SITE INFORMATION AND CORRESPONDENCE

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FILE PUBLIC HtALTH SERVICES SAN JOAQUIN COUNTY r. w ENVIRONMENTAL HEALTH DIVISION N, k Karen Furst, M.D., M.P.H., Health Officer c. - 304 East Weber Avenue, Third Floor • Stockton, CA 95202 209/468-3420 JAY L SINCLAIR APR 2 0 2000 SINCLAIR TRUCKING 3780 LINNE ROAD TRACY CA 95376 RE: Sinclair Trucking SITE CODE: 1916 3780 Linne Road Tracy CA 95376 San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has reviewed the Work Plan: Soil and Groundwater Investigation dated January 18, 2000 that was prepared and submitted by Geological Technics Inc. (GTI) on behalf of the above referenced site and has the following comments. Data collected to date from various investigations at this site indicate that petroleum hydrocarbon contamination has impacted both soil and groundwater. Soil contamination in the source area is documented to 9-feet below surface grade (bsg) and has not been defined vertically. Soil contamination in boring S13-1, located approximately 30-feet southeast of the source area is documented at 11.5-feet bsg, and also has not been defined vertically. Soil contamination in boring MW-4, located approximately 30-feet east/northeast of the source area is documented at 14-feet bsg, and was non-detect at 24-foot bsg. Peripheral borings MW-2 and MW-3 were not sampled below 9-feet bsg. Groundwater contamination has been documented in the source area in MW-1 (total depth 20-feet bsg), and to approximately 30-feet east/northeast of the source area in MW-4 (total depth 25-feet bsg). The vertical extent of the groundwater plume is not defined in these areas. The lateral extent of the shallow groundwater plume is not defined to the west, north or northeast of the source area. Peripheral wells MW-2 and MW-3 (total depth 20-feet bsg) have been reported as non-detect at each sampling event, indicating that the lateral extent of the shallow groundwater plume has been defined towards the south. As the responsible party to this site you were directed in a PHS/EHD correspondence dated December 8, 1999 to submit a work plan that, when implemented, would define the soil and groundwater plumes. The submitted work plan proposes to advance a series of 10 geoprobe push-point soil borings for the collection of soil and grab groundwater samples. The work plan states that "One soil sample from each borehole, collected at the top of the sand layer, will be submitted to the laboratory for analysis". A review of the boring logs from previous work at this site indicates that this described depth is between 10 and 15-feet bsg. The stated purpose of these borings is to define the lateral extent of the soil and groundwater contamination. While borings to this depth will provide information on the lateral extent of the shallow contaminant plumes, they cannot provide information on the vertical extent of either the soil or groundwater plume. A Division of San Joaquin County Health Care Services