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J III • Monitoring Well Installation Report—Former Unocal Station#0123,Tracy,CA January 17,2001 420 and 290 ppb, respectively, but the chemical analytical report (Appendix F) noted that these values were from discrete peaks The chromatograms showing the discrete peaks are in Appendix G At the request of GR, Mr Alan Kemp of Sequoia Analytical (ELAP #1271) reviewed the chromatograms In a telephone call with Mr Kemp on January 10, 2001, he stated that the discrete peaks were not caused by diesel, nor did any other type of petroleum hydrocarbons cause them He could not determine from available information what caused the peaks WASTE DISPOSAL Soil cuttings generated during drilling activities were placed in 55-gallon drums Approximately 0 7 yards of soil cuttings were removed from the site and taken to Forward Landfill in Manteca, California, for disposal A copy of the disposal confirmation form is included in Appendix B DISCUSSION TPHg, BTEX, 1,2-DCA, EDB, or oxygenates except methanol were not reported in any of the soil or groundwater samples Upon further review, Sequoia Analytical has indicated that the discrete peaks on chromatograms initially reported as diesel range hydrocarbons in groundwater were not caused by diesel, nor did any other type of petroleum hydrocarbons cause them Methanol was reported in a soil sample from well boring U-S at 21 feet bgs at a concentration of 195 ppm • Based on the results of this investigation, the dissolved hydrocarbon plume in groundwater beneath the subject site is delineated in the downgradient direction The results of this investigation also suggest that the elevated hydrocarbons reported from boring B-5, located at the northwest corner of 11 h Street and Central Avenue, are from a source other than the subject site (GR report 240073 03, Sail Boring Report, dated March 10, 2000) Additional investigation is not warranted, and this site should be considered for closure 24007305-1 g