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unquantifiable VOC losses can occur during sampling and during sample transfer steps prior to <br /> analysis." It is noted that some models have been used to evaluate the partitioning of VOCs into <br /> its four phases and then integrating the phased data into an estimation of bulk soil concentration. <br /> In order to fully assess the proposed approach of using a volume averaging approach,more <br /> detailed information is required. Please provide the specific methodologies that will be used in <br /> estimating the bulk soil concentration. <br /> Response to General Comment 4: The response indicates that the trespasser youth scenario <br /> will be included as a potential receptor in the conceptual site model. While the revised text has <br /> not been provided to verify this inclusion,the response appears adequate. <br /> RESPONSE TO SPECIFIC COMMENTS <br /> Response to Specific Comment 1 (Section 1.4, paragraph 1.4.2, page 1-2) Summary of <br /> Pertinent Site Data: The response to this comment is adequate, but will need to be confirmed <br /> when the revised figures and text have been submitted for review. <br /> Response to Specific Comment 2 (Section 1.4, paragraph 1.4.2, page 1-2) Summary of <br /> Pertinent Site Data: The response to this comment is partially adequate. The response was <br /> provided in a two-part format. The first part of the response clarifies that the intent of the figure <br /> provided in Appendix C was not to show all 111 Solid Waste Management Units (SWMUs),but <br /> rather was for informational purposes only. This response adequately addresses the first part of <br /> the comment. However, the second part of the response states that"complete characterization or <br /> coverage of the areas under assessment is beyond the scope of this effort..." and,hence, it is <br /> assumed that the figure provided in Appendix C does not comprehensively illustrate all current <br /> sources and locations of contamination. However, the RI/FS Guidance (EPA, 1988) describes <br /> the importance of identifying all locations and sources of site contamination,particularly with <br /> respect to conceptualizing the risks to human health. Hence, identification of all sources and <br /> locations of site contamination should be incorporated in the SAP. <br /> Response to Specific Comment 3 (Section 2.1.2, paragraph 2.1.2.1, page 2-1) Investigation <br /> Scope: The response appears to adequately address the comment. The response indicates that <br /> information pertaining to current and future groundwater use, quality or hydraulic connectively <br /> is beyond the scope of the SAP. As noted in the response to General Comment No. 2, <br /> groundwater contamination and associated risks(i.e.,vapor intrusion)will be addressed under <br /> the OUI remedial action. <br /> Response to Specific Comment 4 (Figure 4,page 2-7)Conceptual Exposure Model: The <br /> response appears to partially address the comment. The response indicates that the percolation <br /> pond retains only clean water and analysis of the sediment in the pond exhibited that all reported <br /> metals were below background levels. However,the conceptual site model indicates that on-site <br /> surface water and sediment are secondary contaminated media. It appears that the intent of this <br /> response is to clarify that surface water/sediment are present in OU2, and as such, they could <br /> possibly be affected by site contaminants through transport pathways such as runoff. While <br /> sampling has been done to demonstrate that sediment are representative of background levels, <br /> 2 <br />