No development plan, subdivision plat or land development plan
shall be approved; no permit authorizing construction or development
issued; nor any earth disturbance activity subject to this article
shall be initiated or undertaken unless and until a stormwater management
plan for such activity is reviewed and approved in accord with the
provisions of this chapter.
A.
No regulated development activities within the Township shall commence until approval by the Township of a stormwater management plan which demonstrates compliance with state water quality requirements after construction is complete. Refer to the Regulated Development Activity Table located in Article III of this chapter.
B.
The stormwater management plan must be designed, implemented and
maintained to meet state water quality requirements, and any other
more stringent requirements as determined by the Township.
C.
To control post-construction stormwater impacts from regulated development
activities, state water quality requirements can be met by BMPs, including
site design and green infrastructure, 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.
(3)
Stream bank and streambed protection. Management of volume and rate
of post-construction stormwater discharges, using detention/retention
and other means, to prevent physical degradation of receiving waters
(e.g., from scouring).
D.
In the absence of an existing stormwater conveyance or easement,
whether natural or man-made, for release of stormwater flow from a
development site, an easement must be provided. Information shall
be presented as to the ownership, responsible party, and agreement
for said easement.
E.
The stormwater management plan must meet DEP regulations that require
municipalities to ensure design, implementation and maintenance of
best management practices (BMPs) that control runoff from new development
and redevelopment after regulated development activities are complete.
These requirements include the need to implement post-construction
stormwater facilities and BMPs with assurance of long-term operations
and maintenance of those BMPs.
F.
Evidence of any necessary permit(s), such as Chapter 102 erosion and sedimentation control or Chapter 105 stream encroachment, for regulated development activities from WCD or the appropriate DEP regional office must be provided to the Township. The issuance of an NPDES construction permit [or permit coverage under the Statewide General Permit (PAG-2)] may satisfy the requirements of Subsection A above, after review and approval by the Township.
H.
The Township shall not approve any SWM plan that is deficient in
meeting the requirements of this chapter. At its sole discretion and
in accordance with this article, when a SWM plan is found to be deficient,
the Township may either disapprove the submission and require a resubmission,
or, in the case of minor deficiencies, the Township may accept submission
of modifications.
I.
Professional certification. The stormwater management plan (including
all calculations) must be prepared and sealed by a qualified professional
with training and expertise in hydrology and hydraulics. Documentation
of qualifications may be required by the Township.
General format. The stormwater management plan shall include
a narrative and a set of plan drawings. Refer to checklist Appendix
D.[1]
A.
A narrative describing the overall stormwater management concept
for the project.
(1)
A determination of site conditions in accordance with the PA DEP
Stormwater BMP Manual. A detailed site evaluation shall be completed
for projects' proposed environmentally sensitive areas, such
as brownfields.
(2)
Runoff calculations. Stormwater runoff design calculations for determining pre- and post-development discharge rates, for designing proposed stormwater control facilities and to demonstrate that the maximum practicable measures have been taken to meet the requirements of this chapter, must be submitted with the stormwater management plan. All calculations shall be prepared using the methods and data prescribed by general requirements in § 144-15. Refer to the Acceptable Computation Methodologies Table in Article III, § 144-19, of this chapter.
(a)
Runoff volume and rate shall be calculated according to generally
accepted methods such as those listed under Stormwater Management
Performance Standards, General Standards.
(b)
Detention/retention requirements, including volume, routing,
etc., for BMPs shall be calculated using commonly acceptable standard
methods.
(c)
Water quality calculations shall be determined by using the
PA DEP Stormwater BMP Manual 2006 or current edition, Worksheets 12
and 13, or acceptable alternative method by the municipality.
(3)
Expected project time schedule for the installation of all temporary
and permanent stormwater control measures and devices. If the development
is to be constructed in stages, the applicant must describe how stormwater
facilities and BMPs will be sequentially installed to manage stormwater
runoff safely during each stage of development.
(4)
The effect of the project (in terms of runoff rate, volumes, and
water quality) on surrounding properties and aquatic features and
on any existing stormwater conveyance system that may be affected
by the project.
(5)
If appropriate, the narrative should provide justification as to
why any preferred stormwater management techniques, such as LID and
green infrastructure, as listed in this chapter, are not proposed
for use. Refer to the PA DEP Stormwater BMP Manual 2006 or most recent
edition for a list of acceptable management techniques.
B.
The stormwater management plan drawings shall be drawn to a scale
of not less than one inch equals 100 feet. All sheets shall contain
a title block with name and address of applicant and designer, scale,
North arrow, legend and date of preparation.
(1)
Existing and proposed features. The plan shall show the following:
(a)
Watershed location. Provide a key map (using USGS Topo maps)
showing the location of the development site within the watershed(s)
and watershed subarea(s). On all site drawings, show the boundaries
of the watershed(s) and subarea(s) as they are located on the development
site and identify watershed name(s) and subarea number(s). Refer to
Appendix A, Watershed Performance District Maps.[2]
[2]
Editor's Note: Appendix A is included as an attachment to this chapter.
(b)
Floodplain boundaries. Identify 100-year floodplains on the
development site (as appropriate) based on the FEMA Flood Insurance
Rate Map(s) for the Township.
(c)
Natural features. Show all bodies of water (natural or artificial),
watercourses (permanent and intermittent), swales, wetlands and other
natural drainage courses on the development site, or which will be
affected by runoff from the development.
(d)
Soils. Provide an overlay showing soil types and boundaries
within the development site (consult WCD, SCS and U.S. Geological
Survey for information).
(e)
Contours. Show existing and final contours at intervals of two
feet; in areas with slopes greater than 15%, five-foot contour intervals
may be used.
(f)
Land cover. Show existing and final land cover classifications,
including existing and proposed improvements, as necessary to support
and illustrate the runoff calculations performed.
(g)
Drainage area delineations. Show the boundaries of the drainage
areas and points of interest employed in the runoff calculations performed.
(h)
Time of concentration flow paths. Show flow paths used for all
time of concentration calculations. Identify the different segments
of flow path used for travel time calculations for sheet flow, shallow
concentrated flow and channel flow regimes.
(i)
Utilities and easements. Show any existing utilities, stormwater
management or drainage controls and/or structures, such as sanitary
sewers, water, gas, electric, telecommunications, storm sewers, swales,
culverts, and any easements, which are located on the development
site, or which are off site but may be affected by runoff from the
development.
(2)
Proposed stormwater facilities and BMPs. All proposed stormwater
runoff control measures must be shown on the plan, including methods
for collecting, conveying and storing stormwater runoff on site, which
are to be used both during and after construction. Erosion and sedimentation
controls shall be shown in accordance with applicable Township and
WCD requirements. The plan shall provide information on the exact
type, location, sizing, design and construction of all proposed facilities
and relationship to the existing watershed drainage system.
(a)
If the development is to be constructed in stages, the applicant
must demonstrate that stormwater facilities will be installed to manage
stormwater runoff safely during each stage of development.
(b)
A schedule for the installation of all temporary and permanent
stormwater control measures and devices shall be included in the narrative
and shown on the site plan. This schedule shall include all stages
of construction identified as critical for the proper short-term and
long-term operation and performance of these control measures that
will need to be inspected by the stormwater design engineer, the Township
Engineer and/or the WCD.
(3)
Easements, rights-of-way, and deed restrictions. BMPs and stormwater
management facilities that provide control for more than one lot shall
be located on a separate dedicated lot or in an easement. All existing
and proposed easements for any BMPs and stormwater management facilities
and controls for access, inspections, maintenance, repair, preservation
and use shall be shown on the plan and, if required, dedicated to
the entity, association or person required. The easement and the purpose
for the same shall be set forth on the plan and in the agreement required
by this chapter.
[1]
Editor's Note: Appendix D is included as an attachment to this chapter.
A list of any approvals/permits relative to stormwater management
that will be required from other governmental agencies (e.g., Chapter
102 Erosion and Sedimentation Control, PennDOT Highway Occupancy Permit,
Chapter 105 Water Obstruction and Encroachment Permit from PA DEP)
and anticipated dates of submission/receipt should be included with
the stormwater plan submission. Copies of permit applications may
be requested by the Township where they may be helpful for the plan
review.
The application shall contain a proposed operation and maintenance plan (O & M) for all stormwater control facilities in accordance with the following and as described in Article VII of this chapter:
Submit financial guarantees in accordance with the provisions
of this chapter. Refer to Appendix E.[1]
[1]
Editor's Note: Appendix E is included as an attachment to this chapter.
