AFS/Airport - TAR Possible Tar Pit Construction Area
Chemicals, Petroleum Product
Past Work on Site
The period during which the tar was disposed of at this site is unknown. The tar area was once included as “additional potential sources of contamination” for Site ST010 (Radian Corporation, March 1996, p. 3-121), though it was eventually identified as a separate site in the Preliminary Assessment report because it is west of the area of soil contamination resulting from the Site ST010 fuel spill and is associated with a separate source. The source of the tar is most likely excess tar from the nearby runway and from apron repaving and crack-repair activities from nearby road and/or runway. A site reconnaissance was conducted in September 2010. Multiple patches of tar were observed along the dike and runway. Damaged drums were also observed along the dike, some partially buried with others at ground surface. The patches of tar, which varied in size and ranged from a few feet wide to a maximum of 8 to 10 feet wide, were sometimes difficult to locate because of vegetation. Tar samples were analyzed for the specific carbon ranges of interest by ASTM D2887, as well as the following target analytes: PAHs, RCRA metals, and naphthalene. Specific carbon ranges of interest analysis, show light and heavy petroleum hydrocarbon fractions in samples TARPR001-PR (location TAR_PR001) and TARPR003-PR TAR (location TAR_PR003), collected near the dike, indicate a mixture of products. Results from sample TARPR002-PR (location TAR_PR002), collected near the runway, showed a heavy petroleum hydrocarbon fraction. Concentrations of target analytes within the tar do not exceed the RCRA Toxicity Characterization Levels. These results were presented at the TPT meeting held in February 2011. At that time, the USAF recommended moving from SI to no further action and non-qualifying site designation. A building permit request to remove the tar areas was submitted to the Alaska Department of Transportation (ADOT) on September 8, 2011. However, removal activities were not conducted in 2011 because of the requirement that removal occur at night, when the airport is shut down. Based on the report, the site inspection did not provide evidence that Site TAR is non-qualifying. The sampling has not demonstrated that the tar has not or could not impact soil above screening levels. 1- & 2-methylnaphthalene, benzo(a)anthracene and naphthalene were detected in the tar at concentrations above the migration to groundwater cleanup levels. When the tar at Site TAR is cleaned up, then soil samples from beneath tar removal locations should be collected and analyzed in accordance with the approved FSP.