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0 0 <br /> James L. Tjosvold, P.E. <br /> August 19, 1996 <br /> Page 8 <br /> FS. Surface soil samples were collected from five off-site locations and subsurface <br /> soil samples were collected from two off-site boreholes. The range of background <br /> values from literature for metals concentrations in soil and groundwater from the <br /> San Joaquin region were also summarized. Background water quality data were not <br /> measured locally near the site but instead were obtained from literature. <br /> Comment: <br /> 4. Page 3-6, Section 3.1.3, Supplemental Soil Investigation <br /> The summary states that results from the field screening analyses did not correlate well with <br /> laboratory analytical results and the soil operable unit feasibility study (OUFS) will use only <br /> laboratory data. It is unclear if sufficient soil samples were taken for laboratory testing to <br /> characterize the investigated areas. <br /> Response: <br /> 4. More than twice the planned number of soil samples were submitted for <br /> laboratory analysis. These data, in conjunction with field observations, collected <br /> during drilling were sufficient for source area delineation. Please see the response <br /> to DTSC's comment#5. <br /> Comment: <br /> 5. Page 4-1, Section 4, Overview of Site Conditions <br /> This section should include a summary of the background soil investigation. The summary <br /> should provide the rationale for sample location and number and discuss the results, <br /> particularly how background levels were established. <br /> Response: <br /> 5. Section 5 of The Final Remedial Investigation and Risk Assessment Report (submitted <br /> to the agencies on August 6, 1993) included a detailed discussion of background soil <br /> and groundwater concentration determination. This discussion will be summarized <br /> in the combined soil and groundwater FS. <br /> Comment: <br /> 6. Page 4-1, Section 4.1.2, Area II Surface Soils <br /> The first paragraph describes polynuclear aromatic hydrocarbon (PNA) concentrations being <br /> in the range of background concentrations. This statement is related to Specific Comment <br /> No. 5 and should be clarified because the background concentration for chemicals which do <br /> not occur naturally should be zero. <br /> The subsequent paragraphs describe the presence of arsenic (1.5 to 231 mg/kg), copper (11.3 <br /> to 1,480 mg/kg), lead (4.9 to 1,268 mg/kg), and PCBs (<2 to 81 mg/kg) in Area II's surface <br />