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1 <br /> Fnri oll Mn1711n Filo situ <br /> 11(ll'tody 0.1,01111dwfj1fi1'�?I; 1111[l1'ii1 fi 1(ll'I <br /> LProject No. 207.2 <br /> _ April 18, 2005 <br /> 3.0 DISCUSSION <br /> E <br /> 3.1 Discussion of Data . <br /> .Field and analytical data results are'summarized in Summary Table 1. and <br /> illustrated in Figures 3 through 5. fr <br /> i <br /> The map of groundwater gradient (Figure 3) suggests.that the flow direction <br /> and gradient of groundwater is consistent with historical measurements. The <br /> water table has risen about 3 feet since the last monitoring event in December. <br /> I Based on a review of overall trends-incontaminantconcentrations, the total <br /> I <br /> concentrations of dissolved phase.gasoline have fallen substantially since the <br /> remedial system was started in the fall of 2003. ,The following list describes <br /> the observed effect on each of the affected monitoring wells. <br /> MW-1 About 10 percent TPH reduction to about 90,000 ppb—40% since 1992 <br /> MW-2 About 50 percent TPH reduction to 15,000 p b—75% since 1992 h <br /> -� MW-3 About 20 percent TPH reduction to 1.5,000 ppb—50% since 1992 <br /> MW-5 No short—term reduction but 98 pucent reduction since 1992 <br /> L MW-6 About 30 to 40 percent short-term reduction—99% since 1992 <br /> Wells MW-4, MW-7, MW-8, MW-10 produce clean groundwater samples <br /> We estimate that approximately 7,000 pounds of gasoline have been removed <br /> from the subsurface using the vapor extraction system. <br /> L3.2 Future Work Schedule- <br /> LZ <br /> Quarterly groundwater monitoring will continue. The vapor extraction I air <br /> sparge remedialsystem will continue in operation. <br /> l L i <br /> i <br /> P <br /> 2937 Veneman Ave.,#$240 Geo-Phase Environmental Inc. Phone (209)569-0293 <br /> Modesto, CA 95356 Fax (209) 569-0293 <br />