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As indicated on the figure in Appendix C, the area to the east of the Central Area building <br /> contained trichloroethylene(TCE) sites previously addressed under the Record of <br /> Decision. In addition, a TCE groundwater plume is also currently present under this area <br /> and appears to be migrating in an easterly direction. Thus, there may be complete <br /> exposure routes in these areas that are not being addressed. In order to adequately <br /> demonstrate that these areas do not pose any health risks, some additional data in these <br /> areas are required. Please provide the historical data(characterization and/or <br /> confirmation data) that will be used to represent site conditions for the Central Area and <br /> OU-2 in general or revise the sampling analysis plan to include a more comprehensive <br /> sampling approach for OU-2. <br /> 3. The proposed sampling and analysis plan does not include sampling soil for volatile <br /> organic compounds (VOCs), but rather only soil gas samples are proposed for assessing <br /> VOCs. It is noted that the data from the soil gas sampling will be used to assess the <br /> vapor intrusion pathway and subsequent inhalation of VOCs in indoor air using the <br /> Johnson and Ettinger model as modified by the California Environmental Protection <br /> Agency. However, based upon site history information presented in paragraph 1.4.1 <br /> (page 1-2) "industrial degreasing and de-painting operations in each of the geographic <br /> areas released VOCs in to the soil." The plan has not provided soil data to reliably <br /> demonstrate that VOCs are not present in shallow and/or subsurface soil. The sampling <br /> plan does not discuss whether appropriate data to define VOC contamination in soil has <br /> been collected and can be used to support the risk assessment. The lack of VOC data <br /> represents a data gap for addressing potential ambient air exposure and direct contact <br /> with soil. Please clarify how the ingestion of VOCs in shallow and subsurface soil will <br /> be evaluated. In addition, revise the sampling and analysis plan as wan-anted to address <br /> VOCs in shallow and subsurface soil. <br /> 4. The report does not address institutional and/or engineering controls that are in place and <br /> would limit access of the site by a member of the public, i.e., a trespassing youth. Please <br /> discuss why a trespasser youth scenario was not discussed nor identified as a possible <br /> receptor in the conceptual site model (Figure 4). <br /> SPECIFIC COMMENTS <br /> 1. Section 1.4, Summary of Pertinent Site Data, Paragraph 1.4.2, Page 1-2: The report <br /> indicates that a summary table of soil and soil gas samples that have been collected at the <br /> site is provided in Appendix B. However, the data provided in Appendix B only indicate <br /> whether a chemical has been detected at the site and the magnitude and frequency of the <br /> detections. The material provided in Appendix B does not indicate(either in tabular <br /> format or on a figure) the locations of these detections. Therefore, the purpose of the data <br /> provided in the appendix is not apparent. In order for these historical data to be useful, <br /> please revise the report to include a map showing the locations of the detections. In <br /> addition, please clarify whether any of these data provided in Appendix B are to be <br /> included in assessing current site risks. <br /> 2 <br />