Foundation work is continuing at all five substructure locations on the suspension bridge over Carquinez Strait in Northern California. However, a 50-day delay stalled the work at tower two when crews encountered unexpected ruins of an old pier. The obstruction has been removed by using a crane-mounted oscillator to core through the debris and destroy it.
At tower two, crews have completed driving all 12 of the 3-meter-diameter by 51-meter-long foundation piles. The soil has been removed from inside the piles with a pile-top, reverse circulation drill. From the bottom of the pipe piling, crews are now drilling down another 43 meters to sock it into the rock. A mud-slurry system will be used to assist in pouring concrete into the rock. There will be 12 piles per tower.
Work is continuing on both anchorages. At the south anchorage, crews are driving steel pipe piling. Approximately 70 of the 360 piles required at this location have now been driven. At the north anchorage, excavation and shoring have begun. No piles will be driven at that end, and work is continuing on a retaining wall.
In the precasting yard, crews have completed construction of three precast footings for tower two. One was picked off the barge with a crane, and the other two were removed from the barge through a controlled sinking process. After the barge was sunk, the hollow precast footings floated in the water. They were then pushed with tugboats to Mare Island for storage. Approximately four miles away, the island is a former naval storage area. Meanwhile, the barge was refloated and returned to the casting yard where construction of the precast footing components for tower three has begun.