A.
Where applicable, stormwater management facilities or programs shall comply with the requirements of Chapter 102, Erosion Control, Chapter 105, Dam Safety and Waterway Management, and Chapter 106, Flood Plain Management, of Title 25, Rules and Regulations, of the PADER.
B.
Stormwater management facilities which involve a state highway shall be subject to the approval of PADOT.
C.
Stormwater management facilities located within or affecting the floodplain of any watercourse shall also be subject to the requirements of any municipal or county ordinance which regulates construction and development within areas which are subject to flooding.
D.
Stormwater management facilities must be designed so that the postdevelopment runoff rates equal the predevelopment runoff rates. Exceptions to this are the critical areas defined in § 91-8. The predevelopment and postdevelopment runoff rates and volumes shall be calculated for the appropriate design storm events presented in § 91-9C.
E.
Additional studies and a higher level of control other than management practices and/or larger storm event designs than the minimum required by this chapter may be required by the township to assure adequate drainage to protect life and property and otherwise meet the intent of this chapter.
F.
In cases where the nature of any regulated activity involves the use of fertilizer or involves other practices which inherently involve the use or production of larger levels of nutrients, such as but not limited to golf courses, commercial nurseries or greenhouses, or if the regulated activity by virtue of its location adjacent to a stream or other water body on steep slopes or other conditions would result in a threat of larger levels of nutrients, the Board of Supervisors may require that stormwater management be required in accord with this subsection. Stormwater management facilities must be designed so that the postdevelopment runoff pollutant loads for total phosphorous and sediment equal the water quality criteria of the receiving waters as established by the LWWMD, which are five-tenths (0.5) milligrams per liter for phosphorus (as total soluble phosphorus) and 110 milligrams per liter for sediment (as total suspended solids). Exceptions to this are the critical areas defined in § 91-8. The predevelopment and postdevelopment runoff pollutant loads for total phosphorus and sediment shall be calculated for the appropriate land use types.
G.
Adequate drainage.
(1)
It is the responsibility of the developer to provide adequate drainage. Adequate drainage must have the hydraulic characteristics to accommodate the maximum expected flow of stormwaters for the watershed or portion thereof, for the required design year storm. Adequate drainage is to be designated to:
(a)
Account for on-site stormwaters at ultimate development with proposed controls and any runoff entering the site from adjacent property based on the current Comprehensive Development Plan prepared by the Wayne County Planning Department.
(b)
Honor natural drainage divides.
(c)
Convey stormwater to a natural outfall.
(d)
Not adversely affect the adjacent or neighboring properties, including the concentration of runoff at property boundaries.
(e)
Not adversely affect the water quality of receiving waters.
(2)
It is the responsibility of the developer to provide adequate drainage for the proposed development and upstream watershed along or through his or her property to a natural outfall. Staged construction will be considered for perimeter and off-site improvements where the developer's engineer can show that it is feasible. Off-site drainage improvements will be required to prevent the proposed development from having any significant detrimental effect on the downstream facilities to the point of a natural outfall.
(3)
If a developer concentrates dispersed (sheet) flow or redirects flow to exit at another location on the property, the developer is responsible for constructing an adequate channel on the adjacent property and on all downstream properties until a natural outfall is reached. The developer shall also be responsible for obtaining and/or purchasing any easement or right of entry from any affected downstream property owners, if such easement can be obtained from a willing seller.
H.
A natural outfall shall have sufficient capacity to receive the design storm peak runoff from the watershed without deterioration of the facility and without adversely affecting property in the watershed. This natural outfall may be a river, creek or other drainage facility so designated by the Wayne County Planning Department for the proposed system.
I.
Detention is the provision of an acceptable storage area for stormwater with the use of a control structure providing a significant reduction in the peak discharge of stormwater. Detention of stormwater is desirable in many cases to alleviate existing downstream drainage problems and to preclude the development of new ones. Detention or retention is mandatory where the existing downstream drainage system is clearly inadequate and its expansion or improvement is either financially prohibitive or aesthetically unacceptable. The township reserves the right to waive the requirement for detention of stormwater where the township determines that its use is not in the public interest and where alternatives may apply.
J.
Innovative stormwater management systems.
(1)
Innovative stormwater management systems may be used when approved by the Township. Various combinations of stormwater management systems should be developed to suit the particular, unique requirements of the development and topographic features of the development size. Approval of a proposed stormwater management control facility using these innovative methods shall depend on the effectiveness of the facility in controlling the impacts of postdevelopment runoff rates and volumes and in mitigating the nonpoint source pollutant loadings along with the facility's ability to meet the design criteria of § 91-10 and the design and construction specifications of Appendix D of this chapter.[1] The following is a partial listing of control methods which can be used in stormwater management facilities where appropriate:
(a)
Agricultural waste storage structure.
(b)
Bank stabilization.
(c)
Channel modification.
(d)
Cistern storage.
(e)
Conservation tillage.
(f)
Contour farming.
(g)
Cover cropping.
(h)
Critical area planting.
(i)
Diversion.
(j)
Farmland management.
(k)
Fencing.
(l)
Filter strips.
(m)
Floodplain management.
(n)
Impoundments.
(o)
Infiltration, pits and trenches.
(p)
Land surface controls and zoning.
(q)
Parking lot storage.
(r)
Porous and grid-modular pavement.
(s)
Road paving.
(t)
Rooftop detention.
(u)
Sediment basin.
(v)
Seepage areas.
(w)
Storm sewers.
(x)
Street cleaning.
(y)
Strip-cropping.
(z)
Terracing.
(aa)
Wetland preservation.
[1]
Editor's Note: Said appendix is included at the end of this chapter.
(2)
General descriptions, including the operation and maintenance of these stormwater management facilities, are provided in Appendix D of this chapter.[2]
[2]
Editor's Note: Said appendix is included at the end of this chapter.
K.
Access to facilities shall be provided for maintenance and operation. This access shall be a cleared access that is, when possible, approximately 20 feet wide. Proximity of facilities to public rights-of-way shall be encouraged in order to minimize the length of accessways. Multiple accesses shall be encouraged for major facilities.
L.
All control facility designs shall conform to the applicable standards and specifications of the following governmental and institutional agencies:
(1)
American Society of Testing and Materials (ASTM).
(2)
Asphalt Institute (AI).
(3)
Conservation District.
(4)
Federal Highway Administration (FHWA).
(5)
National Crushed Stone Association (NCSA).
(6)
National Sand and Gravel Association (NSGA).
(7)
Pennsylvania Department of Environmental Resources (PADER).
(8)
Pennsylvania Department of Transportation (PADOT).
(9)
United States Department of Agriculture, Soil Conservation Service, Pennsylvania (USDA, SCS, PA).
M.
Control facilities which receive stormwater from areas, as determined by the Board of Supervisors, which are a potential source of oil and grease contamination shall include a baffle, skimmer, grease trap or other mechanism suitable for preventing oil and grease from leaving the facility in concentrations that would cause or contribute to violations of applicable water quality standards in the receiving waters.
N.
No harm option.
(1)
The developer has the option of using a less restrictive runoff control (including no detention) if the developer can prove that no harm would be caused by discharging at a higher runoff rate than that specified by the criteria of this chapter. Proof of no harm would have to be shown from the development site through the remainder of the downstream drainage network to the headwaters of Lake Wallenpaupack. Proof of no harm must be shown using the capacity criteria specified by references of Subsection L above and Appendix D[3] if downstream capacity analysis is a part of the no harm justification.
[3]
Editor's Note: Said appendix is included at the end of this chapter.
(2)
Attempts to prove no harm based upon downstream peak flow, versus capacity analysis, shall be governed by the following provisions:
(a)
The peak flow values to be used for downstream areas for various return-period storms shall be the values from the TR-20 Runoff Model for the Lake Wallenpaupack Watershed. These flow values would be supplied to the developer by the Township Engineer upon request.
(b)
Any available capacity in the downstream conveyance system, as documented by a developer, may be used by the developer only in proportion to his or her development site acreage relative to the total upstream undeveloped acreage from the identified capacity (i.e., if his or her site is 10% of the upstream undeveloped acreage, he or she may use up to 10% of the documented downstream available capacity).
(c)
Developer-proposed runoff controls which would generate increased peak flow rates at documented storm drainage problem areas would, by definition, be precluded from successful attempts to prove no harm, except in conjunction with proposed capacity improvements for the problem areas.