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GT-1, implying that the groundwater flow direction is radial toward the low spot in the vicinity of GT-1 The hydraulic gradient between GT-5 and GT-1 is roughly 0 005 ft/ft, which is a fairly flat gradient Both the contour pattern and the gradient are very similar to the situation observed during the first quarter of 2003,when the gradient was 0 003 ft/ft to the south 3.3 Analytical Results Diesel was detected in three of the five monitoring wells (Table 2) The concentration rose slightly in GT-5 and declined slightly in GT-6 and GT-1 It was unchanged in GT-9 The changes are minor and are probably not indicative of any significant overall change in concentration However, it is interesting that the hydraulic gradient has apparently been away from GT-5 and GT-6 and toward GT-I for two consecutive quarters, but the TPH-d concentration has increased in GT-5 in that time and declined slightly in GT-6 and GT-1 It seems likely thgt the low gradient is not responsible for these minor changes in concentration - 4 0 CONCLUSIONS In the First Quarter 2003 Report we concluded that hydrocarbon concentrations have been stable for the past nine months This conclusion can now be extended to the past twelve months We also noted that no statistically significant difference in diesel concentrations was apparent in purged vs unpurged wells The data from the second quarter support that suggestion We have made a similar observation in previous years Concentrations in GT-3 (the nearest well to the former UST excavation) and in the Gillies domestic well (G-1) remain below the detection limit The concentration in GT-1 was also below the limit this quarter Hence, monitoring data continue to demonstrate that contaminant concentrations are very minor at this site, especially within the Modesto aquitard, and have remained low ever since the static water level dropped below the base of the Modesto Aquifer in late 1999 3