SITE INFORMATION AND CORRESPONDENCE

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sampling or data analysis to define vertical extent of OU-1 plume', and investigative efforts which might be required to support the design of OU-1 and any remedial design/remedial action proposed for the SWMUs). Please include a description of the mechanism(s) to be used to perform such work. 4. Site Characterization Report versus Analytical Data Report The distinction and relationship between the Site Characterization Report and the Analytical Data Report are not explained. The Site Characterization Report does not identify the Analytical Data Report in the Introduction. Similarly, the Analytical Data Report does not mention the Site Characterization Report. Further, the Analytical Data Report has no introductory section. • For clarity, the Analytical Data Report should have a brief introduction explaining the purpose of the report and its relationship to the Site Characterization Report. The Introduction of the Site Characterization Report should reference the Analytical Data Report and explain, in very general terms, what types of information can be found in the appendices of the Analytical Data Report versus the appendices of the Site Characterization Report. Sequential numbering of each report volume on the binders would be helpful. 5. Data Quality Objectives (DQOs) The DQO process, as described in recent EPA guidance, is the preferred method for planning and implementing environmental data collection for remedial investigations under CERCLA. The DQO process is a scientifically and legally defensible data collection and planning process to help decide the type, quality and quantity of data sufficient for environmental decision making. It is a process which consists of seven distinct steps. The most recent EPA guidance document on DQOs is "Guidance for Planning for Data Collection in Support of Environmental Decision Making Using the Data Quality Objective Process", Interim Final, October, 1993. The role of DQOs was briefly discussed in the Comprehensive RDFS Work Plan Amendment of June 1993. It is not clear in the SCR Phase I, how DQOs were taken into consideration in the planning and implementation of this Phase 1 RDFS. • Please describe the DQO process that was used during the planning and implementation of this Phase 1 RI/FS and how the DQOs have been addressed. a The subject of vertical extent of contamination in groundwater was commented on by EPA in correspondence dated April 12, 1993, regarding the Comprehensive RDFS Work Plan Amendment. Note that EPA has no written response to EPA's comments (per Section 7.7(e) of the FFA). EPA 14FEE94 2/10