Non-Time-Critical Removal Action (NTCRA) Summary—Grasse River, Massena, New York

In 1995, Alcoa Inc. (Alcoa) implemented a Non-Time-Critical Removal Action (NTCRA) at a localized area within the Grasse River Study Area (Massena, New York). The objective of the NTCRA was to remove the most upstream source of polychlorinated biphenyl (PCB)-containing sediment in the Grasse River, while obtaining site-specific data for use in developing remedial alternatives for the site. Approximately 2,600 cubic yards (cy) of sediments and 400 cy of boulders/debris were removed/dewatered and disposed from the 1-acre removal area. The targeted removal area was enclosed by a triple-tiered silt containment system to mitigate the escape of total suspended solids (TSS). Boulder removal operations occurred first using a long-stick excavator fitted with a specialized bucket. Sediments within the 1-acre area were subsequently dredged using an 8-foot horizontal auger dredge. In addition, a hand-held suction dredge was used to remove a relatively small amount of material from an isolated area adjacent to Outfall 001. Water column data collected both during and after the removal operations showed that, despite the containment system's ability to significantly reduce TSS levels, approximately 5 to 30 pounds of sediment-bound and soluble PCBs did escape from the containment area. Similarly, caged fish and spottail shiner studies indicated increases in PCB bioavailability during, and immediately following, the operations.