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►1 1 <br /> 08 January 2004 <br /> SAGE-NCPiojectNo 95-0103 <br /> Page 7 of 8 <br /> • The average ground water level was approximately 15 75 feet below the top of the casing, <br /> a ground water decrease of approximately 1 3 feet since the monitoring event in April 2003 <br /> The map of ground water contours indicates a general ground water flow toward the southern <br /> portion of the site The ground water table in monitoring wells was generally within the <br /> sciecned interval, these wells should yield samples representative of shallow ground water <br /> conditions <br /> • The concentrations of TPH-g continue to decline in wells MW-1 and MW-3, however and <br /> increase of TPH-g was observed well MW-4 = <br /> • TPH-g and BTEX concentrations have decreased in the monitoring well samples over the <br /> remediation period The overall reduction of benzene on- and off-site indicates successful <br /> removal of dissolved hydrocarbons and capture of the off-site dissolved hydrocarbons,based <br /> on monitoring trend analysis (Appendix F) <br /> • The benzene concentration in well MW-4 continues to show a decline,however,the detected <br /> concentration of 8 4 ugll is above the DHS Maximum Contaminant Level(MCL)of 10µg/l <br /> in drinking water <br /> • MTBE concentrations present in ground water decreased,the maximum MTBE concentration <br /> was 9 G pg/1, detected in well MW-1, and does not exceed the MCL of 13 µg11 for drinking <br /> water The MTBE distribution pattern suggests that ground water extraction is successfully <br /> beginning to draw the off-site MTBE back towards the site <br /> 5.0. RECOMMENDATIONS r <br /> Based upon the results of the fourth quarter 2003 groundwater monitoring event,AGE recommends <br /> • Continued quarterly ground water monitoring at the site as required by California Code of <br /> Regulations, the next monitoring event should be scheduled for December 2003 <br /> • Continued operation and maintenance of the ground water extraction and treatment system <br /> during the fourth quarter of 2003, AGE will evaluate the performance of the ground water <br /> extraction system at the end of 2003 <br /> Ali Y r <br /> Advanced Geotnviron mental,Inc <br />