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Executive Summary
On October 11, 2000, near Inez, Kentucky, a breakthrough occurred in
which a 72-acre surface impoundment of waste materials of the Martin
County Coal Corporation released approximately 250 million gallons of
slurry into a nearby underground coal mine. The slurry flowed through the
mine and into nearby creeks and rivers, flooding stream banks to a depth of
5 feet. Although the spill caused no loss of human life, environmental
damage was significant, and local water supplies, taken from the rivers, were
disrupted for days. This incident caused Congress to request the National
Research Council to examine ways to reduce the potential for similar
accidents in the future. To conduct this study, the National Research Council
appointed the Committee on Coal Waste Impoundments. The committee
held a total of 10 meetings between March and July 2001, eight of which
included a town meeting to gain input Mom citizens of local communities.
The charge to the committee includes three major components. First, the
committee was to examine engineering practices and standards currently
being applied to coal waste impoundments and to consider options for
evaluating, improving, and monitoring the bamers that retain coal waste
impoundments. Second, the committee was charged with evaluating the
accuracy of mine maps and exploring ways to improve surveying and map-
ping 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. The committee also
examined alternative disposal options for coal slurry.
It is important to recognize that this charge specifically directs the
committee to focus its analysis on the engineering and characterization of
coal waste impoundments. The committee was not asked to consider other
factors that are related to potential impacts of disposing of coal waste in an
impoundment, or any other disposal option. For example, these factors might
include potential long-term effects on water quality; land-use issues,
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2
COAL WASTEIMPOUNDMENTS
including long-term stewardship of closed impoundments; and economic
and cost-benefit analyses of alternatives. The committee also was not asked
to evaluate the risks of individual impoundments, examine the qualifications
and training of inspectors, or comment on coal mining policy issues not
directly related to impoundments. Although important, such issues are well
beyond the charge to this committee. Furthermore, a comprehensive analysis
of these issues would require considerably more time than was available for
the present study.
Advances in mining technology have increased productivity at the
expense of quality of the run-of-the-mine product, both in terms of included
impurities and a greater proportion of fine-grained coal. This is particularly
true for the coal from eastern coal fields, and upgrading of the product to
meet requirements of power plants and other users is now a common
practice. 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. Coal waste
slurry is usually disposed of by pumping it into an impoundment, where
particles are allowed to settle. Most impoundments in Appalachia utilize the
natural topography to form the storage basin that will contain the slurry. This
is often accomplished by constructing an embankment in a valley or water-
shed to complete the basin structure used for storage. Impoundments are
often located in steeply sloping valleys.
Coal waste slurry facilities have been involved in several accidents since
the 1972 Buffalo Creek incident, where a coal waste impounding structure
collapsed, killing 125 people, injuring 1,100, and leaving more than 4,000
homeless. The majority of the incidents involve failure in the basin area.
Inaccurate mine maps and inadequate characterization of the basin area most
likely contributed to at least some of these incidents. This report, in an effort
to identify potential causes of failure, evaluates current practice in site
characterization, basin placement, and embankment construction, mainten-
ance, and monitoring. It concludes with a discussion of alternative methods
of coal use and waste disposal. Technical terms used in the text are defined
in the glossary (Appendix C).
ENGINEERING STANDARDS,
BARRIER STABILITY AND MONITORING
The Mining Enforcement and Safety Administration developed
standards for impoundments and refuse piles after the 1972 Buffalo Creek
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EXECUTIVE SUMMARY
3
incident. One of the purposes of the Federal Mine Safety and Health Act of
1977 was to establish mandatory standards to protect the health and safety of
miners. This charge is important in assessing the Mine Safety and Health
Administration's (MSHA's) regulatory responsibility and authority associ-
ated with potential impoundment breakthroughs and failures that do not
directly affect the health and safety of miners but may affect persons,
communities, or ecosystems downstream. On the other hand, the Office of
Surface Mining's (OSM's) legislative and regulatory direction under the
Surface Mining Control and Reclamation Act of 1977 (SMRCA) 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. The committee also examined other federal
statutes that may relate to refuse impoun~nents or alternatives (e.g., the
Clean Water Act). The regulatory structure that covers many aspects of the
design, construction, and operation of coal waste impoundments is exten-
sive. The MSHA and OSM regulatory language addresses in detail the
engineering and stability aspects of the embankment; however, there is little
reference either to the basin area or to requirements of the engineering
design for other areas of the facility. The impoundment operator and
professional engineer are responsible for providing information about under-
ground mine workings, including the depth and extent of the workings.
However, no regulation or standard industry practice instructs or guides the
engineer in this task, and there is no procedure for an independent
verification of the information submitted. In addition, there is no regulation
requiring an evaluation of the breakthrough potential of impoundments.
However, in practice, MSHA and OSM appear to have the jurisdiction to
require an evaluation of breakthrough potential through indirect regulatory
language. The committee concludes that while the regulatory review of a
proposed impoundment is detailed with respect to the embankment, the
regulatory review of the impoundment basin has been less rigorous. The
authority for review of the basin characterization and design appears to be
covered only in general language authorizing investigation of all relevant
issues with respect to the impoundment. The committee recommends that
MSHA and OSM should have clear authority to review basin design. It
is not evident to the committee whether specific legislation to authorize
more detailed examination of basin issues is required, or whether these
issues can be handled by additional rulemaking under existing authority.
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4
COAL WASTEIMPOUNDMENTS
The committee examined in particular the elements of design, operation,
and reclamation of coal refuse impoundment systems in the Appalachian
coal region. The principles that govern the design of structures, which were
promulgated in response to the Buffalo Creek disaster, are well understood
and fully documented. An embankment built to contain coal mine waste is
similar to an embanianent built to contain mine waste from other extractive
industries. Reviews of failure modes in other extractive industries are
relevant to identifying potential failure modes of coal waste impoundments.
Given the fact that some modern dams in other extractive industries have
failed, the committee concludes that it is essential that MSHA and OSM stay
current by ensuring that design criteria reflect the latest experience from all
segments of the mining industry. Although the committee has not identified
any deficiencies, it is a matter of due diligence that MSHA and OSM and
industry employ the best available current technology. The committee
recommends that MSHA and OSM continue to adopt and promote the
best available technology and practices with regard to the site evalu-
ation, design, construction, and operation of impoundments. For example,
MSHA and OSM should commission periodic reviews of existing technical
procedures and practices, with particular attention to the basin. Results of the
reviews should be disseminated to industry. Based on the outcome, MSHA
and OSM may need to revise guidelines to establish minimum expectations
and levels of investigation for site characterization, design, construction,
operation, and closure of coal refuse impoundments.
Embankments can fad! in a variety of ways, including slope instability,
liquefaction, and foundation failure. Seepage through embankments can lead
to failure by internal erosion. Overtopping of an embankment can cause
substantial erosion of the crest, which, if left uncontrolled, will work pro-
gressively downward, releasing water and coal refuse downstream. 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. The relative elevations of local drainage and
slurry height, with respect to underground mines, can be a critical design
issue. The stream channel at the base of the impoundment basin defines the
approximate level of local drainage. Coal seams and mines that do not crop
out above the level of the stream channel are termed below-drainage;
whereas, those that crop out along the valley wall above the stream channel
are termed above-drainage. Existing impoundments with above-drainage
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EXECUTIVE SUMMARY
mine workings, where the slurry elevation does not exceed the level of the
coal mine workings, can relatively easily incorporate mitigative measures
for these workings in their design. Above-drainage coal mine workings in
existing impoundments, where the slurry elevation exceeds the level of the
mine workings, are the most challenging in the design and operation of a
facility.
If the outcrop coal barrier is of insufficient width, or the overburden
above the mined area is too thin, impounded water can break into a mine.
Conversely, an inundated mine under high hydraulic head can introduce a
large volume of water into the impoundment. Should a blow-out occur
elsewhere in the watershed, above the pool level, an inflow of substantial
amounts of water into the impoundment can result. This, in turn, may result
in overtopping of the embankment or damage to the principal and emer-
gency spillways. Synergistic reactions among geologic and hydrogeologic
conditions can compound the instabilities created by any one of the failure
modes. Currently, no federal regulations address the width of outcrop barrier
that should be left during underground coal mining. OSM has studied the
problem of outcrop barriers but has released no conclusions to date. The
committee recommends that MSHA and OSM jointly pursue the issue
of outcrop coal barrier width and overburden thickness and its
competence and develop minimum standards for them.
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. The committee recommends that MSHA review its current
practice and develop guidelines for the design of bulkheads intended to
withstand hydraulic heads associated with slurry impoundments. The
bulkhead should be constructed from material that can withstand water
action without deterioration in the presence of the various chemicals in the
impoundment water. Furthermore, the bulkhead should be suitably anchored
in competent, unfractured strata. If such an area is not available, pressure
grouting may be needed. Deterioration of the anchoring strata can be a major
structural problem where the bulkhead is keyed into water-sensitive, clay-
bearing strata. The size, integrity, and s~eng~ of the surrounding coal
pillars, roof, and floor are critical to successful sealing. Generally, seals
constructed for ventilation cannot withstand water pressure.
The committee concludes that selecting the appropriate mitigative
measures relies strongly on reliable basin characterization. The committee
recommends that MSHA and OSM develop and promulgate guidelines
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6
COAL WASTEIMPOUNDMENTS
for the site evaluation, design, construction, and operation of basins.
They should be comparable in scope to the guidelines used in embankment
design.
Monitoring is a critical component in the construction and operation of
coal slurry impoundments. Measurements are commonly made to detect
surface displacements, internal movement, pore pressure, groundwater level,
surface water discharge, and subsurface movement. Procedures in place for
monitoring the embankment, which include visual inspection and instru-
mentation, appear to be performing as envisioned in the regulations MSHA
implemented. For monitoring to be successful, it should be applied to all
potential failure modes. The committee believes that there are opportunities
for additional continuous monitoring that may offer timely warning in case
of impending failure of an embankment or basin. The committee recom-
mends that MSHA and OSM consider requiring additional continuous
monitoring in specific instances and evaluate automation of monitoring
instruments.
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. A particular problem is old surveys and
maps, some of which have been lost or destroyed. If unknown mine workings
are present, the impoundment could suffer unexpected structural failure. In
areas where impoundments are constructed near known or suspected under-
ground mines, vertical and horizontal bamer distances between the mined
area and the impoundment may not be accurate. Current regulations require
closed-loop mine surveys, but surveys for many older mines were not closed.
Furthermore, underground mine surveys may have been based on a foreman's
notes or sketches that lack a reference point or a recognized coordinate
system that would allow accurate location. These shortcomings are more
common in small mines or room-and-pillar mines where a number of short
panels were driven and extracted. Therefore, the committee recommends
that MSHA work with OSM and state agencies to establish standards
for mine surveying and mapping. These should include the following:
=
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EXECUTIVE SUMMARY
.
7
Determining surface coal outcrop locations by aerial topographic
measurements, where adjacent to existing or proposed refuse
impoundments,
· Implementing a coordinated and assertive approach to collecting
and archiving mine maps,
Scanning paper copies of mine maps into electronic data files
upon receipt,
· Setting standards for minimum closure error for all under-
ground closed-loop surveys and that a closed-loop survey be
maintained within a standard distance (to be determined by
MSHA),
· 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 deter-
mining the vertical location of an abandoned mine.
. %,
When no mine maps can be found or there is reason to doubt their
accuracy, additional investigation to locate underground Nine workings is
warranted. This can be expensive and time consuming. Because of the time
and expense and remaining inherent uncertainty associated with extensive
drilling, remote sensing and geophysical methods have been employed to
search for abandoned coal mines. The objective of geophysical surveys is to
determine the physical characteristics of a three-dimensional volume of earth
material, including the presence of voids. Since no geophysical technique is
capable of performing optimally under all geologic and topographic condi-
tions, multiple geophysical techniques may be necessary to reduce the
probability for error to an acceptable level. Drilling is still necessary to
confirm and calibrate interpretations of geophysical and remote sensing data.
The absence of evidence of a mine is not evidence of absence of a mine, and
there are many opportunities for error in the modeling and geophysics
surveys needed to detect voids. The committee concludes that geophysical
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8
COAL WASTEIMPOUNDMENTS
techniques can be useful in coal mine void detection, especially the use of
seismic surface waves, seismic reflection, ground-penetrating radar, and
electrical resistivity methods. The committee also concludes that geophysical
techniques have been underutilized in the coal-mining industry and could
benefit from additional research. The committee recommends that demon-
stration projects using modern geophysical techniques be funded, and
that the results be widely conveyed to the mining industry and to
government regulatory personnel through workshops and continuing
education. Continuing education could include the opportunity to attend
short courses and seminars that present the latest technology along with case
histories to support its use.
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, prepara-
tion, 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. However,
benefits may be difficult to realize because of differences in interests and
perceptions between the mining industry and the utility industry, and
because of the resistance to change embedded in these mature industries.
The committee recommends that the total system of mining, prepara-
tion, transportation, and utilization of coal and the associated environ-
mental and economic issues be studied in a comprehensive manner to
identify the appropriate technologies for each component that will
eliminate or reduce the need for slurry impoundments while optimizing
the performance objectives of the system. The committee concludes that a
similar analysis of the waste use and disposal technologies that malice up the
coal system would have value. The committee recommends incorporating
life-cycle assessment of the costs and environmental impacts of the
alternatives to evaluate them on a more objective, comprehensive basis.
In addition, a detailed analysis of the economic and environmental
impact of the various policy alternatives should be performed.
The opportunities for reducing slurry volume include mining alterna-
tives and coal processing alternatives. However, modern methods of surface
and underground coal mining offer a limited possibility for quality control
during mining. Slurry volume can be reduced by improving fine coal
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EXECUTIVE SUMMARY
9
recovery, minimizing the mass of solids for disposal, and dewatering. Many
dewatering technologies are currently available for specific applications,
though none is likely to be universally applicable. The committee believes
that equipment vendors' current research and development will lead to
improvements in these technologies and that operators of coal waste im-
poundments should monitor them carefully.
Slurry refuse can be used directly for power generation, either in con-
ventional boilers or in advanced combustion and gasification technologies.
Some of these technologies can reduce cleaning requirements for coal.
However, the use of low quality coal feed will increase the amount of waste
generated at the power plant. The committee concludes that technologies for
utilization of fine coal waste for electricity generation in conventional coal-
f~red power plants are available. These technologies offer near-term oppor-
tunities for the reduction of fine coal waste disposed of in impoundments.
However, the coal produced is more expensive than cleaned coal, as a result
of capital and operating costs of additional equipment, and, in the case of
coal water slurry, the additional cost of transportation. To compare tech-
nologies fully, the avoided costs of slurry impoundments must be included
in the analysis.
Fluidized-bed combustion and gasification show promise for recovering
the heat content of fine coal waste while avoiding some of the operational
problems that limit use of coal fines in conventional pulverized coal-fired
boilers. The committee concludes that the burning of fine coal waste in
advanced combustion technologies, such as fluidized-bed combustion and
gasification, is an alternative that shows considerable long-te~m promise.
Atmospheric fluidized-bed units are already in use for combustion of fine
coal waste slurries from both preparation plants and old slurry impound-
ments, 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.
Gasification technologies are also promising for coal water slurries, because
they operate more efficiently, and because emerging technologies can utilize
the water from the slurry as a steam source required for the gasifies. Further
research is needed on the use of fine coal waste slurries as feeds, and
incentives may be useful if these technologies are to be widely incorporated
for fine coal waste combustion. Even though coal combustion wastes from
power plants are already being used for a number of purposes, safe handling
of coal combustion waste from these advanced combustion technologies
should be studied further.
Methods are available for the disposal of coal slurry other than in
impoundments, including both surface and underground options. Alternative
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10
COAL WASTEIMPOUNDMENTS
surface methods include incised ponds, slurry cells, combined refuse piles,
and co-disposal of fine and coarse refuse. In many instances, these methods
are influenced by topography, geology, and mining and coal preparation
characteristics, and, therefore, their application is site specific.
Incised ponds, which are similar to slurry impoundments but without an
embankment, are designed to accept any form of coal waste including slurry.
This method of surface disposal is most common in the Midwest where area
surface mining is practiced on flat topography. Area surface mining produces
long end-cuts and inclines' which are usually allowed to fill with water to
form a permanent lake. These excavations are at or below the level of sur-
face drainage and do not present a danger of sudden failure if used for slurry
disposal.
Slurry cells are designed to impound less than 20 acre-feet of slurry. The
advantage of this method over conventional cross-valley impoundments is
that each cell is small and self-contained and can be designed according to
the strength properties of the coarse refuse. The main disadvantage in steep
terrain is the limited availability of flat land to construct the cells. Another
disadvantage is that slurry cell operations are not compatible with a high
coal preparation production rate.
Combined refuse piles consist of fine refuse from a static thickener that
has been mechanically dewatered and combined with coarse refuse.
Mechanical dewatering to yield the required moisture level is frequently a
problem. In addition, the dewatered material is difficult to handle and
compact. Combined refuse is expensive because of Me high cost of
mechanical dewatering and the potential need for chemical additives to
stabilize the combined refuse. This method is best suited to flat land.
Co-disposal involves the combination of fine refilse from the static
thickener with coarse refuse. This method requires less total storage volume
than separate fine and coarse disposal methods, and the refuse stabilizes
more quickly than typical slurry. Co-disposal has been used primarily in
sparsely populated areas with low annual rainfall. Questions remain about its
suitability for steep hills with high annual rainfall.
If an effective dewatering approach, such as paste thickening, is used,
the resulting waste can be disposed of by thickened high-density residue
stacking. 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. This method is best suited to areas where the slope of the land is
less than 5 percent. The lower throughput rate of deep cone thickeners
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EXECUTIVE SUMMARY
11
compared with that of standard thickeners may significantly affect the
economic feasibility of the method.
For the underground options, two primary methods for injecting fine
coal refuse into underground mines are controlled flushing, where the
underground workings are accessible, and blind or uncontrolled flushing,
where the underground workings have been abandoned or have caved in.
However, several issues are both important and independent of the method
of slurry injection. For example, it is essential to have an adequate supply of
water. This is especially true when water is not being recaptured from the
underground workings. Additional issues include surface ownership, permits,
surface layout, and surface drainage. Filling above-drainage mine workings
with slurry may increase hydraulic head on the coal barriers and result in a
blow-out, making evaluation of mine workings above a surrounding stream
valley critical. The accuracy of mine maps must be ascertained, and the
underground barriers must be assessed for adequacy to contain the slurry.
Mines below the surrounding natural drainage level offer more secure under-
ground disposal sites.
The committee concludes that although there are alternatives to
disposing of coal waste in impoundments, no specific alternative can be
recommended in all cases. Acceptable alternatives are highly dependent
upon regional and site-specific conditions. Also, the alternatives that have
been identified are in varying stages of technological development and
implementation. One of the factors lifting implementation to this point has
been the costs associated with the various alternatives. Additional research is
needed to develop these altematives fiercer and to evaluate the economics of
these processes. The committee recommends that a screening study be
conducted that (1) establishes ranges of costs applicable to alternative
disposal options, (2) identifies best candidates for demonstration of
alternative technologies for coal waste impoundments, and (3) identifies
specific technologies for which research is warranted. Input from MSHA
and OSM regarding regulatory issues will be valuable to such a study. The
committee recommends that the use of economic incentives be explored
as a way of encouraging the development and implementation of alter-
natives to slurry impoundments. The development of incentives should be
based on the full range of the portfolio of technologies as well as the
economics of the technologies. The incentives should be linked directly to
the reduction in slurry production or the utilization of slurry.
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.
However, as processing technologies and the capacity of dewatering
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12
COAL WASTEIMPOUNDMENTS
equipment have improved, the proportion of coal with high energy value
being deposited in slurry impoundments has decreased. In many cases, the
finer slurry materials being disposed of today with less recoverable and
marketable coal are placed over the more amenable, profitable, and recover-
able slurry. Typically, if an impoundment contains at least 1 million tons of
in-situ slurry, a recovery rate of at least 30 percent of a marketable fine coal
product (300,000 tons) from the slurry could prove to be a profitable
venture. 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.
MSHA currently uses two systems to classify coal waste impoundments.
One system classifies impoundments as high, medium, or low hazard, based
upon the magnitude of the potential consequences of failure of the embank-
ment structure. If communities and structures are immediately downstream,
the embankment would be classified as high hazard, regardless of its likeli-
hood to fail. A second system addresses the potential for the unintentional
release of water or SlU~Ty from impoundments into active or abandoned
mines. These ranking systems are based on the proximity of the basin to
underground workings as well as the potential downstream impacts if a basin
were to fail. The second classification comes closer to the standard definition
of risk as the product of hazard (the likelihood of failure) and consequences
(such as loss of life, environmental damage). The committee concludes that
using different hazard classification methodologies for embankments 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 appropriate combination of hazards and
consequences. The committee believes that this can be accomplished using
qualitative risk assessment techniques.
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EXECUTIVE SUMMARY
13
A consistent risk assessment system would allow decisions 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 category and should deter-
mine which mitigation measures should be applied to reduce this risk to
an acceptable level.
The committee also concludes that the design process for impoundments
would be improved by a more formal risk analysis. Proposed new impound-
ments should also be assigned to risk categories, based on a combination of
hazards and consequences, as was suggested for existing impoundments. 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.
The committee believes there is a limit to risk tolerance, for both
existing and new impoundments. When risk is high, and when mitigation,
either through more reliable characterization or barrier construction is
impossible, of limited precedent, or so expensive that it is infeasible, then a
substantial change in operation of the impoundment is warranted. This may
range from minimizing slurry fluidity to ceasing operations. If an
impoundment fails risk-assessment criteria and if risk cannot be mitigated it
should be phased out or alternatives considered.
In collecting information concerning the design of impoundments and
the process by which the design is reviewed by regulatory authorities, the
committee heard reports that the review process is undesirably lengthy,
commonly exceeding 2 years. In addition, it appears that review times have
lengthened considerably in recent years. The committee concludes that
timely review is an essential component of an effective regulatory process.
An efficient and coordinated regulatory review process can be of substantial
benefit to both the applicant and the jurisdictional agencies. A well-
coordinated technical review process can ensure that the health and safety of
both the miners and the public, and the protection of the environment are
ensured in a sensible and streamlined way. Therefore, the committee
recommends that the review process for both new permits and existing
permits be overhauled to include the following elements:
· ~ formal joint process that would coordinate the currently frag-
mented and inefficient collection of reviews into a single
process.
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14
COAL WASTEIMPOUNDMENTS
.
Sufficient staff for engineering and other reviews in the agencies
that participate in the joint process so that the time required to
complete the review can be reduced significantly.
In its review of information about the impacts of uncontrolled releases
of water and slurry from impoundments, the committee found that only very
limited information was available concerning the quantities of trace elements
present in the slurry and associated water. A common theme at the town
meetings was the concern about the quality of ground and surface water.
While a detailed review of the environmental impacts of coal waste
impoundments was beyond the scope of this study, the committee identified
this area as one needing further study. As a result, the committee recom-
mends that research be performed to identify the chemical constituents
contained in the liquid and solid fractions of coal waste, and to charac-
ter~ze the hydrogeologic conditions around impoundments.
Public concern regarding emergency response and evacuation plans was
another recurring theme in public comments made to the committee. Some
residents were unaware of emergency evacuation plans; others had seen
evacuation plans but disagreed with the logic behind the evacuation routes
and would not have used the plan in the event of an emergency. Conversely,
coal industry and regulatory agency representatives stated that these plans
are being developed and shared with the public through the various
community contacts (e.g., local fire departments, police, health care pro-
viders). 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. The committee concludes
that communication concerning coal refuse impoundment risk and emer-
gency response between the industry and the local communities could be
improved substantially. The committee suggests that the industry take steps
through the appropriate emergency response agencies to address these
problems.
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 future impoundments, ways to
improve the assessment and mitigation of risks associated with impound-
=
OCR for page 15
EXECUTIVE SUMMARY
15
meets, and 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 impound-
ments, particularly through the mechanism of breakthrough into nearby
underground mine workings. 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. With the recommended improvements in each of
these areas, the potential for incidents like that in October 2000 at Inez,
Kentucky, can be reduced.
1
OCR for page 16
16
COAL WASTE IMPOUNDMENTS
Some residents were unaware of emergency evacuation plans; others had
seen evacuation plans but disagreed with the logic behind the evacuation
routes and would not have used the plan in the event of an emergency.
Conversely, coal industry and regulatory agency representatives stated that
these plans are being developed and shared with the public through the
various community contacts (e.g., local fire departments, police, health
care providers). The lack of realistic communication constitutes a funcia-
mental 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. The committee concludes
that communication concerning coal refuse impoundment risk and emer-
gency response between the industry and the local communities could be
improved substantially. The committee suggests that the industry take
steps through the appropriate emergency response agencies to address
these problems.
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. 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, ant! operation in addition to appropriate monitoring. With the
recommended improvements in each of these areas, the potential for
incidents like that in October, 2000 at Inez, Kentucky, can be reduced.
Prepublication Version - Subject to Further Editorial Correction
Representative terms from entire chapter:
fine coal
