Tuesday, August 16, 2011

Stabilizing Slopes on the Angeles Crest Highway (SR-2)

The Station Fire, one of the worst fires in Los Angeles County's history, destroyed thousands acres of vegetation in the Angeles National Forest in August 2009. Many of the slopes were left bare of vegetation making them susceptible to mudslides and debris flows during heavy rains. During late 2009 and early 2010, heavy rains washed out several slopes including sections of the Angeles Crest Highway (SR-2).

To repair the highway we used several solutions, in some locations where the soil had to be stabilized Geotechnical Engineer Sam Sukiasian and Engineering Geologist Gustavo Ortega prescribed the use of geogrid. Geogrid is a plastic mesh material that acts like a root system where slopes are absent of plants.

To repair the washed out sections, construction crews compacted soil, then every two to three feet several yards of the geogrid was laid on top of the soil, and then the soil was compacted on top of the geogrid. For example, as pictured (April 2011) above, geogrid was used every three feet on a slope that was approximately 250 feet tall and 100 feet wide.