The City of Monessen is located in the Monongahela River Watershed,
which is not included in a Stormwater Management Performance District.
As recommended by the Westmoreland Conservation District for areas
not covered by a Stormwater Performance District, the release rate
shall be 80% of the pre-development peak flow as set by the City of
Monessen. For more information refer to www.westmorelandstormwater.org.
A.
Preparation and implementation of a stormwater management site plan
is required for all regulated activities unless preparation of a SWM
site plan is specifically exempted.
B.
Projects that propose greater than one acre of earth disturbance
are subject to NPDES permit requirements and will require a stormwater
management plan.
C.
No regulated activities, unless exempted, shall commence until the
municipality issues written approval of an SWM plan, which demonstrates
compliance with the requirements of this chapter.
D.
Regulated development activities shall be as follows:
|
Regulated Development Activity Table
| |||
|---|---|---|---|
|
SWM Plan Requirement
|
New Impervious Area for New and Redevelopment
|
Disturbed Area*
|
Next Steps
|
|
Exempt
|
0
|
Less than 1 acre
|
Comply with exemption section of this chapter[1]
|
|
No-harm
|
500 square feet or less
|
2,500 square feet or less
|
Comply with no-harm section of this chapter[2]
|
|
Waiver/modification/demonstrated equivalency
|
Less than 1 acre, subject to municipal approval
|
Less than 1 acre
|
Comply with waiver/modification/demonstrated equivalency section
of this chapter[3]
|
|
Small project (per definition), refer to Appendix C[4]
|
501 square feet to 3,000 square feet
|
2,501 to 5,000 square feet
|
Submit small project site plan complete with all attachments
|
|
Stormwater management plan meeting this chapter requirements
|
Greater than 3,000 square feet
|
Greater than 5,000 square feet
|
Consult a qualified professional
|
|
*
|
The above table is only applicable for new development or redevelopment
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.
|
A.
The following regulated activities are specifically exempt from the
stormwater management plan preparation and submission requirements
set forth in this chapter:
(1)
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,[1] 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.
[1]
Editor's Note: Said appendixes are included as attachments to this chapter.
(2)
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.
(3)
Forest management and timber operations provided the activities are
performed according to the requirements of Chapter 102.
(4)
Resource extraction activities provided they are done in accordance
with applicable PA DEP regulations.
(5)
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.
(6)
Domestic landscaping and/or vegetable gardening.
(7)
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
or other development ordinances.
B.
The City of Monessen may deny or revoke any exemption pursuant to
this section at any time for any project that the City of Monessen
believes may pose a threat to public health, safety, property or the
environment.
A.
Applicants may request approval of a no-harm option regarding stormwater
management for their project. No-harm option requests must meet the
following criteria deemed appropriate by the City of Monessen and
in compliance with all commonwealth laws and regulations:
(1)
Project located near or adjacent to significantly larger body of
water.
(2)
Project able to discharge directly into existing flood control feature.
(3)
Project of a small size: 500 square feet or less of new impervious surface or 2,500 square feet or less of land use changes. Refer to the Regulated Development Activity Table in Article III this chapter.
(4)
Project will generate less than 0.5 cubic foot per second for the
ten-year storm peak rate increase as compared to pre-development peak
rate.
(5)
Project is not part of a larger development being piecemealed in
order to avoid stormwater management regulations.
(6)
Project is not part of a larger development which has grown piecemeal
over the past five years without SWM.
(7)
Project is a small percentage (less than 5%) of a much larger site
and is incidental to the much larger site.
(8)
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.
(9)
Project does not discharge to a combined sewer.
(10)
Project will not degrade water quality of the receiving stream.
Refer to the Westmoreland County Integrated Water Resources Plan 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.
B.
To qualify for the no-harm option, the applicant may, at the request
of the municipality, 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. To be approved, no-harm requests must be reviewed and approved
by both the City Engineer and by the WCD, but final approval rests
with the City of Monessen.
A.
If the City of Monessen, in conjunction with the City Engineer, WCD, or DEP as applicable, determines that any requirement under this chapter cannot be achieved for a particular regulated activity, the City may, after an evaluation of alternatives, approve measures other than those in this chapter, subject to Subsections B, C and D 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 City. The request shall provide the facts on which the request is based, the provision(s) of this chapter involved and the proposed modification or demonstrated equivalency. The City Engineer and WCD shall review the request to determine if it meets the requirements of this chapter including Subsections B, C and D. If acceptable to the City and WCD, and the regulated stormwater activity involving earth disturbance is less than one acre, the City 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.
B.
Waivers, modifications, or demonstrated equivalency of the requirements
of this chapter may be approved by the City if enforcement will exact
undue hardship because of unique physical circumstances or pre-existing
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 pre-existing
site conditions and not the circumstances or conditions generally
created by the provisions of the Stormwater Management Ordinance;
and there is no possibility that the property can be developed in
strict conformity with the provisions of the Stormwater Management
Ordinance. 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.
C.
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 City unless that action is approved
in advance by the Department of Environmental Protection (DEP) or
the Westmoreland Conservation District (WCD).
D.
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 City 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.
(1)
Demonstrated equivalent stormwater activities shall only be approved
when the following criteria are met:
(a)
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;
(b)
Construction of traditional stormwater management activities
on the site would require extra permits or lead to excessive permitting
activities and delays;
(c)
The site in question does not already have a stormwater management
problem; and
(d)
The site in question is not already contributing to water quality
problems in the receiving stream.
(2)
Approvable demonstrated equivalent stormwater activities may include
the following:
(a)
Restoration of an existing degraded wetland, stream channel,
floodplain, or riparian buffer, including daylighting of a stream.
(b)
Restoration, retrofit or upgrade of an existing stormwater management
feature (inadequate detention pond, for example).
(c)
Creation of new stormwater management features, especially green
infrastructure, for a previously unmanaged site.
(d)
Provide a water-based benefit to the public other than stormwater
management (for example, extend a public sewer to an area not already
served).
(e)
Treatment of abandoned mine drainage.
(3)
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 E[1] or approved method showing the proposed equivalency:
(a)
Controls approximately the same amount of runoff volume as what would
originally have been proposed.
(b)
Improves approximately the same amount of runoff quality as would
have been originally proposed.
(c)
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 website www.westmorelandstormwater.org.
[1]
Editor's Note: Said appendix is included as an attachment to this chapter.
(4)
The
demonstrated equivalent stormwater activity shall:
(a)
Be constructed concurrently with the project for which it is being
applied;
(b)
Be constructed according to plans approved by the municipality and
the WCD including any erosion control and stormwater management practices
as applicable;
(c)
Obtain all necessary permits;
(d)
Be located on land owned by or controlled by the applicant or by
a cooperating public or private entity or entities (school, church,
club, municipality, etc.);
(e)
Be protected by a perpetual easement or deed restriction, or landowner
agreement;
(f)
Be located in the same general watershed as the project for which
it is being applied; and
(g)
Have an operation and maintenance plan (O&M) specifying who is
responsible for what tasks.
A.
When a regulated development activity (refer to Table in § 338-15 of this chapter) creates impervious area between 501 and 3,000 square feet, or total earth disturbance of 2,501 to 5,000 square feet the stormwater management requirements are as follows. Refer also to Appendix C.[1]
[1]
Editor's Note: Said appendix is included as an attachment to this chapter.
B.
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.
C.
Facilities, to the greatest extent possible and subject to City 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.
E.
A small project stormwater management plan must be submitted to the City of Monessen and the WCD and shall consist of the following items and related support material needed to determine compliance with §§ 338-20 to 338-24 of this chapter. The applicant can also use protocols listed in Appendix C.[2]
(1)
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;
(2)
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;
(3)
Small project stormwater management worksheet for each BMP proposed;
(4)
Signed agreement page for operation and maintenance of stormwater
facilities and BMPs (Refer to Appendix C)[3]; and
[3]
Editor's Note: Said appendix is included as an attachment to this chapter.
(5)
Erosion and sediment control plan including all reviews and letters
of adequacy from the Conservation District.
[2]
Editor's Note: Said appendix is included as an attachment to this chapter.
A.
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.
B.
The Westmoreland County Integrated Water Resources Plan provides
an online decision- making tool to assist developers, designers, property
owners in addressing all water resources during development and redevelopment
and should be consulted. Refer to website www.paiwrp.com and website
www.westmorelandstormwater.org.
C.
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 City of Monessen.
(1)
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:
(a)
To assure that the maximum rate of stormwater runoff is no greater
after development than prior to development activities for the two-,
ten-, fifty-, and 100-year storms. Rainfall data shall be obtained
from NOAA Atlas 14, the E&S manual, Table 5.1 for NRCS calculations,
and PennDOT Publication 584, Chapter 7, Appendix A for Rational Method
calculations, or other source approved by the municipality.
(b)
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.
(c)
To notify adjacent property owners or owners of affected properties
of any alteration or increase of stormwater flows.
(2)
Runoff treatment BMPs must be employed where necessary to ensure
the water quality, rate and volume requirements are met.
(3)
Volume control BMPs shall be used to maintain existing hydrologic
conditions for small storm events by promoting groundwater recharge
and/or evapotranspiration. For the two-year storm event, runoff volume
controls shall be implemented using the PA DEP Stormwater BMP Manual
2006. For all other storm events use an 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 ie.
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
|
|
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
|
Submit the methodology to the City for review and approval
|
D.
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 plan must include
a detailed justification demonstrating that the use of LID and green
infrastructure is not practicable.
E.
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 a hot spot 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 hotspots.
F.
G.
No regulated development activities within the City of Monessen shall
commence until the requirements of this chapter are met.
H.
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 City of Monessen.
I.
LID and green infrastructure techniques described in the PA DEP Stormwater
BMP Manual 2006 or most current edition are encouraged.
J.
Projects must comply with the City's approved MS4 permit, including
compliance with the six minimum control measures (MCMs) and with the
City's pollutant reduction plan (PRP).
A.
The stormwater management performance standards in this chapter are
intended to implement the provisions, standards and criteria contained
in the Pennsylvania Stormwater 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.
B.
Management of stormwater runoff is a key objective of 25 Pa. Code Chapter 93 of the DEP Regulations, because runoff can change the physical, chemical, and biological integrity of waterbodies thereby impacting rate, volume and water quality.
C.
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.
D.
Refer to the Stormwater Performance Districts outlined in Appendix
A,[1] 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. The release
rate shall be 80% of the pre-development peak flow as set by the City
of Monessen.
[1]
Editor's Note: Said appendix is included as an attachment to this chapter.
A.
General criteria.
(1)
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[1] of this chapter. All controls must be subject to approval
of the City Engineer and the WCD. The City 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.
(2)
If the proposed development site is located in an impaired water
shed 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.
(3)
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 City 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.
(4)
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.
(5)
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 pre-existing conditions on redevelopment sites.
(6)
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:
(a)
Site planning for locating proposed buildings, impervious areas
and grading which minimizes disruption of the natural site characteristics
especially utilizing low-impact development techniques.
(b)
Minimization of impervious areas and promotion of retentive
grading.
(c)
Implementation of nonstructural measures (refer to the PA DEP
Stormwater BMP Manual 2006 or current edition).
(d)
Implementation of innovative/green infrastructure structural
measures (refer to the PA DEP Stormwater BMP Manual 2006 or current
edition).
(e)
Stormwater detention/retention structures.
(7)
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.
(8)
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.
(9)
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 City of Monessen and approval of the WCD.
(10)
Persons engaged in land development activities shall provide
the required [financial security, O&M Agreements] to the [municipality]
as outlined in the Appendix B.[2]
[2]
Editor's Note: Said appendix is included as an attachment to this chapter.
B.
Criteria for stormwater management facilities and BMPs.
(1)
If stormwater management facilities and BMPs are utilized for the
development site, the facilities shall be designed such that post-development
peak runoff rates from the developed site are controlled to the 80%
release rate for the two-, ten-, fifty- and 100-year storm frequencies.
Rainfall data shall be obtained from NOAA Atlas 14 or other source
as approved by the municipality.
(2)
All stormwater management facilities and BMPs shall be equipped with
outlet/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.
(3)
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, when it is the only option
available will be permitted on a case-by-case basis as approved by
the municipality and WCD.
(4)
All stormwater management facilities and BMPs shall be designed to
control volume and water quality as defined by 80% release rate for
the two-, ten-, fifty- and 100-year storm frequencies.
(5)
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.
(6)
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 City of Monessen.
(7)
Other considerations which shall be incorporated into the design
of the stormwater management facilities and BMPs include:
(a)
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.
(b)
Control and removal of debris both in the storage structure
and in inlet or outlet devices shall be a design consideration.
(c)
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.
(d)
In appropriate instances as determined by the City, access may
be restricted to include fencing in a minimum height of seven feet.
(e)
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.
(f)
Landscaping shall be provided for the facility which stabilizes
disturbed areas and preserves the natural and beneficial values of
the surrounding area. Woody vegetation shall not be located or planted
on a BMP dam.
(g)
Facility shall be located to facilitate maintenance, with an
associated easement of adequate area considering the frequency and
type of equipment that will be required.
(h)
Underground detention/retention/infiltration facilities with
an associated easement of adequate area shall be equipped with open
grate inlet or manhole access to facilitate visual inspections.
C.
Criteria for collection/conveyance facilities.
(1)
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:
(a)
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 a minimum
of one foot above the base flood elevation in a floodplain; eliminating
or waterproofing penetrations through 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 and to a stormwater BMP. Connection
to a sanitary sewer is not allowed.
(b)
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 to stormwater BMP.
(c)
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 municipal
engineer and WCD drawings, calculations, and other information to
show how they will meet the stormwater management requirements of
the development site.
(d)
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.
(e)
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 required unless soil conditions prohibit
their use.
(f)
Collection/conveyance facilities should not be installed parallel
less than 10 feet from the top or bottom of an embankment, 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.
(g)
All collection/conveyance facilities shall be designed to convey
the 100-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.
Where feasible avoid discharging into combination sewers in the CS4
District. Refer to Appendix A.[3]
[3]
Editor's Note: Said appendix is included as an attachment to this chapter.
(h)
Where drainage swales or open channels are used, they shall
be suitably lined to prevent erosion and designed to avoid erosive
velocities.
(2)
Wherever storm sewers are proposed to be utilized, they shall comply
with the following additional criteria:
(a)
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.
(b)
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 of cover and/or adequate
protection during the fill construction.
(c)
Designed:
[1]
With cradle when traversing fill areas of indeterminate stability.
[2]
With anchors when gradient exceeds 20%.
[3]
With encasement or special backfill requirements when traversing
under a paved area.
[4]
With encasement when installing within 18 inches vertical and
five feet horizontal of a utility line or below a nearby sewer line.
[5]
All joints to be soil or watertight.
(d)
Designed to adequately handle the anticipated stormwater flow
and be economical to construct and maintain. The minimum pipe size
shall be 18 inches in diameter, with the exception of roof drains,
foundation drains or similar conveyance.
(e)
Drainpipe, trenching, bedding and backfilling requirements and
appropriate grates, catch basins, stormwater inlets, manholes and
other appurtenances shall conform to the requirements of the City
and/or applicable PennDOT specifications, Publication 408.
(f)
All corrugated metal pipe shall be polymer coated, and with
paved inverts where prone to erode. Pipe within a municipality right-of-way
shall be reinforced concrete pipe or high-performance polypropylene
pipe with a minimum diameter of 18 inches.
(g)
Storm inlets and structures shall be designed to be adequate,
safe, self- cleaning and unobtrusive and consistent with municipality
standards with sufficient capture and conveyance capacity and spacing
of inlets and cleanouts for maintenance.
(h)
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 to its outfall.
(i)
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.,
and the rules and regulations promulgated thereunder at 25 Pa. Code
§§ 105.441 through 105.449).
(j)
The use of storm sewers is permitted in the MS4 District, but
not recommended to be utilized in the CS4 District unless no other
alternative is practical and feasible as determined by the City Engineer
and the WCD. Refer to Appendix A.[4]
[4]
Editor's Note: Said appendix is included as an attachment to this chapter.
D.
Criteria for riparian buffers.
(1)
If a riparian buffer is required by PA DEP as part of an NPDES permit,
then DEP regulations will govern.
(2)
If a riparian buffer is used to meet stormwater management requirements
and/or MS4 pollutant load reduction credits it shall meet the following
requirements:
(a)
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.
(b)
Except as required by 25 Pa. Code Chapter 102, the riparian
buffer easement shall be 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.
(c)
Minimum management requirements for riparian buffers:
[1]
Existing native vegetation shall be protected and maintained
within the riparian buffer easement.
[2]
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.
[3]
There shall be no earth disturbance beyond which is necessary
to establish or maintain a planted buffer.
(3)
The riparian buffer easement shall be enforceable by the municipality
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 required by zoning, unless otherwise specified in the municipal
Zoning Ordinance.
(4)
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.
(5)
Stormwater drainage pipes and all other linear utility lines as approved
by the City 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.
(7)
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.
E.
Criteria for stream restoration project. A stream restoration project
may be eligible for stormwater management and/or MS4 load reduction
credits if it meets qualifying criteria set by the City and as follows:
(1)
Existing conditions, such as channel or streambank 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, streambanks
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 equaling 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.
A.
No regulated development activities within the City of Monessen shall
commence until approval by the City of Monessen and the WCD of an
erosion and sediment control plan for construction activities.
B.
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.
C.
In addition, under 25 Pa. Code Chapter 92 a DEP NPDES construction
activities permit is required for regulated development activities.
D.
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 City prior to the start of the regulated
development activity. The issuance of an NPDES construction permit
[or permit coverage under the Statewide General Permit (PAG-2)] may
satisfy the requirements under subsection 1[1] upon review and approval by the City.
[1]
Editor's Note: So in original.
E.
A copy of the erosion and sediment control plan and any permit required
by DEP or the City shall be available at the project site at all times.
A.
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 City approval.
B.
Evidence of any necessary Chapter 105 permit from PA DEP/WCD shall
be provided to the City.
C.
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 flood plains.
D.
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 via a hydrologic
and hydraulics analyses, 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 City Council of the City of Monessen.
