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15 May 2002 <br /> AGE-NC Project No 98-0432 <br /> Page 3 of 4 <br /> ' to 22 26 feet above mean sea level in monitoring wells MW-6 and MW-5, respectively <br /> (Table 1) Ground water elevation In the monitoring wells increased an average of 2 4 feet since the <br /> previous monitoring event in October 2001 A ground water elevation contour map for April 2002 <br /> is Illustrated on Figure 3 Based on grow d water elevation data,groundwater flow direction Is away <br /> fir well -1 and MW-3 to the f�west The typical ground water flow direction at the site Is <br /> no�i to no west The ground water elevation value from well MW-5, up-gradient, was not used <br /> for the ground water elevation contour map, the value was out of range of all other values by one <br /> ' foot <br /> 32 GROUND WATER ANALYTICAL RESULTS u b3 <br /> ' TPH-d was detected In the ground water samples collected from well <br /> MW4—an4 MW-2 at <br /> concentrations of 110 microgram per liter(�tg/l) The highest concentration of MTBE detected was <br /> In sample MW-1 at 4,000 gg/1 MTBE was also detected In the samples from well MW-2 at 88rg/1 <br /> ' by EPA Method 8260 Modified 3 f tDl a 3 <br /> . There were no reported detections of fuel oxygenating compounds in any of the other ground water <br /> ' samples analyzed In addition, there were no reported detections of BTEX, TPH-g or other fuel <br /> additives In any of the ground water samples analyzed <br /> Analytical results from ground water samples are summarized in Tables 2 and 3 The laboratory <br /> reports(MAI Laboratory ID 0204237-001 A to 006A),quality assurance and quality control(QA/QC) <br /> ' reports and cham-of-custody forms are included In Appendix B <br /> ' 4.0. SUMMARY AND CONCLUSIONS <br /> The following conclusions were drawn from the results of this Investigation <br /> �ou� v 311q 03 <br /> • During this quarter, the prevailing ground water flow direction Is towards the n�thwest <br /> overall This inconsistent flow dlrcctlon may be due to a surface water release near northern <br /> ' portion of the site and will be verified by further sampling events or may be due to small <br /> measurement variations with ground water at a very low gradient <br /> • TPH-d, detected only In MW-1 at a concentration of 110 gg/l <br /> • MTBE was detected in wells MW-1 and MW-2 at concentrations as high as 4,000 pg/1 Two <br /> water samples collected had reported concentrations of MTBE that exceed the State of <br />' California maximum contaminant level (MCL) m w-1 I -4/DDb.u_ 1 L <br /> Advanced GeoEnvironmental,Inc <br />