Cracks had opened overnight in the wharf’s new concrete capping beam. The locations correlated to where cement was being mixed into backfill soils to stabilize them against earthquakes. An advanced survey robot established that sheetpile heads were moving near the mixing operation, and hardhat divers measured that the wharf face 20 feet deep had bulged out more than a foot. Atlas’ investigation proved that the wharf face was deforming because the fresh-mixed soil it retained was much weaker than the unmixed dumped soil. The wharf was unstable until time passed and the soil-cement hardened. Without changing the mixing procedure the entire structure could have failed out into the harbor.
Investigation & Discovery
We identified the correlation between concrete cracks and soil mixing work, collected data about displacements and soil-cement strength, and investigated alternative explanations. Time was of the essence; the work could not stop while we analyzed the problem. And with the site 17 hours ahead of our Santa Cruz headquarters, new data started arriving at midnight, making for some long days.
We supported HTBI in changing the soil cement design to space out the treatment locations, eliminate the need for overlapping treatment, and make equitable adjustments in the contract cost and schedule. The cumulative changes achieved a good outcome for both the US Navy and our customer, HTBI.
The Big Picture
This was a multi-million dollar problem that HTBI didn’t cause, but that nevertheless could have severely damaged their relationship with an important client—the US Navy. We corrected the problem, secured buy-in from the Navy and their engineer, and kept the project moving forward to an acceptable technical, cost, and schedule conclusion. What could have been a huge problem, possibly even a disaster, converted into a locally-negotiated change order with both parties satisfied in the outcome. Healy Tibbitts’ president called us after finishing the change order negotiations to share the good news.