Twin Creeks Mine : final environmental impact statement, v. 1

490 Pages·1996·116.1 MB·English

by  United States. Bureau of Land Management. Winnemucca District

BLM LIBRARY
United States Department of the Interior
88047029
Bureau of Land Management
^V-^P
Winnemucca District Office
Winnemucca, Nevada December 1996
Final
Environmental Impact Statement
Twin Creeks Mine
Volume
I
Existing Twin Creeks Mine
MISSION STATEMENT
The Bureau of Land Managementis responsibleforthe stewardship of our public lands. It is committed to
manage, protect, and improve these lands in a manner to serve the needs of the American people for all
times. Management is based upon the principles of multiple use and sustained yield of our nation's
resources within a framework of environmental responsibility and scientific technology. These resources
include recreation, rangelands, timber, minerals, watershed, fish and wildlife, wilderness, air and scenic,
scientificand cultural values.
BLM/WN/PL-96/004+1610
United States Department of the Interior
BUREAU OF LAND MANAGEMENT T4STt
Winnemucca District Office
5100 East Winnemucca Boulevard
Y.I
Winnemucca, Nevada 89445
702-623-1500
In Reply Refer To:
1793/3809
(NV-020)
December 12, 1996
Dear Reader:
Enclosed is the Final Environmental Impact Statement (EIS) for Santa Fe Pacific Gold
Corporation's Twin Creeks Mine, prepared by the Bureau of Land Management (BLM),
Winnemucca District Office.
This Final Environmental Impact Statement analyzes the direct, indirect and cumulative impacts
associated with continued mining and expansion of the South pit, ore processing facilities,
overburden and interburden storage areas, expanded dewatering system and water disposal
facilities, diversion of Rabbit Creek and tributaries, and ancillary facilities.
This Final Environmental Impact Statement (EIS) contains in its entirety the analysis originally
presented in the Draft EIS (issued July 5, 1996), with all text changes highlighted. In addition,
the Final EIS also includes an evaluation of two additional alternatives, the West Side alternative
(overburden/interburden reconfiguration) and the East Side alternative (stormwater control), that
were not analyzed in the Draft EIS. Also included in the Final EIS are responses to comments
received during the public comment period on the Draft EIS. The document also incorporates
mitigation to minimize impacts to each resource. The FEIS and the DEIS constitute the complete
EIS.
Following a 30 day availability period of this FEIS, a Record of Decision will be issued. You
may direct comments or questions to Gerald Moritz, Project Manager, at the Bureau of Land
Management, Winnemucca District Office, 5100 East Winnemucca Boulevard, Winnemucca,
Nevada 89445.
Sincerely yours,
Ron Wenker
is, °o
District Manager
°o**> *»^
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FINAL
ENVIRONMENTAL IMPACT STATEMENT
TWIN CREEKS MINE
Lead Agency: U.S. Department of the Interior
Bureau of Land Management
Winnemucca District Office
Project Location: Humboldt County, Nevada
Correspondence on this Final EIS Gerald Moritz, EIS Project Manager
Should be Directed to: Bureau of Land Management
Winnemucca District Office
5100 East Winnemucca Boulevard
Winnemucca, Nevada 89445
[phone]
Date Draft EIS Filed with EPA: July 5. 1996
Date Final EIS Filed with EPA: X 1996
This environmental impact statement (EIS^ analyzes the impacts that would occur with the implementation of
Santa Fe Pacific Gold Corporation's (SFPGls) Revised Final BLM Plan of Operations and NDEP Reclamation
Plan and Permit Application for the Twin Creeks Mine, which encompasses the former Rabbit Creek and
Chimney Creek mines. The proposed project would include South Pit expansion; overburden and interburden
storage areas; additional milling, flotation, and tailings facilities; additional heap leaching and processing
facilities; expanded dewatering system and water disposal facilities; diversion of Rabbit Creek and tributaries;
utility corridors; ancillary facilities; and Humboldt County road relocation. The proposed expansion would affect
4,866 acres of public land administered by the BLM. All of this acreage occurs within the existing SFPG permit
boundary. Construction is scheduled to begin upon approval, which is anticipated to be in early 1997. and be
completed in early 1998; operation of the expanded facilities would begin thereafter and continue through the
year 2011.
Ih^Draft EIS analyzed the environmental impacts associated with the proposed mine consolidation and
expansion (Proposed Action), the No Action alternative, the Partial Vista Pit Backfill alternative, the Selective
Handling of Overburden and Interburden alternative, and the Overburden and Interburden Storage Area
alternatives. This Final EIS ncludes an evaluation of two additional alternatives, the West Side alternative
i
foverburden/interburden reconfiguration) and the East Side alternative (stormwater control) that were not
,
analyzed in the Draft EIS. This Final EIS also includes responses to comments received by the Bureau of
Land Management (BLM^ to the Draft EIS during the public comment period.
Responsible Official for EIS:
Ron Wenker
Winnemucca District Manager
Twin Creeks Mine Final EIS

1
Table of Contents
TABLE OF CONTENTS
Page
Cover Sheet
Summary
ix
1.0 INTRODUCTION 1-1
1.1 Purpose of and Need forthe Proposed Action 1-1
1.2 Relationship to BLM and Non-BLM Policies, Plans, and Programs 1-1
1.3 Authorizing Actions 1-3
1.4 Organization of the Environmental Impact Statement 1-4
2.0 DESCRIPTION OF THE PROPOSED ACTION AND THE ALTERNATIVES 2-1
2.1 Introduction 2-1
2.2 Existing Facilities and Operations 2-1
2.2.1 Former Chimney Creek Mine 2-1
2.2.2 Former Rabbit Creek Mine 2-9
2.3 No Action Alternative 2-10
2.3.1 Exploration, Development, and Condemnation Drilling 2-11
2.3.2 Open Pit Expansion 2-11
2.3.3 Development and Expansion of Overburden and Interburden Storage Areas 2-11
2.3.4 Sulfide Ore Stockpiles 2-16
2.3.5 Construction of Phase 1 of the Sulfide (Sage) Mill 2-17
2.3.6 Development and Expansion of Tailings Storage Areas 2-17
2.3.7 Development of an Additional Heap Leaching Facility 2-18
2.3.8 Development of Limestone Storage Area 2-19
2.3.9 Development of Dewatering Wells, Water Distribution Pond, and Water
Treatment Plant 2-19
2.3.10 Development of Reinfiltration Basins 2-19
2.3.1 New Haul and Access Roads 2-20
2.3.12 Construction of Ancillary Facilities 2-20
2.3.13 Development of a Bioremediation Site 2-20
2.3.14 Employment 2-20
2.3.15 Land Ownership 2-20
2.4 Proposed Action 2-22
2.4.1 Consolidation of Former Rabbit Creek Mine and Former Chimney Creek Mine....2-22
2.4.2 South Pit Expansion 2-22
2.4.3 Overburden and Interburden Storage Areas 2-27
2.4.4 Additional Milling, Flotation Circuit, and Tailings Facilities 2-29
2.4.5 Additional Heap Leaching and Processing Facilities 2-32
2.4.6 Dewatering System and Water Disposal Facilities 2-33
2.4.7 Surface Water Control Features 2-34
2.4.8 Ancillary Facilities 2-35
2.4.9 Relocation of Humboldt County Road 2-36
2.4.10 Employment 2-36
2.4.11 Reclamation 2-37
2.4.12 Land Ownership 2-51
2.5 Other Project Alternatives 2-51
2.5.1 Alternatives Considered in Detail 2-52
2 5.2 Alternatives Considered but Eliminated From Detailed Analysis 2-56
2.6 Past, Present, and Reasonably Foreseeable Future Actions 2-62
2.6.1 Past and Present Actions 2-66
2.6.2 Reasonably Foreseeable Future Actions 2-69
Twin Creeks Mine Final EIS
TABLE OF CONTENTS
TABLE OF CONTENTS (Continued)
Page
2.7 Agency Preferred Alternative 2-71
2.8 Comparative Analysis of Alternatives 2-71
3.0 AFFECTED ENVIRONMENT AND ENVIRONMENTAL CONSEQUENCES 3-1
3.1 Geology and Minerals 3-3
3.1.1 Affected Environment 3-3
3.1.2 Environmental Consequences 3-18
3.1.3 Cumulative Impacts 3-28
3.1.4 Monitoring and Mitigation Measures 3-28
3.1.5 Residual Adverse Effects 3-31
3.2 Water Resources 3-33
3.2.1 Affected Environment 3-33
3.2.2 Environmental Consequences 3-59
3.2.3 Cumulative Impacts 3-111
3.2.4 Monitoring and Mitigation Measures 3-116
3.2.5 Residual Adverse Effects 3-120
3.3 Soils 3-121
3.3.1 Affected Environment 3-121
3.3.2 Environmental Consequences 3-130
3.3.3 Cumulative Impacts 3-133
3.3.4 Monitoring and Mitigation Measures 3-133
3.3.5 Residual Adverse Effects 3-134
3.4 Vegetation 3-135
3.4.1 Affected Environment 3-135
3.4.2 Environmental Consequences 3-145
3.4.3 Cumulative Impacts 3-153
3.4.4 Monitoring and Mitigation Measures 3-153
3.4.5 Residual Adverse Effects 3-154
3.5 Wildlife and Fisheries Resources 3-155
3.5.1 Affected Environment 3-155
3.5.2 Environmental Consequences 3-170
3.5.3 Cumulative Impacts 3-187
3.5.4 Monitoring and Mitigation Measures 3-189
3.5.5 Residual Adverse Effects 3-192
3.6 Range Resources 3-193
3.6.1 Affected Environment 3-193
3.6.2 Environmental Consequences 3-199
3.6.3 Cumulative Impacts 3-206
3.6.4 Monitoring and Mitigation Measures 3-206
3.6.5 Residual Adverse Effects 3-207
3.7 Paleontological Resources 3-209
3.7.1 Affected Environment 3-209
3.7.2 Environmental Consequences 3-209
3.7.3 Cumulative Impacts 3-209
3.7.4 Monitoring and Mitigation Measures 3-210
3.7.5 Residual Adverse Effects 3-210
3.8 Cultural Resources 3-211
3.8.1 Affected Environment 3-211
3.8.2 Environmental Consequences 3-218
3.8.3 Cumulative Impacts 3-219
ii Twin Creeks Mine Final EIS
Table of Contents
TABLE OF CONTENTS (Continued)
Page
3.8.4 Monitoring and Mitigation Measures 3-220
3.8.5 Residual Adverse Effects 3-222
3.9 AirQuality 3-223
3.9.1 Affected Environment 3-223
3.9.2 Environmental Consequences 3-226
3.9.3 Cumulative Impacts 3-230
3.9.4 Monitoring and Mitigation Measures 3-230
3.9.5 Residual Adverse Effects 3-231
3.10 Land Use and Access 3-233
3.10.1 Affected Environment 3-233
3.10.2 Environmental Consequences 3-234
3.10.3 Cumulative Impacts 3-240
3.10.4 Monitoring and Mitigation Measures 3-240
3.10.5 Residual Adverse Effects 3-241
3.11 Recreation and Wilderness 3-243
3.11.1 Affected Environment 3-243
3.11.2 Environmental Consequences 3-244
3.11.3 Cumulative Impacts 3-245
3.11.4 Monitoring and Mitigation Measures 3-246
3.11.5 Residual Adverse Effects 3-246
3.12 Social and Economic Values 3-247
3.12.1 Affected Environment 3-247
3.12.2 Environmental Consequences 3-256
3.12.3 Cumulative Impacts 3-269
3.12.4 Monitoring and Mitigation Measures 3-270
3.12.5 Residual Adverse Effects 3-270
3.13 Visual Resources 3-271
3.13.1 Affected Environment 3-271
3.13.2 Environmental Consequences 3-272
3.13.3 Cumulative Impacts 3-274
3.13.4 Monitoring and Mitigation Measures 3-274
3.13.5 Residual Adverse Effects 3-275
3.14 Noise 3-277
3.14.1 Affected Environment 3-277
3.14.2 Environmental Consequences 3-277
3.14.3 Cumulative Impacts 3-279
3.14.4 Monitoring and Mitigation Measures 3-279
3.14.5 Residual Adverse Effects 3-279
3.15 Hazardous Materials 3-281
3.15.1 Affected Environment 3-281
3.15.2 Environmental Consequences 3-281
3.15.3 Cumulative Impacts 3-292
3.15.4 Monitoring and Mitigation Measures 3-293
3.15.5 Residual Adverse Effects 3-293
3.16 Relationships Between Short-Term Uses of the Environment and the Maintenance
and Enhancement of Long-Term Productivity 3-295
3.17 Irreversible and Irretrievable Commitment of Resources 3-297
3.17.1 Geology and Minerals 3-297
3.17.2 Water Quantity and Quality 3-297
3.17.3 Soils 3-297
Twin Creeks Mine Final EIS Mi
1
TABLE OF CONTENTS
TABLE OF CONTENTS (Continued)
Page
3.17.4 Vegetation 3-297
3.17.5 Wildlife and Fisheries Resources 3-297
3.17.6 Range Resources 3-298
3.17.7 Paleontological Resources 3-298
3.17.8 Cultural Resources 3-298
3.17.9 Air Quality 3-298
3.17.10 Land Use and Access 3-298
3.17.1 Recreation and Wilderness 3-298
3.17.12 Social And Economic Values 3-298
3.17.13 Visual Resources 3-298
3.17.14 Noise 3-298
3.17.15 Hazardous Materials 3-298
4.0 CONSULTATION AND COORDINATION 4-1
4.1 Public Participation and Scoping 4-1
4.2 List of Agency Contacts 4-1
4.2.1 Federal Agencies 4-1
4.2.2 State Agencies/Universities 4-1
4.2.3 Local Agencies 4-1
4.2.4 Private Organizations and Companies 4-2
4.3 List of Agencies, Organizations, and Persons to Whom Copies of This
Statement are Sent 4-2
4.4 Public Review 4-6
4.4.1 Written Comments and Responses 4-6
4.4.2 Public Meeting Comments and Responses 4-7
5.0 LIST OF PREPARERS AND REVIEWERS 5-1
5.1 Bureau of Land Management EIS Team 5-1
5.2 Riverside Technology, inc. EIS Team 5-1
6.0 REFERENCES 6-1
GLOSSARY
7.0 7-1
8.0 INDEX 8-1
APPENDIX A - Summary of Water Quality Data A-1
APPENDIX B - Wildlife Species Lists B-1
APPENDIX C - Ecological Risk Assessment C-1
APPENDIX D - Human Health Risk Assessment D-1
APPENDIX E - National Register of Historic Places Status of Cultural Resources Within the
Project Area E-1
APPENDIX F - Public Comments and Responses to the Draft EIS F-1
iv Twin Creeks Mine Final EIS