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R603 UPDATE-18 7/09/93 <br /> delivered on ice to a state certified testing laboratory <br /> (SUPERIOR PRECISION ANALYTICAL, INC DHS#1332) for chemical <br /> analyses These samples were analyzed for TPH and BTEX <br /> concentrations using EPA Methods 8015 and 602 respectively. <br /> Since diesel has never shown up in the sample results, the <br /> samples obtained on 11./27/90 and later were analyzed using EPA <br /> methods 5030 and 602 for Total Fuel Hydrocarbons and BTEX. The <br /> next quarterly sampling will occur in September, 1993 . <br /> 3 . 0 RESULTS <br /> GROUND WATER SAMPLE RESULTS <br /> Ground water samples were obtained from all of the monitoring <br /> wells on June 14 , 1993 <br /> The latest sample results showed a decline in contaminant levels <br /> associated with the ground water at MW1 and MW3 Of the other <br /> wells that have some degree of ground water contamination (MW2, <br /> MWB , MW10 and MW12) showed slight increases, see Table 1 and <br /> Figures 5A and 5B <br /> The increase in contaminant concentrations found at MW2 and MW10 <br /> is thought to be associated with the vacuum extraction at these <br /> wells, concentrating the contaminant from adjacent areas to the <br /> source of the vacuum, see Table 1 The increase in contaminant <br /> concentrations found at MW8 and MW12 is associated with the rise <br /> in the ground water to near the 50 foot depth This depth is <br /> where the highest levels of gasoline range hydrocarbons have been <br /> detected in soil samples from the exploration and well borings, <br /> see Fence Diagram - Figure 6 . <br /> VAPOR RECOVERY OPERATIONS AND RESULTS <br /> Presently (June 28, 1993 ) the REMOX units have operated for a <br /> total of 9779 hours out of a total of 14184 5 hours (68 90) . The <br /> new replacement unit has operated 5777 hours out of 7537 . 5 hours <br /> (76 60) , removing and destroying and estimated 69298 pounds of <br /> gasoline range hydrocarbons (June 22 , 1993) and an estimated <br /> 59261 pounds of oxidized gasoline range hydrocarbons as CO2 <br /> (Average 200 cfm flow rate X average CO2% (1 25) x 9636 hours <br /> operated x 60 min/hour x pound CO2 conversion 0 00041 lb/cf/°s) <br /> for a total of 128559 pounds of gasoline range hydrocarbons <br /> removed from the subsurface, see Tables 2 , and 3 and Appendix E- <br /> Air Monitoring Report <br /> Since February 18 , 1993 the vapor recovery/destruction has been <br /> declining from an average above 200 pounds per day of gasoline <br /> range hydrocarbons to below 50 pounds per day of gasoline range <br /> hydrocarbons, see Table 2 and concentration charts Figures 7A and <br /> 7B These charts indicate that the lighter compounds of gasoline <br /> range hydrocarbons (benzene, toluene, etc ) have been greatly <br />. reduced with a moderate reduction of the heavier compounds <br /> (ethylbenzene, xylenes, etc ) <br /> a PAGE 2 <br />