This University of California Berkeley project site rests just north of Cal Memorial Stadium in the historic alignment of Strawberry Canyon and Strawberry Creek. The previous practice field was scheduled for upgrade with the addition of 2 levels of parking below. Three significant design challenges for the project include the Historic undocumented fill, two old culverts below the site, and the active Hayward fault just 100 feet to the east. The two active culverts beneath the site, the Little Inch (1920's construction) and the Big Inch (1940's construction), carry stream flow and flood overflow from the Strawberry Creek watershed. The Little Inch is a 4'x4' unreinforced concrete, box culvert with the invert at about 26 feet deep on the south end and about 46 feet deep on the north end of the site. The fill over this deeper culvert and the original Strawberry creek was placed at different times since the 1920's. The fill generally consists of soft to medium clay with varying amounts of gravel with native loose to medium dense, clayey gravel with sand, and alluvium and colluvium beneath the fill.
Farrell collaborated with the design team and contractor to provide a no-vibration, well-defined grout column, ground improvement system using Drill Displacement Column™ (DDC). DDC engineering and installation had to protect and preserve the historic culverts, support the new structure, and mitigate seismic compression and settlement of the fill. Farrell performed 3D analysis to optimize DDC support layout relative to the new foundations, the highly variable bedrock profile, and the Big and Little Inch culverts. Farrell's close collaboration with the structural and geotechnical engineers resulted in a DDC design that protected the Big and Little Inch culverts and provided the ground improvement for solid structural support.
Farrell installed over 600 DDC with 18" diameter full-displacement auger tools to depths of 10 to 48 feet to support the new parking garage and practice field. The project was successful and the Big Inch and Little Inch culverts were preserved with no damage.
Farrell Design-Build Inc. | Sacramento 530.621.4867 | Irvine 949.428.9596