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1 1 Mr James L Barton 1 December 2, 2004 Page 9 ' collected during the September 2004 sampling event show that the system was extracting vapors at a rate of 19 02 pounds per day (lbs/day) during that time The system extracted vapors at a rate of 3 35 lbs/day according to data collected in October 2004 ENSR will ' continue to monitor the system on a weekly basis and collect samples for laboratory analysis every month A summary of SVE system operational parameters, destruction efficiencies, and mass flow rates are presented in Table 2 and Table 3 ' Effectiveness of System to Protect Human Health and the Environment Both the AS system and the SVE system are protective of human health and the environment ' Currently, there is no human or ecological exposure to contaminated groundwater or sod at this site The off-gas treatment has proven to be effective in removing at least 96 percent of the CDCs as required by the operating permit Additionally, ENSR has observed a reduction in average concentrations as well as plume distribution since the AS and SVE system operations restarted Additional plume data and mass balance calculations are included in the Comparative Analysis included as the Plume Description section of this report Component Performance �. ENSR has only performed two site visits to collect individual sparge well data July 22, 2004 and August 5, 2004 Data from these collection events are tabulated and presented as Table 4 and Table 5, respectively ENSR intends to develop a monitoring program for the individual sparge and extraction wells to be conducted on a quarterly basis ENSR field personnel will collect pressure and flow rate data from the sparge wells, and vacuum, flow rate, and concentration of volatile organic compounds (VOCs) measured with a photoionization detector (PID) from the extraction wells This information will help determine which wells are operating as intended ENSR intends to implement this schedule during the first quarter of 2005 Upon restarting the SVE system, ENSR discovered a faulty solenoid valve that allows water to travel from the water knockout tank into the holding tank ENSR replaced the faulty solenoid valve with a check valve to prevent water from flowing backward into the water knockout tank The check valve also inhibits ambient air from entering the extraction well stream Bypassing the faulty solenoid valve resulted in minimal system downtime The concentrations of contaminants in the extracted vapor may be low enough (160 pg/L measured on October 29, 2004) that off-gas treatment would be more cost efficient than if the thermal oxidizer were replaced with a catalytic oxidizer or with activated carbon Therm2l oxidation operates by mixing fuel (natural gas) with the extracted vapors effectively burning the contaminants prior to discharging the treated air Catalytic oxidation requires much less fuel by operating at a lower temperature thereby reducing the cost spent on natural gas In the carbon adsorption process, molecules of a contaminated gas are attracted to and accumulate on the surface of the activated carbon kkDcsacramentolproiectstiProtectsl0694015098-2931FinaAReportsl5098 RSE Results Report doc I