California Department of Transportation



Office of Geotechnical Design North

The Office of Geotechnical Design North (OGDN) provides expert Soils, Rock, and Foundations recommendations for structures and Roadways throughout the Northern and Central Portions of California. The Service Area for OGDN is comprised of Districts 1, 2, 3, 5, 6, 9, and 10.

Traci Menard
Phone: (916) 227-1075
Fax: (916) 227-7150


Districts 1,2,3 (Structures)

Reid Buell

(916) 227-1012

Districts 1,2 (Roadway)

Charlie Narwold

(707) 445-6036

Districts 3 (Roadway) & 6,9,10

Reza Mahallati

(916) 227-1033

District 5

Ryan Turner

(805) 549-3750


Engineering Geology




Seismic Specialist

Qiang (John) Huang

(916) 227-1037

Geotechnical Engineering

Ron Richman

(805) 549-3385

Geotechnical Engineering John O'Leary (916) 227-1001 (M,T,F) (510) 286-4823 (W,Th)


Districts: Please utilize the below form to request geotechnical services in the North and Central Regions of California. Email the request form to

Office of Geotechnical Design North Services Request Form

Structure Design: Please follow procedures outlined in Memo to Designers 1-35 and email requests to


Antlers Bridge Project

The Antlers Bridge Replacement is located on Interstate 5 crossing over the Sacramento River arm of Shasta Lake. The new bridge will replacing a deteriorating bridge and modify the centerline alignment of the freeway to improve the radii of the two curves immediately south of the structure. The new structure will include two northbound and three southbound lanes. The proposed design for the piers of the new structure is lowering permanent steel casing through the water and soil, embedding the steel into the top of rock. A large diameter rock socket will then be drilled to provide the capacity for the piles with very high loads.

GS involvement includes drilling, sampling and testing of the subsurface materials; geophysical testing of the bore holes; analysis of foundation conditions, preparation of reports for the foundations, assessment of cuts to the approaches to the bridge.

Existing Bridge:
Existing Bridge of Antlers

Planned Bridge:
Planned Bridge of Antlers Bridge

Confusion Hill Bypass

The Confusion Hill Bypass Project is located on the U.S. Route 101 just north of Leggett between PM 98.5 and PM 100.9 in northwestern Mendocino County, California. The purpose of the $65M project is to relocate the alignment of U.S. Route 101 in order to bypass a major active landslide on the current alignment. Numerous closures during the winter of 2005/2006 as well as in previous years were due to slide activity at this location, resulting in significant disruption of transportation along the North Coast.

The Office of Geotechnical Design North, Branches A and B provide a Geotechnical Design Report (GDR) and a Foundation Reports (FR) for this project which involves construction of two bridges across the South Fork Eel River, a 250 foot tall cast in place segmental construction bridge on the south end and a 150 foot tall slant leg box beam bridge on the north end, two soldier pile tieback walls, and a tire derived aggregate lightweight fill over the existing Red Mountain Creek Arch Culvert on the north end of the project, as well as construction support.

The Geotechnical Investigation for this project consisted of 18 rotary core borings, extensive geologic mapping along the new alignment and 16 seismic refraction surveys, soil and rock testing and preparation of log of test borings. These important functions were provided by the Offices of Drilling Services and Geotechnical Support. These offices also contribute to support work during construction.

Ferguson Rockslide Restoration

At the end of May 2006 rockfall from the toe of the Ferguson Landslide buried State Route 140 (see the attached photo). This section of the highway is in the Merced River Canyon just west of Yosemite National Park. The base of the slide is over 200 feet above the roadway. Continued rockfalls made it impossible to re-establish the roadway on the existing alignment. Two temporary bridges and the abandon rail grade on the other side of the river were used to construct a bypass around the slide. A tight 90-degree turn at the downstream bridge required that traffic be restricted to a maximum vehicle length of 28 feet. The one-way signal controlled detour was opened in mid-August 2006. The Office of Geotechnical Design – North (OGDN) assisted D10 with slide management issues and detour construction.

OGDN is currently providing input on the five alternatives that are being considered for the permanent highway restoration project at this site (see the plan below). Two of the alternatives, E and R, restore the roadway on the existing highway alignment. Alternative E would remove the slide and stabilize the slope above the highway. Alternative R would consist of constructing a rock shed to protect the road from rockfalls generated from the slide. Alternatives S, C, and T will relocate the highway to avoid the slide, these alternatives will include a double bridge crossing of the Merced River. Alternative S will include a structure, either retaining wall or viaduct, that hugs the slope to minimize cuts and fills. Alternative C will include a cut through the hillside to connect the two bridges. Alternative T will include a tunnel that connects the bridges.

Landslide buried State Route 140

The plan of five alternatives that are being considered for the permanent highway restoration project

Gaviota Pass Debris Flow Mitigation

In June 2004 a wild fire burned through the Gaviota Pass area in Santa Barbara County. During the fire many drainages were denuded and the soils were baked making the slopes highly susceptible to debris flows. With the potential for severe winter rains Geotechnical Design –North assisted District 5 in investigating solutions for debris flow mitigations in the burn area. One solution was to install DEBRIS FLOW BARRIERS in several drainages that discharged onto the highway corridor. Between Oct 14 and Nov 5, 2004 Caltrans installed a 28 ft wide by 10 foot high barrier, referred to as the “North Barrier”, across a drainage channel that discharged onto the Highway.

In December 2004 several storms cycles passed through the area. With each storm local storm cells produced high intensity short duration rainfall. Within 12 hours of each storm debris flows developed.

At the North Barrier location approximately 300 cubic yards of debris impacted the barrier. All of the debris was contained within the system. Between storms the barrier was cleaned. Similar impacts occurred throughout the winter of 2004/2005 preventing any debris from reaching the traveled way.

Gaviota PassDebris Flow Mitigation 1

Gaviota PassDebris Flow Mitigation 2