A.
For all regulated activities, unless preparation of an SWM site plan is specifically exempted in § 149-15:
B.
All SWM site plans for regulated activities shall include such measures
as necessary to:
(1)
Protect health, safety, and property.
(2)
Meet the water quality goals of this chapter, as stated in § 149-3, by including measures that:
(a)
Minimize disturbance to floodplains, wetlands, wooded areas,
and existing vegetation.
(b)
Maintain or extend riparian buffers.
(c)
Avoid erosive flow conditions in natural flow pathways.
(d)
Minimize thermal impacts to waters of the commonwealth.
(e)
Disconnect impervious surfaces by directing runoff to pervious
areas.
(f)
Minimize soil disturbance and compaction.
(3)
Incorporate the techniques for low-impact development practices described
in the Pennsylvania Stormwater Best Management Practices Manual (BMP
Manual).
C.
Stormwater flows onto adjacent property shall not be created, increased,
decreased, relocated, or otherwise altered without the written notification
of the adjacent property owner(s) by the developer. Copies of all
such notifications shall be included in the SWM site plan submission.
D.
For all regulated activities where erosion and sediment control is
required in accordance with Title 25 of the Pennsylvania Code and
the Clean Streams Law, 35 P.S. § 691.1 et seq., the SWM site
plan shall include the required erosion and sedimentation control
measures. Necessary E&S BMPs shall be designed in accordance with
the Erosion and Sediment Pollution Control Program Manual (E&S
Manual) 2, No. 363-2134-008 (April 15, 2000), as amended and updated.
Approval of the SWM site plan by the Township shall be conditioned
on the applicant obtaining erosion and sedimentation control approval
from the appropriate agency(ies), when applicable.
E.
For all regulated activities where NPDES permitting is required in
accordance with the Clean Water Act (33 U.S.C. § 1251 et
seq. [1972], as amended), the SWM site plan shall include the information
required in the applicant's NPDES permit application. Approval of
the SWM site plan by the Township shall be conditioned on the applicant
obtaining NPDES permit approval from the appropriate agency(ies),
when applicable.
G.
Special management areas. SWM site plans involving regulated activities
within special management areas shall be prepared in a manner consistent
with the guidance provided in Chapter 7 of the BMP Manual. The SWM
site plan submission shall include design details for SWM BMPs within
said special management area.
H.
An SWM site plan may propose that stormwater related to the proposed
regulated activities be accommodated by existing stormwater management
facilities on adjoining or nearby properties provided that the SWM
site plan documents the following.
(1)
The use of the stormwater management facilities located on said adjoining
or nearby property is approved, in writing, by the owner of the property.
(2)
The stormwater management facilities located on said adjoining or
nearby property are designed in a manner that can accommodate the
stormwater management needs of the regulated activity in a manner
consistent with all requirements of this chapter. The SWM site plan
shall include all documentation necessary for the Township to confirm
such compliance.
I.
The design storm volumes to be used in the analysis of peak rates
of discharge shall be obtained from the Precipitation-Frequency Atlas
of the United States, Atlas 14, Volume 2, Version 3.0, as amended
and updated, 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/.
J.
SWM site plans, once approved by the Township, shall remain on site
throughout the duration of the regulated activity and be available
for review as may be necessary by representatives of the Township.
K.
The design of all facilities over karst shall include an evaluation
of measures to minimize adverse effects.
L.
The Township may, after consultation with DEP, 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, 35 P.S. § 691.1 et seq. The municipality shall
maintain a record of consultations with DEP pursuant to this subsection.
A.
A property owner or developer of any regulated activity that meets
the following exemption criteria is, upon approval from the Township,
exempt from the formal SWM plan submission requirements of this chapter
as specified herein. However, the property owner or developer shall
be subject to all other requirements of this chapter other than the
formal SWM plan submission requirements for which an exemption or
exemptions have been authorized. The criteria for exemption in this
section apply to the total development proposed, including instances
in which the development is proposed to take place in phases. The
date of enactment of this chapter shall be the starting point from
which future development and the respective exemption criteria shall
be cumulatively considered and regulated.
(1)
Regulated activities that involve (1) equal to or less then 500 square
feet of impervious surface for lots having an area of 20,000 square
feet or less; or (2) equal to or less than 1,000 square feet of impervious
surface for lots having an area of greater than 20,000 square feet
may be exempted from the peak rate control, volume control and the
SWM site plan preparation and submission requirements of this chapter.
The applicant shall complete the Municipal Stormwater Management Worksheet
from the Stormwater Management Design Assistance Manual and file said
Worksheet with the Township.
(2)
Regulated activities that involve greater than 1,000 square feet
and equal to or less than 10,000 square feet of impervious area, and
where the all the proposed impervious area can be entirely disconnected,
may be exempted from the peak rate control, volume control, and the
SWM site plan preparation and submission requirements of this chapter.
The applicant shall complete the Stormwater Management Worksheets
from the Stormwater Management Design Assistance Manual and file said
Worksheets with the Township.
(3)
Regulated activities that involve greater than 1,000 square feet and equal to or less than 5,000 square feet of impervious area may be exempted from the peak rate control and volume control preparation and submission requirements of this chapter. A minor stormwater site plan, as detailed in the Stormwater Management Design Assistance Manual, shall be submitted to the Township instead of the submission of a full SWM site plan in accordance with Article IV of this chapter.
(4)
Agricultural activities shall be exempt from the rate control, volume control and SWM site plan preparation and submission requirements of this chapter, provided the agricultural activities are performed in accordance with the requirements of 25 Pa. Code Chapter 102. Further, such activities shall not be subject to the exemption approval process of § 149-15B of this chapter.
(5)
Forest management and timber operations are exempted from the rate
control, volume control and SWM site plan preparation and submission
requirements of this chapter provided the forest management and timber
operations are performed in accordance with the requirements of 25
Pa. Code Chapter 102.
(6)
Regulated activities involving domestic gardening for single-family consumption shall be exempted from volume control, rate control, and SWM site plan preparation and submission requirements of this chapter, and shall not be subject to the exemption approval process of § 149-15B of this chapter.
(7)
In-kind repair, in-kind replacement, and maintenance of existing surfaces, and structures shall be exempted from volume control, rate control, and SWM site plan preparation and submission requirements of this chapter, and shall not be subject to the exemption approval process of § 149-15B of this chapter.
B.
Authorization of exemptions. The Township shall determine, in accordance
with the following requirements and process, whether a proposed regulated
activity may be exempted from any of the requirements of this chapter.
(1)
The property owner or developer proposing the regulated activity shall submit, in writing on a form supplied by the Township, a request for said proposed regulated activity to be exempted from allowable requirements of this chapter pursuant to Subsection A. The written request shall identify the project and shall indicate the specific exemption criteria, as listed in § 149-15A, that apply to the project, and shall be submitted in accordance with the Stormwater Management Worksheets from the Stormwater Management Design Assistance Manual.
(2)
Within 45 days of the receipt of the exemption request form, the
Township or its designee shall either approve or deny the exemption
request. If the exemption request is denied, the Township or its designee
shall direct the property owner or developer to submit the information
required to demonstrate that the proposed regulated activity complies
with the requirements of this chapter or meets the exemption criteria.
(3)
Exemption request approval shall be at the discretion of the Township,
and shall be subject to the following:
(a)
The Township may deny any exemption request or suspend or revoke
any approved exemption request at any time for any project where the
Township believes that the proposed regulated activity poses a threat
to public health, safety, property, or the environment.
(b)
Approval of an exemption request does not relieve the property
owner or developer from other applicable requirements of this chapter
or of other Township ordinance or regulations.
(c)
The Township reserves the right to deny an exemption request
if a drainage problem is known or identified by the Township to exist
or is expected to exist downstream from the proposed regulated activity.
A.
Impervious area.
(1)
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 phases.
(2)
For development taking place in phases, the total proposed impervious
area within the SWM site plan must be used in determining conformance
with this chapter.
(3)
For projects that add impervious area to a parcel, the total impervious area on the parcel is subject to the requirements of this chapter; except that the volume controls in § 149-17 and the peak rate controls of § 149-18 do not need to be retrofitted to existing impervious areas that are not being altered by the proposed regulated activity.
(4)
For new residential subdivisions, 5,000 square feet of impervious
area shall be used for each residential lot when preparing the stormwater
management plan for the subdivision, unless the Township requires
or allows that a different amount of impervious area be used. If the
impervious area, during development, should exceed 5,000 square feet,
the property owner will be required to submit a stormwater management
plan showing how the additional impervious area will be controlled.
B.
Normally dry, open-top storage facilities, designed as such, shall
completely drain both the volume control and rate control capacities
over a period of time not less than 24 hours and not more than 72
hours from the end of the design storm. However, any designed infiltration
volume at such facilities is exempt from the minimum twenty-four-hour
standard, i.e., may infiltrate in a shorter period of time, so long
as none of the stormwater intended for infiltration is discharged
into the surface waters of the commonwealth.
C.
Infiltration BMPs shall 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 chapter.
The low impact development practices provided in the BMP Manual shall be utilized for all regulated activities. Water volume controls shall be implemented using the Design Storm Method in § 149-17A or the Simplified Method in § 149-17B. For regulated activity involving less than one acre of impervious coverage that does not require hydrologic routing to design the stormwater facilities, 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/or other factors. The Design Storm Method in § 149-17A shall be used for all regulated activity involving greater than one acre of impervious coverage.
A.
The Design Storm Method (CG-1 in the BMP Manual) may be used for
any size of regulated activity. This method requires detailed modeling
to achieve the following standards.
(1)
The post-development total runoff volume shall not increase 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) is independent of
site conditions and may be used for projects involving regulated activities
proposing equal to or less than one acre of impervious coverage and
that do not require design of stormwater storage facilities. When
the Simplified Method is used to address stormwater management needs
of new impervious surfaces, the following design standards shall be
achieved:
(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 and shall not be
released into the surface waters of the commonwealth. Removal options
for the first one inch of runoff include, but are not necessarily
limited to, reuse and infiltration.
(3)
Infiltration facilities shall be designed to accommodate infiltration of as much of the permanently removed runoff as site conditions will allow. If the soils within the project area do not allow for infiltration of the entire first one inch of runoff from new impervious surfaces, other forms of runoff volume control shall be used to achieve the required removal volume. Such measures may include, but are not limited to, vegetated roofs, biorention, and capture-and-reuse systems. In addition, the infiltration alternative authorized in § 149-17C may be employed.
C.
Infiltration alternative. Where infiltration is not possible due to soil characteristics or is not desirable given other characteristics, water quality control may be proposed as an alternative to strict adherence to the volume control standards of § 149-17 of this chapter. Where water quality control is proposed, the following standards shall be achieved:
(1)
At a minimum, the following documentation shall be provided to justify
the proposal to reduce the infiltration requirements:
(a)
Description of and justification for field infiltration/permeability
testing with respect to the type of test and test locations.
(b)
An interpretive narrative describing existing soils of the site
and their structure as these relate to the interaction between soils
and water characteristics of the site. In addition to providing soil
and soil profile descriptions, this narrative shall identify depth
to seasonal water tables and depth to bedrock and provide a description
of all subsurface elements (restrictive layers, geology, etc.) that
influence the direction and rate of subsurface water movement.
(c)
A qualitative assessment of the site's contribution to annual
aquifer recharge shall be made, along with the identification of any
restrictions or limitations associated with the use of designed infiltration
facilities.
(d)
The provided documentation must be signed and sealed by a professional
engineer or geologist.
(2)
Water quality BMPs shall be implemented on all permanent stormwater
discharges from the proposed project site to achieve pollutant removal
efficiencies in accordance with the Table 147-17.
|
Table 147-17. Required Pollutant Removal Efficiencies for Infiltration
Alternatives
| ||
|---|---|---|
|
Pollutant Load
|
Units
|
Required Removal Efficiency
(%)
|
|
Total suspended solids (TSS)
|
Pounds
|
85%
|
|
Total phosphorus (TP)
|
Pounds
|
85%
|
|
Total nitrate (NO3)
|
Pounds
|
50%
|
(3)
Design guidance from the most current version of the Pennsylvania
Stormwater Best Management Practices Manual, or equivalent resource
as precoordinated with the Township shall be consulted when choosing
design criteria for water quality BMPs.
A.
Post-development discharge rates shall not exceed the pre-development
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 pre-development 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.
B.
For computation of pre-development peak discharge rates, 20% of existing
impervious areas, when present, shall be considered meadow.
Where an applicant proposes to utilize riparian buffers as the
means to meet the requirements of this chapter, said riparian buffers
shall be established and/or maintained in accordance with the BMP
Manual or the publication Riparian Forest Buffer Guidance, published
November 2010 by the Pennsylvania Department of Environmental Protection,
and as may be amended or updated.
A.
Any drain or conveyance, whether on the surface or subsurface, that
allows any non-stormwater discharge, including sewage, process wastewater,
and wash water, to enter the waters of the commonwealth is prohibited.
B.
No person shall allow, or cause to allow, discharges into surface waters of the commonwealth which are not composed entirely of stormwater, except (1) as provided in Subsection C below and (2) discharges allowed under a state or federal permit.
C.
The following discharges are authorized unless they are determined
to be significant contributors to pollution to the waters of the commonwealth:
(1)
Discharges from firefighting activities.
(2)
Potable water sources, including water line flushing.
(3)
Irrigation drainage.
(4)
Air-conditioning condensate.
(5)
Springs.
(6)
Water from crawl space pumps.
(7)
Pavement wash waters where spills or leaks of toxic or hazardous
materials have not occurred (unless all spill material has been removed)
and where detergents are not used.
(8)
Diverted stream flows.
(9)
Flows from riparian habitats and wetlands.
(10)
Uncontaminated water from foundations or from footing drains.
(11)
Lawn watering.
(12)
Dechlorinated swimming pool discharges.
(13)
Uncontaminated groundwater.
(14)
Water from individual residential car washing.
(15)
Routine external building wash-down (which does not use detergents
or other compounds).
(16)
Water discharged in well testing for potable water supplies.
Roof drains, sump pumps, and footer drains should discharge
to infiltration or vegetative BMPs and, to the maximum extent practicable,
satisfy the criteria for DIAs. Discharges of each should be conveyed
in such a manner as to not cause water problems for adjoining property
owners. Roof drains, sump pumps and footer drains shall not discharge
to roadways, curblines, or storm sewer systems without written approval
of the Township.
No person shall modify, remove, fill, landscape, or alter any
SWM BMPs, facilities, areas, or structures in a manner, without the
written approval of the Township, with the exception of necessary
maintenance activities such as mowing.
