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be similar because dissolved petroleum hydrocarbons greater than C24 are not likely present in <br /> groundwater. The extraction methods used for the TEPH and TPHd analyses are different but <br /> both are EPA approved methods, Method 3510C is used on groundwater samples containing <br /> sediment and Method 3520 is used on sediment-free water samples. The analyses for BTEX at <br /> both properties were the same (the EPA periodically updates method numbers to reflect <br /> modernization of instrumentation, hence 8020 is now 8021B). The analyses for PAHs were <br /> different in that a new method (8270 SIM) was developed following the Dividend investigation <br /> that allowed for lower detection limits than method 8310. However, it should be noted that <br /> method 8270 is one of the approved methods listed in the Consistent Approach <br /> If you have any questions or require additional information, please call Elizabeth Lu at(925)842- <br /> 6855. <br /> Sincerely, <br /> K.L. Hower <br /> Project Manager <br /> California Site Remediation <br /> Attachment: Figure 2: Groundwater Analytical Results <br /> cc: Ed Griswold— Surland Homes <br /> Michael Keim—Geomatrix Consultants,Inc. <br /> Elizabeth Lu—CPL/Geomatrix Consultants, Inc. <br />