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Roberts Oil Company May 23, 1988 Project No. 1628G Page 3 and benzene, toluene, and total xylenes (BTX) following the appropriate EPA methods. All samples were placed in a refrigerated chest and were transported under chain -of -custody documentation to a state -certified laboratory for chemical analysis. 4.0 ANALYTICAL RESULTS All three ground -water samples (MW -2, MW -3, MW -4), were analyzed for TVH, BTX, and TEH. Results of the analyses revealed no detectable concentrations of TVH or BTX in any of the samples. Ground -water sample results from wells MW -2 and MW -3 revealed no detectable concentrations of TEH; however, the results for the well MW -4 sample revealed a TEH concentration of 240 parts per billion (ppb). The results of the laboratory analyses are presented in Table 1. 5.0 DISCUSSION The ground -water surface as measured on March 31, 1988 is presented in Figure 2. The ground -water flow direction as shown is toward the southwest at an average calculated gradient of 0.0005 feet per foot. This flow direction is approximately 90 degrees different from the April, 1987 southeast direction reported by J.H. Kleinfelder and Associates (Kleinfelder, 1987). The most recent data indicates that the local ground -water surface has apparently changed over time. Due to the very low inclination of the ground -water surface, minor variations in water levels can drastically alter the apparent flow direction. Because the local ground -water surface is nearly flat the contamination migration is therefore surmised to be slow. These conditions make it difficult to determine the prevailing local ground -water flow direction. While no state action levels currently exist for TVH and TEH, the TEH value observed in well MW -4 and the free -product in well MW -1 indicate that the ground -water on site has been impacted.