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r i Quik Stop Market No 121 . CCI Project No 12118-3 Page 2 for chemical analysis The laboratory employed methods approved by the California Regional Water Quality Control Board (CRWQCB) and the EPA The groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg) and benzene, toluene, ethyl benzene and total xylenes (BTEX),using EPA Test Method 8015 and 8020 The samples were also analyzed for fuel oxygenates following EPA 8260 Test Method Summary of Laboratory Results Groundwater samples collected from the monitoring wells indicated two of the three wells (MW-1 and MW-3)to have detectable TPHg and BTEX contamination The laboratory reported monitoring well MW-3 to contain TPHg at 400 micrograms per liter (ug/1), 2 ug/l benzene, toluene at 3 ug/l, ethylbenzene at 0 8 ug/1 and total xylenes at 5 ug/l Monitoring well MW-1 was reported to have 58 ug/l TPHg and BTEX compounds at concentrations of 3 ug/1 or less No TPHg or BTEX compounds were detected in monitoring well MW-2 The laboratory also reported the three monitoring wells to be free of detectable methyl-t-butyl ether • (MTBE) No other fuel oxygenates were reported in any of the three wells The results of the groundwater analysis are summarized in Table 2 The analytical reports from North State and chain- of-custody documents are attached in Appendix B Discussion Groundwater measurements taken in the three onsite monitoring wells on October 18, 1999 indicated the depth-to-groundwater ranged from approximately 19 01 to 19 68 feet below the top of the well casings The water table has fallen approximately 3 feet since the July 1999 sample round Groundwater contours in the vicinity of the three monitoring wells indicate the groundwater flow direction to be toward the southeast, at a relatively flat gradient of approximately 0 002 foot per foot (Figure 2) The groundwater flow direction determined during this sample round is approximately same flow direction reported in COI's July 1999 quarterly monitoring report Groundwater samples collected during this quarterly sample round indicated two of the three onsite wells to contain relatively low concentrations of detectable TPHg and BTEX compounds No detectable MTBE or other fuel oxygenates were reported in any of the three monitoring wells this quarter This is a significant change for well MW-3, which was reported to have a concentration of 12,000 ug/l MTBE in the July 1999 sample round To date, monitoring well MW-3 has been reported to be free of detectable MTBE contamination two of the three quarters that the well has been installed Based on the data collected to date, no trend in the MTBE concentrations has been established for monitoring well MW-3 CCI recommends that the site continue to monitor on a quarterly bases to gather additional groundwater quality data at the site The next quarterly sample round is scheduled for January 2000