EXTRACTION.pdf

EPA 530-R-94-035

NTIS PB94-201811

T ECHNICAL R ESOURCE D OCUMENT

EXTRACTION AND BENEFICIATION OF

ORES AND MINERALS

VOLUME 6

GOLD PLACERS

October 1994

U.S. Environmental Protection Agency

Office of Solid Waste

Special Waste Branch

401 M Street, SW

Washington, DC 20460

Technical Resource Document: Gold Placers

DISCLAIMER AND ACKNOWLEDGEMENTS

This document was prepared by the U.S. Environmental Protection Agency

(EPA). The mention of company or product names is not to be considered

an endorsement by the U.S. Government or by EPA.

This Technical Resource Document consists of three sections. The first is

EPA's Profile of the gold placer mining industry; the following sections are

reports on site visits conducted by EPA to gold placer mines in Alaska.

The Profile section was distributed for review to the U.S. Department of the

Interior's Bureau of Mines, the State of Alaska Department of Natural

Resources and Department of Environmental Conservation, the Interstate

Mining Compact Commission, the American Mining Congress, the Mineral

Policy Center, and public interest groups. Summaries of the comments

received on the draft profile and of EPA's responses are presented as an

appendix to this section. The site visit sections were provided to

representatives of the companies and of state agencies who participated in

the site visit. Their comments and EPA's responses are presented as

appendices to the specific site visit section. EPA is grateful to all

individuals who took the time to review sections of this Technical Resource

Document.

The use of the terms "extraction," "beneficiation," and "mineral processing"

in this document is not intended to classify any waste stream for the

purposes of regulatory interpretation or application. Rather, these terms are

used in the context of common industry terminology.

Technical Resource Document: Gold Placers

TABLE OF CONTENTS

Page

1.0 M INING I NDUSTRY P ROFILE : G OLD P LACERS . ........................................... 1-1

1.1 INTRODUCTION ... ......................................................... 1-1

1.2 ECONOMIC CHARACTERIZATION OF THE GOLD PLACER INDUSTRY . ......... 1-2

1.2.1 Background ........................................................ 1-2

1.2.2 Current Operations ................................................... 1-3

1.3 PHYSICAL CHARACTERIZATION OF PLACER DEPOSITS . ...................... 1-6

1.4 GOLD PLACER MINING PRACTICES .. ....................................... 1-10

1.4.1 Background ....................................................... 1-10

1.4.2 Extraction Methods ................................................. 1-11

1.4.2.1 Open Cut Methods ......................................... 1-13

1.4.2.2 Other Methods ............................................. 1-14

1.4.3 Beneficiation Methods ............................................... 1-18

1.4.3.1 Sizing .................................................... 1-19

1.4.3.2 Coarse Concentration ....................................... 1-21

1.4.3.3 Fine Concentration ......................................... 1-22

1.4.3.4 Mercury Amalgamation ..................................... 1-26

1.5 WASTE MANAGEMENT PRACTICES . ....................................... 1-26

1.5.1 Extraction and Beneficiation Wastes and Materials ........................ 1-26

1.5.1.1 Waste Rock or Overburden ................................... 1-27

1.5.1.2 Tailings .................................................. 1-27

1.5.2 Waste and Materials Management ...................................... 1-28

1.5.2.1 Tailings Impoundments/Settling Pond Systems ................... 1-29

1.6 ENVIRONMENTAL EFFECTS . .............................................. 1-38

1.6.1 Surface Water ...................................................... 1-39

1.6.2 Ground Water ...................................................... 1-41

1.6.3 Soil .............................................................. 1-41

1.6.4 Wetlands .......................................................... 1-41

1.6.5 Wildlife ........................................................... 1-41

1.7 MITIGATING MEASURES AND REMEDIATION . .............................. 1-43

1.7.1 Tailings ........................................................... 1-43

1.7.2 Stream Channel .................................................... 1-43

1.7.3 Floodplain ......................................................... 1-44

1.7.4 Soils ............................................................. 1-45

1.7.5 Mined Land Remediation ............................................. 1-46

1.8 CURRENT REGULATORY AND STATUTORY FRAMEWORK .. ................. 1-47

1.8.1 Environmental Protection Agency Regulations ............................ 1-47

1.8.1.1 Resource Conservation and Recovery Act ....................... 1-47

1.8.1.2 Clean Water Act ........................................... 1-48

1.8.1.3 Dredged and Fill Material .................................... 1-49

1.8.2 Department of the Interior ............................................ 1-51

1.8.2.1 Bureau of Land Management ................................. 1-51

1.8.2.2 National Park Service and Fish and Wildlife Service ............... 1-52

1.8.3 Department of Agriculture (Forest Service) .............................. 1-53

1.8.4 State Programs ..................................................... 1-53

1.8.4.1 Alaska ................................................... 1-53

1.8.4.2 Colorado ................................................. 1-56

1. 9 REFERENCES . ............................................................ 1-59

Technical Resource Document: Gold Placers

2. 0 S ITE V ISIT R EPORTS : A LASKA P LACER M INES . ........................................... 2-1

2. 1 INTRODUCTION .. .......................................................... 2-1

2. 2 POLAR MINING, INC . . ...................................................... 2-1

2.2.1 General Facility Description ........................................... 2-1

2.2.2 Regulatory Requirements and Compliance ................................ 2-9

2. 3 ALF HOPEN . .............................................................. 2-11

2.3.1 General Facility Description .......................................... 2-11

2.3.2 Regulatory Requirements and Compliance ............................... 2-13

2.4 COOK'S MINING . .......................................................... 2-14

2.4.1 General Facility Description .......................................... 2-14

2.4.2 Regulatory Requirements and Compliance ............................... 2-16

2.5 REFERENCES .. ........................................................... 2-17

3. 0 S ITE V ISIT R EPORT : V ALDEZ C REEK M INE C AMBIOR A LASKA I NCORPORATED .. ................ 3-1

3.1 INTRODUCTION .. .......................................................... 3-1

3.1.1 Background ........................................................ 3-1

3.1.1.1 General Description ......................................... 3-2

3.1.2 Environmental Setting ................................................ 3-7

3.1.2.1 Geology ................................................... 3-7

3.1.2.2 Surface Water ............................................. 3-10

3.1.2.3 Ground Water ............................................. 3-10

3. 2 FACILITY OPERATION .. ................................................... 3-11

3.2.1 General Overview ................................................... 3-11

3.2.2 Extraction ......................................................... 3-11

3.2.2.1 Excavation ................................................ 3-12

3.2.2.2 Water Management ......................................... 3-14

3.2.3 Beneficiation ...................................................... 3-15

3.2.3.1 Ancillary Facilities ......................................... 3-18

3.3 MATERIALS AND WASTE MANAGEMENT . .................................. 3-18

3.3.1 Waste Rock ....................................................... 3-18

3.3.2 Tailings ........................................................... 3-18

3.3.3 Other Materials .................................................... 3-23

3.4 REGULATORY REQUIREMENTS AND COMPLIANCE . ........................ 3-26

3.4.1 Federal Permits ..................................................... 3-26

3.4.1.1 Bureau of Land Management ................................. 3-26

3.4.1.2 Army Corp of Engineers ..................................... 3-26

3.4.1.3 Environmental Protection Agency ............................. 3-26

3.4.2 State Permits ...................................................... 3-27

3.4.2.1 Dam Safety ............................................... 3-27

3.4.2.2 Diversion Channel .......................................... 3-28

3.4.2.3 Alaska Fish and Game ...................................... 3-28

3.4.2.4 Solid Waste Permit ......................................... 3-28

3.4.3 Inspections and Compliance Incidents ................................... 3-29

3.4.3.1 Inspections ................................................ 3-29

3.4.3.2 Compliance Incidents ....................................... 3-30

3.5 REFERENCES . ............................................................ 3-31

iii

Technical Resource Document: Gold Placers

APPENDICES

APPENDIX 1-A

ACRONYMS . .. ................................................... 1-65

APPENDIX 1-B

COMMENTS SUBMITTED BY U.S. BUREAU OF MINES ON

DRAFT GOLD PLACER PROFILE .. ........................ .......... 1-68

APPENDIX 1-C

RESPONSE TO COMMENTS SUBMITTED BY U.S. BUREAU

OF MINES ON DRAFT GOLD PLACER PROFILE REPORT ... ........... 1-70

APPENDIX 3-A

COMMENTS SUBMITTED BY CAMBIOR ALASKA INC., ON

DRAFT SITE VISIT REPORT .. ............................ ........... 3-33

APPENDIX 3-B

EPA RESPONSE TO COMMENTS SUBMITTED BY

CAMBIOR ALASKA INCORPORATED ON DRAFT SITE

VISIT REPORT . .................................... ................ 3-34

APPENDIX 3-C

COMMENTS SUBMITTED BY THE STATE OF ALASKA ON

DRAFT SITE VISIT REPORT ............................. ............ 3-36

APPENDIX 3-D

EPA RESPONSE TO COMMENTS SUBMITTED BY THE

STATE OF ALASKA ON DRAFT SITE VISIT REPORT ... ............... 3-37

LIST OF TABLES

Page

Table 1-1.

EPA and Bureau of Mines Estimates of Operational Placer Mines . ................... 1-5

Table 1-2.

Turbidity and Arsenic Levels in Two Alaskan Creeks . ............................ 1-40

Table 3-1.

Estimated Volumes of Overburden and Pay-Gravel . ............................. 3-13

Table 3-2.

Theoretical Efficiency of Settling Ponds . ...................................... 3-20

Table 3-3.

NPDES Discharge Rates .. .................................................. 3-22

Table 3-4.

Storage Tank Summary . .................................................... 3-25

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