Two Butler bridges over Sullivan Run will be replaced and widened in efforts to lessen the likelihood of flooding along the waterway.
John Evans, the zoning officer for the city, said he expects work on the West New Castle Street and West Cunningham Street bridges to begin next spring.
The city will be partnering with the state Department of Transportation to replace the New Castle Street bridge, while PennDOT also is planning to replace the Cunningham Street bridge.
The city will pay 20 percent of the estimated $1.5 million New Castle Street project.
The state is responsible for the Cunningham Street Bridge, which is Route 68.
Evans said the two bridges are not expected to be replaced at the same time to allow for efficient detours and traffic patterns in the city. Both bridges will be closed during the replacement projects.
Evans said the New Castle Street bridge project is expected to take about 4 months to complete.