PCB and Heavy Metal Soil Remediation, Former Boat Yard, South Dartmouth, Massachusetts

PCB and Heavy Metal Soil Remediation, Former Boat Yard, South Dartmouth Massachusetts. Michael E. Martin & Marc J. Richards, Tighe & Bond Consulting Engineers. Heavy metals have been added to marine paint for more than 100-years to protect boats from biological, chemical and physical degradation. Polychlorinated biphenyls (PCBs) were added to marine paint starting in the 1940’s to give the paint better adhesive properties and to provide anti-corrosion protection from moisture, chemicals and flames (approximately 2% composition of paint). The nature of the contamination at this project Site was primarily heavy metals and PCBs in soil and heavy metals in sediment. The source of soil contamination was from marine paint chips from repainting and maintenance activities conducted at the boatyard since the early 1900s. The source of sediment impacts is believed to be stormwater discharges to the Apponagansett Bay from routine boatyard activities, including power washing of boats. The overall goal of the soil remediation was to reduce PCB and metals exposure point concentrations at the Site to levels that do not pose a risk to human health and the environment. The work had to be conducted during the winter months, so the remedial and construction activities did not interfere with daily marina operations. This paper describes the remediation activities performed at the Site to achieve the overall remediation goal, which included: the chemical treatment of soil to stabilize the soil (bind leachable lead), excavation and off-site disposal of impacted soils and the construction of a multi-layer asphalt cap containment system to restrict access to residual PCBs and heavy metals. Additionally, this paper will discuss the applicable environmental regulations governing the remediation. As a measure to minimize the potential for future contamination, this project also included the construction of a boat wash/washwater collection system to prevent future paint chip debris from entering the environment.