under the appropriate circumstances, the Township
may waive stormwater management requirements required per § 17-350.7B(1),
provided that it is documented that no detrimental impacts associated
with erosion or capacity of storm structures will occur in downstream
locations. Design provisions to effectively manage stormwater runoff
discharged from the site shall be required.
12)
Proposed impervious surfaces (structures, roads,
paved areas and buildings) shall include plans and profiles of roads
and paved areas and floor elevations of buildings.
[Added by Ord. 2014-440, 1/30/2014]
(2)
Stormwater Management Report. A written and bound report shall
be submitted, including, but not necessarily limited to, the following
information:
(a)
Proposed name or identifying title of project, the name and
address of the landowner and developer of the project site, as well
as the name, address, and phone number of the consultant who prepared
the stormwater management plan.
(b)
Stormwater management report date and date of the latest revision
to the report.
(c)
Typewritten narrative report that should include sections describing
the following items:
1)
Stormwater management plan objectives. Statement of the regulated
activity describing what is being proposed. Overall stormwater management
concept with description of permanent stormwater management techniques,
including construction specifications and materials to be used for
stormwater management facilities.
2)
Hydrologic procedures used to develop plan.
3)
Description(s) of predevelopment watershed conditions.
4)
Description(s) of post-development watershed conditions.
5)
Descriptions of proposed plan and methods to handle post-development
runoff.
6)
Description(s) of proposed detention facility(s) and proposed
outlet control.
7)
Summary tables for:
a)
Predevelopment Hydrologic Soil Group (HSG) assumptions,
curve numbers (CN), computation of average slope, hydraulic length,
computed time of concentration.
b)
Existing conditions runoff volume and peak rate
of runoff.
c)
Post-development runoff volume and peak rate of
runoff.
d)
Undetained areas; areas to ponds.
e)
Land use for each subarea.
f)
Hydrologic Soil Group (HSG) assumptions, curve numbers
(CN).
g)
Time of concentration computed for each subarea.
h)
Post-development peak rate of runoff routed to ponds
and out.
i)
Pond maximum return period design data, including:
maximum water surface elevation, berm elevation, and emergency spillway
elevation.
j)
Water quality depth and volume requirements.
8)
Soil names and boundaries with identification of the Hydraulic
Soil Group classification, including rock outcroppings.
9)
Expected project schedule.
10)
Location map showing the project site and its location
relative to release rate districts.
11)
Detailed description of the existing site conditions,
including a site evaluation completed for projects proposed in areas
of carbonate geology or karst topography and other environmentally
sensitive areas such as brownfields.
12)
Total site area pre- and post-, which must be equal
or have an explanation as to why it is not.
13)
Total site impervious area.
14)
Total off-site areas.
15)
Number and description of stormwater management
facilities.
16)
Whether the site is a water quality sensitive (WQS)
development.
17)
Whether the site is in a defined sensitive area.
18)
Types of water quality and recharge systems used,
if applicable.
19)
Other pertinent information, as required.
20)
Reports that do not clearly indicate the above
information may be rejected for review by the Township and will be
returned to the applicant.
21)
The effect of the project (in terms of runoff volumes,
water quality, and peak flows) on surrounding properties and aquatic
features and on any existing Township stormwater collection system
that may receive runoff from the project site.
22)
Description of the proposed changes to the land
surface and vegetative cover, including the type and amount of impervious
area to be added.
(d)
Watershed maps delineating predevelopment and post-development
watershed boundaries, as well as the flow path and segments used to
determine time of concentrations for each watershed. The Chapter 93
watershed and discharge waterway classification (CWF, TSF, etc.) must
also be included on the plan.
(e)
All hydrologic, hydraulic, and structural computations, calculations,
assumptions, and criteria associated with the stormwater management
plan, appended and referenced in the narrative.
1)
Details of the berm embankment and outlet structure indicating
the embankment top elevation, embankment side slopes, top width of
embankment, emergency spillway elevation, perforated riser dimensions,
pipe barrel dimensions and dimensions and spacing of antiseep collars.
2)
Design computations for the control structures (pipe barrel
and riser, etc).
3)
A plot or table of the stage-storage (volume vs. elevation)
and all supporting computations.
4)
Routing computations.
(f)
Storm sewer calculations and watershed map delineating all subareas
used to size and compute flows for the storm sewer system.
(g)
Operation and Maintenance Program. The report shall contain
a proposed maintenance plan for all stormwater control facilities,
in accordance with the following:
1)
Identify the proposed ownership entity (e.g., Township, property
owner, homeowners' association, other management entity) and maintenance
responsibility for all permanent stormwater management facilities.
2)
A maintenance program for all facilities that outlines the anticipated
maintenance tasks, required inspection, frequencies and inspection
guidelines. Provisions for scheduled vegetation maintenance for open
facilities shall be included to prevent overgrowth from limiting proper
operation and inspection of the facility(s).
3)
Include a maintenance program for all post-construction stormwater
BMPs, outlining the type of maintenance activities, probable frequencies,
personnel and equipment requirements, and estimated annual maintenance
costs. The maintenance program shall include specific requirements
for during construction and for after construction.
4)
Identify the method of financing for continuing operation and
maintenance of the facility.
5)
The owner is responsible for operation and maintenance of the
stormwater BMPs. If the owner fails to adhere to the operation and
maintenance (O&M) agreement, the Township may perform the services
required and charge the owner appropriate fees. Nonpayment of fees
may result in a lien against the property. A note shall be placed
on the recorded plan: "As per the approved stormwater management plan,
the Township shall have right of access to the on-site detention facility
for the right of maintenance, monitoring, and/or sampling, in the
event the owner, assigns or heirs do not adequately maintain or monitor
the facility. The owner, assigns or heirs shall reimburse the Township
for all costs associated with said maintenance. The aformentioned
rights granted the Township in no way diminish the responsibility
of the owner, assigns or heirs of said maintenance and monitoring,
and no liability will be assumed by the Township associated with required
access for maintenance or monitoring purposes."
6)
Identification of short-term and long-term ownership, operation,
and maintenance responsibilities as well as schedules and costs for
inspection and maintenance activities for each permanent stormwater
or drainage BMP, including provisions for permanent access or maintenance
easements.
7)
If a development consists of structures or lots that are to
be separately owned and in which streets, sewers, and other public
improvements are to be dedicated to the Township, stormwater control
facilities/BMPs may also be dedicated to and maintained by the Township.
The Township has full discretion to accept any such dedication.
8)
If a development site is to be maintained in a single ownership
or if sewers and other public improvements are to be privately owned
and maintained, then the ownership and maintenance of stormwater control
facilities/BMPs shall be the responsibility of the owner or private
management entity.
9)
Facilities, areas, or structures used as stormwater BMPs shall
be enumerated as permanent real estate appurtenances and recorded
as deed restrictions or easements that run with the land.
10)
The SWM site plan and report shall be recorded
as a restrictive deed covenant that runs with the land.
11)
The Township may take enforcement actions against
an applicant for failure to satisfy any provision of this Part.
12)
The Township, upon recommendation of the Township
Engineer, shall make the final determination on the continuing maintenance
responsibilities prior to final approval of the SWM site plan and
report. The Township may require a dedication of such facilities as
part of the requirements for approval of the SWM site plan. Such a
requirement is not an indication that the Township will accept the
facilities. The Township reserves the right to accept or reject the
ownership and operating responsibility for any portion of the stormwater
management controls.
13)
The Township's acceptance of any dedicated stormwater
BMP may be conditioned upon the payment of a fee to cover future costs
of inspection, operation, maintenance and replacement, said fee to
be calculated by the Township Engineer.
14)
It shall be unlawful to alter or remove any permanent
stormwater BMP required by an approved SWM site plan or to allow the
property to remain in a condition that does not conform to an approved
SWM site plan, unless the Township grants an exception in writing.
15)
Prior to final approval of the SWM site plan and
report, the applicant shall sign an operation and maintenance (O&M)
agreement in form and substance approved by the Township Solicitor
and the Board of Supervisors.
16)
No person shall modify, remove, fill, landscape,
or alter any existing stormwater BMP, facilities, areas, or structures,
unless it is part of an approved maintenance program, without the
written approval of the Township.
17)
No person shall place any structure, fill, landscaping,
or vegetation into a stormwater BMP, facilities, areas, structures,
or within a drainage easement which would limit or alter the functioning
of the BMP without the written approval of the Township.
18)
The owner, successor and assigns shall maintain
all facilities in accordance with the approved maintenance schedule
in the O&M agreement.
[Added by Ord. No. 2022-506, 1/27/2022]
19)
The owner shall convey to the municipality conservation easements
to assure access for periodic inspections by the municipality and
maintenance, as necessary.
[Added by Ord. No. 2022-506, 1/27/2022]
20)
The owner shall keep on file with the municipality the name, address
and telephone number of the person or company responsible for maintenance
activities; in the event of a change, new information shall be submitted
by the owner to the municipality within 10 working days of the change.
[Added by Ord. No. 2022-506, 1/27/2022]
(3)
A copy of the proposed erosion and sedimentation control narrative
and plans shall be submitted. The narrative and accompanying plans
shall also be submitted to the Butler County Conservation District
for review and approval.
(4)
Stormwater Controls. All proposed stormwater runoff control
measures must be shown on the development site plans, including methods
for collecting, conveying and storing stormwater runoff on-site. The
preliminary plan should provide information on the general type, location,
sizing, etc., of all proposed facilities and their relationship to
the existing watershed drainage system.
(a)
The development site plan shall show the present contours of
the land and the proposed contours of the land after completion of
the proposed grading at one-foot intervals where slopes are less than
5%, two-foot intervals where the average slope is between 5% and 15%
and at five-foot intervals where the average slope exceeds 15%.
(5)
Easements, Rights-of-Way, Deed Restrictions. All existing and
proposed easements and rights-of-way for drainage and/or access to
stormwater control facilities shall be shown, and the proposed owner
identified. Drainage easements shall be delineated and recorded for
all permanent facilities, swales and storm sewers to identify their
owner, purpose, permanency and provide maintenance access. Any areas
subject to special deed restrictions relative to or affecting stormwater
management on the development site shall be shown. Easements shall
prohibit excavation, the placement of fill, vegetation, or structures,
and any alteration that may adversely affect the flow of stormwater
or the function of a stormwater BMP in the easement.
(a)
Easements are required for all areas used for off-site stormwater
control.
(b)
Where possible, easements shall be centered on side and/or rear
lot lines.
(c)
Nothing shall be planted or placed within the easement that
would adversely affect the function of the easement or conflict with
any conditions associated with such easement.
(d)
All easements shown on the plan shall identify the owner, purpose
or use. Example: "Private drainage easement to homeowners' association
for ownership and maintenance."
(6)
Permits/Approvals. A list of any approvals/permits relative
to stormwater management that will be required from other governmental
agencies (e.g., dam or encroachment permits from PADEP) and anticipated
dates of submission/receipt should be included with the plan submission.
Copies of applications may be requested by the Township. All stormwater
or drainage-related computations or reports associated with these
permit applications shall be submitted to the Township for reference
and for review. Copies of all approved aforementioned permits and
conditions shall be submitted to the Township upon receipt for reference
purposes.
(7)
One-Hundred-Year Floodplain Delineation.
(a)
Stormwater management facilities located within or affecting the floodplain of any watercourse shall also be subject to the requirements of § 27-504, Floodplain Areas Overlay District, of the Zoning Ordinance [Chapter 27], as amended from time to time, which regulates construction and development within areas of the Township subject to flooding.
(b)
The one-hundred-year floodplain must be delineated on all plans
for all watercourses which have a watershed area of 150 acres or greater.
Where, in the judgment of the Township, private property or public
facilities may be adversely affected by the proposed activity, the
one-hundred-year floodplain shall be established for any watercourse.
(c)
The one-hundred-year floodplain shall be delineated by one of
the following methods:
1)
The Flood Insurance Study by the Federal Emergency Management
Agency (FEMA).
2)
A hydrologic report prepared by an individual registered in
the Commonwealth of Pennsylvania to perform such duties. Calculations
and channel hydraulic characteristics used to determine floodplain
limits shall be provided.
(d)
Minimum Basement Elevation. The minimum basement elevation of all structures adjacent to a stream, pond or stormwater management facility shall be a minimum of 1 1/2 feet above the one-hundred-year water surface elevation, measured at the upstream extent of the building. The regulating one-hundred-year water surface elevation associated with ponds or stormwater management facilities shall be the one-hundred-year elevation determined for emergency spillway calculations. All other provisions cited in § 27-504, Floodplains Areas Overlay District, of the Zoning Ordinance [Chapter 27] shall apply.
(8)
Post-Construction Stormwater Management BMP Controls. Show any
and all existing and proposed stormwater management or drainage controls
and/or structures, such as storm sewers, swales, culverts, etc., that
are located on the development site, or that are located off-site
but will be affected by runoff from the development.
(9)
Municipal Liability Disclaimer. Approval of a stormwater management
plan by the Township shall not be construed as an indication that
said plan complies with the requirements, laws, or standards of any
agency of the commonwealth which may or may not govern said activity.
D.
Design
Criteria for Stormwater Detention Facilities. The following criteria
shall be utilized for the design of proposed detention facilities:
(1)
Detention facility(s) shall be designed such that the post-development
peak runoff rates from the developed site are controlled at levels
consistent with the allowable release rates determined for the one-,
two-, ten-, twenty-five-, fifty-, and one-hundred-year design storms.
(2)
All detention facilities shall be equipped with outlet structures
to provide discharge control for the one-, two-, ten-, twenty-five-,
fifty-, and one-hundred-year storm events. Provisions shall also be
made for auxiliary structures (e.g., emergency spillways) that are
capable of passing the unattenuated, post-development one-hundred-year
storm peak flows, presuming blockage of all lower flow controls, without
damaging the facilities. Open channel type emergency spillways shall
be designed at an elevation above the design one-hundred-year water
surface elevation for the facility.
(3)
Shared storage facilities, which provide stormwater detention
for more than one development site, will be encouraged. Such facilities
shall meet the design criteria contained in this Part. Runoff from
the development sites involved shall be conveyed to the facility in
a manner so as to avoid adverse impacts, such as flooding or erosion,
to channels and properties located between the development site and
the shared storage facilities.
(4)
Where detention facilities are used, the design of multiple-use
facilities, such as ballfields or similar recreational uses, are encouraged
wherever feasible. In addition to stormwater management, facilities
should, where appropriate, allow for recreational uses including play
areas, picnic grounds, etc. Consultation with the Township and prior
approval are required before design. Provision for permanent wet ponds
with stormwater management capabilities may also be appropriate.
(a)
Multiple use basins should be constructed so that potentially
dangerous conditions are not created.
(b)
Water quality basins or recharge basins that are designed for
a slow release of water or other extended detention ponds are not
permitted for recreational uses, unless the ponded areas are clearly
separated and secure.
(5)
As a general rule, detention facilities will be designed as
dry basins, although wet facilities will be considered in specific
situations where they can be shown to represent a significant amenity
or environmental benefit to the development and/or the Township. Facilities
should be designed to induce water depths as shallow as possible.
(6)
Except in approved wet basins, stormwater detention basins will
be designed to drain completely. A low-flow channel with a minimum
slope of 1% shall be installed to facilitate the conveyance of storm
sewer flows to the basin outlet during frequent storm events. All
interior portions of the basin will slope toward the outlet or low
flow channel at a minimum slope of 2% (SS-19). Except in approved
wet basins, all impoundment areas shall be adequately underdrained
to prevent long-term ponding of water.
(7)
Detention facility outfall pipes shall have a minimum of two
antiseepage collars installed along the profile of the pipe. Antiseepage
collars shall be constructed of reinforced concrete. Pipe bedding
material shall be specified to prohibit seepage along the pipe trench
and shall be in accordance with pipe manufacturer specifications (SS-20).
(8)
All detention facilities designed with an earthen dam shall
provide a minimum of one foot of freeboard between the peak emergency
spillway design flow elevation [§ 17-350.7D(2)] and the
top of the embankment.
(9)
Emergency spillways not excavated in existing ground shall be
designed with a suitable erosion protection lining approved by the
Township. Riprap spillways shall provide a concrete cutoff wall at
the spillway design crest elevation or grass-lined emergency spillway
from a detention pond (Drawings SS-21A and SS-21B).
(10)
All embankments will be designed according to sound engineering
practice for such structures and must meet the approval of the Township.
Facilities with a design water depth in excess of 10 feet may require
a supporting report from a geotechnical engineer and shall be constructed
under the supervision of the geotechnical engineer. In general, impoundment
areas shall be designed to be contained within areas excavated within
existing ground, rather than fill, whenever possible. Impoundment
areas designed within fill shall require a supporting report from
a geotechnical engineer addressing potential infiltration concerns
and recommended solutions.
(11)
A minimum embankment crest width of 10 feet shall be constructed
for all earthen fill embankments. The outside slopes of the embankment
shall not exceed two horizontal to one vertical. The interior slopes
of the facility within the pool area shall not exceed a slope of three
horizontal to one vertical. Design of facilities with flatter slopes
for aesthetics and as a maintenance consideration are encouraged (SS-16).
(12)
Except where special erosion protection measures are provided,
all disturbed areas will be graded evenly, topped with four inches
of topsoil, fertilized, seeded, and mulched by methods consistent
with PennDOT Publication 408. PennDOT Formula C or equivalent seed
mixtures containing crown vetch shall not be applied to the fill embankments
of stormwater management facilities. The placement of trees within
these areas shall also be prohibited.
(13)
All outfalls to and from the facility shall be provided with
endwalls and erosion control measures as per § 17-350.8C.
Where land use and topography are suitable, detention facility outfalls
to existing or constructed wetland areas will be encouraged to promote
the water quality benefits of such areas.
(a)
No outlet structure from a stormwater management facility or
swale shall discharge directly onto a Township or state roadway without
approval from the Township or PennDOT.
(14)
Outlet control structures shall be constructed of reinforced
concrete (cast-in-place or precast) and shall be recessed into the
embankment (SS-17). Trash racks for low-flow control openings should
be designed to provided four to 10 times the area of the low-flow
opening and to facilitate debris removal and maintenance (SS-18).
(15)
Access to all detention facilities shall be provided to the
Township for maintenance purposes. This access shall be via a minimum
ten-foot-wide gravel access road (SS-23) at a maximum grade of 15%
as necessary to access the facility location, and by a written statement
on recorded plans from the owner/operator of the facility granting
access to the Township as noted in § 17-350.7C(2)(g)5) (SS-23).
(16)
Detention facilities that are designed as sedimentation facilities
during construction operations shall be desilted and regraded to original
design dimensions and have all temporary sedimentation control devices
removed prior to their conversion to detention facilities. Low-flow
channels and underdrains should be installed with the conversion of
the facility.
(17)
In subdivisions or projects that are constructed in phases with
individual detention facilities employed as sedimentation basins,
said facilities shall be converted to their ultimate use as stormwater
management facilities as soon as their tributary areas are stabilized
per Butler County Conservation District standards. This conversion
may be requested by the Township, with supportive corroboration from
the Butler County Conservation District, and shall be implemented
as outlined in § 17-350.7D(16), and the approved erosion
and sedimentation control plan.
(18)
An as-built drawing shall be required for each stormwater detention
facility and BMP constructed. The drawing shall represent certification
of the volume of the facility and the depth versus storage relationship,
as well as the elevational relationships and dimensions of flow controls,
including emergency spillways as appropriate. These relationships
shall be shown on the drawing in table form or in report form. In
the event that these relationships vary from the computations provided
in the approved plan, revised storm routings may be required at the
discretion of the Township. Modifications to the stormwater management
facilities may be required by the Township based on the results of
these routings. Final submission of as-built drawings shall be in
accordance with § 17-350.3, and Appendix 17-B.[6]
[6]
Editor's Note: Appendix 17-B is included at the end of this chapter.
(19)
Inlets structures shall be recessed into the embankment except
when an alternative design is approved by the Township.
(20)
In addition to the requirements of the Code, underground detention
facilities shall meet the following minimum design standards:
(a)
Underground tank facilities shall utilize the largest practical
pipe diameter in order to provide ease of access for maintenance and
inspection.
(b)
Design measures to prevent pipe floatation and allow for visual
inspection capabilities, adequate pipe ventilation and access for
maintenance shall be provided.
(c)
Underground chambers or pipes shall be aligned parallel to the
contours.
(d)
A minimum of two separate accessways to the underground detention
facilities shall be provided for maintenance personnel.
(e)
The underground detention facilities shall be designed to include
overflow controls that either divert runoff via a flow splitter placed
at the facility entrance or an overflow weir/orifice system designed
in conjunction with the outlet of the facility.
(f)
Maximum life expectancy of the underground system shall also
be a design consideration for pipe material specifications.
(21)
Wet Basins. Existing ponds or permanent pool basins may be used
provided they meet the following requirements:
(a)
A report, prepared by a biologist, ecologist, or similarly qualified
professional, shall be submitted to the Township for review that evaluates
the design of the proposed wet basin's ability to meet the following
criteria:
1)
The minimum permanent pool level to be maintained shall provide
sufficient depth throughout the year to reduce the growth of unwanted
vegetation and mosquitoes.
2)
The pond is of sufficient size to allow the appropriate aquatic
community needed to maintain a healthy pond ecology.
3)
The design of a wet basin shall include the determination of
the proposed site's ability to support a viable permanent pool. The
design should take into account such factors as the required rate
and quality of dry weather inflow, the quality of stormwater inflow,
seasonal and longer-term variations in groundwater table, and effects
of suspected pollutant loadings.
(22)
In addition to other requirements of the Code, naturalized basins
shall meet the following requirements:
(a)
The interior slopes of the basin within the pool area shall
not exceed a slope of four horizontal to one vertical.
(b)
The perimeter of stormwater detention basins shall be curvilinear
so that from most edges of the basin the whole basin will not be in
view. The Township may permit a more traditionally shaped (oval or
rectangular) basin when conditions such as topography, parcel size,
or other site conditions warrant. When permitted, the basin shall
be designed in consultation with the Township to include a landscaped
island or peninsula large enough and appropriately placed to reduce
the perceived size of the basin.
(c)
All areas of the naturalized basin, including basin floors,
side slopes, berms, impoundment structures, or other earth structures,
shall be planted with suitable vegetation such as naturalized meadow
plantings or lawn grass specifically suited for stormwater basins.
The plantings shall provide a satisfactory continuous cover to all
areas of the basin and shall not interfere in the safe and efficient
function of the basin as determined by the Township.
(23)
Geological Assessment.
(a)
Soils investigation report, including boring logs, compaction
requirements, and recommendations for construction of detention basins.
(24)
Stormwater management facility bottom (or surface of permanent
pool) elevations must be greater than adjacent floodplain elevations
(FEMA or HEC-RAS analysis). If no floodplain is defined, bottom elevations
must be greater than existing ground elevations 50 feet from top of
stream bank in the facilities' vicinity.
(25)
Basin outflow culverts discharging into floodplains must account
for tailwater. Tailwater corresponding to the one-hundred-year floodplain
elevation must be used for all design storms, or the applicant may
elect to determine flood elevations of the adjacent watercourse for
each design storm. The floodplain is assumed to be 50 feet from top
of stream bank in areas where a floodway is not designated or no other
evidence is provided.
(26)
The invert of all stormwater management facilities and underground
infiltration/storage facilities shall be located a minimum of two
feet above the seasonal high groundwater table. The invert of stormwater
facilities may be lowered if adequate subsurface drainage is provided.
Flows from underdrains need not be accounted for in volume or rate
control calculations.
(27)
Whenever possible, the side slopes and basin shape shall be
amenable to the natural topography. Vertical side slopes and rectangular
basins shall be avoided whenever possible.
(28)
Landscaping and planting specifications must be provided for
all stormwater management basins and be specific for each type of
basin.
(a)
Minimal-maintenance, saturation-tolerant vegetation must be
provided in basins designed as water quality/infiltration BMPs.
(29)
Berms shall be constructed using soils that conform to the unified
soil classification of CH, MH, CL or ML. Soils used shall be tested
to determine its density analysis per ASTM 698. The embankments will
be constructed in a maximum of six-inch lifts. The lifts will each
be compacted to a density at least 98% of its maximum dry density.
Each layer of compacted fill shall be tested to determine its density
per ASTM 2922 or ASTM 3017. One test per 50 cubic yards of material
placed (at least one per layer) shall be performed by an independent
testing agency.
(30)
A cutoff and key trench of impervious material shall be provided
under all embankments four feet or greater in height. The cutoff trench
shall run the entire length of the embankment and tie into undisturbed
natural ground.
(31)
Compaction test reports shall be kept on file at the site and
be subject to review at all times with copies being forwarded to the
Township Engineer upon request.
(32)
Temporary and permanent grasses or stabilization measures shall
be established on the sides and base of all earthen basins within
15 days of construction.
E.
Design
Criteria for Collection/Conveyance Facilities.
(1)
As a general rule, no stormwater may be discharged to unprotected
areas such as hillsides or fills. Stormwater shall either be conveyed
to the nearest established stream channel, as approved by the Township,
or provided with an approved energy dissipation device. Conveyance
shall be by pipe or erosion protected ditch.
(2)
The design for culverts, pipes, and other stormwater conveyance
structures shall be consistent with the design of the other stormwater
management facilities. In the event that these structures are to be
permitted by PADEP or PennDOT, the design criteria required by the
state agency shall be utilized.
(3)
All sites shall be graded to provide drainage away from and
around structures, including on adjacent properties, to prevent potential
flooding damage.
(4)
Collection/conveyance facilities should not be installed parallel
and close to the top or bottom of major embankments to avoid the possibility
of embankment failure, with the exception of those facilities specifically
designed to prohibit stormwater runoff from eroding slopes or preventing
runoff from damaging downstream properties.
(5)
Stormwater shall be collected and conveyed from upslope areas
in a manner designed to prevent damage to downslope property(s) consistent
with appropriate engineering standards. This system shall be identified
by permanent easements, with the party responsible for ownership and
maintenance identified.
(6)
The design of storm sewer systems shall include evaluation of
inlet grate capacities, bypass flows, entrance losses, storm pipe
capacities, hydraulic grade line computations and outfall velocities,
as appropriate. The storm sewer system shall function as intended
under all these conditions for the required design storm as specified
in § 17-350.7B(2)(b).
(7)
Private stormwater may be connected to the public system pursuant
to Detail SS-15.
(8)
The stormwater management site plan shall included horizontal
alignment, vertical profiles, and cross sections of all open channels,
pipes, swales and other BMPs.
(9)
Stormwater drainage systems shall be provided in order to permit
unimpeded flow along natural watercourses, except as modified by stormwater
management facilities or open channels consistent with this Part.
(10)
When it can be shown that, due to topographic conditions, natural
drainageways on the site cannot adequately provide for drainage, open
channels may be constructed conforming substantially to the line and
grade of such natural drainageways. Work within natural drainageways
shall be subject to approval by PADEP under regulations at 25 Pa.
Code Chapter 105 through the joint permit application process, or
where deemed appropriate by PADEP, through the general permit process.
(11)
The design of facilities over karst shall include an evaluation
and implementation of measures to minimize adverse effects.
(12)
In curbed roadway sections, the maximum encroachment of water
on the roadway pavement shall not exceed half of a through travel
lane or one inch less than the depth of curb during the ten-year design
storm of five-minute duration. Gutter depth shall be verified by inlet
capture/capacity calculations that account for road slope and opening
area.
(13)
Horizontal alignment, vertical profiles and cross sections of
all open channels, pipes, swale and other BMPs shall be provided.
[Added by Ord. 2014-440, 1/30/2014]
F.
Disposal
of Stormwater from Roof, Foundation and Driveway Drains.
(1)
Individual lots that are required to provide for on-lot stormwater
management facilities per the stormwater management plan shall be
identified on the recorded plan(s) for the subdivision.
(2)
No roof, driveway or foundation drain shall be discharged onto the right-of-way of any street or the pavement of any street. Roof drains shall discharge to infiltration areas or vegetative BMPs to the maximum extent practicable. When it is more advantageous to connect directly to street or storm sewers, then the Township shall permit it on a case-by-case as per Subsections 6 and 6A. All residential dwellings not connected to a private or public stormwater collection and management system shall install a stormwater containment and disposal system at the direction of the Township in accordance with (SS-13). This system must be equipped with BMPs to address runoff quality if the development plan is not designed with a regional stormwater management facility containing BMPs. BMP measures shall be privately owned and maintained and must be implemented on the system on private property. Other acceptable methods of disposal include underground tanks, infiltration devices, storm sewers, water gardens, rain barrels, and grassed or other ground surfaces provided that adequate consideration is given to erosion protection, or any other method approved by the Township.
(3)
At no time will any roof, driveway or foundation drains be allowed
to be connected to the sanitary sewer line.
(4)
The use of splash blocks is permitted. The location of the splash
block discharge must be a minimum of five feet from foundations and
10 feet from the property line. Exceptions to this method may be permitted
in the instance of townhouses or similar structures where common property
lines exist. No stormwater runoff may be directed in such a manner
as to disturb or damage neighboring properties.
(5)
Houses located on the low side of the road can discharge drains
(minimum of four-inch diameter) to the rear of the lot to a point
of discharge onto a rock apron (size and dimensions to be specified)
not less than 10 feet from the adjacent neighboring property line
when the adjacent property has no development potential or there is
a body of water between the properties and, provided that said discharge
has been accounted for within the approved stormwater management plan
and the discharge does not impact downstream property owners.
(6)
Lots shall be graded in such a manner as to divert stormwater
runoff away from adjacent property and structures consistent with
appropriate engineering standards.
(7)
French drain systems and rainwater collection systems shall
be kept completely separate in all instances.
8.
Standard
Design Criteria.
A.
Storm Sewer Trench SS-01 Within ROW. All storm sewer pipe within
the right-of-way shall be installed in accordance with the standard
in SS-01, Typical Storm Trench Detail, where located under all proposed
pavements. Impervious area shall be installed in accordance with the
standard in SS-01A.
B.
Cradles and Reinforcements for Sewers. All cradles and reinforcements
for sewers shall be approved by the Engineer.
C.
Headwall/Endwall (SS-02). Concrete headwalls and splash aprons shall
be constructed in accordance with the construction standard in SS-02,
Standard Type D-W Endwall Detail, at the outfall of all storm sewers.
Where watercourses are piped and filled, concrete headwall and splash
aprons shall be constructed at both ends of the pipe. Riprap shall
be placed at endwalls in accordance with SS-02 as appropriate. Preformed
end-sections are an acceptable alternative with Township approval.
D.
Concrete Encasement and Anchors for Sewers. All concrete encasement
and anchors for sewers shall be approved by the Engineer. All storm
sewers laid at slopes of 20% or greater shall have concrete anchors
installed in accordance with SS-14.
E.
Connection for Drop Manholes. All connections for drop manholes shall
be approved by the Engineer.
F.
Storm Sewer Outfall Channels and Drainage Swales. Permissible velocities of various channel linings [vegetation, rock lined, riprap, gabions (SS-04), etc.] shall be in accordance with the most recent version of the Erosion and Sediment Pollution Control Program Manual published by the Pennsylvania Department of Environmental Protection. Storm sewer outfall channels shall be trapezoidal or triangular shape with side slopes not to exceed two horizontal one vertical (ratio). Storm sewer outfall channels shall be designed in accordance with Chapter 13 of the Pennsylvania Department of Transportation Design Manual Part 2, Publication 13, § 13.3, titled "Watercourse Erosion Protection." Where drainage swales or open channels are used, they shall be suitably designed for ease of maintenance.
(1)
Energy dissipators and/or level spreaders shall be installed
at points where pipes or drainageways discharge to or from basins.
Discharges to drainage swales shall be dissipated or piped to an acceptable
point.
G.
Springs. Any springs encountered during construction shall be piped
and connected to the storm sewer system or extended to a natural watercourse
as may be approved by the Engineer.
H.
Riprap. All riprap used for outlet protection, bank stabilization
or other means of protection shall be designed and installed in accordance
with specifications outlined in PennDOT Publications 408 and 72.
I.
Erosion and Sedimentation Control. Erosion and sedimentation control measures shall be designed and used during construction as per the approved plan from the Butler County Conservation District [Subsection 7C(1)(b)] and in accordance with details presented in the most recent version of the Erosion and Sediment Pollution Control Program Manual, Chapter 102, published by the Pennsylvania Department of Environmental Protection [25 Pa. Code, Chapter 102]. The following measures shall also be required by the Township in conjunction with the aforementioned plan:
(1)
Individual On-Lot Controls. Individual on-lot controls shall
be used for all residential lot development (SS-24).
(2)
Rock Construction Entrance. All individual residential lot development
shall employ a rock construction entrance for vehicular access to
the lot from paved roadways. The construction entrance shall be installed
in accordance with details provided in the most recent version of
the PADEP Erosion and Sediment Pollution Control Program Manual.
(3)
Slope Stabilization. All cut or fill slopes that exceed 10 feet
in vertical height and a 3:1 (h:v) slope shall be stabilized with
an erosion control blanket to prevent slope erosion and promote seed
growth in accordance with the most recent version of the PADEP Erosion
and Sediment Pollution Control Program Manual requirements. A detail
shall be included with the plans specifying the type of blanket and
installation procedures. Slopes shall be redressed with topsoil prior
to final stabilization to promote optimum growth of vegetation.
(4)
Energy Dissipators. All energy dissipators, such as riprap aprons,
plunge basins, etc., shall be designed based on outlet velocities
associated with the design storm for the subject outfall pipe.
(5)
Construction of temporary roadways (e.g., for utility construction,
timber harvesting, etc.) shall comply with all applicable standards
for erosion and sedimentation control and stream crossing regulations
under 25 Pa. Code, Chapters 102 and 105. The Erosion and Sedimentation
Control Plan shall be submitted to the Butler County Conservation
District for approval and shall address the following, as applicable:
(a)
Design of the roadway system, including haul roads, skid roads,
landing areas, trails, and storage and staging areas.
(b)
Runoff control structures (e.g., diversions, culverts, detention
ponds, etc.).
(c)
Stream crossings for both perennial and intermittent streams.
(d)
Access to public roadways, including design of rock construction
entrance for mud and debris control.
(e)
A remediation plan for restoring the disturbed area through
regrading, topsoil placement, reseeding, and other stabilization techniques,
as required.
(6)
The location of all erosion and sedimentation control facilities,
shown on a plan separate from the SWM site plan (typically an E&S
Plan).
(7)
Construction sequence.
(8)
Identification of short-term and long-term ownership, operations,
and maintenance responsibilities.
(9)
Notes and Statements:
(a)
A statement signed by the landowner acknowledging that the stormwater
BMPs are fixtures that cannot be altered or removed without prior
approval by the Township.
(b)
A statement referencing the operation and maintenance (O&M)
agreement and stating that the O&M agreement is part of the SWM
site plan.
(c)
A note indicating that record drawings will be provided for
all stormwater facilities prior to occupancy or the release of the
surety bond.
(d)
The following signature block for the municipality:
[Amended by Ord. No. 2022-506, 1/27/2022]
|
"(Municipal official or designee), on this date (signature date),
has reviewed and hereby certifies that the SWM site plan meets all
design standards and criteria of Municipal Ordinance No. (number assigned
to the ordinance)."
|
(e)
The following signature block for the Township Engineer or approved
Township representative reviewing the Stormwater Management Plan:
|
"I,__________, have reviewed this Stormwater Management Plan
in accordance with the Design Standards and Criteria of the Cranberry
Township Stormwater Management Ordinance."
|
J.
Prohibition Against Non-Stormwater Discharges. No person shall allow
or cause to allow discharges or deposition of foreign material into
the Township's separate storm sewer system or stormwater management
systems which are not composed entirely of stormwater, except discharges
allowed under a state or federal permit or as set forth below:
(1)
Prohibited Connections. The following connections to a Township
separate storm sewer system are prohibited:
(a)
Any drain or conveyance, whether on the surface or subsurface,
which allows any non-stormwater discharge including sewage, process
wastewater, and wash water to enter the separate storm sewer system,
and any connections to the storm drain system from indoor drains and
sinks.
(b)
Any drain or conveyance connected from a nonresidential land
use to the Township's separate storm sewer system that has not been
documented in plans, maps, or equivalent records, and approved by
the Township.
(2)
Discharges that may be allowed based on a finding by the Township
that the discharge(s) do not significantly contribute to pollution
of surface waters of the commonwealth are:
(a)
Discharges from firefighting activities.
(b)
Uncontaminated water from foundation or from footing drains.
(c)
Discharges from potable water sources, including dechlorinated
water line and fire hydrant flushing, if such discharges do not contain
detectable concentrations of total residual chlorine (TRC).
[Amended by Ord. No. 2022-506, 1/27/2022]
(d)
Flows from riparian habitats and wetlands.
(e)
Lawn watering.
(f)
Irrigation drainage.
(g)
Diverted stream flows and springs.
[Amended by Ord. No. 2022-506, 1/27/2022]
(h)
Pavement wash waters where spills or leaks of toxic or hazardous
materials have not occurred (unless all spill material has been removed)
and where detergents are not used.
(i)
Routine external building washdown (which does not use detergents
or other compounds).
(j)
Air-conditioning condensate.
(k)
Residential (i.e., not commercial) vehicle wash water where
cleaning agents are not utilized.
[Amended by Ord. No. 2022-506, 1/27/2022]
(l)
Noncontaminated hydrostatic test water discharges, if such discharges
do not contain detectable concentrations of TRC.
[Amended by Ord. No. 2022-506, 1/27/2022]
(m)
Uncontaminated groundwater.
(n)
Water from crawl space pumps.
(3)
In the event that the Township subsequently determines that any of the discharges identified within Subsection J(2) significantly contribute to pollution of waters of the commonwealth, or if so notified by DEP, then the Township will immediately notify the responsible person to cease the discharge or provide testing data that shows the discharge in question does not degrade the receiving stream characteristics as listed in 25 Pa. Code, Chapter 93.
(4)
Upon notice provided by the Township under Subsection J(3), the discharger will have a reasonable time, as determined by the Township, to cease the discharge consistent with the degree of pollution caused by the discharge.
(5)
Nothing in this section shall affect a discharger's responsibilities
under state law.
K.
Suggested Post-Construction Stormwater BMPs.
(1)
Innovative stormwater BMPs and recharge facilities are encouraged
(e.g., rooftop storage, drywells, cisterns, recreation area ponding,
diversion structures, porous pavements, holding tanks, infiltration
systems, in-line storage in storm sewers, and grading patterns). They
shall be located, designed, and constructed in accordance with the
latest technical guidance published by PADEP, provided that they are
accompanied by detailed engineering plans and performance capabilities
and supporting site specific soils, geology, runoff and groundwater
and infiltration rate data to verify proposed designs. Additional
guidance from other sources may be accepted at the discretion of the
Township Engineer (a preapplication meeting is suggested).
(a)
The following is a listing of detention and control methods
that may be used in stormwater management systems, if appropriate.
The choice of control techniques is not limited to those appearing
on this list.
1)
Detention/retention basins.
2)
Roof-top storage.
3)
Parking lot and street storage.
4)
Seepage pits, seepage trenches, level spreaders or other infiltration
structures.
5)
Bioretention areas.
6)
Porous payement and concrete lattice block surfaces.
7)
Grassed channels and vegetated strips.
8)
Routed flow over grass.
9)
Decreased impervious area coverage.
10)
Water quality storage volume in detention facilities.
(b)
The use of other control methods which meet the criteria in
this section shall be permitted when approved by the Township Engineer.
Various combinations of methods should be designed to suit the particular
requirements of the type of development and the topographic features
of the project area. Additional erosion and sedimentation control
design standards and criteria that must be applied where infiltration
BMPs are proposed include the following:
1)
Areas proposed for infiltration BMPs shall be protected from
sedimentation and compaction during the construction phase so as to
maintain their maximum infiltration capacity.
2)
Infiltration BMPs shall be protected from receiving sediment-laden
runoff.
3)
The source of protection for infiltration BMPs shall be identified
(i.e., orange construction fence surrounding the perimeter of the
BMP).
(2)
Infiltration. Prevention of stormwater runoff is the key objective
of 25 Pa. Code, Chapter 93, of the PADEP regulations since runoff
can change the physical, chemical, and biological integrity of waterbodies
thereby impacting water quality. All stormwater management plans shall
describe how these water quality protection requirements will be met.
(a)
Infiltration BMPs shall be evaluated and utilized to the maximum
extent possible to manage the net change in stormwater runoff generated
so that post-construction discharges do not degrade the physical,
chemical, and biological characteristics of the receiving waters.
These BMPs may be used to satisfy all or part of the requirements
in this subsection.
1)
Description of, justification, and actual field results for
infiltration testing with respect to the type of test and test location
for the design of infiltration BMPs.
(b)
Post-construction stormwater infiltration of runoff shall replicate
preconstruction infiltration of runoff to the maximum extent possible.
In calculating the recharge volume of runoff that can be infiltrated
at a site, the following methodology shall be used:
|
REv = [(S){0.05+0.009(I)}(A)]/12
| ||
|
Where
| ||
|
S
|
=
|
Soil specific recharge factor in inches (obtain from table below).
|
|
I
|
=
|
Impervious surface percentage.
|
|
A
|
=
|
Project area in acres.
|
|
REv, recharge volume, is computed in
acre-feet
| ||
|
Hydrologic Soil Group (HSG)
|
S
|
|---|---|
|
A
|
0.38
|
|
B
|
0.25
|
|
C
|
0.13
|
|
D
|
0.06
|
|
If more than one HSG is present at a site, a composite recharge
volume shall be computed based on the proportion of the total site
area within each HSG.
|
(c)
A detailed soils evaluation of the project site shall be performed to determine the suitability of infiltration BMPs. The evaluation shall be performed by a qualified professional and, at a minimum, address soil permeability, depth to bedrock, susceptibility to sinkhole formation, and subgrade stability. If infiltration is not a viable option on the subject site, the water quality storage option must be implemented as described in Subsection 8K(3).
(d)
All infiltration BMPs shall be located a minimum of 10 feet
away from the foundation wall of any structure.
(e)
Any infiltration BMP shall be capable of infiltrating the impounded
water within 48 hours.
1)
Unless specifically designed as a volume control or water quality
facility, all stormwater management facilities must empty over a period
of time not less than 24 hours and not more than 72 hours from the
end of the facility's inflow hydrograph. Infiltration tests performed
at the facility locations and proposed basin bottom depths, in accordance
with the BMP Manual, must support time-to-empty calculations if infiltration
is a factor.
(f)
The infiltration system shall have positive overflow controls
to prevent storage within one foot of the finished surface or grade.
(g)
Infiltration rates shall not be used in computing the storage
volume of the detention/retention system for the development.
(h)
Infiltration BMPs shall not be used in areas of known strip
mining or in limestone areas.
(3)
Water Quality Storage. In order to protect and maintain water
quality, additional stormwater runoff created by proposed developments
must be captured, stored, and treated. In addition, post-construction
stormwater infiltration of runoff must replicate preconstruction infiltration
of runoff to the maximum extent possible.
(a)
The volume of additional stormwater runoff to be captured, stored,
and treated is called the "water quality volume" (WQv). The formula for determining WQv is:
|
WQv = [(P){0.05+0.009(I)}(A)]/12
| ||
|
Where
| ||
|
P
|
=
|
Rainfall depth of 1-year storm = 1.13 inches.
|
|
I
|
=
|
Impervious surface percentage.
|
|
A
|
=
|
Drainage area in acres.
|
|
WQv is computed in acre-feet.
| ||
(b)
This volume is to be released over a twenty-four-hour extended
detention period. This calculation is to be performed as a separate
detention facility routing in the submitted stormwater management
report.
(c)
Meet the water quality goals of this Part by implementing measures
to:
1)
Minimize disturbance to floodplains, wetlands, natural slopes,
existing native vegetation and woodlands.
2)
Create, maintain, or extend riparian buffers and protect existing
forested buffers.
3)
Provide trees and woodlands adjacent to impervious areas whenever
feasible.
4)
Minimize the creation of impervious surfaces and the degradation
of waters of the commonwealth and promote groundwater recharge.
5)
Protect natural systems and processes (drainageways, vegetation,
soils, and sensitive areas) and maintain, as much as possible, the
natural hydrologic regime.
6)
Incorporate natural site elements (wetlands, stream corridors,
mature forests) as design elements.
7)
Avoid erosive flow conditions in natural flow pathways.
8)
Minimize soil disturbance and soil compaction.
9)
Minimize thermal impacts to waters of the commonwealth.
10)
Disconnect impervious surfaces by directing runoff
to pervious areas wherever possible and decentralize and manage stormwater
at its source.
(4)
Alteration of BMPs. No person shall modify, remove, fill, landscape,
or alter any existing stormwater BMP, including stormwater channels,
unless part of an approved maintenance program, without the written
approval of the Township.
L.
Best Management Practices (BMPs). The use of practical structural
and nonstructural BMPs will be encouraged by the Township in the design
of site drainage systems and land development. Design of such measures
shall consider the limitations of the site topography and soils, as
well as identify the benefits of proposed measures and maintenance
requirements. Technical requirements and limitations of BMPs are provided
in the Pennsylvania Handbook of Best Management Practices for Developing
Areas. The standard set forth in the most current version of this
document shall be considered the construction standards of this Part.
M.
Sensitive Areas and Stormwater Hotspots.
(1)
Sensitive Areas and Stormwater Hotspots: Sensitive areas and
water quality sensitive developments as defined below which require
special consideration with regard to stormwater management.
(a)
"Sensitive areas" are defined as those areas that, if developed,
have the potential to endanger a water supply. These areas consist
of the delineated one-year zone of contribution and direct upslope
areas tributary to the water supply wells. Municipalities may update
the sensitive area boundaries based on new research or studies as
required.
(b)
"Stormwater hotspots" are defined as a land development project
that has a high potential to endanger local water quality, and could
potentially threaten groundwater reservoirs. The Township Engineer
will determine what constitutes these classifications on a case-by-case
basis. The PADEP wellhead protection contaminant source list shall
be used as a guide in these determinations. Industrial manufacturing
site and hazardous material storage areas must provide NPDES SIC codes.
(2)
Performance Standards.
(a)
The location of the boundaries of sensitive areas is set by
drainage areas tributary to any public water supply. The exact location
of these boundaries as they apply to a given development site shall
be determined using mapping at a scale that accurately defines the
limits of the sensitive area. If the project site is within the sensitive
area (in whole or in part), two-foot contour interval mapping shall
be provided to define the limits of the sensitive area. If the project
site is adjacent to but within 500 linear feet of a defined sensitive
area, a five-foot contour interval map defining the limits of the
sensitive area shall be included in the stormwater management plan
to document the site's location relative to the sensitive area.
(b)
Stormwater hotspots may be required to prepare and implement
a stormwater pollution prevention plan and file notice of intent as
required under the provision of the EPA Industrial Stormwater NPDES
Permit Requirements.
(c)
Stormwater hotspots must use an acceptable pretreatment BMP
prior to volume control and/or rate control BMPs. Acceptable pretreatment
BMPs for these developments include those based on filtering, settling,
or chemical reaction processes such as coagulation.
N.
Protected Watershed Requirements.
(1)
For any regulated activity within a protected watershed (High
Quality or Exceptional Value), the applicant shall meet requirements
as contained in 25 Pa. Code, Chapter 93, as required and applicable.
(2)
An existing resources and site analysis plan shall be prepared
to provide the developer and the Township with a comprehensive analysis
of existing conditions, both on the proposed development site and
within 500 feet of the site. Conditions beyond the parcel boundaries
may be described on the basis of existing published data available
from governmental agencies and from aerial photographs. The Township
shall review the plan to assess its accuracy, conformance with Township
ordinances, and likely impact upon the natural and cultural resources
on the property. The following information shall be required:
(a)
Complete current perimeter boundary survey of the property to
be subdivided or developed prepared by a registered surveyor, showing
all courses, distances, and area and tie-ins to all adjacent intersections.
(b)
A vertical aerial photograph enlarged to a scale not less detailed
than one inch equals 400 feet, with the site boundaries clearly marked.
(c)
Natural features, including:
1)
Contour lines at intervals of not more than two feet. (Ten-foot
intervals are permissible beyond the parcel boundaries, interpolated
from USGS published maps.) Contour lines shall be based on information
derived from a topographic survey for the property, evidence of which
shall be submitted, including the date and source of the contours.
Datum to which contour elevations refer and references to known, established
benchmarks and elevations shall be included on the plan.
2)
Steep slopes in the following ranges: 15% to 25%; 25% and greater.
The location of these slopes shall be graphically depicted by category
on the plan. Slope shall be measured over three or more two-foot contour
intervals.
3)
Areas within the floodway, flood fringe, and approximated floodplain.
4)
Watercourses, either continuous or intermittent and named or
unnamed, and lakes, ponds or other water features as depicted on the
USGS Quadrangle Map, most current edition.
5)
Wetlands and wetland margins.
6)
Riparian buffers.
7)
Soil types and their boundaries, as mapped by the USDA Natural
Resource Conservation Service, including a table listing the soil
characteristics pertaining to suitability for construction and, in
unsewered areas, for septic suitability. Alluvial and hydric soils
shall specifically be depicted on the plan.
8)
Existing vegetation, denoted by type, including woodlands, hedgerows,
tree masses, tree lines, individual freestanding trees over six inches
DBH, wetland vegetation, pasture or croplands, orchards, permanent
grass land, old fields, and any other notable vegetative features
on the site. Vegetative types shall be described by plant community,
relative age, and condition.
9)
Any identified Pennsylvania Natural Diversity Inventory (PNDI)
site conflicts.
10)
Geologic formations on the tract, including rock
outcroppings, cliffs, sinkholes, and fault lines, based on available
published information or more detailed data obtained by the applicant.
(d)
Existing man-made features, including:
1)
Location, dimensions, and use of existing buildings and driveways.
2)
Location, names, widths, center-line courses, paving widths,
identification numbers, and rights-of-way of existing streets and
alleys.
3)
Location of trails that have been in public use (pedestrian,
equestrian, bicycle, etc.).
4)
Location and size of existing sanitary sewage facilities.
5)
Location and size of drainage facilities.
6)
Location of water supply facilities, including wellhead protection
areas.
7)
Any easements, deed restrictions, rights-of-way, or any other
encumbrances upon the land, including location, size, and ownership.
8)
Site features or conditions such as hazardous waste, dumps,
underground tanks, active and abandoned wells, quarries, landfills,
sandmounds, and artificial land conditions.
(e)
Total acreage of the tract, the adjusted tract area, where applicable,
and the constrained land area with detailed supporting calculations.
(3)
Stormwater Management System Concept Plan. A written and graphic
concept plan of the proposed post-development stormwater management
system shall be prepared and include:
(a)
Preliminary selection and location of proposed structural stormwater
controls;
(b)
Location of existing and proposed conveyance systems such as
grass channels, swales, and storm drains;
(c)
Location of floodplain/floodway limits;
(d)
Relationship of site to upstream and downstream properties and
drainages.
(e)
Preliminary location of proposed stream channel modifications,
such as bridge or culvert crossings.
(4)
Consultation Meeting. Prior to any stormwater management permit
application submission, the land owner or developer shall meet with
the Township for a consultation meeting on a concept plan for the
post-development stormwater management system to be utilized in the
proposed project. This consultation meeting shall take place at the
time of the preliminary plan or other early step in the development
process. The purpose of this meeting is to discuss the post-development
stormwater management measures necessary for the proposed project,
as well as to discuss and assess constraints, opportunities and potential
ideas for stormwater management designs before the formal site design
engineering is commenced.
(5)
All proposed regulated activities within a protected watershed
shall utilize, to the maximum extent possible, low-impact development
practices as contained in Appendix 17-B.[7]
(a)
The SWM plan and report shall address the following:
1)
Design using nonstructural BMPs:
a)
Lot configuration and clustering.
b)
Minimum disturbance.
i.
Define disturbance zones (excavation/grading) for
the site and individual lots to protect maximum total site area from
disturbance.
ii.
Barriers/flagging proposed to protect designated
nondisturbance areas.
iii.
Considered mitigative practices for minimal disturbance
areas (e.g., soil restoration).
iv.
Considered reforestation and revegetation opportunities.
2)
Apply structural BMP selection process that meets runoff quantity
and quality needs.
a)
Manage close to source with collection with conveyance
minimized.
b)
Consistent with site factors (e.g., soils, slope,
available space, amount of sensitive areas, pollutant removal needs).
c)
Minimize footprint and integrate into already disturbed
areas/other building program components (e.g., recharge beneath parking
areas, vegetated roofs).
d)
Consider other benefits such as aesthetic, habitat,
recreational and educational benefits.
e)
BMPs selection based on maintenance needs that fit
owner/users.
f)
BMPs sustainable using a long-term maintenance plan.
[7]
Editor's Note: Appendix 17-B is included at the end of this chapter.
O.
Riparian Buffer Requirements. Riparian buffers shall be provided
for any regulated activity to meet the requirements of 25 Pa. Code,
including Chapters 93, 96, and 102.
9.
SWM Site
Plan and Report Review.
A.
The Township shall require receipt of a complete SWM site plan and
report as specified in this Part. The Township shall review the SWM
site plan and report for consistency with the purposes, requirements,
and intent of this Part.
(1)
SWM site plans shall be of one size and in a form that meets
the requirements for recording in the Office of the Recorder of Deeds
of Butler County.
(a)
Plans for tracts of less than 20 acres shall be drawn at a scale
of one inch equals no more than 50 feet;
(b)
Plans for tracts of 20 acres or more, plans shall be drawn at
a scale of one inch equals no more than 100 feet;
(c)
Lettering shall be drawn to a size to be legible if the plans
are reduced to 1/2 size.
B.
The Township shall not approve any SWM site plan and report that
is deficient in meeting the requirements of this Part. At its sole
discretion and in accordance with this Part, when a SWM site plan
and report is found to be deficient, the Township may disapprove the
submission and require a resubmission, or in the case of minor deficiencies,
the Township may accept submission of modifications.
C.
The Township shall notify the applicant in writing within 45 calendar
days whether the SWM site plan and report is approved or disapproved
if the SWM site plan and report is not part of a subdivision or land
development plan. If the SWM site plan and report involves a subdivision
or land development plan, the timing shall follow the subdivision
and land development process according to the Municipalities Planning
Code.
D.
The Township shall not issue a building permit for any regulated
activity if the SWM site plan and report has been found to be inconsistent
with this Part, as determined by the Township. All required permits
from PADEP must be obtained prior to issuance of a building permit.
10.
Modification
of Plans.
A.
A modification to a submitted SWM site plan and report for a development
site that involves a change in stormwater management facilities or
techniques, or that involves the relocation or redesign of stormwater
management facilities, or that is necessary because soil or other
conditions are not as stated on the SWM site plan as determined by
the Township, shall require a resubmission of the modified SWM site
plan in accordance with this Part.
11.
Resubmission
of Disapproved SWM Site Plan and Report.
A.
A disapproved SWM site plan and report may be resubmitted with the
revisions addressing the Township's concerns documented in writing,
to the Township in accordance with this Part. The applicable Township
review fee must accompany a resubmission of a disapproved SWM site
plan and report.
12.
Authorization
to Construct and Term of Validity.
A.
The Township's approval of a SWM site plan and report authorizes
the regulated activities contained in the SWM site plan for a maximum
term of validity of five years following the date of approval. The
Township may specify a term of validity shorter than five years in
the approval for any specific SWM site plan. Terms of validity shall
commence on the date the Township signs the approval for a SWM site
plan. If stormwater management facilities included in the approved
SWM site plan have not been constructed, or if a record drawing of
these facilities has not been approved within this time, then the
Township may consider the SWM site plan disapproved and may revoke
any and all permits or approvals.
13.
Record
Drawings, Completion Certificate and Final Inspection.
A.
The applicant shall be responsible for providing record drawings
of all stormwater BMPs included in the approved SWM site plan. The
record drawing and an explanation of any discrepancies with the approved
SWM site plan shall be submitted to the Township as a prerequisite
for the release of the guarantee or issuance of an occupancy permit.
B.
The record drawing shall include a certification of completion signed
by a qualified professional verifying that all permanent stormwater
BMPs have been constructed according to the approved SWM site plan
and report.
(1)
Drawings shall show all approved revisions and elevations and
inverts to all manholes, inlets, pipes, and stormwater control facilities.
(2)
Submission shall include a comparison of the constructed stage-storage
(volume vs. elevation) of all aboveground and below ground stormwater
storage facilities to the approved design.
C.
After receipt of the record drawing and certification of completion
by the Township, the Township may conduct a final inspection.
14.
Financial
Guarantee.
A.
The applicant shall provide a financial guarantee to the Township
for the timely installation and proper construction of all stormwater
management controls as required by the approved SWM site plan and
this Part, equal to 110% of the full construction cost of the required
controls in accordance with the Municipalities Planning Code.
B.
At the completion of the project and as a prerequisite for the release
of the financial guarantee, the applicant shall:
(1)
Provide a certification of completion from an engineer, architect,
surveyor or other qualified person verifying that all permanent facilities
have been constructed according to the SWM site plan and report and
approved revisions thereto.
(2)
Provide a set of record drawings.
(3)
Request a final inspection from the Township to certify compliance
with this Part after receipt of the certification of completion and
record drawings by the Township.
15.
Suspension
and Revocation.
A.
Any approval or permit issued by the Township may be suspended or
revoked for:
(1)
Noncompliance with or failure to implement any provision of
the approved SWM site plan or operation and maintenance (O&M)
agreement.
(2)
A violation of any provision of this Part or any other applicable
law, ordinance, rule or regulation relating to the regulated activity.
(3)
The creation of any condition or the commission of any act during
the regulated activity which constitutes or creates a hazard or nuisance,
pollution, or which endangers the life or property of others.
C.
An approval that has been revoked by the Township cannot be reinstated.
The applicant may apply for a new approval under the provisions of
this Part.
D.
If a violation causes no immediate danger to life, public health
or property, at its sole discretion, the municipality may provide
a limited time period for the owner to correct the violation. In these
cases, the municipality will provide the owner, or the owner's designee,
with a written notice of violation and the time period allowed for
the owner to correct the violation. If the owner does not correct
the violation within the allowed time period, the municipality may
revoke or suspend any, or all, applicable approvals and permits pertaining
to any provision of this Part.
[Added by Ord. No. 2022-506, 1/27/2022]
16.
Waivers.
All waivers must be applied for or submitted at the same time as an
application for land development, subdivision, grading.
A.
The provisions of this Part are the minimum standards for the protection
of the public welfare.
C.
If an applicant for SWM plan and report approval demonstrates to
the satisfaction of the Township that a mandatory provision of the
Stormwater Management Ordinance is unreasonable or causes unique or
undue hardship, or that an alternate design may result in a superior
result in meeting the intent and purpose of the Stormwater Management
Act and the Township ordinances, the Township may, at its sole discretion,
grant a waiver to such provision if the requirements of this Section
are met.
D.
The applicant shall submit all requests for waivers in writing and
shall include such requests as a part of the plan review and approval
process. The applicant shall state in full the facts of unreasonableness
or hardship on which the request is based, the provision or provisions
of the ordinance that are involved, and the minimum waiver or relief
that is necessary. The applicant shall state how the requested waiver
and how the applicant's proposal shall result in an equal or better
means of complying with the intent or purpose and general principles
of this Part.
E.
The Township may grant applications for waivers when the following
findings are made, as relevant:
(1)
That the waiver shall result in an equal or better means of
complying with the intent of this Part.
(2)
That the waiver is the minimum necessary to provide relief.
(3)
That the applicant is not requesting a waiver based on cost
considerations.
(4)
That existing down gradient stormwater problems will not be
exacerbated.
(5)
That runoff is not being diverted to a different drainage area.
(6)
That increased flooding or ponding on off-site properties or
roadways will not occur.
(7)
That potential icing conditions will not occur.
(8)
That increase of peak flow or volume from the site will not
occur.
(9)
That erosive conditions due to increased peak flows or volume
will not occur.
(10)
That adverse impact to water quality will not result.
(11)
That increased one-hundred-year floodplain levels will not result.
(12)
That increased or unusual Township maintenance expenses will
not result from the waiver.
(13)
That the amount of stormwater generated has been minimized to
the greatest extent allowed.
(14)
That infiltration of runoff throughout the proposed site has
been provided where practicable, and predevelopment groundwater recharge
protected.
(15)
That peak flow attenuation of runoff has been provided.
(16)
That long-term operation and maintenance activities are established.
(17)
That the receiving streams and/or water bodies will not be adversely
impacted in flood-carrying capacity, aquatic habitat, channel stability
and erosion and sedimentation.
F.
The Township may charge a fee for each waiver request, which shall
be used to offset the administrative costs of reviewing the waiver
request. The applicant shall also agree to reimburse the Township
for reasonable and necessary fees that may be incurred by the Township
Engineer, Township Solicitor or other professional as the Township
deems necessary in any review of a waiver request.
G.
In granting waivers, the Township may impose reasonable conditions
that will, in its judgment, secure substantially the objectives of
the standards or requirements that are to be modified.
