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ARCADIS Mr. Roberto Cervantes <br /> September 7, 2010 <br /> well, rather than a typical 2"monitoring well, would be better suited for such testing." <br /> Response to Comment#3 <br /> We concur that additional groundwater monitoring wells may need to be installed at <br /> the Site in the future, pending the results of the proposed investigation. The goals of <br /> the four proposed groundwater monitoring wells are (1) to evaluate the shallow <br /> groundwater gradient and flow direction, and (2) to provide information on COC <br /> concentrations at the site boundary. The only currently available groundwater data <br /> are based on grab groundwater samples that were collected more than eight years <br /> ago. The proposed investigation will provide valuable information that will help <br /> delineate the current distribution of CDCs at the Site and inform decisions regarding <br /> the potential need for, and locations of, additional groundwater monitoring wells at <br /> the Site. <br /> Comment#4 <br /> "The work plan proposes to test for CAM 17 metals, TPH, and fuel oxygenates. Fuel <br /> oxygenates will be analyzed for using EPA Method 8260. Chevron should perform <br /> some limited testing for a full range of VOCs and SVOCs. While lead is an analyte in <br /> the CAM 17 metals, Chevron needs to analyze samples for lead with a lower <br /> detection limit than EPA Method 6010 provides. For example, Method 6010 has a <br /> lead detection limit of 3 Ng/L in water. The California Public Health Goal is 0.20 pg/L <br /> in water. Also, tetraethyl lead(a former gasoline additive) has an IRIS reference dose <br /> of 0.0007 pg/L in water. EPA Method 6020 has a detection limit of 0.25 Ng/L for lead <br /> in water. Chevron should analyze the soil and groundwater samples for lead using <br /> EPA Method 6020. Naphthalene is a commonly encountered constituent of concern <br /> at bulk fuel facilities. Chevron needs to analyze the soil and groundwater samples for <br /> naphthalene in addition to the previously mentioned analytes. <br /> Response to Comment#4 <br /> We concur with the requested modifications to the proposed analytical methods <br /> specified in Comment #4. Approximately 20% of the proposed soil and groundwater <br /> samples will be analyzed for the full range of volatile organic compounds(VOCs) and <br /> semivolatile organic compounds (SVOCs) using United States Environmental <br /> Protection Agency(EPA) Methods 8260 and 8270, respectively. Lead concentrations <br /> in groundwater samples will be analyzed using EPA Method 6020, rather than EPA <br /> Method 6010. Naphthalene will be analyzed in soil and groundwater using EPA <br /> Method 8270. <br /> Page: <br /> rtoSI W P-San Jose St-Sep 10-B0040810 doc 3/5 <br />