Arizona mining BADCT guidance manual : aquifer protection program

              ARIZONA MINING
GUIDANCE MANUAL
BADCT
Publication # TB 04-01
ARIZONA DEPARTMENT OF ENVIRONMENTAL QUALITY
1110 West Washington Street
Phoenix, Arizona 85007
(602) 771-2300 or 1-800-234-5677 in Arizona
TDD Number (602) 771-4829
ARIZONA MINING BADCT
GUIDANCE MANUAL
Aquifer Protection Program
ACKNOWLEDGMENTS
The publication of Arizona’s new mining BADCT (Best Available Demonstrated Control
Technology) document represents a milestone in protecting groundwater under the state's
Aquifer Protection Permit (APP) program. Its successful completion combined the efforts of
ADEQ staff and members of the mining community in an unprecedented cooperative venture to
develop guidance for protecting groundwater for future uses. ADEQ is greatly indebted to the
“Small BADCT Committee” for the thousands of hours its members invested in the preceding 18
months to produce this guidance manual. Without their patience, cooperation and perseverance,
this project could not have been completed.
SMALL BADCT COMMITTEE
ADEQ PARTICIPANTS MINING INDUSTRY PARTICIPANTS
Dennis L. Turner, Chairman George H. Beckwith, P.E.
Michael D. Greenslade, P.E. Derek J. Cooke
James F. Dubois Colleen D. Kelley
Michael J. Wood Robin A. Kettlewell
Richard N. Mohr
Dirk Van Zyl, P.E., Ph.D.
This document also greatly benefited from an independent technical review performed by TRC
Environmental Solutions, Inc., lead by Dr. Ian Hutchison. Dr. Hutchison, along with Dr. Richard
D. Ellison, edited “Mine Waste Management,” a publication sponsored by the California Mining
Association. Drs. Hutchison and Ellison are internationally recognized water quality
management experts and designers of mine waste management units, as well as authorities in
developing mine waste regulations appropriate to those issues. The technical editorial team
consisted of:
Ian P. G. Hutchison, Ph.D., P.E.
Joseph L. Stenger, R.G.
Michael L. Leonard Sr., P.E.
Deanna Stamboulian
Joe Gelt of the University of Arizona’s Water Resources Research Center edited and formatted
the final copy; Ken Seasholes of WRRC designed the cover. Deborah L. Patton of ADEQ was
responsible for the final edit and press preparation.
i
USE OF MANUAL
At a minimum, readers are encouraged to read the following sections:
• Introduction
• Part 1 - General BADCT Information
Thereafter, if they intend to submit a Prescriptive BADCT design they should review:
• Part 2 - Prescriptive BADCT Criteria
• Section 2.1 - Introduction
• The sections that apply to their facilities selected from 2.2 to 2.5
If they intend to submit an Individual BADCT design they should review:
• Part 3 - Individual BADCT Guidance
• Section 3.1 - Introduction
• The sections that apply to their facilities selected from 3.2 to 3.6.
The Appendices are available for further detailed review. The more important are:
• Appendix B: Solution Ore and Waste Characterization
• Appendix C: Liner Design, Principals and Practice
• Appendix E: Engineering Design Guidance
ii
TABLE OF CONTENTS
PAGE NO.
INTRODUCTION
Purpose and Scope ........................................................................................................1
BADCT Selection Process Overview...............................................................................2
How to Use This Manual..................................................................................................3
Facilities Requiring BADCT ............................................................................................5
PART 1 - GENERAL BADCT INFORMATION.................................................................1-1
1.1 The BADCT Process...............................................................................................1-1
1.1.1 Prescriptive BADCT...................................................................................1-3
1.1.2 Prescriptive BADCT Review Process ........................................................1-3
1.1.2.1 Determination of Prescriptive BADCT .......................................1-6
1.1.3 Individual BADCT Review Process For New Facilities ............................1-6
1.1.3.1 Site Selection ...............................................................................1-8
1.1.3.2 Development of Reference Design .............................................1-11
1.1.3.3 Estimation of Aquifer Loading ...................................................1-11
1.1.3.4 Alternative Design(s) Selection ..................................................1-17
1.1.3.5 Estimation of Aquifer Loading for Alternative Design(s)..........1-17
1.1.3.6 Selection of BADCT Design ......................................................1-17
1.1.3.7 Economic Considerations ...........................................................1-18
1.1.3.8 Discussion...................................................................................1-19
1.1.4 Individual BADCT Review Process for Existing Facilities ......................1-19
1.1.4.1 Steps 1 & 2: Identifying Current Discharge Controls
and Assessing Their Performance - The Reference Design........1-20
1.1.4.2 Step 3: Identifying Technically Feasible DCTs
for Improvement .........................................................................1-21
1.1.4.3 Step 4: Use Candidate List to Arrive at One or More
Alternative Discharge Control Systems......................................1-22
1.1.4.4 Step 5: Weigh Cost vs. Discharge Reduction by
Calculating Aquifer Loading for Alternative System(s)
and Calculating Cost for New DCTs ..........................................1-22
1.2 Using Site Characteristics as a part of the BADCT Design...................................1-22
1.2.1 Waste Types and Process Solution Characteristics ...................................1-22
1.2.2 Water Resource Values..............................................................................1-25
1.2.3 Climatic Conditions ...................................................................................1-26
1.2.4 Site Factors.................................................................................................1-28
1.2.4.1 Topography.................................................................................1-29
1.2.4.2 Geology/Stability ........................................................................1-30
1.2.4.3 Soil Properties.............................................................................1-31
1.2.4.4 Surface Hydrology......................................................................1-31
1.2.4.5 Hydrogeology .............................................................................1-32
1.2.4.6 Barriers........................................................................................1-35
1.2.5 Passive Containment..................................................................................1-35
1.3 Using Liners as a Part of the BADCT Design .......................................................1-36
PART 2 - PRESCRIPTIVE BADCT CRITERIA .................................................................2-1
2.1 Introduction.............................................................................................................2-1
TABLE OF CONTENTS
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2.2 Non-Storm Water Ponds.........................................................................................2-5
2.2.1 Siting Criteria..............................................................................................2-5
2.2.1.1 Site Characterization....................................................................2-5
2.2.1.2 Surface Water Control .................................................................2-6
2.2.1.3 Geologic Hazards.........................................................................2-6
2.2.2 Design, Construction and Operations Criteria............................................2-7
2.2.2.1 Solution/Effluent Characterization ..............................................2-7
2.2.2.2 Capacity and Storage Design .......................................................2-7
2.2.2.3 Site Preparation............................................................................2-7
2.2.2.4 Liner Specifications .....................................................................2-7
2.2.2.5 Stability Design............................................................................2-8
2.2.3 Facility Inspection Criteria .........................................................................2-9
2.2.4 Closure/Post-Closure Criteria ....................................................................2-11
2.3 Process Solution Ponds..........................................................................................2-17
2.3.1 Siting Criteria.............................................................................................2-17
2.3.1.1 Site Characterization...................................................................2-17
2.3.1.2 Surface Water Control ................................................................2-18
2.3.1.3 Geologic Hazards........................................................................2-18
2.3.2 Design, Construction and Operations Criteria...........................................2-19
2.3.2.1 Solution/Effluent Characterization .............................................2-19
2.3.2.2 Capacity and Storage Design ......................................................2-19
2.3.2.3 Site Preparation...........................................................................2-19
2.3.2.4 Liner Specifications ....................................................................2-19
2.3.2.5 Leak Collection and Removal System (LCRS) ..........................2-21
2.3.2.6 Stability Design...........................................................................2-21
2.3.3 Facility Inspection Criteria ........................................................................2-23
2.3.4 Closure/Post-Closure Criteria ....................................................................2-23
2.4 Heap Leach Pads....................................................................................................2-31
2.4.1 Siting Criteria.............................................................................................2-31
2.4.1.1 Site Characterization...................................................................2-31
2.4.1.2 Surface Water Control ................................................................2-32
2.4.1.3 Geologic Hazards........................................................................2-32
2.4.2 Design, Construction and Operations Criteria...........................................2-32
2.4.2.1 Solution and Waste Characterization..........................................2-33
2.4.2.2 Site Preparation...........................................................................2-33
2.4.2.3 Liner Specifications ....................................................................2-33
2.4.2.4 Perimeter Containment ...............................................................2-35
2.4.2.5 Stability Design...........................................................................2-35
2.4.3 Facility Inspection Criteria ........................................................................2-36
2.4.4 Closure/Post-Closure Criteria ....................................................................2-38
2.5 Tailing Impoundments ...........................................................................................2-43
2.5.1 Siting Criteria.............................................................................................2-43
2.5.1.1 Site Characterization...................................................................2-43
2.5.1.2 Surface Water Control ................................................................2-44
2.5.1.3 Geologic Hazards........................................................................2-44
2.5.2 Design, Construction and Operations Criteria...........................................2-45
TABLE OF CONTENTS
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2.5.2.1 Solution and Tailing Characterization ........................................2-45
2.5.2.2 Capacity and Storage Design ......................................................2-45
2.5.2.3 Site Preparation...........................................................................2-45
2.5.2.4 Liner Specifications ....................................................................2-45
2.5.2.5 Stability Design...........................................................................2-47
2.5.3 Facility Inspection Criteria ........................................................................2-49
2.5.4 Closure/Post-Closure Criteria ....................................................................2-49
PART 3 - INDIVIDUAL BADCT GUIDANCE...................................................................3-1
3.1 Introduction.............................................................................................................3-1
3.2 Heap Leach Pads.....................................................................................................3-2
3.2.1 Introduction.................................................................................................3-2
3.2.2 Solution and Waste Characterization..........................................................3-2
3.2.3 Siting Considerations..................................................................................3-3
3.2.3.1 Climate and Surface Hydrology...................................................3-4
3.2.3.2 Subsurface Conditions .................................................................3-4
3.2.3.3 Geologic Hazards.........................................................................3-4
3.2.3.3.1 Landslides ..................................................................3-5
3.2.3.3.2 Subsidence and Settlement ........................................3-5
3.2.3.3.3 Earthquake-Induced Ground Failure..........................3-6
3.2.3.3.4 Collapsing Soils .........................................................3-7
3.2.4 Design, Construction and Operations Considerations ................................3-7
3.2.4.1 Site Preparation............................................................................3-7
3.2.4.2 Surface Water Control .................................................................3-8
3.2.4.3 Discharge Control ........................................................................3-8
3.2.4.3.1 Natural Containment and Liners................................3-9
3.2.4.3.2 Leachate Collection/Hydrostatic Head Control ........3-10
3.2.4.3.3 Solution Control and Storage....................................3-11
3.2.4.4 Stability Design...........................................................................3-11
3.2.4.5 Operational Measures .................................................................3-12
3.2.4.6 Operational Monitoring ..............................................................3-13
3.2.5 Closure/Post-Closure .................................................................................3-14
3.2.5.1 Physical Stability ........................................................................3-15
3.2.5.2 Chemical Stability.......................................................................3-16
3.2.5.2.1 General......................................................................3-16
3.2.5.2.2 Rinsing/Detoxification..............................................3-17
3.3 Dump Leaching Facilities ......................................................................................3-18
3.3.1 Introduction................................................................................................3-18
3.3.2 Solution and Spent Ore Characterization...................................................3-19
3.3.3 Siting Considerations.................................................................................3-19
3.3.3.1 Climate and Surface Hydrology..................................................3-20
3.3.3.2 Subsurface Conditions ................................................................3-21
3.3.3.3 Geologic Hazards........................................................................3-21
3.3.3.3.1 Landslides .................................................................3-21
3.3.3.3.2 Subsidence and Settlement .......................................3-22
3.3.3.3.3 Earthquake-Induced Ground Failure.........................3-22
TABLE OF CONTENTS
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3.3.3.3.4 Collapsing Soils ........................................................3-23
3.3.4 Design Construction and Operations Considerations ................................3-24
3.3.4.1 Site Preparation...........................................................................3-24
3.3.4.2 Surface Water Control ................................................................3-26
3.3.4.3 Discharge Control .......................................................................3-26
3.3.4.4 Stability Design...........................................................................3-28
3.3.4.5 Operational Measures .................................................................3-29
3.3.4.6 Operational Monitoring ..............................................................3-30
3.3.5 Closure/Post-Closure .................................................................................3-31
3.3.5.1 Physical Stability ........................................................................3-31
3.3.5.2 Chemical Stability.......................................................................3-32
3.3.5.2.1 General......................................................................3-32
3.3.5.2.2 Rinsing/Detoxification..............................................3-33
3.4 In-Situ Leaching.....................................................................................................3-34
3.4.1 Introduction................................................................................................3-34
3.4.2 Types of In-Situ Leaching Operations.......................................................3-35
3.4.2.1 In-Situ Leaching With Deep Well Injection ...............................3-35
3.4.2.2 In-Situ Leaching Using the Water Table for Capture.................3-35
3.4.2.3 In-Situ Leaching With Capture Above The Water Table ...........3-36
3.4.3 Solution Characterization...........................................................................3-40
3.4.4 Siting Considerations.................................................................................3-40
3.4.4.1 Climate and Surface Hydrology..................................................3-41
3.4.4.2 Subsurface Conditions ................................................................3-41
3.4.4.3 Geologic Hazards........................................................................3-41
3.4.4.3.1 Landslides .................................................................3-42
3.4.4.3.2 Subsidence and Settlement .......................................3-42
3.4.4.3.3 Earthquake-Induced Ground Failure.........................3-43
3.4.4.3.4 Collapsing Soils ........................................................3-44
3.4.5 Design, Construction and Operations Considerations ...............................3-44
3.4.5.1 Site Preparation...........................................................................3-44
3.4.5.2 Surface Water Control ................................................................3-45
3.4.5.3 Discharge Control .......................................................................3-45
3.4.5.3.1 Discharge Control - In-Situ Leaching
With Deep Well Injection .........................................3-46
3.4.5.3.1.1 Injection Well Mechanical
Integrity - Design .................................3-46
3.4.5.3.1.2 Injection Well Construction.................3-47
3.4.5.3.1.3 Injection Well Operation......................3-47
3.4.5.3.2 Discharge Control - In-Situ Leaching Using
the Water Table for Capture .....................................3-48
3.4.5.3.3 Discharge Control - In-Situ Leaching
With Capture Above The Water Table .....................3-48
3.4.5.4 Stability Design...........................................................................3-49
3.4.5.5 Operational Measures .................................................................3-49
3.4.6 Closure/Post-Closure .................................................................................3-50
3.5 Tailing Impoundments ...........................................................................................3-50
TABLE OF CONTENTS
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3.5.1 Introduction................................................................................................3-50
3.5.2 Solution and Tailing Characterization .......................................................3-52
3.5.3 Siting Considerations.................................................................................3-52
3.5.3.1 Climate and Surface Hydrology..................................................3-53
3.5.3.2 Subsurface Conditions ................................................................3-53
3.5.3.3 Geologic Hazards........................................................................3-54
3.5.3.3.1 Landslides .................................................................3-54
3.5.3.3.2 Subsidence and Settlement .......................................3-54
3.5.3.3.3 Earthquake-Induced Ground Failure.........................3-55
3.5.3.3.4 Collapsing Soils ........................................................3-56
3.5.4 Design, Construction and Operations Considerations ...............................3-56
3.5.4.1 Site Preparation...........................................................................3-57
3.5.4.2 Surface Water Control ................................................................3-57
3.5.4.3 Discharge Control .......................................................................3-58
3.5.4.3.1 Base Metal Tailing Impoundments...........................3-58
3.5.4.3.2 Precious Metals Tailing Impoundments ...................3-59
3.5.4.3.3 Uranium Tailing Impoundments...............................3-60
3.5.4.4 Stability Design...........................................................................3-61
3.5.4.5 Operational Measures .................................................................3-66
3.5.4.6 Operational Monitoring ..............................................................3-66
3.5.5 Closure/Post-Closure .................................................................................3-67
3.6 Surface Ponds.........................................................................................................3-68
3.6.1 Introduction................................................................................................3-68
3.6.2 Solution Characterization...........................................................................3-68
3.6.3 Siting Considerations.................................................................................3-69
3.6.3.1 Climate and Surface Hydrology..................................................3-69
3.6.3.2 Subsurface Conditions ................................................................3-70
3.6.3.3 Geologic Hazards........................................................................3-70
3.6.3.3.1 Landslides .................................................................3-70
3.6.3.3.2 Subsidence and Settlement .......................................3-71
3.6.3.3.3 Earthquake-Induced Ground Failure.........................3-72
3.6.3.3.4 Collapsing Soils ........................................................3-72
3.6.4 Design, Construction and Operations Considerations ...............................3-73
3.6.4.1 Site Preparation...........................................................................3-73
3.6.4.2 Surface Water Control ................................................................3-74
3.6.4.3 Discharge Control .......................................................................3-74
3.6.4.3.1 Liners ........................................................................3-74
3.6.4.3.2 Leak Collection and Removal System (LCRS) ........3-75
3.6.4.4 Stability Design...........................................................................3-76
3.6.4.5 Operational Measures .................................................................3-77
3.6.4.6 Operational Monitoring ..............................................................3-77
3.6.5 Closure/Post-closure ..................................................................................3-77
3.6.5.1 Closure by Removal....................................................................3-78
3.6.5.2 Closure In-Place..........................................................................3-78
TABLE OF CONTENTS
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PART 4 - APPENDICES
A COMPARISON OF COPPER LEACHING FACILITIES
B SOLUTION, ORE AND WASTE CHARACTERIZATION
C LINER DESIGN PRINCIPLES AND PRACTICE
D CONSTRUCTION QUALITY ASSURANCE AND QUALITY CONTROL
E ENGINEERING DESIGN GUIDANCE
F FEDERAL, STATE AND LOCAL ENVIRONMENTAL PERMITS
PART 5 - GLOSSARY OF TECHNICAL TERMS
PART 6 - REFERENCES
INDEX
TABLE OF CONTENTS
(Continued)
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LIST OF TABLES
TABLE NO. TITLE
1-1 Example Table of Contents - Prescriptive BADCT Demonstration.......................1-5
1-2 Example Table of Contents - Individual BADCT Demonstration..........................1-9
1-3 Examples of Demonstrated Control Technologies ................................................1-13
2-1 Examples of Engineering Equivalents ....................................................................2-2
2-2 Non-Storm Water Ponds Prescriptive BADCT .....................................................2-12
2-3 Process Solution Ponds Prescriptive BADCT .......................................................2-25
2-4 Heap Leach Pads Prescriptive BADCT .................................................................2-39
2-5 Tailing Impoundments Prescriptive BADCT ........................................................2-50
LIST OF FIGURES
FIGURE NO. TITLE PAGE NO.
1-1 Example of Prescriptive and Individual BADCT “Zones” ....................................1-2
1-2 Schematic of BADCT Selection Process
For New Facilities ..................................................................................................1-7
2-1 Example of Non-Storm Water Pond Cross-Section...............................................2-10
2-2 Example of Process Solution Pond Cross-Section.................................................2-22
2-3 Example of Heap Leach Pad Cross-Section ..........................................................2-37
2-4 Example of Tailing Impoundment Cross-Section..................................................2-48
3-1 Example of Dump Leach Facility Cross-Section...................................................3-25
3-2 Example of In-Situ Leaching With Deep Well Injection.......................................3-37
3-3 Example of In-Situ Leaching Using the Water Table for Capture ........................3-38
3-4 Example of In-Situ Leaching With Capture Above the Water Table....................3-39
3-5 Tailing Dam Construction Method .......................................................................3-63
3-6 Upstream Tailing Dam Construction Using Cyclones ..........................................3-64
INTRODUCTION
________________________________________________ INTRODUCTION (1)
INTRODUCTION
Purpose and Scope
This guidance manual describes the process that an Aquifer Protection Permit (APP) applicant
should follow in selecting the Best Available Demonstrated Control Technology (BADCT) for a
specific mining facility(1) and site(1) in accordance with Arizona Revised Statute (A.R.S)
49-243.B.1.
This statute requires all permitted facilities to utilize BADCT in their design, construction and
operation while considering various factors depending on whether the facility is new or existing.
The requirements of BADCT are met, according to A.R.S. 49-243.B.1, if it is demonstrated:
AThat the facility will be so designed, constructed and operated as to ensure the greatest
degree of discharge reduction achievable through application of the best available
demonstrated control technology, processes, operating methods or other alternatives,
including, where practicable, a technology permitting no discharge of pollutants. In
determining best available demonstrated control technology, processes, operating
methods or other alternatives the director shall take into account site specific hydrologic
and geologic characteristics and other environmental factors, the opportunity for water
conservation or augmentation and economic impacts of the use of alternative
technologies, processes or operating methods on an industry-wide basis. However, a
discharge reduction to an aquifer achievable solely by means of site specific
characteristics does not, in itself, constitute compliance with this paragraph. In addition,
the director shall consider the following factors for existing facilities:
(a) Toxicity, concentrations and quantities of discharge likely to reach an aquifer from
various types of control technologies.
(b) The total costs of the application of the technology in relation to the discharge
reduction to be achieved from such application.
(c) The age of equipment and facilities involved.
(d) The industrial and control process employed.
(e) The engineering aspects of the application of various types of control techniques.
(f) Process changes.
(g) Non-water quality environmental impacts.
(h) The extent to which water available for beneficial uses will be conserved by a
particular type of control technology.@
Arizona Administrative Code (A.A.C.) R18-9-A202(A)(5) requires that an application for an
APP include a description of the BADCT to be employed at the facility. The procedures and
information presented in this guidance manual are intended for use in determining the
appropriate BADCT, and to assist the applicant=s development and the Arizona Department of
Environmental Quality's (ADEQ=s) review of permit applications.
(2) INTRODUCTION____________________________________
Demonstrating that a facility will be designed, constructed, and operated in accordance with
BADCT requirements is one of five demonstrations required for obtaining an APP permit. Other
required demonstrations include:
$ The facility will not cause or contribute to an exceedance of Aquifer Water Quality
Standards (AWQS) at the point of compliance or, if AWQS for a pollutant has been
exceeded in an aquifer, that no additional degradation will occur (A.A.C. R18-9-
A202(A)(8)(a and b));
$ The person applying for the APP is technically capable of carrying out the conditions
of the permit (A.A.C. R18-9-A202(B));
$ The person applying for the APP is financially capable of constructing, operating,
closing, and assuring proper post-closure care of the facility (A.A.C. R18-9-A203);
and
$ The facility complies with applicable municipal or county zoning ordinances and
regulations (A.A.C. R18-9-A201(A)(2)(c)).
The above four demonstrations are outside the scope of BADCT and are not further addressed.
Additional information on these demonstrations is available from the referenced rules and
statutes, and the ADEQ=s AAquifer Protection Permits Application Guidance Manual.@ The
ADEQ will use both this AMining BADCT Guidance Manual@ and the AAquifer Protection
Permits Application Guidance Manual@ to evaluate APP applications. In the event of an
inconsistency between this manual and applicable rules and/or statutes, provisions from rules
and/or statutes will prevail.
The AAquifer Protection Permits Application Guidance Manual@ provides procedures for
pre-application meetings and coordination between the ADEQ and the applicant, at the
applicant=s request. This early coordination is strongly encouraged by ADEQ to provide
assurance that the applicant=s efforts are focused on relevant issues and necessary data collection,
including those requirements related to the determination of appropriate BADCT.
BADCT Selection Process Overview
To achieve BADCT, mining facility owners and operators should use demonstrated discharge
control elements utilized on an industry wide basis to limit or, where practicable, eliminate
discharge to aquifers. When considering technologies, processes, operating methods and other
alternatives for purposes of demonstrating BADCT, a facility must be evaluated in terms of 1)
siting, 2) design, construction, and operation, and 3) closure/post-closure. A range of
considerations must be taken into account in demonstrating BADCT for a facility, including
characteristics, water conservation and augmentation, and economic impacts associated with the
implementation of the various design elements being considered.
________________________________________________ INTRODUCTION (3)
Key concepts reflected in this manual regarding determining BADCT for a facility are that:
$ BADCT must be determined on a site specific basis by evaluating the degree that
alternative discharge control systems minimize the addition of pollutants to the
protected aquifer;
$ Negotiation between the applicant and ADEQ is usually necessary because of
subjective judgments inherent in some BADCT analyses. This means that no single
technology or group of technologies can be mandated as appropriate for all discharge
control systems. Rather, multiple DCTs (Demonstrated Control Technologies) may
be appropriately used to arrive at a BADCT design for a specific facility at a given
site. Then, based on a facility=s status as new or existing, the criteria described in
A.R.S. 49-243.B.1 must be applied to that particular site to determine which DCTs
are appropriate for that facility. It is, however, important to note that the DCTs
presented in this manual are simply alternatives which may or may not be required at
any specific facility; and
$ Monitoring is generally not regarded as part of the BADCT design, unless it is
performed as a specific feedback mechanism to adjust the design or operational
aspects of the facility. The reader is referred to the AAquifer Protection Permits
Application Guidance Manual@ for further discussion on monitoring.
A mining APP applicant may choose between two general approaches to demonstrate BADCT:
$ Prescriptive BADCT criteria (provided the criteria have been developed and are
included in this manual); or
$ Individual BADCT criteria.
Either approach has merit and may be applied to different facilities at a given site. Only one of
the approaches can be applied to a specific facility.
The following sections describe the general processes for developing a BADCT demonstration
for a mining facility.
How To Use This Manual
The APP applicant should use this manual as guidance in developing BADCT for a mining
facility for the purposes of fulfilling the application requirements in A.A.C. R18-9-A202(A)(5),
and demonstrating compliance with A.R.S. 49-243.B.1. If any questions arise, do not hesitate to
contact ADEQ Aquifer Protection Program. This manual will also be used by ADEQ personnel
to review BADCT demonstrations and to draft permits.
This guidance manual is subdivided into four parts, each containing several sections to assist the
applicant in selecting the best route to determining BADCT. The General BADCT Information
(4) INTRODUCTION____________________________________
described in Part 1 should be read first, because the principles discussed apply to whichever
process the applicant chooses to comply with the BADCT requirements.
After reading Part 1, and deciding which BADCT process to use, read Part 2 if you are using the
Prescriptive BADCT process, or read Part 3 if you are using the Individual BADCT process.
Part 1, Section 1.1, broadly discusses the two BADCT processes which are available to the
applicant; namely, the APrescriptive@ and AIndividual@ processes. The APrescriptive@ process is a
prescribed approach that utilizes pre-approved DCTs and design criteria to obtain an APP permit,
largely independent of site specific conditions. It should not be confused with APresumptive@
BADCT (as defined in A.R.S. 49-243.01). Pursuant to A.R.S. 49-243.01.A, the Director may
only establish Presumptive BADCT by rule. The AIndividual@ process, on the other hand, is
performance based, and allows the applicant to select from all available DCTs that constitute
BADCT. This process considers site specific characteristics, operational controls, and other
DCTs. The AIndividual@ process allows designs to be tailored to a specific facility and site, and
allows for the distinction between BADCT for new and existing facilities.
Part 1, Section 1.2, describes how site, technical and economic considerations are applied, on an
industry-wide basis, to a BADCT analysis for a specific facility, with discussions of waste types,
process solution characteristics, water resource values, climatic conditions, site factors and
passive containment. Such factors may affect the BADCT selection for a facility seeking an
APP permit.
Part 2 discusses how to select control technologies for the Prescriptive BADCT process that
results in a conservative BADCT, largely independent of its site specific characteristics. Part 2
contains individual sections for the different types of mining facilities (e.g., heap leach pads,
process solution ponds) for which Prescriptive BADCT criteria have been developed. These
sections have been prepared in a stand-alone format, each intended for use in conjunction with
Part 1. For example, if information is required for applying Prescriptive BADCT criteria to a
heap leach pad, the necessary information is contained within Part 1 and Section 2.4, and the
other sections in Part 2 do not need to be consulted. Prescriptive BADCT criteria have been
developed for the following types of mining facilities:
$ Non-Storm Water Ponds (Section 2.2)
$ Process Solution Ponds (Section 2.3)
$ Heap Leach Pads (Section 2.4)
$ Tailing Impoundments (Section 2.5)
Part 3 identifies the specific control strategies or designs that may be used for individual BADCT
for new and existing facilities. Discharge control strategies are discussed in individual sections
for each mine facility type (e.g., heap leach pads, tailing impoundments, etc.). These sections
have also been prepared in a stand-alone format, each intended for use in conjunction with
Part 1. For example, if information for applying individual BADCT to a heap leach pad is
needed, the necessary information is contained within Part 1, and Section 3.2, and the other
sections in Part 3 are not needed. This manual addresses individual BADCT development for the
following types of mining facilities:
________________________________________________ INTRODUCTION (5)
$ Heap Leach Pads (Section 3.2)
$ Dump Leaching Facilities (Section 3.3)
$ In Situ Leaching Facilities (Section 3.4)
$ Tailing Impoundments (Section 3.5)
$ Surface Ponds (Section 3.6)
The fourth part of the manual is the appendices. These are intended as supplementary
information in developing a BADCT demonstration. Appendix A (Comparison of Copper
Leaching Facilities) discusses and compares the principal types of copper leaching methods
practiced in the United States. Appendix B (Solution, Ore and Waste Characterization) provides
guidance on the rationale and the extent of characterization required for solutions, ores and
wastes. These requirements are dependent on the type of discharge being considered. Appendix
B also discusses the various test methods available to the applicant (such as acid-base
accounting, humidity cell tests and leach procedures). Appendix C (Liner Design Principles and
Practice) presents details helpful to the applicant pertaining to liner system types, their design
and maintenance for environmental protection. The customary and appropriate provisions for
construction quality assurance/quality control required in a BADCT demonstration are discussed
in Appendix D (Construction Quality Assurance and Quality Control). In Appendix E,
(Engineering Design Guidance) the engineering design requirements including hydrologic and
stability considerations are described as they may apply to any type of facility and especially as
they relate to tailing impoundments. Finally, applicable federal, state and local permits and
approvals are discussed in Appendix F (Federal, State and Local Environmental Permits).
Facilities Requiring BADCT
One of the fundamental assumptions utilized in developing this guidance manual is that an
applicant has already determined that an APP is needed for the facility in question. The
following facilities may be present at mining, processing, or smelting and refining operations and
are considered, or deemed by A.R.S. 49-241.B, to be categorical discharging facilities requiring
an APP, unless exempt pursuant to A.R.S. 49-250:
$ Surface impoundments(2) including holding, storage settling, treatment or disposal
pits, ponds and lagoons (A.R.S. 49-241.B.1);
$ Solid waste disposal facilities except for mining overburden and wall rock that has
not and will not be subject to mine leaching operations (A.R.S. 49-241.B.2);
$ Injection wells (A.R.S. 49-241.B.3);
$ Mine tailing piles and ponds(2) (A.R.S. 49-241.B.6);
$ Mine leaching operations(2) (A.R.S. 49-241.B.7);
$ Sewage or sludge ponds and wastewater treatment facilities (A.R.S. 49-241.B.11);
$ Septic tank systems with a capacity of greater than two thousand gallons per day
(A.R.S. 49-241.B.8);
$ Facilities which add a pollutant to a salt dome formation, salt bed formation, dry well
or underground cave or mine (A.R.S. 49-241.B.5); and
$ Point source discharges to navigable waters (A.R.S. 49-241.B.10).
(6) INTRODUCTION____________________________________
The APP and BADCT requirements apply to both new and existing mining operations.
The designations Anew,@ Aexisting,@ and Aclosed@ are specifically defined in A.R.S. 49-201,
as follows:
$ New facilities began construction or entered into binding contracts after August 13,
1986. Facilities that have undergone major modifications after August 13, 1986 are
also deemed new facilities.
$ Existing facilities began construction or entered into binding contracts on or before
August 13, 1986. Facilities which ceased operation after January 1, 1986 are also
regarded as existing facilities; they must meet BADCT and other APP requirements,
including notification to ADEQ of closure. Economic considerations are important to
the BADCT process for existing facilities.
$ Closed facilities are those which ceased operation before January 1, 1986 with no
intent to resume operations for which they were intended. Closed facilities are
exempt from the APP requirements; hence, they are not subject to BADCT
requirements.
Some mining facilities may qualify for the following specific exemptions:
$ AMining overburden returned to the excavation site, including any common
material which has been excavated and removed from the excavation site and has not
been subjected to any chemical or leaching agent or process of any kind.@
(A.R.S. 49-250.B.5)
$ ALeachate resulting from the direct, natural infiltration of precipitation through
undisturbed regolith or bedrock if pollutants are not added to the leachate as a result
of any material or activity placed or conducted by man on the ground surface.@
(A.R.S. 49-250.B.9)
$ ASurface impoundments used solely to contain storm runoff, except for surface
impoundments regulated by the federal clean water act.@ (A.R.S. 49-250.B.10)
$ AClosed Facilities. However, if the facility ever resumes operation the facility shall
obtain an aquifer protection permit and the facility shall be treated as a new facility
for purposes of section 49-243.@ (A.R.S. 49-250.B.11)
$ AStorage, treatment or disposal of inert material.@ (A.R.S. 49-250.B.20)
$ AStructures designed and constructed not to discharge, which are built on an
impermeable barrier that can be visually inspected for leakage.@ (A.R.S. 49-
250.B.21)
$ APipelines and tanks designed, constructed, operated and regularly maintained so as
not to discharge.@ (A.R.S. 49-250.B.22)
$ Other miscellaneous facilities as referenced in A.A.C. R18-9-102 and 103.
________________________________________________ INTRODUCTION (7)
Some mining facilities may qualify for a general permit. The APP rules contain 42 general
permits which replace individual permits for several classes of facilities in major industry
groups, including mining and other industrial operations. These general permits rely on clear
technical standards to ensure that a discharging facility does not violate aquifer water quality
standards and that the facility employs BADCT in its design, construction, operation and
maintenance. There are four types of general permits (Types 1, 2, 3 and 4) for which facilities
may qualify. Consult the following rules for the detailed technical requirements: A.A.C. R18-9-
A301 through R18-9-A316 (General Provisions); R18-9-B301 (Type 1); R18-9-C301 through
R18-9-C303 (Type 2); R18-9-D301 through R18-9-D307 (Type 3); and R18-9-E301 through
R18-9-E323 (Type 4).
And, some types of facilities are not required to obtain an APP because they are not considered a
discharging facility under the APP program. A Adischarge@ is defined by A.R.S. 49-201.11 as:
Athe addition of a pollutant from a facility either directly to an aquifer or to the land
surface or the vadose zone in such a manner that there is a reasonable probability that
the pollutant will reach an aquifer.@
Mining operations with activities that are neither categorical, exempt, or general permitted may
be judged to be discharging in accordance with A.R.S. 49-241.A. All facilities that discharge are
required to obtain an APP with BADCT incorporated into their design. If it is uncertain if a
facility needs an APP, ADEQ can be requested, in accordance with A.A.C. R18-9-106, to
determine the applicability of the APP program to the operation or activity. A non-refundable
flat rate fee, in accordance with A.A.C. R18-14-102(C)(3), will be charged for each
determination requested. ADEQ expects, however, that determinations of applicability will be
rare. Applicants are urged to consult the APP rules first, because in almost all cases, the APP
rules clarify whether coverage is required.
In evaluating a determination of applicability, ADEQ may request that the waste be
characterized. Appendix B, Solution, Ore and Waste Characterization, includes guidance that
will be useful for this purpose. If the facility does not discharge, then the facility need not
comply with the APP requirements and no further design or analysis is necessary. If the facility
does discharge, the characterization will be used to properly design the facility to satisfy the
BADCT requirements. The burden of proof lies with the applicant to show that the facility is not
a discharging facility.
PART I
General BADCT Information
_______________________________ GENERAL INFORMATION (1-1)
PART 1 GENERAL BADCT INFORMATION
1.1 THE BADCT PROCESS
When considering technologies, processes, operating methods and other alternatives for purposes
of a BADCT design, a facility must be evaluated in terms of 1) siting; 2) design, construction,
and operation; and 3) closure and post-closure.
Part of the BADCT determination process involves deciding whether to use a “Prescriptive”
approach or a site specific “Individual” approach for determining BADCT pursuant to A.R.S.
49-243.B.1. Both approaches have merit and either may be appropriate for the applicant’s facility.
• The “Prescriptive” approach requires evaluating and selecting a predetermined
discharge control technology as the BADCT design. This approach provides a
simplified method for an APP applicant to propose BADCT that will be acceptable to
the ADEQ. The prescriptive criteria provided in this manual are designed to be
generally conservative, and to minimize the level of site investigation and engineering
evaluations that the applicant will be responsible for completing. The Prescriptive
BADCT criteria are based on the premise of minimizing any discharge beyond the
engineered containment. Therefore, this approach cannot incorporate any natural
discharge attenuation that may occur in the vadose zone below engineered containment
systems.
• The “Individual” approach allows the applicant to evaluate and compare alternatives
(alternative discharge control systems) which combine site characteristics with
demonstrated control technologies (DCTs) that can be applied to arrive at a BADCT
design. This approach provides a method for an APP applicant to utilize a site specific
BADCT design that can incorporate water quality protection characteristics that may
occur due to the climate, vadose zone conditions beneath the facility, operational
procedures, and other factors. While this approach allows the BADCT design to be
optimized compared to the generally conservative Prescriptive BADCT criteria, the
applicant should realize an increased effort will likely be required for site
characterization, facility design, APP application review, etc.
In the following sections, general processes for performing a BADCT evaluation for a facility
are described. Both the Prescriptive and Individual BADCT approaches can be utilized for
different facilities at a given site. For example, an applicant may elect to utilize Prescriptive
BADCT for some site facilities such as ponds and Individual BADCT for other facilities such as
heap leach pads or a tailing impoundment.
Both the Prescriptive and Individual BADCT approaches are based on preventing, or minimizing
to the extent practicable, the loading of pollutants to an aquifer. Attenuation of pollutant
concentrations within the aquifer itself, the point of compliance for water quality standards and
water quality monitoring, and other aspects related to discharge after it encounters the aquifer,
are outside the scope of BADCT for most types of facilities. Figure 1-1 schematically illustrates
the “zones” typically encompassed by Prescriptive and Individual BADCT designs. Exceptions
occur where the aquifer may be part of the BADCT design in the cases of in-situ leaching and
passive containment.
(1-2) GENERAL INFORMATION ________________________________
_______________________________ GENERAL INFORMATION (1-3)
1.1.1 Prescriptive BADCT
Prescriptive BADCT, which is an expedited approach to determining BADCT, allows the
applicant to select specific demonstrated control technologies for certain facilities or facility
types which ADEQ considers to comply with the BADCT requirements. The objective of this
approach is to simplify and expedite the permitting of conventional facilities by minimizing
required information gathering, information review, and negotiations, compared to the site
specific Individual BADCT approach. The Prescriptive BADCT criteria are defined in Part 2 of
this manual.
The following facility types are eligible to utilize the Prescriptive approach:
• Non-Storm Water Ponds;
• Process Solution Ponds;
• Heap Leach Pads; and
• Tailing Impoundments.
If the applicant demonstrates that the design, construction, technology, process, operating
method or other elements meet the prescriptive criteria, or an engineering equivalent, and the
application incorporates these prescriptive criteria, or equivalents, then the applicant will meet
the requirements of A.R.S. 49-243.B.1.
The use of Prescriptive BADCT in an APP application is typically more applicable to small and
medium size mining operations, existing operations undergoing expansion, or existing operations
intending to add facilities.
1.1.2 Prescriptive BADCT Review Process
An application for an APP utilizing Prescriptive BADCT must include a proposal of what
BADCT is at the facility. This proposal should meet the appropriate prescriptive design criteria
for the facility described in Part 2 of this manual. An example Table of Contents for describing
in the APP application how the design meets BADCT requirements is provided in Table 1-1.
Shallow groundwater conditions, if present, must be documented for design considerations, and
may prohibit the use of the Prescriptive BADCT approach.
The presence of certain site specific geologic hazards may also prohibit the use of Prescriptive
BADCT. When process facilities are intended to be located: 1) in areas known to be prone to
excessive subsidence; 2) in the vicinity of active faults; 3) in landslide prone terrain, or 4) in
other locations of known geologic instability, ADEQ may request that an application using
Prescriptive BADCT include studies specific to the hazard(s) present, to assist in determination
of whether or not Prescriptive BADCT is appropriately applied. Provided that the hazard(s)
present will not have a significant potential to impact the effectiveness of the Prescriptive
BADCT design, it will be considered appropriately applied.
(1-4) GENERAL INFORMATION ________________________________
ADEQ’s review begins with an applicability check of the proposed design, and the following
questions are considered: Does this facility qualify for a Prescriptive BADCT approach? Is the
proposed design correctly chosen from the guidance manual and is it correctly applied? If
ADEQ determines that any of the answers are no, the applicant will be notified of the need to
make the appropriate corrections, and resubmit the application. Depending on the degree of
deficiency, this notification and re-submittal process will vary in the degree of formality but in
all cases any final determination must be documented in ADEQ’s files.
_______________________________ GENERAL INFORMATION (1-5)
TABLE 1-1
Example Table of Contents - Prescriptive BADCT Demonstration(1)
1. Introduction
2. Site Criteria
2.1 Relevant Site Characteristics
2.2 Surface Water Controls
2.3 Geologic Hazards
3. Design Construction and Operational Criteria
3.1 Relevant Solution/Effluent Characteristics
3.2 Storage Components
3.3 Site Preparation
3.4 Liner System Specifications
3.5 Stability Considerations
3.6 Facility Operation and Monitoring
4. Relevant Facility Inspection Criteria
5. Relevant Closure and Post-Closure Criteria
Example Appendices:
• Solution, Ore and Waste Characterization Data
• Groundwater Data
• Geologic Hazards Evaluation
• Geotechnical Data
• Surface Water Evaluations
• Construction Procedures and QA/QC
• Slope Stability Evaluations
• Water Balance and Storage Capacity Evaluations
• Equivalent Engineering Evaluations
(1) All applicable sections should clearly state the manner in which Prescriptive BADCT
criteria are satisfied by the proposed design.
(1-6) GENERAL INFORMATION ________________________________
If the APP application and supporting documentation show that the prescriptive criteria are met
and appropriately applied, BADCT demonstration in accordance with A.R.S. 49-243.B.1 and the
APP application requirement of A.A.C. R18-9-A202(A)(5) are deemed satisfied. ADEQ then
proceeds with the processing of the permit application, unless new information warrants an
additional applicability check. This processing includes a determination of completeness for
other parts of the APP application that are not part of BADCT, such as whether or not applicable
water quality standards (AWQS) will be met at the Point of Compliance, and the technical and
financial capability of the applicant.
1.1.2.1 Determination of Prescriptive BADCT
The determination of BADCT using prescriptive criteria for an APP application is based on
meeting the prescribed design, construction, and operating criteria defined in Part 2 of this
manual, or where applicable, by rule (A.R.S. 49-243.01). Since the objective of the Prescriptive
BADCT determination is to simplify and expedite the BADCT review process and therefore the
APP process, the prescriptive criteria are designed to be generally conservative for most site
conditions in order to minimize the need for collection and evaluation of site specific data. Some
site evaluations, however, are still required to provide enough information for determination that
the Prescriptive BADCT is appropriate. As discussed further in Part 2, these include evaluations
of key issues related to site conditions such as identification of flood plains and geologic hazards.
While the Prescriptive BADCT criteria, in part, include specific design criteria for many of the
BADCT elements, engineering equivalents to specific elements are also acceptable. Examples of
engineering equivalents, and supporting information that may be required by ADEQ for each, are
provided in Part 2 (Table 2-1). The ADEQ may require specific supporting evaluations to
demonstrate that the proposed element is at least as protective as the specific Prescriptive
BADCT element it replaces. Engineering equivalents cannot rely on seepage attenuation or
other geologic properties of the vadose zone as part of minimizing aquifer loading.
1.1.3 Individual BADCT Review Process For New Facilities
When submitting an individual application for an APP, an applicant must include a proposed
BADCT design to be used at the facility. A.A.C. R18-9-A202(A)(5) requires that the applicant
submit, in support of the proposed BADCT, a statement of the technology which will be
employed to meet the requirements of A.R.S. 49-243.B.1. This statement shall describe
alternative discharge control measures considered, the technical and economic advantages and
disadvantages of each alternative, and the justification for selection or rejection of each
alternative. The applicant shall evaluate each alternative discharge control technology, relative
to the amount of discharge reduction achievable, site specific hydrologic and geologic
characteristics, other environmental impacts, and water conservation or augmentation
considerations. The economic impact of implementation of Individual BADCT design is further
discussed in Section 1.1.3.7.
_______________________________ GENERAL INFORMATION (1-7)
The development of an Individual BADCT design follows the general principles of engineering
design. Engineering principles are adhered to during the design process involving the designer’s
professional judgment of contingencies, risks and uncertainties based on education and
experience. It is therefore only possible to provide general guidance for the process to be
followed.
Important aspects of developing an Individual BADCT design are:
• Discharge control technologies ordinarily constitute a discharge control system
incorporating engineering features, operational measures and site characteristics to
achieve BADCT; and,
• Alternative designs must be considered to arrive at a BADCT design.
Discharge control technologies are those design elements which can be included to reduce
loading (discharge of pollutants) to an aquifer (e.g., design aspects such as liners, operational
aspects such as desaturated tailing disposal for small projects, and closure aspects such as rinsing
gold and silver ore residue on heap leach pads after leaching is completed).
Alternative designs can include consideration of alternative technologies or alternative design
elements as discussed below, and in some cases, alternative sites. In principle, an Individual
BADCT design is developed through the following approach:
• Development of a range of alternative discharge control systems which may or may
not include different sites on a conceptual basis;
• Screening these alternative systems by estimating the relative degree of discharge
control;
• Selection of the most promising alternative systems for more detailed analysis;
• Refinement of designs for the selected alternative systems;
• Comprehensive estimates of discharge control for the selected alternative systems;
and,
• Selection of BADCT design.
In conducting these analyses, the following steps are required:
• Site selection;
• Development of individual site design (“Reference Design”) based on demonstrated
control technologies and site conditions;
• Estimation of aquifer loading for the Reference Design;
• Alternative design(s) selection as outlined above;
• Estimation of aquifer loading for the promising alternative design(s); and,
• Selection of BADCT design.
Figure 1-2 provides a schematic representation of the process. Each of the steps are described
below. An example Table of Contents for describing in the APP application how the design
meets Individual BADCT requirements is provided in Table 1-2.
(1-8) GENERAL INFORMATION ________________________________
1.1.3.1 Site Selection
Site selection is a powerful tool in developing a protective design. It is sometimes possible to
select a site with outstanding characteristics which will enhance the containment of stored
materials. Maximum advantage should be taken of site selection in development of a
BADCT design.
Site selection can be conducted by the applicant in a formal or informal manner. The formal
process will typically consider sites in areas surrounding the mine and the preferred site will be
selected through a process of fatal flaw screening, site evaluation and ranking, and in some cases,
also limited site investigations and final ranking. Informal site selection is often necessary
because of limited availability of suitable sites in the vicinity of the ore body.
_______________________________ GENERAL INFORMATION (1-9)
TABLE 1-2
Example Table of Contents - Individual BADCT Demonstration(1)
1. Introduction
2. Relevant Site Factors
2.1 Solution, Ore and Waste Characteristics
2.2 Site Characteristics
2.2.1 Surface Hydrology
2.2.2 Hydrogeology
2.2.3 Geologic Hazards
3. Site Selection
3.1 Alternatives
3.2 Evaluation of Alternatives
3.3 Recommended Site
4. Reference Design
4.1 Design
4.2 Construction Considerations
4.3 Operations and Operational Monitoring
4.4 Closure and Post-Closure Considerations
4.5 Estimated Aquifer Loading
4.5.1 Potential Release
4.5.2 Estimated Travel Times to Groundwater Table
4.5.3 Estimated Attenuation of Pollutants
4.5.4 Estimated Aquifer Load
4.6 Estimated Cost of Reference Design
5. Alternative Designs
5.1 Selection of Alternatives
5.2 Screening of Alternatives
5.3 Description of Most Promising Alternative Systems
5.4 Aquifer Loading of Most Promising Alternative Systems
5.5 Estimated Cost of Most Promising Alternative Systems
6. Selection of BADCT Design
6.1 Selection Criteria
6.2 Evaluation of Reference Design and Alternative Systems
6.3 Selected BADCT Design
Example Appendices:
• Solution Ore and Waste Characterization Data
• Groundwater Data
• Geologic Hazards Evaluation
(1) All applicable sections should clearly state the manner in which Individual BADCT
requirements are satisfied by the proposed BADCT design.
(1-10) GENERAL INFORMATION ________________________________
• Geotechnical Data
• Surface Water Evaluations
• Construction Procedures and QA/QC
• Slope Stability Evaluations
• Water Balance and Storage Capacity Evaluations
_______________________________ GENERAL INFORMATION (1-11)
The design documents submitted for APP permitting must describe the site selection process. It
is the applicant’s responsibility to develop this information; ADEQ can only give guidance in
this regard.
1.1.3.2 Development of Reference Design
The development of an individual site design must consider: 1) industry-wide DCTs taking into
account differences in industry sectors; 2) the type and size of the operation; 3) the
reasonableness of applying controls considering the site climatic conditions; and 4) other site
specific conditions. In developing this design, a systems approach should be used. This systems
approach should consider all phases of the project including:
• Site characterization;
• Design, construction and operations; and
• Closure and post-closure.
The demonstrated control technologies for various facilities are described further in Part 3 of this
manual. Table 1-3 provides a “menu” of typical DCTs for each of the above phases.
A Reference Design will typically include DCTs selected from the Table 1-3 menu. For
example, in developing a Reference Design, site specific DCTs will be included such as selection
of a site with low permeability geologic formations, specific design elements such as single
synthetic liners, specific operational technologies such as maintaining the low hydraulic head on
a leach pad, specific operational monitoring proposals such as regular inspections by the facility
operator, and specific closure and post-closure technologies such as bacterial rinsing for a gold
heap leach pad.
In considering the systems approach to development of a Reference Design it is important to
include site characteristics. While it may be important to select a high level of engineered
containment for sites underlain by alluvium and shallow groundwater, the same may not be the
case when the site is underlain by low permeability bedrock and/or deep groundwater (i.e., a
demonstrated geologic barrier). The individual designer will include these considerations in the
systems design based on experience as well as industry wide demonstrated control technologies
which have been applied for similar site conditions. In developing an individual site design the
designer must therefore be encouraged to use creativity to provide the greatest degree of
discharge reduction achievable through application of DCTs and, where practicable, an approach
permitting no discharge of pollutants.
1.1.3.3 Estimation of Aquifer Loading
An evaluation must next be performed to estimate the potential loading of pollutants to the
aquifer as a result of implementing the Reference Design. Loading to the aquifer is used as a
basis for evaluating the impacts of discharge from a facility. This evaluation can be done at
(1-12) GENERAL INFORMATION ________________________________
various levels of sophistication but at a minimum must include the steps outlined below. It is
important that this evaluation should consider the total life cycle of the facility (i.e., operations as
well as closure/post-closure). For example, during operations a slurry deposited tailing
impoundment will contain free water. After closure and during the post-closure period, this free
water may be removed and therefore the driving head for pollutant migration will be eliminated.
_______________________________ GENERAL INFORMATION (1-13)
Page 1 of 4
TABLE 1-3
Examples of Demonstrated Control Technologies
Project Phase Element Demonstrated Control
Technologies (DCT)
Evaluation Procedures to be
Selected From
Site Characterization Solution, Ore and
Waste
Characterization
1) These characterizations are required
to determine the DCTs for other
elements.
1) Procedures to differentiate
between oxide and sulfide
materials.
2) 1312 Leach Procedure.
3) Meteoric Water Mobility.
4) Acid Base Accounting.
5) Humidity Cell Tests.
Geotechnical,
Surface
Hydrology,
Hydrogeologic,
and Geologic
Hazards
Characterizations
1) Siting DCT incorporates selection
of locations with:
• Low permeability geologic
formation
• Deep groundwater tables
• Naturally poor groundwater
quality
• Small contributory watershed.
2) Selection of sites which avoid or
mitigate geologic hazards.
3) These characterizations are required
to determine the DCTs for other
elements.
1) Test pitting, drilling, trenching,
sampling and testing.
2) In-situ tests of, for example,
hydraulic conductivity.
3) Geophysical methods.
4) Water level monitoring.
5) Remote sensing methods.
6) Aerial photography mapping and
interpretation.
7) Site reconnaissance.
8) Other standard hydrologic and
geotechnical field investigation
and data evaluation methods.
Site Preparation 1) Strip vegetation.
2) Excavate and replace weak
foundation materials.
1) Standard construction QA/QC
methods.
Design,
Construction, and
Operations
Surface Water
Control
1) Diversion ditches.
2) Retention structures.
1) Standard hydrologic design
methods.
(1-14) GENERAL INFORMATION ________________________________
Examples of Demonstrated Control Technologies
Project Phase Element Demonstrated Control
Technologies (DCT)
Evaluation Procedures to be
Selected From
Discharge Control 1) DCTs for discharge control vary
significantly depending on the type
and size of the operation and the
reasonableness of applying controls
in arid or semi-arid settings, but
may include:
• Liners for containment.
• Natural containment.
• Leachate collection and
hydrostatic head control
systems consisting of:
- Manufactured or imported
drain rock and perforated
pipes.
- Ore materials satisfying
drainage requirements.
- Granular or synthetic leak
collection layers for pond
liner systems.
• Solution conveyance pipes or
lined channels and storage
capacity.
1) Systems approach to liner system
design (Appendix C).
2) Standard engineering measures for
surface containment.
Stability 1) Specified ultimate slope height.
2) Stability benches.
3) Design to withstand shear forces,
e.g., by compaction, use of
geosynthetics, etc.
4) Control of pore pressures by
drainage.
5) Buttressing.
1) Shear strength analysis.
2) Static stability analysis.
3) Seismic deformation analyses.
_______________________________ GENERAL INFORMATION (1-15)
Examples of Demonstrated Control Technologies
Project Phase Element Demonstrated Control
Technologies (DCT)
Evaluation Procedures to be
Selected From
Operations 1) Conduct operations to minimize
potential for damage to liners at
heap leach sites:
• • Geosynthetic and/or gravel
protective layers.
• • Low ground pressure
equipment.
• • Limit equipment traffic.
• • Load in uphill direction.
• • Limit rate of rise.
• • Limit maximum height.
2) Control solution applications at
heap leach sites:
• • Avoid excessive reagent
concentrations.
• • Avoid application rates or
storage conditions that result in
excessive hydraulic head.
• Sequence leaching activities.
3) Managed tailing deposition:
• • Layered or subareal deposition.
• • Limit size of water pond.
4) Operational monitoring to allow
early detection and correction of
problems.
5) Facility maintenance to assure
performance is consistent with the
design.
1) Consider operational conditions
during design of facility.
2) Visual observations.
3) Survey monuments.
4) Instrumentation.
Closure and
Post-Closure
Physical Stability 1) Surface Water Control to reduce
erosion.
2) Recontouring to control surface
flow.
3) Cover placement (e.g., vegetation or
rock armor) to reduce erosion.
4) Erosion protection of ditches.
1) Stability evaluations.
2) Long-term erosion evaluations.
(1-16) GENERAL INFORMATION ________________________________
Examples of Demonstrated Control Technologies
Project Phase Element Demonstrated Control
Technologies (DCT)
Evaluation Procedures to be
Selected From
Chemical Stability 1) Source control:
• • Ore residue rinsing and/or
detoxification.
• • Ore residue removal.
2) Migration control:
• • Surface grading to enhance
run-off.
• • Surface grading to minimize
run-on.
• • Design cover to minimize
infiltration and enhance
moisture removal (e.g.,
increased evapo-transpiration
by fine-grained soils and/or
vegetation).
• • Cap with low permeability
cover.
3) Interception (e.g., using shallow
trenches; cutoff walls) and water
treatment.
1) Column leach tests.
2) Fate and transport evaluations.
3) Cover water balance evaluations.
_______________________________ GENERAL INFORMATION (1-17)
The steps which should be followed to estimate aquifer loading for the total life cycle of the
facility are as follows:
• Estimate the potential release from the facility by using empirical equations or other
appropriate approximate methods.
• Estimate the travel time to the water table beneath the facility by vertical migration
using groundwater flow calculation methods such as described in Appendix C of
Hutchison and Ellison (1992).
• Estimate attenuation of pollutants in the foundation based on published values or
laboratory test results.
• Estimate the load added to the aquifer of constituents that have the potential to impact
water quality, particularly those for which there are water quality standards.
The purpose of the load estimation to the aquifer is to provide a consistent method to compare
the potential impacts of various designs. It is therefore not intended that this evaluation should
turn into a research project or an advancement of the state-of-the-art. However, consistent and
realistic approaches should be followed.
1.1.3.4 Alternative Design(s) Selection
Alternative design(s) should next be developed and can include the evaluation of alternative
control technologies or design elements for each applicable type of facility (Part 3 summarizes
various demonstrated control technologies for different types of facilities) or, as may be
appropriate, the evaluation of alternative sites. The selection of the alternative design(s) should
be based on the systems approach where control technologies as well as realistic site conditions
are considered.
1.1.3.5 Estimation of Aquifer Loading for Alternative Design(s)
Estimating the aquifer loading for the alternative design(s) follows the same approach as
described above for estimation of aquifer loading for the Reference Design. By following the
same procedures, comparative aquifer loadings from the Reference Design as well as the
alternative design(s) can be developed.
1.1.3.6 Selection of BADCT Design
The final step in developing an individual BADCT design is to make a selection from the
Reference Design and the alternative design(s). The basis for this selection is loading to the
aquifer. The BADCT design will be that design which results in the least amount of pollutant
loading (discharge) to the aquifer. For example if an alternative design results in a lower
pollutant loading to the aquifer, then that design will be selected as the BADCT design instead of
the Reference Design.
In cases where the Reference Design and/or the alternative design result in similar loadings to
the aquifer, and discharges do not contain materials listed in A.R.S. 49-243.I, the design with the
(1-18) GENERAL INFORMATION ________________________________
lowest costs (i.e., capital, operations, closure, post-closure and other applicable costs) may be
selected as the BADCT design. In such cases, negligible loadings can be considered similar
even if the relative difference between loadings is significant (e.g., where loadings from
alternatives are small compared to the highest loading that could still comply with aquifer water
quality standards, the fact that the loading from one alternative may be up to orders of magnitude
smaller may not preclude these loadings from being considered similar). If the discharge
contains materials listed in A.R.S. 49-243.I, the applicant must limit discharges to the maximum
extent practicable regardless of cost.
The BADCT design is therefore selected based on DCTs, a systems approach including site
conditions, and the estimation of aquifer loadings for alternative designs.
The requirement for this individual BADCT evaluation process to be demonstrated in APP
applications is described in regulation as follows (A.A.C. R18-9-A202(A)(5)):
“The applicant shall submit in support of the proposed BADCT a statement of the
technology which will be employed to meet the requirements of A.R.S. 49-243.B. This
statement shall describe the alternative discharge control measures considered, the
technical and economic advantages and disadvantages of each alternative, and the
justification for selection or rejection of each alternative. The application shall evaluate
each alternative discharge control technology, relative to the amount of discharge reduction
achievable, site specific hydrologic and geologic characteristics, other environmental
impacts, and water conservation or augmentation. The economic impact of implementation
of each alternative control technology shall be evaluated on an industry-wide basis. In
addition, a statement for a facility in existence on the effective date of this Article shall
reflect consideration of the factors listed in A.R.S. 49-243.B.1(a) through (h).”
A.R.S. 49-243B.1(a) through (h) includes the following:
(a) “Toxicity, concentrations and quantities of discharge likely to reach an aquifer from
various types of control technologies.
(b) The total costs of the application of the technology in relation to the discharge reduction
to be achieved from such application.
(c) The age of equipment and facilities involved.
(d) The industrial and control process employed.
(e) The engineering aspects of the application of various types of control techniques.
(f) Process changes.
(g) Non-water quality environmental impacts.
(h) The extent to which water available for beneficial uses will be conserved by a particular
type of control technology.”
As discussed in Section 1.1.2, the BADCT demonstration portion of the application can be
deemed complete, and A.A.C. R18-9-A202(A)(5) deemed satisfied without this evaluation where
facilities utilize Prescriptive BADCT.
1.1.3.7 Economic Considerations
In regard to new facilities, A.R.S. 49-243.B.1. directs ADEQ to consider economic impacts of
the application of BADCT with other factors on an industry-wide basis. The determination of
economic impact on an industry-wide basis shall take into account differences in industry sectors
_______________________________ GENERAL INFORMATION (1-19)
(i.e., Copper Sector, Gold Sector, Uranium Sector, etc.), the facility type (i.e., heap leaching,
dump leaching, in-situ, copper oxide leaching, copper sulfide leaching, etc.), the size of the
operation, and the reasonableness of applying controls in an arid or semi-arid setting (gold
mining in Northern California vs. gold mining in Arizona, copper mining in Michigan vs. copper
mining in Arizona, etc.). ADEQ considers that use of a technology at many other similar
facilities in the same industry sector, same type and size, and in the same climatic setting
indicates financial feasibility. As indicated above, if a new facility discharges the pollutants
identified in A.R.S 49-243.I, then that facility must meet the criteria of A.R.S. 49-243.B.1
(BADCT) to limit discharges to the maximum extent practicable regardless of cost.
1.1.3.8 Discussion
It may be beneficial from a design point of view to include elements which are innovative and
therefore may not satisfy the requirement of an industry-wide DCT. In this case, the designer
must demonstrate that such technologies will perform as intended. Such demonstration can be
based on literature reviews, engineering analyses, laboratory and pilot scale testing, or by
providing case histories of analogous applications of the technology.
1.1.4 Individual BADCT Review Process for Existing Facilities
An existing facility is defined in A.R.S. 49-201.14. as one that is neither a new or closed facility
and at which construction began before August 13, 1986. According to A.R.S. 49-201.18, a
closed facility that is reopened does not constitute an existing facility, but is regarded as a new
facility. The distinction between existing and new facilities is important in determining BADCT
for the following two basic reasons:
1) At an existing facility, determining BADCT requires ADEQ and the applicant to
consider potential upgrades to the facility design, and
2) Additional factors for existing facilities apply as listed in A.R.S. 49-243.B.1(a) through
(h), such as, weighing cost vs. discharge reduction, the age of equipment, and the
engineering aspects of the application of various types of industrial and control
processes. Also, the requirement of A.R.S. 49-243.I that a new facility limit discharges
of certain listed organic pollutants to the maximum extent practicable regardless of cost
does not apply to existing facilities.
Note that the option of Prescriptive BADCT also applies to an existing facility. If the facility
meets the prescriptive criteria identified for the specific type of facility in Part 2, no further
demonstration is necessary. Most existing facilities, however, warrant the individual evaluation
process.
There are two major differences in approach mandated for determining BADCT for an existing
facility, compared to that for a new facility. First, existing design and site conditions offer
constraints on what can be achieved with the final BADCT configuration. Second, analysis of
cost vs. discharge reduction applies in determining BADCT. To arrive at a BADCT, the existing
design and its performance become the basis of comparison for judgments about whether or not
to upgrade the design. Possible upgrades must, of course, be limited to those that are feasible
from an engineering standpoint given the age, design, and operational controls of the facility.
(1-20) GENERAL INFORMATION ________________________________
Complicating matters at an existing facility may be the groundwater impact of past operations.
While remedial or mitigative efforts may be needed in areas where groundwater quality does not
conform to Aquifer Water Quality Standards downgradient of a facility (see A.R.S. 49-243.L),
these activities do not constitute part of BADCT for the facility. The reason for this distinction is
that BADCT does not include actions or design features which affect groundwater after
pollutants have been released into it, since discharge has already occurred in those instances.
Thus, while existing groundwater quality may be an indicator of the performance of the current
design, remedial or mitigative technologies do not reduce discharge and should not be considered
in the BADCT evaluation.
There are five basic steps in the existing facility process. Similar to the new facility process
outlined previously, the applicant develops a Reference Design. However, here, the existing
configuration of a facility and site represents its Reference Design. Alternatives to the Reference
Design are then developed and evaluated as outlined by the following five basic steps:
Step 1 Identify current DCTs and site factors;
Step 2 Estimate performance (determine aquifer loading);
Step 3 Identify technically feasible alternative DCTs and assemble them on a candidate list.
Consider water conservation and other environmental factors to reduce or
adjust the list;
Step 4 Use the candidate list to arrive at one or more alternative systems;
Step 5 Weigh cost vs. discharge reduction for each alternative system to arrive at BADCT:
- Calculate improvements in aquifer loading expected from one or more alternative
systems with new DCTs, and
- Determine costs to implement alternative system(s).
1.1.4.1 Steps 1 & 2: Identifying Current Discharge Controls and Assessing Their
Performance - The Reference Design
As with new facilities, BADCT determination for existing facilities depends on an adequate
characterization of the discharge quantity and type. To establish the Reference Design for an
existing facility, the applicant should inventory the discharge controls used in the facility’s
current design. The control processes and technologies can be identified according to the design
elements and site characteristics described in Part 3. Discharge control technologies to consider
include process solution controls in conjunction with: solution, ore and waste characterization;
site preparation; surface water controls; liners; leachate collection systems; stability design;
operational monitoring; closure/post-closure; and site factors. Where original design plans are
lacking, the applicant should develop as-built design information for those aspects of the facility
which have some bearing on discharge rates and characteristics. To save time and effort, and to
promote efficiency, the applicant is encouraged to discuss the level of detail needed with ADEQ
prior to developing as-built drawings.
Once existing control processes are identified, the applicant should evaluate the overall discharge
control performance of the facility. As for the approach for new facilities, the applicant may
assess site factors and their performance for pollutant reduction in the manner presented in
Section 1.2. Where practicable, this step should involve direct measurement of discharge
quantity and quality. Otherwise, the applicant may calculate expected performance based on
_______________________________ GENERAL INFORMATION (1-21)
industry standards for the engineered controls, test data for components, and site specific
characteristics determined from field or laboratory testing. Aquifer loading from the facility for
the existing configuration can be estimated by the same methods used in Section 1.1.3. This
aquifer loading analysis constitutes the performance of the Reference Design.
1.1.4.2 Step 3: Identifying Technically Feasible DCTs for Improvement
The BADCT design for an existing facility may involve instituting additional control
technologies to those in current use. This step in the process involves developing a list of
alternative DCTs that are technically feasible for application at the facility. In many situations,
new controls may not be feasible. For instance, adding a liner to an existing dump leach system
is beyond the realm of normal mine design and operation. In such cases an applicant should
consider other design elements or operational controls discussed below to achieve discharge
reduction.
Working with only technically feasible technologies, the applicant should assemble a focused,
yet complete, list of candidate DCTs for improvement of the existing facility. Ideas for
candidate DCTs may be gained from reviewing the lists of DCTs presented in Part 3. However,
many DCTs identified in Part 3 may not work as “retrofitted technologies.” The following are
types of DCTs which are often easily implemented and may, depending on the facility design
and site, offer considerable improvement in facility performance to control discharge:
• Operational controls - physical and chemical (This includes physical controls such as
modifying solution application cycles and the amount of solution inventory in the
heap or pond storage, and chemical controls such as altering the reagents or reagent
dose rates);
• Run-on and other storm water management controls;
• Closure elements such as removal of free liquids, grading, covering, etc.;
• Containment systems for process solution and other potential pollutant sources; and
• Stability improvements by, for example, berming, benching or regrading.
Aside from technical feasibility, certain other factors may disqualify particular DCTs from
making the candidate list. Water conservation may be a factor for deciding whether or not a
change in discharge control technology is favorable. Simple dilution of a pollutant to achieve
lower discharge concentrations, in itself, may not meet BADCT, nor will technologies that
consume or alter the quality of large quantities of water. However, there may be extenuating
circumstances in which dilution is desirable, such as to facilitate beneficial use of the water or
achieve an environment which could enhance natural treatment.
The applicant should also consider other environmental factors. The use of a new discharge
control technology at an existing facility may have environmental impacts that are not directly
related to aquifer water quality. An example of such a technology is air stripping to remove
volatile organic substances from water and mobilize them in air. These environmental tradeoffs
must be assessed on a case-by-case basis, and judgments about whether they outweigh discharge
reduction are likely to be subjective. Some other common environmental factors that may
require consideration are air quality, noise levels, land use, aesthetics, environmentally sensitive
areas, endangered species, and the potential for disease transmission.
(1-22) GENERAL INFORMATION ________________________________
1.1.4.3 Step 4: Use Candidate List to Arrive at One or More Alternative Discharge
Control Systems
The selection of alternative design(s) should be based on a systems approach where technologies,
as well as site conditions, are considered. The list of alternative DCTs should be used to identify
components that may be incorporated alone or in combination in the existing reference design to
arrive at the alternative design(s). This step in the process involves considerable professional
judgment and the justification for the selected DCTs may require formal exchange of data, and
discussion and negotiation between the applicant and ADEQ, depending upon how obvious the
available choices are.
1.1.4.4 Step 5: Weigh Cost vs. Discharge Reduction by Calculating Aquifer Loading for
Alternative System(s) and Calculating Cost for New DCTs
After selecting alternative design(s) in Step 4, an applicant should prepare additional aquifer
loading calculation(s) using the same considerations as for the Reference Design. Where
additional DCTs are used, their contribution to discharge reduction should be factored into the
aquifer loading calculation(s). Where new DCTs are substituted for existing ones, the estimated
performance of the new DCT should be used in the calculation. The aquifer loading(s) of the
alternative system(s) need to be compared to the Reference Design.
For cost evaluations, the applicant shall compare the total cost/benefit of the application of the
technology with the discharge reduction to be achieved from such application, as noted in A.R.S.
49-243.B.1(b). When calculating the total cost/benefit, the applicant may apply acceptable
discounting methods used for other accounting purposes within the industry.
1.2 USING SITE CHARACTERISTICS AS A PART OF THE BADCT DESIGN
This section, together with Appendix B (Solution, Ore and Waste Characterization), describes
site, technical and economic considerations, on an industry-wide basis, applicable to BADCT
analysis for a specific facility. It includes discussions on waste types and process solution
characteristics, water resource values, climatic conditions, site factors, and passive containment.
Such factors may affect the BADCT selection for a facility seeking an Individual APP.
1.2.1 Waste Types and Process Solution Characteristics
A.A.C. R18-9-A202(A)(4) requires that a person applying for an APP provide a summary of the
known past facility discharge activities and the proposed facility discharge activities indicating:
• The chemical, physical and biological characteristics of the discharge;
• The rates, volumes, and the frequency of the discharge for each facility; and
• The location of the discharge.
All applications should include the characterizations necessary to satisfy the requirements
described above. In some cases (e.g., new facilities), the applicant may not be able to adequately
define the characteristics of the material to be discharged until the facility becomes operational.
_______________________________ GENERAL INFORMATION (1-23)
In such cases, the applicant must design the facility to be compatible with the characteristics of
discharge from similar types of mining facilities. Then, upon start-up, the applicant shall be
required to characterize the discharge. However, a discharge containing organic substances
referenced in A.R.S. 49-243.I must be identified and characterized in order to design the facility
to meet BADCT regardless of cost.
ADEQ will use this information to determine if the proposed facility BADCT is compatible with
the materials to be contained in the facility. This need for compatibility between the DCT and
the waste characteristics is one of the reasons that detailed design specifications for liners and
other elements cannot be uniformly prescribed in this manual. The characterization information
will also be used to evaluate the quality and quantity of the discharge.
In characterizing waste, ore or process solutions that may be discharged, the applicant must
define the waste type or mix of types (solutions, wastewater, sludges, tailing, leached ore, waste
rock, etc.) including the projected or actual leachate composition that will discharge. Discharges
that are not identified will not be incorporated into the permit and will be subject to compliance
actions under APP regulations. ADEQ should be contacted to review the required type and
frequency of characterization for all materials at the facility.
While waste characterization may be appropriate in the case of waste rock or spent ore from a
precious metal leach operation, it is not clear that such characterization is beneficial for copper
leach ore. In acidic copper leach solutions, high acidity and metals concentrations will be
produced (for both oxide and sulfide leach operations) throughout the period of operation, as
well as after operations. In the case of a sulfide leach project, it is difficult to predict how long it
will take to eliminate all the potential for metal and acid leachate because of the ongoing
bacterial action. As a result, characterization of materials to be leached with acidic solutions
may be deferred until closure of the leach facility. Proposals for deferring material
characterization should be presented to ADEQ during the pre-application period.
Below is a tiered list of tests commonly used to characterize materials that may discharge. Other
tests may also be proposed by the applicant or required by ADEQ. When characterizing tailing
or waste rock that may discharge, or “produce” a leachate that may discharge, the applicant
should conduct the appropriate tests listed in Tier #1 (Part A) with additional testing from Tier
#2 (Part A) and Part B as necessary to adequately characterize the material. Similarly, if process
solutions or waste waters may be discharged, then the applicant should submit the information
requested in Part C below. Where necessary, the ore may be characterized in order to assist in
characterizing the potential discharge. Further guidance on waste characterization testing is
provided in Appendix B. Pre-application coordination with ADEQ is strongly encouraged to
finalize characterization testing requirements.
(1-24) GENERAL INFORMATION ________________________________
PART A:
CHARACTERIZATION OF TAILING, SPENT ORE AND WASTE ROCK
TIER #1 Primary Analytical Procedures For Waste Characterization
• Description of mineralogy and lithology of the waste and leached ore;
• Leach Testing (Leach testing should be performed on all materials which may
discharge in order to determine the quality of leachate that may be formed.)
Types of leach testing include:
- SPLP (Synthetic Precipitation Leaching Potential EPA Method 1312),
- Nevada Meteoric Water Mobility Procedure,
- Leachable sulfates and soluble solids,
- Bottle Roll Tests.
• Acid Base Accounting (ABA):
- Predictive Static Tests.
• Physical Characteristic Tests:
- Grain Size Analysis,
- Density,
- Shear Strength.
TIER #2 Miscellaneous Analytical Procedures For Additional Waste
Characterization
• Predictive Kinetic Tests for prediction and acid generating characteristics;
• Analysis of Metals (Total and/or Soluble);
• Analysis of Radionuclides;
• TCLP;
• Miscellaneous Physical Analyses (e.g., Hydraulic Conductivity, Moisture Retention
Capacity).
_______________________________ GENERAL INFORMATION (1-25)
PART B:
CHARACTERIZATION OF ORGANIC WASTES
OR WASTES CONTAINING ORGANICS
• Organic Analyses:
- Total Petroleum Hydrocarbons,
- Polynuclear Aromatic Hydrocarbons,
- Phenol Analyses,
- Volatile Organic Compounds and Carbon Disulfide.
• Hazardous waste determination testing for wastes not exempted by the Resource
Conservation and Recovery Act (RCRA), where applicable.
PART C:
CHARACTERIZATION OF PROCESS SOLUTIONS, WASTEWATERS
AND MINE WATERS
• Metals;
• Major Cations and Anions;
• Physical/Indicator Parameters;
• Reagents and Organics;
• Radiochemicals;
• Cyanide Species;
• Nutrients and Bacteria;
• Miscellaneous; and,
1.2.2 Water Resource Values
As discussed in previous sections, the BADCT determination process is driven by A.R.S.
49-243.B.1 and A.A.C. R18-9-A202(A)(5) The BADCT for a site includes those components of
facility siting, design, construction, operation and closure/post-closure that limit discharge to an
aquifer. Dilution, attenuation, and other factors that effect discharges after reaching an aquifer
are not part of BADCT. Demonstrations related to water quality at the point of compliance
pursuant to A.R.S. 49-243.B.2 and B.3 are separate and in addition to BADCT, and are not
covered in this manual.
Water resource considerations that play a role in BADCT determination are: (1) site surface
water flow characteristics that can effect containment and migration of discharges through the
vadose zone (e.g., surface water run-on and run-off); and (2) potential opportunities for water
conservation or augmentation. The surface water hydrology aspects are discussed further in
Section 1.2.4.4. This section provides the objectives and background to the water resource
conservation considerations.
(1-26) GENERAL INFORMATION ________________________________
A.R.S. 243.B.1 states, in part:
“In determining best available demonstrated control technology, processes, operating
methods or other alternatives the director shall take into account ... the opportunity for
water conservation or augmentation ... .”
A.A.C. R18-9-A202(A)(5)(b) states that an applicant shall submit,
“An evaluation of each alternative discharge control technology, relative to the amount
of discharge reduction achievable, site specific hydrologic and geologic characteristics,
other environmental impacts, and water conservation or augmentation.”
Because mining generally necessitates the use of large quantities of water, conservation plays a
major role in the BADCT design. Water conservation is based on the efficient use of the
available water and recycling of water used in processing. Recycling of process water should be
maximized in the BADCT design. Pumped mine water should be beneficially used wherever
possible.
1.2.3 Climatic Conditions
Precipitation rates and evaporation rates (a function of temperature, humidity, and wind) are the
two primary climatic factors. An applicant wanting to make a demonstration that climatic
factors can reduce potential for discharge should evaluate precipitation and evaporation rates in
conjunction with other site characteristics.
In areas where precipitation rates are high and evaporation rates are low, there is a higher
potential for discharge to impact groundwater. This is because precipitation that does not
evaporate or run off, infiltrates into and then percolates through the mine waste. This infiltration
may be a major transporter of pollutants to the aquifer where no engineered containment is
provided. Generally in these conditions, percolation and subsequent leachate formation are
important and must be accommodated in the design of the facility by incorporating leachate
collection and containment features. Conversely, in arid and semi-arid environments, where
precipitation is low and/or evaporation is high, the potential for surface discharge to impact
groundwater is reduced. It is the applicant’s responsibility to demonstrate what impacts, if any,
climatic conditions will have on the containment provided by the facility.
When analyzing the effects and/or discharge reduction capabilities of climatic factors on
a facility design, it is important that the applicant understands and considers the following site-specific
conditions:
• Precipitation and evaporation rates at the site (or nearest comparable area with historic
data). (A measurement that is relevant to standing water conditions is pan evaporation.
Other methodologies can be applied to estimating soil moisture evaporation
conditions.);
• Surface run-off: The applicant must estimate what percent of precipitation will run off
the facility, and thereby be removed from water balance considerations for the material.
_______________________________ GENERAL INFORMATION (1-27)
The percentage of run-off depends on several factors including amount, intensity and
duration of storm events (consideration should be given to extended periods of
precipitation events during periods of low evaporation, such as winter rains), surface
slope, permeability of surface (e.g., bedrock conditions, compacted surface vs. ripped
surface), etc. Values of run-off can be determined from existing facilities or obtained
using the U.S. Department of Agriculture Soil Conservation Service SCS methodology
(“Urban Hydrology for Small Watersheds”, PB87-101580);
• Moisture storage condition of the material: Two common terms used to define moisture
conditions are saturation (the moisture condition at which all pore spaces are
completely filled with liquid) and specific retention (the volume of liquid remaining in
the previously saturated material after allowing the liquid to drain out of the material by
gravity). Specific retention depends primarily on material grain size, shape and
distribution of pores and structure. For example, fine grained tailing piles may have a
specific retention of as much as 30% moisture by dry weight, while waste rock may
have a specific retention of between 10% (coarse rock with minimal fines) and 20%
(coarse rock with fines and loam). An applicant considering arid climatic conditions as
a demonstrated control technology must, at a minimum, demonstrate that the material
deposited will be at a moisture content below specific retention, or that it will be
deposited in a manner that will cause the material to dry to at least specific retention;
• Infiltration: The rate of infiltration depends on the grain size distribution, the texture
and geometry of the ground surface, the moisture content of the waste material, and the
amount and rate of rainfall. Coarser materials tend to have higher infiltration rates than
fine-grained materials (or surfaces that are highly compacted);
• Percolation: Once fluids infiltrate a material and the moisture content reaches the
specific retention capacity of the material, percolation occurs. Whether percolation
occurs at the facility depends on several factors including material thickness, frequency
and intensity of storm events, “drying” time in between storm events, the amount of
layering and permeability of the material, the amount of vegetation (vegetation reduce
the potential for percolation through evapotranspiration), grain and rock size,
evaporative depth, etc. Methods such as the Hydrologic Evaluation of Landfill
Performance (HELP) water balance model (Federal Environmental Protection Agency)
and other approaches can be used as a guide to evaluate percolation rates;
• Evaporative depth: Evaporative depth is the depth to which evaporation can occur.
Beyond this depth, evaporation cannot practicably remove moisture that has infiltrated.
This depth is a function of material grain size and density (void space), extent and type
of vegetation, and climatic conditions; and
• Wind: Wind should be considered in the design of a facility because wind increases the
evaporation. The applicant must also take into account over-spray problems and
freeboard design (wave action) when constructing a facility in an area prone to high
speed winds.
If climatic factors are to be used in considering DCTs for a given facility, water balance
calculations must be conducted. It is strongly recommended that water balance calculations be
conducted with input from ADEQ to help assure that acceptable methods are used.
(1-28) GENERAL INFORMATION ________________________________
1.2.4 Site Factors
Site specific factors that may be considered part of the BADCT determination, along with their
data requirements, are discussed in this section. The following discussions do not cover all site
factors relevant to an APP application, but only those relative to BADCT determination. The
applicant may need to gather additional site specific information under the hydrogeologic-study
portion of an APP application to determine the point of compliance, likelihood of compliance
with aquifer standards, alert levels, monitoring requirements, and the discharge impact area. The
“Aquifer Protection Permits Application Guidance Manual” discusses these aspects in more
detail. Applicants are strongly encouraged to meet early with ADEQ and submit a proposal for
the hydrogeologic study. ADEQ’s comments on the workplan and the negotiations with ADEQ
will save much time and effort throughout the BADCT and APP application process.
For mining projects, siting is often dictated by the ore body configuration and local topography.
However, for certain facets of the surface operation, such as location of tailing impoundments,
dump leach and heap leach facilities, etc., limited alternative sites may be available. Site
selection and site characteristics will greatly influence individual BADCT determination since it
is site specific. To a great extent, the site will control the design of the facility.
Site selection influences the design of a facility in that each design element must be adapted, or
fit, to the dimensions, layout and characteristics of the chosen site. The adaptation to the site
affects the performance of the particular design component being used. In selecting a site, an
investigation program needs to be developed and implemented. Much has been published on site
investigation methods and there are numerous investigation approaches. General approaches
available may include:
• Remote sensing;
• Geophysical methods;
• Drilling and sampling;
• Test pits and trenches;
• Laboratory testing;
• In-situ testing; and,
• Monitoring wells and groundwater sampling.
The designer must determine the appropriate investigative methods for selecting a site. The
methods may vary from site to site but the following is a suggested approach.
• Conduct a preliminary study. Review existing geologic and hydrologic information
(e.g., available through libraries, USGS, universities, project files, etc.) including
reports, maps, aerial photos, etc.
• Conduct field reconnaissance of the area. Compare this information with any existing
information.
• Conduct initial investigations and tests, as needed, to augment existing data. Initial
investigations and tests may include: surface mapping; subsurface geotechnical,
geologic and hydrogeologic investigations using test pits or trenches, soil or rock
borings, geophysics, etc.; laboratory testing of soil and rock samples for physical and
geochemical properties; and other efforts, as required to develop the facility design and
supporting evaluations.
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• Review results of initial investigations and tests, determine if additional work is
required to support the development of the design and supporting evaluations (e.g., a
higher level of field mapping, additional site specific tests, etc.), and conduct additional
investigations and tests, as needed.
Examples of site characteristics which may be considered in the ultimate design are summarized
below. These examples are not intended to cover all site aspects of a permit application.
1.2.4.1 Topography
Identifying the topography and surface characteristics of a site is a crucial step in designing a
facility to minimize potential discharge, and to protect human health and the environment.
Tailing, dump leach and heap leach facilities, for example, located on relatively steep topography
underlain by low permeability geologic formations, may benefit from a natural high rate of
drainage that can occur under the tailing, dump leach or heap leach material. This is because of
the presence of steep slopes and limited potential for infiltration into the underlying geologic
formations. Steep topographic terrain is also generally associated with outcropping bedrock
and/or shallow alluvium.
Lining of slopes steeper than 2(H):1(V) has not been practiced on an industry wide basis,
especially for high slopes, due to high induced shear stresses and the possibility of failure of the
underlying geologic materials. Liners can be safely designed for slightly flatter slopes ranging
from 2:1 to 2.5:1 for landfills and on embankment faces. Lining of slopes steeper than 2.5:1 can
be considered provided the applicant has considered the above factors, amongst others, and can
demonstrate the adequacy of the design. However, at larger mining facilities, the height and
steepness of the slope may be limited by 1) allowable tensile stresses in the liner, 2) the capacity
of anchor trenches at the top of the slopes, and 3) the stability of any LCRS system or liners
placed on top of the primary liner.
Stability can be improved by constructing a “buttress” on a flatter slope, benching or the
application of fill materials to reduce the slope. Textured or sprayed-on liners may also be
applicable.
Facilities located on relatively flat terrain do not, on their own, benefit from higher drainage rates
and generally encounter greater soil depths to bedrock. This type of topography is generally
suitable for liner application and such sites may benefit from the presence of naturally occurring,
low permeability material within the vadose zone beneath the facility.
Other topographic factors to consider include the existing containment offered at the site (e.g.,
valley fills, canyons, within existing pits), the characteristics of the natural soils (e.g., low
permeability clay, high permeability gravel), and availability of low permeability borrow soils
for liner construction.
Information to evaluate topography and surface characteristics can be obtained from topographic
maps, field surveys, aerial photos, USGS, Soil Conservation Service reports, etc.
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1.2.4.2 Geology/Stability
To determine how geologic conditions may affect the Individual BADCT design for a facility,
the applicant should extensively evaluate the associated physical, hydraulic and geochemical
properties.
Specific information that may be appropriate to address, and that may be required for an APP
application utilizing Individual BADCT, includes:
• Structural Geology: The degree to which geologic structures may affect the Individual
BADCT design depends on the amount of reliance being placed on geologic
containment. Information on major geologic structures can be identified using geologic
maps, aerial photographs, and existing geologic reports, etc. Detailed onsite geologic
mapping or field investigation programs are required to evaluate site specific structures.
The types of structures that need to be considered include:
- Faults must be considered in the design of any facility because they affect
stability.
- Other structures, such as anticlines and synclines which affect rock strata
orientation, can influence the rate and direction of liquid migration through the
vadose zone and may be important in designing leak detection systems.
- Fracture systems in bedrock can be important in determining seepage rates and
velocities, and the location of monitoring systems.
- Various other geologic structures or discontinuities can affect the areal continuity
of low permeability layers.
• Lithology: Lithology is the physical and mineralogic makeup of geologic materials,
including both unconsolidated deposits (e.g., alluvium) and bedrock. Important
lithologic considerations include:
- Horizontal and vertical variations in lithology that cause permeability to vary and
which can affect the degree of natural containment provided by the site.
- Subsurface strength properties that can affect the long-term integrity of the
facility (e.g., settlement potential) and seismic stability.
- The depth to bedrock, degree of subsurface stratification, and variations in strata
characteristics, can be important to the design of a facility.
- Certain alluvial materials and rock types may, by themselves or possibly in
combination with planned facility operations, possess geochemical characteristics
that contribute to a reduction of discharge and/or limit pollutant migration by
attenuation.
The following are representative methods for determining permeability; site specifics will
determine which methodologies are applicable:
• Soil and rock classification based on subsurface lithologic logs and the use of literature or
other available information to determine approximate permeability values;
• Field permeability testing, including pump tests, packer tests, and other in-situ tests;
• Laboratory grain size analyses and permeability tests;
• Borehole and surface geophysical surveys to define lithologic boundaries, and to
characterize the distribution of permeability.
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The effects of scale should be considered in interpreting results of permeability testing. The
permeability measured in isolated borehole packer tests (e.g., local permeability) may vary from
the permeability of the larger scale rock or soil mass (bulk permeability). This is due to
differences in the persistence, character and interconnectivity of the fractures near the boreholes
as compared to the rock mass or due to heterogeneity in soil masses. It is also important to
consider possible horizontal and vertical variations in permeability (i.e., does permeability
decrease or increase between varying lithologies or with depth) and how the local and regional
groundwater regimes at the site are affected.
1.2.4.3 Soil Properties
Soil is generally characterized by relatively high organic content, biologic activity by roots and
microorganisms, and concentration of weathering products left by leaching, evaporation or
transportation. Soil properties may affect discharge from a facility by physical, chemical and
biologic interaction with a pollutant(s).
Soil properties with potential to affect discharge include: type, distribution and thickness,
structure, grain-size distribution, organic carbon content, chemical composition, mineralogy,
cation exchange capacity, specific surface area and permeability. The applicant should evaluate
any changes to soil characteristics that may result from interaction with the discharge. If soil
characteristics are to be used for attenuation, the attenuation capacity of the material must be
predicted using literature data, or laboratory or field tests.
In addition to analyzing the ability of soil properties to affect the quantity and/or quality of a
potential discharge, shear strength must be analyzed to support stability analyses.
Soil tests and data which may be useful in an Individual BADCT determination include:
• Studies of degradation of pollutants in the soils;
• Batch or column tests to react a simulated discharge with site soils to determine
attenuation capacity;
• Infiltration tests;
• Permeability tests;
• Chemical analyses (pH, EC, inorganic analyses, organic analyses);
• Material property tests (grain size analyses, moisture content, bulk density, Atterberg
Limits);
• Maps of soil distribution and depth;
• Soil boring logs;
• Other pertinent soil information including reference to pollutant attenuation research.
1.2.4.4 Surface Hydrology
If surface water enters waste or processing facilities, leachate can be generated. A key to
controlling leachate generation is to design, construct, operate and close facilities in a manner
that minimizes the potential for contact of surface water with pollutants and excludes surface
water from areas where infiltration may affect groundwater quality. The configuration of surface
(1-32) GENERAL INFORMATION ________________________________
water control systems for a mining facility depends on the climate and topography of the site
area. Computer models may guide the assessment of surface water effects and the need for
surface water control systems. County flood maps may also be helpful.
In general, surface water should be diverted around and drained from areas where facilities are
located using engineered features such as diversions and/or retention structures. Diversions
and/or retention structures are usually designed to minimize run-on to the facility. This
preserves containment integrity and limits the amount of water that may contact process reagents
or other sources of potential pollutants. In some cases, drainage controls may also be necessary
to protect against inundation of the facility and nearby low areas where infiltration may
contribute to pollutant transport in the vadose zone. This can typically be achieved by providing
protective berms or dikes.
The design of surface water control systems is influenced by: precipitation (amount, intensity,
duration, distribution), watershed characteristics (size, shape, topography, geology, vegetation),
run-off (peak rate, volumes, time distribution) and degree of protection warranted.
Timely maintenance is necessary for the continued satisfactory operation of surface water control
systems. The principal causes of failure of surface water diversions and/or retention structures
are inadequate design peak flow capacity, channel and bank erosion, sedimentation, and
excessive growth of vegetation reducing the flow capacity. It is recommended that free-draining
features (e.g., ditches and dikes) be capable of handling the design peak flow and that
impounding features be designed to handle the design storm volume which occurs over a
duration resulting in the maximum storage requirement (ADEQ may approve other design
criteria). Evaluation of these design peak flows and storm volumes is discussed in Appendix E
(Engineering Design Guidance).
Data that may be presented to evaluate the need for surface water control include:
• Location of any perennial or ephemeral surface water bodies;
• Rates, volumes, and directions of surface water flow, including hydrographs, if
available;
• Location of 100-year flood plain;
• Site topography;
• Historical precipitation data.
Any activities in, or discharges to, waters of the United States require 401 Certification with
ADEQ, and may require notification to the Army Corps of Engineers for a 404 Permit, the EPA
for a 402 Permit, and/or the respective County Flood Control District. Additional information
regarding these permits and certifications is presented in Appendix F (Federal, State and Local
Environmental Permits).
1.2.4.5 Hydrogeology
Site characteristics are a part of BADCT insofar as they control the quality and/or quantity of
discharge before it reaches groundwater. Potentially important hydrogeologic characteristics
include vadose zone properties that may help to limit discharge to the aquifer. Dilution,
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attenuation and other factors that affect discharges after reaching an aquifer are not normally an
inherent part of BADCT.
The exceptions, where characteristics within the aquifer may be an inherent part of BADCT, are
the case of in-situ leaching of an ore body and passive containment. In-situ leaching is defined
as the underground injection of solutions into an ore body in-place for the purpose of extracting
the mineral commodity. In-situ leaching is discussed in Section 3.4. Passive containment is
defined by regulation and is discussed in Section 1.2.5.
The remainder of this section addresses vadose zone hydrogeology that may be important to
BADCT for mining operations.
Properties of the vadose zone, the unsaturated zone between the land surface and the saturated
zone or maximum groundwater table (Figure 1-1), may affect the behavior of a discharge in a
number of ways. For example, physical properties of the vadose zone, like the presence of high
permeability layers and geologic structures (e.g., faults, fracture zones), may increase movement
of a discharge to groundwater. Conversely, the presence of impervious layers and geologic
structures (e.g., clay seams, strata boundaries) may retard the movement of a discharge to
groundwater or cause the presence of perched water tables; fine grained layers within the zone
may physically remove some types of pollutants; and the decrease in bedrock permeability with
depth may reduce the possibility of discharge reaching groundwater. Also, chemical and/or
geochemical reactions between the discharge and materials in the vadose zone may alter or
remove some pollutants; or biodegradation due to microbial interaction with the pollutant may
degrade the pollutant.
If the vadose zone consists of layers or lenses of different materials, such as stratified soil
horizons or rock units, the properties of each unit must be considered separately in addition to
describing the general properties of the vadose zone. The applicant should identify lateral and
vertical extent of the geologic units and the type of contacts between the units (e.g., gradational,
fault, unconformity, facies change). Perched water tables within the vadose zone may be
a consideration.
The attenuation of chemical constituents in soil and rock is a valid consideration that can be
factored into site specific evaluations. If vadose materials are to be used for attenuation, the
attenuation capacity of the material must be predicted. Below is a brief description of the four
major types of attenuation mechanisms. This is further explained in “Mine Waste Management,”
Chapter 5 (Hutchison and Ellison, 1992).
• Physical Mechanisms: Physical mechanisms include filtration, dispersion, dilution
and volatilization.
• Physiochemical Mechanisms: Physiochemical mechanisms are dependent on both
physical and chemical conditions and can include adsorption and fixation.
• Chemical Mechanisms: Chemical mechanisms are dependent on the chemical
interaction of an element or mineral with the soil or pore water and includes
solution/precipitation of compounds or the increase/reduction in toxicity of a
constituent by changing its valence state, or the removal/addition of ions by cation
exchange.
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• Biological Mechanisms: Biological mechanisms include biodegradation of a chemical
into the basic oxidation product, bacterial consumption of the chemical or cellular
uptake.
Additional data which may be submitted to characterize the vadose zone or any unit of the
vadose zone for consideration as a part of BADCT design may include:
• Detailed lithologic logs of borings and/or well logs that describe:
- rock type,
- grain-size distribution,
- stratigraphy,
- type and degree of cementation, and
- thickness of units;
• Description of the structural geology including:
- faults,
- fractures,
- joints,
- folds, and
- bedding orientation;
• Geologic maps and cross-sections which identify:
- stratigraphic or formation contacts, and
- structural geology;
• Borehole geophysical logs;
• Surface geophysical surveys;
• Physical properties including:
- horizontal and vertical permeability,
- dispersivity,
- porosity (primary and secondary),
• Chemical analyses (pH, EC, neutralization potential, inorganic and/or organic
analyses);
• Results of batch or column tests showing quality of discharge after reacting with vadose
zone material and quality of vadose zone material after reacting with discharge;
• Material property tests (grain size analyses, moisture content, Atterberg Limits,
maximum density);
• Analyses of fluid movement and/or chemical transport through the vadose zone.
Supportive data may be obtained from:
- lysimeters,
- neutron log measurements,
- observation wells,
- packer tests, and/or
- analytical or numeric simulations.
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Depth to groundwater or the thickness of the vadose zone may be a factor in determining
BADCT. The degree of discharge reduction provided by depth will depend on several variables
including: depth to the anticipated maximum groundwater elevation, the volume and rate of
discharge, the properties of the pollutants in the discharge, the properties of the vadose zone, and
the length of time a discharge may continue. Any considerations of depth to water as a part of
BADCT will have to show how the hydrologic and geochemical characteristics of the vadose
zone in conjunction with its thickness will affect discharge.
Data for evaluating depth to water may include:
• Static water elevation measurements (including date of measurement, location of well,
and elevation of measuring point);
• Well hydrographs to document long term and seasonal trends;
• Location of pumping wells in vicinity of measured well;
• Well construction data (including total depth and location of perforations);
• Geophysical surveys such as seismic and resistivity.
1.2.4.6 Barriers
Hydraulic barriers (e.g., dewatered open pits, or quarries) and physical barriers (e.g., pit walls,
quarries, subsidence zones, or slurry walls) can function as downgradient interceptors of
groundwater flows, seepage in the unsaturated zone and/or surface flows. For example, steeply
sloping surfaces, depressions or openings created by open pit or underground mining can
function as downgradient interceptors of lateral seepage from a facility. Cones of depressions in
groundwater or slurry walls can be used to contain in-situ leach solutions.
Except for in-situ leaching, the use of a hydraulic or physical barrier as a consideration in
BADCT design is appropriate only in the context of discharge reduction prior to a pollutant
reaching an aquifer. For facilities other than in-situ leaching, use of barriers to control pollutants
after reaching the aquifer or to control impacted groundwater may not be used as a part of
BADCT unless the physical barrier also functions as passive containment (see Section 1.2.5).
1.2.5 Passive Containment
A discharging facility at an open pit mining operation shall be deemed to satisfy BADCT
requirements of A.R.S. 49-243.B.1. if the ADEQ determines that both of the following
conditions are satisfied (A.R.S. 49-243.G):
1. “The mine pit creates a passive containment that is sufficient to capture the pollutants
discharged and that is hydrologically isolated to the extent that it does not allow
pollutant migration from the capture zone. For purposes of this paragraph, “passiv