Borough of Downingtown
AEG was responsible for assisting the Borough of Downingtown with determining the regulatory and hydraulic impacts and hydraulic design of a proposed pedestrian bridge over the East Branch of the Brandywine Creek to be located just downstream of the Business Route 30 (East Lancaster Avenue) Bridge. Included with the project/analysis is a proposed trailhead parking area located on the west side of the creek and a trail to be located along the east bank of the creek and under the east span of the East Lancaster Avenue Bridge (Business Route 30). The existing trail directed pedestrians to an at-grade crossing at Business Route 30. The project, in part, is to establish a trailhead and extend and connect it to the existing regional Brandywine Trail and to provide improved pedestrian safety. The project area is located within an urban area and within a FEMA-designated floodplain and regulatory floodway. Therefore, by regulation, the hydraulic design of the proposed pedestrian bridge must have no adverse impact (zero rise) on the 100-year floodplain or regulatory floodway. Consequently, obtaining the PADEP Chapter 105/ACOE Section 404 Joint Permit Application was key to the success of this project. The project goals for the bridge were complicated because the bridge needed to be ADA accessible, requiring ramps and additional components to accommodate ADA requirements which added to the proposed footprint of the bridge. AEG was able to develop project and bridge hydraulic design concepts that reached the project goals and fell within this severely restrictive regulation. Upon reviewing the results of our investigations, the Borough decided to proceed with this project. These presented concepts included: locating the bridge at the optimum location downstream of the Lancaster Avenue Bridge and away from buildings and other hydraulic restrictive areas; having the bridge deck above the 100-year floodplain; promoting an “open” bridge design for the ramp, deck and substructure components that minimized hydraulic impacts; setback of the abutments to the greatest extent possible as to not restrict flow; and location analysis of the proposed trail and trailhead parking and recommendations of grading within the floodplain and under Lancaster Avenue Bridge to mitigate impacts. AEG was involved with planned hydraulics and hydrology studies and report preparation; environmental assessments and impacts; wetland investigations; NEPA documentation; and PADEP Chapter 105/ACOE Section 404 Joint Permit Application, regulatory coordination with the Borough, Chester County, and the Pennsylvania Department of Environmental Protection (PA DEP).