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SI r� • Fourth Quarter 2003 Monitoring Report Quik Stop Market No 121 Page 3 Monitoring well MW-5, located on the southwest side of the Quik Stop Market was also reported to be free of detectable TPHg/BTEX and fuel oxygenate compounds this quarter One of the three deep wells, MW-10, screened from 65 to 75 feet within the B-aquifer, was reported to be free of detectable TPHg/BTEX and fuel oxygenate compounds this quarter Monitoring well MW-9 was reported by the laboratory to contain 96 ug/L TPHg this quarter Monitoring well MW-6 was reported to contain 16 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 well RW-1, summarizing MTBE concentrations over time, is 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 seven shallow A-aquifer wells this quarter, indicated the depth-to-groundwater ranged from approximately 23 50 to 24 30 feet below the top of the well casings The water level in monitoring well MW-4 was measured at 23 58 feet below the top of . the well casing The water table in the A-aquifer has dropped approximately 1 5 feet during the last three months The groundwater table at the site is essentially flat, with a slight depress area near monitoring well RW-1 and slight flow direction to the west toward well MW-12 (Figure 4) Groundwater measurements taken in the three B-aquifer wells indicated the depth-to- groundwater ranged from approximately 26 17 to 27 88 feet below the top of the well casings The water table in the B-aquifer has risen approximately 3 feet during the last three months A groundwater gradient map for the B-aquifer was created and indicates a gradient of 0 008 feet per foot to the northeast (Figure 5) No D O readings were collected this quarter due to a inoperable meter However, D O levels are summarized in Table 3 showing D O reading from previous sample rounds Based on the groundwater data obtained during the quarter, it appears the MTBE and TPHg concentrations have decrease significantly in virtually all of the site wells The TPHg and MTBE plume has been reduced to the immediate area around the fuel tanks The MTBE concentrations reported in well RW-1 have dropped from 160,000 ug/L on August 16, 2002 to a current concentration of 1,700 ug/L The TPHg concentration in well RW-1 has also decreased significantly since the System began operation The MTBE concentration in MW-4 has dropped from 15,000 ug/L on August 16, 2002 to non detect No MTBE was detected in two of the three B-aquifer wells Monitoring well MW-6 was reported to have very minor (1 6 ug/L) MTBE this quarter, and MW-9 was reported to have 96 ug/L TPHg A summary of the data collected during the operation of the System is presented in Table 3