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06 April 1999 AGE-NC Project No. 98-0460 Page 5 of 6 5.0. SUMMARY AND CONCLUSIONS Based upon observations and data collected from the site, AGE concludes the following: • TPH-d was detected in the three soil samples collected beneath the dispenser location at concentrations as high as 6,400 ppm. A low concentration of TPH-d was detected beneath the waste oil UST. The vertical and horizontal extent of impacted soil at the dispenser location have not been defined. • Petroleum hydrocarbons were not detected in samples collected beneath the diesel UST. ` • Total concentrations of nickel,zinc,chromium and cadmium detected in the sample collected beneath the waste oil UST were 67 ppm, 24.3 ppm, 12.75 ppm and 1.63 ppm, respectively. The detected concentrations are significantly below the State of California Total Threshhold Limit Concentrations (TTLCs) of 2,000 ppm, 5,000 ppm, 2,500 ppm and 100 ppm, respectively. Similar concentrations were detected in the sample collected from the soil r stockpile. • Lead,Chromium VI,PCBs and volatile organic compounds were not detected in the samples analyzed and are inferred to not be present at the site. • TPH-d was detected in two of the three soil stockpile samples at concentrations of 130 ppm and 655 ppm. • Ground water is estimated to occur at a depth of approximately 55 feet bsg at the site. 6.0. RECOMMENDATIONS Based upon data collected from the site, AGE recommends: • Preparation and execution of a work plan for the investigation of the vertical and horizontal extent of impacted soil below the former dispenser location. • Upon approval from the PHS-EHD, stockpiled soil should be spread on-site. A leaching potential analysis is included in Appendix C. 7.0. LIMITATIONS Our professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities. The findings were based upon field Advanced GeoEnvironmentsl,Inc. r