Salson Trail and Culvert Project

Salson Trail and Culvert Project

Salson Trail is an unpaved fire road that provides important emergency firefighting access to the San Juan Canyon and Sugarloaf open spaces, which abut residential neighborhoods on all sides (Figure 1, Figure 2; attached). It also supports recreational use by hikers and bicyclists and provides maintenance access to a 10-inch-diameter vitrified clay pipe (VCP) City of Belmont sewer main serving approximately 400 houses in the adjacent residential area to the south. The proposed project addresses damage to the Salson Trail roadway and an existing 48-inch-diameter corrugated metal pipe (CMP) culvert that conveys East Laurel Creek flows beneath the Trail. During the large storm events of December 2022 – January 2023, the Creek overtopped the Trail, eroding out a portion of the road and severely damaging the culvert. The north end of Salson Trail has been closed since that time to reduce risks to public safety, and firefighting access is compromised as a result. A segment of existing sewer main that crosses the culvert in the subsurface (about 50 linear feet in total) is also damaged and requires replacement. The Salson Trail and Culvert Project is proposed to restore culvert function, prevent sanitary sewer leaks and spills, and restore firefighting access at the urban/wildland interface. Specific project objectives include • replacing and upsizing the failing culvert to reduce the potential for similar damage in the future • replacing the damaged and at-risk segment of sewer main • repairing Salson Trail so it can be reopened for firefighting access and recreational use The Project would include the following elements (Figure 3, attached). • A new 60-inch-diameter RCP culvert • Headwall, wingwalls, and “debris catcher” poles at the upstream end of the culvert • Headwall and riprap apron at the downstream end of the culvert • Replacement of the damaged section of 10-inch-diameter sewer line with high-density polyethylene (HDPE) pipe at the same diameter • Restoration of the Salson Trail where it was damaged by floodflows Extensive Avoidance and Minimization Measures (AMMs) have been incorporated into the Project to avoid adverse impacts on water quality, special-status species, and habitat associated with East Laurel Creek. Following construction, riparian habitat disturbed for construction access will be restored per a Habitat Mitigation and Monitoring Plan (Redtail Consulting 2024) subject to review by the California Department of Fish and Wildlife and San Francisco Bay Regional Water Quality Control Board.

Belmont

San Mateo

Northern California, San Francisco Bay Area

San Mateo