HEAP LEACH TECHNOLOGY
AND POTENTIAL EFFECTS
IN THE BLACK HILLS
EPA CONTRACT NO. 68-03-6289
WORK ASSIGNMENT NO. 1
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PREPARED FOR
U.S. ENVIRONMENTAL
PROTECTION AGENCY
WATER MANAGEMENT DIVISION
STATE PROGRAMS BRANCH
999 18th STREET, SUITE 1300
DENVER, COLORADO 80202
SEPTEMBER 30, 19S6
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PREPARED BY
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1100 ST< u'i SVRCET, SUITE noo
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1H36 PENNSYLVANIA fcTREET
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EPA 908/3-86-002
HEAP LEACH TECHNOLOGY AND POTENTIAL EFFECTS
IN THE BLACK HILLS
EPA Contract No. 68-03-6289
Work Assignment No. 1
Prepared For
U.S. Environmental Protection Agency
Water Management Division
State Programs Branch
999 18th Street, Suite 1300
Denver, Colorado 80202
September 30, 1986
Prepared By
Engineering-Science
Design-Research-Planning
1100 Stout Street, Suite 1100
Denver, Colorado 80204
V'ith Assistance From
LPA Region Vii
e'.., Siler, George Associates _.
J638 Permsylvania Street UenVfif, Go
Denver, Colorado 80203
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DISCLAIMER
This report has been reviewed by the U.S. Environmental Protection
Agency, Region VIII, Water Management Division, Denver, Colorado, a«d
is approved for publication. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
ii
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ABSTRACT
Typical cyanide heap leach operations for precious metals recovery
are described. A hypothetical facility was placed at three sites in
the Black Hills of South Dakota to facilitate a discussion of environ-
mental and socioeconomic impacts. Since a cyanide heap leach facility
is a closed system, and would not, under ordinary operating conditions,
discharge fluids to surface or ground water, impacts from a properly
designed and operated project would not be a greater threat to environ-
mental quality than industrial developments not using cyanide. Soils,
vegetation, and wildlife habitat would be disturbed throughout the life
of the project. Most of the adverse impacts to these resources would
not continue beyond reclamation. Many safeguards against accidental
release of cyanide-containing solutions are incorporated into mine
designs. However, in the unlikely event of a spill or leak of
cyanide-containing solution, toxic substances could be released to
surface and ground waters. Most impacts would be short-term because of
dilution and cyanide attenuation. Mine development would have
beneficial effects on the economic base but could adversely effect
recreation and seasonal housing. Many impacts could be mitigated by
implementing best management practices and establishing a cooperative
environment between mining officials, local officials, and affected
residents.
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PROJECT SUMMARY
The cyanide heap leaching process is an effective low-cost method
of recovering precious metals from suitable ores that are uneconomic to
process by other methods. Although most operations of cyanide heap
leach facilities have no discharges, certain aspects such as sediment
control may require discharge to surface water. As a result, the U.S.
Environmental Protection Agency (EPA) expects to receive a number of
discharge permit applications for gold mine heap leach facilities.
This study, prepared in response to that need, characterizes the
potential environmental and socioeconomic effects of open pit gold
mining and cyanide heap leach processing in the Black Hills of South
Dakota.
Typical Heap Leach Operation
Cyanide heap leach facilities consist of an open pit mine, waste
rock dump, low grade stockpile (optional), leach pad, process ponds,
and process plant. The life of a typical heap leach facility ranges
from 5 to 20 years with typical production rates from 3,600 to 11,000
metric tons (4,000 to 12,000 short tons) per day. Mining to obtain the
ore for the leaching facilities is similar to most other open pit
operations and includes drilling and blasting followed by excavation
and haulage. Material that is mined is separated into ore, low grade,
or waste rock and is hauled to the leaching facility, low grade
stockpile, or waste rock pile, respectively. Ore may be crushed,
agglomerated with cement or lime, or used untreated as run-of-mine ore.
The leach pad is constructed of materials such as clay, plastic
sheeting, and/or asphalt-type materials which provide an impervious
barrier to the process solution. Leak detection systems are construct-
ed below the heap pad at some operations. The heap is formed by
placing the ore on the leach pad and preparing it for leaching by
methods such as grading or ripping. Process solution containing
cyanide at concentrations ranging from 100 to 1000 mg/1 is then sprayed
on the heap from sprinklers. Some operations re-use heap pads so that
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ore is leached, rinsed, drained, and replaced with unleached ore.
Other facilities use permanent pads where the ore is leached until
extraction becomes uneconomical. As the cyanide solution drains
through the ore it dissolves gold and silver from the ore. The process
solution which contains the metal values, called the pregnant solution,
is stored in the pregnant pond. Two types of process units, carbon
column or zinc precipitation, can be used to remove gold and silver
from the pregnant solution. After the values are removed, the barren
solution is returned to the barren pond and pumped back to the heap for
more leaching. Emergency overflow ponds may be installed to prevent
spills resulting from severe storms. Ponds are lined with impervious
materials, including clay and/or synthetic liners. Monitoring pro-
grams, including visual inspection and monitoring wells, can be used to
provide an indication of leakage.
Rinsing with either fresh water or an alkaline chlorine solution
is generally used to destroy residual cyanide prior to closing spent
heaps. Barren solution and the rinsing solution from neutralization of
the spent heaps are subject to cyanide destruction upon facility
closure. The degree to which specific sites must be reclaimed varies
by state.
Impact Evaluation
Three sites in the Spearfish Creek, Whitewood Creek, and Bear
Butte Creek watersheds In the northern Black Hills of South Dakota were
chosen to assess potential impacts. A hypothetical cyanide heap leach
operation was designed, based on information available from the litera-
ture and mine visits, and imposed on an area of potentially mineable
ore in each watershed so that environmental and socioeconomic impacts
could be assessed. Environmental and socioeconomic resources for each
watershed are summarized below.
Geology. Gold was discovered in the Black Hills of South Dakota
more than a century ago and has been actively mined since then.
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With the increase in gold prices, there is potential for econom-
ically extracting gold from low grade Tertiary replacement de-
posits using heap leaching technology.
Ground Water. Ground water resources, including springs and both
shallow (alluvial) and deeper ground water aquifers, may be
suitable for domestic and agricultural uses. Principal aquifers
in the area are carbonate aquifers (Spearfish Creek and Bear Butte
Greek watersheds) and sandstone aquifers (Whitewood Creek and Bear
Butte Creek watersheds). Water quality of some wells exceeded EPA
secondary drinking water criteria for manganese, iron, or sulfate
and the EPA Maximum Contaminant Level for chromium.
Surface Water. Surface water quality of the Spearfish and Bear
Butte Creek drainages is relatively good, but the water quality of
Whitewood Creek has exceeded EPA standards for some heavy metals
and cyanide because of past mining activities. The water quality
of Whitewood Creek, however, has recently improved. All three
streams support a fishery. Water from Whitewood Creek is used for
irrigation and mining. Spearfish Creek is used as a municipal
water supply for the town of Spearfish. Surface water uses of
Bear Butte Creek are made primarily downstream from the Black
Hills.
Soils. Soils are predominantly loamy and moderately deep. They
support land uses such as forest, wildlife habitat, rangeland, and
recreation.
Vegetation. Although ponderosa pine forest covers most of the
northern Black Hills, grasslands and riparian vegetation exist in
lower slope and valley bottoms. No candidate or Federally-listed
threatened or endangered plant species are known to occur in the
three watersheds.
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Wildlife. Wildlife resources include elk, deer, small mammals,
raptors, and game birds and songbirds. Critical winter habitat
for elk and deer occurs in all three watersheds. The poten
exists for Federally-listed threatened or endangered species to
use the study areas, but without further studies it is not pos-
sible to quantify species occurrence.
Aquatic Life. An important recreational fishery exists in the
northern Black Hills. With the recent improvement in water
quality in Whitewood Creek, there has been an active effort to
increase the productivity of the fishery.
Socioeconomics. The area relies heavily on mining and agricul-
tural activities for its economic base. Diversification into
recreation and tourism has recently occurred. Employment growth
has slowed since the 1970 to 1980 period. Gold mining is the key
influence in determining the current level and pattern of develop-
ment in the area.
A hypothetical cyanide heap leach facility consisting of a mine
pit, waste rock dump, crushing area, leach pad, process plant, pregnant
pond, barren pond, neutralization pond, and overflow pond was described
to facilitate the impact discussion. The operation would cover approx-
imately 1,000 acres and would employ about 100 people throughout a 10-
year mine life. Closure would consist of the neutralization of the
spent ore heap, disposal of the process solution, and decommissioning
and reclamation of all facilities. Reclamation involves disposal of
waste material, dismantling of buildings and roads, decommissioning of
heaps and ponds, grading, topsoiling, and revegetating so that the land
is returned to beneifical use.
Effects of the construction and regular operations of the mine
facility depend on the location of the facility, the areal extent of
the disturbance, and the configuration of the mine facilities. Adverse
effects on ground water supply may occur in conjunction with pumping
drawdown from wells used for mine water. Negative impacts to surface
water and to aquatic life may result from increased sedimentation,
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which would occur primarily during the construction phase. The impacts
from sedimentation may be insignificant if adequate sediment control
structures are used. Impacts to soils and vegetation would be primari-
ly a function of the area disturbed and the amount of post-mining
reclamation. Wildlife would be affected by habitat losses and degrada-
tion and increases in wildlife-human confrontation. The significance
of the effects depends on the species present, the amount of the
habitat lost or degraded and its availability outside the impacted
area, and the intensity of human encounters with wildlife.
Although socioeconomics effects are influenced by the distance
of the operation from developed recreational areas and population
centers, most impacts would be similar regardless of the location of
the actual mining operation. Generally, there would be moderate,
beneficial impacts on employment, income, and the economic base during
the life of the project. This would be accompanied by positive but
Insignificant impacts In population and permanent housing In local
towns. The need for additional services is expected to result in a
negative but insignificant impact on local government budgets.
Local governments would bear almost all of the additional costs
associated with required public services whereas public revenues
generated by the mining operation would be shared by the State, county,
and cities. These revenues would generally be spread over a broader
geographic area than would the demands for services. The significance
of impacts on recreation and seasonal homes is site specific and would
be influenced by the specific location and characteristics of a mining
operation. Cumulative impacts from additional mines should be con-
sidered.
The cyanide process is a closed system and will not discharge any
fluids to surface or ground waters during normal operating procedures.
For purposes of evaluating impacts, two types of accidental releases, a
pregnant pond overflow and a pregnant pond leak, were analyzed for
potential effects. In the analyses both accidental releases contained
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cyanide at concentrations of approximately 200 rag/1 as well as small
amounts of several metals. An accidental release would be highly
unlikely at a well operated and maintained cyanide leaching facility-
Cyanide is a very reactive and relatively short-lived contaminant.
Several chemical and biological processes transform free cyanide into
less toxic forms when it is released to the environment. Effects from
a spill to surface water on aquatic life would be short-term and range
from signficant on a stream adjacent to the facility to insignificant
in downstream reaches because of dilution and attenuation. Some direct
wildife mortality could occur during a spill if animals were to drink
the spilled solution before dilution or degradation of the toxic
components could occur. Impacts from a spill would be short-term and
insignificant to soil and vegetation. In the case of a pond leak,
impacts to ground water could be potentially significant if the water
table is near the surface. The leak would have minimal effects on
surface water and aquatic life unless the distance between the leak and
the ground water discharge point to surface waters was small. Impacts
from a leak on soils would be short-term and insignificant because
potentially toxic solution constituents would be transformed to harm-
less or inert forms within the soil. Generally, no impacts to wildlife
or vegetation would be expected from a leak.
Impacts from heap leach mining and processing can be mitigated by
using various site-specific actions. By locating facilities such as
ponds, plants, and pads which have potential for leaking on sites away
from important aquifers and major streams, the extent of impacts to
ground and surface waters and to aquatic life from accidental releases
will be reduced. The areal extent of surface disturbance is the major
factor affecting soils and vegetation. Minimizing surface disturbance
and avoiding sensitive or unique areas can decrease potential impacts.
In areas that are disturbed, site-specific reclamation measures can be
developed and implemented. Impacts to wildlife result mainly from
habitat destruction. Habitat disturbance can be minimized by avoiding
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sensitive or unique areas. Mitigation of potential socioeconomic
impacts can be accomplished by establishment of a cooperative working
environment between mining companies, local officials, and affected
residents.
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TABLE OF CONTENTS
Abstract
Project Summary
List of Tables
List of Figures
CHAPTER 1 - INTRODUCTION 1
Background 1
Scope of Work and Approach 2
Acknowledgements 5
CHAPTER 2 - HEAP LEACH GOLD MINING AND PROCESSING 6
Ore Type and Preparation 6
Heap Design, Construction and Operation 13
Impoundment Design and Construction 21
Safeguards 24
Site Access 24
Handling and Disposal of Cyanide Containers 25
Monitoring 28
Closure of Heap Leach Facility 30
CHAPTER 3 - EXISTING ENVIRONMENT OF THE BLACK HILLS 32
General Description 32
Geology 40
Ground Water Hydrology 54
Surface Water Hydrology 59
Soils 76
Vegetation 80
Wildlife 89
Aquatic Life 99
Socioeconomics 122
CHAPTER 4 - POTENTIAL IMPACTS AND CONCERNS 170
Hypothetical Cyanide Heap Leach Facility 170
Accidential Release of Cyanide Solution 177
Issues of Concern 181
Geological Resources 182
Ground Water 183
Surface Water 189
Soils 195
Vegetation 198
Wildlife 201
Aquatic Resources 206
Socioeconomics 210
Summary of Projected Impacts 233
Xlll
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TABLE OF CONTENTS (Continued)
7Afl
CHAPTER 5 - OPTIONS FOR MITIGATION 24°
Mitigation of Potential Geologic Impacts
Mitigation of Potential Ground Water Impacts
Mitigation of Potential Impacts to Surface Water
and Aquatic Biota
7A1
Mitigation of Potential Impacts to Soils and ^HJ
Vegetation
Mitigation of Potential Impacts to Wildlife 244
Mitigation of Potential Socioeconomic Impacts 245
CHAPTER 6 - REFERENCES 248
APPENDIX A - EXAMPLE LEAP LEACH PROJECTS 256
Stibnite Project - Pioneer Metals Near Yellowpine, Idaho 256
Wharf Resources - Black Hills, South Dakota 271
References 282
APPENDIX B - CYANIDE CHEMISTRY 283
Overview 283
Chemical Forms of Cyanide 286
Analytical Methods 290
Environmental Fate of Cyanide 295
Cyanide Chemistry of Heap Leach Operations 313
References 334
APPENDIX C - POTENTIAL EFFECTS OF CYANIDE 341
Toxicity of Cyanide to Aquatic Organisms 342
Effects of Cyanide on Vegetation, Livestock and 351
Wildlife
Human Health Effects of Cyanide 354
References 356
APPENDIX D - CYANIDE SPILLS AND RESULTING ENVIRONMENTAL 359
ATTENUATION FACTORS
Accidents from Heap Leaching Practices in the 359
Western United States and Their Impacts
Selection of a Cyanide Attenuation Factor for 365
Chapter 4
References 368
LIST OF TABLES
Number Page
1 Typical Capacity Factors for Design of Heap 23
Leach Operation Process Impoundments
XXV
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TABLE OF CONTENTS (Continued)
2 Mean Monthly Temperatures and Precipitation 34
for Lead, South Dakota, 1951-1974
3 Major Mines in the Northern Black Hills 38
4 Description of Gold and Silver Potential in the 52
Lead-Deadwood Area of the Northern Black Hills
5 Analysis of Selected Ground Water Wells in Spearfish 57
Creek, Whitewood Creek, and Bear Butte Creek Watersheds
6 Flow Rates of Selected Streams in the Northern 62
Black Hills
7 State of South Dakota Surface Water Quality 64
Standards for Streams in the Black Hills Study Area
8 Summary of Water Quality and Sediment Data for 66
Spearfish Creek
9 Summary of Water Quality and Sediment Data for 70
Whitewood Creek
10 Summary of Water Quality Data for Bear Butte Creek 75
11 Soil Associations Occurring in the Spearfish, White- 77
wood, and Bear Butte Creek Watersheds of the Northern
Black Hills
12 Selected Chemical and Physical Characteristics for the 79
Most Prevalent Soil Series in the Whitewood, Spear-
fish, and Bear Butte Creek Watersheds
13 Percentage of Vegetation Types Occurring in the Black 83
Hills National Forest
14 Special Concern Plant Species in the Bear Butte Creek, 88
Spearfish Creek, and Whitewood Creek Watersheds
15 Summary of General Wildlife Resources Characteristics 90
16 Special Concern Wildlife Species Potentially Occurring 98
in the Study Area
17 Summary of Physical Measurements of Whitewood and 103
Spearfish Creeks
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TABLE OF CONTENTS (Continued)
18 Summary of Substrate Measurements of Whitewood
and Spearfish Creeks
19 Species and Numbers of Fish Caught per 100 Meters in 1°7
Recent Studies of Whitewood Creek, South Dakota
20 Average Percent Occurrence of Aquatic Macroinvertebrate 111
Functional Groups in Whitewood and Spearfish Creeks,
South Dakota
21 Number of Aquatic Macroinvertebrate Taxa Collected 113
from Whitewood and Spearfish Creeks, South Dakota
in March Through December, 1981 and March, 1982
22 Diversity of Aquatic Macroinvertebrate Functional 114
Groups in Whitewood and Spearfish Creeks, South Dakota
23 Comparisons of Mean Metal Concentrations in the 116
Composite Macroinvertebrate Samples from Contami-
nated and Reference Stations
24 Species and Numbers of Fish Caught per 100 Meters in 119
Recent Studies of Spearfish Creek, South Dakota
25 Percentage of the Trout Population in Spearfish Creek 120
Greater and Less Than 20 Centimeters (8 inches)
in Length
26 Species and Numbers of Fish Caught per 100 Meters in 123
Recent Studies of Bear Butte Creek, South Dakota
27 Population Trends in the Black Hills Region Counties 127
28 Employment Trends in Black Hills Region Counties 128
29 Composition of Total and Personal Income for Black 129
Hills Counties and South Dakota, 1984
30 Average Annual Unemployment Rates in Black Hills 132
Region Counties, South Dakota, and the United States
31 Composition of Employment for Black Hills Region 133
Counties, 1984
32 Number of Annual Visits to Selected Regional Tourist 136
Sites
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TABLE OF CONTENTS (Continued)
33 Population Change, Lawrence County and Selected Towns, 139
1960 to 1985
34 Composition of Employment in Lawrence County, 1980 to 141
1984
35 Selected 1980 Housing Data in Lawrence County, Deadwood, 143
and Lead
36 Total Assessed Valuation in Lawrence County, Lead, and 154
Deadwood, 1984 to 1986
37 Revenue Sources for Lawrence County, Lead, and 158
Deadwood, 1986
38 Budget Appropriations for Lawrence County, Lead, and 159
Deadwood, 1986
39 Annual Employment and Income Generated By Heap Leach 212
Gold Operation
40 Summary of Impacts for Cyanide Heap Leaching in the 234
Black Hills
A-l Surface Water Monitoring Parameters 269
A-2 Camp Domestic Well and Plant Utility Well Monitoring 270
Parameters
B-l Comparison of Leaching Methods for Total Cyanide 293
Determination in Solid Samples
B-2 Relative Stabilities of Some Cyanide Compounds and 298
Complexes in Water
B-3 Solubilities of Ferrocyanide and Ferricyanide Salts 301
B-4 Stability Constants of Metal-Cyanide Complex Ions 304
B-5 Cumulative Constants, B , for Various Metals Found 305
in Precious Metal Ores
B-6 Degradation of Metal Cyanide Complexes in Phosphate 307
Buffer at pH 7
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TABLE OF CONTENTS (Continued)
B-7 Results of Tests with Cyanide Solutions Added to 314
Columns Containing Native Soil from the Area of
Annie Creek Mine, SD
B-8 Free Cyanide Concentrations in Eleven Locations 318
in the Darwin Heap
B-9 Solution Sample of Chlorine Pond at Stibnite Mine, 320
Idaho (August 24, 1983)
B-10 Total Cyanide Concentrations for Various Heap Leach 322
Operations in California
B-ll Western State Regulations or Guidelines for Neutrali- 326
zation of Spent Heap Leach Piles
B-12 Advantages and Disadvantages of Alkaline Chlorination 330
C-l Toxicity of Cyanide (HCN) to Aquatic Animals 344
LIST OF FIGURES
Number Page
1 Location Map 3
2 Site Locations for Hypothetical Heap Leach Mines 4
3 Flow Chart Diagram of Heap Leach Processing 7
4 Location Map of Northern Black Hills Mining 37
District Surrounding the Lead-Deadwood Dome
5 General Geology of the Black Hills 42
6 General Stratigraphic Section of Black Hills Area 43
7 Stratigraphic Section Showing Location of Upper and 48
Lower Contact Zone in Deadwood Formation
8 Mineral Resource Potential for the Northern Black 50
Hills-Spearfish Creek and Whitewood Creek
9 Mineral Resources Potential for the Northern Black 51
Hills-Bear Butte Creek
xviii
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TABLE OF CONTENTS (Continued)
10 Selected Ground Water Well Locations 58
11 Surface Water Resources 61
12 Elk and Deer Habitat Features 92
13 Aquatic Life Zones in Whitewood Creek 100
14 Locations of Physical Measurements 102
15 Fish Sampling Sites 106
16 Aquatic Macroinvertebrate Sampling Sites 110
17 Socioeconomic Features 125
18 Black Hills Snowmobile Trail System 138
19 Schematic Diagram of the Hypothetical Model Heap 171
Leach Facility
20 Summary of Potential Degradation and Transformation 179
Processes for Cyanide at a Typical Heap Leach
Mining Operation
21 Tourism Routes and Recreation Sites 228
A-l Pioneer Metals Stibnite Project Block Flow Diagram 260
A-2 Typical Pad and Pond Liner at Stibnite Mine 262
A-3 Chlorination Circuit at Stibnite Mine 268
A-4 Wharf Resources Block Flow Diagram 274
A-5 Typical Pad and Pond Liners at Annie Creek Mine 275
B-l The Effect of pH on Dissociation of Hydrogen Cyanide 288
B-2 The Hydrolysis of a Cyanogenic Glycoside, Amygdalin 309
B-3 Cyanide Reactions in Surface Water 311
B-4 Cyanide Degradation in Treated Waste Ore from 321
Stibnite Mine, Idaho
XIX
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CHAPTER 1
INTRODUCTION
BACKGROUND
The cyanide heap leaching process is an important method for the
recovery of gold and silver from low grade ores. The procedure offers
a low cost, effective means of recovering precious metals from ores
which are difficult or uneconomic to process by other methods. It has
been applied both to freshly mined ore from low grade deposits and to
the reprocessing of tailings left by earlier mining operations.
Gold was discovered in the Black Hills of South Dakota more than a
century ago and has been actively mined since then. Most profitable
ore bodies were exploited long ago and, after the ore played out, most
mining operations became uneconomical and were shut down. However,
with the increase in the price of gold, there has been a resurgence in
mining and exploration. Cyanide heap leaching is the preferred tech-
nology for processing ore from revitalized mines when permitted by
geologic and metallurgical conditions.
Section 402 of the Federal Water Pollution Control Act, as amended
by the Clean Water Act of 1977, requires the administrator of the U.S.
Environmental Protection Agency (EPA) to issue permits for the dis-
charge of pollutants to the waters of the United States. The issue of
permits is conducted under the National Pollutant Discharge Elimination
System (NPDES). Although most operations of a cyanide heap leach
facility are closed systems, i.e., have no discharges, certain aspects
such as sediment control may require discharge to surface water. As a
result, EPA expects to receive a number of discharge permit applica-
tions for gold mine heap leach facilities. In order to better carry
out its obligations under the Clean Water Act, the EPA contracted for
this environmental study of the Black Hills to delineate the possible
impacts of heap leach gold mining operations in the area.
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SCOPE OF WORK AND APPROACH
The purpose of this study was to characterize the potential
environmental and socioeconomic effects of heap leach gold raining in
the Black Hills of South Dakota and to prepare a resource document for
the EPA's use in reviewing and assessing proposed heap leach gold
projects in the area. Three watersheds located in the northern Black
Hills of South Dakota were chosen for study. These were the Spearfish
Creek, Whitewood Creek, and Bear Butte Creek watersheds (Figure 1).
The Spearfish Creek watershed was the site of several historical
mining operations. The Annie Creek Mine, Ltd., owned by Wharf Resour-
ces, is the only currently operating cyanide heap leach facility in the
Black Hills. It is located in the Spearfish Creek watershed and is
shown on Figure 2. Whitewood Creek has been substantially impacted by
past mining activities. The reach downstream from Crook City to the
confluence with the Belle Fourche River was listed as a Superfund site
because of contamination by toxic substances in mine tailings. The
Homestake Mine, which has operated along Whitewood Creek for over 100
years, is still active in this watershed (see Figure 2). The Bear
Butte Creek watershed was also the site of historical mining opera-
tions, and several tailings piles still remain. Currently, however,
there is no active raining.
Each of these watersheds contains additional ore which could be
processed in a cyanide leaching facility. To determine possible
impacts, a site was chosen within each watershed for placement of a
hypothetical heap leach mining operation. Each of the selected sites
was in an area of potentially mineable ore near the headwaters of the
major drainage. The locations of the three sites are shown in Figure
2. In the Spearfish Creek watershed, the hypothetical mine site is
located on Raspberry Gulch. The hypothetical mine site in the White-
wood Creek drainage is located on Yellow Creek. In the Bear Butte
Creek watershed, it is located on Two Bit Creek.
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FIGURE 1
LOCATION MAP
North Dakota
"—L
BLAJC
HILLS
I '
V
2
1
^ " 7
\r \
^. • Aberdeen. '-
SOUTH DAKOTA
a
I
o
Sioux Falls*
Nebraska
BELLE FOURCHE
BeU?
Redwater River
WHITEWOOD CREEK
ATERSHEO
SPEARFISH GREEKS
WATERSHED
BEAR BUTTE CREEK
WATERSHED
• RAPID CITY
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FIGURE 2
SITE LOCATIONS FOR HYPOTHETICAL
HEAP LEACH MINES
RASPBERRY
GULCH SITE
YELLOW CREEK SITE
Km
LEGEND
A EXiSTING MINE
• HYPOTHETICAL MINE
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Baseline characteristics were developed for the vicinities of each
mine site. A typical cyanide heap leach operation was then designed,
based on information available from the literature and from tours of
two operating heap leach mines. The typical heap leach mine was then
"placed" in each watershed and potential impacts from each mine were
determined.
A general discussion of gold mining and the cyanide heap leach
process is presented in Chapter 2. Physical, biological, and socioeco-
nomic data on the existing environment of the three chosen watersheds
in the Black Hills are discussed in Chapter 3. Typical mine design and
potential impacts from the construction and operation of the typical
mine in each drainage, as well as for a hypothetical cyanide spill and
leak, are discussed in Chapter 4. Mitigation options are outlined in
Chapter 5. Appendix A contains a description of the two operating
mines that were toured. Data from these mines and information in the
literature were used to develop the typical mine design for this study.
Information on the chemistry and toxicity of cyanide is discussed in
detail in Appendices B and C, respectively. Appendix D contains data
from actual cyanide releases from heap leach operations. This infor-
mation was used to develop the hypothetical spill case in Chapter 4.
All descriptions and analyses in this report are based on informa-
tion available from the scientific and technical literature, State and
Federal agencies, and the mining companies. Although a site recon-
naissance of the three watersheds was performed, no field data were
collected.
ACKNOWLEDGEMENTS
The authors wish to thank Luther Russell of Wharf Resources, Ltd.
in South Dakota and John Parks of the Pioneer Metals Corporation in
Idaho for conducting Engineering-Science, Inc. personnel on informative
tours of their facilities. The socioeconomic analysis contained in
this report was conducted by Hammer, Slier, George, Associates in
Denver, Colorado.
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CHAPTER 2
HEAP LEACH GOLD MINING AND PROCESSING
Heap leach raining and processing is an alternative to conventional
mining and milling operations for recovery of precious metals from low
grade ores. Open pit mining, the mining method used at most heap
leaching operations, requires a near-surface gold and/or silver ore
body in order to reduce waste-to-ore stripping ratios. Open pit mining
is less costly than conventional underground mining methods. Heap
leach processing involves spraying a cyanide solution on the ore which
has been mined, crushed, and formed into a heap, to dissolve the metal
values, collecting the solution containing the dissolved metals, and
recovering the metals from solution. A schematic diagram of the
leaching process is presented in Figure 3. Open pit mining and cyanide
heap leaching has lower capital and operating costs, and reduced
startup time, compared to milling operations. Ore can be economically
leached at grades approximately an order of magnitude lower than those
commonly milled. A disadvantage of heap leaching is that the metal
recovery may not be as good as by conventional milling. Economic
success of heap leaching depends on the ore location, ore preparation,
solution presentation to the ore, solution collection, and the mini-
mizing of solution loss prior to recovery. The steps involved in
cyanide heap leach processing are discussed below. In addition,
details of two operating heap leach mines are discussed in Appendix A.
For a detailed discussion on cyanide chemistry, refer to Appendix B.
ORE TYPE AND PREPARATION
Ore Type
Important ore mineralogical and other aspects required for heap
leaching are as follows:
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FIGURE 3
FLOW CHAftT DIAGRAM OF
HEAP LEACH PROCCESING
CRUSHER
(OPTIONAL)
CYANIDE
MAKEUP
TANK
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The gold (Au) and silver (Ag) should be of very fine (micron
range) size. Ores should be of the disseminated type.
Coarse gold or silver does not leach at practical rates
because of small surface area.
Low-grade ores can be economically treated by heap leaching
but could not be by milling. Some heap leach operations are
treating ores as low as 1 gram (0.03 troy ounces) of gold per
metric ton (short ton) with cut off grades as low as 0.3
grams per metric ton (0.01 troy ounces per short ton).
Ores which have been weathered or are oxidized are amenable
to leaching because gold has been liberated from the original
sulfides. Ores containing an excess of cyanide consuming
constituents such as iron and sulfide may not be suitable for
leaching.
Ores which contain organic carbon will experience low re-
coveries because of the tendency for the carbon to adsorb
dissolved gold or silver.
Ores in which the precious metals are encapsulated in an
inactive mineral, such as quartz, are not amenable to heap
leaching because contact is not possible between the leach
liquor and the metal or metal-containing compound.
The presence of other cyanide-interacting metals such as
copper, cobalt, and zinc will reduce precious metals recov-
ery. These metals can also complex with cyanide and will
reduce the cyanide available for complexing with gold and
silver.
For unknown reasons, manganese in silver ores causes low
recovery. Many deposits of this type remain untreated
because of the problem.
-------
Clay minerals in ores can result in channeling of solution
flow through the heap, which reduces solution contact with
the metals and can result in low recovery. However, such
ores can usually be leached by employing an agglomeration
technique.
Ore Preparation
Mining
Cyanide heap leaching operations generally use ore obtained from
open pit -lining operations. Mining to obtain the ore for the leaching
facilities is similar to most other open pit operations. It indues a
drilling and blasting phase followed by excavation and haulage. The
mined materials are classified either as ore, low grade, or waste rock.
These are broadly defined as follows.
Ore is material containing concentrations of metals that,
after leaching, will provide a profit to the operator.
Materials that contain concentrations of metals that cannot
be recovered at a profit are not classified as ore.
Low grade is material that contains metals at concentrations
that are not economically recoverable, but which must be
mined to provide access to the ore. This material may be
placed in a separate location where it could be leached if
economic conditions change. (Not all mining operations
include a low-grade stockpile.")
Waste rock is material with little or no mineralization but
which must be mined or stripped to provide access to the ore.
The objective of the mining operation is to economically select the
ore, low grade, and waste materials and to transport them to their
respective locations.
The initial activity in the mining operation is the drilling of
blast holes (in sonse cases, only ripping using a dozer is needed).
Besides providing a hole for the explosives, the drill or blast hole
provides a method to sample the ore and to classify the material as
-------
ore, low grade, or waste rock. A sample of the material (cuttings)
from the drill hole is assayed to determine the classification of the
material. The sample is usually assayed for gold and silver, and
sometimes for base metals. Often a leachability test is made. Based
on the assay or leach test performed in an onsite lab, the material
surrounding the drill hole is classified as ore, low grade, or waste
rock.
After the material is blasted, the drill hole locations are
resurveyed and flagged with a color-code designating the material as
ore, low-grade, or waste rock. This flagging guides the excavator/
operator in determining the destination of the material. Materials are
transported to the:
Leach pile or crushing plant, if the material is ore grade.
Low grade stockpile, if the material is to be stored for
possible future leaching.
Waste rock dumps, if the material contains little or no
mineralization.
In practice, the assayed drill holes are usually grouped into ore
zones, low grade zones, and waste rock zones as it is impractical to
selectively excavate the area represented by a single blast hole.
Thus, there is some intermingling of ore, low grade, and waste rock.
The uniformity of the ore zones, low-grade zones, and waste-rock
zones is an important factor in selecting the bench height to be mined.
A thick, uniform ore body will allow a higher bench height, larger
equipment, and a higher production rate than will a thin irregular
deposit. Closely spaced holes and small equipment are required to
selectively mine a thin, irregular deposit, resulting in higher operat-
ing costs and lower production rates. Other factors in selecting the
mining bench height include the thickness and attitude (dip) of the ore
zone, the total tons of ore (reserves) to be mined, and the daily
production rate. The mining bench height normally varies from about 5
10
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meters (15 feet) to more than 12 meters (40 feet). Generally, a thin
Irregular deposit will require a lower bench height while a thicker,
regular, and large deposit will use a higher bench height.
Mining operations can be divided into four separate activities:
drilling, blasting, excavation, and haulage. The following paragraphs
describe these activities at the Pegasus Mine in Zortman, Montana,
which is a large typical heap leaching operation for which information
is available in the literature (Kunze and Short, 1986). The total area
for the mine, leach pads, ponds, and recovery plant at this operation
is approximately 130 hectares (320 acres).
Drilling is accomplished by six drills using down-the-hole hammers
which drill to 7 meters (23 feet) for the 6-meter (20-foot) bench
height. The drill hole spacing ranges from about 3.3 meters by 3.3
meters (11 feet by 11 feet) to 5 meters by 5 meters (15 feet by 15
feet).
Blasting uses a combination of 25 percent emulsion and 75 percent
ANFO (ammonium nitrate/fuel oil mixture). This combination contains
about 40 percent more energy than ANFO alone. The higher energy
increases the fragmentation and provides finer material for the leach
pads. This is one advantage of blasting over ripping, i.e., with
blasting there is more control over breakage size. A method of delayed
blasting is used to minimize the mixing of the ore and waste zones
within the blast. The powder factor used is 0.75 kilograms of explo-
sives per cubic meter (1.25 pounds per cubic yard) of material.
Front end loaders with capacities of 5 to 8 cubic meters (7 to 10
cubic yards) load the 41-metric ton (45-short ton) haulage trucks. The
waste, which is produced at approximately the same rate as ore, is used
to construct the base for the next year's permanent leach piles. Ore
is placed in these piles without crushing. The grade is 0.79 grams of
gold per metric ton (0.023 troy ounces per short ton) of ore. The
cutoff for ore is 0.3 grams of gold per metric ton (0.01 troy ounces
per ton) of ore.
11
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The production rate in 1984 was established as A.8 million metric
tons (5.3 million short tons) of ore and 2.2 million metric tons (2.4
million short tons) of waste rock. The production peaked at 80,000
metric tons (90,000 short tons) per day during this period.
Information is also available in the literature for the Smoky
Valley heap leach operation at Round Mountain, Nevada (Argall, 1985).
At this mine, material with a gold content of greater than 0.51 grams
of gold per metric ton (0.015 troy ounces per short ton) is classified
as ore. The ore is crushed to approximately 1 centimeter (0.5 inch) in
diameter and placed on the leach pile. During the first 9 months of
1985, ore was delivered to the leach pad at the rate of 13,101 metric
tons (14,442 short tons) per day. Material ranging between 0.3 and 0.5
grams of gold per metric ton (0.008 and 0.015 troy ounces per short
ton) is stockpiled in low grade strockpiles. Waste rock has less than
0.3 grams of gold per metric ton (0.008 troy ounces per short ton) and
is sent to waste rock dumps. The mine produces waste to ore at a ratio
of approximately 1.4 to 1.
Drilling is accomplished by four rotary drills which drill IO-
meter (40-foot) deep holes ranging in diameter from 20 to 23 centi-
meters (7.9 to 9 inches). This depth is 2 meters (5 feet) deeper than
11-meter (35-foot) bench height. Blasting of the 5.5- by 5.5- meter
(18- by 18-foot) drill hole pattern is either with ANFO or a slurry
emulsion.
Excavation equipment includes 9.2-cubic meter (12-cubic yard)
front end loaders, an 8.4-cubic meter (11-cubic yard) hydraulic shovel,
and a 5-cubic meter (7-cubic yard) electric shovel. This equipment
loads a fleet of trucks ranging from 40 to 77 metric tons (50 to 85
short tons) in capacity.
Crushing and Agglomeration
The ore is generally crushed to expose the gold and silver values.
Typical ore size for heap leaching ranges from 0.64 to 0.95 centimeter
(0.25 to 0.38 inch) in diameter. These sizes result from the material
being crushed in two or three stages. However, if the ore is of very
12
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low grade, such as at the Pegasus Mine, crushing may not be justified
economically. Run-of-mine, uncrushed ore will require a long leach
time. Crushed ore is generally of higher grade and will leach faster
with better overall recovery. Crushing also produces fines, which must
be handled so as not to cause a decrease in solution permeability
within the pile.
At some operations, there is an excess of fines which must be
agglomerated. In this procedure, an agglomerating agent such as
cement or lime is added to wet ore at the rate of 2 to 4 kilograms (5
to 10 pounds) of cement per ton of ore. Water or sodium cyanide
solution (which initiates the leaching action) is added to provide 8 to
16 percent moisture. The mixture is then tumbled, causing the fine ore
to adhere to the coarser material in an agglomerate. The agglomerates
are allowed to cure during heap building. Only minimal degradation of
the agglomerated ore occurs during leaching in the heap, thus maintain-
ing an open heap and resulting in acceptable recoveries in short
periods of time.
HEAP DESIGN, CONSTRUCTION, AND OPERATION
The heap leaching facility receiving the ore from the mine gen-
erally consists of the following:
An impervious pad upon which the ore to be leached is piled
or heaped. The pad is sloped to a sump or to a pipe system
for collection of leach solution which has percolated down
through the pile. During percolation, gold and/or silver are
dissolved from the ore.
A piping/sprinkler system on top of the heap to distribute
leach liquor to the heap surface.
A pregnant pond to hold gold-containing leach liquor. The
solution is directed to the pond by ditches with impervious
liners, or by pipes.
A pumping system to dispatch the solution to a recovery
plant.
13
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A process plant. Two types of process plants, carbon column
or zinc preciptation, may be used. For either type of plant,
a furnace Is used to produce dore (gold and silver ingots).
The facilities are described in greater detail in the follow-
ing paragraphs.
A barren solution pond which stores solution from the
recovery plant.
Overflow and/or contingency ponds.
Facilities for adding sodium cyanide for leaching, and for
storing lime or caustic for pH adjustment (to the range of 10
to 11).
A pumping/piping system to return recycled leach liquor to
the heap.
Design of Leach Pad and Collection System
Pad Structure
To ensure that solutions used to extract the gold and silver from
the ore are retained, the pad base and the pad structure are carefully
prepared to collect and drain the solution. The soil base upon which
the pad is to be placed must be graded and sloped to permit contain-
ment, and to direct leach solutions to their intended destinations.
The base is compacted to provide structural integrity when the pad is
loaded with ore.
On top of the base, materials are placed to provide an impervious
barrier to the solutions. Two or more layers are usually used. In
some instances, a piping system is placed below the barriers to detect
a barrier failure. The materials employed to build the impervious
barrier are somewhat site specific, and can include natural local clays
with very low transmissivities, bentonites, plastic sheeting, and
asphalt-type materials. The barrier material must be able to withstand
the weight and mechanical movement associated with placing the ore on
the pad without being punctured or cracked. At some operations,
geotextile fabric is placed over barrier materials such as PVC or
14
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Hypalon to provide protection from puncturing. Several inches of
permeable materials (such as crushed ore) are placed on top of the
uppermost layer of the barrier to provide protection and permit ready
passage of solutions to the barrier for collection and direction to the
storage pond.
The Pegasus Mine in Montana uses 30 centimeters (12 inches) of
compacted bentonite shale, a 30 rail PVC layer, and 46 centimeters (18
inches) of mill tailings from an old operation as the base for their
pads (Roper, 1983). At Smoky Valley, in Nevada, leach pads are con-
structed on ground prepared with 5 centimeters (2 inches) of hydraulic
asphalt, 100 to 200 mils of asphaltic rubber covered with rubber chip
spray, and 10 centimeters (5 inches) of asphalt. The pad is approxi-
mately 980 meters (3,200 feet) long and 85 meters (280 feet) wide. It
is inclined to one side and one end where a sump is located to receive
the leach liquor by gravity.
The Smoky Valley pads are reused i.e., ore is placed on the pad,
leached for a predetermined number of days, rinsed, and drained. The
leached ore is then off-loaded and fresh ore is brought in for the next
cycle. The construction of reusable pads is usually quite substantial
so that they can withstand equipment and new ore placement with minimal
damage to the barrier.
At the Pegasus Mine, the heaps are permanent. Ore is permanently
located on the pad area and leached until extraction per cycle becomes
uneconomic. In some operations of this type, fresh ore is added to the
heap as another "lift" and the leaching process is started anew. At a
leaching operations, a PVC or equivalent membrane is placed on top of
the spent ore and serves as the collection barrier for leach of the new
layer.
Heap Building
A variety of equipment can be used to place the ore to be leached
on the pad to form the heap. Commonly used equipment includes bull-
dozers, front-end loaders, conveyor-stackers, and movable radial
stackers. The Ortiz Mine in New Mexico uses a traveling gantry con-
15
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veyor system to place crushed ore evenly on the pad. The size of the
ore being leached influences the method of placement. Uncrushed,
run-of-mine ore requires a haulage truck and dozer, while crushed ore
can be handled with conveyor-stacker type units.
The height of ore heap varies from 2 to 30 meters (8 to 100 feet),
but is generally between 6 to 12 meters (20 and 40 feet). The height
depends on the size of the operation, available pad area, whether the
pad is reusable or permanent, the tendency of the ore to degrade on
leaching, and whether the heap is being handled in a series of "lifts".
Special techniques of dumping and spreading the ore are used to reduce
segregation of fine ore sizes during heap construction at some mining
operations.
When heaps are formed using heavy equipment such as trucks and
dozers, the ore can become compacted. If this occurs, ripping of the
pile is conducted prior to installing the sprinkler irrigation system
to increase infiltration.
At the Pegasus Mine, ore is not crushed, but is spread on the
prepared pad by dozer in 6- to 9-meter (20- to 30-foot) lifts. Each
lift is ripped using a dozer down to a depth of 2 meters (5 feet) from
the surface prior to leaching. After leaching is completed on a lift,
successive lifts of the same height are placed on the same pad up to a
total height of about 30 meters (100 feet). At the Smoky Valley
operation, which uses crushed ore and reusable pads, the ore is spread
to a height of about 4 meters (13 feet) by front-end loader. When
leaching of the heap is completed (gold content in solution drops below
a predetermined level), the residue is removed by front-end loader and
transported to a dump adjacent to the leaching area. The pad is then
made ready for the next cycle of fresh ore.
Leaching
Once the heaps are formed and prepared for leaching e.g. by
ripping, the piping or irrigation system is put in place. The leach
solution can either be sprayed or ponded on the surface.
16
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Leach solution is usually pumped through PVC pipe or equivalent
from the barren storage pond to the heap. If spraying is to be used,
sprinklers are placed in a grid pattern to provide overlapping coverage
of the surface. The droplets from sprinklers must be small enough to
give adequate coverage and distribution of the solution, but not so
small as to readily evaporate or be overly influenced by wind. Ponding
may be applicable in situations where fine ore is involved. However,
unintentional ponding from a spraying system may indicate that a
decrease of permeability in the heap has occurred. Since the leaching
rate is dependent on the amount of oxygen, ponding can also produce
problems with leaching efficiency.
Leach solution application rates for sprinkler systems generally
range from 6 to 18 liters per square meter (0.15 to 0.45 gallons per
square foot) per hour. The proper spraying rate should result in flow
by gravity through the heap without producing ponding. For ponding
systems, leach solution is applied at a rate about 40 liters per square
meter (1 gallon per square foot) per hour. The solution has a pH of 10
or 11. Sodium cyanide content ranges from 0.2 kilograms per metric ton
(0.5 pounds per short ton) of solution to as much as 2 kilograms per
metric ton (4 pounds per short ton) of solution. The amount of sodium
cyanide used depends on the concentration of other cyanide-consuming
constituents in the ore, such as iron, copper, zinc, and sulfide.
These metals and sulfide also react with cyanide making it unavailable
for reaction with gold and silver.
It is important both environmentally and economically that the
leach solution does not escape. The solutions percolating through the
heap must be contained on the pad and drained to a collection sump.
Pad grade, slope, curbs, and lined ditches are carefully maintained to
ensure that loss to the environment does not occur.
At the Pegasus facility, two heap leach pads 5.6 kilometers (3.5
miles) apart are used to treat different ores. At each pile, more than
7,300 meters (24,000 feet) of 5-centimeter (2-inch) pipe deliver leach
solution to 600 to 800 sprinklers. The combined sprinkler capacity for
the two sites is about 300 liters per second (5,000 gallons per
17
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minute). At one property, the barren leach solution contains 1.0
kilogram per short ton (2.1 pounds per short ton) of solution. The
resulting pregnant liquor contains 0.37 kiogram of sodium cyanide per
metric ton (0.74 pound per short ton) of solution. The leach solution
at the other site has respective barren and pregnant sodium cyanide
concentrations of 0.80 to 0.3 kilogram of cyanide per metric ton (1.6
and 0.53 pounds per short ton) of solution. The barren solution pH at
both sites is 11. For the year 1982, it was estimated that sodium
cyanide was consumed at a rate of 0.4 kilogram per metric ton (0.7
pound per short ton) of fresh ore and that 5 to 10 percent of the solu-
tion was lost to evaporation.
The Smoky Valley leach pad is subdivided into 24 sections with
separate, discrete, solution distribution systems. At any one time, 19
sections are under leach, one is being washed, one is draining, one is
being unloaded, one/is being loaded, and the last is open. For those
sections under leach, solution containing 0.5 kilogram per metric ton
(1 pound per short ton) of solution at a pH of 10 is sprayed on the ore
for about 40 days. Each section has 21 sprinklers, each covering about
116 square meters (1,250 square feet). Following leaching, the ore is
washed with fresh water for 2 days and another 2 days are allowed for
draining. Following the draining period, 2 days are used to unload the
heap, and 2 days are required to reload the pad with fresh ore. About
0.3 kilograms (0.6 pounds) of sodium cyanide and 0.2 kilograms of
sodium hydroxide per metric ton of ore (0.3 pounds per short ton) are
consumed in the leach cycle. The resulting pregnant solution contains
0.78 gram (0.025 troy ounce) of gold and 0.2 kilogram (0.3 pound) of
sodium cyanide per metric ton (short ton) of solution.
Metal Recovery
The next step in the process is to remove the values from the
solution and convert them to metal. Solutions coming from the heap are
stored in the pregnant pond which is sized to hold the process solution
volume plus the runoff and leachate from an unusually high precipi-
18
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tat,ion event such as a 100-year storm. The sizing of the pregnant pond
also depends on water balance (whether the site gains water from
precipitation or excessive washing or loses water due to evaporation in
a dry climate).
The solution is pumped from the pregnant liquor pond to a process
unit. Two types of process plants can be used. A carbon column
process plant consists of a series of columns containing activated
charcoal. As the solution is passed through the charcoal, gold is
adsorbed onto the carbon along with the cyanide which is complexed with
gold. In the Merrill Crowe process, which uses precipitation on zinc,
the solution is clarified, deaerated, and reacted with zinc shavings or
powder to precipitate the gold by displacement with zinc. In either
process, after the gold is removed from solution, the remaining solu-
tion is sent to a barren solution storage pond. This pond is generally
sized to hold approximately one-third of the total system solution
volume plus precipitation due to extreme storm events.
When carbon columns are used, the values must be stripped from the
carbon (which is then reactivated and recycled) and converted to metal.
This is usually done by passing a hot, concentrated cyanide solution
through the carbon to desorb the gold and silver complexes. The
resulting solution can then be treated either by electrolysis or by the
Merrill Crowe process. In the case of electrolysis, also called
electrowinning, stainless steel wool is used as the cathode. The strip
solution is circulated through the cell and the gold and silver are
plated onto the wool. The loaded wool is removed periodically, melted
in a furnace, and cast to dore bars (a mixture of gold, silver, and
impurities). This is generally sent to a refinery for metal separation
and preparation of high grade gold and silver.
Each of the Pegasus leach pads hold approximately 40 million
liters (10 million gallons) of leach solution. The ponds receiving the
solution are designed to contain 15 to 20 million liters (4 to 6
million gallons). To prevent loss of solution by leakage, the ponds
are lined with a fine rock base covered with 30 centimeters (12 inches)
of compacted bentonitic shale which is protected with a layer of 36
19
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mil, 1000 denier, 10 x 10 reinforced Hypalon. Solution from the pond
is pumped through clarifying filters to a deaeration tower. Clarifica-
tion i.e., the removal of solids, helps the purity and grade of the
precipitate, while deaeration removes dissolved oxygen and reduces zinc
consumption. Both processes prepare the solution for Merrill Crowe
precipitation by reaction with metallic zinc. Pegasus indicates
recoveries as high as 90 percent from solution even at solution levels
as low as 0.240 grams of gold per metric ton (0.007 troy ounces per
short ton) of solution. After precipitation of gold and silver, the
solution is sent to the barren storage pond where lime and/or caustic,
and sodium cyanide briquettes are added to prepare the solution for
transfer back to the heaps for more leaching.
The gold and silver precipitated with zinc is melted to dore in a
manner similar to treating the steel wool cathodes from electrowinning.
At the Pegasus operation, the precipitate from the Merrill Crowe
process, averages about 20 percent gold and silver. It is melted along
with appropriate fluxes in propane fired, 56.7-kilogram (125-pound)
capacity furnaces. The dore produced at the end of 1982 assayed about
32.5 percent gold, 62.5 percent silver, and 5 percent slag. The dore
produced is sent to a large refinery for conversion to pure gold and
silver. The slag which is produced and skimmed from the melt before
casting the dore bar contained about 300 grams (9 troy ounces) of gold
and 812 grams (23.7 troy ounces) of silver per metric ton (short ton).
The slag is crushed and screened, sampled for precious metals content,
and sent to an outside refinery for reclaim of its values. In 1982,
approximately 160 metric tons (177 short tons) of slag were sent for
refining and recovery of its contained gold.
At Smoky Valley, solution from the heap sections under leach is
collected in a 9.5-million liter (2.5-raillion gallon) holding pond.
Pregnant solution, which contains approximately 8.6 grams of gold per
metric ton (0.25 troy ounce per short ton), is then pumped to carbon
columns. There are five columns arranged in series. Each column is
3.6 meters (12 feet) in diameter, 2 meters (8 feet) high, and contains
about 3,000 kilograms (7,000 pounds) of 12 X 30 mesh carbon. Solution
20
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is introduced to each column such that there is counter-current flow
through the carbon. To achieve a counter current flow, the carbon is
advanced by water eductors in an upstream direction at the rate of 1.1
metric tons (1.2 short tons) per day. The carbon removed from the
first column each day contains about 8,600 grams per metric ton (250
troy ounces per short ton) of gold and silver. Barren solution from
the number five column is treated with cyanide and caustic and is
returned to the heaps for more leaching.
The gold and silver loaded carbon from the adsorption section is
transferred to a preheat vessel and then to the stripping vessel.
Strip solution contains 0.5 percent sodium hydroxide and 0.25 percent
sodium cyanide and is heated to 140 degrees Centigrade (°C) (280
degrees Fahrenheit (°F)). The strip solution, assaying about 300 to
800 grams of precious metal per metric ton of solution (10 to 15 troy
ounces per short ton), is then processed through the electrowinning
circuit. Steel wool cathodes are used and when loaded they are melted
with appropriate fluxes (borax, nitrate, and silica sand), in crucible
reduction furnances. The iron is slagged off and dore buttons of 65
percent gold and 34 percent silver are produced. These are remelted
and cast into 30,000 to 34,000 gram (1,000 to 1,100 troy ounce) bars,
which are shipped to a refinery for final treatment. Approximately 2.4
million grams (79,000 troy ounces) of gold in dore is produced each
year, which represents about 63 percent of the gold contained in the
ore treated. Silver recovery is about 30 percent. The stripped carbon
is reactivated in an indirectly fired rotary kiln at 650 °C (1200 °F),
washed with nitric acid to remove carbonates and/or heavy metals, and
recycled to the columns.
IMPOUNDMENT DESIGN AND CONSTRUCTION
Basis of Design for Process Impoundments
The design basis for ponds is site specific and depends on terrain
and operating practice. However, all ponds must prevent any loss of
solution either from leakage or overflow. Pond design criteria include
minimum storage capacity, operating capacity, storage for runoff, and
21
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freeboard. The ponds must also have an impervious liner to prevent
leakage through the bottom and sides. Capacity factors that have been
used for pond design are presented in Table 1.
Options for pond design and construction include pond geometry as
to length, width, and depth; nature of the pond liner (clay, synthetic,
single, or double); and aspects of the operation such as inflow,
pumping arrangements, and access requirements.
Materials Used in Construction
Materials used for pond liner construction on a prepared, compact-
ed soil base include clay, synthetic liners, and sized and graded
gravels. Clays are not generally used in direct contact with solution
because gold can be adsorbed onto the clay which would represent a loss
of value. Synthetic PVC or Hypalon liners are generally used as the
upper most layer. Some operations have used double, or even triple
liners. When two or more layers of synthetic material are used, they
may be separated by as much as 30 centimeters (12 inches) of pea gravel
or other material. A collection pipe system is sometimes placed in the
gravel to detect any leakage through the upper layer.
Maintenance Programs
The ponds are usually drained and inspected visually at least once
each year for punctures or for breaks in the glued seams. Pipe under-
drains for leak detection are usually checked on a daily basis. If a
leak is detected, appropriate steps can be taken to correct the prob-
lem. In some cases leak testing is done by monitoring pond levels with
surveying equipment and comparing that data to evaporative loss for the
same period.
Runoff Diversion Provisions
Surface water runoff is diverted around both the pond areas and
the entire process facility. Unlined diversion ditches are sized to
handle a major 100-year climatic event or to meet State requirements.
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TABLE 1
TYPICAL CAPACITY FACTORS FOR DESIGN OF HEAP
LEACH OPERATION PROCESS IMPOUNDMENTS
Operating Volume
Operational Surge
Climatic Surge
Pregnant Solution
Pond
1/3 of final capacity
Contain draindown or
draindown and rinse
volume
Contain 100-year,
24-hour storm runoff
from pad and on pond
or
Contain 100-year,
1-year runoff from
pad and precipitation
on pond
or
Contain snowmelt from
a 100-year snowpack on
pad and pond.
0.3 meters (1 foot) of
freeboard
Safety Factor
Source: Modified after Hutchison, 1985.
Barren Solution
Pond
1/3 of final capacity
None
Contain 100-year,
24-hour storm on pond
or
Contain 100-year,
1-year precipitation
on pond
or
Contain snowraelt from
100-year snowpack
0.3 meters (1 foot) of
freeboard
23
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SAFEGUARDS
The type of safeguards selected at heap leach operations depends
on legal requirements, the proximity to populated areas, degree of
interconnection between surface and ground water systems, and adjacent
land uses. Some backup systems that have been employed are discussed
below.
Auxiliary power capacity may be installed to provide con-
tinuous pumping to maintain proper pond levels in the event
of failure of the regional power system or onsite generating
system.
Emergency ponds may be installed to prevent spills resulting
from severe storms or inadequate freeboard.
Leak detection systems under pads and ponds have been re-
quired by some regulatory programs because of concern over
liner types, adequacy of seaming, and possible damage to the
pad during loading. Some operations have been constructed
with double or even triple liners. Leak detection systems in
use include down-gradient monitoring wells and direct moni-
toring techniques such as pipe underdrains.
Spill containment plans outlining procedures for the treat-
ment and handling of spilled materials and notification of
authorities can help minimize overall impact of a spill.
SITE ACCESS
Human
Areas containing exposed process solutions are generally fenced
with a 2.4-meter (8-foot) tall chain link fence topped with barbed wire
and posted with appropriate warning signs. The entire site may also be
fenced with a standard four-strand, barbed-wire fence.
24
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Wildlife
Wildlife access is controlled by the use of fences. Other mea-
sures that have been used to protect wildlife are netting or flagging
over ponds and covering ditches with rock. A 2.4-raeter (8-foot) tall
woven wire fence topped with barbed wire is commonly used to exclude
large mammals such as elk and deer. Livestock and the larger fur-
bearing mammals (coyote and grey fox) are also kept out with this type
of fence. Similarly designed gates provide human access while pre-
venting these animals from bypassing the fence.
The placement of flagging or netting over open ponds and rock
covers over drainage ditches restricts access to these facilities for
mammals that can climb over, go through, or dig under the fence, and
for birds. A fine mesh netting over ponds, and a mixture of large and
small rock in the ditches, is the most effective combination.
HANDLING AND DISPOSAL OF CYANIDE CONTAINERS
Sodium cyanide (NaCN) is available in two widely used forms: a
briquette form and a granular form. Both forms can be delivered to
the operating facilities in either 208-liter (55-gallon) drums (usually
used at smaller operations) or Flo-Bin containers (usually used at
larger operations). Proper education and training about health haz-
ards, basic safety precautions, and proper handling, storage, and
disposal procedures is of upmost importance not only for the safety of
the workers but also for the success or failure of an operation
(Stanton et al., 1985). Appendix C contains more information about the
human health effects of cyanide.
Safety Precautions
The basic safety precautions for people working with sodium
cyanide include the following:
25
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Wearing approved dust respirators when there is danger of
inhaling cyanide dust. Respirators are approved by the
Mining Enforcement and Safety Administration or by the
National Institute for Occupational Safety and Health
(NIOSH).
Avoiding skin contact with cyanides by wearing protective
gloves when handling solid cyanides and rubber gloves when
handling cyanide solutions, and by washing hands and gloves
thoroughly with running water after handling cyanides.
Wearing approved chemical splash goggles when handling
cyanide solutions and when there is danger of splashing.
Sweeping up spilled cyanide and placing it in suitable,
clearly labeled containers; treating the contaminated area
with dilute hypochlorite solution to destroy the residual
cyanide; then flushing the area with water.
Preventing acids or weak alkalies from contacting sodium
cyanide.
Storing sodium cyanide in dry, well-ventilated areas and
keeping containers closed and their contents dry.
Posting warning signs, no smoking signs, and no eating signs
•
where cyanide is being used.
Handling Cyanide Containers
In order to prevent the formation of hydrogen cyanide gas, drums
of sodium cyanide are stored in dry buildings segregated from acids,
weak alkalies, and strong oxidizing materials such as nitrates. Other
precautions taken include removing from storage only the quantity of
cyanide required for immediate use, opening cyanide drums in the areas
in which the cyanide is to be used, ventilating the area, replacing
container covers immediately, and picking up any spillage. The same
safety precautions apply to the use of Flo-Bin containers, although
they may also be stored outdoors.
26
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Treatment and Disposal of Cyanide Containers
According to U.S. Department of Transportation (DOT) regulations,
steel drums that contained sodium cyanide are not returnable and cannot
be reused for the transportation of other wastes except under special
conditions approved by the EPA. Because some residual cyanide can be
expected to occur in the drums, they are considered by the EPA's
regulations as an acutely hazardous waste and are subject to Federal
regulations for the management of hazardous wastes (40 CFR 261; 49 GFR
173.28).
Procedures used for the handling and disposal of spent cyanide
drums are as follows:
Each empty drum is flushed with a large volume of water and
drained to an operation pond or other facility which would
introduce the solution back into the process system. Each
drum is washed at least three times until no cyanide remains
in the drum.
The labels on the drum are removed or obliterated. The drum
is then crushed or mutilated so that it cannot be reused.
Following these procedures, the drum is considered nonhazardous
and may be disposed of accordingly. Approval of the plan and the
disposal site (such as a local sanitary landfill) is obtained by local
officials prior to implementation of operations. Onsite disposal of
the spent barrels is also possible when local and State regulators
approve.
Handling Spills
Spilled material can be shoveled and/or swept into a drum or
suitable container. In order to inhibit the formation of hydrogen
cyanide gas, the following precautions can be taken:
Covering the spill to reduce the solution of sodium cyanide
and reduce run-off.
Rinsing the area with dilute hypochlorite solution to destroy
the cyanide.
27
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Adding a small amount of caustic (0.6 kilograms per 100
liters or 5 pounds per 100 gallons of water) to keep the pH
of a sodium cyanide solution around 12 and minimize hydrogen
cyanide formation.
MONITORING
For many operating heap leach projects, monitoring programs are
extensions of sampling and data gathering efforts established during
environmental baseline programs. Although monitoring cannot control a
failure, it can provide early warning that a problem exists so that
appropriate mitigation can be identified and undertaken.
The two basic types of leak detection systems are monitoring wells
and visual inspection systems. Most visual inspection systems incor-
porate variations of the French-drain principal. In these systems, a
grid of perforated piping is contained within an aggregate filter under
the liner, or between two liners. This allows leaking solution to
drain to an outlet downgradient of a heap, for visual identification of
leaks. Various types of leak detection systems are described below.
Monitoring Wells
Potentially affected aquifers can be monitored by the sampling of
wells and springs. Monitoring wells should be down-gradient from the
cyanide leaching operation, although upgradient wells may be sampled as
indicators of background conditions. Commonly, sampling is conducted
quarterly. The selection of parameters to be analyzed is governed by
State agencies and depends on site-specific conditions. In order to be
effective, monitoring wells should be as close to the operations as
possible in locations where subsurface waters will be intercepted.
Problems with monitoring wells may arise in historical mining
districts where underground mine workings alter the expected flow
direction and lead to improper placement of the wells. Problems can
also occur in situations where the slow rate of ground water movement
results in a time lag that can lead to significant soil volumes being
contaminated before monitoring detects the pollutant.
28
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Lysimeters
Lysimeters are used for detecting liquids in unsaturated or
partially saturated zones of the soil. Lysimeters generally detect
leaks earlier than do monitoring wells. One type of lysimeter consists
of a porous ceramic cup in which a vacuum is created to draw In from
the unsaturated or partially saturated soil zone. The liquid is then
forced to the surface for collection and analysis. Although lysimeters
cannot locate a leak, in sufficient numbers they can help evaluate the
location of a contaminant plume. Problems with lysimeters have been
documented and include plugging, inadequate sample volumes, and corro-
sion.
Leachate Collection System
A leachate collection system can be used to detect and sample
leaking solution immediately beneath the liner of the leach pad or
process pond, and employs the French-drain principal. The leachate
collection system commonly consists of a grid of perforated piping
within an aggregate filter under or between liners. Solution drains
downgradient through the piping and leakage Is visually detected.
Although such systems can provide a prompt indication of leakage, they
can be expensive and may plug with time.
Grid Leak Detection System
The grid leak detection system, designed by Johnson (1983) con-
sists of a grid network of wire placed under the liner. To our know-
ledge this system has not been used, however this technology may be
applied in the future. In this system, any leakage beneath the liner
would cause electrical property changes which would be detected by a
data logger. Although this system would be capable of detecting the
location of a leak, the leaked material would be unavailable for
sampling.
29
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CLOSURE OF HEAP LEACH FACILITY
Decommissioning
Spent Leach Heap Piles
Rinsing of the heap is generally used to destroy residual cyanide
prior to closing spent heaps. The rinsing procedure usually consists
of applying either fresh water or an alkaline solution containing
chlorine to the heap. The requirements for neutralization of cyanide
in spent heaps vary by State (refer to Appendix B, Table B-ll). The
resulting leachate is treated to destroy cyanide and the effluent is
recycled through the heap. This process is repeated until the cyanide
concentration in the leachate is below the level required by regulatory
agencies. Methods for neutralizing cyanide in water are described in
Appendix B. Where a fresh water rinse is used (Nevada), the operator
is required to rinse with water until the pH of the effluent is 8.5 for
three consecutive days. In the few cases where the pads are reused,
such as Smoky Valley, the spent ore is hauled and disposed in an area
suitable for a permanent repository. The regulations for disposal vary
by State; in Nevada, where Smoky Valley is located, a catch basin
downgradient from the spent ore is required so that leachate may be
sampled.
Process Cyanide Solutions
Barren solution, and the rinsing solution from neutralization of
the spent ore heaps are subject to cyanide destruction upon facility
closure. Cyanide destruction methods are based on oxidation (alkaline
chlorination, hydrogen proxide, Inco process) and biological processes.
The methods typically used at heap leaching operations are alkaline
chlorination and hydrogen peroxide. The alkaline chlorination method
destroys cyanide ion, hydrogen cyanide, and cyanide from most metal
cyanide complexes with the exception of iron cyanide complexes. The
hydrogen peroxide method destroys cyanide ion, hydrogen cyanide, and
cyanide in copper, zinc, and nickel cyanide complexes. If copper is
added, iron cyanide complexes may be precipitated. An added benefit of
hydrogen peroxide is metals are precipitated as hydroxides. The major
30
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treatment processes that may be used at leaching operations are sum-
marized in Appendix B. After the neutralization is completed, the
solution is evaporated or sprayed on an environmentally suitable area.
Reclamation
Reclamation of a heap leach site involves disposal of waste
material, dismantling of buildings and roads, decommissioning of heaps
and ponds, grading, topsoiling, and revegetating so that the land is
returned to benefical use. The degree to which specific sites must be
reclaimed varies by State. In some states, including South Dakota,
reclamation requirements are decided on a case-by-case basis. In
general, reclamation should reduce or minimize erosion, provide stable
slopes, and reproduce natural vegetation levels. Using appropriate
reclamation technology, vegetation can be restored to most sites, as
long as a stable surface is provided, topsoil is available, and appro-
priate seeding methods are used.
The mine pit is generally not backfilled. Therefore, it is
important that slopes be stablilized through methods such as revegeta-
tion of the benches to prevent sloughing and reduction of slopes.
Heaps and waste piles may or may not be revegetated, depending on
previous and future land uses. In either case, however, they can be
stablilized and designed to minimize erosion. This is particularly
important if waste piles are located in drainages. Roads also may
remain, depending on the desire of the landowner. If left in place,
banks can be revegetated to protect against erosion.
31
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CHAPTER 3
EXISTING ENVIRONMENT OF THE BLACK HILLS
GENERAL DESCRIPTION
The Black Hills are an Isolated extension of the Rocky Mountains
located on the west-central border of South Dakota (see Figure 1).
They extend 190 kilometers (120 miles) from north to south and between
60 and 80 kilometers (40 and 50 miles) from east to west. Most of the
Black Hills are located in South Dakota with the western edge extending
a short distance into Wyoming. The Black Hills are the only area of
mountainous terrain in the western Great Plains. The uplifted hills
are surrounded by rolling foothills and broad valleys which gently dip
to the prairies.
Since the area was first settled in the 1830's, forestry and
mining have been the two dominant industries in the Black Hills.
However, over the past few decades, recreation and tourism have become
increasingly important to the economy of the area.
The flora of the Black Hills contains a diverse assemblage of
plant species representative of the Rocky Mountain region, the northern
boreal forest, the eastern Great Plains, and the eastern deciduous
forest. Ponderosa pine is the predominate timber species and covers
nearly 90 percent of the Black Hills. The regional wildlife resources
are diverse, with elk, deer, and pronghorn antelope as the major game
species. Local wildlife composition is strongly influenced by the
variety of topographic conditions and vegetation types present.
The higher portions of the hills rise from 900 to 1,200 meters
(3,000 to 4,000 feet) above the surrounding plains and reach an alti-
tude of more than 2,000 meters (7,000 feet) at Harney Peak. The
hogback ridges of the Cretaceous Fall River sandstone form an outer
encircling rim to the Black Hills. Within the hogbacks, the Red Valley
extends completely around the uplift. The valley ranges in width from
a narrow band to several miles at the widest point. Situated above the
Red Valley are the Foothills and MInnekahta Plains which consist of
32
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broad, rolling plains marking the transition from plains to mountainous
topography. The Limestone Plateau, which is an escarpment that is
widest along the northwestern edge of the Black Hills lies above the
Foothills and Minnekahta Plains. The central area is a granitic and
metamorphic core highly dissected by ridges and mountains scattered
among large parklike valleys with canyons extending out to the north,
east, and south.
The Black Hills uplift is drained by relatively small streams
radiating from the divide formed by the western part of the Limestone
Plateau. Strearaflows are greatest where drainage is toward the north
and east. Many streams disappear or lose much of their flow as they
cross the tilted sedimentary beds near the perimeter of the uplift.
Two major drainage basins lie in the Black Hills. To the south lies
the Cheyenne River basin and to the north is the Belle Fourche basin.
Water yield is greater in the northern Black Hills than in other areas
of the hills.
Climate
Although the climate of the Black Hills is strongly influenced by
air masses from the Gulf of Mexico in the summer and by polar air
masses in the winter, this isolated group of forest-covered mountains
has a climate of its own. Warm chinook winds and frequent sunny skies
make the Black Hills area the warmest part of South Dakota in the
winter. During summer, the higher elevation of the Black Hills results
in the area having cooler temperatures than the rest of the state.
Average monthly temperatures in Lead, South Dakota range from -5° C
(23° F) to 20° C (68° F) (Table 2) (Ruttner, 1980). Temperature
extremes vary from -33° C (-27° F) recorded in December 1968 and 35° C
(95° F) recorded in June 1970 and August 1969 (Ruttner, 1980). The
freeze-free season is quite short high in the Black Hills where brief
freezing has been known to occur at any time of the summer. The
growing season ranges from 50 days at the highest elevations to a
maximum of 140 days at the lowest elevations, with an average of 119
days (Spuhler et al., 1971).
33
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Month
TABLE 2
MEAN MONTHLY TEMPERATURES AND PRECIPITATION
FOR LEAD, SOUTH DAKOTA 1951-1974
Monthly Average
Temperature
Monthly Average
Precip itatlon
Monthly Average
Snow, Sleet
January
February
March
April
May
June
July
August
September
October
November
December
Year
0
-4
-2
-1
4
10
15
19
19
13
8
0
-2
6
C
.67
.89
.06
.22
.3
.7
.8
.5
.4
.39
.89
.67
.78
<°F
(23
(26
(30
(39
(50
(60
(67
(67
(56
(47
(33
(27
(44
)
.6)
.8)
.1)
.6)
.5)
.3)
.7)
.1)
.2)
.1)
.6)
.2)
.2)
mm
30
40
54
96
117
109
63
56
49
36
40
39
735
(inches)
.2
.6
.6
.5
.5
.9
.0
.8
.9
.4
.3
(1
(1
(2
(3
(4
(4
(2
(2
(1
(1
(1
(1
(28
.19)
.60)
.15)
.80)
.62)
.31)
.50)
.24)
.93)
.45)
.61)
.55)
.95)
mm (
389
554
681
770
190
33
0.0
0.0
64
230
455
505
3,876 (
inc
(15
(21
(26
(30
(7
(1
(0
(0
(2
(9
(17
(19
152
hes
.3)
.8)
.8)
.3)
.7)
.3)
.0)
.0)
.5)
.1)
.9)
.9)
.6)
Source: Modified from Ruttner, 1980.
34
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Average precipitation varies from 410 millimeters (16 inches) in
the southern portion of the Black Hills to almost 740 millimeters (29
inches) in the northern portion (Table 2). Rain and snow are often
formed when the prevailing winds are abruptly forced up the mountain-
sides. Most of the yearly precipitation occurs from April through
September, with the heaviest events in April, May, and June in the form
of thunderstorms associated with hail (Fox, 1984). There is much local
variation in rainfall, and although midsummer precipitation is light,
there are generally daily local showers at variable locations in the
Black Hills. A rainfall of 25 millimeters (1 inch) or more may be
expected on the average of about once a year, and storms depositing 50
millimeters (2 inches) or more of rain per hour occur about once in 10
years. Annual snowfall averages almost 4 meters (13 feet) (Table 2),
with a snow cover of 30 millimeters (1 inch) or more on an average of
68 days per year. Net annual evaporation loss is approximately 300
millimeters (12 inches) (Montgomery, 1985).
The area is subject to violent thunderstorms. An unusual and
excessive rainfall occurred in June 1972, causing a great flood in the
Rapid City area. An almost stationary group of thunderstorms formed
over the eastern Black Hills and produced nearly 380 millimeters (15
inches) of rain in a 6-hour period. The resulting floods were the
highest ever recorded in South Dakota and at least 18 of the 27 streams
where peak flows were computed experienced flows that exceeded the
50-year flood (Schwarz et al., 1975). The rainfall amount constituted
about 65 percent of the probable maximum precipitation for a 26-
square-kilometer (10-square-mile) area (Schwarz et al., 1975). This
flood produced the greatest loss of life in the United States from a
single flood event since 1927, with 236 deaths and a total estimated
damage of $150 million.
History
Gold mining activities are not new to the Black Hills area. Some
prospecting and minor production of placer gold may have begun as early
as 1834 in the northern Black Hills, but large-scale placer operations
and the discovery of the first lode claims did not take place until
35
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gold was discovered in French Creek by a party of prospectors accom-
panying an expedition organized by General George duster in 1876. At
the time, prospecting was difficult because the Black Hills were inhab-
ited by the Sioux Indian Nation. However, in February 1877, a treaty
was negotiated with the Indians and mining activities flourished.
Black Hills gold production boomed from 1898 to 1917, with produc-
tion of almost 12 million grams (400,000 troy ounces) of gold in good
years. The decline just prior to World War I occurred because costs
for labor and supplies skyrocketed with the pending war. All mining
ceased except in the Homestake Mine near Lead, South Dakota. The
Homestake Mine was an important gold discovery made by the Manual
brothers in 1876. The Manual's sold their claim to California Senator
George Hearst for $70,000. Hearst acquired and consolidated properties
and Homestake became the most prolific gold producer in North America.
The Homestake Mine has produced in excess of one billion grams (35
million troy ounces) of gold (Coin Lake Gold Mines Annual Report,
1985). Homestake is located in the Lead mining district (Figure 4).
Second to Homestake in gold production in South Dakota was the
Golden Reward mine located 5 kilometers (3 miles) from Lead in the Bald
Mountain mining area. The Bald Mountain mining area includes the
Portland and Ruby Basin mining districts (Figure 4). Mining occurred
from 1888 through 1918 and 40 million grams (1.3 million troy ounces)
of gold were produced. The Golden Reward Mine mined the oxidized "red
ores" which were followed underground until the ore changed to a more
refractive blue ore which could not be successfully treated with the
technology of the times (Coin Lakes Gold Mines Limited Annual Report,
1985).
During the turn of the century, mining activities were occurring
in all of the major mining districts in the northern Black Hills (Table
3). The Garden-Maitland district produced gold and silver from verti-
cal fractures in the basal Deadwood conglomerate and from replacement
deposits in the lower contact zone (see geology discussion later in
36
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FIGURE 4
LOCATION MAP OF NORTHERN BLACK HILLS MINING
DISTRICTS SURROUNDING THE LEAD-DEADWOOD DOME
RUBY'BASINyb LEAD
DISTRICT /§ DISTRICT
(SHAPIRO AND CRIES. 1870)
-------
TABLE 3
MAJOR MINES IN THE NORTHERN BLACK HILLS
Mine and District
Dakota Mining and Milling-
Portland District
Gilt Edge Mine - Galena
District
Golden Reward - Lead
District
Hidden Fortune - Lead
District
Homestake - Lead
District
Horseshoe Mogel - Ruby
Basin District
Imperial - Portland
District
Maitland and predecessors -
Garden-Maitland District
Bald Mountain-Portland-
Trojan - Portland and
Ruby Basin District
Reliance and New Reliance -
Portland District
Spearfish-Victoria-
Ragged Top District
Wasp No. 2 - Lead
District
a/
Unless otherwise noted
Source: Parker, 1981.
Years of Operation
1902-1906
1900-1916, 1937-1941
1887-1913
1904-1905
1878-to date
1394-1919
1902-1906
1903-1906, 1930's
1908, 1912-1923
1930's, 1946-1959
1902-1916
1901-1905, 1912
1897-1917
Gold
Production^
(Dollars)
544,000
749,000
21,000,000
188,000
980,089,720 grams
(31,510,612 oz.)
7,000,000
Not available
2,851,600 grams
(91,681 oz.)
12,000,000
610,000
972,000
2,767,000
38
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this chapter) from 1880 through 1910. In the Ragged Top district, gold
was discovered in 1896 and production ended in 1916. The gold was
produced from Pahasapa Formation deposits.
In the Galena district, gold was discovered in Bear Butte Creek in
1875. The placer deposits were largely disappointing, so prospectors
began looking for lode ore. The ore that was discovered was rich in
silver and lead as well as gold. The ore was in galena (lead ore)
rather than the limestone carbonate ore found in the other districts.
The largest mine in the Galena area was the Gilt Edge Mine along
Strawberry Gulch. It was in operation from 1900 to 1902, 1905 to 1916,
and 1937 to 1941. The operation in the 1940's was the third largest
mining operation in the Black Hills.
Free-milling gold ores were played out by the end of the 1880's,
so various processes were developed to mill the ore to extract more
gold. In the late 1880's J.S. McArthur and R.W. Forrest developed a
cyanide process for removing gold from oxidized and refractory ores.
In the Black Hills, it was originally used to extract gold from tail-
ings of the mercury amalgamation process, but was later used as a
cyanidization process alone. Once the cyanide liquid was charged with
gold, it was run over zinc shavings so the gold would precipitate out.
As the cyanide process was refined, increased amounts of gold could be
exracted from all but the most refractory deposits.
Past mining and milling operations have produced numerous tailings
and waste piles in the Black Hills. Mining-related pollution in
Whitewood Creek was reported as early as the turn of the century
(Parker, 1981), and tailings were discharged directly to nearby streams
for nearly 100 years. Recent regulations controlling mining and
mineral processing together with improved technology, have made mining
far less destructive to the environment than in early days.
Selected Watersheds
Three watersheds located in the northeastern Black Hills were
selected for examination: Spearfish Creek, Whitewood Creek, and Bear
Butte Creek (see Figure 1). These were selected on the basis of
39
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proposed mining activity, impacts of past mining, socioeconoraic pat-
terns, and variation in physical and environmental characteristics.
Spearfish Creek represents a baseline drainage where mining, both
past and present, has not severely impacted the area. Currently, there
is one active mining operation in the area with several other projects
proposed. The Spearfish Creek drainage is relatively undeveloped with
some recreational use and summer homes.
The Whitewood Creek drainage was the site of extensive historical
mining activity. Over time, there were approximately 65 mills in the
Whitewood Creek watershed. These mines and mills severely impacted
water quality in the drainage. A 29-kilometer (18-mile) segment of
Whitewood Creek is currently on the National Priorities List as a
hazardous waste site under the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA) because of concern about the
toxicity of heavy metals in mine tailings previously deposited along
the length of the creek. The only remaining active mine is Homestake,
North America's largest gold mine. The watershed is also a more
populated area, and contains a wastewater treatment plant discharging
to the creek north of the town of Deadwood.
Bear Butte Creek has had intermittent mining activity since 1875
when placer gold deposits were first discovered. Currently, no active
mining is occurring, but operations have been proposed. The Bear Butte
Creek drainage represents an essentially undeveloped area.
The existing environment in the study area is described below.
Specific discussions on the individual watersheds are included where
appropriate.
GEOLOGY
Regional Geology
The Black Hills uplift is a north- to south-oriented doubly-plung-
ing anticline formed during the formation of the Rocky Mountains 60 to
65 million years ago. The uplift consists of an eastern and western
block, with the eastern block structurally higher than the western
AO
-------
block. The blocks are separated by the Fanny Peak monocline (DeWitt et
al., 1986). The central core of the anticline consists of Precarabrian
(more than 600 million years old) metamorphic and Tertiary (63 million
to 1 million years old) igneous rocks and is surrounded by concentric
outcrops of Paleozoic (600 million to 230 million years old) and
Mesozoic (230 million to 63 million years old) sedimentary rocks which
dip away from the core (Figure 5). The Precambrian metamorphic rocks
and the Paleozoic and Mesozoic sedimentary rocks have been intruded by
a series of west-northwest trending stocks, laccoliths, and dikes of
Tertiary age. Erosion of the uplifted sedimentary strata has exposed
the older core rocks and created the present topography of the Black
Hills.
Geology of the Study Area
The Spearfish Creek, Whitewood Creek, and Bear Butte Creek water-
sheds are located on the northern flank of the anticline in the north-
ern Black Hills and extend north and northeast to the Great Plains.
The headwaters of these watersheds originate in the Precambrian core
and the creeks flow across outcrops of the Paleozoic and Mesozoic
sedimentary rocks and on to the Great Plains.
Stratigraphy
The Precarabrian rocks in the northern Black Hills consist of
metamorphic, igneous, and sedimentary rocks with a total stratigraphic
thickness of about 600 meters (2,000 feet) (Figure 6). The oldest
formations are the Poorman and the Homestake (Slaughter, 1968), which
are ankeritic carbonates and iron-magnesium carbonates, respectively.
The Homestake Formation is exposed in the Lead-Deadwood area and
contains rich gold-bearing ore deposits. The younger Precambrian
formations are the Ellison, Northwestern, Grizzly, and Flag-Rock, which
are dominantly argillaceous rocks with some quartzites.
The Paleozoic rocks lie unconformably on the Precambrian. The
Deadwood Formation is an interbedded sandstone with a basal quartzite
conglomerate and an upper sandstone and quartzite. These two members
are ore-bearing and locally are often water-bearing. The Deadwood
41
-------
FIGURE 5
GENERAL GEOLOGY OF THE BLACK HILLS
EXPLANATION
PLEISTOCENE
CENOZOIC INTRUSION
UPPER MESOZOIC
(Belle Fourche-Plerre
fms.)
LOWER MESOZOIC
(Spearfish-Mowry
fms.)
CAMBRIAN-PERMIAN
(Deadwood-Mlnrtekahta
fms.)
PRECAMBRIAN
NORMAL FAULT
10 20
0 10 20
' I 1 P
Km.
(FELDMANN AND HEIMLICK, 1980)
42
-------
FIGURE 6
GENERAL STRATIGRAPHIC SECTION OF BLACK HILLS AREA
OUATERNART
E
TERTH
in
3
O
Ul
4
UJ
e
u
PLIOCENE
MIOCENE
OLI60CENE
PALEOCENE
•*
UPPER
LOWER
JURASSIC
TRIASSIC
•» — i
PERMIAN
PENNSTLVANIAN
MISSISSIPPIAN
DEVONIAN \—
ORDOVICIAN
CAMBRIAN
PR£ -CAMBRIAN
FORMATION
SANDS AND 5RAVELS
OSALLALA GROUP
ARIKAREE GROUP
WHITE RIVER SROUP
00 TONGUE RtVER MEMBER
Z t-
3 5 CANNONBALL MEMBER /
o° LUOLOW MEMBER
HELL CREEK FORMATION
FOX HILLS FORMATION
PIERRE SHALE
Sharon Spring* M*m.
NIOBRARA FORMATION
CARLILE FORMATION
Wall Cr»k Sandi
SREENMORN FORMATION
\
O
X.
•I
o
w MOWRT SHALE
Z
2 NEWCASTLE SANDSTONE ,
SKULL CREEK SHALE
< FALL RivER [DAKOTA (?)] 11
«= 2
H!=
Z ._!
MORRISON FORMATION
SUNDANC
L«k !*•«*••'•
E FM »»i«n >«««o.'
SECTION
..•.-. * . ' .. • "": ^
^~=£=r^=^ ^==;-^=^==E
=^=^--=-=^--. ^r^S-^^^
-.-.-.--.-.-.-.-y/.v.jvr.-.y.-.- -.-v:-:: =
: ^^
I —-' ^p^^-^.
SPEARFISN FORMATION ^2^=^^rr^rZ: ' .~^Z= — UL^=r-r-_^rr=I^r::E
OPECHC FORMATION
MINNELUSA FORMATION
PAHA.SAPA (MAOISOMI LIMESTONE
ENGLE*OOO LIMESTONE
WHiTtwOOO (RED RtvERI FORMATION
WINNIPEG FORMATION
DEAOWOOO FORMATION
METAMOAPMIC XX
ISNEOU5 ROCKS
... -. — r
0 - 13
0-30
0 - 150
0 - ISO
0- 130
0-70
/O-IIO
130
8 -SO
370 -600
30-70
120-230
( 8-9 )
(60-110)
90-70
45-75
5-20
50-80
1 -SO
1 - 57
3-t48
\ 0-67
v 0-70
73-140
73-215
15-41
HO -260
90-190
9-20
\ 0-20 1
\ 0-30
1-120
600
(MODIFIED AFTER GRIES. 1974)
43
-------
Formation is 3 to 120 meters (10 to 400 feet) thick. Conformably
overlying the Deadwood Formation is the Winnipeg Formation which is a
shale unit interbedded with siltstone and sandstone. The Winnipeg
Formation is from less than 0.3 to 30 meters (1 to 100 feet) thick.
The Whitewood Dolomite conformably overlies the Winnipeg and consists
of as much as 20 meters (60 feet) of dolomite in the northern Black
Hills. The Englewood Formation, which is a limestone from 9 to 20
meters (30 to 60 feet) thick, grades upward into the overlying Pahasapa
Limestone Formation which is a cavernous dolomite from 90 to 190 meters
(300 to 630 feet) thick. The Pahasapa Limestone is a prolific water-
bearing deposit and can be ore-bearing. The Minnelusa Formation lies
unconformably over the Pahasapa Limestone and consists of an alternat-
ing series of sandstones and dolomites interbedded with minor amounts
of shale and chert. The Minnelusa Formation is between 110 to 260
meters (350 to 850 feet) thick and is a waterbearing formation with
numerous springs which emerge from the outcropping sandstones. The
Minnelusa is overlain by the Opeche Shale Formation, which is 15 to 40
meters (50 to 135 feet) of red silty shale with discontinuous beds of
gypsum or anhydrite.
A relatively thick sequence of Mesozoic sedimentary rocks conform-
ably overlies the Paleozoic section. The Spearfish Formation is 75 to
200 meters (250 to 700 feet) of interbedded red siltstone, shale, and
gypsum. Unconformably overlying the Spearfish is the Middle Jurassic
(180 million to 135 million years old) Gypsum Spring Formation which
consists of interbedded gypsum, siltstone, and shales as much as 38
meters (125 feet) thick. The Sundance Formation lies conformably over
the Gypsum Spring and is an alternating unit of sandstone and shale
which is 75 to 140 meters (250 to 450 feet) thick. The Unkpapa Sand-
stone conformably overlies the Sundance and underlies the Morrison
Formation. The Unkpapa is a fine-grained sandstone up to 15 meters (45
feet) thick while the Morrison is an interbedded shale and sandstone
which reaches thicknesses of 67 meters (220 feet) in some areas.
Unconformably overlying the Morrison is the Inyan Kara Group which
consists of the Lakota Formation and the Fall River Sandstone. These
44
-------
formations are important aquifers in the Belle Fourche vicinity. The
Fall River Sandstone is conformably overlain by a series of Cretaceous
(135 million to 63 million year old) shale and sandstone formations:
Skull Creek, Newcastle Sandstone, Belle Fourche, and Mowry Shales;
Greenhorn Limestone, Carlile Shale, Niobrara Formation, Pierre Shale,
Fox Hills Sandstone, and the Hell Creek Formation. These formations
outcrop on the Great Plains, quite far from the study area.
The Oligocene (36 million to 25 million year old) White River
Group unconformably overlies the Mesozoic rocks and consists of 10 to
200 meters (0 to 600 feet) of clays with local channel fillings and
limestones. Tertiary intrusive rocks are found as dikes, sills, and
laccoliths in the northern Black Hills. The composition varies from
rhyolites to andesite.
The Quaternary (less than 1 million year old) deposits include
alluvial material in streambeds, terrace deposits of gravel, landslide
material, and minor deposits of windblown sand. The Quaternary depos-
its range up to 15 meters (50 feet) in thickness.
Structure
As discussed in the regional geology section, the Paleozoic and
Mesozoic sedimentary rocks have been intruded by a series of west-
northwest trending stocks, laccoliths, and dikes of Tertiary age. The
Tertiary intrusive belt is a well defined belt which crosses the uplift
in a westerly direction. The rocks are steeply inclined on the eastern
side and gently dipping on the western side of the uplift. The Lead-
Deadwood area, at the headwaters of the three watersheds, is one of the
major centers of intrusive activity in the northern Black Hills. The
igneous intrusives are one of the causes of deformation expressed as
doming, monoclines, folding, and vertical faulting within the overlying
sedimentary rocks and Precambrian basement.
The Lead-Deadwood area is a dome which is 19 kilometers (12 miles)
in the east-west direction and 16 kilometers (10 miles) in the north-
south direction and which has approximately 300 meters (1,000 feet) of
structural relief. The central core of the dome is Precambrian rocks
45
-------
surrounded by the Deadwood Formation which dips 5 to 10 degrees from
the dome. The intrusives in forms of sills, laccoliths, and dikes
intrude the dome. Whitewood Creek flows through the heart of the
intrusive activity while Bear Butte Creek flows just to the east and
Spearfish Creek flows to the west of the major intrusive activity.
Occurrence of Gold
Gold deposits in the northern Black Hills occur in three forms:
syngenetic deposits of Precambrian rocks, replacement deposits in the
Tertiary rocks, and placer deposits.
Precambrian Replacement Deposits
Precambrian replacement deposits are syngenetic gold deposits in
the Horaestake Formation in zones of cross-folding. The Homestake Mine
in the Whitewood Creek drainage mines gold from Precambrian replacement
deposits and is the largest gold mine in North America.
Tertiary Ore Deposits
Of primary concern to this study are the Tertiary ore deposits
because of the potential for economically extracting gold from these
deposits by cyanide heap leaching practices. The Tertiary ore deposits
are controlled by the orientation and abundance of vertical faults and
fractures. These "verticals" served as conduits for the upward move-
ment of hydrothermal fluids. The resultant interaction between these
fluids and the wall rock of the Deadwood Formation or the Pahasapa
Limestone was a replacement process in which solutions dissolved,
altered, and introduced minerals. The ore deposits usually consist of
replacement bodies along bedding planes and along the verticals (DeWitt
et al., 1986). In the Portland mining district, the vertical system is
oriented north-northeast while in the Ruby Basin raining district, they
are oriented in a north-northwest system. The ore bodies found at
intersections of verticals often are large bodies of high-grade ore.
Ore deposits in the Lead-Deadwood area are formed by replacement
along flat channelways and along vertical faults and fractures in the
Deadwood Formation and Pahasapa Limestone (Shapiro and Gries, 1970).
46
-------
Replacement deposits occur in dolomitic horizons localized by high-
angle fractures which provide access for ore-forming solutions. The
ore deposits occur in the lower and upper contact zones of the Deadwood
Formation. The lower contact zone is in contact with the Precambrian
rocks (Figure 7). The upper contact zone is 5 meters (15 feet) below
the Scolithus Sandstone facias. The replacement ore bodies in both the
upper and lower contact zones range from 1 to 6 meters (3 to 20 feet)
thick. The deposits are elongated and parallel to the strike of the
verticals which are related to major fracture systems. Deposits in the
Ruby Basin raining district are in the lower contact zone while deposits
in the Portland raining district are in the upper contact zone as well
as in the lower contact zone. The replacement deposits are found in
the Pahasapa Limestone in the Ragged Top district. The replacements in
the Pahasapa Limestone are irregularly shaped lenses and pods.
Two types of ore are found in this area: the primary or blue
ores, and the weathered or brown ores. The brown ores have been
oxidized so the gold and silver is easily extracted. The primary ores
are unoxidized and extraction is more difficult. The blue ores are
silicious zones in dolomitic beds of the Deadwood Formation. The ores
contain quartz and pyrite with minor amounts of arsenopyrite, sylvan-
ite, and possibly other telluride minerals (Shapiro and Cries, 1970).
The secondary ores are primarily a product of the primary ores and a
secondary suite of limonite, gypsum, kaolinite, pyrolusite, and minor
amounts of wulfenite (Shapiro and Cries, 1970).
The Pahasapa Limestone deposits consist primarily of randomly
oriented and mineralized fractures and massive breccia which have been
silicified. The mineralogy of the ore deposits includes silicified
masses of Pahapasa Limestone containing quartz, chalcedony, minor
auriferous pyrite and some telluride minerals (Shapiro and Cries,
1970).
Placer Deposits
Placer gold deposits in the Black Hills have been found in pres-
ent-day streambeds, Tertiary gravel deposits, and Cambrian sandstones.
47
-------
FIGURE 7
STRATIGRAPHIC SECTION SHOWING LOCATION OF UPPER AND
LOWER CONTACT ZONE IN DEAOWOOD FORMATION
, ,
"Z.
<
J«
K
V.
V.
*~
*~
1— *
i
C"""
2
t—t
—
<
-J
/ / /
/ / /
/ / /
/ / /
1
1
— — 1 — 1 — | — 1 — -
|— 1 — — — 1
/ / / / /
1 / / / / _/
/ / / / /
smliS
:r^_r^i-jr^_i~T_i
til ii
i t i
XX X X x
X X X x
x * x x x
x* x^x *
xx*x"xX*
* X XT ^ x
1 1
•^iir-./c/^.^.^c'^
—
/ <=> / 0 /<=> ^
~ ~ " I_
/ » /« /«
<=• / <=> / o / <=
///////
///////
V, £?
~t?~*y*~^^2£r?Z*7
PAHASAPA (Cp)
ei*r*T TTTjnnri ^Po^
WHITEWOOD (Ow)
Roughlock (Or)
WINNIPEG
Ice Box (Oi)
Scolithus
CUPPER
^MEMBER
Finlander
DEADWOOD (6d)
MIDDLE
ric-MiiiiK.
LOWER
MEMBER
PRECAMBRIAN (P£
limestone, dolomite (upper
portion erroded)
.
1 irnes tone
dolomite
siltstone
green shale
sandstone and quartzite
, , .
sandstone, snaJ.e«& dolomite
*> "UPPER
, . fc . > CONTACT"
porphyritxc ter^ZQNZ
tiary intrusive<^
sandstone
shale, limestone,
dolomite, intra-
fonnational congl.
basal qztt. and "LOWER
congl. CONTACT"
7ONT
schist & iron formation
(MODIFIED AFTER KULIK.1965)
48
-------
The sources of these placer deposits are the Homestake and Deadwood
Formations (Carpenter, 1889). The Whitewood Creek placer deposit is
the primary deposit in the study area, although some minor placer
deposits occur in both Spearfish and Bear Butte Creeks. The gold is
concentrated in gravel beds and lenses ranging from 1 to 6 meters (2 to
20 feet) thick. Most operations to exploit placer deposits have been
discontinued because of marginal profits or adverse environmental
impacts on the stream (DeWitt et al., 1986).
Ore Deposits Suitable for Heap Leach Processing
As discussed previously, gold occurs in several types of ores in
the northern Black Hills. The ore associated with Tertiary intrusives
and found in the Paleozoic host rocks is of primary importance. These
precious-metal-rich replacement and vein deposits are suitable for heap
leaching. The basic criterion for selecting an ore suitable for gold
and silver heap-leaching is that sufficient ore with profitable con-
centrations of gold and silver can be defined. Weathered and oxidized
ores are the most suitable for leaching. Ores that contain organic
carbon are not suitable for heap-leaching because the carbon prevents
much of the gold from dissolving and adsorbs dissolved metals before
the leach solutions are recovered. The other requirement is that the
ores have a low sulfide content.
Many of the Tertiary replacement gold and silver deposits in the
Black Hills are located in the Lead-Deadwood area. Areas of high,
medium, and low resource potential for heap-leaching activities are
delineated in Figures 8 and 9, where the precious-metal-rich replace-
ment and vein deposits in the Palezoic rocks are designated as map type
"T". A brief description of each area is provided in Table 4. The ore
deposits from these types of rocks range from 4 to 9 million metric
tons (5 to 10 million short tons) with a gold grade ranging from 1 to 3
grams per metric ton (0.03 to 0.08 troy ounces per short ton).
49
-------
MATCH LINE FIGURE 9
SCALE
1:100.000
LEGEND
OUTLINE OF AREAS WITH HIGH RESOURCE POTENTIAL
FOR GOLD AND SILVER IN MEDIUM TO SMALL VEIN
OR REPLACEMENT DEPOSITS
OUTLINE OF AREAS WITH HIGH RESOURCE POTENTIAL
FOR GOLD AND SILVER IN MEDIUM TO SMALL VEIN
OR REPLACEMENT DEPOSITS
~~ OUTLINE OR AREAS WITH MODERATE RESOURCE
POTENTIAL FOR GOLD AND SILVER IN MEDIUM TO
" SMALL VEIN OR REPLACEMENT DEPOSITS
FIGURE 0
MINERAL RESOURCE POTENTIAL FOR THE
NORTHERN BLACK HILLS-SPEARFISH CREEK
AND WHITEWOOD CREEK
toewiTT et ai.ieae)
-------
ryy{._. .,™
MATCH LINE FIGURE 8
!fsaat^
AREAS OF LOW RESOURCE POTENTIAL FOR GOLD
AND SILVER REPLACEMENT DEPOSITS
OUTLINE OF AREAS WITH HIGH RESOURCE POTENTIAL
FOR GOLD AND SILVER IN MEDIUM TO SMALL .VEIN
OR REPLACEMENT DEPOSITS
OUTLINE OF AREAS WITH MODERATE RESOURCE
POTENTIAL FOR GOLD AND SILVER IN MEDIUM TO
SMALL. VEIN OR REPLACEMENT DEPOSITS
FIGURE 9
MINERAL RESOURCE POTENTIAL FOR THE
NORTHERN BLACK HILLS-BEAR BUTTE CREEK
(DEWITT el al.1966)
MAP UNITS (e.g.T9.V5) ARE DESCRIBED IN TABLE 4
-------
TABLE 4
DESCRIPTION OF GOLD AND SILVER POTENTIAL
IN THE LEAD-DEADWOOD AREA OF THE NORTHERN BLACK HILLS
Map Unit Description
T3 The deposits in the Ragged Top raining district have
moderate potential for precious metals in small vein or
replacement deposits in the Pahasapa Limestone and,
possibly, the underlying strata. Ores in this area
contain the highest ratios of gold to silver in the
northern Black Hills.
T4 The deposits in the main portions of the Portland and
Ruby Basin mining districts have high resource potential
for precious metals in medium-size replacement and vein
deposits contained in the Deadwood Formation. The area
yielded approximately 44 million grams (1,400,000 troy
ounces) of gold and 110 million grams (3,400,000 troy
ounces) of silver from 1887 to the late 1960's.
T5 The deposits in the Garden-Maitland district have
moderate resource potential for precious metals in
small- to medium-size replacement and vein deposits.
T6 Deposits in this area south of Lead, near the Wasp Gold
Mine, have moderate potential for precious metals in
small- to medium-sized replacement and vein deposits in
the Deadwood Formation.
T7 Seven areas have been included in this description area.
The deposits all have moderate potential for precious
metals in medium- to small-size vein or replacement
deposits.
T8 Two small areas in the Lead-Deadwood region have low
potential for small vein or replacement deposits in
Paleozoic rocks.
T9 Two areas have a moderate potential for precious metals
in small vein deposits in Paleozoic rocks. In both
areas the Pahasapa Limestone and older Paleozoic strata
are in contact with various phases of intrusive bodies
creating a favorable geologic setting for vein replace-
ment deposits. No known production exists in these
areas.
(Continued)
52
-------
TABLE 4 (Continued)
Map Unit Description
V2 This deposit in the Richmond Hill area has high poten-
tial for medium-sized disseminated or porphyry deposits
containing precious metals and copper. The deposits are
placement deposits in the Pahasapa Limestone probably
related to one of the stocks in the area.
V3 This deposit in the Ragged Top district has high pote-
ntial for gold and silver in medium to small dissemina-
ted or porphyry deposits. The replacement and vein
deposits are in the Pahasapa Limestone.
VA Several areas are included in this map unit. The areas
have moderate potential for small disseminated or
porphyry deposits containing gold and silver. The areas
contain numerous dikes and irregularly shaped intrusive
bodies that range in composition from rhyobite to
quartz.
V5 This area centered on the Gilt Edge Mine has moderate
potential for precious metals in medium to small dis-
seminated or porphyry deposits.
V6 This area is west of the Galena district and has a high
potential for medium-size disseminated or porphyry
deposits contian precious metals.
T - Precious-metal-rich replacement and vein deposits in Paleozoic
rocks.
V - Precious-metal-rich disseminated and vein deposits in Tertiary
quartz-normative, subalkalic to alkalic igneous rocks.
Source: Modified from Dewitt et al., 1986.
53
-------
Another type of deposit suitable for heap-leaching is also associ-
ated with the Tertiary intrusives. DeWitt et al. (1986) call them the
precious-metal-rich disseminated and vein deposits in Tertiary quartz-
normative, subalkalic to alkalic igneous rocks. The deposits are in
Tertiary rhyolitic stocks and are designated as map type "V" in Figures
8 and 9 and Table 4. These disseminated or porphyry-type deposits are
becoming an increasingly important exploration target because of the
low cost of mining the deposits and the ability to use heap-leaching
techniques to recover the precious metals. These types of deposits,
similar to those at Gilt Edge Mine, probably could produce ore in the
next 5 years (DeWitt et al., 1986). These oxidized ores are amenable
to heap-leaching.
GROUND WATER HYDROLOGY
In the Black Hills area, numerous water-bearing formations ranging
in age from Precambrian to Recent (less than 10,000 years old) have
been identified as generally having good water quality (Fox, 1984).
The principal water bearing units in the study area in the northern
Black Hills are alluvial deposits, sandstone aquifers, and carbonate
aquifers.
The alluvial deposits consist of unconsolidated stream channel
deposits, including gravels, sands, and silts. They typically range in
thickness from 0 to 40 feet or more. The deposits tend to be discon-
tinuous and of limited extent in the northern Black Hills. The aqui-
fers are generally unconfined so the water table fluctuates as the
recharge varies with precipitation, irrigation, and streamflow loss.
The ground water in alluvial deposits is often transmitted through
faults, fractures, and joints to the underlying aquifers (Fox, 1984).
The sandstone aquifers include the Inyan Kara Group (Fall River
Sandstone and Lakota Formations), the Sundance Formation, the Minnelusa
Formation, and the Deadwood Formation (see Figure 6). The aquifers in
the Inyan Kara Group are generally permeable and productive with fair
water quality in the vicinity of its outcrop. Elsewhere, the water is
often saline. Recharge occurs from precipitation, stream losses, and
54
-------
by leakage from the shallow alluvial aquifers. The potentiometric
surface slopes from the Black Hills uplift toward the southeast and
northeast (Todd, 1983). Water quality in the Sundance Formation is
often highly mineralized except near its outcrop where it yields less
mineralized water that is suitable for domestic use (South Dakota State
Geological Survey, 1964). The Minnelusa Formation is predominantly a
white and red calcareous sandstone that ranges from 300 to 880 feet
thick at its outcrop around the Black Hills. Several irrigation wells
in the vicinity obtain good quality water from the Minnelusa Formation.
A well penetrating the Minnelusa near Sturgis initially yielded 250
liters per second (4,000 gallons per minute) which later reduced to
about 50 liters per second (750 gallons per minute) (South Dakota State
Geological Survey, 1964). Aquifers in the Deadwood Formation yield
small to moderate amounts of good to saline water suitable for stock
and domestic supplies.
There are only a few carbonate limestone and dolomite aquifers,
but they generally have a large areal extent and are capable of large
yields where cavernous limestones are located. Ground water in lime-
stone or dolomite aquifers occurs in openings that range from small
pores, joints, and fractures to large caverns. These fractures and
caverns may substantially increase the storage and transmissivities of
the aquifer. The Pahasapa Limestone (equivalent to the Madison) is the
most prolific of these water-bearing deposits and ranges in thickness
from 90 to 200 meters (300 to 650 feet). It is recharged by precipi-
tation, streamflow losses, and by leakage from overlying aquifers. As
surface flow encounters the outcropping Pahasapa Limestone in the
valley bottoms, the streams lose much of their water to the cavernous
limestone. Recharge is estimated to be 170 millimeters (6.8 inches)
per year in this area of the Black Hills (Rahn and Cries, 1973). The
Whitewood Dolomite outcrops in a narrow band around the Black Hills
uplift. The aquifer may furnish water to the overlying Pahasapa
aquifer through leakage if large amounts of water are withdrawn from
the Pahasapa Limestone (Todd, 1983). The Whitewood Dolomite aquifer
contains saline waters and is not used as a source of water.
55
-------
Springs from these aquifers are also an important water supply.
The primary source of the springs is thought to be the Pahasapa Forma-
tion and it is believed that faulting or channeling has allowed the
water to reach the surface. The numerous springs in the area suggest
the possibility of fault zones which would allow artesian water to
migrate to the surface along fault planes.
Table 5 summarizes water quality analyses for selected ground
water wells in the study area. The wells were sampled by the U.S.
Geological Survey (USGS) and are either municipal or domestic wells.
Wells 1, 2, and 3, located in the Spearfish Creek Drainage, (Figure
10) are completed in the Pahasapa Limestone and Deadwood Formation.
Wells 1 and 2 completed in the Pahasapa Limestone exceed the EPA
secondary drinking water criteria for drinking water for manganese.
Well 1 also exceeds EPA secondary criteria for sulphate. Well 3,
completed in the Deadwood Formation exceeds EPA secondary drinking
water criteria for iron and manganese. Wells 4 and 5 are located in
the Whitewood Creek Drainage and were sampled in the alluvium and
Precambrian aquifers. Chromium levels exceeded the EPA Maximum
Containmant Level (MCL) in well 4 while well 5 did not exceed any of
the EPA contaminant levels. In the Bear Butte Creek drainage, one well
was sampled in both the Deadwood and Precambrian aquifers. Neither
analysis exceeded any of the EPA contaminant levels. The water
analyses for wells 2, 3, 5, and 6 indicated a bicarbonate water type.
Well 1 was typed as a calcium-, magnesium-, sulfate-rich water.
Spearfish Creek Watershed
Most of the Spearfish Creek watershed in the northern Black Hills
is deeply incised through carbonate aquifers. According to records of
the South Dakota Department of Water and Natural Resources, the town of
Spearfish uses four municipal wells for part of its water supply.
Three of the wells are completed in the Pahasapa Limestone between
depths of 263 and 329 meters (863 and 1,080 feet). A fourth well is
completed in the Minnelusa Formation. The estimated yield for these
wells is 0.2 to 0.3 liters per second (3 to 5 gallons per minute) per
56
-------
TABLE 5
ANALYSES OF SELECTED GROUND WATER WELLS IN
SPEARFISH CREEK, WHITEWOOD CREEK, AND BEAR BUTTE CREEK WATERSHEDS
Parameter
Aquifer
Date sampled
pH
Bicarbonate, HCO,
Calcium, Ca
Magnesium, Mg
Sodium, Na
Potassium, K
Chloride, Cl
Sulfate, SO^
Arsenic, As
Barium, Ba
Boron, B
Cadmium, Cd
Chromium, Cr
Cobalt, Co
Copper, Cu
Fluoride, F
Iron, Fe
Lead, Pb
Manganese, Mn
Molybdenum, Mo
Nickel, Nl
Silver, Ag
Strontium, Sr
Vanadium, V
Zinc, Zn
Aluminum, Al
Lithium, LI
Selenium, Se
Titanium, Tl
Zirconium, Zr
Uranium, U
Ceslum-144 Total (pCl/L)
Water Use
Drinking Water
Guidelines
(mg/1)
—
—
—
—
—
—
—
E7
250b/
250a/
0,05a/
1
— /
0.01 i
0.05a/
K7
14 4a/
0:5^;4
o.osfj
0.05b/
—
— /
0.053'
—
57
5.0D/
—
— /
0.01
—
—
—
—
—
Spearflsh Creek Watershed
Well No. 1
(rag/1)
Pahasapa
6/1/79
7.30
453
139.0
72.0
231.0
(5.0)
(15) .
(925)°'
(0.0005)
(0.007)
(0.784)
—
(0.004)
(0.002)
(0.002)
—
(0.011)
(0.663)C/
(0.013)
(0.004)
(0.002)
(1.911)
(0.004)
(0.090)
(0.010)
(0.182)
(0.0004)
(0.002)
(0.002)
(0.0045)
30
Domestic
Well No. 2
(mg/1)
Pahasapa
10/29/82
7.8
110
4.4
0.4
37.0
0.60
(0.8)
(5)
—
—
0.02
—
—
—
—
1.9
0.150
0.088C/
—
—
—
—
—
0.042
—
—
—
—
—
—
—
Public
Well No. 3
(rag/1)
Deadwood
5/3/77-8/13/81
7.3-7.5
46-89
10.7-42.3
2.5-9.1
2.0-5.5
0.60
(0.4-3)
(7-12)
(0.004-0.005)
(0.059-0.70)
—
(0.001)
(0.001-0.003)
—
(0.005-0.045)
0.01-0.2 .
(0.290-0.690)
(0.002-0.007)
(0.02-0.07)
—
—
(0.001)
—
—
(0.168-2.43)
—
—
(0.001)
—
—
—
—
Public
Whltewood Creek Watershed
Well No. 4
(mg/1)
Alluvium
12/18/81
—
—
—
—
—
—
—
(1.87)
(0.029)
(0.001)
—
(0.006),
(0.170)°'
—
—
1.87
(0.007)
—
—
(0.001)
—
—
1.450
—
—
(0.003)
—
—
—
—
Public
Well No. 5
(mg/1)
Precambrlan
3/6/58-3/31/81
7.5-7.69
205-246
54.5-61.7
7.8-11.9
1.7-5.98
0.90-1.30
(0-4)
(2-10)
(0.001)
(0.049-0.069)
—
(0.001-0.002)
(0.001-0.01)
—
(0.01)
0.16-0.31
(0.02-0.04)
(0.002-0.012)
(0.20)
—
—
(0.001-0.002)
—
—
(0.77)
—
—
(0.001)
—
—
—
—
Public
Bear Butte Creek Watershed
Well No. 6
(mg/1)
Precambrlan
5/8/79
8.11
279
51.8
25.1
1.0
0.6
(0.3)
(5)
—
—
—
—
—
—
—
0.10
::
—
—
—
—
—
—
—
—
—
—
—
—
—
Public
Deadwood
11/10/81
5.29
—
0.05
0.05
0.20
—
(0.1)
(0.08)
—
0.002
—
0.001
—
0.003
0.01
0.10
0.01
10
0.001
0.01
—
—
0.001
0.006
0.003
—
0.004
—
—
—
—
—
Public
a/
b/
c/
EPA MCL.
EPA Secondary Criteria (not enforceable).
Samples exceed EPA standards or guidelines.
() Indicates total metals (unflltered samples); other numbers represent dissolved metals (filtered samples).
Source: EPA STORET Data Base.
-------
FIGURE 10
SELECTED GROUND WATER
WELL LOCATIONS
1 WELL LOCATION
(EPA STORET DATA BASE)
-------
foot of drawdown. Summer residents along Spearfish Creek and the small
developed areas near Deer Mountain and Terry Peak Ski Area generally
have private ground water wells for domestic use. The Terry Peak Ski
Area has one well completed in the Deadwood which it uses for snow-
making. Immediately north of Terry Peak an abandoned mine shaft
containing water of good quality is used as a community water supply.
Whitewood Creek Drainage
Ground waters in the upper reaches of the Whitewood Creek drainage
where the drainage crosses the Precambrian and Cambrian bedrock occur
predominantly in shallow alluvial deposits. The Deadwood Formation is
also a productive aquifer in this area. Water is supplied to the town
of Lead by the Homes take Mining Company from a series of surface
springs. The town of Whitewood has two wells completed in the
Minnelusa Formation. Diamond Springs and the Cutting Mine Shaft
provide municipal water supply for the town of Deadwood, according to
records of the South Dakota Department of Water and Natural Resources.
Bear Butte Creek Drainage
The water supply for the town of Sturgis is provided by four wells
which are dually completed in the Pahasapa Limestone and the Minnelusa
Formation.
SURFACE WATER HYDROLOGY
The northern Black Hills lie in the Belle Fourche River system,
which is part of the larger Cheyenne River System. The Cheyenne River
between the Belle Fourche River confluence and the Missouri River ranks
as one of the State of South Dakota's worst-quality river segments
(U.S. Environmental Protection Agency, 1985). Severe suspended solids
problems resulting from past mining practices have been traced to soil
erosion and mine tailings in the Black Hills. The river has been found
to contain high concentrations of sulfate, arsenic, barium, beryllium,
chromium, iron, manganese, lead, nickel, and sodium. Many of these
59
-------
substances are found naturally in the area's shale formations, although
some are undoubtedly associated with past mining operations. Water
quality has improved considerably since active tailings discharge was
discontinued in 1977.
Belle Fourche River
The Belle Fourche River on the Missouri Plateau upstream from the
town of Belle Fourche has a drainage basin of 8,420 square kilometers
(3,250 square miles) (Darton, 1909). There are three USGS gauging
stations on the Belle Fourche River between the town of Belle Fourche
and the confluence with Bear Butte Creek (Figure 11). The average
annual discharge of the river upstream from the study area at the
Wyoming-South Dakota state line is 2.59 cubic meters per second (91.4
cubic feet per second) (cfs)) (Table 6). Downstream at Sturgis, the
average discharge is 7.90 cubic meters per second (279 cfs) (Hoffman et
al. , 1984). Periods of high flow occur in May and June and correspond
to periods of peak precipitation. Low flow occurs in the late fall and
winter months. Water quality in the Belle Fourche River has improved
since 1977, largely because Horaestake Mine ceased active tailings
discharge (Fox Consultants, Inc., 1984). Nonetheless, water quality
data collected in 1983 by the U.S. Geological Survey and by Fox Consul-
tants, Inc. (1984) indicate that the Belle Fourche River carries
elevated concentrations of sulfate, iron, and manganese derived from
both the natural environment and from mine tailings and that EPA
secondary drinking water criteria are exceeded for iron and sulfate.
Trace concentrations of zinc, nickel, and copper also occur and appear
to be derived from the mine tailings (Fox Consultants, Inc., 1984).
Recent sampling by the U.S. Geological Survey (Hoffman et al., 1984)
indicated that total cyanide was detectable in the Belle Fourche River
at concentrations ranging from 0.02 to 0.33 milligrams per liter (rag/1)
during March, April, and May of 1984 but were below detection (less
than 0.01 mg/1) during the remainder of 1984. These measurements were
made prior to the construction of Horaestake's cyanide treatment facili-
ty (F.D. Fox, Homestake Mining Company, personal communication, 1986).
A portion of the Belle Fourche River and a tributary (Whitewood Creek)
60
-------
FIGURE 11
SURFACE WATER RESOURCES
TO THE TOWN OF BELLE FOURCHE
SCALE
Km
USQS GAUGING STATIONS
USGS WATER QUALITY
SAMPLING POINTS
{Fox Consultants.Inc..1984)
HYPOTHETICAL MINING SITE
-------
TABLE 6
FLOW RATES OF SELECTED STREAMS IN THE NORTHERN BLACK HILLS
Spearflsh Creek at
Spearflsh '
Whlteuood Cceek at
Deaduood
Whltewood Craek above
Whlteuood
Vhlteuood Creek near
Whltewood '
Whitewood Creak
above Vale
Bear Butte Creek
at Galena
Bear Butte Craek
at Sturgis8'
Belle Fourche Rtver
at Wyoming State
Line*'
Belle Fourche Rlvar
near Frultdale
Belle Fourche giver
near Sturgls
a/
b/
c/
d/
e/
f/
g/
h/
I/
M
k/
I/
Mean
Mean Monthly Discharge In mq/s (cfs In parenthesis) Annual
Oct. Nov. Dec. Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sept. Discharge
1.79 1.52 1.17 1.60 1.40 1.64 1.98 3.00 4.02 1.92 1.71 1.32 1.50 .,
(63.3) (53.6) (41.2) (56.4) (49.6) (57.8) (69.9) (106) (142) (67.8) (60.3) (46.5) (53.1) '
0.470 0.391 0.251 0.374 0.351 0.521 1.13 6.03 2.89 0.833 0.541 0.416 1.19 ,,
(16.6) (13.8) (8.88) (13.2) (12.4) (18.4) (40.0) (213) (102) (29.4) (19.1) (14.7) (42.0) '
0.552 0.456 0.292 0.337 0.396 0.580 1.20 3.65 2.86 0.883 0.500 0.416 1.01 ,,
(19.5) (16.1) (10.3) (11.9) (14.0) (20.5) (42.4) (129) (101) (31.2) (17.5) (14.7) (35.7)
0.625 0.566 0.328 0.405 0.473 0.626 1.38 3.82 2.38 0.912 0.524 0.433 1.04 ,/
(22.1) (20.0) (11.6) (14.3) (16.7) (22.1) (48.9) (135) (84.2) (32.2) (18.5) (15.3) (36. 8)1'
0.801 0.462 0.326 0.450 0.569 0.861 1.45 4.25 4.42 0.994 0.513 0.323 1.28 .,
(28.3) (16.3) (11.5) (15.9) (20.1) (30.4) (51.1) (150) (156) (35.1) (18.1) (11.4) (45. 3)1'
. 0.527 0.82 0.051 0.034
ND ND ND ND NO NO (18.6) (29.0) (1.79) (1.20) ND ND ND
0.118 0.176 0.154 0.142 0.453 0.303 0.345 1.28 6.40 0.634 0.174 0.069 0.379 t/
(4.15) (6.23) (5.43) (5.02) (16.0) (10.7) (12.2) (45.2) (226) (22.4) (6.15) (2.42) (13.4)K'
0.722 0.614 0.317 0.518 0.883 4.05 2.57 10.1 23.0 3.09 1.25 0.580 2.59 h/
(25.5) (21.7) (11.2) (18.3) (31.2) (143) (90.7) (355) (812) (109) (44.1) (20.5) (91.4) '
0.177 0.171 0.112 0.117 0.092 0.092 0.107 8.58 27.6 0.479 0.294 0.244 2.50
(6.26) (6.05) (3.97) (4.14) (3.25) (3.24) (3.77) (303) (974) (16.9) (10.4) (8.62) (88.4)
2.27 1.52 0.629 0.603 1.79 1.75 2.59 28.1 63.0 10.7 10.1 9.12 7.90 ,
(80.1) (53.8) (22.2) (21.3) (63.2) (61.9) (91.4) (992) (2,225)(377) (356) (322) (279)
Maximum
Instantaneous
Discharge
120 b/
(4,240)D/
75.3 .
(2,660)C/
19.4 .
(684)d/
86.3 ,
(3,050)C/
30.3 .,
(l,070)d/
538
(19,000)
204 .,
(7.220)1'
125 h/
(4,400)"'
360 ,
(12,700)e/
1,030 .
(36,400)
Minimum
Instantaneous
Discharge
h/
ob/
0.099 ,
(3.5)C/
0.25 d/
(9.0)d/
0.11 ,
(4.0)C/
0.22 .,
(7.8)d/
\l
0J/
if/
ok/
v /
ob/
o/
oe/
e/
0 '
From Hoffman et al., 1984
Period of Record: 38 years
Period of Record: 3 years
Period of Record: 2 years
Period of Record: 39 years
From U.S. Geological Survey, 1972
From U.S. Geological Survey, 1969
ND - No Data
Schuarz et al., 1975
Period of Record: 4 years
Period of Record: 27 years
Period of Record: I year
-------
were placed on the National Priorities List for evaluation under CERCLA
because of water quality degradation resulting from past mining activi-
ties.
The beneficial uses designated by the State of South Dakota for
the Belle Fourche River from the Wyoming border to the Cheyenne River
are warm water permanent fish life propagation, immersion recreation,
and limited contact recreation. In addition, all of the State's waters
are designed as suitable for wildlife propagation and stock watering,
and irrigation (see Table 7 for a list of criteria used to determine
suitable uses).
All three streams which were evaluated for impacts from potential
cyanide heap leach operations are tributary to the Belle Fourche River.
Spearfish Creek empties into the Redwater River, which flows into the
Belle Fourche approximately 260 kilometers (160 miles) upstream from
its confluence with the Cheyenne River. Whitewood and Bear Butte
Creeks both empty directly into the Belle Fourche approximately 210 and
160 kilometers (130 and 100 miles), respectively, upstream from the
confluence of the Belle Fourche River with the Cheyenne River.
Spearfish Creek Watershed
Spearfish Creek originates in the Black Hills at an elevation of
about 2,000 meters (6,500 feet) and flows 56 kilometers (35 miles)
northeast past the town of Spearfish before joining the Redwater River
at an elevation of 1,000 meters (3,300 feet). The larger Redwater
River flows another 16 kilometers (10 miles) across the Belle Fourche
River flood plains before joining the Belle Fourche River just upstream
from the town of Belle Fourche.
Spearfish Creek drains part of a high limestone plateau and its
adjacent slopes in the northern Black Hills. This 12,000-hectare
(30,000-acre) drainage basin is the largest of the three streams chosen
for study in this project. Its principal tributary is Little Spearfish
Creek, which carries about one-tenth the flow of Spearfish Creek.
Spearfish Creek itself is the largest tributary to the Redwater River
and has an average annual discharge over a 38-year period of 1.5 cubic
63
-------
TABLE 7
STATE OF SOUTH DAKOTA
SURFACE WATER QUALITY STANDARDS ,
FOR STREAMS IN THE BLACK HILLS STUDY AREA
g
Parameter
Alkalinity, Total/CaCP3
Arsenic
Barium
Cadmium
Chloride
0.
ex
3
U
2
a
3
U
7j
n
V
a
1
.05
1.0
0.01
250
S<->
a
s y
E 2.
S.2
O.
(j
§ in
•0 JO
S £
2
—
—
—
100
.H -H
SS
•H bo
bo co
n a.
CO O
e Li
a
3 <2
S ^j
•0 J3
rH n
3 M-l
3
—
—
—
—
*~ w
C3 •<-<
a bo
B a
C a
« 0
ex M
ex
u
3 «M
fid «H
EJ:
n
5 iw
4
—
—
—
—
a>
«*-t
•H
•H
S C
V a
>M O
Sw5
S e u
« a
B p ex
EGO
3 elcl
5
—
—
—
—
o
§«•>
a
•H bo
bo CO
u ex
of O
i u
ex
M
a) CD
<-> IM
0 •<
S ^1
es
M -H
3 *M
6
—
—
—
—
§
•H
U
CO
1)
h
O
2
g
vl
0)
Li
M
7
—
—
—
—
u
u
3
a
o a
U 0
•a "
01 a
U 01
•H M
6 U
•H 0)
J U
8
..
—
—
—
—
g M
0) -r^
tO 14
a a)
ex u
ex
«^
"M 0
•H iJ
(H 01
•-4 0
3 a
9
750
—
—
—
—
o
CD .
U u
co a
a
0 1
iJ U*>
"^ -9"
10
_.
—
—
—
—
it
CO
3
•a
5
T3
01
U
|
<§
n
..
—
—
—
—
Chlorine, Total Residual
Chromium
Collforra/lOOml
Collforra Fecal/lOOml
Conductivity
ralcromhos/cm @ 25°C
Cyanide, Free
Cyanide, Total
Hydrogen Sulflde
Lead
Mercury
Nitrogen, Nitrates aa N
Nitrogen, Ammonia as N
Oxygen, Dissolved
DO - In spawning area
pll (standard units)
Polychlorlnated blphenyls
Selenium
Sodium, absorption ratio
Solids, suspended
Solids, Total Dissolved
Sulfate
Temperature (°C)
Temperature (°F)
.02
.02
.02
.02
.05
5000
200
1000
—
—
—
.05
.002
10
—
—
—
6-9
.005
.02
.002
—
—
—
.02
6.0
7.0
6.6-
8.6
.005
.02
.002
—
—
—
.02
5.0
—
6.5-
8.5
.005
.02
.002
—
—
—
.04
5.0
6.0
6.5-
9.0
.005
.02
.002
—
—
—
.04
5.0
—
6.3-
9.0
4000 2500
50
5.0
5.5-
8.3
5.0
6-9
6.0
9.5
.000001 .000001 .000001 .000001 —
.01
10
1000
500
30
18
65
90
24
75
90
27
80
90
32
90
2500
a/
All units In mg/1 unless otherwise Indicated.
Source: Arttcle 74:03 Water Pollution Program, State of South Dakota.
-------
meters per second (53.1 cfs) at the USGS gauging station at Spearfish
(see Table 6). The maximum recorded discharge at Spearfish of 120
cubic meters per second (4,240 cfs) occurred on May 15, 1965. His-
torically, yearly peak flows occur in May and June in response to high
precipitation, with low flows occurring in late fall and winter.
Average yearly water yield is about 4.4 million cubic meters (36,000
acre-feet) (U.S. Forest Service, 1976). A considerable reduction in
flow occurs in Spearfish Creek about 5 kilometers (3 miles) upstream
from the town of Spearfish. The stream in this segment was completely
dry during a 1986 site visit by the authors in July of 1986. Much of
the flow is diverted by the Homestake Mining Company and used for power
generation. However, even when the water was not diverted, most of the
water flowed underground into the limestone outcrops in the area. Flow
resumes immediately upstream from the fish hatchery near the town of
Spearfish.
Water in Spearfish Creek is of the calcium carbonate type and is
moderately alkaline (U.S. Geological Survey, 1983). Trace metal con-
centrations are generally below detection and cyanide was not detected
in either sediment or water samples (Table 8) (U.S. Geological Survey,
1983). Previous water quality studies available in the EPA STORET data
base indicate that there have been periods of decreased water quality.
Some mining has historically occurred in the Spearfish Creek drainage.
Beneficial use designations have been made by the State of South
Dakota based on the ability of the stream to support communities of
aquatic organisms, the quantity or quality of the water, and uses made
of the water. Suitable uses on Spearfish Creek as designated by the
State of South Dakota are domestic water supply, cold water permanent
fish life propagation, immersion recreation, and limited contact
recreation, except in the reach of the power plant diversion where the
use designation is for cold water marginal fish life propagation and
limited contact recreation.
Approximately 8.50 cubic meters per second (300 cfs) in surface
water rights have been claimed for power, fish culture, municipal,
irrigation, and commercial use according to records of the South Dakota
65
-------
TABLE 8
SUMMARY OF WATER QUALITY AND SEDIMENT DATA FOR
SPEARFISH CREEK
Water
EC (umhos per cm)
pH (standard units)
Calcium
Magnesium
Sodium
Potassium
Alkalinity
Sulfate
Chloride
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Zinc
Cyanide
Dissolved
(mg/1)
710
8.2
100
36
5.0
1.5
233
150
7.2
-------
Department of Water and Natural Resources. The Homestake Mining
Company is a primary user of surface water in the Spearfish Creek
drainage and diverts water for power generation and mining, and
supplies treated water for municipal use to the town of Lead and a
portion of Deadwood. The town of Spearfish diverts water from
Spearfish Creek for municipal use in addition to water supplied from
deep water wells. (See the discussion in the ground water section.)
Upstream from the town of Spearfish, the fish hatchery has water rights
on Spearfish Creek. Further downstream on the plains north of the
Black Hills, Spearfish Creek is used primarily for irrigation.
The site chosen for the hypothetical mining operation is located
in the headwaters of Raspberry Gulch (see Figure 11). The gulch is
ephemeral, flowing only in response to snowmelt and precipitation
events. Raspberry Gulch is located in steep terrain with its origin at
an elevation of about 1,800 meters (6,000 feet). Its slope is about 10
percent over its 2.4 kilometer (1.5-mile) course. Water quality data
in the gulch is lacking, but is expected to be of high quality except
for minor amounts of suspended sediment. No water rights were identi-
fied for these gulches.
Whitewood Creek Watershed
Whitewood Creek is a tributary of the Belle Fourche River, flowing
northeast from its source in the Black Hills past the Horaestake Mine
and the towns of Lead, Deadwood, and Whitewood before emerging onto the
flood plain of the Belle Fourche River on the Missouri Plateau. The
majority of the flow in Whitewood Creek during low flow periods,
originates as effluent from the Homestake Mine. Its headwaters are
located at an elevation of 1,900 meters (6,200 feet) and the creek
flows about 50 kilometers (30 miles) before entering the Belle Fourche
River at an elevation of 4,500 kilometers (2,800 feet).
Whitewood Creek is a stream of moderate volume draining 5,700
hectares (14,000 acres) in a long narrow basin in the Black Hills.
From upstream to downstream, there are four USGS gauging stations: at
Deadwood, above Whitewood, near Whitewood, and above Vale. These
67
-------
stations have only been in operation for 2 or 3 years. From upstream
to downstream, the recorded average annual discharges for 1984 were 1.2
cubic meters per second (42.0 cfs), 1.01 cubic meters per second (35.7
cfs), 1.04 cubic meters per second (36.8 cfs), and 1.28 cubic meters
per second (45.3 cfs) (see Table 6). Average annual water yield is
about 4.3 million cubic meters (3,500 acre-feet) (U.S. Forest Service,
1976). In addition to natural flows, Whitewood Greek receives treated
water from the gold mine at Lead, which is supplied in part by an
aqueduct from Spearfish Creek. Average monthly flows for the period of
record were highest in May and June in response to precipitation. Flow
averaged 6.03 cubic meters per second (213 cfs) in Deadwood and de-
creased to an average of 4.42 cubic meters per second (156 cfs) at the
mouth (Hoffman et al., 1984). The flow decrease in this reach is due
to both water withdrawls and losses to the groundwater. Low flows
occured in the winter months and averaged about 0.28 cubic meters per
second (10 cfs).
Tailings have been deposited in Whitewood Creek for about 100
years until 1977. Prior to the initiation of tailings discharge,
Whitewood Creek was a small stream with insufficient capacity to move
large quantities of sediment. In adjustment to the introduction of
vast tonnages of tailings sediments into the stream, the length of the
stream channel diminished, primarily through meander abandonment,
thereby increasing the stream gradient and thus the stream sediment
carrying capacity. As the meanders were being abandoned, the stream
began a period of down-cutting. However, this was limited by resistant
coarse alluvial deposits and shale outcrops that form the stream bed.
As a result, Whitewood Creek became a braided channel characterized by
shifting small bars and small unstable islands. The tailings deposits
are up to 5 meters (15 feet) thick. It has been speculated (Fox
Consultants, Inc., 1984) that the creek is at least partially sealed
off from the underlying aquifer by tailings. Whitewood Creek is one of
the few streams flowing out of the Black Hills that does not become
68
-------
intermittent upon crossing the Paleozoic outcrop belt. In the late
1800's, sink holes were plugged to inhibit leakage to the ground water
(P. Greese, South Dakota School of Mines, personal communication,
1986).
Whitewood Greek is generally slightly alkaline and of a calcium
carbonate type. Results of the USGS sampling program in 1983 (Fox
Consultants, Inc., 1984) indicate that the mine tailings along White-
wood Creek have introduced trace elements into surface waters (Table
9). Except for sulfate, no parameters were found in concentrations in
excess of recommended water quality criteria for livestock and irriga-
tion. However, EPA drinking water standards and aquatic life standards
were exceeded in some samples for arsenic, cadmium, chromium, iron,
lead, manganese, mercury, and cyanide. Although cyanide was not
detected in every sample, sediment sampling data indicated that cyanide
was present at a level of 1 to 2 milligrams per kilogram (rag/kg).
Although water quality has improved considerably since the cessation in
1977 of tailings disposal in the creek, water quality has not improved
to the levels observed in the less-disturbed Spearfish Creek.
Whitewood Creek has been classified by the South Dakota Department
of Water and Natural Resources into four separate beneficial use
categories. The segment from its confluence with the Belle Fourche
River to Interstate 90 has been designated a warm water, semipermanent
fish life propagation and limited contact recreation stream. The
semipermanent fish life designation could be due to periodic low flows
caused by irrigation withdrawals on the plains during the summer
months. The segment of Whitewood Creek upstream from Interstate 90 to
Gold Run Creek has been designated as a cold water, marginal fish life
propagation, immersion and limited contact recreation stream. The
segment from Gold Run Creek to Lead has been designated for cold water
permanent fish life propagation, immersion recreation and limited
contact recreation. Above Lead, the stream is designated for cold
water permanent fish life propagation and limited contact recreation.
69
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TABLE 9
SUMMARY OF WATER QUALITY AND SEDIMENT DATA FOR WHITEWOOD CREEK
Whltewood Creek
Above Lead
Flow m /s
(cfs)
pH (standard units)
EC (umhos per cm)
Calcium
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Magnesium
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Sodium
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Potassium
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Alkalinity (mg/1)
Sulfate (mg/1)
Chloride (mg/1)
Arsenic
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Cadmium
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
<4.0-36.0
<0.010
<0.001-0.047
<0.010
<0.010
Whitewood Creek
Above Whitewood
0.40-12.1
(14-426)
7.1-9.3
190-932
26-120
36-150
19,900
8.2-54
13-60
3,800
3.8-54
4.8-60
330
1.9-13
3.3-35
890
85-274
17-380
<3-34
<10-27
0.036-1.400
650
<0.001-0.007
<0.001-0.025
5
Whitewood Creek
Near Whitewood
0.34-7.62
(12-269)
6.7-8.7
388-1100
47-150
57-150
21,200
16-57
19-56
3,600
14-49
12-53
240
3.4-11
4.1-11
850
105-186
90-510
6.0-20
0.011-0.062
0.038-0.058
900
<0.001-0.005
<0.001-0.009
6
Whitewood Creek
Above Vale
8.1 (lab)
1320 (lab)
150
180
28,400
63
80
2,800
60
71
270
12
14
760
181
540
14
0.056
0.120
360
<0.001
0.002
3
(Continued)
-------
TABLE 9 (Continued)
Chromium
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Copper
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Iron
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Lead
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Manganese
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Mercury
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Nickel
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Whitewood Creek
Above Lead
<0.010
<0.010-0.064
<0.050
<0.050
<0.050-0.350
<0.050-5.9
<0.050
<0.050
<0.010-0.020
<0.010-0.405
<0.0002-0.0014
<0.0002-0.018
<0.040
<0.040
Whitewood Creek
Above Whitewood
<0.010
<0.010-0.480
4
<0.050-0.073
<0.050-1.100
99
<0.050-0.067
0.880-202
28,500
<0.005-0.008
<0.005-2.700
18
0.054-0.750
0.170-6.700
730
<0.0002
<0.0002-0.Oil
0.22
<0.040
<0.040-0.140
17
Whitewood Creek
Near Whitewood
<0.010
<0.010-0.016
3
<0.050-0.110
<0.050-0.200
67
<0.050-0.088
0.500-13.200
25,800
<0.005-0.050
<0.005-0.056
18
0.052-0.250
0.110-0.700
610
<0.0002
<0.0002-0.0005
0.24
<0.040
<0.040
11
Whitewood Creek
Above Vale
<0.010
<0.010
4
<0.050
<0.050
130
<0.050
1.200
18,400
<0.005
<0.005
17
0.240
0.320
740
<0.0002
<0.0002
0.42
<0.040
<0.040
14
(Continued)
-------
TABLE 9 (Continued)
Selenium
dissolved (rag/1)
total (mg/1)
sediment (mg/kg)
Silver
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Zinc
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Cyanide
dissolved (mg/1)
total (mg/1)
sediment (mg/kg)
Whitewood Creek
Above Lead
<0.020
<0.020
<0.010
<0.010
<0.010
<0.010-0.040
<0.010
<0.010
Whitewood Creek
Above Whitewood
<0.002
<0. 002-0. 048
<0.010
<0. 010-0. 056
<0.010
0.024-4.000
100
<0. 01-0. 24
0.02-0.37
2
Whitewood Creek
Near Whitewood
<0. 002-0. 007
<0. 002-0. 004
<0.010
<0.010
<0.010
<0. 010-0. 095
66
<0. 01-0. 15
<0. 01-0. 22
1
Whitewood Creek
Above Vale
<0.020
<0.020
<0.010
<0.010
<0.010
0.018
100
<0.01
<0.01
1
Source: U.S. Geological Survey, 1983; Fox Consultants, Inc., 1984.
-------
Currently, there are about 14 cubic meters per second (500 cfs)
claimed in surface water rights on Whitewood Creek, according to
records of the South Dakota Department of Water and Natural Resources.
Uses for which these water rights were obtained include mining (for the
Homestake Mining Company) and irrigation on the plains north of the
Black Hills. The majority of the water rights in this watershed are
for irrigation. No use of Whitewood Creek for municipal purposes was
identified.
The site chosen for the hypothetical mining operation is located
in the headwaters of Yellow Creek, a tributary to Whitewood Creek
located near Lead (see Figure 11). Yellow Creek originates at an
elevation of about 1,800 meters (5,800 feet) and traverses about 4
kilometers (2.5 miles) with a slope of about 5 percent. Although
Yellow Creek is perennial, it probably has a small base flow with the
highest flows occurring in response to precipitation. No water quality
data are available for Yellow Creek. However, since Yellow Creek was
the site of a large mining operation during the early 1900's, water
quality may exhibit slightly elevated concentrations of suspended
solids and trace metals.
Bear Butte Creek Watershed
Bear Butte Creek has a drainage area of 15,000 hectares (37,050
acres) (U.S. Forest Service, 1976). It originates at an elevation of
about 1,800 meters (6,000 feet) in the Black Hills, flows past the town
of Sturgis at the edge of Black Hills, and empties into the Belle
Fourche River at an elevation of about 790 meters (2,600 feet). It is
about 60 kilometers (40 miles) in length. West of Sturgis, flow in
Bear Butte Creek sinks into the Pahasapa Limestone. Flow then emerges
near Sturgis and continues to the mouth. The only two USGS gauging
stations on Bear Butte Creek, near Galena and at Sturgis, have been
discontinued. However, the recorded yearly average at Sturgis over a
27-year period was 0.379 cubic meters per second (13.4 cfs) (see Table
6). The discharge of 540 cubic meters per second (19,000 cfs) at
Galena during the 1972 flood exceeded the 100-year flood (Schwarz et
al., 1975). Near Sturgis, the discharge during the 1972 flood was 204
73
-------
cubic meters per second (7,220 cfs) which was equivalent to a 40-year
flood (Schwarz et al., 1975). Peak annual flows generally occur in May
and June in response to precipitation events. There are occasional
periods of no flow which generally occur in late fall and winter months
(U.S. Geological Survey, 1972). Average annual yield from Bear Butte
Creek is about 2.7 million cubic meters (2,223 acre-feet) (U.S. Forest
Service, 1976).
Water quality data on Bear Butte Creek are limited. The EPA
STORET Data Base contains limited water quality data on Bear Butte
Creek near Sturgis and above Boulder Creek (see Table 10). The analy-
ses near Sturgis were performed from April 1960 thru May 1962 on sever-
al parameters. Of the parameters analyzed, only sulfate exceeded the
EPA drinking water standards. At the Bear Butte Creek station above
Boulder Creek, pH, conductivity, dissolved oxygen, and alkalinity were
the only parameters analyzed.
More recent data collected in conjunction with the Gilt Edge Mine
Project indicate that the slightly acidic water is generally of good
quality, although some adverse impacts result from a number of aband-
oned mine workings, waste dumps, and tailings piles in the drainage.
Arsenic and copper are slightly elevated although levels are still
below criteria recommended for aquatic biota. Iron was also elevated
and exceeded levels recommended for aquatic biota. Cyanide was below
detection limits. South Dakota has designated the segment from the
confluence with the Belle Fourche River to Highway 385 as suitable for
cold water marginal fish life propagation and limited contact recrea-
tion. Upstream from Highway 385, the use designation improves to cold
water permanent fish life propagation and limited contact recreation.
About 25 cubic meters per second (870 cfs) on Bear Butte Creek are
claimed in surface water rights for irrigation, recreation, fish
culture, municipal use, and milling according to records of the South
Dakota Department of Water and Natural Resources. Most of this water
is diverted in Meade County, located on the plains north of the Black
Hills. An additional 14 cubic meters per second (500 cfs) are claimed
on tributaries to Bear Butte Creek, including 11 cubic meters per
74
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TABLE 10
SUMMARY OF WATER QUALITY DATA FOR DEAR BUTTE CREEK
(Data In mg/1 unless otherwise Indicated)
Bear Butte Creek ab.
Dissolved
Flow (ra /s)
(cfs)
EC (umlios per cm)
pll (standard units)
Calcium
Magnesium
Sodium
Potassium
Alkalinity
Sulfate
Chloride
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Zinc
Cyanide
Boulder Ck. Bear Butte Creek nr. Sturgls
Total Dissolved Total
0.0003-1 — 0.003-2.8
0.01-40 — 0.1-99
106-1690 -- 817-1600
7.1-8.8
110-244
29-70
20-55
6.4-8.3
38-272 — 392-876
319-760
0.7-13
0.04-0.12
0.17-0.21
V
Bear Butte Creek at Mouth
c/
Dissolved
7.0-7.5
285-294
105-107
138-147
5.40-7.07
0.002
0.010
0.004-0.010
0.002-0.050
0.002
0.050
0.015-0.025
0.0002
0.040-0.150
0.005-0.010
0.003-0.010
0.003-0.010
0.010
Total
0.008
3
2020-2120
291-306
105-111
126-139
6.08-6.40
1160-1180
38-41
0.002
0.010
0.004-0.010
0.050
0.271-0.650
0.050
0.030-0.041
0.0002
0.003-0.010
0.003-0.009
0.003-0.010
0.010
0.010
Sediment
8.2-8.3
80
b/
Samples analyzed from September 1969 and May 1973.
Samples analyzed from April 1960 to May 1962.
c/
Samples analyzed from February 1984 to April 1984.
Source: EPA STORET Data Base.
-------
second (400 cfs) from Spring Creek. Although Spring Creek is a tribu-
tary to Bear Butte Creek, it enters Bear Butte Creek near the conflu-
ence with the Belle Fourche River and originates at the foot of the
Black Hills rather than in them. No municipal use of Bear Butte Creek
was identified.
The site chosen for the hypothetical mining operation is located
in the Two Bit Creek drainage. This area is relatively flat, is boggy
in the spring during high runoff, and has a number of small beaver
dams. Its headwaters are at an elevation 1,700 meters (5,600 feet) and
the drainages traverses about 10 kilometers (6 miles) before joining
with Boulder Creek and emptying into Bear Butte Creek above Boulder
Canyon (see Figure 11). Water quality is generally good according to
recent sampling conducted in conjunction with the Gilt Edge Mine.
Water was slightly acidic. Free cyanide was generally below detection
although one sample was recorded at 0.021 mg/1. Lead, mercury and iron
were slightly elevated. No existing water rights were identified in
Two Bit Creek.
SOILS
General Soil Characteristics and Resource Uses
Soils in the Black Hills study area vary widely in physical
characteristics. Loamy, moderately deep soils occur mainly in the
central portions and the foothill sections of the Black Hills. Deeper
soils occur in drainage bottoms (U.S. Forest Service, 1983a). The
majority of the soils along the slopes in the three drainages are
derived from calcareous sandstones, limestones, and soft shales.
Drainageway soils were formed from alluvial sediments. Thirteen
general soil associations occur among the three drainages from their
headwaters to the confluence with the Belle Fourche River. Table 11
depicts the soil associations present in the Spearfish, Whitewood, and
Bear Butte Creek drainages. The principal upland associations in the
three drainages include the Citadel-Vanocker-Grizzly and Stovho-Trebor-
Rock Outcrop associations. The Barnum-Swint-St. Onge and Lohmiller-
Glenberg-Haverson associations are predominant in the drainage bottoms.
76
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TABLE 11
SOIL ASSOCIATIONS OCCURRING IN THE
SPEARFISH, WHITEWOOD, AND BEAR BUTTE CREEK
WATERSHEDS OF THE NORTHERN BLACK HILLS
WATERSHED.
SOIL ASSOCIATION LOCATION37
Citadel-Vanocker-Grizzly SC, WC, BB
Stovho-Trebor-Rock Outcrop SC
Paunsaugunt-Rock Outcrop SC, WC
Barnum-Swint-St. Onge SC, WC
Lohrailler-Glenberg-HaversoQ SC, WC
Pactola-Buska-Hisega WC, BB
Nunn-Satanta-Zigweid WC
Kyle-Pierre-Hisle WC
St. Onge-Keith WC, BB
Caputa-Satanta WC
Citadel-Vanocker BB
Tilford-Nevee BB
Canyon-Lakoa-Maitland BB
SC = Spearflsh Creek
WC = Whitewood Creek
BB = Bear Butte Creek
Source: Soil Conservation Service, 1976; 1978; 1979b.
77
-------
Soil types (series) in the Black Hills are similar among the three
drainages. On the plains, however, soil characteristics vary both
within and between drainages. Within each drainage, the soils types
depend on slope, aspect, and watershed position. Most soils in the
upper reaches of the drainages are moderately deep to deep. They are
well-drained and textures range from silts to loams. Soils along the
foothills become deeper and more well-drained. Textures of these
downstream alluvial soils range from silts and sands to clays. The
nearly level bottomland and terrace soils are subject to occasional
flooding. Many miles of the lower Whitewood Creek flood plain have
been affected by the release of mine tailings and numerous heavy metals
were identified in flood plain soils downstream of Lead and Deadwood
(Fox Consultants, Inc., 1984).
The soils in the Black Hills support land uses such as woodland,
wildlife habitat, rangeland, and recreation. Steep terrain in the
upper drainages near the three hypothetical mine sites has prevented
extensive residential development or production of crops.
Key Soil Physical and Chemical Characteristics
Selected chemical and physical characteristics of the most preva-
lent soils series in the three selected watersheds are provided in
Table 12. Most major soils in the drainage are silty or loamy in
texture. Clay content fluctuates with soil depth and type. The
majority of clays occur in deeper bottomland soils or deeper in the
soil profile. Upland soils are predominantly dry throughout the soil
solum. Surface soil moisture fluctuates with seasons of the year.
Permeability generally ranges from moderate to slow. Water retention
of upland soils, which is affected by soil texture and organic matter
content, is moderate. Organic matter content varies with location and
depth in the profile, with surface layers of the soils containing up to
10.5 percent organic matter. Deeper in the profile, organic matter
content averages less than 1 percent. The levels of calcium carbonate
vary considerably with depth. Carbonates occur at depths ranging from
25 to 100 centimeters (10 to 40 inches). Overall soil pH's range from
78
-------
TABLE 12
Soil Series
Citadel
Texture
fsl, vfsl, cl
c, si
Vanocker
Grizzly
Stovho
Trebor
Barn urn
Swlnt
St. Onge
Lohmlller
Glenberg
Haverson
Pactola
Buska
Hlsega
sll, alcl, cl,
ail, slcl
sll, slcl
sll, cl, 1
si, cl
sll, 1, vfsl
1, sll, si, cl
slcl
fsl, Is
1, sll, vfsl
sll, slcl
1, si, cl, slcl
1
fsl = fine sandy loam; vfsl
loamy sand.
SELECTED CHEMICAL AND PHYSICAL CHARACTERISTICS
FOR THE MOST PREVALENT SOIL SERIES IN THE
WHITEWOOD, SPEARFISH, AND BEAR BUTTE CREEK WATERSHEDS
Moisture
Content
To Bedrock Percent
Depth Clay
Percent
Organic
Matter
CaCO
b/
Nitrates
b/
Percent
Iron
(effer- (meq/1)
vescence)
Slight 0.1
Permeability
Slow-moderate
5.6-8.4
Dry throughout
Dry throughout
Dry to 48 Inches
Moist to 90 Inches
Moist throughout
Dry throughout
NAC/
NA
NA
Moist throughout
Moist throughout
Moist throughout
Dry throughout
Dry throughout
Moist throughout
very fine sandy loam; cl = clay loam; c =• clay; si = sandy loam; slcl = sllty clay loam; sll =• silt loam; 1 = loam; Is
150
150
150
115
150
150
150
150
150
150
150
150
180
21-36
7-44
21-45
19-46
NA
NA
NA
35-55
<18
18-35
21-29
9-12
9-14
<1-10.5
<1-6.0
-------
moderately acid (5.6) to very strongly alkaline (8.4). Most soils,
however, range from slightly acid to moderately alkaline. The presence
of iron is greater in soils near the towns of Lead and Deadwood along
Whitewood Greek, than in the Bear Butte and Spearfish drainages.
Higher iron levels in these areas may be due to historical mining
activities. Soils in upper Bear Butte Creek contain moderate levels of
iron.
VEGETATION
Regional Setting
A large portion of the Bear Butte Creek, Spearfish Creek, and
Whitewood Creek watersheds are part of the Black Hills National Forest.
Elevations within the Black Hills range from 900 meters (3,000 feet) to
2,000 meters (7,200 feet). Throughout this range in elevation there
are wide variations in climate, topography, and soils, all of which
affect vegetation.
Soils directly affect the kind and amount of vegetation that is
present. In the Black Hills, ridge and slope soils in areas of granite
and metamorphic parent material are relatively shallow, coarse text-
ured, and well drained (Orr, 1975). These soils generally support
ponderosa pine forest. The finer soil particles have been transported
and deposited on lower slopes and in valley bottoms. Hence, the soils
in these areas are generally finer textured, deeper, and more fertile.
Lower slope and valley soils support grassland and riparian vegetation.
Vegetation throughout the region has been disturbed by fires,
logging, mining, and other activities. Virtually all of the Black
Hills ponderosa pine forest has been converted to a well-stocked and
manageable second-growth forest (Boldt and Van Deusen, 1974). Approxi-
mately 60 percent of the Black Hills National Forest has tree stands
less than 100 years old. The forest is generally composed of small
diameter trees. About 75 percent of the trees are less than 9 inches
diameter at breast height (d.b.h.) (U.S. Forest Service, 1983a).
80
-------
Resource Use
The primary uses of the vegetation resources are livestock graz-
ing, timber production, wildlife habitat, and recreation. Although
specific data on these uses are not available for the study area,
considerable resource use information is available for the Black Hills
National Forest (U.S. Forest Service, 1983a) and adjacent Bureau of
Land Management (BLM) land (U.S. Bureau of Land Management, 1985). The
information is assumed to be representative of the general vegetation
resource uses throughout the study area.
Approximately 40 percent of the Black Hills National Forest is
considered suitable for livestock grazing (U.S. Forest Service, 1983a).
The remainder is unsuitable because of steep topography, dense over-
story vegetation, and lack of availability of water. During the 1980
grazing season, 29,600 cattle and 300 sheep, comprising 128,000
animal-unit months (AUM), were permitted to graze within the national
forest. The major portion of the grazing season occurs between June 1
and October 31.
On adjacent BLM land allotments, which occur primarily at lower
elevations than allotments in the Black Hills National Forest, the
grazing season extends from March through December. The BLM allotments
support about 74,000 AUM consisting of cattle and sheep (U.S. Bureau of
Land Management, 1985).
Ponderosa pine and white spruce are the commercially important
timber species. Ponderosa pine, aspen, birch, and bur oak are used for
firewood (U.S. Forest Service, 1983a). The current allowable sale
quantity is 34 million cubic feet (MMCF). Annual harvest levels have
averaged 102 million board feet of raw timber and roundwood product
material (U.S. Forest Service, 1983a). The demand for timber exceeds
the current allowable sale quantity in the national forest.
81
-------
Free firewood for personal use Is available. With the Increasing
use of wood stoves and fireplaces for home heating, it is expected that
the commercial firewood market will eventually develop and compete with
the sawtlmber and roundwood markets for available lumber (U.S. Forest
Service, 1983a).
Native vegetation of some flood plains and adjacent areas has been
converted to range and cropland. Crops grown include winter wheat,
oats, alfalfa hay, corn, and other cereal grains (Soil Conservation
Service, 1976; 1978; 1979b). Wildlife habitat and recreational uses
are described in the wildlife and socioeconomic sections of this
chapter, respectively.
Resource Characterization
Two major vegetation associations characterize the study area.
These are ponderosa pine forest and the grassland complex of the
northern Great Plains (Froiland, 1962; Severson and Thilenius, 1976).
Ponderosa pine forest is the predominant vegetation type in the Black
Hills, and covers more than 90 percent of the Black Hills area. At
lower elevations, where the forest and plains meet, the forest in some
places develops into an open ponderosa pine savannah (Froiland, 1962).
Elsewhere, there is an abrupt transition from forest to grassland.
Grasslands dominate the lower elevations and more level or less
mountainous portions of the study area. The primary plains grassland
type consists of wheatgrass and needlegrass. Grasslands are also
interspersed with forest vegetation in the Black Hills. Drier, shallow
soils support mixed prairie grasslands while moist, deep soils support
bluegrass grasslands.
At lower elevations, riparian vegetation typically consists of
cottonwood stands or stands of bur oak, American elm, green ash, and
eastern hop hornbeam (Froiland, 1962). At higher elevations, white
spruce, aspen, and paper birch form locally dense stands along streams
and on north-facing slopes (Pase, 1958). Willow, water birch, and
other shrubs become more abundant in riparian communities at the
highest elevations.
82
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Ponderosa pine, grasslands, aspen, and white spruce are the
dominant vegetation types in the Black Hills National Forest (Table
13).
TABLE 13
PERCENTAGE OF VEGETATION TYPES OCCURRING IN THE
BLACK HILLS NATIONAL FOREST
Vegetation Type Percent of Forest Total
Aspen 2.0
Grassland 6.6
Ponderosa pine 88.0
Wetlands 0.7
White spruce 1.0
Other 1.7
U.S. Forest Service, 1983a.
Aspen is a relatively minor vegetation type in the study area. In
the Black Hills National Forest this type comprises about 2 percent of
the total vegetation cover (U.S. Forest Service, 1983a). The dominant
species in the aspen forest are aspen, Woods rose, common snowberry,
spirea, and various forbs and grasses (U.S. Forest Service, 1986a).
Aspen stands primarily occur on relatively steep slopes with
northern or eastern exposures (Severson and Thilenius, 1976). The
elevational range for aspen in the Black Hills is 1200 to 2100 meters
(4000 to 7000 feet).
The Black Hills aspen stands described by Severson and Thilenius
(1976) ranged from dense stands of small, young trees to open, park-
like stands of large trees. The majority of stands had trees which
were only 20 to 40 years old. The trees were usually less than 10
centimeters (4 inches) d.b.h., although several stands had trees in the
10- to 20-centimeter (4- to 8-inch) d.b.h. size class. Few stands
contained larger trees. Many of the aspen stands had apparently
developed following wildfires in the 1930's.
83
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Because of the generally lush understories of aspen stands and
their frequent proximity to water, aspen stands are important to
livestock and to a wide variety of wildlife. Cattle, elk, and mule
deer use aspen stands for forage, escape and thermal cover, and for
calving (Hoover and Wills, 1984). In the Black Hills, aspen is also
used for firewood.
Grasslands
Grasslands in the study area can be subdivided into two major
categories for purposes of discussion: plains grasslands and mountain
grasslands. The salient characteristics of these grasslands are
described below.
Plains grasslands are typified by the wheatgrass grassland and the
wheatgrass/blue grama grassland (Johnson and Nichols, 1970; U.S. Bureau
of Land Management, 1985). These mid-grass grasslands are both dom-
inated by western wheatgrass. A variety of other grass and forb
species occur to form a series of complex prairie associations. These
grasslands occupy the gently rolling prairies throughout western South
Dakota and in the northern portions of the study area.
Plains grasslands are generally highly productive, although
production can vary with temperature, precipitation, and grazing
pressure. Most of the historical prairie in the region has been grazed
by domestic livestock for a long time (Soil Conservation Service,
1978). Significant acreages of plains grasslands have been converted
to cropland.
The two main types of mountain grasslands in the Black Hills are
the mixed prairie grassland and the bluegrass grassland (Severson and
Thilenius, 1976). The mixed prairie grassland consists of needle and
thread grass, blue grama, little bluestem, big bluestem, and western
wheatgrass and occurs on shallow, well-drained soils on south- and
west-facing slopes (Thilenius, 1971; Severson and Thilenius, 1976).
These primary grasses can occur in various combinations and relative
abundances, giving rise to several different community types.
84
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The bluegrass grassland, dominated almost exclusively by Kentucky
bluegrass, generally occurs along streams or, at higher elevations, on
deep, moist soils derived from sedimentary and metamorphic materials
(Severson and Thilenius, 1976). Mountain grasslands provide an import-
ant source of forage for livestock and wildlife species.
Ponderosa Pine
The general appearance of the Black Hills is a uniform forest of
ponderosa pine. However, there is a great deal of variation in the
forest understory. Six to ten ponderosa pine subtypes occur in the
study area (Thilenius, 1971; U.S. Forest Service, 1986a).
Ponderosa pine can be found on all slope aspects and throughout
the elevational range of the Black Hills. Stands vary from densely
stocked to open savannah in appearance. The more open stands have
higher forage production than the dense stands (Pase, 1958) and there-
fore are of greater forage value to livestock and wildlife. Inter-
mediate and densely stocked stands of ponderosa pine offer good wild-
life cover but little forage.
Ponderosa pine makes up 95 percent of the commercial timber volume
in the Black Hills (Pase, 1958). White spruce accounts for the remain-
ing 5 percent.
Wetlands
Wetlands occupy about 1 percent of the land in the national
forest. The following wetland communities may exist in the study area:
plains riparian woodlands, mountain riparian woodlands, riparian
shrublands, and sedge meadows. Other wetland types include various
water bodies in the area.
Plains riparian woodlands consist of stands containing various
combinations and relative abundances of plains cottonwood, eastern
cottonwood, narrow-leaf cottonwood, American elm, willow, box elder,
Russian olive, and bur oak (Severson and Thilenius, 1976; Fox Consult-
ants, Inc., 1984; U.S. Bureau of Land Management, 1985). Plains
riparian woodlands occupy narrow corridors along major streams and
85
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rivers in the lower elevations of the study area. These stands vary in
density and other basic vegetation characteristics in response to
changes in elevation, stream gradient, and local hydrology.
Progressing upstream into the Black Hills, the mountain riparian
woodlands exhibit changes in composition. The cottonwoods generally
are not as prevalent in the mountains as they are on the plains. The
dominant tree species are aspen and paper birch (Froiland, 1962;
Severson and Thilenius, 1976). American elm, green ash, box elder, and
hop hornbeam may also be locally common. Willows, red-osier dogwood,
and river birch form the understory in the mountain riparian woodlands.
Willows may assume local dominance in some areas and can form riparian
shrubland communities at higher elevations (Froiland, 1962; Thilenius,
1971).
Sedge meadows are limited in extent in the study area. They occur
in the Black Hills in low areas adjacent to streams and behind silted-
in beaver dams (Thilenius, 1971). Depending on hydrologic regime,
these meadows may be dominated by Nebraska sedge, other species of
sedges, tufted hairgrass, or reedgrass.
All of these riparian communities are very valuable to wildlife
and livestock and are used to a disproportionately greater extent than
other habitat types (Hirsh and Segelquist, 1978; Sands, 1978; Hoover
and Wills, 1984). The linear configuration of riparian systems, their
proximity to aquatic systems, and the physical and chemical inter-
actions between the riparian and aquatic systems provide a great number
and variety of habitats that are occupied by numerous organisms at all
trophic levels. The majority of rare plant species listed for the
Black Hills occur in riparian habitats.
White Spruce
White spruce stands, although they occupy only 1 percent of the
Black Hills National Forest, are commercially important for lumber.
About 5 percent of the commercially harvested timber in the Black Hills
is white spruce.
86
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White spruce occurs in moist habitats and reaches its best
development on north-facing slopes or along streams at higher eleva-
tions in the Black Hills (Thilenius, 1971; U.S. Forest Service, 1986a).
The understory is generally sparse.
Cropland
Crops are grown on the plains in the northern portion of the study
area. The majority of crops are grown in flood plains of the major
water courses and on upland plains of the area. The main crops are
winter wheat, oats, and alfalfa hay. Corn, sorghum, spring wheat,
barley, and rye are also grown (Soil Conservation Service, 1976; 1978;
1979b).
Other Vegetation and Land Use Types
Other minor types of vegetation and land use occur in the study
area. These include various shrubland types, disturbed land, water
bodies, and residential areas. None is extensive in areal coverage and
their use as vegetation resources for livestock and wildlife is
limited.
Special Concern Plant Species
The flora of the Black Hills contains a diverse assemblage of
plant species representative of the Rocky Mountain region, the northern
boreal forest, the eastern Great Plains, and the eastern deciduous
forest (Severson and Thilenius, 1976). As a consequence, many species
are at the edge of their distributional ranges and are considered rare
in the Black Hills even though they may be common elsewhere.
The South Dakota Department of Game, Fish, and Parks (1986)
prepared a list of special concern plant species for the Bear Butte
Creek, Spearfish Creek, and Whitewood Creek watersheds. No candidate
or federally-listed threatened or endangered plant species are known to
occur in these watersheds. Plants occurring along streams and flood-
plains in these watersheds, and which are considered rare or uncommon,
are listed in Table 14.
87
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TABLE 14
SPECIAL CONCERN PLANT SPECIES IN BEAR BUTTE CREEK,
SPEARFISH CREEK, AND WHITEWOOD CREEK WATERSHEDS
Plant Species and Drainage
Bear Butte Creek
Alder buckhorn
Spearfish Creek
Alaska oniongrass
Alpine rush
Beautiful fleabane
Dwarf scouring rush
Fairy slipper orchid
Green spleenwort
Hair sedge
Hood's sedge
Jointed rush
Kidney leaf violet
Low northern sedge
Maidenhair fern
Moonwort
Musk-root
Northern white-orchid
One-flower wintergreen
Rattlepod
Ground pine
Round-leaved orchid
Small white violet
Squashberry
Tufted hairgrass
Western mountain ash
Western saxifrage
White-vein wintergreen
Whitewood Creek
Broad-lipped twayblade
Delicate sedge
Green spleenwort
Hair sedge
Hood's sedge
Northern white orchid
Rattlepod
Small white violet
Small-flowered woodrush
Western mountain ash
Western saxifrage
White-vein wintergreen
Rhamnus alnifolla
Mellca subulata
Juncus alpinus
Erigeron formossisimus
Equisetum scirpoides
Calypso bulbosa
Asplenium viride
Carex capillaris
Carex hoodii
Juncus arcticulatus
Viola renlfolia
Carex concinna
Adiatum pedatum
Botrychium lunarla
Adoxa moschatelllna
Platanthera dilatata
Pyrola uniflora
Astragalus americanus
Lycopodlum obscurum
Platanthera orblculata
Viola macloskeyi
Viburnum edule
Deschampsia cespltosa
Sorbus scopulina
Saxifraga occidentalis
Pyrola picta
Listera convallarioides
Carex leptalea
Asplenium viride
Carex capillaris
Carex hoodii
Platanthera dilatata
Astragalus americanus
Viola macloskeyi
Luzula pariflora
Sorbus scopulina
Saxifraga occidentalis
Pyrola picta
Division
of Wildlife
Natural Heritage
Inventory Status
Undetermined
Rare
Rare
Undetermined
Rare (disjunct)
Rare
Rare (disjunct)
Rare (peripheral)
Undetermined
Rare
Undetermined
Rare (disjunct)
Historical record
Historical record
Rare (disjunct)
Rare
Undetermined
Rare (disjunct)
Undetermined
Historical record
Undetermined
Rare
Rare (peripheral)
Rare
Rare (disjunct)
Rare (disjunct)
Critically rare
Rare
Rare (disjunct)
Rare (peripheral)
Undetermined
Rare
Rare (disjunct)
Undetermined
Undetermined
Rare
Rare (disjunct)
Rare (disjunct)
Source: South Dakota Department of Game, Fish, and Parks, 1986.
88
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WILDLIFE
General Wildlife Resources
There are no wildlife refuges or other areas within the study area
managed specifically for wildlife by federal agencies. However, the
South Dakota Department of Game, Fish, and Parks has several properties
in each watershed that provide some relatively undeveloped land for
wildlife. Wildlife resources in the study area are readily accessible
to the public because of the abundance of public lands, both federal
and state.
Regional wildlife resources are diverse in type, with all major
wildlife groups represented (Table 15). The wildlife composition is
strongly influenced by the topographic conditions and vegetation types
present. Because most of the study area consists of upland vegetation
and habitat types, the overall wildlife character of the area is
upland. Semi-aquatic wildlife species such as waterfowl, shorebirds,
beaver, and muskrat are relatively uncommon, but may be abundant where
suitable habitat occurs.
The Black Hills and plains environments support different assemb-
lages of wildlife species. For example, principal wildlife species
associated with the ponderosa pine areas of the Black Hills include
elk, deer, porcupine, gray fox, red squirrel, sharp-shinned hawk,
Cooper's hawk, dipper, nuthatches, American robin, turkey, and ruffed
grouse (U.S. Forest Service, 1986a). Principal species associated with
the grassland vegetation types of the plains environment include deer,
coyote, red fox, black-tailed prairie dog, badger, pronghorn, golden
eagle, sharp-tailed grouse, turkey vulture, red-tailed hawk, western
meadowlark, and grasshopper sparrow (U.S. Forest Service, 1986a).
To simplify discussion of the large number of species, description
of the wildlife resource is accomplished by wildlife group (see Table
15). Species of special concern (primarily threatened or endangered
species) are discussed as a separate group. The comprehensiveness and
89
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TABLE 15
SUMMARY OF GENERAL WILDLIFE RESOURCES CHARACTERISTICS
Wildlife
Group
Large mammals
Small mammals
Furbearers
Waterblrds
Upland birds
Raptors
Songbirds
Amphibians and
Reptiles
Number Common
of Species Representatives
6 . Elk
. Deer
. Pronghorn
57 . Deer mouse
. Least chipmunk
. Fox squirrel
. Meadow vole
17 . Beaver
. Muskrat
. Coyote
57 . Mallard
. Green-winged teal
9 . Turkey
. Mourning dove
26 . Golden eagle
. American kestrel
. Red-tailed hawk
. Great horned owl
147 . American robin
. Red-winged blackbird
. Dark-eyed junco
. Western meadowlark
26 . Tiger salamander
. Leopard frog
Common Vegetatl<
Associations
. Ponderosa pine
. Aspen
. Grassland
. Ponderosa pine
. Aspen
. White spruce
. Grassland
. Ponderosa pine.
. Aspen
. Grassland
. Wetlands
. Ponderosa pine
. Aspen
. Grasslands
. Ponderosa pine
. Grasslands
. Ponderosa pine
. Grasslands
. Wetlands
. Ponderosa pine
. Wetlands
Comments
Most represenatlves of this group are
popular game species.
Species composition diverse and all
vegetation types occupied.
Except for muskrat and beaver, members of
this group tend to possess large home
ranges.
Most representatives of this group are
migrants.
Species mixture changes seasonally.
Members of this group tend to hunt
large territories.
. Species composition Is diverse, all
vegetation types are occupied, and
species mixture changes seasonally.
. All vegetation types are occupied.
Sources: American Ornithologists' Union, 1983; U.S. Forest Service, 1983b; MacCracken, 1984; Sharps and Benzon, 1984; U.S. Bureau of Land
Management, 1985; Vandel, 1986.
-------
specificity of available data for species and groups of species are
quite variable. Generally, information on game species is the most
extensively developed.
Large Mammals
Six species of large mammals potentially occur within the study
area: elk, mule deer, white-tailed deer, pronghorn antelope, black
bear, and mountain lion. Mule deer and white-tailed deer are the most
widely distributed species. Elk and antelope are more restricted; they
are found only in two portions of the study area and on the plains,
respectively. Black bear and mountain lion are classified as threat-
ened species by the State and are included in the discussion of species
of special concern.
White-tailed deer and mule deer are the most abundant and wide-
spread large mammals in the study area, and occur in all three water-
sheds. However, mule deer are most common in the Spearfish Canyon area
(Haeder, 1981). White-tailed deer appear to outnumber mule deer by
about three or four to one and are the most popular game species
(Haeder, 1981; U.S. Forest Service, 1983a). Approximately 50,000
white-tailed deer, and 10,500 mule deer inhabit the Black Hills Nation-
al Forest (U.S. Forest Service, 1983a). Approximately 10,000 mule deer
and white-tailed deer inhabitat the Black Hills portion of the study
area (B. Parrish, South Dakota Department of Game, Fish, and Parks,
personal communication, 1986). Their long-terra population trend has
been downward.
Deer winter range, summer range, and year-round range occur in the
study area (Figure 12). The hypothetical heap leach operations in the
Spearfish and Bear Creek drainages are both located in winter range.
The Whitewood Creek site is in summer range. Both winter and summer
ranges are considered critical habitat.
Swales, draws, lowlands, and river and creek flood plains make up
the most important white-tailed deer habitat (Petersen, 1984). The
deer use gently rolling upland areas the least. In western South
Dakota, white-tailed deer are primarily associated with coniferous
91
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FIGURE 12
ELK AND DEER HABITAT FEATURES
'••'•'.•'.•'•• •'.•'.•'•'.•'.•'•• •'.-'••'••.•'.•'•• '•'$' -v'-'•'/'••'• vv'-'-v^-HrT-V^^M^
.'•*.'• ••'•'.•'.• ^v^vv^vv vX vV^vv^vv>v>' '•'. •• .'• '. "••.-^
LEGEND
V//A DEER YE*R - ROUND RANGE
DEER SUMMER RANGE
DEER WINTER RANGE
ELK YEAR - ROUND RANGE
NORTH
-------
forest and riparian areas (U.S. Bureau of Land Management, 1985). The
ponderosa pine vegetation type is used extensively.
Mule deer can be found in most, if not all, of the vegetation
types occurring in the study area. However, they tend to prefer
grassland/shrubland, coniferous forest, and riparian areas (Severson,
1981; U.S. Bureau of Land Management, 1985). Mule deer will use the
somewhat drier, shrubby areas (such as juniper draws found in rough
breaks in the terrain) more heavily than will white-tailed deer
(Petersen, 1984). During the fall and winter, mule deer prefer more
open habitats over the heavily wooded slopes frequented during the
summer (Severson, 1981).
Elk and pronghorn antelope are relatively limited in their occur-
rence within the study area. Pronghorn occupy the plains environment
in the northern part of the study area. Approximately 400 elk inhabit
the Black Hills portion of the study area. Thirty to 50 elk inhabit
the eastern area of range and about 350 head occur in the western area.
Two areas have been identified as elk year-round range (Figure 12).
The hypothetical heap leach operations on Whitewood and Bear Butte
Creeks are located on the west and north edges, respectively, of the
eastern area of elk range. The Spearfish Creek site does not occur in
mapped elk range (Figure 12).
Furbearers
Approximately 17 species of furbearers potentially occur in the
study area (Sharps and Benzon, 1984; U.S. Forest Service, no date; U.S.
Forest Service, 1983b). Species known to occur in the area include the
coyote, raccoon, red fox, gray fox, long-tailed weasel, stripped-skunk,
beaver, and muskrat. Generally, furbearers are secretive and easily
overlooked.
Furbearer species composition and number of individuals vary by
vegetation type. Species most likely to occur in the widespread
ponderosa pine forest include the coyote, red fox, long-tailed weasel,
93
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and striped skunk. Beaver, rauskrat, and mink are essentially restric-
ted to wetland and riparian vegetation types. Common species of the
more open grassland vegetation type include the coyote, badger, and
long-tailed weasel.
Small Mammals
Approximately 57 species of small mammals potentially occur in the
study area (U.S. Forest Service, 1983b; Sharps and Benzon, 1984).
Small mammal species composition and number of individuals within any
geographical area vary with vegetation type and season. Common species
of the Black Hills environment include the deer mouse, red squirrel,
least chipmunk, Nuttal's cottontail, and porcupine. The black-tailed
jackrabbit, thirteen-lined ground squirrel, deer mouse, and meadow vole
are typical species of the plains environment.
Waterbirds
Approximately 57 species of waterbirds potentially occur in the
study area (American Ornithologists' Union, 1983; U.S. Forest Service,
1983b; Sharps and Benzon, 1984). Included are 21 species of waterfowl
and 26 species of shorebirds. Species composition and number of
individuals within any given geographical area vary with vegetation
type and characteristics of the local water bodies.
Waterfowl habitat occurring within the study area is of relatively
low quality. Desirable areas such as extensive ponds, marshes, and
larger oxbow pools are not present. Some waterfowl production probably
occurs in the general area but it is relatively minor in comparison
with the remainder of South Dakota (Brewster et al., 1976).
Waterfowl species composition varies with the season. Few species
and lower numbers of individuals are expected to occur during the
summer because the area provides very limited breeding habitat and that
which is present is attractive to only a small number of species. Use
by waterbirds peaks during the spring and fall migration periods.
94
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Upland Birds
Nine species of upland birds potentially occur within the study
area (U.S. Forest Service, 1983b; Sharps and Benzon, 1984). Species
composition and number of individuals within any given geographical
area vary with vegetation type and season. Upland birds occurring in
the Black Hills environment include the turkey, ruffed grouse, sharp-
tailed grouse, and mourning dove. The sharp-tailed grouse, ring-necked
pheasant, and mourning dove occur in the plains environment.
The wild turkey is probably the most widespread upland bird
species in the study area (U.S. Bureau of Land Management, 1985;
Parrish, 1986; U.S. Forest Service, no date). It is also the second
most popular game species in the Black Hills after white-tailed deer
(Haeder, 1981). Approximately 5,000 turkeys inhabit the Black Hills
portion of the study area (B. Parrish, South Dakota Department of Game,
Fish, and Parks, personal communication, 1986). Although, the turkey
population presently appears to be stable the objective is to increase
the population to about 10,000 birds (U.S. Forest Service, 1983a).
Raptors
Approximately 26 species of raptors potentially occur within the
study area (American Ornithologists' Union, 1983; U.S. Forest Service,
1983b; Sharps and Benzon, 1984). Included are 16 species of diurnal
birds of prey and 9 species of owls. Common species include the
sharp-shinned hawk, northern harrier, red-tailed hawk, golden eagle,
American kestrel, and great horned owl. Raptor species composition and
number of individuals within any given geographical area vary with
vegetation type and season.
Although the majority of raptor species potentially occurring in
the study area are generally tolerant of a wide variety of vegetation
types, preferences for certain features are common. Old-growth forests
are important to many of the owls because they are the major source of
95
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snags which the cavity-nesting species require (Rapheal and White,
1984). Cliffs occurring in the study area are potentially important as
nest sites, particularly for golden eagles, red-tailed hawks, and
prairie falcons.
Nests of breeding raptors undoubtedly occur in all three water-
sheds. Most probably have not been documented because many species are
inconspicuous and difficult to observe during the nesting season.
Nesting sites include snags, cliffs, tree tops, and the ground. The
more prominent breeding species include the golden eagle, red-tailed
hawk, and turkey vulture.
Songbirds
Approximately 147 species of songbirds potentially occur within
the study area (American Ornithologists' Union, 1983; U.S. Forest
Service, 1983b; Sharps and Benzon, 1984). Species composition and
number of individuals within any given geographical area vary with
vegetation type and season. Most of the vegetation types have rela-
tively large numbers of potentially occurring species.
Snags, which provide numerous nest-cavities, are found mainly in
old-growth forests and are particularly important to many species of
songbirds (Raphael and White, 1984). Riparian and wetland habitats are
also considered important in the study area because of their limited
availability and attractiveness to a relatively large number of song-
bird species.
Songbird species composition varies with the season. Approximate-
ly 38 species (26 percent of the total songbird species in the study
area) are considered to be year-round residents and 89 (60 percent) are
present only during the summer (American Ornithologists' Union, 1983).
The remaining 20 species (14 percent) are present only during the
spring and fall migration periods or the winter months.
96
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Amphibians and Reptiles
Approximately 26 species of amphibians and reptiles potentially
occur within the study area (U.S. Forest Service, 1983b; Sharps and
Benzon, 1984). Included are 7 species of amphibians and 19 species of
reptiles.
Species of amphibians and reptiles potentially inhabit all of the
vegetation types present. However, riparian and wetland vegetation
types are especially important to amphibians, which require surface
water to complete portions of their life cycles. Most reptiles prefer
drier shrublands and open coniferous forest. Amphibians may also be
found in these drier habitats during the nonbreeding season.
Species of Special Concern
Several wildlife species of special concern potentially occur in
the study area (Table 16). Species of special concern include federal-
and state-listed threatened or endangered species and species that are
proposed or are candidates for listing as threatened or endangered
species. Some state-listed species, such as the black bear, are of
concern due to limited numbers in South Dakota, even though they may be
common in other states.
Specific information about species occurrence in the three water-
sheds is relatively limited. The peregrine falcon, osprey, and bald
eagle are migrants. However, efforts are presently being made to
reintroduce peregrine falcon breeding pairs in the Black Hills (U.S.
Forest Service, 1983a). The presence of black-footed ferrets would be
limited to black-tailed prairie dog colonies that may occur in the
lower plains reaches of each watershed. Little is known about the
occurrence of the other species in the study area since documented
observations are lacking (Vandel, 1986).
Most of the special concern species primarily occur in upland
vegetation types such as ponderosa pine. The bald eagle and osprey are
also strongly associated with aquatic and riparian communities.
Peregrine falcons also tend to be associated with riparian vegetation.
97
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TABLE 16
SPECIAL CONCERN WILDLIFE SPECIES POTENTIALLY
OCCURRING IN THE STUDY AREA
Species
Ferruginous hawk
Swainson's hawk
Mountain plover
Peregrine falcon
Bald eagle
Long-billed curlew
Osprey
Mountain lion
Lynx
Black-footed ferret
Black bear
Swift fox
Official
Designation
CL
CL
CL
FE, SE
FE, SE
CL
ST
ST
CL
FE, SE
ST
CL, ST
a/
a/
FE: Federally Endangered
FT: Federally Threatened
CL: Candidate for Federal Listing
SE: State Endangered
ST: State Threatened
Comments
Restricted to grasslands
Common summer resident of
grasslands bit population
is declining
Last breeding records were
from Black Hills area in
1929
Rare migrant; breeding
pairs are being intro-
duced to the Black Hills
May nest in South Dakota
Uses short-grass plains
Rare migrant
Spotty distribution in
Black Hills
Extremely low numbers
Associated with prairie
dog colonies
Habitat decreasing
Habitat decreasing
Source: Houtcooper et al., 1985; U.S. Forest Service, 1983b; Sharps
and Benzon, 1984.
98
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AQUATIC LIFE
Aquatic life information for Bear Butte, and Spearfish Creeks is
limited. However, because of mining activities near Whitewood Creek,
information on that creek is available from several sources. Herricks
(1982) sampled Whitewood Creek from its headwaters to the confluence
with Belle Fourche River for water quality, stream morphometry, ripari-
an vegetation, aquatic macroinvertebrates, periphyton, and fish. He
also sampled Spearfish Creek for fish at one station, and for aquatic
macroinvertebrates at three stations. Fox Consultants, Inc. (1984)
sampled the downstream reaches of Whitewood and Spearfish Creeks for
fish and aquatic macroinvertebrates. The South Dakota Division of
Wildlife has sampled Spearfish and Bear Butte Creeks for fish in 1984
and 1985. Concurrently, macroinvertebrate sampling was conducted on
these creeks by South Dakota State University, but the information is
not yet available.
Whitewood Creek
Herricks (1982) defined four aquatic life zones of Whitewood Creek
(Figure 13). The cold water zone occurs from the headwaters to immedi-
ately upstream from Whitetail Creek. This zone is characterized by
cold water, depths less than 0.15 meter (0.5 feet), a steep gradient of
4 percent, and an aquatic community dominated by cold water species. A
transition zone, called intermediate limited cold water, exists from
the end of the cold-water zone to about Crook City. This stretch con-
tains well-developed pools and riffles, has a moderate gradient, and
includes both cold-water and warm-water species. A second intermediate
zone called intermediate - cool water, was defined from Crook City to
Township 7 North, Range 4 East, Section 25 of Lawrence County- This
stretch has a lower gradient than the upper intermediate zone. The
warm-water zone was characterized as having extended pool and deposi-
tional habitat, short riffles, shallow depths, a low gradient, and
warm-water flora and fauna. The South Dakota Board of Water Management
has classified the segment of Whitewood Creek upstream from Interstate
99
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O
o
FIGURE 13
AQUATIC LIFE ZONES IN
WHITEWOOD CREEK
1.
2.
3.
4
Km
LEGEND
COLD WATER
INTERMEDIATE - LIMITED
COLD WATER
INTERMEDIATE
COOL WATER
WARM WATER
(MODIFIED FROM HEHRICKS. 1982)
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90 to Gold Run Creek as "cold water marginal fishlife propagation"
which protects for stockings of catchable-size trout but does not
protect for fish reproduction.
Physical measurements were made throughout Whitewood Creek by
Herricks (1982). The location of morphometry sampling points are shown
on Figure 14. As would be expected, width and discharge increased from
upstream to downstream while gradient and percent of shaded area
decreased (Table 17). Mean depth increased slightly from 0.12 meter
(0.4 feet) to 0.18 meter (0.6 feet). Generally, particle size of
substrate decreased from upstream to downstream, but larger particles
(rubble and gravel) remain predominant below station W3 (Table 18).
Silt covers nearly 50 percent of the stream bottom at station W9 and
may be related to the influence of discharge from the Lead-Deadwood
Wastewater Treatment Plant. Streambank conditions are generally stable
although severe erosion was noted at station W6 and minor disturbances
occur throughout the stream length (Table 17). Trees and brush are
predominant in the riparian areas upstream from Lead, and grass and
bare soil cover the banks downstream from Lead.
Whitewood Creek receives discharges from the coal-fired Kirk Power
Plant immediately upstream from the town of Lead; from Gold Run,
a tributary which carries the effluent from the Homestake Mining
Company; and from the Lead-Deadwood and Whitewood wastewater treatment
plants. The Lead-Deadwood wastewater treatment plant is a secondary-
partial tertiary facility which was installed in 1979. The temperature
of the effluent is 15 to 20 °C (60 to 70 °F) and the ammonia concentra-
tions are typically 0.1 to 0.5 mg/1. The Whitewood facility provides
secondary treatment and is not as sophisticated as the Lead-Deadwood
facility (Lead-Deadwood Wastewater District, 1986). The Kirk Power
Plant is equipped with two cooling towers which cool the effluent to 15
to 20 °C (60 to 70 °F) (T. Stalcup, Kirk Power Plant, personal communi-
cation, 1986). The Homestake effluent is warmed by water from the
mine, but the temperature of Whitewood Creek downstream from the
confluence with Gold Run is regulated to remain below 24 °C (75 °F).
Bacterial degradation treatment of the effluent began in 1984 and has
101
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FIGURE 14
LOCATIONS OF PHISICAL MESUREMENTS
Km
(MODIFIED FROM HERRICKS. 1O82)
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TABLE 17
SUMMARY OF PHYSICAL MEASUREMENTS OF WHITEWOOD AND SPEARFISH CREEKS
Station
I
Whitewood
W2
W3
W4
W5
W6
W7
W8
W9
W10
Wll
Mean
Width
(meter
Creek
2.1
1.7
4.75
4.57
4.60
4.85
5.94
7.38
6.61
9.97
Mean
Mean
Mean
o
U)
Spearfish Creek
SP1 4.63
SP2 7.47
Depth Velocity Discharge
neters) (m/s)(m /s)
0.12
0.06
0.12
0.12
0.15
0.12
0.18
0.21
0.18
0.15
0.27
0.37
0.27
0.21
0.30
0.27
0.15
0.70
0.37
0.30
0.46
0.46
0.27
0.24
0.11
0.03
0.14
0.16
0.15
0.32
0.34
0.45
0.42
0.48
0.27
0.56
Riffle:
Pool
1:2
1:1
1:1
1:1
1:1
3:1
2:1
2:1
2:1
4:1
1:4
3:1
Stream
Gradient
(percent)"
4.5
2.5
3.0
2.0
2.9
2.3
1.8
1.1
1.9
0.8
2.0
2.3
Shaded
Stream Area
(percent)
45
45
20
30
30
10
10
20
35
10
50
60
Bank
Stress
road, RR
erosion, ash pile
road, erosion
road, construction
construction, erosion, road
road, channelized, RR
road, channelized
road, mine
grazing
grazing
road, summer homes
recreation
Source: Modified from Herricks, 1982.
-------
TABLE 18
SUMMARY OF SUBSTRATE MEASUREMENTS OF WHITEWOOD AND SPEARFISH CREEKS
Percent of the Bottom Covered by
Station
Whitewood
W2
W3
W4
W5
W6
W7
W8
W9
W10
Wll
Spearf ish
SP1
SP2
Boulder
Creek
40
55
9
3
14
6
20
0
14
0
Creek
2
10
Rubble
15
30
24
28
29
71
35
17
21
35
12
45
Gravel
0
10
20
21
19
10
25
38
51
47
17
20
Sand
0
5
27
14
7
5
10
3
5
5
21
15
Silt
25
0
10
22
24
7
5
42
8
10
3
0
Plants
20
0
10
12
0
0
0
0
0
2
43
5
Debris
0
0
0
0
7
1
5
0
1
1
2
5
Embeddedness
(percent)
45
30
35
20
25
20
45
60
35
60
60
70
Source: Modified from Herricks, 1982.
-------
rendered the effluent non-toxic (F.D. Fox, Homes,take Mining Company,
personal communication, 1986). Before 1984, the effluent contained
concentrations of cadmium, copper, cyanide, iron, lead, nickel, silver,
and zinc which adversely impacted Whitewood Greek.
Fish
The fish community is dominated by brook trout from the headwaters
to immediately upstream from Gold Run (station W7), the source of dis-
charge from Homestake Mining Company (Figure 15 and Table 19). Only
three other species were captured above Gold Run during Herricks'
(1982) study: long-nose dace, green sunfish, and brown trout.
Herricks proposed that this upper portion of Whitewood Creek was
isolated by the Gold Run wastewater discharge which created a block to
fish movement. Herricks felt this hypothesis was supported when creek
chub larvae were captured at station W9. where fish had not been caught
previously in the study, following water quality improvement. The
improvement occurred due to reduced discharge from the Horaestake Mining
Company and high spring flows in 1982.
The brown and brook trout populations are wild and in 1981 were
primarily composed of individuals less than 15.25 centimeters (6
inches) in lengh (Herricks, 1982). Factors which appeared to be
limiting growth were low streamflow, which created large, shallow areas
and high temperatures (Herricks, 1982). Trout were observed to be
stressed by high temperature during the July 1981 sampling. Further-
more, an analysis of fish scales revealed that false annul! were
commonly produced. False annuli can be related to stress and are
produced when growth ceases (Herricks, 1982).
During the course of the study by Herricks (1982), fish were not
caught downstream from station W5 except at station W14, the lowermost
station near the confluence with the Belle Fourche River (Table 19).
However, since the installation of the treatment process at the Home-
stake Mining Company in 1984, the water quality of Whitewood Creek has
105
-------
FIGURE 15
FISH SAMPLING SITES
Km
(MODIFIED FROM HEBRICKS. 1 882 >
-------
TABLE 19
SPECIES AND NUMBERS OF FISH CAUGHT PER 100 METERS IN RECENT STUDIES OF UHITEWOOD CREEK, SOUTH DAKOTA
SPECIES
March 1981
Broun trout
(Salmo trutta)
Brook trout
Salvelinus fontinalts
Long-nose dace
Rhinichthys cataractae
White sucker
Catoatomums commersonl
Mountain sucker
Catostomus platyrhynchua
July 1981
Brown trout
Salmo trutta
BrocT
trout
Salvellnus fontlnalls 19
Long-nose dace
Rhlnlchthys cataractae
September 1981
Brown trout
Salmo trutta
Broo
trout
Salvellnus fontlnalls
Long-nose dace
Rhlnlchthya cataractae
Carp
Cyprinus carplo
Creek chub
Semotllus atromaculatus
Lake chub
Couesles plumheua
Flathead chub
Hybopsls gracllls
Sand shiner
Notropls stramlneus
Plains minnow
llybognathus placitus
Fathead minnow
Plmephales promelaa
White sucker
Catostomus commersoni
Mountain sucker
Catostomus platyrhynchus
Black bullhead
Ictalurus melas
Wl W2
90 42
2
U3 U4
2 19
150 121
2
STATION
W5 W6 W7 W8 W9 W10 Wll W12 W13
a/
no no no no — —
fish fish fish fish
2 7
26 26
1 1 1
W14
~~°"
no
fish
no
fish
no
fish
no
fish
8
173
1
14
188
30
18 26
370 373
10 1
2
91
1
11
404
1
10
78
20
182
1
16
43
8
2
60
86
no
fish
no
fish
no
fish
no
fish
(continued)
2
1
1
4
4
1165
6
350
1
7
1
-------
TABLE 19 (Continued)
O
00
SPECIES
VI
W2
W3
W4
W5
W6
W7
STATION
W8 U9
W10
Wll
W12
W13
W14
Stone cat
Noturus
flavus
Plains klllltlsh
Fundulus zebrlnus
White bass
Morons cli ry sop a
Black crapple
Pornoxl3 nigromaculatus
Green aunflsti
Lepomls cyanellus
March 1982
Broun trout
Salmo trutta
Brook trout
Salvellnus fontlnalls
Long-nose dace
Rhinlchthys cataractae
July 1983
Creek shub
Semotllus atromaculatus
Ca~rp
Cyprlnus carplo
Flathead chub
Hybopsls gracllls
White sucker
Catostomus commersonl
6
7
1
1
42
231
32
130
104
17
5
a/
Stone cat
Notorus flavua
Indicates the station was not sampled
4 3
4 25
3
8 7
Source: derricks, 1982.
-------
improved sufficiently to support a trout population. The stream seg-
ment downstream from Lead is stocked with catchable (20- to 25-centi-
meter or 8- to 10-inch-long) brown trout. However, it is fished only
lightly because the public has not yet recognized that this segment is
now capable of supporting fish life (R. Ford, South Dakota Department
of Game, Fish and Parks, personal communication, 1986). The collection
of fish species (shiners, chubs, sunfish, and bullheads) at station W14
is typical of a warm-water fish community of prairie streams. Warm
water, primarily nongame, fish species were also captured in the lower
reach of Whitewood Greek in 1983 by Fox Consultants, Inc. (1984) (Table
19).
Macroinvertebrates
Herricks (1982) identified a total of 262 macroinvertebrate taxa
from Whitewood and Spearfish Creeks. Sampling was concentrated on
Whitewood Creek with Spearfish Creek serving as a reference area.
Sample locations are shown on Figure 16. Of the collected taxa, 93
were dipterans (flies) and 45 were coleopterans (beetles). The most
abundant functional group was the collector-gatherers which gather
particulate food materials (Table 20). Collector-filterers were a
distant second in importance. These organisms also use particulate
material, but they collect it with nets or body structures to filter
the water. Shredders were found only in the upstream stations, which
is a common pattern in streams. Shredders use coarse particulate
material which enters the stream from the terrestrial environment and
is an important food source to low-order, or headwater streams.
The macroinvertebrate assemblage was most diverse upstream from
Gold Run (station W8). Particularly notable in the upstream area was
the abundance of plecopteran (stonefly) species which were not observed
downstream from Gold Run. Plecopterans are typically intolerant of
pollution and prefer cold, fast, well-oxygenated water (Merritt and
Cummins, 1984). The functional diversity of upper Whitewood Creek was
consistently higher than that of other reaches and indicated a commun-
ity of complex trophic relationships.
109
-------
FIGURE 16
AQUATIC MACROINVERTEBRATE
SAMPLING SITES
Km
(MODIFIED FROM HERRICKS .1 982 >
-------
TABLE 20
Station Scraper
a/
AVERAGE PERCENT OCCURRENCE OF AQUATIC MACROINVERTEBRATE FUNCTIONAL GROUPS
IN WHITEWOOD AND SPEARFISH CREEKS, SOUTH DAKOTA
FUNCTIONAL GROUP
Collector- Collector- Piercer- General
Fllterer
Shredder
Predator
Gatherer
Fllterer
Parasite
Predator
a/
Unknown
Whlteuood
W2
W3
W4
W5
W6
W7
W8
W9
W10
W14
W15
U16
Spearf Ish
SP1
SP2
SP4
Creek
4.3
4.1
5.9
6.9
8.2
7.0
0
0
2.2
1.7
0.2
2.1
Creek
0
3.1
9.1
3.2
0
1.5
0
1.6
1.4
0
0
0
0
0
0
4.1
3.1
1.8
9.7
12.2
7.4
8.3
4.9
9.9
0
0
0
0
0
0
10.8
9.4
1.8
11.8
13.3
8.8
11.1
11.5
11.3
12.5
0
15.2
6.4
2.0
6.4
0.1
15.6
10.9
40.9
35.7
44.1
30.6
36.1
32.4
56.3
73.9
37.0
46.8
18.3
46.8
40.5
40.6
38.2
14.0
13.3
11.8
16.7
16.4
16.9
6.3
8.7
19.6
25.5
78.5
25.5
10.8
9.4
12.7
3.2
3.1
4.4
4.2
4.9
4.2
0
0
4.3
4.3
0
4.3
4.1
3.1
3.6
9.7
15.3
10.3
16.7
9.8
11.3
6.3
8.7
8.7
8.5
0
8.5
16.2
9.4
16.4
3.2
3.1
5.9
5.6
6.6
5.6
18.8
8.7
13.0
6.4
0
6.4
5.4
6.3
5.5
Herrlcks defined general predators as those organisms which are predaceous but supplemented their diet with plant and detrltal
material.
Sources: Herrlcks (1982) except Station W15 which Is from Fox Consultants, Inc.(1984).
-------
The Kirk Power Plant discharge from cooling tower blowdown appear-
ed to exert periodic, temporary impacts on the macroinvertebrate
community downstream from the discharge (Herrlcks, 1982). Station W5,
below this discharge, was the only station upstream from Gold Run where
plecopterans were not collected during one sampling visit (Herricks,
1982).
The Deadwood wastewater treatment effluent also affects the water
quality at one station downstream (Herricks, 1982). This was indicated
by the abundance of oligochaetes (worms) which are stimulated by large
amounts of fine particulate organic matter.
Herricks (1982) concluded that the discharge from the Homestake
Mining Company was clearly responsible for major changes in the macro-
invertebrate community from station W8 to W15. From Gold Run to Crook
City (W10), the number of taxa was considerably reduced (Table 21).
Taxa collected at these stations were pollution-tolerant species such
as Optioservus divergens (beetle), Coptotomus longulus (beetle),
Deronectes striatellus (beetle), Tubifix tubifix (Oligochaete), Eiseni-
ella tetraedra (oligochaete), Dixa sp. (fly), and Physa sp. (snail)
Other widespread and tolerant species such as Baetis tricaudata (may-
fly), Hesperophylax sp. (caddisfly) and Cheumatopsyche sp. (caddisfly)
were found at most stations but not at the two immediately downstream
from Gold Run. The three stations downstream from Gold Run (W8, W9,
W10) had significantly fewer numbers of taxa but not numbers of indi-
viduals. Analyses indicated that the number of organisms and taxa were
similar at the three stations downstream from Gold Run (W8, W9, W10).
Often the number of organisms and taxa at these stations were statis-
tically similar to Stations W10, W15, W16, W17, and W18 as well indi-
cating that the effects of pollution extended downstream to the mouth
of the creek. Stations W8 and W9 also exhibited groups of macroinver-
tebrates which were functionally similar. The diversity of functional
groups was low at these two stations, indicating a lack of complex
trophic linkages within the macroinvertebrate community (Table 22).
112
-------
TABLE 21
Mean
NUMBER OF AQUATIC MACROINVERTEBRATE TAXA COLLECTED FROM VJHITEWOOD AND SPEARFISH CREEKS, SOUTH DAKOTA
IN MARCH THROUGH DECEMBER, 1981 AND MARCH, 1982
Uhltewood Creek _ Spearfiah Creek
Date
March
May
July
October
December
March
Wl W2
39
33 39
36
24 26
23 40
28
W3
26
17
21
19
38
33
U4
29
24
12
18
29
27
W5
28
35
21
20
34
23
W6
23
19
22
17
27
24
W7
20
30
18
23
30
34
W8
4
4
18
4
3
3
«9
9
9
16
7
5
5
W10
9
10
22
11
8
8
W14
17
19
25
19
21
27
W15
—
20
22
—
24
19
W16
—
—
25
11
18
16
W18 SP1
29
30
20 17
19
32
19 26
SP3
42
—
26
—
35
31
SP4
—
48
46
21
55
42
27
35
26
23
27
20
26
11
21
16
18
19
25
33
42
Source: Herrlcka, 1982
-------
TABLE 22
a/
DIVERSITY OF AQUATIC MACROINVERTEBRATE FUNCTIONAL GROUPS
IN WHITEWOOD AND SPEARFISH CREEKS, SOUTH DAKOTA
Station March July October March
Whitewood Creek
W2
W3
W4
W5
W6
W7
W8
W9
W10
W14
W16
1.65
1.77
1.45
1.10
0.99
0.73
0.05
0.75
0.39
1.75
—
1.50
1.57
1.45
0.69
1.02
1.17
0.13
0.63
1.35
1.24
1.17
1.58
1.95
1.41
0.79
0.92
1.05
0.06
0.13
1.71
0.95
1.28
1.79
2.06
1.11
1.09
1.24
1.15
0.07
0.10
1.63
1.88
1.94
Spearfish Creek
SP1 1.90 1.67 1.68 1.72
SP2 1.73
SP3 -- — — 1.67
SP4 1.90 1.67 1.68 1.72
a/
Shannon-Wiener Diversity Index.
Source: Herricks, 1982
114
-------
The benthic community showed signs of recovery from pollution
impacts starting near Crook City, but the creek also changes to a warm
water habitat in this stretch. The lower stations W14, W15, W16, and
W18, had a diverse assemblage of warm water macroinvertebrates.
Odonata (dragonflies), trichoptera (caddisflies), diptera (flies) and
coleoptera (beetles) became prevalent but their numerical contribution
to the assemblage differed among these stations. In this segment,
numbers of taxa were greatest at station W14 (see Table 21), possibly
due to a more varied substrate (Herricks, 1982). The functional
diversity of lower Whitewood Creek approached or equaled that of the
community upstream from Gold Run (see Table 22), but the trophic
structure was different. No filterers or shredders were downstream
from Gold Run because less coarse particulate material was present in
the stream. The proportion of collector-filterers was greatest at the
downstream stations, indicating a greater amount of fine particulate
material in the stream (Table 20). These observations are expected
with a downstream progression. Herricks (1982) concluded that the warm
water zone of Whitewood Creek was substantially improved but not
completely recovered from upstream municipal and industrial wastewater
impacts.
Metals Accumulation in Macroinvertebrates
Composite macroinvertebrate samples from contaminated stream
reaches had higher mean concentrations of some metals than the com-
posite macroinverebrate sample from uncontaminated reference streams
(Belle Fourche River above Whitewood Creek, Spearfish Creek, and False
Bottom Creek) according to sampling and analyses performed by Fox
Consultants, Inc. (1984). In the contaminated areas of Whitewood Creek
and the Belle Fourche River (below Whitewood Creek) macroinvertebrate
samples had higher mean concentrations of arsenic, cadmium, copper,
iron, manganese, mercury, nickel, and silver (Table 23). However, only
arsenic, selenium, and silver values were statistically higher. The
most notable differences were apparent for arsenic (where contaminted
areas had a mean concentration approximately 60 times greater than the
reference station mean), cadmium (about 4 times greater), and copper
115
-------
TABLE 23
COMPARISON OF MEAN METAL CONCENTRATIONS IN THE
COMPOSITE MACROINVERTEBRATE SAMPLES FROM CONTAMINATED
AND REFERENCE STATIONS
Mean Concentration (mg/kg) ,
M« ^ o 1 /"> —.— *• -i— -I — « 4- *Tj O -fc *» *• J .«.«.-. *""^Tl « £r>*\*« ** A A O ^ *% ^ 4 >K « *« '
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Zinc
a/
Contaminated stations are Whitewood Creek Stations W10, Wll, W12,
W13, W14, W15, W17, W18, and the Belle Fourche River below
Whitewood Creek on the Belle Fourche River; Spearfish Creek
Station SP3, and a site on False Bottom Creek, a tributary to the
Redwater River.
b/
Based on one value.
c/
Not detected.
Source: Fox Consultants, Inc. (1984).
Contaminated Stations"'
61 + 38
0.8 + 0.7
1.0 + 1.4
22 + 13
1166 + 508
1.5 + 0.7
133 + 55
<0.09 + 0.05
3.4 +_ 4.7
<0.5b/
0.3 +_ 0.1
29 + 8
Reference Stations"
1 + 0.1
0.2 + 0.1
0.9 + 0.7
8.0 + 2.4
669 + 526
1.4 + 0.8
102 + 70
<0.02C/
1.6 + 1.2
0.9 +_ 0.2
NDC/
31 + 12
116
-------
(about 2.8 times greater). Silver was reported from seven of nine
invertebrate samples from the contaminated stations, but was not
reported from any reference station samples. Mercury was reported from
six of nine invertebrate samples from the contaminated stations and
from only one of the three reference station samples. The mean sele-
nium concentration was higher in reference stream macroinvertebrates
(0.9 mg/kg) than in the contaminated stream macroinvertebrates (0.5
mg/kg). There were no apparent differences in chromium, zinc, and lead
concentrations between reference stream and contaminated stream sec-
tions. Composite macroinvertebrate samples taken from stations with
high metal concentrations in the sediments generally tended to have
higher concentrations of the same metals. The trend, however, was not
consistent for all metals and all stations. The most notable examples
of the trend were arsenic, copper, iron, and manganese. The highest
macroinvertebrate arsenic levels occurred at W13, W14, W15, and W17.
Spearfish Creek
Spearfish Creek is a relatively unimpacted stream that has been
used as a reference stream in studies by Herricks (1982) and Fox
Consultants, Inc. (1984). Two major stream diversions occur upstream
from the town of Spearfish for hydropower generation. One diverts
water about 1.5 kilometers (1 mile) upstream from the confluence with
Llitte Spearfish Creek and releases it back to the stream about 8
kilometers (5 miles) downstream. The other diverts water from just
downstream from Squaw Creek and releases it back to the stream near the
town of Spearfish. This river segment is normally dewatered even
without diversions as the stream flows into the Pahasapa Limestone.
The gradient of Spearfish Creek is about 2 percent in the interme-
diate reaches, which is similar to the gradient of the intermediate
reaches of Whitewood Creek (see Table 17). Based on the data from
those reaches where the substrate was sampled, Spearfish Creek appears
to have fewer boulders and a more even distribution of rubble, gravel,
and sand over its bottom than Whitewood Creek (see Table 18). The
117
-------
large amount of embeddedness Is due to a travertine coating from spring
water high in dissolved solids (Herricks, 1982). Its banks are stable
and covered with trees at stations SP1 and SP2 (see Figure 14).
Fish
The fish community is dominated by brown trout (Table 24). Brook
trout, white suckers and long nose dace are other members of the
community. Upper Spearfish Creek (SP3, SP4, SP5, SP6, SP10, SP11),
East Spearfish Creek (Hannah Creek) (SP1 and SP2), and Little Spearfish
Creek (SP7, SP8, SP9) were populated by brown trout less than 8 inches
in length (Table 25). A catch-and-release fishing regulation exists on
East Spearfish Creek. At station SP10 nearly half the captured fish
were longer than 8 inches.
Catchable brown trout are stocked primarily in the town of Spear-
fish (stations SP15 and SP16), which accounts for the larger fish at
these stations. These fish would only be able to migrate upstream
during spring runoff because at other times the stream segment from
Rubicon Gulch to Spearfish is dry. Limited stocking is performed
upstream from Rubicon Gulch, and is probably responsible for the larger
number of 23-centimeter (9-inch) trout at stations SP10, SP12 and SP13.
Except for this limited stocking and possible migrants from the Sturgis
area during high water, the trout population upstream from SP14 is
sustained by natural reproduction.
Stream improvement consisting of wing deflectors, has been per-
formed by South Dakota Division of Wildlife. These, in conjunction
with catch and release regulations at stations SP12 and SP13, which
probably enhance the maintenance of larger fish in this stream stretch.
Station SP14 is actually in a segment of the creek which has nearly
been dewatered. Apparently some pools remain to permit survival of
small fish.
Macroinvertebrates
The high numbers and diversity of macroinvertebrates from upper
and lower Spearfish Creek indicate that there is no impairment of water
quality or habitat (see Figure 16 and Tables 20 and 22). The assem-
118
-------
TABLE 24
SPECIES AND NUMBERS OF FISH CAUGHT PER 100 METERS IN RECENT STUDIES OF SPEARFISII CREEK, SOUTH DAKOTA
SPECIES
SP1
March 1981
Brown trout
Salmo trutta
Brook trout
Salvellnus fontlnalls
July 19818/
Brown trout
Salmo trutta
Brook trout
Salvellnus fontlnalls
September 1981a/
Brown trout
Salmo trutta
White sucker
Catostomus commersonl
March 1982
Brown trout
Salmo trutta
Brook trout
Salvellnus fontlnalls
Long-nose dace
Rhlnlchthys cataractae
White sucker
Catostomus commersonl
July 1985b/
Brown trout
Salmo trutta 118
Brook trout
Salvellnus fontlnalls 1
Rainbow trout
Salmo galrdnerl
STATION
SP2 SP3 SP4 SP5 SP6 SP7 SP8 SP9 SP10 SP11 SP12 SP13 SP14 SP15 SP16 SP17
275
4
372
20
32
25
451 45
15 1
71
8
252 348 414 400 369 14 2 452 329 284 206 302
83 53 2 1 27 7 25
1 66 84
August 1985
Brown trout
Salmo trutta 414
October
Brown trout
Salmo trutta 209 191
Rainbow trout
Salmo galrdnerl 2
Source: Herrlcks, 1982.
Source: South Dakota Game, Fish, and Parks Department, 1986.
-------
Station
SP1
SP2
SP3
SPA
SP5
SP6
SP7
SP8
SP9
SP10
NJ
O
SP11
SP12
a/
SP13
SP14
SP15
b/
SP16
c/
TABLE 25
PERCENTAGE OF THE TROUT POPULATION IN SPEARFISH CREEK
GREATER AND LESS THAN 20 CENTIMETERS (8 INCHES) IN LENGTH
Species
Brown trout
Brown trout
Brown trout
Brown trout
Brown trout
Brown trout
Brown trout
Brook trout
Brown trout
Brown trout
Brown trout
Brown trout
Brook trout
Rainbow trout
Brown trout
Brook trout
Rainbow trout
Brown trout
Rainbow trout
Brown trout
Brown trout
Brown trout
Brown trout
Brown trout
Brown trout
Brown trout
Percent Less
Than 20 cm
Mean Length
of < 20 cm Group
Percent Greater
Than 20 cm
83
86
90
98
74
71
79
97
92
51
73
48
100
80
21
100
53
46
80
94
62
58
65
66
51
66
5
5
5
5
6
5
7
6
6
6
6
6
5
5
6
6
6
6
4
6
4
6
6
6
6
6
b/
a/
Two electrofishing efforts were conducted at this station.
Four electrofishing efforts were conducted at this station.
c/
Two electrofishing efforts were conducted at this station.
Source: South Dakota Department of Game, Glsh, and Parks, 1986.
Mean Length
of > 20 cm Group
17
14
10
2
26
29
21
3
8
49
27
52
20
69
9
9
9
8
9
9
9
8
9
9
9
9
9
9
47
54
20
6
38
42
35
34
49
44
9
9
9
9
11
10
10
10
10
9
-------
blage of organisms collected at station SP1 was similar to those
collected at stations Wl, W2, and W4 in the Whitewood Creek drainage.
Collector-gatherers dominated the benthic community at all the sampling
sites (Table 20). Collector-fIlterers and predators collectively made
up 20 to 30 percent of the community at the sampling sites. Filterers
were somewhat more important in Spearfish Creek than in Whitewood
Creek. Shredders maintained representatives in the benthic community
at upper and lower sites in Spearfish Creek but were not found in
Whitewood Creek below W8. This indicates that Spearfish Creek receives
terrestrial material such as leaves from the riparian area throughout
its length. Herricks (1982) did not discuss the taxa of Spearfish
Creek, but Fox Consultants, Inc. (1984) described the proportion of
macroinvertebrate families found In the benthic community at SP3.
Hydropsychidae (caddisfly), Baetidae (mayfly), and Perlodidae (stone-
fly) comprised 37, 30, and 11 percent, respectively, of the collection.
Elraidae (beetles) and Chironomidae (midges) made up 8 percent of the
collection. This assemblage, particularly with the good representation
of stoneflies and high functional diversity (Table 22), indicates a
healthy stream free of major disturbances even in its lower reach.
Bear Butte Creek
Bear Butte Creek from its headwaters to Boulder Canyon is a small,
high-gradient stream with substantial canopy cover. Its substrate is
dominated by rubble and gravel and the riparian vegetation consists of
pine and spruce forest with an understory of shrubs and thick grass.
In the upper reaches, several beaver dams create pools. The site
inspection suggested some impact by mine drainage from Strawberry Creek
and drainage from a mine near Galena may exist, but water quality
analyses (EPA STORET data base) did not reveal any contamination of
concern. Precipitated organic material was also observed upstream from
Strawberry Creek during the site Inspection. This may originate from a
small resort which offers trout fishing in a stocked pond and will fry
customers' catches.
121
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Fish sampling of Bear Butte Greek at four locations by South
Dakota Division of Wildlife (Figure 15) produced four species of
nongarae fish in low densities (Table 26). However, wild brown and
brook trout populations are known to exist in the creek (R. Ford, South
Dakota Department of Game, Fish and Parks, personal communication,
1986). Bear Butte Creek upstream from Boulder Canyon where it sinks
into the Pahasapa Limestone is isolated from fish populations down-
stream from Boulder Canyon, which could otherwise populate the upper
portions of the creek. Bear Butte Creek was stocked in April and June
1986 east of Sturgis with 700 catchable (20- to 25- centimeter or 8- to
10-inch-long) brown trout.
SOCIOECONOMICS
The description of the affected environment for socioeconomics
begins with a brief comparative analysis of key socioeconomic factors.
The geographic focus of this comparative analysis is a three-county
region containing Lawrence, Meade, and Pennington Counties, which are
linked by a number of economic, historical, and governmental/institu-
tional ties. Comparative data for South Dakota is also presented to
provide another comparative perspective.
Following the regional overview, the focus of the discussion
narrows to Lawrence County and the communities and surrounding environs
of Lead and Deadwood. This geographic area encompasses the locations
of existing and future gold deposit exploration and raining activity, as
well as the primary area of influence for potential socioeconomic
impacts. The descriptions are based on secondary data sources, person-
al observations in the area and discussions with local government
officials and residents.
Finally, a site-specific description of each of the three drain-
ages identified for detailed analysis is provided. These descriptions
include discussions of the amount and type of development, land use and
ownership and recreation use occurring in the area.
122
-------
TABLE 26
SPECIES AND NUMBERS OF FISH CAUGHT PER 100 METERS
IN RECENT STUDIES OF BEAR BUTTE CREEK, SOUTH DAKOTA
STATION
Bl
B2
SPECIES
September 1984
Long-nose dace
Rhinichthys cataractae
Mountain sucker
Catostomus platyrhynchus
White sucker
Catostomus commersoni
June 1985
Long-nose dace
Rhinichthys cataractae
Mountain sucker
Catostomus platyrhynchus
White sucker
Catostomus commersoni
"unknown minnow"
Source: South Dakota Department of Game, Fish and parks (1986)
B3
B4
no
fish
numerous
dace"
65
58
1
123
-------
Regional Overview
Lawrence County is located in the extreme west-central part of the
State, sharing its western boundary with Wyoming and lying midway
between South Dakota's northern and southern boundaries. Contiguous to
Lawrence County are Butte, Meade, and Pennington Counties; the latter
is also equivalent to the Rapid City Metropolitan Statistical Area
(Figure 17). The four counties are part of a seven-county area com-
prising the Black Hills Council of Local Governments (BHCLG), a region-
al planning and service agency.
In the following discussion, however, selected socioeconomic data
are provided for only Lawrence, Meade, and Pennington Counties with
emphasis focused on Lawrence County. Historical and present economic,
social and political links between these counties provide a common
denominator. Yet, at the same time there is a substantial amount of
variation in socioeconomic factors among the three counties, which must
be understood in order to evaluate the potential impacts of future
mining activity in the region.
In its earliest period of economic development, the Black Hills
region attracted settlers and prospectors interested in exploiting the
natural resources of gold and other minerals, and in farming. The
first recorded evidence of the area's rich mineral deposits occurred in
1834, with a find by a group of seven individuals. However, after
discovering gold, the party was apparently killed by the Indian inhabi-
tants of the area. Subsequently, over forty years passed until the
Gold Rush of 1876 brought thousands of prospectors and settlers to the
area, forever changing its future (Brady and Chichester, 1969). Since
the postwar period, the economic base of the region has expanded,
although some parts of the region, such as Lawrence County, continue to
rely heavily on mining or agriculture.
Growth in government, trade, services, and manufacturing over the
last half-century has resulted in a moderate level of diversification
in the Black Hills Region economy. The location of the Ellsworth Air
Force Base 13 kilometers (8 miles) east of Rapid City, as well as other
124
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FIGURE 17
SOCIOECONOMIC FEATURES
US 8
US 85
Newcastle
Belle Fourche
B U T T E
Mt. Rushmore
National Memon'al
Custer
State Park
LEGEND
COUNTY BOUNDARIES
NATIONAL AND STATE
PARKS AND MEMORIALS
BLACK HILLS
NATIONAL FOREST
MAJOR HIGHWAYS
Km
15
125
-------
Federal government agencies throughout the region, has pumped millions
of dollars into the local economy. Construction of Interstate 90 and
the growth of population centers in the western north-central United
States have enhanced the function of the Rapid City metropolitan
statistical area as a trade and service center for western South Dakota
and surrounding areas of Wyoming, Montana, North Dakota, and Nebraska.
Also, the numerous regional tourist attractions, including the Mount
Rushmore National Memorial, Badlands National Monument, Wind Cave
National Park, and Jewel Cave National Monument have fueled the growth
of the local tourist industry (Black Hills Council of Local Govern-
ments, 1984). Furthermore, a substantial portion of the lands within
the region, including over one-half of Lawrence County, are Federal
lands administratively designated as part of the Black Hills National
Forest. The forest supports a variety of recreation, timber harvest-
ing, mining and other multiple-use activities (U.S. Forest Service,
1983a).
Population
Table 27 compares population trends for Lawrence County with its
neighboring counties and the entire State for the period 1960 to 1984.
As shown, poplation growth within the three counties has consistently
exceeded that experienced by the State as a whole. While the statewide
population declined between 1960 and 1970, all three counties experi-
enced population increases. From 1970 to 1980, the combined population
growth of the region accounted for nearly 62 percent of the statewide
growth. Based on the 1984 population estimates, the disproportionate
growth trends are continuing, with 40 percent of the statewide growth
accounted for by the changes in this region.
As shown in Table 27, Lawrence County, with an estimated 19,200
residents in 1984, currently ranks seventh of the 66 counties in South
Dakota with respect to population. Between 1970 and 1980, the county's
population increased less rapidly than that of its neighbors and only
slightly faster than the state as a whole. Since 1980, Lawrence,
126
-------
County's population has grown at a faster rate than that of either the
State's or Meade County but slower than that of the more urbanized
Pennington County.
TABLE 27
POPULATION TRENDS IN BLACK HILLS REGION COUNTIES
1960
South Dakota 680,514
1970
1980
1984
1984 Compound Annual
State Percent Change
Rank 1970-80 1980-84
Lawrence
County
17,075
665,507 690,786
17,453 18,339
705,800 — 0.3 0.5
19,200 7th 0.5 1.2
Meade County 12,044
Pennington
County
58,195
17,020
59,349
20,717
70,361
21,500
74,700
6th
2nd
2.0
1.7
0.9
1.5
Source: U.S. Bureau of Economic Analysis, 1986a; U.S. Bureau of the
Census, 1982.
Employment
Since 1970, both statewide and regional employment trends have
generally coincided with the growth in population, increasing constant-
ly over the period (Table 28). However, the relative growth in employ-
ment has been substantially higher than the population growth; for
example, total employment in Pennington County increased by nearly
5,200 jobs between 1980 and 1984, compared to a population growth of
only 4,340 persons. Although not as dramatic, similar trends of
disproportionate employment growth have occurred in both Lawrence and
Meade Counties, as well as statewide, since 1970. The primary causes
for these differences are a general increase in the labor force parti-
cipation rates among the adult population and the declining average
household size. Both of these factors tend to increase the employment
to population ratios.
127
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TABLE 28
EMPLOYMENT TRENDS IN BLACK HILLS REGION COUNTIES
Compound Annual
1970
296,679
6,352
4,289
29,338
1980
348,993
8,639
5,439
42,255
1984
359,252
8,992
5,745
47,443
Percent
1970-1980
1.6
3.6
2.7
4.4
Change
1980-1984
0,8
1.0
1.4
3.1
South Dakota
Lawrence County
Meade County
Source: Bureau of Economic Analysis, 1986a; U.S. Bureau of the
Census, 1982.
Growth in employment in Lawrence County has kept pace with growth
in population over the 1980 to 1984 period. However, total employment
has not grown as quickly in Lawrence County as in its neighboring coun-
ties, although the absolute change of 300 to 400 jobs was comparable in
Lawrence and Meade Counties. The strong growth in Pennington County
reflects its expanded role as a regional trade and service center,
especially for the surrounding energy development regions of Wyoming,
Montana, and North Dakota, and the increasing diversification of its
economic base into manufacturing (L. Meredith, Black Hills Council of
Local Governments, personal communication, 1986). Employment growth in
Lawrence and Meade Counties has been led by increased service sector
employment catering to the local tourism and recreation industries.
As is also evident from Table 28, employment growth between 1980
and 1984 has slowed considerably since the 1970 to 1980 period, when
average annual growth rates ranged between 2.7 and 4.4 percent. These
changes have been brought about as a result of a stabilization or de-
cline of other traditional growth sectors of the local economy, espe-
cially government and mining.
Personal Income
The distribution of personal income earnings in each of the three
counties and the state is shown for 1984 in Table 29. In both Penning-
ton County and South Dakota, the services sector provides the highest
128
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TABLE 29
COMPOSITION OF TOTAL PERSONAL INCOME,
FOR BLACK HILLS COUNTIES AND SOUTH DAKOTA, 1984
PERSONAL INCOME BY SOURCE:
(thousands of dollars)
Total Earnings by 1 Place of Work
Adjustments for Non-earnings
Income
Total Personal Income by Place
of Residence
PER CAPITA PESONAL INCOME:
South Dakota
$5,134,942
2,561,178
$7,696,120
$ 10,904
Lawrence County
$135,737
63,706
$199,443
$ 10,400
Meade County
$ 77,442
134,529
$211,971
$ 9,845
Pennington County
$707,608
149,208
$856,816
$ 11,465
EARNINGS OF PLACE OF WORK BY INDUSTRY:
(thousands of dollars)
Farm
Nonfarm
Private
AFFOa/
Mining
Construction
Manufacturing
TCUC/
Wholesale Trade
Retail Trade
FIRE '
Services
Government
Federal, Civilian
Military
State and Local
Total Earnings by Place
of work
Amount
$ 828,274
4,306,668
3,356,808
26,341
79,744
245,042
556,436
364,177
359,638
526,393
273,990
925,047
949,860
238,440
137,785
573,635
Percent
of Total
16.1
83.9
65.4
0.5
1.6
4.8
10.8
7.1
7.0
10.3
5.3
18.0
18.5
4.6
2.7
11.2
Amount
$ 4,362
13,376
114,003
76
53,264
5,255
12,361
5,384
3,492
13,276
3,552
17,343
19,372
3,635
590
15,147
Percent
of Total
1.7
98.3
84.0
0.1
39.2
3.9
9.1
4.0
2.6
9.8
2.6
12.8
14.3
2.7
0.4
11.2
Amount
$13,739
63,703
36,379
(D)b/
(D)
4,282
5,591
2,693
3,815
6,596
1,884
10,493
27,324
18,178
522
8,624
Percent
of Total
17.7
82.3
47.0
—
—
5.5
7.2
3.5
4.9
8.5
2.4
13.5
35.3
23.5
0.7
11.1
Amount
$ 13,847
693,761
476,810
1,437
7,911
50,997
63,744
51,538
41,980
89,324
31,298
138,586
216,951
37,124
117,603
62,224
Percent
of Total
2.0
98.0
67.4
0.2
1.1
7.2
9.0
7.3
5.9
12.6
4.4
19.6
30.7
5.2
16.6
8.8
$5,134,942 100.0
$135,737 100.0
(Continued)
$77,442 100.0
$707,608 100.0
-------
TABLE 29 (Continued)
Note: For each location, only the sectors accounting for the greatest shares of local personal income are included.
a/ Agricultural Service, Fishing and Other
b/ (D) - data not reported to prevent disclosure of confidential information. Total employment within the two
industries is 115 or 2.0 percenjt of the total.
c/ Transportation, Communication, and Utilities.
d/ Finance, Insurance, and Real Estate.
Source: U.S. Bureau of Economic Analysis, 1986.
-------
share of income earnings. Services is the single largest employment
sector in both these areas. Meade County is most heavily dependent on
the Federal civilian government employment as a source of personal
income; this sector provides about 23.5 percent of the county's total
income compared to only 12.5 percent of total county employment. In
Lawrence County, a very large share of all personal income is generated
by the mining industry. The total mining earnings of over $53 million
in 1984 accounted for nearly $4.00 of every $10.00 earned in the
county. Yet, only about 18 percent of the total employment occurs in
this sector.
The three counties also show some variation in per capita income
earnings. In 1984, residents of Pennington County, with an average of
$11,468, enjoyed the highest per capita incomes in the area. In
Lawrence County, per capita incomes were considerably lower, averaging
$10,400. This was also below the average income in the State that year
of $10,904. Meade County residents had even lower average incomes of
$9,845 per capita.
Unemployment
Average unemployment rates in South Dakota and in the three-county
Black Hills region have been low relative to national jobless rates
during the 1980 to 1985 period, as shown in Table 30. Within the
region, there have been some differences among the counties' rates, but
these have been relatively minor. Still, unemployment in Lawrence
County has tended to be slightly higher than in Meade and Pennington
counties or the State.
131
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TABLE 30
AVERAGE ANNUAL UNEMPLOYMENT RATES IN BLACK HILLS
REGION COUNTIES, SOUTH DAKOTA, AND THE UNITED STATES
Percent of the Labor Force Unemployed
1980 1981 1982 1983 1984 1985
United States 7.1 7.6 9.7 9.6 7.5 7.1
South Dakota 4.8 5.1 5.5 5.4 4.4 5.2
Lawrence County 5.1 5.0 6.1 5.3 4.8 5.4
Meade County 5.1 4.4 4.8 5.5 3.5 4.4
Pennlngton County 5.6 5.0 5.1 5.1 4.3 5.3
Source: U.S. Bureau of Economic Analysis, 1986b.
Economic Base
There are both similarities and differences among the three coun-
ties with respect to composition of the economic base. The similari-
ties stem from common economic links to tourism, outdoor recreation,
timbering/lumber and wood processing and the Federal government.
Natural resource availability, transportation networks and local com-
munity roles as trade and service centers account for many of the dif-
ferences.
As shown in Table 31, all three counties have relatively high
proportions of employment in the services, retail trade and manufactur-
ing industries. These industries encompass the types of business asso-
ciated with tourism and lumber and wood processing. Although the share
of Meade County's total employment appears to be below the levels in
the other counties or the state, it is in fact comparable to that for
the other jurisdictions if only nonfarm employment is considered; the
high percentage of farm employment skews the proportion in the nonfarm
industries. The importance of tourism in the local economies Is illus-
trated by the high share of total employment in retail trade and ser-
vices and by a recent study which revealed that total visitor-related
spending accounted for about 18 percent of all taxable sales in
Lawrence and Pennington counties between September 1983 and August
132
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TABLE 31
COMPOSITION OF EMPLOYMENT FOR BLACK HILLS REGION COUNTIES, 1984
South Dakota
Percent
Employment of Total
Lawrence County
Percent
Employment of Total
Meads County Pennlngton County
Percent Percent
Employment of Total Employment of Total
By Industry:
Farm
Nonfarra
Private
AFFO
Mining
Construction
Manufacturing
TCUC/
Wholesale trade
Retail Trade
FIRE
Services
Government
Federal, Civilian
Military
State & Local
TOTAL EMPLOYMENT
46,868
312,374
248,478
3,559
3,207
15,704
30,264
15,232
18,422
61,030
21,090
79,151
63,896
10,436
10,710
42,750
359,252
13.0
87.0
69.2
1.0
0.9
4.4
8.4
4.2
5.1
17.0
6.2
22.0
17.8
2.9
3.0
11.9
100.0
269
8,723
7,251
158
1,731
379
710
270
204
1,590
418
1,891
1,472
169
121
1,182
8,992
3.0
97.0
80.6
1.8
18.1
4.2
7.9
3.0
2.3
17.7
4.6
21.0
16.4
1.9
1.3
13.1
100.0
923
4»822
3,322 /
(D)D/
(D)
289
375
159
183
855
247
1,099
1,500
716
112
672
5,745
16.1
83.9
57.8
1.0
1.0
5.0
6.5
2.8
3.2
14.9
4.3
19.1
26.1
12.5
1.9
11.7
100.0
661
46,782
34,184
313
526
2,745
3,959
2,130
2,000
8,802
2,933
10,776
12,598
1,622
6,743
4,233
47,443
1.4
98.6
72.1
0.7
1.1
5.8
8.3
4.5
4.2
18.6
6.2
22.7
26.6
3.4
14.2
8.9
100.0
a/ Agricultural Service, Forestry, Fishing, and Other.
b/ (D) - data not reported to prevent disclosure of confidential information.
industries is 115 or 2.0 percent of the total.
c/ Transportation, Communication, and Utilities
d/ Finance, Insurance, and Real Estate
Source: U.S. Bureau of Economic Analysis, 1986a.
Total employment within the two
-------
1985. During the same period, one-eighth (12.5 percent) of all taxable
sales in Meade County was attributed to visitor-related spending
(University of South Dakota, 1986).
As also shown in Table 31, some dissimilarities exist. Retail and
service employment, while high in all counties, was especially high in
Pennington County. This is due to the role of Rapid City as a regional
trade and service center serving the western half of South Dakota and
parts of four neighboring states.
Employment in Lawrence County is much more highly concentrated in
the mining industry than either of its neighbors or the state as a
whole. The local mining sector accounts for 18 percent of all local
jobs in Lawrence County and over half of the total mining jobs in the
state, compared to 2 percent or less in Meade and Pennington counties
and South Dakota. The majority of these jobs are associated with the
Homestake Mining Company's operations based in Lead. More recently,
employment at Homestake has declined, but some of the decline was off-
set by other mining exploration and development operations in Lawrence
County, for example, Wharf Resources heap leach operation southwest of
Lead, which employs about 100 persons (Mountain International, Inc.,
1985; H. Scholz, Wharf Resources, Ltd., personal communication, 198).
In contrast to the dependence on mining in Lawrence County, the
economies of both Pennington and Meade Counties are more heavily con-
centrated in Federal government employment. Ellsworth Air Force Base,
a strategic military facility serving as a base for part of the
nation's long-range B-52 and B-l bomber fleets, is located in northern
Pennington County, near the Meade County border. Meade County hosts a
major Veteran's Administration Hospital, providing substantial Federal
civilian employment.
As mentioned earlier, the other primary difference in local eco-
nomic composition is the concentration of farming employment in Meade
County, accounting for over 16 percent of the total local employment.
Although the extent of local impacts associated with the current
nationwide agriculture crisis is uncertain, farming in Meade County
134
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had been bucking national trends. According to the 1982 Census of
Agriculture, when the number of farms and acreage in farm lands de-
clined nationally and in the state between 1978 and 1982, both in-
creased in Meade County. Total acreage of land in farms in Lawrence
and Pennington Counties declined during the same five-year period (U.S.
Bureau of the Census, 1982).
Tourism and Recreation
As previously mentioned, tourism and recreation have important
roles in the local economy. Natural and man-made features and recrea-
tional opportunities abound in the region. These include public sites,
such as the Mt. Rushmore National Monument, national and state parks
and the Black Hills National Forest, as well as the historical gold
mining districts of Lead, Deadwood and Custer. Numerous streams and
lakes, as well as developed Forest Service picnic areas and campgrounds
help support the region's tourism industry and provide recreation op-
portunities for area residents over much of the year. Among the more
popular activities are hunting primarily for deer and game birds, fish-
ing, hiking, camping and 4-wheel drive touring on the many mining and
logging roads throughout the area (U.S. Forest Service, 1983a; P. Mock,
Black Hills National Forest, personal communication, 1986).
Tourism in the three county region is based primarily on visits to
a number of natural and historical sites rather than on business or
convention related trips. Information on annual numbers of visits to
five major sites in the area is shown for three recent years in Table
32. As is indicated, the number of visits to each of the individual
sites has fluctuated over the 1983 to 1985 period. Changes in the
number of visitors range from an increase of 44 percent at Jewel Cave
to a decrease of over seven percent at Badlands National Monument.
However, the importance of tourism is obvious as combined annual visits
to the sites in the region have totaled over five million for each of
the years between 1983 and 1985 and the number of visits has increased
nearly two percent.
135
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TABLE 32
NUMBER OF ANNUAL VISITS TO SELECTED REGIONAL TOURIST
SITES IN SOUTHWESTERN SOUTH DAKOTA
1983-1985
1983 1984 1985 Percent Change
Badlands 1,038,981 1,125,675 962,242 -7.4
(Pennington County)
Jewel Cave 89,645 102,000 129,076 44.0
(Custer County)
Mount Rushmore 1,983,710 1,886,790 2,112,281 6.5
(Pennington County)
Wind Cave 1,015,144 1,037,735 963,811 -5.1
(Custer County)
Custer 1,022,553 994,418 1,072,907 4.9
(Custer County)
TOTAL 5,150,033 5,146,618 5,240,317 1.8
Source: State of South Dakota, 1986b.
Although three of these tourist sites are located in Custer County
which is Pennington County's neighbor to the south, and none are in
Lawrence County, travel to and from these sites flows through the three
county region, contributing economic benefits. This is especially true
for northern Lawrence County since a major transportation artery,
Interstate 90, passes through it as do two scenic loops, U.S. Highways
85 and 385; these pass through the historic mining district surrounding
the towns of Deadwood, Lead and Central City. In addition, there are
several small ski areas in Lawrence County which account for a portion
of the tourism activity in the region.
Historically, the primary tourism and recreation season has been
during the summer and early fall. While this is still true, there is
an increasing emphasis by local chambers of commerce, economic develop-
ment agencies and tourism-oriented establishments to promote winter
recreation opportunities (D. Schenkeir, Deadwood-Lead Area Chamber of
Commerce, personal communication, 1986). Downhill and cross-country
skiing and snowmobiling opportunities are being promoted with some
136
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success. For example, Figure 18 shows the western portion of the South
Dakota Snowmobile Trail Program which represents nearly one-half of all
the existing trails in the state (State of South Dakota, 1985). Not
shown on the map are the existing downhill ski areas located about 8
kilometers (five miles) southwest of Lead which attract skiers from
throughout the region.
Primary Area of Socioeconomic Influence
As portrayed above, Lawrence, Meade, and Pennington Counties are
linked by economic ties and geographic location. Therefore, their
economies are subject to many of the same influences. However, within
the context of potential heap leach gold operations, the majority of
impacts are expected to be much more localized. Based on the geograph-
ic area of mineralization and present mineral exploitation activities,
as well as the residency patterns among persons currently employed at
the Homestake and Wharf Resources operations, the primary area of in-
fluence for socioeconomic impacts will be the northern portions of
Lawrence County, especially the towns of Lead and Deadwood and nearby
surrounding environs. The remainder of this section will provide a
brief description of key socioeconomic characteristics within the pri-
mary area of influence.
Over 60 percent of the population of Lawrence County resides in
three incorporated municipalities: Spearfish, Lead, and Deadwood. In
addition, approximately 1,100 to 1,200 persons live in the communities
of Whitewood and St. Onge, both located in the northern portion of the
county. The remaining inhabitants reside in unincorporated areas of
the county, principally surrounding the three major towns and in small
clusters of homes and farms scattered throughout the county. Most of
the farms are located in the northern one-third of the county where the
land is more conducive to agriculture, while those homes in the Black
Hills area tend to be located in the bottom lands along the major
streams in the county. Population data for the three towns for the
period 1960 to 1985 is shown in Table 33 along with the rate of change
in each over the past fifteen years.
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FIGURE 18
BLACK HILLS SNOWMOBILE TRAIL SYSTEM
Tomahawk Country Club —
\- v -! "~r-*v- -
rownsville Store—l/V rx "
- •
LEGEND
Parking Areas,'Restrooms
Warming Shelters
'"x?
iJ*i No Snowrnobiling Areas
Snowmobile Equipmenc Rental
TRAIL KEY
Trad 1. . . 85 miles ••
Trail! A- .. 4 miles ••
Trail 2 56 miles ••
Trail 2A . . . 5 miles ••
Trail 2 B.. . 2 miles •
Trail 3 .12 miles ••
Trail 3A 6 niiles ••
Trail 4 . 9 rrules •
Trail 1A ;) miles •
i:| miles ••
Trail "> A 1 ,,,,1,. mm
Trail li 6
Trail 7 r> miles
Trail M H niiles
TOTAL '.T ,,,i/f.s
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TABLE 33
POPULATION CHANGE, LAWRENCE COUNTY
AND SELECTED TOWNS, 1960 TO 1985
Annual Percent Change
1960 1970 1980 1985 1970-1980 1980-1985
LAWRENCE COUNTY 17,075 17,453 18,339 19,200 0.5 0.1
Spearf ish
Lead
Dead wood
3,682
6,211
3,045
4,661
5,420
2,409
5,251
4,330
2,035
5,780
4,180
1,820
1.2
-2.2
-1.7
1.9
-0.7
-2.2
Source: U.S. Bureau of the Census, 1982; Black Hills Council of
Local Governments, 1984.
As indicated above, Lawrence County as a whole experienced slow
but steady population growth during the 1970's and the early 1980's.
However, the majority of this growth occurred in and around Spearfish.
During both the 1970's and the first half of the 1980's, Lead and Dead-
wood lost population, continuing a trend dating back to before 1960.
There are five underlying causes of these shifts in local populations.
First, changes have occurred in the location of local employment op-
portunities. While mining employment has been declining steadily,
thereby affecting Lead and Deadwood, employment in other sectors,
especially in the manufacturing and services industries concentrated
around Spearfish, have been increasing. Second, changes in residential
preferences and increased transportation mobility have resulted in an
increased tendency for persons employed in Lead and Deadwood to reside
elsewhere and commute to work. For example, in the four-year period
1979 to 1983, the proportion of Homestake employees residing in Spear-
fish increased from seven to 11 percent. A comparable number of Home-
stake employees reside in nearby Sturgis (Meade County), a town very
similar to Spearfish. Both have populations of over 5,000, are located
on Interstate 90 offering excellent access to Rapid City, have a higher
level of retail trade and personal consumer services available, and are
located within 30 to 40 kilometers (20 to 25 miles) driving distance to
the mines.
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Fourth, the terrain, topography and land ownership have acted as
natural constraints to local growth and development. Both Lead and
Deadwood are located in areas of steep slopes, limited flat lands and
highway transportation corridors established along stream drainages,
and surrounded by areas of potentially valuable mineralization depos-
its. Thus, these communities have been limited in their ability to
expand their boundaries or tax bases to respond to changing conditions
and the desires for higher levels of public services (C. Koerner,
Lawrence County Planner, personal communication, 1986; D. Mueller,
Black Hills Council of Local Governments, personal communication, 1986;
H. Lux, City of Lead, personal communication, 1986). By contrast, both
Spearfish and Sturgis are located in areas of gently rolling hills more
conducive to the provision of services and today's tastes in housing.
As mentioned above, there is a certain vicious circularity to these
trends. Unless something occurs to break the cycle, further population
declines might be expected in Lead and Deadwood, with more growth fo-
cused on Spearfish and possibly Sturgis.
Finally, Spearfish has been attracting a number of new residents
from among the ranks of retired persons. It offers a temperate cli-
mate, essential levels of retail trade and services and recreation
opportunities, as well as easy access to Rapid City.
Employment and Economic Base
The relative concentration of employment in major economic sectors
in Lawrence County has shifted somewhat over the 1980 to 1984 period.
The composition of local employment in the county over this period is
presented in Table 34.
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TABLE 34
COMPOSITION OF EMPLOYMENT IN
LAWRENCE COUNTY, 1980 to 1984
Manufacturing
Mining
Retail Trade
Services
State/Local
Government
All Others
TOTAL EMPLOYMENT
1980
481
1,763
1,581
1,698
1,214
1981
477
1,776
1,635
1,669
1,201
1982
604
1,655
1,559
1,687
1,153
1983
666
1,617
1,579
1,781
1,159
1984
710
1,631
1,590
1,891
1,182
Change
1980-84
+229
-132
+ 9
+193
- 32
1,902 1,986 1,938 1,981 1,988
8,639 8,744 8,596 8,788 8,992
86
+353
Source: U.S. Bureau of Economic Analysis, 1986a.
The major shifts have been a decline in total mining employment,
offset by increases in the manufacturing and services industries. The
former change has been in response to general market conditions for
precious and industrial metals, while the latter reflects increased
lumber and wood processing and tourism.
These changes have affected each of the three towns differentially
with many of the impacts visibly apparent. Recent and ongoing commer-
cial and residential construction are readily evident in Spearfish,
compared with little new construction in the other communities. Al-
though there are many hotels, motels and restaurants to serve tourists,
there are also many establishments to serve the local population, local
commercial business and the agricultural industries. The most recent
new construction in Deadwood appears to be a motel, a medical office
extension of the hospital and ongoing major highway construction
through town to accommodate the heavy volume of tourist traffic.
Recently the J.C. Penney retail outlet, the Montgomery Ward mail-order
store and an appliance store have closed in Deadwood. Such establish-
ments typically rely on the local residential population to support
their operations. The base of such local market-serving establishments
continues to decline, being replaced by specialty goods, novelty and
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convenience goods stores. Meanwhile, in Lead, the retail and commer-
cial base is virtually nonexistent. There are probably fewer than 20
establishments presently located in Lead. These include one major
grocery store; several smaller convenience outlets for gas, liquor and
food; several cafes and restaurants; three or four small, older motels;
two banks; and a number of miscellaneous stores. In addition, at least
three mining companies have offices in Lead, along with several profes-
sional offices for dentists, doctors, attorneys, and accountants.
However, for a community with a population of over 4,000 inhabitants,
this barely even satisfies the essential needs (personal observation,
1986).
The differences are also reflected in local attitudes towards
economic development. The Black Hills Council of Local Governments and
Northern Hills Community Development, Inc. have targeted Spearfish as a
potential development center and are actively pursuing a program of
economic diversification. Lead is currently participating in a multi-
faceted program involving the construction of a shopping center, a
motel and small group conference center and new single-family resi-
dences. This is being done not so much to achieve new growth, but to
stem further declines (H. Lux, City of Lead, personal communication,
1986). Meanwhile, a number of tourist-oriented proposals are being
considered in the Deadwood area. These include an integrated western-
theme recreation/amusement park, combined with a steam-powered scenic
excursion railroad and an operating liquor distillery (D. Schenkein,
Deadwood-Lead Area Chamber of Commerce, personal communication, 1986).
Housing
The housing stock within the primary area of influence reflects
recent economic trends. According to 1980 census data, more than ten
percent of the existing year-round housing stock, or 9.5 percent of the
total housing, was vacant (Table 35). A total of 463 seasonal units,
or 5.8 percent of the total, were also reported. These were primarily
summer cabins located in the limited bottom lands along the larger
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creeks and streams In the area. Access to most of these units Is pro-
vided via Forest Service or county roads, many of which are impassible
during the winter.
TABLE 35
SELECTED 1980 HOUSING DATA IN
LAWRENCE COUNTY, DEADWOOD, AND LEAD
Number of Units Percent of Total
Lawrence County:
Total Housing Units 7,955 100.0
Seasonal Units 463 5.8
Year-round Occupied Units 6,738 84.7
Year-round Vacant Units 754 9.5
Lead:
Total Housing Units 1,876 100.0 .
Year-round Occupied Units 1,655 88.2a/
Year-round Vacant Units 208 11.1
Deadwood:
Total Housing Units 949 100.0 ,
Year-round Occupied Units 827 87.1
Year-round Vacant Units 120 12.6
a/
The sum of year-round occupied and vacant do not equal the total
housing stock because seasonal units are included in the total.
Source: U.S. Bureau of the Census, 1982.
The reported vacancy rates in Lead and Deadwood were higher than
the county average at 11.1 and 12.6 percent, respectively. In addition
30 percent of the occupied housing in Lead and 42 percent of that in
Deadwood were renter occupied. Other census data also showed much of
the local housing stock to be older structures in fair to poor condi-
tion.
According to local officials, this data illustrates one of the
more critical problems facing the area, namely, lack of suitable
housing. Several factors combine to create the problems. First is the
age and general condition of the existing stock in Lead and Deadwood.
The homes tend to be small, built in close proximity to each other and
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due to the steep terrain, they tend to have small yards, no garages and
no room for expansion. The steep terrain also limits the amount of
land suitable for development. Thus, since 1980, little new residen-
tial construction has occurred in Lead and Deadwood and the local
housing conditions, if anything, have deteriorated as the local popula-
tion has declined. Consequently, more household Interest is shifting
towards residing in communities such as Spearfish and Sturgis which do
not face the same constraints and into unincorporated areas of the
county (C. Koerner, Lawrence County Planner, personal communication,
1986; H. Lux, City of Lead, personal communication, 1986).
Another problem is the land ownership patterns surrounding the
towns. Most of the land is public and not available for residential
development and much of the private lands are potential mining claims
in areas of known mineralization where the surface and/or mineral
rights owners want to maintain the option of future mining activity.
Finally, the Lawrence County Comprehensive Plan identified a lack
of soils suitable for industrial septic systems as a major constraint
to residential development in the outlying portions of the county and
as a possible contribution to water quality problems. Only 10 to 30
percent of the total area in the Lead-Deadwood vicinity is identified
as being suitable for septic system installation. Thus, even if the
local employment picture remains stable, the towns' population and tax
base may continue to decline (Brady and Chichester, 1969).
As part of the local effort to stem these declines and address the
housing problems, several recent initiatives have been undertaken.
First, the town of Lead acquired abandoned railroad right-of-way within
the town, part of which will be made available for residential con-
struction. Secondly, both Lead and Deadwood have recently annexed
property in an area lying on U.S. Highway 85/385 between the two
cities. Historically, this land remained unincorporated because of the
difficulty in providing water and sanitation service. However, as a
result of the formation of the Lead-Deadwood Sanitation District, which
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has just completed a major capital improvement program, the area can
now be served, providing some opportunity for new development. The
district's long-term goal is to extend its service area even farther.
Community Services and Infrastructure
Many components of the local public infrastructure and service
delivery systems currently have excess capacity available due to the
long-term trend of declining service area populations. In several
instances, infrastructure conditions are substandard due to the declin-
ing population, tax base and the need to address higher priorities. On
the other hand, recent investments and other actions have resulted in
modern, up-to-date facilities being available. A brief description of
each of the major public systems and services is provided below.
Schools. The consolidated Lead-Deadwood School District No. 40-1
is responsible for primary and secondary education in the area. The
jurisdiction covers virtually the entire southern half of the county.
The current district was formed in 1972 by the consolidation of
the formerly independent Lead and Deadwood school districts. Many
residents opposed the consolidation, but it was brought about by
economic necessity to maintain efficient operations and a full range of
programs in the face of declining enrollments. Even since the consoli-
dation occurred, the district's enrollment has declined by over 1,000
students. The combined current enrollment was 1,396 students during
the 1985-86 school year. Enrollments in grades K-6 accounted for 788
of the total, with junior/senior high enrollment of 608 students.
Continuing declines in enrollment and a fire at the Deadwood
junior high school building in 1985 have required an ongoing series of
adjustments in the use of facilities. Two elementary schools are
presently operated by the district, one each in Lead and Deadwood and
the high school is in Lead. Following last year's fire, the junior
high and high school student bodies were combined In the high school
building. The junior high school is In the process of being renovated
and modernized. When completed, the structure will house the junior
and senior high school and the current high school will be vacated.
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According to the district superintendent, the system could accom-
modate up to 200 additional students without a significant adverse
impact. Additional staff would have to be hired and additional capac-
ity put into use. This was not perceived as negative, but rather a
positive impact of growth (R. Scheurman, Lead-Deadwood Public Schools,
personal communication, 1986).
Law Enforcement. Law enforcement in the area is provided by four
agencies: the Lawrence County Sheriff, Lead Police Department, Dead-
wood Police Department and South Dakota Highway Patrol. The Lawrence
County Sheriff's Department, based in Deadwood, is the principal law
enforcement agency for the county. The Sheriff's department is housed
in a relatively new structure providing offices, communications center,
and detention facilities for up to 40 inmates. Some excess office
space in the basement is currently used by other county agencies due to
the condemnation of the county building. Current staffing includes the
Sheriff, five deputies, a bailiff and a paper server. In addition to
its own duties, the Sheriff's department provides dispatch services for
the Highway Patrol stationed in the area and provides detention capac-
ity for the patrol and local municipalities. According to the Lawrence
County Sheriff's Department, current staffing and services are rated as
adequate with no critical needs.
The Lead Police Department has six full-time personnel and is
housed in the City Hall. The department's jurisdiction includes the
incorporated municipal limits. According to the Lead Comprehensive
Plan, there is sufficient space in City Hall, although some upgrading
of mechanical systems and additional parking spaces are needed. The
Lead Police Department is rated as adequate (City of Lead, 1985; H.
Lux, City of Lead, personal communication, 1986).
The Deadwood Police Department has five full-time staff, a reduc-
tion of one officer in the last year due to budget cuts. The offices
are located in Deadwood City Hall, a converted railroad depot, that
also houses the fire department and other city offices. The Deadwood
Police Chief indicates that the adequacy of local law enforcement is
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being maintained but additional staff, updated patrol vehicles and
expanded office facilities are all needed (D. Heidzig, Deadwood Police
Department, personal communication, 1986).
Two officers of the South Dakota Highway Patrol are based in
Deadwood, with other officers stationed in Spearfish and other sur-
rounding communities. The Highway Patrol's major areas of responsi-
bility are law enforcement on Interstate 90 and the various U.S. and
state highways in the region according to the Lawrence County Sheriff's
Department. No assessment of adequacy is available.
Fire Protection. Municipal fire protection in the area is pro-
vided by the Lead and Deadwood Fire Departments. Each of these depart-
ments serves not only incorporated limits, but also the surrounding
rural areas. Both are primarily volunteer departments, supplemented by
several paid full-time professionals. The paid professionals insure
prompt emergency response during the daytime when volunteer response
can be uncertain. Both departments are housed in their respective City
Halls and could benefit from additional space, especially in Deadwood.
The Lead Fire Department is equipped with three major apparatus:
a 1986 combination ladder, hose and pumper, a 1972 pumper and a 1979
Mini-Attack quick response pumper. In addition, it maintains several
older 4-wheel drive brush/forest fire units. The Deadwood Fire Depart-
ment is also equipped with three major apparatus: an aerial/ladder
truck and two combination pumpers. The ages of these vehicles is not
known; however, the Fire Chief indicated that the City and department
were saving to acquire a new combination pumper to replace the oldest
unit. The Deadwood Fire Department also maintains a smaller 4-wheel
drive brush/forest fire unit, is building a similar unit and operates a
communications and equipment van.
Since there is no fire protection district established to serve
the outlying areas of the county, the Lawrence County Fire Advisory
Board assists the established fire departments to develop expanded
capacity to deal with the problems of firefighting in rural areas. The
primary problem is a lack of water supply. Presently, a 2,500 gallon
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capacity tanker truck, owned by the advisory board, is staffed, oper-
ated, and maintained by the Deadwood Fire Department. It is available
to respond to any fire location in the county. The advisory board is
in the process of acquiring another similar unit to serve the Lead-
Deadwood area.
Lead has a fire insurance rating of 6 and Deadwood has a rating of
8. Both departments are rated as adequate for current needs and any
foreseeable changes (J. Hood, Deadwood Fire Department, personal com-
munication, 1986; T. Mitzel, Lead Fire Department, personal communica-
tion, 1986).
Local municipal fire protection is supplemented by other depart-
ments in the region under a mutual aid assistance pact. These include
departments in the adjoining communities of Spearfish, Sturgis, and the
South Dakota Division of Forestry which maintains a forest management
and firefighting base outside Lead. For example, when the Deadwood
junior high school building burned in 1985, units from all of the above
either responded directly or provided coverage in other jurisdictions
which had dispatched their units to Deadwood.
Medical Care. Primary medical care in the area is provided by the
Northern Hills General Hospital and the Black Hills Medical Center.
These two facilities are located adjacent to one another in Deadwood.
As is true in other areas of public services, the Northern Hills
General Hospital emerged as the surviving entity following the consoli-
dation of two hospitals serving a declining market: one each in Lead
and Deadwood. As the local population continued in steady decline
during the 1960's and 1970's, the operations and maintenance of two
hospitals in a limited population service area became impractical. The
existing hospital was selected as a base of operations partially
because it was the larger facility and apparently the local physicians
supported its choice. The current capacity is 39 beds and it is
operating at an average occupancy of 40 percent. The hospital offers a
full-range of facilities including emergency room, radiology and
surgery (D. Thrall, Northern Hills General Hospital, personal communi-
cation, 1986).
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The Black Hills Medical Clinic is a recently completed modern
clinic, adjoining the hospital. The clinic houses most of the 11
physicians maintaining practices in the Lead-Deadwood area.
Several local officials rated the quality of medical care as
satisfactory and were not aware of any critical needs. In the event
that specialized care is required, Rapid City, a major regional medical
center, is located an hour's drive from Deadwood.
Ambulance service in the Lead-Deadwood area is provided by a
private firm in Lead. The service is available 24-hours a day, with
staffing done on an on-call basis. The service is funded by fees for
services and by an appropriation from Lawrence County. Recently the
services operator sought additional funding to upgrade existing capa-
bilities and purchase an additional ambulance.
Solid Wastes. The City of Lead contracts with a private operator
for residential solid waste collection and transport within the corpor-
ate limits. The City of Deadwood currently provides the service
directly, although it is presently considering implementing a system
similar to Lead's. Residents are then billed by the cities to recover
costs. In both communities, collection and transport for commercial
entities is done on an individual contract basis, as is residential
service in the outlying rural areas. Individuals in the outlying area
also have the option of hauling their solid waste to a landfill site
themselves.
There are two sanitary landfills currently serving the area: one
in Sturgis, the other in Belle Fourche. Much of the solid waste
collected in the area is being transported to the Belle Fourche site
because of its available capacity. At the current rate of filling, the
site has an estimated 50-year life remaining (K. Peterson, Belle
Fourche Sanitary Landfill, personal communication, 1986; H. Lux, City
of Lead, personal communication, 1986).
In addition to the sanitary landfills the cities of Lead and
Deadwood maintain a dump to the south of Lead off Yellow Creek Road
which is open to the public on a fee basis. Materials accepted are
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limited to metals and burnables. The cities utilize this site for
limited purposes such as disposal of refuse collected in the annual
spring trash pickup. The Homestake Mining Company and Black Hills
Power and Light also maintain private facilities in this area (H. Lux,
City of Lead, personal communication, 1986).
Water and Wastewater. Both Lead and Deadwood rely on the Home-
stake Mining Company for their water supplies. The municipalities
purchase the water from Homestake and bill the respective users,
operating the utilities on an enterprise basis. The company owns and
maintains the system serving Lead, while the Deadwood system Is munici-
pally owned.
Although both systems have areas of older, deteriorating distribu-
tion lines and less-than-desired pressure in isolated locations, both
report excess delivery capacity available and adequate storage to meet
peak daily demands and firefighting requirements. Some transmission
line Improvements and additional fire hydrant locations were recently
completed for the Deadwood system. Overall, these systems are adequate
to meet current demand and can accommodate additional growth In demand.
Wastewater treatment Is provided locally by the Lead-Deadwood
Sanitary District No. 1. The district completed its secondary treat-
ment facility in 1979 to address then existing problems of inadequate
treatment. During normal operations the system is operating at its
design capacity of 2.3 million gallons per day. The facility also
receives a major portion of storm flows from the portions of the
communities covered by storm drainage systems. However, at the present
time, no major expansions or improvements of the treatment capacity Is
planned according to the Lead-Deadwood Waste Water District. Some
consideration is being given to adding tertiary treatment, but the
timing of such improvements is uncertain. The primary influence in
determining facility needs is the service area population. Since the
formation of the district, little growth has occurred. Furthermore,
the district has been unsuccessful in convincing property owners
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located adjacent to the district and currently on individual septic
systems to join the district. As long as these two situations remain
unchanged, there will be little justification for increasing the
system's capacity.
Since the formation of the sanitary district, the highest priority
need in the area has been the replacement of the flume. The flume is a
large wood-construction conduit which carries sewage and storm sewage
from most of the community of Lead to the district's primary trans-
mission lines. The flume is over 80 years old and leaks badly. The
City of Lead is proceeding with a contract to replace the flume within
the next year. Once completed, no major system deficiencies will
remain, although the question of the wastewater treatment system's
ability to accommodate growth will remain (City of Lead, 1985; H. Lux,
City of Lead, personal communication, 1986).
County Roads. Based on the previous experience of the Lawrence
County Department of Highways any new heap leach gold mining and
processing operation in Lawrence County could be expected to have
impacts on the county road system, both during the construction and
operational phases of the mine. The level of impact would, of course,
depend on the location and nature of the mine operation.
In the past, road problems which have arisen have been dealt with
on a case-by-case basis with the raining companies generally participat-
ing either by assisting directly in construction and maintenance, by
sharing costs, or by providing materials, easements or engineering
assistance.
Without specific knowledge of where mining operations might occur
it is difficult for highway officials to anticipate what actual needs
might arise but it is possible to identify a few key road segments
which could potentially be affected by heap leach operations and assess
their current status:
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Gilt Edge Road (Forest Route 170). This is a jointly main-
tained road with the U.S. Forest Service. It runs from U.S.
Highway 385 to Forest Development Road 534 in the vicinity of
the Gild Edge permit area. The county currently maintains
the road for 1.1 kilometers (0.7 mile) from U.S. Highway 385.
Mining activity in the area would probably require at least
regraveling of this segment.
Yellow Greek Road. This is a jointly maintained road with
the Forest Service and Bureau of Land Management. The public
dump facility for Lead and Deadwood and private facilities of
the Homestake Mining Company and Black Hills Power and Light
are located off this road and, due to its heavy use by
various entities, maintenance has been on a shared basis.
The Maitland Road was rebuilt about a year ago from Central
City to the St. Joe American site. Heavy traffic on this
road due to travelers trying to avoid state highway construc-
tion east of Deadwood, combined with heavy equipment movement
in the area, has elicited complaints from residents about
noise and dust.
The Terry Gulch road had been planned for reconstruction next
year but this is currently on hold awaiting more information
on plans in the area by Moruya Gold Mines, Inc.
The Trojan Road serving the Wharf Resources Annie Creek mine
and a potential route to St. Joe American operations has
suffered subsidence problems possibly related to abandoned
underground workings and will probably require rebuilding at
some point.
The County Road and Bridge Department has typically been in a
reactive position with the limited information available about poten-
tial mine operations and limited resources of the department allowing
little lead time for planning road improvements (C. Williams, Lawrence
County Highway Department, personal communication, 1986).
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General Government. Most of the key public service delivery sys-
tems for the local governments and agencies are discussed separately.
However, in the local area of influence there exists one area of
concern that transcends the individual services and systems, that being
the needs for general administrative and operations facilities.
For many years, the local governments have been experiencing
either only modest population growth or actual declines. Their fiscal
resources have been comparably impacted. During the same time, infla-
tion has resulted in substantially greater pressure on the expenditures
budgets. Consequently, over time the local governments and public
agencies have sought ways to become more efficient in their service
delivery. The consolidation of the Lead and Deadwood school districts
offers a prime example of such adjustments.
While some efficiencies were achieved, the continuing fiscal
pressures have resulted in some reductions in service levels. For
example, the budget for street maintenance in Deadwood was described as
being just adequate for maintenace, but with little allowance for
undertaking improvements. Similarly, the Deadwood Police Chief had
requested sufficient budget in 1985 to hire an additional officer to
increase the department's total staff to seven. Instead, his budget
was cut and his staff reduced to a total of five.
The continuing pressures on local government budgets is perhaps
no where more apparent than in the administrative facilities. Lead's
City Hall is only about 50 percent utilized and is in good structural
repair, although substantial mechanical improvements are needed.
Deadwood1s administrative functions are housed in the old railroad
depot which has been converted. The City's fire and police departments
are also housed in the same facility. The original County building has
been condemned as unsafe, so some county functions have relocated to
the basement of the county law enforcement center, while others have
temporarily moved to leased space in the downtown retail/commercial
district. Both Lawrence County and the City of Deadwood are pursuing
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plans to acquire and/or build new administrative facilities, but no
firm plans currently exist (C. Koerner, Lawrence County Planner,
personal communication 1986; J. Brodsky, City of Deadwood, personal
communication, 1986).
Fiscal Resources
Assessed Valuation
Assessed valuation of real property and improvements such as homes
and office buildings is a key component of local fiscal resources. It
is the basis on which local property taxes are levied by local govern-
ments. In the area of influence, property taxes are the primary
sources of revenue. Assessed valuation for Lawrence County, the City
of Lead, and City of Deadwood is shown for 1984 through 1986 in Table
36 below.
TABLE 36
TOTAL ASSESSED VALUATION IN LAWRENCE COUNTY,
LEAD, AND DEADWOOD, 1984 to 1986
1984 1985 1986
Amount Amount Amount
Lawrence County $304,844,984 $313,043,689 $334,442,498
City of Lead 72,233,645 71,953,025 73,014,130
City of Deadwood 23,927,799 24,138,004 25,016,350
Note: Assessed valuation as determined by the County Board.
Source: Lawrence County, 1986b.
Lawrence County. In fiscal year 1986, assessed valuation on all
vacant and developed land in Lawrence County totalled $334,442,398.
The large majority, or 92 percent of this valuation, derived from
non-agricultural property, most of which had improvements in place.
Approximately 57 percent of total valuation was from such properties
located within city limits, and 35 percent from improved properties
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located outside corporate limits. In addition, eight percent of total
valuation was derived from properties zoned agricultural, almost all of
which are located in unincorporated portions of the county.
Between 1984 and 1986 there have been some changes in the relative
shares of assessed valuation in Lawrence County from properties zoned
agricultural or non-agricultural and located within or without corpor-
ate limits. Most notable has been the increase of nearly four percent
in the relative importance of non-agricultural properties outside
corporate limits and a corresponding decrease in the share of valuation
from similar properties in incorporated locations.
City of Lead. Total 1986 valuation of property in the City of
Lead equalled over $73 million. This accounted for nearly 22 percent
of the total county-wide property valuation. The share of county-wide
valuation within Lead's corporate boundaries has declined slightly over
the last few years, down from almost 24 percent in 1984, corresponding
to the countywide decline in the share of valuation from within city
limits.
City of Deadwood. As with Lead, the share of total county-wide
property valuation located within Deadwood city limits has declined
slightly over the 1984 to 1986 period. Total valuation in the city in
1986 was over $25 million, up from nearly $24 million in 1984. As a
share of the county-wide total however, assessed valuation in Deadwood
has declined slightly from 7.8 percent to 7.5 percent.
Revenues
Lawrence County. Because South Dakota counties do not collect
sales taxes, property taxes are the main source of revenue. In
Lawrence County, property taxes account for approximately 60 percent of
the projected 1986 revenue base. Other sources of revenue derive
primarily from intergovernmental transfers, as well as from fees for
licenses and permits, and interest earnings.
Total taxable property valuation in Lawrence County is derived as
a 45 percent share of total assessed valuation. Tax levies for 1985,
payable in 1986, were assessed by five entities: school, county, fire
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protection, city or township, and sanitation. The total mill levy for
the county tax alone was 16.43 mills ($16.43 per $1000 of taxable
value), of which 13.23 mills is to be used for general county opera-
tions. The additional levies were for snow removal, highways and
bridges, and the public library.
Between 1984 and 1985, the total county levy was increased sub-
stantially, by nearly twelve percent. During the previous year, the
county levy had been raised by a much lower margin of under six per-
cent. Approximately one-third of the 1984-85 increase was for highway
and bridge reserve; the remainder went to the general county fund.
City of Lead. Current revenues for the City of Lead in 1986
totalled slightly more than $2 million. Well over half of these
revenues, or nearly $1.3 million, have been applied to the city's
general fund. Most of the general fund revenues are derived from
taxes, including both property and sales taxes. In 1986, almost
$650,000 accrued to the city in property taxes, accounting for half of
the total general fund, and close to $400,000, or about 31 percent of
the total general fund revenues were derived from sales taxes. Over
half of this sales tax, however, resulted specifically from back taxes
paid by the Homestake Mining Company. Typically, then, Lead's sales
tax revenues are considerably lower and account for a somewhat smaller
share of total tax collections.
Several other sources comprise the remaining share of the city's
general fund. Intergovernmental revenues, primarily personal property
replacement tax received from the State, and the county bridge fund
transfer provide the most revenue. Other revenues are derived from
licenses and permits, charges for goods and services, fines and for-
feits, and miscellaneous sources, including lease revenues, interest on
investments, and reimbursements. Together, these sources provided an
additional $210,000 to Lead's general fund In 1986.
In addition to its general fund, the City of Lead maintains
several other funds under which current revenues are accounted. An
amount of $650,000 was earmarked for capital improvements in 1986;
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these revenues were derived primarily from the issuance of bonds and
insurance proceeds. In addition, the library fund showed a balance of
over $38,000 that year and the sewer and rehab funds were at $40,000
and $5,000, respectively. Revenues for these three funds came pri-
marily from the city or special district mill levies.
City of Deadwood. In 1986, Deadwood's general fund totalled
slightly more than $800,000. Approximately 41 percent, or $310,000 of
these revenues were generated from property taxes and 36 percent from
sales taxes. The remaining 23 percent of general fund revenues were
derived from a combination of license and other fees, permits,
interest, etc. The relative importance of the two taxes and other
revenue sources to total general revenues differs notably in Deadwood
compared to Lead, where sales tax accounts for a smaller share of
general revenues. This difference reflects the difference in the
economic base of the two communities, whereby Lead is more heavily
focused on mining while Deadwood relies on tourism.
The City of Deadwood applies revenues to a number of funds in
addition to the general fund, reaching a total of approximately $1.4
million in unencumbered funds in 1986. These additional revenue
sources include: parking meter; revenue sharing; water project; water
enterprise fund; library; sanitation enterprise fund; and Mt. Moriah
restoration.
Revenue sources for Deadwood, along with Lead
and Lawrence County are indicated in Table 37.
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TABLE 37
REVENUE SOURCES FOR LAWRENCE COUNTY,
LEAD, AND DEADWOOD, 1986
Revenues Category
Total
General Fund
Property Tax
Sales Tax
Inter-Governmental
Permits
Licenses, Service
Charges, Fines
Other
Revenue Sharing
Library
Other
Lawrence
County
$5,498,190
64.2
37.0
2.2
25.0
2.8
33.0
Lead
$2,015,750
Percent of Total
63.6
31.2
19.8
5.7
2.3
4.6
1.8
26.6
Deadwood
$1,704,444
47.3
29.1
18.2
2.3
2.3
48.1
Source: Lawrence County 1986a; City of Lead, 1986; City of
Deadwood, 1986.
Expenditures
The pattern of appropriations of general funds by the county and
the cities of Lead and Deadwood are shown in Table 38.
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TABLE 38
BUDGET APPROPRIATIONS FOR LAWRENCE COUNTY
LEAD, AND DEADWOOD, 1986
Lawrence
Expenditure Category County Lead Deadwood
Total $5,498,190 $1,282,607 $1,704,444
Percent of the Total
General Government 25.2 22.0 6.0
Public Safety 14.8 23.8 14.3 ,
Public Works 25.2 49.7 50.2a/
Health 5.3 1.5
Culture and Recreation — 3.0 13.4
Other 29.5 — 16.1
a/
Appears as "Highways and Streets" in Deadwood Budget.
Sources: Lawrence County, 1986a; City of Lead, 1986; City of
Deadwood, 1986.
Lawrence County. As shown in Table 38, the county's budget
appropriations for 1986 totalled nearly $5.5 million. General govern-
ment and public works account for the highest appropriations among the
itemized categories. Nearly 30 percent of total appropriations are in
the "other" category, however. These funds are primarily for planned
capital outlays, including possible restoration of the historic opera-
house which suffered severe fire damage, and participation in infra-
structure improvement costs to support a new residential and commercial
subdivision.
The 1986 budget appropriations by the county mark an increase of
about 36 percent from the previous fiscal year; total expenditures
Increased between 1984 and 1985, as well, but by a smaller margin of
slightly more than 10 percent. Over this period, the share of funds
appropriated for general government and public works decreased as the
share earmarked for capital outlays increased tremendously.
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City of Lead. In Lead, the greatest share of funds appropriated
to any single budget Item went to public works, totalling nearly half
of the general fund total appropriations in 1986. Over one-third of
the public works budget is for streets, including some minor capital
improvements and general maintenance. An additional large public works
expenditure goes for solid waste pickup and disposal, which is provided
on a contract basis by a private firm.
Public safety also received a large share of general revenue funds
in Lead for fiscal year 1986 that was greater than in either the county
or neighboring Deadwood. The share of appropriations going to general
government in Lead accounted for much of the remaining funds; at 22
percent of the total fund, Lead's relative appropriation for general
government was close to the county's.
In addition to the general fund appropriations, revenues for the
city's other funds were apportioned fully. Most of the $650,000 for
capital improvements was earmarked for construction of a proposed
recreation center and $150,000 of the total will go to fund a develop-
ment corporation which will be involved with actual residential
development and provide assistance on commercial and motel development.
City of Deadwood. As in Lead, public works received the largest
share of Deadwood's total budget, accounting for half of all general
funds. General government is funded at a much lower level in Deadwood
than in either Lead or the county. However, culture and recreation
accounts for a much greater share of Deadwood's budget. The "other"
category, receiving about 16 percent of Deadwood's general funds,
includes in this case enterprise funds such as water and sanitation,
and debt service.
Recreation Resources
In addition to mining, tourism and outdoor recreation play key
roles in the local economic base and in the lifestyles of local resi-
dents. The Black Hills abound with a variety of public and private
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recreation opportunities. The majority of these opportunities are
supported by the public lands of the Black Hills National Forest
administered by the U.S. Forest Service.
In the immediate Lead/Deadwood area, the primary developed recrea-
tion sites are the Deer Mountain and Terry Peak ski areas. The two ski
areas are located on adjacent peaks about 5 kilometers (3 miles)
southwest of Lead and are the only downhill ski areas within a 150-mile
radius of Lead/Deadwood. The existing Wharf Resources Annie Creek and
Foley Ridge projects are located 1.5 to 2.5 kilometers (1 to 1.5 miles)
west and northwest of Terry Peak and major areas of exploration sur-
round both areas on three sides. Some leased public land is involved
in the Terry Peak operation, while the majority of the property and all
of the Deer Mountain ski area is in private ownership.
Typically each of the ski areas sells between 40,000 and 60,000
lift tickets in a season, serving a regional market. Approximately 50
percent of the total skiers are local residents, with the remaining
visitors coming from the rest of South Dakota, Wyoming, Montana, and
North Dakota (J. Mattson, Deer Mountain Ski Area, personal communica-
tion, 1986; G. Akrop, Terry Peak Ski Area, personal communication,
1986).
The sole remaining public developed recreation site in the immedi-
ate vicinity is the Hanna Campground, located on Spearfish Creek, about
3 kilometers (2 miles) off of U.S. Highway 85 south of Cheyenne Cross-
ing. Access is via Forest Service Road 222.
Numerous other Forest Service developed recreation sites exist in
the forest, but are more distant from Lead-Deadwood. Two campgrounds
are located on Schoolhouse Gulch, off of Spearfish Creek, about 16 to
18 miles from Lead via U.S. Highway 85 and U.S. Highway 14 ALT; three
large lake and reservoir-based recreation areas are located in Pennlng-
ton County 40 to 48 kilometers (25 to 30 miles) south of Lead-Deadwood;
and several developed campgrounds and picnic areas are located around
the community of Nemo in the southeast corner of the county (U.S.
Forest Service, 1980; 1986b).
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A substantial amount of dispersed recreation is also supported by
the public lands. Deer and game bird hunting, fishing, hiking, camping
and four-wheel driving are all popular activities. According to local
officials, all of the areas where recent gold exploration is occurring
and where potential operations could be located are excellent hunting
areas. Spearfish Creek, rated a blue ribbon trout stream in some
areas, offers the best fishing, with fishing quality characterized as
good on Whitewood, Deadwood, Whitetail and Strawberry creeks following
a recent cleanup effort by the Homestake Mining Company. Fishing
quality on other streams varies from fair to poor depending on the
volume of flows and water quality. Stocking programs are relied on to
maintain fish populations in all of the streams (C. Webster, Lawrence
County Conservation Officer, 1986). Two elk habitat areas exist in the
region—one each located southeast and southwest of the Lead/Deadwood
area. Because of limited herd sizes and harvesting quotas, only a few
hunting licenses are issued each year. Demand for the licenses is
heavy, so licenses are issued using a lottery. No licenses are cur-
rently issued for hunting elk in the habitat area encompassing the Two
Bit Creek study area (D. Linde, South Dakota Department of Game, Fish,
and Parks, personal communication, 1986).
As mentioned previously, the region is becoming increasingly well
known for its snowmobiling opportunities. Nearly one-fourth of the
state's developed snowmobile trail system exists in Lawrence County and
one-half of the total system exists in the Black Hills (see Figure 18).
An annual event in the area which brings snowmobile manufacturers and
magazine publishers together to test the new products is attributed
with spurring an increase in snowraobiling interest in the area. Most
of the trail system is located to the west and south of the general
area of mining interest.
Snowmobiling and cross-country skiing on a more dispersed and
unorganized basis occurs throughout the area on the many logging roads
developed to support the local timber industry (P. Mock, Black Hills
National Forest, personal communication, 1986).
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Lifestyles and Attitudes
A common link among most residents and visitors to the local area
of influence is the area's natural resource base. Whether involved in
mining or timber harvesting, a permanent resident, an owner of a
vacation home in the region, or a tourist, it is the geological, bio-
logical, and scenic resources which are primarily responsible for human
presence in the region.
With respect to the current level and pattern of development, gold
mining is the key influence. The first publicized discovery of gold in
the area occurred in 1874 and the Horaestake Mining Company became a
primary economic force in 1876. For the past 110 years, the Homestake
Mining Company and its operations have not only been a stabilizing
force, but also the predominant economic force driving the region's
entire economic structure. The mine created employment opportunities
which attracted new workers and households to the area. The residents
in turn generated demands for food, housing and other household com-
modities. Initially, these items were transported into the region
because they were not available locally. Over time, these needs
spawned the local agriculture and service and trade base. The mining
activity itself, along with the indirect household needs provided a
catalyst for the local timber industry to become established and
supported the development of the railroad into the area. At the same
time, the company found itself in the position of assuming many of the
functions of a local government and non-mining private enterprise in
the development of a residential community, retail base and public
infrastructure.
This historical relationship has carried over to present times.
According to several local officials, it is the perspective of many
residents that mining continues to be the economic mainstay in the
local economy. Tourism, tlrabering/wood-processing, recreation and
manufacturing are beneficial and help in achieving a semblance of
diversification, especially in other areas of the county-, but mining is
the dominant activity.
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Furthermore, for years the Horaestake Mining Company has been
perceived as a benevolent, paternal entity, which provided secure
employment and demonstrated real concern for its employees, families
and their communities. In return, it expected and fostered a deep
sense of loyalty. Thus, when faced with the prospects of additional
mining, there is a strong sense of positive and beneficial impacts,
that is, a source of economic livelihood. This may be especially true
since the level of employment at Homestake has been declining consis-
tently over the past four to five years.
Against this all-pervasive background, there are several other
perspectives and lifestyles that must be considered. One is that of
the temporary residents, that is, summer homeowners in the area and the
many vacationers to the region. These persons are attracted by the
area's scenic beauty, recreational opportunities and its historic and
current links to mining. Although mining, the development of trans-
portation and community infrastructure, and in many instances, even the
land in private ownership on which the summer homes are built, are to
some extent responsible for their attraction to the area, their pers-
pective is focused on leisure pursuits, not economic livelihood. They
are therefore, typically opposed to actions which might directly or
indirectly adversely impact their enjoyment of the area. Such impacts
could include additional noise or traffic in the vicinity of resi-
dences, possible loss of the dwelling itself in instances where the
structure is built on leased land or on land where another party owns
the mineral rights, or degradation of visual and aesthetic resources
resulting from the operation's activities. The latter issue seems to
be related primarily to the fact that the heap leach process is pri-
marily surface-oriented compared with the underground operations more
commonly associated with raining. Obviously the Horaestake open cut
operation in Lead is not underground, but neither does it seem to evoke
the same opposition from the temporary residents. This dichotomy of
economic livelihood versus leisure pursuits defines one of the primary
sources of potential lifestyle conflicts associated with mining.
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Somewhat closely aligned with the summer homeowners and tourists
in their opposition to mining, but for different reasons, are interest
groups representing recreation and environmental concerns. The general
perspective of these interest groups is that extractive industries such
as mining result in degradation of the environment, interfere with
other, non-consumptive and non-extractive uses in the area and should,
therefore, be restricted or prohibited. Although these interests are
recognized among local residents, no organized group or individual was
identified during numerous conversations with local officials as being
especially critical or active in their opposition to further heap leach
mining. Representatives of both the raining industry and local govern-
ment tend to share the perspective that while the existing natural
environment and other non-raining uses of the environment are important,
mining and other uses can coexist, and raining can and should occur.
The Lawrence County Zoning and Subdivision Regulations (Lawrence
County, 1986c) allows for mining and related activities within all zone
districts as a use by right. The zoning ordinance requires a special
use permit for purposes of insuring that adjacent land uses are proper-
ly buffered and protected, and to insure proper reclamation of the site
when mining ceases.
The goals and policies statement of the Comprehensive Plan (Brady
and Chichester, 1969) further reinforces these two points. The extrac-
tive industry policies are:
In order to insure continued development of natural
resources prior to development of the land for other
purposes, extractive industries should be allowed to
locate in areas known to have deposits of minerals and
materials.
After the industry has depleted the raw material, or
has been abandoned, the land should be reconditioned in
such a fashion that it can be used by some other type
of land use.
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However, in an effort to address possible conflicts, the county
uses a conditional use permit system, not to deny mining companies the
right to extract minerals, but to reasonably condition the operation,
when deemed necessary, for the protection of public health, safety and
welfare.
Another common perception regarding heap leach raining identified
during discussions with local officials and residents, was that much of
the earlier and to some extent the continuing consensus was based on a
combination of uncertainty, ignorance and fear along with several
events/actions of some of the mining operations.
Several comments were received indicating that, on the one hand,
opposition was raised because residents just were not sure of the
location, extent and timing of exploration or proposed operations. On
the other hand, the lack of this information effectively limited the
voicing of specific concerns, for example, the potential for adverse
impacts on either of the developed downhill ski areas. The managers of
these facilities were concerned about the potential for impacts, but
could not elaborate specifically because they did not have sufficient
information regarding these operations.
Ignorance and fear were also cited as factors underlying the
expressed concerns, especially with regard to the cyanide mineral
removal process and the design and operation of the heap leach facility
itself. Although the use of cyanide solutions is well-established and
apparently is also used by Homestake in its processing, it is unfami-
liar to most individuals. Furthermore, there has been an overall
heightened awareness of hazardous materials and environmental concerns
in recent years. When faced with the prospect of an industrial opera-
tion using the process, concerns and opposition were voiced.
Finally, the actions of several mining companies contributed to
some sense of mistrust and concern. First, the mining companies tend
to be less than open with respect to their exploration activities and
plans for operations. This behavior is frequently necessary to protect
corporate interests. Secondly; several mining companies were faulted
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for their dealings with local residents and property owners. For
example, one company exercised its rights to vacate current residents
from its property with 30-to-50 day notice under the terras of a lease
agreement between the parties. While the company was within its rights
to do so, the manner in which it was done and the fact that the company
was not in the position of imminently undertaking operations, irritated
and angered some residents; it had not been done with the same sensi-
tivity, forethought and concern as Homestake would have used. Finally,
there were a few "incidents" in the initial phasing of the Wharf
Resources Annie Creek operation. Apparently, one of these involved an
overflow of the primary containment pond following a heavy early spring
blizzard. None of the individuals contacted cited any adverse impacts
of the accident, but it nevertheless fostered mistrust and concern.
By almost unanimous consent, an increased level of understanding
and awareness regarding the process and heap leach operations, as well
as efforts by several mining companies to improve their operations and
work within the community have diminished the level of concern and
conflict. However, the uncertainties stemming from a lack of specific
information regarding anticipated development and community sensitivity
to the manner in which mining affairs are handled continues (C.
Koerner, Lawrence County Planner, personal communication, 1986; H. Lux,
City of Lead, personal communication, 1986; J. Todd, Trojan area
resident, personal communication, 1986; H. Scholz, Wharf Resources
Ltd., personal communication, 1986).
A positive step to address at least some of the residual concerns
is currently underway at the local level. The Lawrence County Task
Force on Mining has been established. Comprised of members of local
government, civic organizations, the mining industry and property
owners, the Task Force is considering ways to minimize further con-
flicts. The primary results of the Task Force are expected to be the
requirement that a comprehensive socioeconomic impact statement be
prepared and approved prior to the issuance of a conditional use permit
for an extractive industry and the establishment of a buffer zone
surrounding areas of active operations separating the operations from
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adjoining land uses. When finalized, these stipulations will be
incorporated into the Lawrence County Zoning and Subdivision Regula-
tions.
Descriptions of Alternative Mining Sites
Active exploration and feasibility assessments for numerous gold
heap leach facilities are currently occurring with respect to locations
to the west, southwest and east of the Lead-Deadwood area. Although
the general socioeconomic environment is the same for each of these
areas there are some variations in site-specific characteristics. A
brief discussion of each of these areas is provided below.
Raspberry Gulch
The Raspberry Gulch site is located approximately 8 kilometers (5
miles) southwest of Lead. The area is located north of the confuence
of the east and west forks of Spearfish Creek. Land in the immediate
and surrounding areas is predominately under Federal government owner-
ship and Is managed by the U.S. Forest Service.
Several areas of permanent and seasonal occupancy residential
development exist in the vicinity of Raspberry Gulch. Dutch Flats is
located just north of the site. It contains more than 20 homes and an
estimated 50 additional lots. Several clusters of homes, mostly for
seasonal occupancy, are located near Cheyenne Crossing and along
Spearfish Creek, just to the southwest of the site. Finally, two
subdivisions of permanent and seasonal homes are located approximately
2.4 kilometers (1.5 miles) east-southeast of the site along U.S.
Highway 85.
Recreation occurring in the vicinity of Raspberry Gulch includes
the region's only two downhill ski areas. Dispersed recreation in the
area includes cross-country skiing, hunting and fishing. Spearfish
Creek is rated as the best stream fishing in the region.
Yellow Creek
The Yellow Creek site is located due south of Lead in the Yellow
Creek drainage. Land ownership is a combination of private and Federal
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government with the public lands under the management of the Bureau of
Land Management. Adjoining land uses in the general vicinity include
limited residential development and several public and private dump
sites. Therefore, the area already receives heavy truck traffic. Some
additional residential development exists about 1.6 to 2.4 kilometers
(1 to 1.5 miles) to the east and west of the site along U.S. Highway 85
and U.S. Highway 385. A ridge line separates these areas from direct
visual contact with the site. According to local sources, only limited
dispersed recreation occurs In the area.
Two Bit Creek
Located approximately three miles east of Lead-Deadwood, the Two
Bit Creek site involves an area of private and federal government
lands. The Federal lands are administered by the U.S. Forest Service.
Access to the area is provided by U.S. Highway 14 ALT east from Dead-
wood, then south on a Lawrence County road along the Peedee Gulch and
finally via a U.S. Forest Service road. Several clusters of permanent
and seasonal residential home developments exist along the Lawrence
County road, some within a mile of the mining area. As in Yellow Creek
only limited dispersed recreation occurs in the area, primarily hiking,
hunting and 4-wheel driving.
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CHAPTER 4
POTENTIAL IMPACTS AND CONCERNS
HYPOTHETICAL CYANIDE HEAP LEACH FACILITY
The cyanide heap leach facility described below is a hypothetical
raining operation that Is a composite of several operating mines. It is
not Intended to portray a specific existing mine. The facility is
shown in a schematic diagram in Figure 19. Each of the components is
discussed in more detail in later sections. The entire hypothetical
heap leach facility disturbs approximately 400 hectares (1,000 acres)
and employs about 100 people throughout its 10-year life.
To assess potential impacts, this hypothetical facility Is Imposed
onto three actual locations in the northern Black Hills (refer to
Figure 2). One site is located 8 kilometers (5 miles) southwest of
Lead in the Spearfish Creek drainage near Dutch Flats, along Raspberry
Gulch. The second site is located 3 kilometers (2 miles) southeast of
Lead in the Whitewood Creek drainage along Yellow Creek. The third
site is located near Dome Mountain and Two Bit Creek about 5 kilometers
(3 miles) east of Deadwood in the Bear Butte Creek drainage. All three
sites are near ore bodies in the headwaters of their respective drain-
ages.
It Is assumed that the hypothetical mine is in compliance with all
requirements of the State of South Dakota and that all necessary
permits have been obtained. It is further assumed that a monitoring
program was set up and site-specific baseline data were collected In
conjunction with the permitting requirements for the hypothetical mine.
Water consumption is minimal since the process recycles the working
solution. The small amount of water needed for process makeup (loss of
5 to 10 percent from evaporation) and domestic consumption is obtained
from wells. The cyanide process is a closed system and will not
discharge fluids to surface or ground waters during normal operating
procedures.
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FIGURE 19
SCHEMATIC DIAGRAM OF THE HYPOTHETICAL
MODEL HEAP LEACH FACILITY
MINE PIT
200 HECTARES
WASTE
ROCK
DUMP
120 HECTARES
\-
CRUSHING
AREA
2 HECTARES
LEACH PAD
60 HECTARES
^
1- «,
,^_
« 1
•jr UJ 1
Z
0
H 05
< u
N 5
< B
< iu
QC x
1- t
:3
UJ
z
;ssx
JT >
0.5
HECTARES
*-
PREGNANT
POND
4 HECTARES
1 BARREN
or* kin
11
2 HECTARES
OVERFLOW
POND
2 HECTARES
ROADS
PIPELINES
171
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The mine Is described below in sufficient detail to enable an
assessment of potential impacts. However, it has not been designed for
specific topographical variations or variations In ore bodies which may
be encountered at the three different sites. Although this mine design
is typical of mines that might be placed in the area, and facilitates
the discussion of Impacts, other designs may be more appropriate in
actual circumstances.
Mine Pit Area
Ore Is removed by the open pit method. Prior to excavation,
vegetation is removed and the topsoil stockpiled. Daily blasting with
0.3 kilograms of ANFO per metric ton (0.5 pounds of ANFO per short ton)
of broken rock in 8-centimeter (3-inch) drill holes loosens the rock.
The material is then removed from the pit by hydraulic shovels, rubber-
tired front-end loaders, and 35-metrie-ton (40-short-ton) capacity
trucks. Pit construction consists of 6- to 7.5-meter (20- to 25-foot)
benches and a 45-degree pit wall. The pit will not be at a depth that
would Intercept ground water. Surface runoff resulting from precipi-
tation is collected by maintaining inward-sloping benches. Collection
sumps on these benches hold excess water for use in sprinkling roads
and dumps for dust control. Sedimentation from exposed mine areas and
the waste dump fill is largely controlled by temporary sediment collec-
tion ponds. Diversion ditches were constructed to divert runoff around
the mine pit and back into the natural drainages downstream from the
disturbed area.
During reclamation, benches will be revegetated. The pit will not
be backfilled because a change in metal prices or technology may make
the processing of remaining ore economically viable.
Approximately 13,500 metric tons (15,000 short tons) of waste rock
and ore are mined daily. Of this, 4,500 metric tons (5,000 short tons)
are ore and 9,000 metric tons (10,000 short tons) are waste rock. The
mine pit will disturb about 200 hectares (500 acres).
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Waste Rock Disposal Area
Waste rock from the mine pit is hauled by 35-metrie-ton (40-
short-ton) capacity haul trucks to a nearby disposal area which was
prepared by removing vegetation and stockpiling the topsoil. The waste
disposal site will cover approximately 120 hectares (300 acres) and be
about 15 meters (50 feet) high. During reclamation, the mine dump will
be graded, topsoiled, and revegetated.
Roads
Roads in the facility are single-lane, 9-raeter-wide (30-foot-wide)
dirt roads. Water is directed to drainage- ditches and culverts.
Settling sumps are provided where necessary to settle suspended solids.
Cut and fill slopes will be revegetated as needed early in the project.
Where possible, roads are located away from streams to provide adequate
buffer areas. Dust is controlled by watering or surfacing with treated
process waste or waste rock. Reclamation of abandoned haul roads and
access roads will involve ripping hard surfaces as necessary, recon-
touring, topsoiling, and reseeding.
Crushing Facility
Ore is hauled by truck to the crushing facility where it is
stockpiled. It is later transferred to a primary crusher by a dozer.
The crushed ore is transferred to a secondary crusher where it is
ground to less than 3.18 centimeters (1.25 inches). The crushed ore is
stockpiled for subsequent hauling to the leach area. The pieces of
crushing equipment, which include a vibrating grizzly jaw crusher, a
cone crusher, rolls, and vibrating screens, are portable, trailer-
mounted units. For pH control in the leaching process, 0.75 to 1.0
kilograms of lime per metric ton of ore (1.5 to 2.0 pounds of lime per
short ton) are added in the crushing circuit. The crushed ore is
transported in trucks to the leaching pad. Dust suppression is accom-
plished by the use of water spray and/or dust collection devices.
Approximately 2 hectares (5 acres) are disturbed by this facility.
They will be topsoiled and revegetated during reclamation.
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Heap Leach and Process Area
The heap leach and process area consist of a one-time-use heap pad
system, pregnant pond, barren pond, neutralization pond, overflow/fresh
water pond, and recovery plant as shown in the schematic drawing,
Figure 19. The total disturbed acreage will be 80 hectares (200
acres). Of this, the heap leach area will comprise 60 hectares (150
acres) and the process area will comprise 20 hectares (50 acres). The
heap leach operation will be a closed system with no discharge to
surface or ground waters. Water balance of the heap and ponds have
been designed to meet the State of South Dakota requirements for
probable maximum precipitation (PMP). In the study area the PMP is
82.6 millimeters (3.25 inches) In 1 hour and 480 millimeters (19
inches) in 6 hours. The components of the heap leach and process area
are described in more detail below. The design detail for the pad
liner and pond linings Is generally that preferred by the State of
South Dakota. Other designs may be equally suitable.
Heap Leach Facilities
The leach heap area contains the pad and leak detection system,
ore heaps, sprinkler system, heap drainage collection system, and
stream diversion ditches. The soil below the heap has been tested and
found suitable for heap stability. Before pad construction was Initi-
ated, vegetation was cleared from the site. The topso11 was removed
and hauled to the topsoil stockpile. The pad base was graded and
sloped to permit containment as well as drainage of the leached solu-
tion to the appropriate collection areas. Natural drainage was divert-
ed away from the heap and pond area into a diversion ditch. The heap
pad system consists of 20 centimeters (8 inches) of clay covered by
30-mil PVC, which is in turn covered by geotextile fabric. A French
drain system has been constructed beneath the clay to provide leak
detection. This leak detection system drains into the pregnant pond.
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After the ore Is crushed, it Is loaded Into haul trucks and end
dumped as lifts on the pad. A front-end loader spreads the ore into 3-
to 4.5-meter high (10- to 15-foot-high) lifts. Each lift is ripped by
a dozer to improve infiltration for the leach solution. Subsequent
lifts are added and leached. The height of the ore heaps is from 6 to
12 meters (20 to 40 feet).
The four ponds are located near the ore heap pad as shown in
Figure 19. The soil beneath the ponds has been tested and found
suitable for stability of the ponds. Construction of the ponds
occurred after vegetation had been removed and topsoil had been hauled
to the topsoil stockpile. The pond liner consists of 30 centimeters
(12 inches) of clay, 30-mil PVC, 30 centimeters (12 inches) of sand,
geotextile fabric, and 30-mil hypalon. The leak detection system
consists of the sand layer which drains into a channel. A standpipe is
connected to the channel so that samples may be taken.
The recovery plant contains the facilities to remove the gold and
silver from the pregnant solution. The soil has been tested and found
to be adequate for foundation stability. Vegetation and topsoil were
removed from the foundation area and the topsoil stockpiled. The
building contains carbon columns, a stripping solution tank, and a
secured area for the production of dore (gold and silver bars).
A 2.4-meter-high (8-foot-high) mesh wire fence encloses the entire
area containing the heap, ponds, and recovery plant. Signs are posted
along the fence warning that cyanide is In use and that no trespassing
is allowed. Strips of flagging are strung above the barren and preg-
nant ponds to deter birds from landing in the ponds. The lined collec-
tion ditch downgradient from the heap is partially filled with coarse
rock to prevent birds from using the ditch.
Leaching Process
The cyanide solution for the leaching process is made by first
adding caustic soda (sodium hydroxide) and then adding sodium cyanide.
Free and total cyanide concentrations are approximately 225 mg/1 and
250 mg/1, respectively. The pH is 10.5. The cyanide solution is
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pumped from the barren pond to the top of the heap through PVC pipe.
The pipes are arranged so that accidental leakage can be readily
collected and contained. A sprinkler system is placed on the heap in a
6- by 12-meter (20- by 40-foot) grid pattern to provide overlapping
coverage of the surface. The cyanide solution is sprayed through
wobbler-type sprinklers at a rate of 12 liters per square meter per
hour (0.3 gallons per square foot per hour). The cyanide solution
leaches the precious metals from the ore and collects In a ditch
located downgradient from the heap, which drains by gravity to the
pregnant pond.
The pregnant solution is pumped to the recovery plant where gold
and silver are extracted. The concentration of metals In the pregnant
solution are approximately 30 mg/1 Iron, 5 mg/1 arsenic, 1 mg/1 cobalt,
1 mg/1 gold, and 0.005 mg/1 silver. The pregnant solution is fed
through a series of columns containing granular activated carbon. As
the solution flows through the carbon, gold and sliver are adsorbed
onto the carbon surface. When the carbon is loaded to capacity with
metals, it is removed and stripped in the pressure strip tank with an
alcohol caustic cyanide solution. The gold and silver is then removed
from the stripping solution by electrowinning. The stripped carbon is
regenerated by heating in a kiln and washing with nitric acid.
Cyanide at a rate of 0.3 kilograms per metric ton (0.5 pounds per
short ton) of solution must be added to the barren solution at the
outflow of the recovery plant. Adjustments to the pH of the process
solution can also be made before the process circuit is repeated.
Closure Plan
Closure will consist of the neutralization of the spent ore heap,
disposal of the process solution and neutralization solution, and
decommissioning and reclamation of all facilities. The neutralization
process consists of rinsing the spent ore with a hypochlorite solution
until the spent rinse solution contains less than 0.75 mg/1 of total
cyanide. This method, the alkaline chlorination process, will be used
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to oxidize free cyanide and cyanide from weakly bonded cyanide com-
plexes. The hypochlorite solution will contain chlorine at a
concentration of approximately 1,000 mg/1 free chlorine and have a pH
between 10 and 11. The solution will be sprayed on the heap using the
same sprinkler system used for the leaching operation. The rinsing
solution will collect downgradient from the heap and will be pumped to
the neutralization pond, where it will be recycled through the heap.
The spent rinse solution from neutralization and the process solution
will be disposed by evaporation in the ponds. Any residue remaining
from evaporation will be tested for metals and cyanide and disposed of
properly.
After the neutralization is complete, the facilities will be dis-
mantled, sold as scrap, or buried onsite. Equipment which may contain
cyanide or other hazardous materials will be thoroughly cleaned prior
to removal from the project site. After the recovery plant is decom-
missioned, the concrete foundation will be broken up and buried. The
linings from the ponds will be dug up and buried. The pond area and
recovery plant area will be restored to their natural contours. Top-
soil from the stockpile will be applied and the area will be reseeded.
The neutralized heap pile slopes will be contoured to the ground
surface. The pad liner will be punctured to allow natural drainage.
Topsoil will be spread over the pile and the area will be reseeded.
ACCIDENTAL RELEASE OF CYANIDE SOLUTION
A properly designed and operated cyanide leaching project would
not be a greater threat to environmental quality than any other indus-
trial development of a similar scale not involving the use of cyanide
since cyanide solutions are not discharged under normal operations.
However, for purposes of evaluating impacts, two types of accidental
releases of cyanide process solution, which would be highly unlikely at
a well designed and operated mining operation, will be analyzed for
potential effects. The two types of accidental releases include:
Overflow of the pregnant solution pond; and
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Release of cyanide solution from a leak in the pregnant pond
liner.
The discussion will evaluate factors in the environment which would
attenuate cyanide and metals toxicity, determine approximate concentra-
tions of toxic substances at selected points of contact, and define
impacts of the spill on natural resources. This analysis is not
concerned with the likelihood of an accidental release or the exact
mechanics of a pond overflow, leak, or backup system failure.
Several chemical and biological processes, as shown in Figure 20,
have the potential to attenuate cyanide when it is released to the
environment. These processes which are discussed in detail in Appendix
B, result either in degrading or transforming free cyanide into a less
toxic species.
Pond Overflow
The overflow of the pregnant pond has occurred during the spring-
time due to a combination of snowraelt and a heavy thunderstorm. The
concentration of cyanide in the pregnant pond has been reduced by
dilution to 200 mg/1 free cyanide and 225 mg/1 total cyanide. The
concentrations of metals are approximately 25 mg/1 iron, 4 mg/1 arse-
nic, 1 mg/1 cobalt, 1 mg/1 gold, and 0.004 mg/1 silver. Actual spills
at cyanide heap leach operations have ranged from very small to 23,000
cubic meters (6 million gallons) (refer to Appendix D). For this case,
100 cubic meters (27,000 gallons) were released from the pond at a rate
of 2.8 liters per second (45 gallons per minute) over a 10-hour period.
After flowing across the saturated ground which is partially snow
covered for approximately 0.8 kilometer (0.5 mile), the spill enters
surface water.
The effect of a pregnant pond overflow on surface water depends on
the amount of dilution and attenuation. These are functions of the
overland distance traveled, the distance to a major drainage, and the
flow in the drainage. The attenuation of cyanide in this example spill
is based on an actual spill where cyanide solution with 200 mg/1
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FIGURE 2O
SUMMARY OF POTENTIAL DEGRADATION AND TRANSFORMATION
PROCCESES FOR CYANIDE AT A TYPICAL HEAP LEACH MINING OPERATION
EVAPORATION
PRECIPITATION
STREAM OVERLAND SPILL POTENTIAL
CYANIDE
LEACH SOLUTION
! ~~
HEAP
Degradation and Transformation
Processes For Cyanide '
Surface Processes:
Vol.it I I 1 zat Ion , Reaction ti>
Ammonia anJ Formate, Oxidation,
Metal Comi>lexatlon, Blodegr.iJ i-
tlon, Sorptlon, Formation of
Simple & Complex Compounds,
PhotodegradatIon of Fe & Co
Coinpl axes
— —I ~— - ' "\ W////////// ///////. .PAD/
/ /////
'////// A
, S 7 VPROCESS POND-y^X..-. 1 f /
£ f f ^VX, ..... ^SS POND SEEPAGE POTENTIAL '
^ L, i, LINER
I F
SEEPAGE POTENTIAL SEEPAGE POTENTIAL
1 ' 1
1 1 I
SOIL &
UNWE
~
,
Unsaturated Zone:
WEATHERED BEDROCK Volatilization, Reaction to
Ammonia and Formate, Oxldatlmi,
Hetal uomplexai Ion , Blodegrada-
ATHERED BEDROCK tlon, Sorptlon, Formation of
WATER
TABLE
Simple & Complex Compounds
T
Saturated Zone:
Reaction to Ammonia and Formate,
Metal Cotnplexatlon, Sorptlon,
Formation of Simple and Complex
Compounds, (VolatIzatIon i
BlodegradatIon - may be less
3 Ignlfleant)
VlF SULFIOE PRE3ENT:FORMATION OF THIOCYANATE
-------
cyanide flowed across soil for approximately 0.8 kilometer (0.5 mile).
The spill occurred in the spring when temperatures were cold and the
ground was partially frozen. The attenuation for free cyanide was a
two order magnitude decrease (Appendix D). Because data on attenuation
of cyanide in streams are not available, dilution will be the only
factor considered in this analysis for reducing the concentration of
cyanide once it enters the stream. This approach is very conservative
and does not recognize that chemical and biological processes will
continue to attenuate cyanide (Figure 20).
In the pond overflow example, the release occurs during a period
of heavy precipitation, and snowmelt runoff. The drainages under the
conditions are at annual peak flows. Therefore, considerable dilution
of the cyanide and heavy metals in the pregnant pond solution occurs.
The impacts of the spilled cyanide and metals on the environment are
assessed by comparing the resulting concentration of these substances
in the environment with EPA toxicity criteria for aquatic life, which
are the most stringent criteria in use.
Pond Leak
In the second example, the release of cyanide solution from the
pregnant pond occurs through a small leak in the pond liner and leak
detection system. The leak from the pond goes unnoticed until cyanide
is detected in the ground water at the monitoring well downgradient
from the process area. Little is known about the leak, including when
it started, the rate of leakage, or the total volume of pregnant pond
solution that has leaked from the pond. The concentrations of free and
total cyanide in the leaked solution (225 mg/1 and 250 mg/1, respec-
tively) are the same as in the pregnant pond solution. Metal concen-
trations in the leaked solution at the point of leakage are approxi-
mately 30 mg/1 iron, 5 mg/1 arsenic, 1 mg/1 cobalt, 1 mg/1 gold, and
0.005 mg/1 silver. The depth to ground water varies among sites from 6
to more than 100 meters (20 to more than 300 feet) below the ground
surface. The nearest surface water is approximately 0.8 kilometer (0.5
mile) distant. Connections between the ground water beneath the
pregnant pond and the surface water are unknown.
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ISSUES OF CONCERN
This evaluation considers all of the issues of concern resulting
from the placement of the hypothetical heap leach operation at the
three sites in the northern Black Hills, Including the issues resulting
from the two accidental releases of cyanide solution described above.
The significant issues evaluated to determine Impacts from the cyanide
heap leach facility include the following.
The effects the project will have on local water quality,
particularly including increases in erosion and sediment
production associated with mining activities and the possi-
bility of cyanide spills and contamination.
The extent to which streams in the study area are receiving
pollutants from past raining activities.
The provisions made to direct water away from the leaching
pads, pit areas, and ponds.
The extent of reclamation and revegetation of disturbed
areas.
The impacts of this project on the resident fisheries.
Whether the economic benefits of the project, including new
jobs, purchasing, and tax revenues, will offset potential
effects on local public services and utilities.
The long-term effects of the project on the local community
lifestyle.
The extent of growth (population and economic) that can be
expected.
The following sections address these issues by discussing the
Impacts of the hypothetical cyanide heap leach operation on the resour-
ces of the three drainages. Both construction and operational Impacts
and Impacts resulting from the two accidential release cases are
considered.
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GEOLOGICAL RESOURCES
The three mines are located in the Tertiary intrusive belt located
near the Lead Dome area. Ore will be mined from the Tertiary intru-
sives and associated Deadwood Formation in the mines along Whitewood
Creek and Bear Butte Creek and from the Tertiary intrusives and the
Pahasapa Limestone in the mine located in the Spearfish Creek drainage.
The ore deposits are medium to small vein and replacement deposits.
The potential impact to the geological resources is the loss of
the mineral resource due to mining. It is estimated that 13,500 metric
tons (15,000 short tons) of ore and waste rock will be mined daily.
The placement of waste-rock piles could inhibit access to ore in the
future. Because mineral resources are finite, the waste rock and
associated spent ore may eventually be further rained as mining tech-
nology advances and permit recovery of minerals from lower grade ores.
Potential impacts could also include mass failure. Mass failure
occurs when large masses of earth material, such as soil, rock, or
debris, are cohesively transported by gravity from one place to anoth-
er. Potential areas for mass failure are the mining pit area, waste
rock pile, haul roads, and leach pad site. By proper engineering and
the siting of waste rock piles, haul roads, and pads in suitable
locations, the potential for failure can be reduced or eliminated.
Impacts resulting from unavoidable alterations in topography would
also occur. The significance of such alterations would be site-speci-
fic and would depend in large part on post-project land uses.
The accidential release of cyanide either by spilling or by
leaking from the pregnant pond would not have significant impacts on
the geological resources at any of the three drainages.
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GROUND WATER
Mine Facility Construction and Operation
The major source of water for the mining operation in all three
drainages would be ground water from wells and/or springs. The mining
operation will initially use a large amount of water for process water.
Because evaporation exceeds precipitation In this region, a small
amount of water will continually be needed for additional process
water. Water will also be required for normal plant operations such as
plant facilities, domestic use, and road spraying. This use of ground
waters may result in a lowering of the ground water table, which could
adversely affect surrounding ground water users. Drawdown effects
depend on the distance between wells, rates of pumping, and the aqui-
fers used. Other ground water users will probably not be affected by
the hypothetical raining operations, based on the remoteness of the
locations for the mining operations and the lack of adjacent water
users. However, the possibility of adversely affecting others who use
ground water should be considered when evaluating actual proposed mine
sites.
The recharge areas for the aquifers at all three sites occur along
the aquifer outcrops. The 400 hectares (1,000 acres) disturbed by
mining would not significantly affect recharge.
The mining operation will mine near-surface ore from an open pit.
In some areas, the ground water table may be near-surface. If some of
the ore in the pit is below the ground water table, measures should be
taken to control ground water flow by pumping. The region is known to
contain numerous springs, so it is possible that springs fed by near-
surface aquifers disturbed by the mine pit may temporarily dry up or
experience water quality changes. Runoff and any ground water (if
present) will be pumped from collection sumps to a settling pond or
will be used In dust control on roads and dumps. If unexpected mine
dewatering problems are encountered during the course of mining, the
mining plan may need to be modified.
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If the ground water level beneath the heap pad and process area is
near the surface, design and installation of underdrains will be needed
to allow for flow of ground water. Heap stability in the case of
near-surface saturated conditions should also be considered in the
design.
During regular operations, the ground water quality of the three
drainage areas will not be affected. The heap leach operation and
processing plant have been designed and will be maintained as a totally
contained, no-discharge system.
Spearfish Creek
The major aquifer at Raspberry Gulch, the tributary to Spearfish
Creek where the mining operation will be located, is the Pahasapa
Formation. The depth to ground water ranges from near surface to
tens of meters (several hundred feet). The Whitewood Formation, a less
prolific aquifer, may also occur in the area.
Ground water is used by summer residences along Spearfish Creek
and the small developed areas near Deer Mountain and Terry Peak ski
areas. Ground water use by the mining operation may potentially affect
the alluvial aquifers used by the residences along Spearfish Creek
since ground waters from the Pahasapa Formation are reported to dis-
charge to the alluvium. The use of ground water by the mining opera-
tion may also affect the ground water use of nearby developed areas
which are using the same carbonate aquifer. The impact of ground water
use by the mine may be assessed by hydrologic tests to determine the
drawdown in aquifers used by the mining operation. Four deep aquifer
wells near Spearfish are used for the town's municipal water supply.
The wells are completed in the Pahasapa Limestone and the Minnelusa
Formation. It is unlikely, however, that drawdown from the mining
operation would extend to these wells.
Whitewood Creek
Ground water may occur in several different aquifers in the Yellow
Creek drainage, the tributary to Whitewood Creek where the mining
operation will be located. Potential aquifers are the Whitewood and
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Deadwood Formations, alluvium along Yellow Creek, and fractured Pro-
terozoic metasedimentary and metavolcanic rocks. Ground water depths
are estimated to be from near surface to tens of meters (several
hundred feet).
Ground water use is limited in this area, which is located just
west of the Grizzly Gulch tailings impoundment. The nearest develop-
ment is Pluma where several residences are located. It is not known
whether these homes are dependent on ground water for water supply.
The towns of Lead and Deadwood obtain their water from springs.
Withdrawal of ground water for the mine would not be likely to affect
these low-volume users, but impacts would depend on which aquifers are
used and the distance to adjacent water users.
The ground water quality of Yellow Creek may be of poorer quality
than that of the other two drainages. The Wasp No. 2 Mine, the third
largest mine in the Black Hills (refer to Chapter 3), is located in
the Yellow Creek drainage. A hydrological study of both surface and
ground water conditions would establish baseline hydrological condi-
tions for this drainage.
Bear Butte Creek
Potential aquifers that may be used as a water supply for the
mining operation in the Two Bit Creek drainage, the tributary to Bear
Butte Creek, are the Pahasapa Limestone, Whitewood Formation, Deadwood
Formation, and, possibly, Tertiary intrusives. Depths to ground water
probably range from near surface to tens of meters (several hundred
feet).
Several recreational residences may use alluvial ground water for
water supply on Peedee Gulch and the headwaters of Two Bit Gulch. The
impact of the mining operation's ground water use on the residences'
alluvial supply will probably be minor, but will depend on which
aquifers are used and the distance to adjacent water users. Deep water
wells used by the town of Sturgis, which are completed in the Pahasapa
Limestone and Minnelusa Formation, would be too distant to be affected
by drawdown at the mining operation.
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Accidental Releases
Of the two hypothetical releases, the pond overflow and leak, only
the pond leak will affect ground water resources. Cyanide or metals
from the pregnant pond overflow will not impact either the vadose zone
or ground water. As a result of the pond leak, cyanide has been
detected in the monitoring well downgradient of the heap leach and
process areas. This discussion will focus on the factors which may
affect the attenuation of cyanide in ground water, since there are not
enough data to create a specific model for each drainage.
The following examples of leaks from heap leach mining operations
are discussed to allow for quantification of the hypothetical pond
leak. A spill and pond liner leak combination in Montana with 35 mg/1
total cyanide and 27 mg/1 chlorine amenable cyanide at the point of
loss was detected in an alluvial well 0.40 kilometer (0.25 mile) away
(Appendix D). The highest concentrations of cyanide detected in the
well were 0.119 mg/1 total cyanide and 0.14 mg/1 chlorine-amenable
cyanide which were detected 6 months after the accident. The cyanide
has since dissipated. At a heap leach operation in Elk City, Idaho, 9
to 10 mg/1 total cyanide and 1 mg/1 weak-acid-dissociable cyanide were
detected in a monitoring well (Appendix D). The concentration of the
process solution that was the source of the leak is unknown. Apparent-
ly the cyanide had dissipated to below detection levels within 30 to 45
meters (100 to 150 feet) downgradient from where it had been detected
in the monitoring well.
The movement and concentration of cyanide in the ground water from
the leak at the hypothetical heap leach operation will be a function of
the depth to ground water, dilution, characteristics of the soil and
aquifer media, and the hydraulic conductivity of the aquifer. The
chemical processes that control the transformation and reaction of
cyanide depend on pH, temperature, concentration and types of metals
present in solution and in the soils and subsequent formation of metal
cyanide complexes, amount of aeration, and interaction with soil or
rock particles (Appendix B).
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The depth to water ranges from near surface to tens of meters
(several hundred feet) at the three locations selected for the mining
operation. If the pond site selected for the mining operation has
near-surface ground water, there will be less chance for attenuation of
cyanide through soil and/or bedrock in the vadose zone. Important
processes for the attenuation of cyanide in the vadose zone may be
volatilization, complexing with metal ions, biological degradation,
dispersion, and possibly sorption. Volatilization and biodegradation
may become less important with depth. The vadose zone medium in the
mine site area will consist of a thin layer of soil and underlying
bedrock.
The soil factors responsible for the attenuation of cyanide are
clay content, soil depth, soil pH, content of hydrous metal oxides,
presence of oxygen, and concentration of organic matter. The section
on environmental impacts to soil from a surface spill discusses these
factors in detail. No data exist on the attenuation of cyanide through
different rock types. Based on the extrapolation of the soil data,
rock types containing clays and hydrous metals oxides may attenuate
cyanide more than those that do not. Once in the bedrock vadose zone,
the specific type of bedrock will control path length and routing,
which affects the time available for attenuation and the quantity of
material encountered. The amount of fracturing or jointing will affect
the routing.
If the cyanide reaches the ground water, the net recharge and the
physical characteristics of the aquifer will be important controls on
the amount of cyanide and its dispersion in the aquifer. Low recharge
rates and low transraissivities would both result in little dilution and
slow movement of the cyanide in the aquifer. The characteristics of
the aquifer under the proposed mine sites are discussed in the follow-
ing paragraphs.
The alluvial deposits are discontinuous unconsolidated stream
channel, overbank, and flood deposits containing gravel, sand, and
silt. Alluvial deposits such as channel deposits containing more
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coarse-grained material (more permeability and less attenuation) have a
greater potential for cyanide transport than deposits containing
fine-grained materials. The potential exists for cyanide in the
alluvium to be transported to underlying aquifers since they may be
hydraulically connected. Alluvial ground water and surface water may
also interact, possibly resulting in the introduction of cyanide into
the surface water system.
Ground water in the carbonate aquifers (Pahasapa and Whitewood
Formations), occurs in openings ranging from small pores, joints,
and fractures up to large solution openings such as caverns. As with
other bedrock aquifers, the extent of these openings influences the
rate and extent of cyanide transport through the system. The Pahasapa
Formation is recharged by precipitation, streamflow losses, and leakage
from overlying aquifers at a net rate of 170 millimeters (6.8 inches)
per year. This recharge rate is probably considerably greater than
that of other bedrock aquifers in the Black Hills, so that a larger
quantity of water may be available for dilution in this aquifer than in
others. The cavernous portions of the carbonate aquifer may have high
hydraulic conductivities, which have the potential for moving cyanide
quickly away from the leak area and dispersing it through a large area.
In addition, cyanide is more mobile in the higher pH ranges typical of
carbonate aquifers than in aquifers having low pH values.
The sandstone aquifer, the Deadwood Formation, yields small to
moderate amounts of good to saline water. The mobility of cyanide in
the aquifer is largely controlled by both the degree of fracturing and
the primary porosity of the sandstone.
Aquifers in the Proterozoic metasediraentary and metavolcanic rocks
and the Tertiary igneous intrusives are metamorphie/igneous aquifers.
These types of rocks have little or no primary porosity so that water
can be obtained only from fractures within the rock. If wells are
present in these aquifers, yields would be low. The relative mobility
for cyanide in these aquifers is a function of the degree of fractur-
ing.
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SURFACE WATER
The effects of the mining project on surface water resources are
primarily related to increased erosion and sedimentation caused by
surface disturbance associated with mining and road construction
activities, and potential accidental releases of hazardous chemicals.
Specific areas of water quality concern include sediment production
from roads and dump areas, heavy metal contamination, and cyanide
spills.
Mine Facility Construction and Operation
During the construction phase of the heap leach facility, a
short-term increase in sediment production would be an unavoidable
effect. Increased erosion and sedimentation resulting from road
construction and mine operation is expected to be controlled by the
settling ponds, drainage diversions, and other standard sediment
control structures.
Sizes and locations of haul roads affect the amount of sediment
produced and the likelihood of it reaching a stream. Roads constructed
on slopes or ridges away from stream channels can have half the sedi-
ment generating potential of streamside roads. Side casting of road
material on steeper slopes (50 percent or greater) has the potential to
greatly accelerate the erosion rate.
The waste dump area is also potentially a source of high sediment
production and water quality degradation. The steepness of the terrain
and the unpredictable nature of the runoff patterns require care in the
selection of the disposal site. Any filling of natural channels would
increase the potential for flooding, mass failure, and sedimentation
problems. Hillside dumps may also be difficult to stabilize, could
have a long-term adverse impact on water quality, and prove difficult
to reclaim. Long-term erosion of waste rock piles and spent ore
depends on configuration, susceptibility of coarse fragments to
weathering, and revegetation success.
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Accidental Releases
In the event of a spill of chemical-laden water from a mine
structure (such as the overflow from the pregnant pond), the effect on
surface water would depend on the amount of dilution and attenuation
occurring. As discussed previously, cyanide from an actual spill at a
concentration similar to that overflowing the pregnant pond at the
hypothetical mine was reduced by two orders of magnitude as it flowed
over the ground for 0.8 kilometer (0.5 mile). In this analyses, only
dilution is used to reduce cyanide concentrations once the cyanide
enters the stream since actual data on cyanide attenuation in streams
are lacking. This is a conservative approach since many chemical and
biological processes will continue to reduce free cyanide concentra-
tions. Potential impacts of the pond overflow described earlier to
Spearfish Creek, Whitewood Creek and Bear Butte Creek are discussed
below by drainage.
In the event of a leak beneath the pond lining or heap, the
primary release of cyanide would be to the ground water. Because of
attenuation, it is unlikely that detectable concentrations of cyanide
would be discharged from the ground water to the surface water.
Discharge of cyanide from ground water to surface water would depend on
the amount of attenuation in the vadose zone and in the aquifer, the
distance traveled to surface water, and the amount of flow into surface
water.
Spearfish Creek
At the Spearfish Creek drainage mine site, the spill of 100 cubic
meters at 2.8 liters per second (27,000 gallons at 45 gallons per
minute) would cross the vegetated ground surface for approximately 0.8
kilometer (0.5 mile) and enter Raspberry Gulch. Initially, the concen-
tration of free cyanide in the spill would be approximately 200 mg/1.
After flowing over the ground surface, the free cyanide concentration
would be reduced by two orders of magnitude, based on the attenuation
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factor discussed in Appendix D. The free cyanide content just before
the spill entered the tributary (2 mg/1) would be about 2 orders of
magnitude higher than the acute toxicity level for aquatic life (0.022
mg/1).
Raspberry Gulch flows for approximately 2 kilometers (1 mile) and
enters Spearfish Creek. Assuming the average yearly high flow of
Raspberry Gulch is about 0.1 cubic meter per second (5 cfs), the free
cyanide concentration would be reduced an additional order of magnitude
by dilution. Assuming an average yearly high flow in Spearfish Creek
of 4.2 cubic meters per second (150 cfs), dilution upon entering
Spearfish Creek would reduce free cyanide concentration by another
order of magnitude in the range of acute toxicity level for aquatic
life (0.022 mg/1). Dilution would reduce levels of cyanide in Spear-
fish Creek to below the chronic aquatic toxicity level of 0.005 mg/1
further downstream from the Raspberry Gulch confluence. The town of
Spearfish uses Spearfish Creek as a source of drinking water. Based on
these assumptions, the cyanide content of Spearfish Creek at Spearfish
will not exceed the EPA (1985) ambient water quality criterion for
cyanide of 0.2 mg/1 (free cyanide).
The process solution released also contains metal cyanide com-
plexes and ions such as sodium and arsenic in solution. Arsenic does
not form a metal cyanide complex. The concentration of arsenic, which
would be diluted by more than two orders of magnitude would be below
the EPA acute and chronic toxicity level for aquatic levels (0.36 rag/1
and 0.19 mg/1, respectively) in Spearfish Creek immediately downstream
from the confluence with Raspberry Gulch.
Most of complexed metal is iron, which forms a strong complex with
cyanide. The concentration of iron is initially about 25 mg/1. Dilu-
tion would reduce this level by two orders of magnitude at Spearfish
Creek just below its confluence with Raspberry Gulch to below the EPA
aquatic life toxicity level for iron of 1 mg/1. Ultraviolet light may
cause iron and cobalt cyanide complexes to photodecompose and release
cyanide and free iron or cobalt. The rate of photodecomposition in
deeper, turbid waters is not known. The half life for ferricyanide
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(Fe(CN,) ) based on experimental data (Siraovic et al., 1985) is 6.1
o
and 20.6 days for solutions at 4° G (39° F) and 20° C (68° F), respec-
tively (refer to Appendix B, Table B-6). Assuming a stream velocity of
0.3 meter (1 foot per second) for the accidental spill discussed above,
the spill would take about 2 hours to reach the mouth of Raspberry
Gulch. Based on these data, the amount of free cyanide released from
the degradation of ferricyanide as the spill travels downstream would
be very small. No experimental data exist for cobalt cyanide complex,
but probably the degradation rate would be similar to ferricyanide.
Aquatic toxicity levels for cobalt have not been proposed by the EPA.
Other metals in the spill are gold and silver at concentrations of
approximately 1 mg/1 and 0.004 mg/1, respectively. These metals form
strong complexes with cyanide. Conservatively estimating the concen-
tration of the metals released from the metal cyanide complexes based
only on dilution, concentrations of gold and silver would be reduced by
2 orders of magnitude at Spearfish Creek just downstream from its
confluence with Raspberry Gulch. Aquatic toxicity levels for gold have
not been proposed by the EPA. However, gold is very non-reactive and
generally has a very low toxicity for biota. Assuming the silver
cyanide complex completely dissociates to free silver, the content of
silver in Raspberry Gulch would be below the EPA acute toxicity level
for aquatic life of 0.013 mg/1. In Spearfish Creek downstream from the
confluence with Raspberry Gulch, the silver content would be below the
EPA chronic toxicity level for aquatic life of 0.00012 mg/1. The free
cyanide released from the gold and silver complexes would be insignifi-
cant considering dilution.
Whitewood Creek
For a spill occurring on Yellow Creek, a tributary to Whitewood
Creek, the environmental effects would be similar to those in Spearfish
Creek. The distance between the site of the described spill and the
confluence of Yellow Creek with Whitewood Creek is about 3 kilometers
(2 miles).
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Concentrations of free cyanide and metal cyanide complexes from
the spill in Yellow Creek, with an assumed yearly high flow of 0.4
cubic meters per second (15 cfs), would be diluted by approximately two
orders of magnitude. Assuming an average yearly high flow of 5.5 cubic
meters per second (200 cfs) and 3.5 cubic meters per second (125 cfs)
for Whitewood Creek at Deadwood and at Whitewood, respectively, free
cyanide from the spill would be reduced in Whitewood Creek to below
both the acute and chronic aquatic toxicity levels in the reach down-
stream from the confluence of Yellow Creek and the town of Deadwood.
Past and ongoing mining activities may contribute cyanide to
Whitewood Creek. U.S. Geological Survey data (1983) in the vicinity of
the town of Whitewood show total cyanide concentrations ranging from
less than 0.01 mg/1 to as high as 0.24 mg/1 total cyanide (filtered
sample). No sampling was done in the Deadwood area during the same
time period. Homestake Mining Company has a permit for Whitewood Creek
above Deadwood to discharge a treated waste stream containing 1.8 rag/1
total cyanide from their wastewater treatment plant. The contribution
of cyanide from the spill would not be noticeable when compared to
background levels.
Impacts from metals and cyanide released from metal cyanide
complexes at Raspberry Gulch would be very similar for Yellow Creek.
If metals were released from iron and silver cyanide complexes in the
spill, the concentrations of iron and silver in Yellow Creek upstream
from its confluence with Whitewood Creek would be below toxicity levels
for aquatic life. No aquatic toxicity levels for cobalt or gold have
been proposed by the EPA. Arsenic levels in Yellow Creek from the
spill would be below EPA toxicity levels for aquatic life. Background
levels of arsenic, however, may be elevated because of past mining
activities. For example, the dissolved arsenic concentration of
Whitewood Creek in the vicinity of Whitewood ranges from less than 10
to 62 mg/1 (U.S. Geological Survey, 1983). Effects of arsenic from the
spill would be undetectable compared to background levels of arsenic in
the drainages.
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Bear Butte Creek
A spill from a mining operation located in Two Bit Creek would
flow into Boulder Creek, and then into Bear Butte Creek. The effects
would be similar to those discussed for the other two drainages. The
spill would flow into Two Bit Creek, which has an average yearly high
flow of 0.4 cubic meters per second (15 cfs), and travel downstream for
about 3 kilometers (2 miles) to the confluence with Boulder Creek,
which has a high flow of 0.3 cubic meters per second (10 cfs) above the
confluence. Boulder Creek joins Bear Butte Creek after about 2 kilo-
meters (1 mile). The level of free cyanide downstream from the mouth
of Two Bit Creek would be reduced by approximately four orders of
magnitude from the original spill, with a reduction of two orders of
magnitude resulting from dilution and two orders of magnitude resulting
from attenuation during overland flow. The free cyanide content would
be in the range of the acute toxiclty level for aquatic life (0.022
mg/1). The flow of Bear Butte Creek downstream from the Boulder Creek
confluence is about 1 cubic meter per second (40 cfs) during high flow.
Bear Butte Creek has an average yearly high flow of about 3 cubic
meters per second (100 cfs) at Sturgis, which is approximately 8
kilometers (5 miles) downstream from the Boulder Creek confluence.
Based on dilution only, free cyanide below Sturgis would be reduced to
a concentration in the range of the chronic toxicity level for aquatic
life.
The impacts of metal cyanide complexes and arsenic would generally
be the same as for Spearfish and Whitewood Creeks. If the metal
cyanide complexes (iron and silver cyanide complexes) dissociate and
release metals, the levels of iron and silver would be reduced by
dilution to below levels toxic to aquatic life in Two Bit Creek up-
stream from its confluence with Boulder Creek. No aquatic toxicity
levels for cobalt or gold have been proposed by the EPA. Small amounts
of free cyanide will also be released and be diluted to below toxic
levels. Arsenic levels in Two Bit Creek from the spill would be below
EPA chronic toxicity levels (0.19 mg/1).
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SOILS
Mine Facility Construction and Operation
Soils impacts resulting from construction of the cyanide heap
leach and processing facilities will be similar in type and magnitude
in all the three drainages because of similarities in soil and topo-
graphic characteristics. The major impacts to soils will result from
removal, compaction, or other in-place disturbance of soils during the
construction of the facility. In this example, 400 hectares (1,000
acres) will be disturbed.
Suitable growing material (topsoil) varying in depth from 40 to
150 centimeters (15 to 60 inches) will be stockpiled and protected from
erosion for subsequent use during reclamation. Assuming a soil removal
depth of between 46 and 91 centimeters (18 and 36 inches), between 1.2
and 3.7 million cubic meters (1.6 and 4.8 million cubic yards) of
material could be removed and stockpiled during the project life.
Soil resource values potentially affected by mine development
include alteration of soil structure, compaction, interruptions in soil
microbial activity, erosion by wind and water, changes in soil nutrient
status and fertility, and reduced vegetation restoration potential.
Dramatic disturbance in the inherent soil structure by removal or
compaction during construction, could result in reduced water infil-
tration rates, disruptions of nutrient cycles and microbial activity,
and increased erosion hazards. The effects would be temporary until
stockpiled and compacted soil was reclaimed and/or revegetated. Root
development and increased microbiological activity would improve soil
structure and enhance vegetative growth.
When the litter layer is completely removed during facility
construction, or compaction is caused by vehicle movement, water
infiltration into the soil is decreased. This will produce a greater
amount of overland flow and, hence, more runoff energy will become
available to produce surface soil erosion (U.S. Environmental Protec-
tion Agency, 1980). Without appropriate sediment-control structures,
this increased soil loss could become a major source of non-point
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pollution (Fredriksen, 1972). Nutrients essential to plant growth will
be less solubilized because of reductions in soil moisture caused by
compaction. The impacts of soil disturbances on vegetation restoration
potential will be temporary if controlled. However, if construction
activities result in excessive losses of soil, reduced nutrient levels,
and a decline in soil structure, long-term, significant impacts to
plant community restoration potential could occur.
Certain portions of the mine pit will not be reclaimed. There-
fore, these areas will experience long-term, possibly irreversible
losses of soil resources. Areas slated for reclamation following the
life of the project will experience only short-term effects.
Accidental Releases
The effects on soils as a result of the pond overflow would be
limited to the immediate area of overland flow. As discussed in
surface water, cyanide is reduced by dilution in the major streams so
that there would be little, if any, effect on downstream flood plain
soils. In investigations of actual spills, little cyanide was detected
in the soil.
Some of the spilled process water may infiltrate into the soil.
However, because most of the soil profile would still be frozen during
the spring snowmelt period when the spill occurred, infiltration would
be limited. If most of the soil profile had thawed, the depths of
infiltration would depend on soil permeability and soil depth. The
dominant soils at all three locations have permeabilities ranging from
—2 —6
low to moderate (10 to 10 centimeters per second). The soils are
approximately 150 centimeters (60 inches) deep.
If the spill enters the soil zone, the mobility of cyanide will
depend on characteristics of the soil such as the clay depth, pH,
existence of aerobic or anaerobic conditions, presence of soil organic
matter, and content of hydrous oxides (Fuller, 1985). Appendix B
provides a general discussion of cyanide movement in the soil. The
clay content in the surface horizons most susceptible to contact with
cyanide ranges from 7 to more than 20 percent in the three drainages.
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Many of the clays are kaolin!tic in nature, which would tend to reduce
mobility of cyanide more than montmorillonitic clay (Huiatt et al.,
1976). Montmorillonite clays are more abundant at deeper depths within
the soil profile. Clay content increases with depth, further immobi-
lizing cyanide.
Volatilization of hydrogen cyanide will occur in soils at the
three sites, since the pH of the soils ranges from neutral to moderate-
ly alkaline. Cyanide will be more mobile in soils with the higher
(more alkaline) pH values. The absence of calcium carbonate in large
quantities in the upper 25 to 30 centimeters (10 to 12 inches) of most
study area soils would also aid in immobilizing cyanide. Should
cyanide infiltrate to below this depth, calcium carbonate may activate
the cyanide ion (Alesii and Fuller, 1976).
The soil conditions at the three sites are aerobic. Under aerobic
conditions, cyanide will move only a short distance before being
biologically converted to nitrate (Huiatt et al. , 1983). Organic
matter on the surface will attenuate cyanide, promoting rapid breakdown
by micro-organisms.
The content of iron oxides in the soils is insignificant in the
Bear Butte and Spearfish Creek drainages, and will not greatly influ-
ence cyanide mobility. Iron content is higher in the lower Whitewood
Creek drainage. The presence of iron and its influence on cyanide
movement is minimal, however, at the Whitewood Creek site.
The metals, iron, arsenic, gold, silver, and cobalt, in the
spilled process solution will have little impact on soil. The concen-
trations of the metals will be far below levels considered toxic to
plants or animals (U.S. Environmental Protection Agency, 1983). Most
of the arsenic will be bound by clays, hydrous iron oxides, and organic
matter in the surface horizons of the soils at the three sites.
The soil conditions in the study area suggest that movement of
cyanide and its complexes will be rapidly attenuated at all three
sites. Additionally, the effects of the spill on soils would be
localized and not extend off the project site. Discharges at the three
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sites, based on the best available information presented in Appendix B,
could cause insignificant short-terra increases in soil pH and decreased
microbial activity. Permeability and structure may not be affected
because the example spill occurs in the early spring under near-frozen
soil conditions. Long-term productivity of vegetation or soil micro-
bial populations would not be impaired. Nutrient levels in soils
should not be affected either in the short or long term. Water quality
also will not be affected by an increase in the levels of cyanide in
soil because of the many processes that degrade cyanide as it makes
contact with the soil.
In the example of the pond leak, an undetected plume of pregnant
pond solution seeps into the ground water. During construction, all
soil suitable for use as a growing medium has been removed near or to
bedrock. Therefore, impacts to soils in the plant root zone (solum)
are not significant, as these soils have been removed and stockpiled
for later reclamation. The effects on the soil remaining beneath ponds
or heap pads are a function of the factors discussed in the pond over-
flow example. Some examples of leaks at heap leach mining operations
provide an estimate of the extent of soil impacts. At the American
Mine, liner failures occurred and free cyanide concentrations of up to
300 mg/1 were measured in soil cores below the ponds. The maximum
depth of free cyanide detection was 61 centimeters (24 inches).
Maximum soil penetration of cyanide was approximately the same below
leaks in PVC liners under inactive heaps at the same mining operation.
VEGETATION
Mine Facility Construction and Operation
General vegetation impacts resulting from construction of mining
and process facilities in the Spearfish Creek, Whitewood Creek, or Bear
Butte Creek watersheds would be similar for each drainage. Construc-
tion would directly affect vegetation through removal or through
partial destruction by construction equipment and other vehicles.
In this example, approximately 400 hectares (1,000 acres) of native
vegetation could be affected in each watershed.
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Vegetation resource values potentially affected by mine develop-
ment include plant productivity, nutrient cycling, microclimate influ-
ences, habitat, ecosystem structure, erosion control, and esthetics.
Based on regional relative abundances of vegetation types, the majority
of the effects would result to ponderosa pine forests. Several acres
of mountain grassland or riparian vegetation could also be affected.
Operational effects of heap leach mining on vegetation could
result from wind-blown cyanide spray from the heap leach pile. How-
ever, the spray process would probably be halted during strong winds so
the effect of cyanide spray on vegetation should be negligible.
Standard reclamation and revegetation practices would serve to
reduce the effects of the project. However, because only portions of
the mine pit would be reclaimed, residual impacts on vegetation
resources would remain. Construction of roadways, ponds, and other
minor facilities could also result in impacts on vegetation throughout
the life of the project. Disturbance associated with pipeline burial,
transmission tower construction, and slopes adjacent to access routes
would be revegetated soon after construction. Therefore, only short-
term impacts resulting from direct disturbances would be associated
with these activities.
Secondary impacts associated with human population growth and
activity could significantly affect vegetation resource values outside
the mining area as a result of urban expansion, accidental range and
forest fires, and increased off-road vehicle (ORV) use.
If project facilities are developed in or adjacent to stream
tributaries, direct and secondary effects on plant species of special
concern could occur. Rare plant species could occur along watershed
drainages. Direct disturbances to these plant populations or changes
in surface water quality or quantity could reduce their viability or
numbers. Locations of populations of special concern plant species
should be considered in project planning and design.
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Accidental Releases
The hypothetical leak in the pond liner which results in contami-
nation of the ground water under the pregnant pond should have an
insignificant impact on vegetation resources. If the depth to ground
water is less than 40 feet, some trees and shrubs with roots near or in
the ground water aquifer could come into contact with the affected
ground water. However, cyanide concentrations in ground water would be
rapidly attenuated. Therefore, the adverse effects on vegetation would
be localized and minimal. By the time the ground water reached the
surface water bodies, the concentrations of cyanide would be below
those harmful to plants.
The hypothetical pond spill would result in 100,000 liters (27,000
gallons) of pregnant pond solution flowing overland 0.8 kilometer (0.5
mile) to a tributary. Many physical and environmental factors would
influence the effects of the spill on vegetation. Cyanide concentra-
tions could be rapidly attenuated by the soil. Slope characteristics,
plant density, and plant community composition would affect the rate of
overland flow and the extent of vegetation affected. It is probable
that vegetation in the immediate vicinity of the spill source would be
adversely affected, as discussed in Appendix C. Concentrations of 200
mg/1 cyanide could result in complete or partial loss of plants in the
immediate area (Stanton et al., 1985). Depending on the plant species
present and the concentration of cyanide reaching the waterway, ripar-
ian vegetation and plant species of special concern occurring imme-
diately adjacent to the stream could also be adversely affected. The
concentrations of cyanide and physiological effects of cyanide on
plants are discussed in Appendix C. By the time the solution reached
agricultural areas at lower elevations in and adjacent to the Black
Hills, concentrations of cyanide would be reduced to levels that would
not be toxic to crops.
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WILDLIFE
Mine Facilities Construction and Operation
Potential effects resulting from the construction and operation of
the heap leach mine operation could include habitat removal, habitat
degradation, and direct wildlife mortality. Habitat removal refers to
the loss of available habitat through conversion of present land uses
to other uses. Habitat degradation occurs when habitat is left in
place but its quality is reduced. Factors affecting habitat quality
include decreased water quality and increased noise, human presence,
and soil erosion. Direct mortality results from increases in legal and
illegal hunting, road kills, and exposure to toxic chemicals.
Approximately 400 hectares (1,000 acres) would be stripped of
vegetation and converted to project uses for the life of the project.
The effects of this conversion would depend on the actual project
layout (a solid block or dispersed areas connected by roads), vegeta-
tion types present, areal extent of each vegetation type, local wild-
life assemblage, and the presence of unique wildlife species, habitats,
and features. Generally, loss of vegetation causes a reduction in
local wildlife populations associated with the removed vegetation.
Because ponderosa pine would probably account for most of the
vegetation loss at all three sites, the removal would primarily affect
wildlife associated with ponderosa pine, such as deer, porcupines, red
squirrels, turkeys, and red-tailed hawks. The effects on wildlife
species associated with the other vegetation types occurring in the
Black Hills environment would depend on how much of each type is
removed. Each of the three sites are located In winter range. The
Yellow Creek and Two Bit Creek sites are also located in year-round elk
range. Species of special concern associated with upland vegetation
types, such as mountain lion and black bear, could also lose habitat to
land use conversion if they occur on any of the sites.
The effects of the removal of 400 hectares (1,000 acres) of
wildlife habitat for the duration of the project could range from
insignificant to potentially significant for all three sites depending
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on the wildlife group present. For most species and wildlife groups,
the loss would probably not be significant because they occur in a
variety of vegetation types and are widely dispersed, highly mobile,
and abundant. However, the loss of 400 hectares (1,000 acres) of
critical deer winter range and elk range could be significant because
both are limited in the area. Their loss could reduce the potential
for these popular game animals to maintain or increase present herd
sizes.
If any species of special concern occurs on the sites, the conver-
sion of its habitat to project uses could be significant. Habitat loss
is one of the primary causes of the population decreases experienced by
most special concern species. In addition, limited available habitat
is one of the factors restraining the expansion of many special concern
populations.
General degradation of habitat around the mine would be similar
for each site. Construction of diversion ditches and sediment ponds is
expected to prevent or mitigate soil erosion and its associated water
quality impacts on wildlife. Increases in noise and human presence
generally elicit an avoidance response in wildlife. This response is
more pronounced in some species such as deer, elk, and some species of
special concern such as eagles. The potential for habitat degradation
may be relatively greater at the Two Bit Creek site because there is
currently less human development in that watershed than in the other
two watersheds where the hypothetical mine is located.
Elk are widely recognized as being sensitive to human disturbance.
The intrusion of roads, recreation areas, and mining, logging, and
hunting activities into otherwise attractive habitat can displace elk.
The magnitude of this displacement can be quite large. Studies of elk
movement and habitat utilization responses to human disturbance suggest
that elk maintain a buffer zone of approximately 500 to 1000 meters
(550 to 1100 yards) around the human disturbance (Ward et al., 1978;
Edge and Marcura, 1985; Lyon et al. , 1985). Therefore, where main-
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tenance of elk habitat quality and security is an important considera-
tion, adequate buffer zones around human disturbances are important
considerations in maintaining habitat integrity.
The effects of increased noise and human presence at each site
could range from insignificant to significant depending on factors such
as project facility layout (one large area or several dispersed areas
with roads between), the number of sensitive species (deer, elk, and
species of special concern) using the site and surrounding areas,
available buffer zones, and the amount of noise and general disturb-
ance. Deer could be affected at all three sites while elk could
potentially experience impacts at the Yellow Creek and Two Bit Creek
sites. If any species of special concern occur on the sites, habitat
degradation could cause sensitive species to abandon the immediate
area. This abandonment would have the same results as habitat removal.
Therefore, effects of habitat degradation on species of special concern
using the sites could be significant.
Direct mortality increases are not expected to significantly
affect wildlife at any of the three sites. Only relatively minor
increases in road kills and hunting mortality are expected from the
slight human population gain.
Once the mine and processing facilities are in operation, unre-
stricted access to the heap and open ponds could cause some loss of
wildlife due to consumption of cyanide solution. However, the proposed
fencing of the heap, ponds, and processing area, flagging of the barren
and pregnant ponds, and filling of collection ditches with rock will
minimize access to and subsequent consumption of the cyanide solution
by wildlife. Therefore, intoxication from the cyanide processing
facilities should pose little threat to wildlife at any of the three
sites.
Wildlife may be exposed to potentially toxic concentrations of
cyanide (250 mg/1 total cyanide) through wind drift during the spray
application of solution. The degree of this exposure depends on the
strength and direction of the wind (which determines the volume and
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distance the solution is carried outside the processing area), time of
day, and season (which influences which wildlife species may be
present). Wind drift will probably not be a significant pathway for
wildlife exposure because operators generally turn the sprayers down or
off during windy conditions to prevent the loss of their leaching
solution. This action would limit the amount of drifted solution that
would be available for ingestion.
Accidental Releases
The leak from the pregnant pond liner would not produce any
impacts to wildlife species in the area. The leaked solution could
enter the ground water system but would be unavailable to wildlife
species. If the contaminated ground water eventually discharged to
surface water, the toxic substances would be sufficiently diluted and
attenuated so as to not pose any threat to wildlife.
In the case of pregnant pond overflow, two types of solution
components could be of concern. The spilled solution consists of free
cyanide, metallic cyanide complexes, and arsenic. Small amounts of
dissolved forms of heavy metals (cobalt, iron, silver, and gold) may be
released from the metallic cyanide complexes. Potential effects of
cyanide and the metals are discussed below. The number of wildlife
species and individuals exposed to potentially toxic levels of contami-
nants from the overflow are variable and difficult to determine without
site-specific information.
Cyanide
Effects of cyanide on wildlife are described in Appendix C.
Lethal threshold concentrations vary among species tested. Free
cyanide at 3.0 mg/kg and 0.1 mg/kg were reported to be toxic to mice
and birds, respectively. However, rats fed diets containing as much as
1,500 ppm potassium cyanide showed few signs of toxicity (Feigley et
al., 1985). Research with dogs indicates that large doses of sodium
cyanide (0.5 to 2.0 mg/kg) administered periodically are tolerated.
These results, combined with the observations that cyanides are not
accumulated or stored and that many species of plants commonly eaten by
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wildlife synthesize cyanogenic glycosides (Appendix B), suggest that
animals are able to metabolize and detoxify both free and complexed
cyanide.
The spilled process solution at each site crosses about 0.8
kilometer (0.5 mile) of vegetated ground and enters a flowing tribu-
tary. The concentration of free cyanide (initially 200 mg/1) is
reduced two orders of magnitude, to about 2 mg/1, by the time it enters
a creek. Upon entering Raspberry Gulch, Yellow Creek, or Two Bit
Creek, the concentration is further reduced by dilution. Based on
threshold concentrations reported in the literature (Appendix C) only
the overland flow of solutions would contain concentrations of cyanide
that could measurably affect wildlife. Therefore, only the overland
flow is discussed further.
The primary pathway for wildlife exposure would involve animals
drinking the solution. Virtually any species that occurs near the
sites could come into contact with the solution during its period of
overland travel. Large mammals, furbearers, small mammals, and song-
birds would be the wildlife groups most likely to be affected because
they are the groups most likely to come into physical contact with and
drink the overland flows of solution. Songbird exposure would be
minimal if the overflow occurred at night when most birds are inactive.
Effects could range from minor to lethal, depending on the species, its
threshold tolerance, the volume of solution ingested, and point of
contact. Point of contact is important because the free cyanide
concentration decreases from 200 mg/1 to about 2 mg/1 as it flows
across the 0.8 kilometer (0.5 mile) of upland habitat.
Metals
Of the five metals that may occur in the cyanide solution, only
arsenic would cause concern to wildlife species. Iron, cobalt, gold,
and silver present few hazards to wildlife because they are either
relatively nontoxic to warm-blooded animals or they have extremely low
solubility characteristics and are essentially immobile.
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Although documented wildlife-related effects of arsenic toxicity
are rare (Deraayo et al. , 1979), livestock mortality associated with the
consumption of arsenic-contaminated soils and/or vegetation (Gough et
al., 1979) and public health problems associated with the consumption
of contaminated water by man have been reported. Arsenic compounds do
not accumulate in mammals (Vallee et al. , 1960). Differences in
arsenic toxicity do exist and have been correlated with animal excre-
tion rates; compounds that are slowly excreted tend to be the most
toxic (Vallee et al., 1960). The biological half-life for excretion of
arsenic compounds are reported to range from 30 to 60 hours (Sullivan,
1969). The lethal dosage of arsenic for sheep has been reported as 3.4
ppm (Berry and Wallace, 1974) while the acute lethal dose for rats is
13 ppm (Sullivan, 1969).
The concentration of arsenic in the leaked solution (4 mg/1) would
be diluted by one order of magnitude as it entered Raspberry Gulch by
two orders of manitude as it entered Yellow Creek or Two Bit Creek.
This reduction would result in concentrations that are below toxic
levels to wildlife. Therefore, as with cyanide, the overland flow
would be of primary concern.
The primary pathway for wildlife contamination from the overland
flow would be drinking contaminated water. Effects would depend on the
amount ingested, species involved, the chemical form of the arsenic,
and the arsenic concentration of the ingested solution. Wildlife
groups most likely to drink the solution include large mammals, fur-
bearers, small mammals, and songbirds. Effects are not likely to be
lethal, based on the low initial concentration and dilution. Secondary
contamination via the food chain is not likely because arsenic com-
pounds have not been shown to accumulate (Vallee et al., 1960).
AQUATIC RESOURCES
Mine Facilities Construction and Operation
Soil erosion caused by construction of roads and ponds, open pit
excavation, and disposal of waste rock should be minimal if sediment
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control methods are implemented. Surface runoff at the pit would be
collected by inward-sioping benches; sedimentation from exposed mine
areas and the waste dump fill would be controlled by a sediment collec-
tion ponds; road runoff would be directed to adequate culverts; cut and
fill slopes from road construction would be revegetated early; and
roads would be located away from streams where possible. These
measures are ideal practices which may not be consistently and fully
implemented in all cases. Furthermore, the first phases of construc-
tion, before erosion-prevention measures can be implemented, would
create areas of erosion and could cause increased sediment loading to
streams. However, once erosion-preventing practices are installed,
sediment loading to streams would be minimized.
Suspended sediment can suffocate aquatic organisms that are
adapted to clear water such as those found in Spearfish and upper
Whitewood Creeks. Increased sediment loading can also degrade the
substrate upon which macroinvertebrates live and which is used by many
cold-water fish species, such as trout, for reproduction. The sediment
settles between and on top of larger particles. This suffocates
organisms that live underneath the particles and eggs that are laid
between the particles and degrades surfaces on which stream organisms
cling and feed.
The boundaries of each of the three hypothetical sites contain one
or more streams. Potential disturbance areas of Raspberry Gulch are
within 2.4 kilometers (1.5 miles) of Spearfish Creek, which could
receive some of the increased sediment loading from Raspberry Gulch
during high-flow periods. Impacts to Raspberry Gulch could be reduced
if existing roads were used and mine operations were located on the
more level area of Dutch Flats. Sediment from the Yellow Creek site
could enter Whitewood Creek directly, or high flows could transport
sediment through Yellow Creek to Whitewood Creek, a distance of about
2.4 kilometers (1.5 miles). Potential damage to these creeks could be
reduced by using the existing roads and maintaining a buffer between
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mining operations and the drainages. Operations at the Two Bit Greek
site could affect Two Bit Creek, an intermittent stream, but would be
too far from Bear Butte Creek to affect it.
Accidental Releases
An overflow of the pregnant pond would release free cyanide and
metallic cyanide complexes. Free cyanide is much more toxic than
metallic cyanide complexes. The concentration of the free cyanide in
the spill would be 200 mg/1, but would be reduced by attenuation and
dilution to approximately 0.2, 0.02, and 0.02 mg/1 upon reaching the
mouths of Raspberry Gulch, Yellow Creek, and Two Bit Creek, respec-
tively. The levels of cyanide in these creeks would be in the range of
acute toxicity to fish. Because the cyanide would come from an acci-
dental spill and because cyanide attenuates rapidly, this source of
cyanide would not subject the aquatic community with chronic exposure
to free cyanide. Although Raspberry Gulch and Two Bit Creek are
intermittent (according to U.S. Geological Survey maps), they may be
used by fish during spring snowmelt, the conditions under which this
example was constructed. Under these conditions, significant short-
term impacts to the aquatic community of these tributary creeks would
occur. These impacts could include the loss of all fish life and much
of the macroinvertebrate life in the creek.
Because of dilution, the cyanide concentration which would occur
in Whitewood Creek due to spills in Yellow Creek would not pose a
threat to aquatic life. However, a concentration of 0.02 mg/1 of
cyanide, which was predicted for Spearfish and Boulder Creeks down-
stream from Raspberry and Two Bit Creeks, respectively could be harmful
to reproduction of fish and growth of juvenile fish. However, exposure
of fish to this level of cyanide for at least 15 days would be required
for impacts on fish reproduction or growth to occur and the spilled
cyanide would pass through the stream system within a few hours.
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One of the degradation products of cyanide Is ammonia, which in
its un-ionized form is highly toxic to forms of aquatic life. As the
cyanide degraded, ammonia concentrations in the receiving streams could
Increase. The concentrations of un-ionized ammonia could exceed toxic
levels and fish kills could result. Additional study would be required
to determine the likelihood of this impact.
The spill also contains metals complexed with cyanide (iron,
cobalt, gold, and silver) and arsenic. Aquatic toxiclty levels for
cobalt and gold have not been proposed by the EPA. If the metal
cyanide complexes released metals and free cyanide, the iron and silver
concentrations of Yellow and Two Bit Creeks would be diluted to below
toxicity levels for aquatic life. At Raspberry Gulch, however, iron
and silver concentrations would not be reduced to below chronic
toxicity levels until additional dilution was provided by Spearfish
Creek. The amount of free cyanide released from the metal cyanide
complexes would be very small since stable metal cyanide complexes
degrade very slowly (see discussion in surface water). Arsenic levels
in both Yellow and Two Bit Creeks would be below aquatic life toxicity
levels. At the Raspberry Gulch site arsenic would not be reduced to
below chronic toxicity levels until additional dilution was provided by
Spearfish Creek.
The leak from the pregnant pond liner would not produce any
impacts to aquatic biota in the area. If ground water was contaminated
and eventually discharged to surface water, the toxic substances would
be sufficiently diluted and attenuated so as to not pose any threat to
aquatic biota.
A spill from the neutralization pond during site closure could
also be a hazard to aquatic life. Chlorine Is commonly used in the
neutralization process, and both it and chlorocyanide are extremely
toxic to aquatic life. The 96-hour lethal concentration for 50 percent
of the test organisms (LC5Q) has been reported to range from 0.014 to
0.029 mg/1 residual chlorine for trout (U.S. Environmental Protection
Agency, 1976) and from 0.09 to 0.30 mg/1 for some warm water species.
Gammarus, an amphipod, exhibited reduced survival at 0.05 mg/1 residual
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chlorine and reduced reproduction at 0.0034 mg/1 residual chlorine.
Chlorine attenuates rapidly but the possibility of significant adverse
impacts to aquatic life from residual chlorine in an accidental release
from the neutralization pond exists, depending on the placement of the
neutralization pond in relation to streams.
SOCIOECONOMICS
Evaluation of impacts on the social and economic environment
differs from analysis of effects on natural systems in two major ways.
First, impacts on natural systems are almost entirely direct impacts;
that is, impacts resulting from the physical activity of the mining
operation itself. Although there are similarly direct socioeconomic
effects of mining operations, such as employment at the mine and
property taxes generated by the capital investment in the mine site,
there are also numerous indirect impacts such as employment generated
in other sectors of the local economy resulting from purchases of goods
and services by both the mine operator and by households of employees
at the mine, and sales taxes generated by these expenditures.
The second major difference between socioeconomic and natural
resource impact analyses is that most impacts to the natural environ-
ment take place (at least initially) on or in close proximity to the
site of the mine operation, while most of the socioeconoraic impacts
occur offsite. For example, employees of the mine typically live,
purchase consumer goods and services, pay taxes, and demand public
services in communities at locations distinct and separate from the
site of the mining operation. Therefore, forecasting of socioeconoraic
impacts typically requires definition of a study area covering a
broader geographic region than might be required to assess other
environmental impacts.
Project Direct Employment and Income
The driving force of many of the socioeconomic impacts generated
by a mining operation is employment at the mine. For impact assessment
purposes, it is assumed that the mining operation would have a 12-year
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life span with the first 2 years consisting of construction activity.
Employment is estimated at 35 workers the first year, 70 in the second
year and 100 employees thereafter throughout the life of the actual
raining operation. Closing of the ore producing operation would then be
followed by reclamation. It is anticipated that major reclamation
activity, employing approximately five individuals, would continue for
about 1 year after shutdown with an undetermined, low level of effort
thereafter until reclamation was complete.
Based on an estimated annual income of $25,000 per permanent
employee or mine construction worker, these employment levels would
generate personal income of $875,000 in the first year, $1.75 million
in the second year and $2.5 million in years 3 through 12 of the mine
operation. In year 13, income of $125,000 could be expected as a
result of reclamation efforts.
A basic to non-basic income multiplier of 1.6 and a basic to
non-basic employment multiplier of 2.0 is assumed for Lawrence County.
This indicates that each additional $1.00 of income in a basic indus-
trial sector such as mining will generate an additional $0.60 of income
in non-basic sectors in the county. Each additional mining job will
result in one new non-mining job, for a total of two new jobs added to
the local economy. This multiplier effect primarily results from jobs
created to satisfy the demand for goods and services generated by the
mine itself and by mine employees. Therefore, total additional employ-
ment generated during the period of full operations would be 200 jobs,
while $4 million in personal income would be added to the local economy
annually. These impacts on employment and income over the anticipated
duration of mine operations are summarized in Table 39.
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TABLE 39
ANNUAL EMPLOYMENT AND INCOME GENERATED BY
HEAP LEACH GOLD OPERATION
Years Three Year
First Year Second Year Through Twelve Thirteen
Project Direct 35 70 100 5
Employment
Secondary Employ- 35_ 70 100 _5
raent
Total Employment 70 140 200 10
Project Direct $ 875,000 $1,750,000 $2,500,000 $125,000
Income
Secondary Income 525,000 1,050,000 1,500,000 75,000
Total Annual $1,400,000 $2,800,000 $4,000,000 $200,000
Income
In addition to the impacts from mine employment and income, there
would be economic benefits resulting from mine purchases of materials,
goods, and services such as office supplies, furniture, vehicle parts,
and fuel, oil, and lubrication grease for mining equipment. After an
initial development investment in the mine, operational expenditures of
this nature are estimated at $1.2 to $2 million annually. Up to 50
percent of these recurrent purchases could be made locally, resulting
in a $600,000 to $1 million boost in sales for the local economy. The
capital investment, mineral production, and purchases generated by the
mining operations will generate property, severance, and sale tax
revenues for state and local governments (Wharf Resources, 1985).
Project-Related Population
The additional employment generated by the mine operation will
impact population levels in the county. Based on the recent experience
of other mine operators, it is expected that up to 80 percent of mine
employment will be recruited from within Lawrence County. Assuming
that this rate would also apply to additional non-mining employment
secondary to the mine operation, 160 additional jobs would be provided
for Lawrence County residents. Based on an estimated labor force par-
ticipation rate of 1.2 workers per household and an average household
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size of 2.7 persons, this would translate to 133 resident households
and 360 persons associated with the project from among the region's
current population. This increase in local employment would be ex-
pected to have some impact on stemming out-migration from the Lead-
Deadwood area.
An additional 20 percent of the jobs generated by the mine opera-
tion would be filled by in-migrants from outside the county. This
would translate to 33 households with a total population of 90 persons.
Based on residential patterns of present mine workers, about one-half
of these workers would reside in the Lead-Deadwood area., about 20
percent in Spearfish, and the remainder in outlying areas of the county
and in adjoining counties. This would result in about 17 households
and 45 persons seeking residences in Lead and Deadwood. This would
also translate to some additional demand for services provided by local
governments. The impact of these demands on local government expendi-
tures and revenues is addressed in the section on fiscal impacts.
Indirect Impacts
Employment
The direct employment impact of a gold heap leach facility will be
35 to 70 positions during project construction, increasing to 100 jobs
over the life of the mine. Because of the similarity of skills and
occupations required for the construction and operation phases of the
facility, many of the construction workers will be retained as part of
the permanent work force. Although actual leaching operations are only
anticipated to occur during a 9- to 10-month period, ceasing during the
coldest winter period, direct project employment will remain relatively
constant throughout the year. This will be accomplished through
reassignment of personnel to annual maintenance activities, preliminary
mine pit preparation, and waste dump management.
Including the indirect employment impacts, the total effect on
employment is estimated at 200 jobs. These will either be net addi-
tional employment opportunities or preservation of existing jobs.
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Based on the expected residency pattern of the project direct employ-
ment, 70 to 75 percent of the total jobs will be available within the
Lead-Deadwood local area of influence. The remainder will be distribu-
ted between the Spearfish and Sturgis areas, which provide retail trade
shopping opportunities and consumer services for their respective
market areas including the Lead-Deadwood area. Compared to total
current employment of nearly 9,000 and mining employment of approxi-
mately 1,500 to 1,600, this impact, although moderately beneficial,
will not be significant.
The project's effects on overall local employment patterns will
not vary greatly with each mine site alternative. Obviously, the
actual location of employment for the project direct employees will
vary. This will affect residency patterns and the location of a
limited portion of the indirect employment impacts. The primary shifts
in the indirect employment impacts will occur between Spearfish
assuming development at the Raspberry Gulch site and Sturgis if project
development is located at the Two Bit Creek site. The yellow Creek
site is midway between the two towns and would result in some indirect
employment gains in both towns.
Personal Income
The indirect impacts on local personal income associated with a
gold heap leach facility would parallel the impacts on employment.
Project direct wages and salaries of $875,000 would be paid during the
initial year of construction, increasing to $1.75 million the second
year. Annual direct payroll during the operating life of the project
would be $2.5 million. These estimates are based on average earnings
of $25,000 per full-time employee, reflecting current average payroll
at the Wharf Resources Annie Creek project (Mountain International Inc,
1985).
As is true in employment and population, there will be an indirect
impact on personal income resulting from the local purchases of goods
and services by the mine and employee households. The average multi-
plier for personal income is estimated at 1.6, versus the 2.0 multi-
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plier used for employment. The lower multiplier reflects the lower
average earnings in other industries, such as retail trade, compared to
mining and the expectation that some of the household consumer pur-
chases will be made outside the local economy, especially in Rapid
City, the regional trade center. Therefore, the combined annual impact
on personal income is estimated at $1.4 million and $2.75 million
during the 2 years of construction and $4 million annually over the
operating life of the mine. Following the end of operations, the local
payroll impact during reclamation will be $200,000 more than premining
conditions.
The effects of higher personal incomes will be distributed pri-
marily according to residency patterns and the distribution purchases
by the mine. Based on the experience of the Wharf Resources operation,
40 to 50 percent of the purchases are made in the Lead-Deadwood area
and 50 to 60 percent of purchases are nonlocal, primarily in Rapid
City. Measured against total wage and salary earnings of $135.7
million and total personal income of $199.4 million in Lawrence County
in 1984, these impacts would be beneficial but not significant on a
county basis. On a local basis, they would provide a welcome infusion
of additional income into the Lead-Deadwood economy which has experi-
enced a prolonged period of decline. This would be a moderately
beneficial, but not significant, impact. The magnitude, incidence, and
significance of the impacts would not vary with the alternative mine
sites except as the residency pattern varies.
Economic Base
The potential exists for both beneficial and adverse impacts on
the local economic base. The initial impacts would be positive in that
a new infusion of jobs and payroll would occur into a local economy
which has experienced lackluster performance over the past several
years. Retail and personal service establishments located in Lead and
Deadwood would benefit particuarly from the economic growth. The
anticipated operations procedure of maintaining year-round employment
would be a positive influence on an economy that currently experiences
heavy seasonal fluctuations in employment.
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Conversely, there are several downside risks involved. First, the
project would not contribute to economic diversification. Rather, it
would perpetuate the reliance on the raining industry- Although the
local mining industry has been relatively stable, other local economies
such as Butte, Montana and Leadville, Colorado have experienced sub-
stantial economic swings due to the heavy reliance on the mining
industry.
A second potential adverse impact could result from conflicts with
recreation facilities. The Raspberry Gulch site is close to two
developed downhill ski areas. Because of mineral ownership patterns
underlying the areas, there is a potential for possible interference
with the recreation use of these areas. Even without direct interfer-
ence, noise and changes in visual quality associated with heap leach
operations may have indirect impacts on the quality of recreation
experience and possibly the amount of recreation occurring. Changes in
visual quality might also affect general tourism and second home vaca-
tioners, if the operations are highly visible from the major highway
corridors. The likelihood of such impacts occurring is uncertain, and
with respect to visual awareness from highways, impacts are very
site-specific and somewhat under the control of the operator. However,
if they were to occur, they could adversely impact the region's recrea-
tion and tourism industry. The likely component of the tourism market
affected would be the regional resident who comes to the area as a
destination-type visitor or summer home occupant, not the tourists who
visit the area as part of a vacation or multi-destination itinerary.
The relative economic impacts associated with the former would be less
than an adverse impact on the latter category of tourism.
Considering both the potential beneficial and adverse impacts on
the local economic base, the development and operation of a heap leach
facility are considered moderately beneficial over the life of the
project. Impacts would not be expected to vary among site alterna-
tives.
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Population Trends
The population of Lawrence County grew 5.1 percent during the
1970's, from 17,453 in 1970 to 18,339 in 1980. During this same period
Deadwood and Lead lost population, largely because of a decline In the
mining industry. It appears likely, based on current economic condi-
tions, that In the absence of major new economic activity or a dramatic
resurgence in mining brought about by $20 to $25 per gram ($600 to $800
per troy ounce) gold prices, Lawrence County could be expected to
continue to grow at a rate close to historical levels. At this rate it
would reach a population of about 19,600 In 1990 and 20,400 in the year
2000. However, without additional new local economic activity, popula-
tion growth is not likely to occur in the Lead-Deadwood area. Economic
adjustments which have occurred there suggest a future stabilization or
slight decline In the population level.
As discussed earlier, new jobs generated by a new heap leach gold
mining operation would primarily go to existing residents of Lawrence
County. The major impact of the new jobs would be the stabilization of
the declining population In the Lead-Deadwood area. In addition, it is
anticipated that there will be a population gain to the region of 90
people resulting from In-migration to fill jobs not filled by local
residents. Fifty percent, or 45 people in 17 households, would be
expected to settle in the Lead-Deadwood area with the remainder going
to Spearfish, other areas of Lawrence County and, possibly, Sturgis.
Under all mine location alternatives the impacts on Lead and
Deadwood would be the same because both communities are located in the
center of the mining district. However, the distribution of the
remaining in-migrating population would be expected to vary among the
three site alternatives. A mine operation at the Raspberry Gulch site
would make a residential location in Spearfish relatively more attrac-
tive while a mine at the Two Bit Creek site would have good access to
Sturgis via U.S. Highway 14 ALT. If a mine was located at the Yellow
Creek site, neither Spearfish nor Sturgis would have a clear advantage
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as a residential location and the population not locating in Deadwood
or Lead would likely be more dispersed between Spearfish, unincor-
porated Lawrence County and Sturgis.
Housing
The development and operation of a gold heap leach facility in the
Lead-Deadwood area would be associated with total job creation of 200
full- and part-time positions, an associated population of 450 persons,
and a total of 167 households. However, a majority of these households
are expected to be current residents of the region who would not re-
locate. The effect of the increase in local employment opportunities
and indirect effects on the retail and services industries will be
primarily a slowing or stemming of the rate of population loss. The
net impact is projected at fewer than 20 new households requiring
housing during the operation period. The impacts during the con-
struction and reclamation periods would be even smaller.
Even though a large portion of the existing housing stock in Lead
and Deadwood is vacant, it tends to be in disrepair and unappealing to
the current market preferences. Recently, the lack of housing was
identified as one of the factors contributing to the decline in local
population as households relocate to Spearfish and/or Sturgis. How-
ever, both Lead and Deadwood have recently annexed property suitable
for residential development and are extending water and sewer services
to these areas. Also, several rural subdivisions currently exist or
are under development in the area. These include several located to
the east and south of Deer Mountain ski area; north of Raspberry Gulch
in the Dutch Flats area; south on U.S. Highway 385 along Strawberry
Ridge towards the western access route to the Galena and Anchor Hill
area; and along the Peedee Gulch road providing access to the Anchor
Hill/Dome Mountain area. Hence, the impact of the mine will be to
spawn some additional residential construction in the area. This
impact will be primarily beneficial although insignificant.
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The overall impacts on housing within the Lead-Deadwood area would
not be expected to vary greatly with the location of the project,
although the residency pattern of the work force among other communi-
ties and the amount of development in rural parts of the county may
shift with the project site. Development of mining operations in
Raspberry Gulch would increase the overall share of project employment
commuting to the Spearfish area and the amount of rural residential
development occurring south of Lead along U.S. Highway 85. Mine
development in the Yellow Creek site would result in a slightly higher
portion of employment residing in the Lead-Deadwood area and commuting
of employees to both the Sturgis and Spearfish areas. A shift in
residency patterns resulting in a higher concentration of residency
and, consequently, additional housing need in the Deadwood and Sturgis
areas would be expected if development occurs at the Two Bit Creek
site.
Development occurring at either Raspberry Gulch or Two Bit Creek
would result in mining activity within a 1- to 2-mile radius of exist-
ing concentrations of second home and year-round residential develop-
ment with the likely highway access routes passing by these areas of
development. This proximity increases opportunities for conflicts and
for noise and esthetic impacts. The Yellow Creek site is more removed
from areas of existing residential development and its access roads
already carry considerable truck traffic associated with the operations
of the public dump sites located in the Yellow Creek area. On a
relative basis, Raspberry Creek possesses the highest likelihood of
adverse impact. The impacts associated with Two Bit Creek are lower
and Yellow Creek site has the least likelihood of adverse impacts on
existing residential development.
Community Services and Infrastructures
Schools. The Lead-Deadwood School District No. 40-1 serves Lead,
Deadwood, and the surrounding unincorporated area. Since consolidation
of the district in 1972 there has been a steady decline in enrollment
and the district facilities now being utilized could accommodate up to
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200 additional students without significant impact on district opera-
tions. Depending upon the number of students added, additional teach-
ing staff could, of course, be required. Based on added population to
the area from the mining operation, it is anticipated that between 10
and 20 students would be added to the school district enrollment. This
increase could be accommodated with a minimal or negligible increase in
staff and facilities. This impact would not vary by mine site alterna-
tive. Increased assessed valuation resulting from mine development at
any of the three locations would be within the school district bound-
aries.
Law Enforcement and Fire Protection. Law enforcement and fire
protection is provided locally by a series of agencies working together
in a cooperative framework which maximizes the level of protection
afforded given limited human and physical resources. While each agency
has its own primary jurisdiction and responsibilities, there are a
number of formal and informal arrangements in place to supplement the
individual capacities of any single agency. For example, the Deadwood
Fire Department has an aerial/ladder fire truck which can be used to
suppress fires in multistory structures. The Lead Fire Department does
not have such equipment, but can call upon the Deadwood Fire Department
if needed under a mutual assistance pact.
At present, the local fire protection services are adequate and
are in the process of being upgraded. Therefore, there would be no
appreciable impacts associated with the project.
The primary law enforcement agency serving the region is the
Lawrence County Sheriff's Department. In addition to patrol and
investigation duties throughout the county, the sheriff's department
handles communication and dispatch services for all law enforcement and
emergency services throughout the county as well as detention facili-
ties. Additional staffing is desired at the current time, but the
needs are not critical and the quality of law enforcement afforded is
not affected. Additional law enforcement assistance in the area is
provided by the South Dakota Highway Patrol offices stationed in Dead-
wood.
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Both of the municipal police departments in the area have existing
needs. The Deadwood Police Department needs additional staff, updated
patrol vehicles, and additional office space. The Lead Police Depart-
ment is in need of improved office space.
The limited population associated with a heap leach facility would
not generate significant impacts on local law enforcement agencies.
Some additional traffic enforcement and motor vehicle accident investi-
gations will occur as traffic volumes increase. The incidence of these
impacts may shift depending on the location of the mine site, as
different access routes involve various combinations of Federal, State
and local roads. However, the significance of impacts would be un-
changed.
Medical Care. As indicated previously, a new mine would slightly
increase population levels, by less than 50 persons, in the Lead-
Deadwood area. Based on the current population of about 6,000 in these
two municipalities, and the current occupancy level of 40 percent at
the Northern Hills General Hospital, there would not be any demand
placed on local health care facilities and services which could not be
met. In fact, the stabilization and slight increase in population
which would occur might help to assure that the current level of health
care services would continue to be provided in the Lead-Deadwood area.
The impact on health care facilities in other communities such as
Spearfish and Sturgis would be minimal as even fewer individuals would
be involved and the facilities available in these larger communities
are generally more extensive. The impacts would follow the same
patterns as population and would vary slightly among the three sites,
but would not be expected to strain the capacity of health care de-
livery systems.
Solid Waste. Regular residential and commercial garbage and trash
collection in the city of Lead is handled by a private contractor.
Solid wastes are hauled to sanitary landfills near Belle Fourche or
Sturgis. Deadwood garbage collection is handled by the municipality
and the waste is hauled to Belle Fourche or Sturgis. Deadwood is
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currently considering shifting its garbage collection to a private
contractor. The facility at Belle Fourche, which is currently used by
the major contractor in the area, has an estimated 50-year life. The
small additional population moving into the area as a result of the
mine operation would not be expected to produce sufficient additional
waste to impact the lifespan of that facility (K. Petersen, Belle
Fourche Sanitary Landfill, personal communication, 1986).
The only other solid waste facilities in the area are a series of
separate dump pits south of Lead operated by Lead-Deadwood, the Home-
stake Mining Company, and the Black Hills Power and Light Company.
Only the Lead-Deadwood facility would potentially be impacted by the
mine development. This facility is open to the public on a fee basis
but dumping is limited to metals and burnables. It receives limited
use by the cities, including Lead's annual spring trash pickup. The
facility has an estimated remaining life of 13 years but this may be
extended by expansion and improved management techniques such as
compaction and selling off salvageable metals. It is not expected that
the population growth attributable to the mine operation would affect
the lifespan of this facility.
No hazardous materials resulting from the mine operation would be
disposed at the area dump or sanitary landfill facilities. Hazardous
materials would be handled by the mine operators or by private contrac-
tors as is the practice at current mine operations.
The impact of mine development on local solid waste facilities and
operations would be negligible. The major share of this activity is
handled by private contractors and the additional volume would be
insignificant relative to overall solid waste now produced in the area.
The level or nature of the impact would not vary by the mine location
alternative.
Water and Wastewater. The domestic water supply for the communi-
ties of Lead and Deadwood is obtained from water resources developed by
the Homestake Mining Company. Total capacity of the system is 30,800
cubic meters (8.15 million gallons) per day. Peak demand is currently
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28,000 cubic meters (7.4 million gallons) per day. The water demand
generated by the 17 additional families expected to move into Lead and
Deadwood as a result of mine development would not be likely to exceed
23 cubic meters (6,000 gallons) per day and could easily be accommo-
dated by the existing water system. Both communities also have ade-
quate storage and delivery systems and are able to provide sufficient
volume and pressure for firefighting purposes. No impact is foreseen
on this capability.
Sanitary sewer and wastewater treatment for a population of 7,000
to 8,000 people in Lead, Deadwood, Central City; and a small unincor-
porated area is provided by the Lead-Deadwood Sanitary District No. 1.
The district operates an activated sludge treatment facility built in
1979 with a capacity of 8,820 cubic meters (2.33 million gallons) per
day. This capacity is seldom exceeded except during periods of heavy
rain, when Lead's storm runoff flows into the sanitary treatment system
resulting in total flows of as much as 30,000 cubic meters (7 million
gallons) per day. During periods when storm runoff is not a problem,
the system operates at a peak demand of about 8,700 cubic meters (2.3
million gallons) per day, which is near capacity. Therefore, any major
additions to the population base in the district could require that
wastewater treatment facilities be expanded. The 17 families added to
the area by mine development would contribute up to 17 cubic meters
(4,500 gallons) per day to the wastewater flow. Although this addi-
tional flow would contribute to a potential need for expanded facili-
ties it is unlikely that this population increment would by itself
require Sanitary District No. 1 to increase its wastewater treatment
capacity.
County Roads. Heap leach gold mining operations would involve
onsite processing of the ore. Therefore, frequent heavy equipment
travel over roads to and from the site would be limited to the con-
struction phase of the mine and would largely depend on the need for
materials from offsite sources. After the construction of mine facili-
ties was completed and actual mine operations were underway, trans-
portation impacts would consist primarily of mine employees commuting
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to and from the facility. Some heavy truck traffic associated with the
delivery of fuel and chemicals would occur. However, the volume of
such traffic is expected to be low.
Impacts of the project on roads in the Lead-Deadwood area would
primarily affect the county road and bridge department, but would vary
depending upon where development took place. In some instances, roads
have recently been upgraded and would require little additional atten-
tion. In other cases, roads are currently identified as needing im-
provement and this need would become more immediate if mining activity
were to occur. Other roads are adequate for current use but would
require improvements to handle the increased volume and intensity of
use caused by a mine operation. Virtually all potential mine sites
would impact some county maintained roads and road segments. In
addition to potential improvements, increased maintenance and snow
clearing efforts would also be required as a result of the operations.
As has occurred in the past, it is anticipated that necessary road
improvements would be a cooperative venture among the county, the U.S.
Forest Service, the Bureau of Land Management and the mining company.
As necessary, cooperative agreements could be negotiated as part of the
extractive industry special use permitting process being developed by
Lawrence County. The greatest impact on county roads would result if
development occurred at the Yellow Creek site because this area is
primarily served by county level roads. The Raspberry Gulch site and
the Two Bit Creek site are close to major State-maintained highways
which would bear most of the traffic load if development occurred in
those areas.
General Government. As a result of declining populations in Lead
and Deadwood there have been cutbacks in the overall level of local
government administrative staff in Lawrence County over the past
several years. At the same time, older buildings housing government
offices have deteriorated to the point where they can no longer be used
or are in need of renovation. As a result, the municipalities of Lead
and Deadwood and the county are all developing plans to remedy the
space shortages for governmental administration. Mine development
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could place additional demands on local governments requiring some
additional staff and could contribute to the existing office space
shortage. However, the additional needs attributable to mine develop-
ment would be minor relative to existing needs. This impact is not
considered to be significant and would not be expected to vary by mine
site alternative.
Fiscal Resources
A gold heap leach project would have both beneficial and adverse
impacts on local fiscal resources. Beneficial impacts would accrue in
the form of additional property taxes to the county and school district
and additional sales tax receipts to the municipal budgets of Lead and
Deadwood. Based on information supplied by Wharf Resources, the
property tax payments to the county will total less than $20,000
annually due to the relatively low capital investment associated with
heap leach operations. Increased annual sales tax receipts to all
local communities would be between $10,000 and $20,000. Sales,
severance, and corporate net profits taxes would also accrue to the
State. Indirect tax revenues would accrue to these same entities based
on property tax collections on residential and commercial development
and sales taxes on household expenditures. There is no personal income
tax in South Dakota.
There would also be negative fiscal impacts of mine development.
These impacts would result from the need to provide services to a
larger service-area population and commercial/Industrial base. The
Lawrence County Highway, Planning, and Sheriff's Departments would
experience the greatest impacts, especially the first two of these
agencies. The highway department would experience increased needs for
road maintenance and possibly snowplowing operations to provide year-
round access.
The increased demands on the planning department will be in the
form of increased staff effort associated with the issuance of a
conditional use permit and monitoring of project operations with
respect to that permit. Because the department presently has only a
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single full-time professional and half-time secretarial assistance to
cover the entire county, any increase in the workload would constitute
an adverse impact.
The mine would increase demands on the sheriff's department for
general law enforcement activities, especially traffic enforcment and
accident investigation. These impacts would translate into needs for
additional staff and expenditures. However, in light of the substan-
tial volumes of resident and tourist traffic presently occurring in
the area and the extensive highway network currently patrolled by the
department, the incremental impacts would be minimal.
Additional demands for public services would be generated by the
project-related household and population impacts. All public service
agencies would be affected. However, many of these services, such as
the school system and hospital, have excess capacity available to
accommodate the growth. Other public service providers such as the
Lead-Deadwood Sanitary District No. 1 already have existing needs. The
limited additional growth will increase the needs, but not be solely
responsible for any system reaching a threshold that requires expansion
of capacity and major capital investment. These agencies will receive
limited additional revenues from their traditional revenue sources, be
they fees for services rendered or property taxes.
A lack of quantitative projections of project-related impacts on
public revenues and expenditures by jurisdiction and agency prevents a
quantitative determination of net fiscal impacts. However, the primary
revenue flows will accrue to the State, with successively lower reve-
nues accruing to the county, municipalities, and service providers.
The increased demands for services will, however, be widely distributed
across numerous separate service providers. The overall net impact
will be an insignificant adverse impact. The magnitude, incidence, and
significance of impacts would not vary by the location of the mine
among the alternative sites.
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Recreation Resources
The Black Hills National Forest is a major recreation area of the
State and provides opportunities for camping, boating, hiking, hunting,
fishing, downhill and cross-country skiing, and snowmobiling. Develop-
ed recreation sites in the immediate Lead-Deadwood area include the
Hanna Campground and the Deer Mountain and Terry Peak ski areas. Most
of the dispersed recreation activity such as stream fishing and hiking
occurs on public lands managed by the U.S. Forest Service (Figure 21).
The impact of a gold heap-leach facility on recreation can be
evaluated in terms of the amount of recreation activity displaced by
mining operations and the potential for indirect impacts on the overall
recreation experience such as noise, traffic or visual/esthetic changes
associated with the project. With respect to the potential impacts on
recreation from heap leaching operations in the northern Black Hills,
they are best considered on a site-specific basis.
Across all of the alternative sites, those impacts on recreation
resulting from direct loss or interference with a developed recreation
facility would be expected to be long-term, as would most of the
indirect impacts on the recreation experience associated with esthetic
changes. Indirect impacts associated with project operations, such as
noise and traffic, would continue over the life of the project.
Raspberry Gulch. The potential for significant adverse impacts
among the alternative sites is greatest at this location. It is
located southwest of the only two developed downhill ski areas in the
entire Black Hills area. The combined annual activity of these two
areas is between 100,000 and 120,000 skiing-visits.
As described, the mining area would not involve direct interfer-
ence with the ski area operations through use of any of the lands
involved. Adverse effects on the recreation experience for skiers
could potentially occur as a result of equipment noise, blasting of the
ore deposits, or affects on esthetics. The latter would occur as a
result of the contrasts between the existing heavily forested hills and
the exposed soils and rock in the mine and work pits, as well as the
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FIGURE 21
TOURISM ROUTES AND
RECREATION SITES
HYPOTHETICAL MINING
OPERATIONS SITES
PRIMARY TOURISM
ROUTES IN THE REGION
PRIVATE AND PUBLIC
DEVELOPED RECREATION
SITES
SCALE
O1 2346
-t V^s
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well-defined linear outlines of the heap piles. Because the lifts and
runs for the ski areas face an arc of 210 degrees from due west to
southeast, the potential for impacts is somewhat lower at the Raspberry
Gulch site than would occur if the relative location of the mine were
to be in any of the other three geographic quadrants surrounding the
ski areas. For example, the existing heap pile for the Wharf Resources
project is visible from the top of the Terry Peak chair lift.
The potential for other direct and indirect impacts on dispersed
recreation are also quite high at this site. It is located just south
of a vacation home development on Dutch Flats and immediately north of
several clusters of recreation cabins located along Spearfish Creek
near Cheyenne Crossing. Spearfish Creek is rated as having the best
fishing in the area, although a stocking program is presently used to
maintain the fish population and fishing quality in Spearfish Creek.
While the total amount of recreation and leisure activity occurring in
the area is not available, and no adverse effect on aquatic life is
expected, the potential exists for adverse effects from mine develop-
ment on the quality of the fishing experience.
With respect to impacts on esthetic qualities for tourists in the
area, the most likely vantage point would be from Cheyenne Crossing to
the south. However, Cheyenne Crossing is located at the confluence of
the east and west forks of Spearfish Creek and is characterized by
narrow canyons with limited fields of visibility. Therefore, these
impacts would be limited. Overall, however, locating gold heap leach
operations at the Raspberry Gulch site could result in potentially
significant adverse impacts on recreation.
Yellow Creek. The potential for recreation impacts is limited at
this site. The site is located in an area that receives little current
recreation use, is close to a number of public dump sites, has heavy
truck traffic already occurring, has no developed recreation sites,
does not currently have and is not expected to support substantial
permanent or seasonal residential development, and is not highly
visible from major tourism routes or developed recreation sites.
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Therefore, there will be essentially no impact on recreation from mine
development at the Yellow Creek site.
Two Bit Creek. Potential recreation impacts in this area would
only affect dispersed recreation as there are no developed recreation
sites in the area. The land is a combination of private mining claims
and public lands managed by the U.S. Forest Service. According to the
forest service's local recreation planner, the area does not receive
significant use, primarily because it is not particularly scenic
relative to other nearby areas and the fish and wildlife populations
are limited.
The primary activities currently occurring in the area are fish-
ing, hunting, hiking and 4-wheel driving on the old logging and mining
roads. The site comprises a portion of an elk habitat area located
southeast of Deadwood. However, because the elk herd is small, 30 to
50 animals, no elk hunting is currently allowed in the area.
The Two Bit Creek site is located within a 3-kilometer (2-mile)
radius of both seasonal and permanent residential developments. Thus,
additional private recreation may be occurring in the area. Overall,
mine development at this site could result in limited adverse impacts
on recreation, but they would not be significant.
Lifestyles and Attitudes
Development of heap-leach mining facilities in the Lead-Deadwood
area would reinforce historical-traditional lifestyles in the area.
Since the area's initial settlement by prospectors during the Gold Rush
of 1874 to 1876, mining has been the predominant force behind the
county's economy. In spite of recent declines in both the nation's and
the local area's mining industries, mining still accounts for 18
percent of total county employment and nearly 40 percent of total local
wage and salary earnings.
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The example mine would provide additional employment opportunities
for existing unemployed members of the labor force and future entrants
into the labor force who might otherwise leave the area. A small
influx of new resients is expected to fill key management and technical
positions and to fill any voids not satisfied by the local labor force.
These new residents would share a lifestyle similar to the existing
permanent residents of the area.
To the extent that a gold heap leach facility creates conflicts of
lifestyle, it is likely to affect a limited number of seasonal summer
home residents, owners/residents of permanent year-round homes, and the
operators of the two ski areas. All of these developments are located
in close proximity to the areas of active exploration and development
or along the primary access routes to those same areas. In many
instances, the owners of the residences or recreation facilities do not
own the mineral rights underlying the property, or in some cases, do
not even own the surface rights, but occupy the land under property
lease arrangements. In either case, these owners knowingly entered
into an arrangement where the potential for mineral extraction has long
been established. The fact that these rights have not been exercised
previously must, to a great extent, be viewed as a windfall to those
residents, not as a basis for prohibiting mining or for seeking undue
compensation. In instances where permanent or seasonal home property
owners own both mineral and surface rights, a legitimate lifestyle
conflict may arise between the rights of all parties to have access and
use of their properties in whatever manner they choose, as long as it
complies with local land use ordinances and does not endanger the
public health, safety, and welfare.
In any case, the numbers of individuals affected is small in
comparison to the economic benefits to the community as a whole.
Furthermore, there are means available to minimize the potential
conflicts associated with mining activity occurring in close proximity
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to other existing land uses. These could include a negotiated agree-
ment between property owners specifying reduced operating speeds for
company-owned and employee vehicles in the proximity of residences to
reduce noise and dust<,
Overall, the issue of lifestyle conflicts reduces itself to
weighing economic livelihood benefits accruing to numerous households
and the community-at-large against the rights of individual property
owners. Although there are definite negative impacts associated with
mine development, the strong historical role of mining in the communi-
ty, the well established record of mineral rights ownership, and the
economic benefits associated with the project would effectively out-
weigh the adverse impacts resulting in an overall net beneficial impact
on lifestyle.
Impacts on lifestyle will definitely vary on a site-specific
basis. Because of the existing level of residential and recreational
development around Raspberry Gulch, the general conclusion of net
beneficial impacts would change to an insignificant adverse impact.
The general assessment of beneficial impacts would apply to both the
Yellow Creek and Two Bit Greek sites.
Cumulative Impacts
If two or more new mining operations are developed in the area,
cumulative impacts could not be estimated by simply multiplying the
impacts described here for one mine by the total number of new mine
operations. The impacts from two or more mine operations developing
simultaneously could be much different than additive analyses would
indicate. For example, the driving force of most socioeconomic impacts
is employment, both at the mine and resulting as a secondary impact of
the mine operation. For a single mine operation, 80 percent of the new
jobs could probably be filled by Lawrence County residents. This would
result in a relatively small in-migration to the county and the
Lead-Deadwood area. However, for employment generated by a second or
third new mine operation simultaneously opening in the county, the
percent of jobs which could be filled by local residents would decline.
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This would result in more in-migration and proportionately greater
impacts on everything from schools to wastewater treatment. Thus, the
impact from a number of heap leach gold processing operations in
Lawrence County would be very different from the impacts portrayed in
this analysis, and further evaluation would be required to assess the
cumulative impacts of multiple new operations in the county.
SUMMARY OF PROJECTED IMPACTS
The potential effects of an open pit mine and cyanide leaching
operation in any of the three drainages selected for study are summa-
rized in Table 40. All of these impacts are based on the hypothetical
mine described in Chapter 4, including the example cyanide spill and
leak situations. Except for socioeconomic impacts, the significance of
the impacts did not depend on the drainage in which the operation was
located. The table lists resources affected by any cyanide leaching
facility in the Black Hills. The expected duration and significance of
effects are assessed for specific individual activities which consti-
tute the operation. Although this evaluation is specific to the sites
and hypothetical facility discussed in preceding sections, the table
can be modified to illustrate the projected impacts from actual pro-
posed projects which may have their own unique effects.
The environmental and socioeconomic effects of an open pit mine
and cyanide heap leach operation vary, depending on the location of the
facility, the areal extent of disturbance, and the configuration of the
mine facilities. The impacts to soils, vegetation, and wildlife are
primarily a function of the location of the project, the size of the
area disturbed, and the amount and success of post-raining reclamation.
The impacts to surface and ground water and to aquatic life are a
function of the distance of the operation from streams or regional
aquifers. The proximity to critical wildlife habitat is also an
important factor in influencing impacts to wildlife species. Socio-
economic effects depend on the distance of the operation from developed
recreation areas and population centers. Site-specific baseline
investigations and impact assessment are necessary to determine more
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TABLE 40
SUMMARY OF IMPACTS FOR CYANIDE
HEAP LEACHING IN THE BLACK HILLS
(EFFECT/DURATION/SIGNIFICANCE)
Mine
Pit
Physical Resources
Ground water -/P/I
Surface water -/C/I->M
Soils -/L/I
Biological Resources
Vegetation -/L/I-»M
Wildlife -/L/I-»S
Aquatic Life -/C/I-»M
1X3
£ Socioeconomic Resources
Population (Growth) +/P/I
Services/Utilities -/P/I
Employment
Opportunities +/P/M
Recreation -/L/M-»S
Housing +/L/I
Effect + = positive effect
- = negative effect
0 = no change
Duration L = Long-term (12 years
P = Project Life (3 - 12
Waste Rock
Disposal
0
-/L/I->M
-/P/I
-/P/I-»M
-/P/I-^S
-/L/I-»M
+/P/I
-/P/I
+/P/M
-/L/M-»S
+/L/I
to beyond
years)
C = Short-term (construction phase
Significance S = Significant
Roads
0
-/c/i
-/P/I
-/P/I-»M
-/P/I->S
-/c/i
+/P/I
-/P/I
-/P/M
-/L/M-»S
+/L/I
project life)
or 1-2 years)
Crushing
Facility
0
-/P/I
-/P/I
-/P/I-»M
-/P/I->S
-/P/I
+/P/I
-/P/M
+/P/M
-/L/M-»S
+/L/I
Heap-Leach
Process
Area
-/P/I
-/P/I
-/P/I
-/P/I-»M
-/P/I— >S
-/P/I
+/P/I
-/P/I
+/P/M
-/L/M-^S
+/L/I
Accidental
Leaks
-/L/I-»S
-/C/I
-/C/I
0
0
-/C/I
0
0
0
0
0
Accidental
Spills
-/c/i
-/C/I->S
-/c/i
-/c/i
-/C/I->M
-/C/I-»S
0
0
0
-/C/M-»S
0
M = Moderate
I = Insignificant
= Indicates potential range of Impact significance which would depend on specific characteristics and location
of mine development.
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accurately the significance of potential impacts. Therefore, where
site-specific information is not available for the hypothetical mine
example, a range of anticipated significance is provided in Table 40.
Mass-wasting of the disturbed areas, particularly at the mine pit,
can be prevented by adequate slope stabilization techniques. Other
impacts to geological resources are not anticipated.
Effects on ground water quality may occur In conjunction with
pumping drawdown from wells used to provide water to the mining and ore
processing operations. If the presence of shallow aquifers requires
mine pit dewatering, some lowering of the water table and possible
changes in ground water quality may also occur. These Impacts, al-
though negative, would be insignificant over the life of the project.
No long-term ground water quality changes are anticipated from general
mining operations since sulfide ore would not be disturbed. An acci-
dental leak of process solution could have potentially significant,
long-term Impacts to ground water quality If the water table (such as
an alluvial aquifer) was near the surface. If the depth to water is
greater, as in the case with the hypothetical mine, the impact on
ground water quality may be minimal. Impacts to ground water quality
from a process pond overflow could be insignificant because of attenu-
ation of cyanide and limited Infiltration.
Impacts to surface water resources caused by increased sedimenta-
tion from the general mine operations would occur primarily during the
construction phase. These impacts could vary from insignificant to
moderate, depending on the proximity to a major stream and on the
sediment control structures provided. Runoff from mine facilities and
roads over the life of the project would have minimal effect on water
quality if runoff control structures are installed and maintained. A
moderate increase in sedimentation from erosion of the waste rock piles
could continue beyond the project life if the pile is located in a
drainage. A leak in the pond as described in the example is expected
to have a minimal or even undetectable effect on surface water quality.
However, if the distance between a spill and the ground water discharge
point was small, the impact to the receiving stream could be moderate.
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A process solution spill would have a short-terra effect ranging from
significant on a stream adjacent to the facility to insignificant in
downstream reaches because of dilution and attenuation.
Soils would be removed and compacted during construction and
operation of the mine facility. For some areas at the site, the
effects would be temporary and stockpiled soil would be redistributed
during reclamation. However, in the case of the mine pit, which is not
scheduled for reclamation at the end of the project, this effect would
extend beyond the life of the project. Accidental releases of cyanide
solutions would have short-terra, insignificant impacts on soils because
potentially toxic solution constituents would be transformed to harm-
less or inert forms.
Vegetation resources would be removed or disturbed during the
construction phase. The resource would be restored in some areas of
the site during reclamation. However, in other areas, such as the mine
pit, reclamation would not occur for some time, causing a long-term
vegetation loss in these areas. The significance of these losses to
vegetation depends on the specific types of communities disturbed. A
spill would have short-term but insignificant effects on the plant
community because of cyanide attenuation and dilution and the low
inherent toxicity of cyanide to plants. Leaks are not expected to
affect vegetation resources.
Wildlife would primarily be affected by habitat losses and degra-
dation and increases in wildlife-human confrontations. The signifi-
cance of the effects depends on the wildlife present under preproject
conditions, the availability outside of the disturbed area of the
habitat lost or degraded, the extent of the habitat loss or degrada-
tion, and the intensity of the human encounters. Disturbance of winter
habitat or other specialized areas could have a significant effect on
wildlife populations critically dependent on such habitats. Most
effects would continue through the life of the project until habitat
was restored during reclamation. Some long-term impacts would be
experienced in areas that are not immediately revegetated, such as the
mine pit. Only minor impacts from road kills and poaching would be
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expected from the mining operation. Generally, no Impacts to wildlife
are expected from a process solution leak because the leaked solutions
would not be available to wildlife species. If the leaked solutions
were eventually discharged to surface waters, toxic substances would be
sufficiently diluted or attenuated so that wildlife poisonings would
not occur. Some direct mortality could occur during a pond spill if
animals were to drink the process solution before dilution or attenu-
ation of the toxic components could occur. This type of direct mor-
tality could also occur if animals were to gain access to the process-
ing facility and drink process water. These impacts would be Insig-
nificant to moderate, depending on the numbers and kinds of animals
near the site and the concentration of the solution components.
Impacts to aquatic life could result from Increased erosion and
contamination of surface waters. Some increased sedimentation could
occur, particularly during construction. These impacts would be
insignificant if adequate sediment control structures are used. In the
waste rock disposal area, effects from erosion and sedimentation could
be moderate and long-term if the pile Is placed in a drainage. Impacts
resulting from a process solution leak would be insignificant. Impacts
from a pond spill could be significant in the first stream areas en-
countered. In these reaches, cyanide and metal concentrations could
exceed acute toxicity levels. Most Impacts, however, would be short-
terra because of rapid cyanide attenuation and dilution. Metals,
although diluted to below toxic levels, would probably remain in river
sediments for some time.
Many of the socioeconomic impacts of a heap leach operation would
be similar regardless of the location of the mining operation. There
would be moderate beneficial effects on employment, income, and the
economic base during the life of the project. This would be accom-
panied by positive but insignificant impacts in population and per-
manent housing In nearby towns. The expected additions to the housing
stock would be a long-term benefit continuing past the life of the
mine. There would be an insignificant positive impact on schools, no
impact on fire protection or solid waste disposal, and an Insignificant
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negative impact on law enforcement, water and sewer, and county roads.
The need for additional services is expected to result in a negative
but insignificant impact on local government budgets. Local govern-
ments would bear almost all of the additional costs associated with
required public services whereas public revenues generated by the
mining operation would be shared by the State, the county, and cities.
These revenues would generally be spread over a broader geographic area
than would the demands for services.
Site-specific characteristics would affect the significance of
impacts to recreation and seasonal housing. Impacts could be more
severe at the Raspberry Gulch site because of its proximity to recrea-
tional areas. At the Two Bit Greek site, the impacts would be less
severe with no impact on developed recreation, a negative but insignif-
icant impact on dispersed recreation, and adverse impacts ranging from
insignificant to moderate on seasonal housing. There would be virtual-
ly no impact on either dispersed or developed recreation at the Yellow
Greek site and an insignificant negative impact on seasonal homes.
The impact of a heap leach operation on lifestyles in the region
would also vary among sites, based on the specific location and charac-
teristics of a mining operation. The moderate positive effects on
employment opportunities, income, and the economy in general are
expected to outweigh the generally insignificant negative impacts on
fiscal conditions, recreation, and seasonal homes at the Two Bit Creek
and Yellow Creek sites. However, the potential for long-term moderate
adverse impacts on dispersed recreation and seasonal homes, and poten-
tially severe impacts on developed recreation, could outweigh the
shorter-term economic gains if development occurred at the Raspberry
Gulch site.
A detailed site-specific analysis would be necessary to refine
this impact analysis according to actual facility location, size, and
configuration. In addition, development of more than one mine opera-
tion could result in cumulative impacts to the area. It would not be
appropriate to assume that cumulative impacts could be estimated by
simply multiplying the impacts described for one operation. The
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impacts from two or more mine operations developing simultaneously
could be quite different, particularly for resources that are affected
by factors other than the actual disturbed acreage.
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CHAPTER 5
OPTIONS FOR MITIGATION
A number of options are available to prevent or mitigate impacts
from heap leach mining facilities. Mitigating actions are most comonly
implemented to comply with Federal, State, or local regulations, but in
some cases are initiated by the raining company to protect unique
resources or address unusual conditions at the mine site. General
activities to prevent or mitigate adverse impacts at many mine sites
are discussed in this chapter. The intent of this chapter is not to
present an exhaustive list of available options, but rather to illus-
trate measures that could be used at future heap leach mining activi-
ties. All options would not necessarily be applicable to every opera-
tion.
MITIGATION OF POTENTIAL GEOLOGIC IMPACTS
The potential for mass failures can be reduced or eliminated by
proper siting and engineering. Pit wall failure can be minimized by
reducing slopes, increasing the bench width, and revegetating. Impacts
resulting from alterations to topography can be reduced by recontouring
to blend with natural topography during reclamation.
MITIGATION OF POTENTIAL GROUND WATER IMPACTS
Impacts to ground water resources at heap leach sites may result
from accidental releases of cyanide, which can introduce cyanide and
dissolved metals Into the ground water system, or from lowering the
ground water level, either through pit dewatering or by using ground
water as a source of water at the heap leach mine site. Shallow
aquifers generally have a greater potential for sustaining impacts to
both water quality and quantity than deeper aquifers. The following
measures can be implemented to prevent or reduce impacts to ground
water at heap leach sites.
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Minimize use of ground water sources and use recycling;
evaluate potential effects on surrounding ground water users.
Locate facilities that have the potential for leaking, such
as the plant, ponds, and pads, on sites where the ground
water is not near the surface where possible.
. Construct and maintain pond and pad liners adequately to
prevent leaks and install leak detection systems for pond
liners to contain process solution if it has leaked.
Construct underdrains beneath facilities to intercept leaks
before they enter the ground water.
Rinse and neutralize the spent ore adequately (as determined
by regulations) to minimize the potential for the leaching of
cyanide by precipitation and its subsequent entry into the
ground water system by seepage. This measure is especially
important if spent ore is removed from the pad and placed on
the ground without a pad.
Install a network of monitoring wells to assess possible
downgradient impacts to ground water.
MITIGATION OF POTENTIAL IMPACTS TO SURFACE WATER AND AQUATIC BIOTA
Cyanide heap leach operations can affect surface water and aquatic
life through increased sedimentation, and degraded chemical quality.
Sites located along a major stream will have a greater potential for
increasing stream sediment loads through runoff and erosion than sites
located at some distance from waterways. This is particularly true if
certain components of the operation such as waste rock piles are placed
in side drainages. There are, however, a number of structural mitiga-
tion measures that can reduce the amount of sediment entering the
stream.
241
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Construct culverts, water bars, sediment traps, sediment
basins, rip-rap, contour interceptor ditches, and return
systems for runoff control to reduce erosion from roads and
disturbed areas, and route unpolluted waters around disturbed
areas.
Minimize the extent of disturbance, revegetate as soon as
feasible, and protect bare soil surfaces to reduce erosion.
Limit the use of heavy equipment in natural drainages and
repair damage to inhibit water erosion.
Limit the width of haul roads to single-lane access to reduce
erosion and associated sedimentation.
Design outslopes of ponds so that they are not readily
susceptible to erosion.
Install vegetation buffer strips to reduce both wind and
water erosion.
The effect of a spill would be more pronounced in surface water
systems than in ground water systems because there would be less op-
portunity for cyanide attenuation. Spills occurring at greater dis-
tances from surface waters could be partially or completely detoxified
by natural process such as volitization, adsorption onto soil parti-
cles, or the actions of microorganisms or plants. The following
mitigation measures may be employed to reduce impacts from leaks or
spills.
Install pond and pad liners with leak detection systems, as
discussed in ground water mitigation.
Avoid constructing pads or ponds irameidately adjacent to
drainages.
Treat poor quality water before discharging it to surface or
subsurface water systems.
242
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Prevent the release of chemical solutions through ditching
and berming of the leach pad, processing plant, ponds, and
cyanide storage areas.
Design an emergency spill control plan and maintain a supply
of chemicals to treat spilled solution.
Design the pond system capacity to be capable of containing
significant storm events in order to reduce the likelihood of
a spill or breech.
Provide auxiliary power to maintain proper pond levels during
main power failures.
Re-establish the fish community, if necessary, by appropriate
measures such as stocking following accidental spills.
MITIGATION OF POTENTIAL IMPACTS TO SOILS AND VEGETATION
Surface disturbances from the mine, materials stockpiles, and ore
procesing facilities are the major factor affecting soils and vegeta-
tion. Surface disturbance should be minimized and sensitive or unique
areas (such as wetlands, populations of rare, threatened, or endangered
plant species, and riparian areas) should be avoided. In areas that
must be disturbed, most mitigation measures Involve either initial site
work or post-disturbance reclamation and include the following.
Minimize soil compaction to the extent possible.
Stockpile toposils separately from all other stockpiled
materials.
Ensure that best-management practices are utilized to protect
stockpiled soils and disturbed areas from wind and water
erosion through the life of the project and during reclama-
tion.
Test disturbed soils for necessary soil amendments prior to
revegetation.
243
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Slope all regraded areas to promote controlled drainage and
limit erosion.
Use appropriate plant species mixtures to revegetate disturb-
ed areas.
In addition, if areas are recontoured during reclamation, visual
esthetics are improved. Other practices to mitigate impacts from
surface disturbance include enchancing offsite vegetation types, and
increasing employee awareness of forest-fire and prairie-fire preven-
tion.
MITIGATION OF POTENTIAL IMPACTS TO WILDLIFE
Impacts to wildlife result mainly from habitat degradation and
destruction, and from increased confrontation between humans and
wildlife. Impacts to wildlife can be reduced by avoiding sensitive or
unique areas such as elk calving grounds, winter habitat, movement
corridors of big game, raptor nest sites, and riparian and wetland
areas. It may be possible that alternative habitats can be enhanced to
offset losses of habitat removal and degradation. Habitat losses can
be minimized by reducing the size of the facilities to the extent
possible, while maintaining facility effectiveness and function.
Site-specific Investigations to avoid locating facilities in Important
wildlife habitats can also reduce losses.
Confrontations between humans and wildlife result from the proxim-
ity of humans to wildlife, increased noise, and traffic. Road kills,
wildlife disturbance, and poaching can be reduced through the following
measures.
Route roads and locate mine faciliteis around or away from
important/sensitive wildlife use areas and habitat.
Minimize lengths and widths of roads.
Arrange work schedules and use mass transit or car pools to
reduce the amount of traffic.
244
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Conduct operations only to during daytime hours to reduce
nighttime traffic and road kills.
Reduce speed limits and post caution signs in heavily used
game areas.
Minimize the number and degree of curves and hills on new
roads.
Ban firearms on the project site.
Establish employee penalties for wildlife law violations.
Poisoning or contamination of wildlife are secondary project
concerns. By controlling wildlife access on the site, incidents of
wildlife poisoning can be decreased. Adequate fencing of processing
areas and netting or flagging over ponds are examples of measures that
can be taken to avoid poisoning of wildlife.
MITIGATION OF POTENTIAL SOCIOECONOMIC IMPACTS
Socioeconoraic impact mitigation measures can both enhance the
benefits of heap leach operations accruing to the local community and
minimize adverse impacts. Most of the measures suggested here can be
accomplished within a cooperative working environment between raining
companies, local officials and affected residents. Such an arrangement
is appropriate given the limited and frequently site-specific potential
adverse impacts associated with heap leach operations.
Prepare and obtain county approval of a comprehensive socio-
economic impact assessment prior to the granting of a condi-
tional use permit. This action would provide for systematic
considerations of site-specific socioeconomic mitigation
prior to project implementation.
Prepare periodic (bi-annual) reporting by the mine operator,
of selected key socioeconomic information, such as employ-
ment, payroll, workforce residency, taxes, and anticpated
activities and employment. These data will enable the county
245
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to compare actual Impacts to those projected by the preproj-
ect assessment and to take corrective measures If impacts are
either more or less severe than anticpated.
Mine operations can substantially increase both traffic and
road damage in the area. Therefore, mine operators could
enter Into cooperative agreements with affected jurisdictions
to assist in road maintenance and improvement efforts.
Agreements typically consist of financial assistance services
in kind.
Make initial and recurrent purchases of materials and sup-
plies within local communities, to the extent that such items
are available at costs comparable to those from suppliers
outside the area. This action would generate maximum sales
tax revenues in the local economy.
Adopt operating policies and procedures to minimize the
impacts from noise, dust, and changes in esthetics/visual
quality on adjacent landowners. Examples include: estab-
lishing buffer zones between active area of operations and
adjacent land uses; conducting blasting operations only
between 7:30 a.m. and 5:30 p.m. Monday through Friday;
regulating all vehicle speeds on public access and mine roads
in the vicinity of residences or other non-industrial
developed areas; and limiting offsite heavy truck and equip-
ment operations and deliveries to daylight hours.
Employ natural terrain, timber stands, or other features to
minimize visual or aesthetic changes from the major tour-
ist-oriented highways and developed ski areas. Consider
visual impacts and how they can be reduced in the placement
and design of the mine and related facilities.
Avoid direct interference with developed downhill ski areas
through the establishment of buffer zones between mining
activities and the ski facilities.
246
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If multiple heap leach operations occur in an area, addi-
tional infrastructure capacity improvements may be necessary.
Cooperative assistance by mine operators could include direct
monetary grants, loan guarantees, or services in kind.
Priorities could be established on an annual basis by a
committee representing the mining industry, local government,
and local residents.
247
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CHAPTER 6
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255
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APPENDIX A
EXAMPLE HEAP LEACH PROJECTS
STIBNITE PROJECT - PIONEER METALS NEAR YELLOWPINE, IDAHO
The description of Stibnite is based on the literature (Josey et
al. 1984 and Stotts, 1985) and a site visit. The Stibnite project is
located in Valley County, central Idaho, approximately 150 kilometers
(95 miles) northeast of Boise. Yellowpine, 23 kilometers (14 miles)
from Stibnite, is the nearest community. Yellowpine and the project
site are reached via McCall or Cascade and some 100 kilometers (80
miles) of gravel, mountain road. The mine and process facilities are
at elevations ranging from 2,000 to 2,300 meters (6,500 to 7,500 feet)
on U.S. National Forest land. West End Creek and Meadow Creek are
tributaries of Sugar Creek, which is a tributary of the East Fork of
the South Fork of the Salmon River. The Stibnite treatment facilities
and offices are located in the Stibnite Valley, 5 kilometers (3 miles)
from the mine itself. The site topography is typical of central Idaho,
with narrow steep side canyons and rapidly flowing streams. Because of
the climate, mild summers and long, cold winters, the operation is
limited to about 100 working days per year.
Early history of the district dates back to 1914 when claims were
staked in the Hennessy and Meadow Creek areas. The Bradley Mining
Company of San Francisco acquired the claims in 1927 and began mining
gold/antimony ore. Operations continued until 1938. Another open pit
mine near Yellowpine began operations in 1937 on gold/antimony.
Tungsten was discovered at Stibnite in 1941 and, because of the World
War II effort, an active tungsten mining and processing facility was
put in operation. This continued until 1952 and was the largest
domestic producer of tungsten during World War II. After tungsten was
exhausted in 1945, large scale mining for antimony and gold was carried
out. The West End deposit now being mined by Stibnite was discovered
in the early 1940's by the Bradley Mining Company. It is a dissemi-
nated low grade deposit which was not economical to mine at the time.
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In 1972, a soil sampling program conducted by the U.S. Geological
Survey showed anomalous geochemlcal gold values In West End Canyon. A
Vancouver, B. C., Company, Twin River Ventures Ltd., optioned the
property In 1973 and drilled two diamond drill holes. The results of
these test holes were encouraging. In 1975, Canadian Superior Oil took
over the lease and acquired operating control. After further explora-
tion, development drill work, metallurgical test work, engineering and
environmental studies, a decision to develop the property was made.
Construction began in July 1981 on the haul road and clearing of
the mine area. One year and 9.8 million dollars later, operations
began. The first ore was delivered to the crusher In July 1982. In
early 1986, Pioneer Metals was formed to take over the property. The
property did not operate during 1985.
Geology
The district lies along a margin of the Idaho Batholith within the
Salmon River Mountains. It is underlain by a large roof pendant of
meta-sedimentary rocks. Both these rock types are host to gold-bearing
mineralization. The roof pendant is cut by three major, northeast
trending faults and the north-south striking Meadow Creek fault. The
Meadow Creek fault is traceable for almost 10 kilometers (6 miles) and
dips steeply to the east with an average width of 60 meters (200 feet).
The two major Yellowpine district producing mines, the Yellowpine
and the Meadow Creek Mines, are located within plutonic rocks along the
Meadow Creek Fault. The mineralization Is described as hydrothermal
replacements in fractured zones. Apparently the earliest mineraliza-
tion was gold-bearing pyrite and arsenopyrite followed by scheelite and
then stibnite. Areas high in tungsten and antimony do not generally
carry high gold grades. Visible gold is absent in the district.
Along the West End Fault, where the gold mineralization occurs,
brecciation caused by movements along the major fault planes provided
the conduit system for the hydrothermal fluids to deposit coarse
calcite, iron, arsenic sulfides, and gold as fracture fillings.
Sulfide mineralization lies below an oxide zone and consists primarily
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of pyrite and arsenopyrite. However, this mineralization has not been
explored. The ore which is cyanide leachable is in the oxidized zone.
That zone is approximately 60 meters (200 feet) deep in the West End
Fault Area. While there appears to be some association between hydrous
iron oxides in the iron stained and fractured rocks, and residual gold,
it has not been possible to directly correlate rock color and ore
grade.
Exploration by Superior Mining involved 92 diamond and reverse
circulation rotary drill holes. Stibnite ore reserves, are estimated
to be 2,336,000 metric tons (2,575,000 short tons) of ore with an
average cyanide recoverable ore grade of 2.2 grams per metric ton
(0.064 troy ounces per short ton) of gold. The waste to ore ratio was
indicated as 2 to 1. At the end of the 1984 season after recalculating
reserves based on findings from the first two seasons of operation,
reserves remaining totalled 2 million metric tons (2 million short
tons) at an average, cyanide-recoverable gold grade of 2.14 grams per
metric ton (0.0623 troy ounces per short ton).
Mining
Conventional open pit methods are used to mine the ore. The ore
zone is on a northeast facing slope at the end of a ridge. Economic
grades of gold occur in three separate ore zones. Two smaller areas at
the top of the ridge were mined out in the first years of operation.
The main ore zone is on the slope at a lower elevation. The ultimate
pit dimensions for this main area will be about 260 meters (850 feet)
wide by 370 meters (1,200 feet) long and 200 meters (660 feet) deep
along the high wall side. The three mine locations total an area of
about 18 hectares (44 acres).
The operating season is approximately 100 working days, from June
and through October. The production rate is about 15,000 metric tons
(17,000 short tons) of waste and ore per day. With a waste to ore
ratio of 2 to 1, approximately 5,000 metric tons (6,000 short tons) per
day of ore will be mined over the life of the mine.
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Mining is performed by a contract mining company under a cost
reimbursable contract. The mining contractor is supervised by the
company staff, wh,ich includes a survey crew that directs the contrac-
tor's operations. Two 10-hour shifts, 5 days per week are worked.
Drilling is done on a 3- by 3-meter (10- by 10-foot) pattern to depths
of about 7.3 meters (24 feet) with 2 drill rigs. All drill holes are
sampled as part of the ore grade control program. Ore is blasted on
day shift only using ANFO at a powder factor of 0.12 kilograms per
metric ton (0.25 pounds per short ton). In some areas, ripping with a
dozer can be used to break the rock. Benches tend to be narrow so
entry to the benches may be constricted. A hydraulic front shovel with
a 5.0 cubic meters (6.5 cubic-yard) bucket is used to load ore. The
waste and ore are hauled distances ranging from 2 to 8 kilometers (1 to
5 miles) using 30- and 35-metric ton (35- and 40-short ton) off-road
trucks. Road grades along the haulage route, range from a 10 percent
decline to an 8 percent incline.
Control of ore grade is based on blast hole sample assays. After
careful logging of the drill holes by geologic technicians, samples are
tagged and hole sites staked for surveyors. Excavation advance is
mapped on a shift-by-shift basis, based on assay results, allowing for
mining control and ore and waste tonnage calculations. The tonnages
are then checked against truck count tonnages. Further grade control
is achieved by automatic sampling during the crushing step where the
crush ore stream is sampled some 25 times per hour.
Crushing
At the crusher location, the ore is dumped from the haulage truck
onto a storage pile. The ore breaks down in the mine to a relatively
small size, but the moisture content of the ore normally results in few
problems with blowing dust.
Ore from the stockpile is reclaimed by front end loader for
introduction to the crushing system (Figure A-l). Through a series of
grizzly, screens and crushers connected by conveyor belt, the ore is
reduced to less than 3.18 centimeters (1.25 inches) in diameter. The
259
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FIGURE A-1
PIONEER METALS STIBNITE PROJECT
BLOCK FLOW DIAGRAM
ORE HEAPS
DORE
PRODUCT
260
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crushers include a 110- by 91-centimeter (42- by 36-inch) primary jaw
crusher, a secondary 2-meter (5-foot) cone crusher, and a companion 76-
by 100-centimeter (30- by 41-inch) secondary roll crusher. The reduced
ore is fed to an open storage pile by conveyor where lime for pH is
being added to the ore at a rate of about 0.68 kilograms (1.5 pounds)
of lime per standard ton of ore. The crusher installation is portable
and trailer-mounted. It operates 10 hours per day, 5 days a week with
power supplied by a 400-kilowatt diesel generator.
Leaching
From the storage pile, the ore is loaded by front end loaders into
30-metric ton (30-short ton) trucks, which transport the material to
the prepared leaching area. The leaching area consists of five pads
which measure approximately 75- by 100-meters (250- by 350-feet)
(Figure A-l). The pads are sloped 1 percent inward and toward a drain
corner. They are above the surrounding grade and are well bermed along
the edges.
The plant in the process area is graded so that any solution
spillage and/or runoff in the plant will run toward the storage ponds.
Geotechnical investigations on the site prior to construction
indicated a possible deflection in excess of 1 percent for the loaded
pads. Therefore, care was taken in pad design to provide a somewhat
flexible pad base.
The pads were prepared by clearing, cleaning and scraping the soil
surface and then placing 3 centimeters (1 inch) of less than 100 mesh
tailings from one of the earlier Bradley mining operations on top. A
30-rail PVC liner was placed on top of the tailings (Figure A-2). A
coarse geotextile fabric was placed over the PVG liner. A 0.3-meter
(1-foot) layer of washed and open graded coarse rock was placed on the
geotextile fabric. An 8-centiraeter (3-inch) layer of asphalt with an
asphalt seal covered the rock. The asphalt pad surface is protected
during pad loading from heavy traffic by a 30- to 46-centimeter (12- to
18-inch) thick layer of crushed ore.
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FIGURE A-2
TYPICAL PAD AND POND LINER AT STIBNITE MINE
PAD SECTION
ASPHALT SEAL
8 cm ASPHALT
30 cm WASHED BASE GRAVEL
PROTECTIVE FABRIC COVERING 30 MIL PVC LINER
5cm OLD TAILINGS
ORIGINAL GROUND
POND LINER SECTION
— 50 MIL HYPALON LINER
— GEOTEXTILE FABRIC
— ORIGINAL GROUND
tMODIFIED FROM STOTTS, 1985)
262
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Ground water flow from under the pads is collected by a continuous
perforated drain pipe on the downhill side of the pads. It is 1 meter
(4 feet) below the PVC liner surface and runs the length of the five
pads. The outlet of this perforated pipe is sampled daily and analyzed
for free cyanide to detect any leaks into the ground water from the pad
area. The pipe discharges outside the plant area.
Also on the downhill side of the pads, a continuous perforated
drain pipe lies on top of the PVC liner. Its purpose is to collect any
solution which would seep through the asphalt layer. Discharge from
this pipe is monitored and flows into the pregnant storage pond.
During the operating season the outlets of this drain pipe and the
ground water drain pipe are sampled and analyzed daily for free cya-
nide.
The heap is constructed by 8-cubic meter (10-cubic yard) haul
trucks dumping ore at the foot of the heap face. A loader with a
3-cubic meter (A-cubic yard) rollover bucket then pushes the ore up the
face of the heap. This method is thought to reduce segregation of
coarse and fine ore. Each pad holds between 27,000 and 33,000 metric
tons (30,000 and 36,000 short tons) of ore, with an average pad height
of about 4.3 meters (14 feet).
The entire leach cycle takes about 50 days. Ten days are used for
loading the pad, 20 days for leaching and draining, 10 days for neu-
tralizing residual cyanide and 10 days for unloading. Each of the five
pad areas is at a different point in the cycle, allowing for a continu-
ous operation.
An alkaline cyanide solution is sprayed on the level, upper
surface of the heaps. The solution spray rate is about 3 x 10 cubic
meters per second per square meter (0.005 gallons per minute per square
foot) of heap area for a total flow to heap of some 0.01 to 0.02 cubic
meters per second (200 to 300 gallons per minute) of solution.
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Destruction or neutralization of cyanide is required by permit
prior to disposal of leached ore. Therefore the cycle is operated to
minimize cyanide levels at the end of the leach phase. The cyanide
content of the solution at the beginning of leaching is 1,000 to 1,100
mg/1. At the end of the cycle, it will have declined to less than 250
mg/1. Cyanide consumption is about 0.10 kilograms per metric ton (0.20
pounds per short ton) of ore. The 0.75 kilograms per metric ton (1.5
pounds per short ton) of lime added during crushing are sufficient to
maintain the pH level between 10 and 11 during the leaching phase.
Leach solution that has percolated through the heap collects in the
lower corner of the pad and is piped by gravity through the berm sur-
rounding the pad to an 3,050 cubic meter (805,000 gallon), hypalon-
lined, pregnant solution storage pond.
Processing
From the pregnant solution pond, the solution is pumped to paral-
lel carbon column lines. Each line consists of five tanks, 1 meter (4
feet) in diameter by 2 meters (7 feet) high, each holding about 680
kilograms (1,500 pounds) of activated coconut-shell carbon. The loaded
solution enters the bottom of each tank and cascades out of the top of
the upper tank to the bottom of the next tank. The flow rate is 0.01
to 0.03 cubic meters per second (200 to 400 gallons per minute) per
line for a plant capacity of 0.05 cubic meters per second (800 gallons
per minute). After passing through the carbon column system where the
gold is removed, the solution is discharged into a 1,010 cubic meter
(268,000 gallon) barren solution pond. This solution normally contains
less than 0.1 gram per metric ton (0.003 troy ounce per short ton) of
gold. After the addition of makeup water, cyanide and lime to the
baren pond, the solution is returned to the spray system for recycle to
the heaps. In addition to the pregnant and barren ponds, there are two
other ponds. These are for fresh water and for the neutralizing
solution for the alkaline chlorination process. The fresh water and
barren solution ponds are about 1,010 cubic meters (268,000 gallons)
while the pregnant and chlorine solution ponds are about 3,000 cubic
meters (800,000 gallons).
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Pond Design
The ponds were constructed by compacting rock-free soil along the
pond bottom and walls and placing a coarse geotextile fabric over the
compacted material for stability and liner protection. Over this is a
50-mil, reinforced hypalon pond liner (Figure A-2). The ponds are
checked for leakage at the start of each operating season by inspection
of seams and by checking pond level and comparing that to loss by
evaporation. Nearby monitoring wells are routinely sampled.
Cyanide Makeup
Makeup cyanide is added to the barren solution using a 1000-
kilogram (3000-pound) cyanide flow bin. Cyanide is discharged into a
mixing box. The mixing box is closed and cyanide is dissolved by
passing leach solution through the bottom of the mixing box. Operators
are protected by rubber suits, cyanide approved dust masks, face
shields and rubber gloves.
Carbon Stripping
The gold-containing solution passing through the carbon column
flows counter-currently to the carbon itself. This countercurrent flow
is achieved by advancing the carbon about once a day by eductors from
one tank to the other. Reactivated carbon enters the process when it
is added to the fifth tank. Fully loaded carbon from the first tank is
educted from that tank and fed to a storage bin. Carbon from each of
the four succeeding tanks is eductor advanced to the tank above it.
Carbon from the first tank is usually loaded to about 8,600 grams of
gold and silver per metric ton of carbon (250 troy ounces per short
ton). It is placed in a steel stripping vessel, 1.1 meters (3.5 feet)
in diameter by 3.4 meters (11 feet) high, which is capable of holding
1,000 kilograms (3,000 pounds) of carbon. Strong caustic cyanide
solution, cyanide at 10 grams per liter and caustic at 20 grams per
liter, is pumped at 120° C (250° F) and 9.5 x 10~ cubic meters per
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second (15 gallons per minute) from a stainless steel holding tank
through the stripping vessel. In this step, gold is stripped from the
carbon and is stored to await the next step of the recovery process.
The stripping operation takes about 5 hours.
The strip solution containing the gold is pumped through an
electrowinning cell in which the gold is plated onto the cathode and
thereby removed from solution. The electrowinning cell uses steel wool
as a cathode. Electrowinning involves a current density of 500 amps
and 2.5 volts. The steel wool is contained in baskets which are 0.6 by
0.6 meters (2 by 2 feet) by 10 centimeters (4 inches) thick and hold
about 1.0 kilograms (2.2 pounds) of steel wool. When the cathode is
loaded with 9,000 to 16,000 grams (300 to 500 troy ounces) of gold and
silver, the steel wool is removed and melted in a crucible furnace
along with borax and silica fluxing agents. The dore bars produced
average 65 percent gold and 35 percent silver. Off gases from the
furnace are scrubbed to remove objectionable metals. Only minor
amounts of mercury (below allowable levels) are reported and are
disposed of in the tailing area. The stripped carbon is removed from
the stripping vessel and is reactivated in a rotary kiln by heating it
about 66° C (150° F) for 30 minutes. Reactivation impurities, mainly
calcium, are removed by washing the carbon with nitric acid. The
carbon is then returned to the adsorption circuit for recycle.
Plant Area Surface Water
Because portions of Meadow Creek originally ran near the plant
area, the stream was redirected so that it is no closer than 90 meters
(300 feet) from the plant. Permits from both Idaho and the U. S. Army
Corps of Engineers were required to alter the stream course.
Cyanide Destruction
Cyanide destruction requires 2 days for draining the pile, 6 days
for neutralizing the pile with the hypochlorite solution and another
2 days for final draining of the neutralizing solution. Neutralization
continues until a 24-hour average free cyanide concentration in the
effluent from the pile of 0.2 mg/1 is reached. The alkaline chlorine
266
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solution is actually calcium hypochlorite, prepared as needed by adding
milk of lime to the spray pipeline followed by the injection of chlor-
ine gas into the slurry pipe venturi (Figure A-3). Chlorine consump-
tion is 2,000 kilograms (4,000 pounds) per day and lime requirement is
about 1 kilogram (2 pounds) of lime for each 0.5 kilogram (1 pound) of
chlorine. The resulting solution has a equivalent chlorine concen-
tration of 1,000 to 1,100 mg/1. This solution is sprayed on the spent
ore utilizing the same sprinkler system as is used for leaching. When
the 24-hour effluent average reaches 0.2 mg/1 free cyanide, based on
hourly samples, the heap is ready for disposal by removing the spent
ore from the pad by front end loaders and hauling it in belly dump haul
trucks to the Bradley mill tailing site. There, it is spread out in
thin layers, 0.3 to 0.6 meters (1 to 2 feet) deep, on top of the old
tailings and left undisturbed for 10 days to allow for degradation of
the remaining cyanide. The old tailings cover amounts to 3 or 3.7
meters (10 or 12 feet) after several lifts have been placed. Samples
of the material in the disposal area after 8 to 10 days indicate that,
on the average, there is a decrease of approximately 50 percent of the
free cyanide. Natural degradation, which has not been confirmed by
experimentation, is thought to involve a combination of mechanisms
including volatilization, oxidation, biodegradation, photodecomposi-
tion, and formation of stable complexes with available metal cations.
Monitoring
Fifteen surface water monitoring stations are sampled at least
three times during the June to October operating season. The samples
are analyzed for 20 parameters (Table A-l).
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FIGURE A-3
CHLORINATION CIRCUIT AT STIBNITE MINE
CHLORINE
POND
VENTURI
INJECTOR
VENTURI
INJECTOR
MIXING TANK
W/AQITATOR
PENNWALT
CHLORINATOR
LIME
BIN
Cla
STORAGE
HEAP
168
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Table A-l
SURFACE WATER MONITORING PARAMETERS
pH (lab)
Conductivity
Temperature (Field)
Total Kjeldahl nitrogen
Sulfate
An timony
Sodium
Lead
Zinc
Free cyanide (5 sites only)
Chlorine residual (field)
(4 Sites only)
Total colliform
Turbidity (lab)
Total suspended solids
Nitrate
Total phosphorous
Arsenic
Hardness (CaCOo)
Mercury
In addition, four sites are sampled every 7 days and analyzed for
turbidity, free cyanide and once a month, for arsenic and total sus-
pended solids. Ground water is monitored by sampling 10 shallow wells
three times each operating season on the same schedule as the surface
water samples. These analyses are conducted by an independent labora-
tory. The operator analyzes free cyanide, pH, residual chlorine in
some of the wells twice weekly- Other wells and the pad subdrain are
sampled daily. During the off-season, these walls are sampled and
analyzed monthly. The camp domestic water well and the plant utility
well are sampled three times each operating season and analyzed for
eleven parameters (Table A-2). They are also monitored for U.S. EPA
drinking water parameters in the spring and early fall of each operat-
ing season.
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Table A-2
CAMP DOMESTIC WELL AND PLANT UTILITY WELL
MONITORING PARAMETERS
Cyanide Calcium
Aluminum Magnesium
Arsenic Sodium
Antimony Iron
Hardness Mercury
pH
Consumables
Supplies and consumables for the facility must be transported over
130 kilometers (80 miles) of winding mountain roads which run alongside
major tributaries of the Salmon River. To minimize the chance of
accident and loss of dangerous materials to the surrounding environ-
ment, enclosed vans preceded by a pilot car are used to deliver chemi-
cals to the site. To diminish confusion and improve coordination with
suppliers and agencies involved in the area, Pioneer has elected to
work with only one vendor for the chemical supplies needed at Stibnite.
Facility Access
Access to the leaching and process area is restricted by means of
an 2.4-raeter (8-foot) high fence. The area is marked, advising un-
authorized personnel to stay out. The fence is maintained such that
wildlife access to the site is unlikely.
Winter Shutdown
The Stibnite region receives more than 790 millimeters (31 inches)
of annual precipitation. The majority of the precipitation is snow and
occurs between the months of December and April. The spring runoff
must be handled as part of the shutdown procedure in the fall. All
four ponds at the plant are drained. During the winter months, the
pond levels are monitored and as the water levels rise, the ponds are
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pumped. The discharge criteria for excess water require that during
the 24-hour sampling period the free cyanide concentration to be less
than 0.2 mg/1. Sampling takes place during discharge and if a sample
exceeds 0.2 mg/1 of free cyanide, the free cyanide is removed by the
hypochlorite treatment. The discharge solution is pumped from the
ponds at a rate of 0.01 cubic meters per second (200 gallons per
minute) through 10-centimeter (4-inch) PVC pipe for a distance of 2,000
meters (5,000 feet) to the old tailings area. It is discharged on the
tailings as a land application by spraying in a sprinkler system, which
further oxidizes any residual cyanide.
WHARF RESOURCES - BLACK HILLS, SOUTH DAKOTA
Wharf Resources operates a heap leaching facility in the Bald
Mountain District of the Black Hills, southwest of Lead, South Dakota.
The information presented below on Wharf Resources is based on a site
visit and personal communication with Mr. Luther Russell of Wharf
Resources. The Bald Mountain District is one of several mining dis-
tricts in an area in which perhaps hundreds of mines of various sizes,
mostly small, tried to achieve success. While perhaps best known for
its gold and silver production, the Black Hills were also mined for
other metals such as tin and tungsten. However, the most successful
mining has been for gold and silver. Regional geology and general
information on ore bodies that may be leachable in the Black Hills is
discussed in Chapter 3.
Prior mining activity on the claims, now under the control of
Wharf Resources, was by the Portland Mining Company which operated
until 1959. The pits worked by Wharf Resources include the Annie Creek
pit, which is now essentially mined out but does have perhaps 27,000
metric tons (30,000 short tons) of leachable ore remaining. The
present mining activity is in the Foley pit which is located near the
Terry Peak Ski Area. In the immediate vicinity there are a few newer
ski-resort condominiums.
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The Portland Mining Company operated the property as an under-
ground mine, while Wharf is presently mining by open pit methods.
Consequently, underground workings are frequently encountered. In
fact, in the Annie Creek pit, many of the old drifts open into the pit
walls. Wharf began operations in 1982 and currently ore reserves are
estimated at 4.5 million metric tons (5 million short tons) at a
stripping ratio of 2 to 1 waste to ore, with an ore grade of about 1.7
grams per metric ton (0.05 troy ounces per short ton) gold.
Mining
As stated, mining is by conventional open pit with advanced
drilling to a 0.6 meter (2-foot) depth on 3.7-meter (12-foot) centers.
The blast holes are sampled and assayed for gold and silver content to
determine if the block is ore or waste. The drill holes are loaded
with ANFO and broken by blasting to nominal 46-centimeter (18-inch)
rock. The powder factor is approximately 0.3 kilogram per metric ton
(0.5 pound per short ton) of broken rock. The broken ore is loaded by
front end loaders into 45-metric ton (50-short ton) trucks. There are
five such trucks to haul waste and ore. The haul distance to the waste
area is approximately 900 to 1,200 meters (3,000 to 4,000 feet). The
haul of ore to the leach pad is approximately 2,000 meters (7,000
feet). Three 8-hour shifts per day, 5 days a week are used for the
mining operations with 4,000 metric tons (4,000 short tons) of ore and
7,000 metric tons (8,000 short tons) of waste produced. The waste area
presently in use is known as the Ross Spring area. A new waste dis-
posal area is being cleared in the area of Squaw Creek. The waste
contains no sulfide material and, in general, the rock has been found
to be basic so there is no acid generation in the heap or waste piles.
Mining is conducted 10 months of the year. Advanced mine stripping is
done in the remaining two cold months. For purposes of noise level
control, blasting is carried out only between 9:00 am and 4:00 pm.
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Crushing
Two-stage crushing of the ore to less than 3.8 centimeters (1.5
inches) is accomplished with portable crushing plants. Ore is fed via
a 1.5- by 5.5-meter (5- by 18-foot) apron feeder and a feeder to a
primary jaw crusher and reduced in size to less than 15 centimeters (6
inches) (Figure A-4). Undersize ore from the wobbler feeder is moved
by conveyor to the crushed ore pile. The crushed ore is moved by
conveyor to a 450-metric ton (500-short ton) coarse ore surge pile
equipped with a plate feeder delivery to a second conveyor that moves
ore up to a 2- by 5-meter (5- by 16-foot) double deck vibrating screen
with 6.4 centimeter (2.5 inch) square openings on the upper deck and
3.8- by 6.4-centimeter (1.5- by 2.5-inch) on the lower deck. Undersize
ore from the screen, less than 3.8 centimeters (1.5 inches), is con-
veyed to a fine ore pile. Screen oversize is directed to a cone
crusher and moved by a conveyor to the conveyor feeding the vibrating
screen ahead of secondary crushing. The ore breaks uniformly with
minimal generation of fine material. As the ore is conveyed to the
fine ore storage pile, lime is added at a rate of about 1 kilogram per
metric ton (2 pounds per short ton). This is necessary to ensure a
high pH during the cyanide solution leaching step.
Pad and Heap Design and Description
Ore is transferred from the fine ore surge pile by a front end
loader and a 45-metric ton (50-short ton) offroad truck to the heap.
The heaps are approximately 6.1 hectares (15 acres) in area and hold
about 1.4 million metric tons (1.5 million short tons) of ore. Seven
lifts, each 4.6 to 5.4 meters (15 to 18 feet) in height, for a total
height of about 30 meters (100 feet) comprise the heap.
The soil base for the pad is cleared and graded to the desired
profile. It is compacted and 20 centimeters (8 inches) of clay are
placed on the compacted base (Figure A-5). The clay is compacted and
the surface cleared of any rocks. A 30-mil PVC liner is placed on top
273
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FIGURE A-4
WHARF RESOURCES
BLOCK FLOW DIAGRAM
u/sOJScm
*
3.18cm
ON-GOING
LEACH
SOLUTION
NaCN
MAKEUP
•?"
HEAP LEACH
(one time use.
permanent heap )
S 2m LIFTS
-------
FIGURE A-5
TYPICAL PAD AND POND LINERS AT ANNIE CREEK MINE
PAD SECTION
20-30 cm OF 1.9cm CRUSHED ORE
GEOTEXTILE FABRIC
30 MIL PVC LINER
20 cm CLAY
COMPACTED SOIL BASE (FRENCH DRAIN FOR SECOND HEAP)
CONTINGENCY POND LINER SECTION
20 cm COMPACTED
COMPACTED SOIL BASE
PROCESS POND AND OVERFLOW LINER SECTION
- 38 MK. HYPALON
- 20cm COMPACTED
COMPACTED SOIL BASE
NEUTRALIZATION POND LINER SECTION
38 MIL HYPALON
30cm SAND (CONTAINS LEACHATE COLLECTION SYSTEM)
30 MIL PVC
30 cm COMPACTED CLAY
COMPACTED SOIL BASE
275
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of the clay and the seams are carefully sealed. A geotextile fabric is
laid on top of the PVC liner to serve as protection for the liner and
20 to 30 centimeters (8 to 12 inches) of 1.9-centimeter (0.75-inch)
crushed ore are placed on the geotextile fabric to provide for drain-
age.
In the first production heap, an 20-centimter (8-inch) perforated
pipe was run down to the pad base surface to provide an intermediate
drain. The second heap presently under construction has additional
drain lines and will drain from the center line to the edges of the
pad. The pad is surrounded by a 3-meter (10-foot) buffer zone and the
pad edges are bermed to 0.6 meter (2 feet) to prevent escape of any
runoff from the heaps. The buffer zone will also minimize solution
spray drifting from the pad area.
Initially, solution runoff from the heap was directed to the
storage ponds by lined, open ditches. The solution now moves to the
pond by pipe.
Forty-five-metric ton (50-short ton) trucks move ore from the fine
ore pile to the heap. There it is carefully dumped to minimize segre-
gation. It is spread by a dozer until a lift is nearly completed.
When room on each lift becomes available to establish the leaching
lines, the area will be leached. In the meantime, building of the heap
continues while leaching begins. When the first lift is completed, the
second lift is started, with access provided by a roadway along the
edge of the first lift. The next lift is smaller than the proceeding
lift by the width of the roadway. In the first 1.4-million-metric ton
(1.5-million-short ton) heap, which is now completed and in full leach,
seven such lifts were used and the heap resembles a stepped pile with
each subsequent lift smaller in area. A first lift for the second heap
is well advanced and preparations of the pad base and liner are also
well underway.
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Leaching
As stated earlier, leach lines are draped over the pile on about
10-meter (40-feet) spacing. Sinninger wobbler sprinklers are 10 meters
(40 feet) apart on each of these lines. The leach solution is a
cyanide solution with a pH range of 10 to 11, typically 10.2, and the
sodium cyanide content of the ongoing solution is about 500 mg/1. The
pumping rate to the completed heap now in operation is 0.038 to 0.044
cubic meters per second (600 to 700 gallons per minute). The leach
solution which has percolated through the heap is directed to the
pregnant liquor storage pond. The pregnant solution contains 1 mg/1 of
gold, 0.003 ppm mg/1 silver, 2 to 3 mg/1 of iron, 2 to 3 mg/1 of
arsenic, and traces of cobalt, lead, nickel, and mercury.
The leach procedure involves moving the leach lines when the gold
content of the solution coming off the heap begins to decrease (typic-
ally about every 20 days). The lines are moved an appropriate distance
at that time and the leaching action continues. According to the
process plant manager, if the heap pile is inactive after leaching,
placing the leach lines back in the same area again results in in-
creased gold pickup for a short period of time.
The anticipated life of a heap, including heap building followed
by leaching, is approximately 3 years. Continuous operation is desir-
ed, i.e, upon completion of the heap building, completion of leaching
the entire heap closely follows.
Solution from the heap is piped by gravity to the pregnant liquor
storage pond. The pregnant pond and three other ponds are adjacent to
the process plant.
Pond Design
The four ponds include a 13,000-cubic-meter (3.5-million-gallon)
pregnant solution pond, a barren pond of about 19,000-cubic-meter
(5-million-gallon) capacity, an overflow pond of about 19,000-cubic
meter (5-million-gallon) capacity and a contingency pond of about
34,000-cubic-meters (9 million gallons). The pregnant pond is the
highest topographically, followed by the barren pond, the overflow pond
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and the contingency pond. They are arranged so that the upper pond can
overflow into the lower ponds before overflowing the entire pond
system.
The ponds are constructed by removing the appropriate amount of
soil, sloping and compacting the sides and base, then placing 20
centimeters (8 inches) of clay on the prepared soil. The clay is
compacted and a 30-rail hypalon liner is placed on top of the clay
(Figure A-5). For the contingency pond, only the clay liner is in
place. The very low permeability of the clay liner (approximately 10
centimeters per second) provides ample protection from leakage from the
pond through the liner if an event required use of the contingency
pond. Lysimeters are placed in the clay under the hypalon liner and
are monitored to detect any leakage through the liner. The ponds are
checked annually for any leakage through the hypalon and appropriate
repairs made if any leaks are found.
A fifth pond is being constructed some distance away from the
other ponds. It will be designed to hold about 23,000 cubic meters (6
million gallons). Wharf Resources is required by the state to double-
line the pond with a soil base, 30 centimeters (12 inches) of clay, a
30-mil PVC layer, 30 centimeters (12 inches) of sand, a geotextile
fabric layer and finally a 30-mil hypalon liner. The purpose of the
pond is to hold a cyanide neutralizing solution which, following
completion of the leaching step, will be circulated onto the heap to
destroy the cyanide. At the present time, a hydrogen peroxide solution
is being considered for that application.
The leaching operation takes place approximately 10 months of the
year. The other 2 months present problems because the leach lines
cannot be moved due to snow and pipe freeze-up. However, Wharf Resour-
ces has noted that the temperature within the heap during the winter
can be as high as 2.8° C (37° F) as a result of chemical reactions
underway in the leaching process. It is anticipated that Wharf
Resources will try to operate during the winter of 1986.
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Recovery Plant
Solution from the pregnant pond Is pumped into the recovery plant,
which uses carbon adsorption to remove gold from solution. The carbon
column section is standard design and configuration. The solution
enters the uppermost carbon columns, which is a tank approximately 3.7
meters by 1.8 meters (12 feet by 6 feet). The solution is pumped
through the tank at the rate of 45 liters per second (720 gallons per
minute). Each of the tanks contains approximately 1 metric ton (1
short ton) of activated coconut carbon and the solution upflows through
carbon, cascades down to the next tank until it completes a circuit of
five tanks. The flow is countercurrent. While the solution flows down
through the five columns of carbon, the carbon from the lower tank is
advanced to the next tank upstream. The carbon from the first column
is essentially depleted of gold.
Carbon Stripping
The loaded carbon from the first adsorption column is transferred
to five pressure stripping vessels where the solution contacts the
stripping solution containing 15 kilograms caustic per metric ton (30
pounds caustic per short ton) of solution and 1.5 kilograms of sodium
cyanide per metric ton (3 pounds of sodium cyanide per short ton) of
solution. The stripping temperature is about 130° C (270° F). Strip-
ping retention time is about 12 hours. The carbon is reactivated by
heating in a gas-fired rotary kiln at a rate of 110 kilograms (250
pounds) per hour to a temperature of 590° C (1,100° F).
Wharf Resources has found that it is not necessary to acid wash
the reactivated carbon, as is the practice of most operations. In-
stead, simple soft water wash is adequate to return the carbon to its
normal activity. The stripped solution containing the gold at a
concentration of 86 grams per metric ton (2.5 troy ounces per short
ton) of solution is electrowon by standard procedures on stainless
steel wool. When the wool cathode reaches a gold content of 7,000 to
10,000 grams per kilogram (100 to 150 troy ounces per pound), the
cathode is harvested and then converted to dore in a propane-fired
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furnace with the addition of appropriate fluxes. The dore assays
approximately 90 percent gold and 10 percent silver. The dore is
shipped to a custom refinery for separation and refining to marketable
gold.
Water Use
After the initial process water is obtained, an average of 0.004
cubic meters per second (70 gallons per minute) is used to augment the
water supply for the leaching operation due to 5 to 10 percent evapora-
tion losses.
Spill Containment
The entire leach and process plant area is graded so that any
spills will run to the pond system. Monitoring wells are positioned
around the property and lysimeters are used to detect possible leaks
through the pond liner.
Monitoring
The monitoring program for potential leaks at the facility uses
lysimeters underneath the pads and ponds. The pad currently under
construction will have a gravity drain system under the liner which
will open to the pregnant solution ponds. A neutralization pond
currently under construction will use a similar detection system but
will be equipped with a standpipe for sampling. Each of the units is
(or will be) sampled monthly if there is any flow.
There are eight surface water sampling stations associated with
the property. They are positioned so as to be able to sample both
upgradient and downgradient from the facility. Their locations were
selected on the basis of major drainage pathways to and through the
site.
For monitoring ground water there are 6 wells in excess of 30
meters (100 feet) in depth. Their locations are associated with the
ground water pathways in the area.
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Surface water stations and the ground water wells are sampled
quarterly and the samples are analyzed by a State of South Dakota
certified laboratory. Some 20 parameters are involved in these
analyses including metals (Al, As, Cd, Cu, Fe, Pb, Mn, Hg, Se, Ag, Zn),
BOD, TSS, IDS, carbonate, alkalinity, cyanide, and pH.
The analytical results are submitted to the state for review. To
date, Wharf Resources detected one small leak in their system. A liner
in the barren pond had a small tear and some cyanide solution seeped
into the clay liner below. There was- also a reported overflow about
the same time during spring runoff, from the barren pond to the over-
flow pond, which had only a clay liner at that time. It is understood
that there was no release of solution from the overflow pond; the clay
liner in that pond effectively prevented any loss of solution to the
ground water.
Site Power Supply
Power is provided by the Black Hills Power and Light Company and a
backup diesel generator is onsite for handling pumps in the event of
emergencies.
Surface Water Runon Control
Surface water is diverted around the plant area by diversion
ditches. The ditches are sized for a 480- millimeter (19-inch), 6-hour
probable maximum precipitation event as required by the State.
Site Access
The entire area is enclosed by a 2.4-meter (8-foot) fence to limit
wildlife and human access. The gate leading into the property has an
around-the-clock guard.
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REFERENCES
Josey, W. L., W. A. Cohen, W. G. Stotts, R. J. Leone, and B. R. Flesh-
man. 1984. Gold Heap Leach Project at Stibnite, Idaho. SME-AIME
Fall Meeting. Denver, Colorado. October 24-26, 1984.
Stotts, W. G. 1985. Handling cyanide at Superior Mining Company's
Stibnite Heap Leaching Operation. In D. Van Zyl (ed.). Cyanide
and the Environment. Proc. of a Conference. Tuscon, Ariz. Dec.
11-14, 1984. Department of Civil Engineering, Colorado State
University. Ft. Collins, Colorado.
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APPENDIX B
CYANIDE CHEMISTRY
OVERVIEW
Cyanide may occur in many forms. The forms of cyanide relevant to
a discussion of heap leach mining are:
Free cyanide - Cyanide ion (CN ) and molecular hydrogen cyanide
(HCN). The distribution between cyanide and HCN is dependent on
pH with HCN predominant below pH 9.36 (20° C).
Simple cyanide - an alkali or metal cation and cyanide. An
example of a soluble simple cyanide is sodium cyanide (NaCN),
which is used in process solutions at heap leach operations.
Complex cyanide - metal cyanide complexes and their salts. Metal
cyanide complexes are divided based on their stability into weak
complexes containing zinc or cadmium, moderately strong complexes
containing copper, nickel, or silver, and strong complexes con-
taining iron, cobalt, or gold. The salts are relatively insolu-
ble.
Cyanogenic glycosides - organic compounds introduced naturally
into the soil which release cyanide upon hydrolysis. Plants are
one of the most common sources.
Methods for measuring cyanide in water and the species of cyanide
detected by each method are:
Free cyanide - measures the amount of HCN and CN .
Weak acid dissociable cyanide - measures free cyanide, and com-
plexes of Cd, Cu, Ni, Ag, and Zn.
Total cyanide - measures free cyanide, weakly acid dissociable
cyanide and most inorganic complex cyanides including Fe but
excluding Au, Co, and some of the Pt metals.
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Cyanide amenable to chlorination - measures the difference between
total cyanide concentration before and after chlorination.
Researchers have been experimenting with different types of leaching
and analytical procedures for cyanide measurement in solid samples such
as spent ore.
Cyanide is a very reactive and relatively short-lived contaminant.
Processes which tend to degrade or transform free cyanide in the
environment are volatilization of HCN, reaction of cyanide to form
ammonia and formate, oxidation, complexation with metallic ions,
biological activity, conversion to thiocyanate (SCN ) and sorption.
Cyanide may be released from simple and complex cyanides depending on
the stability of the specific compound or complex. In addition, iron
or cobalt cyanide complexes, which are strong complexes, may undergo
photochemical degradation by sunlight and release free cyanide.
Cyanide released from simple and complex cyanides will be subject to
degradation or transformation processes.
Volatilization is probably the most significant process in the
natural degradation of cyanide in surface waters. Generally, free
cyanide would be more mobile in surface waters with higher pH, lower
temperature, lower levels of metals and sulfide, organic and inorganic
suspended matter, and which have little interaction with sediment.
Surface water bodies with stagnant, deep conditions and little surface
area would promote high mobility of cyanide. Volatilization rates of
HCN from ground water may be less than those from surface water. Other
processes that tie up cyanide, such as sorption and complexation, may
be much more important in limiting the mobility of cyanide in ground
water than in surface water. Reaction of cyanide to ammonia and
formate may also be an important process to reduce concentrations of
cyanide in ground water.
Cyanide is more mobile in soils with anaerobic conditions. The
limit for effective microbial degradation of cyanide was found to be 2
mg/1 based on studies of a sewage waste sream (Coburn, 1949). Cyanides
and cyanide-yielding compounds such as fertilizers and pesticides
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applied to aerobic soils readily degrade (Fuller, 1985). Other factors
affecting the mobility of cyanide in soil are clay content, depth of
soil, content of iron oxides or other metal oxides, pH, and presence of
organic matter. Mobility of cyanides is greatest in soils with high pH
and low clay content.
The basic chemical process used in a heap leach mining operation
is the complexation of Au and Ag from the ore with a sodium cyanide
solution. One of two processes, carbon adsorption or zinc precipita-
tion, can be used to recover the precious metals from the pregnant
solution.
Neutralization, or a rinsing of the ore heaps, is used to reduce
the levels of cyanide remaining in heaps after the ore is spent.
Various western states require that the rinsing procedure continue
until the cyanide concentration is reduced to a specified level or a
certain pH is obtained. The final cyanide concentrations specified by
states using free cyanide analyses ranges from 0.2 to 5 mg/1, and from
0.01 mg/1 to 100 mg/1 in states using total cyanide analyses. Although
little data is available, sampling of heaps after the rinsing procedure
is completed generally shows less than 10 mg/kg of free cyanide remain-
ing in the heaps. Subsequent sampling shows a decrease of cyanide with
time.
A variety of methods are used to destroy cyanide in process
solution either during operation or upon closure, and rinsing solution
used to neutralize the spent ore heaps. Treatment processes that are,
or may be, used at leaching operations are natural degradation, alka-
line chlorination, hydrogen peroxide, Inco process, and biological
treatment.
Heap leach mining wastes contain free cyanide (HCN and CN ), metal
cyanide complexes, and salts of metal cyanide complexes. The amount of
free cyanide in these wastes is dependent upon the rate of volatiliza-
tion of HCN to the atmosphere. An important control on volatilization
is pH; below a pH of 9, HCN is predominant over cyanide ion.
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Metal cyanide complexes such as Iron, copper, zinc, nickel,
cobalt, and cadmium, which are the most common at gold and silver
operations (Huiatt, 1985), decompose and release cyanide ion at varying
rates. Zinc and cadmium complexes, the least stable complexes, readily
decompose during the rinsing process as free cyanide decreases. Strong
complexes such as iron cyanide complex may remain in the spent ore.
Iron cyanide complexes have been found to degrade in solutions exposed
to ultraviolet light, but the photochemical effect on the solid species
is unknown. Iron, nickel, cobalt, and copper salts of iron complex
cyanide ions are very sparingly soluble and release very small amounts
of free cyanide in the spent heap pile.
In addition to volatilization directly from the mining wastes,
there is a secondary transport process whereby cyanide and any soluble
metal cyanide complexes may be leached from the mining wastes and
transported into the environment if uncontained. The accidental
release of cyanide process solution is also possible. Several chemical
and biological processes have the potential to attenuate cyanide when
it is released to the environment.
CHEMICAL FORMS OF CYANIDE
A large number of organic and inorganic chemical compounds contain
cyanide. Cyanide occurs as a cyano group (CN) in the molecular struc-
ture of the compound. In solution, the cyanide ion (CN ) is a nega-
tively charged, diatomic species, which may complex with both inorganic
and organic compounds. Since most metals tend to form positive ions,
they may readily react with cyanide. The characteristics of cyanides,
particularly the high level of stability for some of the metal cyanide
complexes, can be explained by its bonding properties. For the pur-
poses of this report, four different forms of cyanide, free cyanides,
simple cyanides, complex cyanides, and cyanogenic glycosides (organic
compounds containing cyanide) will be discussed below.
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Free Cyanide
Free cyanide in solution is the total concentration of cyanide ion
(CN) and dissolved molecular hydrogen cyanide (HCN). Hydrogen cyanide
is a colorless gas or liquid with a boiling point of about 25.5 °C
(77.9° F). The gas is less dense than air and flammable.
HCN or hydrocyanic acid, a weak acid, has a dissociation constant
of A.365 x 10~ at 20 °C (68° F) for the hydrolysis reaction between
cyanide ion and water:
CN~ + H20 = HCN + OH~ (1)
The relative amounts of CN and HCN as predicted by this relationship
are strongly dependent on the pH of the solution (Figure B-l). The
concentration of CN and HCN are equal at pH 9.36, the pK (log of the
equilibrium constant) of HCN at 20 °C (68° F) (Broderius, 1974). At pH
values below 9.36 and at 20° C (68° F), most cyanide exists as molecu-
lar HCN; 69.6 percent at pH 9; 95.8 percent at pH 8; and greater than
99 percent at pH 7. In natural waters most of the free cyanide concen-
tration would be in the form of HCN. Since HCN has a high vapor
pressure it readily evaporates depending on the solution concentration,
temperature, and pH. Higher temperatures and solution concentrations,
and lower pH values promote generation of gaseous HCN.
Simple Cyanides
Simple cyanides consist of an alkali (sodium, potassium) or metal
cation and cyanide. They can be represented by the formula A(CN) ,
where A is an alkali or metal, and x, the valence of A, represents the
number of cyano groups present. Solubilities of the simple cyanides
are a function of pH and temperature. Soluble compounds (particularly
the alkali cyanides) ionize to release cyanide as shown:
A (CN) = A+X + xCN~ (2)
X
Cyanide ions released would undergo hydrolysis as shown in equation
(1). An example of a simple cyanide used in heap leaching mining
operations is sodium cyanide (NaCN) which would dissolve and readily
hydrolyze as shown:
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FIGURE B-1
THE EFFECT OF pH ON DISSOCIATION
OF HYDROGEN CYANIDE
z
o
X
HCN
HYDROGEN
CYANIDE
i
Z
a
10
11
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Na+ + CN~ = HCN + Na+ + OH~ (3)
Complex Cyanides
Alkali-metallic cyanides are represented as A M(CN) , where A is
y ^
the alkali such as sodium of potassium, y is number of alkalies, M is
the heavy metal (ferrous or ferric iron, gold, copper or others), and x
is the number of cyano groups. The valence of the alkali (A) taken y
times plus the valence of the metal (M) is the value of x. Soluble
alkali-metallic cyanides dissociate to release the metal cyanide
complex ion, (M(CN) ) ™, by the reaction:
X
A M(CN)x = yA+(x) + (M(CN)x)~yW (A)
where w is the oxidation state of A in the original alkali-metallic
cyanide compound. The metal cyanide complex ion released may undergo
further dissociation and release cyanide ion. Another type of compound
with a similar formula is the complex ferro or ferric cyanide salts,
O [ Oj
where A and M would be a heavy metal and either Fe (ferrous) or Fe
(ferric), respectively. Some examples of metal cyanide complex ions
which may be found in process solutions of heap leach mining operations
3- - 2-
are Fe(CN), , Cu(CN)0 , and Zn(CN),
6 ' 2 ' 4
Cyanogenic Glycosides
Organic compounds yielding cyanide are introduced naturally into
the environment, particularly the soil. One of the most common natural
sources is from plants. A large number of plants (800 species) natu-
rally synthesize cyanogenic glycosides (Knowles, 1976). The general
formula is:
CN
R2
where RI = an alkyl or aryl group
R~ = a hydrogen atom or methyl group
R_ = usually, D-glucose.
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One of the best known cyanogenic glycosides, called araygdalin, occurs
in seeds and leaves of many members of the Rosaceae (rose) family
(Kingsbury, 1964). Many common vegetables also contain cyanogenic
glycosides such as maize, millet, field bean, kidney bean, sweet
potato, and lettuce (Oke, 1969). Generally, the glycoside is harmless,
but becomes toxic only when in vivo conditions permit hydrolysis of the
compound to liberate hydrogen cyanide (refer to Appendix C for a
discussion of toxicity).
ANALYTICAL METHODS
Standard methods for measuring cyanide that are most relevant to
the mining industry are described below. These methods include total
cyanide, free cyanide, weak acid dissociable cyanide, and cyanide
amenable to chlorination. Several problems associated with the ana-
lytical methods are also presented.
Methods for Water Samples
Total Cyanide
The acid reflux/distillation method measures the free cyanide and
the cyanide contained in complex iron cyanides, weakly acid dissociable
cyanide, and most inorganic complex cyanides except gold, cobalt, and
some of the platinum metals. The ASTM method (1981) uses a catalytic
agent to facilitate the breakdown of the metal cyanide complexes. The
hydrogen cyanide liberated by the distillation is collected in an
alkaline absorbing solution and can be measured by titration, colori-
metry, or specific ion electrode. The lower limit of detection for the
three methods are 1.0, 0.03, and 0.03 mg/1, respectively.
Modifications to the ASTM method to eliminate interferences caused
by thiocyanate have been developed. In the acid distillation techni-
que, decomposition agents such as hydrochloric acid/hydroxylamine,
tartaric acid, or phosphoric acid (Knechtel and Conn, 1981; Huiatt et
al., 1983) are used.
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The EPA procedures were last revised in 1984 as Method 335.2
(STORET No. 00720). This method is either a titrimetric or a spectro-
photometric analytical procedure similar to ASTM. Single laboratory
precision is reported as 85 percent and 102 percent recovery at 0.28
and 0.62 mg/1 CN, respectively. These recoveries were apparently
reported for water samples.
Free Cyanide
The methods for determining free cyanide include solvent extrac-
tion or sparging the HCN from solution and collecting it for later
measurements (Broderius, 1975, Montgomery et al., 1969; Schneider and
Freund, 1962).
Weak Acid Dissociable Cyanides
The method accepted by ASTM as a standard procedure for determin-
ing weak acid dissociable cyanides is called Method C, a variation of
one proposed by Roberts and Jackson (1971). The reagents used in the
distilling flask are acetic acid-sodium acetate solution buffered at pH
4.5 and zinc acetate. Gonter (1975) reported that cyanide was totally
recovered from cadmium, copper, nickel, silver, and zinc complexes.
Test work reported by Conn (1981) suggests that some (two percent)
breakdown of ferrocyanide could occur. No interference occurs in this
method by the presence of thiocyanate.
Cyanide Amenable to Chlorination
Cyanide amenable to chlorination is the difference between total
cyanide measurements before and an alkaline chlorination treatment.
Chlorination treatment oxidizes cyanide, HCN, cyanide from weakly
dissociated and moderately strong metal complexes, and thiocyanate, but
does break down the iron cyanide complexes or other stable complexes.
Refer to the section entitled, Complexation with Metallic Ions for the
stabilities of metal cyanide complexes. The sample is separated into
two portions; one is analyzed for total cyanide and the other is
analyzed for total cyanide after a treatment with sodium hypochlorite
at an alkaline pH for one hour. EPA uses Method 335.1 (STORET No.
00722) to determine cyanide amenable to chlorination.
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Methods for Solid Samples
EPA Method 9010 (U.S. Environmental Protection Agency, 1982) may
be used to analyze for total and chlorine amenable cyanides in solid
wastes or leachate. A draft testing method has just been released by
EPA to determine whether a waste is hazardous due to cyanide reactivity
(U.S. Environmental Protection Agency, 1986). The memo stated that on
a interim basis wastes releasing more than 250 mg HCN/kg waste should
be regulated as hazardous waste. Other methods for cyanide analysis in
environmental samples are currently being tested. The literature shows
that particular methods are suited to specific types of samples depend-
ing on the sample composition. Hendrix et al. (1985) has developed a
method producing reproducible results suitable for tailings samples.
After drying and thorough mixing, 5 grams of sample were mixed with 20
millimeters of 1 N NaOH and about 200 milligrams of PbCO-, and filtered
into a distillation flask. The filtrate was analyzed for total cyanide
by the ASTM method. Free cyanide was analyzed directly without the
caustic filtration pretreatment. J.L. Hendrix (University of Nevada at
Reno, personal communication, 1986) is also developing analytical
methods to determine the amounts of specific metal cyanide complexes
present.
Several different leachate solutions, deionized water, 1 N KNO^ in
water, and 1.25 N NaOH in water, were tested on samples from heap leach
piles by Ray (1985). The procedure for analysis consisted of leaching
a 20 gram sample in 100 millimeters of leachate solution for 24 hours
in the dark. After leaching, the sample was filtered (Whatman GF/C or
equivalent) until the final volume was 100 millimeters. The leachate
was then analyzed by the distillation/destruction method with a colori-
metric finish. The results for direct analysis (0.5 gram sample in
distillation flask) and the three leachate methods are presented in
Table B-l. Only the NaOH solution solubilized cyanide at a level
similar to that found in the direct analysis. The data also show that
reproducibility of results is greatly increased with the larger sample
sizes.
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TABLE B-l
COMPARISON OF LEACHING METHODS
FOR TOTAL CYANIDE DETERMINATION IN SOLID SAMPLES
a/
Leaching Method
Run # Direct Analysis ' PI Water 1 N KN03 1.25 N NaOH
(mg/kg)(mg/kg) (mg/kgJ (mg/kg)
1 45.2 0.8 0.6 142
2 125 0.6 0.4 47.9
3 77.5 <0.2 <0.2 43.2
4 57.3 <0.2 <0.2 109
5 179 0.6 <0.2 106
6 114 0.2 0.4 91.9
7 129 116
8 88.1 114
9 98.3
10 170
11 196
12 104
13 114
14 59.9
15 65.1
Mean 108 0.4 0.2 96.2b/
+ 1 S.D. 45.9 0.3 0.3 34.3
Analysis of 0.5 g sample.
If values from runs #2 and #3 are omitted, the mean is 113 +_ 16.5
(_+ 1 S.D.).
Source: Modified from Ray, 1985.
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Several other examples which illustrate the diverstiy of methods
used for solid samples are described below:
Engelhardt (1985) and Milligan (1985a) - 200-gram split of spent
heap material (reprocessed tailings) was agitated for one hour
with 200 milliliters of distilled water; after filtering, the pH
was adjusted to 12.0 with sodium hydroxide, and then analyzed for
free and total cyanide.
Stotts (1985) - 25 grams of spent heap material was placed in 50
millimeters of 20 percent NaOH solution and allowed to mix until
delivered to the laboratory which was 12 to 24 hours later;
solution was then analyzed for free cyanide.
The actual data from these examples on cyanide concentrations in spent
heap leach piles is presented in the section, Cyanide in Spent Leach
Piles.
Problems Associated with Analyses
Problems can occur with sample preservation for water samples
containing solids. A clear, filtered sample preserved by the addition
of sodium hydroxide to a pH of 12 and stored in the dark at 4° C (40°
F) will be stable for at least two weeks (Huiatt et al., 1983). There
is, however, no guaranteed method of preservation when solids are
present (Conn, 1981). Samples with solids can be filtered and pre-
served or analyzed immediately. If a sample is known to contain
sulfides, these should be removed by precipitation with lead carbonate
before raising the pH for preservation.
There are many potential sources of interference in analytical
determinations for cyanide including sulfides, oxidizing materials,
thiocyanates, nitrate-nitrite, carbonate-bicarbonate, metal cations,
aldehydes, fatty acids, and potential cyanide-forming materials. ASTM
(1981) states that it is beyond their scope to describe procedures for
overcoming all the interferences that may be encountered.
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Some other problems that have been noted in the literature is that
the cyanide ion-selective electrode can be attacked by cyanide solu-
tions which causes inaccurate results (Frant, et al., 1972). Sulfide
also causes problems by deactivating the surface of the electrode.
ENVIRONMENTAL FATE OF CYANIDE
Cyanide is a very reactive and relatively short-lived contaminant
unlike many pollutants which may enter the environment. Research work
on natural destructive mechanisms and rate of degradation for cyanide
in the environment has begun recently. This section will focus on the
transformation and degradation process for free cyanide, simple cya-
nides, complex cyanides, and cyanogenic glycosides thought to be most
significant to the environmental aspects of a mining operation, and
will conclude with a discussion of the factors influencing the mobility
of cyanide in surface water, ground water, and soils.
Free Cyanide Transformation and Degradation Processes
Volatilization
The most important mechanism in the natural degradation of cyanide
in water is recognized as volatilization of HCN (Simovic et al., 1985).
As discussed above, molecular HCN is the dominant species of cyanide at
pH values below 9.36. Since molecular HCN has a high vapor pressure,
it can readily be volatilized to the atmosphere. Volatilization of HCN
was found to be influenced by pH, temperature, interfacial surface
area, and concentration (Dodge and Zabbon, 1952). Stripping coeffeci-
ents were greatly reduced in stagnant solutions compared to agitated
solutions since the process became dependent on molecular diffusion.
The Chester Engineers (1977) studied dilute cyanide solutions in the
range of 0.1 to 0.5 mg/1. The volatilization rate was O.OA kg-mole/-
2 ?
hr-m -atm (0.009 Ib-mole/hr-ft -atm) in still waters, which is equiva-
2
lent to the volatilization of 0.23 milligram CN/m -hr (0.021 milligram
2
CN/ft -hr) from a 0.5 mg/1 cyanide solution at room temperature.
Volatilization rates in agitated waters were up to three times as fast.
295
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Palaty and Horokova-Jakubu (1959) examined several factors, pH,
temperature, solution depth, presence or absence of aeration and the
rate of aeration, which affect HCN removal. The experiment involved
HCN removal from an unbuffered, synthetic simple cyanide solution (KGN)
at relatively low concentrations (10-50 mg/1 CM) over a period of 11
days. The HCN removal rate increased with decreasing pH down to 5; an
order of magnitude difference in the rates of HCN removal existed
between aerated and nonaerated solutions; and a temperature increase of
10° C (50° F) from 0.8 to 11° C (33 to 52° F) caused the HCN removal
rate to increase by greater than 40 percent.
Broderius (1977) conducted experiments on the volatilization of
cyanide from natural water using concentrations of cyanide from 25 to
200 ug/1. The concentrations of cyanide in the water were measured
during a 6-hour period, from which half lives of 8.8 to 55.5 hours were
calculated for HCN disappearance. Disappearance of HCN became negli-
gable when the samples were sealed and closed off from the atmosphere.
Simovic et al. (1985) studied the rate of cyanide degradation from
a NaCN solution as well as from solutions containing a single metal
cyanide complex and mixtures of metal cyanide complexes. Data from the
solutions containing metal cyanide complexes and metal complex mixtures
will be presented in the following section, Complex Cyanide Transforma-
tion and Degradation Processes. The initial total cyanide concentra-
tion for the NaCN solution at 4° C (40° F) was 200 mg/1. Air was
bubbled through the solution and the solution was exposed to ultra-
violet light. A phosphate buffer was added to maintain a constant pH
of 7.0. The total cyanide concentration decayed to less than 1 mg/1
after about 230 hours (9.6 days). The decay rate was initially much
higher during the first 80 hours (2.1 mg/1 per hour).
Reaction of Cyanide to Formate and Ammonia
Cyanide in water reacts to form ammonia and formate ions. Reac-
tion products from an acidic cyanide solution are formic acid and
ammonium salts and from a basic solution are formate salts and volatile
ammonia. Reaction of HCN in strongly acidic solutions (pH <1) was
296
-------
found to proceed with half-lives ranging from 10 to 1000 hours (Kreible
and McNally, 1929). The rate constants for the reaction of cyanide ion
_n _i _/- _ I
under alkaline conditions range from 2 x 10 sec to 2 x 10 sec
at temperatures between 33 and 65° C (91 and 150° F) (Wiegand and
Tremelling, 1972).
Oxidation
Direct oxidation of cyanide to cyanate (CNO ) requires mineralogi-
cal, biochemical or photochemical catalysis. The reaction is:
20x1"* _i_ n CataJ.ySlS 0 OXT/-\~" /c\
CN + 0« •? 2 CNO (5)
Another route for oxidation is by hydrolysis to HCN and subsequent
oxidation:
2 HCN + 02 > 2 HCNO (6)
In water cyanic acid (HCNO) can hydrolyze to produce cyanate (CNO ).
Hendrickson and Daignault (1973) have shown that cyanic acid can be
hydrolyzed to carbon dioxide and ammonia. The hydrolysis reaction is:
HCNO + H20 = NH3 + C02 (7)
This reaction is pH dependent, and occurs at a pH up to 8.5, but is
greatly accelerated at lower pH values. Further oxidation of ammonia
would form nitrate.
According to Schmidt et al. (1981) oxidation processes may have
accounted for about 11 percent of the decrease in cyanide from a
relatively shallow holding pond for mill cyanide process solutions over
a six month period during the warm season.
Complexation with Metallic Ions
Some 28 elements are capable of forming 72 possible metal cyanide
complexes (Ford-Smith, 1964). The relative stabilities of some of the
common cyanide complexes in water are given in Table B-2. The stronger
or more stable the cyanide complex, the less free cyanide ion required
to maintain it in solution and the less readily it dissociates to yield
cyanide ions.
297
-------
Term
TABLE B-2
RELATIVE STABILITIES OF SOME CYANIDE COMPOUNDS
AND COMPLEXES IN WATER
Examples of Cyanides in
Processing Solutions
1. Free Cyanide
2. Simple Compounds
a) readily soluble
b) relatively insoluble
3. Weak Complexes
4. Moderately Strong
Complexes
5. Strong Complexes
CN , HCN
NaCN, KCN, Ca(CN) , Hg(CN)
Zn(CN)2, CuCN, N1(CN)2, AgCN
~, Cd(CN)~,
Cu(CN)~,
2", N1(CN)J~,
, Au(CN)
Source: Adapted from Scott and Ingles, 1981.
298
-------
The dissociation of a complex cyanide ion involves a number of
intermediate reactions, some of which may be rate limiting steps. At a
given temperature, pH and the concentration of the complex ion influ-
ence the dissociation rate (Broderius, 1973). Rates of dissociation
generally increase with either decreasing pH or decreasing total
cyanide concentration. Dissociation of metal cyanide complex ions will
be discussed further in the section, Dissocation of Metal Cyanide
Complex Ions.
Biological Degradation
Biological destruction appears to be a significant means of reduc-
ing cyanide concentration. Numerous studies have shown that many
bacteria, fungi, and algae are capable of utilizing cyanides, con-
verting cyanide to carbon dioxide and ammonia. Biochemical degradation
of cyanide may occur under both aerobic and anaerobic conditions over a
wide pH range (Towill et al., 1978). Under aerobic conditions cyanide
decomposes to carbon dioxide and ammonia biochemically as shown by
either in equation (5) or (6), and equation (7). Cyanide decomposes to
thiocyanate (SCN ) under anaerobic conditions as shown:
HCN + S2~ = HSCN (8)
Thiocyanate may hydrolyze to produce hydrogen sulfide, carbon dioxide
and ammonia. Schmidt et al. (1981) suggests the general pathways for
anaerobic decomposition are as follows:
HCN + S2~ = HCNS (9)
HCNS + 2H20 = H2S + C02 + NH3 (10)
Higher plants and animals have the capacity to metabolize sublethal
doses of administered cyanide to thiocyanate (Towill et al., 1978).
Activated sludge treatment can result in virtually complete removal of
cyanide (Ludzack and Schaffer, 1962; Kostenbalder and Flecksteiner,
1969), but Raef et al., (1977b) thought that most of the loss of
cyanide in such systems is due to stripping (volatilization).
299
-------
Conversion to Thiocyanate
2— 2—
If sulfide (S ) or thiosulfate (S203 ) is present in the envi-
ronment, cyanide can react to form thiocyanate (SCN ). This chemical
process would occur where sulfide minerals are oxidizing. Metal
thiocyanate complexes may be formed but the formation potential for
metal cyanide complexes is much greater then for metal thiocyanate
complexes. If free cyanide is absent, than metal thiocyanate complexes
will form. Many of metal thiocyanate complexes found in ore processing
solutions are insoluble. This process may play a role in removing some
cyanide and metals from solution.
Sorptlon
Sorption of free cyanide, as well as complexed cyanides, to clays
(Cruz et al, 1974; Schenk and Wilke, 1984), soils (Alesii and Fuller,
1976; Fuller, 1985), sludge (Raef et al, 1977a) and plant debris
(Schenk and Wilke, 1984) occurs to a small extent.
Simple Cyanide Transformation and Degradation Process
The relative solubility of several simple cyanides is shown in
Table B-2. The soluble compounds can readily release free cyanide,
which may be subjected to the degradation processes described above.
However, Zn(CN)2, CaCN, Ni(CN)2, and AgCN are relatively insoluble in
water.
Complex Cyanide Transformation and Degradation Processes
Solubilities of Complex Cyanides Salts
The solubilities of iron cyanide salts are listed in Table B-3.
Most of these compounds are relatively insoluble. If an iron cyanide
salt dissolves, the products are an alkali or heavy metal ion and
either a ferrocyanide or ferricyanide complex, which are strong com-
plexes. The dissociation of metal cyanide complexes such as ferro-
cyanide and ferricyanide is discussed below.
300
-------
TABLE B-3
SOLUBILITIES OF FERROCYANIDE AND FERRICYANIDE SALTS
Formula
(NH4)3Fe(CN)6
Name
Ammonium Ferricyanide
Ammonium Ferrocyanide
Barium Ferrocyanide
Cadmium Ferrocyanide
Calcium Ferrocyanide
Cobalt Ferricyanide
Cobalt Ferrocyanide
Copper (I) Ferricyanide
Copper (II) Ferricyanide Cu3(Fe(CN)6)2'14H20 insoluble
Ba9Fe(CN),,6H00
/ o /
Cd2Fe(CN)6:xH20
Ca0Fe(CN),-12H00
/ o L
Co3(Fe(CN)6)_2
Co2Fe(CN)6-xH20
Cu-Fe(CN),
j o
Solubility (g/1)
very soluble
soluble
1.7 (15°C)
insoluble
868 (25°C)
insoluble
insoluble
insoluble
a/
Cu0Fe(CN),-xH00
i O i
Fe3(Fe(CN)6)2
Fe Fe(CN),
Copper (II) Ferrocyanide
Iron (II) Ferricyanide
Iron (III) Ferricyanide
Iron (II) Ferrocyanide
Iron (III) Ferrocyanide
Lead Ferricyanide
Magnesium Ferrocyanide
Manganese (II) Ferrocyanide Mn2Fe(CN), •
Nickel Ferrocyanide
Potassium Ferricyanide
Potassium Ferrocyanide
Silver Ferricyanide
Silver Ferrocyanide
insoluble
Insoluble
insoluble
-4 b/
Fe2 Fe(CN)6
Fe, (Fe(CN),), 2.5 x 10
4 O J
Pb3 (Fe(CN)6)2 -5H20 slightly soluble
Mg2Fe(CN)6 12H20 330g
insoluble
insoluble
330 (4°C)
278 (12°C)
Ni2Fe(CN)6'xH20
K3Fe(CN)6
K.Fe(CN),-3H_0
4 fa 2.
Ag3Fe(CN)6
Ag4Fe(CN)6-H20
(Continued)
0.00066 (20°C)
insoluble
301
-------
Name
Sodium Ferricyanide
Sodium Ferrocyanide
Strontium Ferrocyanide
Thallium Ferrocyanide
Tin (II) Ferricyanide
Tin (II) Ferrocyanide
Tin (IV) Ferrocyanide
Zinc Ferrocyanide
Zinc Ferricyanide
Zinc Ferrocyanide
Source: Weast, 1969
a/
TABLE B-3 (Continued)
Formula
Na,Fe(CN),°H00
J D I
Na4Fe(CN)6 -
Sr2Fe(CN)6 -
Tl4Fe(CN)6 -2H20
Sn3 (Fe(CN)6)2
Sn0Fe(CN),
/ D
SnFe(CN),
o
Zn2 Fe(CN)6
Zn2 (Fe(CN)6)2
Zn3 (Fe(CN)6)2
Solubility (g/1)
189 (0°C)
318.5 (20°C)
500
3.7 (18°C)
insoluble
insoluble
insoluble
a/
insoluble
2.6 x 10
2.2 x 10
-5b/
-5b/
b/
Source unless otherwise noted is from Weast , 1969.
Source: Mezey and Neuendort, 1981.
302
-------
Dissociation of Metal Cyanide Complex Ions
A stability constant is a measure of the affinity or tightness of
the binding of the complex between the cyanide radical and a metal.
The reaction between a metal ion and cyanide to form a metal cyanide
complex is
M7+ + x(CN)~ = M(CN)x (x"y>- (11)
where M = metal with valence y; and
x = number of cyanide groups in the complex.
The stability constant or the inverse of the stability constant, the
dissociation constant, is expressed as follows:
K^ = [M(CN)x(x"y)" ] = 1 (12)
[My+] [CNX~] Kd
where K = stability constant;
s
K, = dissociation constant; and
[ ] = concentration units in moles per liter.
The values for the stability constants for metal cyanide complex ions
are shown in Table B-A.
In a solution containing different metals where more than one
complex can form, a cumulative or gross constant, BH, is used to
describe the reactions between the metals and cyanide:
M + n(CN) = M(CN)n
The cumulative constant, B , is expressed as follows:
B = [M(CN)n]
[M] [CN]
where the concentration units, [ ], are moles per liter.
The cumulative constant for specific metals can be quantified by the
results of potentiometric titrations conducted both in the presence of
and absence of the metal. Cumulative constants for individual metal
ions are presented in Table B-5. The Bfl values indicate the relative
303
-------
TABLE B-4
STABILITY CONSTANTS OF METAL-CYANIDE COMPLEX IONS
COMPLEX ION
Cr(CN)
Cr(CN)
Fe(CN)
Fe(CN)
Co(CN)
Pt(CN),
Cu(CN),
4
Cu(CN).
Cu(CN)^
Ag(CN)
Ag(CN)
Au(CN),
Au(CN)^
Zn(CN)^
Cd(CN)^
Hg(CN),
3-
4-
4-
4-
4-
2-
2-
2-
2-
2-
2-
3
2-
2-
2-
2-
STABILITY CONSTANT
a/
10
33
10
21
10
35.4
10
47 b/
10
50
10
30
10
42
10
40
10
23.9
10
29.2
10
30.7
10
20.4
10
21.9
io37
85
10 (estimate)
10
21
10
19
10
39
a/
b/
Source unless otherwise noted is from Sharpe, 1976.
Source: Broderius, 1973.
304
-------
TABLE B-5
CUMULATIVE CONSTANTS, Bn, FOR VARIOUS METALS
FOUND IN PRECIOUS METAL ORES
Metal
Cadmium
Cobalt
Cobalt
Copper
Gold
Gold
Lead
Mercury
Nickel
Silver
Zinc
Valence
+2
+2
+3
+1
+1
+3
+2
+2
+2
+1
+2
a a'
n
4
6
6
4
2
4
4
4
4
4
4
Log (10)
of B
16.85
19.09
64
27.3
47.5
56
10.3
41.4
31
21.1
16.9
Log (10)
of [CN]
-1.6
-1.5
-9.0
-4.3
-18.6
-11.4
0
-7.8
-5.2
-2.7
-1.7
a' an = number of cyanide molecules in the metal-cyanide complex.
Source: Milligan, 1985b.
305
-------
strength of the metal cyanide complex. To get an idea of how much
cyanide in solution is needed to form a specific metal cyanide complex,
Milligan (1985b) assumed a cyanide-metal complex to metal ratio equal
to 2.0 x 10 , and then solved for free cyanide content. Lead, for
example, requires a free cyanide content of 1 mole per liter, while all
other metals (Table B-5) would be dissolved and leached from the ore
when mixed with smaller quantities of free cyanide. Certain minerals
containing these metals in the ore may be more stable than the cyanide
complex, and therefore the metal cyanide complex may not form.
The equations for cumulative constant or dissociation constant can
be combined with the equation for dissociation of hydrogen cyanide to
calculate equilibrium hydrogen cyanide concentration at given pH values
and initial concentrations of the metal complex. A decrease in pH
accelerates the reaction as does a decrease of initial concentration.
The rate of dissociation of metal cyanide complexes is also an
important factor. The dissociation of a synthetic solution of single
metal cyanide complexes (Cu, Zn, Ni, and Fe) was studied by Simovic et
al. (1985). The test solutions (initially 200 mg/1 total cyanide) were
aerated, illuminated with ultraviolet light, and maintained at pH 7
(phosphate buffer). There was an initial rapid decrease in the total
cyanide concentrations within the first 48 to 72 hours, which was
attributed to volatilization of hydrogen cyanide. The total cyanide
concentration continued to decline, but at a slower rate. The metal
cyanide complex decay coefficient was determined for the two different
temperatures tested (Table B-6). The half life for each metal cyanide
complex was calculated from this data. Zinc cyanide complex had the
fastest decay rate, followed by copper, iron, and nickel complexes.
Only the decay rate of iron cyanide complex was affected by ultraviolet
light (which is discussed in the next section). Other data from these
studies, showed that residual total cyanide concentrations decreased to
less than 1 mg/1 within four days for the zinc cyanide complex solution
and within 12 days for the copper cyanide complex solution (Simovic and
306
-------
TABLE B-6
DEGRADATION OF METAL CYANIDE COMPLEXES IN
PHOSPHATE BUFFER AT pH 7a/
Zn(CN)42"
Cu(CN)32-
Fe(CN)63~
Ni(CN) 2~
kn x 102
(4 °c)
(hr"1)
1.78
0.29
0.14
0.04
t1/2b/
(4 °C)
(days)
1.6
9.9
20.6
72.1
k, x 102
(20 °C)
(hr'1)
4.49
0.75
0.47
0.09
t1/2b/
(20 °C)
(days)
0.64
3.8
6.1
32.0
a/
b/
Initial concentration is 200 mg/1. Adapted and modified from
Siraovic et al., 1985.
Half-lives were calculated from the rate constants (Versar Inc.,
1986).
307
-------
Snodgrass, 1985). The total cyanide concentration of the iron cyanide
complex solution was 10 mg/1 after 15 days. The decay rate of the
nickel cyanide complex solution was so slow that the concentration had
not decreased to less than 30 mg/1 even after nine days.
Photochemical Degradation
4- 3-
The iron cyanide complexes, Fe(CN>6 and Fe(CN>6 , in water
produce free HCN from photochemical degradation by sunlight (Broderius
and Smith, 1980). The lower the concentration of the iron complex
ions, the faster the rate of photodegradation. The amount of HCN
formed will increase with increasing concentration of the photolabile
iron cyanide. The maximum amount of total cyanide (complexed cyanide)
converted to free cyanide was 85 percent and 49 percent for Fe(CN),
3_
and Fe(CN), , respectively. Photodegradation rates decrease rapidly
with depth in natural water systems. The ultraviolet radiation from
the midday sun on a Minnesota lake during summer accelerated the
decomposition of ferricyanide to a resultant half life of 20 minutes
(Broderius, 1973). During the fall the half-life increased to 50
minutes. Simovic et al. (1985) research with degradation of metal
cyanide solutions showed that of the variables, temperature, aeration,
and presence of ultraviolet light, ultraviolet light had the largest
effect on the iron cyanide solution. The results of tests by both
Moggi et al. (1966) and Kelada et al. (1985) showed that cobalt III
cyanide complex also is broken down by ultraviolet radiation.
Cyanogenic Glycosides Transformation and Degradation Processes
Cyanide may be released from cyanogenic glycosides subjected to
hydrolysis in vitro by dilute mineral acids or in vivo by enzymes. One
of the best known cyanogenic glycosides, amygdalin, occurs in the
Rosaceae (rose) family. The hydrolysis of amygdalin is shown in Figure
B-2. The HCN released from cyanogenic glycosides may undergo any of
transformation or degradation processes described above for free
cyanide.
308
-------
FIGURE B- 2
THE HYDROLYSIS OF A CYANOGENIC GLYCOSIDE,AMYGDALIN
AMYGDALIN
HCN
CHO
BENZALOEHYDE
(MODIFIED FROM FULLER. i9es )
H20
+ H2O
MANDELONITRILE
C6Hi206
-------
Mobility of Cyanide in Surface Water
Figure B-3 summarizes cyanide reactions in surface water. The
mobility of cyanide in surface water will be dependent on a large
number of factors, including pH, temperature, concentration and type of
metals and resulting metal cyanide complexes, properties of the water
body (depth, surface area, amount of turbulence or aeration), presence
of ultraviolet light, and quantities and forms of transported organic
and inorganic suspended matter, and interchange with sediment. The
different mechanisms for cyanide degradation have been discussed above;
each location will have its own set of factors which may tend to
release or immobilize cyanide. Generally, free cyanide ion will be
more mobile in waters with higher pH, lower temperature, lower levels
of metals, organic and inorganic suspended matter, and little inter-
action with sediment. The properties of a water body that would
promote higher mobility of cyanide are stagnant, deep conditions with
little surface area. Cyanide will more readily volatilize in highly
aerated waters with lower pH's. Free cyanide will be less mobile in
waters where there are higher concentrations of metals, sulfide, and
organic and inorganic matter. If iron or cobalt complexes are present,
then the presence of ultraviolet light may be a factor in increasing
the mobility of cyanide.
No predictive models have been developed for the mobility of
cyanide in streams. However, several models have been developed to
predict the natural degradation of cyanide in gold mining effluents
(refer to the section, Degradation of Cyanide at Heap leach Opera-
tions).
Mobility of Cyanide in Ground Water
The mobility of cyanide in ground water is also dependent on many
factors such as pH, temperature, concentration and type of metals
present and subsequent formation of metal cyanide complexes, amount of
aeration, and interaction with soil or rock particles. Volatilization
rates of HCN from ground water are probably reduced compared to surface
water. Volatilization, however, may be an important process in the
310
-------
FIGURE B-3
CYANIDE REACTIONS IN SURFACE WATER
DIFFUSION
^DISPERSION
ULTRAVIOLET
LIGHT
H,O
r
NH34HC03
+ F« (CN)6 4' OH~/CN~ R«ducUon
CN- + F«(CN)*'.,UVU«""»F.- 5
0 O
ui "C
til I, i
ui
DC (0
U. UJ
IL X
Sy
ss
3o
U.U
V
1
/nr/*r —l s.n\\tnt
_^ \HMCM)jy
8ORPTION ^T
\
, 8ORPTION
SUSPENDED MATTER
j
SEDIMENTATIO
'
M/RESUSPENSION
'
' TO BIOLOQICAL OXIDATION z£
S2
"s
2
tg
• ^
«:o
"K
UjU-
s»
Sui
X
U-m
O-i
x|
3o
CTo
DEPOSITED SEDIMENTS
RELEASE OF FREE CYANIDE AND/OR METAL CYANIDE
COMPLEXES TO INTERSTITIAL WATERS
ANAEROBIC BIOLOGICAL ACTIVITY
HCN/CN
SOURCE: MODIFIED AFTER MUDDER . 1866
HSCN
H20
*-NH3
HCOONH4 _
CH4 + NH3
-------
vadose zone. Several researchers have showed that stripping coeffic-
ients for stagnant cyanide solutions were greatly reduced compared to
agitated solutions, since the process becomes dependent on molecular
diffusion. On the other hand, processes that tend to tie up cyanide
such as sorption and complexation may be more important processes for
ground water than surface water. Ground water flow is generally much
slower than surface water which allows more time for interaction of the
water with soil or rock minerals. Reaction of cyanide to ammonia and
formate ions may also be an important process to remove cyanide from
ground water. The other factors such as pH and temperature are also
important and vary in the same way as for surface water; that is
cyanide is more mobile at higher pH values and lower temperatures.
Iron and cobalt cyanide complexes will not undergo photochemical
degradation in ground water; however, if ground water is discharged to
surface water this process may become important.
Mobility of Cyanide in Soils
The mobility of cyanide in soils is largely dependent on soil clay
content, depth of soil, content of hydrous oxides of iron, manganese,
aluminum and other metals, pH, presence of aerobic or anaerobic condi-
tions, and presence of soil organic matter (Fuller, 1985). Alesii and
Fuller (1976) and Fuller (1985) found cyanide in water as Fe(CN)6 ~ and
CN to be very mobile in soils, whereas cyanide as KCN in natural
landfill leachate (which contained metals) was less mobile in soils.
During this experiment, the anaerobic state of the soil columns inhibi-
ted microbial degradation of cyanide. The limit for effective anaero-
bic degradation of cyanide was found to be 2 mg/1 in studies of a
sewage wastestream (Coburn, 1949), which is considerably lower than 100
mg/1 used In the experiment. The high clay content soil retained more
ferricyanide than the sandier soil of similar pH. Ferricyanide was
retained the most in soils having a low pH, which was explained by the
clay surface having a high percentage of positive exchange sites. The
KCN solution leached most rapidly In the soil having the lowest pH.
312
-------
Cyanide was retained most by soils having a high concentration of
hydrous oxides. Mobility of cyanides is greatest in soil at high pH
and low clay content.
Cyanide-yielding compounds rapidly ammonify and nitrify in the
same soils under aerobic field conditions (Fuller, 1985). In fact,
despite regular use of pesticides and fertilizers containing low levels
of cyanides or cyanide-yielding compounds, cyanides do not accumulate
in the soil.
Wharf Resources Inc. (1982) conducted tests of effluent from
cyanide solutions applied to soil columns containing native soil from
the Annie Creek Mine area in the Black Hills, South Dakota (Table B-7).
Results from the 150 mg/1 total cyanide solution showed that both total
and free cyanide were reduced to less than half the concentration of
the originally applied solutions during the test and continued to
decline over the next 6 weeks.
Research is being conducted by DuPont on soil collected from below
heap leach pads at two mining operations (F. DeVries, Dupont Company,
personal communication, 1986). Besides describing soil mineralogy,
they are conducting two types of tests including 1) stirred reaction
with cyanide, and 2) column tests with cyanide. Data from these tests
will be incorporated into a model used to predict the mobility of
cyanide in soils.
CYANIDE CHEMISTRY OF HEAP LEACH OPERATIONS
Cyanidation
In the cyanidation process, precious metals are leached from ores
with a cyanide solution. In most mineral leaching operations in the
United States, the leaching solution is prepared from sodium cyanide.
The sodium cyanide in solution will dissociate to sodium and cyanide
ion as discussed above (equation 3). The optimum pH process solution
for leaching purposes is 10.3 (Barsky et al., 1962), so cyanide ion
remains predominant (refer to Figure B-l). The leaching solution
contains sodium cyanide at a concentration of 0.05 percent (equivalent
313
-------
TABLE B-7
RESULTS OF TESTS WITH CYANIDE SOLUTIONS (in mg/1) ADDED TO ,
COLUMNS CONTAINING NATIVE SOIL FROM THE AREA OF ANNIE CREEK MINE, SD
Test 4-SS
Test 5-SS
Test Conditions
Influent solution
Effluent
Effluent
Effluent following
fresh-water flush
(Nominally 150 mg/1)
Date Free CN Total CN
8/19/82
8/17
8/18
10/4
36.5
4.5
17
2.4
149
65
46.5
29
(Nominally 1 mg/1)
Date Free CN Total CN
8/25 - 8/27/82
8/26
8/27
10/4
1.0
<0.01
<0.01
<0.05
1.0
0.03
<0.01
<0.05
Source: Wharf Resources Inc., 1982.
a/ 22
Cyanide solutions added to soil columns at about 20 1/min/m (0.5 gal/min/ft ) for 3 days.
-------
to about 250 mg/1 free cyanide) Chamberlain and Pojar (1984). At some
operations, the cyanide concentration is much higher (600 to 1000 mg/1)
for the first few days of leaching and subsequently drops to approxi-
mately 200 mg/1. The rate of dissolution depends on cyanide concen-
tration, oxygen availability, temperature and solution pH. The effic-
iency of leaching depends on the type of ore. Ore that contains clean,
free fine-sized gold particles, little clay content, and no cyanicide
impurities that may destroy cyanide or inhibit its reaction provides
the most efficient leaching situation. Since the reaction is tempera-
ture sensitive, the leaching rate of precious metals during colder
conditions may be only 70 percent of the leaching rate during summer
operating conditions (Milligan, 1985b). Examples of cyanicides are
sulfide and ferrous or ferric iron. Details of two example cyanide
leaching operations are provided in Appendix A.
The reaction for dissolution of gold and complexation with cyanide
is (Heinen et al., 1978):
2Au + 4CN~ + 02 + 2H20 = 2Au(CN)2~ + H^ + 2 OH~ (15)
A lesser amount of gold is solubilized as shown in the Eisner's equa-
tion:
4Au + 8CN~ + 02 + 2H20 = 4Au(CN)2~ + 4 OH~ (16)
The equations for silver dissolution are similar.
Other metal cyanide complexes may be present in the leaching
solution depending on the various metals and their forms in the ore.
If the metals in the ore are in the form of compounds less stable than
the cyanide complex and the metals are exposed to the leaching solu-
tion, then the rate of metal dissolution by cyanide increases directly
in proportion to the free cyanide concentration present in the solu-
tion. Eventually, a limit is reached at the maximum dissolution rate
of the metal cyanide complex; further increases in the free cyanide
concentration may have a slight retarding effect on the dissolution
rate of the complex (Milligan, 1985b).
315
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The pregnant solution (process solution containing complexed
precious metals) is processed through carbon adsorption columns and/or
zinc precipitation units in order to recover the gold and silver. In
the carbon process the metal cyanide complexes adsorb to the carbon
surface. When the carbon columns reach a certain loading capacity, the
metals are stripped from the carbon with an alcohol-caustic-cyanide
solution. The gold and silver from this solution is removed by elec-
trowinning.
Alternatively, zinc dust is added to the pregnant solution to
precipitate the gold and silver cyanide complexes in the zinc precipi-
tation process. Gold and silver precipitation are improved by adding
lead acetate or lead nitrate to the solution. The precipitation
reaction for gold is:
NaAu(CN)2 + 2NaCN + Zn + H_0 = Na_Zn (CN), + Au + H+ + NaOH (17)
The solution containing the precipitate is filtered and dried for
smelting.
Cyanide in Spent Leach Piles
Very little data exists on the amounts and forms of cyanide in
spent leach piles. It is difficult to compare the limited data that
exists since researchers are not using a standardized method of samp-
ling the spent ore heaps or leaching the solid sample before analysis.
The cyanide content and forms in spent leach piles will depend on the
ore mineralogy, ore pH, heap permeability, the thickness of the heap,
cyanide concentration in process solution, solubility and dissociation
rate of metal cyanide complexes, temperature, the type and application
of rinsing solutions, and the rate of release of cyanide from the pile.
Volatilization is probably the most important process for the removal
of cyanide from spent ore heaps after the heaps have been rinsed.
Atmospheric sampling data are not available for the low level release
of HCN from spent leach piles.
316
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Research is currently being conducted by J. Hendrix (University of
Nevada, personal communication, 1986) on cyanide in spent leach piles.
His research consists of 1) experimentation with a leaching column
containing ore in the laboratory and 2) collection of samples (repre-
sentative sampling on a grid) from spent leach piles. Dr. Hendrix is
also developing analytical methods to determine the amounts of specific
metal cyanide complexes present.
Engelhardt (1985) and Milligan (1985a) studied the decay of
cyanide after the heap leaching of some tailings (15 percent plus-100
mesh) that were formerly processed for lead, zinc, and silver (sulfide
and oxide circuit) in the 1940's and 1950's. The location of this
operation was in a desert area. Approximately 5,400 kilograms (12,000
pounds) or 11.5 percent of the cyanide remained in the spent heaps,
after rinsing the 76,000 metric tons (84,000 short tons) of ore. A
time-series study was initiated to examine the natural dissipation of
cyanide levels in the ore. Samples were collected from 11 areas on the
heap by driving a 3.8 centimeters (1.5 inch) pipe through the heap to
the pad. Samples were agitated for one hour with distilled water and
the slurry was filtered to recover the solution. After adjusting the
pH to 12.0, the samples were analyzed for free cyanide. Sampling was
conducted in January (3 months after the leaching process ceased),
March, June, and September, 1983 and 6 months later in March, 1984.
The pH in the heaps fell from 10.5 at the cessation of the operation to
approximately 9 in late 1984. Results showing substantial decreases in
free cyanide concentrations between the initial and final sampling
periods are presented in Table B-8. Total cyanide data was not
reported but it is stated that total cyanide was almost the same as
free cyanide implying that there are no significant amounts of complex-
es. The data showed little correlation of cyanide concentration with
depth. Based on these data (relatively few data points), the authors
stated that at the present rate of degradation, it would take approxi-
mtely four years for the cyanide concentration of the spent heap pile
to decay to 1 mg/kg.
317
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TABLE B-8
FREE CYANIDE CONCENTRATIONS IN ELEVEN
LOCATIONS IN THE DARWIN HEAP
Percent
Darwin
ID No.
Q3S2
Q3S3
Q3S4
Q6S1
Q6S2
Q6S3
Q6S4
Heap
No.
1
2
3
4
5
6
7
Moisture
Jan 83
14.6
14.0
16.4
14.7
14.6
15.9
15.2
Mar 84
14.6
13.0
15.5
14.6
12.5
14.3
12.0
Q9S1
Q9S2
Q9S3
Q9S4
8
9
10
11
14.3
14.8
14.5
13.4
12.2
11.9
11.8
11.4
Free Cyanide
(rag/kg)
Jan 83 Jan 84
102.6
118.8
196.2
144.8
87.2
155.0
91.4
146.8
34.7
8.5
7.7
<6.8
13.4
23.8
22.2
20.0
28.4
<6.8
37.5
<6.8
<6.8
<6.8
Percent Loss of
Free Cyanide During
15 Months
93.4
88.
87.
84.7
77.1
81.7
92.6
74.5
80.4
21.2
16.9
Source: Engelhardt, 1985; Milligan, 1985a.
318
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Research on the destruction of cyanide in the leached heaps was
conducted at the Stibnite Mine in Idaho (Stotts, 1985). After leaching
was completed, a solution containing chlorine and lime was sprayed on
the heaps. The effluent from the rinsing was recycled through the
neutralization system until it contained a free cyanide concentration
of 0.2 mg/1. After a 0.2 mg/1 concentration was reached, hourly
testing of the solution was done over a period of 24 hours. If the 24
hour average free cyanide concentration did not exceed 0.2 mg/1 and no
single sample exceeded 1.0 mg/1, then the heap was environmentally
suitable for disposal as required by the operator's agreement with the
U.S. Forest Service. If, however, the 24 hour test failed to meet
these requirements, the entire procedure was repeated. An analysis for
a sample from the chlorine pond (rinsing solution) is given in Table
B-9. This table shows the metals associated with the ore at Stibnite,
some of which may form salts of metal cyanide complexes and remain in
the spent ore. After treatment with chlorine, the spent ore was hauled
to an old tailings site and spread out in thin layered lifts of 0.3 to
0.6 meters (1 to 2 feet).
Ten locations in the spent ore were sampled at 15 to 30 centi-
meters (6 to 12 inches) below the surface at one, five, and ten day
intervals. Cyanide was analyzed from the leachate produced from the
mixing of 25 grams of ore placed in 50 milliliters of cyanide-free
caustic soda (NaOH) solution at 20 percent strength. The ore was
leached for 12 to 24 hours. Results of the time series decay of
cyanide for eight of the samples are shown in Figure B-4. The average
10-day decrease was approximately 50 percent of the content on the
first day, with a range from about 10 percent for the samples with a
very low starting concentration to a high of nearly 80 percent for
samples having a higher starting concentration.
Ray (1985) sampled various heap leach piles in the southeastern
desert of California and found that total cyanide levels were highly
dependent upon the mineral composition of the ore (Table B-10). The
sampling procedure was not described. The total cyanide analysis was
conducted on a 20 gram sample that was subjected to a 24-hour leaching
319
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TABLE B-9
SOLUTION SAMPLE OF CHLORINE POND AT STIBNITE MINE, IDAHO
August 24, 1983
Chloride 1,724 rag/1
Arsenic 0.271 rag/1
Antimony 0.021 mg/1
Calcium 560 mg/1
Copper 0.071 mg/1
Iron 0.590 mg/1
Lead 0.034 rag/1
Mercury 0.357 mg/1
Sodium 135 mg/1
Zinc 0.030 mg/1
Cadmium 0.016 mg/1
Source: Stotts, 1985.
320
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FIGURE B-4
CYANIDE DEGRADATION IN TREATED WASTE
ORE FROM STIBNITE MINE,IDAHO
LU
Q
u
Uj
LU
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
C 2.90
B
1 5 10
DAYS SINCE SPREADING IN THIN LIFTS
NOTE: THE LETTERS (AtoE ) REPRESENT
LOCATIONS. TWO SAMPLES WERE TAKEN
FROM SEVERAL LOCATIONS (A.C.AND D).
THE SOLID AND DASHED LINES ARE FOR
CLARITY.
(MODIFIED FROM STOTTS, 1985)
321
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TABLE B-10
TOTAL CYANIDE CONCENTRATIONS FOR VARIOUS
HEAP LEACH OPERATIONS IN CALIFORNIA
Description of
Ore Samples
Run No.
Samples low in iron
Samples high in iron and copper
Samples high in iron, mined for silver
Samples high in copper
Samples low in cyanicides
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
0.97
0.41
0.24
0.42
0.12
0.27
1.5
0.90
75
34
9.0
17.1
5.9
11.2
105
41
83
91
5.7
0.82
<0.05
<0.05
<0.05
1.0
0.07
<0.05
0.12
0.20
<0.05
<0.05
Source: Ray, 1985.
322
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in the dark using a 1.25 N NaOH solution, filtration, and analysis of
the filtrate by the EPA (1979) distillation/destruction method, follow-
ed by colorimetric measurement.
The California Regional Water Quality Control Board, Colorado
River Basin, Region 7 (1985) use to require a 1.0 mg/kg limit on the
total cyanide found in abandoned heap leach piles. After reviewing the
literature, specifically fish toxicity studies and cyanide environmen-
tal chemistry, they have changed the limit to 10 mg/kg. Their ration-
ale is that because iron is the major metal atom available for complex-
ation, iron cyanides are expected to be the only strong complexes
formed. Other complexes are weaker and can be expecte'd to degrade
readily to cyanide ion. Therefore, the major species to consider in
heap leach piles are iron cyanides and cyanide ion. Since iron cya-
nides are considered to be of low toxicity and have proven to be
generally non-leachable, only cyanide ion content should be considered.
A cyanide level of 0.02 mg/1 was acceptable to the Regional Board and
after multiplying by 100 (their usual practice when accounting for
dilution in the environment), a level of 2.0 mg/1 was obtained. The
analysis of the sample is performed by leaching 1 part solid to 5 parts
liquid; using this ratio and 2.0 mg/1, the acceptable limit for a solid
is 10 mg/kg. Based on this rationale requirements from the Regional
Board, the Mesquite Mine was required to rinse as follows when abandon-
ing heap leach piles: 1) 90 percent of at least 10 samples shall
contain less than 10 mg/1 free cyanide and 2) none of the samples shall
contain more than 20 mg/1 free cyanide.
A sample collected from leached ore (with pH of 8.3) at the
Zortman and Landusky heap in Montana had a concentration of 4.5 mg/kg
for both total cyanide and cyanide amendable to chlorination (ERGO,
1984). The method of analysis was that prescribed by the EPA (1982).
Concentrations of total cyanide and cyanide amendable to chlorination
in the inactive heap leach material (with pH of 8.8) from the Pinson
Mine in Nevada were both less than 2 mg/kg.
323
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The sample extraction or leaching method prior to analysis may
determine the content of cyanide in the sample. Spent heap leach
wastes from Tombstone Silver Mines, Inc. (Arizona) were sampled and 75
grams of sample were leached with 150 milliliters of water and 0.1 gram
of lime (CaO) for 1 hour (Pahlman, 1986). Most of the values were less
than 0.1 mg/1 with a range of less than detectable to 0.40 mg/1. An
assay method from the U.S. Bureau of Mines, in which extraction was
allowed for 12 hours on 40 gram of sample with 200 milliliters of water
and 1 gram of sodium hydroxide, gave cyanide values that were 2 to 10
times greater than the previous method. The range of cyanide concen-
trations was less than 0.25 to 0.86 mg/kg with more than half the
values below the detection limit of 0.25 mg/kg.
Sampling was conducted of the runoff from test heaps at the Annie
Creek Mine (South Dakota) that were neutralized with hypochlorite
followed by water (McGrew, 1985). After the first month (1982) there
was more than a 10-fold decrease in both total cyanide and weak acid
dissociable cyanide with decreases of 300 to 3.4 mg/1 and 300 to 10
mg/1, respectively. Values continued to decrease with a range of 0.2
to 0.01 mg/1 weak acid dissociable cyanide for sampling in December,
1983 to June, 1985. The test heaps were also sampled with depth up to
1.8 meters (6 feet). Of a total of 30 samples analyzed for total
cyanide at 0.3 meter (1 foot) intervals, 21 samples were less than the
detection limit of 0.5 mg/1, five analyses were between 0.5 and 0.6
mg/1, three between 0.6 and 0.7 mg/1, and one was higher than 0.7 mg/1.
Of the 30 samples, for weak acid dissociable cyanide, 28 were below the
detection limit of 0.5 mg/1 and 2 were between 0.5 and 0.6 mg/1.
Samples were also taken of the clay liner directly below the heaps.
Cyanide did not penetrate below a depth of 10 centimeters (4 inches)
based on 23 samples analyzed at 5-centimeter (2-inch) depth intervals.
Of the 23 total cyanide concentrations, only 5 had detectable levels
which ranged from 1.29 to 2.92 mg/1 in the 0- to 5-centimeter (0- to
2-inch) and 5- to 10-centimeter (2- to 4-inch) clay samples. Weak acid
dissociable cyanide was detected in only one sample at 0.83 ppm in a 5
to 10 centimeter (2- to 4-inch) interval.
324
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There also is little information on the content and forms of
cyanide in leachate from spent heap leach piles. As a part of the
study by Engelhardt (1985) and Milligan (1985a) described above, the
entrained solution in the heaps was also sampled for cyanide content.
The moisture content in the first sampling (January, 1983) ranged from
13.5 to 16.4 percent and the final sampling (March, 1984) ranged from
11.4 to 15.5 percent. The average values for the two sampling periods
were 340 rag/1 and 106 mg/1 free cyanide, respectively.
Degradation of Cyanide at Heap leach Operations
During the course of operation and at closure, cyanide in spent
ore piles and process solutions must be rendered harmless. There has
been very little published on the treatment of cyanides in spent ore
piles, while extensive literature exists on the treatment processes for
solutions containing cyanide.
Spent Leach Heap Piles
Upon closure of spent heaps operators are using several different
methods to expedite the destruction of cyanide in the heaps. The
requirements for neutralization vary by state (Table B-ll). Generally,
the rinsing procedure consists of either applying fresh water or an
alkaline solution containing chlorine to the heap. The resulting
effluent is recyled through the heap after the rinseate is treated with
a method to destroy cyanide. This process is repeated until the
cyanide concentration required in the effluent is obtained. Methods
for neutralizing cyanide in water are described in detail below.
Examples of the amounts of cyanide remaining in spent piles after
rinsing were discussed above.
Natural degradation processes including volatilization, photo-
decomposition, oxidation, adsorption, and biodegradation continue to
reduce levels of cyanide in the spent heaps after rinsing. Examples of
some rates of cyanide degradation in spent heaps were discussed above.
325
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TABLE B-ll
State
Arizona
California
UJ
IS3
CT.
Colorado
Idaho
Montana
New Mexico
Nevada
WESTERN STATE REGULATIONS OR GUIDELINES FOR NEUTRALIZATION
OF SPENT HEAP LEACH PILES
Required Cyanide Content of Rinseate
Require the operators to show evidence there is no free cyanide; no recommendations for rinsing
process (J. McCutchan, Arizona State Mine Inspector, personal communication, 1986).
Guidelines vary between Regional Boards. Region 5 - 0.35 mg/1 free cyanide (D. Heiman,
California Regional Quality Control Board - Region 5, personal communication, 1986). Region 6 -
0.2 mg/1 free cyanide or 10 mg/kg total cyanide (M. Watkins, California Regional Water Quality
Control Board - Region 6, personal communication, 1986). Region 7 - 2.0 mg/1 or 10 mg/kg free
cyanide (California Regional Water Quality Control Board, 1985).
Considering developing guidelines. Recommend 2 mg/1 free cyanide; in sensitive areas recommend
0.75 mg/1. Recommend fresh water or hydrogen peroxide for rinsing method (A. Baldridge,
Colorado Mined Land Reclamation Division, personal communication, 1986).
Developing regulations (I. Nautch, Idaho Water Quality Bureau, personal communication,
Requirements for Stibnite (0.2 mg/1 free cyanide); recommend hypochlorlte rinse.
1986).
Developing regulations/guidelines (D. Smith, Montana Department of State Lands, persona
communication, 1986).
Guidelines; 45 kg (100 Ib) sample rinsed can not have more than 100 mg/1 total cyanide (A. Die,
New Mexico Environmental Improvement Division, personal communication, 1986).
Required to rinse with water until pH of rinse water is 8.5 for three consecutive days (H. Var
Drieun, Nevada Division of Environmental Protection, personal communication, 1986).
(Continued)
-------
TABLE B-ll (Continued)
State Required Cyanide Content of Rinseate
Oregon Guidelines of 0.01 mg/1 total cyanide; recommend hypochlorite rinse (K. Ashbaker, Oreg
Department of Environmental Quality, personal communication, 1986).
South Dakota Guidelines for Wharf Resources (0.75 mg/1 total cyanide); currently working on rinsing metl
recommendation (B. Townsend, South Dakota Department of Natural Resources, persoi
communication, 1986).
Utah Guidelines for Mercur Mine (5 mg/1 free cyanide); no recommendations for rinsing method
Dietz, Utah Water Pollution Control, personal communication, 1986).
Washington Developing regulations/guidelines (B. Lingley, Washington Department of Natural Resourc
personal communication, 1986).
Wyoming No regulations or guidelines (C. Bosco, Wyoming Land Quality Division, personal communication,
w 1986).
ISJ
-------
Process Cyanide Solutions
Barren solution should be subject to cyanide destruction upon
closure. In addition, during fall some barren solution may need to be
treated and released (possibly as a land application) in anticipation
of winter precipitation to meet water balance requirements. The
rinsing solution used to neutralize the spent ore heaps will also
require a treatment process. The methods described below are based on
volatilization (natural degradation), oxidation (alkaline chlorination,
hydrogen peroxide, Inco process), and biological processes. The major
treatment processes that are used or may be used at leaching operations
are summarized here; these and other processes are described in more
detail in Huiatt et al. (1983) and Scott (1985).
Natural Degradation. The results of studies of barren and tail-
ings ponds in Canada (Simovic et al., 1985; Schmidt et al., 1981) show
that natural degradation of cyanide occurs with over 90 percent of
cyanide decrease attributed to volatilization of molecular HCN. For
example, the cyanide content of a waste barren pond decreased from 64
mg/1 in March to 0.05 mg/1 in the following August and the pH dropped
from 10.5 to 7.0 (Schmidt et al., 1981). The pH drop was a result of
natural carbonation and the hydrolysis of thiocyanate. Some photode-
composition of ferrocyanides occurred.
A model has been developed to predict the natural degradation of
cyanide in gold mill effluents, specifically barren solution and
tailings pond water (Simovic et al., 1985; Simovic and Snodgrass,
1985). The model utilized the results from the synthetic solutions
described in the section, Dissociation of Metal Cyanide Complex Ions,
and assumed that the decay rate of a metal cyanide complex and subse-
quent volatilization of HCN control the disappearance of total cyanide
from solution, with metal cyanide complex decay being the rate control-
ling factor. The model was used to predict degradation times for
representative wastewater systems at two Canadian gold mills. The
degradation of cyanide from tailings pond water was predicted very
closely, but the model needs further calibration for the barren solu-
tions.
328
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Alkaline Chlorination. The most developed of all the available
methods in regards to background experience, operational simplicity,
control techniques, availability of equipment, and engineering exper-
tise, is alkaline chlorination (Ingles and Scott, 1981). The complete
oxidation of cyanide to nitrogen and bicarbonate requires two stages
(Scott, 1985). In the first stage cyanide undergoes oxidation and
hydrolysis at a minimum pH of 10.5 as shown:
NaCN + C12 — > CNC1 + NaCl (19)
CNC1 + 2NaOH — > NaCNO + NaCl + H20 (20)
During the second stage of the process, cyanate is further oxidized to
nitrogen and bicarbonate at a pH of about 8.5, which can be represented
by the overall reaction:
3C12 + 2NaCNO + 6NaOH — » 2NaHC03 + N2 + 6NaCl + 2H20 (21)
Metal cyanide complexes are oxidized during the first stage of the
process as shown for the zinc cyanide complex:
(22)
Na2Zn(CN)4 + lONaOH + 4C12 — •» ANaCNO + 8NaCl + Zn(OH)2
The alkaline chlorination method destroys free cyanide ion, hydrogen
cyanide, and cyanide from most metal cyanide complexes with the excep-
tion of iron cyanide complexes. Table B-12 presents the advantages and
disadvantages of alkaline chlorination.
Hydrogen Peroxide. The hydrogen peroxide method, which is well
known and widely used in the treatment of effluents from the steel
hardening and other industries, is now being applied to the gold mining
industry. The hydrogen peroxide method is favorable from the environ-
mental view since no toxic by-products are generated nor are additional
chemicals added which may be detrimental to the environment (Knorre and
Griffiths, 1985). In addition, metals are precipitated as hydroxides.
The reaction for the oxidation of cyanide to cyanate is:
CN~ + H0 — > CNO~ + H0 (23)
329
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TABLE B-12
ADVANTAGES AND DISADVANTAGES OF ALKALINE GHLORINATION
ADVANTAGES OF ALKALINE CHLORINATION
1) Very widely-used method, expertise is available.
2) Influent to process already basic.
3) Reactions complete and reasonably rapid.
4) Toxic metals removed.
5) Chlorine readily available in several different forms.
6) Readily adaptable to either continuous or batch operation.
7) Capital outlay relatively low.
8) Good fail-safe control.
9) Easily controlled to first stage of oxidation, if disposal of CNO~
is permitted.
DISADVANTAGES OF ALKALINE CHLORINATION
1) Reagent costs are high, particularly if complete oxidation is
required. Thiocyanate, thio-salts and ammonia are additional
heavy consumers of chlorine.
2) Requires careful control of pH to prevent formation of cyanogen
chloride which is very toxic.
3) Cyanide is not recovered.
4) Hexacyanoferrates are not usually decomposed.
5) Metal content is not recovered.
6) The chloride content of the effluent is increased in direct
proportion to the amount of chlorine added.
7) There is a possibility of forming toxic chlorine derivatives (e.g.
chlorinated organic compounds) which will require further
treatment.
8) Residual excess chlorine can be toxic to aquatic species.
a/ 2-
Clean-up of excess chlorine is readily accomplished with S_0^ or
HJD , but an extra step is needed.
Source: Adapted from Ritcey and McNamara, 1978; cited by Ingles and
Scott, 1981.
330
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The cyanate formed in this reaction hydrolyzes further to form ammonium
and carbonate ions:
CNO~ + 2H20 —» C032~ + NH4+ (24)
The reaction for the precipitation of metals is:
Me(CN)A2~ + 4H202 + 20H~ —> (Me(OH)2N) + 4CNO~ + 4H20 (25)
Complex iron cyanides are too stable to be oxidized but they may be
precipitated by the addition of copper:
2 Cu2+ + Fe(CN)64~ —» (Cu2Fe(CN)6) (26)
The hydrogen peroxide method destroys hydrogen cyanide, cyanide ion,
and cyanide in copper, zinc, and nickel cyanide complexes. If copper
is added, iron cyanide complexes may be precipitated.
Inco Process. This method was originally developed for base metal
mining operations, but is now used by a number of gold mines in Canada.
Oxidation by SO- in air in the presence of a copper catalyst causes the
rapid removal of cyanide and metal cyanide complexes. The overall
reaction is the oxidation of cyanide to cyanate which is described by
the equation:
CN~ + °2 + S02 + H2 = CNO~ + H2S°4 ^27^
Iron cyanide complexes are removed by precipitation as copper or zinc
ferrocyanides. The metals except for iron are precipitated as metal
hydroxides. Thiocyanate is not removed.
Biological Treatment. Homestake Mining Company has recently
developed a biological treatment method for removing cyanide and metal
ions from effluents (Mudder and Whitlock, 1983). An essential require-
ment for successful operation of this process is the ability to blend
mine water at 21 to 29° C (70 to 85° F) with tailings impoundment water
at 1.1 to 21° C (34 to 70° F) to maintain a year round combined waste-
water temperature sufficiently warm at 10 to 18° C (50 to 65° F) to
sustain effective biological process rates. The two stages of the the
methods are 1) bacterial oxidation of cyanide and thiocyanate to carbon
dioxide, sulfate, and ammonia concurrent with the adsorption of metals
331
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by the bacteria and 2) bacterial nitrification of ammonia to nitrate.
The only reagents added are soda ash as an inorganic carbon source to
aid nitrification, and phosphorus as a trace nutrient. Total cyanide
is reduced to 0.30 mg/1 from an influent concentration of 2.0 mg/1;
thiocyanate content is reduced to less than 0.10 mg/1 from 50.0 mg/1.
Metals are returned to the tailings pond.
Environmental Fate of Cyanide in Heap Leach Mining Wastes
The chemical and biological processes controlling the fate of
cyanide in heap leach mining operations are summarized in Figure 20
(Chapter 4). These processes were discussed in detail in the section
entitled, Environmental Fate of Cyanide. Heap leach mining wastes may
contain free cyanide (HCN and CN ), metal cyanide complexes, and salts
of metal cyanide complexes. The process controlling the fate of free
cyanide in these wastes is volatilization of HCN to the atmosphere.
HCN will diffuse upward through the troposphere and is destroyed in the
stratosphere (Singh et al., 1984). An important control on volatiliza-
tion is pH; below a pH of 9, HCN is predominant over cyanide ion.
Metal cyanide complexes such as iron, copper, zinc, nickel,
cobalt, and cadmium, which are the most common at gold and silver
operations (Huiatt, 1985), decompose and release cyanide ion at varying
rates. Zinc and cadmium complexes, the least stable complexes, readily
decompose as free cyanide decreases during the rinsing process. Strong
complexes such as iron cyanide complex may remain in the ore. Iron
cyanide complexes have been found to degrade in solutions exposed to
ultraviolet light, but the photochemical effect on the solid species is
unknown. As the concentration of free cyanide decreases below the
concentration of metal cyanide complexes, the slower rate of decomposi-
tion of metal cyanide complexes becomes the rate controlling step for
the volatilization of free cyanide. Other compounds that may be very
sparingly soluble in water are iron, nickel, cobalt, and copper salts
of iron complex cyanide ions. Until the presence of these complexes
and compounds is exhausted, very small amounts of free cyanide may be
released in the spent heap pile.
332
-------
Besides volatilization directly from the mining wastes, a secon-
dary transport process is the leaching of cyanide and any soluble metal
cyanide complexes from the mining wastes and their transport into the
environment if uncontained. Also possible would be the accidental
release of cyanide process solution through pond overflows and pad or
pond leaks (refer to Appendix D for reported accidents at heap leach
mining operations). Volatilization is an important process for remov-
ing cyanide from surface water whereas other processes (biodegradation,
reaction of cyanide to ammonia and formate, sorption, complexation, and
others) may be more important for soil and ground water. The discus-
sion of the mobility of cyanide in surface water, ground water, and
soils is contained in the final part of the section, Environmental Fate
of Cyanide.
333
-------
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340
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APPENDIX G
POTENTIAL EFFECTS OF CYANIDE
Cyanide in various forms can adversely affect living organisms.
Free cyanide (CN-) and hydrogen cyanide (HCN) are readily absorbed and
combine with certain enzymes in living tissue. Cyanide predominately
affects respiration by inhibiting cytochrome oxidase, an enzyme re-
quired for oxidative metabolism.
Hydrogen cyanide is lethal to fish at water concentrations of 25
ug/1, but effects on reproduction have been observed at levels as low
as 5.2 ug/1. Water temperature and the presence of light affect the
toxicity of cyanide to aquatic organisms.
Loss of vegetation can result from cyanide spills, while sub-
lethal concentrations can affect photosynthesis. Plant growth can be
inhibited by cyanide in the presence of iron, but seed germanation can
be increased by sodium cyanide. Concentrations of HCN greater than 5
mg/1 in irrigation water have been found to adversely affect some
vegetation.
Cyanide can enter the bloodstream of birds and mammals (including
humans) after inhalation, ingestion or cutaneous absorption. Toxici-
ties of ingested hydrogen cyanide are reported at 3 mg/kg body weight
for mice, at 0.1 mg/kg body weight for birds, and at about 1 to 3 mg/kg
body weight for humans. Inhalation of 100 to 300 mg/1 HCN is fatal to
most mammals, including humans. The human lethal dose for skin absorp-
tion is about 100 mg/kg body weight. Sublethal doses are detoxified
and eliminated from the body. However, the detoxification process may
inhibit iodine uptake, causing goiters.
Toxicity of cyanide to various organisms is discussed in greater
detail below. For a discussion on the behavior of cyanide in the
environment, see Appendix B.
341
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TOXICITY OF CYANIDE TO AQUATIC ORGANISMS
Introduction
Cyanide can be introduced into aquatic organisms by absorption
through the skin or the gills and is readily transported throughout the
body by general circulation. Of the many forms of cyanide, free
cyanide is the most toxic to aquatic organisms. Between pH 6.8 and 8.3
the molecular species, hydrogen cyanide (HCN), is more toxic than the
ionized species, cyanide ion (CN ). Molecular hydrogen cyanide
diffuses through semi-permeable membranes more readily than the cyanide
ion, but once inside, the ionic form becomes the reactive agent because
of its unpaired electron (Huiatt et al., 1983; Heraing and Thurston,
1984). Above pH 8.3, CN also readily penetrates these membranes. The
unpaired electron produces a strong nucleophilic center and therefore
reacts with many transition metals and sulfhydryl groups.
Metalloporphyrins and molecules with a disulfide bond are the most
important biological molecules affected by HCN. Metalloporphyrins
which are sensitive to cyanide inhibition include cytochrome oxidase,
catalases, and peroxidases. Cyanide inhibits oxidative phosphorylation
causing cytotoxic anoxia. Death results from depression of the central
nervous system which is the most sensitive tissue to anoxia. The
effect of cyanide to catalase and cytochrorae oxidase is reversible.
Cyanide irreversibly affects sulfur-containing enzymes involved in
respiration (Huiatt et al. , 1983). Succinate dehydrogenase is an
iron-sulfur protein which passes electrons to the cytrochrome system
and is inhibited by cyanide.
Cyanide is detoxified primarily by the enzyme rhodanese which
forms the less toxic thiocyanate ion. However, thiocyanate interferes
with the incorporation of iodide by the thyroid gland. A continuous
intake of HCN without sufficient iodine in the diet to overcome its
effect causes goiter. Thiocyanate also inhibits transport of halides
in the stomach, cornea, and gills, and inhibits other enzymes (Heming
and Thurston, 1984).
342
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The toxicity of metallocyanide complexes depends on the degree to
which they dissociate to release free cyanide. Zinc cyanide and
cadmium cyanide complexes readily dissociate in aqueous solutions and
are highly toxic. Copper cyanide, nickel cyanide, and silver cyanide
dissociate to a moderate degree while iron cyanide and cobalt cyanide
are tightly bound and considered nontoxic (Heming and Thurston, 1984).
However, ferrocyanide and ferricyanide, which may be byproducts of the
cyanidation process used to extract gold from ore, may photodecompose
and become much more toxic (Burdick and Lipshuetz, 1950; Heming and
Thurston, 1984).
Free cyanide is a much more reliable index of toxicity than total
cyanide because total cyanide can include organic cyanides and metal-
locyanide complexes (U.S. Environmental Protection Agency, 1985).
Measurement of free cyanide should be adequate for monitoring purposes
if performed often over a wide area. However, if only a few measure-
ments are made on a water body or if an effluent is measured, free
cyanide at the lowest pH occurring in the receiving water, cyanide
amendable to chlorination, or total cyanide may be more appropriate
(U.S. Environmental Protection Agency, 1985) (see Appendix B for a more
complete discussion). If total cyanide is much higher than free
cyanide or cyanide amenable to chlorination, the importance of free
cyanide released from metallocyanide complexes should be considered.
Also, dilution of an effluent with receiving water before measuring
cyanide should demonstrate whether the receiving water can decrease the
cyanide of concern because of sorption or complexation.
Acute Toxicity of Cyanide
Concentrations of hydrogen cyanide lethal to fish range from about
25 ug/1 to about 300 ug/1 whereas invertebrates are typically much more
tolerant (Table C-l). Salmonids, especially rainbow trout (Salmo
gairdneri) are the most sensitive fish species. Embryos and sac fry
tend to be more tolerant than juveniles and adults.
343
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Table C-l
Toxlclty of Cyanide (HCN) to Aquatic Animals
Species
Salvellnus fontlnalls (juvenile)
(juvenile)
(juvenile)
(swim-up fry)
Plmephalea promelas (juvenile)
Lepomls macrochlrus
Perca flavescens
Salmo galrdnerl (juvenile)
Salmo salar
Plmephales promelas
Lepomls macrochlrus
Salvellnus fontlnulls
Carasslus aura t us
Asellus communls
Garamarus pseudollmnlus
Pteonarcys dorsata
Tanytarsus dlsslmllls
Plmephales promelas
Concentrations
a/ wlth
96-h LC50 MATC ' Effects
(ug/1) (ug/1) (ug/1)
75; 6.9 °C
88; 10 °C
98; 13 °C
55-104
121; 15 °C
137; 20 °C
129; 25 "C
83; 8.4 "C
87; 15.0 °C
120; 24.9 °C
90; 15 °C
102; 21 °C
28; 6 °C
42; 12 °C
68; 10 °C
73; D.0.b/
10 mg/1 (24 hr)
24; D.O. - 3.5
mg/1 (24 hr)
114 (192 hr)
116 (168 hr)
126 (288 hr)
261 (336 hr)
2295 41, c/ 55d/
169 16C/, 21d/
4,e/ 9f/
426
2490
19.6
Remarks Authors
Smith et al. , 1978
Kovaca and Leduc, 1982
Alabaster et al., 1983
Cardwell et al., 1976
Reduced numbers and weight. Gamma rus was affected Oseld and Smith, 1979
by presence of Asellus.
U.S. EPA, 1985
U.S. EPA, 1985
Egg production reduced. Llnd et al., 1977
(continued)
-------
Table C-l (Continued)
96-h LC50
(ug/1)
Lepomls macrochlrus
Jordanella floridae
U)
J>
Ui
Salmo gairdnerl
Salmo gairdnerl
Salmo gairdnerl, juv.
Salmo gairdnerl
Salmo salar
HATC
a/
Concentrations
with
Effects
(ug/1)
5 (to pro- 65.6
tect com- 80.0
plate life 5.0
history)
50 (without 50.2
reproduction 15.6-19.A
or fry life 54.0
stages); 25°C
75.0
65.0 (5 days)
65.0
75-87.0
65.0
10.0
Remarks
Authors
5.0
60% survival
40% survival
Spawning Inhibited
Behavioral changes after 289 days
Fry survival affected
Juvenile survival affected
Reduced hatching success to 37%; egg production
of exposed embryos reduced by 33%.
Embryonic, juvenile exposure caused 40% reduction
In egg production; 33% reduction In hatching of Fl
30% of treated embryos had eye defects.
40% of treated embryos had eye defects.
Delayed sexual maturity and shortened estrous
cycle.
Increased food maintenance requirements by 2-3
times of 18-g, but not 8-g fish. Growth rate of
18-g fish reduced 98%; of 8-g fish by 60%.
Klmball et al., 1978
Cheng and Ruby, 1981
10.0 (18 days) Reduced spermatogonla by 13%.
30.0 (18 days) Reduced spermatogonla by 50%.
20.0 (18 days) 40% growth reduction.
30.0 (18 days) 95% growth reduction and degenerative
necrosis of hepatocytes.
10.0 (20 days, Altered patterns of secondary yolk deposition.
10°C during
late egg
development)
20.0 (20 days, Secondary yolk deposition delayed.
10°C during
early summer)
60% of oocytes failed to reach secondary yolk
deposition.
McCracken and Leduc, 1978
Ruby et al., 1979
Dlxon and Leduc, 1981.
Lesnlak and Ruby, 1982.
10.0 (20 days
In mid-
summer)
80-100, Delayed hatching by 6-9 days. Reduced
continuously hatching success.
10.0 Conversion of yolk Into body tissue reduced.
Leduc, 1978.
(continued)
-------
Table C-l (Continued)
Salvellnus
a/
b/
c/
d/
e/
f/
MATC •
D.O. =
Based
Based
Based
Based
Species
fontlnalls
96-h LC50
(ug/1)
Concentrations
a/ Mlth
MATC Effects Remarks Authors
(uT/T) (ug/1)
5.7-11.2 34.0 Growth was affected. Koenst et al., 1977.
11.2 Egg production was reduced.
53.9 Egg viability was reduced.
64.9 No viable eggs were produced.
• Maximum acceptable toxicant concentration.
• Dissolved oxygen.
on total number of
on number of eggs
on total number of
on number of eggs
eggs or young In
per gravid female
eggs or young In
per gravid female
brood pouch.
.
brood pouch and competition with Asellus.
and competition with Asellus.
-------
Temperature is an important factor in the toxicity of hydrogen
cyanide. Toxicity of HCN to fish generally increases with decreasing
temperature (Smith et al. , 1979; Kovacs and Leduc, 1982) (Table C-l).
At slowly-lethal concentrations (greater than 100 ug/1 HCN), HCN was
more toxic at lower temperatures, but at rapidly-lethal concentrations,
HCN was more toxic at higher temperatures. Kovacs and Leduc (1982)
also found that warm-acclimated trout survived longer in lethal con-
centrations of HCN.
Lethal threshold concentrations were reduced 20 to 30 percent when
oxygen concentration was reduced by 50 percent (Smith et al. , 1979).
Brook trout (Salvelinus fontinalis) alevins with yolk sacs exhibited a
500 percent decrease in lethal threshold concentrations, while alevins
which had absorbed their yolk sacs became 200 percent more sensitive.
Alabaster et al. (1983) reported a decrease of 67 percent in the LC50
(lethal concentration to 50 percent of the organisms) when dissolved
oxygen declined from 10 rag/1 to 3.5 mg/1.
There is little information which addresses the affect of hardness
on the toxicity of HCN. In general, hardness of water appears to have
no significant affect on the toxicity of hydrogen cyanide (Huiatt et
al., 1983).
Because the iron cyanide complexes photodecompose, light has an
effect on toxicity of these cyanide complexes. Burdick and Lipschuetz
(1950) found that potassium ferrocyanide or ferricyanide in concen-
trations of 2000 ug/1 rapidly became toxic in the presence of light.
Increasing the intensity of light also increased the toxicity of
ferrocyanide and ferricyanide (Heraing and Thurston, 1984). However,
unless receiving waters are clear and shallow, photolysis of the
iron-cyanide complexes is probably not nearly as rapid as that observed
in laboratory tests. Free cyanide produced by photolysis may react and
complex again or escape to the atmosphere as quickly as it is released.
Lethal concentrations of cyanide may not be often attained even in
waters receiving large amounts of iron-cyanide complexes (Doudoroff,
1976).
347
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Pre-exposure to high sublethal levels (50 ug/1) of hydrogen
cyanide can cause a reduced tolerance to lethal concentrations of
hydrogen cyanide. Dixon and Sprague (1981) exposed rainbow trout to
0.35 of the incipient lethal level of cyanide for 1 and 2 weeks.
Tolerance to cyanide decreased by 32 and 15 percent, respectively.
Following this initial sensitization, tolerance returned to that of
control fish after 21 days. Pre-exposure to low sublethal levels (10
ug/1) can increase resistance to a lethal concentration (Douderoff,
1976).
The effect of cyanide appears to be related to the metabolism and
therefore the size of fish. Anderson and Weber (1975) found the LC50
of HCN for guppies (Poecilla reticulata) depended on weight and was
0 72
described by 0.147W * , where W is the weight in grams of a group of
10 fish of a given size class. Less toxicant was required to kill one
gram of heavy fish than one gram of light fish (Anderson and Weber,
1975). McCracken and Leduc (1978) also reported HCN affected large
rainbow trout more strongly than small trout. Since cyanide is a
respiratory depressant, an increase in size causes an unproportional
cost of ventilation because large fish have a proportionally smaller
gill area. The authors proposed that cyanide could act as a regulator
of the basal metabolic rate.
Chronic Toxicity of Cyanide
Reproduction
Cyanide affects spawning, egg production, egg development, and
production of spermatogonia (Table C-l). Spawning of bluegill sunfish
(Leponis macrochirus) was inhibited at 5.2 ug/1 HCN (Kimball et al.,
1978). Egg production per female brook trout was reduced by 50 percent
following a 144-day exposure to 27 ug/1 HCN at 9 to 15° C (48 to 59° F)
(Koenst et al., 1977). Egg production per female fathead minnow
(Pimephales promelas) was reduced by 50 percent at an HCN concentration
of approximately 15 ug/1. Cheng and Ruby (1981) followed the effects
of cyanide through the Fl (second) generation of American flagfish
(Jordanella floridae), and found juvenile ovaries were highly sensitive
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to HCN. A 5-day exposure of embryos and juveniles to 65 ug/1 HCN
produced a 40 percent reduction in egg production at sexual maturity
and a further 33 percent reduction in the hatching success of the Fl
generation. Embryonic exposure alone to 75 ug/1 HCN reduced by 30
percent the fecundity of the embryos which matured. Exposure during
embryonic development also appeared responsible for a shortened estrous
cycle and delayed sexual maturity.
The development of oocytes and spermatogonia of rainbow trout is
seriously affected by cyanide (Table C-l). Lesniak and Ruby (1982)
found that yolk deposition was delayed or failed following exposure to
HCN at 10 to 20 ug/1 for periods of 15 to 20 days during early, mid,
and late development periods. Following exposure to 10 and 30 ug/1
HCN, 13 and 50 percent, respectively, of dividing spermatogonia in
juvenile trout failed to complete mitosis (Ruby et al., 1979).
Early Life Stages
As described in the previous section, hatching success can be
adversely affected by exposure to cyanide of the developing oocytes
before they are fertilized. Although Smith et al. (1979) described the
egg as the most tolerant stage, hatching success of Atlantic salmon
(Salmo salar) eggs was reduced by 15 to 40 percent when incubated in
HCN concentrations of 80 to 100 ug/1 (Leduc, 1978). During incubation,
conversion of yolk into body tissues was reduced at concentrations
above 10 ug/1 HCN. The authors stated that sensitivity of the egg
begins when morphogenesis becomes aerobic after blastulation. Observed
teratogenic anomalies seemed to arise from this sensitivity of aerobic
processes during embryogenesis. Survival of sac fry and larvae was not
adversely affected by HCN. At intermediate concentrations, fry grew
faster than controls because yolk conversion efficiency ratios were
higher, especially at 40 ug/1 HCN or more.
Kimball et al. (1978) also reported a significant reduction in
survival of blue gill sunfish eggs at 38.6 ug/1 HCN. Fry survival was
also adversely affected at 15.6 to 19.4 ug/1 HCN, but juveniles were
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not affected by concentrations below 53.1 ug/1 at 25° G (77° F). Eye
defects were observed in 30 percent of American flagfish embryos
exposed to 65 ug/1 HCN and in 40 percent of embryos exposed to 75 ug/1
HCN (Cheng and Ruby, 1981).
Juvenile and Adult Life Stages
As discussed previously, the juvenile ovary is highly sensitive to
cyanide. The growth response of juvenile fish to HCN is variable.
Dixon and Leduc (1981) observed that growth was reduced by 40 to 95
percent following 18 days of exposure to 20 and 30 ug/1 HCN, respec-
tively. This severe initial repression of the specific growth rate was
followed by a highly significant growth increase which was insufficient
to compensate for the initial repression. Wide-spread degenerative
necrosis of the hepatocytes was discovered at 10 ug/1 HCN although no
other poisoning symptoms appeared. Growth enhancements may also occur
at low concentrations (about 10 ug/1 HCN) when the metabolic rate of
fish is stimulated (McCracken and Leduc, 1978; Kovacs and Leduc, 1982).
McCracken and Leduc (1978) described cyanide-induced lipogenesis in
small rainbow trout (8 grams) but a depletion in fat reserves in large
trout (18 grams). Cyanide increased food maintenance requirements of
18-gram rainbow trout by 2 to 3 times over controls, but it had no
effects on 8-gram trout at 10 ug/1. Cyanide caused growth to be
proportional to body surface rather than weight so large fish were
severely affected while growth in small fish was enhanced.
The survival of bluegill sunfish was not markedly affected by
cyanide at sublethal concentrations until spawning started. Death
occurred after a series of behavioral changes which included a lack of
feeding activity and aggressiveness; impairment of the ability to judge
distance and capture prey; and gradual changes in swimming behavior.
The time from the first observation of these symptoms to death was two
weeks. Early stages were noticeable at 50.2 ug/1 HCN after 289 days.
Survival was 60 percent at 65.6 ug/1 HCN and 40 percent at 80.0 ug/1.
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Invertebrates
When the aggressive and competitive araphipod Gammarus pseudolim-
nius was exposed to hydrogen cyanide, the competitive advantage shifted
to the isopod Asellus communis which is more tolerant of cyanide (Oseid
and Smith, 1979) (Table C-l). Asellus was able to reproduce at HCN
concentrations up to 317 ug/1 after a continuous exposure of 115 days.
Gammarus required much lower cyanide concentrations to reproduce.
Cyanide Concentrations Which Protect Aquatic Life
Koenst et al. (1977), Leduc (1978), and Kimball et al. (1978)
determined that the maximum acceptable tolerance concentration, or
no-effect concentration, is 5 to 10 ug/1 HCN for fish, which is similar
to that determined for Gammarus pseudolimnius (Table C-l). Other
invertebrates can tolerate much higher concentrations. If reproduction
and early life stages of bluegill sunfish are not considered, 50 ug/1
HCN can be tolerated at higher temperatures (25° C or 77° F).
The EPA determined that freshwater organisms and their uses should
not be unacceptably affected if free cyanide does not exceed 5.2 ug/1
more than once every three years on the average and if the 1 hour
average does not exceed 22 ug/1 more than once every three years on the
average. These criteria may be overly protective when measuring
cyanide as total cyanide.
EFFECTS OF CYANIDE ON VEGETATION, LIVESTOCK AND WILDLIFE
Introduction
Cyanide is a highly reactive molecule. In the environment free
cyanide will react with various forms of sulfur to form thiocyanate,
complex with trace metals, be metabolized by microorganisms, oxidize to
cyanate and degrade chemically to carbon dioxide and ammonia, react
with organic matter and/or react to ammonia and formate (Huiatt, et al.
1983). The soil factors most responsible for attenuation of cyanide in
the environment are clay content, depth of soil, hydrous oxides of
various metals, aerobic conditions and concentration of soil organic
matter (Fuller, 1985).
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No evidence of bioaccumulation of coraplexed cyanides within
organisms or food chains is reported in the technical literature.
Studies have shown that cyanide is readily metabolized and/or converted
to non- or less toxic forms by several species of microorganisms,
plants, and animals.
Cyanide compounds occur naturally in the majority of plant species
studied. The main group of cyanide compounds in plants is the cyano-
genic glycosides. These compounds have been identified in approxi-
mately 1,000 plant species (Towill et al., 1978). Plants such as
sorghum and arrow-grass (Triglochin spp.) can develop concentrations of
cyanogenic glycosides which release enough cyanide to poison cattle and
sheep (Towill et al., 1978). When livestock consume such plants,
cyanogenic glycosides are hydrolyzed, releasing hydrogen cyanide.
Effects on Vegetation
Plants are able to metabolize sublethal concentrations of exter-
nally-added hydrogen cyanide. Toxic concentrations of cyanide to
plants can occur in the event of a cyanide release if the soil micro-
bial degradation rate and natural soil attentuating capacities of the
soil are exceeded (Fuller, 1985). Toxic spills of cyanide may result
in the loss of vegetation in the immediate vicinity (Stanton et al. ,
1985).
There is little published information on concentrations of cyanide
in soils which may be toxic to plants. Dandelion in a 5,000 mg/1
solution of sodium cyanide developed numerous dead leaves after 48
hours (Howe and Noble, 1983). Alfalfa responses to cyanide in
irrigation water was found to be depressed at greater than 5 mg/1 of
hydrogen cyanide (Overcash and Pal, 1979).
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The toxic effect of cyanide in plants in due primarily to inhibi-
tion of various enzymes (Towill et al., 1978). Cytochrome oxidase, the
terminal electron acceptor in the electron transport chain, is probably
the most sensitive enzyme. Plant respiration is affected by inhibition
of cytochrorae oxidase. Cyanide can react with metals in other enzymes
such as uricase, nitrate reductase, tyrosinase, and carboxypeptidase,
thus rendering these enzymes ineffective.
Cyanide can adversely affect photosynthesis by removal of copper
from plastocyanin (Towill et al., 1978). Evidence suggests that plant
growth can be inhibited by cyanide, especially in the presence of iron.
Conversely, seed germination can be stimulated by soaking in a solution
of sodium cyanide (Towill et al., 1978).
Effects on Livestock and Wildlife
Considerable research has been conducted on the effects of cyanide
on aquatic organisms (refer to the previous section on toxicity of
cyanide to aquatic organisms). Information about the effects of
cyanide on terrestrial wildlife is not as complete (Stanton et al.,
1985).
Free cyanide and its alkali metal salts have a high inherent
lethality to man and other mammals (Huiatt et al. , 1983). Lethal
threshold concentrations vary among species tested. The concentration
reported to be toxic to mice is 3 mg/kg while that for birds is about
0.1 mg/kg. Airborne HCN levels greater than 200 ppm are regarded as
lethal to mammals while levels of 80 to 160 ppm may cause sublethal
toxic effects (Feigley et al., 1985). As in plants, the main
inhibitory effect of cyanide in mammals is on respiration.
Research with dogs indicates that large (0.5 to 2.0 mg/kg) but
sublethal doses of cyanide administered periodically may be tolerated.
Rats fed diets containing as much as 300 ppm cyanide for up to three
years showed little chronic effects (Feigley et al. , 1985). Other
researchers observed neither death nor clinical signs of toxicity in
rats fed diets containing 1,500 ppra potassium cyanide or 2,240 ppm
potassium thiocyanate for nearly 1 year (Feigley et al., 1985). There
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is currently no evidence that chronic exposure to cyanide results in
teratogenic (changes produced in offspring), rautagenic or carcinogenic
effects. However, extensive evidence exists to support the contention
that long-term adverse effects can occur to humans and other animals
which consume cyanide-containing food and medicine (Stanton et al.,
1985).
An operating heap leach operation may contain a solution concen-
tration of about 500 mg/1 of sodium cyanide (equivalent to about 250
mg/1 free cyanide) (Stanton et al., 1985). A properly operating
facility where access is controlled, should pose little threat to
livestock and wildlife. Releases of cyanide would be more likely to
affect aquatic life although some poisoning of animals drinking process
solution could occur. Cyanide emissions from heap leaching would have
to be greater than 80 mg/1 to potentially affect rodent populations
(Feigley et al., 1985).
In documented cases of acute cyanide poisioning, the affected
animal becomes severely distressed and either dies or rapidly recovers.
Due to cyanide's high biological reactivity and plant and mammalian
detoxification mechanisms, cyanide is not accumulated or stored in any
mammalian species studied (Huiatt et al., 1983).
HUMAN HEALTH EFFECTS OF CYANIDE
The toxicological effects of cyanides on humans are based on their
potential for rapid conversion to hydrogen cyanide (HCN). Cyanide can
be absorbed into the bloodstream after inhalation, ingestion, or
cutaneous adsorption. In the bloodstream, cyanide binds to metal con-
stituents of certain enzymes, the most sensitive of which is cytochrome
oxidase. The cyanide ion reacts with the trivalent iron present in the
cytochrome oxidase, inactivating the enzyme, thereby preventing oxygen
utilization by the cells. The central nervous system is particularly
dependent on oxidative metabolism, the absence of which causes cyto-
toxic anoxia, with death resulting from depression of the central
nervous system. In sublethal doses, cyanide is converted by cells to
less toxic forms. The primary detoxification pathway is the reaction
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of cyanide with thiosulfate in the presence of the enzyme rhodanese, to
produce thiocyanate. Thiocyanate is eliminated in the urine. There is
a low degree of chronic toxicity because cyanide is either lethal or
detoxified. It does not bioaccumulate in the body, and there is no
evidence that cyanide is mutagenic, teratogenic, or carcinogenic.
However, Hamilton and Hardy (1974) have implicated a degradation
product of cyanide, i.e. thiocyanate, in the development of goiters in
animals. They suggest the thiocyanate radical, by preventing iodine
uptake, may be responsible for the effect. It has been suggested that
continued exposure to cyanide in industry, even at low levels, can
produce thiocyanate changes in the thyroid gland.
Hydrogen cyanide vapor is rapidly absorbed through the lungs.
Inhilation of 100 to 300 mg/1 HCN vapor is fatal (Huiatt et al., 1983).
Tobacco smoke is a common source of low concentration HGN, which is
converted to thiocyanate by the body and excreted. Inhalation of
cyanide salt dusts can also be absorbed into the bloodstream since the
cyanide will dissolve on contact with moist mucous membranes of the
lungs.
The mean lethal dose of cyanide substances Ingested by mouth in
human adults is in the range of 50 to 200 milligrams (Huiatt et al. ,
1983). The EPA (1985) recommends an ambient water quality concentra-
tion not to exceed 0.2 mg/1 free cyanide which would be protective of
human health against ingestion of contaminated water and fish found in
contaminated water. No human cases of illness or death from cyanide in
water supplies are known although some waste cyanide is still being
discharged from such industries as steel and electroplating, mining
operations, and hospital laboratories.
Hydrogen cyanide can also be absorbed through the skin particular-
ly if the skin is cut, abraded, or moist. There is one reported case
(Potter, 1950) in which liquid HCN ran over the bare hand of a worker
wearing a respirator. The worker collapsed into deep unconsciousness
within five minutes. The lethal dose (LD50) for skin absorption is
about 100 mg/kg body weight (Huiatt et al., 1983).
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Alabaster, J. S., D. G. Shurben, and M. J. Mallett. 1983. The acute
lethal toxicity of mixtures of cyanide and ammonia to smolts of
salmon, Salmo salar L. at low concentrations of dissolved oxygen.
Fish Biol. 22: 215-222.
Anderson, P.D., and L. J. Weber. 1975. Toxic response as a
quantitative function of body size. Toxicol. Appl. Pharmacol.
33:471-483.
Burdick, G. E. and M. Lipschuetz. 1950. Toxicity of ferro and ferri
cyanide solutions to fish, and determination of the cause of
mortality. Trans. Amer. Fish. Soc. 78: 192-202.
Cardwell, R. D. , D. G. Foreman, T. R. Payne, and D. J. Wilbur. 1976.
Acute toxicity of selected toxicants to six species of fish.
EPA-600/3-76-008. U.S. Environmental Protection Agency, Environ-
mental Research Laboratory, Duluth, MN 125 pp.
Cheng, S. K., and S. M. Ruby. 1981. Effects of pulse exposure to
sublethal levels of hydrogen cyanide on reproduction of American
flagfish. Arch. Environra. Contain. Toxicol. 10: 105-116.
Dixon, D. G., and Q. Leduc. 1981. Chronic cyanide poisoning of
rainbow trout and its effects on growth, respiration, and liver
histopathology. Arch. Environm. Contam. Toxicol. 10:117-131.
Dixon, D. G., and J. B. Sprague. 1981. Acclimation induced changes in
toxicity of arsenic and cyanide to rainbow trout, Salmo gairdneri
Richardson. J. Fish Biol. 18: 579-589.
Doudoroff, P. 1976. Toxicity to Fish of Cyanide and Related Com-
pounds, A Review. EPA-600/3-76-038. U.S. Environmental Protec-
tion Agency, Washington, D.C.
Feigley, H. P., J. F. Heisinger, and R. J. Douglass. 1985. The use of
rodents in identifying and monitoring potential environmental
impacts from cyanide at a heap leaching facility in South Dakota.
_In_ Van Zyl, E. (ed.). Cyanide and the Environment. Department of
Civil Engineering, Colorado State University. Fort Collins,
Colorado.
Fuller, W. H. 1985. Cyanides in the environment with particular
attention to the soil. _In Van Zyl, D. (ed.). Cyanide and the
Environment. Department of Civil Engineering, Colorado State
University. Fort Collins, Colorado.
Hamilton D. and H. L. Hardy. 1974. Industrial Toxicology. Publishing
Science Group, Inc., Acton, Miss.
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Heraing, T. A., and R. V. Thurston. 1984. Physiological and toxic
effects of cyanide to fishes: A review and recent advances. Pages
85-104. _In Van Zyl, D. (eds.). Cyanide and the Environment.
Department of Civil engineering, Colorado State University, Fort
Collins, Colorado.
Howe, M. and D. Noble. 1983. Effect of cyanide residue on vegetation
bordering a Black Hills stream. Salt Lake city, Utah. SME-AIME
meetings October 19-21, 1983.
Huiatt, J. L., J. E. Kerrigan, F. A. Olson, and G. L. Potter (eds.)
1983. Proceedings of a Workshop: Cyanide from Mineral Processing
1982. Utah Mining and Mineral Resources Research Institute, Salt
Lake City, Utah.
Kiraball, G. L., L. L. Smith, Jr., and S. J. Broderius. '1978. Chronic
toxicity of hydrogen cyanide to the bluegill. Trans. Am. Fish.
Soc. 107(2):341-345.
Koenst, W. M., L. L. Smith, Jr., and S. J. Broderius. 1977. Effect of
chronic exposure of brook trout to sublethal concentration of
hydrogen cyanide. Enviorn. Sci. Technol. 11: 883-887.
Kovacs, T. G., and G. Leduc. 1982. Acute toxicity of cyanide to
rainbow trout (Salmo gairdneri) acclimated at different tempera-
tures. Can. J. Fish Aquat. Sci. 39: 1426-1429.
Leduc, G. 1978. Deleterious effects of cyanide on early life stages
of Atlantic salmon (Salmo salar). J. Fish. Res. Board Can. 35:
166-174.
Lesniak, J. A., and S. M. Ruby. 1982. Histological and quantitative
effects of sublethal exposure or oocyte development in rainbow
trout. Arch. Environm. Contam. Toxicol. 11: 343-352.
Lind, D. T. , L. L. Smith, Jr., and S. J. Broderius. 1977. Chronic
effects of hydrogen cyanide on the fathead minnow. S. Water
Pollut. Control Fed. 49: 262-268.
McCracken, I.R., and G. Leduc. 1978. Allometric growth response of
exercised rainbow trout to cyanide poisoning. Pages 303-320. In
J. G. Eaton, P. R. Parish, and A. C. Hendricks (eds.). Aquatic
Toxicology. ASTM STP 707. American Society for Testing and
Materials, Philadelphia. 405 pp.
Oseid, D. M. , and L. L. Smith, Jr. 1979. The effects of hydrogen
cyanide on Asellus communis and Gammarus psudalimnaeus and changes
in their competitive response when exposed simultaneously. Bull.
Environ. Contam. Toxicol. 21: 439-447.
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Overcash, M. R. and D. Pal. 1979. Design of Land Treatment Systems
for Industrial Wastes - Theory and Practice. Ann Arbor Science.
Ann Arbor, Michigan.
Potter, A. L. 1950. The successful treatment of two recent cases of
cyanide poisoning. Br. J. Ind. Med. (Great Britain) 7:125-130.
Ruby, S. M., D. G. Dixon, and G. Leduc. 1979. Inhibition of sperma-
togenesis in rainbow trout during chronic cyanide poisoning.
Arch. Environm. Contam. Toxicol. 8: 533-54A.
Smith, L. L., Jr., S. S. Broderius, D. M. Oseid, G. L. Kimball, and W.
M. Koenst. 1979. Acute toxicity of hydrogen cyanide to fresh-
water fishes. Arch. Environ. Contam. Toxicol. 7: 325-337.
Stanton, M. D., T. A. Colbert, and R. B. Trenholme. 1985. Environ-
mental Handbook for Cyanide Leaching Projects. Washington, D.C.
National Park Service.
Towill, L. E., J. S. Drury, B. L. Whitfield, E. B. Lewis, E. L. Galyan,
and A. S. Mammons. 1978. Reviews of the Environmental Effects of
Pollutants: V. Cyanide. Cincinnati, Ohio. Office of Research
and Development. U.S. Environmental Protection Agency -
U.S. Environmental Protection Agency. 1985. Ambient Water Quality
Criteria for Cyanide - 1984. U.S. Environmental Protection
Agency, Washington, D.C. EPA 440/5-84-028.
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APPENDIX D
CYANIDE SPILLS AND RESULTING
ENVIRONMENTAL ATTENUATION FACTORS
ACCIDENTS FROM HEAP LEACHING PRACTICES IN THE WESTERN UNITED STATES
AND THEIR IMPACTS
The accidental spill record for heap leach operations in the
western United States indicates that several accidents having detri-
mental impacts have occurred. By far the most common type of problem
has been with ponds overflowing during periods of high runoff. The
other types of accidents are usually related to either leaks in the
pond liners or leaks in the heap pad liners. The incidents which have
been reported to each state and their impacts, when they could be
identified, are described below.
Arizona
There are several cyanide heap leach operations in Arizona. Under
Arizona state law, state officials are not permitted to divulge infor-
mation regarding accidents or spills which occur in the mining industry
(J. McCutchan, Arizona State Mine Inspector, personal communication,
1986).
California
Mining operations in California are regulated by separate regional
water quality divisions. Three regions have active cyanide heap leach
activities. In Region 5, an accident occurred in the spring of 1986 at
the Cal-Gon mine near Canyon Dam (B. Kroyle, California Regional Water
Quality Board-Region 5, personal communication, 1986). Waters from the
process ponds had to be released after a large snowstorm, combined with
warm weather and rain storms, caused ponds to overflow. The site is
located on 25 meters (80 feet) of impermeable clay so the operators
were able to dig temporary ponds for storage of some of the excess
water. However, 23,000 cubic meters (6 million gallons) of treated
waters (5 to 20 mg/1 free cyanide) had to be released at a rate of
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0.0022 cubic meters per second (35 gallons per minute). The outflow
point was located 6 meters (20 feet) from a tributary stream that was
flowing at a rate of approximately 0.022 cubic meters per second (350
gallons per minute). Concentrations of free cyanide ranged from 20 to
30 mg/1 in this tributary. The creek then flowed approximately 2.4
kilometers (1.5 miles) to Wolf Creek, which was flowing at approxi-
mately 60 cubic meters per second (2000 cfs). No cyanide was detected
in Wolf Creek (detection limit 0.01 mg/1). The higher concentrations
of cyanide in the tributary are believed to be a result of mismanaged
tailings from past operations. Five ground water monitoring wells were
installed. Samples from one well contained small amounts of cyanide.
Chlorine was immediately added to the well to oxidize the cyanide. An
extensive program of aquatic life sampling was conducted but no aquatic
life problems were found.
In Region 6 there has been a slight problem with one of the
heap leach double-synthetic pad liners constructed by Beaver Resouces
(M. Watkins, California Regional Water Quality Board - Region 6,
personal communication, 1986). The liner was installed properly but
heavy machinery was permitted to drive across the liner which tore and
weakened it. The leak was localized and the leachate was contained in
the leak detection system. There was no known contamination in either
the ground water or surface water.
Leakage has also been reported from an inactive heap leach opera-
tion of the American Mine in the Mojave Desert also located in Region 6
(U.S. Environmental Protection Agency, 1986). Breaks in the PVC liners
used below several inactive leach heaps allowed rainwater to percolate
through the heaps and into the soil at 59 sample locations. Soil core
samples were analyzed for free cyanide and it was found that the
maximum penetration into the soil ranged from 46 to 61 centimeters (18
to 24 inches). Four heaps were analyzed. Two of the heaps, which had
been idle for more than 2 years, contained no measurable cyanide while
some samples from the other two heaps had free cyanide concentrations
from 10 to 150 mg/1. Water and sediment samples were also collected in
the barren and pregnant solution ponds below the inactive heaps and
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from the soils adjacent to and below the ponds. Free cyanide was not
detected in the water from the barren pond but the sediment from the
pond contained up to 500 mg/1 free cyanide. Liner failures below the
barren, pregnant, and overflow ponds occurred, and free cyanide was
detected in soil cores with free cyanide concentrations up to 300 mg/1.
The maximum depth of free cyanide detection was 61 centimeters (24
inches).
One incident involving heap leach practices has been reported in
Region 7 (R. Rodriguez, California Regional Water Quality Board -
Region 7, personal communication, 1986). At the Piccho Gold Mine,
operated by Can-Gold, Inc., ponded water on top of the heap leach pile
breached a levee and flowed into a collection pond. Can-Gold is
currently involved in subsurface investigations because cyanide was
detected in two ground water monitoring wells. The mining company
claims the cyanide is from previous gold mining activities which also
used cyanide. The subsurface investigation are designed to determine
the source of the cyanide.
Colorado
In the State of Colorado there have been several minor accidents
associated with cyanide heap leaching (M. Loye, Colorado Mined Land
Reclamation Division, personal communication, 1986). Several years ago
four horses died after drinking water from an overflow pond at the
Newport Minerals Site. It was never determined if the horses died from
cyanide poisoning or from caustic soda which had precipitated In the
pond.
The facility at the Ruby Heap Leach site was abandoned without
being reclaimed. During abandonment, the carbon columns were drained
and cyanide flowed around the ponds and into an adjacent ephemeral
drainage. No fish kill was associated with the spill and the flow
never reached the perennial stream.
In 1984, the Cameron Mine owned by Newport Minerals had a cyanide
release after a large storm caused a pond to overflow. The berm failed
on the overflow pond due to inadequate drainage control. The spill
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flowed into the adjacent creek but there was no information on how much
cyanide was released. The concentrations were probably low because of
the large dillution by the stream.
The most recent accident occurred at Neglected Mine owned by Mine
Development Company. The site was permitted as a vat leach but was
operated as a heap leach. A leak was discovered in the liner and
cyanide was released. There was some evidence of cyanide contamination
in the soils.
Idaho
There have been several accidental spills related to heap leaching
practices in the state of Idaho (I. Nautch, Idaho Water Quality Bureau,
personal communication, 1986). Two spills are suspected at the Sunbeam
Mine. The first spill was reported in 1981, three months after the
pond overflow occurred. A followup investigation did not detect any
cyanide problems. The second spill at Sunbeam occurred in the spring
of 1982 when a pond overflowed again. There was evidence of surface
water contamination and a notice of violation was issued by the State
of Idaho.
An accident at the Yellowjacket mine occurred in the spring of
1983. The accident is believed to have been an overflow pond problem.
The overflow occurred before the state inspection, so the amount of
time between the accident and subsequent sampling is unknown. A total
cyanide concentration of 0.29 mg/1 was detected in the surface water.
It is unknown if soil samples were taken at the site. There was also
evidence of a punctured liner in either the barren or the pregnant
pond, which may have resulted in a leak to ground water. Monitoring
wells were installed after cleanup and samples from them contained no
evidence of cyanide.
During 1983 and 1984, the Elk City operation had some leakage
problems in the primary trench leading to the pregnant pond (J.
Moeller, Idaho Department of Health and Welfare, personal communica-
tion, 1986). Samples indicated cyanide contamination of both the
ground water and soil. Ground water analysis showed 9 to 10 mg/1 total
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cyanide, 1 mg/1 weak acid dissociable (WAD) cyanide, and 1 mg/1 free
cyanide. Ground water was contaminated for 30 to 46 meters (100 to
150) feet beyond the problem area. Evidence of soil contamination from
cyanide was found 0.3 meter (1 foot) below the surface. There are no
reports on contamination of vegetation. High total cyanide (6 mg/1)
was found in Elk Creek and the Elk City water supply just downstream.
The leak area was located approximately 120 meters (400 feet) from the
creek. Cleanup costs are estimated at $500,000.
The most recent spill occurred in the spring of 1986 at the
Comeback Mine when a process pond containing a concentration of 200
mg/1 WAD and free cyanide overflowed. The discharge flowed over snow
and ice covered land for approximately 1 kilometer (0.5 mile) before it
reached the stream, where less than 1 mg/1 of free cyanide was
detected. There was no evidence of ground water or soil contamination.
New Mexico
In the summer of 1984, the catchment pond and dam located below
the waste residue pile of the Gold Field Mine overflowed because of
heavy rains (A. Die, New Mexico Environmental Improvement Division,
personal communication, 1986). Total cyanide concentrations of 0.5 to
0.6 mg/1 were detected in several monitoring wells. The pregnant pond
came within several inches of overtopping. No other impacts were
observed.
Montana
The Golden Maple Mine in Gilt Edge is the only raining operation
which has had a problem associated with heap leaching practices in
Montana (D. Smith, Montana Department of State Lands, personal communi-
cation, 1986). During the spring of 1985, the ponds were close to
breaching, so the operation released pond water to prevent destruction
of their dike. The released water contained concentrations of 35 rag/1
total cyanide and 27 mg/1 chlorine amenable cyanide. The released pond
water flowed down a dry streambed and infiltrated the alluvium.
Cyanide was detected in a ground water monitoring well located within
the mine permit area and in a ranch well approximately 0.4 kilometer
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(0.25 mile) away. The highest cyanide concentration measured from
samples from the rancher's well was 0.199 mg/1 total cyanide and 0.14
mg/1 chlorine amenable cyanide in November 1985. The cyanide has since
dissipated. The ground water from the bedrock aquifer was also sampled
but no cyanide was detected.
Nevada
One accident has been associated with cyanide heap leach opera-
tions in Nevada (H. Van Drieun, Nevada Division of Environmental
Protection, personal communication, 1986). Nevex Mining Company had an
operation where the heap leach operations were unfenced. Four cows and
a bull died instantly after drinking the cyanide solution from one of
the process ponds.
Oregon
In Oregon, a heap leach operation was recently abandoned because
the operator had problems with the cyanide process (K. Ashbaker, Oregon
Department of Environmental Quality, personal communication, 1986).
The cyanide solution would not penetrate the ore but continually ran
off the piles. No cyanide has been detected in the ground water or the
surface water.
South Dakota
In May 198A, there was a spill at Wharf Resources at the Annie
Creek mine caused by high rainfall and snowmelt (B. Townsend, South
Dakota Department of Natural Resources, personal communication, 1986).
The upper pregnant and barren ponds overflowed into the overflow pond
which was only clay lined. The released water contained a concentra-
tion of approximately 100 mg/1 total cyanide. The clay liner contained
concentrations of approximately 2 to 3 mg/1 total cyanide, with a
maximum concentration of 14 mg/1 cyanide. At about the same time, a
tear was discovered in the barren pond Hypalon liner. Cyanide solution
seeped into the clay liner below. The tear was repaired and the
contaminated clay was removed.
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Utah
There have not been any problems with the small cyanide operations
in the last 6 years in Utah (C. Dietz, Utah Water Pollution Control
Division, personal communication, 1986). However, there is one large
operation, the Mercur Mine, which has had a problem with their heap
leach pads. The liner under the heap leach pile was constructed with a
sand blanket, geotextile, clay and synthetic liners. The leak
detection system detected 6 x 10 to 1 x 10 cubic meters per second
(1 to 2 gallons per minute) of leach solution containing up to 120 to
130 mg/1 free cyanide. The spraying solution was applied at a rate of
0.01 cubic meters per second (200 gallons per minute). No impacts
occurred because the leak was contained in the leak detection system.
Mercur's second leach pile liner also leaked into the leak detection
system. There are no ground water monitoring wells because the bedrock
is highly fractured. Direction of plume movement is, therefore,
difficult to ascertain.
Washington
There have been no cyanide heap leach operations in Washington.
One operation will be permitted by the beginning of 1987 (B. Lingky,
Washington Department of Natural Resources, personal communication,
1986).
Wyoming
The State of Wyoming has no major cyanide heap leach operations
(C. Bosco, Wyoming Land Quality Division, personal communication,
1986). There are some small operations which have not reported any
problems.
SELECTION OF A CYANIDE ATTENUATION FACTOR FOR CHAPTER 4
The accidental spill of process solution at the hypothetical
mining operation discussed in Chapter 4 occurred during the springtime
as a result of snowmelt combined with a heavy thunderstorm. The
process solution from the pond flowed across the saturated ground,
which was partially snow covered for approximately 1 kilometer (0.5
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mile), and entered a small tributary, which flows about 3 kilometers (2
miles) until it joins a main drainage. Several mining operations have
had similar incidents but usually inadequate data are reported to be
able to calculate the attenuation of cyanide. The only reported
accident having sufficient data was that at the Comeback operation in
Idaho.
At Comeback a release of process solution, with concentrations of
200 mg/1 weak acid dissociable and free cyanide, flowed over the snow-
and ice-covered ground surface for approximately 1 kilometer (0.5 mile)
before it reached a stream (I. Nautch, Idaho Water Quality Bureau,
personal communication, 1986). The flow which entered the stream
contained concentrations of less than 1 mg/1 of free cyanide. The
attenuation of cyanide as a result of flowing over the ground for
approximately 1 kilometer (0.5 mile) was two orders of magnitude.
Based on Broderius's (1977) research on water from different
sources spiked with cyanide ranging from 25 to 200 ug/1, the half-life
for volatilization of HCN is from 0.37 to 2.3 days. Simovic et al.
(1985) found the cyanide concentration of an aerated solution (pH 7 and
4° C) initially at 200 mg/1 was reduced to less than 1 mg/1 after about
230 hours (9.6 days). The decay rate was much higher during the first
80 hours (2.1 mg/1 per hour). Assuming a stream velocity of 0.3 meter
per second (1 foot per second) for the accidental spill discussed
above, the spill would take approximately 3 hours to reach the mouth of
the 3 kilometer- (2-mile) long tribtuary. Using the range from
Broderius, it would take from 6 hours to 4 days more to reduce the free
cyanide content by half after the spill reached the main drainage.
For the accidental spill described in Chapter 4, an attenuation
factor of 2 orders of magnitude is used as the spill flows over the
ground, based on the data from Comeback mine. Since there is no actual
data on the attenuation of cyanide in streams and because experimental
data show volatilization to be a relatively slow process compared to
the stream flow rate, only dilution will be used to decrease cyanide in
streams. Using only dilution factors to reduce cyanide concentration
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in streams is conservative; in actuality, processes such as volatiliza-
tion, reaction of cyanide to ammonia and formate, oxidation, metal
coraplexation, biodegradation, sorption, and formation of simple and
complex compounds should reduce the free cyanide concentration
considerably.
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REFERENCES
Broderlus, S. J. 1977. Personal communication concerning the fate of
cyanides in the aquatic environment. EPA Grand R805291, Dec. 8,
1977. Univ. of Minnesota, St. Paul. As quoted in Callahan et al.
(1979).
Simovic, L., W. J. Snodgrass, K. L. Murphy, and J. w. Schmidt. 1985.
Development of a model to describe the natural degradation of
cyanide in gold mill effluents, jn D. Van Zyl (ed.). Cyanide and
the Environment. Proc. of a Conference. Tuscon, Ariz. Dec.
11-14, 1984. Department of Civil Engineering, Colorado State
University. Fort Collins, Colorado.
U.S. Environmental Protection Agency. 1986. Quantities of Cyanide -
Bearing and Acid-Generating Wastes Generated by the Mining and
Beneficiating Industries, and the Potentials for Contaminant
Release. EPA 68-01-7090 and 68-01-7053.
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