EPA-680/4-74-003
JULY 1974
Environmental Monitoring Series
.•
RATIONALE AND METHODOLOGY FOR MONITORING
GROUNDWATER POLLUTED BY MINING ACTIVITIES
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, Environmental Protec-
tion Agency/ have been grouped into five series. These five broad categories were
established to facilitate further development and application of environmental tech-
nology. Elimination of traditional grouping was consciously planned to foster tech-
nology transfer and a maximum interface in related fields. The five series are:
1. Environmental Health Effects Research
2» Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies.
This report has been assigned to the ENVIRONMENTAL MONITORING series. This
series describes research conducted to develop new or improved methods and instru-
mentation for the identification and quantification of environmental pollutants at the
lowest conceivably significant concentrations. It also includes studies to determine
the ambient concentrations of pollutants in the environment and/or the variance of
pollutants as a function of time or meteorological factors.
EPA REVIEW NOTICE
This report has been reviewed by the Office of Research and Development, EPA, and
approved for publication. Approval does not signify that the contents necessarily re-
flect the views and policies of the Environmental Protection Agency, nor does men-
tion of trade names or commercial products constitute endorsement or recommendation
for use.
V
NOTE: This report was previously printed for limited distribution as
EPA 600/4-74-003, July 1974.
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EPA 680/^-7^-003
July 197^
RATIONALE AND METHODOLOGY
FOR MONITORING GROUNDWATER
POLLUTED BY MINING ACTIVITIES
by
Don L. Warner
Consulting Geological Engineer
Contract No. 68-01-0759
ROAP No, 22AAE
Program Element No. 1HA326
Project Officer
George B. Morgan
Monitoring Systems Research and Development Laboratory
National Environmental Research Center
Las Vegas, Nevada
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 891 U
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ABSTRACT
The principal objective of the report is to document the rationale and related
methodology for monitoring groundwater pollution caused by mining and mineral
processing.
The various mining methods and the ways in which they interact with ground-
water are analyzed. Because of the broad range of mining activities and diversity
of geologic and hydrologic settings, monitoring programs for mineral operations
must be individually considered.
Some mines and waste disposal areas will continue to be pollution sources long
after the mines have closed. This important fact must be taken into account when
designing a monitoring program.
Technology for at-source control of water pollution from mining is reviewed,
including factors that influence groundwater. In some cases, methods that effect
an improvement in surface water quality may cause deterioration in groundwater qual-
ity; therefore, observation of groundwater quality may be necessary when such methods
are used.
Existing State and Federal laws for control of mine drainage pollution are dis-
cussed. An important defect of most such laws and regulations is their inability to
influence the design, permitting, or abandonment of underground mines on the basis
of water pollution considerations.
This report was submitted in partial fulfillment of Task 3, Contract Number
68-01-0759, by General Electric—TEMPO under the sponsorship of the Environmental
Protection Agency. Work was completed as of June 1974.
Ill
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ACKNOWLEDGEMENTS
*
Mr. Charles F. Meyer of General Electric—TEMPO was the mana-
ger of the project under which this report was prepared. Mr. Meyer,
Mr. Edward J. Tschupp, and Dr. Richard M. Tinlin of TEMPO provided
assistance in acquiring bibliographic material and Mr. Meyer, Dr.
Tinlin, and Dr. David Kleinecke in reviewing and editing the manuscript.
Portions of this report dealing with monitoring draw upon material
prepared for the project by Dr. David K. Todd, Consulting Engineer,
Berkeley, California.
The following officials of the Environmental Protection Agency were
responsible for administration and technical guidance of the project:
Office of Research and Development (Program Area Management)
Dr. Henry F. Enos
Mr. Donald B. Gilmore
Mr. John D. Koutsandreas
NERC —Las Vegas (Program Element Direction)
Mr. George B. Morgan
Mr. Leslie G. McMillion
* General Electric Company—TEMPO, Center for Advanced Studies,
P. 0. Drawer QQ., Santa Barbara, California 93102
IV
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TABLE OF CONTENTS
Page
ABSTRACT Hi
ACKNOWLEDGEMENTS iv
LIST OF ILLUSTRATIONS vi
SECTION I - CONCLUSIONS 1*
SECTION II - RECOMMENDATIONS 4
SECTION III - INTRODUCTION 6
SECTION IV - MINING METHODS 7
Conventional Underground Mining 7
Surface Mining 10
Solution Mining 15
Leaching 18
In-Situ Combustion 21
Waste Disposal 21
SECTION V - EXTENT OF MINING ACTIVITIES 24
SECTION VI - MINING HYDROLOGY AND GROUNDWATER POLLUTION 26
SECTION VII - METHODS FOR CONTROL AND PREVENTION OF
GROUNDWATER POLLUTION 44
Underground Mines 45
Surface Mining 52
SECTION VIM - MONITORING 57
Evaluation of Proposed Mining Activities 57
Monitoring During Operation 62
Post-Operational Monitoring 67
SECTION IX - LAWS AND REGULATIONS 68
SECTION X - REFERENCES 70
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LIST OF ILLUSTRATIONS
Figure No. Title Page
1 Means of entry to underground bituminous coal mines. 8
2 Room and pillar mining method with regular pillars. 9
3 Square-set mining methods used under conditions requiring
maximum support for ore and walls. 10
4 Diagram illustrating principles involved in application of
block caving method. 11
5 Area surface mining method. 12
6 Contour strip mine after regrading. 13
7 Single-well systems for solution mining of halite. 16
8 Operation of a sulfur well during solution mining of sulfur
by the Frasch Process. 17
9 Flood-leaching mining system. 20
10 Schematic representation of an in-situ retorting operation. 22
11 Cone of depression resulting from mine dewatering. 27
12 Drainage patterns from underground coal drift mines. 30
13 Relationship of underground coal mines to groundwater
flow systems. 30
14 Diagram showing how contaminated water can be induced
to flow from a surface source to a well. 31
15 Diagram showing how a pumping well can cause a fresh-water
aquifer to be contaminated by saline water from underlying
rocks. 33
16 Diagrammatic section across the Piceance Basin. 35
17 Diagram showing migration of saline water caused by
dewatering in a fresh-water aquifer overlying a saline-water
aquifer. 37
18 Diagram showing possible mode of entry of windblown wastes
into an aquifer. 43
VI
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ILLUSTRATIONS
Figure No. Title Page
19 Preplanned flooding of underground drift mines. 46
20 Interception of mine water by pumping of overlying
aquifers. 50
21 Interception of mine water by gravity wells. 51
22 Impoundment of water in a contour strip mine by use of
a low-wall barrier. 53
23 Control of infiltration by implacement of impermeable
material. 54
24 Control of lateral flow through strip mine spoils by
implacement of impermeable material. 55
25 Relocation of pollution-forming material in the spoil bank
of a contour strip mine. 55
VII
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SECTION I
CONCLUSIONS
The production of minerals and mineral fuels by mining has long been
the basis for much of the American economy. Many mining activities will
increase in the future, some of them very substantially.
New mining technologies are receiving greater emphasis.
Mining will move into new geographic areas, such as those where the
western coal fields and oil shale deposits occur.
Like other industries, mining creates environmental impacts, of
which one may be groundwater pollution. Many documented cases show
how groundwater pollution can result from mining and related activities.
Other as-yet undocumented possibilities can be anticipated, partly be-
cause some of the new technologies have a greater potential for polluting
groundwater.
Because groundwater is also a valuable natural resource, every ef-
fort should be made to anticipate and prevent or minimize groundwater
pollution during mining. Monitoring, in the broadest sense, is a means
for achieving this objective.
Mining and mineral processing operations include an extremely broad
range of activities that occur in diverse geologic and hydrologic settings;
therefore, it is necessary to consider each mineral operation individually
in order to devise the most cost-effective monitoring scheme.
Groundwater pollution from mining operations may be caused by the
discharge of pollutants into the hydrologic system, just as with other in-
dustrial plants. On the other hand, groundwater pollution may result from
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CONCLUSIONS
natural chemical reactions that occur in underground mines, the spoils
of surface mines, or mine and mill waste-disposal areas.
An important characteristic of mining operations is that some mines
and waste-disposal areas will continue to be pollution sources long after
the mines and processing plants have closed.
These characteristics are such that a philosophy of monitoring dif-
ferent from that applied to other pollution sources is required. In partic-
ular, it is desirable to anticipate the potential for water pollution prob-
lems and to plan for closing of underground mines and the reclamation of
surface mines and waste-disposal areas in advance of the opening of new
mines. If predictions indicate that water quality problems may occur
and mining is nevertheless initiated, then changes in water quality can
be followed to provide information on the location and intensity of pollu-
tion for use in groundwater management.
Some methods for surveillance of groundwater quality during the
operation of a mine and its auxiliary facilities are water sampling, meas-
urement of groundwater levels, geophysical measurements, remote sens-
ing, monitoring of storage tanks and pipelines, monitoring of solid and
liquid waste-disposal areas, and maintenance of material balances.
Sampling points used in a monitoring program should be located on
the basis of the hydrogeologic framework of the areas. Mathematical
models may provide a means for optimizing the location of sampling
points, by reducing the number of points and helping to determine the
frequency of sampling required. The frequency of sampling required
will depend not only on site hydrogeology, but also on other factors such
as the nature of the pollution source and the hazard of the pollutants in-
volved. Analyses performed on water samples should be for specific
pollutants because of their hazard, persistence, concentration, ease of
identification, or other characteristic features.
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CONCLUSIONS
The various techniques for control of water pollution from mining
may generally be classified as either at-source or treatment methods.
Insofar as groundwater pollution is concerned, the at-source techniques
are of interest because such techniques may involve modification of the
groundwater system in either a beneficial of detrimental way, and obser-
vation of quality changes may be needed to verify the effect on groundwater
of the controls that are applied.
A variety of different statutory means are available by which the
States and Federal government can control water pollution from mining
activities. Perhaps the most important defect of such laws and regula-
tions is their inability, in most cases, to influence the design, permitting,
or abandonment of underground mines on the basis of water pollution con-
siderations. A particular defect in Federal laws in the inability to regulate
the environmental aspects of mining done under the general mining law of
1872.
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SECTION II
RECOMMENDATIONS
More attention should be given to the actual and the potential effects
of mining activities on the quality of ground-water resources. Water-
quality inventories in mining areas should routinely consider groundwater
as well as surface water.
Provisions should exist in State and Federal laws for requiring the
potential effect of mining activities on groundwater to be examined prior
to opening of a new mine, so that impacts may be considered and mine
design influenced where necessary. Pre-mining plans should include the
anticipated method of mine closing and site reclamation. Groundwater
quality observation should be a part of the environmental program of the
mining company whenever groundwater quality changes are possible.
After mining is completed, continued surveillance of groundwater quality
may be desirable or even essential in some mining areas.
A monitoring program should be based on the geology and hydrology
of the individual mine site. Analysis and modeling of the groundwater
flow system should be considered as a possible means for optimizing a
monitoring system by minimizing cost and maximizing the effectiveness
of monitoring.
Research is needed to better define the effect on groundwater of some
of the newer mining technologies, such as in-situ leaching and combustion.
Also, the particular groundwater problems that may develop in potentially
large new geographic mining regions, such as those where the western
coal and oil shale deposits occur, should be very carefully studied now,
before substantial mining begins, to avoid creation of extensive and perhaps
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RECOMMENDATIONS
irreversible water quality damage. The Appalachian coal fields provide
a vivid and eternal example of the water quality damage that can result
when mining is undertaken without adequate prior consideration of and
adjustment for impacts on water resources.
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SECTION III
INTRODUCTION
This report, concerning the monitoring of groundwater pollution
from mining activities, was prepared tinder a contract between the En-
vironmental Protection Agency and General Electric —TEMPO, for for-
mulation of a concept and methodology for monitoring the quality of the
nation's groundwater resources, in support of developing and enforcing
groundwater quality standards.
The principal objective of the report is to document methodology
for monitoring of groundwater pollution from mining and mineral process-
ing. Monitoring of groundwater is often thought of as the observation of
groundwater quality by the sampling of wells and springs. In this case,
monitoring is meant to include the full spectrum of considerations given
to determining the effects of a mine and its associated facilities on
groundwater quality, from planning through operation and finally aban-
donment. A secondary objective of the report is to organize and present
the subject matter in an integrated form, a task that has not been pre-
viously undertaken.
Because mining and mineral processing encompass such a broad
field of activities and these activities occur in diverse geologic and hy-
drologic settings, the report includes discussion of the various mining
methods and their extent and the observed and potential mechanisms
for groundwater pollution related to each. Known methods for control
of water pollution from mining are generally discussed, because some
of the methods involve interaction with the groundwater system. A brief
review of existing laws and regulations for control of water pollution
from mining is presented.
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SECTION IV
MINING METHODS
To obtain an organized view of the potential for groundwater pollu-
tion from mining activities, the various mining methods must be under-
stood sufficiently to determine how the mines will interact with ground-
water systems. Mining is broadly classified as surface or underground
mining, but there are methods that are in use today, or which may be
in use in the future, that do not fit into the conventional concept of min-
ing, and are sufficiently different to warrant individual discussion.
Such methods include solution mining, leaching, and in-situ retorting
or combustion of fossil fuels. Furthermore, in the case of leaching
and in-situ retorting or combustion of fossil fuels, the use of nuclear
explosives as an energy source is sufficiently different from other meth-
ods to warrant separate consideration.
CONVENTIONAL UNDERGROUND MINING
Conventional underground mining methods are considered here to
be those in which underground entry is made by a drift, slope, or shaft
(Figure 1), the rock broken by drilling and blasting or with mining ma-
chines, and the broken rock removed from the mine for processing.
Underground mining methods are usually discussed by the type of extrac-
tion process and the means of support of the roof and walls. Underground
openings created by the extraction of ore are called stopes. Stoping meth-
ods are classified as those in which stopes are open or naturally supported,
those in which stopes are artificially supported, those in which stopes are
allowed or encounraged to cave, and combinations of supported and caved
stoping methods.
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MINING METHODS
SHAFT MINE
DRIFT MINE
SLOPE MINE
SURFACE MINE
Figure 1. Means of entry to underground bituminous coal mines.
8
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CONVENTIONAL
UNDERGROUND MINING
An example of the open or naturally supported stoping method is
room and pillar mining of coal, oil shale, limestone, and other bedded
minerals (Figure 2). Such methods are used where the openings are suf-
ficiently stable so that little or no artificial support is needed during
mining. In coal mining, however, it is usually planned to ultimately re-
move as many pillars as possible and collapse of the mine roof will then
occur after mining is completed.
Supported stoping methods are those in which materials such as
waste rock, timber sets, steel sets, jacks, liners, and roof bolts are
used to support the openings. The square-set timbering method, which
is used under conditions requiring maximum, support, is an example
(Figure 3). The openings in the timber sets are filled, so that after min-
ing is completed, only a minimal amount of collapse of the mine workings
can occur. A number of metal mines in the United States have used this
and similar mining methods.
Figure 2. Room and pillar mining method with regular pillars
(Lewis and Clark, 1964).
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MINING METHODS
Figure 3. Square-set mining methods used under conditions requiring maximum
support for ore and walls (Lewis and Clark, 1964).
Caving methods are used where ore bodies are large and have a
capping which may be caved. Block caving (Figure 4) exemplifies caving
methods. When caving methods are used, subsidence is an inevitable
consequence, and a large collapsed area, open to the surface, may be
the final result. A number of large copper deposits in the western United
States have been mined by block caving.
SURFACE MINING
"Surface methods employed to recover minerals and fuels are gen-
erally classified as (1) open pit mining (quarry, open case); (2) strip
mining (area, contour); (3) auger mining; (4) dredging; and (5) hydraulic
mining" (U.S. Department of Interior, 1965).
10
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SURFACE MINING
ORIGINAL SURFACE
CAVED SURFACE
BLOCK
^-WEAKENING
DRIFT
DEVELOPMENT
BLOCK
Figure 4. Diagram illustrating principles involved in application of
block caving method (Lewis and Clark, 1964).
Open pit mining is exemplified by quarries producing limestone,
sandstone, marble, and granite; sand and gravel pits; and large exca-
vations opened to produce iron and copper. Usually, in open pit mining,
the amount of overburden removed is proportionately small compared
with the quantity of ore recovered. Another distinctive feature of open
pit mining is the length of time that mining is conducted. In stone quarry-
ing, and in open pit mining of iron ore and other metallics, large quan-
tities of ore are obtained within a relatively small surface area because
of the thickness of the deposits. Some open pits may be mined for many
years—50 or more. However, since coal beds are comparatively thin,
the average surface coal mine has a relatively short life.
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MINING METHODS
Area strip mining (Figure 5) usually is practiced on relatively flat
terrain. A trench, or "box cut, " is made through the overburden to ex-
pose a portion of the deposit, which is then removed. Succeeding paral-
lel cuts are then made, with the spoil (overburden) deposited in the cut
just previously excavated. The final cut produces an open trench as deep
as the combined thickness of the overburden and the ore recovered,
bounded on one side by the last spoil bank and on the other by the undis-
turbed highwall. Such a strip-mined area may encompass several square
miles and will, prior to grading during the reclamation resemble a gigan-
tic washboard. Coal and Florida phosphate account for the major part of
the acreage disturbed by this method, but brown iron ore, some clays,
and other commodities are also mined in a similar manner.
Contour strip mining (Figure 6) is most commonly practiced where
deposits occur in rolling or mountainous country. Basically, this method
ORIGINAL GROUND
SURFACE
MINERAL SEAM r^=£^.r
Figure 5. Area surface mining method (U.S. Department of Interior, 1965).
12
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SURFACE MINING
I ^ MINERAL
SEAM
BACKFILLED BENCH ^
^ ^X -X - SPOILBANK +£.-__ s
,_ ORIGINAL GROUND SURFACE ~^-
•DIVERSION DITCH
SPOIL BANK
CUT
DRAINWAY
MINERA
SEAM -
BACKFILLED BENCH
- INL -i—
ORIGINAL GROUND SURFACE
—• '-----. OUTLET -^— - .. _
PIPE OR OTHER
DRAINAGE STRUCTURE
RIPRAP DITCH
STREAM
Figure 6. Contour strip mine after regrading (U.S. Department of Interior, 1965).
13
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MINING METHODS
consists of removing the overburden above the bed by starting at the out-
crop and proceeding along the hillside. After the deposit is exposed and
removed by this first cut, additional cuts are made until the ratio of over-
burden to product brings the operation to a halt. This type of mining
creates a shelf, or "bench, " on the hillside. On the inside it is bordered
by the highwall, which may range from a few to perhaps more than 100
feet in height, and on the opposite, or outer, side by a rim below which
there is frequently a precipitous downslope that has been covered by spoil
material cast down the hillside. Contour mining is practiced widely in
the coal fields of Appalachia and western phosphate mining regions be-
cause of the generally rugged topography.
Auger mining is usually associated with contour strip mining. In
coal fields, it is most commonly practiced to recover additional tonnages
after the coal-overburden ratio has become such as to render further
contour mining uneconomical. As the name implies, augering is a method
of producing coal by boring horizontally into the seam, much like the
carpenter bores a hole in wood. The coal is extracted in the same man-
ner that shavings are produced by the carpenter's bit. Cutting heads of
some coal augers are as large as seven feet in diameter. By adding
sections behind the cutting head, holes may be drilled in excess of 200
feet. As augering generally is conducted after the strip-mining phase
has been completed, little land disturbance can be directly attributed to
it. However, it may induce surface subsidence and complicate surface
and groundwater flow when underground workings are intersected.
Dredging operations utilize a suction apparatus or various mechani-
cal devices, such as ladder or chain buckets, clamshells, and draglines
mounted on floating barges. Dredges have been utilized extensively in
placer gold mining. Tailings piles from gold dredging operations usually
have a configuration that is similar to spoil piles left by area strip min-
ing for coal. Dredging is also used in the recovery of sand and gravel
14
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SOLUTION MINING
from stream beds and low-lying lands. In the sand and gravel industry
most of the dredged material is marketed, but in dredging for the higher
priced minerals virtually all of the mined material consists of waste
that is left at the mine site.
In hydraulic mining a powerful jet of water is employed to wash down
or erode a bank of earth or gravel that either is the overburden or con-
tains the desired ore. The ore-bearing material is fed into sluices or
other concentrating devices where the desired product is separated from
the tailings, or waste—by differences in specific gravity. Hydraulic min-
ing was extensively used in the past to produce gold and other precious
metals, but it is practiced only on a limited scale today.
SOLUTION MINING
Solution mining, as the term is used here, refers to the extraction
of minerals soluble in water or salt solutions by injecting the water
through wells or shafts into the deposit, then extracting the injected
water through the casing of the injection well or through separate extrac-
tion wells (Figure 7). Solution mining has been used or proposed for
common salt (NaCl), potash, borax, phosphate, and trona (Hunkin, 1971).
Sulfur is mined by the Frasch Process in which the sulfur is melted with
injected hot water and brought to the surface through wells (Figure 8).
About 57 percent of the 1968 production of salt and 76 percent of the sul-
fur was obtained by solution mining. Principal salt-producing States are
Louisiana, Texas, Ohio, New York, and Michigan. Louisiana and Texas
are the nation's primary sulfur-producing States.
Commercial salt deposits in Louisiana and Texas occur in the salt
domes that are present in the Gulf Coast geologic province of those States.
These salt domes are also important sources of solution-mined sulfur.
In other geographic areas of the United States, salt and the other minerals
listed above occur in bedded deposits.
15
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MINING METHODS
Figure 7. Single-well systems for solution mining of halite
(Jacoby, 1973).
Hydraulic fracturing is widely used to increase the permeability of
salt deposits and to develop communication between injection and produc-
tion wells. Controlling the location, direction, and extent of hydraulic
fractures is difficult because of mechanical problems and the anisotropic
nature of rock layers. Henderson (1963) lists the principal reasons for
failure of attempts to connect two wells by fracturing as:
1. A poor primary cement job of the well casing
2. A fracture in the crystalline structure of the salt which
causes the fluid to follow an indeterminant path
3. Natural vertical fractures, generally in the formation
immediately below the salt, allowing the fluid to escape
into a heavily fractured or permeable formation
4. The fracturing well being at a different geological depth
than the target well.
16
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SOLUTION MINING
AIR
SULFUR AND AIR
HOT WATER
MELTS SULFUR
SULFUR
BEARING
FORMATION
LIQUID SULFUR
FLOWS TO WELL
AND COLLECTS
AS A POOL
BARREN ROCK (ANHYDRITE)
_t:
t|.
T
rf.';--
rf-ROCK SALT
Figure 8. Operation of a sulfur well during solution mining of
sulfur by the Frasch Process (Donner and Wornat, 1973).
17
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MINING METHODS
Control of fracturing is difficult, yet is clearly essential if the tech-
nique is used in situations where highly mineralized fluids used for solu-
tion mining might inadvertantly be introduced into and damage the quality
of groundwater bodies.
Another significant problem in solution mining is the collapse of
solution-mined caverns. In 1971, the Michigan State Department of
Natural Resources issued an order restricting hydraulic mining of salt
at Grosse Isle following the development of two large sinkholes on prop-
erty owned by a salt company on an island in the Detroit River. The
caved areas, 100 to 200 feet in diameter and 30 to 40 feet deep, were
believed to have been caused by removal of salt from beds lying about
1, 100 feet beneath the surface. A study of the problem was planned by
State officials before deciding upon a course of action (MacMillan, 1973).
In many cases, caverns formed by solution mining are used for stor-
age of liquid petroleum gas, natural gas, and other hydrocarbons, storage
of radioactive wastes, and surge vessels for air compressed by electric
utilities during off-peak hours (Jacoby, 1972). In the development of
solution-mined caverns for storage purposes, and in solution mining of
minerals, there is often a need for disposal of waste brines. Many of
the industrial wastewater injection-wells inventoried by Warner (1972)
in Kansas, Texas, Michigan, and New York are for disposal of brines
produced by solution mining.
LEACHING
Leaching is the term applied to the selective dissolution of a mineral
from an ore using a solvent, such as sulfuric acid. Leaching methods
are dump, heap, in-place or in-situ, and vat leaching.
Some metallic minerals that have been recovered or considered for
recovery by leaching include copper, uranium, mercury, molybdenum,
silver, gold, aluminum, and zinc (Hunkin, 1971; Nichols and Peterson,
18
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LEACHING
1970; McKinney, 1973; and Sheffer and Lamar, 1968). Leaching has be-
come a very important method of extracting copper in the United States.
According to Pernichele (1973) about 20 percent of the domestically pro-
duced copper is obtained by dump and heap leaching. Because of eco-
nomic, environmental, and other reasons, in-situ leaching is receiving
increasing attention (Pernichele, 1973; Hunkin, 1971).
Choice of the leaching method depends upon the chemical and physical
characteristics of the specific material to be treated. The grade of the
ore, the solubility of the ore minerals, the amount of solvent-consuming
material in the host rock, the size of the operation, and the mode of oc-
currence of the ore-bearing minerals are some of the important factors
to be considered.
Dump leaching is used to extract copper from waste material pro-
duced during the large-scale open-pit mining of copper ore deposits.
Nearly all the copper-mining companies employ some form of leaching
for recovery of trace amounts of copper from the mine overburden or
waste. The mine waste dumps are made up of mine-run material with
no attempt to prepare the material as to size, type or elimination of
deleterious gangue minerals. In the majority of mining operations, the
waste is moved as rapidly and efficiently as possible with no considera-
tion for subsequent leaching of the copper.
Heap leaching is used for ores that are too low in grade to be pro-
cessed by conventional means or by vat leaching, and also for complex
ores that are not suitable for conventional processing. In heap leaching,
pads are prepared for the ore by clearing an area and emplacing a layer
of compacted clay, with a collection dam or reservoir at the topographi-
cally low end of the pad. Pads have been constructed with concrete,
asphalt, or plastic membranes, but according to Malouf (1973) these have
proven unsuitable because they are invariably ruptured by the weight of
the ore.
19
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MINING METHODS
Vat leaching of copper is used primarily for high-grade oxide or
mixed oxide-sulfide ores. Ore is crushed, screened, and placed in large
leaching tanks, where the leaching solutions are circulated through the
crushed ore.
In-situ leaching of copper ore has been practiced in the United States
since 1922 (Hardwick, 1967). All of the examples cited by Hardwick (1967)
of mines in which in-situ leaching had been used prior to 1967 are ones
in which extensive underground mining and block caving preceded the so-
lution mining. In such cases, the ore body is already broken and collapsed,
so that the leaching solutions have easy access to the ore-bearing rock
(Figure 9). In stiuations where mining has not been so extensive or where
there has been no previous mining and the ore occurs in relatively imper-
meable igneous and metamorphic rocks, fracturing may be with conven-
tional explosives as in the case of the Old Reliable copper mine (Malouf,
1973), by hydraulic fracturing (Pernichele, 1973), or possibly by nuclear
fracturing in the future (Hardwick, 1967). In-situ leaching of uranium in
a permeable sandstone ore body has been carried out, apparently without
any fracturing of the ore-bearing deposit (Anderson and Ritchie, 1968;
Sievert and others, 1970).
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^V;;;y:-:^|5*V^.|? DRILL ;,*
m^£jt*\f^ml*ir/z^ / U*""^..,. * r--r- 5
Figure 9. Flood-leaching mining system (Hardwick, 1967).
20
-------
WASTE DISPOSAL
IN-SITU COMBUSTION
In-situ combustion for secondary recovery of liquid hydrocarbons
has been practiced for some time, and the in-situ combustion of various
solid fossil fuels has been discussed and experimentation with it conducted
by industrial companies and the U. S. Bureau of Mines. However, the
technology has apparently not yet been developed to the extent that there
are any commercial operations of this type.
In the case of oil shale, a key problem is the creation of permeability
within the shale formation. Two major approaches are in early stages
of investigation. One approach proposes limited fracturing by conven-
tional means, the other proposes massive fracturing by a nuclear explo-
sion (Williams and others, 1969).
Figure 10 presents a design concept for in-situ retorting based on
contemporary petroleum technology (U.S. Department of Interior, 1973).
The essential steps include: (1) well drilling, (2) fracturing to permit
heat transfer and movement of liquids and gases, (3) application of heat,
and (4) recovery of products. The two Wyoming sites proposed for leas-
ing in the prototype oil shale program would be best mined by in-situ
methods (U.S. Department of Interior, 1973).
WASTE DISPOSAL
Solid Wastes
In the mining and processing of most minerals, some rock is mined
that is barren of the minerals that are being sought or contains the min-
erals but in concentrations too low to be economical. Waste rock or
low-grade ore that is not mixed with the ore-bearing rock may be imme-
diately discarded, but some waste rock is so intimately mixed with the
ore-bearing rock that it must be separated by some mechanical means
before it can be discarded, or perhaps it may be necessary to process
it metallurgically with the ore to achieve separation.
21
-------
NO
OIL AND GAS
AIR AND RECIRCULATED
GAS INJECTION
TEMPERATURE
/ PROFILE
z
o
o
o
Figure 10. SchemaHc representation of an in-situ retorting operation (U.S. Department of Interior, 1973).
-------
WASTE DISPOSAL
In any event, very large volumes of solid wastes result. These
wastes range in particle size from boulders to colloids. The larger
material may be conveyed to the disposal site by truck or conveyor belt.
Most material fine enough to be suspended in water is carried to the dis-
posal site in pipes or channels, where the solids are separated from the
liquid in tailings ponds. Some appreciation of the volume of solid wastes
produced can be obtained by realizing that the average grade of copper
ore mined in the United States is now about 0. 5 percent, so 99. 5 percent
of the rock mined is waste. It has been estimated that 1. 7 billion tons
of solid wastes were produced by the mining industry in 1971 and that 20
billion tons have been produced in the last 30 years (National Commission
on Materials Policy, 1973).
The wastes may be piled in open areas, in the heads of valleys, on
alluvial plains, or other locations, or they may be used to construct dams
across valleys. Mine wastes may also be used to backfill the worked-out
areas of underground mines to prevent collapse of the workings and sub-
sidence and to minimize the need for surface disposal.
Liquid Wastes
Liquid wastes produced in mining and mineral processing range
in character from high-quality unpolluted groundwater pumped to
dewater mines to the effluent from mineral preparation plants which
may contain acids, alkalis, heavy metals, radioactive elements, etc.
Unpolluted groundwater pumped during dewatering will usually be dis-
charged directly into a surface drainage system. Mine water polluted
with acid produced by pyrite oxidation or mill effluents has, in the past,
also been discharged into surface drainages or into holding ponds where
it eventually seeped into the subsurface or overflowed into surface
drainages. In some cases, physical and chemical changes that occur in
holding ponds are sufficient to produce an acceptable discharge; but, in
many cases, the effluent will require treatment before it can meet the
water quality requirements that have and will be imposed on operators.
23
-------
SECTION V
EXTENT OF MINING ACTIVITIES
A large part of American economic life is mirrored in the record of
materials production and population growth. The pattern of materials
use has changed dramatically over the past 70 years. The amount of
materials used has increased in both absolute and per capita terms.
Overall growth has been remarkably steady in spite of two world wars
and a world depression. Energy materials head the list of greatest
growth. No major raw material has become obsolete. A host of new
products are made today that were not conceived in 1900.
From 1900 to 1969, the U.S. population increased by 166 percent,
the GNP by almost 900 percent (in constant 1967 dollars), and total ma-
terials consumption by more than 400 percent (National Commission on
Materials Policy, 1973). Many of these materials have been obtained
by mining. Further, it is probable that the production of materials, in-
cluding mined products, will continue to increase in the future.
It is not possible to determine how many mines of all types have been
opened and their associated refuse and tailings disposal sites created in
the past. In a detailed study of the Appalachian coal-mining region, it
was found that at least 5, 570 sources of acid mine drainage existed, in-
cluding 405 associated with active coal mines, and 5,165 associated with
inactive or abandoned coal mines (Federal Water Pollution Control Ad-
ministration, 1969). The U. S. Department of the Interior (1965) estimated
that, in 1965, past surface mining had affected 3. 2 million acres of land
and that about 20, 000 active surface mines were disturbing in excess of
150, 000 acres annually. It has been estimated that more than 20,000
24
-------
EXTENT OF
MINING ACTIVITIES
prospect holes and mine and mill dumps exist in the State of Colorado
alone, most of them abandoned {Federal Water Pollution Control Admini-
stration, 1968).
According to the U.S. Department of the Interior (1972) there was
a total of 25, 148 active mines, quarries, pits, dredges, brine, well, and
other mineral-extractive operations in 1969. The largest numbers of
mines were in Pennsylvania (1,733), Kentucky (1, 576), West Virginia
(1,507), and California (1,380). There were 5, 168 active mineral prep-
aration plants. Information is available in publications such as that cited
above and from State agencies to permit fairly accurate determination of
the number, location, size, and nature of all existing mining operations
in the United States.
Future projections of the demand for minerals and mineral fuels are
available from many different sources. In particular, the 1973 report of
the National Commission on Materials Policy and the annual reports of
the Secretary of the Interior under the Mining and Minerals Policy Act
of 1970 (P. JL. 91-631} provide current information on this subject. Re-
gardless of the source of figures used, all estimates indicate a continu-
ously growing need for mineral commodities. In particular, the nation's
present and future dependency on mineral energy sources was brought
into focus during 1973 and 1974; but many knowledgable authorities have
warned of the danger of comparable problems with other minerals.
Thus, it seems inevitable that mining and related activities will not
only continue, but will increase. Also, newer mining technologies, such
as in-situ combustion and leaching will probably receive greater empha-
sis as lower grade and less accessible mineral deposits are exploited,
and mining will move into new geographic areas such as those where the
western coal fields and oil shale deposits occur.
25
-------
SECTION VI
MINING HYDROLOGY AND
GROUNDWATER POLLUTION
Most underground mines will in some way measurably interrupt the
existing hydrologic system at the location where they are developed.
In the case of an underground mine that reaches below the water table of
an unconfined aquifer or intersects a confined aquifer, groundwater will
have to be pumped to allow the mine to be worked, and pumping will have
to be continued as long as the mine is being operated. During this time,
the mine will be a sink, toward which groundwater will flow, and ground-
water levels will be lowered in the surrounding area (Figure 11). LeGrand
(1972) briefly outlined the physical effects of mining on groundwater sys-
tems, particularly in the case of underground mines.
Two well-known and widely discussed examples of the problem of
mine dewatering and the resultant effect of the dewatering on the hydro-
logic system of the surrounding area are the Hershey Valley, Pennsylvania
(Foose, 1953) and Friedensville, Pennsylvania (Childs, 1957). In the Her-
shey Valley, pumping of up to 6,500 gallons per minute was necessary to
dewater an underground limestone mine. This pumpage was sufficient to
lower the groundwater table drastically over an area of 10 square miles,
to dry up many springs and wells, and to cause about 100 new sink holes
to develop. At Friedensville, dewatering of a zinc mine caused numerous
springs and wells to dry up, and required the development of a pipeline
to supply water to residents of the affected area.
Dewatering of underground mines may also affect the quality of
groundwater. The most serious water quality problem associated with
past and present mining in the United States is the formation of acid mine
water. Acid mine water is formed when pyrite (FeS-) and perhaps other
26
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MINING HYDROLOGY AND
GROUNDWATER POLLUTION
PLAN VIEW
BOUNDARY OF LEASE
PRIVATE WELLS
MINE
a
WELLS
STREAM
PROFILE VIEW
WATER TABLE
\
AREA (a) UNWATERED WHEN SHAFT WAS 250 FEET DEEP
ADDITIONAL AREA {bl UNWATERED WHEN SHAFT WAS 550 FEET DEEP
ADDITIONAL AREA (c) UNWATERED WHEN SHAFT WAS 1200 FEET DEEP
Figure 11. Cone of depression resulting from mine dewatering (LeGrand, 1972).
sulfide minerals are exposed to the atmosphere as a result of the mining
operations.
Although the exact reaction process is still not fully understood, the
formation of acid mine water from pyrite is generally illustrated by the
equations shown below. The initial reaction that occurs when iron sulfide
minerals are exposed to air and water produces ferrous sulfate and sul-
furic acid.
2FeS
(pyrite)
ZFeSO,
'4 ' —2 — 4
(ferrous sulfate) (sulfuric acid)
27
-------
MINING HYDROLOGY AND
GROUNDWATER POLLUTION
Subsequent oxidation of ferrous sulfate produces ferric sulfate.
4FeSO. + 2H_SO + O_ *-2Fe0(SOJ. + 2H_O .
4 Z 4 Z 243 2
(ferric sulfate)
Depending on physical and chemical conditions, the reaction may then
proceed to form ferric hydroxide or basic ferric sulfate.
3 »- 2Fe(OH),
U -± J L. J
(ferric hydroxide)
and/or
-»- 2Fe(OH)(SO ) + H SO
(basic ferric sulfate)
Pyrite can also be oxidized by ferric iron as shown below.
+ 14Fe+3 + 8K,0 *- 15Fe+2 + 2SO/2 + 16H+
2 4
Regardless of the reaction mechanism, the oxidation of one molecular
weight of pyrite ultimately leads to the release of two molecular weights
of sulfuric acid (acidity).
Other constituents found in mine drainage are produced by secondary
reactions of sulfuric acid with minerals and organic compounds in the
mine and along the stream valleys. Such secondary reactions commonly
produce concentrations of aluminum, manganese, calcium, and sodium
in the drainage waters from coal mining areas. In metal mining areas,
other constituents such as copper, lead, zinc, nickel, silver, fluoride,
uranium, antimony, mercury, chromium, selenium, cadmium, and ar-
senic have been found in excessive concentrations. In fact, copper has
long been commercially extracted from natural mine waters; and, as has
been explained, leaching of copper from copper ore and waste rock using
sulfuric acid is an important mining method.
28
-------
MINING HYDROLOGY AND
GROUNDWATER POLLUTION
Articles by Emrich (1965), Emrich and Merritt (1969), Merritt and
Emrich (1970), Butcher and others (1967), Parizek (1971) and Parizek
and Tarr (1972) discuss the groundwater hydrology typical of many under-
ground coal mines in the Appalachian coal-mining area and also deal
specifically with groundwater pollution from underground coal mining in
that area or depict situations that could obviously result in groundwater
pollution.
Many of the underground coal mines in Appalachia are above-drainage
drift mines (Figure 1). In many if not all cases, the coal seam and the
overlying beds are saturated prior to mining. As a result of mining,
these strata are dewatered, either by gravity flow or pumping (Figure 8).
After the groundwater table has been lowered, the pyrite that was pre-
viously below the water table is exposed to oxygen in the air and oxidation
of the pyrite occurs. The sulfate and iron become soluble as a result of
the oxidation and are taken into solution by water percolating through the
partially saturated soil and rock above the mine. The acid water then
enters the mine workings and flows out by gravity, is pumped out, or
percolates through the mine floor and. enters the groundwater system
(Figures 12 and 13). The acid drainage that directly enters the ground-
water system through the mine floor, will, of course, act as a pollutant.
Water that flows or is pumped from mines first becomes part of the sur-
face water, but may enter the groundwater system by infiltration at some
point as shown in Figure 14. It was determined that, as of 1969, 10, 500
miles of Appalachian streams were significantly affected by coal-mine
drainage pollution, including entire drainage basins and several major
streams (Federal Water Pollution Control Administration, 1969). In a
U.S. Environmental Protection Agency sponsored survey of groundwater
pollution in the northeastern United States, four instances of groundwater
pollution from acid mine water have been identified in Maryland and 18 in
Pennsylvania (written communication, D.W. Miller, Geraghty and Miller,
29
-------
MINING HYDROLOGY AND
GROUNDWATER POLLUTION
GRAVITY
DRAINAGE
(a)
PUMPING REQUIRED
DURING MINING
LEAKAGE
AROUND SEAL
3:
; PARTIAL FLOODING
(b)
Figure 12. Drift mining of coal to provide free gravity drainage during mining (a) and
partial flooding of mine after sealing (b). In (c) coal is mined downdip and
requires pumping during mining but in (d) the mine floods completely when
abandoned (Parizek and Tarr, 1972).
(a)
. T. ri 1-. ,-» . .^. It __^ _^_
F.gure 13. Relationship of underground coal mines to groundwater flow systems before
mine sealing (a) and after sealing and flooding (b). In (b), a greater propor-
fion of mine drainage is diverted to the regional groundwater flow system
(Parizek and Tarr, 1972).
30
-------
^CONTAMINATED
HSURFACE WATER;?
o z
a G>
Figure 14. Diagram showing how contaminated water can be induced to flow from a surface source to
a well (Deutsch, 1963).
00
1=0
c -<
I-
Z D
-------
GROUNDWATER POLLUTION
Inc. ). These are undoubtedly only examples of the effect of acid mine
water on groundwater in that area.
Deutsch (1963) gave an example of the pollution of a shallow gravel
aquifer by infiltration of water pumped to the surface from an underground
iron mine. The contaminants were dissolved solids and hardness.
One method of controlling the production of acid water from aban-
doned above-drainage drift mines is sealing off the mine in an attempt
to flood the mine and thus stop the oxidation of pyrite. Figure 13 shows
how such sealing may increase the amount of acid water entering the
groundwater system. The principles discussed above with reference to
above-drainage coal mines also will apply to metal mines that occur in
a similar topographic and hydrologic setting and where oxidizable sulfide
minerals are present. Many metal mines in the western United States
are in this category.
Acid water is also formed in underground mines that are below the
level of the local drainage system. Mines of this type must be continuously
pumped during their operation to allow them to be worked. The mine thus
becomes the center of a cone of depression in the groundwater table (Fig-
ure 11). Pyrite in the rocks that are drained during the operation of the
mine is thus subject to oxidation and the water being pumped from the
mine may be acid. As long as the mine is being operated and the water
discharged at the surface, groundwater pollution would occur principally
from infiltration of the pumped water back into the groundwater system.
However, when the mine is abandoned, the workings will fill with water,
which will take the already oxidized minerals into solution. This polluted
water will then enter the flowing groundwater system. No detailed study
of such a situation was found in the literature, but the water in many aban-
doned deep coal mines is known to be acid and it would be expected that
water in some flooded underground metal mines might also be acid and
contain higher than usual concentrations of the metals that occur in the
32
-------
MINING HYDROLOGY AND
GROUNDWATER POLLUTION
local rocks. Proctor and others (1973) have found unusually high concen-
trations of zinc and other metals in shallow ground-water in the Joplin,
Missouri, area and they believe that it is probable the shallow aquifers
are connected with abandoned mines in that area or that groundwater per-
colates through brecciated and mineralized areas associated with mines
resulting in the high metal contents.
In addition to the types of groundwater pollution mentioned above,
the pumping of underground mines may result in the upward flow of saline
groundwater in the vicinity of the mine, thus inducing saline water intru-
sion, as shown in Figure 15. The hazard of this happening may be partic-
ularly great in some areas of Appalachia where saline water occurs at
depths of only 100 to 300 feet (Wilmoth, 1971). This type of groundwater
quality deterioration is anticipated as a potential problem in the mining
of oil shale at the two proposed prototype Colorado tracts (U.S. Department
XS. PUMPING WELL
Figure 15. Diagram showing how a pumping well can cause a fresh-water
aquifer to be contaminated by saline water from underlying
rocks (Deutsch, 1963).
33
-------
MINING HYDROLOGY AND
GROUNDWATER POLLUTION
of the Interior, 1973). The hydrologic situation in the Piceance Basin
oil shale area is shown in Figure 16. Interaquifer flow, leading to ground-
water contamination, could also be induced by unplugged exploratory drill
holes or even abandoned oil and gas wells that may intersect mines con-
taining contaminated water (Emrich and Merritt, 1969; Merritt and Emrich,
1970; Thompson, 1972). One method that is suggested for the disposal of
the large volume of saline water that would eventually be pumped from the
underground oil shale mines in Colorado is reinjection into a slightly
deeper aquifer (U.S. Department of the Interior, 1973). A result of such
extensive injection would be to increase upward flow of saline water from
the injection zone into the shallower fresh-water aquifers.
The same chemical reactions that create acid mine water during under-
ground coal mining occur in the spoils from area-strip and contour-strip
coal mines. Rainwater that infiltrates into acid-bearing spoils dissolves the
sulfate, iron, and other minerals, then continues downward into the ground-
water system or until it contacts an impervious layer where it will migrate
laterally and emerge as seepage at the perimeter of the spoil pile. Ground-
water that flows laterally into and through strip-mine spoils may also be-
come mineralized. Probably the most detailed study of the influences of
coal strip mining on groundwater and surface water quality was that per-
formed by the U.S. Geological Survey in the Beaver Creek basin, Kentucky
(Collier and others, 1970), during which it was found that mining has sig-
nificantly increased the acidity and mineralization of groundwater and sur-
face water. Emrich and Merritt (1969) reported that polluted drainage
from coal strip mines in the Thorns Run drainage basin, Pennsylvania,
entered deeper aquifers along joints, fractures, and especially through
abandoned oil and gas wells.
Corbett (1965) and Cederstrom (1971) have pointed out that the spoils
t
from area-strip mining have a large capacity for retention of water and
may have the beneficial effect of reducing runoff and increasing the base
34
-------
WEST
8000
7000
6000'
5000'
4000'
3000'
PICEANCE CREEK
ALLUVIUM
EVACUATION CREEK MEMBER
PARACHUTE CREEK MEMBER
MAHOGANY ZONE
DIRECTION OF — —
WATER MOVEMENT
CREEK MEMBER
SALINE WATEF
DOUGLAS
CREEK MEMBER
GARDEN GULCH MEMBER
WASATCH FORMATION
EAST
8000'
7000'
6000'
- 5000"
-4000'
3000'
VERTICAL EXAGGERATION X 20
DATUM IS MEAN SEA LEVEL
SAND AND GRAVEL SANDSTONE OR
OR CONGLOMERATE SILTSTONE
MARLSTONE MA RLSTONE; CONTAINS HIGH RESISTIVITY
SHALE AND KEROGEN, ZONE
AND SALINE MINERALS
IN STRUCTURALLY
LOWEST PART OF
BASIN
o z
n O
¥. ?°
z?
Qo
Figure 16. Diagrammatic section across the Piceance Basin (after Coffin, and others, 1971).
-------
MINING HYDROLOGY AND
GROUNDWATER POLLUTION
flow of streams, However, if the spoils contain appreciable soluble min-
erals, the water that they store may be of poor quality and contribute to
surface water and groundwater pollution.
Considerable concern has been expressed about the possible effect
of area-strip mining of coal in Wyoming, Montana, North Dakota, and
other western States on the groundwater resources of those States (The
Ground Water Newsletter, 1973). In a recent environmental impact state-
ment for the Peabody Coal Company Big Sky Mine, southeastern Montana
(U.S. Geological Survey, 1973), it was concluded that the mine would in-
evitably destroy parts of certain aquifers, interrupt the local groundwater
flow pattern, and probably lower the quality of shallow groundwater in the
immediate vicinity. The one mine is projected to disturb only about 4, 300
acres, but surface mining of western coals has only recently become of
significant magnitude and the potential for growth is very great. It has
been estimated that the amount of coal mined in the western States in 1985
will be more than 10 times that mined in 1970 (Coal Age, 1973). The
western States contain about 60 percent of the nation's strippable coal re-
serves, about two-thirds of which is in the three States mentioned above.
Strip mining of minerals other than coal could be expected to have
similar adverse effects on the quality of groundwater resources where
circumstances are conducive. Clay mining in Pennsylvania creates many
of the same problems as coal mining. Phosphate mining and milling have
recently been found to be the source of extensive radiochemical pollution
of groundwater in Florida (U.S. Environmental Protection Agency, 1974;
Rouse, 1974). Uranium mining in the western States would be expected
to have had some adverse effects on groundwater quality through leaching
of the spoils, but no documentation of such problems was located.
36
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MINING HYDROLOGY AND
GROUNDWATER POLLUTION
In some cases it is necessary to dewater strip mines and open-pit
mines. Extensive pumping of groundwater at a surface mine of any kind
could lead to vertical intrusion of saline water or even lateral intrusion
of sea water if the mine were very near the sea. Deutsch (1963) reported
a case where dewatering of a limestone quarry appeared to have acceler-
ated the normal upward encroachment of mineralized water and contributed
to pollution of the shallow fresh-water zone (Figure 17). A situation where
the potential exists for both vertical and lateral intrusion as a result of
pumping 60 mgd from a phosphate mine in eastern North Carolina is de-
scribed by Peek (1969) and Hird (1971). According to Peek, water levels
in the affected aquifers were rapidly lowered to below sea level in an area
of about 800 square miles and to more than 100 feet below sea level in the
immediate vicinity of the mine. However, Hird reported that no water
quality change had yet been observed in monitor -wells in 1970.
I 1
ORIGINAL FRESHWATER TABI f 1
I
REMNANT OF FRESHWATER ZONE
ZONE OF SALINE WATER INTRUSION
ORIGINAL FRESH SALINE WATER INTERFACE
Figure 17. Diagram showing migration of saline water caused by dewatering in a
fresh-water aquifer overlying a saline-water aquifer (Deufsch, 1968).
37
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MINING HYDROLOGY AND
GROUNDWATER POLLUTION
Auger mining is generally carried out in conjunction with contour-
strip mining of coal, as has been described. Probably the greatest effect
of augering on -water quality results from the connections between strip
mines and underground mines that are caused by auger holes that are
driven from the highwall of the contour mine into the workings of under-
ground mines. Such holes allow water from strip mines to flow into
underground workings and vice versa. This situation complicates the
hydrology and makes some in-situ control methods impractical.
Dredging of sand and gravel and placer minerals would tend to dis-
rupt the alluvial aquifers that are being mined, but it is not obvious that
any chemical pollution of the aquifers would result from dredging. Hy-
draulic mining is little practiced today, except for a few gold mines in
Alaska; and, while such mining may greatly affect the quality of adjacent
streams, there should not be much effect on groundwater quality.
Disposal of solid wastes into abandoned quarries, gravel pits, and
strip mines has long been practiced. Although such practice is not part
of surface mining itself, it is closely enough related to be worthy of men-
tion. The potential for groundwater pollution from disposal of waste into
the cavities left by surface mining is obvious. Emrich and Landon (1971)
investigated the effects of disposal of urban solid wastes in coal strip
mines on groundwater quality and found that in four of the five sites that
were studied groundwater pollution had occurred or would be expected to
occur.
Strata in which solution mining is practiced (Figures 7 and 8) inher-
ently contain highly mineralized water, because the salt or other minerals
being mined are water soluble. The potential for groundwater pollution
from solution mining would be from interaquifer flow of the saline water
as a result of:
1. Escape of saline water through a well bore into a fresh-water
aquifer because of insufficient casing, by corrosion, or by
other failure of the well casing
38
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MINING HYDROLOGY AND
GROUNDWATER POLLUTION
2. Vertical escape of saline water, outside of the well casing,
into a fresh-water aquifer
3. Vertical escape of saline water through aquicludes that are
leaky because of high primary permeability, solution channels,
joints, faults, or induced fractures
4. Vertical movement of saline water through other nearby deep
wells that are improperly cemented or plugged, or that have
insufficient or corroded casing.
Fracturing of aquicludes could be caused by the high injection pressures
Used to fracture the salt or other minerals being mined or by subsidence
over mined cavities. When surface collapse results from subsidence, the
Potential for groundwater contamination is increased because polluted
surface water can be funneled into aquifers.
Leakage of ponds used to hold brine solutions is also a potential pollu-
tion mechanism. Although there are a large number of solution mining
operations in the United States, and there is obviously a significant possi-
bility of groundwater contamination from such mining, no published exam-
Pies were found.
Groundwater pollution from in-situ dump- and heap-leaching of metal-
lic ores could occur as a result of loss of the leaching agent into the ground-
water system (Figure 9). As Rouse (1974)(a) points out, there is an inherent,
risk of spills and leakage during the handling and storage of large volumes
of leach solution and recovered pregnant liquor. He further comments that
^is risk is greatly enhanced by less than adequate construction methods
that are all too common around leach-mining operations. Cederstrom (1971)
Mentions that contamination of groundwater supplied has occurred as a con-
sequence of leaching of pyritic copper ores. He cites an example of pollu-
tion of an alluvial aquifer by waste leach water discharged into the stream
course that recharged the aquifer.
39
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MINING HYDROLOGY AND
GROUNDWATER POLLUTION
On the positive side, Longwell (1974) reports that no evidence of
lateral migration of leach solutions has been observed in conduction with
in-situ leaching at the Old Reliable copper mine, Arizona, after one year
of operation. Similarly, Pizarro and others (1974) report no evidence of
groundwater pollution in monitor wells at Carlin Gold Mining Company's
Carlin, Nevada heap-leaching facility after several years of operation.
Sites for the disposal of solid and liquid wastes from mining and
mineral processing are potential groundwater pollution sources much the
same as sanitary landfills and lagoons for other liquid wastes. In addi-
tion, mine refuse, mill tailings, or coal preparation plant wastes are
frequently used to construct dams and the reservoirs formed by these
dams may be used to contain pumped mine water or wastewater from
mineral processing.
Piles of waste from coal mining and refuse from coal preparation
plants are frequent sources of acid water, since this material often con-
tains very high concentrations of pyrite. Wastes from many metal mines
and their associated mills are also acid producing and the drainage may
contain many other minerals, as has previously been mentioned. Mink,
Williams, and Wallace (1971) describe the pollution of an alluvial aquifer
in the Canyon Creek basin in the Coeur d'Alene mining district of Idaho
as a result of previous mining. The pollutants are cadmium, copper,
lead, and zinc leached from the tailings left by the concentrating of ore
from metal mines. Mink and others (1971), Galbraith and others (1972),
Williams and Wallace (1973), and Sceva (1973) reported further on ground-
water pollution from mining in the Coeur d'Alene mining district of Idaho,
much of which is caused by tailings piles. This example is probably typi-
cal of what would be found in other mining districts in western States, if
they were examined. The potential for groundwater pollution from a pro-
posed tailings dam and settling pond for the Homestake gold mine is briefly
described in the environmental impact statement for that project (U.S.
Environmental Protection Agency, 1972).
40
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MINING HYDROLOGY AND
GROUNDWATER POLLUTION
Groundwater pollution from leaching of uranium mill tailings is another
problem that is known to exist, but for which the magnitude has not been
defined. The Federal Water Pollution Control Admininstration (1966) re-
ported that "industry-owned observation wells in the near vicinity of tail-
ings and uranium mills have been reported to indicate radiation levels well
above background. " The FWPCA report cited one example of a contami-
nated domestic well and speculated that other groundwater pollution could
result in the future by recharge of alluvial aquifers from polluted streams.
At the time that the report was written ten operating and seven inactive
uranium mills and concentrating plants were located in the Colorado River
basin and only one had attempted to prevent downward percolation of water
by placing a bentonite base beneath the tailings pile of the plant.
There are no commercial in-situ combination mining projects (Figure
10) at the present time. Some information on the effect of in-situ mining
of oil shale on groundwater quality has been obtained by the U.S. Bureau
of Mines in pilot-scale tests in Wyoming. At one site, the dissolved solids
content in water taken from wells approximately 200 feet from the burned
zone increased from about 500 ppm at the beginning of the experiment to
20,000 ppm within two months after the experiment (U.S. Department of
the Interior, 1973).
The volume of the spent oil shale that is produced during retorting is
greater than the volume of the original shale as extracted from underground.
Disposal of the spent shale is a major problem. Possibilities for disposal
include backfilling mines or depositing the spent shale in the deep gullies
and canyons that are often characteristic of the regions in which oil shale
is found. Water percolating through the spent shale in surface disposal
sites might be intercepted, although this is a major undertaking. It would
be quite difficult to prevent groundwater pollution from backfilled under-
ground mines. The potential for water pollution by circulation of water
through spent shale was evaluated by Colorado State University (1971).
41
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MINING HYDROLOGY AND
GROUNDWATER POLLUTION
The study showed that substantial quantities of soluble salts, particularly
sodium, calcium, magnesium, and sulfate are present in spent shales and
that concentrations of these ions in water percolated through spent shale
exceeded 100,000 mg/liter in the initial samples of leachate. These ex-
periments are not sufficient to determine what the magnitude of the prob-
lem from a full-scale operation would be; however, it is apparent that
groundwater contamination might occur from leaching of organic and in-
organic minerals in spent shale.
Water pumped from underground mines and released into tailings
ponds may increase greatly in dissolved solids in arid areas as a result
of evaporation. This water then becomes a pollutant, if it infiltrates back
into the groundwater system.
An unusual mechanism for water pollution from tailings piles is that
which may occur when fine tailings are distributed by wind and carried
into surface waters or leached by rainwater. The potential for pollution
from this source was recognized in the previously discussed studies of
uranium tailings and pollution from windblown tailings has been observed
in the Coeur d'Alene mining district (Sceva, 1973). An example of this
type of groundwater pollution is shown in Figure 18.
42
-------
WINDBLOWN CHROME-LADEN DUST
CO
TO MUNICIPAL
i-1 i -HI
Figure 18. Diagram showing possible mode of entry of windblown wastes into an aquifer (Deutsch, 1963).
-------
SECTION VII
METHODS FOR CONTROL AND PREVENTION
OF GROUNDWATER POLLUTION
A recent comprehensive U.S. Environmental Protection Agency pub-
lication (U.S. Environmental Protection Agency, 1973) provides a sum-
mary of currently available processes, procedures, and methods for the
control of water pollution from mining activities. The methods listed
for underground mines include controlled mining procedures, water infil-
tration control, wastewater control, mine sealing, and treatment. Tech-
niques for surface mines are similar, but also include erosion control,
regrading, and revegetation. All techniques have potential for reducing
both surface and groundwater pollution, but their discussion is beyond
the scope of this report, except where the technique may directly relate
to groundwater pollution and its monitoring. The various techniques may
be classified as either at-source or treatment methods. The at-source
control methods deal with the mine site and its hydrology and are of inter-
est here.
As is noted in the introductory chapters of the sections of the EPA
report dealing with control of water pollution from both underground and
surface mining, effective mine site studies and preplanning of the entire
mining operation from the opening to the closing of a mine are fundamental
to effective pollution control. Site hydrology is important, because water
passing through the mine site and its vicinity provides the mechanism for
transfer of pollutants into the groundwater system. The details of such
site studies could be discussed here or in the monitoring section, but the
latter has been selected because of the emphasis of this report. The dis-
cussion of at-source control techniques that follows has been modified
from that presented in the EPA publication. Original references are not
cited here, but may be obtained from the EPA report.
44
-------
UNDERGROUND MINES
UNDERGROUND MINES
Preplanned Flooding
As previously explained, the principal cause of polluted mine water
is the oxidation of sulfide minerals exposed during mining. Flooding of
a mine upon completion of mining will greatly reduce further oxidation.
The most effective method of achieving flooding is by mining downdip and
leaving a barrier at the outcrop, so that flooding will occur naturally
(Figure 19). Although flooding will control further oxidation of sulfide
minerals, it may contribute to groundwater pollution in some cases by
dissolving previously oxidized minerals and by increasing the rate of flow
into groundwater aquifers (Figure 13).
Roof Fracture Control
Most of the water entering many underground mines passes vertically
through the mine roof from overlying strata. The original source of this
water is infiltrating rainfall. Collapse of a mine roof is sometimes re-
sponsible for increased vertical flow, particularly in coal mines. Roof
collapse causes widespread fracturing in the strata around a mine roof,
and subsequent joint separation far above the roof. These opened joints
can tap overlying perched aquifers and provide flow paths to the mine.
Roof collapse in shallow mines will often cause surface subsidence. Sub-
sidence fissures collect and then funnel surface runoff directly to the mine.
Roof collapse and fracturing of overlying strata can be reduced by
using the roof support techniques discussed in Section IV, Mining Methods.
In review, these are:
1. Methods of natural roof support, such as the room and pillar
system
2. Artificial support methods, such as square-set stoping
3. Combinations of 1 and 2.
45
-------
GROUNDWATER POLLUTION
CONTROL AND PREVENTION
MINERAL
BARRIER
PUMPING REQUIRED
DURING MINING
UNDERGROUND
MINE
GROUNDWATER
LEVEL
GROUND
SURFACE
DOWNDIP MINE-DURING MINING
GROUNDWATER
LEVEL
INUNDATED
UNDERGROUND
MINE
MINERAL
BARRIER
GROUND
SURFACE
DOWNDIP MINE-AFTER MINING
Figure 19. Preplanned flooding of underground drift mines (U.S. Environmental
Protection Agency, 1973).
In order for this technique to be useful in pollution control, the result-
ant decrease in flow must not be accompanied by a proportionate increase
in pollution concentration. If such a tradeoff should occur, the pollution
load could remain essentially the same. This tradeoff is not an entirely
unlikely possibility.
46
-------
UNDERGROUND MINES
Coal mine drainage will be used as an example of how this could occur.
Coal mine drainage pollutants result from the oxidation of pyrite. Oxygen
and water are required for this oxidation reaction in a nonflooded mine.
The relative humidity in an underground coal mine is usually at or near
saturation (100 percent relative humidity). Mine walls are normally damp.
Water required for the pollution-forming reaction is almost always avail-
able. Flushing of the oxidation sites is not even required. Salts resulting
from oxidation are hygroscopic, meaning that they will draw water from
the atmospheric humidity. The salts will seep downward from the accum-
ulated humidity, exposing the reaction sites to further oxidation. The point
of this discussion is that the availability of oxygen is the oxidation rate
controlling factor, and the amount of water flowing through the mine does
not control the oxidation rate. Pollution production may be constant within
the mine regardless of the flow of water through the mine. Decreasing
flow may result in increased pollution concentrations.
Therefore it is possible that decreasing mine drainage could have little
or no effect in controlling pollution. Decreased flow may result in decreased
water pollution if the amount of drainage is reduced sufficiently to prevent
pollution transportation from the mine. In this case, decreases in water
pollution coming out to the surface could also result in increases in ground-
water pollution.
Increasing Surface Runoff
With objectives similar to those in roof fracture control, water infil-
tration can be decreased by increasing surface water runoff. This technique
involves elimination of depressions and grading the surface to increase
water velocities. Subsidence depressions often collect and convey large
quantities of surface water to underground mines. The amount of water
collected depends on size of drainage area tributary to the depression,
and annual rainfall and runoff rate. Subsidence holes in stream channels
can cause entire streams to enter underlying underground mines. Uneven
47
-------
GROUNDWATER POLLUTION
CONTROL AND PREVENTION
surfaces caused by agricultural, logging or other surface activities can
cause increased infiltration.
Surface runoff can be increased by grading an overlying area to a
smoother, better draining configuration. Surface depressions can be filled
in and leveled with clay. Stream channels can be flurried, reconstructed
with impermeable liners, or diverted around water loss areas. Channel
stability under increased flows must be assured.
As with roof fracture control, the overall effect of increased surface
runoff should be appraised to insure that the objective of decreased pollu-
tion loads is achieved and that groundwater pollution is not accelerated.
Regrading Surface Mines
Surface mines are often responsible for collecting and conveying large
quantities of surface water to adjacent or underlying underground mines.
Nonregraded surface mines often collect water in an open pit where no sur-
face exit point is available. Many abandoned underground mine outcrop
areas have been contour stripped. These surface mines often intercepted
underground mine workings, providing a direct hydrologic connection.
The surface mine does not have to intercept underground mine workings
in order to increase infiltration. Surface mines on the updip side of under-
ground mines collect water and allow it to enter a permeable coal seam.
It then flows along the coal seam to underground mines. Overlying surface
mines that collect and entrap water can also be significant sources of'infil-
tration. These surface mines facilitate entry of surface runoff to the
groundwater system, which eventually works its way into an underground
mine. Regrading techniques are discussed under control techniques for
surface mines in the EPA report.
Sealing Boreholes and Fracture Zones
Boreholes and fracture zones act as water conduits to underground
mines. They are usually vertical, or near vertical, and tap overlying
aquifers. They collect and transport groundwater.
48
-------
UNDERGROUND MINES
Boreholes are commonly present around underground mines and usu-
ally remain from earlier mineral exploration efforts. These boreholes
can be located and plugged to prevent passage of water. Concrete can be
inserted hydraulically to form a seal. Boreholes can be easily sealed
from below in an active underground mine. Difficulty can be encountered
if sealing has to be performed from the surface. Abandoned holes are
often difficult to locate on the surface, and many times they will be blocked
by debris.
Fracture zones are often major conduits of water. They increase
vertical movement of water and can cause large lateral movements. Frac-
ture zones are usually vertically oriented planar type features. Their lo-
cation can be plotted by experienced personnel using aerial photography.
Permeability of these zones can be reduced by drilling and grouting. Holes
are drilled into the zone and grout is inserted hydraulically. Care must
be taken to ensure that the boreholes are located in the fracture zone at
the point of grouting. There are various types of grout available; however,
concrete is commonly used.
Interception of Aquifers
This technique takes advantage of the natural geologic and hydrologic
systems surrounding a mined area. It involves use of boreholes, casing,
and pumps to transfer water from one point to another in order to reduce
water flow into an underground mine. The techniques are theoretical and
will require development and demonstration to establish feasibility.
A complete hydrogeologic site evaluation of a mined area to determine
aquifer characteristics and water flow systems is required prior to imple-
mentation. Most underground mines receive water from overlying aquifers.
Several techniques can be employed to tap these aquifers and reduce the
amount of water entering a mine. Overlying aquifers can be drilled and
the water pumped to the surface (Figure 20). Boreholes can also be drilled
49
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GROUNDWATER POLLUTION
CONTROL AND PREVENTION
WELL
POINTS
GROUND
SURFACE
ORIGINAL
GROUNDWATER
LEVEL
Figure 20. Interception of mine water by pumping of overlying aquifers (U.S.
Environmental Protection Agency, 1973).
through aquiferst passing through an underground mine and into underlying
aquifers (Figure 21-a). The boreholes must be cased through the mined
zone (it collects water from the overlying aquifer, passes it through the
mine zone for discharge to an underlying aquifer). The underlying aquifer
must be capable of accepting the anticipated flow.
A variation on this technique is to drill holes into the underground
mine, casing and grouting the borehole through the zone forming the roof.
The boreholes are then connected by pipes and the water carried outside
the mine. The uncased or perforated-casing portion of the borehole col-
lects water from overlying aquifers and passes it into the piping system
for conveyance out of the mine, never contacting pollution-forming materials
(Figure 21-b).
Boreholes, pumps and piping systems can also be used to convey acid
mine drainage to a nearby alkaline aquifer, or alkaline underground mine,
to encourage mixing, neutralization and settling of precipitates.
50
-------
UNDERGROUND MINES
GRAVITY
WELLS "\
— X^:---x-r?:r--^
lavi'fri rix;-:: 'xxx-x-x . i
1
ll
[
___-.-— -ft
\ ; '•; '%':.;;iJ
IIIIIllllllll
ill--: ""•••:..• 4
?FREE WATER
i; SURFACE
'••••:• MJiLLov::...x.:.x- f, j
j_xx::xxx.:- xxx, .xx.j
^CASING 1
|::.vx xx:x: ,",'• ...' ..;.; M:V.;.' u.'.J
1
( DEEP
Xx>x:x,,-xx,:x-x.,.,xxx,J
i lIHIf1'! i
1 J
GRAVITY
X^J/VELLS \
£Q— ^
txv,,xxxxx,,,.x'':-xxx :•:«;
t— CASING— H
Ix-x :•:•:• .•.x.xo.-'-xix1'----- .•••.••• 1
1
AQUIFER
lilililll
i
GROUNDWATER
r- LEVEL
:^^b>-^^ SURFACE
f5^ SOURCE BED"~X S>T\
:;x CONFINING BED KSxxl^
UNDERGROUND MINE
CONFINING BED;:A:-.:;,x,,,:
FREE WATER
k^ f SURFACE
''"" 1 m:^M§ :'^mijiiji \
GRAVITY
WELL
FREE WATER
GRAVITY SURFACES
GROUND
SURFACE
MINE
DRAINAGE
SEEPAGE
FACE
UNDERGROUND MINE
INTERCEPTION OF AQUIFERS
Figure 21. Interception of mine water by gravity wells (U.S. Environmental Protec-
tion Agency, 1973).
51
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GROUNDWATER POLLUTION
CONTROL AND PREVENTION
Mine Sealing
Mine sealing is used to promote mine flooding as was previously dis-
cussed under preplanned flooding. Mine sealing for purposes of inundation
involved construction of a physical barrier in a mine opening to prevent
passage of water. A barrier must be designed to withstand the maximum
expected pressure (head) of water that will be exerted against it. Sealing
underground mines is somewhat analogous to creating a surface water im-
poundment: a major portion of the dam structure would already be in place
and the seal merely closes the opening. Engineering considerations are
also similar to these for surface impoundment design. The entire dam
structure must be capable of withstanding exerted pressure, and leakage
rates must be determined. Underground mine seals have seldom been
successful due to lack of consideration of leakage rates and weak points.
Seals can be designed to withstand a large amount of pressure, but the
seal is only a small part of the impoundment structure. The perimeter
of the mine forms most of the impoundment, and often it is not capable
of withstanding any significant amount of pressure.
As with preplanned flooding, there is potential for increased ground-
water pollution, and such operations should be carefully monitored to
determine their overall effect.
SURFACE MINING
The general methods of controlling water pollution from surface min-
ing were previously listed. Within the general methods, a large number
of variations are discussed in the EPA publication, of which only selected
ones can be reviewed here.
Controlled Mining Procedures
Ten controlled surface mining procedures are discussed in the EPA
report. As an example, one of these, the use of mineral or low-wall bar-
riers will be included.
52
-------
SURFACE MINING
Mineral or low-wall barriers are portions of the mineral and/or
overburden that are left in place during contour strip mining (Figure 22).
The barrier is intended to retain surface water in the mine during mining
and retain groundwater in the base of the regraded spoil bank after recla-
mation. If pollution-forming materials are buried at the base of the spoils
they can thus be covered with water and oxidation of pyrite retarded. A
possible negative effect of such barriers would be to increase infiltration
of polluted water into the groundwater system.
Water Infiltration Control
Chemical pollution of surface water and groundwater that results from
surface mining is caused by leaching of the pollutants from the spoil mate-
rial. Much of the leaching occurs during infiltration of water into the spoils,
Controlling water infiltration from, rainfall and subsurface sources
can be accomplished by placing impervious barriers on or around the waste
material, establishing vegetative cover, or constructing underdrains. Im-
pervious barriers, constructed of clay, concrete, asphalt, latex, plastic,
or formed by special processes such as carbonate bonding, can prevent
water from reaching the waste material. Figure 23 shows the reduction
of surface water infiltration by implacement of impermeable material.
. ORIGINAL GROUND
SURFACE
STOCKPILED SPOIL
MATERIAL
PIT FLOOR
Figure 22. Impoundment of water in a contour strip mine by use of a low-wall
barrier (U.S. Environmental Protection Agency, 1973).
53
-------
GROUNDWATER POLLUTION
CONTROL AND PREVENTION
ORIGINAL GROUND
SURFACE
IMPERMEABLE
MATERIAL
CLEAN SPOIL
Figure 23. Control of infiltration by implacement of impermeable material (U.S.
Environmental Protection Agency, 1973).
Pollutants may also be leached by groundwater flowing laterally through
spoils. Such pollution can be controlled by placement of impermeable bar-
riers to restrict groundwater flow. As an example, an impermeable bar-
rier can be placed against the highwall of a surface mine to prevent flow
of water from an adjacent underground mine through the spoils of a regraded
strip mine (Figure 24).
Handling of Pollution-Forming Materials
Pollution-forming materials originated by mining or mineral prepara-
tion include all solid wastes that contribute to water quality degradation as
surface or groundwater percolates through or flows over them.
One method of handling such pollution-forming materials is to remove
them to a more suitable location such as is shown in Figure 25. Another
possible handling method with multiple objectives is backfilling of under-
ground mines. In this method, the pollution-forming materials are re-
moved to an isolated location, the use of surface space is minimized, and
support for the mined-out area is provided. Backfilling of underground
54
-------
SURFACE MINING
• ORIGINAL GROUND SURFACE
BACKFILLED GROUND SURFACE
Figure 24. Control of lateral flow through strip mine spoils by implacement of
impermeable material (U.S. Enfironmental Protection Agency, 1973).
ORIGINAL GROUND SURFACE
BACKFILLED GROUND SURFACE
IMPERMEABLE MATERIAL
0,9 meter (3') MINIMUM
POLLUTION-FORMING
MATERIAL
GRADED MATERIAL
0.9 meter (3') MINIMUM
Figure 25. Relocation of pollution-forming material in the spoil bank of a contour
strip mine (U.S. Environmental Protection Agency, 1973).
55
-------
GROUNDWATER POLLUTION
CONTROL AND PREVENTION
oil shale mines with spent oil shale is contemplated as a possible method
of disposal of those wastes, which will be a major problem as that industry
develops. A possible problem that could result from backfilling of under-
ground mines would be pollution of groundwater during its percolation
through the backfilled areas. An excellent example of this pollution mech-
anism was described by Trexler and others (1974) in their discussion of
the Bunker Hill Mine in Idaho.
Wastewater Control
Once mine or mill water becomes polluted, it can only be treated or
handled in some way to minimize its polluting effect on the water resource
as a whole. Wastewater control methods include recycling and reuse,
holding and evaporation, holding and controlled discharge, and spray irri-
gation. All of these techniques may pose some hazard to groundwater if
improperly practiced, since they either involve impounding of the waste-
water with an inherent potential for loss by seepage or spreading on the
surface with its potential for introduction of pollutants by infiltration.
Subsurface injection, rerouting, and mineral recovery are also discussed
under the heading of wastewater control in the EPA publication.
56
-------
SECTION VIII
MONITORING
Monitoring of water quality might be defined as a scientifically de-
signed program of continuing surveillance; including direct sampling and
remote quality measurements, inventory of existing and potential causes
of change, and analysis of the cause of past quality changes and prediction
of the nature of future quality changes.
Unfortunately, monitoring of groundwater is often thought of only in
the context of sampling of wells and springs. Such sampling is a dominant
or sole practice in most surveillance programs; however, sampling can
be minimized and perhaps even eliminated in some cases by thorough in-
ventory of possible causes and prediction of anticipated quality changes.
For example, a situation in which direct sampling could be eliminated
would be one where a planned activity is analyzed, major groundwater
pollution predicted, and the planned activity is cancelled because of the
unacceptable level of predicted pollution. An alternative outcome if the
planned activity were implemented after analysis of the anticipated effects
would be that the location and number of sampling points and the quality
parameters analyzed would be minimized by anticipating the location of
the source(s) and nature of pollution and by making predictions of rates
and direction of pollution travel. The entire process described is thus
considered to be monitoring.
EVALUATION OF PROPOSED MINING ACTIVITIES
An important key to monitoring the effect of any mining activity on
groundwater quality is the development of an adequate understanding of
the local geology, hydrology, and geochemistry. Gathering the necessary
57
-------
MONITORING
geohydrologic information should be a normal activity during the explora-
tory steps prior to the initiation of mining.
Experience obtained from evaluating the water pollution potential of
surface and underground coal mines during their permitting is valuable
in establishing the detailed list of required information. The State of
Pennsylvania has developed a manual for this purpose, the Mine Drainage
Manual (Pennsylvania Department of Health, 1966). Below is a modified
list of some of the information requested in applications for mine drainage
permits in Pennsylvania.
1. Type of mine.
2. Geologic column, indicating seams to be mined and amount
and location of coal to be extracted from each seam.
3. Maps showing:
a. geology of mine area
b. topography and surface drainage
c. boundaries of mining operation
d. points at which drainage is likely to exit from mine
e. locations of interconnected deep and strip mines, extent
of workings, existing mine water impoundments, and
present mine water discharge points.
4. Strike and dip (pitch) of coal seam(s).
5. Mining method and proposed development plan.
6. Mine drainage:
a. anticipated amount and chemical character
b. will drainag-e discharge by natural flow or will it be pumped?
c. how will drainage be handled in the mine?
d. details of any proposed treatment including final quality of
treated effluent.
7. Proposed mine waste-handling plans.
58
-------
EVALUATION OF PROPOSED
MINING ACTIVITIES
8. Grcmndwater:
a. water-bearing strata in the area, configuration of water
table(s), and quality of water(s)
b. location, discharge, and quality of water for any springs
in area
c. location, depth, construction, and use of all wells in the
area to be mined and of any proposed wells.
9. Plans for mine abandonment.
When the coal mine is a new one, an estimate of the quality of drainage
from the mine may be made by examining existing mines in the area. For
cases where no other coal mines are present in the immediate area, Em-
rich (1966) and Renton and others (1973) have suggested laboratory proce-
dures for determining the acid-producing potential of coals, and the Uni-
versity of West Virginia (1971) recommended field and laboratory methods
for recognizing the pollution-forming potential of coal strip mine overburden
prior to mining.
The procedures described in the references given above provide for
prediction of the acid-forming potential of coal and overburden materials,
but the means of relating this to the amount of surface or groundwater
pollution from, a mining operation is not developed.
If, for example, it were desired to predict the extent of groundwater
pollution from surface coal mining as a result of pyrite oxidation, the
variables that would have to be considered are:
1. The amount and distribution of oxidizable sulfide minerals
2. The kinetics of pyrite oxidation
3. The rate of transport of the oxidation products to the ground-
water system and their concentration in the transporting water
4. The mechanics of mixing and transport of pollutants within the
groundwater system.
59
-------
MONITORING
In spite of the obvious complexity of the problem, a group of research-
ers at Ohio State University has published the description of a model for
the prediction of the discharge rates and acid loads from a single under-
ground coal mine (Morth and others, 1972) and the same group is presently
working on a model for an entire small drainage basin, including surface
and underground mines. If a model could be developed during the planning
for a new mine that would yield reasonable values of the probable extent
of pollution that would occur, the prediction could be used as one basis for
determining whether or not the mine should be opened and what monitoring
should be done if the mine is opened. The present models do not yet ap-
pear to have this capability.
Hunkin (1971) compared the engineering of an in-situ uranium mining
operation with the secondary recovery of oil by waterflooding and suggested
that the feasibility of an in-situ leaching project requires a three-stage
evaluation. The environmental considerations in the first stage include:
1. An ore body confined by natural or artificial means in such a
way that dilution or fluid losses maybe restricted to an accept-
able level
2. An aquifer with low groundwater velocity that is not used for
water supply.
If these and other criteria in the first-stage evaluation are satisfied,
then Hunkin recommends the following for the second stage:
1. Regional hydrology survey including seasonal variation, water
usage, and regional groundwater flow.
2. Local hydrology survey, say for 10,000-ft. radius around pro-
posed site. Groundwater contours, terrain, geological features
(in particular, faults, dikes, and sills which may indicate local
variation in permeability), and surface drainage features must
be included.
60
-------
EVALUATION OF PROPOSED
MINING ACTIVITIES
3. Geophysical surveys to substantiate hydrological and geological
interpretations. Minimum requirements are gamma log, self-
potential, and resistivity logs, spaced with due regard to hetero-
geneity of formation.
4. Detailed water sampling program covering all seasons to deter-
mine quality of water in adjacent aquifers, streams,lakes and
springs. This is essential in order to establish contamination
levels existing prior to commencement of operations and to set
standards for a continuous monitoring system during later
operations.
The third stage is detailed site investigation, including core drilling and
injection and bail testing of boreholes.
Rouse (1974) states that requirements for monitoring of an in-situ
leaching operation are very similar to those for wastewater injection
wells. He suggests the Environmental Protection Agency's recommended
data requirements for environmental .evaluation of subsurface injection
wells as a basis for evaluating leaching operations.
In cases where the magnitude of the mining operation and the environ-
mental hazard warrant the effort, it may be desirable to develop a mathe-
matical model of the groundwater system in the area to determine as ac-
curately as possible the rate and direction of flow and concentration of
pollutants in the system (Tinlin and others, 1973). Modeling of this type
has been used, for example, to predict the rate and direction of spread of
radioactive wastes at the National Reactor Testing Station, Idaho (Robert-
son and Barraclough, 1973), and for estimating the effects of dewatering
an oil-shale mine on groundwater in western Colorado (Coffin and Bredehoeft,
1969). Such models can, to a certain extent, take into account dispersion,
radioactive decay, chemical reaction, adsorption, ion exchange, and den-
sity stratification of pollutants as they flow through the aquifer. Mathema-
tical models may, as they are developed and verified, serve to reduce the
61
-------
MONITORING
number of sampling points, help to determine how frequently samples
should be taken, and indicate constituents which should be considered in
chemical and biological analyses.
MONITORING DURING OPERATION
Some means of surveillance of groundwater quality during the opera-
tion of a mine and its auxiliary facilities are water sampling, measurement
of groundwater levels, geophysical measurements, remote sensing, mon-
itoring of storage tanks and pipeline, monitoring of solid and liquid waste-
disposal areas, and maintenance of material balances.
Water Sampling
SAMPLING POINTS.
1. Monitor wells —These may be specially constructed or may be
existing wells converted to use as monitor wells. A monitor
well may be pumped or unpumped. An unpumped well samples
only the water that passes directly through the well bore. A
pumped monitor well produces an integrated sample from an
area whose size depends on the local geohydrology and the rate
of pumping.
2. Water supplies —Samples of groundwater pumped for water sup-
ply can be periodically taken and analyzed to detect quality
changes. Such samples are representative of the well or wells
in the system and the area or areas of influence.
3. Springs—Since springs are outlet areas for groundwater, sam-
ples taken from them are similar to ones from pumped wells,
in that they reflect the quality of water within an area of influence.
4. Streams —Because many streams derive most of their flow from
groundwater drainage for a substantial part of each year, sam-
ples from gaining streams can be used to measure groundwater
quality. Similarly, samples from losing streams can yield
62
-------
MONITORING DURING OPERATION
information on pollution entering the groundwater from surface
water sources. A gaining stream might be thought of as rep-
resenting the composite quality of a number of springs.
LOCATION OF SAMPLING POINTS. As LeGrand (1968) has stated,
haphazard plans for the location of monitoring sites are almost certain
to result in excessive cost and to fail in their objective. He further points
out that such sites must be located on the basis of the hydrogeologic frame-
work, and provides some useful general guidelines for planning their loca-
tion. Rouse (1974) also comments on the need for designing an observation
well system based on site geology and hydrology, rather than routinely
placing such wells in a circle around the operation to be monitored. The
concept of using modeling methods for optimizing the location of monitor-
ing points has previously been discussed.
FREQUENCY OF SAMPLING. Under natural conditions the quality
of groundwater will typically change imperceptibly with time. Rates of
change are related to rates of flow, which in turn are governed by the hydro-
geologic situation. Some groundwater basins unaffected by man show an-
nual fluctuations in quality produced by seasonal variations in recharge,
level changes, and discharge.
The influences of man can and do cause significant changes in ground-
water quality. Two common effects are an increase in amplitude-of annual
changes in quality and a progressive deterioration in quality over a period
of many years.
The frequency of monitoring groundwater quality depends upon its
sensitivity to natural and manmade influences. For effluent wastes to the
ground which are subject to rapid changes in composition, continuous,
daily or weekly sampling may be appropriate. To characterize changes
which might occur annually in groundwater, a bimonthly or quarterly fre-
quency should be adequate. In general where prior background informa-
tion is insufficient to define periodic changes, a surveillance program
63
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MONITORING
should include at least two years of observation at this frequency. There-
after, the frequency can be reduced to monitor long-term rates of change
of various constituents, but probably not less than semiannually.
Monitoring near or downstream from a known pollution source may
require a frequency of the order of semimonthly, monthly, or bimonthly.
Monitoring of groundwater flowing toward wells or being pumped from
wells should be conducted perhaps semiannually, while background quality
control sites for groundwater basins may be as infrequent as annually.
Wherever and whenever a pollution hazard develops, such as a toxic con-
stituent affecting an underground water supply source, the frequency of
monitoring must be increased in accordance with the importance or serious-
ness of the situation.
POLLUTANTS MONITORED. Groundwater quality monitoring should
focus on specific pollutants because of their hazard, persistence, concen-
tration, ease of identification, or other characteristic features. In the
case of most mining activities, the specific pollutants that may be present
can be identified through knowledge of the source. Many of the pollutants
that will be found associated with particular types of mining activities have
been discussed in Section VI, Mining Hydrology and Groundwater
Pollution.
Groundwater Levels
Although measurement of groundwater levels does not provide quality
data directly, it can yield valuable indirect information. From a map of
water-level contours, the groundwater flow pattern of a region can be de-
fined. This will show the areas of groundwater recharge and their relation
to possible pollution sources. Changes with time of flow patterns due to
mining activities may be apparent so that the influence of pollution sources
as well as the location of polluted groundwater areas may be shown by
such maps.
64
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MONITORING DURING OPERATION
Geophysical Measurements
Geophysical measurements made in bore holes or on the ground sur-
face can provide valuable supplementary information in a monitoring pro-
gram. A wide variety of bore hole logging methods have been developed.
Keys and MacCary (1971) provide an extensive discussion of the use of
bore-hole geophysics in water-resource investigations.
Bore-hole geophysical devices may be designed to examine only the
fluids in the bore hole or to examine a volume of the aquifer around the
bore hole. Two fluid properties that are directly measured in the bore
hole are temperature and conductivity. Two aquifer properties that are
commonly measured are conductivity (resistivity) and natural radioactivity.
The conductivity and radioactivity of the aquifer water contributes to the
overall reading, and changes in the conductivity or radioactivity of the
water can thus be detected, even though the instruments are viewing a
section of the aquifer rather than the water alone.
Of the surface geophysical methods, electrical resistivity surveying
is the most useful for groundwater quality studies. Many types of pollu-
tants will increase the conductivity of groundwater and, under favorable
circumstances, such changes may be detected by resistivity surveying.
Merkel (1972) describes the use of electrical resistivity surveys to delineate
groundwater pollution from acid mine drainage. A number of other pub-
lications discuss the use of electrical resistivity to detect groundwater
pollution from other sources, principally sanitary landfills. Barr (1973)
reported on the feasibility of using seismic reflection for monitoring the
distribution of wastes in the vicinity of industrial injection wells. Because
of the small contrasts in seismic reflectivity of wastewater as compared
with formation water that will exist in most cases of groundwater pollution,
seismic techniques probably offer very limited monitoring potential.
65
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MONITORING
Remote Sensing
Remote sensing is the technology of remotely collecting and interpret-
ing data generated by electromagnetic energy from the earth's surface
and near surface. This definition includes conventional black and white
photography as well as the many newer methods that utilize other parts
of the electromagnetic specturm. Barr and James (1973) summarized
many of the uses of remote sensing including aerial monitoring of surface-
water quality. Monitoring of groundwater quality will probably be, in
most cases, indirect. In an example of the use of remote sensing for
mining problems, Ahmad (1973) described the use of satellite imagery
for study of strip-mined areas in Ohio. Remote sensing has been widely
used for agricultural studies and has been found useful for detection of
drainage and salinity problems (Meyers and others, 1963). This suggests
the use of remote sensing for indirectly inferring groundwater quality
problems based on soil conditions and on the response of vegetation to
changes in groundwater quality.
Monitoring of Storage Tanks and Pipelines
Storage tanks and pipelines associated with mining operations are
potential pollution sources and should be routinely inspected for leaks.
Pressure testing of tanks and pipelines would be an additional monitoring
method.
Monitoring of Solid and Liquid Waste Disposal Areas
Some examples of groundwater pollution problems associated with
the solid and liquid waste-disposal areas of mining operations have been
mentioned previously. Such areas should be designed to prevent water
pollution to begin with; but nevertheless, waste-disposal sites require
periodic inspection. For example, the lining of a waste storage pond or
the dike around a solid waste storage area could fail, thus releasing pol-
luted water to the environment.
66
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POST-OPERATIONAL MONITORING
Maintenance of Material Balances
In mining by leaching, chemical solvents are introduced into mines,
ore heaps, and mine dumps, as has been previously discussed. The
maintenance of an accurate material balance of introduced versus recov-
ered chemicals would provide a means of quantitatively determining the
amount of pollutants lost to the environment. The'detection of such losses
might also point to the existence of groundwater pollution before it could
be detected by other monitoring means. Material balances could also be
used for tailings ponds and evaporation basins to detect seepage losses.
POST-OPERATIONAL MONITORING
One characteristic of mining operations that distinguishes them from
many other industrial operations is the fact that some mines and waste
disposal areas will continue to be pollution sources long after the mines
and processing plants have closed. In fact, some will be pollution sources
indefinitely; that is, for geologic time. Sources of this type will obviously
require a monitoring philosophy different from that applied to sources
with finite lives. The range of possible schemes is great; but, in general,
the procedure would be to identify the source, to predict the rate of pro-
duction and distribution to pollutants, and then to periodically verify the
predictions. Such a procedure would provide continually updated informa-
tion on the location and intensity of pollution for use in groundwater
management.
67
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SECTION IX
LAWS AND REGULATIONS
There are a variety of different statutory means by which the States
and the Federal government can control water pollution from mining
activities. Water resources are directly protected by water pollution
control laws. In addition, there are provisions in a variety of other
laws, such as surface mine reclamation laws that may contribute to
water quality protection.
All States and the Federal government have water pollution control
laws that can be used directly, in one way or another, to control water
pollution from mines and mineral preparation plants. However, major
differences between mines and the usual industrial plants exist which re-
quire special consideration. Such differences include the fact that, for
effective pollution control, planning must often begin during the location
and design of the mine. Another important difference is the fact that
pollution may continue after abandonment of a mine. Only two States,
Pennsylvania and West Virginia, are known to formally recognize the
need for advance planning by requiring a permit be obtained prior to the
initiation of underground mining. In most other cases, it would only be
necessary for a mining company to obtain a permit when it became appar-
ent that there was a polluted discharge. Also, the requirement for a per-
mit before opening of an underground mine allows an opportunity for de-
nial of a permit if it appears impossible to effectively control water
pollution after abandonment by some at-source technique such as flooding.
Control of water pollution from mining on Federal land can be effected
through the State, directly by the Federal agency having jurisdiction, or
both. However, in the case of mines developed under the general mining
68
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LAWS AND REGULATIONS
law of 1872 there is probably no way of influencing the mining process or
requiring site restoration upon abandonment.
The main concern of surface mine reclamation laws is not water pol-
lution control and the enforcement agencies are not viewed as water pol-
lution control agencies. However, an important secondary consideration
in such laws, whether expressed or implied, is water pollution control.
At least 22 States have reclamation laws, including all of the major coal-
producing States. In many cases, the laws or the regulations developed
to complement them require a complete mining and reclamation plan to
be specified prior to issuance of a permit. In some cases it is possible
for a State to deny a permit if the environmental effects of mining are
judged to be too great. A Federal surface mining law was recommended
in 1965 (U.S. Department of the Interior, 1965), but as of the date of this
report such a law has not yet been passed. In the meantime, surface
mining on Federal land is subject to regulation except for mining done on
claims acquired under the general mining law of 1872, which has no pro-
visions for environmental control.
The National Environmental Policy Act of 1969 has proven to be a
very important means of identifying the potential environmental impact
of proposed mining operations on Federal land. When such impacts are
identified, then it is possible for the agency with authority to specify the
necessary controls for minimizing those impacts as a provision of the
lease. Several examples of such impact statements are included in the
reference list. Unfortunately, mining claims developed under the general
mining law of 1872 are not subject to the provisions of the National Envi-
ronmental Policy Act.
69
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SECTION X
REFERENCES
Ahmad, M. U. , "Mapping of Spoil Banks Using ERTS-A Pictures, " Proc.
Symposium on Significant Results Obtained from ERTS-1, NASA/
Goddard Space Flight Center, Greenbelt, Maryland, 1973.
Anderson, J. S. and M. I. Ritchie, "Solution Mining of Uranium, " Mining
Congress Jour. , pp. 20-26, January 1968.
Barr, D.J., and W. P. James, Application of Remote Sensing in Civil
Engineering, Am. Soc. of Civil Engrs. Environmental Engineering
Meeting, Oct. 29-Nov. 1, 1973, New York, N. Y., Meeting Preprint
2072, 30 pp., 1973.
Barr, F. J. , "Feasibility of a Seismic Reflection Monitoring System for
Underground Waste-Material Injection Sites, " Symposium on Under-
ground Waste Management and Artificial Recharge, J. Braunstein,
ed. , Am. Assoc. Petroleum Geologists, Tulsa, Oklahoma, pp. 207-
218, 1973.
Cederstrom, D. J., "Hydrologic Effects of Strip Mining West of Appalachia, "
Mining Congress Jour., Vol. 57, No. 3, pp. 46-50, 1971.
Childs, M.S. , "Geology and Development at Friedensville, Pa. , " Mining
Engineering, pp. 56-60, January 1957.
Coal Age, "Western Coal . . . Important Element in the National Energy
Outlook/1 Vol. 78, No. 5, pp. 57-66, 1973.
Coffin, D. L. , andJ.D. Bredehoeft, Digital Computer Modeling for Esti-
mating Mine-Drainage Problems, Piceance Creek Basin, Northwestern^
Colorado, U.S. Geological Survey Open File Report, 1969.
Coffin, D. L., and others, Geohydrology of the Piceance Creek Structural
Basin Between the White and Colorado Rivers, Northestern Colorado,
U.S. Geological Survey Hydrologic Investigations Atlas HA-370, 1971.
Collier, C.R. , R.J. Pickering, andJ.J. Musser, eds., Influences of
Strip Mining on the Hydrologic Environment of Parts of Beaver Creek
Basin, Kentucky, 1955-66, U.S. Geological Survey Prof. Paper 427-C,
80 pp. , 1970.
Colorado State University, Water Pollution Potential of Spent Oil Shale
Residues, U.S. Environmental Protection Agency Water Pollution
Control Research Series 14030 EDB 12/71, 116 pp., 1971.
70
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REFERENCES
Corbett, P.M., Water Supplied by Goal Surface Mines, Pike County.
Indiana, Indiana University Water Resources Research Center Report
of Investigations No. 1, 67 pp., 1965.
Deutsch, M., Ground Water Contamination and Legal Controls in Michi-
gan, U.S. Geological Survey Water Supply Paper 1691, 1963.
Donner, W.S. , and R. O. Wornat, "Mining Through Boreholes- Frasch
Sulfur Mining System," Mining Engineering Handbook, Cummins
and Given, eds. , Am. Inst. of Mining, Met., and Petr. Engrs. ,
New York, N. Y. , pp. 21-60 to 21-67, 1973.
Butcher, R. R. , and others, "Mine Drainage Part II: The Hydrogeologic
Setting, " Mineral Industries, Vol. 36, No. 4, Pennsylvania State
University, pp. 1-7, 1967.
Emrich, Grover H. , The Effects of Coal Mining on Ground Water, Am.
Institute of Mining Engineers Preprint 65-F-311, Am. Inst. Mining
Engineers Meeting, Phoenix, Arizona, 11 pp., 1965.
Emrich, G.H. , Tests for Evaluating the Quality of Mine Drainage Char-
acteristics of Coal Seams, Pennsylvania Department of Health, Divi-
sion of Sanitary Engineering, Technical Bull. No. 2, 1966.
Emrich, G.H. , and G. L. Merritt, "Effects of Mine Drainage on Ground-
water, " G_roundwater, Vol. 7, No. 3, May-June, pp. 27-32, 1969.
Emrich, G.H. , and R. A. Landon, Investigation of the Effects of Sanitary
Landfills in Coal Strip Mines on Ground Water Quality, Pennsylvania
Department of Environmental Resources, Bureau of Water Quality
Management, Pub. No. 30, 39pp., 1971.
Engineering and Mining Journal, "Rancher's Big Blast Shatters Copper
Ore Body for In-Situ Leaching, " Vol. 173, No. 4, pp. 98-100, 1972.
Federal Water Pollution Control Administration, Disposition and Control
of Uranium Mill Tailings Piles in the Colorado River Basin, U.S.
Department of Health, Education and Welfare, FWPCA Region 8,
Denver, Colorado, 36 pp. and appendices, 1966.
Federal Water Pollution Control Administration, Mining Evaluation Study.
South Platte River Basin. Colorado, U.S. Department of the Interior,
FWPCA, South Platte River Basin Project Denver, Colorado, 1968.
Federal Water Pollution Control Administration, Stream Pollution by
Coal Mine Drainage in Appalachia, FWPCA, Cincinnati, Ohio, 1969.
Foose, R. M. , "Ground-Water Behavior in the Hershey Valley, Pennsyl-
vania, " j3jan^_GepJ^J>pj=,.^ Vol. 64, pp. 623-646, June 1953.
Galbraith, J. H. , and others, "Migration and Leaching of Metals from
Old Mine Tailings Deposits, " Ground Water, Vol. 10, No. 3, pp. 33-
44, 1972.
71
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REFERENCES
Gordon, D. L. , and F. H. Dorheim, Criteria for the Use of Abandoned
Limestone and Gypsum Quarries for Sanitary Landfill Sites in Iowa,
Am. Inst. Mining Engrs., Soc. Mining Engr. Preprint No. 74-H-4,
1974.
Hardwick, W. R. , Fracturing a Deposit with Nuclear Explosives and Re-
covering Copper by the In-Situ Leaching Method, U.S. Bureau of
Mines Report of Investigations 6996, 1967.
Henderson, J. K, "Well Construction; Possible Causes of Failure and
Remedial Measures, " Symposium on Sact, A.C. Bersticker and
others, eds., 1961, Northern Ohio Geological Society, Inc., Cleve-
land, Ohio, pp. 555-562, 1963.
Hird, J. M. , "Control of Artesian Ground Water in Strip Mining Phosphate
Ores, Eastern North Carolina, " Trans. Am. Sci. Mining and Engi-
neers, Vol. 250, pp. 149-156, June 1971.
Hunkin, G.G. » A Review of In-Situ Leaching, Am. Inst. of Mining Engi-
neers, Society of Mining Engineers Preprint No. 71-AS-88, 27 pp.,
1971.
Jacoby, Charles, "Cavity Utilization, " Trans. Am. Inst; Mining Engrs. ,
Vol. 252, No. 2, pp. 143-146, June 1972.
Jacoby, C.H. , "Solution Mining of Halite through Boreholes, " Mining
Engineering Handbook, I. A. Given, ed. , Am. Inst. Mining, Met. ,
and Petr. Engrs., New York, N. Y. , pp. 21-49 to 21-55, 1973.
Keys, W.S., and L. M. MacCary, "Application of Borehole Geophysics
to Water Resource Investigations, " U.S. Geological Survey, Tech-
niques of Water-Resource Investigation, Book 2, Chap. El, 126 pp.
1971.
LeGrand, H. E., "Monitoring of Changes in Quality of Ground Water, "
Ground Water, Vol. 6, No. 3, pp. 14-18, 1968.
LeGrand, H. E., "Overview of Problems of Mine Hydrology, " Am. Insti-
tute of Mining Engineers Transactions, Vol. 25, pp. 362-365, Decem-
ber 1972.
Lewis, R. M. , and G. B. Clark, Elements of Mining, 3rd Ed. , John Wiley,
New York, 1964.
Longwell, R. L. , "In Place Leaching of a Mixed Copper Ore Body, "
Solution Mining Symposium, F.F. Apian and others, eds., Am.
Inst. of Mining, Metallurgical, and Petroleum Engineers, Inc. ,
New York, N. Y., pp. 233-242, 1974.
MacMillan, R. T. , "Salt, " Minerals Yearbook 1971, Vol. 1. Metals,
Minerals, and Fuels, U.S. Government Printing Office, Washington,
B.C., pp. 1031-1041, 1973.
72
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REFERENCES
Malouf, E. E. , "Leaching, " Mining Engineering Handbook, I. A.
Given, ed., Am. Inst. Mining, Met. , and Petr. Engrs. , New York,
N. Y., pp. 21-70 to 21-78, 1973.
McKinney, W. A. , "Solution Mining, " Mining Engineering, Vol. 25, No. 2,
pp. 67-68, 1973.
Merkel, R. H. , "The Use of Resistivity Techniques to Delineate Acid
Mine Drainage irx Ground Water, " Ground Water, Vol. 10, No. 5,
pp. 38-42, 1972.
Merritt, G.L. , and G. H. Emrich, "The Need for Hydrogeologic Evalu-
ation in a Mine Drainage Abatement Program: A Case Study—Thorns
Run, Clarion County, Pennsylvania, " Proc. 3rd Symposium>on Coal
Mine Drainage Research. Bituminous Coal Research, Inc., Monroe-
ville, Pennsylvania, pp. 56-82, 1970.
Meyers, V.I. , and others, "Photogrammetry for Detailed Detection of
Drainage and Salinity Problems, " Trans. Am. Soc. of Agricultural
Engrs., Vol. 11, No. 4, pp. 332-334, 1963.
Mink, L.L., and others, Effect of Industrial and Domestic Effluents on
the Water Quality of the Coeur d'Alene River Basin, Idaho Bureau of
Mines and Geology Pamphlet 149, Moscow, Idaho, 95 pp. , 1971.
Mink, L.L., R. E. Williams, and A. T. Wallace, "Effect of Early Day
Mining Operation on Present Day Water Quality, " Proc. National
Ground Water Quality Symposium, U.S. Environmental Protection
Agency, Water Pollution Control Research Series 16060 GRB 08/71,
pp. 111-120, 1971.
Morth, A. H. , and others, Pyritic Systems; A Mathematical Model, U.S.
Environmental Protection Agency, EPA-R2-72-002, 171 pp., Novem-
ber 1972.
National Commission on Materials Policy, Material Needs and the Envi-
ronment Today and Tomorrow, U.S. Government Printing Office,
Washington, D. C. , 1973.
Nichols, I. L. , and LeRoy Peterson, Leaching Gold-Bearing Mill Tailings
from Mercur, Utah, U.S. Bureau of Mines Report of Investigations
7395, 10 pp., 1970.
Parizek, R. R., Prevention of Coal Mine Drainage Formation by Wall
Dewatering, Special Report SR-82, Coal Research Section, The
Pennsylvania State University, 73 pp., 1971.
Parizek, R. R., and E.G. Tarr, "Mine Drainage Pollution Prevention and
Abatement Using Hydrogeological and Geochemical Systems," Fourth
Symposium on Coal Mine Drainage Research, Bituminous Coal Re-
search, Monroeville, Pennsylvania, pp. 56-82, 1972.
73
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REFERENCES
Peek, H. M., "Effects of Large-Scale Mining Withdrawals of Groundwater, "
Ground Water. Vol. 7, No. 4, pp. 12-20, 1969.
Pennsylvania Department of Health, Mine Drainage Manual, Pennsylvania
Department of Health, Division of Sanitary Engineering Publication
No. 12, 1966.
Pernichele, A.D., "Geohydrology, " Mining Engineering, Vol. 25, No. 2,
pp. 67-68, 1973.
Pizarro, Ramon, and others, "Heap Leaching Practice at the Carlin Gold
Mining Co. , Carlin, Nevada, " Solution Mining Symposium, F. F.
Apian, and others, eds. , Am. Inst. of Mining, Met., and Petr. Engr. ,
New York, N.Y., pp. 253-267, 1974.
Proctor, P. D. , G. Kisvarsanyi, E. Garrison, and A. Williams, Water
Quality as Related to Possible Heavy Metal Additions on Surface and
Ground Water in the Springfield and Joplin Areas, Missouri, Water
Resources Research Center, University of Missouri—Rolla, Rolla
Missouri, Office of Water Resources Research Project B-054-Mo.,
56 pp. , April 3, 1973.
Renton, J. J. , R. V. Hildago, and D. L. Steib, Relative Ac id-Producing
Potential of Coal, West Virginia Geological and Economic Survey,
Environmental Geology Bull. No. 11, 1973.
Robertson, J. B. , andJ.T. Barraclough, "Radioactive and Chemical-
Waste Transport in Groundwater at National Reactor Testing Station:
20 Year Case History and Digital Model," Underground Waste Manage-
ment and Artificial Recharge, Vol. 1, Am. Assoc. of Petroleum
Geologists, Tulsa, Oklahoma, pp. 291-322, 1973.
Rouse, J. V. "Environmental Aspects of In-Situ Mining and Dump Leaching, "
Proc. Solution Mining Symposium, F. F. Apian, and others, eds.,
The American Institute of Mining, Metallurgical, and Petroleum En-
gineers, Inc., New York, N. Y. , pp. 3-14, 1974.
Rouse, J. V. , "Radiochemical Pollution from. Phosphate Rock Mining and
Milling" (abstract), Program of National Symposium on Water Re-
sources Problems Related to Mining, American Water Resources
Association and Colorado School of Mines, Golden, Colorado, July
1-2, 1974(a).
Sceva, J.E., Water Quality Considerations for the Metal Mining Industry
in the Pacific Northwest, U.S. Environmental Protection Agency
Report No. Region X-3, Seattle, Washington, 1973.
Sheffer, H. W. , and G. E. LaMar, Copper Leaching Practices in the
United States, U.S. Bureau of Mines Information Circular 8341,
57 pp. , 1968.
74
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REFERENCES
Sievert, J.A. , and others, In-Situ Leaching of Uranium, Am. Inst. Mining
Engrs. Preprint No. 70-AS-334, 16pp., 1970.
The Ground Water Newsletter, Vol. 2, No. 20, p. 6, October 30, Water
Information Center, Port Washington, New York, 1973.
Thompson, D. R. , "Complex Ground-Water and Mine-Drainage Problems
from a Bituminous Coal Mine in Western Pennsylvania, " Bull. Assoc.
of Engineering Geologists, Vol. 9, No. 4, pp. 335-346, 1972.
Trexler, B.D. , and others, "The Hydrology of an Acid Mine Drainage
Problem" (abstract), Program of National Symposium on Water Re-
sources Related to Mining, American Water Resources Association
and Colorado School of Mines, Golden, Colorado, July 1-2, 1974.
Tinlin, R. M. , C.F. Meyer, andD.C. Kleinecke, Monitoring Groundwater
Quality, General Electric-TEMPO, Report P-639 presented at the
Annual Fall Meeting Am. Inst. Mining Engineers, Sept. 17-22, 1973,
Pittsburgh, Pennsylvania, 11 pp., 1973.
U.S. Department of the Interior, Surface Mining and Our Environment,
U.S. Government Printing Office, Washington, D. C. 1965.
U.S. Department of the Interior, Minerals Yearbook 1970, Vol. 2, Area
Reports, U.S. Government Printing Office, Washington, D. C. , 1972.
U. S. Department of the Interior, Final Environmental Statement for the
Prototype Oil Shale Leasing Program, U. S. Department of the Interior,
6 vols. , U.S. Government Printing Office, Washington, D. C. , 1973.
U.S. Environmental Protection Agency, Final Environmental Statement
Lead-Deadwood Sanitary District No. 1, South Dakota, Project No.
WPC SD-200, U.S. EPA Region 8, Denver, Colorado, 1972.
U.S. Environmental Protection Agency, Processes, Procedures, and
Methods to Control Pollution from Mining Activities, U. S. EPA
Publication EPA-430/9-73-011, 390pp., 1973.
U. S. Environmental Protection Agency, Reconnaissance Study of Radio-
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76 GPO 692-026/67
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. RPPORT NO
-JPA 680/4-74-003
3. RECIPIENT'S ACCESSION-NO.
^ TITLE AND SUBTITLE
RATIONALE AND METHODOLOGY FOR MONITORING GROUNDWATER
POLLUTED BY MINING ACTIVITIES
5, REPORT DATE
June 1974
6. PERFORMING ORGANIZATION CODE
• AUTHOR(S)
Don L. Warner (Consultant)
8. PERFORMING ORGANIZATION REPORT NO
GE74TMP-22
9. PERFORMING ORGANIZATION NAME AND ADDRESS
General Electric-TEMPO
Center for Advanced Studies
P. 0. Drawer QQ
Santa Barbara, California 93102
10. PROGRAM ELEMENT NO.
1HA326
11. CONTRACT/GRANT NO.
EPA68-01-0759, Task 3
'2. SPONSORING AGENCY NAME AND ADDRESS
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC 20460
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
"5. SUPPLEMENTARY NOTES
Previously printed for limited distribution as EPA 600/4-74-003 (GE74TMP-22), June 1974
. ABSTRACT
Analyzes and documents the rationale and related methodology for monitoring ground-
water pollution caused by mining and mineral processing. Notes that some mines and
waste-disposal areas will continue to be pollution sources long after the mines
have closed, and that because of the broad range of mining activities and diver-
sity of geologic and hydrologic settings, monitoring programs for mineral opera-
tions must be individually considered. Reviews technology for at-source control
of water pollution from mining and points out that some methods used to improve
surface water quality may cause deterioration in groundwater quality. Discusses
existing State and Federal laws and regulations for control of mine drainage
pollution and the inability of most to influence the design, permitting, or
abandonment of underground mines on the basis of water pollution considerations.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Groundwater Movement, *Legal Aspects,
Mine Acids, *Mine Wastes, *Mine Water,
Solid Wastes, *Water Pollution Control,
Water Pollution Sources
*Groundwater Monitoring,
*Groundwater Pol 1uti on,
*Mining Pollution,
*Monitoring Groundwater
02F, 05B, 05D,
05E
1 DISTRIBUTION STATEMENT
Available to the public
sale through the Superintendent of Doc-
Ult>ents, GPO, and the NTIS.
fe
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
84
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
Form 2220-1 (9-73)
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INSTRUCTIONS
1. REPORT NUMBER
Insert the EPA report number as it appears on the cover of the publication.
2. LEAVE BLANK
3. RECIPIENTS ACCESSION NUMBER
Reserved for use by each report recipient.
4. TITLE AND SUBTITLE
Title should indicate clearly and briefly the subject coverage of the report, and be displayed prominently. Set subtitle, if used, in smaller
type or otherwise subordinate it to main title. When a report is prepared in more than one volume, repeat the primary title, add volume
number and include subtitle for the specific title.
5. REPORT DATE
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approvcl, date of preparation, etc.).
6. PERFORMING ORGANIZATION CODE
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7. AUTHOR(S)
Give name(s) in conventional order (John R. Doe, J. Robert Doe, etc.). List author's affiliation if it differs from the performing organi-
zation.
8. PERFORMING ORGANIZATION REPORT NUMBER
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9. PERFORMING ORGANIZATION NAME AND ADDRESS
Give name, street, city, state, and ZIP code. List no more than two levels of an organizational hirearchy.
10. PROGRAM ELEMENT NUMBER
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11. CONTRACT/GRANT NUMBER
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12. SPONSORING AGENCY NAME AND ADDRESS
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14. SPONSORING AGENCY CODE
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15. SUPPLEMENTARY NOTES
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To be published in, Supersedes, Supplements, etc.
16. ABSTRACT
Include a brief (200 words or less) factual summary of the most significant information contained in the report. If the report contains a
significant bibliography or literature survey, mention it here.
17. KEY WORDS AND DOCUMENT ANALYSIS
(a) DESCRIPTORS - Select from the Thesaurus of Engineering and Scientific Terms the proper authorized terms that identify the major
concept of the research and are sufficiently specific and precise to be used as index entries for cataloging.
(b) IDENTIFIERS AND OPEN-ENDED TERMS - Use identifiers for project names, code names, equipment designators, etc. Use open-
ended terms written in descriptor form for those subjects for which no descriptor exists.
(c) COSATI FIELD GROUP - Field and group assignments are to be taken from the 1965 COSATI Subject Category List. Since the ma-
jority of documents are multidisciplinary in nature, the Primary Field/Group assignment(s) will be specific discipline, area of human
endeavor, or type of physical object. The application(s) will be cross-referenced with secondary Field/Group assignments that will folio*
the primary posting(s).
18. DISTRIBUTION STATEMENT
Denote reusability to the public or limitation for reasons other than security for example "Release Unlimited." Cite any availability to
the public, with address and price.
19. & 20. SECURITY CLASSIFICATION
DO NOT submit classified reports to the National Technical Information service.
21. NUMBER OF PAGES
Insert the total number of pages, including this one and unnumbered pages, but exclude distribution list, if any.
22. PRICE
Insert the price set by the National Technical Information Service or the Government Printing Office, if known.
EPA Form 2220-1 (9-73) (Reverse)
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