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14 December 2011 AGE-NC Project No. 99-0682 Page 4 of 5 The laboratory report(Cal Tech Environmental Laboratories Project No. CT214-1110190), quality assurance/quality control reports, and chain-of-custody forms are included in Appendix E. Electronic deliverable format (EDF) files and depth-to-water data were uploaded to the State GeoTracker database; confirmation numbers are 2138478100 and 7707002043. 5.0. CONCLUSIONS Based upon the results of the ground water monitoring, AGE presents the following conclusions: • The average ground water elevation across the monitoring well network during the January 2011 monitoring event was 26.93 feet below NAVD88, indicating an average increase in ground water elevation of 1 .58 feet from the January 2011 monitoring event. A graph depicting trends in ground water measurements is included in Appendix D. • The highest concentration of dissolved hydrocarbons continues to occur in the area of the former USTs. TPH-g, TPH-d, BTEX compounds and 1 ,2-DCA were reported at significant concentrations in the water sample collected from monitoring wells MW-1A(screened from 20-40 feet bsg) and MW-8 (screened from 59-69 feet bsg). Additionally, significant concentrations of dissolved hydrocarbons were reported at well MW-11, northeast of the former UST area, indicating a historical ground water flow direction. • Historically, contaminants have generally increased in well MW-8, located in the source area, and contaminants have decreased in well MW-7 since the initial monitoring of the wells in April 2007. During the October 2011 monitoring event, concentrations of contaminants in well MW-8 increased and decreased in wells MW-1A, MW-6 and MW-7; overall, natural attenuation does not appear to be producing a declining trend. Graphs depicting trends in contaminant concentrations in wells MW-1A, MW-6, MW-7 and MW-8 are included in Appendix D. • Currently,the lateral extent of petroleum hydrocarbon-impacted ground water in the upper water bearing units (HU 1) appears to be defined to the southeast (MW-4) of the former UST area, north (MW-3 and MW-5), east of well MW-6 and south of the site by soil boring samples (Appendix A). • The lateral extent of hydrocarbon-impacted ground water within the 60 to 75 feet bsg water bearing zone (HU2-3) is defined to the west-northwest by well MW-9, to the south by boring CPT-5, to the east or southeast with samples from boring B-5, and to the northwest by boring CPT-6. The lateral extent of hydrocarbon-impacted ground water is undefined to the north and northeast of the site, as illustrated on Advanced GeoEnvironinental,Inc.