The California Department of Transportation (Caltrans), using state funds only, proposes to protect the roadway of State Route 96 in Siskiyou County at post mile 33.2 from rockfall. The purpose of the project is to reduce the risk of rocks falling onto the highway, minimize maintenance efforts, and reduce worker exposure. The project is needed because the project area has a history of frequent rockfall that poses risks to travelers and maintenance crews. During inclement weather, this area is prone to rockfall and having large amounts of mud move down the adjacent hillside. Large storm events typically overwhelm the existing damaged culvert and roadside ditch and the overflow pushes mud, rock, and other debris across the highway and into the Klamath River. These debris flows have been up to 18 inches deep, requiring maintenance crews to perform emergency lane closures and work under the slide area during storms. The proposed project is adjacent to the Automatic Slide Project, which installed rockfall drapery on the hillside in 2014.
The proposed work includes excavating a catchment basin at the toe of the slope and lining it with concrete, tapering back the hillside, converting the existing culvert to function as an emergency overflow culvert, and adding a new culvert that is 88 feet long and 24 inches in diameter that will separate debris and water. The catchment basin would be approximately 50 feet long, 40 feet wide, up to 3 feet deep, and would collect rocks and mud that have fallen down the hillside where they can be stored until removed as a routine maintenance activity rather than an emergency response. Vegetation removal would occur in disturbed areas. Context-sensitive architectural treatment would be applied to the catchment basin. Construction access would be provided by temporarily closing the westbound lane and shoulder. Construction would be completed using temporary one-way reversing traffic control and shoulder closures. The proposed work is scheduled to begin in 2022. Approximately 30 working days would be required to complete the work.
Borrow and Disposal Sites
No borrow sites would be utilized. Excavated rock and soil would be disposed of at the Crocker disposal site, which has been previously approved for use as a disposal site. The Crocker disposal site is located on private property at post mile 38.96.
Staging/stockpiling of materials and equipment would occur along the shoulder of the eastbound lane within the project area.
The proposed work would be conducted within Caltrans’ right-of-way on federal land managed by the Klamath National Forest and would utilize a disposal site (the Crocker disposal site) that is located on private property. No right-of-way would be permanently acquired.
An underground fiber optic telephone line is present within the project area in the westbound shoulder and may need to be relocated to facilitate the proposed improvements.
Based on the current scope of work, no regulatory agency permits would be required. Work on federal land would require a Letter of Concurrence from the Forest Service for work occurring inside Caltrans’ right-of-way.
Caltrans has performed a review of resource records and databases and consulted with applicable agencies and individuals. Additional coordination with the Forest Service may be required for work proposed on federal land. Consultation with the Karuk Tribe is ongoing and will continue through project completion.