Soil Excavation at FT004
North Groundwater Treatment Plant
Fire Training Area #3 (FT004) covers about 30 acres in the northeastern part of the North/East/West Industrial Operable Unit. Waste fuel, oils, and solvents were burned at this site during fire training exercises between 1953 and 1962. The site is currently a vacant open field. Groundwater contamination consists of primarily TCE and its breakdown products as well as nickel. Dioxins, TPHs, and metals were detected in the soil, which posed potential human health and ecological risks.
Based on human health and ecological assessments of the potential risks posed by the contaminants, the North/East/West Industrial Operable Unit Groundwater Interim Record of Decision selected Extraction and Treatment for the groundwater, and the North/East/West Industrial Operable Unit Soil, Sediment, and Surface Water Record of Decision selected Excavation for the soil at this site.
A groundwater extraction system in place at FT004 pumped contaminated groundwater to the North Groundwater Treatment Plant (shown above) for treatment fro 2000 to 2009 as an interim remedy, in combination with a Monitored Natural Attenuation (MNA) assessment. The size and contaminant concentrations associated with the FT004 plume had decreased during the period of interim groundwater remediation. In 2014, the Travis Groundwater ROD selected MNA as the final groundwater remedy. The Site FT004 MNA monitoring network was established in 2015, and monitoring of the final groundwater remedy is ongoing. In 2015 a technology demonstration was initiated at the site. The technology demonstration will evaluate a total organic carbon dispersal method as a potential optimization approach for sites where enhanced reductive dechlorination is a component of the final groundwater remedy. The technology demonstration will be performed over a period of about four years and is expected to end in 2019.
In the summer of 2007, Travis AFB carried out a soil cleanup action at FT004. All of the contaminated soil was excavated and placed in a Corrective Action Management Unit (CAMU), located at site LF007. The soil cleanup action achieved residential cleanup levels for all chemicals of concern, so there are no Land Use Controls in place at the site. The results of the soil cleanup action are presented in a 2008 remedial action completion report.
During the 2007 soil excavation, TPH-stained soil was encountered. A data gap investigation to evaluate the nature and extent of the TPH contamination is planned for 2017. The data collected during the investigation will support a risk assessment to determine whether a soil cleanup action for TPH is necessary.