Over the past seven years, a 400-foot segment of Matilija Canyon Road that climbs along the mountainside – 2.8 miles from the highway and near the hot springs – has been reduced to a single lane due to hillside erosion from storm damage. A steep cliff developed along the roadside that partially undermined the road. The County of Ventura recently hired two construction contractors to restore the road to two lanes and stabilize the hillside to prevent further erosion. The prime contractor was Granite Construction, of Santa Paula, supported by a specialty subcontractor, Geotechnical Stabilization, Inc. (GSI) of Sacramento; the project was headed by Glenn Derossett, Engineering Manager of VCPWA.
To reinforce the slope, the contractor drilled 70 20-foot rods called “soil nails” into the face of the cliff beneath the road, extending into the rock mountainside under the road. After these soil nails were placed, they protruded into the air for a few feet from the face of the cliff, and steel webbing was placed on the face of the cliff, held in place by these soil nails. Concrete was then sprayed onto the steel webbing and the soil nails, building out the cliff face by several feet and reclaiming the lost lane. A concrete barrier rail was placed at the outside edge of the road along the cliff.
The project cost $240,000 and took three weeks to complete in November 2013. The road was successfully widened back to two lanes and the slope face was reinforced to prevent future erosion. This roadside repair is expected to last at least 20 years.