SITE INFORMATION AND CORRESPONDENCE

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SWMU 8, or further justification provided as to how the revised remedy is protective of human health and the environment, given the level of uncertainty at SWMU 8. SPECIFIC COMMENTS 1. Section 2.2.1, Page 2-1: The text presents three bullets that explain the basis for changes and clarifications needed for the LUCs. However, it is unclear why SWMU 8 and DSERTS 67 are not discussed here. Please provide an explanation why these two sites are not included in the discussion, or add them to the text. 2. Section 2.3.0.2,Page 2-1: The text states that LUCs are required for contaminated soil left in place, but does not include SWMU 8 in the list of sites. Please add SWMU 8 to the discussion since uncharacterized contamination remains at the site. 3. Section 3.3.2,Page 3-7: The following statements indicate that the DLA proposes to alter the soil cleanup standards for 2,4,5-T and Lindane at SWMU 6 as follows: "Based on the DI-WET result, the cleanup standard for 2,4,5-T is revised from 5 ug/kg to 13 ug/kg. The results from SESOIL and VLEACH modeling that indicate concentrations reaching groundwater would not exceed beneficial use limits support revision of the cleanup standard for Lindane from 1.7 ug/kg to 5 ug/kg." To support these revisions, more information needs to be included in this section. This information includes the following: (1) an indication if these revised cleanup standards will alter any of the land use controls for this site, (2) a more detailed discussion of how the DI-WET result was used(including supporting calculations) to justify raising the cleanup standard for 2,4,5- T, (3) a more detailed discussion of how the VLEACH modeling results were used to justify raising the cleanup standard for Lindane, (4) a discussion of the pros and cons of using different rationale (DI-WET vs modeling)to raise the cleanup standard depending on the compound being evaluated and (5) a detailed discussion of the uncertainties in the information provided. Also, there are two sections numbered"3.3.2". The second section should be Section 3.3.3., or the two combined. In the second Section 3.3.2,please include an explanation of the basis for and the threat to human health and the environment from raising the cleanup standards for 2,4,5-T and Lindane. 4. Section 4.0,SWMU 8: This section proposes changes to the originally proposed remedy that need additional supporting information and rationale, including raising the DDT cleanup standard for soil from 7 ug/kg to 103 ug/kg and raising the Dieldrin cleanup standard from 2 ug/kg to 5 ug/kg. Similar to the comment on SWMU 6, the proposal to raise the cleanup standards for DDT and Dieldrin needs to include supporting calculations for the DI-WET results, more detailed rationale for the proposed changes, and an uncertainty discussion. 2