High Street Dam removal and Bridge replacement

Challenge

Over the life of the Town River in Bridgewater, MA there have been many significant changes to adapt to the needs of the people. In 1850 a bridge was built across the river to connect peoples living on both sides of the river. In 1919, a dam was constructed (known as the High Street Dam) to supply hydro-energy to a local mill. Both of these projects, which were useful at their time of construction, in 2018 were seen as hazards to the wildlife and community.

SLR was initially commissioned by The Nature Conservancy (TNC) to conduct a feasibility analysis for the removal of High Street Dam and the restoration of the 2.5-mile impounded portion of the Town River.

SLR concluded that the removal of the dam and restoring the riverbed would provide significant benefit to the community (improving flood resiliency) and improve herring and other fish’s ability to access the Atlantic Ocean to spawn. However, with the removal of the dam, SLR identified that structural integrity of High Street Bridge (located 150 feet upriver of the dam) would be significantly impacted.

SLR began work on developing a feasibility plan that would address both the High Street Dam and High Street Bridge, knowing that addressing one without addressing the other would leave the community vulnerable to potentially sudden and catastrophic failure.

Solution

Knowing that the dam was slated to be removed, SLR worked with the Town of Bridgewater to address and design a modern replacement for the High Street Bridge.

The replacement structure was designed to be a 55-foot span steel girder bridge with reinforced concrete deck. The bridge would be founded on cast-in-place abutments supported by drilled shafts socketed into the bedrock. The modern bridge was designed with climate resilience in mind, able to withstand 500-year-floods.

When the design for the new bridge was approved, SLR continued to support the project by helping the town apply for federal funding for the project and oversaw construction of the bridge.

Impact

The project was completed with both the dam removed and the new bridge completed in November 2023.

The Town River, no longer impeded by the old bridge and dam, is modernized to meet the needs of the community. Fish and canoers are now able to travel through the area without issue, the properties around Town River are at significantly less risk of flooding, and the area is now prepared for another 150 years of use.