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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 December 2, 1999 The <br /> groundwater elevation has decreased by an average of 0 45 feet at the five monitor wells <br /> since the previous quarterly monitoring round on September 8, 1999 The general flow <br /> direction remains to the west The groundwater elevation gradient at the site for <br /> December 2, 1999 averaged 0 001 feet/linear foot over the site <br /> RESULTS OF CERTIFIED ANALYSIS OF GROUNDWATER SAMPLES <br /> The results of the certified analyses of groundwater samples collected from the five <br /> monitor xkells on December 2, 1999 are shoe n in Table 1 Copies of the laboratory <br /> reports are included as Appendix C of this report <br /> TPH-G concentrations ranged from a maximum of 20000 ug/1 at MW1 to less than the <br /> laboratory detection limits of 50 ug/l at monitor wells MW3, MW4, and MW5 <br /> Benzene concentrations ranged from a maximum of 2800 ug/l at MW1 to 0 5 ug/1 at <br /> MW4 <br /> • MTBE concentrations ranged from a maximum of 150 ug/1 at MWl to less than <br /> laboratory detection limits of 0 5 ug/1 in MW2 <br /> Figure 5 shows the distribution of TPH-G, BTEX, and MTBE in groundwater as <br /> determined from groundwater samples collected on December 2, 1999 The small <br /> decrease in groundwater elevation at the site since the previous quarterly monitoring <br /> iound was not accompanied by any significant changes to the concentrations of TPH-G, <br /> BTEX, or MTBE observed in any of the wells <br /> RECOMMENDATIONS <br /> 1) Continue quarterly groundwater imonitonng <br /> 2) Conduct records review of LUFT site located. at 1856 Country Club Blvd <br /> 3) Install offsite monitor well west of MW1 to define downgradient extent of <br /> groundwater contamination plume <br /> 4) Conduct pump test at existing on-site monitor well to determine feasibility of <br /> dewatering during overexcavation of former UST area and/or dewatering in conjunction <br /> with vapor extraction <br /> 3 Sanchez QM 10-12 1999 <br />