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4 <br /> i <br /> 1 <br /> . Mr Ron Rowe <br /> Page 4 of 5 <br /> VAPOR EXTRACTION SYSTEM ACTIVITIES <br /> ' VES Operation <br /> ' The soil vapor extraction system operated on vapor wells VW2, VW5, and VW6 for a total of <br /> 1,474 hours between October 1 and January 3, 2000 <br /> ' The system shut down in October and November for unknown reasons Ground Zero was able to <br /> restart the system on October 4 during regular maintenance and data acquisition Inspections In <br /> November the system remained down from November 8 through November 28, 1999 with <br /> unsuccessful restart attempts The system was restarted successfully on November 29, 1999 and <br /> operated continuously through January 3, 2000 when the system was shut down due to lack of <br /> UST-Fund pre-approval <br /> During the Fourth Quarter 1999, the VES was monitored on a weekly basis The systems <br /> monitoring data sheets are Included in Attachment C On October 18, and December 28, 1999 <br /> ' Influent and effluent vapor samples were collected and submitted to Air Toxics, Ltd for analysis <br /> The samples were analyzed for total purgeable petroleum hydrocarbons (TPPI) and BTEX by <br /> EPA Method TO-3 Samples collected in October and December were also analyzed for MTBE <br /> Vapor Simple Analytical Results <br /> Laboratory reports are Included in Attachment D and are summarized in Table 4 Based on the <br /> TPPH concentrations, the destruction efficiency of the thermal oxidizer during the October and <br /> ' December sampling rounds was 92% or better In cases were the destruction efficiency was less <br /> than 95%, APCD's alternate limit of less than 21bs/day discharge was not exceeded <br /> Vapor concentrations declined during the fourth quarter MTBE was detected at a very low <br /> concentration in the system influent during in October and December <br /> ' System Evaluation <br /> The VES has been removing hydrocarbons from subsurface soil since November 19, 1997 at flow <br /> rates ranging from 270 to 380 cubic feet per minute, including dilution air <br /> As of January 3, 2000 the system had been in operation for 12,225 hours Based on graphical <br /> ' interpolation between measured influent vapor concentrations, as of December 31 an estimated <br /> 12,670 pounds of hydrocarbon contamination had been removed from the soil Table 5 <br /> summarizes flow and vapor concentration averages as well as the total hydrocarbon mass <br /> removed from the soil The most recent hydrocarbon removal rate was approximately 2 pounds <br /> per day <br /> roeklgmrAgm 1999 <br /> 1 <br />