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20 March 2000 <br /> AGE-NC Project No 96-0232 <br /> Page 4 of 5 <br /> Analytical results of the ground water samples are summarized in Table 2 The laboratory reports <br /> (Castle Analytical Laboratory Reference No 2855 and McCampbell Analytical Inc I D No 31869 <br /> through 31879) and chain-of-custody forms are presented in Appendix B <br /> 4 0. SUMMARY AND CONCLUSIONS <br /> The implications from the findings of the February 2000 investigation are <br /> • Ground water monitoring data collected at the Flag City Chevron site indicated a ground <br /> water flow direction generally toward the east-northeast at an average gradient of 0 001 ft/ft, <br /> ground water monitoring data collected at the Three B's Truck Plaza site indicated a ground <br /> water flow direction generally ranging from the east-northeast to the east-southeast at an <br /> average gradient of 0 003 ft/ft Due to the low gradient at the site, slight variations in ground <br /> water measurements or changes of recharge/discharge of the local ground water could greatly <br /> modify ground water flow direction <br /> • The highest MTBE concentration was encountered in the ground water sample collected <br /> from morutoring well MW-1 (screened 9 to 24 feet bsg), MTBE-impact in the area of MW-1 <br /> may also be present at greater depth <br /> • MTBE concentrations have steadily increased in ground water samples collected from MW-1 <br /> between July 1996 and February 2000 <br /> • Dissolved TPH-g and benzene were detected at MW-2 for the first time in nine ground water <br /> sampling events, furthennore, MTBE concentrations increased approximately one order of <br /> magnitude at MW-2 suggesting migration of the TPH-g, BTEX and MTBE plume towards <br /> the east-southeast <br /> • MTBE was detected in the ground water sample collected from MW-6B, screened between <br /> 43 and 48 feet bsg, monitoring well MW-6B is representative of deeper ground water <br /> conditions MTBE-impact in the area of MW-6 may also be present at greater depth <br /> • The dissolved MTBE plume appears to be at least 41 feet thick in the area of MW-6, with <br /> depth, the dissolved MTBE concentrations appear to be constant <br /> • The horizontal and vertical extent of MTBE-impacted ground water has not been delineated <br /> toward the west, southwest, east and southeast <br /> • MTBE has impacted the domestic water well located 150 feet west-southwest of the subject <br /> site <br /> Adianced GcoEmironmental,Inc <br />