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' r RIEDEL ENVIRONMENTAL SERVICES INC ' 4.2 Soil Sample Analyses The confirmation samples were relinquished to the State certified mobile laboratory operated by Argon, for on-site analysis. The nine confirmatory soil samples (EXP-01-1,-2c,-3; EXP-02-1,-2c,-3,and EXP-03-1,-2c,-3)were analyzed for total petroleum hydrocarbon as diesel (IPHd) by DHS/EPA Methods 3550/8015 and the fuel components benzene, toluene, ' ethylbenzene, and xylene (BTEX) by EPA Method 8020. The results of the on-site analytical testing indicated that detectable concentrations of TPHd or ' BTEX were not present in eight of the nine samples obtained from the bottom of the UST excavation. However, sample EXP-02-3 contained 2,900 ppm TPHd. Copies of the laboratory ' report sheets and the accompanying chain-of-custody document are provided in Appendix B. A summary of the soil sample analytical results are presented in Table 1. 1 5.0 OVER-EXCAVATION AND ADDITIONAL CONFIRMATORY SAMPLING 1 5.1 Over-Excavation On 11 November 1993, over-excavation of the bottom of the UST pit to a depth of 17.5 feet below grade was conducted by Aronson in the area from which soil sample EXP-02-3 had been obtained. A total of approximately 120 cubic yards of excavated soil was transported to Forward landfill in Manteca, California, in 6 truckloads by Valley Material Transportation. Approximately 20 cubic yards of the excavated soils, which contained greater concentrations of ' residual diesel fuel, were temporarily placed in the western end of the excavation. The 20 cubic yards of soil were subsequently loaded and transported (on 17 November 1994)in one truckload by Valley Material Transportation to the Gibson Environmental facility located in Bakersfield, ' California. Copies of the Non-Hazardous Waste Manifests and the Gibson Environmental Non-Hazardous Waste Data Form for the transportation and disposal of the soils are included in appendix A. 5.2 Second Confirmatory Soil Sampling and Analysis On 12 November 1993, RES and Pacific Bell personnel meet with Ms. Mary Meays, REHS of the Public Health Services of San Joaquin County to discuss and to formulate a sampling plan ' for the soils in the area of the over-excavation. A plan was developed and 8 soil samples were retrieved from the bottom of the excavation utilizing a manually operated slide Dammer sampling device. The samples were obtained approximately 2.5 feet below top of the tank tie-downs at ' a depth of approximately 17.5 feet below grade. All sample locations were determined by Ms. Linda Turkatte, REHS of the Public Health Services of San Joaquin County. The 8 samples were relinquished to Argon for on-site analysis. The confirmatory sample locations are shown ' on Figure 4. 4035-9315UT1pg sTOXN.RYMIMAR94 3