Background
A river followed a natural path that passed through a golf course. In 2011, flooding from a hurricane caused significant erosion and damage that rerouted the channel and caused movement of a 115-foot-long golf cart bridge. As part of the golf course’s recovery from the storm, the channel was recreated. A new bridge was constructed in 2013 with abutments on both sides of the channel and a central pier with a spread footing. To prevent further damage to the bridge and channel, the banks of the river were armored with rocks, and the central pier and abutments were protected with heavy stone to mitigate erosion and undermining of the foundations. High flows in December of 2020 and October of 2021 caused the channel to shift, as well as undermining of the central pier.
Services Provided
After the 2021 event, the pier had moved significantly, and the heavy fill around the footing was no longer visible. Rimkus was retained to investigate the movement of the bridge and pier. We performed a forensic assessment of the structural damage, including a review of weather and river flow data, review of design documents for the bridge, and a physical site inspection. During the site inspection, we observed that material was scoured from around and below the structure, allowing the pier to move down. The bridge was heavy and rigid enough not to wash it away but had settled without the supporting soil below the central pier.
The bridge was determined to be inadequately designed against natural and expected shifting of the river. For longevity, the bridge needed more support in the form of a deeper foundation below the central pier.