SITE INFORMATION AND CORRESPONDENCE

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Frank Dellechai• • Page 5 January 24 , 1989 material, unless a large mound of hazardous waste is created. Hargis should study this concept of transferring wastes from Pond 2 to Pond 1 more closely. (C) . There was no rationale given why the top three inches of soil were to be stabilized. Why not the top six inches, or some other specific measure? The contractors were asked to review that part of the Closure Plan and either continue with the three-inch figure or propose a new figure. They were asked to provide the rationale behind their choice. Another major problem with the Closure Plan is that while it addresses closure of Pond 1 and Pond 2 , it does not adequately address the closure of 'the 1, 1,1-Trichloroathare Disposal area adjacent to Pond 2 , and the boundaries of the area to be capped. The boundaries of the area to be capped have not been identified. In conjunction with this, there is no drawing of the cap of the area to be closed. The contractors need to identify these boundaries and provide appropriate rationale. The contractors were asked to address closure of the TCA disposal area and provide a drawing showing the boundaries of the proposed cap. A third major problem with the Closure Plan is that it does not adequately address the possible discharge area from the laboratory sink. The Closure Plan says that this "will be further investigated during closure of the impoundments, per HSWA requirements. " The contractor should make an attempt to identify and quantify these wastes and associated discharge areas in the Closure Plan. Another major problem with the Closure Plan, and perhaps the most important one, is that the plan did not address the Title 22 requirement that a liquid monitoring and collection system should be incorporated into the sand/aggregate layer between the asphalt and synthetic membrane cap. Preliminary drawings and plans, and eventually as-built drawings, for the cap and drainage control facilities need to be submitted. A fifth problem with the Closure Plan is the Cost Estimate for closure. This part of the plan should be looked at. The contractors asked if DHS thought the estimated costs were high or low. DHS said it did not know £or sure, but that the estimated costs might be on the low side when considering the deficiencies of the Closure Plan and their required corrections. The contractors asked DHS if they could consider alternatives when submitting their revised Closure Plan, such as removing the sludge and contaminated soil from the site and going with a clean closure. DHS said they should explore any and all alternatives.