Minimum roadway crossing requirements. Roadway crossing, including pipes, bridges, storm sewers or any other drainage conveyance facility must be able to convey, without damage to the drainage structure or roadway, runoff from the twenty-five-year design storm with a minimum of 1.0 foot of freeboard measured below the lowest point along the roadway. Roadway crossings located within designated floodplain areas must be able to convey runoff from a one-hundred-year design storm with a minimum of 1.0 foot of freeboard measured below the lowest point along the top of the roadway. Any facilities that constitute stream enclosures, as described in 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. Other requirements can be added, such as methods of detention or control, which may be utilized in stormwater management systems. These would include detention basins, rooftop storage, parking lot and street ponding, seepage pits and cisterns, porous pavement, grassed channels, swales, vegetative strips and decrease of impervious coverage.