California Department of Transportation



Office of Geotechnical Design South 2

The Office of Geotechnical Design South 2 (OGDS2) provides expert soil and foundation recommendations for structures and highways throughout portions of the Southern Region of California. The Service Area for OGDS2 is comprised of Districts 8 and 11.

Abbas Abghari
Phone: (916) 227-7172
Fax: (916) 227-3321


Branch A

Angel Perez-Cobo

(916) 227-7167

Branch B

Mark DeSalvatore

(916) 227-5391

Branch C

Shawn Wei

(916) 227-5252

Branch D

Brian Hinman

(858) 467-4051


Geotechnical Liason

Tim Lam

(909) 383-7963



Erosion Remediation

At the request of District 8, the Office of Geotechnical Design - South 2 conducted a geotechnical investigation for State Route 330 for the purpose of providing recommendations to repair a heavily eroded slope. At this location, two-lane State Route 330 winds up a southerly descending ridge in steep heavily vegetated terrain. The site of the erosion corresponds with a 600 mm diameter corrugated metal pipe that terminates approximately 3 meters past the headwall/retaining wall. Over the years, discharge from the culvert has eroded the slope below the roadway which was at a slope ratio of 1:1. An erosion gully formed 9.1 meters deep directly below the guardrail/retaining wall and was approximately 30 meters wide at the widest point at the top of the slope. There is no shoulder on this section of roadway and erosion was undermining the guardrail retaining wall, making this a district priority to address.

The plan developed by the Office of Geotechnical Design South 2 and selected by District 8 was to rebuild the slope, replacing material that was lost with a steep, compacted fill using geosynthetic reinforcing. In addition, drainage was to be improved by rebuilding the cross drain, inlet structure and continuing the storm drain to the toe of the rebuilt slope. From 34.6 meters below the roadway in the erosion gully, the Contractor constructed a 9.1 meter tall, “wrapped face” wall with shotcrete cover with a batter of 8v:1h. From the top of the shotcrete wall, the slope continues up the hill about 28.5 meters (to relative elevation 103 meters) along a 1:1 slope ratio extending to within 1.6 meters of the guardrail at the top of the slope. The 1.6 meters between the guardrail and the top of slope is level to allow access for Maintenance forces.

Research Program

The Office of Geotechnical Design South 2 manages the Department’s geotechnical earthquake engineering research projects concerning including soil-structure interaction. Currently, the Center for Geotechnical Modeling at UC Davis is conducting a research project to study the effects of lateral loads due to soil lateral spreading during liquefaction on pile foundations utilizing the centrifuge modeling.