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' 08 September 2009 AGE -NC Project No. 03-1055 Page 7 of 19 TPH-g, BTEX, MTBE, and 1,2 -DCA are present at concentrations above the Department of Health Services' Maximum Contaminant Levels forthese contaminants in ground water. The vertical and lateral extent of ground water contamination is not yet defined in any direction and based upon the findings of this investigation, AGE recommended preparation of a work plan to delineate the lateral and vertical extent of petroleum hydrocarbon -impacted soil and ground water. Historical soil and grab ground water analytical results from the former Chevron site are summarized in Tables 5 and 6, respectively. 2.4. GROUND WATER MONITORING PROGRAM Between December 2000 and July 2009, AGE performed 24 ground water monitoring events at the site to monitor dissolved petroleum hydrocarbon concentrations in ground water and to characterize ground water flow direction and gradient. On 21 July 2009, a quarterly ground water monitoring event was conducted utilizing ten wells MW -5 through MW -14; wells MW -6, MW -8, MW -12, MW -13, and MW -14 were sampled in accordance to the EHD letter dated 13 May 2009 (Appendix A). Monitoring was performed in accordance with AGE's standard monitoring and sampling procedures, provided in Appendix D. No exceptions to AGE's standard procedures were noted. Field data and logs are provided in Appendix E. 2.4.1. Ground Water Depths Generally, ground water levels between 2000 and 2009 were recorded at the site to be between 6.77 feet and 13.83 feet below the top of the well casings (btoc), and averaged 10.74 feet btoc. During the July 2009 monitoring event, depth to ground water ranged between 10.66 feet (MW -6) and 11.63 feet (MW -14) btoc. Ground water elevations at the site generally fluctuated between 35.29 feet above the North America vertical datum (NAV D88) and 41.49 feet above NAVD, and averaged 3890 feet above NAVD. During the July 2009 monitoring event, ground water elevations ranged between 38.31 feet (MW -5) and 38.68 feet (MW -10) above NAVD. Ground water monitoring data is summarized on Table 3. Graphs illustrating trends in ground water monitoring data are included in Appendix F. Depth to water data collected during the July 2009 monitoring event were uploaded to the State GeoTracker database under confirmation number 8607827305. Advanced GeoEnvlronmentnl, Ine.