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• Quik Stop Market No 121 CCI Project No 12118-2 Page 4 southwest side of the store The System began operating full-time on August 2, 2002 It has 10 valves (one for each sparge well) and is currently configured to run 18 cycles per day at pressures ranging from 24 to 34 PSI, with each cycle lasting 126 minutes During each cycle, the System switches among the 10 sparge wells Total run time for each sparge well is 7 minutes per each cycle At this time, each well is being injected with approximately 4 12 grams of ozone per day Discussion As stated previously, CCI has been monitoring the System's operation and site conditions by sampling the site wells twice during August and again for the quarterly report on October 8, 2002 CCI measured groundwater parameters for dissolved oxygen (D O ), temperature, pH and conductivity Groundwater measurements taken in seven of the shallow A-aquifer wells on August 8, 2002, indicated the depth-to-groundwater ranged from approximately 22 14 to 23 44 feet below the top of the well casings The water level in monitoring well MW-4 was measured at 22 79 feet below the top of the well casing The water table in the shallow A-aquifer has dropped approximately 2 feet during the last three months Groundwater contours in the A-aquifer monitoring wells indicate there is a slight gradient, ranging from 0 003 to 0 009 feet per foot, toward the northeast (Figure 4) Groundwater measurements taken in the three B-aquifer wells indicated the depth-to- groundwater ranged from approximately 25 23 to 26 58 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, probably from a reduction in groundwater pumping A groundwater gradient map for the B- aquifer was created and indicates a gradient of 0 013 feet per foot to the southwest (Figure 5) CCI collected background D O readings on July 31, 2002 The D O readings at that time ranged from 2 92 ug/L in RW-1 to 5 43 ug/L at MW-I 1 Since the System was activated in early August, the D O levels have increased significantly in nearly all the wells The D O levels are summarized in Table 3 Based on the groundwater data obtained from July 2, 2002 to October 8, 2002, it appears the MTBE and TPHg concentrations have begun to decrease in some of the site wells The MTBE concentrations reported in well RW-1 have dropped from 160,000 ug/L on August 16, 2002 to 89,000 ug/L on October 8, 2002 The MTBE concentrations have also decreased in MW-3, from . 130,000 ug/L on July 2, 2002 to 96,000 ug/L on October 8, 2002 The TPHg concentration in wells RW-1 and MW-3 have also decreased significantly since the System began operation