SITE INFORMATION AND CORRESPONDENCE

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Site-Wide Comprehensive ROD 11- 1 May 1997 DDRW Tracy Institutional controls is not a "no action" alternative. The cleanup levels presented in Section 8 (Table 8-8) of the RI/FS Report must be included as part of the selected remedy for this site. The ROD should state that the selected remedy will include re-evaluating the remedial alternatives to consider active remedial action if and when ground water monitoring (also included as part of the selected remedy) indicates an impact from CoCs present in soil at the site (specific"trigger" language should be presented) . 5. SWMU 8: The ROD should clarify that the selected remedy for this site includes collecting soil-gas samples for VOCs as part of the final round of confirmation sampling program for the excavation activities. Further text should speci5y that the technical and economic feasibility to remediate any VOC soil contamination will be assessed based on the soil-gas results as part of completing the remedy (also see general comments 47 & 8). Section 9.5.4.2 should include text to clarify that the limits of the disposal area are well-defined, and soils will be removed to the depth of the water table during remediation. 6. SWMU 20/23: The site characterization should list PCE as a contaminant in groundwater and soil. The ROD should specify that the selected remedy for these sites includes conducting pre-design soil- gas sampling and evaluation of the results. Text should be added to specify the conditions (i.e., concentrations detected above soil-gas cleanup levels) for expanding the areas of soil vapor extraction as part of the selected remedy (see general comments#7 & 8). The text should also clarify that areas associated with SWMU 33 (IWPL), including SB108 (Area 1/Building 10) and SB431 will be assessed and remediated based on the review of soil-gas data collected as part of this remedy (see general comment 47 & 8). 7. SWMU 24: The ROD should specify that the selected remedy includes conducting pre-design soil- gas sampling and evaluation of the results. Text should be added to specify the conditions(i.e., concentrations detected above soil-gas cleanup levels), including a technical and economic feasibility analysis, for implementing soil vapor extraction,-or other treatment technology to address soil vapor contamination as part of the selected remedy. Section 9.5.6.3 discusses how monitoring of LM I8AA will be used to assess the"natural attenuation of petroleum hydrocarbons in ground water" at this site. The ROD should clarify the impacts to groundwater from contaminants at SWMU 24 and specify how this groundwater contamination will be addressed, as part of a selected ground water remedy (see general comment 45). Section 10.10 incorrectly states that"Pre-design soil-gas sampling will be conducted to determine whether bioventing or SVE is more effective." The ROD should be modified to accurately state that SVE may be implemented before bioventing to meet VOC cleanup levels depending on evaluation of the results of the pre-design soil-gas sampling, including any technical and economic feasiblity analysis. 8. SWMU 27. The ROD should clarify that the selected remedy includes completing the characterization of soil contamination as part of the excavation activities.