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s KEI-J92-0205.R4 July 6, 1994 Page 6 largely of clayey slit underlain by apparently continuous layers of clay. The sand unit noted in the preceding paragraph may have an important role in the recharge of the uppermost aquifer underlying the site. WATER WELL SURVEY In an EMCON Associates (EMCON) report (dated November 30, 1989) prepared for adjacent sites undergoing environmental investiga- tions, reference is made to a well survey conducted by Woodward Clyde Consultants (Woodward Clyde) in 1984 . The well survey data was revised or amended in later Woodward Clyde reports in 1987 and 1989 . According to information contained in this well survey, no domestic water wells were located within one mile of the general area where the Unocal site is situated. In general, the quality of the shallow ground water is rated poor due to high sodium content. According to the EMCON report, the Woodward Clyde well survey also identified two wells that are located in the general area of the Stockton Port Terminal. These wells are 135 feet and 200 feet deep, respectively, and are used for landscaping and industrial purposes. Apparently, one of these wells have been observed to be . contaminated with oil since 1966, as recorded during Department of Water Resources (DWR) water level measurements. The screened interval of these two wells are apparently not given on the DWR sheets. The distances from the two wells to the Unocal site are not known to KEI. CONCLUSIONS PETROLEUM HYDROCARBON CONTAMINATION 1. Soil Contamination Delineation and Remediation Analytical results of the initial soil samples collected from the former fuel tank pit at the Unocal site indicated non- detectable concentrations of TPH as gasoline and BTEX for all samples, except for 2 .2 mg/kg of TPH as gasoline detected in sample SW2 , and O . o10 mg/kg of xylenes detected in sample SW4 (Figure 2) . TPH as diesel was non-detectable in all samples, except for samples SW2 and SW3 , which showed concentrations of TPH as diesel at 120 mg/kg and 2. 7 mg/kg, respectively. However, after additional excavation, the analytical results of soil samples SW2-A, SW2-B, SW2-C, and SW2-D (collected from the southeast sidewall of the tank pit) indicated non-detect- able concentrations of TPH as gasoline and BTEX. TPH as diesel concentrations ranged from non-detectable to 9 . 5 mg/kg. The results of the soil analyses are summarized in Table 6.