ARCHIVED REPORTS_XR0005403 - Laserfiche WebLink

Home Browse Search

TANK CLOSURE REPORT—BEACON #474 -3- 3440 East Main Street Stockton, California AMV Project No. 19012.03 Soil samples collected from locations P-1 through P-4 contained TPHg concentrations of less than 1.0 to 5.6 milligrams per kilogram (mg/kg), respectively. Soil samples collected from locations P1-B through N-B contained TPHg concentrations of less than 1.0 to 37 mg/kg. Soil samples collected from locations SL-1 and SL-2 did not contain detectable concentrations of TPHg. 4.0 OVEREXCAVATION AND ADDITIONAL SOIL SAMPLING The site was visited on September 17 and 23, 1993, in order to perform overexcavation of the tank basin. Soil samples were collected in various locations as agreed upon by Messrs. Fox and Infurna (Figures 7 and 8). The overexcavation was performed by Walton Engineering. Soil samples were collected from locations selected to assess the vertical extent of hydrocarbon constituents in the soil underlying the site. The soil samples were submitted to a California-certified laboratory for analysis of BTEX and TPHg. Analytical results from the September 17 and 23, 1993, sampling events are compiled in Table 1. Copies of certified analytical reports are presented in Appendix B. A sample collected from the southeast corner of the former tank pit at location T5 (Figure 4) at a depth of 28.5 feet below grade contained TPHg concentrations of 1.1 mg/kg with detectable amounts of benzene (0.016 mg/kg), toluene (0.013 mg/kg), ethylbenzene (0.0067 mg/kg), and xylenes (0.055 mg/kg). After additional excavation, soil samples T10 through T14-C were collected from soil at 30 feet below ground surface. Samples collected on September 23, 1993, from 30 feet below grade did not contain detectable levels of TPHg; BTEX constituents were present in these soil samples at concentrations ranging from 0.12 to 0.010 mg/kg (Table 1). 5.0 STOCKPELED SOIL Soil that was removed during excavation of the tanks and product lines was stockpiled on site. Approximately 1,000 cubic yards of soil was generated between September 15, and 28, 1993. Four hundred cubic yards of soil were excavated before the underground storage tanks were removed, and approximately 600 cubic yards were removed.during the excavation of the tank pit and the former pump islands and overexcavation in these areas. Four soil samples for every 100 cubic yards of stockpiled soil were collected for analysis of BTEX and TPHg. Soil samples were collected from various locations as designated by Mr. Infurna (Figure 9). Each set of four samples was then submitted to a state-certified laboratory for compositing analysis. Analysis of samples collected from stockpiled soil on September 15, 23 and 28, 1993, indicated the presence of TPHg at concentrations ranging from less than 1.0 to 2,400 mg/kg. Portions of R.PTOtz ECD