ARCHIVED REPORTS XR0010228 - Laserfiche WebLink

Home Browse Search

Former Discovery Chevrolet March 20, 1998 Tracy. California Problem Ase men Re ort 2.0 SITE DESCRIPTION The subject site is a former automobile dealership located at 1615 11th Street in Tracy, California. The site property is located adjacent to the Southern Pacific railroad tracks, and approximately 0.2 mile north of the Lower Main Canal (Figure 1). The elevation of the site is approximately 44 feet above mean sea level (MSL). The site is owned by Thomas Nokes and was formerly occupied by Discovery Chevrolet and most recently by Tracy Chevrolet. Currently the site is unoccupied. Site facilities include an auto showroom, a sales office, and service bays. Locations of these facilities and other pertinent site features are shown on the Site Plan(Figure 2). 3.0 BACKGROUND We understand from information provided in previous reports that two 500-gallon gasoline USTs were removed from a common excavation, and one waste-oil UST was also removed from the site in April 1993 (UST Removal Table 1 in Appendix B), and that no USTs are known to remain at the site (GeoStrategies Inc., December 7, 1994, Preliminary Environmental Investigation and Evaluation). We understand from information supplied by SJC PHSIEHD that the gasoline UST excavation was backfilled with the excavated soil from the cavity and imported pea gravel. GeoStrategies indicated in their report that when the two gasoline USTs were removed, four soil samples were collected from the base of the excavation at a depth of approximately 9 to 10 feet. These soil samples were found to contain total petroleum hydrocarbons as gasoline (TPHg) at concentrations ranging from 920 to 4,400 parts per million (ppm). Groundwater was not encountered in the gasoline tank excavation. A soil sample collected from the base of the waste-oil UST cavity at 7.6 feet bsg indicated 31 ppm TPHg, 270 ppm total petroleum hydrocarbons as diesel (TPHd), and 0.18 ppm benzene. In addition, a sample was collected at 5.6 feet below the dispenser located inside the building. Benzene was detected at 0.88 3001-12.par 2 HORIZON ENVIRONMENTAL INC.