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Mr Michael Collins 2 September 17, 1992 with clean imported fall The old tanks were transported by Triangle, Inc to their Sacramento, California facility for disposal Soil samples taken from the excavation had concentrations of total petroleum hydrocarbons as gasoline (TPH-G) ranging from non-detect (ND) to 460 parts per million (ppm); concentrations of benzene were all ND, concentrations of toluene, ethylbenzene, and xylenes ranged from ND to 15 ppm; ethylene dibromide (EDB) concentrations ranged from ND to 0 00065 ppm; and total lead concentrations were all ND Of the two soil samples collected beneath the pump islands, only one, the Pump-2 sample collected at 4 5 feet, had detectable concentrations The TPH-G concentration was 13,000 ppm and BTEX concentrations were 4 2, 56, 21 , and 160, respectively Soil Va or Survey The soil vapor survey was conducted on August 27, 1992 Prior to the start of the survey, the site was checked for underground utilities by Cruz Brothers Sub-surface Locators Any survey points falling in the path of an underground utility was moved to the nearest safe location The soil vapor survey was conducted by Environmental Control Associates and supervised by a Canonie site engineer The probes were inserted using a hydraulic ram and advanced to the depths of 9 and 15 feet Samples were taken using a charcoal tube connected to a constant flow sampling pump A known volume of air was pumped through the tube The tube was then capped and labeled with the site name, sample identification, depth, and time The sample tubes were then submitted to the mobile laboratory, extracted with methanol, and analyzed for TPH-G with a gas chromatograph/flame ionization detector (GC/FID) The reporting limit for TPH-G was 500 parts per billion volumetrically (PPBv) Following the removal of the soil-vapor probe the hole was backfill with neat cement grout Results of Soil Vapor Survey A total of 9 soil vapor survey points were sampled at two depths each The locations are shown in Figure 3 Based on the results, one soil vapor point (SG-7) was moved from its original location and an additional point (SG-9) was sampled Six samples showed detectable concentrations of TPH-G SG-1 at 9 feet at 25,000 PPBv, SG-2 at 9 and 15 feet at 11,000 and 1,700 PPBv respectively, SG-4 at 15 feet at 26,000 PPBv, SG-5 at 9 feet at 9,000 PPBv, and SG-6 at 15 feet at 600 PPBv A summary of soil vapor survey results are shown in Table 2 The analytical results are contained in Appendix A. These results indicate that the largest potential source probably is the northern pump island area PL1W191-6341reportslco1hns2 rpt [September 17, 19921 ® zwEnvlronmental