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' 12 July 2006 • AGE-NC Project No 95-0130 ' Page 13 of 14 • Between 06 December 2005 and 14 March 2006, an estimated 75 pounds of petroleum ' hydrocarbons were extracted from ground water (Table 9) • A decreasing trend of dissolved TPH/BTEX was evident for P&T influent concentrations ' during the I" Quarter 2006, however, a significant MTBE increase was detected from the March 2006 sample A plot of the influent TPH-g concentrations versus time is included in Appendix L ' • Since initiation of the P&T system in November 2004, the total volume of petroleum hydrocarbon-impacted water extracted is estimated to be approximately 1,007,300 gallons ' (Table 7), the mass of petroleum hydrocarbons removed from the above total volume of 1,007,300 gallons is estimated at approximately 282 pounds of extracted petroleum hydrocarbons 6.0. RECOMMENDATIONS Based upon the results of the first quarter 2006 investigation, AGE recommends • • Continued quarterly ground water monitoring of wells V W-l C,VW-2A,VW-3A,MW-6(A- E), MW-7(A-E)and MW-8 The Second Quarter 2006 ground water monitoring event was coordinated with Stratus Environmental (Arco Gas Station, 130 South Wilson Way) on 30 May 2006 ' • Conduct future ground water monitoring events concurrently with the Knowles/Roek Property site(102 South Wilson Way) and the Arco AM/PM site (130 South Wilson Way), • Continued quarterly depth-to-water measurements in all monitoring wells at the site, but I reduced ground water sampling frequency from a quarterly to a semi-annual program, AGE believes that continued quarterly ground water sampling from wells MW-1 through MW-5 at this stage of the investigation is not cost effective and will not provide enough useful information to supplement the ongoing investigation Semi-annual sampling events should be adequate to monitor ground water impact at these wells and should be re-evaluated on a semi-annual basis • A work plan(Additional Site Assessment Work Plan, dated 15 November 2005, for four(4) off-site CPT soil borings was previously submitted to the SJCEHD,the borings were located I east and southeast of the site in the northbound lane of Wilson Way AGE has tentatively scheduled the work to commence on 21 August 2006 Advanced GeoEn"ronmental,Inc