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03 February 2004 <br /> AGE-NC Project No 98-0500104-1127 <br /> Page 5 of 6 <br /> 4.0. CONCLUSIONS <br /> The findings from the December 2003 ground water monitoring event are as follows <br /> I • The ground water elevation at the site has increased an average of 3 feet between the July and <br /> December 2003 <br /> • The ground water flow direction in the was toward the northeast 0 001 feet/feet and 0 003 <br /> feet/feet The flow directions and gradients are similar to previously monitoring events <br /> • The maximum detections of TPH were in ground water samples from northern edge of the <br /> suspected Stoddard release area and southwest of the former UST and directly west of the <br /> former UST dispenser area <br /> • The maximum concentrations of BTEX compounds were detected in the sample from well <br /> MW-1 Additionally,BTEX compounds were detected in the sample from well MW-16(near <br /> the former dry well locations) <br /> I • TBA was detected in samples at moderate to low concentrations, near the former UST <br /> release, likely indicating the prior presence of MTBE At a minimum this fuel additive was <br /> Irelease at the site <br /> • 1,2-DCA was detected in samples from wells across the site, constructed at varying depth <br /> Generally, concentrations ranging from 2,600 µg/1 at the former UST dispenser to 0 8 µg/1, <br /> in the furthest well to the northwest of the site The lateral and vertical migration of the <br /> 1,2-DCA has been defined from the former UST area to the west,through Intermediate- and <br /> deep-screened ground water Intervals and north to a depth of 135 feet bsg <br /> • The lateral, vertical and migration routes of the TPH and BTEX compounds have been <br /> established The lateral,vertical and migration routes of the dissolved 1,2-DCA plume have <br /> been assessed and is only defined to the southeast of the site The northern definition of the <br /> dissolved 1,2-DCA plume needs to be completed, although current concentrations through <br /> out the plume appear stable over the monitoring period <br /> I <br /> I5.0. RECOMMENDATIONS <br /> Based on the findings of this Investigation, AGE recommends <br /> • Continue quarterly groundwater monitoring The next monitoring event is scheduled for early <br /> March 2004 <br /> • AGE submitted Interim Soil Vapor Extraction and Site Assessment Work Plan, dated 14 <br /> November 2003 as required by the RWQCB by letter dated 15 September 2003 <br />' Advanced GeoEnvironmental,Inc <br /> I <br />