Site CB001, which includes the Galena Aviation Vocational Technical Center (GAVTC) building (Building 61), is located in the eastern portion of the cantonment triangle area at the Galean airport south of the POL Tank Farm. The site is bordered to the north by Airport Road and the POL Tank Farm, to the west by the Frontier Flying Service Terminal, and to the south by the Galena Airport apron. From 1970 to 1997, Building 61 was used as an operational aircraft and storage hangar for Larry’s Flying Service, the U.S. Fish and Wildlife Service, Harold’s Air, Hageland Aviation, and Warbelow’s Air Service. In addition to the storage hangar, the building also housed a warm storage area, a passenger facility, and second-floor offices. An aircraft fuel pump was located approximately 30 feet east of the building’s northeast corner and was connected via a pipeline to two 5,000-gallon AVGAS ASTs. The AVGAS ASTs were located approximately 90 feet south of the former fill stand. One 500-gallon diesel AST was located near the AVGAS ASTs. Two 1,500-gallon heating fuel tanks were also on Site CB001; one at the northeast corner of the building and one at the southwest corner adjacent to a refrigerated storage shed. A 1,000-gallon buried sewage tank was located on the south side of the building. In 1997, the building was vacated, and remained vacant until 2000, when it was purchased by the City of Galena. The Galena School District converted the building into the GAVTC. In December 2002, Site CB001 was designated as a new Environmental Restoration Program site because of potential human health risks from benzene vapor intrusion into the GAVTC building. As a result, a remediation system consisting of a subsurface depressurization system (SSDS) and soil vapor extraction (SVE) system were installed in and adjacent to the GAVTC building in 2002. As part of a treatability study, six SVE wells were installed around the GAVTC building between 2003 and 2005. Soil gas from each SVE well was field tested for oxygen, carbon dioxide, hydrocarbon vapors, and lower explosive limit. In 2003, the exterior SVE wells at Site CB001 were connected to the SSDS to further mitigate vapor intrusion risks. The combined SSDS/SVE systems have operated nearly continuously since 2002. Beginning in September, 2013, a new ADEC approved sub-slab sampling and monitoring program was initiated to determine if the SSDS could be safely shut down without a buildup of benzene vapor. Sample concentrations after the initial SSDS shutdown test were well below cleanup thresholds. DEC approved seasonal operation for the SSDS in December 2013. The system will continue to be evaluated on a seasonal sampling schedule.