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O1 February 2005 AGE-NC Project No. 98-0521 Page 5 of 6 The results of the May 2004 monitoring event are as follows: • TPH-g was only detected in the sample collected from monitoring well MW-4 at a concentration of 620 pg/l. • BTEX constituents were detected in the samples collected from monitoring wells MW-2 and MW-4 at maximum concentrations of 47 pg/1 benzene, 3.3 pg/1 toluene, 24 pg/l ethylbenzene and 61 µg/1 total xylenes from MW-4. • MTBE was detected in wells MW-1, MW-2 and MW-4 by EPA Method 8260B at concentrations of 2.3 µg/1, 210 µg/1 and 120 gg/l, respectively. • TBA was detected in the sample collected from MW-4 at a concentration of 31 µg/l. No other analytes were detected in the samples collected during the May 2004 monitoring event. Analytical results from the monitoring well ground water samples are summarized in Tables 4 and 5. The laboratory report (MAI Work Order 0405430), quality assurance/quality control (QA/QC) reports and chain of custody forms are included in Appendix D. Documents confirming the upload of laboratory electronic deliverable format (EDF) files and depth to water measurements to GeoTracker are included in Appendix E.The lateral extent of dissolved contaminants is depicted on Figure 4. 4.0. SUMMARY AND CONCLUSIONS The following conclusions were drawn from the results of the May 2004 investigation: • The ground water remediation system was started and sampled on 22 May 2004. • Dissolved hydrocarbons were detected in the influent ground water sample collected at 200 µg/l TPH-g, 1,700 µg/1 TRPH, 160 pg/1 MTBE and 7.4 µg/1 benzene. • Ground water at the site was encountered at approximately 7.3 feet bsg. The prevailing ground water flow direction at the site was generally toward the northeast. The ground water hydraulic gradient was approximately 0.013 ft/ft. • TPH-g,BTEX constituents and TBA were detected in the sample from MW-4. Benzene was detected in the sample from MW-2. The fuel oxygenate MTBE was detected in samples collected from wells MW-1, MW-2 and MW-4. • The concentrations of benzene detected in the samples from MW-2 and MW-4 were above the DHS' Primary Maximum Contaminant Level (MCL) of 1.0 µg/1 in drinking water. The concentrations of MTBE detected in samples MW-2 and MW-4 were above the DHS' Advanced Geo Environmental,Inc.