A.
The following requirements shall apply to all regulated activities, unless preparation of an SWM site plan is specifically exempted in § 177-12:
(1)
Preparation and implementation of an approved SWM site plan is required.
(2)
No regulated activities shall commence until the Borough issues written
approval of an SWM site plan, which demonstrates compliance with the
requirements of this chapter.
(3)
The Borough shall be notified of construction operations prior to
commencement so that an inspection can be completed.
(4)
After the installation of stormwater management facility, the overseeing
professional engineer (design engineer) should submit a letter indicating
that the facility was installed per the approved plan.
B.
SWM site plans approved by the Borough, in accordance with § 177-22, shall be on site throughout the duration of the regulated activity.
C.
These standards apply to the landowner and any person engaged in
regulated activities.
D.
Stormwater drainage systems shall be provided in order to permit
unimpeded flow along natural watercourses, except as modified by SWM
BMPs or open channels consistent with this chapter.
E.
If diffused flow is proposed to be concentrated and discharged onto
adjacent property with permission from the receiving property owner,
the developer must document that adequate downstream conveyance facilities
exist to safely transport the concentrated discharge, or otherwise
prove that no erosion, sedimentation, flooding, or other harm will
result from the concentrated discharge and downstream easements shall
be established to provide drainage paths for concentrated discharge.
Maximum use shall be made of the existing on-site natural and man-made
stormwater management facilities.
F.
A concentrated discharge of stormwater to an adjacent property shall
be within an existing watercourse or otherwise an easement shall be
required. Pipe outlets shall also be provided with erosion-resistant
material or energy dissipaters to calm the anticipated velocity and
discharge of stormwater.
G.
Discharge points from any facility must be 15 feet from any property
line with adequate BMPs to ensure no channelizing of flows onto neighboring
property.
H.
For all regulated earth disturbance activities, erosion and sediment
control BMPs shall be designed, implemented, operated, and maintained
during the regulated earth disturbance activities (e.g., during construction)
to meet the purposes and requirements of this chapter and to meet
all requirements under Title 25 of the Pennsylvania Code and the Clean
Streams Law.[1] Various BMPs and their design standards are listed in
the Erosion and Sediment Pollution Control Program Manual (E&S
Manual), No. 363-2134-008, as amended and updated.
[1]
Editor's Note: See 35 P.S. § 691.1 et seq.
I.
Impervious areas shall be subject to the following standards:
(1)
The measurement of impervious areas shall include all of the impervious
areas in the total proposed development even if development is to
take place in stages.
(2)
For development taking place in stages, the entire development plan
must be used in determining conformance with this chapter.
(3)
For projects that add impervious area to a parcel, the total impervious area on the parcel is subject to the requirements of this chapter, except that the volume controls in § 177-14 and the peak rate controls of § 177-15 do not need to be retrofitted to existing impervious areas that are not being altered by the proposed regulated activity.
(4)
Stormwater flows onto adjacent or downstream property shall not be
created, increased, decreased, relocated, impeded, or otherwise altered
without written notification of the affected property owner(s). Notification
shall include a description of the proposed development and the stormwater
flows that are being created, increased, decreased, relocated, impeded,
or otherwise altered. Adjacent property shall, at a minimum, include
any property having a shared boundary with the subject property of
the SWM site plan; however, if in the judgement of the designated
plan reviewer additional properties are being affected, additional
notifications may be required. Proof of notification shall be included
as part of the SWM plan submission to the Borough. Such stormwater
flows shall be subject to the requirements of this chapter.
J.
All regulated activities shall include such measures as necessary
to:
(1)
Protect health, safety, and property.
(2)
Meet the water quality goals of this chapter by implementing measures
to:
(a)
Minimize disturbance to floodplains, wetlands, and wooded areas.
(b)
Maintain or extend riparian buffers.
(c)
Avoid erosive flow conditions in natural flow pathways.
(d)
Minimize thermal impacts to waters of this commonwealth.
(e)
Disconnect impervious surfaces by directing runoff to pervious
areas, wherever possible.
(3)
Incorporate methods described in the Pennsylvania Stormwater Best
Management Practices Manual (BMP Manual). If methods other than green
infrastructure and LID methods are proposed to achieve the volume
and rate controls required under this chapter, the SWM site plan must
include a detailed justification, acceptable to the designated plan
reviewer, demonstrating that the use of LID and green infrastructure
is not practicable.
K.
Infiltration BMPs should be dispersed throughout the project site
at strategic locations, made as shallow as practicable, and located
to maximize use of natural on-site infiltration features while still
meeting the other requirements of this chapter.
L.
Normally dry, open top storage facilities should completely drain
both the volume control and rate control capacities over a period
of time not less than 24 and not more than 72 hours from the end of
the design storm.
M.
The design storm precipitation depths to be used in the analysis
of peak rates of discharge shall be as obtained in PennDOT's
Drainage Manual, Publication 584, Appendix 7A; or obtained from the
latest version of the Precipitation-Frequency Atlas of the United
States, National Oceanic and Atmospheric Administration (NOAA), National
Weather Service, Hydrometeorological Design Studies Center, Silver
Spring, Maryland.
N.
For all regulated activities, SWM BMPs shall be designed, implemented,
operated, and maintained to meet the purposes and requirements of
this chapter and to meet all requirements under Title 25 of the Pennsylvania
Code, the Clean Streams Law[2] and the Storm Water Management Act.
[2]
Editor's Note: See 35 P.S. § 691.1 et seq.
O.
Various BMPs and their design standards are listed in the BMP Manual.
P.
The Borough may, after consultation with DEP, approve measures for
meeting the state water quality requirements other than those in this
chapter, provided that they meet the minimum requirements of, and
do not conflict with, state law, including, but not limited to, the
Clean Streams Law.
Q.
Stormwater management facilities which involve a state highway shall
be subject to the approval of PennDOT.
R.
Stormwater management facilities which involve a county highway or
a county facility shall be subject to the approval of Allegheny County.
S.
Minimization of impervious surfaces and maximization of infiltration
of runoff through seepage beds, infiltration trenches, etc., are encouraged,
where soil conditions permit, to reduce the size or eliminate the
need for detention facilities.
T.
Where a development site is traversed by watercourses other than
permanent streams, drainage easements shall be provided conforming
to the line of such watercourses. The terms of the easement shall
prohibit excavation, the placing of fill or structures, and any alterations
that may adversely affect the flow of stormwater within any portion
of the easement. Also, maintenance, including mowing of vegetation
within the easement, shall be required, except as approved by the
appropriate governing authority.
U.
The Pa. Code, Title 25, Chapter 105, Rules and Regulations, apply
to the construction, modification, operation or maintenance of both
existing and proposed water obstructions and encroachments throughout
the watershed, including work in wetlands. Inquiries on permit requirements
or other concerns shall be addressed to the DEP, Bureau of Waterways
Engineering and Wetlands, in Harrisburg.
V.
When it can be shown that, due to topographic conditions, natural
drainageways on the site cannot adequately provide for drainage, open
channels may be constructed conforming substantially to the line and
grade of such natural drainageways. Work within natural drainageways
shall be subject to approval by DEP through the joint permit application
process or, where deemed appropriate by DEP, through the general permit
process.
W.
Stormwater resulting from regulated activities shall not be discharged
into sinkholes.
X.
To the maximum extent practicable, incorporate the techniques for
low-impact development practices described in the BMP Manual.
A.
Regulated activities that result in cumulative earth disturbances less than one acre, as well as proposed impervious area less than 4,000 square feet, are exempt from the requirements in § 177-17, except as provided below.
B.
Earth disturbances between 0.25 acre (10,890 square feet) and one acre of earth disturbance, as well as proposed impervious area between 750 square feet and 4,000 square feet, must submit a SWM site plan to the Borough which shall consist of the items and related supportive material needed to determine compliance with § 177-13.
C.
Agricultural activity is exempt from the SWM site plan preparation requirements of this chapter, provided the activities are performed according to the requirements of 25 Pa. Code Chapter 102.
D.
Forest management and timber operations are exempt from the SWM site plan preparation requirements of this chapter, provided the activities are performed according to the requirements of 25 Pa. Code Chapter 102.
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. Exemptions from any provisions of this chapter shall not relieve the applicant from the requirements in § 177-11C through § 177-13N.
F.
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 and safety or the environment.
G.
Voluntary green stormwater infrastructure (GSI) retrofit projects
that are solely intended to better manage runoff from existing development
and are not part of new development or redevelopment are exempt from
the stormwater management provisions of this chapter. This does not
exempt such projects from any other municipal, state, or federal regulation.
A.
Projects proposing less than 750 square feet of additional impervious
area are exempt from any stormwater management plan.
B.
Projects proposing greater than 750 square feet but less than 4,000
square feet of additional impervious area must submit the following
stormwater management information to the Borough:
(1)
Brief description of the proposed project, including proposed stormwater
management facilities, including types of materials to be used, and
an approximation of the square footage of additional impervious areas.
(2)
Sketch plan showing location of proposed improvements and stormwater
management facilities in relation to the property lines and existing
structures, septic systems and/or water wells, and roadways.
(3)
Supporting runoff volume calculations and stormwater BMP sizing calculations,
as requested.
C.
Capture and detention can be accomplished by a variety of methods,
including, but not limited to:
D.
In all cases, the detention method shall be designed to drain all
accumulated runoff not less than 24 hours and not more than 72 hours
after the end of the storm event. Appropriate soil percolation conditions
must be available for stone sumps and rain gardens and must be demonstrated
by percolation tests.
E.
A maintenance agreement must be signed by the property owner to ensure
the proper continual inspection and maintenance of the capture and
detention method.
F.
The property owner shall submit the following stormwater management
information for review by the Borough staff:
(1)
A written description of the proposed project, including the dimensions
of all proposed impervious surfaces.
(2)
A scale drawing showing existing and proposed features of the property.
(3)
A written description of the proposed stormwater management methods.
(4)
Dimensioned drawings of the proposed stormwater management methods
and their locations.
(5)
A list of proposed impervious surfaces and their square footage.
(6)
Supporting documentation, such as assumptions, calculations, rain
barrel size, stone size, percolation tests, etc.
(7)
Draft operation and maintenance agreement.
(8)
Construction of the proposed improvements shall not begin prior to
receiving approval of the stormwater management plan from the Borough.
A.
The green infrastructure and low-impact development practices provided in the BMP Manual shall be utilized for all regulated activities wherever possible. Water volume controls shall be implemented using the Design Storm Method or the Simplified Method, or alternative design criteria as allowed by Pa. Code Title 25, Chapter 102.
B.
The Design Storm Method (CG-1 in the BMP Manual) is applicable as
a method to any size of regulated activity. This method requires detailed
modeling based on site conditions. The following shall be incorporated
into the CG-1 method:
(1)
Do not increase the post-development total runoff volume for all
storms equal to or less than the two-year twenty-four-hour duration
precipitation.
(2)
At least the first one inch of runoff from the net increase in impervious
surfaces shall be permanently removed from the runoff flow, i.e.,
it shall not be released into the surface waters of this commonwealth.
Removal options include reuse, evaporation, transpiration, and infiltration.
If the developer provides justification that the listed removal options
are not feasible, and the designated plan reviewer agrees, runoff
shall be detained in a facility designed for a twenty-four- to seventy-two-hour
dewatering time in an area with a dedicated stormwater system and
shall be detained in a facility designed for a seventy-two-hour dewatering
time in an area contributory to a combined sewer system before discharge
to local stormwater systems or the environment.
C.
The Simplified Method (CG-2 in the BMP Manual) provided below is
independent of site conditions and should be used if the Design Storm
Method is not followed. This method is not applicable to regulated
activities greater than one acre or for projects that require design
of stormwater storage facilities. For new impervious surfaces:
(1)
Stormwater facilities shall capture at least the first two inches
of runoff from the net increase in impervious surfaces.
(2)
At least the first one inch of runoff from the net increase in impervious
surfaces shall be permanently removed from the runoff flow, i.e.,
it shall not be released into the surface waters of this commonwealth.
Removal options include reuse, evaporation, transpiration, and infiltration.
If the developer provides justification that the listed removal options
are not feasible, and the designated plan reviewer agrees, runoff
shall be detained in a facility designed for a twenty-four-hour dewatering
time in an area with a dedicated stormwater system and shall be detained
in a facility designed for a seventy-two-hour dewatering time in an
area contributory to a combined sewer system before discharge to local
stormwater systems or the environment.
(3)
Wherever possible, infiltration facilities should be designed to
accommodate infiltration of the entire permanently removed runoff;
however, in all cases at least the first 0.5 inch of the permanently
removed runoff should be infiltrated.
A.
For areas not covered by a release rate map from an approved Act
167 Stormwater Management Plan, post-development discharge rates shall
not exceed the predevelopment discharge rates for the one-, two-,
five-, ten-, twenty-five-, fifty-, and 100-year, twenty-four-hour
storm events. This is the equivalent to a 100% release rate area when
compared to those rates shown in the maps contained in Appendix A.
This predevelopment to post-development control is not to be misconstrued
as the same as the "conditional direct discharge" areas on the release
rate maps. If it is shown that the peak rates of discharge indicated
by the post-development analysis are less than or equal to the peak
rates of discharge indicated by the predevelopment analysis for one-,
two-, five-, ten-, twenty-five-, fifty-, and 100-year, twenty-four-hour
storms, then the requirements of this section have been met. Otherwise,
the applicant shall provide additional controls as necessary to satisfy
the peak rate of discharge requirement. Peak flows should be computed
using the methods included in the chapter titled "Stormwater Calculations
and Methodology" of the PADEP Stormwater Management BMP Manual.
B.
For areas covered by a release rate map from an approved Act 167
Stormwater Management Plan, for the one-, two-, five-, ten-, twenty-five-,
fifty-, and 100-year, twenty-four-hour storm events, the post-development
peak discharge rates will follow the applicable approved release rate
maps. These maps are contained in Appendix A of this chapter.[1] For any areas not shown on the release rate maps, the
post-development discharge rates shall not exceed the predevelopment
discharge rates for the specified design events. Peak flows should
be computed using the methods included in Chapter 8 of the PADEP Stormwater
Management BMP Manual.
[1]
Editor's Note: Said maps are on file in the Borough offices.
A.
In order to protect and improve water quality, a riparian buffer
easement shall be created and recorded as part of any subdivision
or land development that encompasses a riparian buffer. The intent
of this chapter in establishing a riparian buffer is to protect and
improve stream water quality. The riparian buffer is intended to slow
overland flow to the stream through the presence of native grasses,
trees and shrubs, allowing infiltration/groundwater recharge; causing
deposition of sediment, nutrients, pesticides, and other pollutants
in the buffer rather than in the stream; and reducing erosion by providing
stream bank stabilization. The trees provide shade for streams, which
keeps waters cooler and reduces evaporation.
B.
Except as required by Pa. Code Title 25, Chapter 102, the riparian buffer easement shall be required for all streams with a contributing watershed area of greater than 10 acres. The riparian buffer easement shall be measured to be a minimum of 35 feet from the top of the streambank on each side.
C.
Riparian buffers shall be subject to the following minimum management
requirements.
(1)
No use or construction within the riparian buffer shall be permitted that is inconsistent with the intent of the riparian buffer as described in § 177-16A.
(2)
Existing native vegetation shall be protected and maintained within
the riparian buffer easement.
(3)
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.
D.
The riparian buffer easement shall be enforceable by the Borough
and shall be recorded with the County of Allegheny 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.
E.
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.
F.
Stormwater drainage pipes shall be permitted within the riparian
buffer easement, but they shall cross the easement in the shortest
practical distance. Other structural stormwater management facilities
are not permitted within the riparian buffer easement.
G.
The following conditions shall apply when public and/or private recreation
trails are permitted by the Borough within riparian buffers:
H.
Septic drainfields 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.
I.
Underground utilities shall be permitted within the riparian buffer
easement; however, work shall be performed to minimize disturbance
area and removal of trees. Restoration within the riparian buffer
easement shall be with native species of trees, grasses, and other
plantings. One tree shall be planted for each tree removed and the
restoration shall be designed by a Registered Professional with the
requisite experience. Aboveground utilities shall only be permitted
to cross the easement perpendicular to the easement or in the shortest
practical distance. Existing utilities may remain and be maintained
as required.
J.
Public streets and private streets shall be permitted within the
riparian buffer easement; however, work shall be performed to minimize
disturbance area and removal of trees. The disturbed area shall require
an offset riparian buffer at a 1:1 ratio with native species of trees,
grasses, and other plantings. One tree shall be planted for each tree
removed, and the restoration shall be designed by a registered professional
with the requisite experience. Public streets and private streets
shall only be permitted to cross the easement perpendicular to the
easement or in the shortest practical distance.
