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Consultants recommend $1.7 million bridge replacement to reduce Stone Edge Road flooding
Summary
Consultants told the East Rockhill supervisors that replacing the Stone Edge Road culvert with a 50-foot span beam bridge (Alternative B) would largely eliminate closures for regular storms but would cost an estimated $1.7 million and require FEMA map revisions and potential easements.
Engineers presenting to the East Rockhill Township Board of Supervisors on June 24 recommended replacing the existing Stone Edge Road box culvert with a 50-foot span beam bridge to reduce frequent roadway flooding.
Consultant John Liberatore, P.E., PMP, CBSI, and Mr. Greg Richardson, P.E., said the current 14-foot-long by 3-foot-high box culvert was designed to flood for a 1-year storm event and currently passes about 236 cubic feet per second, roughly 87% of a 1-year storm. They evaluated three alternatives under PennDOT criteria for a 10-year storm and recommended Alternative B: a 50-foot span bridge on a roadway profile raised 2.75 feet, estimated to pass about 1,150 cubic feet per second of the 1,160 cfs 10-year design target. The consultants estimated construction-only costs at approximately $1,700,000.
"There is nothing feasible that can be done for the culvert to never flood, that would require an 800 feet long bridge," Liberatore said, emphasizing trade-offs between roadway elevation and upstream impacts. He added that Alternative B would allow the roadway to remain open during regular storms but not eliminate flooding during extreme events.
The presentation flagged two practical constraints: a required FEMA flood map revision and the possible need to acquire easements if hydraulic changes affect upstream or downstream properties. Liberatore and Richardson warned that raising the road or widening the channel could shift flood impacts onto neighboring properties, so owner input and easement negotiations would likely be required.
Several residents described localized flooding upstream. Robert Smith said his basement floods and urged the board to examine the SEPTA-owned railroad bridge nearby; consultants noted SEPTA ownership limits Township authority over that structure. Residents also asked about alternative bridge designs and whether new stormwater basins tied to recent development would help; the engineer said basins could provide only marginal improvement because they delay flow but do not change peak discharge for larger storms.
Township staff said they will ask consultants to prepare a follow-up proposal to study structural alternatives to Alternative B that aim to reduce roadway flooding while minimizing upstream and downstream impacts, and to identify potential grant funding sources.
Next steps: the board received the preliminary findings and directed staff to return with a proposal for further study, including structural options and funding strategies.
