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E25 March 2005 �i AGE-NC Project No 98-0540 IPage 3 of 4 ' report(CTEL Project No CT214-0412061),quality assurance/quality control(QA/QC)reports and chain of custody forms are included in Appendix B ' 4.0. SUMMARY AND CONCLUSIONS ' Based upon data collected from the site, AGE concludes the following • During the December 2004 monitoring event,the ground water gradient was 0 002 ft/ft with ' a flow direction toward the southwest, the flow direction was inconsistent with the dominantly southeasterly flow directions from previous monitoring events • TPH-g and the fuel additive 1,2-DCA were the only contaminants of concern detected this quarter, from wells MW-1 and MW-3 Most of the TPH-g reported In sample MW-1 and apparently all of sample MW-3 consisted of 1,2-DCA, at concentrations of 240 µg/l ' 1,2-DCA in 250 µg/1 TPH-g and 350 µg/l 1,2-DCA in 350 µg/l TPH-g, respectively • The detected concentrations of 1,2-DCA have increased significantly the last two quarters The 1,2-DCA concentrations detected In the samples collected from MWA and MW-3 exceeded the State of California's Maximum Contaminant Level (MCL) of 0 5 µg/1 • TPH-g and BTEX concentrations have not been detected in the samples collected from well ' MW-2 for four consecutive quarters • With the exception of the area of well MW-2 north of the former UST location, the vertical Iand lateral extent of impacted ground water has not been fully delineated 5.4. RECOMMENDATIONS Based upon data collected from the site, AGE recommends ' • Continued round water monitorin • g g, ' • Continued work to assess the vertical and lateral impact of 1,2-DCA as per the Cone Penetrometer Testing and Monitoring Well Installation Work Plan, approved by the EHD by letter, dated 12 August 2004 The cone penetrometer testing boring was advanced on 13 October 2004 A deadline of 30 April 2005 has been set to complete the second phase of the work plan, to install two monitoring wells, AGE is completing San Joaquin County permit applications to install the off-site monitoring well • IAdvanced GeoEnvironmental,Inc I