Conclusions and Recommendations - Coal Waste Impoundments: Risks, Responses, and Alternatives - page 155

should be linked directly to the reduction in slurry production of the utilization
of slurry.
One way to reduce the volume of material in older slurry impoundments is
to recover or remine the fine coal. Profitable remining may be possible if
impoundments contain at least 1 million tons of in-situ slurry material, at an
expected recovery rate of a marketable fine coal product of not less than 30
percent. 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 of fuel.
ADDITIONAL RECOMMENDATIONS
In its deliberations, the committee identified several issues that cut across
the elements of the statement of task. In addition, related areas warrant
additional study, in the committee's view.
The committee notes that MSHA uses two systems to classify coal waste
impoundments. One system classifies impoundments as high, medium, or low
hazard, based on the magnitude of the potential consequences of a failure of the
embankment structure—an embankment where people live and structures have
been built immediately downstream would be classified as high hazard,
regardless of the likelihood of failure of the embankment. A second system,
which deals with basin failures, includes assessments of the proximity of
underground mine workings, the potential for failure that would release slurry
or water into those workings, and the potential impacts of a release. The second
classification system comes closer to the standard definition of risk. Using
different methodologies for classifying embankment and basins is
inappropriate. Therefore, the committee recommends that: (1) MSHA and
OSM review activities related to risk assessment for existing
impoundments (including both embankments and basins) to ensure that
they are consistent and that they distinguish appropriately between hazard
and consequence assessment in the methodologies adopted; and (2) MSHA
and OSM establish a single, consistent system, which should be used to
assign both embankments and basins to risk categories. The ranking should
be based on the combination of hazards and consequences, such as loss of life,
cost, and environmental impact. This can be accomplished using qualitative risk
assessment techniques.
A consistent risk assessment system would allow decisions on
impoundments to be based on their relative risks. The committee recommends
that MSHA and OSM oversee a thorough assessment of potential
mitigation measures for those impoundments that fall in the highest risk