FAA Fort Yukon Quarters Facility Bldg 100 UST 9-C-7
Past Work on Site
One underground storage tank was removed at this residence in 1995 as documented in the Fuel Storage Tank Decommissioning Assessments, dated 1995. Tank 9-C-7 was a 500 gallon heating oil tank that was removed along with 20 cubic yards of petroleum-contaminated soil. Five (5) confirmation samples were collected and analytical results showed that diesel-range organics concentrations up to 10,000 milligrams per kilogram (mg/kg) remained in soil at the site. During the 1996 Remedial Investigation, three (3) borings were advanced, one (1) of which was completed as a monitoring well. Diesel-range organics was found at a concentration of 4000 mg/kg in soil and 3 milligrams per liter (mg/l) in the groundwater. Benzene was found at a concentration of 44 ug/l in the groundwater. At that time, it was estimated that 20-40 cubic yards of petroleum contaminated soil remained in place. An air sparging/vapor extraction system was installed in 1996 as described in the Remedial System Installation and Monitoring Report, dated 1996. The system operated for several years and multiple Operation and Monitoring Reports were drafted with sample results and system operation evaluations. The system was turned off in April 2001, however monitoring continued throughout 2001. In November 2001, diesel-range organics concentrations in the groundwater continued to exceed the cleanup levels with a sampling result of 140 mg/l, whereas the benzene concentrations were below the cleanup level. Soil samples collected in August 2001 contained diesel-range organics concentrations of 11,000 mg/kg present at 12 feet below ground surface.