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Quartet- 2003 Report). A linear ridge was evident near Chevron MW-1, and there was a relatively steep gradient on both the east and west flanks of that ridge, indicating that groundwater was flowing both east and west from the area of MW-1. By August, this ridge was much more strongly developed and extended northeastward from MW-1 across the entire Kwikee Foods site. As figure 3 illustrates, the ridge is very narrow, implying that flow is strongly channelized to the northeast. The gradient along the ridge crest (channel axis) from MW-1 to KF-6 is 0.0022 ft/ft, but the gradient transverse to the ridge from MW-1 to MW-6 is 0.0076 ft/ft (approximately 3.5 times steeper). North of both sites, the contour spacing increases, implying that the gradient flattens and becomes more planar. From MW-9 to MW-11,the gradient is only 0.0012 ft/ft. The implication of the high groundwater table in the vicinity of the Chevron tank pit and MW-1 is that highly contaminated groundwater is likely flowing to areas of lower potentiometric head to the northwest, northeast, and southeast of MW-1. The expected result is an increase in hydrocarbon concentrations in Chevron MW-2, MW-7, and MW-6 and Kwikee KF-1, KF-2, KF-3, and possibly KF-5 and KF-6. 4.2 Analytical Results The Kwikee water samples were analyzed for Total Petroleum Hydrocarbons as gasoline (TPH-g) using EPA method 8015, for volatile aromatic hydrocarbons (benzene, toluene, ethylbenzene, and xylene [BTEX]) using EPA method 8020, and for gasoline oxygenates and 1,2-DCA using EPA method 8260. The results are shown in Table 2. The Chevron samples were analyzed for "TPH-g, BTEX, 1,2-DCA, EDB, and MTBE, but not for the other four oxygenates. The results are not . tabulated here, but the TPH-g and benzene data are shown on maps that are discussed in this section. Samples from KF-1 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 six quarters, and except for one quarter has been stable at a concentration of 0.85-0.97 gg/1 (parts per billion--ppb). This quarter the concentration declined slightly to 0.73 ppb. However, MTBE was detected in KF-1 at 0.9 ppb. MTBE had not been detected in this well since August of 1998. The concentration of TPH-g in KF-3 rose from 230 ppb in February to 470 ppb in May and was statistically unchanged in August at 480 ppb. Slight increases were observed in the toluene and ethylbenzene concentrations, and a larger increase occurred in the MTBE concentration (170 to 270 ppb). The concentration of another oxygenate, tertiary-butyl ether (TBA) also increased, from less than 10 ppb to 62 ppb. These results are in accord with the prediction made in section 4.1 from the groundwater elevation map. Benzene is the only analyte that declined, from 23 to 9.4 ppb. The TPH-g and benzene concentrations in KF-5 have been on the decline since the third quarter of 2000 (Table 2 and Figure 4). This trend reversed slightly during the first half of 2002, when the Chevron remediation system was inoperative for a few months, but was reinitiated in the latter half of the year after the system was restarted. MTBE is also declining, although at a slower rate. The 4 i