ARCHIVED REPORTS_XR0012005 - Laserfiche WebLink

Home Browse Search

• Mr. Ron Rowe Page 4 {Vapor Sample Analytical Results Laboratory reports are included in Attachment D and are summarized in Table 4 Based on the TPPH concentrations, the destruction efficiency of the thermal oxidizer during all sampling rounds was 99% or better Due to relatively high effluent concentrations reported from the March 16 sampling, a possible source of cross contamination either in the sampling pump or the copper effluent sampling tube was suggested. Therefore, a vacuum box has since been used to collect effluent samples Overall, analytical results of second quarter influent samples indicated vapor concentrations similar to those from first quarter 1998 Influent vapor concentrations measured in May were higher than in April, most likely because of the interruption in extraction System Evaluation The VES has been removing hydrocarbons from vapor wells VW2, VWS, and VW6 since November 19, 1997 and from VW3 since January 5, 1998 at combined flow rates ranging from 270 to 370 cubic feet per minute (cfm) As of June 28, the system had been in operation for 3,552 hours Based on graphical . interpolation between measured influent vapor concentrations, as of June 15 an estimated 7,900 pounds of hydrocarbon contamination had been removed from the soil Table 5 summarizes flow and vapor concentration averages as well. as the total hydrocarbon mass removed from the soil RECOMMENDATIONS Ground Zero recommends continuing quarterly sampling to monitor the extent of gasoline hydrocarbons in groundwater Analysis for oxygenates will continue for wells MWl, MW3, MW4, MW 11, MW 12, and MW 13 for next c uarter. The next sampling event is scheduled for August 1998 Your office will be provided 48-hours notice of any field work Ground Zero also recommends continuing weekly monitoring of the VES and collecting monthly vapor samples for laboratory analysis Effluent sampling procedures will continue using the vacuum box "'%a=UqmI sva I ' i I