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, 1 , I n i i 26 April 2004 AGE-NC Project No 97-0333 I Page 10 of 12, i N , No other constituents of concern were detected above laboratory reporting limits in the water r ' samples collected during the fourth quarter 2003 sampling event Analytical results of ground water i monitoring well samples are summarized in Tables 3 and 4 The laboratory reports (Cal Tech 1 Environmental Laboratories Identification No 0311-125)and chain-of-custody forms are presented in Appendix G 5.0. SUMMARY AND CONCLUSIONS 4 Previous soil characteristics data obtained by a CPT investigation enabled AGE,to define four Informal hydrologic units(CPT Sate Investigation-Fourth Quarter 2000, dated 07 February 200 1) The Informal hydrogeologic units were defined as First Zone(15-47 feet bsg), Second Zone(58-92 feet bsg, Third Zone (102-120 feet bsg) and Primary Aquifer Zone (128-150 feet bsg) I � The results of pump and treat ground water remediation between 10 September 2003` and 26 December 2003 are as follows • Groundwater pump-and-treat operations were temporarily suspended between 18 September 2003 and 20 October 2003 due to detection of TBA at the pump-and treat effluent Ground water pump-and-treat operations were restarted on 20 October 2003 following a change-out of carbon media from the 3"d and 4th in-line media vessels „ Approximately 205,130igallons of hydrocarbon-impacted ground waterwere extracted from � f well EW-1,which was completed in the First Zone aquifer A total volume of approximately 1,871,628 gallons of hydrocarbon-impacted ground water has been treated at the site since ' { the start-up period in January 2002 (Table 5) • Dissolved MTBE was detected from grab samples collected at the influent end of the treatment system,at concentrations between 2,700Fgg/1 and 3,800 pg/l, laboratory analysis of grab water samples collected at the effluent-end of the pump and treat system detected TBA during the September monthly monitoring event(Table 1) r • ' Between 10 September'2003 and 26 December 2003, an estimated 5 18 pounds of MTBE was extracted from ground water (Table 5, Appendix B), a total mass of 220 34 pounds of iMTBE has been'removed since Initiation of thepump and treat system on 21 January 2002 A plot of cumulative ground water pump and treat mass removal versus time and a plot of, influent ground water MTBE�concentrations,versus time are included in Appendix C, i although a slight increase was reported in December 2003, the overall general trend of } { decreasing MTBE concentrations is evident 'I lieh I I I I i Advanced GeoEnvironmental,Inc l