A. Any stormwater facility located on state highway rights-of-way shall be subject to approval by the Pennsylvania Department of Transportation (PennDOT).
B. Pretreatment shall be provided prior to infiltration.
C. All wet basin designs shall incorporate biologic controls consistent with the West Nile Guidance found in Appendix F.
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D. Any stormwater management facility (i.e., detention basin) designed to store runoff and requiring a berm or earthen embankment required or regulated by this Part shall be designed to provide an emergency spillway to handle flow up to and including the one-hundred-year proposed conditions. The height of embankment must provide a minimum 1.0 foot of freeboard above the maximum pool elevation computed when the facility functions for the one-hundred-year proposed conditions inflow. Should any stormwater management facility require a dam safety permit under PaDEP Chapter 105, the facility shall be designed in accordance with Chapter 105 and meet the regulations of Chapter 105 concerning dam safety which may be required to pass storms larger than the one-hundred- year event.
E. Any facilities that constitute water obstructions (e.g., culverts, bridges, outfalls, or stream enclosures), and any work involving wetlands governed by PaDEP Chapter 105 regulations (as amended or replaced from time to time by PaDEP), shall be designed in accordance with Chapter 105 and will require a permit from PaDEP.
F. Any other drainage conveyance facility that does not fall under Chapter 105 regulations must be able to convey, without damage to the drainage structure or roadway, runoff from the twenty-five-year design storm with a minimum 1.0 foot of freeboard measured below the lowest point along the top of the roadway. Any facility that constitutes a dam as defined in PaDEP Chapter 105 regulations may require a permit under dam safety regulations. Any facility located within a PennDOT right-of-way must meet PennDOT minimum design standards and permit submission requirements.
G. Any drainage conveyance facility and/or channel not governed by Chapter 105 regulations, must be able to convey, without damage to the drainage structure or roadway, runoff from the twenty-five-year design storm. Conveyance facilities to or exiting from stormwater management facilities (i.e., detention basins) shall be designed to convey the design flow to or from that structure. Roadway crossings located within designated floodplain areas must be able to convey runoff from a one-hundred-year design storm. Any facility located within a PennDOT right-of-way must meet PennDOT minimum design standards and permit submission requirements.
H. Storm sewers must be able to convey proposed conditions runoff from a twenty-five-year design storm without surcharging inlets, where appropriate.
I. Adequate erosion protection shall be provided along all open channels, and at all points of discharge.
J. The design of all stormwater management facilities shall incorporate sound engineering principles and practices. The municipality reserves the right to disapprove any design that would result in the construction in or continuation of a stormwater problem area.
K. No stormwater detention facility shall be placed within 50 feet of a special geologic feature. No stormwater conveyance facility shall be constructed within 50 feet of a special geologic feature, unless it is constructed of concrete pipe utilizing watertight joints, or an approved equal.
15. Editor's Note: Appendix F is included at the end of this chapter.