In August and September 2010, Arconic (formerly Alcoa) collected a number of sediment samples along both shores of the Grasse River from the Alcoa Bridge down to the St. Lawrence River confluence. All samples were collected in the near shore areas of the river, which are areas along the shoreline with less than 5 feet of water where potential exposures to sediment while wading are more likely. The sampling was done to better understand polychlorinated biphenyl (PCB) levels and determine the extent and depth of PCBs in the near shore areas so this information could be used in the development of long-term cleanup alternatives for the river. More than 180 locations were sampled in 2010 from the near shore areas, with more than 1,500 samples collected and submitted for PCB testing.
The attached maps provide the PCB results from this sampling effort, along with results from samples collected since 2003. The maps show the PCB concentrations found in the samples, which were taken at various depths in near shore areas. For ease of understanding, the colored shading along the shoreline shows the average PCB concentration for that area in the top three inches of sediment. The near shore individual sampling results are shown in the boxes. The boxes correspond to the sampling locations.
The 2002 human health risk assessment (available on this website) evaluated potential long-term risks associated with direct exposure (skin contact and accidental ingestion of sediments) to sediments containing PCBs. Based on this data, the 2002 human health risk assessment was updated to evaluate potential cancer risks and non-cancer health hazards associated with exposure to the near shore sediment at depths of less than 6 inches. The reassessment determined that based on the lower concentrations in sediment found in the recent sampling event, and the assessment of reasonable maximum exposures to young children (1 to 6 years), adolescents (7 to 18 years) and adults (18 years and older) who may recreate in these areas, the cancer risks are within the risk range used in making Superfund decisions and the non-cancer health hazards are below the reference level established by EPA. The depth intervals in this study were selected because direct contact exposures would normally only be a concern for the sediments close to the surface in the near shore areas.
The findings support the results of the 2002 health risk assessment, which indicated that the primary health concern associated with PCBs in the Grasse River is from consumption of PCB-containing fish and individuals are recommended to follow the fish consumption advisory found on the Health Advice on Eating Sportfish and Game by New York State Department of Health.
Click the links provided to download high or low resolution aerial photos of the Near Shore Sampling Maps. (High resolution maps are large and will require longer download times.)