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!!f[Ji!lC1Y�lfA1YEN Mr. Charles Leubner r " 20 January 1997 Page 3 _�J On 19 December 1996, the contractor excavated the soil containing diesel leaked from the pipeline and stockpiled the soil on plastic sheeting near the Bus Shelter. The middle stockpile shown on Figure 2 near the Bus Shelter represents this soil (S9, S 10, S 11, S 12). The contractor used an -- organic vapor analyzer with a flame ionization detector (FID) to identify the soil around the tanks =; containing diesel product from the pipeline blowout. The contractor's screening method consisted of placing samples of soil in a plastic Ziplock bag and monitoring the headspace of the bag for the presence of organic vapors. No soil samples were collected of material screened by the contractor for laboratory analyses by the District (as represented by Helmick & Lerner Inc.) because the contractor agreed to arrange for the profiling and disposal of this material. =_ Soil excavated from the vicinity of the blowout that the contractor's screening indicated no impact by diesel was segregated into another stockpile as it was removed. That soil is shown in Figure 2 as =i the northern stockpile located near the Bus Shelter. The remainder of the soil removed from the -<= excavation was added to the stockpile adjacent to Tanks TS and T6. =1 The southern stockpile shown near the Bus Shelter on Figure 2 was from an area of stained soil which was overexcavated due to the presence of petroleum hydrocarbons detected in a soil sample collected from the northern end of Tank T7. Approximately 15 cubic yards of stained soil was excavated from this area on 24 December 1996. This material was segregated from the other soil -`' and is the southernmost stockpile shown near the Bus Shelter. Excavation and Stockpile Sampling Mr. Jerry Yoshioka was the San Joaquin County Environmental Health Division Inspector in -' attendance during the removal of the diesel tanks on 23 December 1996. Samples from the excavation floor and stockpiles were collected by Mr. Noel Lerner of Helmick & Lerner Inc. and were analyzed onsite by ExcelChem Environmental Labs in their State-certified mobile laboratory. Although water was present in the excavation due to the heavy rains which occurred during the weekend preceding the removal of the tanks, it was possible to obtained suitable samples of the native soil that were not saturated with water. The location of the samples and the depths from which they were collected are shown on Figure 3. ,. At the direction of the County, soil samples were collected from the floor of the tank excavations using a backhoe bucket. Soil samples collected for laboratory analysis were obtained from the backhoe bucket by scraping off the top several inches of soil with a steel trowel. A core sampler lined with a brass or stainless steel liner was driven into the soil using a slide-hammer to collect the sample. The liner was then removed from the core sampler and the ends of the liner were covered with sheets of aluminum foil and capped with snug-fitting plastic caps. The samples were labeled i with a unique sample number, date and time sampled, and delivered to the mobile laboratory.