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 PADEP under regulations at Title 25, Pennsylvania Code, Chapter
102.
B. Work within natural drainageways subject to permit by PADEP under Title 25, Pennsylvania 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 PADEP under Title 25, Pennsylvania Code, Chapter
105.
D. Any stormwater management facility that would be located on or discharging
to a state highway right-of-way or require access to or 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 PADEP under Title 25, Pennsylvania Code, Chapter
105.
The design of all regulated activities shall include the following
to minimize stormwater impacts to reduce the surface discharge of
stormwater, reduce the creation of unnecessary impervious surfaces,
prevent the degradation of waters of the commonwealth, and maintain
as much as possible the natural hydrologic regime of the site:
A. The applicant may apply low-impact development (LID) methods such
as those listed in Appendix D, provided that use of this method does
not conflict with other local codes.
B. The applicant shall demonstrate that the design process follows the
sequence noted below. The goal of the sequence is to minimize the
increases in stormwater runoff and impacts to water quality resulting
from the proposed regulated activity:
(1)
The following items in this subsection shall be addressed prior
to development of other stormwater management site plan design elements:
(a)
Prepare an existing resource and site analysis map (ERSAM) showing
environmentally sensitive areas, including, but not limited to, steep
slopes, ponds, lakes, streams, wetlands, hydric soils, vernal pools,
stream buffers, and hydrologic soil groups. Land development, any
existing recharge areas, and other requirements outlined in the municipal
SALDO shall also be included.
(c)
Prepare a draft project layout avoiding sensitive areas identified in §
105-304B(1)(a).
(d)
Identify site-specific existing conditions drainage areas, discharge
points, recharge areas, and Hydrologic Soil Groups A and B (areas
conducive to infiltration).
(e)
Evaluate nonstructural stormwater management alternatives:
[1]
Minimize earth disturbance.
[2]
Minimize impervious surfaces.
[3]
Break up large impervious surfaces.
(f)
Determine into what management district the site falls (Appendix
A), and conduct an existing conditions' runoff analysis.
(2)
The following items in this subsection may be addressed in any order, provided that all items in §
105-304B(1) have been completed.
(a)
Satisfy the infiltration objective (§
105-305) and provide for stormwater pretreatment prior to infiltration.
(b)
Provide for water quality protection in accordance with §
105-306, Water quality requirements.
(c)
Provide stream bank erosion protection in accordance with §
105-307, Stream bank erosion requirements.
(d)
Prepare a final project design to maintain existing conditions'
drainage areas and discharge points, to minimize earth disturbance
and impervious surfaces and, to the maximum extent possible, to ensure
that the remaining site development has no surface or point discharge.
(e)
Conduct a proposed conditions' runoff analysis based on the final design that meets the management district requirements (§
105-308).
(f)
Manage any remaining runoff prior to discharge through detention,
bioretention, direct discharge, or other structural control.
The applicant shall comply with the following water quality
requirements of this article:
A. To control post-construction stormwater impacts from regulated activities
and conform to state water quality requirements, BMPs which replicate
predevelopment stormwater infiltration and runoff conditions must
be provided in the site design such that post-construction stormwater
discharges do not degrade the physical, chemical, or biological characteristics
of the receiving waters. This may be achieved by the following:
(1)
Infiltration: replication of preconstruction stormwater infiltration
conditions;
(2)
Treatment: use of water quality treatment BMPs to provide filtering
of chemical and physical pollutants from the stormwater runoff; and
(3)
Stream bank and stream bed protection: management of volume
and rate of post-construction stormwater discharges to prevent physical
degradation of receiving waters (e.g., from scouring).
B. Developed areas shall provide adequate storage and treatment facilities necessary to capture and treat stormwater runoff. The infiltration volume computed under §
105-305 may be a component of the water quality volume if the applicant chooses to manage both components in a single facility. If the calculated water quality volume (WQ
v) is greater than the volume required to be infiltrated as described in §
105-305C(2), then the difference between the two volumes shall be treated for water quality by an acceptable stormwater management practice(s). The required water quality volume (WQ
v) is the storage capacity needed to capture
and treat a portion of stormwater runoff from the developed areas
of the site.
(1)
To achieve this requirement, the following criterion is established:
(a)
From Control Guideline 1 (CG-1) in the PA BMP Manual, the water
quality volume shall be the net two-year, twenty-four-hour volume.
The net volume is the difference between the post-development runoff
volume and the predevelopment runoff volume. The post-development
total runoff volume for all storms equal to or less than the two-year,
twenty-four-hour duration precipitation shall not be increased. For
modeling purposes, existing (predevelopment) nonforested pervious
areas must be considered meadow in good condition or its equivalent,
and 20% of existing impervious area, when present, shall be considered
meadow in good condition.
(2)
This volume requirement can be managed 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 PA BMP Manual referenced in Appendix B.
(3)
Release of water 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.
C. The temperature of receiving waters shall be protected through the
use of BMPs that moderate temperature.
D. If a perennial or intermittent stream passes through, or a water
body (i.e., lake, pond, and wetland) is present on the site, the applicant
shall create a riparian buffer extending a minimum of 50 feet to either
side of the top-of-bank of the channel, lake, or wetland. The buffer
area shall be planted with native vegetation and maintained in a vegetated
state (Refer to Appendix B, Pennsylvania Native Plant List, contained
in the PA BMP Manual).
(1)
The following provisions also apply to riparian buffers on lots
in existence at the time of adoption of this chapter:
(a)
If the applicable rear or side yard setback is less than 50
feet, the buffer width may be reduced to 25% of the setback or 25
feet, whichever is greater.
(b)
If a stream traverses a site in a manner that significantly
reduces the use of the site, the buffer may be either:
[1]
Reduced to 25 feet on either side, with municipal approval;
or
[2]
Reduced to 10 feet with municipal waiver; or
[3]
If an existing buffer is legally prescribed (e.g., deed covenant,
easement, etc.) and it exceeds the requirement of this chapter, the
existing buffer shall be maintained.
(2)
Permitted uses within the buffer include the following, subject
to municipal approval and provided that they comply with all federal,
state, and local regulations:
(a)
Recreational trails. See Appendix H, Riparian Buffer Trail Guidelines.
(d)
Other uses subject to municipal approval.
E. If an existing buffer is legally prescribed (i.e., deed, covenant,
easement, etc.) and it exceeds the requirements of this chapter, the
existing buffer shall be maintained.