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i Former Beacon Station No. 474 May 15, 2000 Stockton California Results of Additional Subsurface Investigation monitoring wells MW-10 and MW-11, vapor extraction well VW-7 and air sparge well AS-1. Four-inch ID casing and screen was used for MW-12. A #3 sand filter pack was placed adjacent to and approximately two feet above the screened intervals. Approximately three feet of bentonite filter seal was placed on top of the filter pack. The remaining annular space was filled with a neat cement sanitary seal. The well heads were covered by traffic-rated vault boxes. Construction details for the monitoring wells are included in on the boring logs. A total of 103 soil samples were collected from the five soil borings as noted on the boring logs. Thirty-two soil samples were selected for chemical analysis and submitted to Kiff Analytical (Kiff) in Davis, California (Cert. #2236). The soil samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg), the volatile aromatic compounds benzene, toluene, ethylbenzene, and xylenes (BTEX) and methyl tertiary butyl ether (MTBE) by Environmental Protection Agency (EPA) Method 8260B. Twelve of the selected soil samples, generally collected from deeper intervals in the borings (65 to 112 feet bsg), were also analyzed for the seven fuel oxygenates MTBE, di-isopropyl ether (D1PE), ethyl-tertiary- butyl ether (ETRE), tertiary-amyl methyl ether (TAME) and tertiary butyl alcohol (TBA), methanol and ethanol by EPA Method 8260B. Soil analytical results, reported in milligrams per kilogram (parts per million or ppm), are summarized in Table 1. Analytical data reports are contained in Appendix D. Hydropunch groundwater samples were collected at depths of approximately 90 feet from soil borings B7, B8 and B9. The grab groundwater samples were analyzed for TPHg, BTEX, and the seven fuel oxygenates by EPA Method 8260B. Grab groundwater analytical results, reported in micrograms per liter(parts per billion or ppb) are summarized in Table 2. Four soil samples (SP-1 A,B,C,D) were collected from the cuttings stockpile generated during drilling of the soil borings. The stockpile samples were submitted to Kiff, composited into one sample and analyzed for TPHg, BTEX and the seven oxygenates by EPA Method 8260B, and lead by EPA Method 6010. Drill cuttings stockpile analytical results are summarized in Table 1. The drill cuttings were transported off site on November 11, 1999 by 1474.22rpt 5 HORIZON ENVIRONMENTAL INC.