EPA 530-R-94-034
NTIS PB94-201001
TECHNICAL RESOURCE DOCUMENT
EXTRACTION AND BENEFICIATION OF
ORES AND MINERALS
VOLUME 7
PHOSPHATE AND MOLYBDENUM
November 1994
U.S. Environmental Protection Agency
Office of Solid Waste
Special Waste Branch
401 M Street, SW
Washington, DC 20460
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DISCLAIMER AND ACKNOWLEDGEMENTS
This document was prepared by the U.S. Environmental Protection Agency. 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 reports on two site visits conducted by EPA to a
phosphate mine in Florida and a molybdenum mine in Idaho during 1991 and 1992. Drafts were
distributed for review to representatives of the companies and of state agencies who participated in the
site visits, as well as the U.S. Department of Interior's Bureau of Mines and the U.S. Department of
Agriculture's Forest Service. Their comments and EPA's responses are presented as appendices to
the reports. EPA is grateful to all individuals who took the time to review sections of this Technical
Resource Document.
The use of the terms "extraction," "beneficiation," and "mineral processing" in this document is not
intended to classify any waste stream for the purposes of regulatory interpretation or application.
Rather, these terms are used in the context of common industry terminology.
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MINE SITE VISIT:
IMC FOUR CORNERS MINE
March 1993
U.S. Environmental Protection Agency
Office of Solid Waste
401 M Street, SW
Washington, DC 20460
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Site Visit Report: IMC Four Corners
DISCLAIMER AND ACKNOWLEDGEMENTS
This document was prepared by the U.S. Environmental Protection
Agency. The mention of company or product names is not to be
considered an endorsement by the U.S. Government or by EPA.
This section of the Technical Resource Document consists of a report
on a site visit conducted by EPA to IMC Fertilizer, Inc. Four Corners
Phosphate Mine in Florida during 1992. A draft of the report was
provided to representatives of IMC Fertilizer, Inc., and the Florida
Department of Natural Resources who participated in the site visit.
IMC submitted comments on the draft, which are presented in
Appendix B. EPA's responses to IMC's comments are summarized in
Appendix C.
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Site Visit Report: IMC Four Corners
TABLE OF CONTENTS
1. INTRODUCTION 1
1.1 Background 1
1.2 General Facility Description 2
1.3 Environmental Setting 5
1.3.1 Climate ; 5
1.3.2 Surface Water 5
1.3.3 Geology 7
1.3.4 Hydrogeology 7
1.3.5 Wildlife . 10
2. FACILITY OPERATIONS 11
2.1 Mining Operations 11
2.2 Beneficiation Operations 13
2.2.1 Washing Plant 13
2.2.2 Heavy Media Separation Plant 15
2.2.3 Flotation Plant 18
2.3 Associated Operations 20
3. WASTE AND MATERIALS MANAGEMENT 22
3.1 Clay Ponds and Water Management 22
3.2 Tailings 26
3.3 Debris 27
3.4 Runoff 28
3.5 Mine Water 28
3.6 Other Wastes and Materials 28
3.6.1 Waste Oil 28
3.6.2 Steel Pipe 29
3.6.3 Dragline Grease 29
3.6.4 Spent Solvents 29
3.6.5 Laboratory Wastes 29
3.6.6 Tires and Batteries 30
3.6.7 PCBs '..'.'.'.'. 30
3.6.8 Trash 30
3.6.9 Sanitary Wastewater and Sewage Sludge 30
4. REGULATORY REQUIREMENTS AND COMPLIANCE 31
4.1 Operational Requirements and Permits 31
4.1.1 Development of Regional Impact Studies and County Development
Orders 31
4.1.2 State Reclamation Requirements 35
4.2 Ground Water 35
4.2.1 State Ground-water Protection Requirements 35
4.2.2 Summary of Ground-water Monitoring and Use at Four rners 37
4.3 Surface Water 38
4.3.1 NPDES Permit 38
4.3.2 State Surface Water Discharge Permit 40
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Site Visit Report: IMC Four Corners
TABLE OF CONTENTS
(continued)
4.4 Air 42
4.5 Water Use Permit 42
4.6 Other Permits 43
4.6.1 Wastewater Treatment Plant Operating Permit 43
4.6.2 Wetlands Permits 45
4.6.3 Tank Permits 45
4.6.4 Domestic Water Supply Permit 46
REFERENCES 48
APPENDICES
APPENDIX A 1991 Ground-Water Monitoring Data
APPENDIX B Comments Submitted by IMC Fertilizer, Inc., on Draft Site Visit Report
APPENDIX C EPA Response to Comments submitted by IMC Fertilizer, Inc., on Draft Site Visit
Report
LIST OF FIGURES
Figure . Page
1 Map of Phosphate Mining Region of Florida 3
2 IMC Four Comer Site Map 4
3 Surface Waters in the Vicinity of IMC Four Corners Mine 6
4 Geology and Hydrogeology at the Four Corners Site 8
5 Washer Plant Flow Diagram 14
6 Flotation Plant Flow Diagram 18
7 IMC Four Corners Water Balance 25
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Site Visit Report: IMC Four Corners
LIST OF TABLES
Table Page
1 Summary of Flotation Reagent Use at Four Corners 17
2 Summary of Waste & Materials Generation and Management at Four Corners 24
3 Summary of 1991 Surface Water Monitoring 33
4 NPDES Permit Requirements for Outfall 001 39
5 Summary of Monitoring Data for Outfall 001 (9/90 - 12/91) 41
6 Ground-water Withdrawal Rates for IMC Four Corners 44
7 Effluent Limits and Monitoring Requirements for the Discharge from IMC's
Wastewater Treatment Plant 45
8 Summary of Wetlands Permits for IMC Four Corners Mine 46
IV
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Site Visit Report: IMC Four Corners
1. INTRODUCTION
1.1 Background
EPA has initiated several information gathering activities to characterize mining wastes and waste
management practices. As part of these ongoing efforts, EPA is gathering data by conducting visits
to mine sites to study waste generation and management practices. As one of several site visits, EPA
visited IMC Fertilizer, Inc.'s Four Corners Phosphate Mine near Duette, Florida on March 18, 1992.
This report discusses the extraction and beneficiation activities at the site. No discussion of
phosphoric acid production is found in this report.
The sites to be visited were selected by EPA to represent both an array of mining industry sectors and
different regional geographies. All site visits are conducted pursuant to the Resource Conservation
and Recovery Act (RCRA), Sections 3001 and 3007 information collection authorities. For those
sites located on Federal land, EPA has invited representatives of the appropriate land management
agency (U.S. Forest Service and Bureau of Land Management). State agency representatives and
EPA regional personnel also have been invited to participate in each site visit.
For each site, EPA has collected waste generation and management information using a three-step
approach: (1) contacting the facility by telephone to obtain initial information, (2) contacting state
regulatory agencies by telephone to obtain additional information, and (3) conducting the actual site
visit. Information collected prior to each visit is then reviewed and confirmed at the site.
The site visit reports describe mine operations, mine waste generation and management practices, and
the regulatory status on a site-specific basis; the information is based on information gathered from
State and Federal agency files as well as observations made during the site visit. In preparing this
report, EPA collected information from a variety of sources, including IMC Fertilizer, Inc., the
Florida Department of Natural Resources (DNR), and other published information. The following
individuals participated in the IMC Four Corners site visit on March 18, 1992.
IMC Fertilizer. Inc.
Jim Burleson, Vice President and General Manager (813) 533-1121
Ronald Wiegel, Technical Manager (813) 533-1121
Jay Allen, Environmental and Permitting Manager (813) 533-1121
IMC Fertilizer. Inc. (continued)
Lee Turner, Manager of Engineering and Production Services (813) 533-1121
Gene Armbrister, Production Manager for Four Corners (813) 533-1121
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Site Visit Report: IMC Four Corners
Florida Department of Natural Resources
Joe Bakker, Director, Resource Management Division
U.S. Environmental Protection Agency
Steve Hoffman, Mining Waste Section Chief
Science Applications International Corporation
(904)488-1254
(703) 308-8413
Ron Rimelman, Chemical Engineer
(703) 821-4861
1.2 General Facility Description
IMC Fertilizer, Inc. (IMC) operates a phosphate mine and mill located along State Road 37 in West
Central Florida, approximately five miles from Duette, Florida. The facility is comprised of
approximately 20,000 acres in Hillsborough and Manatee Counties. According to IMC, several plots
of land owned by other parties (identified by IMC as "out parcels") are found within the boundaries
of the Four Comers operation. Figure 1 presents a map of the phosphate mining region of West
Central Florida and Figure 2 presents a site map for the Four Corners Mine.
Prior to construction of the current operation at IMC, significant historic mining occurred within the
site boundaries and in the surrounding area. The Four Corners Mine was originally an equal
partnership between IMC and W.R. Grace Corporation. Construction at the site was initially
completed in 1983 and operations began in late 1985. The mine operated continuously for 13 months
until March 1986, when unfavorable market conditions prompted closure of the facility. In January
1988, the entire operation was acquired by IMC. In January 1989, IMC restarted operations and the
facility has operated continuously since then.
Four Corners is IMC's largest operation, with a total reserve of 185 million tons of ore. The
maximum capacity of the operation is 7.8 million tons of ore per year. The projected life of the mine
is 25-30 additional years from the time the site visit was conducted. The mine operates 5 days per
week, 250-260 days per year, with three shifts per day, and produces 5.5 million tons of ore per
year. Four Corners has approximately 300 employees.
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Site Visit Report: IMC Four Corners
Figure 1. Map of Phosphate Mining Region of Florida
(Source: U.S. EPA Field Notes)
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Site Visit Report: IMC Four Corners
Figure 2. IMC Four Corner Site Map
(Source: U.S. EPA Field Notes)
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Site Visit Report: IMC Four Corners
The Four Corners operation consists of concurrent mining in four separate areas. Draglines remove
ore from these areas, water is added, and slurried ore is piped to a washer plant for initial sizing.
The washer plant yields a pebble phosphate product and fine flotation feed. The pebble product is
tested to determine the concentration of magnesium oxide (MgO). If the MgO concentration is less
than one percent, it is considered a product and no further beneficiation is required. If the MgO
concentration exceeds one percent, the ore is directed to a patented heavy media separation plant for
MgO removal.
The flotation feed is sent to the flotation plant, where the ore is passed through hydraulic sizing and
over screens and separated into three sizes. Different flotation methods are used for each size
material. The flotation products are then combined with the pebble product and shipped off-site to
IMC's New Wales phosphoric acid plant and to other customers.
The washer plant generates oversized debris and undersized clays, which are considered wastes and
managed on-site. The flotation plant generates tailings, which are stored in on-site tailings piles
before being used as backfill for reclamation and in clay pond construction.
1.3 Environmental Setting
1.3.1 Climate
Between September 1978 and December 1991, the monthly total rainfall ranged from 0 inches
(November 1991) to 14.5 inches (September 1979) with the highest rainfall totals typically occurring
during the summer months. The total rainfall in 1991 was 39 inches, with an average monthly
rainfall of 3.75 inches (IMC, 1992a). Although no information concerning temperatures was
available for the Four Corners area, the 1991 mean temperature in Bartow, Florida, a town less than
30 miles from the site, was 72.2°F. In 1991, the highest average monthly temperature (90°F)
occurred in June and July and the lowest average monthly temperature (54°) occured in February and
November. No information was obtained on wind conditions at the site.
1.3.2 Surface Water
The surface waters in the vicinity of the Four Corners Mine Site are shown in Figure 3. The Little
Manatee River begins approximately three miles north of the mill site. Alderman Creek, a tributary
of the Little Manatee begins near the facility's clay ponds and receives discharges from IMC's Clay
Pond Fl through NPDES permitted outfall 001. Horse Creek and Payne Creek, a tributary of the
Peace River, also flow through sections of IMC's property. According to IMC personnel, runoff
from most of the site (not including the beneficiation plant) flows into Alderman Creek, Horse Creek,
Payne Creek, and the Little Manatee River. In addition, the South Fork of the Little Manatee River
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Site Visit Report: IMC Four Corners
Figure 3. Surface Waters in the Vicinity of IMC Four Corners Mine
(Source: U.S. EPA Field Notes)
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Site Visit Report: IMC Four Corners
and its tributary Long Branch, and the North Fork of the Manatee River, begin approximately 3-5
miles southwest of the plant site. As described in Section 4.6.2, mining and post-mining reclamation
activities are being conducted in the wetlands found in these drainage areas. IMC is required by the
State to restore wetlands disturbed by mining.
Surface waters in the vicinity of the site are characterized as clear, dark (from tannic acid), and
slightly acidic. Flow rates are generally high between July and September, when heavy
thunderstorms are common. Low flows typically occur from January through May. All surface
waters are designated by the State as Class HI fresh waters. Class HI fresh waters are protected for
recreation uses and for the propagation and maintenance of a healthy, well-balanced population of fish
and wildlife. According to IMC, the primary uses of the surface waters in the vicinity of the site are
recreational.
1.3.3 Geology
The IMC site is characterized by shallow phosphate deposits interbedded with sand and clay. As
shown in Figure 4, from the surface down, the site consists of (1) a thin layer of topsoils, (2) an
upper layer of sand, (3) an unconsolidated layer identified as the "leach zone," (4) a zone of
phosphate, clay, and sand (from which matrix ore is mined), (5) bed clay, and (6) limestone.
The upper two layers (the sand layer and the leach zone) represent overburden material. The leach
zone is not found in all areas. Where the leach zone occurs, the average thickness is two feet. The
leach zone is completely unconsolidated and consists of coarse phosphate pebbles and aluminum
phosphate. The combined depth of the sand layer and the leach zone averages 26 feet. The matrix
ore zone extends from approximately 26 feet below the surface to 46 feet below the surface. Within
this zone, there are two layers of ore separated by a layer of limestone. IMC is currently mining the
lower ore layer.
1.3.4 Hydrogeology
The Central Florida Phosphate district, including the Four Corners Mine Site, can be characterized by
three hydrostratigraphic horizons. These are: (1) the surficial aquifer system (1-20 feet deep), (2)
the intermediate Hawthorn aquifer (100-200 feet deep, below the limestone) and the deep Floridian
aquifer (below 400 feet deep). Each of the three aquifers is separated from the other aquifers by bed
clay (FIPR, 1991). All ground water underlying the Four Corners site is classified by the State as G-
II, potential drinking water supplies with a total dissolved solids level of less than 10,000 parts per
million (ppm).
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Site Visit Report: IMC Four Corners
Figure 4. Geology and Hydrogeology at the Four Corners Site
(Source: FIPR, 1991)
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Water Table
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»H«-»1«i*i«e«it* Send Jl Q
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Site Visit Report: IMC Four Corners
According the IMC staff, the ground-water table in the vicinity of the Four Corners mines ranges
from one to three feet below the ground surface. The surficial aquifer contains clean quartz sand and
clayey sand, both of eolian and marine origins. The ages of these deposits vary from Plio-Pleistocene
to Recent. Organic and Ferruginous B horizons as well as hardpans are locally present. The aquifer
is unconsolidated and tends to slump when saturated (FIPR, 1991).
Surficial aquifer water is acidic, reducing, and organic rich. It is seldom used as a public drinking
water supply, but it is used for low-yield domestic wells (FIPR, 1991). According to IMC personnel,
private (i.e., low-yield domestic) drinking water wells are located in the surficial aquifer less than 1/4
mile from the site boundaries. In addition, surficial aquifer wells in the vicinity of Four Corners are
used for agricultural water.
Where present, the leach zone forms the base of the surficial aquifer, and can introduce high levels of
radioactivity, fluorides, and other unwanted constituents. The leach zone is a discontinuous
weathering profile developed on top of the underlying phosphoric material of the Hawthorn group. It
is enriched with aluminum phosphate materials such as wavellite and crandallite, and in uranium and
uranium daughters. Some linear circular thickening patterns appear to be related to the development
of alluvial dolines and fractures (FIPR, 1991).
The intermediate (Hawthorn) aquifer and the confining Arcadian Formation (Miocene to Pliocene
Age) are phosphatic, have extensive clastic horizons, and are characterized by dolostone and
limestone. There are also varying degrees of cavernous porosity. The Hawthorn aquifer exhibits
typical carbonate-aquifer chemistry, with calcium, magnesium, bicarbonate, and sulfate/sulfide
elements present. In the intermediate aquifer fluoride may be slightly elevated and radium-226 may
be present near the maximum contaminant level (MCL) of five picocuries per liter (pCi/1) (FIPR,
1991). This intermediate aquifer is the primary source of drinking water for private wells in the
vicinity of the Four Corners site.
The Floridian aquifer is one of most productive aquifers in the world. It includes limestone, with
minor dolostone and clastic strata of Miocene to Eocene Age. The aquifer is primarily a fractured
and karstic aquifer with, to a lesser extent, intergranular and moldic porosity. The Floridian aquifer
is confined and artesian. The aquifer is neutral to slightly alkaline, containing high levels of calcium
and magnesium (FIPR, 1991). Bicarbonate sulfate is the dominant sulfur species with levels up to
1,500 ppm having been detected (Palm & Associates, 1983a). To obtain water for domestic uses
(including drinking water), the facility draws from well PTW-3 completed in the Floridian aquifer.
In May 1991, the Florida Institute of Phosphate Research published Radiochemistry of Uranium-series
Isotopes in Groundwater. This study of ground water in the phosphate mining region showed that
radium levels in the Floridian aquifer do not pose environmental or human health risks. Lead and
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Sire Visit Report: IMC Four Corners
ypolonium were found in the surficial aquifer (and presumably, would also be found in pumped mine
water) at elevated levels (FIPR, 1991).
1.3.5 Wildlife
The EPA site visit team observed abundant wildlife (including many birds and an American alligator),
particularly around the clay ponds. According to IMC personnel, bald eagles nest in Manatee
County. In addition, the American alligator is a threatened species (as identified by the U.S. Fish and
Wildlife Service). No other rare or endangered species are found in the vicinity of the Four Corner
site.
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Site Visit Report: IMC Four Corners
2. FACILITY OPERATIONS
Surface mining is currently conducted in four areas at Four Corners. Matrix ore is transported by
pipeline to the beneficiation operation. In the beneficiation operation, matrix ore is initially sent to
the washer plant, where pebble and flotation feed are separated from clay and debris (coarse oversize)
wastes. As necessary, the pebble product undergoes heavy media separation to remove magnesium
oxide. The flotation feed is sent to the flotation plant. The following sections describe mining and
beneficiation at Four Corners, along with associated operations at the site.
2.1 Mining Operations
The Four Corners site consists of 17,567 minable acres; 2,599 acres have been mined to date. IMC
has four draglines, located in four separate areas at the site (see Figure 2). Active mining operations
are conducted in each of these areas. Mining consists of clearing the'site of brush, initial removal of
topsoil and overburden, matrix ore removal, and reclamation. As mining is completed, the dragline
moves to a new location in the area. Typically, two draglines strip overburden and topsoil, while the
other two draglines remove matrix ore to allow for maximum use of mill capacity. Two of IMC's
draglines have 65 cubic yard buckets and two draglines have 43 cubic yard buckets.
Brush is initially removed from areas to be mined. A dragline then moves into the area and removes
overburden and a thin layer of topsoil, which together extend to a depth of about 26 feet. The topsoil
is generally similar to the sand overburden, except in wetlands areas, where it contains some organic
material. Overburden and topsoil are placed in temporary piles for subsequent use in reclamation
and/or dam construction. (The piles were not observed by the EPA site visit team.) For every 11
tons of material moved, 6.5 tons of overburden and topsoil and 4.5 tons of matrix ore are sent to the
plant. After the overburden and topsoil have been removed, the draglines excavate the matrix ore and
place it in "wells." These wells are essentially 50-foot diameter excavations that are 10-15 feet deep.
IMC's draglines each have the capacity to place up to 3,000 cubic yards of ore per hour into the
wells.
In the wells, a slurry of 45-45 percent solids is created by high pressure water sprayed from hydraulic
monitors. The source of the water is IMC's recirculation system (see Section 3.1). The 1,600
horsepower electric hydraulic monitors operate at 250 pounds per square inch (psi). The water is
pumped at a rate of 10-12,000 gallons per minute (gpm). At each well, IMC typically uses two
monitors, identified as the "left trap gun" and the "right drift gun." The "right drift gun" is used to
move the matrix ore toward a 24-inch diameter suction pump. "Grizzlies" (described by IMC as
stationary screens) are placed in front of the suction pumps to keep them clear of large sized ore
(greater than 9-inch diameter, the nominal capacity of the pumps). The "left trap gun" is used to
keep the grizzly clean.
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Site Visit Report: IMC Four Corners
IMC's mining operations at Fours Corners are typical of those found at other phosphate mines.
However, the ore body at Four Corners is particularly lean. For every 4.5 tons of matrix material
sent to the mill, one ton of product is generated. Therefore, IMC generally uses larger systems and
equipment, and their pit pumps operate at much higher rates than other facilities.
The monitors and pumps are mounted on "pit cars." Fresh water is pumped to the pit cars through
24-inch steel pipes from IMC's fresh water management system (i.e., the clay ponds). The total
retention time of matrix ore in each well ranges from a few seconds to an hour. Slurried ore is
removed at a rate of 1,800-2,000 gpm.
Matrix ore is then pumped from the mine site to the mill (washer) in unlined abrasion-resistant steel
pipe (22 inch diameter and 3/8 inch thick). Due to the coarseness of the matrix ore, IMC personnel
indicated that plastic piping cannot be used (plastic piping is used at the site for tailings transport, see
Section 3.2). Pipeline is laid directly on the ground surface with no secondary containment. Ditches
and berms are utilized selectively as required to prevent the off-site drainage of slurried ore to
adjacent wetlands or stream systems due to gasket failures, pipeline breaks, etc. This precautionary
approach is used only when the potential for off-site drainage exists which might have an impact on
ecologically sensitive areas. Along the matrix ore pipelines, there are in-line electric lift pumps every
4,000 feet. IMC currently has 22 older single speed electric pumps and 6 new DC drive, variable
speed pumps. Each pump has an automatic shutoff switch that stops pumping if low pressure is
encountered (i.e., a leak occurs or a pipeline becomes plugged). According to IMC personnel, the
pumps are checked for leakage daily and leakage of matrix ore into the purnp oil is more common
than leakage of oil out of the pumps. Frequently, the slope from active mining areas to the
beneficiation plant (currently from one to three miles) are such that one matrix pipeline has nine lift
pumps.
To even out wear, the matrix pipe is rolled 120 degrees every 6 to 8 months of operation. Because
the coarseness of the rock provides natural scouring, IMC does not need to pig the matrix pipes.
When a pipe is no longer usable for matrix ore transport, it is reclaimed for use in other areas of the
facility (e.g., for fresh water transport). Ultimately, when all on-site uses of the piping have been
exhausted, it is sold as scrap. (For more information on pipe recycling, refer to U.S. EPA, Office of
Solid Waste (1994). Innovative Methods of Managing Environmental Releases at Mine Sites.)
After mining is completed hi an area, the dragline moves to a new location and IMC begins
reclamation activities. Mining areas are reclaimed with removed overburden, topsoil, and mill
tailings. They are then revegetated and reforested in accordance with IMC's reclamation plan and
State reclamation rules (see Section 4.1). The entire cycle, from pre-mining activities through
reclamation, requires approximately two years.
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Site Visit Report: IMC Four Corners
2.2 Beneficiation Operations
The matrix ore pipelines flow to the beneficiation plant at Four Corners. The raw matrix ore consists
of materials of varied sizes up to nine inch diameter rock. IMC uses separate beneficiation methods
for different size fractions of ore. While beneficiation methods (except the patented heavy media
separation plant) are similar to those used at other phosphate operations, the degree to which the
specific methods are tailored to material size is unique to Four Corners.
Beneficiation occurs in three separate plants: (1) the washing plant, (2) the heavy media separation
plant, and (3) the flotation plant. Operations in each of these plants are discussed in the following
sections.
2.2.1 Washing Plant
The washer plant provides for size separation of the matrix ore into clays, fine product, pebble
product, and oversized debris. A flow diagram for the washing plant is presented in Figure 5. In the
washing plant, there are two washer circuits (the North and South washers). Each circuit can receive
matrix ore from two of IMC's four draglines. The two draglines that feed a washer circuit alternate
between mining matrix ore and removing topsoil and overburden such that the circuit is only
receiving ore from one dragline at any given time.
Matrix ore flows through each washer circuit entirely by gravity. The matrix ore pipeline initially
flows into a tub at the top at each circuit. From the tub, the matrix ore enters one of eight parallel
trains. Normally, all trains operate simultaneously in each circuit.
In each train, matrix ore passes over a 20-foot long flat metal screen to separate out greater than 8
inch material. The material that passes through the screen (less than 8 inch material) goes to a
trommel, which is a rotating circular drum with "punch holes" (openings). The first section of each
trommel has 1/2-inch openings (to remove less than 1/2-inch materials), while the second section has
2-inch openings (to remove greater than 1/2-inch and less than 2-inch materials). The greater than 2-
inch materials from the trommels is combined with oversized (greater than 8 inch) materials from the
first screen and classified as debris. Debris is disposed in the clay ponds or placed in an unlined on-
site pile located west of the beneficiation plant (the size of the pile was not determined). Unspecified
quantities of debris are subsequently used on-site in reclamation or road construction, or sold for off-
site use. Materials that are greater than 1/2-inch and less than 2 inches are ground in a ball mill and
sent back through the trommels. The less than 1/2 inch material passes over three vibrating screens
(6 inch x 16 inch), identified by IMC as the primary, secondary, and finishing screens. All three
screens are designed to separate the less than 1/2-inch material into less than 16 mesh (fine product)
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Site Visit Report: IMC Four Corners
Figure 5. Washer Plant Flow Diagram
(Source: U.S. EPA Field Note)
MATRIX ORE
Dobrb
Pebble Product to
Product Pile or Heavy
Media
Separation (if MgO
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Site Visit Report: IMC Four Corners
and greater than 16 mesh (pebble product) materials. The secondary screen is a doubledeck screen,
with the second section used to separate greater than 3/8-inch material from the pebble product.
According to IMC, the greater than 3/8-inch material has a high MgO content. It is classified as
debris and managed with the other debris materials described above.
Between primary and secondary screening and between secondary and finishing screening, the pebble
. product is washed with unspecified volumes of water to remove clay materials. The water is obtained
from the clay pond system. These washing stages are identified by IMC personnel as "log washes."
The effluent from the first log wash goes to a primary clays cyclone. The pebble product is sent to
the secondary screens, while washwater (with entrained clays) flows at an unspecified rate to Clay
Pond F2. The effluent from the second log wash goes to a secondary clays cyclone. The pebble
product is sent to the finishing screen, while washwater (with entrained clays) flows at an unspecified
rate to Clay Pond Fl. Overall, 95 percent of the clay content of the raw pebble product is removed
in the washer plant and reports to the clay ponds.
The fine material from the washer plant is sent to the flotation plant. The pebble product from the
finishing screen is about 64-65 BPL percent (bone phosphate of lime - the anhydrous calcium
phosphate content) and contains about four percent fine material. The pebble product is analyzed for
MgO, iron oxide, and phosphorous content to determine whether heavy media separation is required.
In the pebble product, MgO is mostly in the form of dolomite. If the concentration of MgO exceeds
one percent, the product goes to an unlined storage pile (size not obtained) for feed to the heavy
media separation plant. If the MgO concentration is less than one percent, the pebble product is
stored in piles for off-site shipment to IMC's New Wales phosphoric acid plant.
2.2.2 Heavy Media Separation Plant
The purpose of the heavy media plant is to remove MgO from pebble product that contains greater
than one percent MgO. The heavy media separation process used at the Four Corners plant was
patented by IMC in 1981-82. The plant was installed in April 1991, and is the only such plant in the
phosphate mining industry. According to IMC personnel, the process has significantly expanded the
minable acreage at Four Corners (previously ore with greater than 1.0 percent MgO could not be
profitably mined). In the future, IMC anticipates that other plants may be constructed using the
technology as mining expands to areas South of Four Corners, where raw pebble product would
generally contain MgO in concentrations greater than one percent.
In the heavy media separation plant, an unspecified volume of water is initially added to the pebble
product, which is then passed through two stages of hydraulic screening. The pebble product is
separated into: (1) greater than 5 mesh material, which is classified as waste (see below), (2) less
than 5 mesh to greater than 16 mesh material, which goes to heavy media separation, and (3) residual
15
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Site Visit Report: IMC Four Corners
less than 16 mesh material, which goes to the flotation plant. The wastewater from the screening
stages is recycled within the plant.
The less than 5 and greater than 16 mesh material goes to a hydrocyclone, which is loaded with heavy
media to provide gravity separation. The media is 90 percent magnetite (specific gravity-5.1) and 10
percent ferrosilicon (specific gravity-7.0). Information was not obtained on how heavy media is
stored prior to use or how IMC manages any spent media generated. The overflow (waste) from the
hydrocyclone flows to a media screen. The media passes through the screen and is recycled. The
waste material is combined with the greater than 5 mesh waste material from the initial hydraulic
screening. The underflow from the hydrocyclone goes to another media screen. The media passes
through the screen and is recycled, while the material that flows over the screen is pebble product.
The heavy media plant generates 360,000 tons per year of pebble product, which is combined with
the pebble product that does not require heavy media separation. MC projects that, hi the future, the
plant could be used to produce up to 1,000,000 tons per year of pebble product. Without the heavy
media plant at Four Corners, pebble product with greater than one percent MgO would be waste
material and would be used for reclamation backfill.
The pebble product from the heavy media separation plant is combined with wet pebble product from
the washer plant that did not require separation. The wet pebble product (with 7 to 8 percent water)
is then segregated based on quality (BPL level) and customer requirements, and placed in one of eight
pebble product bins. Product is loaded into railcars through openings in tunnels that pass underneath
the bins. Very little pebble product (or fine product) is shipped off-site in trucks. As indicated
above, all of the pebble product generated at Four Corners is sent to IMC's New Wales Chemical
Plant for processing. Water is drained from the pebble product bins and directed to IMC's water
management system (the quantity recovered was not obtained).
IMC's heavy separation plant generates 120,000-180,000 tons per year of material (greater than 5
mesh material from the initial hydraulic screening and oversized material from the hydrocyclone).
The material, which is primarily dolomite with 50 percent BPL, is temporarily placed in unlined
storage piles (sizes not obtained). Dolomite is an agricultural product; however, the material
generated by IMC cannot be sold commercially as "dolomite" because it does not meet fertilizer
specifications. The material also contains 15 percent acid insoluble sand, 3-5 percent MgO, and well
as unspecified quantities of iron (II) oxide and aluminum oxide. Half of the material is ultimately
ground for use as fertilizer filler. Of the remaining 50 percent, some is permanently managed on-site
in an unspecified manner, some is used for roadbuilding, and the remainder is sold for other off-site
use. The relative percentages in each category were not determined.
16
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Site Visit Report: IMC Four Corners
2.2.3 Flotation Plant
The less than 16 mesh material from the washer plant is pumped to two "unsized" feed bins (100-foot
diameter and 45-foot height). These bins feed the flotation plant, where the material is initially
separated into three size fractions; fine, coarse, and spiral. In the first separation stage, "fine"
material (less than 35 to greater than 150 mesh) is hydraulically separated (by density). The
remaining material (less than 16 and greater than 35 mesh) is then passed over Derrick screens to
separate the "spiral" (less than 16 and greater than 24 mesh) and "coarse" (less than 24 and greater
than 35 mesh) fractions. Approximately 4,000 tons per hour (5.5 million tons per year) of material is
beneficiated in the flotation plant; 2,850 tons per hour (3.9 million tons per year) of fine material,
800 tons per hour (1.1 million tons per year) of coarse material, and 350 tons per hour (0.5 million
tons per year) of spiral material. The flotation methods are different for each of the three fractions.
Figure 7 presents a flow diagram for the flotation methods used at Four Comers. The following
discussions of each flotation method do not describe overall water use and reuse. A broad description
of IMC's water management system is provided in Section 3.1.
In spiral, coarse, and fine separation, the first stage is dewatering to approximately 70 percent solids.
According to IMC, dewatering provides water savings and improves the efficiency of subsequent
conditioning and flotation. In the next step, the fractions are conditioned with the addition of the
flotation reagents. The same reagents are used in each type of flotation. The specific reagents, their
purposes, and the total quantities used annually in the flotation plant are presented in Table 1.
Table 1. Summary of Flotation Reagent Use at Four Corners
(Excluding Amine Flotation)
(Source: IMC Fertilizer, Inc.)
Reagent
Fatty acid and Rerefined
Oil (API #27) Mixture
Sodium Silicate
Ammonium Hydroxide
Purpose
Collector
Sand Depressor
Buffer (to elevate pH to 9)
Range of Quantity Used (in tpy)
8,000-15,000
<5,000
< 5,000
In spiral flotation, conditioning is accomplished in rotating drums. In coarse and fine flotation,
conditioning occurs in a series of four tanks, identified as vertical conditioners. The residence time in
each vertical conditioner tank is 3-4 minutes and reagents are only added to the first tank.
17
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FOUR CORNERS FLOTATION
+ 16
16+24
HYDRAULIC
AND SCREEN
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AND
CONDITION) NO
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SEPARATION
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oo
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TAB.
T
DEWATERINQ
AND
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O'SI2E ISSUE
/^ SPIRAL
( CONCENTRATE
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OEWATERINQ
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ks
c
I
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Site Visit Report: IMC Four Corners
In spiral separation, a Humphrey Helical spiral separator (described by IMC as "a trough with many
ports") is used to accomplish initial flotation. The overflow is spiral product, while the underflow
tailings go to scavenger flotation. Scavenger flotation is accomplished with compressed air agitation
in four banks of standard Denver flotation cells. Each bank of cells has five 50 cubic foot pockets.
The overflow from the scavenger cells is combined with overflow product from the spiral separators.
The underflow discharges to the general mill tailings stream.
According to IMC personnel, it is more difficult to float product from the coarse and fine fractions.
As a result, they require more separation stages. The initial coarse flotation is accomplished in four
banks of Denver cells, each of which has five 300 cubic foot pockets. Aspirators/draft tubes are used
for agitation. The tailings underflow from the initial coarse flotation passes over screens to separate
"O" size material (greater than 35 mesh) and "U" size material (less than 35 mesh). Because the O
size .material contains additional phosphate values, it is directed to spiral separation. The U size
material flows to the general mill tailings stream. The overflow, which is 15-20 percent solids, goes
to a hydrocyclone for dewatering to 65-70 percent solids. The dewatered product is then sent to
sulfuric acid scrubbing.
The initial fine flotation is accomplished in eight banks of Denver cells with five 300 cubic foot
pockets in each bank. The overflow is dewatered to 65-70 percent and sent to sulfuric acid
scrubbing. The tailings underflow goes to the general mill tailings stream.
While both the initial coarse and fine flotation products go to sulfuric acid scrubbing and subsequent
amine flotation, they go through these stages separately. The acid scrub is accomplished with 96
percent sulfuric acid, which removes fatty acids and oil remaining from conditioning. IMC uses
8,000-15,000 tons per year of sulfuric acid. The scrub occurs in two parallel single-stage vertical
tanks, with the amount of acid added depending on the quantities of reagents used in the initial
flotation stages. The residence time in the acid scrubbing tanks is about four minutes. The effluent
from the acid scrub tanks goes to dewatering and countercurrent rinsing with clean water. The
wastewater from the acid rinsing stage is managed separately from other flotation plant wastewaters in
the clay pond system (see Section 3.1). The rinsed product goes to amine flotation.
Amine flotation of fine product is accomplished in four banks of Denver cells, with five 300-cubic
foot pockets in each bank. The amine flotation of coarse product occurs in two separate banks of
Denver cells with five 300-cubic foot pockets in each bank. The residence time in the amine flotation
cells for both coarse and fine products is 7 to 8 minutes. IMC uses less than 5,000 tons per year of
condensate amine. IMC also adds a small amount (about 20 tons per year) of diesel fuel No. 2, to
extend the usage of the condensate amine reagent. No other reagents are used in amine flotation and
the pH is typically neutral.
19
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Site Visit Report: IMC Four Corners
In amine flotation, the sands/tailings are floated and the underflow is the product. The tailings flow
to the general mill tailings stream. The underflow goes to a hydrocyclone to remove coarse and fine
products, both of which are 72 percent BPL and 4 to 5 percent sand. The wastewater flows to an
amine reclaim pond, which is separate from the facility's general water management system.
IMC performs assays to determine the quality (BPL level) of the fine product. The fine concentrate is
then segregated according quality and customer requirements, and placed in one of six open fine
product bins to allow for blending. Similar to the pebble product bins, fine product is loaded into
railroad cars through openings in tunnels that pass underneath the bins. Water is drained from the
fine product bins and directed to IMC's water management system (the quantity recovered was not
available). According to IMC personnel, the fine product generated by the flotation plant contains 7
to 8 percent moisture, while the fine product shipped off-site contains 10 percent moisture. The
reason why the moisture content of the product increases despite dewatering was not obtained.
2.3 Associated Operations
Prior to use, flotation reagents are stored in above-ground tanks in an uncovered reagent yard. The
tanks in the yard include:
One 180,000 gallon fatty acid tank and two 204,000 gallon flotation fuel oil tanks.
Fuel and fatty acids are blended in a 180,000 gallon tank. An additional 180,000
gallon is empty and can also be used for fuel oil/fatty acid mixing as necessary. The
tanks are all surrounded by secondary containment dikes. IMC personnel noted that
Florida Statute 17.710, Florida's used/rerefined oil requirements, has led to use of
better quality used oil. The statute requires that rerefined oil meet specific gravity
levels. Therefore, IMC indicated that they occasionally test the specific gravity of
incoming rerefined oil. No chemical constituent analyses are performed.
Two 39,000 gallon aqueous ammonia tanks (ammonia is purchased in aqueous form).
The aqueous ammonia is mixed with water to obtain anhydrous ammonia, which is
stored in two 18,000 gallon tanks. Neither the aqueous nor anhydrous ammonia tanks
have any form of secondary containment.
Three diesel fuel tanks (the sizes of these tanks were not obtained). Two of the diesel
fuel tanks feed the amine flotation process, while the other tank feeds a boiler in the
reagent yard that can be used to generate steam to heat the reagent tanks, as needed.
According to IMC personnel, heating has not been required to date. All three diesel
fuel tanks have secondary containment dikes.
20
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Site Visit Report: IMC Four Corners
Two 19,800 gallon sulfuric acid tanks. These tanks are surrounded by secondary
containment dikes and are equipped with overflow alarms. The site visit team
observed evidence of spillage around the sulfuric acid tanks.
Two 21,000 gallon concentrated amine tanks (amine is purchased in concentrated
form). The concentrated amine is mixed with water (10 percent amine/90 percent
water mixture) to produce aqueous amine. The aqueous amine is stored in two
51,800 gallon tanks. All these amine tanks are surrounded by dikes.
While all heavy equipment maintenance is performed at IMC's Noralyn facility, a small shop is
located at Four Corners. A chemical storage area behind the shop includes 500 gallon tanks, which
are used to store mineral spirits, antifreeze, motor oil, and hydraulic oil. This storage area has
secondary containment (i.e, dikes). There are no underground storage tanks at the Four Corners site.
All electric power is obtained from off-site sources. According to IMC personnel, construction of an
on-site power plant was considered. However, IMC determined that it would not be economical.
Standby diesel power generators are located at the site for use during power outages.
21
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Site Visit Report: IMC Four Corners
3. WASTE AND MATERIALS MANAGEMENT
This section describes several of the wastes and materials that are generated and/or managed at Four
Corners Phosphate mine and the means by which they are managed. It should be noted that a variety
of wastes and other materials are generated and managed by phosphate extraction and beneficiation
operations.
Some, such as flotation 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 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.
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 tune. 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 following subsections describe 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. Wastes and materials generated at Four Corners include clays (and co-
managed wastewaters), flotation tailings, debris, mine water, runoff, and other wastes and materials
(e.g., waste oil and grease, steel pipe, spent solvents, laboratory wastes, trash, tires, and batteries).
Table 2 presents a summary of all of the materials generated at Four Corners and IMC's management
practices. A discussion of the water recirculation system is also provided in the description of IMC's
clay ponds.
3.1 Clay Ponds and Water Management
The clay pond system at IMC is used to dispose of clay materials removed from the matrix ore in the
washer plant, as well as providing for process water management/recirculation. The complete water
balance for IMC Four Corners is presented in Figure 8. Clay represents 25 percent of the matrix ore
and 7.5 millipn tons of dry clay waste are generated annually. As indicated in Section 2.2.1, clays
are separated from the pebble product in two log washing stages. The effluent from the first log
wash flows to the primary clays cyclone. In the primary cyclone, the pebble product is removed and
22
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Site Visit Report: IMC Four Corners
directed to the secondary screens. The wastewater (with entrained clays) flows by pipeline to Clay
Pond F2. The effluent from the second log wash is directed to the secondary clays cyclone. In the
secondary cyclone, the pebble product is removed and directed to the finishing screen. The
wastewater flows by pipeline to Clay Pond Fl.
Wastewater generated by most flotation plant operations (including countercurrent rinsing) flows into
an open steel launder (identified by IMC as the "secondary launder"). The secondary launder is
approximately 50 feet long by 10 feet wide. The launder also serves as the source of makeup water
for the rinsing operations in the flotation plant. Twelve pumps controlled by an automatic system are
used to regulate the flows in and out of the secondary launder. There is a bleed stream, which flows
by steel pipeline to Clay Pond F2. According to IMC, the flow from the secondary launder
comprises less than one percent of the total flow into the clay pond system. No additional
information was obtained on the specific streams that flow into the secondary launder and their
individual flow rates.
As indicated above, IMC operates two clay ponds at the Four Corners Mine (Fl and F2). Both
ponds are approximately 50 feet deep and are surrounded by 20 foot thick dams constructed of rolled
compacted clay material. The crests of the dams are 35 feet above grade. The site visit team
observed more than ten feet of freeboard in Clay Pond F2 (Clay Pond Fl was not visited). Each
*
pond is divided into multiple cells. The cells are also separated by dams constructed of compacted
clay. Cells F1A-C and F2A-B are currently permitted by the State Department of Natural Resources
and were operational during the site visit. IMC has recently applied for a permit for Cell F2C and
IMC is planning F3 to be located in a previously mined area. The combined area of all cells in Fl is
740 acres (areas of individual cells were not obtained). F2A and F2B each cover approximately 600
acres.
Pervious tailings are placed on the outsides of the dams. The site visit team observed growth on
slopes of the clay ponds, as well as abundant plant and animal life in the ponds and return ditches
(including at least one alligator). The clay ponds were not constructed with liners. IMC claims that a
natural clay liner forms with clay settling. Based on an IMC aerial photograph of the site prior to
construction of F2B, this cell was apparently built over a reclaimed mining area. Studies conducted
in the early 1980s by Gordon & Palm Associates, Inc. state that clay ponds do not pose a risk to
ground water (see Section 4.2.1 for a further discussion of these studies). As a result of this finding,
all clay ponds at phosphate mines in Florida are exempted from State ground-water monitoring
requirements. However, Manatee and Hillsborough Counties require IMC to monitor ground water
at five wells located in the shallow surficial aquifer south of Clay Pond Fl. IMC also conducts
ground-water monitoring at production wells GDP-7 and 8 in the Floridian aquifer. GDP-8 is
located in the mill area south of Clay Pond F2. The location of well GDP-7 was not determined,
although it is assumed to be in the vicinity of GDP-8 (see Section 4.1.1 for greater detail on
23
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Site Visit Report: IMC Four Corners
Table 2. Summary of Waste & Materials Generation and Management at Four Corners
(Source: IMC Fertilizer, Inc.)
Waste
Primary Clays
Secondary Clays
Flotation Wastewater
(except acid scrub)
Acid Scrub Water
Amine Process
Wastewater
Tailings
Debris
Runoff - Plant Area
Runoff - Other Areas
Mine Water
Waste Oil
Steel Pipe
Dragline Grease
Spent Solvents
Laboratory Wastes
Tires
Batteries
Trash
Sanitary Wastewater
Quantity Generated
7.5 million tons dry*
7.5 million tons dry*
Not determined
Not determined
Not determined
19.5 million tons (1991)
Not determined
Not determined
122.08 MOD
Not determined
16,618 gallons/year (1991)
Not determined
1,355 gallons/year
hazardous, no data for non-
hazardous
1,892 Ibs/year proprietary,
294 Ibs/year naptha
Not determined
Not determined
Not determined
10 Containers
Up to 0.0075 MOD
Management Practice
Clay Pond F2, complete recycle
Clay Pond Fl, mostly recycle with discharge from outfall 001
Combined in secondary launder, most recycled from launder,
bleed from launder to clay ponds
Combined with secondary clays and sent to Fl
Managed separately in amine ponds, complete recycle after
makeup water addition
Stored on-site for use in backfill or dam construction
Stored in on-site piles for on-site use in reclamation or as road
based material, or sold for unspecified off-site use
Collected and sent to Fl, 1.1 MOD discharged through outfall
001
Uncontrolled
Stored in ponds as convenient, reclaimed to beneficiation plant
wherever possible
Off-site rerefming, then returned to IMC for reuse
Pipe is reused on-site as long as possible (pipe recycling
program), ultimately sold as scrap
Tested to determine hazardousness, if hazardous sent off-site
to Chem Waste Management, no information on management
if non-hazardous
Sent off-site as hazardous waste
Sent off-site as hazardous waste
Most exchanged with supplier, some shredded and landfilled
off-site
Exchanged with supplier
Containers sent to County Landfill
Treated in aeration system and sent to clay ponds
*7.5 million tons represents total quantity of clays generated.
secondary clays.
No data were available for individual quantities of primary and
24
-------
^ SOURCE
! ,«==
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! FLOROAN A'"* '
AQUIFER J j>
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RAMFALL DIRECT fc
TO PONDS 2.84
MATRIX MOISTURE
3.07
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Sifc VwiV Report: IMC Four Corners
-------
Site Visit Report: IMC Four Corners
ground-water monitoring at Four Corners). In addition, piezometers are located throughout the clay
pond dams to monitor stability.
Clay pond water is reclaimed and returned to the beneficiation plant in unlined ditches. According to
IMC's water balance, 146.88 million gallons per day (MGD) flow into the clay ponds. The total
return flow to the washer and flotation plants from the clay ponds is 129.46 MGD. Clay Pond Fl is
specifically used for managing secondary clay cyclone wastewater and wastewater from the sulfuric
acid washing stage in the flotation plant. The acid scrub water has a pH of 2.5 prior to commingling
with secondary cyclone wastewater in the beneficiation plant (the volumes of acid scrub water and
secondary cyclone wastewater generated were not available). The combined stream that enters Pond
Fl has a pH of 4.5. Pond Fl overflows into a small unlined pond, which discharges to Alderman
Creek through a V-notched weir. The discharge to Alderman Creek is through IMC's NPDES-
permitted outfall 001. As shown in Figure 3, Alderman Creek flows into the North Branch of the
Little Manatee River. According to IMC's water balance, an average of 5.73 MGD of secondary
clay cyclone and sulfuric acid wash water is combined with 1.10 MGD of controlled runoff and
discharged through outfall 001. Assuming that 129.46 MGD are recirculated and 6.83 MGD are
discharged through outfall 001, 10.59 MGD of clay pond water would be lost to other sources (e.g.,
evaporation and infiltration).
According to IMC, the amine flotation operation at Four Corners requires very "clean" makeup
ywater. Therefore, the amine process has a separate water management system. Wastewater from
the amine process flows to a reclaim pond. From the reclaim pond, water flows through a canal to a
"clean" pond. No information was obtained on areas or depths of each pond. Neither of the ponds
or the canal is lined. No analysis is performed on the pond water and no ground-water monitoring is
conducted. Approximately 7.2 MGD of water is added to the clean pond from deep ground-water
wells located in the Floridian aquifer. The clean pond provides the makeup water for amine flotation.
A water balance for the amine pond system was not available.
3.2 Tailings
According to IMC, the flotation plant at IMC generated approximately 19.5 million tons of tailings
during 1991, and 22.9 million tons were projected to be generated during 1992 (no information was
available to indicate whether these quantities represent wet or dry tailings). According to IMC,
because of the grain shape (rounded), IMC's tailings sands cannot be used in construction as filler.
Therefore, tailings are slurried to tailings piles for storage and subsequent on-site use. Water is
decanted from the tailings piles with approximately 16.85 MGD recirculated to the beneficiation
plant. The dried tailings remain stored at the site until they can be used for clay pond dam
construction or reclamation of mined areas (the quantity of dried tailings currently stored on-site was
not available).
26
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Site Visit Report: IMC Four Corners
There are two unlined tailings piles at Four Corners. Dried tailings from one tailings pile will be
used for the construction of the Clay Pond F2C dam. Pond F2C construction was proposed to begin
in September 1992 and be completed 20 months later. According to IMC, the tailings pile planned
for Clay Pond F2C dam construction is 500 feet long, 500 feet wide and 150 feet high. Dried
tailings from the other tailings pile are planned for use in Pond F3 dam construction. Based on
observation, the site visit team estimated that this tailings pile was 1/2 mile long, 1/4 mile wide, and
about 100 feet high. Information on the specific size of this tailings pile was not obtained from IMC.
In addition, no information was obtained on the specific methods used to construct either tailings pile.
IMC personnel indicated that tailings piles are temporary and agreements with Florida DNR require
that the tailings must be used in dam construction or reclamation within 24 months. However, the
pile intended for Pond F3 construction has been located at the site since July 1990 and, according to
IMC, will remain in place for at least two more years from the time of the site visit.
Similar to the clay ponds, the studies conducted by Gordon & Palm Associates, Inc. in the early
1980s concluded that tailings from phosphate operations do not pose risks to ground-water. As a
result, all phosphate operations including Four Corners are also exempted from State ground-water
monitoring for their tailing piles. However, ground-water monitoring is required by Manatee and
Hillsborough Counties. The monitoring wells at Four Corners are located in the vicinity of the clay
ponds, not the tailings piles (see Section 4.1.1 for more detail on IMC's ground-water monitoring
system). Under the conditions of IMC's State surface water discharge permit, IMC is required to
annually collect and analyze a single sample of the tailings pile decant water for hydrocarbons and
PCBs (FL DER, 1987). The results of a December 1991 tailings pile water analysis showed a toluene
level in the tailings of 0.012 mg/1. All other values were below detection limits. An IMC letter
(dated 3/9/92) reporting these data to the State indicated that resampling would be performed to verify
the presence of toluene. Results of the verification testing were not available at the time of the site
visit (IMC, 1992b). According IMC, phthalates are the only hydrocarbons that have generally been
found in Four Corners Mine tailings pile water (elevated phthalate levels are often caused by
laboratory contamination of samples). In addition, IMC personnel indicated that the tailings contain
approximately 2-3 percent heavy minerals (the specific minerals and relative concentrations were not
identified). No information was available on the oil and grease content of the tailings, although the
absence of hydrocarbons would imply that the tailings contain little, if any, oil and grease.
3.3 Debris
Debris consists of oversized materials from the washer plant. No data on waste characterization or
quantities were available for the debris material. Debris is placed in an unlined pile west of the
beneficiation plant or one of the clay ponds. No information was obtained on the current size of the
debris pile. IMC has sold some of the debris (amount and specific reuse not identified). In addition,
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Site Visit Report: IMC Four Corners
debris is used in reclamation and as road base material. No additional information was obtained on
the generation and management of debris materials.
3.4 Runoff
As shown in the water balance for the Four Corners facility, most runoff (up to 122.08 MOD) from
facility property is uncontrolled. However, runoff from the beneficiation plant area (along with
process leaks and spillage), product piles, and haul roads is collected and managed in IMC's clay
pond water management system. Figure 8 shows that 1.1 MOD is discharged directly through outfall
001. The remainder of storm water collected from these areas (specific flows not obtained) is
recirculated to the plant. According to IMC personnel, the water management system has sufficient
capacity to control all collected runoff from the plant for up to a 100-year, 24-hour storm event.
They cited a storm event where the beneficiation plant was covered by a foot of water and no runoff
was discharged uncontrolled (the date, size, and return interval of the event were not determined).
3.5 Mine Water
Mine water collects in active mining areas at the site. IMC pumps mine water from location to
location at the site as necessary based on convenience. IMC did not have readily available estimates
of the total quantity of mine water that accumulates or the quantities stored in specific locations.
Wherever possible, mine water is pumped to the clay pond system for use in the beneficiation plant.
According to IMC's water balance for Four Corners, approximately 1.80 MOD of mine water/pit
seepage flows into the water management system.
3.6 Other Wastes and Materials
Other wastes and materials generated at the site include: waste oil, dragline grease, spent solvents,
laboratory wastes, tires, batteries, trash, and sanitary wastewater and sludge. Each of these and
IMC's management practices are described in the following sections.
3.6.1 Waste Oil
All waste oil generated at Four Corners is collected in 55 gallon drums and shipped off-site to
National Oil Corporation. National rerefmes IMC's waste oil and returns the oil to Four Corners for
reuse. In 1990 and 1991, respectively, IMC shipped 13,178 and 16,618 gallons of waste oil from
Four Corners to National Oil. In 1992, 2,561 gallons had been shipped off-site as of March 18, 1992
(National Oil Service, 1992).
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Site Visit Report: IMC Four Corners
3.6.2 Steel Pipe
IMC has initiated a pipe recycling/reuse program at Four Corners. . Significant quantities of steel pipe
are used for matrix ore transport from mining areas to the beneficiation plant. When this pipe can no
longer be used for ore transport, it is recycled for less demanding on-site uses (e.g., fresh water
transport). When all on-site uses have been exhausted, the steel pipe is sold as scrap. According
IMC personnel, their pipe recycling/reuse program has proven to be profitable. Quantities of pipe
used and resold were not determined. (For more information on pipe recycling, refer to U.S. EPA,
Office of Solid Waste (1994). Innovative Methods of Managing Environmental Releases at Mine
Sites.)
3.6.3 Dragline Grease
Waste dragline grease is collected in 55 gallon drums for off-site disposal. In the past, dragline
grease used at Four Corners contained 1,1,1-trichloroethane (TCE) and waste grease was considered a
hazardous waste (D040). The dragline grease now used at Four Corners no longer contains TCE.
However, IMC continues to detect leaching of residual TCE from the machinery into the grease. As
a result, IMC must test each drum of waste grease to determine whether it is hazardous. In 1991,
1,355 gallons (200 drums) of waste grease were shipped off-site as hazardous waste to Chemical
Waste Management in Ohio. No information was obtained on the quantity of waste grease that was
found to be non-hazardous or how it was managed.
3.6.4 Spent Solvents
IMC uses proprietary solvent for most equipment cleaning in the shops at Four Corners. This solvent
is identified with hazardous waste code D039, which indicates that it contains elevated levels of
trichloroethylene. The proprietary solvent is collected in Safety Kleen containers and ultimately
removed for off-site hazardous waste management by Safety Kleen. In 1991, 1,892 pounds of the
proprietary solvent were shipped off-site.
In addition, IMC washes carburetors with naptha. Spent naptha is collected by Safety Kleen for off-
site management. The spent naptha is identified with hazardous waste codes D006 (cadmium) and
D018 (benzene). In 1991, 294 pounds of spent naptha were shipped off-site.
3.6.5 Laboratory Wastes
Laboratory wastes are placed in lab-packs and shipped off-site in 55-gallon drums. Information on
the specific types of laboratory wastes generated at Four Corners and the quantities disposed was not
obtained.
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Site Visit Report: IMC Four Corners
3.6.6 Tires and Batteries
Most tires are exchanged with IMC's supplier. However, some tires are shredded and landfilled off-
site. All batteries are exchanged with IMC's supplier. No information was obtained on how batteries
and tires are stored on-site prior to pickup. The quantities of tires and batteries sent off-site were also
not determined.
3.6.7 PCBs
The IMC Four Corners Mine was constructed without PCBs. A PCB survey was recently completed
at the site and no PCBs were found.
3.6.8 Trash
All trash generated at Four Corners is shipped to the Manatee County municipal landfill.
Approximately 10 containers per week are sent to the Manatee County landfill (sizes of containers
were not obtained).
3.6.9 Sanitary Wastewater
All sanitary wastewater generated at Four Corners is treated in an on-site wastewater treatment plant.
The facility is a "Type II" extended aeration sewage treatment plant with chlorinated effluent. The
wastewater treatment plant was not visited by the site visit team and no information was obtained on
quantities of chlorine used or storage methods. The capacity of the plant is 0.0075 MOD. The
chlorinated effluent is discharged to IMC's clay pond system. Sewage sludge is land applied (FL
DER, 1989a). No information was obtained on the total quantity of sewage sludge generated or
disposed.
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Site Visit Report: IMC Four Corners
4. REGULATORY REQUIREMENTS AND COMPLIANCE
IMC's Four Corners Mine is addressed by an array of Federal, State, and local environmental and
operating permits and authorizations. They are issued by EPA; the U.S. Army Corps of Engineers;
the Florida Departments of Natural Resources, Environmental Regulation, and Health and
Rehabilitative Services; the Southwest Florida Water Management District; and Hillsborough and
Manatee Counties. These permits and authorizations address the design and operation of the Four
Corners Mine as well as controlling impacts on ground-water, surface water and air. Each of the
permits and authorizations applicable to IMC Four Corners is addressed in the following sections.
4.1 Operational Requirements and Permits
4.1.1 Development of Regional Impact Studies and County Development Orders
Under Florida State Law (380 F.S.), IMC Four Corners was required to prepare Development of
Regional Impact (DRI) plans. Separate DRI plans are required for each county and the DRI plans
must be formally updated when significant modifications/expansions of operations are planned. DRI
plans must specifically include: an analysis of the mine development's impact on the environmental
and natural resources, local economies, and public facilities (Craft and Bakker, Undated). The State
is divided into 11 planning districts and the DRI plans are submitted to the appropriate district
(Tampa District for Four Corners). The Planning District provides comments to the counties on DRI
plans. The counties then issue Development Orders.
IMC Four Corners has separate DRI plans for Manatee and Hillsborough Counties. The initial
proposed Four Corners DRI plan was submitted to Manatee County in September 1975. The DRI
plan describes the planned operation and its environmental impacts on Manatee County, proposed
reclamation activities, and economic impacts. IMC specifically proposed to reclaim (through
revegetation and reforestation) all disturbed areas (including mined land, clay ponds, and tailings
impoundments) (W.R. Grace, 1975). A Development Order was issued on December 27, 1977 by
Manatee County for Four Corners based on the final DRI plan. On March 23, 1989, IMC requested
a substantial deviation from their Manatee County DRI for expansion of mining operations at the site.
A modified Development Order was issued by Manatee County on September 5, 1991 (IMC, 1992c).
An initial DRI Plan similar to the plan for Manatee County was submitted to Hillsborough County
and a Development Order was issued by Hillsborough County in the late seventies/early eighties. No
additional information on the original Hillsborough County DRI or Development Order was available.
IMC has a pending request for a substantial deviation. IMC is proposing to combine the DRIs and
Development Orders for all 54,000 acres of IMC's Four Corners, Lonesome, and Kingsford
operations located in Hillsborough County. Thirty-six thousand acres of these three mines are
permitted for development under separate Development Orders. The proposed DRI requests
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Site Visit Report: IMC Four Corners
authorization to develop the remaining 18,000 acres of reserves. The reserve land proposed for
development at Four Corners consists primarily of "window" out parcels within the facility's existing
boundaries (IMC, 1992d).
The existing Development Orders for Manatee and Hillsborough Counties require IMC to conduct
ground water and surface water monitoring to ensure no impacts on the surrounding environment.
Ground water monitoring wells (MW-1 through .5 and GDP-7 and 8) at Four Corners anre shown on
Figure 2, the Four Corners site map included in Section 1.2. Surface water monitoring locations are
shown on Figure 3, the map of surface water in the area. Ground and surface water monitoring data
must be submitted quarterly to Manatee and Hillsborough Counties.
As shown on Figure 2, five ground water monitoring wells (MW-1 through 5) are located south of
Clay Pond Fl. IMC also conducts monitoring at production wells GDP-7 and 8 in the Floridian
aquifer. GDP-8 is located near the mill and south of Clay Pond F2. The location of GDP-7 was not
specified, although it is assumed to be in the vicinity of GDP-8. No information was obtained on the
ground water flow velocity or direction at the site and no distinction was made in the available
references between upgradient and downgradient wells. In addition, the specific depths of the wells
were not determined. Ground water monitoring data for January 1991 through November 1991 are
presented in Appendix A. All constituents were found below the applicable primary and secondary
drinking water standards except pH, iron, and color. However, based on the findings in the 1983
Palm & Associates Report (see Section 4.2.1), the levels of pH, iron, and color are consistent with
natural conditions in the area.
Surface water monitoring is required monthly at locations SW 1 through 3 and SW 6 (where
monitoring began in October 1991) and semiannually at locations SW 4 and 5. No information was
obtained on the monitoring frequency at location 302, the Little Manatee River prior to the confluence
with Alderman Creek. Surface water monitoring data for January 1991 through November 1991 for
locations SW-1 through SW-6 are presented in Table 3 (no data were available for location 302).
With the exception of outfall 001, there are no controlled discharges from IMC's operations to local
surface waters. As a result, it is not possible to assess the potential impacts of mining operations
(including uncontrolled discharges of mine water and runoff) on surface waters using the data
provided in Table 3. However, the following general observations are noted:
As noted in Section 1.3, surface waters in the area are characterized as acidic.
Monitoring data for location SW-3 (in Alderman Creek below outfall 001) indicate a
more neutral pH than other monitoring locations. This may be the result of the
neutral discharge from outfall 001.
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Site Visit Report: IMC Four Corners
Table 3. Summary of 1991 Surface Water Monitoring
(Source: IMC Fertilizer, 1991)
Parameter
pH
Turbidity
Total Solids
TSS
Chloride
Sulfate
Fluoride
Nitrite
Nitrate
Ammonia N
TKN,
Total N
Organic N
Total P
Total PO4
BOD5
Oil & Grease
Gross Alpha
Radium 226
Radium 228
Dissolved O2
Units
s.u.
NTU
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
pCi/1
pCi/1
pCi/1
mg/1
Monitoring Location
SW-1
4.6-5.6
0.8-3.7
96-276
0.4-80
11-53
2-60
0.1-0.6
0.1
0.1-0.86
0.1-1.8
0.1-3.8
0.1-3.8
0.1-2.2
0.1-0.9
0.9-1.5
0.5-3.2
1-12.1
1-2
0.1-0.5
0.5-1.2
1.5-4.5
SW-2
5.1-6.1
0.6^4.6
72-220
1-4.8
10-36
2.1-38
0.1-1
0.1
0.1-0.49
0.1-1.2
0.6-2.2
0.6-2.5
0.6-1.7
0.1-0.6
0.3-0.9
0.5-8
1-35.5
1-3
0.1-0.7
0.4-1.7
1.1-4.8
SW-3
6.5-7.5
0.4-5
200-412
1-6
5-29
24-328
0.5-2
0.1
0.1-0.49
0.1-1.3
0.3-2.5
0.3-2.7
0.6-1.7
0.4-1.7
1.2-4.4
0.5-4.5
1-5.8
1-11
0.2-1.2
0.6-7.5
3.4-6.9
SW-4
6.4
2.7-6.7
71-172
1-16
11.2-20
15.1-18
0.4
0.1
0.1
0.1-0.2
0.6-1
0.6-1
0.5-0.8
0.1-0.9
N/A
0.7-1.6
1-5.7
1
0.9
1.1
5.6-6.2
SW-5
6.4-6.5
1.3-1.6
63-116
1-1.6
9.2-13 .
9-13.6
0.2
0.1
0.1-0.8
0.1-0.2
0.6-0.7
0.8-1.4
0.4-0.6
0.3
N/A
0.6-1.3
1-103
1-2
1
1.3
5.8-7.1
SW-6
5.7-6.2
1.1-4.5
131-148
1-5.6
29.6
10.5
0.3
0.1
0.1
0.2-0.6
0.6-1.9
1.7-1.9
1.5
0.20.7
N/A
1.5
29-74
1-5
0.4
0.8
1.5-3.2
N/A = No monitoring data available, TKN = Total Kjeldahl Nitrogen
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Site Visit Report: IMC Four Corners
Oil and grease levels in the area, as indicated by monitoring results from locations
SW-1 through SW-6, exceed the applicable Florida water quality standard for oil and
grease in Class III waters (fresh).
November 1991 sampling at location SW-3 showed a Radium 228 level of 7.5 pCi/1,
which exceeds the Florida water quality standard for Total Radium in Class III waters
(fresh) of 5 pCi/1.
Florida water quality standards require a dissolved oxygen content level of greater
than 5 mg/1. Monitoring at locations SW-1, SW-2, and SW-6 consistently shows
dissolved oxygen levels below the State standard. At monitoring location SW-3, three
of ten samples collected during 1991 had a dissolved oxygen content of less than 5
mg/1 (IMC, 1992a).
Hillsborough County also requires IMC to use 11 additional wells (identified as GHO-2, GSO2, GD-
6, SMW-1, SMW-2, SMW-3, SMW-3A, SMW-5, SMW-5A, SMW-6, and SMW-7, specific locations
not obtained) to monitor withdrawal rates hi one area of the property. The original purpose of this
monitoring was to determine the potential impacts of mining operations on one out parcel, identified
by IMC as the Schuman property. These wells are now used to monitor the overall impacts of IMC's
operations on ground water flow. IMC continuously monitors ground water flow in three of these
wells, located in the surficial (GSO-2), intermediate (GHO-2) and Floridian aquifers (GD-6). The
other eight wells are located in the surficial aquifer and ground water flow is monitored monthly.
Withdrawal rate data for these wells were not reviewed by the site visit team.
According to IMC personnel, Manatee and Hillsborough Counties require that the ground water table
at the property boundaries not be permanently lowered more than one foot. As a result, IMC must
install piezometers to measure ground water depth whenever mining occurs within 1,000 feet of
property boundaries. After mining is completed in these areas, the ground water table must be
restored to within one foot of natural conditions. Information on measures used to restore the ground
water table after mining was not obtained.
Both the Manatee and Hillsborough County Development Orders require reclamation of mined and
other disturbed land in compliance with State requirements (see Section 4.1.2). Manatee County
holds a $10,000 bond for reclamation of the site. Hillsborough has required financial guarantees
from IMC. In addition, Manatee County requires that IMC maintain $10,000,000 of environmental
incident liability insurance.
According to IMC personnel, State and County approval is required for construction of all clay ponds
(and any other berms) as well as tailings storage and disposal practices (including intermediate storage
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Site Visit Report: IMC Four Corners
prior to use in reclamation). More specific information on design and operating criteria and the
approval process was not obtained.
4.1.2 State Reclamation Requirements
The Florida Department of Natural Resources (DNR) is responsible for ensuring reclamation of
phosphate mines. The requirements for phosphate mine reclamation are listed in Chapter 16C-16 of
DNR's operating rules. Specifically, phosphate mines are required to submit a conceptual
reclamation plan at least 6 months prior to initiation of mining. In addition, detailed reclamation
plans are required for "logical" reclamation units (typically less than 640 acres) at a site prior to
mining of the unit. However, no approval of conceptual reclamation plans or plans for individual
units is required prior to commencing mining. Specific reclamation requirements include providing
for at least 80 percent vegetative ground cover and 10 percent forest land with 200 trees per acre in
upland areas. Upland slopes must be no steeper than 4:1. The requirements also call for wildlife
habitat replacement and restoration of wetlands (Craft and Bakker, Undated). Financial assurance is
required; however, compliance with the reclamation standards is considered adequate financial
assurance. Finally, unit reclamation and restoration must be completed within two years of cessation
of mining in the unit.
The site visit team did not review the IMC Four Corners conceptual reclamation plans or the plans
for individual units. As indicated previously, approximately two years are required from the initiation
of mining activities to completion of reclamation. Limited information was found on specific ongoing
reclamation activities at Four Corners. IMC did note that they are constructing a scrub habitat in one
mining area. According to DNR personnel, IMC has fully complied with all State reclamation
requirements. Because of IMC's compliance with reclamation requirements, DNR does not require
bonding for Four Corners (Bakker, 1992).
DNR reclamation rules suggest that exposed tailings can not be permanently disposed of above grade.
According to IMC, tailings at Four Corners can only be stored prior to use hi reclamation or clay
pond construction for two years. However, the site visit team noted that the tailings planned for use
in construction of future Clay Pond F3 have already been piled at the site for at least two years and
construction of Pond F3 is not scheduled to be completed until 1993.
4.2 Ground Water
4.2.1 State Ground Water Protection Requirements
In 1982, the Florida Environmental Regulatory Commission passed a rule that required ground water
monitoring systems at phosphate mines by March 1984. However, the rule provided an exemption
from these requirements for facilities that could show subsurface discharges would not impair the
designated uses of the underlying -ground water.
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Site Visit Report: IMC Four Corners
The Florida Phosphate Council contracted with Gordon F. Palm & Associates, Inc. (hereafter referred
to as Palm & Associates) to conduct a comprehensive sampling of mine water, tailings, and clay
ponds as well as shallow and deep aquifers underlying operating and non-operating phosphate mines.
The sampling plan was approved by Florida Department of Environmental Regulation (DER). Clay
water was only sampled at non-operating mines and no sampling was performed at the Four Corners
Mine site. In addition, it is unclear whether this study considered impacts of such units as IMC's
secondary clay/sulfuric wastewater pond (Fl) and the amine process water management system. (Palm
& Associates, 1983a)
The findings of the study were that:
All samples of ground water showed levels of heavy metals, trihalomethanes,
pesticides, and nitrates below primary drinking water standards.
All samples of ground water showed levels of chlorides, copper, and surfactants
below secondary drinking water standards.
Some samples of ground water exceeded primary drinking water standards for
fluoride, turbidity and fecal coliform and secondary drinking water standards for iron,
manganese, pH, TDS, sulfate, and color. All exceedances were generally assumed to
pose no risk because the pollutant levels were consistent with natural ground water
conditions in the area. Some exceedances in ground water samples were explained as
representative of natural conditions, while no explanation was provided for other
exceedances (Palm & Associates, 1983a).
In 1983, Palm & Associates also released the report "Chemicals and Reagents Used in the
Beneficiation of Phosphate Rock." Chapter 2 of the report considered the common reagents used in
phosphate rock beneficiation and the potential impacts on ground water. All chemicals were found to
be unlikely to cause ground water contamination. The following findings are specifically applicable
to chemical use at IMC:
Tall oils/fatty acids - The report considered only one product used by one company.
To the best of the Company's knowledge the product is biodegradable. Ground water
contamination was concluded to be unlikely.
Kerosene/fuel oil - Based on one article that indicates that one product is
biodegradable and the general assumption that fuel oils will be removed by
evaporation, auto-oxidation, and oxidation by microorganisms, ground water
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Site Visit Report: IMC Four Corners
contamination was concluded to be unlikely. The report also notes that kerosene and
fuel oils are very insoluble. , .
Amines - The report refers to a section from a Kirk Othmer reference on fatty acid
amines (not the amines used at Four Corners), which indicates that they are
biodegradable. The report also cites a chemical producer's statements that, while
their single product (a mixture of tallow amines and aliphatic alcohols) may be acutely
toxic, it is unlikely to cause chronic effects.
Ammonia - Ammonia was assumed to be oxidized by bacteria to nitrate. The Florida
drinking water standard for nitrate is 10 ppm. The report cites the results of nitrate
analysis of 184 samples collected from the phosphate mining areas of northern and
central Florida that showed no nitrate levels at or above 10 ppm.
Sulfuric acid - The report considered the potential impacts of sulfate, which has a
secondary drinking water standard of 250 ppm. The Report cited the results of a
1982 Florida Phosphate Council study which showed only two of 16 samples of mill
tailings (both from the same mine) exceeded this level. Excess use of sulfuric acid
was cited for this mine. Ground water monitoring in the area of this mine show
levels below 250 ppm. A few samples collected from ground water underlying other
phosphate mines were noted as exceeding 250 ppm. The report suggested that these
exceedances were caused by other sources. Therefore, the use of sulfuric acid was
concluded to pose low potential for ground water contamination (Palm & Associates,
1983b).
Based on the results of these studies, DER exempted all phosphate mining operations (including Four
Corners) from State ground water monitoring requirements in 1984. DER requirements are limited to
the annual analysis of Four Corners mill tailings required under IMC's surface water discharge permit
(see Section 3.2).
4.2.2 Summary of Ground Water Monitoring and Use at Four Corners
While Four Corners is exempted from State ground water monitoring requirements, ground water use
and potential degradation are addressed by a number of other State and local permits. The ground
water monitoring wells at Four Corners, their purposes (water supply and/or environmental
monitoring), and the applicable permits are summarized below. More detailed information can found
in this section under the descriptions of the specific permits.
Wells MW-1 through MW-5 are located in the surficial aquifer and IMC is required
under their County Development Orders to monitor these wells to determine potential
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Site Visit Report: IMC Four Corners
impacts on local surface waters (the surficial aquifer recharges surface water in the
area) (see Section 4.1.1).
Wells GHO-2, GSO-2, GD-6, SMW-1, SMW-2, SMW-3, SMW-3A, SMW-5, SMW-
5A, SMW-6, and SMW-7 are only used to monitor withdrawal rates. GHO-2 is
located in the Hawthorn aquifer and GSO-2 is located in the Floridian aquifer. The
other wells are all located in the surficial aquifer. Monitoring of these wells is
required under IMC's Hillsborough County Development Order to measure the
potential for drawdown (see Section 4.1.1).
Wells GDP-7, GDP-8, and GDP-10 are production wells in the Floridian aquifer that
provide water to the flotation plant (primarily the amine flotation process). Under
IMC's County Development Orders, GDP-7 and GDP-8 are monitored to assess
potential impacts on the Floridian impacts. Wells FCS-1 through FCS-7 are also in
the Floridian aquifer and provide pump seal water. The withdrawal rates from these
wells are regulated under IMC's water use permit (see Sections 4.1 and 4.5).
Well PTW-3 in the Floridian aquifer provides an average of 0.06 MGD of potable
water to the plant. The operation of this well is regulated under IMC's potable water
permit (see Section 4.6.4).
4.3 Surface Water
4.3.1 NPDES Permit
The State of Florida is not authorized to implement the NPDES permitting program. NPDES Permit
No. FL0036412 for IMC Four Corners was issued by EPA Region IV. The current NPDES permit
was issued on September 30, 1991 and expires on September 30, 1996. The permit establishes
effluent limitations and monitoring requirements for the discharge from outfall 001 (below Pond Fl)
to Alderman Creek. The discharge includes wastewater from the secondary clay cyclone in the
washer plant, wastewater from acid scrubbing in the flotation plant, mine water, treated sanitary
wastewater, and storm water. Ninety percent of the total annual discharge from outfall 001 occurs
during storm events. However, according to IMC personnel, a continuous discharge is maintained to
avoid stagnation in Pond Fl. The effluent limitations in the permit are based on the effluent
guidelines for discharges of process wastewater and mine dewatering from phosphate mines (see 40
CFR Part 436, Subpart R) and the permit writer's best professional judgment (BPJ). The specific
permit limitations are presented in Table 4 (U.S. EPA, 1991a).
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Site Visit Report: IMC Four Corners
Table 4. NPDES Permit Requirements for Outfall 001
(Source: U.S. EPA, 1991a)
Parameter
Flow
TSS (non-
volatiles only)
TSS (all)
Total
Phosphorous*
Dissolved
Oxygen
Un-ionized
Ammonia"
Total Ammonia
Temperature
Total Kjeldahl
Nitrogen
Specific
Conductance***
PH
Discharge Limitations
Daily Minimum
N/A
N/A
N/A
N/A
5.0 mg/1
N/A
N/A
N/A
N/A
N/A
6.0 s.u.
Daily 30-Day
Average
Report (MOD)
12 mg/1
30 mg/1
Report (mg/1)
.»
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Daily Maximum
Report (MOD)
25 mg/1
60 mg/1
Report (mg/1)
N/A
0.02 mg/1
Report (mg/1)
Report (°C)
Report (mg/1)
1,275
(pimhos/cm)
9.0 s.u.
Monitoring
Frequency
Weekly
Weekly
Weekly
Weekly
Monthly
Monthly
(Calculated)
Monthly
Monthly
Monthly
Monthly
Weekly
N/A = Not Applicable (i.e., no limit or monitoring requirement)
'The permit only requires monitoring for phosphorous. However, if the monthly average exceeds 3
mg/1 for more than one month of a calendar year, IMC is required to: (1) document the monitoring
data, (2) assess the cause and origin of the phosphorous discharge, (3) describe current phosphorous
control practices, (4) evaluate the environmental significance of the elevated levels, and (5) identify
reasonable methods to abate. A notice of the discharge must be publicly released in a local
newspaper.
"The un-ionized ammonia concentration is calculated monthly as described in the permit using the
total phosphorous and temperature levels.
"The specific conductance must not be more than 50 percent above background or exceed 1,275
/imhos/cm, whichever is less stringent.
39
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Site Visit Report: IMC Four Corners
According to IMC personnel, Four Corners does not have a Spill Prevention, Countermeasure, and
Control Plan, because all potentially hazardous materials are "contained" at the site. The NPDES
permit required IMC to update their best management practice (BMP) plan within six months of
issuance of the permit and implement the updated plan within 18 months (U.S. EPA, 1991a). At the
time of the site visit, IMC was updating their BMP Plan for Four Corners.
Table 5 summarizes discharge monitoring data for outfall 001 from September 1990 through
December 1991.
IMC conducts self-inspections of the permitted discharge twice per week and EPA conducts annual
NPDES compliance inspections.
4.3.2 State Surface Water Discharge Permit
The discharge from outfall 001 is similarly addressed by a State Discharge Permit. The previous
Permit (No. 1041-111263C) was issued on April 23, 1986 and expired on April 23, 1991. According
to IMC, no new permit has been issued to date and the facility continues to follow the requirements
of the previous permit. The effluent limitations and monitoring requirements for flow, TSS (both
"total" and "nori-volatiles only" monitoring required), total phosphorous, and pH are equivalent to the
requirements under IMC's NPDES permit. Previously required monitoring for fluorides, specific
conductance, un-ionized ammonia, dissolved oxygen, total kjeldahl nitrogen, and total sulfate was
deleted, at IMC's request, as of a June 22, 1987 modification to the permit. As shown previously in
Table 4, however, IMC is required to monitor for all of these parameters, except sulfate, under their
current NPDES permit. IMC has continued to monitor and submit data for sulfate even though it is
not required under either their NPDES or State Discharge Permits. In addition, as required under
State regulations, IMC is about to undertake a study to determine whether permit limits are adequate
to ensure compliance with State water quality standards (FL DER, 1987).
The expired permit also required an annual analysis of a single tailings decant water sample for
hydrocarbons and PCBs. Toluene (at 0.012 mg/1) was the only constituent detected in a December
1991 tailings decant water sample. As indicated previously, verification sampling and analysis was to
be performed after the site visit. DER is awaiting the results of verification sampling (IMC, 1992b).
To assess compliance with State Discharge Permit requirements, DER conducts annual inspections at
Four Corners.
40
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Sire Visit Report: IMC Four Corners
Table 5. Summary of Monitormg Data for Outfall 001 (9/90 -12/91)
(Source: IMC 2nd quarter, 1992)
Parameter
Flow
pH
Fluoride
TSS (all)
TSS (non-volatiles only)
Dissolved Oxygen
Total Ammonia
Un-ionized Ammonia
Temperature
Sulfate
Kjeldahl Nitrogen
Specific Conductance
Gross Alpha
Monitoring Results
0.056 - 42.275 MOD
6.42 - 7.7
ND - 2.7 mg/1
0 - 28 mg/1 ,
0 - 18 mg/1
5.3 - 22.7 mg/1
Not Available
ND - 0.0155 mg/1
Not Available
17.8 - 245.4 mg/1
0.21 - 2.91 mg/1
296 - 603 ^mhos/cm
1.0-6.8pCi/l
Comments
Very high flow during summer
Within permit limits
Required under previous NPDES permit
Within permit limits, most values less
than 5 mg/1
Within permit limits, most values less
than 1 mg/1
Within permit limits
Report only requirement, used to
calculate un-ionized ammonia
Calculated as noted above, within permit
limits
Report only requirement, used to
calculate un-ionized ammonia
Required under previous NPDES permit
None
Within permit limits
Required under previous NPDES permit
ND = Not Detected
41
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Site Visit Report: IMC Four Corners
4.4 Air
DER issues permits for most air pollution sources; however, a permit is not required for mining,
which is considered an area source. Mining operations are generally required by DER to take
reasonable precautions to minimize fugitive dust emissions and ensure compliance with ambient air
quality standards (Craft and Bakker, Undated). According to IMC, all dust settles on-site and no off-
site dust problems have been caused by the Four Corners operations. Where necessary, water
wagons are used for on-site dust control.
DER has issued Permit No. A041-197666 for air emissions from IMC's heavy media separation
plant. This permit was issued on June 19, 1991 and expires on June 19, 1996. The permit
specifically addresses two emissions sources: Emission Source 01 - the magnetite storage bin and
Emission Source 02 - the ferrosilicon storage bin. Particulate emissions from these two sources are
controlled during unloading and transfer by two fabric filter baghouses (one baghouse for each bin).
No information was obtained on the quantity of dust collected or how collected dust is managed. The
permit notes that no chemical additives are used to prevent oxidation or decomposition of the media,
improve kinetic stability of suspension, or reduce media viscosity. The permit includes the following
requirements:
(1) The maximum allowable paniculate emissions rate from both bins is 0.6 ton per year.
(2) Visible emissions must not exceed 5 percent opacity.
(3) The maximum transfer rate for magnetite and ferrosilicon cannot exceed 15 tons/hour
and 5 tons/hour, respectively:
(4) Annual visible emissions testing is required for each bin (within 15 days of April 15),
data must be submitted to DER, and testing must be performed at or near maximum
transfer rates.
(5) Proof of compliance with the visible emissions limit allows IMC to assume
compliance with the paniculate limit. However, DER may require paniculate testing,
as necessary.
(6) Reasonable precautions must be taken against uncontrolled emissions (FL DER,
1990a).
IMC conducts self-inspections of the emissions sources monthly and DER conducts air permit
compliance inspections at least annually.
4.5 Water Use Permit
The State of Florida is divided into five water management districts, which regulate the use of water
resources, including wetlands, both during mining and after mining activities have been completed.
The Southwest Florida Water Management District issued Water Use Permit No. 203573.3 to IMC
42
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Site Visit Report: IMC Four Corners
for the Four Corner Mine on March 27, 1990 with an expiration date of March 27, 1996. The
permit specifically addresses IMC's 11 water supply wells in the deep Floridian aquifer. Four of
these wells (GDP-4, GDP-7, GDP-8, and GDP-10) are high volume production wells that
continuously provide "clean" water to the amine flotation process (annual average 7.2 MGD) and
makeup water to the clay pond water management system during the dry season (annual average 3.54
MGD). GDP-4 is only allowed to be used as a standby well. The remaining seven wells (FCS1 -
FCS7) are much lower volume wells that are used to provide pump seal water. Table 6 provides
recent pumping rates for March 1991 through February 1992 for each of these wells. Table 6 also
provides a comparison of the actual withdrawal rates to the permitted levels for each well. As shown
in this Table, IMC has frequently exceeded the daily average withdrawal limits for two of the pump
seal water wells and recently began exceeding the daily average limits for the high volume production
wells.
The permit also requires IMC to perform quarterly monitoring at well GDP-7 in the Floridian Aquifer
for chlorides, sulfates, and TDS. These data were not reviewed by the site visit team. However,
IMC conducts monthly monitoring of well GDP-8 in the Floridian aquifer for sulfate, specific
conductance, fluoride, gross alpha, chloride, TDS, pH, and nitrate.
In addition, the water use permit requires IMC to submit reports to the Southwest Florida Water
Management District by April 1, 1991 and August 1, 1995 on water conservation activities at the site.
These reports must address both the flotation circuit and water management system (SWFWMD,
1990). The 1991 report was not obtained or reviewed by the EPA site visit team.
4.6 Other Permits
4.6.1 Wastewater Treatment Plant Operating Permit
DER issued Permit No. D041-155739A to IMC on 12/16/88 for operation of the Four Corners
sanitary wastewater treatment plant. The permit includes the effluent limits and monitoring
requirements presented in Table 7 for the discharge from chlorination to the clay pond system.
Sewage sludge is land applied on-site. No information was obtained on IMC's land application
methods or the land application area. The permit provides that the sludge must be sampled annually
and tested for: total nitrogen, total phosphorous, total potassium, cadmium, copper, lead, nickel,
zinc, pH, and percent total solids (FL DER, 1989a). These data were not obtained.
Effluent and sewage sludge monitoring data must be submitted monthly to DER. In their October
1989 monthly report, IMC reported greater than 2,400 counts of fecal coliform per 100 milliliters of
effluent. All other parameters were below permit limits. As a result of the elevated fecal coliform
level, DER sent a warning letter to IMC on February 23, 1990 requesting development of a plan of
43
-------
Table 6. Ground-water Withdrawal Rates for IMC Four Corners
(Source: IMC, 1992e)
Date
Daily Avg Limit
Daily Max Limit
3/91
4/91
5/91
6/91
7/91
8/91
9/91
10/91
11/91
12/91
1/92
2/92
Well Flow Data (in MGD)
GD-7
3.5
7.05
0.801
0.670
3.501
3.053
1.442
3.519
4.578
3.348
4.387
3.473
4.295
2.102
GD-8
3.5
7.05
3.999
4.122
3.919
3.570
2.993
3.827
2.379
1.603
0.005
2.084
4.382
3.990
GD-10
3.5
7.05
4.529
3.266
0.046
0.001
1.605
0
2.296
4.760
4.692
2.036
3.407
3.724
FCS-1
0.08
0.144
0.122
0.108
0.119
0.043
0.103
0.202
0.226
0.216
0.247
0.211
0.187
0.185
FCS-3
0.08
0.144
0.031
0.027
0.027
0.029
0.036
0.002
0.019
0.031
0.026
0.053
0.050
0.059
FCS-4
0.08
0.144
0.083
0.076
0.079
0.090
0.101
0.007
0.056
0.096
0.053
0.044
0.054
0.065
FCS-6
0.08
0.144
0.057
0.075
0.096
0.086
0.107
0.105
0.150
0.116
0.075
0.032
0.044
0.190
FCS-7
0.08
0.144
0.028
0.035
0.015
0
0.006
0.021
0.025
0.046
0.054
0.017
0.021
0.032
FCS-8
0.08
0.144
0
0
0
0
0
0
0
0
0
0
0
0.059
TOTAL
10.81
15.01
9.649
8.380
7.801
6.871
6.393
7.684
9.729
10.216
9.538
7.949
12.438
10.406
I
I
I
I
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Site Visit Report: IMC Four Corners
Table 7. Effluent Limits and Monitoring Requirements for
the Discharge from IMC's Wastewater Treatment Plant
(Source: FL DER, 1989a)
Parameter
BOD and TSS
Fecal Coliform
Nitrate
Flow
pH
Monitoring Frequency
Every other month
Quarterly
Every other month
Daily, 5/week
Daily, 5/week
Effluent Limit
20 ppm annual avg
30 monthly avg.
45 weekly avg.
60 sample max.
200 counts/100 ml (annual and
monthly avg)
12 mg/1
0.0075 MOD
6 - 8.5 s.u.
action (FL DER, 1990b). hi response, on March 7, 1990, IMC notified DER that the exceedance
was caused by an empty chlorine tank at the tune of sampling and that IMC would take action to
ensure that this would not happen again (IMC, 1990a).
IMC conducts self-inspections of the wastewater treatment plant five times per week and DER
performs compliance inspections at least annually.
4.6.2 Wetlands Permits
Wetlands are located throughout the Four Corners Site in the Little Manatee River, Alderman Creek,
Payne Creek, and Horse Creek drainages. Mining operations in wetlands areas are permitted by DER
and the U.S. Army Corps of Engineers (hereafter referred to as the Corps). IMC's current
operations in wetlands and the applicable permits are listed hi Table 8.
4.6.3 Tank Permits
In 1991, DER adopted a tank rule (17-762 F.A.C) requiring secondary containment for all "pollutant"
storage tanks, including tanks in IMC's Four Corner reagent storage yard and the shop tanks. All
regulated tanks at Four Corners have secondary containment (ammonia tanks, which do not have
secondary containment, are specifically exempted from rule requirements). IMC conducts self-
inspections of their storage tanks monthly and the State and/or Counties conduct tank inspections at
least annually, sometimes semi-annually. In 1991, inspections by Manatee County (October 23,
45
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Site Visit Report: IMC Four Corners
Table 8. Summary of Wetlands Permits for IMC Four Corners Mine
Permit Number/
Issuing Agency
Date of Issuance/
Expiration Date
Permit Description and Requirements
Corps Permit No.
89IPC-20418
2/26/90 - 2/26/95
This permit covers mining activities in approximately
63.9 acres of wetlands. IMC will subsequently
reclaim 90 acres of freshwater marsh and 24.25 acres
of bay swamp. Eighty percent plant cover must be
achieved. The reclamation must be completed within
2 years of mining cessation.
DER Permit No.
29,41&531404579
Corps Permit No.
199004637
6/16/89 - 6/16/99
12/2/91 - 10/23/96
The DER permit addresses a broad range of mining
activity in 527.6 acres of herbaceous wetlands, 68
acres of shrubby wetlands and 45.8 acres of forested
wetlands in the headwaters of Alderman Creek,
Horse Creek, and Payne Creek. IMC is required to
restore 830.9 acres of herbaceous wetlands, 75.6
acres of shrubby wetlands, and 155.6 acres of
forested wetlands in these basins, permit identifies
specific reclamation activities (including use of mine
tailings) for each disturbed area.
The Corps permit addresses a subset of the area
covered by the DER permit.
DER Permit No.
291638103
Corps Permit No.
89IPC-20393
7/17/89 - 7/17/99
7/17/89 - 9/18/94
Both the DER and Corps permits call for the
construction of an elevated pipeline and three
road/pipeline crossings over the Little Manatee
River, and a dragline walkpath under Payne Creek.
As a result of this action, approximately 1 acre of
wetlands will be filled. As required by the
Hillsborough County, IMC is required to create 1.5
acres of herbaceous wetlands and 1.5 acres of
forested wetlands within the affected drainage basins.
Sources: FL DER, 1989b and c; FL DER, 1990b; IMC 1990b and c; U.S. Army, 1986; U.S
Army, 1989; U.S. Army 1990; and U.S. Army 1990b.
1991) and Hillsborough County (July 7, 1991) found no violations at Four Corners (FL DER, 1991a
andb).
4.6.4 Domestic Water Supply Permit
Well PTW-3 provides an average of 0.06 MOD of potable water to the plant. Potable water is used
for domestic needs as well as equipment washing. Construction and operation of well PTW-3 is
addressed by Permit No. W4-113203191 issued by the State Department of Health and Rehabilitative
46
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Site Visit Report: IMC Four Corners
Services (DHRS). The current permit became effective on September 10, 1991 and expires on
September 10, 1996. DHRS conducts at least annual inspections at Four Corners. The site visit team
did not review this permit or recent DHRS inspection reports. According to IMC personnel, there
have been no violations of permit requirements to date.
47
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Site Visit Report: IMC Four Corners
REFERENCES
Bakker, Joe. 1992 (March). Conversation with Joseph Bakker, Division Director, Division of
Mining, Florida Department of Natural Resources.
Craft, Jeremy and Bakker, Joe. Undated. Overview of Environmental Regulation in Florida. Squaw
Creek. Florida Department of Natural Resources.
Florida Department of Environmental Regulation. ,1987 (June 22). Modified Permit No. 1041-
111263Cfor Surface Water Discharge from Outfall 001.
Florida Department of Environmental Regulation. 1989a (February 16). Modified Permit No. D041-
157739 for Operation of Wastewater Treatment.
Florida Department of Environmental Regulation. 19895 (June 16). Wetlands Permit No.
29,41&531404579.
Florida Department of Environmental Regulation. 1989c (July 17). Wetlands Permit No. 29638103.
Florida Department of Environmental Regulation. 1990b (February 23). Warning Letter from
William Priesmeyer, Florida DER to IMC, Regarding Four Corners Wastewater Treatment Plant
Permit No. D041-1557739.
Florida Department of Environmental Regulation. 1990a (May). Air Emissions Permit No. A041-
197666 for Magnetite Storage Bin and Ferrosilicon Storage Bin.
Florida Department of Environmental Regulation. 1990c (October 31). Letter from DER to J. V.
Burleson, IMC, Approving Modification to Wetlands Permit No. 29638103.
Florida Department of Environmental Regulation. 1991a (July 11). Pollutant Storage Tank System
Inspection Report Form. Completed by Hillsborough County.
Florida Department of Environmental Regulation. 1991b (October 16). Pollutant Storage Tank
System Inspection Report Form. Completed by Manatee County.
Florida Department of Environmental Regulation. 1992 (January 21). Letter from William
Washburn, Florida DER, to J.V. Burleson, IMC, Regarding Results of January 15, 1992 Sewage
Treatment Plant Inspection.
Florida Institute of Phosphate Research (FIPR). 1991 (May). Radiochemistry of Uranium-series
Isotopes in Groundwater. Bartow, FL.
Gordon F. Palm & Associates, Inc. 1983a (March 15). Water Data Acquisition Program: Surface
Water & Ground Water Quality, Volumes 1 and 2.
Gordon F. Palm & Associates, Inc. 1983b (April 18). Chemicals Used in the Beneficiation of
Phosphate Rock.
48
-------
Site Visit Report: IMC Four Corners
IMC Fertilizer, Inc. 1990a (March 7). Letter from G. Greg Williams, IMC, to William Priesmeyer,
Florida DER, Response to February 23, 1990 Warning Letter from DER.
IMC Fertilizer, Inc. 19905 (September 18). 1989 (April 11). Application for Wetlands Permit
Submitted to Florida DER and U.S. Army Corps of Engineers.
IMC Fertilizer, Inc. 1990c (September 18). Letter from Robert Yarbrough, IMC, to Ken Huntington,
Florida DER, Requesting Modification of Wetlands Permit No. 29638103.
IMC Fertilizer, Inc. 1991. NPDES Discharge Monitoring Reports for January to December 1991.
IMC Fertilizer, Inc. 1992g (January 14). Letter from Doreen Donovan, IMC to Elizabeth Bishop,
U.S. Army Corps of Engineers.
IMC Fertilizer, Inc. 1992f (February 7). Letter from G. Greg Williams, IMC, to William Washburn,
Florida DER, Response to January 21, 1990 Letter from DER.
IMC Fertilizer, Inc. 1992h (February 18). Letter from Jay Allen, IMC, to Colonel Terrence Salt,
U.S. Army Corps of Engineers.
IMC Fertilizer, Inc. 1992a (February 27). Letter from G. Greg Williams, IMC, to Tom Drexhage
and Neal Parker Submitting Results of IMC"s Four Corners Mine Monitoring Program: Quarter IV
- 1991.
IMC Fertilizer, Inc. 1992e (February). Southwest Florida Water Management Division Compliance
Summary.
IMC Fertilizer, Inc. 1992b (March 9). Letter from G. Greg Williams, IMC to Richard Garrity,
Florida DER Regarding Annual Tailings Decant Water Sampling.
IMC Fertilizer, Inc. 1992d (April). Executive Summary, Hillsborough County Substantial Deviation,
DRINo. 213.
IMC Fertilizer, Inc. 1992c. History of Manatee County Development of Regional Impacts.
National Oil Service. 1992. Record of Monthly Used Oil Shipments from IMC Four Corners.
Southwest Florida Water Management District (SWFWMD). 1990 (March 27). Water Use Permit
No. 203573.3.
United States Environmental Protection Agency. 1991b (July 19). NPDES Compliance Inspection
Report, Permit No. FW036412.
United States Environmental Protection Agency. 1991a (September 30). National Pollutant Discharge
Elimination System Permit No. FL0036412.
United States Department of the Army, Corps of Engineers. 1986 (August 8). Dredge and Fill
Permit No. 85IPB-21042.
49
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Site Visit Report: IMC Four Corners
United States.Department of the Army, Corps of Engineers. 1989 (July 17). Dredge and Fill Permit
No. 89IPC-20393.
United States Department of the Army, Corps of Engineers. 1990 (February 26). Dredge and Fill
Permit No. 89IPC-20418.
United States Department of the Army, Corps of Engineers. 1991b (December 2). Dredge and Fill
Permit No. 199004637.
United States Department of the Army, Corps of Engineers. 1991a (December 3). Notice of Non-
compliance. Dredge and Fill Permit No. IPC-20418. Issued to IMC by Jacksonville District
Corps of Engineers.
W.R. Grace & Co. 1975. Executive Summary: Development of Regional Impacts for Four Corners
Mine. Submitted to Manatee County.
50
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Site Visit Report: IMC Four Corners
APPENDIX A
1991 GROUNDWATER MONITORING DATA
-------
MIC Fertilizer - Foot Comers Mine
Manatee County - Ground Water StmpOng AagutoMiante
tocMtan: UW-t
1 PH
t GoodueinAK
roto/M*a0M
AimonfcMtHVM
Mtott
A*ft*»
SuMri*
fiuttte
Total PhotphoiiM-P
10 Total &9*nieC*toon
It Total AJtMiCtCOi
It CMlctom
13 MVVMMJJII
14 Sodium
fS ftXMrt/n
10 CAferi*
17 nuorM*
10 AfMAfe
10 Bmhm
» CMftntom
21 CIMoniMM
« kon
20 LMrf
24 Mtreury
25 SMMUm
ftf Siiu^f
n coht
tt CUmndQnMff
20 SurttcttiMt
10 GtouMphm
31 HftUumlH
« AM/AMI 220
own
SU.IMI
UmAiMfew
"V*
104
004
«0>f
"V*
**
mt*
*9*
*9*
itgt
M0f
mgA
m&
mtf
mgn
"V
mp*
IM0A
«vf
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nH
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-------
IMC Fertilizer Four Comers Mine
Manatee County - Ground Wai* Sampling flaqufre/nanfs
££L ***
1 pH
2 CwductnMf
3 TotilMivQM
4 /tomnonu Mf/qgM
4 Nan*
9 NttiH»
T Sutltt*
» SUM*
9 Tot»IPtto*>tKJtut-P
19 r
tf CMor
ft OfMMfSfM**
29 Suihctintt
30 QKMtUpt*
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#9*
n»9ll
mtf
mot
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nt*
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"0*
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mf/l
1*9*
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tntf
mtf
mg/t
intf
mgH
ma»
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IR0/I
mtf
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*9*
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,
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,
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199
23
91
9.23
919
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49
10
12.7
91
199
99
9919
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to
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2.9
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Of
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010
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2K
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49
-------
IMC Foamier - Four Corners Mine
Manatee County - Ground Wttor SampHng /toqutanMnts
Loorifart. UW-3
£t+r^^m^0l^f
rwpvM*
1 pH
X Conductivity
3 ToUlNHOQtn
4 Ammonia NHtcfMt
tf MNMtt
MMW
f SuHt*
9 Suit*
9 ToUlPttOlpltOttM-P
to rotfl/OrffMfeCMftan
fi r«tafA*«»ciau
M CMMm
IJ UlflfWlftM
M $adKum
15 Pumtitum
U ClOoiUf
17 Flunk*
tt Afwnic
Iff 0«<«M
20 CMtflWMTI
If CArom^MR
« »CIH
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It
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If
-------
IMC Fertilizer- Four Cornors Mine
Uanaioa County - Ground Water Sampling Roqutomonls
locator UW-3 " ^__
t Conduetiritf
$ ToUIMtofM
4 Amwonte MMrepM
s Mew*
0 Mfrto
f SuttaH
t Sum*
0 TotftPtioiptio/im-P
it roMOr0Mfe Often
ff ToUIMIituCfOOi
It CMfem
13 AfcplMMMt
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IS AtoMta
t* CMdridt
IT ftuottto
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20 Ctdmtum
ft CtHomium
tt Iron
£J l-W
-------
Site Visit Report: IMC Four Corners
APPENDIX B
COMMENTS SUBMITTED BY IMC FERTILIZER, INC., ON DRAFT SITE VISIT REPORT
-------
Site Visit Report: IMC Four Corners
The following is a list of IMC's changes to the Draft Report 'Mine Site Visit: IMC Four Corners Mine'
dated September 1992. The Page and Section numbers in the following list correspond to the
September, 1992 Draft report. The paragraph numbers were obtained by counting the number of
paragraphs under each Section heading, and therefore may not correspond to the paragraph number
on a particular page.
Page 1, Section 1.1:
Page 2, Section 1.1:
Page 2, Section 1.1:
Page 2, Section 1.2, paragraph 1:
Page 2. Section 1.2, paragraph 2:
Page 5, Section 1.2, paragraph 1:
Page 5, Section 1.2, paragraph 2:
Page 5, Section 1.2, paragraph 3:
Page 5, Section 1.3.2, paragraph 1:
Revise list of participants to reflect recent IMC
management changes.
Jim Burleson's new title is "Vice President, Rorida
Operations*.
Revise list of participants to reflect recent IMC
management changes.
Lee Thumer's new title is "Vice President & General
Manager, Rorida Minerals Operations'.
Revise list of participants to reflect recent IMC
management changes.
Gene Armbrister's new title is "Production Services
Manager".
Inset the words "beneficiation plant" in sentence 1 to
better define operations. Add "Polk County" in
sentence 2 to the list of counties that the Four Comers
Mine is located in,
Replace the word "ore" with "product" to more
accurately describe IMC's reserves in sentences 1, 2,
& 4. Delete the last sentence because operations were
not expanded to 7 days as originally scheduled.
Replace the words "concentrate product" with
"flotation feed" in sentence 3.
Replace the words "fine concentrate" with "flotation
feed" in sentence 1. Insert the words "through
hydraulic sfcino" to better describe the flotation process
in sentence 1. Insert the words "and to other
customers" to indicate that IMC's products are shipped
to other customers in addition to the New Wales Plant
in sentence 3.
Replace the words "disposed of" with "stored" in
sentence 2. Add the words "and used as a backfill for
reclamation, and in clay pond construction." to better
describe the use of tailings in sentence 2.
Replace the word "mill" with "plant" in sentence 2.
Replace the words "Clay Pond F1" with "water
recirculation system" in sentence 3. Replace the words
"a tributary" with "tributaries" in sentence 4. Insert
the words "disturbed mining areas" in sentence 5.
Insert the phrase "and the North Fork of the Manatee
River" in sentence 6. Replace the word "mill" with
B-l
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Site Visit Report: IMC Four Corners
Page 7, Section T .3.3. paragraph 1:
Page 7, Section 1.3.3. paragraph 2:
Page 7, Section 1.3.4. paragraph 1:
Page 10, Section 1.3.4, paragraph 2:
Page 11. Section 1.3.5, paragraph 1:
Page 13, Section 2, paragraph 1:
Pag« 13. Section 2.1. paragraph 1:
Page 13. Section 2.1. paragraph 2:
Page 13, Section 2.1, paragraph 3:
Page 14, Section 2.1, paragraph 5:
"plant" in sentence 6. Insert the phrase "and the Army
Corps of Engineers* in the last sentence (No.S).
Insert the words 'variable thickness", replace the
words "from which" with "the", and replace "ore is
mined" with "zone" in sentence 2. This parenthetical
phrase should read "the matrix zone".
Insert the words "where present" in sentence 1.
Delete the last two sentences and replace with "The
matrix zone sometimes contains two layers of ore
separated by a layer of limestone. In this situation,
IMC mines both ore layers."
In sentence 2, Correct the depth of the surficial aquifer
system from 20 to 100 feet, replace the word
"limestone" with "matrix* in the second parenthetical
phrase, and correct the depth of the Floridan aquifer
from below 400 to below 200 feet.
Replace the word "high* with "elevated" in sentence 1 -
Add the sentence "According to IMC personnel, the
Gopher tortoise and Indigo snake are identified as
Species of Special Concern by the Florida Game and
Freshwater Fish Commission and have been observed
in the Four Corners Mine area." after the third
sentence.
Insert the word "currently" in the first sentence.
Replace the words "fine products" with "flotation feed"
in sentences 3 & 5. Add "course oversize" in sentence
3 to describe debris material.
Replace the words "initial removal" with "she clearing"
and add the words "initial removal of* in sentence 4.
Insert the word "alternately" and replace the word
"mill" with "plant" in sentence 6.
Insert the words "are set aside^ and replace the word
"mm" with "plant" in sentence's.--
Indicate the percent solids in the wells as "40-45 %"
in sentence 1. Replace the words "clay pond" with
"water recirculation" in sentence 2 to better describe
the water source.
Insert the word "recirculation" in sentence 2. Change
the flow rate from 1.800-2,000 to 18,000 to 20,000
gpm in sentence 4. Delete sentence 5, it is not
needed.
B-2
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Site Visit Report: IMC Four Corners
Page 14, Section 2.1, paragraph 6:
Page 14, Section 2.1, paragraph 7:
Page 14, Section 2.1, paragraph 8:
Page 14, Section 2.2. paragraph 1:
Page 15, Section 2.2.1, paragraph 1:
Page 15, Section 2.2.1, paragraph 2:
Page 15. Section 2.2.1, paragraph 3:
Replace the words "pit cars" with 'mine site" and
insert the word "washer" in sentence 1. Insert the
following after sentence 3, "Ditches and berms are
utilized selectively as required to prevent the off-site
drainage of slurried ore to adjacent wetlands or stream
systems due to gasket failures, pipeline breaks, etc.
This precautionary approach is used only when the
potential for off-site drainage exists which might
impact ecologically sensitive areas." Replace the word
"daily" with "hourly" in sentence 7. Insert the words
"and distance" and "up to" in sentence 8.
Replace the word "reduce" with "even out" in sentence
1.
Replace the word "moves" with "walks" in sentence 1.
Replace the word "with" with "using fill materials that
include" and insert the word "sand" in sentence 2.
Insert the words "County and State approved" in
sentence 3. Insert the words "a minimum of" in
sentence 4.
Replace the phrase "The matrix ore pipelines flow" with
"Matrix ore is transported through pipelines' in the first
sentence.
Replace the words "fine product" with "flotation feed"
in sentence 1.
Replace the word "at" with "of" in sentence 2.
Delete the entire paragraph (continues on page 17).
This process description is not accurate and should be
replaced with the following. "In each train, matrix ore
passes over a 20 foot long flat metal screen to
separate out material larger than 16 mesh (1 mm).
The material larger than 16 mesh goes to a trommel,
which is a rotating circular drum with "punch holes"
(openings). The first section of each trommel has 3/4
inch openings (to remove less jhan 3/4 inch material),
while the second section has 2.5 inch openings (to
remove greater that 3/4 inch and less than 2.5 inch
material). The material larger than 2.5 inch from the
trommel is classified as debris. Debris is disposed of in
the clay ponds or placed in an unlined onsite pile
located west of the beneficiation plant (the size of the
pile was not determined). Unspecified quantities of
debris are subsequently used on-site in reclamation or
road construction, or sold for off-site use. Materials
that are greater than 3/4 inch and less than 2.5 inches
are crushed in a hammer mill and sent back thru the
flat metal and trommel screens. The material passing
thru the 3/4 inch portion of the trommel passes over an
additional flat metal screen to remove some material
B-3
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Site Visit Report: IMC Four Corners
Page 16, Figure 5:
Page 17. Section 2.2.1, paragraph 4:
Page 17, Section 2.2.1, paragraph 5:
Page 17, Section 2.2.2:
Page 18, Section 2.2.2, paragraph 1:
Page 19, Section 2.2.2, paragraph 4:
passing 16 mesh. The oversize from this passes over
three vibrating screens. All three screens are
designated to separate the less than 3/4 inch material
into less than 16 mesh (flotation feed) and greater than
16 mesh (pebble product) material. The secondary
screen is a doubledeck screen, with the upper section
used to separate the material larger than 10 mm (3/8
inch) from the pebble product. According to IMC, the
greater than 3/8 inch material has a high MgO content.
It is classified as debris and managed with the other
debris materials described above."
Replace this figure with the revised Figure 5 (attached).
The original is not correct.
Replace the words "clay pond " with "water
recirculation* in sentence 2. Replace the word
"washes* with "washers11 in sentence 3. Replace the
word "wash" with "washer" in sentences 4 and 6.
Delete sentences 3 - 6 and replace with the following.
"The pebble product from the finishing screen is
conveyed to one of six pebble product bins. Water is
drained from these bins and directed to IMC's water
recirculation system. After assays are obtained for this
pebble, it is conveyed from the bin to an open heavy
media storage pile if MgO is greater than 1%, or if
MgO is less than 1 %, h is conveyed to open product
storage piles where it is stored by grade.
The stored product is conveyed from feeders located
beneath the open storage piles to railcar loading
facilities. Most of the product is sent to IMC's New
Wales Chemical Plant for processing, but some is also
sold to other customers."
Insert a note regarding this section, the Heavy Media
Separation Plant, stating This following section dealing
with IMC's Heavy Media Plant should to treated as
confidential". _
Replace the word "expanded" with "increased* and
"acreage" with "reserves* in sentence 4.
Delete this paragraph and replace with the following
"The pebble product from the heavy media separation
plant is conveyed to one of two pebble product bins
After assays are obtained for this heavy media product
the material is conveyed from the bin to open prodm i
storage piles where it is stockpiled according to grade
Most of the product is sent to IMC's New Wa-i
Chemical Plant for processing, but some is sold
B-4
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Site Visit Report: IMC Four Corners
Page 19. Section 2.2.2, paragraph 5:
Page 20. Section 2.2.3, paragraph 1:
Page 22, Section 2.2.3. paragraph 3:
Page 22, Section 2.2.3, paragraph 4:
Page 22. Section 2.2.3, paragraph 5:
Page 22, Section 2.2.3, paragraph 6:
Page 22, Section 2.2.3, paragraph 7:
Page 22, Section 2.2.3, paragraph 8:
Page 23, Section 2.2.3, paragraph 9:
Page 23, Section 2.2.3, paragraph 10:
other customers. Water is drained from the pebble
product bins and directed to the on-she water
recircuiation system."
Insert the word "media", and replace "oversized" with
"overflow" in the first sentence.
Replace the word "density" with "size" in sentence 3.
Correct the production numbers contained in sentence
5, (5.5 to 23, 3.9 to 16, 1.1 to 5, and 0.5 to 2).
Replace the time from "3-4 minutes" to "1 minute" in
sentence 3.
Delete the word 'Helical* in sentence 1. Replace the
word* "The overflow" with 'Materials left in the
trough" and "underflow* with "port" in sentence 2.
Replace the word "agitation" with 'supplied to
mechanical agitators" in sentence 3.
Replace the word "float* with "obtain" and add the
words "because of its lower feed grade (%BPL)W in
sentence 1. Replace the word "Denver" with
"Wemco" In sentence 3. Insert the words "Mechanical
agitators pull air thru* and delete "are used" in
sentence 4. Replace the words "0 size" with
"oversize" and "U size* with "undersize* in sentence 5.
Replace the words "0 size" with "oversize" in sentence
6. Replace the words "U size" with "undersize" in
sentence 7.
Replace the word "Denver" with "Wemco" in the first
sentence.
Insert the words 'water recircuiation' in sentence 7.
Replace the word "Denver* with 'Wemco" in
sentences 1 and 2.
Replace the word "remove" with "dewater" in sentence
3.
Delete the words "fine concentrate* in sentence 1
Delete sentences 2 and 3 and replace with "After
assays are obtained on the amine concentrate, the bin
is unloaded thru gates to conveyors which transport to
open product storage piles." Replace the wo>o
management" with 'recircuiation' in sentence >
Correct the percent moisture contents listed -
sentence 5 (change 7 to 8-10, and 10 to 7}. Dei*--*-
the last sentence of the paragraph.
B-5
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Sire Visit Report: IMC Four Corners
Page 23, Section 2.3, paragraph 1.1:
Page 23, Section 2.3, paragraph 1.2:
Page 23, Section 2.3, paragraph 1.3:
Page 24, Section 2.3, paragraph 1.4:
Page 24, Section 2.3, paragraph 1.5:
Page 24, Section 2.3, paragraph 2:
Page 24, Section 2.3, paragraph 3:
Page 25. Section 3.1, paragraph 1:
Insert the word "tank" in sentence 3. Insert the words
"with impervious floors" in sentence 4. Replace the
word "Statute" with "Chapter" in sentence 5. Replace
the word "statute" with "regulations" in sentence 6.
Replace the word "No" with "In addition" and insert the
word "occasionally" in sentence 8.
Replace "39,000" with "18,000" and the word
"aqueous" with "anhydrous" (two times) in sentence 1.
Replace the word "aqueous" with "anhydrous" and visa
versa and change "18,000" to "39,000" in sentence 2.
Add the following to the subparagraph, "It should be
noted that Four Comers has recently made a process
change from the use of aqueous ammonia to the use of
aqueous soda ash. Ammonia is no longer stored at
Four Comers as of October, 1992."
Insert the sizes of the three diesel tanks (19,800,
19,800, and 204.700) and delete the phrase "the sizes
of these tanks were not obtained" in sentence 1. In
sentence 2, indicate the size of the diesel tanks that
feed the amine process as 19,800 gallons and refer to
the tank that feeds the boiler as the "larger tank". Add
the sentence "Heating of the aqueous soda ash tanks
will be required during winter months." after sentence
3. Insert the words "with impervious floors" in the last
sentence.
Insert the words "with impervious floors" to sentence
2. Insert the following to the end of the subparagraph.
"Small spills have occurred in the past which tend to
etch the concrete secondary containment. Spills are
cleaned up as soon as discovered in accordance with
IMC's "Mineral Acid Storage Tank Containment and
Integrity Plan" which was prepared in October, 1992
pursuant to Chapter 17-767 - F.A.C."
Insert the words "with impervious floors"
sentence.
to the last
Replace the word "all* with "most" in sentence 1.
Replace "500" with "300-2.000* in sentence 2.
Replace the words "This storage area has" with "All
regulated tanks are located within" in sentence 3.
Replace the words "are located at the site for use" with
"would be obtained and used" in the last sentence.
Replace the words "dispose or with "store* in the first
sentence. Replace the word "wash" with "washer" in
sentences 5 and 8.
B-6
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Sire Visit Report: IMC Four Corners
Page 25, Section 3.1, paragraph 3:
Page 26, Table 2:
Page 26, Table 2:
Page 26, Table 2:
Page 28, Section 3.1, paragraph 4:
Page 28, Section 3.1, paragraph 5:
Page 29, Section 3.1, paragraph 6:
Page 29. Section 3.2, paragraph 1:
Insert the word "currently" in sentence 1. Replace the
phrase *20 foot thick" with "30 foot wide at top with
less than 2 1/2 to 1 side slopes" in sentence 2.
Replace the word "clay" with "soil" in sentence 7.
Replace the "State Department of Natural Resources"
with the "Florida State Department of Environmental
Regulation" in sentence 7. Replace the words
"previously mined" with "future mining" in sentence .8.
Note that this paragraph continues to page 28.
Dragline grease: change the quantity to 11,355
gallons/year hazardous and 0 gallons non-hazardous in
1991. Change the off-site TSD to Chemical
Conservation Corp. Add the sentence, "Non-hazardous
dragline grease would also be sent off-site to Chemical
Conservation Corp."
Spent Solvents: Indicate the listed quantities as 1991.
Laboratory Wastes: Indicate that none were generated
in 1991.
Replace the words "were not constructed with liners"
with "are constructed pursuant to Chapter 17-762,
F.A.C. requirements which do not require the use of
liners" in sentence 4. Replace the words "reclaimed
mining" with "previously mined" in sentence 5. Delete
"Hillsborough County' in sentence 8. Insert the
phrase "pursuant to Southwest Florida Water
Management District rules" in sentence 9. Replace the
word "mill" with "plant" in sentence 10.
Replace the word "reclaimed* with "decanted" in the
first sentence. Replace the words "small unlined pond"
with "return water ditch and is recycled in the plant.
Excess water flows to a small pond..." in sentence 7.
Insert "FDER/" in sentence 8. Add the phrase "and
entrapment in the settled clay" to the last sentence.
Insert the words "either required or* in sentence 7.
Insert the words "the" and "section" in sentence 8.
Replace the second "IMC* with "Four Comers", insert
the word "dry", and delete the phrase "no information
was available to indicate whether these quantities
represent wet or dry tailings" in sentence 1. Replace
the word "cannot" with "are not suitable" in sentence
2. Add the following after sentence 2, "DNR rules
require that tailings must be used on-site in dam
construction, and as fill material in reclamation.
B-7
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Site Visit Report: IMC Four Corners
Page 29, Section 3.2, paragraph 2;
Page 29. Section 3.2, paragraph 3:
Page 30, Section 3.2, paragraph 4:
Page 30, Section 3.4. paragraph 1:
Page 31, Section 3.5, paragraph 1:
Page 31, Section 3.6.1, paragraph 1:
Page 31, Section 3.6.2, paragraph 1:
Page 31, Section 3.6.3, paragraph 1:
Correct the dimensions of the tailings pile (5000 feet
long and 50 feet high) in sentence 4. Correct the
height from 100 feet to 50-60 feet in sentence 6.
Replace sentence 8 that states "In addition, no
information was obtained on the specific methods used
to construct either tailings pile." with "Tailings piles are
constructed by hydraulically pumping tailings with
slurry water. The water is recovered and returned to
the mine recirculation system for reuse."
Delete the words "within 24 months" in sentence 1.
Delete the word "However* from sentence 2. Add the
sentences, "This tailings pile is specifically being stored
for F3 construction. The DNR is aware of this plan and
has not indicated any problems." to the end of the
paragraph.
Replace "mg/l" with "ug/T in sentence 6. Replace
sentence 9 that states "Results of the verification
testing were not available at the time of the site visit."
with "The results of the resampling were below
detection limits." Insert the word "naturally" in
sentence 11.
Replace the words "clay pond water management
system" with "water recirculation system" in sentence
2. Insert the words "site , active mining and
reclamation areas, and clay settling ponds" in sentence
5.
Replace the words "clay pond" with "water
recirculation" in sentence 4.
Insert the phrase "or dedicated above ground waste oil
tanks" in the first sentence. Replace the word
"Corporation* with 'Service* and add "a division of
International Petroleum Corporation" in sentence 1.
Replace the word "returns" with "resells", add "to
them for reuse at", and replace "for" with "among
other locations* in sentence 2.
Insert the word "to* in sentence S.
Insert the word "lot" to sentence 5. Replace "1,355"
with "11.355", add the word "approximately", and
replace "Waste Management in Ohio" with
"Conservation Corporation in Orlando, FL, Valdosta,
GA, and Michigan" in sentence 6. Delete sentence 7.
Replace with "Waste grease that is determined to be
non-hazardous is handled and disposed of in the same
manner as the hazardous material. In 1992, 2,585
gallons of non-hazardous and 4,840 gallons of
B-8
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Site Visit Report: IMC Four Corners
Page 32, Section 3.6.4. paragraph 1:
Page 32, Section 3.6.4, paragraph 2:
Page 32, Section 3.6.5, paragraph 1:
Page 32, Section 3.6.6, paragraph 1:
Page 33, Section 3.6.9, paragraph 1:
Page 35, Section 4, paragraph 1:
Page 35, Section 4.1.1, paragraph 1:
Page 35, Section 4.1.1, paragraph 2;
Page 35, Section 4.1.1, paragraph 3:
Page 36, Section 4.1.1, paragraph 4:
Page 36, Section 4.1.1, paragraph 5:
hazardous grease had been shipped off site to Chemical
Conservation Corporation for proper disposal as of
August 20, 1992."
Replace the word "trichloroethylene" with
"tetrachloroethylene" in sentence 2. Insert the words
"supplied by" in sentence 3.
Insert the words "supplied by" In sentence 2.
Insert the words "If generated, hazardous", "would
be", replace "55-gallon* with "lab-pack", and add "for
proper disposal" in sentence 1. Replace sentence 2
with "No hazardous laboratory wastes were generated
in 1991.*
Insert the words "at approved facilities" in sentence 2.
Replace the words "day pond" with "water
recirculation/management" in sentence 5. (risen the
word "off-site" in sentence 6.
Insert the word "Polk" in sentence 2.
Insert the word "regional" and replace "District* with
"Bay Regional Planning Council" in sentence 4.
Replace "Planning District* with 'Regional Planning
Council" and add the words "coordinates interagency
review" in sentence 5.
Insert the phrase "which is stayed in effect pending the
settlement of contested requirements" in the last
sentence.
Replace the words "in the late seventies/early eighties"
with "on January 4, 1978" in sentence 1. Replace the
words "the remaining" with "an additional" and insert
the phrase "as well as the combining of previously
issued development orders" in sentence 6. Insert the
phrase "and areas adjacent to the mine* to the last
sentence of the paragraph on page 36.
Correct the spelling of "are* in sentence 2.
Insert the phrase "and are sampled semiannually" in the
first sentence. Replace the word "monitoring" with
"sampling" and indicate that monitoring is only done at
GDP-8 in sentence 2. Replace the word "mill" with
"plant" in sentence 3.
B-9
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Site Visit Report: IMC Four Corners
Page 36, Section 4.1.1, paragraph 6:
Page 36. Section 4,1,1 paragraph 6.1:
Page 36, Section 4.1.1 paragraph 6.2:
Page 38, Section 4.1.1 paragraph 6.3:
Page 38, Section 4.1.1 paragraph 6.4:
Page 38, Section 4.1.1, paragraph 7:
Page 38, Section 4.1.1, paragraph 8:
Replace the first two sentences with 'Surface water
monitoring is required quarterly at locations SW1,
SW2. SW3, and SW6 (monthly monitoring was
required at SW6 from October, 1991 to September,
1992). In addition, location SW 3 is required to be
sampled monthly each year from May to October.
Monitoring is required semiannually at locations SW4
and SW5. Monitoring is also performed quarterly at
location 302, the Little Manatee River prior to the
confluence with Alderman Creek.* Replace the word
"controlled* with "process impacted surface water"
and "surface waters* with "streams* in sentence 4.
Delete the words "As a result", insert the words "non
process related", and delete the phrase "(including
uncontrolled discharges of mine water and runoff)" in
sentence 5.
Insert the word "typically* in sentence 1.
Add the sentence "These levels may be attributable to
County Mosquito Control Activities." to the end of the
paragraph.
Add the sentence "Because radium is virtually insoluble
in the pH range from 2-10, it is likely that this finding
owes to inadvertently collected solids in the sample."
to tiie end of the paragraph.
Add the sentence "However, it should be pointed out
that black water rivers and streams which receive
heavy marsh water inflows, frequently exhibit low D.O.
levels naturally." to the end of the paragraph.
Insert the words "and/or ground water levels" in
sentence 1. Add the following after sentence 1, "Well
GD-6 is an alternate production well. The other listed
wells exist for water table monitoring." Replace the
word "flow" with "levels* in sentences 3 and 4.
Replace the words "flow is" with "levels are" in
sentence 5. __
Replace the word "ground" with "surficial", delete the
word "permanently", and add the words "due to mining
impacts" in sentence 1. Replace sentences 3 and 4
with "Recharge ditches, constructed according to
specifications established by site specific modeling
work, are used to prevent off-site groundwater level
drawdown. These ditches are maintained full of clear
water during mining and until reclamation has re-
established pre-existing conditions. Sub-surface
seepage from these ditches serves to maintain the
water table off-site."
B-10
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Site Visit Report: IMC Four Corners
Page 38, Section 4.1.1, paragraph 9:
Pao« 39, Section 4.1.2, paragraph 1:
Page 39, Section 4.1.2, paragraph 2:
Page 39. Section 4.1.3, paragraph 3:
Page 40, Section 4.2.1. paragraph 2:
Page 41, Section 4.2.1 paragraph 4.5:
Page 41, Section 4.2.1, paragraph 5:
Replace "S 10,000" with $5,700,000" in sentence 2.
Replace the word "incident" with "impairment" in the
last sentence.
Insert "F.A.C." to sentence 2. Insert the words "a
history of consistent" and "normally" in sentence 9.
Insert the words "and associated operations" in the last
sentence.
Insert the words "a minimum of" and replace
with "is" in sentence 2.
are-
Delete the words "for two years" in sentence 2.
Delete the words "however", "already", "at least', and
"completed", replace the word "completed" with
"initiated" and replace * 1993" with " 1994" in sentence
3.
Replace the words "approved by" with "designed and
supervised by" in sentence 2. Add the following
sentence after sentence 2, "All associated sampling
activities were conducted by a contract laboratory in
the presence of a DER observer." Insert the word
"pond" in sentence 3. Add the following sentence
after sentence 3, "The study was conducted prior to
mining activities at Four Corners." Add to the end of
the paragraph, "All Florida phosphate beneficiation
facilities employ an acid wash step, and all facilities
typically handle their associate wastewater fractions
via discharge to clay settling areas."
Replace the word "mill" with "sand" and insert "decant
water" in sentence 2.
Replace the word "mill" with "sand" and insert "decant
water" in sentence 2. Insert the following paragraph,
"It should be noted that IMC's surface water
management systems are currently fished both
commercially and for sport. A sustainable commercial
harvest of 25,000 pounds of fish per week is currently
taken from these areas. A spun, fisheries program is
currently managed by a private fishing club. The
competition for membership is fierce and poaching is a
consistent problem due to the prevalence of trophy
bass in waters found throughout IMC's respective
mines. This tremendous fisheries resource within the
active mine recirculation system is indication of the
high quality of our mine recirculating water systems.
Four Corners is no exception and currently retains a
fisheries biologist to control fish in the vicinity of its
plant area surface water pumping station. This is
required due to the damage that fish have caused to
the plant pumps in the past."
B-ll
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Site Visit Report: IMC Four Corners
Page 42, Section 4.2.2 paragraph 1.2:
Page 42. Section 4.2.3 paragraph 1.3:
Page 43. Table 4, Notes*:
Page 43, Table 4, Notes :
Page 44, Section 4.3.2, paragraph 1:
Page 46, Section 4.4, paragraph 1:
Page 46, Section 4.4, paragraph 3:
Page 47, Section 4.5, paragraph 1:
Page 47, Section 4.5, paragraph 2:
Page 47, Section 4.5, paragraph 3:
Page 47, Section 4.6.1, paragraph 1:
Replace the words "withdrawal rates* with 'water
levels" in sentence 1. Replace the words "measure the
potential for drawdown" with "evaluate drawdown
impacts" in sentence 4.
Replace the words "flotation process* with "circuits" in
sentence 1. Replace "Under IMC's County
Development Orders, GDP-7 and" with "As required by
the SWFWMD, well" in sentence 2. Replace the word
"seal" with "sealing" in sentence 3.
Change the first sentence to "The permit requires
weekly phosphorus analysis for monitoring purposes
only." Replace the word "the* with "a" and insert the
words "prepare a report that includes" in sentence 2.
Replace the word "discharge" with "availability of the
report for review'.
Change to indicate that un-ionized ammonia is
calculated using total ammonia, temperature, and pH.
Replace the word "only' with "solids", and add-the
word "are" in the sentence 4 parenthetical phrase.
Insert the word "to" in the last sentence.
Replace the word "all* with "most" in sentence 3.
Insert "or Manatee County" in the first sentence.
Replace the words "clay pond water management"
with ""water recirculation" in sentence 4. Replace the
word "seal" with "sealing" in sentences 5 and 8.
Replace the word "Planning" with "Water
Management" in the last sentence.
Insert the sentence "At SWFWMD's request, sampling
is performed at GDP-8 instead of GDP-7* after the first
sentence.
Replace '1991" with "1993" in sentence 1. Add the
following after the first sentence,-" A recent change in
SWFWMD's rules require facilities within a Water Use
Conservation Area (WUCA) to submit these reports by
July, 1992. Four Corners is located within a WUCA.
IMCF was not aware of this updated requirement until
September, 1992 (due to address errors in SWFWMD's
computer mailing list), and is currently in the process of
preparing the required report."
Replace the words "clay pond" with "mine water
recirculation" in sentence 2.
B-12
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Site Visit Report: IMC Four Corners
Page 47, Section 4.6.1. paragraph 2:
Page 49, Section 4.6.1, paragraph 3:
Page 51, Section 4.6.2, paragraph 2:
Page 51, Section 4.6.3, paragraph 1:
Page 51. Section 4.7, paragraph 1:
Replace the words "land applied on-site" with
"stabilized and land applied off-site be a qualified
licensed contractor.*
Delete the words "and" sewage sludge* in the first
sentence. Add "Sewage sludge test data are submitted
annually."
Delete the last sentence that states 'No further
information was found on any subsequent actions
taken by IMC or the Corps." Add the following, "This
matter has been settled with the Corps through
negotiations finalized in October, 1992. The disturbed
areas were permitted through Hillsborough County at
the time of mining and have since been permitted
through the Corps."
Insert the words "with impervious floors" in sentence
2.
Add the following sentences to the end of the
paragraph, 'Petroleum spills of less than 25 gallons do
not require regulatory notifications. This reporting
exception is stipulated in Chapter 17-762, F.A.C. - DER
rules."
B-13
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Site Visit Report: IMC Four Corners
APPENDIX C
EPA RESPONSE TO COMMENTS SUBMITTED BY IMC FERTILIZER, INC., ON DRAFT
SITE VISIT REPORT
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Site Visit Report: IMC Four Corners
EPA Response to Comments Submitted by
IMC Fertilizer, Inc.,
on Draft Site Visit Report
EPA has revised the report to incorporate all of the comments and suggestions made by IMC. In
some cases, EPA made minor changes to wording suggested by IMC in order to attribute the changes
to IMC or to enhance clarity. In response to IMC's comment and suggested language for the heavy
media section, EPA deleted much of the process description; this obviated the need to label the
section as "confidential".
C-l
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MINE SITE VISIT:
CYPRUS THOMPSON CREEK
June 1992
U.S. Environmental Protection Agency
Office of Solid Waste
Special Waste Branch
401 M Street, SW
Washington, DC 20460
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Site Visit Report: Cyprus Thompson Creek
DISCLAIMER
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 section of the Technical Resource Document consists of a report
on a site visit conducted by EPA to Cyprus Minerals Corporation's
Thompson Creek Molybdenum Mine near Challis, Idaho during 1991.
A draft of this report was provided to representatives of Cyprus
Minerals Corporation, the U.S. Forest Service, and the U.S. Bureau
of Land Management. Cyprus Minerals Corporation provided
comments, which are presented in Appendix B, The Forest Service
and the Bureau of Land Management did not provide comments.
EPA's responses to Cyprus' comments are summarized in Appendix
C.
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Site Visit Report: Cyprus Thompson Creek
TABLE OF CONTENTS
INTRODUCTION 1
Background 1
General Facility Description 2
Environmental Setting 4
FACILITY OPERATIONS 9
Mining Operations 9
Milling Operations 10
WASTE AND MATERIALS MANAGEMENT 13
Types of Waste and Materials 13
Waste Rock 13
Tailings 16
Mine Water 19
Other Materials and Wastes 19
REGULATORY REQUIREMENTS AND COMPLIANCE 22
Plan of Operations 22
NPDES Permit 28
Air Permit 29
Dam Safety Permit 29
Other Regulatory Requirements 30
REFERENCES 31
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Site Visit Report: Cyprus Thompson Creek
LIST OF TABLES
Table 1. Cyprus Thompson Creek Mining Company Daily Tailings and
Concentrate Composite Assays .x 16
Table 2. General Surface Water Parameter Concentrations for Pit Sump
(PIT 1, PIT 2, and PIT 3) 21
Table 3. Surface and Ground Water Monitoring Locations 24
Table 4. Bond Amounts Required of Cyprus Thompson Creek Through
December 31, 1993 25
LIST OF FIGURES
Figure 1. Location of Thompson Creek Molybdenum Project 3
Figure 2. Cyprus Thompson Creek Site Map 5
Figure 3. Cyprus Thompson Creek Mill Flow Chart 11
Figure 4. Surface and Ground Water Monitoring Locations 25
Figure 5. Monitoring Locations in Tailings Impoundment Area 26
in
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Site Visit Report: Cyprus Thompson Creek
INTRODUCTION
Background
EPA has initiated several information gathering activities to characterize mining wastes and waste
management practices. As part of these ongoing efforts, EPA is gathering data by conducting visits
to mine sites to study waste generation and management practices. As one of several site visits, EPA
visited Cyprus Minerals Corporation's Thompson Creek Mine near Challis, Idaho on August 28 and
29, 1991. This report discusses the extraction and beneficiation activities at the site.
The sites to be visited were selected by EPA to represent both an array of mining industry sectors and
different regional geographies. All site visits are conducted pursuant to the Resource Conservation
and Recovery Act (RCRA), Sections 3001 and 3007 information collection authorities. For those
sites located on Federal land, EPA has invited representatives of the appropriate land management
agency (U.S. Forest Service and Bureau of Land Management). State agency representatives and
EPA regional personnel also have been invited to participate in each site visit.
«
For each site, EPA has collected waste generation and management information using a three-step
approach: (1) contacting the facility by telephone to obtain initial information, (2) contacting state
regulatory agencies by telephone to obtain additional information, and (3) conducting the actual site
visit. Information collected prior to each visit is then reviewed and confirmed at the site.
The site visit reports describe mine operations, mine waste generation and management practices, and
the regulatory status on a site-specific basis; the information is based on information gathered from
State and Federal agency files as well as observations made during the site visit. In preparing this
report, EPA collected information from a variety of sources, including the Cyprus Thompson Creek
facility, the Idaho Department of Lands (IDL), the U.S. Forest Service (USFS), and other published
information. The following individuals participated in the Cyprus Thompson Creek site visit on
August 28 and 29, 1991.
Cyprus Minerals Corporation
Les Darling, Director, Environmental Affairs (303) 643-5325
Cyprus Copper Company
Jamie Sturgess, Manager, Environmental Affairs (303) 643-5782
Cyprus Thompson Creek
Bert Doughty, Supervisor, Environmental Affairs (208) 838-2200
Don Hilleary, Chief Engineer
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Site Visit Report: Cyprus Thompson Creek
Jim Kopp, Operations Supervisor
Marvin Harmer, Chief Metallurgist
Turk Terrill, Mine Superintendent
U.S. EPA
Van Housman, Chemical Engineer
Science Applications International Corporation
Ingrid Rosencrantz, Environmental Scientist
Ron Rimelman, Chemical Engineer
U.S. Forest Service
Greg Johnson
Pete Peters
U.S. Bureau of Land Management
Dan Bartholme
(703) 308-8419
(703) 734-2508
(703) 821-4861
(208) 838-2201
(208) 838-2201
(208) 756-5400
General Facility Description
Cyprus Minerals Corporation (Cyprus) mines molybdenite (molybdenum disulfide, MoS^ from an
open pit mine near Challis in central Idaho (see Figure 1). The mine site is located in an area of high
mountain ranges, and numerous lakes, streams, and valleys near the Salmon River and its tributaries,
which flow through the lower elevations. Elevations range from 5,500 feet at the Salmon River to
9,487 feet near the mine site. The active facility is located on nearly 1,935 acres of mixed ownership
including: private lands (521 acres), Bureau of Land Management (BLM) administered Federal land
(781 acres), and USFS administered Federal land (633 acres of the Challis National Forest). Cyprus
also controls a mineral claim block of about 16,000 acres around the Thompson Creek Mine.
The mine is located in Custer County, approximately 35 miles southwest of Challis, the county seat of
Custer County. The nearest town is Clayton, which has a population of 42 and is approximately 12
miles from the site. Access to the mine site is from State Highway 75, along an unpaved county road
that generally parallels Squaw Creek. The road crosses Squaw Creek, first west to east about 1.5
miles from its intersection with State Highway 75 and from east to west about 4 miles from the
intersection.
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Site Visit Report: Cyprus Thompson Creek
Figure 1: Location of Thompson Creek Molybdenum Project
(Source: USFS 1980)
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Site Visit Report: Cyprus Thompson Creek
Several historic mining operations are located in the vicinity of the Cyprus Thompson Creek site. An
old tungsten mine is buried under the Buckskin waste rock dump. The remains of the mill associated
with this mine are located along Thompson Creek downstream of the site (see later discussion of
ongoing joint Cyprus/USFS remediation activities on tailings generated by the mill). A small gold
mine (circa 1929) was located north of the tailings pond (not on Cyprus property). Finally, an old
silver/zinc mine (1930s-1940s) was operated in the area (also not on the Cyprus property).
Cyprus staked its first mineral claims at Thompson Creek in 1967. During 1974 and 1975, a
preliminary feasibility study for a large open pit and concentrator was prepared. Based on the results
of this study, Cyprus Minerals initiated additional technical studies to better define the potential
project. On May 25, 1979, Cyprus Minerals submitted its Notice of Intent to Operate and Initial Plan
of Operations to the Challis National Forest. In 1981, mining operations began and the first
concentrates were produced in 1983.
The Cyprus Thompson Creek Mine site currently consists of (1) an open pit mine and two associated
waste rock dumps; (2) a primary in-pit crusher; (3) a mill that includes grinding and concentration by
flotation, and (4) a tailings impoundment. These units, as well as various support and maintenance
facilities, are shown in Figure 2. During the site visit, the facility was only conducting stripping
operations (i.e., removing overburden and waste rock to access the orebody). As a result, the mill
was temporarily inactive.
Environmental Setting
Climate. The Thompson Creek Project is located in a fairly rugged mountainous region of central
Idaho. This region is west of the Continental Divide and approximately 525 miles east of the Pacific
Ocean. The prevailing air flow over the local area near the project is from the west; however, local
topographic features considerably influence surface wind velocity and direction. The canyons and
ridges probably cause channeling and lee eddies. The maximum sustained wind velocity recorded by
an on-site weather station (in operation since 1972) has been 15 mph. Wind gusts have not been
measured; however, strong gusts estimated to be in the range of 40-60 mph have occurred. On-site
wind direction tends to be north-south approximately 50 percent of the time and variable the
remainder of the time. The average annual precipitation at the project site is estimated to be 10 to 20
inches or greater, depending on the altitude. The maximum and minimum recorded temperatures
have been 93°F and -25°F, respectively (USFS 1980).
Surface Water. The mine site is located in the drainage systems of Bruno Creek, Thompson Creek,
Squaw Creek, Buckskin Creek, and Pat Hughes Creek, all of which are tributaries of the Salmon
River. The waste rock dumps overlie Buckskin Creek and Pat Hughes Creek, which flow into
Thompson Creek. Cyprus' tailings impoundment overlies Bruno Creek, which can be diverted
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Site Visit Report: Cyprus Thompson Creek
Figure 2: Cyprus Thompson Creek Site Map
(Source: Cyprus, provided at .Site Visit)
1
Figure 2: Cyprus Thompson Creek Site Map
(Source: Cypru*. provided at Site Visit)
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Site Visit Report: Cyprus Thompson Creek
around the impoundment, as necessary. Bruno Creek feeds Squaw Creek. Both Thompson Creek
and Squaw Creek flow directly into the Salmon River, approximately five miles from the site. All of
these waterbodies are classified by the State as Class II waters and must be protected for the following
general uses: (1) agricultural water supply, (2) cold water biota, (3) salmonid spawning, and (4)
secondary contact recreation (State of Idaho 1989). In addition, the Salmon River downstream of the
facility is further designated as a domestic water supply and for primary contact recreation. The
Salmon River south of the mine site is designated as a Special Resource Water, because of salmonid
spawning grounds. According to Cyprus personnel, surface water in the vicinity of the facility is
only used as a drinking water supply for animals on nearby ranches. In addition, Cyprus obtains
makeup water from the Salmon River for use in the mill (when the mill is operating).
Geology. The bedrock geology of the region is a sequence of Paleozoic sedimentary rocks intruded
by Cretaceous igneous rocks known as the Idaho batholith. A large portion of the area is overlain by
a series of Tertiary volcanic rocks called the Challis volcanics (USFS 1980).
The Paleozoic sedimentary rocks range in age from the Cambrian to Pennsylvanian geologic periods,
and vary in sequences of argillite, quartzite, limestone, dolomite, and shale, some several thousand
feet thick. The primary sedimentary rocks from the oldest to youngest are the Saturday Mountain,
Copper Basin, and Wood River formations. These sedimentary rocks have been intruded by a biotite
granodiorite-quartz monzonite stock known as the Idaho batholith. In some areas of intrusion, contact
metamorphism has occurred, creating silicification and hornfelsing of the argillite. Intrusive rocks
can be exposed on the ground surface at the mine site but are generally overlain with volcanics at the
site (USFS 1980).
Complex folding and faulting exists in the Paleozoic sedimentary units of the claim area. A thrust
fault is thought to exist near Bruno Creek. The thrust plane is at a low angle and the effect has been
to thrust younger Mississippian rocks on top of the older Ordovician sequence at this location. A
variety of other faults including bedding plane slippage have been noted in the Bruno Creek area.
The age of folding and faulting in the project area remains uncertain. The deformation clearly took
place before the extrusion of the Challis volcanics (38-49 million years) and may have been completed
by stresses related to the intrusion of the nearby plutonic rocks during mid-Cretaceous time (85-100
million years). There is no known evidence to indicate that faults in this area have been recently
active (no specific timeframes were provided in the reference) (USFS 1980).
The site is located in the USGS Class n Intermountain Seismic Zone. In the vicinity of the mine site,
there were a total of 56 earthquakes from 1935 to 1980 with Richter magnitudes of 4.0 or greater.
The majority of earthquake epicenters in the study area are located about 12 miles west of the project
area. This region of seismic activity is referred to as the Sunbeam District. There are, however, no
major faults within 12 miles of the project area. Therefore, it is unlikely that a fault structure exists
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Site Visit Report: Cyprus Thompson Creek
in the project vicinity that could produce an earthquake event exceeding a 7.6 magnitude (USFS
1980).
Of particular note, in 1983, a major earthquake (7.3 on the Richter scale) was centered approximately
40 miles from the mine site. This earthquake caused property damage and two fatalities in Challis.
Cyprus personnel who were present at the site at that time noted severe tremors in the vicinity of the
tailings impoundment.
Hydrogeology. The occurrence and distribution of ground water within the project area is determined
by the complex hydrogeology of the region. The area is mountainous with steep slopes along
drainages. The primary sources of ground water include: (1) infiltration of runoff into surface soils,
(2) stream channel underflow within alluvial deposits, and (3) water in fracture and fault zones of
bedrock formations.
Relatively small quantities of ground water are contained within the surface soils and decomposed
bedrock comprising the soil mantle. Alluvial deposits occur in stream channel bottoms; ground water
in the alluvium is in direct connection with surface water within the stream courses. The major
stream channels in the project area are Squaw and Thompson Creeks, which are tributaries of the
Salmon River. The direction of surface water flow is generally to the south. The mine site is
characterized by narrow, steep-sided and v-shaped valleys. Based on existing information, alluvial
deposits are probably less than 100 feet in thickness and 300 feet in width along the stream courses
(USFS 1980). According to Cyprus, an alluvial aquifer is found at depths ranging from 0 to 20 feet
below ground in the vicinity of the creekbeds.
Argillaceous sediments of the Copper Basin and Saturday Mountain formations are the primary
sedimentary bedrock aquifers in the mine site area. The lithology of these units is largely argillite,
bedded limestones, and dolomite. The well-consolidated, and hi some locations metamorphosed,
nature of these rocks creates low porosity, preventing the production of significant amounts of ground
water from pore spaces. However, these formations are extremely folded and at some locations are
nearly vertical (USFS 1980).
In general, there is a continuous supply of baseflow to the streams throughout the year from the
alluvial and bedrock aquifers. Larger quantities of baseflow occur during periods of high
precipitation and snow melt; however, this contributes a smaller percentage to total surface water
runoff. Baseflow may constitute 90 percent or more of the total stream flow during dry periods of
the year (USFS 1980).
The shallow alluvial aquifer is used for livestock drinking water on nearby ranches. The uppermost
bedrock aquifer is encountered at a depth of 150 feet. Cyprus has two potable water wells on the site
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Site Visit Report: Cyprus Thompson Creek
at a depth of 250 feet. These wells are approximately one mile apart and produce 15 and 20-25
gallons per minute (gpm), respectively. According to Cyprus personnel, there are no other uses of
the aquifers in the immediate vicinity of the site. Other than the on-site wells, the nearest drinking
water well is at the Red Bird Mine three miles from the mine site.
Air Quality. The mine site is located in an undeveloped area in Custer County, Idaho. The air
quality at the site is characterized as excellent because of the remoteness of the area and the absence
of sources of pollutant emissions. There are no ambient air quality monitoring stations in the vicinity
of the mine site. However, the baseline air quality was expected to be typical of a remote area. The
primary pollutant was expected to be total suspended particulates because of mining operations.
Hydrocarbons, carbon monoxide, and nitrogen oxides would not be expected to be appreciable
because of the lack of significant motor vehicle traffic (USFS 1980).
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Site Visit Report: Cyprus Thompson Creek
FACILITY OPERATIONS
Cyprus staked its first mineral claims at Thompson Creek in 1967. Prior to the commencement of
mining operations, Cyprus drilled more than 160,000 feet of exploration holes from surface and
underground locations and outlined a significant molybdenum deposit containing at least 200 million
tons of ore averaging 0.18 percent molybdenite (MoSj) (USFS 1980). Mining began in 1981 and the
first concentrates were produced from the mill in 1983. In 1986, the mill was shutdown for one
month. The mill was also inactive from October 1987 to March 1988, when only minor stripping
operations (i.e., removal of overburden and waste rock) were underway. At the time of the site visit,
the mill was inactive, although waste rock and overburden stripping operations in the mine continued
to access additional ore. (According to Cyprus, milling operations resumed after the site visit in
November 1991.) Assuming continuous operation of the mine and mill, the operation was originally
planned to be active for 20 years. With the periods of inactivity discussed above, the operation has
approximately 13 years from the date of the site visit of operation remaining.
Mining Operations
Along a ridge in the Salmon Mountains, Cyprus operates a large open pit where molybdenite (MoS2)
ore is mined from quartz monzonite. The top of the open pit is at an elevation of approximately
8,400 feet above sea level with the orebody encountered at 7,300-7,400 feet (or at a depth of
approximately 1,000 feet). The pit currently extends down to the 7,050 foot level, with plans to
expand down to an elevation of 6,400 feet (i.e., to a depth of 2,000 feet). The mine operates
continuously 24 hours per day, seven days per week, 365 days per year.
When mining began in 1981, approximately 130 million tons of overburden were initially removed as
"preproduction stripping" concurrent with the construction of project facilities. Most of the
overburden was placed in the two waste rock dumps (the Buckskin and Pat Hughes dumps) located
adjacent to the pit, although some overburden was used as fill for construction purposes (USFS 1980).
Mining operations generally follow those described in the 1982 Plan of Operations approved by
USFS. The ore is accessed by drilling and blasting along 50 foot benches. Drilling is accomplished
using Marian electric drills and a typical blast pattern consists of between 30-40 holes. ANFO, a
blend of ammonium nitrate and diesel fuel, is used as the blasting agent (10,000 tons of ANFO are
used annually). Waste oil has previously been substituted for diesel fuel in the ANFO mixture,
however, it is not being used pending MSHA approval. On average, one blast occurs every other
day. After fragmentation, ore and waste rock are excavated using P & H electric shovels. Cyprus
has two 28 cubic yard shovels, one 17 cubic yard shovel, and two 15 cubic yard shovels. The
shovels place the ore and waste rock in 170 ton diesel haul trucks. The ore is then transported to the
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Site Visit Report: Cyprus Thompson Creek
primary crusher, while the waste rock goes to either the Buckskin or Pat Hughes dump. Information
on the specific cutoff grade between waste rock and ore was not obtained.
In 1990, approximately 16.2 million cubic yards of waste rock and 4.5 million tons or ore were
generated, a stripping ratio of 4:1 (waste rock:ore). However, over the life of the mine, Cyprus
personnel indicated that the average stripping ratio would be closer to 2:1. At the tune of the site
visit, Cyprus was stripping away waste rock to access additional areas of the orebody and the mill
was inactive. As a result, only waste rock was being generated and disposed of.
Milling Operations
A flow diagram of the milling operations at the site is presented in Figure 3. Mined ore is first sent
through a 60 x 89 inch gyratory primary crusher located near the mine, where the ore is crushed to
minus 8 inches. The gyratory crusher is equipped with a baghouse for paniculate emissions control.
From the primary crusher, the ore is transported by conveyor to a surge pile, located near the mill.
The conveyor belt is 2,350 feet long and 60 inches wide. The surge pile contains approximately
300,000 tons of ore. However, Cyprus personnel indicated that only 75,000 tons of ore comprise the
"active" portion of the pile. The remainder of the ore in the pile is stored semi-permanently for
beneficiation if conveyor problems disrupt the feed to the pile. Ore is removed from the surge pile
by 8 feeders underneath the pile. The ore is then transported to two parallel grinding circuits. In
each circuit, the ore initially enters a 32 foot diameter semi-autogenous grinding (SAG) mill. The
outputs from the SAG mills are passed over 0.75 inch screens and flow into cyclone separators. The
overflows from the cyclones go directly to flotation, while the underflows go to 16.5 foot by 26 foot
ball mills for further grinding prior to flotation. Grinding is a wet process and burned lime is added
for pH control. In 1990, Cyprus used an average of 0.132 pounds of lime per ton of ore. The
grinding circuit product is 35 percent solids.
In the flotation process, the slurry from the grinding circuits is passed into flotation cells (or tanks).
Flotation is accomplished by bubbling air through the slurry in a series of mechanically agitated cells.
Fuel oil is used as the collector, alcohol is used as the frother, and a Nokes reagent (P2S5 and NaOH)
is added in the cleaner stages to depress copper and lead. In 1990, Cyprus used an average of 0.117
pounds of fuel oil, 0.025 pounds of alcohol, and 0.011 pounds of Nokes reagent per ton of ore. No
cyanide is used in the process. The flotation operation is conducted in several stages (rougher and
cleaner). The first rougher stage produces concentrate overflow (approximately 10 percent
molybdenum disulfide) that is then reground in a small ball mill. The underflow from the first
rougher stage goes directly to the tailings impoundment by pipeline. The effluent from the small ball
mill is then subjected to ten additional stages of flotation, called "cleaner" stages, to progressively
10
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Site Visit Report: Cyprus Thompson Creek
Figure 3: Cyprus Thompson Creek Mill Flow Chart
f\^ TO null »«»» CI«CVIT
9 r
TAILS
(Source: Cyprus, provided during site visit)
11
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Site Visit Report: Cyprus Thompson Creek
upgrade the concentrate. The overflow from each successive cleaner stage flows to the next cleaner
stage. The underflow from the first of the ten cleaner stages (identified by Cyprus as "scavenger"
flotation) goes directly to the tailings impoundment. The underflows from subsequent cleaner stages
are returned to first cleaner/scavenger stage. The final cleaner cells produce crystalline MoS2
concentrate. The MoS2 crystals are passed over a screen. The smaller, lower grade particles from
cleaner flotation are sent to a holoflyte dryer/"screw conveyor." Heated oil is circulated through the
hollow sections of the screw conveyor to provide enough heat to evaporate additional water in the
concentrate. The dried concentrate (identified by Cyprus as technical grade concentrate) is 54 to 59
percent molybdenum disulfide with less than 9.0 percent water and 1.0 percent fuel oil. The technical
grade concentrate is packaged in 4,000 pound bags and sent by truck to deep water ports or the
Cyprus Sierrita facility in Arizona for roasting.
Depending on market conditions, the larger, higher grade particles (those that do not pass through the
screen) are either sent to drying and packaging or to Cyprus' High Performance Molybdenum (HPM)
plant. In the HPM plant, the crystals are reground and then subjected to either one or two stages of
column flotation, again depending upon market requirements. The concentrate, which is 15-18
percent water, is then passed through a filter plate. The filtrate is recycled as process water. The
filtered crystals are sent to a separate holoflyte dryer/screw conveyor in the HPM plant.
The dried HPM concentrate is a very fine powder, about 59 percent molybdenum disulfide with less
than one percent water and 0.1 percent fuel oil. The HPM concentrate is packaged in S
drums or other suitable containers for shipment off-site as product.
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Site Visit Report: Cyprus Thompson Creek
WASTE AND MATERIALS MANAGEMENT
Types of Waste and Materials
This section describes several of the wastes and materials that are generated and/or managed at the
Cyprus Thompson Creek facility and the means by which they are managed. It should be noted that a
variety of wastes and other materials are generated and managed by molybdenum extraction and
beneficiation 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 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.
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 following subsections describe 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. Wastes and materials generated at Cyprus Thompson Creek include waste
rock, tailings, mine water, and other wastes and materials (e.g., waste oil, grease, spent solvents,
sanitary waste, capacitors, and haul road runoff).
Waste Rock
As noted in the previous chapter, approximately 16.2 million cubic yards of waste rock were
generated in 1990. During the site visit, when only accelerated stripping operations were underway,
Cyprus was generating approximately 2 million cubic yards of waste rock per month. Four types of
materials are found in the waste rock. These materials include: metasediment, quartz monzonite,
challis volcanics, and clayey rock (i.e., decomposed volcanics). Waste rock is initially classified and
segregated by type of material. Types of waste rock are then separately end-dumped in the two on-
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Site Visit Report: Cyprus Thompson Creek
site waste rock dumps, the Buckskin and Pat Hughes waste dumps (named to correspond with the
drainages in which they are located). Cyprus currently determines where to place specific types of
materials based on stability requirements (see discussion of stability issues below).
The Buckskin dump is considerably larger than the Pat Hughes dump and designed to contain 480
million tons of waste material. No information was obtained for the Buckskin dump on the annual
quantity of waste rock disposed or the total amount of material currently contained hi the dump. The
slope of the Buckskin dump is at the angle of repose of the waste rock (slopes range from 33° to 38°).
The dump at the time of the site visit was 1,300 feet high extending from an elevation of 8,100 feet
to 6,800 feet. Two 300-foot-wide benches, which enhance stability, are currently situated at the
7,600 foot and 7,900 foot levels, respectively. The maximum depth of material in the dump is
planned to be approximately 950 feet (Colder Associates 1980).
The Pat Hughes dump is designed to contain approximately 130 million tons of waste material. No
information was obtained for the Pat Hughes dump on the annual quantity of waste rock disposed or
the total amount of material currently contained in the dump. The waste material has been placed in
the dump progressively from north to south. The slope of the Pat Hughes dump is also at the angle
of repose of the waste rock with slopes ranging from 33° to 38°. The dump at the time of the site
visit was 800 feet high and will eventually extend from 7,150 to the toe of the dump at elevation
6,300. The maximum depth of material in the dump is planned to be 700 feet (Golder Associates
1980).
In September 1984, the first documented failure of waste rock in the Buckskin dump occurred. The
failure involved several hundred feet of slope crest, with a 100 foot wide section sliding up to 100
feet. It was reported that a reason for the failure was excessive dumping of volcanic rock (> 100
million cubic yards) between August and mid-September of 1984. Following the dump failure,
relatively little waste material was disposed of between October 1984 and June 1986. However, in
July 1986, dumping commenced from the 7,750 level. As a result of the continued dumping, the
dump again failed on November 11, 1986. A section approximately 80 to 90 feet high along a crest
length of 800 to 900 feet failed. Cyprus soon started dumping again but at a different location in the
dump. A third large failure occurred on August 27, 1988, which raised serious concerns of the
dump's stability (Piteau Associates 1989).
To address these stability problems, Cyprus modified its waste rock dumping practices and began
segregating materials. The facility now tries to place the quartz monzonite (intrusive rock) on the
outer surfaces of the dumps to "armor" the faces and increase stability.
Facility personnel indicated that the intrusive rocks have high sulfur content (up to 1.13 percent).
Therefore, since 1990, Cyprus has been conducting a study of the potential for acid rock drainage
14
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Site Visit Report: Cyprus Thompson Creek
(ARD) generation from the waste rock and tailings. (For a more complete discussion of ARD, see
U.S. EPA Office of Solid Waste, 1994, Acid Mine Drainage Prediction.) According to USFS
personnel, the Thompson Creek mine is the only active mine in the area that has had to address ARD
rock generation. Static testing has been performed on eight intrusive rock samples collected from the
lower benches of the pit. For each sample, Cyprus determined the net neutralization potential (NNP)
and the neutralization potential/acid generation potential (NP/AP) ratio. The NNP represents the
neutralization potential (the tons of calcium carbonate required to neutralize 1,000 tons of waste rock)
minus acid generation potential (calculated based on the total sulfur content). Analyses of the eight
samples showed an average NNP of 0.053 with values ranging from -6.26 to 7.31. The NP/AP ratio
for these samples was 1.88:1 with values ranging from 0.63:1 to 6.85:1. According to Cyprus
personnel, waste rock with an NP/AP ratio in excess of 3:1 may be considered non-acid generating
(Steffen Robertson & Kirsten 1991a). According to USFS personnel, a NP/AP ratio of at least 5:1
should be required before a material is determined to be non-acid forming. Thirteen samples of
intrusive rock collected from the upper benches of the pit showed an average NNP of 4.93 with
values ranging from -0.65 to 11.35, and an average NP/AP ratio of 3.80:1 with values ranging from
0.90:1 to 15.92:1. The difference between intrusive rock samples collected from the upper and lower
benches is believed to be caused by a relatively predictable pattern of mineralization and alteration
zoning about the ore, body. According to Cyprus, the metasedimentary and volcanic rocks do not
appear to be sources of ARD. Cyprus has performed static testing on the metasedimentary rock and
found average NNP and NP/AP values of 24.95 and 3.11:1, respectively (Steffen Robertson &
Kirsten 1991a). It should be noted that, while the metasedimentary rocks are considered non-acid
forming by Cyprus (NP/AP greater than 3:1), the average NP/AP ratio is less than the minimum ratio
suggested by the USFS (5:1). According to Cyprus, seventy-six samples of the volcanic rocks have
also been analyzed for acid base accounting. All samples showed NP/AP ratios of greater than 31:1.
Prior to commencement of dumping in 1981, Cyprus installed a culvert and drain system in both
valley bottoms to convey the creeks underneath the dumps. The underdrain systems are further
designed to collect infiltration through dump materials. These systems drain into sediment ponds,
which also collect surface runoff from the dump areas. The sediments ponds discharge through
NPDES outfalls to Buckskin andTPat Hughes Creeks. The discharge from the Buckskin dump
sediment pond is identified as National Pollutant Discharge Elimination System (NPDES) outfall 001,
while the discharge from the Pat Hughes dump sediment pond is NPDES outfall 002. During 1989-
1990, pH levels in the discharges from outfalls 001 and 002 ranged from 7.0 to 9.2 s.u. and 6.4 to
8.9, respectively. (A complete summary of monitoring results for outfalls 001 and 002 is included in
Appendix A) (Cyprus 1991a). As indicated by Cyprus personnel, no evidence of ARD has yet been
found in these discharges. A NALCO coagulant is added to the sediment ponds during the spring to
help control total suspended solids levels in the discharges (the amount of coagulant added was not
obtained). According to Cyprus personnel, no other treatment is required to meet NPDES permit
limits.
15
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Site Visit Report: Cyprus Thompson Creek
Tailings
When the mill is operating at full production, tailings are generated at a rate of approximately 7.5
million cubic yards per year. On Cyprus' 10/4 mill operating schedule (10 consecutive days
operating/4 days shutdown), about 5.5 million cubic yards of tailings are produced each year. Cyprus
continuously monitors the composition of concentrates and tailings generated by each flotation stage to
assess mill performance. Samples are collected every 15 minutes and composited for analysis every
24 hours. The results of one recent analysis of a 24-hour composite sample are presented in Table 1.
As indicated in the previous section, only the rougher and scavenger tails are sent to the tailings
impoundment.
Table 1: Cyprus Thompson Creek Mining Company
Daily Tailings and Concentrate Composite Assays
Report Date: 28/Jan/91
Sample
Rougher Tails
Combined Tails
Scavenger Tails
Rougher Concentrate
1st Cleaner Concentrate
2nd Cleaner Tails
Molybdenum
Percent
0.009
0.009
0.073
8.11
43.40
34.10
Copper
Percent
0.002
0.004
0.150
0.130
0.620
1.300
Lead
Percent
0.002
0.003
0.051
0.060
0.180
0.240
Tailings flow from the mill in a 30-inch diameter high density polyethylene (HOPE) pipeline that
extends 7,000 feet north-northeast to the tailings impoundment in the Bruno Creek drainage. The
tailings discharged from the mill are approximately 39 percent solids and the pipeline flow is about
10,000 gpm. The pipeline is situated in an unlined ditch along its entire length to provide for
secondary containment.
The tailings impoundment covers a total of approximately 150 acres with the embankment covering
about 60-70 acres and the tailings pond behind the embankment approximately 90 acres. The
embankment is currently about 400 feet high with an eventual planned final height of 600 feet. The
impoundment is designed to contain the surface water runoff from a 500-year storm event. In
addition, the impoundment was designed with a runoff interceptor system (SIS). When Cyprus
16
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Site Visit Report: Cyprus Thompson Creek
determines that it is necessary to reduce the upstream flow of Bruno Creek into the tailings
impoundment, the RIS can be used to divert Bruno Creek around the impoundment. The diverted
flow is discharged to lower Bruno Creek below the final seepage collection sump described below.
The "centerline" method is the chosen technique for tailings embankment construction. The starter
dam was a 35-foot earthen embankment. Tailings fractions are classified by cycloning (as sands or
slimes) and distributed to the impoundment by spigotting. The coarse fraction (sands) forms the
embankment that retains the slimes. The slimes have formed a "beach" that slopes upstream away
from the embankment. Tailings water is kept at the upstream end of the impoundment by the addition
of tailings to the upstream face of the dam. Eighty percent of the tailings water is reclaimed by a
pumping barge and reused in the mill. The flow of reclaim water to the mill averages 7,000 gallons
per minute (gpm). Additional fresh water may be pumped from the Salmon River as needed (this is
not continuous, but typically averages 1,000 gpm). Under their water quality monitoring program,
Cyprus collects and analyzes tailings pond water at the inflow to the barge pump. At the time of the
site visit, Cyprus personnel indicated that the pH of the tailings water was 6.5 to 7.0 s.u. Results of
analyses for 1989-1990 are included in Appendix A (see monitoring location TP).
Consolidation of the tailings in the impoundment is promoted by controlled seepage through the dam.
Piezometers and open-ended standpipes are used to monitor stability in the impoundment. French
drains located under and within the impoundment direct the flow of seepage through the permeable
embankment.
The tailings disposal system has been designed to be a zero discharge unit. A seepage return pond
was constructed below the embankment to collect the seepage from the tailings impoundment. The
clay-lined seepage pond typically contains approximately 20 acre feet of seepage with the capacity to
contain up to 100 acre feet (the current area and depth of the pond, and average seepage rates were
not determined). The downstream end of the return pond (approximately 850 feet from the tailings
embankment) is an earth and rock fill dam, identified by Cyprus as the Seepage Return Dam (SRD).
The maximum height of the SRD is 75 feet with an impervious upstream zone and a rock fill
downstream zone. The SRD incorporates a positive seepage cutoff by use of a grout curtain in the
foundation bedrock. At the time of the site visit, the pH of seepage pond water was 6.2 to 6.5 s.u.
While the SRD was originally planned to contain all seepage from the tailings impoundment, Cyprus
personnel subsequently identified seepage downstream of the SRD. Therefore, to ensure no discharge
of seepage to Bruno Creek, a lined sump was installed further downstream in Bruno Creek drainage
(information on the specific type of liner was not obtained). Under their water quality monitoring
program, Cyprus collects and analyzes samples from the inlet to this sump. Results of analyses for
1989-1990 are included in Appendix A (see monitoring location PBS). Seepage collected in both the
seepage return pond and the downstream sump is pumped back to the mill for reuse. In 1990, the
17
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Site Visit Report: Cyprus Thompson Creek
monthly average pumping rate from the return pond to the mill ranged from 791 gpm (August) to
1352 gpm (November and December) (Cyprus 1991b). The quantity of seepage returned to the mill
from the sump was not obtained.
During the ongoing acid drainage study, indications of acid generation have been found in the
tailings. According to Cyprus personnel, tailings oxidation has been evident for over two years. In
October 1990, ten hollow stem auger borings were completed in the tailings embankment. Samples
collected from the these borings showed that the average sulfur content of the tailings sands was 0.79
percent and the pH ranged from 3.5 to 7.3 s.u. (Steffen Robertson & Kirsten 1991b). During the site
visit, Cyprus personnel further indicated that analyses of tailings sands have shown pH levels as low
as 3.0 s.u. According to Cyprus personnel, the tailings pond and the seepage return pond are not
currently a problem (pH > 5.7 s.u.). However, in 1991, Cyprus conducted a water quality trend
analysis for six surface water quality monitoring locations in the tailings impoundment area. These
locations included the main drain of the rock toe, springs located on the left and right abutments of
the rock toe, the discharge from the rock toe, the sump below the SRD, and Bruno Creek
(immediately downstream of the sump). This analysis found that during the period 1981-1990, pH
decreased at four locations (not at the left and right abutment springs), (2) sulfate had increased at all
locations, (3) iron had increased at four locations (not at the left and right abutment springs), and (4)
no trends in zinc, copper, or arsenic were recognized. The increase in sulfate concentrations was
attributed to tailings oxidation and acid generation (Steffen Robertson & Kirsten 1991b).
Cyprus' original plan for reclamation of the tailings impoundment (submitted to the State in 1982)
provides for restoration of the Bruno Creek drainage through the impoundment in compliance with
State water quality standards. The plan indicates that Cyprus initially anticipated that water quality
standards could be met by diluting impoundment seepage with natural runoff. No water treatment
beyond sediment control was expected to be required (Steffen Robertson & Kirsten 1982). However,
the original reclamation plan did not consider the ARD issue.
According to Cyprus personnel, the ARD problem could extend well beyond the life of the mine and
perpetual care/treatment may be necessary. Therefore, Cyprus is currently evaluating remedial
alternatives (other than perpetual care) and is preparing to submit a revised tailings pond reclamation
plan (as a modification to their operating plan). Alternatives may include installing an additional
flotation unit to remove pyrite and/or in-place treatment of tailings with trisodium phosphate as a
buffer.
Preliminary flotation tests have been conducted to investigate the possibility of removing sulfides from
the tailings prior to disposal in the impoundment. Test results indicate that a high percentage of
pyrite may be recovered. Limited static testing performed on a whole tailings sample from which
18
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Site Visit Report: Cyprus Thompson Creek
pyrite was recovered indicated a NP/AP ratio in excess of 4:1 compared to an average value of
0.84:1 for all tailings analyses (Steffen Robertson & Kirsten 1991a).
Cyprus also has been testing the spray application of trisodium phosphate (2 percent solution) to
buffer tailings sands. The facility has been analyzing the buffered sands and collected leachate.
Based on preliminary test results, the trisodium phosphate has been successful in elevating pH levels
and reducing iron concentrations in leachate samples. However, because the tailings impoundment
unit has no discharge and water from the impoundment, seepage return pond, and pump back system
is returned to the mill, the TSP application will cause elevated phosphorus levels in the reclaim water.
Cyprus personnel indicated these levels may adversely affect flotation operations and that this issue is
being studied (Steffen Robertson & Kirsten 1991a).
According to Cyprus personnel, oxidation has only been found to occur in the top two to three feet of
tailings (despite the results of analyses of the 1990 borehole samples that showed oxidation at all
depths down to 150 feet, see Steffen Robertson & Kirsten, 1991a). Therefore, an additional
alternative under consideration is to encapsulate the tailings. Information on specific types of cover
materials was not provided. Additionally, Cyprus is investigating the potential use of wetlands
treatment.
Mine Water
Until early 1988, little or no mine water accumulated in the pit except seasonal runon. However,
ground water seepage to the pit began in 1988 when the pit reached the 7,300 foot elevation (a depth
of about 1,000 feet below the surface). As a result, a collection sump and pumpback system were
installed with a capacity to remove 1,200 gpm of mine water. According to Cyprus personnel, an
average of 200 gpm of mine water is pumped out of the pit to a booster station and then pumped to
the tailings impoundment. Because the mill was shutdown during 1991 spring runoff, mine water was
combined with underflow collected from the Pat Hughes dump and discharged through NPDES outfall
002 (after receiving approval from EPA). Under their water quality monitoring program, Cyprus
collects and analyzes samples of mine water from the collection sump. The results of mine water
analyses for 1989-1990 are presented in Table 2.
Other Materials and Wastes
Other wastes generated at the Cyprus Thompson Creek site include solid waste (i.e., trash), waste oil,
grease, and spent solvents). Each of these and their management practices are discussed below.
Other materials managed at the facility are also described.
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Site Visit Report: Cyprus Thompson Creek
Waste Oil/Grease/Fuel. Diesel fuel usage is approximately 220,000-230,000 gallons per month in the
mine trucks and 9,000 gallons per month in the mill. The primary fuel storage tank is a 400,000
gallon tank located north of the machine shop near the pit. There are also a 6,000 gallon tank for
auto transmission fluid and a 6,000 gallon tank for antifreeze storage located north of a gas shop, also
near the pit. Two 13,000 gallon underground tanks are used for gasoline storage (the locations of
these tanks were not obtained). Waste oil is collected in two aboveground 10,000 gallon tanks near
the shops. Vehicles generate 90 percent of the waste oil at the site. When vehicle waste oil was used
in blasting, all of the vehicle waste oil generated at Cyprus Thompson Creek was recycled on-site (the
amount was not determined). Forty percent of the vehicle waste oil was used in blasting and 60
percent was used in the facility's space heating furnaces. Because vehicle waste oil is no longer being
used in blasting pending MSHA approval, the management of waste oil not used in Cyprus' space
heating furnaces is unknown. The shop generates the remaining 10 percent of the facility's waste oil.
Shop waste oil is shipped off-site after analysis for chlorinated hydrocarbons. Grease is manifested
and also shipped off-site.
As noted in the facility's SPCC plan (see the following chapter), all of the tanks listed in the
preceding paragraph, except the two underground gasoline tanks, have secondary containment (i.e.,
liners surrounded by berms). None of these tanks have leak detection systems (Cyprus 1990). No
information was obtained on whether the two underground gasoline tanks have been leak tested.
Cyprus personnel visually inspect all tanks at the site at least monthly.
Solid waste. Solid waste generated at the site is disposed with waste rock materials in the Buckskin
dump. The quantity of solid waste generated and disposed was not obtained.
Solvents. In 1989, more than 12,000 pounds of naptha were generated and manifested for off-site
management. In 1989, 1,250 pounds of waste chlorinated cleaning solvents were generated and sent
to the State of Washington for disposal.
Capacitors. All PCB-contaminated capacitors were manifested and removed from the site in one
shipment (information on the removal date and quantity shipped was not obtained). According to
Cyprus, there is no remaining PCB-contaminated electrical equipment on the Thompson Creek
property.
Facility Runoff. All runoff from disturbed areas at the site (except for runoff from the mine, waste
dumps, and tailings impoundment) is collected in ditches, which drain to a sediment control pond
adjacent to Squaw Creek below the confluence with Bruno Creek. The site visit team observed a
significant algal bloom and aquatic plant life in the sediment pond. The discharge from the pond is
NPDES outfall 003.
20
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Table 2. General Surface Water Parameter Concentrations
for Pit Sump (PIT 1, PIT 2, and PIT 3)
Year
Parameter Range Concentrations
PH
Arsenic
Total jig/1
Barium
Total ftgfl
Cadmium
Total ng/1
Lead
Total pg/1
Mercury
Total jig/1
Selenium
Total ng/1
Silver
Total pg/l
Copper
Total /tg/1
Iron
Total Mg/1
Manganese
Total ftg/1
Zinc
Total jig/1
Aluminum
Total jtg/1
P1T1
1989
1990
6.8-7.0
6.3-6.7
10-36
NR
NR
NR
<5.0-
27.0
NR
50.0
NR
<0.50
NR
NR
NR
NR
NR
10
NR
2,500
NR
NR
NR
20-27
NR
NR
NR
PIT 2
1989
1990
PIT 3
1989
1990
6.5-7.4
3.6-6.5
<5.0-
77.0
<5.0-
19.0
6.5-7.3
5.9-7.0
<5.0-
129.0
167
NR
NR
NR
<100
<5.0-
68.0
5.0-14.0
<50.0-
150.0
60.0
< 5.0-5.0
-<5.0
<50.0-
80.0
<50.0
<0.50-
19.20'
<0.50
NR
NR
NR
NR
< 10-90
50-210
460-1,900
NR
NR
NR
< 5-302
337-
1,080
NR
NR
<0.50-
50.002
<0.50
NR
<20.0
NR
<5.00
10-30
<10
NR
700
NR
1,300
6-67
<5
NR
570
NR = Not Reported
(Source: Cyprus 1991a)
'Six of 39 samples showed detectable levels of mercury. Other detected levels ranged from 0.50 /ng/1 to 1.60 /xg/1. According to
Cyprus, laboratory contamination is suspected as the source for the anomalous mercury values
2Three of six samples showed detected levels of mercury. The other detected levels were 0.50 jwg/1 and 0.60 jtig/1.
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Site Visit Report: Cyprus Thompson Creek
REGULATORY REQUIREMENTS AND COMPLIANCE
Cyprus Thompson Creek operates under several permits and/or plans issued by the State of Idaho
Departments of Lands and Water Resources and Division of Environmental Quality, as well as
approvals from the U.S. Forest Service (USFS) and EPA Region X. In addition, the State of Idaho
has established an interagency task force that coordinates regulatory activities related to each major
mine site. The interagency task force for the Thompson Creek site meets quarterly and includes
representatives of the State Departments of Lands, Water Resources, and Fish and Game; the State
Division of Environmental Quality; USFS; and BLM. USFS is the lead agency for the Cyprus task
force. Each of Cyprus' major permits and/or plans is discussed in the following sections.
Plan of Operations
Background. Cyprus submitted their initial Plan of Operations to USFS for the Thompson Creek
mine on May 25, 1979. This plan, which was approved by USFS and has been modified throughout
the life of the mine, describes how the mine is to be operated and the specific activities to be
performed at mine closure. A part of the Plan of Operations is the reclamation plan for the site. In
addition to USFS approval, the reclamation plan and subsequent modifications are subject to review
by the Idaho Department of Lands under the Idaho Surface Mining Act.
Cyprus submits annual reports to the Idaho Department of Lands and USFS on reclamation and
tailings impoundment related activities. Cyprus also submits to the State, USFS, and EPA Region X
the results of all ground and surface water monitoring. Under the authority of the Surface Mining
Act, the Department of Lands coordinates with USFS to enforce the requirements of Cyprus' Plan of
Operations. Generally, the Department of Lands and USFS work with Cyprus to address any
problems that arise. If formal enforcement action is required, the Idaho Division of Environmental
Quality (DEQ) can issue a consent decree. The DEQ also reviews ground water and surface water
monitoring data to ensure compliance with State ground and surface water quality standards. BLM's
role at the site is limited to participation in the interagency task force.
The Forest Service inspects the site monthly. As noted above, staff from the State Departments of
Lands, Water Resources and Fish Game, and the Division of Environmental Quality participate in the
Thompson Creek interagency task force, which meets at the site quarterly.
Water Quality Monitoring. As part of their Plan of Operations, Cyprus is required to perform ground
and surface water monitoring in the Buckskin, Pat Hughes, Squaw, Bruno, and Thompson Creek
drainages, as well as the Salmon River drainage. The ground and surface water monitoring locations
22
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Site Visit Report: Cyprus Thompson Creek
(among which are the NPDES permitted outfalls described below) are identified in Table 3 and on the
maps presented in Figures 4 and 5. Parameters and monitoring frequencies vary between locations
(Cyprus 1991c). Information on the construction and depths of the ground-water monitoring wells
was not obtained.
A summary of the 1989 and 1990 monitoring data for each monitoring location is included in
Appendix A. Monitoring for pH and metals is required to ensure no degradation of surface and
ground water in the Salmon River basin (Cyprus 1991c).
Acid Rock Drainage Study. As noted in the previous chapter, Cyprus has been conducting a study to
investigate the potential for the waste dumps and the tailings impoundment to generate ARD. The
results of the ARD study of the waste rock and tailings were to be provided to USFS by March 1,
1992. Proposed revisions to the facility's reclamation plan were also to be submitted to USFS.
According to USFS personnel who participated in the site visit, the revisions to the Plan of Operations
will be subjected to the environmental review requirements of National Environmental Policy Act
(NEPA). This review may include preparation of a supplemental Environmental Impact Statement.
Reclamation. As required under their Plan of Operations, Cyprus submits an annual report describing
reclamation activities undertaken during the previous year and proposed activities for the following
year. The 1990 annual report, for example, described each specific project undertaken (e.g.,
stabilizing and fertilizing areas of the Buckskin and Pat Hughes dumps, seeding road cuts, and weed
control). Overall, Cyprus reported final reclamation of 30.8 acres in 1990 (compared to 6.5 acres
originally planned) (Cyprus 199Id).
Bonding. Because of the various agencies responsible for oversight of activities at the Thompson
Creek facility, coordinated bonding (including Memoranda of Understanding) has been required to
avoid duplication of requirements. Table 4 summarizes the agencies holding bonds, the bond values,
and the types of disturbances addressed. Overall, approximately $10,000,000 of bonds are held by
the USFS, BLM and the Idaho Departments of Lands and Water Resources for the Thompson Creek
Mine.
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Site Visit Report: Cyprus Thompson Creek
Table 3: Surface and Ground Water Monitoring Locations
Surface Water Monitoring Locations
SQ-2
SQ-2.5
SQ-3
SQ-4
TC-1
TC-2
TC-3
TC-4
001
002
003
PITS 1-3
SLMR1
SLMR2
SLMR3
TP
MD
LA
RA
PBS
DS-1
SP-1
RB-1
Squaw Creek below confluence with Bruno Creek and 25 feet above second bridge above gate.
Squaw Creek 250 feet below confluence with Bruno Creek (at boulder).
Squaw Creek above confluence with Bruno Creek and 100 feet below Redbird mine.
Bruno Creek at the U.S. Gauging Station (USGS) and above guard gate.
Thompson Creek 250 feet below confluence with Pat Hughes Creek and one mile above Transfer Pump
Sump.
Thompson Creek one-fourth mile above confluence with Pat Hughes Creek and below confluence with
Unnamed Creek.
Thompson Creek above confluence with Unnamed Creek and below confluence with Buckskin Creek.
Thompson Creek above confluence with Buckskin Creek and below confluence with Alder Creek.
Buckskin Creek sediment dam discharge point.
Pat Hughes Creek sediment dam discharge point.
Beaver Pond sediment control structure - storm water discharge point on Squaw Creek.
Locations in pit sump used for de watering.
Salmon River, 50 feet below steel ladder bridge (access road). South bank.
Salmon River, at parking flat directly above concrete bridge. South bank.
Salmon River, 50 feet above mouth of Thompson Creek.
Tailings pond (barge).
Main drain (lower center) of rock toe.
Left abutment of rock toe.
Right abutment of rock toe.
Pumpback system, inlet to sump on lower tailings road south of Seepage Return Dam.
First downstream spring 100 feet below pumpback system and 25 feet below monitoring well on Bruno
Creek (east bank).
Sediment pond at elevation 6,640 feet on Squaw Creek
Redbird Creek tributary to Squaw Creek one mile above Redbird Mine.
Ground Water Monitoring Locations
MW-1
BC-3
LA-2
RA-2
Monitoring well located approximately 100 feet below Seepage Return Dam.
Former production well on lower Bruno Creek at Pope John Boulevard.
Monitoring well located on left abutment above centerline of tailings impoundment.
Monitoring well located on right abutment (west edge) of tailings impoundment and one-half mile off of
upper mine (motivator) road.
.24
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Site Visit Report: Cyprus Thompson Creek
Table 4: Bond Amounts Required of Cyprus Thompson Creek
Through December 31, 1993
Agency Holding Bond
Dept. of Water Resources
Dept. of Lands
Total Bonds - $1 393 150
USFS
Total Bonding = $468,125
BLM
Total Bonding = $549,300
Disturbance Type
Tailings Deposition
Dumps
Roads & Utilities
Laydown & Shops
Remaining
Mine
Dumps
Tails - Deposition
Tails - Nondeposition
Borrow
Roads & Utilities
Laydown & Shops
Mine
Dumps
Tails - Deposition
Tails - Nondeposition
Borrow
Roads & Utilities
Laydown & Shops
Area
Acres
219.2
8
23
112
1,643
37.5
343
199.5
41
11.5
173
308.5
19.2
30.3
17
165
68.8
Base Rate
Cost/Acre
28,800
2,000
1,500
1,000
750
250
2,000
28,800
1,500
750
1,500
1,000
250
2,000
28,800
1,500
750
1,500
1,000
Portion Covered by Other Bonds
Lands
750
1,800
750
750
750
750
750
750
750
750
750
750
750
750
750
750
Water
28,050
28,050
USFS
BLM
Adj. Rate
Cost/Acre
28,050
~
(500)
1,250
,
750
750
250
(500)
1,250
750
750
250
Total
Total ($)
7,517,455
$14,400
34,500
112,000
1,232,250
$428,750
30,750
8,625
385,625
22,725
123,750
17,200
9,928,030
25
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Site Visit Report: Cyprus Thompson Creek
26
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Bruno Creek
LA>2
Embankment
Figure 5. Monitoring Locations
In Tailings Impoundment Area.
Surface Water Monitoring Location
Ground Water Monitoring Location
(Source: Cyprus 199ta)
Note: TNs map Is not drawn to scale.
' x MD Seepage Return
f ^^ "
Dam
1
I
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Site Visit Report: Cyprus Thompson Creek
Old Tungsten Mill Tailings Remediation. As indicated previously, an abandoned mill associated with
an old tungsten mine is located beside Thompson Creek 10 miles downstream of the mine site (not on
Cyprus' property). The tailings from the mill were disposed in and around the creek drainage.
These tailings have been shown to have acid generation potential (pH approximately 2.9 s.u.) and
high metals concentrations which could affect Thompson Creek. Although the abandoned mill tailings
are not on Cyprus' property, their potential impact on the Creek affects Cyprus' nearby operations.
Therefore, it is to Cyprus' benefit to assist hi remediation of the site. In a joint effort, Cyprus has
been working with the USFS to remediate problems associated with the tailings. Tailings are being
removed from the Creek and placed on other tailings away from the drainage. They are then covered
from top to bottom with layers of lime, topsoil, sewage sludge, and additional topsoil. Cyprus is
providing the equipment and operators, while USFS is providing funding, expertise, and additional
manpower.
NPDES Permit
The State of Idaho has not been delegated NPDES permitting authority under the Clean Water Act.
Therefore, the five-year NPDES permit for the Cyprus Thompson Creek site was issued by EPA
Region X on August 1, 1988. The permit specifically addresses the discharges from NPDES outfalls
001 (the discharge from the Buckskin dump) and outfall 002 (the discharge from the Pat Hughes
dump). For these outfalls, the permit establishes limits and monitoring requirements for: pH
(monitored weekly), total suspended solids (weekly), arsenic (monthly), cadmium (monthly), lead
(monthly), mercury (monthly), copper, (monthly) and zinc (monthly). Permit limits are based on
ensuring compliance with the applicable State water quality standards. However, the permit provides
alternative limitations for the metals (except arsenic) to allow for elevated levels of pollutants in
background water quality (USEPA 1988).
As noted previously, Cyprus collects runoff from all areas (other than the pit, waste dumps, and
tailings impoundment) in unlined channels that convey runoff to a sediment pond located adjacent to
Squaw Creek downstream of the confluence with Bruno Creek. This pond discharges to Squaw Creek
at NPDES outfall 003. Cyprus is required to monitor Squaw Creek upstream and downstream of this
outfall for turbidity. Weekly monitoring is required between February 1 and June 30 and monthly
during other months. The permit only requires turbidity monitoring, no limits are provided (USEPA
1988).
The NPDES permit also requires Cyprus to continue to implement the comprehensive water quality
monitoring program described under the operating plan above. Cyprus submits quarterly reports on
water quality monitoring to both EPA Region X and DEQ. EPA Region X's Water Quality Branch
conducts a compliance inspection at the facility once per year.
28
-------
Site Visit Report: Cyprus Thompson Creek
Cyprus personnel indicated that the water quality in the receiving waters was generally "very good,"
including pH levels (see Appendix A). To further determine whether mining activities have impacted
surface waters, Cyprus conducted an aquatic biological survey of Thompson and Squaw Creeks. The
results of this 1988 study indicated that mining was having no discernable effect on aquatic life in
Thompson Creek. The invertebrate populations in Squaw Creek were shown to have experienced
changes in species composition and relative density. However, the cause of these changes was
unknown and continued monitoring was recommended (Chadwick & Associates 1989). Annual
aquatic life monitoring is now required under Cyprus' water quality monitoring program (no
additional data was obtained). During the site visit, Cyprus personnel noted that in 1986, one of the
waste dump ponds stratified, confining higher temperature (lower oxygen) water at depths in the
pond. Because of this effect, the decreasing level of oxygen caused fishkills.
Air Permit
The State of Idaho has issued an air emissions permit for the Thompson Creek site that addresses the
following sources:
Baghouses located at the crusher, at the turning point of the conveyor, at the lime bin, at the
product package area, and at the HPM plant,
Discharges from the two boilers in the mill,
Portable crusher used to generate gravel for roads; water is sprayed at the base of this crusher to
control paniculate emissions,
Technical grade concentrate holoflyte dryer/rotary kiln stack,
HPM plant holoflyte dryer/rotary kiln stack.
Dust collected from the baghouses is recycled to the mill. All of the above sources are required to
meet 20 percent opacity limits and the paniculate size limit for each source is either 0.02 or 0.5
grains/dry cubic foot. In addition, the fuel feed to the mill boilers must be less than one percent
sulfur. The State conducts air permit compliance inspections once per year. Magnesium chloride is
used for dust suppression on haul roads.
Dam Safety Permit
As required under Idaho State law, Cyprus Thompson Creek has a dam safety permit issued by the
Department of Waste Resources for the main tailings embankment and the SRD. This permit was not
reviewed by the site visit team.
29
-------
Site Visit Report: Cyprus Thompson Creek
Other Regulatory Requirements
In accordance with 40 CFR Part 112 of the Clean Water Act, Cyprus has implemented a spill
prevention control and countermeasure (SPCC) plan for the Thompson Creek mine site, primarily
because of the project's location adjacent to and near a number of tributaries to the Salmon River.
The SPCC plan is designed to help prevent spills and to minimize the risk of injury to human health
and the environment in the event that a spill should occur. Cyprus's SPCC plan specifically: (1)
provides the locations of all aboveground storage tanks at the site, (2) describes their contents and
volumes, and (3) identifies spill prevention and control measures. As noted previously, all of the
aboveground tanks at the site have secondary containment and are visually inspected monthly.
According to Cyprus personnel, the two underground gasoline storage tanks at the site are in full
compliance with Underground Storage Tank program requirements.
30
-------
Site Visit Report: Cyprus Thompson Creek
REFERENCES
Chadwick & Associates, 1989. Draft Aquatic Biological Survey of Thompson Creek and Squaw
Creek. Prepared for Cyprus Minerals Corporation. March 1989.
Cyprus Minerals Corporation, 1990. Spill Prevention Control and Countermeasure Plan, December
12, 1990.
Cyprus Minerals Corporation, 1991a. Water Quality Monitoring Program Results for 1989-1990.
Cyprus Minerals Corporation, 1991b. Cyprus Thompson Creek Annual Tailings Report, 1990.
Submitted to the Idaho Department of Water Resources. March 25, 1991.
Cyprus Minerals Corporation, 1991c. Cyprus Thompson Creek: 1991 Water Quality Monitoring
Program.
Cyprus Minerals Corporation, 1991d. Cyprus Thompson Creek Molybdenum Mine, Reclamation and
Planned Renewal Activities, 1990 Annual Report. Prepared for the Idaho Department of Lands.
March 27, 1991.
Piteau Associates, 1989. Geotechnical Review of Buckskin Creek Waste Dump. Prepared for Cyprus
Minerals Corporation. January 25, 1989.
State of Idaho. Water Quality Standards. Revised as of 1989.
Steffen Robertson & Kirsten, 1982. Conceptual Reclamation Plan and Cost Estimate.Thompson
Creek Project, Tailings Impoundment. Prepared for Cyprus Minerals Corporation. December
1982.
Steffen Robertson & Kirsten, 199 la. Memo to Bert Doughty of Cyprus Thompson Creek on the Status
of the Thompson Creek ARD Investigation. August 19, 1991.
Steffen Robertson & Kirsten, 1991b. Memo to Bert Doughty of Cyprus Thompson Creek on the ARD
Investigation of Cyprus Thompson Creek's Tailings Impoundment. April 9, 1991.
U.S. Environmental Protection Agency, Region X, 1988. NPDES Permit No. ID0025402. Issued on
June 30, 1988.
31
-------
Site Visit Report: Cyprus Thompson Creek
U.S. Forest Service, 1980. Final Environmental Impact Statement, Thompson Creek Molybdenum
Project, Challis, Idaho.
32
-------
Site Visit Report: Cyprus Thompson Creek
APPENDIX A
WATER QUALITY MONITORING DATA
-------
Monitoring Results for Surface Water Stations in Squaw Creek (SQ-2, SQ-2.5, SQ-3, and SQ-4)
Year
Concentration Ranges
pH
As
Total
/*g/l
Ba
Total
Pg/1
Cd
Total
pg/1
Pb
Total
Mg/i
Hg
Total
wn
Se
Total
Mg/l
Ag
Total
Pg/1
Cu
Total
pg/1
Fe
Total
Mg/1
SO-2
1989
1990
6.9-8.5
6:1-8.0
<5.0
<5.0
<100
<100
<5.0
<5.0
<50.0
<50.0
<0.50
<0.50
<2.0
<5.0
<5.00
<5.00
SO-2.5
1989
1990
6.9-8.1
7.8
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
< 10-10
<10
<10-
120
90-190
Mil
Total
pg/i
Zn
Total
/*g/l
Al
Total
Mg/1
< 10-10
<50
NR
NR
NR
NR
NR
NR
<5-15
<5-13
<100
<100
NR
NR
NR
NR
SO-3
1989
1990
6.8-8.3
6.4-8.1
<5.0
<5.0
<100
<100
12.0
<5.0
<50.0
<50.0
SO-4
1989
1990
6.6-8.6
7.5-8.3
<5.0
<5.0
<100
200
<5.0
<5.0
<50.0
140.0
<0.50
<0.50
<2.0
<5.0
<5.00
<5.00
<10
20
<0.50
0.50
<2.0
<5.0
<5.00
<5.00
10
NR
50-140
100-150
< 10-10
< 50-50
20
<5
<100
<100
< 10-80
50-110
<10
<50
13
12-15
100
270
NR = Nonreporting
A-l
-------
Monitoring Results for Surface Water Stations: Downstream Spring (DS-1), Left Abutment (LA), Pumpback System Inflow (PBS),
Right Abutment (RA), Redbird Creek (RB-1), and Sediment Pond (SP-1)
Year
DS-1
1989
1990
Concentration Ranges
PH
As
Total
Mg/1
Ba
Total
Mgfl
Cd
Total
Mg/I
Pb
Total
Pg/1
Hg
Total
/*g/>
Se
Total
/*g/I
Ag
Total
Mg/I
Cu
Total
Mg/1
Fe
Total
A»8/»
Mn
Total
'«/!
Zn
Total
Mg/1
Al
Total
Mg/1
6.4-8.0
5.3-7.9
<5
<5
<100
<100
<5.0
<5.0
<5
60
<.5
<.5
<2
<5
<50
<5
<10
NR
20-290
60-170
LA
1989
1990
6.4-7.1
6.7-6.8
<5-6
<5
170-700
< 100-150
5-9
<5-10
< 50-1 10
60-70
<. 5-2.4
<.5
PBS
1989
1990
6.5-7.0
6.2-7.2
<5-6
<5-19
RA
1989
1990
RB-1
1989
1990
SP-1
4.2-8.2
6.9-7.8
<5
<5
100-1,900
< 100-130
5-28
6-11
<100-
1,100
<100
<5-15
<5-10
60-90
50-110
<1
<.5-.6
<2
<5
<5-10
6-8
< 10-30
20-30
200-820
150-210
<2
<5
<5-8
7-11
< 50-80
< 50-1 10
<1
<.5-.5
<2-4
<5
<5-6
<5-10
< 10-10
< 10-10
40-180
50-130
<10-10
<50
<5-12
<5-ll
200
400
260-770
140-310
11-65
14-71
< 100-490
< 100-1 10
< 10-20
<50
12-64
9-49
<100
< 100-300
< 10-50
< 10-10
550-
58,000
190-
1,100
20-
10,700
<50-
8,000
21-360
21-50
300-
15,600
< 100-550
8.5
6.8-8.1
<5
<5
<100
<100
<5
<5
<50.0
<50.0
<.5
< 5
<2
<5
<5.00
<5.00
<10
10
80
50
<10
<50
9
<5
200
430
A-2
-------
1989
1990
7.1-8.8
6.2-8.6
<5
<5
<100
<100
<5
<5
<50.0
70.0
<.5
<.5
<2
<5
<5.00
<5.00
<10
NR
10-80
50-70
<10
<50
44
34-37
<100
250
NR = Nonreportmg
A-3
-------
Monitoring Results for Surface Water Stations
Tailings Pond (TP) and Main Drain (MD)
Year
IP
1989
1990
MD
1989
1990
pH
6.4-8.7
5.7-7.1
5.8-7.1
5.2-7.7
As
Total
J*/l
<5.0
<5.0
<5.0
<5.0
Ba
Total
Pg/1
200-400
<100-
120
200-800
<100-
460
Concentration Ranges
Cd
Total
rtg/1
<5.0-
12.0
<5.0-
14.0
Pb
Total
«/l
Hg
Total
08/1
Se
Total
Mg/1
90.0-160
<50.0-
70.0
<0.50-
1.00
<0.50-
0.50
4.0-7.0
4.0-9.0
Ag
Total
Mg/1
Cu
Total
Mg/1
Fe
Total
Mg/1
<:5.o-
9.0
<5.0-
6.0
5.0-8.0
5.0-10.0
70.0-
100.0
<50.0-
130.0
<0.50-
1.00
<0.50-
0.80
<2.0
<2.0-
<5.0
6.00-
9.00
<5.00-
10.00
< 10-60
10-20
240-
2,000
170-400
Mn
Total
/*g/l
Zinc
Total
Mg/1
Al
Total
Pg/1
410-
3,400
270-950
11-34
<5-112
480-1,220
<100-
550
10-20
10-20
3,500-
5,000
2,700-
9,400
1,200-
1,600
910-
9,600
9-124
26-42
<100-
880
<100-
650
NR = Nonreporting
A-4
-------
Monitoring Results for Surface Water Station in
Salmon River (SLMR 1, SLMR 2, and SLMR 3)
Year
SLMR1
1989
1990
Concentration Ranges
pH
As
Total
pg/1
Ba
Total
0g/l
Cd
Total
ftg/1
Pb
Total
Jig/1
Hg
Total
/*g/i
Se
Total
Atg/1
Ag
Total
Pg/t
6.5-8.2
7.3
SLMR 2
1989
1990
6.5-8.1
7.0
<5.0
<5.0
<100
110
<5.0
<5.0
<50.0
<50.0
<0.50-
0.70
0.60
<2.0
<5.0
<5.00
<5.00
Cii
Total
/tg/l
Fe
Total
jtg/1
Mn
Total
Mf/1
Zn
Total
Pg/1
Al
Total
f*/l
< 10-10
20
<5.0
<50
<100
110
<5.0
<5.0
<50.0
<50.0
<0.50
<0.50
<2.0
<5.0
<5.00
<5.00
<10
<10
40-470
<50
< 10-20
<50
11-22
<5
<100-
510
100
20-520
50
< 10-20
<50
10-11
<5
<100-
550
<100
SLMR 3
1989
1990
6.8-7.6
6.7
<5.0
<5.0
<100
<100
<5.0
<5.0
<50.0
<50.0
<0.50
<0.50
<2.0
<5.0
<5.00
<5.00
<10
<10
90-350
2,000
10-20
<50
5-14
<5
<100-.
410
210
NR = Nonreporting
A-5
-------
Monitoring Results for NPDES Permitted Discharges to Buckskin Creek (001),
Pat Hughes Creek (002), and Bruno Creek (003)
Year
001
1989
1990
002
1989
1990
003
1989
1990
Concentration Ranges
pH
As
Total
fi£tl
Ba
Total
Pg/1
Cd
Total
*»g/I
Pb
Total
«/l
Hg
Total
Mg/l
Se
Total
/ig/1
Ag
Total
/tg/1
Cu
Total
Mgft
7.0-9.2
7.1-8.9
<5.0
<5.0
NR
NR
4.0-
<5.0
<5.0
<50.0
50.0
<0.20-
24.00
0.40-
0.80
NR
NR
NR
NR
<10-
<20
<10
Fe
Total
Mg/1
Mn
Total
ftg/1
Zn
Total
Mg/1
Al
Total
Mg/1
60
NR
NR
NR
6.6-8.9
6.4-8.9
<5.0
<5.0
NR
<100
<5.0-
9.0
<5.0-
8.0
<50.0-
44.0003
<50.0-
70.0
6.6-8.3
6.3-8.1
<5.0
<5.0
<100
<100
<5.0
<5.0
<50.0
60.0
<0.20-
10.90
<0.20-
5.00
NR
<5.0
NR
<5.00
< 10-20
< 10-20
50-80
70
<0.50
2.00
<2.0
<5.0
5.00
<5.00
10
<10
50
110
NR
<50
4-27
8-19
< 5-172
<5-65
NR
NR
NR
300
30
70
20
10
<100
130
NR = Nonreporting
3This value may be inaccurate because the results of analysis of all other samples collected from outfall 002 showed lead levels of 90 /ig/1
or less. No other information was available.
A-6
-------
Monitoring Results for Surface Water Stations in Thompson Creek (TC-1, TC-2, TC-3, and TC-4)
Year
TC-1
1989
1990
TC-2
1989
1990
TC-3
1989
1990
TC-4
1989
1990
Concentration Ranges
PH
As
Total
Mg/i
Ba
Total
J*g/l
Cd
Total
«E/1
Pb
Total
Mg/l
Hg
Total
/tg/1
Se
Total
Mg/1
Ag
Total
pgfl
Cu
Total
Pg/1
Fe
Total
jig/I
Mn
Total
J*/l
Zn
Total
/*g/l
Al
Total
/tg/1
6.6-8.1
6.2-7.8
<5.0-
6.0
<5.0
<100
<100
6.7-7.7
6.3-7.9
<5-ll
NR
<100
NR
<5.0-
27.0
<5.0
<50.0
<50.0
<0.50-
2.60
<0.50
<2.0
<5.0
<5.00
<5.00
<5.0
NR
<50.0
<50.0
<0.50
<0.50
<2.0
<5.0
<5.00
<5.00
< 10-20
<10
20-30
100
10
<50
<5-21
<5
<100
380
<10-
<20
<10
130
<50
10
<50
11-25
NR
<100
NR
6.8-7.8
6.1-8.0
5.9-7.9
6.2-7.9
<5.0
NR
<100
NR
<5.0
NR
<50.0
<50.0
<0.50
<0.50
<2.0
<5.0
<5.00
46.00
<10-
<20
<10
40
230
<10
<50
6-18
NR
<100
NR
<5.0
<5.0
<100
<100
<5.0-
9.0
<5.0-
6.0
<50.0
<50.0-
70.0
<0.50-
6.80
<0.20-
2.90
<2.0
<5.0
46.00
<5.00
< 10-20
< 10-20
20-400
140
<10
<50
< 5-166
<5-18
<100
190
NR = Nonreporting
A-7
-------
General Surface Water Parameter Concentrations for Pit Sump (PIT 1, PIT 2, and PIT 3)
Year
PIT1
1989
1990
PIT 2
1989
1990
PITS
1989
1990
Parameter Range Concentrations
pHFLD
*
6.8-7.0
6.3-6.7
Arsenic
Total
Wfl
10-36
NR
Barium
Total
J*g/l
NR
NR
Cadmiu
m
Total
«/»
<5.0-
27.0
NR
Lead
Total
«/i
50.0
NR
Mercury
Total
Mg/»
<0.50
NR
Seleniu
m
Total
Pg/1
NR
NR
Silver
Total
«/l
NR
NR
Copper
Total
Mg/l
10
NR
/
Iron
total
Mg/l
2,500
NR
Mangns
Total
/»g/i
NR
NR
Zinc
Total
pg/1
20-27
NR
Aluminu
m
Total
/^g/1
NR
NR
6.5-7.4
3,6-6.5
<5.0-
77.0
<5.0-
19.0
NR
NR
<5.0-
68.0
5.0-14.0
<50.0-
150.0
60.0
<0.50-
19.20
<0.50
NR
NR
NR
NR
< 10-90
50-210
460-
1,900
NR
NR
NR
< 5-302
337-
1,080
NR
NR
6.5-7.3
5.9-7.0
<5.0-
129.0
167
NR
<100
<5.0-
5.0
<5.0
<50.0-
80.0
<50,0
<0.50-
50.00
<0.50
NR
<20.0
NR
<5.00
10-30
<10
NR
700
NR
1,300
6-67
<5
NR
570
NR = Nonreporting
A-8
-------
Cyprus Thompson Creek Mining Company
Concentrator Daily Tailings Composit Assays
Report Date: 28/Jan/91
Sample
Rougher Tails
Combined Tails
Scavenger Tails
Rougher Concentrate
1st Cleaner Concentrate
2nd Cleaner Tails
Molybdenum
Percent
0.009
0.009
0.073
8.11
43.40
34.10
Copper
Percent
0.002
0.004
0.150
0.130
0.620
1.300
Lead
Percent
0.002
0.003
0.051
0.060
0.180
0.240
A-9
-------
Site Visit Report: Cyprus Thompson Creek
Surface Water Monitoring Locations:
SQ-2:
Squaw Creek below the confluence with Bruno Creek and 25 feet above the second bridge above
the gate.
SQ-2.5:
Squaw Creek 250 feet below the confluence with Bruno Creek (at boulder).
SQ-3:
Squaw Creek above the confluence with Bruno Creek and 100 feet below Redbird mine.
SQ-4:
Bruno Creek at the U.S. Gauging Station (USGS) and above the guard gate.
TC-1:
Thompson Creek 250 feet below the confluence with Pat Hughes Creek and one mile above the
Transfer Pump Sump.
TC-2:
Thompson Creek one-fourth mile above the confluence with Pat Hughes Creek and below the
confluence with Unnamed Creek.
TC-3:
Thompson Creek above the confluence with Unnamed Creek and below the confluence with
Buckskin Creek.
TC-4:
Thompson Creek above the confluence with Buckskin Creek and below the confluence with Alder
Creek.
001:
Buckskin Creek sediment dam discharge point.
002:
Pat Hughes Creek sediment dam discharge point.
003:
Beaver Pond sediment control structure - storm water discharge point on Bruno Creek.
PITS 1-3: Locations in pit sump used for dewatering.
SLMR1:Salmon River, 50 feet below steel ladder bridge (access road). South bank.
SLMR2:Salmon River, at parking flat directly above concrete bridge. South bank.
SLMR3: Salmon River, 50 feet above mouth of Thompson Creek.
TP:
Tailings pond (barge).
MD:
Main drain (lower center) of the rock toe.
LA:
Left abutment of the rock toe.
RA:
Right abutment of the rock toe.
A-10
-------
Site Visit Report: Cyprus Thompson Creek
PBS:
Pumpback system, inlet to sump on lower tailings road south of the Seepage Return Dam.
DS-1:
First downstream spring 100 feet below pumpback system and 25 feet below the monitoring well
on Bruno Creek (east bank).
SP-1:
Sediment pond at elevation 6,640 feet on Bruno Creek, one-half mile below pumpback system.
RB-1:
Redbird Creek tributary to Squaw Creek one mile above Redbird Mine.
Ground Water Monitoring Locations:
MW-1:
Monitoring well located approximately 100 feet below the Seepage Return Dam.
BC-3:
Former production well on lower Bruno Creek at Pope John Boulevard.
LA-2:
Monitoring well located on the left abutment above the centerline of the tailings impoundment.
RA-2:
Monitoring well located on the right abutment (west edge) of the tailings impoundment and one-
half mile off of the upper mine (motivator) road.
A-ll
-------
Ground Water Monitoring Results for Bruno Creek Artesian Well (BC-3), Tailings Left Abutment Well (LA-2),
SRD Monitoring Well (MW-1), and Tailings Right Abutment Well (RA-2)
Year
BC-3
1989
1990
LA-2
1989
1990
MW-1
1989
1990
RA-2
1989
1990
Concentration Ranges
pH
As
Total
Mg/l
Ba
Total
/*g/l
Cd
Total
/*g/l
Pb
Total
Pg/1
Hg
Total
Mg/1
Se
Total
Mg/1
Ag
Total
Mg/l
Cu
Total
Mg/1
Fe
Total
Mg/1
Mn
Total
A*g/l
Zn
Total
Pgfl
Al
Total
Mg/1
6.9-7.9
6.6-7.6
<5.0
<5.0
<100
<100
<5.0
<5.0
<50.0
<50.0
<0.50
<0.50
6.7-7.2
NR
<5.0
NR
<100
NR
<5.0
NR
<50.0
NR
<0.50
NR
<2.0
<5.0
<5.00
<5.00
<2.0
NR
<5.00
NR
<10
NR
6,500-
7,400
4,200-
7,200
140-170
100-130
80
<5-34
<100
<100
< 10-10
NR
6.6-7.7
6.7-8.0
<5.0-
23.0
<5.0
300
<100
<5.0-
32.0
7.0
<50.0-
190.0
60.0
<0.50-
3.30
<0.50
<2.0
<5.0
<5.00
<5.00
<10-
120
NR
350-530
NR
60-100
NR
8-18
NR
150-300
NR
2,100-
14,000
1,800-
2,000
100-890
70-90
20-
11,800
68-137
44,000
420
6.4-6.8
5.8
8.0-17.0
<5.0
<100
130
<5.0
<5.Q
<50.0
<50.0
<0.50
<0.50
<2.0
<5.0
<5.00
<5.00
<10-
<20
<10
1,400-
5,300
210
150-440
<50
<5-36
17
600-
1,400
600
NR = Nonreporting
A-12
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Site Visit Report: Cyprus Thompson Creek
APPENDIX B
CYPRUS MINERALS COMPANY COMMENTS
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Site Visit Report: Cyprus Thompson Creek
Cyprus Comments on EPA's Thompson Creek Mine Report
June 5. 1992
The following comments on EPA's MINE SITE VISIT: CYPRUS THOMPSON CREEK tdraft>
dated April 1992 are presented in accordance with the reports organization.
INTRODUCTION
Background
Page 1, at the bottom of the page, the correct titles and company names are:
Cyprus Minerals Company
Les Darting, Director, Environmental Affairs (303)643-5325
Cyprus Coaoer Company
Jamie Sturgess, Manager, Environmental Affairs, (303) 643-5782'
Page 2, at the top of the page, the correct titles and company names are:
Cvorus Thompson Creek (208) 838-2200
Bert Doughty, Supervisor, Environmental Affairs
Don HiUeary, Chief Engineer
Jim Kopp, Operations Supervisor
Marvin Harmer, Chief Metallurgist
Turk Territt, Mine Superintendent
General Facility Description
^»
Page 2, first paragraph, last sentence should read:
The active facility is located on nearly 1,935 acres of mixed ownership including:
private lands (521 acres). Bureau of Land Management administered federal land
(781 acres), and USFS administered federal land (633 acres of the Chat/is National
Forest).
Page 2, first paragraph, the following sentence should be added to the end of the
paragraph (above):
Cyprus controls a mineral claim block of about 16,000 acres around the Thompson
Creek Mine.
B-l
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Site Visit Report: Cyprus Thompson Creek
V.
Cyprus Minerals Co. Comments - Thompson Creek Report
June 5, 1992
page 2
Page 2, second paragraph, first sentence should read:
The mine is located in Caster County, approximately 35 mites southwest of Challis,
the county seat of Ouster County.
Page 4, second full paragraph, first sentence should read:
The Cyprus Thompson Creek Mine site currently consists of (1) an open pit mine
and two associated waste rock dumps, (2) a primary crusher, (3) a mill that
includes grinding, concentration by flotation, and (4) a tailings impoundment.
Environmental Setting - .'
. .'Page 5, Figure 2.: The figure shows a non-existing "unnamed creek" flowing from the pit
,A.. SL to the Salmon River between Pat Hughes Creek and Buckskin Creek. It also shows a
* x settling pond on this unnamed and non-existing drainage. This Figure should be corrected.
V ^ Pa9e 7>tnird paragraph: Delete the last sentence as it duplicates the penultimate /
v^: l v sentence.
7 7C
£ Page 8, first incomplete paragraph, last sentence should read:
C x o* Other than the on-slte wells, the nearest drinking water well is at the Red Bird Mine
.N) ,* three miles from the mine site.
>tf x Facility Operations
<* S
; ' Page 9. first paragraph, fourth, fifth and sixth sentences should read:
*V
'V In 1986, the mill was shut down for one month. The mill was also inactive from
October 1987 to March 1988, when only minor stripping operations (i.e., removal
of overburden and waste rock) were underway. Again, from May 1991 to
November 1991 the mill was not operated but waste rock and-overburden stripping
operations in the mine continued to access additional ore.
Mining Operations
Page 9, second paragraph, second to the last sentence should read:
The pit currently extends down to the 7,050 foot level, with plans to expand down
to an elevation of 6,400 feet (i.e., to a depth of 2,000 feet).
Page 9, third paragraph, second to the seventh sentence should read:
The ore is accessed by drilling and blasting along 50 foot benches. Drilling is
accomplished using Marion electric drills and a typical blast pattern consists of
B-2
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Site Visit Report: Cyprus Thompson Creek
Cyprus Minerals Co. Comments - Thompson Creek Report
JuneS, 1992
page 3
between 30-40 holes. ANFO, a blend of ammonium nitrate and diesel fuel, is used
as the blasting agent (10,000 tons of ANFO is used annually). (Waste oil has been
substituted for diesel fuel in the ANFO mixture, however, it is currently not being
used pending MSHA approval.! On average, one blast occurs every other day.
After fragmentation, ore and waste rock are excavated using P & H electric
shovels. Cyprus currently has two 28 cubic yard shovels, one 17 cubic yard
shovel, and two 15 cubic yard shovels.
Page 10, continuation of previous page paragraph, first sentence should read:
7770 stripping ratio is approximately 2:1 (waste rock:ore). '
Milling Operations
Page 10, second paragraph, third and fourth sentence should be replaced with:
I
The gyratory crusher is equipped with a bag house for controlling particular
emissions.
The water sprays are on the portable crusher which is intermittently used for gravel
production.
Page 10, third paragraph, second sentence should read:
The conveyor belt is 2,350 feet long and 60 inches wide.
Page 10. third paragraph, fourth sentence should read:
However, Cyprus personnel indicated that 75,000 tons of ore comprise the "active")
portion of the pile.
Page 10, third paragraph, sixth sentence to the end of the paragraph should read:
Ore fs removed from the surge pile by eight feeders underneath the pile. The ore is
then transported to two parallel grinding circuits. In each circuit, the ore initially
enters a 32 foot diameter semi-autogenous grinding (SAG) mitt. The outputs from
the SAG mills is passed over 0.75 inch screens and flows Into cyclone separators.
The overflow from the cyclones goes directly to flotation, while the underflows go
to 16.5 foot by 26 foot ball mills for further grinding prior to flotation. Grinding is a
wet process and burned lime is added for pH control. In 1990, Cyprus used an
average of 0.132 pounds of lime per ton of ore. The grinding circuit product is 35
percent so/ids.
Page 10, last paragraph, third and fourth sentences should read:
Fuel oil is used as the collector, alcohol is used as the frother, while a Notes
B-3
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Site Visit Report: Cyprus Thompson Creek
Cyprus Minerals Co. Comments - Thompson Creek Report
JuneS, 1992
page 4
reagent (P^, & NaOH) is added in the cleaner stages to depress copper and lead. \
In 1990, Cyprus used an average of 0.117 pounds of fuel oil, .025 pounds of *
alcohol, and 0.011 pounds of Nokes reagent per ton of ore.
Page 10, last paragraph, last sentence should read:
The effluent from the small ball mill is then subjected to ten additional stages of i
flotation, called "cleaner" stages, to progressively upgrade the concentrate.
Page 1 2, first paragraph, third sentence should read:
. The larger particles (those that don't pass through the screen} are sent to Cyprus' '
High Performance Molybdenum (HPM) plant.
Page 1 2, first paragraph, after the fourth sentence the following should be added:
The higher grade (screen oversize) reports to either the high grade flotation plant or \
the drying and packaging plant, depending upon market requirements. In the high
grade plant the mofy is reground and subjected to either one or two stages of
column flotation, again dependent upon market conditions.
Page 1 2, first paragraph, the sentence after the addition directly above should read:
The concentrate, which is 15-18 percent water, is then passed through a filter \
press. The filtrate....
Page 1 2, second paragraph, beginning with the second sentence to the end of the
paragraph should read:
When dry, the concentrate is a very fine powder, about 54 to 59 percent -.
molybdenum disulfide with less than 9.0 percent water and 1.O percent fuel oih
The concentrate is packaged in 4,OOO pound bags and sent by truck to deep water
ports or the Cyprus Sierrita facility, in Arizona for roasting. ~ ..
Page 1 2, last paragraph, first and second sentences should read:
The "higher grade" larger crystals from the final cleaner stages go to a filter.
are then separately filtered and dried in the holoflyte dryer/rotary kiln.
Page 1 2, last paragraph, a sentence should be added at the end that reads:
This product is <* 59 percent Mo with less than one percent water and 0. 1 percent
fuel oil.
B-4
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Site Visit Report: Cyprus Thompson Creek
Cyprus Minerals Co. Comments - Thompson Creek Report
JuneS. 1992
page 5
Waste Management Waste Rock
Page 13, second paragraph, first sentence should read:
As noted in the previous chapter, approximately 16.2 million cubic yards of waste j
rock were generated in 1990. with the stripping ratio typically about 2:1
(waste:ore),
Page 1 3. third paragraph, fourth and fifth sentences should read:
The dump is currently Jtdff feet high and is planned to eventually extend from ant
elevation of 8, 100 feet to 7,600 feet. A 300-foot-wide bencwwhich enhancer
stability, is currently situated at the 7,600 elevation.
Page 14, last paragraph, delete the last sentence and replace it with the following:
Seventy-six volcanic samples were run for acid base accounting with NP/AP ratios
of over 31:1.
Page 1 5, first paragraph, penultimate sentence should read:
A NALCO coagulant is added to the sediment ponds during the spring to help]
control total suspended solids levels in the pond discharges.
Tailing*
Page 15, second paragraph, the paragraph section above the table should j^ad:
When the mill is operating at full production, tailings are generated at a rate of
approximately 7.5 million cubic yards per year. On a 10/4 mill operating schedule,
about 5.5 mi/lion cubic yards of tailings are produced each year. Cyprus
continuously monitors the composition of concentrates and tailings generated by
each flotation Stage to assess mill performance. Samples are collected every 15
minutes and composited for analysis every 24 hours. The results of one recent
analysis of a 24-hour composite are presented in Table 1. As indicated in the
previous section, only the rougher and scavenger tails are sent to the tailing
impoundment.
Page 16, first paragraph, first sentence should read:
Tailings flow from the mill in a 30-inch diameter high density polyethylene (HOPE)
pipeline that extends 7,000 feet north-northeast to the tailings impoundment .
located in the Bruno Creek drainage. V
<
B-5
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Site Visit Report: Cyprus Thompson Creek
Cyprus Minerals Co. Comments - Thompson Creek Report
JuneS, 1992
page 6
Page 16, first paragraph, last sentence should read:
The pipeline is placed in a ditch along its entire length to provide secondary '
containment.
Page 16, third paragraph: Strike the tenth sentence: "Cyprus personnel indicated that
approximately 120 gpm of tailings water is lost to infiltration." We are unsure of the
meaning of this sentence. Infiltration to what? Water that seeps through the tailing
impoundment is captured in the seepage collection ponds below the impoundment. We
have no evidence that there is any tailing water lost to groundwater flows out of the
drainage area.
Page 16, fourth paragraph, second sentence should read:
Piezometers and open-ended standpipes are used to monitor stability in the
impoundment,
Page 17. second paragraph, second sentence should read:
Therefore, to ensure no discharge of seepage to Bruno Creek, a lined sump was j
installed further downstream in the Bruno Creek drainage.
Page 17, second paragraph, fifth sentence should read:
J
Seepage collected in both the seepage return pond and the downstream sump is
pumped back to the reclaim water head tank at the mill.
Page 18, second paragraph, last sentence should read:
Limited static testing performed on a whole tailings sample from which pyrite was
recovered indicated a NP/AP ratio in excess of 4:1 compared to an average value of
0.84:1 for all tailings analyses (Staffen Robertson & Kirsten 1991 a).
Mine Water
Page 18, last paragraph, second sentence should read:
However, groundwater seepage to the pit began in 1988 when the pit reached the
7,300 foot elevation fa depth of about 7,000 feet below the surface).
Page 18, last paragraph, fourth sentence should read:
According to Cyprus personnel, an average of 200 gpm of mine water is pumped
out of the pit to a booster station and pumped to the tailings pond.
B-6
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Site Visit Report: Cyprus Thompson Creek
Cyprus Minerals Co. Comments - Thompson Creek Report
JuneS, 1992
page?
Page 18, last paragraph, after above fourth sentence the following sentence should be .
added:
Because the miff was down during spring runoff of 1991, mine water was
combined with underflow collected from Pat Hughes Waste Rock dump and
discharged through NPDES outfall 002 after receiving approval from EPA.
Page 19, second footnote at the bottom of the page, the following sentence should be
added:
Laboratory contamination of the sample bottles is suspected as a source for the
anomalous mercury values.
Other Materials and Wastes-Waste Oil/Grease/Fuel
Page 20, second paragraph, fourth sentence should read:
Two 13,OOO underground tanks are used for gasoline storage. Waste oil is
collected in two above ground 10,000 gallon tanks near the shops.
Capacitor*
Page 20, last paragraph, should read:
Capacitors. Only one shipment of PCB contaminated capacitors was manifestetfand
shipped off-site since startup of the mine. According to Cyprus there is no '
remaining PCB- contaminated electrical equipment on the Thompson Creek Mine
property.
Regulatory Requirements and Compliance
Page 22, first paragraph, first sentence should read: /
Cyprus Thompson Creek operates under several permits and/orapprovals issued by
the State of Idaho Department of Lands, Division of Environmental Quality, and
Water Resources as well as approvals from the U.S. Forest Service (USFS) and EPA
Region X.
Page 22, first paragraph, third sentence should read:
The /nteragency task force for the Thompson Creek site meets quarterly and
includes representatives of the State Departments of Lands, Fish and Came,
Department of Water Resources, and Divison of Environmental Quality, USFS, and
BLM.
B-7
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Site Visit Report: Cyprus Thompson Creek
Cyprus Minerals Co. Comments Thompson Creek Report
June 5, 1992
page 8
Page 22, fourth paragraph, delete the second sentence that states:
However, because of the proximity of their offices, USFS personnel are at thf site.
almost daily.
Water Quality Monitoring
Page 23, second paragraph, second sentence should read:
Monitoring for pH and metals is required to ensure no degradation of surface and
ground water in the Salmon River basin (Cyprus 199 let.
Acid Rock Drainage Study
Page 23. third paragraph, last sentence should be replaced with the following two
sentences:
According to USFS personnel who participated in the site visit, the revisions to the
^an of Operations will be subjected to the environmental review requirements of
the National Environmental Policy Act (NEPAL This review may include the
preparation of a supplemental Environmental Impact Statement.
Bonding
Page 23, fifth paragraph, last sentence: Delete "and insurance." Cyprus has met its
bonding requirements through the posting of an appropriate surety bond. Our insurance
status has nothing to do with bonding.
NPDES PermH
Page 28, third paragraph, the second and third sentences should read:
This pond discharges to Squaw Creek at NPDES outfall 003. Cyprus is required to
monitor Squaw Creek upstnsam and downstream of this outfall for turbidity. "
Air Permit
Page 29, first bullet under Air Permit section should read:
Baghouses are located at the crusher, at the turning point of the conveyor, at the
lime bin, at the product package area, and at the HPM plant,
Page 29, fourth bullet, change the period at the end of the bullet to a comma.
Page 29, after fourth bullet, add fifth bullet stating:
B-8
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Site Visit Report: Cyprus Thompson Creek
Cyprus Minerals Co. Comments Thompson Creek Report
JuneS, 1992
page 9
Hotoflyte/Rotary kiln stack on HPM plant.
Dam Safety Permit
Page 29, third paragraph, first sentence should read:
As required under Idaho State law, Cyprus Thompson Creek has a dam safety
permit issued by the Department of Water Resources for the main tailings
embankment and the 3RD.
E-9
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Site Visit Report: Cyprus Thompson Creek
APPENDIX C
EPA RESPONSES TO CYPRUS MINERALS COMPANY COMMENTS
ON DRAFT SITE VISIT REPORT
-------
Site Visit Report: Cyprus Thompson Creek
EPA RESPONSES TO CYPRUS MINERALS COMPANY JUNE 5, 1992, COMMENTS ON
DRAFT MINE SITE VISIT REPORT: CYPRUS THOMPSON CREEK MINE
A copy of the draft Mine Site Visit: Cyprus Thompson Creek Mine was provided to Cyprus Minerals
Corporation for their review. EPA has addressed the comments submitted by Cyprus Thompson Creek (See
Appendix C) in the revised report as described below:
Comment 1: Cyprus provided clarifications of the titles and corrected telephone numbers for several of the
individuals who participated in the site visit.
Response:The text has been changed accordingly.
Comment 2:Cyprus clarified the ownership of specific areas of the property and indicated that the mine is 35
miles from Challis, ID.
Response:The text has been changed accordingly.
Comment 3:Cyprus clarified the general descriptions of the operations at the site.
Response:The text has been changed accordingly.
Comment 4'.Cyprus indicated that the draft report described a surface water body, Unnamed Creek, that is not
found at the site.
Response:References to Unnamed Creek have been deleted from the text and figures.
Comment 5: Cyprus indicated that the nearest drinking well is located at the Redbird Mine (3 miles from the
site) not at the Ranger Station (6 miles from the site).
Response:The text has been changed accordingly.
Comment 6:Cyprus clarified the history of operations including indicating that milling operations resumed in
November 1991.
Response:The report has been edited to reflect these change, including a parenthetical reference to the restart
of milling operations after the site visit in November 1991.
C-l
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Site Visit Report: Cyprus Thompson Creek
Comment 7:Cyprus provided a corrected elevations for the current and planned depths of the pit.
Response:The text has been changed accordingly.
Comment 8:Cyprus clarified the description of mining operations, indicating that waste oil was no longer
being used in the ANFO mixture (pending MSHA approval).
Response:
The text has been changed accordingly.
Comment 9:
Cyprus commented that while the stripping ratio was 4:1 in 1990, the average stripping ratio over the life
the time is expected to be closer to 2:1.
Response:
The report has been edited to indicate an average stripping ratio of 2:1 over life of the mine.
Comment 10:
Cyprus provided clarification of the description of milling operations, including specific information about
the HPM plant and the compositions of the high and lower, technical grade products. Cyprus further
indicated that there are two separate dryers (a dryer for the HPM concentrate and a dryer for the technical
grade concentrate). Cyprus noted that the gyratory crusher is equipped with a baghouse to control dust
emissions (not water sprays). Water sprays are used to control dust emission from the portable crusher
used to produce gravel.
Response:
The text has been changed accordingly.
Comment 11:
For the Buckskin dump, Cyprus provided corrected elevations for the top and bottom of the dump. In
their written comments, the elevation of the bottom of the Buckskin was inadvertently listed as 7,600 feet.
Cyprus was subsequently contacted telephone to clarify this information. Cyprus personnel indicated that
the Buckskin dump currently extends from 8,100 feet down to 6,800 feet. In addition, Cyprus personnel
noted that the has a second 300 foot wide bench at the 7,900 foot level. Cyprus further indicated that the
NALCO coagulant is added to the sedimentation ponds located downstream of the waste rock piles to
control TSS (not TDS).
C-2
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Site Visit Report: Cyprus Thompson Creek
Response:
The text has been changed accordingly.
Comment 12:
Cyprus summarized available acid base accounting data for the volcanic rocks.
Response:
The text has been changed accordingly.
Comment 13:
Cyprus clarified the annual quantity of tailings generated (based on full production and the current 10/4
mill operating schedule). Cyprus also corrected the frequency of concentrate and tailings analyses.
Response:
The text has been changed accordingly.
Comment 14:
Cyprus commented that the tailings pipeline is located in a ditch along it entire length to provide for
secondary containment.
Response:
The report has been edited to reflect this comment. The revised report continues to indicate that the ditch
is unlined.
Comment 15:
Cyprus requested deletion of the sentence "Cyprus personnel indicated that approximately 120 gpm of
tailings water is lost to infiltration."
\
Response:
This sentence has been deleted from the report.
Comment 16:
Cyprus indicated that open-ended standpipes are used along with piezometers to monitor stability in the
tailings impoundment.
C-3
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Site Visit Report: Cyprus Thompson Creek
Response:
The report has been edited to include this information.
Comment 17:
Cyprus indicated that the pumpback sump is lined (but not concrete) and that seepage collected in the SRD
and the sump are returned directly to the mill (not the tailings impoundment).
Response:
The text has been changed accordingly.
Comment 18:
Cyprus provided corrected data on acid base accounting of tailings from which pyrite was recovered.
Response:
The text has been changed accordingly.
Comment 19:
Cyprus clarified mine water generation and management, specifically indicating that mine water is
generally pumped to the tailings impoundment. Only during Spring 1991 (when the mill was shutdown),
mine water was combined with the.underflow from the Pat Hughes Dump and discharge through outfall
002 (with EPA's prior approval).
Response:
The text has been changed accordingly.
Comment 20:
Cyprus requested that the Footnote 1 in Table 2 indicate that Cyprus suspects that the "anomalous"
mercury values were caused by laboratory contamination.
Response:
The footnote now reflects Cyprus' suggestion that the elevated levels were caused by laboratory
contamination.
Comment 21:
Cyprus provided corrected volumes for several tanks. Cyprus further indicated that, during the life of the
C-4
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Site Visit Report: Cyprus Thompson Creek
mine, there has been only one shipment of PCBs manifested and disposed off-site. According to Cyprus,
there is no longer any PCB-contaminated electrical equipment at the site.
Response:
The text has been changed accordingly.
Comment 22:
Cyprus clarified the names of several State agencies that participate hi the interagency Task Force, and
requested deletion of the reference to USFS personnel visiting the site "almost daily."
Response:
The report has been edited to include the correct agency names and the reference to almost daily visits by
USFS personnel has been deleted.
Comment 23:
Cyprus changed a reference from the Salmon Creek basin to the Salmon River basin.
Response:
The text has been changed accordingly.
Comment 24:
Cyprus indicated that the revisions to the Plan of Operations to address acid rock drainage will require
NEPA review and may require a supplemental EIS.
Response:
The text has been changed accordingly.
Comment 25:
Cyprus indicated that their insurance status has no relation to their bonding.
Response:
The text has been changed accordingly.
Comment 26:
Cyprus clarified that the storm water sediment pond discharges to Squaw Creek, not Bruno Creek, and that
monitoring is required above and below the pond discharge in Squaw Creek.
C-5
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Site Visit Report: Cyprus Thompson Creek
Response:
The text has been changed accordingly.
Comment 27:
Cyprus indicated that their air permit addresses a total of five emission sources, including the stacks of
both holoflyte dryers/rotary kilns.
Response:
Both dryers have been identified as separate emission sources in the report. In addition, the section now
indicates that water sprays are used to control emissions from fhe portable crusher.
Comment 28:
Cyprus clarified that the Department of Water Resources is the issuing agency for their dam safety permit.
Response:
The text has been changed accordingly.
C-6 J
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