[Ord. No. 383, 8/27/2019]
1.
For all regulated activities, unless specifically exempted in § 26-302:
A.
Preparation and implementation of an approved SWM site plan is required.
B.
No regulated activities shall commence until the Township issues
written approval of a SWM site plan, which demonstrates compliance
with the requirements of this chapter.
D.
The SWM site plan approved and signed by the Township shall be on-site
throughout the duration of the regulated activities.
2.
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 Act 167 and the regulations promulgated thereunder
(including, but not limited to, Chapter Title 25 of the Pennsylvania
Code, Chapter 102, Erosion and Sediment Control). Various BMPs and
their design standards are listed in the Erosion and Sediment Pollution
Control Program Manual (E&S Manual), No. 363-2134-008 (March 31,
2012), as amended and updated.
3.
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
Act 167 and the regulations promulgated thereunder, conform to the
state water quality requirements, meet all requirements under the
Storm Water Management Act and any more stringent requirements as
determined by the Township.
4.
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 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.
5.
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 judgment of the designated plan
reviewer additional properties are being affected, additional notifications
may be required. Proof of notification (signed postal receipt, for
example) shall be included as part of the SWM plan submission to the
municipality. Such stormwater flows shall be subject to the requirements
of this chapter.
6.
All regulated activities shall include, to the maximum extent practicable,
measures to:
A.
Protect health, safety, and property.
B.
Meet the requirements of this chapter by implementing measures to:
(1)
Minimize disturbance to floodplains, wetlands, natural slopes,
existing native vegetation and woodlands.
(2)
Encourage the creation, maintenance and extension of riparian
buffers and the protection existing forested buffers.
(3)
Provide trees and woodlands adjacent to impervious areas whenever
feasible.
(4)
Minimize the creation of impervious surfaces and the degradation
of waters of the commonwealth and promote groundwater recharge.
(5)
Protect natural systems and processes (drainageways, vegetation,
soils, and sensitive areas) and maintain, as much as possible, the
natural hydrologic regime.
(6)
Incorporate natural site elements (wetlands, stream corridors,
mature forests) as design elements.
(7)
Avoid erosive flow conditions in natural flow pathways.
(8)
Minimize soil disturbance and soil compaction.
(9)
Minimize thermal impacts to waters of the commonwealth.
(10)
Disconnect impervious surfaces by directing runoff to pervious
areas, wherever possible and decentralize and manage stormwater at
its source.
7.
Impervious Areas:
A.
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.
B.
For developments taking place in stages, the entire development plan
must be used in determining conformance with this chapter.
C.
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 § 26-303 and the peak rate controls of § 26-304 do not need to be retrofitted to existing impervious areas that are not being altered by the proposed regulated activity.
8.
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.
9.
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.
10.
Stormwater drainage systems shall not be permitted to have open discharge
points within 25 feet of a public right-of-way. The discharge must
be piped and connected to an existing public storm sewer system or
conveyed to a stable discharge location such as a stream, and all
required permits must be obtained and provided to the Township.
11.
Stormwater drainage systems that discharge within 25 feet of adjacent
downstream property lines may be subject to modification as required
by the Township, should it be determined that there is substantial
risk of damage to the downstream property.
12.
Where watercourses traverse a development site, drainage areas with
a minimum width of 20 feet and including the 100-year water surface
shall be provided conforming to the line of such watercourses. Excavation,
the placing of fill or structures, and any alterations that may adversely
affect the flow of stormwater within any portion of the drainage area
shall be prohibited. Also, maintenance, including mowing of vegetation
within the drainage area, may be required, except as approved by the
appropriate governing authority.
13.
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 drainage ways
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.
Open channel location, lining, and discharge orientation may be subject
to modification as required by the Township.
14.
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.
15.
Should any stormwater management facility require a dam safety permit
under PADEP Chapter 105, the facility shall be designed in accordance
with Chapter 105 and meet the regulations of Chapter 105 concerning
dam safety.
16.
Any stormwater management facilities regulated by this chapter that
will be located on or discharged onto state highway rights-of-way
shall be subject to approval by the Pennsylvania Department of Transportation
(PennDOT).
17.
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.
18.
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. No portion of an infiltration BMP constructed slope
shall be within 30 feet of adjacent downstream properties or public
rights-of-way. The Township may require that the outfall pipe be connected
to an existing storm sewer system or conveyed through a property to
a stable discharge location to prevent runoff damage to the downstream
property. Additional provisions to ensure safety of downstream features
may be required by the Township.
19.
No portion of a stormwater management detention/retention BMP constructed
slope shall be within 15 feet of adjacent downstream properties or
public rights-of-way. The Township may require that the outfall pipe
be connected to an existing storm sewer system or conveyed through
a property to a stable discharge location to prevent runoff damage
to the downstream property. Additional provisions to ensure safety
of downstream features may be required by the Township.
20.
All roof drains shall be connected to a storm sewer system to prevent
overland flow. All roof drains must have watertight connections to
prevent exfiltration.
21.
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.
22.
Applicants are encouraged to utilize underground stormwater management
facilities where possible, instead of surface water impoundments.
23.
When stormwater management facilities are proposed within 1,000 feet
of a downstream Township, the developer shall notify the downstream
Township and provide a copy of the SWM plan, if requested, for review
and comment.
[Ord. No. 383, 8/27/2019]
2.
The applicant must demonstrate that the following BMPs are being
utilized to the maximum extent practicable to receive consideration
for the exemptions:
A.
Design around and limit disturbance of floodplains, wetlands, natural
slopes over 15%, existing native vegetation, and other sensitive and
special value features.
B.
Maintain riparian and forested buffers.
C.
Limit grading and maintain nonerosive flow conditions in natural
flow paths.
D.
Maintain existing tree canopies near impervious areas.
E.
Minimize soil disturbance and reclaim disturbed areas with topsoil
and vegetation.
F.
Direct runoff to pervious areas.
3.
The applicant must demonstrate that the proposed development/additional
impervious area will not adversely impact the following:
4.
An applicant proposing regulated activities may be eligible for exemption
from rate control, volume control, or stormwater management site plan
requirements in this chapter according to the following table:
|
Table 302.1 - 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 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[1] shall be used to document new impervious surfaces.
|
[1]
Editor's Note: Said appendix is included as an attachment
to this chapter.
5.
6.
An applicant proposing regulated activities, after demonstrating compliance with § 26-302, Subsections 1, 2, and 3, 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.
7.
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:
A.
The Township, in consultation with the PADEP (or delegated authority), determines that meeting the volume control requirements (see § 26-304) is not possible or places an undue hardship on the applicant.
B.
The alternative controls are documented to be acceptable to PADEP
(or delegated authority), for NPDES requirements pertaining to post-construction
stormwater management requirements.
8.
Agricultural activities are 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.
9.
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 and provisions shall be provided
to ensure the safety of downstream properties and waterways.
10.
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.
[Ord. No. 383, 8/27/2019]
1.
The provisions of this chapter are the minimum standards for the
protection of the public welfare.
3.
If an applicant demonstrates to the satisfaction of the governing body of the Township 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 §§ 26-102 and 26-103 of this chapter, the governing body of the Township 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.
4.
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 chapter.
5.
The Township shall keep a written record of all actions on waiver
requests.
6.
All waiver requests must be accompanied by a fee set by resolution
by North Strabane Township; the fee being designed to cover the administrative
costs of reviewing the waiver request. The Township shall 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 Township for reasonable and necessary fees that may
be incurred by the Township Engineer and Solicitor in any review of
a waiver request.
7.
In granting waivers, the Township shall impose reasonable conditions
that will, in its judgment, secure substantially the objectives of
the standards or requirements that are to be modified.
8.
The Township may grant applications for waivers when the following
findings are made, as relevant:
A.
That the waiver shall result in an equal or better means of complying
with the intent of this chapter.
B.
That the waiver is the minimum necessary to provide relief.
C.
That the applicant is not requesting a waiver based on cost considerations.
D.
That existing down gradient stormwater problems will not be exacerbated.
E.
That increased flooding or ponding on off-site properties or roadways
will not occur.
F.
That potential icing conditions will not occur.
G.
That increase of peak flow or volume from the site will not occur.
H.
That erosive conditions due to increased peak flows or volume will
not occur.
I.
That adverse impact to water quality will not result.
J.
That increased 100-year floodplain levels will not result.
K.
That increased or unusual municipal maintenance expenses will not
result from the waiver.
L.
That careful consideration has been given to the use of infiltration
measures where practicable and pre-development groundwater recharge
protected.
M.
That peak flow attenuation of runoff has been provided.
N.
That long-term operation and maintenance activities are established.
O.
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.
[Ord. No. 383, 8/27/2019]
2.
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, the intrinsic limitations on applicability
of the analytical procedures associated with each methodology, and
other factors.
A.
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.
(1)
Do not increase the post-development total runoff volume when
compared to the pre-development total runoff volume for the two-year/twenty-four-hour
storm event.
(2)
For hydrologic modeling purposes:
(a)
Existing nonforested pervious areas must be considered meadow
(good condition) for pre-development hydrologic calculations.
(b)
Twenty percent of existing impervious area, when present within
the proposed project site, shall be considered meadow (good condition)
for pre-development hydrologic calculations for redevelopment.
B.
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:
(1)
Stormwater facilities shall capture at least the first two inches
of runoff from all new impervious surfaces.
(2)
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.
(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.
(4)
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. Notification of the
Township shall be provided to allow witnessing of the testing.
3.
The applicable worksheets from the BMP Manual must be used in calculations
to establish volume control.
[Ord. No. 383, 8/27/2019]
1.
Lands contained within Washington County that have not had release
rates established under an approved Act 167 Stormwater Management
Plan:
A.
Post-development discharge rates shall not exceed the pre-development
discharge rates for the one-, two-, ten-, twenty-five-, fifty-, and
100-year storms.
[Ord. No. 383, 8/27/2019]
1.
Sensitive areas and water quality sensitive developments as defined
below which require special consideration with regard to stormwater
management.
A.
"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. North Strabane Township
may update the sensitive area boundaries based on new research or
studies as required.
B.
"Stormwater hotspots" are defined as a land development project that
has a high potential to endanger local water quality, and could potentially
threaten ground water reservoirs. The Township 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.
2.
Performance Standards.
A.
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.
B.
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.
C.
Stormwater hotspots must use an acceptable pre-treatment BMP prior
to volume control and/or rate control BMPs. Acceptable pre-treatment
BMPs for these developments include those based on filtering, settling,
or chemical reaction processes such as coagulation.
