1.
For all regulated activities, unless specifically exempted in § 19-302:
A.
Preparation and implementation of an approved SWM Site Plan is required.
B.
No regulated activities shall commence until Susquehanna Township
issues written approval of a SWM Site Plan, which demonstrates compliance
with the requirements of this Chapter.
D.
The SWM Site Plan approved by Susquehanna 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 Title 25 of the Pennsylvania 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 Chapter and to meet all requirements under
Title 25 of the Pennsylvania 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 Susquehanna Township.
4.
Susquehanna Township may, after consultation with PADEP and/or DCCD,
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.
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 Chapter 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.
C.
Applicants are encouraged to incorporate the techniques for low impact
development practices described in the Pennsylvania Stormwater Best
Management Practices Manual (BMP Manual) to reduce the costs of complying
with the requirements of this Chapter and the State Water Quality
Requirements.
6.
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 Chapter.
C.
For projects that add impervious area to a developed parcel, the
new impervious area is subject to the requirements of this Chapter,
and any existing impervious area that is within the new proposed limit
of disturbance is also subject to the requirements of this Chapter.
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.
A.
The applicant must provide an executed easement for newly concentrated
flow across adjacent properties.
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 Chapter.
9.
Where watercourses traverse a development site, drainage easements
(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 drainageways
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 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.
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 which may be required to pass storms larger than one-hundred-year
event.
13.
Any stormwater management facilities regulated by this Chapter that
will be located on or discharge onto state highway rights-of-way shall
be subject to approval by the Pennsylvania Department of Transportation
(PennDOT).
14.
When stormwater management facilities are proposed within 1,000 feet
of a downstream municipality, the stormwater analysis shall be submitted
to the downstream municipality's engineer for review and comment.
15.
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.
16.
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.
17.
The design of facilities over karst shall include an evaluation and
implementation of measures to minimize adverse effects.
18.
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 Susquehanna Township shall permit it on a case-by-case
basis.
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, after demonstrating
compliance with §§ 19-302.1, 19-302.2 and 19-302.3,
may be exempted from various requirements of this Chapter according
to the following table:
|
New Impervious Area
[Since the Date of Adoption of this Chapter]
(square footage)
|
Applicant Must Submit to Susquehanna Township
| |
|---|---|---|
|
0 - 1,000
|
—
| |
|
1,000 - 5,000
|
Volume Controls and SWM Site Plan and Report
| |
|
>5,000
|
Rate Controls, Volume Controls, SWM Site Plan and Report and
Record Drawings
|
5.
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. Susquehanna Township may accept alternative stormwater
management controls, provided that:
A.
The applicant, in consultation with Susquehanna Township, PADEP and/or
DCCD, states that meeting the requirements of the volume controls
or rate controls of this Chapter is not possible or creates an undue
hardship.
B.
The alternative stormwater management controls, proposed by the applicant,
are documented to be acceptable to Susquehanna Township, PADEP and/or
DCCD for NPDES requirements pertaining to post-construction stormwater
management requirements.
C.
The alternative stormwater management controls are in compliance
with all other sections of this Chapter, including but not limited
to §§ 19-301.4, 19-302.1, 19-302.2 and 19-302.3.
6.
Forest management and timber operations are exempt from rate and
volume control requirements 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.
7.
Agricultural activities are exempt from the requirements of this
Chapter, provided the activities are performed according to the requirements
of 25 Pa. Code Chapter 102.
8.
Linear roadway improvement projects that create additional impervious
area are not exempt from the requirements of this Chapter. However,
alternative stormwater management strategies may be applied at the
joint approval of Susquehanna Township and the Dauphin County Conservation
District (if an NPDES permit is required) when site limitations (such
as limited right-of-way) and constraints (as shown and provided by
the applicant), preclude the ability of the applicant to meet the
enforcement of the stormwater management standards in this Chapter.
All strategies must be consistent with PADEP's regulations, including
NPDES requirements.
9.
Susquehanna Township may, after an applicant has demonstrated compliance
with §§ 19-302.1, 19-302.2 and 19-302.3, grant a modification
of the requirements of one or more provisions of this Chapter if the
literal enforcement will exact undue hardship because of peculiar
conditions pertaining to the land in question, provided that such
modification will not be contrary to the public interest and that
the purpose and intent of the Ordinance is observed.
A.
All requests for a modification shall be in writing and shall state
in full the grounds and facts of unreasonableness or hardship on which
the request is based, the provision or provisions of the Ordinance
involved, and the minimum modification necessary.
2.
Stormwater runoff volume controls shall be implemented using the
design storm method or the simplified method. For regulated activities
equal to or less than one acre, this Chapter 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 predevelopment 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 predevelopment hydrologic calculations.
(b)
Twenty percent of existing impervious area, when present on
the proposed project site, and contained within the new proposed limit
of disturbance, shall be considered meadow (good condition) for predevelopment
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. 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.
3.
All applicable worksheets from Chapter 8 of the BMP Manual must be used when establishing volume controls.
4.
Actual field infiltration tests at the location of the proposed elevation
of the stormwater BMPs are required when 5,000 square feet or greater
of new impervious surface is added. Infiltration test shall be conducted
in accordance with BMP Manual. Susquehanna Township shall be notified
24 hours prior to infiltration tests being conducted as to provide
an opportunity for Susquehanna Township to witness the tests.
1.
Lands contained within Susquehanna Township that have not had release
rates established under an approved Act 167 Stormwater Management
Plan:
A.
Post-development discharge rates shall not exceed the predevelopment
discharge rates for the one-, two-, ten-, twenty-five-, fifty-, and
one-hundred-year storms.
2.
Lands contained within Susquehanna Township that have had release
rates established under an approved watershed-wide Act 167 Stormwater
Management Plan [Paxton Creek, Spring Creek (West), and Fishing Creek]:
A.
Post-development discharge rates shall not exceed the predevelopment
discharge rates for the one-, fifty-, and one-hundred-year storms.
B.
For the two-, ten-, and twenty-five-year storms, the post-development
peak discharge rates shall be in accordance with the approved release
rate map for the individual watershed.
3.
For lands contained within a Paxton Creek Watershed Provisional No
Detention District:
A.
These watershed areas may discharge post-development peak runoff without detention facilities. However, the applicant must prove that the "local" runoff conveyance facility which transports runoff from the site to the main channel has adequate capacity to safely transport unattenuated increased peak flows for a twenty-five-year storm in accordance with § 19-305. If there is inadequate capacity, the applicant shall either use 100% release rate control or provide increased capacity of downstream drainage facilities to convey increase peak flows consistent with § 19-305. When determining if adequate capacity exists in the local watershed drainage network, the applicant must assume that the entire local watershed is developed per current zoning and that all new development will use the least restrictive runoff controls specified by this Chapter.
4.
Off-site areas that drain through a proposed development site are
not subject to release rate criteria when determining allowable peak
runoff rate; however, on-site drainage facilities shall be designed
to safely convey off-site flows through the development site.
5.
For a proposed development site which is located within two or more
release rate districts, the maximum runoff discharged at any point
shall be equal to the release rate for the district in which the discharge
point is located. In the even that a portion of the site is located
in a provisional no detention area, no runoff from portions of the
site located in areas subject to release rate controls may be drained
to or through the provisional no detention area.
Any downstream capacity hydraulic analysis conducted in accordance
with this Chapter shall use the following criteria for determining
adequacy for accepting increased peak flow rates:
A.
Natural or man-made channels or swales must be able to convey the
increased runoff associated with a twenty-five-year return period
event within their banks at velocities consistent with protection
of the channels from erosion. Acceptable velocities shall be based
upon criteria included in the PADEP Erosion and Sediment Pollution
Control Program Manual.
B.
Natural or man-made channels or swales must be able to convey the
increased twenty-five-year return period runoff without creating any
hazard to persons or property.
C.
Culverts, bridges, storm sewers, or any other facilities which must
pass or convey flows from the tributary area must be designed in accordance
with PADEP Chapter 105 regulations (if applicable) and, at a minimum,
pass the increased twenty-five-year return period runoff, except for
facilities located within a designated floodplain area which must,
at a minimum, conform to FEMA and local floodplain ordinance requirements.
