[Ord. 2125, 7/14/2014]
1.
For all regulated activities, unless preparation of an SWM site plan
is specifically exempted in § 222:
2.
SWM site plans approved by the municipality, in accordance with § 236,
shall be on site throughout the duration of the regulated activity.
3.
The municipality may, after consultation with the DEP, 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.
4.
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 Pennsylvania Code 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.
5.
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 development taking place in stages, the entire development plan
must be used in determining conformance with this Part.
C.
For projects that add impervious area to a parcel, the total impervious
area on the parcel is subject to the requirements of this Part, except
that the volume controls in § 223 and the peak rate controls
of § 224 do not need to be retrofitted to existing impervious
areas that are not being altered by the proposed regulated activity.
6.
Stormwater flows onto adjacent property shall not be created, increased,
decreased, relocated, or otherwise altered without written notification
of the adjacent property owner(s) by the developer. Such stormwater
flows shall be subject to the requirements of this Part.
7.
All regulated activities shall include such measures as necessary
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, and wooded areas.
(2)
Maintain or extend riparian buffers.
(3)
Avoid erosive flow conditions in natural flow pathways.
(4)
Minimize thermal impacts to waters of this commonwealth.
(5)
Disconnect impervious surfaces by directing runoff to pervious
areas, wherever possible.
C.
To the maximum extent practicable, incorporate the techniques for
low-impact development practices described in the Pennsylvania Stormwater
Best Management Practices Manual (BMP Manual).
8.
The design of all facilities over karst shall include an evaluation
of measures to minimize adverse effects.
9.
Infiltration BMPs should be spread out, 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.
10.
Normally dry, open-top, storage facilities should completely drain
both the volume control and rate control capacities over a period
of time not less than 24 and not more than 72 hours from the end of
the design storm.
11.
The design storm volumes to be used in the analysis of peak rates
of discharge should be obtained from the Precipitation-Frequency Atlas
of the United States, Atlas 14, Volume 2, Version 3.0, United States
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/.
12.
For all regulated activities, SWM BMPs shall be designed, implemented,
operated, and maintained to meet the purposes and requirements of
this Part and to meet all requirements under Title 25 of the Pennsylvania
Code, the Clean Streams Law,[1] and the Storm Water Management Act.
[1]
Editor's Note: See 35 P.S. § 691.1 et seq.
13.
Various BMPs and their design standards are listed in the BMP Manual.
[Ord. 2125, 7/14/2014]
1.
Regulated activities that result in cumulative earth disturbances
of less than 1,600 square feet are exempt from the requirements in
§§ 223, 224 and Subpart D of this Part.
[Amended by Ord. No. 2194, 3/9/2020]
2.
Agricultural activity is exempt from the SWM site plan preparation
requirements of this Part, provided the activities are performed according
to the requirements of 25 Pa. Code Chapter 102.
3.
Forest management and timber operations are exempt from the SWM site
plan preparation requirements of this Part, provided the activities
are performed according to the requirements of 25 Pa. Code Chapter
102.
4.
Exemptions from any provisions of this Part shall not relieve the applicant from the requirements in § 221, Subsections 4 through 11.
5.
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 and safety or the environment.
[Ord. 2125, 7/14/2014; as amended by Ord. No. 2217, 9/12/2022]
The green infrastructure and low-impact development practices
provided in the BMP Manual shall be utilized for all regulated activities
to the maximum extent practicable. Water volume controls shall be
implemented using the Design Storm Method in Subsection A or the Simplified
Method in Subsection B below. For regulated activity areas equal to
or less than one acre that do not require hydrologic routing to design
the stormwater facilities, this Part establishes no preference for
either methodology; therefore, the applicant may select either methodology
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 size of regulated activity. This method requires detailed modeling
based on site conditions.
1.
Do not increase the post-development total runoff volume for all
storms equal to or less than the two-year, twenty-four-hour duration
precipitation.
B.
The Simplified Method (CG-2 in the BMP Manual) provided below 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 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 the surface waters of this 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.
This method is exempt from the requirements of § 224, Rate
Controls.
[Ord. 2125, 7/14/2014; as amended by Ord. No. 2217, 9/12/2022]
For areas not covered by a release rate map from an approved
Act 167 Stormwater Management Plan, post-development discharge rates
shall not exceed the predevelopment discharge rates for the one-,
two-, five-, ten-, twenty-five-, fifty-, and one-hundred-year, twenty-four-hour
storms. If it is shown that the peak rates of discharge indicated
by the post-development analysis are less than or equal to the peak
rates of discharge indicated by the predevelopment analysis for one-,
two-, five-, ten-, twenty-five-, fifty-, and one-hundred-year, twenty-four-hour
storms, then the requirements of this section have been met. Otherwise,
the applicant shall provide additional controls as necessary to satisfy
the peak rate of discharge requirement.
