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Mr. M. Scott Mansholt—CEM • <br /> ' Addendum to the Work Plan for Additional Site Characterization <br /> Mountain House Development Site#3 October 5, off <br /> Page 3 of 3 <br /> 1 potable), SAIC will request Lancaster to report benzene, toluene, ethylbenzene,and total xylenes, <br /> PAHs, and TPHd results using detection limits that are lower than the RWQCB WQOs and other <br /> health-based and aesthetic standards of the RWQCB and the EPA(to the extent practicable). <br /> ' Because the PAH concentrations are greater than those typically encountered at Chevron HPP <br /> sites, a soil or groundwater sample will be submitted to Chevron Energy and Technology <br /> Company for a fingerprint analysis using gas chromatography/mass spectrometer(full-scan) to <br /> ' evaluate whether the petroleum encountered at the site consists of historic San Joaquin Valley <br /> crude oil,bunker fuel, or petroleum products of third-party sources. <br /> 1 ADDITIONAL INFORMATION <br /> In addition to providing a schedule for the additional site characterization, the Scheduling Plan <br /> addressed RWQCB concerns about the laboratory-measured pH level of the groundwater sample <br /> collected from soil boring MH3-2, which may have had its preservative displaced in the field. In <br /> order to resolve the issue, additional soil and groundwater samples in the vicinity of soil boring <br /> MH3-2 will be collected,as recommended by the RWQCB. <br /> 1 SAIC will perform this investigation in general accordance with the RWQCB-approved <br /> Technical Approach to Site Evaluation and Decision-Making, Historical Pipeline Portfolio, <br /> Central Valley Region(referred to as the "CTA"), dated February 2005. The CTA serves to <br /> 1 guide decision making during soil and groundwater investigations. <br /> Also, for the purposes of a site-specific HHRA, soil samples will be collected from the upper <br /> ' 10 feet of each boring. HHRA soil samples will be collected and tested in accordance with the <br /> specifications of the CTA. <br /> Sincerely, <br /> 1 SCIENCE APPLICATIONS INTERNATIONAL CORPORATION <br /> * 0-(2Z)b � <br /> 1 Jeffrey D. White Michael Hurd, CHG 0068 <br /> Senior Project Manager Senior Project Manager <br /> 1 Enclosures: <br /> Figure 1: Site Vicinity Map <br /> i ial.=L fi0ii9 <br /> 1 Figure 2: Site Map with Proposed Soil Boring Locations <br /> Table 1: Water Supply Well Search «• t'''-G8 <br /> Table 2: <br /> Proposed Boring Objectives <br /> i_aw.L•Lbai$T <br /> ' \Xp.9oSG� <br /> OF C_ <br /> 1 <br />