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Geological TeeWa inc. Page 4 GeoProbe Installation Report Cardoza(Louise) Project No. 1135.2 June 15,2004 Groundwater Sample Analyses - les analyzed contained contaminant concentrations None of the three groundwater samples' y above the laboratory reporting limits. Table 1 in Appendix A is a full summary of all soil and groundwater grab sample analytical data collected at the site. 3.2 Geology and Field Observations The following section discusses the subjective field observations and geology documented during this investigation based on the interpretations of the field geologist. • The site exhibits sand & clay geology. ❑ The sand units are typically brown at depths of five feet bgs and then change to lighter color_ at ten feet bgs and below. The sands range from very fine to very coarse; with some iron oxide staining. ❑ A clayey sand unit was encountered at depths ranging 20 - 24 feet bgs in GP-1 & GP-2. This unit was hard when compared to the loose sands above. ❑ Occasional loose sand and/or clay layers from 'h—2 inches thick were present in the clayey sand unit below 20 feet bgs. • No field evidence of contamination was noted during the investigation except for a trace OVM reading (l ppm; background 0 ppm) from the base of GP-2. This detection may have been ambient air carried from the active fuel dispenser areas.. • Groundwater was encountered during drilling at a depth of approximately 22 feet bgs based on drill rod observations. • The acid preservative in the vials reacted strongly with the groundwater when sampling. The production of gas made it difficult to preserve a zero headspace condition in the VOAs. See Appendix B, Boring Logs for more information. 4.0 CONCLUSIONS AND RECOMMENDATIONS Based on our interpretation of the data collected over` the course of this subsurface investigation, GTI have reached several conclusions. These conclusions are based on the premise that the data we considered, although incomplete, are representative of actual site conditions. We acknowledge that there may be undiscovered conditions, which would upon their consideration, change our interpretation and thus our conclusions. Our recommendations are based on our knowledge of site conditions, and on the state and limitations of subsurface investigative technology. 4.1 Conclusions • The field activities indicate that the trace MTBE detected in sample "D-3" is limited in extent. • None of the soil and groundwater samples contained contaminant concentrationsabove the laboratory reporting limits. There was no field evidence of contamination (odor or staining) and this supports the laboratory data in spite of the protocol problems. I L.r