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4.2 Analytical Results The Kwikee water samples were analyzed for Total Petroleum Hydrocarbons as gasoline using EPA method 8015, for volatile aromatic hydrocarbons (benzene, toluene, ethyibenzene,and xylene) using EPA method 8020, and for gasoline oxygenates using EPA method 8260. The results are shown in Table 2. Samples from KF-I and KF-2 continue to be below reporting limits for gasoline and volatile aromatic hydrocarbons. MTBE has been detected in KF-2 for the past five quarters, and except for one quarter has been stable at a concentration of 0.850.97 µg/I (parts per billion--ppb). This is well below the accepted taste and odor threshold of 14 ppb. The concentration of TPH-g in KF-3 rose from 230 ppb in February to 470 ppb in May. This amount of increase is a common occurrence, as shown in Figure 4. This graph illustrates that there has been a major drop in the TPH-g concentration in KF-3 since December of 2000, and since then the concentration has declined gradually. If the decline continues at this rate, the trend line suggests that the concentration will reach.the non-detect level (50 ppb) by the fourth quarter of this year. This prediction is supported by the BTEX data. Toluene and ethylbenzene reached the non-detect limit (0.005 ppb) in February 2001, and have remained near or below this limit for nine consecutive quarters. Although benzene and xylene increased slightly this quarter, they have declined significantly in the past two years and xylene has been below the detection limit twice. MTBE, on the other hand, has remained rather constant over the past two years. Perhaps MTBE is more resistant to the active remediation that is being performed at the adjacent Chevron site. As in KF-3, the TPH-g and benzene concentrations declined sharply in KF-5 after December 2000. These concentrations continued to decline in 2001, temporarily reaching the non-detect level by the end of that year. Since the beginning of 2002, however, the concentrations appear to have stabilized, as has the concentration of MTBE. None have changed significantly in the past year (Table 2). It is thus possible that concentrations in KF-3 will also stabilize, rather than continuing their present rate of decline. Figure 5 is a contour map of Total Petroleum Hydrocarbons in the gasoline range. It includes data provided by Gettler-Ryan -for the adjacent Chevron site. The gasoline distribution is basically unchanged from the past few quarters. Concentrations decrease eastward from Chevron MW-1 to MW-6 to KF-3, and the most reasonable interpretation continues to be that KF-3 and KF-5 are near the eastern edge of the Chevron plume. 5