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i DISCUSSION At the time of the first quarter monitoring event, groundwater was encountered in the monitoring wells screened within the upper zone (wells screened between 46 5 and 70 feet below ground surface [bgs]) at depths ranging from 48 81 to 50 40 feet bgs Well MW-3 is obstructed Groundwater was encountered in the monitoring wells screened within the lower zone (wells screened between 94 and 115 feet bgs) at depths ranging from 50 03 to 51 60 feet bgs Groundwater elevations increased approximately 0 01 to 0 16 feet in upper zone wells since the December 5, 2002, monitoring event In the lower zone wells, groundwater elevations increased 0 04 to 0 15 feet (except well MW-11, where groundwater decreased 0 66 feet) The groundwater flow direction on February 5, 2003, was calculated to be to the east at a gradient of 0 0013 ft/ft in the upper zone Since 1995, groundwater flow in the upper zone has consistently been toward the east and southeast A groundwater contour elevation map for the upper zone is shown on Figure 2 The depth to water measured in well MW-5 during this quarter appeared anomalous, therefore the well was not used in generating the groundwater contour elevation map In the lower zone, groundwater flow during the first quarter 2003 was toward the south at an average gradient of 0 008 ft/ft Groundwater flow in the lower zone has historically been toward the south and east A groundwater contour elevation map for the lower zone is shown on Figure 3 In the upper zone wells, THPG and BTEX were detected in wells VEW-1 and VEW-2 The highest TPHG concentration (130,000 pglL)was detected in VEW-2, and the highest benzene concentration (2,000 pg/L) was detected in well VEW-1 TPHG or benzene were not detected in the samples collected from upper zone wells MW-2, MW-4, MW-5, or MW-7 1,2-DCA was detected in wells MW-2 (86 µg/L) and MW-5 (8 5 µg/L) EDB was not detected in any of the upper zone wells In the lower zone wells, TPHG and BTEX were detected in wells MW-8 and MW-9 MTBE was detected In well MW-12 (0 76 µg/L) The highest concentrations of TPHG (190,000 pg/L) and benzene (20,000 µg/L) were detected in well MW-9 1,2-DCA was detected in wells MW-9 through MW-12 with the highest concentration (1,400 pg/L)detected in well MW-9 TBA was detected in wells MW-8 (65 pg/L)and MW-10 (11 µg/L) EDB was not detected in any of the lower zone wells TPHG, benzene, and MTBE concentrations for samples collected and analyzed during the first quarter 2003 are included on Figure 4 PHS/EHD has requested that all peaks detected in the analyses be reported A copy of the laboratory tentatively identified compounds (TIC) report is attached Tentatively identified compounds were reported for wells MW-8, MW-9, VEW-1, and VEW-2 Results of the TIC analysis are summarized in Table 3 ATTACHMENTS • Table 1 Groundwater Elevation and Analytical Summary • Table 2 Groundwater Analytical Results for Oxygenates • Table 3 Summary of TIC Analysis Results • Figure 1 Site Location Map • Figure 2 Groundwater Elevation Contour Map, Upper Water Bearing Zone (First Quarter 2003) • Figure 3 Groundwater Elevation Contour Map, Lower Water Bearing Zone (First Quarter 2003) • Figure 4 Groundwater Analytical Summary, (First Quarter 2003) • Appendix A Field Data Sheets • Appendix B Sampling and Analysis Procedures • Appendix C Certified Analytical Reports and Chain-of-Custody Documentation P\Apache P1asticslQuarterly reports120031Apache_1Q03 DOC 5TRATU5