[Ord. 2011-01, 4/7/2011, § 301]
1.
For all regulated activities, unless specifically exempted in § 26-222:
A.
Preparation and implementation of an approved SWM site plan is required.
B.
No regulated activities shall commence until the municipality issues
written approval of a SWM site plan, which demonstrates compliance
with the requirements of this Part.
D.
The SWM site plan approved by the municipality, 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 Part and to meet all
requirements under Title 25 of the Pa. 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.
3.
For all regulated activities, stormwater BMPs shall be designed,
installed, implemented, operated, and maintained to meet the purposes
and requirements of this Part and to meet all requirements under Title
25 of the Pa. Code and the Clean Streams Law, 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 municipality.
4.
The municipality may, after consultation with PADEP, approve measures
for meeting the state water quality requirements other than those
in this part, 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.
All regulated activities shall include, to the maximum extent practicable,
measures to:
A.
Protect health, safety, and property.
B.
Meet the water quality goals of this Part by implementing measures
to:
(1)
Minimize disturbance to floodplains, wetlands, natural slopes,
existing native vegetation and woodlands.
(2)
Create, maintain, or extend riparian buffers and protect 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.
6.
Impervious Areas.
7.
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.
8.
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.
9.
Where watercourses traverse a development site, drainage easements
(to encompass the one-hundred-year flood elevation with a minimum
width of 20 feet) 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.
10.
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.
11.
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, 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.
12.
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.
13.
Any stormwater management facilities regulated by this Part 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).
14.
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.
15.
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.
16.
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. When it is more advantageous to connect directly to streets
or storm sewers, then the municipality may permit it on a case-by-case
basis based upon the advise and recommendations of its engineer.
17.
Applicants are encouraged to use low impact development practices
to comply with the requirements of this Part and the state water quality
requirements.
18.
When stormwater management facilities are proposed within 1,000 feet
of a downstream municipality, the developer shall notify the downstream
municipality and, upon request, provide the SWM plan to the downstream
municipality's engineer for review and comment.
[Ord. 2011-01, 4/7/2011, § 302]
2.
The applicant must utilize the following BMPs 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 non-erosive 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's proposed development/additional impervious area
may not adversely impact the following:
4.
An applicant proposing regulated activities, after demonstrating compliance with Subsections 1, 2, and 3 may be exempted from the SWM site plan, rate control, or volume control requirements of this Part according to the following table:
|
Exemption Table
| |
|---|---|
|
New Impervious Area1,2
(square footage)
|
Applicant Must Provide
|
|
0-1,000
| |
|
> 1,000-2,500
|
Documentation of new impervious surface3
|
|
> 2,500-5,000
|
Volume controls and 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 Part.
|
|
2
|
Unless otherwise demonstrated to the satisfaction of the Municipal
Engineer, gravel in existing condition shall be considered pervious
and gravel in proposed condition shall be considered impervious. Existing
maintained municipal roads are considered impervious.
|
|
3
|
The small project stormwater management application included in Appendix D shall be used to establish eligibility for the exemptions listed in the above table for projects under 5,000 sq. ft. or for single family home construction. The small project SWM application satisfies the requirement for demonstrating compliance with Subsections 1, 2 and 3 and for documentation of new impervious surface; credits for disconnection of impervious surfaces and tree planting; and for computing the size of volume control BMP's, when required.
|
5.
An applicant proposing regulated activities, after demonstrating compliance with Subsections 1, 2, and 3, may be exempted from various requirements of this Part 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.
6.
The purpose 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:
A.
The municipality, in consultation with the PADEP, determines that meeting the volume control requirements (see § 26-224) is not possible or places an undue hardship on the applicant.
B.
The alternative controls are documented to be acceptable to PADEP,
for NPDES requirements pertaining to post construction stormwater
management requirements.
7.
Agricultural activity is exempt from the rate control and SWM site
plan preparation requirements of this Part provided the activities
are performed according to the requirements of 25 Pa. Code, Chapter
102.
8.
Forest management and timber operations are exempt from the rate
and volume control requirement and SWM site plan preparation requirement
of this Part 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.
[Ord. 2011-01, 4/7/2011, § 303]
1.
The provisions of this Part are the minimum standards for the protection
of the public welfare.
2.
All waiver requests must meet the provisions of Subsections 7 and 8. Waivers shall not be issued from implementing such measures as necessary to:
3.
If an applicant demonstrates to the satisfaction of the governing body of the municipality that any mandatory provision of this Part 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 §§ 26-202 and 26-203 of this Part, 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 Part.
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 this Part 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.
5.
The municipality shall keep a written record of all actions on waiver
requests.
6.
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 by the Municipal
Engineer in any review of a waiver request.
7.
In granting waivers, the municipality may impose reasonable conditions
at will, in its judgment, secure substantially the objectives of the
standards or requirements that are to be modified.
8.
The municipality 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 Part.
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 runoff is not being diverted to a different drainage area.
F.
That increased flooding or ponding on off-site properties or roadways
will not occur.
G.
That potential icing conditions will not occur.
H.
That increase of peak flow (design storms up to one-hundred-year)
or volume (design storms up to two-year) from the site will not occur.
I.
That erosive conditions due to increased peak flows or volume will
not occur.
J.
That adverse impact to water quality will not result.
K.
That increased one-hundred-year floodplain levels will not result.
L.
That increased or unusual municipal maintenance expenses will not
result from the waiver.
M.
That the amount of stormwater generated has been minimized to the
greatest extent allowed.
N.
That infiltration of runoff throughout the proposed site has been
provided where practicable and pre-development ground water recharge
protected.
O.
That peak flow attenuation of runoff has been provided.
P.
That long term operation and maintenance activities are established.
Q.
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. 2011-01, 4/7/2011, § 304]
1.
The low impact development practices provided in the BMP manual and
in Appendix B of this Part shall be utilized for all regulated activities
to the maximum extent practicable.
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 Part
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.
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 non-forested 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
municipality shall be provided to allow witnessing of the testing.
C.
In cases where it is not possible or desirable to use infiltration-based
best management practices to partially fulfill the requirements in
either Subsection 2A or B, the following procedure shall be used:
(1)
At a minimum, the following documentation shall be provided
to justify the decision to not use infiltration BMPs:
(a)
Description of and justification for field infiltration/permeability
testing with respect to the type of test and test locations).
(b)
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.
(c)
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.
(d)
The provided documentation must be signed and sealed by a professional
engineer or geologist.
(2)
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
|
(3)
The performance criteria for water quality best management practices
shall be determined from the Pennsylvania Stormwater Best Management
Practices Manual, most current version.
3.
The applicable worksheets from the BMP manual must be used in calculations
to establish volume control. Worksheets documenting volume control
credits are also acceptable.
[Ord. 2011-01, 4/7/2011, § 305]
1.
For lands contained within Crawford 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
one-hundred-year storms.
2.
For lands contained within Crawford County that have had release
rates established under an approved Act 167 Stormwater Management
Plan:
A.
The post-development peak discharge rates shall be in accordance
with the approved release rate map for the individual watershed.
(1)
Conneaut Outlet Watershed. For the two-, ten-, twenty-five-
and one-hundred-year storms, post-development peak discharge rates
shall follow the approved release rate map included in Appendix E[1] or as available from the municipality.
[1]
Editor's Note: Appendix E is on file in the Township
offices.
[Ord. 2011-01, 4/7/2011, § 306]
1.
"Sensitive areas" and "stormwater hotspots" as defined in Subsection
1A and B respectively 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. Municipalities may update the
sensitive area boundaries based on new research or studies as required.
B.
Stormwater hotspots are land development projects that have a high
potential to endanger local water quality, and could potentially threaten
ground water reservoirs. 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. Industrial sites referenced in 40 CFR 125 are also
examples of "stormwater hotspots."
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 hotspot developments 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 hotspot developments 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.
