Yosemite View Lodge Highway 140 Interim Embankment Stabilization

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The California Department of Transportation (Caltrans) proposes to undertake a Maintenance project in Mariposa County near the community of El Portal this coming Fall of 2006--during the low river flow period. The project would reinforce a large void that has developed in the river-right embankment of the Merced River below State Route 140 between Yosemite View Lodge and Crane Creek Bridge. River flows have eroded underneath the concreted rock slope protection and other fill material from the base of the highway 140 road embankment, creating a hole approximately five to six feet high. The void is sandwiched between two bedrock outcrops, and it extends under the concreted rock slope protection an average of 12 feet toward the highway, creating a large overhang. The missing material is causing some settling of the highway roadbed, and several significant cracks (both longitudinal and transverse) have developed in the highway pavement. This project is intended to prevent further erosion of the void and halt the localized deterioration of State Route 140.

The project would be constructed by pumping Gunite (Cement Slurry Material) downslope from the highway through a large hose; construction personnel stationed at the base of the slope would use this hose and an attached nozzle to shoot Gunite into the void, filling gaps between exposed boulders and slope material. The entire void would not be filled; the existing embankment material would simply be reinforced to prevent further erosion. The Gunite pump and any other construction vehicles would remain on the highway or highway shoulder, and would not be driven down the slope or into the river channel.

This project is intended as an interim solution to the existing erosion problem. A project to permanently repair the undermined concrete rock slope protection on Route 140 from the Crane Creek Bridge to 0.6 mile west of the Yosemite National Park boundary - the "Route 140 Slope Repair" (EA 10-0E800) - is planned for construction in 2010 or later.