Project Big Bird consists of a single, 100-foot-tall logistics building in Tracy, California with a footprint of 824,000 square feet. The 5-story building includes four levels of 133,000 square foot robotics-occupied sorting floors above the ground floor, providing approximately 3.5 million square feet of industrial processing and storage space. The facility includes parking for more than 1,800 cars and 230 trailers, and provides access to 40 loading dock bays.
ENGEO performed a geotechnical evaluation of the site, which included deep borings, seismic CPTs, test pits, laboratory testing, and surface-wave geophysical testing to characterize the site. Based on our findings, the geotechnical challenges associated with the site included expansive near-surface soils, relatively soft soils within the upper 15 feet of the site, and proximity to the significant seismic activity of the Bay Area fault systems.
To mitigate the expansive soils, ENGEO provided recommendations for lime- and cement- treatment for the building slab and proposed roadways. Due to the high anticipated loads of the structure, ENGEO evaluated the potential for total and differential settlement, and worked with the design team to implement an array of approximately 3,700 vibro piers to increase the bearing capacity of the soft surficial soils and reduce the potential for settlement. Finally, to reduce the design seismic loads on the structure per the California Building Code (2019), ENGEO performed site-specific seismic hazard and site-response analyses, which saved an estimated $7M in structural reinforcement.