NTEPKM-301811
TECHNICAL RESOURCE DOCUMENT
EXTRACTION AND BENEFICIATION OF
ORES AND MINERALS
VOLUME 6
GOLD PLACERS
October 1994
U.S. Environmental Protection Agency
Office of Solid Waste
Special Waste Branch
401 M Street, SW
Washington, DC 20460
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Technical Resource Document: Gold Placers
DISCLAIMER AND ACKNOWLEDGEMENTS
This document was prepared by the U.S. Environmental Protection
Agency (EPA). The mention of company or product names is not to
be considered an endorsement by the U.S. Government or by EPA.
This Technical Resource Document consists of three sections. The
first is EPA's Profile of the gold placer mining industry; the following
sections are reports on site visits conducted by EPA to gold placer
mines in Alaska. The Profile section was distributed for review to the
U.S. Department of the Interior's Bureau of Mines, the State of
Alaska Department of Natural Resources and Department of
Environmental Conservation, the Interstate Mining Compact
Commission, the American Mining Congress, the Mineral Policy
Center, and public interest groups. Summaries of the comments
received on the draft profile and of EPA's responses are presented as
an appendix to this section. The site visit sections were provided to
representatives of the companies and of state agencies who participated
in the site visit. Their comments and EPA's responses are presented
as appendices to the specific site visit section. EPA is grateful to all
individuals who took the time to review sections of this Technical
Resource Document.
O-
'vTx • The use of the terms "extraction," "beneficiation," and "mineral
X) processing" in this document is not intended to classify any waste
^T) stream for the purposes of regulatory interpretation or application.
Rather, these terms are used in the context of common industry
\f) terminology.
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, IL 60604-3590
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Technical Resource Document: Gold Placers
TABLE OF CONTENTS
Page
1 0 MINING INDUSTRY PROFILE. GOLD PLACERS 1-1
1 I INTRODUCTION . . . l-l
1 2 ECONOMIC CHARACTERIZATION OF THE GOLD PLACER INDUSTRY .. . 1-3
1 2 1 Background 1-3
1.2.2 Current Operations 1-4
1 3 PHYSICAL CHARACTERIZATION OF PLACER DEPOSITS 1-7
1 4 GOLD PLACER MINING PRACTICES 1-12
1.4.1 Background 1-12
1.4.2 Extraction Methods 1-13
1.4.2.1 Open Cut Methods 1-15
1.4.2.2 Other Methods 1-17
1.4.3 Beneficiation Methods 1-21
1.4.3.1 Sizing 1-22
1.4.3.2 Coarse Concentration 1-23
1.4.3.3 Fine Concentration 1-25
1.4.3.4 Mercury Amalgamation 1-27
1.5 WASTE MANAGEMENT PRACTICES 1-29
1.5.1 Extraction and Beneficiation Wastes and Materials 1-29
1.5.1.1 Waste Rock or Overburden 1-29
1.5.1.2 Tailings 1-30
1.5.2 Waste and Materials Management 1-31
1.5.2.1 Tailings Impoundments/Settling Pond Systems 1-32
1.6 ENVIRONMENTAL EFFECTS 1-40
1.6.1 Surface Water 1-40
1.6.2 Ground Water 1-42
1.6.3 Soil 1-43
1.6.4 Wetlands 1-43
1.6.5 Wildlife M3
1.7 MITIGATING MEASURES AND REMEDIATION 1-45
1.7.1 Tailings 1-45
1.7.2 Stream Channel M5
1.7.3 Floodplain 1-46
1.7.4 Soils 1-48
1.7.5 Mined Land Remediation 1-48
1.8 CURRENT REGULATORY AND STATUTORY FRAMEWORK
1.8.1 Environmental Protection Agency Regulations
1.8.1.1 Resource Conservation and Recovery Act
1.8.1.2 Clean Water Act
1.8.1.3 Dredged and Fill Material
1.8.2 Department of the Interior
1.8.2.1 Bureau of Land Management
1.8.2.2 National Park Service and Fish and Wildlife Service
1.8.3 Department of Agriculture (Forest Service)
1.8.4 State Programs
1.8.4.1 Alaska . .
1.8.4.2 Colorado
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1.9 REFERENCES 1-O3
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Technical Resource Document: Gold Pickers
2 0 SITE VISIT REPORTS: ALASKA PLACER MINES ... . .2-1
2 1 INTRODUCTION . . . . . 2-1
2 2 POLAR MINING. INC. . . . . 2-1
2 2 1 General Facility Description 2-1
222 Regulatory Requirements and Compliance 2-9
2 3 ALF HOPEN 2-11
2 3 1 General Facility Description 2-11
232 Regulatory Requirements and Compliance 2-13
2.4 COOK'S MINING 2-15
2 4.1 General Facility Description 2-15
2.4 2 Regulatory Requirements and Compliance 2-17
2.5 REFERENCES 2-19
3.0 SITE VISIT REPORT: VALDEZ CREEK MINE CAMBIOR ALASKA INCORPORATED 3-1
3.1 INTRODUCTION 3-1
3.1.1 Background 3-1
3.1.1.1 General Description 3-2
3.1.2 Environmental Setting 3-6
3.1.2.1 Geology 3-6
3.1.2.2 Surface Water 3-8
3.1.2.3 Ground Water 3-8
3.2 FACILITY OPERATION 3-10
3.2.1 General Overview 3-10
3.2.2 Extraction 3-10
3.2.2.1 Excavation 3-10
3.2.2.2 Water Management 3-12
3.2.3 Beneficiation 3-13
3.2.3.1 Ancillary Facilities 3-16
3.3 MATERIALS AND WASTE MANAGEMENT 3-17
3.3.1 Waste Rock 3-17
3.3.2 Tailings 3-17
3.3.3 Other Materials 3-21
3.4 REGULATORY REQUIREMENTS AND COMPLIANCE 3-24
3.4.1 Federal Permits 3-24
3.4.1.1 Bureau of Land Management 3-24
3.4.1.2 Army Corp of Engineers 3-24
3.4.1.3 Environmental Protection Agency 3-24
3.4.2 State Permits 3-25
3.4.2.1 Dam Safety ' 3-25
3.4.2.2 Diversion Channel 3-26
3.4.2.3 Alaska Fish and Game 3-26
3.4.2.4 Solid Waste Permit 3-26
3.4.3 Inspections and Compliance Incidents 3-27
3.4.3.1 Inspections 3-27
3.4.3.2 Compliance Incidents 3-28
3.5 REFERENCES 3-30
in
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Technical Resource Document: Gold Placers
APPENDICES
APPENDIX 1-A ACRONYMS 1-69
APPENDIX 1-B COMMENTS SUBMITTED BY U.S. BUREAU OF MINES
ON DRAFT GOLD PLACER PROFILE 1-72
APPENDIX 1-C RESPONSE TO COMMENTS SUBMITTED BY U S.
BUREAU OF MINES ON DRAFT GOLD PLACER
PROFILE REPORT 1-74
APPENDIX 3-A COMMENTS SUBMITTED BY CAMBIOR ALASKA INC.,
ON DRAFT SITE VISIT REPORT 3-31
APPENDIX 3-B EPA RESPONSE TO COMMENTS SUBMITTED BY
CAMBIOR ALASKA INCORPORATED ON DRAFT SITE
VISIT REPORT 3-32
APPENDIX 3-C COMMENTS SUBMITTED BY THE STATE OF ALASKA
ON DRAFT SITE VISIT REPORT 3-34
APPENDIX 3-D EPA RESPONSE TO COMMENTS SUBMITTED BY THE
STATE OF ALASKA ON DRAFT SITE VISIT REPORT 3-35
LIST OF TABLES
Page
Table 1-1. EPA and Bureau of Mines Estimates of Operational Placer Mines 1-6
Table 1-2. Turbidity and Arsenic Levels in Two Alaskan Creeks 1-42
Table 3-1. Estimated Volumes of Overburden and Pay-Gravel 3-11
Table 3-2. Theoretical Efficiency of Settling Ponds 3-19
Table 3-3. NPDES Discharge Rates 3-20
Table 3-4. Storage Tank Summary 3-23
IV
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Technical Resource Document: Gold Placers
LIST OF FIGURES
Page
Figure 1-1 Overview of a Placer Mining Operation . . 1-16
Figure 1-2 Long Tom . 1-19
Figure 1-? Basic Design for a Prospector's Rocker 1-20
Figure -4 Diagram of a Trommel . ... 1-23
Figure -5 Diagram of a Sluice Box Including Hungarian Riffles 1-24
Figure -6 Diagram of a Jig 1-26
Figure -7 Diagram of a Centrifugal Bowl 1-27
Figure -8. Diagram of a Pinched Sluice 1-28
Figure -9. Pre-Settling Ponds 1-34
Figure -10 Sediment Removal Before Ponds by Filtration 1-35
Figure -11. Settling Ponds with Tailings Filters 1-36
Figure -12. Settling/Recycle Pond 1-38
Figure 2-1. Polar Mining, Inc., Vicinity Map 2-2
Figure 2-2. Sketch of Lower Goldstream Creek Mining Operation 2-4
Figure 2-3. Plan View of Lower Goldstream Creek Operation, Amended 1992 2-6
Figure 2A. Second Plan View of Lower Goldstream Creek Operation, Amended 1992 2-7
Figure 3-1. Facility Location Map 3-3
Figure 3-2. Denali Mine Work Areas 3-4
Figure 3-3. Typical Cross Section of Pits A-6 Through A-10 3-7
Figure 3-4. Water Balance for 1990 Through 1991 3-15
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Mining Industry Profile: Gold Plactn
1.0 MINING INDUSTRY PROFILE: GOLD PLACERS
1.1 INTRODUCTION
This Industry Profile presents the results of U.S. Environmental Protection Agency (EPA) research
into the domestic gold placer mining industry and is one of a series of profiles of major mining
sectors. Additional profiles describe lode gold mining, lead/zinc mining, copper mining, iron mining,
and several industrial mineral sectors, as presented in the current literature. EPA prepared these
profiles to enhance and update its understanding of the mining industry and to support mining
program development by states. EPA believes the profiles represent current environmental
management practices as described in the literature.
Each profile addresses extraction and beneficiation of ores. The scope of the Resource Conservation
and Recovery Act (RCRA) as it applies to mining waste was amended in 1980 when Congress passed
the Bevill Amendment, Section 3001(b)(3)(A). The Bevill amendment states that "solid waste from
the extraction, beneficiation, and processing of ores and minerals" is excluded from the definition of
hazardous waste under Subtitle C of RCRA (40 CFR 261.4(b)(7)). The exemption was conditional
upon EPA's completion of studies required by RCRA Section 8002(f) and (p) on the environmental
and health consequences of the disposal and use of these wastes. EPA segregated extraction and
beneficiation wastes from processing wastes. EPA submitted the initial results of these studies in the
1985 Report to Congress: Wastes from the Extraction and Beneficiation of Metallic Ores, Phosphate
Rock, Asbestos, Overburden From Uranium Mining, and Oil Shale (U.S. EPA 1985a). In July 1986,
EPA made a regulatory determination that regulation of extraction and beneficiation wastes under
Subtitle C was not warranted (51 FR 24496; July 3, 1986). EPA concluded that Subtitle C controls
were unnecessary and found that a wide variety of existing Federal and State programs already
addressed many of the risks posed by extraction and beneficiation wastes. Instead of regulating
extraction and beneficiation wastes as hazardous wastes under Subtitle C, EPA indicated that these
wastes should be controlled under Subtitle D of RCRA.
EPA reported their initial findings on wastes from mineral processing from the studies required bv the
Bevill Amendment in the 1990 Report to Congress: Special Wastes From Mineral Processing (U S
EPA 1990). This report covered 20 specific mineral processing wastes; none involved gold
processing wastes. In June 1991, EPA issued a regulatory determination (56 FR 27300) stating that
regulation of these 20 mineral processing wastes as hazardous wastes under RCRA Subtitle C is
inappropriate or infeasible. These 20 wastes are subject to applicable state requirements. Any
mineral processing wastes not specifically included in this list of 20 wastes no longer qualifies for the
exclusion (54 FR 36592). Due to the timing of this decision and the limited number of industry
wastes at issue, gold placer processing wastes are not addressed in this profile.
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Mining Industry Profile: Gold Placers
In addition to preparing profiles, EPA has undertaken a variety of activities to support state mine
waste programs. These activities include visits to a number of mine sites; compilation of data from
State regulatory agencies on waste characteristics, releases, and environmental effects; preparing
summaries of mining-related sites on the National Priorities List (NPL); and an examination of
specific waste management practices and technologies. EPA has also conducted studies of State
mining-related regulatory programs and their implementation.
The purpose of this profile is to provide additional information on the domestic gold placer mining
industry. The report describes gold placer extraction and beneficiation operations with specific
reference to the wastes associated with these operations. The report is based on literature reviews
This report complements, but was developed independently of, other Agency activities, including
those described above.
This report briefly characterizes the geology of gold placer deposits and the economics of the
industry. Following this discussion is a review of gold placer extraction and beneficiation methods;
this section provides the context for descriptions of wastes and materials managed by the industry, as
well as a discussion of the potential environmental effects that may result from gold placer mining.
The profile concludes with a description of the current regulatory programs that apply to the gold
placer mining industry as implemented by EPA, Federal land management agencies, and selected
States. The profile section is followed by reports on site visits conducted by EPA to gold placer
mines in Alaska.
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Mining Industry Profile: Gold Placers
1.2 ECONOMIC CHARACTERIZATION OF THE GOLD PLACER INDUSTRY
1.2.1 Background
Placer gold is typically sold in one of two forms. Nuggets may be sold to jewelry makers, the
general public, or other users directly. An unknown amount of gold production enters the market
directly by sales to the jewelry industry, and thus, may never be reported as typical production from
some small operations. Individual pieces are typically assessed an additional charge or "nugget
bonus" in addition to the gold market price. Placer gold may also be smelted, and pass into the
market through the same route as lode-mined gold (U.S. EPA 1988b).
Gold mining began in the United States in the early 1800s in North Carolina and soon followed in
Georgia and Alabama in 1829 and 1830, respectively. Although not a state until 1850, gold mining
was also conducted in California as early as the late 1700s. California was not a major gold producer
until the gold rush began with the discovery of gold at Sutler's Mill in 1848. As gold prospectors
moved west, mining also commenced in other states. Production in California between 1850 and
1864 averaged nearly 2.45 million troy ounces annually. After the rich, readily accessible placer
deposits were mined out, gold was extracted using drift mining techniques and later, hydraulic
methods. Hydraulic methods were limited after 1884. In the late 1890s, dredges were employed to
mine alluvial placers, a practice that continued steadily through the 1960s, and intermittently through
the 1980s (Clark 1970; Silva 1986).
Placer gold deposits were known to exist in Alaska prior to its purchase by the United States in 1867,
but these deposits were not exploited until California gold rush prospectors eventually commenced
operations in Alaska as they moved up the coast. By 1940 Alaska led the states in gold production,
supplying 750,000 troy ounces of gold, mostly from placer mines. During World War II, domestic
placer mining activity subsided substantially and remained at a low level after the war because of
rising operating costs and a government-fixed gold price of $35 per troy ounce. When the federal
restrictions on prices and private ownership of gold were relaxed and the market price of gold
increased in the late 1970s, there was a resurgence in gold mining activity including placers (U.S.
EPA 1988a).
During the 1800s, and early into this century, gold mining of alluvial deposits primarily involved
placer methods. Miners worked stream deposits using a variety of techniques and recovered gold by
gravity separation and mercury amalgamation. In Alaska, mining quickly exhausted the high-grade
gold deposits, but the introduction of new extraction techniques made it possible for miners to
successfully access lower-grade deposits, as well as to increase the overall productivity of placer
mining. Large-scale permafrost thawing, hydraulic stripping, and mechanized excavation methods
were some of the innovative extraction techniques that modernized the industry. In 1905, mechanical
dredges reached Nome, Alaska, and in the 1920s, mining operations in the same region began to
work with large electric-powered dredges (U.S. EPA 1988a).
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Mining Industry Profile: Gold
Gold recovery methods and efficiency have continued to evolve over the years with the refinement of
techniques, equipment and technology Before the 1940s, miners were able to recover up to 60% of
the gold values within a deposit. By 1945, recovery rates were between 70 and 75 percent.
Currently, miners interviewed during EPA's recent site visits claimed that, depending on the type of
operation, over 90 percent of gold may be recovered from a deposit. As efficiency has gone up, so
has the difficulty level in extracting the remaining deposits (Silva 1986).
1.2.2 Current Operations
According to U S Bureau of Mines statistics, placer mines have historically produced approximately
35 percent of the total U.S. gold production. However, while net gold production has increased
annually in recent years, placer production has decreased as the readily accessible deposits have been
mined out and with the increase and improvement in heap leaching technology. Placer mines
produced only two to three percent of the total U.S. gold production during the period from 1984
through 1989; in 1990 and 1991, placer production accounted for approximately one percent of the
U.S. total. According to Bureau of Mines statistics, placer mines produced 2,888 kg of gold in 1991
while total U S. gold production was approximately 289,885 kg (U.S. DOI, Bureau of Mines 1988a;
U S DOI, Bureau of Mines 1992a; Lucas 1992).
The economics involved in mining a deposit is dependant on factors including the cost of fuel, interest
rates, and the market price of gold. These factors are variable in terms of location and time. Under
1991 conditions, gold placer mines could economically beneficiate gravels containing as little as 0.49
grams per cubic meter (0.01 oz/cubic yard). However, average recoverable gold content of precious
metals from placer gravels was 0.82 gm/m3 (0.02 oz/yd3) of material washed. (U.S. DOI, Bureau of
Mines 1992a).
The size and nature of placer mines range from open cut operations disturbing tens of acres annually
to small sluices operated solely as a recreational activity. In 1987, the average number of employees
at placer mines in the contiguous 48 states was between three and four, and few mines employed
more than 10 people (U.S. EPA 1988b). The size of a placer mining operation determines whether
or not it is subject to compliance with the Clean Water Act administered by the Environmental
Protection Agency (EPA) under 40 CFR 440 Subpart M. Mines handling less than 1,500 cubic yards
of ore per year and dredges handling less than 50,000 cubic yards annually are exempted from the
effluent guidelines (40 CFR, Part 440, Subpart M 1989). A more complete discussion of regulatory
issues is presented in the current regulatory framework section of this report.
Regardless of size, most placer mines throughout the country operate on a seasonal basis (ADEC
1986; U.S. EPA 1988a). The small size of most placer operations and the relative ease in
establishing an operation make placer mines particularly sensitive to fluctuations in market prices;
more mines are active when prices are up and fewer are active as prices drop. These facts contribute
to the difficulty in establishing the number of mines operating at any one point in time (U.S. EPA
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.Mining Industry Profile: Gold Placers
1988a). Additionally, the limited information collected by state and federal agencies, and the sources
that these agencies use to determine the number of operational mines, make specific characterization
of the placer mining industry exceedingly difficult.
Alaska has the highest concentration of operational placer mines and is the only state where gold
production from placer operations exceeds that from lode operations. In 1991, according to the
Alaska Department of Natural Resources, Alaskan mines (202 placer and 2 hard rock mines)
produced 7,585 kg of gold. Production from placer and hard rock mines was not differentiated. The
number of placer mines operating in 1991 dropped to 202 from the 218 reported in 1990. Low gold
prices, exhaustion of resources and increasing regulatory requirements were cited as reasons for the
decrease. The 202 placer mines operating in Alaska in 1991 employed 1,240 people, although this
number is adjusted for a 260 day work-year (Alaska Department of Natural Resources 1992b). Half
of the placer gold produced in Alaska in recent years comes from just two mines; Valdez Creek mine
and Green's Creek mine. The remaining 200 mines produce an average of 500 ounces per year. The
average grade is .0158 ounces per yard, so that the average in-place value of Alaskan pay gravels is
just over $5.00 a yard or about $3.00 per ton. Stripping overburden costs between $1 and $2 a yard
at most mines, depending on site specific conditions. The low grade of placer ores is the reason the
placer industry is a small business or family oriented industry. Major mining companies with high
capitalization costs can not operate placer ground at a profit (Peterson 1993).
The Bureau of Mines also collects and publishes data based on results collected from a voluntary
survey. Data collected during the 1988 survey showed that placer mines operated in a number of
states including Alaska, Idaho, Montana and Nevada (U.S. DOI, Bureau of Mines 1989a; U.S. DOI,
U.S. DOI, Bureau of Mines 1989b; U.S. DOI, Bureau of Mines 1989c; U.S. DOI, Bureau of Mines
1989d). Placer mines have also operated in Oregon on at least a limited basis (U.S. DOI, Bureau of
Mines 1992a).
Data from a previous survey (U.S. EPA 1985b) indicated that there were four operating placer mines
in Colorado; 29 in Idaho (mostly seasonal); one in California (processing 4.5 x 10 6 ton/year) and 46
in Montana (most probably seasonal or intermittent). These were based upon state agency records
and permit files.
Bureau of Mines publications typically withhold figures for placer production by state to protect
proprietary information and do not provide specific lists of gold placer mines. Of the 19 placer
operations that responded in 1991, 14 were considered in the underground, small-scale mechanical
and hand methods or suction dredge category. The other four were bucketline dredging operations
(U.S. DOI, Bureau of Mines 1992a). A 1986 survey conducted by the EPA, based on data collected
from state agencies, showed a total of 454 placer mines in operation (U.S. EPA 1988b). The same
year, the Bureau of Mines reported 207+ operational placer mines (U.S. DOI, Bureau of Mines
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Mining Industry Profile: Gold Placers
•-
1986). The number of placer mines operating in each state in 1986, as tabulated by EPA and the
Bureau of Mines, is presented in Table I-1
Table 1-1. EPA and Bureau of Mines Estimates of Operational Placer Mines
State
Alaska
Idaho
Montana
California
Colorado
Oregon
South Dakota
Wyoming
Washington
Utah
Nevada
TOTAL
EPA Estimate1
190
69
57
26
13
49
18
8
16
5
3
454
Bureau of Mines Estimate2
195
2
6
2
0
Several
0
0
1
0
1
' 207 +
1 (U S. EPA 1988b).
: (U.S. DOI, Bureau of Mines 1986).
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Mining Industry Profile: Gold Placers
1.3 PHYSICAL CHARACTERIZATION OF PLACER DEPOSITS
Placer deposits are mineral bearing deposits found in weathered residuum and alluvium. The word
placer is of Spanish derivation, used by early miners i'n North and South America to describe the gold
found in gravels and sands associated with streams. For the most part, placers are unconsolidated
sedimentary deposits, although, depending on the nature of the associated materials, placers may be
cemented to varying degrees. Placers occurring within permafrost are usually frozen solid (Boyle
1979). Current placer mining activity generally takes place in young placers originating as
watenvorked sediments or stream deposits.
There are several natural requirements necessary before a placer deposit can form: there must be a
valuable mineral which is relatively heavy and resistant to weathering and abrasion; the valuable
mineral must be released from its parent rock; and the valuable mineral must be concentrated into a
workable deposit (usually by water transport). Although the location, size, and shape of a placer will
reflect the regional forces of erosion, transportation, and deposition which created it, its final form
will be controlled or modified by purely local conditions. As a result, each placer deposit can be
expected to be unique in one or more ways. The end richness and size of a placer deposit will
depend more on there being an abundant supply of source materials, and on conditions favorable for
their concentration, than on the actual richness of the primary source. (Wells 1973)
Gold particles in placer deposits range in size from 'flour' gold (-400 mesh) found in Idaho's Snake
River, to the massive, 2516 troy ounce 'Welcome Stranger' nugget found in Victoria, Australia.
Although the value of a placer deposit is generally based on smaller particles (called colors), nuggets
are the perceived rewards for a miner's toils and are associated with placers. Nugget formation is not
fully understood: some are larger remnants of lode deposits that have become part of a placer deposit,
while others apparently form in place within streams where dissolved gold precipitates on either a
gold particle or other nucleus. Although nugget formation may occur within streams, placer gold
often has a platy (i.e., tabular) form (Boyle 1979; MacDonald 1983).
The density of gold, and its resistance to chemical weathering, are two principal factors for the
development of gold placer deposits. Gold is considerably more dense than the minerals typically
associated with it (19.13 grams per cubic centimeter [g/cc] versus 2.65 g/cc for quartz). Heavy
minerals typically settle to the bottom of a stream or beach displacing lighter material. Gold
continues a downward migration in response to additional agitation within the streambed. Settling
action also occurs on land in colluvium although the downward migration is not as pronounced as the
absence of a fluid matrix. Placer deposits are formed as particles accumulate in this manner (Park
and MacDiarmid 1975).
The distance gold particles move within a stream (or by gravity) is dependant on the size and shape of
the particle, and the energy of the stream. Large particles will settle close to their source while the
smallest may travel great distances. Particles are often deposited in riffles and other irregularities
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Mining Industry Profile: Gold Placers
within the streambed where the energy and velocity of the stream are reduced (Park and MacDiarmid
1975)
Particles that are carried great distances in streams are typically more pure than the lode deposits
from which they came. The increase in purity is a result, in part, of the dissolution of impurities
within the gold particle (Boyle 1979). It has also been observed that the oxidized portion of lode
deposits, (that which is also most likely to become placer gold), is often of greater purity than the
primary deposit. Fineness is a measure of purity in gold with 1.000 being absolutely pure. Gold in
placers ranges from 0.500 to 0.999 fine; most is greater than 0.850 fine (Boyle 1979).
Placer gold is different in appearance than gold deposited in veins. Crystallization on the surface of
placer particles dull the luster normally associated with vein deposits. Placer deposits may be colored
brown or black if coated with manganese and iron oxides or manganese and iron humates; or white to
gray when coated with calcium carbonate or colloidal clay (Boyle 1979).
The terms pay streak, pay dirt and pay gravel refer to the zone where the economic concentration of
gold is located. The pay zone is often found in the layer adjacent to the bedrock, but under certain
conditions the pay zone may be located on the surface or in one or more intermediate layers (Wells
1973). Finer gold particles are carried farther from their source and have a greater tendency to be
distributed throughout the sediments in which they are found. The value of the pay streak is usually
assessed as troy ounces per cubic yard, and varies throughout the deposit (Boyle 1979).
Placers exist in different forms although they all originate from lode deposits. Placer deposits may be
young (modern) or ancient (fossil). Young deposits are usually found along present day water
courses and were formed during the Quaternary (Recent and Pleistocene Epochs) and late Tertiary
Periods. Young deposits range from a few feet to more than 10 feet in thickness (U.S. EPA 1988a).
Ancient deposits occur in paleochannels and are usually buried by layers of sediment or volcanics. In
the Sierra Madre of California, lava that filled ancient stream channels now forms residual ridges as
material adjacent to the lava has been eroded away (Park and MacDiarmid 1975). Some of these rich
fossil placers have been identified in tertiary gravels buried beneath up to 1,500 feet of sediment
(Hatkoff 1983). Ancient deposits in Alaska may be 10 to 40 feet thick, buried under 10 to 30 feet of
humus, sand, silt and clay (U.S. EPA 1988a). Other ancient placers have been located in
northwestern Wyoming and the Deadwood formation of South Dakota. Ancient placers in the
contiguous 48 states are not typically mined since expensive underground mining techniques are often
required (Boyle 1979).
Alluvial placers form when material is concentrated in stream channels. For this reason they are also
referred to as stream or fluvial placers. Alluvial placers were likely to have been man's first source
of gold. It is speculated that sheepskins may have been placed in streams to trap gold bearing
sediments, adding new insight to the myth of Jason's golden fleece (Boyle 1979). Alluvial placers are
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Wining Industry Profile: Gold Placers
formed in sedimentary deposits as gold is picked up where currents are fast and deposited where the
stream velocity slows. Alluvial deposits are not restricted to channels and may be deposited at the
mouths of streams and rivers. Most significant placer deposits in the U.S. are of alluvial origin
including those in the Sierra Nevada region of California (Boyle 1979).
Alluvial gold placers are associated with a wide range of minerals depending on the geology of the
lode deposits from where they came. The gold, or electrum, may be naturally alloyed with other
metals such as copper, iron, lead, silver and zinc. In addition, minerals containing varying
concentrations of copper, iron, lead, silver and zinc have been found with gold placer deposits as
have monazite, pyrite, arsenopyrite and wolframite. 'Black sands', associated with placer deposits in
many areas, consist of heavy minerals including magnetite, ilmenite and members of the garnet group
(ADEC 1986: Ferguson and Gavis 1972; Thompson 1992).
The characteristics of different alluvial or stream placers varies considerably, but generally they can
be divided into several categories based on the size of the stream (Wells 1973). Gulch placers are
characteristically small in area, have steep gradients and are confined to minor drainages in which a
permanent stream may or may not exist. This type of placer is made up of poorly sorted gravel.
Boulders are usually found in quantities that preclude all but simple hand mining methods. Creek
placers are found in permanent streams and are composed of a mix of gravels, cobbles and boulders.
Generally the size and number of boulders in creek placers is less than in gulch placers. Creek
placers are important sources of gold. River placers are similar to creek placers but the gold is
usually finer, the gravel well-rounded and large boulders few or absent. Over-all river placers are
generally low-grade, but local pay streaks and bedrock concentrations may be able to support large-
scale mining operations.
Alluvial placer deposits are currently the most economically significant in the U.S. and will be the
focus of this profile. Other forms of placers, including flood gold, bench, beach, eluvial, desert,
eolian, and glacial placers will also be discussed briefly below.
As a rule, finely-divided gold travels long distances under flood conditions. This gold, which can
best be referred to by the miners' term of "flood gold," consists of extremely minute particles and is
found far from its original source. Flood gold will be deposited near the surface of a sand bar
between the high and low water mark on the inside bend of the stream. Good surface showings of
fine-size gold are not uncommon, but often the gravel a few inches beneath these surface
concentrations is nearly worthless. With few exceptions flood gold has proven .economically
unimportant in spite of its deceptively rich surface concentrations. However, such deposits may not
be permanently exhausted by mining since floods deposit a new supply of gold and the renewal will
continue indefinitely. In some cases small-scale mining operations are able to skim the new
accumulations of flood gold from the same location year after year, however more ambitious plans to
mine the deeper gravels have generally proved unprofitable. (Wells 1973)
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Mining Industry Profile: Gold Placers
Bench placers are usually remnants of deposits formed during an earlier stage of stream development
and left behind as the stream cuts downward. The abandoned segments, particularly those on the
hillsides, are commonly referred to as "bench" gravels. Frequently there are two or more sets of
benches in which case the miners refer to them as 'high" benches and "low" benches. Bench placers
have been mined in the past using underground mining methods and following the development of
hydraulic mining in the 1850s. many of the larger benches were worked by hydraulicking and the
smaller ones by ground sluicing. (Wells 1973)
Beach placers are also formed by water action, but in this case gold is eroded by wave action from
deposits along a shoreline or reworked from sediments carried to the sea by nearby rivers and
deposited within the beach materials. Some beach placers are being, or have recently been, mined
around Nome, Alaska, usually by dredging (Boyle 1979). Typical beach placers are found as
erratically distributed, somewhat lenticular concentrations or streaks of black sand minerals with
varying amounts of finely-divided gold. Those found along active beaches are the result of storm and
tidal action, and they come and go with the changing conditions of the beach (Wells 1973). Beach
placers may be either submerged or elevated due to sea level fluctuations of the past.
Eluvial placers have been referred to as residual deposits. The distinction between eluvial and other
forms of placer deposits is that these deposits have been concentrated in place, as the lighter,
valueless surrounding material has been leached or eroded away. Deposits formed on a slope as a
result of gravity-driven downhill creep are included in the definition of eluvial deposits although these
deposits may also be referred to as colluvial (Hatkoff 1983; Macdonald 1983). Eluvial deposits were
worked in the Appalachians of Georgia as well as in California, Oregon, Nevada and Montana (Boyle
1979; Hatkoff 1983; Macdonald 1983). Considering the relative ease in mining these deposits, most
of the economically significant deposits have been mined out.
Desert placers are so different from normal stream placers as to deserve a special classification.
Desert placers are found in arid regions where erosion and transportation of debris depends largely on
fast-rising streams that rush down gullies and dry washes following summer cloudbursts. During
intervening periods, varying amounts of sand, gravel or hill-side detritus is carried in from the sides
by lighter, intermittent rain wash which is sufficient to move material into the washes but not carry it
further. When the next heavy rain comes, a torrential flow may sweep up all of the accumulated
detrital fill, or only part of it, depending on intensity and duration of the storm and depth of fill. The
intermittent flows provide scant opportunity for effective sorting of the gravels or concentration of the
gold. Under such conditions the movement and concentration of placer gold will be extremely
erratic. Moreover, where the entire bedload is not moved, any gold concentration resulting from a
sudden water flow will be found at the bottom of the temporary channel existing at that time. This
may be well above bedrock. As a result, gold concentrations, if present at all, may be found in one
or more discrete lenses or layers scattered throughout the gully sediments and the best chance of
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Mining Industry Profile: Gold Placers
finding pay gravel is to a great extent fortuitous and largely dependent on careful prospecting. (Wells
1973)
Eolian placers are also found in arid or desert regions, but where the wind acts as the agent of
concentration. By blowing sand and the lighter rock particles away from a body of low-value
material the wind may leave an enriched surface veneer containing gold in a somewhat concentrated
state (Wells 1973) Eolian placers differ from most other placers in that the gold has been
concentrated in place by the removal of other less valuable material rather than by being transported
to a new location where it is concentrated and deposited. There is no reference to eolian placers
being mined in the U.S. World-wide, the limited extent of these deposits generally does not warrant
specific exploration or development (Macdonald 1983).
Glacial placers are deposited as a result of glacial activity. The nature of glacial movement, however,
tends to mix materials to such an extent that without subsequent fluvial activity, mining is not an
economically viable option. On the other hand, it is not unusual for a miner to assert that a particular
deposit, particularly if its origin is obscure, is a "glacier" placer. Occasionally bits of rich but widely
scattered float have been found in glacial moraines but because the gold is mixed with large masses of
barren earth attempts to mine the moraines are rarely successful. One reference was made to the
mining of a glacial placer near Fairplay, Colorado. Here the actual moraines were mined locally but
the most extensive and productive placers were found in outwash aprons extending away from the
true moraines. Where outwash aprons were mined, the glacial materials were reworked by running
water and were not a true glacial placer, however since glacial rivers choke themselves and build up
their channels progressively, their deposits are likely to be thicker and not so well concentrated as
those of the more normal graded rivers which are not associated with glaciers. (Wells 1973)
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Mining Industry Profile: Geld Placers
1.4 GOLD PLACER MINING PRACTICES
1.4.1 Background
Typically a placer mine moves up-valley so that settling ponds and water runoff will be down gradient
from the wash plant. Often the original stream is relocated to a temporary channel during the period
of mining In addition, the previously mined ground cannot be immediately reclaimed since it is
necessary to maintain a drain below the operation. Miners have also found that it is almost
impossible to control all of the water that comes into the mine from the side hills and the cut above
the wash plant creating the potential for prolonged erosion and down-stream environmental impacts.
Once the mine has ceased operations, the miner is then faced with the need to reclaim large tracts of
stream valley with no more prospect of additional income from the property.
Recently two popular mining methods have been developed that make reclamation easier. One is the
"Koppenberg" method in which the wash plant is highly portable. In this method, the wash plant is
continuously moved to the pay dirt instead of the pay dirt being moved to the plant. In this method,
the size of each mining cut is the length of the back-hoe arm that feeds the plant. No great mounds
of tailings are generated because the tailings are backfilled into the previous hole as the plant moves
along. This method works extremely well in narrow valleys but does not work well in frozen ground
(Peterson 1993).
A second new method, effective in mining large open cut mines is to mine down-valley instead of the
standard up-valley method. This means that the recycle pond and settling basin is up hill from the
cut. The result is they can much more easily control the amount of water coming into and escaping
from the operation, and they can reclaim the old cuts as they mine down-valley away from them.
Since they are not needed to maintain an open drain, there is no reason for the open cuts to be left
unreclaimed. A critical part of the reclamation plan is to plan for the position of the stream at the
end of mining (Peterson 1993).
Gold placer mining consists of three major operational steps: extraction, beneficiation and
processing. Extraction is defined as removing ore material from a deposit and encompasses all
activities prior to beneficiation. Beneficiation is the operation by which gold particles are separated
from the associated undesirable material. Beneficiation in placer mining usually involves gravity
separation techniques. Processing operations, including smelting, produce a final, marketable product
bullion from the gold concentrate produced in beneficiation. Most gold placer mining has been
conducted using surface techniques, although some underground drift mining of placers occurred
historically.
At a typical placer mine, overburden is removed to expose the pay zone. In some permafrost areas,
or where other conditions require it, the pay zone is blasted to fluff-up the material and make it easier
to excavate. The gold bearing gravel is then hauled by trucks to a wash plant, which consists of a
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Mining Industry Profile: Gold Placers
combination of equipment used to size and concentrate the pay dirt. A typical wash plant consists of
a grizzly where initial sizing takes place and extreme oversize material is rejected. A trammel then
M7es ihe remainder of the plant feed. The pay dirt is then washed into a sluice or sluices, where the
gold and other heavy minerals are concentrated and settle below the riffles and onto matting. The
gold remains in ihe sluice, while the tailings and wash water flow out of the sluice and into a tailings
or settling pond The number and configuration of settling ponds varies depending on site specific
conditions. The purpose of the settling ponds is to allow the solids to settle out prior to recycling the
water back to the wash plant. The ponds may also serve to reduce the sediment load in any
remaining water prior to discharge. Periodically, (on the order of 1 - 2 days) the wash plant is shut-
down and the gold is removed. The concentrate may then be subjected to further, more refined
concentration, with gravity separation techniques such as jigs, shaking tables and pinched sluices, and
possibly magnetic separation if magnetite is present, to produce a high grade concentrate suitable for
processing.
Mercury amalgamation was used to collect fine gold in the lowest (final) portion of a sluice.
Regulations and environmental concerns have all but eliminated this procedure, except for the recent
mention of a few very specialized operations, which employ mercury amalgamation. These
operations function such that mercury is not allowed to escape into the environment (Thompson
1992). Otherwise, more efficient operations utilizing gravity separation have generally replaced
mercury amalgamation.
1.4.2 Extraction Methods
Extraction methods employed at gold placer operations differ substantially from hard rock extraction
methods. Although many placer gold operations are fairly small, relatively large amounts of
overburden, waste rock, and gold bearing gravel must be excavated and concentrated to remove the
trace constituent gold. The stripping ratio, which is defined as the amount of overburden and waste
rock moved relative to the amount of pay dirt mined, at gold placer mines is high. At the largest
placer gold mine in North America, Cambior, Inc.'s Valdez Creek Mine near Cantwell, Alaska,
approximately 34,000 cubic yards of material were extracted daily. Of this, 3,000 cubic yards pass
through the wash plant when it is operating, leaving approximately 90 percent of the material moved
as waste. The figures for this mine site suggest a stripping ratio that approaches 10:1 (waste:ore).
Other Alaskan gold placer mines had stripping ratios of 4:1 and 3:1. In the coldest regions where
gold placer mining occurs, frozen overburden (consisting of vegetation, muck, and waste rock) and
gold bearing deposits must be loosened by blasting and/or mechanical means prior to extracting the
pay dirt. They may also be thawed by a system or grid of water pipes circulating over the deposit.
Many gold placer operations are located in extremely cold climates and remote areas. These
conditions increase the difficulty of mining and associated cost of equipment maintenance. (U.S.
EPA 1988a)
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Mining Industry Profile: Gold Placers
Gold extraction at placer operations may be conducted using either surface or underground
techniques, but surface methods are most commonly used because they generally are the least
expensive (Whiteway 1990). The principal surface extraction method associated with large-scale gold
placer operations is open cut mining, which is synonymous with open pit mining; for the purposes of
this study, the term "open cut" will be used. Other extraction methods employed at gold placer mines
include dredging, hydraulicking, and other recreational and small-scale extraction techniques, such as
panning and small suction dredging. Currently, use of dredging and hydraulicking methods is
limited. Underground mining methods include bore-hole and drift mining, which in the past have
been employed to reach deep deposits. (Alaska Miner's Assn. 1986; Argall 1987)
An anicle on drift mining in the Engineering and Mining Journal (Argall 1987) states that the
prohibitive cost of mining deep shafts and long adits has prevented a major revival of drift mining.
However, in Alaska there may be a resurgence in this type of mining. A few years ago nearly 100
percent of the placer mining operations used surface mining methods. However, in Alaska the
industry trend toward underground placer mining suggests that use of, and dependence on,
underground placer mining techniques may increase in the future. (Alaska Miner's Assn. 1986; U.S.
EPA 1988a; Argall 1987; ADEC 1992)
Historically, large-scale gold placer mining operations used hydraulic methods to excavate the pay
rone. Underground drift mining methods developed in the early 1900s were also used to reach rich
placer deposits located far below the surface. With the advent of mechanical methods of extracting
and hauling materials, hand, hydraulic, and drift mining extraction methods were displaced by mobile
earth-moving equipment that was capable of handling greater volumes of material. The increase in
the volume of material mined compensated for the decline in the grade of deposits (Alaska Miner's
Assn. 1986). Prior to 1930, excavation equipment at open cut gold placer mines was steam-powered,
but the development of the diesel engine revolutionized the industry both in Alaska and in other placer
mining states. New equipment in the mid-1930s reduced costs and increased the volume of material
handled. This allowed previously uneconomical deposits to be mined. Concurrent improvements
were made in gravel washing and recovery systems. Technological advancements in placer mining
methods generally offered operators increased flexibility and efficiency.
The selection of mining methods that maximize gold recovery and allow the safe, efficient, and
economic removal of the pay dirt is influenced by several factors. The choice of mining methods is
based on the physical characteristics of the placer deposits (dip, size, shape, depth, degree of
consolidation), the water supply, and, ultimately, the available funds. A gold placer mining operation
will usually employ a combination of extraction methods because of the variety of conditions that
must be addressed. (Whiteway 1990; U.S. EPA 1988a; Alaska Miner's Assn. 1986)
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Mining Industry Profile: Gold
1421 Open Cut Methods
The surface mining method most commonly used in placer mining is open cut. Modern earth-moving
equipment is used to mine deposits of varying size and depth. Characteristics of the deposit such as
topography and condition of the underlying bedrock are important. While open cut mining is the
most common method used to extract placer gold, specifics on the frequency of use of this type of
surface mining relative to other mining methods are not known. (Alaska Miner's Assn. 1986)
Open cut mining involves stripping away vegetation, soil, overburden, and waste rock to reach the
ore buried below. In the placer industry, the pay zone or pay streak is the equivalent of ore and may
be referred to as either pay dirt or pay gravel, depending on the nature of the deposit. The pay steak
can be excavated by bulldozers, loaders, scrapers, and draglines; conveyors or trucks transport the
pay dirt to a wash plant for beneficiation. Usually the excavation site is located upstream or upslope
of the wash plant, and the direction of the mining activity is away from the plant. Once a cut has
been mined, it is generally either backfilled with excavated overburden and waste rock or converted
to a water recycle or sediment pond (see Figure 1-1). (ADEC 1987)
Bulldozers are used in every phase of open cut gold placer mining operations from initial excavation
to final reclamation. Primary functions include the following: stripping overburden (typically
composed of vegetation, muck, and barren gravels; pushing pay gravels to sluice boxes for
beneficiation; and stacking tailings. They are typically equipped with straight blades. In addition.
some are fitted with rippers to break up cemented gravels and excavate bedrock containing placer
gold deposited into fractures and joints. Bulldozers are also used to construct roads, diversion
ditches, and settling ponds (U.S. EPA 1988a; Cope and Rice 1992; Alaska Miner's Assn. 1986).
Second to bulldozers, front-end loaders are the next most commonly utilized piece of equipment at
gold placer mines. Front-end loaders are used to excavate loose or already ripped gravel. Most
front-end loaders are mounted on wheels with rubber tires, but they can also be mounted on tracks.
The rubber-tired loader is faster than a track loader, but it is less efficient when digging compacted
in-situ gravels. (Cope and Rice 1992)
Draglines are used to excavate both dry gravels and underwater gravels, but when employed at open
cut gold placer mining operations, draglines perform the same function as bulldozers (i.e., stripping
overburden, moving excavated material, stacking tailings, etc.) Draglines may be fitted with booms
as long as 100 feet, which gives them a large digging radius. Although it costs less per unit to move
materials using draglines, they are not as mobile as bulldozers. Draglines are fitted with buckets
whose capacities range from 1/2 to 2 cubic yards. A disadvantage posed by draglines is the sparse
number of experienced operators. It is not clear from the information available whether draglines are
more commonly used to extract dry gravels at placer gold surface mines or to dredge underwater
gravels. (Cope and Rice }992; U.S. EPA 1988a)
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Mining Industry ProfUt: Gold Placers
A
B
C
D
E
F
G
H
I
J
K
L
M
Mining cut.
Cut drainage (Gam to pond*).
Owtburdan.
washing, sizing, and recovery plant.
Settling pond.
Recycle pond.
Recycla pup and pipeline to
Flooculant addition.
Polishing pcnd.
Final •ffl.uMRt (goa* bade to
Figure 1-1. Overview of a
Mining Operation
(Source: ADEC 1987)
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Mining Industry ProfU*: Gold
1 4 2.2 Other Methods
Dredging
Although dredges are used m both surface mining and underwater mining of placer deposits, they are
generally associated with the mining and beneficiation of metal-bearing minerals (values) below water
level Dredges are limited by the availability of a saturated placer gold deposit or the existence of a
water table near the surface to create the appropriate excavating environment (i.e., a pond). Some
dredges, however, operate in the water while anchored on land. Four commonly used dredging
systems include bucketlme (also referred to as bucket-ladder), backhoe, dragline, and suction
dredging. Dredges are designed to execute multiple functions. For example, many floating dredges
are equipped to perform extraction, beneficiation, processing, and waste disposal. (U.S. EPA I988a;
Alaska Miner's Assn. 1986) Hydraulic dredging systems have been used to produce sand and gravel,
marine shell deposits for aggregate, and mine deposits containing diamonds, platinum and tin. Heavy
mineral mining, including titanium sand dredging is also practiced to obtain ilmenite, monazite, rutile
and zircon (Harty and Terlecky 1986).
Dredging systems are categorized as either hydraulic or mechanical, depending on the method of
digging. Hydraulic systems include suction dredges, while mechanical systems comprise bucketline,
backhoe, and dragline dredges. Some dredging systems integrate hydraulic and mechanical power for
the purposes of extracting placer gold. Special circumstances might make a combination dredge
(sometimes called a "combiminer") more desirable than simply a plain suction dredge. Some suction
dredges are equipped with a cutter head to make excavation easier. Dredges are known to be capable
of excavating to depths of 225 feet, but excavation for mineral recovery has been much less, perhaps
one quarter of that depth.
Hydraulic Methods
In hydraulic mining, or hydraulicking, water under pressure is forced through an adjustable nozzle
called a monitor or giant and directed at a bank to excavate gold placer pay streak and to transport it
to the recovery unit, which is generally a sluice box. The pressurized water jet can also be used to
thaw frozen muck and to break up and wash away overburden. Water pressure is supplied either by a
pump or by gravity. The operator controls the vertical and horizontal movements of the monitor
(giant, or water cannon), as well as the water pressure and the volume of the flow by remote control
(U.S. EPA 1988a).
One advantage of hydraulicking is the ability to move large volumes of material at a low cost. The
amount of water required to accomplish this movement and the resultant tailings, however, present a
serious obstacle to the widespread use of this water-dependent extraction technique. Originally
employed in geographic areas rich with water bodies, hydraulicking tapered off as mechanized eanfc-
moving extraction equipment gained favor and as restrictions were placed on the availability and
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Mining Industry Profile: Gold Placers
pollution of water. Given the efficiency and economic savings of the equipment used in open cut gold
placer mining operations and concerns related to hydraulic mining's environmental impacts, it seems
unlikely that hydraulic mining will be widely used in the future. (U.S. EPA 1988a)
Small-Scale Methods
Small-scale extraction methods include panning, and suction dredging. Small-scale extraction
methods are primarily used by recreational gold placer miners working on a non-commercial scale.
Small-scale methods combine extraction and beneficiation steps because the extraction phase of the
placer operation is integrated with beneficiation. Essentially, shallow alluvial sediments are "sifted"
using equipment that is modeled after the basic mining equipment used in some open cut and dredging
operations; small-scale extraction methods employ the basic principles of gravity separation. (U.S.
EPA 1988a)
Panning recovers gold concentrate. It is a low budget, labor intensive method involving fairly
rudimentary gravity separation equipment. Panning is also a sampling method used by prospectors to
evaluate a placer gold deposit to determine whether it can be mined profitably. Such assessment
operations differ from small-scale mining operations that recover gold for an immediate return on
their investment. (U.S. EPA 1988a; Alaska Miner's Assn. 1986) Small-scale gold placer miners also
use a variety of other portable concentrators, including long toms, rocker boxes, and dip boxes (see
Figures 1-2 and 1-3). (U.S. EPA 1988a)
Small suction dredges are being used successfully by recreational or small (part-time) gold placer
ventures. A pump varying from one to four inches usually floats immediately above the mined area.
The mechanism that recovers the gold sits in a box next to the suction pipe and is carried under
water. Alternatively, the nozzle has two hoses, one that transports water to the head and the other
that transports material to the surface of a beneficiation device (i.e., usually a small sluice box that
deposits tails back into the stream).
Underground Mining Methods
Drift mining and bore-hole mining are terms applied to working alluvial placer deposits by
underground methods of mining. Drift mining is more expensive than open cut sluicing and
hydraulicking, so it is used only in rich ground. In drift mining, the pay streak is reached through a
shaft or an adit. Pay dirt that has been separated from the gold bearing zone either by blasting or
with hand tools is carried in wheelbarrows or trammed to small cars that transport the gravel to the
surface for beneficiation. If a deposit is large, then regular cuts or slices are taken across the pay
streak, and work is generally performed on the deposit in a retreating fashion from the inner limit of
the gravel. (U.S. DOI 1968; Argall 1987)
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Mining Industry Profile: Gold Placers
iGravtl ond water enter here
Perforated screen
Lined with 1/8-inch
sheet iron
Lined with
2 1/8-inch sheet
(Source: U.S. EPA 1988)
Figure 1-2. Long Tom
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Mining Industry Profile: Gold Placers
Hoppar bottom. 24-gagt
gatvanutd iron. H" holts
on iycifittrs\
0
ELEVATIONS
(apron rtmovad)
24 f age galvamztd iron
SECTION
APftON
Figure 1-3. Basic Design for a Prospector's Rocker
(Source: U.S. EPA 1988)
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Mining Industry Profile: Gold Plasers
1.4.3 Beneflciation Methods
Beneficiation of placer materials involves the separation of fine gold particles from large quantities of
alluvial sediments. Gravity separation is the most commonly used beneflciation method. Magnetic
separation is used in some operations to supplement the gravity separation methods. Water is used in
most, if not all steps, initially, to wash gold particles from oversized material and later, to move gold
concentrate through the wash plant. The wash plant refers to the collection of equipment where
heneficiation is conducted. For land-based operations, the plant may be stationary but is often
mounted on skids so that it can be moved along with the mining operation as it progresses. Dredge
operations frequently employ floating wash plants, where the beneflciation equipment is carried within
the dredge.
Beneficiation typically involves three general steps: the first is to remove grossly oversized material
from the smaller fraction that contains the gold, the second to concentrate the gold, and the third to
separate the fine gold from other fine, heavy minerals. The same type of equipment is often used in
more than one step, for example an array of jigs may be employed to handle successively finer
material (Flatt 1990).
Classification (sizing) is the initial step in the beneflciation operation when the large, oversize material
(usually over 3/4 inch) is removed during beneflciation. A rough (large diameter) screen is usually
used. This step may be fed by a bulldozer, front-end loader, backhoe, dragline or conveyor belt.
Within the industry, this step is also referred to as roughing (U.S. EPA 1988a). Previous studies
have indicated that the practice improves the efficiency of gold recovery and reduces the water
consumption (Bainbridge 1979).
After the initial removal of the larger material during sizing, pay dirt is subject to a coarse
concentration stage. This step, also referred to as cleaning, may employ trommels or screens. Other
equipment used in the coarse concentration stage includes sluices, jigs, shaking tables, spiral
concentrators and cones. Depending on the size of the gold particles, cleaning may be the final step
in beneflciation (Flatt 1990; Silva 1986).
Fine concentration is the final operation used to remove very small gold values from the concentrate
generated in the previous stages. Many of the previously identified pieces of equipment can be
calibrated for finer separation sensitivity. Final separation uses jigs, shaking tables, centrifugal
concentrators, spiral concentrators or pinched sluices.
The following is a summary of the equipment commonly used in beneflciation. One of the key
determinants in selecting equipment is the volume of material that will pass through each step within a
given time period. Rates for material handling for the equipment discussed below are included where
the information was available.
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Mining Industry Profile: Gold Placers
1 4 3.1 Sizing
Sizing is a physical separation of material based strictly on size. The sizing step removes large rocks
prior to additional beneficiation. The waste generated is usually solid and is much lower in volume
compared to the pay dirt that passes through. Discharge material may be used for other applications
including road aggregates. This step typically involves the pay dirt being loaded into a grizzly,
trammel or screen or a combination thereof.
A typical grizzly consists of a large screen or row of bars or rails set at a specific distance apart (2 to
6 inches) such that undersized (gold-bearing) material can readily pass through while oversize material
is rejected. Typically, the grizzly would be inclined to ease the removal of the rejected material.
Water is usually used to move material through the grizzly and wash off any fines that may be
attached to larger fragments before they are discarded. The undersized material drops onto a
trammel, screen, or sluice depending on the operation. Grizzlies may be stationary or vibrating (U.S.
EPA 1988a).
Trommels are wet-washed, inclined, revolving screens (Figure 1-4). They usually consist of three
chambers, the first uses a tumbling action and water to break up aggregated material. Successive
chambers are formed of screens or punched metal plates (smaller holes first) that allow the selected
sized material to pass through. The screens are typically 3/8 inch in the second chamber and 3/4 inch
in the final chamber. Material passing through the screens is directed for further concentration.
Material passing through the trammel may be returned for a second pass or discarded (Cope and Rice
1992; U.S. EPA 1988a).
A fixed punchplate screen (also called a Ross Box) consists of an inclined plate with holes ranging
from 1/2 to 3/4 inches. Pay dirt is placed onto the plate where nozzles wash the material with a high-
pressure water stream. The undersized (desirable) material is washed to the outside of the plate
where it is fed into a sluice designed to handle 3/4 inch material. The oversize is directed down the
plate which typically has riffles to collect coarser gold. Oversized material passing off the plate is
discarded.
Screens function to separate oversized, undesirable material from the gold concentrate. Screen size
(usually 1/2 to 3/4 inch) is selected based on pay dirt characteristics. Screens may be fixed or
vibrating. The action of both is similar although vibrating screens speed the rate of particle
separation. The concentrate continues for further concentration while the oversize is removed via a
chute or stacker conveyor belt. Different sized screens may be used to sort material into different
sizes for use as road construction aggregate or other purposes.
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Mining Industry Profile: Gold Plac,en
FRONT VIEW
ORE ENTERS
FROM FEED
HOPPER OR
OTHER
CLASSIFICATION
DEVICE
SIDE VIEW
SPLASH PLATE
SCREENED OR SLOTTED
SECTION _
WATER SUPPLY TO
WATER BAR
CHAIN DRIVE
INTERNAL BAFFLES
DESIGNED TO
INCREASE TURBULENCE
COARSE MATERIAL
TO TAILS SLACKER
WET FINES FALL THROUGH
TO SCREEN OR SLUICE BOXES
Figure 1-4. Diagram of a Trommel
(Source: EPA 1988a)
1 4.3.2 Coarse Concentration
Separation in the coarse concentration step involves particle density rather than size. Sluices are the
pieces of equipment most commonly used in the coarse concentration step although jigs and screens
may also be employed. The wastes are discharged to a tailings pond also called a recycle pond or
settling pond. Most of the material that enters the sluice exits as waste. The gold and other heavy
minerals settle within the lining material while the lighter material is washed through. Coarse
concentration generates the largest volume of waste during beneficiation.
A sluice consists of a long, narrow, inclined trough lined with riffles, perforated screens, astroturf,
corduroy, burlap or a combination thereof (Figure 1-5). The sluice mimics the conditions that caused
the formation of the placer deposit initially. Pay dirt is placed at the high end of the trough and
washed with a stream of water. Gold and other dense minerals settle between the riffles or in the
lining while the lighter material is carried through the sluice. Longer sluices are used for preliminary
concentration. Shorter, wider sluices are used following preliminary separation to separate fine gold
from black sands. The length, grade, riffles and lining are adjusted to suit the nature of the pay dirt
However, slopes of one to two inches per foot are typical.
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Mining Industry Profile: Gold Placers
oat AND WATER
AT SUCK PLATE
0010 AND -BLACK SAMM-
ASTNO-TURF
CAHPET
STEEL BOTTOM
'ATE* AMI COAJISC MATEMAL
TO 8ETTUNQ PONDS
SUCK KATE
SBtVKW
^**W
WATCH AND COARSC MATCMAL
Figure 1-5. Diagram of a Sluice Box Including Hungarian Riffles
(Source: EPA 1988a)
Riffles are bars, slats, screens or material that act to create turbulence and variation of water flow
within the sluice. This action increases the efficiency of gravity separation. Riffles have ranged in
size from 12 inches wide, 12 inches high and 12 inches apart to 1 inch high, 1 inch wide and 2 inches
apart.
Hungarian riffles are angle irons mounted perpendicular to the sluice box. The vertical angle of the
angle irons may be adjusted to affect the degree of turbulence generated and maximize gold
deposition. Astroturf, carpet or coconut husks are sometimes placed between and under the riffles to
maximize their efficiency. The units are usually constructed so that sections of the riffles may be
removed so the gold can be recovered from the turf. As mentioned above, the height, spacing and
construction of the riffles may be adjusted to maximize efficiency of gold separation depending on the
character of the pay dirt.
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Mining Industry Profile: Gold Plaaers
Other material has also been tested and/or used as riffles and liners. Expanded metal riffles are
employed at some operations. Like the Hungarian riffles, the height, size and spacing is determined
by the pay dirt and, sections are removable for cleaning. Miscellaneous materials including
longitudinal or horizontal wooden poles, blocks, rocks, railroad ties, cocoa mats, rubber and plastic
strips have also been documented as being used as riffles by different placer operations (U.S. EPA
1433 Fine Concentration
Alter the pay dirt is concentrated, typically through a trommel and sluice, most waste material has
been removed leaving a fine concentrate (the percentage of gold within the concentrate is not
discussed in the references and is highly variable). The concentrate may then be subjected to fine
concentration methods including jigs, shaking tables and pinched sluices. Depending on the nature of
the concentrate and the equipment, 80 to 95 percent of the gold can be recovered from the concentrate
at this stage. The waste at this stage is a slurry (often called slimes), and is low in volume compared
to that generated in the other stages.
Jigs are settling devices that consist of a screen through which water is pulsed up and down via a
diaphragm or plunger numerous times per second (Figure 1-6). A layer of rock or steel shot referred
to as ragging may be placed on the screen to accentuate the up and down motion. Slurry is fed above
the screen. The agitation keeps the lighter material in suspension which is then drawn off. The
heavier material falls onto or through the screen and is collected as concentrate. Efficiency is
increased by varying the inflow rate, pulse cycles and intensity. Jigs may handle from 7 to 25 tons
per hour, and can handle particles ranging from 75 mm to 25 mm. At some operations, jigs are also
employed in the cleaning stage. (Macdonald 1983; Silva 1986).
Shaking tables consist of small riffles over which a slurry containing fine pay dirt is passed. The
gold settles into the riffles and, through a vibrating action, is directed to one side of the table where it
is collected. The tails are passed across the middle of the table or remain in suspension. Middlings.
material that is partially settled, may be collected. Heads and middlings are commonly reprocessed
on multi-stage tables. Shaking tables can handle materials from 15 urn to 3.0 mm (U.S. EPA 1988a;
Macdonald 1983).
Spiral concentrator is a generic term referring to a method of separation rather a specific piece of
equipment. Pay dirt concentrated from previous steps is fed with water, into the top of the spiral.
and spins down through the spiral. The heaviest materials are concentrated toward the center of the
spiral while lighter material moves to the outside. Gold particles (concentrates) are collected from the
center of the spiral while the tails pass down the entire spiral. Large operations may employ multiple
spiral concentrators in series to handle a wide range of sizes. Humphreys concentrators, as one
example, can be used to separate particles between 100 Mm and 2 mm in diameter. These machines
can handle low feed rates (1.5-2 tons per hour) and low feed density (U.S. EPA 1988a).
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Mining Industry Profile: Gold Placers
FEED
FEED
- • ••••„-»••»•«
•«••:.- ••••::
• o»
WATER
C^V TAILINGS
LAYER OF STEEL
SHOT
(R«ffinf)
^ SCREE
CONCENTRATE
FLEXIBLE
DIAPHRAGM
CONCENTRATE
OUTLET
J TAILINGS
Figure 1-6. Diagram of a Jig
(Source: Cope 1992)
Centrifugal concentrators or bowls were typically used in dredges but may also be used in other
operations (Figure 1-7). Slurry is fed into the top of the circular machine. Driven from the bottom,
the interior portion spins on its vertical axis, driving the slurry against a series of concentric circular
riffles or baffles. The lighter material (tails) is.driven up the side of the bowl while the heavy
material (concentrate) collects on the bottom or in the riffles (Cope and Rice 1992).
Pinched sluices work on the concept that as a fine feed is exposed to an opening, the arc formed by
the heaviest particles dropping will be much narrowed than the arc formed by the lighter materials
(Figure 1-8). A divider placed perpendicular to and below the pinched outfall lets heavy materials
(concentrate) collect on one side while lighter material (tails) can be collected and reprocessed
separately or directed out of the operation completely. Reichert cones, which are based on the
pinched sluice principle, can handle 75 tons per hour and recover particles in the minus 10 to plus
400 mesh range (45 urn to 0.5 mm) (Gomes and Martinez 1983).
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Mining Industry Profile: Gold Platers
FEED
TAILINGS
r LAUNDER
WATER JACKET
WATER INLET
HOLES
CONCENTRATE-^
DRAIN
Figure 1-7. Diagram of a Centrifugal Bowl
(Source: Cope 1992)
Magnetic separation is not commonly used in placer mining but may be employed when magnetite is a
component of the black sand. This technique is used to remove electrostatically charged tails from
the neutral gold. To be effective, the method should involve multiple magnetic treatments followed
by demagnetization steps so that the magnetite is removed slowly, not in a 'magnetically coagulated'
form that may bind gold particles within it. Magnetic separation, when used, is one of the final steps
of beneficiation. This technique is used in at least one operation in Alaska; the extent of its use in
gold recovery from construction aggregates in California was not discussed (Thompson 1992).
1.4.3.4 Mercury Amalgamation
Before Federal environmental regulations were promulgated in the mid-1970s, mercury amalgamation
was commonly used to recover gold fines. An amalgam of mercury and gold is formed by adding
mercury to the lowest portions of a sluice. There had been little or no reference to its recent use until
an article in the Engineering and Mining Journal entitled "Byproduct Gold From Construction
Aggregates" mentioned its use in recovering gold from bowl concentrates. In this case, gold
concentrates were generated as a byproduct from the production of construction aggregates. The
amalgam was to produce a final bullion. The mining and beneficiation operations were not described
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Mining Industry Profile: Gold Placers
Sluice
Fan
Feed box
Splitter
blades
Concentrate ^ ft Tailings
Middlings
Figure 1-8. Diagram of a Pinched Sluice
(Source: Macdonald 1983)
in the article. The only discussion regarding control of environmental releases simply stated that the
operation was conducted away from the mining activities (Thompson 1992).
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Mining Industry Profile: Gold Placers
1.5 WASTE MANAGEMENT PRACTICES
This section describes several of the wastes and materials that are generated and/or managed at gold
placer extraction and beneficiation operations and the means by which they are managed. As is noted
in the previous section, a variety of wastes and other materials are generated and managed by gold
placer operations
Some, such as waste rock and tailings, are generally considered to be wastes and are managed as
such, typically in on-site management units. Even these materials, however, may be used for various
purposes (either on- or off-site) in lieu of disposal. Some quantities of waste rock and tailings, for
example, may be used as construction or foundation materials at times during a mine's life. Many
other materials that are generated and/or used at mine sites may only occasionally or periodically be
managed as wastes. These include mine water removed from underground workings or open pits,
which usually is recirculated for on-site use but at times can be discharged to surface waters. Some
materials are not considered wastes at all until a particular time in their life cycles.
The issue of whether a particular material is a waste clearly depends on the specific circumstances
surrounding its generation and management at the time. In addition, some materials that are wastes
within the plain meaning of the word are not "solid wastes" as defined under RCRA and thus are not
subject to regulation under RCRA. These include, for example, mine water or process wastewater
that is discharged pursuant to an NPDES permit. It is emphasized that any questions as to whether a
particular material is a waste at a given time should be directed to the appropriate EPA Regional
office.
The first subsection below describes several of the more important wastes (as defined under RCRA or
otherwise) and nonwastes alike, since either can have important implications for environmental
performance of a facility. The next subsection describes the major types of waste units and mine
structures that are of most environmental concern during and after the active life of an operation.
1.5.1 Extraction and Beneficiation Wastes and Materials
1.5.1.1 Waste Rock or Overburden
Waste rock consists of material that contains no gold and must be removed to access the pay zone
Industry usually refers to overburden and, in the case of underground mines, mine development rock
as waste rock. It is generally disposed of in waste rock dumps near the point of excavation.
Eventually, the stockpiled waste rock may be used to backfill the mine cut during reclamation.
Because the desired material (gold) is such a small fraction of the material mined (< 0.1 oz/ton)
there is a tremendous amount of waste rock generated. Surface mining operations generate more
waste per unit of crude ore extracted than underground operations, although stripping ratios var> trom
one site to the next. For example, in 1992 at Polar Mining, Inc.'s Lower Goldstream placer
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Mining Industry Profile: Gold Placers
operation near Fairbanks, Alaska, approximately 2,200,000 cubic yards of overburden were excavated
to beneficiate 500,000 cubic yards of pay dirt. Polar Mining, therefore, has a stripping ratio that
exceeds 4 1 (waste:ore). On the other hand, estimates from the 1992 Reclamation Plan and Annual
Placer Mining Application of another Alaska placer mine (Alf Hopen's Little Eldorado Creek
operation in the Fairbanks mining district near Geary, Alaska) for total material mined and total
material concentrated (70,000 cubic yards and 60,000 cubic yards, respectively) suggest a very low
ratio of overburden to pay dirt (Polar Mining, Inc. 1991b).
Overburden removed from the mine cut is stored nearby, sometimes piled along the edge of the pit
until mining ceases, at which time the waste rock is returned to the cut, or backfilled. These piles
may be referred to as waste rock piles. %
1.5.1.2 Tailings
Material from gravity concentration operations consist of a slurry of gangue (non-gold material) and
process water which passes through the concentration operation. Tailings are classified by their size
into three classes: coarse or oversize tailings, intermediate tailings (middlings), and fine tailings
(slimes). Of the three grades delineated, fine tailings can be further broken down into two categories.
Components of the slurried tailings can be classified as settleable solids* which are made up of sand
and coarse silt, or as suspended solids, composed mostly of fine silt and some clay size particles.
(U.S. EPA 1988a)
Oversize tailings are separated from smaller material early during classification. Open cut operations
use a grizzly to segregate larger material as the pay dirt enters the wash plant. Coarse tailings may
be used in road and filtration dam construction or may be sold as aggregate. Middlings and fines
generated during sluicing are usually disposed of in tailings impoundments. Ultimately, the smaller-
size tailings may be covered by coarse tailings and overburden during reclamation.
Large volumes of flowing water are used to carry the pay dirt through the classification operation.
The velocity of the flowing water generates a large volume of intermediate and fine tailings in the
form of suspended sediment and lesser quantities of dissolved solids. Historically, the water and
sediments were released to streams and created problems downstream from the mining sites.
Currently, release of sediment is controlled by using impoundment structures where the water is held
and the velocity is consequently reduced. As flow is restricted sediments are deposited. Exposure of
waste rock and pay dirt during extraction and beneficiation greatly increases the likelihood that
soluble constituents will be dissolved. Once in solution, dissolved solids are much more likely to pass
through sedimentation structures and reach surface waters.
Recycling or recirculating water at gold placer mines reduces the volume of effluent to be discharged
after treatment. Water treatment is more economical when less water is flowing through the system.
Production statistics from 1984 show that 21.3 percent of the Alaska gold placer mining industry
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Mining Industry Profile: Gold Placers
achieved 90-100 percent recycle of the process wastewater (Harty and Terlecky I984a). Operations
that separate oversize tailings prior to sluicing typically use less water than mines that do not classify
the excavated material (Harty and Terlecky 1984b). Where classification methods are used,
approximately 1,467 gallons of water per cubic yard of pay dirt are needed, whereas at mines that do
not classify material, average water usage is 2,365 gallons per cubic yard of pay dirt. (U.S. EPA
I988a; ADEC 1987)
Chemicals are not typically used during beneftciation at placer gold mines, so tailings contain the
same constituents found in the extracted pay dirt. Very little use of any chemicals was found at
placer sites visited by EPA in 1992. Potential natural constituents of gold placer wastes and materials
include minerals that contain mercury, arsenic, bismuth, antimony and thallium as well as the
minerals pyrite and pyrrhotite. These are often found in discharges from placer mines, however the
Bureau of Mines states that because of the maturity of most alluvial deposits, the majority of the
elemental constituents contained in these minerals are not readily soluble, especially in the
conterminous forty-eight states. Some chemicals associated with gold placer mines have been
identified, and these exceptions involve the addition of chemicals during beneficiation. Some
California operators use magnetic separation to remove high concentrations of magnetite. At early
placer mines, mercury was frequently added to sluice boxes to augment the recovery of fine gold.
Mercury amalgamation produced a slurry waste composed of a mercury-tainted solution and gangue.
Modern placer operations in California have recovered mercury from the sediments as a byproduct of
historic amalgamation operations. The use of mercury at modern gold placer mines is considered
minimal. (U.S. EPA 1991; Cope and Rice 1992)
1.5.2 Waste and Materials Management
Waste and non-waste materials generated as a result of extraction and beneficiation of gold placer
deposits are managed (treated, stored, or disposed) in discrete units. For the purposes of this report,
these units are divided into two groups: (1) waste rock piles and (2) tailings impoundments, also
referred to as settling and recycle ponds.
In general, the goal of treating or managing these materials is to separate the silt and fine-grained
solids from the water, reusing the water or ensuring it meets NPDES discharge requirements prior to
discharging to a stream. Most management occurs after sluicing; the stacking of overburden and
waste rock in areas proximate to the mining operation, however, constitutes an interim method of
managing solid extraction wastes prior to their ultimate return to the mine cut. (Alaska Miner's Assn.
1986)
There are two ways to maximize the quality of the effluent discharged from a gold placer operation.
The effluent can be treated using a variety of impoundments (tailraces, pre-settling ponds, and
settling/recycle ponds), filtration, and, in rare instances, flocculants. A study sponsored by the EPA
in 1984 showed that polymer-aided settling removed over 96-99+ percent of suspended solids using
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Mining Industry Profile: Gold Placers
catiomc polymers (Harty and Terlecky 1984c). Alternatively, the mining operation can be modified
to reduce water use during beneficiation, thereby reducing the volume of effluent discharged.
Management methods used to achieve this reduction include classification, recycling, use of a bypass,
and control of water gam (i.e., surface and subsurface seepage). (Alaska Miner's Assn. 1986)
1521 Tailings Impoundments/Settling Pond Systems
Tailings (oversize, intermediate, and fines) are typically managed in tailings impoundments or used
for construction. The method of managing tailings is largely determined by the water content of the
tailings. Tailings impoundments associated with gold placer mines are generally unlined containment
areas for wet tailings in the form of slurries.
At most gold placer operations, the disposal of tailings requires a permanent site with adequate
capacity for the life of the mine. The size of tailings impoundments varies between operations; that
is, if the impoundment is going to function effectively, the dimensions and characteristics are tailored
to meet the specifications for a particular operation.
The removal of sediment from water is the goal of effluent treatment. A properly designed settling
pond can remove 99 percent of the settleable solids (SS) from the effluent. There are numerous
factors that influence how efficiently a settling pond removes sediment from effluent, including the
following:
• Surface area of the pond
• Flow rate through the pond
• Settling characteristics of the sediment
• Short circuiting
• Entrance and exit effects
• Wind and rain turbulence.
To promote settling, the surface area of the pond should be as large as possible. The flow rate
through the pond can be minimized by means of a bypass that diverts excess water around the
operation. Sealing ponds are designed to meet the needs of a specific placer mining operation. Short
circuiting occurs when the slurry in the pond flows directly from the inlet to the outlet without using
the available settling area. Berms or baffles can be constructed in the pond to eliminate short
circuiting, or the inlet and outlet structures can be positioned far apart from each other. Entrance and
exit effects occur when the velocity of the incoming effluent creates a turbulent plume in the pond. If
the slope of the tailrace is decreased or if a berm is situated at the entrance perpendicular to the flow.
entrance effects can be eliminated. (ADEC 1987; Alaska Miner's Assn. 1986)
Tailraces and Pre-Settling Ponds
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Mining Industry Profile: Gold Placers
The tailrace is the open channel that carries the effluent from the beneficiation plant to the settling
pond. A pre-settling pond is an area of the tailrace that has been widened and deepened two to three
feet to form a small pond in which heavy sediment settles and is temporarily stored. Pre-settling
ponds are smaller than settling ponds, and they are less expensive to build. Pre-settling ponds require
regular cleaning to remain effective, but the frequency of cleaning depends on pond size. To prevent
bulldozers and other heavy equipment from getting stuck during cleaning, the pre-settling pond should
be located on flat, competent bedrock, with a gentle slope on one side of the pond. When the
beneficiation plant shuts down between shifts effluent in the pre-settling pond drains off completely,
allowing for easy cleaning. A small berm of course tailings placed at the downstream end of the
tailrace slows the flow velocity during plant operation, thereby maximizing sediment removal, while
still allowing for the complete drainage of the pre-settling pond after the shift. (Alaska Miner's Assn.
1986; ADEC 1987)
Tailraces and pre-settling ponds are characteristic of open cut surface mining operations. Even at
open cut mines, however, there are variations of the typical tailrace and pre-settling pond. Two pre-
settling ponds are sometimes used sintultaneously and in series to provide extra storage in case the
first pond fills prematurely or in the event that a scheduled cleaning is missed. Alternatively, two
parallel pre-settling ponds might be used at alternating times (see Figure 1-9). (Alaska Miner's Assn.
1986; ADEC 1987)
Filtration
Filtration of sediments can occur at two stages during management. Prior to reaching the settling
pond, the tailings slurry is routed through coarse tailings, which enhance the percolation rates.
Tailings filters are constructed at sites that use fixed or mobile wash plants; the latter have coarse
tailings stackers that deposit the tailings in the mine cut downstream from the direction of mining (see
Figure 1-10). (ADEC 1987)
Filtration also occurs just prior to discharge of the effluent into a receiving stream. Settling ponds in
series may have porous dikes or dams constructed of middlings or coarse tailings (see Figure 1-11).
The more coarse the tailings, the higher the percolation rates will be. Water levels in ponds fluctuate,
rising when the wash plant is actively beneficiating and falling when the plant is shut down. Tailings
filters dampen flow surges through the pond, filter out solids, and mix effluent with ground water,
which decreases the concentration of solids and turbidity. Finally, vegetative filtration can "polish"
the effluent after other treatment methods have removed all settleable solids. (ADEC 1987)
Settling Ponds
Settling ponds are containment areas designed to remove solids from effluent through simple settling
(ADEC 1987). These structures are similar in form and function to tailings impoundments and are
used primarily by large-scale placer operations. Settling ponds are usually created by constructing a
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Mining Industry Profile: Gold Placers
D
E
F
G
H
I
Motes
1
Sluice box (or other primary gold r
Tailings sunp.
Pre-settling pond (2 to 3 feet
water flow through the pond).
Narrow, shallow baza of coarse tailings.
very systea) •
with 1 ft2 surface area per gpo
Second pre-settling pond (when two ponds are used in series).
Disposal area (for sediment renewed from pre-settling ponds).
Alternate pre-settling ponds (when two ponds are used in parallel—
sized at 1 Ct2/gp« water flow).
To meandering tailrace.
(to divert water into one pre-settling pond or the other).
Pre-settling ponds should be located in areas of competent bwln»-Jc or
firm ground to prevent equipment from getting stuck during cleaning.
Pre-settling ponds, and tailraces where passible, should be bounded
by at least one gentle slope so ssdiasnt can be renewed by dozer,
loader, baddies, or dragline.
Mhsn lgcg*»d near flattened tailings pile, sediment from the pre-
settling ponds can be placed on top of the tailings piles as the
cleaned, thereby minimizing handling and rehabilitation
Pre-*ettling pcnds should be built so that water will drain
processing stops. The optiaun tine for sediaent renoval is after
several hours of draining, coanonly at the start of the next shift.
Vten two pre-settling ponds are used in parallel, only one should be
used at a fci«» while the other drains and is cleaned. Flow can be
controlled by «"•" betas appropriately placed in the tailings
Figure 1-9. Pre-Settling Ponds
(Source: ADEC 1987)
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Mining Industry Profile: Gold Placers
9
e
e
o
A
B
C
D
E
F
G
Note
Sluice box (or otter primary gold recovery device).
Tailings soap.
Alternating roue of coarse and fine tailings (placed parallel to flew
path).
Tailraoe (to settling ponds).
tail!
Mobile washing plant (with
Settling pond.
Pile* of coarse tailing* (from stacker).
jigs stacker).
The tailings filter for a fixed plant is ideally constructed entirely of
coarse tailings to enhance the percolation rate. Fine tailings are used
only uhen insufficient coarse tailings are available.
Figure 1-10. Sediment Removal Before Ponds by Filtration
(Source: ADEC 1987)
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Mining Industry Profile: Gold Placers
Kg?
A
B
C
D
Incoming flow (from upstream settling or recycle ponds)
Settling or polishing ponds.
Porous HI VPS (made of Tnorf-iiim to coarse tailings).
Effluent (to further treatment or discharge).
Figure 1-11. Settling Ponds with Tailings Filters
(Source: ADEC 1987)
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Mining Industry Profile: Gold Placers
dam composed of tailings across the downstream end of the mined cut. When the next cut is mined,
most of the extracted sediment is captured in this new pond. Thus, as mining progresses, a series of
ponds emerge. Often the main recycle pond remains intact. Settling ponds should be accurately sized
and should provide for the sum of the following:
• Sediment storage volume
• Retention time volume
• Storm surge volume. (ADEC 1987)
According to the Alaska Department of Environmental Conservation, settling ponds have a length to
width ratio of 2:1. Narrow ponds are less effective at removing sediment because water flows more
rapidly through the pond, scouring and resuspending the sediment. Ponds should be distant from the
bypass and should have adequate emergency spillways to minimize potential damage from floods.
Multiple ponds (i.e., ponds in series) generally provide better treatment than one large pond.
Settling/recycle ponds in combination remove sediment from process water before it is returned to the
wash plant for reuse (Figure 1-12).
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Mining Industry Profile: Gold Placers
5 F
B
C
0
E
F
G
H
I
Flow from upstmaa pre-aettling or settling
sediment as passible has bean removed.
Coarse tailings bera to dissipate energy of incoming water.
ttein recycle pond.
Dike (to prevent short circuiting through pond) .
Peninsula on which recycle pump is located (so
not ****"» a» i]»fr^ at r*T) •
Impermeable (as much as possible) dike.
Outlet structure (see Figures 10A and 10B for details) .
Polishing pond.
Recycle pipeline (to washing plant) .
pcnda where as nuch
floating debris will
Notes
1
Short-circuiting across a pond can be avoided by placing outlets
across from inlets and/or by using berms or baffles to control flow
paths.
The water velocity entering the pond can be decreased by reducing the
slope of the tnllmnB as it enters the pond or by placing some
boulders or large rocks where water enters the pond as shown above.
Spillways should be located away from recycle pump(s) to lessen the
threat of damage froa high water;
The puop should be set on the end of a ««»n (lO-foot) peninsula
jutting out into the pond. This will allow the wind to blow floating
sticks and debris back and forth in the pond without causing **•• to
SfQO^BHLLLSteS d2TO^O^^L Cutt DUD^9 ^J^C^uGB*
A floating boom or net can »IQ" be used to pigvait floating debris
froa accumulating near the pump suction;
In a multiple pond system, a herm of very coarse tailings can often
be used to filter out much of the floating debris;
In a single pond system, sediment removal froa the j-aii»-»o« and pre-
settling ponds is more crucial to successful, long-term operation.
Discharge froa properly functioning settling ponds should not be
routed through old, filled ponds where it might pick, up solids.
Figure 1-12. Settling/Recycle Pond
(Source: ADEC 1987)
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Mining Industry Profile: Gold Placers
Recreational and small-scale gold placer miners do not usually use settling ponds. Applying this
management technology to small operations results in disproportionately large in-stream or riparian
area disturbances. The use of settling ponds by small-scale gold placer miners also presents the risk
of increased erosion at the site. In sum, the reduction in sediment discharge must justify the
additional sediment likely to be produced by pond construction and stream diversion.
Flocculants
Flocculants could potentially be used as a final polishing step to reduce turbidity in a small volume of
effluent from a recycle system (ADEC 1987). Chemically assisted settling may involve the addition
of polymers to aid in the removal of suspended solids. For small gold placer mining operations, the
addition of chemicals to the settling pond increases beneficiation costs. The danger of chemical spills
and the potential for improper use of chemicals by recreational miners probably outweighs potential
improvements in settling.
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1.6 ENVIRONMENTAL EFFECTS
Most environmental effects associated with placer mining activities concern water quality.
Historically, the most severe impacts have been physical disturbances to stream channels and the
addition of large quantities of sediment downstream. As regulations governing placer mining evolved
to address these problems, environmental impacts became less severe, although, through the mid-
1980s, water quality impacts from placer mining continued to be documented. In 1988, effluent
limitations were placed on placer mines through the NPDES program (40 CFR 440 Subpart M).
Available data on environmental impacts of placers is often dated with the majority of information
collected prior to 1988. Annual reports from the ADEC, and one study conducted since the effluent
limitations were enacted, are discussed to provide a limited evaluation of the current status of
environmental impacts.
Prior to the initiation of any regulatory controls, placer mining operations, as previously mentioned,
created significant disturbances within stream channels. Little or no effort was made to recontour
waste rock piles to resemble the premining topography. Natural revegetation of mined areas from
Alaska to California ranges from none to complete. Depending on the remaining substrate, natural
stream patterns in some areas may take a century to return. These operations were also responsible
for generating large quantities of sediment and increasing concentrations of heavy metals, including
arsenic, copper, lead and mercury, downstream from mining activities (ADEC 1986; Clark 1970;
Holmes 1981).
This section does not purport to be a comprehensive examination of environmental effects that can
occur or that actually occur at mining operations. Rather, it is a brief overview of some of the
potential problems that can occur under certain conditions. The extent and magnitude of
contamination depend on highly variable site-specific factors that require a flexible approach to
mitigation. EPA is aware that many of the potential problems can be, and generally are, substantially
mitigated or avoided by proper engineering practices, environmental controls, and regulatory
requirements.
1.6.1 Surface Water
Surface water quality impacts are typically due to the addition or disturbance of sediments during
mining. Increases in turbidity levels, total suspended solids (TSS), some dissolved solids (primarily
heavy metals), and settleable solids (SS) are all concerns. Physical disturbances of stream channels
also effect wetlands and wildlife.
A study of mined and unmined streams conducted in Alaska during the 1985 field season showed that
total suspended solids were elevated in a number of actively mined streams. During this time period,
sediment ponds were employed at some operations and provided a wide range of effectiveness.
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Downstream uses; water supply, aquatic life, and recreation were precluded as a result of the
increased sediment loads in two of the three streams studied. Fine sediments were readily carried
downstream in response to increased stream flows (spring runoff); therefore the severity of localized
impacts could change with time as sediments were picked up and redeposited in different locations
downstream (ADEC 1986)
The same study found that total dissolved solids were not categorically increased as a result of mining
activities, although levels of iron, manganese, cadmium, mercury, copper and arsenic were elevated
below mining operations in some streams. (It is not clear from the study whether these concentrations
are expressed as total or dissolved). A study of water quality within the Circle District, Alaska,
conducted in 1983, showed elevated levels of total arsenic, copper, lead, and zinc, and elevated levels
of dissolved arsenic and zinc downstream from placer mining activity. Mercury and cadmium levels
were not elevated downstream from mining. Concentrations of dissolved constituents are typically of
more concern in terms of water quality as the dissolved fraction is available for uptake by living
organisms (ADEC 1986; LaPierriere et al. 1985).
The presence of metals in mined streams is dependant on the constituents of the pay streak and the pH
of the water. Arsenic behaves somewhat differently than other metals and, in actively mined streams,
is associated with settleable solids, those particles smaller than 75 microns (silt and clay). Studies
indicate that 84 to 88 percent of the arsenic attached to the suspended solids can be removed in
settling ponds given sufficient retention time. Dissolved forms and those attached to particles smaller
than 25 microns will not settle out and will be carried downstream in the mining effluent. There
were no discussions that presented possible controls for other heavy metals (ADEC 1986).
Turbidity is a measure of light transmission, measured in nephelometric turbidity units (NTU). Data
collected in 1985 showed turbidity ranging from 0.02 to 24 NTU upstream from mining activities;
downstream from mining, turbidity ranged from 19 to 6,600 NTU. The effects of the increase in
turbidity is addressed below as pan of the discussion of wildlife impacts (ADEC 1986).
The effectiveness of the 1988 regulations in reducing the severity of environmental impacts has yet to
be fully determined; however, the situation appears to be improving. The ADEC 1990 Annual
Mining Report states that the percentage of miners whose sampled wastewater contained 0.2 ml/1 or
less of settleable solids had drastically improved from 1984 through 1990 (ADEC 1991). During
1989 and 1990 however, most mines requested modifications of their turbidity requirements. The
regulatory requirement for turbidity was 5 NTU above the baseline level; modifications were granted
based on the dilution factor provided by the receiving stream, and averaged 587 NTU (ADEC 1991).
The 1991 ADEC Annual Mining Report states that 99 percent of the mines that had a discharge and
were sampled did not exceed the 0.2 ml/1 limit. The report also states that the trend in settleable
solids and turbidity data continue to improve (ADEC 1992). In 1991, a study of water quality
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associated with two mines in Alaska was conducted to evaluate the effect of reduced sediment
discharges. The study evaluated the concentrations of five metals upstream from mining and in
mining effluent at two locations in Alaska, one along the Fairbanks Creek and the other along
Porcupine Creek. Table 1-2 presents a summary of the turbidity and arsenic data.
Table 1-2. Turbidity and Arsenic Levels in Two Alaskan Creeks'
Location
Fairbanks Creek
Upstream location
Fairbanks Creek
Downstream location
Porcupine Creek
Upstream location
Porcupine Creek
Downstream location
Turbidity2
1.7 NTU
44NTU
0.76 NTU
51 NTU
Total Arsenic
30 ug/1
89 ug/1
1.8 ug/1
9. 1 ug/1
1 Data are mean values for water samples collected every six hours over a four day period during the
summer of 1991.
2 Turbidity is measured in nephelometric turbidity units (NTUs).
As indicated by the referenced data, turbidity increased at both sampling locations downstream of
mining. Neither creek exceeded the standards for cadmium, copper, lead or zinc (data not presented).
Concentrations of total arsenic levels were higher downstream than upstream concentrations. The
arsenic level at one mine was within the site-specific water quality limits'. The total arsenic
concentration below the second mine exceeded water quality standard values (sample mean 89 «g/L,
maximum 112 wg/L).
1.6.2 Ground Water
The information regarding placer mining effects on ground water is sparse. One water table study
conducted in Alaska found that impacts on stream hydraulics caused changes in the ground water flow
regime. The study also reports that in mined stream basins, specific conductance was higher and
dissolved oxygen concentrations were lower in aquifers than in the streams themselves. The
differences in dissolved oxygen and conductance were not significant between aquifers and streams in
unmined stream basins. The study concluded that sedimentation, as a result of mining, impacted the
water quality of alluvial aquifers within mined stream basins (Bjerklie and LaPierriere 1985).
'Alaska Water Quality Standards Workbook, ADEC, 1991.
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Additionally, the study suggested that increased fines deposition in stream basins may reduce
communication between surface water and alluvial ground water, thereby creating local zones of
depression in underlying aquifers.
1.6.3 Soil
By the very nature of most placer operations, soil is disturbed during mining. In many cases, topsoil
is removed and set aside for future use when reclaiming a site. Redirection of stream flow and use of
bulldozers and related equipment will impact soil stability and may cause greater soil erosion. Heavy
equipment may denude the soil surface and cause compaction of soil, and alter soil properties such as
porosity and infiltration. Loss of soil fines may decrease the water retention capacity of soils which
may in turn reduce populations of microorganisms in topsoil. The degree of soil disturbance will
vary from site to site and there are measures being used to minimize erosion and other impacts to
soil. In Alaska, frozen ground or permafrost may suffer greater long-term damage due to the
sensitivity of the environment. Specific data on soil disturbances were not available.
1.6.4 Wetlands
Mining activities, particularly those mining recent alluvial deposits are likely to impact wetlands
during the removal of vegetation and soils as well as the removal of the gravels that support wetland
hydrology. Reclamation of the hydrologic, soil and vegetation parameters that support wetlands is
currently an inexact science and the level of success in these efforts is yet to be determined on a
large-scale basis.
No discussions of placer mining impacts on wetlands were located, nor has information regarding the
acreage impacted by placer operations with U.S. Army Corps of Engineers Section 404 permits been
obtained. However, a discussion of Section 404 dredge permits is included in the regulatory section
of this report.
1.6.5 Wildlife
Wildlife is impacted by placer mining through the physical disturbance of stream channels, the
addition of sediments to the streams, and the presence of human activities and heavy equipment in
what are typically remote areas.
Aquatic and terrestrial wildlife may be impacted by the disturbance of stream beds and adjacent
alluvium by mining activities. Mining may present a physical barrier to fish migration through
disruption or diversion of the active channels. Analysis of data collected during the 1985 field season
found that the greater the length of disturbance within a mined stream channel, the lower the fish
density upstream. The riparian areas disturbed by mining activities are typically used by birds and
mammals for food, shelter and watering. Studies indicate that even on properly reclaimed areas.
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wildlife values are low for the first 10 to 15 years or until a relatively diverse riparian community can
develop (ADEC 1986).
High sediment concentrations and turbidity adversely impact fish and aquatic invertebrates. The
direct impacts from sediment on arctic grayling, the principal game fish within many Alaskan
streams, include gill damage, reduced fertility, and changes in blood chemistry. Reproduction is
inhibited when spawning grounds are lost to siltation and eggs are suffocated when covered by excess
sediment. Additionally, fry show decreased survival rates in waters with high levels of sediment
(ADEC 1986; Reynolds 1989).
Increases in turbidity levels do not cause direct effects on fish populations but can interfere with
visual activities such as feeding and spawning. Additionally, a study of primary productivity
(measured by dissolved oxygen and chlorophyll concentrations) showed a loss of productivity within
streams impacted by mining. In the most severely impacted streams, primary productivity dropped to
zero. The decreases in productivity, and the corresponding reduction in the food available at the
lowest level of the food chain, were directly related to increases in turbidity (Reynolds 1989; Van
Nieuwenhuyse and LaPierriere 1986).
Streams provide a general habitat for native fish populations. In addition, specialized stream habitats
may be needed by certain species for spawning and rearing. Mining tends to eliminate many of the
irregularities in a stream channel that provide variations in habitat such as bank and channel
vegetation, shade, pools, riffles and bed texture. Some impacts from mining that might not threaten
the life of individual fish may greatly affect the habitat needed by the species for successful spawning
and rearing of a new generation of fry. Furthermore, mining can disrupt the food chain by adversely
affecting the conditions necessary for the production of aquatic plants and invertebrates.
Although the impact to stream populations was not evaluated, Ray et al. in their 1992 study of two
Alaskan creeks noted changes in water temperature, pH, dissolved oxygen, and specific conductivity.
(Ray et al. 1992) Altering parameters such as these can impact aquatic ecosystems. Increases in
dissolved metals in soil or water may also adversely effect wildlife.
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1.7 MITIGATING MEASURES AND REMEDIATION
1.7.1 Tailings
The bare surfaces of tailings piles are often far above the summer water table and may have dry soils
during the summer Dry soils limit plant colonization and can cause tailings piles to stagnate in the
earliest stages of plant succession. Smoothed tailings piles created by current reclamation practices
are generally still too high above the summer water table for the establishment and growth of the
desired plant species. Thus, the rate of plant succession is not increased by smoothing operations.
Peat and topsoil respread onto tailings piles may actually retard plant succession by absorbing
rainwater and keeping the underlying sediments even drier than they would be without peat. This
hinders root penetration into the soil. Even grasses seeded onto reclamation areas can reduce soil
moisture and inhibit or delay the establishment and growth of native plants in northern Alaska
(Cooper and Beschta 1993).
One study found that for natural revegetation to be successful, the surface soil texture must contain at
least 10% fine sand, silt and/or clay. Also, the soil moisture level must be between slightly dry and
moist for natural revegetation to occur, in other words, the surface six inches must be moist, but not
saturated during at least part or all of the growing season. Finally, colonizing type plants must be
adjacent or very close on the up-wind side of the disturbed area to provide the seeds necessary for
natural revegetation (Davidson 1993).
1.7.2 Stream Channel
Placer mining of streams can severely alter the existing natural channel. Impacts include: removal of
large, instream substrate, including boulders and woody debris; clearing of riparian vegetation from
the floodplain; relocation (diversion) and straightening (reducing sinuosity and increasing gradient) of
the stream channel; and isolating side channels from the main channel (Blanchet and Wenger 1993).
Scannell (1993) states that a stream system can be considered to have three conditions: what it used to
be, which we may not even know; what it is now, which we can determine through sampling; and
what it can become. We can often predict what it can become and what uses it can support by the
type of stream channel, the flooding pattern of the stream, and even by how much money is available
for reclamation. In his study, Scannell stressed that we should not equate the attainable habitat with
what we perceive to be the undisturbed habitat. Instead, this study suggested that we define new
habitat goals for the stream channel and work to attain them. Although it may not be practical to
reclaim the hundreds of miles of disturbed stream habitat or to restore these streams to natural, or
pre-mined, conditions, we can consider these streams in terms of what beneficial uses they now
support and what attainable uses they might have (Scannell 1993).
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Streams channels provide native species of fish with habitats necessary for migration, spawning and
rearing In addition, stream quality influences the aquatic productivity of benthic invertebrates which
in turn provide food for larger fish. As a result, wildlife, and especially aquatic wildlife, can be
impacted by disruptions to any of the various habitats necessary for any of the stages in the life-cycle
of a species. However, in restoring a disturbed stream channel, care must be taken not to try and
force-fit a specific habitat to the existing topography of a site. Another study pointed out that stream
channel gradients must be allowed to vary in relation to the topography. In the long-term, variation
in channel planform, shape and gradient will provide a variety of fish habitat throughout the stream
such as pools, runs, riffles, and rapids (Latoski and Chilibeck 1993).
In remediating a mined portion of stream channel, Blanchet and Wenger (1993) identified several
restoration measures that can be employed to improve fish habitat such as:
• Replacing large stream substrate, including rocks and/or wood, to increase pool habitat and
cover in disturbed channel reaches
• Revegetating disturbed streambanks to increase nearshore cover and wood debris supply
• Developing side channel or slough access for fish fry in disturbed areas
• Accessing adjacent abandoned settling ponds and old channels to provide additional
offchannel rearing habitat.
This study went on to describe several methods for constructing instream structures to provide an
increase in habitat diversity. These structures include boulders and boulder clusters keyed into the
channel bottom; vortex rock weirs which are cross channel boulder structures V'ed slightly upstream
and with a spacing between individual boulders; log barbs consisting of wooden logs keyed into the
streambank between the high and low water levels and with the instream portion pointing upstream;
root wads installed and anchored into instream pools to provide additional cover within the pool; and
spruce tree revetments utilizing beetle-killed trees felled and attached along the stream bank using
earth anchors to provide diverse shelter and cover for fish fry even in relatively swift water (Blanchet
and Wenger 1993).
1.7.3 Floodplain
Floodplains provide a means by which streams can maintain a level of equilibrium with the stream
channel during times of flood. A natural floodplain provides room for a flooded stream to spread out
and slow down, thereby reducing the erosive force of the water. Vegetation on the floodplain further
helps to dissipate the energy of a flood-swollen stream and also helps to anchor the sediments to
prevent erosion. In fact, floodplains are often the site of sediment deposition. This deposition helps
to enrich the soils and make them more fertile.
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Placer mining can destroy a stream's natural floodplain, replacing a broad sinuous channel and
floodplain with a deep narrow channelized stream that concentrates all of its erosive power in a small
area of disturbed sediments. The inevitable result is increased erosion of the stream channel and
banks and increased turbidity of the down stream water.
Floodplains can be rebuilt following placer mining and stabilizing vegetation can be reestablished
either through reseeding or mature plantings. Individual site conditions may dictate the means for
rebuilding the floodplain. To protect against erosion, stream channels should be armored with the
coarsest material available. Gravels from piles left by mining can be used to fill in settling ponds, old
stream channels and other unnatural depressions. Excess gravels can be blended into the valley slope
along the floodplain's margin. Depending on the geometry of the valley and stream channel,
floodplains can be located on one or both sides of a stream. Typically floodplains are located on the
inside of bends or meanders and along both shies in straight reaches. Double terraces can be
constructed with the lower terrace designed to carry a 20 to 50 year flood, and the capacity of the
upper terrace designed to carry a 100 year flood (Karle 1993).
One of the problems to be considered when rebuilding a floodplain after mining has disturbed the
valley is the occurrence of a large flood before revegetation can occur. The choice between reseeding
and mature plantings may be based on the probability of a damaging flood occurring before seedlings
can become well enough established to withstand a flood. The probability of a flood occurring within
a given period of time can be calculated using the following equation from Karle (1993). The
probability J that a flood P will be equalled or exceeded in N years is:
J=1-(1-P)N
For example, in an estimated five year time period for revegetation to occur, there is a 67%
probability that a 5-year flood will occur or be exceeded, or a 41 % probability that a 10-year flood
will occur or be exceeded, and a 23% probability that a 20-year flood will occur or be exceeded
(Karle 1993).
To prevent erosion of the floodplain and to encourage sediment deposition from floodwaters, brush
can be planted in clumps or in linear plantings perpendicular to the stream channel. In addition.
small circular ridges made by the tracks of a bulldozer driving in a pattern of tight turns can be
effective in trapping precipitation runoff and small particles of sediment and airborne seeds as they
tumble across the roughened surface. These small ridges have also been shown to be effective m
trapping sediment when inundated by a flood (Karle 1993).
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1.7.4 Soils
Soils are more than a veneer of inorganic dirt or fine-grained mineral particles over bedrock. A true
soil is a combination of both mineral and organic (living and dead) material. Top soils are especially
rich in organic matter Plants require many nutrients provided by soils for proper health and growth.
In some cases, revegetation after placer mining may be as simple as stabilizing the site and allowing
natural revegetation to occur. In other cases, it may require replacing top soil and reseeding or
replanting.
According to Helm (1993), one aspect of plant establishment is the formation of mycorrhizae on the
plant roots. Mycorrhizae are symbioses between plants and fungi which are essential for growth of
most plant species under field conditions. The fungi help the plant absorb nutrients from the soil
while the plant provides energy for the fungi. However, microbial communities in the rooting zone
may be disrupted by natural or man-made disturbances such as glaciers, floods or placer mines.
In reestablishing vegetation on a mined site, mycorrhizal fungi propagules may. enter the rooting zone
of plants by natural dispersal or by their presence in topsoil or soil transfer treatments. Many placer
mines are long and narrow and have a good source of propagules next to the site. Topsoil that is
fresh or has not been stockpiled for too long may have viable fungi propagules present. If not, the
rooting zone of seedlings or cuttings can be treated (or inoculated) with viable soil from the rooting
zone of nearby plants. Different plant species can survive for varying lengths of time without
mycorrhizae and studies are still underway to fully understand the requirements of mycorrhizal
formation (Helm 1993).
1.7.5 Mined Land Remediation
To be truly successful, remediation of a mined area needs to be undertaken with a unified ecosystem
approach. Piecemeal attempts at solutions will generally not fully or successfully restore a section of
placer mined stream channel. The goal of a remediation program should include the restoration of
the stream channel, floodplain, and vegetation to recreate a valley bottom ecosystem similar to that
occurring in undisturbed streams (but not necessarily identical to the conditions existing in a given
stream prior to mining). This interaction will restore the ecological functions of these ecosystems.
Goals should also be to initiate natural plant succession processes on the streambanks, floodplain and
any non-floodplain portions of the mined area which will allow succession to operate at a rate similar
to that on natural floodplains.
Latoski and Chilibeck (1993) state that miners must be made aware that cost effective restoration
begins at the planning stage. Restoration requirements can then be integrated into the mining
operation with minimal cost to the miner (e.g., stockpiling organic material and boulders, separating
overburden and washed materials, etc.).
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In order to implement a successful remediation project, miners should start with a clear statement of
realistic goals or objectives. This should be more than just a simple recitation of the procedures to be
used in restoring the stream after mining has ceased; otherwise, the restoration project may become
an effon to apply a specific technique regardless of results rather than achieve a specific condition in
the stream With clear objectives identified beforehand, proper site-specific measures can be
employed so that effective stream remediation is much more easily achieved.
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1.8 CURRENT REGULATORY AND STATUTORY FRAMEWORK
Gold placer mining activities must meet the requirements of both Federal and state regulations.
Environmental statutes administered by EPA or the states, such as the Clean Water Act (CWA), apply
to mining sites regardless of the status of the land on which they are located. The extent to which
other Federal regulations apply depends on whether a mining operation is located on federally owned
land. Federal regulations exist for operations on lands managed by the U.S. Bureau of Land
Management (BLM), the U.S. Forest Service (FS). the U.S. Fish and Wildlife Service (FWS), the
National Park Service (NPS), and other management agencies. In addition, the U.S. Army Corps of
Engineers has promulgated rules for construction and mining activities that have the potential to
impact wetlands and navigable waters. Finally, operations must comply with a variety of state
requirements, some of which may be more stringent that Federal requirements.
This section summarizes the existing Federal regulations that may apply to gold placer operations. It
also provides an overview of the operational permitting and water quality and on quality regulations
in two gold placer states, Alaska and Colorado.
1.8.1 Environmental Protection Agency Regulations
1.8.1.1 Resource Conservation and Recovery Act
The EPA implements the Resource Conservation and Recovery Act (RCRA) to protect human health
and the environment from problems associated with solid and hazardous wastes. Mining wastes are
included in the Act's definition of solid waste and in 1978, when EPA proposed regulations for the
Subtitle C hazardous waste program, special management standards were proposed for mining wastes.
However, in 1980, RCRA was amended to include what is known as the Bevill Amendment
(§3001(b)(3)(A)). The Bevill Amendment provided a conditional exclusion from RCRA Subtitle C
hazardous waste requirements for wastes from the extraction, beneficiation, and processing of ores
and minerals.
The exemption was conditioned upon EPA's preparation of a report to Congress on the wastes and a
subsequent regulatory determination as to whether regulation under Subtitle C was warranted. EPA
met its statutory obligation with regard to extraction and beneficiation wastes with the 1985 Report to
Congress: Wastes from the Extraction and Beneficiation of Metallic Ores, Phosphate Rock, Asbestos,
Overburden from Uranium Mining, and Oil Shale. In the subsequent regulatory determination (51 FR
24496; July 3, 1986), EPA indicated that extraction and beneficiation wastes (including gold mining
and milling wastes) should not be regulated as hazardous but should be regulated under a Subtitle D
program specific to mining waste.
EPA subsequently studied processing (i.e., smelting and refining) wastes and in 1990 submitted its
Report to Congress on Special Wastes From Mineral Processing. This report covered 20 specific
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mineral processing wastes; none involved gold processing wastes. In June 1991, EPA issued a
regulatory determination (56 FR 27300) stating that regulation of these 20 mineral processing wastes
as hazardous wastes under RCRA Subtitle C is inappropriate or mfeasible. Any mineral processing
wastes not specifically included in this list of 20 wastes no longer qualifies for the exclusion (54 FR
36592)
As discussed above, wastes from the extraction and beneficiation of minerals (including gold placer
operations) are generally excluded from RCRA Subtitle C requirements by the Bevill Amendment and
EPA's subsequent regulatory determination. EPA interprets this exclusion to encompass only those
wastes uniquely associated with extraction and beneficiation activities: the exclusion does not apply to
wastes that may be generated at a facility but are not uniquely related to extraction or beneficiation.
For example, waste solvents that meet the listing requirements as a hazardous waste under 40 CFR
Section 261.31 and are generated at an extraction or beneficiation facility by cleaning metal parts
(eg., activities not uniquely related to extraction or beneficiation) are considered listed hazardous
wastes and regulated as such. These wastes must be managed as any other hazardous waste, subject
to the Federal requirements in 40 CFR Parts 260 through 271 (or State requirements if the State is
authorized to implement the RCRA Subtitle C program), including those for manifesting and disposal
in a permitted facility.
1.8.1.2 Clean Water Act
Under Section 402 of CWA (33 USC §1301, et seq.), all point source discharges to waters of the
United States from industrial and municipal sources must be permitted under the National Pollutant
Discharge Elimination System (NPDES). A point source is defined as any discreet conveyance.
natural or manmade, which includes pipes, ditches, and channels. NPDES permits are issued by EPA
or delegated states.
Under Sections 301 and 302, NPDES permittees must meet specified effluent limitations established
under the CWA. Effluent limitations may be either technology-based or water-quality-based. With
respect to technology-based limitations, there are separate limitations applicable to existing sources of
discharges. They include, but are not limited to, best practicable technology (BPT) and best available
technology economically achievable (BAT). Also, under the New Source Performance Standards
(NSPS), new sources must use the best available demonstrated technology (BADT).
Technology-based limitations specifically applicable to the gold placer mine subcategory of the Ore
Mining and Dressing Point-Source Category are codified in 40 CFR 440 Subpart M. These standards
are only applicable to large placer mining operations (defined as mines which beneficiate more than
1,500 cubic yards of ore per year or dredges handling more than 50,000 cubic yard of ore per year)
There are no regulations under the CWA specific to small placer mine operations.
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The effluent limitation guidelines contain a storm exemption for a treatment systems designed,
constructed, and maintained to contain the maximum volume of flow which would result from four
hours of beneficiation plus a five-year, six-hour rainfall. Such facilities must meet best management
practice (BMP) standards, as well. BMP standards require that NPDES permits include, to the
greatest extent possible, provisions addressing such things as surface water diversions, berm
construction, and pollutant materials storage (U S. EPA 1988).
In addition to such technology-based limitations, an NPDES permit may contain water-quality-based
limitations. The CWA requires EPA to ensure that discharges of pollutants from a point source into
waters of the United States will not interfere with the water quality. States are required to develop
water quality standards to protect the designated uses of the receiving water. Where technology-based
standards are inadequate to provide such water quality protection, water quality-based effluent
limitations must be developed. Permit writers must determine that the technology-based standards are
sufficient to ensure that such standards are being met.
Some discharges from mine sites do not meet the definition of point source discharge because they are
not controlled through a discrete conveyance. These types of discharges are frequently considered
nonpoint source discharges. Under Section 319 of the CWA, states are required to prepare nonpoint-
source assessment reports and to develop programs to address such discharges.
Under Section 402, EPA promulgated regulations in 1990 requiring NPDES permit applications for
point source storm water discharges from industrial facilities, including active and inactive/abandoned
mine sites contaminated by contact with overburden, raw material, etc.. These facilities were
required to submit permit applications by October 1, 1992 (U.S. EPA 1990b). Under EPA's strategy
to implement permitting for industrial sources of storm water, EPA and some delegated States have
issued general permits which cover mining sites. Some mining sites will be addressed with individual
permits. However, these general permits do not address inactive mines on Federal lands; for these,
EPA is developing a separate set of general permits.
In recent years in Alaska, the State Water Quality Standards for turbidity (normally 5 NTU above
background) and total arsenic (0.05 mg/L) have been incorporated into NPDES permits. The
turbidity limit may be modified depending upon the amount of dilution provided by the receiving
stream. In 1989 and 1990, for example, there were 363 and 64 applications, respectively, for
NPDES placer mining permits. From the 1989 applications, 338 (93%) received modified turbidity
limitations allowing greater than 5 NTU; in 1990, 60 (94%) received similar modifications. (ADEC
1990.)
1.8.1.3 Dredged and Fill Material
Under Section 404 of the CWA, the U.S. Army Corps of Engineers (COE) is authorized to issue
permits for the discharge of dredged or fill materials, including that from gold placer mining
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operations, into navigable waters at specified disposal sites (Permit form 4345). Such permits may
only be issued after notice and the opportunity for public hearings has been provided. A State may
administer us own permit program governing the discharge of dredged and fill materials into
navigable waters by submitting to EPA a detailed description of the proposed program (and generally
obtaining approval of such program) in accordance with the CWA.
Also under Section 404, EPA is authorized to prohibit the specification (i.e., use) of a defined area
(or restrict the use of such an area) as a disposal site whenever EPA determines that, after notice and
the opportunity for a hearing, discharge of such materials will have an unacceptable adverse effect on
municipal water supplies, shellfish beds, fishery areas, wildlife, or recreational areas (in making this
determination EPA must consult with the COE). The CWA requires that in specifying a particular
disposal site in a 404 permit, the COE must apply guidelines developed by the EPA, in conjunction
with COE. These guidelines are found at 40 CFR 230. The guidelines are intended to restore and
maintain the chemical, physical, and biological integrity of waters of the United States.
Section 404 authority has been construed to extend to all waters of the United States, not just
navigable waters (33 CFR 328.1). Waters of the United States have been construed to include
"wetlands." Therefore, the COE issues permits for discharges to wetlands, as well as other waters of
the United States. Gold mining operations (including placer operations) have a significant potential to
physically restructure wetlands (U.S. EPA 1992a).
EPA and the COE use the same definition of wetlands (the U.S. Fish and Wildlife Service uses
another definition). The definition is:
The term "wetlands" means those areas that are inundated or saturated by surface or
ground water at a frequency and duration sufficient to support, and that under normal
circumstances do support, a prevalence of vegetation typically adapted for life in
saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and
similar areas (33 CFR 323.2(c)).
The issuance of a permit by COE may be subject to the requirements of the National Environmental
Policy Act (NEPA), as such issuance is deemed a major Federal action significantly affecting the
quality of the human environment (Section 511[c]).
The COE (or a State to which permit program authority has been delegated) may issue individual or
general (i.e., Statewide, nationwide, regional) permits. The COE (or an authorized State) may issue
a general permit, after notice and an opportunity for public hearing, for any category of activities
involving discharges of dredged or fill materials where the COE (or the State) finds that the activities
in such category are similar in nature and will cause only minimal adverse environmental effects when
considered individually and cumulatively. General permits are widely used to speed up the Section
404 permitting-process, because they do not require detailed, case-specific review. Such permits are
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issued to the public at large and authorize specified activities in wetlands and other waters (U.S. EPA
1992b).
Until 1986. all discharges into waters of the United States from mining operations, including placer
mining, were regulated by the COE under Section 404 as discharges of dredged materials. However.
in this same year, EPA and the COE entered into an agreement (updated in 1990) which clarified the
jurisdiction of the two agencies with respect to placer mining-related discharges. The agreement
established that point source discharges from placer mining operations would be subject to NPDES
permitting by EPA under Section 402, but that some discharges of materials incidental to such
operations may still be considered dredged or fill materials, subject to Section 404 permitting by COE
(U.S. EPA 1991). Such materials subject to COE permitting include material used in sediment pond
construction and the filling of dredge pits. Materials from gold placer mining operations are subject
to NPDES permitting as a waste discharge (U.S. EPA 1992a).
In Alaska (see following discussion of State permits), the State issues a Certificate of Reasonable
Assurance that proposed discharges to waters in the State will be in compliance with the Alaska Water
Quality Standards and the Alaska Coastal Management Plan (Department of Environmental
Conservation, 1990).
Alaska recommends that if it is likely that a mining activity will affect a "wetland" (which includes all
saturated soils and permafrost) a Section 404 permit application should be filed. The COE will
decide whether or not the operation is likely to have an effect on a wetland. Such a decision (a
"jurisdictional determination") may be based upon a field inspection of the site or on maps of Alaska
(Alaska, DNR, Division of Mining, undated).
1.8.2 Department of the Interior
1.8.2.1 Bureau of Land Management
Gold placer operations on Federal land are subject to Bureau of Land Management (BLM)
regulations. All mining claims located on lands managed by the BLM are subject to BLM regulation
to prevent "unnecessary and undue degradation" of the Federal lands and resources involved. The
BLM's authority to regulate mining claim operations under this "unnecessary and undue degradation"
standard derives from the Federal Land Policy and Management Act of 1976 (FLPMA), the statute
which sets out the BLM's general land management and planning authority. Exploration sites are
subject to the less-than-5-acre exemption or must submit a plan of operation if greater than 5 acres.
BLM does not have a program geared specifically towards placer mining; placer operations are
handled in the same manner as other mining operations with the same permitting, reclamation and
bonding requirements. (BLM 1993a, 1993b.)
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The BLM's general surface management regulations governing mining claim operations, which
include gold mining operations, are found at 43 CFR Part 3809. These regulations cover general
design, operating and reclamation standards, monitoring requirements, bonding requirements,
environmental review requirements, and remedies for noncompliance. They establish three general
use categories for mining operations, each eliciting different levels of oversight by the BLM. These
categories are (1) casual use operations (i.e., those that normally result in only negligible disturbances
of Federal lands and resources and that require no prior notice to or approval from the BLM), (2)
notice-level operations (i.e., those that involve disturbances of 5 acres or less for which the operator
must notify the BLM prior to commencing surface disturbing activities), and (3) plan-level operations
(i e.. disturbances of greater than 5 acres, and operations in some specified areas, for which the
operator must obtain BLM approval of a plan of operations prior to commencing activity).
All operations, including casual use and operations under either a notice or a plan of operations, must
be conducted to prevent unnecessary or undue degradation of the Federal lands. All operations must
also be reclaimed and must comply with all applicable State and Federal laws, including air and water
quality standards such as those established under the CAA and the CWA.
All plan-level operations, regardless of operation type (e.g., strip, open-pit, dredge, and placer) will
be required to post a bond. Bond amounts are to be set at the discretion of the BLM (up to $2,000
per acre), depending on the nature of the operation, the record of compliance, and whether it is
covered by a satisfactory State bond.
Mining claims located in BLM wilderness study areas are generally subject to stricter regulation than
other mining claims. The regulations covering mining in wilderness study areas are found at 43 CFR
Part 3802.
The BLM has the authority to issue leases for gold on certain acquired (as opposed to public domain)
lands. Although this is rarely done, such leases would be covered by the general regulations
applicable to hardrock leasing found at 43 CFR Part 3500.
The National Environmental Policy Act (NEPA) of 1969 requires Federal agencies to consider the
environmental impact of proposed activities. BLM uses the NEPA process to review proposed
mining operations. A site may require an Environmental Assessment (EA) or an Environmental
Impact Statement (EIS).
1.8.2.2 National Park Service and Fish and Wildlife Service
Location of new mining claims is generally prohibited in most areas managed by the National Park
Service (NPS) and the Fish and Wildlife Service (FWS). Neither the NPS nor the FWS have a
specific program for gold placer operations. Regulations at 36 CFR Part 9 govern activities on land
managed by the NPS under patented and unpatented mining claims in existence prior to inclusion of
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the land under the NFS. The NFS regulations restrict water use, limit access, and require permits
and complete reclamation.
The regulations of 50 CFR Part 29 govern mining activities under mineral rights on lands managed
by the FWS. The FWS regulations are fairly general and require that operations prevent, to the
greatest extent possible, the damage, erosion, pollution, or contamination of the area. Leasing on
FWS land is allowed only when operations are not incompatible with the aims of the refuge or other
FWS center.
1.8.3 Department of Agriculture (Forest Service)
Forest Service regulations are similar to BLM regulations and provide for consultation with
appropriate agencies of the U.S. DOI to review technical aspects of proposed plans of operation.
Unlike BLM, the Forest Service regulations do not specify acreage limitations. Although the BLM
has general management authority for the mineral resources on Forest Service lands, the BLM
regulations governing activities under mining claims do not apply to units of the Forest Service.
Instead, surface uses associated with operations under mining claims on Forest Service lands are
governed by regulations in 36 CFR Part 228, Subpart A. The general regulations apply to placer
operations, however; there are no special provisions for these operations.
The Forest Service requires a notice of intent to operate; this notice is filed with the district ranger.
If the district ranger determines that the operations will be likely to cause significant disturbance of
surface resources, the operator must submit a proposed plan of operations. Neither a notice of intent
nor a proposed plan of operation are required for the locating or marking of mining claims, mineral
prospecting that will not cause significant surface disturbance, operations that do not involve
mechanized equipment or the cutting of trees, or uses that will be confined to existing roads.
Like the BLM, the Forest Service may require an environmental assessment or environmental impact
statement according to the National Environmental Policy Act (NEPA) program. Bonds are required
to cover the cost of reclamation. Regulations specific to mining operations in Wilderness Areas are
addressed in 36 CFR Part 293.
1.8.4 State Programs
1.8.4.1 Alaska
Exploration, claim staking, permitting, mining, and reclamation in Alaska is regulated by several
State agencies. (Federal agencies also issue permits for activities in Alaska; see above). Among the
State regulatory agencies with regulatory authority applicable to gold placer mining operations are
the Department of Natural Resources' Division of Mining; the Alaska Department of Environmental
Conservation; and the Alaska Department of Fish and Game. State permitting authorities are
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discussed below Also included is an overview of Alaska's reclamation and bonding regulations, as
they apply to gold placer mining operations
The Annual Placer Mining Application
The Annual Placer Mining Application (APMA) form must be completed and submitted to the
Division of Mining (DoM) for all mining activities except for lode or hardrock mining. The APMA
form is not itself a permit, but rather an application which may serve as the basis for the issuance of a
number of required permits in Alaska. If this form is submitted along with a $100 application fee,
the completed form is sent by DoM to numerous Alaska (and Federal) agencies, such as the Alaska
Department of Fish and Game (see discussion of "Title 16 permits" below) and may, at the discretion
of receiving agencies, serve as the basis for issuance of their respective permits. Federal agencies
which receive copies of the APMA include the Federal land managers (Forest Service or Bureau of
Land Management) (if the site is on Federal lands) and the National Park Service (if the site is on
land under its control).
The APMA saves time for miners in that they may not have to complete individual permit
applications for each permit required in the State. However, the APMA will not suffice as the
application for a NPDES or Section 404 permit, as specific permit application forms are required for
such permits. Also, since acceptance of the form for the issuance of a particular permit (e.g.,
National Park Service permit) is discretionary, the particular agency receiving the permit application
form may request that additional or supplemental information accompany the APMA form.
The APMA form includes a reclamation plan form and a Statewide bond pool form (see following
discussion on reclamation and bonding regulations). The bonding pool was established in Alaska for
operations over five acres and which are on State land and for all unreclaimed areas on Bureau of
Land Management operations. The total cost to join the pool is $150 per acre.
The application requests information concerning the intended placer mining method (e.g., suction
dredge, bucket line dredge), make-up water supply, recycling/settling pond system (e.g., length and
depth), overburden, access, and exploration trenching and drilling. Also, the form contains a Coastal
Zone Management (CZM) Certification Statement (Certification Statement) that must be completed by
applicant's whose proposed operation is located in the Coastal Zone. The Certification Statement is
intended to satisfy the requirements of the Federal Coastal Zone Management Act, which requires,
among other things, that applicants for permits to conduct activities affecting land or water use in
Alaska's coastal area provide certification that the activities will comply with the standards of the
Alaska Coastal Management Program (State of Alaska, Department of Natural Resources', Division of
Mining 1992).
Title 16 Permit
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This permit is issued by the Alaska Department of Fish and Game under Alaska law. Its purpose is
to protect Alaska's anadromous fish, especially salmon. The mining activity must not interfere with
the safety of the fish. Also, the Department's permitting authority extends to the establishment of a
"fishway." which means basically that mine sites must provide adequate passage for the fish. Title 16
permits require the best management practices be applied to ensure that normal flow of creek is
segregated from active mining area.
Dam Safety
The Alaska Department of Natural Resources, Division of Water issues permits to ensure dam safety.
Plans for dam construction must be reviewed and approved by the Division prior to construction, and
monitoring is conducted during construction to ensure compliance with the approved plans. The State
has three categories of dams based on hazard risks: high, significant and low risk. The categories are
essentially similar to that used by the Army COE. Dams that are categorized as high or significant
risk require inspections at a minimum of once every three years. Low risk dams require inspections
at least once every five years. Inspections are the responsibility of the dam operator, although the
State reviews and approves qualifications of the individuals or firms selected to perform the
inspections. (Alaska DNR 1993.)
According to the laws and regulations of the State, a permit is required to close or abandon a dam.
The applicable State statute is the Alaska Dam Safety Act (1987); Dam Safety Regulations (1989) are
contained in 11.A8293 Article 3. (Alaska DNR 1993.)
Other State Permits
Other permits are required by the State for activities related to gold placer mine operations, but are
outside the scope of this examination. One such permit concerns water access rights of miners.
Generally, a permit to allow miners' access to waters for mining operations is required from the
DNR's Division of Land and Water.
Reclamation and Bonding
Under Alaska Statute 27.19, Alaska requires reclamation plans and bonding for all material mining
operations on State, Federal, municipal, and private lands, where such operations involve a mined
area of five acres or more. (The APMA, discussed previously, includes forms to address these
requirements). Also, BLM requires reclamation bonding of all operations on Federal lands regardless
of size.
The regulations promulgated pursuant to Statute 27.19 contain reclamation performance standards
which require that miners reclaim areas disturbed by mining operations so that any surface that will
not have a stream flowing over it is left in stable condition. "Stable condition" is one which allows
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for " the reestablishment of renewable resources on the site within a reasonable period of time by
natural processes" and which can be expected to return waterborne soil erosion to pre-mining levels
within one vear after the reclamation is completed and can achieve revegetation.
Reclamation regulations also address bonding requirements and reclamation plan submittal and
approval At least 45 days before commencement of mining activities, a miner must submit a
proposed reclamation plan to the State for approval. Within 30 days of determining that the plan is
complete, the State must approve, disapprove, or conditionally approve the plan. The plan does not
take effect until the miner satisfies the bonding requirements.
Plans submitted on forms other than the one provided by the State (i.e., APMA) must include
information such as:
• list of all properties, mining locations, and leases on which the mining operations are to be
conducted;
• a map showing the vicinity of the operation;
• general description and diagram of the operation and mined area, including acreage to be
mined in each year covered by the plan;
• estimated number of yards or tons of overburden or waste and ore/materials to be mined
each year; and
• a description of the reclamation measures to be taken, including a time schedule.
In addition to plan submittal (and approval), all miners except for exempt miners (discussed below),
must comply with bonding provisions. Bonding requirements allow for any number of options to
satisfy the financial assurance provisions. Some of the options include:
• participating in a statewide bonding pool (which basically allows a miner to pay into a pool
each year 15% of the miner's total bond amount for the year, plus an annual fee of five
percent the total bond amount [this usually results in a bonding pool deposit of $112.50
per acre and a fee of $37.50 per acre]);
• posting a performance bond [either a corporate surety bond or a personal bond
accompanied by a letter of credit, certificate of deposit, or cash or gold deposit]; or
• posting a general performance bond assuring that reclamation standards are met and which
is for no less than $750 per acre of mined area (11 AAC 97 1992).
Operations smaller than five acres are exempt from bonding requirements, as well as the requirement
to submit a reclamation plan. However, such exempt miners must file, annually, a "letter of intent"
prior to commencement of mining activities. The letter must include most of the information required
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for non-exempt mining operation required in reclamation plans, but non-exempt miners do not have to
obtain approval of the data in the letter. The data required in the letter of intent includes the
following: a list of properties and mining location or leases on which operations will be conducted; a
map of the general vicinity of the mining operation; and total acreage to be reclaimed in the year
covered by the letter of intent.
1.842 Colorado
The primary State mining law is the 1976 Colorado Mined Land Reclamation Act (MLRA) (34-32-
101 et seq. C.R.S.), which succeeded the Colorado Open Land Mining Act of 1973. (ELI 1992)
Colorado has a number of placer mines, although the number in actual operation at any one time
varies. Almost all of the placer mines in Colorado operate on an intermittent basis, fluctuating
seasonally or with market prices. Colorado does not have specific regulations for placer mining;
placer mines in the state must adhere to the same regulations as other mines. Colorado regulations
are fairly generic for all mining operations; specific requirements are written into each individual
permit (Colorado DNR 1993).
The Colorado Department of Natural Resources, Division of Minerals and Geology administers the
MLRA, while the Mined Land Reclamation Board issues rules and regulations, reviews permits, and
oversees enforcement. Nonpoint source and ground water discharges at mining operations also are
under the jurisdiction of the Division of Minerals and Geology.
Although Colorado does not have specific guidance or policy for placer operations, some of the
applicable mining program elements are highlighted below.
Mining and Reclamation
All placer operations must have a permit if they mine and sell gold. Regular operating permits are
required for mining operations affecting ten acres or more, or extracting 70,000 tons/annually
(mineral and/or overburden). The State issues limited impact operation permits to facilities less than
ten acres in size. A further distinction is made for those operations that are less than ten acres and
are located in or adjacent to stream channels, or on certain Federal or State recreational or wilderness
lands. Approximately 50 percent of the State's placer operations are less than ten acres in size.
Special applications for two acre limited impact facilities are processed on an expedited basis and
require financial assurance bonds of only $1500 (ELI 1992; Colorado DNR 1993). New mines
require reclamation permits under the MLRA prior to beginning operations.
A notification of temporary cessation is required if a facility will cease operations for more than 180
days. The facility must ensure that the facility is stabilized prior to cessation, and the Division of
Minerals and Geology may conduct inspections to verify facility compliance with this. The Mined
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Land Reclamation Board typically reviews the temporary cessation notice (Colorado DNR 1993).
Because most placer operations in the State are intermittent, the temporary cessation policy is
particularly important to placer mining operations. A five year period is allowed for temporary
cessation, after an inactive period of five years, a facility must begin reclamation. A facility may
apply tor a second five year period of inactivity, although the Mined Land Reclamation Board will
conduct a thorough review of the facility plans prior to authorization.
All permits issued by the Mined Land Reclamation Board require financial assurances, including
placer operations. The dollar amount of financial assurances varies depending on the type and extent
of operation, and the estimated reclamation costs. Financial assurances are required throughout the
life of the permit until reclamation has concluded. Concurrent reclamation of placer operations is
encouraged by the State through bond mechanisms. Bonds are typically lower for facilities
conducting concurrent reclamation. Usually a disturbed acreage limitation is listed in a facility's
reclamation permit, no more than two acres can be disturbed at any one time for example, and prior
to excavating a new area the old area must be reclaimed (Colorado DNR 1993).
Counties with zoning requirements may issue, through the zoning committees, a certificate of
designation, which is akin to a land-use permit. The level of involvement of Counties in issuing
mining permits is quite variable throughout the State. Sites on public lands may be jointly reviewed
by the State and BLM or Forest Service.
Surface Water Discharges
Water quality and releases related to mining are regulated by the Colorado Department of Health,
Water Quality Control Division and the Water Quality Control Commission under the State's Water
Quality Control Act. Water quality standards are set by the Division, and permits are issued for
discharges to surface water through NPDES/Colorado Discharge Permit System (CDPS) permits.
Colorado has a federally-approved NPDES program. The Permits and Enforcement Section,
Industrial Unit, of the Water Quality Division issues CDPS permits, which are required for all active
mines that have a point source discharge to surface water.
There is a CDPS general permit for placer mining. The general permit covers water used to transport
alluvial material through a separator, runoff crossing the disturbed area, surface and ground water
associated with placer mining activities, and other process water as determined by the Water Quality
Control Division (ELI 1992). There is a CDPS general permit for Stormwater Discharges Associated
with Metal Mining Operations, Permit No. COR-040000, issued September 14, 1992, and valid
through September 30, 1996 (Colorado DOH 1992). Site specific dredge permits (per Section 404 of
CWA) may also be required at some placer sites.
Colorado has a Passive Treatment of Mine Drainage (PTMD) program for controlling drainage that is
not subject to NPDES/CDPS requirements. The PTMD program approves construction, operation.
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and sets standards for systems used to control mine drainage. The program covers biological,
geochemical and physical drainage control or treatment measures such as cascades, settling ponds, and
man-made wetlands (standard reclamation measures are not included under PTMD). (ELI 1992.)
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1.9 REFERENCES
Alaska Department of Environmental Conservation. 1986. A Water Use Assessment of Selected
Alaska Stream Basins Affected fry Gold Placer Mining. Prepared by Dames & Moore, Arctic
Hydrologic Consultants. Stephen R. Braund and Associates, L.A. Peterson and Associates, and
Hellemhal and Associates.
Alaska Department of Environmental Conservation. 1987 (March). Placer Mining Demonstration
Grant Project Design Handbook (prepared by L.A. Peterson & Associates, Inc.). Fairbanks,
AK.
Alaska Department of Environmental Conservation. 1988 (June 3). Placer Mine Inspection Form,
with an EPA NPDES Compliance Inspection Report cover sheet dated August 2, 1988 and
signed by Conrad Christiansen.
Alaska Department of Environmental Conservation. 1989 (December 19). Decision Record, with
attachments.
Alaska Department of Environmental Conservation. 1990. 7990 Annual Mining Report. Alaska
Department of Environmental Conservation, Division of Environmental Quality. Fairbanks,
Alaska.
Alaska Division of Mining. 1992 (May 6). Alaska Division of Mining Approved Reclamation Plan.
Approved by John E. Wood.
Alaska Department of Natural Resources. 1992a (February 21). Alaska Department of Natural
Resources Case File Abstract.
Alaska Department of Natural Resources, Division of Geological and Physical Surveys. 1992b
(February). Alaska's Mineral Industry 1991 Survey (by T.K. Bundtzen, R.C. Swainbank, J.E.
Wood, and Albert Clough). Information Circular 35. Fairbanks, AK.
Alaska Department of Natural Resources. 1992c (April 27). Alaska Department of Natural
Resources, State Wide Bond Pool Form.
Alaska Department of Natural Resources, Division of Mining. 1992d. Annual Placer Mining
Application, with attachments.
Alaska Department of Natural Resources, Division of Water. 1993. Kyle Cherry, personal
communication with Michelle Stowers, Science Applications International Corporation, Falls
Church, Virginia, on June 15, 1993.
Alaska Department of Natural Resources, Division of Mining. Undated. Letter to potential
miners/prospectors on permits required for mining, reclamation, or mineral exploration in
Alaska.
Alaska Miners Association. 1986. Placer Mining - A Systems Approach. Short Course, Alaska
Miners Association Eleventh Annual Convention, October 29-30, 1986. Anchorage, Alaska.
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Argall, G.O . Jr. 1987 (December). "The New California Gold Rush." Engineering & Mining
Journal- 30-37.
Bauihndge. K L 1979 Evaluation of Wastewater Treatment Practices Employed at Alaskan Gold
Pltuer Mining Operations, Calspan Corporation Report No. 6332-M-2.
Bjerklie. D M and J D. LaPierriere. 1985 (April). Gold-Mining Effects on Stream Hydrology and
Water Quality, Circle Quadrangle, Alaska. Water Resources Bulletin: 235-242.
Blanchet, D and Wenger, M. 1993. Fisheries Habitat Restoration in Placer Mined Reaches of
Resurrection Creek, in Papers of the Second EPA Placer Mine Reclamation Workshop. U.S.
EPA publication If EPA 910-R-93-015.
Boyle, R. W. 1979. The Geochemistry of Gold and Its Deposits. Canada Geological Survey Bulletin
280. Canadian Publishing Centre. Hull, Quebec, Canada. 584 pp.
Clark, W B. 1970. Gold Districts of California. California Division of Mines and Geology,
Bulletin 193. San Francisco, CA.
Code of Federal Regulations. Section 40, Part 440, Subpart M - Gold Placer Subcategory. 1989.
Office of the Federal Register, National Archives and Records Administration. Washington,
DC.
Colorado Department of Health, Water Quality Control Division. 1992 (September). CDPS General
Permit, Stormwater Discharges Associated with Metal Mining Operations, Authorization to
Discharge Under the Colorado Discharge Permit System, Permit No. COR-040000, Issued
September 14, 1992.
Colorado Department of Natural Resources, Division of Geology and Minerals, 1993. Bill York-
Fern, personal communication with Michelle Stowers, Science Application International
Corporation, Falls Church, Virginia, June 9, 1993.
Cooper, D.J. and Beschta, R.L. 1993. Restoration of a Placer Mined Valley Bottom in Interior
Alaska: Birch Creek at Steese Highway Mile 99. In Papers of the Second EPA Placer Mine
Reclamation Workshop. U.S. EPA publication # EPA 910-R-93-015.
Cope, L.W., and Rice, L.R. (editors). 1992. Practical Placer Mining. Society for Mining,
Metallurgy, and Exploration, Inc. Littleton, CO.
Davidson, D.F. 1993. A Preliminary Inventory of Abandoned Mine Sites on the Chugach Nation
Forest and the Present State of the Natural Vegetation. In Papers of the Second EPA Placer
Mine Reclamation Workshop. U.S. EPA publication # EPA 910-R-93-015.
Environmental Law Institute. 1992 (November). State Regulation of Mining Waste: Current State of
the Art, prepared under Grant Agreement No. X-818255-01-0, funded by the U.S.
Environmental Protection Agency.
Ferguson, J.F. and Gavis, J. 1972. "A Review of the Arsenic Cycle in Natural Waters." Water
Research: 6:1259-1274.
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Flatt. P. 1990 (March). "Fine Placer Gold Recovery Methods." California Mining Journal: 5-8.
Gomes, J M. and Martinez, G.M. 1983. Recovery of Gold and Other Heavy Minerals From
Alluvial Deposits: Equipment and Practices. In The Encyclopedia of Placer Mining (R.A.
Hatkoff, ed.) Inter Resources Publications, Lakewood, Colorado.
Many, D M and Terlecky, P.M. 1980. Titanium Sand Dredging Wastewater Treatment Practices,
Frontier Technical Associates, Inc. Report No. 1804-1 for the U.S. Environmental Protection
Agency, Effluent Guidelines Division.
Many, D.M. and Terlecky, P.M. 1984a (February). "Existing Wastewater Recycle Practices at
Alaskan Placer Gold Mines", Frontier Technical Associates, Memorandum to B.M. Jarrett, U S.
EPA, Effluent Guidelines Division.
Harty, D.M. and Terlecky, P.M. 1984b (February). "Water Use Rates at Alaskan Placer Gold
Mines Using Classification Methods", Frontier Technical Associates, Memorandum to B.M.
Jarrett, U.S. EPA, Effluent Guidelines Division.
Harty, D.M. and Terlecky, P.M. 1984c. "Reconnaissance Sampling and Settling Column Test
Results at Alaskan Placer Gold Mines", Frontier Technical Associates Report No. FTA-84-
1402/1, prepared for U.S. EPA, Effluent Guidelines Division.
Hatkoff, R.A. 1983. The Encyclopedia of Placer Mining. Inter Resources Ltd. Denver, CO.
Helm, D. 1993. Reclamation, Succession, and Mycorrhizae in Alaska. In Papers of the Second EPA
Placer Mine Reclamation Workshop. U.S. EPA publication # EPA 910-R-93-015.
Herkenkoff, E.G. 1987 (December). Snake River Placers Host Elusive Flour Gold. Engineering &
Mining Journal: 42-45.
Holmes, K.W. 1981 (January). Natural Revegetation of Dredge Tailings at Fox, Alaska. In
Agroborealis: 26-29.
Karle, K.F. 1993. Stream and Floodplain Reclamation on Glen Creek in Denali National Park and
Preserve. In Papers of the Second EPA Placer Mine Reclamation Workshop. U.S. EPA
publication # EPA 910-R-93-015.
LaPierriere, J.D., Wagener, S.M. and Bjerklie D.M. 1985 (April). Gold-Mining Effects on Heavy
Metals in Streams, Circle Quadrangle, Alaska. Water Resources Bulletin: 245-252.
Latoski, D. and Chilibeck, B. 1993. Placer Mining and Fish Habitat Restoration in the Yukon In
Papers of the Second EPA Placer Mine Reclamation Workshop. U.S. EPA publication # EPA
910-R-93-015.
Lucas, J.M. 1992 (November). Personal communication between J. Lucas, U.S. Bureau of Mines.
Washington, DC. and G. Weglinski, Science Applications,International Corporation, Denver.
Colorado.
MacDonald, E.H. 1983. Alluvial Mining, the Geology. Technology and Economics of Placers
Chapman and Hall. New York, NY. 508 pp.
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Memorandum. 1988 (August 9). From Paul Baterrun to Pete McGec regarding Public Hearing
Summary.
Park. C F and MacDiarmid. R A. 1975 Ore Deposits, published by W.H. Freeman and Company,
San Francisco
Peterson, J 1993 Mining Methods that Maximize Reclamation Efficiency and Minimize Costs. In
Papers of the Second EPA Placer Mine Reclamation Workshop. U.S. EPA publication # EPA
910-R-93-015.
Polar Mining. Inc. 199la (October 14). Letter from Daniel May to the Reclamation Commissioner,
Division of Mining, with enclosed sketches.
Polar Mining, Inc. 1991b (December 23). 1992 Annual Placer Mining Application (Number
F927278), with attached maps. Signed by Dan May, Operator, Polar Mining, Inc.
Ray. S.R.. Vohden, J. and Morgan, W. 1992. Investigation of Trace Metals Related to Placer
Mining on Fairbanks and Porcupine Creeks. Alaska Division of Geological and Geophysical
Surveys Public-data File 93-13. Fairbanks, Alaska.
Reynolds, J.B., Simmons, R.C. and Burkholder, A.R. 1989 (June). Effects of Placer Mining
Discharge on Health and Food of Arctic Grayling. Water Resources Bulletin: 625-635.
Scannell, P.W. 1993. Natural Recovery of Placer Mined Streams in the Fairbanks and Circle
Mining Districts: Water Quality and Fisheries Perspectives. In Papers of the Second EPA
Placer Mine Reclamation Workshop. U.S. EPA publication # EPA 910-R-93-015.
Silva, M. 1986. Placer Gold Recovery Methods. California Division of Mines and Geology.
Special Publication 87. Sacramento, CA.
Thompson, J.V. 1992 (June). Byproduct Gold From Construction Aggregates. Engineering &
Mining Journal: 49-52.
U.S. Department of the Army, U.S. Army Engineer District, Alaska. 1991 (December 17). Letter
from Timothy R. Jennings to William D. McGee, with enclosed sketches.
U.S. Department of the Interior, Bureau of Land Management. 1993a. Bill Lee, personal
communication with Michelle Stowers, Science Applications International Corporation, June 11,
1993.
U.S. Department of the Interior, Bureau of Land. Management, Fairbanks. 1993b. Personal
communication with Michelle Stowers, Science Applications International Corporation, June 14,
1993.
U.S. Department of the Interior, Bureau of Mines. 1986. "Gold" (by J.M. Lucas). In Minerals
Yearbook, Volume I: Metals and Minerals, 1986. Washington, DC.
U S. Department of the Interior, Bureau of Mines. 1988a. "Gold" (by J.M. Lucas). In Minerals
Yearbook, Volume I: Metals and Minerals, 1988. Washington, DC.
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•Mining Industry Profile: Gold Placers
U S. Department of the Interior, Bureau of Mines. 1989a. Minerals Yearbook - Alaska (by T L.
Pittman). Washington, DC.
U.S. Department of the Interior, Bureau of Mines. 1989b. Minerals Yearbook - Idaho (by R.J.
Minarik and V S. Gillerman). Washington, DC.
US Department of the Interior, Bureau of Mines. 1989c. Minerals Yearbook - Mining Trends in
the Metals and Industrial Minerals Industries (by A.O. Tanner). Washington. DC.
U S. Department of the Interior, Bureau of Mines. 1989d. Minerals Yearbook - Montana (by R.J.
Minarik and R.B. McCulloch). Washington, DC.
U.S. Department of the Interior, Bureau of Mines. 1989e. Minerals Yearbook - Nevada (by F. V.
Carrillo and J.G. Price). Washington, DC.
U.S. Department of the Interior, Bureau of Mines. 1992a. 7997 Annual Report - Gold (by J.M.
Lucas). Washington, DC.
U.S. Department of the Interior, Bureau of Mines. 1992b. Annual Report - Survey Methods and
Statistical Summary of Nonfuel Minerals (by J.A. McCIaskey and S.D. Smith). Washington,
DC.
U.S. Environmental Protection Agency. 1985a (December). Report to Congress: Wastes From
Extraction and Benefidation of Metallic Ores, Phosphate Rock, Asbestos, Overburden from
Uranium Mining, and Oil Shale. EPA/530/SW-85-033.
U.S. Environmental Protection Agency, Office of Water. 1985b. Development Document for
Proposed Effluent Limitations Guidelines and New Source Performance Standards for the Ore
Mining and Dressing Point Source Category, Gold Placer Mine Subcategory (Draft).
U.S. Environmental Protection Agency, Office of Water. 1988a (May). Development Document for
Effluent Limitations Guidelines and New Source Performance Standards for the Ore Mining and
Dressing Point Source Category: Gold Placer Mine Subcategory (Final Draft). Washington,
DC.
U.S. Environmental Protection Agency. 1988b. Economic Impact Analysis of Final Effluent
Guidelines and Standards for the Gold Placer Mining Industry. Office of Water Regulations and
Standards. Washington, DC.
«
U.S. Environmental Protection Agency. 1990a (July). Report to Congress: Special Wastes from
Mineral Processing. EPA/530/SW-90-070C.
U.S. Environmental Protection Agency. 1990b (November 16). 55 Federal Register 222.
U.S. Environmental Protection Agency. 1991 (April). Background Document: Phase I: Regulatory
Strategy For Controlling Small Commercial and Recreational Placer Mining (draft)
U.S. Environmental Protection Agency. 1992a (August). Draft Industry Profile: Gold.
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Mini/if Industry Profile: Gold Placers
U S Environmental Protection Agency. 19925 (August). Agriculture and Wetlands: A Compilation
of Factsheets. EPA 503/9-92-003.
Van Nieuwenhuyse, E. and LaPiernere. J D. 1986 (February). Effects of Placer Gold Mining
Effects on Primary Production in Subarctic Streams of Alaska. Water Resources Bulletin: 91-
Wells. J H 1973 Placer Examination, Principles and Practice. Technical Bulletin 4, U. S.
Department of the Interior, Bureau of Land Management
Whiteway, P (editor). 1990. Mining Explained: A Guide to Prospecting and Mining . The
Northern Miner. Inc. Toronto, Ontario, Canada.
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Mining Industry Profile: Gold Placers
APPENDIX 1-A
ACRONYMS
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Mining Industry Profile: Gold Placers
ACRONYM LIST
A DEC Alaska Department of Environmental Conservation
AMD acid mine drainage
AWQC Ambient Water Quality Criteria
BAT BPJ best available technology/best professional judgment
BLM Bureau of Land Management
BMP best management practice
BPJ best professional judgment
CAA Clean Air Act
CCD continuous countercurrent decantation
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CFR Code of Federal Regulations
CWA Clean Water Act
DHEC Department of Health and Environmental Control
dscm dry standard cubic meter
FLPMA Federal Land Policy and Management Act
FS Forest Service
FWS Fish and Wildlife Service
HOPE* high-density polyethylene
MRS Hazard Ranking System
ICS individual control strategy
IM Instruction Memorandum
kg kilogram
Ib pound
LOEL Lowest-Observed Effect Level
MCL Maximum Contaminant Level
mg/L milligrams per liter
MSHA Mine Safety and Health Administration
NAAQS National Ambient Air Quality Standards
NEPA National Environmental Policy Act
NESHAP National Emission Standards for Hazardous Air Pollutants
NIOSH National Institute for Occupational Safety and Health
NMEID New Mexico Environmental Improvement Division
NPDES National Pollutant Discharge Elimination System
NPL National Priorities List
NPS National Park Service
NSPSs New Source Performance Standards
NTIS National Technical Information Service
oz/t troy ounces per ton
PME Precision Metals Extraction. Ltd.
ppm parts per million
PSD prevention of significant deterioration
RCRA Resource Conservation and Recovery Act
RI/FS Remedial Investigation and Feasibility Study
ROD . Record of Decision
SHDG sediment-hosted disseminated gold
SIP State Implementation Plan
TSCA Toxic Substance Control Act
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Mining Industry Profile: Gold Placers
ACRONYMS (Continued)
TSS total suspended solids
Mg L microgram per liter
USC U S Code
U S DOI • U S Depanment of the Interior
U S EPA US Environmental Protection Agency
USGS United States Geological Survey
VLDPE very low-density polyethylene
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Mining Industry Profile: Gold Placers
APPENDIX l-B
COMMENTS SUBMITTED BY U.S. BUREAU OF MINES
ON DRAFT GOLD PLACER PROFILE
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Mining Industry Profile: Gold Placers
[Comments were not copied for this electronic version
of the Industry Profile. Copies of the comment
document may be received from U.S. EPA, Office of
Solid Waste, Special Waste Branch.]
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APPENDIX 1-C
RESPONSE TO COMMENTS SUBMITTED BY
U.S. BUREAU OF MINES
ON DRAFT GOLD PLACER PROFILE REPORT
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Response to Comments Submitted by
U S. Bureau of Mines
on Draft Gold Placer Profile Report
Written comments on the placer gold mining report were received from the U.S. Bureau of Mines.
Most comments were of a technical nature and were incorporated into the report. However, one
comment made by the Bureau of Mines suggested that the report convert all units of measurement to
the metric system (i.e., weight, length, distance, etc.). The Bureau also suggested the possibly of
including both troy ounces and metric weights. Although much of the industry is moving towards
metric measurements, EPA did not adopt this comment because it was felt that the units used in this
repon are well understood within the placer mining industry; the use of these measurements was only
incidental to the purpose of this report; and the effort needed to convert them to the metric system
was not warranted.
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SITE VISIT REPORTS:
ALASKA PLACER MINES
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Site Visit Reports: Alaska Placer Mines
2.0 SITE VISIT REPORTS: ALASKA PLACER MINES
2.1 INTRODUCTION
This section of the Gold Placer Technical Resource Document presents summaries of three placer
mining operations: Polar Mining Inc.; Alf Hopen; and Cook's Mining. EPA visited these Alaska
placer sites during the summer of 1992 to gain a better understanding of typical placer operations.
The site visit reports are abbreviated due to the relatively limited size of each mining operation. EPA
spent approximately one-half day at each site, viewing the mining and sluicing operations.
2.2 POLAR MINING, INC.
EPA visited Polar Mining's Lower Goldstream Creek operation on July 15, 1992. The following
individuals participated in the site visit: Dan May of Polar Mining, Inc., Kathleen M. Charlie of the
Alaska Department of Natural Resources, Steve Hoffmari'from EPA's Mining Waste Section, and
Ingrid Rosencrantz of SAIC (EPA's contractor).
2.2.1 General Facility Description
The Polar Mining, Inc.'s Lower Goldstream operation is located on private land in Goldstream
Valley, approximately 12 miles northwest of downtown Fairbanks (see Figure 2-1). Originally
patented in 1938 by the Fairbanks Exploration Company, the land on which Polar Mining operates is
now owned by the Alaska Gold Company (Memorandum, August 9, 1988). Donald May, founder
and president of Polar Mining, owns and manages the mine, while his son Dan May acts as vice-
president and maintenance supervisor for the company. Polar Mining commenced work on
Goldstream Creek in 1987. The company "Overview" states that the mine employs 30 local residents
12 months a year on a monthly payroll of over $100,000. The company also operates a gold placer
mine on nearby Fish Creek. ("Overview," August 1, 1988; "Miners rig up converted Cat," April 14,
1991; Polar Mining, Inc., October 14, 1991) , '
Polar Mining's Lower Goldstream operation is the largest open pit placer gold mine in the Fairbanks
area in 1992. The total volume of material mined in 1992, including strippings (soils presumably
used for reclamation) and overburden removed, was 2,200,000 cubic yards. The estimated volume of
material beneficiated during the 1992 mining season was 500,000 cubic yards. Based on this
information, the stripping ratio for the Lower Goldstream operation approached 4:1 (waste:ore). The
total area of the mining operation in 1992, including stripped areas, mining cuts, overburden and
tailing stockpiles and disposal areas, temporary stream diversions, stream bypasses, and settling
ponds, is approximately 29 acres. The estimate does not include the camp and access roads. (Polar
Mining, Inc., 1992 Annual Placer Mining Application F927278)
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Site Visit Reports: Alaska Placer Mines
.SCALE I" = I MILE
Figure 2-1. Polar Mining, Inc., Vicinity Map
(Source: Polar Mining Inc., 1992 APMA)
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Site Visit Reports: Alaska Placer Mines
In 1992, Polar Mining reclaimed 35 acres, both concurrently with mining and at the end of the
mining season. Polar Mining reshaped the reclaimed area to blend with the surrounding physiography
using tailings, strippings, and overburden. The company also stabilized the area so that it will retain
sufficient moisture to allow for natural revegetation. Polar Mining spread stockpiled topsoil,
overburden muck, and, if necessary, settling pond silts, over the contoured mine workings to promote
natural plant growth that can reasonably be expected to revegetate the area within five years. (Polar
Mining, Inc., 1992 APMA)
Unlike most placer mines, the Lower Goldstream operation was active year-round, with the possible
exception of four weeks in late December and early January (Polar Mining's 1992 APMA indicates
that the intended dates of operation are January 20, 1992, through December 20, 1992). Although
the projected dates of operation suggest a year-round mining operation at Lower Goldstream Creek,
the estimated number of sluice days for the 1992 season was 150.
The description that follows applies to the original Lower Goldstream operation as presented in an
"Overview" of Polar Mining's placer mining activities in the Fairbanks area. A 1988 NPDES
Compliance Inspection Report corroborates this account. During the site visit in July 1992, mining
operations resembled those represented in Figure 2-2, only farther upstream.
During the cold winter months when the ground is frozen, Polar Mining used drilling and blasting
techniques to remove frozen silt overburden, and then uses large scrapers to haul the overburden to a
dump site either adjacent to the mine pit or in the immediate vicinity of the pit. According to the
company "Overview," since the frozen silt overburden contains very little moisture, there is no water
or mud discharge into the surrounding lowlands or Goldstream Creek when the overburden thaws in
the spring. During the summer, the scrapers haul the gold placer pay gravels from the bottom of the
pit to a trommel wash plant and sluice box, which is 30 feet wide by 10 feet long. Overburden from
the Lower Goldstream operation consists of gravel to an average depth of 10-30 feet and organic
material to an average depth of 20 feet. Total depth to pay gravel, therefore, is approximately 30-50
feet. ("Overview," August 1, 1988; Polar Mining, Inc., 1992 APMA) , '
Ground water entering the cut provides the source of make-up water, which is generated by seepage
infiltration at an estimated volume of 10 gallons per minute. Goldstream Creek does not supply any
water to the mining operation, nor does it receive any discharges. One hundred percent of the stream
is bypassed by the operation, although the 1992 APMA indicates that channels are planned to connect
obsolete recycle ponds to Goldstream Creek. According to the company "Overview," wash water is
100% recycled and is temporarily contained in these large recycle/settling ponds before it is
transported to the recovery plant. Polar Mining did not use any chemical treatment to extract gold
from the gravels. ("Overview," August 1, 1988; Polar Mining, Inc., 1992 APMA)
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Site Visit Reports: Alaska Placer Mines
Figure 2-2. Sketch of Lower Goldstream Creek Mining Operation
(Source: ADEC, Placer Mine Inspection Form)
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Site Visit Reports: Alaska Placer Mines
Before Polar Mining initiated activity at the Lower Goldstream operation in 1986, the company
relocated the Goldstream Creek channel, diverting the Creek south of the original wash plant location
and settling pond as they are depicted in the 1988 Placer Mine Inspection Form (see Figure 2-2).
Mine cuts now follow the original streambed. At the time of the 1988 sampling inspection, Polar
Mining moved overburden from the mine cut south across Goldstream Creek and stockpiled ore near
the wash plant with scrapers. The wash plant facility consisted of a large trommel and a sluice box.
Discharge from the sluice box is routed to a large recycle pond. According to the 1992 APMA, the
recycle pond was approximately 750 feet long by 500 feet wide by 35 feet deep. A 300-horsepower
pump directed the water to the wash plant through a 12-inch return line at an estimated rate of 3,500
gallons per minute. According to an internal Environmental Quality Memorandum from Paul
Bateman to Pete McGee dated August 9, 1988, Polar Mining used total recycle in its operations and
runs a zero discharge operation. During the 1988 site visit, however, water was being pumped from
the bottom of the pit and was apparently being discharged to the tundra. During the 1992 EPA site
visit, no discharges to tundra were observed. (Overview, August 1, 1988; Polar Mining, Inc., 1992
APMA) '
The 1992 Reclamation Plan provided for two distinct mine cuts labeled 1992-1 and 1992-2 (see
Figures 2-3 and 2-4). Mine cut 1992-1 was scheduled to begin stripping operations in the late fall of
1991, whereas the second proposed cut was optional. (Polar Mining, Inc., October 14, 1991)
The proposed 1992-1 mine cut lies adjacent to and west of the 1991 mine cut. It is estimated to be
1,200 feet long by 450 wide by 35 feet deep, disturbing approximately 12.4 acres. Polar Mining
planned to stockpile material along the north and south sides of the cut to create two topsoil/
vegetation berms, disturbing an additional 2.8 acres. Each berm will each measure 1,200 feet long
by 50 feet wide (at the base) by 12 feet high. Polar Mining plans to deposit the overburden removed
from this cut in the 1991 mine cut, starting from the west side. A portion of the approximately
500,000 bank cubic yards' will also be used in the construction of a wide dike across the 1991 cut,
dividing the cut to form a recycle pond out of the remainder of the cut. The pay gravels will be
concentrated on a pad constructed on top of the dike, and the tailings that are not stockpiled for future
sale will fill in the mined out cuts. (Polar Mining, Inc., October 14, 1991)
Upon completion of the 1992-1 cut, Polar Mining planned to level the berms along the north and
south sides of the cut and forge a connection between the cut and Goldstream Creek, allowing the cut
to fill with water and become a large pond as deep as 25 feet with at least one shallow sloping side.
Polar Mining will also leave the 1992 recycle pond open after contouring the surrounding areas.
'A bank cubic yard is the volume of material, usually pay dirt, equivalent to one cubic yard in situ
(i.e., in its original, undisturbed place in the ground). This volume does not include a swell factor or
reduction in volume resulting from screening.
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Figure 2-3. Plan View of Lower Goldstream Creek Operation, Amended 1992
(Source: Polar Mining, Inc., 1992 APMA)
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Site Visit Reports: Alaska Placer Mines
Figure 2-4. Second Plan View of Lower Goldstream Creek Operation, Amended 1992
(Source: Polar Mining, Inc., 1992 APMA)
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Site Visit Reports: Alaska Placer Mines
Several shallow areas in the pond will be available for waterfowl loafing and feeding. (Polar Mining,
Inc., October 14, 1991)
Adjacent to the east side of the 1990 mine cut is the optional mine cut (1992-2). If mined, this cut
would be approximately 1,100 feet long by 425 feet wide by 57 feet deep, covering about 10.7 acres.
An additional 2.5 acres along the north and south perimeters of the cut will be stockpiled, creating
topsoil/vegetation berms that measure 1,100 feet long by 50 feet wide (at the base) by 12 feet high.
Polar Mining plans to deposit the overburden removed from the optional cut in the de-watered 1991
recycle pond area, completely filling it in. The remainder of the approximately 800,000 bank cubic
yards of overburden would be put in the east end of the 1991 mine cut. Polar Mining would
transport the pay gravels to the 1992 wash plant location and would put the tailings that are not
stockpiled for future use back in the mined out cuts. Polar Mining plans to treat the 1992-2 cut like
the 1992-1 cut upon completion of mining by leveling the berms and connecting the cut to Goldstream
Creek. (Polar Mining, Inc., October 14, 1991)
If the optional cut (1992-2) is not mined, then Polar Mining will smooth the area around the recycle
pond and connect the pond to Goldstream Creek. This pond would also have several shallow sloping
areas that may render it acceptable for waterfowl habitat. (Polar Mining, Inc., October 14, 1991)
More than 10,000 gallons of fuel are stored on-site in above-ground tanks with capacities greater than
660 gallons. Fuel containment berms surround the storage containers, but the berm area was not
lined. A fuel company tanker truck makes an average of 55 trips per year, transporting as much as
8,000 gallons of fuel per trip. The mine site is reached via an existing access road off Murphy Dome
Road. Other equipment used on-site to facilitate overburden removal, beneficiation, and reclamation
activities include two D10 dozers, one Demag H121 excavator, three 773 rock trucks, one 988B
leader, one 235 excavator, one 16G grader, and a blast hole drill rig. On an annual basis, Polar
Mining used 1,200,000 pounds (approximately 600 tons) of explosives to excavate, specifically
ammonium nitrate fuel oil (ANFO). (Polar Mining, Inc., 1992 APMA)
In its proposed 1992 Reclamation Plan (a section of the 1992 APMA), Polar Mining projected that,
given the economic conditions at the time and the mining methods being used, the company was
approaching the end of the current minable ore reserve at the Lower Goldstream Creek operation.
Polar Mining's plans for continued mining operations at the Lower Goldstream mine site beyond the
1992 season were unclear at the time of issuance of the 1992 Reclamation Plan. There was some
discussion of a small underground operation or of continued surface mining on a much smaller scale.
(Polar Mining, Inc., October 14, 1992)
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Site Visit Reports: Alaska Placer Mines
2.2.2 Regulatory Requirements and Compliance
Polar Mining operates its Lower Goldstream mine site with several permits. Polar Mining has been
issued an NPDES Wastewater Discharge Permit (Number AK-004635-3) by EPA.
Polar Mining was first issued the Department of the Army, Corps of Engineers (COE) "404" permit
(Number 4-870729) on September 30, 1988, for the placement of 4,187,100 cubic yards of dredged
and fill material in 98 acres of wetlands to construct a dike, topsoil berms and overburden stockpile
areas, and the placement of fill material for reclamation activities. In December 1989 Polar Mining
requested that a permit modification granting authorization to move the proposed 1990 mining cut
approximately one mile downstream of the area permitted for 1990 and to construct topsoil berms for
the 1991 mining season. The land previously permitted for 1990 was to be left undisturbed. To
facilitate ore access and subsequent reclamation activities, Polar Mining also requested authorization
to create a pad from the majority of the fill material and expressed its intention to stabilize the pad
when it finished mining from that cut. Polar Mining intended to use previous mine cuts as process
water recycle ponds or as receiving pits for material from the next mine cut. Polar Mining stated that
the pad was necessary because not all overburden could be returned to each completed excavation;
overburden material has a swell factor of 30-40%. (Department of the Army, December 17, 1991)
The COE permit (Number M-870729) was modified on January 11, 1990, to the allow Polar Mining
to place approximately 961,100 cubic yards of dredged and fill material into approximately 19.4 acres
of wetlands .to stockpile topsoil and waste barren overburden for the 1990 and 1991 mining cuts. All
other conditions of the original permit remained the same. (Department of the Army, August 22,
1991)
The COE permit was again modified (Number N-870729) on August 22, 1991 to extend the time
limit for completing the authorized work, and the modified permit now expires September 30, 1994.
(Department of the Army, August 22, 1991)
f
The Alaska Department of Fish and Game (ADF&G) issued Polar Mining a permit (Number FG92-
III-0002), informing the company that Goldstream Creek supports resident fish species (grayling) in
the area of the proposed channel excavations from the recycle pond to Goldstream Creek. The
ADF&G advised Polar Mining that the excavations could obstruct the efficient passage and movement
of fish. The ADF&G permit included the following stipulations to reduce potential erosion and
barriers to fish passage (Alaska Department of Fish and Game, January 6, 1992):
I. The outlet channel(s) shall not be connected to Goldstream Creek prior to completion of
mining-related activities in the ponds;
2. The outlet channels shall be excavated to the same depth as the bottom of Goldstream Creek
where the channels enter Goldstream Creek;
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Site Visit Reports: Alaska Placer Mines
3. The outlet channels shall be 12-15 feet wide at the water surface with banks graded to a stable
slope; and
4. The permittee shall plug the outlet channels (with a 100-foot plug) to the original ground
surface level if ADF&G identifies fish entrapment related fish kills within the ponds or
potential fish entrapment related fish fills within the ponds prior to 1995.
Polar Mining does not need a permit from a state or federal land management agency to conduct its
operations because the Goldstream Creek is on private land, although a permit is required from the
COE for the disturbance of wetlands.
EPA is not aware of any state, federal, or local government regulations for mine noise control to the
surrounding community. The Mine Health Safety Administration (MHSA), however, does regulate
noise at mines to protect workers. The MHSA and the Alaska State Mine Inspector inspected the
Lower Goldstream operation on June 25, 1988, and found the mine to be in compliance with all
MHSA safety requirements. Winter blasting was monitored by the State Mine Inspector, who
coordinated with the Pacific Powder Company to take seismic and decibel readings of each blast. The
State Mine Inspector found all blasts to be within the recommended standards of noise and seismic
ground shock for a residential area.
The 1988 "Overview" mentions noise-related problems at the Lower Goldstream operation. A small
group of local Goldstream residents initially opposed the Lower Goldstream operation, their primary
complaint being noise, but their first complaints were about visual impacts. To mitigate these
impacts, Polar Mining constructed a large berm between the pit and the residential area to deflect
noise away from the area homes. Polar Mining also reduced operational hours and the size of the
blasts to minimize their effects. This group of Goldstream residents requested that the Alaska
Department of Environmental Conservation (ADEC) hold a public hearing on the ADEC certification
of the COE permit. The public hearing was held on August 8, 1988 in Fairbanks. The issue of noise
levels was raised, but most concerns involved water quality and wetlands. The State did not take any
action based on this hearing ("Overview," August 1, 1988; Memorandum, August 9, 1988)
(
In Alaska, bonding is required for all mining operations having a mined area of five acres or greater.
The area must be bonded for $750.00 per acre, unless the miner can demonstrate that a third party
contractor can do the required reclamation for less than that amount. Polar Mining submitted
$4,350.00 to the Alaska Department of Natural Resources (DNR) for payment into the State Wide
Bonding Pool to meet the bonding requirements. (Polar Mining, 1992 APMA; Alaska DNR, State
Wide Bond Pool Form)
According to the site manager, at the time of the 1992 EPA visit, the site was in compliance with all
of its permits. (Polar Mining, 1992 APMA; Alaska DNR, State Wide Bond Pool Form)
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Site Visit Reports: Alaska Placer Mines
2.3 ALF HOPEN
EPA visited Alf Hopen's Little Eldorado Creek operation on July 15, 1992. The following
individuals participated in the site visit: the operator Alf Hopen, Kathleen M. Charlie of the Alaska
Department of Natural Resources, Steve Hoffman from EPA's Mining Waste Section, and Ingrid
Rosencrantz of SAIC (EPA's contractor).
2.3.1 General Facility Description
Alf Hopen operated a gold placer mine on Little Eldorado Creek in the Fairbanks mining district near
Cleary, Alaska. The Little Eldorado Creek mining operation is an historic site, as evidenced by Mr.
Hopen's discovery of fire pits at the site that had been used previously to thaw the layer of permafrost
overlying the pay dirt. Mr. Hopen leased the land from the Alaska Gold Company and operated on
both federal and private (patented) claims. The 1992 Reclamation Plan for the Little Eldorado Creek
operation states that the total area to be mined in 1992 is 8 acres, excluding the camp and roads. The
operator conducted reclamation on an equal amount of acreage in 1992, both concurrently with
mining and at the end of the mining season. The topographical map attached to the 1992 Annual
Placer Mining Application (APMA Number F925866) suggests that work is being performed at an
elevation of slightly less than 1,050 feet. The site is fairly steep. Access to the mine site is by means
of existing roads.
Mr. Hopen runs a seasonal operation at the Little Eldorado Creek mine site. He first started mining
at this site on August 15, 1991. The planned dates of operation for the 1992 season are May 1
through October 15, with an estimated 120 sluice days during the season. Three employees work at
the site. The mining operation is projected to be completed in 1992, but if work remains to be done
when the season ends, then mining and reclamation activities will be finished in 1993.
During the EPA site visit on July 15, 1992, Mr. Hopen stated that he moves 1,500 cubic yards of
loose material daily. He estimated that this material comprises 20-30 feet of overburden and 6-8 feet
of pay dirt. The pay strip is narrow with some side pay. Overburden was pushed to the sides, while
a backhoe shovelled the pay dirt to the washing plant, where classification with a shaker screen
precedes sluicing. The 1992 Reclamation Plan states that the total volume of material mined,
including strippings and overburden, is 70,000 cubic yards. It is unclear from the references
available what the ratio is of material moved to material concentrated. The 1992 APMA estimated
that during approximately 120 days, Mr. Hopen will beneficiate 600 cubic yards of material daily,
which amounts to approximately 60,000 cubic yards annually. The estimates from the 1992
Reclamation Plan and APMA for total material mined and total material concentrated (70,000 cubic
yards and 60,000 cubic yards, respectively) suggest a very low ratio of overburden to pay dirt. No
explosives are used at this site.
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The Little Eldorado Creek operation employed two sluice boxes. The larger sluice box measured 20
feet long by 4 feet wide and has a solitary channel. This sluice had 16 feet of double expanded metal
riffles on nomad matting and 4 feet of hydraulic riffles that emit 4 pounds of pressure run over
astroturf matting. The smaller sluice, whose dimensions are 12 feet by 34 inches, also has astroturf
(door mats).
Mr. Hopen did not employ any chemical treatment in his operation. The equipment used on-site
includes a D-8 and D-9 Cat bulldozer, a 980-C Cat loader, a 7/8 cubic yard Insley backhoe, a 1 1/4
cubic yard dragline, a 10x12 pump, and a 6"-pump.
Mr. Hopen had diverted Little Eldorado Creek around the mining operation. According to the 1992
APMA, the diversion ditch provides that 100 percent of the creek bypasses the mine cuts. Mr.
Hopen wanted to operate with 100 percent process water recycle, but actually discharged from the
fourth pond. The source of the make-up water supply is ground water gain from the cut through
seepage infiltration. Make-up water was added 24-hours a day at an estimated rate of 50 gallons per
minute (gpm), or 70,000 gallons per day (gpd). The Placer Plan Review Worksheet indicates that the
sluice flow, which is the amount of water withdrawn, is 2,000 gallons per minute (gpm). The 1992
APMA indicates that the existing dam is 150 feet long by 15 feet high, with the width of the dam at
the base measuring 50 feet and narrowing to 16 feet at the crest, but it is unclear which pond this
dam blocks. The 1992 APMA indicated that Mr. Hopen's operation does not have a discharge. A
narrative attachment to the 1992 APMA and sketch sheet states that settling ponds had to be built
farther downstream than usual in order to create an area sufficiently wide to enable the operator to
safely isolate a creek bypass with no possible future pond erosion problem. Additional settling ponds
will be built in newly mined cuts as mining progresses upstream. The stream will be returned to the
original channel at the end of the mining season as part of the reclamation procedures, at which time
it will be permanently channeled around the settling ponds and stabilized.
There is a large percentage of rock in the tailings that will be left behind in old cuts for stream
channeling as part of the reclamation plan. All discharge water will be filtered through old dredge
tailings after the settling ponds and will not go directly into the creek. The new road will be used as
a dike for a temporary stream bypass. The road will be built on dragline tailings from the old open
cut.
The description of the recycle/settling pond system in the 1992 APMA differs from the EPA site visit
findings. It appears that the operator found it necessary to add a fourth pond to the planned three-
pond system to facilitate settling so that the water would be sufficiently clear for re-use in the washing
plant. The 1992 APMA (and attached sketch) indicates that the operation uses a pre-settling pond, a
small pond (#1), and a larger recycle pond (#2). The site visit revealed that a pre-settling pond was
not used. Instead, the main settling pond, which is 60 feet wide and 6-12 feet deep, overflowed into
a smaller secondary pond below it on the hillside. The secondary pond discharges to the pump (or
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Site Visit Reports: Alaska Placer Mines
recycle) pond, which in turn directs water back to the wash plant for re-use. The recycle pump has
170 horsepower and feeds water through a 12"-line at an estimated rate of 2,000 gpm. In addition to
these three ponds is a fourth (and final) settling pond. The Alaska Department of Environmental
Conservation (ADEC) reviewed the 1992 APMA and found the water control and wastewater
treatment systems adequate.
Fuel was stored onsite in tanks. Fuel containment berms surround the storage area, which were
lined. A fuel truck and offsite storage vessels also function as fuel storage mechanisms.
Approximately 4,600 gallons of fuel may be stored at one time. A tanker truck transports
approximately 4,000 gallons per trip, and the number of trips varies. As part of clean-up, Mr.
Hopen burns and buries garbage. No trash is left lying around. Waste oil is contained and removed
from the mining site.
2.3.2 Regulatory Requirements and Compliance
Mr. Hopen has not received any Notices of Violation (NOVs) with respect to the Little Eldorado
Creek operation, nor has there yet been a Federal inspection.
Mr Hopen operates on Little Eldorado Creek with an NPDES Wastewater Discharge Permit (Number
AK-004451-2) from EPA. He received a turbidity modification for the NPDES permit that was
calculated using a discharge rate of 10 gpm and that permits the discharge of wastewater with a
turbidity of up'to 195 NTU. Discharges (seepage) greater than 10 gpm may require that the
discharge be cleaner than 195 NTU during periods of low creek flow.
Mr. Hopen also has a Corps of Engineers "404" Permit Number (D-890661). ADEC declined to
review or comment on the Little Eldorado Creek activity as it was proposed in the COE permit
application. This non-action constituted a waiver of the state's opportunity to certify the proposed
activity. Any modification to the activity could require future certification.
(•
The Alaska Department of Fish and Game (ADF&G) reviewed the 1992 APMA and decided that £
permit from ADF&G was not necessary for the proposed placer mining operation on Little Eldorado
Creek. The reason given by ADF&G to substantiate this decision was as follows: "The stream is not
known to support fish in the area of your proposed mining activity. Your proposed mining plan does
not indicate activities will occur in waters specified by the Commissioner as important for the
spawning, rearing, or migration of anadromous fish." (Letter from Ron Somerville, Deputy
Commissioner, ADF&G, to Alf Hopen, February 18, 1992)
Al Hopen submitted $1,200 to the Alaska Department of Natural Resources (DNR) for payment into
the State Wide Bonding Pool to meet the bonding requirements of Alaska Statute 27.19 for the
disturbed area sketched and described in the 1992 APMA and Reclamation Plan. Bonding for Federal
claims encompasses the total area of the mining operation, including the camp site, access roads, and
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Site Visit Reports: Alaska Placer Mines
areas to be stripped for mining during the next season. For private claims, bonding covers the active
mining "footprint," which does not include the camp and access roads. It does, however, include all
areas that are part of the mining operation: stripped areas, mining cuts, overburden and tailing
stockpiles and disposal areas, temporary stream diversions, stream bypasses, and settling ponds.
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Site Visit Reports: Alaska Placer Mines
2.4 COOK'S MINING
EPA visited Cook's Mining Fairbanks Creek operation on July 15, 1992. The following individuals
participated in the site visit: the operator John Cook, Kathleen M. Charlie of the Alaska Department
of Natural Resources, Steve Hoffman from EPA's Mining Waste Section, and Ingrid Rosencrantz of
SAIC (EPA's contractor).
2.4.1 General Facility Description
Cook's Mining operated a gold placer mine located approximately 20 miles north of Fairbanks,
Alaska on federal mining claims (F-52493 through F-52500) at the upper head of Fairbanks Creek, a
tributary of Fish Creek, which flows into the Little Chena River. The Steese/White Mountains
District of the Bureau of Land Management (BLM) is responsible for the management of this land
under the General Mining Law of 1872. Patricia S..Franklin owns the claims, and John Cook
operates the mine. The Upper Fairbanks Creek operation is reached by following Steese Highway
north toward deary Summit, and then taking Fairbanks Creek Road five miles east of Cleary
Summit. (Cook's Mining 1992 Annual Placer Mining Application (APMA); Alaska Department of
Environmental Conservation (ADEC), December 19, 1989)
The 1992 mining season represented the fifteenth year of production at the Upper Fairbanks Creek
site, and Cook's Mining anticipated that two years remain before the site will be closed. (Cook's
Mining, March 31, 1992). The 1992 APMA was the source of the following general facility
description.
Cook's Mining operated on a seasonal basis from approximately June 1 through October 1, employing
three to four workers. The company worked an estimated 100 sluice days during the mining season.
The total volume of material to be mined in 1992, including strippings and overburden to be
removed, was 200,000 cubic yards. The estimated volume of material beneficiated during the 1992
mining season was 65,000 cubic yards. Based on this information, the stripping ratio for the Cook's
Mining Upper Fairbanks Creek operation was approximately 3:1 (waste:ore). The total area of the '
mining operation in 1992, including stripped areas, mining cuts, overburden and tailing stockpiles and
disposal areas, temporary stream diversions, stream bypasses, and settling ponds, was approximately
5-6 acres. The estimate does not include the camp and access roads (Cook's Mining, 1992 APMA).
In 1992, Cook's Mining planned to reclaim 10-15 acres, both concurrently with mining and at the end
of the mining season. Cook's Mining will reshape the site to blend with surrounding physiography
using mine tailings and overburden. The company will spread stockpiled topsoil/organic debris over
the reshaped site. Cook's Mining will ensure that fine sediment captured in the settling ponds is
protected from washout and left in a stable condition at the end of the season. Finally, Cook's
Mining will restore disturbed stream areas to facilitate natural restoration of fish and wildlife habitat.
(ADEC, Decision Record, December 19, 1989)
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Site Visit Reports: Alaska Placer Mines
Cook's Mining removed approximately 31 feet of overburden, consisting of 30 feet of gravel and one
foot of organic material. Cook's Mining then fed the pay gravels to a trommel wash plant and sluice
box, which measures 24 feet long by four feet wide and has three channels with a 2:1 slope. Cook's
Mining concentrates an estimated 700 cubic yards of material daily. No chemical treatment is used at
the Upper Fairbanks Creek operation. (Cook's Mining, 1992 APMA)
Ground-water gain from the mine cut and Fairbanks Creek supply the make-up water. Stream flow at
this point in the valley is 300 to 400 gallons per minute, while ground-water infiltration can add
another 50 gallons per minute. The Fairbanks Creek operation has an intermittent, variable
discharge. When Cook's Mining began sluicing for a new cut, it can take up to two weeks for the
stream to fill a new recycle pond. Until the pond fills, there is no discharge; after it fills, there is a
discharge of 300-400 gallons per minute, 24 hours a day, seven days a week.
The operation is near the head of the valley where the stream runs at a low volume. Cook's Mining
needs the stream flow as make-up water for the ponds to^keep up with the outgoing pond seepage that
•s
would diminish the reservoirs if the company diverted the stream around the mine site. However,
Cook's Mining tried to divert the stream to one side of the cut or the other whenever it is feasible so
that the equipment does not run in the stream while mining activities are in progress. Since the valley
is extremely narrow and has steep sides, Cook's Mining cannot make the stream fully bypass the
mining cut or ponds without constructing a large, expensive notch along the length of the south side
of the valley, which would destroy the hillside and would not serve any practical purpose. The
quality of the -water discharge from the mine site has been good enough that Cook's Mining does not
find it necessary to construct such a drastic stream bypass. Fairbanks Creek filters through several
miles of dredge tailings downstream from the Cook's Mining operation, then emerges again as surface
flow. (Cook's Mining, attachment to 1992 APMA; Cook's Mining, "Mining Plans," 1987)
As the mining operations advance, the valley narrows, and the wet groundcover associated with the
bottom of the valley diminishes. As of March 31, 1992, approximately 40 feet of valley bottom
width was considered wet groundcover. Cook's Mining removed this material and stacked it on the
hillside to form an overburden pile 75 feet wide by 1,800 feet long, by 40 feet high. (Cook's
Mining, March 31, 1992)
Cook's Mining operated two pay channels in this valley, one being the lower channel previously
described as having 40 feet of wet groundcover. Cook's Mining was uncovering a bench deposit on
the north slope of the valley. This is a very dry hillside area, and the overburden that is removed
from this bench is pushed directly into the previous bench cut that was just mined. Dry material is
therefore being pushed into a dry hole in the hillside far from the bottom of the valley. (Cook's
Mining, March 31, 1992)
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Site Visit Reports: Alaska Placer Mines
Ponds were planned for the lowest point of the valley on the cleaned bedrock, and six berms will line
the ponds and measure 100 feet long, by 45 feet wide, by 25 feet tall. Cook's Mining will build
these berms using the material previously accounted for in the overburden piles stacked along the side
of the cut on the south side of the valley. (Cook's Mining, March 31, 1992)
The recycle/settling pond system had been built in mining cuts behind the most current operation as it
progresses up the valley. Each pond differs from the others because the overburden from new cuts is
deposited in previous cuts, and then the company builds settling ponds from the area available after it
finishes stripping the cuts. Although the ponds vary significantly, an average set of dimensions for
one of Cook's Mining's settling ponds is 200 feet long by 100 feet wide by 30 feet deep. The recycle
pump is a 60-horsepower instrument that sends an estimated 800 gallons per minute of water through
an 8-inch return line.
There is at least one existing dam and at least one more dam to be constructed. The existing dam is
described as being 150 feet long and 30-50 feet high. The width of the dam is 40 feet at the crest and
75-100 feet at the base.
Approximately 3,000 gallons of fuel are stored on-site in tanks with capacities larger than 660 gallons
and in a tanker on wheels. Fuel containment berms do not surround the fuel storage containers. A
truck from town transports approximately 2,500 gallons of fuel on each of its 10 trips to the site.
Cook's Mining uses the following equipment to accomplish the tasks described: two John Deere 850
dozers to strip and push pay dirt; one Cat 225 excavator to divert the stream, prospect, and sluice;
one John Deere 444 rubber tire loader to move tailings; one D9L Cat dozer for stripping; and
miscellaneous trucks, pumps, and generators to support the stripping and sluicing activities.
2.4.2 Regulatory Requirements and Compliance
Cook's Mining had an NPDES permit (Number AK-004632-9) from EPA. EPA granted Cook's ,
Mining a turbidity modification that allows the company to discharge waste water with a turbidity "of
up to 16 nephelometric turbidity units (NTU), a modification that was calculated using a discharge
rate of 50 gallons per minute. Seepage greater than 50 gallons per minute could require Cook's
Mining to maintain a discharge cleaner than 16 NTU during periods of low creek flow. (ADEC,
April 7, 1992) Since Fairbanks Creek is not known to support fish in the area of the Cook's Mining
operation, the Alaska Department of Fish and Game (ADF&G) did not require a permit.
In Alaska, bonding is required for all mining operations having a mined area of five acres or greater.
The area must be bonded for $750.00 per acre, unless the miner can demonstrate that a third party
contractor can do the required reclamation for less than that amount. Cook's Mining submitted
$2,250.00 to the Alaska Department of Natural Resources (DNR) for payment into the State Wide
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Site Visit Reports: Alaska Placer Mines
Bonding Pool to meet the bonding requirements. (Cook's Mining, 1992 APMA; Alaska DNR, State
Wide Bond Pool Form)
2-18
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Site Visit Reports: Alaska Placer Mines
2.5 REFERENCES
Alaska Annual Placer Mining Application, with attachments, February 3, 1992.
Alaska Placer Plan Review Worksheet, April 3, 1992.
Alaska Department of Environmental Conservation. 1992a (March 20). Letter from William D.
McGee, Alaska Department of Environmental Conservation, to Alf Hopen.
Alaska Department of Environmental Conservation. 1992b (April 7). Letter from William D.
Morgan, Alaska Department of Environmental Conservation, to Alf Hopen. i
Alaska Department of Environmental Conservation. 1992c (April 7). Letter from William D.
Morgan to John Cook, Cook's Mining.
Alaska Department of Environmental Conservation. December 19, 1989. Decision Record, with
attachments.
Alaska Department of Environmental Conservation. June 3, 1988. Placer Mine Inspection Form,
with an EPA NPDES Compliance Inspection Report cover sheet dated August 2, 1988 and
signed by Conrad Christiansen.
Alaska Department of Fish and Game. 1992a (January 6). Letter to Dan May, Polar Mining, Inc.
Alaska Department of Fish and Game. 1992b (February 18). Letter from Ron Somerville, Alaska
Department of Fish and Game, to Alf Hopen.
Alaska Division of Mining Approved Reclamation Plan, approved by John E. Wood, May 6, 1992.
Alaska Department of Natural Resources Case File Abstract, February 21, 1992.
Alaska Department of Natural Resources State Wide Bond Pool Form, April 27, 1992.
Alaska Department of Natural Resources. 1988 (August 1). "Overview: Polar Mining, Inc." An
executive summary of the Lower Goldstream operation faxed from the Alaska Department of
Natural Resources. ,
*•
Cook's Mining. 1987. "Mining Plans." Letter from John Cook; recipient unknown.
Cook's Mining. 1992a (January 6). 1992 Annual Placer Mining Application (Number F926973),
with attachments. Submitted to the Alaska Department of Environmental Conservation by John
Cook.
Cook's Mining. 1992b (March 31). Letter from John Cook to Kevin Morgan, Department of the
Army.
Memorandum. August 9, 1988. From Paul Bateman to Pete McGee regarding Public Hearing
Summary.
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Site Visit Reports: Alaska Placer Mines
Polar Mining, Inc., 1992 Annual Placer Mining Application (Number F927278), with attached maps.
December 23, 1991. Signed by Dan May, Operator, Polar Mining, Inc.
Polar Mining, Inc. October 14, 1991. Letter from Daniel May to the Reclamation Commissioner,
Division of Mining, with enclosed sketches.
United States Department of the Interior, Bureau of Land Management. Environmental Assessment
(EA Log Number AK-080-89-041).
U.S. Department of the Army, U.S. Army Engineer District, Alaska. 1991 (August 22). Permit
modification issued by Timothy R. Jennings to Polar Mining, Inc.
U.S. Department of the Army. December 17, 1991. Letter from Timothy R. Jennings to William D.
McGee, with enclosed sketches.
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Site Visit Report: VaUez CreeJc Mine
SITE VISIT REPORT:
VALDEZ CREEK MINE
CAMBIOR ALASKA INCORPORATED
-------
Site Visit Report: Valdez Creek Mine
3.0 Srre VISIT REPORT: VALDEZ CREEK MINE CAMBIOR ALASKA INCORPORATED
3.1 INTRODUCTION
3.1.1 Background
The U.S. Environmental Protection Agency (EPA) is currently developing a mining program under
the Resource Conservation and Recovery Act (RCRA). To date, EPA has initiated several
information gathering activities to characterize mining wastes and mining waste management
practices. EPA has also chartered a Policy Dialogue Committee under the Federal Advisory
Committee Act to encourage discussion of mining-related issues by representatives of EPA and other
Federal agencies. States, industry, and public interest groups. As part of these ongoing efforts, EPA
is gathering data related to waste generation and management practices by conducting visits to mine
sites. As one of several site visits, EPA visited the Valdez Creek Mine on July 13, 1992.
Sites to be visited were selected by EPA to represent both an array of mining industry sectors and
different regional geographies. All site visits have been conducted pursuant to RCRA Sections 3001
and 3007 information collection authorities. When sites have been on Federal land, EPA has invited
representatives of the land management agencies (Forest Service/Bureau of Land Management). State
agency representatives and EPA regional personnel have also been invited to participate in each site
visit.
For each site, EPA has collected information using a three-step approach: (1) contacting the facility
by telephone to get initial information, (2) contacting state regulatory agencies by telephone to get
further information, and (3) conducting the actual site visit. Information collection prior to the site
visit is then reviewed and confirmed at the site.
In preparing this report, EPA collected information from a variety of sources including Cambior Inc.,
and the State of Alaska. The following individuals participated in the Valdez Creek Mine site visit on
July 13, 1992:
Cambior Alaska. Incorporated
Bob Walish, General Manager 907-694-4653
U.S. Environmental Protection Agency
Steve Hoffman, Chief, Mine Waste Section, Office of Solid Waste 703-308-8413
Science Applications International Corporation
Ingrid Rosencrantz, Environmental Scientist 703-734-2508
3-1
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SUe Visit Report: Valdez Creek tiine
3 1.1.1 General Description
The Valdez Creek Mine was the largest placer gold mine in North America in 1992 and is operated
by Camhior Alaska, Incorporated. The operation is owned by Camindex Mines (25 percent share
holder) and Cambior Alaska. Incorporated (75 percent share holder). The operation is located near
Cantwell. Alaska. 110 miles south of Fairbanks, along the Denali Highway (Figure 3-1).
The mine extracted loosely consolidated alluvial material from the valley bottom to a depth of 180 to
200 feet. Gold bearing pay-gravel is passed through a wash plant (a sluice system) to gravity
concentrate the gold. Additional gold concentration is conducted using a jig, Knudsen bowl and
magnetic separation.
Typically, pay-gravels have been located in deeply-buried paleochannels north of the active channel of
Valdez Creek. However, in the area where mining was taking place, the active channel of Valdez
Creek converges with the area to be mined, overlying the paleochannels. In order to access portions
of the mine, the facility had diverted Valdez Creek around the mine. Diversion structures include a
diversion dam, spillway and ditch.
The facility held placer mining claims in the area that cover 19,880 non-contiguous acres of Federal
Land under jurisdiction of the Bureau of Land Management. According to facility personnel, the
most recent active operations are currently disturbing approximately 67 new acres of BLM land, not
including land previously disturbed. As shown in Figure 3-2, the total area of land disturbed at the
mine, including past mining activity, is on the order of 807 acres (BLM 1990). In addition to Valdez
Creek Mine, there are other smaller mines further up the Valdez Creek valley.
Open pit mining began at the site in 1984. Cambior Incorporated purchased the existing mining
operations in November 1989 and shut down the operation in November 1990 to construct a new
wash plant and settling/tailings impoundments (Cambior, 1991). According to facility personnel, the
operation reopened in August 1990, with mining in the A7 pit beginning in March 1991.
Mining began in the area in 1903, with the discovery of placer deposits. After a small "rush" in
1904 and 1905, mining activity in the area was variable with techniques such as drift mining,
booming and hydraulicking used to access and excavate the pay dirt. According to the Environmental
Assessment, three different mining companies held the Valdez Creek property from 1913 to 1949 and
conducted a considerable amount of mining. Mining in the area was substantially reduced until open
pit mining began in 1984.
3-2
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Site Visit Report: Valdez Creek Mine
Figure 3-1. Facility Location Map
(Source: Environmental Assessment 1990)
3-3
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Site Visit Report: Valdez Creek Mint
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3-4
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Site Visit Report: Valdez Creek Mine
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3-5
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Site Visit Report: VaUez Crtek Mine
3.1.2 Environmental Setting
The mine is located in the Clearwater Mountains area, part of the Alaska Range. Valleys in the
region uere occupied by the Susitna. West Fork, and Valdez Creek glaciers during past periods of
glaciation. Glacial features in the valley include medial, lateral, end, and ground moraines. Valdez
Creek is a tributary to the Susitna River; the Susitna River flows into the Cook inlet on the south
coast of Alaska. The mine is located at approximately 3,000 above sea level. The climate is harsh
during most of the year, with extreme cold conditions from October through April or May.
Temperatures range from summers highs in the 50's to winter lows in the -40's range (Valdez Creek
Mining Co 1988) Mean annual precipitation is estimated to be between 10 and 12 inches per year.
Most of this falls as snow from February through May. The Environmental Assessment (BLM 1990)
estimated that up to 9 inches of the annual precipitation budget (12 inches) is lost by sublimation and
evapotransporation, and that 2.4 inches run off via Valdez Creek, the remainder recharges ground
water.
Vegetation is typical of cold climate species. In the valley bottom, conifers (scattered black spruce)
are mixed with grasses and alder. Further up the valley slopes, the vegetation grades into tundra
species including dwarf birch, mountain avens, dwarf willows, cranberry, and other species. There
are no threatened or endangered plant species in the area. (BLM 1990)
Wildlife in the area include caribou, moose, wolf, black and brown bear, fox, and beaver. None of
these species occur in large numbers and according to site personnel, no threatened or endangered
species occur in the area. Valdez Creek supports populations of grayling and lake trout. The stream
diversion required to conduct mining activity in pits A-7 through A-10 resulted in the operator having
to transport the fish around the diversion. Grayling migrate upstream in the spring, following
breakup, for spawning. The fish are captured in a pool located below the mine and are trucked a
short distance up stream. (BLM 1990)
3.1.2.1 Geology
The geology at the site consists of poorly-sorted glacial and fluvial material deposited above bedrock.
The sedimentary deposits consist of glacially worked alluvial and fluvial sediments deposited by the
Susitna, West Fork and Valdez glaciers during past glaciation (Valdez Creek Mining Co. 1988)
Material from volcanic ash outfalls are also present in the area.
The site contains paleochannels cut during interglacial periods by the ancestral Valdez Creek. Thes«
channels contain the sediments (fluvial deposits) where placer gold material has been naturally
concentrated (Figure 3-3). This material is sometimes referred to as pay-gravel or pay-dirt.
Overlying these are the lacustrine and outwash features characteristic of a glacial environment.
Height of the section above bedrock averages 200 feet.
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Site Visit Report: Valdez Creek Mine
Figure 3-3. Typical Cross Section of Pits A-6 Through A-10
(Source: Valdez Creek Mining Company, Plan of Operations)
3-7
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Site Visit Report: Valdez Cnek Mine
There are two pay gravel deposits mined at the site. The main deposit conforms to the bedrock floor
and is approximately 20 feet thick, while a second newer deposit is in a canyon incised in the main
deposit that reaches an additional depth of 40 feet. Where possible, both deposits are mined;
however, the difficulty of delineating the newer deposit because of its irregular channel path often
results in leaving the deposit unmined.
Soils are typical of cold climates at high altitudes and latitudes. Dominant soils are Histic and
Pergelic Cryaquepts that are wet during the summer. Soils are prone to high runoff and erosion
because they have a low permeability and slopes in the Valdez Creek valley are high. Topsoil in the
area is very shallow and generally nutrient deficient. Although permafrost does occur in the area,
none has been encountered at the Denali Mine (BLM 1990).
3.1.2.2 Surface Water
The Valdez Creek valley watershed covers an area of 60 square miles. The Creek flows 17 miles
from Grogg Lake to the Susitna River. Mining operations are concentrated on the lower portion of
the valley, two miles upstream from the Susitna River. In this area, Valdez Creek has been diverted
by the mining company in order to access to ore beneath the active stream channel (see Section 3.2).
A diversion dam has been constructed upstream of the active pit. The dam impounds water, which
then flows through the diversion channel approximately one mile until rejoining with the stream. The
diversion channel is lined and covered with rip-rap. The Creek is then returned to its original
channel below the mine, before entering the Susitna River. In addition to the Creek diversion system.
the facility has two small diversion ditches on either side of the valley to intercept runoff before it
reaches the pit. Water from these diversion ditches flows to two settling ponds.
Over most of its course, Valdez Creek flows as a single, confined channel. The channel is braided
above the diversion dam and then from below the mine to its confluence with the Susitna River.
Background water quality tests in the stream show a turbidity of 0.4 nephelometric turbidity units
(NTU), with settleable solids of less than 0.1 ml/1. Storm runoff can increase these levels to 1.500
NTU, with settleable solids reaching 10.3 ml/1. (BLM 1990)
Discharge from the Creek is estimated to be 300 cubic feet per second (cfs) in late March and up to
900 cfs in late May and early June. The 25-year flood is estimated to flow at 2,700 cfs. All of the
facilities are within the 100-year floodplain. (BLM 1990)
3.1.2,.3 Ground Water
As discussed above in the geology section, the site is underlain by unconsolidated glacial and fluvial
material above bedrock. Till is interbedded with lenses of gravel in the upper portions of the profile
that discharge an estimated 10 to 30 gallons per minute (gpm) of ground water. In the area just
above the bedrock, a 10 foot zone of gravel, cobbles, and boulders discharge up to 50 gpm. (BLM
3-8
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Site Visit Report: Valdez Creek Mine
1990) Transmissivity in the till is estimated to be approximately 10"3 cm/sec (Valdez Creek Mining
Co 1988). According to the facility's Solid Waste Permit Application, the regional water table is a
ten or more feet into the bedrock, 170 to 200 feet below the surface and water production is limited.
Additional information concerning the hydrologic regime at the site was not obtained.
The facility operated eight dewatering wells that pump ground water from the area prior to and during
mining. According to facility personnel, five wells are located above the diversion dam, which is
upstream of the active pit, and 3 wells are located below the dam in the mine area. The water was
discharged to the diversion system directly below the diversion dam. Additional information on these
8 dewatering wells was not obtained.
The facility operated three drinking water wells onsite. Wells A and B provided less than 10 gallons
per minute and were used during normal operations. Well C was only used during winter operations.
Well water was tested monthly for coliform, quarterly for volatile organics and once every 4 years for
gross a. Depths of these wells and results of the testing were not obtained.
3-9
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Silt Visit Report: Valdez Creek Mine
3.2 FACILITY OPERATION
3.2.1 General Overview
Cambior's Valdez Creek Mine recovered over 75,000 ounces of gold annually, making it the largest
placer operation in North America in 1992. Reserves are estimated to be 216.843 raw ounces with
grades that average O.I ounces per cubic yard. Typically, mining progressed up the valley, with ore
hauled by truck to a wash plant for gravity concentration and waste rock trucked to backfill
previously excavated pits. The Plan of Operations for the period from 1990 to 1994 called for
moving 35,590,000 cubic yards of overburden to access 4,450,000 cubic yards of pay gravel.
According to Cambior personnel, the Company employed 155 people onsite and operated 365 days
each year. Two shifts ran each day for 10.5 hours. Three crews cycle in and out: 14 days on, one
week off. Accommodations for the crews are ATCO trailers purchased from the Alyeska Company,
where they were used along the Trans-Alaska Pipeline. Some employees prefer to live offsite in a
camp on BLM land close to the facility referred to as Little Idaho. Water, sewage, and electricity is
supplied by the facility.
3.2.2 Extraction
As discussed above, open pit mining of paleochannels north of Valdez Creek began in 1984.
Camindex Mines has been a partial owner since the start of the project (at various percentages).
Cambior acquired a 26 percent share of the mine in 1989, 49 percent in May 1990, and, effective
January 1991, the ownership is: Cambior 75 percent, Camindex 25 percent. In August 1990 the
operators shut down the operation to make operational changes. Until then, pay-gravels had been
located in deeply-buried paleochannels separate from the active channel of Valdez Creek. However,
as mining progressed up-valley, the paleochannels converged with the active channel of Valdez Creek.
In order to access the ore, the facility constructed a diversion system for Valdez Creek. During this
same inactive period, the facility also constructed a new wash plant and settling impoundments. Upon
completion of construction in March 1991, mining began again with excavation from Pit A7.
3.2.2.1 Excavation
The Operating Plan for 1990 through 1994 laid out the progression of mining activities. Figure 3-2 is
a plan view of pit, waste, tailing, and facility building locations. The acreage for each use is
identified, total area for all the activities identified is 807 acres. The operation was mining in the
area A-7 (labeled area V and located at the top of the figure), and continuing upstream through A-10.
Table 3-1 provides the estimated volume of overburden and pay gravels in each of these areas.
Pit A7 was being mined in 10 phases, with 2 or 3 phases in operation at any one time. Each phase of
the current pit is 400 to 650 feet wide (in the direction perpendicular to the stream channel), 180 to
200 feet deep, and 400 to 600 feet long.
3-10
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SiU Visit Report: Valdei Crtek Mint
Table 3-1. Estimated Volumes of Overburden and Pay-Gravel
(Source Valdez Creek Mining Company. Plan of Operations)
MASS BALANCE
DENALI MINE 1990-94
PIT NAME
Acreage
Overburden
Cu. Yd.*
Pay Gravels
Cu. Yd.*
OC-1
6
640
no
A-7
67.3
9100
700
A-8
70.2
9100
740
A-9
80.2
8250
1600
A-10
22.3
8500
1300
Totals
246
35590
4450
In thousands
3-11
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Site Visit Report: VaUez Creek Mine
At any one time, there was approximately 1,200 feet of open cut (e.g.. a 1,200 foot length of valley
bottom. 400-650 foot wide) being mined and backfilled. The top 180 feet of material is waste rock
with pay gravel reaching a depth of 20 feet below the waste rock. The facility was extracting an
average of approximately 34,000 cubic yards of material each day. Of this, 3,000 cubic yards pass
through the wash plant when it is operating, leaving approximately 90 percent of the material moved
as waste
There were two pay gravel deposits in the area of Pit A7. The main deposit conforms to the bedrock
floor, while a second newer deposit is in a canyon incised in the main deposit that reaches an
additional depth of 40 feet. Where possible, both deposits are mined; however, the difficulty of
delineating the newer deposit because of its irregular channel path often results in leaving the deposit
unmined.
Initially the area was dewatered by pumping from withdrawal wells located near the diversion dam.
Before excavating, a new section is drilled and blasted using ANFO to loosen or "fluff up" the
unconsolidated material thereby making it easier to load and haul. The Company purchased
ammonium nitrate and mixes it with fuel oil onsite. Waste rock is then mucked up and trucked to
previously mined pits for disposal. The company used two front shovels, one with a 13-yard3 bucket
and one with a 11-yard3 bucket and a Caterpillar front-end loader with a 12-yard3 bucket to muck
waste rock, and eight 85-ton Caterpillar trucks to haul the waste rock. Pay gravel was mucked with a
backhoe having either a six-yard3 or nine-yard3 bucket and trucked to the wash plant. Usually smaller
50 ton trucks are used to haul pay dirt. The facility also used four dozers to work the dumps and the
roadways.
3.2.2.2 Water Management
During the site visit, EPA observed water in the bottom of the pit and noted the plasticity of the soils
as trucks traveled in the area. According to facility personnel this is due to characteristics of the
glacial till overburden. To help with water management in the active area of the pit, the facility
maintained two small diversion ditches on either side of the valley above the mined area to intercept
runoff before it reaches the pit. In addition, the area to be mined was dewatered by eight ground
water wells. Water from these wells is pumped to the diversion channel. According to facility
personnel, five wells are located above the diversion dam above the mine and three wells are located
below the dam. The water was discharged to the diversion system directly below the dam.
Additional information on these eight dewatering wells was not obtained.
To access pay-gravels in pits A-7 through A-10 a temporary stream diversion was built. According to
facility personnel, the diversion dam, is approximately 200 feet wide and over 25 feet tall with a crest
width of approximately 50 feet (the dam was observed during the site visit). The^area impounded
during breakup reaches a maximum of approximately 100 acres, two to three times the normal
impoundment size of 25 acres. Typically, the water is only a few feet deep; however at breakup it
3-12
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Sir* Visit Report: Valdez Crtek Mine
may reach 10 feet in depth. The diversion ditch leads approximately 5.000 feet downhill, from the
diversion dam to where it discharges to the creek. The entire diversion ditch is lined with a synthetic
liner and rip-rap to prevent erosion and downcutting.
Peratrovich. Nottingham & Drage, Inc. were retained to prepare an engineering study for the
diversion The final design allowed a two stage implementation. Stream flow would be diverted to a
channel 500 feet south and parallel to the natural stream. The stage I channel would be 5,385 feet
long and the stage II channel would be 5,385 feet long for a total length of 10,755 feet. The channel
invert was planned to be 20 feet wide at the base and 30 feet wide to the top and 2 to 2.5 feet deep.
The diversion channel was to be designed to accommodate flow up to 2,700 cfs, equivalent to the 25
year flood event. Average flow is expected to be 700 cfs.
3.2.3 Beneficiation
The wash plant that concentrates the gold is strictly a mechanical system, no chemical additives were
used. Additional gold concentration is conducted in a guarded and secured room using a jig, Knudsen
bowl, table, and magnetic separation.
Pay-gravel was delivered to the wash plant by truck and dumped into a vibrating grizzly feeder.
Water is added to the grizzly through pipe-mounted sprayer heads at the rate of 1,500 gallons per
minute. The grizzly discards material larger than six inches in diameter. Material less than six
inches in diameter passes to double-deck vibrating screens. Additional water is added to the screens
at the rate of approximately 1,500 gallons per minute. The screens reject material larger than 3/4
inches in diameter. This material is carried by conveyor to a pile and is used by the facility for road
repair. The facility does not have nugget trays to separate nuggets from the waste rock; they are
assessing whether it would be economical to install them.
Fine material passing the screens is passed to a make-up tank where water may be added to make a
slurry of 14 to 20 percent solids. According to facility personnel, the wash plant operation used
approximately 3,000 gpm of water; most of this is added by spray bars at the grizzly and vibrating
screen. From the make-up tank, a Warman slurry pump transfers the slurry to a series of sluices.
The wash plant is operating with seven sluice boxes. Two types of sluices are used: five are 34 feet
long, sloping 1.25 inches per foot. Four of these are running at any one time. Hungarian riffles are
1.5 inches high and are spaced two inches apart. Below the riffles, the lower 20 percent of the
sluices are fitted with expanded metal over astrorurf. Two newer sluices use a modified Hungarian
riffle one inch high spaced one inch apart. The slope is two inches per foot in the riffle portion and
1.25 inches per foot in the expanded metal portion. A Nomad matting is used under the expanded
metal section.
The sluices serve to allow the gravity concentration of gold from other less dense particles. No
chemicals are added; the operation is entirely mechanical. The relatively more dense gold
3-13
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Site Visit Report: Valdez Creek Mine
accumulates in the lee of the riffles and in the matting, with the remainder of the slurry (water and
less dense gangue) flowing over the riffles to become tailings. Tailings from the sluice boxes empty
into a pump box where they are pumped to one of three settling ponds (also called tailings ponds).
The sluices were shut down and cleaned of gold every one or two days. Matting is picked and
washed. The material is put in buckets and carried to the gold room. In the gold room, magnetic
separation is used to separate heavy minerals such as magnetite from the gold. Following this, a jig,
a table, and a Knudsen bowl are used to further separate gold from gangue. In a jig, slurry flows
horizontally through a box with a screen top through which water is pulsed, separating more dense
from less dense material. A table is an inclined table with small channels. The quantities of waste
generated in this operation were not obtained; however quantities are minimal compared to the
amount of tailings generated.
As discussed above, tailings were sent to settling ponds. There are three settling ponds in this
system; the system is designed to allow settling of tailings and recycling of the water to the wash
plant. Two ponds are unlined and the dam on the remaining pond is lined at one end of the pond.
The operation discharged a low solids slurry from the wash plant into the primary sluice pond, which
discharged to the secondary sluice pond and then to the tertiary sluice pond, where water is
reclaimed and pumped back to the wash plant operation. These ponds are actually old mining pits A4
and A3 and are called the E4 and ES wash plant ponds by the facility. According to facility
personnel, each was approximately five acres in size with the deepest being 20 feet and the others
ranging in depth from five to 10 feet. The ponds had a total capacity of 340 acre-feet (Cambior
1990). This pond system is intended to totally recycle all wash plant water. In addition to wash plant
water, effluent from dewatering the pit was also discharged to these ponds (Cambior 1990).
Cambior had structural integrity problems with the first pond. This pond has failed twice, in 1991
and 1992. At the time of the site visit, the pond had been reconstructed and lined and Cambior was
refilling the pond with water to test its integrity. Cambior expects a final permit for this pond when
the construction is finished. These pond failures are discussed in more detail in Section 4.
As discussed above, water use in the wash plant was estimated by facility personnel to be
approximately 3,000 gpm. Water sources for the operation include recycled water from the sluice
ponds, which constitutes about 90 percent of the total flow. The remaining flow is make-up water
from Valdez Creek (BLM 1990). Figure 3-4 is a diagram showing the 1990 through 1991 water
balance according to the Environmental Assessment. Note that the total volume used at the wash
plant estimated in the Environmental Assessment differs from the estimate provided for current usage.
3-14
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Stic Visit Report: Valdez Creek Mi/ie
IOO-IOOO
900
9OO- HOC
MCCrCLC
1992-1994 WATER
VALUEZ CREEK MINING
Figure 3-4. Water Balance for 1990 Through 1991
(Source: EA 1990)
3-15
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Site Visit Report: Valdez Creek Mine
32.3.1 Ancillary Facilities
If the plant is shut down or if there is excessive runoff, the settling ponds discharge to a system of
older settling ponds (called the Willow Creek Ponds). These ponds are old settling ponds that were
constructed during previous operations.
Any discharge from the new settling pond system is routed through a series of ditches to the
uppermost pond of the old pond system, which consists of six ponds. Discharge to the Creek from
the old system is through an outlet from the Willow Creek Number 1 dam, the NPDES discharge
point. (Cambior 1990)
A pump station has the capacity to supply 4,400 gpm to the plant. More detailed information on the
pump station was not obtained. The facility operates three diesel boilers to provide steam during
winter operations. There are steam lines under the ore pile keep the ore pile from freezing.
3-16
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Site Visit Report: Valdez Creek Mine
3.3 MATERIALS AND WASTE MANAGEMENT
Wastes and materials managed onsite at the Valdez Creek placer mine include large volumes of waste
rock and tailings, as well as used or spilled material not uniquely related to mining. In addition other
materials, such as mine water are generated onsite. Because these material ultimately become wastes
when intended for disposal, they are also addressed here.
3.3.1 Waste Rock
Waste rock was generated during excavation of the pit and consists of overburden removed to access
the ore. Waste rock typically consists of poorly sorted glacial material with some lenses of well
sorted gravels and cobbles. As discussed previously, according to the Environmental Assessment, the
facility extracted approximately 34,000 cubic yards of material each day. During operation,
approximately 3,000 cubic yards passed through the wash plant per day. According to facility
personnel, the waste to ore ratio is about 11 to 1. Table 3-1 provides the estimated volume of
overburden and pay gravels in each of the planned areas. Based on Table 3-1, the stripping ratio for
Pit A7 is approximately 13:1 (waste to ore).
Most waste rock is used to backfill older pits, however, there is always an amount remaining to be
disposed of elsewhere due to swelling caused by the excavation. The swell factor or ratio for
materials at this site was not obtained. The excess waste rock is piled onsite. As discussed later in
this section, a solid waste landfill is located on one of the waste rock piles. Chemical analysis of the
waste rock was not obtained.
3.3.2 Tailings
Tailings generated at the Valdez Creek Mine can be categorized into three types: one type consist of
oversize material generated during the initial stages of washing; a second type, consists of a low solids
slurry generated as discharge from the wash plant; the third type is generated during final
concentration of the gold in the gold room. The volume of tailings generated from each different part
of the operation varies greatly, with discharge from the wash plant at a rate of 3,000 gpm, while
tailings from the final concentration may be measures in terms of buckets per day.
Tailings separated during initial stages of washing include anything larger than 3/4 inches. This
material is generated at both the grizzly (material greater than 6 inch) and the vibrating screens
(material greater than 3/4 inch) of the wash plant. Tailings may also contain gold nuggets, discarded
from the washplant due to size. According to the facility this material was stored in piles and used to
maintain roads onsite. Tailings from the final stages of concentration, where gold concentrate is
further separated from gangue using magnetic separation, a jig, a table, and a Knudsen bowl, consist
of fine gangue minerals. This material was poured back into the system at the top of the sluice.
3-17
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Site Visit Report: VaUez Creek Mitte
The highest volume of tailings generated was the low solids slurry discharged from the wash plant to
the sluice ponds. The slurry consists of the less dense gangue minerals (all material less than 3/4 inch
that was introduced to the wash plant) and water. Because no chemical additives are used in the wash
plant, none are expected in the tailings. Constituent analysis of the water was not obtained.
As discussed previously, these tailings were discharged to a settling pond system. After settling,
process water is then reused in the wash plant. The settling pond system is made of three settling
ponds in a series with water pumped back to the wash plant from the third pond; only the dam
between the first and second pond is lined. According to facility personnel, the ponds were
constructed in two old mining pits; each is approximately five acres in size with the deepest being 20
feet and the other two ranging in depth from five to 10 feet. The ponds have a total capacity of 340
acre-feet (Cambior 1990). Dam and other construction-related details were not obtained. This pond
system is intended to totally recycle all wash plant water. In addition to wash plant water, an
unspecified volume of effluent from dewatering the pit is also discharged to these ponds (Cambior
1990). Information was not obtained on the estimated amount of water lost to seepage from this pond
system.
Although the settling pond system is generally operated as a zero discharge system, during periods of
high runoff or plant shutdown, excess water is routed through ditches to the uppermost of six
additional settling ponds (Cambior Mining 1990). The lowest of the ponds discharges wastewater to
Valdez Creek through a NPDES discharge point. These ponds, called the Willow Creek Ponds, allow
additional settling of suspended solids prior to discharge to the Creek. Originally, the ponds were
used as settling ponds during previous operations. According to facility personnel, the Willow Creek
Ponds are constructed on native compacted soil. At the time of the site visit, the facility was not
using the wash plant so mine water and other process water was being discharged to these ponds
rather than being pumped back to the wash plant.
The size and theoretical efficiency of these settling ponds is presented in Table 3-2. The
Environmental Assessment and Facility personnel identify five ponds while a letter from Cambior to
EPA Region 10 identifies six ponds. According to facility personnel, the additional pond is a small
mining pit that water flows through before it reaches the willow creek ponds. Information on the
quantity and frequency of settling pond discharge to these settling ponds was not obtained. However,
discharge from the lowest pond in the Willow Ponds system through the NPDES discharge point is
presented in Table 3-3. This discharge is monitored for arsenic, settleable solids and turbidity.
According to a single sample taken (date of sampling not obtained), both turbidity and arsenic were
slightly above background levels but well below NPDES limits. (Cambior 1990) See Section 3.4 for
more information on NPDES compliance.
3-18
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Site Visit Report: Valdez Creek .Wine
Table 3-2. Theoretical Efficiency of Settling Ponds
(Source: BLM 1990)
Theoretical Efficiency of Settling Ponds
at Oenali Mine (existing)
Structure
Settling Pond #1
Settling Pond »2
Settling Pond *3
Settling Pond «4
Settling Pond *S
Surf act Area
(acres)
3.90
3.80
4.20
16.9
8.50
*Water Flow
(gpm)
5000
1000
4400
5000
1000
4400
5000
1000
4400
5000
1000
4400
5000
1000
4400
**Overflow
(gpm/ A)
1282
256
1128
1316
263
1157
119?
238
1047
295
59
260
5S8
118
517
Process water rate through system. Maximum flow 5000 gpm, minimum
probable 1000 gpm, design flow 4400 gpm.
To obtain adequate sedimentation, the settling pond i* recommended to
have an overflow rate of not more than 3700 gal/min/acre. (The
overflow rate is the flow rate di ded by the surface area of the
settling pond.) To obtain maximum sedimentation, the overflow rate
should not be more than 860 gal/min/acre.
3-19
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Site Visit Report: Valdez Creek .Wine
Table 3-3. NPDES Discharge Rates
(Source Cambior 1990)
INiTAMTAJIIOOl DAILY FLOW MZAJURJdim'
WILLOW CRUX MINI WO. 1 OXiCXAJtGI 7Z1I
(OVK)
XOMTU OF!
OATI
1
2
1
4
3
•
7
•
t
10
11
12
13
14
IS
14
17
It
If
20
21
22
SEPTEMBER
2268
2213
2268
1290
1172
574
179
134
N.R.1
17
17
17
17
134
ocrom
63
N.R.
N.R.
N.R.
17
5
17
17
17
17
17
M.R.
N.R.
17
N.R.
37
N.R.
17
17
5
5
0
MOVZMBBl
848
10S8
351
230
N.R.
N.R.
230
351
230
351
N.R.
230
134
N.R.
N.R.
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
California Pip« Method.
N.R. "No Reading.
3-20
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Site Visit Report: Valdez Creek Mine
Table 3-3. NPDES Discharge Rates (continued)
DXT1
23
24
23
2«
27
21
21
30
30
SEPTEMBER
5
134
63
134
63
37
63
63
ocroBOt
0
0
0
M.R.
N.R.
N.R.
134
1058
494
MOTOBU
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
OUTLET FROZEN
3.3.3 Other Materials
In addition to mining wastes and materials, the facility generated wastes and materials from routine
operations that are not uniquely related to mining. These activities include equipment maintenance,
spill clean-up, etc. The facility operated a permitted landfill for disposal of solid waste generated
onsite. The main purpose of this landfill is to contain incinerator ash and residue and oil spill
material from routine activities at the site. The cell for oil spill material, which is to contain
approximately 3500 cubic yards of waste, was located on an old waste rock pile. The cell had a
single liner and a leak detection system installed below the liner. During the site visit, facility
personnel reported that the containment cell is being re-sealed as the original seams were not
sufficiently sealed. As of the date of EPA's site visit, no material had been disposed of in the lined
cell. Disposal was expected to begin once the seams have been effectively sealed. According to the
Solid Waste Permit Application, the landfill is located away from surface water and is over 200 feet
above the regional water table. (Valdez Creek Mining Company 1988) Additional construction
details and current usage were not obtained. The oil spill material was generated by previous
operators. According to facility personnel, prior to 1988, previous operators disposed of used oil by
dumping it into a pit for burning and tires were added to keep the flame burning.
The facility had two methods of trash disposal, a putrescible waste incinerator, and an "air curtain
burn box." The incinerator was used for disposal of domestic waste. (Valdez Creek Mining Company
1988) According to facility personnel, wood and other large debris are burned in the burn box. a
large steel container. Ash from these operations was disposed of in the landfill. (Valdez Creek
Mining Company 1988)
3-21
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Site Visit Report: Valdez Creek Mine
Waste oil was blended with diesel fuel and burned in waste oil furnaces. Wash water was directed to
a sump where a skimmer removes grease and oil, which are also burned in the waste oil furnaces.
Spent solvents from parts washing were also mixed with the waste oil and burned. The facility has a
State permit for the waste oil furnaces. The furnaces were made by Clean Energy Inc. and have a
500.(XX) BTU capacity. Approximately 8.800 gallons of used oil was generated and burned in June
of 1992
Antifreeze was recycled on site. The facility designed and constructed an antifreeze distillation unit in
order to recycle antifreeze. Because of the quantities of antifreeze used, and the difficulty and
expense of transporting antifreeze to such a remote site, the facility found recycling of the antifreeze
to be cost effective. The quantity of antifreeze recycled was not obtained.
Most of the facility's tires were hauled to a dump in Glenellen. Some tires are also used for lightpole
anchors. The facility stored scrap iron and steel, such as worn undercarriages, bucket teeth, chain,
plate steel, and pipe, in a forty foot hopper and sent it to a recycler in Anchorage. Approximately
120 tons per quarter is been recycled in this manner. Aluminum is also sent to a recycler at an
approximate rate of 20 cubic yards a quarter.
The facility operated two septic systems, one for the main site and one for campers. An additional
septic system is located at the Little Idaho camping area.
There are four 15,000 gallon diesel tanks and two 10,000 gallon diesel tanks on site, and this storage
area is lined and bermed. Other items stored onsite include antifreeze, solvents, gear lubricant,
ANFO, and propane. According to facility personnel, all tanks are above ground. Table 3-4
provides a list of tanks onsite.
3-22
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Site Visit Report: Valdez Creek Mine
Table 3-4. Storage Tank Summary
Tank Description
Gasoline Storage
Diesel Storage
Diesel Storage
Lubricant and Waste Oil
Storage
Miscellaneous Drum
Storage
Diesel Storage
Diesel Storage
Diesel Storage
Diesel Storage
Aviation Fuel Storage
Diesel Storage
Diesel/Lubricant
Storage
Location
Main Camp
Main Camp
Mam Generator
Installation
Cold Storage
Building
Maintenance Shops
Wash Plant
Generator
Sample Laboratory
Generator
Operations Staging
Area
ANFO Mix Truck
Airstrip
Pump Installation
Mobile Fueling
and Lubrication
Equipment
Contents
Unleaded Gasoline
No 1 Diesel
No. 1 Diesel
Motor Oil
Hydraulic Fluid
Ethylene Glycol
Transmission Fluid
Petroleum Naphtha
Grease
Waste Oil
Blending Tank
Blending Oil
Transmission Fluid
Petroleum
Naphtha
No. 1 Diesel
No. 1 Diesel
No. 1 Diesel
Transmission Fluid
Petroleum Naphtha
and Lubricants
No. 1 Diesel
Aviation Fuel
No. 1 Diesel
No. 1 Diesel Fuel/
Lubricants
Capacity
(Gal.)
6.000
15.000
500
3,000
3,000
1.000
3.000
3.000
550'
275,
400lbs
16,000*
6.000
10,000
220'
110'
1 •
500
250
15,000
15,000
15,000
27,50'
230
275
120s
3,000
1,300
Containment
(Gal.)
35.000
21.000
600
14.5003
Operating
Controls4
6,000
300
350,000
Operating
Controls4
Operating
Controls4
Factor of
Safety
5 8
1 4
1 2
1.3
N/A
120
1.2
23.3
N/A
N/A
Notes: ' Drum Storage (Capped 55 gallon drums on pallets).
1 Waste Oil Storage Tank active level is less than or equal to 2/3 capacity (10,700) gallons).
3 Containment capacity for Lubricant and Waste Oil Storage includes 5,000 gallons existing curb capacity, 7,000
gallon existing sump capacity, and 2,500 gallon proposed additional curb capacity.
4 Operating controls include temporary berms, regular inspections and specific operating practices as appropriate.
5 Fuel storage at any given pump installation does not exceed 120 gallons.
Source: Spill Prevention Control and Countermeasures Plan and Oil Discharge Prevention and
Contingency Plan, January, 1992.
3-23
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Site Visit Report: Valdez Creek Mine
3.4 REGULATORY REQUIREMENTS AND COMPLIANCE
The Valdez Creek Mine was subject to both State and Federal regulatory requirements and their
attendant permits. Because the operation is located on Federal land under the jurisdiction of the
Bureau of Land Management, the facility has prepared a Plan of Operations to satisfy BLM
requirements. The facility has an NPDES permit issued by the EPA Region X, as well as several
dredge and fill permits from the Army Corp of Engineers. State permits include dam safety and solid
waste disposal. The State of Alaska has an optional annual placer mining permit; according to facility
personnel, Cambior has not applied because the permit is optional. The State has no reclamation
requirements; however, BLM has requirements for reclamation with a schedule of acreage in the Plan
of Operations.
3.4.1 Federal Permits
3.4.1.1 Bureau of Land Management
Because the facility is located on Federal lands, BLM requires a Plan of Operations. BLM approved
the Valdez Creek Plan of Operations on June 19, 1990; the Plan is effective for five years.
Reclamation requirements include a schedule for reclamation of acreage, as specified in the Plan of
Operations. The Plan addresses smoothing of the pit walls, creek beds, old ponds and old roads.
The facility is working on areas U and V this year, and is using aerial seeding as a method as
hydroseeding has not worked well in the past (see Figure 3-2). The facility recontours slopes to 3:1
or shallower. Grass, clover and willow have been seeded. According to the facility, the total acreage
reclaimed in 1992 is approximately 180 acres; the facility plans to reclaim 135 new acres and 45 old
(previously reclaimed) acres each year. Specific details describing any problems that may arise with
reclamation, other than access to areas with the hydroseeding equipment, were not obtained.
According to facility personnel, immediate plans for reclamation include the A6 Pit this year (see
Figure 3-2).
3.4.1.2 Army Corp of Engineers
The facility has an Army Corp of Engineers CWA Section 404 permit for construction of the
diversion darn. It was issued on August 11, 1990 and expires in 1995. The Corps, has also issued
smaller permits for culverts and other smaller disturbances. These permits were not obtained.
3.4.1.3 Environmental Protection Agency
NPDES Permit
The Environmental Protection Agency's Region X Office has issued an NPDES permit to the facility.
The permit, number AK002497-0, was issued on July 10, 1989 and is effective for five years.
Effluent limitations set in the permit include: Turbidity 398 NTU's above background; settleable
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Site Visit Report: Valdez Creek
solids 0.2 ml/1; and total arsenic 0.05 mg/1. As discussed previously, discharge is from the Willow V
Ponds system through a pipe in Willow Creek dam. Table 3-3 shows discharge rates for a season.
Discharges may be exempt from the numeric limits if the facility qualifies for the "Storm exemption"
in part 1 D of the permit. They apparently availed themselves of this exemption three times from
December 1990 to November 1991, when storm events exceeded the 5-year 6-hour storm (the
quantity required to be stored to qualify for the storm exemption). The facility is required to monitor
their discharge once per season for arsenic and turbidity and once per day (during discharge) for
settleable solids.
According to a single sample taken (date of sampling not obtained), both turbidity and arsenic were
slightly above background levels but well below permit limits. In addition, there were three
exceedances of the settleable solids, two in May and one in August 1991. According to the facility,
these exceedances reflect natural events. (Cambior 1990) Additional compliance data was not
obtained.
Hazardous Waste
Cambior generates hazardous waste at the Valdez Creek mine in the laboratory and is considered a
conditionally exempt small quantity generator. The waste, mercuric nitrate, is generated in a solution
from washing of the amalgam bead used in analysis of drill cores in the lab. The SIC code is 1041.
The facility has a generator ID Number, AKD982656761.
3.4.2 State Permits
3.4.2.1 Dam Safety
The facility has State Dam Safety Permits, which are divided into 3 sections: the settling ponds (also
called Willow Creek ponds); the diversion dam (also called the Aspen 4 Dam); and the sluice ponds.
There are 5 Willow Creek Ponds, each is approximately 10 acres each. They were constructed of
native compacted soils with no liner or grout and have decants and spillways.
The diversion dam, as described previously, is approximately 200 feet wide and over 25 feet tall with
a crest width of approximately 50 feet. The area impounded during breakup is two to three times the
normal impoundment size of 25 acres and reaches a maximum of approximately 100 acres.
Typically, the water is only a few feet deep; but at breakup it may reach 10 feet in depth. The
diversion ditch leads approximately 5,000 feet downhill, from the diversion dam to the point where it
discharges to the creek. The diversion ditch is lined with a synthetic liner and rip-rap to prevent
erosion and downcutting.
The sluice ponds are actually old mining pits A4 and A5 and are called the E4 and E5 wash plant
ponds. There are actually three ponds in this system, each approximately five acres in size with the
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Site Visit Report: VaMez Creek Mine
deepest being 20 feet and the others ranging from five to 10 feet deep. The dam between the first
and second ponds is lined with a synthetic liner due to seepage problems. The ponds are used to
recycle water from the wash plant. Tailings are discharged from the wash plant into the primary
settling pond, which discharges to the secondary settling pond and then to the tertiary settling pond,
where water is reclaimed and pumped back to the wash plant. Cambior has had several problems
with pond 2. which has failed twice. At the time of the site visit, the dam had been reconstructed and
lined and Cambior was refilling the pond with water to test its integrity. Cambior expects a final
permit for this pond when the construction is finished.
3 4.2.2 Diversion Channel
On November 2, 1992, the Alaska Department of Environmental Conservation issued a Certificate of
Reasonable Assurance, in accordance with Section 401 of the Clean Water Act of 1977, for the
placement of fill material into wetland areas. Approximately 30,229,400 cubic yards of fill will be
discharged into 317 acres of waters of the U.S. (wetlands) for the construction of the 4800 foot long
Stage II lined diversion channel. The existing one mile long Stage I diversion channel has been
designated, by this Department, as a mixing zone for the flushing of the new lined channel. As a
condition of the Department's issuance of the Certificate of Reasonable Assurance, Cambior is
required to have a third party conduct water quality monitoring, for turbidity and settleable solids,
during the actual flushing of the new channel.
3.4.2.3 Alaska Fish and Game
Alaska Fish and Game has issued a permit to move fish from below the facility to above the diversion
dam during spawning. Cambior has retained the services of Potterville Specialties Service and
Northern Alaska Fisheries Services to move the fish each year. The activities take place several days
each week over a period of about a month and a half in the spring. According to Cambior personnel,
the facility appears to be dealing with two distinct fish populations.
3.4.2.4 Solid Waste Permit
The facility has permits for two landfills, a putrescible waste incinerator, and an "air curtain burn
box." (Valdez Creek Company 1990). According to facility personnel, the facility also has a permit
to operate used oil furnaces; this permit was not obtained during EPA's site visit. According to
facility personnel, oil filters are no longer burned in the burn box as specified in the permit by
direction of a DEC inspector.
According to the Alaska Department of Environmental Conservation (DEC), the facility has one Solid
Waste Disposal Permit, which expires in November 1993. The permit allows for the seasonal
disposal of oily soil, incinerated camp waste, and non-combustible residue into lined containment cells
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at the mine site. There is no limit as to the number of individual cells that can be developed under
this permit
Used oil filters were previously being burned in the burn box. State regulations concerning open
burning, prohibit the burning of oily wastes or other materials that give off black smoke, without
written permission from the Department. Due to a potential air quality violation, Cambior personnel
were instructed by a Department inspector to dispose of used oil filters in the lined containment cells.
Currently, new State Solid Waste Management Regulations are being developed in preparation of the
new EPA Solid Waste Regulations that will become effective no later than October 1993. At this
time, it is uncertain how these new regulations will affect the renewal of Cambior's solid waste
disposal permit.
3.4.3 Inspections and Compliance Incidents
3.4.3.1 Inspections
Department of Environmental Conservation
According to Cambior personnel, DEC inspects the facility once per year to review waste
management, including the incinerator and burn box, the septic system, trash and other solid waste
disposal, as well as water quality. According to the Alaska DEC, there were three inspections during
1991 and one inspection in 1992 (as of November 1992). The most recent unannounced inspection
occurred approximately three weeks prior to EPA's site visit. According to Cambior, the inspector
verbally noted erosion on the side of the diversion channel caused by breakup but did not send a
report to the facility in writing. According to Cambior, the State typically does not send inspection
reports to the facility unless there is a serious problem.
The Little Idaho campground is located on land within the claim block that Cambior Ak leases from
BLM. Little Idaho is not a public campground and is restricted by Cambior to employee use only.
The drinking water and wastewater disposal systems at the camp serve a bath/toilet house and RV
dump station available to campers. There are no individual water or sewer hookups to the camping
spaces. The campground is used seasonally during summer months only.
Construction approval, for both water and sewer systems, was issued by this Department in the
Summer of 1992. The sewer system, after construction, was put into use by Cambior without a final
operating approval from this Department. A 30-day interim operational approval was issued for the
water system only, which expired September 6, 1992. Final operational approvals for these systems
have not yet been issued, and are pending submittal and approval of engineers as-builts of the
installed sewer system and satisfactory water sample analysis results on the water system.
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Site Visit Report: Valdez Creek Mine
Bureau of Land Management
Representatives from the BLM visited the site one week prior to EPA's site visit. BLM voiced
concern about uncontrolled camping. Little Idaho is a permitted camping area for employees
provided by Cambior. The BLM expressed concern over camping outside of designated areas by
others visiting the area. The number of visitors increases especially during hunting season.
According to Cambior personnel. Little Idaho is outside of the active mining area on public land.
Mine Safety and Health Administration
*
The Mine Safety and Health Administration inspects the facility twice a year. The most recent
inspection prior to EPA's site visit was in March of 1992. There were a number of violations cited
with the most serious addressing a ladder in a culvert with no safety loops and "dumpover," where a
truck backs to the very edge of a pit and dumps its load. The preferred method is to dump and then
use a dozer to push material to the edge of the pit. Noise and dust at the washer plant, and at drills
and dozers were also reviewed with no citations issued. The fines for this inspection totalled
approximately $600.
3.4.3.2 Compliance Incidents
Waste Oil
According to facility personnel, an oil spill was identified in the area surrounding the generator shack.
The facility attributed the release to drips over several years of operation. Approximately 75 cubic
yards of contaminated soil were excavated and will be disposed on site in a containment cell permitted
by the State. According to facility personnel, prior to 1988, previous operators disposed of used oil
by dumping it into a pit for burning and tires were added to keep the flame burning. According to
Alaska DEC, some, but not all, of the contaminated soil has been excavated and disposed of in a
containment cell covered by the Solid Waste Disposal Permit. In addition, in 1991, extensive oil spill
contamination was discovered in an outside area known as the "dead line," which is used for heavy
equipment storage and repairs. The Department required that a third party consultant conduct a sue
assessment and corrective action plan for these two contaminated areas. To date, these two
contamination issues are still unresolved.
During this Department's June 1992 inspection, it was noted that Cambior had improved maintenance
practices and preventative procedures to help prevent soil contamination. Small quantity releases
occur fairly often at the mine site from such things as equipment hydraulic line breakage, and outside
equipment maintenance, including oil and fluid changes, and leakage of fluids from equipment
awaiting repairs.
A contaminated waste management plan, submitted by Cambior on September 9, 1992 was found to
be unacceptable to the Department. The plan included a spring cleanup of contamination occurring
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during the winter months, periodic cleanup during the summer months, and "reportable" spills to be
cleaned up immediately. The plan did not include how a determination would be made to insure
adequate cleanup or how appropriate minimum target cleanup levels would be met. State regulations
require aH spills to be cleaned up immediately. Cambior is revising their waste management plan to
meet state regulations and the concerns of the Department.
Fuel Spill
According to facility personnel, approximately three to four years ago a truck dumped fuel on the
ground. No additional details concerning this spill were obtained.
i
Dam Failure
October 27, 1991, the first pond of the three sluice ponds used by the facility failed and released
approximately 50 million gallons of tailings water into Valdez Creek. As required by the Alaska
DEC. the facility conducted TCLP testing on the sediments and found no toxic contamination. The
Department further required the deposited sediments to be pulled back from the creek to prevent
spring breakup high water flows from eroding the sediments and creating a water quality violation of
turbidity and settleable solids. Stabilization of the slope, and silt fences to protect the quality of the
creek, were also required by the Department. During the actual releases, it is highly suspected that
water quality standards were drastically exceeded downstream within Valdez Creek. On May 25,
1992, the same pond failed during testing and approximately 15 million gallons of water were
released into the creek. At the time of the site visit, the dam had been reconstructed, with a liner and
piezometers, and facility personnel were preparing to fill and retest it. No other details on these
failures were obtained. It is unclear whether the releases of water caused exceedance of arsenic and
other water quality standards downstream on Valdez Creek. According to the DEC, water quality
monitoring was not conducted by Cambior during the two dam failure events.
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3.5 REFERENCES
Bureau of Land Management. Denali Mine, 1990 - 1994 Environmental Assessment. Prepared for
BLM by Environmental Services, Ltd., May 1990.
Bureau of Land Management. Letter from Gene Keith, District Manager, to Paul Martin, VCMC,
approving the updated 5-year Plan of Operations and Environmental Assessment. June 29,
1990
Cambior Alaska. Letter from Douglas Nicholson, Chief Engineer, Cambior Alaska, Inc. to Director,
Waster Division, Region X U.S. EPA, concerning Discharge Monitoring Reports for NPDES
permit AK-002497-0, for the period 12/10/90 through 11/30/91. November 29, 1991
Cambior Alaska, Inc. Spill Prevention, Control and Countermeasures Plan (SPCC Plan) and Oil
Discharge Prevention and Contingency Plan, prepared for Cambior by ACZ Inc. Steamboat
Springs CO. (Only portions obtained). January 1992.
Cambior Alaska. Inc. 1991 Hazardous Waste Report, EPA Form 1C, Identification and Certification.
EPA ID No. AKD-982-656-761, February 28, 1992.
Department of the Army, Army Corp of Engineers. Permit Number 4-890170 permit modification
notification, Valdez Creek 1. August 21, 1990.
State of Alaska. State vs. Valdez Creek Mining Company, Inc. Case No. 3PA-S88-315 Cr. Dated
June 1988. WHEREAS there was some pollution .... Undated.
State of Alaska. Dam Safety Certificate of Approvals for Willow Creek 5 dam and A4 pond system,
March 25, 1992.
State of Alaska, Department of Natural Resources. Letter from Kyle Cherry to Assistant General
Manager, VCMC, approving continued operation of the Aspen 4 dam. January 23, 1992.
State of Alaska, Department of Environmental Conservation. Letter from Henry Friedman to
Environmental Services, Ltd. concerning the draft solid waste permit for Valdez Creek Mine.
December 1, 1988.
State of Alaska, Department of Environmental Conservation. Letter from Bill Lamoreaux to Richard
Hughes, VCMC, issuing permit # 8822-BA004. December 21, 1988.
Valdez Creek Mining Company. Solid Waste Management Permit Application for the Denali Mine.
prepared for VCMC by Environmental Services, Ltd. (Only portions obtained). July 1988.
Valdez Creek Mining Company, 1989 - 1993 Plan of Operations, Denali Mine, prepared for VCMC
by Environmental Services, Ltd. (Only portions obtained). August 30, 1989
U.S. Environmental Protection Agency. NPDES Permit AK-002497-0 for Valdez Creek Mining
Company. Effective 8/09/89 through 8/08/94.
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APPENDIX 3-A
COMMENTS SUBMITTED BY CAMBIOR ALASKA INC.,
ON DRAFT SITE VISIT REPORT
The letter reproduced in this appendix accompanied a copy of the draft site visit report on which
Cambior Alaska Inc., had made comments and corrections. A copy of the marked-up draft is not
reproduced here for brevity's sake. In general, Cambior's comments were clarifying in nature,
providing information that the draft repon indicated had not been obtained during the site visit or
correcting minor factual errors in the draft. EPA's response to Cambior's comments are provided in
Appendix B.
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APPENDIX 3-B
EPA RESPONSE TO COMMENTS SUBMITTED BY
CAMBIOR ALASKA INCORPORATED
ON DRAFT SITE VISIT REPORT
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EPA Response to Comments Submitted by
Cambior Alaska Incorporated
on Draft Site Visit Report
EPA has revised the report to incorporate all of the comments and suggestions made by Cambior
Alaska Incorporated. In some cases, EPA made minor changes to wording suggested by Cambior in
order to attribute the changes to Cambior or to enhance clarity.
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APPENDIX 3-C
COMMENTS SUBMITTED BY THE STATE OF ALASKA
ON DRAFT SITE VISIT REPORT
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APPENDIX 3-D
EPA RESPONSE TO COMMENTS SUBMITTED BY
THE STATE OF ALASKA
ON DRAFT SITE VISIT REPORT
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EPA Response to Comments Submitted by
The State of Alaska
On Draft Site Visit Report
EPA has revised the report to incorporate all of the comments and suggestions made by the State of
Alaska. In some cases, EPA made minor changes to wording suggested by the State.
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