On January 4, 2023 Governor Newsom proclaimed a state of emergency throughout California to support the ongoing response to recent winter storms. Due to the recent rains, there were three culvert locations along Higgins Canyon Road that required emergency replacement or repair. The culvert at Higgins Canyon Road Mile 1.8 had water undercutting the culvert inlet, allowing water flow beneath the culvert which had destabilized the road bank and washed out road bank soils. Repairs included a headwall floor to direct water into the culvert inlet, addition of a soil cap at the road shoulder, and addition of rock energy dissipation at the culvert outlet. The 18" CMP culvert at Higgins Canyon Road Mile 2.9 had detached and water was flowing beneath the road, outside of the culvert, which was undercutting and destabilizing the road. The culvert was replaced with an 18" HDPE culvert. The 15" CMP culvert at Higgins Canyon Road Mile 3.5 had detached and water was flowing beneath the road, outside of the culvert, which was undercutting and destabilizing the road. The culvert was replaced with a 15" HDPE culvert.
At 143 Chesham, the road shoulder has been destabilized by surface flow run-off. The road shoulder will be repaired with a rock and soil repair. Heavy equipment would be operated from the roadway. Post-construction erosion control BMPs would be installed to conserve soil resources and protect water quality. Work will be conducted using best management practices detailed in the County of San Mateo Routine Maintenance Program Manual.