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Soil samples were collected and analyzed from downgtadient Well Borings MW-DIS-2, 4 -3, -4, -5, -6, and -7S at depths between 55 feet and 75 feet bgs. BTEX and TPH-Gas I concentrations were nondetectable. Lead concentrations in the soil samples ranged from 1.34 to 11.5 mg/kg. These levels are within the range for background lead,concentrations and well below the California Total Threshold Limit Concentration (TTLC) for lead of 1,000 mg/kg. These results indicate that the soil contamination is largely restricted to the soil near the current water table elevation in a small area below the former tank pit. Since SB-DIS-3 is only 15 feet from SB-DIS-2, the area of contaminated soil is estimated to be approximately 20 feet in diameter (300 square feet). In order to determine the type of nutrients and non-oxygen electron acceptors available in the soil near the groundwater table, additional analyses were performed for soil samples collected from Boring MW-DIS-7S (Table 3-4). Both nitrate and phosphate, non-oxygen electron acceptors, were detected in each of three samples above detection limits. These data were collected to supplement the evaluation of remedial technologies discussed in Section 4. Groundwater Investigation Results The results of the groundwater investigation are presented on Table 3-5 and on Figure 3-7 and indicate that significant levels of BTEX, TPH-Gas, and lead exist in the groundwater beneath the former Disco property. Although high dissolved con- centrations of gasoline constituents exist in the groundwater beneath the former Disco tanks, no free product gasoline was ericountered in any of the Del Monte monitoring wells. Petroleum sheens were observed, however, on the surface of water extracted from Monitoring Well MW-DIS-1. The TPH concentrations in MW-DIS-1 are nearly equal to the sum of the BTEX compounds. These observations indicate that the contamination is largely dissolved; a nonaqueous phase is absent. Samples collected from Monitoring Wells MW-DIS-2, -3, and -7D contain dissolved BTEX. Monitoring well MW-DIS-7D is the furthest downgradient well in which BTEX I compounds were detectable. Table 3-6 presents -the results of a general mineral analysis performed on a groundwater sample collected from MW-DIS-1. The results indicate that the shallow groundwater is a calcium-bicarbonate type with high alkalinity and hardness. The water exceeds the secondary drinking-water standard for total dissolved solids (500 mgA), indicating a potential objectionable taste. I 1 f i SF031604\RP1006.51 3-12