[Amended 9-11-2000 by Ord. No. 7-2000; 6-25-2001 by Ord. No.
4-2001; 4-9-2007 by Ord. No. 6-2007]
The objectives of this article are as follows:
A.
To regulate stormwater runoff, erosion and sedimentation,
to protect and preserve surface waters and groundwaters of the Township
and to protect the health, safety and general welfare of Township
residents; specifically, to prevent significant increase in surface
runoff volumes, predevelopment to postdevelopment, that contribute
to worsening flooding downstream in the Township's watersheds, enlarging
floodplains, eroding streambanks and creating other flood-related
health-welfare-property losses and to work to reduce runoff volumes
to natural levels.
B.
To maintain or improve year-round flows and water
quality in all streams and watercourses of the Township, specifically
first-order and other especially sensitive streams, to work to restore
natural hydrologic regimes wherever possible throughout the stream
system, and to protect the flora and fauna that depend on the natural
hydrologic regimes of the Township.
C.
To control runoff, erosion and sedimentation through
measures that are on site or situated as close as possible to where
stormwater falls on the land.
D.
To maximize recharge of groundwater and encourage
storage of rainfall to sustain groundwater supplies and stream flows;
in particular, to maintain the predevelopment volume of groundwater
recharge in order to protect the groundwater table, critical stream
baseflow and discharges to natural wetlands.
E.
To limit the use of stormwater structures which will
present maintenance problems and to encourage the design of structures
which will permit multiple uses, such as recreation.
F.
To ensure that the short-term and long-term financial
obligations of the Township for stormwater management programs, facilities
and corrective actions are minimized.
G.
To minimize nonpoint-source pollutant loadings to
groundwater and surface waters generally throughout the Township.
H.
To implement an illicit discharge detection and elimination program
that addresses nonstormwater discharges.
[Added 12-16-2013 by Ord. No. 5-2013]
I.
To provide standards to meet certain NPDES stormwater permit requirements.
[Added 12-16-2013 by Ord. No. 5-2013]
J.
To meet federal and state regulations that require the Township to
implement a program of stormwater controls, specifically to obtain
a permit and comply with its provisions for stormwater discharges
from its separate storm sewer system under the National Pollutant
Discharge Elimination System (NPDES).
[Added 12-16-2013 by Ord. No. 5-2013]
K.
To meet legal water quality requirements under state law, including regulations at 25 Pa. Code Chapter 93, to protect, maintain, reclaim and restore the existing and designated uses of the waters of the commonwealth.
[Added 12-16-2013 by Ord. No. 5-2013]
L.
Fulfill the purpose and requirements of Pennsylvania Act 167 (Act
167, Section 3):[1]
|
"(1)
|
Encourage planning and management of storm water runoff in each
watershed which is consistent with sound water and land use practices.
| |
|
(2)
|
Authorize a comprehensive program of stormwater management designated
to preserve and restore the flood carrying capacity of Commonwealth
streams; to preserve to the maximum extent practicable natural storm
water runoff regimes and natural course, current and cross-section
of water of the Commonwealth; and to protect and conserve ground waters
and ground-water recharge areas.
| |
|
(3)
|
Encourage local administration and management of storm water
consistent with the Commonwealth's duty as trustee of natural resources
and the people's constitutional right to the preservation of natural,
economic, scenic, aesthetic, recreational and historic values of the
environment."
|
[1]
Editor's Note: See 32 P.S. § 680.1 et seq.
M.
Reduce scour, erosion, and sedimentation of stream channels.
[Added 12-12-2022 by Ord.
No. 3-2022]
N.
Provide stormwater management performance standards and design criteria
on a watershed basis.
[Added 12-12-2022 by Ord.
No. 3-2022]
A.
The Township is empowered to regulate land use activities
that affect runoff, surface water and groundwater quality and quantity
by the authority of the Act of October 4, 1978, 32 P.S. § 680.1
et seq., as amended, P.L. 864 (Act 167), the Stormwater Management
Act (hereinafter referred to as "the Act") and the Water Resources
Management Act of 2002, as amended; the Second Class Township Code,
53 P.S. § 65101 et seq., and the Pennsylvania Municipal
Planning Code, Act 247, as amended.[1]
[Amended 12-16-2013 by Ord. No. 5-2013]
(1)
All regulated activities as defined in this article including, but
not limited to, new development, redevelopment, and earth disturbance
activities that are located within the Township shall be subject to
regulation by this article.
(2)
Notwithstanding any provision(s) of this article, including exemptions,
any landowner or any person engaged in a regulated activity, including
but not limited to the alteration or development of land, which may
affect stormwater runoff characteristics, shall implement such measures
as are reasonably necessary to prevent injury to health, safety, or
other property. Such measures also shall include actions as are required
to manage the rate, volume, direction, and quality of resulting stormwater
runoff in a manner which otherwise adequately protects health, property,
and water quality of waters of the commonwealth.
(3)
Any regulated activity (including but not limited to new development,
redevelopment, or earth disturbance) that is to take place incrementally
or in phases, or occurs in sequential projects on the same parcel
or property, shall be subject to regulation by this article if the
regulated impervious surface or earth disturbance exceeds the corresponding
threshold for exemption. The date of adoption of this provision (December
16, 2013, last ordinance update) shall be the starting point from
which to consider tracts as parent tracts relative to future subdivisions,
and from which impervious surface and earth disturbance computations
shall be cumulatively considered.
[Amended 12-12-2022 by Ord. No. 3-2022]
[1]
Editor's Note: See 53 P.S. § 10101
et seq.
B.
The management of stormwater on the site, both during
and upon completion of the disturbances associated with the proposed
subdivision or land development, shall be accomplished in accordance
with the standards and criteria of this article. The design of any
temporary or permanent facilities and structures and the utilization
of any natural drainage systems shall be in full compliance with this
article and the interpretations of the Township Engineer.
C.
At the time of application for a building permit for
any approved lot created by a subdivision and/or improved as a land
development project, issuance of the permit shall be conditioned upon
adherence to the terms of this article.
D.
Permits and approvals issued pursuant to this article
do not relieve the applicant of responsibility for securing other
required permits for work to be done which is regulated by any other
applicable code, rule, act or ordinance. This article shall not preclude
the inclusion in such other permit of more stringent requirements
concerning regulation of stormwater and erosion.
E.
Applicants shall refer to the Pennsylvania Stormwater
Best Management Practices Manual (December 2006 and subsequent revisions)
to design stormwater management facilities most appropriate to individual
site conditions. Objectives for design, in order of Township preference,
are: to recharge runoff at its source to the maximum extent possible;
achieve water quality improvement during any conveyance; and provide
for storage as needed. Applicants shall examine design alternatives
according to this hierarchy, viewing them in a series. In addition,
applicants are strongly encouraged to use structural or nonstructural
best management practices (BMPs) that reduce or eliminate the need
for detention basins. If methods other than green infrastructure,
low-impact design (LID), and conservation design (CD) methods are
proposed to achieve the volume and rate controls required under this
article, the SWM site plan must include a detailed justification demonstrating
that the use of LID, green infrastructure, and CD are not practicable.
[Amended 7-18-2011 by Ord. No. 7-2011; 12-12-2022 by Ord. No. 3-2022]
F.
For any regulated activity, unless exempt per the provisions of § 73-36G:
[Added 12-16-2013 by Ord. No. 5-2013[2]]
(1)
Preparation and implementation of an approved SWM site plan is required.
(2)
No regulated activity shall commence until the Township issues written
approval of a SWM site plan, which demonstrates compliance with the
requirements of this article and, if required, a letter of adequacy
has been issued by the Chester County Conservation District for an
erosion and sediment control plan.
(3)
The preliminary or final approval of subdivision and/or land development
plans and the issuance of any building or occupancy permit shall not
proceed until the applicant has received written approval of a SWM
site plan from the Township.
(4)
The SWM site plan approved by the Township shall be on site throughout
the duration of the regulated activity.
(5)
A complete SWM site plan that complies with all applicable provisions
of this article shall be submitted to the Township for review and
approval, as follows:
(a)
The SWM site plan shall be coordinated with the applicable state
and federal permit process and the Township SALDO review process.
All permit approvals or letters of adequacy not yet received by the
applicant at the time of submittal of the SWM site plan to the Township
must be submitted to the Township prior to (or as a condition of)
the Township's final approval of the SWM site plan.
(b)
For projects that require SALDO approval, the SWM site plan
shall be submitted by the applicant as part of the preliminary plan
submission where applicable for the regulated activity.
(c)
For regulated activities that do not require SALDO approval,
the SWM site plan shall be submitted by the applicant for review in
accordance with instructions from the Township.
(d)
The number of copies of the SWM site plan to be submitted by
the applicant for review shall be in accordance with instructions
from the Township.
(e)
The corresponding review fee shall be submitted to the Township
simultaneously with the SWM site plan, per the Township's fee schedule.
[2]
Editor's Note: This ordinance also provided for the redesignation
of former Subsection F as Subsection G.
G.
Exemptions.
[Amended 7-18-2011 by Ord. No. 7-2011; 12-16-2013 by Ord. No.
5-2013]
(1)
An exemption from any requirement of this article shall not relieve
the applicant from implementing all other applicable requirements
of this article or from implementing such measures as are necessary
to protect public health, safety, and welfare, property and water
quality. Furthermore, an exemption shall not relieve the applicant
from complying with the requirements for state-designated special
protection waters designated by PADEP as high-quality (HQ) or exceptional-value
(EV) waters, or any other current or future state or municipal water
quality protection requirements. Finally, an exemption under this
article shall not relieve the applicant from complying with all other
applicable Township articles or regulations.
(2)
The following activities may be exempted from on-site stormwater
runoff control. An exemption shall apply only to the requirement for
on-site stormwater facilities and the preparation of a stormwater
management plan. All other stormwater management design elements,
such as a storm sewer system, road culverts, erosion and sedimentation
control, and runoff quality, shall be required. All exemption requests
must be filed with the Township Zoning Officer.
(a)
Emergency exemption: emergency maintenance work performed for
the protection of public health, safety and welfare. This exemption
is limited to repair of the existing stormwater management facility;
upgrades, additions or other improvements are not exempt. A written
description of the scope and extent of any emergency work performed
shall be submitted to the Township within two calendar days of the
commencement of the activity. A detailed plan shall be submitted no
later than 30 days following commencement of the activity. If the
Township finds that the work is not an emergency, then the work shall
cease immediately and the requirements of this article shall be addressed
as applicable.
[Amended 12-12-2022 by Ord. No. 3-2022]
(b)
Maintenance exemption: any maintenance to an existing stormwater
management facility, BMP or conveyance made in accordance with plans
and specifications approved by the Township Engineer or Township.
[Amended 12-12-2022 by Ord. No. 3-2022]
(c)
Gardening: use of land for gardening for home consumption.
(d)
Agricultural activities: agriculture when operated in accordance
with the requirements of 25 Pa. Code Chapter 102 and in accordance
with a conservation plan, nutrient management plan or erosion and
sedimentation control plan approved by the Chester County Conservation
District, including activities such as growing crops, rotating crops,
tilling of soil and grazing animals. Installation of new or expansion
of existing farmsteads, animal housing, waste storage and production
areas having impervious surfaces that result in a net increase in
impervious surface of greater than 800 square feet shall be subject
to the provisions of this article.
[1]
Exemptions for specific activities.
[Added 1-27-2020 by Ord. No. 1-2020]
[a]
Agricultural-related activities: high tunnels, provided a zoning permit is obtained pursuant to § 139-113, and if:
[i]
The high tunnel or its flooring does not result in an impervious
area exceeding the coverage limits of the zoning district in which
the structure is located or result in an impervious area exceeding
25% of all structures located on the owner' s total contiguous land
area; and
[ii]
The high tunnel meets one of the following:
[A]
The high tunnel is located at least 100 feet from any perennial
stream or watercourse, public road or neighboring property line;
[B]
The high tunnel is located at least 35 feet from any perennial
stream or watercourse, public road, or neighboring property line and
located on land with a slope not greater than 7%;
[C]
The high tunnel is supported with a buffer or diversion system
that does not directly drain into a stream or other watercourse by
managing stormwater runoff in a manner consistent with the requirements
of this chapter.
(e)
Forest management: forest management operations which are consistent with a sound forest management plan as approved by the Township Zoning Officer and which follow the Pennsylvania Department of Environmental Protection's management practices contained in its publication "Soil Erosion and Sedimentation Control Guidelines for Forestry" (as amended or replaced by subsequent guidance). Such operations are required to have an erosion and sedimentation control plan, which meets the requirements of 25 Pa. Code Chapter 102 and meets the erosion and sediment control standards of Chapter 73.
(f)
Improvement-related exemption: The cumulative total square feet
of all regulated impervious surfaces must not exceed the impervious
surface standards of the applicable zoning district. Stormwater management
facilities will not be required for any net increase of impervious
surface up to 800 square feet.
[Amended 12-12-2022 by Ord. No. 3-2022[
(g)
Existing landscaping: use of land for maintenance, replacement
or enhancement of existing landscaping.
(h)
Maintenance of existing gravel and paved surfaces: Replacement of existing gravel and paved surfaces shall meet the erosion and sediment control requirements of 25 Pa. Code Chapter 102 and this Chapter 73. Resurfacing of existing gravel and paved surfaces is exempt from the requirements of this chapter. Construction of new or additional impervious surfaces shall comply with all requirements of this chapter.
{Amended 12-12-2022 by Ord. No. 3-2022]
(i)
Township roadway shoulder improvements: Shoulder improvements
conducted within the existing roadway cross-section of Township-owned
roadways, unless an NPDES permit is required, in which case the proposed
work must comply with all requirements of this chapter.
(j)
In-place replacement of residential dwelling unit: the replacement
in the exact footprint of an existing one- or two-family dwelling
unit.
(k)
In-place replacement, repair, or maintenance of residential
impervious surfaces: the replacement of existing residential patios,
decks, driveways, pools, garages, and/or sidewalks that are accessory
to an existing one- or two-family dwelling unit in the exact footprint
of the existing impervious surface.
H.
Waivers.
[Added 12-16-2013 by Ord. No. 5-2013]
(1)
General. The requirements of this article are essential and shall be strictly adhered to. For any regulated activity where, after a close evaluation of alternative site designs, it proves to be impracticable to meet any one or more of the mandatory minimum standards of this article on the site, the Township may approve measures other than those in this article, subject to Subsection G(2).
(2)
PADEP approval required. No waiver or modification of any regulated
stormwater activity involving earth disturbance greater than or equal
to one acre may be granted by the Municipality unless that action
is approved in advance by PADEP or the Chester County Conservation
District.
[Amended 12-12-2022 by Ord. No. 3-2022]
I.
Erroneous permit. Any permit or authorization issued or approved
based on false, misleading or erroneous information provided by an
applicant is void without the necessity of any proceedings for revocation.
Any work undertaken or use established pursuant to such permit or
other authorization is unlawful. No action may be taken by a board,
agency, or employee of the Township purporting to validate such a
violation.
[Added 12-16-2013 by Ord. No. 5-2013; amended 12-12-2022 by Ord. No.
3-2022]
A.
General requirements.
(1)
Applicants proposing regulated activities in the Township which do not fall under the exemption criteria shown in § 73-36F shall submit a conservation plan consistent with this article and the respective stormwater management plan to the Township for review. The stormwater management criteria of this article shall apply to the total proposed development even if development is to take place in stages.
(2)
The applicant is required to find practicable alternatives
to the surface discharge of stormwater, the creation of impervious
surfaces, and the degradation of waters of the commonwealth and must
maintain as much as possible the natural hydrologic regime.
(3)
The drainage plan must be designed consistent with the sequencing provisions of § 73-37C to ensure maintenance of the natural hydrologic regime, to promote groundwater recharge, and to protect groundwater and surface water quality and quantity. The drainage plan designer must proceed sequentially in accordance with § 73-37C of this article.
(4)
Stormwater drainage systems shall be designed in order
to permit unimpeded flow along natural watercourses, except as modified
by stormwater management facilities or open channels consistent with
this article.
(5)
Discharges to adjacent or downgradient properties.
[Amended 7-18-2011 by Ord. No. 7-2011; 12-16-2013 by Ord. No.
5-2013; 9-8-2014 by Ord. No. 3-2014]
(a)
Existing points of concentrated drainage. Existing points of
concentrated drainage (peak rate discharges up to and including the
one-hundred-year storm) that discharge onto adjacent property(ies)
or downgradient property(ies), including diffuse drainage discharge,
shall not be altered in any manner without written permission from
the Township and affected landowners, and, as determined by the Township,
an easement and agreement with such affected landowner(s) for conveyance
of discharges onto or through their property(ies). Such discharge
shall be subject to any applicable discharge criteria specified in
this article.
(b)
Proposed new discharges of stormwater. Proposed new discharges
of stormwater from any frequency rainfall event, up to and including
the one-hundred-year, twenty-four-hour storm event, that may potentially
cause harm prior to reaching an existing conveyance system or a natural
watercourse, or by reducing flow to wetlands or other sensitive habitats,
shall be designed to avoid erosion, flooding or other damage to the
properties through which it is being conveyed. For any activity that
requires a building permit, regardless of square footage, applicants
must provide proof that written notification has been made to adjacent
downgradient property owner(s) that an application has been submitted
to the Township requesting approval for a permit that may discharge
stormwater onto their property; furthermore, applicants shall be required
to receive written permission from, and, as determined by the Township,
an easement and agreement with the affected landowner(s) for conveyance
of discharges onto or through their property(ies).
(6)
Areas of existing diffused drainage discharge, whether
proposed to be concentrated or maintained as diffused drainage areas,
shall be subject to any applicable discharge criteria in the general
direction of existing discharge, except as otherwise provided by this
article. If diffused drainage discharge 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 impacts will result from the concentrated discharge.
(7)
Where a development site is traversed by an existing watercourse, drainage easements shall be provided conforming to the line of such streams. The terms of the easement shall conform to the RBA buffer requirements contained in Article XII of this chapter.
(8)
Any stormwater management facilities regulated by
this article that would be located in or adjacent to waters of the
commonwealth or delineated wetlands shall be subject to approval by
DEP through the joint permit application or the environmental assessment
approval process, or where deemed appropriate, by the DEP general
permit process. When there is a question as to 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 DEP.
(9)
Minimization of impervious surfaces and infiltration
of runoff through seepage beds, infiltration trenches, etc., is encouraged
where soil conditions permit in order to reduce the size or eliminate
the need for detention facilities or other structural BMPs.
(10)
All regulated activities within the Township
shall be designed, implemented, operated, and maintained to meet the
purposes of this article, through these two elements:
(11)
No regulated earth disturbance activities within
the Township shall commence until the requirements of this article
are met.
(13)
Operations and maintenance of permanent stormwater BMPs shall be addressed as required by § 73-43.
(14)
All BMPs used to meet the requirements of this
article shall conform to the state water quality and stormwater management
requirements and any more stringent requirements as set forth by the
Township.
[Amended 12-16-2013 by Ord. No. 5-2013]
(15)
Techniques described in Appendix D (Conservation
Design and Low Impact Development Site Design)[1] of this chapter shall be considered because they reduce
the costs of complying with the requirements of this article, better
manage stormwater, protect the environment, and meet Pennsylvania
water quality requirements.
[1]
Editor's Note: Appendix D is included as an attachment to this chapter.
(16)
In selecting the appropriate BMPs or combinations
thereof, the applicant shall consider the following:
(a)
Total contributing area.
(b)
Permeability and infiltration rate of the site's
soils.
(c)
Slope and depth to bedrock.
(d)
Seasonal high water table.
(e)
Proximity to building foundations and wellheads.
(f)
Erodibility of soils.
(g)
Land availability and configuration of the topography.
(h)
Peak discharge and required volume control.
(i)
Stream bank erosion.
(j)
Efficiency of the BMPs to mitigate potential
water quality problems.
(k)
The volume of runoff that will be effectively
treated.
(l)
The nature of the pollutant being removed.
(m)
Maintenance requirements.
(n)
Creation/protection of aquatic and wildlife
habitat.
(o)
Recreational value.
(17)
The applicant may meet the stormwater management
criteria through off-site stormwater management measures as long as
the proposed measures are in the same subwatershed and the applicant
can prove that doing so will not adversely affect adjoining or downstream
properties.
(18)
To the maximum extent practicable, and unless otherwise approved
by the Township Engineer, the post-construction one-year, twenty-four-hour
storm flow shall be detained for a minimum of 24 hours and a maximum
not to exceed 72 hours from a point in time when the maximum volume
of water from the one-year, twenty-four-hour storm is stored in a
proposed BMP (i.e., when the maximum water surface elevation is achieved
in the facility). Release of water can begin at the start of the storm
(i.e., the invert of the orifice is at the invert of the proposed
BMP).
[Added 12-16-2013 by Ord. No. 5-2013]
(19)
All proposed stormwater facilities shall make use of measures
to extend the flow path and increase the travel time of flows in the
facility.
[Added 12-16-2013 by Ord. No. 5-2013]
(20)
Only the area of the proposed regulated activity shall be subject
to the peak flow rate control standards of this article. Undisturbed
areas for which the discharge point has not changed are not subject
to the peak flow rate control standards.
[Added 12-16-2013 by Ord. No. 5-2013]
(21)
Areas located outside of the site (i.e., areas outside of the
regulated activity) that drain through a proposed site are not subject
to peak flow rate control requirements. Drainage facilities located
on the site shall be designed to safely convey flows from outside
of the site through the site.
[Added 12-16-2013 by Ord. No. 5-2013]
(22)
The effect of structural and nonstructural stormwater management
practices implemented as part of the overall site design may be taken
into consideration when calculating total storage volume and peak
flow rates.
[Added 12-16-2013 by Ord. No. 5-2013]
B.
Permit requirements by other governmental agencies.
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:
(1)
All regulated earth disturbance activities subject
to permit requirements by DEP under regulations at 25 Pennsylvania
Code Chapter 102.
(2)
Work within natural drainageways subject to permit by DEP under 25 Pennsylvania Code Chapter 105.
(3)
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 Pennsylvania Code Chapter 105.
(4)
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.
C.
Site design process (conservation design, low-impact development
practices and sequencing to minimize stormwater impacts).
[Amended 12-16-2013 by Ord. No. 5-2013]
(1)
General approach. The applicant shall design the site to minimize
the disturbances to land, site hydrology, and natural resources, and
to maintain the natural hydrologic regime, drainage patterns and flow
conditions. The applicant shall demonstrate in its SWM site plan that
the design sequence, objectives and techniques described below were
applied to the maximum extent practicable in the site design of the
regulated activity while complying with all other requirements of
this article. The site design shall:
(a)
First, identify and delineate all existing natural resources
and natural and man-made hydrologic features located within the site,
or which receive discharge from or may be impacted by the proposed
regulated activity.
(b)
Second, provide a prioritized listing of these resources and
features to identify those to be incorporated into the site design
in a manner that provides protection from any disturbance or impact
from the proposed regulated activity; those to be protected from further
disturbance or impact but for which the proposed regulated activity
will provide improvement to existing conditions; those that can be
incorporated into and utilized as components of the overall site design
in a manner that protects or improves their existing conditions while
utilizing their hydrologic function within the limits of their available
capacity (e.g., for infiltration, evapotranspiration, or reducing
pollutant loads, runoff volume or peak discharge rates, etc.) to reduce
the need for or size of constructed BMPs; and those that may be considered
for alteration, disturbance or removal.
(2)
The design of all regulated activities shall include the following
to minimize stormwater impacts.
(a)
Applicants shall find practicable alternatives,
such as those listed in Appendix D, to the surface discharge of stormwater,
the creation of impervious surfaces, and the degradation of waters
of the commonwealth and must maintain as much as possible the natural
hydrologic regime of the site.
(b)
An alternative is practicable if it is available
and capable of implementation after taking into consideration existing
technology and logistics in light of overall municipal requirements
and project purposes.
(c)
All practicable alternatives to the discharge
of stormwater are presumed to have less adverse impact on quantity
and quality of waters of the commonwealth unless otherwise demonstrated.
(3)
The applicant shall demonstrate that the regulated activities were
designed in the following sequence. The goal of the sequence is to
minimize the increases in stormwater runoff and impacts to water quality
resulting from the proposed regulated activity:
(a)
In conjunction with the preliminary plan requirements of Chapter 123, Subdivision and Land Development, prepare a conservation plan consistent with the requirements of Chapter 73, Article III, Conservation Plan Requirements. Careful consideration should be given to natural resource protection and density calculation components contained therein.
(c)
Identify site-specific existing conditions drainage areas, discharge points, recharge areas, and hydrologic soil groups conducive to infiltration (consult the Soil Use Guide, § 73-40).
(d)
Prepare a draft project layout or sketch plan consistent with the resource protection standards in § 73-37C(2)(a) and respectful of § 73-37C(2)(c).
(e)
Evaluate nonstructural stormwater management
alternatives:
[1]
Minimize earth disturbance (minimum disturbance/minimum
maintenance, reduced grading and compaction, footprinting —
scale and placement of buildings).
[2]
Minimize impervious surfaces.
[3]
Break up and disconnect large impervious surfaces.
[4]
Locate infiltration and other BMPs at or as near to the source
of generation as possible, and at depths that are as shallow as possible.
[5]
For flow volumes requiring conveyance from the source of generation
to a BMP for management, give preference to open channel conveyance
techniques that provide infiltration and water quality benefits, and
landscaped-based management in common open space areas, where practicable.
(f)
Satisfy the groundwater recharge (infiltration) objective (§ 73-37D) and provide for stormwater pretreatment prior to infiltration.
(h)
Determine into what management district the site falls (§ 73-37F) and conduct an existing conditions runoff analysis.
(i)
Prepare final project design to maintain natural
drainage conditions and discharge points, to minimize earth disturbance
and impervious surfaces, and, to the maximum extent possible, to minimize
surface or point discharges.
(j)
Conduct a proposed conditions runoff analysis based on the final design that meets the management district requirements (§ 73-37F).
(k)
Manage any remaining runoff prior to discharge
through detention, bioretention, direct discharge, or other structural
control.
(4)
Water quality and volume control practices shall be selected and
designed to meet those criteria of this subsection that apply to water
quality and volume control.
D.
Groundwater recharge.
(1)
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 § 73-35 and to take advantage of utilizing any existing recharge areas.
(2)
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. If it can be physically accomplished, then the volume of runoff to be infiltrated shall be determined from § 73-37D(1) depending on demonstrated site conditions.
(3)
Infiltration BMPs shall meet the following minimum
requirements:
(a)
Infiltration BMPs intended to receive runoff
from developed areas shall be selected based on suitability of soils
and site conditions.
[1]
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.
[2]
The infiltration facility shall be capable of
completely infiltrating the recharge (infiltration) volume within
72 hours.
[Amended 12-16-2013 by Ord. No. 5-2013]
[3]
Sediment removal shall be provided prior to
infiltration.
(b)
In addition to the performance standards and
design criteria requirements of this article, the applicant shall
comply with the following water quality requirements unless otherwise
exempted by provisions of this article:
[Amended 7-18-2011 by Ord. No. 7-2011; 10-22-2012 by Ord. No.
3-2012; 12-16-2013 by Ord. No. 5-2013]
[1]
The post-construction total runoff volume shall not exceed the
predevelopment total runoff volume for all storms equal to or less
than the two-year, twenty-four-hour duration precipitation (design
storm). The water quality and runoff volume to be managed shall consist
of any runoff volume generated by the proposed regulated activity
over and above the predevelopment total runoff volume or one inch
of runoff from the total area draining to the infiltration facility,
whichever is greater, and shall be captured and permanently retained
or infiltrated on the site. Permanent retention options may include,
but are not limited to, reuse, evaporation, transpiration, and infiltration.
[Amended 9-8-2014 by Ord. No. 3-2014]
[2]
Detain the two-year, twenty-four-hour design storm runoff based
on the SCS Type II distribution. Provisions shall be made so that
the determined runoff takes a minimum of 24 hours to drain from the
facility from a point where maximum volume of water is captured (i.e.,
the maximum water surface elevation is achieved in the facility).
The design of the facility shall consider and minimize the chances
of clogging and sedimentation potential. The applicant shall utilize
infiltration facilities in lieu of extended detention where practicable.
The volume of infiltration provided for the contributing area may
be deducted from the volume requirement for extended detention, where
such is warranted and necessary.
(c)
Areas located outside of the site (i.e., areas outside of the
regulated activity) may be excluded from the calculation of the water
quality and runoff volume requirements.
[Added 12-16-2013 by Ord. No. 5-2013]
(4)
Soils.
(a)
The criteria in the Soil Use Guide (see Appendix A[2]) shall be followed in the initial design of temporary
and permanent erosion and sediment control and stormwater management
facilities. This appendix is based on an analysis of the Soil Survey
of Chester and Delaware Counties conducted by the Natural Resources
Conservation Service, and reflects the Township's intent to protect
valuable groundwater and surface water resources from pollution and
depletion and to control erosion and sedimentation.
[2]
Editor's Note: Appendix A is included at the end of this chapter.
(b)
In addition to the above, soil infiltration
tests shall be performed. The soil infiltration rate of discharge
from the infiltration area being used in the proposed design shall
be based on these measurements.
(c)
A detailed soils evaluation of the site shall be conducted by
a qualified professional and at a minimum shall address soil permeability,
depth to bedrock, and subgrade stability. The general process for
designing the infiltration BMP shall be conducted by a qualified licensed
professional and shall be consistent with the Pennsylvania BMP Manual
(as amended) (or other guidance acceptable to the Township Engineer)
and in general shall:
[Amended 12-16-2013 by Ord. No. 5-2013[3]]
[1]
Analyze hydrologic soil groups as well as natural and man-made
features within the site to determine general areas of suitability
for infiltration practices. In areas where development on fill material
is under consideration, 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 other
hydraulic conductivity tests (at the elevation of the proposed infiltration
surface) to determine the appropriate hydraulic conductivity rate.
Standard septic/sewage percolation tests are not acceptable for design
purposes.
[3]
Design the infiltration facility for the required retention
(infiltration) volume based on field-determined infiltration capacity
(and apply safety factor as per applicable design guidelines) at the
elevation of the proposed infiltration surface.
[4]
On-lot infiltration features are encouraged; however, it shall
be demonstrated to the Township Engineer that the soils are conducive
to infiltration on the identified lots.
[3]
Editor's Note: This ordinance also repealed former Subsection
D(4)(e), regarding infiltration requirements, and (f), regarding soil
infiltration tests, which immediately followed this subsection.
(5)
The infiltration requirement in HQ or EV waters shall be subject to the PA DEP's Chapter 93 Antidegradation Regulations.
(6)
An impermeable liner will be required in detention
basins where the possibility of groundwater contamination exists.
A detailed hydrogeologic investigation may be required by the Township.
(7)
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.
(8)
Infiltration facilities shall, to the maximum extent practicable,
be located to avoid introducing contaminants to groundwater:
[Added 7-18-2011 by Ord. No. 7-2011; amended 12-16-2013 by Ord. No.
5-2013]
(a)
When a hotspot is located in the area draining to a proposed
infiltration facility, an evaluation of the potential of groundwater
contamination from the proposed infiltration facility shall be performed,
including a hydrogeologic investigation (if necessary) by a qualified
licensed professional to determine what, if any, pretreatment or additional
design considerations are needed to protect groundwater quality.
(b)
When located within a wellhead protection area of a public water
supply well, infiltration practices shall be in conformance with the
applicable approved source water protection assessment or source water
protection plan.
(c)
The applicant shall provide appropriate safeguards against groundwater
contamination for land uses that may cause groundwater contamination
should there be a mishap or spill.
(9)
During site construction, all infiltration practice components shall
be protected from compaction due to heavy equipment operation or storage
of fill or construction material. Infiltration areas shall also be
protected from sedimentation. Areas that are accidentally compacted
or graded shall be remediated to restore soil composition and porosity.
Adequate documentation to this effect shall be submitted to the Township
Engineer for review. All areas designated for infiltration shall not
receive runoff until the contributory drainage area has achieved final
stabilization.
[Added 12-16-2013 by Ord. No. 5-2013]
(10)
Where sediment transport in the stormwater runoff is anticipated
to reach the infiltration system, appropriate permanent measures to
prevent or collect sediment shall be installed prior to discharge
to the infiltration system.
[Added 12-16-2013 by Ord. No. 5-2013]
(11)
All infiltration practices shall have appropriate positive overflow
controls.
[Added 12-16-2013 by Ord. No. 5-2013]
(12)
No sand, salt or other particulate matter may be applied to
a porous surface material for winter ice conditions.
[Added 12-16-2013 by Ord. No. 5-2013]
(13)
Water quality improvement shall be achieved in conjunction with
the infiltration requirements of this section. The infiltration volume
required under this section may be included as a component of the
water quality volume. If the calculated water quality and runoff volume
is greater than the volume infiltrated, then the difference between
the two volumes shall be managed for water quality and runoff volume
control through other techniques or practices but shall not be discharged
from the site.
[Added 12-16-2013 by Ord. No. 5-2013]
(14)
All infiltration practices shall:
[Added 12-12-2022 by Ord.
No. 3-2022]
(a)
Be set back at least 10 feet from all buildings and features
with subgrade elements (e.g., basements, foundation walls, etc.),
unless otherwise approved by the Municipal Engineer;
(b)
For any infiltration practice that collects runoff from shared
or multiple features and that is located within 25 feet of a building
or feature with subgrade elements (e.g., basements, foundation walls,
etc.), the bottom elevation shall be set below the elevation of the
subgrade element.
E.
Water quality requirements. The applicant shall comply
with the following water quality requirements of this article.
(1)
No regulated earth disturbance activities within the
Township shall commence until approval by the Township of a plan which
demonstrates compliance with postconstruction state water quality
requirements.
(2)
The BMPs shall be designed, implemented, and maintained
to meet state water quality requirements and any other more stringent
requirements as determined by the Township. In addition, the applicant
shall meet the state water quality requirements for exceptional value
waters and high quality waters for any discharges to such waters.
(3)
To control postconstruction 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 postconstruction stormwater discharges do not degrade the physical,
chemical, or biological characteristics of the receiving waters. The
green infrastructure and low-impact development (LID) practices provided
in the PA BMP Manual, as well as the guidance on green infrastructure,
LID and conservation design (CD) provided in Appendix D,[4] shall be utilized for all regulated activities wherever
possible. These requirements shall be in addition to state water quality
requirements for discharges to exceptional value waters and high quality
waters. As described in the DEP Comprehensive Stormwater Management
Policy (No. 392-0300-002, September 28, 2002), this may be achieved
by the following:
[Amended 12-12-2022 by Ord. No. 3-2022]
(a)
Infiltration: replication of preconstruction
stormwater infiltration conditions;
(b)
Treatment: use of water quality treatment BMPs
to ensure filtering out of the chemical and physical pollutants from
the stormwater runoff; and
(c)
Stream bank and streambed protection: management
of volume and rate of postconstruction stormwater discharges to prevent
physical degradation of receiving waters (e.g., from scouring).
[4]
Editor's Note: Appendix D is included as an attachment to this chapter.
(4)
Developed areas shall provide adequate storage and treatment facilities necessary to capture and treat stormwater runoff. The volume of infiltration computed under § 73-37D 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 is greater than the volume required to be infiltrated as described in § 73-37D, 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 is the storage capacity needed to capture and treat a portion of stormwater runoff from the developed areas of the site. To achieve this requirement, the following criterion is established:
[Added 10-22-2012 by Ord. No. 3-2012[5]]
(a)
From Control Guideline (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 postdevelopment runoff
volume and the predevelopment runoff volume. The postdevelopment total
runoff volume for all storms equal to or less than the two-year, twenty-four-hour
duration precipitation shall not be increased.
[5]
Editor's Note: This ordinance also redesignated former Subsection
E(4) as Subsection E(6).
(5)
The temperature of receiving waters shall be protected through the
use of BMPs that moderate temperature.
[Added 10-22-2012 by Ord. No. 3-2012]
(6)
If areas of riparian buffer as defined (outlined) in § 73-61 of this chapter are found to exist on site, they must be delineated on the conservation plan. Furthermore the plan must demonstrate compliance with all of the provisions set forth in Article XII of this chapter, Riparian Buffer Area (RBA) Conservation District.
(7)
Evapotranspiration may be quantified and credited towards meeting
volume requirements according to the PADEP Post Construction Stormwater
Management (PCSM) Spreadsheet and Instructions (December 2020) or
the most recent guidance from PADEP.
[Added 12-12-2022 by Ord.
No. 3-2022]
F.
Stormwater management districts.
(2)
Crum Creek Stormwater District.
[Amended 10-22-2012 by Ord. No. 3-2012]
(a)
The Crum Creek Watershed has been divided into stormwater management
districts as shown on the Management District Map in Appendix E.[6]
[1]
In addition to the watershed-specific requirements specified
in the table labeled "Peak Rate Control Standards in the Crum Creek
Watershed" below, the requirements of this article shall be implemented.
[2]
Standards for managing runoff from each subarea in the Crum
Creek Watershed for the two-, five-, ten-, twenty-five-, fifty-, and
one-hundred-year design storms are shown in the table. Development
sites located in each of the management districts must control proposed
conditions runoff rates to existing conditions runoff rates for the
design storms in accordance with the table.
|
Peak Rate Control Standards in the Crum Creek Watershed
| ||||
|---|---|---|---|---|
|
District
|
Proposed Condition
Design Storm
|
(reduce to)
|
Existing Condition
Design Storm
| |
|
A
|
2-year
|
1-year
| ||
|
5-year
|
5-year
| |||
|
10-year
|
10-year
| |||
|
25-year
|
25-year
| |||
|
50-year
|
50-year
| |||
|
100-year
|
100-year
| |||
|
B
|
2-year
|
1-year
| ||
|
5-year
|
2-year
| |||
|
10-year
|
5-year
| |||
|
25-year
|
10-year
| |||
|
50-year
|
25-year
| |||
|
100-year
|
100-year
| |||
[6]
Editor's Note: Appendix E is on file in the Township offices.
(b)
General. Proposed conditions rates of runoff from any regulated
activity shall not exceed the peak release rates of runoff from existing
conditions for the design storms specified on the Stormwater Management
District Watershed Map (Appendix E)[7] and this section.
[7]
Editor's Note: Appendix E is on file in the Township offices.
(c)
District boundaries. The boundaries of the stormwater management
districts are shown on an official map that is available for inspection
at the Township and County planning offices. A copy of the official
map at a reduced scale is included in Appendix E.[8] The exact location of the stormwater management district
boundaries as they apply to a given development site shall be determined
by mapping the boundaries using the two-foot topographic contours
(or most accurate data required) provided as part of the SWM site
plan.
[8]
Editor's Note: Appendix E is on file in the Township offices.
(d)
Sites located in more than one district or watershed. For a
proposed development site located within two or more stormwater management
district subareas, the peak discharge rate from any subarea shall
meet the management district criteria for which the discharge is located.
The natural hydrology of each respective subarea shall be maintained,
and drainage shall not be redirected from one subarea to another.
Under circumstances where the applicant shows this cannot be accomplished,
the applicant must obtain a waiver from the Township.
(e)
Off-site areas. Off-site areas that drain through a proposed
development site are not subject to release rate criteria when determining
allowable peak runoff rates. On-site drainage facilities shall be
designed to safely convey off-site flows through the development site.
(f)
Site areas. Where the site area to be impacted by a proposed
development activity differs significantly from the total site area,
only the proposed impact area utilizing stormwater management measures
shall be subject to the peak rate control standards noted above. Unimpacted
areas for which the discharge point has not changed are not subject
to the peak rate control standards.
(3)
The Ridley Creek Stormwater District. The portion
of Ridley Creek in Chester County has not had an Act 167 study completed.
At such time when an Act 167 Study has been completed for Chester
County pertinent information will be added.
(4)
The Valley Creek Stormwater District. The Act 167
Plan for the Valley Creek Watershed was adopted by Chester County
on July 30, 2010, and amended February 4, 2011. As an adopted and
approved Pennsylvania Act 167 Phase II Stormwater Plan, the Township
revised its existing stormwater management standards to reflect, as
needed, the mandatory minimum standards contained in the approved
plan. In addition, the Township considered and expanded its ordinances
to reflect several of the Plan's recommended standards.
[Amended 7-18-2011 by Ord. No. 7-2011]
G.
Permanent stormwater management design parameters.
All subdivision and land development activities involving an increase
in impervious cover shall be conducted in conformance with the following
performance standards:
(1)
After installation of impervious cover, peak rate
of runoff of the two-year and five-year, twenty-four-hour design storm
events shall not exceed the predevelopment peak rate of the one-year
storm event; the one-year, twenty-four-hour storm event shall be attenuated
for at least 24 hours (i.e., the stormwater runoff will be released
over a minimum of 24 hours). Peak discharges from the site shall not
exceed the before-construction peak discharge rate from the two-year
storm of 3.2 inches of rainfall for all storms up to a ten-year, twenty-four-hour
storm of 5.0 inches of rainfall. Peak discharges for any storms of
greater than ten-year frequency up to and including a one-hundred-year
storm shall not exceed the peak discharges from the site before development
of such storms, including:
[Amended 7-18-2011 by Ord. No. 7-2011]
(a)
A twenty-five-year, twenty-four-hour storm of
5.6 inches of rainfall.
(b)
A fifty-year, twenty-four-hour storm of 6.3
inches of rainfall.
(c)
A one-hundred-year, twenty-four-hour storm of
7.2 inches of rainfall.
(d)
The above-referenced rainfall events shall be used except as
follows (in which case the greater of the events shall be used):
[Added 12-16-2013 by Ord. No. 5-2013]
[1]
All calculations using the Soil-Cover Complex Method shall use
the appropriate design rainfall depths for the various return period
storms consistent with this article. Rainfall depths used shall be
obtained from NOAA Atlas 14 values consistent with a partial duration
series. When stormwater calculations are performed for routing procedures
or infiltration, water quality and runoff volume functions, the duration
of rainfall shall be 24 hours.
[2]
All calculations using the Rational Method shall use rainfall
intensities consistent with appropriate times-of-concentration (duration)
and storm events with rainfall intensities obtained from NOAA Atlas
14 partial duration series estimates, or the latest version of the
PennDOT Drainage Manual (PDM Publication 584). Times of concentration
shall be calculated based on the methodology recommended in the respective
model used. Times of concentration for channel and pipe flow shall
be computed using Manning's Equation.
(2)
In calculating runoff prior to development or change
in use, the following assumptions shall apply:
(a)
Woodland shall be used as the prior condition
for those portions of the site having trees of greater than six-inch
caliper DBH or where such trees existed within 18 months of application.
(b)
Meadow shall be used for all other areas.
[Amended 7-18-2011 by Ord. No. 7-2011]
(c)
For all areas that are presently covered by impervious surfaces,
predevelopment volume and peak rate calculations must assume ground
cover for at least 20% of the impervious surfaces to be meadow.
[Added 7-18-2011 by Ord. No. 7-2011]
(d)
Average antecedent moisture conditions.
(e)
Where regulated activities involve a combination of both new
development and redevelopment activities, as defined herein, apply
the redevelopment and new development stormwater standards to the
corresponding redevelopment and new development portions of the proposed
regulated activity.
[Amended 12-16-2013 by Ord. No. 5-2013]
(3)
Under certain conditions including but not limited
to water bodies listed as "impaired" by PADEP, water bodies or watersheds
with an approved total maximum daily load (TMDL), areas of known existing
flooding problems, and critical areas with sensitive resources (e.g.,
state-designated special protection waters, cold water fisheries,
unique geologic features or other groundwater recharge areas that
may be highly vulnerable to contamination, drainage areas to water
supply reservoirs, etc.), the Township, upon recommendation by the
Township Engineer, may impose the following additional restrictions
on stormwater discharges:
[Amended 12-16-2013 by Ord. No. 5-2013]
(a)
Peak discharge rates on storms in excess of
the ten-year storm may be further restricted when it can be shown
that a probable risk to downstream structures or unique natural areas
exists or that an existing flooding problem would be further aggravated.
(b)
Measures may be imposed to protect against groundwater
or surface water pollution where the type of business or the nature
of the soils underlying a runoff structure would constitute a substantial
risk of contamination.
(4)
Calculation methods.
[Amended 12-16-2013 by Ord. No. 5-2013]
(a)
All plans and designs for stormwater management facilities submitted
to the Township Engineer for approval shall determine stormwater peak
discharge and runoff by use of the Soil-Cover Complex Method as set
forth in Urban Hydrology for Small Watersheds, Technical Release No.
55, with specific attention given to antecedent moisture conditions,
flood routing and peak discharge specifications included therein and
in Hydrology National Engineering Handbook, Section 4, both by United
States Department of Agriculture, Soil Conservation Service. The Township
Engineer, however, may permit the use of the Rational Method for calculation
of runoff on land developments of five acres or less and for the design
of storm sewers; in addition, Technical Release 20 and/or HEC-1/HEC-HMS
may be used where a full hydrology computer model is desirable or
necessary.
(b)
Weighted averaging of runoff coefficients shall not be used
for manual computations or input data for water quality and runoff
volume calculations.
(5)
In order to improve the quality and general utility
of stormwater management plans, subdivision and land development and
building construction shall be planned, designed and constructed in
conformance with the following principles:
(a)
Erosion and sediment control and stormwater
management control facilities shall be incorporated into all building
site designs and the overall design of any subdivision or land development
or improvement in such ways that they may serve multiple purposes
such as wildlife areas, recreational areas, fire prevention ponds,
etc.
(b)
The natural infiltration and water resource
potentials shall guide design, construction and vegetation decisions.
Runoff in excess of natural conditions from roofs and other surfaces
which are unlikely to contain pollutants shall be recharged to the
groundwater table or stored for nonpotable water uses to the maximum
extent possible.
(c)
Existing trees and shrubs shall be preserved
and protected to the maximum extent possible.
(d)
All natural streams, channels, drainage swales
and areas of surface water concentration shall be maintained in their
existing condition except where changes can be justified on the basis
of other design standards of this article.
(6)
Design alternatives.
(a)
Pursuant to § 73-36E above, applicants shall be required to examine design alternatives in the following order of importance:
[1]
Minimize the volume of runoff that must be collected,
conveyed, treated, and released by stormwater management facilities;
[2]
Maintain the natural infiltration process and
rate, and infiltrate runoff at its source;
[3]
Remove and/or treat pollutants at the source
during conveyance;
[4]
Provide for peak flow attenuation, as needed;
and
[5]
Attenuate runoff to protect the instream channel
receiving stream.
(b)
The following general principles apply to these
design alternatives:
[1]
Applicants are directed to § 73-37C and the Conservation Design and Low Impact Development Practices contained in Appendix D[9] to achieve the objectives of the design alternatives listed
above.
[9]
Editor's Note: Appendix D is included at the end of this chapter.
[2]
Infiltration of surface water runoff at its
source shall be used as the stormwater management method of choice,
where soil and site conditions warrant. Such methods shall include
subsurface seepage pits and trenches, vegetated surface berms and
other techniques outlined in the Pennsylvania Stormwater Best Management
Practices Manual (December 2006 and subsequent revisions) according
to the following criteria:
[Amended 7-18-2011 by Ord. No. 7-2011]
[a]
In choosing methods of infiltration,
preference shall be given to a combination of surface and subsurface
infiltration methods. Applicants shall first consider minimum disturbance/minimum
maintenance techniques combined with site grading that distributes
runoff to reduce concentration. Next, applicants shall consider depression
areas combined with subsurface seepage pits, followed by other subsurface
measures, including but not limited to porous paving and perforated
pipe storage. The use of multiple infiltration facilities is encouraged
where such facilities will have less visual impact and be equally
effective handling stormwater. In order to be less intrusive, stormwater
infiltration facilities should be as shallow as possible. Infiltration
areas, regardless of the BMP used, should be level in order to promote
the broad and even infiltration pattern which existed prior to development.
Where possible, such facilities should use the natural topography
and vegetation in order to blend in with the site. Other methods of
infiltration may be used if the applicant demonstrates to the Township's
satisfaction that alternative approaches would be more effective,
more attractive and as easily maintained.
[b]
Detailed soil and geologic evaluations
shall be performed to determine the extent to which infiltration systems
can be used. The evaluation shall be performed by a qualified geologist
and/or soil scientist and, at a minimum, address soil permeability,
depth to bedrock, susceptibility to sinkhole formation and subgrade
stability.
[c]
Soil infiltration tests shall be made to an equivalent depth or elevation of the bottom of the proposed infiltration areas, as described in § 73-37D(2).
[d]
Determination of the requirements for recharge shall be based on the portions of the site that are porous prior to development and the degree to which development will reduce the permeability of the site. Permeability of the site shall be determined based on the detailed evaluations described in Subsection G(6)(b)[2][b] and [c] above. Initial determination of permeability can be based on the Soil Use Guide, as contained in Appendix A.[10] Use of BMPs to retain stormwater for groundwater recharge
should be applied to all areas where infiltration structures are recommended
or highly recommended. Areas generally not recommended may be suitable
for groundwater recharge, but conditions such as slower infiltration,
impermeable horizons, seasonal high water tables or shallow bedrock
may inhibit application of recharge practices. Areas not recommended
generally are inappropriate for infiltration facilities. A requirement
of any site analysis will be to determine the extent of different
soil types on the site and the feasibility for recharge of stormwater.
[10]
Editor's Note: Appendix A is included at the end of this chapter.
[e]
Where sediment transport is anticipated
in the stormwater runoff reaching the infiltration system, appropriate
measures to prevent or collect sediment shall be installed prior to
discharge to the infiltration system.
H.
SWM site plan submission. A complete SWM site plan that complies
with all applicable provisions of this article shall be submitted
to the Township for review and approval, as follows:
[Added 12-12-2022 by Ord.
No. 3-2022]
(1)
The SWM site plan shall be coordinated with the applicable state
and federal permit process and the Township SALDO review process.
All permit approvals or letters of adequacy not yet received by the
applicant at the time of submittal of the SWM site plan to the Township
must be submitted to the Township prior to (or as a condition of)
the Township's final approval of the SWM site plan.
(2)
For projects that require SALDO approval, the SWM site plan shall
be submitted by the applicant as part of the preliminary plan submission
where applicable for the regulated activity.
(3)
For regulated activities that do not require SALDO approval, the
SWM site plan shall be submitted by the applicant for review in accordance
with instructions from the Township.
(4)
The number of copies of the SWM site plan to be submitted by the
applicant for review shall be in accordance with instructions from
the Township.
(5)
The corresponding review fee shall be submitted to the Township simultaneously
with the SWM site plan, per the Township's fee schedule.
(6)
Any submissions to the Township that are found to be incomplete shall
not be accepted for review and shall be returned to the applicant
within 10 days, with a notification in writing of the specific manner
in which the submission is incomplete.
(7)
Financial security, per the requirements of this article, shall be
submitted to the Township prior to approval of the SWM site plan.
I.
SWM site plan review.
[Added 12-12-2022 by Ord.
No. 3-2022]
(1)
The SWM site plan shall be submitted to the Township for review by
the Township Engineer for consistency with this article and the respective
PA Act 167, Stormwater Management Plan(s).[11] The Township Engineer will review the SWM site plan for
any regulated activity, subdivision or land development, for compliance
with this article and the Township SALDO provisions not otherwise
superseded by this article.
[11]
Editor's Note: 32 P.S. § 680.1 et seq.
(2)
If applicable, the applicant shall have received a letter of adequacy
from the Conservation District or other PADEP approval for the proposed
regulated activity prior to (or as a condition of) final approval
by the Township.
(3)
The Township Engineer will notify the applicant and the Township
in writing, within 30 business days, whether the SWM site plan is
consistent with the requirements of this article. If the SWM site
plan involves a subdivision and land development plan, the notification
shall occur within the time period allowed by the MPC (as amended).
If a longer notification period is provided by other statute, regulation,
or ordinance, the applicant will be so notified by the Township.
(a)
If the Township Engineer determines that the SWM site plan is
consistent with this article, the Township Engineer shall forward
a letter of consistency to the Township, who shall then forward a
copy to the applicant.
(b)
The Township may approve the SWM site plan with conditions reasonably
defined to make the SWM site plan compliant with the terms of this
article, and, if so, shall provide the conditions for approval in
writing.
(c)
If the Township Engineer determines that the SWM site plan is
inconsistent or noncompliant with this article, the Township Engineer
will forward a letter to the Township, with a copy to the applicant
citing the reason(s) and specific article sections for the inconsistency
or noncompliance. Inconsistency or noncompliance may be due to inadequate
information to make a reasonable judgment as to compliance with this
article. Any SWM site plans that are inconsistent or noncompliant
may be revised by the applicant and resubmitted in accordance with
this article. Resubmission will commence a new municipal review and
notification time period.
(4)
The Township will not grant final approval to any proposed subdivision,
land development, or regulated activity specified in this article
if the SWM site plan has been found to be inconsistent with this article.
(5)
All required permits from PADEP shall be obtained and submitted to
the Township prior to (or as a condition of) final approval of any
proposed subdivision, land development, or other regulated activity
by the Township.
(6)
No building permits for any regulated activity will be approved by
the Township if the SWM site plan has been found to be inconsistent
with this article, as determined by the Township Engineer. All required
permits from PADEP shall be obtained prior to issuance of a building
permit.
(7)
The Township's approval of a SWM site plan shall be valid for
a period not to exceed five years commencing on the date that the
Township approved the SWM site plan. If stormwater management facilities
included in the approved SWM site plan have not been constructed,
or, if constructed, as-built plans of these facilities have not been
approved within this five-year time period, then the applicant may
seek reinstatement of approval of the expired SWM site plan. If the
Township determines that the expired SWM site plan is consistent and
compliant with current regulations and requirements, then the expired
SWM site plan will be reinstated; otherwise, it will be rejected.
The applicant will be prohibited from conducting any regulated activity
until a reinstated or newly approved SWM site plan is obtained in
accordance with this article.
(8)
All or portions of the final approved SWM site plan shall be recorded
(as "recorded plans") per the instructions of the Township.
(9)
Upon completion of construction, the applicant shall be responsible
for completing final as-built plans of all BMPs, conveyances, or other
stormwater management facilities included in the approved SWM site
plan as per the requirements of this article. Applicants shall provide
to the Township final as-built plans (signed and sealed by a qualified
licensed professional) of all BMPs, conveyances, other stormwater
facilities, and related improvements shown in the final approved SWM
site plan.
(10)
For any SWM site plan that proposes to use any BMPs other than
green infrastructure, LID practices, or CD to achieve the volume and
rate controls required under this article, the Township will not approve
the SWM site plan unless it determines that green infrastructure,
LID practices, and CD are not practicable.
A.
All storm sewers shall be designed to carry, as a minimum, a flow
generated by a twenty-five-year frequency storm for its watershed.
Storm culverts conveying stream flow shall be designed to carry flow
generated by a one-hundred-year frequency storm for the stream watershed
above the culvert location. Roadway crossings or structures located
within designated floodplain areas shall be able to convey runoff
from a one-hundred-year design storm consistent with Federal Emergency
Management Agency National Flood Insurance Program floodplain management
requirements.
[Amended 12-16-2013 by Ord. No. 5-2013]
B.
All storm sewers or drainage swales shall discharge
into a stormwater management facility to control peak runoff discharge,
unless there is no increase in runoff or the increase in runoff is
compensated for by other stormwater management facilities on the site.
C.
Manholes and/or inlets shall not be spaced more than
300 feet apart for pipe sizes up to 24 inches in diameter and not
more than 450 feet apart for larger pipe sizes.
D.
On streets that contain curbing, storm sewers shall
be placed in front of the curbing. To the greatest extent possible,
storm sewers shall not be placed directly under curbing. At curbed
street intersections, storm inlets shall be placed in the tangent
section of the road.
E.
On streets that do not contain curbing, inlets shall
be placed at the center of the shoulder swale draining the street
and shall be located no closer than four feet from the edge of the
cartway.
F.
All drainage structures shall conform to the latest edition of Form
408, Pennsylvania Department of Transportation specifications. Adequate
erosion protection and energy dissipation shall be provided along
all open channels and at all points of discharge. Design methods shall
be consistent with the Federal Highway Administration Hydraulic Engineering
Circular Number 11 (Publication No. FHWA-IP-89-016, as amended) and
the PADEP Erosion and Sediment Pollution Control Program Manual (Publication
No. 363-2134-008, as amended), or other design guidance acceptable
to the Township Engineer.
[Amended 12-16-2013 by Ord. No. 5-2013]
G.
The Township shall be granted a minimum twenty-foot-wide
drainage easement over all storm sewers, drainage swales, channels,
etc., that are a component of the stormwater management system when
located within undedicated land. All permanent detention basins and/or
other stormwater management facilities providing stormwater control
for other than a single residential lot shall be located within a
defined drainage easement that will allow proper legal access and
maintenance vehicle access by Township personnel if the need arises
for such access.
H.
Where a subdivision or land development is traversed
by a watercourse, drainageway, channel or stream, there shall be provided
a drainage easement conforming substantially with the line of such
watercourse, drainageway, channel or stream. This drainage easement
shall be of such width as will be adequate to preserve the unimpeded
flow of natural drainage, for a one-hundred-year design storm and
for the purpose of widening, deepening, relocating, improving or protecting
such drainage facilities.
I.
No property owner shall obstruct or alter the flow,
location or carrying capacity of a watercourse, stream, channel or
drainage swale to the detriment of any other property owner, whether
upstream or downstream. All subdivision and/or land development plans
containing watercourses, streams, channels or drainage swales that
cross property boundaries, existing or proposed, or whose discharge
crosses such boundaries shall contain a note stating the above. The
contents of this section are not to be construed to prohibit changes
to watercourses, streams, channels or drainage swales with appropriate
permits from all applicable agencies.
J.
Applicants are encouraged to design conveyance systems
that encourage infiltration and improve water quality wherever practicable.
K.
Where drainage swales are used in lieu of or in addition to storm sewers, they shall be designed to carry the required runoff without erosion and in a manner not detrimental to the properties they cross. Drainage swales shall provide a minimum grade of 2% but shall not exceed a grade of 9%. Drainage swales used strictly for conveyance are not the same as open vegetated channels. Design standards for open vegetated channels are provided under § 73-41 of this article.
L.
Use of grassed swales or open vegetated swales in lieu of curbing to convey, infiltrate and/or treat stormwater runoff from roadways is encouraged where favorable conditions exist. Inlets shall be placed in accordance with Subsection E above.
M.
Water quality inlets. Storm drainage systems that
collect runoff from parking areas and/or loading areas exceeding 10,000
square feet of impervious coverage and discharge to stormwater management
systems, including surface or subsurface infiltration systems, shall
have a minimum of one water quality inlet per each acre of drainage
area. The purpose of water quality inlets is to remove oil, grease,
and heavy particulates or total suspended solids, hydrocarbons and
other floating substances from stormwater runoff. Methods other than
water quality inlets may be permitted if the applicant demonstrates
to the Township's satisfaction that any such alternative will be as
effective and as easily maintained. Periodic cleaning of these systems
shall be addressed in the operation and maintenance plan submitted
to the Township.
N.
Outlet structures to control stream bank erosion. Where practicable
and feasible, the minimum orifice size in the outlet structure to
the BMP shall be three inches in diameter, and a trash rack shall
be installed to prevent clogging. On sites with small drainage areas
contributing to this BMP that do not provide enough runoff volume
to allow a twenty-four-hour attenuation with the three-inch orifice,
the calculations shall be submitted showing this condition. When the
calculated orifice size is below three inches, gravel filters (or
other methods) are recommended to discharge low-flow rates subject
to the municipal engineer's satisfaction. When filters are utilized,
maintenance provisions shall be provided to ensure filters meet the
design function. All facilities shall make use of measures to extend
the flow path and increase the travel time of flows in the facility.
[Added 10-22-2012 by Ord. No. 3-2012; amended 12-16-2013 by Ord. No.
5-2013]
A.
Detention basins are generally discouraged as a stormwater management practice and should only be used as a last resort where no other management facility is practical. Detention basins typically collect and quickly release runoff from a site in a manner that is contrary to the principles, goals and standards presented within this chapter. The landscape standards of § 73-55 shall apply.
B.
Basins shall be installed prior to or concurrent with
any earthmoving or land disturbances which they will serve. The phasing
of their construction shall be noted in the narrative and on the plan.
C.
Soil requirements. Soils used for the construction
of basins should be compactable, granular soils with minimal rock
and/or silt content and are subject to approval by the Township Engineer.
D.
Energy dissipaters and/or level spreaders shall be
installed at all points where pipes or drainageways discharge.
E.
The following restrictions shall be applied to basins:
[Amended 12-12-2022 by Ord. No. 3-2022]
(1)
Exterior slopes of compacted soil shall not exceed one foot vertical for three feet horizontal and may be further reduced if the soil has unstable characteristics as noted in the Soil Use Guide (Appendix A[1]).
[1]
Editor's Note: Appendix A is included as an attachment to this chapter.
(2)
Interior slopes of the basin shall not exceed one
foot vertical in three feet horizontal except where other than earthen
materials are used for basin construction. In all such instances where
interior slopes will be steeper than one foot vertical in three feet
horizontal, the basin shall be fenced by a permanent wire fence 42
inches in height, and an access road of durable nonslip materials
shall be constructed for access into the basin, subject to the approval
of the Township Engineer.
(3)
Any stormwater basin required or regulated by this article designed to store runoff and requiring a berm or earthen embankment shall be designed to provide an emergency spillway to safely convey flow up to and including the 100-year proposed conditions. The height of embankment shall provide a minimum one foot of freeboard above the maximum pool elevation computed when the facility functions for the 100-year proposed conditions inflow. Should any BMP require a dam safety permit under 25 Pennsylvania Code Chapter 105 regulations, the facility shall be designed in accordance with and meet the regulations of 25 Pennsylvania Code Chapter 105 concerning dam safety. Chapter 105 of Title 25 of the Pennsylvania Code may require the safe conveyance of storms larger than the 100-year event.
[Added 12-12-2022 by Ord.
No. 3-2022]
F.
Outlet structures within basins which will control
peak discharge flows and distribute the flows by pipes to outlet areas
shall be constructed of concrete, steel or aluminum and shall have
childproof, nonclogging trash racks over all design openings exceeding
12 inches in diameter, except those openings designed to carry perennial
stream flows. Where principal spillways will be used to control peak
discharges in excess of the ten-year storm, the control weirs shall
be constructed of concrete of sufficient mass and structural stability
to withstand the pressures of impounded waters and outlet velocities.
Aesthetic designs that incorporate stone or other indigenous materials
are permitted, provided it can be shown to the Township's satisfaction
that such materials are structurally stable and provide long life.
G.
Inlet and outlet structures will be located, whenever possible, at maximum distances from one another. The Township Engineer may require a rock filter berm or rock-filled gabions between inlet and outlet areas when the distance is deemed insufficient for sediment trapping. The minimum required slope for the basin bottom is 2%. A level bottom is acceptable, provided that the applicant demonstrates to the Township's satisfaction that the basin bottom will be landscaped with appropriate wetland vegetation pursuant to § 73-55 and Appendix B[2] of this chapter.
[2]
Editor's Note: Appendix B is included at the end of this chapter.
H.
Emergency spillways shall be provided and shall be
designed to provide maximum protection against erosion due to overtopping.
Concrete lattice blocks, stone riprap, concrete spillways or other
suitable means of permanent stabilization shall be required when the
spillway is to be constructed within a fill area. Standards contained
in the Chester County Conservation District's Environmental Protection
Handbook and the Erosion and Sediment Control Manual shall be followed
in the design of spillways in fill that require such protection.
I.
Temporary and permanent grasses or other suitable
stabilization measures shall be established on the sides of all earthen
basins within 15 days of construction.
J.
Discharge points. The minimum distance between a proposed
basin discharge point (including the energy dissipater, etc.) and
a downstream property boundary shall in no case be less than 15 feet.
Where there is discharge onto or through adjacent properties prior
to release to a stream, designers shall demonstrate how downstream
properties are to be protected. The Municipal Engineer may require
that the setback distance be increased based upon factors such as
topography, soil conditions, the size of structures, the location
of structures, and discharge rates. A drainage easement may also be
required.
K.
Retention basins shall be designed to create a healthy ecological community with sufficient circulation of water to prevent the growth of unwanted vegetation and mosquitoes. Care should be taken to landscape retention basins in accordance with § 73-55.
L.
The retention basin shall be of sufficient size to
allow the appropriate aquatic community needed to maintain healthy
pond ecology and avoid mosquitoes capable of carrying West Nile Virus
and other diseases. The Chester County Health Department, Pennsylvania
Fish and Boat Commission, the Natural Resource Conservation Service,
the Pennsylvania Extension Service, or other qualified professional
consultant shall be consulted during the design of these facilities
in order to ensure the health of aquatic communities and minimize
the risk of creating mosquito breeding areas.
M.
The design of a retention basin shall include the
determination of the proposed site's ability to support a viable permanent
pool. The design shall take into account such factors as the available
and required rate and quality of dry weather inflow, the stormwater
inflow, seasonal and longer-term variations in groundwater table,
and impacts of potential pollutant loadings.
N.
Energy dissipaters and level spreaders. Energy dissipaters
and/or level spreaders shall be installed to prevent erosion and/or
initiate sheet flow at points where pipes or drainageways discharge
to or from basins. Energy dissipaters shall comply with criteria in
Hydraulic Engineering Circular No. 15, Design for Stable Channels
with Flexible Linings (USDOT, FHWA, 1986) or the Engineering Field
Manual for Conservation Practices (USDA, SCS, July 1984). Such facilities
shall be both functional and harmonious with the surrounding environment;
for example, native rock shall be used in constructing dissipaters
where practical.
A.
Seepage pits and trenches shall be designed to control the runoff from a one-hundred-year storm in all subdivision or land development where they are used as the only method of stormwater management. Peak discharge rates shall be designed to comply with the limits set forth in § 73-37A. Where land development and the runoff generated are considered by the Board of Supervisors to be minor, the Board, at the recommendation of the Township Engineer, may allow a lesser degree of required control if the applicant can show that there will be no detrimental effects to the environment or to adjacent property owners.
B.
A seepage pit or trench connected to a roof drain
should be located at least 10 feet from the foundation of any structure
and generally downhill in the direction of groundwater flow.
C.
The storage capacity of a stone seepage pit or trench
shall be calculated using a void ratio of 0.40. Infiltration over
the bed bottom area may be used in the calculations for the total
amount of storage provided if standard percolation testing is done
at the elevation of the bed bottom and a perk rate is established.
D.
The bottom of any seepage bed or trench must be above
any seasonal and/or permanent water table and above bedrock or be
shown to be otherwise capable of handling required design volumes.
E.
The rock in seepage pits shall be covered on the top
and all four sides with a geotextile fabric appropriate for such application.
F.
Seepage pits and trenches shall be kept away from
steep man-made slopes.
G.
In all cases, an overflow system should be provided
to accommodate flows in excess of design criteria. Wherever possible,
a positive drain line should be provided to ensure complete drainage
of a seepage pit within 48 hours after a storm.
H.
Seepage pits or the drains to them must contain a
sediment trap which can be maintained regularly. All downspouts discharging
to seepage beds or trenches should have leaf strainers or grates to
retain debris.
I.
Where seepage pits are designed to contain cisterns
or pipe storage of runoff, access shall be controlled by bar screens
spaced to preclude entry of children and most small animals. All such
facilities shall have one or more securable means of access for cleanout.
J.
All water storage facilities shall be designed to
divert flows in excess of their holding capacity to appropriate areas
of discharge without damage to property.
K.
In addition to seepage beds and trenches, other forms
of stormwater management that result in groundwater recharge are encouraged,
such as the use of lattice blocks for light-duty drive areas or porous
paving, where appropriate. The design for the use of such materials
should be discussed with the Township Engineer.
L.
During site construction, all infiltration practice
components shall be protected from compaction due to heavy equipment
operation or storage of fill or construction material. Infiltration
areas shall also be protected from sedimentation. Areas that are accidentally
compacted or graded shall be remediated to restore soil composition
and porosity. Adequate documentation to this effect shall be submitted
for review by the Municipal Engineer. All areas designated for infiltration
shall not receive runoff until the contributory drainage area has
achieved final stabilization.
M.
Procedures and materials:
(1)
The following procedures and materials shall be required
during the construction of all subsurface facilities:
(a)
Excavation for the infiltration facility shall
be performed with equipment that will not compact the bottom of the
seepage bed/trench or like facility.
(b)
The bottom of the bed and/or trench shall be
scarified prior to the placement of aggregate.
(c)
Only clean aggregate with documented porosity,
free of fines, shall be allowed.
(d)
The tops and sides of all seepage beds, trenches,
or like facilities shall be covered with drainage fabric. Fabric shall
meet the specifications of PennDOT Publication 408, Section 735, Construction
Class 1.
(2)
Perforated distribution pipes connected to centralized
catch basins and/or manholes with the provision for the collection
of debris shall be provided in all facilities unless the Municipal
Engineer agrees that site soils provide superior infiltration (A soils
or highly porous B soils). Where perforated pipes are used to distribute
stormwater to the infiltration practice, stormwater shall be distributed
throughout the entire seepage bed/trench or like facility.
N.
All infiltration practices that serve more than one
lot and are considered a common facility shall have a drainage easement.
The easement shall provide to the Township the right of access.
A.
Open vegetated channels are conveyance systems that
are engineered to also perform as water quality and infiltration practices.
Such systems can be used for the conveyance, retention, infiltration
and filtration of stormwater runoff.
B.
Open vegetated channels primarily serve a water quality
function (WQv), they also have the potential to augment infiltration.
Examples of such systems include, but are not limited to: dry swales,
wet swales, grass channels, and biofilters. Open vegetated channels
are primarily applicable for land uses such as roads, highways, residential
developments (dry swales only) and pervious areas.
C.
Open vegetated channels shall be designed to meet
the following minimum standards:
(1)
The channel shall be designed to safely convey the
ten-year frequency storm event with a freeboard of at least six inches.
Freeboard is the difference between the elevation of the design flow
in the channel and the top elevation of the channel.
(2)
The peak velocity of the runoff from the ten-year
storm shall be nonerosive for the soil and ground cover provided in
the channel.
(3)
The longitudinal slope shall be no greater than 4%.
(4)
Channels shall be trapezoidal in cross section. The
minimum bottom width shall be two feet. The maximum bottom width shall
be eight feet.
(5)
Channels shall be designed with moderate side slopes
of four horizontal to one vertical. Flatter side slopes may be necessary
under certain circumstances.
(6)
The maximum allowable ponding time in the channel
shall be less than 48 hours.
(7)
Channels (for example, dry swales) may require an
underdrain in order to function and dewater.
(8)
Channels shall be designed to temporarily store the
WQv within the system for a maximum period of 48 hours and a minimum
period of one hour.
(9)
Landscape specifications shall address the grass species,
wetland plantings (if applicable), soil amendment and hydric conditions
present along the channel.
(10)
Accumulated sediment within the channel bottom
shall be removed when 25% of the original WQv volume has been exceeded.
(11)
Check dams along the channel length may be warranted.
(12)
The bottom of dry swales shall be situated at
least two feet above the seasonal high water table.
(13)
Additional design information for open vegetated
channels is available in Design of Stormwater Filtering Systems (CWP,
1996).
A.
General responsibilities:
(1)
The owner of stormwater management facilities shall be responsible for the proper operation and maintenance of those facilities during and after construction. An operation and maintenance plan consistent with the requirements of § 73-43C shall be prepared for review and approval by the Municipal Engineer and shall be executed and signed by the Municipal Engineer and applicant.
(2)
The owner of the stormwater management facilities
for a tract shall be responsible for the proper installation and function
of those facilities in accordance with the approved stormwater management
plan. All temporary soil erosion and sedimentation control measures
shall be removed or converted to their permanent configuration in
accordance with an approved erosion control plan. This requirement
in no way precludes the authority of the Chester County Conservation
District to determine when sufficient stabilization has occurred on
a site in order to convert to the permanent stormwater management
facilities. For any project over one acre of disturbance, the applicant
shall be responsible for submitting to the Township as-built plans
of all stormwater facilities included in the approved site plan, and
an explanation of any discrepancies with the approved plans.
[Amended 7-18-2011 by Ord. No. 7-2011]
(3)
Inspection
and BMP operation and maintenance requirements (landowner or owner's
designee).
[Added 12-12-2022 by Ord. No. 3-2022[1]]
(a)
The landowner or the owner's designee shall inspect SWM BMPs,
facilities and/or structures installed under this article according
to the following frequencies, at a minimum, to ensure the BMPs, facilities
and/or structures continue to function as intended:
[1]
Annually for the first five years.
[2]
Once every three years thereafter.
[3]
During or immediately after the cessation of a ten-year or greater
storm, as determined by the Township Engineer. Inspection reports
for inspections during or after the cessation of a ten-year or greater
storm event are only required to be submitted to the Township if requested
by the Township or Township Engineer.
(b)
Inspections should be conducted during or immediately following precipitation
events or in dry weather conditions if the BMP design parameters include
dewatering within a specified period of time. A written inspection
report shall be created to document each inspection. The inspection
report shall contain the date and time of the inspection, the individual(s)
who completed the inspection, the location of the BMP, stormwater
management facility, or structure inspection, observations on performance,
and recommendations for improving performance, if applicable. When
requested by the Township, inspection reports shall be submitted to
the Township within 30 days following completion of the inspection.
[1]
Editor's Note: This ordinance also redesignated former Subsection
A(3) as Subsection A(4).
(4)
Dedication and acceptance of stormwater management
practices.
(a)
As a condition of approval of any subdivision or land development plan, the applicant shall designate an ownership entity for such stormwater management facilities shown on the subdivision or land development plan pursuant to § 73-43B.
(b)
Written offer of such facilities for dedication
to the Township may be made within the time frame required above,
however, the Township is under no obligation to accept dedication.
Should said offer be made to the Township, it shall include a deed
of dedication covering said facilities together with satisfactory
proof establishing an applicant's clear title to said property. Such
documents are to be filed with the Township Manager for review by
the Township Solicitor. Deeds of dedication for stormwater management
facilities may be accepted by resolution of the Township at a regular
meeting thereof.
(c)
The Township may require that stormwater management
facilities remain undedicated, with ownership and maintenance the
responsibility of individual lot owners or a homeowners' association
or similar entity, or an organization capable of carrying out maintenance
responsibilities.
(d)
Regardless of ownership, the applicant shall submit a written offer deeding an access and/or drainage easement to the Township pursuant to § 73-43B. Such easement shall cover the stormwater management facilities, any drainage to and from such facilities at a width as determined in consultation with the Township and the Township Engineer, and shall clearly permit entry for inspection and/or maintenance purposes. When fully executed, be recorded by the landowner at the Chester County Office of the Recorder of Deeds against all parcels affected by the terms of the easement agreement, within 10 days of the Township's approval of the corresponding O&M plan.
[Amended 12-12-2022 by Ord. No. 3-2022]
(e)
Regardless of ownership, the applicant shall
submit to the Township an actual "as-built" plan for the stormwater
management facilities required per the approved stormwater management
plan. The as-built plan shall show all final design specifications
for all permanent stormwater management facilities and shall be prepared
and certified by a licensed professional engineer. The as-built plan
shall be based on an actual field survey performed by a licensed professional
land surveyor. The surveyor shall certify as to the accuracy of the
plan. The as-built plan shall be submitted to the Township for review
and final inspection by the Municipal Engineer. Any performance and/or
financial securities established for the project shall include requirements
for submittal of as-built plans.
B.
Ownership and maintenance. All stormwater management
facilities identified within an approved stormwater management plan
shall be owned and maintained by one, or a combination of, the following
entities:
(1)
Individual on-lot stormwater management facilities:
(a)
Where individual on-lot stormwater management
facilities are proposed, the subdivision and/or land development plan
shall contain a note in a form satisfactory to the Township Solicitor
designating the entity responsible for operation and maintenance of
the on-lot facilities consistent with an approved operation and maintenance
plan and, in the event that the responsible person or entity fails
to do so, granting to the Township the right but not the duty to enter
upon the premises to repair or restore said facilities, to charge
and assess the costs thereof to the owner and to enforce said charges
and assessments by lien upon the property. In addition, the deed for
each lot shall contain a covenant binding on the grantee and all successors
in interest designating the responsibility for operation and maintenance
of the on-lot facilities. The following is an example of such a clause:
|
"UNDER AND SUBJECT, nevertheless, to the following
conditions and restrictions: Prior to the construction of a dwelling
or any other earthmoving activities, Grantee shall construct the permanent
stormwater management facilities as shown on the stormwater management
plan prepared by P.E., dated and last revised and approved by Willistown
Township; thereafter, the Grantee, his heirs, executors, administrators,
successors and assigns ("owner"), at his or their sole cost and expense,
shall operate, maintain and repair said stormwater management facilities
on the lot in accordance with said plan, so that the facilities shall
at all times continue to operate and function in the same manner and
capacity as they were designed. In the event of the failure of the
owner to comply with these conditions and restrictions, Willistown
Township shall have said stormwater management facilities repaired
or restored as required, and the costs thereof shall be assessed to
the owner; said assessment shall be a charge and a continuing lien
upon the property herein. The Township, before it may exercise this
right, shall notify the owner by certified mail of its intention to
take the aforenoted action. The notice shall set forth in what manner
the owner has neglected the operation and maintenance of or repair
to the stormwater management facilities, and if the owner fails to
correct or repair the items listed in the notice from the Township,
then and only then may the Township exercise this right."
|
(b)
In addition to the above, developers of parcels with more than one dwelling unit shall record in the Office of Recorder of Deeds for Chester County a declaration of covenants and restrictions in a form satisfactory to the Township Solicitor describing the responsibility for operation and maintenance of the on-lot facilities, consistent with an approved operation and maintenance plan and incorporating the language set forth in § 73-43B(1)(a) above, as a condition of recording of the final subdivision or land development plan. The terms of this covenant and restriction shall run with the land and be binding upon the initial grantees of each lot within the subdivision, his, her or their heirs, administrators, successors or assigns.
(2)
Homeowners' or condominium association ownership.
Where a homeowners' association is created to own and manage common
facilities, the subdivision and/or land development plan shall contain
a note in a form satisfactory to the Township Solicitor designating
the entity responsible for construction and/or maintenance of the
stormwater management facilities consistent with an approved operation
and maintenance plan and, in the event that the responsible entity
fails to do so, granting to the Township the right but not the duty
to enter upon the premises to repair or restore said facilities, to
charge and assess the costs thereof to each owner of property within
the development and to enforce said charges and assessments by lien
upon each property within the development. In addition, the developer
shall record in the office of the Recorder of Deeds for Chester County
a declaration of covenants in a form satisfactory to the Township
Solicitor setting forth the rights and responsibilities of the homeowners'
association for operation and maintenance of the stormwater management
facilities, as a condition of recording the final subdivision or land
development plan. The terms of this covenant and restriction shall
run with the land and be binding upon the initial grantees of each
lot within the subdivision, his, her or their heirs, administrators,
successors and assigns.
(3)
Municipal ownership. Where the Township has accepted
an offer of dedication of the permanent stormwater management facilities,
the Township shall be responsible for operation and maintenance. Municipal
ownership notwithstanding, the applicant is required to prepare a
stormwater management plan and an operation and maintenance plan,
as defined herein. Upon approval of the stormwater management facilities
by the Township, the applicant shall provide a lump-sum long-term
maintenance payment to the Township, to be reserved and used at all
times by the Township only for costs of operation and maintenance
of the dedicated facilities, as follows:
(a)
Long-term maintenance payment. The long-term
maintenance payment shall be in an amount equal to the present value
of operation and maintenance costs for the facilities for a ten-year
period. The long-term maintenance payment shall be based on a ten-year
cost estimate prepared by the applicant's engineer and reviewed and
approved by the Township Engineer. The amount of the payment shall
include all costs of operation and maintenance, which shall include
but not be limited to typical operation and maintenance costs as well
as costs such as landscaping and planting, tax payments required and
construction of any kind associated with the use, benefit and enjoyment
of the facilities by the owners. In particular, a description of routine
facility operation and day-to-day management requirements and a description
of projected maintenance actions and schedules necessary to ensure
proper operation of stormwater management facilities shall be submitted
for review and approval to the Township Engineer.
(b)
Documentation. The terms of the long-term maintenance
payment shall be documented as part of the stormwater management plan
and the operation and maintenance plan.
C.
Operation and maintenance plan. An operation and maintenance
plan shall be prepared to identify the ownership, operation and maintenance
responsibilities and as-built conditions for all stormwater management
facilities. At a minimum, the operation and maintenance plan shall
include the following:
(1)
Any obligations concerning perpetuation and/or maintenance
of natural drainage or infiltration facilities, and other facilities
identified within the stormwater management plan. Ownership of and
responsibility for operation and maintenance of stormwater management
facilities, including names and contact information, shall be required.
(2)
A description of the permanent stormwater management
practices on the site, explaining how each practice is intended to
function and operate over time. All drainage and access easements
shall be depicted and any site restrictions to be recorded against
the property shall be identified on the plan. All such easements and
restrictions shall be perfected to run with the land and be binding
upon the landowner and any successors in interest.
(3)
A description of the actions, budget and schedule
for operating and maintaining the stormwater management facilities.
This description should be written in a clear manner, consistent with
the knowledge and understanding of the intended user.
(4)
A general description of operation and maintenance
activities and responsibilities for facilities held in common or on-lot,
including but not limited to: lawn care, vegetation maintenance, clean
out of accumulated debris and sediment (including from grates, trash
racks, inlets, etc.), liability insurance, maintenance and repair
of stormwater management facilities, landscaping and planting, payment
of taxes and construction of any kind associated with the use, benefit
and enjoyment of the facilities by the owners. In particular, a description
of routine facility operation and day-to-day management requirements
(as needed) and a description of routine maintenance actions and schedules
necessary to ensure proper operation of stormwater management facilities
shall be submitted.
(5)
Assurances that no action will be taken by any lot
owner to disrupt or in any way impair the effectiveness of any stormwater
management system, setting forth in deed restrictions the ability
of the Township to take corrective measures if it is determined at
any time that stipulated permanent stormwater management facilities
have been eliminated, altered, or improperly maintained, including
the ability of the Township to cause the work to be done and lien
all costs against the property should the required corrective measures
not be taken by the lot owner, following written notification, within
a period of time set by Township Engineer.
(6)
Parties responsible for the long-term operation and
maintenance of stormwater management facilities shall make records
of the installation and of all maintenance and repairs, and shall
retain the records for at least 10 years. These records shall be submitted
to the Township as established by the operation and maintenance plan
or if otherwise required by the Township. In the event of a change,
new information shall be submitted by the BMP or conveyance owner
to the Township within 30 business days of the change.
[Amended 12-12-2022 by Ord. No. 3-2022]
D.
Operations and maintenance agreement.
(1)
The owner of any land upon which permanent stormwater
management facilities and/or BMPs will be placed, constructed or implemented,
as described in an approved stormwater management plan and the operations
and maintenance plan, shall record the following documents in the
Office of the Recorder of Deeds for Chester County, within 15 days
of approval of the operations and maintenance plan by the Township:
(2)
The operation and maintenance agreement shall be substantially
the same as the sample agreement in Appendix C[2] of this chapter.
[2]
Editor's Note: Appendix C is included at the end of this chapter.
(3)
Other items or conditions may be included in the operation
and maintenance agreement where determined necessary to guarantee
the satisfactory operation and maintenance of all permanent stormwater
facilities and BMPs. The agreement shall be subject to the review
and approval of the Township.
A.
Prohibited discharges:
(1)
No person in the Township shall allow, or cause to allow, stormwater discharges into the Township's separate storm sewer system which are not composed entirely of stormwater, except as provided in Subsection B below and discharges allowed under a state or federal permit.
(a)
Contaminated and brownfield sites. Where BMPs may contribute
to the migration of contaminants in groundwater, the water quality
and runoff volume, stream channel protection, and peak rate control
standards shall be met; however, at the Township Engineer's discretion,
the minimum infiltration requirement may be reduced or eliminated
commensurate with the contaminated area, and the required water quality
and runoff control measures may be increased to mitigate the reduced
infiltration requirement for the contaminated area.
[Added 12-16-2013 by Ord. No. 5-2013]
(2)
Discharges that may be allowed based on a finding
by the Township that the discharge(s) do not significantly contribute
to pollution to surface waters of the commonwealth, are:
(a)
Discharges from fire-fighting activities.
(b)
Potable water sources including water line and
fire hydrant flushings, if such discharges do not contain detectable
concentrations of total residual chlorine (TRC);
[Amended 12-12-2022 by Ord. No. 3-2022]
(c)
Noncontaminated irrigation drainage water;
[Amended 12-12-2022 by Ord. No. 3-2022]
(d)
Routine external building washdown (which does
not use detergents or other compounds).
(e)
Noncontaminated HVAC condensation and water
from geothermal systems.
[Amended 12-12-2022 by Ord. No. 3-2022]
(f)
Water from individual residential car washing.
(g)
Spring water from crawl space pumps.
(h)
Uncontaminated water from foundation or from
footing drains.
(i)
Flows from riparian habitats and wetlands.
(j)
Lawn watering.
(k)
Pavement washwaters 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.
(l)
Dechlorinated swimming pool discharges.
(m)
Uncontaminated groundwater.
(n)
Springs.
[Added 12-16-2013 by Ord. No. 5-2013]
(o)
Diverted stream flows.
[Added 12-16-2013 by Ord. No. 5-2013]
(3)
In the event that the Township determines that any of the discharges identified in § 73-44A(2) significantly contribute to pollution of waters of the commonwealth, or is so notified by DEP, the Township will notify the responsible person to cease the discharge.
(4)
Upon notice provided by the Township under § 73-44A(3), the discharger will have a reasonable time, as determined by the Township, to cease the discharge consistent with the degree of pollution caused by the discharge.
(5)
Nothing in this section shall affect a discharger's
responsibilities under state law.
B.
Prohibited connections.
(1)
The following connections are prohibited, except as provided in Subsection A(2) above:
(a)
Any drain or conveyance, whether on the surface
or subsurface, which allows any nonstormwater discharge including
sewage, process wastewater, and wash water to enter the separate storm
sewer system and any connections to the storm drain system from indoor
drains and sinks; and
(b)
Any drain or conveyance connected from a commercial
or industrial land use to the separate storm sewer system which has
not been documented in plans, maps, or equivalent records and approved
by the Township.
C.
Roof drains.
(1)
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 advantageous
to do so.
(2)
Where it can be demonstrated to be more advantageous
to connect directly to streets or storm sewers, connections of roof
drains to streets or roadside ditches may be permitted on a case-by-case
basis as determined by the Township.
(3)
Roof drains shall discharge to infiltration areas
or vegetative BMPs to the maximum extent practicable.
D.
Alteration of BMPs.
(1)
No person shall modify, remove, fill, landscape, or
alter any existing stormwater control or BMP unless it is part of
an approved maintenance program without the prior written approval
of the Township.
(2)
No person shall place any structure, fill, landscaping,
or vegetation into a stormwater control or BMP or within a drainage
easement which would limit or alter the functioning of the stormwater
control or BMP without the prior written approval of the Township.
[Added 7-18-2011 by Ord. No. 7-2011]
A.
Stormwater runoff from hotspots shall be pretreated prior to infiltration
or discharge to surface waters to prevent pollutant runoff. Applicants
shall identify all hotspots on the stormwater plan and include appropriate
BMPs to pretreat runoff to remove pollutants to the maximum extent
practicable and to the satisfaction of the Township engineer. A stormwater
hotspot is a land use or activity that generates higher concentrations
of pollutants than are found in typical stormwater runoff. Examples
of hotspots include:
(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 areas).
(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)
Contaminated sites/brownfields.
(14)
Other land uses and activities as designated by an appropriate
review authority.
B.
The following land uses and activities are not normally considered
hotspots: residential streets and rural highways, residential development,
institutional development, office development, nonindustrial rooftops,
pervious areas except golf courses and nurseries (which may need integrated
pest management (IPM) plans). While streets and highways with average
daily traffic volume (ADT) greater than 30,000 are not considered
stormwater hotspots, it is important to ensure that highway stormwater
management facilities are designed to adequately protect receiving
streams and/or groundwater. The Environmental Protection Agency's
(EPA) NPDES stormwater program requires some industrial sites to prepare
and implement stormwater pollution prevention plans.
A.
Upon presentation of proper credentials, duly authorized
representatives of the Township may enter at reasonable times upon
any property within the Township to inspect the implementation, condition,
or operation and maintenance of the stormwater controls or BMPs in
regard to any aspect governed by this article. Inspections, including
but not limited to a final inspection, of all constructed BMPs, conveyances,
or other stormwater facilities and related improvements may be conducted
to confirm compliance with this article and with the final approved
SWM site plan prior to the issuance of any occupancy permit, use permit,
or other form of final approval of the project by the Township.
[Amended 12-16-2013 by Ord. No. 5-2013]
B.
Stormwater control and BMP owners and operators shall
allow persons working on behalf of the Township ready access to all
parts of the premises for the purposes of determining compliance with
this article.
C.
Persons working on behalf of the Township shall have
the right to temporarily locate on any stormwater control or BMP in
the Township such devices as are necessary to conduct monitoring and/or
sampling of the discharges from such stormwater control or BMP.
D.
Unreasonable delays exceeding 24 hours in allowing
the Township access to a stormwater control or BMP is a violation
of this article.
[Amended 12-12-2022 by Ord. No. 3-2022]
E.
The following as it pertains to any easements, covenants and deed
restrictions established for each applicable BMP or conveyance:
[Added 12-12-2022 by Ord.
No. 3-2022]
(1)
Boundaries delineated with bearings and distances shown that encompass
the BMP or conveyance and that includes a ten-foot perimeter area
surrounding these features and sufficient vehicular ingress to and
egress from a public right-of-way and roadway;
(2)
Labels specifying the type and purpose of the easement, covenant,
or deed restriction and who it benefits; and
(3)
Labels with reference to any corresponding easement agreement, covenant,
deed restriction or other document to be recorded.
