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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 May 12, 1999 The <br /> groundwater elevation has decreased by an average of 0 56 feet at the five monitor wells <br /> since the previous quarterly monitoring round on March 3, 1999 The general flow <br /> direction is to the west with a southwest trending trough forming through the middle of <br /> the site The overall gradient at the site is 0 001 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 May 12, 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 14000 ug/1 at MW 1 to less than the <br /> laboratory detection limits of 50 ug/1 at the monitor wells MW2, MW3, and MW4 <br /> Monitor well MW5 showed a TPH-G concentration of 60 ug/1 <br /> Benzene concentrations ranged from a maximum of 1900 ug/1 at MW1 to less than the <br /> laboratory detection limits of 0 5 ug/1 at MW2 and MW5 <br /> MTBE concentrations ranged from a maximum of 100 ug/1 at MW 1 to less than <br /> laboratory detection limits of 0 5 ug/l in MW2 <br /> Figure 5 shows the distribution of TPH-G, BTEX, and MTBE in groundwater as <br /> determined from groundwater samples collected on May 12, 1999 Monitor well MW5, <br /> closest to the former UST located at 1856 Country Club Blvd , is showing traces of TPH- <br /> G, BTEX, and MTBE for the first time since it was installed in 1994 <br /> RECOMMENDATIONS <br /> 1) Continue quarterly groundwater monitoring <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 conjuction <br /> with vapor extraction <br /> 3 Sanchez QM 4-6 1999 <br />