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i • • results were reported in the Second Quarter and Third Quarter Monitoring Reports In the second quarter, diesel contamination was again detected in the domestic well, but not in any of the monitor wells The domestic well was destroyed under the supervision of PHS/EHD during the third quarter, and only the three monitoring wells were sampled in that quarter Toluene was detected at a low concentration in TT-2 3.0 PROCEDURES Monitoring was performed on December 11, 1996 Upon arrival at the site, the wells were opened and allowed to equalize with atmosphenc pressure A Solinst water level meter was used to measure the depth to groundwater in the monitoring wells Depth measurements were recorded on the Well Monitor Report (Appendix A) and are shown in Table 1 After water depths were measured, a Grundfos Redi-flaw 2 submersible pump was used to purge the wells Approximately 20 gallons of water were pumped from each well and stored in plastic barrels During purging, a Coming pH, conductivity, temperature gauge was used to measure these parameters until they stabilized After purging each well, the pump was cleaned with a TSP/water solution After purging, new disposable bailers were used to collect samples from each well Two 40-m1 vials and one 1-liter amber bottle were collected and placed in a cooled ice chest and transported to Excelchem for analysis The laboratory report is included in Appendix B 4.0 RESULTS 4.1 Depth to Groundwater In wells TT-I and TT-2, the depth to groundwater has risen by about one foot since August 8 (Table 1) In TT-3, however, the depth is almost unchanged since August This is rather unusual, at most sites, all wells show similar trends from quarter to quarter 4.2 Groundwater Gradient During the first two quarters of 1996, the groundwater gradient was to the east In the third quarter, the gradient shifted to the south, and it remained so in the fourth quarter (Figure 3) At 0 0055 ft/ft, the gradient is slightly flatter than it was 4.3 Analytical Results The laboratory report is presented in Appendix B, and summarized in Table 2 No contaminants were detected in either TT-1 or TT-2, but diesel was reported in TT-3 for the first time The concentration of 69 ug/l (parts per billion) is very low and does not pose a health threat, but is somewhat surprising because TT-3 is nearly 40 feet upgradient from the former tank cavity Why 2 .