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, benzene at concentrations greater than the California MCL of 1 '� ug/L (Table 1.) . Groundwater sampled from MW4 since ,lune 1987 has contained levels of TPS as gasoline (or TVH) ranging from non-detectable to 300 ug/L. In the most recent sampling on 14 February 1990, the well did not contain sufficient water to be properly purged, and a sample of highly turbid water was collected (Appendix B) . Analysis of this sub-standard sample indicated that detectable 5 BTEX compounds were found in this well for the first time in 20 months. Low levels of these constituents ( Less than 3 ug/L) were found in the well in the 26 June 1987 sampling and again (up to 15 ug/L; 1 .5 ug/L benzene) in the sampling done on 14 February i 1990. Since the well could not be properly purged. before the l sample was collected, and the sample was very turbid, the 14`', February results may not be indicative of groundwater concen- tratians. Some contaminants may have been present in the sail particles in the water. Water sampled from MW5 since it was installed in 1987 show that ,. .. � no detectable concentrations of BTEX components have been found to datein groundwater from this well. The only petroleum contamination detected in water from MW5 was. in a sample } € collected .an 25 June 1987 which contained 4.2 .ug/L TVH (Table 1 this report, GTI. 1987 ), Since no detectable hydrocarbon contamination has been found in wells MW1 ; MW2, or MW5. for -a- period_of-approximately two years, E there Is evidence. that .the areas of the aquifer intercepted by. s these wells does not contain petroleum hydrocarbons. Since hydrocarbons were detected in water from these wells when they were first sampled more than two years ago, the fact. that con taminsation that..was once present is no longer present indicates ' contamination has diminished. ! that Lhe areal extent of . the e35/71050/2-90/tx 6 ; r ..