A.
For all regulated activities, unless specifically exempted in § 26-122:
(1)
Preparation and implementation of an approved SWM site plan is required.
Unless specifically and individually granted as an exception to this
Part 1, no distinction shall be made between types of land development
(minor or major) required to meet the standards of this Part 1.
(2)
No regulated activities shall commence until the Township issues
written approval of a SWM site plan, which demonstrates compliance
with the requirements of this Part 1.
(4)
The SWM site plan approved by the Township 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 Part 1 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).
[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 Part 1 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
Township.
[2]
Editor's Note: See 32 P.S. § 680.1 et seq.
D.
The Township may, after consultation with PADEP and the Conservation
District, approve measures for meeting the state water quality requirements
other than those in this Part 1, 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 Part 1 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.
(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 developments taking place in stages, the entire development plan
must be used in determining conformance with this Part 1.
(3)
For projects that add impervious area to a parcel, the total impervious
area on the parcel is subject to the requirements of this Part 1.
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 Part 1.
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. 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 Part 1, 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 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 Part 1 that
will be located on, or discharged onto, state highway rights-of-way
shall be subject to approval by 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 Part 1.
P.
The design of facilities over karst shall include an evaluation and
implementation of measures to minimize adverse effects.
Q.
On residential lots greater than 1/2 acre in size, roof drains shall
not be connected to streets, sanitary or storm sewers, or roadside
ditches in order to promote overland flow and infiltration/percolation
of stormwater where it is advantageous to do so. On residential lots
smaller than 1/2 acre in size, all roof drains shall be connected
to a centralized stormwater facility when provided within a development.
[Amended 1-17-2019 by Ord. No. 19-04]
R.
Applicants are encouraged to use low-impact development practices
to reduce the costs of complying with the requirements of this Part
1 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 may be eligible for exemption
from rate control, volume control, or stormwater management site plan
requirements in this Part 1 according to the following table:
|
Table 26-122.1
Exemptions and Submission Requirements
| ||
|---|---|---|
|
New Impervious Area1, 2
(square footage)
|
Applicant Must Provide
| |
|
0 < 2,500
|
No submission is required
| |
|
2,500 < 5,000
|
Documentation of new impervious surfaces3
| |
|
5,000 and greater
|
Rate controls, volume controls and SWM site plan
| |
|
NOTES:
| ||
|---|---|---|
|
1
|
New impervious area since the date of adoption of this Part
1.
| |
|
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, in such
form as may be prescribed from time to time by the Township, shall
be used to document new impervious surfaces.
| |
E.
Single-family residential activities are exempt from these requirements,
provided the construction:
F.
An applicant proposing regulated activities, after demonstrating compliance with Subsections A, B and C of this section, may be exempted from various requirements of this Part 1 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.
G.
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 Township may accept alternative stormwater management
controls under this section, provided that:
(1)
The Township, in consultation with the PADEP (or delegated authority), determines that meeting the volume control requirements (see § 26-124) 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.
H.
Agricultural activities are exempt from the rate control and SWM site plan preparation requirements of this Part 1, provided the activities are performed according to the requirements of 25 Pa. Code Chapter 102.
I.
Forest management and timber operations are exempt from the rate and volume control requirements and SWM site plan preparation requirements of this Part 1, 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.
J.
The Township may deny or revoke any exemption pursuant to this section
at any time for any project that the Township believes may pose a
threat to public health, safety, property or the environment.
K.
A small project stormwater management application, in such form as
may be prescribed from time to time by the Township, shall be used
to document new impervious surfaces and for determination of whether
such regulated activities meet the stormwater management standards
listed in this Part 1.
A.
The provisions of this Part 1 are the minimum standards for the protection
of the public welfare.
B.
C.
If an applicant demonstrates to the satisfaction of the Board of Supervisors that any mandatory provision of this Part 1 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 §§ 26-102 and 26-103 of this Part 1, the Board of Supervisors, upon obtaining the comments and recommendations of the Township 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 Part 1.
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 ordinance 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 Part 1.
E.
The Township shall keep a written record of all actions on waiver
requests.
F.
The Township may charge a fee for each waiver request, which shall be established from time to time by resolution of the Board of Supervisors pursuant to § 26-196. The applicant shall reimburse the Township for all fees and expenses that may be incurred by the Township in any review of a waiver request pursuant to § 26-197.
G.
In granting waivers, the Township may impose reasonable conditions
as will, in its judgment, secure substantially the objectives of the
standards or requirements that are to be modified.
H.
The Township 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 Part 1.
(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 runoff is not being diverted to a different drainage area.
(6)
That increased flooding or ponding on off-site properties or roadways
will not occur.
(7)
That potential icing conditions will not occur.
(8)
That increase of peak flow or volume from the site will not occur.
(9)
That erosive conditions due to increased peak flows or volume will
not occur.
(10)
That adverse impact to water quality will not result.
(11)
That increased one-hundred-year floodplain levels will not result.
(12)
That increased or unusual municipal maintenance expenses will
not result from the waiver.
(13)
That the amount of stormwater generated has been minimized to
the greatest extent allowed.
(14)
That infiltration of runoff throughout the proposed site has
been provided where practicable and predevelopment groundwater recharge
protected.
(15)
That peak flow attenuation of runoff has been provided.
(16)
That long-term operation and maintenance activities are established.
(17)
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.
A.
The low-impact development practices provided in the BMP Manual and in Appendix 26-1-A of this Part 1[1] shall be utilized for all regulated activities to the
maximum extent practicable.
[1]
Editor's Note: Appendix 26-1-A is included as an attachment to this chapter.
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 Part
1 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 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.
(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 tests
shall be conducted in accordance with the BMP Manual. Notification
of the Township 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 Subsection B(1) or (2), the following procedure shall be used:
(a)
At a minimum, the following documentation shall be provided
to justify the decision to not use 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 occurring on the site. 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.
(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 BMPs shall be determined
from the BMP Manual.
C.
The applicable worksheets from the BMP Manual must be used in calculations
to establish volume control.
A.
Lands contained within Butler 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-year, two-year, ten-year, twenty-five-year,
fifty-year, and one-hundred-year storms.
B.
Lands contained within Butler County that have had release rates
established under an approved Act 167 stormwater management plan.
(1)
The post-development peak discharge rates shall be in accordance
with the approved release rate map for the following watersheds (see
Appendix 26-1-C for Release Rate Map[1]):
(a)
Connoquenessing Creek Watershed.
[1]
Editor's Note: Appendix 26-1-C is included as an attachment to this chapter.
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. The Township may update
the sensitive area boundaries based on new research or studies as
required.
(2)
"Stormwater hotspots" are defined as a land development project that
has a high potential to endanger local water quality and could potentially
threaten groundwater reservoirs. The Township 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 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)
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.
