EPA-600/2-78-068
April 1978
Environmental Protection Technology Series
ACID MINE DRAINAGE AND SUBSIDENCE:
Effects of Increased Coal Utilization
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-78-068
April 1978
ACID MINE DRAINAGE AND SUBSIDENCE:
EFFECTS OF INCREASED COAL UTILIZATION
Ronald D. Hill and Edward R. Bates
Resource Extraction and Handling Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 1*5268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 1*5268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental Research
Laboratory, U. S. Environmental Protection Agency, and approved for
publication. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
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FOREWORD
When energy and material resources are extracted, processed, converted,
and used, the related pollutional impacts on our environment and even on our
health often require that new and increasingly more efficient pollution control
methods be used. The Industrial Environmental Research Laboratory-Cincinnati
(lERL-Ci) assists in developing and demonstrating new and improved methodol-
ogies that will meet these needs both efficiently and economically.
The Committee on Health and Ecological Effects of Increased Coal
Utilization requested from the Environmental Protection Agency several status
reports describing environmental impacts of increased coal production. The
Industrial Environmental Research Laboratory-Cincinnati was requested to
prepare a paper discussing the impact of acid mine drainage and subsidence.
This report is that effort. In total, eleven papers were produced for the
Committee, which reviewed the issues and prepared a report of their findings
to the President. Further information on the Committee report can be obtained
from Dr. David Rail, Chairman, Committee on Health and Ecological Effects of
Increased Coal Utilization, National Institute of Environmental Health
Sciences, Research Triangle Park, Forth Carolina 27709.
For further information on the report contact the Resource Extraction and
Handling Division.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
in
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ABSTRACT
The increases above 1975 levels for acid mine drainage and subsidence for
the years 1985 and 2000 based on projections of current mining trends and the
National Energy Plan are presented. No increases are projected for acid mine
drainage from surface mines or waste since enforcement under present laws should
control this problem. The increase in acid mine drainage from underground mines
is projected to be 16 percent by 1985 and 10 percent by 2000. The smaller
increase in 2000 over 1985 reflects the impact of the PL 95-8? abandoned mine
program. Mine subsidence is projected to increase by 3*t and 115 percent
respectively for 1985 and 2000. This estimate assumes that subsidence will
parallel the rate of underground coal production and that no new subsidence
control measures are adopted to mitigate subsidence occurrence.
IV
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CONTENTS
Foreword . iii
Abstract iv
Figures vi
Tables vii
I Executive Summary * 1
II Acid Mine Drainage 5
III Subsidence 17
TV References. . 27
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FIGURES
Number Page
1 Geological and Mining Conditions Related to Underground
Roof Failures and Resulting Surface Subsidence ...... 19
2 Factors Affecting the Amount and Rate of Surface
Subsidence 20
VI
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TABLES
Number
1 Estimated Increase in Acid Mine Drainage and Subsidence
for the Years 1985 and 2000 Expressed as Percent
Increase Above 1975 Level ................. 3
2 Typical Acid Mine Drainage ...... . ........... 5
3 Acidity Figures for Appalachian Area Coal Mines ....... 6
U Distribution of Acid Mine Drainage Problems in Coal
Producing States ...................... 7
5 Effluent Limitations, in Milligrams per Liter Except
for pH ........................... 9
6 Annual Production of Coal in lO BTU ............ 15
•»
7 Sulfate Releases Associated vith Eastern Underground
Mining ........................... 16
8 Increase of Acid Mine Drainage over 1975 Levels (Percent) . . 16
9 Surface Subsidence Classification and Morphological
Characteristics ...................... 21
10 Annual Temporary Land Use Associated with Eastern
Underground Mining ..................... 26
11 Annual Production of Coal in 10 ^ BTU from Underground
Coal Mines ......................... 26
VI1
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SECTION 1
EXECUTIVE SUMMARY
ACID MINE DRAINAGE
One of the most damaging waterborne contaminants from coal mining opera-
tions is the acid generated from the exposure of iron sulfide minerals found in
some coal and overburden. Not only does the acid directly impact stream biota,
eat away metal structures and destroy concrete, but as a result of the low pH,
other ions such as heavy metals, become solubilized and carried into water
courses. These ions are often toxic to aquatic life and render the water un-
usable for domestic and industrial use. In 1969, it was estimated that in
excess of 10,000 miles of streams had been degraded by acid mine drainage.
Water pollution control legislation and regulations, adopted by both federal
and state governments since the initial survey was made, have resulted in a
significant improvement in water quality where active mines are operating.
Mine operators are treating acid mine drainage emanating from active mines in
compliance with legal requirements. But because active and abandoned mines
are located, in some instances, adjacent to each other, or discharge into the
same stream, the overall improvement in water quality in those areas has not
been as significant. The amount, and rate of acid formation, and the quality
of water discharged are a function of the amount and type of pyrite in the
overburden rock and coal, time of exposure, characteristics of the overburden,
and the amount of available water.
Acid mine drainage is a unique pollutant, because acid generation and
discharges continue to occur after mining has ceased. Underground mines con-
tribute over TO percent of the acid mine drainage. Inactive mines contribute
a significant amount. The acid mine drainage problem is essentially a regional
one. Most of the problem lies in the Appalachian Region (Federal Regions 3,
k, and 5)5 but acid discharges are found in the Interior Region in the states
of Indiana, Illinois and Western Kentucky. Except for some isolated situations,
acid mine drainage is not a problem in the western states.
Of the 21 coal producing states, all but two have some form of a law to
control environmental damages from surface mining. The degree of control
afforded by these laws and regulations vary drastically from state to state.
However, the passage of the Surface Mining Control and Reclamation Act of 1977)
PL 95-87j on August 3, 1977» will result in federal environmental standards for
the the extraction of coal from surface mines and also set standards for the
surface effects of underground mining. These regulations will go into effect
in February 1978. Many of the provisions of the Act and the subsequent regula-
tions will result in the control and reduction of acid mine drainage. State
and federal laws for the control of acid discharges from inactive underground
and surface mines have not been enacted. However, PL 95-87 establishes an
abandoned mine reclamation fund and program, which should reduce the backlog
of acid mine drainage producing situations.
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SUBSIDENCE
The mining of a substantial quantity of underground material such as coal
creates a void which in turn often produces a condition of instability within
the rock leading to collapse of the overlying rock into the void and frequently
associated surface subsidence. The condition may occur during the conduct of
the mining operation or may not occur until many years after mining has been
completed as the pillars slowly decay to the critical failure point.
Earth movements at the surface may result in many varied types of damage.
Buildings are more severely affected by the compressive and extensive strains
associated with subsidence than they are by the actual settlement. Highways,
bridges, water and gas lines may be sheared, twisted or broken by strains and
slope changes produced by subsidence. Sewage lines are especially susceptible
to changes of slope that locally reverse their direction of flow. Effects
upon the natural environment can also be quite dramatic. Natural drainage
patterns can be changed resulting in formation or occasional destruction of
swamps. Surface streams often are intercepted by subsided areas or induced
rock fractures resulting in flow into deep mines and loss of surface waters.
In severe cases groundwater supplies may be intercepted and drained into under-
lying deep mines. No definitive national analysis of the amount of land affected
by past mine subsidence or of the annual or total property damage has been made.
Although methods exist to permit mining of a portion of the coal under
developed areas without inducing subsidence, it is not likely that mine opera-
tors will voluntarily abandon a large percentage of their mineral resource
unless they are required to provide surface support. If the mine operator must
provide surface support then approximately 50 percent of the mineral must be
abandoned which raises a key policy issue in terms of meeting the Nation's
energy needs.
If no actions are taken by the Federal or State governments to control
subsidence problems from future mining, then it is likely that present problems
will be compounded and eventually remedial action will become necessary by
government agencies. Only one state, Pennsylvania, has enacted legislation
specifying the separate responsibilities of surface owners and mine operators
for subsidence damage.
Projections
Table 1 provides estimates of the increases above 1975 levels for acid
mine drainage and subsidence for the years 1985 and 2000 based on projections
of current mining trends and the National Energy Plan. No increases are pro-
jected for acid mine drainage from surface mines or mine waste since enforce-
ment under present laws should control this problem. The increases in acid
mine drainage from underground mines and increases in mine subsidence will be
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felt principally in Regions 3, b, and 5 with negligible increases expected in
other regions. The smaller increase in acid mine drainage in 2000 over 1985
reflects the impact of the PL 95-8? abandoned mine program.
TABLE 1. ESTIMATED INCREASE IN ACID MINE DRAINAGE AND SUBSIDENCE
FOR THE YEARS 1985 and 2000 EXPRESSED AS PERCENT INCREASE ABOVE 1975 LEVEL
Acid Mine Drainage Subsidence
1985 2000 1985 2000
Surface Mines . . . .
Pre-NEP 0}a{ 0)aJ
NEP 0(a' 0(a'
Mine Waste . / >
Pre-NEP 0(a' 0^a'
NEP 0 0
Underground Mines , , , N , , / N
Pre-NEP 16 ? 10
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surface subsidence "by controlling the mining operation to minimize surface
disturbance. For nondeveloped areas the emphasis must "be placed upon delaying
surface development until the coal resource is extracted and the area has
undergone subsidence and stabilized.
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SECTION 2
ACID MINE DRAINAGE
CAUSE OF ACID MINE DRAINAGE
One of the most damaging waterborne contaminants from coal mining
operations is the acid generated from the exposure of iron sulfide minerals
found in the coal and overburden. Not only does the acid directly impact
stream biota, eat away metal structures and destroy concrete, "but as a result
of the low pH, other ions such as heavy metals, become solubilized and
carried into water courses. These ions are often toxic to aquatic life and
render the water unusable for domestic and industrial use. In 196*9 ** was
estimated that in excess of 10,000 miles of streams have been degraded by acid
mine drainage^'. This figure is surely less today as a result of treatment
of acid mine drainage from active mines by industry and improved surface
mining techniques.
The removal of overburden often exposes rock materials containing pyrite
(iron disulfide). The oxidation of pyrite (FeS2) results in the production
of ferrous iron and sulfuric acid. A further reaction then proceeds to form
ferric hydroxide and more acid. As noted in Table 2, the products of these
various reactions are iron, sulfate, acid and the various heavy metals that
may be associated with the host pyrite such as Cu, Zn, Al, and Mn.
TABLE 2 - TYPICAL ACID MINE DRAINAGE^
Parameter(a) Mine #\ Mine #2 Parameter^a^ Mine #1
pH 5.0 2.8 As 0.01
Acidity, CaC03 6^0 U?0 B 0.5
Alkalinity, CaCOo 17 0 Cd <0.001
Ca, CaC03 370 210 Cr 0.05
Mg, CaC03 110 93 Hg 0.0003
Fe, Total 300 93 Cu 0.01
Fe, Ferrous 270 -0 Ni 0.20
Na WO 2 Se <0.001
Al 15 31 Zn 0.25
Mn 6 it POjj 8.6
SOr 301*0 610
T.D.S. U320 1050
Conductivity 376"0 1190
(a) All units mg/1 except pH and conductivity (micromhos/cm).
(b) In-house EPA data.
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The amount, and rate of acid formation, and the quality of water dis-
charged are a function of the amount and type of pyrite in the overburden rock,
and coal, time of exposure, characteristics of the overburden, and amount of
available water. Crystalline forms of pyritic material are less subject to
weathering and oxidation than amorphic forms. Since oxidation is the primary
reaction during early acid formation, the less time pyritic material is exposed
to air, the less acid is formed. It has also been observe'd that even under
ideal physical and chemical conditions for oxidation that the reactions do not
proceed at their maximum rate immediately. If the overburden also contains
alkaline material such as limestone, acid water may not be discharged even
though it is formed, because of inplace neutralization by the alkaline material.
Discharges from this situation are usually high in sulfate.
Enough water to satisfy the pyrite oxidation reaction is usually available
in the overburden and coal material. Water also serves as the transport
medium that removes oxidation products from the mining site into streams.
Control of this water is a positive pollution preventative method.
Bacteria are almost always present in acid mine drainage. These bacteria
obtain their energy for growth from the oxidation of reduced sulfur compounds
and ferrous iron. Their role in pyrite oxidation is still under debate. They
plan a significant role in the oxidation of ferrous iron to the ferric form.
From an acid mine drainage control standpoint, the role of the bacteria is un-
important because l) iron oxidizing bacteria are common in soils, etc. and
thus the source cannot be controlled, 2) bactericides have not been shown to
be effective, and 3) oxygen control impedes the reaction whether it is chemical
or biological.
Acid mine drainage is a unique pollutant, because acid generation and
discharges continue to occur after mining has ceased. The most comprehensive
survey of the magnitude of acid mine drainage discharged was reported in .\969-
The results of this survey are shown in Table 3.
TABLE 3 - ACIDITY FIGURES FOR APPALACHIAN AREA COAL MINES
(1)
Acidity
Source 1,000 Ib/day Percent
Underground, Active 6lk 19
Underground, Inactive 1,712 53
Surface, Active 28 01
Surface, Inactive 361 11
Combined, Active* 60 02
Combined, Inactive* 238 07
Other 2k5 07
3,258 Too"
*Includes sources where underground could not be separated from surface.
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As noted here tinder ground mines contribute over TO percent of the
acid mine drainage. Inactive mines are also a major contributor.
The acid mine drainage problem is essentially a regional one. Most of
the problem lies in the Appalachian Region (Table k). Acid discharges are
found in the Interior Region in the states of Indiana, Illinois and Western
Kentucky. Except for some isolated situations, acid mine drainage is not a
problem in the western states, because the coal and overburden have a low
pyrite content and a high alkaline content.
TABLE U - DISTRIBUTION OF ACID MINE DRAINAGE PROBLEMS IN COAL PRODUCING STATES
Federal Acid Mine Federal Acid Mine
State Region Drainage State Region Drainage
Alabama k yes New Mexico 6 no
Arizona 9 no North Dakota 8 no
Arkansas 6 no Ohio 5 yes
Colorado 8 no'a' Oklahoma 6 no
Illinois 5 yes^' Pennsylvania 3 yes
Indiana 5 yes Tennessee U yes
Iowa 7 no\a> Texas 6 no
Kansas 7 no Utah 8 no
Kentucky U yesv"b) Virginia 3 no
Maryland 3 yes Washington 10 no
Missouri 7 no}a> West Virginia 3 yes
Montana 8 no(a' Wyoming 8 no
(a) Isolated cases of acid mine drainage have been reported.
(b) Large portions of coal fields do not have acid mine drainage problems.
EFFECTS OF ACID MINE DRAINAGE
The quantification of the impact of acid mine drainage in terms of
dollars loss has never satisfactorily been accomplished. The major impacts
are:
1. Aquatic life is destroyed and productivity reduced.
2. Water-based recreation is reduced.
3. Deleterious effects on industrial water users are incurred,
manifested by high acidity, hardness, iron and manganese.
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U. Municipal water supplies are impacted by acidity, iron, hardness,
dissolved solids and manganese.
5. Highway and navigation facilities are impacted "by increased
corrosion of metal structures.
The Applachian Regional Commission study reported that in excess of
10,000 miles of streams have been degraded with acid mine drainage'-^. The
majority has occurred in the Appalachian region. This figure undoubtedly is
less today as a result of the treatment of mine drainage at active mines.
CONTROL OF ACID MINE DRAINAGE
Mines can be divided into two categories: surface and underground.
Surface mines can further be divided into three basic types: (l) area mines,
located on relatively flat land, usually less than 200 feet deep and covering
large areas, (2) contour mines, found in mountain areas, usually less than
150 feet deep, narrow and long, and (3) pit mines, usually deep, often having
a high coal-to-overburden ratio.
Treatment
Technology is available to neutralize the acid mine drainage discharged
from mines'2). The effluent guidelines established by EPA are based on the
neutralization of acid mine drainage to meet the standards shown in Table 5-
Although the water treated in this manner will have a satisfactory pH, acidity,
iron and manganese for most uses, the water will still have a high hardness
and dissolved solids content making it unsuitable for some uses. Except for a
few situations, treatment is not considered a viable solution for inactive
mines because of the long treatment period required, high costs and the unavail-
ability of a responsible party. Reverse osmosis and ion exchange methods are
available to treat acid mine drainage and produce a near potable water, but due
to their high cost, they would only be used in special cases. Treatment is the
usual control method employed at underground mines during active mining and in
conjunction with preventative methods during active surface mining.
Underground Mines
Since acid formation has been found to be a result of the oxidation of
pyrite, all acid mine drainage preventative technology is based on the reduc-
tion or elimination of the exposure of pyrite to air. Water serves as a
transport media and a reactant in the oxidation process. Water control methods
attack the transport phases and not the reactant phase, since sufficient water
is available in the humid atmosphere of an underground mine to satisfy the
oxidation process.
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Air Control—
Ever since the 1920's, when it was documented that pyrite oxidation was
the cause of acid mine drainage, attempts have been made to prevent air from
entering underground mines'3). The massive mine-sealing program of the 1930's
is but one example. Air control has been accomplished basically by one of
three methods: (l) sealing, plugging, filling, or closing off all portals,
boreholes, openings, cracks, fissures, etc., to prevent air from entering the
mine working; (2) filling the mine working with water as an oxygen barrier,
and (3) filling the mine working with an oxygen-free atmosphere. All of these
methods are only applicable to inactive mines or worked out portions of active
mines.
The debate over the effectiveness of placing an air seal in mine portals
and sealing known openings into an underground mine has been waged for years.
It has been shown many times in laboratory studies that if oxygen is excluded
from the mine, acid mine drainage formation will cease. The major problem
lies in actually sealing an underground mine so that the oxygen level is re-
duced sufficiently to cause a significant decrease in acid formation. In most
cases this cannot be accomplished because of the mine breathing through the
cracks, fissures, and fractures in the overburden material. The effectiveness
of a first-class, air-sealed mine—with all known openings, subsidences, and
the like sealed—is about 50 percent. Mines with shallow cover, outcrops
surface mined, and mines highly subsided would be less conducive to air sealing.
An air-sealed mine requires maintenance to assure the integrity of the seal.
(It)
TABLE 5. EFFLUENT LIMITATIONS, IN MILLIGRAMS PER LITER EXCEPT FOR pH*v '
Average of
Daily Values
Effluent Maximum for 30 consecutive
Characteristic Allowable Discharge Days
Iron, total 7.0 3.5
Manganese, total ^t.O 2.0
Total Suspended Solids 70.0 35-0
pH 6.0 to 9.0
*These limitations are currently being challenged in the courts.
Several investigators have noted that when pyrite is submerged under
water, pyrite oxidation essentially ceases. Mines below drainage that are
permanently flooded do not normally have an acid mine drainage problem. In
recent years, efforts have been made to flood inactive mines above drainage
by utilizing bulkhead seals. Bulkhead seals have been used with heads up to
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35 feet. The effectiveness of this seal depends on the integrity of the
outcrop, the amount of the mine working that is permanently flooded, and the
soundness of the seal. Effectiveness has ranged from 100 percent, where
there is no longer a discharge, to as low as zero—the latter when a working
extended so close to the outcrop that a barrier could not be established.
Water Control—
The basic approach to water control methods is to prevent water from
entering the mine working, where it could flush and transport the products of
pyrite oxidation from the mine. These methods do not have a major effect on
the pyrite oxidation process itself. Since it would be impractical and pro-
hibitively expensive to prevent all water from entering the mine, only major
water sources usually are controlled. Thus the method cannot be 100 percent
effective.
Major sources of water directed to underground mines that can be controlled
are: (l) streams that have been diverted into underground working or lost by
way of subsidence holes, fractures, etc.; (2) surface mines that trap and direct
water into underground mines, and (3) fractures, fissures, and cracks extending
into the mine.
Common techniques used for water control are: (l) grading to facilitate
rapid runoff away from the mine; (2) rechanneling of streams; (3) lining of
streams; (U) filling and compaction of subsidence holes; (5) diversion ditches,
and (6) sealing of boreholes, mine openings, fracture zones, and auger holes
that allow water to enter the mine.
Another technique is aquifer control.
Aquifers above and adjacent to the mine are either drained by gravity or
pumped through wells to dewater the mine. These techniques hold promise, and
are now under study. If proven feasible they could be used for both active
and inactive mines.
In summary, water control methods appear intuitively to be good ways to
reduce acid mine drainage, but their effectiveness has not been well documented.
A unit decrease in flow does not necessarily mean a unit decrease in acid load,
because acid formation may not decrease. The only decrease may be the amount
of acid flushed from the mine.
Filling and Removal—
Other approaches to the underground mine problem have included "fill-it-
up," "knock-it-down," or "remove it."
"Fill-it-up" entails filling the voids within the mine. These methods
are applicable to the inactive situation. Materials that have been suggested
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as fillers are sand, coal refuse, fly ash, municipal waste, and waste residues
such as sludges from acid mine drainage neutralization plants and SCL scrubbers.
The major difficulty with filling any mine is moving material to the void.
Most parts of an inactive mine are inaccessible by means of the passages cut
during mining. Reopening these passages typically would be either impossible
or prohibitively expensive. Thus, the only practical entry is through holes
drilled from the surface. These holes are expensive, limit the size of the
material that can be injected, and limit the distribution of the material as it
enters the void.
In those situations where materials have been placed back into a mine,
control of acid mine drainage has not been the purpose. The major effort has
been to prevent subsidence or control mine fires. A combination of sand and
coal refuse has been used in these situations, generally at high cost. The
effect of mine filling on acid mine drainage control has never been determined.
Acid neutralization sludges and fly ash have been placed in underground
mines as a means of disposing of waste residues, not for the purpose of con-
trolling acid mine drainage. The materials, where they are alkaline, may
neutralize acid water in the mine. They also may coat pyrite surfaces, thus
preventing acid formation. On the other hand, there is a danger that the
material will flow out a mine opening and, if the mine is very acid, that
soluble salts will be leached from the residues. An additional problem is the
large volume of residues required to fill a mine.
The "knock-it-down" concept has been proposed from two standpoints. The
first is to blast the entire mine, causing it to collapse and thus filling all
the voids. This method would have high cost and probably would result in
surface damages. The blasting design and implementation to achieve complete
collapse would be difficult because of the pillars, subsidence, and access to
the mine voids. The second method is to blast alkaline overburden down into
the mine voids. The premise is that as the acid water flows through the
alkaline material, it would be neutralized.
The "remove it" concept also is referred to as "daylighting." Where the
overburden depth is not too great, the underground mine is stripped out, using
surface mining methods. Thus the remaining coal (frmom 25 to 60 percent) is
recovered, and the underground mine is removed. The area then is reclaimed as
a surface mine.
Surface Mines
All the techniques for preventing acid formation are based on the control
of oxygen(5). There are two mechanisms by which oxygen can be transported to
pyrite—convective transport and molecular diffusion.
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The major convection transport source is wind currents that can easily
supply the oxygen requirement for pyrite oxidation at the spoil surface.
In addition, wind currents against a steep slope provide sufficient pressure
to drive oxygen deeper into the spoil mass. A factor to consider is the degree
of slope after regrading. This is especially important on slopes subject to
prevailing winds, since the wind pressure on the spoil surface increases as
the slope increases. Thus, the depth of oxygen movement into the spoil would
increase as the slope increases.
Molecular diffusion occurs whenever there is an oxygen concentration
gradient "between two points, e.g., the spoil surface and some point within
the spoil. Molecular diffusion is applicable to any fluid system, either
gaseous or liquid. Thus, oxygen will move from the air near the surface of
the spoil, where the concentration is higher, to the gas or liquid-filled
pores within the spoil, where it is lower. The rate of oxygen transfer is
strongly dependent on the fluid phases and is generally much higher in gases
than in liquids. For example, the diffusion of oxygen through air is approxi-
mately 10,000 times greater than through water. Therefore, even a thin layer
of water (several millimeters) serves as a good oxygen barrier.
The most positive method of preventing acid generation is the installation
of an oxygen barrier. Artificial barriers such as plastic films, bituminous,
and concrete would be effective, but these have high original and maintenance
costs and would be used only in special situations.
Surface sealants such as lime, gypsum, sodium silicate, and latex have
been tried, but they too suffer from high cost, require repeated application,
and have only marginal effectiveness. The two most effective barrier materials
are soil, including nonacid spoil, and water. The minimum thickness of soil
or nonacid spoil needed is a function of the soil's physical characteristics,
soil compaction, moisture content and vegetative cover. Deeper layers would
be needed for a sandy, dry granular material with large grain size and porosity
than would be required for a tightly packed, moist clay that is essentially
impermeable. Soil thickness should be designed on the basis of the worst
situation—such as a dry soil where oxygen can move more readily through cracks
and pore spaces devoid of water. A "safety factor" should be included to
account for soil losses from such causes as erosion.
Water is an extremely effective barrier when the pyritic material is
permanently covered. Allowing the pyrite to pass through cycles where it is
exposed to oxidation and then covered with water will worsen the acid mine
drainage problem. Water barriers should be designed to account for water
losses such as evaporation and should include at least 30 centimeters (l foot)
of additional depth as a safety factor.
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Additional measures to control acid mine drainage are water control and
inplace neutralization. Water serves not only as the transport media that
carries the acid pollutants from the pyrite reaction sites, but it erodes soil
and nonacid spoils to expose pyrite to oxidation. Facilities such as diversion
ditches that prevent water from entering the mining area and/or carry the water
quickly through the area can significantly reduce the amount of water available
to transport the acid products. Sediment and erosion control are needed both
during and following mining. Terraces, mulches, vegetation, etc., used to
reduce the erosive forces of water are effective measures to prevent further
pyrite exposure. These measures usually are performed during reclamation.
Vegetation not only serves to control erosion, but after it dies, it
becomes an oxygen user through the decomposing process. This further aids the
effectiveness of the barrier. The organic matter that is formed also aids in
holding moisture in the soil.
Alkaline overburden material and agricultural limestone can be blended
with "hot" acidic material to cause inplace neutralization of the acid and
assist in establishing vegetation. In some cases, grading directs acid seeps
to drain through alkaline overburden. These techniques are more applicable
to abandoned surface mines than to current mining, where proper overburden
handling should prevent acid formation. The major exception may be those
situations where an underground mine was breached and an acid discharge formed.
SUMMARY
During active mining operations acid mine drainage point discharges can
be treated from surface and underground mines, coal storage piles, and refuse
dumps to meet the EPA effluent limitations and thus minimize to an acceptable
level the discharge of acidity, and heavy metals to streams. The water may
still be unsatisfactory for some industrial and domestic uses because of its
hardness and dissolved solids content.
The technology for controlling nonpoint acid mine drainage from surface
mines is rather extensive. Current State Laws and the Federal Surface Mining
Control and Reclamation Act of 1977, PL 95-87, provide regulations that will
result in control of acid mine drainage both during and following mining.
While acid mine drainage can be controlled (treated) during active underground
mining, in most cases where the mine is above drainage and the water within
the mine has free drainage, inadequate technology is available to close the
mine to prevent acid mine discharges for extended periods of time (in excess
of 100 years).
13
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FEDERAL AND STATE CONTROL PROGRAMS
All point discharges from coal mines must have a discharge permit from
a state or the U. S. Environmental Protection Agency. Criteria for these
permits are presented in Table 5« To date in many states the issuance of
these permits has lagged for the small mine and enforcement of permit require-
ments has not been extensive.
Of the 21 coal producing states, all but two have some form of a law to
control environmental damages from surface mining. The degree of control
afforded by these laws and regulations vary drastically from state to state.
However, the passage of the Surface Mining Control and Reclamation Act of
1977, PL 95-87, on August 3, 1977, will result in federal environmental
standards for the extraction of coal, both from surface mines and the surface
effects of underground mines. These regulations will go into effect in
February 1978. Many of the provisions of the Act and the subsequent regula-
tions will result in the control of acid mine drainage. The Act under
Section 515(a)(lO) requires: "Minimize the disturbances to the prevailing
hydrologic balance at the mine-site and in associated offsite areas and to the
quality and quantity of water in surface and groundwater systems both during
and after surface coal mining operations and during reclamation by—
Avoiding acid or other toxic mine drainage by such measures as, but
not limited to—
1. preventing or removing water from contact with toxic-producing
deposits;
2. treating drainage to reduce toxic content which adversely affects
downstream water upon being released to water courses;
3. casing, sealing, or otherwise managing boreholes, shafts, and
wells and keep acid or other toxic drainage from entering ground
and surface waters."
The interim regulations propagated in November, 1977 provide the bases
for a strong program to control acid mine drainage. Not only must water
quality discharge standards be met, but specific mining methods and techniques
must be employed that prevent the formation and discharge of acid. Thus,
the regulations, if properly followed and enforced, should result in a signif-
icant reduction of acid discharge from active and inactive surface mines.
State and federal laws for the control of acid discharges for inactive under-
ground mines have not been enacted, although, PL 95-87 does establish an
ABANDONED MINE RECLAMATION FUND which should result in the cleanup of numerous
acid discharges.
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EXTENT AND EFFECT OF ACID MINE DRAINAGE BY 1985 AND BEYOND
Table 6 presents the projections of the National Energy Plan (NEP)
scenario. The NEP prescribes that its Annual Production of Coal will increase
"by 1985 by U.I x 10" BTU over that produced without the plan. This increase
will be met almost entirely from surface mines, in fact underground production
will be less under the NEP than under the Pre-NEP scanario.
Since acid mine drainage is a problem only in Regions 3, U and 5, future
increases in coal production will only impact the acid discharge in these
areas. Acid mine drainage discharges occur from surface mines, mine waste,
and underground mines. During active mining, the control of point discharges
afforded under PL 92-500 and surface mines and mine waste under PL 95-8? should
result in essentially no further discharges of acid to streams. In fact as the
enforcement of these acts becomes better, acid discharges from currently opera-
ting mines should be eliminated. In addition, nonpoint source acid discharges
from surface mines and mine waste should be controlled under the regulations
provided under PL 95-8?. Thus, only underground mine acid discharges that
occur after the mine is closed will increase between 1977 and 1985 and beyond,
because technology to control this problem is not available. A projection of
these increases is presented in Table 7. By 1985, the level of acid discharges
under Pre-NEP and NEP should be similar, because the increase in discharges
will be a result of the closing of currently active mines, but not new mines,
since the lag time to open an underground mine and the mine life will place its
closure after 1985. The impact will almost entirely be felt in Region 3,
because it is in this Region that acid-producing drift mines predominate. The
full impact of the new mines will not be felt until their closure.
TABLE 6 - ANNUAL PRODUCTION OF COAL IN 1015 BTU6
Scenario
Fre-NEP NEP
Underground
1975 7.3 7.3
1985 10.8 9.8
2000 13.3 15-7
Surface
1975 7 = 9 7.9
1985 13.2 18.3
2000 2U.7 29.2
Total
1975 15.2 15.2
1985 2U.O 28.1
2000 38.0 UU.9
NEP - Projection based on President's National Energy Plan, April 29, 1977.
Pre-NEP - Trend based on projections prior to NEP.
15
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TABLE 7 - SULFATE RELEASES ASSOCIATED WITH EASTERN UNDERGROUND MINING*6
lO^ Tons
Region 1975 1985 2000 ^Increase 1975-2000
720
Uo
21
781
836
^5
29
910
1,000
9^
fc5
1,139
38
135
llU
Us
5
Total
*Sulfate is an indicator of acid production.
TABLE 8 - INCREASE OF ACID MINE DRAINAGE OVER 1975 LEVELS (PERCENT)
_ 1985 _ 2000 _
Pre-NEF NEP Pre-NEP NEP
Surface Mine , . . , .
Point Source 0;a 0)aJ oja{ 0)a(
Nonpoint Source o'a' o'a) 0(a) 0^a)
Mine Waste , .
Point Source ojaj ojaj Oja{ ojaj
Nonpoint Source o'a' o' o'a' o'a'
Underground Mines
Point Source
Nonpoint Source
(a) May be a decrease as a result of PL 92-500 and PL 95-87.
(b) Includes inactive mines.
(c) Reflects impact of abandoned mine fund PL 95-87.
By the year 2000, the increase of acid resulting from the increase in
the inactive draft mines will be counter-balanced by the decrease in acid
results from the abandoned mine reclamation program provided for in PL 95^-87.
In addition more mining will be at deeper depths, which do not produce acid
mine drainage upon closure.
16
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SECTION 3
SUBSIDENCE
CAUSE AND EFFECT OF SURFACE SUBSIDENCE
The mining of a substantial quantity of underground material such as
coal creates a void which in turn often produces a condition of instability
within the rock leading to collapse of the overlying rock into the void and
frequently associated surface subsidence. Subsidence begins as soon as the
supports or pillars left in the mine are no longer able to support the over-
burden weight. This condition may occur during the conduct of the mining
operation or may not occur until many years after mining has been completed
and the pillars slowly decay to the critical failure point. Once the over-
lying material falls into the mine void, then cracking and caving proceed
upward over a finite period of time often reaching the surface and causing
considerable damage.
Earth movements at the surface may result in many varied types of damage.
Buildings are more severely affected by the compressive and extensive strains
associated with subsidence than they are by the actual settlement. Highways,
bridges, water and gas lines may be sheared, twisted or broken by strains and
slope changes produced by subsidence. Sewage lines are especially susceptible
to changes of slope that locally reverse their direction of flow. Effects
upon the natural environment can also be quite dramatic. Natural drainage
patterns can be changed resulting in formation or occasional destruction or
swamps. Surface streams often are intercepted by subsided areas or induced
rock fractures resulting in flow into deep mines and loss of surface waters.
In severe cases groundwater supplies may be intercepted and drained into
underlying deep mines. Mine subsidence produces a significant deterioration
of both the natural environment and manmade structures.
No definitive national analysis of the amount of land affected by past
mine subsidence or of the annual or total property damage has been made.
However, an appreciation of the magnitude of the problem can be gained from
the experience of the Coal and Clay Mine Insurance Fund of the Commonwealth
of Pennsylvania. Although only a small portion of undermined and developed
land in Pennsylvania is insured (about 7,500 policies in effect) nearly one
million dollars is paid out annually in damage claims?. Approximately 2,800
separate subsidence incidents involving damage have been reported for the
anthracite fields of Pennsylvania alone^. The U. S. Bureau of Mines has
estimated subsidence costs, both surface damage and control costs, for a
twelve county area in Western Pennsylvania for the year 1968. Total surface
damages from active underground mining of coal for this twelve county area
were estimated at $295,000 with an additional $^.3 million of coal left in
place to minimize potential surface damage^. These figures would be much
higher under current economic conditions.
17
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Many interrelated factors influence surface subsidence and the rate at
which subsidence occurs in a particular location. Figure 1 illustrates some
of the major geological and mining conditions that are related to initial
underground mine roof failures and resulting subsidence10. Once roof failure
has occurred many interrelated factors such as intensity and depth of mining,
type and amount of roof support provided, composition, thickness and number
of coal beds mined, composition, thickness and degree of consolidation of the
overburden and structural features such as steepness of dip of the coal beds
and presence of planes of weakness within the rock strata all affect the
amount and rate of subsidence. These factors are summarized in Figure 2.
Each instance of subsidence is unique because the many interrelated fac-
tors listed above can be varied individually and combined in a variety of ways.
Although the surface appearance of subsidence features can vary greatly,
occurrences can generally be classified as pothole, linear or regional as
defined in Table 9.
18
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SAG AND ROOF COLLAPSE
SAG AND PILLAKSQUEEZE
PILLAR COLLAPSE OR PILLAR REMOVAL
DOMING- TYPE ROOF FALL
MINING TOO FAR VPDIP
MINING INTO FA VL T
MINING TOO CLOSE TO ALLUVIAL
OR GLACIAL OVERBURDEN (A )
MINING TOO CLOSE TO AN OVER- OR
UNDER-LYING MINED-OUTSEAM B
MINING INTO CHANNEL SAND OR OTHER
HETEROGENEOUS ROCK STRA TA
Figure 1. Geological and Mining Conditions Belated to Underground Roof
Failures and Resulting Surface Subsidence-^
19
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ro
o
SOIL MOISTURE
SURFACE HYDROLOGIC
CONDITIONS
BURIED GLACIAL AND
ALLUVIAL CHANNELS
SURFICIAL COVER -
TYPE AND THICKNESS
GROUNDWATER CONDITIONS
SUB-SURFACE
HYDROLOGIC CONDITIONS
OVERLYING STRATA -
LITHOLOGY AND THICKNESS
BEARING STRENGTH OF
COAL AND PILLARS
ROOF ROCK - STRENGTH,
THICKNESS AND HOMOGENEITY
EXPANDABLE UNDERCLAYS
DIP OF COAL SEAM
AND ROCK STRATA
LITHOLOGIC IN HOMOGENEITIES
CHANNEL FILLS, DIKES, GOUGE
ZONES, FACIES CHANGES
NUMBER OF SEAMS MINED
AND DEGREE OF EXTRACTION
FAULTS, FRACTURES, JOINTING
Figure 2. Factors Affecting the Amount and Rate of Surface Subsidence
10
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TABLE 9 - SURFACE SUBSIDENCE CLASSIFICATION AND MORPHOLOGICAL CHARACTERISTICS
10
Type
Pattern
Surficial Characteristics Width/Depth Ratio
Geological
Character
0)
01 O
H a
O 0)
-P -H
O CQ
CQ
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CONTROLLING THE CAUSE AND EFFECTS OF SUBSIDENCE
Although there is no simple or universal solution to all of the problems
caused by subsidence, various means are available to control surface damages-'--'-
from future mining. Two basic approaches must be coordinated and applied to
each situation. The first approach involves controlling the mining activity
while the second involves controlling the nature of surface development. The
specific subsidence damage control measures most suitable depend upon the
extent of surface development that would be threatened by subsidence. For
a heavily built up area underlain by mineable coal, the subsidence control
measures must be aimed at preventing surface subsidence by controlling the
mining operation to minimize surface disturbance. For nondeveloped areas the
emphasis must be placed upon delaying surface development until the coal
resource is extracted and the area has undergone subsidence and stabilized.
Future mining of high and medium density development areas in a manner
which would result in future subsidence could have a major economic impact
which would be unacceptable in terms of both individual impact and impact on
the general welfare of the community1^. Such damage can occur, however, if
the right of surface support is not held by the surface development owner, or
if proper enforcement of regulations relative to mining techniques is not
achieved in those areas where surface support may be required^. Mining
technology presently exists which would generally permit recovery of approxi-
mately 50 percent of the coal while substantially reducing surface subsidence.
Conventional room and pillar mining can be modified to provide surface
support in many cases by accepting much lowered extraction ratios with careful
attention to design, size and spacing of support pillars. This method has
been used successfully in Western Pennsylvania where present law requires the
mine operator to provide surface support for some structures. Panel and
pillar mining likewise can be adapted to minimize subsidence damage and is
compatible with longwall mining-1-^. Shortwall mining techniques can also be
adapted to provide surface support-^. The critical considerations in utilizing
these methods involve abandonment of adequate coal for support (about 50%),
adequate pillar size so that deterioration of pillars will not cause subsidence
and careful design of pillar placement to support the overburden. Other
techniques have been proposed to reduce the impact of subsidence by minimizing
the compressive and extensive strains that do most of the damage. These
methods include extraction face control measures to control the propagation
rate of the subsidence trough and harmonious extraction methods based on the
principal of overlapping compressive and extensive strains to achieve a
cancellation effect1^. In addition, various backfilling measures such as
hand packing, mechanical backfilling, hydraulic backfilling and pneumatic
backfilling can be utilized to reduce the amount of surface subsidence-^.
Although backfilling may appear to be an attractice subsidence control measure,
22
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the high costs involved, at least one to four dollars per ton of coal mined
under favorable conditions-'-", pose a serious question of economic viability.
Although methods exist to permit mining of a portion of the coal under
developed areas without inducing subsidence, it is not likely that mine
operators will voluntarily abandon a large percentage of their mineral resource
unless they are required to provide surface support. The key to the problem
is the recognition that land ownership and rights can be divided into three
estates: surface rights, mineral rights, and surface support rights12. Each
of these three estates or ..ughts can be held in separate ownership. Unless
the surface property owner is assured the right of surface support it is
likely that future mining under developed areas will produce substantial damage
similar to that which has occurred in the past. If the mine operator must pro-
vide surface support then approximately 50 percent of the mineral must be
abandoned which raises a key policy issue in terms of meeting the Nation's
energy needs.
For situations where mineable coal exists under sparcely or undeveloped
areas the solution is simpler in concept but may prove equally difficult to
implement. Future development of these areas should be controlled to preclude
high or medium density development which may be subjected to future subsidence.
It is recommended that prior to approval of any surface development in areas
underlain by coal (or other deep mineable mineral) that the potential for
future mining and subsequent subsidence be reviewed. In cases where the
right to surface support has been separated from the surface ownership a
potential threat to life and property exists if development occurs prior to
mining. Therefore, it is suggested that in areas where mineral rights have
been severed from the property rights the property owner should be required to
certify the specific status of the rights to surface support prior to sub-
division or land development for which any state or local permit may be
required. Further, if the right to surface support is not held by the property
owner and deep mining of the area is likely then the permit for such surface
development may be denied1?.
Just as it is impractical to allow development to occur in areas where
future mining may present a real threat of subsidence it is equally impractical
to consider that mining should be allowed to occur in a manner that the result-
ant subsidence potential is of a nature which cannot be defined in terms of
time and extent. Regulation of the mining industry should be established
which will avoid the creation of a potential subsidence problem which will in-
cumber the subsequent surface use of land for extended or indeterminate periods
of time. The principal problem presented with regulation of development in
such cases is that it is impossible to predict (based on current and projected
data) when subsidence may occur. This precludes development of the land for
an extended period unless very expensive stabilization measures are implemented.
Two general approaches to mining techniques should be considered-L f.
23
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1. Mine in a manner that will not cause immediate or long-term subsidence
problems.
2. Mine in a manner which would result in immediate and complete subsidence.
Under the first approach it would probably be necessary to limit
extraction to 50 percent or less, based on current generally accepted engineer-
ing principals. Under the second approach of total extraction or near total
extraction, it would be necessary to insure that the surface is left in or
returned to a usable state. Flexibility in such regulation must, however, be
maintained since physical problems may exist which would preclude implementa-
tion that would achieve the desired result. Trade-off and alternative
approaches must be accommodated to effectively deal with individual case
situations-'-^.
FEDERAL AND STATE PROGRAMS TO CONTROL SUBSIDENCE
If no actions are taken by the Federal or State governments to control
subsidence problems from future mining, then it is likely that present prob-
lems will be compounded and eventually remedial action will become necessary
by government agencies. A 1976 U. S. Bureau of Mines report indicated that
four backfilling demonstration projects were currently in progress for aban-
doned mine subsidence control with an estimated cost of seven million
dollars . The U. S. Bureau of Mines estimates that it will be involved in
3 to 5 subsidence control projects (for abandoned mines) per year for the next
5 to 10 years . Presently there is no federal program to control creation of
future subsidence problems. Only one state, Pennsylvania, has enacted legis-
lation specifying the separate responsibilities of surface owners and mine
operators for subsidence damage-^. Under Pennsylvania law, which applies
only to the bituminous fields, a mine operator is responsible for damage to
surface structures that were in existence prior to implementation of the law
(1966). Surface structures built after 1966 in subsidence-prone areas can be
protected by purchasing coal support from the mine operator. Generally the
practice of conveying ownership of minerals separate from surface ownership
with the right to extract the mineral regardless of surface effects has placed
the cost of repairing subsidence damage upon the surface owner.
The new surface mining law, Public Law 95-8?, of August 3, 1977, addressed
the subsidence problem in a general manner under Section 5l6(b)(l) which states
in part
"Each permit issued under any approved State or Federal
program pursuant to this Act and relating to underground
coal mining shall require the operator to—
-------
adopt measures consistent with known technology in
order to prevent subsidence causing material damage
to the extent technologically and economically
feasible, maximize mine stability, and maintain
the value and reasonably foreseeable use of such
surface lands except in those instances where the
mining technology used requires planned subsidence
in a predictable and controlled manner: Provided,
that nothing in this subsection shall be construed
to prohibit the standard method of room and pillar
mining"
In order to adequately address the subsidence problem a concerted effort
is needed by all levels of government, Federal, State and local to coordinate
the surface development with the extraction of the coal so that maximum use
can be made of each resource without conflicting with development of the
other. The alternative of waiting until subsidence actually occurs before
taking action would involve accepting extensive property damage and would
negate many of the benefits that could be achieved by preventive action2^.
Subsidence occurring in critical areas could create conditions potentially
injurious or fatal to local residents-^.
EXTENT OF POTENTIAL SUBSIDENCE BY 1985 AND BEYOND
The extent to which future mining will increase the subsidence problem
depends upon the actions taken to prevent creation of future subsidence prob-
lems by coordinating surface development and mineral extraction activities.
If no action is taken then the U. S. Bureau of Mines has estimated that by
the year 2000 over 1.5 million acres of land will be affected by subsidence
with resulting property damage of at least two billion dollars2-'-. The energy
shortage promises to even further aggravate subsidence problems as the demand
for coal rapidly increases. Since the majority of our Nation's coal reserves
can be mined only by underground methods, the potential for surface subsidence
will become even greater, especially with the wider use of total coal extrac-
tion methods such as longwall mining22.
To estimate the impact of subsidence from increased underground mining
it is useful to examine future temporary land use demand for deep mining as
an indicator of deep mining activity and thereby of subsidence potential.
Table 10 provides an estimate of increasing land use for deep mining by the
years 1985 and 2000. Assuming that increased land use parallels increased
deep mining activity and that subsidence from future mining follows the
pattern from past mining, then annual increases in subsidence of 22 percent
for Region 3, 9 percent for Region U, and k2 for Region 5 may be expected by
1985. Likewise increases of It8 percent for Region 3, lUl percent for Region U
25
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and 121 percent for Region 5 may "be expected "by the year 2000. The major
impact will be in the major coal-producing states indicated in Table 10. A
similar projection can be made from Table 11 which presents estimates of
increased coal production from underground mining for the years 1985 and 2000
including the estimated effect of the President's National Energy Plan (NEP).
Assuming subsidence parallels the rate of underground coal production then
subsidence occurrence by 1985 may increase by ^8 percent without the NEP
or 3^ percent under the NEP. The reason for the smaller percentage increase
under the NEP is due to the expected initial greater emphasis upon surface
mining of coal, partly at the expense of underground mining, that would result
under the NEP. By the year 2000 this initial emphasis on surface mining
rather than underground mining will be overcome and increases in subsidence
occurrences of 115 percent under the NEP and 82 percent without the NEP are
estimated. These estimates are in general agreement with those for Regions 3,
U and 5 based on the previous table. Subsidence from underground coal mining
is expected to be negligible for other regions since underground coal mining
is substantially confined to Regions 3, ^ and 5 and particularly to those
states listed in Table 10. If effective coordination between underground coal
mining and surface development is accomplished then these increases in sub-
sidence and their associated effects can be substantially reduced but partly
at the expense of reduced resource recovery.
TABLE 10 - ANNUAL TEMPORARY LAND USE ASSOCIATED WITH EASTERN UNDERGROUND MINING^
Kr Acres
Region 1975 1985 2000 % Increase 1975-2000
3 65 79 96 U8
U 3U 37 82 lltl
5 19 27 U2 121
Major coal-producing states within each region:
Region 3 - Virginia, West Virginia, Pennsylvania, and Maryland
Region k - Alabama, Tennessee, and Kentucky
Region 5 - Illinois, Ohio, and Indiana
TABLE 11 - ANNUAL PRODUCTION OF COAL IN 1015 BTU FROM UNDERGROUND COAL MINES^
Pre-NEP NEP
1975 7.3 7.3
1985 10.8 9.8
2000 13.3 15.7
NEP - Trends resulting from the President's National Energy Plan (U-29-77).
Pre-NEP - Trends without impact of NEP.
26
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SECTION IV
REFERENCES
1. Appalachian Regional Commission, Acid Mine Drainage in Appalachia,
House Document No. 91-l80, 91st Congress, 1st Session, Washington, DC.
1969.
2. Environmental Protection Agency. Processes, Procedures and Methods
to Control Pollution from Mining Activities. Publication EPA-430/9-73-
011. Washington, DC. 1973.
3. Environmental Protection Agency. Inactive and Abandoned Underground
Mines — Water Pollution Prevention and Control. Publication EPA-lAO/9-
75-007. Washington, DC. 1975.
h. Environmental Protection Agency. Coal Mining — Effluent Guidelines and
Standards. Federal Register, Thursday, May 13, 1976.
5. Grim, E. C. and Hill, R. D. Environmental Protection in Surface Mining
of Coal. Environmental Protection Agency Publication EPA-670/2-7lt-093 .
Washington, DC.
6. Annual Environmental Analysis Report, Volume I — Technical Summary,
prepared by the Mitre Corporation for the Assistant Administrator for
Environment and Safety, Energy Research and Development Administration
(now part of the Department of Energy). Washington, DC. 1977.
7. A Comprehensive Program for Dealing with Mine Subsidence. ARC Report
73-163-2559 » prepared by Michael Baker, Jr., Inc., Beaver, Pennsylvania,
and the Institute of State and Regional Affairs, The Pennsylvania State
University, Middletown, Pennsylvania, for the Appalachian Regional
Commission, Washington, DC, and the Pennsylvania Department of Environ-
mental Resources, Harrisburg, Pennsylvania. 1976. Chapter 3, page 22.
8. Relationship between Underground Mine Water Pools and Subsidence in the
Northeastern Pennsylvania Anthracite Fields. ARC Report 73-111-2553,
prepared by A. W. Martin Associates, Inc., King of Prussia, Pennsylvania,
for the Appalachian Regional Commission, Washington, DC and the
Pennsylvania Department of Environmental Resources, Harrisburg,
Pennsylvania. 1975- Appendix B.
9. Cochran,. William. Mine Subsidence — Extent and Cost of Control in a
Selected Area. Information Circular 8507, U. S. Bureau of Mines,
Washington, DC. 1971. Page 1.
27
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10. Use of Photo Interpretation and Geological Data in the Identification of
Surface Damage and Subsidence, ARC Report 73-111-255^, prepared by Earth
Satellite Corporation, Washington, DC, for the Appalachian Regional
Commission, Washington, DC, and the Pennsylvania Department of Environ-
mental Resources, Harrisburg, Pennsylvania. 1975. pp. 35-37.
11. Cochran, William. Mine Subsidence—Extent and Cost of Control in a
Selected Area. Information Circular 8507, U. S. Bureau of Mines,
Washington, DC. 1971. Page U.
12. A Comprehensive Program for Dealing with Mine Subsidence. ARC Report
73-163—2559, prepared by Michael Baker, Jr., Inc., Beaver, Pennsylvania,
and the Institute of State and Regional Affairs, The Pennsylvania State
University, Middletown, Pennsylvania, for the Appalachian Regional
Commission, Washington, DC, and the Pennsylvania Department of Environ-
mental Resources, Harrisburg, Pennsylvania. 1976. Chapter 6, page H8.
13. Ibid., Chapter 3, page 36.
lU. Grey, R. E.,Gamble, J. C., McLaren, R. J., and Rodgers, D. J. State of
the Art of Subsidence Control. ARC Report 73-111-2550, prepared by
General Analytics, Inc., Monroeville, Pennsylvania, for the Appalachian
Regional Commission, Washington, DC, and the Department of Environmental
Resources, Harrisburg, Pennsylvania. 197^. Part 2, page 52.
15. Ibid., Part 2, pages 56-59.
16. Underground Disposal of Coal Mine Wastes. A report to the National
Science Foundation by the National Academy of Sciences, Washington, DC.
1975. Page 6.
17. A Comprehensive Program for Dealing -with Mine Subsidence. ARC Report
73-163-2559, prepared by Michael Baker, Jr., Inc., Beaver, Pennsylvania,
and the Institute of State and Regional Affairs, The Pennsylvania State
University, Middletown, Pennsylvania, for the Appalachian Regional
Commission, Washington, DC, and the Pennsylvania Department of Environ-
mental Resources, Harrisburg, Pennsylvania. 1976. Chapter h, pages l)-9-51«
18. Staff, U. S. Bureau of Mines. Final Environmental Impact Statement—
Surface Subsidence Control in Mining Regions. U. S. Department of the
Interior. Washington, DC. 1976. pp. 5-5.
19. Ibid., page 53.
20. Ibid., page 56.
28
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21. Use of Photo Interpretation and Geological Data in the Identification
of Surface Damage and Subsidence. ARC Report 73-111-255^, prepared by
Earth Satellite Corporation, Washington, DC, for the Appalachian Regional
Commission, Washington, DC, and the Pennsylvania Department of Environ-
mental Resources, Harrisburg, Pennsylvania. 1975. Page 1.
22. Ibid., page 101.
29
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-78-068
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
ACID MINE DRAINAGE AND SUBSIDENCE:
INCREASED COAL UTILIZATION
EFFECTS OF
5. REPORT DATE
April 1978 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Ronald D. Hill arid Edward R. Bates
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Industrial Environmental Research' Lat>.
Office of Research and Development
U. S. Environmental Protection Agency
Cincinnati, Ohio 1+5268
- Cinn, OH
10. PROGRAM ELEMENT NO.
1BB610
11, CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as #9
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The increases abqve 1975 levels for acid mine drainage and subsidence for
the years 1985 and 2000 based on projections of current mining trends and the
National Energy Plan are presented. No increases are projected for acid mine
drainage or waste since enforcement under present laws should control this
problem. The increase in acid mine drainage from underground mines is pro-
jected to be 16 percent by 1985 and 10 percent by 2000. The smaller increase
in 2000 over 1985 reflects the impact of the PL 95-8? abandoned mine program.
Mine subsidence is projected to increase by 3^ and 115 percent respectively
for 1985 and 2000. This estimate assumes that subsidence will parallel the
rate of underground coal production and that no new subsidence
control measures are adopted to mitigate subsidence occurrence.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Coal Mining
Energy
National Energy Plan
Acid Mine Drainage
Mine Subsidence
68D
8. DISTRIBUTION STATEMENT
Release to the Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
38
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
30
-U.S. GOVERNMENT PRINTING OFFICE: 1978-757-l'tO/6803 Region No. 5-11
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