THE OPPORTUNITY
PS&S was approached to remediate Dredge Certification Unit (DCU) Area 2B, which is a 24,500-square-foot underwater area that is part of the 17-acre Former BICC Cables Site located in the City of Yonkers, Westchester County, New York. Polychlorinated Biphenyl (PCB) contamination of the Hudson River sediments beneath the Electronic Power Research Institute (EPRI) Building, including DCU Area 2B, required remediation under the New York State Department of Environmental Conservation (NYSDEC) Brownfield Cleanup Program. The Selected Remedy prescribed by NYSDEC’s Record of Decision (ROD) was sediment excavation and removal.
THE CHALLENGE
Since 2010, six attempts have been performed to comply with the ROD Selected Remedy. All six of those attempted removal methodologies have demonstrated to be economically and technically infeasible, due to a combination of factors such as unmanageable quantities of debris beneath the building, excessive turbidity, and soft sediments that caused heavy equipment to become trapped below the structure.
In 2013, DCU Area 2B sediment excavation was attempted employing Remote-Controlled Robotic Vacuum dredging equipment known as the “ScanCrawler.” The NYSDEC-approved productivity rate for removing the PCB-impacted material could not be achieved to as a result of limited visibility, loose debris and unsafe deployment and recovery efforts. Therefore, NYSDEC requested an Alternatives Analysis Report for selection of the final DCU Area 2B Remedy in November 2013.
THE PS&S SOLUTION
PS&S designed a multi-layer engineered Reactive Core Mat Sediment Cover System (SCS Remedy) as the optimal means for completing the remediation of DCU Area 2B, and received NYSDEC’s approval of this remedy in February 2014. PS&S implemented the SCS Remedy in the summer of 2014.
RELATED PROJECTS
DISCIPLINES INVOLVED
GEOTECHNICAL