UST 1859 was a 27,000-gallon fuel oil tank (likely heating oil) associated with a possible 3-inch diameter pipeline regulated at Valve Pit "B". Precise details related to the UST are not clear from the site history and limited records exist. Updated December 2014: Based on data collected during the SI/SC investigations, the sources of contamination at Site UST1859 are confirmed to be releases from the former UST. Contamination in subsurface soils and groundwater from the UST occurred either from leaks in the storage tank or during tank filling. The apparent source area for Site UST1859, defined by concentrations of COIs that exceed extent soil SLs, is located near the suspected location of the former UST. It is possible the source area extends under Buildings 1858 and 1859. The contamination extends to depths of approximately 35 feet bgs. Site UST1859 was renamed CST014 by AFCEC in 2014. An addendum SC report was approved for Site UST1859 (CST014) on November 24, 2014. The purpose of this addendum was to address the remaining requirements for an SC Report under 18 AAC 75.335(c) (ADEC, 2012), specifically, to propose cleanup levels and remediation techniques for the site. Subsurface aeration of the soil and groundwater was the primary proposed cleanup technique, though several remedial techniques were retained for further evaluation in the cleanup plan.