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Ripon Farm Service Page 2 <br /> 932 Frontage Road September 23, 2009 <br /> Ripon, California 95366 <br /> • Concentrations of TPH quantified as diesel (TPH-d) were detected at 9,000 milligrams per <br /> kilogram (mg/kg) in soil samples collected from borehole B-8. This concentration is well <br /> above the ESL for TPH (middle distillates) for gross contamination and direct exposure. <br /> This evaluation was omitted from the report and must be appropriately addressed in the <br /> site closure summary. <br /> • Soil gas samples were analyzed for TPH-g by method TO-3, and the remaining <br /> contaminants of concern listed above were analyzed by method TO-15, as submitted by <br /> Cal Tech Environmental Laboratories. The associated quality assurance/quality control <br /> data for method blanks, and matrix spike/matrix spike duplicates, were submitted using a <br /> water matrix and methods 8015M for TPH-g, and 8260B for the remaining contaminants of <br /> concern. Please clarify whether vapor-phase calibration standards were used to generate <br /> the initial calibration and daily calibration check associated with these soil gas samples. If <br /> water-phase calibration standards were used instead of vapor-phase calibration <br /> standards, then the laboratory report for the soil gas samples must be revised and <br /> resubmitted. <br /> • Soil gas samples were not analyzed for TPH-d by method TO-17, an inconsistency with <br /> the work plan approved by the EHD by letter dated August 27, 2008. TPH-d has <br /> historically been detected at significant concentrations in soil and groundwater collected <br /> during previous investigations at this site. A rational must be provided for not analyzing <br /> soil gas samples for TPH-d by method TO-17 that includes demonstrating that the <br /> reported results are equivalent to those that would have been provided by method TO-17 <br /> and can be relied upon for decision making. <br /> In addition to addressing the concerns listed above, please include estimates of the residual <br /> benzene, TPH-g, TPH-d, and 1,2-DCA masses in soil and groundwater when submitting the site <br /> closure summary. If you have any questions concerning this letter, please contact Vicki <br /> McCartney at (209) 468-9852, or by email at vmccartney@sjcehd.com. <br /> Sincerely, <br /> Victoria L. McCartney, REHS Nuel C. Henderson, Jr. PG <br /> Senior Registered Environmental Health Specialist Engineering Geologist <br /> c: Mr. William R. Little, PG, Advanced GeoEnvironmental, Inc. 837 Shaw Road, Stockton, <br /> California 95215 <br /> Mr. James L.L. Barton, PG, California Regional Water Quality Control Board Central Valley <br /> Region, 11020 Sun Center Drive, Suite 200, Rancho Cordova, California 95670 <br />