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Mr George Takemon Project OF90-002 04 August 21, 1995 ' Page 4 Analytical Methods and Results Water samples collected from wells MW-9 through MW-11 and MW-14 were analyzed for TPHG using modified EPA Method 5030/DHS LUFT and for BTEX using EPA ' Method 5030/8020 Samples were analyzed at Columbia Analytical Services, Inc , in San Jose, California (California Department of Health Services Hazardous Waste Testing Laboratory Certification No 1426) Copies of the chain-of-custody records and laboratory ' analysis reports are presented in Appendix C Analytical results are summarized in Table I ' The results of laboratory analyses indicated TPHG and BTEX were not detected in groundwater samples collected from wells MW-9 through MW-11 TPHG and benzene were detected in the sample from well MW-14 at concentrations of 2,500 and 320 parts per bdhon (ppb), respectively Concentrations of TPHG and benzene are shown on Figure 2 OPERATION AND MAINTENANCE EMCON began the operation and maintenance of the remediation system in April 1995 The remediation system consists of an EI 260 thermal oxidizer fitted with a catalytic insert ' and rated at 250 cfm, and a vacuum blower The remediation system operates under a permit to operate issued by San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD), No N-841-2-0 The blower extracts soil vapors from wells MW-13 and MW-14 Extracted soil vapors are combusted in either thermal or catalytic mode prior to discharge to the atmosphere The remediation system is currently operating in the catalytic mode An air sparge well (AS-1) was installed on May 8, 1995, to volatilize the dissolved ' phase petroleum hydrocarbons from the groundwater An air sparge blower was installed and started up on June 19, 1995, injecting air at the rate of 5 cfm into the groundwater The radius of influence of the SVE system was estimated to be 77 feet, per the previous ' consultant (First Quarter 1995 Status Report, Anderson Consulting) In May 1995, EMCON collected induced vacuum data to estimate the radius of influence The current ' radius of influence for the SVE system was estimated to be 65 feet During the second quarter of 1995, a technician from EMCON conducted three monthly site visits During the site visits, system operational parameters were monitored (see field data sheets in Appendix D), and air samples were collected in April and June 1995 for laboratory analysis (see analytical reports and chain-of-custody records in Appendix C) During May 1995, the remediation system was monitored using a flame ionization ' detector as required by the permit to operate Tables 2, 3, 4, and 5 summanze the system performance in the second quarter of 1995 Figure 4 shows the cumulative mass of petroleum hydrocarbons extracted over time SAON\PJU0F9=F900020 4cs-95 PAS 2