SITE INFORMATION AND CORRESPONDENCE

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Mr. Jerry Lile July 17, 2000 Page 4 AREA 11 6) The detection of B(a)P at a concentration greater than the industrial soil PRG in the 1-foot soil sample from 11B-13 is of potential concern. The B(a)P has been defined to the south and southwest but higher concentrations may be present in a northern direction from the location of boring 11 B-13. It is also possible that lower or non-detect concentrations could occur in the northern direction. If the original source for PAHs is contaminated fill used during grading it would not be unreasonable to expect random high hits of B(a)P across the site. Recommendation Consideration should be given to potential data needs for completing an adequate risk assessment that may be based on a statistical analysis of detections across the site. It may be necessary to assess soil quality to the north of 11 B-13 to accurately address risk that would be the result of exposure to B(a)P. 7) Detected concentrations of diesel in groundwater may exceed beneficial use limit for diesel that may be required by the RWQCB. Recommendation The GSU recommends, that if not as of yet already done, consult with the RWQCB to determine if beneficial limits apply to this site and if there will be any other requirements, such as assessing the leachability potential and/or semi- annual groundwater monitoring. Area 20 8) Page 28, second paragraph: It is reported that all arsenic concentrations for soil samples collected from Area 20 are below the California hazardous waste criteria of 500 mg/kg or the PRG for industrial sites of 440 mg/kg. However the carcinogenic PRG concentration for arsenic at industrial sites is 3 mg/kg. Recommendation Consideration should be given to the appropriateness of using the carcinogenic PRG for arsenic. CiOFFICE\WPWIN\WPOOCS%WPSUITE\NORSHRI.WPO