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Updated Site Conceptual Model and Fourth Quarter 2002 Monitormg and Remediation Report Cleanup and Abatement Order No 5-00-707 EAI Prosect No 1232 4.4 REMEDIATION SYSTEM STATUS REPORT Only low VOCs concentrations were observed in extracted soil vapor during the third quarter 2002 Therefore, the thermal oxidizer was operated on only a limited basis (220 hours) during the fourth quarter 2002 However, the air sparging system was operated for approximately 1,471 hours during the current quarter The system was operated alternately between Wards and Unocal sites for one week periods All vapor extraction wells were open to the remediation system except wells VEW-5 and VEW-10 The thermal oxidizer was operated for approximately five days in November 2002, ternunating operation for the month on November 27, 2002 After completion of ground water monitoring, the oxidizer was restarted on December 11, 2002 and VOC readings were obtained from ' individual vapor extraction wells using an OVA calibrated against methane (see Table 5) As required by conditions of the air quality permit, quarterly air emission sampling was performed on December 12, 2002 Soil vapor samples were obtained for quarterly emissions monitoring from the thermal oxidizer inlet and exhaust Inlet samples were obtained from wells on both the Wards and Unocal sites The samples were analyzed for TPH-G, BTEX, and MTBE by EPA Methods 8015M and 8021B, and for carbon dioxide, methane, and oxygen by ASTM-D 1946 No hydrocarbons above the laboratory detection limit were detected in inlet samples to the oxidizer from either the Wards or Unocal sites (see Appendix C) The soil vapor sample obtained from the Wards and Unocal sites contained 0 21% (sample OX- in-1B, Appendix C) and 176% (sample OX-in-2B, Appendix C) carbon dioxide, respectively These data indicate that hydrocarbons in the subsurface are subject to biodegradation Since starting the remedial system, the thermal oxidizer has operated for a total of 5,974 hours and the sparging compressor has operated for 9,693 hours, removing approximately 8,456 pounds of petroleum hydrocarbons from impacted soil and ground water The amount of biodegraded hydrocarbons is difficult to calculate and is not included in this total The remediation system "Operating Parameters" and "TPH Removal and Destruction Efficiency" data are presented in Tables 6 and 7, respectively i siiM WORD 1232Ra2D1 -7- EAWRONMENTALAUDIT,INC