Problems/Comments

Eleven oil exploration wells were installed by the U.S. Navy (Navy) between 1945 and 1954. A number of investigative and removal actions (RA) were performed in Umiat to address contamination associated with the oil exploration wells abandoned by the Navy. The Test Well #9 site consists of the area of approximately 8000 square feet impacted by former well drilling activities resulting from polychlorinated biphenyls (PCBs) that were used as a tracer during well drilling and testing operations. Site investigations in 1997 and 1998 confirmed that soil was contaminated with diesel range organics (DRO), residual range organics (RRO), and PCBs up to 1100 mg/kg, among other contaminants of concern. Cleanup actions at the site from 2009 to 2014 resulted in the removal and off-site disposal of almost 10,000 cubic yards (15,000 tons) of PCB and petroleum contaminated soil from the Test Well 9 site (documented in Hazard ID 3093). The Test Well 9 Drainage Basin study area is approximately 55 acres, including the defined drainage channel positioned south and east, adjacent to the former Test Well 9 wellhead location and several smaller drainages branches that lead into a wetland area. Sediment samples collected from the drainage channel in 2011 and 2012 found PCBs above the cleanup level. Soil, sediment, and surface water samples were collected in 2015 and 2016 identified PCBs, DRO, and RRO above the cleanup level in soil and sediment, leading to the development of a risk assessment.

Action Information

Contaminant Information

Control Type

Requirements

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