The objective of this project is to demonstrate and validate the Sorbent Polymer Extraction and Remediation from Sediments (SPEARS) system as a low-cost, in situ remediation technology for polychlorinated biphenyl (PCB) contaminated sediments that can be deployed at various Department of Defense (DoD) sites. Remediation of PCB-contaminated sediments continues to represent a substantial financial liability for the DoD and other federal agencies. The SPEARS system can be deployed over varying site conditions. This project will use the South Basin at Hunters Point Naval Shipyard (HPNS) as an example deployment site. Portions of the South Basin have PCB contamination levels in excess of 5,000 micrograms per kilogram (μg/kg), and the remediation target for areas such as these would be less than 1,000 μg/kg.

The SPEARS system is a novel remediation technology that uses rigid polymer spikes with a hollow interior containing absolute ethanol. Although it is well established that certain polymers have an affinity for hydrophobic organic compounds such as PCBs, the team’s research has found that the inclusion of an ethanol interior increases polymer affinity for PCBs up to 2,500%, essentially turning the spikes into a PCB sponge. Initial short-term laboratory testing indicated a minimum spike radius of influence (ROI) of 2 inches, leading to an inter-spike distance of 3 inches (with larger ROIs anticipated during longer duration deployments). The extreme partitioning disequilibrium between the spike and the surrounding sediment/porewater environment serves as the thermodynamic driving force for the passive process of PCB desorption and migration from the sediment and subsequent absorption into the polymer and ethanol interior. Individual spikes are anchored to modular baseplates that can be adjacently placed in a grid-like pattern over a range of bathymetries and around large obstructions. Once cleanup goals are attained, the SPEARS baseplates are retrieved and the PCB-containing spikes and ethanol can be treated chemically to destroy the PCBs and can then be reused or disposed of (if required) at an appropriate waste facility. SPEARS has proven successful in laboratory and pilot-scale field applications. This project will demonstrate its effectiveness in larger scale deployments while generating cost and performance parameters. Project success will ultimately be based on the ability of SPEARS to meet site-specific remedial objectives.

SPEARS will provide the DoD with a low-cost, low-maintenance remediation method for PCB-contaminated sediments. It is predicted to save the Navy in excess of $25 million based on estimates that this technology can be implemented at more than half of the Navy’s 200+ sediment sites with PCB contamination. The costs of this technology are on par with current contaminant immobilization techniques (but eliminate the risk of future liability due to barrier failure or leaching) and are significantly lower than other PCB removal methods such as dredging. SPEARS can help DoD meet the Defense Environmental Restoration Program goals of achieving Response Complete at 95% of Installation Restoration sites by the end of FY 2021. (Anticipated Project Completion - 2019)