[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 the following:
[Amended 12-12-2022 by Ord. No. 3-2022; 7-15-2024 by Ord. No. 4-2024]
[1] 
Any net increase of regulated impervious surface up to 800 square feet, calculated cumulatively from December 16, 2013. Improvements to a lot, including incremental or phased projects, that result in a cumulative regulated impervious surface coverage to be greater than the 800-square-foot exemption shall require stormwater management planning for the total amount of regulated impervious surfaces, unless otherwise provided herein.
[2] 
The square footage of surface water area for a freeboard swimming pool.
[3] 
Concrete pads, stone beds, or other similar impervious material of 15 square feet or less supporting generators, air-conditioning units, oil or gas tanks, or other similar structures, up to a total of 75 square feet.
(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:
(a) 
Erosion and sediment control during earth disturbance activities (e.g., during construction); and
(b) 
Water quality protection measures after completion of earth disturbance activities (i.e., after construction), including operations and maintenance.
(11) 
No regulated earth disturbance activities within the Township shall commence until the requirements of this article are met.
(12) 
Postconstruction water quality protection shall be addressed as required by § 73-37E.
(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.
(5) 
Culverts, bridges, storm sewers, or any other facilities which must pass or convey flows from the tributary area and any facility which may constitute a dam subject to permit by DEP under 25 Pennsylvania Code Chapter 105.
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.
(b) 
Establish a riparian buffer area according to Article III and Article XII, § 73-61.
(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.
(g) 
Provide for water quality protection in accordance with § 73-37E, water quality requirements.
(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.
(l) 
Provide stream bank erosion protection in accordance with any discharges anticipated and the release rates designated in the stormwater management districts described in § 73-37F.
(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.
(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.
(1) 
Recognizing that the Township contains three distinct watersheds, the following stormwater management districts are established:
(a) 
Crum Creek Stormwater District.
(b) 
Ridley Creek Stormwater District.
(c) 
Valley Creek Stormwater District.
(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]
(5) 
All areas of the Township that do not have specific release rates as specified in § 73-37F(2), (3) or (4) above shall be required to conform with § 73-37G when developing controls.
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.
[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]).
(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.
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).
[Amended 7-18-2011 by Ord. No. 7-2011; 12-12-2022 by Ord. No. 3-2022; 4-13-2026 by Ord. No. 3-2026]
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. 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.
(3) 
Inspection and BMP operation and maintenance requirements (landowner or owner's designee).
(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.
(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.
(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.
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:
(a) 
The operations and maintenance plan, or a summary thereof;
(b) 
Operations and maintenance agreement; and
(c) 
Access and/or drainage easements.
(2) 
The operation and maintenance agreement shall be substantially the same as the sample agreement in Appendix C[1] of this chapter.
[1]
Editor's Note: Appendix C is included as an attachment to 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.
(4) 
The Township may suspend or revoke any approvals granted for the project site upon discovery of the failure of the owner to comply with § 73-43.
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.
(3) 
No person shall allow the BMP or conveyance to exist in a condition which does not conform to the approved plan or this agreement.
[Added 9-9-2024 by Ord. No. 6-2024]
(4) 
No person shall dispose of, discharge, place or otherwise allow pollutants, including, but not limited to, deicers, pool additives, household chemicals, and automotive fluids, to directly or indirectly enter any BMP or conveyance.
[Added 9-9-2024 by Ord. No. 6-2024]
[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.