The U.S. Navy is taking a final step to remediate a 13-acre site within the former Hunters Point Naval Shipyard at Parcel B. This summer, the Navy is conducting what it expects to be the final round of groundwater treatment to address the last of the historic mercury contamination at Installation Restoration (IR) Site 26.

The contamination resulted from shipyard activities decades ago, when mercury was used to service ship components including scales, gauges, pumps, and anti-fouling hull paint.

For the past 30 years, the Navy has conducted numerous cleanup actions to address the mercury contamination. Workers have previously excavated and safely disposed of 12,100 cubic yards of contaminated soil - a volume of dirt that would leave a hole the size of a football field nearly seven feet deep. Residual mercury concentrations remaining in groundwater were further reduced using in situ groundwater treatment in 2017.

How the Cleanup Works

Environmental professionals are using drill rigs to inject a stabilization mixture into contaminated groundwater below the ground surface in a 2,000 square feet (0.05 acres) area. The stabilization mixture changes the mercury into a solid form of mercury so that it cannot leak or wash away.

The same method was successfully used in 2017 to reduce the footprint of the mercury contamination. However, due to the complex local geology, the stabilization mixture could not reach some localized underground pockets of mercury contaminated groundwater. This summer, the Navy is utilizing a specialized, high-precision drilling method to access and treat these remaining areas.

Checking the Work

To show the cleanup was successful in meeting the cleanup goals, qualified environmental scientists will sample and test the groundwater quarterly for two years to demonstrate the cleanup goals have been met before closing IR Site 26.

The Navy works closely with the U.S. Environmental Protection Agency (EPA), the California Department of Toxic Substances Control, the San Francisco Bay Regional Water Quality Control Board, and the San Francisco Department of Public Health at all phases of the cleanup process.