Developing a Remedy for a Large Complex Chlorinated Solvents Plume in a Fractured Rock Environment

This presentation will detail site characteristics important for development of a remedy at the Cayuga County Groundwater Contamination Site, which extends from Auburn, New York, 7 miles to the southwest to the village of Union Springs near Cayuga Lake. Understanding of these characteristics—groundwater flow, contaminant distribution within the system, and natural attenuation processes—informed development of the proposed remedy, including division of the site into four areas: the former industrial site and three downgradient areas. The remedy includes the ongoing remediation of the source, currently being conducted by the owner and NYSDEC, and remedial actions proposed by EPA for the three downgradient areas. For Area 1, closest to the source, enhanced anaerobic biodegradation is proposed. Monitored natural attenuation is proposed for Area 2, which extends southwest from Area 1, and for Area 3, which extends to Union Springs.

The site is underlain by a shale and carbonate fractured bedrock aquifer system. Past waste disposal practices at the source have caused high levels of volatile organic compound (VOC) contamination in groundwater underlying the facility and immediately downgradient. VOC concentrations decrease significantly downgradient of the former facility. To characterize the bedrock aquifer system, EPA worked closely with USGS. A series of multilevel wells were installed near the source area and downgradient towards Union Springs. Borehole geophysical tools were used to characterize the hydrogeology in these boreholes and to support design of the multilevel wells. The owner of the source area has also conducted extensive investigations, including monitoring well installation and characterization of biotic and abiotic degradation in the aquifer. EPA, the USGS, and the owner have shared data and coordinated groundwater level monitoring and sampling events.