Salt Creek Canyon

The California Department of Transportation (Caltrans) District 3 is conducting the Salt Creek Canyon Project on State Route 20 in Colusa County, extending from the Colusa/Lake County line to the Interstate 5 intersection. This comprehensive safety improvement initiative includes widening nonstandard shoulders, pavement and drainage rehabilitation, the installation of rumble strips, and upgrading guardrails and end treatments to Manual of Assessing Safety Hardware (MASH) standards. The project also incorporates stormwater treatment via bioswales and bio strips, along with vegetation management and the installation of rock slope protection. A critical component of the project is a geotechnical investigation to evaluate subsurface conditions for the design and construction of earth retaining systems, specifically soldier pile walls with ground anchors or soil nail walls and associated embankments. This scope of work involves drilling, visual logging, in-situ testing, and the sampling of soil and rock, as well as the execution of Seismic Refraction Tomography and Electrical Resistivity Tomography. The geotechnical portion of the project is categorized as exempt under CEQA Section 15306 for information collection and is categorically excluded under NEPA. Coordination with the Native American Heritage Commission is ongoing to ensure the protection of tribal cultural resources.