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-8- 3. The application observes, on page 21 and 22 of appendix 3.3-3a, that collapsible soils have been determined to exist within the impoundment site. Further, the application observes that pre-wetting or soil removal and recompaction may be necessary to remedy this construction problem. The applicant should elaborate upon detection and treatment techniques to be used, in order to preclude development of hydrocampactible soil problems. 4. The application observes, on page 24 of appendix 3.3-3a; "...sizing of the required blanket drain and drain collection system be performed after an appropriate borrow sources is located and size gradation of refuse are determined. The final plans and specifications should have sufficient flexibility to allow modifications during construction to account for the changes in the engineering characteristics of the coal refuse. It should be recognized that only through inspection and monitoring of the embankment, can proper design modifications or changes in construction methods be made." The applicant should detail the drain hydraulic and mechanical design parameters which will be attained in completing construction. Further, the application should detail the construction inspection and monitoring program which will be utilized during construction of the embankment. 5. The application contains monitoring recommendations for embankment seepage and movement. On pages 25-27 of appendix 3.3-3a, recommendations are made for monitoring of embankment seepage, phreatic surface levels within the embankment, pore water pressures, and movement of the structure. The Division concurs all of these recommendations. The application will need to be amended to detail specific type and location of monitoring installations, as well as the frequency of observations and reports to be completed. 6. On page 27 of appendix 3.3-3a, the final page of the design report text, the consultant recommends; ..the engineering characteristics of the coal refuse be evaluated once sufficient quantities of refuse are available." Approval of the embankment design will require the inclusion of a stipulation conditioned upon the submission of test results to properly verify the report's mechanical material assumptions. Failing verification of the engineering characteristics assumed in completing the original design, immediate redesign will be required. 7. The Division has requested that the US Bureau of Mines Denver Technical Center complete a review of the proposed embankment design. If their staff review determines any design inadequacies, appropriate supplement comments will be forwarded to the applicant. Reclamation Plan -Rules 2.05.4, 4.13, 4.14 and 4.15 1. The applicant needs to provide more detailed cost estimates for the worst case situation of reclamation during the proposed 5 year permit term. These costs estimates should include volumes of material to be removed and replaced, equipment proposed to be used, supporting assumptions and calculations, and citations for references used.