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Stantec <br /> April 30, 2010 <br /> Page 3 of 4 <br /> Reference: First Quarter 2010 Site Status, Groundwater Monitoring and Remedial Summary Report- <br /> Stockton Terminals Technical Committee Facilities <br /> Appendix K-Ozone Injection Well Monitoring Program and Revised Contingency Plan <br /> TRIGGER WELL COMPLIANCE LIMITS <br /> Constituent Water Quality Source Compliance <br /> Objective Limit in µglL <br /> Benzene Chemical Constituents OEHHA 0.15 (0.5 default level) <br /> Ethylbenzene Chemical Constituents USEPA 29 <br /> Toluene Chemical Constituents USEPA 42 <br /> Xylenes Chemical Constituents USEPA 17 <br /> MTBE Chemical Constituents CA DHS, 5.0 <br /> Secondary MCL <br /> Note: The default compliance limit for benzene is the method reporting limit of 0.5 fag/L per RWQCB <br /> electronic communication dated January 6, 2005. Per the RWQCB December 15, 2008 letter, TBA is not <br /> a compliance analyte for the Trigger Wells. <br /> CONTINGENCY PLAN LANGUAGE <br /> The revised contingency plan language below includes the original language from SECOR's <br /> June 27, 2003 Response and Addendum. It has been revised to include RWQCB-requested <br /> modifications as outlined in Stantec's November 7, 2008 Revised Contingency Plan and <br /> RWQCB's December 15, 2008 Letter. <br /> The following contingency plans are proposed if trend analysis confirms that the plume has <br /> been cut-off and the results of the MNA study indicate that natural biodegradation will not occur <br /> at a sufficient rate to destroy remaining petroleum hydrocarbons and MTBE down-gradient of <br /> the proposed "A" and "B" zone ozone well remediation systems. <br /> REMEDIAL OBSERVATION WELLS CONTINGENCY PLAN <br /> If concentrations of compliance analytes have increased by one order of magnitude over <br /> historical concentrations for three consecutive quarters in remedial observation wells <br /> PS/MW-18, PS/WC-1S, AR/MW-21A, AR/MW-18B, AR/MW-21B, and PS/WC-1 M, a second <br /> ozone sparge array will be installed east of those wells to destroy the remaining petroleum <br /> hydrocarbons and MTBE. The ozone wells will be constructed as proposed in the CAP and will <br /> be connected to the ozone sparge remediation system for the initial ozone well array. <br />