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°" fr Second Quarter 2003 Monitoring Report Quik Stop Market No 121 Page 3 RW-1 and the fuel tanks, was reported to be free of detectable TPHg and BTEX compounds this quarter MW-3 was reported to have 13 ug/L MTBE Monitoring well MW-4, screened from 33 to 43 feet in the A-aquifer, was reported to contain 3 9 ug/L MTBE, and no detectable TPHg or BTEX compounds Monitoring well MW-8, located on the south side of the Quik Stop Market, was reported to be free of TPHg/BTEX compounds but contained 2 1 ug/L MTBE All three deep wells (B-aquifer), wells MW-6, MW-9 and MW-10, screened from 65 to 75 feet within the B-aquifer, were reported to be free of detectable TPHg/BTEX and fuel oxygenate compounds this quarter The results of the groundwater analysis are summarized in Table 2 Graphs for wells MW-3, MW-4 and RW-1, 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 17 45 to 18 79 feet below the top of the well . casings The water level in monitoring well MW-4 was measured at 17 62 feet below the top of the well casing The water table in the A-aquifer has risen approximately one foot during the last three months The groundwater table at the site is essentially flat, with a very slight gradient of 0 007 feet per foot to the northeast around well MW-5, and a slight gradient of 0 005 to 0 007 feet per foot to the northwest near monitoring well MW-1 (Figure 4) Groundwater measurements taken in the three B-aquifer wells indicated the depth-to- groundwater ranged from approximately 20 57 to 22 13 feet below the top of the well casings The water table in the B-aquifer has fallen approximately 2 feet during the last three months A groundwater gradient map for the B-aquifer was created and indicates a gradient of 0 006 feet per foot to the north (Figure 5) CCI also collected background dissolved oxygen(D O ) readings, which ranged from 3 46 ug/L in MW-5 to 9 61 ug/L in MW-4 Since the System was reactivated in early August, the D O levels have increased significantly in almost all the wells The D O levels are summarized in Table 3 Based on the groundwater data obtained during the quarter, it appears the MTBE and TPHg concentrations have decrease significantly in many of the site wells The MTBE concentrations reported in well RW-1 have dropped from 160,000 ug/L on August 16, 2002 to 15,000 ug/L on April 10, 2003 The MTBE concentrations have also decreased in MW-3, from 130,000 ug/L on July 2, 2002 to 13 ug/L on April 10, 2003 The TPHg concentration in well RW-1 has also decreased significantly since the System began operation The MTBE