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4 I <br /> Geological Tecktrfrs!xc Page 5 <br /> Groundwater Monitoring Report <br /> Project No.425.2 <br /> October 19,2004 <br /> The lab results for the above analysis are summarized in Table 8 of Appendix A, and the <br /> ' laboratory data are presented in Appendix B. <br /> As required under AB2886, the laboratory data were submitted electronically to GeoTracker <br /> ' on September 14, 2004- confirmation numbers 52949444584 and 7624938786. <br /> 2.0 RESULTS OF INVESTIGATIONS <br /> Table 8 of Appendix A is a summary of analytical groundwater data. Groundwater analytical <br /> ' results and field observations are discussed below. <br /> ' • MW-3, MW-6, MW-7, MW-2X, MW-101, MW-102, and all sampled domestic wells <br /> were non-detect above laboratory reporting limits for all analyzed constituents. <br /> • MW-1, MW-4, MW-8, and MW-201 showed low to moderate levels of TPH-G and <br /> ' BTEX constituents. <br /> • MW-2 continues to show high concentrations of TPH-G, and BTEX constituents <br /> during this monitoring event and also in the historical data. <br /> • The monitoring wells: MW-2X (well screen 32.5-35 ft bsg), and MW-102 (well <br /> screen 45.0-47.5 ft bsg) do not show any contamination. This indicates that <br /> contamination did not move to the deeper zones of water aquifer near MW-2 (the <br /> place of highest contamination). <br /> ® MW-5 showed moderate levels of TPH-G, and BTEX constituents. <br /> • Total xylenes (0.5 j,g/L), and MTBE (1.9 µg/L) have been detected in MW-106. <br /> ' Steadily'decreasing contaminant concentrations in MW-106 suggest that the previous <br /> results may be drilling artifacts. However, during installation of this well it was noted <br /> that the soil above the screen interval did contain hydrocarbon contaminants. <br /> t • During the last two events, MW-8 shows contamination from TPH-G and BTEX <br /> constituents. This may indicate the plume has moved in a northeasterly direction and <br /> has impacted MW-8. Concentrations in MW-8 are dramatically lower for the 3rd <br /> quarter monitoring event then they were during the previous quarterly event. <br /> Concentrations in other Zone A wells have increased during this same period (MW-1, <br /> ' MW-2 and MW-4). Further monitoring will be necessary to understand this <br /> phenomenon. <br /> 3.0 FINDINGS AND DISCUSSION <br /> ' The laboratory analytical data generated during the July 23, 2004 groundwater-monitoring <br /> event indicates that MTBE and/or TPH-G and BTEX constituents have been detected in <br /> monitoring wells: MW-1, MW-2, MW-4; MW-5, MW-8, MW-106 and MW-201. <br /> 1 <br />