The following permit requirements may apply
to certain regulated earth disturbance activities and must be met
prior to commencement of regulated earth disturbance activities, as
applicable:
A. All regulated earth disturbance activities subject
to permit requirements by DEP under regulations at 25 Pa. Code Chapter
102.
B. Work within natural drainageways subject to permit
by DEP under 25 Pa. Code Chapter 105.
C. Any stormwater management facility that would be located
in or adjacent to surface waters of the commonwealth, including wetlands,
subject to permit by DEP under 25 Pa. Code Chapter 105.
D. Any stormwater management facility that would be located
on a state highway right-of-way or require access from a state highway
shall be subject to approval by PennDOT.
E. Culverts, bridges, storm sewers, or any other facilities
which must pass or convey flows from the tributary area and any facility
which may constitute a dam subject to permit by DEP under 25 Pa. Code
Chapter 105.
Maximizing the groundwater recharge capacity of the area being developed is required. Design of the infiltration facilities shall consider groundwater recharge to compensate for the reduction in the recharge that occurs when the ground surface is disturbed or impervious surface is created. It is recommended that roof runoff be directed to infiltration BMPs that may be designed to compensate for the runoff from parking areas. These measures are required to be consistent with §
203-36 and to take advantage of utilizing any existing recharge areas. Infiltration may not be feasible on every site due to site-specific limitations such as soil type. If it cannot be physically accomplished, then the design professional shall be responsible to show that this cannot be physically accomplished. Appropriate soils testing and/or geotechnical evaluation should be included as part of any documentation for infiltration BMPs. If it can be physically accomplished, then the volume of runoff to be infiltrated shall be determined from §
203-53A(2).
A. Infiltration BMPs shall meet the following minimum
requirements.
(1) Infiltration BMPs intended to receive runoff from
developed areas shall be selected based on suitability of soils and
site conditions and shall be constructed on soils that have the following
characteristics:
(a)
A minimum depth of 24 inches, preferably 36
inches, between the bottom of the BMP and the top of the limiting
zone, e.g., seasonal high-water table, groundwater, bedrock, etc.
(b)
An infiltration rate sufficient to accept the
additional stormwater load and dewater completely as determined by
field tests conducted by the applicant's design professional.
(c)
The infiltration facility shall be capable of
completely infiltrating the recharge (infiltration) volume (Rev) within three days (72 hours) or less.
(d)
Pretreatment shall be provided prior to infiltration.
(2) The size of the infiltration facility shall be based
upon the Net Two-Year Volume Approach, where the recharge (infiltration)
volume (Rev) to be captured and infiltrated
shall be the volume difference between the predevelopment two-year
twenty-four-hour storm event and post-development two-year twenty-four-hour
storm event.
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The recharge volume calculated using this section
is the minimum volume the applicant must control through an infiltration
BMP facility. However, if a site has areas of soils where additional
volume of recharge can be achieved, the applicant is encouraged to
infiltrate as much of the stormwater runoff from the site as possible.
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B. Soils. A detailed soils evaluation of the project
site shall be required to determine the suitability of infiltration
facilities. The evaluation shall be performed by a qualified design
professional and at a minimum address soil permeability, depth to
bedrock, and subgrade stability. The general process for designing
the infiltration BMP shall be:
(1) Analyze hydrologic soil groups and all natural and
artificial features on the site to determine general areas of suitability
for infiltration practices. In areas where development on fill material
is considered, conduct geotechnical investigations of subgrade stability;
infiltration may not be ruled out without conducting these tests.
(2) Provide field tests such as double ring infiltrometer
or hydraulic conductivity tests (at the level of the proposed infiltration
surface) to determine the appropriate hydraulic conductivity rate.
Percolation tests are not recommended for design purposes.
(3) Design the infiltration structure for the required
recharge (Rev) volume based on field-determined
capacity at the level of the proposed infiltration surface.
(4) If on-lot infiltration structures are proposed by
the applicant's design professional, it must be demonstrated to the
Township that the soils are conducive to infiltrate on the lots identified.
C. Stormwater hot spots:
(1) Below is a list of examples of designated hot spots.
If a site is designated as a hot spot, it has important implications
for how stormwater is managed. First and foremost, untreated stormwater
runoff from hot spots shall not be allowed to recharge into groundwater
where it may contaminate water supplies. Therefore, the Rev requirement shall NOT be applied to development sites
that fit into the hot spot category (the entire WQv must still be treated). Second, a greater level of stormwater treatment
shall be considered at hot spot sites to prevent pollutant runoff
after construction. The Environmental Protection Agency's (EPA) NPDES
stormwater program requires some industrial sites to prepare and implement
a stormwater pollution prevention plan.
(a)
Examples of hot spots:
[1]
Vehicle salvage yards and recycling facilities.
[2]
Vehicle fueling stations.
[3]
Vehicle service and maintenance facilities.
[4]
Vehicle and equipment cleaning facilities.
[5]
Fleet storage areas (bus, truck, etc.).
[6]
Industrial sites based on Standard Industrial
Codes.
[7]
Marinas (service and maintenance).
[8]
Outdoor liquid container storage.
[9]
Outdoor loading/unloading facilities.
[10] Public works storage areas.
[11] Facilities that generate or store
hazardous materials.
[12] Commercial container nursery.
[13] Other land uses and activities
as designated by an appropriate review authority.
(b)
The following land uses and activities are not
normally considered hot spots:
[1]
Residential streets and rural highways.
[3]
Institutional development.
[6]
Pervious areas, except golf courses and nurseries,
which may need an integrated pest management (IPM) plan.
(2) While large highways with an average daily traffic
volume greater than 30,000 are not designated as stormwater hot spots,
it is important to ensure that highway stormwater management plans
adequately protect groundwater.
D. Extreme caution shall be exercised where infiltration
is proposed in SWPAs, as defined by the local Township or water authority.
E. Infiltration facilities shall be used in conjunction
with other innovative or traditional BMPs, stormwater control facilities,
and nonstructural stormwater management alternatives.
F. Extreme caution shall be exercised where salt or chloride,
i.e., salt storage areas, would be a pollutant, since soils do not
filter this pollutant and it contaminates the groundwater. A design
professional shall evaluate the possibility of groundwater contamination
from the proposed infiltration facility and perform a hydrogeologic
justification study if necessary. Specific consideration should be
given to the particular type of salt or deicing material to be used
within this watershed in regards to its potential long-term effects
on the soils, especially in areas that contain clay soil.
G. The infiltration requirement in HQ or EV waters shall
be subject to the DEP's Chapter 93 Antidegradation Regulations.
H. An impermeable liner is required in detention basins
where the possibility of groundwater contamination exists. A detailed
hydrogeologic investigation may be required by the Township.
I. The Township shall require the applicant to provide
safeguards against groundwater contamination for land uses that may
cause groundwater contamination should there be a mishap or spill.
The applicant shall comply with the following
water quality requirements of this article.
A. No regulated earth disturbance activities within the
Township shall commence until approval by the Township of a plan that
demonstrates compliance with post-construction state water quality
requirements.
B. The BMPs shall be designed, implemented, and maintained
to meet DEP water quality requirements and any other more stringent
requirements as determined by the Township.
C. To control post-construction stormwater impacts from
regulated earth disturbance activities, state water quality requirements
can be met by BMPs, including site design, which provide for replication
of preconstruction stormwater infiltration and runoff conditions so
that post-construction stormwater discharges do not degrade the physical,
chemical or biological characteristics of the receiving waters. As
described in the DEP Comprehensive Stormwater Management Policy (No.
392-0300-002, September 28, 2002), this may be achieved by the following:
(1) Infiltration: replication of preconstruction stormwater
infiltration conditions;
(2) Treatment: use of water quality treatment BMPs to
ensure filtering out of the chemical and physical pollutants from
the stormwater runoff; and
(3) Stream bank and streambed protection: management of
volume and rate of post-construction stormwater discharges to prevent
physical degradation of receiving waters (e.g., from scouring).
D. Water quality volume.
(1) Developed areas shall provide adequate storage and treatment facilities necessary to capture and treat stormwater runoff. If site conditions allow for infiltration, the water quality volume and the recharge volume are the same volume and may be managed in a single facility. If infiltration cannot be physically accomplished, the water quality volume should be calculated using the Net Two-Year Volume Approach described in §
203-53A(2). In this case, the water quality volume may be captured and treated by methods other than infiltration BMPs.
(2) This volume requirement can be accomplished by the
permanent volume of a wet basin or the detained volume from other
BMPs. Where appropriate, wet basins shall be utilized for water quality
control and shall follow the guidelines of the BMP manuals referenced
in Appendix E.
(3) The water quality volume shall take a minimum of 24
hours to be discharged from a BMP facility. Release of the water quality
volume can begin at the start of the storm (i.e., the invert of the
water quality orifice is at the invert of the facility). The design
of the facility shall provide for protection from clogging and unwanted
sedimentation.
E. For areas within defined special protection subwatersheds
that include EV and HQ waters, the temperature and quality of water
and streams shall be maintained through the use of temperature-sensitive
BMPs and stormwater conveyance systems.
F. To accomplish the above, the applicant shall submit
original and innovative designs to the Township Engineer for review
and approval. Such designs may achieve the water quality objectives
through a combination of different BMPs.
G. If a perennial or intermittent stream passes through
the site, the applicant shall create a stream buffer extending a minimum
of 50 feet to either side of the top-of-bank of the channel. The buffer
area shall be maintained with and encouraged to use appropriate native
vegetation (refer to Appendix B of the Pennsylvania Stormwater Best
Management Practices Manual for plant lists). If the applicable rear
or side yard setback is less than 50 feet or a stream traverses the
site, the buffer width may be reduced to 25% of the setback and/or
to a minimum of 10 feet. If an existing buffer is legally prescribed,
i.e., by deed, covenant, easement, etc., and it exceeds the requirements
of this part, the existing buffer shall be maintained. This does not
include lakes or wetlands.
H. Evidence of any necessary permit(s) for regulated
earth disturbance activities from the appropriate DEP regional office
must be provided to the Township.