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Executive Summary
Pages 1-16

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From page 1...
... Second, the committee was charged with evaluating the accuracy of mine maps and exploring ways to improve surveying and mapping of underground mines to delineate more accurately how underground mines relate to current or planned slurry impoundments. The third task was to evaluate alternative technologies that could reduce the amount of coal waste generated or allow productive use of the waste.
From page 2...
... The treatment of the raw coal can produce as much as 50 percent waste as coarse included rock and as fine-grained coal and mineral matter. Coal waste slurry is one of the refuse streams and is composed mainly of fine coal, small particles of rock, and clay suspended in water.
From page 3...
... to protect society and the environment from the adverse effects of surface coal mining operations, complements the intent of the Federal Mine Safety and Health Act. The committee examined the regulations by MSHA and OSM and its state delegate programs that directly relate to the design, construction, operation, and closure of refuse impoundments, as well as to alternative refuse disposal techniques.
From page 4...
... While continued vigilance concerning design, construction, and operation of embankments is clearly warranted, the committee concludes that the largest uncertainties remain in the characterization of the basin area and, therefore, in the mitigation of risks associated with the breakthrough potential. The potential for underground coal mine workings to be near an impoun~nent is a factor in the design of new and in modifications to existing coal waste impoundments in Appalachia.
From page 5...
... If slurry Tom an impoundment leaks into active or abandoned mine workings or may do so, bulkheads or seals may be constructed to preclude the water from escaping into the outside environment. Many mitigative measures can be designed using established procedures; however, bulkheads designed to support high hydrostatic pressure present a different kind of problem.
From page 6...
... SITE CHARACTERIZATION Key to assessing the potential for breakthrough of coal slurry into underground mine workings is knowing the extent of those workings with respect to the ground surface in the impoundment basin area. The committee examined several aspects of the topic of site characterization, including geology, hydrogeology, the accuracy of surface and mine maps, and methods for delineating the extent of underground mine workings in situations where maps are nonexistent or inaccurate.
From page 7...
... , · Recording the depth of the last cut taken to a level of accuracy to be determined by MSHA, Using state plane coordinates or latitude and longitude, and bottom-of-seam elevations as the map base reference, Listing appropriate coordinate transformation eauation(s) on the mine map, Adding a qualifying statement to accompany any coordinate transformation that is based upon the alignment of surface features, Improving and maintaining the location of surface controls, Determining which mine permit documents should be retained, in what form, and for how long, Avoiding the use of coal seam names as the sole basis for determining the vertical location of an abandoned mine.
From page 8...
... ALTERNATIVE TECHNOLOGIES Coal waste impoundments are one of the waste disposal options of the present system of mining and preparing coal for energy production. To assess thoroughly other alternatives, the entire system of mining, preparation, refuse disposal, transportation, and power generation should be explored through an in-depth life-cycle assessment, including cost assessment, with the goal of optimizing the system to generate less fine coal waste while maintaining the performance and economics of the system.
From page 9...
... Atmospheric fluidized-bed units are already in use for combustion of fine coal waste slurries from both preparation plants and old slurry impoundments, but they have not gained wide usage. Pressurized fluidized-bed technologies offer improved efficiency over atmospheric technologies but have not been utilized in full-scale applications for burning fine coal waste.
From page 10...
... Although used in other extractive industries, this process has seen limited use in the coal industry for the disposal of fine coal refuse. Three considerations land availability, steep terrain, and cost hamper applying unsupported thickened high-density residue stacking to fine coal refuse disposal.
From page 11...
... One method for reducing the volume of material in older slurry impoundments is to recover or remine the fine coal. Older impoundments contain significant amounts of coal refuse with recoverable energy value.
From page 12...
... The committee concludes that as advances are made in the use of low value coal or coal water slurry, remining of slurry impoundments can be an attractive source for fuel supply. ADDITIONAL RECOMMENDATIONS In its deliberations, the committee identified several issues that cut across elements of the statement of task and some related issues that warrant additional study.
From page 13...
... To maximize the potential for risk reduction, the committee recommends that all impoundment designs be accompanied by a risk analysis utilizing qualitative methods. Examples of such methods include Potential Problem Analysis and Failure Modes and Effects Analysis.
From page 14...
... . The lack of realistic communication constitutes a fundamental barrier to the industry's ability to make stakeholders aware of the risk associated with coal refuse impoundment construction, operation, and closure and of steps taken to mitigate that risk.
From page 15...
... In addition, the committee believes that viewing the designs of embankment and basins as well as the entire process of handling and burning coal as systems of interlinked components that operate together is an appropriate way to balance alternatives for creating, handling, and disposing of wastes and to understand and mitigate the impacts of failure of any element in these systems. The safe operation of these systems is a shared responsibility of government and industry that depends on effective engineering design, construction, and operation in addition to appropriate monitoring.
From page 16...
... SUMMARY The conclusions and recommendations offered above reflect the committee's judgments concerning ways to improve the design process for coal waste impoundments, ways to improve mapping of mines and the characterization of sites of existing and fixture impoundments, ways to improve the assessment and mitigation of risks associated with impoundments, anal ways to assess options for coal waste slurry. The committee believes that implementation of the recommendations will substantially reduce the potential for uncontrolled release of coal slurry from impoundments, particularly through the mechanism of breakthrough into nearby underground mine workings.


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