[Ord. No. 2021-272, 3/2/2021]
1. For purposes of stormwater management, the Borough of New Stanton
is located entirely within the Sewickley Creek Watershed, which includes
the stormwater management performance district shown on the map entitled
"New Stanton Borough Performance District Map," which is hereby adopted
as a portion of this chapter. For areas not covered by a stormwater
performance district, the release rate shall be 80% of the predevelopment
peak flow as set by the Borough. For more information refer to www.westmorelandstormwater.org.
2. In areas not covered by a stormwater performance district, an 80%
release rate or less is established as a standard. This is to apply
a "factor of safety" to stormwater calculations; to account for the
many variables in site design and stormwater management; and to avoid
a land development project inadvertently increasing runoff and causing
harm downstream.
[Ord. No. 2021-272, 3/2/2021]
1. Preparation and implementation of a stormwater management (SWM) site
plan is required for all regulated activities, unless preparation
of a SWM site plan is specifically exempted.
2. Projects that propose greater than one acre of earth disturbance
are subject to NPDES permit requirements and will require a stormwater
management plan.
3. No regulated activities, unless exempted, shall commence until the
Borough of New Stanton issues written approval of a SWM site plan,
which demonstrates compliance with the requirements of this chapter.
4. Regulated development activities shall be as follows:
REGULATED DEVELOPMENT ACTIVITY TABLE
|
---|
Small lots < 20,000 square feet; large
lots > 20,000 square feet
|
---|
SWM Plan Requirement
|
New Impervious Area for New and Redevelopment
|
Disturbed Area*
|
Next Steps
|
---|
Exempt
|
0 square feet
|
Less than 1 acre
|
Comply with exemption section of this chapter
|
No-harm
|
Less than 1,000 square feet for small lots or 2,000 square feet
for large lots
|
Less than 3,000 square feet for Small Lots OR 5,000 square feet
for Large Lots
|
Comply with the no-harm section of this chapter
|
Waiver/modification/demonstrated equivalency
|
Less than 1 acre, subject to municipal approval
|
Less than 1 acre
|
Comply with the waiver/modification/demonstrated equivalency
section of this chapter
|
Small project (per definition), refer to Appendix C
|
1,000 square feet to 2,500 square feet for small lots or 2,000
square feet to 5,000 square feet for large lots
|
3,000 square feet to 5,000 square feet for Small Lots OR 5,000
square feet to 10,000 square feet for Large Lots
|
Submit small project site plan complete with all attachments
|
Stormwater Management Plan meeting the Ordinance requirements
|
Greater than 2,500 square feet for small lots or 5,000 square
feet for large lots if exempt and small project criteria are not met,
or if improvements do not meet no-harm criteria
|
Greater than 5,000 square feet for small lots or 10,000 square
feet for large lots
|
Consult a qualified professional to prepare a stormwater management
site plan
|
NOTES:
|
*
|
The above table is only applicable for projects with earth disturbance
less than one acre and that have not had cumulative impacts, within
five years preceding the permit application date, that are in excess
of the square foot limits.
|
[Ord. No. 2021-272, 3/2/2021]
1. The following regulated activities are specifically exempt from the
stormwater management plan preparation and submission requirements
articulated in this chapter:
A. Agricultural activity limited to plowing or tilling activities, for
animal concentrated (heavy) use areas provided the activities are
performed according to the requirements of Chapter 102, or conservation
practices being installed as part of the implementation of a conservation
plan written by an NRCS- or SCS-certified planner. This exemption
does not include any other type of earth disturbance subject to NPDES
permit requirements such as earth disturbance equal to or greater
than one acre.
B. A high tunnel, if proof is provided that the high tunnel is exempt
pursuant to the provisions of Act 15 of 2018. Such an exemption does
not exempt high tunnels from other requirements applicable under federal,
state or municipal laws.
C. Forest management and timber operations, provided the activities
are performed according to the requirements of Chapter 102.
D. Resource extraction activities, provided they are done in accordance
with applicable PA DEP regulations.
E. Roadway resurfacing and maintenance projects, which do not increase
impervious area, and underground infrastructure projects are exempt
from the provisions of this chapter, provided the activities meet
the requirements of all other municipal, state and federal requirements.
F. Domestic landscaping and/or vegetable gardening.
G. Voluntary green infrastructure (GI) or the retrofit of stormwater
management infrastructure as conversion to green infrastructure BMPs
to correct existing problems, that are solely intended to better manage
runoff from existing development, are not part of new development
or redevelopment, and that do not fall under the requirements of this
chapter or other development ordinances.
2. The Borough may deny or revoke any exemption pursuant to this section
at any time for any project that the Borough believes may pose a threat
to public health, safety, property or the environment.
[Ord. No. 2021-272, 3/2/2021]
1. Applicants may request approval of a "no-harm option" regarding stormwater
management for their project. No-harm option requests will be evaluated
based upon the following criteria deemed appropriate by the Borough
and in compliance with all commonwealth laws and regulations:
A. Project located very near or adjacent to the Sewickley Creek.
B. Project able to discharge directly into an existing flood-control
feature.
C. Project of a small size, less than the areas shown for the no-harm option in the Regulated Development Activity Table in §
26-302, Subsection
4, of this chapter.
D. Project will generate less than 0.2 cubic feet per second for small
lots and 0.35 cubic feet per second for large lots for the ten-year
storm peak rate increase as compared to predevelopment peak rate,
determined by a computation method acceptable to the Borough.
E. Project is not part of a larger development being piecemealed in
order to avoid stormwater management regulations.
F. Project is not part of a larger development which has grown piecemeal
over the past five years without stormwater management.
G. Project is less than 5% of a much larger site and is incidental to
the much larger site where the larger site already has a functioning
stormwater management system which is not causing stormwater runoff
or soil erosion problems.
H. Project is not located in a neighborhood, watershed, or location
where known stormwater problems exist, such as overland flooding like
flooding of structures or roadways.
I. Project does not discharge to a combined sewer.
J. Project will not degrade water quality of the receiving stream. Refer
to the Westmoreland County Integrated Water Resources Plan at www.westmorelandstormwater.org
for maps of impaired streams to determine if the project area is not
within an impaired stream corridor or provide documentation that further
degradation will not occur.
2. To qualify for the no-harm option, applicant may, at the request of the Borough, submit calculations, drawings, and details showing that the project meets the above criteria. Projects approved for the no-harm option may be exempted from constructing all or some of the usual stormwater management practices regularly required for similar projects. For projects not approved for the no-harm option, the applicant will be required to meet one of the other stormwater management (SWM) plan requirements under the Regulated Development Activity Table of Part
3 of this chapter.
3. No-harm requests shall be reviewed by the Municipal Engineer (and
the WCD if deemed necessary by the Borough) and, if determined to
be acceptable, shall be approved by the Borough.
[Ord. No. 2021-272, 3/2/2021]
1. If the Borough, in conjunction with the Borough Engineer, the WCD, or the DEP as applicable, determines that any requirement under this chapter cannot be achieved for a particular regulated activity, the Borough may, after an evaluation of alternatives, approve measures other than those in this chapter, subject to Subsections
2,
3 and
4 and in compliance with all commonwealth laws and regulations. The request for a waiver, modification, or demonstrated equivalency shall originate with the landowner, shall be in writing, include a study of downstream effects, and accompany the stormwater management plan submission to the Borough. The request shall provide the facts on which the request is based, the provision(s) of the ordinance involved and the proposed modification or demonstrated equivalency. The Borough Engineer and the WCD shall review the request to determine if it meets the requirements of this chapter, including Subsections
2,
3 and
4. If acceptable to the Borough and the WCD and the regulated stormwater activity involving earth disturbance is less than one acre, the Borough may grant the waiver or modification. If the regulated stormwater activity involving earth disturbance is equal to or greater than one acre, the plan will be subject to the NPDES requirements of DEP.
2. Waivers, modifications, or demonstrated equivalency of the requirements
of this chapter may be approved by the Borough if enforcement will
exact undue hardship because of unique physical circumstances or preexisting
site conditions peculiar to the land in question, provided that the
modifications or demonstrated equivalency will not be contrary or
detrimental to the public interest and shall achieve the intended
outcome, and that the purpose of this chapter is preserved. Hardship
must be due to such unique physical circumstances or preexisting site
conditions and not the circumstances or conditions generally created
by the provisions of this chapter; and there is no possibility that
the property can be developed in strict conformity with the provisions
of this chapter. Cost or financial burden shall not be considered
a hardship. Hardship cannot have been created by the landowner or
developer. Modification or demonstrated equivalency shall not substantially
or permanently impair the appropriate use or development of adjacent
property(s) not under the landowner's control. Modification or
demonstrated equivalency may be considered if an alternative standard
or approach will provide equal or better achievement of the purpose
of this chapter.
3. No waiver, modification or demonstrated equivalency of any regulated
stormwater activity involving earth disturbance greater than or equal
to one acre may be granted by the Borough unless that action is approved
in advance by the Department of Environmental Protection (DEP) or
the Westmoreland Conservation District (WCD).
4. Applicants may request approval of a demonstrated equivalent stormwater
activity for their project in lieu of performing traditional stormwater
management. Demonstrated equivalent stormwater activity requests will
be evaluated by the Borough Engineer and the WCD on a case-by-case
basis. Prior approval of a demonstrated equivalent stormwater activity
on a site does not set a precedent for future approval of the same
or other alternative activities on any site. The approval of a demonstrated
equivalent stormwater activity does not excuse the applicant from
following standard E&S and SWM practices as applicable on the
original site.
A. Demonstrated equivalent stormwater activities shall only be approved
when the following criteria are met:
(1)
Traditional stormwater management activities on the site are
precluded by a particular site limitation, such as contaminated soil,
steep slopes, existing buildings/infrastructure, combined sewer;
(2)
Construction of traditional stormwater management activities
on the site would require extra permits or lead to excessive permitting
activities and delays;
(3)
The site in question does not already have a stormwater management
problem; and
(4)
The site in question is not already contributing to water quality
problems in the receiving stream.
B. Approvable demonstrated equivalent stormwater activities may include
the following:
(1)
Restoration of an existing degraded wetland, stream channel,
floodplain, or riparian buffer, including daylighting of a stream.
(2)
Restoration, retrofit or upgrade an existing stormwater management
feature (inadequate detention pond, for example).
(3)
Creation of new stormwater management features, especially green
infrastructure, for a previously unmanaged site.
(4)
Provide a water-based benefit to the public other than stormwater
management (for example, extend a public sewer to an area not already
served).
(5)
Treatment of abandoned mine drainage.
C. The proposal for demonstrated equivalency shall be accompanied by
documentation or methodology quantifying the equivalency of the proposed
project to what would have been originally required. Acceptable documentation
or methodology may include use of the worksheets and checklist found
in PA DEP NPDES permit application, Appendix D or approved method showing the proposed equivalency:
(1)
Controls approximately the same amount of runoff volume as what
would originally have been proposed.
(2)
Improves approximately the same amount of runoff quality as
would have been originally proposed.
(3)
Is located within an impaired watershed or stream segment which
will benefit from the proposed project. Impairment may include stream
impairment, reduced stream buffer, and pollutant loading. Refer to
the Westmoreland County Integrated Water Resources Plan at www.westmorelandstormwater.org.
D. The demonstrated equivalent stormwater activity shall:
(1)
Be constructed concurrently with the project for which it is
being applied;
(2)
Be constructed according to plans approved by the Borough and
the WCD including any erosion control and stormwater management practices
as applicable;
(3)
Obtain all necessary permits;
(4)
Be located on land owned by or controlled by the applicant or
by a cooperating public or private entity(s) (school, church, club,
municipality, etc.);
(5)
Be protected by a perpetual easement or deed restriction, or
landowner agreement;
(6)
Be located in the same general watershed as the project for
which it is being applied; and
(7)
Have an operation and maintenance plan (O&M) specifying
the required operation and maintenance and who is responsible for
the required tasks.
[Ord. No. 2021-272, 3/2/2021]
1. When a regulated development activity creates new impervious area or total earth disturbance within the ranges of areas as indicated for a small project in the Regulated Development Activity Table (§
26-302, Subsection
4, of this chapter) the stormwater management requirements are as follows. Refer also to Appendix C.
2. For new impervious surfaces, the first two inches of runoff shall
be permanently removed from the runoff flow, and shall not be released
to waters of the commonwealth. Removal options include reuse, evaporation,
transpiration and infiltration.
3. Facilities, to the greatest extent possible and subject to Borough
approval, shall be designed to drain the permanently removed runoff
volume in a period no greater than 72 hours. Runoff volumes in excess
of two inches shall be safely conveyed to a stable vegetated area,
natural watercourse, the curb or gutter line of roadway or existing
storm collection/conveyance/control system as applicable.
4. This method is exempt from the requirements of §
26-402 of this chapter.
5. A small project stormwater management plan must be submitted to the Borough (and the WCD if deemed necessary by the Borough) and shall consist of the following items and related support material needed to determine compliance with §§
26-307 to
26-311 of this chapter. The applicant can also use protocols listed in Appendix C.
A. Narrative: General description of proposed stormwater management
techniques, including calculations, assumptions and criteria used
in the design of the stormwater management facilities and BMPs, and
construction specifications of the materials to be used for stormwater
management facilities and BMPs;
B. Stormwater Management Plan: Showing locations of all stormwater management
facilities and BMPs, especially green infrastructure, limits of disturbance,
including the type and amount of proposed impervious area, structures,
roads, paved areas and buildings;
C. Small project stormwater management worksheet;
D. Signed acknowledgement page for operation and maintenance of stormwater
facilities and BMPs (Refer to Appendix B); and
E. Erosion and Sediment Control Plan: including all reviews and letters
of adequacy from the Conservation District.
6. Small project requests shall be reviewed by the Municipal Engineer (and the WCD if deemed necessary by the Borough) and if determined to be acceptable, shall be approved by the Borough. Applicant is responsible, pursuant to §
26-706, to pay to the Borough the reasonable schedule of fees and expenses to cover the cost of review and report fees, including reasonable and necessary charges by the Borough's professional consultants.
[Ord. No. 2021-272, 3/2/2021]
1. Proposed land development must consider avoiding, minimizing, and
mitigating impacts to the site that may increase stormwater runoff
from the proposed project. Applied sequentially, these three low impact
development strategies should be an overall guide as a project is
planned and carried out.
2. The Westmoreland County Integrated Water Resources Plan provides
an online decisionmaking tool to assist developers, designers, property
owners in addressing all water resources during development and redevelopment
and should be consulted. Refer to www.paiwrp.com and www.westmorelandstormwater.org.
3. The following provisions shall be considered the overriding performance
standards against which all proposed stormwater control measures shall
be evaluated and shall apply throughout the Borough.
A. Any landowner and 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. For alteration or development taking place
in stages, the cumulative development must be used in determining
conformance with this chapter. Such measures shall include such actions
as are required:
(1)
To assure that the maximum rate of stormwater runoff is no greater
after development than prior to development activities as calculated
using the standards in this chapter for the twenty-four-hour duration
two-, ten-, twenty-five-, and 100-year storm frequencies. Rainfall
data shall be obtained from NOAA Atlas 14 or other source approved
by the Borough.
(2)
To manage the water quality, rate and volume and direction of
resulting stormwater runoff in a manner which otherwise adequately
protects health and property from possible injury.
(3)
To notify adjacent property owners or owners of affected properties
of any alteration or increase of stormwater flows.
B. Runoff treatment BMPs must be employed where necessary to ensure
the water quality, rate and volume requirements are met.
C. Volume control BMPs shall be used to maintain existing hydrologic
conditions for small storm events by promoting groundwater recharge
and/or evapotranspiration. Runoff volume controls shall be implemented
using the PA DEP Stormwater BMP Manual 2006 or other approved method
such as those listed in the following chart:
Acceptable Computation Methodologies for Stormwater Management
Plans:
|
---|
Method
|
Developed By
|
Applicability
|
---|
Win TR-20 (or commercial computer package based on TR-20)
|
USDA NRCS
|
Applicable where use of full hydrologic computer model is desirable
or necessary
|
Win TR-55 (or commercial computer package based on TR-55 i.e.
VT/PSUHM
|
USDA NRCS
|
Applicable for land development plans within limitations described
in TR-55
|
HEC-1, HEC-HMS
|
US Army Corps of Engineers
|
Applicable where use of full hydrologic computer model is desirable
or necessary
|
PennDOT 584 (based on rational method)
|
PennDOT
|
Applicable under standards established by PennDOT; not to be
used for runoff volume and pond sizing computations
|
EFH2
|
USDA NRCS
|
Applicable in agricultural areas subject to the program limits
|
SWMM
|
EPA
|
Applicable in urban and suburban areas subject to limits established
by EPA
|
PA DEP BMP Manual 2006
|
PA DEP
|
Applicable under standards established by PA DEP
|
Other methods
|
Varies
|
Other methodologies approved by the Borough
|
4. The project plan shall specify permanent stormwater BMPs to be implemented,
operated and maintained to meet legal water quality, rate and volume
requirements. If methods other than low-impact development (LID) and
green infrastructure methods are proposed to achieve the volume and
rate controls required under this chapter, the SWM site plan must
include a detailed justification demonstrating that the use of LID
and green infrastructure is not practicable.
5. In order to protect and maintain water quality, additional stormwater
runoff created by the development project 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 with the exception of hot spots. As a
minimum, this shall be a volume of additional runoff generated by
a two-year, twenty-four-hour storm. Preferred BMPs for hot spots include
storm inlet filters, proprietary stormwater quality devices, underground
detention tanks, detention ponds with forebays, tree planting, green
roof. Permeable pavement, infiltration BMPs, and rain gardens are
not recommended for hot spots.
6. In addition to the provisions set forth in Subsections
1 through
3, inclusive, as set forth above, all regulated development activities within the Borough shall be designed, implemented, operated and maintained to meet the purposes of this chapter, through these two elements:
A. Erosion and sediment control during the earth disturbance activities
(e.g., during construction).
B. Water quality, rate and volume protection measures after completion
of earth disturbance activities (e.g., post-construction stormwater
management), including operations and maintenance.
7. No regulated development activities within the Borough shall commence
until the requirements of this chapter are met.
8. All best management practices (BMPs) used to meet the requirements
of this chapter shall conform to the state water quality requirements,
and any more stringent requirements as determined by the Borough Engineer.
9. LID and green infrastructure techniques described in the PA DEP Stormwater
BMP Manual 2006 or most current edition are encouraged.
10. Projects proposed in municipalities which are subject to the MS4
regulations must comply with that Borough's approved MS4 permit,
including compliance with the six minimum control measures (MCMs)
and with the Borough's pollutant reduction plan (PRP).
[Ord. No. 2021-272, 3/2/2021]
1. The stormwater management performance standards in this chapter are
intended to implement the provisions, standards and criteria contained
in the Pennsylvania Storm Water Management Act (Act 167), 32 P.S.
§ 680.1 et seq. If there is any discrepancy between the
provisions of this chapter and the provisions, standards and criteria
of the Act, or if a stormwater management plan is subsequently approved
and adopted by the appropriate governmental agency or body, then the
provisions, standards and criteria of the current watershed plan shall
govern.
2. Management of stormwater runoff is the key objective of 25 Pa. Code
Chapter 93 of the DEP Regulations, because runoff can change the physical,
chemical and biological integrity of water bodies thereby impacting
rate, volume and water quality.
3. The project plan shall describe how these rate, volume and water
quality protection requirements will be met. 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 or biological characteristics
of the receiving waters. These BMPs may be used to satisfy all or
part of the requirements found within this chapter.
4. Refer to the Stormwater Performance Districts outlined in Appendix
A, and the Westmoreland County Integrated Water Resources
Plan (IWRP) at www.westmorelandstormwater.org. The project plan shall
describe how the proposed project will address performance standards,
impairments, and pollutant loading found in the IWRP. For areas not
covered by a stormwater performance district, the release rate shall
be 80% of the predevelopment peak flow as set by the Borough.
[Ord. No. 2021-272, 3/2/2021]
1. General Criteria.
A. Applicants may select runoff control techniques, or a combination
of techniques, which are most suitable to control stormwater runoff
from the development site. Refer to the Acceptable Computation Methodologies
Table of this chapter. All controls must be subject to approval of
the Borough Engineer and the WCD. The Borough Engineer may request
specific information on design and/or operating features of the proposed
stormwater controls in order to determine their suitability and adequacy
in terms of the standards of this chapter.
B. If the proposed development site is located in an impaired watershed
according to Category 4 of the PA Integrated Water Quality Monitoring
and Assessment Report, or in a watershed with a TMDL according to
Category 5 of the same report, the applicant shall identify the source
and cause of impairment and shall propose, if required or applicable
the use of BMPs to mitigate any impacts to the waters.
C. The applicant should consider the effect of the proposed stormwater
management techniques on any special soil conditions or geological
hazards which may exist on the development site. In the event such
conditions are identified on the site, the Borough Engineer may require
in depth studies by a competent geotechnical engineer. Not all stormwater
control methods may be advisable or allowable at a particular development
site.
D. The applicant shall consider the effect of the proposed stormwater
management techniques on existing stream impairments and pollutant
loading. Refer to the Westmoreland County Integrated Water Resources
Plan (IWRP) at www.westmorelandstormwater.org.
E. The applicant shall consider existing conditions on the site for
the prior five years to determine prevailing land use and impervious
cover, and shall consider 20% of existing impervious cover as meadow
for preexisting conditions on redevelopment sites.
F. The stormwater management practices to be used in developing a stormwater
management plan for a particular site shall be selected according
to the following order of preference:
(1)
Site planning for locating proposed buildings, impervious areas
and grading which minimizes disruption of the natural site characteristics
especially utilizing low-impact development techniques.
(2)
Minimization of impervious areas and promotion of retentive
grading.
(3)
Implementation of nonstructural measures (refer to the PA DEP
Stormwater BMP Manual 2006 or current edition).
(4)
Implementation of innovative/green infrastructure structural
measures (refer to the PA DEP Stormwater BMP Manual 2006 or current
edition).
(5)
Stormwater detention/retention structures.
G. Any BMP which is a dam, culvert, stream obstruction or encroachment
or outfall as defined in 25 Pa. Code Chapter 105 shall be designed
according to the requirements in those regulations.
H. Drainage easements shall be provided for all stormwater conveyance
and BMPs serving multiple properties and not located within a public
right of way. Easements shall include ingress and egress to a public
right of way, and shall be recorded at the county with the final plan.
Terms of easement shall prohibit excavation or placement of fill or
structures and any alteration that may adversely affect the flow of
stormwater within any portion of the easement.
I. No person shall install, create, modify, remove, fill, landscape
or otherwise alter or place any structure, soil, rock, material or
vegetation in or on, or otherwise adversely affect, any stormwater
management facility or any area within a stormwater easement without
the written approval of the Borough and approval of the WCD.
J. Persons engaged in land development activities shall provide the
required financial security and O&M agreements to the municipality
as outlined in the Appendix B.
2. Criteria for Stormwater Management Facilities and BMPs.
A. If stormwater management facilities and BMPs are utilized for the
development site, the facility(s) shall be designed such that post-development
peak runoff rates from the developed site are controlled to those
rates defined by a stormwater management performance district for
the twenty-four-hour duration two-, ten-, twenty-five-, and 100-year
storm frequencies. Rainfall data shall be obtained from NOAA Atlas
14 or other source as approved by the Borough.
B. All stormwater management facilities and BMPs shall be equipped with
outlet and overflow structures to provide rate discharge control for
the designated storm frequencies. Provision shall also be made to
safely pass the entire post-development 100-year storm without breaching
or otherwise damaging the facilities, downstream or neighboring properties.
C. Release of stormwater flow from a development site must be to an
existing stormwater conveyance or easement whether natural or man-made.
Calculations and information shall be presented as to the ownership,
responsible party, capacity, and stability of such conveyance. Release
of sheet flow as from a level spreader will be permitted on a case-by-case
basis as approved by the Borough and the WCD.
D. All stormwater management facilities and BMPs shall be designed to
control volume and water quality as defined by the stormwater management
performance district. Refer to Appendix A.
E. Shared stormwater management facilities and BMPs, which provide control
of runoff for more than one development site within a single subarea
may be considered and are encouraged. Such facilities shall meet the
criteria contained in this section. In addition, runoff from the development
sites involved shall be conveyed to the facility in a manner that
avoids adverse impacts (such as flooding or erosion) to channels and
properties located between the development site and the shared storage
facilities.
F. Where stormwater management facilities and BMPs will be utilized,
multiple use facilities, such as wetlands, lakes, ballfields or similar
recreational/open space uses are encouraged wherever feasible, subject
to the approval of the Borough.
G. Other considerations which shall be incorporated into the design
of the stormwater management facilities and BMPs include:
(1)
Inflow and outflow structures shall be designed and installed
to prevent erosion and embankments, cuts, fills and bottoms of impoundment
type structures should be protected from soil erosion.
(2)
Control and removal of debris both in the storage structure
and in inlet or outlet devices shall be a design consideration.
(3)
Inflow and outflow structures, pumping stations and other structures
shall be designed and protected, using safety benches, trash racks,
energy dissipaters and other means to minimize safety hazards.
(4)
Access may be restricted as specified by other New Stanton Borough
ordinance(s) relating to the provisions for fencing of swimming pools
and in appropriate instances such restriction of access may include
fencing in a minimum height of six feet.
(5)
Interior slopes of storage ponds shall not exceed a ratio of
three to one horizontal to vertical dimension with a combination of
interior and exterior slopes not exceeding five. Steeper slopes may
be approved by the Borough Engineer if documented to be stable by
a geotechnical analysis prepared by, or under the direction of, and
sealed by a licensed geotechnical engineer.
(6)
Pond principal spillways shall consist of a solid reinforced
concrete box (riser) that is designed and constructed to control the
flow rate out of the detention facility. Noncorrugated plastic pipe
may be used for the riser where the riser height is less than three
feet and the plastic pipe is properly anchored to prevent horizontal
or vertical displacement. The riser shall be joined by a watertight
connection to a horizontal reinforced concrete pipe or high-performance
polypropylene pipe (barrel) extending through the embankment and outletting
beyond the downstream toe of the fill. The capacity of the barrel
will be the 100-year post-development flow. The construction materials
must be approved by the Borough Engineer.
(7)
Pond dam embankments shall consist of all excavation on the
project, except such material as may be determined unsuitable by the
Borough Engineer, which includes but is not limited to frozen material,
organic material, rock in excess of three inches in diameter, construction
debris, sandy or other coarse-grained soils, noncompactable soils
and excessively wet or dry material. Acceptable material shall conform
to the current PennDOT Publication 408 section on embankment material
or shall be as approved by the Borough Engineer. The pond dam embankment
shall be compacted to a minimum 95% standard proctor maximum dry density
as per ASTM D698. The embankment shall be constructed and compacted
in maximum eight-inch lifts and the principle spillway outfall barrel
and anti-seep collar(s) shall be constructed integral with the dam
embankment construction.
(8)
Landscaping shall be provided for the facility which stabilizes
disturbed areas and preserves the natural and beneficial values of
the surrounding area. Landscaping shall consist of plant species native
to southwestern Pennsylvania. No trees or other woody vegetation shall
be planted on the fill areas of the pond dam embankment that may result
in loosening of the compacted soils of the embankment. Detention basin
bottoms shall be vegetated with a diverse native planting mix and
may include woody shrubs and meadow/wetland herbaceous plants. Noxious
and invasive plants that inhibit plant species diversity shall not
be included in the plant mix. PennDOT seed mix Formulas B, C, D and
L as per PennDOT Publication 408 latest revision, or approved equivalent
mix shall be used for revegetation of embankment areas. Crownvetch
and birdsfoot trefoil shall not be used due to their interference
with performance of inspections of the dam embankment. For other suitable
landscape plant species, refer to Appendix B of the Pennsylvania Stormwater
Best Management Practices Manual, latest edition.
(9)
Facility shall be located to facilitate maintenance, considering
the frequency and type of equipment that will be required.
(10)
Underground detention/retention/infiltration facilities shall
be equipped with open grate inlet or manhole access to facilitate
visual inspections.
(11)
Other considerations which should be incorporated into the design
of the detention facilities include the following:
(a)
Inflow and outflow structures shall be designed and installed
to prevent erosion, and bottoms of impoundment-type structures should
be protected from soil erosion.
(b)
All inflow structures into detention/retention ponds shall discharge
into a pond forebay designed in accordance with the Pennsylvania Stormwater
Best Management Practices Manual, where possible.
(c)
Control and removal of debris both in the storage structure
and in all inlet or outlet devices shall be a design consideration.
(d)
Inflow and outflow structures, pumping stations and other structures
shall be designed and protected to minimize safety hazards.
(e)
The water depth at the perimeter of a storage pond should be
limited to that which is safe for children. This is especially necessary
if bank slopes are steep or if ponds are full and recirculating in
dry periods. Restrictions of access (fence, walls, etc.,) shall be
necessary, depending on the location of the facility.
(f)
A safety bench with a minimum width of four feet shall be provided
around the entire interior perimeter of the pond at an elevation of
six inches minimum above the two-year peak water surface elevation
in the pond.
(g)
An anti-vortex device and trash rack shall be attached to the
top of the principal spillway to improve the flow of water into the
spillway and prevent floating debris from being carried out of the
basin.
(h)
The base of the principal spillway must be firmly anchored to
prevent its floating. Computations must be made to determine the anchoring
requirements. As a minimum, a factor of safety of 1.25 shall be used
(downward forces = 1.25 x upward forces).
(i)
The barrel of the principal spillway, which extends through
the embankment, shall be designed to carry the 100-year post-development
flow provided by the riser of the principal spillway with the water
level at the crest of the emergency spillway. The barrel shall consist
of a reinforced concrete pipe or high-performance polypropylene pipe
and shall be fully supported along its entire length by a concrete
cradle extending to the centerline of the pipe and projecting horizontally
a minimum of six inches beyond the outside wall of the pipe and vertically
six inches below the bottom of the pipe. The connection between the
riser and the barrel must be watertight. The outlet of the barrel
must be protected to prevent erosion or scour of downstream area.
This will include an end section or end wall with a designed riprap
apron. For principle spillway barrels that pass through compacted
fill pond dam embankments, the barrel, cradle and anti-seep collar(s)
shall be constructed integral with the dam embankment construction
as opposed to cutting into the completed dam embankment to construct
the barrel etc.
(j)
Anti-seep collars:
1)
Anti-seep collars shall be used on the barrel of the principal
spillway within the normal saturation zone of the embankment to increase
the seepage length by at least 10% if either of the following conditions
is met:
2)
The settled height of the embankment exceeds 10 feet.
3)
The embankment has a low silt clay content and the barrel is
greater than 10 inches in diameter.
4)
The anti-seep collars shall be installed within the saturated
zone. The maximum spacing between collars shall be 14 times the projection
of the collar above the barrel. Collars shall not be closer than two
feet to a pipe joint. Collars should be placed sufficiently far apart
to allow space for hauling and compacting equipment. Collars shall
consist of reinforced concrete with a minimum thickness of eight inches.
Connections between the collars and the barrel shall be watertight.
(k)
The emergency spillway shall consist of an open channel having
a control section at least 10 feet in length. The control section
is a level portion of the spillway channel at the highest elevation
in the channel. The emergency spillway shall be designed to carry
the peak rate of runoff expected from the entire post-development
100-year storm to the stormwater facility. The spillway channel shall
be located so as to avoid sharp turns or bends. The channel shall
return the flow of water to a defined channel downstream from the
embankment. At the discretion of the Borough Engineer and/or WCD,
the emergency spillway shall include a reinforced concrete grade control
wall extending perpendicular to the flow through the spillway with
the top of the wall flush with the spillway crest. This control wall
shall have a minimum width of eight inches, extend a minimum of 18
inches below the spillway crest and have a length no less than the
width of the emergency spillway opening at the top of dam. The emergency
spillway shall provide a minimum one foot of freeboard between the
water surface of the full 100-year post-development discharge through
the spillway and the top of the dam embankment.
3. Criteria for Collection/Conveyance Facilities.
A. All stormwater runoff collection or conveyance facilities, whether
storm sewers or other open or closed channels, shall be designed in
accordance with the following basic standards:
(1)
All building sites shall use measures to provide drainage away
from and around the structure in order to prevent any potential flooding
damage as much as practical. Such measures shall include grading the
surrounding lawn or pavement area so that it slopes away from the
structure by a minimum of 5% slope over a minimum distance of 10 feet;
raising the floor of the structure so that it is a minimum of six
inches above the predominate surrounding land elevation and above
the designated floodplain elevation for those located within a floodplain;
eliminating or waterproofing penetrations thru the structure's
walls or foundation; constructing berms, curbs, or swales to divert
surface water around the structure; arranging roof and area drains
to carry water away from the structure.
(2)
Developers proposing a land development or subdivision shall
arrange internal drainage within the subdivision so that surface water
is safely directed and channeled away from all structures within and
adjacent to the development site.
(3)
Developers shall provide to all persons constructing a structure
within a land development site, standards including drawings and specifications
to ensure that those persons adhere to the general site plans and
stormwater management plans for the development. Persons constructing
a structure within a land development site shall submit to the Borough
Engineer and the WCD drawings, calculations, and other information
when deemed necessary to show how they will meet the stormwater management
requirements of the development site.
(4)
Lots located on the high side or low side of streets shall extend
roof, trench and area drains to a stable vegetated area, natural watercourse,
the curb or gutter line of roadway or storm collection/conveyance/control
system (if applicable) in accordance with the approved stormwater
management plan for the development site.
(5)
For all building sites and lots, the inclusion of rain barrels,
rain gardens, drywells and other strategies for infiltration of roof
runoff close to its source is encouraged.
(6)
Collection/conveyance facilities should not be installed parallel
and less than 10 feet from the top or bottom of an embankment, nor
greater than or equal to 15 feet in height to avoid the possibility
of failing or causing the embankment to fail, unless documented to
be stable by a geotechnical analysis.
(7)
All collection/conveyance facilities shall be designed to convey
the twenty-five-year storm peak flow rate from the contributing drainage
area and to carry it to the nearest suitable outlet such as a stormwater
control facility, curbed street, storm sewer or natural watercourse.
However, the 100-year design storm may be required as determined by
the Borough Engineer where it is necessary for the storm system to
convey the 100-year design storm to the stormwater management facility.
(8)
Where drainage swales or open channels are used, they shall
be suitably lined to prevent erosion and designed to avoid erosive
velocities.
B. Wherever storm sewers are proposed to be utilized, they shall comply
with the following additional criteria:
(1)
Where practical, designed to traverse under seeded and planted
areas. If constructed within 10 feet of road paving, walks or other
surfaced areas, drains shall have a narrow trench and maximum compaction
of backfill to prevent settlement of the superimposed surface or development.
(2)
Preferably installed after excavating and filling in the area
to be traversed is completed, unless the drain is installed in the
original ground with a minimum of three feet cover and/or adequate
protection during the fill construction.
(3)
Designed:
(a)
With cradle when traversing fill areas of indeterminate stability.
(b)
With anchors when gradient exceeds 20%.
(c)
With encasement or special backfill requirements when traversing
under a paved area.
(4)
Designed to adequately handle the anticipated stormwater flow
and be economical to construct and maintain. The minimum pipe size
shall be 15 inches in diameter, with the exception of roof drains,
foundation drains or similar conveyance.
(5)
Drain pipe, trenching, bedding and backfilling requirements
and appropriate grates, catch basins, stormwater inlets, manholes
and other appurtenances shall conform to the requirements of the Borough
and/or applicable PennDOT specifications, Publication 408.
(6)
All corrugated metal pipe shall be polymer coated, and with
paved inverts where prone to erode. Pipe within a Borough right-of-way
shall be reinforced concrete pipe or high-performance polypropylene
pipe with a minimum diameter of 15 inches.
(7)
Storm inlets and structures shall be designed to be adequate,
bicycle-safe, self-cleaning and unobtrusive and consistent with Borough
standards with sufficient capture and conveyance capacity and spacing
of inlets and cleanouts for maintenance.
(8)
Where a proposed sewer or conveyance connects with an existing
storm sewer or conveyance system, the applicant shall demonstrate
that sufficient capacity exists in the downstream system to handle
the additional flow.
(9)
Storm sewer outfalls shall be equipped with energy dissipation
devices to prevent erosion and conform with applicable requirements
of the Pennsylvania DEP for stream encroachments (Section 7 of the
Dam Safety and Encroachments Act, 32 P.S. § 693.1 et seq.,
the rules and regulations promulgated thereunder at 25 Pa. Code § 105.441
to 105.449) and PA DEP Erosion and Sediment Control Manual (current
edition). Exit velocities of the design storm for the stormwater conveyance
systems must be considered in the design of the energy dissipation
devices.
(10)
Storm inlets shall include castings with the message "Dump No
Waste. Drains to Stream," or similar message as approved by the Borough
Engineer, cast into or permanently affixed to the casting and positioned
in a manner that is legible to pedestrian traffic.
4. Criteria for Riparian Buffers:
A. If a riparian buffer is required by PA DEP as part of an NPDES permit,
then DEP regulations will govern.
B. If a riparian buffer is used to meet stormwater management requirements
and/or MS4 pollutant load reduction credits it shall meet the following
requirements:
(1)
In order to protect and improve water quality, a riparian buffer
easement may be created and recorded as part of any subdivision or
land development that encompasses a riparian buffer.
(2)
Except as required by 25 Pa. Code Chapter 102, the riparian
buffer easement shall may be measured to a minimum of 35 feet measured
from the top of the nearest bank (on each side), or an average of
35 feet with no distance from top of bank less than 25 feet.
(3)
Minimum Management Requirements for Riparian Buffers:
(a)
Existing native vegetation shall be protected and maintained
within the riparian buffer easement.
(b)
Whenever practicable, invasive vegetation shall be actively
removed and the riparian buffer easement shall be planted with native
trees, shrubs and other vegetation to create a diverse native plant
community appropriate to the intended ecological context of the site.
(c)
There shall be no earth disturbance beyond which is necessary
to establish or maintain a planted buffer.
C. The riparian buffer easement shall be enforceable by the Borough
and shall be recorded in the appropriate County Recorder of Deeds
office, so that it shall run with the land and shall limit the use
of the property located therein. The easement shall allow for the
continued private ownership and shall count toward the minimum lot
area a required by zoning, unless otherwise specified in the Borough
Zoning Ordinance.
D. Any permitted use within the riparian buffer easement shall be conducted
in a manner that will maintain the extent of the existing 100-year
floodplain, improve or maintain the stream stability, and preserve
and protect the ecological function of the floodplain.
E. Stormwater drainage pipes and all other linear utility lines as approved
by the Borough shall be permitted within the riparian buffer easement,
but they shall cross the easement in the shortest practical distance.
Other stormwater management facilities and BMPs are not permitted
within the riparian buffer easement.
F. The following conditions shall apply when public and/or private recreation
trails are permitted within riparian buffers:
(1)
Trails shall be for nonmotorized use only.
(2)
Trails shall be designed to have the least impact on native
plant species and other sensitive environmental features.
G. Septic drain fields and sewage disposal systems shall not be permitted
within the riparian buffer easement and shall comply with setback
requirements established under 25 Pa. Code Chapter 73.
5. Criteria for Stream Restoration Project.
A. A stream restoration project may eligible for stormwater management
and/or MS4 load-reduction credits if it meets qualifying criteria
set by the Borough and as follows:
(1)
Existing conditions, such as channel or stream bank erosion
and an actively enlarging or incising urban stream condition, shall
be documented prior to restoration.
(2)
Projects should be located on first to third order (small) streams
to be effective.
(3)
Project should address a minimum of 100 linear feet of stream
channel and both sides where need to do so is evident.
(4)
Upstream impervious area should be sufficiently treated to address
peak flows that may exceed engineering design thresholds or compromise
channel form and function.
(5)
Utilize a comprehensive approach employing a mix of techniques
appropriate to the site, creating long-term stability of the streambed,
stream banks and floodplain.
(6)
Armored length of streams (i.e, using riprap or gabions) may
be used to maintain channel stability, but the same length shall not
be included in the load-reduction calculation.
(7)
Project shall maximize floodplain reconnection, with minimal
channel invert elevation increase (i.e., bank height ratio = 1.0 or
less) to achieve the objective.
(8)
Project shall include a minimum thirty-five-foot permanent riparian
buffer.
(9)
Project shall include an O&M plan identifying O&M activities,
frequencies and responsible parties.
[Ord. No. 2021-272, 3/2/2021]
1. No regulated development activities within the Borough shall commence
until approval by the Borough and the WCD of an erosion and sediment
control plan for construction activities.
2. Any earth disturbance activity of 5,000 square feet or more requires
an erosion and sedimentation control plan under 25 Pa. Code § 102.4(b).
Refer to the PA DEP Erosion and Sediment Pollution Control Manual
2012 or most recent version.
3. In addition, under 25 Pa. Code Chapter 92, a DEP NPDES construction
activities permit is required for regulated development activities
involving one acre or more of disturbance.
4. Evidence of any necessary permit(s) for regulated development activities from the appropriate DEP regional office or Westmoreland Conservation District must be provided to the Borough. The issuance of an NPDES construction permit [or permit coverage under the Statewide General Permit (PAG-2)] may satisfy the requirements under Subsection
1. upon review and approval by the Borough.
5. A copy of the erosion and sediment control plan and any permit required
by DEP or the Borough shall be available at the project site at all
times.
[Ord. No. 2021-272, 3/2/2021]
1. No regulated development activities which require Chapter 105 (Water
Obstructions and Encroachment) permit from either PA DEP or Westmoreland
Conservation District shall commence until all permits have received
PA DEP or WCD approval, and Borough approval.
2. Evidence of any necessary Chapter 105 permit from PA DEP/WCD shall
be provided to the Borough.
3. Proposed development shall avoid the long- and short-term adverse
impacts associated with the occupancy and modification of floodplains
as designated by FEMA, to the extent possible wherever there is a
practicable alternative in order to reduce the risk of flood loss,
minimize the impacts of floods on human safety, health and welfare,
and restore and preserve the natural and beneficial values served
by floodplains.
4. Any proposed development found to be within the base floodplain of
a waterway shall include the identification of impacts, an evaluation
of practicable alternatives outside the floodplain, and when impacts
cannot be avoided, the development of measures to minimize the impacts
and restore and preserve the floodplain as appropriate. Findings shall
be presented at a public meeting and a determination made by the Council
of the Borough of New Stanton.
5. Any proposed stormwater management plan should be consistent with
the provisions of the Pennsylvania Flood Plain Management Act 166
of 1978 and applicable Borough floodplain ordinances.