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Ms. Carol Campagna -2 - 10 June 2009 <br /> Shell Stockton Terminal 0 0 <br /> 2. We cannot presently concur with the strategy Shell has proposed for calculating <br /> background concentrations. The California Code of Regulations (CCR), Title 27, Section <br /> (Q 20415(e)(7)(B) requires the discharger to submit documentation of the proposed data <br /> analytical methods prior to implementing the background study. We anticipate that <br /> background and intraplume concentrations of some constituents of concern (CDCs), such <br /> as petroleum hydrocarbons, will not require updating since an extensive database of these <br /> constituents exists. However, due to a lack of non-COC data that is required for the <br /> background study, we expect that these data will be contemporaneous and therefore will <br /> require updating. By 6 July 2009, Shell needs to submit the proposed data analytical <br /> method before implementing the background study. Allowable data analytical methods are <br /> listed in CCR, Title 27 � 20415(e)(8)(A-E). <br /> 3. The text in the second paragraph on page 2 of the Response which states "...further <br /> variation is expected via remediation in the future." This suggests that a factor that will <br /> determine whether data will require updating will depend on concentration variability in <br /> response to remediation. We suspect that Shell applied this condition based on its <br /> interpretation of CCR, Title 27 � 20415(e)(1 0)(B). To clarify, that section of the CCR is not <br /> intended to address variability caused by remediation. It is intended to address natural <br /> groundwater parameter concentration fluctuation occurring independent of remedial <br /> activities. Shell's proposal to adjust initial intraplume conditions in response to remedial <br /> activity is counterproductive because the intent of remediation is cause variability in COC <br /> concentrations, preferably as a decreasing trend. By 6 July 2009, we request that Shell <br /> submit a list of constituents that will require updating to calculate background conditions. <br /> Based on groundwater data that currently exist for the Site, these data should be limited to <br /> the line items that follow dissolved lead in the table on Page 2 of the Response. <br /> 4. We concur with Shell's proposal to evaluate the feasibility of using 21 injection points by <br /> numerical modeling. We anticipate that the model will be performed by using a well- <br /> documented application, such as Visual Modflow, to prepare a flow model. <br /> In summary, by 6 July 2009, please submit the proposed data analytical method for the <br /> background study and a list of constituents that will require-updating to calculate background <br /> conditions. If you have any questions regarding this letter, you may contact me at (916) 464- <br /> 4811 or betaylor@waterboards.ca.gov. <br /> BRIAN TAYLO , R. <br /> Engineering Geologist <br /> cc: Ms. Margaret Lagorio, San Joaquin County Environmental Health Department, Stockton <br /> Mr. Jeff Gaardner, Conestoga-Rovers and Associates, Sonoma <br /> Mr. Jeffery D. Wingfield, Port of Stockton, Stockton <br /> Mr. Ron Orallo, Shell OPUS, Stockton <br /> Mr. Mark O'Brien, ERS, Alamo <br /> Mr. Sean Coyle, Stantec Consulting Corp., Rancho Cordova <br /> Ms. Shelby Lathrop, ConocoPhillips, Sacramento <br />