EPA 530-R-94-013
NTIS
TECHNICAL RESOURCE DOCUMENT
EXTRACTION AND BENEFICIATION OF
ORES AND MINERALS
VOLUME 2
GOLD
August 1994
U.S. Environmental Protection Agency
Office of Solid Waste
Special Waste Branch
401 M Street. SW
Washington. DC 20460
Recycled/Racyclable Printed with Vegetable Oil Based Inks on 100% Recycled Paper (50% Postconsumer) Please recycle as newsprint
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Technical Resource Document: Gold
DISCLAIMER AND ACKNOWLEDGEMENTS
This document was prepared by the U.S. Environmental Protection
Agency (EPA). The mention of company or product names is not to
be considered an endorsement by the U.S. Government or the EPA.
This Technical Resource Document consists of five sections. The first
section is EPA's Profile of the gold industry; the remaining four
sections are Site Visit Reports from site visits conducted by EPA.
The Profile Section was distributed for review to the U.S. Department
of the Interior's Bureau of Mines and Bureau of Land Management,
the U.S. Department of Agriculture's Forest Service, the Western
Governors Association, the Interstate Mining Compact Commission,
the American Mining Congress, and Environmental Public Interest
Groups. Summaries -of the comments and EPA's responses are
presented as an appendix to the Profile Section. The Site Visit Report
Sections were reviewed by individual company, state, and Federal
representatives who participated in the site visit. Comments and EPA
responses are included as Appendices to the specific Site Visit
Sections. 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 the Profile section of this document is not intended to
classify any waste streams for the purposes of regulatory interpretation
or application. Rather, these terms are used in the context of common
industry terminology.
U S Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12tn
Chicago, IL 60604-3590
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Technical Resource Document: Gold
TABLE OF CONTENTS .
Page
1.0 MINING INDUSTRY PROFILE: GOLD 1-1
1.1 INTRODUCTION , , 1-1
1.2 ECONOMIC CHARACTERIZATION OF THE INDUSTRY * . . 1-3
1.3 ORE CHARACTERIZATION 1-6
1.3.1 Types of Gold Ore Deposits 1-7
1.3.1.1 Sediment-Hosted Disseminated Gold 1-7
1.3.1.2 Volcanic-Hosted Epithennal Deposits 1-7
1.3.1.3 Porphyry Copper-Related Deposits 1-7
1.3.1.4 Greenstone Gold .Quartz Vein Deposits 1-8
1.3.2 Mineral Content . 1-8
1.4 GOLD EXTRACTION AND BENEFICIATION PRACTICES 1-11
1.4.1 Extraction Methods 1-11
.4.1.1 Surface Mining 1-13
.4.1.2 Underground Mining 1-14
1.4.2 Beneficiation Methods 1-14
.4.2.1 By-Product Gold (Flotation) 1-14
.4.2.2 Gravity Concentration 1-16
.4.2.3 Amalgamation 1-16
.4.2.4 Cyanidation 1-17
1.5 EXTRACTION AND BENEFICIATION WASTES ASSOCIATED WITH
GOLD OPERATIONS '. 1-39
1.5.1 Extraction and Beneficiation Wastes 1-40
1.5.1.1 Waste Rock from Mining , . 1-40
1.5.1.2 Mine Water . . . . . 1-40
1.5.1.3 Spent Ore From Heap Leaching 1-41
1.5.1.4 Spent Ore from Tank Leaching (Tailings) 1-41
1.5.1.5 Barren Cyanide Solution 1-41
1.5.1.6 Zinc Precipitation Wastes 1-42
1.5.1.7 Wastes From Carbon Regeneration 1-42
1.5.1.8 Amalgamation Wastes 1-42
1.5.2 Waste Management 1-42
1.5.2.1 Waste Rock Piles 1-43
1.5.2.2 Mine Pits and Underground Workings . . .... .... 1-43
1.5.2.3 Tailings Impoundments 1-43
1.5.2.4 Spent Ore Piles 1-44
1.6 ENVIRONMENTAL EFFECTS 1-45
1.6.1 Ground Water/Surface Water 1-45
1.6.1.1 Acid Generation l^S
1.6.1.2 Mine Dewatering 1-46
1.6.1.3 Release of Cyanide Solution From Active Heap Leach Units ... 1-46
1.6.1.4 Release From Heap Leach Piles During and After Closure. ..
(Reclamation) . : .;,... 1-47
1.6.2 Soil '. 1-48
1.6.2.1 Land Application of Spent Cyanide Solution ...... 1-48
1.6.2.2 Detoxification of Cyanide l-*8
1.6.3 Air.. ..;... , 1-50
1.6.'3.1 FugitiveDust , . 1-50
1.6.4 Damage Cases .^. 1-50
1.6.4.1 National Priorities List 1-50
11
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Technical Resource Document:
1.6.4.2 3040) Sites '. 1-51
1.6.4.3 Other Reported Damage Cases (Grey Eagle Mine, Sisltiyou
County, California) 1-51
1.7 CURRENT REGULATORY AND STATUTORY FRAMEWORK 1-53
1.7.1 Environmental Protection Agency Regulations 1-53
1.7.1.1 Resource Conservation and Recovery Act . 1-53
1.7.1.2 Clean Water Act 1-55
1.7.1.3 Clean Air Act 1-57
1.7.2 Department of Interior 1-59
1.7.2.1 Bureau of Land Management 1-59
1.7.2.2 National Park Service and Fish and Wildlife Service 1-61
1.7.3 Department of Agriculture; Forest Service 1-61
1.7.4 Army Corps of Engineers ; 1-62
1.7.5 STATE REGULATIONS 1-63
1.7.5.1 Nevada 1-63
1.7.5.2 South Carolina 1-66
1.8 REFERENCES . 1-69
2.0 Srre Visrr REPORT: BREWER MINE 2-1
2.1 INTRODUCTION 2-1
2.1.1 Background ; 2-1
2.1.2 General Facility Description . . 2-2
2.1.3 Environmental Setting 2-4
2.1.3.1 Surface Water 2-4
2.1.3.2 Geology . . . .. 2-5
2.1.3.3 Hydrogeology 2-6
2.2 FACILITY OPERATIONS 2-7
2.2.1 Mining Operations 2-7
2.2.2 Beneficiation Operations 2-8
2.2.3 Chemical Usage 2-12
2.3 MATERIALS AND WASTE MANAGEMENT 2-13
2.3.1 Mine Pit and Water 2-13
2.3.2 Waste Rock Pile 2-14
2.3.3 Leach Pads and Spent Ore 2-15
2.3.4 Sediment Pond 2-18
2.3.5 Pad 6 Overflow Pond 2-20
2.3.6 Solution Ponds . . . 2-21
2.3.7 Other Wastes 2-23
2.4 REGULATORY REQUIREMENTS AND COMPLIANCE 2-24
2.4.1 South Carolina Department of Health and Environmental Control 2-24
2.4.1.1 Bureau of Water Pollution Control 2-24
2.4.1.2 Bureau of Air Quality Control 2-30
2.4.2 Land Resources Commission .' 2-37
2.4.2.1 Division of Mining and Reclamation Mining Permit 671 2-37
' > 2.4.2.2 Engineering Division Dam Construction and Repair Permits . . . 2-39
2.4.3 Other Regulatory Agencies and Permits 2-39
2.5 REFERENCES 2-40
3.0 SITE Visrr REPORT: COLOSSEUM MINE 3-1
3.1 INTRODUCTION '. 3-1
3.1.1 Background 3-1
3.1.2 General Facility Description 3-2
3.1.3 Environmental Setting 3-4
111
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Technical Resource Document: Gold
3.1.4 Geology .......... * ...... ........................... 3-6
3.1.5 Surface Water ..... .................................. 3-8
3.1.6 Ground Water ....................................... 3-9
3.2 FACILITY OPERATIONS ................................ .... 3-13
3.2.1 Mining ...... . .. ..... ........... . . ; ........... . ______ 3-13
3.2.2 Beneficiation .................... . .................. 3-15
3.2.2.1 Crushing and Grinding ........................... 3-15
3.2.2.2 Carbon-In-Pulp ............................... 3-19
3.2.2.3 Carbon Stripping ......................... ....;. 3-19
3.2.2.4 Electrowinning, Electrorefining, and Smelting ............ 3-20
3.3 MATERIALS AND WASTE MANAGEMENT ............ . .......... 3-22
3.3.1 Waste Rock Piles .................................... 3-22
3.3.2 Low-Grade Stockpile .................................. 3-24
3.3.3 Open Pits ......................................... 3-24
3.3.4 Cyanide Destruction Reactor .... ......................... 3-25
3.3.5 Tailings Impoundment ................ . ................ 3-25
3.3.6 Other Wastes ...................... . . ............... 3-31
3.4 REGULATORY REQUIREMENTS AND COMPLIANCE ................ 3-32
3.4.1 Bureau of Land Management ............................. 3-32
3.4.2 California Department of Conservation, Division of Mines and Geology . . 3-33
3.4.3 California Regional Water Quality Control Board, Lahontan Region ..... 3-34
3.4.3.1 Cyanide Detoxification Facility (INCO) ................ 3-35
3.4.3.2 Tailings Impoundment ........................... 3-35
3.4.3.3 Waste Rock Piles ........................ . ..... 3-36
3.4.3.4 General Requirements ........................... 3-36
3.4.4 Air Pollution Control District, San Bernardino County ............. 3-39
3.4.5 Other Permits ........................... . .......... 3-39
3.5 REFERENCES ............ ................................ 3-42
4.0 SITE Visrr REPORT: NERCO MINERALS CRIPPLE CREEK ....................... 4-1
4.1 INTRODUCTION ....................... ............. . ...... 4-1
4.1.1 Background ..................................... .. . . . 4-1
4.1.2 General Facility Description ............. ......... . ....... 4-2
4.1.3 Environmental Setting .................................. 4-6
4.1.3.1 Climate ...................................... 4-6
4.1.3.2 Surface Water ...................... . .......... 4-6
4.1.3.3 Ground Water ................................. 4-7
4.1.3.4 Vegetation ................................... 4-8
4.1.3.5 Soils ....................................... 4-8
4.1.3.6 Geology . .................................... 4-8
4.2 FACILITY OPERATIONS ..... . .............................. 4-10
4.2.1 Mining Operations . . . . , ................. . ........ '. - 4-10
4.2.2 .: Leaching Operations ..................... . ............ 4-13
4.2.3 Gold Recovery Operations .............................. 4-15
4.3 MATERIALS AND WASTE MANAGEMENT ............ . .......... 4-17
4.3.1 Mine Pits ................................... ...... 4-17
4.3.2 Waste Rock Dump ....................... : ........... 4-18
4.3.3 Heap Leach Pads and Ponds, Permit 77-367 (Globe Hill Projects) ...... 4-19
4.3.3.1 Globe Hill Pad and Ponds ......................... 4-20
4.3.3.2 Forest Queen/2A Heap Leach Pad(s) and Pond(s) . . ........ 4-22
4.3.4 Victor Tailings Piles and Previous Vat Leach Operation (Permit 81-134) . . 4-24
4.3.5 Ironclad Heap Leach Pads and Ponds (Permit 81-134) ............. 4-30
4.3.5.1 Heap Leach Pads .............................. 4-32
IV
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Technical Resource DocumeiU^ GcU
4.3.5.2 Solution Ponds .. . 4-39
4.3.5.3 Wastes and Other Materials Managed by Nerco 4-40
4.4 OTHER MAJOR CRIPPLE CREEK OPERATIONS 4-43
4.4.1 Carlton Mill (Pads 1 and 2) 4-43
4.4.2 Victory Project (Pads 3 and 4) 4-45
4.4.3 '76 (Bull Hill) Project 4-48
4.5 REGULATORY REQUIREMENTS AND COMPLIANCE 4-51
4.5.1 Colorado Mined Land Reclamation Division .. 4-51
4.5.2 Colorado Department of Health, Water Quality Control Division . 4-55
4.5.3 Colorado State Engineer, Division of Water Resources 4-64
4.5.4 Other Permits 4-64
4.6 ANNOTATED LIST OF REFERENCES 4-67
5.0 SUE Visrr REPORT: DOE RUN FLETCHER 5-1
5.1 INTRODUCTION . 1 5-1
5.1.1 Background 5-1
5.1.2 General Description 5-2
5.1.3 Environmental Setting 5-5
5.1.3.1 Climate 5-5
5.1.3.2 Geology . 5-6
5.1.3.3 Hydrology 5-9
5.2 FACILITY OPERATIONS 5-11
5.2.1 Mining Operations .- 5-12
5.2.2 Mill Operation 5-15
5.2.3 Heap Leach 5-19
5.2.4 Facility Control Room 5-23
5.3 MATERIALS AND WASTE MANAGEMENT 5-25
5.3.1 Mine Pit and Heap Leach 5-25
5.3.2 Waste Rock Dump 5-26
5.3.3 Tailings Impoundment 5-30
5.3.4 Water Management 5-39
5.3.5 Other Materials and Wastes 5-40
5.4 REGULATORY REQUffiEMENTS AND COMPLIANCE 5-42
5.4.1 State of Nevada 5-42
5.4.1.1 Reclamation Permit 5-42
5.4.1.2 Water Permits 5-42
5.4.1.3 Air Permits 5-45
5.4.2 Plan of Operations (Bureau of Land Management) 5-48
5.4.3 Hazardous Waste (U.S. Environmental Protection Agency) 5-48
5.5 REFERENCES 5-49
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Technical Resource Document: Gold
APPENDICES
APPENDIX 1-A FLOW SHEETS OF SPECIFIC MINE OPERATIONS 1-74
APPENDIX 1-B NPL SITE SUMMARIES RELATED TO GOLD EXTRACTION AND
BENEFICIATION 1-79
APPENDIX 1-C 304(1) SITES RELATED TO GOLD MINING ACTIVITIES 1-90
APPENDIX 1-D COMMENTS AND RESPONSES 1-92
APPENDIX 1-E ACRONYM LIST 1-%
APPENDIX 2-A COMMENTS SUBMITTED BY BREWER GOLD COMPANY
ON DRAFT SITE VISIT REPORT 2-46
APPENDIX 2-B COMMENTS SUBMITTED BY SOUTH CAROLINA
DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL
ON DRAFT SITE VISIT REPORT . 2-48
APPENDIX 2-C COMMENTS SUBMITTED BY SOUTH CAROLINA LAND RESOURCES
COMMISSION ON DRAFT SITE VISIT REPORT ' 2-50
APPENDIX 2-D EPA RESPONSES TO BREWER GOLD COMPANY COMMENTS ON DRAFT
SITE VISIT REPORT 2-52
APPENDIX 2-E EPA RESPONSE TO COMMENTS SUBMITTED BY SOUTH CAROLINA
DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL AND
SOUTH CAROLINA LAND RESOURCES COMMISS ION ON DRAFT SITE
VISIT REPORT . . 2-54
APPENDDC 3-A COMMENTS SUBMITTED BY COLOSSEUM ON DRAFT SITE VISIT
REPORT 3-45
APPENDIX 3-B EPA RESPONSE TO COMMENTS SUBMITTED BY COLOSSEUM INC. . . 3-47
APPENDIX 4-A PERMIT HISTORY OF THE CARLTON MILL HEAP LEACH PADS (MLRD
PERMIT 80-244) 4-82
APPENDIX 4-B PERMIT HISTORY OF THE VICTORY PROJECT (MLRD PERMIT 86-024) 4-87
APPENDDC 4-C COMMENTS SUBMITTED BY NERCO MINERALS COMPANY ON
DRAFT SITE VISIT REPORT 4-92
APPENDIX 4-D EPA RESPONSE TO COMMENTS SUBMITTED BY NERCO MINERALS
COMPANY ON DRAFT SITE VISIT REPORT 4-94
APPENDIX 5-A FLOW CHARTS OF THE RAIN MINE, MILL, HEAP LEACH, AND TAILINGS
PROCESSES 5-52
APPENDIX 5-B CHEMICAL ANALYSIS OF FIVE SITES ALONG EMIGRANT SPRINGS . . 5-57
APPENDDC 5-C CHEMICAL ANALYSIS OF METEORIC WATER MOBILITY TEST FOR THE
THIRD AND FOURTH QUARTERS OF 1990, AND THE FIRST QUARTER OF
1991 5-65
APPENDDC 5-D QUARTERLY MONITORING DATA FOR 1988 AND 1989 FOR SELECTED
MONITORING WELLS AND THE SEEPAGE COLLECTION POND 5-67
APPENDDC 5-E COMMENTS SUBMITTED BY NEWMONT GOLD COMPANY ON
DRAFT SITE VISIT REPORT 5-77
APPENDIX 5-F EPA RESPONSE TO COMMENTS SUBMITTED BY NEWMONT GOLD
COMPANY . :. . . 5-79
VI
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Technical Resource Document: Gold
LIST OF TABLES
Table 1-1. Twenty-Five Leading Gold-Producing Mines in the United States, 1991,in
Order of Output 1-4
Table 1-2. U.S. Consumption of Gold*, by End Use Sectork 1-5
Table 1-3. Spectrographic Analyses of Samples of Various Types of Unoxidized
Ores, Oxidized and Leached-Oxidized Ores, Carlin Gold Deposit,
Lynn Window, Eureka Co., NV ...;...... 1-9
Table 1-4. Crude Ore, Waste, and Marketable Product at Surface
and Underground Gold Mines, 1988 1-13
Table 1-5. Comparison of Gold Ore Treated and Gold Product by Beneficiation Method, 19911-16
Table 1-6. Heap Leach Regulatory Requirements for the 15 Gold-Producing States 1-54
Table l-7a. BPT and BAT Standards for the Ore Mining and Dresing Point-Source Category:
Copper, Lead, Zinc,Gold, Silver, and Molybdenum Ore Subcategory Concentration
of Pollutants Discharged in Mine Drainage (milligrams per liter) 1-56
Table l-7b. BPT and BAT Standards for the Ore Mining Dressing Point Source Category:
Copper, Lead, Zinc, Gold, Silver and Molybdenum Ore Subcategory
Concentration of Pollutants Discharged From Mills That Use the-Froth-Flotation
Process Alone or hi Conjunction With Other Processes for Beneficiation
(milligrams per liter) ". . 1-56
Table 1-8. Federal Water Quality Criteria and Drinking Water MCL* (mg/l) "...'.. .v. ... 1-57
Table 2-1. Brewer Gold Company Chemical Purchases, January - September 1991 2-12
Table 2-2. Concentrations of Selected Parameters hi Discharges from Outfalls 001 and 0021 2-19
Table 2-3. Other Wastes and Management Practices, Brewer Gold Company 2-23
Table 2-4. Effluent Limits1 in Brewer Gold Company NPDES Permit SC0040657 2-25
Table 2-5. Construction Permits Issued to Brewer Gold Company 2-27
Table 2-6. Monitoring Data From Wells Located Near Sediment Pond and Waste Rock
Disposal Area 2-32
Table 2-7. Monitoring Data From Wells Located Near Solution Ponds . . . 2-33
Table 2-8. Monitoring Data From Wells Located Near Leach Pad 6 2-34
Table 2-9. Monitoring Data From Well Located Near Pad 6 Overflow Pond and From
Pad 6 Overflow Pond Underdrain : . . . 2-35
Table 2-10. Groundwater Monitoring Data From Well Located Near Topsoil Stockpiling Area2-35
Table 2-11. Emission Limits Established by Permit 0660-0066 '. 2-36
Table 2-12. Emission Limits Established by Permit 0660-0026-CE 2-36 '
Table 2-13. Major Requirements Established by Mine Permit 671 2-38
Table 2-14. Dam Construction and Repair Permits Issued to Brewer Gold Company 2-39
Table 3-1. -Concentrations of Selected Constituents from Quarterly Samples of Ground Water
Extracted From the Ivanpah Valley Aquifer .v 3-12
Table 3-2. Chemical Analysis of Tailings Solids - Common Mineral Components
(Unprocessed Ore Analysis) : ".'. 3-26
Table 3-3. Minor and Trace Constituents of Colosseum Tailings Solids 3-17
Table 3-4. Comparison of Original Estimate of Tailings Liquid Composition and
Actual Annual Tailings Water Analyses ...:........ t-28
Table 3-5. Results of Required Ground Water at the Colosseum Mine . . ..;. ..... V *H
Table 3-6. Air Pollution Control Permits
VII
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Technical Resource Document: Gold
Table 4-1. Concentrations of Selected Parameters in Globe Hill Heap Pond 4-21
Table 4-2. Concentrations of Selected Parameters in Forest Queen/2A Heap Pond 4-23
Table 4-3. Concentrations of Selected Parameters in Tailings Collection Ponds 4-27
Table 4-4. Concentrations of Selected Constituents in Vat Leach Tailings and
Tailings Seepage Ponds 4-29
Table 4-5. Monitoring Results from Pad 1 French Drain and from Arequa Gulch Upstream and
Downstream of Pads 1 and 2 '. ,4-46
Table 4-6. Concentrations of Selected Parameters in '76 Project Barren and
Pregnant Solution Ponds 4-50
Table 4-7. Colorado Mined Land Reclamation Division Permits Issued to Nerco* ....... 4-53
Table 4-8. Permit History of the Victor Mine (MLRD Permit 81-134) 4-56
Table 4-9. Permit History of the Globe Hill Project (MLRD Permit 77-367) 4-59
Table 4-10. Discharge Limitations and Monitoring Data for Carlton Tunnel 4-65
Table 4-11. Other Permits Issued to Nerco Minerals for Cripple Creek Operations 4-66
Table 5-1. Analysis of Reclaim Water Returned to the Mill from the Tailings Impoundment 5-16
Table 5-2. Analysis of Mill Water 5-17
Table 5-3. Analysis of Tailings Water , 5-20
Table 5-4. Analysis of Barren Solution 5-22
Table 5-5. Analysis of Pregnant Solution 5-24
Table 5-6. Projected Waste Rock Generation (Waste Tonnages X 1000) 5-26
Table 5-7. Analysis of Seepage Pond Water (CP) 5-35
Table 5-8. Analysis of Underdrainage Water 5-38
Table 5-9. Chemical Analyses of Tailings Solids for First Three Quarters, 1990 5-39
Table 5-10. Selected Wastes and Materials Handled at Rain Facility . . . . . 5-41
Table 5-11. State and Federal Permits and Approvals, Ram Facility 5-43
Table 5-12. Permit NEV87011: Monitoring Locations, Parameters, and Frequencies 5-46
Table 5-13. Discharges from Monitoring Locations Reported in Quarterly Monitoring Reports 5-47
Table 5-14. Acid Rock Drainage Sampled Below Waste Rock Dump, Sample Location 1,
Rain Facility, May and July, 1990 . 5-59
Table 5-15. Acid Rock Drainage Sampled Below Waste Rock Dump, Sample Location 2,
Rain Facility, May and July, 1990 5-60
Table 5-16. Surface Water Quality Data in Emigrant Springs, May and July, 1990 5-61
Table 5-17. Surface Water Quality Data in Emigrant Springs Below EMIG-3,
May and July, 1990 5-62
Table 5-18. Surface Water Quality Data Below EMIG-3, May and July, 1990 5-63
Table 5-19.-Water Quality and Sediment Data, Rain Facility, June 15, 1990 . 5-64
Table 5-20. Monthly Average for Selected Sample Results, Rain Facility, 1988 5-68
Table 5-21. Monthly Average for Selected Sample Results, Rain Facility, 1989 5-70
vm
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Technical Resource Document: Gold
LIST OF FIGURES
Page
Figure 1-1. Gold Extraction and Beneficiation Overview ; 1-12
Figure 1-2. Typical Surface Mine and Heap Leach Operation 1-15
Figure 1-3. Flowsheet for Recovery of Gold Using Carbon Adsorption
(Source: Van Zyl, et al. 1988.) 1-19
Figure 1-4. Typical Heap Leaching System
(Source: U.S. DOI, Bureau of Mines 1984.) 1-22
Figure 1-5. Typical On-Off and Life Pad Liner Construction Materials
(Source: Van Zyl, D.J.A., et al. 1988.) 1-24
Figure 1-6. Typical Fixed-Bed Multiple Carbon-In-Column Operation
(Source: Society of Mining Engineers, Mineral Processing Handbook 1985.) .... 1-28
Figure 1-7. Hypothetical Distribution of Gold in a Continuous Carbon Adsorption Operation
(Source: U.S. DOI, Bureau of Mines 1978.) . 1-29
Figure 1-8. Merrill-Crowe Recovery System
(Source: Van Zyl, et al. 1988.) 1-32
Figure 1-9. Typical Carbon-in-Pulp (CEP) Circuit
(Source: Calgon, Granular Carbon for Gold Recovery undated.) 1-34
Figure 1-10. Typical Carbon-in-Leach (CIL) Circuit 1-36
Figure 1-11. Typical In Situ Leaching Systems for Exposed and Buried Ore Bodies
(Source: U.S. DOI, Bureau of Mines 1984.) 1-38
Figure 1-12. Goldstrike Oxide Circuit 1-75
Figure 1-13. Goldstrike Heap Leach Circuit 1-76
Figure 1-14. Mercur Gold Mine, General Mining Operation 1-77
Figure 1-15. Sleeper Gold Mine, General Mining Operation 1-78
Figure 2-1. Location of Brewer Gold Mine
(Source: Figure 1 in Brewer Gold Company, 1990b) 2-3
Figure 2-2. Brewer Gold Company Simplified Flowsheet 2-9
Figure 2-3. Location of Facility Operations, Brewer Gold Mine 2-10
Figure 2-4. Location of Monitoring Wells, Brewer Gold Mine 2-31
Figure 3-1. Location of Colosseum Mine
(Source: Bureau of Land Management, et al., 1985a) 3-3
Figure 3-2. Topographic Setting of the Colosseum Mine
(Source: Bureau of Land Management, et al., 1985a) 3-5
Figure 3-3. Colosseum Site Geology
(Source: Bureau of Land Management, et al., 1985a) 3-7
Figure 3-4. Locations of Wells and Springs Near the Tailings Impoundment and in Colosseum
Gorge (Source: Steffen Robertson and Kirsten, 1987) . . . 3-11
Figure 3-5. General Site Map of the Colosseum Mine
(Source: Colosseum, Inc., 1989a) . . 3-14
Figure 3-6. Colosseum Mill Facility Map
(Source: Colosseum, Inc., 1989b) 3-16
Figure 3-7. Colosseum Mill Flow Chart
(Source: Bond Gold Colosseum, Inc., Undated) . 3-17
Figure 3-8. Life of Mine Statistics
(Source: Colosseum Inc., Undated) J--3
IX
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Technical Resource Document: Gold
Figure 4-1. Cripple Creek and Victor, Colorado, and Major Nerco Operations
(Source: Map used in numerous permit applications, modified by EPA) 4-3
Figure 4-2. Location of Mined Land Reclamation Division Permit Areas Controlled by Nerco
(Source: Provided by Nerco during site visit) 4-5
Figure 4-3. Location of Ironclad/Globe Hill Facilities (MLRD Permits 77-367 and 81-134)
(Source: Provided by Nerco during site visit, with additional labels added by EPA) 4-11
Figure 4-4. Planned Final Configuration of Ironclad Heap
(Source: Nerco 5/10/91, with additional labels added by EPA) 4-14
Figure 4-5. Location and Phases of Construction of the Ironclad Heap Leach Pad
(Source: Nerco 5/10/91, with additional labels added by EPA) 4-31
Figure 4-6. Planned Final Configuration of Phase I Portion of Ironclad Pad
(Source: Nerco 5/10/91, with additional labels added) 4-33
Figure 4-7. Ironclad Pad Liner and Internal Berm Construction
(Source: Nerco 5/10/91) 4-34
Figure 4-8. Planned Final Configuration of Phase II Portion of Ironclad Pad
(Source: Nerco 5/10/91, with additional labels added by EPA) 4-36
Figure 4-9. Planned Final Configuration of Ironclad Heap Leach Pad
(Source: Nerco 5/10/91, with additional labels added by EPA) 4-38
Figure 5-1. Site Location Map
(Source: SRK 1990) . . 5-3
Figure 5-2. Location of Rain Facilities
(Source: Newmont Gold Company) -. 5-4
Figure 5-3. Pit Geology (Source: SRK 1990) 5-7
Figure 5-4. Cross Section of Rain Pit, Section 1800SE (Source: SRK 1990) ." . 5-8
Figure 5-5. Rain Facility Flow Chart 5-13
Figure 5-6. Percent of Carbonaceous and Other Waste Rock in Waste Rock Dump 5-27
Figure 5-7. 1990 Tailings Facility Expansion '.- 5-31
Figure 5-8. Location of Monitoring Wells Below Tailings Impoundment 5-33
Figure 5-9. 1990 Tailings Facility Expansion, Main Embankment Plan , 5-37
Figure 5-10. Flowchart of the Ram Mine 5-53
Figure 5-11. Flowchart of the Rain Mine Mill 3 Process 5-54
Figure 5-12. Flowchart of the Heap Leach Process 5-55
Figure 5-13. Flowchart of the Ram Mine Tailing Process 5-56
Figure 5-14. Surface Water Monitoring Stations Along Emigrant Springs 5-58
-------
Mining Industry Profile: Gold
1.0 MINING INDUSTRY PROFILE: GOLD
1.1 INTRODUCTION
This Industry Profile presents the results of U.S. Environmental Protection Agency (EPA) research
into the domestic gold mining industry and is one of a series of profiles of major mining sectors.
Additional profiles describe lead/zinc mining, copper mining, iron mining, and several .industrial
mineral sectors, as presented in the current literature. EPA has prepared these profiles to enhance
and update its understanding of the mining industry and to support mining program development by
the states. EPA believes the profiles represent current environmental management practice as
described in the literature. ,
Each profile addresses extraction and beneficiation of ores. The scope of the Resource Conservation
and Recovery Act (RCRA) as it applies to mining waste was amended in 1980 when Congress passed
the Bevill Amendment, Section 3001(b)(3)(A). The Bevill Amendment states that "solid waste from
the extraction, beneficiation, and processing of ores and minerals" is excluded from the definition of
hazardous waste under Subtitle C of RCRA (40 CFR 261.4(b)(7)). The exemption was conditional
upon EPA's completion of studies required by RCRA Section 8002(f) and (p) on the environmental
and health consequences of the disposal and use of these wastes. EPA segregated extraction and
beneficiation wastes from processing wastes. EPA submitted the initial results of these studies in the
1985 Report to Congress: Wastes from the Extraction and Beneficiation of Metallic Ores, Phosphate
Rock, Asbestos, Overburden From Uranium Mining, and Oil Shale (U.S. EPA 1985). In July 1986,
EPA made a regulatory determination that regulation of extraction and beneficiation wastes under
Subtitle C was not appropriate (51 FR 24496; July 3, 1986). EPA concluded that Subtitle C controls
were unnecessary and found that a wide variety of existing Federal and State programs already
addressed many of the risks posed by extraction and beneficiation wastes. Instead of regulating
extraction and beneficiation wastes as hazardous wastes under Subtitle C, EPA indicated that these
wastes should be controlled under Subtitle D of RCRA.
EPA reported their initial findings on wastes from mineral processing from the studies required by the
Bevill Amendment in the 1990 Report to Congress: Special Wastes From Mineral Processing (U.S
EPA 1990). This report covered 20 specific mineral processing wastes; none involved gold
processing wastes. In June 1991, EPA issued a regulatory determination (56 FR 27300) stating thai
regulation of these 20 mineral processing wastes as hazardous wastes under RCRA Subtitle C is
inappropriate or infeasible. Eighteen of the wastes are subject to applicable state requirements. The
remaining two wastes (phosphogypsum and phosphoric acid process waste water) are currently being
evaluated under the authority of the Toxic Substances Control Act (TSCA) to investigate pollution
prevention alternatives. Any mineral processing wastes not specifically included in this list of 20
wastes no longer qualifies for the exclusion (54 FR 36592). Due to the timing of this decision and
1-1
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Mining Industry Profile: Gold
the limited numbers of industry wastes at issue, gold processing wastes are not addressed in this
profile.
In addition to preparing profiles, EPA has undertaken a variety of activities to support state mine
waste programs. These activities include visits to a number of mine sites; compilation of data from
State regulatory-agencies on waste characteristics, releases, and environmental effects; preparing
summaries of mining-related sites on the Superfund National Priorities List (NPL); and an
examination of specific waste management practices and technologies. Site visit reports are presented
as later sections of this Technical Resource Document. EPA has also conducted studies of State
mining-related regulatory programs and their implementation.
The purpose of this Profile is to provide additional information on the domestic gold mining industry.
The report describes gold extraction and beneficiation operations with specific reference to the wastes
associated with these operations. The Profile is based on literature reviews and on comments
received on earlier drafts. This Profile complements, but was developed independently of, other EPA
activities, including those described above.
This Profile briefly characterizes the geology of gold ores and the economics of the industry.
Following this discussion is a review of gold extraction and beneficiation methods; this section
provides the context for descriptions of wastes and materials managed by the industry, as well as a
discussion of the potential environmental effects that may result from gold mining. The Profile
concludes with a description of the current regulatory programs that apply to the gold mining industry
as implemented by EPA, Federal land management agencies, and selected States.
1-2
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Mining Industry Profile: Gold
1.2 ECONOMIC CHARACTERIZATION OF THE INDUSTRY
In 1990, U.S. gold operations produced 9.5 million troy ounces of gold from ore, valued at $3.6
billion. This represented an increase of 10 percent over the amount of gold produced domestically in
1989. Production levels in 1991 were 9.3 million ounces of gold; production for 1992 was estimated
to be 10.3 million troy ounces (U.S. DOI, Bureau of Mines 1992). Prior to 1990, a significant
portion of market demand was satisfied by importing refined products (U.S. DOI, Bureau of Mines
1990a). By contrast, the Gold Institute is projecting an $8 billion surplus in domestic production
between 1990 and 1994.
Historically, gold has been the principal medium of international monetary exchange, but its role has
changed significantly in recent years. Between 1934 and 1972, the United States monetary system
worked on a gold standard at a fixed rate of $35 per ounce. After leaving the gold standard in 1975
and allowing private ownership of the metal, the U.S. gold market grew rapidly and the price of gold
skyrocketed to a high of $850 per ounce in January 1980. Since that time, the price of gold has
dropped (U.S. DOI, Geological Survey 1973; U.S. DOI, Bureau of Mines 1985). Gold had an
average selling price of $438.31 per ounce in 1988 and is currently being traded at $360 to $400 per
ounce.
New gold mines continue to open (24 in 1989), and existing mines are expanding their production
capabilities. The United States is now the second largest gold producer in the world. In the 1993
Mineral Commodity Summaries, the Bureau estimates that the number of lode mines increased to 200
and that approximately 200 small placer operations were in operation, most in Alaska. The numbers
do not account for the thousands of "recreational" gold mines; these recreational mines are typically
operated by two to three individuals who may only work on weekends or on a seasonal basis.
Historically, gold has been mined in virtually every State but has been concentrated in the following
15: Alaska, Arizona, California, Colorado, Idaho, Michigan, Montana, Nevada, New Mexico, North
Carolina, Oregon, South Carolina, South Dakota, Utah, and Washington. State production figures
available for 1991 include Nevada (61 percent of newly mined domestic gold or 5.7 million troy
ounces), California (10 percent), Montana (6 percent), South Dakota (6 percent), Colorado (1
percent), Arizona (1 percent), Alaska (1 percent), and Idaho (1 percent). The 25 leading domestic
gold-producing mines (1991), in order of output, are listed in Table 1-1. In 1991, these mines
accounted for 68 percent of all domestically produced gold. According to the Bureau of Mines,
approximately 10 percent of gold production is generated as a by-product of other mining (U.S. DOI,
Bureau of Mines 1992, 1993).
According to the Bureau of Mines, gold industry employment has experienced a slight downturn since
1990. Employment at mines and mills was 16,000 in 1990 and was estimated to be 14,400 in 1992.
No data were available on employment at processing facilities (U.S. DOI, Bureau of Mines 1993).
1-3
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Mining Industry Profile: Gold
Table 1-1. Twenty-Five Leading Gold-Producing Mines in the United States, 1991,
in Order of Output
Rank
ll
2
2
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
' ;;' Mihe:":
Nevada Mines Operations
Goldstrike
Bingham Canyon
Jerritt Canyon (Enfield
Bell)
Smoky Valley Common
Operation
Homestake
McCoy and Cove
McLaughlin
Chimney Creek
Fortitude and Surprise
Bulldog
Mesquite
Getchell
Sleeper
Cannon
Ridgeway
Jamestown
Paradise Peak
Rabbit Creek
Barney's Canyon
Continental
Zortman-Landusky
Golden Sunlight
Wind Mountain
Foley Ridge & Amie Creek
County and State
Elko and Eureka, NV
Eureka, NV
Salt Lake, UT
Elko, NV
Nye, NV
Lawrence, SD
Lander, NV
Napa, CA
Humboldt, NV
Lander, NV
Hye, NV
Imperial, CA
Humboldt, NV
Humboldt, NV
Chelan, WA
Fairfield, SC
Tuolumne, CA
Nye, NV
Humboldt, NV
Salt Lake City, UT
Silver Bow, MT
Phillips, MT
Jefferson, MT
Washoe, NV
Lawrence, SD
Operator
Newmont ,Gold Co.
Barrick Mercur Gold Mines, Inc.
Kennecott-Utah Copper Corp.
Freeport-McMoran Gold Co.
Round Mountain Gold Corp.
Homestake Mining Co.
Echo Bay Mining Co.
Homestake Mining Co.
Gold Fields Mining Co.
Battle Mountain Gold Co.
Bond Gold, Bullfrog, Inc.
Goldfields Mining Co.
FMG, Inc.
Amax Gold, Inc.
Asamera Minerals (U.S.), Inc.
Ridgeway Mining Co.
Sonora Mining Corp.
FMC Gold Co.
Rabbit Creek Mining, Inc.
Kennecott Corp.
Montana Resources
Pegasus Gold, Inc.
Golden Sunlight Mines, Inc.
Amax Gold, Inc.
Wharf Resources
Source of
Gold
Gold Ore
Gold Ore
Copper Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Copper Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
'Modified at the request of Newmont Gold Co. to read Nevada Mines Operations instead of Carlin Mines Complex.
(Source: U.S. DOI, Bureau of Mines 1992.)
1-4
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Mining Industry Profile: Gold
Another trend in the gold industry has been joint exploration and/or production ventures between two
or more firms. An example of this trend is the recent agreement between Canyon Resources
Corporation and Kennecott Exploration Company to jointly mine a large California gold reserve. .
A general description of the typical domestic uses for gold products is shown in Table 1-2. From this
table, it can be seen that common end uses include jewelry and the arts, dental, and industrial
products. Although the majority of refined gold is used in jewelry manufacturing, gold is becoming
increasingly important in other industries. Gold has superior electric and thermal conductive abilities,
reflects infrared radiation and most of the visible spectrum, alloys easily with other metals, and resists
corrosion and tarnishing. These characteristics make gold valuable in high-technology products such
as computers, communications equipment, and spacecraft. In addition, gold has high malleability and
ductility, making it extremely easy to work with. In the electronics industry, gold is used in printed
circuit boards, connectors, keyboard contractors, miniaturized circuitry, and in some semiconductors
(U.S. DOI, Bureau of Mines 1992).
Table 1-2. U.S. Consumption of Gold", by End Use Sector1*
End Use
Jewelry and the Arts:
Karat Gold
Fine Gold for Electroplating
Gold-Filled and Other
Total
Dental
Industrial
Karat Gold
Fine Gold for Electroplating
Gold-Filled and Other
Total0
1991
(kilograms)
78,875
373
3,819
84,067
8,485
1,068
12,624
8,110
21,802
Small Items for Investment1
Grand Totalc
114,354
Gold consumed in fabricated products only; does not include monetary bullion.
''Data may include estimates.
T>ata may not add to totals shown because of independent roundng
"Fabricated bars, medallions, coins, etc.
(Source: U.S. DOI, Bureau of Mines 1992.)
1-5
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Mining Industry Profile: Gold
1.3 ORE CHARACTERIZATION
Gold occurs in a variety of geologic environments. Estimates of average abundance in the Earth's
crust are on the order of 0.003 to 0.004 parts per million (ppm) (U.S. DOI, Geological Survey
1973). Deposits considered to be economically recoverable at current market prices may contain as
little as 0.69 to 1.37 ppm [0.02 to 0.04 troy ounces of gold per ton of rock (oz/t)], depending on the
mining method, total reserves, and the geologic setting of the deposit.
Geologic processes act to concentrate gold into minable ore deposits. All gold deposits, except placer
deposits, are formed by hydrothermal processes. Hydrothermal systems form in numerous geologic
environments, ranging from dynamic systems associated with magmatic intrusives to low-energy
systems associated with deep fluid circulation heated by geothermal heat flow. Deposits formed from
.hydrothermal systems flowing at or near the surface (1,000 to 2,500 feet deep) are called epithermal
deposits, while those formed deeper are called mesothermal deposits. Combinations of the various
types of hydrothermal systems in various host rocks create variations in deposit morphology, grade
ranges (variation in gold content), and wall rock alteration. Deposit morphology ranges in a
continuum from veins several feet thick and hundreds to thousands of feet in vertical and lateral
dimensions (formed by mineral precipitation in voids in the host rock) to disseminated mineralization
(essentially micro veinlets) pervading through the host rock in irregular pods up to several hundred
feet hi dimension.
Placer deposits are formed when gold-bearing lode ores are exposed to chemical and physical
weathering and subsequent erosion, resulting in transportation and deposition to form sedimentary
deposits. The less-resistant minerals, such as pyrite, are quickly oxidized and leached from the host
rock while gold and other resistant minerals (i.e., silica) persist. Generally, placers are found as
sedimentary deposits associated with stream gravels or beach sand, although some aeolian (windblown
sand) deposits exist. When transported in a stream, gold's high specific gravity causes it to be
deposited in areas where the stream's velocity decreases, settling behind rocks and natural riffles.
The particle size and composition of placer gold deposits usually depend on the distance from the
source and the composition of the original lode deposit. Nugget size decreases downstream because
of the hydraulic gradient. Native gold (60 percent - 90 percent gold) is generally alloyed with silver
and, infrequently, with copper and other metals. These metals are more soluble than gold, and as
they are removed, the gold is concentrated, and the percentage of gold in the nugget or particle is
increased. For this reason, placer deposits farthest from the source tend to be more pure (Park and
MacDiarmid 1975). Over tune, placer gold deposits can be buried and lithified to form fossil placers
Placer gold deposits are discussed in more detail in a separate Technical Resource Document.
Grades range hi all deposit types from subeconomic margins to high-grade cores. High grade vane*
with mining methods but usually refers to ores greater than 0.1 or 0.2 oz/t. Likewise, average
deposit grades are economic distinctions. Deposits requiring high-cost mining and milling method*
may require bulk averages of 0.25 oz/t or more, at 0.15 or higher cutoffs. Those deposits that arc
1-6
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Mining Industry Profile: Gold
amenable to the lowest-cost mining and milling methods may average 0.03 to 0.04 oz/t with an ore-
to-waste separation grade of 0.01 oz/t. Alteration of host rocks surrounding the gold mineralization
affects mining and recovery methods and waste rock characteristics. Various types of alteration are
silicification (replacement of host rock minerals with quartz), decalcification (acid leaching of
carbonate minerals), argillization (replacement by clay minerals), carbonatization (addition of
carbonate minerals), and calcsilicate skanufication (replacement of carbonate minerals by calcium-
silicate minerals).
Gold deposits may be categorized based on similarities in geologic environment and genetic
hydrothermal factors. Recent data show that the 25 largest gold producing mines may be grouped
into four types: sediment-hosted disseminated gold (SHDG), volcanic-hosted epithermal deposits,
porphyry copper-related deposits, and greenstone gold-quartz vein deposits (U.S. DOI, Bureau of
Mines 1990c).
1.3.1 Types of Gold Ore Deposits
1.3.1.1 Sediment-Hosted Disseminated Gold
These deposits are hosted by silty-sandy carbonate sediments. Epithermal hydrothermal systems alter
and deposit gold in the sediments. Alteration decalcifies, argillizes, or silicifies the sediments. Gold
mineralization is associated with the introduction of sulfide minerals and petroleum-based organic
carbon. Sulfide contents typically range from trace to 5 percent. Gold is typically disseminated
throughout the altered sediments. The largest mines of this type are the Goldstrike Mine and the
Gold Quarry Mine of the Carlin Trend.
1.3.1.2 Volcanic-Hosted Epithermal Deposits
These deposits are found in intrusive/volcanic complexes and are formed by.epithermal hydrothermal
systems directly associated with cooling intrusive or volcanic rocks. Wall rock alteration may be
minor to strong silicification and argillization. Sulfide contents range from 1 to 15 percent. There is
a broad range of deposit morphologies from distinct, large veins to stockwork disseminations.
Likewise, there are distinct and broad chemical/mineralogic variations. Typical subgroups are Au-Te
vein deposits (Telluride, Colorado), base metal/carbonate vein deposits (Creede, Colorado), Au-Ag/
quartz-adularia vein deposits (Tonopay, Nevada), Au quartz-alunite vein deposits (Goldfield, Nevada),
and Au-Ag Hot Springs deposits (McLaughlin, California).
1.3.1.3 Porphyry Copper-Related Deposits
Porphyry copper deposits are formed from hydrothermal systems developed and zoned around
discrete intrusive granite stocks at depths of 2 to 2.5 km. The stocks may intrude both sediment or
volcanic rocks and form deposits. Wall rock alteration is zoned around the stock and variable,
depending on host rocks. Sulfide minerals, primarily pyritc. copper-sulfides, and molybdenum
1-7
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Mining Industry Profile: Gold
sulfides, are zoned in proportions of 1 to 15 percent around the stock. Many porphyry copper
deposits contain low grades of (less than 0.01 oz/t) gold but produce significant gold as a byproduct
of the large tonnages mined for the copper (Bingham Canyon, Utah).
Associated with porphyry hydrothermal systems hosted by sedimentary rocks are skarn deposits.
Skarns are formed where the porphyry hydrothermal system interacts with limestone sediments, the
result being complete calc-silicate skarn alteration of the limestone. Iron and base metal sulfide
content often approaches 50 percent. Some skarns are sufficiently gold-enriched to be mined as
primary gold deposits (Fortitude, Nevada).
1.3.1.4 Greenstone Gold Quartz Vein Deposits
Very generally grouped, these deposits are distinct veins in Greenschist facies metamorphosed deep
sea sediments. The veins are mesothermal deposits generally formed during metamorphism.
Carbonate alteration invades the wall rocks around the veins. Sulfide contents are typically nil in the
veins and wall rocks. Only two deposits in the United States fall into this category, but their gold
production is significant. The Homestake Mine, South Dakota, is a deposit hosted in an Archean iron
formation. Gold is associated with quartz veinlets distributed through distinct horizons in the iron
formation. The Mother lode vein system in California is distinct gold-quartz veins in Mesozoic
argillites (Jamestown, California). Erosion of these veins produced the rich placer deposits of
California.
1.3.2 Mineral Content
The mineral content or assemblage of a deposit is the result of reactions between hydrothermal
solutions and the wall rock, influenced by wall rock chemistry, solution chemistry, temperature, and
pressure. Most gold ores contain some amount of sulfur-bearing minerals; carbonate deposits may.
also contain carbonaceous material. The weathering environment affecting the ore body following
deposition is determined mainly by the location of the water table in relation to the deposit. Ores
above the water table, in the vadose or unsaturated zone, will tend to be oxidized (referred to as
"oxide ores"), while ores below the water table will usually be unoxidized (referred to as "sulfide
ores").
Gold ores may contain varying amounts of arsenic, antimony, mercury, thallium, sulfur, base metal
sulfides, other precious metals, and sulfosalts. The amount of these constituents depends on the
nature of the deposit and the amount of weathering that has occurred. Subsequent alteration of the
ore by oxidation influences both gold recovery and the byproducts of extracting the ore. Sulfide
minerals oxidize to form either oxides or sulfosalt minerals. Leaching of sulfides or other minerals
may occur in association with oxidation. Sulfide ores retain their original composition. Zones of
secondary enrichment may form at the oxidized/urioxidized interface. A list of elemental constituents
in oxide and sulfide (unoxidized) ores in the Carlin Mine is presented in Table 1-3 (Radtke 1980).
1-8
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Mining Industry Profile: Gold
Table 1-3. Spectrographic Analyses of Samples of Various Types of Unoxidized Ores, Oxidized
and Leached-Oxidized Ores, Carlin Gold Deposit, Lynn Window, Eureka Co., NV
Element
Si(%)>
Al
Fe
Me
Ca
Na
K
Ti
P
Mn (vomY
Ae
As4
Aue
B
Ba
Co
Cr
Cu
Ga
He'
La
Mo
Nb
Ni
Pb
Sb'-«
Sc
Sr
TI
V
W
Y
Yb
Zn'
Zr
:Nonmar
>10.0
5
2
. 5
7
0.05
1.5
0.2
0
100
0
154
9
150
200
7
70
50
15
25
50
15
0
50
15
<40
10
150
70
200
<20
20
2
51
100
Normal1
>10.0
7
2
10
>10.0
0.1
3
0.2
0
150
0
800
12
70
200
5
70
20
15
40
0
7
7
20
0
150
15
0
200
0
<20
30
1.5
114
150
Siliceous'
>10.0
0.5
0.5
0.15
0.03
0.03
0
0.02
0
7
1
385
23
7
500
0
10
70
0
55
0
5
0
3
0
40
0
10
0
70
<20
0
0
6
20
Pyritic*
>10.0
2
3
5
7
0.05
1.5
0.1
0
150
0
180
6
20
100
7
30
30
7
25
50
15
0
70
10
<40
7
100
0
100
<20
15
I
7
100
Carbon-
aceous*
>10.0
3
1.5
10
> 10.0
0.1
1.5
0.1
0
500
2
480
5
100
500
3
70
70
7
20
0
50
0
100
15
60
7
200
0
700
30
70
3
100
70
Arsenical11
>10.0
5
2
7
10
0.07
2
0.15
2
150
0
11.000
69
30
500
3
70
50
10
200
50
10
0
20
0
115
10
150
150
70
20
20
1.5
<5
150
Oxidized*
>10.0
5
2
5
10
0.03
1.5
0.15
0
150
0
1.450
10
70
150
3
50
20
10
35
70
5
0
20
15
129
15
100
50
50
.<20
30
3
163
200
Leached-
oxidized'
>100
5
2
0.5
0.2
0.07
2
0.3
0
10
07
790
50
70
300
1 5
100
30
20
100
50
5
10
15
30
360
15
100
0
200
<20
30
3
65
300
Descriptions correspond to ores from specific locations.
'Elements Si through P given in weight percent.
'Elements Mn through Zr given in parts per million.
'X-ray fluorescence analysis.
(Source: Radtke 1980.)
'Atomic absorption analysis.
'Leico mercury vapor analysis.
Calorimetric analysis.
1-9
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Mining Industry Profile: Gold
The minerals found in gold ores, and elements associated with them, vary with the type of ore.
Sulfide ores contain varying amounts of native gold and silica (SiO^, as well as sulfur-bearing
minerals, including, but not limited to, sphalerite (ZnS), chalcopyrite (CuFeS?), cinnabar (HgS),
galena (PbS), pyrite (F^S), sylvinate ((Au.AgXTez), realgar (AsS), arsenopyrite (FeAsS), ellisite
Cn3AsS3), and other thallium-arsenic antimony-mercury-bearing sulfides and sulfosalt minerals.
Oxide ores may contain varying amounts of these minerals, as well as silica (SiO^, limonite
(FeO-OH-nH2O), calcite (CaCO3), clay minerals, and iron oxides (Hurlbut and Klein 1977).
The mineral assemblage of the ore deposit is an important factor in selecting the beneficiation method.
In general, the percent recovery of gold from sulfide ores using cyanidation is lower and more costly
than for oxide ores. Recovery is reduced because the cyanide solution reacts with other constituents,
such as sulfides in addition to gold, and complicates beneficiation. Increased costs are associated with
the preparation of sulfide ores when they are oxidized in roasters or autoclaves (see the Beneficiation
Section) (Weiss 1985). Milling, flotation, gravity concentration, and other beneficiation methods are
customized to maximize recovery of precious metals from the ore deposit.
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Mining Industry Profile: Gold
1.4 GOLD EXTRACTION AND BENEFICIATION PRACTICES
Gold operations consist of three major steps: extraction, beneficiation, and processing. Extraction is
analogous to mining and is defined as removing ore material from a deposit. Four main techniques
are used in the beneficiation of gold ore: cyanidation, flotation, amalgamation, and gravity
concentration. The method used varies with mining operations and depends on the characteristics of
the ore and economic considerations (U.S. DOI, Bureau of Mines 1984). Figure 1-1 is a diagram of
the common methods used to beneficiate gold. Because lode ore gold mines generally use cyanidation
techniques, the following sections focus on cyanidation. The discussion of amalgamation is brief,
since this method is of historic significance and is not in use today. Gravity concentration methods
are used in placer-type operations and are discussed in a separate Technical Resource Document.
Base metal flotation operations are also discussed in other Technical Resource Documents (See the
Copper and Lead-Zinc Technical Resource Documents). Beneficiation flow sheets for specific mine
operations are presented in Appendix 1-A.
In 1991, cyanidation and direct processing (smelting of precious metals recovered as a by-product
from base metal mining) were used to generate 90 percent and 10 percent of all domestic recovered
lode gold, respectively and 99 percent of all gold produced (Table 1-5, discussed later). Placer
mining accounts for 1 percent of the total gold produced. Amalgamation was used to beneficiate less
than 1 percent of all lode gold in 1986 (1986 was the last year for which complete data were reported
concerning amalgamation) (U.S. DOI, Bureau of Mines 1990a).
1.4.1 Extraction Methods
Gold ore extraction may be conducted using either surface or underground techniques. Mining
methods are selected based on maximum ore recovery, efficiency, economy, and the character of the
ore body (including dip, size, shape, and strength) (Whiteway 1990).
Generally, gold mining is conducted using surface mining techniques in open-pit mines. This is
primarily because of economic factors related to mining large-volume, low-grade ores and the
improvement of cyanide leaching techniques. In 1988, the total of crude ore handled at surface lode
mines was 160 million short tons (97.8 percent), while underground mines accounted for only 3.56
million short tons (2.2 percent) (U.S. DOI, Bureau of Mines 199la). Table 1-4 summarizes the
amount of crude ore, waste, and marketable product generated by surface, underground, and placer
operations in 1988.
About 90 percent of the 201 active gold mines are lode-type and 10 percent are placer (U.S. DOI.
Bureau of Mines 1990a). As noted previously, the top 25 gold-producing mines accounted for 6K
percent of domestic production in 1991.
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Mining Industry Profile: Gold
Placer
Extraction
(Open Pit or Underground)
Base Metal
Flotation
Cyanidatlon
Roasting
Autodavlng &
BiooxUtilort
Coarse Gravity
Carbon In Leach
Carbon to Pulp
I Agglomeration I
Concurrent Tank
Leaching and
Gold Adsorption
on Activated
Carbon
Base Metal
Refining
Gold Adsorption on
Activated Carbon
(Gold Slimes to
Precious Metal
Recovery)
Ekrtton
(stripping
gold from
activated
carbon)
Edition (stripping gold
from activated carbon)
Zinc
Precipitation
Zinc
Precipitation
Etectrowinning
Figure 1-1. Gold Extraction and Beneflciation Overview
1-12
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Mining Industry Profile: Gold
Table 1-4. Crude Ore, Waste, and Marketable Product at Surface
and Underground Gold Mines, 1988
Material/Ratio
Material Handled
Crude Ore
Waste
Marketable Product
Thousand Troy
Ounces
Crude Ore to
Marketable Product
Ratio
Material Handled to
Marketable Product
Ratio
Surf ace (Lode)
Short Tons (OOOs)
553,000
160,000
394,000
5,250
21.3:1
105.4:1
Underground
(Lode)
Short Tons (OOOs)
4,890
3,560
1,340
241
15.7:1
20.3:1
Total Lode
Short Tons (OOOs)
558,000
163,560
395,000
5,490
21.1:1
~»
Placer
Short Tons (OOOs)
32,900
15,000
17,900
153
91.5:1
215.3:1
(Source: U.S. EPA, and compiled from U.S. DOI, Bureau of Mines 1990b.)
Surface mining methods associated with the extraction of gold include open-pit, placer, and dredge
(industry often considers placer and dredge separately). Placer mining is used to mine and
concentrate gold from alluvial sand and gravels. Underground mining operations use various mining
methods, including caving, sloping, and room and pillar. Consolidated ore mining methods include
surface and underground techniques for mining lode ore and are described below. These practices
follow the basic mining cycle of drilling, blasting, and mucking.
1.4.1.1 Surface Mining
The most predominant surface mining method used to extract gold ore is open-pit. Ore containing
valuable minerals usually is surrounded by less valuable material. Overburden, the unconsolidated
soil and consolidated rock material overlying or adjacent to the ore body, is first removed, and the
crude ore is broken and transported to the mill or directly to a heap for beneficiation activities.
Overburden and development rock (sometimes referred to as innerburden if interspersed with the ore
body) may be continually removed during the life of the mine as the pit walls are cut back to permit
deepening of the mine.
The depth to which an ore body is mined depends on the ore grade, nature of the overburden, and the
stripping ratio. The stripping ratio is the amount of overburden that must be removed for each unit
of crude ore mined. Stripping ratios vary wim mine site and the ore being mined. Surface mining of
gold is generally more economical than underground methods, especially in cases when the ore body
1-13
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Mining Industry Profile: Gold
being mined is large and the depth of overburden covering the deposit is limited. An illustration of a
typical surface mine and heap leach operation is presented in Figure 1-2. The primary advantage of
surface mining is the ability to move large amounts of material at a relatively low cost, hi comparison
with underground operations. Open-pit and open-cut mining are considered to be the least expensive
extraction techniques (U.S. EPA, Office of Water, Effluent Guidelines Division 1982).
1.4.1.2 Underground Mining
In general, underground mining involves sinking a shaft or driving a drift near the ore body to be
mined and extending horizontal passages (levels) from the main shaft at various depths to the ore.
Mine development rock is removed, while sinking shafts, adits, drifts, and cross-cuts, to access and
exploit the ore body. From deep mines, broken ore (or muck) is removed from the mine either
through shaft conveyances or chutes and hoisted in skips (elevators). From shallow mines, ore may
be removed by train or conveyor belt. Waste rock, mine development rock, or mill tailings may be
returned to the mine to be used as fill for mined-out areas (U.S. EPA, Office of Water 1982).
1.4.2 Beneficiation Methods
As discussed above, gold beneficiation operations include cyanidation, base-metal flotation, gravity
concentration (for placer deposits), and amalgamation (which is generally no longer used). Base-
metal flotation, gravity concentration, and amalgamation are described only briefly below. Because
most lode ore gold mines use some form of cyanidation, these techniques are the main focus of this
profile. In general, there are two basic types of cyanidation operations, tank leaching and heap
leaching. In addition, tank leaching involves one of two distinct types of operations, Carbon-in-Pulp
or Carbon-in-Leach. In Carbon-in-Pulp operations, the ore pulp is leached in an initial set of tanks
with carbon adsorption occurring in a second set of tanks. In Carbon-in-Leach operations, leaching
and carbon recovery of the gold values occur simultaneously in the same set of tanks. Table 1-5
presents a comparison of gold ore treated and gold product produced by beneficiation method.
1.4.2.1 By-Product Gold (Flotation)
Flotation is a technique in which particles of a single mineral or group of minerals are made to
adhere, by the addition of reagents, preferentially to air bubbles (U.S. EPA, Office of Water 1982).
This technique is chiefly used on base metal ore that is finely disseminated and generally contains
small quantities of gold in association with the base metals. Gold is recovered as a byproduct of the
base metal recovery. Although no production information is available specifically for flotation, U.S.
Bureau of Mines personnel have suggested that production figures presented in Table 1-5 for smelting
may approximate byproduct gold production by the base metal industry. In 1988, smelting recovered
0.67 million troy ounces of gold (11 percent of all domestic gold produced) (U.S. DOI, Bureau of
Mines 1990a).
1-14
-------
Figure 1-2. Typical Surface Mine and Heap Leach Operation
(Source: Martin Litton.)
-------
Mining Industry Profile: Gold
Table 1-5. Comparison of Gold Ore Treated and Gold Product by Beneficiation Method, 1991
--. " - ':'' x
BenefidarJon Method
Cyanidation (All)
Heap Leaching
Tank Leaching
Amalgamation*
Smelting (Ore and Concentrates)11
Total Lode
Placer
Gold Ore Treated
Percent
51
36
14
0.5
49
100
100
Metric Tons
(OOOs)
206,610
145,441
61,168
0.85
201,370
409,018
5.5 million
cubic meters
Gold Product Produced
Percent
90
33
56
0
10
100
100
(1% of total
gold)
Kilograms'
259,163
94,464
161,699
1,048
28,296
286,998
2,888
'Values for amalgamation for 1986 production, the last year complete information has available.
'Smelting of base metal ores and concentrates, mainly copper and lead ores.
cl kilogram is equivalent to 32.1507 troy ounces.
(Source: U.S. DOI, Bureau of Mines 1992.)
Ore is milled and sorted by size in preparation for flotation. The ore is then slurried with chemical
reagents of four main groups: collectors (promoters), frothers, activators, and depressants. In a
typical operation, the ore slurry and reagents are mixed in a conditional cell so the reagents coat the
target mineral. The conditional slurry is pumped to a flotation cell, and air is injected. Air bubbles
adhere to the reagents and carry the target mineral to the surface, away from the remaining gangue.
for collection. In the flotation technique, the target mineral is not necessarily the precious metal or
other value. Depending on the specific gravity and the reagents used, the values may be recovered
from the top or bottom of the flotation cell.
1.4.2.2 Gravity Concentration
Gravity concentration techniques used most at placer mines rely on gravitational forces to suspend and
transport gangue away from the heavier valuable mineral. A separate report discussing this technique
at placer mines is being prepared by EPA.
1.4.2.3 Amalgamation
In amalgamation operations, metallic gold is wetted with mercury to form a solution of gold in
mercury, referred to as an amalgam. This method of beneficiation is most effective on loose or free
coarse gold particles with clean surfaces (U.S. EPA, Office of Water 1982). Because of its high
1-16
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Mining Industry Profile: Gold
surface tension, mercury does not penetrate into small crevices of ore particles as sodium cyanide
does. Consequently, the ore must be milled finely enough to expose the gold material. In 1986, the
lasfyear for which complete statistics were provided, amalgamation operations produced 33,710 troy
ounces of gold (0.5 percent of all gold produced domestically) (U.S. DOI, Bureau of Mines 1990a).
Use of this method of gold beneficiation has been greatly restricted in recent times because of its high
costs, inefficiency in large-scale operations, and scarcity of ores amenable to the technique.
Ore preparation consists of grinding, washing, and/or floating the ore. The ore is then fed into a ball
mill along with mercury to form an amalgam. The amalgam is then passed over a series of copper
plates where it collects. When fully loaded with amalgam, the plate is removed and the amalgam is
scraped off. Upon heating the hardened amalgam in a retort furnace, the mercury is vaporized and
the gold material remains. The mercury driven off by heating is captured, condensed, and reused.
Alternatively, hot dilute nitric acid may be applied to the amalgam, dissolving the mercury and
leaving the gold material. Amalgamation has traditionally been used in conjunction with other
beneficiation methods such as cyanidation, flotation, and gravity concentration (Beard 1987).
Wastes generated as a result of amalgamation activities consist of gangue in the form of coarse- and
fine-grained particles and a liquid mill water component in the form of a slurry. The constituents of
the waste are similar to those found in the ore body (or gravel) plus any mercury lost during
amalgamation. This material is sent to a tailings impoundment (U.S. DOI, Bureau of Mines 1984).
1.4.2.4 Cyanidation
The predominant method used to beneficiate gold ore is cyanidation. This technique uses solutions of
sodium or potassium cyanide as lixiviants (leaching agents) to extract precious metals from the ore.
Cyanide heap leaching is a relatively inexpensive method of beneficiating low-grade gold ores while
tank leaching is used for higher grade ore. In 1988, cyanidation operations (including both heap
leaching and tank operations) treated 146.7 million short tons of gold ore and recovered 5.6 million
troy ounces of gold (U.S. DOI, Bureau of Mines 1990a). This represented 90 percent of all lode
gold produced from all beneficiation methods.
Although other lixiviants are currently being tested, none are known to be used in commercial
operations. Alternative lixiviants include malononitrile, bromine, urea, and copper-catalyzed
thiosulfate (U.S. DOI, Bureau of Mines 1985; U.S. DOI, Bureau of Mines, undated(a)). Bromine,
for example, is being promoted as an alternative to cyanide by the Great Lakes Chemical
Corporation. However, only pilot plant tests are known of at this time (Dadgar 1989; Winegar
1991).
Cyanidation techniques used hi the gold industry today include heap or valley fill leaching followed
by carbon adsorption (carbon-in-column adsorption), agitation leaching followed by carbon-in-pulp
(CEP), or agitated carbon-in-leach (CIL). In situ leaching of gold is being researched by the Bureau
1-17
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Mining Industry Profile: Gold
of Mines, but is not used commercially at this time. Cyanidation is best suited to fine-grain gold in
disseminated deposits. Heap or valley fill leaching is generally used to beneficiate ores containing
less than 0.04 oz/t. CDP and CIL techniques, commonly referred to as tank or vat methods, are
generally used to beneficiate ores containing more than 0.04 oz/t. These gold beneficiation cut-off
values are dependent on many factors, including the price of gold and an operation's ability to
recover the precious metal (van Zyl et al. 1988).
For this discussion, cyanidation-carbon adsorption is considered in four steps: leaching, loading,
elution, and recovery (van Zyl et al. 1988) (see Figure 1-3). In leaching, the cyanide reacts with the
ore to liberate gold material and form a cyanide-gold complex in an aqueous solution. Precious metal
values in solution are loaded onto activated carbon by adsorption. When the loading is complete, the
values are eluted, or desorbed from the carbon, and recovered by electrowinning or zinc precipitation,
prior to smelting.
An alternative to cyanidation/carbon adsorption is cyanidation/zinc precipitation. The cyanidation-
zuic precipitation technique is also presented in four steps: leaching, clarification, deaeration, and
precipitation. The precipitate (a solid) is smelted directly. A full description of activated carbon
adsorption and zinc precipitation follows the discussion of heap leaching. Other methods to separate
the precious metal from the pregnant solution include solvent extraction and direct electrowinning;
these methods are not common in the industry and are not discussed in this profile.
Depending on the type of ore (sulfide or oxide), the gold concentration in the ore, and other factors,
the mine operator may prepare the ore by crushing, grinding and/or oxidation (roasting, autoclaving,
or bio-oxidation) prior to cyanidation or flotation. In some cases, low grade ore is loaded directly
onto heap leach pads with little or no preliminary ore preparation. This practice transports run-of-
mine ore directly to the pad for leaching. In most other cases, the ore is crushed and/or ground,
prior to leaching or flotation. Each of the steps involved in beneficiation is described in detail in the
following sections.
Ore Preparation
Crushing and Grinding
Beneficiation begins with the milling of extracted ore hi preparation for further activities to recover
the gold values. Milling operations are designed to produce uniformly sized particles by crushing,
grinding, and wet or dry classification. Economics play a large part in determining the degree of
grinding or crushing performed to prepare the ore. Other factors include the gold concentration of
the ore, the mineralogy and hardness of the ore, the mill's capacity, and the next planned step in the
beneficiation of the ore. Run-of-mine ores with very low gold concentrations may be sent directly to
a heap leach pile.
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Mining Industry Profile: Gold
tEACHINO
LOADINQ
tLUTIOM
RECOVERY
ORE
CRUSHING
QRINOINQ
BENEFICATION
CALCINATION
ATMOSPHERIC
STRIDING
CONC. SOLUTION
ZINC OUST
CEMENTATION
CLCCTKOWINNINA
LEACHING/SMELTING
DORi BULLION
Figure 1-3. Flowsheet for Recovery of Gold Using Carbon Adsorption
(Source: Van Zyl, et al. 1988.)
1-19
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Mining Industry Profile: Gold
Milling begins when ore material from the mine is reduced in particle size by crushing and grinding.
A primary crusher, such as a jaw type, is used to reduce ore into particles less than 150 millimeters
(about 6 inches) in diameter. Generally, crushing continues using a cone crusher and an internal
sizing screen until the ore is less than 19 mm (3/4 inch). Crushing in jaw and cone crushers is a dry
process, with water spray applied only to control dust. From the cone crusher, ore is fed to the
grinding circuit where milling continues in the presence of water. Water is added to form a slurry
containing 35 to 50 percent solids. Grinding in ball or rod mills further reduces the ore particle size,
as needed. In some cases, ore and water are fed directly into an autogenous mill (where grinding
media are the hard ore itself); or, a semiautogenous mill (where the grinding media are the ore
i t1
supplemented by large steel balls). Between each grinding unit operation, hydrocyclones are used to
classify coarse and fine particles. Coarse particles are returned to the mill for further size reduction.
Milled ore is in the form of a slurry, which is pumped to the next unit operation (Weiss 1985;
Stanford 1987). Fugitive dust generated during crushing and grinding activities is usually collected
by air pollution control device blowdown streams and is generally recirculated into the beneficiation
circuit. Most mills use water sprays to control dust from nulling activities.
Oxidation ofSulfides (Roasting, Autoclaving, and Bio-Oxidation)
After milling, beneficiation of sulfide ores may include oxidation of sulfide minerals and
carbonaceous material by roasting, autoclaving, bio-oxidation, or chlorination.1 Roasting involves
heating sulfide ores in air to convert them to oxide ores. In effect, roasting oxidizes the sulfur in the
ore generating sulfur dioxide that can be captured and converted into sulfuric acid. Roasting
temperatures are dependent on the mineralogy of the ore, but range as high as several hundred
degrees Celsius. Roasting of ores that contain carbonaceous material oxidizes the carbon to prevent
interference with leaching and reduced gold recovery efficiency. Autoclaving (pressure oxidation) is
a relatively new technique that operates at lower temperatures than roasting. Autoclaving uses
pressurized steam to start the reaction and oxygen to oxidize sulfur-bearing minerals. Heat released
from the oxidation of sulfur sustains the reaction. The Getchell and Barrick Goldstrike Mines in
Nevada, the McLaughlin Mine in California, and the Barrick Mercur Mine in Utah are currently
using pressure oxidation (autoclave) technology, totally or in part, to beneficiate sulfide or
carbonaceous gold ores.
Bio-oxidation of sulfide ores employs bacteria to oxidize the sulfur-bearing minerals. This technique
is currently used on an experimental basis at the Congress Gold Property in Canada and at the
Homestake Tonkin Springs property in Nevada. The bacteria used in this technique are naturally
occurring and typically include Thiobadllus ferrooxidans, Thiobacillus thiooxidans, and
Leptospirillumferrooxidans. In this technique, the bacteria are placed in a vat with sulfide gold ore.
The bacteria feed on the sulfide minerals and ferrous iron components of the gold ore. Research is
1 Chlorination is not commonly used to oxidize nil fide ore» because of the high equipment maintenance
costs caused by the corrosive nature of the oxidizing agon
1-20
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Mining Industry Profile: Gold
currently being conducted on other bacteria that can grow at higher temperatures; high-temperature
bacteria are thought to treat the ore at a much faster rate (U.S. DOI, Bureau of Mines 1990a).
Although more time is required for bio-oxidation, it is considered to be less expensive than roasting
or autoclaving (Hackel 1990).
Agglomeration
Ores with a high proportion of small particle size (minus 200 mesh) require preparation before
leaching can be done effectively. Because percolation of the lixiviant may be retarded as a result of
blocked passages by fine-grained particles, these types of ores are agglomerated to increase particle
size. Agglomeration is the technique of aggregating individual particles into a larger mass, thus
enhancing percolation of the lixiviant and extraction efficiency. This technique may, increase the flow
of cyanide solution through the heap by a factor of 6,000, decreasing the overall leaching time
needed. Agglomeration is currently used in half of all heap leaching operations. The agglomeration
technique typically involves (U.S. DOI, Bureau of Mines 1986) the following:
Mixing the crushed ore with portland cement (a binding agent) and/or lime (to provide
alkalinity)
Wetting the ore evenly with cyanide solution to start leaching before the heap is built
Mechanically tumbling the ore mixture so fine particles adhere to the larger particles.
Heap Leaching
In the past 13 years, heap leaching has developed into an efficient way to beneficiate a variety of
low-grade, oxidized gold ores. Compared to conventional cyanidation (i.e., tank agitation leaching).
heap leaching has several advantages, including simplicity of design, lower capital and operating
costs, and shorter startup times. Depending on the local topography, a heap or a valley fill method
may be employed. Where level ground exists, a heap is constructed; in rough terrain, a valley may
be dammed and filled. The design of these leaching facilities and their method of operation are
site-specific and may even vary over time at the same site. Typically, heaps are constructed of
lower-grade oxidized ores. Depending on the type of ore, it may be sent directly to the heap (run-of-
mine ore), crushed, or agglomerated to maximize gold recovery. Recovery rates for heap and valley
fill leaching range from 60 to 80 percent. Prior to constructing a heap, a pad and an impermeable
liner are built to collect the leachate. A diagram of a typical heap leaching system is presented in
Figure 1-4. This method is frequently applied to run-of-mine ore on which minimal or no crushing i>
performed.
Statistics generated by the Bureau of Mines group gold production from heap and dump leaching
together. (Dump leaching is typically conducted on base metal ores from which byproduct gold mi\
1-21
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Mining Industry Profile: Gold
PIT/ORE
SOURCE
SOLUTION
COLLECTION
ORE
^REPARATION
i
SC
APP
, ft t-t
PREGNANTPOND
SOLUTION
HEAP
PAD
pH
CN
WATER
__/
RECOVERY
PLANT
<
1
r
X
BARREN POND
DORE
Figure 1-4. Typical Heap Leaching System
(Source: U.S. DOI, Bureau of Mines 1984.)
1-22
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Mining Industry Profile: Gold
be recovered.) Currently, no gold heap or valley fill leaches are known to operate without a liner
(Hackel 1990). The use of a liner in gold heap leaching operations may prevent the loss of gold
values. In 1988, according to the Bureau of Mines, heap and dump leach operations treated 102.2
million metric tons of gold ore and recovered 2.3 million troy ounces of gold (U.S. DOI, Bureau of
Mines 1990a). This represented 37 percent of all lode gold produced and 42 percent of all gold
produced by cyanidation (see Table 1-5).
Heap leaching activities may involve some or all of the following steps (U.S. DOI, Bureau of Mines
1978, 1984):
Preparation of a pad with an impervious liner on a 1° to 6° slope or greater for drainage,
and extracting ore from the mine site (or alternatively gathering ore from waste piles)
Crushing and/or agglomeration of the ore to between 1/2 and 1 inch in size if necessary
and cost effective; some operations may leach run-of-mine ore (the agglomeration
technique will be discussed later in this section)
Placing the ore on the pad(s) using trucks, bulldozers, conveyor belts, or other equipment
Applying cyanide solution using drip, spray, or pond irrigation (generally between 0.5 and
1.0 pounds of sodium cyanide per ton of solution)
Collecting the solution via ditches, piping, ponds, and/or tanks.
Two common types of pads used in gold heap leaching include permanent heap construction on a pad
from which the leached ore is not removed; and on-off pads, which allow leached ore pile to be
removed following the leach cycle. Permanent heaps are built hi lifts composed of 5- to 30-foot
layers of ore added to the top of the heap. On-off pads are used to a limited extent in the industry
and are constructed to allow spent ore to be removed after the leaching cycle (Lopes and Johnston
1988).
Pad and liner construction methods and materials vary with the type of pad and site conditions.
Construction materials may include compacted soil or clay, asphaltic concrete, and low-permeability
synthetic membranes such as plastic or geomembrane (see Figure 1-5) (van Zyl et al. 1988). Sand or
crushed ore may also be used on top of the synthetic liner to aid in leachate collection and protect the
pad. Older pads tend to be made of compacted clay. Newer pads are usually constructed of synthetic
materials, typically installed over a compacted layer of native soil or imported clay. Some mines use
synthetic liners composed of high-density polyethylene (HOPE) or very low-density polyethylene
(VLDPE) in combination with compacted native materials. These liner systems are referred to as
composite liners. On-off pads are generally constructed of asphaltic concrete to protect the liner from
potential damage by heavy machinery used during unloading. The risk that a liner system will leak is
most acute during mine operation when ore is added to the heap and fluids place pressure on it.
1-23
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Mining Industry Profile: Gold
SINGLE LINERS
CCOMEMIRANC
ClAT
*.'«'.«'.;'.* CONCIETE
ASPHALT
DOUBLE LINERS
ASPHALT
OlAtN
ClAt
(OlOCOMEMtRANC)
TRIPLE LINERS
GCOMEMMANE
CEOMEMMANC
I GEOMEMftRANE
;:£& :£%'?*'&.(*: 0«AIN
% """"
Figure 1-5. Typical On-Off and Life Pad Liner Construction Materials
(Source: Van Zyl, D.J.A., et al. 1988.)
1-24
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Mining Industry Profile: Gold
When all beneficiation ends and the heap or valley fill unit is reclaimed, the operator typically
controls fluid movement to the liner by installing run-on/runoff controls and other measures.
A variation of heap leaching is valley fill leaching (Eurick 1991). This method is used at facilities
with little or no flat land and utilizes liner systems similar to those used in heap leaches for solution
containment. In valley fill leaching, the ore material is placed on top of a liner system located behind
a dam on the valley floor. As in heap leaching, the ore is treated with lixiviant but is contained and
collected internally at the lowest point in the ore on the liner system for further beneficiation, rather
than in an external solution collection pond. Montana, Utah, and other States have approved valley
fill operations.
In these leaching operations, cyanide complexes with gold and other metals as the liquid percolates
through the ore. Because percolation efficiency may be a limiting factor in heap leaching methods,
some operations treat higher-grade ore with cyanide solution during primary crushing. Fine-grained
ore may be agglomerated to increase permeability; this is discussed in the next section. Leaching
typically takes from weeks to several months, depending on the permeability and size of the pile. An
"average/normal" leach cycle takes approximately 3 months (Lopes and Johnston 1988).
The reaction of the solution with the free gold is oxygen-dependent. Therefore, the solution is
oxygenated prior to application or during spraying. The cyanide leachate percolates through the ore
and is collected by pipes located under the pile or carried directly to ditches around the pile (U.S.
DOI, Bureau of Mines 1986; Lopes and Johnston 1988). The solution is then collected in a pond or
tank. The solution pond may be used as a holding pond, a surge pond, or a settling basin to remove
solids contained in the cyanide solution. Some mine operations use an alternative series of ponds,
including one for the barren solution, an intermediate solution pond, and a pregnant solution pond.
The intermediate solution is passed through a new pile for further enrichment to form the final, or
pregnant, solution (U.S. DOI, Bureau of Mines 1984).
These ponds may be single lined but are now more often double lined with plastic (HDPE),
butylrubber, and/or bentonite clay to prevent seepage. To control wildlife access to cyanide solution,
some mining operations have elected to construct tanks to collect and store leachate solutions (as an
alternative to open ponds). For example* the Castle Mountain Project in Barnwell, California, will
collect pregnant solution in three 250,000-gallon sealed tanks (U.S. DOI, Bureau of Land
Management, Needles Resource Area 1990). Those active operations using ponds to store cyanide
solutions may fence or cover the solution ponds with screening or netting in an effort to prevent
wildlife or waterfowl access, respectively.
1-25
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Mining Industry Profile: Gold
Leaching occurs according to the following reactions, with most of the gold dissolving in reaction 2
(van Zyl et al. 1988):
4Au + SNaCN + O2 + 2H2O -* 4NaAu(CN)2 + 4NaOH (Elsener's Equation and
Adamson's 1st Equation)
*
2Au + 4NaCN + O2 4- 2H2O -* 2NaAu(CN)2 + H2O2 + 2NaOH (Adamson's 2nd
Equation)
Leaching is generally effective at a pH of 9.5 to 11, with the optimum being approximately 10.5.
More acidic conditions may result in the loss of cyanide through hydrolysis, reaction with carbon
dioxide, or reaction with hydrogen to form hydrogen cyanide (HCN). Alternatively, more basic
conditions tend to slow the reaction process (U.S. DOI, Bureau of Mines 1984). Typically, the
recovered cyanide solution contains between 1 and 3 ppm of gold material (U.S. DOI, Bureau of
Mines 1986). Irrigation of the heap stops when the pregnant solution falls below 0.005 ounces of
gold per ton of solution (Lopes and Johnston 1988). After the leaching cycle has been completed, the
heap or valley fill unit can be rinsed with mine water or mill waste water to remove most of the
remaining cyanide solution and gold-cyanide complex. Cyanide in the rinse water may be detoxified
using several methods, such as the addition of hydrogen peroxide or sulfur dioxide.
Wastes remaining following the conclusion of heap and valley fill leaching operations include spent
ore hi the piles or spent ore disposed of elsewhere on site in the case of on-off heap leach pads. The
spent ore will contain small quantities of spent cyanide solution, waste water from rinsing the ore,
residual cyanide, and unrecovered gold-cyanide complex.
It is estimated that, in 1980, the gold industry generated 3 million metric tons of heap leach wastes.
This rose to 11 million metric tons in 1982, because of increased use of leaching as a result of rising
gold prices and increased gold production (U.S. EPA 1985). Based on 1988 Bureau of Mines
estimates, 102.3 million metric tons of ore were treated by heap and dump leaching to produce 2.3
million troy ounces (72.7 metric tons) of gold. After leaching is complete, 102.3 million metric tons
of spent ore were or will be generated (less the volume of gold removed). These wastes will be
discussed in the Extraction and Beneficiation Wastes Section.
Recovery of gold from the pregnant solution generated by heap leaching is accomplished using carbon
adsorption or direct precipitation with zinc dust (known as the Merrill-Crowe process). These
techniques may be used separately or in a series with carbon adsorption followed by zinc
precipitation. Both carbon adsorption and zinc precipitation separate the gold-cyanide complex from
the noncomplexed cyanide and other remaining wastes, including water and spent ore.
Unconventional techniques used to recover gold values include solvent extraction, direct
electro winning, and, more recently, ion exchange resin.
1-26
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Mining Industry Profile: Gold
Sources examined for this report disagree as to the relative cost efficiency of each method. Because
of the low cost of zinc, gold concentration by zinc precipitation may cost less than activated carbon
adsorption/electrowinning (U.S. DOI, Bureau of Mines 1986). Activated carbon requires additional
capital expenditures for a stripping plant, electrowinning, and a kiln to reactivate carbon for use in
future beneficiation. On the other hand, carbon adsorption is both more efficient and less expensive,
in terms of capital and operational costs, than zinc precipitation (U.S. DOI, Bureau of Mines 1978).
Activated carbon techniques also are better able to process solutions with low metal concentrations
and are thus most often used on solutions with a gold concentration below 0.05 oz/t of solution (U.S.
DOI, Bureau of Mines 1978, 1984). Carbon-based and zinc precipitation methods are described in
more detail below.
Carbon Adsorption (Carbon-in-Column/Gold Recovery)
In heap leaching carbon adsorption uses the Carbon-in-Column (CIC) technique. In the CIC
technique, the pregnant solution collected from the leach pile is pumped from a collection pond or
tank into a series of cascading columns containing activated carbon. The solution mixes with the
carbon column in one of two methods: fixed-bed or fluid-bed.
The fluid-bed method involves pumping pregnant solution upward through the column at a rate
sufficient to maintain the carbon bed in a fluid state moving gradually down through the column
without allowing the carbon to be carried out of the system. Thus, loaded carbon can be removed
from the bottom of the tank and fresh carbon added at the top. The fluid-bed method is the more
common of the two methods used in operations adsorbing gold-cyanide values from unclarified leach
solutions containing minor amounts of slimes. Because the fluid-bed method uses a countercurrent
operating principal, it is often more efficient and economical than the fixed-bed method hi adsorbing
the gold-cyanide complex from solution (U.S. DOI, Bureau of Mines 1978, 1984).
In the fixed-bed method, the gold-laden cyanide solution is pumped downward through a series of
columns. The columns generally have either flat or dished heads and contain a charcoal retention
screen as well as a support grid on the bottom. Normally, the height-to-diameter ratio of the tanks is
2:1, although, in some instances, a larger ratio will increase the adsorption capacity of the system (see
Figure 1-6) (Weiss 1985).
In each vessel, the gold-cyanide complex is adsorbed onto activated carbon granules that preferentially
adsorb the gold-cyanide complex from the remaining solution as the material flows from one column
to the next. The advantage of the fixed-bed method over the fluid-bed method is that it requires less
carbon to process the same amount of solution (U.S. DOI, Bureau of Mines 1978, 1984). Typically,
the activated carbon collects gold from the cyanide leachate until it contains between 100 and 400
ounces of gold per ton of carbon depending on the individual operation (see Figure 1-7). Loading
efficiency decreases with solutions containing less gold (U.S. DOI, Bureau of Mines 1978).
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Mining Industry Profile: Gold,
Pregnant solution inlet
L+
Completely
loaded
carbon
Hydraulic
discharge
valve
Loaded
carbon
outlet
Partially
loaded
carbon
Unloaded
carbon
Spent solution outlet
Partially stripped
solution
Figure 1-6. Typical Fixed-Bed Multiple Carbon-In-Column Operation
(Source: Society of Mining Engineers, Mineral Processing Handbook 1985.)
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Mining Industry Profile: Gold
375
oz/ton Au
101
oz/ton Au
21
oz/ton Au
Pregnant solution
0.10 oz/ton Au
Recycle
to heap
0.0002 oz Au
2
oz/ton Au
NaCN
CaO
I
Barren
solution
Solution storage
and makeup tank
Figure 1-7. Hypothetical Distribution of Gold in a Continuous Carbon Adsorption Operation
(Source: U.S. DOI, Bureau of Mines 1978.)
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Mining Industry Profile: Gold
The precious metals are then stripped from the carbon by elution. The values can be desorbed from
the carbon using a boiling caustic cyanide stripping solution (1.0 percent NaOH and 0.1 percent
NaCN). Modifications of this method include the addition of alcohol to the stripping solution and/or
stripping under elevated pressure or temperature (40°C to 150°C) (U.S. DOI, Bureau of Mines
1986). At the Barneys Canyon Mine, a stripping solution of hot sodium hydroxide is used. At this
facility, that solution has been tested and shown to be as effective as stripping solutions containing
caustic cyanide (LeHoux and Holden 1990).
After stripping, the carbon is reactivated on or off site and recirculated to the adsorption circuit (U.S.
DOI, Bureau of Mines 1985). This activated carbon is washed with a dilute acid solution (pH of 1 or
2) to dissolve carbonate impurities and metal-cyanide complexes that adhere to the carbon along with
the gold. This technique may be employed either immediately before or after the gold-cyanide
complex is removed (Eurick 1991). Acid washing before the gold is removed enhances gold
recovery. The Barrick Mercur Mine in Utah, the Barrick Goldstrike Mine in Nevada, and the
Ridgeway Gold Mine in South Carolina are examples of facilities using acid prewash techniques,
while the Golden Sunlight.Mine in Montana and the Battle Mountain Mine in Nevada use acid
postwash techniques (see the Mercur Mine flow sheet in Appendix 1-A).
Based on impurities to be removed from the carbon and metallurgical considerations, different acids
and concentrations of those acids may be used. Usually, a hydrochloric acid solution is circulated
through 3.6 metric tons (4 short tons) of carbon for approximately 16 to 20 hours. Nitric acid is also
used in these types of operations, but is thought to be less efficient than hydrochloric acid (HCL) in
removing impurities. The resulting spent acid wash solutions may be neutralized with a high-pH
tailings slurry, dilute sodium hydroxide (NaOH) solution, or water rinse. When the wash solution
reaches a stable pH of 10, it is sent to a tailings impoundment. Metallic elements may also be
precipitated with sodium sulfide (Smolik et al. 1984; Zaburunov 1989).
The carbon is screened to remove fines and thermally reactivated in a rotary kiln at about 730 °C for
20 minutes (Smolik et al. 1984). The reactivated carbon is subsequently rescreened and reintroduced
into the recovery system. Generally, about 10 percent of the carbon is lost during the process
because of particle abrasion. Recirculating the carbon material gradually decreases performance in
subsequent adsorption and reactivation series. Carbon adsorption efficiency is closely monitored and
fresh carbon is added to maintain efficiency at design levels (U.S. DOI, Bureau of Mines 1984,
1986).
The pregnant eluate solution containing gold may undergo electrowinnning or zinc precipitation.
Electrowirming (or electrodeposition) uses stainless or mild steel wool, or copper as a cathode to
collect the gold product. The Golden Sunlight Mine in Montana uses 3.6 kilograms (kg) [8 pounds
(lb.)] of steel wool in eight cathodes within rectangular clectrowinning cells. A 2.5-volt current is
used to 250 amperes per cell during the operation (Smdik et al. 1984). After two cycles of
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Mining Industry Profile: Gold
electrodeposition, the steel wool must be removed and replaced. The depleted stripping solution may
then be reheated and recycled to the carbon stripping system. The steel wool or eiectrowinning
sludge, laden with gold value, is fluxed with sodium nitrate, fluorspar, silica, and/or sodium
carbonate and melted in a crucible furnace for casting into bullion. For gold ores containing
mercury, a retort step is required before gold smelting to recover metallic mercury (U.S. DOI,
Bureau of Mines 1986; Smolik et al. 1984). Zinc precipitation is described below.
Zinc Precipitation (Merrill-Crowe)/Gold Recovery
Although carbon adsorption is the most common method of gold recovery in the United States, zinc
precipitation is the most widely used method for gold ore containing large amounts of silver. Because
of its simple and efficient operation, the Merrill-Crowe process is used at the 10 largest gold
producing mines in the world, all of which are in South Africa. This technique is well suited to new
mines where the ore has a high silver to gold ratio (from 5:1 to 20:1) (van Zyl et al. 1988).
In zinc precipitation operations, the pregnant solution (or the pregnant eluate stripped from the
activated carbon) is filtered using clarifying filters coated with diatomaceous earth to aid in the ,
removal of suspended particles (see Figure 1-8) (Weiss 1985). Dissolved oxygen is then removed
from the solution using vacuum tanks and pumps. This is necessary because the presence of oxygen
hi the solution inhibits recovery (U.S. DOI, Bureau of Mines 1984).
Metallic zinc dust then is combined with the deoxygenated pregnant solution. At some operations, a
small amount of cyanide solution and lead nitrate or lead acetate is added. Lead increases galvanic
activity and makes the reaction proceed at a faster rate. Zinc precipitation proceeds according to the
reaction described below; the result is a gold precipitate (U.S. DOI, Bureau of Mines 1984).
NaAu(CN)2 + 2NaCN +Zn +H2O -* Na2Zn(CN)4 + Au + H + NaOH.
The solution is forced through a filter that removes the gold metal product along with any other
precipitates. Several types of filters may be used, including submerged bag, radial vacuum leaf, or
plate-and-frame. The gold precipitate recovered by filtration is often of sufficiently high quality (45
to 85 percent gold) that it can be dried and smelted in a furnace to make dore (unrefined metals). In
cases where further treatment is necessary, the precipitate may be muffle roasted or acid treated and
calcined with borax and isilica before smelting (Weiss 1985). Following filtration, the barren solution
can be chemically treated (neutralized) or regenerated and returned to the leach circuit (Weiss 1985)
Tank Leaching
In tank leaching operations, primary leaching takes place in a series of tanks, frequently located in
buildings rather than in outdoor heaps or dumps. Finely ground gold ore is slurried with the leaching
solution hi tanks. The resulting gold-cyanide complex is then adsorbed on activated carbon.
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Mining Industry Profile: Gold
NaCN
CaO
or
NaOH
>-
Heap
Barren Solution
Pond
Pregnant Solution
Pond
I Clarification Filter
T
Vacuum
Deaerator
Plate and Frame
Filter
Gold Precipitate
Furnace
Bullion
Pb acetate or
Pb nitrate
Zndust
Figure 1-8. Merrill-Crowe Recovery System
(Source: Van Zyl, et al. 1988.)
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Mining Industry Profile: Gold
in-Pulp (CIP) conducts the leaching and recovery operations in two separate series of tanks, while
Carbon-in-Leaching (CIL) conducts them in a single series. The pregnant carbon then undergoes
elution, followed either by electrowinning or zinc precipitation, as described previously. The
recovery efficiencies found at tank operations are significantly higher than those found at heap leach
facilities. Tank methods recover from 92 to 98 percent of the gold contained in the ore.
Continuous countercurrent decantation (CCD) is a method of washing the solution containing metal
values from the leached ore slurry to produce a clear pregnant solution. This procedure is used for
ores with high silver values that preclude the use of activated carbon and that are very difficult to
filter, thus precluding the use of filters. The resulting pregnant solution is generally treated by the
zinc precipitation technique.
A new technology employed in South Africa uses ion exchange resin hi place of carbon in the CIP
technique. This technologyResin-in-Pulp (RIP)is expected to have lower capital costs and energy
consumption than CIP operations, if they are operated effectively (Australia's Mining Monthly 1991).
If the use of ion exchange resins is found to be compatible with a wide range of ores, the industry
may shift to these resins wherever activated carbon is now used.
The number and size of tanks used in domestic CIP and CIL facilities vary. For example, the
Ridgeway facility in South Carolina uses 10 tanks measuring 52 feet in diameter and 56 feet in
height; the Mercur Mine uses 14 tanks, each of which are 30 feet in diameter and 32 feet in height;
the Golden Sunlight Mine uses 10 tanks, each of which are 40 feet in diameter and 45 feet in height.
Retention tunes vary as well, ranging from 18 to 48 hours, depending on the facility, equipment used,
and ore characteristics (Smolik et al. 1984; Fast 1988; Zaburunov 1989). The amount of gold ore
beneficiated by tank cyanidation methods increased since the mid 1980s.
Ore preparation (including grinding, lixiviant strength, and pulp density adjustment) and the time
required to leach precious metal values varies depending on the type of ore. Oxide ores are typically
beneficiated by grinding to 65 mesh and leaching with 0.05 percent sodium cyanide (for a pulp
density of 50 percent solids) over a 4- to 24-hour period. Sulfide ores are typically beneficiated by
grinding to 325 mesh and leaching with 0.1 percent sodium cyanide for a 10- to 72-hour period (for a
pulp density of 40 percent solids) (Weiss 1985).
Carbon-in-Pulp
[n the CIP technique, a slurry of ore, process water, cyanide, and lime is pumped to the first series of
tanks for agitation and leaching. Gold is leached from the ore in the leach tank train. The slurry
xmtaining leached ore and pregnant solution is pumped to the second series of tanks for recovery. A
liagram of this technique is presented in Figure 1-9.
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Mining Industry Profile: Gold
Ground Ore + NaCN + Lima
Thickened and
Leached Pulp
Loaded
Carbon
Button
J"
Eluate
J
Re-activation
Gold Electrowinning
i
i
i
i
(((*))>
J
U
Tails
Recirculated
Carbon
Screening
Fine
Carbon
\
Gold Melt
Figure 1-9. Typical Carbon-in-Pulp (CIP) Circuit
(Source: Calgon, Granular Carbon for Gold Recovery undated.)
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Mining Industry Profile: Gold
In the second series of CIP tanks, the slurry is introduced into a countercurrent flow with activated
carbon. The slurry enters the first tank in the series containing carbon that is partially loaded with
the gold-cyanide complex (see Figure 1-9) (Calgon Carbon Corporation, undated). In the suspended
slurry, the activated carbon adsorbs gold material on the available exchange sites! As the carbon
material becomes laden with precious metals, the carbon is pumped forward hi the circuit toward the
incoming solids and pregnant solution. Thus, in the last tank, the low-gold percentage solution is
exposed to newly activated and relatively gold-free carbon that is capable of removing almost all of
the remaining precious metals in the solution. Fully loaded carbon is removed at the feed end of the
absorption tank train for elution, followed by electrowinning or zinc precipitation as described
previously. (U.S. DOI, Bureau of Mines 1978, 1986; Stanford 1987).
Carbon-in-Leach
»
The CIL technique differs from CIP in that activated carbon is mixed with the ore pulp in a single
series of agitated leach tanks. Leaching and recovery of values occur in the same series of tanks. A
countercurrent flow is maintained between the ore and the leaching solution and activated carbon (see
Figure 1-10) (Calgon Carbon Corporation, undated). In the first tanks of the series, leaching of the
fresh pulp is the primary activity. In later tanks, adsorption is dominant as fresh carbon is added to
the system countercurrent to the pulp. Adsorption takes place as the gold-cyanide complex mixes
with the carbon. As with Carbon-in-Pulp and heap leach operations, the pregnant carbon undergoes
elution to remove values. The pregnant eluate then undergoes electrowinning or zinc precipitation
prior to smelting.
Tank beneficiation methods produce a waste slurry of spent ore pulp or tailings. Spent ore is pumped
as a slurry to a tailings impoundment (U.S. DOI, Bureau of Mines 1986; Calgon Carbon
Corporation, undated; Stanford 1987). This solution may contain cyanide, spent ore, lost gold-
cyanide complex, gold in solution, and any constituents in the water used in the operation to control
shale. Small amounts of gold will continue to be leached in the tailings impoundment and some gold
may be recovered as this solution is recirculated back to the mill.
Barren leaching solution is either recycled directly back to the beneficiation circuit or sent to a tailings
impoundment depending on the amount of solids in the solution. This solution may contain spent ore,
residual cyanide solution, and minor amounts of gold.
In situ Leaching
In situ leaching, although common in the copper industry, is only an experimental procedure in the
gold industry and is not used in commercial operations. It involves blasting an underground deposit
in place to fracture the ore and make it permeable enough to leach. Subsequently, 20 to 25 percent of
the broken ore is removed from the mine to provide "swell" space for leaching activities. In buried
1-35
-------
ON
Thickened Pulp
Feed, NaCN, &
Ume
Loaded
Carbon
Air
(((*)))
J
0"
«(*»)))
rM*»***M »*<
rAir
F
«()))
J
Carbon stripping column
Reactivation
Kiln
Eluate
if
/\
Electrowinning Cell
Gold Melt
Figure 1-10. Typical Carbon-in-Leach (CIL) Circuit
Granular Carbon for Gold Recovery undated.)
lr
Air
(((«*)))
J
Tails
Recirculated
Carbon
Screening
Fine
Carbon
-------
Mining Industry Profile: Gold
ore bodies, cyanide solution is then injected through a well into the fractured ore zone (see Figure
1-11). At surface ore bodies, the solution can simply be sprayed over the deposit. Recovery wells
are used to collect the gold-cyanide solution after it percolates through the ore. Ground and surface
water concerns, similar to those found with dump leach sites, are commonly cited for in situ
operations. In situ leaching has only been tested at the Ajax Mine near Victor, Colorado (U.S. DOI,
Bureau of Mines 1984).
1-37
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Mining Industry Profile: Gold
Exposed Ore Body
Ore body
Buried Ore Body
Injection wall
Ore body
Solution sprays
Processing plant
Barren solution
makeup tank
Processing plant Barren 8Olutlo.n
, makeup tank
Perforated
casing
+*.-Recovery wall
Pump
Figure 1-11. Typical In Situ Leaching Systems for Exposed and Buried Ore Bodies
(Source: U.S. DOI, Bureau of Mines 1984.)
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Mining Industry Profile: Gold
1.5 WASTES AND OTHER MATERIALS ASSOCIATED WITH GOLD EXTRACTION
AND BENEFICIATION
This section describes several of the wastes and materials that are generated and/or managed at gold
extraction and beneficiation operations and the means by which they are managed. As is noted in the
previous section, a variety of wastes and other materials are generated and managed by gold mining
operations.
Some, such as waste rock and tailings, are generally considered to be wastes and are managed as
such, typically in on-site management units. Even these materials, however, may be used for various
purposes (either on- or off-site) in lieu of disposal. Some quantities of waste rock and tailings, for
example, may be used as construction or foundation materials at times during a mine's life. Many
other materials that are generated and/or used at mine sites may only occasionally or periodically be
managed as wastes. These include mine water removed from underground workings or open pits,
which usually is recirculated for on-site use (e.g., as mill/leaching makeup water) but at times can be
discharged to surface waters. As another example, leaching solutions are typically regenerated and
reused continuously for extended periods. On occasion, however, such as at seasonal or permanent
closure, the solutions are disposed as wastes via land application or other means. Finally, some
materials are not considered wastes at all until a particular time in their life cycles. These include
spent ore at heap leaching operations: here, only when active leaching for precious metals recovery
ends is the spent ore that comprises the heap considered a waste.
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.
Facilities also store and use a variety of chemicals that are required by mine and mill operations. A
list of chemicals used at gold mines, compiled from data collected by the National Institute for
Occupational Safety and Health, is provided in the table below (National Institute for Occupational
Safety and Health, 1990).
The first subsection below describes several of the more important wastes (as defined under RCRA or
otherwise) and nonwastes alike, since either can have important implications for environmental
performance of a facility. The next subsection describes the major types of waste units and mine
structures that are of most environmental concern during and after the active life of an operation.
1-39
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Mining Industry Profile: Gold
Chemicals Used at Gold Mines
Acetic Acid
Acetone
Acetylene
Ammonia
Argon
Asbestos
Butyl Acetate
Calcium Carbonate
Calcium Oxide
Carbon Dioxide
Chlorine
Coal
Copper
Diatomaceous Earth
Dichlorodifluoro-
methane
Diisobutyl Ketone
Ethanol
Fluoride
Graphite
Hexane
Hydrogen Bromide
Hydrogen Chloride
Hydrogen Peroxide
Iron Oxide Fume
Kerosene
Lead
Lead Nitrate
Litharge
Mercuric Chloride
Mercury
Methyl Acetylene-
Propadiene
Mixture
Methyl Alcohol
Methyl Chloroform
Mineral Oil
Molybdenum
Nitric Acid
Nitrogen
Nitrous Oxide
Oxalic Acid
Phosphoric Acid
Portland Cement
Potassium Cyanide
Propane
Pyridine
Silica, Sand
Silica, Crystalline
Silver
Silver Nitrate
Sodium Cyanide
Sodium Hydroxide
Stoddard Solvent
Sucrose
Sulfuric Acid
Tin
Vanadium Pentoxide
Xylene
2-Butanone
Diesel Fuel
No. 1
1.5.1 Extraction and Beneficiation Wastes and Materials
The subsections below describe many of the wastes and materials generated and managed at gold
sites. Notwithstanding the status of a particular waste or material, it should be noted that a number of
factors that determine whether that waste or material poses any risk to human health or the
environment. Perhaps the most important are the inherent nature of the material (which is generally
determined by its origin and the processes by which it is generated), the manner in which the material
is managed, and the environment in which it is managed and to which it could be released. As noted
above, questions concerning the actual status of any particular material or waste should be directed to
the appropriate EPA Region.
1.5.1.1 RCRA Defined Wastes
Waste Rock
According to the 1985 Report to Congress: Wastes From the Extraction and Beneficiation of Metallic
Ores, Phosphate Rock, Asbestos, Overburden from Uranium Mining, and Oil Shale, the greatest
quantity of waste generated as a result of the mining and beneficiation of gold ore is in the form of
overburden and mine development rock. Industry refers to these materials as waste rock. Generally,
these materials are deposited in waste rock piles or dumps. It was estimated that the gold mining
industry generated 25 million metric tons of overburden and mine development rock in 1980 and 39
million metric tons in 1982 (U.S. EPA 1985). Surface mining operations generate more waste per
unit of crude ore extracted than underground operations. At surface mines, 71 percent of all material
handled is discarded as waste. At underground mines. 20 percent of all material handled is discarded.
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Mining Industry Profile: Gold
Using equivalent units, the ratio of material handled to marketable gold produced at lode operations is
682,000:1, the highest among metal ores (U.S. DOI, Bureau of Mines 1991a).
The quantity and composition of waste rock generated at mines vary greatly by site. This material
can contain either oxides or sulfides, depending on the composition of the ore body. Constituents
found in gold ores may include mercury, arsenic, bismuth, antimony, and thallium. These may occur
as oxides, carbonates, and sulfides with varying degrees of solubility. Sulfur-bearing minerals, such
as pyrite and pyrrhotite, can oxidize to form sulfuric acid (U.S. DOI, Bureau of Mines 1984).
Factors that influence acid generation by sulfide wastes include (1) the amount and frequency of
precipitation; (2) the design of the disposal unit; and (3) the acid generation and neutralization
potential of the rock.
Spent Ore from Tank Leaching (Tailings)
Tank leaching, both CIP and CIL circuits, generate spent ore by leaching the gold values from finely
ground ore. The spent ore exits the leach circuit as a slurry composed of gangue and process water
bearing cyanide and cyanide-metal complexes. The characteristics of this waste vary greatly,
depending on the ore, cyanide concentration, and the source of the water (fresh or recycled). The
characteristics of the gangue are dependent on the ore source. The tailings may be treated to
neutralize cyanide prior to disposal. The slurry is typically disposed of in a tailings impoundment
with some of the free liquid component being recirculated to the tank leach as make-up water. In
some cases, tailings may be used to backfill underground workings or used in on- or off-site
construction.
Spent Ore From Heap Leaching
Heap or valley fill leaching generates spent ore when leaching operations cease, usually after the
economically recoverable gold is removed from the ore. Spent ore may contain residual cyanide prior
to initiation of detoxification procedures; some residual cyanide may remain complexed with other
constituents. Spent ore would contain any trace metals present in the ore body. The spent ore in
most heaps is left in place for detoxification and disposal. Ore leached on on-off heap leach pads is
removed after leaching and detoxification and disposed of at an alternative site, such as waste rock or
spent ore disposal sites.
Pads and liners used hi heap leaching operations are considered to be wastes when intended for
disposal, typically at closure of the facility. Depending on the types of liners used in any associated
ponds or collection ditches, some cyanide, cyanide-metal complexes, and gold-cyanide solution may
remain. Ponds and collection ditches may be reclaimed in place by backfilling with fill material; the
pond or ditch liner material may be disposed of in place or removed for detoxification and disposal
elsewhere.
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Mining Industry Profile: Gold
Cyanide Solution
During operation, most of the barren cyanide solution is recycled to leaching activities. However, the
build-up of metal impurities may interfere with the dissolution and precipitation of gold and,
therefore, require a portion of the solution volume to be bled off and disposed of (U.S. EPA, Office
of Water 1982). -Also, barren cyanide solution from both tank and heap leaching must be disposed of
following mine closure (whether seasonal, extended, or permanent closure). In either case, solutions
will contain free cyanide and metallo-cyanide complexes of copper, iron, nickel, and zinc, as well as
other impurities, such as arsenic and antimony, that are mobilized during leaching. Solutions may be
evaporated from ponds, discharged to tailings impoundments, or land-applied (after treatment to
detoxify the cyanide).
Zinc Precipitation Wastes
The wastes from zinc precipitation include a filter cake generated from initial filtering of the pregnant
solution prior to the addition of zinc, and spent leaching solution that is not returned to the leaching
process. The filter cake consists primarily of fine gangue material and may contain gold-cyanide
complex, zinc, free cyanide, and lime. The filter may be washed with water, which is disposed of as
part of the waste. The waste is typically sent to tailings impoundments or piles.
Wastes From Carbon Regeneration
Carbon used in adsorption/desorption can be reactivated numerous times. The regeneration technique
varies with mining operations, but generally involves an acid wash before or after extraction of the
gold-cyanide complex, followed by reactivation-in a kiln. Carbon particles not of optimum size are
either lost to the tailings slurry, or to the greatest extent practicable, captured after reactivation.
Carbon lost to the circuit is replaced with virgin, optimum-size carbon. Wastes from the reactivation
circuits may include carbon fines and the acid wash solution. The carbon may contain small amounts
of residual base metals and cyanide. The acid wash residues may contain metals, cyanide, and the
acid (typically hydrochloric or nitric); according to Newmont Gold Company, the acid is usually
neutralized in a totally enclosed system prior to release. Up to 10 percent of the carbon may be lost
in any given carbon recovery/reactivation circuit from abrasion, ashing, or incidental losses. Most
operations capture less-than-optimum-size carbon particles for recovery of additional gold values
(either on-site or after being sent off-site). Recovery may involve either incineration and subsequent
recovery of the gold that could not be desorbed chemically during the normal course of operations, or
subjecting the material to an extended period of concentrated cyanide leach. Any liquids used to wash
or transport carbon material are generally recirculated.
Amalgamation Wastes
The slurry waste generated by amalgamation is composed of the mercury-bearing solution and
gangue. The characteristics of waste water and gangue from amalgamation vary greatly depending on
1-42
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Mining Industry Profile: Gold
the ore. This waste may be pumped to a tailings pond. Modern placer operations in California have '
recovered mercury from the sediments as a byproduct of historic gold mining. The source of the
mercury is waste from historical amalgamation operations.
1.5.1.2 Materials
Mine Water
Because mine water discharged to the environment can be a source of contamination, it is addressed
in this section although it is not always a RCRA-defined waste. Mine water consists of water that
collects in mine workings, both surface and underground, as a result of inflow from rain or surface
water, and ground water seepage. As discussed previously, mine water may be used and recycled to
the beneficiation circuit, pumped to tailings impoundments for storage prior to recycling or for
disposal, or discharged to surface water under an NPDES permit.
During the life of the mine, if necessary, water is pumped to keep the mine dry and allow access to
the ore body. This water may be pumped from sumps within the mine pit or from interceptor wells.
Interceptor wells are used to withdraw ground water and create a cone of depression in the water
table around the mine, thus dewatering the mine. Surface water contributions to the volume of mine
water are generally controlled using engineering techniques to prevent water from flowing into the
mine, typically by diverting it around pits or underground openings.
The quantity and chemical composition of mine water generated at mines vary by site. The chemistry
of mine water is dependent on the geochemistry of the ore body and surrounding area. After the
mine is closed and pumping stops, the potential exists for mines to fill with water. Water exposed to
sulfur-bearing minerals in an oxidizing environment, such as open pits or underground workings, may
become acidified. In contrast, according to Homestake Mining Company, flooding and subaqueous
deposition of tailings has been used in some unique situations to prevent acidification in mines.
1.5.2 Waste and Materials Management
Wastes and materials that are generated as a result of extraction and beneficiation of gold ore are
managed (treated, stored, or disposed of) in discrete units. For the purposes of this report, waste
units are divided into three groups: (1) waste rock piles or dumps; (2) tailings ponds; and (3) spent
ore piles once the leaching operation ceases in the case of heap leach operations. These units may be
exposed to the environment, presenting the potential for contaminant transport. In addition, mine
structures such as pits and underground workings are described in this section as they may expose
constituents to the environment and increase the potential for transport.
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Mining Industry Profile: Gold
1.5.2.1 RCRA Units
Waste Rock Piles '
Overburden and mine development rock removed from the mine are stored or disposed of in on-site
piles. These piles may also be referred to as mine rock dumps or waste rock dumps. Usually
constructed without liners, these waste dumps are generally unsaturated. Such dumps can generate
acid drainage if sulfide minerals, oxygen, and moisture are present in sufficient concentrations,
without adequate neutralization potential or other controls in the dump itself. As appropriate, topsoil
may be segregated from the overburden and mine development rock and stored for later use in
reclamation and revegetation.
Tailings Impoundments
The disposal of spent ore from tank leaching operations (tailings) requires a permanent site with
adequate capacity for the life of the mine. The method of tailings disposal is largely controlled by the
water content of the tailings. Generally, three types of tailings may be identified based on their water
content: wet (greater than 40 percent of the total weight is water), thickened (approximately 40
percent water), and dry (less than 30 percent water). Tailings impoundments are used to dispose of
the following types of waste:
i " .
Tailings,
Mine water,
Small amounts of activated carbon,
Zinc precipitation wastes,
Barren cyanide solution and cyanide metal complexes, and
Liners and wastes from decommissioned solution ponds, tanks, and collection ditches.
Two general classifications of impounding structures may be used to describe a tailings impoundment:
retention dams and raised embankments. The choice of impounding structure is influenced by the
characteristics of the mill tailings, and area geology and topography. In a few cases, cyanidation
tailings impoundments have been lined with synthetic or clay liners to inhibit seepage of tailings
water.
The size of tailings impoundments varies between operations. For example, the Golden Sunlight
Mine near Whitehall, Montana is planning an expansion; when completed, the total surface area of
the facility's tailings impoundments will be 450 acres with a depth of 150 feet. The impoundment at
the Ridgeway Mine in South Carolina currently measures 210 acres, but was to be expanded to 270
acres when a new pit comes into production. The Pegasus Gold Corporation in Washington,
proposed to use staged construction to build their tailings impoundment embankment. Design
capacity was 49 million tons of tailings (Montana Tunnels Mining, Inc. 1990; Zaburunov 1989).
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Mining Industry Profile: Gold
Spent Ore Piles
Spent ore in heaps that have previously been leached using cyanide (or other lixiviant), and the
associated pads, may contain small amounts of residual cyanide solution and gold-cyanide complexes.
Usually the heap remains in place as a form of spent ore disposal; treatment to neutralize the cyanide
and/or other contaminants, as well as puncturing the liner to allow percolation, may be conducted
prior to abandonment. The spent ore typically contains unleached metals and other minerals
characteristic of the ore body that may present a potential for contaminant transport. During the
design of the heap, it is important to consider that heaps are not only leaching units during active
operations, but also become waste units as the heap is depleted of values.
Spent ore from on-off pads is detoxified, removed, and disposed of in waste rock dumps or spent ore
disposal areas. As discussed in the Ore Characterization Section of this report, the mineralogy varies
widely with the source of the gold ore (U.S. DOI, Bureau of Mines 1984). Spent leach piles are
reported to vary from 2,000 to 1.5 million short tons in size (Versar, Inc. 1985). The Mesquite Mine
in Imperial County, California, uses heaps 75 feet high (20 foot lifts) and covering 92 acres (Silva
1988).
1.5.2.2 Non-RCRA Units
Mine Pits and Underground Workings
*
Pits and underground workings may be allowed to fill with water when a mine closes or stops
operation, since there is no longer a need for dewatering. This accumulated water may acidify
through contact with sulfide minerals in an oxidizing environment resulting in acid generation. The
acid, in turn, may mobilize metals in the remaining rock. In some cases pits and underground
workings are backfilled with waste rock or tailings. The potential for contaminant release is
dependent on site-specific factors.
Abandoned underground mines and mine shafts may be unprotected, and the mine may, with time,
subside, though this is mostly a problem with historical mines. Deficiencies in mine shaft protection
may be caused by the use of unsuitable materials, such as inadequate shaft cappings, or by unexpected
occurrences that break capping seals, such as water surges in flooded mines (U.S. DOI, Bureau of
Mines 1983a).
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Mining Industry Profile: Gold
1.6 ENVIRONMENTAL EFFECTS
Mine pits and underground workings, overburden piles, waste rock dumps, tailings impoundments,
and spent leach piles in the gold industry are potential sources of environmental contamination.
While all are not waste management units, these are areas in which toxic contaminants are commonly
found and have the potential to escape into the environment. Toxicants associated with these areas
may include cyanide, cyanide-metal complexes, heavy metals, and acid rock drainage. These
toxicants may degrade ground water, surface water, soil, and air quality during mine operation and
after mine closure. A discussion of the potential environmental effects associated with gold mining is
presented in the following sections. Specific examples from industry are included in this section, as
appropriate.
This section on environmental effects does not purport to be a comprehensive examination of
environmental effects that can occur or that actually occur at mining operations. Rather, it is a brief
overview of some of the potential problems that can occur under certain conditions. EPA is aware
that many of the potential problems can be, and generally are, substantially mitigated or prevented by
proper engineering practices, environmental controls, and regulatory requirements.
1.6.1 Ground Water/Surface Water
The primary concerns for ground and surface water at mine sites are chemical and physical
contamination associated with mine operation. Acid formed by the oxidation of sulflde minerals may
be a source of long-term problems at facilities that extract and beneficiate sulfide ores. In addition to
wastes, reagents, such as sodium cyanide, used during beneficiation may also be released to ground
and/or surface water. Mine rock dumps, disturbed areas, and haul roads may contribute sediment and
increase the total solids load to surface water bodies. Potential environmental issues related to ground
water are discussed in more detail below.
1.6.1.1 Acid Generation
Acid rock drainage refers to drainage that occurs as a result of the natural oxidation of sulfide
minerals contained hi rock that is exposed to air and water. This phenomenon is often referred to as
acid mine drainage (AMD); however, it is not necessarily confined to mining activities and can occur
wherever sulfide-bearing rock is exposed to air and water. Not all operations that expose sulfide-
bearing rock will generate acid drainage. The potential for acid drainage to occur depends on the
amount and frequency of precipitation, the acid generation and neutralization potential of the rock.
presence of oxygen, and the design of the disposal unit (e.g., encapsulation).
Water percolating through mine workings or piles such as tailings or waste rock may leach sulfidc*
from the ore and surrounding rock and result in the formation of acid drainage. This acid solution
may be discharged to ground or surface water, depending on the hydrology of the site. The acid
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Mining Industry Profile: Gold
generation potential, as well as the potential for release of other constituents, is increased after the
rock is exposed to the atmosphere (i.e., an oxidizing environment). The rate of,acid generation is
also influenced by the presence or absence of bacteria. Bacteria, especially Thiobacillus ferrooxidans,
are able to oxidize sulfur-bearing minerals. The effect of bacteria is pH-dependent; in some cases,
lowering of pH over time produces a favorable environment for specific bacteria, leading to
accelerated acid generation, once the pH reaches the appropriate level.
In rock dumps, overburden piles, and other mine materials piles that are typically unsaturated, acid
drainage may start to form immediately. The acid generation potential, as well as the potential for
release of other constituents, is increased in these units compared to the in-place ore body because the
rock is finely ground or crushed, thus presenting greater particle surface area, and is in an oxidizing
environment. Changes in pH directly affect the availability and transport of metals and other
constituents. In addition, mine dewatering/flooding may result in similar impacts, as discussed in the
following section.
Milled tailings are susceptible to leaching because of the increased surface area exposure of minerals
not extracted during milling. Surface water discharges and seeps from tailings impoundments may
contain elevated concentrations of metals leached from the tailings. Acid drainage from tailings
impoundments may contribute to the leaching and mobility of metals.
1.6.1.2 Mine Dewatering
Surface and underground mines may be dewatered to allow extraction of ore. Dewatering can be
accomplished in two ways: (1) pumping from ground water interceptor wells to lower the water table
and (2) pumping directly from the mine workings. At the end of a mine's active life, pumping
typically is stopped and the pit or underground workings are allowed to fill with water. Over time,
depending on final hydrologic equilibrium, filling may lead to uncontrolled releases of mine water.
The mine water may be acidic and/or contaminated with metals, as well as suspended and dissolved
solids.
1.6.1.3 Release of Cyanide Solution From Active Heap Leach Units
Release of cyanide solutions from active leach piles or leachate collection ponds may occur during
snowmelt, heavy storms, or failures in the pile or pond liners and associated solution transfer
equipment. Although not waste-management related, at some operations, monitoring systems for
cyanide releases may be installed to detect leaks below the pond and hi receiving waters. Monitoring
systems are required by some States; see the discussion in the Current Regulatory and Statutory
Framework Section.
Release incidents were identified by Versar (Versar, Inc. 1985), with most releases being associated
with leachate holding ponds. Doyle (1990) also reported five spill events that occurred during heap
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Mining Industry Profile: Gold
leaching activities in Idaho. Releases of cyanide were caused by heavy snowmelt and ice damage.
Typically, the facility failed to design and monitor a leak detection system and neutralize cyanide
solution prior to winter closure. Although most of these releases were to surface water, cyanide
could also be released to ground water.
At the Summitville Site in Colorado failures in the liner have led to contamination of both surface and
ground water. Discharge from French drains below the heap is contaminated with cyanide. Release
of process water into Wightman Fork of the Alamosa River lead to fish kills in 1986.
At the Kendall Venture mine site in Lewiston, Montana, the ground water beneath the site has
become contaminated with nitrate and cyanide in recent years. Nitrate concentrations in one well
have risen from 0.016 milligrams per* liter (mg/1) in 1988 to 13.6 mg/1 in 1989, exceeding the State
Drinking Water Quality Standard of 10 mg/1. Total cyanide concentrations inside the permit
boundary of the facility have increased from 0.16 mg/1 in 1988 to 0.26 mg/1 in 1989. The State's
"informal" water quality limit of 0.22 mg/1 of free cyanide is set for waters outside the permit
boundary. The permit allows the mine facility to maintain higher levels for the areas addressed by
the permit.
In October 1990, following heavy rains, 10 to 12 million gallons of cyanide solution (100 ppm
cyanide) and several tons of sediment spilled into Little Fork Creek and the Lynches River in South
Carolina from the Brewer Gold Mine. During the same storm, debris blocked a collection channel
and caused a 420,000-gallon spill containing 170 ppm cyanide. The spill resulted in the discoloration
of Little Fork Creek and a fishkill for 49 miles down Lynches River (Doyle 1990; South Carolina
Department of Health and Environmental Control 1990).
In addition to surface and ground water contamination, both cyanide solution collection ponds and.
water in the collection ditches at heap leach operations may contain cyanide and, therefore, may be
potential sources of contamination for birds and other animals that come into contact with the pond.
In response to this, some mine operations are opting to construct tanks for pregnant solutions and
otherwise trying to cover existing ponds with fences, nets, or screens to control access to these water
sources. Other tactics used to repel wildlife include recorded sounds of predator birds, air cannons,
stuffed owls, scarecrows, and firing of hazing shells (Zaburunov 1989). EPA and industry
manufacturers of sodium cyanide have entered into a voluntary testing Consent Order to address
concerns identified by the U.S. Department of the Interior (DOI) Fish and Wildlife Service relating to
wildlife exposure to cyanide.
1.6.1.4 Release From Heap Leach Piles During and After Closure (Reclamation)
When heap leach operations are concluded, a variety of different constituents remains in the wastes.
These include cyanide not removed during rinsing or neutralization, as well as heavy metals, and
sulfides. After the operation has.been closed or reclaimed, runoff from the spent ore may occur
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Mining Industry Profile: Gold
without proper design and construction considerations. This runoff may contain constituents
associated with the ore, such as heavy metals, and total suspended solids. Depending on the method
and completeness of detoxification, spent ore may also continue to have a high pH. Reclaimed piles
may have passive controls to control run-on and runoff; the design capacity of these controls may be
based on the 10-, 25-, or 100-year 24-hour maximum storm event or the probable maximum
precipitation event, depending on the component. The specific requirements are usually determined
by the State.
If sulfide ores are present, they may generate acidic leachate which may mobilize the metals that are
present in the ore. The constituents associated with the leachate (metals and arsenic) can cause
degradation of ground and surface water quality.
1.6.2 Soil
Three types of environmental effects are commonly associated with soils: erosion, sedimentation, and
contamination. Erosion and sedimentation may be caused by land disturbances and removal of
vegetation related to mining activities (situations that are not unique to mining activities). Under
these conditions, precipitation and snowmelt may lead to soil erosion. Soil contamination may result
from solution spills associated with equipment (hydraulic oil), releases of leach solution because liner
or other equipment failure, deposition of contaminated runoff from waste rock piles, or other
circumstances. Included in this section is a review of methods to detoxify cyanide, because spent
solutions are often land-applied as a disposal method.
1.6.2.1 Land Application of Spent Cyanide Solution
Spent cyanide solution is generated as a waste during heap leach operations and closure. Prior to land
application, these solutions may also be neutralized using calcium hypochlorite or ozone, or other
methods (Porath 1981). Cyanide may be degraded or attenuated in soils by volatilization, chelation,
precipitation, adsorption, biodegradation, and oxidation to cyanate. Long-term persistence of cyanide
residues in mining waste are not completely understood (University of California at Berkeley 1988).
1.6.2.2 Detoxification of Cyanide
The probable fate and transport of cyanide in mine wastes were reported as part of the Mining Waste
Regulatory Determination (1986). The rinse solution used to remove residual cyanide and associated
metal complexes from heaps usually consists of fresh or recirculated mine or process water. Rinsing
continues until the effluent contains a predetermined cyanide concentration. Today, current
technology and environmental concerns have led to the development of technologies that attempt to
render cyanide benign in the environment. Many methods exist for complexing or decomposing
cyanide prior to disposal. These are listed below (University of California at Berkeley 1988):
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Mining Industry Profile: Gold
Lagooning or natural degradation through photodecomposition, acidification by CO2 and
subsequent volatilization, oxidation by oxygen, dilution, adsorption on solids, biological
action, precipitation with metals, and leakage into underlying porous sediments.
Oxidation by various oxidants.
Chlorine gas
Sodium and calcium hypochlorites
Electro-oxidation and electrochlorination
Ozone
Hydrogen peroxide
Sulfur dioxide and air.
In all cases, cyanide is oxidized initially to the cyanate, CNO. In some cases the cyanate
ion is oxidized further to NH4+ and HCO3-, and finally the ammonium ion may be
oxidized to nitrogen gas.
Acidification, with volatilization and subsequent adsorption of HCN for reuse.
Adsorption of cyanide complexes on ion exchange resins or activated carbon.
Ion and precipitation flotation through cyanide complexation with base metals and recovery
with special collectors.
Conversion of cyanide to less toxic thiocyanate (CNS~) or ferrocyanide (FeCCN)^4".
Removal of ferrocyanide by oxidation or precipitation with heavy metals.
Biological oxidation.
Each treatment method may generate a different waste with the chemical compounds used in cyanide
removal as constituents. EPA is currently preparing a separate report on cyanide detoxification.
Some of these (e.g., chlorine, ozone, hydrogen peroxide) are toxic to bacteria and other life forms
but are unlikely to persist or can be cleaned up easily. Others (e.g., chloramine or chlorinated
organic compounds) may persist for long periods in the natural environment.
Detoxification of cyanide using hydrogen peroxide is applicable to spent heaps, tailings, and solution
ponds and tanks. The cyanide-bearing solution is sent to a series of hydrogen peroxide reaction
tanks. (Ahsan et al. 1989.) Hydrogen peroxide and lime are added to the solution forming
precipitate of metal hydroxides and oxidizing free and weakly complexed cyanide into cyanate
(QCN-). Additional steps precipitate copper ferrocyanide, a reddish-brown solid that is stable at a r»H
of less than 9. Precipitates are separated from the solution and discharged to the tailings
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Mining Industry Profile: Gold
impoundment. The solution is then recycled until the desired cyanide concentration is attained in the
effluent.
i
INCO has also developed a technique for detoxification of mine waste streams containing cyanide -
such as CIP and CEL pulps, barren solution, pond waters, and heap leach rinse solutions by
removing cyanide and base metal complexes. The INCO process uses SO2 and air, which is
dispersed in the effluent using a well-agitated vessel. Acid produced in the oxidation reaction is
neutralized with lime at a controlled pH of between 8 and 10. The reaction requires soluble copper,
which can be provided in the form of copper sulfate (Devuyst et al. 1990).
States have adopted specific standards for land application of spent cyanide solutions. For example,
South Dakota has set the level for land application of solutions with cyanide at 0.2 mg/1, with
additional requirements for concentrations of other heavy metals, sulfldes, and other constituents, in
conjunction with additional application and monitoring requirements.
EPA is unaware of detailed, long-term field evaluations of the efficiency of any of the cyanide
detoxification methods.
1.6.3 Air
1.6.3.1 Fugitive Dust
The primary sources of air contamination at mine sites are fugitive dust from mine pits and tailings
impoundments. During the active life of the mine, water or chemicals may be applied to these
impoundments to control dust and prevent entrainment. After mine closure, revegetation or other
stabilizing methods may be used to control dust. Air provides exposure routes for constituents
(inhalation, deposition, and subsequent soil or surface water contamination, etc.). The potential
contaminants are heavy metals and other toxics.
1.6.4 Damage Cases
Environmental damages resulting from mining gold and associated minerals have been documented.
Under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA)
(Superfund) and the CWA, EPA has documented contamination to ground water, surface water, air,
and soil media.
1.6.4.1 National Priorities List
EPA has reviewed mining sites on the National Priorities List (NPL). Five sites on the Superfund
NPL have problems related to gold extraction and beneficiation: Carson River, Nevada; Clear
Creek/Central City, Colorado; Cimarron Mining Corporation. New Mexico; Silver Mountain Mine.
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Mining Industry Pro/lie: Gold
Washington; and Whitewood Creek, South Dakota. Appendix 1-B provides a general site description
and a summary of the environmental effects associated with each site.
1.6.4.2 304(1) Sites
Section 304(1) of the Water Quality Act of 1987 requires States to identify water bodies not meeting
applicable water quality criteria, to identify point-source dischargers to these water bodies, and to
develop and require implementation of individual control strategies (ICSs) for those point-source
dischargers that contribute significantly to exceedance to the water quality criteria. Sunnyside Gold
(Mayflower Mill) and Clear Creek/Central City are sites identified under 304(1) as point-source
dischargers of contaminants related to gold mining activities. A summary of each site is provided in
Appendix 1-C. Note that one of these sites, Clear Creek/Central City, is on the NPL and is discussed
in Appendix 1-B as well. ,
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Mining Industry Profile: Gold
1.7 CURRENT REGULATORY AND STATUTORY FRAMEWORK
Gold mining activities are regulated through a complex set of Federal and State regulations. Statutes
administered by EPA, such as the CWA (33 USC §1251 et seq.) and the Clean Air Act (CAA) (42
USC §7401 et seq.), apply to mining sites regardless of where they are located. Operations on
Federal lands are subject to additional regulation by the Federal agency or agencies having
jurisdiction over the lands, such as the Bureau of Land Management (BLM), the Forest Service (FS),
the Fish and Wildlife Service (FWS), and the National Park Service (NFS). In addition, the Army
Corps of Engineers has promulgated rules for construction and mining activities that have a potential
impact on wetlands and navigable waters. Finally, operations must comply with a variety of State
and local requirements, some of which may be more stringent than Federal requirements.
Federal air quality regulations do not specifically address gold mining, but they do regulate sources of
certain types of air pollution. Federal water quality regulations, on the other hand, include effluent
discharge standards for specific types of gold operations. Federal land management agencies have
regulations that, in some cases, target particular types of extraction or beneficiation methods (e.g.,
placer mining turbidity issues). The BLM has a policy for management of mining operations using
cyanide and other leaching techniques. State regulations similarly address operation types (e.g.,
cyanide heap leach operations), but less frequently target specific minerals.
This section summarizes the existing Federal regulations that may apply to gold mining operations. It
also provides an overview of the operational permitting, water quality, air quality, waste management,
reclamation, and wetlands protection regulations in two gold-producing States (Nevada and South
Carolina). The regulatory requirements for heap leach operations in 15 gold-producing States are also
summarized and presented in Table 1-6.
1.7.1 Environmental Protection Agency Regulations
1.7.1.1 Resource Conservation and Recovery Act
The EPA implements the Resource Conservation and Recovery Act (RCRA) to protect human health
and the environment from problems associated with solid and hazardous wastes. Mining wastes are
included in the Act's definition of solid waste. In 1980, RCRA was amended to include what is
known as the Bevill Amendment (§3001(b)(3)(A)). The Bevill Amendment provided a conditional
exclusion from RCRA Subtitle C hazardous waste requirements for wastes from the extraction,
beneficiation, and processing of ores and minerals.
The exemption was conditioned upon EPA's preparation of a report to Congress on the wastes and a
subsequent regulatory determination as to whether regulation under Subtitle C was warranted. EPA
met its statutory obligation with regard to extraction and beneficiation wastes with the 1985 Report to
Congress: Wastes from the Extraction and Beneficiation of Metallic Ores, Phosphate Rock, Asbestos,
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Mining Industry Profile: Gold
Table 1-6. Heap Leach Regulatory Requirements for the 15 Gold-Producing States
' Stak " . '
Alaska
Arizona
California
Colorado
Idaho
Michigan
Montana
Nevada
New Mexico
North Carolina
Oregon
South Carolina
South Dakota
Utah
Washington
- Heap
Leach
Operations
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
No
Regulated
Yesb
Yes
Yes
Yes
Yes
Yes"
Yese
Yes
Yes
Yesd
Yes
Yes
Yes
Yesf
Yes"
Effluent
Standard*
Zero
Discharge
Zero
Zero
Zero
Zero
Zero
Zero
Zero
Zero
Zero
Zero
Zero
Zero
Zero
Zero
Heap
Liner
Yesc
Yes
Yes
Yesc
Yes
No
Yesb
Yes
Yesb
No
Yes
Yes
Yes
Yes
Yes
Residual
Cyanide
Destruction
Yesc
No
Yes
Yesc
Yes
No.
Yes
Yes"
Yes
No
Yes
Yes2
Yes
Yes
No
"AD State discharge standards must meet Federal CWA requirement for zero discharge of process waste water from
cyanidation operations (40 CFR, Pan 440, Subpart J, undated). All States have a 0.22 mg/1 ground water concentration
limit for cyanide.
"Requirement applied on a site-by-site basis.
'Regulated through solid waste regulations.
''State does not have regulations specific to cyanide operations because it does not have such operations. If an application to
conduct a cyanide operation were received, the State would regulate it under general mining regulations with specific
requirements determined on a site-by-site basis.
'1989 State regulations no longer exempt cyanide operations under 5 acres in size.
'State heap leach regulations are being developed.
(Source: Compiled from State regulations.)
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Mining Industry Profile: Gold
Overburden from Uranium Mining, and Oil Shale. In the subsequent regulatory determination (51 FR
24496; July 3, 1986), EPA indicated that extraction and beneficiation wastes (including gold mining
and milling wastes) should not be regulated as hazardous but should be regulated under a Subtitle D
program specific to mining waste.
i
1.7.1.2 Clean Water Act
Under section 402 of the CWA (33 USC §1342), all point-source discharges to waters of the United
States must be permitted under the NPDES with the exception of some storm water discharges
covered by the 1987 amendments to the CWA. A point source is defined as any discrete conveyance,
natural or man-made, including pipes, ditches, and channels. NPDES permits are issued by EPA or
delegated States.
Effluent limits imposed on an NPDES permittee are either technology-based or water-quality-based.
The national technology-based effluent guideline limitations have been established for discharges from
most active gold mines under the Ore Mining and Dressing Point-Source Category 40 CFR Part 44
(40 CFR, Part 440, Subpart J, undated). These regulations address point source discharges from all
types of gold extraction techniques, including open-pit, underground, froth-flotation, heap, in situ,
and tank cyanide leaching. Discharges from regulated operations must meet best available
technology/best practicable technology (BAT/BPT) standards for cadmium, copper, lead, mercury,
zinc, total suspended solids (TSS), and pH. The specific effluent standards for these contaminants are
summarized in Tables l-7a and l-7b. States with heap leach operations typically impose a zero-
discharge requirement for process waste water from cyanide leaching operations. Permit writers can
establish additional technology-based limitations at a specific mine based on best professional
judgment (BPJ).
The permit writer must ensure that the NPDES permit will protect the water quality of the receiving
water. Table 1-8 identifies the Federal water quality criteria established by EPA under the CWA, and
the current drinking water standards, Maximum Contaminant Level (MCL), established by EPA under
the Safe Drinking Water Act (SDWA). The CWA also requires each state to develop water quality
standards to protect the designated uses of receiving waters. NPDES permit writers must also
determine whether technology-based effluent limitations are adequate to ensure that applicable water
quality standards are met. Where technology-based limits are not sufficiently stringent, water-quality-
based effluent limitations must be developed. As a result, an NPDES permit may include technology-
based effluent limitations for some pollutants and water-quality-based effluent limitations for other
pollutants.
Contaminated storm water runoff from some mining operations has been documented as causing water
quality degradation. In the past, storm water discharges received limited emphasis under the NPDES
program. However, EPA promulgated regulations (55 FR 47990; November 16, 1990) that
specifically address point source discharges of storm water from industrial facilities, including active
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Mining Industry Profile: Gold
Table l-7a. BPT1 and BAT2 Standards for the Ore Mining and Dressing Point-Source Category:
Copper, Lead, Zinc, Gold, Silver, and Molybdenum Ore Subcategory
Concentration of Pollutants Discharged hi Mine Drainage (milligrams per liter)
Pollutant
Cadmium
Copper
Lead
Mercury
Zinc
Total Suspended
Solids
PH
BPT Maximum
for! Day
- N/A
0.30
0.6
0.002
1.5
30
6.0 - 9.0
BPT Average of
Daily Values for 30
Consecutive Days
N/A
0.15
0.3
0.001
0.75
20
6.0 - 9.0
BAT
Maximum for
IDay
0.10
0.30
0.6
0.002
1.5
N/A
N/A
BAT Average of
Daily Values for 30
Consecutive Days
0.05
0.15
0.3
0.001
0.75
N/A
N/A
1 BPT - Best Practicable Technology
2 BAT - Best Available Technology
Table l-7b. BPT and BAT Standards for the Ore Mining and Dressing Point Source Category:
Copper, Lead, Zinc, Gold, Silver and Molybdenum Ore Subcategory
Concentration of Pollutants Discharged From Mills That Use the Froth-Flotation
Process Alone or in Conjunction With Other Processes for Beneficiation
(milligrams per liter)
Pollutant
Cadmium
Copper
Lead
Mercury
Zinc
Total Suspended
Solids
PH
BPT Maximum
for 1 Day
0.10
0.30
0.6
0.002
1.0
30
6.0 - 9.0
BPT Average of
Daily Values for 30
Consecutive Days
0.05
0.15
0.3
0.001
0.5
20
6.0 - 9.0
BAT
Maximum for
IDay
0.10
0.30
0.6
0.002
1.0
N/A
N/A
BAT Average of
Daily Values for 30
Consecutive Days
0.05
0.15
0.3
0.001
0.5
N/A
N/A
(Source: 40 CFR Part 440 Subpart J.)
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Table 1-8. Federal Water Quality Criteria and Drinking Water MCL' (mg/1)
ConstitueM
Antimony
Arsenic
Cyanide
Mercury
Thallium
Fresh
Acute"
9,000
190
22
2.4
1,400
Fresh
Chronic1*
1,600
360
5.2
0.012
40
Marine
Acuteb
(-)
36
1.0
2.1
2,130
Marine
Chronic"
(-)
69
, 1.0
0.025
H
Maximum
Contaminant.
Level (MCL)
0.01 or 0.005
(option)0
0.05
0.2
' 0.002
0.002 or 0.001
(option)'
There are no standards for the other metals and minerals (e.g., bismuth, tellurium, pyrite, and pyrrhotite) discussed in the
section on environmental effects.
"Standards are relative to water hardness. Standards shown are for hardness 100.
c(option) Where options are presented, the final limit will depend upon the selection of a Practical Quantitation Limit (PQL),
the limit of detection at which analysis of samples can produce consistent results in normal laboratory conditions.
(Source: U.S. EPA 1991.)
and inactive/abandoned mine sites. These regulations require NPDES permits for all point source
discharges of contaminated storm water from mine sites. Storm water requirements will be applied to
mine sites either individually (i.e., through individual NPDES permits) or in larger groups (i.e.,
through general NPDES permits applicable to similar operations).
Some discharges from mine sites do not meet the traditional definition of a "point-source discharge."
Specifically, runoff from tailings piles, overburden and mine development rock piles, and other mine
areas often is not controlled through a discrete conveyance. As a result, these types of discharges
have frequently been considered nonpoint-source discharges. Under the Section 319 of the CWA.
States have been required to prepare nonpoint-source assessment reports, and to develop programs to
address nonpoint sources on a watershed-by-watershed basis. Each State must report to EPA annual l>
on program implementation and resulting water quality improvements.
1.7.1.3 Clean Air Act
Under the CAA (42 USC § 4209, Section 109), EPA established national primary and secondary
ambient air quality standards for six "criteria" pollutants. These are known as the National Ambictn
Air Quality Standards (NAAQSs). The NAAQSs set maximum concentration limits for lead, niin^cn
oxides, sulfur dioxide, carbon monoxide, suspended paniculate matter of less than 10 microns in
diameter, and ozone. To attain the air quality goals set by the CAA, States and local authorities »crc
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Mining Industry Profile: Gold
given the responsibility of bringing their regions into compliance with NAAQSs. In addition, States
may promulgate more stringent ambient air quality standards. EPA also has promulgated air quality
regulations that specifically address smelting operations. Since this report does not evaluate mineral
processing, no further discussion of those rules are found in this report.
V
New Source Performance Standards, authorized under CAA §111, also have been promulgated for
metallic mineral-processing plants (40 CFR §60(LL)). A processing plant is defined as "any
combination of equipment that produces metallic mineral concentrates from ore; metallic mineral
processing commences with the mining of the ore." However, all underground processing facilities
are exempt from the NSPSs. Also, NSPS paniculate emission concentration standards only apply to
stack emissions. NSPSs require operations to contain stack-emitted paniculate matter in excess of
0.005 grams per dscm. In addition, stack emissions must not exhibit greater than 7 percent opacity,
unless the stack emissions are discharged from an affected facility using a wet scrubbing emission
control device. However, on or after 60 days following the achievement of the maximum production
rate (but no later than 180 days after initial startup), operations must limit all process fugitive
emissions (meaning fugitive dust created during operation though not released through a stack) to 10
percent opacity.
Prevention of Significant Deterioration (PSD) provisions of the CAA are intended to ensure that
NAAQS are not exceeded. Under this program, new sources are subject to extensive study
requirements if they will emit (after controls are applied) specified quantities of certain pollutants.
Few mining sites are subject to PSD requirements since they typically are not predicted to emit
sufficient quantities.
State ambient air standards promulgated to meet or exceed Federal NAAQSs are generally maintained
through permit programs that limit the release of airborne pollutants from industrial and land
disturbing activities. Fugitive dust emissions from mining activities may be regulated through these
permit programs (usually by requiring dust suppression management activities).
4
Currently, only the six criteria pollutants are regulated by NAAQS. Several other pollutants are
regulated under National Emission Standards for Hazardous Air Pollutants (NESHAPs). NESHAPs
address healtn concerns that are considered too localized to be included under the scope of NAAQSs.
Under the 1990 Amendments to the CAA, Congress required EPA to establish technology-based
standards for a variety of hazardous air pollutants, including cyanide compounds. In November of
1993, EPA published a list of source categories and a schedule for setting standards for the selected
sources. Furthermore, if a source emits more than 10 tons per year of a single hazardous air
pollutant or more than 25 tons per year of a combination of hazardous air pollutants, the source is
considered a "major source." Major sources are required to use the maximum available control
technology (i.e., BAT) to control the release of the pollutants (CAA Section 112).
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1.7.2 Department of Interior
1.7.2.1 Bureau of Land Management
Most gold mining operations on Federal lands are conducted on mining claims located pursuant to the
General Mining Laws. Under the 1872 Mining Law, a person has a statutory right to go upon the
open (unappropriated and unreserved) public lands of the United States for the purpose of prospecting
for, exploring, developing, and extracting minerals. Once a person has made a valuable mineral
discovery and has properly located the claim pursuant to the mining laws, the person has broad
possessory rights to develop the minerals upon which the claim was based.
Because of the broad nature of the claimant's possessory rights, the Federal agencies having
management responsibilities over the lands upon which the claim is located cannot, in most cases,
wholly restrict mining operations. Nonetheless, the surface managing agency can subject the mining
operations to reasonable regulation to prevent "unnecessary and undue degradation" of Federal lands.
All mining claims located on lands managed by the BLM are subject to BLM regulation to prevent
"unnecessary and undue degradation" of the Federal lands and resources involved. The BLM's
authority to regulate mining claim operations under this regulation derives from the Federal Land
Policy and Management Act of 1976 (FLPMA), the statute which sets out the BLM's general land
management and planning authority. Exploration sites are subject to the less-than-5-acre exemption or
must submit a plan of operation if greater than 5 acres.
The BLM's general surface management regulations governing mining claim operations, which
include gold mining operations, are found at 43 CFR Part 3809. These regulations cover general
design, operating and reclamation standards, monitoring requirements, bonding requirements,
environmental review requirements, and remedies for noncompliance. They establish three general
use categories for mining operations, each eliciting different levels of oversight by the BLM. These
categories are (1) casual use operations (i.e., those that normally result in only negligible disturbances
of Federal lands and resources and that require no prior notice to or approval from the BLM), (2)
notice-level operations (i.e., those that involve disturbances of 5 acres or less for which the operator
must notify the BLM prior to commencing surface disturbing activities), and (3) plan-level operations
(i.e., disturbances of greater than 5 acres, and operations in some specified areas, for which the
operator must obtain BLM approval of a plan of operations prior to commencing activity).
All operations, including casual use and operations under either a notice or a plan of operations, must
be conducted to prevent unnecessary or undue degradation of the Federal lands. All operations must
also be reclaimed and must comply with all applicable State and Federal laws, including air and water
quality standards such as those established under the CAA and the CWA.
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All mining operations are subject to monitoring by the BLM to ensure that they do not cause
unnecessary or undue degradation, and that all operators are responsible for fully reclaiming the area
of their claim.
The current BLM policy for bonding was established by an internal Instruction Memorandum (IM)
issued on August 14, 1990 (U.S. DOI, Bureau of Land Management 1990a). Under this IM, the
BLM will not require bonds for most casual use or notice-level operations. However, a 100 percent
reclamation bond will be required from all operators who have established records of noncompliance.
Additionally, the IM requires the posting of a 100 percent reclamation bond for all operations that use
cyanide or other leachates and discharge cyanide-bearing tailings or fluids to impoundments or tailings
ponds. The 100 percent bonding requirement applies only to those portions of the operation
encumbered by cyanide facilities.
All plan-level operations, regardless of operation type (e.g., strip, open-pit, dredge, and placer) will
be required to post a bond. Bond amounts are to be set at the discretion of the BLM (up to $2,000
per acre, except as noted above), depending on the nature of the operation, the record of compliance,
and whether it is covered by a satisfactory State bond.
By another internal IM issued on August 6, 1990 (U.S. DOI, Bureau of Land Management 1990a),
the BLM established uniform standards for surface management of mining operations that use cyanide
and other chemical leaching methods for mineral extraction on public lands. This IM directs BLM
Area and District offices to inspect all cyanide operations at least four times a year. All facilities
employing cyanide leaching techniques must be fenced and must ensure protection of the public,
wildlife (including migratory birds), and livestock. All operations must use the Best Practicable
Technology (BPT) and must meet at least the following standards:
Facilities must be designed to contain the maximum operating water balance in addition to
the water from 100-year, 24-hour storm event. Containment ponds must be included in all
containment systems.
Tanks containing lethal solutions must be bermed to contain the maximum tank contents in
the event of catastrophic tank failure.
Facilities must be constructed so that solution containment is maximized.
Leakage detection and recovery systems must be designed for heap and solution
containment structures. Monitoring of ground and surface water through closure and final
reclamation is required.
Cyanide solution and heaps must be neutralized or detoxified.
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Mining Industry Profile: Gold
Surface disturbances must be minimized.
Engineering designs, maps, and cross sections of the leaching facilities must be submitted
1 as part of operating plans. Ground water and soil mechanics information is required for
review of the designs.
These minimum standards must be met by all operations under mining claims on BLM land that use
cyanide leaching techniques, unless an equally effective standard is set and enforced under State law.
The authorized officer may waive certain of these minimum standards for existing operations in
limited circumstances and only when the operations are not resulting in unnecessary or undue
degradation or causing other unacceptable results (such as unauthorized discharges or avian
mortalities). The BLM will supplement these minimum criteria through the development of State
and/or district or resource area plans, as appropriate.
Mining claims located in BLM wilderness study areas are generally subject to stricter regulation than
other mining claims. The regulations covering mining in wilderness study areas are found at 43 CFR
Part 3802. The IM discussed above for cyanide management applies to relevant operations in
wilderness study areas in addition to the 43 CFR Part 3809 regulations.
The BLM has the authority to issue leases for gold on certain acquired (as opposed to public domain)
lands. Although this is rarely done, such leases would be covered by the general regulations
applicable to hardrock leasing found at 43 CFR Part 3500.
1.7.2.2 National Park Service and Fish and Wildlife Service
Generally, location of new mining claims is prohibited in most areas managed by the NPS and the
FWS. Regulations at 36 CFR Part 9 govern activities on land managed by the NPS under patented
and unpatented mining claims already in existence prior to the time the lands were included with units
of the NPS. On the, other hand, the regulations at 50 CFR Part 29 govern mining activities under
mineral rights on lands managed by the FWS that were vested prior to the acquisition of the land by
the United States. As of 1989, mining activities were being conducted in 14 refuges under the
jurisdiction of the FWS, 8 of which were in Alaska (Kilcullen 1990).
1.73 Department of Agriculture; Forest Service
Although the BLM has general management authority for the mineral resources on FS lands, the
BLM regulations governing activities under mining claims do not apply to units of the FS. Instead,
surface uses associated with operations under mining claims on FS lands are governed by the FS
regulations hi 36 CFR Part 228, Subpart A. The FS regulations generally mandate that operations
under mining claims be conducted to minimize advene environmental impacts on FS surface
resources.
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Mining Industry Profile: Gold
The FS regulations are similar to the BLM regulations and provide for FS consultation with
appropriate agencies of the U.S. DOI in reviewing technical aspects of proposed plans of operation.
However, the FS regulations differ in that the general use categories do not specify acreage, as
opposed to the BLM's, where the use category is based on the acreage disturbed. The FS regulations
require that persons proposing to initiate any operations that might disturb surface resources must file
a notice of intent to operate with the district ranger with jurisdiction over the area to be affected. If
the district ranger determines that the operations will be likely to cause significant disturbance of
surface resources, the operator must submit a proposed plan of operations. Neither a notice of intent
to operate nor a proposed plan of operations are required for the locating or marking of mining
claims; mineral prospecting or sampling that will not cause significant surface disturbance; operations
that do not involve the use of mechanized equipment or the cutting of trees; or uses that will be
confined to existing roads.
/
The proposed plan of operations must include a thorough description of the proposed site, the nature
of the proposed operations, and measures for meeting environmental protection requirements.
Operations must comply with applicable environmental laws and must, where feasible, minimize
adverse environmental effects on FS resources. The FS will conduct an environmental assessment of
the proposed plan of operations and, if necessary, prepare a National Environmental Policy Act
(NEPA) environmental impact statement.
The regulations specify standards for reclamation and provide that the district ranger may require a
reclamation bond to cover the cost of reclamation. Where State bonding regulations exist, the FS has
established memorandums of understanding with the States to prevent double bonding. In these cases,
the bond amount must meet the more stringent standard, whether it is that of the State or the FS.
Regulations specific to mining operations on FS Wilderness Areas are found at 36 CFR Part 293.
1.7.4 Army Corps of Engineers
Gold mining operations that fall within the jurisdiction of Army Corps of Engineers include placer
mines, which have a great potential to physically restructure wetlands or "navigable waters." Until
1986, most placer mining activities were regulated by the Corps, under Section 404 of the CWA,
through permits for the discharge of dredged materials. In 1986, the Corps and EPA entered into an
agreement (updated in 1990) on the definition of "fill material" for 404 permitting. The agreement
provided that jurisdiction of placer mining discharges would be determined on a case-by-case basis.
Since then, the Corps has been responsible only for dredge and fill activities accessory to mining
operations. These activities include construction of sediment ponds and roads, filling of dredge pits,
etc., and are regulated nationwide through permits issued by the Corps.
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Mining Industry Profile: Gold
1.7.5 STATE REGULATIONS
1.7.5.1 Nevada
Nevada has regulatory requirements controlling gold mining activities. Some of the regulations are a
result of Federal program delegation (e.g., NPDES), while others were developed under Nevada
statutes (e.g., reclamation).
In Nevada, 80 to 90 percent of mining operations are located on BLM or FS land. According to a
State official, Nevada considers the Federal Government's role as a land owner to be no different
from the role of any other land owner (Taff 1991). Although Federal agencies like the BLM and FS
have the authority to manage the resources on their land, the State does not believe they have the
authority to supersede State regulations designed to protect the environment as a whole. Nevada
considers its regulation of mining, including operational permitting and reclamation requirements, to
be part of its efforts to protect general environmental quality, especially water quality. Therefore,
operations located on Federal lands must comply not only with the BLM or FS operating and
reclamation requirements, but also with State operating and reclamation permitting requirements and
general air and water quality regulations.
More specifically, an operation on Federal land must obtain both an operating permit from the State
and "notice" or "plan of operations" approval from the appropriate Federal agency (see the BLM and
FS discussion above for specifics regarding when "notice" and "plan of operations" are required).
Similarly, operations located on Federal land must obtain State "reclamation permits" (separate from
operating permits), and must also comply with BLM/FS reclamation requirements. However, specific
attention has been given to facilitate compliance with both State regulations and the BLM and FS
regulations. For instance, State permits incorporate most of the BLM and FS requirements. For this
reason, and because State pennit requirements are more comprehensive than those promulgated by the
BLM and FS, a State pennit is considered by the BLM and FS to be adequate proof that all their own
requirements have been met (Taff 1991). However, the appropriate Federal agency performs
comprehensive analysis, the results of which are incorporated into the permit. The specific State
regulations governing gold mining operations are discussed below.
Reclamation
Although the State's operating permits contain some reclamation requirements (such as the
stabilization of tailings and closure planning), reclamation permits address, in greater detail, the
specific closure procedures the operator agrees to undertake. Specific requirements are applied on a
case-by-case basis but generally include revegetation and containment of all wastes to prevent runoff
and erosion. Both operating permits and reclamation permits require facilities to submit closure plans
for process component sources (denned as any distinct portion of a facility that is a point .source) at
least 2 years before the anticipated closure of the source (Nevada Administrative Code 1989).
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Mining Industry Profile: Gold
Reclamation regulations that became effective on October 1, 1990, require all existing exploration
projects and mining operations to obtain a reclamation permit no later than whichever is earlier:
October 1, 1993, or abandonment of the project. All new exploration projects and mining operations
must obtain a permit prior to beginning operations. Each reclamation plan must identify a proposed
postmining land use for the area that will be disturbed by operations and must describe the manner in
which the disturbed area will be reclaimed to a condition that will support the proposed postmining
land use.
In addition, each reclamation permit must be supported by a reclamation surety. The regulations
identify several forms of surety that are acceptable. The amount of the reclamation surety is
determined by estimating the actual cost to the Government agency of implementing the proposed
reclamation plan.
Nevada regulations now require all surface mines to purchase reclamation bonds. Existing mines,
however, had until 1993 to purchase bonds. Under a memorandum of understanding between the
State, the FS, and the BLM, mining operations in the State on Federal land may have either the State,
the BLM, or the FS designated as the holder of the reclamation surety. This prevents double bonding
on Federal lands. However, when operations have the BLM or FS as the surety holder, the State
retains the right to evaluate the surety amount for adequacy and may require additional surety if it is
found to be insufficient to ensure reclamation. The State calculates the bond amount based upon the
potential estimated cost to the agency of reclaiming the site if the operator fails to complete
reclamation and based on the operator's record of compliance (Taff 1991).
Water Quality
Nevada regulates the discharge of pollutants, including suspended solids, from mining activities under
a federally approved NPDES program. The State program requires pollution control permits for heap
leach operations and mill dischargers (Miereau 1991). Pollution control permits prohibit the
discharge of process fluids or liquid waste streams from these facilities during operation and closure
activities. To obtain a pollution control permit, a facility must incorporate Best Management .
Practices (BMPs), including double-lined ponds or clay-lined tailings impoundments, into its design.
Also, the placement of waste rock and tailings must be such that the potential for leaching is
minimized. The State did approve a "319" Nonpoint-Source Pollution Management Program. It has
drafted BMPs, but no regulations.
In addition, Nevada allocates water rights by establishing preferred uses of water within designated
ground water basins. Mining is considered a preferred use for certain ground water basins.
However, to access water reserves, mining operations must obtain a special appropriation permit to
withdraw a certain amount of ground water or surface water from a particular basin. The State limits
total withdrawals from any given basin to the annual recharge or "perennial yield" of the basin
(Jessup 1988).
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Mining Industry Profile: Gold
As of September 1, 1989,, all existing mining facilities were given 3 years from that date to obtain
operating permits (Nevada Administrative Code 1989). After July 1, 1990, all new onsite
/
construction or modification projects were required to obtain permits. Permit applications require a
plan of operations, hydrogeologic studies, assessment of impact to surface and ground water, methods
for the control of storm water, notification of disposal sites for spent ore, etc. However, pilot
facilities, small-scale operations (less than 10,000 tons of ore chemically processed per year or no
more than 30,000 tons total per mine lifetime), and placer operations that rely exclusively on physical
separation methods may file an abbreviated permit application. Permits also require stabilization of
tailings and spent ore. Tailings and impoundment materials must be sampled and characterized once
the impoundment is no longer active. In addition, mining operations are required to leave tailings
impoundments in a state that is not hazardous to wildlife. Spent ore from cyanide leaching methods
must be rinsed until weak acid dissociable (WAD) cyanide levels in the effluent rinse water are less
than 0.2 mg/1, the pH of the effluent rinse water is between 6 and 9, and any runoff from spent ores
piles would not degrade the waters of the State.
As part of the Water Pollution Control Permit, mines report quarterly on results of meteoric water
mobility testing and waste rock analysis to determine the acid-generating potential of waste rock. The
meteoric mobility test is an extraction procedure. The extracted solution is analyzed for nitrate,
phosphorous, chloride, fluoride, total dissolved solids, alkalinity, sulfate, and metals. Waste rock
analysis is intended to determine the net acid generation potential of the material placed in the waste
rock dump during a quarter. Samples are collected daily during the quarter and classified based on
their net carbonate value as sulfate: highly basic, basic, slightly basic, neutral, slightly acidic, acidic,
and highly acidic. The quarterly composite sample to be analyzed is prepared on a tonnage weighted
average for each classification and aggregated prior to analysis.
Air Quality
Nevada's ambient air quality standards meet, but do not exceed, Federal requirements, with the
exception of the ambient standards for the Lake Tahoe area. For this area, the State has promulgated
standards for ozone and carbon monoxide that are tougher than those required by EPA (Jessup 1988).
Air quality permits must be obtained for the construction and operation of any new sources. An
evaluation must be submitted by the applicant prior to the issuance of a registration certificate for a
new or modified point source. This evaluation must include an estimate of air quality after
construction of the proposed facility to ensure that ambient air quality will be maintained. In
addition, Nevada's air quality regulations contain emission limits for specific mining companies,
including several precious metal mining operations. Under Nevada Administrative Code (445.430-
445.846), Point-Source Paniculate Permits are required. These permits cover fugitive dust from
construction and operation activities.
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Mining Industry Profile: Gold
1.7.5.2 South Carolina
South Carolina has regulatory programs, including permitting and bonding, that control gold mining
activities. Some programs are delegated by the Federal government while others are under the
authority of South Carolina statutes.
Operating Permits
Under the South Carolina Mining Act (Section 48-20 of the State Code), the Division of Mining and
Reclamation of the Land Resources Commission (LRC) is charged with ensuring that lands and waters
involved in mining are protected and restored to the "greatest practical degree." LRC's
responsibilities include issuing mining and reclamation permits, reviewing and approving reclamation
plans, collecting reclamation bonds, and inspecting facilities to ensure compliance. LRC coordinates
its activities with and supplements the regulatory activities of the Department of Health and
Environmental Control (DHEC). As amended in 1990, the Act states clearly that reclamation
requirements for a mine facility are part of closure. Annual reclamation reports are required by LRC
and are also required through construction permits issued by DHEC. The South Carolina Mining
Act, as amended in 1990, gives the LRC authority to assess civil penalties for noncompliance with the
approved reclamation plan or schedule of reclamation. Penalties up to $1,000 per day per violation
are authorized.
Operating permits are required for all surface mining activities with excavations exceeding 1 acre in
area (South Carolina Code of Regulations 1980). Permits require submittal of site location and
hydrogeologic information, facility construction plans, and containment system plans (e.g., settlement
ponds and terraces). Reclamation plans are also required with any operating permit application.
Reclamation is not required where infeasible for particular areas, provided steps are taken to minimize
the extent of the disturbance.
Reclamation
Reclamation bond amounts are set at the discretion of the DHEC. To obtain bond release, mining
sites must be revegetated, slopes must be graded, and a useful purpose established for any water
impoundments.
Water Quality
South Carolina's Bureau of Water Pollution Control (WPC) within DHEC is charged with protecting
surface and ground waters of the State. The Bureau's authority stems from the Clean Water Act
(CWA) and the South Carolina Pollution Control Act (PCA). Applicable regulations include: SC
Regulation 61-9 (NPDES Permits), SC Regulation 61-68 (Preparation and Submission of Engineering
Reports), SC Regulation 61-68, -69 (Water Classification and Standards), and SC Regulation 61-71
(Well Standards and Regulations).
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Mining Industry Profile: Gold
The Bureau's authority over mining facilities extends as long as there are potential impacts to
surrounding waters, from construction through post-closure. The Bureau's program is implemented
through permitting systems, violation of which can result in the issuance of consent orders or
administrative orders as well as civil and criminal actions. The Bureau issues NPDES permits for
surface water discharges, as well as construction permits for facility components, which include
ground-water monitoring requirements.
South Carolina has an EPA-approved NPDES program and regulates effluent discharges accordingly.
The State discharge limits are the same as the Federal guidelines. In addition to classifying surface
waters according to expected use, the State has ground water classifications that are intended to
maintain ground water quality. The State classifies all ground water as "Groundwater B" (GB),
meaning that it must be suitable for use as drinking water without pretreatment. State drinking water
MCLs are the same as Federal MCLs. Two other classifications, one more stringent [Groundwater A
(GA)] and one less stringent [Groundwater C (GC)], can be applied only upon petition by a private
interest (Jessup 1988). However, the State official contacted knew of no instances where GA or GC
classifications had been granted (Kennedy 1991). Mining operations are required to install monitoring
wells to ensure that ground water quality standards are maintained.
To further protect water quality, DHEC issues construction permits for industrial waste water
treatment systems, which include mining process waste water ponds and rinse systems for cyanide
leaching operations. Construction permits also enforce DHEC's policy (no actual rules exist) of
requiring operators to place impermeable liners or asphalt pads under tailings impoundments and
leaching areas (Kennedy 1991).
Air Quality
South Carolina opacity requirements, which limit fugitive dust emissions from all sources including
mining operations, are more stringent than Federal opacity requirements. DHEC's Bureau of Air
Quality Control issues and enforces Air Emissions Permits under the South Carolina Pollution Control
Act and State Regulation 61-62.1. Facilities are issued five-year operating permits and construction
permits that establish emission limits for various units. In addition to these limits, the permit makes
operators subject to applicable New Source Performance Standards for Metallic Mineral Processing
(40 CFR Part 60, Subpart LL). The permit may also require that dust from haul roads and
turnaround areas be controlled by water sprays and water trucks and that stockpiles or waste rock
piles be sprayed with water when wind erosion creates excessive emissions. The Bureau of Air
Quality Control is authorized to seek civil and/or criminal penalties when permit requirements arc
violated by a facility. Formal facility inspections are conducted by DHEC on an annual basis.
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Mining Industry Profile: Gold
Solid Waste
Under State law, mining wastes are currently excluded from regulation as solid waste. However,
legislation that was under development, the Solid Waste Management Act, would broaden the State's
definition of "industrial solid waste" to include materials that have been chemically altered, including
wastes from cyanidation operations (Joy 1990). Operators would be required to obtain solid waste
permits (separate from operating permits) for the disposal of such chemically altered mining wastes.
Solid waste permits mandate controls for runoff water and require spreading and revegetation of the
waste to prevent erosion (South Carolina Code of Regulations 1980).
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Mining Industry Profile: Gold
1.8 REFERENCES
Ahsan, M.Q., et al. 1989. "Detoxification of Cyanide in Heap Leach Piles Using Hydrogen
Peroxide." In World Gold, proceedings of the First Joint SME/Australian Institute of Mining
and Metallurgy Meeting. R. Bhappu and R. Ibardin (editors).
American Geological Institute. 1976. Dictionary of Geological Terms, Revised Edition. Garden
City, NY: Anchor Press/Doubleday.
Beard, R.R. 1987 (March). "Treating Ores by Amalgamation." Circular No. 27. Phoenix, AZ:
Department of Mines and Mineral Resources.
Bonham, H.F., Jr. 1988. "Bulk Minable Gold Deposits of the Western United States." Economic
Geology, Monograph 6.
Bowhay, Dennis. 1983 (July 21). Notes concerning damage report and mineral rights. Washington
Department of Ecology.
Calgon Carbon Corporation. Undated. Granular Carbon For Gold Recovery. Brochure. Pittsburgh,
PA.
California Regional Water Quality Control Board, North Coast Region. 1987. Order No. 87-118,
Waste Discharge Requirements for Noranda, Inc., Noranda Grey Eagle Mines, Inc., and Siskon
Corporation. Sacramento, CA.
Cooper, A., and A. Kirkham. 1990 (September). An Overview of the Kensington Gold Project.
Preprint No. 90-436. Littleton, CO: .Society for Mining, Metallurgy, and Exploration, Inc.
Dadgar, A. 1989. "Extraction of Gold from Refractory Concentrates: Cyanide Leach vs. Bromide
Process." Presented at the Metallurgical Society Annual Meeting. Las Vegas, NV. February
27-March 2, 1989.
Devuyst, E.A., et al. 1990 (September). Inco's Cyanide Destruction Technology. Preprint No. 90-
406. Littleton, CO: Society For Mining, Metallurgy, and Exploration, Inc.
Doyle, P.M. (editor). 1990. Mining and Mineral Processing Wastes, proceedings of the Western
Regional Symposium on Mining and Mineral Processing Wastes. Berkeley, CA. May 30-June
1, 1990. Littleton, CO: Society for Mining, Metallurgy and Exploration, Inc.
Eurick, G. 1991 (January 2). Personal communication between G. Eurick, American Barrick
Mercur Mine, UT, and J. Rissing, Science Applications International Corporation, McLean,
VA.
Evans, D. 1987 (November). Personal communication from D. Evans, California Regional Water
Quality Control Board.
Fast, John L. 1988 (June). "Carbons-in-Pulp Pioneering at the Carlton Mill." Engineering &
Mining Journal. 56-57.
Griffith, J.S., and D.A. Andrews. 1981. "Effects of a Small Suction Dredge on Fishes and Aquatic
Invertebrates in Idaho Streams." North American Journal of Fisheries Management. 1(21): 28
1-69
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Hackel, R.P. 1990 (December). "Operating A Commercial-Scale Bioleach Reactor at the Congress
Gold Property." Mining Engineering.
Hurlbut, C.S., and C. Klein. 1977. Manual of Mineralogy. New York: John Wiley & Sons.
Jessup, D.H. 1988. Guide to State Environmental Programs. Washington, DC: Bureau of National
Affairs.
Joy, J. 1990 (January 14). Personal communication between J. Joy, South Carolina Department of
Health and Environmental Control, and J. Rissing, Science Applications International
Corporation, McLean, VA.
Kennedy, C. 1991 (February 26). Personal communication between C. Kennedy, South Carolina
Department of Health and Environmental Control, Land Resources Commission, and W.
Keeton, Science Applications International Corporation.
Kilcullen, K. 1990 (January 14). Personnel communication between K. Kilcullen, U.S. Fish and
Wildlife Service, and J. Rissing, Science Applications International Corporation, McLean, VA.
Kor, B.D. 1988 (March 23). Memorandum from B.D. Kor, California Regional Water Quality
Control Board, North Coast Region, to J. Baitge, U.S. Environmental Protection Agency.
LeHoux, P.L., and Holden, L. T. 1990 (December). "Atmospheric Carbon Elution Without the Use
of Cyanide at Barneys Canyon Mine." Mining Engineering: 1323.
Lopes, R.F., and R.J. Johnston. 1988 (August). "A Technical Review of Heap Leaching." In
Environmental Management for the 1990s, proceedings of the Symposium on Environmental
Management for the 1990s. Denver, CO. February 25-28, 1991. D.J. Lootens, W.M.
Greenslade, and J.M. Barker (editors). Littleton, CO: Society for Mining, Metallurgy, and
Exploration, Inc.
Miereau, D. 1991 (February 26). Personal communication between D. Miereau, Nevada Department
of Conservation and Natural Resources, Environmental Protection Division, Bureau of Mines
and Reclamation, and W. Keeton, Science Applications International Corporation.
Mine Safety and Health Administration. 1988. Closed Metal/Nonmetal Mine Employment and
Address Data Tape. Washington, DC.
Montana Department of State Lands. 1989 (September). Final Environmental Analysis:
Comprehensive Ufe-of-Mine Amendment, Operating Permit No. 00122, Kendall Venture. Helena.
MT.
Montana Tunnels Mining, Inc. 1990 (April). Environmental Assessment for Pegasus Gold
Corporation, Application for Amendment 003 to Operating Permit 00113.
National Institute of Occupational Safety and Health. 1990 (August 17). National Occupational
Health Survey of Mining: Gold Report. Morgantown, WV.
Park, C.F., Jr., and R.A. MacDiarmid. 1975. Ore Deposits. San Francisco: W. H. Freeman &
Company.
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Porath, H. 1981 (November 19). Memorandum from H. Porath to John Hodgson, State of
Washington Department of Ecology, regarding neutralization of silver mountain cyanide.
Radtke, A. 1980 (August). "Geology and Stable Isotope Studies of the Carlin Gold Deposit."
Economic Geology: 641-72.
"RIP Move in South Africa." 1991 (March). Australia's Mining Monthly.
Silva, M.A. 1988 (July). "Cyanide Heap Leaching in California." California Geology: 147-56.
Society of Mining Engineers, Mineral Processing Handbook 1985. Edited by N.L. Weiss, Volume 2.
Published by the Society of Mining Engineers, Littleton, CO.
Smolik, T.J., et al. 1984 (November). "Golden Sunlight - A New Gold Mining Operation." Mining
Engineering: 1557-61.
South Carolina Department of Health and Environmental Control. 1990. Spill Report and Emergency
Response Investigation (of spill on October 28, 1990).
Stanford, W.D. 1987 (April). "Amax Sleeper Mine Exceeds Expectations On All Counts As Low-
Cost Gold Producers." Mining Engineering (1987): 241-46.
Taff, C. 1991 (February 25). Personal communication between C. Taff, Nevada Department of
Conservation and Natural Resources, Environmental Protection Division, Bureau of Mines and
Reclamation, and W. Keeton, Science Applications International Corporation.
U.S. Department of the Interior, Bureau of Land Management. 1990a (August). "Modification of
Bonding Policy for Plans of Operation Authorized by 43 CFR 3809." Instruction Memorandum
No. 90-582. Washington, DC.
U.S. Department of the Interior, Bureau of Land Management. 1990b (August). "Policy for
Surface Management of Mining Operations Utilizing Cyanide or Other Leaching Techniques."
Instruction Memorandum No. 90-566. Washington, DC.
U.S. Department of the Interior, Bureau of Land Management, Needles Resource Area, and County
of San Bernardino, CA, Environmental Public Works Agency. 1989 (February). Castle
Mountain Project, San Bernardino County, California. Draft Environmental Impact
Statement/Environmental Impact Report. State Clearinghouse No. 880622708. Riverside, CA.
U.S. Department of the Interior, Bureau of Land Management, Needles Resource Area, and County
of San Bernardino, CA, Environmental Public Works Agency. 1990 (August). Castle Mountain
Project, San Bernardino County, California. Final Environmental Impact
Statement/Environmental Impact Report, 1990.
U.S. Department of the Interior, Bureau of Mines. 1978. Processing Gold Ores Using Heap
Leach-Carbon Adsorption Methods. Information Circular No. 8770. Washington, DC.
U.S. Department of the Interior, Bureau of Mines I983a Development Guidelines for Closing
Underground Mines: Michigan Case Histories Washington, DC.
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Mining Industry Profile: Gold
U.S. Department of the Interior, Bureau of Mines. 1984. Gold and Silver Leaching Practices in the
United States. Information Circular No. 8969. Washington, DC.
U.S. Department of the Interior, Bureau of Mines, Division of Minerals Availability. 1984
(November). Waste Disposal Activities and Practices: Copper, Lead, Zinc, Gold, and Silver
Waste Disposal Activities and Practices in the United States. Division of Minerals Availability
Open File Report. Washington, DC.
U.S. Department of the Interior, Bureau of Mines. 1985. "Gold" (by J.M. Lucas). In Mineral
Facts and Problems, 1985. Washington, DC: GPO.
U.S. Department of the Interior, Bureau of Mines. 1986. Precious Metals Recovery for Low-Grade
Resources, proceedings of the Bureau of Mines Open Industry Briefing Session at the National
Western Mining Conference. Denver, CO. February 12, 1986. Information Circular No.
9059. Washington, DC.
U.S. Department of the Interior, Bureau of Mines. 1990a. "Gold" (by J.M. Lucas). In 1988
Minerals Yearbook, Volume 1: Metals and Minerals. Washington, DC: GPO.
U.S. Department of the Interior, Bureau of Mines. 1990b. "Mining and Quarrying Trends in the
Metals and Industrial Minerals Industries" (by A.O. Tanner). In 1988 Minerals Yearbook,
Volume 1: Metals and Minerals. Washington, DC
U.S. Department of the Interior, Bureau of Mines. 1990c. "Gold" (by J.M. Lucas). In 7989
Minerals Yearbook. Washington, DC: GPO.
U.S. Department of the Interior, Bureau of Mines. 1992. "Gold 1991 Annual Report" (by J.M.
Lucas). Published in Washington, DC.
U.S. Department of the Interior, Bureau of Mines. 1991a (May). "Mining and Quarrying Trends in
the Metals and Industrial Minerals Industries" (by A.O. Tanner). In 1989 Minerals Yearbook.
Washington, DC: GPO.
U.S. Department of the Interior, Bureau of Mines. 1991b. Mineral Commodities Summaries, 1990.
Washington, DC.
U.S. Department of the Interior, Bureau of Mines. 1993. Mineral Commodities Summaries, 1993.
Published in Washington, DC.
U.S. Department of the Interior, Bureau of Mines. Undated(a). Gold Environmental Research
Highlights (by S.L. McGill and T.G. Carnahan). Reno, NV.
U.S. Department of the Interior, Bureau of Mines. Undated(b). Principal Mineral Areas of the
United States. Reference Map. Washington, DC.
U.S. Department of the Interior, Geological Survey. 1973. "Gold." United States Mineral
Resources. Professional Paper No. 820. Reston, VA.
U.S. Department of the Interior, Geological Survey. 1987. Mineral Deposit Models. Bulletin No.
1693. D.P. Cox and D.A. Singer (editors). Reston, VA.
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U.S. Environmental Protection Agency, Office of Solid Waste. 1985 (December). Report To
Congress: Wastes From the Extraction and Benefldation of Metallic Ores, Phosphate Rock,
Asbestos, Overburden From Uranium Mining, and Oil Shale. EPA/530/SW-85-033.
Washington, DC.
U.S. Environmental Protection Agency, Office of Water. 1986. Quality Criteria for Water.
EPA/440/5-86-001.
U.S. Environmental Protection Agency, Office of Water, Effluent Guidelines Division. 1982 (May).
Development Document for Effluent Limitations Guidelines and Standards for the Ore Mining
and Dressing Point Source Category.. Washington, DC.
University of California at Berkeley. 1988 (July). Mining Waste Study, Final Report. Prepared for
the California State Legislature. Berkeley, CA.
van Zyl, D.J.A., I.P.G. Hutchison, and J.E. Kiel (editors). 1988. Introduction to Evaluation,
Design and Operation of Precious Metal Heap Leaching Projects. Littleton, CO: Society for
Mining, Metallurgy, and Exploration, Inc.
Versar, Inc. 1985 (February). Quantities of Cyanide-Bearing and Acid-Generating Wastes Generated
by the Mining and Beneficiating Industries, and the Potential for Contaminant Release.
Prepared for the U.S. Environmental Protection Agency.
Weiss, N.L. (editor). 1985. SME Mineral Processing Handbook, Volume 2. New York: Society
of Mining Engineers.
Whiteway, P. (editor). 1990. "Mining Explained: A Guide To Prospecting and Mining." The
Northern Miner.
Windell, J.T. 1982. Comments and Criticisms on the Impacts of Recreational Dredging. Boulder,
CO: University of Colorado.
1
Winegar, B. 1991 (April 25). Personal communication between B. Winegar, Montana Bureau of
Lands, and J. Kissing, Science Applications International Corporation, McLean, VA.
Zaburunov, S.A. 1989 (August). "Ridgeway: Gold Deposit Producing Big Returns Through Good
Design." Engineering & Mining Journal: 52-55.
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Mining Industry Profile: Gold
APPENDIX 1-A
FLOW SHEETS OF SPECIFIC MINE OPERATIONS
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Oxide Oia
Jaw rVfQ
Dusher IA£V
Ora Cfcoiii
-Ca,bon
- Pi.fttMnt Sok^on
\
r-i Bal
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HJLJ
Caibon-|n-Leach Tanks
fi
r Screens
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Regeneration
K0n
-U
Strip Column
To Furnace
in Heap Leach Section
Tailings Pond
Cells
I
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Figure 1-12. Goldstrike Oxide Circuit
(Source: American Barrick Resources Corporation.)
I
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Catiodes
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'.".* *^*^*. I .*.
-'-'*iVi't'-*'V'*''* r
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Piagnant Sotufcm
Lean SoUkm
Pond
Ackl Wash
Vtaial
Batch
Counter
Cwiant
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Vassab
Carbon ntotnwallon Kfln
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Budon
Low Giada Piag
-- Watai/Bafien
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Figure 1-13. Goldstrike Heap Leach Circuit
(Source: American Barrick Resources Corporation.)
I
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IMM'I
Figure 1-14. Mercur Gold Mine, General Mining Operation
American Barrick Resources Corporation.)
I
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Figure 1-15. Sleeper Gold Mine, General Mining Operation
(Source: Amax Mineral Resources Corporation.)
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Mining Industry Profile: Gold
APPENDIX 1-B
NPL SITE SUMMARIES RELATED TO GOLD EXTRACTION AND BENEFICIATION
(from Mining Sites on the National Priorities List, Site Summary Reports,
Volumes I-V, Environmental Protection Agency, June 21,1991)
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Mining Industry Profile: Gold
CARSON RIVER SITE, LYON AND CHURCHILL COUNTIES, NEVADA
Operating History
The Carson River Superfund Site is a 50-mile stretch of the Carson River hi the Nevada counties of
Lyon and Churchill. The site begins in Brunswick Canyon between Carson City and Dayton and
extends downstream through the Lahontan Reservoir. This portion of the Carson River has been
contaminated by mercury from the historical operations of approximately 100 gold and silver
ore-processing mills. These mills lost an estimated 12 million to 18 million pounds of mercury to
either mill tailings or direct discharges to the Carson River during their active lives hi the late 1800's.
Now, the tailings piles left behind discharge an estimated 8 million pounds of mercury annually to the
river system. The Carson River site was proposed for the NPL in October 1989 and listed in August
1990.
Mercury is the contaminant of concern. The Carson River basin is-a large recreational and
commercial fishery resource. The basin is comprised of five hydrographic areas that include Carson
Valley, Eagle Valley, Dayton Valley, Churchill Valley, and the Carson Desert, totalling about 3,365
square miles. The east and west forks of the Carson River arise hi the Eastern Sierra, flow through
an intricate irrigation system within the Carson Valley and then coalesce to form the mainstream of
the Carson River. The river continues north through the Carson Valley, skirting the east side of
Eagle Valley, then turns northeast to pass through Brunswick Canyon. Continuing east through
Dayton Valley, the river flows into Churchill Valley, site of the Lahontan Reservoir, the main water
storage reservoir of the Newlands Irrigation Project. Below Lahontan Dam, a complex system of
canals and drains facilitate irrigation within the Carson Desert. The river and irrigation return flow
ultimately flow northeast to the Stillwater National Wildlife Refuge and the Carson Sink, or south to
Carson Lake.
An estimated 700,000 people annually use the river system for recreation, fishing, and irrigation.
Approximately 1,200 acres of food and forage crops are irrigated by water from the 50-mile stretch
of the Carson River hi the NPL site. The river is not used for drinking water. The Dayton Valley
Estates Water Company services 139 homes with water from an underground aquifer. The wells are
1.25 miles from mercury-contaminated tailings piles. In the Dayton Valley area, at least 226
households served by private wells are within 3 miles of either the Carson River or a
mercury-contaminated tailings pile. At least 30 of these homes are within 2,000 feet of either the
Carson River or a contaminated tailings pile.
The Carson River Site consists of sediments in the river and tailings piles associated with historical
milling operations along the river. Mercury-contaminated tailings piles have been found 5 miles up
Brunswick Canyon, 3 miles up Six Mile Canyon, and within the Carson Plains. Areas near the
Comstock Load, where extensive mining occurred, such as in Gold Canyon, may also be major
potential sources of mercury-contaminated mine tailings piles. Annual rains transport mercury from
the tailings piles to the Carson River.
The Nevada Department of Environmental Protection (NDEP) sampled one tailings pile located near
Six Mile Canyon in May 1986. The tailings pile was estimated to be approximately 100 feet long. 15
feet wide, with an average of 4 feet high, with mercury contamination of 493 ppm. The volume of
contaminated material is estimated to be 222 cubic yards. For Hazard Ranking System (HRS)
purposes, only one tailings pile was sampled to define the waste quantity for the Carson River
Superfund Site. According to the NDEP, this tailings pile is one of hundreds of mercury*-
contaminated tailings piles known to exist in Brunswick and Six Mile Canyons. Because of the larpc
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Mining Industry Profile: Gold
number of known contaminated piles, and because of the large amount of mercury lost during the
milling process, the waste quantity estimated from the one sampled tailings pile is expected to vastly
underrepresent the total waste quantity at the site.
A Remedial Investigation and Feasibility Study (RI/FS) for the Carson River site was initiated hi
September 1990. EPA's immediate priority was to analyze the options for the stabilization and
containment of the tailings piles. In addition, EPA is searching historical mining claims and land
ownership titles for Potential Responsible Parties.
Because of the historical nature of the mining operations which resulted in the mercury contamination,
there is little information available on the operating history of the site. During the late 1880's, ore
mined from the Comstock Lode near Virginia City was transported to any of 75 mills, where it was
crushed and mixed with mercury to amalgamate the gold and silver. Because water power was
available, 12 mill sites in the Brunswick Canyon area of Carson River dominated. It is not known
when operations at the mills ceased; however, the peak discharge reportedly occurred in the 30-year
period from 1865 to 1895. The mills have since been demolished.
Liquid mercury was imported and used in the amalgamation of gold and silver hi the ratio of 1:10,
mercuryrore. The average loss of mercury was 0.68 kg for each ton of ore milled. EPA estimates
that during the operation of these mills an estimated 14 million to 15 million pounds of mercury were
lost, of which only 0.5 percent was later recovered. Currently, an estimated 8 million pounds of
mercury-contaminated sediments are discharged annually from the tailings piles.
From 1906 to 1914, quicksilver was recovered from tailings at Douglas Mill in Six Mile Canyon.
The unknown operators of the quicksilver mine recovered approximately 75,000 pounds of mercury
using cyanide and flotation. Later, the Alhambra Mine Company also attempted to recover mercury
from contaminated waste piles. Alhambra used a cyanide leaching process to recover gold, silver,
and mercury. Alhambra's reprocessing operation lasted from December 1984 to July 1986; it is
unknown how much gold, silver, and mercury it recovered.
The Lahontan Reservoir has trapped Carson River sediments since it was constructed in 1915, acting
as a sink for mercury-contaminated sediments. It has not been determined if areas below the dam
will be included hi the RI/FS. It is possible that the results from an ecological assessment of the area
below the dam will request the inclusion of this area in the Carson River Superfund Site. The Carson
River and the Lahontan Reservoir are owned by the State of Nevada. The ownership of land adjacent
to the river is unknown but may be determined through a review of mining claims.
Environmental Damages and Risks
Neither the preliminary assessment nor the HRS worksheets discuss any known human effects
associated with mercury, the contaminant of concern. Possible exposure pathways are soil, air,
ground and surface water, and the food chain.
The greatest lexicological concern is methyl mercury, which is obtained from the consumption of
fish. The major source of methyl mercury in the environment is via microbiological conversion of
inorganic mercury by methanogenic bacteria in sediments of aquatic ecosystems. Organic mercury is
90 percent absorbed through the gastrointestinal tract and easily crosses the skin barrier. Once
absorbed, organic mercury is mobile hi the body, readily crossing into the brain as well as into a
fetus. Organic mercury is slowly broken down and excreted through feces. The halflife of organic
mercury is 65 days.
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Mining Industry Profile: Gold
During summer 1981, fish were collected to determine the mercury concentration in fish tissue^. 7
Results indicated that significant mercury accumulation is occurring within fishes of the Lahontan
Reservoir. Mercury concentrations in muscle tissue ranged from 0.11 mg/kg in young-of-the-year
white bass to 9.52 mg/kg in striped bass. Of the 53 muscle tissues analyzed, 36 (68 percent)
exceeded the 1 mg/kg "action level" considered safe by the Food and Drug Administration. Mercury
concentrations in heart tissues ranged from 0.17 mg/kg in carp to 5.58 mg/kg in striped bass. Liver
tissues had mercury concentrations ranging from 0.21 mg/kg in brown bullhead to 23.65 mg/kg in
striped bass. These levels are considerably higher than the 0.20 mg/kg considered as background for
fish. In general, mercury concentration within species increased with fish weight.
In 1986 the Nevada Department of Wildlife and Consumer Health Protection Services issued a fish
consumption advisory. The Department recommended that no more than one meal of fish (8 ounces)
caught in the Lahontan Reservoir or outfall waters below the reservoir should be eaten each week
because of possible toxicity from mercury. Specifically children or women of childbearing age should
not consume any fish from these waters. The health advisory was .expanded and reissued in 1987 to
indicate that no more than one meal of fish per month should be eaten, and walleye more than 21
niches long should not be eaten.
Approximately 1,200 acres of food and forage crops are irrigated by the Carson River between
Dayton and the Lahontan Reservoir. However, no studies indicate or describe the presence of
mercury in food or forage crops.
Although water drained from the Lahontan Reservoir through canals is used mainly for irrigation,
some canal water also drains into the Stillwater Marsh. Most of the water entering the marsh is
reportedly irrigation return flows. The Stillwater Wildlife Management Area is a major breeding
ground and stopover for hundreds of thousands of birds migrating on the Pacific Flyway. Fish and
bird kills in the Carson Sink have been attributed to increased salinization of the water and possibly
increased susceptibility of the wildlife to disease because of elevated levels of potentially toxic
elements such as arsenic and selenium. Mercury was not detected at the Stillwater Marsh Reservoir
outlet during NDEP sampling in 1983 and 1984.
CLEAR CREEK/CENTRAL CITY SITE; CLEAR CREEK AND GILPIN COUNTIES,
COLORADO
Operating History
The Clear Creek/Central City historical hardrock mining site is one of the most mined areas in
Colorado. Data indicate that up to 25 mines and 6 milling operations are operating in Gilpin and
Clear Creek Counties. The area also includes more than 800 abandoned mine workings and tunnels.
Mining activity in the Central City/Black Hawk area began in 1859 with placer gold mining.
Exploration tunnels were built from 1860 to 1937. Mining operations have included gold, silver,
copper, lead, and zinc. Although mining operations have varied recently because of fluctuating
market prices, historically 85 percent of the mining has been for gold, 10 percent for silver, and 5
percent for copper, lead, molybdenum, and zinc.
The Argo Tunnel, the most extensive and probably the most complicated of the five tunnel/mine
systems at the site, is an abandoned mine drainage and ore haulage tunnel. The Argo Tunnel is 4.16
miles long and is connected to eight major mining zones. There are a total of 36 laterals that branch
from the Argo Tunnel, 10 of which connect to mine systems. It is estimated that there are 91 surface
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Mining Industry Profile: Gold
openings and 21,400 feet of vein strike associated with the Argo Tunnel system. In 1982, it was
documented that the owner was using the tailings near .the tunnel portal as decorative landscaping and
was selling tailings samples to local distributors. The Argo mill site is also a local tourist attraction
as it is listed in the National Register of Historic Places.
In 1943, four miners were killed because of a blowout in the Argo Tunnel caused by mining
activities. In 1980, a second blowout occurred that was attributed to "natural" causes (i.e., the
collapse of "roof falls" used for damming water). As a result of the 1980 blowout, Clear Creek was
"grossly contaminated" and showed "serious violation of metal standards" the next day. (Note that
extensive information was not available for the other tunnel/mine systems as it was for the Argo
Tunnel.)
The Clear Creek/Central City site was nominated for the NPL in 1982 and added to the NPL in 1983.
A removal action was conducted by EPA's Emergency Response Branch at the Gregory Incline in
March 1987 to protect human health and the environment from hazards associated with the collapse of
a retaining crib wall. EPA removed the wall, decreased the slope of the tailings pile to stabilize it,
and then constructed a gabion-basket retaining wall.
Environmental Damages and Risks
The Phase n remedial investigation provided an assessment of the risks to human health associated
with the Clear Creek site. Overall, risks to human health are not expected from ingestion of surface
water when used as drinking water, ingestion of surface water while swimming, or ingestion of fish,
based on the exposure scenarios evaluated in this assessment. Potential risks are associated with
ingestion of ground water, incidental ingestion of tailings, and inhalation of airborne dust. Arsenic
contributes most significantly to risks from ground water and tailings. All of the chemicals evaluated
for the inhalation pathway pose risks to human health. Lead exposures from ingestion of soil, dust,
and ground water pose potential risks to children.
It was determined during the site investigation that Clear Creek, between the Argo Tunnel and
Golden, Colorado, "cannot support fish due to the contamination caused by mining activity."
Contaminants of concern for aquatic life are aluminum, arsenic, cadmium, chromium, copper,
fluoride, lead, manganese, nickel, silver, zinc, and low pH. During the Phase I remedial
investigation, concentrations of these chemicals in Clear Creek, North Clear Creek, and in the
wetland below National Tunnel were compared to Federal Ambient Water Quality Criteria (AWQC)
or to the Lowest-Observed-Effect Level (LOEL). Criteria for aluminum, cadmium, copper, lead,
manganese, silver, and zinc were exceeded in Clear Creek and North Clear Creek. In North Clear
Creek, criteria for pH were also exceeded. In the wetland, criteria were exceeded for aluminum,
cadmium, copper, manganese, silver, zinc, and pH.
The Phase n remedial investigation focused on the potential risks to trout and macroinvertebrates at
the site. It was found that trout could be acutely affected in the mainstem of Clear Creek, North
Clear Creek, and West Clear Creek, along with numerous tributaries of the streams. In addition,
virtually all of the tunnel discharges are expected to be acutely toxic to fish.
In the mainstem of Clear Creek and several of its tributaries, trout are at moderate to high risk of
adverse chronic (reproductive) effects. In North Clear Creek, there is a clear risk of adverse
reproductive effects. Potential risks of adverse reproductive effects are high in West Clear Creek
from Woods Creek to the confluence of Clear Creek. Chemicals in Lions Creek and Woods Creek
are likely to cause chronic effects.
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Mining Industry Profile: Gold
Zinc sediments could cause adverse reproductive effects in all stream segments that were evaluated.
Arsenic, cadmium, copper, and lead in sediment pose chronic risks at some locations.
CIMARRON MINING CORPORATION SITE, CARRIZOZO, NEW MEXICO
Operating History
The Cimarron Mining Corporation Superfund Site is 10.6 acres of privately owned land
approximately 1/4 of a mile east of Carrizozo, New Mexico, and approximately 100 miles south-
southeast of Albuquerque. It was originally constructed to recover iron from ores. The facility was
sold in 1979 and subsequently revamped to mill precious metals ore. The precious metal recovery
facility consisted of a conventional agitation cyanidation mill that resulted in the discharge of
contaminated liquids and stockpiling of contaminated tailings and waste trench sediment at the site.
.The mill operated without a State discharge permit. The mill was closed in July 1982 and the owners
of the facility filed for bankruptcy in July 1983.
Cyanide is the primary contaminant of concern; however, several metals were also identified as
contaminants of concern. Approximately 1,500 people live within 2 miles of the site. The Carrizozo
municipal wells are located within 2 miles of the site and were estimated in 1985 to serve a
population of 1,636. Contaminated media of greatest concern at the site are shallow ground water
and surface soils. The site was added to the NPL on October 4, 1989.
While conducting the remedial investigation at the Cimarron site, the existence of another abandoned
mill became known. The other location, known as Sierra Blanca, is 1 mile south of the Cimarron
site. The two mills were owned by the same parent company (Sierra Blanca Mining and Milling
Corporation) and, for a short period, operated concurrently. File information indicates a possible
spill at Cimarron prompted the relocation of milling operations to Sierra Blanca. Investigation of the
Sierra Blanca mill is being performed as a second operable unit.
The RI/FS was conducted between May 1989 and May 1990. In the Record of Decision (ROD)
(September 1990), EPA announced the selected remedy for the site. The selected remedy will pump
contaminated ground water from the shallow aquifer and convey it to the Carrizozo publicly owned
treatment works (POTW) for treatment, thereby eliminating the potential for migration of
contaminated shallow ground water to the deeper water supply aquifer. In addition, source control
measures would be implemented.
The mill facility was used to mill iron ores and recover iron using a magnetic separator during the
late 1960's and 1970's. Cyanide was not used in the original process and tailings from the mill were
transported off site and used as fill material in the Carrizozo area.
In 1979, Southwest Minerals Corporation bought the mill site and apparently began using a cyanide
process to extract precious metals from ores transported to the mill. Detailed information on the
metals extraction process operating between 1979 and 1981 was not available to EPA during their
remedial investigation. Cyanide was detected in an onsite discharge pit sediment sample collected by
the New Mexico Environmental Improvement Division (NMEID) in 1980, which indicates that
cyanide extraction was likely hi operation at that time.
Southwest Minerals expanded the operation hi 1981 even though they were operating without the
required discharge permit. The mill ceased operation in July 1982 following the June 23, 1982,
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Mining Industry Profile: Gold
receipt of an NMEID notice of violations for discharging into a nonpermitted discharge pit. The State
did not pursue legal actions against Southwest Minerals- and the company filed for bankruptcy in July
1983.
The EPA interviewed former mill employees and examined the onsite equipment during the remedial
investigation hi order to summarize the precious metals recovery operations employed at the site after
1981.
Ore was transported to and stockpiled on the site before it was transferred to a jaw crusher for size
reduction. After the ore was crushed, it was transferred to the mill building where it was placed in a
large hopper. Hydrated lime was added to prevent production of hydrogen cyanide gas and to
optimize the cyanidation reactions. The hopper fed a ball mill and rake classifier where cyanide
solution was added to the ore.
Sodium cyanide and potassium cyanide (stored onsite in 220-pound drums) mixed with water
composed the cyanide solution. In addition, two metal stripping chemicals (AMPREP and Enstrip
70), containing IS percent potassium cyanide, less than 1 percent lead oxide, and nitro-arornatic
compounds were apparently added to the cyanide solution to promote additional leaching of precious
metals.
The cyanide solution was mixed in two large vats, gravity fed to a large holding tank, and
subsequently pumped from this tank to the rake classifier, creating a cyanide-solution/crushed-ore
slurry. From the rake classifier, the slurry was pumped to a heated, agitated vat. Heating the slurry
promoted the reaction of cyanide with precious metals. The slurry was pumped to a second agitated
vat and then to each of four thickeners. Pregnant (precious metal-containing) cyanide solution was
skimmed from the top of each thickener and routed (countercurrent to the direction of slurry flow)
back to the second agitated vat. Pregnant solution contained in the agitated vats was gravity fed to a
large metal holding tank near the lab building.
Pumped from the holding tank, pregnant solution was fed through small pressure filters to an
electrowinning cell in the lab building. Precious metals were deposited onto aluminum plates, which
were heated hi an outside kiln to separate the aluminum from the dor£ (unrefined metals).
The barren cyanide solution contained free cyanide and metal-cyanide complexes of copper, iron,
nickel, cobalt, zinc, and other impurities. Most of the barren solution was pumped to two cement
block-lined trenches near the main operations building for recycling into the mill circuit, but a portion
was discharged to the unluied discharge pit to avoid build-up of metal impurities that would
subsequently interfere with the dissolution and precipitation of gold in the cyanidation process.
Backwash waste solution from the pressure filters was disposed of in the discharge pit. Chlorine was
added to the waste solution to oxidize the cyanide. Analyses of samples from the pit indicate that this
treatment was not effective. The ineffectiveness of the chlorine treatment was possibly because of
poor application methods and/or the existence of a significant quantity of complex cyanide forms not
affected by chlorine. The cement block trenches and the unlined discharge pit are the two main
sources of cyanide migrating into the ground water at the site.
Solids from the last thickener in the series were pumped through a solid separator and were conveyed
and discharged to a truck for transport to the tailings piles. The remaining fluid fraction (and
small-size solids) were apparently gravity fed to the two cement block trenches for recycling into the
cyanidation process. As sediment built up in the trenches, it was removed and stockpiled onsite.
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Mining Industry Profile: Gold
Environmental Damages and Risks
Site contamination was revealed in the analyses of soil samples collected during a 1980 NMEID field
inspection. This initial sampling revealed the presence of cyanide and elevated metals in shallow
ground water, soil, and mill tailings. Additional investigations, including the RI/FS, delineated the
extent of cyanide and metals contamination at the Cimarron site.
The June 1990 Remedial Investigation Report presents an endangerment assessment of the potential
human health risks associated with the existing conditions at the site. Land surrounding the site is
used for agricultural, commercial, recreational, and residential purposes. An estimated total
population of 1,500 lives within a 2-mile radius of the site. The main mill facility is fenced to
prevent access, including the tailings disposal area.
The total population served by ground water from the aquifer of concern within 3 miles of the site
was estimated hi November 1985 to be 1,636. This includes 1,500'people served by the town of
Carrizozo municipal water system. The municipal supply wells are located within a 2-mile radius of
the site. The closest drinking water well is located about 0.8 miles from the site. An onsite well was
used for industrial purposes. The risk assessment identified cyanide and several metals as
contaminants of concern.
The risk assessment determined that, under a current exposure (for an offsite resident) scenario, it is
unlikely that human receptors will experience adverse noncarcinogenic health effects. The highest
excess cancer risk for exposure resulting from site visits or inhalation of fugitive dust in Carrizozo is
4.7 x 10-*.
The risk assessment determined that, under a future exposure (for an onsite resident) scenario, there
may be concern for potential noncarcinogenic health effects hi children or adults ingesting
contaminated ground water. The highest excess cancer risk is 8.7 x 10* resulting from incidental
ingestion of soils.
SILVER MOUNTAIN MINE, LOOMIS, WASHINGTON
Operating History
Underground mining for silver, gold, and copper began at the site in 1902. EPA's remedial
investigation states that the mine was active in 1936, 1943, 1945, and 1956, and that by 1956 the
mine had approximately 2,000 feet of underground mine workings and a few thousand tons of mine
dump. A mill was built in 1952 but may have never been used. No other records of production were
known to exist. From late 1980 to late summer 1981, Precious Metals Extraction (PME), Ltd.,
constructed and operated the leaching operation described above. This operation was abandoned in
1981 with no site closure or cleanup of contaminated material.
Detailed records on the process used by PME and the construction of the leach heap and leachate
collection pond were not available to EPA during their remedial investigation. However, field
observations and data collected by the Bureau of Mines during their investigation in 1989 provide
basic data on the leaching process and unit construction:
"PME cleared an area of approximately 180 feet by 140 feet, adjacent to existing mine dumps. A
leach pad base of sandy soil up to 3 feet thick and graded with a 2.5 percent slope to the southwest
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Mining Industry Profile: Gold
was prepared. At the southern end of the leach pad a rectangular trench 7 feet by 75 feet and
averaging 4 feet in depth was dug as a leachate collection pond. The soil base and pond were then
covered with a green 20-mil thick plastic liner. Another layer of sandy soil, from 0 to 6 inches thick
was then placed over the plastic liner. Approximately 5,300 tons of material from the mine dump
were loaded onto the pad. The prepared heap was approximately 100 feet long, 105 feet wide, and
14 feet high." As stated above, several tons of caustic soda and lime, and approximately 8,000
pounds of sodium cyanide were combined with water and applied to the leach heap.
Processing of the leachate to remove the precious metals may have been accomplished through direct
electroplating or by using activated carbon, but information on the processing is not conclusive.
Drums containing activated carbon were found onsite. The operation was abandoned in late summer
1981 without neutralizing the solution in the leachate pond or materials in the leach heap. Empty
cyanide drums and large containers of activated carbon also remained onsite.
Environmental Damages and Risks
Initial interest in the site began in 1981, when the owner of the surface rights informed the Okanogan
County Health Department of the heap leaching operation (U.S. EPA, Region X 1990a; Bowhay
1983). Originally, the Washington Department of Ecology responded to the threat caused by the
cyanide in the leachate collection basin. Upon further investigation, EPA found additional potential
sources of contaminants (the leach heap, mine dump, mine drainage, and bedrock) and additional
contaminants of concern (arsenic and antimony, as well as cyanide).
The Remedial Investigation Report, completed in January 1990, presents a human health risk
assessment for the site. The risk assessment identifies arsenic, antimony, and cyanide as the
contaminants of concern. Population near the site is sparse, with fewer than 20 people within a 3-
mile radius served by drinking water wells. The land in closest proximity to the site is used for cattle
grazing. The closest domestic water well is approximately 3 miles south of the site. Currently, the
closest livestock watering well is 2 miles from the site. Other concerns include use of the site by local
teenagers who may potentially become exposed to the contaminants.
Arsenic, antimony, and cyanide are the major contaminants in water. Based on future exposure
scenarios, exposure to arsenic in water could result in an increase in cancer risk of 2 x 10^. There is
also risk of noncarcinogenic effects from arsenic, cyanide, and other chemicals.
The major contaminant in soil is arsenic. Based on future exposure scenarios, exposure to soil could
result in an increased cancer risk of 2 x 10'3, as well as noncarcinogenic effects.
WfflTEWOOD CREEK SITE, LAWRENCE, MEADE, AND BUTTE COUNTIES, SOUTH
DAKOTA
Operating History
Homestake Mining Co. initially began gold mining near Lead, South Dakota, in the late 1870's.
Approximately 110 million tons of ore were produced during the operating history of the site.
Mining operations extended to a depth of more than 8,000 feet below the land surface. The first
milling operations used crude methods to crush the ore and recovered gold by gravity or by
amalgamation with mercury. Mercury amalgamation was used primarily until 1971 when cyanide
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Mining Industry Profile: Gold
began to be used exclusively. It is estimated that between 1/8 and 1/2 ounce of mercury per ton of
ore crushed was lost, with 50 percent of this being discharged in the waste stream.
Tailings and untreated waste water were continuously discharged into Whitewood creek during the
100-year operating history of the site, excluding a 5-year period during World War n when the mine
was closed. Tailings were discharged directly into the creek or its tributaries from a number of mine
operators until approximately 1920, after which Homestake was the only source of tailings discharge.
The discharge of tailings was a common practice of the tune. In 1963, up to 3,000 tons of tailings
and 12,500 tons of water were being discharged per day into Whitewood Creek.
In the 1920's, ball and rod mills were brought into use at the mine. The ball and rod mills created
finer-grained tailings, or "slimes." After 1935, sand-sized tailings were typically used to backfill
mined areas, and the "slimes," as well as some coarse-grained sands, were discharged into
Whitewood Creek. This practice continued until 1977. In 1977, Homestake constructed a tailings
impoundment hi the upper reaches of the watershed at Grizzly Gulch, located in the upper reaches of
the Whitewood Creek watershed, to treat residual slimes and process waters. In December 1984, a
waste water treatment system was put into operation to treat water from the tailings impoundment and
the mine. The plant uses rotating biological contractors to remove cyanide and ammonia, iron
precipitation and sorption to remove metals, and sand filtration to remove suspended solids from mine
water. The solids are returned to the tailings pond and the water is discharged into Gold Run Creek,
which runs into Whitewood Creek between the towns of Lead and Dead wood. This treatment was
then supplemented to meet the newly imposed NPDES and State stream standards when Homestake
began the research and development of a new waste water treatment plant using a bio-treatment
process. This discharge is monitored to meet requirements of the CWA.
From the 1870's to the end of the century, a substantial portion of the discharged tailings were
distributed hi and on the alluvial materials of the floodplain because Whitewood Creek was a small
meandering stream with insufficient capacity to transport the large quantity of tailings. Over tune, the
discharged tailings and some alluvial material filled the meanders of the creek, which straightened its
channel and increased its gradient. This, hi turn, caused Whitewood Creek to downcut its channel to
the resistant shale bedrock, which today forms the channel bottom for most of the length of the 18-
mile stretch of the site. As a result of the changes hi the sediment-carrying capacity of Whitewood
Creek, little deposition of tailings on the alluvial materials is believed to have occurred beyond the
turn of the century.
Environmental Damages and Risks
Systematic studies of the Whitewood Creek area by the South Dakota Department of Health, which
began hi 1960, quantified the solids and cyanide loading to the creek and recommended further
studies. In 1965, a study by the South Dakota Department of Game, Fish, and Parks determined that
aquatic bottom organisms were not present hi Whitewood Creek downstream from the waste
discharges. Several additional studies, which focused on the possible serious environmental hazard
created by mercury contamination, led to the discontinuance of mercury use in gold recovery
operations hi December 1970.
A study published hi 1978 found arsenic concentrations ranging from 2.5 to 1,530 /tg/1 hi ground
water from areas with large tailings deposits. As a result of these studies, it was concluded that the
Whitewood Creek area would remain highly contaminated until the discharge of tailings was
discontinued. This resulted hi the construction of Homestake's Grizzly Gulch Tailings Disposal
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Mining Industry Profile: Gold
Project, which became fully operational on December 1, 1977 and produced a dramatic improvement
in the physical appearance and quality of the creek waters.
The potential lifetime excess carcinogenic risks from exposure to arsenic through ingestion of soils
and ground water within the site for both the representative and maximum exposed site resident were
determined to be unacceptable. For the representative and maximum exposed site resident, ground
water risks were determined to be 1.9 x 10"4 and 4.4 x 10'3, and soil risks were determined to be 2.4
x 10"4 and 2.6 x 10'3, respectively, all of which are greater than the acceptable Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA) level of 1 x lOr4. Potential
risks to recreational visitors were determined to be acceptable. The potential risk to the representative
site resident from the consumption of ground water is acceptable when evaluated with respect to the
National Primary Drinking Water Standard. The greatest potential risk to the representative site
resident comes from surface soils on residential properties that have elevated arsenic levels rather than
tailings deposit area soils or irrigated cropland soils. Elevated arsenic levels on residential properties
are the result of past deposition or the use of tailings as road gravel.
i
Elevated arsenic concentrations in the downgradient alluvial ground waters present a possible future
unacceptable potential risk. The current potential risk of these ground waters was not considered
because they are not used as a water supply and a state regulation prohibits the installation of water
supply wells within the 100-year floodplain of Whitewood Creek, within which these ground waters
are situated.
Potential noncarcinogenic health effects associated with exposure to arsenic, cadmium, chromium,
copper, lead, manganese, mercury, and nickel through the ingestion of soils and ground water within
the site were determined to be unacceptable for the maximum exposed site resident. Effects for all
other groups were determined to be within acceptable levels. The unacceptable level for the
maximum exposed site resident assumed residency on the tailings deposit areas, the concomitant high
rates of incidental ingestion of the soils in these areas, and the consumption of downgradient alluvial
ground waters, scenarios not currently encountered by site residents but that could be encountered in
the future.
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Mining Industry Profile: Gold
APPENDIX 1-C
3040) SITES RELATED TO GOLD MINING ACTIVITIES
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Mining Industry Profile: Gold
Sunnyside Gold (Mayflower Mill)
The Mayflower Mill is an active operation that processes ore from the Sunnyside Mine, which
produces gold and silver plus sulfides of lead, zinc, and copper. The waste water discharge from the
mill has been identified as a point source that contributes significantly to contamination (e.g., high
metals concentrations, primarily zinc, and whole effluent toxicity) in Cement Creek and the Animas
River into which the creek flows. The development of a control strategy for this facility to ensure
compliance with applicable water quality standards is complicated with numerous other point- and
nonpoint-source mining discharges, which have an impact on receiving waters.
Clear Creek/Central City
Including Clear Creek on the 304(1) list was intended to address all of the surface water discharges,
primarily from mining operations, which have led to identification of Clear Creek as an NPL site
(ranked No. 174 in 1983). EPA has conducted extensive sampling 'and analysis to characterize the
contamination (high metals concentration and toxicity to aquatic life both in Creek water and
sediments) and identify contributing discharges. Contaminants of concern include aluminum, arsenic,
cadmium, chromium, copper, fluoride, lead, manganese, nickel, silver, zinc, and pH. The greatest
toxic effects have been found to occur during seasonal high-flow periods and storms. Active and
inactive mine sites in numerous mining sectors with point- and nonpoint-source discharge are the
responsible parties.
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Mining Industry Profile: Gold
APPENDIX 1-D
COMMENTS AND RESPONSES
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Mining Industry Profile: Gold
Appendix 1-D: Comments on the Draft Industry Profile and EPA Responses
A draft of the Industry Profile: Gold was provided for review and comment to the following: U.S.
DOI, Bureau of Mines, the Western Governors' Association, the Interstate Mining Compact
Commission, the American Mining Congress (AMC) and various Environmental Interest Groups for
their review and comment. Approximately 450 comments were submitted to EPA by the following
six reviewers: the Bureau of Mines, American Barrick Resources Corporation, Hecla Mining
Company, Homestake Mining Company, Newmont Gold Company, and The Precious Metal
Producers. The comments included technical and editorial changes, as well as comments on the scope
of the Profile and how it relates to authorities provided under RCRA Subtitle D.
Because several general concerns were raised by a number of commenters, EPA has grouped the
comments into two categories. The first includes seven general concerns that were raised by all
commenters. These are addressed in the first section below. The second category of comments
includes technical comments on this Profile, which were raised by specific reviewers, rather than the
group as a whole. These are addressed in the second section below. All other comments, including
minor technical and marginal notes, have been incorporated into the revised Profile; EPA believes
they have served to improve the document's accuracy and clarity. EPA would like to thank all the
agencies, companies, and individuals for their time and effort spent reviewing and preparing
comments on the Profile.
General Issues Pertaining to All Profiles
1. Comment: Several commenters objected to the use of hypothetical phrases like "may cause"
or "may occur." Their use was characterized as misleading and inappropriate in describing
environmental impacts in an Industry Profile of this type.
Response: It is felt that the descriptions of conditions and impacts that may occur regarding
potential effects is appropriate in many cases, since the intent of the relevant sections of the
profiles is to describe potential impacts that may occur as a result of extracting and
beneficiating ores and minerals. As noted in the responses to related comments below, EPA
has extensively revised the sections of the profiles addressing environmental effects. They are
now more focussed and direct; they describe, in general terms, a number of specific types of
impacts that can occur under particular conditions or in particular environments.
2. Comment: A related issue raised by commenters was that EPA did not balance the profile by
describing environmental protection practices currently followed by the mining industry.
Instead, the commenters were critical that EPA selected the worst sites to describe, which
represent only a small number of mines and even a few clandestine operations.
Response: It is felt that the Profile (and related site reports) represents current environmental
management practices as described in the current literature.
3. Comment: Commenters on each of the profiles were concerned that the sites described in the
discussion of environmental effects were under some other regulatory authority (e.g.,
CERCLA).
Response: As noted above, the relevant sections of the profiles have been revised
extensively. However it is felt that, with proper qualification, sites under other regulatory
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Mining Industry Profile: Gold
authorities, including CERCLA, are relevant to any examination of actual or potential
environmental effects.
4. Comment: Commenters were concerned that the Profile considered materials other than those
considered "wastes11 under RCRA.
Response: Since the profile is intended to identify the potential environmental effects of
mining, it was considered appropriate to discuss both wastes and materials that have similar
potential to pose risks to human health and the environment.
5. Comment: Many commenters recommended that the mitigating effects of site-specific factors
on potential environmental effects be discussed.
Response: As noted above, the relevant sections of the profiles have been revised including
the addition of language that emphasizes the site-specific nature of potential environmental
effects.
6. Comment: Many commenters recommended that the effectiveness of State regulatory actions
in preventing adverse environmental effects be integrated into any discussion of potential
effects.
Response: The Profile has been amended to reflect the fact that State requirements can
substantially reduce or eliminate many adverse environmental effects.
7. Comment: A number of comments were received on the table in each draft profile that cited
NIOSH data on the quantities of certain chemicals found on mine property and that included
worker exposure limits. Commenters questioned the data's accuracy and relevance.
Response: The table has been replaced with a simple list of chemicals typically found on
sites.
Technical Issues Pertaining to the Gold Profile
8. Comment: The Profile ignores state-led regulatory programs.
t
Response: Due to the number of States with programs regulating the mining industry, and the
wide variation in those programs, it was decided to address the regulatory programs
implemented by two States, Nevada and South Carolina. Nevada was chosen because of the
vast majority of current gold mining occurs in that State. South Carolina was selected to
reflect mining regulation in a wet climate. A discussion of these is presented in both the draft
Profile and this revised document.
10. Comment: The Profile is a 1991 release. The massive expansion of the industry since that
time is masked by the use of 1988 data to characterize the industry.
Response: The most recent publicly available information at the time of the Profile's
preparation (late 1990) was used in the draft profile. The draft has been revised to include
updated information (as of April 1992) from the Bureau of Mines.
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Mining Industry Profile: Gold
11. Comment: The Profile does not quantify the magnitude of known or potential contamination.
Response: As noted in the first section above, the primary purpose of the profile is not to
catalog or rank environmental effects. The Profile has been revised to clarify its intent.
12. Comment: The use of the word extraction is unclear. Extraction, in the metallurgical sense,
refers to a method used to remove the values from the ore; in the Profile it is analogous to
mining.
Response: As described in the profile, in 1980 Congress conditionally exempted from RCRA
Subtitle C, wastes from the "extraction, beneficiation, and processing of ores and minerals".
In this case, the term extraction is analogous to mining.
13. Comment: Too much time is spent on mining and beneficiation techniques that relate to an
insignificant portion of the industry. Examples include open cut and block caving methods;
flotation, gravity concentration, and in situ leaching. This results hi speculation about impacts
from techniques that are of minimal importance.
Response: Relevant portions of the profile have been revised substantially hi response to this
comment. The description of mining methods has been deleted. Text describing by-product
gold from base metal operations (flotation) and gravity concentration has been edited
significantly. The in situ discussion simply references a pilot-scale study, and thus remains
largely unchanged in the revised profile.
14. Comment: The profile ignores regulations protecting against acid drainage,
Response: The Profile has been revised and clarified regarding the discussion of acid
drainage. Nevada's regulations governing acid drainage are discussed in the section
concerning that State's Water Pollution Control Permits.
IS. Comment: Sulfide ores are rarely, if ever, used in heap leaching operations.
Response: The description of heap leach operations has been extensively revised based on
reviewers comments. The text concerning the use of sulfide ores has been modified
accordingly.
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Mining Industry Profile: Gold
APPENDIX 1-E
ACRONYM LIST
1-96
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Mining Industry Profile: Gold
ACRONYM LIST
AMD acid mine drainage
AWQC Ambient Water Quality Criteria
BATVBPJ best available technology/best professional judgment
BLM Bureau of Land Management
BMP best management practice
BPJ best professional judgment
CAA Clean Air Act
CCD continuous countercurrent decantation
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CFR Code of Federal Regulations
CIC carbon-in-column
CIL carbon-in-leach
CIP carbon-in-pulp
CWA Clean Water Act
DHEC Department of Health and Environmental Control
dscm dry standard cubic meter
FLPMA Federal Land Policy and Management Act
FS Forest Service
FWS Fish and Wildlife Service
GA Groundwater A
GB Groundwater B
GC Groundwater C
HOPE high-density polyethylene
HRS Hazard Ranking System
ICSs individual control strategies
IM Instruction Memorandum
kg kilogram
Ib. pound
LOEL Lowest-Observed Effect Level
MCL Maximum Contaminant Level
mg/1 milligrams per liter
MSHA Mine Safety and Health Administration
NAAQS National Ambient Air Quality Standards
NEPA National Environmental Policy Act
NESHAP National Emission Standards for Hazardous Air Pollutants
NIOSH . National Institute for Occupational Safety and Health
NMEID New Mexico Environmental Improvement Division
NPDES National Pollutant Discharge Elimination System
NPL National Priorities List
NPS National Park Service
NSPS New Source Performance Standard
NTIS National Technical Information Service
oz/t troy ounces per ton
PME Precision Metals Extraction. Ltd.
ppm parts per million
PSD prevention of significant deterioration
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Mining Industry Profile: Gold
ACRONYM LIST (continued)
RCRA Resource Conservation and Recovery Act
RI/FS Remedial Investigation and Feasibility Study
RIP Resin-in-Pulp
ROD Record of Decision
SHDG sediment-hosted disseminated gold
SIP State Implementation Plan
TSCA Toxic Substance Control Act
TSS total suspended solids
USC U.S. Code
U.S. DOI U.S. Department of the Interior
U.S. EPA U.S. Environmental Protection Agency
U.S. GS United States Geological Survey
VLDPE very low-density polyethylene
WAD weak acid dissociable
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Mining Industry Profile: Gold
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Mining Industry Profile: Gold
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Mining Industry Profile: Gold
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Mining Industry Profile: Gold
1-102
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Site Visit Report: Brewer Mine
MINE SITE VISIT:
BREWER GOLD COMPANY
U.S. Environmental Protection Agency
Office of Solid Waste
401 M Street S.W.
Washington, D.C. 20460
-------
Site Visit Report: Brewer Mine
2.0 SITE VISIT REPORT: BREWER MINE
2.1 INTRODUCTION
2.1.1 Background
The U.S. Environmental Protection Agency (EPA) is assisting states to improve their mining
programs. As part of this ongoing effort, EPA is gathering data related to waste generation and
management practices by conducting site visits to mine sites. As one of several site visits, EPA
visited Brewer Gold Company's facility near Jefferson, South Carolina on September 24, 1991.
Sites to be visited were selected to represent both an array of mining industry sectors and different
regional geographies. All sites visits have been conducted pursuant to RCRA Sections 3001 and 3007
information collection authorities. When sites have been on Federal land, EPA has invited
representatives of the land management agencies (Forest Service and/or Bureau of Land Management)
to participate. State agency representatives and EPA regional personnel have also been invited to
participate in each site visit.
For each site, EPA has collected information using a three-step approach: (1) contacting the facility
by telephone to obtain initial information, (2) contacting state regulatory agencies by telephone to get
further information, and (3) conducting the actual site visit. Information collected prior to the site
visit is then reviewed and confirmed at the site.
In preparing this report, EPA collected information from a variety of sources, including the Brewer
Gold Company, the South Carolina Department of Health and Environmental Control (DHEC), the
South Carolina Land Resources Commission (LRC), information from telephone conversations with
Brewer Gold Company and with DHEC and LRC, and from other published sources. The following
individuals participated hi the Brewer Gold Company site visit on September 24, 1991:
Brewer Gold Company
Ken Barnes, Mine Maintenance Superintendent (803) 658-3039
Gary Froemming, Mine Supervisor (803) 658-3039
R.M. Mattson, General Manager (803) 658-3039
Jaye Pickards, Plant Supervisor (803) 658-3039
Scott Wanstedt, Environmental Engineer (803) 658-3039
Mark Zwaschka, Geologist (803) 658-3039
2-1
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Site Visit Report: Brewer Mine
B.C. Land Resources Commission. Division of Mining and Reclamation
Craig Kennedy, Assistant Director (803) 734-9100
Pat Walker, Director (803) 734-9100
S.C. Department of Health and Environmental Control
Ed E. Hart, Facility Evaluator (803) 662-3522
Marion R. Rembert, District Director (803) 662-3522
U.S. Environmental Protection Agency
Van Housman, Chemical Engineer (703) 308-8419
Science Applications International Corporation
Jack Mozingo, Environmental Scientist (703) 734-2513
Jonathan M. Passe, Regulatory Analyst (703) 821-4831
Participants in the site visit were provided an opportunity to comment on a draft of this report.
Comments were submitted by the Brewer Gold Company and the State of South Carolina. Brewer
Gold Company comments are presented in Appendix 2-A; State Comments are presented in
Appendices 2-B and 2-C. EPA's response to the Brewer Company's and State comments are
presented in Appendices 2-D and 2-E.
2.1.2 General Facility Description
The Brewer Gold Mine is located hi Chesterfield County, South Carolina, approximately 1.5 miles
west of the town of Jefferson (see Figure 2-1). The mine site is situated on a ridge between Lynches
River on the west and Little Fork Creek (a tributary to Lynches River) to the east. Highway 265
bounds the property on the southern side (Brewer Gold Company Description). The predominant
land uses within four miles of the Brewer site include urban (the town of Jefferson), fanning,
commercial/light industry (poultry), and undeveloped forest area. There is no zoning in Chesterfield
County.
The Brewer Gold facility is sited on privately owned lands. The total area disturbed by the facility is
estimated to be slightly over 200 acres, with a reserve (currently inactive) of an additional 20 acres.
Ore is mined from the Brewer Pit using open pit methods, although the current pit intersects old
underground workings. Ore is hauled to on-site crushers, agglomerated, and conveyed to a heap
leach pad. The Brewer Gold facility uses a cyanide solution to recover gold from ore that has been
crushed and placed on leach pads. Leachate collected from the leach heaps is carbon stripped and
gold is then electrowon, electroplated, and melted into dore bars in the facility's crucible furnace.
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a*
Site Visit Report: Brewer Mine
BOCK Hltt»\
GREENVILLE /^
AREA OF MAP BELOwT"
SOUTH CAROLINA
Lincaitc Co
BMEWEK
PROJECT
LOCATION
Otrimgion Ca.
NO.
05621
OAT6
4/90
REVISION
0
STDTEM ROBERTSON & KIRSTEN (U.S.)
Consulting Enainecra Jc Scitntists
FIGURE 1
Marlboro Co
PROJECT
LOCATION MAP
Figure 2-1. Location of Brewer Gold Mine
(Source: Figure 1 in Brewer Gold Company, 1990b)
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Sire Visit Report: Brewer Mine
Gold was first mined at the Brewer site in the late 1820s; by the late 1800s, a substantial operation,
including a 40-stamp mill, was underway at the property. Operations ceased in 1941, and significant
exploration activity did not restart until the late 1970s, when gold.prices sparked renewed interest in
the area. The corporate predecessor to Westmont, which was Brewer Gold Company's former parent
company, commenced exploration in 1983 and, during the period 1984 through 1986, carried out
exploration and engineering feasibility studies, leading to a project go-ahead decision in January 1987.
The construction period lasted six months, and the first gold was poured in early August 1987
(Brewer Gold Company, undated).
Between June 1987 and the end of March 1991, Brewer Gold Company removed from its pit a total
of 9.2 million tons1 of combined ore and waste, of which 3.8 million tons were ore that was crushed
and beneficiated. Cumulative gold production from the Brewer site prior to the 1980s is estimated at
22,000 troy ounces. Since start-up hi 1987, through March 1991, Brewer Gold Company has
produced 118,087 ounces. Thus, the estimated total production to date from the Brewer site is
estimated to be hi excess of 140,000 ounces. Small amounts of silver are also recovered at the
facility (Brewer Gold Company, undated).
Production at the Brewer mine was suspended following a cyanide spill caused by a dam failure on
October 28, 1990. Production resumed on June 20, 1991. Projected 1991 production was 23,000
troy ounces of gold; projected 1992 production was 38,000 troy ounces. The total life of the mine
was originally estimated to be approximately 5 years, with 2 to 2.5 years of known, minable reserves
remaining at the time of the site visit. Additional exploration on-site and hi nearby areas may extend
the life of the mine (EPA, 1991).
2.1.3 Environmental Setting
2.1.3.1 Surface Water
The immediate discharge point for the Brewer Gold Company facility is Little Fork Creek. The
Creek is designated by the State of. South Carolina as a Class B water (i.e., suitable for secondary
contact recreation, as a drinking water supply after conventional treatment, and for fishing,
agricultural, and industrial uses). The principle use is for cattle watering. The Creek has no
significant floodplain since it occupies a relatively narrow valley. Little Fork Creek has several
smaller tributaries, including a stream that receives discharge from an adit from the historic workings
and which drams the present pit. Little Fork Creek discharges to Fork Creek about two miles
downstream from the Brewer site; Fork Creek enters Lynches River about one-half mile below that.
'In this report, "tons" refers to short tons (2,000 pounds). "Ounces" refers to troy ounces (1 troy
ounce is equal to 0.068S7 pound).
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Site Visit Report: Brewer Mine
Average monthly stream flows in Little Fork Creek range from 3.9 cubic feet per second (cfs), or
1,743 gallons per minute (gpm), in October to 34.4 cfs (15,456 gpm) in March. In Fork Creek,
average monthly stream flow ranges from 6.3 cfs in October to 55.8 cfs in March (Brewer Gold
Company, 1991b).
A water quality study was conducted on Linle Fork Creek as part of an overall Ecological Assessment
performed by a Brewer contractor for the initial mining permit application. The study found pH
values in the Creek and its tributaries ranging from 6.49 to 7.35. At sampling point LCF-2A,
upstream of Brewer's permitted discharge point but affected by discharge from an adit from the
historic mine workings, pH was measured at 3.55. Samples from this location also indicated elevated
sulfate levels due to the presence of oxidized pyrite. Concentrations of barium, cadmium, chromium,
lead, mercury, selenium, silver, and zinc were at or below detection limits for all creek water
samples: Arsenic concentrations were quantifiable, but all were well below EPA's 0.05 mg/L
drinking water standard. Copper levels at the mine adit discharge were recorded at 0.26 mg/L and
were below the detection limit at all other sampling stations. Iron concentrations at all sampling
points in the Creek ranged from 2.10 mg/L to 2.99 mg/L. All measured tributaries, however,
exhibited lower iron levels (Environmental and Chemical Services, Inc., 1987).
Subsequent to a release of cyanide solution into the Creek in October 1990, Brewer commissioned a
study of macroinvertebrates and fish communities in Little Fork and Fork Creeks (the facility's
current NPDES permit requires macroinvertebrate studies twice a year; the permit was being revised
at the time of the site visit and the draft permit would require macroinvertebrate studies three times
per year). This particular study, conducted in March 1991, indicated that communities downstream
of the cyanide spill continued to show signs of impact several months after the spill event.
Specifically, taxa richness and number of individuals were reduced downstream of the release point.
The study also noted that macroinvertebrate and fish populations in Lynches River had rebounded
since the spill incident and that further improvement was expected (Shealy Environmental Services,
Inc., 1991).
2.1.3.2 Geology
The Brewer deposit is a crudely formed, crescent-shaped breccia body approximately 1,100 feet long
by an average of 300 feet wide. Ore grade material is encountered to depths of over 400 feet. The
grade of the deposit averages 0.040 ounces of gold per ton of ore (Brewer Gold Company, undated).
The Brewer mine property lies on the contact between the Piedmont and Coastal Plains geomorphic
provinces. The complex geology of the Brewer mine consists of cross-cutting breccia pipes occurring
near the contact of the Persimmon Fork formation and the overlying Richtex argillites of the
Piedmont. The Brewer breccia is a heterolithic breccia believed to be of multi-episodic hydrothermal
origin. Subsequent faulting and folding of this entire rock group has formed a complex ore body
(Brewer Gold Company, undated; Scheetz et al., 1991).
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Site Visit Report: Brewer Mine
The dominant minerals in the breccia are quartz, pyrite, enargite, and topaz. Accessory minerals '*
observed are cassiterite, covellite, bomite, tennantite, bismuth, sphalerite, galena, cinnabar, and gold.
The elemental signature for the breccia has been reported to be iron, manganese, copper,
molybdenum, arsenic, silver, magnesium, gold, and mercury. The primary gold mineralization is
confined to a composite hydrothermal breccia body in which several periods of brecciation and
hydrothermal fluid migration can be documented. The gold is thought to have been deposited in the
breccia by hydrothermal action (Brewer Gold Company, undated; Scheetz et al., 1991).
A local fractured system is present in the Brewer area. The area is classified by the U.S. Geological
Survey as being between a 2 and 3 seismic zone. These zones are based on the distribution of
historical, damaging earthquakes, their intensities, evidence of strain release, and distributions of
geological structures related to earthquake activity.
2.1.3.3 Hydrogeology
The depth to the uppermost aquifer (unnamed) below the Brewer facility ranges from 10 to over 100
feet. Depth to the aquifer is controlled by local topography. The aquifer is estimated to be thicker
than 100 feet. The aquifer is classified as a Class II aquifer by EPA (current and potential source of
drinking water and having other beneficial uses) and as a Class GB aquifer (similar to EPA's Class n
designation) by the State of South Carolina. This aquifer supplies water to the Brewer facility
through two main wells that reached water at about 50 feet and are about 250 to 300 feet deep. Other
uses of the aquifer were not known. Interconnections between this aquifer and others (e.g., alluvial
aquifers) were not described.
Private wells in the area (for agricultural and commercial/industrial usage) use shallow alluvial
aquifers associated with surface water bodies. The facility is located between 0.5 and 1 mile from the
nearest drinking water well and over 4 miles from the nearest public water system (which was said to
probably be in Pageland, S.C., upstream of the site). Nearby drinking water wells were sampled in
1990-1991 and the water was found to be within State standards. The Brewer facility itself uses
bottled water for drinking water.
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Site Visit Report: Brewer Mine
2.2 FACILITY OPERATIONS
The Brewer site, which is named for the original owner of the property, has had a long history of
intermittent mining operations, some of which were for minerals other than gold. It has been
reported that a miner named Fudge first worked the site, presumably for iron, before the
Revolutionary War. Gold was first discovered at the site in 1827 or 1828. Gold was first produced
at Brewer in 1828 from placer deposits using gold pans, sluice boxes, and other similar devices that
used water and gravity to separate gold from the ore (Brewer Gold Company, undated).
Hydraulic mining began at the site in 1877. In this process, jets of water under high pressure washed
loosely consolidated material into sluice boxes where gold was recovered. A five-stamp mill was
built in 1885 and enlarged to a 40-stamp mill in 1888. In 1887, an adit, the present drainage tunnel
from the bottom of the Brewer pit, was driven westward for approximately 1,000 feet into the hillside
under the main ore zone. The mine was opened from below by a raise driven up through the ore
body, connecting it to the pit above. It was these workings that were enlarged to create the old
Brewer pit. A narrow gauge track was laid in the tunnel and ore was hauled to a mill by a small
locomotive. The 40-stamp mill was located on Little Fork Creek downstream from the lower portal
of the tunnel (Brewer Gold Company, undated).
Nicor Mineral Ventures and Gold Resources, Inc. entered into a joint venture in September 1983 to
conduct exploration and a possible development program for the Brewer gold deposit. Exploration
and bulk sampling was conducted between 1984 and 1986, when the feasibility study for a modern
project was completed. Also in 1986, Costain Holdings (or a subsidiary, Costain Minerals) acquired
Nicor Mineral Ventures and formed a new company known as Westmont Mining, Inc. In March
1987, Westmont Mining began breaking ground for the processing facilities of the Brewer Gold
project. The Brewer Gold Company was formed as a subsidiary of Westmont in July 1987 to operate
the newly constructed facilities. (In 1991, Brewer Gold became a direct subsidiary of Costain when
Westmont was sold to Cambior USA.) Pre-production stripping began in June, ore crushing in July,
and the first gold was produced by the Brewer Gold Company in August 1987. Brewer Gold
currently employs approximately 104 people in its mine, crushing plant, carbon adsorption plant, on-
site laboratory, and administrative office (Brewer Gold Company, undated).
2.2.1 Mining Operations
Mining operations at the Brewer pit remove approximately 5,500 tons of ore per day (tpd) and an
additional 6,500 tpd of waste rock for a total production of 12,000 tpd. (Brewer Gold Company,
undated). Blastholes with a 6.5-inch-diameter are drilled using a crawler drill (with air compressor)
to a depth of 22 feet on a 14-foot by 14-foot pattern. Drill cores or cuttings are assayed to determine
the gold content (i.e., whether material is to be leached or considered low-grade ore or waste rock).
The holes are filled with ammonium nitrate fuel oil (ANFO) and the rock is blasted. A six cubic yard
hydraulic shovel or front-end loader then loads the broken rock into 35-ton haul trucks, which carry
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Site Visit Report: Brewer Mine
the material either to the waste rock and low-grade ore pile or to the 60,000- to 100,000-ton capacity
ore surge pile near the crushing circuit (Brewer Gold Company, undated). The facility's unlined
waste rock dump covers a 17 acre area and contains 4.5 million tons of waste rock (waste rock cutoff
= 0.017 ounces of gold per ton) as well as 550,000 tons of low-grade ore (i.e.,material with from
0.01 to 0.017 ounces of gold per ton). One section of the pile contains 20,000 to 30,000 tons of high
sulfide material, which may contain gold values higher than the cutoff grades.
2.2.2 Beneficiation Operations
Ore is fed by a 7.5-cubic-yard front-end loader from the run-of-mine ore stockpile onto a vibrating
feeder grizzly (see process flowsheet in Figure 2-2 and site map in Figure 2-3). Oversize from this
grizzly feeds a 30-inch by 42-inch primary jaw crusher, which discharges onto a belt feeding a
double-neck screen. Material less than one inch in diameter falls through the screen and oversize
material enters a secondary cone crusher where it is crushed to less than 1 inch. Ore from the
secondary crusher is screened and placed on a 10,000-ton surge pile, from which it is later reclaimed
and fed into the agglomerator. As this material is conveyed to the agglomerator, it passes over a
weightometer and under a cement silo (capacity = 125,000 pounds), where approximately six pounds
of cement per ton of ore is added (the cement serves to bind fine materials to enhance agglomeration).
The ore is then fed into a rotating agglomerator drum (10-foot-diameter by 21-foot-long), where
barren dilute sodium cyanide solution, a polymer agglomerating aid, and calcium cyanide are added to
the ore (rates per ton of ore were not obtained). The agglomerator mixes the material such that the
fine particles are either cemented into coarser particles or are rolled into porous balls. When stacked
into heaps, this enhances percolation of leaching solutions (Brewer Gold Company, undated).
Agglomerated ore is transferred to the Pad 6 heap via a series of conveyor belts and an ore stacker.
The heap is stacked to approximately 35 feet in height using a radial stacker. This heap covers about
1,100,000 square feet and has an ultimate capacity of about 2,400,000 tons of ore. Dilute cyanide
solution (200 ppm) is pumped from a double-lined Barren Pond (7-feet deep) located next to the
carbon adsorption plant to sprinklers located on top of the Pad 6 heap. The solution is generally
applied at a rate of 200 to 250 gpm. This barren solution, containing little or no gold, percolates
through the ore heaps, dissolving gold particles with which it comes in contact. The resulting
"pregnant solution" (i.e., loaded with gold) is conveyed along the impervious primary liner (60-mil
HOPE, which is underlain by twelve inches of compacted clay) and in lined ditches into a sump on
one corner of the pad. From the sump, it is pumped to the carbon plant (see site map in Figure 2-3»
(Brewer Gold Company, undated). Excess solution (e.g., from rain infiltration) flows through lined
ditches to the Pad 6 Overflow Pond, from which it can be pumped to the carbon plant. Leaching has
been completed on pads 1 through 5 and 5A and ore is currently being rinsed, as described in section
2.3.3.
2-8
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to
Open Pit
WMD
Carbon
Adsorption
Carbon
Carbon
Reactivation
Dx
a
Cyanide & Cement
Crushing
Sprinklers
Agglomeration
Leach Heap
Conveyor
Radial Stacker
[Cathodes
11
Stripping
If
Electro-
winning
Furnace
Electro
Plating
N
\\l//x
Dore Bar
Figure 2-2. Brewer Gold Company Simplified Flowsheet
(Source: Brewer Gold Company, undated)
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Site Visit Report: Brewer Mine
Solution Pondr.
1 Barren Pond
2 RIn*« Effluent Pond
(formor pregnant pond)
3 Emarganey Pond
4 Rlma Spray Pond
5 Pit Water Pond
BREWER GOLD COAPANY
GENERAL SITE AAP
DATE, oo-27-si
SCALE: I --I2M0.W
BREWER GOLD A1NE
JEFFERSON. SOUTH
SLFVEYCR. M.S/SL8
DRAW IMG No
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Sire Visit Report: Brewer Mine
In addition to cyanide leaching on Pad 6, Brewer has placed a test pile of high-sulfide ore on a
section of the pad. This material is being leached with water, which acidifies and removes copper as
it percolates through the ore. The test is intended to determine whether copper recovery is feasible
and/or if the copper content of the sulfide ore can be reduced to the point where gold recovery via
cyanide leaching is feasible. According to Brewer representatives, copper concentrations had been
reduced from 4,000 to 400 ppm (the date when leaching began was not determined).
The carbon adsorption circuit is a closed-loop countercurrent flow system consisting of five gravity
flow carbon columns. Each column is 6-foot-diameter by 8-foot-high, has a capacity of just over one
ton of carbon (roasted coconut shells), and is designed to a handle a nominal flow of 600 gallons of
solution per minute. Carbon particles are advanced through the series as gold (and other metals) is
adsorbed on the surface of the activated carbon. Pregnant solution is pumped from the sump on Pad
6 (and/or from the pad 6 overflow pond) via pipeline to the carbon circuit. After the solution has
passed through all five stages (columns) of carbon, it is discharged to the double-lined Barren Pond
(which is immediately below the circuit), refortified with cyanide, and pumped back to Pad 6 (Brewer
Gold Company, undated). Excess barren solution may be treated with hydrogen peroxide and
calcium hypochlorite (for cyanide) and flocculants (for metals) and discharged to the Sediment Pond
or used as rinsewater.
When the carbon becomes laden with gold values (up to approximately 100 pounds of gold per ton,
or 18 to 24 hours of adsorption time), it is pumped out of the column system and loaded into a
stripping vessel. In the stripping process, adsorption is reversed using a three to four percent
cyanide/strong caustic (pH = 13.5) electrolyte solution and the gold is electro won onto steel wool
cathodes (Brewer Gold Company, undated).
Typically, Brewer maintains a 4 to 1 ratio of cyanide to copper in the electrolyte solution to improve
the dore quality by binding the copper and cyanide. The electrolyte solution is changed weekly and
discharged to the facility's Barren Pond (volume was not determined). This solution typically
contains 4,000 ppm copper. Sludges are scraped out of the electrowinning cells monthly and sent off-
site to recover copper and silver values.
The stripped carbon is first washed with nitric acid to remove organic material and silica that interfere
with the reactivation process. The wash from this process is discharged to the Barren Pond and
neutralized by the high-pH barren solution (volumes of discharge from the acid wash were not
obtained). Carbon regeneration involves treatment with a hot caustic (one percent)/weak cyanide
(0.25 - 0.5 percent) solution and heating to 270° F. Regenerated carbon particles are placed back
into the carbon adsorption circuit. An average of four percent of the carbon is lost as fines during
reactivation. This material is sold to an out-of-state firm that recovers additional gold values.
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Site Visit Report: Brewer Mine
The gold-loaded steel wool is then transferred to an electrorefining cell, where gold is removed from
the steel wool by replating onto stainless steel cathode plates. Gold is then scraped from these plates
and melted in a natural gas-fired furnace at a temperature of approximately 2,000° F. to produce gold
dore bars which are shipped to refiners. The dore bars are composed of approximately 80 to 84
percent gold, copper, silver, and other trace elements. On average, the Brewer Gold Company
facility produces 100 troy ounces of dore gold per day.
Furnace slag (about one ton per year) and graphite crucibles from the facility furnace also are sold to
an out-of-state firm that recovers additional gold values from the sources. In 1990, approximately
200 troy ounces of gold were recovered from these sources and from the electrowinning sludges and
carbon fines discussed above.
2.2.3 Chemical Usage
Table 2-1 summarizes Brewer Gold Company's chemical purchases from January 1, 1991 through
September 25, 1991. As noted above, from the beginning of 1991 (actually, from October 1990)
through June 20, the facility had suspended the addition of new cyanide to leaching solutions,
although leachate (and rinsate) continued to be recirculated through the system.
Table 2-1. Brewer Gold Company Chemical Purchases, January - September 1991
Chemical
Caustic soda
Hydrated lime
Nitric acid
Calcium cyanide
Sodium cyanide
Hydrogen peroxide (50%)
Drew Chargepak 5 (floe)
Drew MP-3r Amersep. (floe)
Exxon Sureflo 7647 (antiscalant)
Quantity
45,000 pounds
180,880 gallons
1,540 gallons
476,000 pounds
88,000 pounds
784,000 pounds
2,090 gallons
1,980 gallons
5,000 gallons
Source: Brewer Gold Company, 1991g
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Site Visit Report: Brewer Mine
2.3 MATERIALS AND WASTE MANAGEMENT
For purposes of this discussion, materials management practices at the Brewer Gold Company mine
are divided into process and waste management units. Process units are those that contain materials
that are not considered wastes until after facility closure. Examples of process units (and process
materials) are heap leach pads (and spent ore) and the open pit (and mine water in the pit during
operation). Waste units are those that contain materials that will undergo no further beneficiation.
Examples of these include waste rock piles and wastewater holding ponds.
The following section describes waste and material management at the Brewer Gold Company site.
Also included is a discussion of current closure and reclamation plans for each mine component.
Actual closure practices and requirements will be determined by the State as the end of the mine's
active life approaches.
2.3.1 Mine Pit and Water
The total disturbance of the Brewer pit is approximately 33 acres. From the highest point of 580 feet
above sea level, the pit has now reached an elevation of about 400 feet. In addition, Brewer was
considering (at the time of the site visit) mining an off-site satellite pit beginning in February 1992,
pending the appropriate permits from DHEC and the Land Resources Commission. Ore will be
trucked to the present site for beneficiation and processing (the pit is located in adjacent Lancaster
County near the town of Kershaw). Upon cessation of operations at the Brewer site, pit dewatering
will cease and the water table will be allowed to return to its near-natural level, which will form a
small lake in the lower extremities of the pit. The natural water table is approximately the level to
which mining has currently reached, so continual dewatering has not been necessary to date.
According to Brewer representatives, the pit will be excavated to some additional depth (estimated to
be about 100 feet, to the 300 foot level), so there will be a "lake" in the pit after closure. As more
sulfide-bearing minerals are exposed to an oxidizing environment as the pit deepens, acid generation
may occur.
Upon closure, reclamation of the pit will involve stabilizing the slopes by dozing and blasting areas
determined to be unstable (Brewer Gold Company, 1990b). According to the Land Resources
Commission, sloping to a 3H:1V gradient will be required in the upper portions of the pit wall where
saprolite and soil exist. After sloping is completed, vegetation will be established. As noted, the pu
will contain water upon closure. Upon final reclamation, this water will be required to meet
applicable water quality standards for lakes, as promulgated by DHEC. Due to the acid generation
potential in the lower portions of the Brewer pit, Brewer has proposed that process solutions may be
diverted directly to the pit. This would decrease the time necessary to fill the pit with water, which
would minimize the time that sulfide minerals in the pit would be exposed to an oxidizing
environment. In addition, because the process solution will have an elevated pH, it could act as a
buffering agent for any acid that may have formed in the pit.
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Site Visit Report: Brewer Mine
Pit water includes any ground water infiltrating into the pit, precipitation directly entering the pit, and
any site runoff that flows into the pit. These waters currently drain out of the pit through an old adit
previously used in underground mining operations at the site, which also drains underground
workings. A.S.C.I. (1990) referred to pH values of 2 and relatively high copper concentrations in
adit discharges, but further information on adit or pit water quality was not available.
/
The facility's NPDES permit, as modified in late 1990, requires the installation and use of a treatment
system for pit water prior to its discharge via internal outfall to the Sediment Pond (see discussion of
Construction Permits 16,727 and 17,170 in section 2.4 below). With this treatment system, pit water
will be pumped from the pit to a double-lined 3.5 million gallon pond near the carbon circuit and
treated with lime and flocculants to adjust pH and reduce metals (particularly copper). From there,
water will be used to supply the rinse circuit or discharged to the Sediment Pond prior to discharge
via existing NPDES outfall 001. Brewer estimates that discharge to the Sediment Pond will average
between 75 and 100 gpm. Brewer representatives indicated during the site visit that the treatment
system had been completed and was awaiting State approval before being placed in service; according
to DHEC, the system obtained an operating permit on February 14, 1992. Brewer representatives
also indicated that the old adit, through which pit water was previously discharged, would be plugged
at the upstream end (i.e., at the pit). Discussions between Brewer and the State were ongoing
concerning the remaining ground-water drainage from the old adit once the upstream end is plugged.
2.3.2 Waste Rock Pile
The stripping ratio of the Brewer Mine is approximately 1.2:1. To date, about 4.5 million tons of
waste rock have been disposed in an unlined multi-lift pile covering an area of 17 acres. Site
preparation for the waste pile consisted of compacting native soil. Runoff from the pile, which is
located immediately south of and adjacent to the Brewer pit, drains into the facility's Sediment Pond
and the mine pit.
Waste rock (cutoff = 0.017 ounces of gold per ton of rock) at the Brewer facility is typically
alumina/silica rock containing quartz and one to three percent pyrite. Low-grade ore (0.01 to 0.017
ounces of gold per ton of rock) is placed in a designated area of the pile. There are currently
550,000 tons of low-grade set-aside ore in the waste rock pile. In addition, high sulfide material is
segregated in a discrete section of the waste rock pile for potential future use or disposal (oxide and
mixed materials have very little buffering capacity, so mixed disposal was determined to have little
benefit in mitigating acid potential [A.S.C.I., 1990]). To date, only 20,000 to 30,000 tons of high
sulfide material have been removed from the mine, although as the pit extends downward, the
percentage of sulfide material may increase. Drainage from this area of the pile flows into the
Brewer pit.
Samples of waste rock taken in 1988 (no information was available on locations or types of samples)
showed total sulfur values ranging from less than one percent to over 17 percent. Acid generation
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Site Visit Report: Brewer Mine
potential of waste rock, based on humidity cell testing, is described as "moderate" (no definition of
"moderate" was provided) (A.S.C.I., 1990).
As described in section 2.4.1.1, Brewer monitors ground water hi three wells near the waste rock pile
and Sediment Pond.
Closure activities are expected to require special grading and site preparation. Specifically, to
minimize erosive forces of runoff, grading of the top portion of the waste will be towards the
northeast and away from the side slopes, thus limiting overland flows down the slopes to incidental
precipitation. Current plans are to direct the runoff into the mine pit for additional sediment control.
Other reclamation may include the installation of an impermeable cap for acid control and a layer of
non-toxic material and/or topsoil to support vegetation and maintain the integrity of the cap (Brewer
Gold Company, 1990b).
Closure activities for the high sulfide section of the pile are expected to involve grading and in-place
encapsulation with either a compacted clay layer or a synthetic layer to restrict water movement
through the material to limit oxidation and transport of acid. Other acid control technologies, such as
active treatment of sulfide materials with lime or the addition of bacterial inhibitors, are also being
evaluated. (Brewer Gold Company, 1990b)
The Land Resources Commission emphasizes that the present closure plan (Brewer Gold Company,
1990b) is preliminary and was based on partial data in order to develop conceptual plans for closure.
A final closure plan will be required, with more information derived from operational data and
additional test data, and will specify proper closure requirements for the waste rock dump, leach
pad(s), acid generation potential, pit water chemistry, and plant process facilities.
2.3.3 Leach Pads and Spent Ore
There are seven heap leach pads, which cover about 53 acres, at the Brewer site. Currently, only
Pad 6 is being actively leached. Pads 1 through 5 and 5A are being rinsed to reduce cyanide levels
and pH. Pads 1 through 5 and 5A contain about 2.8 million tons of spent ore.
Pads 1 through 4 are contiguous, each measuring approximately 170,000 square feet. They were
constructed with a 40-mil HOPE primary liner over 12 inches of compacted "silty clayey coljuvial
material;" there is no leak detection system between or below the liners (Steffen Robertson & Kirsten,
undated). These pads were part of the original facility construction. Pad 5, constructed in 1988, was
initially intended to be an on-off leach pad of 425,000 square feet with an asphalt base; the use of
asphalt was intended to minimize the risk of liner degradation during ore movement. The on-off plan
was subsequently abandoned (in 1989) and spent ore remains on the pad during rinsing until its
ultimate fate at closure is determined. Pad 5 asphalt has a permeability of 2x10"* to IxlO"7, with a
IxlO"9 rubber membrane in the center of the asphalt. The asphalt overlies 12 inches of crushed stone
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Site Visit Report: Brewer Mine
with a fabric filter and a french drain leak detection system around the downgradient perimeter.
There also is a leak detection sump. Pad 5A covers a 60,000 square foot area between Pads 1-4 and
Pad 5. Except for the portions of Pad 5A located on the asphalt apron of Pad 5, Pad 5A has a 60-rnil
HOPE liner over compacted clay; only the asphalt portion of Pad 5A has leak detection capability.
Active cyanide leaching was concluded on Pads 1 through S and SA prior to 1990, and full-scale
rinsing began in mid-1990. Although South Carolina law does not require rinsing to a specific
cyanide concentration (levels must be "to the satisfaction of the State"), the State requires Brewer to
rinse the spent ore on the heap leach pads until cyanide and metal concentrations in rinsate reach
acceptable levels (either NPDES water quality standards or drinking water standards, depending on
the ultimate fate of the spent ore). According to DHEC, when the free cyanide concentration reaches
0.2 ppm, it will trigger monthly rinsate testing for NPDES parameters and for free, total, and weak
acid dissociable cyanide. The State considers that this will demonstrate that adequate rinsing has been
conducted as well as aid in determining specific closure methods for the spent heaps. According to
the Land Resources Commission, heaps closed and reclaimed in-place (as these may be, since the
decision had not been made) will have to demonstrate that runoff will not adversely affect aquatic life
in neighboring streams.
Brewer Gold Company received a permit to modify its calcium hypochlorite treatment system by
adding hydrogen peroxide treatment in May 1990 (DHEC, 1990d). The system is intended to treat
rinsate as well as other cyanide-bearing waters prior to re-use in rinsing or discharge to the Sediment
Pond. (The extent to which the system had been used for rinsate by early 1991 was not clear.
Brewer's "Status Report and Schedule for Rinsing" (Brewer Gold Company, 1991e] indicates at one
point that rinsing through June 1991 involved "no treatment whatsoever." At another point, the
report indicates that the hydrogen peroxide solution treatment system "has been successfully utilized
for the production of clean rinse solution since its installation.") In any event, the treatment system
previously involved the use of calcium hypochlorite for cyanide destruction. The new system
involves the addition of hydrogen peroxide to the rinse solution. A flocculent may also be added to
the treated solution prior to settling (Steffen Robertson and Kirsten, 1990). Rinsate is generally
applied to the heaps at 600 gpm. Brewer estimated in March 1991 that rinsing of Pads 1 through 5
and 5A would take an additional 661 days for cyanide concentrations to reach the levels required; as
of March 1991, cyanide concentrations had decreased from about 300 ppm to 10 ppm or less (Brewer
Gold Company, 1991e).
Rinsate from Pad 5 collects in a sump on the pad and is either pumped to the treatment plant or re-
applied without treatment. Rinsate from pads 1 through 4 collects in a common sump or drains to a
double-lined rinse effluent pond (the former pregnant pond for pads 1 through 4). After peroxide
treatment (and fiocculation), the solution is stored in a double-lined rinse settling/reclaim pond, from
2-16
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Site Visit Report: Brewer Mine
which it is recirculated to the pads under rinse or used as cyanide leachate makeup and applied to Pad
6. Excess rinsate is treated and discharged to the Sediment Pond. (Steffen Robertson and Kirsten,
1990; EPA, 1991)
Pad 6 covers an area of between 1 and 1.2 million square feet and has an ultimate ore capacity of
about 2.4 million tons of agglomerated ore. Most of Pad 6 now contains a single 35-foot lift of ore,
and only a small portion of liner remained uncovered at the tune of the site visit (a larger area of
liner was exposed during heavy rains hi October 1990, which contributed to water management
problems at that time). A second 35-foot lift was expected to be added to Pad 6 beginning in late
1991 (EPA, 1991). Pregnant solution is collected in a sump at one corner of Pad 6 before being
pumped to the carbon adsorption circuit. Excess solution from infiltration of rainfall and runoff drain
via lined ditches that surround the heap to the Pad 6 overflow pond (see section 2.3.5 below) prior to
being pumped to the carbon circuit.
As described in section 2.4.1.1, Brewer monitors ground water in four wells near Pad 6. Results of
monitoring are presented in that section.
When cyanide leaching is completed, Pad 6 also will be rinsed to reduce cyanide and metal
concentrations. Brewer estimates that one year of rinsing at 1,600 gpm, beginning in 1993 or 1994,
will be sufficient to achieve cyanide levels below 0.2 ppm (Brewer Gold Company, 1991e). No
information was available on the ultimate fate of the high sulfide ore being water-leached on a small
area of Pad 6 at the time of the site visit.
Samples of spent ore were tested for Extraction Procedure (EP) Toxicity and were found not to
demonstrate this hazardous characteristic (sources and numbers of samples, dates, arid other
information on this sampling were not available). Tests in 1988 for acid production potential/acid
neutralization potential (in tons of CaCO3/kTon) indicated that the "acid generation potential is high."
It also was not known if lime that is added to ore for pH control will prevent long-term acid
generation (A.S.C.I., 1990).
Once rinsing is completed on the various pads, Brewer will have several options for managing the
spent ore, depending on the quality of rinsate and solid sample tests. In general, the option ultimately
selected by Brewer and approved by the State will depend on the success of rinsing in reducing pH
and concentrations of cyanide and copper and other metals and on the quality of rinsate. Options
include:
If concentrations in rinsate and solid samples meet NPDES water quality-based limits,
spent ore may be off-loaded, subject to erosion and sediment control requirements of the
Land Resources Commission
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Site Visit Report: Brewer Mine
If rinsate meets drinking water standards but .not water quality-based limits, spent ore may
be off-loaded to a pit with no surface water discharge
If neither drinking water standards nor water quality-based limits are met, the material may
have to be encapsulated to prevent discharge to either surface or ground water and would
be subject to applicable requirements of DHEC's Bureau of Solid and Hazardous Waste.
Heap reclamation activities will involve grading of side slopes to an overall slope of 3H:1V and
revegetating, with added provisions for runoff control and stabilization, as heap slumping has been a
problem at the facility in the past (Brewer Gold Company, 1990b). Problems with slumping and
excess sediment in rinse ponds had led to a temporary suspension of rinsing on pads 1 through 4;
these pads were being regraded and reshaped to a slope of 3H: IV and revegetated before rinsing was
continued (Brewer Gold Company, 1991f). This is intended to stabilize the slopes and enhance
percolation. During the site visit, it was observed that some slopes of pads 1 through 4 had well-
established grasses.
Brewer has proposed that at closure, intermediate bench slopes be graded to control surface runoff
and erosion. All final slopes will be covered with topsoil, fertilized, and revegetated. In addition,
the leachate collection pond will be maintained to collect subsequent leachate from heaps due to
incidental precipitation. The pond will be graded to provide gravity flow to the treatment plant or
provided with a pumping system. The treatment plant will be operated and the leachate monitored
until such time as water quality of the leachate allows other options to be used (Brewer Gold
Company, 1990b).
2.3.4 Sediment Pond
The Brewer operation is intended to be a closed system. However, the facility is periodically faced
with excess water resulting from precipitation. This water, which can be runoff or excess process
water, is treated in a cyanide destruct unit (as noted above, originally a calcium hypochlorite system
and now involving hydrogen peroxide treatment and flocculation as well) before being directed to the
Sediment Pond. From the Sediment Pond, water can re-enter the process or rinsing circuits or be
discharged via NPDES permit.
The Sediment Pond dam is about 55 feet high with a crest elevation of 420 feet above sea level. The
upstream and downstream faces are sloped at 2.5:1 and 3:1, respectively. A 15-foot wide bench, at
an elevation of approximately 388 feet, was included in the downstream face of the dam. The dam i»
a zoned earthen structure constructed widi a clay core set into a shallow trench, compacted silty
gravelly shells, and chimney and blanket drains. An emergency spillway was cut through bedrock to
the east of the left abutment (Steffen Robertson & Kirsten, 1987). The pond was permitted at
846,000 gallons (DHEC, 1987a) and is unlined.
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Site Visit Report: Brewer Mine
At the pond, lime is used to adjust pH and flocculants are added to reduce the levels of metals in the
water. When necessary, treated water is discharged via a pipeline to a permitted outfall (designated
outfall 001 in the facility's NPDES permit). Discharge is not continuous; treatment and batch
discharges occur when excess process water and storm water accumulate. Approximately 32 million
gallons of excess water were said to be treated and discharged from the Brewer Mine annually (EPA,
1991).
Table 2-2 presents flows to (outfall 002) the Sediment Pond and from (outfall 001) and concentrations
of selected parameters from March through August 1991. Data were taken from Brewer's monthly
NPDES discharge monitoring reports (Brewer Gold Company, 1991c).
Table 2-2. Concentrations of Selected Parameters in Discharges from Outfalls 001 and 0021
(all concentrations in milligrams per liter except pH)
Parameter
Month (1991)
March
April
May
June
July
August
Outfall 001: Sediment Pond discharge to Little Fork Creek
Total Flow (106
gallons)
pH (s.u.)
Cyanide
Copper
Mercury
13.199
8.52
0.120
0.048
< 0.0002
No
discharge
13.237
S.92
0.134
0.084
< 0.0002
No
discharge
13.733
8.42
0.035
0.1832
< 0.0002
4.331
8.82
0.107
0.026
0.00036
Outfall 002: Cyanide Destruct Unit discharge to Sediment Pond
Total flow (106
gallons)
pH (s.u.)
Cyanide
Copper
Mercury
4.041
10.2
6.13
132.
0.0011
4.256
10.72
7.68
148.
0.0011
1.206
10.35
2.4
36.9
0.0103
5.400
11.05
4.35
40.
0.006
4.134
10.58
4.28
47.3
0.0144
2.160
11.42
7.21 ,
35.5
0.0009
1. See Table 4 for effluent limits in NPDES Permit SC0040657 on outfall 001.
2. Value shown is highest value reported (n = 2).
Source: Brewer Gold Company, 199 Ic.
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Site Visit Report: Brewer Mine
As noted previously, Brewer's draft revised NPDES permit calls for effluent from the pit water
treatment system to be discharged to the Sediment Pond through internal outfall 002 prior to its
discharge through outfall 001. According to Brewer representatives, this will begin upon State
approval of the system (which, according to the State, was obtained hi early 1992).
As described hi section 2.4.1.1, Brewer monitors ground water hi three wells near the waste rock pile
and Sediment Pond. Results of monitoring are presented hi that section.
Upon closure, remaining solutions will be treated and discharged as required in the facility's NPDES
permit. Treatment will likely involve hydrogen peroxide cyanide destruction and flocculation to
further decrease metals (particularly copper). The pond itself will remain after closure.
At the tune of the site visit, Brewer Gold Mining Company was searching for a market for the
process sludge that may be recovered, which was expected to be rich hi copper. If a market could
not be found, the sludge was to be geochemically immobilized with cement and encapsulated in place
or moved to an alternative site for disposal (Brewer Gold Company, 199If). During the site visit,
Brewer representatives indicated that less than an inch of sludge had accumulated to date. No
information was available on sludge characteristics.
2.3.5 Pad 6 Overflow Pond
In December 1989, Brewer Gold Company obtained a permit to construct what is now Heap Leach
Pad 6 (DHEC, 1989b). This construction permit included provisions for an overflow pond associated
with the pad. The pond had a capacity of 17.5 million gallons, and was double-lined, with a leak
detection sump. The pond received excess solution from Pad 6. The pond was located in a natural
drainageway just below Pad 6.
The original dam failed in October 1990, as described hi more detail below. Following the failure,
Brewer received new construction permits numbers 17,027 and 17,052 (DHEC, 1991b and 1991c; see
Table 2-5) for pond redesign and reconstruction, respectively. The new pond's dam is an earthfill
structure with a seal zone on the upstream face. A chimney drain connects to a horizontal toe drain.
Permit 17,052 also required the construction of three movement monuments as well as two standpipe
piezometers and three vibrating wire piezometers.
The pond itself has a 18.9 million gallon capacity and is lined (clay seal overlain by 60-mil HOPE
primary and 40-mil HOPE secondary liners) with a geonet leak detection/recovery system between the
HOPE liners. Underneath the liners is a network of drains (clean gravel with slotted pipe) to collect
ground water. There is also a lined (60-mil HOPE) emergency overflow ditch that leads to an 18,000
gallon reinforced concrete outlet sump just below the dam, which also receives underdrain discharge
and any water collected in the leak detection system.
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Sire Visit Report: Brewer Mine
As described in section 2.4.1.1, Brewer monitors ground water in one well near the pad 6 overflow >
pond as well as from the underdrains beneath the pond-(the pond also has a leak detection sump that
is monitored). Results of monitoring are presented in that section.
2.3.6 Solution Ponds
In addition to the Sediment Pond and Pad 6 Overflow Pond described above, the Brewer Gold facility
currently operates a number of other solution ponds, all at the southern foot of Pads 1-4 near the
carbon plant (see Figure 2-3). These ponds are described below.
Barren Pond. This 900,000 gallon ppnd (DHEC, 1987b), part of the original construction, is about
seven feet deep with 2:1 side slopes. Like the rinse effluent pond described below, it was constructed
with 40-mil HDPE and 20-mil PVC liners over 12 inches of compacted silty-clayey material. A leak
detection system of polyethylene Gundnet and geofabric was installed between the synthetic liners
(Steffen Robertson & Kirsten, 1987). Barren solution enters this pond directly from the carbon
circuit. Because it is located immediately below Pads 1 through 4 and receives runoff from heaps and
from the carbon plant, it also has received sediment from erosion (Brewer Gold Company, 1991f).
Barren solution, according to a number of spill and leak reports, contains sodium cyanide at
concentrations of 600 ppm or more. Solution from this pond is typically made-up with additional
cyanide and re-applied to Pad 6, but may be treated and then discharged to the Sediment Pond or
used as rinsewater.
Rinse Effluent Pond. This pond, the original pregnant pond for Pads 1 through 4, was permitted at
1,999,000 gallons (DHEC, 1987b). This pond is about seven feet deep with 2:1 side slopes. Like
the barren pond, it was constructed with 40-mil HDPE and 20-mil PVC liners over 12 inches of
compacted silty-clayey material. A leak detection system of polyethylene Gundnet and geofabric was
installed between the synthetic liners (Steffen Robertson & Kirsten, 1987). It receives rinsate directly
from Pads 1 through 4. As noted in section 2.3.3, problems with sedimentation in this pond and
fines in the rinse treatment circuit had led, at the time of the site visit, to a cessation of rinsing of
Pads 1 through 4 while the pads were being regraded, resloped, and revegetated. During the site
visit, it was noted that significant amounts of sediment had accumulated in this pond. According to
Brewer, the sludge/sediment in this pond is coarser than in other ponds (up to 1.5 inches in
diameter). Should removal of the sediment/sludge be necessary, it would be placed back on one of
the pads being rinsed (Brewer Gold Company, 1991f). Analytical data on sediment quality were not
available.
Rinse Reclaim Pond (or Rinse Spray Pond). This pond (formerly the Rinse Pond) was also part of
the original facility. It was apparently permitted at 8,900 gallons [DHEC, 1987b] but appeared
during the site visit to have a capacity of several hundred thousand gallons. It is lined with 40-mil
HDPE and 20-mil PVC over 12 inches of compacted silty-clayey material. A leak detection system
of polyethylene Gundnet and geofabric was installed between the synthetic liners (Steffen Robertson &
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Sire Visit Report: Brewer Mine
Kirsten, 1987). The pond receives treated water from the cyanide destruct unit prior to re-application
to pads under rinse. As of January 1991, it contained about 4.1 inches of sludge with a 23 percent
solids content. Sludges are metal hydroxides, primarily copper hydroxide: the sludge is
approximately 15 percent copper (Brewer Gold Company, 1991d).
Emergency Pond (or Effluent Settling Pond). This 3,000,000 gallon pond receives overflow from the
rinse effluent pond (the former pregnant pond) and may also be used to store other excess waters.
Details on its construction were not available, although Brewer indicated it is double-lined with a leak
detection system. The only information on cyanide concentrations came from an incident in January
1989, when there was significant leakage into the pond's french drain. At that time, sodium cyanide
concentrations averaged about 300 ppm, and pH averaged about 10 (Brewer Gold Company, 1989).
Pit Water Treatment Pond. This 3,500,000 gallon pond was constructed in 1990-1991. The original
construction permit (issued October 29, 1990) authorized a 1,000,000 gallon pond and a pit water
treatment system. With the permit in place, a lined pond was constructed after the failure of the Pad
6 Overflow Pond (see sections 2.3.5 and 2.4.4.14) to provide emergency storage for solution from
Pad 6 and storm water. This pond was constructed with a 3,500,000 gallon capacity, a primary liner
of 60-mil HDPE, a secondary liner of 20-mil VLDPE over one foot of compacted clay, and a leak
detection sump between the liners. The pond was to receive process wastewater until the Pad 6
overflow pond was rebuilt. This pond, with increased capacity and a revised pit water treatment
system, was reissued a construction permit, which superseded the original permit, on October 29,
1991. (Because this permit was in preparation at the time of the site visit and was issued shortly
thereafter, it was not examined by the site visit team; rather, it was described by DHEC in comments
on a preliminary draft of this report).
The pond will receive water from the pit water treatment system once that system is placed in
operation (as noted previously, the system received its operating permit in early 1992). Water from
the pond will feed the rinse circuit or be discharged to the Sediment Pond. Sludges are expected to
contain high levels of copper and iron hydroxides (over 15 percent copper) and Brewer anticipates
finding a market for the sludges before closure (Brewer Gold Company, 1991f).
Carbon Fines Pond. This small pond is used to settle carbon fines. Details on the pond were not
obtained. As noted previously, fines are periodically removed for precious metals recovery.
As described in section 2.4.1.1, Brewer monitors ground water in four wells near the solution ponds.
Results of monitoring are presented in that section.
A number of options for sludge disposal at or before closure are being considered. Brewer will
search, for markets for metal-laden sediments. Alternatively, sludges may be enveloped in the plastic
liners and heat-sealed or they may be geochemically immobilized (by fixation in cement). Brewer's
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Site Visit Report: Brewer Mine
tentative reclamation plans for ponds included folding and burying of liners and backfilling or
breaching of pond areas. (Brewer Gold Company, 1990b and 1991d) According to the Land
Resources Commission, Brewer will be required to remove all pond liners at closure to allow for
proper disposal at a licensed waste disposal site.
2.3.7 Other Wastes and Materials
Table 2-3 lists other wastes and materials generated at the Brewer Gold Company facility and the
means by which they are managed.
Table 2-3. Other Materials and Management Practices, Brewer Gold Company
Waste
Spent Carbon
Sanitary Sewage
Solid Waste
Used Oils
Laboratory Wastes
Spent Solvents
Management Practice
Sent off-site for additional gold recovery by an outside firm
(calculated to be approximately 1,500 tons per year)
Managed in an on-site leach field
Local "trash" collection pickup
Stored in on-site tanks and sent off-site via purchaser or recycler
(approximately 1,500 gallons per month, but varies with facility
production rates)
Liquid lab wastes are added to the process water circuit at the
rinse or barren stage; solid lab wastes (e.g., broken glass) are
disposed with solid waste. Management of cuttings and drill
cores was not determined.
Safety-Kleen supplies and picks up solvents used for metal
cleaning (quantities not determined)
2-23
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Site Visit Report: Brewer Mine
2.4 REGULATORY REQUIREMENTS AND COMPLIANCE
A number of State agencies are responsible for regulating various aspects of Brewer Gold's
operations. These agencies, permits they have issued to Brewer, and the permits' major
requirements, are described below.
2.4.1 South Carolina Department of Health and Environmental Control
2.4.1.1 Bureau of Water Pollution Control
The Bureau of Water Pollution Control (WPC) within DHEC is charged with protecting surface and
ground waters of the State. With respect to the Brewer facility, the Bureau's authority stems from the
Clean Water Act (CWA) and the South Carolina Pollution Control Act (PCA). Applicable regulations
include: SC Regulation 61-9 (NPDES Permits), SC Regulation 61^68 (Preparation and Submission of
Engineering Reports); SC Regulation 61-68, -69 (Water Classification and Standards); and SC
Regulation 61-71 (Well Standards and Regulations).
The Bureau's authority over the facility extends as long as there are potential impacts to surrounding
waters, from construction through post-closure. The Bureau's program is implemented through
permitting systems, violations of which can result in the issuance of consent orders or administrative
orders as well as civil and criminal actions. The Bureau has issued an NPDES permit to Brewer
Gold Company for surface water discharges, as well as construction permits for facility components,
which include ground-water monitoring requirements. These permits and their major requirements
are discussed below.
NPDES Permit SC0040657 (DHEC, 1986 and 1990c). Brewer Gold Company's NPDES permit was
originally issued in November 1986, with an expiration date in November 1991. Modifications to the
permit were to be effective December 1, 1990; the expiration date was to be November 30, 1995. As
noted below, however, Brewer adjudicated certain provisions of the modified permit, which stayed
their effectiveness. According to DHEC, a revised draft permit was in its final stages of revision at
the time of the site visit and was expected to be issued in the near future.
The original (and the new draft) permit authorizes a discharge of process wastewater and stormwater
from the Sediment Pond to Little Fork Creek. In the original permit, the volume of discharge
permitted is dependent on the differential between the annual precipitation falling on the facility and
the drainage area contributing to surface runoff to the treatment facility, and annual evaporation. To
this end, Brewer is required to report, on an annual basis, the total amount of effluent discharged, the
total volume of precipitation, and the evaporation for the preceding year (the capacity of the treatment
system is about 600 gpm, which effectively limits discharges to that level). Table 2-4 shows effluent
limits in the original permit. The revised draft NPDES permit is based on a controlled discharge of
poundage per million gallons of streamflow in Little Fork Creek (i.e., so many pounds of a pollutant
2-24
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Site Visit Report: Brewer Mine
Table 2-4. Effluent Limits1 in Brewer Gold Company NPDES Permit SC0040657
(units in milligrams per liter except pH)
Parameter1 :
TSS
Oil and Grease
Total Residual
Chlorine
Cyanide
Arsenic
Copper
Lead
Mercury
Zinc
.Cadmium
Silver
Molybdenum
Aluminum
PH (s.u.)
; NPDES Permit Effective
December 1, 1986
Dally
Average
Dairy
Maximum
, mg/L
20
10
0.352
0.166
6.0
0.150
0.050
0.00038
0.75
0.021
0.038
22
-
30
15
0.608
0.332
11.5
0.300
0.084
0.00076
1.5
0.042
0.076
44
-
6.0 - 9.0
Revised Draft Permit
(to be Issued m near future)
Monthly
Average
Daily
Maximum
lbs/MG*
-
-
0.835
0.08353
0.417
0.0835
0.417
0.00167
0.392
0.0835
0.25
2.09
0.726
-
-
1.67
0.1673
0.835
0.167
0.835
0.00334
0.784
0.167
0.5
4.18
6.26
6.0 to 9.0
Monthly
Average
Daily
Maximum
mg/L
20
10
0.5
0.65J
-
0.15
0.3
0.001
0.75
0.05
-
-
30
15
1.0 .
1.23
-
0.30
0.6
0.002
1.5
0.10
.
-
-
6.0 to 9.0
1 Although the 1986 permit did not speciiy species for parameters. Discharge Monitoring Reports did require totals. Limits
in the revised draft permit are on totals (e.g., total cyanide, total copper).
2 Monitoring requirements specify grab samples taken once per discharge, up to two samples per month. The revised draft
permit requires weekly samples.
3 Brewer has petitioned to have cyanide limits reflect weak acid dissociable cyanide. Limits on total cyanide were stayed
pending resolution. The revised draft permit requires analysis for total cyanide.
4 MG = million gallons streamflow in Little Fork Creek.
Sources: DHEC, 1986 and 1990c.
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Site Visit Report: Brewer Mine
per million gallons of streamflow). In addition, monthly discharge monitoring reports are submitted
4o DHEC. These reports include flow measurements as well as effluent monitoring data.
The revised draft permit also was to establish a second permitted NPDES outfall (002). This is an
lv
internal outfall located at the point where plant process water is discharged to the Sediment Pond.
Under the permit, the facility is required to monitor outfall 002 and report monthly on levels of the
following parameters: Flow, TSS, Copper (Total), Lead (Total), Mercury (Total), Zinc (Total),
Cadmium (Total), Cyanide (Total), pH, floating solids, visible foams, and visible sheen (DHEC,
1990c).
Other major alterations in the revised draft permit include changes in effluent limits, as shown in
Table 2-4. In addition, Brewer was required to install a high rate diffuser (in lieu of acute toxicity
testing of effluent) and conduct macroinvertebrate studies in Little Fork Creek three times per year.
Brewer must record streamflow, effluent flow, and the ratio during discharges to verify compliance
(DHEC, 1990c). The facility has a U.S. Geological Survey gaging station in Little Fork Creek to
make these measurements.
Brewer petitioned DHEC to reconsider two of the requirements in the 1990 modifications to the
NPDES permit: the dilution factor, which DHEC had established at less than 75 to I (i.e., the
instantaneous ratio of streamflow to effluent discharge would have had to be 75 or greater-Brewer
requested that it be lower during periods after heavy precipitation conditions); and the discharge limits
for cyanide, which were based on total cyanide (Brewer requested that it be based on weak acid
dissociable cyanide). As noted above, these provisions of the modified permit were stayed pending
resolution; because the dilution factor affected essentially the entire permit, the existing (1986) permit
was effective pending resolution of the revised draft permit (DHEC, 1990c; Haynsworth, Baldwin,
Johnson and Greaves, 1990; Brewer Gold Company, 1990i and 1991d). According to DHEC, the
dilution factor issue has been addressed in the revised draft NPDES permit by changing to a basis of
poundage per million gallons of streamflow in Little Fork Creek and the method for analysis for
cyanide has remained total cyanide.
If Brewer's monthly discharge monitoring reports show that effluent limits in the NPDES permit have
been exceeded by a small amount, DHEC requires the facility to explain the excursion and the
reasons (e.g., laboratory error, operator error). If there are significant violations or continuing
violations that are not brought under control, DHEC may require sampling and possibly take
enforcement actions.
Construction Permits. In addition to the NPDES permit, the Bureau of Water Pollution Control has
issued 11 construction permits to Brewer Gold Company. Table 2-5 below lists these permits, the
activity or facility component/operation covered, and major permit requirements.
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Site Visit Report: Brewer Mine
Table 2-5. Construction Permits Issued to Brewer Gold Company
Permit
Number
Issue
Date
Nature of Permit
Major ReguJrementg
13,135
4/87
Sediment Pond
(846,000 gallon capacity)
N/A
13,172
5/87
Original Facilities
(600 gpm hypochlorite cyanide treatment system,
54,000 gallon treated water holding pond, and
recirculated process system: 1,999,000 gallon
pregnant pond, 901,000 gallon barren pond, 8,900
gallon rinse water pond, four 180,000 feet leach
pads and associated piping)
Submit BMP plan, maintain O&M manual
onsite
Monitor cyanide wastewater treatment
system once per discharge for 13 parameters'
Monitor leak detection sumps of barren,
carbon, and pregnant ponds for liquid, pH,
and total cyanide
Pipe underdrain discharges from closed-out
leach pads to Sediment Pond
Sample groundwater monitoring wells
quarterly for 32 parameters11
Sample emergency spillway discharge, if
any, from rinse water pond for 13
parameters*
Submit QA plan for installation of liner
system
Allow no overspray of cyanide process
solution out of heap leach containment area
Submit plan for approval prior to rinsing
heap leach pad for closure
14,217
5/88
Pad5
(Add 780 feet by 545 feet on-off asphalt-lined
leach pad with French drain leak detection
system, two 1,000 gallon two stage solution
sumps, leak detection sump, 3.6 million gallon
pregnant pond, associated piping and
appurtenances).
Monitor pregnant pond leak detection sump
for liquid, pH, and total cyanide
Obtain DHEC approval before placing spent
ore from Pad 5 on Pads 1-4
Submit closure plan for pad at least six
months prior to end of operations
Install groundwater monitoring well near
pregnant pond
Monitor leak detection sumps of barren,
carbon, pregnant, rinse, and emergency
ponds weekly for the life of the project for
presence of liquid, pH, and total cyanide
Including pH, total cyanide, cyanide, thiocyanate, total residual chlorine, copper, zinc, lead, mercury, cadmium, TSS, flow, and
ammonia.
"Including pH, conductivity, hardness (as CaCO,), alkalinity, carbon, TKN, ammonia, nitrite, nitrate, phosphorus, chloride,
turbidity, mercury, potassium, manganese, calcium, iron, sodium, magnesium, aluminum, barium, cadmium, chromium, copper,
silver, zinc, arsenic, lead, selenium, TDS, sulfate, and total cyanide.
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Site Visit Report: Brewer Mine
Table 2-5. Construction Permits Issued to Brewer Gold Company (continued)
Permit
Number
Date
Nature of Permit
Major Requirements
15,697
9/89
PadSA
(Post-construction approval for 60,000 square
feet leach pad and modification of Pad 5 from a
reusable leach pad to a dedicated leach pad).
Submit QA/QC plan for construction and
installation of Pad SA
Submit closure plan for Pad SA within 6
months of permit issuance
Allow no overspray of cyanide process
solution out of heap containment area
15,699
9/89
Sediment Pond Flocculation System
(Flocculation system for the sediment pond: one
1,000 gpm (60 hp) pump, piping, metering
pumps, 1,250 gallon steel mixing tank with
mixer).
Water pumped from pond for use in dust
control must comply with NPDES permit
effluent limits
Submit closure plan for pond within six
months of permit issuance
15,869
12/89
Pad 6
(1,100,000 square foot heap leach pad with leak
detection sump and 10,000 gallon collection sump
and associated pumps and piping, and 17.5
million gallon pond and leak detection sump and
associated pumps and piping).
Update BMP plan
Monitor leak detection sumps of Pad 6 and
Pad 6 overflow weekly for the life of the
project for liquid, pH, and total cyanide
Sample groundwater monitoring wells and
underdrain quarterly for 32 parameters2
Submit "worst case" contingency closure
plan for Pads 1-5A and Pad 6
Operate so as to avoid discharge from pond
spillway
Minimum standards for sampling of heaps
after rinsing during heap closure and
reclamation
Install groundwater monitoring wells
Place ore for leaching on Pad 6 no closer
than 20 feet from perimeter berms and/or
solution ditches
16,255
5/90
Hydrogen Peroxide Rinse System
(Modification of the chlorine rinsewater treatment
system consisting of an existing 20,000 gallon
carbon steel tank modified with internal baffles,
hydrogen peroxide storage and metering system
and "associated piping and appurtenances).
Submit sludge disposal plan within six
months of permit issuance
Maintain O&M manual for waste treatment
plant onsite
Update BMP plan
2-28
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Site Visit Report: Brewer Mine
Table 2-5. Construction Permits Issued to Brewer Gold Company (continued)
Permit
Number
Date
Nature of Permit
MaJor Itequlremente
16,727
Superseded
by 17,170
10/90
10/91
Pit Water Treatment System and Pond (permit
17,170)
(Existing 3,500,000 gallon pond with 60-mil
HOPE primary liner, 20-mil VLDPE secondary
liner on one-foot compacted clay base, and leak
detection system between liners; pit water
treatment system equipment and piping.
Maintain O&M Manual for treatment plant
on site
Submit updated BMP plan
Submit deactivation plan prior to temporary
cessation of mining activity
Maintain daily log on use of pit water for
dust control
Report any overflows from spillway
17,027
4/91
Pad 6 Overflow Pond Redesign
(Leak collection and recovery system including
construction of a concrete pipe encasement with
6" and 10" diameter HOPE pipe, two concrete
cutoff collars, portion of clay backfill which
supports encasement and portion of toe drain
which supports encasement).
N/A
17.052
5/91
Pad 6 Overflow Pond Reconstruction
(Rehabilitation and reconstruction of the Pad 6
Overflow Pond: 1) zoned earthfill structure with
seal zone on an upstream face, with chimney
drain connected to horizontal toe drain; (2)
impoundment with storage capacity of 18,900,000
gallons, emergency spillway, liner system [clay
seal zone beneath 60 mil HDPE primary liner and
40 mil VLDPE secondary liner, with geonet leak
collection and recovery system between secondary
and primary liners, extra layer of 60 mil HDPE
placed at the outflow of the overflow ditch, and
leak detection sump consisting of clean gravel
between 60 mil and 40 mil liners with volume of
approximately 5,400 gallons]; (3) network of
groundwater drains under liner system [clean
gravel surrounded by geotextile, with slotted
diameter pipe with minimum cross-section of 10
square feet, and removal and backfill with clay of
some of previous pond groundwater drains]; (4)
relining with 60 mil HDPE section of existing
overflow ditch from Pad 6 to Overflow pond; (5)
reinforced 10,000 gallon concrete outlet sump
outlet piping, pump with 2" diameter HDPE
piping encased in 4" diameter CPT pipe; (6) three
movement monuments, two toe monuments, two
standpipe piezometers, and three vibrating wire
piezometers; and (7) associated piping and
appurtenances).
Update BMP plan
Monitor leak detection sumps of Pad 6 and
overflow pond weekly for the life of the
project for liquid, pH, and total cyanide
Monitor groundwater underdrainage weekly
for pH, flow, and free cyanide
Maintain emergency generator onsite
Maintain O&M for waste treatment plant
onsite
These permits, as can be seen, have authorized construction and operation of all facility components.
They typically require submission of various engineering, operating, and maintenance reports and
studies. These construction permits also require monitoring of ground water near each major facility
component and closure plans for facility components. Altogether, there are 13 ground-water
monitoring wells: three for the Sediment Pond and waste rock piles, four for the solution ponds, four
2-29
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Site Visit Report: Brewer Mine
for Pad 6, one for the Pad 6 overflow pond (underdrainage from this pond is also monitored), and
one to the west of Pads 1-5. Locations of monitoring wells are shown in Figure 2-4. Background
water quality was established by sampling the original monitoring wells prior to the initiation of
leaching operations. Results of ground-water monitoring from 1988 to 1991 for five selected
parameters are presented in Tables 2-6 through 2-10. Background data were not available.
Should ground-water monitoring reveal a continuing violation of State drinking water standards (one-
time excursions would be verified before formal action was taken), DHEC could impose civil or
criminal penalties and/or require source control or remediation action. This has not been necessary to
date.
Sewage Treatment and Disposal System Permit. In addition to the permits discussed above, DHEC's
Bureau of Environmental Health, Division of On Site Waste Management also issued, in July, 1987,
Sewage Treatment and Disposal System Permit No. 13-62778 for a domestic sewage drain field. This
permit was not examined by the site visit team.
2.4.1.2 Bureau of Air Quality Control
DHEC's Bureau of Air Quality Control issues and enforces Air Emissions Permits under the South
Carolina Pollution Control Act and State Regulation 61-62.1. The Brewer Gold Company facility has
been issued a five-year operating permit (March 1989 - March 1994) and a construction permit.
Brewer's Permit No. 0660-0026, effective from March 20, 1989 through March 31, 1994, authorizes
operation of the following units (DHEC, 1989c):
ID No. 01: 400 ton/hour primary, secondary, and agglomerating plant. The permit
required Brewer to install water sprays for dust control in these areas.
ID No. 02: 40 ton capacity cement storage silo with fabric sock or bin vents.
ID No. 03: 1,000 gpm sodium cyanide leaching process for gold recovery with pH
controlled to greater than 10.S. Hydrogen cyanide concentrations may not exceed 250
micrograms per cubic meter at the plant boundary on a 24-hour basis.
ID No. 04: 15 pound/hour propane fired melting furnace for dore production.
Table 2-11 shows emission limitations established by the permit for these units. In addition to these
limits, the permit makes the facility subject to applicable New Source Performance Standards for
Metallic Mineral Processing (40 CFR Part 60, Subpart LL). The permit also requires that dust from
haul roads and turnaround areas be controlled by water sprays and water trucks and that stockpiles or
waste rock piles be sprayed with water when wind erosion creates excessive emissions (DHEC,
1989c).
2-30
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Site Visit Report: Brewer Mine
FaeWttot Layout
and Topography
Figure 2-4. Location of Monitoring Wells, Brewer Gold Mine
(Source: Brewer Gold Company, 1991g)
jytw-i
2-31
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Site Visit Report: Brewer Mine
Table 2-6. Monitoring Data From Wells Located Near Sediment Pond and
Waste Rock Disposal Area
Monitoring Weil/
Parameter
MW-1
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
MW-2
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
MW-2R
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
Minimum and Maximum Concentrations Detected (ppm, Except as Noted)
1988
n =* 4
4.7 - 5.9
<0.01 - <0.01
<0.01 - <0,01
<0.1 - <0.1
<2- <2
n 4
3.8 - 4.2
<0.01 - <0.01
<0.01 - <0.01
<0.1 - <0.1
<2-6.1
n =0
N/A
N/A
N/A
N/A
N/A
1989
n «4
4.48 - 4.9
<0.05 - <0.01
<0.01 - <0.01
<0.03-,<0.1
<0.2 - 4
n «4
4.06-4.14
<0.01 - <0.05
<0.01 - <0.01
<0.03 - <0.1
<0.2 - <2
n =0
. N/A
N/A
N/A
N/A
N/A
1990
n = 4
3.08 - 4.67
<0.01 - <0.01
0.0001 - <0.01
<0.03 - <0.05
<0.2 - 1.55
n = I
3.9
<0.01
<0.01
<0.03
<0.2
n.- 3
5.6 - 5.89
<0.01 - <0.01
0.0001 - <0.01
<0.03 - <0.05
0.16-0.18
1991
n = 2
3.99 - 4.26
<0.01 - <0.01
<0.001 - 0.002
0.1 -0.139
<0.2 - 0.6
n = 0
N/A
N/A
N/A
N/A
N/A
n -2
5.54 - 6.43
<0.01 - <0.01
<0.001 -
<0.001
0.003 - 0.013
0.21 - 0.36
SOURCE: Compiled from Brewer Gold Company, 199la.
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Site Visit Report: Brewer Mine
Table 2-7. Monitoring Data From Wells Located Near Solution Ponds
Monitoring Well/
Parameter
MW-3
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
MW^*
MW-7R
PH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
MW-12
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
Minimum and Maximum Concentrations Detected (ppm, Except as Noted)
1988
!n = 4
4.1-4.6
<0.01 - <0.01
<0.01 - <0.01
<0.1 - <0.1
<2-2
n=*Q
n = 0
N/A
N/A
N/A
, N/A
N/A
n *» 0
N/A
N/A
N/A
N/A
N/A
1989
a = 4
4.06 - 4.73
<0.05 - <0.01
<0.01 - <0.01
<0.03 - 0.04
0.2 - <2
n - 0
n = Q
N/A
N/A
N/A
N/A
N/A
n = 0
N/A
N/A
N/A
N/A
N/A
1990 ^
n «s 4
4.19-4.67
<0.01 - <0.01
<0.0001 - <0.01
<0.03 - <0.05
<0.2 - 1.43
n = 0
n = 4
3.89 - 4.88
<0.01 - <0.01
<0.010 - 0.0001
<0.03 - 0.04
3.5 - 7.7
(n-3)
n - 0
N/A
N/A
N/A
N/A
N/A
1991
n = 2.
4.33 - 4.57
<6.01 - <0.01
<0.001 - <0.001
0.023-0.155
0.5 - 0.6
n = 0
n = 2
5.54 - 6.43
<0.01 - <0.01
<0.001 - <0.001
0.004 - 0.009
1.2-5.2
n = 1
4.39
<0.01
<0.001
0.017
2.6
* Well has remained dry since construction.
SOURCE: Compiled from Brewer Gold Company, 1991a
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Site Visit Report: Brewer Mine
Table 2-8. Monitoring Data From Wells Located Near Leach Pad 6
"- "
Monitoring Well/
Parameter
MW-8
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
MW-9
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
MW-10
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
MW-H
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
Minbxnttn and Maximum Concentrations Detected (ppm, Except as Noted)
1988
n = 0
N/A
N/A
N/A
N/A
N/A
n * 0
N/A
N/A
N/A
N/A
N/A
n = 0
N/A
N/A
N/A
N/A
N/A
n « 0 .
N/A
N/A
N/A
N/A
N/A
1989
a = 0
N/A
N/A
N/A
N/A
N/A
n «0
N/A
N/A
N/A
N/A
N/A
n=0
N/A
N/A
N/A
N/A
N/A
n =0
N/A
N/A
N/A
N/A
N/A
1990
n=4
4.67 - 5.69
<0.01 - 0.04
(n = 5)
<0.010 - <0.0001
<0.03 - <0.05
<0.2 - 0.26
\
n « 4
4.7 - 4.9
<0.01 - <0.01
<0.010 - 0.0001
<0.03 - <0.05
<0.2 - 1
n »"4 ':
4.59 - 4.72
<0.01 - <0.01
<0.010 - 0.0001
<0.03 - <0.05
<0.2 - 0.4
n at 4
4.33 - 4.66
<0.01 - <0.01
<0.010 - 0.0001
<0.03 - <0.05
<0.2-0.5
1991
a*=2
4.53 - 4.67
<0.01 - <0.01
<0.001 - <0.001
0.005 - 0.01
<0.2 - 0.3
n = 2
4.61 - 4.68
<0.01 - <0.01
<0.001 - <0.001
0.005 - 0.015
<0.2 - <0.2
n»2
4.48 - 4.58
<0.01 - <0.01
<0.001 - 0.002
0.003 - 0.004
<0.2 - 0.7
a = 2
4.4 - 4.7
<0.01 - <0.01
< 0.001 - 0.001
0.004 - 0.072
<0.2 - <0.2
SOURCE: Compiled from Brewer Gold Company, 1991a
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Site Visit Report: Brewer Mine
Table 2-9. Monitoring Data From Well Located Near Pad 6 Overflow Pond and
From Pad 6 Overflow Pond Underdrain
Monitoring Weil/*
Parameter
MW-5
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
UD-1
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
Minimum and Maximum Concentrations Detected (ppm, Except as Noted)
1988
n = 4
4.0 - 4.7
<0.01 - <0.01
<0.01 - <0.01
<0.1 - <0.1
<2-<2
n = 6
N/A
N/A
N/A
N/A
N/A
1989
n = 4
4.65-6.18
<0.05 - <0.01
<0.01 - <0.01
< 0.03 -0.14
<0.2 - <2
a -Q
N/A
N/A
N/A
N/A
N/A
1990
0 = 4
3.89 - 4.25
<0.01 - <0.01
<0.01 - 0.01
0.09 - 0.84
0.38 - 5.45
a = 4
4.33 - 4.95
(n = 3)
<0.01 - 89.3
<0.01 - 0.0001
(n = 3)
0.96 - 1.59
(n = 3)
<0.2- 1.3
(n = 3)
1991
n = 2
4.29 - 3.98
<0.01 - 0.043
<0.001 - 0.004
0.13 - 1.51
0.5 - 0.8
n ~2
4.79 - 5.2
<0.01 - 0.094
<0.001 - <0.001
0.112-0.378
0.3 - 0.5
Source: Compiled from Brewer Gold Company, 1991a.
Table 2-10. Groundwater Monitoring Data From Well Located Near Topsoil Stockpiling Area
Monitoring Well/ \
Parameter :
MW-4 ;: : j
pH (s.u.)
Total Cyanide
Cadmium
Copper
Mercury (ppb)
Minimum and Maximum Concentrations Detected (ppm, Except as Noted)
1988
: n = 4
3.7-5.4
<0.01 - <0.01
<0.01 - <0.01
<0.1 - <0.1
<2- <2
1989
n = 4
4.63 - 4.9
<0.05 - <0.01
<0.01 - <0.01
<0.03 - <0.1
<0.2 - <2
1990
n = 4
3.61 - 6.94
<0.01 - <0.01
<0.01 -0.0001
<0.03 - <0.05
<0.2 - 1.58
1991
n = 2
4.59 - 5.03
<0.01 - <0.01
<0.001 - <0.001
0.002 - 0.049
2.5 - 3.7
Source: Compiled from Brewer Gold Company, 1991a.
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Site Visit Report: Brewer Mine
Table 2-11. Emission Limits Established by Permit 0660-0066
Unit ID
01
02
03
04
Pollutant
PM
Opacity
PM
Opacity
Opacity
Mercury
Arsenic
Opacity
Emission Limitation
22.4 pounds/hour or 98.11 tons/year
10 percent
10.125 pounds/day or 1.85 tons/year
20 percent
20 percent
0.0003 pound/hour or 0.0013 ton/year
0.01 pound/hour or 0.0044 ton/year
20 percent
Source: DHEC, 1989c.
Permit No. 0660-0026-CE, issued in July 1990 and expiring after one year, authorized the
construction of a 100-ton silo for storage of calcium cyanide to be pneumatically unloaded by trucks
and controlled by a bin vent fabric filter and an in-line disposal cartridge filter. Table 2-12 shows the
emission limitations for the storage silo (DHEC, 1990e). Operation of the silo requires an operating
permit, which may have been issued about the time of the site visit (the silo was operating at the time
of the visit).
Table 2-12. Emission Limits Established by Permit 0660-0026-CE
Pollutant
PM
Hydrogen cyanide (HCN)
Opacity
Emission Limitation
0.0009 pound/hour or 0.004 ton/year
2.10 pounds/hour or 9.2 tons/year
20 percent
Source: DHEC, 1990e.
The Bureau of Air Quality Control is authorized to seek civil and/or criminal penalties when permit
requirements are violated by a facility. Formal facility inspections are conducted by DHEC's
Florence District Office on an annual basis.
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Site Visit Report: Brewer Mine
2.4.2 Land Resources Commission
2.4.2.1 Division of Mining and Reclamation Mining Permit 671
Under the South Carolina Mining Act (Section 48-20 of the State Code), the Division of Mining and
Reclamation of the Land Resources Commission (LRC) is charged with ensuring that lands and waters
involved in mining are protected and restored to the "greatest practical degree." LRC's
responsibilities include issuing mining and reclamation permits, reviewing and approving reclamation
plans, collecting reclamation bonds, and inspecting facilities to ensure compliance. LRC coordinates
its activities with and supplements the regulatory activities of DHEC.
On July 16, 1986, LRC issued Mining Permit 671 for the Brewer facility (LRC, 1986); the permit
has been modified a number of times since to reflect changes in facility components and operations.
Table 2-13 summarizes the requirements of Mining Permit 671. To ensure compliance,
representatives of LRC make half-day inspections of the Brewer Gold Company facility on a monthly
basis and longer inspections periodically.
Mining Permit 671 authorizes operation of the Brewer mine from July 1987 through September 1996.
Initially, LRC required a reclamation bond of $170,000 (based on $1,000 per acre disturbed). This
was raised to $230,000 in November 1989 because of increased land disturbance associated with Pad
6. Based on a subsequent Brewer estimate of the cost of completing its reclamation/closure plan, the
bond was being raised to $500,000 (LRC, 1989a through d).
Brewer submitted a reclamation plan to LRC prior to operation. At the time, the S.C. Mining Act
did not specify reclamation as a part of closure. As amended in 1990, the Act now states clearly that
reclamation requirements for a mine facility are part of closure. Brewer's closure plans to date
(Brewer Gold Company, 1990b) are conceptual in nature; a final closure plan will be required prior
to actual closure.
Annual reclamation reports are required by LRC and are also required through construction permits
issued by DHEC. General reclamation/closure activities required of Brewer by LRC include the
following:
Waste Rock Dump: sloping (3:1), revegetation of sides and tops with grasses interspersed
with trees, and seepage/runoff pH testing
Leach Pads: sloping (3:1), removal of solution lines, revegetation with grasses (may also
require trees in the future)
Ponds: removal of liners and bulldozing
* Physical Plants and Building Structures: removal
Mine Pit: sloping of pit walls, revegetaiion. allowed to fill with water.
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Site Visit Report: Brewer Mine
Table 2-13. Major Requirements Established by Mine Permit 671
Facility /Operational Component
Major Requirements
Original Penmt 671; My 16, 1986
Ground water
Leach Pads and Ponds
Waste Rock
Cyanide Neutralization
Reclamation
Contingency Plans
Notification
May 13, 1988 Modification:
Pad 5
September 15, 1989 Modification:
Pads 5 and 5A
October 23, 1989 Modification:
Pads 5 and SA
November 7, 1989 Modification:
Pad*
December 8, 1989 Modification:
Pad6 T^X . ' :'
Characterize existing groundwater (depth, quality, etc.)
Establish background quality prior to leaching
Sample monthly and report to LRC
Install dual liners for pads: 40-mil primary, 18-inch
secondary with permeability < 1 x 10~7
Pregnant and barren ponds: HDPE primary liner, ditches,
etc.
Submit plan for acid-base testing
Establish alternative site for rock with acid generation
potential
Reduce free cyanide in heaps to 0.2 ppm
Outline study to project post-reclamation quality of pit water
Work with LRC on revegetation
Develop plan to verify/locate/correct leaks if cyanide detected
hi groundwater
Develop plan for mitigation of heavy rainfall and high winds
from hurricanes and storms
Notify LRC of pad leaks or cyanide detected in groundwater
Approval of asphalt pad for 10-cell on-off Pad 5
Monitor leak detection sumps for free cyanide, pH, gold
Change Pad 5 to dedicated Pad, construct Pad SA
Stack second lift (to 70 feet) on Pads 5 and 5A
Submit closure plan with six months
Begin rinsing Pads 1 through 5A by July 1, 1990, submit
status report by September 15, 1990
Clear Pad 6 area
Requirements to control runoff/sedimentation from
construction area
Construct Pad 6
Submit wildlife hazing plan, fence Pad 6 pond
Source: LRC 1986, 1988a, 1989a, 1989b, 1989c, 1989d.
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Site Visit Report: Brewer Mine
The S.C. Mining Act, as amended in 1990, gives the LRC authority to assess civil penalties for
noncompliance with the approved reclamation plan or schedule of reclamation. Penalties up to
$1,000 per day per violation are authorized. In addition, LRC works closely with DHEC, which has
additional authorities (as described above).
2.4.2.2 Engineering Division Dam Construction and Repair Permits
The LRC Engineering Division implements the Dam and Safety Reservoirs Act (section 49-11 of the
State Code). LRC has issued Brewer three dam construction permits and one dam repair permit.
These permits and the activity or facility component/operations covered are listed hi Table 2-14.
These permits were not examined by the site visit team.
Table 2-14. Dam Construction and Repair Permits Issued to Brewer Gold Company
Permit Number
13-447-P394
13-537-P475
13-527-P522
13-602-P522
Date Issued
7/87
3/90
5/91
6/91
Nature of Permit
Sediment Pond Construction
Overflow Pond Construction
Pit Water Treatment Pond Construction
Overflow Pond Dam Repair
2.4.3 Other Regulatory Agencies and Permits
The following permits have also been issued to the Brewer Gold Company:
South Carolina Fire Marshal Blasting Permit No. 91-177
U.S. Department of the Treasury - Bureau of Alcohol, Tobacco, and Firearms High
Explosives License No. 1-SC-013-33-1L-92336
These permits were not examined by the site visit team.
2-39
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Site Visit Report: Brewer Mine
2.5 REFERENCES
A.S.C.I. 1989 (September 13). Review of Cyanide Rinse and Neutralization Data: Brewer Gold
Mine Heap Leach, S.C. Letter from A.S.C.I. to W. Rose, Brewer Gold Company. Appendix
B of Mine Closure Plan (Brewer Gold Company, April 1990a).
A.S.C.I. 1990 (April). Abatement Plan for Potential Acid Mine Drainage Associated with Closure
of the Brewer Mine. Prepared for Brewer Gold Company. Appendix A of Mine Closure Plan
(Brewer Gold Company, April 1990a).
Brewer Gold Company. Undated. "Brewer Gold Mine." Unpublished brochure providing history
and description of Brewer Gold Mine.
Brewer Gold Company (Westmont Mining Inc.). 1987a (March 27). Letter from RJ. McGregor,
Brewer Gold Company to N. Weatherup, S.C. DHEC, RE: Response to March 24, 1987 letter
from N. Weatherup, DHEC.
Brewer Gold Company, 1987b (December 23). Letter from W.T. Lyman, Brewer Gold Company to
G. Stowe, S.C. DHEC, RE: Heap Pile Mud Flow, December 16, 1987.
Brewer Gold Company. 1988 (February 10). Letter from R.J. McGregor, Brewer Gold Company to
J.W. Wilkinson, S.C. DHEC, RE: Request for extension of Consent Order 87-113-W, section
5 deadline.
Brewer Gold Company. 1988a (February 15). Letter from R.J. McGregor, Brewer Gold Company
to N. Weatherup, S.C. DHEC, RE: leak detection system report.
Brewer Gold Company, 1988b (April 7). Letter from R.J. McGregor, Brewer Gold Company, to C.
Kennedy, S.C. LRC, RE: Heap leach pad rinsing (remove Pad 1 from recirculation to begin
rinsing).
Brewer Gold Company. 1988d (April 4 and 5). Letters from L. Harnage, Brewer Gold Company to
R. Kinney, S.C. DHEC, RE: cyanide spill on March 31, 1988.
Brewer Gold Company. 1988e (April 22). Letter from R.J. McGregor, Brewer Gold Company, to
E. Hart, S.C. DHEC, RE: Calculations on March 31 and April 5, 1988 spills of 600 ppm
cyanide solution.
Brewer Gold Company. 1988f (June 24). Letter from J.J. Harrington, Brewer Gold Company to E.
Hart, S.C. DHEC, RE: June 24, 1988 incident report.
Brewer Gold Company. 1989 (February 17). Letter from D. Williams, Brewer Gold Company, to
E. Hart, S.C. DHEC, RE: Emergency Pond leak.
Brewer Gold Company. 1989a (February 27). Letter from J.B. Pautler, Brewer Gold Company to
E. Hart, S.C. DHEC, RE: February 26, 1989 incident report.
Brewer Gold Company. 1989b (April 26). Memorandum to file from W.L. Rose, Brewer Gold
Company; submitted to S*.C. DHEC. Subject: Sediment pond discharge (and events
surrounding).
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Site Visit Report: Brewer Mine
Brewer Gold Company. 1989c (April 26). Letter from W.L. Rose, Brewer Gold Company, to N.
Weathemp, S.C. DHEC, RE: response to DHEC letter dated 4/7/89 that requested information
on rinsewater pond overflow, cyanide destruction system).
Brewer Gold Company. 1989d (July 20). Letter from J.B. Pautler, Brewer Gold Company to J.
Wilkinson, S.C. DHEC, RE: report of spent ore slide and cyanide spill en July 16, 1989.
Brewer Gold Company. 1989e (July 28). Memorandum to file from W.L. Rose, Brewer Gold
Company; submitted to S.C. DHEC. Subject: Sediment pond water treatment (including plant
history), request for treatment and discharge.
Brewer Gold Company. 1990 (March 12). Letter from S. Wanstedt, Brewer Gold Company, to E.
Hart, S.C. DHEC, RE: "Barren Pond Leakage" into leak detection sump.
Brewer Gold Company. 1990a (March 22 and April 3). Letters from S. Wanstedt, Brewer Gold
Company, to K. Terry and E. Hart, S.C. DHEC, respectively, RE: Update on Pad 5 leakage.
Includes memorandum to files from S. Wanstedt submitted to S.C. DHEC.
Brewer Gold Company. 1990b (April). Mine Closure Plan, Brewer Gold Mine, Chesterfield
County, South Carolina. Submitted to S.C. DHEC.
Brewer Gold Company. 1990c (April 27). Letter from S. Wanstedt, Brewer Gold Company, to C.
Kennedy, S.C. LRC, RE: Pad 6 slope failure preliminary report.
Brewer Gold Company. 1990d (April 27). Letter from S. Wanstedt, Brewer Gold Company, to B.
Ruiter, S.C. DHEC, RE: "Use of hypochlorite...in the control of ... cyanide present in the clay
liner due to the Pad 6 slope failure."
Brewer Gold Company. 1990e (August 22). Letter from S. Wanstedt, Brewer Gold Company, to J.
Wilkinson, S.C. DHEC, RE: Incident report for August 20, 1990, cyanide spill.
Brewer Gold Company. 1990f (May 24). Letter from S. Wanstedt, Brewer Gold Company, to E.
Hart, S.C. DHEC, RE: Notification of end of incident involving leakage from Pad 5 sumps.
Brewer Gold Company. 1990g (October 19). Letter from S. Wanstedt, Brewer Gold Company, to
E. Hart, S.C. DHEC, RE: "Discharges from the Rinse and Sediment Pond emergency
spillways" on October 10, 1990, and Summary of Events leading to discharges.
Brewer Gold Company. 1990h (October 26). Letter from S. Wanstedt, Brewer Gold Company, to
G. Stowe, S.C. DHEC, RE: Description of leakage in leak detection system since October 10-
11 storm.
Brewer Gold Company. 1990i (November 14). Letter from R.S. Mattson, Brewer Gold Company,
to M.D. Jarrett, S.C. DHEC, RE: Request for administrative adjudicatory hearing raised by
NPDES Permit No. SC0040657.
Brewer Gold Company. 1990J (November 27). Letter from S. Wanstedt, Brewer Gold Company, to
J. Wilkinson, S.C. DHEC, RE: Discharges during October 1990 under NPDES Permit
SC0040657 (letter accompanying October 1990 Discharge Monitoring Report).
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Site Visit Report: Brewer Mine
Brewer Gold Company. 1991a. Compilation of ground-water monitoring data, 1988-1991. Provided
as attachment of letter from S. Wanstedt, Brewer Gold Company, to J. Mozingo, SAIC,
September 28, 1991 (Brewer Gold Company, 1991g).
Brewer Gold Company. 1991b (April 22). Brewer Project Site Hydrological Assessments.
Submitted to S.C. Department of Health and Environmental Control.
Brewer Gold Company. 1991c. NPDES Permit SC0040657, Discharge Monitoring Reports for
March, April, May, June, July, and August 1991. Submitted to S.C. Department of Health and
Environmental Control, Water Quality Assessment and Enforcement Division.
Brewer Gold Company. 1991d (May 14). Letter from R.C. Walish, Brewer Gold Company to B.
McDade, S.C. DHEC, RE: response to April 26, 1991, letter requesting details of Brewer Gold
Company's appeal to draft NPDES permit.
Brewer Gold Company. 1991e (June 17). "Brewer Rinsing Status Report and Schedule." Submitted
by R. Walish, Brewer Gold Company, to J. Wilkinson, S.C. Department of Health and
Environmental Control.
Brewer Gold Company. 1991f (July 12). "Treatment Pond Sludge Status Report and Sludge
Disposal Schedule." Submitted by S. Wanstedt, Brewer Gold Company, to J. Wilkinson, S.C.
Department of Health and Environmental Control.
Brewer Gold Company. 1991g (September 28). Letter from S. Wanstedt, Brewer, to J. Mozingo,
SAIC, on chemical purchases by Brewer Gold Mine.
Cargo, D.N. and B.F. Mallory. 1977. Man and His Geologic Environment. Second Ed. Addison-
Wesley Publishing Company. Reading, Mass. 581 pp.
Environmental and Chemical Services, Inc. 1987. "An Ecological Assessment of the Brewer Mine
Site, Chesterfield County, S.C." Prepared for Nicor Mineral Ventures. Submitted to S.C. Land
Resources Commission as Appendix B of Application for Permit to Mine.
Haynsworth, Baldwin, Johnson and Greaves, P.A. 1990 (December 18). Petition for Revision of
NPDES Permit (No. SC0040657], submitted to S.C. DHEC on behalf of Brewer Gold
Company.
Scheetz, J.W., J.M. Stonehouse, and M.R. Zwaschka. 1991 (January). "Geology of the Brewer
Gold Mine in South Carolina." Mining Engineering, pp. 38-42.
Shealy Environmental Services, Inc. 1991 (May). "A Macroinvertebrate and Fish Assessment
Conducted for Brewer Gold Mining Company, Chesterfield County, Jefferson, South Carolina."
Prepared for Brewer Gold Mining Company. Revision of March 1991 Report.
Sirrine Environmental Consultants. 1990 (November 29). Removal Action Plan, Brewer Gold
Company, Jefferson, South Carolina. Submitted to U.S. Environmental Protection Agency
Region IV on behalf of Brewer Gold Company.
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Site Visit Report: Brewer Mine
Sirrine Environmental Consultants. 1991 (April 8). Removal Action Assessment, Brewer Gold
Company, Jefferson, South Carolina. Submitted .to U.S. Environmental Protection Agency
Region IV on behalf of Brewer Gold Company.
State of South Carolina, Department of Health and Environmental Control. Undated. General Mine
Information (fact sheet on Brewer Gold Mine).
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1986. Water Pollution Control Permit issued to Westmont Mining, Inc. (NPDES
Permit SC0040657, effective December 1, 1986).
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1987a (April 14). Construction Permit 13,135 issued to Westmont Mining, Inc.,
Brewer Project (for construction of 846,000 gallon sedimentation pond).
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1987b (May 4). Construction Permit 13,172, with special conditions, issued to
Brewer Mine (for construction of treatment tanks, 54,000 gallon holding pond, and recirculation
process system [1,999,000 pregnant pond, 901,000 barren pond, 8,900 gallon rinse pond, four
180,000 square foot leach pads and associated piping]). Modified by permit special conditions
in DHEC letter dated August 12, 1988 and in Construction Permit 16,255, issued May 24,
1991.
State of South Carolina, Department of Health and Environmental Control. 1987c (November 25).
Consent Order 87-113-W; IN RE: Westmont Mining Inc./Brewer Gold Mine, NPDES No.
SC0040657, Chesterfield County.
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1988b (May 16). Construction Permit 14,217, with special conditions, issued to
Brewer Gold Company (for construction of asphalt leach pad [425,100 square feet] with french
drain leak detection system, two 1,100 gallon two-stage solution pumps, leak detection sump,
and 3,600,000 gallon pregnant pond with piping/appurtenances). Includes modifications to
permit special conditions issued August 12, November 4, and December 14, 1988.
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1989a (September 26). Construction Permit 15,699, with special conditions, issued to
Brewer Gold Company (for construction of flocculation system for sediment pond [and
associated pumps, tanks, etc.]).
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1989b (December 8). Construction Permit 15,869, with special conditions, issued to
Brewer Gold Company (for construction of Pad no. 6 [1,100,000 square feet, with leak
detection sump, 10,000 gallon sump, associated pumps/piping]; and 17,500,000 gallon overflow
pond and leak detection sump with associated pumps/piping.)
State of South Carolina, Department of Health and Environmental Control, Bureau of Air Pollution
Control. 1989c (March 20). Operating Permit 0660-0026 issued to Brewer Gold Company
State of South Carolina, Department of Health and Environmental Control. 1990a. Spill Report and
Emergency Response Investigation (on spill of October 28, 1990).
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Site Visit Report: Brewer Mine
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1990c. Water Pollution Control Permit issued to Brewer Gold Company (NPDES
Permit SC0040657, effective December 1, 1990). Modifications to 12/1/86 NPDES Permit
(DHEC, 1986).
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1990d (May 24). Construction Permit 16,255, with special conditions, issued to
Brewer Gold Company (for modification to chlorine rinsewater treatment system [modification
to permit 13,172]).
State of South Carolina, Department of Health and Environmental Control, Bureau of Air Pollution
Control. 1990e (July 18). Construction Permit 0660-0026-CE issued to Brewer Gold
Company.
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1990f (September 22). Construction Permit 15,697, with special conditions, issued to
Brewer Gold Company (for construction of Pad 5A [60,000 square feet] and modification of Pad
5 from reusable to dedicated leach pad.]
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1990g (October 29). Construction Permit 16,727, with special conditions, issued to
Brewer Gold Company (for construction of pit water treatment system [as described]).
State of South Carolina, Department of Health and Environmental Control, Water Pollution
Assessment and Enforcement Division. 1991a (April 9). Notice of Enforcement Conference,
NPDES Permit SC0040657, and Findings of Fact.
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1991b (April 12). Construction Permit 17,027, with special conditions, issued to
Brewer Gold Company (for construction of leak detection and recovery system associated with
redesigned Pad 6 overflow pond.)
State of South Carolina, Department of Health and Environmental Control, Bureau of Water Pollution
Control. 1991c (May 13). Construction Permit 17,052, with special conditions, issued to
Brewer Gold Company (for redesigned Pad 6 overflow pond and dam).
State of South Carolina, Department of Health and Environmental Control. 1991d (June 6). Consent
Order 91-30-W; IN RE: Brewer Gold Company, NPDES SC0040657, Chesterfield County.
State of South Carolina, Land Resources Commission, Division of Mining and Reclamation. 1986
(July 16). Brewer Mine, Permit No. 671, Additional Terms and Conditions.
State of South Carolina, Land Resources Commission, Division of Mining and Reclamation. 1988a
(May 13). Approval and conditions for Brewer Gold Company application to modify permit 671
(modify leach pad liner from clay and synthetic liner and to deposit leached, rinsed ore on
existing pads).
State of South Carolina, Land Resources Commission, Division of Mining and Reclamation. 1988b
(July 28). Letter from C. Kennedy, S.C. LRC to J. Harrington, Brewer Gold Company, RE:
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Site Visit Report: Brewer Mine
Mining permit 671, Release of process solution from Pad no. 3 (500-600 gallons of 600r700
ppm pregnant solution). .
State of South Carolina, Land Resources Commission, Division of Mining and Reclamation. 1989a
(September 15). Approval and conditions for Brewer Gold Company application to modify
permit 671 (construct new pad 5A).
State of South Carolina, Land Resources Commission, Division of Mining and Reclamation. 1989b
(October 23). Approval and conditions for Brewer Gold Company application to modify permit
671 (second lift on pads 5 and 5A).
State of South Carolina, Land Resources Commission, Division of Mining and Reclamation. 1989c
(November 7). Approval and conditions for Brewer Gold Company application to modify
permit 671 (Prepare for construction of pad 6: clearing, grubbing, sediment control, clay
removal).
State of South Carolina, Land Resources Commission, Division of Mining and Reclamation. 1989d
(December 8). Approval and conditions for Brewer Gold Company application to modify permit
no. 671 (construct pad 6).
Steffen Robertson & Kirsten (Colorado) Inc. Undated (1987). "As-Built Report and Plans for the
Brewer Gold Project, Chesterfield County, South Carolina.11 Prepared for Westmont Mining,
Inc., and Brewer Gold Company.
Steffen Robertson and Kirsten (U.S.) Inc. 1990 (April). "Interim Rinse and Treatment System
Application for Permit to Construct Sewage and Industrial Waste Treatment System, Brewer
Project, Chesterfield County, South Carolina." Prepared for Brewer Gold Company.
U.S. Environmental Protection Agency, Region IV. 1990. Administrative Order (EPA Docket 91-
06-C). Issued to Brewer Gold Mine (following October 1990 dam failure)
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Site Visit Report: Brewer Mine
APPENDIX 2-A
COMMENTS SUBMITTED BY BREWER GOLD COMPANY
ON DRAFT SITE VISIT REPORT
2-46
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Site Visit Report: Brewer Mine
[Comments not reproduced for this electronic draft.
Copies may be obtained from U.S. EPA, Office of
Solid Wastes, Special Waste Branch.]
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Site Visit Report: Brewer Mine
APPENDIX 2-B
COMMENTS SUBMITTED BY SOUTH CAROLINA
DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL
ON DRAFT SITE VISIT REPORT
2-48
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Site Visit Report: Brewer Mine
[Comments not reproduced for this electronic draft.
Copies may be obtained from U.S. EPA, Office of
Solid Wastes, Special Waste Branch.]
2-49
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Site Visit Report: Brewer Mine
APPENDIX 2-C
COMMENTS SUBMITTED BY
SOUTH CAROLINA LAND RESOURCES COMMISSION
ON DRAFT SITE VISIT REPORT
2-50
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Site Visit Report: Brewer Mine
[Comments not reproduced for this electronic draft.
Copies may be obtained from U.S. EPA, Office of
Solid Wastes, Special Waste Branch.]
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Site Visit Report: Brewer Mine
APPENDIX 2-D
EPA RESPONSES TO BREWER GOLD COMPANY COMMENTS
ON DRAFT SITE VISIT REPORT
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Site Visit Report: Brewer Mine
EPA Response to Brewer Gold Company's
Comments on Draft Site Visit Report
Comment: Brewer, in its February 11, 1992, comments (see Appendix 2-A), stated that the
report's inclusion (on pages 49 and 50 of the draft report, pages 52 and 53 of the
present report) of violations listed in the April 9, 1991, Notice of Enforcement
Conference gave a misleading impression of the company's operations and compliance
record. Brewer indicated that the resolution of the issues on June 6, 1991 [hi Consent
Order 91-30-W] was not mentioned in the draft report and that some of the listed
violations were without basis, were cleared up once miscommunications were
discovered, or the intent on Brewer's part to protect the "environment were made
clear. Brewer requested that the list of violations be deleted.
Response: EPA believes the list of violations alleged hi the Notice is relevant, since a finding of
the Consent Order was that violations had occurred "on several occasions." However,
EPA notes that the Consent Order did not cite any specific violations. As a result,
EPA has deleted the discussion of the Notice and the Order from the report.
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Site Visit Report: Brewer Mine
APPENDIX 2-E
<
EPA RESPONSE TO COMMENTS SUBMITTED BY
SOUTH CAROLINA DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL
AND SOUTH CAROLINA LAND RESOURCES COMMISSION
ON DRAFT SITE VISIT REPORT
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Site Visit Report: Brewer Mine
EPA Response to Comments, Submitted by
South Carolina Department of Health and Environmental Control
and South Carolina Land Resources Commission
on Draft Site Visit Report
EPA has revised the report to incorporate all of the comments submitted by DHEC (see Appendix 2-
B) and LRC (see Appendix 2-C). In some cases, EPA made minor changes to wording suggested by
DHEC and/or LRC in order to attribute the changes to the State or to enhance clarity.
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Site Visit Report: Colosseum.Mine
MINE SITE VISIT:
COLOSSEUM MINE
U.S. Environmental Protection Agency
Office of Solid Waste
401 M Street SW
Washington, DC 20460
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Site Visit Report: Colosseum Mine
3.0 SUE VISIT REPORT: COLOSSEUM MINE
3.1 INTRODUCTION
3.1.1 Background
i
The Environmental Protection Agency (EPA) is assisting states to improve their mining programs.
As part of this ongoing effort, EPA is gathering data related to waste generation and management
practices by conducting site visits to mine sites. As one of several site visits, EPA visited Colosseum
Mine near Las Vegas, Nevada, May 7, 1992.
Sites to be visited were selected to represent both an array of mining industry ..sectors and different
regional geographies. All site visits have been conducted pursuant to RCRA Sections 3001 and 3007
information collection authorities (see Appendix 3-A). When sites have been on Federal land, EPA
has invited representatives of the land management agencies (Forest Service and/or Bureau of Land
Management). State agency representatives and EPA regional personnel have also been invited to
participate hi 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 get initial information, (2) contacting State
regulatory agencies by telephone to get further information, and (3) conducting the actual site visit.
Information collected prior to the site visit is then reviewed and confirmed during the site visit.
In preparing this report, EPA collected information from a variety of sources, including, Colosseum,
Inc. and the Bureau of Land Management (BLM). The following individuals participated in the
Colosseum Mine site visit on May 7, 1992:
Colosseum Mine
John Trimble, General Manager (702) 367-3883
Paul Nordstrom, Technical Services Coordinator (702) 367-3883
Lynn Holden, Chief Metallurgist . (702)367-3883
Larry Pawlosky, Mine Superintendent (702) 367-3883
U.S. EPA
Van Housman, Chemical Engineer (703) 308-8419
Patti Whiting, Environmental Protection Specialist (703) 388-8421
Haile Mariam, Chemical Engineer (703) 308-8439
Lisa Jones, Chemical Engineer (703)308-8451
Anita Cummings, Environmental Protection Specialist (703) 308-8303
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Site Visit Report: Colosseum Mine
Science Applications International Corporation
Ingrid Rosencrantz, Environmental Scientist
Laurie Lamb, Geologist
Bureau of Land Management
Bill Wiley, Environmental Protection Specialist
Robert Waiwook, Mineral Examiner
California State Water Resources Control Board
Rick Humphreys, Geologist
Bud Eagle, Geologist
(703) 734-2508
(303) 292-2074
(619) 326-3896
(7l4) 697-5300
(916) 739-4254
(916) 739-4194
Participants in the site visit were provided an opportunity to comment on a draft of this report.
Colosseum Inc. submitted comments, which are presented in Appendix 3-A. EPA responses to
comments by Colosseum are presented in Appendix 3-B.
3.1.2 General Facility Description
Colosseum Inc., a subsidiary of Lac Minerals Ltd., conducted mining and cyanide (carbon-in-pulp)
leaching of gold/silver ore in the Clark Mountain Range of southeastern California from 1988 to 1993
(see Figure 3-1). Mining operations ceased on July 10, 1992. Milling operations continued until
May 1993. The mine and mill are located in San Bernardino County, California, approximately 50
miles southwest of Las Vegas, Nevada. The closest developed area to the mine (12 miles) is Whiskey
Pete's, Nevada, a roadside development of casinos, gas stations and fast food restaurants on Interstate
15 at the Nevada/California state line.
The mining facilities occupy 284 acres with another 3,316 acres held as private land and unpatented
mining claims. Mining was conducted in two open pits, the South Pit and the North Pit. Most of the
mining facility lies on unpatented Federal land under the jurisdiction of the Bureau of Land
Management (BLM); but two patented claims are located in the South Pit. Land use in the vicinity of
the mine includes grazing and recreation. A large BLM grazing lease overlaps the mine/mill/tailings
complex. The mine is located within the boundaries of the East Mojave National JScenic Area and the
Clark Mountain Area of Critical Environmental Concern. These areas provide for limited multiple
use of public lands within their boundaries. In addition, one Wilderness Study Area borders the
property held by Colosseum Inc. (Bureau of Land Management, et al., 1985a)
The mine is within the old Clark Mountain Mining District, which produced silver, gold, copper,
lead, tungsten and fluorite at various times over the last 120 years. Gold was first produced m the
district in the 1930s. In the 1970s, Draco Mines and their partners performed intermittent exploration
drilling on the Colosseum property. Amselco leased the property from Draco Mines hi 1982 and
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Site Visit Report: Colosseum Mine
COLOSSEUM
PROJECT
SITE
...SAN BERNARDINO COUNTY LINE
Figure 3-1. Location of Colosseum Mine
(Source: Bureau of Land Management, et al., 1985a)
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Site Visit Report: Colosseum Mine
conducted extensive drilling and feasibility studies between 1982 and 1984. Amselco began the
required permit applications in 1983 and a Final Environmental Impact Report and Environmental "
Impact Statement was approved in July 1985 (see section 3.4.1).
Dallhold Resources, Inc., purchased the Colosseum property in September 1986. Sometime after this
purchase, Dallhold Resources, Inc., became part of Bond International Gold, Inc. Mine and mill
construction began hi 1987 and the mill began operation hi January 1988. In November 1989, the
Colosseum Mine changed ownership once more when Lac Minerals, Ltd., acquired the mine through
their purchase of Bond International Gold, Inc.'s properties. Colosseum, Inc., a subsidiary of Lac
Minerals Ltd., operated the Colosseum mine until July 10, 1993. (Attaway, Undated; Bond Gold
Colosseum, Inc., 1990; Holden, H.L. 1991)
The mill was active seven days a week, twenty-four hours a day and the open-pits were mined
Monday through Friday, rune hours a day. On average, the mine employed 110 people, with peak
employment of 300 during the construction of the facilities in 1987. The mine employed 94 people hi
May 1992: 55 employees of Colosseum Inc. and 39 employees of the contract mining company,
Industrial Contractors Corporation.
In 1990, total reserves were estimated at 3.9 million tons of ore with an average grade of 0.040 troy
ounces of gold per ton. As of July 12, 1990, Colosseum had produced over 170,000 troy ounces of
gold. (Bond Gold Colosseum, 1990b).
On July 10, 1992, Colosseum ceased mining after four and one-half years of operation. Milling of
stockpiled ore continued until May of 1993. According to Colosseum personnel, there are no plans to
continue mining due to a variety of economic reasons. Reclamation has been ongoing. (Colosseum
Inc., 1992e)
3.1.3 Environmental Setting
The Colosseum Mine lies hi the southern end of the Great Basin Physiographic Province hi the Clark
Mountain Range (see Figure 3-2). The Great Basin Province is characterized by valley and range
topography that resulted from block faulting during Tertiary tune. The Clark Mountains reflect this
topographic expression, being bounded by Ivanpah Valley on the east, Shadow Valley on the west and
Mesquite Valley to the north.
The minels located between 5,000 and 6,000 feet above sea level on the northeast side of Clark
Mountain, the highest peak hi the range at 7,929 feet above sea level. The mine and mill buildings
occupy the northern end of a gently sloping plateau-like area, which extends from the north flank of
Clark Mountain to the two open pits. Colosseum Gorge dissects the northern end of this plateau-like
area to the east and an unnamed dry wash dissects the area on the west.
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Site Visit Report: Colosseum Mine
Figure 3-2. Topographic Setting of the Colosseum Mine
(Source: Bureau of Land Management, et al., 1985a)
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Site Visit Report: Colosseum Mine
The climate is that of a high, mid-latitude desert, characterized by very low precipitation and large
diurnal temperature fluctuations. Annual precipitation (virtually all in the form of rain) at Mountain
Pass, approximately six miles south-southeast of the mine site and at a higher elevation, averages
between 10 and 12 inches. Most of the precipitation falls during November and December as frontal
winter storms pass over the mountains and in the spring and summer from convectional
thunderstorms. According to Colosseum personnel, since the start of mining, precipitation has
averaged less than seven inches per year (as measured by a rain gauge at the mine). As of May
1992, the mine had received slightly less than six inches of precipitation for the year.
Temperatures in the region experience large ranges due to the efficient heating and cooling of the
earth under the generally clear skies. As of 1,980, the mean maximum temperature at Mountain Pass
was 85.8 degrees Fahrenheit (°F) and the mean daily minimum temperature was 46.1°F. Prevailing
winds at the mine are from the northwest, with significant southerly flows. Diurnal wind data
indicates a typical up- valley/down-valley pattern of air movement. During the day, warming air in
the valleys rises up the drainages, and through the late night and early morning, cooled air travels
back down the drainages.
Habitat for the Desert Tortoise (a Federal endangered species) exists in Ivanpah Valley, along the
main access road to the mine. In addition to the road, the other main disturbance to the Desert
Tortoise habitat is a fresh water pipeline that carries water from supply wells in the valley to the
mine. Speed controls, elevated pipelines and regular sweeps of the road have been implemented by
Colosseum through their operating permit to protect the Desert Tortoises living in Ivanpah Valley (see
section 3.4). '
3.1.4 Geology
-,
Igneous and sedimentary rocks of Precambrian and Paleozoic age form the structurally complex Clark
Mountain Range. The mine lies in the Clark Mountains between two major faults: to the west of the
mine is the north-northwest trending Clark Mountain thrust fault and to the east is the high-angle
Ivanpah normal fault, which extends northwest-southeast through Ivanpah Valley (see Figure 3-3).
The Clark Mountain thrust fault creates an unconformity between Precambrian granitic gneiss to the
east of the fault and Cambrian sedimentary rocks to the west of the fault. (Bureau of Land
Management, et al., 1985a)
The ore body mined by Colosseum consists of two small mineralized felsite breccia pipes (north and
south) intruded into the Precambrian granite gneisses. The breccia pipes are estimated to be 100
million years old (mid to late Cretaceous). Each breccia pipe is approximately 500 feet x 300 feet
wide and extends to over 1500 feet deep.
A felsite breccia dike connects the two pipes. The emplacement and mineralization of the pipes is
thought to have occurred through the intrusion of rhyolite bodies followed by multiple explosive
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Sire Visit Report: Colosseum Mine
tSMCOUS HOCKS
r I ouATCmuflY ALLUVIUM
MCSOZOK
MLtOZOK CANtONATt MOCKS
MLCOZOIC CLASTIC HOCKS
NOCKS
MCSOZOK ONANITC NOCKS
JUNASSK-TNIASSK HCTMOLCtHK NOCKS
TMNUST FAULT - TtCTH w
FAULT DOTTED *« mrtMto
Figure 3-3. Colosseum Site Geology
(Source: Bureau of Land Management, et al., 198Sa)
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Site Visit Report: Colosseum Mine
hydrothermal fluid movements. (Bond Gold Colosseum, Inc, 1990; McClure, 1988)
Most of the mine facilities are located on soils weathered from Precambrian crystalline rocks. The
contact between the Precambrian crystalline rocks and the Cambrian sedimentary rocks is just west of
the mine buildings, near the tailings impoundment. Thin and discontinuous alluvial deposits are
found hi drainages around the facility area.
Two wells (MW1 and MW3, see section 3.3.2) drilled downgradient of the tailings impoundment
intersect Cambrian sedimentary rocks after drilling through alluvial materials (Sergent, et al.,
Undated). One well intersects the Cambrian rocks at three feet below the ground surface and the other
at 90 feet below ground surface. This 87 foot offset may suggest that a high angle fault extends
between the two closely spaced wells. According to Colosseum, the difference in Cambrian contact
elevation may simply be the result of stream erosion.
%
The gold mineralization hi the breccia pipes is submicroscopic and occurs with silver in close
association with pyrite (the ratio of gold to silver is 1:1). Gold occurs hi contact with pyrite, in .
pyrite fractures, along pyrite grain edges, and encased hi pyrite crystals. A low percentage (around
IS percent) of silver is found with the gold as electrum, a natural alloy; the rest is believed to be
present hi silver minerals (McClure, 1988). Other metals found hi the ore include lead, zinc, copper,
arsenic, and mercury. According to Colosseum personnel, very little mercury is found hi the ore.
The two pipes have been mined hi two separate open pits: the North Pit with an average grade of
0.04 troy ounce of gold per ton and the South Pit with an average grade of .067 troy ounce of gold
per ton.
Recent history indicates that the .Colosseum Mine is located hi an area of relatively minor seismic
activity. From 1932 through 1977, no earthquakes of Richter Magnitude 4 or greater were recorded
within a 50 mile radius of the mine. However, for the design of the tailings impoundment, seismic
studies were conducted to determine the Maximum Credible Earthquake (MCE). The MCE was
determined to occur along the Ivanpah Fault (see Figure 3-3) at Richter Magnitude 6.0. (Bureau of
Land Management, et al., 1985a)
3.1.5 Surface Water
No perennial streams exist hi the vicinity of the Clark Mountains. During the site visit, the EPA
team observed no water hi the ephemeral channels at the site. Information on when and how much
water is conveyed in these drainages was not obtained. Springs hi the Colosseum Gorge support
intermittent streams and watering holes southeast of the mine along the Old Gorge road. According
to Colosseum, all of the haul roads, pits, and mill area drain to the tailings impoundment. Other
mine areas, including the waste rock piles drain directly to Shadow Valley.
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Site Visit Report: Colosseum Mine
3.1.6 Ground Water
According to the EIS, hydrogeologic studies (author unknown) at the mine site suggest that ground
water resources are limited, existing primarily in fractured bedrock (Precambrian gneiss). However,
regional ground-water systems exist in the valleys surrounding the Clark Mountain Range: Ivanpah,
Shadow and Mesquite Valleys. These ground-water systems are at least ten miles from the mine and
are at elevations approximately 2,000 to 3,000 feet below the mine. Recharge to these systems
occurs through direct precipitation and runoff from the surrounding mountains (including the Clark
Mountains). (Bureau of Land Management, 1985a)
Ground water exists in fractured Precambrian gneiss at the mine site. According to Colosseum, five
(of nine) site monitoring wells contain water. Green's well, an old livestock watering well now
beneath the tailings impoundment, also contained water. All of these wells were completed in
bedrock. Depth to water in these wells (total depth of wells was not available) ranges between 14 and
67 feet below ground surface. Green's well and mine shafts (see Section 3.3.2 for further
discussions), located in the middle of the tailings impoundment, were estimated as over 350 feet deep
and as containing ground water at a depth of 55 feet below ground surface (Bureau of Land
Management, 1985a).
The gneisses are of low permeability: field tests indicate hydraulic conductivity ranges from 3 x 10~7
to 9 x 10"* centimeters per second. Transmissivity calculated from results of aquifer tests ranged
from 24 to 52 gallons per day per foot. According to the EIS, these very low values indicate
groundwater exists hi the fractured bedrock, but that existing water flows at very low velocity and is
subject to very little recharge from surface runoff (exact data on recharge were not provided in the
EIS). Baseline geologic and hydrogeologic studies completed prior to the approval of the mine state
that these aquifer properties limit the vertical or lateral hydraulic connection that may exist between
the site ground-water resources and the regional ground water systems existing in the valleys (Bureau
of Land Management, 1985a). These baseline studies were nor obtained for review and analysis in
this report.
Two wells, MW1 and MW3, drilled into the sedimentary Cambrian units downgradient of the current
tailings impoundment, were found to be dry. It is unclear if the Cambrian units may contain water in
other areas surrounding the facility. According to Colosseum personnel, further information on these
wells is not available.
It is unclear if water resources exist in small pockets of alluvium at the site. With the exception of
monitoring well MW2, a dry well installed downgradient of the tailings impoundment, no information
was obtained on wells that may have been completed in the limited alluvial deposits (see section
3.3.2).
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Site Visit Report: Colosseum Mine
Several springs, both perennial and intermittent, exist in the Colosseum Gorge, just east of the site.
Water quality of these springs is good; TDS concentration is approximately 550 mg/L The springs
yield only small amounts of water, ranging from 0.1 - 5.0 gpm; however, as discussed above, they
provide sufficient water to support intermittent streams and watering holes in the Colosseum Gorge.
(Bureau of Land Management, et al., 1985a) Figure 3-4, a topographic map of limited extent, shows
the location of several ground-water wells and springs.
As discussed above, there are aquifers in the valley surrounding the site. The Ivanpah Valley Aquifer
ranges from 20 to 220 feet below the surface of the valley. The total aquifer storage capacity has
been estimated by the California Department of Water Resources at 3,090,00 acre-feet, with an
annual recharge of approximately 800 acre-feet. According to the EIS, when the mine was originally
proposed, the Ivanpah Valley Aquifer was experiencing diminishing ground water levels, or
"overdrafts", as a result of annual ground-water extractions exceeding the annual recharge.
Colosseum maintains two wells in the Ivanpah Valley for water supply. These wells provide 800
gallons per minute, 16 hours a day (i.e., approximately 860 acre-feet per year). Consequently,
ground water extraction for Colosseum's operations may result in further ground water overdrafts in
the Ivanpah Valley Aquifer. Water quality of ground water in the aquifer is highly variable, ranging
from good to poor, and has been used in industrial, irrigation, domestic, and livestock operations.
Colosseum samples and analyzes the ground water extracted from their Ivanpah Valley Aquifer water
supply wells on a quarterly basis. Samples are collected at building taps. Table 3-1 presents a
summary of this water quality data.
The Shadow Valley Aquifer ranges in depth from 40-300 feet below ground surface. Total storage
capacity was estimated by the California Department of Water Resources as 2,130,000 acre-feet.
Ground water quality in the Shallow Valley aquifer is highly variable, with TDS values ranging from
500 - 2,400 mg/1 and poor quality water exiting from the local valley springs. During operations,
Colosseum extracted no water from the Shadow Valley Aquifer.
Depth to the Mesquite Valley Aquifer ranges from 20 to 200 feet. The California Department of
Water Resources estimated the aquifer storage capacity at 580,000 acre-feet. The water quality is
locally unsuitable for domestic and irrigation uses. During operations, Colosseum extracted rib water
from the Mesquite Valley Aquifer.
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Site Visit Report: Colosseum Mine
MBOHl
Q IPIIINO LOCATION
Figure 3-4. Locations of Wells and Springs Near the Tailings Impoundment and in
Colosseum Gorge
(Source: Steffen Robertson and Kirsten, 1987)
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Site Visit Report: Colosseum Mine
Table 3-1. Concentrations of Selected Constituents from Quarterly Samples of Ground Water
Extracted From the Ivanpah Valley Aquifer
Anajyte:... *.:;;'
Conductivity,
mmhos/cm
pH, s.u.
WAD CN, ppm
Total CN, ppm
TDS, ppm
Sulfate, ppm
Sodium, ppm
Copper, ppm
Iron, ppm
Zinc, ppm
Lead, ppm
: 1988*
Min. -Max.
697 - 709
8.0-8.10
< 0.005 - <0.02
< 0.005 - <0.02
313 - 350
37 - 47
47-57
<0.01 - <0.02
0.05 - <0.02
0.18-0.37
NS
1989
Min. -Max.
678 - 709
8.08-8.19
<0.02
<0.02
325-340
45-46
48-59
<0.02
0.05 - <0.01
0.05-0.17
< 0.002
1990
Min. - Max.
666 - 741
7.80-8.13
X0.02
<0.02
330-360
35-45
55-63
<0.02
<0.01
0.03-0.1
< 0.002
1991**
Min.- Max.
653 - 769
8.16- 8.48
<0.02
<0,02
350 - 360
43-47
59-63
<0.02
<0.01 - <0.04
0.02 - 0.9
< 0.002
KEY:
* 1988 data is for only two sampling events (two quarters).
** 1989 data is for only three sampling events (three quarters).
NS - No sample
Source: Colosseum, Inc., 1992.
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Site Visit Report: Colosseum Mine
3.2 FACILITY OPERATIONS
This section describes the extraction and beneficiation operations as they appeared during the time of
EPA's site visit at the Colosseum Mine in May of 1992. Since that time both the mine and mill have
ceased operation. During operation, the flow of materials began with the removal of waste rock and
ore from two open pits. The ore was either transported to the mill or stored in the low grade
stockpile. At the mill, the ore was crushed, ground and leached in a Carbon-In-Pulp (CIP) cyanide
circuit for the removal of precious metals. After stripping the precious metals from the carbon,
electro winning, electrorefining and smelting (in a small furnace), a dore of 70 percent gold and 30
percent silver was produced. A general site map illustrates the location of facilities described below
(see Figure 3-5).
3.2.1 Mining
Mining began at Colosseum in late 1987 and the mill began operating hi January 1988. In May 1992,
mining at the Colosseum Mine removed 15,000 tons of rock per day, five days a week. This rate
was down from the 29,000 tons of rock removed per day, six days a week hi 1990. The State
permitted the mine to excavate up to 31,000 tons per day. (Attaway, Undated)
The two breccia pipes (ore bodies) were mined through two open pit excavations: the North and
South pits. Colosseum used a contract mining company, Industrial Contractors Corporation, to drill,
blast, excavate and transport the waste rock and ore from the pits. Blastholes with a 6.5 inch-
diameter were drilled on a 15-foot by 15-foot square pattern using a downhole hammer. ANFO
(ammonium nitrate mixed with fuel oil) was used as the blasting agent. Four blasts were conducted
each week, with no more than one per day. A 13-cubic yard front-end loader excavated the broken
rock and placed it into 85-ton haulage trucks for transport to either the waste rock piles, the low-
grade stockpile (the waste rfcck /low-grade cutoff was not obtained), or the primary crusher. Fifty-ton
haulage trucks were used hi the South Pit due to the restricted access of the narrowed pit
configuration at the bottom of the pit (see section 3.3.3).
According to Colosseum, the project to date stripping ratio hi both pits was 3.97:1 (waste to ore). In
the South Pit, Colosseum maintained a 2:1 (waste to ore) stripping ratio. Colosseum reported a 6:1
stripping ratio on some 20 benches hi the South Pit (it is unclear how this ratio relates to the overall
South Pit ratio of 2:1). The stripping ratio hi the North Pit was 1:1 (waste:ore). The interslope
angle of the South Pit is 53 degrees. The interslope angle of the North Pit is 45 degrees. Twenty-
foot benches were maintained hi both pits. Safety benches were left every 60 feet in the South Pit
and every 40 feet hi the North Pit.
At the time of EPA's visit, the bottom of the South Pit was at an elevation of 5280 feet,
approximately 760 feet deep. Colosseum personnel estimated that continued mining hi the South Pit
will result hi a finished elevation of 5240 feet for the bottom of the South Pit. The mine
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Site Visit Report: Colosseum Mine
Figure 3-5. General Site Map of the Colosseum Mine
(Source: Colosseum, Inc., 1989a)
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Site Visit Report: Colosseum Mine
superintendent estimated the greatest distance across the South Pit to be 1600 feet. The EPA team
observed water in the bottom of the pit. According to Colosseum personnel, water is pumped to the
tailings impoundment from a sump in the bottom of the pit (no estimate was provided on the amount
of water encountered or the level at which water was first encountered). Ore removed from the South
Pit yielded approximately 80 ounces of gold per day (when higher grade ore was mined, yields were
up to approximately 200 ounces of gold per day). Mining in this pit was scheduled to end in June
1992.
The North Pit bottom was at an elevation of 5,740 feet with a depth of 300 feet at the time of EPA's
visit. Prior to 1991, the North Pit was used mostly as a "relief area," mined when the South Pit was
being drilled and blasted. In 1991, heavy mining began in the North Pit. According to Colosseum
personnel, ore removed from the North Pit yielded 40 to 60 ounces of gold per day. During the site
visit, Colosseum personnel estimated that mining would cease in the North Pit at the end of August
1992. On August 4, 1992, Colosseum notified EPA that mining had terminated in both pits on July
10, 1992.
3.2.2 Benefiriation
The beneficiation plant is designed for an ore throughput of 3,400 tons per day, or 1.2 million tons
per year. As of May 1992, the circuit was beneficiating 3,000 tons of ore per day. Milling
operations ceased on May 31, 1993. Figure 3-6 presents a map of the mill. Figure 3-7 illustrates
the flow of ore and materials through the entire beneficiation operation.
3.2.2.1 Crushing and Grinding
Ore is dumped out of the haulage trucks into a 185-ton hopper with a vibrating feeder. Oversize
material (greater than 6-inch) goes to the swing jaw crusher (48 inch by 60 inch) and undersize
material (minus 6-inch) goes to a conveyor for transport to the crushed ore stockpile. The jaw
crusher reduces the ore from a size of up to 3 feet to less than 6 inches. The crushed ore drops onto
the conveyor for transport to the crushed ore storage pile. The crushed ore stockpile contains a 10-
day supply for the Carbon-In-Pulp (CIP) plant, with a total capacity of 33,000 tons.
Water sprays are used to control dust at the 185-ton hopper when haulage trucks are dumping ore.
The ore crushing unit (including the vibrating feeder, the jaw crusher, the conveyors and the feeders)
is equipped with a wet scrubber to collect dust. Slurry from the wet scrubber is pumped to the
common mill discharge sump for mixing with the ore slurry. During EPA's visit, the jaw crusher
was not operating due to sampling of the wet scrubber. According to Colosseum, the testing of the
wet scrubber was for paniculate emissions levels and for lead concentrations in the emissions.
Three feeders beneath the stockpile convey ore at the rate of 150 tons per hour to the semi-
autogenous grinding (SAG) mill. As the ore is conveyed to the SAG mill, it passes under a lime «il<>
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Sire Visit Report: Colosseum Mine
Figure 3-6. Colosseum Mill Facility Map
(Source: Colosseum, Inc., 1989b)
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Site Visit Report: Colosseum Mine
Figure 3-7. Colosseum Mill Flow Chart
(Source: Bond Gold Colosseum, Inc., Undated)
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Site Visit Report: Colosseum Mine
where lime is added to the ore at the rate of two pounds per ton. The purpose of the lime addition is
to maintain a pH of 10.8 in the leach circuit. A baghouse is used to collect lime paniculate emissions
from the lime silo. The conveyor and grinding equipment are equipped with exhaust venting to a wet
scrubber. All storm water runoff from the pile and the immediate mill area is directed to the tailings
impoundment.
The SAG mill is rubber-lined and measures 21 feet by 13 feet. Water and ore are continuously added
to the SAG mill during operation. Grinding media, five-inch steel balls, are charged to the SAG mill
daily. The SAG mill grinds the ore to approximately 3/4-inch and maintains 70 percent solids by
weight hi the discharge slurry. The slurry exiting the SAG mill passes over a grate for the removal
of resistant pebbles. These pebbles are sent to a cone crusher for crushing with the crushed product
being conveyed back to the SAG mill.
*
The slurry passing through the grate enters the common mill sump where additional water is added.
The slurry is then pumped to a cyclone for sizing. Oversized material (greater than 80 mesh) is sent
to a 14- by 24-foot ball mill for additional grinding. The ball mill grinding media are abraded balls
from the SAG mill, typically two to three-niches in diameter, and new three inch balls. The ball mill
discharge slurry is about 76 percent solids by weight. In the ball mill, ore is ground so that 100
percent passes minus 80 mesh (the feed size for the CIP) and 80 percent passes 120 mesh before it
exits the ball mill into the common mill sump. The slurry hi the common mill sump is pumped to the
cyclone for sizing. Undersized material (approximately 18 percent solids) continues to the CIP, by
way of a thickener, and oversize material (i.e., over 120 mesh) is returned to the ball mill for further
grinding.
On its way to the thickener, the ore slurry passes over a trash screen, which removes oversized
material that has made it through the cyclone sizing operation. This material is typically wood and
paper, which makes it through the cyclones because of its low specific gravity. The "trash" is
returned to the tailings sump and disposed of as tailings. According to Colosseum, the amount of
"trash" is less than 0.01 percent of the tailings. The slurry enters the thickener along with a
flocculent, an anionic polymer, A-207. The thickener dewaters the slurry to approximately 56
percent solids by weight. Overflow (water) from the thickener is recycled into the mill makeup water
tank and the thickened slurry is typically pumped to a pre-aeration tank (tank 1) te oxidize any
sulfides present prior to entering the CIP tanks.
The SAG mill is powered by a 2,500 horsepower direct current variable speed motor for efficient
grinding. The Ball mill is powered by a constant speed 2500 horsepower alternating current motor.
The grinding units receive maintenance once per week with a complete lubrication. The rubber liners
in the SAG mill are replaced every four to six months.
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Site Visit Report: Colosseum Mine
3.2.2.2 Carbon-In-Pulp
Colosseum used the Carbon-In-Pulp technique to leach the precious metals from the ground ore
slurry. Ore slurry is pumped to a leach tank where sodium cyanide (NaCN) is added and the slurry
is agitated. This cyanide/ore mixture is pumped to the first tank and then gravity flows through a
series of tanks for the recovery of the precious metals. Activated carbon is transferred by airlifts
through the tanks countercurrent to the flow of the ore/cyanide slurry. Gold and silver cyanide
complexes adsorb on the carbon, creating loaded carbon at the front of the circuit. At Colosseum,
the circuit maintains a constant ore/cyanide slurry flow of 700 gallons per minute. Tank 1 (130,000
gallon capacity) is normally the first tank in the leach circuit. Compressed air is sparged into the
slurry to enhance dissolved oxygen content. The total sulfur content of the ore processed is kept at
less than 2.5 percent to limit oxygen consumption. Tank 1 was not in use at the time of EPA's visit
due to a change in the sulfide content of the mined ore. During normal operation, slurry from tank 1
gravity flows to tank 2, where IS percent sodium cyanide (NaCN) is added; tank 2 is agitated. Since
tank 1 was not in use during the site visit, tank 2 was the first step in the CIP operation at that time.
This tank is sampled every 2 hours and cyanide content is maintained at 0.6 pounds per ton of
solution, the optimal concentration for leaching the ore.
There are seven steel CIP tanks, numbered three through nine. The leached slurry is pumped into
tank number 3 and leaves through tank 9. At the same time, coarse carbon gravity flows into tank 9
and travels toward tank 3, countercurrent to the slurry flow. Each tank holds 130,000 gallons of ore
slurry and six tons of carbon. The carbon is advanced from tank to tank by airlifting the slurry to
external screens that discharge the carbon to the preceding tank. Compressed air is bubbled along
screens hi the tanks to aid circulation by inhibiting screen blinding. The ore slurry gravity flows to
the next tank. The ore slurry has a 24-hour residence time for the entire circuit. The gold
concentration of the slurry, initially 2.0 to 2.5 ppm in the first tank, drops to less than 0.01 ppm in
the final tank as it is adsorbed by the carbon. The spent ore slurry (tailings) gravity flows to an
aeration tank, tank 10, for a final screening of any carbon that may have become inadvertently
entrained in the spent ore. Tailings, containing approximately 260 ppm weak acid dissociable (WAD)
cyanide, gravity flow from the aeration tank to tank 11 for cyanide destruction using the INCO SO2
Process (see section 3.3.1). In 1991, 928,444 tons of ore were leached hi the CIP circuit.
All tanks hi the CIP circuit are surrounded with secondary containment. According to facility
personnel, the secondary containment has sufficient capacity to handle "all spills", but the exact
volume of secondary containment was not obtained. Any spillage is reportedly pumped back into the
process tanks.
3.2.2.3 Carbon Stripping
Loaded carbon containing as much as 120 troy ounces of gold per ton of carbon, is pumped in
batches from the CIP tanks to a stripping column. The stripping column is a 20-foot tall, rubber-
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Site Visit Report: Colosseum Mine
lined steel tank with a capacity of 3.8 tons. A solution of 1.5 percent cyanide and one percent caustic
(sodium hydroxide) is heated to 240°F and circulated in the stripping column (the pH of this solution
and its method of heating was not obtained). This stripping solution creates a chemical environment
that favors the dissolution of gold from the carbon and the creation of gold cyanide complexes. When
the stripping cycle is complete, the pregnant solution, containing approximately 250 ppm gold, is sent
to a pregnant solution tank. It is unclear how long the carbon stripping cycle takes to remove the
gold/cyanide from the carbon.
At the end of the stripping cycle, the carbon contains four troy ounces of residual gold per ton. A
hydrochloric acid solution (concentration of hydrochloric acid was not obtained) is used to clean the
carbon before it is regenerated and sent back to the CIP circuit. Carbon fines collected from the
regeneration operation are currently stored on-site, but will be sent to an off-site smelter for the
recovery of residual precious metals after die mill closes. Approximately 0.035 pounds of carbon per
ton of ore leached are lost to attrition. Further information about the disposition of the acidic
cleaning solution or the carbon regeneration operation was not obtained.
3.2.2.4 Electrowinning, Electrorefining, and Smelting
The company uses electrowinning to recover the gold from the pregnant solution. Pregnant solution
is pumped from the pregnant solution tank to two parallel 32-cubic-foot cells, and circulated at a rate
of approximately 20 gallons per minute. As the solution circulates through the electrowinning cells,
gold is precipitated onto steel wool. Residence time for the pregnant solution is up to 19 hours or
until the gold concentration in the solution falls below 20 ppm. The now barren solution is recycled .
to tank 2, the leach tank.
The gold-laden steel wool cathodes are transferred from the electrowinning cells to a 32-cubic-foot
electrorefining cell containing stainless steel plates and filled with electrolyte containing five percent
sodium cyanide and 1.5 percent sodium hydroxide recirculated at 50 gallons per minute. The polarity
is reversed and gold on the steel wool is plated onto the stainless steel sheets. Residual gold also
accumulates on the bottom of the cell as gold sludge. Gold is scraped from the plates and the bottom
of the cell and sent to the furnace for melting. The gold furnace is operated two or three times per
week. According to Colosseum, the use of chemicals in the electrorefining operation is according 10
strict procedures. All spent solutions are recycled or returned to the mill circuit as chemical additions
to assist hi gold extraction.
The furnace is charged with gold foil and gold sludge, and borax, silica, and potassium nitrate, which
are used as a flux. The furnace has an exhaust hood that leads to a high stack operating with no
scrubber or emission control device. The furnace is powered by clean burning propane. According
to Colosseum, furnace stack emissions were reviewed by the Air Pollution Control District and no
emission control device was deemed necessary. /The furnace stack was given the identification
number 08004 during the 1989 Air Toxics Emission Inventory. No further information was obtained
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Site Visit Report: Colosseum Mine
on the operation of the furnace used to melt the gold and pour dor£ bars. According to Colosseum
personnel, slag from the melting and pouring operation is first panned for coarse gold and then sent
back to the SAG mill. The dorg, averaging 70 percent gold and 30 percent silver, is sent to several
different off-site refiners. In 1991, 61,553 troy ounces of gold were poured. Recovery of gold from
ore averages 92 percent in the CIP/electrowinning circuit.
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Site Visit Report: Colosseum Mine
3.3 MATERIALS AND WASTE MANAGEMENT
The following section describes the specific wastes and materials generated and managed at the
Colosseum Mine. Wastes managed pn-site include waste rock and tailings, also called spent ore,
from the CIP operation. In addition, other materials not typically considered wastes, such as mine
water and low-grade ore, are managed on-site during the active life of the facility. Because these
materials ultimately become wastes when intended for disposal (e.g., at closure of the facility), they.
are also addressed in this section. Figure 3-8 illustrates the life-of-mine statistics on waste rock, ore,
and gold.
3.3.1 Waste Rock Piles
Colosseum has been removing waste rock from the two pits since the commencement of mining in
1987. The years 1988, 1989 and 1990 witnessed the greatest rate of waste rock generation at th^site.
Over these three years, approximately 23 million tons of waste rock were excavated and placed,in
piles onsite. In 1991, approximately two million tons of waste rock were removed from the two open
pits. Colosseum has tested waste rock material using the acid-base accounting method for
determining acid generating potential. According to Colosseum, results indicate that waste rock is not
acid generating.
Waste rock excavated from the two open pits is disposed of hi four different waste rock dumps.
According to the Draft EIS, these waste rock piles were designed to cover 130 acres and
accommodate up to 40 million tons of rock at the conclusion of mining. These four waste piles,
designated as the East, West, North and Southwest piles, were formed by trucks dumping material
into small ephemeral drainages adjacent to the two mine pits (see Figure 3-5). Most haulage distances
are less than one-half mile. No liners underlie the waste piles and the dumps rest upon Precambrian
crystalline rocks (see section 3.4.3). The mine dumps exist at their natural angle of repose (specific
angle was not obtained), but are graded on occasion to provide access and to maintain the waste dump
surface for receiving rock. Information on runoff controls at the waste rock piles was not obtained.
The current volume of rock contained hi the waste piles and the height and size of the dumps was not
obtained. The planned heights and elevations of each waste rock pile were included hi the Draft EIS
as follows: West dump would extend from an elevation of 5,250 feet above sea level to an elevation
of 5,860 feet above sea level (total height of 610 feet), East dump would extend from an elevation of
5,435 feet above sea level to 5,920 feet above sea level (total height of 495 feet), Southwest and
North dumps would range between 300 and 400 feet in height (Bureau of Land Management, et al.,
1985a). No underdrain or sediment collection dams were proposed for these piles, according to the
EIS. The EIS presented the following rationale for this decision (Bureau of Land Management, et al..
1985a):
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Site Visit Report: Colosseum Mine
TONS MILLIONS
GOLD (THOUSANDS)
1987 1988 1989 1990 1991 1992 1993
ORE MINED
ORE MILLED
WASTE MINED
OUNCES POURED
Figure 3-8. Life of Mine Statistics
o
(Source: Colosseum Inc., Undated)
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Site Visit Report: Colosseum Mine
The slope of the waste rock surface will direct storm water runoff flow back toward the
open pits;
Due to low annual precipitation and high annual evaporation, percolation of storm water
runoff is unlikely, and; "
In the event of storm water infiltration, any leachate created would contain the same
compounds as the surrounding host rock; no sulfides were to be disposed of in the waste
rock piles.
According to Colosseum personnel, at the end of mining, the waste rock piles will be graded to
eliminate any "mesa-like" appearance. Original closure plans included the installation of two ground-
water monitoring wells downgradient of the waste rock piles. However, since the site visit,
Colosseum has indicated that they do not intend to install the monitoring wells. No additional
information was provided.
3.3.2 Low-Grade Stockpile
At the time of EPA's visit, the low-grade stockpile contained 1:3 million tons of ore (a one year
supply) grading 0.033 troy ounces of gold per ton (the lower grade cutoff between waste rock and
low-grade ore was not determined, nor was the low-grade/high-grade cutoff). According to
Colosseum personnel, this ore will be milled at the close of mining and no reclamation effort will be
necessary. The stockpile area will be recontoured, topsoil added if available, and revegetated. No
information was obtained about the construction of the pile. According to Colosseum, storm water
runoff from the stockpile area is directed to the tailings impoundment. (It is not known if this
stockpile was milled prior to closing the mill in May of 1993.)
3.3.3 Open Pits
According to Colosseum, mining of either pit is no longer economically feasible. However, given an
increase hi the price of gold, mining could resume. As a result, the two open pits have remained
since mining ceased in July, 1992. As noted previously, the final depth of the South Pit is estimated
to be 800 feet (no final depth was obtained for the North pit). Maps of the ore body indicate that
abandoned underground workings were present in the South Pit prior to open pit mining (these
workings are presumably the old Colosseum Mine) (Bureau of Land Management, 1985a). The EPA
team did not observe adit or shaft openings in the walls or floor of the South Pit.
As noted in section 3.2.1, ground water discharges at a low rate into the pit bottom. The
Reclamation Plan notes that a permanent pool of water (from ground water discharges or surface
water runon) is not anticipated to collect in either pit. The perimeter of the pit is to be graded or
bermed to intercept and divert runoff. According to the Reclamation Plan, any ground water which
collects in the pit is expected to evaporate (Bond Gold Colosseum, Inc., Undated). No contingency
plans were included hi the .Reclamation Plans in the event witer formed an intermittent or permanent
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Site Visit Report: Colosseum Mine
pool in the pit. No further reclamation of the .pits is anticipated with the exception of fencing and the
posting of signs warning of potential danger to trespassers (Bond Gold Colosseum, Inc., Undated).
According to Colosseum, the South Pit currently has standing water in the bottom, which was not
anticipated during project planning. The Colosseum Mine is now conducting a ground water study,
and will continue to work with the State Water Quality Control Board to develop a closure plan for
the South Pit.
3.3.4 Cyanide Destruction Reactor
Colosseum uses the International Nickel Company (INCO) SO2 cyanide destruction process to
decompose free and complexed cyanide species in the tailings slurry. The INCO process injects SO2
and air into a well-agitated vessel to oxidize cyanide in the tailings slurry and create inert cyanate
complexes. At Colosseum, the solution is mixed with a 250 horsepower agitator as 2,000 standard
cubic feet per minute of low pressure air is injected into the tank. Because acid is produced in the
oxidation reactions, lime is added to the reaction tank to maintain a pH range of 8.5 to 9.0. Copper
sulfate may be added to act as a catalyst for the oxidation reactions.
The tailings typically contain 50 percent solids by weight and 225 ppm WAD cyanide. Tank 11, a
13,025 cubic foot (100,000 gal) reactor tank, detoxifies tailings from the aeration tank in the CEP
circuit in approximately 2.3 hours. A 2.3 hour residence time in a 100,000 gallon tank maintains a
flow rate of 724 gpm, similar to the CIP flow rate. According to Colosseum, the final total cyanide
concentration of the tailings slurry is less than 1.0 ppm. Detoxified slurry flows to the tailings sump
and is tested every two hours for WAD cyanide. As required by Colosseum's waste discharge
requirements, Colosseum collects at least three samples of tailings slurry per day to make one
composite sample. The tailings slurry composite sample is separated into a solid fraction sample and
a liquid fraction sample for analysis. These are shipped to an independent lab for total cyanide
content analysis (see section 3.4.3). (Colosseum, Inc., 1992d)
3.3.5 Tailings Impoundment
Tailings from the INCO process are sent to a tailings sump at the mill which drains to the tailings
impoundment via a pipeline (information on the tailings sump and pipeline was not obtained). Before
designs, for the tailings impoundment and cyanide destruction system were approved, Colosseum
conducted a pilot program to determine the final composition of the tailings before cyanide destruction
(details of the pilot program were not available) (Bureau of Land Management, et al., 1985a). Tables
3-2 and 3-3 present the analytical results of tailing samples created in the pilot program. Table 3-1
presents a comparison of the estimated composition of tailings liquid (prior to cyanide destruction i a»
determined in the pilot tests and the actual composition of tailings liquid (after cyanide destruction) a»
sampled and analyzed throughout the life of the mine.
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Site Visit Report: Colosseum Mine
Table 3-2. Chemical Analysis of Tailings Solids - Common Mineral Components
(Unprocessed Ore Analysis)
»JLl " "' '' * "
Parameter
Silicon Dioxide
Titanium Oxide
Aluminum Oxide
Ferric Oxide
Manganous Oxide
Magnesium Oxide
Calcium Oxide
Sodium Oxide_
Potassium Oxide
Phosphorus Pentoxide
Total
Concentration (percent)
75.90
0.06
12.40
0.61
0.03
0.17
* 0.16
0.21
8.51
0.09
98.14
*
KEY: * Loss on ignition accounts for an additional 1.16 percent.
Source: Bureau of Land Management, et al., 1985a.
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Sire Visit Report: Colosseum Mine
Table 3-3. Minor and Trace Constituents of Colosseum Tailings Solids
Parameter
Antimony
Arsenic
Barium
Ceryllium
Cadmium
Chromium (total)
Cobalt
Copper
Lead ,
Mercury
Molybdenum
Nickel
Selenium
Silver
Vanadium
Zinc
Thallium
Concentration (mg/kg)
<0.05
29.00
13.00
0.44
4.30
6.70
, 5.50
158.00
158.00
0.01
1
1.50
4.80
0.15
0.27
2.80
868.00
<1.00
Source: Bureau of Land Management, et al., 1985a.
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Site Visit Report: Colosseum Mine
Table 3-4. Comparison of Original Estimate of Tailings Liquid Composition and
Actual Annual Tailings Water Analyses
. PttFunettr
Cond, nunhos/cm
Ph. su
WADCN, ppm '
Total CN, ppm
Free and WAD
Cyanide, ppm
IDS, ppm
Sulfote, ppm
Sodium, ppm
Copper, ppm
Iron, ppm
Zinc, ppm
Lead, ppm
"Estimated* '
ComposftioB
NA
NA
NA
NA
106
NA
700
2,200
52.8
39.4
31.9
NA
198$**
6,540
8.39
0.00
0.01
NA
5,100
3,300
670
0.36
0.11
0.0
NA
1$89**».
Mln - Max
7,110-9,210
6.6-8.7
0.0-0.8
0.21-0.45
NA
4',800-6,183
2,700-4,100
490-880
0.0-1.6
0.00
0.11-2.5
NA
1SW**
Min-Max
3,320-7,440
8.24-8.82
0.02-0.17
0.02-0.26
NA
2,300-5,500
1,400-3,800
260-760
0.22-2.8
0.00
0.08-0.25
<0.002-0.003
tw***
Min-Max
5,720-7.670
8:24-8.48
0.07-0.14
0.03-0.18
NA
3,600-5,600
1,800-3,500
370-750
0.09-1.7
0.00-<0.1
0.02-0.12
< 0.002-0.01
KEY: * - Data are from the Draft EIS, based on laboratory pilot tests of the ore.
** - Data presented for 1988 are from one quarter.
*** - Data presented for 1989,1990 and 1991 are maximum and minimum values from quarterly
sampling events.
NA - Not Available
ppm - parts per million
su - standard units
mmhos/cm- micromhos/centimeter
Source: Colosseum, Inc., 1992; Bureau of Land Management, 198Sa.
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Site Visit Report: Colosseum Mine
The tailings impoundment occupies the head of a canyon, approximately one-half mile south of the
mill site (see Figures 3-4 and 3-5). The impoundment began receiving tailings in 1988. The native
ground at the tailings impoundment location consists of shallow alluvial deposits covering
Precambrian gneisses. As required by the reclamation plan for Colosseum, topsail in the area to.be
occupied by the tailings impoundment was removed and stockpiled around the tailings impoundment
(no further information was obtained on the topsoil stockpiles) (see section 3.4.1).
The tailings dam was constructed on top of a compacted foundation soil overlying Precambrian
bedrock. A rock core was emplaced over the foundation soil and covered with compacted fill. The
dam was designed to be raised by lifts (as production required) to a final design elevation of 5,375
feet above sea level. The impoundment created behind this dam would cover 150 acres and contain
precipitation and runon from a 10,000 year, 24-hour storm event. The dam was also designed to
withstand the Maximum Credible Earthquake (see section 3.1.4). Two small retention dams were
also constructed along the perimeter of the tailings pond to prevent overflow into areas outside the
tailings impoundment. An emergency spillway was constructed hi 1991 on the northwest boundary of
the tailings impoundment (Bureau of Land Management, 1985a; Colosseum, Inc., 1991). The
emergency spillway was part of the original design and was constructed to handle the runoff from the
PMF after the tailings area has been reclaimed. Waters overtopping the spillway would flow to the
dry drainage below the tailings impoundment (the elevation of this spillway was not available). The
approved reclamation plan required the construction of diversion channels for any ephemeral streams
located in the tailings impoundment area if the tailings dam was not designed to store runoff from the
Probable Maximum Flood (PMF) (it is unclear what recurrence interval was determined for the PMF
storm). According to Colosseum, since the tailings dam was designed to store the runoff from the
PMF, no diversion channels are required.
Green's Well (a livestock watering well) and mine shafts leading to abandoned underground tungsten
workings in Precambrian gneisses, were hi the middle of the proposed tailings impoundment location.
As a condition of Colosseum's waste discharge requirements, these shafts and tunnels were to be
backfilled and sealed to prevent discharges of tailings water into the ground water (see section 3.4.3).
Information on the methods used to backfill and seal these openings was not obtained.
t
As of December 1991, 4,805,250 tons of tails had been placed into the impoundment. Tailings are
piped from the mill to a distribution pipeline that encircles the impoundment and discharged through
subaerial deposition. Subaerial deposition of tailings produces a maximum density tailings, while
providing reclaim water by avoiding excess interstitial water in the tails. According to Colosseum
personnel, the dam was raised to a crest elevation of 5,341 feet above sea level in 1991 and it is
anticipated that no further raising of the dam will be necessary before reclamation begins. During the
site visit, the dam appeared to be about 100 feet high. According to Colosseum personnel, the
current impoundment will contain the precipitation and runon from the 1,000 year, 24-hour storm
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Site Visit Report: Colosseum Mine
event and it is now approved to store tailings to elevation 5,336 feet above sea level, with a final
freeboard of five feet. .
According to Colosseum personnel, the 17 inches per year in evaporation results in a net deficit of
available water for the mine. Tailings water is reclaimed off the pond and pumped to the mine's
process water tank. Ten piezometers placed along the downstream face of the dam record water
levels in the core to ensure the correct functioning of the dam. (Colosseum, Inc., 1992b).
The tailings impoundment is unlined and an underdrain system collects tailings dam seepage and
conveys the liquid to two ponds located downstream of the dam (size and capacity of the ponds was
not obtained). Seepage enters the ponds at an average rate between SO and 90 gallons per minute
(variability is seasonal) and is pumped back to the tailings impoundment. According to Colosseum
personnel, seepage in the first year of operation was at a rate greater than the pumping system could
maintain. The underdrain system is valved and the flow was restricted to the pump capacity for the
first year of operation. The tailings subsequently sealed die impoundment as designed and the flow
has slowed to current levels. According to Colosseum, there was no discharge. The two seepage
collection ponds are double-lined with 40-mil high density polyethylene (HDPE) liners. A leak
detection system, consisting of geotextile fabric, six niches of sand and a network of perforated pipe
draining to an inspection sump, was installed between the liners of each pond. The leak detection
system is required to be checked visually each month, and, if liquid is present, a sample must be
collected and analyzed for the parameters listed hi the Monitoring and Reporting Program No. 87-20
for the Colosseum Gold Mine (see section 3.4.3) (California Regional Water Quality Control Board,
Lahontan Region, 1987a; 1987b).
Several monitoring wells have been installed in the tailings impoundment area. Figure 3-4 illustrates
the location of these monitoring wells. Five of these wells (MW4, MW5, West, South and Gorge
Wells) are sampled on a quarterly frequency. Wells MW1, MW2 and MW3 were installed
downgradient of the tailings impoundment and completed in Cambrian sedimentary units, alluvium
and Precambrian gneiss, respectively (Sergent, Hauskins and Beckwith, Undated). According to
Colosseum personnel t these latter three wells were dry upon completion and have never contained
water. Monitoring results indicate that the tailings water may be migrating toward the West well.
However, according to Colosseum, current studies may indicate that sulfate levels may not be the
result of the tailings water. Colosseum, in cooperation with the State Water Quality Control Board, is
conducting further studies to research this issue. Further information, including monitoring results.
are presented in section 3.4.3.
Reclamation on the tailings impoundment will begin after all stockpiled ore has been leached in the
CIP circuit, probably sometime in 1994. The approved reclamation plan for the tailings impoundment
requires the following elements:
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Site Visit Report: Colosseum Mine
Cover downstream slope of tailings dam with mine waste rock to minimize erosion.
Reestablish vegetation through natural processes;
Cover top of tailings impoundment with mine waste rock or salvaged topsoil (to the extent
available). Grade top of tailings to direct surface runoff and prevent long-term ponding of
precipitation. Reseed with indigenous plants or plants established successfully in a similar
environment. Construct berms on the impoundment to discourage entrance. During the
site visit, EPA viewed an experimental garden of transplanted indigenous plants. Certain
species appeared to have made a successful transplant.
Maintain seepage ponds for several years; and
Retain diversion channels, if constructed around the tailings impoundment.
33.6 Other Wastes and Materials Reused/Recycled
Waste oil generated at the mine is collected by a contractor every ninety days for off-site recycling.
The name of the contractor was not obtained. No information was obtained on the quantity of waste
oil generated. Other oil/lubricant-contaminated wastes generated at the mine include: soil (from
minor spills), oil filters, and rags contaminated with used motor oil, used crater grease (from axle
lubrication) and empty 55-, 15- and 5- gallon drums/pails with residual crater grease/motor oil (from
lubricating operations). Specific quantities of these wastes were not obtained. These wastes are
collected by Disposal Control Services and shipped off-site for disposal.
In 1991, Colosseum generated a wide variety of wastes at the laboratory and mill. Assorted wastes
generated in the laboratory and mill, including borax, fiocculent, fluorospar, paint and rubber cement,
were collected and hauled off-site for disposal by Disposal Control Services (volumes of these wastes
were not obtained). Colosseum annually generates approximately 1.5 barrels of lead-contaminated
cupels from the fire assay process. Spent solvents are also generated (specific amounts were not
obtained). All of these wastes are picked up and transported off-site for disposal by Disposal Control
Services.
Spent electrowinning solutions are brought back to strength and reused. Spent carbon is regenerated
and reused. Spent carbon stripping solutions are used as cyanide addition to tank 2. The CIP tanks
are periodically drained and checked. The tanks are hosed clean and all residue is'milled for
contained gold. The ore slurry "trash" is treated as mill tailings. No information on the quantities of
these wastes generated was obtained.
Paper and trash are hauled by Desert Disposal Services to a landfill in Barstow. Sanitary sewage is
discharged to a septic tank at the mine (location of the septic tank was not obtained).
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Site Visit Report: Colosseum Mine
3.4 REGULATORY REQUIREMENTS AND COMPLIANCE
Colosseum is subject to both Federal and State regulatory requirements and their attendant permits.
Two statutes, the National Environmental Policy Act and the California Environmental Quality Act,
require that the proposed action (the mine operating plan) and alternative actions (i.e. alternatives to
the plan) be evaluated for their environmental consequences. Because portions of the mine are '
located on lands administered by BLM in San Bernardino County, the BLM was designated the lead
agency for NEPA compliance. The County was designated as the lead agency for CEQA (the County
is also the permitting agency for reclamation and air pollution control as designated by the State).
Through a Memorandum of Understanding among these two agencies and Colosseum, an
Environmental Impact Report/Environmental Impact Statement (EIR/EIS) was prepared and approved
for the Colosseum Mine.
*
3.4.1 Bureau of Land Management
As noted previously, the Colosseum mine site lies almost exclusively on Federal lands administered
by the Bureau of Land Management. Mining on these lands is subject to regulations set forth in 43
CFR Part 3800, "Mining Under the General Mining Laws." These regulations were promulgated by
the Bureau of Land Management under authority of the Federal Land Policy and Management Act
(FLPMA). The regulations provide BLM with the authority to approve a Plan of Mining Operation
on Federal Lands prior to commencement of operations, to require bonding, and to inspect mining
operations to ensure the operator is complying with these regulations (45 FR 78902).
Pursuant to these regulations, the Colosseum mine submitted a Plan of Operations to BLM and the
County of San Bernardino for approval (see section 3.4.2). Included as part of the mine operating
plan is a reclamation plan that describes the planned activities before, during, and after the operation
which will ensure the stabilization and reclamation of areas disturbed by mining.
Upon approval of the mine operating plan, Colosseum furnished to BLM (jointly with the State of
California Department of Conservation, Division of Mines and Geology) a stand-by letter of credit
(from the Royal Bank of Canada) to cover the cost of reasonable stabilization and reclamation of areas
disturbed by mining at the Colosseum site. The letter of credit is in the amount of $762,181 and was
to expire in February 1993 (Royal Bank of Canada, 1992). The bonding amount is reviewed yearly
and adjusted as deemed necessary by the BLM and the State.
A list of mitigative measures was developed for the EIR/EIS. These were incorporated into the
Operating Plan. These measures include:
* Elevate fresh water pipeline to allow unrestricted movement of the desert tortoise (an
endangered species which lives hi Ivanpah Valley)
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SUe Visit Report: Colosseum Mine
Apply dust suppressant on access road (Colosseum uses water soluble lignin sulfonate)
twice a year
Limit traffic on the mine access road (Colosseum provides transportation for employees in
a 15-passenger van from Las Vegas to the mine)
* Purchase and set aside desert land suitable as tortoise habitat to mitigate loss of 10 acres of
habitat caused by access road
Install wildlife troughs
* Treat fresh rock surfaces (road cuts) with "Eonite" (which mimics desert pavement through
a chemical reaction with rock)
Fence around tailings impoundment
i
Paint buildings to blend in with the environment.
The BLM (Needles Resource Area) inspects the Colosseum mine monthly to ensure compliance with
the approved mine operating plan.
3.4.2 California Department of Conservation, Division of Mines and Geology
The California Department of Conservation, Division of Mines and Geology, provides technical
support for the lead agencies (i.e., counties or cities) with responsibility for enforcing the
requirements of the State's Surface Mining and Reclamation Act (SMARA). For Colosseum, the lead
agency is the County of San Bernardino. The State legislature passed SMARA in 1975 to ensure that
minded lands in California are reclaimed. SMARA is triggered when a mine disturbs over one acre
of land or produces over 1,000 cubic yards of waste/ore per day. Regulations for the implementation
of SMARA were promulgated under California Code of Regulations, Title 14, Chapter 8, Subchapter
1, Article 1. Surface Mining and Reclamation Practice. The most significant reclamation
requirements outlined hi this regulation is the submittal of a reclamation plan to the lead agency by
the mining facility. Upon approval of the plan, the lead agency issues a permit to the facility to
operate. A reclamation plan for the Colosseum Mine was submitted to the County of San Bernardino
for approval hi conjunction with the development and approval of the EIR/EIS.
Although the County of San Bernardino was identified in the EIR/EIS as the lead agency for the
State, the Division of Mines and Geology is the beneficiary (jointly with BLM) of the stand-by letter
of credit provided by Colosseum to insure the performance of reclamation activities (Royal Bank of
Canada, 1992). The County inspects the mine yearly for compliance with the approved reclamation
plan.
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Site Visit Report: Colosseum Mine
3.4.3 California Regional Water Quality Control Board, Lahontan Region
The California Regional Water Quality Control Board also is responsible for regulating discharges of
mine wastes to land under the California Code of Regulations Title 23, Chapter 3, Subchapter 15,
Article 7, Discharges of Waste to Land. These regulations require that facilities discharging waste to
land submit a report of this discharge to the Regional Board. Upon receipt of the report, the Board
reviews the information, classifies the wastes and issues waste discharge requirements to the facility in
the form of a Board Order.
/
The Colosseum mine, as a gold cyanide mill, is subject to the zero discharge requirements of 40 CFR
440(j): that is, it may not discharge mill effluent (including tailings) to waters of the United States.
Thus, no NPDES permit has been issued to the facility by the Lahontan Regional Water Quality
Control Board.
Colosseum is not authorized to discharge to surface waters but two wastes generated at the Colosseum
mine are subject to the requirements of State regulations: tailings and waste rock. The Lahontan
Region Board classified the tailings produced at Colosseum as Group B wastes. These wastes are
defined as wastes that consist of or contain hazardous wastes that qualify for a variance under Section
66310 of Title 22 of this code, or wastes that consist of or contain nonhazardous soluble pollutants hi
concentrations that exceed water quality objectives for, or could cause degradation of, waters of the
state. The Board exempted these wastes from the liner requirement, based on a geotechnical report
prepared for the project that indicates that only limited amounts of groundwater underlie the project
site and that hydraulic interconnection between the project site and major aquifers (Ivanpah and
Shadow Valley) appears to be limited. (This report was not obtained). However, additional
monitoring requirements were included in the permit to provide early detection of wastewater
migration.
The waste rock was classified as a Group C waste by the Lahontan Regional Board. These wastes are
defined as wastes which would be in compliance with the applicable water quality control plan,
including water quality objectives, other than turbidity. No liner is required for disposal areas
receiving Group C wastes.
Colosseum operates under the California Regional Water Quality Control Board, Lahontan Region
Board Order No. 6-87-20, Revised Waste Discharge Requirements for Colosseum Gold Mine, San
Bernardino County, California and the accompanying Monitoring and Reporting Program No. 87-20
for the Colosseum Gold Mine, San Bernardino County, California. The Order prohibits the discharge
of any detoxified wastewater, waste rock or detoxified tailings slurry except into an authorized
disposal site. Further, the Order limits the concentration of cyanide (total and WAD) in tailings
discharged to the tailings impoundment. Total cyanide may not exceed 1.0 mgA and WAD cyanide
may not exceed 0.5 mg/1 hi the liquid tailings fraction, as averaged over a period of 30 consecutive
sampling days. For the solid fraction, total cyanide may not exceed 18.0 mg/kg and extractable total
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Site Visit Report: Colosseum Mine
cyanide may not exceed 0.5 mg/1. The Order also contains a (standard) narrativc'requirement that
discharges to the waters of the State shall not contain substances in concentrations that are toxic to, or
produce detrimental physiological responses in humans, plants, animals, or aquatic life.
In addition to the effluent limitations specified in the waste discharge requirements, the Order contains
requirements and prohibitions for specific components at the site as well as general requirements and
prohibitions. These include:
3.4.3.1 Cyanide Detoxification Facility (INCO)
' Effectively seal all cyanide leaching facilities (including leaching tanks and collection
ponds), to prevent the exfiltration of any liquids used in the extraction or detoxification
processes
3.4.3.2 Tailings Impoundment
Provide seepage detection systems on collection ponds
Construct the collection ponds and tailings impoundment in compliance with the
requirements for Group "B" mining wastes, except as allowed for the tailings
impoundment (i.e., the waiving of liner requirements)
Discontinue use of seepage collection pond and tailings impoundment upon presence of
liquid (containing in excess of 0.2 mg/1 free cyanide) in the leakage detection system
Cease discharge of tailings to the impoundment hi the event free cyanide (exceeding 0.2
mg/1) or any other monitored parameter exceeding 20 percent of background
concentrations are detected hi ground water or surface water outside the boundaries of the
tailings impoundment
Backfill and seal as necessary, all adits and/or tunnels located within the tailings
impoundment site, to prevent discharges of tailings water directly into the groundwater
Discharge, bypass, or divert no cyanide leaching solution, neutralization water, or tailings
slurry from the collection, transport, treatment or disposal facilities to adjacent land areas
or surface waters
Discharge no surface flow of any leaching solution, neutralization water, or tailings slum
from the authorized disposal sites to adjacent land areas or surface waters
Construct the tailings impoundment and waste rock disposal areas to protect against
overflow, washout, inundation, structural damage or a significant reduction in efficiency
resulting from precipitation and peak surface runoff flows from the 100-year, 24-hour
storm event
Maintain a vertical distance between the liquid surface elevation and the lowest point of t
pond dike or invert of an overflow structure of at least 2.0 feet
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Site Visit Report: Colosseum Mine
3.4.3.3 Waste Rock Piles
Construct the waste rock piles in compliance with the for Group "C" mining wastes.
3.4.3.4 General Requirements .
Cause no pollution or threatened pollution from the discharge (to land)
, i
Cause no nuisance in the treatment or discharge of waste
Comply with the engineering plans, specifications, and technical reports submitted with the
completed report of waste discharge
Dispose of all cyanide-contaminated waste materials, other than tailings, at a Class I
disposal site or neutralize and discharge at a Class IE disposal site,
Store all hazardous material containers in a secured storage facility that is not susceptible
to the elements, vandalism or potential public contact
Post signs warning the public of the presence of cyanide.
Several other provisions were included in the Order, including the submittal of a final closure plan
180 days prior to beginning any partial or final closure activities or at least 120 days prior to
discontinuing the use of the site for waste treatment, storage or disposal. One of the more important
provisions of the Board Order is the required compliance with Monitoring and Reporting Program
No. 87-20.
The monitoring and reporting program establishes the requirements for water quality monitoring and
reporting with respect to the discharge of waste to land at Colosseum. The program requires the
recording of information, the sampling and analysis of liquids, ground water, surface water and the
quarterly reporting of the information and results of the analyses. Pursuant to the program,
Colosseum records a number of production statistics, including the total quantity of ore processed, the
total quantity of detoxified tailings discharged to the tailings impoundment, and the total quantity of
waste rock placed at each of the four dump sites (a report containing all of this data was not
obtained).
As discussed in section 3.3.1, Colosseum is required to collect two composite samples daily
(composites of three individual samples) of the solid and liquid fractions of the tailings slurry. Both
the solid and liquid fractions are to be analyzed for total dissolved solids (reported in mg/1) and total
cyanide (reported in mg/1). The liquid fraction has to be analyzed for WAD cyanide (reported in
mg/1); the solid fraction has to be analyzed for extractable cyanide (reported in mg/1).
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Sire Visit Report: Colosseum Mine
The tailings impoundment return water must be sampled weekly (one grab and one 24-hour
composite) and analyzed for TDS, total cyanide and WAD cyanide. Results of these analyses were
not obtained.
Ground water monitoring requirements also are-included hi the monitoring and reporting program.
Table 3-5 presents analytical results for the six wells containing water (beginning in 1987 for West,
MW4 and Gorge wells and 1988 for MW5 and South wells). All but the Gorge well (also known as
the East well) are local to the tailings impoundment. MW1, MW2 and MW3 are dry and have never
been sampled. Established limits for these wells were not available, but, a general provision of the
waste discharge requirements dictates that free cyanide may not exceed 0.2 mg/1 and other monitored
parameters may not exceed 20 percent of background concentrations hi ground water. It is unclear
what background concentrations were established for the monitored parameters.
%
Colosseum's Annual Water Quality Monitoring Report for 1991 states that levels of sodium, sulfate,
TDS and conductivity are in excess of the permitted levels for the West well. Colosseum initially
thought that these high levels probably result from the migration of tailings water pooled along the
western edge of the impoundment near the West well (see Table 3-5). However, the Colosseum Mine
now believes that baseline sulfate levels were artificially lowered by pumping away surface waters
during construction. The Colosseum Mine has collected soil samples up gradient of the West well
that indicate that surface runoff to the well could be a natural cause for the current sulfate levels. The
results and the interpretations are currently being discussed with State Water Quality Control Board
staff.
The monitoring and reporting program also requires the quarterly sampling of eight springs, labeled
as S-11 to S-18 (the location of these springs was not obtained), for the following parameters:
conductivity, pH, temperature, total cyanide, WAD cyanide, TDS, sodium, sulfate, zinc, copper and
iron. No analytical data on the sampling of these springs was obtained.
As noted in section 3.3.2, the leakage detection sumps must be visually inspected each month for the
presence of liquid. If liquid is detected, it must be analyzed for: total cyanide, WAD cyanide, TDS,
sodium and sulfate.
The Regional Water Quality Board also requires Colosseum to provide financial assurances that
monies are available to ensure closure upon abandonment of the facility. The bond was in the form
of a stand-by letter of credit from the Royal Bank of Canada in the amount of $735,000 (Royal Bank
of Canada, 1992a). This bond is separate from the reclamation bond described in section 3.4.1.
3-37
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Site Visit Report: Colosseum Mine
Table 3-5. Results of Required Ground Water at the Colosseum Mine
.--.-.=;,. :'vV-X".:V.;:i
' fturwuiefer:-'.;::;
V'-' "' '.'::-'?:':;l
Conductivity,
mmhos/cm
pH
WAD Cyanide,
ppm
Total Cyanide,
ppm
IDS, ppm
Sulfate, ppm
Sodium, ppm
Copper, ppm
Iron, ppm
Zinc, ppm
Lead, ppm
Minimum and Maximum Concentrations in Ground Water Monitoring WeUs at Colosseum
y"'W«tW«H* "
920 -1,493
6.6 - 7.48
<0.005 - <0.125
<0.005 - <0.25
490-850
50-290
36-63
<0.01 - 0.03
<0.02 - 0.15
<0.02 -8.1
<0.01 - <0.2
MW5**
1,419-1,697
7.15-7.86
< 0.005 - < 0.125
<0.005 - <0.25
760 -1,000
94-250
51-71
<0.0015 - 0.03
<0.02 - 0.1
<0.01 - 0.07
<0.002 - 0.002
MW4***
/
1,022 - 1,300
7.34 -7.79
<0.005 -
<0.125
<0.005 - <0.25
590-662
57 - 140
70-95
<0.001 -0.04
<0.002 - .17
<0.005 - 0.04
<0.001 - 0.003
Gorge
W*D****
1,117-1,365
7.11 - 8.04
< 0.005 -
<0.125
<0.005 -
<0.25
500-690
<1.0-90
42-58
<0.002-
<0.02
<0.02 - .67
.82 - 8.3
<0.002 - .003
South
WeB*****
842 -939
6.92 - 7.47
<0.005 -
< 0.125
<0.005 -
<0.02
370 - 470
18-69
29-43
<0.002-
<0.02
<0.02 - 0.13
<0.03 - 5.3
<0.001 - <0.2
KEY: *Data represent monthly sampling from Sept 1987 to Sept. 1988, quarterly monitoring from Jan.
1989 to Dec. 1990, and monthly sampling from Jan. 1991 to Dec. 1991.
**Date represents monthly sampling from Jan. 1988 to Oct. 1988 and quarterly sampling from
Oct. 1988 to Dec. 1991.
***Data represents monthly sampling from Nov. 1987 to Oct. 1988 and quarterly sampling .from
Jan. 1989 to Dec. 1991.
****Data represents monthly sampling from Nov. 1987 to Oct. 1988 and quarterly sampling
from Jan. 1989 to Dec. 1991.
*****Data represents monthly sampling from Jan. 1988 to Oct. 1988 and quarterly sampling from
Jan. 1989 to Dec. 1991.
Source: Colosseum, Inc., 1992a.
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Sire Visit Report: Colosseum Mine
3.4.4 Air Pollution Control District, San Bernardino County
Colosseum holds fourteen permits issued by the Air Pollution Control District, San Bernardino
County, California, for the operation of various components of the Colosseum Mine (San Bernardino
County Air Pollution Control District, 1991a). These are shown in Table 3-6, along with a listing of
special conditions imposed upon each unit. General conditions the permits include:
Comply with all applicable rules and regulations of the San Bernardino County Air
Pollution Control District, and
Ensure that construction, maintenance and operation of the stationary source is in
compliance with all applicable provisions of Federal, State and District regulations.
3.4.5 Other Permits
The Colosseum Mine also holds permits from the California State Division of Safety of Dams and the
Environmental Health Services Department, San Bernardino County, California.
Colosseum Mine was issued a permit (number 2800) by the Division of Safety of Dams for the
operation of the mine tailings dam. An annual operational report is submitted to the Division
containing a number of statistics (e.g., the current dam crest level, the total tailings deposited in the
impoundment throughout the year, etc) (Colosseum, Inc., 1992b). The requirements of this permit
were not obtained.
The mine is a small quantity generator of hazardous waste and is identified by the mine's EPA
Hazardous Waste Number CAD982459968. The mine has two hazardous waste permits issued by the
Environmental Health Services Department, San Bernardino County, California. Permit No.
8709080011 allows Colosseum to handle hazardous materials. Permit No. 8709080010 allows
Colosseum to generate hazardous waste. The requirements of these permits were not determined
(County of San Bernardino, Environmental Health Services, Undated).
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Site Visit Report: Colosseum Mine
Table 3-6. Air Pollution Control Permits
Permit;
Number
Unit Covered
' "
Special Conditions of the Permit
B001822
Ore Crashing Unit
'Unit must only operate concurrently with the wet
scrubber permit #001830
Ducting to the wet scrubber must be maintained as air
tight.
Dust control water sprays must be functioning at the ore
bin when ore is dumped by haulage trucks.
Mining is limited to 31,000 tons of rock per 24-hour
day.
Operator must maintain a log of mining rates.
B001823
Leach and Carbon
Adsorption
Water sprays must be working during the addition of ore
to the crushed ore stockpile.
Water sprays shall be used in severe weather conditions
(strong winds) when ore in not being added to the
stockpile.
B001824
Leach and Carbon
Adsorption
Equipment must be maintained and operated consistent
with manufacturer's recommendations and/or sound
engineering practices.
B001825
Tailings Thickener
and Treatment Unit
Equipment must be maintained and operated consistent
with manufacturer's recommendations and/or sound
engineering practices.
B001826
Carbon Stripping and
Regeneration Unit
Equipment must be maintained and operated consistent
with manufacturer's recommendations and/or sound
engineering practices.
B001827
Cyanide Destruction
Unit .
Operate concurrently with and vented to the functioning
lime bin baghouse (permit C001832)
Equipment must be maintained and operated consistent
with manufacturer's recommendations and/or sound
engineering practices.
B001828
Plant Air
Compressors
Equipment must be maintained and operated consistent
with manufacturer's recommendations and/or sound
engineering practices.
B001830
Scrubber - Venturi
Operate concurrently with the crushing unit and
appurtenant equipment.
Maintain entire system consistent with manufacturer's
recommendations and good engineering practices.
Maintain log on-site
Conduct emission tests (within 90 days of receipt of thi»
permit) on outlet of scrubber to determine compliance
C001831
Water Sprays (Fine
Ore)
Maintain in good working order consistent with sound
engineering practices to ensure emissions compliance
Operate when fine ore is added to stockpile.
Operate during severe weather (strong winds).
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Site Visit Report: Colosseum Mine
Table 3-6. Air Pollution Control Permits (continued)
Permit
Number
B001832
B001833
B002295
B002588
T003024
Unit Covered
Lime Bin Dust
Collector
Lime Bin Dust
Collector
Portable Lime Slaking
Unit
Cone Crusher
Gasoline Dispensing
Facility (Non-Retail)
Special Conditions of the Permit
Maintain a minimum inventory of bags at SO percent of
the required bags.
Maintain an on-site log of all inspections, repairs, and
maintenance performed.
Maintain a minimum inventory of bags at SO percent of
the required bags.
Maintain an on-site log of all inspections, repairs, and
maintenance performed.
Operate in accordance with recommendations of the
manufacturer and sound engineering principles.
Ensure sufficient liquid in Porta Batch Mixing Tank prior
to connecting of pneumatic devices.
Ensure that the materials processed contain sufficient
natural and natural moisture for compliance.
Provide piping to effect any necessary addition required
to avert water freezing.
Construct to be air tight as practicable to preclude
fugitive emissions and to allow retrofit of control
equipment hi the future.
Post toll free telephone number.
Source: San Bernardino County Air Pollution Control District, 1991a through 1991n.
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Site Visit Report: Colosseum Mine
REFERENCES
Jtttaway, Michael. Undated. Environmental Compliance at the Colosseum Mine.
Bond Gold Colosseum, Inc. Undated. Flow Chart for 1990 Circulation. '
Bond Gold Colosseum, Inc. Undated. Approved Reclamation Plan.
Bond Gold Colosseum, Inc. 1989. Emissions Summary for 1989 and prioritization scores.
Bond Gold Colosseum, Inc. 1990. Emissions Summary for 1990 and Prioritization Scores.
Bond Gold Colosseum, Inc. 1990b. Colosseum Mine Data Sheet. July 12, 1990.
Bureau of Land Management and San Bernardino County. 1985a. Draft Envirpnmental Impact
Report/Environmental Impact Statement for the Proposed AMSELSO Colosseum Project. March
1985.
Bureau of Land Management and San Bernardino County. 1985b. Final Environmental Impact
Report/Environmental Impact Statement for the Proposed AMSELSO Colosseum Project. July
1985.
California Regional Water Quality Control Board, Lahontan Region. 1987a. Board Order No. 6-87-20
Revised Waste Discharge Requirements for Colosseum Gold Mine, San Bernardino County.
California Regional Water Quality Control Board, Lahontan Region. 1987b. Monitoring and
Reporting Program No. 87-20 for Colosseum Gold Mine, San Bernardino County.
Colosseum, Inc. Undated. Summary, of Ivanpah Well Data.
Colosseum, Inc. 1988. Facility Map. March 1988.
Colosseum, Inc. 1989a. General Site Map. January 1989.
Colosseum, Inc. 1989b. Revised Facility Map. February 1989.
>
Colosseum, Inc. 1991. 1991 Yearly Report, Division of Dam Safety.
Colosseum, Inc. 1992a. Annual Water Quality Monitoring Report for 1991 as Required by California
Regional WQCB Order No. 6-87-20. January 12, 1992.
Colosseum, Inc. 1992b. 1991 Yearly Report to the Division of Safety of Dams. 1992.
Colosseum, Inc. 1992c. 1991 Hazardous Waste Report, Identification and Certification. February 14,
1992.
Colosseum, Inc. 1992d. Memorandum to Paul Nordstrom, Colosseum from Lynn Holden, Colosseum
RE: INCO Cyanide Destruction and Electrowinning Information for EPA Case Study. July 30.
1992.
3-42
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Sire Visit Report: Colosseum Mine.
Colosseum, Inc. 1992s. Letter to V. Housman, EPA from P. Nordstrom, Colosseum Inc. RE:
Information request. August 4, 1992.
County of San Bernardino, Environmental Health Services Department. Undated. Hazardous Material
Handler. s
County of San Bernardino, Environmental Health Services Department. Undated. Hazardous Waste
Generator.
Holden, H. L. 1991. Variable Speed Drive SAG Milling at the Colosseum Mine. SME Preprint 91-
82. Presented at the SME Annual Meeting Denver, Colorado - February 25-28, 1991.
McClure, D.L. and Schull, H. W. 1988. Colosseum Gold Mine Clark Mountain Range, San
Bernardino County, California. SME Preprint 88-119. Presented at the SME Annual Meeting
Phoenix, Arizona - January 25-28, 1988.
Royal Bank of Canada. 1992a. Stand-by Letter of Credit: Bond Gold Corporation. Beneficiary:
California Regional Water Quality Control Board - Lahontan Region. January 29, 1992.
Royal Bank of Canada. 1992b. Stand-by Letter of Credit: Bond Gold Corporation. Beneficiary: U.S.
Department of the Interior, Bureau of Land Management or State of California Department of
Conservation, Division of Mines and Geology. January 29, 1992.
San Bernardino County Air Pollution Control District. 1991a. Permit No. B001822 to Operate Ore
Crushing Unit. August 28, 1991.
San Bernardino County Air Pollution Control District. 1991b. Permit No. B001823 to Operate Leach
and Carbon Adsorption. August 8, 1991.
San Bernardino County Air Pollution Control District. 1991c. Permit No. B001824 to Operate Leach
and Carbon Adsorption. August 8, 1991.
San Bernardino County Air Pollution Control District. 1991d. Permit No. BOO 1825 to Operate
Tailings Thickener and Treatment Unit. August 8, 1991.
San Bernardino County Air Pollution Control District. 1991e. Permit No. B001826 to Operate
Carbon Stripping and Regeneration Unit. August 8, 1991.
San Bernardino County Air Pollution Control District. 1991f. Permit No. B001827 to Operate
Cyanide Destruction Unit. August 8, 1991.
San Bernardino County Air Pollution Control District. 1991g. Permit No. B001828 to Operate Plant
Air Compressors. August 8, 1991.
San Bernardino County Air Pollution Control District. 1991h. Permit No. B001830 to Operate
Scrubber - Venturi. August 8, 1991.
San Bernardino County Air Pollution Control District. 1991i. Permit No. B001831 to Operate Water
Sprays (Fine Ore). August 8, 1991.
3^3
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Site Visit Report: Colosseum Mine
San Bernardino County Air Pollution Control District. 1991J. Permit No. B001832 to Operate Lime
Bin Dust Collector. August 8, 1991.
San Bernardino County Air Pollution Control District. 1991k. Permit No. B001833 to Operate Lime
* Bin Dust Collector. Augusts, 1991.
San Bernardino County Air Pollution Control District. 19911. Permit No. B002295 to Operate
Portable Lime Slaking Unit. August 8, 1991.
San Bernardino County Air Pollution Control District. 1991m. Permit No. B002588 to Operate Cone
Crusher. August 8, 1991.
San Bernardino County Air Pollution Control District. 199 In. Permit No. T003024 to Operate Cone
Crusher. September 27, 1991.
Sergent, Hauskins and Beckwith. Undated. Boring Logs of the Tailings Dam'and Disposal Area,
Colosseum Project.
Sharp, James E. 1984. A Gold Mineralized Breccia Pipe Complex in the Clark Mountains, San
Bernardino County, California. Arizona Geological Society Digest. Volume 15, 1984.
Steffen Robertson and Kirsten. Undated. Tailings Impoundment Stability, Colosseum Mine.
U.S. Environmental Protection Agency. Undated. Acknowledgement of Notification of Hazardous
Waste Activity.
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Site Visit Report: Colosseum Mine
APPENDIX 3-A
COMMENTS SUBMITTED BY COLOSSEUM ON DRAFT SITE VISIT REPORT
3-45
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Site Visit Report: Colosseum Mine
[Comments not reproduced for this electronic version. Copies may be
obtained from U.S. EPA, Office of Solid Wastes, Special Waste
Branch.]
3-46
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Site Visit Report: Colosseum Mine
APPENDIX 3-B
EPA RESPONSE TO COMMENTS SUBMITTED BY
COLOSSEUM INC.
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Site Visit Report: Colosseum Mine
EPA Response to Comments Submitted by
Colosseum, Inc. on Draft Site Visit Report
EPA has revised the report to address all of the comments made by Colosseum, Inc., submitted
following their review of the Draft Site Visit Report dated September 1992. In some cases, EPA
made changes to'wording suggested by Colosseum, either for brevity, in order to attribute changes to
Colosseum, or to enhance clarity.
3-48
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Site Visit Report: Nerco Minerals Cripple Creek
MINE SITE VISIT:
NERCO MINERALS
CRIPPLE CREEK OPERATIONS
U.S. Environmental Protection Agency
Office of Solid Waste
401 M Street SW
Washington, DC 20460
-------
Site Visit Report: Nerco Minerals Cripple Creek
4.0 SITE VISIT REPORT: NERCO MINERALS CRIPPLE CREEK
4.1 INTRODUCTION
4.1.1 Background
The Environmental Protection Agency (EPA) is assisting states to improve their mining programs.
As part of this ongoing effort, EPA is gathering data related to waste generation and management
practices by conducting site visits to mine sites. As one of several site visits, EPA visited the
Ironclad/Globe Hill facility near Cripple Creek, Colorado, on April 14, 1992.
Sites to be visited were selected to represent both ah array of mining industry sectors and different
regional geographies. All sites visits have been conducted pursuant to RCRA Sections 3001 and 3007
information collection authorities. When sites are on Federal land, EPA has invited representatives of
the land management agencies (Forest Service/Bureau of Land Management). State agency
representatives and EPA regional personnel have also been invited to participate in each site visit.
For each site, EPA has collected information using a three-step approach: (1) contacting the facility
by telephone to get initial information, (2) contacting State regulatory agencies by telephone to get
further information, and (3) conducting the actual site visit. Information collected prior to the site
visit is then reviewed and confirmed during the site visit.
In preparing this report, EPA collected information from a variety of sources, including Nerco
Minerals Company, the Colorado Mined Land Reclamation Division, and the Colorado Department of
Health. The following individuals participated in the site visit:
Nerco Minerals Company
Jim Muntzert, Mine General Manager, Pikes Peak Mining Company (719) 689-2977
John Woodward, Manager, Environmental Compliance (503) 796-6600
Colorado Mined Land Reclamation Division
Bruce Humphries, Minerals Program Supervisor (303) 866-3S67
Carl B. Mount, Senior Reclamation Specialist (303) 866-3567
U.S. Environmental Protection Agency
Van Housman, Chemical Engineer (703) 308-8419
Rob Walline, Mining National Expert (303) 293-7093
4-1
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Site Visit Report: Nerco Minerals Cripple Creek
Science Applications International Corporation
Jack Mozingo, Environmental Scientist.
Laurie Lamb, Geologist
(703) 734-2513
(303) 292-2074
Participants hi the site visit were provided an opportunity to comment on a draft of this report.
Nerco Minerals Company submitted comments on the draft, which are presented hi Appendix 4-C.
EPA's responses to Nerco Minerals Company's comments are summarized hi Appendix 4-D.
"" > /
4.1.2 General Facility Description
The Ironclad/Globe Hill facility and Nerco's other Cripple Creek operations are located in Teller
County, Colorado, near the historic mining towns of Cripple Creek and Victor (see Figure 4-1).
Mining has occurred hi the area since the mining district was organized during the gold rush of the
early 1890s. The mining district is characterized by abandoned headframes, waste rock dumps, and
hundreds of openings to underground mines. Other than mining, predominant land uses include
grazing and ranching. The colorful mining past, reflected hi the remnants of historic operations, also
makes tourism a mainstay of the local economies. In Cripple Creek, recently authorized gambling
has begun to dominate the economy.
Nerco Minerals owns a number of major operations hi the Cripple Creek area, all within one to two
miles of the towns of Cripple Creek and Victor. Nerco's major current activities occur on two main
permits issued by the Mined Land Reclamation Division: the Globe Hill and Ironclad/Victor permits.
The Globe Hill project (MLRD permit number 77-367) was initiated by Gold Resources Joint Venture
hi 1977 as an open pit mine and the Globe Hill heap leach pad. Newport Minerals became the
permittee hi 1979 (Newport Minerals, Inc. 3/29/79) and operated two additional heap leach pads: the
Forest Queen/2A pad, which was constructed on the surface of waste rock from the pit; and the '76
or Bull Hill project, which was used to leach material taken from old waste rock dumps and is located
about one mile southeast of the Ironclad/Globe Hill site. In 1986, Dayspring Mining Corporation
succeeded Newport as the permittee for the entire Globe Hill project and other projects covered by
Permit 77-367 (MLRD 9/25/86). In 1990, Nerco (actually, Nerco subsidiary Pikes Peak Mining
Company) succeeded Dayspring as operator (MLRD 2/6/91). None of the three permitted heap leach
pads has been actively leached for several years.
The Ironclad/Victor operation (permit 81-134) is immediately adjacent to the Globe Hill permit area
Permitted by Silver State Mining Company hi 1981, this operation originally leached ore from the
Ironclad pit hi concrete vats inside the Victor Mill building. Nerco purchased Silver State and
assumed the permit hi 1984 and undertook a major expansion. In late 1985, the facility entered an
extended period of inactivity. Nerco then attempted to sell the Victor property, along with three
mines hi Nevada, hi 1988 (Nerco 9/88). This "small mines package" was withdrawn from the martci
4-2
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Site Visit Report: Nerco Minerals Cripple Creek
Figure 4-1. Cripple Creek and Victor, Colorado, and Major Nerco Operations
(Source: Map used in numerous permit applications, modified by EPA)
4-3
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Site Visit Report: Nerco Minerals Cripple Creek
in 1989 (Nerco 9/89) as Nerco consolidated control over much of the Cripple Creek mining district.
In 1990, Nerco developed plans to re-activate the facility, again as a vat leaching operation. Shortly
thereafter, Nerco (through Pikes Peak Mining Company) assumed the adjacent Globe Hill permit and
developed plans for a large 1,500,000 square foot heap leach pad covering portions of both permit
areas. This pad, the "Ironclad Pad," is being constructed in three phases during 1991 and 1992, and
portions of the developing heap are being actively leached as construction continues on other portions.
Ore for this heap is mined from the Ironclad and Globe Hill open pits. Ultimately, the heap will
contain a total of about 4,400,000 tons of ore.
Besides the Ironclad/Globe Hill operation, Nerco. owns and/or controls a number of other operations
and facilities in the Cripple Creek area: the Carlton Mill (Pads 1 and 2), the Victory Project (the
Portland pit and Pads 3 and 4), the Gold Star open pit, many mine dumps, and large undeveloped.
areas. Permitted areas are shown hi Figure 4-2 and are listed in Table 4-7. Pads 1,3, and 4 were no
longer being actively leached, although reclamation had not begun at the tune of the site visit;
similarly, the Gold Star and Portland pits were no longer being mined, and reclamation of the
Portland pit had begun. In addition, Nerco is th&NPDES permittee for discharges from the Carlton
tunnel, a tunnel that drains much of the mining district. Nerco also has an active exploration program
and is preparing to develop a major open pit mine and heap leach operation in the area: the Cresson
Mine. This operation will be located northwest of the town of Victor. At the time of the site visit,
Nerco planned to submit the permit application for this mine later hi 1992. During the site visit,
Nerco and MLRD indicated that there was some local opposition to the development.
As in many historic mining districts, land ownership patterns are extremely complex. Nearly all of
the district consists of patented lode claims that over the years entered private ownership through the
general mining laws. Through leases, purchases, and other agreements, Nerco now controls about 95
percent of the district, a total of about 14,000 acres. The Bureau of Land Management retains
something less than one percent of the area in parcels ranging up to 0.25 acres in size.
Nerco Minerals Company is owned by Nerco, Incorporated, which also has extensive coal and oil
holdings; the parent company of Nerco, Incorporated, is Pacificorp. Permits issued by the Colorado
Mined Land Reclamation Division for the various Cripple Creek operations are issued to one of
several companies: Nerco Minerals (Victor Mine permit 81-134), Pikes Peak Mining Company
(Globe Hill permit 77-367), and Cripple Creek and Victor Gold Mining Company (Victory permit 86-
024, Carlton Mill permit 80-244, and the Carlton Tunnel NPDES permit). Much of Nerco's Cripple
Creek property is held by Cripple Creek and Victor Gold Mining Company (CC&V), a joint venture
between Nerco subsidiary Pikes Peak Mining Company (67 percent) and the Golden Cycle Gold
Corporation (33 percent). Mining operations are managed by Pikes Peak Mining Company, which
was known as Texasgulf Minerals and Metals prior to its 1989 purchase from ELF Aquitane. For
ease of reference, this report simply refers to "Nerco" when discussing the owner, operator, and/or
permittee of any of the Cripple Creek operations.
4-4
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Site Visit Report: Nerco Minerals Cripple Creek
'" < "XX T l^''V~ &
_^ . \ ^~^ ^-^^ JV _ .-^^\J . .
Figure 4-2. Location of Mined Land Reclamation Division Permit Areas Controlled by Nerco
(Source: Provided by Nerco during site visit)
4-5
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Site Visit Report: Nerco Minerals Cripple Creek
4.1.3 Environmental Setting
The Cripple Creek area is subalpine, with elevations ranging from 9,000 feet to over 10,000 feet
above sea level. Elevations at the Ironclad/Globe Hill site exceed 10,000 feet and range up to about
10,400 feet. The entire mining district has experienced massive disturbance, with hundreds of mine
shafts and openings and hundreds of miles of underground workings. Mine headframes dot the
landscape, and there are piles of waste rock and tailings scattered throughout the mining district.
Teller County has designated the entire area as an Historical Preservation Zone. As such, areas are
required to retain their "mining .area flavor," and this is reflected in the reclamation plans for Nerco's
sites.
, j
Many of the abandoned mine shafts and openings present a safety hazard. According to Nerco, the
Colorado inactive mines program closes about 70 mine shafts and openings in the district each year.
Nerco indicated during the site visit that tourists or other trespassers sometimes present a problem on
their sites.
4.1.3.1 Climate
The climate is semi-arid, averaging only about 16 inches of precipitation a year. Winters are
relatively dry, and snow cover is typically light. Showers and thunderstorms are common from May
through September, during which 60 to 70 percent of annual precipitation occurs. Available
documentation did not describe wind conditions. The 24-hour storm event with a return interval of
100 years (which mine facilities must contain) would generate about 3.5 inches of precipitation.
Winters are typically very long, and the frost-free period averages only 45 to 90 days. The mean
annual temperature in the towns of Cripple Creek and Victor is about 39°F. In January, the mean
minimum temperature (i.e., the average daily low temperature) is 8°F and the mean maximum is
36°F. In July, the mean minimum is 36°F, the mean maximum 72 °F. Temperatures reach as low as
25 to 30°F below zero.
4.1.3.2 Surface Water
There are no perennial streams on or near the site. Mining operations, with the exception of the
bottoms of waste rock dumps and the Cameron and School Section leach pads, occur on ridges and
hilltops and the highest reaches of ephemeral drainages. The lower reaches of drainages, in the
intervening gulches and valleys, flow only hi response to rainfall and snowmelt and reach perennial
streams (Cripple Creek, Founnile Creek, and Beaver Creek) over a mile downstream. There may
have been springs hi many of the tributary drainages in the past, but the permeable ground surface,
extensive underground workings, and deep drainage (the Carlton Tunnel) have "all but eliminated"
their expression (MLRD 7/1/85).
4-6
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Site Visit Report: Nerco Minerals Cripple Creek
Two gulches that are dry except in response to precipitation events drain the Globe Hill permit area
(number 77-367): Poverty Gulch, which discharges into Cripple Creek in the town of Cripple~Creek;
and Squaw Gulch, which discharges into Cripple Creek about 1.25 miles south of the town. There
was. also a reservoir east of the 1977 waste dump and an emergency catch basin in the bed of Squaw
Gulch, the latter intended to intercept any pregnant solution that escaped the Globe Hill pregnant
pond. (Gold Resources Joint Venture, 1977) According to Nerco, these two facilities have been
removed since present leach pads at Ironclad/Globe Hill dram to the east through collection ditches.
In the Victor Mine permit area (number 81-134), the mine pit, waste rock dumps, and part of the
mine facilities and old tailings disposal area are in the upper reaches of Squaw Gulch. Much of the
remaining Victor Mine facilities, including the old tailings disposal areas and the new Ironclad heap,"
are on the drainage divide between Squaw Gulch (to the west and south) and Grassy Creek (to the
north and east). (Nerco 6/20/84) At least the lower reaches of Grassy Creek"lie outside the Cripple
Creek caldera and thus are not affected by the deep drainage of the Carlton Tunnel. Like other
drainages in the area, however, Grassy Creek is not a perennial stream: hi most years, it is
intermittent hi nature until just above its confluence with Beaver Creek about 2.3 miles down the
valley (MLRD 7/1/85). During the site visit, Grassy Creek was flowing. A spill of cyanide solution
in 1985 (see section 4.4.5.4) entered the Grassy Creek drainage area but did not reach the Creek
itself.
Other permitted areas drain to various dry gulches and ephemeral drainages hi the area. Portions of
the Victory project (pads 3 and 4) and the '76 project drain to Wilson Creek. Nerco indicated that it
had removed over 500,000 tons of waste rock from this drainage for use as ore on heap leach pads.
Portions of this drainage appeared during the site visit to have well-established vegetation, and the
creek was flowing at that tune. A small wetlands area occurs in Arequa Gulch, immediately
downstream of the Carlton Mill. Development of the Cresson deposit is planned in this area, and a
permit under section 404 of the Clean Water Act has been issued by the U.S. Army Corps of
Engineers. Water quality data for Arequa Gulch, upstream and downstream of the Carlton Mill heap
leach pads, are presented in section 4.3.6.1.
4.1.3.3 Ground Water
There is little or no available ground water in the area. The Carlton Tunnel, at an elevation of about
7,000 feet, or 3,000 feet below the surface, has since 1941 drained the hundreds of underground
workings that honeycomb the subsurface. (As described in section 4.4.2, the Carlton Tunnel
discharges to.Fourmile Creek about six miles south of the Cripple Creek area.) Prior to this, the
1907-1917 Roosevelt drainage tunnel drained much of the mining district to a depth of about 2,000
feet.
In at least some ephemeral drainages below Nerco'f hilltop operations, there is shallow alluvial
ground water. Below the Carlton Mill, a rancher obuira water from a well that was described by
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Nerco as 14 feet deep. In addition, there is perched ground water in the Grassy Creek drainage
(MLRD 7/1/85). Information was not available on the quality of these alluvial ground waters, or on
the presence and quality of any alluvial aquifers that may occur hi other drainages.
Because of the lack of surface or ground waters in the area, Nerco obtains water for all its Cripple
Creek operations' from the town of Victor. This is described in section 4.3.5.3.
4.1.3.4 Vegetation
At the time of the original Globe Hill project application in 1977, vegetation on this portion of the
site consisted of grasses, weeds, and forbs. The ground cover was said to be less than 10 percent,
with range condition described as "poor." (Gold Resources Joint Venture, 1977) Similarly,
bunchgrasses as .well as various forbs and shrubs dominated vegetation on the,Victor site. Trees in
relatively undisturbed areas included Ponderosa and lodgepole pine, Douglas fir, blue spruce, and
quaking aspen. (Silver State Mining Corporation 3/25/81, MLRD 7/1/85). Other Nerco sites were
similarly disturbed before modern operations occurred, and vegetation was similar on these sites.
4.1.3.5 Soils
Predominant soils on north- and east-facing slopes are mixed Argic Cryoborolls of the "Larand"
series, which consist of well drained soils on mountain sideslopes. Fine sandy loam extends to about
16 inches, underlain by about 16 inches of gravelly sandy clay loam subsoil, which is hi turn
underlain by gravelly sand that extends to 60 inches or more. Permeability of these soils ranges from
0.6 to 20 niches per hour, pH from 5.6 to 6.5 standard units. (Gold Resources Joint Venture, 1977)
Soils of the "Quander" series are found on south- and west-facing slopes. These soils are deep, well-
drained gravelly sandy and clay loam soils that formed hi colluvium from mixed igneous and volcanic
rocks. (Silver State Mining Corporation 3/25/81)
Nearly all of the permitted areas as well as the surrounding district have been affected to some degree
by past mining activities. As a result, much of the areas's soil has been lost to erosion or otherwise
disturbed. What soils existed on areas affected by current operations have been removed (to depths
ranging from 1-2 niches to 12 or more, depending on how much was available) and stored in grass-
seeded topsoil stockpiles. This soil will be used to support reclamation and re vegetation efforts when
mining operations end.
4.1.3.6 Geology
The geology of the Cripple Creek area is dominated by an alkaline volcanic diatreme that formed
circa 28 million years ago during the Tertiary Period. A diatreme is a volcanic vent that is formed by
gas-charged magma penetrating the surrounding country rock. The country rock is composed of
jointed and faulted Precambrian igneous and metamorphic units. The volcanic complex defines the
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Cripple Creek mining district. The complex is composed of the Cripple Creek Breccia, a highly V
variable unit containing diatremal breccia and a variety of volcaniclastic derived breccias and tuffs.
After the formation of the diatreme, the complex was covered and intruded by fine grain igneous
rocks (phonolite flows and hypabyssal dikes). (Thompson 1992, Pontius and Butts 1991)
The larger volcanic complex is composed of three coalesced diatremes. These diatremes have been
roughly identified as the North, South, and East Subbasins (Thompson 1992). The South and East
Subbasins are characterized as having both vein and disseminated gold. These areas were mined since
the early 1900s and include such notable units as the Cresson deposit. Within this deposit, 60,000
ounces of native gold was recovered from an open cavity (vug) 23 feet by 13 feet by 40 feet high.
The Globe Hill and Victor Mines are located in the North Subbasin. Within the Globe Hill and
Victor Mines, gold occurs hi hydrothermal breccia deposits characterized by disseminated gold, with
few veins. However, field evidence suggests that deep level vein systems are-present.
The mineral-bearing hydrothermal fluid appears to have been strongly oxidizing as indicated by the
gangue mineralogy. Iron and manganese oxides, sulfates (celestite SrSO4, barite BaSO4, and
anhydrite CaSO4) as well as carbonate (CaCO3) are abundant in the ore body. Fine grain pyrite
(FejS) also occurs. It is important to note that the alkaline nature of the diatreme and the presence of
carbonate minerals has resulted in relatively low potential for acid generation in the Cripple Creek
area.
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4.2 FACILITY OPERATIONS
As described in chapter 1 and throughout this report, Nerco's Cripple Creek operations include a
number of facilities. The Ironclad/Victor mine is covered by a single Mined Land Reclamation
Division (MLRD) permit (number 81-134), and the adjacent and contiguous Globe Hill operation by
another (number 77-367). The two permits previously covered two entirely separate facilities
operated by different companies. Nerco has consolidated the operations under these permits into the
"Ironclad/Globe Hill" operation, but the areas continue to be covered by separate MLRD permits.
Currently, Nerco's new "Ironclad" heap leach pad (see below and section 4.3.5) covers parts of both
permit areas.
This chapter describes Nerco's current mining (section 4.2.1), heap leaching (section 4.2.2), and gold
recovery (section 4.2.3) operations on the Ironclad/Globe Hill site. Previous operations that took
place on these permit areas, and more details on the facilities (as opposed to operations), are
described in chapter 4.3. Chapter 4.3 also describes both operations and facilities at several of
Nerco's other Cripple Creek operations. Except as specifically noted, all information in this chapter
was obtained during the site visit. Figure 3-3 shows the location of the various facilities on the
Ironclad/Globe Hill site.
4.2.1 Mining Operations
The Ironclad/Globe Hill facility mines ore from two open pits, the Ironclad and Globe Hill pits. The
Globe Hill pit (MLRD permit 77-367) is on a southwest slope near the top of Globe Hill. The pit has
reached a depth of 80 feet, measured from the uphill highwall to the pit floor; the site visit team
estimated the depth on the downhill side at about SO feet. Plans are for the pit to reach a maximum
depth of about 200 feet. Ore from the Globe Hill pit has been leached in heaps since the original
permit was issued in 1977, first on two heap leach pads (the Forest Queen/2A and Globe Hill
padssee section 4.3.3) and now on the Ironclad pad (see sections 4.2.2 and 4.3.5.1).
The Ironclad pit (permit 81-134) is adjacent to the Globe Hill pit, a distance of less than 0.5 miles.
The current pit encompasses part of a previously mined pit that was active around 1904 and the 1930s
(Silver State Mining Company 3/25/81). Ironclad also was mined as a glory hole hi the 1940s, when
manganese and possibly other ores were mined. Since being mined for disseminated gold ore
beginning in 1981, the pit has reached a depth of about 200 feet, measured from the uphill highwall
to the floor; the site visit team estimated the depth on the downhill side at 50 to 75 feet. Openings to
numerous underground workings that have been intersected by the pit were observed during the site
visit. The uphill wall of the pit has a slope of about 60 degrees; according to Nerco, this slope is
extreme but has remained stable. During the site visit, it appeared that only minor sloughing had
occurred. Formerly, ore from the Ironclad pit was leached in vats, as described in section 4.3.4; ore
is now leached on the Ironclad pad.
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Cr..k * Victor Cold Mininj
IRONCLAD/GLOBE HILL MINE
Figure 4-3. Location of Ironclad/Globe Hill Faculties (MLRD Penults 77-367 and 81-134)
(Source: Provided by Nerco during site visit, with additional labels added by EPA)
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Rock in the pits is drilled on 15-foot centers, and each hole is assayed to direct mining operations.
Flags of different colors are used to identify material as waste rock or ore prior to removal. The
cutoff grade between waste rock and ore is 0.015 Troy ounces of gold per ton of rock (i.e., material
with greater than 0.015 Troy ounces of gold per ton of rock is considered ore and material with less
is waste rock). Ammonium nitrate/fuel oil (ANFO) is used as the blasting agent, with an unspecified
emulsion used when holes are wet. The pits are mined on 20-foot benches. A total of about 45,000
tons of material per day are mined, with approximately half coming from each pit. About 8,000 to
15,000 tons of mined material are ore and 30,000 to 37,000 tons are waste rock. The stripping ratio,
according to Nerco, typically ranges from 2.7:1 to 3.0:1 (i.e., 2.7 to 3.0 tons of waste rock per ton
of ore).
Caterpillar 992 loaders with capacities of 12.5 cubic yards load blasted waste rock or ore into 85-ton
Caterpillar 777 haul trucks. The trucks haul waste rock to the waste rock dump, which extends along
the hillsides immediately adjacent to and between the pits. Much of the haulageway from the pits to
the edge of the pile traverses the top of the waste rock pile. Rock is dumped over the edge at an
angle of repose of about 1.35 horizontal to 1 vertical (about 37 degrees). At the base of the pile,
Nerco maintains a berm to contain stray rocks and boulders. Periodically, the addition of waste rock
advances the toe of the pile farther downslope into the ephemeral drainage. Before this occurs, Nerco
is required to strip and store topsoil before waste rock is allowed to impinge on those areas. At the
time of the site visit, the dump contained a total of about 5,000,000 tons of waste rock. In addition,
about 121,000 tons of topsoil were in a stockpile near the dump (see Figure 4-3).
Ore is transported in the haul trucks out of the pits to one of two unlined stockpiles. One stockpile,
which contains about 300,000 tons of ore, is located between the Globe Hill pit and the edge of the
waste rock dump; ore from the two pits is kept separate in this pile. The second stockpile, of
undetermined size, is near the jaw crusher. This area is located on the hilltop immediately above the
pits, a distance of less than one-half mile. In the crusher stockpile, ore with relatively high clay or
fines content is kept separate from other ore (the clay cutoff was not determined). Loaders blend the
fine and coarse ore (to maintain a consistent feed to the crusher) and move the ore the short distance
(less than 100 feet) from the stockpile to the jaw crusher.
The crusher and conveyor systems are operated by a contractor, Nordic Industries.- Ore is crushed (at
an unspecified rate) in a primary jaw crusher to a nominal diameter of less than three inches and
passed over a one-inch screen. Fine (less than one inch) and coarse materials are placed on separate.
parallel conveyors (the proportions greater than and less than one inch were not determined). The
fine ore is agglomerated with cement at a rate of seven pounds of cement per ton of ore. This
agglomerated ore is then combined with the coarse ore on a third conveyor. On the consolidated
conveyor, lime is added to raise pH (five to seven pounds of lime per ton of ore). Cement and lime
are added from storage silos that straddle the respective conveyors; the sizes of the silos were not
determined. In addition, a sodium cyanide solution (about 0.25 pounds of sodium cyanide per ton trf
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Site Visit Report: Nerco Minerals Cripple Creek
solution) is added to ore on the conveyor to raise the moisture content to about six percent (compared
to the mined ore moisture of about four percent) and initiate leaching. The means by which cyanide
solution is conveyed from the barren solution tanks in the mill building to the conveyor was not
determined, but it appeared that the solution was distributed along the conveyer in otherwise
unprotected rubber hoses about 0.5 to one inch in diameter. The conveyor transports the ore from
the crushing area to the appropriate cell on the Ironclad leach pad, where ore is stacked on the heap.
During the site visit, it was noted that ore fallen from the conveyors hi the crusher area (both before
and after cyanide addition) had reached a depth of one to two feet under the conveyors. Workers
were observed shoveling some of this stray ore back onto the conveyor. Most of the stray ore
appeared to be relatively fine material.
4.2.2 Leaching Operations
As described hi more detail hi section 4.3.5, the Ironclad heap leach pad system is being constructed
hi three phases, with the first phase begun hi 1991 and the final phase completed hi 1992 (see Figure
4-3). When complete, the new pad will cover about 1,500,000 square feet and will contain about
4,400,000 tons of ore (see Figure 4-4 for the planned finaT configuration of the Ironclad heap). As
construction proceeds, sections of the various phases of construction are being placed hi operation and
actively leached. By early 1992, portions of the Phases I and n pads had been completed and
leaching had begun (see section 4.3.5); these will become part of the single large Ironclad heap when
Phase m is complete hi 1992. The amount of ore that has been placed on these sections to date was
not determined.
Ore is stacked hi 20- to 30-foot lifts (based on MLRD inspection notes rather than other descriptions)
and will reach a final height of over 100 feet (based on contour maps, not oh narrative descriptions in
available documentation). Maximum side slopes, and whether these are specified by MLRD, were
not described.
Barren solution is made up hi three 60,000 gallon tanks hi the mill building. According to Nerco.
barren solution has a cyanide concentration of 80 to 100 parts per million (ppm) and a pH between
11.5 and 12. Milsperse 802 is added to barren solution as an antiscalant (the rate .and amount added
were not known). Solution is pumped to the pads and applied via drip irrigation pipes to 80,000
square foot active leaching cells at a rate of about 400 gallons per minute (gpm), or 0.005 gallons per
square foot per minute. Leaching raises the moisture content of the ore from about six percent to
about 15 to 18 percent. The length of tune each subcell is leached was not determined. Leaching
occurs year-round, unlike many previous heap leach operations hi the Cripple Creek area. According
to Nerco, there may be occasional freezing hi solution lines when temperatures are very low. Nerco
indicated that on one occasion, an overnight power outage resulted in about 70
percent of the solution lines freezing. All had thawed and were operational by noon the following
day, with no apparent ill effects.
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Figure 4-4. Planned Final Configuration of Ironclad Heap
(Source: Nerco 5/10/91, with additional labels added by EPA)
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The heap leach pads are double-lined (80-mil HDPE primary upper liner over 60-mil HDPE
secondary lower liner, with a leak detection system between the liners-see section 3.5 for detailed
descriptions of pad and pond construction). Pregnant solution is collected in eight-inch diameter
slotted HDPE pipes placed beneath the ore on the upper liner; solution drams from the pipes to
collection ditches that extend along the downslope sides of the pads (on the north and east of the
Phase I pad, on the west of the Phase II pad). As described in section 4.3.5, ditch liners are simply
extensions of pad liners. Solution is conveyed to a stilling basin, which slows the flow before
solution is directed to the pregnant solution pond or, if necessary, an emergency overflow pond. All
ponds are double-lined, with two 60-mil HDPE liners and a geotextile leak detection system between;
pond construction is described in detail in section 4.3.5. The total capacity of the three solution
ponds is 10,000,000 gallons, sufficient to hold working solution and run-off from the 100-year/24-
hour storm, Pregnant solution, as pumped to the Victor Mill building, has a pH of about 11.
*
4.2.3 Gold Recovery Operations
Gold recovery operations occur in the Victor Mill building, which also contains the vats formerly
used for leaching (see section 4.3.4). Pregnant solution is pumped from the Ironclad solution ponds
to the mill building, where gold is recovered from the pregnant solution in two carbon-in-column
circuits. Each circuit consists of four portable columns (each "column" is an enclosed tank or vessel)
that operate in series. Each column in a four-vessel series contains 1.0 to 1.25 tons of activated
carbon. The size of the columns was not determined, but they appeared to be about 15,000 gallons.
Pregnant solution is pumped at a rate of 250 to 400 gallons per minute into the bottom of the first
column, up through the carbon, and out through pipes at the top. Similarly, it is pumped to and
through the other three columns in series. When solution exits the top of the fourth column, it is
directed to one of three 60,000-gallon barren solution makeup tanks, which are also located in the
mill building. Nerco periodically assays the tails solution from each column. When the gold
concentration rises to some unspecified level, which indicates that the carbon is no longer adequately
adsorbing gold, a column with fresh carbon is substituted hi the train.
Loaded carbon is removed from the columns for further processing (as described below) and replaced
with fresh carbon. According to Nerco, it typically takes three to four days for carbon in a column to
become fully loaded, but this can take up to a month. Nerco has a total of 32 portable columns; at
the time of the site visit, eight were in use at the Ironclad/Globe Hill site in two parallel circuits and
four at the Carlton Mill Pad 2 [see section 4.3.6.1]. The other twenty are held hi reserve as
replacements for columns with loaded carbon and presumably for Cresson operations when they
begin. (When columns at Carlton Mill Pad 2 are loaded with gold, a fresh column is substituted in
the train and the column with loaded carbon is transported to the Victor Mill hi a specially designed
truck. Prior to January 1992, columns were transported to the Carlton Mill for gold recovery and
carbon regeneration).
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Gold is desorbed (stripped) from the loaded carbon with a caustic wash (one percent sodium
hydroxide, one percent sodium cyanide) in one of two enclosed tanks (the size was not determined,
but they appeared to be about 50,000 gallons each). The strip circuit is operated at 240°F, at a
pressure of SO pounds per square inch.. Stripped carbon is then acid-washed with hydrochloric acid,
regenerated in a propane-fired Allis-Chalmers horizontal kiln, and quenched with water before storage
and reuse. According to Nerco, spent acid and quench water are returned to "process water ponds"
(presumably the pregnant solution pond)the amounts of fresh acid and reactivated carbon stored on-
site were not determined. Carbon fines are shipped off-site for gold recovery: the point in the
process at which carbon is screened to remove fines was not determined, but Nerco indicated that
they generate about one barrel of fines per year. The facility uses about SO tons of carbon per year.
Spent carbon is shipped off-site with the carbon fines.
The gold-laden caustic solution goes to an electrowinning cell (the number and" sizes of cells were not
determined). A stainless steel woven wire cathode (steel "wool") acts as the cathode onto which gold
is plated (along with small amounts of silver). The steel wool is then removed, washed with high-
pressure water, and filtered. The filter cake is then placed in a propane-fired tilt furnace, where gold
is melted off the steel wool to produce dor6 (a conventional flux also is used in the furnace). A wet
scrubber is used to control furnace emissions. According to Nerco, significant (but unspecified)
amounts of gold are recovered from scrubber sludges, which are sent off-site for gold recovery about
once a year; the volume of sludges shipped was not known. (Since the Ironclad leaching operation
only began operation in early 1992, it is not clear if the reported volumes and frequency of removal
of carbon fines and sludge were estimated for the future or are based on Carlton Mill operations for
the previous year.) Overall, Nerco reported that from 70 to 85 percent of soluble gold in mined ore
is recovered. '
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4.3 MATERIALS AND WASTE MANAGEMENT
Chapter 4.2 described operations on the Victor Mine and Globe Hill permit areas, the consolidated
"Ironclad/Globe Hill" site. 'This site was the primary focus of the site visit. Sections 4.3.1 through
4.3.5 of this chapter describe the facilities on these permit areas and the wastes and materials that are
managed there by Nerco. Figure 4-3 showed the locations of facilities described in these sections.
Active facilities are described in sections 4.3.1, 4.3.2, and 4.3.5. An understanding of previous
operations on the site is necessary hi order to understand current operations and also to allow the
complexity of the site to be conveyed; in addition, wastes generated by previous operations remain on
the site. For these reasons, previous operations and facilities on these permit areas are described in
this chapter (in sections 4.3.3 and 4.3.4). Finally, section 4.3.6 describes a number of Nerco's other
Cripple Creek operations.
' %
4.3.1 Mine Pits
The Ironclad/Globe Hill operation currently mines ore from two open pits, the Globe Hill and
Ironclad pits. As described in Chapter 4.2, the Globe Hill pit has reached a depth of 80 feet and
plans are to continue to a final depth of about 200 feet. The Ironclad pit has reached 200 feet and
plans are to continue to a final depth of about 400 feet (the areal extent of the two pits was not
determined). Ore from the two pits is commingled at the crusher plant. As noted in section 4.2.1,
the Ironclad pit has intercepted a number of underground workings, which are clearly visible in the
high walls; none were observed in the Globe Hill pit, but they may be encountered as the depth of the
pit increases. At the Ironclad pit, tailings from historical mining operations were being encountered
by mining operations and were observed during the site visit.
Ground water has not been and is not expected to be encountered in either pit, since the ground-water
regime to a depth of about 3,000 feet (to an elevation of about 7,000 feet above sea level) is
dominated by drainage to the Carlton Tunnel. There is little or no upslope area from which run-off
drams into the pits, and the only water that accumulates hi the pit is from direct precipitation. Any
such accumulation evaporates and has not required pumping or other removal to date.
Reclamation requirements for the Globe Hill pit include leaving a safety or warning drop bench no
more than 15 feet below the top of the pits (Silver State Mining Corporation 3/25/81, MLRD 9/8/81).
In the Ironclad pit, a 20-foot-wide drop bench will be left about 20 feet below the pit's rim (Nerco
6/19/84). Final pit walls in the Ironclad pit may be benched at 30-foot intervals, with a final slope of
45 to 55 degrees (this was not described for the Globe Hill pit). There will be a ramp into each pit to
increase pit wall stability and to allow exit by trespassers and wildlife. The ramps will be blocked by
berms or boulders to discourage access. The pits will be fenced and appropriate warning signs
posted. Overall, the pits are to be left rough-graded 'without conical peaks or trench-like
excavations," but will not be revegetated, except for the benches and pit floors. This will allow the
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pits to meet Teller County zoning requirements that the area retain its "mining area flavor." (Silver
State Mining Corporation 3/25/81, MLRD 9/8/81, Nerco 6/19/84)
(.
Haul roads from the pits to the waste dump (which are constructed on and across the dump) and to
the stockpile in the crusher area will be reclaimed by smooth-grading to slopes between three and five
horizontal to one vertical (3H:1V to 5H:1V), then mulching and revegetating with grasses and trees
(Silver State 3/25/81, MLRD 9/8/81).
4.3.2 Waste Rock Dump
Waste rock from the pits is taken by truck directly to the mine dump, which is on the hillside on the
east and north slopes of Poverty Gulch and Squaw Gulch immediately adjacent to the pits. As
described in Chapter 4.2, a total of about 45,000 tons of material was being mined per day at the
time of the site visit, of which 30,000 to 37,000 tons were waste rock. About 5,000,000 tons of
waste rock had been disposed in the dump at the time of the site visit (since 1981, when the Victor
Mine permit was issued). The total area covered by the waste rock dump was not determined. At
least a portion of the dump on the Ironclad/Victor permit area is located in an area covered by mine
dumps that predate the modern operations. The waste rock dump used on the Globe Hill before
operations were consolidated is apparently located immediately to the north of the Globe Hill pit; at
least one area of this dump was used to dispose of triple-rinsed and crushed barrels in which cyanide
was received (MLRD 9/28/84). The amount of waste rock in the Globe Hill dump was not
determined.
There is little or no upslope area to contribute run-on, so run-off comes only from direct precipitation
on the surface of the dump itself (the top of which is fairly extensive and serves as the haulageway
from the pits). References hi permit correspondence seemed to refer to one or more sedimentation
ponds at the base of the dumps (MLRD 3/21-22/85, Nerco 1/87). According to Nerco, a
sedimentation pond remains hi place at the base of the dumps. No information was obtained on
whether run-off or other storm water discharges have ever been monitored, either at the base of the
piles or in the ephemeral drainage of Poverty Gulch. As described in section 4.3.3 and 4.3.5 below,
Nerco plans to "detoxify" spent ore on two old heap leach pads (the Globe Hill and Forest Queen/2A
pads) and place it on the waste rock dump. It was not determined if the spent ore Jias a higher
proportion of fines than the waste rock and thus could contribute additional loadings to run-off.
To date, only oxide ores have been encountered and acid generation potential of waste rock was
described by Nerco as very low; no other information on acid generation or neutralization potential
was obtained. As the Ironclad pit increases in depth, Nerco expects an increase in the sulfide content
of ores and waste rock. Actions to be taken by Nerco or MLRD when this occurs had not been
determined at the time of the site visit.
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Waste rock is end-dumped on the pile at the angle of repose, about 1.35H:1V (about 37 degrees). A
geotechnical engineering study by Nerco's consultant found this slope was stable under normal
conditions, and that only minor sloughing would occur in the event of "unlikely" earthquakes (Dames
& Moore 1984). The dump appears to be about 250 feet high. In 1984, gradational analyses of
uncrushed run-of-mine material indicative of Ironclad pit waste rock showed over 60 percent less than
one inch in diameter, with 35 to 45 percent less than one-quarter inch (Nerco 6/19/84).
At the foot of the dump, Nerco is required by MLRD to maintain a berm to intercept errant boulders
that are dumped over the edge. As the dump grows, the base of the dump will continue to be
extended outward. Nerco is required to remove topsoil from areas to be affected by the dump.
Topsoil is stored, and seeded with grasses, in one or more stockpiles at the base. One stockpile,
immediately west of the Globe Hill pit, contains 121,000 tons of topsoil. The topsoil will be used
during reclamation.
Original reclamation plans were for the waste rock dumps to be left rough-graded without conical
peaks or trench-like excavations hi order to retain the "mining area flavor." It was not clear whether
the surface would be covered with topsoil and revegetated. (MLRD 5/22/86 and 9/8/81) However,
reclamation plans for the Ironclad dump call for the upper surfaces of the dump to be graded and
sloped away from the edge in order to prevent erosion; to minimize infiltration, Nerco may use
downcomers or other conveyances to remove precipitation. At the Ironclad waste dumps, stockpiled
topsoil will be used to aid hi revegetation (Nerco 6/19/84), although details on the use of test plots
and final planning were not available. Reclamation requirements for the Globe Hill dump include
rough-grading as well. The upper surface of this portion of the dump is to have a two to three
percent "dome-like" surface to minimize ponding and infiltration. The maximum outer slope is to be
1.5H:1V. Revegetation is apparently not required on the top or slopes. (MLRD 5/22/86)
In 1990, Nerco advised MLRD of its intent to provide two truck loads of waste rock hi a pilot test of
its use as an aggregate for asphalt or other uses. Evaluation and testing were to occur hi Colorado
Springs. (Nerco 9/11/90) The results of any such testing, if it occurred, were not determined.
4.3.3 Heap Leach Pads and Ponds, Permit 77-367 (Globe Hill Projects)
As noted elsewhere, the Ironclad/Victor Mine and Globe Hill projects are in reality a single project,
although they currently are permitted separately. The separate permits are an artifact of their
histories prior to Nerco's consolidation of the operation. The heap leach pads and ponds described hi
this section are not currently active; they are described hi order to indicate the complexity of the site,
because they remain on the site, and because they will be affected by current Ironclad/Globe Hill
operations. Because the heaps are no longer being leached, the spent ore on the heaps are wastes.
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Site Visit Report: Nerco Minerals Cripple Creek
4.3.3.1 Globe Hill Pad and Ponds
One of the first cyanide heap leach projects in Colorado and the west, this pad was originally
permitted, hi 1977, at about four acres, measuring 350 by 500 feet (Gold Resources Joint Venture
1977). Amendment 1 to the permit added another four acres to the pad (Gold Resources Joint
Venture 1978). This brought the total dimensions to roughly 800 by 400 feet (the pad is not
rectangular), about eight acres overall. Other than a Nerco report that the liner consisted of 18 inches
of old tailings from an area mill, information on pad site preparation and construction was not
obtained (Nerco 2/12/86).
The original pregnant pond for this pad was initially 120 by 100 feet, about 0.28 acres (Gold
Resources Joint Venture 1977). Another 1.44 acres was added in 1978, making the pregnant pond's
dimensions 375 x 200 feet, an area of 1.72 acres (Gold Resources Joint Venture 1978). Information
on the pond's capacity was not obtained, nor were descriptions of the liner system (if any) and pond
construction. No information was obtained on the barren pond, if there was one.
Ore came from the Globe Hill pit and apparently was not crushed after blasting (Gold Resources Joint
Venture 1978). In addition, waste rock from various underground mine dumps in the area may have
been used as ore. Information on the means by which barren solution was prepared and stored and
by which pregnant solution was conveyed to the pond and processing facilities was not presented in
the permit application or other available reports and correspondence. Similarly, information on the
processing facilities themselves was not obtained.
When active leaching ended, reclamation requirements were to rinse the heap with fresh water,
followed by an oxidant if cyanide was still detectable. The surface of the heap was to be rough-
graded without conical peaks or trench-like excavations, but not revegetated. The pregnant pond was
to be backfilled and revegetated. (Gold Resources Joint Venture 1978; MLRD 5/22/86) The period
of time in which the Globe Hill heap actually received ore and was actively leached, and when active
leaching ended, could not be determined from available documentation. Nerco reported in 1986 that
the heap's slopes ranged from 1.6 to 1.8 horizontal to 1 vertical (Nerco 2/12/86). The operation's
"stripping plant" (not otherwise described) was dismantled in 1984 hi preparation for the construction
of a vat leaching operation similar to Nerco's adjacent operation (described in section 4.3.4) (MLRD
7/1/85); the vat leaching plan was never implemented. It was not determined if the "stripping plant"
and other gold recovery operations were replaced or if other facilities (e.g., Nerco's adjacent plant)
were used thereafter.
A number of samples of Globe Hill pond liquids were taken in 1985 and later years. Although
available documentation is not explicit, it is believed the liquids hi the pond represented run-off and
precipitation-induced seepage, not active leaching solutions. Sampling results are presented in Table
4-1.
4-20
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-1. Concentrations of Selected Parameters in Globe Hill Heap Pond
(milligrams per liter, unless otherwise indicated)
Parameter
pH (s.u.)
TDS
Total CN
FreeCN
Radium 226
(pCi/L)
Nitrate
Arsenic
Copper
Lead
Silver
Sulfate
Zinc
:'" "". -.":.' '' ?.' - . " Date'' : ' '
4/9/85* ',
NR
NR
0.044
NR
NR
'NR
0.005
0.07
NR
0.001
575
NR
7/19/85*
NR
NR
NR
NR
NR
NR
0.005
0.44
NR
0.020
2,350
NR
6/86*
9.53
NR
0.0025
NR
NR
NR
NR
0.03
NR
0.001
NR
0.011
1/20/89*
4.14*
6,840
0.17
0.04
NR
*
190
< 0.001
1.72
0.12
0.01
3,440
5.57
9/15/89*
4.85'
4,180
0.081
< 0.05
2.1
(+/- 1.6)
113
< 0.002
0.57
0.22
< 0.01
2,480
3.02
NOTES:
NR Not reported
Nerco (3/30/89) speculated that the low pH was attributable to prior efforts to meet reclamation
requirements. (Information on these efforts was not available.)
Sources:
a Newport Minerals 6/24/85
b Newport Minerals 9/24/85
c Newport Minerals 7/18/86
d Table G-l hi Nerco 9/89 (1989 Annual Report to MLRD). January samples taken under 14 inches of ice.
In 1984, the Globe Hill heap and pond were conveyed from Newport Minerals' permit 77-367 to
Nerco's Victor Mine permit 81-134. At that tune, plans were to cover at least part of the heap with a
20-mil PVC liner and tailings from the Victor vat leaching operation; Nerco requested MLRD to
specify decommissioning requirements for the pad before this occurred. (Nerco 6/19/84, 4/2S/8S)
"Environmental responsibility" for the pond (and possibly the pad as well) apparently was to remain
with the Globe Hill operator until Nerco actually used the area for tailings disposal (Nerco 3/30/89).
Whether MLRD provided decommissioning specifications was not determined, and apparently tailings
were never placed on the Globe Hill heap. In 1991, Nerco (actually, Pikes Peak Mining Company)
took over this permit as well, and now has full responsibility for all facets of the Globe Hill permit.
4-21
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Sire Visit Report: Nerco Minerals Cripple Creek
In 1991, Nerco developed plans to construct the Ironclad heap leach pad, covering portions of the
Victor Mine and Globe Hill permit areas (i.e., both permits 81-134 and 77-367). Phase ni of this
project, planned to be completed in 1992, is the construction of a double-lined leach pad where the
Globe Hill heap is located (see section 4.3.5.1). Nerco indicated in the application that the Globe
Hill pad would be "detoxified" before being graded for use as a base for the new pad. (Nerco
5/10/91 and MLRD 10/10/91) During the site visit, Nerco indicated that the heap would be rinsed
with water and, if necessary, an oxidant, until cyanide levels were below 0.2 ppm (whether free,
total, or weak-acid-dissociable cyanide was not specified). Following this, spent ore from the heap
would be placed on the waste rock dump. It was not determined if this detoxification had begun or
had been completed (or even if it would be necessary, since free and total cyanide levels were well
below 0.2 ppm in 1989, as shown in Table 4-1).
4.3.3.2 Forest Queen/2A Heap Leach Pad(s) and Pond(s)
Sometime prior to September 1981, Newport Minerals constructed two additional heap leach pads
within the Globe Hill permit area, the Forest Queen and 2A pads, and began leaching the Forest
Queen heap. The pads were located on the surface of Globe Hill waste rock dump.
The only descriptions of pad site preparation that were obtained were in MLRD correspondence to
and from another mining company (there were none in the permit application or related
documentation). This correspondence noted that the pads did not have synthetic liners or leak
detection systems, but were constructed on 18 to 24 inches of compacted tailings (Reilly 4/6/86;
MLRD 5/22/86). The pond(s) apparently were lined, sincedn 1986 MLRD issued Newport a Notice
of Violation for degradation of the Forest Queen/2A pond liners (MLRD 7/1/86). Other information
on the ponds' liner system and pond construction was not obtained. Similarly, no information was
available on pond capacity.
Ore for the Forest Queen/2A pad(s) came from the Globe Hill pit and/or from waste rock dumps
from various underground mines that had operated in the area. As with the Globe Hill heap leach
pad, the permit application and other available documents do not describe the means by which barren
solution was prepared and stored and by which pregnant solution was conveyed to the pond and
processing facilities. Similarly, information on gold recovery operations was not available.
Also similar to the Globe Hill pad, the period of time during which the Forest Queen/2A heap
received ore and was actively leached, and when active leaching ended, could not be determined from
available documentation (except, as noted above, that the "stripping plant" was dismantled in 1984)
It is known that in later years, the Forest Queen and 2A heaps had become a single heap, known
variously as the Forest Queen, 2A, or Forest Queen/2A heap.
4-22
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Site Visit Report: Nerco Minerals Cripple Creek
Although available documentation is not explicit, it is believed the ponds contained only run-off and
precipitation-induced seepage, not active leaching solutions. Results of two sampling events, in 1985
and 1986, are presented hi Table 4-2; later data were not obtained.
Table 4-2. Concentrations of Selected Parameters in Forest Queen/2A Heap Pond
(milligrams per liter, unless otherwise indicated)
Parameter
pH (s.u.)
TDS
Total CN
Free CN
Radium 226
(pCi/L)
Nitrate
Arsenic
Copper
Lead
Mercury
Silver
Sulfate
Zinc
Date
7/19/85*
NR
NR
NR
NR
NR
NR
0.007
0.03
NR
0.0013
0.011
3,850
NR
6/86"
10.518
NR
0.0025
NR
NR
0.06
NR
0.051
NR
0.005
0.01
- (oz/ton)
210
0.008
NR Not reported
SOURCES:
a Newport Minerals 9/24/85
b Newport Minerals 7/18/86
Reclamation requirements for the Forest Queen/2A heap(s) included rough-grading to exclude conical
peaks or trench-like excavations, but not revegetation since the area was to retain its "mining area
flavor." Pond solution was to be circulated and evaporated to reduce volumes. In addition, the hear*
were to be rinsed with fresh water, followed by an oxidant if cyanide remained. At cessation of
operations, ponds were to be sampled for at least a year; when heap effluent (from run-off and
infiltration of precipitation) became "similar in nature to the fluids naturally occurring in [Crippk
Creek or Wilson Creek]...downstream," the operator could remove the ponds and fences, then grade
and revegetate the pond area. (MLRD 5/22/86; Geddes et al. 11/25/81) In 1985, the ponds
4-23
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Site Visit Report: Nerco Minerals Cripple Creek
associated with the Forest Queen/2A heap were removed from the Newport permit (77-367) and were
apparently conveyed to Nerco Minerals, the operator of the adjacent Victor Mine (permit 81-134)
(MLRD 7/1/85).
Dayspring Mining Corporation, which succeeded to Permit 77-367 in 1986, indicated in 1988 that
neutralization of the "Forest Queen pads" had been completed (Dayspring Mining Corporation
3/17/88). How this was accomplished was not described. As described hi detail hi chapter 4.2 above
and section 4.3.5 below, Nerco (actually, Pikes Peak Mining Company, which succeeded Dayspring
as the permittee in 1990) was constructing a large.heap leach pad that will cover portions of Victor
Mine and Globe Hill property (i.e., both permits 81-134 and 77-367). Phase n of this project,
partially completed by early 1992, is the construction of a double-lined leach pad that covers the area
where the Forest Queen/2A heap is currently located. In the permit amendment, Nerco indicated that
the Globe Hill pad would be "detoxified" before being graded for use as a base for the new pad.
(Nerco 5/10/91, MLRD 10/10/91)
During the site visit, Nerco indicated that the heap would be rinsed with water, and possibly an
oxidant, until cyanide levels were below 0.2 ppm; when this is accomplished, the "detoxified" spent
ore will be placed on the waste rock dump. It was not determined if this detoxification had begun or
had been completed (or whether it would be necessary, since Table 4-2 suggests that cyanide levels
may be below that level). Leaching of at least one subcell of the Phase n heap, a subcell not located
on the Forest Queen portion of the new pad, had begun by early 1992 (see sections 4.2.2 and
4.3.5.1).
4.3.4 Victor Tailings Piles and Previous Vat Leach Operation (Permit 81-134)
v
From the time of initial Victor Mine operation in 1981 until a cessation of operations that began hi
early 1986, the facility operated a vat leach system. As noted previously, Silver State Mining
Corporation was the original owner/operator; Nerco became the operator in 1984 when it purchased
Silver State (Silver State 4/13/84, MLRD 6/20/84).
Ore from the Ironclad pit was crushed to 0.5 to 1.0 inches in diameter. Portland cement was added
at a rate of about 10 pounds per ton of ore and a concentrated solution of sodium cyanide and caustic
soda (concentrations were not provided but the reagents amounted to about one percent by weight)
was also added. Cement and reagents were added to the ore in an agglomerating drum. Ore was
then conveyed to a stockpile hi the Victor Mill building, from which it was transported by loader to
one of four 1,000 ton indoor vats (each 80 x 50 x 9 feet). The vats were constructed of 9.5 inch
rebar-reinforced concrete and had a sloping base to facilitate loading and unloading. Rubber
waterstops were used to fill concrete joints and the insides of the vats were periodically re-sealed with
epoxy. (MLRD 9/8/81, Lewis 1982, and Nerco 4/25/85)
4-24
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Site Visit Report: Nerco Minerals Cripple Creek
Once placed in a vat, ore was saturated with a solution containing 2.5 pounds of sodium cyanide per
ton of solution (0.1 to 0.12 percent free sodium cyanide). Pregnant solutions drained through the ore
into sumps, then were pumped to the processing facilities elsewhere in the mill building. After
leaching, but before removal from vats, ore was rinsed with fresh water and drained for at least two
hours, after which time the "tailings" were removed by front-end loader and placed on a conveyor,
which carried them to the tailings pile. On the pile, a bulldozer or loader spread tailings on the top
and over the advancing face of the pile. Unloading and conveyance gave the tailings another four to
six hours to drain residual solution. The vats operated on three- or four-day cycles and at any given
time, two vats would be leaching while the other two were being loaded or unloaded. Gold
recoveries were said to be about 83.6 percent. (MLRD 9/8/81, Lewis 1982, Nerco 2/12/86)
The spent ore, or tailings, was placed in free-standing tailings piles, one (area 1) immediately to the
* >
north of the mill building and a second (area 2) across Range View Road immediately to the
northeast. The piles were lined with 20-mil PVC and surrounded by berms. In some areas, the liner
was placed on 12 inches of fine-grained (but otherwise undescribed) material; in later years, a 90-mil
(300-grade) geotextile fabric was substituted as an underlayer. Drainage from at least some areas of
the piles was facilitated by four-inch pipes installed over the liner. (Silver State Mining Corporation
3/25/81 and 5/24/83; MLRD 9/8/81 and 2/26/87; Nerco 5/9/85 and 1/6/87) An extension of tailings
area 1, located partially on top of the old Globe Hill heap, also was planned, but apparently was
never implemented (Nerco 6/19/84, 4/25/85, and 2/12/86; MLRD 6/11/85).
Tailings, which were dumped at their angle of repose, were set back about 12 feet from a berm that
was (or is) four feet high. The liner extended out from the toe of the pile to the top of the berm, and
this area served as a seepage/run-off collection ditch; in the downhill corner, a larger area served as a
collection pond. As the tailings area advanced downhill and the liner was extended, the collection
ponds were advanced as well. Thus, as the tailings piles changed configurations over tune, the
collection ponds also changed locations and sizes. This culminated in most of area 1 draining to a
permanent pond some distance downhill from (and north of) the tailings; this pond was lined with 36-
mil Hypalon. This pond, known as pond 4A, was later enlarged and relined for use as the pregnant
solution pond for the new Ironclad heap leach (see section 4.3.5.2). (Silver State Mining Corporation
3/25/81; MLRD 9/8/81 and 2/26/87; Nerco 2/12/86 and 1/6/87) In 1987, during the extended
shutdown, a second Hypalon-lined pond was constructed below the first one and provided additional
capacity; this pond became Pond 4B, as described in 4.3.5.2 below (Nerco 9/87, 5/10/91).
A portion of. area 1 drains to pond 1 South, which is located inside the surrounding berm; the size
and capacity of this pond were not determined. Ponds 2 South and 2 North (of undetermined size and
capacity) receive drainage from area 2. How solutions in the ponds were managed prior to 1984 was
not determined (i.e., whether processed for gold recovery, land-applied, or used as barren solution
makeup water). In 1984, after succeeding Silver State as the operator, Nerco indicated that solutions
would be removed "as necessary" and used as process water (Nerco 6/19/84).
4-25
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Site Visit Report: Nerco Minerals Cripple Creek
Following Nerco's assumption of the Victor Mine permit (81-134), solutions in the tailings collection
ponds were sampled for pH and cyanide monthly and for a full suite of parameters annually. Table
4-3 presents sampling data. It should be noted that no additional tailings were added to the tailings
piles after the end of 1985 or early 1986. Thus, samples do not reflect drainage from fresh tailings
but rather precipitation infiltration and run-off from "old" tailings. Table 4-4 presents the results of
samples of solutions taken when the vat leaching operation was active; in addition, the table presents
results from single samples of fresh (within a few days of vat leaching) and aged (over 18 months
after disposal) tailings solids that were taken in 1984. The fresh tailings were also subjected to an
Extraction Procedure (EP) Toxicity test.
In mid-1985, the facility re-opened after a major expansion, during which four 2,000-ton vats (100 x
65 x 9 feet each) were added to the existing four 1,000-ton vats in the Victor Mill building (Nerco
%
2/12/86). Ore tonnages steadily increased (from and to unspecified levels) after July 1985 (Nerco
10/28/85). On November 6, 1985, the face of area 1, which was advancing northward with an acute-
angled face (as the area between the Globe Hill heap and Range View Road, between which the
tailings pile was advancing, narrowed), collapsed and sloughed into the collection pond. This led to
an escape of about 125,000 gallons of cyanide solution. 'It also led to a number of proposed changes
hi tailings pile construction and configuration. These included reducing the design height from over
250 feet to 150 feet and constructing the pile hi lifts with periodic benches. (Nerco 2/12/86 and 3/20-
24/86; MLRD 1/2/86, 2/20/86, and 3/25/86) Although MLRD had requested in 1984 that final
slopes be no greater than 3H:1V, a subsequent geotechnical study by Nerco's consultant led to MLRD
approval of 2H:1V final slopes (Nerco 6/19/84, Dames & Moore 1984).
In January 1986, shortly after the tailings slough, the facility entered an extended period of inactivity.
In 1990, Nerco applied to remove the temporary cessation notice. Plans were to conduct site
preparation work within the approved tailings pile area and begin laying liner material to extend the
pile. .Although not explicitly described, Nerco presumably intended to re-activate the vat leaching
operation and continue use of the (modified) tailings pile. (Nerco 9/17/90) However, the facility's
vat leaching operation was not re-activated, since approval of the application to resume operations
was not granted until October 29 (after the construction season) and Nerco in May 1991 submitted
plans for a change from the vat leaching operation to a heap leach system. (MLRD 10/29/90, Nerco
5/10/91).
Tailings area 1 was permitted to cover over 11 acres-the actual area used was not determined.
Apparently, this included the area of the Globe Hill heap that was to be covered with tailings
beginning in 1985. (Silver State Mining Corporation 3/25/81; MLRD 7/1/85) The total volume or
weight of tailings that were generated by the facility and that are currently located on the site was not
determined.
4-26
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-3. Concentrations of Selected Parameters in Tailings Collection Ponds
(units are milligrams per liter except as noted)
' ' faaaaaa^ef'''^- ^
T 10/30/87
9/10/88
9/15/89
8/23/W
Pond4A»
pH(s.u.)
TDS
Total CN
FreeCN
Radium 226 (pCi/L)
Nitrate
Arsenic
Copper
Lead
Silver
Zinc
9.31
474
0.61
0.02
9.4
11.5
0.028
0.55
0.68
0.05
0.93
9.97
520
0.006
< 0.1
-
6.95
0.024
0.28
0.6
0.01
0.85
9.69
444
0.131
< 0.05
15 ,
7.0
0.033
0.26
0.59
< 0.01
0.75
8.6
550"
0.1
< 0.1
8.2
0.19
0.006
0.053
0.019
0.0003
0.072
Pond 4B1
pH (s.u.)
TDS
Total CN
FreeCN
Radium 226 (pCi/L)
Nitrate
Arsenic
Copper
Lead
Silver
Zinc
9.58
440
0.51
0.01
8.9
14.7
0.013
0.44
0.48
0.05
1.02
8.48
348
0.051
< 0.1
-
7.63
0.015
0.18
. 0.25
0.01
0.39
8.35
385
0.068
< 0.05
7.8
8.1
0.017
0.27
0.61
< 0.01
0.51
8.3
360b
0.046
< 0.1
3.3
2.0
< 0.005
0.039
0.031
0.0003
0.082
(continued)
4-27
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-3. Concentrations of Selected Parameters in Tailings Collection Ponds (continued)
Parameter
pH (s.u.)
IDS
Total CN
Free'CN
Radium 226
(pCi/L)
Nitrate
Arsenic
Copper
Lead
Silver
Zinc
10/30/87
9/10/88
9/15/89
8/23/90
Pond 1 South1
9.03
666
0.4
0.04
15
(+/- 4)
11.2
0.024
0.38
0.54
0.02
1.02
9.45
400
0.559
< 0.1
-
4.14
0.054
0.27
0.85
0.01
1.22
10.0
636
0.299
0.14
12
.(+/- 4)
. 1.32,
0.056
0.26
0.69
0.01
0.87
10.1
780"
0.54
0.14
16
(+/-D
< 0.05
0.042
0.35
0.64
0.0016
0.94
Pond 2 South*
pH (s.u.)
IDS
Total CN
FreeCN
Radium 226
(pCi/L)
Nitrate
Arsenic
Copper
Lead
Silver
Zinc
9.83
486
0.10
0.03
0.0
(+/- 0.7)
5.82
-------
Site Visit Report: Nerco Minerals Cripple Creek
Table 4-3. Concentrations of Selected Parameters in Tailings Collection Ponds (continued)
Parameter ;
pH (s.u.)
TDS
Total CN
FreeCN
Radium 226
(pCi/L)
Nitrate
Arsenic
Copper
Lead
Silver
Zinc
; 10/30/87
9/10/88
9/15/89
8/23/90
Pond 2 North1
9.00
828
0.27
0.13
0.0
(+/- 0.7)
14.4
0.015
0.43
0.07
0.03
0.28
9.45
552
1.08
0.4
9.83
0:019
0.69
0.22
0.05
0.38
9.57
644
0.436
0.29
1.0
(+/- 1-2)
12.5
0.005
0.39
0.17
0.02
0.37
8.1
520"
0.44
0.2
4.0
(+/- 0.4)
3.4
0.0005
0.049
0.10
0.0003
0.022
NOTES:
a These ponds receive run-off and precipitation-induced drainage from tailings areas 1 (ponds 4A, 4B, and 1
South) and 2 (ponds 2 South and North). No tailings have been placed in either area since early 1986. Area
2 has been under reclamation since 1988. Ponds 4A and 4B now receive pregnant solution from the Ironclad
heap leach pad.
b Believed by Nerco to be in error due to paniculate passing through filter.
Source: Table G-l in Nerco 10/19/90 (1990 Annual Report to MLRD).
Table 4-4. Concentrations of Selected Constituents in Vat Leach Tailings and
Tailings Seepage Ponds
Analyte H
PH
Free cyanide
Total cyanide
.Cadmium
Copper
Lead
Mercury
Nitrate
Silver
Tailings Seepage Ponds 1-4
: (mg/1 except pB)
9.36 - 9.85 s.u.
0.97 - 16.9
1.41 - 19.3
< 0.01 - 0.07
0.31 - 4.40
< 0.01 - 0.03
0.0008 - 0.0101
3.57 - 8.89
0.06-0.12
Aged and fresh Tailings*
(ppm except as noted)
9.15 -9.18 s.u.
1.8-4.5
2.1 -5.2
< 10
110 - 170
460 - 510
0.33 - 0.87
Not analyzed
0.13-0. 19 oz/ton
* The first (lower) concentration represents a single sample of aged tailings; the second (higher) represents a single
sample of fresh tailings.
Source: MLRD 7/1/85 (attachment to Newport Minerals application for Permit 77-367, Amendment 5)
4-29
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Site Visit Report: Nerco Minerals Cripple Creek
Original reclamation plans (in 1981) called for the tailings piles to be rough-graded and left with a
"mining area flavor," with revegetation left to nature. The disturbed area around the tailings piles
was to be revegetated. (Silver State Mining Corporation 3/25/81) Subsequently, MLRD added the
requirement that the tailings piles be reclaimed at closure by regrading and revegetation. The
operator at the time, Silver State Mining Corporation, was to establish a number of test plots to aid in
reclamation planning. (Silver State 5/26/83). Once they assumed the permit in 1984, Nerco's
proposed reclamation was similar. Nerco began reclamation of area 2 hi 1985, when the entire area
was graded to a slope of 2H:1V and fenced (Nerco 10/28/85). In 1988, Nerco established test plots
for the revegetation of area 2 (Nerco 9/88). Through 1990, at least some aspens and other trees had
survived, and Nerco had identified at least 15 forb and five grass species that had established
themselves by "natural seeding" (Nerco 9/88, 9/89, and 10/90). The south and east sides of tailings
area 1 were graded to 2H:1V hi 1985, and test plots were established on this pile using Soil
Conservation Service (SCS) rootstock (Nerco 10/28/85). In subsequent years,"the area 1 test plots
were described hi the 1986 annual report as "disappointing" (Nerco 1/6/87) and in the 1987 report
(Nerco 10/13/87) as having "zero results." According to Nerco, the SCS concluded that the rootstock
had been dead at the tune of planting.
In 1991, in its application to add the Ironclad heap leach pad to the Victor Mine permit, Nerco
indicated that the rest of tailings area 1 would be graded to a 2H:1V slope. Nerco was formulating
plans to bench the pile at 20- to 25-foot elevations, load the benches with a growth medium, and
establish vegetation on the benches. In addition, Nerco indicated that Ironclad pit expansion would
require moving about 90,000 tons of tailings from area 1 to an unspecified location. (Nerco 5/10/91)
The current reclamation status of tailings areas 1 and 2 was not determined.
4.3.5 Ironclad Heap Leach Pads and Ponds (Permit 81-134)
In 1991, Nerco began construction of what will become a single 1.5 million square foot heap leach
pad served by three solution ponds. Construction is to occur hi three phases, with subcells and pads
completed hi early phases placed hi operation while construction continues on subsequent phases.
Figure 4-5 shows the location of the pad and the phases of construction. Part or all of two of the
phases had been completed and were being actively leached by early 1992. The entire heap leach pad
is known as the "Ironclad" pad. It should be noted that the descriptions of pad and pond construction
hi the following subsections are not based on "as-built" engineering reports but rather on permit
applications and other MLRD and Nerco correspondence. Section 4.3.5.1 below describes the
"Ironclad" pad, while solution ponds serving the heap leach pad are described hi 4.3.5.2. Section
4.3.5.3 describes other wastes and materials managed by the facility.
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Site Visit Report: Nerco Minerals Cripple Creek
Figure 4-5. Location and Phases of Construction of the Ironclad Heap Leach Pad
(Source: Nerco 5/10/91, with additional labels added by EPA)
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4.3.5.1 Heap Leach Pads
Phase I Pad
The Phase I pad, completed in 1991, is located immediately to the north of tailings area 1. Figure
4-6 shows the planned final configuration of the-Phase I pad and heap. The pad covers nearly
375,000 square feet and is surrounded by a three-foot berm. The pad, surrounding ditches, and the
inner slope of the berm are all double-lined: the liner system consists of an 80-mil HDPE primary
(upper) liner and a 60-mil HDPE secondary (lower) liner. A geonet layer, which connects with a
series of wick drains that serve for leak detection, lies between the liners. The underlying surface
consists of six or more inches of soils compacted to 90 to 95 percent (according to Nerco, the
compaction should result in a permeability of less than 1 x 10* centimeters per second). The
secondary liner lies on this prepared surface. Internal divider berms underlie the liner system and
serve to divide the pad into 80,000 square foot subcells. These divider berms are three feet high with
1.5H:1V side slopes. The leak detection wick drains are installed between the liners along the
upslope sides of the berms; the pregnant solution collection pipes (eight-inch slotted HDPE) are on
top of the primary liner, again on the upslope sides of the berms. Figure 4-7 shows liner and internal
divider berm construction. The Phase I pad is designed to hold about 800,000 tons of ore prior to
becoming part of the larger Ironclad pad. (Nerco 5/10/91)
A solution collection ditch extends along the east side of the pad; the ditch is 12 feet wide and two
feet deep and lined as described below. To the south, the liner was to be shingled under the existing
20-mil PVC liner that drains tailings area 1 (Nerco 5/10/91). The amendment (i.e., the application
by which Nerco requested permission for the new construction and which was approved by MLRD)
does not mention ditches on the west or north. The south and west are slightly uphill and the north
side 4s to be joined to the full-sized pad during Phase HI of construction. During the site visit, Nerco
indicated that the shingling of the Phase I liner under the tailings liner was not successful, and that
trench drains were actually used to drain the tailings. Details qn these drains (and how and where
tailings drainage is conveyed), and on how the south end of the Phase I pad actually is constructed.
were not determined. Although all sides were to be bermed, available documents d6 not mention
collection ditches on any side but the east. (Nerco 5/10/91)
Ditch liners are part of the overall pad liner system described above. The pad liner extends across
the ditch and up the inner slope of the three-foot outer berm, in which it is anchored hi a two foot
trench (a total of 12 feet across the ditch to the inner edge of the berm and four feet up to the anchor
trench) (see Figure 4-7). The collection ditch receives fluids from the pregnant solution drain pipes
and from two-inch pipes that drain the geonet and wick drains; the ditches convey the solution to
Pond4A. (Nerco 5/10/91)
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Site Visit Report: Nerco Minerals Cripple Creek
Figure 4-6. Planned Final Configuration of Phase I Portion of Ironclad Pad
(Source: Nerco 5/10/91, with additional labels added)
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Cripple_Cr*ek
COLLECTS D.TCH * REIEKIK>N BERM SECTION
DETAIL OF DOUBLE LINER
AND
INTERNAL DIVIDER BERM
80 ML HOPE
CEONET OWUNACC
AMEfVORAm
WCK DRAW
OK EOUIV.
«. *^^^«**e*mcaa!*m*m
(Source: Nerco 5/10/91)
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Sire Visit Report: Nerco Minerals Cripple Creek
According to the amendment, ore is stacked on the pad no closer than "15 to 20 feet from the edge of
the liner" (whether this was to be measured from the inner edge of the ditch or from the anchor
trench was not specifiedin the latter case, ore would be stacked to the ditch's edge) (Nerco
5/10/91).
The approved amendment application in which Nerco described the Ironclad heap construction did not
specify heap neutralization or reclamation requirements (Nerco 5/10/91).
Phase n Pad
Phase n of the construction, which was initiated and partially completed in 1991, will add an area of
669,557 square feet of lined pad when complete. This area is north of the present Globe Hill heap
and immediately to the west of the pregnant solution pond (Pond 4A). The liner system, internal
divider berms, and ditches were to be the same as for Phase I construction, with collection ditches
along the north and east sides of the pad; the ditches drain to Pond 4A. The amendment did not
mention whether berms would be constructed around the Phase n pad. (Nerco 5/10/91) The portion
of this pad nearest the pregnant solution pond had been completed and was in operation by February
28, 1992, since a 30-foot lift sloughed into the collection ditch on February 29, as described hi
section 4.4.5.8 (MLRD 3/2/92). Overall, the Phase n portion of the pad is designed to hold about
1,300,000 tons of ore before it becomes part of the full-sized "Ironclad" pad. Figure 4-8 shows the
planned final configuration of the Phase n pad.
The Forest Queen/2A heap leach pad (which is hi the area covered by Permit 77-367) currently
occupies western portions of the Phase n pad area. As noted above, it is constructed on the surface
of the Globe Hill waste rock dump. The permit amendment authorizing the phased construction of
the new Ironclad pad indicated that the Forest Queen/2A pad was to be "detoxified," then graded to
the north and east (i.e., toward the pregnant pond area) (Nerco 5/10/91). The previous Globe Hill
permittee (Dayspring Mining) reported to MLRD in 1988 that neutralization of the Forest Queen pad
had been completed (Dayspring Mining Corporation 3/17/88). It is not clear if MLRD ever accepted
this assurance. During the site visit, Nerco indicated that the heap would be rinsed with water, and
possibly an oxidant, until cyanide levels were below 0.2 ppm; when this is accomplished, the
"detoxified" spent ore will be placed on the waste rock dump. It was not determined if this
detoxification had begun or had been completed (or would be necessary, as described hi section
4.3.3.2), or when the Phase n construction would reach the area where the Forest Queen/2A pad is
located.
Phase m Pad
Phase m of pad construction was planned to be completed in 1992. This phase requires lining the
463,488 square foot area between the Phase I and II pads. Part of the Phase in pad is to be located
where the old Globe Hill heap leach pad is located. Liners and other construction are to be the same
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Figure 4-8. Planned Final Configuration of Phase II Portion of Ironclad Pad
(Source: Nerco 5/10/91, with additional labels added by EPA)
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Site Visit Report: Nerco Minerals Cripple Creek
t
as described above for Phase I; liners for the Phase in area will be joined to the Phases I and n liners
to make a single 1,500,000 square foot pad. The Phase ffl portion of the pad will hold 2,300,000
tons of ore. The Phase I and n heaps will join the Phase in heap and become a single heap that
ultimately will contain about 4,400,000 tons of ore. Figure 4-9 shows the planned final configuration
of the Ironclad Jteap when all phases of construction are complete.
Because the downhill portions of the Phase in pad (north and east) will be joined to earlier
construction, collection ditches are not possible for the Phase HI portion of the pad. According to the
amendment, solution from the Phase III pad is to.be collected by a "collection pipe" along the east
edge of the Phase HI pad where it joins the Phase I pad. Presumably (although this was not
described) the same configuration will be used on the north side, where the Phase in and Phase n
pads will join. The pipes in these areas will be on the liner underneath the heaps and will convey
pregnant solution to Pond 4A. (Nerco, 5/10/91) The size of these pipes and the means by which
they will be joined to the eight-inch pipes that drain the pad subcells were not described.
As with Phase n construction in the old Forest Queen pad area, Phase HI will require the old Globe
Hill heap to be "detoxified" and graded to the north and east (Nerco, 5/10/91). During the site visit,
Nerco indicated that the old heap would be rinsed with water, and possibly an oxidant, until cyanide
levels were below 0.2 ppm; when this is accomplished, the "detoxified" spent ore will be placed on
the waste rock dump. It was not determined if rinsing would actually be necessary, or if it had been
initiated or completed at the .time of the site visit.
Leaching Operations
Ore is stacked on operating pads via a conveyor from the crusher. At any given time, a solution of
80 to 100 ppm sodium cyanide is applied (via drip irrigation) at 400 gallons per minute to one or
more 80,000 square foot subcells (a rate of 0.005 gallons per minute per square foot). The length of
time each cell will be leached was not determined.
Although not described in permit applications, ore is to be stacked on the heaps to over 100 feet
(based on contour maps provided by Nerco). Ore is stacked in 20- to 30-foot lifts (during the site
visit, Nerco indicated 20-foot lifts were used; during an inspection report, MLRD jeported a 30-foot
lift had failed (MLRD 3/2/92), so lift heights may be variable). Phase I and n pads will have
separate heaps which will be joined as the Phase III heap rises between them.
As noted in chapter 4.2, mined ore has a moisture content of about four percent by weight. This is
raised to six percent when a cyanide solution is applied to ore on the conveyor to the heap. Ore
being actively leached has a moisture content of about 15 to 18 percent by weight. After active
leaching is concluded, fully drained ore is expected to retain about 10 percent moisture by weight
(Nerco 5/10/91).
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Site Visit Report: Nerco Minerals Cripple Creek
Figure 4-9. Planned Final Configuration of Ironclad Heap Leach Pad
(Source: Nerco 5/10/91, with additional labels added by EPA)
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Solution from the Phase I and II areas of the pad (and possibly drainage collected hi french drains
downhill of tailings area 1) enters the appropriate collection ditch and is conveyed by gravity to the
pregnant solution pond (Pond 4A). As described above, solution from the Phase HI portion of the
pad will be conveyed to the pond area via a pipe under the heap. (Nerco 5/10/91)
4.3.5.2 Solution Ponds
Three ponds provide primary containment for process fluids and precipitation. They have a combined
capacity of 10,500,000 gallons. Each of the ponds is described separately below. Together, they are
designed to contain (Nerco 5/10/91):
Total run-off from their drainage areas of six days of 0.1 inch precipitation per day plus
' the 100-year/24-hour storm event, an additional 3.5 inches (a total of 4.1 inches of
precipitation, or 5,375,200 gallons)
Three days' pregnant solution discharges from actives areas of the heap(s) in the event of
pump failure (1,728,00 gallons), and
Normal working volumes of pregnant solution (2,000,000 gallons).
Pond 4A
Originally constructed hi 1986, this pond was a Hypalon-lined run-off collection pond for tailings area
1 (Nerco 1/6/87). The pond was enlarged hi 1991 to serve as the primary pregnant solution pond for
the new Ironclad heap leach pad. The pond was enlarged to 150 feet wide, 302 feet long, and
excavated hi bedrock to a depth of 25 feet. The south end is sloped at 3H: IV and the other sides at
2H:1V. The pond's capacity is 5,000,000 gallons. The pond has two 60-mil synthetic liners over a
compacted surface, with a geotextile leak detection system between the liners. There is a sump
between the liners near the upper end of the pond, to which any fluids in the leak detection layer
drain; fluids hi the sump (and thus any leakage hi the primary upper liner) are monitored from a leak
detection manhole, connected to the sump by a four-inch pipe, on the north end of the pond. (Nerco
5/10/91)
The pond is surrounded by a three-foot-high berm that also is lined. Pregnant solution reaches the
pond from lined collection ditches at the bases of the Phases I and n portions of the pad, and will
come through pipes (see section 4.3.5.1 above) from the Phase in portion of the pad. (Nerco
5/10/91). The ditches (and presumably the pipes in the future) lead to a stilling basin immediately
upgradient of the pond's north berm. This basin serves to slow the flow of pregnant solution before
it enters the pregnant pond and also allows excess flow to be diverted to Pond 4C, the emergency
overflow pond. The stilling basin is triple-lined; besides a double liner of 80-mil HDPE, a third layer
of 80-mil HDPE is intended to enhance the pond's resistance to wear. Details on the basin's leak
detection system, if any, were not available. From the stilling basin, solution formerly entered a six-
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Site Visit Report: Nerco Minerals Cripple Creek
inch PVC pipe, which passed through the Pond 4A liners (and was sealed to the basin's and pond's
liners) into pond 4A; excess flow was directed through a similar pipe to Pond 4C. (MLRD 2/27/92
and 3/2/92) In early 1992, following a spill of pregnant solution, the means of conveying solution to
Pond 4A was changed from the PVC pipe to a double-lined open trench after it was determined the
transmittal pipe to Pond 4C had not been properly sealed to the basin's secondary liner (Nerco
3/6/92).
Pregnant solution is pumped from Pond 4A (and as necessary from the other ponds) at about 250 to
400 gallons per minute to the carbon-in-leach circuit(s) in the mill building.
Pond4B
This pond was originally authorized by the approval for Technical Revision 4 "and was constructed in
1986 (Nerco 3/10/86; MLRD 2/20/86 and 3/25/86). The pond is immediately below Pond 4A and
originally served as a second tailings run-off collection pond. It now serves as an overflow pond for
Pond 4A, the pregnant pond (Nerco 5/10/91). Pond 4B was excavated from bedrock in 1987. It was
160 feet long, 145 feet wide, and 25 feet deep, with a total capacity of 1,500,000 gallons. It was
constructed with a geotextile underliner and 36-mil Hypalon liner. A 36-mil Hypalon-lined ditch
conveys excess pregnant solution from Pond 4A to this pond. (Nerco 10/13/87) Pregnant solution
from this pond is pumped back to Pond 4A when necessary.
Pond4C
This pond was constructed hi 1990 as an emergency overflow pond. The pond has a total capacity of
4,000,000 gallons. Like pond 4A, the pond is double-lined (two 60-mil HDPE liners) with a
geotextile leak detection system between liners. The pond receives excess solution that cannot be
accepted by die pregnant pond (Pond 4A). (MLRD 5/10/91) Pregnant solution from this pond is
pumped to Pond 4A when needed.
4.3.5.3 Wastes and Other Materials Managed by Nerco
As noted above, gold recovery operations (from carbon-in-column circuits through dore" production)
take place hi the Victor Mill building. This building contains the vats from the former vat leaching
operation (see section 4.3.4) and has a concrete floor. The various tanks hi the building (barren
solution tanks, two operational series of portable carbon columns, caustic wash tanks, etc.) are
surrounded by low concrete curbs for secondary containment. Some drams were observed during the
site visit but it was not determined if they were individual sumps or if they drained to a central
location.
All chemicals used on the site are stored hi this building. These include unspecified amounts of
sodium cyanide (in reusable flow-bins), Milsperse surfactants (in 20-50 pound plastic sacks), and
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Site Visit Report: Nerco Minerals Cripple Creek
acids and caustic (in unspecified containers). In addition, an unspecified amount of calcium
hypochlorite is stored in the building for use in neutralizing any spills of cyanide solution that may
occur. The more hazardous materials are stored in a fenced area within the building.
Maintenance on Nerco's seven haul trucks, three loaders, two drills, and other vehicles and
equipment is conducted in a vehicle maintenance shop near the Victor mill building. Fuel oils and
gasoline, hydraulic and lubricating oils, antifreeze, and other materials that are used on-site are stored
hi or near the mill and maintenance buildings; the amounts used and stored and the means of storage
were not determined. Some used oil is used to fire two space heaters in the Victor Mill building; the
remaining used oil is transported off-site by a contractor for recycling or disposal. The volumes of
used oil burned and shipped off-site were not determined. A contractor provides Nerco with
complete tire service: the contractor provides new tires, handles tire maintenance and repairs, and
removes old tires; further information on tires was not available.
Nerco has an assay laboratory hi the Carlton mill building. The capabilities of the laboratory were
not determined. However, Nerco indicated that about 45,000 fire assays had been performed in the
previous year for the Cripple Creek operations (these would have included assays of pit blastholes,
tails solutions from carbon columns, samples from area waste rock dumps being considered as sources
of ore, and exploratory drilling samples). Cupels from these assays are stored hi 55-gallon drums but
the number of drums and the total weight/volume of cupels were not known. Nerco indicated the
cupels have high (but unspecified) levels of lead and that they were actively searching for a market,
but had been unsuccessful to date. The laboratory also generates an unspecified amount of liquid,
which are piped to the Carlton Mill pregnant ponds.
Nerco purchases five to seven million gallons of water from the town of Victor each year. The water
comes from two reservoirs operated by the town and is purchased prior to the town's chlorination
treatment (since the chlorine would interfere with leaching). Bottled water is used for potable water.
According to Nerco, most of the water purchased from the town is used for drilling and for dust
suppression hi the mining area and on haul roads. No surfactants are added to the dust suppression
water, although that was described as possibly being necessary in the future. Some unspecified
quantity of the purchased water also is used as makeup water for barren solution, although most water
used for that purpose comes from precipitation. Nerco moves water among its Cripple Creek
operations as necessary. According to Nerco, any additional makeup water that may be necessary
comes primarily from the Pad 4 ponds (see section 4.3.6.2), which in turn comes from snowmelt as
well as excess water moved from the Pad 2 ponds (see section 4.3.6.1).
Nerco recycles paper, cardboard, and plastics from their Cripple Creek operations, and these
materials are stored in a fenced "recycling" storage area at the Carlton Mill. Proceeds from the sale
of such materials supports the local rescue squads.
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Site Visit Report: Nerco Minerals Cripple Creek
Nerco also operates two small landfills, one on the Victor Mine and one on the Lillie permit (on what
is known as the old Ajax mine property). The Department of Health delegates responsibility for
regulating landfills and other waste disposal at mining operations to MLRD, but information on these
landfills, and materials disposed in them, was not obtained. In addition, sanitary sewage from the
Victor and Carlton Mill buildings is discharged to septic fields near the mills.
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4.4 OTHER MAJOR CRIPPLE CREEK OPERATIONS
4.4.1 Carlton Mill (Pads 1 and 2)
The Carlton Mill was a conventional gold mill, using flotation for recovery. It operated from the
early 1950s until about 1962. Tailings from the mill were disposed in a series of two or more
dammed impoundments immediately below the mill in Arequa Gulch.
Cartton
In 1980, Texasgulf Minerals and Metals
(actually, Cripple Creek and Victor Gold
Mining Company (CC&V),.which at that
time was the joint venture of Texasgulf and
Golden Cycle Gold Corporation) applied for
and received MLRD permit number 80-244
to re-open the mill. Although Texasgulf
operated the mill briefly, it was not active
for long periods during the early 1980s.
Beginning in 1985, Texasgulf began
construction of what became heap leach
Pads 1 and 2 and associated solution ponds.
The sources of ore for both heaps were
abandoned mine dumps in the Cripple Creek
area. Some of these dumps were permitted
under the Carlton Mill permit and some
were permitted separately. The Carlton
Mill permit area now exceeds 137 acres, including some outlying mine dumps. Appendix A presents
a detailed history of the Carlton Mill permit. As with other Nerco permits, the Carlton Mill leach
project has expanded incrementally since its inception, with successive approvals sought from MLRD
for annual expansions.
Pad 1 is immediately uphill of the upper Carlton Mill tailings impoundment. Pad 1 was constructed
beginning in 1985 and was actively leached through 1988 (and possibly after that time, although
available documents were not clear). The pad is double-lined, but the liner materials were not
described. The heap covers about 267,000 square feet and is divided into four cells by internal
berms. A trench drain system (otherwise undescribed) was installed below the lower liner in order to
lower the water table. (CC&V 3/12/85) After the 1987 leaching season (active leaching occurred
only hi warmer months, six to eight months per year), the heap contained about 330,000 tons of ore.
which had been placed in lifts 10 to 22 feet high. The total height was 40 to 50 feet. (CC&V
3/12/85, 11/20/87) During the site visit, Nerco indicated that Pad 1 now contains about 500,000 «N»
of spent ore and that they do not plan to add additional ore to the heap.
by Nerco during site visit (relabeled)
Provided
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Four solution ponds are located immediately below Pad 1: a barren pond, intermediate pond,
pregnant pond, and another pond for solution storage. All these ponds are double-lined (again, the
liners were not described) and have a combined capacity of 3,000,000 gallons. Solution was sprayed
onto an active cell of Pad 1 by sprinklers at rates of about 250 gallons per minute; solution was then
collected in the intermediate pond. It was then applied to another cell and collected hi the pregnant
pond. Gold recovery was accomplished hi a four-tank carbon-in-column series (apparently the same
as described above for the current Ironclad/Globe Hill operations). Loaded carbon was removed to
the Carlton Mill building, where gold was recovered with pressure caustic stripping, electrolytic
plating onto stainless steel wool cathode, and smelting in a furnace to produce dore. Available
information did not describe the gold recovery process further. Barren solution from the mill was
then refortified with cyanide in the barren pond and re-applied to the heap. (CC&V 3/12/85,
11/20/87)
%
In early 1988, CC&V received approval to rehabilitate portions of the Carlton Mill and to install a
carbon-in-leach gold recovery circuit so the facility could beneficiate high-grade ore in the mill.
Tailings disposal was to occur on Pad 1: an unlined "pond" was to be excavated on the surface of the
heap for tailings disposal. A total of 25,000 dry tons of tailings were to be disposed hi this manner,
hi a slurry consisting of 45 percent solids. Geotechnical studies showed that the fine tailings (80
percent less than 325 mesh) would not migrate into the leached ore on the heap, but that water would;
this water, after leaching through the heap, was to be collected hi one of the solution ponds for
recycle to the mill. (CC&V 11/20/87; MLRD 1/25/88) It is not known if the carbon-in-column
circuit was ever completed or if tailings were actually disposed on the Pad 1 heap. During the site
visit, Nerco indicated that Pad 1 contained about 500,000 tons of spent ore, but did not mention
tailings.
Pad 2 was permitted in 1986. This heap leach pad is constructed immediately below Pad 1 on top of
the upper Carlton Mill tailings impoundment. The tailings on which the pad was constructed ranged
from seven feet deep near the upper end to 74 feet at the dam (which is known as Dam 1). The
tailings are saturated below a depth of about 30 feet near the center and 45 feet near the dam. The
pad was constructed by placing an 80-mil HDPE liner directly on the surface of the old tailings.
Geotechnical studies showed that the tailings would support the heap, although the tailings (and thus
the liner and heap) were predicted to settle about three feet near the center of the heap. (CC&V
1/16/86; Dames and Moore 1986; MLRD 3/24/86) In 1988, Pad 2 was expanded up an adjacent
hillside to a total of 440,820 square feet (CC&V 2/23/87a, 2/22/88; MLRD 2/9/88, 2/26/88) It was
not determined if Pad 2 was further expanded after 1988.
A fifth pond (Pond 5) was constructed immediately below Pad 2 but within the area of tailings (i.e.,
above the tailings dam) to serve as the pregnant pond for the pad. This double-lined (otherwise
undescribed) pond was excavated into the tailings; it covers about 42,000 square feet and has a
capacity of about 2,120,000 gallons. One of the four Pad 1 ponds serves as the barren pond for this
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Site Visit Report: Nerco Minerals Cripple Creek
heap. An additional 827,000 gallons of solution storage capacity is provided by the lined area
between the Pad 2 heap and Pond 5. Another 2,400,000 gallons can be stored on the unlined tailings
surface up to the crest of Dam 1. In 1987, an additional 3,500,000 gallons of capacity was obtained
by improving the crest of the dam on the lower Carlton Mill tailings impoundment (dam 2); this
emergency storage area is unlined. (CC&V 1/16/86, 2/23/87a; Dames & Moore 1986; MLRD
3/23/87, 1/25/88) Total Pads 1 and 2 solution storage capacity exceeds 11,000,000 gallons, sufficient
to contain normal working volumes, flow from the 100-year/24-hour storm event, and at least some
heap drainage (CC&V 3/16/89).
During the site visit, Nerco indicated that Pad 2 contained about 2,000,000 tons of ore and that
additional ore would be placed on the heap during the 1992 leaching season. Nerco also indicated
that excess water from Pad 2 ponds (presumably during the idle whiter season and spring snowmelt)
%
may be transported to the Victory Project (see section 4.3.6.2 below) for storage. Whether Nerco
uses run-off and drainage solutions collected hi Pad 1 ponds as makeup water for Pad 2 or still
recovers gold from it was not determined.
MLRD requires Nerco to monitor water quality hi Arequa Gulch upstream and downstream of the
tailings impoundments and heaps. Nerco also samples the french drain under Pad 1. Monitoring
results from 1987 through 1989 are presented hi Table 4-5. In addition, there are six "ground-water"
monitoring wells; these wells are driven into the tailings near the base of Dam 1. The only analytical
data other than pH and cyanide was for a sample from well PZ-6 on April 6, 1989; results are hi
Table 4-5.
4.4.2 Victory Project (Pads 3 and 4)
Beginning hi 1986, Texasgulf Minerals and Metals (through Cripple Creek and Victor Gold Mining
Company (CC&V), which at that tune was the joint venture of Texasgulf and Golden Cycle Gold
Corporation), constructed and operated the major components of the Victory Project: two heap leach
pads and an open pit. The permitted area covers 112 acres and is located on a ridge of Battle
Mountain about 1.5 miles southwest of the Victor/Globe Hill area and about 0.5 miles north of the
town of Victor. Much of the project area was covered by tailings and waste rock from historic
operations, and these materials underlie some of the modem operations. With Nerco's purchase of
Texasgulf hi 1990 (Texasgulf was renamed Pikes Peak Mining Company), Nerco assumed
responsibility for the permit (MLRD permit 86-024). Cripple Creek and Victor Gold Mining
Company (CC&V) has managed the site since its inception. A detailed permit history of the Victory
Project is presented hi Appendix 4-B.
i
In 1986 and 1987, CC&V constructed Pad 3, a double-lined pad that covers about 280,000 square
feet. Compacted tailings from an historic operation served as the lower liner, and an 80-mil HDPE
secondary liner was placed over that. The base of the pad is sloped an average of about 10 degrees.
with a 20 degree maximum slope in any one area. The source of ore for this pad was waste rock
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Table 4-5. Monitoring Results from Pad 1 French Drain and from Arequa Gulch Upstream and
Downstream of Pads 1 and 2
(milligrams per liter, unless otherwise indicated)
Parameter
Flow or Discharge
PH (s.u.)
IDS
Total CN
FreeCN
Nitrate (as N)
Sulfate (as SOJ
Cadmium0
Copper*
Lead'
Silver*
Zincc
Minimum and Maximum Concentrations
1987 - 1989
French Drain below
Ponds 1-4
1-8 gpm
6.6 - 7.89
850 - 860
0.039 -0.821
0.019 - 0.82'
6.6
350-440
< 0.005
0.030 - 0.47
< 0.005 - 0.0033
< 0.0002 - 0.017
0.028 - 0.38
Arequa Gulch
Upstream
0 --63 gpm
4.32-5.1"
1,100
< 0.005 - 0.065
< 0.005 - 0.013
NR
450 - 970
0.015 - 0.021
0.024 - 0.53
< 0.005-0.011
< 0.0002 - 0.0022
1.8 - 2.7
Arequa Gulch
Downstream
0 - 29 gpm
7.69 - 8.1"
1,400
0.008-0,1,4
0.008-0.011
NR
400 - 3,500
< 0.005 - 0.007
< 0.005 - 0.21
< 0.005 - 0.024
< 0.0002 - 0.0006
0.009- 1.1
April 6, 1989
Well PZ-6
NA "
8.8"
6,200
NR
68
NR
2,700
0.079
34
0.05
NR
10
NOTES:
NR Not reported
a Does not include 11/2/88 results, which showed free CN at 9.0, total CN at 16.0.
b Except well PZ-6, reported data are field measurements. Maximum laboratory measurement upstream showed 6.0 s.u.,
minimum downstream was 7.0 s.u.
c Concentrations of metals are of total metals. In 1990, monitoring requirements were changed to dissolved metals.
Source: Pikes Peak Mining Company 4/27/90.
from area mine dumps. (CC&V 2/21/86) In 1986, a total of 416,000 tons were stacked on the heap,
and an additional 430,000 tons were projected for 1987 (CC&V 2/23/87b, 5/26/87). During the site
visit, Nerco indicated that Pad 3 contains a total of about 1,000,000 tons of ore. -
Pad 4 was permitted hi 1987 and construction was apparently completed hi 1988. This 15-acre pad
(660,000 square feet) was designed with a capacity of 1,825,000 tons of ore. It is immediately south
of Pad 3. This heap was constructed on a prepared base of compacted tailings that were placed
partially over waste rock (both historic dumps and 600.000 tons of rock from the adjacent Portland
pit). This pad has a double synthetic liner (60-mil HOPE lower and 80-mil HDPE upper liners); a
layer of granular tailings crossed by 3-inch HDPE pipes serves as a leak detection system. In 1988,
about 672,000 tons of ore were placed on this heap in a single lift that averaged 20-25 feet deep (and
4-46
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Site Visit Report: Nerco Minerals Cripple Creek
Victory Project
*.
by Nerco fleirj0«te visit (relabeled)
ranged from eight to 30 feet, depending on
site elevation). Ore came from the Portland
Pit and from area waste rock dumps.
(CC&V 7/17/87 and 12/8/87; Dames &
Moore 3/16/89) The total amount of ore on
Pad 4 was not determined.
In constructing Pad 4 and its associated
ponds, a total of 12 old mine shafts were
discovered; the top few feet of each was
cleared out (by backhoe) and examined,
then filled with gravel and compacted.
(Dames & Moore 3/16/89) An unspecified
number of shafts had also been filled and
covered during construction of Pad 3
(CC&V 5/26/87, 2/21/86).
The Portland Pit, immediately downhill and to the east of Pad 4, was permitted in late 1987 and
developed in 1988 and 1989. As planned, the pit's dimensions were to reach 1,400 feet long (north
to south, oriented along the side of the ridge) by 500 feet wide (east to west) by 240 feet deep (near
the center). A waste rock:ore ratio of about 2.5:1 was anticipated, reaching totals of 1,300,000 to
1,500,000 tons of waste rock and 500,000 tons of ore. The actual dimensions, and the amount of
material mined, were not determined; during 1988, about 600,000 tons of waste rock from the pit
were used in preparing the base for Pad 4. (CC&V 8/12/87, Dames & Moore 3/16/89)
The Victory Project used a total of six solution ponds. A barren, pregnant, and emergency overflow
pond serve Pad 3 and parts of Pad 4; the remainder of Pad 4 is served by three more ponds (again, a
barren, pregnant, and emergency overflow pond). All of the six ponds are connected by buried and
aboveground pipes that allow pumping or gravity flow between any of the ponds. All ponds (with the
possible exception of the emergency overflow ponds) have two 60-mil HDPE liners and geotextile
leak detection systems. In addition, lined berms surrounding the ponds provide additional storage
capacity. Overall, the pond system is designed to contain flows from the 100-year/24-hour storm
event, an additional 0.6 inches of precipitation, and one day's operating volume. (CC&V 2/21/86,
2/23/87b, 5/26/87, 7/17/87, and 12/8/87; Dames & Moore 3/16/89)
Details on barren solution makeup and characteristics were not determined. Barren solution was
applied to each of the heaps via drip irrigation lines at a maximum rate of about 550 gallons per
minute; leachate from the heaps then flowed by gravity through lined ditches to the respective
pregnant ponds. Gold was recovered in portable carbon columns similar to those described in section
4-47
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Site Visit Report: Nerco Minerals Cripple Creek
4.2.3. Carbon columns with loaded carbon were transported to the Carlton Mill for gold recovery.
(CC&V 2/21/86, 7/17/87)
Reclamation requirements for the heaps include grading side slopes to an average of 2H:1V or less
and detoxification, but not revegetation. The heaps are to be rinsed until effluent is of "acceptable
quality" to MLRD. (CC&V 2/21/86; 7/17/87) Nerco indicated during the site visit that no"cyanide
solution was being applied to the heaps (the most recent time it was applied was not determined) but
that the heaps were being sprayed for water balance purposes. Nerco indicated that the heaps would
be decommissioned later in 1992. Reclamation for the solution ponds and other disturbed areas will
involve seeding and revegetation. For the Portland Pit, there will be a warning/safety bench about 15
feet below the rim and an access ramp for wildlife and trespasser exit will be left. Available topsoil
will be spread on benches and the pit floor, and grasses and trees will be established. Reclamation
plans for the pit were approved late in 1989; the status of formal planning for'other areas was not
determined. (Texasgulf 5/10/89).
4.4.3 '76 (Bull Hill) Project
Sometime prior to September 1981, Newport Minerals began cyanide leaching operations at the '76
Project (also known as the Bull Hill Project), an area about 1.5 miles southwest of the Globe Hill
site. This site, which Newport or other operators began operating in 1976, was a heap leach system
that used waste rock from area waste rock dumps as ore. On August 27, 1981, the Mined Land
Reclamation Board issued a Notice of Violation to Newport, citing the fact that MLRD had never
received or approved an application for the "mining and reclamation operations" at the site. Newport
was ordered to stop all leachmg/mining operations at the '76 site and to submit a permit application
or an application to amend the Globe Hill permit. Newport's attorneys responded that Newport
questioned whether cyanide heap leaching in general was a "mining operation" and thus subject to
permitting. In addition, Newport's attorneys questioned whether the removal of waste rock from old
dumps could be considered mining under the definition in Colorado's statutes (which referred to
removal of ore from "natural occurrences"). MLRD's position was that both activities (i.e., heap
leaching and waste rock removal) were considered mining. Notwithstanding Newport's retention of
their arguments as possible defenses, the company submitted an application to amend the Globe Hill
permit by adding the '76 site to the permitted area. The Mined Land Reclamation Board subsequently
approved the amendment. (MLRD 9/2/81 and 12/21/81; Geddes et al. 9/15/81 and 11/25/81)
The heap, ponds, and plant covered an area of 14.2 acres. The 5.2 acre heap (225,400 square feet)
had an "impervious soil pad" (no further description of the liner system was available). Barren
solution with an "alkaline pH" and a sodium cyanide concentration of 0.05 percent was pumped from
a barren pond and applied to the heap with a "pump and spray line system" (actual pH and
application rates were not provided, nor was pond construction described). Pregnant solution drained
(whether through drain pipes or directly on the soil pad was not described) to a "plastic lined launder"
in the front of the pad, thence through "launder channels" to a Hypalon-lined pregnant pond. There
4-48
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Site Visit Report: Nerco Minerals Cripple Creek
also was an emergency overflow pond, but no details on construction were provided. Total capacity
of all ponds was 807,840 gallons, sufficient to contain precipitation from the 100-year/24-hour storm
event as well as at least 24 hours of heap drainage. Berms outside the ditch (i.e., outside the
"launder") kept solution flow in the ditch. The heap was actively leached for six months a year;
during winter, solutions were held in the ponds. Unspecified metallurgical difficulties in the
"leaching plant" (otherwise undescribed) in late 1976 caused a cessation of operations until 1978.
The amount of waste rock used as ore hi 1976 was not determined; in 1978, about 12,000 tons were
added to the heap and hi 1981, another 100,000 tons were added. (Newport Minerals 9/14/81)
The quantity of ore added to the heap after 1981 was not described hi available documentation.
However, cyanide leaching apparently ended sometime hi 1985 (Dayspring Mining Corporation
10/28/88).
%
Reclamation plans included rough-grading of the heap. The heap was to be rinsed with fresh water
and, if cyanide were still detected, a "suitable oxidant" was to be added to the rinse. (Newport
Minerals 9/14/81) When cyanide was no longer detected, the ponds were to be backfilled. The
backfilled ponds and other disturbed areas were to be revegetated, but not the heap itself (MLRD
5/22/86).
Through the 1980s, the ponds were sampled at various tunes. Available monitoring data for the '76
site ponds are presented hi Table 4-6. The current status of the '76 project was not determined
during the site visit.
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-6. Concentrations of Selected Parameters in '76 Project Barren and
Pregnant Solution Ponds
(milligrams per liter, unless otherwise indicated)
Parameter
6/17/86*
9/14/88"
Barren Pond
pH (s.u.)
Total CN
FreeCN
Silver
Zinc
NR
NR
NR
NR
NR
8.3.
0.056
0.030
< 0.005
< 0.005
Pregnant Pond
pH (s.u.)
Total CN
FreeCN
Weak-acid-
dissociable CN
Silver
Zinc
NR
8.09
2.11 '
2.79
NR
NR
9.1
0.056
0.29
NR
0.030
0.006
NR Not reported
Sources:
a Newport Minerals 7/3/86
b Accu-Labs Research 10/7/88.
4-50
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Sire Visit Report: Nerco Minerals Cripple Creek
4.5 REGULATORY REQUIREMENTS AND COMPLIANCE
A number of State agencies are responsible for regulating various aspects of Nerco Minerals
Company's Cripple Creek operations. These agencies and the permits they have issued to Nerco are
described in sections 4.4.1 through 4.4.4 below.
4.5.1 Colorado Mined Land Reclamation Division
The agency with by far the most extensive involvement with the Ironclad/Globe Hill facility and
Nerco's other Cripple Creek operations has been the Mined Land Reclamation Division (MLRD) in
the Colorado Department of Natural Resources. MLRD is responsible for implementing the Mined
Land Reclamation Act. MLRD reviews permit applications, inspects sites, and makes
recommendations to the Mined Land Reclamation Board on permitting and enforcement actions. The
Board issues rules and regulations under the Act; approves and issues permits, including bonding
requirements; issues Notices of Violations and Cease and Desist Orders; and imposes civil and
criminal penalties on operators that violate permits or Colorado statutes and rules.
Permits are issued under sections 110 and 112 of the Act. Regular Operations Permits, or "112
Permits" are required of operations that affect 10 or more acres or that extract more than 70,000 tons
of material per year. Limited Impact Operations Permits, or "110 Permits," are required of facilities
that will affect less acreage and extract less material than the 112 cutoffs.
A permit application is required prior to facility construction and operation. The application must
describe the surrounding area and proposed construction in some detail, and must describe planned
facility operations and reclamation. The right to conduct the mining operations must be demonstrated
(e.g., through leases, proof of title, etc.), and mineral and surface owners of land in the proposed
permit area and adjacent areas must be identified.
Following receipt of a permit application, MLRD notifies the Colorado Department of Health
(agencies of which administer the water and air programs of the State), the Division of Water
Resources in the Office of the State Engineer (which is responsible for water rights), and other State
and local agencies. The various agencies may then provide comments and recommendations on the
application. In the case of Teller County (and possibly other counties as well), the County and/or
towns must find that the proposed operation is consistent with local requirements, including zoning.
Applicants also place advertisements in local newspapers to inform the public that an application has
been received and to indicate that records can be reviewed in MLRD offices. MLRD staff review the
application and notify the applicant when additional information is necessary. Finally, MLRD
inspects the site and recommends approval, conditional approval, or disapproval to the Board. The
Board considers applications in open meetings. Upon approval, the Board issues the permit, which
incorporates by reference the application, as well as any correspondence and technical reports that
describe the permitted activities/facilities.
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Site Visit Report: Nerco Minerals Cripple Creek
To add additional acreage to a permitted area, a permittee must apply for an Amendment to the
permit. For changes that do not add additional areas (e.g., operational or other changes within the
permit area), operators must apply for Technical Revisions to the permit. The review and approval
process for Amendments and Technical Revisions is the same as described for original applications,
except that Technical Revisions may not require public notice. There is no single "permit" that
incorporates all the requirements applicable to an operator, as there is, for example, for NPDES
permits (see section 4.4.2 below). Rather, the requirements are in approved applications for permits,
Amendments, and Technical Revisions, in related MLRD and operator correspondence, and in
technical studies and reports that are used to support applications.
When MLRD inspectors identify possible violations of permit conditions or Colorado regulations,
they recommend specific remedies to the operator, who receives a copy of the inspection report.
When potential violations are serious or are not remedied within time frames specified by the
inspector, MLRD recommends appropriate actions to the Board. Such actions can include warnings,
Notices of Violation, Cease and Desist Orders, permit revocation, and bond forfeiture. The Board
also can impose civil penalties up to $1,000 per day per violation; actual penalties are based on a
sliding scale based on seriousness and the operator's intent (e.g., inadvertent versus negligent versus
willful); again, recommendations on penalties are made to the Board by MLRD.
MLRD typically inspects facilities at least annually, although more frequent inspections are conducted
if conditions warrant. During the extended period when the Globe Hill and Victor Mine permits were
not active (from 1986 through 1991), for example, MLRD conducted a number of inspections.
MLRD also inspects facilities prior to Board consideration of applications or enforcement actions.
Table 4-7 shows MLRD permits issued to Nerco (and/or its subsidiaries and operating companies).
As noted previously, the area affected by Nerco's Ironclad/Globe Hill project was formerly two
separate permitted operations with two separate operators: the Globe Hill project under permit 77-
367 and the Victor Mine under 81-134. The areas have now been consolidated by Nerco into a single
project, with some facilities extending over both permit areas (e.g., the Ironclad heap leach pad) and
some facilities used in common (e.g., the crusher, the waste rock dump, and the Victor Mill).
At the time of the site visit, the Victor site was held solely by Nerco, while the Globe Hill site was j
joint venture between Nerco subsidiary Pikes Peak Mining Company and Golden Cycle Gold
Corporation. According to Nerco, the Victor operation has since been added to the joint venture
Nerco's other Cripple Creek operations are generally permitted separately, as shown in Table 4-7
As can be seen, individual waste rock dumps that Nerco (or predecessor operators) proposed to
remove and leach on the Victory or Carlton Mill pads are often permitted separately. MLRD and
Nerco indicated that at least some of the 110 permits for waste rock dumps were in the process >
being consolidated into a single permit.
4-52
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Site.Visit Report: Nerco Minerals Cripple Creek
Table 4-7. Colorado Mined Land Reclamation Division Permits Issued to Nerco"
Permit
Type
Permit
Number4
Project Name
Project Description
112
M-77-367
Globe Hill
See text and Table 4-3. Globe Hill open pit mine, waste rock dump,
three inactive heap leach pads, and portion of new Ironclad heap.
112
M-81-134
Victor Mine
See text and Table 4-2. Ironclad open pit mine, waste rock dump, most
of new Ironclad heap, and gold recovery facility (through smelting).
Formerly included vat leaching and tailings disposal.
112
M-80-244
Carlton Mill Project
(Pads 1. and 2)
See section 3.6.1 and Appendix A. Previously, mill and carbon- in-
leach facility, gold recovery facility (through smelting). Since.mid-
1980s, heap leach and CIC circuit, with old mine dumps serving as
sources of ore. Pad 2 still operational.
112
M-86-024
Victory Project
(Portland Pit, Pads 3
and 4)
See section 3.6.2 and Appendix B. Open pit, waste rock dump, two
heap leach pads, and formerly portable carbon columns. Pit under
reclamation, heaps to be 'decommissioned" in 1992.
112
M-86-009
Lillie Project
Permitted as heap leach of many old waste dumps. Heap leach not
constructed but dumps stripped for use as ore on Victory Project and
Carlton Mill heaps (CC&V 3/31/86).
Originally, 241.33 acres permitted for following dumps: Joe
Dandy, Last Dollar, Portland #2, Golden Cycle/Teresa, Lillie,
Ajax, Upper Independence, Lower Independence, Portland #3,
Victor, Deadwood, South Burns, Empire, Isabella, Wildhorse, and
Morning Glory dumps. Total of 1,556,000 tons of rock.
Over the course of the permit, some areas were removed from this
permit and placed under Gold Star and Victory permits.
112
M-88-064
Gold Star Pit
119.61 acres, open pit mine on Bull Hill to provide ore for Pad 4.
Permitted at 1,100 feet east-west x 900 north-south x unspecified
depth.
In application, estimated 625,000 to 1,500,000 tons of ore,
2,400,000 to 3,000,000 tons of waste rock. Rock dump on nearby
saddle, possibly to use some rock to replace other area dumps
removed for leaching.
$32,600 bond proposed.
Inactive since August 1989 but drilling was to continue in 1992.
(MLRD 10/26/88)
112
M-91-134
Cameron and School
Section heap leach
pads
Reclamation-only permit. Originally, these were Newport Minerals
operations (permits 82-16 and 81-98). Following Newport's bankrupuv
in 1985, ML'RD revoked the bond and confiscated Newport's assets.
including these heap leach pads. Under this permit, Nerco (CC&Vi ix
to remove 600,000 - 700,000 tons of ore from heaps and transport in
Ironclad heap for releaching. Not clear if Nerco or MLRD is
responsible for final site reclamation (permit application indicates
MLRD would be responsible, but undated "Reclamation Plan for
Cameron and School Section Heap Leach Pads" indicates CC&V u,.uid
reclaim the site.) (MLRD 3/4/92)
A major spill occurred on the site in 1984, when 150,000 - 200.
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Site Visit Report; Nerco Minerals Cripple Creek
Table 4-7. Colorado Mined Land Reclamation Division Permits Issued to Nerco (continued)
Permit
Type
Permit
Number1*
Project Name
V
Project Description
Mine Dumps Permitted for Removal of Rock for Leaching
110
110
110
110
110
110
110
110
110
110
110
110
110
110
110
M-82-214
M-88-025
M-88-026
M-88-096
M-88-097
M-88-098
M-88-099
M-88-100
M-89-059
M-89-060
M-89-061
Mr90-109
M-90-110
M-90-111
M-91-114
Lower Mary '
McKinney Dump
Anchoria Leland
Dump
Chicago Tunnel
Ocean Wave Mine
Dump
Tornado/Raven
Dump
Blue Flag Mine
Dump
Howard Mine Dump
Index Mine Dump
Rigi Mine Dump
Upper Mary
McKinney Mine
Dump
Hull City and
Sacramento Mine
Dumps .
Bertha B and Maggie
Dumps
Midget Mine Dump
Moon Anchor Dump
Clyde/Modoc Dump
7 acres: originally mined for decorative rock by Pioneer Sand
Company, permit transferred to CC&V in 1986. (MLRD 4/18/83)
8.5 acres, 100,000 tons to Pads 2 and 4 beginning in 1988-1989
(MLRD 5/16/88a)
5.16 acres. Chicago Tunnel to be used to gain access to Proper Mine
(underground) for mining of undetermined amount of ore, to be
removed to Pad 2. (MLRD 5/l6/88b)
9.8 acres, 40,000 tons to Pad 4 beginning in 1988-1989. (MLRD
ll/28/88a)
7.3 acres, 50,000 to 70,000 tons to Pad 4 beginning in 1988-1989.
(MLRD ll/28/88b)
9.7 acres, 40,000 tons to Pad 4 beginning 1988-1989. (MLRD
11/28/88C)
9.9 acres, 55,000 tons to Pad 2 or 4 beginning in 1988-1989. (MLRD
ll/28/88d)
9.9 acres, 95,000 tons (< 70,000 tons per year) to Pad 2 beginning in
1988-1989. (MLRD 12/9/88)
6.0 acres, 5,000 tons to Pad 4 beginning in 1989. (MLRD 7/14/89)
8.9 acres: 60,000 tons to Pad 2 beginning in 1989-1990. Required
studies, stabilization, and retention of existing cribbing supporting
dump. Permit issued following NOV for mining without a permit
(removal began after application but before issuance). (MLRD
7/27/89a)
9.9 acres, 18,000 tons to Pad 4 beginning in 1989. Permit issued
following NOV for mining without a permit (removal began after
application but before issuance). (MLRD 7/27/89b)
5.0 acres, 27,000 tons to Pad 2 or 4 beginning in 1990-1991. (MLRD
10/2/90a)
5.0 acres, 57,000 tons to Pad 2 beginning in 1990-1991 (MLRD
10/2/90b)
9.0 acres, 70,000 tons to Pad 2 beginning in 1990-1992. (MLRD
10/2/90c)
10 acres, unspecified tonnage ( < 70,000 tons per year) to Pad 2 in
1991-1992. (MLRD 11/7/91)
NOTES:
a Most permits are actually issued to Cripple Creek and Victor Gold Mining Company, although some are issued to Nerco
or Pikes Peak Mining Company.
b The first number in the permit number reflects the year in which the original permit was issued.
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Site Visit Report: Nerco Minerals Cripple Creek
Reclamation of each of Nerco's Cripple Creek sites is guaranteed by a bond, which is in the form of
a surety by St. Paul Fire and Marine Insurance Company in the favor of Nerco (or Pacificorp). The
total surety is for $1,000,000, with stipulations for individual bonds for individual sites. Bonds are
based on the operators' and MLRD's estimate to reclaim the site in accordance with the Mined Land
Reclamation Act and local requirements. During the site visit, MLRD indicated that bonds
established prior to 1991 would be re-examined and re-calculated in the near future. The total
amount of bonding required of Nerco for its various operations was not determined. Reclamation
bonds ranged from $1,000 for some of the areas where waste rock was removed for leaching to
$391,948 for the Ironclad/Victor permit area.
*
For Nerco's Ironclad/Globe Hill project and the other Cripple Creek operations, MLRD operational
and performance requirements are found throughout the many applications (for the original permits
and for numerous Amendments and Technical Revisions) and the extensive correspondence for each
permit area (i.e., permits 77-367 and 81-134 in the case of Ironclad/Globe Hill). Table 4-8 presents a
permit history of MLRD permit 81-134, originally issued to Silver State Mining Corporation for the
Victor Mine and assumed by Nerco in 1984. Table 4-9 presents a similar history of permit 77-367,
originally issued to Newport Minerals in 1977 for the Globe Hill project and subsequently assumed by
Dayspring Mining Corporation in 1986 and Nerco (actually, Pikes Peak Mining Company) in 1991.
The tables show the dates when applications (for the permits, amendments, and technical revisions)
were submitted or approved, identify the permittee at the time, and describe the permitted operations.
The tables are based on materials in MLRD permit files, as cited in the table. Similar tables for the
Carlton Mill and Victory Projects are presented in Appendices A and B, respectively.
4.5.2 Colorado Department of Health, Water Quality Control Division
The Water Quality Control Division in the Colorado Department of Health is authorized to implement
the National Pollutant Discharge Elimination System (NPDES) in Colorado by means of the Colorado
Discharge Permit System (CDPS). The State has not issued CDPS permits to Nerco's MLRD-
permitted operations since they are designed not to discharge to surface waters (except storm water
from some areas and some sites). However, the State has issued CDPS permit CO-0024562 to the
Cripple Creek and Victor Gold Mining Company for discharges from the Carlton Tunnel to Fourmile
Creek. The permit was reissued on March 12, 1992, and is effective from May 1, 1992 through
March 31, 1997.
Mine water proved to be a problem throughout the history of the Cripple Creek mining district. The
Carlton Tunnel was completed in 1941 and drains hundreds of miles of underground workings in the
district. It extends six miles from the Cripple Creek area to Fourmile Creek, a tributary of the
Arkansas River. In the mining district, the tunnel is at an elevation of about 7,000 feet above sea
level, or 2,000 to 3,000 feet below the surface. At its discharge end, the elevation is about 6,700
feet.
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-8. Permit History of the Victor Mine (MLRD Permit 81-134)
Permit 81-134: Victor Mine
Date
March 25, 1981
to September 8,
1981
(Silver State
Mining
Corporation
3/25/81; MLRD
9/8/81)
December 1983
(Silver State
12/7/83)
March 1983
through June
1984
(Silver State
5/26/83, MLRD
5/30/84)
June 1984
MLRD,
(6/20/84)
Event
Permit
application
Technical
Revision 1
Amendment
1
Change in
operator
Permittee
Silver State Mining
Corporation
Lessor (surface and
mineral): Gaston
Coblentz and
Cherry M.
Lawrence
Silver State Mining
Corporation
Silver State Mining
Corporation
Nerco Minerals
Company
Description
7.4 acre 5-year, mine, including:
1.8 acre open pit (Ironclad mine), partly in
previously mined pit. Final size to be 225 x 350
feet x 100-150 feet deep. 15-foot wide benches at
30 foot intervals (height). .
Plastic lined 4.43 acre tailings area with 15-20
foot dam downslope to impound tailings water.
0.15 acre crushing plant, 0.05 acres for field
conveyors, 0.93 acres for processing plant (no
further descriptions)
Reclamation: generally, leave as "mining area."
Fence entire pit perimeter, grade tailings dump to
2H:1V or less, resoil/reseed impoundment dam
and benches; grade and revegetate other areas.
Described in MLRD notes only (correspondence
not obtained): closed vat cyanide system in 200 x
200 building. 9.5 inch concrete rebar
construction, with rubber waterstops in joints. 4
vats, 3-day cycle; double-rinse tailings, conveyor
to tailings. Ore drained for at least two hours
before 4-6 hour unloading process.
No waste rock, No water diversion needed (no
upsiope area).
$7,000 bond proposed; actual amount required not
determined.
Add vehicle maintenance building, enlarge another
building and parking lot, all on existing permit area.
Increase sizes of pit, waste rock dumps, and tailings.
Added tailings area 2 across Range View Road.
Also included tailings reclamation plan: establish
test plots to allow development of final
revegetation/reclamation plan. New permit area was
54.2 acres. Bond increased by $36,400 to $127,896.
4-56
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-8. Permit History of the Victor Mine (MLRD Permit 81-134) (continued)
Permit 81-134: Victor Mine
Date
Event
Permittee
Description
June 1984 to
October 1984
(Nerco 6/19/84,
MLRD
10/17/84, 3/21-
22/85, and
1/2/86)
Amendment
2
Nerco Minerals
Company
Expansion of facilities and operations:
Regrade and deactivate tailings area 2, extend
tailings area 1 to north, with perimeter berms and
20-mil PVC liner. Reclamation plan for tailings:
regrade to 2H:1V and re vegetate. Establish test
plots to assess revegetation options.
Build two new collection ponds in addition to four
existing ponds.
Sample tailings collection ponds monthly for pH,
free CN; sample annually for full suite of
parameters.
Re-locate Range View Road to east.
Deactivate old and establish new waste rock
dump.
Increase water usage five-fold to 100 gpm.
Increase mining rate to 3,000 tpd.
Increase bonding to $373,948.
Apparently added four 2,000 ton vats (Nerco
2/12/86 refers to this addition).
August 1984
(Nerco 8/22/84)
Technical
Revision 2
Nerco Minerals
Company
Replace 3.2 acres of undisturbed lands with 3.2
acres to be used for haul road from pit to dump.
(Presumed approved; no correspondence obtained.)
March 1, 1985
(MLRD 3/1/85)
Technical
Revision 3
Nerco Minerals
Company
Exchange 11.2 undisturbed areas designated for
waste dump with another 11.2 acres, where dump
was actually proposed to be located.
1985
(MLRD 7/1/85)
Amendment
Nerco Minerals
Company
7-acre tailings area on adjacent Globe Hill project
(the old Globe Hill heap) removed from Newport
Minerals permit 77-367, to be added to permit 81-
134. Nerco also was to assume responsibility for
Globe Hill heap leach pregnant pond.
(Documentation on actual addition of the area to
permit 81-134 not obtained.)
January 24,
1986
(Nerco 1/24/86;
MLRD 1/28/86)
Notice of
Temporary
Cessation
Nerco Minerals
Company
Cease operations for at least 180 days. During
hiatus:
Transfer solution in tailings disposal area to
empty vats as necessary to maintain capacity far
100-year/24-hour storm event. .
Stabilize and seed topsoil stockpiles.
Divert run-on from undisturbed areas.
Continue monitoring integrity of facilities and
monthly /annual sampling of collection ponds.
Cessation lasted until 1990.
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-8. Permit History of the Victor Mine (MLRD Permit 81-134) (continued)
Pennit 81-134: Victor Mine
Date
Event
Permittee
Description
March 25, 1986
(Nerco 2/12/86,
3/20&24/86;
MLRD 1/2/86,
2/20/86,
3/25/86)
Technical
Revision 4
Nerco Minerals
Company
Site in cessation status. Revisions to tailings
disposal system in response to November 6, 1985,
tailings slough. Some were previously approved in
Amendment 2:
Change pile foundation preparation, reduce
planned height to 150 feet.
Avoid steep slopes as tailings liner advances
Relocate county road 84 to allow room for 500-
foot-wide front for tailings advance.
Reduce working face slope to 2:1.
Relocate tailings collection ponds to permanent
location: one to be constructed immediately, one
on resumption of production.
Convey drainage/run-off from pile to pond in 18-
inch pipe laid in Hypalon-lined ditch.
February 26,
1987
(MLRD
2/26/87; Nerco
1/6/87)
Technical
Revision 5
Nerco Minerals
Company
Site in cessation status. Change in method of
transfer of run-off/seepage from tailings area to
collection pond. Formerly, 18-inch plastic pipe in
20-mil PVC-lined ditch. Pipe failed due to faulty
resin. Changed to: from tailings ditches directly
into open double-lined bermed ditch (36-mil Hypalon
liner over geotextile over existing 20-mil PVC liner);
drain into 18-inch pipe enclosed in underliner to pass
through berm around pond. Inside berm, discharge
end of pipe to rest on top of lined portion of pond.
October 17,
1990
(Nerco 9/17/90;
MLRD
10/29/90)
Reactivation
of Victor
Mine
Nerco Minerals
Company
End cessation that began in late 1985. Planned work
included expansion of tailings pile to north (as
planned in TR 4):
Site preparation within approved tailings pile area
Laying upgraded liner material (described only as
"upgrade from the approved PVC liner")
May 10, 1991
(Nerco 5/10/91)
Amendment
1
Nerco Minerals
Company
Three-phased construction in 1991 and 1992:
New 1,500,000 square foot double-lined
"Ironclad".heap leach pad, partially built where
Globe Hill (Phase HI) and Forest Queen (Phase
II) heap leach pads were located. See section 3.5
for construction details.
Globe Hill and Forest Queen pads to be
"detoxified" (not described further).
Move 90,000 tons of existing tailings pile for pit
expansion (relocation site not specified).
Existing tailings pile to be graded to 2H:1V with
20- to 25-foot benches. Formulate plans to load
benches with growth medium and establish
vegetation.
At closure, construct six-foot fence around
Ironclad pit.
Reclamation of new pad not described.
Add 12 or 20 acres to permit (application cited
both figures) for a total of 217.1 acres.
Total reclamation costs and bonding: $391,948
($18.000 from additions, $373,948 already
existing).
4-58
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-9. Permit History of the Globe Hill Project (MLRD Permit 77-367)
Permit 77-3
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-9. Permit History of the Globe Hill Project (MLRD Permit 77-367) (continued)
Permit 77-367; Globe Hill Project
Date
Event
Permittee
Description
September 1981
(Geddes,
MacDougall,
Geddes &
Paxton
11/25/81;
MLRD
12/21/81)
Technical
Revision (1?)
(associated
with
Amendment
2)
Newport Minerals,
Inc.
[Application not obtained; technical revision
described in references cited,] Existing Forest Queen
and 2A pads added to permitted operations within
permit area (previously cited for operating heaps
without describing in approved application). Pads
are located on surface of waste rock dump (MLRD
7/1/85).
September 14,
1981
(Newport
Minerals
9/14/81)
Amendment
2
Newport Minerals,
Inc.
Added '76 site, about 14.2 acres, to existing permit.
About 1 to 1.5 miles SW of original permit area, on
ridge between two dry gulches.
225,400 square foot (5.2 acres) heap leach pad
and ponds; originally constructed in 1976, with
waste rock from area dumps used as ore.
Experienced metallurgical difficulties in "plant" in
late 1976, shut down until 1978. In 1978, 12,000
tons added to top of heap; another 100,000 tons
added in 1981. Orpha May, Logan, Blue Bird,
Dexter, Specimen, and American Eagle dumps
served as ore. Heap constructed in 20 foot lifts.
Pond capacity 807,840 gallons (> 100-year/24-
hour storm event).
Used 0.05 percent NaCN solution. "Prepared
pad" of "impervious design" (no other
description). "Plastic lined" "launder channels"
convey solution to plastic lined collection ponds.
Seasonal operation, with solutions held in ponds
over winter.
Also an emergency catch basin downhill of ponds
for overflow. Relined by Newport.
'76 site to be fenced.
(Site had been mine dumps prior to 1976). Newport
"relined" the pond and fenced the area; they also
agreed, when leaching was complete, to measure
effluents until quality approximated nearby streams.
The amendment brought the total permitted acreage
to 53.2 acres. Additional bonding (if any) was not
determined.
March 26, 1982
(MLRD
3/26/82)
Amendment
3
Newport Minerals,
Inc.
Incorporated 6.8 acres (for new total of 60 acres) of
five old mine dumps on west of Globe Hill into
permit. Dumps to be used as source of ore for one
or more heap leach pads. Dumps included:
Colorado King, Proper, Geneva, Chicago and
Cripple Creek Tunnel, Abe Lincoln. Increased
bonding by $8,500 (total not determined).
4-60
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-9. Pennit History of the Globe Hill Project (MLRD Pennit 77-367) (continued)
Permit 77-367: Globe Hill Project
Date
September 1982
(MLRD
9/27/82)
May 1984
MLRD (5/30/84'
and 7/1/85)
September 28,
1984
(MLRD
9/28/84)
Event
Technical
revision (2?)
Amendment
4
Technical
Revision 4
Permittee
Newport Minerals,
Inc.
Newport Minerals,
Inc.
Newport Minerals,
Inc.
Description
Added 0.68 acre of new heap to SE comer of
existing '76 pad and enlarged pond. No change hi
acreage or bond. (Described hi MLRD 7/1/85)
Added to permit: -7 or 8 acre storage area for
tailings from contiguous Silver State Mining
Company (permit 81-134) vat leach operation ("short
term solution to Silver State's waste disposal
problems").
6.4 acre area to be lined with 20-mil PVC, sealed
with Silver State liner at boundary (on south).
About 662,000 tons of tailings, 100 feet high at
highest point. 1,500 tpd for six months (June -
November 1984), 3,000 tpd through June 1985,
when full capacity reached. Surrounded on N, E,
and W by 12-foot buffer ditch and 8-foot berm.
Solution collection pond (210 x 100 x 4 feet, 1.65
acre-feet) at NE corner, with drainage ditch from
surrounding berm. 4-inch pipes in tailings to
drain to pond. To contain 100-year/24-hour
storm event. Leachate/run-off to be pumped to
Victor mill.
12,500 cubic yards of topsoil stored on W corner
(on liner).
Final contours: Benches at 30-foot intervals,
2H:1V slope.
Including access roads, total acreage after
amendment: 68.12 acres (or 67, according to
Amendment 5).
Additional financial warranty: $17,500.
This entire area removed from this permit in 1985
and added to Nerco permit 81-134. See
amendment 5 below.
On-site disposal of triple-rinsed and crushed
"disused" cyanide containers hi area of waste rock
'dump. To be covered with 12 inches soil/clay, then
rock. Change followed inspection orders.
4-61
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-9. Permit History of the Globe Hill Project (MLRD Permit 77-367) (continued)
Permit 77-3OT: Globe Hill Project
Date
July 1, 1985
(MLRD 7/1/85)
May -
September 1986
(MLRD 6/3/86,
7/1/86, 9/4/86,
9/29/86)
September 25,
1986 (MLRD
9/25/86)
September -
November 1988
(MLRD 9/13/88,
9/22/88a,
11/15/88,
1/23/91)
February 6,
1991 (MLRD
2/6/91)
Event
Amendment
5 (and
additional
permit
conditions)
NOVs and
Cease and
Desist Order
Change of
operator
NOV M-88-
013 and
Cease and
Desist Order
Change in
operator
Permittee
Newport Minerals,
Inc.
Newport Minerals,
Inc.
Dayspring Mining
Corporation
Dayspring Mining
Corporation
Pikes Peak Mining
Company
Description
Deepen and enlarge pit: increase approved area
4.5 acres to 8.5 acres, depth from 125 to 300
feet. Not known if implemented.
Add 13 acres to waste rock dump, for total of 27
acres. Not known if implemented.
Construct and operate new vat leach and tailings
disposal operation similar to adjacent Nerco
operation. Never implemented.
Change from nonreusable barrels for cyanide and
caustic to reusable containers. Not known if
implemented.
Remove the 7-acre storage area (including Globe
Hill heap) for Permit 81-134 tailings authorized
by amendment 4 (see above) from this permit and
convey to Nerco. (Reilly 4/6/86, MLRD
5/22/86).
Financial warranty increased from $25,00 to
$90,000. Never posted since most construction
not implemented.
Over five year period, four waste dumps about
0.75 miles SSE of plant (the Logan, American
Eagle, and Lucky Gus 1 and 2 dumps), to be
removed and sold as decorative rock. At least
partially accomplished.
Globe Hill (Forest Queen) violations, described in
text. Delay in corrective action led to $109,800
civil penalty. Culminated in Dayspring Mining
Corporation succeeding Newport Minerals as
operator.
'76 site violations, described hi text. Led to civil
penalty of $2,600. Finally resolved in 1991 upon
succession of Cripple Creek and Victor Gold Mining
Company as operator, with Pikes Peak Mining
Company as manager.
Included $25,000 bond (by St. Paul Fire & Marine-
Insurance Co. of Minnesota, coverage from
11/13/90 through 11/13/93.
4-62
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-9. Permit History of the Globe Hill Project (MLRD Permit 77-367) (continued)
Permit 77-367; Globe Hill Project
Date
October 10,
1991
(Nerco 5/10/91,
MLRD
10/10/91)
Event
Technical
Revision 4
(and
unnumbered
revision to
Permit 81-
134)
[This was
the second
revision #4.]
Permittee
Pikes Peak Mining
Company
Description
Detoxify and grade Forest Queen pad to northeast.
Where heap pad is located, install pan of new
Ironclad pad and collection ditches. Solution to
drain to pregnant pond 4A on adjacent Victor Mine
permit. Part of phased construction under permit
81-134, described in sections 4.2.2 and 4.3.5.
Ultimately, this pad to be joined to other components
of Ironclad heap leach pad.
Summary
Reclamation requirements for entire site (MLRD 5/22/86):
Pit: rough-grade, leave warning bench and access/exit ramp, fence area, no
revegetation.
'76 and Forest Queen/2A heap: rough-grade, rinse until no detectable cyanide, no
revegetation.
Ponds: Monitor for one year or more: when fluids are similar to Cripple Creek or
Wilson Creek, backfill ponds and re vegetate.
Waste rock dump: rough-graded, with dome-like upper surface (to eliminate
ponding/infiltration); maximum slope 1.5H:1V, no revegetation.
Other areas: grade to slopes less than 3H:IV, mulch and revegetate. Remove buildings
and equipment.
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Site Visit Report: Nerco Minerals Cripple Creek
Flow from the Carlton Tunnel can be discharged directly to Fourmile Creek (discharge point 001) or
can be routed through a series of four settling ponds prior to discharge (discharge point 002). The
CDPS permit places the same effluent limits on both discharge points. The CDPS permit includes
limits on flow and on conventional and toxic pollutants; it also requires whole effluent toxicity testing.
Effluent limits from the previous and the new permits are show in Table 4-10. Also presented in
Table 4-10 are the results of 1991 effluent monitoring. In 1991, discharges to Fourmile Creek
averaged over 2,000,000. gallons per day, and all discharges during the year were from the settling
ponds.
The new permit limits are conditional on no mining occurring in the Carlton Tunnel; if there is
mining activity in the tunnel or at a level underground that requires active pumping of water out of
the Carlton Tunnel, alternate limits (not presented in Table 4-10 since no underground mining is
occurring or planned) would apply. The permit requires that acute whole effluent toxicity (WET) be
monitored quarterly, chronic WET semiannually, and other parameters twice monthly.
4.5.3 Colorado State Engineer, Division of Water Resources
The Division of Water Resources (DWR) in the Office of the State Engineer is responsible for water
rights issues in the State. MLRD routinely informs DWR of pending permit applications and
amendments. On July 30, 1991, after reviewing Nerco's application to amend permit 81-134 (to add
the Ironclad heap leach pad, including solution ponds), DWR recommended against approval of the
amendment. According to DWR, Nerco "cannot legally store or use precipitation run-off [in the
solution ponds described in section 4.3.5] without a Water Court decree, or a substitute water supply,
plan approved by this office [i.e., DWR] unless all decreed water rights in the Arkansas River basin
downstream of this location are fully satisfied." DWR records showed no existing decreed water
rights and no substitute water supply plan, so DWR recommended against approval of the
amendment. (Colorado Office of the State Engineer, 7/30/91) Notwithstanding this recommendation,
MLRD approved the amendment after being assured by Nerco that the company would immediately
apply'for a substitute water supply plan. According to Nerco during the site visit, this process is still
underway. It is not clear why the State Engineer took exception to this particular amendment and
these particular ponds: previous ponds on this site and other sites have long been used to collect run-
off, and there is no indication that DWR had taken exception to any previous permitting action, for
this or any other of Nerco's operations.
4.5.4 Other Permits
A number of other permits have been issued for various Nerco operations (permits may have been
issued to Cripple Creek and Victor Gold Mining Company, Pikes Peak Mining Company, or Nerco-
this was not determined). These are shown in Table 4-11. As noted in chapter 4.2, a contractor
operates the crusher and conveyor system at the Ironclad/Globe Hill site and is permitted separately
EPA did not obtain and examine the permits listed in Table 4-11 or those issued to Nerco contractors
4-64
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-10. Discharge Limitations and Monitoring Data for Carlton Tunnel
(units are milligrams per liter except as noted)
Effluent
Parameter
Flow (MOD)
pH (s.u.)
Total
Suspended Solids
Silver
Zinc
Lead
Copper
Cadmium
Mercury
Acute WET",'
Chronic WET
Effluent Limits Effective
May 1992*
30-Day
Average
2.58
Daily
Maximum
N/A '
6.5 - 9.0
30
0.0008
0.130
0.03
0.059
N/A
0.0212
1.00
0.920
0.098
N/A
N/A
N/A
50 %/
IWC=37%
Report
Effluent Limits
1986 - 1992"
30-Day
Average
2.57
Daily
Maximum
N/A
6.5-9.0
30
0.0001
0.14
0.08
0.04
0.007
0.0001
45
0.0002
0.28
0.16
0.08
0.014
0.0002
N/A
N/A
Concentrations Reported
January - December 1991'
Minimum - Maximum
1.87-2.40
7.8-8.1
< 5.0 - 14
< 0.0001 - < 0.0002
0.006-0.13
< 0.005
< 0.005
< 0.005
< 0.0001
N/A
N/A
NOTES:
N/A Not applicable
a These effluent limits are effective May 1992. Limits for silver, zinc, lead, and copper are on "potentially dissolved" metals. Twice-
monthly sampling is required for all parameters except WET, which is tested quarterly (for acute) or semi-annually (for chronic).
b These effluent limits were effective prior to May 1992 (and were applicable during the period covered by the monitoring data presented
in the table). Limits and monitoring results are on 'potentially recoverable" metals except mercury, which is on "total" mercury. All
parameters were required to be sampled monthly.
c Although there are limits on 30-day average and maximum daily concentrations, monthly averages generally were based on single samples.
whose results were reported both as averages and daily maxima. Thus, the ranges presented are simply the maximum and minimum
concentrations reported during the year.
d WET: Whole Effluent Toxicity limits added in 1992 revision. Acute 48-hour tests are to use Ceriodaphnia sp. and acute 96-hour tests
are to use fathead minnows. Chronic tests also are to use these species the First year, after which CC&V may petition for one-species
testing.
e Through March 31, 1995, there are reporting requirements only. Acute toxicity limits will begin April 1, 1995. Limits: no acute toxiciry
in effluent from discharge point. Limit will be considered exceeded if species mortality in any dilution (including 100 percent effluent)
exceeds 50 percent; or if mere is a statistically significant difference in mortality (at 95 percent confidence level) between control and any
dilution less than or equal to an Instream Waste Concentration (IWC) of 37 percent.
Sources: Colorado Department of Health, Water Quality Control Division CDPS permit CO-0024562 (3/12/92) for limits effective Ma>
1992; Monthly Discharge Monitoring Reports for 1991. submitted to Colorado Water Quality Control Division, for poor limns
and 1991 monitoring data.
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Site Visit Report: Nerco Minerals Cripple Creek
Table 4-11. Other Permits Issued to Nerco Minerals for Cripple Creek Operations
Permit number
Type permit
Operations covered
Colorado Department of Health
83TE351
88TE241
87TE301F
C-13, 269-1-5,
C-7
Air emissions
Fugitive air
emissions
Fugitive air
emissions
Not determined
Not determined.
Clyde/Modoc mine dump crushing
removal
and rock
Portland Pit: operations covered not determined
Ajax (Lillie project?)
Carlton Mill
Colorado Division of Mines
Not determined
Magazine permit
Not determined
Source: Provided by Nerco during site visit.
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Site Visit Report: Nerco Minerals Cripple Creek
4.6 ANNOTATED LIST OF REFERENCES
Accu-Labs Research, Inc. 1988 (October 7). Letter from M. Fabisiak, Water Laboratory
Supervisor, to B. Mountford, Dayspring Mining Corporation. Sample results from sampling of
'76 Project Ponds.
Cripple Creek and Victor Gold Mining Company. 1985 (March 12). Amendment to Mined Land
Reclamation Permit 80-244. Application for permit amendment (Carlton Mill project: add heap
leach Pad 1 and ponds.)
Cripple Creek and Victor Gold Mining Company. 1986 (January 16). Amendment No. 2 to Mined
Land Reclamation Permit 80-244. Application for permit amendment 2 (Carlton Mill project:
add lower heap leach pad (Pad 2) and ponds on top of old tailings impoundment.)
Cripple Creek and Victor Gold Mining Company. 1986 (February 21). Victory Project: Application
for Regular 112 Permit. Approved as permit 86-024 on April 29, 1986. (Includes associated
reports and correspondence.)
Cripple Creek and Victor Gold Mining Company. 1987 (February 23). Victory Project, Permit 86-
024: Application for Technical Revision 2: expand pad 3 to design size to accommodate 1987
operations. (Presumed approved with TR 2, no correspondence obtained.)
Cripple Creek and Victor Gold Mining Company. 1987a (February 23). Carlton Project, Permit 80-
244: Application for Technical Revision 1: increase height or expand area of Pad 2, add
additional water storage capacity for 1987 operations. (Includes July 14 letter clarifying pad
options and Dames & Moore letters on proposed actions.)
Cripple Creek and Victor Gold Mining Company. 1987b (February 23). Victory Project, Permit 86-
024: Application for Technical Revision 3: actually a revision to TR 2 (2/23/87). Includes
June 2, 1987, approval letter from MLRD.
Cripple Creek and Victor Gold Mining Company. 1987 (April 27). Letter from C.A. Tapp,
Resident Manager, to A. Baldridge, Colorado Mined Land Reclamation Division. Carlton Mill
Pads, Permit 80-244: Description of April 20 spill of cyanide solution.
Cripple Creek and Victor Gold Mining Company. 1987 (July 17). Victory Project, Permit 86-024:
Application for Amendment 1: Construct additional heap leach pad (Pad 4) and ponds. Includes
October 28, 1987, approval letter from MLRD.
Cripple Creek and Victor Gold Mining Company. 1987 (August 12). Victory Project, Permit 86-
024: Application for Amendment 2: Add Portland Pit open pit mine to permitted operations
(Presumed approved, no correspondence obtained).
Cripple Creek and Victor Gold Mining Company 1987 (November 3). Letter from C.A. Tapp,
Manager, to A. Baldridge, Colorado Mined Land Reclamation Division. Carlton Project,
Permit 80-244: Description of October 8 spill of barren leach solution.
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Site Visit Report: Nerco Minerals Cripple Creek
Cripple Creek and Victor Gold Mining Company, 1987 (November 19). Letter from C.A. Tapp,
Manager, to A. Baldridge, Colorado Mined Land Reclamation Division. Carlton Project,
Permit 80-244: Description of repairs to primary liner of Pad 1 following detection of fluids in
leak detection system.
Cripple Creek and Victor Gold Mining Company. 1987 (November 20). Letter from C. Gerity,
Manager of Mining, to A. Baldridge, Colorado Mined Land Reclamation Division. Carlton
Project, Permit 80-244: Application for Technical Revision 2 (Rehabilitation of Carlton Mill for
carbon-in-leach recovery of gold from high-grade ore and placement of tailings on heap leach
Pad 1). Includes Dames & Moore letter of November 5, 1985 detailing geotechnical
engineering study results.
Cripple Creek and Victor Gold Mining Company. 1987 (December 8). Victory Project, Permit 86-
024: Application for Amendment 3: Revised plans for Pad 4 approved in Amendment 1.
(Presumed approved, no correspondence obtained.)
Cripple Creek and Victor Gold Mining Company. 1987 (December 18). Letter from C.A. Tapp,
Manager, to A. Baldrige, Colorado Mined Land Reclamation Division. Victory Project, Permit
86-024: Documented conversations and provided history of leak in primary liner of Pad 3
(solution in leak detection pipe).
Cripple Creek and Victor Gold Mining Company. 1988 (February 22). Letter from C. Gerity, to
J.T. Doerfer, Colorado Mined Land Reclamation Division. Carlton Mill Project, Permit 80-
244, Amendment 3: Response to MLRD adequacy letter of 2/9/88 on Amendment 3
application. Includes Dames & Moore letter dated 2/22/88 that provided responses to some
items.
Cripple Creek and Victor Gold Mining Company. 1988 (May 31). Victory Project, Permit 86-024:
Application for Technical Revision 4: Construct haulage road across Pad 3. (Includes July 7,
1988, MLRD approval letter.)
Cripple Creek and Victor Gold Mining Company. 1988a (May 31). Carlton Mill Project, Permit 80-
244: Application for Technical Revision 3. Change in construction of leak detection system in
expansion of Pad 2 approved in Amendment 3. Includes Dames & Moore letter of 5/19/88
describing actual construction.
Cripple Creek and Victor Gold Mining Company. 1988 (July 21). Letter from C.A. Tapp,
Manager, to J. Doerffer, Colorado Mined Land Reclamation Division. Victory Project, Permit
86-024: Notice of errant blast in Portland Pit.
Cripple Creek and Victor Gold Mining Company. 1988 (August 22). Letter from A. Tapp, Manager
of Mining and Development, to J. Doerffer, Colorado Mined Land Reclamation Division.
Victory Project, Permit 86-024: Description of August 12 cyanide spill.
Cripple Creek and Victor Gold Mining Company. 1988 (September 20). Letter from C. Gerity, to
C.M. Farrell, Colorado Mined Land Reclamation Division. Victory Project, Permit 86-024:
Transmittal of soil sampling results from August 12 cyanide spill.
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Site Visit Report: Nerco Minerals Cripple Creek
Cripple Creek and Victor Gold Mining Company. 1990 (February 12). Letter from E.T. Hunter,
Project Manager, to J. Doerfer, Colorado Mined Land Reclamation Division. Victory Project,
Permit 86-024: Notice of January 9 spill of cyanide solution on Pad 4.
Cripple Creek and Victor Gold Mining Company. 1990 (November 5). Letter from J.P. Rovedo,
Safety/Environmental Engineer, to J. Doerfer, Colorado Mined Land Reclamation Division.
Victory Project, Permit 86-024: Notice of November 5 spill of cyanide solution on Pad 4.
Cripple Creek and Victor Gold Mining Company. 1991 (January 23). Letter from J.P. Rovedo,
Safety/Environmental Engineer, to J. Doerfer, Colorado Mined Land Reclamation Division.
Permit M-77-367: Proposed responses to NOV M-88-013 upon succession of CC&V as
operator of Globe Hill and '76 Project.
Cripple Creek and Victor Gold Mining Company. 1992 (March 6). Letter from E.T. Hunter to C.
Mount, Colorado Mined Land Reclamation Division. Permit M-81-134: Submission of internal
company memoranda describing February 26 pregnant solution spill incident and February 29
ore slide and pregnant solution spill.
Dames & Moore. 1984 (December 12). Report, Geotechnical Engineering Studies, Stability of Mine
. Waste Dumps and Tailings Disposal Piles, Victor Mine, Cripple Creek, Colorado, for Nerco
Minerals Co. Prepared for Nerco Minerals Company (Job No. 12077-005-14). Submitted to
Colorado Mined Land Reclamation Division on December 26, 1984.
Dames & Moore. 1985. Report, Subsurface Exploration and Preliminary Design, Proposed Lower
Carlton Heap Leach, Carlton Mill, Near Victor Colorado, for Cripple Creek and Victor Gold
Mining Company. Prepared for CC&V. Submitted to Colorado Mined Land Reclamation
Division with application for Permit 80-244, Amendment 2, on January 16, 1986.
Dames & Moore. 1989 (March 16). Report; As-Built Construction; Heap Leach Pad No. 4 Near
Victor, Colorado; for Cripple Creek and Victor Gold Mining Company. Prepared for Texasgulf
Minerals and Metals, Inc. (Job No. 09077-033-19). Submitted to Colorado Mined Land
Reclamation Division on March 30, 1989.
Dayspring Mining Corporation. 1988 (October 28). Letter from B. Mountford, President, to F.
Banta, Colorado Mined Land Reclamation Division. (Response to MLRD letter of September
22 and September 21 Notice of Violation M-88-013 and Cease and Desist Order.)
Geddes, MacDougall, Geddes & Paxton (attorneys for Newport Minerals). 1981 (September 15).
Letter from M.E. MacDougall to P.H. Evans, Colorado Mined Land Reclamation Division. ,
Permit 77-367: Response to MLRD letter of September 2 letter transmitting two NOVs and a
Cease and Desist Order.
Geddes, MacDougall, Geddes & Paxton (attorneys for Newport Minerals). 1981 (November 25).
Letter from M.E. MacDougall to P.H. Evans, Colorado Mined Land Reclamation Division.
Permit 77-367: Request for 9/21/81 technical revision to be incorporated into Amendment 2 and
agreement to reline the '76 Project pond, fence the area, and monitor effluents at closure.
4-69
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Site Visit Report: Nerco Minerals Cripple Creek
Gold Resources Joint Venture. 1977 (September 30). Application for Mining and Reclamation
Permit, Regular (112) Permit Application Form. Submitted to Colorado Mined Land
Reclamation Board. Application for Globe Hill project. Subsequently approved as Permit M-
77-367.
Gold Resources Joint Venture. 1978 (June 5). Application for Amendment 1, Permit 77-367;
Regular (112) Permit Application Form. Submitted to Colorado Mined Land Reclamation
Board. Application to add 11.34 acres to Globe Hill project.
Lewis, A. 1982 (October). "Producing Gold for $160/Tr Oz in Victor, Colorado." Engineering and
Mining Journal: pp. 102-105.
Nerco Minerals Company. 1984 (June 19). Letter from M.L. Clark, Vice President for Operations,
to D.C. Shelton, Director, Colorado Division of Mined Land Reclamation. Permit 81-134:
June 22, 1984, application for Amendment 2 following succession of Nerco as operator. (Grade
and deactivate tailings area 2, extend area 1 and build collection ponds, new waste rock disposal
area, add Globe Hill heap to this permit). Includes Nerco and MLRD correspondence, including
revisions to application dated 9/20/84 and 9/21/84. Approved by MLRD 10/17/84.
Nerco Minerals Company. 1984 (August 22). Letter from J.R. Woodward, Senior Permitting
Engineer, to B. Janes, Reclamation Specialist, Colorado Division of Mined Land Reclamation.
Permit 81-134: Request for Technical Revision 2~replace 3.2 undisturbed acres for 3.2 acres
for use as on-site haul road.
Nerco Minerals Company. 1985 (April 25). Letter from T.J. Schamberger, Chief Engineer, to P.C.
Saletta, Colorado Division of Mined Land Reclamation. Permit 81-134: Response to MLRD
inspection report on March 20-21 inspection of Victor Mine (MLRD 3/20-21/85).
Nerco Minerals Company. 1985 (May 9). Letter from T.J. Schamberger, Chief Engineer, to P.C.
Saletta, Inspector, Colorado Division of Mined Land Reclamation. Victor Mine Permit 81-134:
Letter advising of as-built modification to tailings liner construction.
Nerco Minerals Company. 1985 (October 28). Annual Report to Colorado Mined Land Reclamation
Division for the year 1985. Permit 81-134.
Nerco Minerals Company. 1986 (January 2). Letter from T.J, Schamberger, Engineering
Superintendent, to D.C. Shelton, Director, Colorado Division of Mined Land Reclamation.
Permit 81-134: Certification of compliance with Cease and Desist Order dated December 20.
(Tailings deposition on Victor Mine tailings pile west of Rangeview Road had been stopped.)
Nerco Minerals Company. 1986 (January 24). Letter from T.J. Schamberger, Engineering
Superintendent, to D.C. Shelto... Director, Colorado Division of Mined Land Reclamation.
Permit 81-134: Notice of temporary cessation of production at Victor Mine.
Nerco Minerals Company. 1986 (February 12). Letter from T.J. Schamberger, Engineering
Superintendent, to C. Farrell, Colorado Mined Land Reclamation Division. Permit M-81-134:
Application for Technical Revision 4. (Revised tailings disposal system after tailings slough on
November 6, 1985.)
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Site Visit Report: Nerco Minerals Cripple Creek
Nerco Minerals Company. 1986 (March 10 and March 14). Letters from E. Hunter, Senior Project
Engineer, to C. Farrell, Colorado Mined Land Reclamation Division. Permit M-81-134,
Technical Revision 4: Responses to Colorado Mined Land Reclamation Division letter of
February 20 requesting clarification of items in Technical Revision 4.
Nerco Minerals Company. 1987 (January). Annual Report to Colorado Mined Land Reclamation
Division for the year 1986, October 1, 1985 - September 30, 1986. Permit 81-134.
Nerco Minerals Company. 1987 (January 6). Letter from E. Hunter, Senior Project Engineer, to C.
Farrell, Colorado Mined Land Reclamation Division. Permit 81-134: Application for Technical
Revision 5. (Modification of method of transfer of run-off from tailings area to collection pond:
remove failed 18-inch pipe and use lined open ditch.)
Nerco Minerals Company. 1987 (January 29). Letter from E. Hunter, Senior Project Engineer, to
C. Farrell, Colorado Mined Land Reclamation Division. Permit 81-134, Technical Revision 5:
Response to Colorado Mined Land Reclamation Division letter of January 12 requesting
clarification of specific items prior to Board consideration of application for Technical Revision
5.
Nerco Minerals Company. 1987 (October 13). Annual Report to Colorado Mined Land
Reclamation Division for the year 1987, October 1, 1986 - September 30, 1987. Permit 81-134.
Includes addendum submitted January 1988.
Nerco Minerals Company. 1988 (September). Annual Report to Colorado Mined Land Reclamation
Division for the year 1988, October 1, 1987 - September 30, 1988. Permit 81-134. Includes
addendum submitted November 3.
Nerco Mineral Company. 1989 (March 30). Letter from E. Hunter, Senior Project Engineer, to C.
Farrell, Colorado Mined Land Reclamation Division. Permit 81-134: Sampling results from
Globe Hill heap run-off pond.
Nerco Minerals Company. 1989 (September). Annual Report to Colorado Mined Land Reclamation
Division for the year 1989, October 1, 1988 - September 30, 1989. Permit 81-134. Includes
addendum submitted November 17, 1989.
Nerco, Inc. 1990 (August 22). Letter from J.F. Resch, Jr., Director of Insurance and Risk
Management, to D. Heyer, Colorado Mined Land Reclamation Division. Notice of Nerco
purchase of Texasgulf Minerals and Metals from ELF Aquitane, Inc. Cited were MLRD
permits 80-244, 82-214, 86-009, 86-024, 88-025, 88-064, 88-099, 88-097, 88-097, 88-100, and
88-098.
Nerco Minerals Company. 1990 (September 11). Letter from J.P. Re-redo, Safety/Environmental
Engineer, to J. Doerfer, Colorado Mined Land Reclamation Division. Letter informed MLRD
of pilot test using two truck loads of waste rock as aggregate for asphalt or other uses.
Nerco Minerals Company. 1990 (September 17). Letter from J.P. Rovedo, Safety/Environmental
Engineer, to D. Hernandez, Colorado Mined Land Reclamation Division. Permit 81-134:
Request for removal of temporary cessation notice (approved by Mined Land Reclamation Board
on October 17). Re-activation of Victor Mine.
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Site Visit Report: Nerco Minerals Cripple Creek
Nerco Minerals Company. 1990 (October 2). Letter from J.P. Rovedo, Safety/Environmental
Engineer, to D. Hernandez, Colorado Mined Land Reclamation Division. Permit 81-134:
Response to August 14, 1990 inspection report. Also includes October 8 letter.
Nerco Minerals Company. 1990 (October 24). Letter from J.P. Rovedo, Safety/Environmental
Engineer, to D. Hernandez, Colorado Mined Land Reclamation Division. Permit 81-134:
Response to August 14, 1990 inspection report.
Nerco Minerals Company. 1990 (October). Annual Report to Colorado Mined Land Reclamation
Division for the year 1990, October 1, 1989 - September 30, 1990. Permit M-81-134.
Nerco Minerals Company. 1991 (May 10). Letter from J.P. Rovedo, Safety/Environmental
Engineer, to D. Hernandez, Colorado Mined Land Reclamation Division. Permit M-81-134:
Application for Amendment to Regular Operation Reclamation Permit, Victor Mine. (Add new
Ironclad pad, enlarge pond 4A, add new storage pond 4C).
Newport Minerals, Inc. 1979 (March 29). Request to Succeed Operator at an Uncompleted
Operation. Submitted to Colorado Mined Land Reclamation Board. Permit 77-367: Newport
Minerals to succeed Gold Resources Joint Venture as operator of Globe Hill project.
Newport Minerals, Inc. 1981 (September 14). Application for Amendment 2; Permit 77-367;
Regular (112) Permit Application Form. Submitted to Colorado Mined Land Reclamation
Board. Application to add 14.2 acre '76 site to Globe Hill permit.
Newport Minerals, Inc. 1985 (June 24). Letter from V.F. Reilly to P.C. Saletta, Colorado Mined
Land Reclamation Division. Results of 4/9/85 sampling of Globe Hill and other ponds.
Newport Minerals, Inc. 1985 (September 24). Letter from V.F. Reilly to P.C. Saletta, Colorado
Mined Land Reclamation Division. Results of 7/19/85 sampling of Globe Hill and other ponds.
Newport Minerals, Inc. 1986 (July 3). Letter from V.F. Reilly to C. Farrell, Colorado Mined Land
Reclamation Division. Results of 6/17/86 sampling of '76 Project ponds (Permit 77-367).
Newport Minerals, Inc. 1986 (July 18). Letter from V.F. Reilly to C. Farrell, Colorado'Mined
Land Reclamation Division. Results of June 1986 sampling of Forest Queen/2A ponds. (Permit
77-367).
Pontius, J.A. and R.A. Butts. 1991. "Geology and Gold Mineralization of the Cresson Deposit.
Cripple Creek, Colorado." Presented at the 97th Annual Northwest Mining Association
convention, Spokane, Washington, December 4-6, 1991.
Pikes Peak Mining Company. 1990 (April 27). Letter from E. Hunter to L. Oehler, Colorado
Mined Land Reclamation Board. Victory Project, Permit 86-024 and Carlton Mill Project.
Permit 80-244: Application for Technical Revisions to modify monitoring requirements.
(Includes MLRD and CC&V correspondence, culminating in MLRD letters advising of Board
approval.)
Pontius, J.A. and R.A. Butts. 1991 (December). "Geology and Gold Mineralization of the Cresv..n
Deposit, Cripple Creek, Colorado. Presented at the 97th Annual Northwest Mining Assouan;-n
Convention; Spokane, Washington; December 4-6, 1991.
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Site Visit Report: Nerco Minerals Cripple Creek
Reilly, V.F. 1986 (April 6). Letter from V.F. Reilly, PNT Mining Inc., to E. Bischoff, Colorado
Mined Land Reclamation. Permit 77-367: Inquiry as to reclamation requirements and
"environmental obligations" of the Globe Hill permittee. (Includes synopsis of Globe Hill
permit transactions and reclamation requirements.)
Silver State Mining Corporation. 1981 (March 25). Application for Permit for Regular Mining
Operation (for Victor Project - Ironclad Pit). Subsequently approved (on September 8, 1981) as
Permit 81-134.
Silver State Mining Corporation. 1983 (May 26). Application for Amendment 1 to Victor Mine
Permit 81-134: Enlarge pit, add waste rock dump and new tailings disposal area to permit.
Includes May 1983 and January 1984 revisions to application and September 1983 plan for
reclamation of waste rock dumps and tailings areas. Approved May 1984 (MLRD 5/30/84).
Silver State Mining Corporation. 1983. Annual Report [for 1983]. Permit 81-134.
Silver State Mining Corporation. 1983 (December 7). Victor Mine, Permit 81-134: Application for
Technical Revision 1. (Add vehicle maintenance building, enlarge buildings and parking lot.
Includes MLRD approval letter dated January 11, 1984.
Silver State Mining Corporation. 1984 (April 13). Letter from W.R. Reid, President/CEO, notifying
vendors of imminent joint venture between Silver State and Nerco Minerals Company, with
Nerco becoming Victor Mine operator.
State of Colorado, Department of Health, Water Quality Control Division. 1985 (November 6).
Notes of Gary Soldano (?) on telephone notification by Teller County Health Services of a
cyanide spill at Victor Mine.
State of Colorado, Department of Health, Water Quality Control Division. 1992 (March 12).
Authorization to Discharge Under the Colorado Discharge Permit System, Permit No.
CO0024562. NPDES permit issued to Cripple Creek and Victor Gold Mining Company,
authorizing discharge from Carlton Tunnel.
State of Colorado, Mined Land Reclamation Division. 1979 (April 12). Letter from J.L.
Schmieding, Reclamation Specialist, to M.H. MacDbugall, attorney for Newport Minerals. Inc
Transmittal letter for permit 77-367. (Including copy of permit and application).
State of Colorado, Mined Land Reclamation Division. 1981 (August 14). Letter from J.L.
Schmieding, Reclamation Specialist, to Silver State Mining Corporation. Notice that Silver Suie
was conducting an unpermitted gold operation and that Board would hold a hearing on August
26, 1981.
State of Colorado, Mined Land Reclamation Division. 1981 (September 2). Letter from P.H. Ewns
Reclamation Specialist, to T. Downing, Newport Minerals, Inc. Transmittal letter for two
NOVs and a Cease and Desist Order. (For cyanide operations at unpermitted '76 site and
undescribed cyanide operations [Forest Queen and 2A pads] at permitted Globe Hill site.)
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Site Visit Report: Nerco Minerals Cripple Creek
State of Colorado, Mined Land Reclamation Division. 1981 (September 8). Letter from M. Stanton,
Reclamation Specialist, to B. Reid, Silver State Mining Company. Permit 81-134: Notice of
Board approval of permit application dated March 25, 1981. Includes prior correspondence,
NOV and Cease and Desist order concerning disturbance before permit issuance.
i
State of Colorado, Mined Land Reclamation Division. 1981 (December 21). Letter from P.H.
Evans, Reclamation Specialist, to T. Downing, Newport Minerals, Inc. Permit 77-367: Notice
of December 16 Board approval of Amendment 2 (add '76 site to permit) and technical revision
(add Forest Queen and 2A leach pad to permitted operations).
State of Colorado, Mined Land Reclamation Division. 1982 (March 26). Letter from P.H. Evans,
Reclamation Specialist, to T. Downing, Newport Minerals, Inc. Permit 77-367, Globe Hill
Project: Approval for amendment 3 (adding waste dumps to permit area for use as ore).
Includes application and related correspondence.
State of Colorado, Mined Land Reclamation Division. 1982 (April 18). Mining and Reclamation
Permit M-82-214. Issued to Pioneer Sand Company for removal of rock from (lower) Mary
McKinney Dump for use as decorative rock. Property and permit transferred to Cripple Creek
and Victor Gold Mining Company in 1986. Includes application and correspondence.
State of Colorado, Mined Land Reclamation Division. 1982 (September 27). Letter from M.
Stanton, Reclamation Specialist, to T. Downing, Newport Minerals, Inc. Permit 77-367, Globe
Hill Project: notice of Board approval for (unnumbered) Technical Revision (add 40,000 square
feet to existing heapto receive ore from old mine dumps). Includes application and
correspondence.
State of Colorado, Mined Land Reclamation Division. 1984 (May 30). Letter from C. Russell,
Reclamation Specialist, to B. Hester, Newport Minerals Inc. Globe Hill Permit 77-367: Notice
of Board approval of amendment 4 (storage area for tailings from Silver State Mining Company
mill). Includes application for amendment and related correspondence.
State of Colorado, Mined Land Reclamation Division. 1984 (June 20). Letter from M.S. Loye,
Reclamation Specialist, to E.T. Hunter, Silver State Mining Company. Permit 81-134: Notice
of June 27-28 .Board .consideration of request for transfer of permit from Silver State Mining
Company, to Nerco Minerals Company (pending payment of fees).
State of Colorado, Mined Land Reclamation Division. 1984 (September 28). Letter from C. Russell,
Reclamation Specialist, to B. Hester, Newport Minerals Inc. Permit 77-367: Notice of Board
approval of Technical Revision 4 (disposal of rinsed "disused" cyanide containers in an area to
be covered by waste rock). Includes application for revision and related correspondence.
State of Cc'orado, Mined Land Reclamation Division. 1984 (October 11). Permit 81-134: Notice of
Inspection and Inspection Report on October 11 inspection of Victor Mine by P.C. Saletta.
State of Colorado, Mined Land Reclamation Division. 1984 (October 17). Permit 81-134: Notice of
Board approval of Amendment 1 (Nerco 6/20/84). Increase in bond to $373,948.
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Site Visit Report: Nerco Minerals Cripple Creek
State of Colorado, Mined Land Reclamation Division. 1985 (March 1). Letter from P.C Saletta,
Hydrologist/Geological Engineer, to B. Jacobs, Nerco Minerals Company. Permit 81-134:
Notice of Board approval of Technical Revision 3 to Victor Mine permit. (Relocation of waste
dump: Exchange 11.2 undisturbed acres designated for waste dump for another 11.2 acres
where dump will occur.) Includes application for Technical Revision.
State of Colorado, Mined Land Reclamation Division. 1985 (March 20-21 and June 5). Notices of
Inspection and Inspection Reports on March 20-21 and June 5 inspections of Victor Mine
(Permit 81-134) by D. Berry, C. Farrell, and P.C. Saletta (March 20-21) and P.C. Saletta (June
5). .
State of Colorado, Mined Land Reclamation Division. 1985 (May 30). Letter from P.C. Saletta,
Hydrologist/Geological Engineer, to C. Gerity, Texasgulf Minerals and Metals, Inc. Permit 80-
244, Carlton Mill project: Notice of Board approval for amendment 1 (add heap leach pads and
ponds).
State of Colorado, Mined Land Reclamation Division. 1985 (June 11). Notice of Inspection and
Inspection Reports on June 11 inspection of Victor Mine by P.C. Saletta.
State of Colorado, Mined Land Reclamation Division. 1985 (July 1). Letter from P.C. Saletta,
Hydrologist/Geological Engineer, to K. Ennis, Newport Minerals, Inc. Permit 77-367, Globe
Hill Project: Notice of Board approval for amendment 5 (enlarge pit, construct and operate vat
leach facilities). Includes application and related correspondence.
State of Colorado, Mined Land Reclamation Division. 1985a (November 6). Memorandum to file by
M.S. Loye, Reclamation Specialist, on notification by Nerco Minerals of tailings failure and
resulting spill of "seep water" and other telephone conversations during the day (with EPA and
Colorado Department of Health). Permit 81-134.
State of Colorado, Mined Land Reclamation Division. 1985b (November 6). Notice of Inspection
and Inspection Repon on November 6 inspection of Victor Mine by A.C. Baldridge, P. Saletta,
and C. Farrell. (Following notification of tailings pile failure on same date.)
State of Colorado, Mined Land Reclamation Board, 1985 (December 20). Notice of Violation M-85-
081 and Cease and Desist Order, issued to Nerco Minerals Company. (Issued for inadvertent
violations resulting from a November 6, 1985, tailings failure and resulting runoff-collection
pond spill at Victor Mine (Permit 81-134) . Assessed but waived $100 civil penalty.) Includes
MLRD and Nerco correspondence, logs, analytical results related to tailings pile failure and
November and December Board meetings and hearings (and MLRD notes on meetings).
State of Colorado, Mined Land Reclamation Division. 1986 (January 2). Letter from C. Farrell,
Reclamation Specialist, to E. Hunter, Ne-co Minerals Company. Permit 81-134: Request for
clarification of items in report on November 6, 1985, tailings failure submitted by Nerco in
preparation for anticipated Technical Revision.
State of Colorado, Mined Land Reclamation Division. 1986 (January 28). Letter from C.M. Farrell.
Reclamation Specialist, to T.J. Schamberger, Nerco Minerals Company. Permit 81-134: Notice
that Nerco's January 26, 1986, Notice of Temporary Cessation satisfied the requirements of
Colorado Minerals Rules and Regulations Number 1.62.
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Sire Visit Report: Nerco Minerals Cripple Creek
State of Colorado, Mined Land Reclamation Division. 1986 (January 29). Notice of Inspection and
Inspection Report on January 29 inspection of Victor Mine (Permit 81-134) by A. Baldridge, K.
Hellner, M. Loye, and E. Bischoff.
State of Colorado, Mined Land Reclamation Division. 1986 (February 20). Letter from C. Farrell,
Reclamation Specialist, to T. Schamberger, Nerco Minerals Company. Permit 81-134,
Technical Revision 4: Acknowledgement of receipt of Technical Revision 4 on February 14 and
request for clarification of specific items prior to Board consideration.
State of Colorado, Mined Land Reclamation Division. 1986 (March 24). Letter from A.C.
Baldridge, Reclamation Specialist, to C. Gerity, Cripple Creek and Victor Gold Co. Permit 80-
244, Carlton.Mill project: Notice of Board conditional approval for amendment 2 (add Pad 2
and ponds). Conditional upon liner verification, as-built submissions, test plots, ground-water
monitoring, etc.
State of Colorado, Mined Land Reclamation Division. 1986 (March 25). Letter from C.M. Farrell,
Reclamation Specialist, to E. Hunter, Nerco Minerals Company. Permit M-81-134, Technical
Revision 4: Notice of Board approval of Nerco's February 14, 1986, application for Technical
Revision 4 and incorporation of terms into permit. (On-site corrective action to tailings piles
and ponds.)
State of Colorado, Mined Land Reclamation Division. 1986 (March 31). Letter from D.C. Shelton,
Director, to Cripple Creek and Victor Mining. Permit M-86-009: Notice of March 20 approval
of 112 permit application for Lillie Project. Includes original and other applications and
correspondence.
State of Colorado, Mined Land Reclamation Division. 1986 (May 22). Letter from C.M. Farrell,
Reclamation Specialist, to V.F. Reilly, PNT Mining, Inc. Response to Reilly letter of April 15
summarizing Permit 77-367. (Included summary of reclamation requirements.)
State of Colorado, Mined Land Reclamation Division. 1986 (July 1). Letter from C. Farrell,
Reclamation Specialist, to B. Knocks, Newport Minerals, Inc. Permit M-77-367: Notice of
Board issuance of NOV M-86-036 and Cease and Desist Order for Globe Hill/'76 Project.
(Includes NOV and Order; also includes June 3, 1986, letter from D.C. Shelton, MLRD, to B.
' Knocks, summarizing earlier inspections and Newport's failure to respond).
State of Colorado, Mined Land Reclamation Division. 1986 (July 10). Notice of Inspection and
Inspection Report on July 10 inspection of Victor Mine (permit 81-134) by C. Farrell.
State of Colorado, Mined Land Reclamation Board. 1986 (September 4). Notice of Violation M-86-
049 and Cease and Desist Order, Permit M-77-367. (For noncompliance with July 1, 1986,
NOV M-86-036 and Order).
State of Colorado, Mined Land Reclamation Division. 1986 (September 25). Letter from C. Farrell.
Reclamation Specialist, to B. Horn, Dayspnng Mining Corporation. Permit M-77-367: Notice
of Board approval for Daysprings Mining Corporation to succeed Newport Minerals, Inc., as
operator of Globe Hill Project.
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Sire Vistf Report: Nerco Minerals Cripple Creek
State of Colorado, Mined Land Reclamation Division. 1986 (September 29). Letter from D.C.
Shelton, Director, to G.P. Reed, Newport Minerals, Inc. Notice of Board issuance of NOV M-
86-0057 and Cease and Desist Order for Globe Hill/'76 Project. Issued to Newport Minerals
for noncompliance with NOVs M-86-036 (July 1, 1986) and M-86-049 (September 4, 1986) and
associated Cease and Desist Orders. (Includes NOV and Order; notes Dayspring Mining
Corporation succession as permittee.)
State of Colorado, Mined Land Reclamation Division. 1987a (January 12). Letter from C. Farrell,
Reclamation Specialist, to E. Hunter, Nerco Minerals Company. Permit 81-134, Technical
Revision 5: notice of completeness for application for Technical Revision 5 and request for
clarification of specific items prior to Board consideration.
State of Colorado, Mined Land Reclamation Division. 1987b (January 12). Memorandum to File
from A. Baldridge, Reclamation Specialist. Record of telephone conversation with A. Tapp,
Cripple Creek and Victor Gold Mining Company, concerning water balance at Victory and
Carlton Mill ponds.
State of Colorado, Mined Land Reclamation Division. 1987 (February 26). Letter from C. Farrell,
Reclamation Specialist, to E. Hunter, Nerco Minerals Company. Permit 81-134, Technical
Revision 5: Notice of February 25 Board approval of Technical Revision TR-05 and
incorporation of terms of revision into permit.
State of Colorado, Mined Land Reclamation Division. 1987 (March 26). Letter from A. Baldridge,
Reclamation Specialist, to C. Gerity, Cripple Creek and Victor Gold Co. Carlton Project,
Permit 80-244, Technical Revision 1: Notice of March 25 Board approval of Technical
Revision 1 and additional permit stipulations.
State of Colorado, Mined Land Reclamation Division. 1987 (October 22). Minerals Programs
Inspection Report for Victor Mine inspection conducted October 22, 1987, by C.M. Farrell.
State of Colorado, Mined Land Reclamation Division. 1988 (January 25). Letter from J.T. Doerfer,
Reclamation Specialist, to C. Gerity, Cripple Creek and Victor Gold Co. Carlton Project,
Permit 80-244, Technical Revision 2: Notice of January 21 Board approval of Technical
Revision 2 (placement of mill tailings on Pad 1). Includes MLRD staff notes.
State of Colorado, Mined Land Reclamation Division. 1988 (February 9). Letter from J.T. Doerfer,
Reclamation Specialist, to C. Gerity, Cripple Creek and Victor Gold Co. Carlton Project,
Permit 80-244, Amendment 3: Results of adequacy review of amendment application and
request for additional information. (Original application not obtained.)
State of Colorado, Mined Land Reclamation Division. 1988 (February 26). Letter from J.T.
Doerfer, Reclamation Specialist, to C. Gerity. Cripple Creek and Victor Gold Co. Carlton
Project, Permit 80-244, Amendment 3: Notice of February 24 Board approval of Amendment 3
(expansion of Pad 2 on adjacent hillside). Included stipulation that pre-construction notice be
provided.
State of Colorado, Mined Land Reclamation Division 1988a (May 16). Letter from F.R. Banta.
Director, to C. Gerity, Texasgulf Minerals and Metals. Permit M-88-025: Notification of May
12 Board approval of Anchoria Leland Mine Dump 110 permit. Includes permit application and
correspondence.
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Site Visit Report: Nerco Minerals Cripple Creek
State of Colorado, Mined Land Reclamation Division. 19885 (May 16). Letter from F.R. Banta,
Director, to C. Gerity, Texasgulf Minerals and Metals. Permit M-88-026: Notification of May
12 Board approval of Chicago Tunnel 110 permit. Includes permit application and
correspondence.
State of Colorado^ Mined Land Reclamation Division. 1988 (July 7). Letter from J.T. Doerfer,
Reclamation Specialist, to C. Gerity, Cripple Creek and Victor Gold Co. Charlton [sic] Project,
Permit 80-244: Notice of July 7 Board approval of Technical Revision 3 (change in liner design
of Pad 2 expansion approved in Amendment 3).
State of Colorado, Mined Land Reclamation Division. 1988 (August 16). Minerals Program
Inspection Report on August 16, 1988, inspection of Victory Pad (#3), Permit 86-024, by C.
Farrell and F.R. Banta. (Following cyanide spill on August 12.)
State of Colorado, Mined Land Reclamation Division. 1988 (September 6). Memorandum to MLRD
files from J.T. Doerfer, Reclamation Specialist. Victory Project, Permit 86-024:
Documentation of August 15 telephone conversation between J.T. Doerfer and A. Tapp, Cripple
Creek and Victor Gold Mining Company, concerning cyanide spill on August 12.
State of Colorado, Mined Land Reclamation Division. 1988 (September 13). Letter from F.R.
Banta, Director, to B. Mountford, Dayspring Mining Corporation. Permit 77-367:
Transmission of September 9 Minerals Programs Inspection Report for Globe Hill ['76 Project]
and notice of Board hearing on possible violations.
State of Colorado, Mined Land Reclamation Division. 1988 (September 22). Letter from F.R.
Banta, Director, to B. Mountford, Dayspring Mining Corporation. Permit 77-367:
Transmission of Notice of Violation M-88-013 and Cease and Desist Order arising from
September 9 inspection of Globe Hill ('76 Project).
State of Colorado, Mined Land Reclamation Division. 1988 (September 22). Letter from F.R.
Banta, Director, to C. Gerity, Cripple Creek and Victor Gold Mining Company. Victory
Project, Permit 86-024: Transmission of Notice of Violation M-88-015 arising from August 12
cyanide spill. (Includes August 29 notice of Board hearing on possible violation.)
State of Colorado, Mined Land Reclamation Division. 1988 (October 26). Letter from F.R. Banta,
Director, to C. Gerity, Texasgulf Minerals and Metals. Permit M-88-064: Notification of
October 5 Board approval of Gold Star Pit 112 permit. Includes permit application and
correspondence.
State of Colorado, Mined Land Reclamation Division. 1988 (November 15). Letter from F.R.
Banta, Director, to B. Mountford, Dayspring Mining Corporation. Permit 77-367:
Transmission of re-issued Notice of Violation M-88-013 and Cease and Desist Order, originally
issued September 21; and order of payment of civil penalty.
State of Colorado, Mined Land Reclamation Division. 1988a (November 28). Letter from F.R.
Banta, Director, to T. Aragon, Cripple Creek and Victor Gold. Permit M-89-096: Notification
of November 21 Board approval of Ocean Wave Mine Dump 110 permit. Includes permit
application and correspondence.
4-78
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Site Visit Report: Nereo Minerals Cripple Creek
State of Colorado, Mined Land Reclamation Division. 1988b (November 28). Letter from F.R.
Banta, Director, to T. Aragon, Cripple Creek and Victor Gold. Permit M-89-097: Notification
of November 21 Board approval of Tornado/Raven Mine Dumps 110 permit. Includes permit
application and correspondence.
State of Colorado, Mined Land Reclamation Division. 1988c (November 28). Letter from F.R.
Banta, Director, to T. Aragon, Cripple Creek and Victor Gold. Permit M-88-098: Notification
of November 21 Board approval of Blue Flag Mine Dump 110 permit. Includes permit
application and correspondence.
State of Colorado, Mined Land Reclamation Division. 1988d (November 28). Letter from F.R.
Banta, Director, to T. Aragon, Cripple Creek and Victor Gold. Permit M-89-099: Notification
of November 21 Board approval of Howard Mine Rock Dump 110 permit. Includes permit
application and correspondence.
State of Colorado, Mined Land Reclamation Division. 1988 (December 9). Letter from F.R. Banta,
Director, to T. Aragon, Cripple Creek and Victor Gold. Permit M-89-100: Notification of
November 21 Board approval of Index Mine Dump 110 permit. Includes permit application and
correspondence.
State of Colorado, Mined Land Reclamation Division. 1989 (April 21). Letter from J.T. Doerfer,
Reclamation Specialist, to T. Aragon, Cripple Creek and Victor Gold Co. Carlton Project,
Permit 80-244, Technical Revision 4: Notice of April 17 Board approval of Technical Revision
4 (water balance information for 1989 operating year).
State of Colorado, Mined Land Reclamation Division. 1989 (July 14). Letter from L.D. Oehler,
Reclamation Specialist, to T.L. Aragon, Texasgulf Minerals and Metals. Permit M-89-A059:
Notification of July 14 Board approval of Rigi Mine Rock Dump 110 permit. Includes permit
application and correspondence.
State of Colorado, Mined Land Reclamation Division. 1989a (July 27). Letter from F.R. Banta,
Director, to C. Gerity, Texasgulf Minerals and Metals. Permit M-89-060: Notification of July
28 Board approval of Upper Mary McKinney Mine Dump 110 permit. Includes permit
application and correspondence, including reports on cribbing wall and closure report.
State of Colorado, Mined Land Reclamation Division. 1989b (July 27). Letter from F.R. Banta,
Director, to C. Gerity, Texasgulf Minerals and Metals. Permit M-89-061: Notification of July
28 Board approval of Hull City and Sacramento Mine Dumps 110 permit. Includes permit
application and correspondence.
State of Colorado, Mined Land Reclamation Division. 1990 (August 14). Minerals Programs
Inspection Report for Victor Mine (Permit 81-134) inspection conducted August 14, 1990, by
D.I. Hernandez.
State of Colorado, Mined Land Reclamation Division. 1990a (October 2). Letter from F.R. Banta,
Director, to J.P. Rovedo, Cripple Creek and Victor Gold. Permit M-90-109: Notification of
Director, to J.P. Rovedo, Cripple Creek and Victor Gold. Permit M-90-109: Notification of
October 1 Board approval of Bertha B/Maggie Mine Dumps 110 permit. Includes permit
application and correspondence.
4-79
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Site Visit Report: Nerco Minerals Cripple Creek
State of Colorado, Mined Land Reclamation Division. 1990b (October 2). Letter from F.R. Banta,
Director, to J.P. Rovedo, Cripple Creek and Victor Gbld. Permit M-90-110: Notification of
October 1 Board approval of Midget Mine Dump 110 permit. Includes permit application and
correspondence.
State of Colorado, Mined Land Reclamation Division. 1990c (October 2). Letter from F.R. Banta,
Director, to J.P. Rovedo, Cripple Creek and Victor Gold. Permit M-90-111: Notification of
October 1 Board approval of Moon Anchor Dump 110 permit. Includes permit application and
correspondence.
State of Colorado, Mined Land Reclamation Division. 1990 (October 29). Letter from D.
Hernandez, Reclamation Specialist, to J.P. Rovedo, Nerco Minerals Company. Permit M-81-
134: Notice of Board approval on October 17 of September 20 (dated September 17) request to
reactivate Victor Mine.
State of Colorado, Mined Land Reclamation Division. 1991 (January 29). Letter from J.T. Doerfer,
Reclamation Specialist, to J.P. Rovedo, Cripple Creek and Victor Gold Mining Company.
Permit M-77-367, NOV M-88-013: Approval of actions, proposed in letter of January 23, to
respond to NOV 88-013, upon succession of CC&V as operator (from Dayspring).
State of Colorado, Mined Land Reclamation Division. 1991 (February 6). Approval of Transfer of
Permit and Succession of Operators Application Form. (Pikes Peak Mining Company succeeded
Daysprings Mining Corporation as operator of Globe Hill/Bull Hill.)
State of Colorado, Mined Land Reclamation Division. 1991 (August 5). Minerals Programs
Inspection Report for Victor Mine (Permit 81-134) inspection conducted August 5, 1991, by T.
Schreiner.
State of Colorado, Mined Land Reclamation Division. 1991~(October 10). Letter from T.A.
Schreiner, Reclamation Specialist, to J.P. Rovedo, Pikes Peak Mining Company. Permit 77-
367, Globe Hill Mine: Notice of Board approval for Technical Revision 4 (Install double-lined
leach pad where existing Forest queen leach pad was currently in place). Includes application
and correspondence.
State of Colorado, Mined Land Reclamation Division. 1991 (November 7). Letter from D.L.
Bucknam, Acting Director, to E.T. Hunter, Cripple Creek and Victor Gold. Permit M-91-114:
Notification of November 6 Board approval of Clyde/Modoc Dump 110 permit. Includes permit
application and correspondence.
State of Colorado, Mined Land Reclamation Division. 1992 (February 27). Minerals Programs
Inspection Report for Victor Mine (Permit 81-134) inspection conducted February 27, 1992, by
C.B. Mount (following IroncLJ heap pregnant cyanide solution spill beginning on February 26).
State of Colorado, Mined Land Reclamation Division. 1992 (March 2). Minerals Programs
Inspection Report for Victor Mine (Permit 81-134) inspection conducted March 2, 1992, by
C.B. Mount and B. Keffelow (following Ironclad heap failure and solution flow).
4-80
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Sire Visit Report: Nerco Minerals Cripple Creek
State of Colorado, Mined Land Reclamation Division. 1992 (April 3). Letter from M.B. Long,
Director, to E.T. Hunter, Nerco Minerals Company. Permit M-81-134: Notice of Board
issuance of Notice of Violation M-92-022 and assessment of civil penalty ($350) for cyanide
spill on February 26.
State of Colorado, Office of the State Engineer, Division of Water Resources. 1991 (July 30).
Memorandum from D.L. Nettles, Water Resources Engineer, to D.I. Hernandez, Mined Land
Reclamation Division. Permit M-81-134, Victor. Mine Amendment: Recommendation against
approval of Victor Mine amendment (Nerco 5/10/91) pending resolution of water rights.
Teller County, Colorado., 1988 (August 22). Letter from R.E. Bergman, Teller County
Commissioners, to G. Tuffino, Vice President, Texasgulf Mining and Materials, Inc. (Letter
citing August 12 cyanide spill and requesting immediate notification in case of future incidents.)
Texasgulf Minerals and Metals, Inc. 1988 (September 19). Letter from T.L. Aragon, Legal
Counsel, to D. Holder, Colorado Mined Land Reclamation Division. Victory Project, MLRD
Permit 86-024: Response to MLRD letter of August 29, 1988, advising Texasgulf of Board
hearing on possible violation (August 12 cyanide spill).
Texasgulf Minerals and Metals, Inc. 1989 (March 16). Letter from T.L. Aragon, Legal Counsel, to
J. Doerfer, Colorado Mined Land Reclamation Division. MLRD Permits 80-244 (Carlton Mill
Pad 2) and 86-024 (Victory Project Pad 4): Water balance information. Subsequently approved
as Victory Project Technical Revision 5 and Carlton Mill Project Technical Revision 4.
Texasgulf Minerals and Metals, Inc. 1989 (April 14). Letter from T.L. Aragon, Legal Counsel, to
J. Doerfer, Colorado Mined Land Reclamation Division. Victory Project, MLRD Permit 86-
024: Copies of internal Texasgulf reports on cyanide spills on April 11 and 12.
Texasgulf Minerals and Metals, Inc. 1989 (May 10). Letter from T.L. Aragon, Legal Counsel, to J.
Doerfer, Colorado Mined Land Reclamation Division. Victory Project, MLRD Permit 86-024:
Topsoil/Growth medium balance information and proposed replacement plan. (Includes MLRD
and Texasgulf correspondence culminating in MLRD's 12/6/89 approval of Technical Revision
for reclamation of the Portland Pit; does not include 8/30/89 Technical Revision application.)
Texasgulf Minerals and Metals, Inc. 1989 (July 24). Internal Texasgulf memorandum from W.S.
Moser to J.S. Burt. Victory Project, Permit 86-024: "De Minimus Solution Spill on Pad #4,
July 23, 1989."
Thompson, T.B. 1992 (February). "Mineral deposits of the Cripple Creek district, Colorado."
Mining Engineering (February 1992), pp. 135-138.
4-81
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Site Visit Report: Nerco Minerals Cripple Creek
APPENDIX 4-A
PERMIT HISTORY OF THE CARLTON MILL HEAP LEACH PADS
(MLRD PERMIT 80-244)
4-82
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Site Visit Report: Nerco Minerals Cripple Creek
Permit History of Carlton Mill Project Heap Leach Pads 1 and 2 (MLRD Permit 86-024)
Date
Event
Description
1980
(application not
obtained
Permit
application/
approval
69.7 acres. Previously .had been conventional flotation mill. Tailings
were disposed in impoundment immediately below mill area. Active
from early 1950s through 1962, then briefly in 1982. Extent of 1980s
operations as conventional mill was not determined.
May 30, 1985
(CC&V
3/12/85; MLRD
5/30/85)
Amendment 1
Add heap leach pad and recovery system. Use Cresson and Gold
Sovereign mine dumps as sources of 150,000 tons of ore for Carlton
Mill leach pad (no. 1) in 1985 season. Crushing to occur at pad.
Seasonal leaching, six months per year. Only preliminary design
presented in amendment application.
Two double-lined pads planned but actually constructed as single
pad: planned sizes were 147,750 and 167,000 ft2 with maximum
slope of 10 percent (requiring cutting and filling, removal of old
tailings and soil); actual size of single pad not determined but
described as "slightly larger." Maintain 20-foot unstacked apron on
liner around heap. Liners not described. Nominal design: four
cells divided by internal (below liner) berms; each to be leached
separately. Pads immediately uphill of existing tailings
impoundment. French drains were installed under pad to lower
water table.
Crush ore to 0.5 - 1 inch, add cement and cyanide agglomeration,
convey to stacker or loader on heap.
Sprinkler application of sodium cyanide solution at 217 (150-250)
gpm: First applied to primary module, then to secondary module,
then conveyed to pregnant pond and recovery. Modules leached for
30-45 day period.
Four ponds: double-lined barren and intermediate working ponds
plus pregnant and backup ponds-liners not described. Each pond to
measure (nominally) 100 x 100 x 12 feet, with 544,000 gallon
capacity. Total capacity sufficient for process solutions and 100-
year/24-hour storm. Area immediately downslope of ponds (upper
end of old tailings impoundment) bermed to serve as emergency
catchment area.
Gold recovery in portable columns in adjacent concrete-lined and
curbed area; then, in Carlton Mill building, pressure caustic
stripping, electrolytic plating onto stainless steel wool, smelting to
dore. Rates not specified.
200-pound cyanide barrels to be triple-rinsed, crushed, landfilled
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Sire Visit Report: Nerco Minerals Cripple Creek
Permit History of Carlton Mill Project Heap Leach Pads 1 and 2 (MLRD Permit 86-024)
Date
Event
Description
March 24, 1986
(CC&V
1/16/86; MLRD
3/24/86; Dames
& Moore 1986)
Amendment 2
Increase permitted area to 116.1 acres by adding more old mine
dumps as sources of ore. Additional $9,700 bond for total of
$75,000.
Add another 150,000 tons to Pad 1.
Construct another heap leach pad (Pad 2) and pregnant pond
immediately downgradient from Pad 1, on top of Tailings Dam No.
1 impoundment. Use Pad 1 pond for barren pond. Use area mine
dumps as source of ore. Crush and agglomerate at dumps or on-
site.
Tailings on which heap to be constructed ranged from 7 to 74 feet
deep. Saturated at depths of 30 feet (under center of impoundment)
to 45 feet (near dam). There was a 12-inch pipe on west abutment
with continuous slow seepage. Consultant recommended plugging
with grout. Not determined if actually plugged.
Heap to reach 100 feet height, four 25-foot angle of repose lifts set
back 25 feet between lifts, for 2H:1V side slope. Total lined pad
320,000 ft2, with 20-foot heap setback. Single 80-mil HOPE liner,
with old tailings to serve as secondary liner. It was anticipated that
the tailings under the heap, and thus the base of the heap, would
settle about three feet near the center of the heap. Pad was to be
sloped to maintain positive drainage. Plans were to add about
250,000 tons of ore per year through 1989. Capacity: "600,000
tons or more."
Pregnant pond: Double-lined, excavated into tailingsliners not
described. Remainder of tailings impoundment below pond (i.e., to
raised dam) described as potential emergency storage, as was Dam 2
impoundment immediately downgradient. Capacity of lined pond
about 2,120,000 gallons plus one foot freeboard. Unlined area in
Dam 1 impoundment provided an additional 827,000 gallon
capacity.
Consultant recommended: place pneumatic piezometers in tailings,
establish survey monuments on pad liner ahead of ore placement,
and slope indicators between heap and pond. Not knoWn if
installed/implemented.
April 20, 1987
(CC&V
4/27/87)
Cyanide spill
Coupling hose for portable carbon column separated and total of 7,500
gallons (500 gpm for 15 minutes) of cyanide solution escaped.
Cyanide concentration was less than 0.5 pounds per ton of solution.
Most (5,500 to 6,500 gallons) were contained in outdoor concrete-lined
and -curbed area, from which solution drained to solution ponds.
About 1,000 to 2,000 gallons overtopped curb and flowed across
unlined surface 300 feet to unlined emergency storage pond, where it
was diluted with 1,500,000 gallons of stored storm water. No solution
reached off-site areas. Cleanup of flowpath not described. Remedies
included regrading and installation of automatic shutoff devices.
4-84
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Site Visit Report: Nerco Minerals Cripple Creek
Permit History of Cariton Mill Project Heap Leach Pads 1 and 2 (MLRD Permit 86-024)
Date
Event
Description
March 26, 1987
(CC&V
2/23/87a;
MLRD 3/23/87)
Technical
Revision 1
1987 plans for Pad 2:
Add an additional 500,000 tons of leach ore to 1986's 462,000 tons.
Stack ore to height of 130 feet or extend lined pad to north to within
20 feet of a ditch between this pad and Pad 1. This would result in
an additional three inches of settling of the pad.
Also add additional water capacity: to use unlined top of tailings
impoundment (on which the pad is constructed) and an additional
3,500,000 gallon unlined emergency pond below the dam of the
tailings impoundment. The latter required improvements to the crest
of the lower tailings impoundment dam (dam 2). In approval,
MLRD required notice if unlined areas were actually used to store
water.
October 8, 1987
(CC&V
11/3/87)
Cyanide spill
Spray header on Pad 2 broke, creating washout on northwest side of
pad. Washed-out toe reached to within three feet of liner edge and
some solution ran off pad. 20-gallon puddle off the liner resulted.
Sampling (no results presented) showed cyanide in the solution but not
the soil. Cyanide was neutralized (no details provided) and followup
sampling showed no detectable cyanide in soils.
November 1987
(CC&V
11/19/87)
Leak in
primary liner
of Pond 4
Noted that cyanide had been detected in the leak detection system of
Pond 4 on an unspecified date during 1986 (?) operating system. The
pond had been removed from operation. After emptying pond, several
holes in primary liner were discovered and repaired. Secondary
(lower) liner was intact. Pond was to be returned to service in 1988.
January 1988
(CC&V
11/20/87,
MLRD 1/25/88)
Technical
Revision 2
Rehabilitate portions of Cariton Mill circuit: receiving, crushing,
surge capacity, grinding, and thickening.
Install new six-stage carbon-in-leach circuit with capacity of 150
tons per day. To use mill for high-grade ore stockpile. To grind to
80 percent -325 mesh.
Slurry a total of 25,000 tons of tailings (about 45 percent solids)
from mill to top of heap leach Pad 1. Excavate and construct (via
berms) an unlined "pond" on the top surface of the pad for tailings
disposal. Decant water to be recycled to mill.
Geotechnical studies indicated that tailings would not filter through
leached ore material in appreciable amounts but fluids would leach
through for collection in existing Pond 4.
No change in reclamation requirements. Fine mill material was
thought to be more amenable to revegetation without topsoil
amendments.
February 1988
(MLRD 2/9/88
and 2/26/88;
CC&V 2/22/88)
Amendment 3
Application for amendment not obtained. References include MLRD
adequacy review and CC&V response.
Expand Pad 2 to 440,820 ft2, with lined "spray apron" of 20 feet
around heap. To leach about 200,000 tons of ore in one 50-foot lift
in the expansion area. Expansion to extend up adjacent hillside,
which required innovative liner-joining techniques.
Added 7.9 acres to permit area, for total of 130 acres.
4-85
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Site Visit Report: Nerco Minerals Cripple Creek
Permit History of Carlton Mill Project Heap Leach Pads 1 and 2 (MLRD Permit 86-024)
Date
July 1988
(MLRD 7/7/88;
CC&V
5/31/88a)
April 1989
(CC&V
3/16/89; MLRD
4/21/89)
June 1990
(Pikes Peak
4/27/90; MLRD
6/22/90)
Event
Technical
Revision 3
Technical
Revision 4
Technical
Revision 5
Description
Redesign of leak detection system for expansion of Pad 2 approved
with Amendment 3. Originally, liner was to be laid on the steep slope
in upper and lower sections, with leak detector drains at toes of both
sections. Redesign led to installation of liner in a single section, thus
eliminating the drain below the upper section. The nature of subgrade
actually encountered (some hard rock, some rocky colluvium) made
original design infeasible. Also, angular cobbles made it necessary to
change from 16-ounce geotextile underlayer (for liner cushion) to a
layer of old tailings.
Water balance information for 1989 operating season. No change in
pond capacity required (existing ponds sufficient for operating
volumes, 100-year/24-hour storm, and some heap desaturation).
Changes to water quality monitoring requirements. Requirements
include sampling of:
Arequa Gulch upstream and downstream of Carlton Mill
Pad 1 French drain
Six "ground-water" monitoring wells in tailings below Pad 2.
Semiannual monitoring of full suite of parameters; monthly for pH and
WAD, free, total CN. Parameters include dissolved, not total, metals.
4-86
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Site Visit Report: Nerco Minerals Cripple Creek
APPENDIX 4-B
PERMIT HISTORY OF THE VICTORY PROJECT (MLRD PERMIT 86-024)
4-87
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Site Visit Report: Nerco Minerals Cripple Creek
Permit History of Victory Project Pads 3 and 4 and Portland Pit (MLRD Permit 86-024)
Date
February 21, 1986
(CC&V 2/21/86)
January 1987
(MLRD 1/12/87)
February 23, 1987
(CC&V 2/23/87b and
5/26/87)
Event
Permit
application
Excess water
Technical
Revisions 2
and 3"
Description
34.5 acre cyanide heap leach operation 0.5 miles north of Victor,
1.5 miles SE of Ironclad/Globe Hill facility. On ridge of Battle
Mountain.
Nearby mine dumps to serve as sources of ore. Seasonal
operation, April through November.
Most of site void of vegetation and covered with old tailings
(from inches to "tens of feet" thick).
One pad: 381,000 square feet, including 20-foot "safety
apron." 1,000,000 ton capacity, 360,000 tons expected during
1986. Less than 10% average slope, < 20% maximum.
Double lined (80-mil HDPE over compacted old tailings). All
pipes six-inch or less PVC.
Heap to be constructed in lifts: 35 feet in 1986, subsequently
10-12 foot lifts to final height of about 100 feet.
Recovery plant: portable carbon columns for adsorption,
with loaded carbon trucked to Carlton Mill for stripping, etc.
Three ponds with total capacity of 4,090,000 gallons,
sufficient for 100 year/24-hour storm plus operating volumes.
500-550 gpm spray rate at 0.004 gpm/ft2. All ponds double-
lined and surrounded by dikes/berms. Construction required
substantial cut and fill. Ponds include:
1,680,000 gallon barren
1,040,000 gallon pregnant
1,775,000 gallon emergency storage pond
598,000 gallon emergency overflow capacity (also lined).
Barbed wire fence around entire area, chain link fence around
ponds.
All upslope run-off diverted around site and unspecified
number of old mine openings sealed.
Required to sample surface water in North Fork of Wilson
Creek semi-annually.
Reclamation: detoxify heap until effluent reaches unspecified
"acceptable quality", contour slopes to < 2H:1V. Backfill
and re vegetate ponds but not heap.
$21,500 bond.
500,000 gallons of water hauled from Victory emergency pond to
Carlton Mill Pond 1.
Enlarge pad for 1987 operations.
416,000 tons had been stacked in 1986, 430,000 more tons to
be added in 1987, in 25-foot lifts. Pad area covered 291,980
ft2.
Increase pond capacity by adding 4-foot lined berm around
ponds: to add 2,392,000 gallons additional storage, to a total
of 7,485,000 gallons. Ponds covered 79,980 ft2.
4-88
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Site Visit Report: Nerco Minerals Cripple Creek
Permit History of Victory Project Pads 3 and 4 and Portland Pit (MLRD Permit 86-024)
Date
Event
Description
July 1987
(CC&V 7/17/87 and
12/8/87; Dames &
Moore 3/16/89)
Amendments 1
and 3
Add 49.83 acres to permit (including 21.27 acres from permit
86-009) for new Pad 4. Much of area covered with old
tailings and waste, rock. Constructed hi 1988.
New 15 acre heap leach pad (Pad 4 or Portland Pad), to be
constructed in four subcells. Partially built on top of waste
rock dumps, including new rock from Portland pit (see
amendment 2 below). Double-lined pad (60-mil HDPE,
granular tailings with 3-inch pipes as drainage layer, and 80-
mil HDPE) constructed on base of compacted tailings. Pad
covers 660,000 ft2, capacity of about 1,825,000 tons.
Ore from old dumps in area and new pit (see amendment 2
below)
Part of.pad drains to Pad 3 ponds, part to three new ponds:
1,935,000 gallon pregnant, 491,500 gallon barren, 1,616,000
gallon emergency overflow ponds. All have double 60-mil
liners with geotextile leak detection system. Later described
as having 6,300,000 gallon capacity (Texasgulf 3/16/89),
presumably reflecting expansions for which documents not
obtained for this report. All six ponds for Pads 3 and 4
connected by pipes for gravity/pumping flows.
12 old shafts in construction area filled with gravel and
compacted. One large shaft remained between pad and ponds.
Reclamation: similar to Pad 3.
672,000 tons placed on Pad 4 in 1988; one lift 8-30 feet high,
averaging 20-25 feet (Texasgulf 3/16/89).
August 1987
(CC&V 8/12/87)
Amendment 2
Add 28.18 acres to permit (including 9.94 from another permit).
Construct open pit mine, the Portland Pit, adjacent to and
downhill of Pad 4.
Expected to reach 500 feet (east to west) by 1,400 feet (north
to south) by 240 feet deep. Waste:ore ratio of about 2.5:1
predicted 500,000 tons ore and 1,300,000 to 1,500,000 tons
waste rock. About 600,000 tons waste rock used for fill in
Pad 4 construction.
Waste rock at angle of repose on hillside. Some minor
smooth grading anticipated for reclamation.
Reclamation: Safety/warning bench about 15 feet below top;
remainder benched as recommended by MSHA. Re-soil and
vegetate benches and pit floor if sufficient topsoil or other
medium is salvaged.
December 1987
(CC&V 12/18/87)
Solution in
leak detection
system, Pad 3
On December 5, CC&V noted solutions flowing out of leak
detection pipe on Pad 3: analyses showed high (but unspecified)
cyanide, pH, and gold. On December 6, shut down spray on
that portion of heap; within 24 hours, flow had slowed
significantly. Notified MLRD on December 7. CC&V attributed
flow to tear in primary liner along seam where expansion joined
original construction; "probably" the result of late-season slough
(otherwise undescribed). CC&V planned to leave this area
unsprayed, then try to find and fix leak. CC&V noted a "remote
possibility" of permanently shutting down this part of heap. No
further information obtained.
4-89
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Sire Visit Report: Nerco Minerals Cripple Creek
Permit History of Victory Project Pads 3 and 4 and Portland Pit (MLRD Permit 86-024)
Date
Event
Description
May 31, 1988
(CC&V 5/31/88)
Technical
Revision 4
Construct haulage road across bench on face of Pad 3 to provide
easier access to Pad 4.
July 5, 1988
(CC&V 7/21/88)
Damage to
pads and ponds
Errant blast in Portland Pit: fly rock punctured primary liners in
Pads 3 and 4 and in five of the six solution ponds. All being
repaired. Attributed to use of "extra powder" in wet blastholes.
August 12, 1988
(MLRD 8/16/88,
9/22/88b)
Cyanide spill
1,500 to 2,000 gallons of barren solution spilled from pipe
ruptured by loader. Flow followed gully off-site for 300 yards
before entering abandoned mine shaft. Led to NOV M-88-015.
Described in chapter 4 text.
March 16, 1989
(Texasgulf 3/16/89)
Technical
Revision 5
Water balance information for 1989 operations: Total storage
volume needed for 100-year/24-hour storm containment plus
operating volumes calculated at 13,064,000 gallons, compared to
13,400,000 gallons actual capacity in Pads 3 and 4 ponds.
April 11, 1989
(Texasgulf 4/14/89)
Cyanide spill
Cracked pipe (the result of freezing) spilled up to 2,880 gallons
(3 gpm for 16 hours) of pregnant solution. Solution contained
0.65 pounds sodium cyanide per ton of solution, so up to 7.75
pounds of NaCN were involved. Most solution was contained by
the Pad 4 pond liner system but some escaped into pond
embankment material. Area treated with calcium hypochlorite.
April 12, 1989
(Texasgulf 4/14/89)
Cyanide spill
Hose emptying barren solution into mix tank fell out of tank and
landed across the curb that surrounded the cement pad near heap
leach Pad 3. About 3,000 gallons of barren solution (0.45
pounds cyanide per ton of solution, pH about 10.2) ran across the
ground for 50 feet, where the flow entered the lined Pad 3
solution ponds.
July 23, 1989
(Texasgulf 6/24/89)
Cyanide spill
Some unspecified cause resulted in flow from a "blown 1/2-inch
dripper line" leaving the pad (via an old access ramp) and
trickling 40 to 50 yards down the road to the east. An estimated
240 gallons containing 0.8 pounds cyanide escaped. Five pounds
of calcium hypochlorite in a water solution was applied to the
flowpath.
September 11/1989
(Nerco 8/22/90)
Change in
name
Nerco changed name of Texasgulf Minerals and Metals to Pike's
Peak Mining Company (changed to "Pikes Peak" in 1990). It
should be rioted that Nerco's 100 percent purchase of Texasgulf
from ELF Aquitane was not effective until August 31, 1990,
nearly a year after Nerco changed the name of Texasgulf.
May - December
1989
(Texasgulf 5/10/89)
Technical
Revision (6?)
Reclamation plan for Portland Pit. Texasgulf reported 30,000
yd3 of old tailings and topsoil had been salvaged and stored. It
was proposed to place this on waste dump, areas of process
ponds, pit benches and floor, and other disturbed areas prior to
revegetation. No revegetation of Pads 3 and 4 heaps planned.
(Note: Final plans not obtained.)
January 9, 1990
(CC&V 2/12/90)
Cyanide spill
Ice buildup in ditch around a Pad 4 pond blocked ditch flow and
solution flowed onto and over surrounding berm. Flow did not
reach bottom of berm. About 500 gallons (1.04 pounds sodium
cyanide, pH of 9.6) was involved. Neutralized with calcium
hypochlorite; intended to raise berm by 2-3 feet.
4-90
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Site Visit.Report: Nerco Minerals Cripple Creek
Permit History of Victory Project Pads 3 and 4 and Portland Pit (MLRD Permit 86-024)
Date
April 27, 1990
(Pikes Peak Mining
Company 4/27/90)
November 5, 1990
(CC&V 11/5/90)
Event
Technical
Revision 9"
Cyanide spill
Description
Improve water quality monitoring. Sample .Wilson Creek
upstream and downstream of Victory Project: semi-annual
monitoring of full suite of parameters (Free CN, pH, nitrate,
nitrite, and metals). Included data from 1987, 1988, and 1989.
100 gallons containing O.S2 pounds CN per ton of solution "got
off the edge of the pad liner" of Pad 4. No other details on
cause or extent of spill were provided. -The spill was neutralized
with two pounds of hypochlorite.
* Technical revision one not obtained. Of technical revisions 6, 7, and 8, only one was obtained.
4-91
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Site Visit Report: Nerco Minerals Cripple Creek
APPENDIX 4-C
COMMENTS SUBMITTED BY NERCO MINERALS COMPANY
ON DRAFT SITE VISIT REPORT
The letter reproduced in this appendix accompanied a copy of the draft site visit report dn which
. Nerco Minerals Company had made comments and corrections. A copy of the marked-up draft is not
reproduced here for brevity's sake. In general, Nerco's comments were clarifying in nature,
providing information that the draft report indicated had not been obtained during the site visit or
correcting minor factual errors in the draft. EPA's response to Nerco's comments are provided in
Appendix 4-D
4-92
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Site Visit Report: Nerco Minerals Cripple Creek
[Comments not reproduced for this
electronic version. Copies may be
obtained from U.S. EPA, Office of
Solid Wastes, Special Waste Branch.]
4-93
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Site Visit Report: Nerco Minerals Cripple Creek
APPENDIX 4-D
EPA RESPONSE TO COMMENTS SUBMITTED BY
NERCO MINERALS COMPANY
ON DRAFT SITE VISIT REPORT
4-94
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Site. Visit Report: Nerco Minerals Cripple Creek
EPA Response to Comments Submitted by
Nerco Minerals Company
on Draft Site Visit Report
EPA has revised the report to incorporate all of the comments and suggestions made by Nerco
Minerals Company. In some cases, EPA made minor changes to wording suggested by Nerco in
order to attribute the changes to Nerco or to enhance clarity.
4-95
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Site Visit Report: Newmont Gold Company Rain Facility
MINE SITE VISIT:
NEWMONT GOLD COMPANY
RAIN FACILITY
U.S. Environmental Protection Agency
Office of Solid Waste
401 M Street SW
Washington, DC 20460
-------
Site Visit Report: Newmont Gold Company Rain Facility
5.0 SITE VISIT REPORT: NEWMONT GOLD RAIN
5.1 INTRODUCTION
5.1.1 Background
The U.S. Environmental Protection Agency (EPA) is assisting states to improve their mining
programs. As part of this ongoing effort, EPA is gathering data related to waste generation and
management practices by conducting site visits to mine sites. As one of several site visits, EPA
visited the Newmont Gold Company Rain facility near Carlin, Nevada, on August 20 and 21, 1991.
Sites to be visited were selected by EPA to represent both an array of mining industry sectors and
different regional geographies. All site visits have been conducted pursuant to RCRA Sections 3001
and 3007 information collection authorities. Although Newmont Gold Company disputes EPA's
authority to proceed under those sections of RCRA, Newmont Gold cooperated with EPA in
connection with the Rain site visit. When sites have been on Federal land, EPA has invited
representatives of the land management agencies [Forest Service/Bureau of Land Management
(BLM)]. State agency representatives and EPA regional personnel have also been invited to
participate in each site visit.
For each site, EPA has collected information using a three-step approach: (1) contacting the facility
by telephone to get initial information, (2) contacting State regulatory agencies by telephone to get
further information, and (3) conducting the actual site visit. Information collected prior to the site
visit is reviewed during the visit to ensure accuracy.
In preparing this report, EPA collected information from the State of Nevada and Newmont Gold
Company. The Nevada Department of Environmental Protection (NDEP) provided information
relating to the Rain facility's Water Pollution Control Permit and associated records including the
Final Environmental Assessment (Newmont Services, 1987b), design reports, correspondence, and
informal communication with NDEP personnel. EPA also obtained information from telephone
interviews with Newmont and NDEP personnel. The following individuals participated in the
Newmont Rain facility site visit:
Newmont Gold Company
Dave Baker, Vice President, Environmental Affairs 303-837-5885
Eric Hamer, Vice President, Newmont Nevada Operations 702-778-4252
Steve Winkelmann, General Superintendent 702-778-4526
Pat Lorello, Environmental Compliance for Nevada Operations 702-778-4139-
John Mudge, Mill Superintendent 702-778-4577
Kurt Criss, Senior Mine Engineer 702-778-4885
5-1
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Site Visit Report: Newmont Gold Company Rain Facility
Mark Raffrnan, Attorney (Shea & Gardner) 202-775-3017
John Jory, Geologist 702-778-4507
State of Nevada
<*
Doug Zimmerman, Division of Environmental Protection 703-687-4670
Dennis Anderson, Department of Mines 702-687-5050
Rory Lamp, Department of Wildlife 702-738-5332
Bureau of Land Management
Nick Rieger, Physical Scientist 702-753-0200
U.S. EPA/Office of Solid Waste
Steve Hoffman, Chief, Mine Waste Section 703-308-8413
Patti Whiting, Environmental Protection Specialist 703-308-8421
Science Applications International Corporation
Jack Mozingo, Environmental Scientist 703-734-2513
Joseph Rissing, Geologist 703-734-4366
Participants in the site visit were provided an opportunity to comment on a draft of this report.
Comments made by Newmont Gold Company are presented in Appendix 5-E. EPA responses to
comments by Newmont are in Appendix 5-F.
5.1.2 General Description
The Rain facility, owned and operated by Newmont Gold Company, is located approximately 9 miles
southeast of Carlin in Elko County, Nevada (see Figures 5-1 and 5-2). Access to the facility from
Carlin is by Ridge Road, which was widened and straightened by Newmont during the development
of the Rain facility. The road is approximately 14 miles long and crosses BLM lands that are
allocated for grazing. This road is well maintained and is bermed along much of its length to control
run-off. Diversions and culverts in drainageways vrrve to minimize run-on. Fugitive dust is
controlled by watering with added surfactant. A power line to the facility generally follows the road.
The facility is a mining-milling-leaching operation for heneficiating disseminated gold ore. Ore and
waste rock are mined from an open pit. Waste rock is material that does not contain sufficient gold
values to justify milling or leaching, and is removed to access the ore. According to the final
environmental assessment (Newmont Services, 1987b) 47 6 million tons (all tonnage figures in short
tons) of material were planned to be removed from the pit from 1988 project startup through the
projected 8-year life span of the mine. Of the totaJ projected volume, approximately 10.1 million
tons was expected to be ore grade and 37.5 million torn »we rock. As of October 1990, these
figures had been revised: projected waste rock tonnafc »a* estimated to be 41.4 million tons by the
5-2
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Site Visit Report: Nevmont Gold Company Rain Facility
California
Arizona
Figure 5-1. Site Location Map
(Source: SRK 1990)
5-3
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Site Visit Report: Newmont Gold Company Rain Facility
TAILING
IMPOUNDMENT
O Monitoring ir«lln ICY-SB. VW-3
Bait French Drain: KFD |
D We«t French Drain: 1TD
D Pref. Pond Pump: PPP
D Under Dralnag* Cellcotion Pond:
D Undtr Drainag ₯aUr. UT
D Seepafo Pond: CP
Upilr«am Trtndh Drain: VTD
Downitroam Trench Drain: DTD
i* itoo*
C*KUV latural
Figure 5-2. Location of Rain Facilities
(Source: Newmont Gold Company)
5-4
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Site Visit Report: Newmont Gold Company Rain Facility
end of 1990, and 62.5 million tons during the life of the mine, at a stripping ratio of 3.55:1. Of the
ore removed from the mine, over forty percent is milled and beneficiated by the carbon-in-leach
method at a current rate of about 840,000 tons per year (TPY). The remaining ore (about 1,000,000
tons per year) is leached using a modified heap method referred to as a valley leach (SRK, 1990).
r
The facility is located on approximately 627 acres covering parts of four Sections (see Figure 5-2).
During the site visit, Newmont explained the distribution of surface and mineral rights to the land
held by the BLM and private parties as follows: Newmont Gold Company holds the surface rights in
T32N, R53E, Section 33, and T31N, R53E, Section 4; a private party holds the mineral rights to
these Sections. These Sections are the current location of the pit, leach pad, and tailings
impoundment, and a portion of the waste rock dump. Newmont Gold Company holds the mineral
rights for T32N, R53E, Section 34; BLM holds the surface rights to this Section. An ore stockpile
and the remainder of the waste rock dump are located in this Section. Private parties hold both
surface and mineral claims to T31N, R53E, Section 3; most of the mill facility is located in the
northwest quarter of this Section.
5.1.3 Environmental Setting
The Rain facility is located near the northern end of the Great Basin Physiographic Province, in the
Pinon Mountain Range, part of the area known as the Carlin Trend. It is 90 miles east of the Central
Nevada Seismic Zone. The facility is at an elevation of approximately 6,600 feet above sea level
(asl) between Rain Peak (elevation 7,403 feet asl) on the west and Snow Peak (7,128 feet asl) on the
east. The mine pit is situated on the east flank of Rain Peak, the east side is the lower elevation at
6,575 feet, the west side is at 7,000 feet. The mill complex and ore stockpiles are located in the
saddle area between the peaks. The waste rock dump is located on the north side of the saddle above
the Emigrant Springs drainage. The tailings impoundment is on the southwest side of the saddle
below the mill in the ephemeral headwaters of Ferdelford Creek (Figure 5-2).
Soils in the project area are made up of both aridisols and mollisols, typically having accumulations
of clay and/or calcium carbonate below the surface. Parent materials include andesite and rhyolite
from volcanic sources and shale, sandstone, and conglomerate from sedimentary sources. Native
vegetation consists of sagebrush, cheatgrass, and bluegrass. Cattle grazing is the primary land use in
the area; during the site visit, several cattle were observed along the access road and a cattle trough
was observed in the Emigrant Springs drainage between the waste rock dump and Emigrant Springs.
5.1.3.1 Climate
The Rain facility, like all of Nevada, is dominated by continental air masses. High solar energy input
and no consistent moisture source result in a dry. warm climate. Precipitation events are typically in
the form of thunderstorms in warmer months and smm squalls during the winter. December is
typically the wettest month. Annual precipitation at the sue averages 12 inches. The average annual
5-5
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Site Visit Report: Newmont Gold Company Rain Facility
snow fall is estimated to be 55 inches, with most snowfall occurring between October and May. July
is the warmest month with an average high temperature of 84.6°F; December is the coldest with an
average of 18.2°F. There are approximately 95 frost-free days at the site. Prevailing winds are from
the southwest, averaging six miles per hour (mph). However, local relief influences air flow in the
project area (SRK, 1990, and Newmont Services, 1987b).
5.1.3.2 Geology
Sediment-hosted gold of the Carlin trend is characterized by gold in the micron or less size range
deposited in carbonaceous, thin-bedded silty limestones or limy siltstones. The suite of elements
usually includes arsenic, antimony, mercury, thallium, and molybdenum. Barite is a common gangue
mineral. Silicification in the form of jasperoid is used as a major indicator during exploration.
According to the environmental assessment, rocks in the project area are composed of the Upper
Devonian and Lower Mississippian age sediments (345 million years before present). Most of the site
lies on Chainman Shale (Lower Mississippian) and, to a lesser degree, the Webb Formation (Lower
Mississippian), and the Devils Gate Limestone (Upper Devonian) . The Chainman Shale is
composed of a variety of rock types including: grey to black shale, quartz and chert-rich sandstone,
conglomerate lenses, thin limestone, calcareous sandstone beds, and pebbly mudstone. The Webb
Formation consists of grey clay-rich siltstones and shales with interbedded sandstone. The Chainman
Shale and Webb Formation unconformably overlie part of the Devil's Gate Limestone, characterized
by medium to thick-bedded light to dark grey limestone. This is the material now being encountered
at the base of the pit on the east end (see Figure 5-3) (Bonham, 1988; Newmont Services, 1987b; and
SRK, 1990).
Structural control that led to the deposition of precious and other metals at the Rain site is similar to
the processes found throughout the Carlin trend. A high angle reverse fault crosses the Rain pit on
roughly a northwest strike. The fault is traceable for 1,800 feet along the surface and is up to 200
feet wide. It is this fault that is believed to be the paleo-conduit for hydrothermal fluids to migrate
toward the surface. The Webb Formation hosts the minerals deposited by these migrating fluids.
Joints in the Webb Formation intersect the fault and are partially responsible for the enrichment of the
ore zone. Silica, gold, silver, mercury, arsenic, and a host of other elements filled voids and
replaced material leached by the migrating acidic solutions. Gold occurs predominantly as micron-
size particles disseminated in the host rock matrix. Rocks of the Webb formation near the surface are
oxidized; consequently, the pyrite has been converted to hematite and/or limonite indicated by
liesegang banding. Below the oxidized zone, rocks of the Webb Formation contain abundant carbon
and pyrite. Most of the gold associated with the Rain ore zone is located near the Rain fault in
oxidized and hematite-stained mudstones and siltstones of the Webb Formation. The vertical extent of
gold mineralization ranges from the surface down to the unconformable contact with the Devil's Gate
limestone. Minor faults that intersect the main fault, possibly in more permeable material, allowed
the fluids to migrate southwest of the main fault and therefore expanded the ore zone. Figure 5-4
shows a cross-section of the Rain pit (A - A') identified in Figure 5-3 (SRK, 1990).
5-6
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Site Visit Report: Newmont Gold Company Rain Facility
RAIN PIT
\ SEC.
North
(Source: SRK 1990)
0 Feet 400
0 Meters 1500
Scale
Figure 5-3. Pit Geology
5-7
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Site Visit Report: Newnwnt Gold Company Rain Facility
EXPLANATION
CONTACT
eowo
SUCA
CAftlON
6800*
600-
S400'
fi:oo*
6000*
A.'
6MO-
6600
6400
CBOO*
EXPLANATION
CONTACT
Figure 5-4. Cross Section of Rain Pit, Section 1800SE
(Source: SRK 1990)
5-8
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Site Visit Report: Newmont Gold Company Rain Facility
Six types of mineralization are recognized at the Rain mine: siliceous, siliceous/baritic, baritic,
carbonaceous, argillaceous, and calcareous. Siliceous recks contain greater than 40 percent quartz
and less than 30 percent barite. Siliceous/baritic rocks contain 30 to 40 percent barite. Baritic rocks
contain greater than 40 percent barite. Carbonaceous rocks contain high (unspecified) total organic
carbon and greater than 0.5 percent pyrite (Figure 5-4). Argillaceous rocks have a clay content
greater than 40 percent. Calcareous rocks are mostly carbonates, composed of calcite (SRK, 1990).
Most of the ore-grade material is taken from the oxidized sediments of the Webb Formation, proximal
to the Rain fault. Ore taken from this area contains siliceous, siliceous/baritic, baritic, and
argillaceous mineralization. Gold concentrations of this material range from 0.01 to 0.150 ounces of
gold per ton of rock. It is expected that the carbonaceous material contains gold values as indicated
by Figure 5-4 (SRK, 1990). According to Newmont, sulfide-bearing rock does not contain gold in
sufficient quantity to be economically recoverable.
Of the 62.5 million tons of waste rock expected to be generated by the mine, 77.8 percent is expected
to be mostly oxidized mixed sedimentary material of the Webb Formation (some of which will contain
sulfide mineralization); 15.4 percent is expected to be carbonaceous and potentially sulfidic; 4.3
percent is expected to be limestone of the Devil's Gate Formation; and 2.5 percent will be alluvium
from surface deposits (SRK, 1990).
5.1.3.3 Hydrology
The Rain facility sits on the drainage divide separating two basins. Seasonal surface water in the
valley where the pit, mill facility, and tailings impoundment are located drains to the west into the
ephemeral headwater drainage of Ferdelford Creek. Ferdelford Creek becomes a perennial stream
four miles below the facility, and it runs for ten miles before entering Pine Creek. From this point,
Pine Creek flows northwest and joins the Humboldt River six miles further downstream. Surface
water on the north side of the saddle between the two peaks, where the waste rock dump is located,
drains predominantly eastward in an ephemeral drainage toward Dixie Flats. Emigrant Springs
(elevation 6,340 feet; about 900 feet from the toe of the waste rock dump) feeds the headwaters of
this drainage, which joins Dixie Creek. Dixie Creek, a perennial stream, flows six miles north to
join the South Fork of the Humboldt River. The site visit team also observed standing water
immediately below (10 to 20 feet) the toe of the waste rock dump that appeared to be a spring but
may have been part of the acid mine drainage collection system.
Baseline data that predate the Rain facility showed that waters of both Ferdelford and Dixie Creek
have high pH, bicarbonate concentration, total dissolved solids, and conductivity. According to the
environmental assessment, sulfate concentrations in Ferdelford Creek were three to four times higher
than Dixie Creek, but decreased at lower elevation. Metals were generally low in Ferdelford Creek
with the occasional exception of iron, aluminum, and arsenic. Arsenic, iron, and manganese were
present in most samples taken from Dixie Creek (Newmont Services, 1987b).
5-9
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Site Visit Report: Newmont Gold Company Rain Facility
Ground-water resources at and near the site have been described as limited. Shallow, perched water
exists and discharges as perennial or ephemeral springs,'such as Emigrant Spring. These discharges
occur where alluvial material encounter impervious clays or silts. The shallow ground water is
apparently recharged by local precipitation and snow melt and is not considered to be connected to the
regional ground water. Deeper ground-water sources exist 350 feet or more below the surface and
have been found to produce limited water volumes [maximum of 80 gallons per minute (gpm)].
Current mining in the pit has reached a depth of 460 feet below grade, to an elevation of 6,440 feet
asl. Exploration drilling has encountered limited quantities of perched ground water between 6,400
and 6,300 feet. Newmont reports that the actual ground water elevation is between 6,100 and 6,160
feet and the projected pit bottom is 6,240 to 6,220 feet; thus, the final pit bottom should be about 100
feet above ground water. Because of the limited access to ground water, the Rain operation draws its
water from wells (100 gpm annual average) in Dixie Flats and pumps it six miles to the mill (SRK,
1990).
5-10
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Site Visit Report: Newmont Gold Company Rain Facility
5.2 FACILITY OPERATIONS
The Rain mine and mill were built between 1987 and 1988. Construction of the tailings dam began
in October of 1987. Construction of the crusher foundation, leach pad, access road, and the solution
handling system, carbon circuits, and water supply system was completed in April of 1988.
According to the FEA, a work force from approximately 40 to as many as 150 people was estimated
to be needed during construction, and 132 during normal operations. At the time of the site visit,. 160
people were employed at the facility. The first gold production began on July 2, 1988 (Newmont
Services, 1987b).
A Newmont Exploration Limited team is examining deposits west and east of the current pit in search
of additional reserves. Ore resources in the immediate facility area (e.g., below the leach pad and
under Rain peak) and on adjacent land may add to existing reserves 'and extend the life of the mine
and mill. During the site visit, Newmont personnel noted the possibility of future underground
mining to extract ore reserves below Rain Peak.
Several changes to the facility design described in the environmental assessment have occurred since
the Rain facility began operation. The estimate of the volume of waste rock to be removed from the
pit has increased from 37.5 to 62.5 million tons (Newmont Services, 1987b; and SRK, 1990).
Original plans showed beneficiation continuing through electrowinning, at which point the steel wool
cathode containing the gold would be sent to Newmont's Gold Quarry facility for refining (FEA,
1987). The primary operational difference between design plans in the environmental assessment and
the "as built" facility is that beneficiation at the Rain facility ends when the carbon is loaded with
gold. The loaded carbon is transported in a specially designed truck to the AARL/ZADRA facility at
Gold Quarry (north of Carlin) for further beneficiation.
The total area of disturbance resulting from construction of the mine and mill is approximately 627
acres; widening of the existing Ridge Road for access disturbed a total of 43 acres. In early 1990..
the estimate of the volume of material to be removed from the pit was 80.2 million tons (Knight
Piesold, 1990). Of this, 6.7 million tons was considered to be mill grade ore, 11 million tons to he-
heap leach ore. Based on these figures the stripping ratio was about 3.55:1 (3.55 tons of waste rock
must be removed to recover one ton of ore). At the time of the site visit, the stripping ratio was
reported to be slightly lower, about 3.44:1.
Annual production of ore through the mill and leach pad is approximately 1.84 million tons. RouiihK
one million tons are heap leached, and the mill processes about 0.84 million tons annually. Ore
grades for heap leaching are 0.01 to 0.05 ounces of gold per ton of ore. Mill grade material has j
gold concentration of more than 0.05 ounces of gold per ton of ore. In 1988, the Rain facility
produced approximately 115,000 ounces of gold. Heap leaching accounted for 13,100 ounces, wtnu
the mill produced 101,500 ounces. Material containing less than 0.01 ounces of gold per ton ot r v k
is considered waste and disposed of in the waste rock dump. Individual flow charts showing !!<» *
5-11
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Site Visit Report: Newmont Gold Company Rain Facility
ore and solution at the Rain mine, mill, heap leach, and tailings process, were provided by Newmont
after the site visit and are presented in Appendix 5-A (Newmont Gold Company, 1991bj. A detailed
description and flow chart (Figure 5-5) of the Rain operation is provided below.
During the visit, EPA reviewed Newmont's storage and handling methods for materials onsite.
Support materials such as lubricating and hydraulic oils, truck fuel, and water are stored in tanks
onsite; dry goods such as cyanide, cement, and lime are stored in large bins or bags, depending on
the material. There is a 500-gallon tank for emergency generator fuel, a 30,000-gallon tank for truck
fuel, a 6,000- gallon hydraulic oil storage tank, a 10,000-galIon waste oil tank, and a 6,000-gallon
antifreeze tank. There are no underground storage tanks onsite. Sewage is piped to a treatment
lagoon below the mill facility; effluent enters the tailings pipeline at about one gpm. Cyanide
briquettes are stored in bins in a fenced area before use in the mill. Cement and lime are stored in
60- and 45-ton bins, respectively, in the crushing circuit. Drums of surfactants, antiscalant bags, and
other goods are located near the points of use onsite. Magnesium chloride solution is stored in a tank
where it is mixed with water and applied to the access road and other areas to control dust.
Ammonium nitrate and fuel oil used during blasting is stored near the waste rock dump (away from
most activity) and mixed onsite as needed.
Three wells located east of the facility in Dixie Flats can provide up to 1,200 gpm of fresh water.
The water is piped 5.93 miles to the mill site in a 14-inch iron pipe buried four feet below ground.
Two booster stations are used to pump the water upslope to the mill site. Two water tanks on the hill
above the mill buildings store fresh water for the facility. A 15,000-gallon booster tank feeds a
200,000-gallon process, potable, and fire water tank. Newmont estimates that actual water
consumption averages about 100 gpm on an annual basis; during dry months, consumption may reach
600 gpm.
5.2.1 Mining Operations
An open pit mine is used to remove ore and waste rock at Rain. The bottom of the pit is at 6,440
feet above sea level and is expected to reach 6,240 feet. The top of the pit is approximately 300 feet
wide and 800 feet across and covers about 100 acres of the original ground surface. The pit is
oriented northwest to southeast in alignment with the Rain fault. Access is by ramps entering from
the east side; the pit is closed on the north, west, and south sides. The highwall on the west side
rises approximately 600 feet from the bottom of the pit.
x
As the pit is extended downward, working benches are used to access the rock surface for drilling and
blasting. Separate safety benches are left in the excavated wall to provide a catchment for localized
pit slope failures. The pit is excavated in 20-foot working benches. Prior to blasting, drill hole
cuttings (dry) are sampled for assaying and ore grading. The grade determines whether material is
waste rock, leach ore, or mill ore. Visual observation determines if waste rock is sulfidic and must
be handled separately. (Newmont reports it has undertaken a large-scale testing program to correlate
5-12
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Milling Ore
Stockpile
Heap Leach yv
Stockpile/ \^-
Emergency Mill
Ore Stockpile
8.000 lota
Classifier
IFeed Hopper
Hetrp Leach Crushed Ore Stockpile
Mill Fine Ore Stockpile.
3.000 ions
Rod Mill rf BallMill
R»e Stage Carton Columns
(2,000 gallons)
And icak
and Fresh water
Barren
Solution
Makeop
Loaded Carbon
to Mill W
Reactivated
Carbon from
Mill*?
>' Six Stage Cuban in Leach NaCN
(190,000 gallons)
Sewage
Waslcwater
Six Stage Cuban in Palp
(50.000 gallons)
50.000 gallon
Surge Tank
HWIlttltr.fAK
I
Figure 5-5. Rain Facility Flow Chart
(Source Newmont Gold Company)
-------
Site Visit Report: Newmont Gold Company Rain Facility
visual classification of waste rock with the results of actual laboratory tests. As noted in section
5.3.2, Newmont samples waste rock for various parameters and for acid generation potential on a
quarterly basis.)
After blasting, ore is loaded by front end loaders into 85- and 100-ton haul trucks and transported to
either the waste rock dump or leach and mill ore stockpiles, as appropriate. As of 1990, estimates
were that during the life of the mine, 80.2 million tons of rock would be removed from the pit. Of
this, 6.7 million tons were projected to be mill grade, 11 million tons leach grade ore, and the
balance of 62.5 million tons waste rock.
According to information presented during the site visit, an average of 35,000 tons of material is
being removed from the mine each day. Of this, 5,500 tons is ore grade, 29,500 tons is waste. This
rate may reach 7,000 and 40,000 tons per day, respectively (Newmont Gold Company, 1990d,
1991b). Ore material is separated based on grade and carried by 100-ton haul trucks to the leach or
mill ore stockpiles. Of the 5,500 tons of ore mined each day, 3,150 tons is leach grade and 2,350 is
mill grade. Waste rock removed from the pit is transported by 100-ton Wabco haul trucks to the
waste rock dump for disposal. Mineral characteristics of the rock and disposal methods are discussed
in Section 5.3.
The Rain facility employs unlined ore stockpiles. The stockpile for leach ore is referred to as the
"primary" stockpile and typically contains about 250,000 tons; the mill ore stockpile is referred to as
the "secondary" stockpile and typically contains about 50,000 tons. In some instances, leach ore may
be carried directly from the pit or stockpile to the leach pad and not be sent through the jaw crusher.
This material is referred to as run-of-mine ore. However, most of the leach ore is carried by truck to
a stockpile located near the jaw crusher. Similarly, mill grade ore is carried to a stockpile adjacent to
the leach ore stock. These piles near the crusher typically contain 30,000 tons of each ore, separated
by a line of posts and old truck tires.
Prior to crushing, a front end loader selects mill or leach grade ore from the stockpiles, based on null
capacity and demand at the time. The primary jaw crusher is 36 by 48 inches, and can process 450
tons per hour to less than 6 inches in diameter. A slewing and luffing conveyor system is pivoted.
depending on which ore type is being crushed. Mill grade ore is conveyed to the secondary crush mi:
circuit; leach ore is fed from the conveyor to a pile located between the primary and secondary
crushers.
Leach grade ore receives only primary crushing and agglomeration before being transported to the
heap. Following crushing, about eight pounds of cement is added per ton of ore from a 60-ton
storage bin to agglomerate the fine particles. Water is added through V-Jet sprays at a rate of ah«>ui
10 gpm to begin cement agglomeration. Leach grade ore is stockpiled on the ground by the
5-14
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Site Visit Report: Newmont Gold Company Rain Facility
conveyor, away from subsequent crushing facilities, to be trucked to the heap. The volume in this
stockpile varies.
When mill grade ore is crushed, the slewing and luffing conveyor is pivoted to a position above an
ore bin that feeds the secondary crushing system. This system consists of a 5-by-16-foot Simplicity
double deck screen and a 5.5-foot Nordberg cone crusher. Oversized material (greater than 3/4
inches) from the screen is passed to the crusher, while .undersized ore falls directly to a conveyor belt.
The cone crusher reduces the particle size of ore received from the primary crusher to less than 3/4
inches. The product from the screen and cone crusher is transported by conveyor to the 3,000-ton
mill stockpile prior to entering the mill on a second conveyor. An emergency mill stockpile of 8,000
tons is maintained in the event the crusher circuit fails. To control pH, pebble lime is metered onto
the mill feed conveyer from a 45-ton capacity bin at an average rate, of 1.7 pounds per ton.
Dust generated while handling the ore during crushing and transport is controlled by fogging type
spray nozzles. Water and a sodium and calcium stearate surfactant (at a total application rate of 600
cc/minute, of which 20 cc are surfactant) are applied where crushing and grinding take place, when
cement or lime are added to the ore on the conveyor belt, and where ore is transferred from one
conveyor belt to another. V-Jet sprays, as noted above, are used for agglomeration. Baghouses are
used to capture dust emitted during loading of the cement and lime storage bins; baghouse material is
recycled back to the respective bins.
5.2.2 Mill Operation
Ore is fed by conveyor into an Allis-Chalmers 400-horsepower rod mill at an average rate of 96 tons
per hour, along with sufficient mill solution to make a slurry of 68 percent solids. Mill water supply
is made up in a tank by adding reclaim water from the tailings impoundment, water treatments such
as antiscalants (24 cc/min of polymaleic acid), and fresh water (as necessary), and is distributed
throughout the mill. Newmont is required to sample reclaim water on a quarterly basis, and mill
water supply is also sampled; recent analytical results for reclaim and mill water are presented in
Tables 5-1 and 5-2, respectively.
Mill solution is circulated at approximately 600 gpm, most of which is recycled from the tailings
impoundment (Table 5-1). Fresh water makeup averages 30 to 50 gpm, with maximum fresh water
demand (up to 550 gpm) occurring in late summer. The rod mill discharges into the cyclone feed
sump, where cyanide is added at an average rate of 0.28 (maximum rate is 0.50) pounds per ton of
ore. The cyanide solution is made up by adding 50 pounds of caustic to each 3,000 pounds of
sodium cyanide. Caustic is added to maintain the pH of the working solution above 10. At 2,000
gallons per batch, a 3-day capacity of cyanide solution is maintained onsite (approximately 6,000 +.
2,000 gallons). The cyanide solution is transferred from a mixing tank, through the plant, to the
cyclone feed sump in schedule 80 steel pipe (see Appendix 5-B).
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Site Visit Report: Newmont Gold Company Rain Facility
Table 5-1. Analysis of Reclaim Water Returned to the Mill from the Tailings Impoundment
Sample:
Reclaim Water
Parameter
PH
IDS
WAD Cyanide
Antimony
Arsenic
Barium
Cadmium
Calcium
Chloride
Chromium
Copper
Fluoride
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nitrate
Selenium
Silver
Sodium
Sulfate
Thallium
Zinc
Sample Date
(values in ppm)
12-6-90
9.9
830
40.0
<0.05
0.19
0.47
0.009
140
69
< 0.005
5.5 .
5.2
0.35
< 0.005
0.95
< 0.005
0.32
< 0.082
17.0
0.27
< 0.005
140
310
< 0.005
0.99
3-4-91
10.0
660
14.0
<0.05
0.26
7.4
0.020
120
96
0.009
4.3
5.2
2.40
< 0.005
2.8
0.026
0.30
0.066
14.0
0.08
< 0.005
99
250
< 0.005
1.20
4-30-91
9.5
830
5.8
<0.05
0.23
0.080
< 0.005
140
110
< 0.005
3.7
5.3
0.28
< 0.005
3.4
< 0.005
0.33
0.065
14.0
0.05
< 0.005
130
310
<0.1
0.27
7-29-91
8.8
1600
9.6
<0.05
0.14
0.008
0.005
260
260
0.011
6.3
5.7
0.20
< 0.005
2.6
0.012
0.29
0.12
24.0
0.12
< 0.005
250
700
<0.1
0.21
Source: Data aggregated from quarterly reports submitted by Newmont to NDEQ as required by permit
5-16
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Sire Visit Report: Newmont Gold Company Rain Facility
Table 5-2. Analysis of Mill Water
Sample:
Mill Water Supply
Parameter
pH (s.u.)
TDS
WAD Cyanide
Arsenic
Barium
Bicarbonate
Cadmium
Calcium
Chloride
Chromium
Copper
Fluoride
Lead
Magnesium
Mercury
Nitrate + Nitrite
Selenium
Silver
Sodium
Sulfate
Zinc
Sample Date
(values in ppm)
12-30-90
8.1
210
< 0.005
< 0.005
0.17
170
< 0.005
33.0
12.0
< 0.005
< 0.005
<0.5
< 0.005
<0.01
<0.0001
0.14
< 0.005
< 0.005
24.0
16
< 0.005
Source: Data aggregated from information on file with NDEQ.
5-17
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Sire Visit Report: Newmont Gold Company Rain Facility
A pump transfers the slurry from the sump to four cyclone classifiers. Cyclone underflow is
transferred to secondary grinding to further reduce the particle size. An Allis-Chalmers 800-
horsepower ball mill is used to reduce coarse particles and discharges to the cyclone feed sump pump
for transfer back to the classifiers. Cyclone overflow passes a trash screen to remove wood and other
coarse material. These screens generate approximately one ton of trash per week, and the material
collected is hauled to the leach pad. Ore output from the classifier is 70 percent less than 200 mesh
(0.003 inches, or 74 microns) and is transferred to a 50,000-gallon surge tank before entering a series
of six leach tanks.
Each of the leach tanks has a capacity of 190,000 gallons (see Figure 5-5). A low concrete retaining
wall surrounds the surge and leach tanks; Newmont staff indicate that it would contain at least
190,000 gallons (the volume of one of the leach tanks). Cyanide may be added in the leach tanks as
needed, but this is not typically required at Ram. Ore slurry from the surge tank is transferred by
pump to the first leach tank. An agitator is used in each leach tank to keep the ore in suspension.
Air is injected to supply oxygen necessary for the cyanide to dissolve the gold. The slurry flows
continuously by gravity through tanks 1 to 6 (residence time in the leach tanks was not determined).
Both the path and flow rate are controlled by gate valves at the top of the tanks. As the slurry moves
through tanks 1 to 6, the barren cyanide solution leaches gold, silver, and some mercury from the
ore, forming a pregnant solution in the presence of the spent or leached ore. The total residence time
in the six leach tanks is approximately 36 hours.
From the leach tanks, the slurry is transferred to a series of six Carbon-In-Pulp (CIP) tanks (see
Figure 5-5). Each tank has a 50,000-gallon capacity; an agitator is used to keep the slurry in
suspension, and air is injected to promote adsorption of the metal-cyanide complex onto activated
carbon. The pregnant solution and spent ore enter tank number 1 and move by gravity toward tank
number 6. Activated carbon (6 by 12 mesh; 1.4 to 3.6 millimeters) is added to tank number 6 at a
rate of 2.2 tons per day and moves sequentially through tanks 5 to 1 every 24 hours. The carbon
slurry flows by gravity across a screen that traps the coarse grain carbon; from there, carbon is
advanced by pump to the next tank, counter-current to the slurry flow. With each succeeding tank
(from 6 to 1) the carbon adsorbs more of the gold. By contrast, less gold is in solution as the ore
slurry moves through succeeding tanks (from 1 to 6).
Loaded carbon exiting tank 1 contains approximately 250 ounces of gold per ton of carbon and lesser
quantities of silver and mercury. Carbon from the CIP circuit is washed over screens to remove fine
carbon particles. About 2.2 tons per day of coarser particles are pumped to a 10-ton holding tank
prior to shipment by truck to Newmont's Gold Quarry facility, where the gold is recovered from the
carbon and the carbon reactivated. After reactivation, the carbon is returned to the Rain facility.
Fine carbon particles that pass through the screen arc collected in drums until sufficient quantities
accumulate; about 2.6 tons of fine carbon product is generated each month. This is either shipped to
the Gold Quarry facility or to a third party to recover the metal values.
5-18
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Site Visit Report: Newmont Gold Company Rain Facility
Tailings composed of mill solution, spent ore, and small quantities of carbon that pass the screens in
the CIP tanks report to the tailings impoundment via a 12-inch diameter HDPE pipe 2,400 yards
long. Tailings exit the mill by gravity flow at approximately 800 gpm, containing 35 to 40 percent
solids. The solution has a pH of approximately 10, and weak acid dissociable cyanide of
approximately 30 parts per million (ppm) (Newmont Gold Company, Quarterly Monitoring Reports).
The facility is required to monitor tailings water quarterly from a spigot in the pipeline. Results of
four quarters between 1990 and 1991 are shown in Table 5-3.
On August 19, 1988, the tailings line became plugged, causing the mill tailings to leak out of the
vents in the line. According to Newmont, most of the leaking vents were within the limits of the
tailings impoundment. Newmont estimated that 12.46 pounds of cyanide were released in a 10.4 pH
solution. Both the Nevada Department of Emergency Management .(Incident No. 81908C) and the
National Response Center (Incident No. 11505) were notified. Cleanup consisted of scooping up the
material spilled outside the tailings impoundment and placing it within the limits of the impoundment.
To prevent the problem in the future, the tailings line was repositioned so that all vents would spill
into the limit of the tailings impoundment (Newmont Gold Company, 1988d).
In the event of a spill in the mill, floor drains in the concrete floor run to sumps in the grinding and
carbon handling areas. Fresh water may be used to flush material into the sumps for return to the
appropriate mill circuit. The surge, leach, and CIP tanks are located outside the mill building and are
surrounded by a low concrete retaining wall.
Blowers in the mill building exchange the air to avoid any buildup of cyanide gas. In addition,
workers must wear fully self-contained breathing apparatus for protection from fumes during the
mixing process. Alarms are located throughout the building and are activated if hydrogen cyanide
levels exceed five ppm. As reported during the site visit, this alarm has sounded one time, in
response to spilling one or two cyanide briquets on the floor while adding sodium cyanide to the
mixing tank.
5.2.3 Heap Leach
The Rain heap leach covers an area of approximately 71 acres in the valley above the tailings
impoundment (Newmont Gold Company, 1990d). Prior to constructing the pad, a French drain
system was installed to remove soil moisture seepage collected from the natural drainage system.
West and east drains were installed. These drains also collect any fugitive process fluids from the
pad. Fluid collected by the drains is transported to the tailings impoundment in a High Density
Polyethylene (HDPE) pipe (size unknown). According to Newmont, the west French drain discharges
an average of 0.88 gpm (maximum of 10.2 gpm), and the east French drain discharges an average of
0.29 gpm (maximum of 4.2 gpm) (Newmont Gold Company, 1991b). Discharge from these drains is
reported in Quarterly Monitoring Reports; data for the last three quarters is presented in Section
5.4.1.3.
5-19
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Site Visit Report: Newmont Gold Company Rain Facility
Table 5-3. Analysis of Tailings Water
Sample:
Tailings Water
Parameter .
pH (s.u.)
TDS
WAD Cyanide
Antimony
Arsenic
Barium
Cadmium
Calcium
Chloride
Chromium
Copper
Fluoride
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nitrate
Selenium
Silver
Sodium
Sulfate
Thallium
Zinc
Sample Date
(values in ppm)
12-6-90
9.9
590
35
<0.05
0.30
0.14
0.013
90
53
< 0.005
4.3
3.8
0.51
< 0.005
0.31
< 0.005
0.079
0.070
12.0
0.250
< 0.005
90
250
<0.005
0.74
3-4-91
10.6
440
25
<0.06
0.33
0.42
0.011
120
98
< 0.005
4.4
0.9
0.15
< 0.005
0.12
< 0.005
0.340
0.084
16.0
0.094
< 0.005
89
240
< 0.005
0.41
4-30-91
10.4
700
19
0.06
0.11
0.27
0.006
140
110
< 0.005
3.3
4.9
0.22
< 0.005
0.10
< 0.005
0.530
0.070
16.0
0.082
< 0.005
130
120
< 0.005
0.29
7-29-91
10.4
1500 I
20 |
0.17
38.00
2.50
0.150
730
280
2.300
10.0
1.6
1300
< 0.005 I
32.00
11.00
3.400
<0.05
26.0 I
0.140 |
0.005 |
260 1
120 1
3.2
0.48
Source: Data aggregated from quarterly reports submitted by Newmont to NDEQ as required by permit.
5-20
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Site Visit Report: Newmont Gold Company Rain Facility
The pad overlies the French drain system; it consists of 12 inches of compacted native soil covered by
an 80-mil HDPE synthetic liner; the synthetic liner is protected by an 18-inch layer of gravel. The
gravel is drained by a network of perforated collection pipes that collect the gold-laden leachate
(pregnant solution) and minimize the buildup of hydraulic head (NDEP, 1988a; Newmont Gold
Company, 1990d).
Ore is delivered to the pad in 100-ton haul trucks. The trucks deliver crushed ore from the leach ore
stockpile near the mill at an average rate of 3,150 (9,500 maximum) dry tons per day. Run-of-mine
ore is delivered directly from the pit at an average rate of 555 (6,000 maximum) dry tons per day.
As designed, the pad is divided into 30 cells, each covering approximately 100,000 square feet. The
pad is constructed in 20-foot lifts. Two lifts have been constructed. Ultimately, a total of 10 lifts
will bring the height of the heap to 200 feet. Leach ore is currently.placed on the pad at a rate of
about one million tons per year. Total capacity of the heap is 11 million tons.
Barren solution contains a working concentration of about 50 ppm cyanide. An average of 214
pounds of sodium cyanide is added to the barren solution per day to maintain a working
concentration, but peak demands may be as high as 400 pounds per day. Sodium hydroxide is added
to maintain a solution pH of about 10.0. The. average rate of addition is 437 pounds per day
(maximum of 1,000 pounds). Antiscalant is added to both the barren and pregnant solution at 14 cc
per minute to control scale build-up. Make-up water is added to the solution at a rate ranging from
less than one gpm in April and May to as high as 100 gpm during the hot, dry months of July and
August. A chemical analysis of the barren solution following makeup is presented in Table 5-4. The
solution is pumped to the heap at an average of 551 gpm, and applied at a rate of 0.006 gpm per
square foot (Newmont Gold Company, 1991b). This rate is sufficient to leach approximately one cell
at a time.
In warm months, the barren solution is applied using rotary sprinklers. During the site visit, some
ponding was observed on a portion of the heap surface, and spray was felt on another portion of the
heap, a short distance away from the cell being leached (according to the representative of the Nevada
Department of Wildlife who participated in the site visit, such ponding has not resulted in any wildlife
mortality at Rain). In winter, a drip system is used to prevent accumulation of ice on the surface «>t
the heap. Lime is added directly to the top of the heap as needed to maintain the solution pH at or
near 10. According to the environmental assessment (Newmont Services, 1987b), 10 percent of the
solution applied to the heap was expected to be lost to evaporation and a smaller portion absorbed h>
the ore material.
Once applied to the heap, the barren cyanide solution dissolves the gold values. The solution, *ith
increasing amounts of gold, percolates through the pile to the perforated pipe located above the liner
The pipes convey the pregnant solution to lined collection ditches that extend around three sides i v
pad and connect to the pregnant solution pond. The pregnant pond is located at the base of the >u-jr
5-21
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Site Visit Report: Newmont Gold Company Rain Facility
Table 5-4. Analysis of Barren Solution
Sample:
Barren Solution
Parameter
pH(s.u.)
TDS
WAD Cyanide
Antimony
Arsenic
Barium
Cadmium
Calcium
Chloride
Chromium
Copper
Fluoride
Iron
Lead .
Magnesium
Manganese
Mercury
Molybdenum
Nitrate
Selenium
Silver
Sodium
Sulfate
Thallium
Zinc
Sample Date
(values in ppm)
12-6-90
9.4
930
34.0
< 0.050
0.21
0.09
0.018
190
120
0.056
6.2
1.2
0.55
< 0.005
1.70
0.038
4.6
0.100
56
0.120
< 0.005
120.0
260.0
<0.01
0.35
3-4-91
10.3
660
24.0
< 0.005
0.67
0!07
0.019
150
130
0.100
6.4
1.9
0.05
< 0.005
0.33
< 0.005
3.6
0.320
37
0.090
< 0.005
71.0
170.0
< 0.005
0.13
4-30-91
10.1
930
34.0
< 0.050
0.52
0.07
0.016
150
110
0.054
6.2
1.5
0.11
< 0.005
1.20
< 0.005
1.7
0.170
38
0.061
< 0.005
130.0
250.0
<0.01
0.23
7-29-91
10.1
1900
66.0
< 0.050
0.59
<0.05
0.014
160
170
0.019
9.1
1.4
0.47
< 0.005
1.80
0.027
6.1
0.082
43
0.080
< 0.005
430.0
860.0
<0.10
0.28
Source: Data aggregated from quarterly reports submitted by Newmont to NDEQ as required by permit.
5-22
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Site Visit Report: Newmont Gold Company Rain Facility
in the valley bottom above the tailings impoundment. The pond is designed to hold five million
gallons of solution. It is double lined with a leachate detection and recovery system between the
liners. The lower liner, of unspecified-grade HDPE, overlies 12 inches of compacted native clay. A
geotextile material was installed above the lower liner to allow detection and, as necessary, collection
of any fugitive pregnant solution escaping the 80-mil HDPE primary liner. In the event that solution
is observed, a sump is used to pump liquid to the tailings impoundment. According to Newmont, the
leak detection system recovers an average of 0.38 gallons per day (gpd) and a maximum of 15 gpd.
If the pregnant pond overflows, solution enters a ditch lined with an 80-mil HDPE liner, which drains
by gravity to the tailings impoundment. Solution concentrations and Newmont's management strategy
are discussed in Rain's "Fluid Management Plan, Best Management Plan" (NDEP, 1988a; and .-
Newmont Gold Company, 1991b).
x *
As a requirement of their Water Pollution Control Permit, Newmont analyzes pregnant solution
chemistry quarterly. In the past 4 quarters, pH values have ranged from 9.8 to 10.3; WAD cyanide
from 19 to 53 ppm; sulfate from 180 to 880 ppm; and mercury from 3.9 to 6.9 ppm. Chemical
analysis of the pregnant solution for this period is presented in Table 5-5. A pump transfers the
pregnant solution to the Carbon-In-Column (CIC) circuit in the mill building at a rate of
approximately 550 gpm. The Rain CIC circuit consists of five columns, each with a capacity of
approximately 2,000 gallons. Pregnant solution enters column number 1 (see Figure 5-5). Fresh,
activated carbon (6-by-12 mesh; 1.4 to 3.6 mm) enters column number 5 at an average of 0.4 tons
per day (maximum 1.0) and is pumped sequentially through tanks 5 to 1. In the tanks, the solution
flows by gravity across a carbon screen. The carbon collected on the screen is advanced by pump on
an hourly basis to the next tank, counter-current to the solution flow. With each succeeding tank
(from 5 to 1) the carbon adsorbs more of the gold. By contrast, less gold is in solution as the
pregnant solution moves through succeeding tanks (from 1 to 5). Fully loaded carbon exits tank
number 1 and is pumped to the 10-ton holding tank for transfer to the Gold Quarry facility. Barren
solution exits tank number 5 and is returned to the barren solution make-up tank in the mill building,
where cyanide, sodium hydroxide (to buffer the pH), and water are added prior to recycling it back to
the heap.
The Rain operation does not use a barren solution pond in its fluid management system. All the
solution resides in the process circuit, the heap, and the pregnant pond.
5.2.4 Facility Control Room
As pan of the facility walkthrough, site visit participants viewed the mill control room as well as the
equipment and vehicle maintenance building. The control room monitors and controls mill tonnage.
slurry flow rates, solution chemistry, and various liquid levels in tanks throughout the mill building
An operator is on duty at all times to note changes and record conditions at scheduled intervals.
Cyanide levels in the leach and mill circuits are determined by the operator every two hours by
titration with silver nitrate; these values are averaged every 24 hours.
5-23
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Site Visit Report: Newmont Gold Company Rain Facility
Table 5-5. Analysis of Pregnant Solution
Sample:
Pregnant
Solution
Parameter
PH (s.u.)
TDS
WAD Cyanide
Antimony
Arsenic
Barium
Cadmium
Calcium
Chloride
Chromium
Copper
Fluoride
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nitrate
Selenium
Silver
Sodium
Sulfate
Thallium
Zinc
Sample Date
(values in ppm)
12-6-90
9.8
910
53.0
<0.05
0.22
0.09
0.017
160
110
0.06
6.2
1.4
0.56
< 0.005
1.7
0.041
6.9
0.1
50
0.14
0.006
95
220
<0.01
0.36
3-4-91
10.3
750
28.0
<0.05
0.65
<0.06
0.019
150
130
0.1
6.5
1.9
0.04
< 0.005
0.54
< 0.005
4.6
0.32
38
0.092
< 0.005
92
180
< 0.005
0.13
4-30-91
9.8
900
19.0
<0.05
0.52
0.08
0.016
150
80
0.056
6.6
1.6
0.08
< 0.005
1.2
< 0.005
3.9
0.17
37
0.084
< 0.005
110
240
<0.01
0.23
7-29-91
10.0
1800
28.0
<0.05
0.56
<0.05
0.017
160
160
0.019
9.2
1.4
0.45
< 0.005
1.9
0.027
4.3
0.079
19
0.085
O.OCW
400
880
<0.1
0.2*
Source: Data aggregated from quarterly reports submitted by Newmont to NDEQ as required by pc
5-24
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Site Visit Report: Newmont Gold Company Rain Facility
5.3 MATERIALS AND WASTE MANAGEMENT
For purposes of this discussion, materials management practices at the Rain facility are divided into
process and waste management units. Process units are those that contain materials that are not
considered wastes until after facility closure. Examples of process units (and process materials) are
heap leach pads (and spent ore) and the open pit (and mine water that may reside in the pit). Waste
units are those that contain materials that will undergo no further beneficiation. Examples of these
include waste rock piles and the tailings impoundment.
Waste rock removed from the pit during mining is disposed in the waste rock dump. Mill tailings are
disposed in the tailings impoundment. Tailings water is recycled to the mill or heap continuously
until facility closure. Smaller volumes of other wastes generated onsite include sanitary sewage,
waste oil, grease, used tires, and refuse.
5.3.1 Mine Pit and Heap Leach
According to Newmont, closure is tentatively scheduled for 1995. Mill activity will cease about one
year before leaching ends. However, experience at the Newmont Gold Quarry facility indicates
active leaching may continue for two to three years following the last addition of ore (Newmont Gold
Company, 1990d).
The final depth of the Rain Pit may reach 6,240 feet asl. According to Newmont, it is not expected
to extend below the water table, though perched aquifers may be encountered. Inflow to the pit by
direct precipitation and ground water is not expected to cause ponding in the pit. In addition,
Newmont will construct diversion ditches on the slope above the pit to limit surface water inflow
(Newmont Gold Company, 1990d).
The mill leach circuit will stop operation when all mill grade ore is removed from the pit. The
remaining mill solution will be combined with the leach circuit. The CIC circuit will continue to
recover gold values until heap leaching stops as noted above. Newmont has not indicated what will
be done with the mill facility in their Tentative Closure Plan (Newmont Gold Company, 1990d).
Section 5.2.3 above describes the construction of the heap leach and the quantities of spent ore (i.e.,
up to 11 million tons) that will remain on the pad at closure. At closure, the spent ore will be rinsed
to meet State of Nevada regulations, which require that effluent rinse water have weak acid
dissociable (WAD) cyanide levels below 0.2 mg/liter and a pH between 6 and 9. As currently
planned, fresh water will be used to rinse the heap The addition of calcium hypochlorite, ferric
sulfide, hydrogen peroxide, or other chemicals may be required to detoxify the residual cyanide in the
heap. A second rinse with the possible addition of acid may be required to lower the pH. Following
the rinse cycle, the leaching solution will require disposal Newmont is conducting test work on the
best method to rinse the spent ore. According to the environmental assessment (Newmont Services.
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Site Visit Report: Newmont Gold Company Rain Facility
1987b), the heaps will be covered with topsoil and revegetated. Newmont also is considering
reclamation as a means to mitigate the concern for mobilization of contaminants by meteoric water.
The premise is that infiltration will be eliminated by a soil and vegetation cover (Newmont Gold
Company, 1990d). As described in Section 5.4.1.2, Newmont is in the process of preparing a
reclamation plan for submission to the State (Newmont Services, 1987b).
5.3.2 Waste Rock Dump
Currently, the waste rock dump covers 211 acres and is located north and east of the pit. Waste rock
production from the pit averages 29,500 tons per day. Of this, 7,500 tons are sulfidic and 22,000
tons oxide. Newmont estimates that by mine closure in 1995, there will be 62.5 million tons of waste
rock; of this, 77.8 percent is expected to be mostly oxidized mixed sedimentary material of the Webb
Formation (some of which will contain sulfide mineralization), 15.4"percent will be carbonaceous and
potentially sulfidic, 4.3 percent will be limestone of the Devil's Gate Formation, and 2.5 percent will
be alluvium from surface deposits. Based on mining records prior to August 1990 and the expected
future mining schedule, waste rock tonnage by type of rock is presented in Table 5-6. The
distribution of carbonaceous versus total waste in the waste rock dump as of June 1990 is presented in
Figure 5-6 (SRK, 1990; Newmont Gold Company, 1990d).
Table 5-6. Projected Waste Rock Generation (Waste Tonnages X 1000)
Year
to 8/90
8/90 to 12/90
1991
1992
1993
1994
1995
TOTAL
Total
34,768
6,630
7,169
6,352
5,154
2,180
267
62,520
Carbonaceous
5,187
815
2,050
969
544
38
9,603
Limestone
222
645
824
823
205
2,719
Other
29,049
5,389
4,508
4,521
3,786
1,319
62
48,634
Alluvium
310
426
611
217
,
1,564
Source: SRK, 1990
Prior to the spring of 1990, sulfide, oxide, and calcareous waste rock were disposed together. On
May 8, 1990, acid drainage was observed flowing from the base of the waste rock dump and into the
unnamed drainage above Emigrant Spring, toward Dixie Creek. Inspection of the drainage
downstream of the dump revealed that approximately two miles of the channel contained a red-brown
precipitate. Discharge to the drainage was estimated by Newmont to be 3 gpm. Surface-water
samples were taken along 5 points in the drainage above and below Emigrant Springs in May, June.
5-26
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I BECKER DHIUHOIE
LOCATION
76t?l£- CARBONACEOUS
4.2S«.Mt TO1AL WASTE
PERCENTAGE OF
CARBONACEOUS
SCALE:
f- 400
f
I
I
Figure 5-6. Percent of Carbonaceous and Other Waste Rock in Waste Rock Dump
(Source: SRK 1990)
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Site Visit Report: Newmont Gold Company Rain Facility
and July of 1990. They showed pH values ranging from 2.37 to 3.21 near the base of the waste rock
at the discharge point, and from 6.5 to 8.64 about 4,000 feet downstream. Arsenic near the effluent
point was 46 ppm in May and 1.5 ppm in July; at the distant sampling point, arsenic was 0.023 ppm
in May and 0.005 ppm in July. Mercury near the discharge point was 0.19 ppm in May and 0.0019
ppm in July; at the distant sampling point, mercury was < 0.0001 ppm in May and 0.0003 ppm in
July (SRK, 1990). Results of the chemical analyses are presented in Appendix 5-B, Tables 5-14
through 5-19.
In response to the drainage, Newmont took the following actions. By May 9 (one day after the
drainage was noted), a small pond was constructed to collect the flow from the dump. On May 11,
an HDPE liner was installed in the pond. On May 18, Newmont constructed a cutoff trench across
the channel downstream of the collection pond to collect subsurface solution. The trench was twenty
feet deep and forty feet across and included a HDPE liner. Inflow to this trench was pumped to the
collection pond and then trucked to the tailings impoundment for disposal (Newmont Gold Company,
1990b).
Newmont notified the Nevada Division of Environmental Protection (NDEP) of the situation on May
10, 1990.
Newmont's assessment of the acid drainage problem noted that it occurred during the snowmelt
period of 1990 and cites two contributing factors for the occurrence of discharge. First, snow
accumulation removed from other areas of the facility was disposed of on a localized area of the
dump. The volume in the pile may have represented as much as 5 to 15 times the average snow
pack. Second, the premining topography of the dump area collects and concentrates surface drainage
from a watershed of about 35 acres. As the snow melted, it infiltrated the waste rock pile, oxidizing
sulfur-bearing minerals and generating acid. The solution migrated along premining topography and
discharged at the toe of the dump.
Long-term mitigation of the acid drainage problem was proposed by Newmont in the "Rain Project
Solution Collection and Return System Design Report" (SRK, 1990). The State and BLM approved
the plan and construction began in November of 1990 and was completed in March of 1991. The
solution collection and return system consists of surface and subsurface water collection and recovery.
Surface water is collected by a ditch and drains to a sump located at the toe of the waste rock pile.
Drainage collected by the sump drains by gravity to a 200,000-gallon capacity, double-lined pond.
Subsurface flow is recovered in an HDPE-lined trench and also drains to the double-lined pond. At
the time of the site visit, discharge from the waste rock dump was estimated to be less than one gpm.
Following the site visit, Newmont supplied data indicating that flows average 23.8 gpm with a
maximum of 183 gpm (Newmont Gold Company. I991b). In the event of a power failure, the pond
has a capacity to retain in excess of 65 hours of inflow at the maximum projected flow. In addition.
storm water from the surface of the waste rock dump and surrounding area is collected in a single-
5-28
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Sire Visit Report: Newmont Gold Company Rain Facility
lined, 600,000-gallon pond located just below the double-lined pond. Solution from both ponds is
pumped to the mill area and added to the tailings pipeline (SRK, 1990).
In addition to these engineering designs for acid drainage recovery, Newmont has changed its waste
rock disposal practices for material with the potential to generate acid drainage. Of the final
estimated volume of waste rock, approximately 15 percent (9.6 million tons) is expected to be
carbonaceous and potentially sulfidic. More than one half of this was generated before the acid
drainage problem developed in May of 1990. Prior to this, sulfide material was mixed with oxidized
material or the limited quantity of calcarious material available to buffer any acidic solution
generated. The sulfidic materials are fine to coarse grain sedimentary rocks extracted primarily from
the Webb Formation.
Sulfidic waste rock is now being encapsulated within oxidized and/or calcareous waste rock that has
either no net acid generating potential or some acid neutralizing potential. This is accomplished by
placing a pervious layer of coarse oxidized waste rock on the native soil. On this, five feet of
compacted oxidized ore is placed. Additional oxide ore is placed against the natural hillslope to act as
a barrier. These layers act as barriers to water movement into and out of the sulfide waste rock.
Following these steps, sulfidic waste rock is placed on, and in front of, the oxide ore. Several lifts
are expected to be added to the sulfide waste pile. Haul trucks follow random routes during
construction to compact the material, thereby reducing its permeability. Eventually, the front edge
and top will be covered with IS feet of oxidized material to complete the encapsulation.
As part of the revised Water Pollution Control Permit (see Section 5.4), Newmont reports quarterly
on results of Meteoric Water Mobility testing and Waste Rock Analysis (see Appendix 5-E for NDEP
guidance on this procedure). The meteoric mobility test is an extraction procedure. The extracted
solution is analyzed for nitrate, phosphorous, chloride, fluoride, total dissolved solids, alkalinity,
sulfate, and metals. Waste rock analysis is intended to determine the net acid generation potential of
the material placed in the waste rock dump during the quarter. Samples are collected daily during the
quarter and classified based on their net carbonate value as sulfate, highly basic, basic, slightly basic,
neutral, slightly acidic, acidic, or highly acidic. The quarterly composite sample to be analyzed is
prepared on a tonnage weighted average for each classification and aggregated prior to analysis.
Data were available for the third and fourth quarters of 1990 and the first quarter of 1991. Results of
the meteoric water mobility test for this period are presented in Appendix 5-C, Tables C-1, C-2, and
C-3. Third quarter results for the waste rock analysis indicate a net acid generation potential of -10.6
tons of CaCO3 for each 1,000 tons of waste. This suggests that the wastes generated during this
quarter have sufficient buffering capacity to neutralize any acid solution generated by sulfidic
material. Fourth quarter results show a large shift, with an acid generating potential of 5.35 tons of
CaCOj for each 1,000 tons of waste. The total acid generating potential of waste rock disposed
during this quarter is equivalent to.the amount of acid neutralized by 5.35 tons of CaCO3 for each
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Site Visit Report: Newmont Gold Company Rain Facility
1,000 tons of waste rock. For the first quarter of 1991, waste rock analysis data show a net acid
generating potential of 8.57 tons. In these circumstances, Newmont is required to perform kinetic
testing according to State of Nevada protocol. Results of this analysis were not available; however,
in the third Quarterly Monitoring Report for 1991, Newmont indicated that column studies are
underway to fulfill this requirement.
The waste rock dump is not expected to require more space than the 211 acres it currently covers;
however, waste rock will continue to be added, with a projected total of 62.5 million tons by 1995.
At closure, the surface will be graded. Topsoil stockpiled during start-up (and which is presently
stockpiled near the dump and was observed during the site visit to have a vegetative cover of grasses)
will be distributed over disturbed areas and re vegetated.
5.3.3 Tailings Impoundment
The Rain tailings impoundment is located downgradient from the heap leach facility and pregnant
pond. According to the environmental assessment (Newmont Services, 1987b), the impoundment was
originally planned to cover 109 acres. The ultimate surface area of the impoundment is now
anticipated to be approximately 189 acres, with a total capacity of about 6.7 million dry tons of
tailings (Newmont Gold company, 1990d). The impoundment is designed to contain the flow in the
watershed from the 100-year, 24-hour storm event (the original Water Pollution Control Permit
required containment for the 100 year, 72-hour storm event, with an additional two feet of free board;
this was modified to the present capacity in a 1990 amendment [the permit is discussed in section
5.4.1.3]). The structure is designed to withstand the maximum credible earthquake expected in the
area (Newmont Services, 1987b). Originally, the impoundment was to be a "bathtub" design,
containing all fluids with no discharge beyond the tailings impoundment dam (NDEP, 1989); this has
since changed, as described below. Monitoring wells were installed downgradient of the dam to
verify the facility's compliance with its design standard of zero discharge.
Construction of the tailings dam began in October 1987 and was completed by the summer of 1988.
Since initial construction, two additional lifts have been added to the dam to expand the storage
capacity of the impoundment, and additional lifts are planned. The first lift was added in 1989, the
second in 1990. Figure 5-7 is a cross-section of the dam showing the three phases of construction.
Tailings from the mill are added to the inside face of the embankment so slimes can accumulate and
form a barrier; tailings form an upstream slope away from the dam. Water ponds at the base of this
slope, in the upper portion of the impoundment away from the dam. Supernatant is reclaimed and
returned to the mill as process water. Keeping the supernatant pond in the upper reaches of the
impoundment reduces the gradient of the phreatic line and thus the potential for seepage through the
lower impoundment and the dam.
According to the environmental assessment, most of the tailings impoundment was underlain by
naturally occurring highly impermeable clay. The maximum permeability was 10'7 cm/sec., with
5-30
-------
-I I -* «tkt*t (* ' it
al t **^" I t.n->i "-f* *«»
I/I
U)
I
a
Figure 5-7. 1990 Tailings Facility Expansion
Kni^hl I'icsold
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Site Visit Report: Newmont Gold Company Rain Facility
some areas having permeabilities of 10'8 or 10'9 cm/sec. An area on the nprthwest side of the future .
dam location consisted of alluvial material having a potentially high seepage rate. This area was to be
covered with a clay liner similar to the natural clay material. The core of the dam was also to be
constructed of the same material (Newmont Services, 1987b).
The initial dam structure was designed (by Call and Nicholas Inc.) as an earth fill embankment
consisting of a compacted clay core with random fill shells of mine waste rock. A cutoff trench was
excavated and backfilled with clayey soil to a depth of seven feet below the original ground surface
prior to constructing the embankment. A near-vertical granular chimney drain was built along the
length of the dam, about halfway up the downstream side of the structure (see Figure 5-7). The
chimney drain is hydraulically connected to a blanket drain located at the base of the embankment on
the downgradient side. The final elevation of the initial structure was 6409 feet asl (Knight Piesold,
1990).
In April 1988, during construction of the Rain facility, seepage (about 7.5 gallons per minute) was
noted in the natural drainage channel about 300 feet downgradient of the tailings impoundment dam.
Newmont retained Sergent, Hauskins & Beckwith to develop a mitigation plan to control seepage.
Following a tracer study supervised by Geraghty & Miller, Inc., it was determined that the seepage
was coming from the dam interiorliquids in the impoundment were migrating through the upstream
face of the dam to the chimney drain and exiting the blanket drain on the downstream side. In June,
Newmont took action to prevent continued seepage into and through the dam. To control seepage
into the structure, a second keyway was excavated along the toe area on the inside face and backfilled
with clayey soil (taken from a borrow pit in the upper reaches of the impoundment area-this pit then
was used as temporary storage area for tailings while the impoundment remediation was underway).
Newmont also placed a four-foot thick clay liner extending from the top of this keyway to the
upstream toe of the dam. Soil liners (material unknown) were installed on the bedrock face forming
the east abutment with the dam. Downgradient of the dam, a seepage collection pond was excavated
to bedrock. Initially, this pond was pumped periodically, and later a permanent pump was installed to
return seepage to the tailings impoundment. Just below the collection pond, a 60-mil HOPE barrier
wall, backfilled with clay materials and capped with clay and random fill, was installed to prevent
further migration of the seepage (see Figure 5-8). In addition, a 15- to 20-foot deep trench drain was
excavated to bedrock, below the ultimate extent of the dam, parallel to the northwestern face of the
impoundment and extending to the seepage collection pond (this drain is intended to direct any
seepage from this end of the dam to the collection pond).
Additional monitoring wells were also constructed downgradient of the impoundment and the seepage
collection pond (Newmont Gold Company, 1988e).
The tailings impoundment began operation in July 1988. Cyanide was first detected in the seepage
collection pond and, to a lesser degree, in the monitoring wells located downstream of the collection
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Site Visit Report: Newmont Gold Company Rain Facility
pond, in October of 1988. The location of the monitoring wells in relation to the seepage pond is
shown on Figure 5-8. Seepage rates increased in November 1988, causing the solution in the
collection pond to overflow the HDPE barrier and enter the natural drainage (the exact distance the
fluids traveled was not determined). WAD cyanide concentrations in the seepage pond ranged from a
high of 11.6 mg/1 in October to 63 mg/1 in December of 1988; monitoring well 3 ranged from 0.17
mg/1 in October to 8.8 mg/1 in December. Information on cyanide concentrations for the seepage
pond and monitoring wells between July 1988 and July 1989 is presented in Appendix 5-D, Tables
5-20 and 5-21. Solution chemistry of the seepage collection pond water is presented in Table 5-7.
Following this release, a permanent pump was installed. (As reported by Newmont on April 14,
1989, the seepage collection pond was being continuously pumped at a rate of 288,000 gallons per
day, or 200 gpm.) (Newmont Gold Company, 1989e).
Newmont responded to the situation with a description of efforts to control seepage of process fluids.
Sergent, Hauskins & Beckwith developed a plan to determine the source and control the seepage. In
the short term, work focused on a field program of exploratory drilling and hydrologic testing to
identify the seepage pathways downstream of the collection pond and develop remedial alternatives
(Newmont Gold Company, 1989c). Based on these investigations, it was determined that seepage
from the impoundment was confined to the alluvial material and weathered bedrock of the Webb
Formation (Newmont Gold Company, 1989f).
The recovery system selected by Newmont and approved by NDEP on March 15, 1989, consisted of
an upstream trench drain and a downstream trench drain. The upper trench drain is located just
below the seepage collection pond and HDPE barrier and is designed to intercept fluids that escape or
bypass the seepage collection pond and barrier wall. It extends 160 feet across the drainage and is
approximately 30 feet deep. The bottom of the trench is keyed into bedrock and slopes to a sump.
An HDPE liner was installed on the downstream face and the trench was backfilled with coarse
material. A pump was installed to return solution to the seepage collection pond (from which liquids
were initially pumped directly to the tailings impoundment and now are pumped to the underdrainage
collection pond described below).
The lower trench drain is located about 1,000 feet downstream of the upper trench drain and is
intended to intercept the plume that escaped when the seepage pond overflowed in November 1988
Construction of the lower trench drain, also keyed into bedrock, was similar to that of the upper
trench drain; however, it is shallower, based on field evidence that the plume is moving near to the
surface. As with the upstream trench drain, a pump returns any liquids to the seepage collection
pond. (Newmont Gold Company, 1989d).
A downstream lift and additional fluid management components, designed by Knight Piesold and (
were added to the tailings impoundment dam in late 1989 (see Figure 5-7). These improvement-.
were added both to expand the capacity of the impoundment and to improve the impoundment'-
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Site Visit Report: Newmont Gold Company Rain Facility
Table 5-7. Analysis of Seepage Pond Water (CP)
Sample:
Seepage Pond
Water (CP)
Parameter
pH (s.u.)
TDS
WAD Cyanide
Antimony
Arsenic
Barium
Bicarbonate
Cadmium
Calcium
Chloride
Chromium
Copper
Fluoride .
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nitrate
Selenium
Silver
Sodium
Sulfate
Thallium
Zinc
Sample Date
(values in ppm)
12-6-90
7.7
820
0.590
< 0.005
0.14
210
< 0.005
120
67
< 0.005
0.049
0.6
0.01
< 0.005
29
2.9
0.010
~
8.0
0.010
< 0.005
100
380
0.014
3-5-91
7.1
890
0.200
< 0.005
0.12
180
< 0.005
130
61
< 0.005
0.042
<0.5
<0.01
< 0.005
33
2.7
0.002
4.7
<0.01
< 0.005
. HO
360
--
< 0.005
5-1-91
7.3
900
0.057
< 0.005
0.11 -
160
< 0.005
150 -
84
< 0.005
0.120
<0.5
<0.01
< 0.005
34
1.8
0.010
7.4
0.016
< 0,005
82
320
< 0.005
7-31-91
7.8
868
0.088
< 0.005
0.13
210
< 0.005
130
77
0.006
0.082
0.5
0.12
0.120
28
2.5
0.010
"
3.1
0.014
< 0.005
110
400
0.008
Source: Data aggregated from quarterly reports submitted by Newmont to NDEQ as required by permit.
5-35
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Site Visit Report: Newmont Gold Company Rain Facility
environmental performance by "making a gradual transition from an essentially undrained facility to a
functionally drained facility" (Knight Piesold, 1990). The clay core and blanket drain of the original
dam were extended vertically and the crest of the dam was increased by 16 feet to an elevation of
6425 feet asl. In addition, an underdrainage collection system was added to control seepage as the
basin fills and the pond migrates upstream. The underdrain system is also intended to aid in the
consolidation of the tailings by accelerating the dewatering process (Knight Piesold, 1990).
The underdrain collection system was constructed in the upper valley areas where tailings would reach
as the impoundment filled (and is to be extended as the impoundment is expanded in the future). It
consists of a one-foot layer of compacted native soil (1 x 10"6 to 1 x 10~7 cm/sec) overlain with a
drainage blanket/hydraulic break of 12 inches of select waste rock. Drainage lines of four-inch
diameter perforated pipe are installed at intervals in the waste rock layer. Drainage from the pipes
discharge to an 8-inch HDPE pipe around the area, which passes in turn through the tailings dam in a
concrete encasement to an underdrainage collection pond. In addition, a transition area between the
pond level at the time (late 1989) and the functional elevation of the underdrainage collection system
was double-lined, with a 30-mil PVC liner over a natural soil liner (Knight Piesold, 1990).
The underdrainage collection system, as noted above, drains by gravity to an underdrainage collection
pond just below the downstream face of the impoundment dam. This pond also receives pumpback
from the seepage collection pond. The underdrainage collection pond is HDPE-lined with a capacity
of 500,000 gallons. Solution collected in the pond is pumped back to the supernatant pond by means
of a submersible pump. Figure 5-9 shows the location of the underdrain system and the collection
pond (Knight Piesold, 1990). As part of the quarterly monitoring required by their Water Pollution
Control Permit, Newmont analyzes the underdrainage water. A chemical analysis of the
underdrainage solution is presented in Table 5-8.
A second lift, this time an upstream lift with downstream construction, and an expanded
underdrainage system, was designed by Knight Piesold and Co. and built in 1990. This construction
raised the dam elevation to 6,432 feet asl. Upstream fill construction consisted of earth and waste
rock surrounding an extension of the dam's clay core.
A one- to two-foot layer of waste rock was placed on the upstream face; fluid that collects in this
system will be drained through collector pipes to the underdrainage collection pond. Future lifts of
similar upstream construction are planned, which will raise the final elevation of the dam to 6,475
feet asl. The impoundment's ultimate design capacity is for 6.7 million dry tons of tailings.
Designed fluid capacity for the operational pond is for up to 150 acre-feet of water, plus flow from
the 100-year, 24-hour storm event, with at least three feet of freeboard. (Knight Piesold, 1990)
5-36
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UJ
g
r
a
£>
s
Figure 5-9. 1990 Tailings Facility Expansion, Main Embankment Plan
(Source: Knight Piesold 1990)
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Site Visit Report: Newmont Gold Company Rain Facility
Table 5-8. Analysis of Underdrainage Water
Sample:
Underdrainage
Water
Parameter
PH
TDS
WAD Cyanide
Antimony
Arsenic
Barium
Cadmium
Calcium
Chloride
Chromium
Copper
Fluoride
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nitrate
Selenium
Silver
Sodium
Sulfate
Thallium
Zinc
Sample Date
(values in ppm)
>
12-6-90
7.6
1100
2.7
<0.05
0.035
0.26
< 0.005
160
94
< 0.005
0.68
<0.05
0.61
0.032
31
2.4
0.0099
0.025
7.4
0.032
< 0.005
95
490
<0.05
0.053
3-5-91
8.0
1100
1.4
<0.05
0.068
0.15
< 0.005
160
130
< 0.005
1.00
0.5
0.50
< 0.005
28
1.8
0.0021
0.034
8.7
0.028
< 0.005
110
410
<0.05
0.065
5-1-91
8.0
1100
1.9
<0.05
0.100
0.17
< 0.005
170
180
< 0.005
1.60
2.1
0.20
< 0.005
23
1.3
0.0800
0.044
14.0
0.042
< 0.005
120
360
< 0.005
0.100
8-01-91
8.0
1200
0.029
0.059
0.1
< 0.005
180
150
0.012
0.35
0.9
0.29
< 0.005
27
2.1
0.0091
7.0
0.042
< 0.005
110
500
0.048
Source: Data aggregated from quarterly reports submitted by Newmont to NDEQ as required by permit.
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Site Visit Report: Newmont Gold Company Rain Facility
With the completion of the 1989 and 1990 expansions and construction, all fluids collected by the
seepage collection pond, upper and lower trench drains, "and the underdrainage collection system
drains by gravity or is pumped to the underdrain collection pond. From there, the solution is pumped
back to the tailings impoundment supernatant pond where it is available for recycle to the mill.
Newmont reported the chemistry of the tailings solids as part of the Quarterly Monitoring Report until
the third quarter of 1990. Table 5-9 is a summary of monitoring results.
Table 5-9. Chemical Analyses of Tailings Solids for First Three Quarters, 1990
Analyte -
Cadmium
Copper
Mercury
Lead
Zinc
Concentrations in rag/kg except as noted
January 15, 1990
0.0086
0.0250
0.0210
< 0.0150
0.048
April 4, 1990
0.0039
0.0065
0.023
< 0.00025
0.007
Third Quarter,
1990
0.0063
0.019
0.019
0.0091
Not reported
Newmont's "Tentative Permanent Closure Plan" (Newmont Gold Company, 1990d) indicates that
limiting runon onto the impoundment and removing existing fluids are primary goals of closure.
(According to Newmont, the "Tentative Permanent Closure Plan" is "tentative" hi the sense that it has
not yet been implemented and may be amended as events require, not because of any lack of
development.) Supernatant from the tailings impoundment will be pumped to the leach facility, as
will solution collected in the underdrainage collection pond and the seepage collection pond. By
controlling runon and disposing of supernatant, Newmont anticipates a "gradual draining of the
noncapillary fluid from the facility;" this in turn is anticipated to result in a cessation of seepage into
the underdrain system and the seepage collection pond. If drying of the tailings impoundment surface
presents a wind erosion problem, the surface may be covered with waste rock and/or native grass hay
and/or windbreaks may be used. In addition, solid tailings will be sampled on an annual basis. The
environmental assessment (Newmont Services, 1987b) indicated that the impoundment area would be
covered with waste rock and that tests would be undertaken to determine the feasibility of establishing
vegetation on that waste rock.
53.4 Water Management
Process water is carefully managed at the facility. According to Newmont, the Rain operation
consumes fresh water at a rate of approximately 100 gpm on an annual basis. During dry periods,
consumption may reach or exceed 600 gpm. The average usage represents less than 10 percent of the
water moving through the system at any given time and. assuming the water volume onsite remains
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Site Visit Report: Newmont Gold Company Rain Facility
constant, this amounts to 140,000 gpd. Most water loss is due to evaporation from the tailings
impoundment, heap leach, and road watering to control 'dust. Water from the tailings impoundment
and leach circuit are recycled to the mill for distribution. A small volume of additional water is
collected from local surface-water run-off control and from the waste rock dump in the form of acid
drainage and transferred to the tailings impoundment. Similarly, seepage from the tailings
impoundment and any leachate from the leach pads and solution ponds are returned to the tailings
impoundment. As described above, Newmont expects seepage from the tailings impoundment to be
reduced or to end following closure, and also anticipates that there will be little or no infiltration and
seepage from the waste rock dump following closure.
5.3.5 Other Materials and Wastes
Table 5-10 lists several of the materials and wastes handled by the Rain facility. The facility uses a
small landfill (Class III under Nevada regulations) to dispose of solid waste generated by the facility.
During the site visit, participants observed items such as paper, cardboard, and empty reagent drums
in the trench landfill. Hazardous wastes or petroleum liquids are not disposed of in the landfill. A
permit was issued for the landfill in October 1989 by the Nevada Waste Management Bureau. The
landfill is located on the south rim of the mine pit at an elevation of approximately 6750 feet. As the
trench is filled it is covered with soil material. The average amount of waste generated is 40 cubic
yards of uncompacted waste per week: 12 cubic yards from the mill and office sources and 28 from
the truck shop.
In an effort to minimize waste associated with facility maintenance such as metal cleaning, the Rain
operation is experimenting with a HOTSY (manufacturer's name) steam cleaner. In the past, Safety-
Kleen Corporation supplied an asphalt solvent containing trichlorethylene, which was returned to
Safety-Kleen for regeneration. The shipments were manifested in accordance with Nevada hazardous
waste regulations. The frequency and sizes of shipments were not determined (a shipment on June
12, 1991, involved 258 gallons). The new process uses citrus-based solvents in conjunction with a
compound of graphite and aluminum. The new product was reported to be effective, but somewhat
caustic. One of the features is a skimmer device that separates oil from water. The oil joins other
waste oils (see below); the water is added to the tailings line. According to the environmental
assessment, sanitary sewage was to be disposed through septic tanks and leach fields (Newmont
Services, 1987b). During the site visit, Newmont representatives indicated that sanitary sewage is
treated in a settling lagoon and the supernatant added to the tailings line at an average rate of 1.0
gpm. Information on generation rates or ultimate disposal of sludge from the lagoon was not
obtained.
Waste oil is stored in on-site tanks and periodically picked up and transported to a waste oil recycling
facility in California. The oil, which is not a hazardous waste, is manifested in accordance with
California requirements. The frequency and size of shipments were riot determined. One shipment.
on January 1, 1991, involved 6,400 gallons.
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Site Visit Report: Newmont Gold Company Rain Facility
Table 5-10. Selected Wastes and Materials Handled at Rain Facility
Material/Waste
Lubricating and hydraulic
oils, oil from HOTSY
skimmer, antifreeze
Sodium cyanide
Sodium hydroxide
(pelletized)
Lime
Cement
Surfactants
Polymaleic acid antiscalant
Magnesium chloride
Ammonium nitrate/fuel oil
Mill slurry trash
Water from HOTSY steam
cleaner
Solid waste
Sewage effluent and sludge
Amount/Disposition
Transported to waste oil recycling facility in California.
Stored in bins, introduced into mill line at 0.28 Ib/ton of ore, into
barren solution at about 214 pounds/day.
Introduced into mill line at 50 Ib per 3,000 pounds cyanide; into
leach line at about 437 pounds/day.
Stored in bins, added to mill ore at about 1.7 Ib/ton of ore. Also
added to top of heap.
Stored in bin, added to leach ore at 8 Ib/ton of ore.
Stored in drums, added to crushing/grinding circuit at 10
cc/minute.
Stored in bags, added to mill water supply at 24 cc/min, to barren
line at 14 cc/min.
Stored in tank, mixed with water for dust control on roads and
other area.
Used as blasting agent.
Collected at trash screens at about one ton/week, hauled to heap.
Transferred to tailings impoundment.
About 40 cubic yards/week, disposed in onsite trench landfill.
Supernatant from lagoons (one gpm) pumped to tailings
impoundment. Disposition of sewage sludge not determined.
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Site Visit Report: Newmont Gold Company Rain Facility
5.4 REGULATORY REQUIREMENTS AND COMPLIANCE
Prior to operating the Rain mine and mill, multiple permits and approvals were required from State
and Federal agencies. Table 5-11 lists the permits or approvals obtained by Newmont for the Rain
facility organized according to granting agency, type of permit, and the identification number. The
first section below describes major State permits, and is followed by sections on major Federal
approvals.
5.4.1 State of Nevada
This section describes permits issued to the Rain facility by the State of Nevada. The first subsection
describes the new reclamation permit that was obtained by October 1, 1993. This is followed by
subsections that describe water (section 5.4.1.2) and air (5.4.1.3) permits.
5.4.1.1 Reclamation Permit
Nevada Administrative Code 519A.010 to 519A.415 requires facilities active on or after October 1,
1990, to obtain an exploration or mining permit that provides for reclamation. Facilities active on
October 1, 1990, including the Rain facility, had to obtain the permit by October 1, 1993. Permits
have a life-of-mine term and are intended to ensure reclamation is sufficient to return land to a "safe,
stable condition consistent with the establishment of a productive post-mining use of the land and the
safe abandonment of a facility...." (NAC 519A.075). BLM-approved reclamation will satisfy the
State (NAC 519A.255).
Reclamation plans must include, among other things, full descriptions of the affected land and
operations (including roads); nearby waters; proposed productive post-mining use of the land;
schedules for initiation and completion of reclamation activities; and proposed revegetation plans.
State regulations contain requirements for each of these components and provide authority to require
certain types of reclamation (NAC 519A.345). Financial assurance, based on the costs of
reclamation, is required, and the regulations specify the types of surety that are acceptable (NAC
519A.350 to 519A.390). Representatives of Newmont at the time of the site visit indicated that the
company was in the process of preparing the application for this permit.
5.4.1.2 Water Permits
Well and Water Appropriation Permits (one for each of four water wells in Dixie Flats)
According to the environmental assessment, the Rain facility was to require about 525 gpm of new
water for the operation (as noted previously, actual requirements range from about 50 to over 500
gpm, depending on the season). During facility planning, the only nearby sources known to have this
capacity were in the Dixie Flats area, several miles away. Exploratory drilling was conducted to
locate a source closer to the facility but no reliable sources were located. Ultimately, wells in Dixie
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Site Visit Report: Newmont Gold Company Rain Facility
Table 5-11. State and Federal Permits and Approvals, Rain Facility
State
Department of Conservation and Natural Resources, Division of Water Resources;
Well and Water Appropriation (one for each of four
wells)
/
Construction of Tailings Dam
Construction of Pregnant Pond Dam
Permit Numbers 50664, 50665,
50666, and 46346
Permit Number J-261
Permit Number J-276
Department of Wildlife
Industrial Artificial Pond
Permit Number 3435
Department of Conservation and Natural Resources, Division of Environmental Protection
Water Pollution Control
Surface Disturbance (air)
Construction of Primary Crushing Circuit (air)
Construction of Secondary Crushing Circuit (air)
Construction of Portec Cement Bin (air)
Construction of Stanco Projects Lime Bin (air)
Permit Number NEV87011
Permit Number 1321
Permit Number 1617
Permit Number 1618
Permit Number 1619
Permit Number 1748
Division of Health
Operate a Public Water System
Operate a Sewage Treatment System
Permit Number EU-2064-12NC
Permit Number EL 2645
Waste Management Bureau
Class III Landfill
Number not determined
Federal
U.S. Department of Interior, Bureau of Land Management
Rain Plan of Operations, Approved in 1986
Rain Final Environmental Assessment, March 1987
Amendment to the Final Environmental Assessment, Rain Access Road, October 1987
Amendment to the Final Environmental Assessment, Water Pipeline, 1987
Amendment to the Final Environmental Assessment, Powerline, 1987
U.S. Environmental Protection Agency
RCRA Identification Number
NVD 982486300.
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Site Visit Report: Newmont Gold Company Rain Facility
Flats were selected; an amendment to the environmental assessment was prepared for the right-of-way
across public land. The NDEP Division of Water Resources issued Water Appropriation Permits for
wells located in Dixie Flats, six miles east of the Rain facility. Water from these wells is conveyed
by pipeline to the Rain facility. (The permits were not obtained or examined by the site visit team.)
Water Pollution Control Permit
Nevada Revised Statutes (NRS) 445.131 through 445.354 and implementing regulations (Nevada
Administrative Code-NAC) protect ground and surface waters of the State and are implemented by
the Division of Environmental Protection. Regulations specific to the "design, construction, operation
and closure of mining operations" (NAC 445.242 through 243) were added in 1989. Regulatory
requirements are placed on facilities, including the Rain facility, in Water Pollution Control Permits.
The regulations include minimum design and monitoring criteria for various process and waste
components. When no longer active, tailings impoundments must be characterized and covered to
protect wildlife. Spent ore from cyanide leaching must be rinsed until weak acid dissociable (WAD)
cyanide levels in the effluent are less than 0.2 mg/1, the pH is between 6 and 9, and the effluent does
not degrade waters of the State (unless alternative limits are approved).
This permit is the means by which the State has placed requirements on all components of the Rain
facility to protect both ground and surface waters. The Rain facility applied for their Water Pollution
Control permit in December 1986; Permit NEV87011 was issued on April 25, 1988 and remains in
effect for five years (NDEP, 1988). The permit has been revised twice since it was first issued, the
first time in September 1990, the second in January 1991 (NDEP, 1990).
The permit (Section II. C) defines the Rain fluid management system as including the mill and
associated processes and piping, the leach pad and French drains, lined solution ditches, the pregnant
pond and leak detection system, the tailings impoundment and trench drain, the underdrainage
collection system and pond, the seepage collection pond and barrier wall, and the upstream trench
drain (the 1990 and 1991 revisions added the components below the tailings damtrench drains.
seepage collection pond, underdrainage collection pond-to the fluid management system, from which
there may be no discharge to surface waters). The permit requires Rain to ensure the fluid
management system contains all process solutions and the flow from the 100-year, 24-hour storm
event (Section n.A.2). Permit limits include zero discharge to surface waters; for ground water.
releases may not cause violations of drinking water standards or result in WAD cyanide
concentrations over 0.2 mg/1 (Section II.A.3). Other limits include flow limits for the various leak
detection sumps: none may exceed 150 gpd averaged quarterly or 50 gpd averaged annually. In
addition, Newmont must notify the State when static evaluations of waste rock show less than 2<)
percent neutralization capacity; if kinetic tests indicate acid generation, Newmont must propose
methods for containment and evaluate the impact on final stabilization.
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Site Visit Report: Newmont Gold Company Rain Facility
The permit also has required Newmont to submit (and revise) a number of reports and plans,
including an "Emergency Response Plan" and a "Permanent Closure Plan." Besides the monitoring
requirements described below, the permit also requires annual reports on water supply analytical
results; spill and release synopses; summaries of operations; effectiveness of seepage pond and
upstream trench drain; and summary reports on the downstream trench drain system.
The Water Pollution Control Permit for the Rairt facility contains extensive monitoring and reporting
requirements. It stipulates the location, frequency, and parameters to be monitored. NDEQ updated
specific conditions for the facility when the permit was revised in January 1991. Monitoring
requirements include a variety of parameters grouped by Profile. Profile I consists of the standard
drinking water parameters. Profile II is a list of 40 elements, metals and compounds selected by the
NDEQ; some of these overlap with those required by Profile I. Table 5-12 presents the monitoring
requirements (including locations, parameters, and frequencies) in Permit NEV87011 as of January
1991; monitoring locations are identified in Figure 5-2.
Monitoring requirements have been modified as facility operations have changed since permit
issuance. For example, construction of the upstream trench drain lead to the abandonment of
monitoring wells 2, 7, 8, 9,10, 11, 12, 13, 17, and 18. Monitoring requirements also changed to
address problems with specific facility units in the fluid management system such as the waste rock
pile and tailings impoundment. For example, monitoring wells 2b, 3, 16, and 23 were included in
the permit to monitor seepage. Similarly, weekly flow and quarterly analysis of Profile I constituents
from the seepage collection pond and trench drains below the tailings dam are now required. The
permit also provides that Newmont may request a reduction in the number of elements and frequency
of analysis after one year of complete monitoring, based on justification other than cost.
Specific monitoring data for the waste rock, pregnant and barren solutions, and tailings and reclaim
water are presented in the preceding discussions of those topics. Table 5-13 is a summary of
monitoring data for the French drains, pregnant pond, underdrain collection pond, and the upper and
lower trench drains for the four quarters ending August 1991, as provided in the Quarterly
Monitoring Reports. As available, pH and cyanide as free or WAD are included for each discharge
point. .Water from these sources is returned to the tailings impoundment.
5.4.1.3 Air Permits
The Rain facility was granted Point Source Paniculate Permits under the authority of Nevada Revised
Statutes (445.401 - 445.601) and Administrative Codes (445.430 - 445.846). As part of the
construction permit for the primary and secondary crushing circuit, the Rain facility applies water and
surfactant at the points of dust generation. These include the jaw feeder, the intake to the jaw
crusher, the point where cement is added, and at the conveyor belt drop point from the radial stacker
Sprays are also located at the discharge belt from the cone crusher and the final drop point to the
stockpile. The dust suppression system is inspected Annual I > by Bureau personnel. In the
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Site Visit Report: Newmont Gold Company Rain Facility
Table 5-12. Permit NEV87011: Monitoring Locations, Parameters, and Frequencies
Monitoring Location
Water Supply
Monitoring wells MW2B, MW-3, MW-
16, MW-23
Leach Pad French Drains:
East Drain and West Drain
Leak Detection Sumps (fluid cap.):
Pregnant Pond (30 gal.)
Underdrain Collection Pond (30 gal.)
Waste Rock/Overburden
generated during the quarter
Pregnant & Barren Leach Solution
Tails Water (TW), Reclaim Water (RW),
Underdrainage Water (UW)
Seepage Pond (CP)
Upstream Trench Drain UTD)
Downstream Trench Drain (DTD)
Parameter
Profile I1
Profile I
Average Flow (gpd), pH, Free CN
Profile I
Average Daily
accumulation (gpd)
Meteoric Water Mobility Analysis
and Acid generation-acid
neutralization potential
Profile II2
Profile II
Profile I
Pumpback flow
Profile I
Pumpback flow
Profile I
Pumpback Flow
Frequency
Annually
Quarterly
Weekly
Quarterly
Weekly
Quarterly
Quarterly
Quarterly
Quarterly
Weekly
Quarterly
Weekly
Quarterly
Weekly
1. Profile I includes:
Alkalinity
Arsenic
Barium
Cadmium
2. Profile n includes all the constituents of Profile I and the following:
Aluminum Bismuth Gallium Manganese
Antimony Calcium Lanthanum Molybdenum
Beryllium Cobalt Lithium Nickel
Chloride
Chromium
Copper
Fluoride
Iron
Lead
Magnesium
Mercury
Nitrate
PH
Potassium
Selenium
Silver
Sodium
Sulfate
TDS
Phosphorus
Scandium
Strontium
WAD cyanide
Zinc
Thallium
Tin
Titanium
Vanadium
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Site Visit Report: Newmont Gold Company Rain Facility
Table 5-13. Discharges from Monitoring Locations Reported in Quarterly Monitoring Reports
Monitoring Location
West French Drain
Flow (gpm)
pH (ave.)
CN (free)
East French Drain
Flow (gpm)
pH (ave.)
CN (free)
Pregnant Pond PPS Flow (gpm)
Underdrainage SW Flow (gpm)
Seepage Pond CP Flow (gpm)
Upper Trench Drain UTD
Flow (gpm)
pH (ave.)
CN (WAD)
Lower Trench Drain DTD
Flow (gpm)
pH (ave.)
CN(WAD)
4th, 1990
O(dry)
n
n
O(dry)
it
n
NA
NA
NA
0.81
7.2
0.510
1.55
7.4
0.320
1st, 1991
0.05
8.0
<0.1
0.04
7.5
0.1
0.857
0.000
7.83
2.24
7.0
0.072
1.91
7.4
0.110
2nd, 1991
2.02
7.8
<0.1
0.64
7.5
<0.1
0.464
0.000
21.10
0.95
7.45
0.050
3.12
5.8
0.005
3rd, 1991
1.9
7.3
<0.1
1.87
7.6
<0.1
0.050
0.000.
5.96
0.57
7.2
0.040
0.13
7.3
0.020
(Source: Quarterly Reports supplied by the State of Nevada and the Rain facility)
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Site Visit Report: Newmont Gold Company Rain Facility
information available, no mention was made of the baghouses used to control dust from the cement
and lime storage bins.
5.4.2 Plan of Operations (Bureau of Land Management)
A portion of the Rain facility is located on public land managed by the Bureau of Land Management
(BLM). In compliance with the National Environmental Policy Act (NEPA), Newmont Services Ltd.
completed a draft environmental assessment (EA) for the Rain Project in December 1986 under the
direction of BLM. The draft EA was revised and a final EA was issued in March 1987. The Elko
District Manager for BLM signed a Decision Notice and Finding of No Significant Impact for the
Rain proposal on May 8, 1987. The only conditions set forth in BLM's Decision were specific waste
dump reclamation issues and those specified in Newmont's Plan of Operations (U.S. Department of
Interior, 1987; Newmont Services, 1987b).
\
For mining facilities that disturb more than 5 acres of land the BLM requires the owner to submit a
Plan of Operations. The BLM approved Newmont's Plan in 1986; a copy of the Plan was submitted
with the Final EA in 1987. The Plan is a brief statement describing the size of the facility, estimates
of material to be moved, a description of the mill and leach circuit, environmental protection
measures to be followed, and reclamation activities. Also included are Process Design Criteria and
Flow Diagrams.
Because no portions of the site on BLM lands involve cyanide operations (only portions of the waste
rock dump and roads are on BLM lands), BLM's 1990 cyanide policy is not applied to the site. (The
BLM policy incorporates Nevada regulations on water pollution control, protection of wildlife, and
reclamation. The only substantive difference, were Rain's cyanide operation on BLM land, would be
a quarterly inspection by BLM.) In addition, BLM policy requiring full bonding will defer to the
State's bonding requirement, which is due to be fully implemented at the Rain facility in 1993.
5.4.3 Hazardous Waste (U.S. Environmental Protection Agency)
The Environmental Protection Agency has assigned a RCRA identification number to the Rain facility
since they are (or were) a small-quantity generator of petroleum-based cleaning solvents which were
used as part of operations and maintenance. Safety-Kleen transported these spent solvents off-site (for
regeneration). This service has been discontinued; it was replaced with the HOTSY steam cleaning
process described in Section 5.3.5.
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Site Visit Report: Newmont Gold Company Rain Facility
5.5 REFERENCES
Bonham, H.F., Jr. 1988, "Bulk Minable Gold Deposits of the Western United States", In: The
Geology of Gold Deposits: The Perspective in 1988", R.R. Keays, W.R. Ramsay, D.I. Groves,
Editors. Economic Geology Monograph 6.
Knight Piesold and Co. 1990 (June 8). "Newmont Gold Company Mill No. 3 Project - Tailings
Storage Facility Expansion Program - Final Design Report." Prepared for Newmont Gold
Company.
Nevada Division of Environmental Protection. 1988a (January). Fact Sheet (pursuant to NAC
445.148), Water Pollution Control Permit NEV87011.
Nevada Division of Environmental Protection. 1988b (April 25). Water Pollution Control Permit
NEV87011 issued to Newmont Gold Company. (Subsequently modified and reissued on
September 20, 1990; further modified January 8, 1991-see NDEP, 1990.)
Nevada Division of Environmental Protection. 1989 (February 3). Finding of Alleged Violation and
Order under Water Pollution Control Permit NEV87011.
Nevada Division of Environmental Protection. 1990 (September 5). Water Pollution Control Permit
NEV87011 issued to Newmont Gold Company (revisions to 1988 permit). Includes revisions
dated January 8, 1991.
Newmont Gold Company. 1987 (April 20). Application for a Water Pollution Control Permit -
Short Form M. Submitted to Nevada Division of Environmental Protection (shows receipt of
February 27, 1987-prior to applicant's signature date).
i
Newmont Gold Company. 1988a (January 14). Letter from D.A. Deming, NGC, to P. Liebendorf,
Nevada Division of Environmental Protection. Subject: Suggested language for draft permit.
Newmont Gold Company. 1988b. "Rain Project Spill Emergency Response Plan." Submitted to
Nevada Division of Environmental Protection on August 17, 1988. (See also Newmont, 1990,
for Emergency Response Plan for Environmental Releases.)
Newmont Gold Company. 1988c. "Rain Project Closure Plan." Submitted to Nevada Division of
Environmental Protection on August 17, 1988.
Newmont Gold Company. 1988d (August 30). Letter to Paul Liebendorfer (NDEP) from Steve Botts
concerning the release of sodium cyanide and tailings slurries on August 19 due to a plug in the
tailings line.
Newmont Gold Company. 1988e (November 22). Letter to Paul Liebendorfer (NDEP) from Ann
Tyson concerning summary of remedial action taken by Newmont to contain tailings seepage.
Newmont Gold Company. 1988f (December 14). Letter from A.M. Tyson, NGC, to P.
Liebendorfer, Nevada Department of Environmental Protection. Re: Rain Permit, NEV87011
(Sampling results for monitoring system downstream of tailings and proposed modification to
permit NEV87011.)
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Site Visit Report: Newmont Gold Company Rain Facility
Newmont Gold Company. 1988g (December 21). Letter from A.M. Tyson, NGC, to P.
Liebendorfer, Nevada Department of Environmental Protection. Re: Pregnant Pond Sump
Discharge; Rain Permit NEV87011.
Newmont Gold Company. 1989a (January 5). Letter from A.M. Tyson, NGC, to P. Liebendorfer,
Nevada Department of Environmental Protection. Subject: Status report on (I) Pregnant liquor
detection in recovery system, (II and IV) tailings dam recovery system, status report and
monthly monitoring results
Newmont Gold Company. 1989b (February 1). Letter from A.M. Tyson, NGC, to P. Liebendorfer,
Nevada Department of Environmental Protection. Re: Rain Project Status; NEV87011 (Status
report on leach pad/pregnant pond action, tailings impoundment collection system).
Newmont Gold Company. 1989c (February 15). Letter from A.M. Tyson, NGC, to P.
Liebendorfer, Nevada Department of Environmental Protection. Re: Rain Project; NEV87011
(Response and to NDEP Finding of Alleged Violation and Orderdescription of remedial actions
taken).
Newmont Gold Company. 1989d (March 23). Letter from A.M. Tyson, NGC, to P. Liebendorfer,
Nevada Division of Environmental Protection., Re: Rain Remedial Action; nev87011 (status
report on tailings remediation: construction of trench drains and associated monitoring wells
downstream of seepage collection pond)..
Newmont Gold Company. 1989e (April 14). Letter from A.M. Tyson, NGC, to P. Liebendorfer,
Nevada Division of Environmental Protection. Re: Rain Remediation Action; NEV87011
(status report on tailings remediation: trench drains and associated monitoring wells).
Newmont Gold Company. 1989f (July 31). "Rain Project Tailings Impoundment Remediation."
(Chronology and sampling data)
Newmont Gold Company. 1990a (April 23). "Newmont Gold Company Rain Fluid Management
System Best Management Plan." Proposed plan submitted with letter from D. Baker, NGC, to
P. Liebendorfer, Nevada Department of Environmental Protection.
Newmont Gold Company. 1990b (June 28). Letter to Tom Fronapfel (NDEP) from David Baker
concerning response to AMD NOV.
Newmont Gold Company. 1990c (October). "Rain Emergency Response Plan for Environmental
Releases." Submitted to Nevada Division of Environmental Protection.
Newmont Gold Company. 1990d (December). Tentative Permanent Closure Plan. Prepared by
' Newmont Gold Company, Department of Environmental Affairs.
Newmont Gold Company. 1990e (December). Response to Nevada Bureau of Air Quality Notice of
Alleged Violation No. 830, Rain Operation. Note: State NOV letter not on file with NDEQ.
Newmont Gold Company. 1991a (January 15). Letter from E. Hamer, NGC, to T. Fronapfel,
Nevada Division of Environmental Protection. Subject: Fourth quarter 1990 monitoring report
and status report.
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Site Visit Report: Newmont Gold Company Rain Facility
Newmont Gold Company. 1991b (September). Letter from David Baker, NGC, to Stephen
Hoffman, Environmental Protection Agency. Re: transfer of following documents requested
during the Site Visit: (1) block diagrams of the mine, mill, heap leach, and tailings processes;
(2) Air Quality Permit Summary as of August 1991; (3) site map with elevation contours; (4)
estimated uncompacted garbage production; (5) wildlife mortality reports dating back to 1988;
(6) sewage flow rates.
Newmont Services Ltd. 1987a (February 11). Letter from N. Greenwald, Newmont, to H. Van
Drielen, Nevada Division of Environmental Protection. Subject: Request for issuance of
groundwater protection permit and submission of supporting documents (sections of draft
environmental assessment, plan of operations, reports on geotechnical investigations for leach
pad and tailings impoundment.
Newmont Services Ltd. 1987b (March). Final Environmental Assessment, Rain Project and
Amendments for the Access Road, Power Line, and Water Supply Line. Prepared by Newmont
Services, Tucson, Arizona.
Steffen Robertson and Kirsten. 1990 (October). Rain Project Solution Collection and Return System
Design Report. Prepared for Newmont Gold Company by Steffen Robertson and Kirsten
(U.S.), Inc., Lakewood, Colorado.
U.S. Department of the Interior, Bureau of Land Management, Elko District Office. 1988
(December 27). Letter from L. Sweeney, BOM, to L. Dodgion, Nevada Division of
Environmental Protection. Subject: Request for meeting on Rain facility tailings impoundment
leaks.
U.S. Department of the Interior. 1987c (June 3). Letter to Joy McBeth (Newmont) from Tim
Hartzell (Elko District Manager, BLM) concerning 1) water rights to local springs, and 2)
Decision Notice and Finding of No Significant Impact.
U.S. Environmental Protection Agency. 1991 (August). Telephone Checklist: Newmont Gold
Company, Rain Mine. Completed August 16, 1991, with David Baker, Vice President for
Environmental Affairs and Steve Hoffman, EPA Office of Solid Waste.
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Site Visit Report: Newmont Gold Company Rain Facility
APPENDIX 5-A
FLOW CHARTS OF THE RAIN MINE, MILL, HEAP LEACH, AND TAILINGS PROCESSES
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Site Visit Report: Newmont Gold Company Rain Facility
MINE
5.500 tpd
29,500 tpd
3,180 tpd
FLOWS:
23J gpn AVO.
183 gpm nuz.
TO TJUU1IO
MHLIHE
Figure 5-10. Flowchart of the Rain Mine
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Site Visit Report: Newmont Gold Company Rain Facility
MILL 3 PROCESS
Surfactant
lOcc/mln
CMUSKD
OKI
STOCKPILE
^
EMHICENCT
cmnHED
OKI
sroeiinu
<«-MMM.)
Note: Aversfcand
p*aki ara lltud.
Figure 5-11. Flowchart of the Rain Mine Mill 3 Process
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Site Visit Report: Newmont Gold Company Rain Facility
HEAP LEACH PROCESS
RUN OF
MINX
THICK
HAUL
3J7I TK>. MOO WD
«I7>
HI TFO
1.000 TFD
ftmcfc Drain
O.M om. ioj cnm
Cut DtMeh Dnin
cm. «j CFM
MILL BUILDING
Note:
ad
i*
Figure 5-12. Flowchart of the Heap Leach Process
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, Site Visit Report: Newmont Gold Company Rain Facility
TAILING PROCESS
Leak Detection
Oflow
AMD
COLLECTION
POND
PUMP
520 gpm
1000 gpm
2,306 tpd solids
3,833 tpd solution
RECLAIM
SOLUTION
FRENCH
DRAIN
UNDERDRAW
SEEPAGE
POND
i » COLLECTI
32,309 g/d
109,300 g/d
No flows
are taken
UTD
CUTOFF
TRENCH
2,166 g/d
6,320 g/d
DTD
CUTOFF
TRENCH
3,017 g/d
17,830 g/d
Note: Average and
peaks are listed
Figure 5-13. Flowchart of the Rain Mine Tailing Process
5-56
-------
Site Visit Report: Newmont Gold Company Rain Facility
APPENDIX 5-B
CHEMICAL ANALYSIS OF FIVE SITES ALONG EMIGRANT SPRINGS
5-57
-------
Site Visit Report: Newmont Gold Company Rain Facility
*' ft 1 $'
- . x..-'#rr
I
o
5
o
i
1
5-58
-------
Site Visit Report: Newmont Gold Company Rain Facility
Table 5-14. Acid Rock Drainage Sampled Below Waste Rock Dump, Sample Location 1,
Rain Facility, May and July, 1990
Sample Location
Emigrant 1
Parameter
pH
WAD
Arsenic
Barium
Cadmium
Chromium
Copper
Lead
Mercury
Selenium
Silver
Zinc
Dates Sampled
(all values in ppm)
5-90
2.67/2.37
< 0.005
46.07 14/ 28
0.27/ < 0.05/0. 18
0.57/ 0.23/ 0.39
1.6/0.56/0.84
27.0/ 10/ 18
< 0.005
0.14/0.005/0.009
0.017/.01/.013
<0.05
13/ 8.3/10.6
7-90
2.63/2.88
15/ 147 15
0.23
0.36
0.72/0.69/0.71
14
< 0.005
.0019/.0016/.0018
.011/.010/.011
< 0.005
5.8/5.7/5.8
All values are shown as [High]/[Low]/[Mean] for the month for each parameter with at least one value
above detection reported during the month. If samples did not reveal concentrations above detection, the
detection limit is shown. If only one sample was taken, the value detected is shown.
The pH values are shown as High/Low for the month.
Data Source: Rain Project Solution Collection and Return Design Report, 1990
5-59
-------
Sire Visit Report: Newmont Gold Company Rain Facility
Table 5-15. Acid Rock Drainage Sampled Below Waste Rock Dump, Sample Location 2,
Rain Faculty, May and July, 1990
Sample Location
Emigrant!
Parameter
pH
WAD
Arsenic
Barium
Cadmium
Chromium
Copper
Lead
Mercury
Selenium
Silver
Zinc
Dates Sampled
(all values in ppm)
5-90
4.43/3.13
_
0.60/ 0.013/ 0.41
0.30/ 0.09/ 0.22 '
0.042/0.011/0.026
0.068 < 0.005/0.045
1.4/0.21/0.68
< 0.005
.0006/.0001/.0003
0.016/0.013/0.015
< 0.005
1 .41 0.28/ 0.89
All values are shown as [High]/[Low]/[Mean] for the month for each parameter with at least one value
above detection reported during the month. If samples did not reveal concentrations above detectioh, the
detection limit is shown. If only one sample was taken, the value detected is shown.
The pH values are shown as High/Low for the month.
Data Source: Rain Project Solution Collection and Return Design Report, 1990
5-60
-------
Site Visit Report: Newmont Gold Company Rain Facility
Table 5-16. Surface Water Quality Data in Emigrant Springs, May and July, 1990
Sample Location
Emigrant 3
Parameter
pH
WAD
Arsenic
Barium
Cadmium
Chromium
Copper
Lead
Mercury
Selenium
Silver
Zinc
Dates Sampled
(all values in ppm)
5-90
7.747 6,71
0.48/< 0.005/0. 17
0.84/0.25/0.47
0.007/<0.005/.004
.027/<0.005/.010
.18/.008/.053
.008/<0.005/.004
.0011/<0.0001/.0004
0.007/< 0.005/0.004
< 0.005
0.18/<0.005/.008
7-90
7.60/ 7.40
.
.013/<0.0001/.007
0.51/ 0.48/ 0.50
< 0.005
< 0.005
0.012/<0.005/.007
< 0.005
< 0.005
< 0.005
< 0.005
.014/<0.005/.008
All values are shown as [High]/[Low]/[Mean] for the month for each parameter with at least one value
above detection reported during the month. If samples did not reveal concentrations above detection, the
detection limit is shown. If only one sample was taken, the value detected is shown.
The pH values are shown as High/Low for the month.
Data Source: Rain Project Solution Collection and Return Design Report, 1990
5-61
-------
Site Visit Report: Newmont Gold Company Rain Facility
Table 5-17. Surface Water Quality Data in Emigrant Springs Below EMIG-3,
May and July, 1990
Sample Location
Emigrant 4
Parameter
PH
WAD
Arsenic
Barium
Cadmium
Calcium
Chromium
Copper
Lead
Mercury
Selenium
Silver
Zinc
Dates Sampled
(all values in ppm)
5-90
8.43/7.20
\
0.10/.007/.046
0.62/0.11/0.34
< 0.005
.013/<0.005/.007
.047/.008/.03
.009/<0.005/.006
.0005/<0.0001/.0003
.005/<0.005/.003
< 0.005
.08/<0.005/.043
7-90
8.39/8.39
~
~
All values are shown as [High]/[Low]/[Mean] for the month for each parameter with at least one value
above detection reported during the month. If samples did not reveal concentrations above detection, the
detection limit is shown. If only one sample was taken, the value detected is shown.
The pH values are shown as High/Low for the month.
Data Source: Rain Project Solution Collection and Return Design Report, 1990
5-62
-------
Site Visit Report: Newmont Gold Company Rain Facility
Table 5-18. Surface Water Quality Data Below EMIG-3, May and July, 1990
Sample Location
Emigrants
Parameter
pH
WAD
Arsenic
Barium
Cadmium
Chromium
Copper
Lead
Mercury
Selenium
Silver
Zinc
Dates Sampled
(all values in ppm)
5-90
8.74/7.72
._
.023/.007/.045
0.18/0.16/0.17
< 0.005
< 0.005
.018/<0.005/.009
< 0.005
<0.0001
< 0.005
< 0.005
< 0.005
7-90
8.73/8.64
All values are shown as [High]/[Low]/[Mean] for the month for each parameter with at least one value
above detection reported during the month. If samples did not reveal concentrations above detection, the
detection limit is shown. If only one sample was taken, the value detected is shown.
The pH values are shown as High/Low for the month.
Data Source: Rain Project Solution Collection and Return Design Report, 1990
5-63
-------
Site Visit Report: Newmont Gold Company Rain Facility
Table 5-19. Water Quality and Sediment Data, Rain Facility, June 15, 1990
Parameter
pH
AS
BA
CD
CR
CO
HG
PB
SE
ZN
EMIG1
3.21
1100
350
H
35
160
4.6
30
<5
110
EMIG IB
3.65
< 0.005
<0.05
0.029
0.024
0.82
<0.0001
<0.005
0.005
1.5
EMIG 2
6.68
0.014
0.36
< 0.005
< 0.005
0.01
0.0003
<0.005
< 0.005
0.015
EMIG2A
-
120
1800
2.0
40
54
3.2
26
<5
130
EMIG2B
-
36
440
1.9
43
23
<0.10
19
<5
110
EMIG 3
7.42
0.076
1.3
< 0.005
0.008
0.015
0.0001
< 0.005
0.009
0.14
Parameter
pH
AS
BA
CD
CR
CU
HG
PB
SE
ZN
EMIG 4
7.90
120
790
2.1
33
87
0.47
20
<5
120
EMIG4A
-
-
680
<0.5
44
38
0.17
18
<5
130
EMIG 6
-
48
870
1.1
26
120
0.33
25
<5
160
EMIG6A
-
67
1400
1.2
20
31
0.36
25
<5
130
EMIG6B
-
74
260
1.0
20
28
0.10
23
<5
130
EMIG 1, IB, 2, 2A, 2B: Represent samples of acid mine drainage, not in Emigrant Springs but in drainage channel
upstream of Emigrant Springs, below the waste rock dump.
EMIG 3: Represent a sample of the confluence of the acid drainage flow and Emigrant Spring.
EMIG 4, 4A, 6, 6A, 6B: Represent solid samples from stream beds of Emigrant Springs, except pH in EMIG 4,
which is liquid flow.
If samples did not reveal concentrations above detection, the detection limit is shown.
Data Source: Rain Project Solution Collection and Return Design Report, 1990
5-64
-------
Site Visit Report: Newmont Gold Company Rain Facility
APPENDIX 5-C
CHEMICAL ANALYSIS OF METEORIC WATER MOBILITY TEST FOR
THE THIRD AND FOURTH QUARTERS OF 1990, AND THE FIRST QUARTER OF 1991
5-65
-------
Site Visit Report: Newmont Gold Company Rain Facility
[Appendix not reproduced for this electronic version. Copies may be
obtained from U.S. EPA, Office of Solid Wastes, Special Waste
Branch.]
5-66
-------
Site Visit Report: Newmont Gold Company Rain Facility
APPENDIX 5-D
QUARTERLY MONITORING DATA FOR 1988 AND 1989 FOR SELECTED
MONITORING WELLS AND THE SEEPAGE COLLECTION POND
5-67
-------
oo
Table 5-20. Monthly Average for Selected Sample Results, Rain Facility, 1988'
Sample
Location
MW-2
MW-3
Parameter
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
7/88
7.02/7.48
' 205
<.005 n = 2
0.0 n = 3
..
-
-
__
..
8/88
6.9/7.45
224
_.
0.0 n = 4
..
--
-
..
'
9/88
6.74
205
_,
0.0 n=1
_
-
--
._
..
10/88
-
-
_
..
6.12/6.7
692
I.006..17..064) n = 3
<.02 n=1
_
1 1/88
6.66/11.76
250
<.005 n = 5
<.02 n = 3
(.003..033..016) n = 4
..
5.04/6.77
785
K.005,.093,.049) n = 4
<.02 n = 2
(.018,. 457,. 15) n-4
--
12/88
6.59/7.28
223
<.005 n = 3
.12 n = 1
< .02 n = 1
<.05 ri=1
«. 005,1. 7..571 n = 3
..
6.0/7.3
538
(.046.6.1.1.71) n = 4
8.8 n = 1
5.3 n=1
7.0 n = 1
(.134.4.8.1.57) n = 3
..
i
1 1 . The pH values are given as Low/High for the month. 2. Electrical conductivity (EC) values are given as the average of reported values
for the month. 3. Cyanide values are shown as (Low, High, Mean) for each laboratory reporting at least one result above test detection limits
during that month. If analysis was performed with no concentrations above detection the test detection limit is shown. The "n" value on the
fit-In of a cell indicates the number of samples performed by a lab during that month.
Sire Visit Report: Newmont Gold Company Rain Facility
-------
Table 5-20. Monthly Average for Selected Sample Results, Rain Facility, 1988 (continued)
in
Sample
Location
MW-4
MW-S
RAIN
SEEPAGE .
COLLECTION
POND
Parameter
pH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
pH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
pH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
7/88
--
-
f
~
--
_
-
6.17
311
_
-
--
8/88
-
~
~
..
_,
..
..
7.27/7.46
361
-
-
9/88
-
--
__
-
"
__
.
6.3
410
--
-
10/88
--
--
--
-
6.0/6.8
724
«.005,.03,.013) n = 3
0.0 n = 2
<.02 n = 1
-
6.43/6.75
735
(1.5,11.6,5.6) n = 3
<.3 n = 3
-
11/88
5.61/6.51
1505
«.005,.005,.004) n = 5
0.0 n = 3
<.02 n = 3
<.005 n = 4
..
6.71/7.39
752
«.005,.03,.017| n = 4
«.02,.02,.017) n = 3
«.005,.083,.042) n = 4
-
6.84/7.15
859
(11,18,14.3) n = 3
(11,18,13.7) n = 3
(10,30,20) n = 2
-
12/88
6.03/6.18
1233
<.005 n = 2
<.025 n = 1
<.02 n = 1
c.025 n = 1
(<.005,.115,.059| n = 2
..
-
-
..
..
--
6.58/7.19
922
(20,45,30.3) n = 3
63.0 n=1
42.0 n = 1
51.0 n = 1
(18.5,39.0,28) n = 3
--
a-
i
I
a
£
£
a
I
-------
Table 5-21. Monthly Average for Selected Sample Results, Rain Facility, 19892
Sample
Location
MW-2
j
MW2I
MW-3
Parameter
PH .
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
pH
EC
Cyanide
WAD
Cv»ntde
F.ee
Cyanide
tot
pH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
1/89
6.0/6.65
229
<.005 n = 3
|.12.2.0,.75) n = 3
<.02 n = 3
(.05, .16,. 10) n = 3
«.005,.112,.04) n = 3
6.48/7.2
847
(9.3,13.4,11.1) n = 3
(14,18,16) n = 3
(8.9.13.1,10.6) n = 3
(11,16,13.7) n = 3
(10.8,11.9,34.5) n = 3
-
2/89
6.75/6.77
218
«.02,.3,.11) n = 4
«.005,.041,.016) n = 3
«.02,1.1,.31) n = 4
6.56/7.43
603
(.03,29.9,8.16) n = 4
(.161,24.4,6.67) n = 5
(.1,34.8,10.15) n = 4
3/89
6.76/6.94
204
<.02 n = 2
«.015,.022,.011)
n = 4
<.02 n = 4
7.13/7.27
455
(.03,8.5,2.9) n = 3
(.026,12.54,6.5) n = 3
.05,9.7,3.3) n = 3
4/89
6.98/7.36
170
<.02 n = 2
<.015 n = 2
<.02 n = 2
6.86/7.07
454
<.02 n = 2
<.015 n = 2
.04,.29,.17h = 2
5/89
i
8.41
1370
.1 n = 1
.059 n=1
.10 n = 1
--
--
.09 n = 1
<.015 n = 1
07 n = 1
6/89
7.62
927
<.02 n = 1
<.02 n = 1
6.95
593
<.02 n=1
<.015 n = 1
1 n=1
7/89
7.83
407
<.02 n = 1
.03 n = 1
6.69
572
<.02 n = 1
-
I
I
1. The pH values are given as Low/High for the month. 2. Electrical conductivity (EC) values are given as the average of reported values for the month. 3. Cyanide values are
shown as (Low, High. Mean) for each laboratory reporting at least one result above test detection limits during that month. If analysis was performed with no concentrations above detection
then the test detection limit is shown. The "n" value on the right of a cell indicates the number of samples performed by a lab during that month.
-------
Table 5-21. Monthly Average for Selected Sample Results, Rain Facility, 1989 (continued)
Sample
Location
MW-4
MWft
MW-6
MW-7
Parameter
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
PH
EC
Cyanide
WAD
Cyanide
Fiee
Cyanide
tot
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
1/89
6.09/6.51
1252
<.005 n = 3
(.11, .18,. 147) n = 3
<.02 n = 3
«.01,.07,.045) n = 3
«.015,.08,048) n = 3
..
-
-
..
Dry
-
-
..
--
2/89
5.51/6.55
798
«.02,.09,.03) n = 4
«.015,.007,.006) n=4
«.02,.08,.03| n = 4
6.82
545
«.02,.08,.028» n = 5
|.015..021,.01) n = 4
|.03,.3,.116) n = 5
--
9.95/10.53
382
|.01,.08,.063) n = 4
«.015,.03,.016) n = 4
(.2,1.0,.416) n = 4
3/89
6.21/6.42
782
<.02 n = 4
<.015 n = 4
«.02,.08,.03) n = 4
7.14/7.48
344
«.02,.03,.017) n = 3
<.015 n = 3
«.02,.1,.05) n = 3
Dry
8.57/10.3
489
(.08,. 13,. 103) n = 3
<.015 n = 3
(.28,.43,.337) n = 3
4/89
6.30/6.34
758
<.02 n = 2
<.015 n = 2
<.02 n = 2
6.84/7.0
385
<.02 n = 2
<.015 n = 2
<.02 n = 2
Dry
Abandoned
--
__
--
5/89
6.31
805
<.02 n=1
<.015 n=1
<.02 n=1
6.61
443
<.02 n = 1
<.015 n = 1
<.02 n = 1
Dry
--
6/89
6.56
820
<.02 n = 1
<.02 n = 1
6.69
491
<.02 n = 1
<.02 n = 1
Dry
-
..
--
7/89
6.55
719
<.02 n = 1
<.02 n = 1
6.58
542
<.02 n=1
-
<.02 n=1
Dry
-
..
'
-
-------
Table 5-21. Monthly Average for Selected Sample Results, Rain Facility, 1989 (continued)
-i
K)
Sample
Location
MW-ft
MW-9
MW-10
MW-11
Parameter
pH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
pH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
1/89
.
-
w
_
.
-
..
__
-
--
-
2/89
Dry
9.02
468
<.02 n = 2
(.007,.029,.018| n = 2
«.02,.03,.02) n = 2
7.41/8.12
806
(6.7.21.8,13.7) n = 3
(8.06.15.5,12.8) n = 4
(9.9,22.4.16.2) n = 3
9.66
424
(.06,.2,.12) n = 3
(.013..172..07) n = 3
|.01,.03,.23| n = 3
3/89
Dry
8.36/9.2
665
K.02,.03,.015) n=4
<.015 n = 2
«.02,.04..023) n = 4
7.54/7.61
540
(.09, .24.. 158) n = 4
(.07..444..183) n = 4
(.25,1.1, .46) n = 4
8.58/8.78
377
«.02..07..03) n = 3
«.015,.029,.015) n = 3
(.02..13..06) n = 3
4/89
Dry
8.73
978
<.02 n = 1
<.015 n = 2
.08 n = 1
7.44
531
.03 n = 1
<.015 n = 1
.14 n = 1
8.5
372
<.02 n = 1
<.015 n = 1
<.02 n = 1
5/89
Abandoned
Abandoned
Abandoned
Abandoned
6/89
'
7/89
I
I
e
a
I
-------
Table 5-21. Monthly Average for Selected Sample Results, Rain Facility, 1989 (continued)
OJ
Sample
Location
MW-12
MW-13
MW14
MW-1S
MW-16
Parameter
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
PH
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
1/89
2/89
Dry
Dry
--
-
,_
<.02 n = 1
Dry
8.3
1530
<.02 n = 1
<.015 n=1
< .02 n = 1
3/89
8.62
357
<.02 n = 1
<.015 n = 1
<.02 n=1
Dry
7.69
330
<.02 n=1
<.02 n=1
Dry
7.7
832
<.02 n = 2
<.015 n = 2
<.02 n = 2
4/89
8.85
370
<.02 n = 1
<.015 n = 1
<.02 n=1
Dry
-
-
<.02 n=1
<.015 n=1
<.02 n = 1
Dry
7.73/7.93
566
<.02 n=1
<.015 n = 2
<.02 n = 1
5/89
Abandoned
Abandoned
7.60
197
<.02 n=1
<.015 n = 1
<.02 n = 1
Abandoned
7.68
468
<.02 n = 1
<.015 n = 1
<.02 n = 1
6/89
7.76
192
<.02 n=1
< .02 n = 1
7.75
535
<.02 n = 1
<.02 n=±1
7/89
8.25
177
<.02 n=1
._
<.02 n=1
Dry
!
a
l
a.
£
-------
Table 5-21. Monthly Average for Selected Sample Results, Rain Facility, 1989 (continued)
Sample
Location
MW-17
MW-18
MW-19
MW-20
MW-21
Parameter
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
PH
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
1/89
2/89
-
--
--
~
..
--
-
-
..
..
-
-
--
-
..
..
--
3/89
--
Dry
-
-
__
-
--
-
-
..
-
4/89
Dry
7.63
294
C.02 n = 1
<.015 n = 1
<.02 n=1
Dry
Dry
7.8
725
..
<.015 n = 1
--
5/89
Abandoned
Abandoned
Dry
Dry
7.43
851
<.02 n = 1
085 n=1
<.02 n=1
6/89
7.9
652
<.02 n = 1
_
<.02 n = 1
Dry
7.85
769
<.02 n = 1
<.02 n = 1
7/89
Dry
*
Dry
7.3
601
<.02 n = 1
..
<.02 n = 1
I
I
3
3
I
I
-------
Table 5-21. Monthly Average for Selected Sample Results, Rain Facility, 1989 (continued)
Sample
Location
MW-22
MW-23 .
SEEPAGE
COLLEC-
TION
POND
RAIN
SEEPAGE
COLLEC-
TION
POND
TRENCH
DRAIN
Parameter
pH
pH
EC
Cyanide
WAD
Cyanide
Free
- Cyanide
tot
pH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
1/89
6.73/7.18
968
(15,34,22.7) n = 3
(24,34,30.7) n = 3
(15,27,20) n = 3
(27,37,32) n = 3
(23,36.277) n = 3
Dry
2/89
-
-
'
..
7.41/7.62
783
(2.7,20.8,12.1) n = 3
(6.9,20.2,14.6) n = 4
(6.9,18.5,12.9) n = 3
--
-
-
--
--
3/89
-
-
_.
7.4/7.8
669
(1.5,6.6,4.8) n = 3
(1.2,7.2,4.8) n = 3
(2.4,7.8,5.6) n = 3
5.81/7.89
333
«.02,.09,.05) n = 3
«.015,.276,.11) n = 3
(.1,. 2.1, .14) n = 3
4/89
Dry
8.65
2760
<.015 n = 1
..
7.5/7.57
772
2.0 n = 1
(1.6,2.5,2.0)
n = 2
2.0 n=1
6.92/7.44
452
(.02..05..035)
n = 3
«.015,.093.
.036) n = 3
(.02,.12,.07)
n = 2
5/89
Dry
8.06
1811
<.02 n=1
<.02 .n=1
<.02 n=1
7.39
842
2.2 n=1
4.0 n=1
7.62
639
.03 n=1
-
.09 n=1
6/89
Dry
7.77
1290
<.02 n = 1
__
<.02 n=1
7.02
801
2.12 n=1
2.76 n = 1
-
--
-
-
--
7/89
Dry
Dry
7.5
901
3.73 n=1
4.74 n=1
--
-
--
--
-
I
1
-------
Table 5-21. Monthly Average for Selected Sample Results, Rain Facility, 1989 (continued)
Sample
Location
RAIN
BACK-
GROUND
SPRING 1
Parameter
PH
EC
Cyanide
WAD
Cyanide
Free
Cyanide
tot
,1/89
2/89
--
--
..
..
-
3/89
6.75
128
<.02 n = 1
.003 n=1
<.02 n=1
4/89
--
-
-
_.
-
5/89
6/89
7/89
I
a
5
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Site Visit Report: Newmont Gold Company Rain Facility
APPENDIX 5-E
COMMENTS SUBMITTED BY NEWMONT GOLD COMPANY
ON DRAFT SITE VISIT REPORT
' 5-77
-------
Site Visit Report: Newmont Gold Company Rain Facility
[Comments not reproduced for this electronic version. Copies may be
obtained from U.S. EPA, Office of Solid Wastes, Special Waste
Branch.]
5-78
-------
Site Visit Report: Newmont Gold Company Rain Facility
APPENDIX 5-F
EPA RESPONSE TO COMMENTS SUBMITTED BY
NEWMONT GOLD COMPANY
5-79
-------
Site Visit Report: .Newmont Gold Company Rain Facility
EPA Response to Comments Submitted by
Newmont Gold Company on Draft Site Visit Report
EPA has revised the report to address all of the comments made by Newmont Gold Company in a
letter dated May 15, 1992 (see Appendix E). In some cases, EPA made changes to wording
suggested by Newmont, either for brevity, in order to attribute the changes to Newmont, or to
enhance clarity.
It should be noted that Newmont states in its comments that it does not believe that RCRA §3001 or
§3007 provided EPA with the authority to conduct the site visit and document review at the Rain
facility. EPA disagrees. Notwithstanding its position on the authority under which the site visit and
data collection occurred, Newmont cooperated with EPA before, during, and after the site visit.
Newmont's cooperation is appreciated.
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, IL 60604-3590
5-80
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