(a) All wet basin designs shall incorporate biologic controls consistent with the West Nile Guidance found in Appendix E, PennDEP document 363-0300-001 “Design Criteria - Wetlands Replacement/Monitoring”, or contact the Pennsylvania State Cooperative Wetland Center (www.wetlands.psu.edu/
) or the Penn State Cooperative Extension Office (www.extension.psu.edu/extmap.html
).
(b) Any stormwater basin required or regulated by this chapter designed to store runoff and requiring a berm or earthen embankment shall be designed to provide an emergency spillway to handle flow up to and including the 100-year proposed conditions. The height of embankment must provide a minimum recommended one foot of freeboard above the maximum pool elevation computed when the facility functions for the 100-year proposed conditions inflow. Should any stormwater management facility require a dam safety permit under 25 Pa. Code Ch. 105, the facility shall be designed in accordance with 25 Pa. Code Ch. 105 and meet the regulations of 25 Pa. Code Ch. 105 concerning dam safety. 25 Pa. Code Ch. 105 may require the passing of storms larger than 100-year event.
(c) 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 25-year storm event. The larger the events (50-year and 100-year) must also be safely conveyed in the direction of natural flow without creating additional damage to any drainage structures, nearby structures or roadways.
(d) Conveyance facilities to or exiting from stormwater management facilities (i.e., detention basins) shall be designed to convey the design flow to or from the facility.
(e) Roadway crossings or structures located within designated floodplain areas must be able to convey runoff from a 100-year design storm consistent with Federal Emergency Management Agency National Flood Insurance Program - Floodplain Management Requirements.
(f) Any facility located within a PennDOT right-of-way must meet PennDOT minimum design standards and permit submission requirements.
(g) 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-89-0I6) and the PennDEP Erosion and Sediment Pollution Control Program Manual (Publication No. 363-2134-008).
(Ord. 928, passed 6-18-2014)