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Ms. Shelby Lathrop -2 - 13 September 2011 <br /> Former Tosco Bulk Terminal, <br /> 3505 Navy Drive, Stockton, San Joaquin County <br /> would need to be removed for the pathway to be complete. Surrounding properties are <br /> supplied water by the municipality and the risk of ingestion of contaminated groundwater, <br /> therefore, is low. ConocoPhillips also conducted a Tier 2 risk assessment for soil vapors to <br /> evaluate the potential for vapor intrusion. ConocoPhillips concluded that there was no vapor <br /> intrusion risk to the residential scenario. In addition, ConocoPhillips estimated that the Site <br /> groundwater will reach WQOs within five to 10 years. <br /> Our comments are: <br /> 1. The HHRA does not include a map showing the locations of the soil samples listed in <br /> the soil data table. ConocoPhillips states that TPHd, TPHg, BTEX, and MTBE exceed <br /> the exposure concentration for future potential construction worker/trench worker. By <br /> 14 October 2011, ConocoPhillips needs to include a Site map showing the locations of <br /> all soil samples collected at the Site. In addition, ConocoPhillips needs to show the <br /> locations of soil samples that exceed the ESLs and evaluate the construction worker <br /> exposure pathway. <br /> 2. The HHRA does not include any information on why the soil vapor sample was not <br /> collected at SG-3. Soil gas sampling point SG-3 is downgradient of the Site near <br /> monitoring well MW-20. By 14 October 2011, ConocoPhillips needs to notify Central <br /> Valley Water Board staff of the reasons why this soil gas sample was not collected and <br /> recommendations for additional sampling, if necessary. <br /> 3. The QMR does not include isoconcentration contours for the contaminants of concern <br /> at the Site. The MRP requires ConocoPhillips to prepare isoconcentration contour <br /> maps for each report. The next monitoring report is due 1 November and needs to <br /> include isoconcentration contour maps. <br /> In summary, by 14 October 2011 ConocoPhillips needs to submit a Site map showing the <br /> location of all soil samples and a summary of locations that exceed the soil ESLs. Once we <br /> have the requested information, we will be able to evaluate the site for no further action. In <br /> addition, future groundwater monitoring reports need to include trend graphs, estimates of <br /> when wells will reach WQOs, and isoconcentration contours for contaminants of concern. If <br /> you have any questions regarding this letter, you may contact me at (916) 464-4819 or by <br /> email at ksheltonCcDwaterboards.ca.gov. <br /> KRISTI SHELTON, P.E. <br /> Water Resources Control Engineer <br /> Aboveground Tanks Cleanup Unit <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. Gabe Stivala, ATC, North Highlands <br /> Mr. Joe Aldridge, NuStar Energy, Texas <br /> Ms. Carol Campagna, Shell OPUS, Carson <br />