Located near State Route 237 in Milpitas, California, Bridge Point Silicon Valley is an industrial complex comprised of two (2) ground-up, concrete tilt-up structures, together totaling 722,000 s.f. on a 35-acre site. The project is near big employment hubs such as San Jose, Oakland, and San Francisco, and close to major Fortune 100 operations within the Bay Area.
Greg Woolway, vice president and Bay Area officer for Bridge Development, shared about the project, â€śWe didnâ€™t want this to be a traditional warehouse. We have really cool wood features on these buildings. They have a lot of glass and glazing. You normally donâ€™t see that with industrial.â€ť
Existing Soil Conditions
Due to the projectâ€™s close proximity to the San Francisco Bay, just north of San Jose, the existing project site contained high levels of alluvial soil, making it too insufficiently dense to support the loads of new construction. To remedy this, Oltmans worked with Hayward Baker to propose an effective ground-improvement method in lieu of traditional drilled piles. The team opted for dynamic compaction.
Dynamic compaction uses the energy from a falling weight in a predetermined grid pattern to improve granular soils and fills. In this two-part process, in order to compact granular soil, the first step requires a 27-ton weight to be dropped repeatedly from a height of 60 to 70 feet at regular intervals of 7 feet on center throughout the site. This method eliminates two to three feet of sediment. Then, a surcharge of 10 feet is completed to further compact the clay soil and eliminate an additional three to four inches of sediment.
January 2020 Construction Video
In the video linked below, two rigs are completing a wick-drain installation across the proposed site for Building 2, prior to moving west towards Building 1. They are followed by DDC rigs which drop 27 tons of weight repeatedly onto a 15-foot-by-15-foot grid during two passes. Next is an ironing pass, using a 10-ton weight, spaced out among a seven-foot by seven-foot grid. Upon completion, the site elevation is anticipated to settle approximately two feet by densifying the loose granular soils up to 15 to 20 feet deep. Following this process, the site will be surcharged, anticipating another three to four inches of settlement. Piezometers and settlement plates will be installed to track the progress.