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Technology Laboratory (ATL) in Signal Hill, California Groundwater samples collected on July 2, 2003 specifically for metals analysis were transported to Chroma Laboratory in Pleasanton, California to avoid exceeding hold times due to ATL's July 4"' holiday schedule The water samples were analyzed for BTEX, 1,2-DCA, EDB, and FOCs following EPA method 9260B and for TPHg following EPA 8015 Modified Per the RWQCB written request, the water ' samples collected from wells MW-5, MW-5D, MW-6, and MW-9 were analyzed for dissolved metals following EPA Method 200 8 and for mercury following EPA Method 245 1 ' 33 Remediation System Operation and Maintenance and Performance Summary Operation and maintenance (O&M) of the remediation system is performed monthly (or as needed) Changing the catalytic oxidizer recorded temperature chart paper is performed weekly A brief description and performance evaluation of the remedial system between March 10 and July 16, 2003 1 is presented below 3 3 1 SVE System The SVE system is comprised of ten SVE wells (V-1 through V-10) until June 24, 2003 the SVE ' system used a Solleco TCAT 500 scfin catalytic oxidizer as the abatement device During the reporting period of March 10 through July 16, 2003, the SVE system was approximately 75% operational The system was down for four days between March 27 and April 1 and for one day on July 14 for unknown causes, likely due to power failures The SVE was intentionally shut down on May 2 through May 19 to allow the vadose to return to atmospheric pressure and allow volatile ' contaminants to equilibrate in the vadose zone(surging the system) The SVE system was also down between June 24 and 26 when the TCAT 500 scfin catalytic oxidizer was switched out with a 300 scfin blower using granular activated carbon (GAC) as the abatement device Details of surging the ' system are presented in the following paragraph In accordance with the Secor Work Plan for Remedial Approach and Well Installation dated May 2, 2002, the TCAT 500 Catalytic oxidizer was scheduled to be replaced with a skid mounted SVE blower unit that uses GAC The primary reason for the switch from the catalytic oxidizer to GAC was to reduce operating costs The cost to operate the catalytic oxidizer exceeds the cost to utilize GAC to remove contammants from the influent provided the mass loading of contaminants does not necessitate excessive GAC change outs For GAC O&M costs to exceed that of the catalytic r oxidizer, a GAC change out frequency of less than two months (using 2,000 pound GAC vessels) would be required By May 2003, the contaminant concentrations in the vapor influent and the measured flow rates equated to a mass loading that would Justify switching the SVE system to GAC To ensure that the contaminants in the vadose zone had reached equilibrium, the SVE system was ' shut down for a period of 17 days to allow the vadose zone to return to typical atmospheric pressure and allow vapors to disperse (equilibrate) throughout the vadose zone At the end of the shut down, the SVE system was restarted and vapor Influent samples were collected at the following intervals 1 58643 06-01 -5- July 25 2003