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i CLEARWATER C h O L f I \ C Evrv,romm��tu! Services 4 0 RESULTS 4.1 Water Level Gauging Data On June 16, 1997, the depths to groundwater 1n the six monitoring wells ranged from 16 05 to 16 79 feet below the top of casing Groundwater elevations, calculated for the purpose of estimating flow direction and gradient, were approximately one foot lower than groundwater elevations measured on March 21, 1997 The groundwater elevation contours shown on Figure 3 indicate that groundwater flow is toward the northwest The groundwater gradient was 0 008 foot/foot across most of the site, but was only 0 002 foot/foot between MW-1 and MW-6 This change in gradient appears as a flattening of the water table west of the former USTs, which is consistent with the configuration of the water table during previous gauging events On the basis of historic data, water levels at this site have risen approximately 12 feet within the past 3 to 4 years It should be noted that during second quarter groundwater sampling, well screens in all monitoring wells were submerged by groundwater r 4 2 Groundwater Analytical Results Results of MW-1 and MW-2 confirmation sampling indicated that the samples collected from these two wells on June 16, 1997 may have been switched during field work or laboratory handling Therefore, the analytical results discussed below pertain to the samples collected on July 9, 1997 from MW-1 and MW-2, and on June 15, 1997 for the other four monitoring wells TPHg and BTEX were not detected in concentrations exceeding the reporting limits in groundwater samples from monitoring wells MW-1, MW-4, MW-5 or MW-6 The sample from MW-3 contained MTBE at the reporting limit of 5 parts per billion (ppb), but none of the other analytes were detected in the sample The sample from MW-2 contained 66,000 ppb TPHg and 220 ppb benzene MTBE was not detected in the MW-2 sample, the detection limit for MTBE in this sample was elevated to 500 ppb because of the high concentrations of other target compounds A summary of groundwater elevations and analytical results is presented on Table 1 Hydrocarbon concentrations are presented graphically on Figure 4 Copies of the laboratory report and chain-of-custody form are attached as Appendix B D-101 1Q97 3 July 23, 1997