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Ms. Shelby Lathrop - 3 - 31 December 2008 <br /> Former Tosco Bulk Terminal No. 10013 <br /> 4. During our August meeting, ConocoPhillips stated that its optimization options included the <br /> potential use of a stronger oxidant, such as hydrogen peroxide. Given that the results of the <br /> pilot study yielded no clear DO or petroleum hydrocarbon concentration trends that indicate <br /> the bottled oxygen injection was conclusively effective, ConocoPhillips needs to explain why <br /> it recommends the continued use of bottled oxygen instead of a skid-mounted oxygen <br /> injection system, or alternatively, a stronger oxidant. <br /> 5. Although not specifically discussed in the Work Plan, ConocoPhillips' rationale for converting <br /> well MW-22C appears to be an attempt to inject oxygen into the C zone to address the <br /> petroleum hydrocarbons in the deep downgradient portion of the plume. Use of the inflatable <br /> packers may be an effective solution for targeting a specific water bearing zone. However, <br /> we are concerned about the potential for damaging the well screens by inserting packers <br /> and about the potential for short circuiting of the injected oxygen through nearby wells <br /> MW-20 and MW-21 B. ConocoPhillips needs to discuss the potential for these two concerns <br /> to occur and how they may be avoided. <br /> 6. ConocoPhillips cites the successful implementation of an alternative remedial process as the <br /> rationale for seeking the Regional Water Boards' concurrence in dismantling and removing <br /> the idle hydrogen peroxide and ozone (HiPDX) pump and treat system from the Site. The <br /> Work Plan does not specify which successful alternative remedial process ConocoPhillips <br /> has implemented. In our June 2006 letter, Regional Water Board staff commented that we <br /> did not concur with ConocoPhillips' decision to discontinue use of this treatment technology. <br /> Since ConocoPhillips has not identified a permanent remedy with which we have concurred, <br /> our June 2006 comment will continue to serve as our position on the matter of groundwater <br /> remediation at this Site. However, since the equipment and remediation compound are no <br /> longer being used for their intended purpose, the decision regarding whether or not to keep <br /> them on site is an internal matter that does not require the Regional Water Board staff's <br /> approval. <br /> We cannot concur with the Work Plan until ConocoPhillips addresses Comments 1 through 5 <br /> presented above. Please provide a response to comments by 30 January 2009. <br /> If you have any questions regarding this letter, you may contact me at (916) 464-4811 or <br /> betaylor@waterboards.ca.gov. <br /> BRIAN T <br /> Engineering Geol.. ist <br /> cc: Mr. Harlin Knoll, San Joaquin County Environmental Health Department, Stockton <br /> Mr. Richard Stiffler, City of Stockton — Department of Municipal Utilities, Stockton <br /> Ms. Debbie Callie, Port of Stockton, Stockton <br /> Mr. Mark O'Brien, Port of Stockton/ERSC, Alamo <br /> Mr. Jeff Kasper, Deputy Port Director, Environmental Planning & Facilities, Stockton <br /> Mr. Sean Coyle, Stantec, Rancho Cordova <br /> Mr. Joe Aldridge, NuStar Energy, Texas <br /> Ms. Carol Campagna, Shell OPUS, Carson <br />