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08/21/97 THU 09:08 FAX 909 335 6120 SECOR REDLANDS Z004 <br /> The laboratory method blanks contained nondetect concentrations of all analytes tested. <br /> Review of laboratory QA/QC data did not identify laboratory methodology errors that would <br /> have affected analyses performed during this investigation. All laboratory QA/QC data are <br /> attached to this report in Appendix C. <br /> July 9, 1997 <br /> Dissolved phase petroleum hydrocarbons, BTEX,MTBE or VOCs were not reported by the <br /> laboratory above method detection limits(MDIs)in the groundwater samples collected from <br /> the four monitoring wells purged and sampled. A summary of the analytical results obtained <br /> is presented in Table 1 and Table 2. <br /> The laboratory method blanks contained nondetect concentrations of all analytes tested. <br /> Review of laboratory QA/QC data did not identify laboratory methodology errors that would <br /> have affected analyses performed during this investigation. All laboratory QA/QC data are <br /> attached to this report in Appendix C. <br /> SUMMARY <br /> Trace levels of petroleum hydrocarbons, characterized as ranging from C10 to C40), were <br /> reported in the groundwater sample collected from monitoring wells MW-1, MW-3 and <br /> MW-4 in May 1997. The two subsequent sampling episodes completed showed nondetect <br /> concentrations of petroleum hydrocarbons in these three wells and monitoring well MW-2. <br /> Given available data, it appears that the hydrocarbons identified in the three wells in May <br /> of 1997, is a result of contamination introduced from drilling auger and not associated with <br /> an on or off site source. <br /> Trace levels of ethlybenzene, 5.7µg/J, were reported in the groundwater sample collected <br /> from monitoring well MW-4 during the June 1997,sampling episode. Given available data, <br /> the reported concentrations would appear to be a "false positive". <br /> Attachments: Table 1 - Historical Groundwater Depths/Elevations and Analytical Testing <br /> Results <br /> Table 2 - Summary of Groundwater Analysis;EPA Test Method 8240,EPA <br /> Test Method 418.1 <br /> Figure 1 - Site Plan with June 24, 1997, Groundwater Elevation Data <br /> Superimposed <br /> Figure 2 - Site Plan with July 9, 1997, Groundwater Elevation Data <br /> Superimposed <br /> Appendix A- SECOR Water Sample Field Data Sheets <br /> Appendix B - Chain-of-Custody Records <br /> Appendix C- Laboratory Data Sheets and QA/QC Summary <br /> JN 40071-13001 <br /> TxwcY.M 3 <br />