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1 <br /> GeoCogica1Tec&ucs 2nc Page 3 <br /> Groundwater Monaonng Report <br /> Project No 723 2 <br /> August 20, 2001 <br /> A chain of custody document, listing all samples collected and their intended analyses, <br /> accompanied the samples from field to the laboratory, thereby providing a means to track <br /> ' their movement and ensure their integrity <br /> 1.3 Laboratory Analyses <br /> ' Theroundwater samples collected on .lune 25, 2001 were delivered to Sherwood Labs of <br /> g p <br /> Hilmar, California (certification#1400) for analysis of <br /> ' • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX) by method EPA method 602 <br /> • Total Petroleum Hydrocarbons as Gasoline (TPH-G) by EPA method 5030/8015(M) <br /> The detection limits for the above analyses are listed in Table 2 of Appendix A, while the <br /> lab analytical results are presented in Appendix B <br /> 1 <br /> 2.0 FINDINGS AND DISCUSSION <br /> The results of the groundwater sample analysis show the following <br /> • The concentrations of BTEX and TPH-G continue to fluctuate in individual monitoring <br /> wells from one sampling event to the next However, the overall trend seems to be <br /> stable <br /> ' • Figure 4 illustrates TPH-G and Benzene concentrations versus elevation in well MW-3, <br /> which hes near the core of the plume There is a direct relationship between a gradually <br /> increasing water table and the TPH-G concentrations However, Benzene <br /> concentrations have stabilized in the well <br /> • Figure 5 illustrates TPH-G and Benzene concentrations versus elevation in well MW-4, <br /> which hes up gradient of the core of the plume The contaminant concentrations have <br /> stabilized in this well in spite of a gradually increasing water table <br /> • Figure 6 illustrates TPH-G and Benzene concentrations versus elevation in deep well <br /> ' MW-101, which lies near the core of the plume The concentrations are approaching <br /> stability The steep decline in the initial concentrations suggests that the contaminants <br /> detected in the well were initially a drilling artifact The low concentrations now <br /> ' detected are probably representative of the lower extent of the groundwater plume <br /> I3.0 CONCLUSIONS & RECOMMENDATIONS <br /> Conclusions <br /> I1 The groundwater contaminant plume is not defined vertically or laterally <br /> • 2 Groundwater flow trends to the northeast to east The southerly flow direction recorded <br /> on December 4, 2000 appears to be anomalous <br /> 1 <br />