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Mr. Robert Doss <br /> June 20, 1997 <br /> Page 3 <br /> 7. As discussed in Section 7.2 <br /> groundwater inSectio , Alternative I includes a contingency try <br /> monitoring plan if groundwater plume ex triggered by the <br /> goal of this contingency would be to provide control of thePlumed preconfirmevent he <br /> further expansion. Alternatives which include groundwater extraction have been <br /> evaluated in the FS and have been determined to be effective for providing control <br /> of the plume and therefore should be proposed in recommendations presented in <br /> Section 9.2. At a minimum, the recommended contingency alternative must <br /> Provide capture of the plume and support atttainment of cleanup objectives. <br /> 8• Section 6.1.1.3 is misleading because it states that removal <br /> area polygons would achieve the established goals. of only non-source <br /> This Section implies, but does <br /> not state, that source area residues would also need to be removed to achieve the <br /> goals. <br /> 9 The goal for the source area soil option presented on Figure 6-9 includes only"ND <br /> at Perimeter/MCL under" therefore appears to be incomplete. <br /> 10. Retained soil remedial options shown on Figure 6-13 do not correspond to the <br /> description presented in Section 6.1.3. Off-site asphalt batching is not depicted as <br /> a residue technology option, and on-site thermal desorption is not depicted as a <br /> Non-Source Area technology option. <br /> 11. To eliminate confusion, the terms scenarios, technologies, options, and alternatives <br /> should not be used interchangeably in the FS. The terms "technologies" and <br /> "options"had been presented as components of alternatives in Chapters I-5 and <br /> then used interchangeably in Section 6 and 7. For example, Section 6.2 presents <br /> "options"A 1 through A7 and C 1 through C4 for groundwater, these same options <br /> are referred to as"alternatives" in Section 6.2.3.1, Section 6.2.3.2, and Figure 6- <br /> 30, then referred to as options again in sections 6.2.3.3 and then referred to as <br /> alternatives on Table 7.1. Section 7.2 follows with the development of"Remedial <br /> Action Altematives". <br /> 12. Section 6.2.3.2 discusses that Alternative A2, "ORC for enhancement of <br /> biodegradation", would be difficult to implement due to the large number of wells <br /> (thirty 80-foot deep wells) required. The basis for the required number of wells <br /> should be presented to support this conclusion. <br /> 13. The title of Table 9-1 should be changed to reflect the purpose of Section 9. <br /> Detailed analyses of alternatives were presented in previous chapters. Section 9 <br /> presents the conclusions and recommendations resulting from the FS and does not <br /> present a"detailed analysis" of final remedial alternatives. As discussed in <br /> comment #5 above, all remaining alternatives must be presented in detail. <br /> Alternatives presented in Table 9.1 and/or the subsequent section inadvertently left <br /> FA.UW <br /> ,g-Me <br />