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Ripon Farm Service Page 2 '
<br /> 932 Frontage Road March 3, 2010
<br /> Ripon, California 95366
<br /> The EHD also requested by letter dated September 23, 2009, a response to several concerns
<br /> numerically summarized below:
<br /> 1. Address the detection of 9,000 milligrams per kilogramF(mglkg) of TPH quantified as diesel
<br /> (TPH-d) in soil samples collected from borehole B8 since this concentration is well above
<br /> the ESL for TPH-middle distillates established by the CRWQCBSFBR for gross
<br /> contamination and direct exposure.
<br /> Although AGE did not comment in the NFAR concerning}ithe 9,000 mg/kg TPH-d, AGE did
<br /> respond by electronic mail dated September 29, 2009, .in which AGE noted that the soil
<br /> samples were collected from. borehole B8 in 1994 at twenty feet below surface grade (bsg),
<br /> indicating a deep soil impact, not a shallow soil impact. AGE also noted that shallower soil
<br /> samples from borings in the immediate area (612, MW-3, 117, B$ and MW-5) were much less
<br /> intensely impacted. Benzene, toluene, ethylbenzene, and total xylenes (BTEX) compounds
<br /> were usually not detected and were at low concentrations when detected. A grab
<br /> groundwater sample from boring B-13, near the Jimco Truck Plaza (Jimco) above-ground
<br /> storage tanks (ASTs), was intensely impacted by TPH-d [450,000 micrograms per liter(pg/L)]
<br /> but not by BTEX. AGE attributes the 138-20 data to the unauthorized release from Jimco's
<br /> ASTs, to which the EHD concurs. Intuitively, at twenty feetlbsg the health risk posed by direct
<br /> contact would not be great under normal circumstances. The EHD considers the very low to
<br /> f non-detectable impact to groundwater in the area (MW-1, MW-2, MW-3 and MW-5) to
<br /> demonstrate that gross contamination is not likely to.be an issue related to the 138-20 data.
<br /> 2. Soil gas samples were analyzed for TPH-g by method, TO-3; and other contaminants of
<br /> concern (including BTEX, methyl tertiary-butyl ether '(MTBE), ethyl tertiary-butyl ether
<br /> (ETBE), tertiary-butyl alcohol (TBA), tertiary-amyl methyl ether(TAME), di-isopropyl ether
<br /> (DIPS), 1,2-dichloroethane (1,2-DCA), 1,2-dibromoethane (EDB) and isopropyl alcohol
<br /> E (IPA), the leak-check compound, were analyzed by method ATO-15, as submitted by Cal
<br /> Tech Environmental Laboratories (Cal Tech). The associated quality assurance/quality
<br /> control data for method blanks, and matrix:spikelmatrix spike duplicates, were submitted
<br /> using a water matrix and methods 8015M for TPH ',g, and 8260B for,the 'remaining
<br /> contaminants of concern. Please clarify whether vapor-phase calibration standards were
<br /> used to generate the initial calibration and daily calibration check associated with these
<br /> soil gas samples. If water-phase calibration standards were used instead of vapor-phase
<br /> calibration standards, then the laboratory report for the'soil gas samples must be revised
<br /> and resubmitted.
<br /> AGE responded to the above concern by submitting a letter dated September 25, 2009, from
<br /> Cal Tech whereby Cal Tech compared the similarities and differences between Environmental
<br /> Protection Agency (EPA) method 8260B and.EPA methods TO-14A and TO-15. However,
<br /> Cal Tech did not address whether vapor-phase calibration•i standards were used to generate
<br /> the initial calibration and daily calibration check associatedwith the soil gas samples reported
<br /> by methods TO-3 and TO-15. EPA method TO-15 reguires�`vapor.„phase calibration standards
<br /> to generate the initial calibration and daily calibration check. If water-phase calibration
<br /> standards were.used instead of vapor-phase calibration standards, then the laboratory report
<br /> for the soil gas samples must be revised and resubmitted to reflect the appropriate method
<br /> used to analyze the soil gas samples. Simply asked, were vapor-phase calibration standards
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