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09 March 1999 <br /> AGE-NC Project No. 98-0432 <br /> ' Page 6 of 7 <br /> 4.4. ANALYTICAL RESULTS OF WATER SAMPLES <br /> TPH-d and BTEX compounds were not detected in the two water samples analyzed from boring B 1 <br /> and 86. The oxygenated fuel additive MTBE was detected in both water samples analyzed.,MTBE <br /> was detected in the grab ground water samples collected from borings B1 and B6 at concentration <br /> of 4.3 micrograms per liter(µg/1)and 760µgll.No other fuel additives were detected in the analysis <br /> ' of the water samples. <br /> Analytical results of all water samples collected at the site are summarized on Tables 2. The <br /> laboratory report(PET Sample Nos. PE 3826-01 and 02), chain-of-custody forms-and QA/QC are <br /> included in Appendix B. <br /> 5.0. SUMMARY AND CONCLUSIONS <br /> ' Based on the data collected from the site, AGE finds: <br /> No petroleum hydrocarbons were detected in the soil sample analyzed from the boring <br /> ■ advanced on the site. However, the.highest concentrations of petroleum hydrocarbons as <br /> diesel in soil were detected in samples collected near central portion of the former diesel <br /> UST during removal of soil underlying the former USTs. The lack of detectable <br /> hydrocarbons vertically and laterally limits the extent of the petroleum release to the direct <br /> vicinity of the former UST excavation. <br /> ' AGE calculates that a approximately 93 gallons of diesel was removed in the soil excavated <br /> during the interim remediation on the site in September 1998. Appendix C presents the <br /> ' calculations.for the hydrocarbon-mass removed,based on analytical results from stockpile <br /> soil and'UST excavation floor samples... <br /> • A silt/clay layer appears to underlay the site at a depth of approximately 30 feet bsg. This <br /> ' layer is inter-bedded with sand units which are prevalent on the east and west edges of the <br /> former diesel UST location. <br /> ' Diesel and BTEX compounds were not detected in the grab ground water samples collected <br /> from the site. MTBE.was detected in both of the water samples collected. This concentration <br /> exceeds the State of California, Department of Health Services action level for MTBE in _ <br /> drinking water. <br /> Advanced GeoEnvironniental,Inc. <br />