SITE INFORMATION AND CORRESPONDENCE

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potential presence of petroleum hydrocarbons from approximately 20 feet to the total depth of 60 feet bgs. The 30, 35, 40, and 45 foot soil samples from each of the wells was submitted for quantitative analysis of TPHg and benzene, toluene, ethylbenzene, and xylenes (BTEX) by EPA Methods 8015M and 8020 respectively. Each of the samples contained the requested analytes. The 40 foot bgs soil sample from MW-2 was the most impacted with laboratory reported concentrations of TPHg (880 mg/kg), and BTEX: 9.2, 45, 14, and 77 mg/kg respectively). In June 1991, GAS surveyed the wells relative to a temporary benchmark and measured the depth to groundwater. GAS measured product layers of 6.125 and 7.25 inches in MW-1 and MW-2 respectively. GAS did not report observing an immiscible layer on MW-3; but states that, "water samples were not collected for analysis." GAS reported that groundwater had dropped approximately five feet since 1988; and,-that the groundwater had a relatively flat gradient with a slight slope to the south. GAS concluded: * that offsite migration was a possibility; * the lateral extent of contamination was not yet determined, * the water bearing unit at 40 feet should allow recovery of the free product and/or dissolved contamination, * that a more northerly source may be contributing to the contamination; and, * that 3,000 to 4,000 gallons of gasoline were potentially present. Based on these conclusions, Falcon Energy extracted and removed several thousand gallons of impacted groundwater. In January 1994, San Joaquin County Health Services, Environmental Health Department (SJCEHD) requested that the wells be sampled to assess current groundwater conditions beneath the site. Dana Booth supervised the resurveying, (re) developing, and sampling of each of the three existing wells. On 7 March 1994 the following groundwater conditions existed beneath the site. * A product layer of 0.03 feet was measured at MW-3. * The water samples from MW-1 and MW-2 contained TPHg and BTEX well above established groundwater goals. * The groundwater gradient was calculated at 3.33 x 101 toward the southwest (using a 0.8 relative density for the product layer). Based on these results, Dana Booth recommended further assessment and remediation, and prepared a workplan (13 March 1994) proposing a next phase of work. On 22 July 1994, Dana Booth measured the depth to groundwater, and thickness of an immiscible layer (when present), at each of the existing three wells. * A product layer of 0.03 feet was measured at MW-3. * MW-1 recovered from purging at a rate less than 0.1 foot per hour; and therefore, was not sampled. * The water sample from MW-2 contained TPHg and BTEX well above established 2