Boulder Creek Bridge Scour Repair Project

ongoing

The project is in Santa Cruz County on State Route 236 at Boulder Creek Bridge (post mile 4.27) in the census-designated town of Boulder Creek. In this location, State Route 236 is a conventional two-lane, undivided highway. Boulder Creek Bridge was constructed in 1926 as a small, single-span reinforced concrete girder bridge on top of reinforced concrete abutments and wing walls with concrete bridge railing. Boulder Creek Bridge is a single-span bridge with no piers located in the creek. The existing bridge is about 22 feet long and 24 feet wide. Each travel lane is 11 feet wide with 1-foot shoulders. Bridge scour is the erosion of sediment from around bridge abutments or piers. Scour, caused by swift-moving water, can scoop out scour holes, compromising the integrity of a structure. Water flowing in Boulder Creek has contributed to scour along Abutment 1, specifically on the northern end of the abutment upstream of Boulder Creek. The proposed work would include the placement of a 1.5-foot-thick and 6-foot-high reinforced concrete curtain wall along the full length of the existing Abutment 1 spread footing, which is about 27 feet long. The top of the proposed curtain wall would match the current elevation of the existing top of the Abutment 1 footing. The curtain wall will wrap around the upstream (northern) side of the abutment to protect the concrete from erosion. Additionally, cracks and defects in the existing concrete on the underside of the bridge at Abutment 1 would be patched.