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f 1 =�•.�—==so— _.L_ f 1 1 Resources well records, no domestic or potable water supply wells are located within one mule of the Greyhound facility SITE INVESTIGATION Soil Boring and Soil Sampling Procedures rIn January 1993, a total of four soil borings were advanced at the locations shown i on Figure 2 (Borings B-3, B-4, B-5, and B-6) to characterize the lateral and vertical r` = extent of hydrocarbon contamination at,the site. Each of the borings was advanced to depths between 45 and 46 feet using 4 25-inch inside-diameter hollow-stem augers and split-spoon sampling techniques in accordance with ASTM-Standard D-1586 Prior to advancing each boring, all downhole equipment was decontaminated by steam-cleaning. All drill cuttings were containerized in labelled DOT-approved, 55-gallon drums and left on site for proper disposal by Greyhound at a later date based on analytical results. Soil samples were collected in brass sample tubes at five-feet intervals and were logged by an experienced ES geologist, visually inspected for signs of staining and u screened for the presence of hydrocarbon odors and the evolution of organic vapors r with a photoionization detector (PID) Based upon PID readings, one soil sample per boring was selected for chemical analyses and sent to a State of California, Department of Health Services (DHS)-certified hazardous waste laboratory to be analyzed for 'r BTEX by EPA Method 8020 and TPHD by the DHS/LUFT Method (modified EPA Method 8015). Soil sampling protocol consisted of capping each end of the brass tube with teflon tape and non-reactive, plastic end caps The caps were then sealed with clear tape A chain-of-custody record accompanied each soil sample from selection and preparation r of the appropriate container at the laboratory, to the sample collection site in the field and back to the laboratory. Each sample was individually labeled, recorded in the field notebook, immediately packed in ice, and sealed inside an insulated shipping container r and shipped by overnight couner to the laboratory. The remaining portion of the split- spoon sample was used to describe subsurface materials Boring logs are presented in Appendix A Based on data collected, two geologic cross-sections of the site r stratigraphy were prepared. Cross section locations are shown on Figure 3. The cross- sections are included as Figures 4a and 4b. Groundwater Elevation Measurements During the supplemental site assessment activities, ch well was monitored for depth to water sing an electric water level indicator. Ndne of the wells were found to contain free✓product or hydrocarbon ,,sheens. In addition, groundwater level rmeasurements were made on January 20, 1993. Results are provided in Table 1 / ' These data indicate the hydraulic gradient across the site was approximately 0.003 feet per foot to the south ' ANALYTICAL RESULTS Soil samples collected for this site assessment were analyzed for BTEX and TPHD. TPHD analysis was performed using the DHS/LUFT-approved method (modified EPA EIS/SX356 05/0005 ', 3