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Californi gional Water Quality Cor A Board =E'`•.,'`. �F <br /> s; <br /> Central Valley Region W ' <br /> Katherine Hart, Chair a <br /> 11020 Sun Center Drive,4200,Rancho Cordova..California 95670-61 14 <br /> Matthew Rodriquez (916)464-3291 • FAX(916)464-4645 Edmund C.Brown Jr. <br /> S'ecretar)'jor http://www.waterboards.ca.gov/centralvalieNGovernor <br /> Governor <br /> (`J` \�(/ <br /> Environmental Protection <br /> 12 January 2012 JAN 17 2012 <br /> ENVIRONMENTAL HEALTH <br /> PERMIT/SERVICES <br /> Ms. Shelby Lathrop <br /> ConocoPhillips Company <br /> 76 Broadway <br /> Sacramento, CA 95818 <br /> FORMER TOSCO BULK TERMINAL #10013, 3505 NAVY DRIVE, STOCKTON, SAN <br /> JOAQUIN COUNTY <br /> California Regional Water Quality Control Board — Central Valley Region (Central Valley Water <br /> Board) staff reviewed the following documents: <br /> • 31 October 2011 Response to Comments associated with Human Health Risk <br /> Assessment (Letter) <br /> • 31 October 2011 Third Quarter 2011 Status Summary Report (QMR) <br /> ATC Associates prepared the documents on behalf of ConocoPhillips for the former Tosco <br /> bulk fuel terminal at 3505 Navy Drive in Stockton (Site). ConocoPhillips conducts groundwater <br /> monitoring at the Site in accordance with Monitoring and Reporting Program (MRP) <br /> No. R5-2004-0824. In 2005, Valero (currently named as NuStar Energy) purchased the Site <br /> and is the current Site operator. Since 1998, the Site has been used solely to store diesel <br /> fuel. <br /> The Letter updates information included in the 9 August 2011 Human Health Risk Assessment <br /> (HHRA). ConocoPhillips reviewed the historical soil data and concluded that remaining soil <br /> concentrations that exceed the commercial worker screening level are within the existing tank <br /> farm. In addition, on 1 July 2011 ConocoPhillips collected soil vapor samples to evaluate the <br /> indoor air pathway for preparation of the HHRA. Soil vapor sample SG-3 contained water in <br /> the sampling tube and ConocoPhillips was unable to collect an adequate sample volume. The <br /> Letter states that because the other two sample locations were located in the source area and <br /> did not contain concentrations above the screening levels it is not necessary to resample at <br /> SG-3. <br /> The QMR includes a summary of the third quarter 2011 sampling event. The maximum <br /> concentrations of total petroleum hydrocarbons as gasoline (TPHg), TPH as diesel (TPHd), <br /> methyl tert butyl ether (MTBE), and tert butyl alcohol (TBA) detected in groundwater during the <br /> third quarter sampling event were 39 microgram per liter (pg/L), 270 pg/L, 7.8 pg/L, and <br /> 56 pg/L, respectively. The QMR requests the Site be considered for Closure. <br /> California Environmental Protecting .gadget' <br />