A.
For all regulated activities, unless specifically exempted in § 183-12:
(1)
Preparation and implementation of an approved SWM site plan is required.
(2)
No regulated activities shall commence until the municipality issues
written approval of a SWM site plan which demonstrates compliance
with the requirements of this chapter.
(4)
The SWM site plan approved by the municipality shall be on site throughout
the duration of the regulated activities.
B.
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 (including,
but not limited to, Chapter 102 Erosion and Sediment Control) and
the Clean Streams Law. Various BMPs and their design standards are
listed in the Erosion and Sediment Pollution Control Program Manual
(E&S Manual), No. 363-2134-008 (April 15, 2000), as amended and
updated.
C.
For all regulated activities, stormwater BMPs shall be designed,
installed, 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 and the Clean Streams Law.
D.
The municipality may 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.
E.
All regulated activities shall include, to the maximum extent practicable,
measures 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, natural slopes,
existing native vegetation and woodlands.
(b)
Create, maintain or extend riparian buffers and protect existing
forested buffers.
(c)
Provide trees and woodlands adjacent to impervious areas whenever
feasible.
(d)
Minimize the creation of impervious surfaces and the degradation
of waters of the commonwealth and promote groundwater recharge.
(e)
Protect natural systems and processes (drainageways, vegetation,
soils and sensitive areas) and maintain, as much as possible, the
natural hydrologic regime.
(f)
Incorporate natural site elements (wetlands, stream corridors,
mature forests) as design elements.
(g)
Avoid erosive flow conditions in natural flow pathways.
(h)
Minimize soil disturbance and soil compaction.
(i)
Minimize thermal impacts to waters of the commonwealth.
(j)
Disconnect impervious surfaces by directing runoff to pervious
areas wherever possible and decentralize and manage stormwater at
its source.
F.
Impervious areas:
G.
If diffused flow is proposed to be concentrated and discharged onto
adjacent property, the applicant must document that adequate downstream
conveyance facilities exist to safely transport the concentrated discharge,
or otherwise prove that no erosion, sedimentation, flooding or other
harm will result from the concentrated discharge.
H.
Stormwater drainage systems shall be provided in order to permit
unimpeded flow along natural watercourses, except as modified by stormwater
management facilities or open channels consistent with this chapter.
I.
Where watercourses traverse a development site, drainage easements
(with a minimum width of 20 feet and include the one-hundred-year
water surface) shall be provided conforming to the line of such watercourses.
The terms of the easement shall prohibit excavation, the placing of
fill or structures, and any alterations that may adversely affect
the flow of stormwater within any portion of the easement.
J.
When it can be shown that, due to topographic conditions, natural
drainageways on the site cannot adequately provide for drainage, open
channels may be constructed conforming substantially to the line and
grade of such natural drainageways. Work within natural drainageways
shall be subject to approval by PADEP under regulations at 25 Pa.
Code Chapter 105 through the joint permit application process or,
where deemed appropriate by PADEP, through the general permit process.
K.
Any stormwater management facilities or any facilities that constitute
water obstructions (e.g., culverts, bridges, outfalls or stream enclosures,
etc.) that are regulated by this chapter, that will be located in
or adjacent to waters of the commonwealth (including wetlands), shall
be subject to approval by PADEP under regulations at 25 Pa. Code Chapter
105 through the joint permit application process or, where deemed
appropriate by PADEP, the general permit process. When there is a
question whether wetlands may be involved, it is the responsibility
of the applicant or his agent to show that the land in question cannot
be classified as wetlands; otherwise, approval to work in the area
must be obtained from PADEP.
L.
Should any stormwater management facility require a dam safety permit
under PADEP regulations in 25 Pa. Code Chapter 105, the facility shall
be designed in accordance with Chapter 105 and meet the regulations
of Chapter 105 concerning dam safety.
M.
Any stormwater management facilities regulated by this chapter that
will be located on or discharged onto state highway rights-of-ways
shall be subject to approval by the Pennsylvania Department of Transportation
(PennDOT).
N.
Minimization of impervious surfaces and infiltration of runoff through
seepage beds, infiltration trenches, etc., are encouraged, where soil
conditions and geology permit, to reduce the size or eliminate the
need for detention facilities.
O.
Infiltration BMPs should be dispersed throughout the site, made as
shallow as practicable, and located to maximize use of natural on-site
infiltration features while still meeting the other requirements of
this chapter.
P.
The design of facilities over karst shall include an evaluation and
implementation of measures to minimize adverse effects.
Q.
Roof drains shall be connected to storm sewers when possible. If
they cannot be so connected, then the drains shall be directed to
the street, unless doing so would create a dangerous or hazardous
situation. Roof drains may not be connected to sanitary sewers.
R.
Applicants are encouraged to use low-impact development practices
to reduce the costs of complying with the requirements of this chapter
and the state water quality requirements.
S.
When stormwater management facilities are proposed within 1,000 feet
of a downstream municipality, the developer shall notify the downstream
municipality and provide a copy of the SWM plan, if requested, for
review and comment.
B.
The applicant must demonstrate that the following BMPs are being
utilized to the maximum extent practicable to receive consideration
for the exemptions:
(1)
Design around and limit disturbance of floodplains, wetlands, natural
slopes over 15%, existing native vegetation, and other sensitive and
special value features.
(2)
Maintain riparian and forested buffers.
(3)
Limit grading and maintain nonerosive flow conditions in natural
flow paths.
(4)
Maintain existing tree canopies near impervious areas.
(5)
Minimize soil disturbance and reclaim disturbed areas with topsoil
and vegetation.
(6)
Direct runoff to pervious areas.
C.
The applicant must demonstrate that the proposed development/additional
impervious area will not adversely impact the following:
D.
An applicant proposing regulated activities, after demonstrating compliance with § 183-12A, B, and C, may be exempted from various requirements of this chapter according to the following table:
|
New Impervious Area1
(square feet)
|
Applicant Must Provide
| |
|---|---|---|
|
0 to 10,000
|
—
| |
|
10,000 to 40,000
|
Volume controls and SWM site plan
| |
|
More than 40,000
|
Rate controls, volume controls and SWM site plan
|
|
NOTES:
| ||
|---|---|---|
|
1
|
New impervious area since the date of adoption of this chapter.
| |
F.
The municipality can require more information or require mitigation
of certain impacts through installation of stormwater management BMPs
if there is a threat to property, health or safety.
G.
An applicant proposing regulated activities, after demonstrating compliance with § 183-12A, B and C, may be exempted from various requirements of this chapter if documentation can be provided that a downstream man-made water body (i.e., reservoir, lake or man-made wetlands) has been designed or modified to address the potential stormwater flooding impacts of the proposed development.
H.
The purpose of this section is to ensure consistency of stormwater
management planning between local ordinances and NPDES permitting
(when required) and to ensure that the applicant has a single and
clear set of stormwater management standards to which the applicant
is subject. The municipality may accept alternative stormwater management
controls under this section, provided that:
(1)
The municipality determines that meeting the volume control requirements (see § 183-14) is not possible or places an undue hardship on the applicant.
(2)
The alternative controls are documented to be acceptable for NPDES
requirements pertaining to post-construction stormwater management
requirements.
I.
Agricultural activities are exempt from requirements of this chapter,
provided the activities are performed according to the requirements
of 25 Pa. Code Chapter 102.
J.
Forest management and timber operations are exempt from the rate
and volume control requirement and SWM site plan preparation requirement
of this chapter, provided the activities are performed according to
the requirements of 25 Pa. Code Chapter 102. It should be noted that
temporary roadways are not exempt.
A.
The provisions of this chapter are the minimum standards for the
protection of the public welfare.
C.
If an applicant demonstrates to the satisfaction of the governing body of the municipality that any mandatory provision of this chapter is unreasonable or causes unique or undue unreasonableness or hardship as it applies to the proposed project, or that an alternate design may result in a superior result within the context of §§ 183-2 and 183-3 of this chapter, the governing body of the municipality, upon obtaining the comments and recommendations of the Municipal Engineer, may grant a waiver or relief so that substantial justice may be done and the public interest is secured, provided that such waiver will not have the effect of nullifying the intent and purpose of this chapter.
D.
The applicant shall submit all requests for waivers in writing and
shall include such requests as a part of the plan review and approval
process. The applicant shall state in full the facts of unreasonableness
or hardship on which the request is based, the provision or provisions
of the chapter that are involved, and the minimum waiver or relief
that is necessary. The applicant shall state how the requested waiver
and how the applicant's proposal shall result in an equal or
better means of complying with the intent or purpose and general principles
of this chapter.
E.
The municipality shall keep a written record of all actions on waiver
requests.
F.
The municipality may charge a fee for each waiver request, which
shall be used to offset the administrative costs of reviewing the
waiver request. The applicant shall also agree to reimburse the municipality
for reasonable and necessary fees that may be incurred in any review
of a waiver request.
G.
In granting waivers, the municipality may impose reasonable conditions
that will, in its judgment, secure substantially the objectives of
the standards or requirements that are to be modified.
H.
The municipality may grant applications for waivers when the following
findings are made, as relevant:
(1)
That the waiver shall result in an equal or better means of complying
with the intent of this chapter.
(2)
That the waiver is the minimum necessary to provide relief.
(3)
That the applicant is not requesting a waiver based on cost considerations.
(4)
That existing downgradient stormwater problems will not be exacerbated.
(5)
That increased flooding or ponding on off-site properties or roadways
will not occur.
(6)
That potential icing conditions will not occur.
(7)
That increase of peak flow or volume from the site will not occur.
(8)
That erosive conditions due to increased peak flows or volume will
not occur.
(9)
That adverse impact to water quality will not result.
(10)
That increased one-hundred-year floodplain levels will not result.
(11)
That increased or unusual municipal maintenance expenses will
not result from the waiver.
(12)
That the amount of stormwater generated has been minimized to
the greatest extent allowed.
(13)
That infiltration of runoff throughout the proposed site has
been provided where practicable and predevelopment groundwater recharge
protected.
(14)
That peak flow attenuation of runoff has been provided.
(15)
That long-term operation and maintenance activities are established.
(16)
That the receiving streams and/or water bodies will not be adversely
impacted in flood-carrying capacity, aquatic habitat, channel stability
and erosion and sedimentation.
(17)
That post-development runoff does not exceed predevelopment
runoff.
A.
The lo- impact development practices provided in the BMP Manual shall
be utilized for all regulated activities to the maximum extent practicable.
B.
Stormwater runoff volume controls shall be implemented using the
Design Storm Method as defined below.
(1)
The Design Storm Method (CG-1 in the BMP Manual) is applicable to
any sized regulated activity. This method requires detailed modeling
based on site conditions.
(a)
Do not increase the post-development total runoff volume when
compared to the predevelopment total runoff volume for the two-year/twenty-four-hour
storm event.
(b)
For hydrologic modeling purposes:
[1]
Existing nonforested pervious areas must be considered meadow
(good condition) for predevelopment hydrologic calculations.
[2]
Twenty percent of existing impervious area, when present within
the proposed project site, shall be considered meadow (good condition)
for predevelopment hydrologic calculations for redevelopment.
C.
The applicable worksheets from the BMP Manual must be used in calculations
to establish volume control.
A.
Post-development discharge rates shall not exceed the predevelopment
discharge rates for the one-, two-, ten-, twenty-five-, fifty-, and
one-hundred-year storms.
A.
Sensitive areas and water quality sensitive developments, as defined
below, which require special consideration with regard to stormwater
management.
(1)
Sensitive areas are defined as those areas that, if developed, have
the potential to endanger a water supply. These areas consist of the
delineated one-year zone of contribution and direct upslope areas
tributary to the water supply wells. Municipalities may update the
sensitive area boundaries based on new research or studies as required.
(2)
Stormwater hot spots are defined as land development projects that
have a high potential to endanger local water quality and could potentially
threaten groundwater reservoirs. The Municipal Engineer will determine
what constitutes these classifications on a case-by-case basis. The
PADEP wellhead protection contaminant source list shall be used as
a guide in these determinations. Industrial manufacturing site and
hazardous material storage areas must provide NPDES SIC codes.
B.
Performance standards.
(1)
The location of the boundaries of sensitive areas is set by drainage
areas tributary to any public water supply. The exact location of
these boundaries as they apply to a given development site shall be
determined using mapping at a scale which accurately defines the limits
of the sensitive area. If the project site is within the sensitive
area (in whole or in part), two-foot contour interval mapping shall
be provided to define the limits of the sensitive area. If the project
site is adjacent to but within 500 linear feet of a defined sensitive
area, a five-foot contour interval map defining the limits of the
sensitive area shall be included in the stormwater management plan
to document the site's location relative to the sensitive area.
(2)
Stormwater hot spots may be required to prepare and implement a stormwater
pollution prevention plan and file notice of intent as required under
the provision of the EPA industrial stormwater NPDES permit requirements.
(3)
Stormwater hot spots must use an acceptable pretreatment BMP prior
to volume control and/or rate control BMPs. Acceptable pretreatment
BMPs for these developments include those based on filtering, settling
or chemical reaction processes such as coagulation.
