SITE INFORMATION AND CORRESPONDENCE

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Diesel was detected in all eight groundwater samples collected from the Geoprobes High concentrations were found in GP-2, GP-3, and GP-5 (9,000, 29,000 and 38mg/1, respectively) located along the west and east sides of the aboveground tank enclosure. It should be noted that samples collected from GP-2 and GP-3 were obtained from open borings which may have allowed soil contaminated with diesel into the sample. Free product was visible in the groundwater samples from GP-2 and GP-3 during sample collection. The remaining Geoprobe groundwater sample concentrations were below 1.0 mg/l. GP4 was also less than 1.0 mg/1, however, MW-1 which is located near GP4 was recently observed to have free product. Based on these results, it appears the most significant diesel concentrations in groundwater exist in the immediate vicinity of the former excavation extending to the northwest and southeast. Soil concentrations of TPH appear to coincide with this footprint (as shown on Plate 2). Previous investigation at the site and data obtained from the facility to the south of Leprino Foods indicated a general groundwater gradient to the northeast. An attempt was made to measure groundwater levels through the Geoprobe pipes, however, readings could not be obtained because of the narrow diameter metal pipe. CONCLUSIONS The Geoprobe investigation suggests that concentrations of diesel in the soil above 100 mg/kg exist in the immediate vicinity of the former USTs/excavation at a depth of 9 to 10 feet. Geoprobe groundwater results indicate that free diesel exists in the groundwater near GP-2 and GP-3; possibly in the vicinity of GP-5; and although GP-4 did not encounter significant TPH concentrations in groundwater, adjacent well MW-1 has had free product. The estimated limits of TPH-impacted groundwater based solely upon the Geoprobe data is shown on Plate 2. These limits will be further reviewed once additional groundwater becomes available. RECOMMENDATIONS Based upon the Geoprobe investigation and interpretation described in the above paragraphs, three well locations have been selected (as shown on Plate 2) to provide additional groundwater characterization. These locations are based upon the following: Avoiding redundancy with existing wells. Downgradient evaluation of the plume. Some characterization of the lateral extent of the groundwater plume. Kleinfelder will proceed with the well installation portion of our workplan utilizing the revised well locations depicted in this report once written approval is received from both the CRWQCB and San Joaquin County Environmental Health Division. LIMITATIONS Kleinfelder has prepared this report in accordance with the generally accepted standard of care which exists in Central California at this time. It should be recognized that definition and evaluation of geologic and chemical subsurface conditions is difficult. Judgments leading to conclusions and recommendations are generally made with an incomplete knowledge of the 24-220176-E00/CR30-1 Page 2 of 3 January 5, 1994 Copyright 1994 Kleinfelder, Inc. KLEINFELDER 3077 Fite Circle, Sacramento, CA 95827 (916) 366-1701