Bethany Culvert Emergency Storm Damage Project

Bethany Culvert Emergency Storm Damage Project

Bethany Culvert failed during the January 2023 storms that were declared a disaster (DR-4683-CA) across Santa Cruz County by California Governor Gavin Newsom. Located on West Cliff Drive between Woodrow Avenue and 1004 West Cliff Drive (see Figure 1), the culvert and viaduct structure consist of a concrete arch culvert in the channel of Bethany Creek that discharges into Monterey Bay. Around the culvert, there is fill to allow the roadway to span the creek and perpendicular to the culvert, there are headwalls to retain the fill. On the west side of the culvert, there is a sea cave concealed by rip rap that extends under the roadway an unknown distance. Due to intense rainfall coupled with large wave swells, drains separated from the culvert and the coastal headwall began to rotate out. The visible portions of the culvert and headwalls are severely deteriorated and in very poor condition. The deterioration is due to age, poor-quality concrete, exposure to seawater, and lack of adequate reinforcing. Some portions of the structure appear to be mechanically detached from the substructure due to significant cracks. Due to the poor-quality concrete and observations of concrete deterioration, it was determined that most of the 100-year-old culvert structure has reached the end of its life span and is not reparable. To reconstruct Bethany Culvert, the proposed project involves removing the damaged structure and replacing it with a new culvert and headwalls on the coastal and inland sides of the culvert overpass, grading and repaving the roadway, and restoring sidewalks and storm drain infrastructure. The style of the replacement structure will match the architecture/appearance of the existing structure. A new concrete cast-in-place culvert and headwalls will provide the opportunity to improve the creek drainage and roadway configuration. The new headwalls can be placed in the same location or pulled slightly inland from the original and not encroach on the coast. The new headwalls will be supported by spread footings, eliminating the need for drilled piers, and new code compliant barrier rails will be constructed. The road surface will be flattened out, raising the lowest elevations approximately one foot to reduce flooding and maintain road drainage to the new drain inlets. The underlying sea cave will be sealed and filled to eliminate the risk of further erosion and sink holes. Except in front of the sea cave, existing rock armoring will be removed where feasible. Some rock armoring is anticipated on the eastern wall closure to transition from the new wall to natural terrace deposit. All of the existing backfill and utilities will be replaced with new materials. The project includes best management practices (BMPs) to prevent erosion, sedimentation, and the discharge of pollutants during construction, protecting marine resources. For example, silt fences and catch basin protections will be used for the duration of construction, and straw bales, pumps, and other containment/soaking devices will be used in case of spillage. Additionally, construction will take weather into account by scheduling excavation and concrete pours outside of forecasted rain events, high surf, high tide, and storms, and covering soil stockpiles and positioning equipment and materials at the end of each shift. The suite of BMPs will ensure that no debris, soil, silts, sand, rubbish, cement or concrete or washing thereof, oil or petroleum products or other earthen material from any construction or associated activity will be allowed onto the beach below or adjacent marine environment.

Santa Cruz

Santa Cruz

San Francisco Bay Area

Santa Cruz