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RESULTS OF QUARTERLY GROUNDWATER MONITORING <br /> GROUNDWATER GRADIENT AND FLOW DIRECTION <br /> Figure 4 shows the groundwater elevation gradient and flow direction determined from <br /> depth to water measurements at the five on-site monitor wells on March 3, 1999 The <br /> groundwater elevation has increased by an average of 2 64 feet at the five monitor wells <br /> since the previous quarterly monitoring round on December 7, 1998 The general flow <br /> direction is still to the west, although the average rise in water elevation of 2 64 feet was <br /> not uniform over the site, resulting in an unstable lobe in the contour gradients at the <br /> northern end of the property The overall gradient at the site ranges from 0 002 to 0 005 <br /> feet/linear foot <br /> RESULTS OF CERTIFIED ANALYSIS OF GROUNDWATER SAMPLES <br /> The results of the certified analyses of groundwater samples collected from the five <br /> monitor wells on March 3, 1999 are shown in Table 1 Copies of the laboratory reports <br /> are included as Appendix C of this report <br /> TPH-G concentrations ranged from a maximum of 7600 ug/I at MW 1 to less than the <br /> laboratory detection limits of 50 ug/l at the remaining four monitor wells <br /> Benzene concentrations ranged from a maximum of 2100 ug/1 at MWl to less than the <br /> laboratory detection limits of 0 5 ug/l at MW3, MW4, and MWS <br /> MTBE concentrations ranged from a maximum of 160 ug/1 at MW1 to less than <br /> laboratory detection limits of 0 5 ug/l in MW3 <br /> Figure 5 shows the distribution of TPH-G, BTEX, and MTBE in groundwater as <br /> determined from groundwater samples collected on March 3, 1999 The increase in <br /> groundwater elevations since the previous quarterly monitoring round in December 1998 <br /> has been accompanied by a decrease in TPH-G concentrations at MW 1 MTBE <br /> concentrations were observed in four of the five wells including MW5, farthest from the <br /> source area at the site <br /> RECOMMENDATIONS <br /> 1) Continue quarterly groundwater monitoring <br /> I <br /> 2) Conduct records review of LUFT site located at 1856 Country Club Blvd <br /> 3) Construct new workplan for the site that includes overexcavation of the tank pit area <br /> as originally proposed by William Hunter and Associates and the installation of two <br /> additional monitor wells to measure TPH-G, BTEX, and MTBE concentrations at depths <br /> below the current monitor well slotted intervals <br /> 3 Sanchez QM 1-3 1999 <br />