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I16 August 2004 <br /> AGE-NC Project No 98-0433 <br />' Page 4 of 5 <br />' 4.0. SUMMARY AND CONCLUSIONS <br /> Based upon the data collected during the Third Quarter 2004 monitoring event, AGE concludes <br />' A -.-o �1 11� q yy� 115)v <br /> • Ground water at the site was encountered at approximately 2 �feet below the casing <br /> tops The prevailing ground waterr4low direction was generally toward the east-southeast at <br />' gradients ranging between 0 0009 ft/ft west of the former UST location and 0 004 ft/ft to <br /> 0 009 ft/ft east of the former UST location <br />' The highest concentration of TPH-g was in the area of monitoring wells MW-1 and MW-9, <br /> located adjacent to the former UST area Compared to the previous quarter, the TPH-g <br /> concentration in ground water decreased in samples MW-1 and MW-6, and increased in <br />' samples MW-8 and MW-9, TPH-g was not detected in sample MW-6, compared to a <br /> concentration of 7,300 µg/1 the previous quarter <br /> • TPH-diesel concentrations decreased in wellrmW 1 and+PAL-6,kPH-d was not detected in <br /> Iwell MW-6, compared to a concentration of 34,000 µg/1 the previous quarter (Table 1) <br /> • Benzene detected In samples MW-1 (4 1 µg/1) and MW-6 (18 µg/1) were above the DHS' <br />' Maximum Contaminant Level(MCL) MTBE detected in samples MW-1,MW-8 and MW-9 <br /> at concentrations as great as 2,300 µg/1 was significantly above the DHS' primary MCL 1 <br /> I • The lateral extent of dissolved MTBE is generally defined by the current well network, <br /> Including the wells sampled at the Ripon Farm Service site directly south of the subject site <br /> The vertical extent of MTBE at the former UST area is not defined below a depth of 40 feet <br /> I bsg <br /> • The lateral extent of TPH-g and BTEX is defined in the former UST area, however, it is <br /> undefined in the area of MW-6 <br />' S.O. RECOMMENDATIONS <br /> Based on the results of this investigation, AGE recommends <br />' • Continued quarterly monitoring at the site, the next monitoring event should be scheduled <br /> for Fourth Quarter 2004 <br /> I • Coordinate the ground water monitoring activities of Jimco Truck Plaza and the add acent <br /> Ripon Farm Service (22871 South Highway 99) to occur concurrently <br /> I 4 <br /> Advanced GeoEnvirenmental,Inc <br />