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1 <br /> 4.0 CONCLUSIONS AND RECOMMENDATIONS <br /> Groundwater levels have risen an average of 1 77 feet since groundwater levels were last <br /> measured on February 18, 1999 The groundwater gradient was calculated at 0 001 foot/foot in a <br /> northeasterly direction This result is consistent with historical groundwater flow and gradient data <br /> i <br /> Concentrations of dissolved gasoline hydrocarbons in the groundwater samples collected this <br /> quarter from MW-6, MW-7, VW-1 and VW-2 remain relatively consistent with previous sampling <br /> results In VW-2, the concentration of TPH-as-gasoline decreased from 3,200 ppb on February 18, <br /> 1999 to 1,200 ppb this quarter The concentration of benzene also decreased, but the <br /> concentration of MTBE increased slightly from 870 ppb during the last sampling event to 950 ppb <br /> this sampling event TPH-as-gasoline, BTEX and MTBE were not detected in MW-6 and MW-7 <br /> On June 2, 1999, ENSR started the SVE system Between June 2 and 18, 1999, the system <br /> operated for a total of 380 hours with an up-time of 100% The system operated at an average flow <br /> rate of 226 scfm and a vacuum range of 65 to 73 inches of water column At startup, the system <br /> was recovering approximately 123 5 pounds of hydrocarbons per day <br /> Ramage Environmental recommends the following course of environmental corrective action <br /> r� <br /> 1 Continue to monitor and sample groundwater from the four water table wells on a quarterly <br /> basis The next quarterly groundwater monitoring is scheduled for August 1999 <br /> 2 ENSR to continue operating and monitoring the soil vapor extraction system <br /> r <br /> r <br /> r <br /> r <br /> r <br /> • 7 <br /> r <br />