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1 f 4 _ Second-Quarter 2004 Monitoring Report Quik Stop Market No 121 Page 3 aquifer, were reported to be free of detectable TPHg/BTEX and fuel oxygenate compounds Monitoring well MW-6 was reported by the laboratory to be free of detectable TPHg/BTEX, and was reported to contain 15 ug/L MTBE No other fuel oxygenates were detected in any of the three deep wells The results of the groundwater analysis are summarized in Table 2 A graph for wells RW-1 and MW-3, summarizing MTBE concentrations over time, are also presented herein The analytical reports from STL, chain-of-custody documents and field notes are attached in Appendix B Discussion Groundwater measurements taken in the ten shallow A-aquifer wells this quarter indicated the depth-to-groundwater ranged from approximately 18 07 to 19 45 feet below the top of the well casings The water level in monitoring well MW-4 was measured at 18 52 feet below the top of the well casing The water table in the A-aquifer has risen approximately 2 feet during the last three months The groundwater table at the site is essentially flat, with slight flow directions to the north to northeast (Figure 3) Groundwater measurements taken in the three B-aquifer wells indicated the depth-to-groundwater ranged from approximately 2159 to 22 27 feet below the top of the well casings The water table in the B-aquifer has risen approximately 1 to 1 5 feet during the last three months A groundwater gradient map for the B-aquifer was created and indicates a gradient of 0 003 feet per foot to the southeast (Figure 4) Dissolved oxygen(D O ) readings were also collected this quarter, which ranged in the A-aquifer from 4 61 milligrams per liter(mg/L) in well MW-1 to 7 21 mg/L in MW-4 The D O reading s in the B-aquifer ranged from 3 89 mg/L in MW-6 to 4 15 mg/L in MW-10 The D O readings for all of the wells are summarized in Table 3 showing D O readings from previous sample rounds Based on the groundwater data obtained during the quarter, it appears TPHg and BTEX compounds have been eliminated from all of the site wells MTBE is "non-detect" in a majority of the site wells and continue to decrease in virtually all of the site wells with detectable concentrations The MTBE plume has been reduced to the immediate area around the fuel tanks The MTBE concentration reported in well RW-1 has dropped from 160,000 ug/L on August 16, 2002 to a current concentration of 12 ug/L The MTBE concentration in MW-3 has dropped from130,000 ug/L on July 2, 2002 to 0 90 ug/L No MTBE was detected m two of the three B- aquifer wells Monitoring well MW-6 was reported to have very minor (1 5 ug/L) MTBE this quarter A summary of the data collected during the operation of the System is presented in Table 3 In summary,No TPHg and BTEX compounds were detected in any of the site wells this quarter . Minor concentrations of MTBE remain in the shallow groundwater of the A-aquifer in the