A.
For all regulated activities, unless specifically exempted in § 388-12:
(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.[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 (April 15, 2000), as amended and updated.
[1]
Editor's Note: See 35 P.S. § 691.1 et seq.
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, conform
to the state water quality requirements, meet all requirements under
the Storm Water Management Act[2] and any more stringent requirements as determined by the
municipality.
[2]
Editor's Note: See 32 P.S. § 680.1 et seq.
D.
The municipality may, after consultation with PADEP and the Conservation
District, 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. Also, maintenance,
including mowing of vegetation within the easement may be required,
except as approved by the appropriate governing authority.
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.
K.
Design storm volumes and precipitation intensities to be used in
the analysis of discharge or runoff shall be obtained from either
of the following sources:
(1)
The Precipitation-Frequency Atlas of the United States, Atlas 14,
Volume 2, Version 3.0, U.S. Department of Commerce, National Oceanic
and Atmospheric Administration (NOAA), National Weather Service, Hydrometeorological
Design Studies Center, Silver Spring, Maryland. NOAA's Atlas
14 can be accessed at: http://hdsc.nws.noaa.gov/hdsc/pfds/.
L.
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.
M.
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.
N.
The design of facilities over karst shall include an evaluation and
implementation of measures to minimize adverse effects.
O.
Roof drains should not be connected to streets, sanitary or storm
sewers, or roadside ditches.
P.
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.
Q.
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 utilize the following BMPs 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's proposed development/additional impervious area
may not adversely impact the following:
D.
An applicant proposing regulated activities, after demonstrating compliance with § 388-12A, B and C, may be exempted from various requirements of this chapter according to the following table:[1]
|
New Impervious Area1,2
(square footage)
|
Applicant Must Provide
|
|---|---|
|
0 to 1,000
|
—
|
|
1,000 to 2,500
|
Documentation of impervious area3
|
|
2,500 to 5,000
|
Volume Controls Small Project SWM Application3
|
|
> 5,000
|
Rate controls, volume controls and SWM site plan
|
|
NOTES:
| |
|---|---|
|
1
|
New impervious area since the date of adoption of this chapter.
|
|
2
|
Gravel in existing condition shall be considered pervious and
gravel in proposed condition shall be considered impervious.
|
|
3
|
The Small Project Stormwater Management Application included
in Appendix E may be used for projects under 5,000 square feet of
new impervious surface and single-family home construction. The Small
Project SWM Application allows documentation of new impervious surface,
credits through disconnection of impervious surfaces and tree planting,
and sizing of volume control BMPs that may be required.
|
[1]
Editor's Note: Appendix E, Small Project Stormwater Management Application, which is referenced in the table, is included as an attachment to this chapter.
E.
An applicant proposing regulated activities, after demonstrating compliance with § 388-12A, 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, man-made wetlands, or other BMP) has been designed or modified to address the potential stormwater flooding and volume impacts of the proposed development.
F.
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, in consultation with the PADEP (or delegated authority), determines that meeting the volume control requirements (See § 388-14) is not possible or places an undue hardship on the applicant.
(2)
The alternative controls are documented to be acceptable to PADEP
(or delegated authority), for NPDES requirements pertaining to post-construction
stormwater management requirements.
G.
Agricultural activity is exempt from the rate control and SWM site
plan preparation requirements of this chapter, provided the activities
are performed according to the requirements of 25 Pa. Code Chapter
102.
H.
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.
I.
The municipality may deny or revoke any exemption pursuant to this
section at any time for any project that the municipality believes
may pose a threat to public health, safety, property or the environment.
A.
B.
When the applicant demonstrates to the satisfaction of the governing body of the municipality that a requirement of this chapter causes undue hardship as it applies to a proposed project, and that an alternate design produces equal or better results in meeting the purpose and requirements of this chapter, the governing body of the municipality, after completing a thorough technical review consistent with § 388-13A above, may grant a waiver request.
C.
Applicants shall submit requests for waivers in writing, and these
requests shall be included as part of a permit application submission.
In the request for waiver, the applicant shall state in full the facts
of undue hardship on which the request is based, identify the provision
or provisions of the ordinance that are causing such undue hardship,
and state the minimum waiver or relief that is necessary. The applicant
shall state how the proposal in the applicant's waiver request
provides equal or better results in meeting the purpose and requirements
of this chapter.
D.
The municipality shall keep a written record of all actions on waiver
requests in the project file.
E.
The municipality may charge applicants fees for waiver requests sufficient
to cover all costs incurred by the municipality to process the requests.
F.
In processing waiver requests, the municipality may impose reasonable
conditions that will, in its sole judgment, resolve the undue hardship
while meeting the purpose and requirements of this chapter.
G.
The municipality may grant requests for waivers when the following
findings are made by the municipality, when each is determined solely
by the municipality to be applicable and relevant:
(1)
That the waiver shall result in an equal or better means of complying
with the purpose and requirements of this chapter.
(2)
That the waiver is the minimum necessary to provide relief from undue
hardship.
(3)
That the applicant is not requesting a waiver based solely on cost
considerations.
(4)
That existing down gradient stormwater problems will not be exacerbated
by the proposed waiver request.
(5)
That runoff is not being diverted to a different drainage area in
a manner that may cause hardship to others.
(6)
That increased flooding or ponding on off-site properties or roadways
will not be caused by the waiver request.
(7)
That potential icing conditions will not be caused by the waiver
request.
(8)
That increased or unusual municipal maintenance expenses will not
result from the waiver request.
(9)
That operation and maintenance requirements are not reduced by the
waiver request.
B.
Stormwater runoff volume controls shall be implemented using the
Design Storm Method or the Simplified Method as defined below. For
regulated activity areas equal or less than one acre that do not require
hydrologic routing to design the stormwater facilities, this chapter
establishes no preference for either method; therefore, the applicant
may select either method on the basis of economic considerations,
the intrinsic limitations on applicability of the analytical procedures
associated with each methodology, and other factors.
(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 for
all storms equal to or less than the two-year twenty-four-hour storm.
(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.
(2)
The Simplified Method (CG-2 in the BMP Manual) is independent of
site conditions and should be used if the Design Storm Method is not
followed. This method is not applicable to regulated activities greater
than one acre or for projects that require detailed design of stormwater
storage facilities. For new impervious surfaces:
(a)
Stormwater facilities shall capture at least the first two inches
of runoff from all new impervious surfaces.
(b)
At least the first one inch of runoff from new impervious surfaces
shall be permanently removed from the runoff flow, i.e., it shall
not be released into surface waters of the commonwealth. Removal options
include reuse, evaporation, transpiration, and infiltration.
(c)
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.
(d)
Actual field infiltration tests at the location of the proposed
elevation of the stormwater BMPs are required. Infiltration test shall
be conducted in accordance with the BMP Manual. A minimum forty-hour
notification of the municipality shall be provided to allow witnessing
of the testing.
(3)
In cases where it is not possible or desirable to use infiltration-based best management practices to partially fulfill the requirements in either § 388-14B(1) or (2), the following procedure shall be provided to allow witnessing of the testing:
(a)
At a minimum, the following documentation shall be provided
to justify the decision to reduce the use of infiltration BMPs:
[1]
Description of and justification for field infiltration/permeability
testing with respect to the type of test and test locations.
[2]
An interpretive narrative describing existing site soils and
their structure as these relate to the interaction between soils and
water. In addition to providing soil and soil profile descriptions,
this narrative shall identify depth to seasonal high water tables
and depth to bedrock, and provide a description of all subsurface
elements (fragipans and other restrictive layers, geology, etc.) that
influence the direction and rate of subsurface water movement.
[3]
A qualitative assessment of the site's contribution to
annual aquifer recharge shall be made, along with identification of
any restrictions or limitations associated with the use of engineered
infiltration facilities.
[4]
The provided documentation must be signed and sealed by a professional
engineer or geologist.
[5]
A professional opinion stating that the proposed groundwater
recharge is consistent with natural recharge, is reasonable, and is
consistent with this chapter.
(b)
The following water quality pollutant load reductions will be
required for all disturbed areas within the proposed development:
|
Pollutant Load
|
Units
|
Required Reduction
(%)
|
|---|---|---|
|
Total suspended solids (TSS)
|
Pounds
|
85%
|
|
Total phosphorous (TP)
|
Pounds
|
85%
|
|
Total nitrate (NO3)
|
Pounds
|
50%
|
(c)
The performance criteria for water quality best management practices
shall be determined from the Pennsylvania Stormwater Best Management
Practices Manual, most current version.
C.
The applicable worksheets from the BMP Manual must be used in calculations
to establish volume control.
A.
Lands contained within Erie County that have not had release rates
established under an approved Act 167 Stormwater Management Plan:
(1)
Post-development discharge rates shall not exceed the predevelopment
discharge rates for the one-, two-, ten-, twenty-five-, fifty-, and
one-hundred-year storms.
B.
Lands contained within Erie County that have had release rates established
under an approved Act 167 Stormwater Management Plan:
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 hotspots" are defined as a land use that generates higher
concentrations of hydrocarbons, trace metals, or toxicants than are
found in typical stormwater runoff. As such, they have a high potential
to endanger local water quality, and could potentially threaten groundwater
reservoirs. The municipality 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 NAICS 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)
Applicants for projects involving stormwater hotspots may be required
to prepare and implement a stormwater pollution prevention plan and
file notice of intent as required under the provision of the EPA Industrial
Stormwater NPDES Permit requirements.
(3)
Drainage from stormwater hotspots must use an acceptable pretreatment
BMP prior to volume control and/or rate control BMPs. Acceptable pretreatment
BMPs for these developments include those based on filtering, settling,
or chemical reaction processes such as coagulation.
