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EPA 821-R-00-007
COAL REMINING
BEST MANAGEMENT PRACTICES
GUIDANCE MANUAL
MARCH 2000
Office of Water
Office of Science and Technology
Engineering and Analysis Division
U.S. Environmental Protection Agency
Washington DC, 20460
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Coal Remining BMP Guidance Manual
Acknowledgments
This manual was developed under the direction of William A. Telliard of the Engineering and
Analysis Division (BAD) within the U.S. Environmental Protection Agency's (EPA's) Office of
Science and Technology (OST). The manual was made possible through a cooperative team
effort. EPA gratefully acknowledges the contribution of the team members involved in this
effort (Jay W. Hawkins of the Office of Surface Mining Reclamation and Enforcement and Keith
B.C. Brady of Pennsylvania's Department of Environmental Protection) for the countless hours
spent and determination in bringing this effort to completion. Their commitment and dedication
to this product was key to the Office of Water's mission of providing guidance and technical
support to its stakeholders. EPA also wishes to thank DynCorp Information and Enterprise
Technology for its contributions and invaluable support, and the Interstate Mining Compact
Commission and its member states for extensive information and data collection activities in
support of mis effort.
Disclaimer
The statements in this document are intended solely as guidance. This document is not intended,
nor can it be relied upon, to create any rights enforceable by any party in litigation with the
United States. EPA may decide to follow the draft guidance provided in this document, or to act
at variance with the guidance, based on its analysis of the specific facts presented. This draft
guidance is being issued in connection with the proposed amendments to the Coal Mining Point
Source Category. EPA has solicited public comment on the information contained in the
proposal. This guidance may be revised to reflect changes in EPA's approach. The changes in
EPA's approach will be presented in a future public notice.
The primary contact regarding questions or comments to this manual is:
William A. Telliard
Engineering and Analysis Division (4303)
U.S. Environmental Protection Agency
Ariel Rios Building, 1200 Pennsylvania Avenue, N.W.
Washington, DC 20460
Phone: 202/260-7134
Fax: 202/260-7185
email: telliard.william@epamail.epa.gov
Acknowledgements
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Coal Remining BMP Guidance Manual
Acknowledgments
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Coal Reminins BMP Guidance Manual
TABLE OF CONTENTS
Page
SECTION OUTLINE i
LIST OF TABLES ix
LIST OF FIGURES ''''' xiii
GLOSSARY AND ACRONYMS '.'.'.'.'.'
EXECUTIVE SUMMARY xxvii
INTRODUCTION '. !
INTRODUCTION TO BEST MANAGEMENT PRACTICES 21
Section 1.0 Hydrologic and Sediment Control BMPs i-i
1.1 Control of Infiltrating Surface Water 1-3
1.2 Control of Infiltrating Groundwater 1-31
1.3 Sediment Control and Revegetation 1-69
Section 2.0 Geochemical Best Management Practices 2-1
2.1 Sampling ; 2-5
2.2 Alkaline Addition 2-29
2.3 Induced Alkaline Recharge 2-63
2.4 Special Handling 2-79
2.5 Bactericides " 2-127
Section 3.0 Operational Best Management Practices 3-1
Section 4.0 Passive Treatment 4-1
Section 5.0 Integration of Best Management Practices 5-1
Section 6.0 Efficiencies of Best Management Practices 6-1
Section 7.0 Best Management Practices - Costs 7-1
APPENDICES
Appendix A: EPA Coal Remining Database - 61 State Data Packages A-l
Appendix B: Pennsylvania Remining Site Study B-l
Appendix C: Interstate Mining Compact Commission Solicitation Sheet Response
Summary C_l
Table of Contents
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Coal Remitting BMP Guidance Manual
Table of Contents
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Coal Remining BMP Guidance Manual
Section Outline
Introduction 1
Environmental Conditions 1
Waters Impacted by Pre-SMCRA Mining 1
303(d) List 3
Abandoned Mine Land Program and AMLIS 4
Industry Profile 7
Regulatory History 7
Remining 9
Existing State Remining Programs 15
Introduction to Best Management Practices 21
Site Characteristics and BMP Selection 24
Regional Differences 26
BMP Implementation 36
Verification , 37
References 39
Section 1.0 Hydrologic and Sediment Control BMPs 1-1
Introduction 1-1
1.1 Control of Infiltrating Surface Water 1-3
Theory 1-3
Site Assessment - Backfill Testing .- 1-6
1.1.1 Implementation Guidelines 1-6
Regrading Abandoned Mine Spoil 1-7
Installation of Surface Water Diversion Ditches 1-9
Low-Permeability Caps or Seals .1-11
Revegetation 1-14
Stream Sealing 1-15
Design Criteria 1-17
1.1.2 Verification of Success or Failure 1-18
Implementation Checklist 1-20
1.1.3 Case Studies 1-21
Case Study 1 1-22
Case Study 2 1-23
Case Study 3 1-26
1.1.4 Discussion 1-29
Benefits 1-29
Limitations 1-29
Efficiency 1-29
1.1.5 Summary 1-30
1.2 Control of Infiltrating Groundwater 1-31
Theory 1-31
Table of Contents
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Coal Returning BMP Guidance Manual
Site Assessment 1-33
1.2.1 Implementation Guidelines 1-34
Daylighting of Underground Mines 1-34
Sealing and Rerouting of Mine Water from Abandoned Workings .. 1-39
Highwall Drains 1-44
Pit Floor Drains 1-47
Grout Curtains 1-50
Ground Water Diversion Wells 1-53
Design Criteria 1-55
1.2.2 Verification of the Degree of Success or Failure 1-56
Daylighting 1-57
Sealing 1-57
Drains 1-57
Grout Curtains 1-58
Diversion Wells 1-58
Implementation Checklist 1-59
1.2.3 Case Studies , 1-60
Case Study 1 '. 1-60
Case Study 2 1-64
1.2.4 Discussion '. 1-65
Benefits 1-65
Limitations 1-65
Efficiency 1-66
1.2.5 Summary 1-67
1.3 Sediment Control and Revegetation : 1-69
Theory 1-69
Site Assessment 1-70
1.3.1 Implementation Guidelines : 1-72
Site Stabilization , 1-75
Revegetation '. 1-75
Direct Revegetation 1-78
Channel, Ditch, and Gully Stabilization '. 1-79
Channel Linings 1-80
Check Dams 1-81
Silt Fences 1-83
Gradient Terraces 1-84
Design Criteria 1-84
1.3.2 Verification of Success or Failure 1-86
Implementation Checklist 1-86
1.3.3 Literature Review/Case Studies 1-88
Case Study 1 1-88
Case Study 2 1-89
1.3.4 Discussion 1-92
Benefits 1-92
Limitations 1-93
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Coal Reminine BMP Guidance Manual
1.3.5 Summary 1-93
References 1-94
Section 2.0 Geochemical Best Management Practices 2-1
Introduction . 2-1
2.1 Sampling 2-5
Introduction 2-5
Acid-Base Accounting 2-6
Components of ABA 2-6
Paste pH 2-7
Percent Sulfur 2-7
Fizz Rating 2-10
Neutralization Potential 2-11
Net Neutralization Potential 2-11
Information Needed to Conduct an Overburden Analysis 2-12
Preparing for Overburden Analysis Sampling 2-14
Areal Sampling - A Survey of State Practices 2-14
Operational Considerations 2-18
Stratigraphic Variation 2-18
Representative Samples 2-18
Sample Collection and Handling 2-20
Sample Collection 2-20
Air Rotary (Normal Circulation) 2-20
Air Rotary (Reverse Circulation) 2-21
Diamond Core .- 2-21
Augering 2-23
Highwall Sampling 2-23
Sample Description (Log) 2-23
Sample Preparation and Compositing 2-24
2.2 Alkaline Addition 2-29
Theory 2-29
2.2.1 Implementation Guidelines 2-33
Alkaline Materials 2-35
Limestone and Limestone-Based Products 2-36
Coal Ash 2-37
Other Alkaline Additives 2-39
Application Rates 2-40
Materials Handling and Placement 2-43
Alkaline Redistribution 2-45
Alkaline Addition as a Best Management Practice on Shallow
Overburden 2-46
2.2.2 Verification of Success or Failure 2-47
Implementation Checklist 2-47
2.2.3 Literature Review and Case Studies 2-48
Case Study 1 1 2-51
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Coal Reminine BMP Guidance Manual
Case Study 2 2-54
Case Study 3 2-55
Case Study 4 2-58
2.2.4 Discussion 2-59
Benefits 2-59
Limitations 2-60
Efficiency 2-60
2.2.5 Summary 2-61
2.3 Induced Alkaline Recharge 2-63
Theory \\ 2-63
2.3.1 Implementation Guidelines 2-64
2.3.2 Verification of Success or Failure 2-65
2.3.3 Case Studies 2-66
Case Study 1 2-66
Case Study 2 2-70
Case Study 3 2-74
2.3.4 Discussion 2-74
Benefits 2-74
Limitations 2-75
Efficiency 2-76
2.3.5 Summary 2-77
2.4 Special Handling 2-79
Theory 2-83
Sampling and Site Assessment 2-86
Geologic and Geochemical Considerations 2-87
Hydrogeologic Considerations 2-87
Operational Considerations 2-90
2.4.1 Implementation Guidelines 2-90
Geologic and Geochemical Considerations 2-90
Hydrogeologic Considerations 2-91
Operational Considerations 2-92
Discussion of Theory 2-96
Placement above the water table and encapsulation 2-96
Capping 2-102
Handling of Acid Materials Using the Submergence or "Dark and Deep"
Technique 2-104
Handling of Acid and Alkaline Materials Using Blending Techniques and
Alkaline Redistribution 2-107
Operational Considerations 2-109
2.4.2 Verification of Success or Failure 2-111
Implementation Checklist , 2-111
2.4.3 Case Studies 2-112
Case Study 1 2-112
Case Study 2 '. 2-117
Case Study 3 \ 2-117
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Coal Reminins BMP Guidance Manual
Case Study 4 2-118
Case Study 5 ; 2-118
Case Study 6 2-120
2.4.4 Discussion 2-120
Benefits 2-121
Limitations 2-121
Efficiency 2-122
2.4.5 Summary 2-124
2.5 Bactericides 2-127
Introduction 2-127
Theory 2-127
Site Assessment 2-129
2.5.1 Implementation Guidelines 2-130
2.5.2 Verification of Success or Failure 2-131
2.5.3 Literature Review/Case Studies 2-131
Case Study 1 ... 2-135
Case Study 2 2-136
Case Study 3 2-137
Case Study 4 2-137
Case Study 5 2-137
Case Study 6 2-138
2.5.4 Discussion '. 2-138
Benefits 2-139
Limitations 2-139
Efficiency 2-139
2.4.5 Summary 2-140
References 2-140
Section 3.0 Operational Best Management Practices 3-1
Introduction 3_1
Theory 3_j
Site Assessment 3_2
3.1 Implementation Guidelines 3.4
Rapid Mining and Concurrent Reclamation 3-4
Off-Site Disposal of Acid-Forming Materials 3-8
Auger Mining 3_11
Stockpiling of Coal 3-12
Consideration of Overburden Quality 3-14
Coal Refuse Reprocessing or Cogeneration Usage 3-16
Maximizing Daylighting 3_18
Implementation Checklist 3_22
3.2 Verification of Success or Failure 3-24
Implementation Checklist 3_27
3.3 Literature Review / Case Studies 3-28
3.4 Discussion 3_29
Table of Contents v
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Coal Remining BMP Guidance Manual
Benefits 3-29
Limitations r 3-30
Efficiency '. 3-30
3.5 Summary . 3-31
References - - 3-32
Section 4.0 Passive Treatment Technologies 4-1
Introduction 4-1
Theory '. 4-2
Site Assessment 4-3
4.1 Implementation Guidelines 4-4
Anoxic Limestone Drains 4-4
Constructed Wetlands 4-9
Successive Alkalinity-Producing Systems 4-14
Open Limestone Channels 4-18
Oxic Limestone Drains '. 4-21
The Pyrolusiteฎ Process 4-22
Alkalinity-Producing Diversion Well 4-24
Design Criteria 4-28
4.2 Verification of Success or Failure 4-28
Implementation Checklist 4-29
4.3 Case Studies '. 4-32
Case Study 1 4-32
4.4 Discussion 4-35
Benefits ''...., 4-35
Limitations 4-36
Efficiency 4-36
4.5 Summary 4-36
References 4-37
Section 5.0 Integration of Best Management Practices 5-1
Regrading and Revegetation 5-2
Daylighting 5-4
Coal Refuse Removal 5-4
Special Handling with Surface and Ground Water Controls 5-5
Miscellaneous BMP Combinations . 5-9
Summary 5-10
References 5-11
![
Section 6.0 Efficiencies of Best Management Practices 6-1
Limitations 6-3
6.1 Pennsylvania DEP - Remining Site Study 6-5
6.2 Observed Results 6-6
6.3 Predicted Efficiencies 6-26
6.3.1 Statistical Approach 6-26
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Coal Remining BMP Guidance Manual
6.3.2 Statistical Results 6-28
Individual BMPs 6-28
BMP Combinations 6-38
6.4 Discussion 6-59
6.4.1 Observed Results 6-59
Acidity Loading 6-60
Iron Loading 6-61
Manganese Loading 6-64
Aluminum Loading 6-65
Sulfate Loading 6-67
Flow Rate 6-68
6.4.2 Predicted Results 6-70
BMPs Implemented Alone 6-70
BMP Groups 6-74
Regrading and Revegetation , 6-75
Daylighting 6-78
Regrading, Revegetation, and Daylighting 6-80
Goal Refuse Removal 6-82
Overall Evaluation 6-84
Limitations 6-85
6.5 Summary 6-86
References 6-89
Section 7.0 Best Management Practices - Costs 7-1
Table Summary , 7-2
References 7-18
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Table of Contents
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Coal Remining BMP Guidance Manual
List of Tables
Introduction
Page
Table 1: Number of Stream Miles Impacted by AMD 3
Table 2: AML Inventory Totals of 4 Major AML Problem Types in Appalachia
and the U.S, as of September, 1998 6
Table 3: Coal Production by State (Short Tons) 8
Table 4: State by State Profile of Remining Operations 11
Table 5: Types of Remining Permits Issued by State 12
Table 6: Characteristics of Existing Remining Operations by State 13
Table 7: Potential Remining Operations by State 14
Table 8: Pennsylvania Remining Permits Which Required Treatment, June, 1997 17
Section 1.0 Hydrologic and Sediment Control Best Management Practices
Table l.l.Sa: Synopsis of Water Quality Data at Case Study 1 Site 1-23
Table l.l.Sb: Synopsis of Water Quality Data at Case Study 2 Site 1-24
Table 1.1.3c: Synopsis of Flow and Pollutant Loading at Case Study 3 Site 1-27
Table 1.3. la: Re vegetation Practices and Maintenance 1-77
Section 2.0 Geochemical Best Management Practices
Table 2.1a: Minimum Overburden Analysis Drill Hole Spacing Requirements, by State. 2-15
Table 2.1b: Number of Acres per Overburden Analysis Hole 2-17
Table 2.1c: Number of Acres per Overburden Analysis Hole Based on SOAP
Applications Received in 1993 2-17
Table 2.1d: Overburden Interval Sampling Requirements. 2-25
Table 2.1e: Compositing of Too Many 1-foot Intervals Can Underestimate Acid
Producing Potential 2-26
Table 2.2.1a: Distribution, Type and Amount of Alkaline Materials Used 2-34
Table 2.2.1b: Example Analyses of Coal Ash 2-35
Table 2.2.1c: Percentage of Sites Producing Net Alkaline Drainage by Net NP without
Thresholds 2-41
Table 2.2. Id: Percentage of Sites Producing Net Alkaline Drainage by Total NP without
Thresholds 2-41
Table 2.2.1e: Percentage of Sites Producing Net Alkaline Drainage by Net NP
with Thresholds 2-41
Table 2.2.1f: Percentage of Sites Producing Net Alkaline Drainage by Total NP
with Thresholds 2-42
Table 2.3.3a: Water Quality for Wells at the Case Study 2 Site 2-73
List of Tables
IX
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Coal Retaining BMP Guidance Manual
Table 2.4a: EPA Remitting Database (Appendix A), Special Handling of Toxic/Acid
Forming Materials ! 2-80
Table 2.4b: Saturated Thickness in Meters for Wells developed in Appalachian
Mine Spoil ". 2-89
Table 2.4.3a: Summary of Water Quality for Greene County Site Phases 1 and 2 2-118
Table 2.4.3b: Summary of Water Quality Conditions, Alkaline Redistribution Site 2-119
Section 3.0 Operational Best Management Practices
Table 3.1a: Summary of Overburden Analysis Data from a Surface Mine
Located in Logan County, West Virginia 3-8
Table 3.1b: Total Sulfur in Stratigraphic Sections Enclosing the Coal at a
Renaming Site in Westmoreland County, Pennsylvania. 3-10
Table 3.1c: Coal and Enclosing Strata Sulfur Values '. 3-20
Table 3.1d: Overburden Analysis from an Acid-producing Underground Mine in
Armstrong County, PA 3-21
Section 4.0 Passive Treatment
i !
1 I
Table 4.1: OLC Sizing Calculations 4-20
Table 4.3: Summary of Water Quality Data at Various Points Along a
Passive Treatment System 4-34
Section 5.0 Integration of Best Management Practices
Section 6.0 Efficiencies of Best Management Practices
Table 6.2a: Pennsylvania Remining Permits, Summary of Observed Water Quality
Results by Individual BMP 6-8
Table 6.2b: PA Remining Study: Observed Effects of BMP Groupings on Discharges. .. 6-17
Table 6.3a: PA Remining Study: Predicted Odds of Acidity Improvement or Elimination. 6-32
Table 6.3b: PA Remining Study: Predicted Odds of Iron Improvement or Elimination. .. 6-33
Table 6.3c: PA Remining Study: Predicted Odds of Manganese Improvement
or Elimination .t 6-34
Table 6.3d: PA Remining Study: Predicted Odds of Aluminum Improvement
or Elimination 6-35
Table 6.3e: PA Remining Study: Predicted Odds of Sulfate Improvement
or Elimination 6-36
Table 6.3f: PA Remining Study: Predicted Odds of Flow Improvement 6-37
Table 6.3g: Analysis of Discrete Groups based on Observed Acidity Results Using
Regrading and Revegetation as Reference Group 6-41
Table 6.3h: Analysis of Discrete Groups based on Observed Iron Results
Using Regrading and Revegetation as Reference Group.. 6-42
List of Tables
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Coal Remining BMP Guidance Manual
Table 6.3i: Analysis of Discrete Groups based on Observed Manganese Results
Using Daylighting as Reference Group 6-43
Table 6.3j: Analysis of Discrete Groups based on Observed Aluminum Results
Using Daylighting as Reference Group 6-44
Table 6.3k: Analysis of Discrete Groups based on Observed Sulfate Results
Using Daylighting as Reference Group 6-45
Table 6.31: Analysis of Discrete Groups based on Observed Flow Results
Using Daylighting as Reference Group 6-46
Table 6.3m: Analysis of Discrete Groups based on Observed Acidity Results Using
Daylighting as Reference Group. 6-47
Table 6.3n: Analysis of Discrete Groups based on Observed Iron Results Using
Daylighting as Reference Group 6-48
Table 6.3o: Analysis of Discrete Groups based on Observed Manganese Results
Using Daylighting as Reference Group 6-49
Table 6.3p: Analysis of Discrete Groups based on Observed Aluminum Results
Using Daylighting as Reference Group 6-50
Table 6.3q: Analysis of Discrete Groups based on Observed Sulfate Results
Using Daylighting as Reference Group 6-51
Table 6.3r: Analysis of Discrete Groups based on Observed Flow Results
Using Daylighting as Reference Group 6-52
Table 6.3s: Analysis of Discrete Groups based on Observed Acidity Results
Using Regrading, Revegetation, and Daylighting as Reference Group 6-53
Table 6.3t: Analysis of Discrete Groups based on Observed Iron Results
Using Regrading, Revegetation, and Daylighting as Reference Group 6-54
Table 6.3u: Analysis of Discrete Groups based on Observed Manganese Results
Using Regrading, Revegetation, and Daylighting as Reference Group 6-55
Table 6.3v: Analysis of Discrete Groups based on Observed Aluminum Results
Using Regrading, Revegetation, and Daylighting as Reference Group 6-56
Table 6.3w: Analysis of Discrete Groups based on Observed Sulfate Results
Using Regrading, Revegetation, and Daylighting as Reference Group 6-57
Table 6.3x: Analysis of Discrete Groups based on Observed Flow Results
Using Regrading, Revegetation, and Daylighting as Reference Group 6-58
Table 6.4a: Types of Mining and Minimal BMPs 6-74
Section 7.0 Unit Costs of Best Management Practices
Table 7a: Alkaline Addition 7-3
Table 7b: Anoxic Limestone Drains (ALDs) 7-4
Table 7c: Ash Fill Placement 7-5
Table 7d: Bactericides 7-6
Table 7e: Check Dams 7-7
Table 7f: Constructed Wetlands 7-8
Table 7g: Daylighting 7-9
Table 7h: Diversion Ditch 7-10
List of Tables xi
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Coal Returning BMP Guidance Manual
Table 7i: Diversion Wells, Alkalinity Producing 7-11
Table 7j: Drains, Pit Floor 7-12
Table 7k: Regrading of Abandoned Mine Spoil/Highwalls 7-13
Table 71: Revegetation 7-14
Table 7m: Sealing and Rerouting of Mine Water from Abandoned Workings 7-15
Table 7n: SiltFences 7-16
Table 7o: Special Handling for Toxic and Acid Forming Materials 7-17
List of Tables
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Coal Remining BMP Guidance Manual
List of Figures
Introduction
Page
Figure 1: Percentage of Total Number of Rahall Permits Issued by State 15
Figure 2: Status of 260 Pennsylvania Remining Permits 17
Figure 3: Percentage of Streams with a pH less than 6.0 for 24 Watersheds in the
Appalachian Basin 28
Figure 4: Percentage of Surface Water Sample Stations with Sulfate Greater than
75 mg/L for 24 Watersheds in the Appalachian Basin 29
Figure 5: Statigraphic Variation of Sulfur Content of 34-Coal Beds of the Cental
Appalachians 30
Figure 6: Example of Steep Topography and High Relief in Southern West
Virginia Showing Multiple Contour Strip Mines on Steep Slopes 32
Figure 7: Example of Moderate Slopes and Broader Valleys and Hilltops in
West-central Pennsylvania Showing Small Area Mines 33
Figure 8: Topographic Map Illustrating Contour Surface Mining 34
Figure 9: Topographic Map Illustrating Area Surface Mining 35
Section 1.0 Hydrologic and Sediment Control Best Management Practices
Figure l.l.la: Diagram of the Location of Surface Cracks Between Highwall
and Backfill 1-10
Figure l.l.lb: Schematic Diagram of a Cap Instilled on a Reclaimed Surface Mine.. 1-12
Figure 1.1.3a: Acidity Concentration at Discharge Point MD-12 Before and
After Remining 1-25
Figure 1.1.3b: Acidity Load at Discharge Point MD-12 Before and After Remining . 1-25
Figure 1.2a: Typical Correlation Between Discharge Flow and Pollutant Loading
in Mine Drainage Discharges 1-33
Figure 1.2.1a: Example of Mine Subsidence and Exposed Fractures 1-36
Figure 1.2.1b: Exposed Auger Holes 1-40
Figure 1.2.1c: Example of a Mine Entry Seal 1-41
Figure 1.2.1d: Example of a Virginia-Type Mine Entry Seal 1-42
Figure 1.2.1e: Example of a Mine Drain System 1-43
Figure 1.2.1f: Cross Section of an Example Chimney Drain ' 1-45
Figure 1.2.1g: Cross Section of Horizontal Highwall Drains 1-46
Figure 1.2.1h: Pit Floor Drain Patterns 1-48
Figure 1.2.1i: Pit Floor Drain 1-49
Figure 1.2.1J: Common Drilling Pattern for Pressure Grouting Wells 1-52
Figure 1.2.3a: Change in Flow Over Time (Case Study Discharge MP-1) 1-61
Figure 1.2.3b: Change in Flow Over Time (Case Study Discharge MP-4) 1-61
List of Figures
xui
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Coal Remitting BMP Guidance Manual
Figure 1.2.3c: Flow Rate Reduction, Pre- and Post-Remimng Periods (Case Study
Discharge MP-4) 1-62
Figure 1.2.3d: Flow Rate Reduction, Pre- and Post-Remining Periods (Case Study
Discharge MP-6) 1-63
Figure 1.3.1a: Example of aRock Check Dam 1-82
Figure 1.3.1b: Example of a Gabion Check Dam 1-83
Section 2.0 Geochemical Best Management Practices
Figure 2.2a: Solubility of Calcium Carbonate in Water at 25ฐC as a Function of
Partial Pressure of CO2 2-32
Figure 2.2.3a: Water Quality Before and After Mining at the Keating #2 Site,
Clinton, PA 1, 2-53
Figure 2.2.3b: Water Quality Before and After Mining at the Case Study 2 Site 2-54
Figure 2.2.3c: Water Quality at the Case Study 3 Site 2-56
Figure 2.3. la: Alkaline Recharge Channels and Capped Acid-producing
Material Pods 2-65
Figure 2.3.3a: Topography, Location of Recharge Trenches and Funnels, and
Locations of Seeps (Case Study 1, Upshur County, WV) 2-67
Figure 2.3.3b: Plot of Acidity versus Time for Seep #2 at Case Study 1 Mine 2-69
Figure 2.3.3c: Map of Case Study 2 Site 2-72
Figure 2.4a: Early Recommendation of the Pennsylvania Sanitary Water Board
for Handling Sulfuritic Material 2-85
Figure 2.4b: High and Dry Placement of Acidic Material 2-86
Figure 2.4.1a: Overburden Handling Procedures Depending on the Stratigraphic
Position of Acid-producing Materials 2-94
Figure 2.4.1b: Overburden Handling Procedures Depending on the Stratigraphic
Position of Acid-producing Materials 2-94
Figure 2.4.1c: Three-dimensional Conceptual View of High and Dry Placement
of Acid-forming Materials 2-97
Figure 2.4.1d: Projected Target Zone Determination for Placement of Acid
Forming Material within the Backfill 2-99
Figure 2.4.1e: Schematic of Special Handling of Acid-forming Materials by the
Submergence Technique 2-106
Figure 2.4.1f: Blending and Alkaline Redistribution Do Not Require the Isolation
of Acid-forming Materials in Isolated Pads 2-110
Figure 2.4.3a: Distribution of Sulfur and Neutralization Potential for Bedrock at
the Special Handling Site in Clarion County, PA. 2-112
Figure 2.4.3b: Distribution of Sulfur and Neutralization Potential for Spoil in the
Northern Hilltop where Bulldozers and Loaders Were Used 2-115
Figure 2.4.3c: Distribution of Sulfur and Neutralization Potential for Spoil in the
Southern Hilltop Where a Dragline was Used 2-116
Figure 2.5a: Rates of Pyrite Oxidation with and without Iron-oxidizing Bacteria . 2-128
Figure 2.5.3a: Effect of Anionic Detergents on Acid Production from Pyritic Coal. .2-132
xiv ; List of Figures
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Coal Remining BMP Guidance Manual
Figure 2.5.3b: Measured Profiles of Oxygen in Unsaturated Spoil 2-133
Figure 2.5.3c: Oxygen Cncentration with Depth in Coal Refuse in Pennsylvania
and Ohio 2-134
Figure 2.5.3d: Effect of Sodium Lauryl Sulfate on Runoff Water Quality at an 8-acre
Active Coal Refuse Pile in Northern West Virginia 2-136
Section 3.0 Operational Best Management Practices
Figure 3.1a: Relationship Between the Solubility of Calcium Carbonate and the
Partial Pressure of Carbon Dioxide at 25ฐC 3-6
Figure 3.1b: Advective Impacts on Unreclaimed Mine Spoil 3-6
Figure 3.1c: Potential Sources of Pit and Tipple Cleanings. 3-9
Section 4.0 Passive Treatment
Figure 4.1a: Anoxic Limestone Drain Construction 4-6
Figure 4.1b: Commonly Constructed Wetland Diagram 4-12
Figure 4.1c: Typical Wetland Cell Cross Section. 4-13
Figure 4.1d: Example of a Successive Alkalinity-Producing System Cell 4-16
Figure 4.1e: Typical Alkalinity-Producing Diversion Wells 4-25
Figure 4.1f: Example of Water Intake Portion of an Alkalinity-Producing
Diversion Well 4_26
Section 5.0 Integration of Best Management Practices
Figure 5.0a: Water Table Suppression in Conjunction with Special Handling of
Acidic Material 5-6
Figure 5.0b: Optimal Location for Special Handling of Acidic and Alkaline
Materials 5_8
Section 6.0 Efficiencies of Best Management Practices
Figure 6.4a: Impacts of BMP Combinations on Acidity Loading 6-61
Figure 6.4b: Impacts of BMP Combinations on Iron Loading 6-63
Figure 6 Ac: Impacts of BMP Combinations on Manganese Loading 6-65
Figure 6.4d: Impacts of BMP Combinations on Aluminum Loading 6-66
Figure 6.4e: Impacts of BMP Combinations on Sulfate Loading 6-68
Figure 6.4f: Impacts of BMP Combinations on Flow Rate 6-69
Section 7.0 Best Management Practices - Costs
List of Figures
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Glossary and Acronyms
Abiotic: Pertaining to the absence of plant and animal activity or mode of living.
Acid-Forming Materials (AFMs): Rocks (enclosing strata) and processed mine wastes that
have appreciable amounts of reactive sulfides. These sulfides are mainly iron disulfides in the
form of pyrite and marcasite, and will oxidize and subsequently combine with water to produce
acidity and yielding significant amounts of iron and sulfate ions.
Aerobic: A term used to describe organisms that only live in the presence of free oxygen. It is
also used to describe the activities of these organisms.
Alkaline addition: The practice of adding alkaline-yielding material into a mine site where the
overburden analysis indicates that there is a net deficiency of natural alkalinity. Alkaline material
used to perform this task is commonly limestone, various lime wastes, or alkaline CCW.
Anaerobic: A term used to describe organisms that live in the absence of free oxygen. It is also
used to describe the activities of these organisms.
Anoxic: An environment (gaseous or aqueous) with virtually no available free oxygen. Oxygen
required for chemical reactions or for organisms is severely limited. Little or no chemical and
biological activity that requires oxygen can occur. Water with less than 0.2 mg/L dissolved
oxygen may be considered anoxic.
Anoxic Limestone Drains (ALDs): Drains composed of limestone that are constructed and
covered to prevent the introduction of atmospheric oxygen to the system. Mine drainage is
diverted through these drains to increase the alkalinity and without the armoring of the limestone
by the iron in the water. The iron in the mine water must be in the ferrous state (Fe2+) and the
aluminum concentration must be relatively low in order for these systems to work properly over
the long term.
Anionic surfactants: Any of a number of cleansing detergents that act as bactericides, thus
inhibiting the presence of iron-oxidizing bacteria.
?
Anisotropic: A medium that exhibits different properties (e.g., hydraulic conductivity, porosity,
etc.) in each direction measurement.
Anticline: A generally convex upward fold in sedimentary rocks where the rock in the core of
the fold is older than those on the flanks. The opposite of a syncline.
Glossary and Acronyms
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Aquifer: A relatively permeable rock unit or stratigraphic sequence. Aquifers are saturated units
that are permeable enough to produce economic quantities of water at wells or springs.
Aquifer tests: A variety of hydraulic tests conducted with the use of a well to determine
porosity, permeability, and other properties of the rock unit tested. These tests usually involve the
addition or removal of a measured volume of water or a solid with respect to time, while the
response of the aquifer is measured in that well and/or other nearby wells.
Aquitard: Less permeable units in a stratigraphic sequence. These units are not impermeable,
but only permeable enough to be important on a regional ground-water system basis. Wells in
aquitards are not able to produce sufficient amounts of water for domestic or commercial use.
Auger mining: To extract coal from a highwall by drilling into the coal by the use of a
horizontal augering equipment. This is employed when removal of additional (thicker)
overburden is not economical.
Bactericide: Any of a number of materials that are used to kill bacteria, such as anionic
surfactants,
Baseline: Pre-mining environmental conditions, specifically, pre-mining pollutant loading in pre-
existing discharges. Baseline levels of pollutants can be used for comparison monitoring during
mining activity.
Bench: This term can be used in at least two distinct contexts in regards to mining. First it can
refer to a particular part of a coal seam split by a noncoal unit (e.g., shale, claystone), for example
a "lower bench". A second definition can refer to a land form where a nearly flat level area is
created along a slope with steeper areas above and below.
Bentonite: An encompassing term for variety or mixture of clays (primarily montmorillonite)
that swell in water. Bentonite is used commercially used as a sealant in wells and for creating low
permeability barriers.
Best Management Practice (BMP): Relative to remining, and as used in this document, BMPs
are mining or reclamation procedures, techniques, and practices that, if properly implemented,
will (1) cause a decrease in the pollution load by reducing the discharge rate and/or the pollutant
concentration, (2) reduce erosion and sedimentation control problems, and/or (3) result in
improved reclamation and revegetation of abandoned mine lands.
Biosolids: A general term for the residual solid fraction, primarily organic material, of processed
sewage sludge. A similar term is biosludge, which can be derived from other organic sources,
such as paper mill waste.
Biotic: Pertaining to plant and animal activity and mode of living.
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Bone coal: A relatively hard high-ash coal grading toward a carbonaceous shale, a high-organic
content shale.
Buffer: The ability of a solution to resist changes in pH with the addition of an acid or a base.
Calcareous shale: A shale with a significant calcium carbonate content. The calcium carbonate
content is sufficient to yield alkalinity with contact with ground water.
Carbonaceous: An organic-rich (carbon) rock, such as coal, "bone" coal, and organic-rich black
shale.
Cast-blasting: A method of directional overburden removal blasting.
Check dam: An above grade structure placed bank to bank across a channel/ditch (usually with
its central axis perpendicular to flow) for the purpose of controlling erosion. Check dams are
commonly composed of rip rap, earthen materials, or hay bales.
Chimney drain: A highly transmissive vertical drain composed of large rock fragments that will
intersect ground water coming in from, the highwall or the surface and rapidly directing this water
through and away from the main body of the mine spoil.
Claystone: A clay-rich rock exhibiting the some of the induration of shales, but without the thin
layering (laminations) or fissility (splits easily into thin layers).
Coal Combustion Wastes (CCW): The residual material remaining from the process of burning
coal for power generation and for other purposes. CCW includes fly ash, bottom ash, flue gas
desulfurization wastes, and other residues. CCW may also include the by-product of limestone
used for desulfurization during the combustion process.
Coal Refuse: The waste material cleaned from freshly-mined coal after it is excavated from the
pit or brought from underground. Coal refuse is commonly composed of carbonaceous shale,
claystone, bone coal, and minor to substantial amounts of "good" coal.
Confidence Interval: The range of values around a statistic (for example, the median) in which
the true population value of the statistic occurs with a given probability (often 95 percent).
Culm: Term used in the anthracite district of Pennsylvania when referring to coal refuse.
Daylighting: To surface mine through abandoned underground mine workings by the removal of
the overlying strata to access the remaining coal. Overburden removal exposes the remaining
coal pillars.
Glossary and Acronyms
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Diagenesis: The chemical, physical, and biologic actions (e.g., compaction, cementation,
crystallization, etc.) that alter sediments after deposition, exclusive of metamorphism and
surficial weathering.
Dragline: A large crane-like type of earth moving equipment that employs a heavy cable or line
to pull a excavating bucket through the material to be removed (overburden rock), thus filling it.
The bucket is then lifted, moved to away, and dumped.
Drawdown: The measured lowering of the water level in a well ( or aquifer) from the
withdrawal of water. It is reported as the difference between the initial water level and the level
during or after the withdrawal.
Diversion ditch: A ditch engineered and installed to collect surface water runoff and transport it
away from down gradient areas. These ditches are commonly installed to control runoff.
Evapotranspiration: The water loss from the land surface to the atmosphere caused by direct
evaporation and transpiration from plants.
. liquid,
Exsolve: The process by which where two materials, such as a gas and a liquid, unmix. For
example, when carbon dioxide (CO2) comes out of solution from water into the atmosphere.
Geotextiles: Any of a variety of manufactured materials (e.g., plastic sheeting) that are used to
prevent or impede the movement of ground water vertically or laterally or prevent erosion.
Ground-Water diversion well: A water well installed and designed to intercept and collect a
significant amount ground water, thus preventing the ground water from reaching an undesirable
area down gradient.
Grout curtain: A low or nearly impermeable barrier created in strata or fill by the use of
pressure grouting via a series of injection wells. In theory, the fractures arid other pore spaces are
filled with a low permeability grout thus impeding ground-water movement.
Highwall: The highest exposed vertical face of the coal and overburden of a surface mine at any
given time during mining. The final highwall is the maximum extent of surface mining.
i
Hummocky: Used to describe highly uneven topography, commonly composed of a series of
small irregularly-rounded hills or hummocks.
Hydraulic conductivity: The flow rate of ground water through a permeable medium. The flow
rate is given in distance over time (velocity), such as meters per second (m/s).
Hydrologic: Pertaining to ground and/or surface water systems.
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Hydrologic unit: A term used to describe an area where infiltrating waters will drain to a point
or a series of related points. The area is hydrologically distinct and isolated from adjacent
hydrologic units,
Hydrolyze: Chemical reactions involving water, where H"1" or OH" ions are consumed in the
process.
Hydrothermal: Chemical and physical activity pertaining to hot ground water associated with
underlying igneous activity.
/
Induced Alkaline Recharge: Systems installed in surface mines to introduce recharge of
alkaline charged waters to treat or abate the production of acid mine drainage. Surface water is
diverted to where it contacts trenches or "funnels" filled or lined with alkaline rocks (e.g.,
limestone). These trenches are closed systems that induce this water to infiltrate and recharge the
spoil.
Infiltration: The downward flow of water into the land surface through the soil or lateral
ground-water flow from one area to another.
Interaction: The effect of a variable (for example, the presence or absence of a BMP) on a
variable of interest (for example, the change in a discharge) is significantly effected by a third
variable (for example, the presence or absence of another BMP).
Interfluves: Regions of higher land lying between two streams that are in the same drainage
system.
Logistic Regression Model: A statistical method of evaluating the relationship between one or
more variables on a variable with a discrete (countable) number of outcomes.
Lowwall: A exposed vertical face of the coal and overburden generally representing the lowest
cover to be encountered. Common to mines where the coal is not mined completely out to the
coal outcrop and frequently spatially opposite to the location of the highwall.
Metamorphic: The mineralogical, chemical, and structural alteration of buried sediments and
rock from heat and pressure.
Mine spoil: Overburden strata (rock) broken up during the course of surface mining and replaced
once the coal is removed. Particle sizes in the backfill (spoil) range from clay-size to those
exceeding very large boulders.
Odds: The probability of an event occurring divided by the probability of an event not occurring.
Glossary and Acronyms
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Odds ratio: The odds of an event occurring divided by the odds of a second event occurring,
used to compare how likely two different events are.
Oxic: An environment (gaseous or aqueous) with readily available free oxygen (oxygen not
limited for typical chemical reactions or for organisms that require it).
Oxic Limestone Drains: These are limestone drains that are partially open to the atmosphere.
These drains induce elevated CO2 concentrations to build up, which in turn causes an aggressive
limestone dissolution and alkalinity production, thus preventing armoring from the iron in the
water.
Open Limestone Channels: These are limestone drains that are open to tne atmosphere. Some
research has indicated that even armored with iron these drains may impart 20 percent of the
alkalinity that unarmored limestone will yield.
Outcrop: The exposure where a specific rock unit intersects the earths surface. The outcrop can
be covered with a thin layer of surficial material such as colluvium.
'!
; ' I
Parting: A noncoal unit that commonly separates parts (benches) of a coal seam. Parting rock
commonly consists of shale, claystone, or bone coal. Sometimes called a binder.
Passive treatment: Methods of mine drainage treatment requiring minimal maintenance after the
initial installation. Passive treatment systems include but are not limited to aerobic and anaerobic
wetlands, successive alkaline producing systems, and anoxic limestone drains. -
Permeability: The ability of a rock or sediment to transmit a fluid (e.g., water). It is directly
related to interconnectedness of the void spaces and the aperture widths.
Pillar: A solid block of coal remaining after conventional underground mining (room and pillar)
mining has occurred.
Piping: The action of substantial volumes of ground water transporting fine-grained sediments
through unconsolidated materials, such as mine spoil, leaving large conduits or voids in the
process.
Pit Cleanings: Noncoal material (e.g., seat rock, roof rock or parting material) separated from
the saleable coal at the mine pit. This material commonly contains elevated sulfur values and is
usually potentially acid producing.
i
Pit floor drains: As the name implies, these are drains that are installed in or along the pit floor
to collect and rapidly transmit ground water through and away from the spoil. They are
commonly constructed of perforated drain pipe covered in limestone or sandstone gravel.
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Pore gas: Gases located and stored in the interstitial or pore spaces in soil, spoil, or other earthen
materials above the water table.
Porosity: The ratio of open or void space volume compared to the total volume of rock or
sediment. Commonly given in units of percent.
Pozzolonic: A property of a material to be, to some degree, self-cementing.
Pre-existing discharge: Pollutional discharge resulting from mining activities prior to August 3,
1977 and not physically encountered during active mining operations. Under the Rahall
Amendment to the Clean Water Act, a pre-existing discharge is defined as any discharge existing
at the time of permit application.
Probability: On a scale of 0-100, how frequently a given event (for example, a discharge
improving) would occur.
Pyrolusiteฎ systems: A large open limestone bed that mine water is allowed to slowly pass
through. The system is inoculated with "specially developed bacteria" to promote the formation
pyrolusite (an manganese oxide), thus removing manganese from solution. More recent research
indicates that the mineral formed is todorokite (a hydrated manganese, calcium, magnesium
oxide) and the bacteria that aid this mineral formation most likely exist within the. system
naturally without inoculation.
Reminmg: Surface mining of abandoned surface and/or underground mines for-which there were
no surface coal mining operations subject to the standards of the Surface Mining Control and
Reclamation Act. Remining operations implement pollution prevention techniques while
extracting coal that was previously unrecoverable.
Rill: Small erosional gully or channel created by runoff.
Rip rap: Materials (rock, cobbles, boulders, straw) placed on a stream bank, ditch or filter as
protection against erosion.
Rivulet: A small stream or streamlet that develops from rills, commonly located on steep slopes.
Sample Median: In a set of numbers, the value where the number of results above and below the
value are equal.
Scarification: The act of making a series of shallow incisions into the pit floor, topsoil, or other
surface to loosen or break up the material to foster beneficial actions, such as exposure of
alkaline material or promote plant growth.
Seep: A low-flowing surface discharge point for ground water. A low-flow spring.
Glossary and Acronyms
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Shoot and shove mining: A pre-SMCRA mining method that involved shooting or blasting the
overburden and pushing (shoving) it down the hillside. This type of operation was most common
in steeply-sloped regions, and resulted in abandoned highwalls, exposed pit surfaces, and
steep abandoned spoil piles below the mine.
Shotcrete: A mixure of portland cement, water, and sand that can be pumped under pressure
applied (sprayed) via a hose. It is commonly used for sealing in underground mines and for
surface features, such as streams. Also called gunite.
Special handling: A process where potentially acidic or alkaline material is segregated
(stockpiled) during surface mining and selectively placed during reclamation in -lifts or pods the
backfill with respect to the projected post-mining water table and/or the final ground surface.
Spoil swell: The increase in volume exhibited by mine spoil over the original volume the
material prior to mining. Swell values can approach 25 percent in some regions.
Stemming: Inert material placed in blast holes above and between the explosive material to
confine the energy of the explosion and maximize the breaking of the rock.
!| !
Stoichiometric: Used to describe the proportions of elements that combine during, or are yielded
by, a chemical reaction.
Stress-relief fractures: Fractures in rock which form at relatively shallow depths caused by
relaxation from the removal of the overlying rock mass from erosion. The retreat of glaciers in
the northern Appalachian Plateau also may have aided the formation of these fractures. They are
most common at depths of 200 feet or less.
i ,,, 'i ' i
Subaerial: Used to describe processes or resulting conditions from exposure to the atmosphere
at or near the lands surface.
Suboxic: An environment (gaseous or aqueous) with very low concentrations of free oxygen.
The levels are not low enough to be considered anoxic, but are suppressed to the degree that
chemical and biological activity are controlled and attenuated.
Successive Alkaline Producing System (SAPS): A series of passive treatment systems that
mine water is passed through by which alkalinity is imparted from sulfate reduction and
limestone dissolution.
Syncline: A generally concave upward fold in sedimentary rocks where the rocks in the core of
the fold are younger. The opposite of a anticline.
Tipple refuse (cleanings): The waste material left after raw coal is run through a "cleaning
plant". It usually has an elevated sulfur content.
i
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Turbulent flow: Flow characterized by irregular, tortuous, and heterogeneous flow paths.
Vadose zone: Zone of aeration above the water table, unsaturated zone.
Water year: According to the United States Geological Survey (USGS) a water year occurs
between October 1 and September 30.
Acronyms and Abbreviations
ABA: acid-base accounting
AFM: acid-forming material
ALD: anoxic limestone drains
AMD: acid mine drainage
AML: abandoned mine land
AMLIS: Abandoned Mine Land Inventory System
AOC: approximate original contour
ASTM: American Society for Testing and Materials
BAT: Best Available Technology Economically Achievable
BMP: Best Management Practice
BPJ: Best Professional Judgement
BPT: Best Practicable Control Technology
C: centigrade
CCW: coal combustion wastes
CFR: Code of Federal Regulations
cfs: cubic feet per second
CWA: Clean Water Act
cm: centimeter(s)
DO: dissolved oxygen
DOE: Department of Energy
ENR: Engineering News Record
EPA: Environmental Protection Agency
EPRI: Electric Power Research Institute
FIFRA: Federal Insecticide, Fungicide and Rodenticide Act
fps: feet per second
FRP: Federal Reclamation Program
gdm: grams per day per meter squared
GIS: Geographic Information System
gpm: gallons per minute
IMCC: Interstate Mining Compact Commission
L/min: liters per minute
Ibs/day: pounds per day
Glossary and Acronyms
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Ibs/ft3: pounds per cubic feet
mg/L: milligrams per liter
MPA: maximum potential acidity
m/s: meters per second
mt: metric tonnes
NNP: net neutralization potential
NP: neutralization potential
NPDES: National Pollutant Discharge Elimination System
NSPS: New Source Performance Standards
OBA: overburden analysis
OLD: oxic limestone drain
OLC: open limestone channel
OSMRE: Office of Surface Mining and Reclamation Enforcement
PA DEP: Pennsylvania Department of Environmental Protection
ppt: parts per thousand
psi: pounds per square inch
PVC: polyvinyl chloride
RAMP: Rural Abandoned Mine Program
RUSLE: Revised Universal Soil Loss Equation
SAPS: successive alkalinity-producing systems
SLS: sodium lauryl sulfate
SMCRA: Surface Mining Control and Reclamation Act
SOAP: Small Operator Assistance Program
SOS: Standard of Success
TCLP: Toxicity Characteristic Leaching Procedure
TMAT: Total Mined Area Triangle
TSS: total suspended solids
TVA: Tennessee Valley Authority
USBM: United States Bureau of Mines
USDA: United States Department of Agriculture
USGS: United States Geological Survey
USLE: Universal Soil Loss Equation
WPA: Works Progress Administration
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Executive Summary
Purpose
This manual was created to support EPA's proposal of a Retaining subcategory under existing
regulations for the Coal Mining industry. The purpose of this guidance manual is to assist
operators in the development and implementation of a best management practice (BMP) plan
specifically designed for a particular remining operation. This guidance manual also was
developed to give direction to individuals reviewing remining applications and associated BMP
plans. This document is not intended as a substitute for thoughtful and thorough planning and
decision making based on site-specific information and common sense.
Organization
This manual is organized to function as a user's guide to meet remining plan requirements and to
improve abandoned mine land conditions during remining operations. The manual is divided into
the following sections:
Introduction - presenting state-specific abandoned mine land conditions, industry profile
information, the status of remining operations, and general information regarding
remining BMPs; the scope of pre-Surface Mining Control and Reclamation Act
(SMCRA) mining and associated acid mine drainage contamination
Sections 1.0 through 5.0 - describing hydrologic, sediment and geochemical control BMP
implementation practices, site assessment required to determine implementation of these
practices, implementation guidelines, design considerations, and case studies;
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Section 6.0 - detailing the efficiency of reminding BMPs in regards to the water quality of
pre-existing discharges;
:[ I
Section 7.0 - providing BMP implementation unit cost information;
Appendix A - presenting EPA Coal Remining Database and including summary data and
information from 61 state remining and abandoned mine land (AML) project data
packages;
Appendix B - presenting summary data from the Pennsylvania Remining Study of 112
closed remining operations affecting 248 pre-existing discharges; and
Appendix C - presenting responses to the Interstate Mining Compact Commission
(IMCC) remining solicitation sheet from 20 member states.
Details of the contents of each section are provided in the Section Outline.
il i
Limitations
This manual provides information on many hydrologic and geochemical control BMPs which can
be used to prevent or reduce pollution loading from abandoned mine lands during remining
operations. This manual describes the best management practices and controls, provides guidance
i
on how, when, and where to use them, and recommends maintenance procedures. However, the
I
effectiveness of these controls lies fully in the hands of those individuals responsible for site
operations. Although specific recommendations are offered in the following chapters, careful
consideration must be given to selecting the most appropriate control measures based on site-
" " I
specific features and conditions, and on properly installing the controls in a timely manner.
Finally, although this manual provides guidelines for maintenance, it is up to the responsible
I
party to make sure controls are carefully maintained or they will prove to be ineffective.
This manual is not intended as a stand-alone document in terms of BMP plan development and
implementation. Additional information sources pertaining to remining and various aspects of
i
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Coal Remining BMP Guidance Manual
BMPs can and should be consulted. Many of these information sources are referenced throughout
this guidance manual. This manual is intended for use by individuals with the background or
experience to adequately understand the technical aspects detailed herein. Those individuals
charged with developing, reviewing, implementing, and enforcing remining BMP plans, must be
knowledgeable of all aspects of remining operations (e.g., hydrology, geochemistry, mining
operations, etc.), and must be able to modify them when appropriate.
Results Summary
Review of existing data and information that was used to prepare this document indicates that
remining operations accompanied by proper implementation of appropriate BMPs is highly
successful in reducing the pollution load of mine drainage discharges. The information also
shows that remining BMPs typically are used in combination as part of an overall and site-
specific BMP plan. Critical to the effectiveness of a BMP plan in terms of water quality and
AML improvement is that the plan is well designed and engineered, implemented as proposed,
and that the implementation and subsequent post-mining results are verifiable. -
Executive Summary
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Introduction
Environmental Conditions
Acid drainage from abandoned underground and surface coal mines and coal refuse piles is the
most chronic industrial pollution problem in the Appalachian Coal Region of the Eastern United
States. It has been estimated that there are currently over 1.1 million acres of abandoned coal
mine lands, over 9,709 miles of streams polluted by acid mine drainage (AMD), 18,000 miles of
abandoned highwalls, 16,326 acres of dangerous spoil piles and embankments, and 874
dangerous impoundments (IMCC, 1998; Lineberry and others, 1990; OSMRE, 1998). Prior to
the passage of the federal Surface Mining Control and Reclamation Act (SMCRA) of 1977
reclamation of mining sites was not a federal requirement and therefore, often was not done.
However, some states did have reclamation requirements prior to 1977. Of the land disturbed by
coal mining between 1930 and 1971, roughly only 30 percent has been reclaimed (Lineberry and
others, 1990).
One of SMCRA's goals was to promote the reclamation of mined areas left without adequate
reclamation prior to the enactment of SMCRA and which continue, in their unreclaimed
condition, to substantially degrade the quality of the environment, prevent or damage the
beneficial use of land or water resources, or endanger the health or safety of the public.
Waters Impacted by Pre-SMCRA Mining
Problematic mine drainage forms when air and water come into contact with certain minerals in
rocks associated with mining. Pyrite and other sulfide minerals in rocks associated with coal
react with oxygen and water to form acid and yield dissolved metals (such as aluminum, iron,
and manganese). The acidity and dissolved metals then contaminate surface and ground water.
The production of acid mine drainage can occur during several phases of the mining process, and
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Coal Remining BMP Guidance Manual
can continue well after the mine has closed. In Great Britain, for example, Roman mine sites
dating back 2,000 years continue to generate acid mine drainage today (USGS, 1998).
Streams that are impacted by acid mine drainage characteristically have low pH levels (less than
6.0, standard units) and contain high concentrations of sulfate, acidity, dissolved iron, and other
metals. These conditions commonly will not support fish or other aquatic life. Even if the acid
was neutralized (pH raised), the metals will precipitate and coat the stream bed, making it
unsuitable for supporting aquatic life. Additionally, the impact of mine drainage on the
waterway aesthetics results in undesirable conditions for visitors and recreational users (EPA
Region m and OSM, 1997).
Acid mine drainage can result from both surface and underground coal mining and from coal
refuse piles. In surface mining, the rock overlying the coal (overburden) is excavated, and in the
process, broken into a range of large to small rock fragments which are replaced in the pit after
the coal is removed. This exposes the acid-forming minerals in some rocks to air and water
resulting in a high probability of AMD formation, if such minerals are present in sufficient
i
quantities. In underground mining, large reservoirs of AMD may form in the cavern-like
passageways below the earth surface. These reservoirs are constantly replenished by ground-
water movement through the mineral-bearing rocks, creating more AMD. Water from these
"mine pools" seeps through the hillsides or flows freely from abandoned mine entries, enters
, I
streams, and deposits metal-rich precipitates on the substrate downstream. Coal refuse piles
often contain excessive amounts of pyritic materials and water flowing through the piles can
become highly acidic.
i
Mine drainage discharges can be as small as an unmeasurable flow, or they may be huge torrents
of thousands of gallons per minute. Receiving streams frequently do not contain sufficient
alkalinity to neutralize the additional acid, thus its water quality may be adversely impacted and
the stream's uses impaired. Even if the stream has sufficient alkalinity to improve pH,
precipitation of iron, manganese, and/or aluminum may occur.
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Ninety percent of AMD comes from abandoned coal mines (mostly underground mines) where
no individual or company is responsible for treating the water (Skousen and others, 1999). Acid
mine drainage impacts approximately 9,709 stream miles (IMCC, 1998). Table 1 provides a
breakdown by state of the 9,709 stream miles estimated to be impacted by AMD.
303(d) List
Pursuant to Section 303 (d) of the Clean Water Act, States biannually submit a list of water
bodies not presently supporting designated uses to the U.S. Environmental Protection Agency
(EPA). As required by 40 CFR 130, 7(b)(4), States biannually compile a 303(d) list of streams
affected by such pollution sources as acid mine drainage. Priority and non-priority stream lists
are generated on the basis of analytical and benthic investigations. Table 1 contains a summary
of the stream miles affected by AMD according to the 1998 303(d) lists for each state.
Table 1: Number of Stream Miles Impacted by AMD
State
Alabama
Illinois
Indiana
Kentucky
Maryland
Missouri
Ohio
Pennsylvania
Tennessee
Virginia
West Virginia
Totals
Stream Miles
(Source A)
65
NA
0
600
430
139
1,500
3,000
1,750
NA
2,225
>9,709
Stream Miles
(Source B)
152
607
3,239
17
1,100
>5,115
Stream Miles
(Source- C)*
50+440 acres
__
141+219 acres
2,149
726+ 5 10 acres
44
2,019
>5,129 + 1,169 acres
* May include area of affected lakes and reservoirs
Source A: IMCC, 1998
Source B: Faulkner & Skousen, 1998
Source C: State 303(d) lists, 1998.
NA = Not Available
Introduction
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Coal Remining BMP Guidance Manual
Abandoned Mine Land Program andAMLIS
Title IV of SMCRA established the Abandoned Mine Land (AML) program which provides for
the restoration of eligible lands and waters mined and abandoned or left inadequately restored.
The AML program stipulates that a tax of $0.35 per ton of surface mined coal, $0.15 per ton for
underground mined coal, and $0.10 for lignite coal is paid into the AML fund. These funds are
deposited in an interest bearing Abandoned Mine Reclamation Fund which is used to pay
reclamation costs of AML projects. When Congress passed SMCRA, it realized that AML fees
would not generate enough revenue to address every eligible site, and left the States and Indian
Tribes the choice of which projects to select for funding.
Expenditures from the AML fund are authorized through the regular congressional budgetary and
appropriations process. SMCRA specifies that 50 percent of the reclamation fees collected in
!
each state be allocated to that State for use in its reclamation program. SMCRA further specifies
that 50 percent of the reclamation fees collected annually with respect to Indian lands be
allocated to the Indian tribe having jurisdiction over such lands, subject to the Indian tribe having
eligible abandoned mine lands and an approved reclamation plan. The remaining 50 percent is
used by the Office of Surface Mining Reclamation Enforcement (OSMRE) to fund emergency
j I
projects and high-priority projects in states and Indian tribes without approved AML programs
under the Federal Reclamation Program (FRP); to fund the Rural Abandoned Mine Program
(RAMP); to fund the Small Operator Assistance Program (SOAP); to supplement the State-share
funding for reclamation of abandoned mine problems through State/Indian tribe reclamation
programs; and for Federal expenses to collect the AML fee and administer the AML program.
The Office of Surface Mining's Abandoned Mine Land Inventory System (AMLIS) catalogs
AML areas by problem type and estimated reclamation cost. The most serious problems are
those posing a threat to health, safety, and general welfare of people (Priority 1 and Priority 2, or
"high priority"). These are the only problems which the law requires to be inventoried. The 17
Priority 1 and 2 types are:
4 Introduction
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Coal Remining BMP Guidance Manual
Clogged Streams
Dangerous Highwalls
Dangerous Piles & Embankments
Gases: Hazardous/Explosive
Hazardous Water Bodies
Portals
Polluted Water: Human Consump.
Surface Burning
Clogged Stream Lands
Dangerous Impoundments
Dangerous Slides
Hazard. Equip. & Facilities
Ind./Residential Waste
Polluted Water: Agri. & Ind.
Subsidence
Underground Mine Fires
Vertical Openings
AML problems impacting the environment are known as Priority 3 problems. While SMCRA
does not require OSMRE to inventory every unreclaimed Priority 3 problem, some states and
Indian Tribes have chosen to submit such information. There are twelve Priority 3 problem types
in AMLIS and they are:
Benches Industrial/Residential Waste
Equipment/Facilities Gob
Highwalls Haul Road
Mine Openings Slump
Pits Spoil Areas
Slurry Other
Of the $3.6 billion of high priority (Priority 1 and 2) coal related AML problems in the AML
inventory, $2.5 billion, or 69 percent, have yet to be funded and reclaimed. Priority 1 and 2
AML problems are those that pose a significant health and safety problem, and does not include
environmental problems such as AMD. Current estimates indicate that ninety percent of the $1.7
billion coal related environmental problems (Priority 3) in the AML inventory are not funded and
reclaimed (OSMRE, 1999). An important note is that the AMLIS Priority 3 inventory represents
only a small part of the total environmental problem as states are not required to inventory
Priority 3 problems in general. In addition, the AML inventory is more complete for some states
than for others, and the frequency of occurrence of different types of problems varies widely
Introduction
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Coal Remining BMP Guidance Manual
between states. Table 2 lists inventories of abandoned mine land conditions in nine Eastern Coal
Region states.
Table 2: AML Inventory Totals of 4 Major AML Problem Types in
the U.S., as of September, 1998 (OSMRE, 1998)
State
Alabama
Indiana
Kentucky
Maryland
Ohio
Pennsylvania
Tennessee
Virginia
West Virginia
Appalachia Total
% of U.S. Total
U.S. Total
Clogged Stream
Lands
(acres)
0
0
7,936
5
11,850
570
0
1,717
164
22,242
93%
24.028
Dangerous
Highwalls
(linear feet)
177,945
1,650
64,718
8,250
56,453
1,116,071
36,560
91,889
1?358.,616
2,912,152
68%
4.252,115
Dangerous Piles
or Embankments
(acres)
2,209
25
1,137
156
29
5,294
779
. 154
1,928
11,711
72%
16.282
Appalachia and
Dangerous slides
(acres)
21
0
1,519
8
99
7
92
117
346
2,209
98%
.2.253
The cost of remediating AML problems far exceed the amounts that may ever be collected,
hence, alternative solutions should be found to reclaim remaining AML sites. AML funds fall
far short for may states, especially for those that were extensively mined prior to SMCRA. For
example, in Virginia, an estimated $432 million in Priority 1, 2, and 3 AML liabilities remain
while annual funding in recent years has been on the order of $ 5 million (Zipper and Lambert,
1998). At current rates, it will take better than eighty years to reclaim Virginia's abandoned
mine land problems.
Remining can be one of the tools used to help the AML funding shortfall. A report by Skousen
and others (1997) compared the cost of remining ten sites in Pennsylvania and West Virginia
with the costs of reclamation to AML standards. All ten remining operations resulted in
Introduction
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Coal Remining BMP Guidance Manual
environmental benefits. In all but two cases, the coal mined and sold from the remining
operation produced a net profit for the remining company. Remining of these ten sites saved the
AML program over $4 million (Skousen and others, 1997).
Industry Profile
The U.S. coal mining industry has its commercial roots back to approximately 1750 when coal
was first mined from the James River coalfield near Richmond Virginia. More recently, U.S.
coal production set record levels in 1997, when a record 1.09 billion short tons were mined. The
electric power industry used a record 922 million short tons (85 percent of coal mined) that year.
The three highest ranking coal producing states in 1997 were Wyoming (26 percent), West
Virginia (16 percent), and Kentucky (14 percent), which together accounted for 56 percent of the
coal produced in the United States (DOE, 1997).
The most recent estimates available on coal production by state in the U.S. are summarized in
Table 3. In 1996, the Energy Information Administration estimated that the United States has
enough coal to last 250 years (USGS, 1996). They estimated the demonstrated reserve base of
coal in the United States was 474 billion short tons. Although recoverability rates differ from
site to site, an estimated 56 percent (or 265 billion tons) of the demonstrated reserve base is
presently recoverable (DOE, 1999).
Regulatory History
On October 13, 1982, EPA promulgated final effluent guidelines under the Clean Water Act to
limit the discharges from the coal mining industry point source category. The rale amended
previously promulgated effluent limitations guidelines based on "best practicable control
technology currently available" (BPT) and "new source performance standards" (NSPS), and
established new guidelines based on "best available technology economically achievable" (BAT).
Introduction
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Coal Reminine BMP Guidance Manual
Table 3: Coal Production by State (Short Tons) (DOE, 1997)
State
Alabama
Alaska
Arizona
Arkansas
Colorado
Illinois
Indiana
Kansas
Kentucky
Louisiana
Maryland
Missouri
Montana
New Mexico
North Dakota
Ohio
Oklahoma
Pennsylvania
Anthracite
Bituminous
Tennessee
Texas
Utah
Virginia
Washington
West Virginia
Wyoming
Appalachian Total
Interior Total
Western Total
East of Miss. River
West of Miss.
U-S. Total
S
Underground
18,505,000
-
-
-
17,820,000
34,824,000
3,530,000
-
96,302,000
3,301,000
_.
8,000
-
-
16,949,000
212,000
419,000
54,410,000
1,396,000
-
26,683,000
26,929,000
-
116,523,000
2,846,000
308,360,000
64,941,000
47,357,000
373,089,000
47,569,000
420.657.000
Surface
5,963,000
1,450,000
11,723,000
18,000
9,628,000
6,334,000
31,967,000
360,000
59,551,000
3,545,000
859,000
401,000
40,997,000
27,025,000
29,580,000
12,205,000
1,409,000
4,259,000
17,110,000
1,904,000
53,328,000
-
8,907,000
4,495,000
57,220,000
279,035,000
159,418,000
105,923,000
403,934,000
206,281,000
462,994,000
fifi9.274.rtOO
Total
24,468,000
1,450,000
11,723,000
18,000
27,449,000
41,159,000
35,497,000
360,000
155,853,000
3,545,000
4,160,000 '
il
401,000
41,005,000
27,025,000
29,580,000
29,154,000
1,621,000
-
4,678,000
1
71,520,000
3,300,000
i
53,328,000
26,683,000
35,837,000
4,495,000
173,743,000
281,881,000
467,778,000
170,863,000
451,291,000
579,369,000
510,563,000
1.089.932.000
<
Mines
51
1
2
3
14
28
39
3
529
2
18
4
8
6
6
81
11
131
272
27
12
12
191
3
349
25
1,602
149
77
1,716
112
1,828
Introduction
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Coal Reminins BMP Guidance Manual
The October 1982 rule established four subcategories for promulgation of effluent limitations
based on BAT: (1) preparation plants and associated areas; (2) acid mine drainage; (3) alkaline
mine drainage; and (4) post-mining discharges. The limitations of acid mine drainage, post-
mining discharges at underground mines, and coal preparation plants and associated areas were
based on neutralization and settling technologies. The limits for alkaline mine drainage were
based solely on settling technology. For the coal mining category, BAT and BPT effluent limits
were identical.
The issue of remining was raised during the comment period following the 1982 proposal of the
final rule. Comments addressed the fact that technology-based standards would likely serve as a
deterrent to remining activities, since the operator would have to assume responsibility for
treating effluent from previous operations that already may be significantly contaminated.
However, the question of the appropriate effluent limitations for remining operations was not a
subject of the proposal, and was therefore not addressed in detail in the final rule. Instead, EPA
stated that generally, effluent limitations guidelines and standards are applicable to point source
discharges even if those discharges pre-dated the remining operation.
In 1987, the Clean Water Act (CWA) was amended to provide incentives for remining
abandoned mine lands that were mined prior to the 1977 passage of the Surface Mining Control
and Reclamation Act (SMCRA). The modification of the CWA (known as the Rahall
Amendment) established that BAT effluent limitations for iron, manganese, and pH are not
required for discharge conditions existing prior to remining activities.
Remining
Development of modern surface-mining techniques has allowed for more efficient and effective
removal of coal deposits; consequently, mining is now feasible in areas where mining was
previously uneconomical. A report prepared for the U.S. Department of Energy estimates that
Introduction
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Coal Remining BMP Guidance Manual
460 million to 1.1 billion tons of coal could potentially be recovered from remining in mine
states (PA, WV, MD, VA, KY, TN, OH, IN, TL) (Veil, 1993).
In 1987 Congress passed the "Rahall Amendment" to the Clean Water Act. The CWA was
amended to include section 301(p) in order to provide remining incentives for permits containing
abandoned mine lands that pre-date the passage of SMCRA in 1977. The Rahall Amendment
established that BAT effluent limits for iron, manganese, and pH (40 CFR part 434) are not
required for pre-existing mine drainage discharges. Instead, site-specific BAT limits determined
by Best Professional Judgement (BPJ) are applicable to these pre-existing discharges, and the
permit effluent limits for iron, manganese, and pH (or acidity) may not exceed pre-existing
i
"baseline" levels. The Rahall Amendment established new effluent guidelines for pre-existing
discharges for remining operations potentially freeing the operators from the requirement to treat
degraded pre-existing discharges to the statutory BAT levels.
"Remining," as defined hi the 1987 Rahall Amendment and this document refers to " a coal
ii ,
mining operation which began after the enactment of the Rahall Amendment at a site on which
coal mining was conducted before the effective date of the Surface Mining Control and
Reclamation Act of 1977.
!
On September 3, 1998, the Interstate Mining Compact Commission (EVICC) distributed a
Solicitation Sheet to member states in support of continuing efforts to collect data and
information required for proposal of a remining subcategory under 40 CFR 434. The solicitation
sheet was intended to gather information necessary to assess current industry remining activity
and potential. The results of the solicitation are summarized in numerous tables in this report.
IMCC member states have estimated that there are currently 150 mining companies in ten states
j
j
actively involved in remining activities. These companies are producing at least 25.1 million
tons of coal annually; and employing approximately 3,000 people (Table 4).
10
Introduction
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Coal Remining BMP Guidance Manual
Table 4: State by State Profile of Remining Operations (IMCC, 1998)
Alabama
Alaska
Colorado
Illinois
Indiana
Kentucky
Maryland
Missouri
Mississippi
Montana
New Mexico
Ohio
Pennsylvania
Tennessee
Texas
Utah
Virginia
West
Wyoming
Totals
Number of
mining
companies
with remining
permits
20
0
0
35
2
4
13
2
0
0
0
3
50
10
0
0
3
8
0
150
Total employment
at remining
operations
(Number of
employees)
ND
0
0
70
NA
ND
150
0
0
0
ND
2,345
75 - 100
0
0
300
ND
0
>2.940-2r965
Annual coal
production from
remining sites
(tons)
ND
0
0
200,000
720,000
ND
650,000
0
0
~
0
ND
17,530,000
3,000,000
0
0
3,000,000+
ND
0
>25.1 00.000
Estimated coal
reserves
(tons)
ND
0
ND
10,000,000
NA
ND
ND
ND
ND
0
ND
- 100,000,000+
50,000,000
0
ND
ND
ND
ND
>160.000rOOO
NA = Not Available; = No Response; ND = No Data.
Currently there are approximately 1,072 active remining permits and 638 AML projects,
(Table 5). Of these 1,072 permits, 330 (31 percent) are Rahall type permits where the effluent
standards for pH, iron, and manganese have been relaxed.
Introduction
11
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Coal Remining BMP Guidance Manual
Table 5: Types of Remining Permits Issued by State (IMCC, 1998)
State
Number of
Rahall Permits
Number of Non-
Rahall Permits
(a)
"Other"
Remining
Permits/Projects
(b)
Remining
Permits (% of
Total)
Alabama
Alaska
Colorado
Illinois
Indiana
Kentucky
Maryland
Missouri
Mississippi
Montana
North Dakota
New Mexico
Ohio
Pennsylvania
Tennessee
Texas
Utah
Virginia
West Virginia
Wyoming
Totals
10
0
0
0
0
4
2
0
0
0
0
0
3
300
0
0
0
3
8
330
61
0
0
41
1
N/A
21
20
0
0
ND
40
350-450
0
0
158
692-792
1
0
15
0
1
1
0
0
i
0
14
!
--
101
3
0
0
0
501
1
638
ND
0
0
0
1
40
30
15
0
0
__
1
0
60-70
" 95(c)/50(d)
60
0
0
75-80
0.4
(a) Where operators accept liability for all discharges.
(b) (e.g., AML)
(c) Anthracite
(d) Bituminous
N/A = Not Applicable
= No Response
ND = No Data
Table 6 provides information on the type of remining being conducted at the existing remining
I
operations (i.e., refuse piles, surface mine, or underground mines).
12
Introduction
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Coal Remining BMP Guidance Manual
Table 6: Characteristics of Existing Remitting Operations by State (IMCC, 1998)
State
Alabama
Alaska
Colorado
Illinois
Indiana
Kentucky
Maryland
Missouri
Mississippi
Montana
New Mexico
Ohio
Pennsylvania
Tennessee
Texas
Utah
Virginia
West Virginia
Wyoming
Totals
Number of coal
refuse piles
Active
Mines
Under
Permit
4
0
0
40
1
3
0
0
0
1
0
0
173
5-10
0
5
33
1
266-
271
AML
Projects
1
0
4
0
0
1
-_
0
0
0
0
0
0
0
38
44
Number of
surface mine sites
Active
Mines
Under
Permit
54
0
0
1.
34
1
17
2
1
11
0
2
1,278
135-
180
0
2
77
7
1,622-
1,667
AML
Projects
0
12
0
__
0
0
0
1
0
0
0
0
117
__
130
Number of
underground
sites
Active
Mines
Under
Permit
13
0
0
0
2
2
21
0
0
1
0
1
655
210-
260
0
32
107
1
1,045-
1,095
AML
Projects
_._
0
2
0
0
0
_._
0
_
2
0
0
N/A
104
__
108
Number of
remining permits
meeting BAT
Active
Mines
Under
Permit
ND
0
0
0
0
5
2
0
0
0
0
0
616
0
0
0
0
9
632
AML
Projects
1
0
0
0
__
_ _
__
0
0
_
0
__
0
0
0
N/A
2
__
3
N/A = Not Applicable; = No Response; ND = No Data.
Introduction
13
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Coal Remining BMP Guidance Manual
Best estimates of potential renaming activities according to IMCC member states are provided in
Table?.
Table 7: Potential Remining Operations by State (IMCC, 1998)
Alabama
Alaska
Colorado
Illinois
Indiana
Kentucky
Maryland
Missouri
Mississippi
Montana
New Mexico
Ohio
Pennsylvania
Tennessee
Texas
Utah
Virginia
West Virginia
Wyoming
Number of
coal refuse piles
1
3
-400
30
150
-200
10
0
0
1
N/A
(1,095 acres)
858
(182 acres)
0
5
400-450
0
Totals 2,058 - 2,108 and
= No Response
N/A = Not Applicable
1,277 acres
Number of
surface mine sites
._
5
-50
10
453
400-600
75
0
1
11
N/A
(23,000 acres)
(158,960 acres)
(46,000 acres)
0
2
750
3
0
1,760 - 1,960 and
227,960 acres
Number of
underground mined sites
1
-850
! 12
' 61?
800 - 1,000
75
i
i
i
0
1
_N/A
4,000
(3 1,587 acres)
800
0
32
800
1 ' '
1
0
7,986 - 8,186 and
31,587 acres
i '
14
Introduction
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Coal Remining BMP Guidance Manual
Existing State Renaming Programs
After more than ten years of success with state remining permit programs, abandoned mine land
reclamation, and water quality improvements in Pennsylvania and other coal mining states, it is
time to re-evaluate the regulatory conditions that were originally developed, advance the process
by offering new remining incentives, and remove disincentives embedded in the current remining
program. The goal is to develop a more efficient remining permitting process, with design-based
permit standards, that incorporate critical BMPs. The permitting incentives should be integrated
with watershed scale approaches to abandoned mine land reclamation and AMD abatement; and
risk assessment protocols should be developed to minimize liability and risk concerns of mine
operators, state and federal regulatory agencies, watershed groups, and landowners.
The recent EVICC Solicitation indicates that 7 states have issued Rahall type permits (Refer to
Table 5). Pennsylvania's remining program has issued more than 300 remining permits,
accounting for 91 percent of all the Rahall permits (Figure 1). The remaining states have issued
ten or less remining permits each.
Figure 1: Percentage of Total Number of Rahall Permits Issued by State
rAL(3.03%)
WV (2.42%)
VA(0.91%;
PA (90.91%)
MD(0.61%)
OH (0.91%)
Introduction
15
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Coal Remining BMP Guidance Manual
Below is a brief history of the development and requirements of each staters remining program.
Pennsylvania
Prior to the federal law changes in 1987, the Pennsylvania (PA) legislature amended PA SMCRA
in 1984 (Senate Bill 1309) to include remining incentives. Under the PA law and related
regulations [25 PA Code Chapter 87, Subchapter F (bituminous coal) and Chapter 88,
Subchapter G (anthracite coal)] a baseline pollution load is established, a pollution abatement
plan is submitted incorporating best technology, and the effluent limits for the pre-existing
discharges are determined by the BPJ process. From 1984 to 1988, PA Department of
Environmental Resources (PA DER), now PA Department of Environmental Protection (PA
DEP), EPA, and OSMRE, were involved in a cooperative research and development project with
' ii . ; \
the Pennsylvania State University and KRE Engineers concerning elements of the BPJ process.
The project resulted in the development of the REMINE computer program and related
publications by Smith (1988), and Pennsylvania Department Of Environmental Resources, and
others (1988).
Between 1985 and June 1997, PADEP issued 260 remining permits (Table 8 and Figure 1),
based on the following three-step process: (1) development of baseline loads; (2) submittal of a
pollution abatement plan (technologies and BMPs); and (3) development of water quality
limitations and standards based on BPJ. Of the 260 facilities issued permits, only three are
required to treat pre-existing discharges on a long-term basis to achieve compliance with the
baseline pollutant levels. Treatment can also be required to treat short-term excursions from the
baseline. Only eleven permits (4.2 percent) have ever required treatment on a temporary or long-
term basis in Pennsylvania.
An independent evaluation of the success of the PA remining program was performed by
Hawkins (1995) of the U.S. Bureau of Mines. As of 1995, the Pennsylvania remining program
successfully permitted for reclamation approximately 4,000 acres of abandoned mine land, which
led to the production of 36 million tons of coal from acres deemed "untouchable" under pre-
16 Introduction
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Coal Remining BMP Guidance Manual
renaming regulations (Hawkins, 1995). Site specific data and a project description for a key
remining site (Fisher Mining Company, Lycoming County) are found in publications by
Plowman (1989) and Smith and Dodge (1995). The authors reported that pre-remining data from
the main discharge from the Game Land site showed a medium net acidity in excess of 100
mg/L. Post remining data showed the same discharge to be net alkaline and the receiving stream
now supports brook trout. Another independent evaluation of water quality improvements and
costs of remining in Pennsylvania and West Virginia was performed by Skousen et al. (1997),
including data from ten sites, of which the largest and most significant is Solar mine near
Pittsburgh. The water quality improved at all ten sites. In all but two cases, coal mined and sold
produced a net profit for the mining company.
Table 8: Pennsylvania Remining Permits Which Required Treatment, June, 1997
(IMCC, 1997)
Permits Issued
Currently Treating
Forfeited due to AMD
Required Treatment
Bituminous Region
248
3
2
11
Anthracite Region
12
0
0
0
Totals
260
3
2
11
Figure 2: Status of 260 Pennsylvania Remining Permits (IMCC, 1997)
1 % sites treating
1 % forfeiture sites
98% not treating
Introduction
17
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Coat Remining BMP Guidance Manual
Pennsylvania has taken additional steps to encourage remining and reclamation of abandoned
mine lands. In 1997, SMCRA and 25 PA Code Chapter 86 were revised to authorize bonding
incentives, including reclamation bond credits and financial guarantees. A qualified mine
' |
Operator can earn bond credits by performing voluntary reclamation of additional mine lands.
, " i|
The credit is the operator's cost to reclaim the proposed area or DEP's cost, whichever is less.
Credits may then be applied as bond on any coal mining permit, and may be transferred and used
once after their first use.
!|
West Virginia
West Virginia has issued eight remining permits with modified water quality requirements. The
basic elements of their program are similar to those in Pennsylvania in that the applicant must
conduct water quality and quantity monitoring to establish a baseline pollutant load and must
,'. i
submit an abatement plan.
In order to receive remining approval, operators must demonstrate that their proposed abatement
plan represents the best available technology and that the operation will not cause additional
surface water pollution and will result in the potential for improved water quality. Effluent
limits in the remining permit do not allow a discharge of pollutants in excess of the baseline
pollutant load. Also, a remining water quality standard variance must be approved prior to
issuing the National Pollutant Discharge Elimination System (NPDES) remining permit. If the
variance is denied, the NPDES Remining Permit will also be denied.
Maryland
1
Although Maryland has a relatively small coal industry, the State actively implemented the
Rahall amendment, which allows for a modified NPDES permit for remining operations.
' , . , !
Maryland also implemented EPA revegetation standards allowing for bond release after 2 years,
i ,, i
and offers reduced bonding rates for an NPDES remining permit. Currently, Maryland has
18
Introduction
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Coal Remining BMP Guidance Manual
issued two remining permits with relaxed effluent limits. Maryland has numerous remining
operations on previously mined areas with no pre-existing discharges.
Virginia
Virginia has regulations for remining and has issued three permits with relaxed effluent limits for
remining operations. Operators must show that remining operations have the potential to
improve water quality. To obtain a remining permit, the applicant submits baseline monitoring
data, a module of REMINE, and an abatement and reclamation plan. Permits are based on BPJ
determined by the output of REMINE and must result in a reduction in pollutant loading to the
stream.
Kentuclcy
Kentucky has regulations for remining and has issued four permits with relaxed effluent limits
for remining activities. The Kentucky procedure is much like that described for the other states
above. The applicant submits baseline monitoring data, an abatement and reclamation plan, and
may submit a module of REMINE. Operators must show that remining operations have the
potential to improve water quality. Permit limits are based on BPJ and must result in a reduction
in pollutant loading to the stream (Veil, 1993).
Tennessee
Tennessee does not administer its coal mining program. OSMRE maintains the authority to issue
coal mining permits. As of 1993, about 60 percent of all coal mining permits in the state
involved remining, however, no permits were issued with relaxed effluent limits.
Ohio
Ohio has regulations for remining and has issued three permits with relaxed effluent limits for
Introduction
19
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Coal Remitting BMP Guidance Manual
remining activities. Remining approvals are limited to sites with pre-existing discharges.
" ' ' ' ' !
Operators must submit baseline monitoring data along with a pollution abatement plan and
supplemental hydrological information. Permit approval is contingent on the abatement plan
representing BAT and having the potential to reduce the baseline pollutant load (Veil, 1993).
I
Alabama
I
Alabama has issued 10 permits' with relaxed effluent limits for remining operations. To qualify
for a remining permit an operator must show:
!i
:, : I
i
Original mining/disturbance must have occurred prior to 1977.
Subsequent permitted/legal disturbance could not have occurred after 1977.
Areas that have had a SMCRA permit or bonding at anytime are not eligible.
Substantive showing must be made that water quality can be improved ( a
pollution abatement plan must be submitted).
i
Effluent limits must at least meet ambient water quality standards.
Modified requirements for pH, iron and manganese must apply the best available technology
economically achievable on a case-by-case basis, using best professional judgement, to set
specific numerical effluent limits in each permit.
Regulatory agencies for states where remining is not currently practiced may be inclined to start
and promote remining programs if such programs can be shown to be successful in terms of
enhanced coal recovery, reclamation of abandoned mine lands, and reduction of (or no net
increase in) mine drainage. Mine operators also may be more inclined to enter into remining
projects with the knowledge that the potential of incurring liability for long-term treatment of
mine waters from prior mining activities is low.
20 Introduction
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Coal Reminins BMP Guidance Manual
Introduction to Best Management Practices
Remining is the mining of abandoned surface mines, underground mines, and/or coal refuse piles
that were mined prior to the environmental standards imposed by the Surface Mining Control and
Reclamation Act of 1977. There are four types of abandoned mine lands available for renaming
operations: (1) sites that were previously surface mined, (2) sites that were previously
underground mined, (3) sites that were previously surface mined and underground mined, and (4)
sites that had coal refuse deposited on the surface. These sites were typically left unreclaimed and
unvegetated, sometimes pose safety hazards and are often associated with pollutional discharges
or sedimentation problems. Because of associated environmental problems, these areas cannot
be re-affected or remined without the implementation of minimal best management practices
(BMPs) in an attempt to correct past problems.
BMPs implemented during the remining and reclamation of these sites are designed to reduce, if
not completely eliminate, these pre-existing environmental problems, particularly water
pollution. The types and scope of BMPs are tailored to specific operations based largely on pre-
existing site conditions, hydrology, and geology. BMPs are designed to function in a physical
and/or geochemical manner to reduce the pollution loadings.
In this guidance document, BMPs have been placed into four categories: hydrologic and
sediment control, geochemical, operational, and passive treatment, although there is some
question whether passive treatment is a true BMP. These categories have been designed for ease
of discussion, and each BMP has been placed in the category that is most appropriate. In several
cases, a BMP serves more than a single function. For example, induced alkaline recharge
trenches are discussed as a geochemical BMP, but also influence hydrology and are closely
related to some passive systems. Adding to this complexity is the fact that remining operations
nearly always employ multiple BMPs in an effort to abate pollution.
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Coal Reminins BMP Guidance Manual
Physically-performing BMPs function to limit the amount of ground water that is ultimately
discharged from the mine and by reducing erosion and subsequent off-site sedimentation by
controlling surface-water runoff. Discharge reduction is performed by limiting the amount of
ground and surface water that laterally or vertically infiltrates into the backfill. Water is routed
away from spoil via regrading, diversion ditches, low-permeability seals and caps, and highwall
and pit floor drains. Ground water that has entered the spoil is collected and drained away via
floor drains. Some physical BMPs are performed to reduce ground-water flow, some to reduce
erosion and sedimentation problems, and some serve both purposes. Physical BMPs are
addressed in Section 1.0 (Hydrologic and Sediment Control Best Management Practices). Below
:! i
is a list of physically performing BMPs and an indication whether they influence ground-water
hydrology (gw), erosion and sedimentation (e&s) or both (gw, e&s).
Regrading of spoil (gw, e&s)
Revegetation (gw, e&s)
Diversion ditch installation (gw, e&s)
installation of low-permeability caps (gw)
I : !
Stream sealing (gw)
Underground mine daylighting (gw)
Mine entry and auger hole sealing (gw)
i
* Highwall and pit floor drains (gw)
Grout curtains (gw)
Ground water diversion wells (gw)
i ' i i
Advanced erosion and sedimentation controls (e&s)
I
Geochemically-performing BMPs function to inhibit pyrite oxidation, reduce the contact of water
with acid-producing materials, inhibit iron-oxidizing bacteria, or increase the amount of
alkalinity generated within the backfill. Pyrite oxidation is inhibited by limiting its exposure to
I I
the atmosphere and preventing the proliferation of iron-oxidizing bacteria with bactericides.
Acidic materials are special handled or capped to isolate them from the ground-water flow path.
Alkaline materials are imported, redistributed, and strategically placed in the ground-water flow
path in order to increase and/or accelerate alkalinity production. Geochemical BMPs are
.._ | , L
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Coal Reminins BMP Guidance Manual
discussed in Section 2.0 (Geochemical Best Management Practices). Geochemically-performing
BMPs include:
Alkaline addition
Alkaline redistribution
Mining into highly-alkaline strata
Induced alkaline recharge
Special handling of acid-forming materials
Special handling alkaline materials
Use of bactericides
Operational BMPs are mining practices that can reduce the risk of pollution or erosion and
sedimentation problems. Rapid mining and concurrent reclamation limit the exposure of acid-
forming materials to weathering and promote rapid reclamation and revegetation that can reduce
erosion and sedimentation problems. Coal refuse reprocessing removes an acid-producing
material.. This material is burned to produce electricity, and the ash that is produced, which is
frequently alkaline, is returned to the site where it can neutralize acid. Operational BMPs are
discussed in Section 3.0 (Operational BMPs). They include:
Coal refuse reprocessing
Rapid mining and concurrent reclamation
Limited or no auger mining
Off-site disposal of acid-forming coal cleanings, pit and tipple refuse
The last category, passive treatment, encompasses a variety of engineered treatment facilities that
require minimal maintenance, once constructed and operational. Passive treatment generally
involves natural physical, biological and geochemical actions and reactions. The systems are
commonly powered by water pressure created by differences in elevation between the mine
discharge point and the treatment facilities. Passive treatment does not meet the standard
definition of BMPs in that they are typically end-of-pipe (treatment) solutions. They are included
in this manual because they can be used as part of the overall abatement plan to reduce pollution
Best Management Practices
23
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Coal Reminins BMP Guidance Manual
loads discharging from remining sites. Passive treatment methods are discussed in Section 4.0
(Passive Treatment Technologies). Types of passive treatment include:
anoxic limestone drains
constructed wetlands
successive alkalinity-producing systems
open limestone channels
oxic limestone drains
alkalinity-producing diversion wells
pyrolusiteฎ systems
Site Characteristics and BMP Selection
Factors that influence which BMPs can be employed effectively at remining sites include
1 s
previous types of mining activities, geologic and hydrologic characteristics of the site, the quality
and quantity of pre-existing discharges, economics, and regional differences. Listed below under
I
these categories are examples of associated BMPs and some of their limitations:
Previous mining history
i
Daylighting only occurs where previous underground mining was conducted.
Mine sealing is used where underground mines or auger holes are not completely
daylighted.
* Regrading and revegetation are performed on abandoned and reclaimed surface mines.
Coal refuse reprocessing occurs where there are abandoned coal refuse piles.
Geologic and hydrologic characteristics
Alkaline addition is conducted where there is an inadequate quantity of naturally-
occurring alkaline rocks.
Alkaline redistribution takes place where only a portion of the site has a significant
amount of alkaline material which is then distributed more evenly across the site.
i
I
^ I
24 Best Management Practices
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Coal Reminins BMP Guidance Manual
9 Alkaline material that is located stratigraphically high above the coal may require mining
into higher cover to access it or may require a reorientation of the pit so that the alkaline
material is encountered with every mining cut.
Special handling of acidic material occurs where there is a significant amount, but not an
over abundance, of this material that can be field-identified and segregated.
Highwall drains are not an option where no up-gradient final highwall remains.
Hydrologic controls, such as floor drains or ground-water diversion wells, are not
necessary unless lateral recharge is present.
The site may be capped with a low-permeability material, if vertical recharge is predicted
to be the main source of water to the backfill and a low-permeability material is readily
available.
Passive treatment may be used, if the topography to drive the system is present and
sufficient construction space is available.
Pre-remining water quality and quantity
Large volumes of severely degraded water may not be suitable for a passive treatment
BMP.
High volumes of water flowing from underground mines that will not be completely
daylighted may be suited to rerouting (piping) through the spoil.
Highly acidic pre-remining discharges associated with pyritic overburden may require
substantial alkaline addition and/or special materials handling.
Economics
Cost plays a substantial role in determination of which BMPs are employed and the degree to
which they are implemented. Remining sites are commonly economically marginal because of
reduced coal recovery rates compared to virgin sites. These sites also generally entail greater
reclamation costs due to pre-existing site conditions. Therefore, economics plays a significant
role in the development of a BMP plan. The BMP plan is weighed against these costs. If the cost
of BMP implementation is prohibitive the site will not be remined. Mining only occurs on sites
where a profit can be made.
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Coal Reminins BMP Guidance Manual
Regional Differences
I
There are also regional considerations that play into the decision of which BMPs to use at a
particular site. Differences in the geology, geochemistry, hydrology, and topography between
coal regions cause distinct problems requiring differing solutions. Regional differences include:
Geologic conditions that effect the type (lithology) and chemistry/mineralogy of rocks
,j
and the structure (e.g., folding, faulting, and fracturing).
Hydrologic conditions, such as differences in local and regional ground-water flow
systems and precipitation amounts, frequency, and/or duration.
'!
Differences in topography (such as amount of relief and steepness of slopes).
ii i
Differing surface and underground mining techniques, thus abandoned sites will exhibit
distinct problems regionally.
Acid Mine Drainage
It has been recognized for decades that acid mine drainage (AMD) is to a large extent a regional
problem that is most prevalent in the northern Appalachians. Upon closer examination it was
evident that the problem was frequently associated with the Allegheny Group coals (Appalachian
; . |. . i
Regional Commission, 1969). Figure 3 illustrates the percentage of streams within various
Appalachian watersheds that had pH less than 6.0. Figure 4 shows the percentage of streams for
'!
these same watersheds that have sulfate greater than 75 mg/L. The cut-offs of pH 6.0 and 75
mg/L sulfate were chosen by the US Geological Survey because low pH and elevated sulfate can
i
indicate impacts from coal mine drainage.
Watersheds with 35 percent or more of streams with pH less than 6.0 occur in the northern
Appalachians and are associated with the outcrop areas of the Allegheny Group. Typically the
watersheds in the southern Appalachians have 10 percent or less of steams with pH less than 6.0.
26
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Coal Reminins BMP Guidance Manual
The distribution of watersheds with a high percentage of streams with greater than 75 mg/L
sulfate does not necessarily correspond with the low pH areas. For example, one of the
watersheds in eastern Kentucky had 57 percent of streams with sulfate greater than 75 mg/L, but
no stream measured had pH less than 6.0. Other watersheds show similarly high percentages of
streams with sulfate greater than 75 mg/L, but with few streams with pH less than 6.0. This type
of water is characteristic of neutralized acid mine drainage.
No full explanation as to the water quality differences within the Appalachian Basin has been
provided to date, but there is little question that it is due to geologic differences. Cecil and others
(1985) examined sulfur data for coals from southern West Virginia to Pennsylvania. The
stratigraphically older coals, which occur in southern West Virginia, have lower sulfur than the
younger coals that occur in the northern Appalachians (Figure 5). Cecil and others attribute these
differences to climatic factors at the time of peat (coal) deposition that influenced the chemistry
of the swamp, which ultimately influenced the sulfur content of the coal.
The production of acidity from pyritic sulfur is only half the story. The other half of the story is
the production of alkalinity from carbonate dissolution. Calcareous rocks neutralize acid and they
are the explanation for the water quality in streams that have pH greater than 6.0 and sulfate
greater than 75 mg/L (i.e., neutralized mine drainage).
It is evident that in some regions AMD is a significant problem, while in other areas it is rare.
This difference is an important factor in remining. Where AMD is prevalent, water quality is an
important remining issue. Where AMD is rare, water quality typically less of a concern, with the
possible exception of sedimentation problems.
Best Management Practices
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Coal Reminins BMP Guidance Manual
Figure 3: Percentage of Streams with pH < 6.0 for 24 Watersheds in the Appalachian
Basin (data from Wetzel and Hoffman, 1983).
Percentage of Streams in the Watersheds
with a pH less than 6.0
N
W-^-E
S
100
200 Wiles
/ x/ States
% of Streams
Q2-io
35-56
28
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Coal Remining BMP Guidance Manual
Figure 4: Percentage of Surface Water Sample Stations with Sulfate Greater than 75
mg/L for 24 Watersheds in the Appalachian Basin (data from Wetzel and
Hoffman, 1983).
PITTSBURGH
SANDSTONE-REDSTONE-LIMESTONE TIME
50 100 km.
PRESERVED LIMIT OF
PITTSBURGH COAL
LAKES AND MUD FLATS
LAKES AND SWAMPS
SUBDELTAS
ALLUVIAL PLAIN
Best Management Practices
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Coal Reminine BMP Guidance Manual
Figure 5: Stratigraphic Variation of Sulfur Content of 34 Coal Beds of the Central
Appalachians. (Figure from Cecil and others, 1985).
DUNKARD
MONONGAHELA
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SULFUR
(Weight Percent)
Hydrology
The ground-water hydrology is similar throughout much of the Appalachian Plateau, however
' : " ' ' I
there are some subtle differences region to region. Some of these differences are related to
changes in major rock types associated with the coal which in turn directly impacts the fracturing
density, interconnectedness of fractures, depth of fracturing, and aperture size of the fractures.
i
For example, experience has shown that in shallow cover (<200 ft), the massive, well-cemented
sandstones commonly associated with coals of eastern Kentucky tend to exhibit much less
fracturing than is observed in the more thinly-bedded, poorly-cemented sandstones associated
30
Best Management Practices
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Coal Reminins BMP Guidance Manual
with the Pittsburgh coal in northern West Virginia. These differences will be reflected in the
ground-water flow systems (location of ground water, amounts in storage, and ground water
movement velocity) of the respective areas.
Additionally, the ground-water systems associated with the mid-Western coals in Indiana and
Illinois are primarily regional in nature and near surface. Whereas, ground-water systems in the
Appalachian Plateau are characterized by a series of limited-area perched aquifers underlain by
deeper more regional systems that discharge to the major rivers and creeks of the area (e.g.,
Monongahela, Kanawha, or Tug Fork rivers).
Topography and Geomorphology
Regional differences in topography and geomorphology can impact the types of BMPs employed.
For example, the topography of southern West Virginia, western Virginia, and eastern Kentucky
is generally steep with narrow V-shaped valleys and sharp-peaked hills and mountains. Figure 6
shows this type of topography in Kanawha and Raleigh Counties in southern West Virginia.
Whereas, the topography of northern West Virginia and western Pennsylvania is not nearly as
steep-sloped with broader valleys and more flat-topped hills and mountains. Figure 7 illustrates
this topography in Jefferson County in west-central Pennsylvania. These differences have
resulted in distinctive mining techniques and post-mining configurations. For example, the steep
sloped areas tended to promote contour surface mining (Figure 8), whereas in shallower sloped
areas block cut or area mining was used more frequently (Figure 9).
Mining Methodology
Differences in mining methods in turn can result in greatly differing abandoned mine site
conditions, and thus may require distinct BMP engineering plans to effect water quality
improvement. For example the steep-sloped areas may require additional ditches, check dams
and ponds for stabilizing, while regrading and revegetating a shallower sloped area may be
adequate to stabilize erosion. Abandoned mines in southern West Virginia, western Virginia,
and eastern Kentucky frequently exhibit down slope spoil disposal, open pits, and exposed
highwalls making reclamation back to the approximate original contour (AOC) impractical in
Best Management Practices
31
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Coal Reminine BMP Guidance Manual
most cases. Abandoned mines in northern West Virginia and western Pennsylvania will have
some open pits and exposed highwalls, but are commonly characterized by a series of
unreclaimed spoil piles and ridges. Returning the site to AOC is generally more feasible on these
sites.
Figure 6: Example of Steep Topography and High Relief in Southern West Virginia
Showing Multiple Contour Strip Mines on Steep Slopes.
IT^fefc*,
32
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Coal Reminine BMP Guidance Manual
Figure 7: Example of Moderate Slopes and Broader Valleys and Hilltops in West-
central Pennsylvania Showing Small Area Mines.
Best Management Practices
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Coal Reminins BMP Guidance Manual
Figure 8: Topographic Map Illustrating Contour Surface Mining.
{ 'f, " ' ' i ' i \ S> , 1 i'l I; t / / f / .'^-
34
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Coal Reminins BMP Guidance Manual
Figure 9: Topographic Map Illustrating Area Surface Mining.
The "shoot and shove" method of past mining on the steep slopes of the central Appalachian
Plateau has resulted in erosion and sedimentation problems.
Best Management Practices
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Coal Reminins BMP Guidance Manual
BMP Implementation
The best BMP plan may fail if it is not implemented as designed (e.g., conducted properly,
i: ' ij
adequately, and on a timely basis) and as approved by the permitting authority. To facilitate field
implementation, the BMP plan should be clearly thought out and designed for site-specific
conditions during the permit application process. A well designed plan can eliminate the need
f' , ' - ' , I
for revisions once the permit is issued and will provide guidance to ensure proper
implementation. However, a well designed plan also provides a degree of flexibility to allow for
"mid-stream" changes caused by unforeseen circumstances.
!|
An effective BMP plan hinges greatly on a detailed site assessment. Site assessment data and
i , , | .
information should be sufficient to identify which strata will require handling, potential sources
I '! ' ' . , '.,.' I
6f ground water, probable reasons for existing AMD, the scope of previous mining, and other
'? i J ' ' '., Ih
Salient data. Site assessment will typically, at a minimum, require extensive field work and
: ' 'i :!i ' : " " .1
mapping, multiple bore holes with appropriate vertical sampling, ground-water level
! ,1 , |
measurements, surface water flow measurements, and representative ground- and surface-water
samples. ' - '
i
! . i
A BMP plan should be realistic. It should be appropriate to the site, workable in the field,
j . .
economically feasible, and based on sound scientific principles. Plans should be clearly designed
with appropriate maps, cross-sections and narrative. The ultimate viability of a BMP plan
depends heavily on the individual(s) that develops the BMP plan, the one(s) that review and
i
i
approve it, those who implement it, and those who enforce it. The BMP plan should be verifiable
and enforceable by those individuals who inspect the site. Implementation guidelines are
provided for each category of BMPs in the appropriate sections.
": ' "i i
Efficiency
The efficiencies of BMPs or groups of BMPs, in regards to decreasing pollution loadings, are
based on limiting one or more of the following factors:
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Best Management Practices
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Coal Reminins BMP Guidance Manual
amount of pyritic material
availability of oxygen to the pyritic material
contact of water with the pyritic material
Previous studies (Smith, 1988 and Hawkins, 1995), have shown that controlling (decreasing) the
flow of AMD discharges exerts the largest influence on the reduction of pollution load. Flow
reduction is best accomplished by reducing surface- and ground-water infiltration. However,
prevention of additional acid formation by use of geochemically-based BMPs can also decrease
the pollutant concentration which will likewise decrease the associated loading. BMPs can also
function by treatment (neutralization) of AMD after it has formed. This treatment can be in-situ
neutralization from contact with additional alkaline materials or can be in the form of end-of-the-
pipe treatment performed by passive treatment systems.
Some BMPs function in more than one way. Underground mine sealing will not only inhibit
ground-water movement, it will also attenuate oxygen infiltration. Alkaline addition can prevent
AMD through inhibition of iron-oxidizing bacteria and it can neutralize acidity once it has been
produced. Surface- and ground-water controls can reduce erosion and sedimentation, while
inhibiting infiltration into the spoil.
Efficiencies of BMPs are discussed in the sections dealing with each BMP category and are
evaluated by the observed and statistical approaches described in Section 6.0 (Efficiencies of
Best Management Practices).
Verification
Proper implementation of BMPs can be critical to the environmental success or failure of a
remining site. Thus, it is imperative that the BMPs be implemented as planned. It is the role of
the regulatory inspection staff to verify and enforce the provisions outlined in the BMP plan of a
remining permit. The inspector generally does not need to be present at all times to assess the
implementation of the BMPs in this document. However, some BMPs will require more detailed
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Coal Remitting BMP Guidance Manual
and more frequent inspections than others. It is also incumbent on the mine operator to ensure
that the BMPs are implemented as designed and to provide the proper documentation (e.g.,
I
material weigh slips, receipts, laboratory analyses, etc.) where necessary. Guidelines for
, j
verification for each BMP category are provided in the appropriate section of this manual.
i
ij
Monitoring of the water quality and quantity is the truest measure of BMP effectiveness. If the
discharges exhibit lower pollution loadings, this is an indication that the BMPs were successful
,; i
with all other factors being equal.
i
Monitoring and inspection of BMPs to verify site conditions and implementation should be a
requirement of any remining operation. Verification includes:
Direct measurement of flow and water sampling for contaminant concentrations before,
during, and after reclamation.
' ' ! ' I " ! '
Monitoring should continue beyond the initial water table re-establishment period (e.g., at
."! '!'' , , " I . ! I '
least 2 years after backfilling).
Evaluation of water quality and quantity data at hydrologically-conneeted units and/or
discrete individual discharges, so trends caused by remining can be assessed.
: I i ;
Hydrologic data should be reviewed with respect to climatic (i.e. precipitation)
conditions.
1 I -
Assessment of deviations from the approved implementation plan.
Inspection of critical stages of the BMP implementation plan, such as during special
. "i :*, ' I I I ''
materials handling, alkaline addition, drain installation, or mine entry sealing.
Inspection should assure, where required, proper maintenance is performed.
! ' ' " I
Review of material weigh slips, receipts, laboratory analysis, and other necessary
documentation.
a i
Assessment of BMP stability over time.
Periodic site evaluation to ensure the BMP plan is appropriate to on-site conditions. This
evaluation should include, at a minimum, assessment of water quality and quantity, site
; ' i
physical and geologic conditions, and impacts of significant storm events.
j
38 Best Management Practices
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Coal Reminins BMP Guidance Manual
Adequate inspection, hence verification, is necessary to ensure that BMPs are being performed as
proposed. Remining operation inspections will also provide information as to changing site
conditions (anticipated and unanticipated) as well as unexpected developments.
Verification also will provide additional data for on-going assessment of the efficiency of
individual BMPs as well as BMP combinations. The analyses of these data will foster continuing
improvement of the BMPs which will ultimately lead to more efficient ways of decreasing
pollution loadings.
This manual is designed to:
describe the BMPs that are available for remining operations.
define the appropriate circumstances for the BMPs.
explain how each BMP functions to diminish the pollution load.
discuss how a BMP works or in conjunction with other BMPs.
give details of BMP construction and installation specifics, size and scope of a particular
BMP, and the required materials.
present actual data from remining case studies employing various BMPs.
discuss relative frequency of use for each BMP.
give estimates of the cost of employing each BMP.
present projected efficiencies of specific BMPs based on a database of 116 completed
sites in Pennsylvania, case studies, and published research.
References
Appalachian Regional Commission, 1969. Acid Mine Drainage in Appalachia. Appalachian
Regional Commission, Washington, DC, 210 p.
Brady, K.B.C., R.J. Hornburger, and G. Fleeger, 1998. Influence of Geology on Postmining
Water Quality: Northern Appalachian Basin. Chapter 8, Coal Mine Drainage Prediction and
Pollution Prevention in Pennsylvania. Pennsylvania Dept. of Environmental Protection.
Best Management Practices
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Coal Remining BMP Guidance Manual
Cecil, C.B., R.W. Stanton, S.G. Neuzil, F.T. DuLong and B.S. Pierce, 1985. Paleoclimate
controls on Late Paleozoic sedimentation and peat formation in the central Appalachian Basin.
International Journal of Coal Geology, v. 5, p. 195-230.
Hawkins, J. W., 1995. Characterization and effectiveness of Remining Abandoned Coal Mines in
Pennsylvania. U.S. Bureau of Mines, Report of Investigations - 9562, 37 pp.
; , : , : ' ' 1 . ' ' I"
mi' " ;| :
Interstate Mining Compact Commission (IMCC), 1997. Discussion Paper on Water Quality
Issues Related to Remining. Presented at the IMCC meeting conducted July 8, 1997, amended
September 1997 for presentation at IMCC annual meeting conducted September 15, 1997, 5 pp.
.-I1 l"1" i '" ' "!.;, i I,' I
Interstate Mining Compact Commission (IMCC), 1998. Solicitation to Members, September 3,
1998.
Lineberry, G.T., K.F. Unrug, and D.E. Hinkle, 1990. Estimating Secondary Mining Potential of
Inactive and Abandoned Appalachian Highwalls. Lit. J. Surf. Min. Reclam., v. 4, pp. 11-19.
": . j ' - :.
' ' , i. . , . ;P.' ' I
Office of Surface Mining, Reclamation and Enforcement (OSMRE), 1998. Electronic copy of
AMLIS database, current as of September 23, 1998, dBase file format called ALLPADS.dbf,
14,307,960 bytes.
I :
i ,'. i
Office of Surface Mining, Reclamation and Enforcement (OSMRE), 1999. Unreclaimed
Problems. Abandoned Mine Land Program, http://www.osmre.gov/zintroun.htm Updated
11/13/98,2pp.
Pennsylvania Dept. Of Environmental Resources, Penn. State Univ., and Kohlman Ruggiero
Engineers, 1988. Coal Remining - Best Professional Judgement Analysis. Prepared for USEPA
Office of Water and PA Dept. Of Envir. Res., November 1988.
i""i "Hi ,. " ,.
.If. ' iin
Plowman, W., 1989. New Light on an Old Problem. Game News, May 1989, 6pp.
' i
Skousen, J., R. Hedin, and B. Faulkner, 1997. Water Quality Changes and Costs of Remining in
Pennsylvania and West Virginia. Paper presented at the 1997 National Meeting of the American
Society for Surface Mining and Reclamation, Austin, Texas, May 10-15, 1997.
Skousen, J., T. Hilton, and B. Faulkner, 1999. Overview of Acid Mine Drainage Treatment with
Chemicals. West Virginia Extension Service, http://www.edu/~agexten/landrec/chemtrt.htm 15
PP- ;:" ,\ '' '" j1
Smith, M.W., 1988. Establishing Baseline Pollution Load from Pre-existing Pollutional
Discharges for Remining in Pennsylvania. Paper in Mine Drainage and Surface Mine
Reclamation. H. Mine Reclamation, Abandoned Mine Lands and Policy Issues. USBM 1C 9184,
pp.311-318.
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Coal Reminins BMP Guidance Manual
Smith, M.W. and C.H. Dodge, 1995. Coal Geology and Remining, Little Pine Creek Coal Field,
Northwestern Lycoming County. PADEP Guidebook, pp. 13-26.
U.S. Environmental Protection Agency Region in and Office of Surface Mining, 1997. Cleaning
Up Appalachian Polluted Streams. 1996 Progress Report, USEPA Region m and OSM,
September 1997, 54 pp..
U.S. Department of Energy (DOE), 1997. Coal Industry Annual. Energy Information
Administration, DOE/EIA-0584(97), 256 pp.
U.S. Department of Energy (DOE), 1999. Annual Report of the Council on Environmental
Quality, http://ceq.eh.doe.gov/reports/1993/chap7.htm 24 pp.
USGS, 1996. Assessing the Coal Resources of the United States. Factsheet FS-157-96,
http://energy.usgs.gov/factsheets/nca.html, p.2.
USGS, 1998. Biology in Focus. Biological Resources Division, April 1998, 4 pp.
Veil, J.A., 1993. COAL REMINING: Overview and Analysis. Prepared for U.S. DOE under
Contract W-31-109-ENG-38, 37 pp.
Wetzel, K.L. and S.A. Hoffman, 1983. Summary of surface-water quality data, Eastern Coal
Province, October 1978 to September 1982. US Geological Survey Open-File Report 83-940,
p.67.
Zipper, C.E. and B. Lambert, 1998. Remining To Reclaim Abandoned Mined Lands: Virginia's
Initiative. Presented at 15th Ann. Meeting of the Amer. Society for Surface Mining and
Reclamation. May 17-22, 1998. St. Louis, 8pp.
303(d)PA, 1998. Commonwealth of Pennsylvania Section 303(d) List. Pennsylvania Department
of Environmental Protection, July 23, 1998.
303(d)WV, 1998. West Virginia, Division of Environmental Protection, Office of Water
Resources, Supplement to West Virginia 303(d)
303(d)AL, 1998. Alabama Department of Environ. Management 303(d) List. August 26, 1998.
303(d)VA, 1998. Virginia 1998 303(d) Total Maximum Daily Load Priority List and Report.
Prepared by the Dept. Of Envir, Quality and the Dept. Of Conservation and Recreation,
Richmond, VA, October 1998.
Best Management Practices
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303(d)KY, 1998. 303(d) List of Waters for Kentucky. Kentucky Natural Resources and
Environmental Protection Cabinet, Division ofWater, June 1998.
303(d)TN, 1998. Proposed Final 1998 303(d) List. Tennessee Department of Environment and
Conservation, Nashville, Tennessee, June 1998 (Revised July).
42
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Section 1.0: Hydrologic and Sediment Control BMPs
Introduction
Controlling physical hydrologic aspects constitutes a substantial portion of the Best Management
Practices (BMP) that are employed at remining sites. Reduction of the pollution load yielded
from abandoned mines by remining has shown that reduction of the flow rate is the most salient
factor (Smith, 1988; Hawkins, 1994). Where site conditions permit recharge to the ground-water
system to be controlled through mining practices and engineering techniques, the discharge flow
rate will likewise be reduced. The diminished flow rate will in a majority of cases cause a
quantifiable decrease in the pollution load. Although contaminant concentrations from coal
mining sources frequently exhibit an inverse relationship to flow, pollution load reductions are
more commonly recorded, even when moderate increases to the contaminant concentration occur
in conjunction with a discharge flow rate reduction.
BMPs that ultimately are responsible for reducing discharge flow rates include'various means of
reducing the infiltration of precipitation and surface waters, impeding or intercepting the
movement of ground water from adjacent areas unaffected by remining activities, and providing
a means to collect and rapidly remove ground water (Hawkins, 1995a). There are a battery of
BMP methods that can be employed to impede recharge to mine spoil. These BMPs are
subdivided into two main categories: the exclusion of infiltrating surface water and the exclusion
of laterally-migrating ground water.
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1.1 Control of Infiltrating Surface Water
Methods that decrease surface-water infiltration include, but are not limited to, spoil regrading
(for elimination of closed-contour depressions and the promotion of runoff), installation of
diversion ditches, capping the spoil with a low-permeability material, surface revegetation, and
stream sealing. Prior to remining, abandoned sites commonly have unreclaimed pits and closed-
contour depressions in poorly-sorted spoil that serve as recharge zones for significant quantities
of infiltrating surface water. For many abandoned surface mines, the act of regrading, resoiling,
and revegetating spoil significantly reduces surface-water infiltration and increases runoff just by
the elimination of recharge zones and enhanced evapotranspiration. These three actions are the
more commonly employed BMPs during remining, because they are an integral part of the
remining and reclamation process. Additional means by which surface-water infiltration can be
restricted are prevention of surface water infiltration by the installation of diversion ditches,
stream reconstruction and sealing, and capping of the backfill with an low-permeability material.
Theory
Initially after reclamation, diffuse recharge from the surface through soil is generally well below
pre-mining levels because of the destruction of soil structure, soil compaction by mining
equipment, and low-vegetative growth, all of which tend to promote surface-water runoff rather
than infiltration (Razem, 1983; Rogowski and Pionke, 1984). Wunsch and Dinger (1994) noted
that, during re-excavation, spoil within a few inches of the surface was dry indicating little
infiltration was occurring. Decreases in recharge also may be facilitated by increases in porosity
in the unsaturated zone (Razem, 1984). Flow-duration curves show that after mining receiving
streams have reduced base flows, which indicate that recharge is decreased (29 percent less than
pre-mining levels) and surface runoff is increased (Weiss and Razem, 1984). After this initial
period, as soil structure and vegetation re-establishes, diffuse recharge from the surface begins to
increase. This may coincide with observed increases in hydraulic conductivity after 30 months.
The slow recovery of the water table during this period may be linked to decreased recharge
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shortly after reclamation and to increased effective porosity and permeability of the spoil.
Increased porosity permits more of the infiltrating water to become stored within the aquifer.
> , ! l! I . -!
? . , i
" ll! ' ' ,. ' 1 . " ';
Some of the recharge from the surface during this early period occurs through discrete openings
or voids that are exposed at the surface (Hawkins and Aljoe, 1991; Wunsch and Dinger, 1994).
Surface-exposed voids facilitating ground-water recharge also have been observed at a surface
mine in central Pennsylvania that has been reclaimed for over 15 years. Surface runoff flowing
1 "" ! ' , ' ' . i
across the mine surface enters the spoil through these exposed voids and flows rapidly downward
"'ii". v , ii .... '*, li , ' ' l
,11 , ,] f , !
via conduits to the saturated zone. This observation illustrates that these exposed voids continue
to receive significant amounts of recharge long after final reclamation, re-establishment of the
soil structure, and successful revegetation.
Oilier researchers contend that mining may improve the recharge potential from undisturbed
:; , , , i
areas (Cederstrom, 1971). Herring (1977) observed that overall recharge and surface water runoff
to reclaimed surface mines in the Illinois Basin were greatly increased. Herring attributes the
increased recharge to the dramatic increase in permeability of the cast overburden. Herring also
observed a four-fold increase in recharge from mining one half of a watershed hi Indiana. It is
important to note that these two studies did not address the impact of mining on the soil horizon
1 ' 'll, i , , ป - ll1 I
as discussed by Razem (1983,1984). Once infiltrating water has passed through the soil horizon,
i:. .; \. , ,' r, i, ' '! .
it appears that the recharge potential is dramatically increased. In order for surface water
infiltration to be prevented, the water should be intercepted before it percolates through the soil
and enters the highly permeable spoil beneath.
Strode (1998) wrote:
The practical reality of this is that in ... humid areas where precipitation exceeds
evapotranspiration, virtually all mine sites will receive ground water recharge and
generate drainage - acidic or alkaline. That there may be no obvious springs or seeps
does not imply that there is no drainage from the site. To illustrate what 15 inches (3 8
cm) of infiltration per year means in terms of the quantity of mine drainage which
can be generated, each acre of spoil surface would produce an average flow rate of
0.75 gpm (2.84 L/min). A 100-acre surface mine, then, would yield 75 gpm (284
L/min) of ground water flow.
j '
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Unreclaimed abandoned spoil piles and ridges may permit infiltration approaching 100 percent of
the precipitation falling on the site. Some of this water will be removed as direct evaporation, but
most will recharge the spoil. Infiltration rates and amounts are directly related to ground slopes,
particle sizes, sorting, lithology, and degree of weathering. Larger particles tend to create larger
pore spaces, thus permitting rapid infiltration of substantial volumes of water. Poorly-sorted
spoils likewise permit large volumes of water to infiltrate quickly, compared to well sorted fine-
grained spoils. Well-cemented sandstones tend to break into and remain as large fragments, thus
forming a relatively transmissive material. Conversely, many shales of the Appalachian Plateau
tend to break and weather rapidly to relatively small fragments and clays creating a somewhat
poorly transmissive environment (Hawkins, 1998a).
Mine spoil is a poorly sorted, unconsolidated material composed of angular particles ranging
from clay-sized (less than 2 microns) to those exceeding very large boulders (greater than 2
meters). Because of the broad range of particle sizes and poor sorting, spoil tends to be highly
porous and transmissive. Testing in mine spoil has recorded porosity values exceeding 15 percent
for mine sites reclaimed for more than 10 years (Hawkins, 1995a). The porosity of recently
reclaimed spoil may approach a spoil swell factor of 20 to 25 percent (Cederstrpm, 1971).
Aquifer testing in the Appalachian Plateau indicates that the transmissive properties of spoil tend
to be more than two orders of magnitude (100 times) greater than that of undisturbed parent rock
(Hawkins, 1995a). Some of the recharge from surface water occurs through discrete openings or
voids exposed at the surface across a backfill (Hawkins and Aljoe, 1991; Wunsch and Dinger,
1994). Surface runoff from a precipitation event, flowing across the mine surface, will combine
in rivulets, enter the spoil through these exposed voids, and flow rapidly downward via conduits
to the saturated zone. The action of this water rapidly flowing in from the surface tends to
increase the size and conductivity of these holes through the piping of finer grained sediments. In
some instances, infiltrating water will reappear a short distance away (e.g., 300 feet) as a high-
flowing ephemeral spring, but in most cases the water recharges the spoil aquifer and is more
slowly released at perennial discharge points. Also aiding surface water infiltration is the
characteristic high porosity of mine spoil, which permits rapid acceptance and storage of
relatively large quantities of ground water.
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Site Assessment - Backfill Testing
- i ' I
Spoil characteristics, such as hydraulic conductivity, porosity, and infiltration rates, are by-and-
ii ' , ,'n ' 'I , :
large dependent on site-specific conditions. Even with site-specific testing, these parameters can
I, ' : J
vary widely and are only predictable within a broad range. A wide range of hydraulic
conductivity values (up to 3 orders of magnitude) can be recorded within a single mine site
(Hawkins, 1998a). Prediction of these values prior to mining is exceedingly difficult.
Hawkins (1998a) conducted aquifer tests on several mine sites across the northern Appalachian
I
Plateau in an attempt to predict mine spoil hydraulic properties. He found that the best
correlation occurs between the age of the spoil and the hydraulic conductivity. The impacts of
' .. ' ' ;! ';; " " " . : ;',:, :. 1 , : : .'
other factors (e.g., lithology, spoil thickness, and mining types) on spoil properties appear to be
masked by a variety of factors introduced during the operation.
!
Given the broad range of mining types, spoil lithology and age, and other factors, it is doubtful a
narrowly defined prediction model will ever be available. In addition to the aforementioned
testing problems, spoil will at times exhibit turbulent flow which does not obeyDarcy's Law,
invalidating the aquifer testing procedures.
" , jj
Materials used in sealing or grouting may require analysis to ascertain their hydraulic properties,
, i""
and thus, determine suitability of use. Field testing for compaction or density may also be
needed. This testing can be performed via a standard penetration test, using a penetrometer.
1.1.1 Implementation Guidelines
There are very few, if any, situations where the proper implementation of the surface water
infiltration reduction BMPs discussed in this chapter will not have a positive impact toward the
reduction of pollution loads. A reduction of recharge ultimately reduces discharge rate, and
discharge and pollution load rates commonly exhibit a strong positive correlation. Therefore,
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with a reduction in flow rate, pollution loads usually exhibit a reduction commensurate with the
decreased flow (Hawkins, 1995b). Until the present, however, these BMPs have been
implemented almost entirely with the intention of aesthetically-pleasing reclamation in mind.
The prevention of surface water infiltration has not been a specifically targeted concern, thus the
true potential to reduce discharge rates with these BMPs has not been determined.
Regrading Abandoned Mine Spoil
A significant amount of surface-water infiltration can be reduced by regrading abandoned mine
spoil. Abandoned spoil piles commonly exhibit poor drainage. Closed-contour depressions and
poorly vegetated surfaces facilitate the direct infiltration of precipitation and other surface waters.
Closed-contour depressions permit the impounding of surface water which in turn promotes
infiltration into the spoil. Rough unreclaimed spoil ridges and valleys with exposed rock
fragments facilitate the direct and immediate infiltration of precipitation as it occurs. Removal of
closed contour depressions, elimination of spoil ridges and valleys, and the resulting creation of
runoff-inducing slopes greatly reduces surface-water infiltration into spoil.
Skousen and others (1997) observed an average flow rate reduction of 43 percent of a discharge
that averaged 188 gpm at a remining operation in Butler County, Pennsylvania. The main BMP
was regrading and reclamation of approximately 8.7 acres of abandoned surface mine land. A
second remining operation in Butler County, Pennsylvania reclaimed about 12 acres of
abandoned spoil as its primary BMP. Flow reduction of the discharges ranged from complete
elimination of one, 70 percent reduction of two others, and 25 percent reduction of a fourth.
While regrading and revegetation were not the exclusive BMP employed, these flow reductions
are indicative of what can be achieved with these BMPs.
Regrading of abandoned mine spoil is one of the most frequently employed BMPs in the
operation of remining permits. Older mining operations were not as efficient as present day
operations, and could not economically excavate as deeply as more modern equipment allows.
Regrading is an integral part of most remining permits. In order to achieve a minimum
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reclamation standard as statutorily mandated, abandoned spoil piles are regraded to return the site
I
to the approximate original contour or to at least achieve a more natural looking post-mining
" " ! ;.?' :'! ,l ' : . ' ' ' '!: r . ' . | i , , ", :.
condition. In order to maximize the efficiency of this BMP, the spoil should be regraded in a
" it' ' ',n I
The application of topsoil or an available soil substitute to newly regraded spoil improves the
ability of spoil to impede surface-water infiltration. Several factors that directly impact changes
ป, I ' ii : nl i
in the infiltration rate between bare spoil and top-soiled and revegetated spoil, are lithology of the
spoil material, composition, structure, roughness, and texture of the soil, density of vegetation,
and surface slope. Soil freshly replaced on spoil exhibits an infiltration rate that is considerably
'":' :,,, ' i " ' I ' i' , i
less than that for unmined areas (Rogowski and Pionke, 1984; Jorgensen and Gardner, 1987).
Therefore, it is not unexpected that the infiltration rate in resoiled spoil will be significantly
below that in unreclaimed spoil. These low infiltration rates are related to the lack of soil
* ii ? ' .'. ' ' ' :f I : , - :
structure, reduced root density, and the lack of other naturally occurring infiltration pathways that
are present in undisturbed soils. Over time, the infiltration rate of mine soils increase. However,
after four years, Jorgensen and Gardner (1987) observed that infiltration rates for mine soil were
still below natural soils. Potter and others (1988) noted that significant differences between
in:: : i: .1 " . ' ' ' ' . :" : . I , i
reclaimed soil properties and those of undisturbed soils still exist 11 years after reclamation.
'' , ' '!; . . '"' ' i!
Potter and others (1988) observed that the saturated hydraulic conductivity of reclaimed topsoil
1 ' - i
was approximately one fourth of that measured in undisturbed topsoil. Reclaimed subsoil
exhibited a hydraulic conductivity about a tenth of undisturbed subsoil. Silburn and Crow
,, ' ".,":' ...'., I
observed that subsoils composed of shale and clay spoils are 10 and 100 times less permeable
'in, ' .. ' i, ! . il . 'i
than from natural subsoils, respectively. Thus, runoff from reclaimed mine spoils is much greater
, ,. :; ; i, , , , ' , ti ;. , " ||< ,
than natural soils. The reasons for these differences are attributed to decreased percentage of
. . ./: ::'l ' ' ' ' :,,'!
large pores resulting in density increases, loss of soil structure and reduced depths to low
permeability layers (Silburn and Crow, 1984).
1-8
Hydrologic Controls
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Effective regrading of "dead" spoils, commonly an integral part of reclamation, will reduce the
amount of surface water that will infiltrate into the backfill. However, there may be situations
where site conditions indicate that re-affecting the spoil could cause an increase in the pollution
load. These are sites where the original mining was conducted several decades earlier, the spoil
has been naturally revegetated and the backfill is in a state of geochemical equilibrium. Re-
affecting the site would subaerially expose a significant portion of the backfill material, allowing
additional oxidation of pyritic material that was otherwise relatively stable. Remining (in this
case, regrading dead spoil) could reinvigorate the production of acid-mine drainage and cause
more problems than it abates. In these situations, the anticipated amount of reduced flow would
have to be weighed against the projected increase in contaminant concentration.
Installation of Surface Water Diversion Ditches
Diversion ditches can be constructed in two different locations, both of which reduce surface-
water infiltration into the backfill. First, diversion ditches can be constructed above the final
highwall or open pit to prevent surface water from adjacent unmined areas from entering the
reclaimed site and infiltrating into the subsurface. Second, diversion ditches can be constructed
within the backfill area to promote the efficient and rapid removal of direct precipitation prior to
infiltration into the spoil.
Diversion ditches can be installed on top of reclaimed mine spoil to control the rate and pathway
of runoff in the prevention of soil erosion. Diversion ditches also can be installed as part of a
BMP plan to reduce pollution load. These ditches should be constructed to collect as much
surface water as possible and to subsequently and expeditiously transport it from the site.
Properly constructed (lined and sloped) ditches installed on the backfill will transport runoff
from the backfill to the nearest drainage way.
A significant potential for recharge exists at the interface of the highwall and the spoil. For years
and probably for decades after backfilling, spoil tends to settle, compact, and undergo other
volume-reducing actions. While this settling occurs, the adjacent unmined highwall does not
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Coal Remjnfng BMP Guidance Manual
appreciably change. Because of this differential settling, it is common for linear surface gaps or
, ! /,. . I
cracks to run along or near this interface (Figure 1.1.la). These cracks create an ideal infiltration
. , ' " ii
zone for surface water. If surface water from unmined areas can be intercepted prior to flowing
.- , |
across a highwall and on to the spoil, a substantial amount of infiltration can be prevented. The
;; ,
i ' , ; i '- : , | ' . ,
installation of diversion ditches above the highwall is an effective BMP to preclude recharge to
l|i;!| ,, ' . I . ' ,;
the spoil from adjacent surface water runoff.
Figure 1.1.la: Diagram of the Location of Surface Cracks Between Highwall and Backfill
Linear Surface Cracks at the Buried Highwall
Surface Water"
Because of the transmissive characteristics of mine spoil, diversion ditches need to be lined or
sealed to preclude infiltration of the water that they are designed to collect and transport away.
Lining of these ditches can be performed using a variety of natural and man-made materials, such
, .., , ., . |
as existing on-site clays, bentonite, coal combustion wastes (CCW), sheet plastic or other
": ' ' ' ''. ' "' ' :,::" I' '
geotextiles, and cement (shotcrete). Regardless of the material used to line the ditches, it will
|
need to be durable. The integrity of these ditches should be maintained for a considerable length
of time or until the mine drainage discharges no longer exceed applicable effluent standards.
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By and large, there are very few situations where properly constructed diversion ditches will not
be beneficial in terms of reducing surface-water infiltration into the reclaimed site. Diversion
ditches constructed above the final highwall across undisturbed ground are unlikely to be
problematic in terms of leakage. The underlying subsoil and rock are less permeable than that
encountered in disturbed areas. Diversion ditches constructed across reclaimed spoil are more
prone to leak and allow substantial amounts of surface-water infiltration. The aforementioned
porous and permeable nature of spoil can facilitate rapid infiltration of significant amounts of
water over a short linear distance or at discrete points. Measures should be taken to insure the
integrity of these ditches. The emplacement of some type of ditch-lining material, natural or
manmade, is recommended. Where water velocities are sufficient to cause erosion, an erosion-
resistant material should be placed as a cover for the liner material.
Lining diversion ditches with a relatively impervious material reduces the amount of infiltration
through the bottom of the ditch, thus reducing recharge to the underlying strata. Reducing
recharge to areas adjacent to reclaimed mines can indirectly reduce the amount of recharge to the
mine spoil. When the adjacent strata receives increased recharge, some of this ground water will
flow toward and enter the spoil. Therefore, if surface-water infiltration from the diversion ditch is
impeded, recharge to adjacent spoil aquifers may also be reduced.
Low-Permeability Caps or Seals
There have been sporadic studies performed to determine the efficiency of sealing or capping the
surface of backfilled surface mines. The intention of sealing or capping is to preclude area-wide
surface-water infiltration by placing a low-permeability cap over the backfill material, before the
soil is replaced (Figure 1.1. Ib). Because of the large surface area to be covered and the generally
low profit margin at remining sites, the capping material should be readily available and
inexpensive to make this BMP a viable option. Capping materials generally should be composed
of a locally-available waste product, such as pozzolonic (self-cementing) CCW or a naturally-
occurring clay within a short hauling distance.
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Coal Retaining BMP Guidance Manual
Figure l.l.lb: Schematic Diagram of a Cap Installed on a Reclaimed
Surface Mine
Topsoil
Low-Permeability Cap
The installation of low-permeability caps over the top of mine backfills can be an effective BMP
i !'
for reducing surface-water infiltration. However, installation of these caps can be an expensive
i' ' '"iiij ' ' , ' , j ' !'
operation. Before approving the use of this BMP, the reviewer needs to ascertain whether it is
economically feasible. The reviewer also needs to determine that the capping materials are
readily available and of sufficient quality to complete the operation. Additionally, because mine
spoil continues to subside with time, as has been observed beyond ten years after reclamation,
the cap should be made to withstand the expected subsidence as much as possible.
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In order to prevent the movement of water and atmospheric oxygen, Broman and others (1991)
determined that capping materials need to have a hydraulic conductivity of 5 x 10'9 m/s or less.
Broman and others developed a mixture of 35 percent biosludge from a paper mill and 65 percent
coal fly ash. Lundgren and Lindahl (1991) specified a hydraulic conductivity of 1 x 10'9 m/s or
less for a capping material for waste rock piles in a copper-producing area of Sweden. They
successfully used a grouting cement-stabilized coal fly ash material, with a hydraulic
conductivity approximately one order of magnitude lower than this specified value. Hydraulic
conductivity values ranging from 10'10 to 10'12 m/s were recorded by Gerencher and others (1991)
for shotcrete used to cap and seal waste rock dumps in British Columbia. Based on these studies,
the hydraulic conductivity values necessary to create an effective cap are in the range of 10"9 to
10"1 m/s. These values are similar to values recorded for extremely impervious igneous rock,
such as dense unfractured basalt (Freeze and Cherry, 1979). Spoil, on the other hand, is
substantially more transmissive exhibiting a median hydraulic conductivity of 2.8 x 10'5 m/s.
However, the hydraulic conductivity of spoil exhibits a very broad range, 10"9 to 10'1 m/s,
depending on the parent rock lithology and other geologic- and mining-related factors (Hawkins,
1998a).
A 20 hectare mine site in Upshur County, West Virginia was covered with PVC sheeting in an
effort to reduce the pollution load. The result was a 50 to 70 percent reduction of the acidity load.
Even though additional BMP techniques (e.g., special handling, lime and phosphate addition)
were employed at this site and may have contributed some to the acid load reduction, the bulk of
the pollution load reduction appeared to be directly related to the subsequent flow reduction
(Meek, 1994).
A layered-composite soil cover was used to cover waste rock piles near Newcastle, New
Brunswick, Canada in an attempt to preclude infiltration of atmospheric oxygen as well as water.
The system consisted of a sand base overlain by compacted glacial till covered with sand and
gravel. The top layer of cover consisted of 10 cm of well-graded gravel to prevent erosion. This
system permitted between 1 and 2 percent of precipitation falling on the site to infiltrate into the
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Waste rock below the cap. The cap's low-permeability material was glacial till with a hydraulic
conductivity of 1.0 x ICX8 m/s (Bell and others, 1994).
Yanful and others (1994) constructed a cover for tailings piles in Canada to prevent the
infiltration of surface water and atmospheric oxygen. A 60 cm compacted clay layer was placed
between two 30 cm sand layers. The clay had an initial hydraulic conductivity of 1.0 x 10"9 m/s,
, ,:: ,! , j
Which did not change during the 3 year monitoring period. A thin gravel layer was placed over
the top of the cap for protection. This cover excluded over 96 percent of the total precipitation
from infiltrating into the tailings.
.;:' - ' ป! i i ป
* i ,1
These studies indicate that if a cap is placed on top of a reclaimed backfill, a significant reduction
pf surface-waterinfiltration can be achieved. For example, if a hypothetical unreclaimed and
unvegetated site permits infiltration of 75 percent of the precipitation (this number is likely
j
higher) and continues to allow 35 percent infiltration after it is regraded, the addition of an
'". '" , '' :: :' ' '.:- !' ;i ! " ' i.1
effective cap should decrease the infiltration rate to between 2 and 4 percent. Let us assume that a
100 acre site receives 40 inches of precipitation per year and all of the infiltrating water
discharges at one point. In the unreclaimed state, the average discharge rate would be 155 gpm.
Once regraded tne discharge will yield approximately 72.3 gpm. If a cap is installed the discharge
rate should be reduced to 8.3 to 12.4 gpm. If the initial acidity concentration is 120 mg/L, the
loading rate for the unreclaimed site would be 225.4 Ibs/day. However, with regrading and cap
=" ! , . ' :,: .ป!. ." v, l| , : i 1,
installation, even if the acidity concentration increased by 10 percent to 132 mg/L, acidity
loading would still show an overall decrease to a range of 13.3 to 19.8 Ibs/day or 91.2 to 94.1
1,' , ' . ' ', j .11
percent.
Revegetation
kevegetation of mine spoil can dramatically reduce the amount of surface water that would
j
otherwise eventually make it to the underlying ground-water system. Vegetative cover also can
decrease the amount of atmospheric oxygen that can enter the subsurface, because biological
activity in the soil, such as decay of organic matter, can create an oxygen sink. A well developed
... | i . _
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Coal Remining BMP Guidance Manual
soil with a dense cover of vegetation can retain a significant amount of water. Eventually, this
water evaporates or is transpired by the plants and does not recharge the spoil aquifer. Because
this BMP is a statutory requirement of all mining permits, it is one of the most frequently
employed. However, attempts to specifically tailor the vegetative cover to maximize
evapotranspiration are rare to nonexistent.
Evapotranspiration of surface water entering mine spoil will be enhanced as the vegetative cover
is increased (Strock, 1998). A thick forested area will permit more than twice as much
evapotranspiration (35 inches per year) as barren rocky ground (15 inches per year) in the same
area (Strock, 1998). The actual water loss depends on several factors including density, type of
plants, and length of the growing season.
Revegetation of a reclaimed mine will in most cases be beneficial toward reducing surface-water
infiltration. Caution should be used to prevent vegetative cover from providing conductive
avenues for surface-water infiltration. In some cases, the root systems of plants will create areas
where water can infiltrate in to the spoil. However, a lush vegetative growth may allow for
greatly increased evapotranspiration rates that can offset the increased infiltration along root
zones.
Stream Sealing
The sealing of streams reconstructed across backfill areas is intended to preclude direct
infiltration into the spoil. The increased permeability and porosity of spoil by comparison to
undisturbed strata promotes streams that have been reconstructed in mine spoil to lose water to
the underlying aquifer. The water table in surface mine spoil is commonly suppressed compared
to the water table at the site prior to mining and/or in adjacent unmined areas (Hawkins, 1995a).
A hydraulic gradient from the reconstructed stream to the suppressed underlying water table is
frequently present, thus facilitating infiltration. Therefore, reconstruction of these streams should
be conducted with the assumption that they will leak unless sealed or lined.
Hydrologic Controls 115
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Coal Remining BMP Guidance Manual
The primary and probably most inexpensive method of sealing streams is with plastic sheet
lining., Shotcrete can also be used for lining limited sections of stream beds in a relatively cost
effective manner. One of the problems associated with plastic lining is that the plastic sheeting
eventually breaks down chemically and ruptures or is punctured by sharp rock fragments.
Stream sealing also has been performed by excavating and emplacing a clay liner along the
i
stream reach (Ackman and others, 1989). In this case, the stream was disrupted by subsidence
from a shallow abandoned underground mine. The effectiveness of the clay seal was less than
100 percent. The section of stream that was clay lined exhibited a 4 percent loss of flow over
approximately 170 feet, whereas, the preceding section of stream exhibited an 8 percent flow
-:: : , j
decrease over a similar distance.
.'' :!,'.,! '! I : . '' '' i
'" ':&, ' , ' i .' .. I
Another method of stream sealing involves injecting polyurethane to grout targeted sections of
streams. Sirnilar grouting has been successfully conducted on losing streams situated over the top
of abandoned underground mine workings. In these cases, the underlying mine was relatively
jl,, J ,;,(;'! : , , i
shallow (25 to 50 feet) and losing stream sections were located by use of electromagnetic terrain
conductivity surveying equipment. Once located, zones of significant infiltration were targeted
for grouting (Ackman and Jones, 1988). Given the length of stream that would require grouting
and the high porosity of the spoil, it is doubtful that polyurethane grouting would be
economically viable for most remining operations.
Stream sealing as a BMP is appropriate only where a section of a stream is mined through and
!ป .,:,; i; , > : :r >". . I
subsequently reconstructed. Like diversion ditches that cross a reclaimed mine, these streams
should be rebuilt in such a manner that they do not leak water into the subsurface. The stream
" ' : 'ป'' , ,i! . I" :!i . , . i' ,. 'i1 , : I ;:
bed should be underlain with a liner material to preclude surface water infiltration. However,
erosion-resistant material should be placed over the top of the liner to prevent future liner
breaching.
1-16
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Design Criteria
The design and implementation plan of BMPs intended to reduce the infiltration of surface water
into mine spoil and adjacent undisturbed areas depends a great deal on site conditions (i.e.
amount of precipitation, location of surface water streams or drainage areas, original contour,
indigenous vegetation, soil type, and readily available materials. Recommended design criteria
for the implementation of surface-water infiltration control BMPs are included in the following
list. This list is by no means all-inclusive. Permit writers, regulatory authorities, and designers
should consider all site conditions with the intent of implementing the most cost effective means
of reducing pollutant loading during remining operations.
Regrading
Promote controlled runoff of precipitation and other surface waters
Return the site to the approximate original contour
Performed along the contour to minimize erosion and instability
Diversion Ditches
Divert runoff away from disturbed areas
Promote rapid runoff from disturbed areas
Adequate to pass the peak discharge of a defined storm event such as a 2-year, 24-hour
storm (temporary ditches) or a 10-year, 24-hour storm (permanent ditches)
Diversion ditch construction in landslide prone areas or where severe erosion is possible
should be performed with extreme care, if at all
Caps or Seals
Use readily available materials (e.g., on site clays or CCW)
Material with hydraulic conductivity of 10'9 m/s or less
Should be able to withstand anticipated subsidence without breaching
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Revegetatiop
H' ' ' ' V. ': , .. .' ; : ... , ,', i I)/'. , il
Root systems should retain water and not provide infiltration pathways
i Select local and native plant species that will thrive and create a lush cover
;4 : ซ' ' "' ' ' ''' ' '' ; ., : , : ii , ! ; ,i
Stream Sealing
Use chemically inert materials that are not prone to erosion or puncture damage
* Use readily available materials (e.g., on-site clays or CCW)
1.1.2 Verification of Success or Failure
* i'i1 ' liir ' ' ' 'I , I .. ! ' ' !'
i ] . ihi: ' ii|! ' '" : "" , ' ' ' :!' I " ! 'v:
Verification mat BMPs have been properly and completely implemented during remining
operations is crucial to effective control or remediation of pollutant loading. In other words,
monitoring should ensure that the as-built product is the same as that originally proposed by the
operator and approved by the regulating authority. The importance of field verification of all
1 ' ';' ' ' ? '" ,,;',', '' }"!' ' ' '
aspects of a BMP cannot be overstated. It is the role of the mine inspector to enforce the
' i in, . "',':iii' : ' ' . "(i-; '"'',:, I i1 . ' i .,
provisions outlined in the permit. The mine inspector does not need to be present at all times to
assess the amount of regrading for dead spoils, the elimination of closed-contour depressions or
revegetation. The completion of these tasks should be evident from visual inspection or if
required, from a survey of the area.
: is . ' , | " '
The actual installation of diversion ditches or stream replacements should be self evident from a
visual inspection. However, whether the ditch or stream was properly constructed and will not
leak requires a bit more work on the part of the mine inspector or hydrologist. If a liner was
prescribed for proper stream installation, the inspector can require weigh slips or receipts for
material brought into the site. If on-site material is to be used, a marked material stock pile can
be required. An inspector also can require notification of liner installation and completion dates.
Failure of a ditch or a stream to hold water can be determined by conducting flow measurements.
If the flow shows a significant decrease (e.g., outside the known error of the flow measurement
method) or disappears altogether, there is an indication that water is infiltrating and recharging
the backfilled site.
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Coal Remining BMP Guidance Manual
Determining the implementation level of some of the BMPs discussed in this chapter after the
fact is not always an easy procedure. Verification that a capping seal was installed properly,
without being present during the operation, can be difficult. However, if the capping material is
trucked in from an outside source, weigh slips or receipts can be obtained to confirm the amount
of material used. If on-site material is to be used, a marked stockpile of the material can be
required. Given the amount of work involved in spreading and compacting, it is likely a mine
inspector will visit the site at least once during the capping process. If there is great concern that
the cap will not be properly installed, the permit can be conditioned to require notification of the
mine inspector at predetermined salient points during the procedure.
The efficiencies of BMPs need to be monitored in order to improve and effect future refinements
of the processes. Not only does the type of BMP need to be assessed, but the scope and degree of
BMP implementation needs to be related to the degree of improvement (e.g., flow or pollution
load reduction). The mechanism to determine the effectiveness of BMPs discussed in this chapter
is similar to any abatement procedure research project. In the case of these surface water control
BMPs, a significant portion of the monitoring will consist of measuring the flow rates of
discharges emanating from the site. It is fully realized that the locations of discharges may, and
frequently do, move from their pre-remining locations. Therefore, a hydrologic-unit approach is
recommended. The mine site should be divided into hydrologic units, that is, portions of the mine
that contribute to one or more discharges. Discharge data (flow and/or loading rate) can be
mathematically combined to permit pre- versus post-mining comparisons.
Given the nature of mine spoil and the time that it takes for a water table to re-establish and reach
equilibrium, post-mining monitoring may need to continue for at least 3 to 5 years. In eastern
Ohio, water-table re-establishment at three reclaimed surface mines was observed to be nearly
complete approximately 22 months after reclamation was completed (Helgesen and Razem,
1980). Recovery of the water table after mining may take 24 months or longer in Pennsylvania
(Hawkins, 1998b). The rate of water-table recovery is related to several factors including
precipitation, infiltration and discharge rates, porosity, topography, and geologic structure.
Additionally, short-term changes in flow and/or contaminant concentration commonly occur
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j
*ฃoal Returning BMP Guidance Manual
during the initial 1-3 years after backfilling because of substantial physical and chemical flux
Within the spoil aquifer. During this period, the water table is re-establishing and the spoil is
undergoing considerable subsidence, piping, and shifting. Sulfate salts, created by oxidation
when cast overburden is exposed to the atmosphere during mining, are flushed through the
system (Hawkins, 1995b). It is important to monitor these sites beyond the initial re-
establishment period, in order to accurately assess the true changes due to remining and BMP
implementation. The length of the post-mining monitoring period may vary from site to site
" ,ซ ,, i , " ij
depending on climatic (e.g., precipitation) and hydrogeologic (spoil porosity and permeability,
!'!": ' '(' f' ', ' ' "...,, ;, " 'V... ''..I'.1
topography, etc.^ conditions, and should be at the discretion of the professional in charge of
project oversight.
Implementation Checklist
Monitoring and inspection of BMPs, in order to verify appropriate conditions and
Implementation^ should be a requirement of any remining operation. Though BMP effectiveness
is highly site- specific, it is recommended that implementation inspections of hydraulic control
BMPs include me following: .
Measurement of flow and sampling for contaminant concentrations (before, during, and
after mining)
Jvlonitor|ng should continue well beyond initial water table re-establishment period (e.g.,
about 2 years after backfilling)
Assessment of hydrologically connected units as well as individual discharges
Review or inspection ofDealing-material weigh slips, receipts, or marked stockpiles
!"! ' ii : - , '' .' -, .1 (
Review of implementation initiation and completion dates
1 " .': , ! - .- llf' , ! :
Assessment of any deviation from an approved implementation plan
Inspection of salient phases of the BMP implementation
Inspection of diversion ditches, caps and seals for leakage
' . /.i ; .'. j
Inspection of vegetation for viability
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Coal Remining BMP Guidance Manual
1.1.3 Case Studies
Presented below are results from three completed remining operations for which a significant
portion of the site had dead spoils regraded, closed-contour depressions eliminated, and more
natural runoff-inducing slopes created. It is important to note that the full potential of these
BMPs may not have been realized because regrading was performed primarily as part of the
perfunctory reclamation process. These BMPs were not necessarily implemented with the
minimization of surface-water infiltration as a primary intention. Evaluation of these sites may
tend to underestimate the potential for infiltration reduction that can be achieved. Minor
implementation modifications can dramatically affect efficiency. Future efforts which employ
these BMPs to their greatest potential should be closely monitored and analyzed in an attempt to
ascertain true BMP efficacy and to develop methods for fine tuning and improvement.
There are several factors that make pre-mining versus post-mining comparison difficult. One of
the main pitfalls in comparing the discharge rates is the assumption that the pre- and post-mining
periods have had similar precipitation preceding the measurements. Precipitation amount,
duration, and intensity can vary widely from event to event, season to season, and year to year,
serving to complicate pre- to post-mining comparisons. This is especially true when the sampling
periods before and/or after mining are relatively short (e.g., a year or less). Another complicating
factor is that post-mining sampling often will include a period of time when the water table is re-
establishing and much of the infiltrating water is going into storage. Under ideal conditions, an
evaluation of flow reduction from BMPs discussed in this chapter would entail similar climatic
conditions, preclude data collected during water table re-establishment, and include several years
of pre- and post-mining monitoring. These criteria are seldom met in real-world situations. The
location of the pre-existing discharges commonly move because of the physical disruption of the
yielding aquifer and ground-water flow paths, and the change of the flow system from a fracture-
flow dominated system to a dual-porosity system as exhibited in mine spoil. These caveats and
potential problems should be considered while reviewing the case studies below.
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Coal Remining BMP Guidance Manual
Case Study 1 (Appendix A, EPA Remining Database, 1999, PA(6))
1(1 ''. 'I! " i " I ' ,
', ' ' 'il . I ' " J
'i . ( | :
This mine was located in Armstrong County, Pennsylvania where the renaming was performed on
: ;; ' ' '.'. '" I . "' N
abandoned surface mines in the Upper Freeport and Lower Kittanning coal seams. All 24.8 acres
of abandoned surface mined land within the permit boundary was reclaimed by the operation.
'! ; ' ' ' '!'", '..;,!| / ' . " i " ' : ; if; . ;. |. , {; .(,i
According to the permit application, the total area to be affected by mining operations was 126.5
acres. The operation also eliminated 1,700 feet out of a possible 2,600 feet of highwall.
t " '; ;>*! '' .. '. , '&! . I i, _ i "i
Originally, two remining discharge points were included in the permit. However, a third
discharge point was added later. The BMPs listed in the permit included regrading of abandoned
mine spoil (24.8 acres), underground mine daylighting (5 acres), special handling of acid-forming
materials, and revegetation. The most predominant BMP component by far was the regrading.
The site was completed in August of 1996 and post-mining water quality data has been collected
since. A synopsis of the data is shown in Table 1.1.3a.
The changes in flow rates from remining of this site are somewhat inconsistent. Discharge point
MD-2 exhibits a statistically significant increase in flow, but the acidity and iron loads are not
significantly higher. This is caused by decreases in concentrations and a relatively broad range of
values, resulting in a wide 95 percent confidence interval about the median, as is commonly
associated with mine drainage. Discharge points C-3A and C-17A exhibit only very minor
differences in the discharge rate after remining. The acidity concentration decreases caused the
ปป' i , iiii , ij i i
median acidity loads to be substantially lower, but only the decrease in the median acidity load of
C-17A is statistically significant.
13: i
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Coal Remining BMP Guidance Manual
Table 1.1.3a: Synopsis of Water Quality Data at Case Study 1 Site
Parameter
Sample Number (n)
How (gpm)
Acidity Load (Ibs/day)
Iron Load (Ibs/day)
SulfateLoad (Ibs/day)
Discharge Points
MD-2
Pre-Remining
22
2.4
1.93
0.0016
5.57
Post-Remining
22
27.1
4.76
0.0044
85.78
C-3A
Pre-Remining
24
14.2
16.17
0.09
23.15
Post-Remining
22
16.3
0.75
0.10
60.01
C-17A
Pre-Remining
6
12.5
8.56
0.003
21.06
Post-Remining
17
9.1
0.07
0.003
25.45
All numbers are median values.
The lack of better flow reduction may predominantly be due to precipitation differences during
the two comparison periods and, to a lesser degree, to a rerouting of ground-water flow paths.
The reclamation area comprised a small amount (slightly under 20 percent) of the total area to be
disturbed by remining. In addition, the post-remining period is relatively short (less than 2 years)
in terms of allowing complete re-establishment of the water table and post-remining stabilization
of the entire hydrogeologic system. Additional monitoring of the site will likely illustrate more
clearly the true impacts of regrading and revegetation.
Case Study 2 (Appendix A, EPA Remining Database, 1999, PA(7))
This mine was located in Clearfield County, Pennsylvania. Remining was performed on
abandoned surface mines in the Upper Freeport and Lower Kittanning coal seams. Ten acres (32
percent) of the 30.8 acres of abandoned surface-mined land within the permit boundary was
reclaimed by the operation. Of the 101.1 acres of abandoned underground mines on the Lower
Freeport coal, 17.3 acres (17 percent) were daylighted during the remining operation. According
to the permit application, the total area to be affected was 139.3 acres. Two remining discharge
points were included in the permit. The BMPs listed in the permit included regrading of
abandoned mine spoil (10 acres), underground mine daylighting (17.3 acres), sealing of exposed
mine entries, special handling of toxic materials, and revegetation. The predominant BMP
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Coal Remining BMP Guidance Manual
components were regrading, revegetation, and daylighting. The site was completed in May of
1996, and was assessed using monthly water-quality data collected through August 1997. A
f , ! Ill '' Ilillll1 ' !l ' , . || i''
synopsis of the data is shown in Table 1.1.3b.
i' i : ' ": f i ., , .; . ' |
Table 1.1.3b: Synopsis of Water Quality Data at Case Study 2 Site
Parameter
Sample Number (n)
Flow (gpm)
Acidity Load (Ibs/day)
Iron Load (Ibs/day)
SulfateLoad (Ibs/day)
Discharge Points
MD-12
Pre-Remining
44
0.55
2.48
0.047
2.87
Post-Remining
16
0.40
0.59
0.006
2.65
MD-13
Pre-Remining
47
31.6
176.2
9.99
273.79
Post-Remining
16
35.9
133.7
6.31
289.8
All numbers are median values.
Analysis of the data indicate that the flow rates of the two discharges were not significantly
changed by the remining (regrading and revegetation); there is no statistical difference. The
*'''!' !. i;i'' ^1' I , ' : :' ' !," ' 1" ." ' ' I , '.
acidity and iron concentrations at MD-12 were significantly reduced, but the lack of significant
,;. ' ! ' " " , . ,. I' '' : '. '"
flow changes prevented concomitant acidity and iron load reductions. Figures 1.1.3a and 1.1.3b
illustrate an example of these observations. The lack of overlap of the notches indicating the 95
percent confidence intervals about the medians indicate that the medians of acidity data before
1, -,. , ::;;,*:: " . , ; , .". , . , .j ' . ... ' v.
and after remining operations are significantly different, with a definitive decrease in acidity
following remining site closure.
I,-'*
1-24
Hydrologic Controls
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Coal Remining BMP Guidance Manual
Figure l.l.Sa: Acidity Concentration at Discharge Point MD-12 Before and After
Remining
MD-12
800
Pre-Remining Post-Remining
Acidity
Figure 1.1.3b: Acidity Load at Discharge Point MD-12 Before and After Remining
30
MD-12
Pre-Remining Post-Remining
Acidity Load
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Goal Remining BMP Guidance Manual
"In, | , ,h I .1 ป , , ' ' ' !
I1- , ; >:,. *! T ,. ' ' :: ,. 1[ ., - >ป>
Some of the same caveats that apply to Case Study 1 also apply to this site. The climatic
differences (e.g.^ precipitation) for the two sampling periods should be considered as part of the
overall evaluation of flow changes due to remining. For example, the period of pre-remining
sampling (12/86 through 9/89) averaged 2.83 inches of precipitation per month, while the post-
remining period (5/96 through 8/97) averaged 3.36 inches of precipitation per month. This is an
increase of about 19 percent. The precipitation values were compiled from the Pittsburgh
International Airport which is approximately 90 miles southwest of the site. However, the data
can be used for the general precipitation trends during pre- and post-remining sampling periods at
this site. The increase in flow from the combined discharges (about 13 percent) is not
'I' '.' '"' . " ,|| '' "jjjr i. " ,.. :1'" ,, t " ป ''' .. '"'' i '"'.i'"'1 "" ',',' I ' . i1"1'''" ','.,, i
commensurate with the recorded precipitation increase. Additionally, the post-remining period is
i|niซ ii'i ' ' " ,,!!!J"'!"'!' il.,, I ' " i , iป - , ,. " WJin ' i| ' ... . . , ". ,,i
relatively short (less than 2 years) in terms of allowing complete re-establishment of the water
table and post-remining stabilization of the entire hydrogeologic system. Additional monitoring
:;"' "..', :ซ . . , " , ; . I : -, ; . i
of the site over a longer time period and with similar precipitation amounts will likely clarify the
true impacts of regrading and revegetation.
Case Study 3 (Appendix A, EPA Remining Database, 1999, PA(10))
This site is located in Somerset County, Pennsylvania. Remining was conducted on the Lower
JBakerstown coal seam. According to the permit application, a total of 85.8 acres was to be
affected by the operation and 48.8 acres of coal removed. BMPs employed at this site included
"'", : I' ' liilll " , " ' ' "3 JIlL '' '' 1| ', ! '
regrading of abandoned spoils, alkaline addition, hydrologic controls, revegetation, and
scarification of the calcareous pavement (seat rock). Of the 32.2 acres of abandoned mine lands
within the permit boundary, 15.6 acres, or 48 percent, were to be reclaimed. Approximately
1,800 feet (84 percent) of a total of 2,150 feet of abandoned highwall was eliminated. The
'"' : ' :'! "I"!,! :" ' , , " ' " ; ! " '' '
alkaline addition rate was 3 tons per acre applied at the interface of the spoil and the topsoil.
Hydrologic controls consisted of a clay barrier placed between remining operations and adjacent
.ซ ': ' ' ,..,,., jl ,
Unreclaimed areas. The seat rock was found to be alkaline and was scarified to increase the
surface area of the alkaline material exposed to ground water. Reclamation was completed by
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Coal Remining BMP Guidance Manual
November of 1995 and monitoring has continued since that time. Table l.l.Sc is a synopsis of
the flow and loading data for this site.
Table 1.1.3c: Synopsis of Flow and Pollutant Loading Data at Case Study 3 Site
Parameter
Sample Number (n)
Flow (gpm)
Acidity Load (Ibs/day)
Iron Load (Ibs/day)
Sulfate Load (Ibs/day)
SP-10
Pre-Remining
8
7.47
2.72
0.006
21.6
bo
c
"c
1
1
34
5.15
8.18
0.008
49.4
Discharge Points
SP-11
Pre-Remining
8
11.3
20.5
0.03
71.1
g,
"c
5
ฐr
to
S.
34
3.0
7.4
0.01
57.2
SP12
Pre-Remining
8
1.0
1.04
0.004
11.3
All numbers are median values.
Post-Remining
34
0.7
0.95
0.003
6.06
SP-18
Pre-Remining
8
0.88
0.31
0.003
3.04
Post-Remining
35
1.20
1.97
0.004
9.51
SP-23
bO
c:
[S
'5
o>
CZ
2
cu
4
0
0
0
0
bo
c
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'5
3
c:
ts
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34
0
0
0
0
This site exhibited an accumulative discharge median flow reduction of 10.6 gpm or slightly over
51 percent. However, only SP-11 exhibited a statistically significant flow reduction on an
individual basis. According to the precipitation history from the Pittsburgh International Airport,
precipitation during the two sampling periods was dissimilar, with precipitation during the post-
remining period (a mean of 3.29 inches per month) being about 15 percent below the background
sampling period (a mean of 3.85 inches per month). Roughly 15 percent of the flow reduction
may be attributable to reduced precipitation, but the remainder appears to be related to regrading,
highwall elimination, and revegetation. The same caveats discussed in Cases 1 and 2, on using
precipitation data from a site somewhat removed from the actual mine sites, apply here. These
results illustrate that substantial flow reduction (approximately 35 percent) may be realized by a
50 percent reduction in abandoned mine lands, even with additional mining of virgin areas (49
acres) occurring in conjunction with the operation. The post-mining monitoring period is
considerable, exceeding three years, but additional monitoring is required to determine whether
the trends observed are genuine and can be expected to continue. Additional flow reduction may
Hydrologic Controls
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Coal Remining BMP Guidance Manual
be possible if regrading and revegetation are designed specifically with the intent of preventing
surface-water infiltration, rather than solely with the intent of returning the site to an
j't '"' ''ij : '. - .(. i .: ..' .'',: : '.i i ' , , |
aestheticaliy-pieasing approximation of the original pre-mining contours and conditions. Specific
Operations to reduce surface-water infiltration may include, but are not limited to, additional
compaction of the spoil to reduce permeability, final slopes that may differ from the approximate
Original contour but are more efficient in promoting runoff, and plants that promote runoff and/or
;: "ป " ' ' " - '* ' ' I ' .
utilize substantial amounts of the water that does manage to infiltrate into the soil horizon.
' ' ' ' "'
Even with the aforementioned reductions in discharge flow, two of the discharges (SP-10 and
SP-18) exhibited a statistically significant increase in median acidity and sulfate loads. This
V , ,. I |i i'lfii' . , . '. ..''.' ,,;.;>' . . ;' || i , , , V I ! .
difference is caused by substantially higher acidity and sulfate concentrations after reclamation.
Discharge points SP-11 and SP-12 also exhibit significantly increased concentrations of acidity,
but the reduced flows prevent the median loadings from being significantly different from the
baseline levels. This indicates that the site may be producing more acidity, but the reduced flow
moving through the site has prevented the combined discharge acid load from exceeding
!"' i . ,' ' ,j|' ij :'" '''..j . : i ' 'u i ; !,' '' ,' ',' !' ' , : , j :, ' i" ' ' llli ,
baseline. Geochemical conditions within this reclaimed operation have worsened, or become
, , , ... .. , i
more acidic. The causes of this possible failure will be discussed in detail in the section on
alkaline addition.
To obtain a more definitive determination of the efficiency of regrading and revegetation to
reduce discharge rates, additional studies are needed on sites where these BMPs are employed
specifically to preclude surface-water infiltration. The case sites discussed above utilized these
BMPs during repining operations, but they did not specifically design or implement them to
minimize infiltration of surface water. Thorough evaluation of these studies also requires site
i
specific precipitation data for background sampling as well as post-mining sampling periods. A
. ' . i' : . i - . l _
sufficient post-mining sampling period of at least 3-5 years, depending on climatic and site-
" : ' " ri ' ' " I"
specific conditions, is required to permit a true assessment of BMP efficiency. With these data,
i ., ']: "i! . : -;. . , ., - . f .1 , ?> ] , . , ' ;
prediction of load reduction based on the amount of regrading, re vegetating, and other BMPs
ii;!:1'1 ' ' '''" "!" '' ' " ', . '! ' i .. , i"" j|i !' '
may be possible.
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1.1.4 Discussion
The BMPs discussed in this chapter, when properly employed under the right conditions, will
successfully reduce the infiltration of surface waters and should subsequently reduce the
discharge yield. However, these BMPs cannot be viewed as a panacea for all pre-existing
problems at a site. There are limits to what can be physically achieved and/or economically
attempted. The two lists below (Benefits and Limitations) include, but are not limited to, what
can and cannot be expected of these BMPs.
Benefite
Reduces pollution loading from abandoned mine land
Establishes a hydrologic balance to site
Restores land to approximate original contour and creates an aesthetically pleasing post-
remining configuration
Requires little additional cost to the operation because they are often already implemented
as a statutory requirement during remining operations
Limitations
Current implementation of hydraulic control BMPs focuses primarily on reclamation. A
complete evaluation of the effectiveness for pollution prevention, in terms of reducing the
discharge rate, is needed.
Careful consideration should be made to the implementation of surface-water control
BMPs in areas abandoned for long periods or with some degree of natural remediation
(e.g. stabilized spoil, natural vegetative cover).
Complete exclusion of infiltrating surface waters is not likely, therefore the discharges
will not be entirely eliminated.
Efficiency
Analysis of completed remining sites in Pennsylvania (Appendix B, PA Remining Site Study)
indicated that at sites with regrading as a BMP, 46.1 percent of 154 discharges were eliminated
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Coal Remining BMP Guidance Manual
or were significantly improved in terms of acidity loadings. Over half the discharges (53.2
percent) were unchanged and less than one percent (0.6 percent) were significantly degraded with
respect to acidity loadings.
For iron loadings, 42.3 percent of 137 discharges were eliminated or significantly improved from
remining. Over half (52.6 percent) of the discharges were unchanged, while 5.1 percent showed
significant degradation for iron loadings.
...... ' |
The manganese loadings for 39.6 percent of the 1 1 1 discharges were significantly improved or
if > V i!!!l jj ' ,:' ' . ' '>.' i; :' '. :" ! '
eliminated, while 52.3 percent were unchanged. The manganese loading failure rate was the
highest for the parameters analyzed, with 8.1 percent significantly degraded. This has been a
(' ...... (?,'. , ' , . , : : - i f | ....... , , , i
common trend for all the BMPs. Manganese loadings exhibited the highest failure rate (9.0
percent for 155 discharges) regardless of the BMP employed.
'! : } . :
, " , " ' ' ' ;l| ' ' ? . " ' " '' ' '.:
The bulk (60.7 percent) of the aluminum loadings for 84 discharges were unchanged, while 36.9
|';1 ......... ' > ; '";,| ..... , , ., ..... ' ; i ;! <' " 'I
percent of the discharges were significantly improved or eliminated. Discharges that were
Significantly degraded, in regards to aluminum loadings, amounted to 2.4 percent.
1 ' ' '
it
.... /;
1.1.5 Summary
Studies have shown that the extent of pollution reduction from remining is largely dependent on
reducing the discharge rate, which in turn is dependent on controlling the infiltration of surface
water into the backfill. The commonly-observed positive correlation between flow and loading
rates illustrates the close relationship between the two. BMPs that are designed and implemented
to prevent surface-water infiltration will be successful in reducing the pollution load.
,ซ ' ,,'i ' ,'T",i . , ' j| . : , " I ,
The case studies above illustrate that regrading and revegetating can yield mixed results unless
differences in precipitation rates are taken into account and the post-mining monitoring period is
of sufficient length to accurately reflect site conditions. However, it is well known that these
I
BMPs, when properly implemented, will reduce the contaminant load from remitting operations.
ii ,
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1.2 Control of Infiltrating Ground Water
Methods to control the lateral infiltration (recharge) of ground water into remining sites from
adjacent mines and undisturbed strata include, but are not limited to, daylighting of underground
mine workings, sealing exposed mine entries, auger holes, highwalls and pit floors, and installing
diversion drains, vertical highwall (chimney) drains, pit-floor drains, grout curtains and diversion
wells. These BMPs are designed to work in one of two ways to reduce the ultimate discharge
flow rate: (1) to preclude or-divert the lateral movement of ground water; and (2) to intercept and
collect laterally-migrating ground water and channel it away from the backfilled areas. These
BMPs are effective singly or when used in conjunction with others, but are seldom used alone
during remining operations.
Currently, these BMPs are being used as a part of the general mining and reclamation processes,
but they are not being implemented with ground-water handling as the primary concern.
Therefore, the results of the case studies (discussed below) and other remining data (Appendix B:
Pennsylvania Remining Site Study) may tend to underestimate the potential for lateral infiltration
reduction that can be achieved. Minor implementation modifications toward ground-water
handling can dramatically effect the efficiency of these BMPs with little additional time or
expense introduced.
Theory
Ground-water modeling of reclaimed surface mines has shown that a substantial portion of
ground-water infiltration into mine spoil comes from adjacent areas. Infiltration from adjacent
areas can originate from other surface mines as well as from unmined strata. The nature of this
lateral recharge can be continuous or episodic. Adjacent areas tend to permit lateral ground-
water movement somewhat continuously under baseflow conditions, long after the last
precipitation event. However, rapid, high-volume lateral recharge also can occur immediately
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following significant rainfall events (Hawkins and Aljoe, 1990). Fractures in the adjacent strata
ii:1'.;1 '' '<> ,.,'i. : , i ,, j , | , . i . , , i1
can yield substantial amounts of water during or shortly after significant precipitation. The
BMPs discussed in this section need to be able to accommodate this bimodal, lateral ground-
water infiltration.
XJnlike many of the BMPs implemented to prevent surface-water infiltration, most of the BMPs
for preventing lateral ground-water movement are implemented on and above standard
: ' 'K ' ft . , i , . ' , :,';.(. . |,
reclamation practices. These BMPs tend to be more labor and material intensive than standard
: ,. ': MJJ - 'i ' '. ".'' ' " :'; v >;!!: ,::; ' 1 :"
reclamation practices, and therefore, can be more costly. One exception is underground mine
daylighting, which is performed as a consequence of the remining process. However, the time
and effort required to clean the waste rock from around the remaining coal pillars entails
^ , '.,, . , . . i, - ,,
additional cost during mining, the percentage of coal recovery is less than that for virgin areas,
and additional acid-forming materials should be special handled. Some of the BMPs discussed
; " _ |j;; ,;;ซ < | ' . ;> . ;(;'
in this section are mandated by regulation, such as sealing of auger holes and exposed mine
i
entries.
The effectiveness of many of the ground-water control BMPs relies largely on the use of proper
engineering techniques. As with BMPs implemented for the prevention of surface-water
i i'. : ;i ' ' :.r. ' " , i '; ' , :.;,; . ', I t" "< <
infiltration, there are very few situations where these BMPs will fail. If the ultimate discharge
flow rate is reduced through reduced lateral infiltration, there is a high probability that the
,(! ,, - ' ; ; ' ,.l,| . . '! :or , .. ... i ,: ' , ; .. . .
pollution load will be diminished. Figure 1.2a shows the strong flow-versus-pollution-load
1 , " ' ' . ",',!' li rv I,;,,
correlation commonly exhibited by mine drainage discharges. There are hydrogeologic
, ,,,,,!,,
conditions where some of these BMPs could exacerbate the production of acid mine drainage
. ' ,.,! , ,,,!' ' , '" , , j
(AMD). In these cases, the BMP should be eliminated or modified to prevent additional
pollution. In situations where the BMP is an integral part of the entire operation (e.g.,
day lighting), additional BMPs will need to be added or designed to compensate for possible
deleterious side effects of the others.
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Figure 1.2a: Typical Correlation Between Discharge Flow and Pollutant Loading in Mine
Drainage Discharges (Appendix A, EPA Remining Database, 1999 PA(6),
MP-A)
400
300
200
100
0
o
I-J
10
20 30
Flow
40
Site Assessment
Assessment of spoil characteristics is site-specific for each operation. Even with on-site testing,
spoil hydraulic parameters can be highly variable. Hawkins (1998a) observed that hydraulic
conductivity can range widely (up to 3 orders of magnitude) within a site. This makes prediction
of spoil characteristics prior to mining extremely difficult. However, there are some general
conclusions that can be drawn about mine spoil.
Hawkins (1998a) conducted aquifer tests on several mine sites across the northern Appalachian
Plateau in an attempt to predict mine spoil hydraulic properties. He found that the best
correlation occurs between the hydraulic conductivity and age of the spoil. The impacts of other
factors (e.g., lithology, spoil thickness, and mining type) on spoil properties appear to be masked
by a variety of factors introduced during the operation.
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Given the broad range of mining types, spoil lithology and age, and other factors, it is doubtful a
narrowly-defined prediction model will be available. In addition to the aforementioned testing
problems, spoil will at times exhibit turbulent flow which does not conform to Darcy's Law and
causes aquifer-testing procedures to become inapplicable.
Prior to the engineering and installation of highwall and pit floor drains, an assessment as to the
amount of ground water to be collected and piped needs to be made. This determination can be
performed by empirical testing of observed recharge while the pit is open or can be performed by
conducting a hydrologic budget exercise. The hydrologic budget will require, at a minimum,
knowledge of the size of the recharge zone, precipitation and evapotranspiration rates, storage
capacity, and aqliifer characteristics.
f
Si1:!1'!1' i" ' !' h. . In! ' i '! , ' , ',"'! i inn ' ' , ,!.,.', i
Materials used in sealing or grouting may require analysis to ascertain the hydraulic properties,
and thus, the suitability of use. Field testing for compaction also may be necessary. This testing
caii be performed via a standard penetration test, using a penetrometer.
Assessment of ground-water diversion (interceptor) wells may require aquifer testing. Performing
ifY ' '*'" 'V '"* ' . '!'', , . i ' ' "' ' "' ' f, , ;' ' 'f;' '' ':, ' " 1"
a constant-discharge test while monitoring other wells will yield insight as to the efficiency of
these wells Aquifer testing will also yield data on well and aquifer interconnection.
1.2.1 Implementation Guidelines
. ,
Daylighting of Underground Mines
ill!, if
'.'.!!' i,:'
Underground mining has been conducted in some areas of the United States for over 200 years.
Although limited surface mining was conducted in the early part of the 20th century, surface
mining did not become prominent until after the Second World War. Surface mining into higher
cover coal (greater than 30 to 40 feet) only became commonplace in the 1960's with the
I ','.... , , ... ;i
proliferation of mining equipment capable of moving large amounts of rock efficiently. Early
underground mining operations have left a considerable amount of abandoned underground
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Coal Remining BMP Guidance Manual
mines that are now candidates for renaming. These underground mines have been producing
untreated mine drainage since abandonment and, if left unchecked, will continue to do so for
decades or even longer. Daylighting of abandoned underground mines is one of the more
frequently employed BMPs during remining operations.
Daylighting operations are often economically marginal. This is because the same volume of
overburden associated with virgin coal needs to be removed, but the coal recovery rates are
greatly diminished. A coal recovery rate of 50 percent is usually the maximum observed at
daylighting operations, but this level is seldom achieved. Recovery rates are more commonly in
the range of 20 to 35 percent, because many of the mines were retreat mined (high coal
extraction from partially mining through pillars as the operation withdraws from the mine) prior
to abandonment. Because of this reduced recovery, the thickness of overburden that can be
removed economically is less than that for solid coal areas.
The act of daylighting is the removal of the strata above the coal (overburden), the removal of the
collapsed rock (gob) around the existing pillars, and the loading out of the coal. Once the coal is
removed, the site is reclaimed. Daylighting works to reduce lateral ground-water infiltration in
several ways. Abandoned underground mines are recharged, to a large degree, from fractures in
the overlying rock. The fractures are created primarily by stress relief of erosional rock mass
removal and to a lesser extent by tectonic (mountain building) activities (Wyrick and Borchers,
1981). One of the more prominent results of daylighting is that avenues for vertical recharge are
eliminated, and water that once recharged the underground mine is no longer available.
Daylighting of approximately one half a 380 acre abandoned mine in Allegheny County,
Pennsylvania reduced the flow by about 50 percent (Skousen and others, 1997).
Subsidence and collapse of abandoned mine workings can create additional fractures and
increase the size of existing fractures, also increasing their transmissive properties. Evidence of
subsidence is frequently observed at the surface as cracks, damage to surface structures (e.g.,
house foundations, roads, and utilities), and sinkholes (closed contour depressions).
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' '!!i;iiii!1
' in,,: i11 i in,.
Figure 1.2.la is a photograph illustrating exposed fractures accentuated due to mine subsidence.
i !'. "! , 'i.lt i"~~ "III , ' '"i'i ' :' ' ' ' . !,',; i . j i'"1 ; :, i" f T-JI'I
i'i I- " : ,*') " i,""I"ill '" ., , ; i ,\ ," ' . , 'I'li'i! ' , , I '"ซ, ' ,',;':, I"*ill
The degree of surface disturbance depends to a large extent on the thickness and lithology of the
overburden and the size of the mine void. Daylighting removes the highly transmissive avenues
for ground water to enter underground mine workings. Even when the underground mine has not
been completely eliminated, daylighting can dramatically reduce this recharge. Empirical
observations indicate that there is an exponential decrease in recharge to underground mines with
increasing overburden thickness. Shallow cover areas tend to yield more water to the mines than
deeper (thicker) cover areas and are more commonly eliminated through remining. In shallow
l^j'j N I ,'i, ป ' Ijfl , '' ' , ,,i ' ': '" , I, !i '.I ' ' ' ' ' ' ' 'il !' I ill'' '
overburden, stress-relief fractures are more frequent and generally more transmissive than in
deeper overburden (Borchers and Wyrick, 1981; Hawkins and others, 1996). Because of more
extensive fracturing with shallow cover, the overlying rocks are more susceptible to the impacts
from mine subsidence. For example, daylighting 20 percent of a mine, which is the shallowest
cover, will likely reduce infiltration by an amount much greater than 20 percent.
Figure 1.2.1a:
Example of Mine Subsidence and Exposed Fractures
' I Ill II
The storage capacity of underground mines is considerable, and can approach 65 percent of the
original coal volume. However, a storage capacity of 20-40 percent is more likely. A 100-acre
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Coal Remining BMP Guidance Manual
underground mine with 50 percent of the coal mined, a 5 foot thick coal seam, and no significant
subsidence has a potential storage volume of over 81 million gallons. If the mine workings are
only one third flooded, the mine water stored exceeds 27 million gallons. Storage of vast
amounts of mine water in underground mines allows for continuous lateral recharge to adjacent
operations, even during dry periods. Daylighting decreases the amount of storage available for
ground water and therefore prevents lateral movement into adjacent areas.
Abandoned underground mines are commonly ideal environments for AMD formation. If acidic,
metal-laden ground water is infiltrating into an adjacent surface renaming operation, it can cause
the formation of more AMD than the sum the two mines would produce separately. For
example, it is known that ferric iron (Fe3+), a product of acid-mine drainage formation, can
become the main oxidant of pyrite. Additional pyrite oxidation can occur even under suboxic or
anoxic conditions (Caruccio and Geidel, 1986). Therefore, AMD entering into pyritic-rich zones
in spoil can produce more pollution than the spoil would produce on its own.
By and large, the water quality of underground mines is much poorer than that of surface mines
on the same seams (Hawkins, 1995b). AMD formation is facilitated by the configuration of an
underground mine which permits ground water to preferentially encounter commonly acid-
forming units (seat and roof rock and the coal). Over time, roof falls and pillar deterioration
continue to introduce additional acid-forming materials into the system. Daylighting is radically
different than the mining processes that allow the underground mine to create AMD, because the
coal mine entries are eliminated and the gob is mixed with the remainder of the overburden. The
post-remining configuration of the daylighted sections becomes that of a reclaimed surface mine.
However, because of roof falls and pillar deterioration, there may be a higher amount of
unrecoverable coal mixed in with the spoil associated with daylighting than with remining
surface mines. After daylighting, and in the absence of selective spoil handling, ground water
flowing through the reclaimed portions will encounter acidic, alkaline, and/or relatively inert
spoil materials at a frequency based on the volumetric content of the spoil and on the ground-
water flow regime. With these changes to the ground-water flow and the materials contacted,
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Coal Rdmining BMP Guidance Manual
ill'; ' , , "iii!1! .lei . ' '.. ' '' . . ' . i" , ; .' >' ' i >', , . i. :"'i|' , ' ,"!, "!,.:,
mine water is likely to be less acidic, especially with the presence of alkaline units in the
overburden.
Daylighting of an abandoned underground mine on the Pittsburgh Coal seam in Allegheny
County, Pennsylvania resulted in turning mine discharge water from "extremely acidic" to
alkaline with low metal concentrations. The areas of the mine that were not daylighted continued
to produce acidic mine water similar to the premining water quality (Skousen and others, 1997).
I
Daylighting of underground mines can reduce pollution loads through the reduction of ground-
water infiltration and through changing the geochemical and physical properties of material that
I
3
pie ground water contacts. Daylighting eliminates potential recharge sources by mining out
subsidence features. The original ground-water flow path is interrupted by the subsequent
installation of seals and/or drainage systems. The potential amount of mine water storage is
likewise reduced.
!"',,, ,"'" ,;,, , ' ' " , , ' ,'.!, II ' , ,11:,'!
;'. ' ' ,,' Jlll'l||l: i'1;1;1 "'"'I! ; ' r ' T ';|, '' ' '' J -1'
Before an underground mine is daylighted, the ground-water system exhibits primarily open
conduit flow with water encountering seat rock, roof rock, and coal. All three of these units are
typically pyritic, and thus possible acid generators. Once daylighting has occurred, the lithology
and particle size of the overburden, whether alkaline, acidic, or inert, is greatly modified. This
modification of the overburden strata substantially increases the amount of freshly-exposed rock
I
surfaces that are accessible to the ground water. Following daylighting, the ground-water flow
I
regime is a dual porosity system, where ground water is stored in large conduits and voids
I
between spoil fragments, but exhibits overall intergranular flow characteristics through the finer-
grained spoil (Hawkins, 1998a). With this change in the ground-water flow regime, the
ป'' ' :":- ""- . ; .,. ' ' ';';, . . , , j ' ." . ...,. ; ;
probability of ground water encountering alkaline or acidic material is proportional to the volume
and surface area of that material in the spoil, whereas, prior to daylighting, the water almost
exclusively contacted acid-forming materials. The intergranular flow through the fine-grained
Spoil exhibits the lowest transmissivity and is the controlling factor of the speed of ground-water
flow in the backfill. Therefore, contact time with rock surface areas also is altered, and generally
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Coal Remining BMP Guidance Manual
lengthened by daylighting. These flow regime changes can have a significant impact on ground-
water geochemistry.
Potential problems do exist with daylighting. Overburden material can be highly acidic, and
disturbing it would allow for additional pyrite exposure and oxidation, release additional acidity,
and possibly increase the pollution load. To prevent this scenario from occurring, potential acid-
producing and alkaline-yielding zones, as well as the net acidity or alkalinity of the overburden,
should be determined prior to remining. If the overburden is acidic, the anticipated reduction in
flow that can result from daylighting may be offset by the additional acid production. In this case,
alkaline addition or some other ameliorating BMP would be required. In addition, coal itself can
be acidic (with total sulfur concentrations greater than 0.5 percent). The acidity potential of
unrecoverable coal needs to be included in the acid-base accounting conducted for the site.
Additional coal mixed in with the spoil and left in the backfill can be problematic for marginal
sites.
Another potential problem associated with daylighting is that underground mine workings have
often collapsed and pillars have crushed, causing coal to spall off. Under these.situations,
separating coal from the waste rock can be difficult, and some of the coal will be unrecoverable.
Industry estimates range between 5 and 20 percent of the coal may be left during daylighting.
Sealing and Rerouting of Mine Water from Abandoned Workings
As an integral part of daylighting, abandoned mine entries and auger holes exposed at the final
highwall are sealed with a low-permeability material. Sealing these abandoned workings inhibits
the infiltration of atmospheric oxygen. Sealing also prevents ground-water movement into these
workings from the mine spoil and from these mine workings into the mine spoil. Figure 1.2.1b
shows exposed auger holes that require sealing. The most common method of sealing an exposed
mine entry or auger hole is by pushing, and compacting as much as possible, a low-permeability
material into the abandoned workings with a bulldozer or other appropriate equipment.
Compaction of the material is difficult to achieve because the inside of the seal is open ended.
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Coal Rtmining BMP Guidance Manual
When a material is pushed into the opening, there is nothing on the inside to push against to aid
compaction.
Figure 1.2.1b:
Exposed Auger Holes
Achieving water-tight seals for auger holes and mine entries that have not been daylighted is
extremely important. If these seals leak, a fluctuating water table may be created for the
j , , ,
undaylighted portion of the underground mine. A fluctuating water table is possibly one of the
worst conditions in an underground mine environment. When the water table drops, pyritic
material is subaerially exposed, permitting oxidation. When the water table rises again, salts that
, i 1" MI,,'! '" ' . , nil. i ' I '...,,. ' ," '!" ' i t I!
were created by the pyrite oxidation, are hydrolyzed and mobilized, creating additional AMD.
The importance of sealing these mine workings should not be taken for granted.
, j ;,.:
1 "'''' ' ' .... j , ;, , , ;,.,,;,
In some regions, constructed mine seals may be permitted. In Tennessee, a "brick wall" has been
approved as a means of sealing exposed underground mine entries (Appendix A, EPA Remining
Database, 1999). On a site-specific basis, other types of constructed water seals may be
approved.
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It is highly recommended, and in some states statutorily-mandated, to seal mine entries and auger
holes to a depth equaling three times the widest dimension of the opening. For example, if the
auger hole is 3 feet in diameter, the depth of the seal should be at least 9 feet. Figure 1.2.1c is a
schematic illustration of a mine entry seal. Determining the depth of a seal is extremely difficult,
if not impossible. It is doubtful that a mine entry that is 10 feet wide is sealed to a depth of 30
feet.
Figure 1.2.1c:
Example of a Mine Entry Seal
Schematic Drawing of a Sealed Mine Entry
Not all states require that these mine workings be sealed to three times the widest dimension.
Some require that the sealing material be pushed into the entry as far as possible with a bulldozer
or other piece of equipment. Figure 1.2. Id illustrates this type of seal, as approved in Virginia.
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Figure 1.2.3Ld:
Example of a Virginia-Type Mine Entry Seal
Nonselective Backfill
Material
Most Impervious Push into Entry as Far as
Material Available Possible Using a Bulldozer
There are other problems with assessing the effectiveness of these seals. Daylighting abandoned
wbrkings often exposes numerous mine entries. Sealing of all exposed entries can require a large
amount of material and is difficult to achieve because the inside of the seal is open ended. For
example, if daylighting exposes 20 entries with average dimensions of 10 feet wide and 5 feet
high, sealing will require over 1,100 cubic yards of material. This is a considerable amount of
material to stockpile and handle, even if it is locally available. If not locally available, the
material should be obtainable at a minimal cost.
The permeability of this material should be similar to that required for surface capping or stream
lining material^ The material should exhibit hydraulic conductivities of 10"10 to 10"9 m/s or lower
to effectively inhibit ground-water movement. By comparison, coals in the northern Appalachian
i ' ,,'',':,' ' I ' ซ ,' I ,' : ii, ', '!,n ' f '" |, i1 i " ' " ป"' " ,i, , ' i ' ,|, N ;'
Plateau may have hydraulic conductivity values ranging from 10~6 to 10"5m/s (Miller and
!' ,' ',!,. ' , ' ' " ',!' ' ,'!',,,' I, jl '! "!', , " . ', ! i1
1 '_ " ' _ "" " !IT
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Coal Remining BMP Guidance Manual
Thompson, 1974). If these mine workings are sealed properly with a low-permeability material,
ground-water movement is more likely to be through the more permeable coal than through the
entry seals.
Daylighting operations commonly encounter mine discharge points and/or water pathways during
mining operations. The mine water will continue to flow through portions of the mine that have
not been daylighted. Therefore, sealing of mine entries can cause extensive flooding of the
remaining mine workings behind the seals. Under these hydrogeologic conditions, considerable
hydrostatic head eventually will rest against these seals, causing a substantial amount of mine
water to infiltrate into the backfill. This infiltration can occur even when seals are properly
installed. These flooded areas can be dewatered by installation of a free-draining piping system
to collect and transport the water through the entry seals and bypassing the backfill. The drain
system prevents mine water from being exposed to the spoil. Figure 1.2.1e illustrates this
potential-sealing scenario with the drain system in place. The system should be designed to
accommodate the maximum flow anticipated.
Figure 1.2.1e:
Example of a Mine Drain System
Drain Pipe
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si;;!' ';
t;
;.!["
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Coal R&mining BMP Guidance Manual
iHighwall Drains
There are two basic forms of highwall drains (horizontal and vertical) that work together or
separately to collect ground water entering the spoil from the highwall. Horizontal drains can be
installed to work on a stand alone basis. Vertical (chimney) drains usually are not installed as
stand alone, but are commonly tied into a horizontal drain. Highwall drain systems work to
ii" .I1' . ;. ' ; ; "t iif1 ', " ' ,: " ; ; i > .',,ซ,,! .. | ' rj, ', ' : , >
minimize or prevent the contact between ground water and potentially acid-forming spoil by
interception, collection, and transport away from the spoil. If the water quality is within
!,C ', ffj, :'i!ir,, , -j| V:., .. , , ..? ; >, ; ' '1 , Jx , -; : ,,? :
compliance standards, the water can be discharged directly. If not, it will require treatment prior
to release.
Highwall-drain systems can also function to collect surface water prior to infiltration at the
interface between the highwall and spoil. This horizontal-pipe system is installed with a
perforated pipe running along the surface or just below the surface, parallel to the highwall. The
surface pipe is connected to a solid pipe that runs from the surface to the pit floor, where it is tied
into a horizontal highwall drain (Gardner, 1998).
Chimney drains are highly-transmissive linear zones of rock installed vertically at the highwall.
Chimney drains collect ground water as it enters spoil from the highwall and channel it
downward toward the pit floor (Figure 1.2.If). These drains are usually installed at a known
inflow point (observed during mining), such as a ground water-bearing fracture or fracture zone
exposed at me final highwall. Chimney drains are usually tied into a horizontal drain installed at
the base of the highwall in order to channel the water away from the bulk of the backfill. Water
captured by a chimney drain is channeled to an integral horizontal drain located at the base of the
highwall. This water is then drained laterally and is subsequently discharged away from the
spoil. In some cases, a highwall drain also be constructed of perforated pipe buried vertically at
the highwall. If a pipe drain is used, it should be surrounded by coarse rock to facilitate drainage.
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Coal Remining BMP Guidance Manual
Figure 1.2.1f: Cross Section of an Example Chimney Drain
Buried Highwall
For chimney drains to work effectively, they need to be substantially more transmissive than that
anticipated for the spoil. A median hydraulic conductivity of 1.7 x 10~5 m/s was determined from
aquifer testing of 124 wells in mine spoil from 18 mines tested in the northern Appalachian
Plateau (Hawkins, 1998a). Drains should have a hydraulic conductivity two orders of magnitude
(100 times) higher than this value. The need for this difference in hydraulic conductivity is based
on the difference in the definitions of an aquifer and an aquitard. With a hydraulic conductivity
difference of two orders of magnitude, ground water tends to move through the aquifer and not
through the adjacent aquitard. The relatively-high hydraulic conductivity required for the drain
necessitates that the material is a uniform coarse-sized durable rock. Rock size can vary, but
should be large enough to ensure long term drain integrity and preclude piping of the drain
material. Drains comprised of rock one inch or larger have been successful. Inert, well-
indurated (cemented) sandstone or a limestone is frequently employed to ensure the desired life
span.
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Horizontal drains are commonly installed at or near the base of the final highwall to collect
grdund water entering from undisturbed strata or adjacent unrelated surface mine areas. Ground
and surface water often infiltrate into mine spoil at the highwall. If this water is not collected by
I chimney drain, it tends to migrate downward taking a path close to the highwall toward the pit
floor. Horizontal highwall drains are installed to intercept this water and remove it from the site
before the water encounters additional spoil. If present, chimney drains are tied into the
i.:: ' L ; : #< if ; <|j ." i - ' - _ - - > .', I ' " ' ,;1-"1 ' ' ' ' ' j ;
horizontal drain.
" i , , lilii!" , ' it1 < . "' ' I ' i , , . 1 i ' i i I
'in ' , "Til ",i . ' , " I ' . ; I
,,,,,,,, , ,|
Horizontal drains are either constructed directly on top of the pit floor or are incised a few feet
into the seat rock. The latter appears to be a more efficient method for collecting water. Figure
; ' ' '" , . ;";,; :;;; ! .', , ;, ' """ " ',';.. ,"'.,. ' ' ' ' '.'"' . . ;, 1: "'. ' . ' ,'" -:':
1.2.1g illustrates two common types of horizontal highwall-drain construction. These drains
consist of a perforated pipe placed into a core of coarse-grained rock. Rock composition and size
should be similar to that used for chimney drains. Pipe diameter should be large enough to easily
transmit more water than the predicted highest flow. Four or six inch diameter, flexible
i1'},! ''ill1', ., in. |U"1 3 : . j, '. '.'.,. , ,i( ' ' i. > It:1 , " j,! , : .1 ,.'' \
perforated plastic pipes are the more common pipes used for horizontal drain construction. At
sites where extreme flows are anticipated, a larger pipe diameter may be necessary.
Ji::1} i' "! !l ' '"Si! " l>|i .' , ' ' ., "' ป. i l! !, >! .'.Iv .1' '.';, -, ,ป . ฃ.i.i , ) . ,1
figure 1.2.1g: Cross Section of Horizontal Highwall Drains
Cross Sectional View of Horizontal Drains
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Drain orientation depends to some degree on the structural dip of the pit floor. Horizontal
highwall drains, as with pit floor drains (discussed in a later section), need to have sufficient
grade to properly drain water from the spoil. Once ground water enters the drain, it should flow
rapidly through the pipe and be discharged away from the site. These drains are designed to
prevent the formation of a defined ground-water table. If the drain system is ineffective, a water
table will form and some of the ground water will bypass the drain, continue to flow through the
spoil, and eventually discharge as mine drainage at some point down gradient at or near the toe of
the spoil. The drain outflow point should have an air trap installed to prevent atmospheric
oxygen from migrating back into the backfill and possibly oxidizing additional pyrite.
An important factor in the implementation of highwall drains is the collection and transportation
offsite of as much water as possible, before it encounters the spoil. A clear understanding of the
surface water drainage system and the ground water-bearing zones or fractures is imperative. A
good idea of from where the water will be infiltrating is required to design and install an efficient
highwall drain system. However, some spoils are so highly conductive, a properly installed drain
will collect the water shortly after it enters the spoil, regardless of infiltration points or zones.
Care should be taken to ensure that the drains have sufficient grade to efficiently drain water
away from the spoil and discharge it freely.
Pit Floor Drains
Pit-floor drains are similar in construction to and perform a similar function as horizontal
highwall drains. Depending on the dip of the pit floor, they can be tied into each other to create a
common drainage system. Pit-floor drains are designed to capture ground water that has entered
the backfill either through lateral or vertical infiltration. The water is then rapidly drained from
the site without intercepting additional spoil material.
Pit floor drainage patterns should be designed so that the majority of the ground water in the
backfill is collected and the ground-water table is greatly suppressed, if not eliminated.
Construction of pit floor drains is similar to construction of highwall drains, but the orientation
and layout design are substantially different. Figure 1.2.1h illustrates the cross-sectional view of
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[Coal Remining BMP Guidance Manual
two common methods for constructing pit floor drains, and two of the more common pit floor
drainage patterns. Efficient pit floor drainage is not exclusive to these two patterns. There are a
multitude of drain plan view layout designs that should work effectively to collect ground water.
The drainage pattern employed should be site specific.
Figure 1.2.1h:
Pit Floor Drain Patterns
Structural Dip of Strata
'. T "
Structural Dip of Strata
Vi 1 " ' nil
Outflow Points
Outflow Point
Dendritic Pattern
Extent of Mining
Linear Pattern
The dendritic pattern is similar to stream drainage patterns. There is a main stem with a series of
tributaries that intersect it at angles less than 90 degrees. This drainage pattern contains one
common outflow. Drain tributaries need to be positioned with respect to the dip of the pit floor
to allow water to drain freely. Tributaries also need to be at an oblique angle to the dip so they
will intercept as much ground water as possible, yet still drain properly. Air traps should be
placed at the outflow point to prevent atmospheric oxygen from migrating freely back into the
if" , ; !.;.; . ' ' ;: ' . ' ; .; ' < " *;s ' , j - - ,\
spoil.
The linear pattern is composed of a series of evenly-spaced parallel drains with each drainpipe
Having a discrete outflow point. These drains, like those of the dendritic pattern, need to be at an
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oblique angle to the dip, where a substantial amount of the ground water is intercepted, while
maintaining sufficient grade to allow free drainage off of the site. Air traps should be placed at
the outflow points to prevent atmospheric oxygen migrating freely back into the spoil.
Determination of the probable transmissive properties of spoil and the appropriate spacing of
drains is critical to the effectiveness of this BMP. Parallel pit floor drains installed on a site in
Westmoreland County, Pennsylvania, were spaced at roughly 500 to 600 foot intervals. Figure
1.2. li shows the construction of a pit-floor drain at this site. Preliminary monitoring results
indicated that this spacing may be too broad. Monitoring wells indicated the presence of a
defined water table in parts of the backfill, and water levels in the monitoring wells were
typically 3 to 5 feet above the pit floor. The drains installed were not completely suppressing the
ground-water levels, but were keeping them lower than expected for nondrained spoil. The spoil
at this site is comprised almost entirely of shales, which caused the backfill to be less
transmissive than originally anticipated. Sandstone-rich spoils are expected to be more
transmissive, requiring a wider drain spacing than shale-rich spoils. In this case, the drain spacing
was inadequate for the given site conditions. Future operations should be specifically engineered
to account for the expected spoil hydraulic properties.
Figure 1.2.11: Example of a Pit Floor Drain
-
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^ t^^^l-S-* ' ^> Vl-"f^C Jjr^5^^~*t^~^>'^%sf^.c
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;< _ฃ -ja.; ssSf^s^^ "-, -SJ --^ -' ^
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i i"
1! : I- :f,
"I; ;
The engineering and construction of pit-floor drains are critical to their efficient use. These
drains should be installed so they intercept the ground water flowing across the pit floor, with
Sufficient grade to drain water freely. Too broad a spacing between drains with regard to the
I; ;,. ',..'* ' t'i'j ,': iti'ljliii ' ! :;i . " ',' "I , . , ' " if' "'" " '! '' " 'i'ilil'!"1 '""'' '',. I i" ': 5 i'fk -, ' "." "'":i 'li
spoil hydraulic conductivity and expected heterogeneity will permit the formation of a water
Iwi; V, ' :' .1.' "! li ' ' i'-' ' i "'i ' \ " . ii ' ; ' ,' ... ,,:.';, I : ' ' .!'. (' , ,/ : , ' ' I
table between the drains. Drain spacing and configuration should be based on a forecast of the
' ' : . "i ,:; "" ; ' '"::, , ' ' > : ' . ':,;, :, ," {:. : .. ' '
spoil hydraulic conductivity and heterogeneity based on overburden lithology, mining equipment
III i V - ' I III . '! ''" - i . .. , ' '! , :; . '.' . . '" |l'i';; ,: ',' '.' j ' '" ' " '"
^mployed, direction of mining, and direct aquifer testing on nearby reclaimed surface mines.
There is a caveat with incising drains in to the pit floor. Excavation into a pit floor can breach the
, , , . . ... , i
integrity of the seat rock and facilitate infiltration of mine water into underlying aquifers. Once
( '! 'i =. .,,'W' 'IH'II i . " I;!1!" , . , ,,.' "I, , i- I" . ,,., i i*1 nil ,'i'1 , ;. i I < ' , ; '.,
ground water infiltrates into underlying units, it is less controllable and can eventually discharge
:I,"HI . 'j,,,,!!' ;, ,., ipnj ," Si " ' , , " , , . ' , ' : , ' H,," if, ,- , I, i , ซ ' i
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Coal Remining BMP Guidance Manual
compacted clay used to cap an acid-producing waste rock site. The importance of compaction of
the barrier material in the creation of a low-permeability barrier should not be overlooked. A
continuous barrier is needed to effectively prevent ground-water movement. Any breach in this
barrier can permit ground-water movement from the strata into the spoil.
The "haulback" of CCW to a mining operation is often a provision of the sale of coal to electrical
generating facilities. With the addition of water, CCW is often pozzolanic (self cementing). The
permeability of this material, once hardened, is sufficiently low to nearly preclude all ground-
water flow. The Electric Power Research Institute (EPRI) reported a range of hydraulic
conductivities for "self-hardening ashes" of 3.2 x 10'9 to 1.8 x 10'7 m/s (EPRI, 1981). These
values were determined after a 28 day set-up period. Hellier (1998) reported a hydraulic
conductivity of 10~9 m/s for a fluidized bed combustion ash used for a surface mine capping
project in north central Pennsylvania.
At some mining sites, the a grout curtain is installed at the highwall after reclamation has been
completed. In these cases, the spoil directly adjacent to the highwall has to be re-excavated and a
slurry-type grout used to fill the trench. Though grout types can vary considerably, grouts
containing high percentages of CCWs and cement or bentonite and cement are frequent choices.
Potential problems can arise from highly-permeable spoil. If grout is watery and flows too freely,
it will enter the spoil, and construction of a continuous, effective barrier is difficult. This grout
curtain would be expensive and probably cost prohibitive for renaming operations.
Grout curtains also can be installed above the highwall in undisturbed strata by performing a
pressure grouting operation. A series of boreholes are drilled across the site parallel to the
highwall. These holes are often drilled in a staggered pattern to maximize the grouting potential
by accessing as many natural fractures as possible (Figure 1.2.1J). Spacing of boreholes varies
depending on fracture density and transmissivity and on the propagation characteristics of the
grout. Grout holes drilled on ten foot centers have been suggested for sealing underground mines
(U.S. Environmental Research Service, 1998). Given the common orientation and density of
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::/ , ;; ,,; , .. . . , . ; ,,,;,, ;. j , , , ,: :,,:,
Stress-relief fractures in the Appalachian Plateau, drilling grouting holes at a slight angle (up to 3
degrees) from vertical will help to optimize efficiency. A commonly-used!!'pressure grouting
, . i ,, ,, ,.... i , i i ,,..,.. ... ,, J.,
,?imaterial is a commercially available polyurethane. The polyurethane is a two component
material that is injected simultaneously in equal amounts (Ackman and others, 1989). Other
1; i :;:-'.;'!!'!"!v , """ ';. ';'.-. !, ' i , ;":ii; ? "< ; '*'* 'ir, !'"!^^ '" . . ;. .
materials suitable to this type of grouting, are neat cement or bentonite.
Figure 1.2.1J: Common Drilling Pattern for Pressure Grouting Wells
Plan View
; M"
Drillholes
y . v
"A/!;, , i! I
Highwall
Problems with the implementation of grout curtains are often related to the continuity of the
emplaced grout. Ground water is expected to impound behind a grout curtain and eventually
flow laterally away from the spoil. If the grout curtain is not continuous, ground water
eventually will flow through a breach, following the path of least resistance. Pressure grouting in
fractured rpck aquifers is particularly problematic, because the fractures are not continuous, are
not all interconnected, and do not necessarily interact with one another. It has been observed that
individual fractures may represent discrete aquifer zones and may have distinctly different
I,,! i I,,,is',, ii, ,i' "'fill! ' ' ': ' , ,ii ',.,!,' |h . !!,, " j , ' .'niti, ,,, " ,;, 11,];'.,'I ' jr',,, ]' ' , ; i :,
piezometric surfaces (Booth, 1988). Rasmuson and Neretnieks (1986) estimated that only 5 to
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20 percent of the fracture plane transmits 90 percent of the water. A study of overburden
material at a surface mine in Clearfield County., Pennsylvania, illustrated that only a few discrete
fractures intercepted by a borehole actually contributed to the well yield. The remainder of the
fractures appeared to be unconnected or poorly connected to these active fractures (Hawkins and
others, 1996). Grout hole spacing, grouting material, and grouting pressures need to be designed
to overcome these potential fracture discontinuity problems. It is recommended that grouting
wells be drilled at a slight angle from true vertical to increase the likelihood of encountering
vertical or near vertical water-bearing fractures.
Ground-Water Diversion (Interceptor) Wells
Diversion wells are installed specifically to intercept and collect ground water prior to infiltration
into reclaimed backfill. These wells are drilled upgradient of the backfill area and can be oriented
vertically or horizontally. Care should be taken not to over pump these wells, causing ground-
water flow reversal. If the water table is lowered to the point that ground water is drawn from the
reclaimed operation, the water may require treatment prior to discharging. The intent of diversion
wells is to prevent water movement into the strip, not to create a pump-and-treat operation.
Vertical diversion wells require a pumping system operated by a consistent power supply. In
order for vertical diversion wells to effectively intercept ground water, a series of wells drilled
normal (perpendicular) to the structural dip and up gradient are required. Spacing of these wells
depends on site-specific conditions, such as fracture density, hydraulic conductivity, and
structure. Well depth is generally to or a short distance below the top of the seat rock. In
relatively shallow wells (less than 200 feet) of the Appalachian Plateau, the highest well
production occurs at the shallowest depths (Hawkins and others, 1996). However, there are
circumstances where substantial ground water flows in from deeper fractures. In competent
rocks in the Appalachian Plateau, the entire borehole should be left open to prevent restriction of
any ground-water inflow points. As with grouting boreholes, these wells may be more efficient
if they are drilled at a slight angle (1 to 3 degrees) to increase the probability of intercepting
vertical fractures.
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Coal Retaining BMP Guidance Manual
Diversion wells should be configured so that pumping will initiate when the water reaches a pre-
! 'I ]"''ฃ ' .'I'; ''' '!!, jjjiill ' , i ;':' ,11'1 ":'! ' !' , , "l*v r" ;' ".',1 II ', :.: ,,ll ' ' "' i | ,1 , ," IIMlllljlilr
defined level above the bottom of the coal and that pumping will cease once the water is drawn
down to second pre-defined level, commonly at or near the base of the coal. Pump cycling times
depend on the amount of ground water present, transmissivity of the strata, and the efficiency of
" . :" :";*: ';:::::: , " : . :; " ;;;- - . r , "L - : ".;; ;i:i" ,;
the well. Diversion wells are relatively inexpensive to drill, but can be expensive to complete
Iff, " , , '" , '"yiijli "iijlj, i ' i ', , - ' ' ' "" ,i II, ."!!!" , ' .,.,'..' 'I
and maintain over a period of time. Therefore, they will seldom be an economically viable
option for remining.
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Horizontal diversion wells, when properly installed, may be more efficient and effective than a
series of vertical wells, depending on the size of the area to be dewatered. The initial cost of a
i'!", ,:,!, !i, ',!:'!' ii;f1j , "'"ifj ' / " ,,,";" - ,' ';""!'', t", > ,,, , .' .:],:, ,, , "Ir;|l"j,1. 'ji 5^ : , f;; "nii| 1 "J1, ,, ' ...i i: '"jjlU11 ,, ซ ,,,.:; ,', ';!M ,f ,' ! J .Xjjjt
fhorizontai well will be dramatically more than the equivalent footage of vertical wells. However,
,"'., , ' "'" ' ' ii'5 1! [IP1 1! I' ", ; . !,! ' , "^ !i , > :" ' . , ,. ;, - ' ' J!1 ,,:' ;,'',",!, MI ' ",, ..... |'r'ป! i i, ir r ,:;,-' r, , ,'': ,\ im
ir;'there are definite advantages to horizontal wells. They can be drilled to allow for free drainage.
pumping system or power is required with a free-drainage system, an(i^m^
maintenance is required. Horizontal wells access water from a continuous horizontal line, rather
than from discrete well points, and are more likely to intersect water-bearing fractures. Because
..... I
pf the high cost of outfitting and maintaining the pumping systems of vertical well sets and the
I."1:1'! ' i "' : ...... r '";, :* ii: ;' ,ii!< , ,;' '""!'i, ' '" , '! " l : ' ,i , , ! " ; : ' ' ii''.! " ,,!' ..... J ' '" ' ., ซ" UN ป
initial high" cost of drilling horizontal wells, it is doubtful that diversion wells will be an
economically viable option at more than a few remining operations.
;',,The installation of diversion wells encounters some of the same poor fracture interconnection
problems as are incurred during the installation of grout curtains. Because individual fractures
pan represent discrete piezometric zones (Booth, 1988), diversion wells need to be drilled in a
'i'.'.'. ". ,.: :: , '..''. :. ' , ' ' .. : ''.:: . I,
configiiration and at a spacing that accesses all of the discrete ground-water flow systems. A
common occurrence hi the Appalachian Plateau is for shallow water wells (less than 200 feet) a
short distance apart (less than 100 feet) to show little interconnection based on an aquifer test.
111;, , i,it1! *i . " "", iv "" . . .., ,, ,' ii1, ' : inซ"' , . it,' JL'41 ' -I ,,; ,..! I- ji1;*,
Drawdown at a pumping well may exceed 100 feet while a well 50 to 80 feet away may only
exhibit a drawdown of a fraction of an inch over the length of a pumping test lasting 2 hours or
more. It is advised to drill to the vertical diversion wells at a slight angle from true vertical to
increase the likelihood of encountering vertical or near vertical water-bearing fractures. It is also
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Coal Remining BMP Guidance Manual
recommended to drill horizontal diversion wells at an angle to the preferred orientation of the
vertical stress-relief fractures. Because vertical fractures are created by tensional forces and tend
to be oriented parallel to the strike of the adjacent valley (Borchers and Wyrick, 1981), horizontal
diversion wells should be drilled at an angle that is subparallel to the valley orientation.
Design Criteria
These BMPs should be designed and implemented to preclude the lateral infiltration of ground
water into the backfill areas of reclaimed renaming operations. Some of the salient design criteria
for each of the BMPs discussed in this chapter are included in the list below. Site-specific
conditions will ultimately dictate which BMPs should be used and the scope of BMP
implementation required in order to reduce or eliminate lateral ground-water inflow, discharge
rate and pollution load. It should be noted that although grout curtains can be employed as a
BMP, they are rarely used and the technology is unproven.
Daylighting
Eliminate subsidence-induced ground-water infiltration zones.
Eliminate vast ground-water storage areas.
Reduce the amount of ground-water contact with acid-forming materials.
Increase the possibility of ground water contacting alkaline materials.
Facilitates special handling of acid-forming materials.
Greatly reduce the oxygen flow to the subsurface.
Sealing and Ground Water Rerouting of Mine Workings
Inhibit atmospheric oxygen infiltration into mine workings.
Use low permeability sealing material (e.g., equal to or less than 10'9 m/s).
Install seals to preclude ground-water movement into or out of the mine workings.
Drain to control the ground-water buildup, bypass the spoil, and discharge off site.
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Coal Remin&k BMP Guidance Manual
Hiahwall Drains
".. . ':. '-. . . j
Intercept and collect ground-water infiltration at the highwall.
i!i!if[;i -1,1' ' ' .i1'1"!""""' flit, *'.
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Coal Remining BMP Guidance Manual
Daylighting
Verification of the amount of daylighting that has occurred is relatively easy. The acreage
disturbed can be viewed during mining and after reclamation and compared to underground mine
maps. If there is uncertainty of the exact amount of daylighting that occurred, the area can be
surveyed.
Sealing
Verification of the implementation of sealing of abandoned mine workings will require the
inspection staff to be present during different phases of the operation. Once seals are in place,
they will be covered. If there is concern that the mine workings will not be properly sealed, the
permit may be conditioned to require notification when sealing will occur or will be completed.
The material to be employed to seal the openings may need to be stockpiled on site to confirm
the type of material and the amount to be used. The stockpile should be marked to distinguish it
from spoil or topsoil piles. To be sure the material has a sufficiently low permeability, the
relative hydraulic conductivity also may need to be certified by laboratory testing. As previously'
stated, it is extremely difficult to verify the depth to which the seal is emplaced. If this parameter
is deemed important enough, boreholes can be drilled behind the seal and a borehole video
camera can be lowered to view the seal from the inside and/or to monitor the flooding of the
remaining mine voids. It is doubtful that this step will be necessary.
Drains
If drains are installed in conjunction with the seals, drain piping can be viewed as it is installed.
Drain outflow can be monitored to determine if it is yielding the anticipated volume of mine
water. That is, does the drain yield a similar volume before and after mining. A mine
consistently yielding 300 gpm prior to mining and drain installation and a median flow of 85 gpm
after reclamation would indicate that the seals and/or the drain are not functioning properly. The
existence of toe-of-spoil seeps may also indicate that the drains are working improperly.
Pit floor drains are installed as mining progresses, and tend to be extended with each phase (cut)
of the mining operation. Pit floor drains can usually be inspected during several phases of the
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Coal Remining BMP Guidance Manual
operation. Effectiveness of these drains can be determined once the backfilling is complete. If
the drains are yielding water and unexpected discharge points (seeps) are nonexistent, it is an
indication that the drains are effectively collecting ground water. Monitoring wells installed in
the backfill provide the best indication that the water table is being suppressed as designed. Site
i
I
monitoring should be continued for a period beyond the anticipated water table re-establishment,
and monitoring through several wet seasons is important. In the Appalachian Plateau, the
backfill water table can require at least two years to completely re-establish.
Grout Curtains
The type of grout curtain installation monitoring depends on the method used to install the grout
curtain. If the curtain is created as the site is backfilled, an inspection staff can review portions
(lifts) of the installation as it progresses.
IJ ;:!!! , , ' ' "',1' ' In " : , i| ' "' I1 , - ' ll " ' , i
In situations where the installation of a grout or clay curtain along a significant portion of a
i ' i !iii ,i li " ...' '" ' l|i;l T' i',. i i ป;, 'I1.1.1 ป ;: ;' " :iป, i1" , M," ;" i11' t ' i! n ' ป , , :, i, i.j
highwall takes a protracted period of time and the inspection staff cannot be present for every
|tage implementation, estimates of the amount of material required should be submitted as part
if , '"iiiiJ r7.ii : " ./.IB' 5 .( ': " ' '>"\\^': ":, " v - : '. tf-t . ',;., i ; ',' ' : <
of the reclamation plan. Marked stockpiles or weigh slips equaling the proposed volume can be
JiiJk1 ' "' ," Ill1' ' "'iiiiiiK"! ,' .' 'i , , , ' " ' i .'! i1 'i ':,'",.", i "Mi ;; ''(.' .' i ;. il i i
used to determine if the proper amount of material was used.
Determination of the success of grout curtains emplaced via pressure grouting drill holes is
substantially more difficult. Grouting effectiveness can be evaluated indirectly by comparing the
estimated porosity of the strata, the total volume of the strata, and the volume of grout employed.
The ultimate effectiveness of grout curtains, regardless of how they were installed, is whether
they preclude ground-water movement through them. To make this determination, monitoring
wells can be installed on each side of the grout curtain.
Diversion Welts
There is little that can be viewed at the surface during the installation and use of diversion wells
to ascertain their efficacy.
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The effectiveness of diversion wells can be estimated by the amounts of water pumped from
them and monitored by the construction of monitoring wells both up and down gradient of the
pumping wells. If the down-gradient wells exhibit a suppressed ground-water table over the
anticipated levels, it is indicative that the diversion wells may be functioning properly.
Ultimately, if discharge rates are reduced, the diversion wells are effective.
Implementation Checklist
Monitoring a site for anticipated changes is a critical and inherent aspect of BMP implementation
and efficiency determination.
Monitoring should continue well beyond initial water table re-establishment period (e.g., about 2
years after backfilling). The list below is a recommended guideline for an inspection staff to
monitor and evaluate ground-water control BMPs.
Measurement of flow and sampling for contaminant concentrations at time-consistent
intervals.
Assessment of hydrologically-connected units, as well as individual discharges, for
pollution load changes.
Review or inspection of sealing material weigh slips, receipts, or marked stockpiles.
Review of implementation initiation and completion dates
Assessment of any deviation from an approved implementation plan.
Inspection of salient phases of the BMP implementation for:
a. integrity of seals.
b. drain construction, location, and orientation.
c. grout curtain integrity and continuity.
d. diversion well locations and productivity (yield).
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'! !'H [1 fill I Iff "',ซ IB'! 1 It;.: IE *'? '5 "PI! F' 11ll!' ซ II'"? "I " U,!' 'ill: 5 '' I' !*
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Coal Remining BMP Guidance Manual
1.2.3 Case Studies
Case Study 1 (Appendix A. EPA Remining Database. 1999 PA(3))
"' '" ' '"'
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I
Remining was performed on an abandoned surface mine and abandoned underground mines in
'!'" " I'll'li ."I.'',!'!! , ' ' ,, ' i ,!, ",', , ' ' ' 4' i , ' ",,,' ' '! i!!1 ' !: ' I |T ' , .|,, ,
the Pittsburgh coal seam. A total of 33.8 acres (48 percent) of the 69.6 acres of abandoned
surface mine land within the permit boundary were reclaimed by the operation. Of the 90 acres
of abandoned underground mines in the Pittsburgh coal seam, at least 49 acres (54 percent) were
daylighted during the remining operation. More than 203 acres were impacted by the remining
operation. Fourteen pre-existing mine drainage discharge points were included in the permit.
BMlPs listed in the permit included regrading of abandoned mine spoil and highwalls,
underground mine daylighting, sealing of exposed mine entries, special handling of toxic
materials, and revegetation. The most predominant BMP components were
regrading/revegetation and daylighting. The site was completed in June of 1998. Ten discharge
points were used to determine the impacts of remining. The remaining four discharges were low
i
flow and discharged intermittently during pre- and post-mining periods.
I
,, , , I,. ., ii. ,. , J . ~~ i
Because this site has been reclaimed relatively recently and post-remining data are limited, the
resulting pollution load analysis is less than ideal and subject to change. However, this site is
worth evaluation because of the large percentage of daylighting that was implemented and
because it drains to a stream that is used as a public water supply. Additionally, considerable
discharge reductions were observed prior to final backfilling for several of the monitoring points.
Two of the main discharges (MP-1 and MP-4) began to exhibit significant flow reduction prior to
the completion of reclamation. Prior to October, 1992, MP-1 ranged in flow from 0 to 139 gpm
with a median of 18 gpm. Since October of 1992, MP-1 ceased to flow, except for one monthly
sample where the flow rate was 0.25 gpm. The flow rate of MP-4 ranged from 0 to 132 gpm
with a median of 6.9 gpm prior to April of 1994. After that time, the flow ranged from 0 to 18
gpm with a median of 0.1 gpm. Figures 1.2.3a and 1.2.3b illustrate the flow reduction exhibited
by these two discharges over time.
I!!,'!'!:,-',,, , ,: i... ฐ .- ,, . . i .., ., i , , ,,,
1-60
Hydrologic Controls
., I" ,. Ei" .i,,.,1! ปB!
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Coal Remining BMP Guidance Manual
Figure 1.2.3a: Change in Flow Over Time (Case Study Discharge MP-1)
PA (3) MP-1
150
-S120
8
H
90
60
30
Pre-Mining
Post-Mining
Figure 1.2.3b: Change in Flow Over Time (Case Study Discharge MP-4)
150
PA (3) MP-4
Pre-Mining
Post-Mining
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These analyses indicate that a flow reduction was observed even prior to complete backfilling
(Figure 1.2.3c). MP-1 and MP-4 are directly down gradient from the first areas to be mined and
reclaimed, and down gradient of limited-sized recharge areas. Therefore, it should be expected
that these points would exhibit the greatest change during remining operations.
'I 'W!' i' ill.""",'
Figure i.2.3c:
Flow Rate Reduction, Pre- and Post-Remining Periods (Case Study
Discharge MP-4)
0
PA(3) MP-4
8/4/85 4/30/88 1/25/91 10/21/93 7/17/96 4/13/99
Date
Pre- and post-remining comparisons (discharge points MP-2, MP-3, MP-5, MP-6, and MP-D)
exhibited no apparent change in flow. However, flows for MP-A and MP-B appear to have
decreased slightly, although not significantly. Although MP-C shows a slight, but significant,
I ," ' , i,,1 '"{.if"' ' ,'!!'!!' ป" ,.,;..| ... ' , i ' , ,. , i'1'"',,;,, , '' fti!,;.'", " . ii !,!, I,.'.' ; , ', v i :ซ ' ' ,1 ''I!
!!! ,i ป, ' , ;, tiii II'TJ / " ' !; , i , ,, i , , i ,;, '4f'4"f ' ' ' . IM' '. JI ' , nf | ,"!iii|||ii,,'
increase in median flow (from 0.5 to 2.9 gpm) from before to after November of 1994, the actual
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change in flow is relatively low by comparison to flow rate for most of other discharges.
Analysis of the post-mining data is, at this stage, preliminary. Only data for the first two months
after remining were submitted for four of the discharges (MP-4, MP-5, MJP-C, and MP-D) and
these discharges have been excluded from the evaluation of pre- versus post-mining water
1-62
Hydrologic Controls
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Coal Remitting BMP Guidance Manual
quality. Four of the remaining discharges (MP-1, MP-6, MP-A, and MP-B) exhibited a post-
remining median significantly below the background data at a 95 percent confidence interval.
This improvement in water quality is illustrated in Figure 1.2.3d. Three of the discharges (MP-1,
MP-A, and MP-B) have been nearly or completely eliminated. The two remaining discharges
(MP-2 and MP-3) exhibited a median flow rate reduction that was not statistically significant.
Figure 1.2.3d:
Flow Rate Reduction, Pre- and Post-Remining Periods (Case Study
Discharge MP-6)
80
60
o
E
20
0
PA(3) MP-6
Pre-Mining
Post Mining
The results discussed above should be tempered with the knowledge that precipitation for the 32
month baseline period was near average (i.e., a mean of+0.05 inches per month), while the brief
post-remining period (6 months) was significantly below the average (i.e. a mean of-0.50 inches
per month). Post remining monitoring should be continued until the precipitation has returned to
near average for several months (preferably 6 to 12 months) and the water table has been fully re-
established. Precipitation data were compiled from the Pittsburgh International Airport,
approximately 37 miles west of this mine site.
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m'.Coal Returning BMP Guidance Manual
utt 2"
ป EPA Remining Database, 1999, VA(7))
v 1:
This site is located in Wise County, Virginia. The coal seams being remined are the Imboden
Marker, tgvve'r Kelly, Upper Kelly, Kelly rider, Lower Standiford, Upper Standifbrd, Taggard
Marker, BQtton| Taggart, Top Taggart, Owl, and Cedar Grove.
ฃThe permitted acreage is 1,140, with 149 acres to be regraded, 158 to be reclaimed, and a total of
498 acres to be disturbed. Daylighting will occur on previous augering of the Standiford seams.
Abandoned mine workings will be daylighted on the Upper Standiford. It is also probable the
abandonecJ mine workings on the Upper and Lower Kelly seams will be intersected and partially
;. ,? dayKghtedt
There are three discharge points (SB-5, SB-6, and SB-7) that were identified as pre-existing mine
discharges. Although this site was still active as of January 1999, it is worth evaluating because
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,|l 'Li, u, ..... n, i",,, 1 '!!"' ,11 il'iiii!!'1!!'"'! I. ' '"...Illl1! ...... ' ' ! N. ' J\ ''" ..... , ! '! >i: ' i '' ,: ป I'l/i ! i1: ' . " ' ''llill'illllil'! ! .1 , 'i | . ,' l'i .(i", '' , '' , , i/i'1' ' il, >,;!!
it illustrates ; the .type of remaning occurring in Virginia and a substantial amount of daylighting
and sealing of abandoned mines and auger holes is being performed.
IIIII'T,,! ".I ' ซ' " 'fl.II,, || I ' SMd ....... I ',, ,' ....... ,'" ',,, ' 'II! , ฐ , ป, , ......
' ' ' ' ' '
Preliminary analysis of flow data yielded mixed results, but indicates an overall flow decrease.
A comparison of baseluie flow rates to flow rate during mining indicates that two of the three
:ป; :, :. ' .:ซ:; :::ซ : . .-.. ป ....... ..... ' ., ,* ': :: ..... ; &.-. ; ! ' " , '. '
discharges (SB-6 an SB-7) have a reduced median flow.
The reduced flow was significant at a 95 percent confidence level for SB-7. SB-5 exhibited an
insignificant increase in median flow for the same time periods. The sum of the median flows
for baseline was 97 gpm compared to a median 53.5 gpm during remining, yielding a possible
i
flow reduction of 45 percent. Evaluation of these results should acknowledge that climatic (e.g.,
precipitation) conditions were not considered during the analysis. Long term post-remining
monitoring with determinations of precipitation during the same period, as well as that for the
background period will yield a true assessment of the impact of remining on the pollution load.
' 1-64
Hydrologic Controls
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Coal Remining BMP Guidance Manual
1.2.4 Discussion
The BMPs discussed in this chapter, when properly employed under the right conditions, will
successfully reduce the lateral infiltration of ground water into the backfill and should
subsequently reduce the discharge rates. However, these BMPs cannot be viewed as a panacea
for all of the pre-existing problems at a site. There are limits to what can be physically achieved
and/or economically attempted. The two lists below (Benefits and Limitations) include, but are
not limited to, what should and should not be expected of these BMPs.
Benefits
Reduce pollution loading from abandoned mine land.
Establish an alternate, improved hydrologic balance at the site.
Eliminate surface subsidence features (e.g., sinkholes, disappearing streams, etc.).
Highwall drains can be installed at the observed infiltration points.
Control of the location of post-mining discharge points in case treatment is required.
Daylighting often results in little profit, however, it is implemented as an integral part of
the mining operation.
Special handling of acid-forming materials.
Reduction of oxygen flow to the subsurface.
Limitations
Current implementation of these BMPs lacks comprehensive evaluation of effectiveness
for pollution prevention.
Previous use of some of these BMPs (pit floor and highwall drains, highwall sealing, and
diversion wells) has been limited, therefore the true extent of their effectiveness has not
been adequately determined.
The true effectiveness of mine seals, drains, and grout curtains installation cannot be
determined prior to reclamation and establishment of the post-mining hydrologic regime.
Given the highly heterogeneous and anisotrophic nature of surface mine spoil, the present
state of predictability of the post-mining ground-water flow system is limited. It is
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Coal Remitting BMP Guidance Manual
doubtful that an extremely high degree of predictability of the efficiency of highwall and
pit floor drains is possible.
Complete exclusion of laterally-infiltrating ground waters is not likely, therefore there
needs to be a realization that the discharges will likely not be entirely eliminated.
Diversion wells are costly and even the best planning may not provide an effective BMP
system, if the hydrologic system is poorly understood.
Success of daylighting can be dependant on the geochemistry of overburden material and
, !' Ill .'iii'Ii ", ' " ! ..... il, ป ijili, k |,| ' i.: ,"' li , , .' ' '" I ,', ', , ' ' ' ' II ' I "iii1!
special handling of acid-forming materials.
.. ..... , ,. - /,.
Efficiency
Analysis of completed remining sites in Pennsylvania (Section 6, BMP Efficiencies) indicated
that at least 90 percent of discharges impacted by ground-water control BMPs will either exhibit
a significant improvement, no change in the pollution load, or be completely eliminated (in the
case of manganese, 89.5% of the affected discharges were improved, eliminated or unchanged).
For a total of 164 discharges with elevated acidity levels from remining operations in the state of
Pennsylvania (Appendix B, PA Remining Site Study), slightly over 43 percent _were improved or
eliminated, over 56 percent were unchanged, and less than one percent were significantly worse
from daylighting.
a;!:1-'1 'ซ
, ..,
Kti," 1
Of the 156 discharges with elevated iron, nearly 40 percent were improved or eliminated, about
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55 percent were unchanged, and over 4 percent were significantly degraded from daylighting.
Similar resjiltswere yielded by analysis of aluminum and manganese loads. In regards to iron,
acidity, manganese, and aluminum, the percent of discharges that were degraded during
daylighting was never greater than 6.5.
Analysis of the implementation of special water handling facilities, tabulated in Appendix B,
yielded similar results. However, this category includes both surface and ground-water handling
facilities. Fifty percent of the 22 affected discharges exhibited an improvement or elimination
i
for acidity loading with the remainder showing no significant change. Almost 48 percent of 23
i
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Coal Remining BMP Guidance Manual
discharges exhibited an improvement or elimination with an additional 48 percent showing no
significant change for iron loading. Slightly over 4 percent were significantly degraded in
regards to iron loads. Manganese loadings showed that 47 percent of the 20 affected discharges
were improved or eliminated and 42 percent were unchanged. The analysis indicated that
slightly over 10 percent of the discharges had been degraded in regards to manganese loadings.
Aluminum loads exhibited similar results with the bulk of the discharges (73 percent) being
unchanged and none showing degradation.
Overall, the analyses of acidity, iron, manganese, and aluminum loading data from these
completed remining sites indicates that between 90 and 100 percent of the discharges will show
no degradation from daylighting or special water handling. Additionally, between 27 and 50
percent of the discharges will be improved or completely eliminated. These efficiency numbers
can be improved with the specific tailoring of the BMPs to reduce or exclude lateral ground-
water movement.
1.2.5 Summary
Previous studies have shown that the extent of pollution reduction from remining is largely
dependent on reducing the discharge rate, which in turn is dependent on the controlling the
infiltration of ground water into the backfill. The commonly-observed positive correlation
between flow and loading rates illustrates this close relationship. BMPs designed and
implemented to prevent ground-water infiltration from adjacent areas will be successful in
reducing the pollution load and in some cases may completely eliminate the discharge.
Case Studies 1 and 2 illustrate that underground mine daylighting, entry and highwall sealing,
and other ground water-controlling BMPs can yield mixed results unless differences in
precipitation rates are taken into account and the post-remining monitoring period is of sufficient
length to accurately reflect site conditions. However, it is well known that these BMPs, when
properly implemented, will reduce the contaminant load from remining operations.
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1-68
Hydrologic Controls
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Coal Remining BMP Guidance Manual
1.3 Sediment Control and Revegetation
Erosion and sediment deposition caused by weathering and precipitation are natural processes
that can be accelerated in disturbed watersheds. Disturbances such as surface coal mining
involve the removal of vegetation, soil, and rock. Spoil or highwall surfaces create conditions
highly vulnerable to erosion and result in adverse sediment deposition that can clog streams,
increase the risk of flooding, damage irrigation systems, and destroy aquatic habitats. Sediment
deposition in downslope areas can have adverse environmental impacts on watershed soil and
vegetation. Abandoned surface mine land, spoil refuse and gob piles often have exposed
surfaces that are vulnerable to erosion or conducive to high rates of storm water runoff resulting
in increased problems of sedimentation in receiving streams. Re-exposing these abandoned sites
during remining operations without concern for sediment control can cause serious solids loading
and hydrologic imbalance. Successful implementation of erosion and sediment control BMPs are
critical for ultimate landscape stability and receiving stream protection.
Theory
The implementation of the BMPs discussed in this section for management of surface water and
ground water at remining operations also can form the basis for sediment control. If
implemented properly, site hydrologic controls can serve to prevent erosion, solids loading into
receiving waters, and unchecked sediment deposition. Likewise, if hydrologic controls are
implemented without consideration for potential sedimentation, conditions leading to discharge
of solids and sediment can rapidly increase and result in severe environmental degradation.
Remining and reclamation of abandoned mine lands typically require techniques that involve
regrading to approximate original contour, replacing topsoil, applying vegetation amendments,
and constructing erosion-control structures. The resulting reclamation often is aesthetically
pleasing, but can result in an artificial drainage system that can be problematic and accelerate
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Coat Remining BMP Guidance Manual
erosion as natural drainage systems are re-established. If reclamation techniques fail to consider
natural drainage patterns and surface water flow characteristics, conditions can become worse
than those that existed prior to implementation of these techniques. Sedimentation and erosion
problems can be alleviated by proper implementation of some or all of the BMPs discussed in
this section.
i
Site Assessment
i
Prior to implementation of BMPs to control erosion and suspended solids loading, sites should
be assessed to determine existing drainage patterns and topography, to quantify effects of storm
runoff and the yield of coarse- and fine-grained sediment, and to determine morphologic
,;].' | '|'l' ' ซ | ,'l|' .|||iJ|| I I ., , . .|||||||l[ jfjll i 'I , 'HyUllf' |,,| ,,] , , i ,,,, , ,, , , , *? ,, , , , , ,, , , ,, ,, , , , i, || f- "... . M| , ,1
evolution o| gullies. Natural drainage patterns can be determined using before and after maps
and profiles, aerial photography, site mining history information and water quality data.
Determinations should also consider precipitation frequency, duration, and intensity. This
information can be used to indicate locations where the implementation of sediment control
BMPs will be most effective.
"ftiil '"
I'll! I!'1'1'
In addition to determining sedimentation patterns, it is important to determine the quantity of
, , , ,, , , i,
sedimentation that can be expected. An estimate of sediment erosion and deposition can be
derived over time using water samples, sediment traps or sediment accumulation markers.
Empirical equations also can be used to estimate the potential for and expected rate of erosion.
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^fhe Universal Soil Loss Equation (USLJB) was developed as a means to predict sediment loss
from watersheds and can be used to estimate sediment yield produced by rill or sheet erosion in
field areas. A Revised Universal Soil Loss Equation (RUSLE) was developed to estimate
quantities of soil that can be lost due to erosion in larger, steeply sloped areas. Predicted soil loss
is calculated using the following equation (OSMRE, 1998, PA DEP, 1999, Renard and others,
1997): '
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Coal Remining BMP Guidance Manual
A = RKLSCP
Where:
A = Computed Soil Loss (Annual Soil Loss as tons/acre/year)
R = Climatic Erosivity or Rainfall erosion index - a measure of the erosive
force and intensity of a specific rainfall or the normal yearly rainfall for
specific climatic regions
K = Soil Erodibility Factor - Ability of soils to resist erosive energy of rain.
A measure of the erosion potential for a specific soil type based on
inherent physical properties (particle size, organic matter, aggregate
stability, permeability). Soils with a K value of 0.17 or less are
considered slightly credible, and those with a K value of 0.45 or higher
are highly erodible. Soils in disturbed areas can be more easily eroded
regardless of the listed K value for the soil type because the structure
has been changed.
LS = Steepness Factor - Combination factor for slope length and gradient
C = Cover and Management Factor - Type of vegetation and cover. The
ratio of soil loss from a field with specific cropping relative to that from
the fallow condition on which the factor K is evaluated.
P = Support Practice - Erosion control practice factor, the ratio of soil loss
under specified management practices.
RUSLE can be used to predict soil loss from areas that have been subjected to a full spectrum of
land manipulation and reclamation activities and has been designed to accommodate undisturbed
soil, spoil, and soil-substitute material, percent rock cover, random surface roughness, mulches,
vegetation types, and mechanical equipment effects on soil roughness, hillslope shape, and
surface manipulation including contour furrows, terraces, and strips of close-growing vegetation
and buffers. It is important to note that RUSLE estimates soil loss caused by raindrop impact
and overland flow in addition to rill erosion, but does not estimate gully or stream-channel
erosion.
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To establish successful vegetation, the soil loss rate should be minimized. Keeping the soil loss
rate below 15 tons/acre for the first year after reclamation should, if surface water controls are
included, allow the establishment of successful vegetation (PA DEP, 1999). For successful
establishment of vegetative cover on abandoned mine land or redisturbed surfaces, the addition
of soil amendments (e.g., soil substitutes, biosolids, etc.) may be necessary. Following
I
regrading, final texture samples should be taken at a rate appropriate for site representation and
i'-jit ! .; i-' lir '111. ';; ' :,; " ^ " ,:' l . :: .. .-!! ',; ,'.>:,; si" ;,; ,',.:< .| ;
analyzed for: pH, acid-base account, and fertility ratings for phosphorous, potassium, nitrogen,
I!
and magnesium. The necessity of amendments such as limestone, nitrogen, available
"* |B i^1 ' j ' "t " \ 'n 1^1 , ' ',"'!!, |, , , ' '' '' ! ' ,' " ," ,' " 1, !,,' , ,' i
ishosphorous (PjjOs), and potash (K,O) can be determined from these analytical results.
i
Additional analyses that can be performed for further determination of site characteristics
i
include: percent sand, silt and clay, textural classification, and water-holding capacity. This
information can be used to assist in determination of the extent of final grading, cover
preparation, and soil water retention amendments that-should be implemented or added.
1.3.1 Implementation Guidelines
The intention of BMPs for control of sedimentation is to minimize erosion caused by wind and
water. A remining sediment control plan should demonstrate that all exposed or disturbed areas
" ' '' "' ;l|'!:! !! :;:"":|"! '" '' "" ' " ' " '"""' :|1" '"" "'" |'
are stabilized to. the greatest extent possible. Operational BMP measures that can be
li ',: . , Mill*.'.. !!l|'i|l!'l ' ' ','ii 'I' ', M . '! I ', " '! ''!'!, , ' , 'If,'!, ป ' ' ir ' I ",' ' i ' Im ,| ' '.| ! '
implemented with this intent include:
Disturbing the smallest practicable area at any one time during the remining operation,
Implementing progressive backfilling, grading, and prompt revegetation,
Stabilizing all exposed surface areas,
Stabilizing backfill material to control the rate and volume of runoff,
Diverting runoff from undisturbed lands away from or through disturbed areas using
protected channels or pipes, and
Using terraces, check dams, dugout ponds, straw dikes, rip rap, mulch, and other
measpr^l"to control overland flow velocity and volume, trap sediment in runoff or protect
the disturbed land surface from erosion (e.g. silt fences and vegetative sediment filters).
., nf"! '; , ,.',', i , . , ,:, , .1 ,;; " , ' '",', j " ; '-: ' 'ซ;.&>' \\
. - > | . , i i
1.1-72 . . r Hydrologic Controls
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Coal Remining BMP Guidance Manual
Construction of terraces, diversion ditches, and other grading/drainage control measures can be
utilized to help prevent erosion and ensure slope stability. It is recommended that drainage
ditches, spillways or channels are designed to be non-erodible, to carry sustained flows, or, if
sustained flows are not expected, to be earth or grass-lined and designed to carry short-term,
periodic flows at non-erosive velocities. Design should demonstrate that erosion will be
controlled, deepening or enlargement of stream channels will be prevented, and disturbance of
the hydrologic balance will be minimal. All slopes and exposed highwalls should be stable and
protected against surface erosion. Slopes and highwall faces should be vegetated, rip rapped, or
otherwise stabilized. Hydrologic diversions and flow controls should be free of sod, large roots,
frozen soil and acid- or toxic-forming coal processing waste, and should be compacted properly
according to applicable regulatory standards. Additional contributions of sediment to streamflow
and runoff outside the permit area should be prevented to the greatest extent possible.
Certain sediment control BMPs already are an integral part of mining operations and do not
require additional engineering designs or construction. These BMPs are recommended for
implementation during pre-, active and post-remining activities, and often are incorporated into
remining BMP implementation plans (Appendix A, EPA Remining Database, 1999). These
BMPs include:
Streams, channels, checks dams, diversion ditches, and drains should be inspected
regularly and accumulated sediment removed. Channels and ditches should be seeded and
mulched immediately after completion, if completion corresponds to regional growing
seasons.
Backfilling and regrading should be concurrent with coal removal and should follow
removal as soon as is technically feasible. Final grading should be performed during
normal seeding seasons to eliminate spoil piles and depressions at a time expeditious for
prompt establishment of vegetation.
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Coal Rdmining BMP Guidance Manual
Exposed and rounded surfaces should be mulched and vegetated immediately following
flna| grading. It is recommended that mulch be anchored in the topsoil and that
vegetation be planted immediately after topsoil grading.
IS1!"!,'
I;!:
M4II', ill :'!'
Areas should be reclaimed to an appropriate grade (slopes should not exceed the angle of
repose or the slope necessary to achieve minimum long-term stability and prevent slides)
to prevent surface-water impounding and promote drainage and stability. All final
grading should be completed along the contour. Terrace-type backfilling and grading
:'. ''1m -Si! r ,'"'i . ;:i ! ' ( -1",: , '.,!': k" fv ": .;',! :::i> '^ rlci1 " .1 ' i^t ,;"'V i; '> "''&.'. < ' .... /!.'
iivoirks to prevent slides and sedimentation while promoting slope stability (this also
maximizes coal recovery and eliminates exposed highwalls and spoil piles).
Unstable-abandoned spoil and highwalls should be eliminated to the greatest extent
possible Care should be taken if the renaming operation requires disturbance of existing
benches and highwalls that have well-established vegetation and drainage patterns. Re-
|
affecting abandoned mine lands that are well-vegetated and stabilized should be avoided
Ait :!!-:ili :: , ' ' :. " ! , - .: : : I , . . I ' ',...! j: ปt Ji '.> '.:i ,; t , ill |;-. V 5 f, : ' * '. i ,.
to the greatest extent possible.
Overburden and topsoil stockpiles that are not being used for topsoil or the establishment
of vegetation should be located to minimize exposure and should be seeded with annual
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Coal Remining BMP Guidance Manual
Site Stabilization
Minimization of the amount of disturbance during remining operations will decrease the amount
of soil and sediment eroding from the site, and can decrease the amount of additional controls or
BMPs that will be required. Operations should only disturb portions of the site necessary for
coal recovery. Operations also can be staged to ensure that only a small portion of the site is
disturbed at any given time. If possible, portions should be renamed, regraded and seeded prior to
disturbance of the next area.
Preserving existing vegetation or revegetating disturbed soil as soon as possible after disturbance
is the most effective way to control erosion (EPA, 1992). Vegetative and other site stabilization
practices can be either temporary or permanent. Temporary controls provide a cover for exposed
or disturbed areas for short periods of time or until permanent erosion controls are established.
Erosion and sedimentation can be minimized by removing as little overburden or topsoil as
possible during remining operations, and by having sediment controls in place before operations
begin. Any possible preservation of natural vegetation should be planned before site disturbance
begins. The advantages of such preservation include the capacity for natural vegetation to handle
higher quantities of surface water runoff.
Revegetation
Revegetation can be one of the most effective BMPs for achieving erosion control. By
functioning to shield surfaces from precipitation, attenuate surface water runoff velocity, hold
soil particles in place and maintain the soil's capacity to absorb water while preventing deeper
infiltration, the establishment of vegetation can stabilize disturbed areas with respect to erosion,
and surface water infiltration, and attenuate AMD formation. Implementation of revegetation
consists of seedbed preparation, fertilizing, liming, seeding, mulching, and maintenance.
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Coal Re'mining BMP Guidance Manual
Biosolids are a low-cost alternative to the use of commercially available lime and fertilizers. The
biosolids typically used on remining sites are sewage treatment sludge. However, other biosolids
can be obtained from paper mill waste arid from other industries! Biosolids are available in
various forms, but the most common is anaerobically digested materials that require an additional
lime amendment.
, * i,
Abandoned mine lands frequently have large areas with little or no topsoil, devoid of organic
|T, T, j ' ,.ii , . .MI,' ,; "liil^. |h 'liiil'HIIll | '!' ' i. ,i ii| . i i v ' ii ii, i |, h'.|.|nni|. mi *. ii r ." ii |. inn."' ill
matter, and micro-organisms. Biosolids use is beneficial in terms of creating a soil substitute and
improving revegetation, but also in developing soil structure through the addition of organic
matter which will foster a microbial community needed for the decomposition of biomass and
other biochemical activities that take place in soil.
F ' ' "i '" ':'/- . ;." V .*;. 'lhf i! I "^.i r; !'.,.'V!!*:*'1
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Vegetative cover can be grass, trees or shrubs, but grasses are the most frequently used because
they grow quickly, providing erosion protection sometimes within days. Permanent seeding and
planting is appropriate for any graded or cleared area where long-lived plant cover is desired, and
is especially effective in areas where soils may be unstable because of soil texture and structure, a
high water table, high winds, or steep slopes.
Typical implementation and maintenance of revegetation operations at 51 mining sites in
Alabama, Kentucky, Pennsylvania, Tennessee, Virginia, and West Virginia, are summarized in
Table l.S.la.
-" ;
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Table 1.3.1a: Revegetation Practices and Maintenance (Appendix A, EPA Remining
Database, 1999)
Revegetation Plan
Systematic sample collection and analysis of topsoil, subsoil, and overburden materials to
determine the type and amount of soil amendments necessary to maintain vegetative growth.
Topsoil placement and seeding occur no later than the first period of favorable planting after
backfilling and grading. Disturbed areas are seeded/planted as contemporaneously as
practicable with completion of backfilling and grading. Backfilled areas prepared for seeding
during adverse climatic conditions are seeded with an appropriate temporary cover until
permanent cover is established (cover of small grain, grasses, or legumes can be installed until
a permanent cover is established).
Disturbed areas are seeded in such a manner as to stabilize erosion and establish a diverse,
effective and permanent vegetative cover, preferably of a native seasonal variety or species
that supports the approved post-mining land use.
Regraded areas are disced prior to application of fertilizer, lime and seed mixture. Fertilizer
mixture is applied as determined necessary by soil sample analyses. Treatment to neutralize
soil acidity is performed by adding agricultural grade lime at a rate determined by soil tests.
Neutralizes are applied immediately after regrading. A minimum pH of 5.5 is maintained.
Mulch is applied to promote germination, control erosion, increase moisture retention, insulate
against solar heat, and supply additional organic matter. Straw, hay, or wood .fiber mulch are
applied at approximately 1.0 to 2.5 tons/acre. Small cereal grains have been used in lieu of
mulch (small grains absorb moisture and act as a soil stabilizer and protective cover until a
suitable growing season).
Conventional equipment is used: broadcast spreader, hay blower, hydroseeder, discs, cyclone
spreaders, grain drills, or hand broadcasting. Excess compaction is prevented by using only
tracked equipment. Rubber tired vehicles are kept off reconstructed seedbeds.
Maintenance
Vegetative cover is inspected regularly. Areas are checked and maintained until permanent
cover is satisfactory. Bare spots are reseeded, and nutrients are added to improve growth and
coverage. Areas that are damaged due to abnormal weather conditions, disease, or pests are
repaired.
Unwanted rills and gullies are repaired with soil material. If necessary, the area is scarified
and (in severe cases) back-bladed before reseeding and mulching.
Revegetation success is determined by systematic sampling, typically at a minimum of 1
percent of the area. Aerial photography can be used to determine success (typically at the 1
percent level - or higher if necessary). Standard of Success (SOS) for revegetation is based on
percent of existing ground cover or achievement of vegetation adequate to control erosion.
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Therefore, the ability to spread biosolids from a secure distance makes it ideal for direct
revegetation application. Biosolids, in many cases, form the basis of soil material or augment
what little soil exists on the site.
Biosolids were used at numerous remining sites in Pennsylvania where little soil existed prior to
remining or where, if soil did exist, it was lost due to burial or erosion from pre-SMCRA mining.
Increases in plant growth and density can be dramatically improved using biosolids.
Channel, Ditch and Gully Stabilization
Stabilization of channels, ditches, and gullies at remining sites, whether constructed for surface
water and erosion control or unwanted, is imperative for controlling sedimentation. In general,
formation of unwanted gullies should be avoided. These BMPs are recommended when
vegetative stabilization practices are not practical and where stream banks are subject to heavy
erosion from increased flows or disturbances. If unwanted or naturally-formed gullies are well-
established, stabilization may prove more effective than removal. Gullies that are deeper than
nine inches may form in regraded areas and should be filled, graded, and reseeded. Rills or
gullies of lesser size may have a disruptive effect on post-mining land use or may add to erosion
and sedimentation and should be filled, graded, and seeded (Appendix A, EPA Remining
Database, 1999VA(2)).
It is recommended that permanent channels and gullies be designed and constructed based on
100 year, 24 hour storm event. Channels and gullies can be stabilized and protected from
eroding forces by the implementation of linings and/or check dams. Linings can be constructed
of grass, rock, rip rap, or concrete. Check dams can be constructed with staked straw bales,
wood, or rock. Although channel linings and check dams can trap small amounts of sediment,
their primary purpose is to reduce the velocity of storm water flow, thus abating additional
erosion.
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Channel Linings
:>!'!>i 'i-H-
Erosion is a serious problem associated with channels and other water control structures.
Sediment loads from eroded channels can cause numerous sediment and hydraulic problems and
decrease the effectiveness of other sediment control measures. Depending on flow velocities,
channel linings may be required to prevent channel erosion (MD DNR, 1989).
Due to the ease of construction and low cost, a vegetated channel lining is one of the most cost-
,;,:;;;;, ;-- ;,.. . V .; ; .. ; ,, . . , , ;; ; ; _ , , ~-,\; ,, , ;;;.- , ;;;
effective ways of reducing channel erosion and is frequently used on diversion ditches. A well-
established grass can protect the channel from erosive flow velocities of up to 6 feet per second
(fjps). Shorter meadow-type grasses with short, flexible blades can withstand a maximum velocity
of 5 fps. Bunch grasses or sparse cover provides only marginally better erosion protection than a
well constructed earthen channel. For prevention of erosion, the Commonwealth of Kentucky
(Kentucky,1996) recommends mat channels having a peak discharge design velocity of less than
5 fps be lined with grass species that are effective against erosion (e.g. Tall Fescue, Reed
Canarygrass, Bermudagrass, and Kentucky Bluegrass). Channels having discharge velocities of
3 fps or greater should be lined with rip rap or other non-erodible, non-degradable materials
unless the ditch is located in solid rock. Pennsylvania DEP (PA DEP, 1999) recommends a
I
maximum velocity of 3 fps if only sparse cover can be established(because of shale, soils, or
climate); a velocity of 3 to 4 fps if the vegetation is established by seeding (under normal
conditions); and a velocity of 4 to 5 fps only in areas where a dense, vigorous sod is obtained
quickly or if runoff can be diverted out of the waterway while vegetation is being established.
i
Vegetative linings typically begin eroding the base of channels, and once started, will continue
until an erosion resistant layer is encountered. If it becomes evident that erosion of a channel
bottom is occurring, rock or stone rip rap lining should be placed in the eroded areas. Rip rap
lining should be durable and should be free of acid-forming materials. Generally, rip rap
composed of varying sizes of stones is preferred over rip rap that is uniform, not only because it
is less expensive, but because varying stone size promotes natural settling and grading to form a
1-80
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Coal Remining BMP Guidance Manual
better seal. In addition, rectangularly shaped stone is preferred for its durability. Smooth or
rounded stones should not be used (MD DNR, 1989). A good recommendation is the use of a
well-graded mixture down to the one-inch particle size such that 50 percent of the mixture by
weight is no larger than the median stone size. Rip rap layers should have a minimum thickness
of 1.5 times the maximum stone diameter or no less than six inches, whichever is the lesser
value. Channel banks should be protected to a height equal to the maximum depth of flow
(Kentucky, 1996). Rip rap used in diversion ditches and pond spillways should consist of
durable sandstone or limestone exhibiting a Slake-Durability Index of 85 or greater. The rip rap
should be well-graded with the maximum stone size D(100) equal to the blanket thickness and
the median stone size DD(50) equal to one half the blanket thickness (Appendix A, EPA
Remining Database, 1999 VA(7)).
Check Dams
The purpose of check dams is to reduce the velocity of concentrated surface-water flow until
diversion ditches or gullies are properly vegetated. Check dams can be constructed of straw
bales, logs, rocks (Figure 1.3.la), or other readily available materials, and should be designed so
that water crosses only through a weir or other outlet and never flows along the top or the outside
of the dam (Kentucky, 1996). The distance between check dams varies depending on the slope,
with a closer spacing when slopes are steeper. Materials used should be relatively impermeable
and of appropriate size, angularity, and density. They should be contained in anchored wire mesh
or gabions, or staked to prevent flowing water from transporting them (Figure l.S.lb).
The material used depends on the size and type of flow that is expected. Straw bale check dams
generally are suitable for sediment control where concentrated flows do not develop. The
efficiency of straw bale dams is limited by slope length and gradient. Straw or hay bales should
be secured with stakes. Log check dams can be used in channels and generally are more effective
and stable than straw bale barriers. It is recommended that logs be four to six inches in diameter,
driven sufficiently beneath the channel floor, and stand perpendicular to the plane of the channel
cross section, with no space between logs (Kentucky, 1996). It also is recommended that rip rap
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or shorter, wider logs on the downstream side be installed for stability. Rock check dams and
straw bales allow water to pass through, controlling sediment movement through filtration and
flow control. The size of the stone used in a rock check darn varies, with rock size increasing as
flow velocity and discharge volume increase. For most rock check dams, the National Crushed
Stone Association no. R-4 stone (3 to 12 inches, 6 inch average) is a suitable stone size (PA
DEP, 1999). Filter stone applied to the upstream face of check dams can improve sediment
trapping efficiency. Regular removal of sediment that accumulates behind the check dam is
imperative for maintenance of efficiency, control of surface water flow, and avoidance of
worsening conditions. Check dams also can be built in series, as necessary.
IS'
'"
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Figure 1.3.1a: Example of a Rock Check Dam (Kentucky, 1996)
III ' . ',' ,, :' !'ii,i " llii !" , ' '', . Jl ' : ' ' '' " I I
':, li ., >:! ill,..!!
Instreara view
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Figure 1.3.1b:
Example of a Gabion Check Dam (Kentucky, 1996)
Silt Fences
Silt fences are used as temporary sediment barriers and are commonly constructed of burlap or
synthetic materials stretched between and attached to supporting posts. The purpose of silt
fencing is to detain sediment-laden, overland (sheet) flow long enough to allow^the larger size
particles to settle out and to filter out silt-sized particles. Because the screen sizes of synthetic
screen fences will vary according to the manufacturer, these fences usually do not have the
strength to support impounded water and are limited to control of overland runoff. Common
problems associated with silt or filter fabric fences usually result from inappropriate installation
such as placement in areas of concentrated flows or steep slopes and placement down rather than
along contours. These fences work best when placed on areas with zero slope. Because this
often is not possible, flow should be otherwise reduced by the downslope emplacement of hay
bales, mulching, or breaking the length of installation into separate sections that will not allow
significant flow volumes. Silt fencing is appropriate for sediment control immediately upstream
of the point(s) of runoff discharge, before a flow becomes concentrated, or below disturbed areas
where runoff may occur in the form of overland flow.
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Gradient Terraces
Gradient terraces can be used to control slope lengths, minimize sediment movement, and, on a
site-specific basis, to address particular erosion problem spots according to need. Terraces are
typically earth embankments or ridge-and-channels constructed along the face of a slope at
ii
regular intervals and at a positive grade. These BMPs often help stabilize steeply sloped areas
until vegetation can be established and reduce erosion damage by capturing surface runoff and
directing it to a stable outlet at a speed necessary to minimize erosion. Terrace locations and
spacing can be determined following general grading and location of problem areas. It is
recommended that terraces constructed on slopes are not excessive in width and have outer
slopes no greater than 50 percent.
^Design Criteria
General
Design should approximate natural drainage as closely as possible.
Sediment-control structures should be chosen according to review of existing topography,
flow direction and volume, outlet location, and feasibility of construction.
Sediment control structures should be constructed on stable ground.
"' Use of costly earth-moving equipment should be minimized.
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Weathered, vegetated and highly established portions of landscape should be preserved to
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the greatest extent possible.
Revegetation
Volunteer, natural vegetation should be encouraged, and where possible, undisturbed.
Channel. Ditch and Gully Stabilization
ฃ Liner materials should not contain acid-forming materials.
IS! i
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Stabilization should be supported properly. Potential for stream bottom and sides to erode
should be considered.
Vegetation-lined ditches should be limited to velocities of 4 to 5 fps, unless
documentation is provided that runoff will be diverted elsewhere while vegetation is
being established.
Permanent structures should be designed to handle expected flood conditions.
Check Dams
Should be used only in small open channels which will not be overtopped by flow once
the dams are constructed.
Check dams should be anchored to prevent failure.
Dams should be sized according to projected flows.
The center of the dam should be lower than the edges.
Straws bale barriers should be placed at zero percent grade, with the ends extended up the
side slopes so that all runoff above the barrier is contained in the barrier.
Stones should be placed by hand or using appropriate machinery, and should not be
dumped in place.
Silt Fences
Support posts should be strong and durable.
Filter material should be able to retain at least 75 percent of the sediment.
Fences should be installed in undisturbed ground, and stability should be reinforced with
rope or rip rap.
Adjoining sections of filter fabric should be overlapped and folded.
Bottom edge should be tied or anchored into the ground to prevent underflow.
Maintenance should be performed as needed, and material replaced when bulges or tears
develop.
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ijjCtjo/ Remitting BMP Guidance Manual
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Terraces
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Terraces, in general, should not be excessive in width or have outer slopes greater than 50
percent.
Utilize diversion ditches as necessary, while a vegetative cover is being established.
Terraces should be designed with adequate outlets, such as a grassed waterway or
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vegetated area, to direct runoff to a point not causing additional erosion.
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1.3.2 Verification of Success or Failure
Implementation Checklist
Revegetation
Vegetation should be maintained through cutting, fertilizing and reseeding if needed.
Vegetative success should be determined by a systematic sampling and plant count, and if
" 'necessary, aerial photography. Success should be measured on the basis of adequate
vegetative cover which shall be defined as a vegetative cover capable of self-regeneration
8nd plant succession, and sufficient to control soil erosion.
i
Established vegetation should be inspected periodically for scouring. Scoured areas
should be reseeded immediately.
I
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Channel. Ditch and Gully Stabilization
III I II I 111 I I III , '4 '"' ',;;' '', jj, j,,^ Ji n iซ. :,<;
* Inspect regularly and after each major storm event for: sediment buildup, scouring,
blockage and lining damage or movement.
I
If excessive scouring or erosion occurs in ditches or channels, they should be lined with
rock rip rap or netting immediately.
ป Sediment build up usually occurs in areas of low-flow velocities allowing particles to
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settle. Grade should be checked in these areas since low-flow velocities may mean the
channel is undersized.
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Coal Remining BMP Guidance Manual
Rip rap stones that have moved should be replaced and the rip rap fortified if
undercutting has occurred.
Check Dams
Inspect check dams regularly and after significant precipitation events for damage and
sediment accumulation.
Accumulated sediment should be removed from behind the dams and erosive damage
restored after each storm or when half the original dam height is reached.
The length of straw bale barriers should be inspected on a periodic basis to look for
problem areas. Eroded areas should be regraded, accumulated sediment removed, and the
barrier repaired to maintain effectiveness.
Stone should be replaced as necessary to maintain correct dam height.
Silt Fences
Silt fences should be inspected daily during periods of prolonged rainfall, immediately
after each rainfall event, and weekly during periods of no rainfall.
Required repairs should be made immediately.
Sediment should be removed once it reaches one-third to one-half the height of the filter
fence.
Filter fences should not be removed until the upslope area has been permanently
stabilized. Sediment deposits remaining after the filter fence has been removed should be
graded, prepared and seeded.
Terraces
Terraces should be inspected regularly at least once a year and after major storms.
Proper vegetation and stabilization practices should be implemented during construction.
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1.3.3 Literature Review / Case Studies
Case Study 1 (Harper and Olyphant, 1993; Olyphant and Harper, 1995; Carlson and Olyphant,
1996)
NIL. { Dill, "''linill:
Direct Revegetation
Coal refuse is often an acid-forming material containing high concentrations of pyrite (ป 0.50
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percent total sulfur). If present, the oxidation of pyrite causes acidification of the soil, and
acidification in turn, greatly inhibits vegetation. Substantial erosion and sedimentation occur due
. ':": ,.' "";"" ::. ",".',, :,..' , "!"" -' : ':";- - ":
to poor or complete lack of vegetation on abandoned surface mine lands and coal refuse piles.
Erosion is further accelerated by steep slopes common to some abandoned mine sites. Olyphant
111 n I Mil I I I III III II nil -'I''1!"! 5,,,, ป r -V 11,,- v "- -N
and Harper (1995) observed that direct revegetation of abandoned pyritic coal refuse piles can
successfully reduce the sediment load as well as improve the water quality of the runoff effluent
from abandoned mine lands.
Direct revegetation was conducted on abandoned pre-SMCRA coal refuse piles located in
Sullivan County, Indiana (Harper and Olyphant, 1993; Olypharit arid Harper^ 1995; and Carlson
and Olyphant, 1996). Prior to revegetation, these piles were characterized by "severe and rapid
erosion" and high pyritic content (up to 4.4 percent by weight). The colluvial material "derived
from, gully side slopes" built up through the winter months. This material was washed out during
th"e spring followed by "erosional downcutting" through the summer and fall. Yearly
backcutting of the gullies ranged from 2.5 to 4.6 centimeters with an interfluve lowering of 0.4
centimeters. The volume of sediment yielded by these gullies was approximately four fold that
Of the watershed as a whole and about 10 times that of adjacent interfluve areas. Yearly
sedimentation yield was over 10 kg/m2 (Olyphant and Harper, 1995).
In order to treat the acidity of the surficial refuse and allow plant growth, limestone was directly
disced into the refuse without regrading the existing surface. Fertilizer was also broadcast over
portions of the site to promote the vegetative cover. Additionally, small rip rap check dams and
water bars \vere installed to prevent erosion and promote infiltration of precipitation. From 1990
1-88
Hydrologic Controls
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Coal Remining BMP Guidance Manual
to 1992, 100 to 210 tons per acre of agricultural limestone was disced to a depth of 6 inches into
the refuse. Fertilizer was applied in the spring of 1991 and 1992 at rates of 100 Ibs per acre of
N2, 150 Ibs per acre of P2O2, and 350 Ibs per acre of K2O. The refuse was initially planted with a
rye-nurse crop. Additionally, a permanent cover of Kentucky 31 fescue, bristly locust, and black
locust was highly successful. Direct vegetation of weathered, undisturbed refuse with a pH less
than 3.8 and pyrite concentrations less than 0.84 percent, resulted in successful stabilization
(Harper and Olyphant, 1993). Within 18 months, the site had a diverse dense growth of planted
and volunteer vegetation (Olyphant and Harper, 1995).
The rip rap check dams were installed by "end-dumping" between 5 and 185 tons of rock directly
into the upper parts of erosion gullies. Erosion netting and water bars were also used to control
erosion on steep-slope areas, where additional time and effort is required to achieve sufficient
vegetative cover to inhibit erosion.
The remedial work (direct planting, check dams, and water bars) resulted in increased
precipitation infiltration (decreased runoff), reduced erosion and sedimentation, and an
improvement in the runoff-water quality. Runoff decreased by 56.7 percent, from 30 to 13
percent of the precipitation. The increased infiltration resulted in a higher moisture content in the
root zone, especially during dry periods. Coarse sediment yield prior to vegetation and the
implementation of sediment controls comprised more that 50 percent of the total sediment.
Afterward, coarse-grained sediments were virtually nonexistent. Fine-grained sediments
declined from 4.5 kg/m2 to 0.3 kg/m2, or 93.3 percent. The acidity of the runoff improved from
being occasionally over 700 mg/L to an average alkalinity of 75 mg/L (Olyphant and Harper,
1995). However, no alkalinity was observed in the refuse pore water below a depth of 1.7 feet
(Harper and Olyphant, 1993).
Case Study 2 - Keel Branch, VA (Zipper and others, 1992)
The study area was an abandoned surface and underground coal mining site in Dickenson
County, Virginia. The surface mining occurred between 1955 and 1958. "Shoot and shove"
mining operations of that period produced a terrain consisting of exposed highwalls, more or less
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'Coal Remining BMP Guidance Manual
level benches, and steep spoiled outslopes. Abandoned mine land areas included approximately
i
170 acres and 8,000 linear feet of outslope-bench-highwall terrain. Highwalls from 50 to 100
feet high remained easily visible with evidence of some sloughing of highwall materials.
Vegetative cover of the benches varied from dense to barren. The barren areas are associated
\Vith "bum out" from acidic coal fines. The outslopes were the main source of major
environmental problems, with surface inclinations commonly exceeding 30ฐ and extremely
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Sloped areas nearing 40ฐ. Adverse environmental impacts on watershed soil anil vegetation was
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verified by the deterioration of natural forest areas directly below outslopes, caused by sediment
Jnovement from higher elevations downward toward the stream. A mining company was
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Interested in remining coal from abandoned deep mine pillars and solid-coal sections that had not
been surface mined, but was concerned about environmental liabilities (Zipper and others, 1992).
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The goal of the study was to identify and compare the environmental effects of four remining and
reclamation options. The objective was to estimate the reduction in soil loss and sediment yield
likely to be achieved by various remining and reclamation strategies, relative to existing
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conditions using a modified Universal Soil Loss Equation model in a Geographic Information
System (GIS) environment. The study evaluated three remining options and one AML-funded
reclamation option and compared them to a "do-nothing" strategy. The remining options
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Considered were:
Remnant Recovery: a technique frequently used to mine the remaining coal reserves from
abandoned bench-highwall-outslope terrain in southwestern Virginia, eastern Kentucky and
southern West Virginia. The mine operator employs conventional second-cut remining, taking
an additional cut from the highwall to extract coal from the most profitable areas. Sipoil from trie
second-cut is used to reclaim the exposed highwall segment to the maximum extent technically
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practical. The reclaimed site is characterized as a steeply sloped highwall backfill, which may be
adjacent to exposed highwalls remaining from unreclaimed pre-SMCRA operations. Existing
spoil hi the putslope areas is not re-affected (Zipper and others, 1992).
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Coal Remining BMP Guidance Manual
Conventional Second-Cut Contour: is also commonly used in steeply-sloped Appalachian areas
and similar to remnant recovery, except rather than mining only the most profitable areas,
additional cuts are taken from a relatively long, continuous portion of the highwall. This method
also allows for reclamation of all exposed highwall to steeply sloped backfill contours. As with
remnant recovery, outslope spoils are avoided to the greatest extent possible (Zipper and others,
1992).
Innovative Remining: designed to maximize reclamation effectiveness as allowed by the scope
of the remaining minable coal reserves. The key to this plan is to apply virgin cuts to a coal seam
at the base of the spoil slope as well as additional cuts into the existing highwall of a higher coal
seam. In the process of reclamation, the spoil on the outslope will be eliminated. Critical to this
plan is that the highest portions of the upper highwall do not have to be completely reclaimed.
This is important because such reclamation can be cost prohibitive for remining
operations. Much of the temporary sediment controls are placed down gradient in or near the
headwaters of the adjacent streams. The main benefit of this methodology is that the problems
caused by the spoil outslopes are eliminated (Zipper and others, 1992).
AML Reclamation: an option in which no additional coal is mined, the outslope area is regraded
and the spoil is replaced into the existing open pit. Complete highwall elimination is unlikely,
because the amount of spoil on the outslope is insufficient. However, the exposed strip bench is
covered. Actual AML reclamation is unlikely at the study site because is has been assigned the
lowest AML Fund priority number (3) (Zipper and others, 1992).
Roughly 40 percent of the abandoned mined areas of the site (mainly the steep outslopes)
presently yield 95 percent of the sediment. Most of the study area (77 percent) has estimated soil
losses of "stable conditions", which are 0 to 1 ton per year. Approximately 8 percent of the AML
area has soil loss potentials of between 20 and 50 tons per year. Soil losses exceeding 50 tons
per year were determined for 2.6 percent of the AML area. Of the total soil loss, 60 percent was
redeposited on the land surface, while the remaining 40 percent caused siltation of the streams.
Hydrologic Controls
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Coal Remining BMP Guidance Manual
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Remnant recovery and conventional second-cut contour were determined to be the least effective
reclamation techniques in terms of controlling erosion and sedimentation. Remnant recovery
showed a soil loss reduction of 8 to 23 percent depending on the amount of vegetative cover of
_ _, ^ _cฃ respectiveiy Conventional second-cut contour faired slightly higher with soil
r 'i:' ' * ' ' - "||
loss reductions of 19 to 39 percent. The two reclamation methods that eliminate the outslope
SDoil performed the best. Innovative renaming has predicted soil loss reductions ranging from 38
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to 86 percent, while AML reclamation would yield soil loss reductions from 52 to 75 percent.
Regardless of the reclamation technique analyzed the effectiveness improved with increasing
ground cover (Zipper and others, 1992).
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resource is utilized, and substantial reclamation is achieved.
1.3.4 Discussion
Typical sedimentation control BMPs entail slope regrading, revegetation, sediment trapping, and
control of runoff. Successful control of erosion and sedimentation from renaming operations may
require innovative practices and controls in addition to those normally implemented. Existing
unreclaimel conditions create distinct problems, especially in terais of erosion and sedimentation
on steeply sloped spoil. Innovative techniques for renaming and reclamation can be employed to
,'",; \' ,'"',', '!" ',"'""I """"'!""!' " , !' , ' !, ' ',' ' ""!,'"" "!" ' ',' '"!'!"', ', ', ' '"!!, ' ' " '!!!'" ' ' ,1' !'
mitigate erosion and sedimentation problems.
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Benefits
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Implementation can require minimal labor. Sediment control BMPs are typically low cost
i
and use conventional farming equipment.
Can subsequently reduce availability or reactivity of acid-forming materials.
Can subsequently be implemented to control site surface-water hydrology.
Hydraulic and sediment control BMPs are often already permit requirements.
i
' Hydrologic Controls
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Coal Remining BMP Guidance Manual
Biosolids can provide nutrients and organic mater on sites with poor or nonexistent soils,
thus enhancing plant growth.
These BMPs often improve site aesthetics and can provide wildlife habitats.
Limitations
If not designed, implemented, and maintained properly, severe and rapid erosion can
occur as natural drainage networks are re-established.
Steeply sloped areas may require intensive physical labor (not machine accessible).
Establishment of vegetative covering should be coordinated with climatic conditions for
proper establishment.
Biosolids application rates may be limited by metals concentrations.
BMP success is often dependent on climate and weather.
1.3.5 Summary
There are remining situations where the primary water quality concern is not necessarily the
dissolved contaminant or pH, but is instead suspended solids and the subsequent deposition of
sediment into receiving streams. Surface mining prior to SMCRA commonly left unreclaimed
spoil piles and open pits. Pre-SMCRA mining operations in steeply sloped areas tended to spoil
the overburden downslope of the operation. Abandoned spoil piles and exposed surfaces have
been weathering for decades and through natural processes, typically have been partially to
completely revegetated. Whether or not these spoil piles are reaffected, considerable erosion and
sedimentation may result during remining operations. Therefore, erosion and sedimentation
control BMPs frequently require additional measures in addition to the standard controls.
Slope stabilization through control of precipitation runoff is a critical component of these BMP
practices. If erosion can be prevented, sedimentation will be controlled. Runoff and associated
erosion is controlled through the integration of engineered slopes (e.g., terraces), revegetation,
Hyarologic Controls
1-93
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surface-water diversion through or away from spoil areas, sediment traps (.e.g., silt fences, check
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dams, rip rap, dugout ponds), minimizing the amount of unreclaimed land at any given time,
concurrent reclamation, and elimination of existing unstable spoil areas. Although significant
sedimentation associated with remining is somewhat regional and is more prominent in steep
slope areas, me problem is an important one. The BMPs discussed in this section have been
successfully applied throughout the eastern Coalfields.
i
References
Ackman, T. E., 1 R. Jones, and C. C. Hustwit, 1989. Stream Sealing to Reduce Infiltration into
Underground Mines, Final Report, U.S. Bureau of Mines, Interagency Agreement No. J5160066
With the Office of Surface Mining Reclamation and Enforcement, Green Tree, PA, 108 p.
Hi II Ill '.! L i,!1- / '&,.' !.!..i 4, .' IV,,' '., " :, , 'I!!!'1: :. i'1: vli, i ill:!'11:..";-:,!,;1 , ,,^ ' ',ซ ป i
Ackman, T. E. and J. R. Jones, 1988. Stream Sealing to Reduce Surface Water Infiltration,
U.S. Bureau of Mines Information Circular, IC9183, pp. 233-239.
Bell, A. V. j M7 D. Riley, and" E. K. Yanful, 1994. Evaluation of a Composite Cover to
Control Acid Waste Rock Pile Drainage. In the proceedings of International Land Reclamation
and Mine Drainage Conference and Third International Conference on tlie Abatement of Acidic
Drainage, vol 2 of 4, U.S. Bureau of Mines Special Publication SP 06B-94, pp. 113-121.
gqpth, C.J.,1988. Interpretation of Well and Field Data in a Heterogeneous Layered Aquifer
getting, Appalachian Plateau, Ground Water, Vol. 26, No. 5, pp 596-606.
Borchers, IW. and G.G. Wyrick, 1981. Application of Stress-Relief-Fracturing Concepts for
Monitoring me Effects of Surface Mining of Ground Water in Appalachian Plateau Valleys. In
the Proceedings of the Symposium of Surface Mining Hydrology, Sedimentology, and
Reclamation, December 7-11,1981, University of Kentucky, Lexington, K.Y, pp. 443-449.
Broman, P".' G., P. Hagland, and E. Mattsson, 1991. Use of Sludge for Sealing Purposes in
Dry Covers-Development and Field Experiences. In the Proceedings of the Second
International Conference on the Abatement of Acidic Drainage, Montreal, Quebec, Canada,
Tome 1, pp. 515-528.
:"; ';'..'' ': : ::: : : '.".' '.::'''.. : ::' ."."..' j: , ::
Carlson, Christopher P. and Oylphant, Greg A., 1996. The Role of Gully Stabilization in
Abandoned Mine Lands Reclamation. Environmental & Engineering Geoscience, Vol. II, No. 3,
1996, pp. 393-405.
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Coal Remining BMP Guidance Manual
Caruccio, F.T. and G Geidel, 1986. Geologic Factors Affecting Mine Drainage Quality, In the
Proceedings of A One-Day Conference Depositional Environment and Coal Hydrology, Clarion
University, January 23, 1986. pp. 39-48.
Cederstrom, D.J., 1971. Hydrologic Effects of Strip Mining West of Appalachia. Mining
Congress Journal, March, 1971, pp. 46-50.
EPRI, 1981. Coal Ash Disposal Manual, Second Edition, prepared by GAI Consultants, Inc. for
the Electrical Power Research Institute, Palo Alto, CA, Section 2, pp37.
Freeze, R. A. and J. A. Cherry, 1979. GROUND WATER, Prentice-Hall, Inc., Englewood Cliffs
NJ, 604 p.
Gardner, M., 1998. Water Management Techniques on Surface Mining Sites, Chapter 16 of Coal
Mine Drainage Prediction and Pollution Prevention in Pennsylvania, Pennsylvania Department of
Environmental Protection, Harrisburg, PA, lip.
Gerencher, E. H., J. Y. Wong, R. van Dyke, and D. E. Konasewich, 1991. The Use of Mine
Tailings in Concrete Surface Covers to Control Acid Mine Drainage in Waste Rock Dumps. In
the Proceedings of the Second International Conference on the Abatement of Acidic Drainage,
Monteal, Quebec, Canada, Tome 4, pp. 69-84.
Harper, Denver and Olyphant, Greg A, 1993. Direct Revegetation of Abandoned Coal-Refuse
Deposits in Indiana: Its Effects on Hydrology, Chemistry, and Erosion. Final Report to the
Indiana Division of Reclamation Concerning Research and Reclamation Feasibility Studies at the
Friar Tuck Site, Sullivan and Greene Counties, Indiana. Indiana Geological Survey, 41 p
Hawkins, J. W., 1998a. Hydraulic Properties of Surface Mine Spoils of the Northern
Appalachian Plateau. In the proceedings of 25th Anniversary and 15th Annual Meeting of the
American Society for Surface Mining and Reclamation, St. Louis, MO, pp. 32-40.
Hawkins, J. W., 1998b. Hydrogeologic Characteristics of Surface-Mine Spoil, Chapter 3 of Coal
Mine Drainage Prediction and Pollution Prevention in Pennsylvania, PA DEP, Harrisburg, pp. 3-
1 to 3-11.
Hawkins, J. W., 1995a. Impacts on Ground Water Hydrology from Surface Coal Mining in
Northern Appalachia, Proceedings of the 1995 Annual Meeting of the American Institute of
Hydrology, Denver, CO.
Hawkins, J. W., 1995b. Characterization and Effectiveness of Remining Abandoned Coal Mines
in Pennsylvania. U.S. Bureau of Mines, Report of Investigations-9562, 37 p.
Hawkins, J. W., 1994. Modeling of a Reclaimed Surface Coal Mine Spoil Aquifer Using
MODFLOW. In Proceedings of the International Land Reclamation and Mine Drainage
Hydrologic Controls
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PI i l iS ::l "f
Coal Reniining J?A?P Guidance Mtanual
Conference and Third International Conference on the Abatement of Acidic Drainage, Pittsburgh
PA, Vol. 2, pp. 265-272.
Hawkins, J. W. and W. W. Aljoe, 1991. Hydrologic Characteristics of a Surface Mine Spoil
Aquifer. In Proceedings of the Second International Conference on the Abatement of Acidic
Drainage, Montreal, Quebec, Canada, Tome 1, pp. 47-68.
Hawkins, J.W. and! W.W. Aljoe, 1990. Hydrologic Characterization and Modeling of a
Heterogeneous Acid-Producing Surface Coal Mine, Upshur County, West Virginia, In the
Proceedings of the 1990 National Symposium on Mining, May 14-18, 1990, University of
Kentucky, Lexington Kentucky, pp. 43-52.
j
Hawkins, J.W.,K.B.C. Brady, S. Barnes, and A.W. Rose, 1996, Shallow Ground Water Flow in
Unmined Regions of the Northern Appalachian Plateau: Part 1. Physical Characteristics, In the
Proceedings of the Thirteenth Annual Meeting of the American Society for Surface Mining and
Reclamation, Knoxville, TN, pp. 42-51.
Helgeson, J. O. and A. C. Razem, 1980. Preliminary Observation of Surface-Mine Impacts on
Ground Water in Two Small Watersheds in Eastern Ohio. p. 351-360. In Proceedings of the
Symposium of Surface Mining Hydrology, Sedimentology and Reclamation. (Lexington, KY,
December 1-5, 1980). ' "" " ' '." ; [ '"]
HelUer^W'.w'^ "1998. Abatement of Acid Mine Drainage by Capping a Reclaimed Surface Mine ฐ "^
lyith Fluidized Bed Combustion Ash, 'Mine Water &"tKe Environment, Jour, of the International ' "''
Mine Water Assoc!, v. 17, no. 1, pp. 28-40.
Herring, W. C., 1977. Ground Water Re-Establishment in Cast Overburden. In Proceedings of
"the Seventh Symposium on Coal Mine Drainage Research,'Louisville,' KY, pp. 77-87.
II I I II I III II III ' I,,,, ! ,||,' ' ,: ,;'i|, |
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Coal Remining BMP Guidance Manual
Meek, F. A., 1994. Evaluation of Acid Prevention Techniques Used in Surface Mining. In the
Proceedings of International Land Reclamation and Mine Drainage Conference and Third
International Conference on the Abatement of Acidic Drainage, v. 2 of 4, U.S. Bureau of Mines
Special Publication SP 06B-94, pp. 41-48.
Miller, J.T. and D.R. Thompson, 1974. Seepage and Mine Barrier Width, In the Proceedings of
the Fifth Symposium on Coal Mine Drainage Research, National Coal Association, Louisville
KY, pp. 103-127.
Nawrot, J.R., Sandusky, J. and Klimstra, W.B., 1988. Acid soils reclamation: applying the
principles. In: Process Mine Drainage and Surface Mine Reclamation Conf., Pittsburgh, PA,
April 1988. US Bureau of Mines and Office of Surface Mining Reclamation and Enforcement
pp. 93-103.
Olyphant, Greg A. and Harper, Denver. Effects of direct revegetation on the hydrology, erosion
and sediment yield of an abandoned deposit of coal-mine refuse. Geomorphology 11 (1995) pp
261-272.
Office of Surface Mining Guidelines for the Use of the Revised Universal Soil Loss Equation
(RUSLE), Version 1.06 on Mined Land, Construction Sites and Reclaimed Lands, August 1998.
Pennsylvania Department of Environmental Protection, 1998. Coal Mine Drainage Prediction
and Pollution Prevention in Pennsylvania, Brady, K.B.C., M.W. Smith, and J. Schueck, eds.
Pennsylvania Department of Environmental Protection, Bureaus of Mining and Reclamation and
District Mining Operations, Engineering Manual for Mining Operations, 1999.
Potter, K. N., F. S. Carter, and E. C. Doll, 1988. Soil and Water Management and Conservation.
Soil Science Society of America Journal, v. 52. pp. 1435-1438.
Rasmuson, A. and I. Neretnieks, 1986, Radionuclide Transport in Fast Channels in Crystalline
Rock, Water Resources Research, Vol. 22, No. 8, pp. 1247-1256.
Razem, A. C., 1983. Ground Water Hydrology Before, During, and After Coal Strip Mining of a
Small Watershed in Coshocton County, Ohio. U.S. Geological Survey, Water-Resources
Investigation Report 83-4155. Columbus, OH. 36 p.
Razem, A. C., 1984. Ground Water Hydrology and Quality Before and After Strip Mining of a
Small Watershed in Jefferson County, Ohio. U.S. Geological Survey, Water-Resources
Investigation Report 84-4215. Columbus, OH. 39 p.
Renard, K.G., Foster, G.R., Weesies, G.A., McCool, D.K., and Yoder, D.C., 1997. Predicting
Soil Erosion by Water: A Guide to Conservation Planning with the Revised Universal Soil Loss
Equation (RUSLE). USDA, Agriculture Handbook Number 703, 40Ip.
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Guidance Manual
Ml' ' I t ., ,1! I'l
Rogowski, A. S. and H. B. Pionke, 1984. Hydrology and Water Quality on Stripmined Lands.
U.S. Environmental Protection Agency, EPA-IAG-D5-E763, 183 'p.
Silburn, D. M. and F. R. Crow, 1984. Soil Properties of Surface Mined Land. In Transactions of
the ASAE, v. 27. no. 3. St. Joseph, MI, pp. 827-832.
Skousen, J.', R. Hedin, and B. Faulkner, 1997, Water Quality Changes and Costs of Remining in
Pennsylvania and West Virginia, In the Proceedings of the 1997 National Meeting of the
American Society for Surface Mining and Reclamation, Austin, TX, pp. 64-73.
Smith, M. W., 1988. Establishing Baseline Pollution Load from Pre-existing Pollutional
Discharges for Remining in Pennsylvania. Proceedings Mine Drainage and Surface Mine
....... Reclamation Vol.' itt:llline!'1|leciamation, Abandoned' Mine' L''ah(ls' and Policy Issues" U.S. Bureau
Strock, N., 1998. Reclamation and Revegetation, Chapter 12 of Coal Mine Drainage Prediction
arid Pollution Prevention in Pennsylvania. Pennsylvania Dept. of Environmental Protection.
i ii i i i i HIM ii ii i i I7 i:"1!,!!1, ,'/. :'A' '' '' ป:,'Vii'... .!''' : *K'.''?/ii iri.'.i/iiiiiiii,..'"''''i i''"ii|i'::i'b'1|!i|llif'..* ii* *:'' '*'<''
U.S. EPA, Office of Water, Municipal Wastewater Management Fact Sheets Storm Water Best
Management Practices (EPA 832-F-96-001), September 1996.
U.S. EPA, Office of Water, Storm Water Management for Construction Activities, Developing
Pollution Prevention Plans and Best Management Practices (EPA 832-R-92-005), September
"1992. "
::; :: ::::::,' :: :;:,, , , :;.. :::: :;;;:.. =;:;. i ; -:. : : ..r::.:.
U.S. Environmental Research Service, 1998. Engineered Structures for Sealing Underground
Mines, Unpublished report prepared for West Virginia Surface Mine Drainage Task Force.
Weiss, J. S. and A. C. Razem. 1984. Simulation of Ground Water Flow in a Mined Watershed in
Ohlpy^QUND WATER, v. 22, no.5, p.549-560.
|, P?'^.llapd J. 'sTpinger."' 1994. The Hydrogeology arid' MySrogeocrie'mistry" of the Star'""
Fire Sitej Eastern Kentucky, In Proceedings of the International Land Reclamation and Mine
Drainage Conference and Third International Conference on the Abatement of Acidic Drainage,
PA, Vol. 2, pp. 188-197.
tail'
Wyrick, G.G. and J.W. Borchers, 1981. Hydrologic Effects of Stress-Relief Fracturing In and
Appalachian Valley, U.S. Geological Survey Water-Supply Paper 2177, pp. 51.
Yanful, E. K., K C. Aube, M. Woyshner, and L. C. St-Arnaud, I954."Mel|d and Laboratory
Performance of Engineered Covers for the Waite Amulet Tailings, In the Proceedings of
^rnte^a^onal Land^Recfamation 'ancl Mine(iDrainage Conference and Third International
''Conferen'ce"on tite^ v. 2 of 4, U.sr Bureau of Mines JSpecial
PublicationSP06B-94, pp. "138-147.
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1-93 " ' ' ' "'" Hydrologic Controls
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Coal Remining BMP Guidance Manual
Zipper, C. E., T. Younos, and E. Yagow, Comparative Effects of Alternative Re-mining and
Reclamation Strategies on Erosion Potential at a Case Study Abandoned Mine Land Site, 1992
National Meeting of the American Society for Surface Mining and Reclamation, Duluth, MN. pp.
671-679.
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Coal Remitting BMP Guidance Manual
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Coal Remining BMP Guidance Manual
Section 2.0 Geochemical Best Management Practices
Introduction
The previous section discussed how hydrologic best management practices (BMPs) can reduce
pollution load from remining sites. This section will discuss BMPs that use geochemical approaches
to reduce pollution load. Effective use of geochemical BMPs requires at least a rudimentary
understanding of the acid-producing and acid-neutralizing chemical processes.
Acid mine drainage results from the oxidation of pyrite (FeS2). The following summary equation
shows the reactants and products:
FeS2 + 3.75 O2 + 3.5 H2O - Fe(OH)3(s) + 2 SO42- + 4 H+
(Equation 1)
Pyrite in the presence of oxygen and water will oxidize to form "yellowboy" [Fe(OH)3(s)], sulfate
(SO42') and acidity (H+). Equation 1 is a summary equation. The following reactions are important
intermediate steps:
FeS2 + 3.5 O2 + H2O - Fe2+ + 2 SO42- + 2 ET
Fe2+ + 0.25 02 + H+ - Fe3+ + 0.5 H2O
(Equation 2)
(Equation 3)
A product of Equations 2 and 3 is ferric iron (Fe3+). Ferric iron can oxidize pyrite in the absence of
oxygen:
FeS2 + 14 Fe3+ + 8 H2O -* 15 Fe2+ + 2 SO 2' + 16 H+
(Equation 4)
The oxidation of pyrite by ferric iron can become cyclical and self-feeding (Stumm and Morgan,
1996). Chemical reactions represented by Equations 1 through 4 occur "naturally," but the rate of
Geochemical Controls
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CoalRemining BMP Guidance Manual
= re'a'ciion can"be enhanced by orders of magnitude by the catalytic influence of bacteria, primarily
TJiiobacillus ferrooxidans. The bacteria obtain energy for their metabolism from the above
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Equally important to any of the above acid-producing reactions is the ability of certain minerals to
neutralize acid. This is illustrated by the dissolution of calcite:
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I ,
CaCO3 + H+ - Ca2+ + HCO3-
CaCO + 2 H+ - Ca2+ + CO2 + H2O
( Equation 5)
I
3
(Equation 6)
In Equation 5, acidity (H+) is neutralized and alkalinity (HCO3~) is produced. In Equation 6 acidity
is neutralized,'^but no alkalinity is generated. Whether Equation 5 or 6 dominates depends on how
open or closed the system is to the atmosphere (Guo and Cravotta, 1996). In a more closed system
Equation 3 will dominate.
Two overall reactions can be written to describe pyrite oxidation (acid production) and carbonate
dissolution (acid neutralization) in a closed (Equation 7) and open (Equation 8)_ system:
FeS2 + 4 CaCO3 + 3.75 02 + 3.5 H2O - Fe(OH)3 + 2 SO42- + 4 Ca2+ + 4 HCO3- (Equation?)
FeS2 + 2 CaCO3 + 3.75 O2 + 1.5 H2O - Fe(OH)3 + 2 SO42' + 2 Ca2+ + 2 CO2 (Equation 8)
Chemical BMPs attempt to counter the acid-generating chemical reactions in one or more ways.
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Approaches include the following:
preventing pyrite from being oxidized
ji
keeping water away from pyrite
neutralization of acid by dissolution of calcareous materials
inhibition of the bacterial catalysis.
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The chemical BMPs examined in this section are alkaline addition, induced alkaline recharge, special
handling of acid-forming materials, and bactericides. Alkaline addition can positively affect mine
2-2
Geochemical Controls
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Coal Remining BMP Guidance Manual
drainage in several ways. It can neutralize acid generated from pyrite oxidation, it can elevate pH,
which can have an inhibitory effect on bacteria, and it can facilitate precipitation of ferric iron
(Fe3+), thus reducing its role in pyrite oxidation. Induced alkaline recharge is a hybrid of
geochemical and hydrologic controls. The geochemical aspect is largely neutralization of acid.
Special handling can be used to keep water or oxygen away from pyrite. Bactericides are used
specifically for stopping the influence of bacteria on the acid mine drainage (AMD)-generating
process.
Geochemical Controls
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Coal Remining BMP Guidance Manual
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Geochemical Controls
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Coal Remining BMP Guidance Manual
2.1 Sampling
Introduction
Proper planning for implementation of geochemical BMPs requires an adequate understanding of
overburden characterization and sampling. This discussion on sampling is primarily taken from
Tarantino and Shaffer (1998), and supplemented by data from Sames and others (in preparation).
Sames and others surveyed all Appalachian coal mining states to determine sampling protocol
and interpretative techniques used by the various states.
The results of overburden analyses are generally used in two ways: 1) as a permitting decision-
making tool (determining whether the permit is issuable), and 2) as a management tool (using the
information to design best management practices for avoidance or remediation of pollution).
This section will concentrate on using overburden sampling for providing insights into the design
of best management practices. Representative overburden sampling is used to:"
determine overall acid or alkaline-producing potential of a proposed mine;
calculate alkaline addition rates;
determine the distribution of pyritic zones that may require special handling or avoidance;
identify alkaline zones which can be incorporated into a mining plan to prevent acidic
drainage (i.e., alkaline redistribution); and,
determine the economic feasibility of mining without unacceptable environmental
impacts.
Geochemical Controls
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Ill I III I 111
Coal Remining BMP Guidance Manual
fAcid-Base Accounting
Ill Mill I II i i1 .'!'"' !! iSi.l !, I' I V. , ' "Mi i !!-'l>ป ''I liirf! V.;" j 'jstt j": >;!!'::" ; '''i
Overburden analysis (OB A) refers to determination of the acidity or alkalinity pro
potential of the rocks that will be disturbed by mining. OB A methods fall into two broad
categories: static and kinetic. Static tests are "whole rock analyses" that determine the
concentration of elements or minerals. Kinetic tests are simulated weathering procedures that
attempt to reproduce weathering. In short, static tests measure what is in the rock and kinetic
tests measure what comes out of the rock. By far the most commonly used overburden analysis
method in the Appalachian region is static "acid-base accounting" (ABA).
I ! ;, j||, ,' R,
I I1"1 "i"1! ."illI,, " >!"*
Ml !!'' " , "
Components of ABA
ABA is based on the premise that the propensity for a site to produce acid mine drainage can be
predicted by quantitatively determining the total amount of acidity and alkalinity contained in
samples representative of site overburden. The maximum potential acidity (expressed as a
negative concentration of CaCO3) and total potential alkalinity (termed neutralization potential
ll'i!!!IJ,,ni , " 'i '" !"!,i," i,.! , I'ii,iii!l! IS" , i: I" "'i/i'!,! '., V!1 ' ",',11,,:", i, 'i,!;' , ' ,," ! ,j,|. ,:' !"> i,'"', "ill."'| "" i ,i ,!'','hili!,, ||., d''.'JllHiiiU/U 'it, !! HlU'r , if I i >W ,: i' ,l'ป il" n ' . i |.i '.!' HU ..,' UK?, <. v '<,: 'ti ,,i,iji:a, : i ivs1 imi " JIM, '' ir-'iui,
II i fl iiii ซiiiEiiiiiii, , r; ':' ": , ">i "w:. a ' '! l;>": ' ~-y^ '< ' i .n.ป i" ปป ,.i ^,. -' >. "
produce alkaline water. If it is negative, the site should produce acidic water. The maximum
potential acidity (MPA) is stoichiometricaiiy calculated &bm'tne' percent sulfur (S) in the
overburden. Sobek and others (1978), noting that 3.125 g of CaCO3 is theoretically capable of
I ' " '"
neutralizing the acid produced from 1 g of S (in the form of FeS2 ), suggested that the amount of
potential acidity in 1000 tons of overburden could be calculated by multiplying the percent S
times 31.25. This factor is derived from the stoichiometric relationships in Equation 9 and
carries the assumption that the CO2 exsolves as a gas.
FeS2 + 2 CaCO3 + 3.75 O2 +1.5 H2O -> Fe(OH)3 + 2 SO/-+ 2 Ca2+ + CO2(g) (Equation 9)
's -,i,;i M
: fl' '"iii
2-6
Geochemical Controls
INl HI nllnllil J,| IIIVJIrllH^^^^^^^^^
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Coal Remining BMP Guidance Manual
Cravotta and others, (1990) suggested that, in backfills where CO2 cannot readily exsolve, the
CO2 dissolves and reacts with water to form carbonic acid and that the maximum potential
acidity in 1000 tons of overburden should be derived by multiplying the percent S times 62.50.
In short, however, it can be said that interpretation of ABA data is far more complicated than
simply summing the MPA and neutralization potential (NP) values. In addition to the percent
sulfur and NP determinations, two other measured parameters in an ABA overburden analysis
are paste pH and "fizz."
Paste pH
Paste pH has its origin in soil science, where weathered material (soil) is analyzed. A portion of
prepared sample is mixed with deionized water, and then tested with a pH probe after one hour.
The paste pH test indicates the number of free hydrogen ions in the prepared sample, However,
since pyrite oxidation reactions are time dependent, the paste pH results provide little indication
of the propensity of a sample to produce acid mine drainage. In fact, the paste pH of a
unweathered, high-sulfur sample is likely to be near that of deionized water, while a weathered
sample with relatively low percent sulfur (but which includes a small amount of residual
weathering products) may have a significantly depressed paste pH. Thus, paste pH is of limited
use when dealing with unweathered rock.
Percent Sulfur
Since acid mine drainage results from weathering of sulfide minerals, the amount of sulfur in a
sample, or in an overburden column, is obviously an important component of ABA.
Sulfur determinations for ABA are often performed for total sulfur only, however,
determinations for forms of sulfur are sometimes included. Sulfur generally occurs in one of
three forms in the rock strata associated with coals in Appalachia: sulfide sulfur, organic sulfur,
and sulfate sulfur.
Geochemical Controls
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Illitiivi, I i-,1 i!' v llif :; ." " '1(11 '.ffiM i ,,', ' , v
Coal Remitting BMP Guidance Manual
Sulfide sulfur is that sulfur that reacts with oxygen and water to form acid mine drainage..
The suifide minerals most commonly associated with coal in Appalachia are pyrite arid
marcasite, both of which have the formula FeS2.
Organic sulfur is that sulfur which occurs in carbon-based molecu es in coal and other
rocks with significant carbon content. Since organic sulfur is tied up in compounds that
rflll'Wil , l,,l''''l!'i!,,':":i' !"
!"' 1, ' IHii'WWfll1 I II
are stable under surface conditions, it is generally not considered a contributor to AMD.
Organic sulfur is only a small percentage of total sulfur for most rock typesj but can be
significant in coal.
Sulfate sulfur, in humid climates, is generally found in relatively small concentrations
due to its association with high-solubility minerals. However, when present in
Appalachia, sulfate sulfur often occurs in partially weathered samples as a reaction by-
product of sulfide-mineral oxidation. When solubilized, these by-products are the source
of the contaminants found in acid mine drainage. For that reason, when determinations
for forms of sulfur are performed, sulfate sulfur should be considered in the calculation of
MPA. Alkaline earth sulfate minerals such as gypsum (CaSO4) can also contribute to the
sulfate sulfur fraction, but generally are not abundant in coal-bearing rocks in Appalachia.
Where they are present, the alkaline earth-sulfate minerals do not contribute to acidity
- i "t!""'!" '* ''f If' "'"|: ":;':|"raricf snould'no'ife.cou^ed'in'tiiie calculation^
1998).
Ill I III I I I ' r " v, : i || '
11 ll
LiiFI' "!* "'
I M, ป.;':'
A review of the methods for sulfur determinations described in Noll and others, (1988) reveals
that the methods for total sulfur determinations have a relatively high degree of precision with
few notable interferences and precautions, while methods for determination of the forms of sulfur
had lesser degrees of precision and more numerous potential interferences. Stanton and Renton
(1981) examined the nitric acid dissolution procedure, which is the cornerstone of the most
iii,:, ,f;: t:: i; ? ^ 4 ซ, 111 ซ:':>.;, *; 3M' .siiji}: .s'ซ :... i [.;..; I'V ILM ] %,,, ~: ^ ?,- ' . j;v, i', i ;:*: "Sa 4. r mwi. i" Jf**! :"41, t ,';, ; .lit1 fi . *: t T 7. tซi tins: J"1:
frequently used methods for determining pyritic sulfur, including American Society for Testing
and Materials (ASTM) D2492. They found the procedure frequently does not succeed in
2-8
Geochemical Controls
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CoalRemining BMP Guidance Ma
digesting all the pyrite, and thus underestimates the pyritic fraction of the sulfur. Brady and
others (1990) compared total sulfur and forms of sulfur determinations performed by various
laboratories. Their findings include:
While the results generated by each laboratory were internally consistent in terms of the
ratio of pyritic sulfur to total sulfur, there were significant differences between
laboratories in the median percent pyritic sulfur/total sulfur. Where the same samples
were analyzed by different laboratories, differences were noted in the pyritic
determinations, but total sulfur determinations were comparable.
There was no significant difference in the percent pyritic sulfur/total sulfur between rock
types (excluding coal). This contradicts one of the primary reasons for determining forms
of sulfur: that some rock types contain significant percentages of organic sulfur.
With one exception, all laboratories used high temperature combustion for determining
weight percent total sulfur. The high temperature combustion results compared well on
duplicate samples, while the pyritic results on the same samples did not.
Standards are available from the National Institute of Standards and Technology for total
sulfur but not for pyritic sulfur.
A wide range of methods for determining pyritic sulfur were in use and individual
laboratories had their own variations of the methods.
According to ASTM Committee D-5 on Coal and Coke, the most commonly used method
of pyritic sulfur determination, ASTM D2492, was developed for use on coal and:
probably not appropriate for determinations on rock overburden.
.is
Geochemical Controls
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- :: !>:"ป at:;
i<? :ปf
Coal Remining BMP Guidance Manual
The above findings can be summarized as:
'-'IS '!!;;*'ilfflliill I
Total sulfur determinations are typically simple to perform, are reproducible, and can be
:"':'" ::::::: '::: : ' : '':" :: -. ' ...." :.. '. , i :' '. : .'. : "- ,;:::::'
calibrated and verified using available standards;
:. ij" 'I11 ฃ Jlllllll '"
pyritic sulfur is determined using a variety of methods (the most common of which is
considered inappropriate for rock samples),
"SI T^
."li1'1'1,!!!' I i'" '
ritic sulfur methods produce results which are often not reproducible between
laboratories, and cannot be calibrated and verified using available standards.
'f ' I 'fill!!:1' !.,ป!
'" l|ilj| : 'll' !!'"''''"!!,!' 'i'''"1""1" l ''l!?Bl'!i '! '''' '':< ''? /i*'!1!'1:!111" ' ! ' , ''' ''Jlils!
Oiveri these considerations, and that pyritic sulfur is the most abundant form in coal overburden
(but not necessarily in the coal), total sulfur determinations currently provide the best basis for
calculating
Fizz Rating
The fizz test is a subjective test measured visually and rated as to the amount of effervescence
when one to two drops of 25 percent HC1 is added to a small amount of finely-ground sample
(Sobek and others, 1978). Fizz .ratings range from strong effervescence to none. The fizz test
Klin; In i 'i : ' i 'iii11' lliiiillin mil '"'i,1 , f ',i ' ,!> . . ,, ' ''-, J'v IS II," ' 'J .1,1, If < i/ I . ii'U.il.i'1 I :
in1 ;| ,;.(,;<. JMC. i: p11"1 ' v .!,:, , . ,. - . i
Serves two functions:
as a check on the NP determination,, since there should be a qualitative correlation
between the two. Calcareous rocks with high NP should show a strong fizz, whereas
ndn-caicareous rocks should not; arid
more importantly, the fizz rating determines the volume and the strength of the acid that
.'""i1,; i'^'11;;;; ;;'":';;;;,;, ; ', ; ,,:,,"' ;, ,: r ,::,, "" ;,, .' ฐ ,;"".' , , ,' ' :, "' ;;;;;' "'..," ,' "",, '.,.:,..';,: . ',: ; "! ,.."':,,,:", ; :".";, : , .;;;;;;;,:: ' ,' :; ;;,";';,
I
is used to digest samples for NP determinations.
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Geochemical Controls
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Coal Remining BMP Guidance Manual
Neutralization Potential
The first step of the NP test is to conduct a qualitative fizz test on a small amount of the prepared
sample as described above. Based on the fizz test results, an appropriate volume and normality
of HC1 is selected then added to 2.0 grams of prepared sample (Noll and others, 1988; Sobek and
others, 1978). The strength of the acid is chosen to assure complete digestion of acid-
neutralizing minerals. The neutralization potential is calculated by determining the amount of
acid that has been neutralized by the rock.
Carbonate minerals, such as calcite and dolomite, are known to be major contributors to ground-
water alkalinity in the coal regions of the Appalachians. The acid-digestion step of the NP test is
suspected of dissolving various silicate minerals, which results in aNP determination that
overstates the amount of carbonate minerals in a sample. Lapakko (1993) noted that since this
dissolution will only take place at low pH values, it is unlikely to help maintain a drainage pH of
acceptable quality.
Siderite (FeCO3) is common in Appalachian coal overburdens, and has long been suspected of
interfering with the accuracy of NP determinations and of complicating the interpretation of the
data (Skousen and others, 1997). If iron from siderite is not completely oxidized when the
titration is terminated, the calculated NP value will be overstated. Skousen and others (1997)
found that the addition of hydrogen peroxide (H2O2) following sample digestion can expedite
oxidation, and precipitation of iron. Samples exposed to H,O2 digestion produced results similar
to those of samples containing little pyrite or siderite. The additional H2O2 digestion step
provided the lowest NP values for samples with significant siderite content and the best
reproducibility between laboratories.
Net Neutralization Potential
Neutralization potential and maximum potential acidity are both expressed in units of tons
CaCO3 equivalent per 1000 tons of material (e.g., parts per thousand CaCO3). Net neutralization
Geochemical Controls
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Coal Remining BMP Guidance Manual
r,1 if a ;ป>?wiir.iiji/'
potential (NNP) is neutralization potential minus maximum potential acidity. Thus, if the NNP
is positive, there is an excess of neutralizes. If the NNP is negative there is a deficiency of
III III II 111 III 111
Studies comparing ABA with post-mining water quality have consistently shown that although
NP and MPA have the same units of tons CaCO3 per thousand tons of material, and in theory
should be "equal," their relative importance is not equal. It takes an excess of NP to assure that
post-mining water will be alkaline (diPretoro, 1986; Erickson and Hedin, 1988; Brady and
others, 1994; Perry, 1998). Post-mining water quality predictions should riot be based on ABA
alone, but should employ an array of prediction techniques, the best decisions involve
consideration of as much data as is available (Kania, 1998b).
Information Needed to Conduct an Overburden Analysis
The site-specific data needed to properly plan an overburden analysis (OBA) includes:
Mining limits: -boundaries of the proposed area to be affected by coal removal;
':'',:T, !!'! IMIIHii, ฐ |. , ;,.,,.- r, i . , I
-proposed maximum highwall heights;
-type of mining (e.g., contour/block cut or hill top removal); and
-accessibility to drilling locations
Geologic considerations such as coal-seam identification^ depth of" weathering, arid
stratigraphic variation.
' ' ' '" ' ' |l
^formation available in state mining office permit files, such as water quality data from
previous permits or applications covering the same or adjacent areas.
Overburden analyses from the same or adjacent areas.
Publications of state geologic surveys, the US Geologic Survey (USGS), the former US
Bureau of Mines (USBM), US Army Corps of Engineers, and miscellaneous other state
specific publications (e.g. the Pennsylvania "Operation Scarlift" reports from the late
ill I III III in ;, ',,!" "v"' 1. f" .i|"i i ,,: i11' I I | I ' i,1''1;/!1 '.I". ,' . i'!:i!i ii'""!
1960s arid early 1970s). These publications can include information such as:
2-12
IliKB :'
Geochemical Controls
i in 11 iii in
ifeiliM^^^ liiiiliiii iililiJliป liiiiii it I
-------
Coal Remining BMP Guidance Manual
-coal-bed outcrop maps,
-generalized stratigraphic sections,
-coal seam thickness maps,
-structure contour maps.
Old and current deep mine maps are available from the Office of Surface Mining, Appalachian
Region Coordination Center, at 3 Parkway Center, Pittsburgh, PA, 15220, and various state
agencies. These agencies have map repositories containing prints, originals, and microfilm, and
copies can be readily obtained. These repositories include the Works Progress Administration
(WPA) deep mine maps prepared in the 1930s, which cover an area that is 1/9 of a 15 minute
quadrangle. In addition to showing mining limits, deep mine maps frequently show structure
contours. This information can be very helpful in planning OBA drilling.
Other considerations in developing an OBA drilling plan include:
Exploration equipment. It is important to understand the limitations that are inherent
with different types of drilling equipment. These limitations can have an impact on the
ability to obtain unbiased, representative samples. The choice of exploration equipment
can influence costs.
The type of overburden analysis to be performed. This is important in determining how
much sample and what size fraction is required for the specific type of testing to be
employed.
Time constraints. Air rotary drilling is normally faster than coring.
Economic constraints. Air rotary drilling is generally less expensive than coring.
Geochemical Controls
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;::::; Coa/ Remitting BMP Guidance Manual
ป'! i, ? {"11111"', in .;
Preparing for Overburden Analysis Sampling
ป:i " , illlft. LIU i =',-'!. ' i . , ii'M" )': , i ',' ' ill ;' t
The obvious questions that need to be asked when planning an OB A drilling plan are:
How many OB A holes are needed ?
Where should the drill holes be located ?
Once these details have been worked out, preliminary work can start.
The first step in the development of an OBA proposal is to plan for the drilling. While there may
appear to be savings associated with performing the drilling for the overburden analysis as part
of the initial exploration drilling, it is generally preferable to perform exploratory drilling
throughout the entire site before OBA drilling is initiated. This preliminary drilling enables the
determination of depth to coal and the lateral extent of strata. This information can then be used
to locate overburden holes best suited to represent the lithologic variation and degree of
weathering within the site. If research and exploration are doneprior to drilling the OBA holes,
it is less likely that there will be a need to drill additional OBA holes later during the permitting
process.
"i '!? i I,
Areal Sampting-A Survey of State Practices
;"'' ;, ;,; , , ,; ;, ;; i i - "";,, ;; , ",,i;"ii!: ' ," ,j:: , / :" ' "'"!"; ,:'.
\
Sames and others (in preparation) surveyed Appalachian coal states to determine rules-of-thumb
i='jFor area! sample coverage. According to Sames and others (in preparation) "all the states
r'intenn[ewa3,'exceglrv'irginia, h'ave some minimum sp^atial'distribution requirements for
overburden analysis that should be supplemented upon request from the reviewing
profession Table 2.la shows the minimum drill hole spacing requirements by state.
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Geochemical Controls
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Coal Remining BMP Guidance Manual
Table 2. la: Minimum Overburden Analysis Drill Hole Spacing Requirements by State
(Sames and others, in preparation)
State
Minimum Requirement
Comments
AL
Two drill holes on small permit properties (<10 acres).
One drill hole per 160 acres, or one per property quarter
on larger permits.
KY
Eastern KY: Drill holes should be distributed on a
staggered, one-quarter mile grid pattern.
Western KY: Drill holes should be distributed on a
staggered, one-half mile grid pattern.
MD
One drill hole per site regardless of size
PA
Two drill holes per site regardless of size. However, a
rule-of-thumb of 2 drill holes per site plus 1 drill hole
per 100 acres is usually requested.
On average, most applications
contain 1 overburden analysis hole
for every 20 permit acres.
TN
One drill hole per 60 to 100 acres for permits to mine
coal beds considered a high risk for AMD, based on
past experience. One sample point per one-quarter mile
in coal beds considered a low risk for AMD.
VA
In general, accepts any
information submitted by the
applicant, considers the quantity,
quality, and consistency of the
OBA for the permit area, and
decides whether a reasonable
characterization of the site is
possible based on the spatial
distribution provided.
WV
One drill hole in low cover and one in high cover.
Otherwise, regulatory agency geologists to utilize Best
Professional Judgement when determining the number
of drill holes required for a permit.
In general, accepts any
information submitted by the
applicant, considers the quantity,
quality, and consistency of the
OBA for the permit area, and
decides whether a reasonable
characterization of the site is
possible based on the spatial
distribution provided.
Geochemical Controls
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Coal Remining BMP Guidance Manual
I; in!, Itii'l ' ""'it
iitii: i'l it.!,'"1:,1;::1::
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Areal Sampling Experience: Pennsylvania
Pennsylvania has grappled with the issue of drill hole distribution since the advent of overburden
sampling. A rule of thumb developed in Pennsylvania in the 1980s to determine a suggested
minimum number of overburden holes was:
Number of acres to be mined + 2 = Number of
100 Acres Overburden Holes
'I'rtii1'! ;, V9R
ป;l|: , ill in,i
ff the first part of the equation resulted in a fraction, it was rounded to the closest whole number.
illiii'H ' J nill' , ift. ,l!i|'i5iiilllil|iili ,,, In I , : ' ',li * FII ', , , ,'i :' /i. wii' I'flttn '., i, 'w.iiit \mf*: .r'i< ซ .1 M
greater than the arule of thumb." A recent survey of overburden hole coverage for 38 sites in
Pennsylvania revealed that on average, there is one OB A hole for every 15.5 acres of coal.
inn n i inn in in i, |. " ', ,, 111''ป 'i'"1!11 i" "i MI, .iw:1""!,,11 ,'i i1 i1" ,; n i .,!"" , 'nmn; iii ', ' i,11,1!, , I ini;n'' ปi , . .i1!1"!,! i." .^ i
removal (Table 2. Ib).
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Geochemical Controls
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Coal Remining BMP Guidance Manual
Table 2.1b: Number of Acres per Overburden Analysis Hole (Brady and others, 1994)
n = 38
Mean
Median
Minimum
Maximum
Std. Deviation
Coal Acreage
43.5
30.3
5.0
172.5
38.0
Acres per OBA Hole
15.5
11.9
2.3
44.9
10.6
A similar survey of 31 Small Operator Assistance Program (SOAP) applications received in
Pennsylvania during the 1993 calendar year revealed that on average, there was one hole for each
18.8 acres of coal removal (Table 2.1c).
Table 2.1c: Number of Acres per Overburden Analysis Hole Based on SOAP
Applications Received in 1993 (Tarantino and Shaffer, 1998)
n = 31
Average
Median
Minimum
Maximum
Std. Deviation
Coal Acres
72.6
55.0
6.0
220.0
54.6
Acres per OBA Hole
18.8
15.7
3.0
53.5
12.3
The above tables give an idea of the range of overburden analysis sampling intensity used in
Pennsylvania. The ranges in the data are due to a multitude of factors including stratigraphic
complexity of the site, shape of the site, and availability of other prediction tools. Approximately
30 to 40 percent of applications in Pennsylvania do not require submittal of overburden analysis
because of the availability of equivalent prediction data. The data included in these tables apply
only to permit applications that included overburden analysis data.
Geochemical Controls
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Coal RpmiqiQg, BMP Guidance Manual
Operational Considerations
11!"!!'- I'1'"-!,, .J'Lii*
'I""!'!!1!, '( .'In!'" ... !'")!'
The overburden analysis drilling program should accurately represent the overburden that will be
encountered during mining operations. Therefore, the overburden holes should be located within
the limits of the proposed mining area. Some holes should be located at maximum highwall
conditions (maximum overburden cover to be mined), and the holes should represent all of the
strata that will be encountered. Additional holes should be located under both low and average
cover conditions to provide representative sampling of the overburden where stratigraphic units
may be missing or the strata may have been chemically altered due to surface weathering.
^Stratigraphic Variation
r<*\ป :;'ป '',i,iii.ii!r!!iii. rwir jiii! '. ,.
li 'iS i;1!!1, i I i:1!,!, '.>,''VUM1' rfiil'F mi i.1'" ill.1.
.am"i" ป;i., if.. .Jin .".Hi .".Hill! f.u...j i. 'I1',si
M '
It is important to provide enough drill holes to adequately represent the site, including any spatial
litholbgic variaSbri. One of the first references to the minimum overburden hole spacing is
;-i; '; ' ' fcbntajned^ ...... |urf;ace Mine Drainage Task Force's "Suggested Guidelines for
',W*' ..... ' ! i : liSiirface Mining in Potentially Acid-Producing Areas" (1978), which recommended that all
'Fii ,i. ..... : rงj^apepgi|mM''inpoteniti'ally acid-producing areas be witWn apprbximately 3300 feet of a
:11 ' ..... 1 1 ' ftl ri'.ii4W:\Jf ป.: II I.'1.!"'' ';.!*.ซซป ....... *'><:* ........ .;ซ?,ซ l,'!? ...... , . & , ,;ซ,, ...... 5l.iti
sampled overburden analysis hole or highwall.
Dpnaldson and Renton (1984) and Donaldson and Eble (1991) indicated that although drill cores
spaced up to two miles apart in the Pittsburgh coal seam were adequate to reflect major thickness
and sulfur trends for the coal seam, this spacing was not adequate for mine operation design.
They felt that sampling at intervals on the order of 1200 to 1400 feet for the Pittsburgh coal and
Campling at intervals of less than 500 feet for the Waynesburg coal would be necessary to
111 III l" I 111 111111111 I I -. ',., .lli,1!, J. .I".,'.' ! . iMII'liiliiiJi.'!!1;.. tailr. ',,i Kit ;- J, '.li.1';, j ; J'. !'!!i!'l: ffl f ' .I!.! Bits: '. ,f," "
determine small-scale sulfur content trends within the coal seams.
:..i.ll": illrt IK Kill. .
^Representative Samples
..rHilli; , . nil: i", .'I. ..it",, l M,
Each OB A borehole contains sample intervals representing various unit thicknesses of each
ir1 '!" illi|i, ;l!lj '" :'"' .."." I \- 'I .' 1''':' ;i! ,'." '\''"i /'*!; '-I.ปi,', *,:'" t }/ฃ.;: .III' itl:!,:1 If I'! '$('.'"ซ< t,: il'i"1'.':.; .""'" ;! K';':;'. ' i :" '! I!'1'i:' * I .I!
thologic unit encountered. Vertical sample interval thicknesses are typically three feet. The
",;:' ..i-'sii1.. iKXi i. ,;,',., '';>: i';,-!'1':"'" :""; ; ;":"i!: ."l:: laiiJi:.>
I"!!,'. I1!
ft I
KM I.",1 11-1! Hi ... i".;ll i!!. 'ซi:t.' i1:;! I lปf'il.T' I!'*,. I" .
':.]..;,!"i! i;,. ..;(! j1:: I-::;,"!! is .: (,>ซ.;*,
' if! i!l II fllih'l .il,!.."!,
!11 I '',i "".Jllfj, 'Sr1;1
2-18
Geochemical Controls
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Coal Remining BMP Guidance Manual
maximum thickness of each lithologic unit to be represented by one vertical sample interval will
be discussed under "Compositing and Laboratory Preparation." It is also discussed on pages 29 to
30 of Part 1 "Collection and Preparation of Sample" in the "Overburden Sampling and Testing
Manual" (Noll and others, 1988).
Noll and others (1988) do not, however, discuss the complexity of ensuring that accurate, non-
biased, representative samples are collected. They do stress that it is critical that 100 percent of
the sample volume of each sample interval be included for compositing purposes, because of
possible geochemical variations within the 3-foot interval. The ultimate sample size used in
ABA is 1 gram for total percent sulfur and 2 grams for the neutralization potential (NP) test.
Assuming no loss or contamination of the zone being sampled, only 1 gram to 2 grams are tested
out of a 25,550 gram sample (based upon a 4.5 inch diameter drill bit and using an average rock
density of 170 lbs/ft3). Fortunately, sample preparation procedures have been developed to
obtain representative, small sample aliquots. These procedures are discussed below in
"Preparation of Samples."
Extensive literature has been published, and a complete science has been developed to integrate
geology and statistics for spatial sampling and the determination of optimal sampling patterns for
estimating the mean value of spatially distributed geologic variables. Textbooks on the subject
include Journel and Huijbregts (1981), Webster and Burgress (1984), J.C. Davis (1986) and
Koch and Link (1970).
Fortunately, the geologic systems responsible for the deposition and alteration of sediments and
their chemical quality do not operate in a completely random fashion at the cubic centimeter
level and, thus, do not produce overburden samples that are statistically independent. Although
there are exceptions, most stratigraphic systems, especially those which produce calcareous
material, operate over large areas with some degree of order, and deposit laterally pervasive units
(Caruccio and others, 1980). Lateral continuity has also been observed in high-sulfur strata.
Abrupt lateral changes in stratigraphy can occur such as where channel sandstones cut out and
replace other strata. Surface weathering also causes changes to the percent total sulfur and NP
Geochemical Controls
2-19
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Coal Rtmining BMP Guidance Manual
:*:, -
'liii[4 ill
'.W' !"if 'fin*
over short distances. Therefore, it is imperative to know the areal extent of any alkaline or acidic
material, and adequate exploratory drilling is essential for a representative overburden sampling
plan.
Sample collection and handling
'. niii
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jlSampte Collection
ilLi ! ' ,' !.ifl'',;f|ปป i'ill ,vt(',, " ", . 'i! 'i, , ' ' ," " i. ,' , ! ,",:',' :"< I1*;:' ." i!", ",, ' ! ii , I'l1':".' '- f,,.
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Overburden sampling is accomplished by drilling or direct collection of the sample from an open
surface such as a highwall. Sample methods used to obtain overburden samples include air
rotary (normal circulation), air rotary (reverse circulation), diamond core, augering, and highwall
sampling.
' illMr'i,
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Air rotary (normal circulation) - This type of drill is the method most commonly used for the
collection of pvgrburden samples in Pennsylvania. Drilling in this manner uses air to blow rock
chips (cuttings) to the surface for collection. The most common disadvantage of normal
circulation air rotary drilling is that individual samples of stratum can be contaminated by an
overlying sample zone as the rock chips are blown up the annular space of the drill hole. Rock
chips traveling in this space can dislodge loose particles from an overlying source. Care should
foe!งfeen to stop the downward progression of the drill stem after each interval has been sampled
iilBr 'i'l'llilli;:!!"! Ill 111 111 II I III Illlll I I I III
and allow any upper loose particles to blow out prior to continuing downward.
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f;!i :>' *.< ill! i'i III 'I 11
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Contamination of the sample can also occur at the surface from the pile of ejected material that
forms near the drill hole. These piled materials, if not removed during drilling, can slough back
tpr,i,i!ป, inliir.;.. i. , ^ . i
iptp tlie open hole and the chip stream. This can be avoided by shoveling the materials away
from the hole during the period when drilling is stopped to blow out the hole. Another option is
to add a short length of casing to the top of the hole after the upper few feet or first sample
interval has been collected.
:ปi. .!',' : "IIU D Ill
II
rl-20
Geochemical Controls
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-------
Coal Remining BMP Guidance Manual
Samples are collected by placing a shovel under the chip stream. Care should be taken to clean
the shovel of any accumulated materials from previous usage or sampling. This is particularly
important when sampling wet test holes where the ejected materials consist primarily of mud.
Before drilling the overburden hole, the dust collector hood should be cleaned to remove any
accumulated materials that may dislodge and contaminate the samples being collected.
Air rotary (reverse circulation) - This type of drill rig is less commonly used for the collection of
\
overburden samples, primarily because of availability. A reverse circulation rig uses a double-
walled drill stem. Water or air is forced down the outer section of the drill stem and the
cuttings/chips are forced up the inner section of the drill stem. The cuttings and water or air are
brought into a separator and dropped near the rig where the samples can be collected. The
samples are isolated from contact with overlying strata, offering a much cleaner and quicker
means of obtaining overburden samples, without requiring that the drilling be stopped to blow
out the hole. If water is employed in the drilling process, the materials are also washed free of
the fine dust coating that can accumulate on the chips during drilling with air. This allows for
much easier rock type identification and logging.
Diamond core - Diamond core barrels can be used on both types of rotary drilling platforms.
Coring provides a continuous record of the lithology and provides more information than can be
obtained through the collection of rock chips. Cores can provide a better overall view of the
lithology by providing information necessary to judge rock color, gross mineralogy, grain
size/texture, fossil content, and relative hardness. This type of information is not always readily
available from rock chips. Although a core provides an uncontaminated and better source of
reliable lithologic data, coring is very time consuming and costly, especially if the entire
overburden section is to be sampled. Diamond cores can be used as a secondary means of data
collection to target previously identified problem zones, or as a primary sampling tool in the coal
area (i.e. the interval 5 feet above and below the coal horizon). The entire sample interval from
the core should be collected and processed for analysis to ensure representative sampling, as
opposed to only collecting and analyzing a portion of the sample interval.
Geochemical Controls
2-21
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Coal Remitting BMP Guidance Manual
\ III1 1 |||II| |l 111 111 III i Hill III i I I i nil III I II II I 'i'>-4:;iซ:;;l'f:'!|i: I
A problem that can occur with coring is "core loss." The problems of core loss can be reduced by
regulating the drilling speed, (i.e., rotational speed of the bit, and down pressure), diameter and
"type of core bit, and amount of water; by minimizing the overbearing weight in the core barrel
through emptying it prior to drilling the coal, and by keeping the equipment in good condition.
Knowing what drilling adjustments to make can prevent blocking of the core barrel.
;'
5'; Successful coring is dependent primarily upon the experience of the pn-site geologist, project
engineer, or driller. Factors that are important include total years of core drilling experience,
i
experience with the drill being used, and previous drilling experience in the same region,
including exposure to the same rock formations and weathering characteristics. Having as much
?: [' " " ' ::'; ' "''i ?:":',, :'" :, : ;ฃ; ,' '; '*"' IM1, *''r I;:,,;'": i:;; :!;;!"l:::,, :J
geologic data as possible (e.g. approximate depth to the coal, extent of weathering) prior to
drilling is also particularly useful. It is especially useful to have air rotary pilot holes to evaluate
the site prior to the core drilling. These pilot holes allow particularly troublesome formations to
f'!,'! ,,;,n .I'l'ii1* ;*il'l!!!l,!!K; .lliillP i K; < : ,'lllt;
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Coal Remining BMP Guidance Manual
In addition to actual core sample loss, drilling data can be lost due to improper handling of the
cores. Data loss causes include placing cores in the core boxes in the wrong order or upside
down, or damage caused to the core during handling and shipping.
Augering - Auger drilling is not recommended for general overburden sampling. The materials
lifted by the auger screw are in constant contact with the overlying stratum, thus providing for
intermixing and contamination. Augering is typically used for unconsolidated or highly
weathered sections.
Highwall sampling - Direct collection of samples from an open source, such as a highwall, can
be used for overburden analysis, provided several caveats are understood. First, samples may be
weathered to such a degree that the strata to be mined is not accurately represented. Second,
there is limited availability and accessibility of highwalls. Care should be taken to collect only
unweathered samples in close proximity to and representative of the proposed mining. It is
recommended that open source (e.g. outcrop, highwall, etc.) samples be used primarily to
supplement drilled overburden samples.
Sample Description (Log)
For each sample or composite of sample intervals collected, an accurate description of the gross
lithology should be determined. This lithologic description should include the rock type (e.g.
shale, sandstone, etc.), rock color (as determined by comparison with the Munsell Rock Color
Chart), texture/grain size, moisture conditions, and relative degree of weathering. Where
applicable, a description of the gross mineralogy should be included with particular emphasis on
the presence of any calcite (CaCO3), siderite (FeCO3), or pyrite (FeS2). In addition, fossils should
be noted to provide insights into coal seam correlations and depositional environment
interpretations. The sample description should include the relative degree of fizz (effervescence)
when doused with a 10 percent solution of hydrochloric acid (HC1). A field fizz based on a scale
of " none, slight, moderate, or strong" should be used. A dilute (10 percent) HC1 solution is
widely used by field geologists to differentiate calcium carbonate (CaCO3) from other carbonate
Geochemical Controls 9 23
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'ซ ',: , , " F 'i
Coat Remining BMP Guidance Manual
rocks. Fizz determinations are highly subjective and should be made by the same individual for
i
every sample on every hole for a particular site. Extreme care should be exercised to be sure that
the displacement of trapped air is not mistaken for CO2 evolution. It is also important to identify
whether the fizz is from the matrix or from the cementing material. It is recommended that
91 . ,,'!':; ' -Mi '' ^/Siiillilliii1'1 Pay .i1 ' in,1' i,i ,"', !:'.' ^ . , "! ,"1'1",,1 '.',., . [ 'Vl'y: ' " , ,i , .I"1 i "'*: ill " ', n >'.;:., |>,l ...iMsr >,'t '/.ifiaHi! ,' i t
logging of test holes, including sample descriptions, be performed by a qualified geologist
T'ปV.'1!!,: i, ill! Ililbiil',1'
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Sample Preparation and Compositing
il! ,,1,11111
ป ' ' ' ป ' " ' " in :,,i.i, - ', ,r ' , 'I folI and others (1988), and
Sobek and others (1978). Procedures discussed in these publications include the use of proper
c.ontainers, labeling, preservation, and field logs. Field sample preparation will not be discussed
further in this section.
"! I":",""''HI,liWI'l 1*11
Sample compositing and laboratory preparation techniques are just as important to the integrity
of a sample. The purpose of compositing overburden samples is to reduce the cost of overburden
analysis by minimizing the volume and number of samples to be tested, without sacrificing the
accuracy and precision needed to predict post-mining water quality. Sobek and others (1978), in
II | I i || 'I III IIP ; |':,' ' i ""I lUII.,, ' , ' '" ' ""I mi, II '. ' It ,',:; '.!,;. ป I I ' 'illivll'V ' ป ,,j|ijil|lli|i ',,, I' iป Hid'';,:'! ป'ป ',!! . ' '". '<$ ,ป',' ' ' ill ' ''I'D !|ป'"! IIL'U.lliillllll^
the first generally accepted "manual" on overburden sampling, recommend that most rock types
should not be combined into composites representing more than 3 feet. They suggest that
sandstone can be composited into 5-ft increments! Experience in some regions, such as
,1
Pennsylvania, has indicated that it is often prudent to sample sandstone at the same resolution as
.other rock types (Tarantino and Shaffer, 1998). As with any well-intended cost-saving procedure,
fpptcione properly,"'the real long-term costs might far outweigh the small cost saving.
!'
pTableg2.!'l1Oi!StsIyerticai sannpling practices of Appalachian cbal-prbducing states.
2-24
11
Geochemical Controls
i 11 in
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Coal Remining BMP Guidance Manual
Table 2.1d: Overburden Interval Sampling Requirements (Sames and others, in
preparation).
STATE
INTERVAL SAMPLING REQUIREMENTS
AL
KY
MD
One sample every 5 feet or at a significant lithologic change, whichever
comes first. Sample compositing is not allowed. Regulatory agency reserves
the right to request core drilling in permit areas where there are known acid-
forming lithologic units.
Same treatment required for samples from eastern and western region.
One sample for suspected acid-producing strata and coal seams less than one
foot thick; smaller strata and seams may be grouped with the next lower unit.
One sample within the lithologic unit for strata one to five feet thick.
Two samples for strata ranging from five to ten feet thick.
One sample every 5 feet for strata more than ten feet thick.
For rotary drill cuttings, one sample every 1 foot or at a significant lithologic
change; for core samples, 3 foot composite samples or at a significant
lithologic change.
PA
TN
VA
One sample per 3 vertical feet or at a lithologic change plus 1 foot above and
below the coal bed. Rotary drill samples should be collected in 1-foot
increments that then can be composited up to 3 feet. Core sample composites
also limited to 3-foot increments regardless of the unit thickness; an equal
portion of the entire core length must also be crushed and split for analysis.
One sample every 3 feet or at a significant lithologic change, whichever
comes first.
Sobek and others (1978) protocol:
One sample every 5 feet for sandstone units.
One sample every 3 feet for other lithologies.
WV
One sample every 5 feet or at a significant lithologic change, whichever
comes first. Sample compositing is not allowed.
Sobek and others (1978) followed as the official guide. Permit geologists also
refer to NPDES, DMR discharge data, and other historical data from adjacent
operations in the same seam.
Some sandstones, such as portions with'significant coal inclusions, may need to be sampled at a
greater resolution. Till, when from separate glaciations, should be sampled separately. The
reason for the 1-foot sample intervals above and below the coal (Pennsylvania) is that these are
Geochemical Controls
2-25
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,WI. '! I Iki:
Coal Remining BMP Guidance Manual
frequently the highest sulfur strata present. Mixing of these strata with overlying strata can result
in dilution ancf a falsely low-percent sulfur, or make a fgicker zone (e.g'V 3 feet) resemble a high
sulfur zone. The coal seam may also require greater sample resolution than the suggested 3-feet
if a portion of the coal will be left in the pit as pit cleanings or unmarketable coal. The coal that
I I II III 11 III III I I II I II I II III II III II I I II I I ' II II J .ป'!'. VllilV Vfirj'r'll'l
remains behind should be sampled separately.
As can be seen from Table 2.1e, if too many 1 foot intervals are composited or too large a
vertical sampling interval is chosen, a high total sulfur, potentially acid-producing zone can be
masked by dilution with adjacent low sulfur strata. The net effect is an underestimation of the
potential for a site to produce acid mine drainage. Compositing one foot of 2.34 percent sulfur
black shale with an overlying four feet of low-sulfur sandstone results in a 0.48 percent total
sulfur for the composited five-foot zone. If, for example, 0.5 percent sulfur is the "threshold"
above which a unit is considered acid producing and thus targeted for special handling; this
dilution effect would underestimate the acid-producing potential of the black shale and result in
the strata not being specially handled.
IB!i/;!;;,,"}ill,; - iir ซwp.ฃ - , ^,v-i m- , /. <... .-ป:
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Table 2.1e: Compositing of Too Many 1-foot Intervals Can Underestimate Acid
Producing Potential (Tarantino and Schafer, 1998)
Thickness
(feet)
1
1
1
1
1
Lithology
sandstone
sandstone
sandstone
sandstone
black shale
Total % S
0.01
0.01
0.01
0.01
2.34
Average % S of Interval
1.18
0.79
0.59
0.48
2-26
Geochemical Controls
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-------
Coal Remining BMP Guidance Manual
Sobek and others (1978) suggested that for core samples, a 5-inch section of the core could be
extracted from the middle of a 1 foot interval to represent the entire one-foot interval. The best
way to ensure representativeness of an interval is to sample the entire interval. In order to avoid
bias, one of the following two methods is recommended:
1) The entire core interval whether it be a 1, 2, or 3 foot interval, should be entirely crushed
and reduced in size via a riffle or rotating sectorial splitter until a suitable amount of
sample remains for analysis.
2) The entire core length should be bisected longitudinally using a core-splitter or saw. One
half of the core is retained for historical records and possible additional testing. The
entire other half of the core is crushed for the entire sampling interval. After crushing,
the sample is divided and reduced in volume via a riffle or rotating sectorial splitter.
There are three reasons for splitting and crushing samples:
1)
2)
3)
To reduce the bulk (amount) of a geological sample.
To provide an unbiased, statistically representative sample of small quantity, which can
be analyzed to evaluate percent sulfur and NP for acid base accounting.
To reduce samples to a small size fraction that maximizes surface area and minimizes the
analytical time.
Geochemical Controls
2-27
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Coal Rfmining BMP Guidance Manual
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Coal Remining BMP Guidance Manual
2.2 Alkaline Addition
It is widely recognized that mine sites with an abundance of naturally-occurring limestone or
alkaline strata produce alkaline water, even in the presence of high sulfur. However, many sites
contain little or no alkaline material and, as a consequence, often produce acidic drainage even
when sulfur contents are relatively low. One approach to improving alkaline deficient sites is to
import alkaline material to amend the spoil in order to obtain alkaline drainage.
Before implementing an alkaline addition BMP, the following factors should be considered:
How much material should be added and how and where should it be applied to the backfill?
When is additional alkaline material needed? What are the prospects of obtaining alkaline
drainage for a given application rate and how much risk of acidic drainage is acceptable?
Ultimately, whether or not alkaline addition is a feasible alternative is driven by the economics of
the operation. Therefore, it is important that an alkaline addition project be carefully evaluated
and designed before it is implemented. This section reviews theoretical and practical aspects of
alkaline addition and summarizes the current state-of-the-art in the use of alkaline addition to
prevent acid mine drainage.
Theory
AMD is formed when pyrite and other iron disulfide minerals present in coal and overburden are
exposed to oxygen and water by mining. The oxidation of pyrite releases dissolved iron,
hydrogen ions (acidity), and sulfate (Equation 1). Although this process occurs very slowly in
undisturbed natural conditions, it can be greatly accelerated by both surface and underground
mining.
Pyrite oxidation is further accelerated by the iron-oxidizing bacterium Thiobacillus ferrooxidans,
which thrives in a low-pH environment and oxidizes ferrous iron to ferric iron (Kleinmann and
others, 1980). Under low pH conditions, ferric iron remains in solution and can directly oxidize
Geochemical Controls
2-29
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'Coal Rimining BMP Guidance Manual
pyrite. Thus, once AMD formation gets started, the reaction is further accelerated by bacteria and
the production of ferric iron. The result can be severe acid mine drainage.
i IP
(Hill
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Acidity produced by acid mine drainage can be neutralized in the presence of sufficient carbonate
II I ' '''''ii'iLi'l''!1', '' I 1!"!|l"i,ilป ": :' !,,!'!" I IS!
minerals. This reaction is shown by Equation 6, for which it is assumed that CO2 will be
produced and will exsolve from solution. Using this equation, it takes 31.25 tons of CaCO3 to
neutralize 1000 tons of material with 1 percent sulfur. This is the traditional method used for
..; =; : :: , ,,,.,, ;, , ,,=,, :,,; , .,.1, ... . . :;
acid-base accounting calculations. The main shortcoming of this equation is that there is no
"alkalinity" (bicarbonate or HCO3") produced. Under normal conditions, not all CO2 escapes to
', ' ij ! I ' "' , I1'!"!!1!! ' '.i1:: I1"'!1,!! il IIIPI1
the atmosphere. Some CO, dissolves hi water producing acidity. If the reaction product is
.,!'!' I 111 III I I 1*1 * r I , , , . .;,:,;;,,,, -.
HCO3~ alkalinity (Equation 5), twice as much carbonate will be required to neutralize the same
amount of material (Cravotta and others, 1990). Whether it is the process in Equation 5 or
Equation 6 that is dominant depends on the extent of how open or closed the mine is to the
atmosphere.
Where neutralization occurs, the pH can remain near-neutral, inhibiting bacterial catalysis of iron
oxidation and keeping ferric iron relatively insoluble. Thus, the quality of drainage produced by
a given mine is largely dependent not only on the presenceor absence of:pyritic sulfur, but also
on the availability of calcium carbonate or other neutralizing agents in the coal and overburden.
Brady and others (1994) and diPretoro and Rauch (1988) found a strong relationship between the
neutralization potential of surface coal mine overburden and the alkalinity or neutrality of post-
"l i II ' i11 fii '' i ,. i, '.;;,!!,:i: w't'.w rw^ฎTWMt--- rtuif:::v-iT7' fc11:- ' ';' ri-'ivi; ;.:
mining drainage. Sites with more than 3 percent naturally occurring carbonates produced
alkaline drainage. Sites with less than 1 percent carbonate gerierally produced acidic drainage.
Perry and Brady (1995) attribute this effect not only to neutralization but also to near-neutral
conditions limiting bacterial catalysis of ferrous iron oxidation and oxidation of pyrite by ferric
I1 Il11 1IOn' III I M I , :' ,',;,-;"; .; 4 ' ;!:'.,it: fj?.; 'i; . :,ซ*.! :^.;;;l.f.Hi-jf :v ;,:.!;> i Ua.. -;. = 'i I Ill I
NP was found to be a much better predictor of whether a mine would produce alkaline or acidic
1 II || I ill || III II II I III III I '"lit Ji, . i lil. I1'! I'litiiFi1'1! "I; ''Uli/'JI'Liilit ,''' f:'';"" '; ;iii|ปll'!!' ij,.!1,;1! S'^/'iiliiraiik:- 'I,,,:, .''f , "TIHiiil"1 ,' , ' I'll;;!1'111 ', \\ riiV.* i'fllll! Ifft1 f, 'in >
water than was the maximum potential acidity, calculated from the overburden sulfur content,
2-30
Geochemical Controls
I
in
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Coal Remining BMP Guidance Manual
thus demonstrating the importance of carbonates on mine drainage quality (diPretoro, 1986;
Brady and Hornberger, 1990; Brady and others, 1994; Perry and Brady 1995). For mines which
are naturally deficient in carbonates, and therefore likely producers of acidic drainage, the
implication is obvious. If sufficient alkaline material is imported from off-site to make up the
deficiency in NP, the site will produce alkaline rather than acidic drainage.
The solubility of calcium carbonate also plays an important role in whether a site can generate
sufficient neutralization to prevent acidic drainage. Calcite (CaCO3) solubility is dependent on
the partial pressure of CO2 (Figure 2.2a). At atmospheric conditions, the solubility of calcite is
limited to approximately 20 mg/LCa (50 mg/L as CaCO3-or 61 mg/L as HCO3' alkalinity)
assuming a CO2 content of the pore gases of only 0.03 percent. At 20 percent CO2 content,
which has been measured in some backfill environments (Cravotta and others, 1994a), calcite
solubility exceeds 200 mg/L Ca (500 mg/L as CaCO3 or 610 mg/L as HCO/ alkalinity). Guo and
Cravotta (1996) note that CO2 partial pressures vary from mine site to mine site depending on
rock type and backfill configuration. Shallow backfills on steep slopes with blocky overburden
and thin soil cover, for example, tend to "breathe," thereby reducing CO2 partial pressures (Pco2).
Deeply buried backfills or sites with restricted airflow or thick soil covers would tend to have
higher CO2 levels, enhancing calcite dissolution. At these sites, Pco2 tends to increase with
depth. The Pco2 has implications for the placement of alkaline materials within the backfill.
Near-surface placement of alkaline material, where CO2 partial pressures approach atmospheric
conditions, may not be as desirable as distribution deeper within the backfill.
In theory, almost any acid-prone site could be transformed into an alkaline site, if enough
carbonate material is imported. For this to be achieved, however, it is necessary to determine: (1)
how much alkaline material should be applied to ensure a successful result; and (2) the optimum
place within the backfill where the alkaline material should be applied.
Geochemical Controls
2-31
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Coal Reminins BMP Guidance Manual
Ililct a,!:,,,, 'if:
lii "-!*,; '''*;,;
Figure 2.2a: Solubility of Calcium Carbonate (Calcite) in Water at 25ฐC as a Function of
Partial Pressure of CO2 (Hem, 1985)
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Coal Remining BMP Guidance Manual
2.2.1 Implementation Guidelines
Fifteen years of research has shown that alkaline addition can improve water quality and prevent
AMD production, but that failures are common, especially where alkaline addition rates are too
low. Based on these studies, any alkaline addition project should consider:
how much and what type of alkaline material should be applied,
how should the alkaline material should be emplaced in the backfill, and
when is alkaline addition appropriate?
Seventeen of sixty-one mining site data packages submitted by Appalachian coal mining states
(Appendix A, EPA Remining Database, 1999) had alkaline addition listed as a BMP. Alkaline
addition, like any other BMP, is seldom used alone. Table 2.2.la lists additional significant
BMPs that were used in conjunction with alkaline addition at these sites. In a Pennsylvania study
of closed remining sites (Appendix B, PA Remining Site Study), alkaline addition was always
used in conjunction with some other BMP. Other BMPs included daylighting of deep mines,
special handling of acidic materials, surface regrading, ground-water handling, ^nd surface
revegetation.
Geochemical Controls
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Coal Remining BMP Guidance Manual
f! a
lilt, i ';'
Table 2.2.1a: Distribution, Type and Amount of Alkaline Materials Used (Appendix A,
EPA Remining Database, 1999)
Mine,
Type
PA(1)S
PA(2) R*
PA(7) s
PA(8) s"
PA(10) s
PA(11)S*
PA(12) s"
PA(14) A*
PA(18)A"
PA(19) s*
TN(3)S
TN(4) s"
WV(3) s"
WV(5) s"
WV(6) s*
WV(8) s"
AL(10)S
Placement
30 tons/acre applied to pit floor
Alternate refuse & coal ash. 1,650,000
tons of reject refuse, 1,350,000 tons ash
10ft thick layer in backfill. Compacted/set
as cement. Above post-mining water table
360 tons/acre applied to pit floor. 240
tons/acre in blast holes; dispersed
throughout spoil
Ripping of calcareous pit floor material
50 tons/acre applied to pit floor
Within spoil. Compacted to 90%
maximum dry density
In abandoned strip pit. 5 million yds3
compacted to min. 90% dry density
100 tons/acre applied to surface and pit
floor. Approx. 800 tons/acre in spoil
"Spoil side" of dragline bench
2 ft lifts through overburden
2 ft applied to surface. Mixed through
overburden
12 to 18 inches applied to pit floor.
2 ft applied to surface
Min. 1 ft thick, 30 ft wide channel
20 tons/acre applied to pit floor
Type of Alkaline
Material
Crushed limestone
(>95% CaCO3)
Power plant coal
ash. 5.8%CaCO3
Coal ash
Limestone
Screenings
Pit floor rock is 15
to 20% CaCO3
Agricultural Lime
Coal Ash
Coal Ash
Coal Ash, pHll
Lime processing
flue dust
Limestone
Limestone
Coal Ash
Coal Ash
Coal Ash,
pH 10.5 to 12
Other Major BMPs
Daylighting
Removal of Acid-Forming
materials, Revegetation
Daylighting, Regrading
Revegetation, Special Handling
Daylighting
Special Handling
Bactericide, Special Handling
Regrading
Regrading, Revegetation
Daylighting, Regrading,
Revegetation
Revegetation
Daylighting, Regrading,
Revegetation
Regrading
Revegetation
Special Handling,
Chimney Drains, Regrading,
Backfill Innundation
Anoxic Limestone Drains
Regrading
Regrading
;i* Mine is still active s Surface
* Anthracite R Refuse Reprocessing
:""i! i .-si s:
2-34
Geochemical Controls
^^งi! ฃฃ;,; ii::::^ l\,g|i!iyiii
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Coal Remining BMP Guidance Manual
Alkaline Materials
A variety of alkaline materials are available as alkaline additives. Traditionally alkaline addition
projects use crushed limestone or limestone-based waste products. Limestone-based waste
products include crusher waste, kiln dust, partially burnt lime and "off-spec" lime products.
More recently alkaline waste products from other sources have been considered. Chief among
these is fluidized-bed combustion fly ash and bottom ash. An examination of Table 2.2. Ib
shows the range of products being used and the current trend in using coal combustion ash.
Table 2.2.1b: Example Analyses of Coal Ash. (Units are percentages) (Scheetz and others,
1997)
Oxide
SiO2
A1203
Fe203
CaO
MgO
Na2O
K2O
S03
Moisture
LOI
Coal Ash with
< 10% CaO a
52.5 ฑ 9.6
22.8 ฑ 5.4
7.5 ฑ4.3
4.9 ฑ 2.9
1.3 ฑ0.7
1.0 ฑ1.0
1.3 ฑ0.8
0.6 ฑ 0.5
0.11+0.14
2.6 ฑ 2.4
Coal Ash with
> 20% CaO b
36.9 ฑ 4.7
17.6 ฑ 2.7
6.2 ฑ1.1
25.2 ฑ 2.8
5.1 ฑ 1.0
1.7 ฑ1.2
0.6 ฑ 0.6
2.9 ฑ1.8
0.06 ฑ 0.06
0.33 ฑ 0.35
High BTU
Coalc
24
6.05
2.05
42
0.045
0.07
0.51
20.8
+ 0.25
2.03
Anthracite
Culmc
58
20.4
5.74
4.11
0.62
0.59
2.56
1.1
+ 0.49
3.31
Bituminous
Refuse c
34
2.15
5.98
30
0.62
0.11
1.49
13.0
3.70
10.0
"Characteristics of eastern bituminous and anthracite coal
bCharacteristics of western lignitic and sub-bituminous coals
cAsh resulting from burning coal, culm and refuse with limestone
LOI = Loss on ignition
Geochemical Controls
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Coal Rtmining BMP Guidance Manual
Limestone and Limestone-Based Products
The chemical principles of neutralization by limestone are presented above in the section
Theory of Alkaline Addition" and the neutralization reactions are shown in Equations 5 and 6.
Limestone, which is composed mainly of the mineral calcite (CaCO3), occurs naturally on many
jmine sites. An advantage of limestone is" that it dissolves more slowly than quick lime or
hydrated lime, thus lasting longer. A disadvantage is that its solubility is limited, such that
alkalinity higher than -400 mg/L as CaCO3 is rarely achieved. At atmospheric pressures of CO2,
calcite will produce an alkalinity of <100 mg/L CaCO3 (Hornberger and Brady, 1998). Another
mineral'that has neutralizing properties and occurs naturally hi coal overburden is dolomite
[CaMg(COj)2]. Neutralization by dolomite is similar to that shown in Equations 5 and 6, but the
reaction rate in slower than limestone.
''Quick lime5' (calcium oxide)' Ca'6) and "hydrated lime" [calcium hydroxide, Ca(OH)2] are
produced by heating limestone and driving off CO2. These are more soluble than calcite and can
produce a pH as high-as 11 or 12. The advantage of quick lime or hydrated lime is its high
solubility and ability to generate high pH. The disadvantage is that because of its high solubility
it maybe consumed quickly. The neutralization processes are represented by Equations 6 and 7
(Cravotta and others, 1990).
Ca(OH)2 + 2 H+-> Ca2++ 2H2O (Equation 9)
i;;;. ; , CaCJ + 2 H* , -, Ca2+ + H2O (Equation 10)
11:, |i, i. . ", ' '! 'jJIIRiil,;1 II fill , ,;r|!'i ''"''"n.: ' !', i",11:;1 '' -, lull1: , "' 'f ' ' , ' :IL ;;,,ซ, ' ,1!i ''I ill SI 'li'!'!"1 .i1!' I ,""i ,,. I'1 ,i iv '!"':.' '' !l!l ' , SlP ,l,1"1, ii '!'ป' '*li!l,,'l
m :^m i ^ ,*<, m^'& ;.'kr.:!;!':.^^'^^'"^' t-&\-$^$ ^i: i-11 t11: i; -;; ; i i; ; ., ?< ^ \,;.ป:, <;>. ; m f f i :ซ,, ^;: j i ni,: ; ; 'i ปป.; "' ri .:. , w " \ m is ".Mf?;
" ':": '' "'; ; :' "' ' " "'" :"""'''' '"! ;1 " ""'T ' "'"''" " ;v';;""'' ';i'l!|
The purity of limestone or other alkaline additives is an important factor. Many rocks with the
potential to generate alkaline water are not limestones, but calcareous shales or other rock. If a
2-36
Geochemical Controls
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Coal Remining BMP Guidance Manual
rock that is not nearly pure calcite is used, alkaline addition rates should be adjusted to
compensate for the lack of purity. For example, if the material that is proposed for alkaline
addition has a NP of 500 tons CaCO3/1000 tons of material (50 percent purity), twice as much
material would be required to provide the necessary amount of CaCO3. Regardless of the
alkaline material to be used, the application rate should be adjusted to reflect the material's
neutralization potential as calcium carbonate equivalent.
Coal Ash
Coal ash has been used in a variety of ways for abatement of mine drainage pollution, including
the following:
injection into underground mines with the intention of abating acid mine drainage by sealing
(Aljoe, 1999; Canty and Everett, 1999; and Rafalko and Petzrick, 1999),
as an additive to help create a suitable soil substitute out of acidic spoil (Stehouwer and
others, 1999),
as an impermeable cap for reduction of infiltration into acidic surface mine spoil (Hellier,
1998). Ash has been mixed with reprocessed coal refuse for AMD abatement (Foster
Wheeler Corp., 1998; Panther Creek Energy Facility, n.d.),
as a grout to isolate acidic material in surface mine spoil (Schueck and others, 1994),
as fill material for abandoned surface mines and anthracite region "crop falls" (Scheetz and
others, 1997), and
as an alkaline additive to neutralize acidic mine spoil.
The use of coal ash as an alkaline additive will be discussed in this section. The use of ash for
low-permeability caps and seals is discussed in Section 1.1 and its use for grout curtains is
discussed in Section 1.2.
The popularity of using coal ash as an alkaline additive is demonstrated by the fact that it is
practiced by eight of the 17 mines listed in Table 2.2. la. The alkalinity generating properties of
coal ash vary depending on the type of power plant producing the ash. Most alkaline ashes are
Geochemical Controls
2-37
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mm:
vCoal Remining BMP Guidance Manual
generated By fluidized bed combustion (FBC) power plants. These plants burn high-sulfur coal or
coal reject material as fuel. Limestone is used to absorb the sulfur. The limestone calcines
leaving calcium oxide. According to Skousen and others (1997), about one-half of the CaO
dioxide to form gypsum and the rest remains unreacted. The ash can be 10 to
ii!H!!'ปi!' "i. i Bull!1 i iiniriK'i i QIIII,, .; "inn i,,i i. , i. ; u f, - m, . ; ' it/'i it v /.i.'. nn'in *.v ) i- ij*,,: v- , i wi iv HIW i i n IIIWIIMI I'f'ij-ii,, BK"* > u i > 'ซ ป '," w
20 percent calcium carbonate equivalent. The amount of limestone used can be substantial. For
example, the Colver, Permsylvania, power plant bums 600,000 fbhso^^^ refuse)
i'i; i Wl 1 ' " "
(jeiiiei^itious behavior. The cementitious behavior is activated by alkali matenals. The making
";;::"",,':;:';,; ,,':"";;;,,;;'of cement"!^ dates'back to'the time" of the Romans. "Many of these
|'sjhlctures'alp; still standing today (Scheetz and others, 1993) which is testimony to its durability.
ii i;: n i .f, '' "iiiS mtii'l iil'Li1 iiiiii liiiiii!* rTsst "' ;iปi;:l ' ML:i sซm Sf ,s .1 t ' t-. :; a '!. .1:!::., w';" j msf :-.MKm .tuiw; aa ;K: . =iafa: >ป;, asr' s
i-.ii l
Cementifious behavior is an advantage if one is proposing ash as a grout or an impermeable cap.
ซ f 11 i i i I
Scheetz and otibiers (1993) list the following "advantages" for the use of coal ash for cementitious
1 i"ilBB,!l!i; 'ซ' IBB,
i .1 ! IfS'ii:? l:S!!li!HI!
!!:;,!*,,; ; _ low.cost of raw materials
K;K.^': 'l"'l' ' !R ' '''g^utsc^
"::: " --" '' : : " '":"'": L""' "'"' :":";:' ':" :'"'" :; :' ;' :" ; " ' ' :: ' ' :' ":":"': : "l
|roiits have low heats of hydration
"'.rr1.:. ^" V"^ ,,'grb'uts are less soluble'than portland cement-based materials
;^';'~!;-:"--^ !"' !!;>!::'',gfSu;ts; cM'bV'iess'permeable than portland cement-based materials'' .'
BBIIBU IBIBIBiUilBBB, < ":"!">ป 1IIIIK!:;'!1"!1',,! < BlIINI'l I'M;,! 'IIIBIIIBillll! E !" ^illBIIBBB.Viiiiiil.i.WJiiff'lBiBi,: ซiป """UliiiLi ll/IBBI I' 'Mil, '! i: lliT'iftV11!!!**1 !ill!l"!ป,l: iซ inuili I'l'i'li n|ซ I' nWi'll!!! :' Jill Bl !!liiiillIIB'w1JI!iiBBI!|'B,!i:i,'''!iH"': 1 "V ,,Bi. I'll 'Vl'l',, "'i Af
Mป^V ;* ปyuซป gsggfg 5^ be activated with alkali chlorides and sulfates.
Li "III"1 .ilj'il IP'!,, , jllll, ','! li,!,! ,,|, |!i uhllKllllii !'! ""!||l|l !!!,; 'i/l,1! ,|
.. Iff1 'Mill? 'iiv.ji' '!." W&itSSUf iiB'!-"',' I
j^:LปMiaft; ;;i;a.. ฃj|y^ariy of these same properties that are advantageous for impermeable grouts and caps are a
,::"!:;;,;- ;': ';;:: --disadvantaae for its use as "ah 'alkaline' additive. For 'example, low solubility and low
Illiiltli, ''!'l'i|||iii!!J'' ^illWIII!' '; '!'!;"" i,',. IllllN I:1 ', I i (T * "id Jilll llllli " "M.S iSr , .. . .
1 jiiiiij in ill ">ri i fi!' i: (*IK i imtm ^m* s jiii!i,t; ii11 j w-t;; ;.. - v
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Coal Remining BMP Guidance Manual
content of the ash" (Scheetz and others, 1997). In other words, the lime portion of the ash is an
activator that can make the ash into cement.
Coal combustion ash, if it is to be used as an alkaline additive, should be evaluated for its
calcium carbonate equivalency and its cementitious properties. It should be spread and mixed
with spoil so as to maximize its surface area. If not adequately mixed, the ash may set up as
large blocks of cement with minimal surface area for reactivity, thus resulting in an ineffective
alkaline additive.
Coal ash, even with pozzolanic properties, has potential as an effective "seal" on acidic pit floors.
This application would also provide an alkaline substrate for spoil waters.
Other Alkaline Additives
Information on other alkaline sources is scarce. Skousen and others (1997) briefly discusses the
use of steel slags and states that these slags often have NPs from 45 to 90 percent, but warns that
slags "are produced by a number of processes so care is needed to ensure candidate slags will not
leach metal ions such as Cr, Mn, Ni, or Pb." Phosphate rock has been proposed for use as an
alkaline additive, but no full-scale field projects have been commenced and the cost is high
(Skousen and others, 1997). Phosphate rock can contain significant quantities of calcium
carbonate. Thus it may be difficult to determine the relative effectiveness of the phosphate
relative to the carbonate. Other alkaline additives or alkaline-producing additives mentioned by
Skousen and others (1997) are AMD sludge and organic wastes. AMD sludge is the waste
product from mine drainage treatment. Lime-treated floes can contain up to 50 percent unreacted
lime. Field results are limited. Organic waste is different from the other alkaline generating
processes in that it does not directly impart alkalinity. Several species of bacteria can obtain
metabolic energy by reacting sulfate with simple organic compounds. In the process sulfate is
reduced and bicarbonate is created (i.e., alkalinity). Stalker, Rose and Michaud (1996)
performed laboratory studies on a variety of organic materials. The rates of sulfate reduction for
Geochemical Controls
2-39
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Coal Remining BMP Guidance Manual
cellulose materials (sawdust, pulped newspaper & mushroom compost) were slow, but for milk
products (cheese whey and lactate) the rates were more rapid.
Application Rates
Published studies on alkaline addition primarily examine mines in the northern Appalachian.
The transferability of this research to the southern Appalachians is not fully known. The
I
overburden in the southern Appalachians is typically lower in sulfur than overburden in the
northern Appalachians. Field studies of alkaline addition in the northern Appalachians appear to
be converging on required application rates. The amount needed to produce alkaline drainage is
approximately 1.5 to 3 percent CaCO3 equivalent for sites with low to moderate pyrite content.
This application rate appears deceptively low. One percent CaCO3 equates to approximately 37
tons of CaCO3 for each acre-foot of overburden. A 100-acre surface mine with an average
overburden thickness of 50 feet needing 1 percent additional CaCO3 would require 183,500 tons
of added alkaline material or 1,835 tons/acre. Thus, the feasibility of an alkaline addition project
Usually becomes a matter of economics as well as science. The challenge is to determine the
"Ilil'l |i'ii|i'|iji'. fjii" .L ',. J " , . , .ii '" . , i'.1 . J. ii I .,. ,
minimum alkaline addition rate which will still be effective in preventing acidic drainage.
It
i
Using data from Brady and others (1994) and Perry and Brady (1995), Tables 2.2.1c - 2.2.1f
show overall NP and NNP requirements in order to produce alkaline drainage using acid-base
l
accounting data. In all cases, NP and NNP calculations are made using the method described by
Smith and Brady (1990). Total weights of overburden, NP, and MPA are determined for each
.llii i" ,,!!" ii'it'i!' ; ', if ',,, ii,;,, 'liiiiSjlf tJS^^^^^^ 1(3!!' :":ii,i!"!,,!" iiiif ., IB,! f'P; a vr /-i ",! ,""' ! .';'?! !;' i1'1'jl'iWft'-S1, v'IF.i, ll'SkW* ,!*", !)!:i!!i"l!| l!'-"'V"' '!' ': .f;i!''T''i.. "< ~-!i '!' ' i-i'lS" ปi!
drill hole fnterval, 5^se(| on an approximation of the areal extent of that interval and unit weights
ijfpjCovgrjjurcfsn ipate.rials. Tjie total weights of the coal intervals are multiplied by a pit loss
as;,,*, 1' BL I ,i'ii ,,,,l 11 , Illlfil,',' t/,', ,'i!'i Jill, il'iiillillll' ,i 'IJiililill .M'lilili",'!!,.'!,, ,11 i :,'',''IK,,'!,,,,! ,;, I",,,",; .in , 'T,' ;"', I,,, it ', ' "" ," ,'I," I'.ill'II, l!l,i,l'Hi i' l! ,i|,'i ill ' ,,"lltiiiii,,'Illll,,, l' ii'llfl, ' ,!'!"! Hi''' il i',' ','1:, ' '-i II1,.' ' ..it "', ,, i
factor of 0.1, assuming approximately 10 percent of the coal will be lost in the pit and not
! li"'!1!'!!'!" I' i'll'l"il '"''ill''"." '''i i|l||i|!'1i|''.i;f'ii''i!!|i|ii''"'!iป ifSlllllW III1' "''II1!1' ''.' ' "' 'THiiiiii 'ป'i M > i n'!i iป ? i ' ''M'I i i iii'. 'Hi'. M .iiiii ii "i in.'"i ".,. in. H. ii ii..i.."..ipi ' iiiiin' .MI ... ...
Sremoved. A higher or lower pit loss factor can be used if warranted by site-specific conditions.
The uppermost 0.5 feet of strata underlying the bottom coal seam is also included in the
ca|cu|a|ipn. These quantities are summed to determine the total tonnage of overburden, NP,
:MPA ana to represent the overall NP, MPA and 1WP m parts per mousand as Cac63 to
2-40 Geochemical Controls
umiikSf in iiiiM^^^ iiiiiBi' i iii 11 ii iii I ii 11 ii iiiii iiiii 11111 iiiiiiM iii iiiii i iiiiiiiiiiiiiiiii iiiii ii iiiiiii in ii in i iiii iii ii i i i ii in in i iiiii iiiii
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Coal Remining BMP Guidance Manual
Multiple overburden holes are combined by considering an area of influence of each hole using
the Theissen polygon method (Smith and Brady, 1990).
Table 2.2.1c: Percentage of Sites Producing Net Alkaline Drainage by Net NP without
Thresholds
Net NP (ppt CaCO3)
<-10
-10 to 0
Oto 12
>12
Number of Sites (n)
1
11
17
10
% with Net Alkaline Drainage
0.0
18.2
58.8
100.0
Table 2.2.1d: Percentage of Sites Producing Net Alkaline Drainage by Total NP without
Thresholds
Total NP (ppt CaCO3)
<5
5 to 10
10 to 18
18 to 22
>22
Number of Sites (n)
3
9
10
7
10
% with Net Alkaline Drainage
0.0
33.3 .
50.0
71.4
100.0
Table 2.2.1e: Percentage of Sites Producing Net Alkaline Drainage by Net NP with
Thresholds
Net NP (ppt CaCO3)
<-2
-2 to 6
>6
Number of Sites (n)
14
14
11
% with Net Alkaline Drainage
28.6
57.1
100.0
Geochemical Controls
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Illlllll 111
( II i IK
Coal Remining BMP Guidance Manual
Table 2.2.1f: ' "Percentage of Sites Producing Net Alkaline Drainage by Total NF'w'itE
Total NP (ppt CaCO3)
<2
2 to 9
>9
Number of Sites (n)
12
12
15
% with Net Alkaline Drainage
16.7
50.0
100.0
L
When all acid base accounting data are considered (i.e., there are no significance thresholds), an
oVerall NNPgreater than 12 ppt CaCO3 or a'NP" greater than 22"ppt CaCO3 is very likely to
assure alkaline drainage. Based on these data, a conservative approach to determining alkaline
addition rates would require application of alkaline material at a rate equal to the difference
between an overall NNP of 12 ppt CaCO3 or a NP of 22 ppt CaCO3 and the actual premining
overall NP or NNP. A site having a NNP of 2 ppt CaCO3, for example, would require the
application of an additional 1 percent CaCO3 (10 ppt). An example calculation is shown below:
Tons of overburden: 1,000,000 tons
Acres of mining: 20 acres
Average Net NP: 2 ppt CaCO3
Deficiency: (12 - 2)ppt CaCO3 = 10 ppt CaCO3 = 1%
Tons additional NP required for Net NP of 12: 1 % X 1,000,000 tons overburden = 10,000 tons
: "v: ":" i|:i"-';i '" ' '::: ;::' -'''" Y'"'' ; ' r"";'"":' ;i'- -
Tons per acre required: 10,000 tons / 20 acres = 500 ton/acre
A'dlustect for alk'aline material with 80% CaCO, equivalent: 500 tons/acre / 80% = 625 ton/acre
!* ,, '1,: S '1 !'
Similarly, where significance thresholds are used to analyze ABA data, a "safe" alkaline addition
rate would bring the overall NP value above 9 ppt CaCO3 or the NNP above 6 ppt CaCO3. I
i'- 'I, ,,' ซ -I llHliii -,, , . . r>... ,,' ,, , .. I i- ft. ..P..' : ", I I!, I
,
.:,'",'l! " 11' lilt i, r,!,: W1' ' 1,,'siill
Traditionally the Commonwealth of Pennsylvania has required most alkaline addition sites to
produce an overall NNP of 6 ppt CaCO3 with thresholds. The success rate for sites with this
1 ;i" if Clllil1 ', |.' 11': . ft!!1.' ': !!l|ni ly, ' !::!ซ # ซ'' . " , I11 : J! ' ' .. t:. !t' , in ' Til Hi i., -- 1, ji , A1,ป, '" !, Hi II:' 1 1,! ? ! ," ' HI i iii'i, i,:''": ,;" ' i' i II,: u'' ' . ,":' Hi,. . .If
application rate is risky at best with only 59 percent of sites in this class producing alkaline
2-42
Geochemical Controls
ill 111 ' i IIP
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Coal Remining BMP Guidance Manual
drainage (Smith and Brady, 1990). To a great extent, the selection of the appropriate alkaline
addition rate is determined by the risk of failure that can be tolerated, as well as by the
availability and cost of alkaline additives.
As more data are compiled, the ability to accurately determine minimum alkaline addition rates
needed to obtain alkaline drainage should improve. Also, based on the limited experience to
date, most alkaline addition projects using more than 500 tons/acre as CaCO3 have been
successful. Except for sites with very low sulfur, alkaline addition rates less than 500 tons/acre
have consistently failed to produce alkaline drainage. This is based on a small population of
alkaline addition sites (~5), none of which contained the worst possible overburden. It would be
premature to conclude that alkaline addition of more than 500 ton/acre will ensure success on all
sites or that lower addition rates guarantee failure.
Materials Handling and Placement
Most successful alkaline addition sites have employed thorough mixing of alkaline material
throughout the backfill. This can be done using various methods. One innovative and effective
approach is to use the alkaline material as blast hole stemming (Smith and Dodge, 1995).
Depending on the material being used and how well it packs, it may also result in more
effectively directing the blast energy at breaking overburden. Alternately, alkaline material can
be placed on the surface of the overburden where it will be subsequently redistributed following
excavation and placement.
Another method of alkaline addition is to place the material on the surface of regraded spoil and
disk it into the upper portion of the spoil. This approach usually is used either in combination
with mixing in the backfill or as a remedial measure after the site has already been backfilled.
Although it was originally thought that this method would take advantage of the added alkalinity
in the most active zone of AMD production and create an alkaline environment, inhibiting AMD
formation, most projects employing only surface application have not been successful. There are
at least three possible explanations: (1) Dissolution of CaCO3 and the production of alkalinity at
Geochemical Controls
2-43
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'19(11 8! i:>III(t i:/ !'
..... :: iiiiHiiii ...... aitmt i 'fviiiiii
Sill
" ..... wi MX f w. " ซ i ........... wv ' ! " a; : ...... i .....
'I1-:".:! ...... "" ..... :f; "!"; ....... !":;!?' ="":;:
'" ' '" ' '
1 ...... lilllllRI' 'iV.'I'S'ii' >!|l!lilllR W lIR'JIIIill ..... IS.,!'
IS - ..... Si '? '
i! fell Jill'!'"11
,
S' if ''.'.
, 'll'IB'I'i*"1'!1:!:, ' *M','t 'MIFlU ..... illtflinilllilt'1 "i"1IEiB!i " ';i ""liS I
"
Coal Rsmining BMP Guidance Manual
near surface conditions is limited by the partial pressure of CO2. Typically, the maximum
alkalinity which can be achieved under thin soil cover is approximately 75 to 150 mg/L, (Rose
i ii MI i iiiii i II i ' i in in i I i i
and Cravotta, 1998). This greatly limits the effectiveness of near-surface alkaline material and
II I I I Mill IIIII III Illllllllll III I I 111 II I I II II I
usually does not produce enough alkalinity to neutralize acidity generated elsewhere in the
backfill; (2) Mine spoils do not transmit water as a uniform wetting front (Caruccio and Geidel,
1989). Rather, surface waters tend to preferentially infiltrate the spoils at the most conductive
areas, effectively bypassing much of the near-surface alkaline material; and (3) Contact of
limestone with acid-producing materials is very limited in the surface environment.
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The earliest alkaline addition projects involved spreading all of the alkaline material on the pit
""" ............ ......... ................... ' ................ ' "' ' ' ...................... '' ................... ":I" ...... ............. ............ ' L ....... I ......................... ........................... '"' ...... ............. .......... ........... ...... ............... " ......... Mi ............
floor, prior to backfilling. The assumption was that this portion of backfill was the most likely to
be saturated, allowing the alkaline material to neutralize all of the acidity produced. These sites
tended to pjoduce alkalme drainage initially, which soon changed to acidic dr^ This is
prf Sumably because the pit floor environment was not anoxic and the alkaline material became
i|| ' i f'Jjj. : . '"", , ITJHft ' 'Si I,.1 f ; If $ ........ fat " ii '!l ffi. Ii' "I'! ' '!" J : " S ' 'Ii "l" i!! / ' : 1: '"I i " '( I'1'"'1!11111 '"'fi i*'1!!, ' '''^ !'' ;: Its J ' -l':s; i;!"; i'-J'lli;:1 ' ' , """' it ' ; " "''"I' - r!; " ' f ':| , i 'ft .!: ....... ) Hill1' ' Si"'l '
jlnefllc^ive ...... du^ ...... to .armoring with ferric hydroxide precipitate. Alkaline addition to the pit floor
'""'"Sti'll has' utffityj1 howeverj wheri'there is a need to neutralize ''j1|gg:sujฃu'r1p^1ฃ|oor_ ...... jj ^g p|t fjoor .................
is saturated, and iron remains ferrous, calcite on the pit floor should function as an anoxic drain
If M, I! fV'UffiiM.' sflliti;, iilSlllll ,,,i,S|'i:H,'i, ,1 i!,:'! '" nl till" ,:,: SI' i > -, rt.' ;.:. ;,',: 'Ill " IP' iSป; ,' b ',,,,1. Mil, it""'; I!', : ',",', .'i is i",i" ,i -,,.' ' ,: "i',,i ' :
neutralizing acidity. Putting most of the material on the pit floor fails to take advantage of the
inhibitory effect of maintaining a near-neutral pH within the spoil environment. There probably
is little utility in application rates of more than 100 tons/acre to the pit floor, although at least 20
tons/acre should be applied to provide complete coverage. Again, the key appears to be getting
i jj,
the alkaline material mixed throughout the spoil, especially throughout the more pyritic material.
t "" ' '
[Alkaline addition is frequently implemented in conjunction with special handling of high-sulfur
zones, where high sulfur material is placed in pods and isolated from percolating ground water.
Ill III INI I Illllllllll IIIII11 I I I ill I ill1; , i , " - ill!1 III: I, ; . '''I"'If "!ป; ' ,'iil i!1 :, i lilh m'",,;i 'i ' < illllii'lPilllllli" M 'lill'1, HIHl1"; u| I , ' '" " K"" I,],, :(, Jllp1;..;!! '|>, ' i1, f 'i" 'I'll1' I'l'l '''I'llMIIll1, llik.i "
Alkaline material can be mixed with the high-sulfur material to prevent AMD formation within
the pod and can be placed in conjunction with a cap to enhance hydraulic isolation and to help
ill nil i iiiiiiiii 11 iiiii i I!;',1!,"!, I l':"'1' j1?!'*1!";!/ ['' ', if"",'"1: '::.'!is!i':l,"'ili!'-l ii'iilsi -^t .! JirJW1''.!$; "If fjli1!' ;i|',i, '"'$".> ''tm'""' ''iiiiii: -'A
rnaintain an alkaline environment near the pod. Observations at the Kauffman project suggest
viol -i1:'!), f is;1 ;i liiiM Ml iiin,'
that lime kiln dust may actually cement the material, inhibiting ground-water flow (Rose and
others, 1995).
' 2-44
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Geochemical Controls
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Coal Remining BMP Guidance Manual
The use of alkaline addition as part of special materials handling has not yet been fully evaluated
although some demonstration projects are underway. Recommended procedures for handling
imported alkaline materials have undergone continuous modification as more is learned about
AMD prevention and the interaction between acid-forming materials and neutralizing agents.
Currently, the recommended procedure is to first ensure that enough alkaline material is
thoroughly mixed within the backfill. In addition, smaller amounts of imported alkaline material
should be applied to the surface of the regraded backfill. Applications to the pit floor should be
limited to isolation or neutralization of a high-sulfur pavement, and to no more than is needed to
provide sufficient coverage. Unless the remaining spoil is clearly alkaline, sufficient alkaline
material also should be retained for distribution throughout the backfill.
Alkaline Redistribution
A practice similar to alkaline addition is the redistribution of alkaline materials to alkaline-
deficient areas from areas of the same or adjacent mine sites which have more than ample
alkaline strata. This procedure is practical where sufficient quantities of alkaline material are
present, but distribution is so uneven that some portions of the backfill do not contain enough
neutralizers to prevent or neutralize AMD. Alkaline redistribution then becomes largely an
exercise in materials handling. Alkaline stratigraphic units should be clearly identified,
segregated, transported to the alkaline-deficient area, and incorporated into the backfill.
Depending on the quantity and characteristics of the alkaline material available, it may also be
necessary to crush the material prior to redistribution. The obvious advantage to redistribution, if
it can be done, is the ready availability of the material and the low or zero cost of transportation.
Michaud (1995) developed a mining plan for a proposed surface mine where alkaline
redistribution was fully integrated into the operation, minimizing the need for stockpiling and
rehandling of alkaline overburden. Through the implementation of a complex series of selective
sequencing of cuts and multiple benches, the handling plan provided for redistribution of alkaline
strata, which existed only in limited areas and stratigraphic intervals throughout the site.
Geochemical Controls
2-45
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Coal Rdmining BMP Guidance Manual
I
Through this approach, thorough mixing of alkaline material could be achieved while avoiding
the need to identify, segregate, and redistribute specific geologic units, usually the most difficult
part of a spoil redistribution plan.
in
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Alkaline redistribution has been successfully employed on several surface mining sites that are
currently producing alkaline drainage. The Bridgeview "Morrison" site in Township, Fayette
I ' '"
County, PA, had abundant calcareous rock over most of the site with NPs as high as 700 ppt
CaCO3, but more typically in the 100 to 300 ppt CaCO3 range. The site included two areas of
f ':,:"
about 5 acres each, containing shallow overburden and lacking calcareous rock due to erosion
and weathering. Alkaline material from the high cover area was transported to these low cover
areas. The resulting post-mining water quality from the areas was alkaline.
The Amerikohl "Schott" site in Westmoreland County, Pennsylvania, had calcareous rock on
II
only about 8 acres of the 38 acre site. Originally four acid-base accounting holes were drilled.
These were supplemented by additional holes drilled to determine the lateral distribution of the
calcareous rock. The calcareous rock was removed during mining operations and incorporated
into the spoil on all portions of the mine. Waste limestone was also placed on the pit floor at the
rate of 100 tons/acre. Four years of post-mining water quality monitoring data shows the water
to be net alkaline with alkalinity ranging from 10 ppt to 138 ppt CaCO3.
"Alkaline Addition as a Best Management Practice on Shallow Overburden
In many cases, relatively low (less than 300 ton/acre) alkaline addition rates have been employed
on mine sites that indicated a relatively minor potential to produce acid mine drainage, but were
lacking in significant calcareous strata. Although these sites commonly have low sulfur contents,
they frequently produce mildly acidic drainage due the, lack of any significant NP. In other
cases? alkaline addition was used as an added safety factor to assure alkaline drainage. Alkaline
addition has proven to be an effective "best management practice" for these types of sites.
Ill I Kill I1 III IHI i 'I In
2-46
Geochemical Controls
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Coal Remining BMP Guidance Manual
Often, mine sites with shallow (less than 40 feet) overburden have had calcareous minerals and
pyrite leached out by weathering (Brady and others, 1988). Since easily weatherable minerals
have been removed, water flowing through the overburden material picks up very little dissolved
solids and emerges essentially with the characteristics of rain water. In Pennsylvania,
precipitation typically has a pH less than 6.0. Thus, post-mining water from weathered
overburden may also have a pH of 6.0 or less. The addition of alkaline material is needed to
ensure alkaline post-mining drainage. An example of this implementation is described in Case
Study 1, Section 2.2.3.
2.2.2 Verification of Success or Failure
A critical step in successful alkaline addition is to ensure that the alkaline addition plan is
properly implemented. Both the amount of material to be applied and its distribution throughout
the site should be appropriate. Because of the large quantities of materials involved, careful
record keeping of each shipment of alkaline material and calculation of the quantities of material
distributed is needed. Depending on the method of mining, quantities of alkaline material to be
applied or distributed should be tabulated for each individual cut or phase of the operation.
It is necessary also to periodically retest the neutralization potential of the alkaline material being
used, with a frequency determined by the variability of the material.
Inspections by the regulatory agency of sites with alkaline addition as a BMP should be frequent
and detailed enough to document compliance with the mining plan. An inspection checklist
identifying key aspects of the plan will be useful in many cases.
Implementation Checklist
Recommended items to be considered during the permit review process include:
Site-specific overburden data should be available for determination of the amount of alkaline
material.
Geochemical Controls
2-47
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* :'""" The site-specific overburden data should be representative of the mine overburden. This will
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Thg plan should be feasible in the field, not just on paper.
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RecomJiiended items to consider in an alkaline addition implementation inspection checklist
J*!!!*11*1' 'S'"""'''!! ! ""'I!1,',, I,,!1!" iiVii'11!1!!!!!!!!,!! ,,'i!!!!C!,,, "'! ' ' ' ','' '!;,!""!'' '!"!!"!"' .1!!'''!!,,!!"! t '!'; '" "' ,'' '',,,'''!'!,!!!', II,!!',,;!, ''' ,' V ' ' i:!!'!!'',,"'1"!;"."",!','"1"''!!'"'" l! '"I1'1 :,!'' i! ''"!!!",!lh;!',! Ill,,!; '''.fI,,,!;,,!'! .IIHI!1!1', ||.,!!'"';!'!' ! ,! ' ,11'' ',, !'i.'!i!i''!"M. '!',' ' '''!!!'"? '"!'! '";, ,1!.','''! !!''!!!!!!!!!!!"; .
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include:
i
^V ;f, I)oes what is being done in the field correspond with the plan that is specified in the
permit plans, as shown on maps, cross-sections, and hi the narrative?
11171:111:/''i : 'ป ; i""1 iMiffiD,:1 iiiiiiit':'i11*11'' !"!, ,;: :KJ M',;, ,iiVI ซ,,' ' B; i1' ,:'',, ',",' i,1!;:''1!:!1',:'! ru i,,,1"''," ;, 'i'"1::11'!1; : ',ป:n\! '*, 'iii''1'1!"1"!!1,, i,,:1'1', , ii:,11" I iiu,:1 , ,i,,ii,;, '6*ii'i!L :,i LI, ,>::*?
*, |s the appropriate equipment available?
Is the alkaline material being placed where specified?
nil!!'1:!!!',ป! I',,,,!'i,, i ', 'M,ilf "''l| I,':1:1 rnirilllllllllllllll1 ! Ililllllll1" 'il'Hlli'i'i1 : : HI"lllil|l|| !MTl, ii'M1 ,;l|"llM '',! ,!;,'"": t^T, A.III ,', ,'i MI , , ",,'T1, i i,v',,, -MO,' H ,n< ป ' n ,',:" ' in ,, , M,,,,,, ,,
# Is tfie alkaline material being brougnt to the site the material that was specified in the
F! i, :;i;.:"'; 'i*^ ic 'wSK-: II'". *i";:'!' ""'":':.; 'I''"',;; i'i > :4.. i':': ; "'''"; .':';i 'i", ''" ffii;' ilCs1 "t&i'ii M,fปl v i iris' l; ii:! i i i"::i <:'S c"' WH f '": .si i'l':
it,,,^ j::;'i|^jpef|i^tplan?
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liE slips or other records available to verify the amount of materials being
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;iv iiiil.,!!; "i1'!1 'IIB'flll';), ) ..'SMI'Srii,'"! 11 Sill!1,', , , ,ซ "i", ' 'Ji ''. ' ",; * It *:' I'll
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IRi |||, )!" H M'""!;1!!"! illllllllii1'1 ,HKI,I1I II' " ซ I"",':,' ,"'"',,I TT >,ซ.!'ป! '" ,'i*^.!!SWr!1St''3i3f'.f.";;1 ..... ill ..... U ..... iป^^ ..... KPM1; afi;1*,.:^' 3 ..... L"ffi:i ..... t..
''JfpEffiOrted alkaline material as a method of preventing the formation of acidic drainage was in the
it flap;, nm ..... 'in?. ซ; ii; 'mw i -M '^.^, t& ;:- $ : * r : I'm i! ..... ftiMViii'!' ', j,1! ini-li'i'i, ,' I, i; Ilili ...... < ill > lihlililll ' i'llllt "III Illlll iili, -,','::,,'", J JJ',,'!!,"!''!1:1,!!!'!!',!!" ' Mil'lil,1 f J'l ,.."'! .'ii'ii'i'iiVljil,, |, J
Operation in Surface Mining of Areas With Potentially Acid-Producing Materials (1979). The
Guidelines recommend that alkaline material be added to the backfill at the rate of one third of
any net deficiency in neutralization potential as determined by acid-base accounting. However, it
is uncertain as to why this rate was selected. Many sites with alkaline application rates based on
i in i ....... rr i ....... i ........ 111111111111111" ' i ...... liiii ...... i fli
this recommendation have subsequently failed and are producing acidic drainage.
]
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'2-48
Creochemical Controls
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Coal Remining BMP Guidance Manual
Waddell and others (1986) used alkaline addition to abate acidic drainage resulting from the
construction of Interstate 80 in north central Pennsylvania. The Waddell study involved surface
application of limestone crusher waste and lime flue dust at the rate of 267 tons/acre. It
improved pH values from 3.9 to 4.4. Sulfate concentrations were also reduced, indicating that
the alkaline addition not only neutralized AMD, but slowed its production.
Geidel and Caruccio (1984) examined the selective placement of high-sulfur material in
combination with the application of limestone to a pit floor at the rate of 39 tons/acre. Although
the treated site initially produced alkaline drainage, the drainage soon became acidic. An
untreated control site produced acidic drainage throughout the same period.
Attempting to abate acidic drainage from a Clarion County, Pennsylvania mine site, Lusardi and
Erickson (1985) applied high-calcium crushed limestone at the rate of 120 tons/acre. Although
NNP deficiencies at the site ranged from 25 to 590 tons/acre, they assumed that most acid
production occurred near the surface and that it was necessary to add only enough limestone to
balance the NP deficiency in the upper two meters of spoil. The limestone was disced into the
upper 1.0 feet of the spoil surface. One year after application, no substantial neutralization or
inhibition of acid formation was noted.
O'Hagan and Caruccio (1986) used leaching columns to examine the effect of varying rates of
limestone application on alkaline and non-alkaline shales.. A sulfur-bearing (1.07 percent)
noncalcareous shale produced acidic drainage when no limestone was added, mixed neutral/
slightly acidic drainage when 1 to 2 percent limestone was added, and alkaline drainage when 3
percent or greater limestone was added. Following longer periods of leaching, the shale with 1 to
2 percent limestone produced consistently acidic drainage. The alkaline shale produced alkaline
drainage regardless of whether or not any limestone was added.
By 1990, there were enough well-documented surface mining operations that had employed
alkaline addition to allow an extensive review of the effectiveness of alkaline addition in
preventing or ameliorating acid mine drainage. Brady and others (1990) examined 10
Geochemical Controls 2-49
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lia mine sites. Of these 10 sites, 8 employed alkaline addition as a means of
preventing postrnining AMD. Six of the eight alkaline-addition plans failed to prevent AMD.
The sites which were successful in preventing or at least ameliorating AMD had several things in
E'ji;', ;;,:; 'T'liHi!''='|iii iWiU'A1 !:ซ., Ti'" ;.v -, ;,' ' r. i'"*'1 ', <.'K ..,[, K- ".ป: ,"ป; fiSiS",';1 ifi vis idi.i.ttfliii!1: man i.,, ''ซ ,fKm iiii
c:งmmon:|l) alkaline addition rates were among the highest (500 to 648 tons/acre) and exceeded
:'; I*: i I;!'' i!' ''$ Si'' ~3iti" l!"i fell "* J'i':' ' i 'i".' 'i.i.i'li'1'1 'till'' ill,; ' I1 'iiiii,!'' ''!'' 'ii;! i: ill<(' t11 i'f Si; P" I" -, M- *fe < - MM'. / f vill iiii jiJ*-": iiiii;,i X>lf,;. 1 .ป -li i . * III 'i ill iili" ,,i
fpe'rmit requirements, (2) pyritic materials were special handled, (3) backfilling was performed in
"iill !Uu"W"'iii'iiSii!'"1'Iili;"1! 1911 ;,{i,;:' ii;;-,''fii,''i.S iBi" W "' I/Lif"! 'ฃ lii S",i"V>i-:?'i"">ป-i' I I '"."&''& v" f i ft'f'M-'W |Vm-'W '":""H,! i!:::, >'<' :ป'f WIS- lilii111
'IS .'i':::''1;?*! iiJiM!i(i Hill; I
a timejy manner, and (4) some potentiallyacid-forming materials were removed from the mine
site. Tin? sJiidy concluded that most unsuccessful attempts at alkaline addition were too
conservative in terms of the application rate, particularly the practice of applying one-third the
calculated deficiency. Further, alkaline addition is most effective when incorporated into the
backfill concurrently with mining and reclamation and when implemented in conjunction with
ifo^ ' "l "' ' '' " "'
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' of the use of acid-base accounting for predicting surface coal mine drainage quality
(Brady and others, 1994) showed a strong relationship between the presence of neutralizing
i" lit,, !' ri' '" ,:'l!!lli|!llii"ii'!! i, ''llllilil ' llilll ' , J-r (;,,,",; I,}!'.,{;", ''I!' ii I; i tS i;;' i,1" i!' i, ..> - '} ii, a' , '"""'", ::"!''":' I" ii|i',ir; ;;.?;;;: ail|,i' ranri ii:' .''i J I ii linn '" ,! :,, ' "ii"i,,';,( '' f ฐป , K t
|||,"|i, j, ^ i", ,, ill '"!ป" i Uiilliliilliini,:'!'"', iidliiliiiilliliiil, ' llUillii,;'," i, I!'lii,lliii"il i"i"!< ! ' fi i !!,, !!!!' T 7 ;,, I1!" I "il iltii , ,i,m ' , >,;, ,,i ,m < , , M ,nn .IP, N,.,
Mtip differently than native alkdine strata, the application of alkaline material at a rate that
I. simulates a naturally alkaline site should assure alkaline post-mining water quality.
i
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Skousen and Larew (1995) studied an alkaline addition project that imported alkaline shale from
| j ' i':",'" ,;i lii,=iii, 'fliliii "... flit i "si I1""!':' ',:"' .:,, i;C'i' ,ii-, Si:' ' r;".; " , !,:: W ,1!'!; .r * i: , , i;" &? ,,,i :;, $&;*: I'liiifS: *:$:$& I, liij'^.;^^! :i iffiir1;,:1'". I v" I * 1>S' ปf
^ nearby rruning operation to an operation that was deficient in neutralizers. Although the
|aei|ci^npy calculated from ABA data was equivalent to a one-foot thick layer of the'alkaiine ' "''""
Shale, 3 to 4 fee| of shale were actually imported. Significantiy, for this discussion, the alkaline
addition project successfully prevented AMD.
.I'lllllli'ii'i,,1 1 idii ,
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Perry and Brady (1995) found that overall NP values in excess of 21 ppt CaCO3 and NNP values
-' iFgreater than' 12"ppt CaCO'3" wbuTdi produce" net "alkaline water"" Oyeralf NP"and NJNP values'less '
fi'.'E.!!'1'; I!..'l'!,r-!:;:J iiii t[i,:,lii: '; :^i iii!"is
! 2-50
Geochemical Controls
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-------
Coal Remining BMP Guidance Manual
than 10 ppt CaCO3 and 0 ppt CaCO3, respectively, produced net acidic water. Variable water
quality was found for NP and NNP levels between these limits. The same water quality data
were examined using significance thresholds. Sulfur contents less than 0.5 percent and NP
values less than 30 ppt CaCO3 for individual strata were considered to be insignificant producers
of acidity or alkalinity, hence, values which do not exceed these thresholds are assigned a value
of zero for the NP and NNP calculations. Applying significance thresholds, overall (the entire
volume of overburden to be mined) NP and NNP values greater than 10 ppt and 5 ppt CaCO3
produced consistently alkaline water. NP and NNP values less than 1 ppt and -5 ppt CaCO3
produced consistently acidic drainage. Noting decreased sulfate concentrations with increasing
NP, they concluded that the presence of carbonate minerals in amounts as low as 1 to 3 percent
(10 to 30 ppt of NP) inhibit pyrite oxidation. Moreover, maintenance of the alkaline conditions
created by carbonate dissolution is not conducive to bacterial catalysis or ferrous iron oxidation
and greatly limits the activity of dissolved ferric iron, thus interrupting the self-propagating acid
cycle.
Case Study 1 (West Keating Township, Clinton County, Pennsylvania)
Unfortunately, actual mine sites having adequate acid-base accounting data, water quality
monitoring, and records of mining practices (including alkaline addition rates and placement of
materials) are difficult to find. One such site, however, is located in West Keating Township,
Clinton County, Pennsylvania. The area had been previously mined on a rider seam 10 feet
above the main bench of the middle Kittanning (MK) coal, and had not been reclaimed. The
recent operation mined the remaining MK coal and reclaimed the previously mined area. The
total area affected by MK coal removal was 11.5 acre and the maximum highwall height,
including old spoil, was about 20 feet. Overburden analysis was performed on five drill holes,
but only sulfur was determined. The deepest hole was 18 feet to the bottom of the coal and seam
and the shallowest was 5 feet. Rock between the rider coal and the MK was described as "soft
brown shale," indicating weathering. The coal had the highest sulfur of any of the strata
encountered, ranging from 0.28 to 0.50 percent. Sulfur in the rest of the overburden was 0.13
percent or less. No NP was determined, however, based on experience with other sites with
Geochemical Controls
2-51
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ill'U;!1,,", ' \ I,',1 ', "III :,!',:*, IV,
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lir Ejiif^g ti,;.' RShallow^qvfflrburden in the same region, it can be assumed that no significant carbonates were
::; .utfMHi-x tjlllb; 'll1;1!' I
present.
Bl ;.;:) , :;
^"Mining began in January 1988, and the site was backfilled by the end of March 1988. Some
alkaline material was added during mining, but the precise amount is not clear. The operation
permit required 10 tons/acre of limestone to be added to the pit floor, and there would have been
another 5 to 10 tons/acre of limestone added to the reclaimed surface for revegetation purposes.
It is suspected that these alkaline addition amounts are minimums, and the actual amount added
was probably several times greater.
A downgradient discharge from an unreclaimed pit (Kl) was monitored before and after mining.
Following mining, the location of the discharge moved down hill to a lower seam that also had
been mined. It is unclear why this point was not monitored during mining, although it may have
11111 I . I IllJ 111 III I II II II (I I I II I I I I I III I I I 111 INI III III I 111 II II II II
gone dry. Figure 2.2.3a shows water quality over time for net alkalinity and sulfate. Water
quality improved following mining. Because the overburden contained virtually no source of
alkalinity, the increase hi alkalinity would not have been possible without the importation of
limestone. The added material was adequate to maintain net alkaline conditions from 1990
through sometime in 1994. The sulfate concentrations, mostly less than 40 mg/L, confirm that
there was little pyrite available for oxidation. These concentrations are typical of premining
sulfate within the Appalachian Plateau (Brady and others, 1996). Comparatively small amounts
(perhaps around 40 tons/acre) of alkaline addition may have been sufficient because of the small
amount arid highly weathered nature of overburden present at this site.
it
'
P'J. ';' f.'Mr ^'llli i:l:l!iilii i f ' i
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2-52
Geochemical Controls
in i i in i n n i i nil n inn
in n i in in i in in in n i iiiiiini 1111 n i in in 111 n i i in niii|ii| nil i HI n 111 linn ill
-------
Coal Remining BMP Guidance Manual
Figure 2.2.3a: Water Quality Before and After Mining at the Keating #2 Site, Clinton,
PA
60
-s 40
ฃ 30 -
.jj 20 -
I
< 1C
*>
0>
Mine Discharge K1, Keating #2 Site
0 - - -I
1986 1988 1990 1992
YEARS
1994
1996
The Case Study 1 site illustrates that a surface mine with weathered overburden that lacks pyrite
can produce alkaline drainage with a minimal quantity of alkaline material added as a safety
factor. Without the addition of alkaline material, there would have been little or no alkalinity
produced.
Geochemical Controls
2-53
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Coal Remitting BMP Guidance Manual
Case Study 2 (Boggs Township, Clearfield County, PA)
nil i11
This study" site is just to the south of the PA(19) site (Appendix A, EPA Remining Database,
1999). The alkaline addition measures used on PA(19) were partly derived from experience
I :
gained from this site. Rose and others (1995) reported results from an ongoing alkaline addition
demonstration project in Clearfield County, Pennsylvania that indicated positive but preliminary
results. More recent data from monitoring wells in the backfill show mixed results. Baghouse
limes a lime production waste product, was applied at rates ranging from 150 to 1,080 tons/acre,
i
adjusted to 100 percent CaCO3 content, based on ABA calculations using significance thresholds
and correcting for deficiencies in NP. Areas with the highest alkaline addition rate (and the most
1 in || | || in | in | || 111 in | || 1111 mi in I I I II II I I1 '".nil Jlinlj HP ซ"! *! !!iiii"t|lni|i,",i!!:ii:i ''MlllllllliiililliiHI ' hm,1,,,!!!1,* ,'il'li'1" I [ ii I"1,; "'Vil' !", ". i|!4i!l!i V. 'j 'ii ,,<:I|P 'V'Ijiil 11 l!" IOIIIII
acidic overburden) were successful in producing alkaline drainage with low concentrations of
dissolved iron and manganese (Figure 2.2.3b). Backfill wells in areas which received lower
alkaline addition rates showed both alkaline and acidic water and relatively high levels of
I::::" .', :;I: ','' '...'. ".;"-'..?^-1';.:/: .'-: I ''.: ::-- . ::,!:, ; .".>. .-. :'
dissolved iron and manganese. Post-reclamation sulfate levels of 300 to 800 ppt in all of the
monitoring wells indicate that AMD is being produced but neutralized.
Figure 2.2.
1000,00 -
100,00 :
CO
5 10,00
g :
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3b:
Water Quality Before and After Mining at the Cast
Backfill Well Manganese Concentrations
o BF2 Mang
~A BF3 Mang
1993
'
; A^'
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1994 1995 1996
i, ,'", , '";,, ,";;'': ", '. ' Period of Sampling
1997 1998
2-54
Geochemical Controls
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Coal Remining BMP Guidance Manual
Based on the experience from this demonstration project, it is probably unrealistic to adjust
alkaline addition rates based on minor overburden quality variations between drill holes. Unless
there is a corresponding change in stratigraphy, alkaline addition rates should reflect aggregate
(average) overburden quality.
Evans and Rose (1995) also reported the results of alkaline addition to large test cells constructed
solely of high-sulfur overburden from this site. Cells were constructed of 2 percent pyritic sulfur
mixed with different amounts of alkaline material. Although alkaline addition reduced the
generation of acidity by as much as 96 percent, even the highest alkaline addition amount,
equivalent to 3.4 percent CaCO3, was insufficient to prevent AMD formation. Two important
considerations resulted from this study. First, the high-sulfur overburden was exposed to
weathering for a considerable time period before cell construction and application of alkaline
material. Test cells remained exposed without a soil cover for an extended time period
thereafter. More rapid application of alkaline material and timely covering may have reduced the
likelihood of AMD formation. In other words, once AMD generation starts, it is much more
difficult to slow its formation than to keep it controlled in the first place. Second, because
complete mixing of alkaline material may be difficult or impossible to achieve,,
microenvironments within the spoil can still allow acid production and bacterial activity. AMD
formation in very high-sulfur mine sites or areas of concentrated high-sulfur refuse, represented
by the concentration of highly pyritic material in the cells, may be impossible to ameliorate using
alkaline addition rates which have otherwise been successful in mines with more typical sulfur
values.
Case Study 3 (Appendix A, EPA Remining Database, 1999 (PA (8))
Smith and Dodge (1995) reported on an alkaline addition site in Lycoming County, PA, which
was part of the original Brady and others (1990) study. Alkaline addition rates of 600 tons/acre
and daylighting of an underground mine resulted in dramatic improvements in water quality from
the underground mine discharge (Figure 2.3.3c). Pre-mining net acidity values exceeded 100
mg/L. After remining, the discharge was predominately alkaline. Increased sulfate
Geochemical Controls
2-55
-------
ill Jin1' liiinii iinii iii'i'iiiiiiiiiiipriiflfiBi' ',: i:i!iiiiiiiiiiiiซiซiiiiiซiปii min i ininllT t; iiiiiiiiii I'/nr IIF n ,11111 i" ir 11 s"" n,n ;, t - \ i : i IT :iiii i*,:' ts,,,' n i : us ! '"': t"':::'!,:", r :' ? fii i1" sic ii, mf >i i1 f H iiiiiiiiiw11' r' "i:
if,,.ilWireJIIil Mil' IflWPlillS" I'll'' li fl'ilif*!!!!!' : ''ili'l'iil'illliliiillilllltllllllllli'l'ifllllllllilll'IIP i' Illllliliplpii"!'!!"'!'!!'!''''i?!! I
,', I, Si1. , ,!!>,:,' H |i,' ,ฅ'',,'; :! 'n,!, I'l, ""'IB1 T it I"
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iiiii CoalReminlngBMP_Gui^nceMcauiai
cbncgnlfatipnsindicated that the improvement in water quality could be attributed to
||' If],!';'"' fI'f 1,';";. ^.^IStijfi^^^pi^, py imported alkaline material rather than daylighting. No naturally occurring
: Iii'"!'" iii ' l!''''i ' ill tit.' '1 W'-:!ป 'iiiii ii'iiiT":f < i ! ii .*'' SI"! li II ii!;:"" i,": M": I,' i,1!'"* Iv > ,:ป>'tt';'' I! ill: mW - ffiife.i'li'W.flM'' ill1'': 1ป'. ' '*, Si. 1 IftfiiW Jill i' ' $1
i oldest successful alkaline addition
I i:1':'"i"" ;.lplfi''f iiit^ Iii ''!"i i. I if Jriiiii"'" I-1',1:' i"'1'""; ' IB$HK. If is"1' Ki
11 Pis*' i ,,,( ' ' i ' fit. '' M,-ait' ',11 ii'iii'l1 "if < lit i ii .*- fiifilifl i, i i:''' 1" iiM"'ซ;' i 'i':,!"ซ; IV > ,',i.iii'!'':ir{'ii".v"'' V f: :ซ. :ป('' - H$r/s
f l','l"f" fit i- E'&l.kง!Jine material, was present. This operation is one of the oldest;
M' = P in,"' ., 1!" "li1 i' "'lil '"''ii "'''11 '$ ! t"" 1 ! *! '" ''H'h 5 '"'!"''"'' ^!i > i i A*?f i "iiii'' [ i, ' : ';, | ^ i^l ;|ji| i| ill
Wl llj l! i"! ^JttfrftR- If n^s ftvhihit-prl imnrnvpH ix/af^.r nnalitv cirปr^ th^ rmcp-t r*f 1^
ipj, " ^',; ;, *! HI,, i w, ". iiซiiiiiปnipii,iiii ", .iiniiiijiipinii iiiii,1!' "i1,,"11 ', "Hi" "r ,,, , ,1'" ,i '" ' ;; i'i:,,|, ; < pi : ป ,, i a,,^; ;, u .tinp ><,, ,a\tif"tf n., , i IP'!!ซป: ';;;; mill Tif iii',iiiii r, ,> jini1,1:!!, iiiiPniiiiiULiiP1: iiiimiMin",,!!,!!1 'liiiiiiiiih'iihi,'!1:1 , , / iiisip1 ,'i.pp'ipii'ip,r,iii:ii,ii|iiiiiiiiii!P!ii',,'iiปiiip: ppm : niiiii
sites. It has exhibited improved water quality since the onset of large-scale alkaline addition in
if ."i '; i 'ii.i.'. , ' -": Ii iii" tiiifii;"; i'i'iiitii, '^mi". * iiiii i ILL ii:.!,," & m^ i ;* 'fi';::", itiiiii, ?f,,," J ii i * zii i- ">f *;: S'"': m\iฃ,^ iiii;iปi;^ r'7"ป"*i : if mjf> ,ii jif'"': jfts.:", i is! "iii:i .:;is i-'i .iiii ^:'?i:. 'iii I
l^^t,:,^ !' >'l'i;||Jl^,0ran^ pjoducedjpredominately alkaline water since 1989, suggesting that the impact of
alkaline addition will be long-term or permanent.
;'| "^ ^ ''' '^ ^Kgure 2.2.3c: Water Quality at the Case Study 3 Site
Backfill Well Net Alkalinity Concentrations
ll,i'i|i''iii''ililT I"' II",IIli'li'
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-------
Coal Remining BMP Guidance Manual
Figure 2.2.3c: Water Quality at the Case Study 3 Site (continued)
Backfill Well Manganese Concentrations
^ 100.00 : -
== 10.00
Mang
1 995 1 996
Period of Sampling
Backfill Well Sulfate Concentrations
I
te Concentrations (
j. i
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1993 1994 1995 1996 1997 1998
Period of Sampling
Geochemical Controls
2-57
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Coal Rernining BMP Guidance Manual
Figure 2.2.3c: Water Quality at the Case Study 3 Site (continued)
i!iซj%>. ป,, ,,i'! til i;'1?
li,i,;-I L
Backfill Well Iron Concentrations
100.00
ซ moo
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Case Study 4 (Sequatchie County, Tennessee)
i MI iiiiiiin iii i in i i ii i i MI
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Most of the published research in alkaline addition has taken place in northern Appalachian
states. An exception is the work done by Wiram and Naumann (1996) on an AMD-producing
surface mine in Sequatchie County, Tennessee. This site is adjacent to the TN(4) site (Appendix
A, EPA Eejrjinipg Database, 1999) and the pollution prevention measures used on TN(4) were
first applied at this study site. Alkaline addition was implemented as the principal component of
a toxic materials handling plan that also included selective overburden placement and the
^_^_-__,_ of chimney drains and alkaline recharge basins. Alkaline addition rates were
BIB, ... i,i:;U ,.:l ,''!|."i|;!, , lEIIBBliB iillllil "Til";1!,!:; .,;,..'',..!li, <;, ,,i, I;,!! ".mil i'.'l. Illi rP'-in: 'I.':, "ills- ,!,"' * HI'll'l.,, i I||M .' "iiปn,, |. iii! 'ni'!'!!'i|! '.,:'"' W 1!',', iltii "i -iilEKjIBliii,!,::, .iiP.PH '.I'lHI!. p I Ml"!1,,, |J;II,IMป: : : 'Ji'11*!1,:1'1,1'!: ,"' ป '::' ,, , :, 1 !< 4 i
determined for individual stratigraphic intervals having a NNP less than -5, however, a modified
NP test was used in order to exclude the apparent NP contribution from siderite (FeCO3).
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2-5S
Geo'chemical Controls
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-------
Coal Remining BMP Guidance Manual
Previous overburden analysis results erroneously predicted alkaline drainage due to the presence
of siderite that falsely indicated the presence of significant alkaline strata. The role that siderite
plays in mine drainage and acid-base accounting are explained by Skousen (1997). Limestone
application rates for these intervals were summed to determine the application rate for the area
around each bore hole. Net neutral zones were not factored into the calculations. Results of the
Wiram and Naumann study were favorable. Monitoring wells on the site in the backfill spoil
area that had alkaline addition have higher alkalinities than wells into areas that did not have
alkaline addition.
2.2.4 Discussion
It has long been known that mines with sufficient naturally occurring calcareous strata produce
alkaline mine drainage. It is a logical next step that sites without sufficient naturally occurring
alkaline strata can be made to produce alkalinity by importing the appropriate amount of alkaline
material. The questions are: how much alkaline material should be added, and where should it be
placed? Another question that can be of equal importance, especially in sensitive watersheds, is
how much risk of failure can be tolerated. The literature and the case studies cited above provide
some insights into these questions and identify benefits and limitations of the methods.
Benefits
Alkaline materials are an effective means of neutralizing and preventing acid mine
drainage.
Alkaline materials are generally readily available, and in some cases available as waste
products that would otherwise be landfilled.
Alkaline addition is probably the best understood "chemical" BMP, and there are natural
analogues (i.e., calcareous mines) for comparison.
The amount of material required to assure alkaline drainage for low to moderate sulfur
sites is well understood.
Geochemical Controls
2-59
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I II II II I
Coal Remfning BMP Guidance Manual
f
The chemistry of the alkalinity generating processes of carbonate minerals is well
Widerstood.
Site:specific data can be obtained to determine the amount of alkaline material that needs
to be added.
wrif
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ป Alkaline addition is not generally effective at fixing a problem once it has been created.
jl*"''"- "K ซ: i J f :| t :*[J(jf :j Jill. | illjit j; I'Wijiii: j-,',,,;; ปป | .t, i.; - ,. ^. . ;:: || || JtJiK^;!! '|,f|y . v^ :i|j|i [ fi 'j^. ;; ;}'- r -ff iT.;::,, j' ",! j,f |:iS|S|:}i
il,.',,,. :, Jjfcalinity from carbonate dissolution is limited and may not be adequate for high sulfur
;; mines and coal refuse materials.
Alkaline materials can armor with iron precipitates and become ineffective. Proper
in1 i' - "3'i'ii,;: li'lhXf'UH^ " jiti!"9'!! '"iLi'V'S1 S> '":', liiiuiiiiiii !K"i'>:ii!i i:;; i,r in,: jiiii :< .n/f'1' ,'ii" i,: f 'WIL./^ n r , ,.. < , u .,< , >.< pn '.ป < -ป -F
placement of alkaline materials to avoid high iron water is a way to prevent this problem.
? Ensuiing that a site produces alkaline water does not guarantee that effluent limitations for
iiiii;': ,..'"; i:is; ; 'Or,', i, iii, .ifr L i iii: . /"; :i,i,:, > > '":' ; i .,; I <: .j '::..: ;i' ซ 4 '.; ii (f ?, 'sjrif'fi; .:; 'si ii ii>wi";.; it ' "' f ii1. ': ' i: -K i -iik ii!ซ: w
I'li, i;!;: (,metals will.be met, ( |ip , i{ U|
bf. Sideril? cmproduce overburden analyses that falsely predict alkaline drainage. A
111!!'1' ft!, ii'ii Jin*: 111 !l, WM"' 'I; !f:'i;;i'ป i 'I! WJ mt';"ฎ'^ i 18 ii, '%, HM 'J&k^l ''t l':^' ' 'I , WiZi Jii
ii":-"ซl
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q|| fpr ^ejgr^natiqn,,of neu|rali2ja|i:pj potential can greatly reduce this risk.
.
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Efficiency
Alkalme addition has proven to be an effective mine drainage prevention technique for
mines with low to moderate sulfur content.
? Studies show that mines with net neutralization potentials greater than 12 produce alkaline
1L T".;,-.,'d*8*113!?6-
* For sites with moderate sulfur, alkaline addition rates below 500 tons/acre typically have
not produced alkaline drainage.
Alkaline addition rates at less than 500 tons/acre can be effective for low sulfur sites that
Would not otherwise produce alkaline water because of a lack of naturally occurring
'Kv:;,-,;:.carbonates.
S More work needs to occur in the southern Appalachians to determine appropriate addition
rates for those geologic conditions.
'. ;,.;:!(I
: !",:!ป! '."'Jill , i; ' ! " '
2-60
,,,, , Gepchsmical Controls
Ill i H n i
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Coal Remining BMP Guidance Manual
2.2.5 Summary
The addition of alkaline material to surface mine backfill can be an effective method of
compensating for overburden that is naturally deficient in neutralizers and thus, reduce the
potential for acid mine drainage. Two categories of alkaline additives currently are being used
on Appalachian mine sites, limestone (and its derivatives) and coal ash. Coal ash addition was
proposed for 8 of the 17 alkaline addition sites in the BMP-site data packages.
To successfully prevent the formation of acid mine drainage, a sufficient quantity of alkaline
material should be added to the backfill. Most successful alkaline addition sites to date have
used substantial application rates, exceeding 500 ton/acre. Lower rates have proven to be
effective only for low-cover overburden with very low sulfur content. Alkaline material is best
applied by distributing and thoroughly mixing it throughout the backfill. It also may be useful to
place up to 100 ton/acre on the pit floor. Surficial applications of alkaline material are less
effective due to low solubility of calcite and limited contact with acid-producing materials deeper
in the backfill. Most failed alkaline addition sites either had used application rates that were too
low or employed ineffective placement of the alkaline material.
Geochemical Controls
2-61
-------
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Coal R&mining BMP Guidance Manual
111 III II 111 II (11
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2-62
Geochemical Controls
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Coal Reminins BMP Guidance Manual
2.3 Induced Alkaline Recharge
Constructed recharge infiltration pathways composed of limestone within mine backfill have
been used to increase alkalinity in mine spoil and to increase oxygen availability within spoil.
These pathways can be near surface features (trenches) or deeper structures that extend from the
surface to the base of the spoil (funnels). Surface runoff is directed into these pathways where it
contacts the limestone and generates alkalinity. The pathway is positioned such that infiltrating
water would not contact potentially acid-generating rock. As originally envisioned, the goal is
net alkaline water in the mine spoil. A second goal at some sites is to induce oxygen into the
backfill with the purpose of precipitating iron from solution. The principal studies on this
subject have been conducted by Caraccio and Geidel (1984, 1985, 1989 and 1996) and Wiram
and Naumann (1996).
Theory
Pyrite oxidation can result in significant quantities of soluble, acid-producing oxidation products.
In fact, mine drainage acidities in the hundreds or even thousands of milligrams per liter are not
uncommon. Calcite dissolution on the other hand is much more limited in terms of alkalinity
generation. At surface conditions the maximum alkalinity is less than 100 mg/L. Carbonates are
more soluble at elevated partial pressures of carbon dioxide and under high Pco2 they can
produce alkalinity as high as 500 mg/L, a condition that can occur in mine spoil. Alkalinity and
acidity are both reported in the same units of calcium carbonate equivalent and, for example, 100
mg/L of alkalinity will neutralize the acid from 100 mg/L of acidity. A good discussion on the
chemistry of pyrite oxidation and carbonate dissolution at coal mines is in Rose and Cravotta
(1998).
It has been proposed that one way to offset the frequently unequal generation of acidity in
comparison to alkalinity was to increase the load of alkalinity. Load is concentration times flow
Geochemical Controls
2-63
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Coal Remining Bfijp Guidance Manual
and is reported in units of mass per time period (e.g., pounds per day). The means proposed to
do this was to divert surface runoff into trenches and/or funnels filled with limestone. This water
would contact and dissolve some of the limestone. Thus the water flowing from these structures
onto the spoil would be alkalinity enriched. It was hoped that the increase in the volume of water,
'' ; ": ';;' fevenwlth JJJjted ^j^inlwrwould''result'm a large'ehougfi'alkafinity Ioac( to offset the spoil
Ililr I ijii |1jj| :!>', i|;||i[ fP1|!:i|WV<'!lBtr" ;M:IJEWiyH:jJr. W'j;.I- * J i j; ':$<& 'S.l*Wi*:n J:'p--r-.:iraS( 3 m\. *.(iiVina*?jy;::,, Wi-jjii
water's acid load. It has been estimated that it would require 3 to 8 times more water in contact
with the calcareous material than the water in contact with the acidic material. This concept was
developed by Caruccio and Geidel (1984) based on laboratory work by Geidel (1979).
A second purpose for recharge pathways is to promote the inflow of oxygen into the spoil.
Oxygen could enter the spoil in three ways, dissolved in the infiltrating water, entrapped in the
infiltrating water, and with air directly entering the recharge structure. This would be used
where waters are already alkaline or only slightly acidic and where the water is iron-rich.
Reduced iron (Fe2*) precipitation is very slow even at neutral pH, however, oxidized iron (Fe3*)
precipitates rapidly under alkaline conditions. The additional oxygen would help to enhance
oxidation and precipitation of iron within the backfill.
2.3.1 Implementation Guidelines
Caruccio'and Geidel (1984) suggest a refinement to the above concept which would incorporate
I!
special handling and capping of acidic material. Acid-producing material is placed in pods and
' ' ; :":' ';i' r ' """ ' ;":; ';"; :i- :'" ~" i::;"'" :;'::::" ':;;;" ;i" ~ ; ' " ;": * - " :"' 'ii:;::t; Lj" ;" " ' ;:i";' '' " : -
capped with clay. Alkaline recharge channels are located such that infiltrating water enters
"neutral" of alkaline spoil located between the pods 'of acidic material This concept is depicted
in Figure 2.3.la. The purpose is to minimize the amount of acidic water and maximize the
amount of alkaline water that reaches the water table in the spoil.
Ill II I III
I"III! i II (1
II III III
2-64
IK
ill
Geochemical Controls
I ill I i in
i ill 1 i i I ill III
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CoalReminingBMP Guidance Manual
Figure 2.3.1a:
Alkaline Recharge Channels and Capped Acid-producing Material
Pods (Caruccio and Geidel, 1984)
>
J^^s^ifrr^^
If recharge trenches are installed for the purpose of inducing oxygen into the backfill the
limestone (or other type of rock) should be of sufficient size and sorting to be easily permeable to
air.
2.3.2 Verification of Success or Failure
The BMP should be constructed as designed and the on-site construction plan should be
documented. Means of documentation include:
Engineer's certification of construction.
Photographs of the structure as it is being constructed.
Locations of the recharge structures accurately located by survey or global
positioning system.
Verification of the amount of imported alkaline material by weigh slips or another
accounting method. Weigh slips would be submitted to the regulatory authority at
specified intervals. A copy should also be available for inspection at the mine site
by the mine inspector.
Geochemical Controls
2-65
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Coal Remining BMP Guidance Manual
Increased inspection frequency may be needed to verify that a BMP is being constructed
as designed. Inspections can include examination of limestone weigh slips and
verification of the size and type of imported material.
iiii i
Photographs of the construction process can be taken by the mine inspector, company
i1
.engineer or other qualified person. Copies would be placed in the state permit file. A
: :;?' i'; ..... ปf': nairrative, including" date and location, should'accompa^' each phbtograph.
': Ii! ' .-iKf' ..... i .......... ii'. 1;!j" % L: ;' i '' Wvl.: ^ i:iS ' ; ' K * " E"? : i B ..... !;P ' 'i
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flualiiy monifbring should include both concentration and flow at discharge points.
This is especially critical for renaming sites where the intent and purpose is to reduce
loads of constituents. Because alkaline recharge structures increase flow into the ground-
water system, being able to determine load is critical.
Monitoring for concentration and flow, as well as other accurate documentation of construction,
111 W II II II11 III I II IIIIIII II I II II I I III I III I I I I 11 II I III III III IN I I I I I I I I
will allow for future improvements in design and determination of the efficiency of alkaline
recharge structures.
in in i in i
2.3.3 Case Studies
The case studies discussed below are examples of sites where the alkaline recharge concept has
been applied.
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-------
Coal Remining BMP Guidance Manual
Figure 2.3.3a:
Topography, Location of Recharge Trenches and Funnels, and
Locations of Seeps (Case Study 1, Upshur County, WV) (Caruccio
and Geidel, 1984).
Fifteen alkaline recharge trenches were installed to divert surface water into the ground water
system in the summer of 1983. The trenches averaged 10 feet wide, 3 feet deep, and 75 to 725
feet long. Trench floors were capped with sodium carbonate briquettes (0.5 Ibs/ft2) and covered
with two feet of limestone reject. Halogen tracers (KI and KBr) were placed at the base of the
trenches to serve as tracers for infiltrating water. Eight months after installation, the tracers
appeared at the seeps. At this time the acidity decreased to a range of 75 to 125 mg/L. Because
the water was still acidic, fine limestone (up to Vz inch) was broadcast over the site at a rate of
100 tons/acre in 1984. The acidity continued to hover at around 100 mg/L.
In February 1994 eight funnels were installed adjacent to or within the trenches. These funnels
were excavations of approximately 4 feet x 7 feet x 8 feet, and were filled with a total of 60 to 80
Geochemical Controls
2-67
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Guidance Manual
, , Coal Retaining
Hi'lii
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tons" of coarse limestone having a CaCO3 equivalent of -70 percent. The purpose of the funnels
was to transmit water directly from the surface to the water table. Following funnel installation
I;
acidity was 50 to 100 mg/L.
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Coal Reminine BMP Guidance Manual
Figure 2.3.3b Plot of Acidity versus Time for Seep #2 at Case Study 1 Mine. (Vertical lines
indicate when recharge trenches and funnels were installed.)
Mercer Site Seep #2
600
500
400
300
200
100
Acidity (mg/l as CaCO3)
1981 1982 1983'1984 1985 'l986 ' 1987 ' 1988 'l989 r'l990 :1991 !1992 ' 1993 994 ' 1995
-100 4-.
There are four possible interpretations of the observed decrease in acidity concentration:
1. Trenches and funnels provided alkalinity to the ground water and thereby
neutralized existing acidity.
2. The trenches and funnels increased rain water infiltration into the ground water
system, thus diluting the ground water and lowering concentration.
3. Some natural attenuation occurred through time. A control area with similar
overburden would have to be monitored to account for the effects of this factor.
Geochemical Controls
2-69
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4. The decrease in acidity concentration is the result of two or three of the above factors.
i
If the decreased concentrations are due simply to dilution, increased infiltration could result in an
increased acid load and exacerbate the problem. For example if:
Before construction of funnels:
Average flow is 10 gpm and concentration is 250 mg/L.
10 gpm x 250 mg/L x 0.012 = 30 Ibs/day acidity
After construction of runnels:
'"Average flow is 30 gpm and concentration is 150 mg/L,
I,:" ,i' "! :i;,jll t1 iSi illliii:!'! i iiiiiiiiiiiii -Hull r ' Jiitii, r: uiiiiii.1 EIIIII*' ,:i :!';,' i>in|il:,'!'!" K Ii i 'lifl, ,lll:ii::,':,"r", 1:111 Ilii'' r' :i,i,"9i :>:' "Tl
30 gpm x 150 mg^ x o012 = 54 Ibs/day acidity
An evaluation of whether this BMP was effective requires a knowledge of both flow and
concentration.
Case Stm
1(1
i hit
:dv 2 (W:
iram and Naumann, 1996; Wiram, 1996).
|
This site is located in Sequatchie County, Tennessee. Mining began in September 1987 and
I!
mining used loaders and trucks. Once the initial box cut was in place a dragline was used. Cast-
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blasting was later employed along with the dragline operation.
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In mid- 1990 pollutional seepage began to enter a receiving stream. The mine discharge water
had pH from 3.4 to 7.5, alkalinity from 0 to 121 mg/L, iron from 4.8 to 48.6 mg/L, manganese
from_2.3 to 34 mg/L, and sulfate from 8 to 812 mg/L. The coal company embarked on an
llllllil |, ,,1'f1'! .ill"*1 fijiirt11 iMiI'llilllllllH^^^^ Iililllllilli'i!' lSilll'i.i,;Xl!*illi!li;,>;li!*'i|lll:ii n '"'..i li'li'li' "''! :,\\ " Si IPr ..... ! I bk'""^^;" ...... ft' , i I'1 i! *"' ' 1 ....... ' , '" li'lhP ,'!' l,:l "HII'.lhilNli"*'!! ' 'ฅ T;|||||||Hป lillliniH|||H >,,'ซ" 11,1, < .''I'.iOi'luilll!.' ' , ปi ' ' '" i ,i j.,1:".
determine the source of the problem and effective methods for
' illll'lil'lllll!!'"!' ' iilEiJ;1 ' "Ullll I
resolving the problem. Alkaline recharge structures were just one of several BMPs that were
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used. Other BMPs included special handling of overburden and alkaline addition in
iniiiiiiiiiiniiiiliiiliri liiiHi hiniiii'1 j.'iii ;ซ ''r';"," i .'
-------
Coal Reminins BMP Guidance Manual
The alkaline recharge structures were approximately 150 x 50 feet, with a depth of 12 feet, and
were often placed over chimney drains which had been constructed in the backfill. The recharge
structures were filled with four feet of "crusher-run" limestone (0 to 1.25 inches) overlain by four
feet of limestone gravel (2 to 2.25 inches). The remaining four feet was for "free storage." The
purpose of these recharge drains was different from that of Case Study 1. In this case, the drains
were installed to enhance "the alkaline/oxygen loading" of the backfill ground water. The key
objective was to induce metal precipitation within the backfill.
This site can be divided into two areas in terms of BMPs. Most of the site (the southern seven-
eighths) was mined conventionally without incorporation of special BMPs to prevent water
quality problems. The northern one-fifth was mined using special handling and alkaline addition.
Both areas had alkaline recharge structures installed. A map of the site showing the location of
alkaline recharge structures, monitoring wells and the area where alkaline addition and special
handling were part of the mining plan are shown in Figure 2.3.3c. Monitoring wells OW-2, OW-
5, and OW-8 were placed downgradient from recharge trenches. Table 2.3.3a shows the range of
water quality in terms of pH, alkalinity, iron and manganese for these wells, as well as water
quality for wells OW-7 and OW-10.
Geochemical Controls
2-71
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Coal Remitting BMP Guidance Manual
Figure 2.3.3c: Map of Case Study 2 Site
Legend
Alkaline recharge structure
ov;-5 Monitoring Well
Area of special handling
and alkaline addition
Permit boundary
III I
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-------
Coal Remining BMP Guidance Manual
Table 2.3.3a: Water Quality for Wells at the Case Study 2 Site (data interpreted from
graphs by Wiram, 1996)
Well
Date
PH
Alk.
mg/L
Fe
mg/L
Mn
mg/L
OW-2
10/90 to
4/93
6.0
100-175
15-30
10-20
1995
6.0
125-
150
<1-15
8-18
OW-5
7/92 to
4/93
6.0
-100
<10
-10
1995
6.0
150-
200
10-20
-10
OW-7
7/92 to
4/93
6.5
-450
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Coal Remitting BMP Guidance Manual
Case Study 3 (Appendix A, EPA Remining Database, 1999, TN(4))
II II | |n n n ill ill IIIII III II I "" i1 , ปu: I'll" f 1 II I I I II I I
This site was submitted as one of the 61 state data packages. It is located in Sequatchie County,
Tennessee and is immediately to the east of the Case Study 2 site. The same company is mining
both sites and experience gained at the Case Study 2 site was incorporated at the Case Study 3
site. This site incorporated numerous BMPs in addition to alkaline recharge structures, including
"::;"" ;~*!,; ZT,'~~ '':': \i.' :r' i1,1!'..":'.."".'".":: ; , "~rr,r,",:. v.,".'':"":" .' ri'.i",: : _. I".", ."' ":;f: :"'~~ :,v,""I.'.' '.'..'. ""i ~'. ~ "...".
alkaline addition, special handling, compaction of spoil, backfill hydrology routing, backfill
water inundation, and stream buffer zone expansions. Only the induced alkaline recharge
structures will be discussed here. The surface feature is a depression that is about 150 feet long
by 75 feet wide and 12 feet deep. The area filled with limestone is somewhat smaller and the
depth of limestone is about 8 feet. As with the Case Study 2 site one of the goals is to promote
lie flow oFbxygen into the spoil for in situ precipitation of metals. The effectiveness of the
*h::;' "'|>*. ': f';' ^measures used at^t&is site can not be evaluated because tiie site is still active. ^ _ ^^ ^
iiliii tiesl'.'v j iiili!!' JDJl1 1 ป" "iit/rti.!" tvmif iiป\ (! ''ป,', ' ;. :;'.!J 'i .Mil "'"I!::11!/ '" ;,i'-hii,;1'! ,( .' '''t'i'i ! '*"i. ^iji ^""li .:iซป:ป!*l!ic'K'i!l ''' ::*,'., '&''!,'. 'n ' . "', !( .! ::" i'''lililii UK, -Si:S I
i
2.3.4 Discussion
The theory of increasing alkaline load by increasing the amount of water that is- in contact with
calcareous materials is a valid concept, although it is not without potentia
II
problems and is not
applicable to all mine sites. The benefits and limitations of implementation of this BMP are
highlighted below. Most of the potential problems have not been discussed in previous literature.
Benefits
Surface water is preferentially directed to calcareous material that can produce alkalinity.
The water will flow through the limestone in the recharge structure and avoid contact
With acidic material.
! In,.,nil ''"' JliiUIR1'!1
Water flowing into the structures will be surface runoff (i.e., essentially rainwater) that is
low in dissolved solids, and more importantly, has low metals concentration. Water
containing high concentrations of metals, such as mine drainage, can coat (armor)
limestone and other calcareous materials rendering them ineffective.
2-74
1 iS!!; ''Si /!!;::
iil1. Hi " inillli: , ..'Hi
Ti'ilnlL'U!11 fllllfllillH IV
GeocJiemicat Controls
:,:ซ!: il," 4'!l-. ., ':
,, j!,r i'ii:!iii:n|iiiiiiiiiiiB .iii' n ,p yji
-------
Coal Remining BMP Guidance Manual
Limestone recharge structures are passive and require little, if any, maintenance.
Recharge structures can introduce oxygen into the backfill to facilitate oxidation and, if
the water is sufficiently alkaline, metals will precipitate in the backfill rather than at a
surface water discharge point.
Limitations
Limestone only dissolves when in contact with water, thus only during precipitation
events is the limestone in contact with water.
Permeable trenches can increase the flow of air into and out of spoil. This could increase
oxygen availability and decrease carbon dioxide within the spoil. Increases in oxygen
can be desirable (as in Case Studies 2 and 3 where the goal was/is to precipitate iron in
the backfill), or undesirable (if the spoil is highly pyritic). Retention of carbon dioxide
(CO2) in spoil can be important if calcareous minerals are present because carbonates are
more soluble when CO2 is elevated, a condition that often exists in surface coal mines
(for examples of mine sites where elevated CO2 has been measured see Guo and Cravotta,
1996, Lusardi and Erickson, 1985, and Jaynes and others, 1983). This is-the reason that
many mine waters have alkalinities greater than 200 mg/L (for examples, see Hornberger
and Brady, 1998; and Brady and others, 1998, Table 8.2).
The increased flow into spoil could potentially increase load of undesirable constituents
such as acidity, metals and sulfate, especially if the water entering the spoil flushes
oxidation products that have built up between precipitation events.
To reach saturation with respect to alkalinity, water should be in contact with calcareous
minerals for a sufficient length of time. If contact time is not enough, sufficient alkalinity
may not be generated.
Geochemical Controls
2-75
-------
i^lRKr
Jill 'ซ: Illlllllllil ! PI i!!'3;ป,ป'': "
11 '"li'lt ซ' .l'1"'! i'n,,,dill
;",!'1 ":i|i!!!,|i|iii,'i,,i!"?:1!'1", 'i'Siii!:"1'1 'V, ,',:ป 'i,;; ,,|, i
ii
,. ,, ^CoglRgmining BMP Guidance Manual
i, liiiilii ........ ' f. PI! '" i,v ' MIT'rfWi ~t; illiiEiii1 ....... '" , ,!!!', ...... 1
.^P..^ ground water system can result in a
! Hitf .......... i ' Vift' >!'i iiil'Wl JIKI! I , ii! .1 - \.\ '". ! ..... (I'll I'Mli'l :ป"(; Jit ,1! ...... M-.' ; t!i ......... Ill' ' " '! ! " i'> ..... ISlll/L"" HH.I-1' : ..... RllllB. Ill ..... , ,f: It id '! n,i: 1:) '< ..... ,1 -(Jill"1!1,: !' i ". I < "Mini
ing water table. This could adversely affect water quality if pyrite oxidation
HIIIiji ^Tin ......................................... ............. , .................. ...................... ........... ................. r .................. ........................... ........................ ,-": .......... flf ........ A ,y .....................
i
products, which can build up between flushing cycles, are flushed during this fluctuation.
ill11, ,11,.,\,'" -iviiliinlliliililiiliilsriiliiilllilllilllllllliililllllllllll!11;1,,, iliIlilllB ni III,1',!1 liiliii,:"111111:1!:*,,,,!:!!!1!!.!1' >,; ly 'i ,,: '"'i'1 ii'i,,! I ' ,i'',i"iut contained a single well in an area that was not affected by the BMPs. This control well has
higher metal concentrations than wells below the recharge trenches. The recharge structures may
iiiu (""iirii1 '.:lii;,, "i'n i
liliiifl i'
have been effective at in-situ metal removal. Water in all the wells in Case Study 2 was alkaline.
Ah evaluation of the effectiveness of alkaline recharge structures at the Case Study 3 site cannot
:" at thistime "because the "site' is" still active!"
"Illliili: uiii'Mif i"!i! : iife' , '1
I'M,;!;1.! ,, '? itii't ('''' '.-jiii ii'1*! F.pu11 'ivi'. V1*".!**('' & (i,'1'!1'1':! :."'i ::' "?!,
W'tflKl'i'll1: IS"" iiVir 1(1
IK iii:':, r1 in:1 ji/iiiiii1!1 riiii,1;,!'!:;:*!, ' .is: ,Vi>
" [Efficiency '
Hft'^HtfHWVi: 'iMBIi, ''HH.iMf Ui;iJMU3iEi,i"!'lB'iiisZ .'' 'i;,., : Si1'"!,'1!"1, i1"1:1'!1 , '(ซ:. SM i^t.ii "iIฃ'!3S'!i7:K!if/!!" t.jfciT&'jr.'tnvi.i.il ' li:ji I:1! :".. ' i *'"i:.'
Tpntil e|fic|gncy can be further demonstrated, it would be prudent to restrict the use of alkaline
I1",!!!?1?""'!
"iii i'litJ!1!1!!:
m 'a
i
,*" ..... 'I ....... If '!ซ' " " 'Ij.v1" ,"!'i Jป ''I,.'..'1
' '"1 " ' '"
! iilliP'li1',!
' '
rec
structures as a
ifjul,,,'1!!!1!!; /lUiililiillCI ....... f ill I'l,1"'!'11!11! '"'
""I" iliJV ullii ..... 'rilEiiiiiiriil!1'1 Jnll , '"!4 , HI, if,, F'f , ซ , , .' ,, n,, . ,,
to the following scenarios:
," Ulilf'1 '^'Ulllil'll!! ...... ' i ,,'1, ."I'lilNl/'H1, ! ' , "''Lli' "I'i'A1",]
1 " " ..... ' '1
illilil M'jr'#i"
ii|j!i*!|. BV.Kl
liiiiiiliiiii1 i .iiiiiliilF'ii1" , iiiiii11!,.
iWM'Wi :">,ป*'
lllll'llhi'.Jlll III1'! 'i I ih 1111:
III1!
lil! I!1
iiiS.
lllli' ;
Sites:.where&epyerburden contains .very little acid-producing material and there is a lack
; *'!;! **|!tfci Jl'fl^^" J1 iiiiilli1 '; "ii! }'i i".1 iiiiB iiiiiii!'!1"1 -if ii iiliil! 1'jj'i1ซ' i' iirl Ilil1iiiill!l|tl!i ,'iii.f:: i < f ii ' i,1 . :ii " ;lt, iiiiJaiHiiiSi1 '' "utsf "t, nvtK- .iniiit1 isiHriri1' i, ir. .*!'. f 'nhiirti tf i "l in :,i ' -\v-! w.
rocjks. In other words, this BMP should be implemented on "marginal"
lUii'ili" 'K'I'iP "Illlllllllllil'I'i AvnTIINniKi'' i1!1' ml ' iki,!" 'n,:1,,"
Ifi,ill1 ' ,|i"ป Sili"1 SlliJi I'lll.!!!!!"!..:!!!!1 SIS IKS
UiliiJI'Tllll' llti'lliiiri" III" I!1, i "I1 .'!', 'I
11 "IlilllKV, ui'iiiliuiiiiiilli \llllllli1 ill i;1''j
"!, , ,ln ' , 'I lil^'WI'l'lill,,
Sites that would not create severe acid mine drainage in the absence of alkaline recharge
:i!|!5
J ;Js^cloires, But likewise would not produce alkaline drainage. In cases where this
ni ii4n"ii!!iiiiri!iiiiM^ r iiijiiiiiiii ,,': IT if iiiiii1 /.HM 11: 111111111, y mi 1,1,1 u, ,m i,m,i 'im, ,,: unr r,,|,, i lum; i" jiiiiiiii, "ur1;,,,,!, t hl, ,11" .iinm'iriiiiiiii n m:,',,) mi,, "H n,:, r11!1:,,, ,,iir":ii,"iin ;,';,:, iiii ,i,, ,: ;,ini , , iriij, iiihiin, 1,11 i,,,,!1
,, ,
l, i'Vuiiilll"1'1!,,'" iiiillLi,1!'):.,:1,11 ,,|].I:T T: "ft 'Mlili'liil; IT1 llJllliiillKI,1 !"i- Hi'1;!, ,
"i'BL I1!,i:,,:!*,'ill1''ill- ifi
is implemented and where selective handling of acidic materials has occurred,
"^ the'acid! material should be placed above the highest water table anticipated to occur
i ,",!!' "I! flllH,' i lliilHilll nif iH"!!!!1!' , , Tlj ',r ,','" I*! T""!!!! ' ,-, i"n',,,, i i,,i , T, ป ,nS,.,' ,iซ , , ! , >i, i ,ป ซ, n ป!ป |fl, "Fi,,,,, , , ,, ป ,, ,, ,:..
1 >j{$-':: pi;; MIII ":i if11 >,s ;i,rป'hฃ;'t'':, v, ',: *'ii/1,! ,,T-' :":', iiiiii,-."!>?> "M"3iiifii1 ,,i' i f m KM;;,;' ;ff,; iซ.;t i i"!.-:,;;ซ "s'."; IB:,ซ!;;,
iixirgg a recharge event. Otherwise the acidic material may be in a zone of water table
fluctuation.
This BMP has potential use at sites with alkaline or near-alkaline ground water with
elevated metals. The purpose at these sites is to enhance the amount of oxygen that will
reach the ground water and this in turn will promote in-situ precipitation of metals.
i i
ii i iiiiii
2-76
Geochemical Controls
-------
Coal Remitting BMP Guidance Manual
2.3.5 Summary
Although alkaline recharge structures have the potential to induce alkalinity in mine spoil,
experience is limited and there are possible drawbacks that have not been evaluated, such as the
potential for increasing the load of undesirable chemical constituents. The Case Study 1 site had
several acid seeps which had resulted from mining. Following installation of recharge trenches
and funnels there were decreases in acidity concentration. Flow data, however, was not available
so it can not be determined whether acidity load decreased. The mine spoil monitoring wells at
the Case Study 2 site lack pre-installation data. A single control well in an area where BMPs
were not applied is of poorer quality than wells in areas with induced alkaline recharge trenches.
At this site, the primary problem was the discharge of metals offsite. The recharge trenches were
constructed with the intent of causing precipitation of metals in the backfill by increasing
alkalinity and oxygen availability. If a comparison between the control well and the other wells
is valid, this could indicate that the efforts at the Case Study 2 site did result in better water
quality. The Case Study 3 mine incorporated most of the measures adopted at the adjacent Case
Study 2 site including using the recharge structures to enhance the flow of oxygen into the
backfill. The Case Study 3 mine is still active and it is too early to evaluate effectiveness.
The number of sites where alkaline recharge structures have been constructed as a BMP are few
and many questions remain as to their effectiveness. Some implementation considerations can be
suggested, the most important being that it should be certain that an increase in surface
infiltration will not also result in an increase in acid load. The methodology will probably be
most effective on sites with minimal amounts of pyrite and a lack of naturally occurring
calcareous rocks. Recharge structures may also be effective where the goal is increased oxygen
in the backfill, so as to precipitate metals within the backfill.
Measures should be taken to ensure that plans were carried out as designed, including increased
inspection frequency and engineer certification of on-site design. Monitoring of ground water
discharges should include flow as well as concentration so that load can be determined.
Geochemical Controls
2-77
-------
'CgQlKemining BMP Guidance Manual
\
i"
! Iti '!!' I;!'!,! 'iijlllll'l i
III?"Ill !i I'llll'JI 1 III,'
"i ;:,iiniiiii m ..... i ; ป; 4 \ i ' , t i, ' ini.! i i , i; i :, < fl . i iii. * mm 9 , ..... m \ >, ..... , , ป i: ;;;: ' tn ' v, l|! u "; n : > ., a* ic , n h ; , > ;, : ; "ii1 IT ;
.| III! JliliLiW'iS'ii'l", ' I! <: ullllil.
' j ..... ^ - > , b ปซ; inm, i "Siiinii' ; x is,;:: ...... : 11 1
'.,"':"!; ;!|'i , '"' '' "!""'
I '
i, iinv):- '.iii.w.iv ;niBi. iiiiiiiiiiiiir'' J....L .:'"! n ; \ปu f ' *"*, j; t
;, .',,1; ".KM .niji. 'iii-iiit'i:, i iijiiiiii IIIIIIIIH -i " !,i ;,; vi'My.1', .i:i ' : ;i ."r. . .', -
LB;<1 in' 'i; MiSii!.;,.'!", ป,r j]ป'. Mill ..Li.!) : "f ซ'; '""I" ''. W' S' .'I , I' t '"Iv i
ijl:';' li, I
I
2-78
III II "I'f ' ," ', '' .I, Tl|.;".." i'' 1 ' '.III' Off ' '
Geochemical Controls
1 :'iiHiiiii"' . T, ; ' :i' r '^rjiinriii;! '.i. 'a ii|| i i n i i n ini in
' i PL if, ii!1 lira1
iii:;:'ii:.|l!ni \< "'""
1 , '! If "''.nli'S ill'i1''1!.!..:!1: I'1'" !'"' ii1'..,. .illii'Millr!!!'."', ' '
-------
Coal Reminins BMP Guidance Manual
2.4 Special Handling
Special handling at surface mines encompasses the selection, handling, and controlled placement
of acid-producing and/or calcareous rock. The primary purpose of special handling is to place
acidic or alkaline strata in such a way as to minimize acid production and transport, and to
maximize the alkalinity generation within the mine spoil water.
Special handling is often used in conjunction with other acid mine drainage prevention
techniques such as alkaline addition, water management (e.g., pit floor drains), and surface
reclamation (e.g., slope grading to promote runoff) to improve the water quality. For example,
special handling, in the absence of calcareous material, cannot by itself produce alkaline
drainage. Thus, where calcareous strata are absent, offsite calcareous material can be imported to
offset these natural deficiencies in acid-neutralizing rocks. Pit floor drains can be used to
engineer where the post-mining water table will re-establish within the spoil, thus assuring that
special handled material will remain above the water table.
Special handling is a common practice, occurring on at least 35 of the 61 mines included in the
EPA Remining Database (Appendix A and Table 2.4a). It affected at least 78 of 231 discharges
in Pennsylvania (Appendix B, Pennsylvania Remining Site Study). An examination of both
databases shows that special handling is not a "stand-alone" BMP. It is always used in
conjunction with other BMPs.
Geochemical Controls
2-79
-------
'Still; Siiiil'i.fli'llillF"''
Coal Remitting BMP Guidance Manual
Table 2.4a: EPA Remining Database (Appendix A), Special Handling of Toxic/Acid
Forming Materials
- "",. 7.. .;. -::, ;'" . ,
SW^ofe' f '. I
ili'lI'LHIIi! i Illlllllll" 11 'jfnr !"'l::!! I'!"1' ., Ill
.iSBiWM'^Hilf " , " i
'II1'? ^WJHW !.'.9>! i!1
'StyrfBMi* -a:,: is
iHiliBMir.1 7!i'r 11
:iiiiiia^^^^^^^^ 'i'jj'ii::
W HffiTMl
.iiiisi'j1'!!..' iiiiK; : a , r
'lil'U'! 1 I " .I" ''11' I'i"1!!!! i! ' illlilni,
]ซ'l. Wili'il'. , It is,:,!! 'li ' li!
iti'i,,'* LifiiiiL 'Hi (in!: :.' ill
i'liiin '? i! T'lLiM1"1. niniisiiii'1'!; y ' ii':
', Mr :| iiiil, Li'ii ,!!!, 1 II", " Illlllii1
, 'Mlilillll' 1 if |!|,!f", ''If |,i,i , illill
Uk;i,tfr"ฃ'k*ut i, " ,:,!
til ". '"Ml
IB:1'!,: ,:]:'!!! IIB1'!', i; f.l
;^|Mf '."'ซ r ":1
I'll I'Sil'i'1' 'l"l:l||ii iii iil'U'lE , 1 ' *, '' 1 "
iiiriJiiiif: tiK 'V ir
ipfl IVffljr I'
ilS^i'liiiii'H ''-'liiliS1 f?*,'VI
i;jป:ll#K1'1 ""'HI' , ' -lill
Moll l" 1 IBH!" 1,," IM"T ' ""!"
i 'IFiF"!'1' :ซซ;,' 'Si!'; ' ;'j 'III
''i'llili1: JiViii I11!1 , 'liHIli' i ' : 11
'mllHInl I: .hil'K.i,, ,i!!!i' mi,: '' ;l|"
''''?!'.!!f;;:i1''1 ' ~,fif ' " "
iinn/'i "; i linn Ji:1! '7 ;" ซซ!,' nil
liiJiiiiriiil'ifF vlil'" '.: H "i
'flilt'll' MlBI'l:, ilMl:!)' ' ' "'I 111
i iiiiiii'"'!':!'''!!' , Bii;1' ' 'liL
ID
AL
(2)
AL
(7)
AL
(10)
AL
(11)
AL
(14)
KY
(1)
KY
(2)
KY
(3)
KY
(4)
PA
(1)
Type of
Mine
Surface
Surface
Surface
Auger
Surface
Surface
Coal
Refuse
Disp.
Surface
Coal
Refuse
Repr.
Surface
Auger
Surface
Auger
Refuse
Storage
Surface
Auger
Surface
Mine
Closure
Date
3/90
5/92
12/95
No
mining
taking
place.
10/89
Active
Active
Shut
down-
11/98
Active
10/98
Cover
Material
4' Non-toxic
Yes
4' clay over
fines
4' over rest
4' Non-toxic
4'
4' Non-toxic
4' Non-toxic
5' Non-toxic
Placement
On pit floor
On pit floor
Against
Highwall
10' above pit
floor; 10'
from
highwall
Blending
of
Overburden
Yes
Other
Major
BMPs
Regrading
Revegetation
Terraces
Regrading
Revegetation
Regrading
Revegetation
Temp.
Diversions
Old washer
fines to be
relocated.
Alkaline
addition
Regrading
Revegetation
Regrading
Revegetation
Reฐrading
Revegetation
Daylighting
Regrading
Revegetation
Regrading
Revegetation
Seals
Revegetation
Daylighting
Alk. Addition
Clay Seals
Comments
Reclamation
will occur
through a
party other
than the
mining
company
Shut down due
to low coal
demand. Will
be reopened.
Acid material
minimal
Alternating
layers of 2 ft
"toxic", 2 ft
clean spoil
If! ( "I ill ill1:;1,;'::' W' iiiiiiiii - 'I'liiii ' MJI Ti wn / ( SF1:. "sli
sail '"iii. t
;, riii.1 &: inn :.'
. "li; ciai'i !!"!,ซ ": ...... iiiii"
Ti/Sia': ..... ii* '''K ..... :'' ftW
i "r'f. "i*11! > fi iitii',;
;.: ' .!'ป' : /}. ' i;l.,,i : : l'1,;;ii'1f -
-'! ' sit ..... :? ...... Li
); :'" 1; * ;!! ....... i; .. i;:1: iS y.TBi
-------
Coal Reminine BMP Guidance Manual
ID
PA
(3)
PA
(5)
PA
(6)
PA
(V)
PA
(8)
PA
(9)
PA
(10)
PA
(11)
PA
(13)
PA
(19)
TN
(1)
TN
(4)
Type of
Mine
Surface
Surface
Surface
Auger
Surface
Auger
Coal
Refuse
Surface
Surface
Rock
Surface
Surface
Auger
Surface
Auger
Surface
Surface
Auger ,
Surface
Auger
Mine
Closure
Date
6/98
4/98
8/96
5/96
Active
Active
11/95
Active
1996
Active
Active
Active
Cover
Material
4' Non-toxic
4' Non-toxic
15' Neutral
Spoil;
2' Clay
Shield
Yes
4' Clean Fill
10'
Non-acid
strata
Placement
10' above pit
floor
20' above
ground water;
10' from
highwall
15' above pit
floor;
15' from
highwall
Above
ground water
25' above pit
floor
70' above
ground water
10'
On pit floor
Blending
of
Overburden
Yes
Other
Major
BMPs
Regrading
Revegetation
Daylighting
Clay Seals
Regrading
Revegetation
Regrading
Revegetation
Daylighting
Regrading
Revegetation
Daylighting
Alk. Addition
Regrading
Revegetation
Daylighting
Alk. Addition
Regrading
Revegetation
Daylighting
Alk. Addition
Biosolids
Regrading
Revegetation
Scarification
Bactericide
Regrading
Revegetation
Daylighting
Alk. Addition
Regrading
Revegetation
Alk. Addition
Backfill
Drains
Alk. Addition
Backfill Inun.
Comments
Alternating
layers of 2 ft
"toxic", 2 ft
clean spoil
Alternating
layers of 2 ft
"toxic", 2 ft
clean spoil
25 T/ac Lime
added 24"
Toxic
30" Clean
Geochemical Controls
2-81
-------
Coal Remining BMP Guidance Manual
i "PI
IIIHil" .11 nil:!!1
ID
VA
(1)
VA
(2)
VA
(3)
VA
(4)
VA
(6)
VA
(7)
WV
(1)
WV
(4)
WV
(5)
wv
(6)
WV
<7)
El!*1 <1 ' I,,'1
Type of
Mine
Surface
Auger
Surface
Auger
Surface
Auger
Surface
Surface
Surface
Surface
Deep
Surface
Surface
Ash
Disposa
1
Surface
Surface
u , iH.'.iiiii'i minim
Mine
Closure
Date
10/98
12/93
4/92
88/90
Active
Active
Active
11/95
Active
Active
6/87
l\ ' 1' ",' llliPir
Cover
Material
4' Non-toxic
4' Non-toxic
Yes
4' Non-toxic
4' Non-toxic
6' Non-toxic
Calcareous
rock
1' non-toxic
10'
it : , M ' 'i "
Placement
4' above pit
floor; 4' from
highwall; not
in bottom
fills
On pit floor
Against
highwall
On pit floor
12-15'
II ill ,' '"1 ' , ' jllK
Blending
of
Overburden
Yes
Surround
w/calcareous
rock
Blend
w/calcareous
rock
Surround
w/calcareous
rock
I11;1,! ,,1'E ,11 II!' "!: / ,'!" illlll'l 'i'1'lh
Other
Major
BMPs
Regrading
Revegetation
Daylighting
Regrading
Revegetation
Topsoil Repl.
Regrading
Revegetation
Regrading
Revegetation
Bactericide
Underdrains
Regrading
Revegetation
Underdrains
Diversions
Compaction
Regrading
Revegetation
Daylighting
Drainage
Regrading
Revegetation
Daylighting
Alk. Addition
Regrading
Revegetation
Sed. Ditches
Regrading
Revegetation
ALD
Alk. Addition
Regrading
Revegetation
Alk. Addition
Regrading
Revegetation
'ป "ป"' l *< '
Comments
Excess of NP
24" Acid
i1! ill IL, i'i., i '.. .'!, , ii ii
2-82
Geochemical Controls
-------
Coal Remining BMP Guidance Manual
ID
WV
(8)
WV
(9)
Type of
Mine
Surface
Deep
Ash
Disp.
Surface
Mine
Closure
Date
Active
1/91
Cover
Material
4' Non-toxic
Yes
Placement
4' above pit
floor
Yes
Blending
of
Overburden
Mixed w/
calcareous
Other Major
BMPs
Regrading
Revegetation
Alk. Addition
Underdrains
Regrading
Revegetation
Comments
Add Alkaline
Mat'l
Theory
There are essentially four methods of special handling:
Blending: mixing of naturally occurring calcareous and acid producing rocks.
Dark and deep: placement of acidic materials consistently below the water table
High and dry: placement of acidic materials consistently above the water table
Alkaline redistribution: distributing alkaline material from areas with an excess to areas with
a deficiency of neutralizing rock.
These four processes rely on different methods of avoiding acid production. Blending relies on
the presence of a sufficient amount of calcareous rock throughout the overburden to .produce
enough alkalinity to offset acidity production from pyritic rocks. "Dark and deep," or
submergence, relies on the fact that water can contain only a small amount of dissolved oxygen
(at most ~10 mg/L) and that water is therefore an effective barrier to atmospheric oxygen
(Watzlaf, 1992). This lack of oxygen reduces the potential for the pyrite to oxidize and produce
acid mine drainage. "High and dry" is based on the premise that ground water plays a role in the
chemical reaction that takes place to form AMD and also acts as a transport medium. Placement
above the w.ater table cannot preclude the contact of water with pyritic material. Even in the
unsaturated zone, there is gaseous water in the pore gases and ground water can adhere to particle
surfaces hydroscopically. Thus, the primary effect of high and dry is avoidance of the transport
of pyrite weathering products. Alkaline redistribution takes advantage of naturally occurring
Geochemical Controls
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CoalRemining BMP Guidance Manual
i '. ;. i i*
III III 1 i III linl II1 111 I (ill I ii I 11 i 'III II 11 1 ; l:iri!i ;"!!!' Jill! '"lit ซ is i:':! :,! . ill;" ,4:,!!': IliliP1; iflWrlW, i! ;ailt Wf /31II if if: WKW "<' ; <; ปปl 'uln 'ซ!: '
alkaline strata where portions of the mine site lack sufficient neutralizes. This alkaline material
is redistributedsuch that all parts of the site have sufficient alkaline material to preventer
I
;
ail ;
! :ปt ' ^ i; ,; ; t i ,i '.
' .-I ' ....... :F > r> ; . , i' i - ........ > . ! i ',:: ''* .' ....... 'ป : ; ': A^ * ! v ).! ..... '': . .' ..' ;: is , ii; ; ซ si;-; ;>' :;i , . $K , j ; . ; :t ...... ..:. ^ ..... y : mi-
Blending is being used ion at least 5 of the special handling sites listed in Table 6.4a. Blending
.Uir.Eii. J,:,m ....... iU^^^^^^ ..... W"& ........ BY*,E: v'nis ..... ป ...... st..*1*'!! ..... fflfe ...... r ........ > ..... vin? ...... ปf ..... fi^iipft'ji ........ M .......... ป:, ....... iiiปป'!S"i; ....... BfEfc'^i:rsrii ..... a ....... , .......... ..... .
lakes adyantage of naturally-occurring calcareous strata. In its simplest form, mixing of the
strata occurs in the coarse of overburden removal. Blending plans can be more intentional with
!
specific strata targeted to assure adequate mixing.
Typically, in the Appalachians, acidic material is placed above the posFmining water table to
minimize water contact. Calcareous materials, on the other hand, are placed such that their
I
dissolution will be maximized, which can mean placement below the ground-water table.
Combinations of special handling, alkaline addition, water management, and surface reclamation
can allow the mine operator some control over acid- and alkaline-generating processes.
Probably the first special handling concept involved the recognition of black or very dark colored
rocks ajjcl cgal reject ("gob," "bone coal") as potential acid formers. Initially, it was proposed
that the material be buried on the pit floor. Deep burial was thought to prevent contact with
oxygen, and hence shut off acid production. This approach was discussed as early as 1952 by the
Pennsylvania Sanitary Water Board and is shown in Figure 2.4a. The Sanitary Water Board also
recommended highwall diversion ditches, pit floor drains, contemporaneous backfilling, and
grading topography to limit water infiltration.
2-84
Geochemical Controls
; ;;;;: ; ; ;;; ; ;;;;;;: ; ; ;;;: ;;;;;;;;;; ; ;;;;; ; ; ; ;; ; ; ; ; ; : ; ; i ; ; ; [ ; ;
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Coal Remining BMP Guidance Manual
Figure 2.4a: Early Recommendation of the Pennsylvania Sanitary Water Board for
Handling Sulfuritic Material (suggested placement was on the pit floor
under the unreclaimed spoil piles).
After Pennsylvania Sanitary Water Board, September 1952
IWELL COMPACTED SOIL OR CLA
Experience with deep burial of potential acid-forming materials in Pennsylvania showed that
water quality problems were not always eliminated and sometimes were more severe. This is
because of difficulties maintaining a sufficient water table to keep the material submerged, hi
most Appalachian states, special handling strategies began to evolve towards isolation of material
above the post-mining water table with isolation from preferred ground-water flow paths. This
remains the most common special handling technique used in the Appalachians and is illustrated
conceptually in Figure 2.4b.
Geochemical Controls
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Coal Remitting BMP Guidance Manual
Figure 2.4b: High and Dry Placement of Acidic Material (commonly used method of
, il'^JSUi!! Ill' SI !;:i"|Pecial handling in Appalachia).
I1 ". II ii 1:1 l,i,lซli.|lli.|i, Ml. , lliliT I 'l!;;i:: il.*1,'! I, I! II lOIII:
iit.Ki:,fnBr,'i;*fl' Sit Si.;?;,
iiiiii,,,,1111;:':ป; jili!' ;\M.i&4$ '-ili Slii i1'.:!:,!1 Weathers
Illllllill..,!., !il!H^^^^ .lin.;11!!:,:' Illlllll IS' '!'',''!'T!''''n.i'; i.<. ;. iff. 'Mil!']! i ,f
ฃ andstont:
rinw-a*''..$ป*> kin*.".i is
andstont:
and Shale i
Above Final Water Table
" PifFldoT - Water Table
i i 11 ill i
Not to Scale
Modified from J.G. Skousen, et.al.,1987
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:i! '^^i,';,:,;:,i 'Campling and Site Assessment
Special handlhig plans are site specific and should include consideration of the following factors:
r ' 'i'l i iniiii i,;,i", -
'.'J.'': i,'"' "'
"j.,1^ ,, Geologic and Geochemical Conditions: identifying acidity- and alkalinity-generating rocks
i ^' 'i 1 ' i" '
ii " i'- "
in the overburden and determining the distribution, location, and volume of these rocks.
III!1!"1! 1"" '"iii'S":'I1!1'"" i" Sill'1''' till '. I;','!:,; <, ,,,,,,,,: ," w.,,, lt, ,,f t,.,,. ^ ,, rmj,,., , : ,, ,, ,. ;v ,,. , ,,,
Ii1 :, ;:".I i 11 ',, ;r,? lllllli i ;,,: P (fiili"!1, IIS 11 til , *M i: a, ';' i!il|:,f ;; t :if i $ - Iii.1 -'' f.' >,,:] i', i rt ;:::"; i , i' ir;!:::;ป t !,;": -^.'l Vg!I,:" liii'S .if;"
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Illllili, 'ill IHHillt';
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,,,, i,,, ,,,, 11,, ,,,,_ i , v _ i,, ,,. , .Geochemical^ Controls^
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1 ' iiihi ,. , iiiii, ,:,, 'iii1
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Coal Remining BMP Guidance Manual
highest post-mining ground-water elevation in the backfill based on projected spoil
transmissive properties.
Operational Considerations: determining an appropriate mining method(s), sequence of
mining, area to be mined, equipment to be used, and placement and amount of acidic and
alkaline materials.
Field Identification: determination of whether the alkalinity- or acidity-producing rocks be
identified in the field so that they can be properly handled.
Geologic and Geochemical Considerations
Development of a special handling plan requires knowledge of the stratigraphic position, aerial
extent, and total volume of acidity- and alkalinity-generating rocks (See Section 2.1). Horizontal
sampling should be sufficient to define the lateral distribution of calcareous or high-sulfur strata.
Likewise, vertical sampling should be of adequate resolution to discriminate calcareous and high
sulfur strata. Too large a sample interval can result in loss of resolution and an inability to
determine acidic or alkaline rocks. Acid-base accounting (ABA) is the overburden analysis
procedure most commonly used for these determinations, and is discussed in Section 2.1.
Hydrogsologic Conditions
Hydrologic conditions are an important consideration in the design of a special handling plan.
The position of the post-mining water table has bearing on where materials are placed, and is an
important consideration in whether materials should be submerged below the water table or
placed above the water table. Whichever method is chosen, the goal is typically to keep the
material out of the zone of water table fluctuation.
Geochemical Controls
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III i III!!
Coal Remitting BMP Guidance Manual
The information needed to predict the post-mining water table includes a determination of the
type of ground-water system (regional, perched, unsaturated zone). Considerations include
premining ground-water levels, examination of ground-water conditions on nearby mined areas,
relationship fo'aSjacent stteanis" geologic structure, and'water ^gemenT designs in the mine
' '"' ' "'''"""' ' "'' *' ''"" "'"""' 'i "" ' '" 'v'"' L| ' ' *' ' "'' '" r ' ' ' I"11'""''"'" "' '"
plan and pit design. Overburden lithology and mining methods also play a role in the hydrologic
characteristics of mine spoil, which ultimately impacts the post-mining water table.
Table 2.4b is a statistical summary of saturated thickness of ground water in spoil wells. The
I
summary represents data from Kentucky, Ohio, West Virginia and Pennsylvania, with 5, 9,27,
and 83 wells, respectively. Data are from measurements made by Hawkins (1999). The data
have been split into two categories, wells that were developed in spoil less than 15 meters thick
and wells in spoil greater than 15 meters thick. The median saturated thickness for the deeper
wells is twice that for the shallower wells (4 and 2. meters). This difference is significant at the
95 percent confidence limit. The range, however, in both categories is extreme, ranging from a
fraction of a meter to 8 and 11 meters, respectively. The significance for special handling is
profound, The "dark and deep" method will not work where the saturated thickness is a fraction
of a meter. Conversely, "high and dry" will not work where the overburden is-less than 15
rfielefs and the saturated thickness is 8 meters. With a water table this high special handled
WWII iWillili IITtiB : -i iilillU ''lifeF' Xi iilCE'F11!!"! I'!",:" V .rill! 71" Wv."'(!', "I1"'' t.'X. ii'"> '*'.' iil<.iilil ' < >K< filHI,. I'SIIIX^^^^^^^ 3, IF rf>, v ,,, . ., .
fie rooting zone. The values in Table 2.4b are a "snapshot" in time. They were a one-time
|
Pimpling event and do not represent seasonal and climatic variations which would extend the
f^WM in i ,W". m i fittfiK1*!:^* ifi'i'&iifi'iiS' romBitttpw ms 'li^iih^^^^^^^^^^^
l|:angฃ These data, however, provide insights into the variability of saturated thickness in mine
!HB'V*l9F!il*1H,l.' ..**l.i:
>?.'' :ilil|.. H!'!': ' ft' ,! I "I',!
IlliihH ''i'"'Iff1 ,5'"', I Hilll11' ' l,!i::il'
.j! |, .I" .!]!; J" j,1, .1' ,,11, ,ป : .i*;,,!'1 ',ซ'.'"""Ri;1 'ji' '",ฃ: ;!'' V*!!! "1!,, !!'! t,!'' ft1'!! '!!'i
'ijUJi' 11" '|,:rj,"i|, ^1,
i IF' i, i" i'J:iiiI 'Hill'1'1" ''ill!,!1!'1!,'!,,' K"
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111 i"';i ' %~m
Hi:,!:' MI' iiiiiii11 'I'-'i'i'Mhiiiiiyn I'l'i'i1' Minn
i ............ ';,!! ,!!i,l"illl ..... I !,,!,!' ", ' ..... I1"
"'iliilli:1:: x1' ''"I'l 'iii'iililinl 111111:11'', ', IIP"' ",r 'iiiin ilil'Wiu'liMi, II
i i, llllf Jiilii!:! .aiill
JintK^^^^^^^
i, "inn,!' {I! i "iiii'ii'i! '!:, i'';: i ;'""iii! :] i\, vjk >;.ซ,m i , if, ,t( ii iv ii \\, mti.s:
'liliill!,!;!;: IJ1';|j|,,;||i|' ililll"!!!!1 ",,,, IJ!,!, , j, nil,,!,,! |' jliiliiiiiifluli,lilijlin,Ig ElllhiiiliillU^ III','lili| {lliiillli'll,!,,"I'|S^
"Geochemical Controls
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ill Vi'Mili^iililiiPllllliriii .lllllllii!' Wii:" ,'ii
ijl IJiliii,"!!:!!11!.'!!"!! "!' 'Oil! .'nil,: iili ailHI11'lailll'' I
i'!,,i:i n: isiiii'iuj^^^^^ I
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Coal Remining BMP Guidance Mar,
Table 2.4b. Saturated Thickness in Meters for Wells Developed in Appalachian Mine
Spoil. (Hawkins, 1999).
Summary Statistics
Median
Minimum
Maximum
Lower Quartile
Upper Quartile
Number of Wells
Saturated Thickness (meters)
All Wells
2.94
. 0.18
11.03
1.44
4.52
124
Spoil < 15 m Thick
2.08
0.26
8.08
1.30
3.22
69
Spoil > 15 m Thick
4.08
0.18
11.03
2.55
5.49
55
It is also important to understand the sources of ground-water recharge. These sources include
infiltrating precipitation, ground-water recharge through the final highwall or adjacent mined
area, and upward flow through the pit floor. Monitoring wells, piezometers and aquifer tests may
be necessary to provide insight into ground-water conditions. However, one should be cognizant
that ground-water flow in the coal fields of the Appalachians, is largely fracture-controlled and
that wells not located in fractures may underestimate the amount of water present and it's
stratigraphic location. Another technique that can be used to estimate the amount of water
present is the determination of flows from cropline springs. Insights can also be gained by
looking at post-mining water conditions at nearby mines with similar geologic, hydrologic, and
mining conditions.
Ground-water conditions are not "static" and vary seasonally and in response to recharge events.
Monitoring should be sufficient to account for these variations. If, for example, the chosen
placement technique is submergence below the ground-water table, and monitoring occurred
only during the period of seasonally-high water, there may be times of the year when the water
table would be below the placement position, and the special handled material would not be
submerged. Alternatively, if the design is "high and dry" and monitoring only took place when
Geochemical Controls
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III! Kll
Coal Rtimining BMP Guidance Manual
the water table Fas low, there may Be times of the year when the material is within or below the
ground-water table.
iriiiiiilll'liii i i"1!!!,'",!:!:!
,; IT , 'iiiUiiij; ..... licoi: ........ i P;,:.;, T: "; Jiir ;ป I; Wit ,,
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Operational Considerations
ill n 11 ii i 11 mi i i in i in n r liiniM Aiii^
Implementation of a special handling plan is also dependent on operational considerations.
These considerations include: trie amount of area to be mined, total overburden thickness,
amount of material to be special handled, sequence of mining, time needed to complete mining,
1 M i i n i in ill in ill ii (n n i vi -*ซ' vr
the need for blasting, the mining method, and equipment. The equipment should be appropriate
: II
for the special handling plan and site conditions. For example, truck and loader operations are
able to easily remove distinct portions of overburden and to transport the overburden from one
area of .a mineto another.Thistype of segregation is not performed as easily with a dragline.
Operational considerations will be discussed in more detail under Section 2.4.1.
I
liilill!!'1!'
1*2.4.1 Implementation Guidelines
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'> ซ /Jtlllli. lit:""i"1"-'" '*< "M ,''"'i' 'A1-1' " :i' "i: l'llia:|i !|"!U"i!1/ ': "' "i i!l"::ii!i i"' liil" '"il' i'11 "ff V' :'I|:''' ;i'! i1'1"1!1"1 TS;I!I'' J';|K|G j v::' ' I
rior to developing a special handling plan the overburden should be sampled and acid- and
-^-v'f t - alkaline^forming strata should be identified. Ground-water conditions should be well
iiii;, ',.' "i?1^ muie'd" shoul3 tie considered.1 Only then can "a plan be
lillTlim, '''' tii\i!i^ViiRiliiSiv,i!K lllllllllllli'i"Wv: ' iiiiti ,:<', ! i: 'F ;:m ;, fi'iiiii'iii:,!>iiiiSiI'rii'^iiii'iriiiiin: i ifnb^riA^^ni i": ":ป>smx
i"' niniiiปi'ii<"", "iiaiHi'M; I'lXiihiiiiniii' i 'iiniiiinniiii'TiiiiiTi'iiiiiiriiji iiLiKjii'Lijui''.-!*!!::!'''!!!' ii;;:!!.!,:: M:"I ,T ; , JIM n iiiii'iiE'i'irwi 'Mujyy iiiiiMr,,' i, 'inyBinii.!!!!,,' wi' *.*i TJ ,,IPI ,' ' .Mik,^, nj ,i^ ""v'ji1 VT
designed and the appropriate mining methods determined. Special handling plans should be
ililnlll ' I
!
I cfe simple, and easily implemented by field personnel. Maps and cross-sections should show
the positions of the materials to be special handled, and locations where these materials are to be
jfjpfaced. The materials should be readily identifiable in the field by color, position or rock type.
' ''I'liliii II 111 ill I 111 i 111 I III II I I II I 111 II Pill I ill I II i III i ;,/; i I
Ian should be logistically feasible and field verifiable.
:i JUKI i aw:1!: J K
Geologic and Geochemical Considerations
, MlllllmlM ...,!i,:n Illll'i n
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:) ^^^^^^^^ * ..... \ jr^T?งr ;; *nr ; ;ซ ; :,,i , i : LSI ..... j ..... fsw^t: >t *w , > im * ......... H ........ iKiaiiii vi. -M ..... 41 ....... ' ....... !'^si'-, -ii?' ..... &* > ^
Stratigraphic position of the material is an important planning consideration. If the material lies
immediately above or below the coal seam to be mined, segregation is usually not a problem.
'M!!i!"'fflrt'JKll8i'fI!i ..... ~msm ..... lilS'? ..... '^j^/i's^ifJ ..... 'ซifi;il'ii'!ii';,f,VKi^'S:;it! ...... 'l ..... ป ...... IM^'.lil^llW^r/ifflBm.^'rK ...... i, ttW
Segregating strata located in other positions above a coal seam may be more problematic.
Geochemical Controls
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Coal Remining BMP Guidance Manual
Feasibility will require consideration of equipment and blasting plans, how readily identifiable
the strata is in the field, and costs of implementing the plan. "Fizz tests" using dilute
hydrochloric acid can be performed in the field to identify alkaline strata. Unfortunately there is
no comparable filed test for acid-forming strata.
Hydrogeologic Conditions
In situations where the operator is attempting to special handle acid-forming material by
submergence, the length of time required for the post-mining water table to re-establish is
important. If the operator wishes to place this material above the post-mining water table timing
of water table reestablishment is not important.
The contribution to the post-mining water table from infiltrating precipitation during the first few
years following reclamation will be less than that for unmined areas. Jorgensen and Gardner
(1987), Guebert and Gardner (1992), and Ritter and Gardner (1993) investigated infiltration and
runoff on newly reclaimed surface mines in central Pennsylvania. They found that infiltration
rates on newly reclaimed mine soils are an order of magnitude lower than adjacent, undisturbed
soil. However, within four years after reclamation, infiltration rates on some mine surfaces
approach pre-mined rates (8 crn/hr). During the topsoiling operation, the soil is compacted by
the equipment. This compaction promotes runoff. During freeze/thaw and wet/dry cycles,
macropores develop in the surface soils which promote infiltration. The reestablishment of soil
structure and plants also promotes infiltration.
Re-establishment of a post-mining water table will probably occur most rapidly for those mines
where the lowest seam mined lies beneath the regional water table. Once the pumps are shut off,
the regional water table will typically re-establish itself in a relatively short period of time. It
becomes somewhat more difficult to predict the configuration and rate of rebound of the post-
mining water table for mines with aquifers perched above the regional water table.
Geochemical Controls
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Coal Remitting BMP Guidance Manual
'"'''lll'Bi!,!"1"'!!!!!!!!!!!!!1! !" U's,!!!;"',
illl'illliil, i!!iซl ...... I, , , . llป Jllii,,1
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I
Where the mine is situated above the regional ground-water table, the hydraulic characteristics of
Ii' i. .|li. i: ' 111: WtS ICilllF' ill'111 ,;[* i' ! ,t, It: V" T] r TI "t1! ,: >, 1 " i It! " *,:ซ- " - -. 'i > ; 'i' i , ' -;, . K ป , i, as, ' no: >. s * ,: i ปซin , iซ,
Ik!' |ซ ; fcli '" y" 'ป,'iii1' ''ail':1!! IIIIISI*1' lit i' Ii i'1:! 4 3 'I ""ป ': l"':i"! 'livfirJ :,, t 'i,,,'1"!"!'1"1 ' "!ซ'pi!:'.|'"i.jii i'" ;,!;, '::,'"! "! ' ,';''" i"1' h!' f\K iW, ซซ a'llRiL.llliii;1"'1!1;!*1:,;;, JiPmiLn'lW'inni' tnt'l'M1'''..'Ih'illl1'1!!, '. .ffiJ'il,1* "'' ,! i1 !liii'"iill' ' ll;l M': ::ii SEI'^IIOIII
the pit floor will determine whether a post-mining water fable will be intermittent or permanent.
SIIIC'I A' I
II'11 I'11" ' ' 'I Illl I
I11!!""*: ; ''fill!!:!' Till!?1'' ' l!l>:"!<
I'liiiirT'iKiF' ' in nil
If the pit floor material is a thick underclay, it will tend to serve as an aquitard inhibiting further
||| 'dpwnwajS^inigration. In other cases, the'floor might be massive, fractured' sandstone, which will
,' jljjl 'allow,^e'dowaward percolation of ground water:' The post-mining, ground-water table is
dependent on me structure of me lowest mined coal seam and me final highwall configuration.
Where a down-dip highwall remains after mining and the pit floor retards vertical percolation,
grdufid water may become impounded on the pit floor against the highwall, result ing in a higher
pSst-rMning water table than is typically the case with an up-dip highwall. In the case where a
downdip highwall remains after mining and conditions are present which promote impounding of
the ground water against the highwall, the "rule of thumb" placement 10 to 20 feet above the pit
!!I I
floor may be inadequate. If the intention is to keep the ground-water table low, it may be
desirable to change the orientation and/or location of the final highwall to avoid impounding
mi.!'' r::! wifi'jfcjr.ciiw ,ifliปi-i?" .,., , , -,ป - ,, ., S ,., t ,,,,.
incorporate; underdraihs to rninimize ground-water buildup in the backfill.
Ill '.'fji; MI" i;1: j:1.'1 <, us ปs, ^ ':.;: r! ? ?; ? f j ;: "n ii i . :J. ~ l f ' ;| ? % :i"'",, ฃ,!iPtli>ii :;:; ; riii; {; IN'' J>' Ii: i" \51Fli"!' :
;; Jill! i'
Ji'Sjiv fjl
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Spoil hydrology plays a role in the configuration of the water table. Low-permeability spoil will
tend to maintain a higher water table than high permeability spoil. However, most mine spoil is
highly permeable compared to undisturbed strata.
ii IH1 IBfli'iif iiiiji;;' i-li.'
i|||ii|i|i|||HMI ;,,,|| i''' 1, , ,''1,111'',11|| ' ,11 Jl'1 ll'll|i||PIIIIIIII''l|i' lUITilLi, !, " 'i, ' ,'l!i||||,', ,;iii: "'ปl 'r1 l! 'Mil'I, ! '<
Operational Considerations
Him nli, ,> r ,,, .ni, , I,,' , ,,n ' 'i , ,ii,
The mining plan is often based on the configuration of the land that is to be mined rather than the
optimum configuration for overburden and coal removal. The stratigraphic and area! distribution
of the aci3- and alkaline-forming materials, as they relate to the mining plan, are important in
[[[ ...................................... ................. [[[ I ................ ........ n ................ ...............................
determining how these strata can be special handled and how much is to be segregated.
However, several pit orientations are often possible, and some may be more efficient for a
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particular handling plan.
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Typically, when blasting, the total overburden column above the coal is broken up in one shot
(lift). However, if the strata to be segregated lies at some distance above the coal, it will
i in
III 1111
.'
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Coal Reminins BMP Guidance Manual
probably be necessary to blast in multiple lifts. The first lift removes the overburden above the
unit to be special handled, and the unit to be special handled is removed separately. The
remaining overburden above the coal is then removed. This process can easily increase blasting
costs by more than 50 percent, and may result in poor rock breakage at the top of the lift because
of stemming requirements (Getto, 1998). Blast hole "stemming" refers to material that is placed
in the shot hole above the explosive. Stemming confines the energy of the explosion to the area
around the explosive.
When potentially acid-forming strata are exposed, rapidly covering the strata helps prevent the
onset of acid-forming reactions (Skousen and others, 1987). Perry and others (1997) examined
seven sites with special handling and found timeliness of reclamation to have some influence on
water quality. Extended exposure of unreclaimed spoil to infiltration and circulation of water
and to oxygen apparently allows accelerated acid production.
In general, segregation of spoil material is more difficult when using a dragline. In many cases,
dragline operators do not have visual contact with the spoil that is being loaded. Also, typically,
for a dragline to remove material it has to be "shot" and this often results in random material
mixing. Even without mixing, draglines are not good at separating discrete stratigraphic layers.
"Blending" of overburden is often appropriate where the alkaline and acidic overburden occur in
proximity. Blending may not require anything out of the ordinary and may occur simply as a
consequence of overburden removal and replacement.
Two overburden removal plans are shown in Figures 6.4.la and 6.4.Ib. In Figure 6.4.la, acidic
material is located in the upper part of the rock column and requires separate removal. In Figure
6.1.4b, acid material is located directly above the coal. In the later scenario the entire overlying
rock column can be blasted and removed in one lift, resulting in a blending of the alkaline- and
acid-forming material.
Geochemical Controls
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Coal Remitting BMP Guidance Manual
Figures 2.4.1a and 2.4.1b:
Overburden Handling Procedures Depending on
StratigraphicPosition of Acid-producing Materials (figures
show the types of equipment that may be appropriate for
handling the overburden).
ROCKS TO BE MINED
III I
EQUIPMENT AND METHODS JO BE USED
Removed with a loader, dozer, or pan
Ripped and removed with a loader or dozer, and
depending on acid level could possibly be blended
Blasted and moved with loader, dozer
and /or dragline or shoval. and could bo
blanded with tha acid units above
Coal material loft in mine pits is moved by
loader to acid material disposal area
Minimize the disturbance to the pavement
and treat with alkaline lower permeability material
ROCKS TO BE MINED
Removed with a loader, dozer, or pan
Blasted and moved with loader, dozer
and /or dragline or shovel, and could be
blended with the acid units
Blasted and removed with overlying alkaline materiel
. ,., ..,,,. , , , ,, , ,, v I,,
EQUIPMENT AND METHODS TO BE USED
Ripped and removed with a. loader or dozer, and
depending on acid level could possibly be blended
Coal material left In mine pits is moved by
loader to acid material disposal area
Minimize the disturbance to the pavement
and treat with alkaline lower permeability material
2-94
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Coal Remining BMP Guidance Manual
Another operational constraint occurs when the alkaline material is located beneath the coal
being mined. Ripping (disaggregating) the pit floor can be done to incorporate alkaline material
into the mine backfill at sites where alkaline strata exist below the lowest coal seam to be mined.
This method involves removing the coal and ripping the pit floor to expose the alkaline strata to
ground water on the pit floor. It is a suitable practice if the pit floor or underclay is not acid
forming. The operator should have equipment capable of ripping the pit floor to the needed
depth and sufficiently breaking up the alkaline zone. Typically, an average size dozer can rip to
a depth of approximately 3 feet (1 m), while a D-l 1 dozer is capable of ripping to greater depths.
If the alkaline material is at a depth greater than the depth accessible by ripping, the overlying
material will need to be removed prior to ripping.
Limestone is generally a durable rock and is resistant to abrasion. When ripped, limestone tends
to be of a much larger size than is normally associated with alkaline addition or redistribution,
hence, increased surface area is limited. This method is adequate for mines where alkaline
deficiencies are small, as it may have a limited effect on ground-water quality when compared to
alkaline addition of fine-grained material or alkaline redistribution in the spoil. Section 2.4.4,
Case Study 6 discusses a mine where the pit floor was ripped to expose alkaline material. This
site is a rare case in which a Pennsylvania remining site resulted in degradation of water quality.
Special handling is an overburden management technique by which acidic and alkaline materials
are selectively placed in the backfill. Special handling is rarely used alone and is typically used
with other BMPs. Special handling techniques and associated BMPs include:
Relocation of potentially acid-forming strata above the anticipated post-mining ground-water
table,
Constructing "pods" of acid-forming materials
Capping the acid-forming material
Submergence or flooding;
Blending including alkaline redistribution;
Operational considerations; and
Geochemical Controls
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Coal fiemining BMP Guidance Manual
Incorporation with other BMPs such as alkaline addition, daylighting and surface- and
ground-water management.
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Placement above the water table and encapsulation
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Placen^nt of acidic materials above the water table using segregation, isolation, and |
encapsulation techniques minimizes contact between acid-forming material and ground water.
Special placement usually occurs in "pods" or discrete piles that are located above the expected
post-mining water table in the backfill; thus it is often referred to as the "high and dry" method.
A few mines have constructed liners and caps that are designed to prevent ground-water contact
'linn: i ,!! i> ' H!, ,, iSiFi";,:' I- ,; "',:, it:,i,; 'Uiiiii ...iiiiilii. ,>i ' 'in'rii:,, HID,!" ::i ic1;,. :m ;.* 'in : ..'u'. "i,,, K., <, > '..-.'. '.' . :-' "Hii:1!'!! ..':A.|Iป:'IIซ^ ;.>:'-i" ""fj'1:, .:'( rink;, iwaii!::)' i h !".iniii "..ani la uiiiiiiiiiiii i 'IIIB-'..! ...i I
3vith the acid-fQiniing materials. This method is encapsulation. Segregation and isolation from
the ground-water system does not totally prevent pyrite oxidation. Oxygen, microbes and water
I IIISIK !* H"! > '.!!' I:|:1|-\<:'!!!V '' i i n i ill i n i |i i i n i i i 11 i 11 ill in ill i
nt in the pods. Segregation and isolation are directed at preventing massive
:!1i^
kw y ^rSpwnward ..... leaching, or ^upward migration ofoxid' ation products. The technique-is illustrated and
described in Figure 2A.lc.
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2-96
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Coal Remining BMP Guidance Manual
Figure 2.4. Ic: Three-dimensional Conceptual View of High and Dry Placement of Acid-
forming Materials
SEGREGATION AND ISOLATION (HIGH AND DRY) TECHNIQUES
STEPS INVOLVED IN SPECIAL HANDLING ACID MATERIALS
1) Conduct drilling and blasting to expose acid materials,
2) Remove acid materials with a loader or dozer,
3) Construct the disposal site in the backfill where:
- at least 10-20 feet from the highwall,
- above the final water table to be developed in the post mining backfill,
- out of the root zone probably at least 10- feet below the surface
- away from natural drains that would flow across the post mining backfill
4) Place the acid material either in on the constructed pad in the backfill or in a
in a temporary storage for transport offsite or to another part of the permit
5} Add alkaline material to acid material to reduce acid generation, and
6) Complete the reclamation and revegetation as quickly as possibly
Construction of acid-forming material pods is one of the oldest techniques used to isolate
potentially acidic strata. The purpose is to inhibit percolation or recharge of ground water
through the potentially acid-forming strata. Pods are constructed in compacted layers, sometimes
with potentially acid-forming material alternated with alkaline strata. Pods are placed above the
highest anticipated ground-water elevation in the backfill, and usually at least 25 feet away from
the final highwalls and lowwalls and 10 feet'from the surface. Potentially acid-forming material
Geochemical Controls
2-97
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*a!! needs to be rapidly excavated and covered to prevent prolonged exposure of the materials to
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;; " -i;",, ^.pxygcn and water.
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andv
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: --' : "''' - Cravotta and others (1 _994ariand. 1994b) compared the abilities of a dragline versus trucks and
liihliliiillF ''ST:,! i, ilix, iSBW^SiW ifWiฃ iiii: '.ii! '*ฅ'$ Si I Sn '.it ilwWB U"1 iiiiif'Si' :ii,' SiSi :>: fปfSi Ii iil
areas of the same mine to special handle acid-forming strata. Both
":;:"handling methods tended to invert the original rock column. Where loaders were used, pyritic
ISiiE^^^^^ liiiiii::1!::]!)! :,Iii'iiiiiI>'!H &&.:iifiii'':*fti ',iw I
mi{ฃitir.!!5H. ;.w ;li:ih,งle,was. selectjyely placed in pods near the final surface, and only low sulfur material was near
KlWIlin^ "III Fill!1 "'ini'l'i'.'ซIIIIIIIIIIIIIIIlKI' Jlill'lilllt'liillliiiJI'lllfllllll'IIIIUi 1:911111 IIIIIIIElliiiIl^lllillllllH1,, i iiilliiiliUVIB1' jiiiiiiiiiiiL'iiHiiii, , niiiiiiiiinL! iiiiiiiwi WILMI in,, rjiuri inn ni'iiuni i t"t> rn, iiiiiii'iiiiiiiiiiiiiiiiM''''!!!,!!'!,II.IIIIIIIIIIJIIII'IIIIIIII.IMIIIIIIIIIIIIIIIIII '"."iihiinniii iiiiiiai'iini mi, i ,- i, | , j/ < < .,<ซ nuซ ':f$ ป^i^1r?*1i|lKffl:mvซllliTfi"i4 lซซJIM'iil'ซซfiTi*ปf Wffl i
aundsevere .AMD .formation ...associated with segregated, but improperly isolated pyritic
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lalerial. Subsequent drilling and ground-water sampling confirmed that the AMD associated
^(!ltf;raiwJBl.':; Jljti'|!ira^WaBWffl;;W- |ง.:t";;,|,-! i .;;JC'if'ฃ V"I iiซ;!*$,;S M%!i I JiM.';.*!:iglT;n'?Iซl^'!HPii,9ij;^.SSWRTi1'..;;!.:".*!' ป'!!!ซ;ป;
|ith;thes:einipro^ severe tihian AMD generated elsewhere oil the
|tep i jt^many cases, the operator co^nfirmed that the pods were segregated acid-forming
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Placement of acidic material into a contour surface mine backfill should fall within a projected
target zone (See Figure 2.4. Id). The bounds of this zone are established by the distance from the
highwall, height above the pit floor, post-mining water table, the depth below the root zone, the
distance from the outcrop, and the distance from reestablished drainageways and various barrier
111 I I III II 111 llllllllll 'III II 111 111 III I Hill I 11 IIII
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2-98
Geochemical Controls
liiiiiii iiiiiiiiiiiiii iiiiiiiii i iiiiiii iii i i in iiii 11 n
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Coal Remining BMP Guidance Manual
areas. In the example provided in Figure 2.4. Id, a simplistic approach is demonstrated to
indicate the maximum amount of acid material that can be placed in the target zone.
Figure 2.4.1d: Projected Target Zone Determination for Placement of Acid Forming
Material within the Backfill
Highwal!
Not To Scale
Modified from O.<3. Skousen, et.al..19e7
200ft
Total Mined Area Triangle = 6000 sq ft <
Acid Material Target Area Triangle = 1900 sq ft
32% of the Backfill is Available for Disposal
Reduction of the Target Zone Due to the Angle of Repose (Loader) Limitation:
27% of the Backfill is Available for Disposal
Geochemical Controls
2-99
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i " '
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Coal Returning 'BMP Guidance Manual
The values used for the Total Mined Area Triangle (TMAT) include:
Maximum Highwall Height 60 feet
Coal Thickness 4 feet
Stripping Ratio 15:1
Landslope 30%
Calculated Maximum Pit Floor Width 200 feet
The values for the Acid Material Target (Area Triangle TMAT) include:
Distance from the highwall 20 feet
Distance above the pit floor 10 feet
Depth below the root zone 10 feet
Distance above the post-mining water table Variable
Away from re-established surface drains Variable
P111 I (lil I"
111 ill
The TMAT square footage value is 6000 feet2 using the maximum pit floor width and highwall
n n in 111 iin iiinii|i| ii ii n ill in in i n i ii i linn i i i 11 i i i n n i n i in 11 in i iiii|iiiiiiin
height. The maximum height of the TMAT to which the acid material could be placed (and still
meet the segregation and isolation disposal conditions) is 34 feet on the side nearest the highwall.
The maximum width of the TMAT is 112 feet. At most, only 32 percent (roughly one third) of
j ;.;. : ;;;;: ;;:; ;;;; ;;;;;,;,;;, ; :.;, ,: ;;{; , ., n ; ;,
the total mined area can be used for acid material placement. This value will change depending
on highwall height, land slope and placement constraints. As a general rule, as land slope
increases, the size of the target area for acidic material will decrease.
Further reductions in the amount of acidic material placement result from the practicalities of
handling and construction of the top portion of the TMAT. If the material is dumped at the angle
of repose (assumed to be 30ฐ) before being compacted, a portion of the TMAT would not be
available for use during placement. This zone (cross-hatched area in Figure 2.4.4b) represents
about 5 percent of the fill cross section. Under these conditions, no more than approximately 27
percent of the total backfill is available for acidic material placement. This target triangle area
for acidic material placement is not continuous around a hill (along the contour) because of the
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natural drainageways which occur every few hundred feet in the Appalachian Plateau. Other
I
obstacles such as gas wells, gas lines, power lines, and houses may further reduce available
i
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2-100
ill
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I III1
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Coal Remining BMP Guidance Manual
placement area, and further limit the lateral extent of placement. A high water table will often
require placement more than 10 feet above the pit floor. Due to these constraints, the acid
material should be less than 20 percent of the material to be backfilled.
Meek (1994) monitored acid production on surface mined areas with segregation and several
different alkaline amendments. Acid load, on an area with segregation, was reduced about 50
percent compared to a control area with no segregation or alkaline addition.
Phelps and Saperstein (1982) suggested that pods should have a bulk density of 1.1 to 1.5 times
the surrounding spoil to minimize infiltration. These investigators also observed that the highest
spoil bulk densities occurred at 50 to 80 percent depth of spoil for most mining methods. They
suggested that the high density spoil zones should be favorable locations for pods, if hydrologic
requirements are satisfied.
Schueck and others (1996) reported on attempts to grout buried refuse with fluidized bed
combustion ash as a method of isolating pods after the fact. This was done on a site where the
lower Kittanning coal seam was mined and most of the overburden is apparently acid-forming.
Grout was injected directly into the buried pods to fill the void spaces and directly coat the
refuse. Grout caps were also constructed over several of the pods. Combined grouting affected
only 5 percent of the site but resulted in a 50 to 60 percent decrease in acid concentration in
downgradient monitoring wells.
Short exposure time before burial and reclamation can reduce weathering and acid generation.
As the acid-forming material remains exposed, rocks break down exposing more surface area,
and weathering proceeds to produce acid products along with the subsequent buildup of soluble
acid salts. In practice, potentially acid-forming materials are often stockpiled until enough
material to start pod construction is accumulated. To reduce exposure, some mines in
Pennsylvania construct temporary stockpiles covered with soil and vegetation, or cover the
material with lime for neutralization.
Geochemical Controls
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Coal Remining BMP Guidance Manual
^l^enacid^onrung material is handled from a cut, the construction of pods should be concurrent
with mining and backfilling. This ensures that acid-forming material is rapidly buried. Rose and
others (1995) reported on experimental test pods where the high-sulfur material was stockpiled
ซs-f;ซ'; ;ซ ;: * for several months before,construction of the pods. Some pods unexpectedly produced very
TOII"!!',!,*!:!1 ili;! Tjl1 " i:'l||l|K"! f, "Id,;111 iljill11 ;r||l,lf! ' JijJ'fllK 'ปi Illlll1 .rl'i:!;;,,11 ill jli'iiii;'"' .i^'Jiifli""*: l|ll|lliSl;l !'i,.."I ''i1 M1'"' |[" i; RU' .'I: ' '/I ' ,"."!*:! ":',,|i"' Vjlllh^ 'fr^llViili,,;^ rt1 ' !,|" " 111.:1' i'i:l i!f!O'niii!'ซ^ j'S ii!1:1!1" 'CIP ^iLil'SI1 1IU,;,;i,i,.M I
ii Lin i ' iif I ' in",: , , nil i *' t :> ii'l1 :ป! ii'i j I1"''"' niH 1'iiiii >'':, ,'i '"iir'! i!'{r 'ii ^ 1*1;ปi,.; *,'" u','; i li nii' :< 'II. iiwi1'" "i '3ii''' miiE^^^^^^^^ ' \ iirt;ป'id ii, 1111: 'I 'ซl >:.:'" >' rs' :w'ii ''i .iiftir";':.;: :.h SIT i m/ซ n JB : P: diniihi iiiEfip', luii
wซ|r'i^;t' :F:K ;J!:?::'" vt0$4s||iyfP'bQp Q|Ap.pO{|s may havฎ ^l0^6^ s^งn^carit acid generation to start even before the
:' i'=: '"; =: :'' ' i=; acid material was placed in pods.
i
Capping: A cap refers to an overlying low-permeability zone created through placement of
compacted, fine-grained soil material (clay), combustion byproducts (fly ash, fluidized bed
||
wastes), kiln dust, or synthetic (plastic or geotextile) fabric. The cap is significantly less
permeable (at least two orders of magnitude difference) than the surrounding material. Caps
inhibit or prevent the infiltration of water into acidic material from above.
The term liner is normally used in the context of an underlying low-permeability zone created
through placement of an earthen or synthetic material which is at least two orders of magnitude
less permeable than the surrounding units. However, materials used for liner construction can
also be used as a cap over the specially handled pod. Liners restrict or prevent the adjacent and
underlying ground water from encountering the acid-forming material. Caps and liners can also
restrict diffusion of atmospheric oxygen; a key component of acid generation.
iiniiiiii iii iiiiii in n i in i iiiiiiiii iiiiiii iniii i i i i ii i in i
A detailed study of special handling at a Montana surface coal mine included the construction of
a 3-feet-thick clay;cap> over-special handled material (Dollhopf et al., 1977a, 1977b, 1978, and
1979). Construction of the cap required several pieces of equipment, including pans and
bulldozers. Maintaining clay at optimum moisture content for maximum compaction was
difficult; water sometimes had to be added to the clay material. The region in which the mine
was located was semi-arid. Cost of special handling with the clay cap was about 1.5 times
"normal" operations due in large part to idling the dragline at certain stages of cap construction.
An experienced mining engineer was needed on-site to supervise operations and schedule
2-102
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Coal Remining BMP Guidance Manual
equipment. Special handled material was maintained in a dry state, and the investigators
concluded that capping was successful.
Synthetic plastic and geotextile "liners" are a technology borrowed from the waste management
industry. Thick, high-strength plastics of 20, 30, 40 or even 80 mil thickness can be used to
isolate acid-forming material from infiltrating precipitation and ground-water. The liners are
designed to be resistant to a wide range of leachate conditions, and are laid out in sheets with the
seams stapled or welded by heat or solvent. Synthetic liners require a smooth, firm base to avoid
puncture or stretching. The seams are a potential area of weakness and should be joined properly
to avoid leakage. The cost is high in comparison to other capping methods. Refuse piles may be
amenable to capping due to the engineered structure and controlled particle size distribution.
Meek (1994) reported that a plastic cap reduced acid load by about 70 percent compared to no
special handling and that a cap was one of the most effective treatment measures evaluated.
Caruccio and Geidel (1983) used a 20-mil liner at a 40-acre site in West Virginia as an
infiltration barrier. The acid load from two highly acidic seeps was reduced such that the liner
would pay for itself in 6 years. Because of a steep outslope, the liner only covered the flatter,
upper portion of the mined area. Recharge along the outslope area probably accounted for most
of the remaining flow to the seeps.
Earthen materials can be placed and compacted to form relatively impervious-flow barriers. Cap
thickness is frequently an issue, but a rule-of-thumb from the solid waste industry is a 2-foot
minimum. Little information, directly applied to mining, is available to determine if 2 feet is
adequate. Permeability of a cap is affected by grain size, mineralogy, and moisture content of the
earthen material, the degree of compaction, and the thickness of the lifts (lifts of 6 inches are
frequently required). Bowders and others (1994) tested mixtures of flyash, sand, and clay as
candidate hydraulic barriers in minespoil. They found that a mix of particle sizes and materials
provided the highest packing density and lowest permeability, rather than flyash alone.
Hydraulic conductivity varied about 2 orders of magnitude from 10"5 to 10'7 cm/sec over different
Geochemical Controls
2-103
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RitWUtliiH
4IP "I1 Ml I'M1 "iiiiii!:
i'i?'JJI-i!?tlf!s
L'FI ii, i I'in, i ^"iiii'iiEi*
fCoaJ_R^!nfning BMP Guidance Manual
**:iii <ฅ, :im^^^ -'fill1,,:iii!,!,;:ปiMjซ': i Ditsc ปti,..i.r> B'li'i'fc"f-i';.<;;!.:...> a-3";.ซ'ซ (!i
i'inixes and moisture contents. Rubber tired equipment or a sheepsfoot roller is required for good
,' ,1 Ill, 1,11" Illllliln mil IIIHillhiUJi. I'lllllllllllilllllillllilllllllllllllli1 1IIIIIIIII.I, l"",:ir",, I'h ,
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Coal Returning BMP Guidance Manual
Leach and Caruccio (1991) characterized backfill materials as consisting of three broad
hydrologic zones. The first zone is the vadose (unsaturated) zone or zone of high oxygen
concentration. Next is the zone of water-table fluctuation with alternately higher and lower
oxygen concentration. The final zone is saturated, with very low oxygen concentration.
Leaching experiments representing the three zones showed acid load under saturated conditions
to be about 5 percent of that produced in the unsaturated zone. They recommended that acid-
forming material should be in the saturated portion of the backfill to restrict oxidation.
Submergence has not been widely documented as a disposal technique in the Appalachian coal
fields. Perry and others (1997) found that submergence of acid material buried on the pit floor
produced very poor quality drainage at one Appalachian surface mine. In the Interior Coal Basin
of the central United States, flooding of final pits and development of a thick saturated zone
occurs on many sites. The water quality of most flooded last cut lakes is alkaline; some also
have elevated concentrations of dissolved solids and sulfate (Gibb and Evans, 1978). The
alkalinity is due to calcareous bedrock and till. A typical submergence scenario for the Interior
Coal Basin is shown in Figure 2.4. le.
Geochemical Controls
2-105
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BMP Guidance Manual
mm., ,m ., p.,, ,;, ,^.^---2.4.16: ^Schematicof Spetial H^dtingof Acid:forming Materials by the
'"'^afoM. >H< it ""'
iiiiiiiififi....!!!.,!!,:.;! I'lip1 ,. iiipwi,, '. .1 iisi! i,iiii,""!,"" :;.. 1.||ili,f.rnlll!i ", .iriiiilli,ป liiiiiiiiiiiiili1,! .IIT' ii i,''..';!, .''iiiiiii'i'i'.: . 'Th',,!!1 'i,;;'"! ' p1 ":;l.ill oil"!!.'! .' j'li....',. r:i:.! ri; !: ii., "" i1 ,,i .':,:!. mil 'vifKVii1 ii'ii.1'1,!, ,ni ..'wli::*!1 5',i, ' ii'Bi;|.l..i.,i.'.''ili'1 i"1'!if .ji..!1!,;., jiiii'lT" LI! ". '"...liii'i ...'i1: i11:'"' .. .if" iiii 't1 "i!.1... .ili iniiiiiiiiiii1'1 'iiiJiiiPiiiiii../..'.^!!11 I
!,<) Iff, CIK . , Illlf'i ["'H-JHM , 'M ill;1!" 11B1II1 ' ;., i r.,".1 ' '*'!': "" , I"i , , f ':' '-'.a.,: ...I;":,-!..:! >ป I f,^ !' V:. 'W'Jhif ,'K''.''$ IX". K;I' "i1:!1!. Mlii'i 3: 'I "i !'"' 71 '. ,!Sl TlitMIB! llffii..fill
!;iti.i^!' ii,'in,;.,* 'K!! iiiii't i\'t~',f7Xi'>i.:'-m. "His
\,;,y> n "i111"1 mil. ' in mi 'ปi :i
III!!1: "!' i "l.,li, ! liniilili :, ' ll!!!."i. I1 ,'..",::.!' '=. ill! I" III. jilli]
i". ''i:':'.. "iilllH < .lS'llli!
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SUBMERGENCE (DARK AND DEEP) TECHNIQUES
I II I I II
STEPS INVOLVED IN SPECIAL HANDLING ACID MATERIALS
i) Conduct drilling and blasting to expose acid materials,
2) Remove acid materials with a loader or dozer,
3) Construct the disposal site in the backfill at a location:
- on the mining pit floor,
- below the final water table to be developed in the post mining backfill,
- within 3 hydrologic "no flow" (very low) zone,
- out of the root zone probably at least 10-feet below the surface
4) Add alkaline material to acid material to reduce acid generation, and
5) Complete the reclamation and revegetation as quickly as possible.
Ills ,. ' H'L ," '..I, I!'11..,
Submergence in the Appalachians entails some risk. If post-mining hydrology is not correctly
il lillBl.iffli.i.lif'l.'i .ill ififil! , iiii!:!1, l' " :', 'ii,. Will! illllllllU .illlillllllj '111!.:;;" 'IM111: J".,!!::,,."P.1 ',"i'll|,.li' ! I*!!!,...ili " f ^ !!' I: ,:,!!j Ili'li r iiiii.'"'!! ..ifi1'11'!:".' Kill!; ".rivjl11! "lirdinl .1.1. iiillilli!:ii|ii.:i!.:!: 'I' .il'.....!:!!.!!. III. i" I1.',,'""Mil.!..:,:; 1 1" .!.'. .. ' MIIIII .:, '.1.1!..I II. I:!'! !|I:!:..!,IIHI|I! ."mill , vl,'! IIII
BK !;< 1,,1'f 'ii!:i: ^rs.'i'iE^ may,^? gener^ed- Weathering products are leached or
|;| :'.' ^I'mpbilizel by flowing ground water. Therefore, it is imperative that the site hydrology be well
jlllll (^Idj !')| i|il|l| ''' j '*' '": .{jiif:1 tfiii!1'!11! xif,'f fiiiiXi:' HM\ !.'ป'."" ii" i * Sftitif Jiiir "iiiiE c" i! J .,"1: nป "': > .iiii'11'*1 iiii'11!!, i; i-, T . IE, if ijf >i, jH'iJi ,J J! .liE1, li^liilliinUrl t '' A1 ii'iEi;' i I ii' ;'i,..' "f- iS1' siiiiiS;. ;,''* i i;i ' ii li1'. 'f> t ifm i vttXr'^ i' ill
.;;;;; J'';].;';; ' -Vlfifiiderstood^ Information^ecessary to characterize the ground-water flow system includes:
111:'!,". hi, .an1, i ml!
HiHi"1,!,',,!1, M.h,1.liป 'ii;':;:'1!!'!!:;;;:! 'u|.
!! if11! " "'!:?.. I1"!,!':,1!1'!"
"'L*:' "" "''''"' '""*1 :m Estimates of ground:water recharge to ensure a pg^^^ ^ sufficiently thick" water table.
'" I!1 "" "
:: * Determination of how isolated the site is hydrologically from adjacent ground-water systems.
lliiilEiiJ111 i lil'1! '"''''"Lli'l11 ii1''''.''"' IIIIFii 'iJpiiih'i 'HI ;'il!i:,i,|iiii'i'li'!i 'lihB f "'"',.. 11:!.1'1"! '. JiiiJ..' ' wiiii'll '!i. ''i'?ง' '' "i|11 |ll"'!li|1; i:"i VI'iMiv,.,'1.11!!1'!' 'ii^1;iliii\!t:i^l\lFi^ ah ..IliJIS i^ !,!|!' 'l^'M"^'!'''''^'^^,, "-
^^^^^^^ ' I,,,,!1 :": ff.il n 'K.l " III -" '' ' -.JL-'J.1. . .' .' ;.. " -. "_;_.. .... _...:....;._,__:_.___.,__
: - -z "'.:-: .. -. ..2-106
Geochemical Controls
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t-i ill .. iii'-i'"!.:!*-!!!1
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Coal Remining BMP Guidance Manual
Determination of whether the backfill can be constructed to produce a reservoir that will keep
the acid-forming material continually submerged.
This type of disposal during the mining operation should involve handling the acid-forming
material only one time before permanent placement (such as on the pit floor of a previously
excavated pit).
A possible disadvantage of submergence is that pyrite oxidation may have already begun before
the material is submerged, forming ferric-sulfate salts. This can occur during storage and while
the water table is rebounding. Upon dissolution, these salts release ferric iron that can oxidize
pyrite and sustain acid generation in the absence of atmospheric oxygen. If material handling is
unsuccessful (i.e., the water table is not stagnant or thick enough), resultant drainage problems
can be large scale. This technique might require a relatively long lag time before success/failure
can be determined and large areas can be impacted before the results are known.
Handling of Acid and Alkaline Materials Using Blending Techniques and Alkaline
Redistribution
Blending is the mixing of rocks on a mine site to promote the generation of alkaline drainage.
The term "blending" has been used widely in the past to refer to the mixing that occurs during the
routine mining process. This technique has been recognized since at least the mid 1970s.
Anecdotal information exists to suggest that it is an effective practice. It can be effective if
sufficient carbonates are present and can maximize the contribution of carbonates by mixing
them with acid-forming rock. This can inhibit oxidation of pyrite as well as neutralize acidity.
In theory, it is possible to blend rocks from virtually any position in the overburden column, but
the actual practice is dependent on the mining method and spoil handling equipment.
A spoil mixing experiment with dragline mining was conducted in Montana where saline or
"toxic" overburden was present in varying amounts across a mined area (Dollhopf et al., 1977a,
1977b, 1978, and 1979). Premining distribution and properties of the toxic material were
Geochemical Controls
2-107
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IFlliflifii !
r .irtliif'1*,,' jfi , ฐi|
:^,1^J= :=,CoalRemining BMP Guidance Manual
from overburden analyses. Systematic drilling and sampling of the reclaimed spoil
after mining showed:
I I; Hi I., l in"!'!'" . liillilill|.j'-i-l Us. 'll'i::,:1',:)' Ill >. ' ' , .j in,r j i , ... i, , , ป., i 11
ip wf " ;;: ill;" |Jป..flf'1 IS- w^",';. >:: -iii -I: I "i:; i <- vi i; i; ' * jlii Ht'i1:; iW'jip' i A; KHi -M J> ^"' 'f *ป
"i" S;** : ' *" " Wlien me toxic material constituted about 5 percent or less of the overburden, the material
ll I
11 , 'f! ' , IWI < - ป '!,' llhJIHI' ปl
III!'1 ,,,J lilllill 1 Stiiilli.rll' 'iill -
'ii; ,iii j1 11' uซii:i: ii,'<' ""' >f> *n, ^ i; iii' ! r B : ','<; -\ mi1 Bin .., in; ,1!' <. :[i ; n'': ,1 Bin1 MB;, B1 r1 IIBI Bin'' IIVBIBIIBBI| ' n it iBBiiniJiit inn1 ,iJl ivป ', mm in: ,i n s; "i1 '<,: MI;;"!' t ,'ป '"':
jljlljljl B''"B,11 Bii.BlJBi'i,,!!,;!'!1' .iil'iii'l'llllllllllllllll'n.-BlilllllllllllBMilBfB11 i MBit Mil If',, 'I'li'llIBB iJil,11'1!! , i BBi't!'" ii,"B"i;l'',! ,.: ' '' I'r'Bill1''! ll'ป it i <> n , I1 iiinKIII ""l1IIB|l;llll!!'"1iilBll,li!l1 < Bl Illlll! Jfl'li" 'Bill 'ililBIIB J'^illllIllllillilHIl'':!!!,;''''!!!''11 V'.IV, >,i,l BiBIIIIIIIIIIIIBlM , IBHV,11 n'lBB ' ' Ci
Jite ^importation of alkaline materials ^alkaline addition), the portions of the site lacking
ii'WniBBi,, ''iiBiiBB11 vv: I
i; i, ,f iC: III 'i l|:, I* UK i1'!'
^SSals will produce acidic mine drainage. Examples of sites where alkaline
n,i;4 -HIIIM,,,. ,n, luiiiniiii' '.'aiii'ijiiitji, ,"", :,i,,,ii ininiiLi iiini,, I.F': imi1 ; , '. ij":1 !>'.ii hiui ;j < \iii.iiiiiail !,:, :>i.iii min;i M ; ".i,.iiiiiปii..nii i-n,:'ซ ii if .i ii'r,:, vi> ".iiiiii :; )i lit' r1 uRi iiiii; ', ,-'t i"i,:, v >j:t* m i niif IIDU, - lit" innii't .1 , ni";: i '< in",
Areal distribution of alkaline materials,
: Position of alkaline materials within the overburden section,
Volume present at the mine site, and
'^'Fl ปii iiii"! ". >
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Coal Remining BMP Guidance Manual
Location and available volume of alkaline material largely determine the feasibility and
effectiveness of alkaline redistribution. If the material is present as a discrete identifiable unit, it
can be moved as such. However, if the alkaline material is laterally discontinuous, or dispersed
through the column, a plan to isolate and move this material will be difficult to implement.
Alkaline redistribution strategies can include:
Determining the proportions of alkaline material to be placed on the pit floor, mixed into the
spoil, and added to the spoil/soil interface,
Determining the methods for incorporating the alkaline material into the backfill,
Choosing the best pit orientation to minimize haulage of the alkaline material,
Designing a multiple pit operation to facilitate redistribution of alkaline material, and
Ripping the pit floor to expose alkaline material (when present) beneath the coal. ,
Actual implementation of alkaline redistribution generally requires the use of rock trucks, since
the alkaline amendment is not an integral part of coal overburden removal. The amount of
alkaline amendment per acre is calculated via overburden analysis and mass balance equations.
Operational Considerations
When special handling is part of the mine plan, keeping the pit clean (e.g., removing pit
cleanings) and quickly covering acid-forming strata are simple and important activities to reduce
the potential for acid production. Removing pit cleanings, will ensure that any ground water that
reaches the pit floor will encounter reduced amounts of potentially acid-forming material.
Equipment availability is an important consideration in the development of the special handling
plan. If the proposal is to move discrete rock units, a truck-shovel operation may be necessary.
In addition, if two pits are open at once, a truck-shovel operation facilitates the movement of
overburden from one pit to another. However, if large sections of strata are to be removed, a
skilled dragline operator may be required.
Geochemical Controls
2-109
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If"
, Coal Remining BMP Guidance Manual
If an alkaline stratum lies adjacent to a potentially acid-forming stratum, the strata may become
mixed without additional effort during the overburden removal operation, and separation of the
i
potentially acid-forming strata may not be needed.
' 'iiiim^fiti;> m&sw;":...>S;A "i:.i/i' ฅ':";''m^AmM^^l h;";:
l!ป :' "Generally an excess of neutralizes dispersed throughout the overburden profile is necessary to
offset both acid production and imprecise mixing. A simple blending plan is shown in Figure
," .iir, u',,;,,' 0 A If
' niqi'f'^i " .i i iiT&.-r.A.l.
I ill ilii. Rni,'1!!,!,!'1'! : ill1 p.:!!!!1'
.|.!',|iJ!IIIIH i 'I1'*'"'!'"'!!!!!! ill! 11
I'" i"l',,', !''i,!. i . ' i"* "I! "'"IS,"
'iJilrtnllt li'iSnliiii.i'iiiifliP'i'!!,11! '.! '!;, IIIHO'Liilil'ii1'1! ,.
Figure 2.4.1f: Blending and Alkaline Redistribution Do Not Require the Isolation of
ill ll!l.i I1" TlliL,'',!". I1 "ซ' Ill
:,ซ i- 'iiii ,i Acid-forming Materials in Isolated Pods
Hi "III!1!!1' ,)l!:i-:!'' f!'.;! ,>
'I!']!, !!if ll;l "I'iii: '::::""VHl!!"!" iiii1 t '" '.:*'.. '" , -i 'SB 'f TO.' ""'I "' *H '.'' .(i S!;-* '>>">:ป V' i.O!i!i! I'lK ฅ.ฅ', ."if- ป : 4iJHJfti;. ili'SJitl l. -llifWlliii: . >:; 'ill:1, (Hf. ilii1,, ', I'.ill!!'! '1HM -iilllll I
inlllllfliiii ihllllliR ilh'U'1!: '> , I iir! i I"" '. "".i f. linn.
ipi iWJiii'.' liiJIilii'nlllllill!' a I.. .1 ilii i ;, |i< ' :,"ป ,,;i:i,";,;,
ijii'"'iiiiiin 'ii ' i* : ; ','i"i!1',,.', ,'" ' ,,i'
MI,:' ;!',' ' Fi'*" :i"fi ; ,,"ii: ' MI
'.fll!1,,"!1"!!,";:"! ..11;1; :,:': [ iiB" ;' ,i' | '" .', n,,!,, ,.,"; ' j'Tfl;i ,, ,,, "JiirLr,: I,'11],1! J,!,;,,!! iK,'1 Ml1 'Ib,LlilllllllK Lllllli: .'c""'i,!!l'i! I
f.;!ji 4'll;f;"Ji:n. 'iii: ',*:!
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i!hfclii;|:;l:!l:l4Kli^i5;ฃ:
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BLENDING AND ALKALINE REDISTRIBUTION TECHNIQUES
lliiiil 1 11 Hi1 I
STEPS INVOLVED IN SPECIAL HANDLING ACID AND ALKALINE MATERIALS .
1} Conduct dn'ijing and blasting to expose acid and alkaline materials,
2) Remove acid and alkaline materials with a loader or dozer,
3) Blend (mix thoroughly) the add and alkaline materials, and
4) Complete the reclamation and revegetation as quickly as possible.
i'l'l '" nfj I'I
'I II I (I ,11 "111
2-110
Geochemical Controls
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Coal Remining BMP Guidance Manual
2.4.2 Verification of Success or Failure
A critical step in successful special handling is to ensure that the special handling plan is
properly implemented. It may be necessary to periodically perform additional testing of the
overburden to assure that the proper material is being handled.
Inspections by the regulatory agency, of sites with special handling as a BMP, should be frequent
and detailed enough to document compliance with the mining plan. An inspection
implementation checklist identifying key aspects of the plan will be useful.
Implementation Checklist
Recommended items to be considered during the permit review process include:
The overburden data should be sufficient enough to identify which strata will require
handling.
The overburden data should be sufficient enough to provide representative sampling for the
mine. This will typically require multiple bore holes and appropriate vertical sampling.
Plans should be clearly designed with appropriate maps, cross-sections and narrative.
Plans should be feasible in the field and not just on paper. For example, the strata to be
special handled should be easily identifiable in the field.
The plan should be enforceable.
Recommended items to consider in a special handling implementation inspection checklist
include:
Field implementation should correspond with the plans in the permit application (e.g,
agreement with the permit maps, cross-sections and narrative)
The appropriate equipment should be available.
The blasting method should be appropriate.
Geochemical Controls
2-111
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Coal Remining BMP Guidance Manual
The material to be special handled should be identifiable in the field by the equipment
operators.
The water monitoring data should be submitted.
I 111 III -I , :!" II ( I III
2.4.3 Case Studies
Case Stud 1
;i Cravpjta M^ ,,0|hers (I994b) compared the distribution of sulfur and neutralization potential in
;;; ..... ...... undistarbed overburden^ strata (Figure 2.4.4a)A\dth the post-mimng redistributipn of these I
Jill Kfil'l'; ' , !ซ i/j
mm 'ซ"'
'ป)' ป"." |J' ill"!::,if
__
3 disaggregated mine spoil (Figures 2.4.4b and 2.4.4c) for two mining methods.
ua**M!l. K; i n '!:!. :, "Ijfl,!;,, li'dlililiM^^^^^^ 'ป f-j'"!, Ill i.BlM , 'Iiif. ^illlnln]A , 'illllll i Sill!": .'iU'l'lifi't
(as a reclaimed surface mine on two adjoining hilltops in Clarion County,
Is ill!' 'i1!!'": i .: -IS:: If * iiiii: i "S; I:' I ;1it '-ii* ' \ (i',ซ. is "Sit iป ป i- ; -1!? SB!!! :"'' !', 'Si!'si: BI }i i ; j,i! na-,, ii latiiti1'';,:. i! ;:'. ',1 i'liK: ; h i i' ,;,j ^mxi5.;tfm>
Pennsylvania. The southern area was mined with a 45 yd3 dragline. The northern area was
mined with bulldozers and front-end loaders, which selectively handled the high-sulfur strata
near the coal.
aim /iiii-ivi nine;.
liปlll.ii Kill' ,t-A, '::' '" 'MEIIIII!', ! IIW . !' lull: ) '' '" ,:!
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Coal Remining BMP Guidance Manual
Figure 2.4.3a:
Distribution of Sulfur and Neutralization Potential for Bedrock at the
Special Handling Site in Clarion County, PA. (Drill logs are to scale.
Most sample intervals for Nl-0 are five feet.)
Geochemical Controls
2-113
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n
;ซ; ''. : |;; g Cffa.L&iimw&g BMP Guidance Manual
Mf- ซ3fi" iiii :,;!''' jjjjjiii lil'M'lilplJWWBfttn*;!:'&*ฃ'?'*WSMi'. -il I'i"fi.V!ซ*l!,,; [lit!/'!'.V!' ilซ ,Hl!i: I* ifflSAli 3 Kf,liii'li :5Iiiiซj;:: M& ('''(SISfeBf* it
=;e.;5PginJ!lJRl!?1 fpJ-.Qz. 16-acre northern area called for placing the high-sulfur rock in pods 10
* feetaboye&ฃjgit floor, with low-sulfur material placed between the pods and the pit floor. Drill
"lit,11,Jill niiliiiijil,fill1 !'i ' IlliiiflJIlL .iilY" i'llllllllliNlli ''''ii'MTillilillllllllllllillllllliiiiiiillllliJEIIIIjllllfil' i,'ซlijiB i VM' ':|Ji''iHiKiiilH'.*!!1 . '! "ซ!'" , "UT" i>"| ,vi,, ,|i||" !|| PITS'1 Illiiiwlii1"!:. ,, ,i "":ซ ,; ' ' Jiff,ill!ซ,,ill'Bliifi,'JMIIL ^itHUIIIIiillll'JIil*'," i|ป', BBiii||il',1,1 ,;i,i',! ,'! I""i,,: ; IWiBIKIFIBI, ',; '1 1'Flj1: >' WB, aUilW''!.'^!
r ;!-i:: ,,:i":,; EtlftL?iง,i6t?-fl iPii N2-2, located 5 feet apart, encountered one of the specially handled pods. The
i"t "IIJ! .';;:; .":*:,i!^^.^!^??,^0^ ^l^,^11!11^'in ,S,enei:a!' inverted,the high-sulfur (>0.5 percent) material and I
;-;; ~~ : ?;;; ;" = lpcatฎd it nearjhe^ spoil surface. i Most logs show low-sulfur (<0.15 percent) material near the pit
I!"J| I, SEI" '.( i;;ii||, '!.;, ||iiiii|i viiini i,iffff', '; _ , -Kr' !:'.; .IJ1: 1,1,:. Mik IBB ,',; :l!l1 "'ป:";,".,! l:;isfflin. i' . '
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Coal Remining BMP Guidance Manual
Figure 2.4.3b:
Distribution of Sulfur and Neutralization Potential for Spoil in the
Northern Hilltop Where Bulldozers and Loaders Were Used (Note the
"pod" of selectively handled high sulfur material in N2-0 and N2-2.
Sample interals are five feet.)
N3-2
a 10
D.19
0.54
a.so
0.58
N3-0
2,00
4.QD
10.30
1Z.OO
9.30
0.03
0.28
0,87
U./6
Q.63
1.25
1.4C
0.08
0.08
0.07
O.H
0,05
O.C2
U.U6
M2-2
N4-Q
= 10,00
i 10.00
0.49
0,48
0.19
C.55
0>*3
0.02
0.04
0.04
C,14
0,5*
0.03
O.D2
0.02
4.00
1,00
5.00
*.OQ
6.00
3.00
3.00
3.00
a oo
7,3]
3,00
ฃ.00
100
Geochemical Controls
2-115
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2.4.3c: Distribution of Sulfur and JNeutraJizatipn Potential foivSpoil in the
:v'" (^'^M:':''t1ioutherii Hilltop Where a Dragline was Used (Sample intervals are five
':";:;: "::';"' ' ';::'" " feet.)
< : "liillllt' "'ill , I!:1"" I1
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0.25
0.23
0.2?
n 27
13.03
1
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Coal Remining BMP Guidance Manual
Case Study 2 (West Virginia)
Skousen and Larew (1994) describe the redistribution of alkaline material from separate but
adjacent mine sites. Calcareous rock was hauled from a mine extracting Bakerstown coal to a
mine on the upper Freeport coal. Alkaline redistribution consisted of placement of about 3 feet
of calcareous shale on the pit floor, partial backfilling, then placement of acidic material about 20
feet high in the spoil, followed by capping with more calcareous shale. A pre-existing, mildly
acidic discharge (acidity about 75 mg/L CaCO3) was ameliorated and made alkaline.
Case Study 3 (Clearfield Co., PA)
A cementitious cap constructed of fluidized bed combustion (FBC) ash mixed with waste lime
has been placed on a 97 acre reclaimed mine site in Clearfield County, Pennsylvania. Hellier
(1998) reports on the successful efforts of the operator. Surface mining on the lower and
middle Kittanning coal seams began in the 1940s on this site. Upon completion of the mining in
1991, the operator was required to pump and treat an acidic post-mining discharge. Treatment
costs threatened to bankrupt the operator. Most of the mining'on the site predated special
handling techniques. The operator removed the top 3 feet of material and spread a 3-feet layer of
FBC ash mixed with 10 percent waste lime. Water was added to increase the moisture content.
The ash/lime mixture hardened to form a low-strength cement. The top material was then
replaced and revegetated. The cap served to inhibit infiltration, which was thought to be the
primary source of water at this site. The cap would also inhibit oxygen from entering the
backfill. At 80 percent completion, the operator no longer has to provide chemical treatment,
pumps significantly less water, and the chemistry of the water remaining in the backfill has
improved. A passive treatment system, which is in place, is adequate to mitigate the reduced
flows of AMD.
Geochemical Controls
2-117
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Coal Remining BMP Guidance Manual
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Case Study 4 (Green Co., PA)
^A minein Greene County, Pennsylvania produced both alkaline and acid water on two segment
i:Litฃiilง li^Kjphases (Perry and others, 1997). The two segments had similar geology and hydrology, and were
ilfttiii'fiifli; ''^':; JK.hpRgfllJpy..^fฎ Carrie company. Alkaline drainage was produced on the segment where mining was
It; if
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ii;, completed without stoppage and where a special-handling plan was followed. Acidic drainage
If i'If'i'lIt <<.!.; 'if ii w SJB -, ?ซ m m :?;m# ',;i !ง,;;: i^ m w$ >f TM IB^^^ > .:*.*ii:i!;. 'ซ!,/ fR&$,''I;l:i?!|ซ '-:'i;;l:i 11*!? t:'iff;!ilii'liii'if i||;,.:$, i Slj'lli J: " '"SI'lilir'11!-;!,i Jtiiililr'i, < '' if!' WfPilll': 'If-' 31 \
jigM^f^m :[;:-if ปK^iWM:^|Ppietely reclaimed. ^ The poor quality drainage on the Phase 2 segment was attributed
jf^ivKitQ feathering of partly reclaimed material during mining cessation and poor adherence to the
i MiiiE! ii,!1',, iniiiiJiiiHi '., inn , i,,,,;:, A; iii; iir, 11 v, ,iปiii;aiiiiiia;i:"!!, "'Hiiiiiii' i ,<':;'"' i^iir.^::!! jciwMHir nvi,'am ' ^iri1 , n:: i ;v ::ii i T ' ;, MI < a-;!1 ,! " <"', s ,11ฐ"!' ! nK ll1"1!,1"1 : inii :ii1'!1'!^" i kiiaEiijMn^ flijjiaiii'aaii'iiiiiii:1" ijiiiiiiJai'i''^!!'-!!!1,:11,!! liijii'111!,:,1';!1!", <;ii '.i'1!!!!':1, laiiiiiiiiiiiinaiiiii'jiiiiiiiiiiiiiiiiiiiiiiiiiiii
affi;, ty, ^j:.ซ pjiieฃial handling plan. Median water quality data for the two sites is summarized in Table 2.4.4a.
KM,1 Jii'l' "JIM1!",',!!
;|i;|;Tab|ej2,^.3a: (, , Summary^ Water Quality for Greene County Site Phases 1 and 2
Monitoring Point
Phase 1, Mining
Phase 2, Mining
Phase 1, Post Mining
Phase 2, Post Mining
PH
6.5
3.6
7.2
4.0
Net Alkalinity
(mg/L CaCOS Eq.)
176
-488
151
-128
Total Fe
(mg/L)
0.3
71.4
1.88
18.7
Total Mn
(mg/L)
6.5
105
16.35
62.7
Sulfate
(mg/L)
606
2233
1197
1770
Case Study 5 (Westmoreland Co., PA)
A mine in Westmoreland County, Pennsylvania used alkaline redistribution to amend a portion
i
of the site that was deficient in carbonate-bearing rocks. Acid-forming materials were lateral!
1 tlllEI") iiti;: "IE: ill i,; !:ff' ; Ml "X, :!: ! 1 1:: ' lflปM(!i'1fi; SKWPH W.ft! :/ Ii :f" ^': ii.''.'ป KWW "*" ' Ji: ' \ ' 'f. ii < ^ K,!K* f lit 57 ';:' ' ,i,/:" ; iriS'l' - '!: ' "''ป 'I
i
I
::,! :';;:r:,;;j,;;:::; :, K^nj^ugu^yin^ hM^Sjo^ovei^ percent total sulfur. A zone of calcareous materials, with
iliil'llii*'1, '! !!i| -. j";, jjjii |.i: i' \ fm iii ^"<,' iiliiii; \'M " mSiK \Mti ii '*? i ;-j: ft;;ii * 1. f i s t t fLi M ii. as'i li'iilliiiiil!;!! 'lilfy^''.! ฃ ปiปi if \"<ฅiMW & ^i5& v. irfli ','f i'ail f ilii lifii' ; i; :,i I
= carbonate^conten^ exceeding 20 percent, was present over a small area of the site. Special
iandling consisted of moving excess calcareous strata from the upper end of the mine and
:Jllliiiiiiili, I'lii'iJi'j'Uiii, ll WiiK ::i '' IlililiiiiliiHl!" fikiiiHiiii'ii, i i1 Liaa.aiiaiiaaiiaa iiiaiaiiiniT ,,. aia!!"1!!1 jnv.",:"!1';11!^1!: 'lUj iiiiiiiiaiiiia.,; : , na. . aia;1" ii '"'in,a '"n ii1- '. ii1::1ซ.a .,iii|i,aiiia,iaiiia,aiiia"i!,!iii1!11 Miaaiiiiia iiHirii1 v .ซ ..i.iaiiai.i i m/i'i'iir.!!.!!'!*! .wi",1'1 aaiaa;,!.1"1 aai - "'.".i ' ;'
jiiiiiiiii.i,i: iii;Ei:ii ii1 iv|" lindii ii < niana a. a11 'i.an1 i -,:ซ.;iซaa< i. a''iiiiHi''11 ! innuii: ! .<;."i; t <ซi|<'":|i!'<:. flf11ii4.ซ.|:i|1"1'" " UK> "aAM # <"< ihi...ซ Li' -. ""<> ' ivป, .J'1 <'. t i a"' :, i ',a ?>*,:': i .<ซa1 ana;:i i.1 IIIL 'iaiiiainiii1 .a.:jainiiKi1;; J| ;u.i,.'. aiIIN "|f ii,;'ix i^,\t aa; ilia111:!: ''a: i,<!a ,>ป <. i11:1 r iaiiI,L '
lK Sl^'IR ''i.:' RiSSJistrib utmg itiri'the alkaline deficient' areas. ""Three"pits were "operated'simultaneously.
-Operations^were: timed so alkaline material was available and cut and fill balances could be
S5'iป "ttS1 ijiiiiiit ! T.. EMiMfltai.n,eji MiterM, placement and backfilling included crushed limestone on the pit floor,
iaฃ!eo(:hfemi(;al Control,^
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Coal Remining BMP Guidance Manual
"neutral" spoil backfill, placement of potentially acid material in lifts covered by more "neutral"
spoil, and finally topsoil.
Wells and springs have been monitored for four years after reclamation at the alkaline
redistribution site (Table 2.4.4b). In Well MW-6 (located downgradient of the site), median
sulfate concentration decreased by approximately 70 percent, and net alkalinity rose above zero
after reclamation was completed. MP-10 (a spring located downgradient of the mine) is
representative of shallow ground-water conditions and contains negligible alkalinity.
Overburden rocks in the recharge area for MP-10 and well MW-6 were likely acid forming.
Post-mining water quality for MP-10 and MW-6 show a small but significant increase in net
alkalinity. Sulfate concentrations indicate a lesser amount of oxidation and leaching is
continuing within the spoil.
Table 2.4.3b: Summary of Water Quality Conditions, Alkaline Redistribution Site
Monitoring Point
MW-6, Mining
MW-6, Post Mining
MP-10, Mining
MP-10, Post Mining
pH
6.1
6.1
6.5
7.1
Net Alkalinity
(mg/L CaCOS Eq.)
-8
24
6
20
Specific
Conductance
(umhos/cm)
855
404
N/A
280
Sulfate
(mg/L)
398-
115
19.5
90
Total Fe
(mg/L)
0.15
1.5
0.04
0.09
Key factors influencing post-mining water quality are the redistribution of calcareous rock to
alkaline-deficient areas, and rapid completion of mining and reclamation. Responses in water
chemistry are attributed to placement of acid-forming materials above the water table to
minimi.ze leaching, while the calcareous rocks are dissolving and producing alkalinity.
Geochemical Controls
2-119
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i in 11 in i in ill
I'll'li'l11(11 111 (I11!11
i BMP Guidance Manual
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Case Study 6 (EPA Remining Database, PA(10))
(if | til pi' ..... i:i Jit
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..The PA0J^ is ^so (tocussed in Section 1.1.4, Case Study 3. This site included the following
"mm: . '. ..... H!fS":ป' ::iii' i ..... tiM:ifci?iii*#iH I- 1 ; ...... ** 11 ..... i ...... i;,/ ..... i ..... . \ i;a \: ...... ! i iiir? ..... K; .1 ..... ti(. jut * ..... ^^t, n ..... '\t,mi;: , ...... tm> , ; > - ...... t ::; ..... .' mij
BMPs; regrading of abandoned spoil, alkaline addition, hydrologic controls, revegetation and
li !" ........ i'.jfflfli' r |IB .iii**!!.!! ........ ''I'lifi ...... 11, ปซmi <.: i-i .,.;* 'if ,:,ป", ..... ,1, i , ' ,11 KIIII, 'ซ ซ! ..... iiir" .~i :ii. ...... !&ซ> ....... ..... ' . ,..ป ';ซ '111;' -1 ": ........ :1,1' :;,,
calqarequs. pavement, and application of bactericides. The only calcareous
.th.vin(:ei:qay beneath the lowest coal seam. There was a significant amount of high
^^ mi1;; ...... wi* ill i *. .............. ; .......... ,ป, . ;. ;,,4 . & ..... I ...... ....................... ...... \ - ......... ,
. ..... rf^frs ...... ?Pffi ..... fes^viltt'^^ ..... &g ..... cpai ....... ..... ...... , ......... _ ........... , ................
', , ;' jlli j, -l | ' v i ' jyjf : ; lirliil i;i jiliiji ' Sii 1 ......... S ' tiii ....... 'ii:' 1 Isii? y : &* A t! isi; ' t ,.,', i W i: 1 S :. i: ' -h iili'l ..... 4 iifiirim * Iliie1 -,.. iimlii1" : iiii Iiซi ...... iid;1 >. .; jiiiilil:; ..... 1 . . iSi -i1 lit&.ฃ.ifK. iSii:
^company proposed scarifying the pit floor (to expose the calcareous underclay) and a negligible
, : ;; : lil " i ~ * ;-: IN ...... i'!;.i;W sill S i! , f'C'ii .;$< ..... ^ IPS ^/.j*^1 c >;! i^k1- ;' ;-"' t M? * m^ ..... mm ...... ii'JiiK ;t^i .......... is ..... i ....... rtiiif>r,:i ' i wnur !i nw ....... ITM ......... ..... ...... -i .................... t v ............. ..... .
' >'rji": IMkaline .addition .rate ,pf 3 tons/acre (applied to the spoil surface). Bactericide was added to
'^'''I'WMiili!!:::.!!!* ..... ip^if Kfi4S,il!i,.lf'iii')i.] ..... '-Ml ....... ifsitia^ ^K-^i'.'m.i'jiitmiiimaHi ......
F>reVeht oxidation of pyrite through the retardation of the pyrite-oxidizing bacteria. Scarifying of
" ...... i' '' ..... ,H'" :;.'"',: ' ..... iniir ....... :i ..... f ........... '^ ..... > ,i f ,,HI .................. .'". , I1 ;,;'<. ' iiilllliiilli Jill11 .;l!:'* ;'.!.. ' ;..tt ...... SIT. ' .......... I > .ii: " . ; : jl ,. 'i '!' : ".," ' 1 rj ....... l! :,""!'"-!; 'tXili: ...... . .[.jKi1 >J*/t'i!p ff.nti ...... :ปj1U..,M ..... ',, It'll ...... .!',,. JilHI! ..... 'i.'SiHMBHU^Ml'iiB
.. .. Bir 'I ......... :. i;- .:;i.:;!' ..... "^m ' ' ill ...... ill; ..... [.! .t ^iiW.'it ...... SI f ซ"l!::i,; ;' 'rf'M : :,: ., f i . , !' SM't ..... it: m,^ ii ..... Si ..... it,:;"1 5' ,-Js ........ ': ll'li! ...... &..,-.MWX' ....... ?;YK ..... 5 v ..... SiiXifii ..... W'S
fiji?^!!^^ ....... one of gnly a handful of renaming sites in Pennsylvania that have resulted in poorer
i, I, , :' t ;, !<,!'' /i' xmt-'1 ' Jlillll ,: "t,< 'l iiii ..... ', ...... .' ; ..... ,,- i ', ..... i,' .......... '>;:>, > / 1 ...... 'f> ..... T , >: ' ...... ; ,. i ... /in, ,,,, ......... ' ................. (,, , i,c,'>,!"!i i ....................... : ............... ......... < ; .......... , .............. , ................... t, ' ' , ......... ' ......... , ...... ,m, ...... ซ:!, ................ ซ ....... r .............. ......................... ....... ...................... .
jpbst-rnining water quality (see Section 1 . 1 .4, Case Study 3). Several factors may have worked
together to contribute to poor water quality. Failures have been observed at other, non-remining
,; :;;|sites, where ...... the bujjc gf ^e^aUne material, was located ,,,on ..... the pit floor (Smitli and Brady,
1998). Scarifying may not have broken the rock sufficiently to allow for exposure of adequate
surface area of the calcareous strata. Perhaps this plan would have been more successful if the
calcareous material had mixed through the spoil.
2.4.4 Discussion
nlEr'i ' ' 711, ,!.'!,.!'. IIH 1 I" Ki i'
!',, I !'!! ' i ,i !1 VUiil ,' " 'liihillllllllliill! I: ,
il''! MB ป' ' 1 " ", T! lii ป,: ' '
: ,, ': "iii1" : ' f '! > ': . . I tB, ..... , . It "I
............... ,, ,, , , , . , , ,,, . ., , ,. - , . , , ,, , , , ,, . , , , , ป .
Despite years of implementation, few studies of special handling and its effect on post-mining
li!' 'I ' ' '< If!!1!1 '' '!< ^"iiiiii!!1 '< in !' ' lii!!! iif ' ' if i': "i<< 1' I*! "i i!'!l'i< '!' liiii"'1'' 'y ||i'|i ' ' " * s* Tl l!| ^ "llii!T "lii! ..... h >|! ! ' ;>l:<'< '^ ป V| ^ ' ' |Ji1 :! ป '! ' ||; ..... :|l"< j " ป< ป:' "|i|?|l|"Jii"ซ ' |||! '' ;| ' ;| J|; ' ' ..... :i|||;l '" r : " J> " timto 'Si ii;[ iii'iiiiiiP f!:' ..... i:'1" I'tiii , i j, aaai iiiifi ...... i: . ' <ซ \i\\\ \a rit i iiin i1 n : i : ifiii ^ 'stc WA "Mf , ..... st ; : nn i
water quality have been performed. Special handling is almost always used in conjunction with
Iltallill, I ......... V'iRI ..... ;!': t : illilii .ill, ...... ,,~ !", ',; ...... , ..... !;, ..... ' 'ill 11II1I''< ,' ' ,||III1|111 , Uil" '' ' il>!" ...... I, : 'Ii ...... ,")< ........... , j'llili1 ..... Rll *:, ,.!' 'I'1:} '!' I:':' "I >' i"; 'I'l'1!*!,' j, 1 ....... 1 !,i! i SSI ...... I'1 'l!EIK::,il! .IlllBIK^^^^^^^^ ..... ' flllllilill,,', I1!1:1 ,'';> iii'l'Mli1!!!! ..... ..... jk: IIIWII: !!l 'nil ...... IIIIIIU,' ', ..... ......... ...... ! '','!",
other BMPs, thus separation of the effects of special handling alone is often not possible. For
sites lacking calcareous strata, special handling alone will not create alkaline water. For this
......... ............. ............... ' ...................... ......................................... " '' [[[ ................. If .................................... ................
reason, special handling is ...... often combined ...... with alkaline ..... addition., , For_a jite to be, a ..... remining
....... IP, ...... ft^lte6!1 Pf!eYiฐU!?ly.
by mining. This previous mining and the type
1 ,ป iiiiitii ..... w Jii^^iiiifiiiii"''1.!^ .i/iv''^!!!!!!!''!''^'''''!,'! "iiii" ...... iiii:iiiihii.|'ii, ./''ii viiiiiiiwiiiiiir ivii' iriiiiiiiiii'.,; "i. i' hi'vi mi iv i;iiiiiiiii::ii
ฃ':;^'1;.;;:5:ri:|;"; " 2f sssociated^rejmning is of -three types: deep mining and subsequent daylighting, strip mining
i mi iv i;iiiiiiiii::iiiii;iii, inn ru
and subs"equ"eriฃ regrading and revegetation, and coal refuse removal and subsequent regrading
2-120
Geochemical Controls
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Coal Remining BMP Guidance Manual
and re vegetation. Thus remining sites with special handling do not occur without one of these
additional BMPs.
Special handling methods fall into four categories: 1) blending, 2) high and dry, 3) dark and
deep, and 4) alkaline redistribution. Blending is generally used where both calcareous and acid-
producing rocks occur within the stratigraphic column. Mining is done in such a way as to blend
the two materials together such that AMD should be prevented. "High and dry" and "dark and
deep" are intended to limit the amount of water and oxygen in contact with the special handled
material, respectively. Limitation of water will be most effectively accomplished if the surface
of the special handled pod is sloped to achieve ground-water runoff, the pod is capped with a low
permeability material, and the material is placed above the post-mining water table ("high and
dry"). Limitation of oxygen can probably only realistically be achieved by submergence below
the water table ("dark and deep"). Alkaline redistribution is used where calcareous materials
occur on only part of a site. Excess alkaline material is redistributed to the portions of the site
lacking alkaline materials.
Benefits
Blending of calcareous material in the spoil has the advantage of being accomplished during
the regular course of mining.
Dark and deep (i.e., submergence below the water table) has the benefit of limiting oxygen
available for pyrite oxidation.
Alkaline redistribution results in calcareous rocks being distributed to parts of the mine
where they did not occur naturally, thus providing the benefits inherent in calcareous rocks.
High and dry, if material is capped and placed above the water table, should reduce the
transport of pyrite-weathering products.
Limitations
Blending is only effective if the calcareous material is can be adequately mixed in the spoil.
Geochemical Controls
2-121
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Ill IIIII III 111 111 111 I III 111 Illllll II 111 II 111
III 111 I 111 II Illllll I III
III Illllll I Illllll 111 I 111
Coal Remining BMP Guidance Manual
lii ni i i i i I i i nil ii n ill 11 in i MI in in i i n i i i in
Sites that can satisfy the requirements for "dark and deep" do not always exist in the
Appalachians due to thin saturated zones and fluctuating water tables.
illil W '">' ,!!T IE," ISPI'i,!!',"! "II'1 111.'I Jl, ' II. li
and dry technology has been inadequately studied and some of the studies are
w .t; p f ' > wsiin ;ikji; w ...... i -. i* v$ > " \ซ/i :,:;; if 'i,:; : I
l' 'IP
iii'i::1,,11 ISHNilr1 -, ft!
Rlending is the most common handling method, but is not strictly "special handling" because it
ill ji iiiii,; .I,)* a?!1 11!1 :; sijiiiiiiii1'" .jiiiiii, i!"1:,: ..... vs.:1"!1'1 ซ ''iyv ii!';KJi ' l!* ; '.:' <: ....... iiini1; i f.r! !.'< ซ.: 'ซ ..... >. I" iHii ..... 't*1! 'in ..... ii< litiini!1!!1!,, :t ซ itf ii.w" ..... ii>( ' i'UKv: '"'i > ..... it = 'livuwvi
gllllllllllllllllll..^!!!!',; !!l|!i ill ....... II ....... llllliillilLLl.!"1 IHllllllllllilllll1 ii ii'lilllliillll, i i ..... "', ill .Mill ..liiill'ii. ..... I1"1 IIP 'ilhli ,' i 'ii i' :: ..... ...... ,' ilill ....... illt'T'i Ul P'T |i ".lll'inill|i|"ii I ..... lil ....... ''!!, hlllli 'II il/ipilllllii Ji'lllli1,1,,, i'i ' ' ..ill 'ililllllll'll'l.'llllll1,:!11 ""Mi'1 ..... lib ...... IlilP'1 Ili'll l.niilll i,! ....... P ,i PIP1 ', " i.'i'Vlill1! ' i|li ...... ,' ..... 'IlLrli irl ,1, : ....... I'l.'lp, .....
ap,oeง no| require additional selective handling of materials and is accomplished as part of routine
l !^t ..... l"lfli ...... ffj.^feirw;'. ..... ' ...... l.'"ซ ..... EgKt;
. The many sites in the Appalachians that have compliant post-mining water quality
..... iiiiiit! ..... IK sฅ> ih ,:?!> IB,I' IK :.. f]i, ...... i,, iksiR: M, \& : t 's " - : ..lii-iirita'1!!^^^^^^^^^^^^^^^^^ ,s:; ,* rjiiiuw^i'i. "iwf, ..... WZ-L ' it si; ii m tm>i;
its ....... success., ,,The key is to have sufficient calcareous ..... strata present. The success of
i. iiiii:
this method is probably reflected hi the fact that mines that had regrading and revegetation as
gt^eir^onlyJBMPs (Section 6.0, Table 6.3g) had acidity improve in 50 percent of discharges , with
, ซ$}ฃ other 50 percent remaining unchanged. As discussed in Section 6, remining operations in the
; Site Study (Appendix B) that implemented these
. ;, i ', .....
, ; i ;a ' i ir S
, . a/i'i1 i ' ti'
ft hi :; ii;5ii-
,
p^ contained better overburden qualrty than many of the sites employing- multiple BMPs.
I ! i' !!.' ' ......... ::i:';. ...... im*tl ! i ........... ! ?':' ..... ii!l::i:; : ' it1!;1:' C ..... , !!" .i1 '< ' . , ^ : "f": : ..... ! 'I ' ..... 3ซ " i ' >i .:?;;' W.* mW" if i ........ 'If ปC! 'MV< i M ; '; ....... t ;* Iii;. iiiii ..... ii''
' ' '
Hi ......... i i ,! ...... i,: 'i ..... I'v'
'I'lilllil" i1";*' ill'l'l; !
Ii: "II I
'ilifllS1;1,-!11!!
The effectiveness of high and dry placement is not as clear. Studies that have been performed
are few and some are inconclusive. High and dry is the most commonly used special handling
.^method hi Pennsylvania, and it can be assumed that most of the sites listing special handling as a
'" ' i I
illiiilinif HI P
hi the Pennsylvania Remming Site Study were using this method. Data from this study
i'
were used to predict the effectiveness of special handling for improving water quality during
remining operations. Section 6.0, Table 6.3a shows special handling can be predicted to result in
slightly lower water quality improvement in regards to acidity loading than can be predicted if no
BMPs are implemented. Section 6.0, Table 6.3 g provides some different insight into the
I
effectiveness of special handling. Special handling in conjunction with the minimal BMPs of
jepading and revegetation, resulted hi the same effectiveness rating as did the combination of
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regfaduig and revegetation alone. As other BMPs were added (regrading, revegetation, special
2-122
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Coal Remining BMP Guidance Manual
handling, plus other BMPs), efficiency generally declined, with less discharges showing
improvement in acidity load. This is probably due to the presence of greater amounts of acid-
producing overburden and/or lesser amounts of calcareous overburden, with the additional BMPs
added to offset the effects of the poorer overburden.
When deep mines are daylighted, there is often acidic material that requires special handling.
This acidic material is typically unrecoverable coal and roof-rock. Section 6.0, Table 6.3m
compares the implementation of daylighting alone to seven other BMP combinations. Four of
these seven BMP combinations involve special handling. Three of the four resulted in a higher
percentage of discharge water quality improvement than daylighting alone. Two of these three
successful BMP combinations included the addition of alkaline materials. The fourth BMP
group included a combination of five BMPs that routinely produced the poorest results. It is
suspected that this is because additional BMPs were implemented in an attempt to counter poor
quality overburden.
The dark and deep method of special handling has been shown to be a good means of AMD
prevention. Its usefulness in the Appalachians, however, is often limited because of a thin
saturated zone and a fluctuating water table that allows the acidic material to be exposed part of
the year. The effectiveness of dark and deep cannot be evaluated using the Pennsylvania data
because it is used so seldom.
Alkaline redistribution has had a high degree of success. Evaluation of the Pennsylvania data
(Section 6.0 and Appendix B) suggests that alkaline redistribution has been a very successful
special handling practice. Section 6.0, Table 6.3a shows that the predicted odds for improvement
of acidity load when alkaline redistribution is used is eight times greater than when no BMPs are
implemented. The only other BMP that gave a greater odds of improving discharges was mining
of alkaline strata (nearly 19 times greater than when no BMPs are implemented).
Special handling by itself may reduce acid production, but it can not produce alkalinity in the
absence of calcareous materials. Special handling in conjunction with alkaline addition or other
Geochemical Controls
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oฃl B^MWIMS BMP Guidance Manual
rie^M of incorporating alkaline strata can result in better water quality than using special
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Special handling is often used in conjunction with other BMPs such as management of
ground water and alkaline addition.
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Subrm|rgence (dark and deep) is seldom used in much of the Appalachians because the
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"saturated thickness of the water table is generally thin and the water table can undergo large
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* Special handling in the absence of alkaline materials cannot produce alkaline drainage.
Special handling often involves both acid and alkaline materials and may also include clay
materials for capping and lining pods of acidic materials.
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f Special handling is most effective in conjunction with other BMPs such as alkaline addition
i surface- and ground-water management techniques.
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The volume of the material to be special handled should generally be less than 20 percent of
the mine backfill volume because of the need to keep acidic materials away from the surface,
Water table, highwalls, etc.
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,. i , Ggocfyemical Controls
-------
Coal Remining BMP Guidance Manual
Special handling is not necessary on all mine sites.
Identification and segregation of acid material is extremely difficult if multiple zones exist in
the stratigraphic section, unless these zones are persistent laterally and vertically, of uniform
thickness, and distinctive in appearance.
Special handling requires that the proper earth-moving equipment be used at the mine site.
Monitoring during and after mining is necessary to evaluate special handling techniques.
Geochemical Controls
2-125
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2-126
Geochemical Controls
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Coal Remining BMP Guidance Manual
2.5 Bactericides
Introduction
Bacteria can play an important role in pyrite oxidation. They can cause pyrite to oxidize at a
much faster rate at low oxygen levels than would occur in the absence of bacteria under the same
conditions. Bactericides attempt to block the catalytic effects of certain bacteria on the pyrite
oxidation process.
Theory
Pyrite-oxidizing bacteria, in particular Thiobacillus ferrooxidans, are responsible for the
increased oxidation of pyrite over what would occur abiotically (Figure 2.5a), especially at low
oxygen concentrations. Although numerous bactericides have been tested against pyrite-
oxidizing bacteria, the bactericides of choice for mine sites have been anionic surfactants. These
bactericides occur in household cleansers and soap products. At near-neutral pH these
surfactants generally are considered to be poor bactericides, but they are markedly more
inhibitory at low pH (Kleinmann, 1998). T. ferrooxidans has a near-neutral pH internally, but it
can exist in low pH conditions (in fact, the conditions that it creates by oxidizing pyrite) because
of a coating that protects the cell from the externally low pH environment. Anionic surfactants
dissolve the protective coating, thus subjecting the bacteria cell to low pH conditions, conditions
under which it can not survive unprotected.
Geochemical Controls
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Coal Remininz BMP Guidance Manual
figure 2.5a: Rates of Pyrite Oxidation with and without Iron-oxidizing Bacteria (In small
columns maintained at different oxygen partial pressures) (Hammack and
Watzlaf, 1990).
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isiThe amount of oxygen present within the gore gas of mine sgpil or coali reftise is an_ imrjortant
Ifactpr when considering the use of bactericides. Figure 2.5a shows pyrite oxidation rates under
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:s are about equal. Below oxygen levels of 14 percent, pyrite oxidation rates are considerably
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slower when bacteria are absent. In the presence of bacteria, pyrite oxidation can be significant
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;Ky^^^xy^en g'^jjgl^jf^gons'as low'as one" percent" "Thus bactericides 'are" most' advantageous
'l^ljere^oxyg^n concentrations"are low! '" '' '""L ""
Bactericides have a limited period of effectiveness, and typically are only effective for up to four
months. This limitation can be compensated for by repeated application or by application of
: time-release pellets.
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Coal Remining BMP Guidance Manual
Cations such as calcium and magnesium can cause water "hardness" which can reduce the
effectiveness of surfactants in much the same way that hardness reduces the effectiveness of
soap. Calcite and dolomite, which contain calcium and magnesium, are common minerals in coal
overburden. Kleinmann (1999) felt that this surfactant inhibition would be greatest with highly-
soluble neutralizers such as quick lime (CaO) and hydrated lime (CaOH2). Something to keep in
mind is that bactericides in-and-of-themselves do not produce alkalinity, and compounds that
produce alkalinity frequently contain calcium and magnesium which may inhibit the
effectiveness of bactericides. That is, the minerals that result in acid neutralization can retard the
effectiveness of bactericides.
Site Assessment
The initial site assessment for bactericides is similar to that for other geochemical BMPs. First,
the acidity- and alkalinity-generating potential of the site should be determined by evaluating
overburden and water-quality data. If the site has little or no potential to produce acidity,
bactericides are not necessary. Kleinmann (1998) points out that application rates of anionic
surfactants are site-specific, and heavily dependent on the adsorptive capacity of the material
being treated. He suggests that pilot-scale field tests in plastic 55-gallon drums'be used to
determine the adsorptive properties of the surfactant. He cautions that small test piles may not
accurately simulate larger sites because of higher oxygen concentrations in the small piles
(Kleinmann, 1998). Determination of the amount of adsorption is important to assure that there
will be adequate bactericide available to combat the bacteria on the surfaces where it is needed.
It is important to estimate the oxygen concentration in the mine spoil or coal refuse. For
bactericides to be effective the oxygen concentration should be relatively low (<10 percent).
Most experiments with bactericides have been done on compacted coal refuse. This material,
because it is compacted (and often contains a high percentage of fine materials) can have low
concentrations of oxygen. The use of bactericides at surface coal mines is potentially less
effective because of likely higher concentrations of oxygen. If oxygen levels are high (>10
Geochemical Controls
2-129
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iii'iE' """ii '-;
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i ll'pfeffcenQ there may be very little benefit from bactericides because abiotic pyrite oxidation is
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icigat to create significant amounts of acid.
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1 '"Spoil pore gas oxygen concentrations can be related to the type of rock that was mined, or
disposed of (in the case of coal refuse). Some examples of oxygen levels in pore gas, which can
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serve as guidelines, are given below in the literature review/case study section.
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Site evaluation should[include assessment of:
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JB: "til,;: \w.LOfsum! ;ซ 'aii i f- v, M.S ^i* iwi s .^jiiwni'Ji'i/ti K, r' M1. ^ r. f'Sii .:!f;:!i ;u ป< DW utซ' '..* ? w n. i^:.
B!* .^.iLntneA^rproducing potential of the site
lii'i, 1,'i"' :,i!''il'ii,ii'':'' 'iiliK * , 111,1, ซ , '!, ,,ซ! ,,1,,'H" I/ r I. ,, !,:, ' 'i : ", , > II',,, ;
....... I *.ซ , ,!l" ......... ,! iiliiBi ' W.Wilii ..... I
s s "it t u ' :' ; ail:;
iliK nv ii'l
I!!:!!1 lซtHlli,,' ..... ':
the adsorptive capacity of the overburden
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:;:'."!i 'I'lBBIII. 1! i ""
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f prediction of the percent oxygen in spoil or coal refuse pore gas
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he fpllpwuig guidelines are recommended for application of bactericides:
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should be targeted to treat unweathered acid-forming material, such as coal
'
i(if-i::s-:i!ai( ..... i ..... ii!'iปi!j:it':!^L:*ii^,r. ..... aiW.H ...... ^.^i^'ifrf^ ........ "nปflia'$i.^.i!iw: > ..... 3::'r^
refuse, that can be quickly buried.
! !;: " ..... f W:* ''MM ..... ..... ;! if! IL liiii; ...... SIR. ..... i"1 s' i'M . ..... i ......... ' ; a:! ...... . t ..... i ;t; ...... w ,nfc i* iy;i ms ..... !,;; m: . \ ^ ...... 'ii ..... * * f
IIP f|S:!III ";':il'I' '* \'' ;,;; ';" 'J. j jhgy should be applied ^at a rate' higher than the rate they ^are adsorbed by the rock.
should not be applied to soils if the intention is to treat spoil, because soils will
idsojb me surfactant leaving little to act on the underlying spoil.
They are probably only effective where oxygen content is low (< 10 percent), thus an
m'i^im '" *,' : ii r li ' ...... ii S38 oxygen should be made.
[I ilii'ii I ปfT ............. *' O" ',ri ...... ; ' IIHi'F ill ...... liiWffrjW^.'! iiilillli.::,1' ii" f l^mtilSaftWi, I ...... ilf I!1: ' '!li:ii! il WWi'l'MIt-V .'it'!" '' !'.
i ..... I ...... "1 "111 .:J&S '"5 ..... 1, II fi'iSV" ...... fs:f; *ฃv'i> i," ..ซi -"ii ..... '1 ..... ratiliiii',
iSSl'Bi |;;, 111 I'111 *i* ^";:""hงurfactant.solulMns can be applied to acid-producing materials prior to their disposal.
W'Fil|iii;Sl||"!'; ili:' |!'':;l| ,,-i^^^^ "'- il m miim>
ijljl i^)'.:*!'; ' v;" ilp'!: I; jSllPtime release pellets can be mixed with the spoiled material. Both methods may be
mifsii,!|4j 'i- i' HI.wi'liii1 |,l^jij'M' i|' i|ii"'1!!:'::,'if*'|ฃ',:i;i!,:''i,;!!,r-;wt|:|W;^,V:iฅ... i-,ป IWii'If ^Mi..^! ill 1!!^^"'. Ii1;;!- , i/:5 ,:i!:,;"isy 1!;;,;,if,'ซ
Jli^jiii':^',^ ;p;:" jj]||ti:^',^jij^^^^ fel^Rlr^6,',ฎ:^0^6.?16: jf H?^ ^"^ฐ!u,^ฐ^ '^2> ^.^^l^^y ne,e^tฐ1
lซ l' r' i ^ ^ ^
p CarTO content may also be important. Kleinmann (personal communication, June 28,
ill! i' if f, .' 'iiiii! 'M^M '^I^W's J!,ii,;li is!! i, ^m !"'i'; iซ 16, w .1 M - ii m*ป ป;!m m&i & M \iw. u :^m^ >;.;;:? && a
ii'ii'! .*.wi.i'-ii ii,'i
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ii'iii'^il
that high calcium water can inhibit the effectiveness of some anionic
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;";";; '*! "^ ;'';''|ii|Surfactants.i|iMore soluble neuiralizers such as hydrated lime and quick limes are most
":',!,!'! 'iiii". 'i iii; i,:,,: ii!,: .'
i,; "!', i'lii'il"'!1 i''ViW'ii;:,!' 'i ''ill! i I!" Ii" i , 'I"":: ''Si,':,: l-l f "U!1,: M' i, i,":'!!"1! i, '.iiiiJii ,,,if i
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Coal Remining BMP Guidance Manual
problematic. Essentially calcium can cause hard water and inhibit the effectiveness of the
surfactant.
2.5.2 Verification of Success or Failure
As with all BMPs, bactericide application should be implemented as described in the plans.
Means of documentation include:
Engineer's certification and increased inspection frequency to verify that the bactericide
was implemented as planned
Photographs of the bactericide application
Locations of bactericide applications being accurately recorded through surveying or
global positioning systems
Verification of the amount of bactericide used by submittal of receipts.
Laboratory analyses of the acid-forming materials to assure proper placement of
bactericides
Water-quality monitoring for flow and concentration of mine drainage parameters and
bactericide.
Monitoring of water quality and flow, as well as accurate documentation of implemented plan,
will allow for future improvements in design and determination of the efficiency of bactericides.
2.5.3 Literature Review/Case Studies
There are a variety of substances that can inhibit pyrite-oxidizing bacteria, but Kleinmann (1998)
states that only anionic surfactants proved to be cost effective. Kleinmann tested, in the
laboratory, the relative effectiveness of three anionic surfactants in preventing acid formation.
He found sodium lauryl sulfate (SLS) to be the most effective (Figure 2.5.3a). Higher
concentrations of the other surfactants were required to get the same effect.
Geochemical Controls
2-131
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Coal R&mining BMP Guidance Manual
^Figure 2.5.3a:
Effect of Anionic Detergents on Acid Production from Pyritic Coal.
(SLS = sodium lauryl sulfate, ABS = alkyl benzene sulfonate, AOS ="
alpha olefin sulfonate) (from Kleinmann, 1998).
'11,11,; ; i nilii a!!!!;;:,
SLS
ABS (Witco)
ABS (Pilot]
AOS
1O 15 2Q 25 3O 35 4O 45
Anionic detergent (mg/l)
5O
As mentioned earlier, an important consideration as to the effectiveness ofbactejicid.es is pore
gas concentration of oxygen. Oxygen concentrations in pore gas have been measured for refuse
i
: material ,Md,forsurface mines, Gup and Crayotta (1996) reported oxygen concentrations with
in:
l!!!Wi!ป 1IM^ , ,:
"PI* L:iiii!iiiii, up!' lii! i IF " ' ..;,
I "s
depth for two surface mines in Pennsylvania (Figure 2.5.3b). Mine 1 contained predominantly
lhale/siltstone overburden and Mine 4 contained predominantly sandstone overburden. Mine 1
shows significant decreases in oxygen with depth, with concentrations as low as 2 to 4 percent at
ง1, meters.'"'By contrast, oxygen was never below 18 percent at Mine 4, even at depths of 17
li:J";-',il:!"!'' lift 'mw%' ". ' >[ 9'i'i f isi;rail w* ; m: :'!:' i ซ i vr;;' * -,ii im i,;ซ.,.rat...'.;ป?ป ^i ^ - ' ซ.ป u-si r
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Qeochemical Controls
\
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Coal Remining BMP Guidance Manual
meters. This is probably due to the blocky nature of the sandstone which allows more
atmospheric exchange than the smaller-sized rubble resulting from shale/siltstone.
Figure 2.5.3b:
Measured Profiles of Oxygen in Unsaturated Spoil (after Guo and
Cravotta, 1996) (At Mine 1 gas transport is by diffusion and at Mine 4
it is by convection. Mine 1 has shale/siltstone overburden and Mine 4
has sandstone overburden.)
MINE 1: Borehole N-2
0
-2
-4
-6
fc
g-10
-12
"02 46 8 10 12 14 16182022
OXYGEN CONCENTRATION (vol%)
+
EXPLANATION
MINE 4
@ Borehole T-1
O Borehole T-2
O Borehole T-3
MINE1
A Borehole N-2
-f-Borehole M-2
X Borehole S-2
X A +
O
"02 46 8 10 12 14 16 18 20 22
OXYGEN CONCENTRATION (vol%)
Erickson and Campion (1982) report on oxygen concentrations with depth in coal refuse for sites
in Pennsylvania and Ohio. The results of their measurements are shown in Figure 2.5.3c. All
gas probes were installed at less than one meter deep. Three of the four plots show similar
declines in oxygen concentration with depth (PA Fine, OH 3 and OH 4). The "PA Course"
refuse had substantially higher oxygen concentrations at a depth of 36 cm than did the other
refuse. The courser nature of the refuse apparently allowed for greater exchange with the
atmosphere.
Geochemical Controls
2-133
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'gal Remining BMP Guidance Manual
i, inn i hi!. , ." ,1'i'lli
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i
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!' ฃ;i; "
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o
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Q
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PA Course
-OH 3
OH 4
100
0
T1 I]IIII I III I III I I I I
10 15 20 25
Percent Oxygen
The course refuse had less than 1 percent oxygen at less than 1 meter, whereas oxygen
concentrations in surface mines had 12 percent and greater at one meter depth. At 7 meters, the
surface mines had at least 4 percent oxygen, even where the overburden was shale (a rock that
breaks into small sizes). There are a couple of explanations for these results. First, coal refuse is
2-134
i Ggochemical Controls,
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Coal Reminins BMP Guidance Manual
generally composed of highly pyritic material that will consume and deplete oxygen near the
surface. Surface mine spoil, by comparison, is lower in sulfur and oxygen consumption is not as
great. Second, coal refuse is typically finer-grained and more compacted than mine spoil. This
permits less oxygen exchange between the pore gas and the atmosphere,
Case Study 1 (Preston Co., WV) (Kleinmann and Erickson, 1983)
This site was an 8-acre active coal refuse disposal area. Because the area lacked background
water quality data, a pond was constructed to collect runoff for monitoring purposes. Adsorption
tests indicated that an application rate of one 55-gallon drum of 30 percent SLS would be needed
per acre. The bactericide was diluted with water by a factor of 50:1. A larger dilution factor
would have been preferred, but good-quality water was limited.
Water quality improved dramatically within a month of the SLS application. Acidity, sulfate and
iron were reduced by 95 percent and remained low for approximately four months following
application (Figure 2.5.3d). A complicating factor with this study was that coal refuse not treated
with bactericide was added during the study period. It is thus impossible to separate out whether
the increases in acidity starting at 120 days was due to this untreated refuse or diminishing effects
of SLS.
Geochemical Controls
2-135
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1 IIIIIIIIPIIFI111' "1 Id,""!"1
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viiEi ..... iiiiiiPiiiiJfsiiiiii:::!.! .lin!!!1!:;;11;1,,!!! inn I
Figure 2.5.3d:
Effect of Sodium Lauryl Sulfate on Runoff Water Quality at an 8-acre
i' it. Nil I I I II Fi i I j ii'! , 1 ' '' ' i' I: ' !' i: i '' ! . " i.f 1 , , !. ill
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Acidity
-ASulfate
-o Iron
20 40 60 gj. IQO i 20 140,
TIME AFTER TREATMENT, days
160 180
Effluent concentrations of surfactant remained extremely low (consistently less than 0. 1 mg/L)
iimini; , ii.'iiin i, !'i,ซ'! 'I.!, iiiiiis1! ' ti.iiJM1: IIIIHIIIIIH mi::1 : ' ....... .iMiii.ii'iiiinll1 JLP iiiiiiiiinmli ..... '. iiiiiiiiliiil ' i i-'i-llr ....... u'v " ,~ 'miiiliii .1' i:l TU < - Jii; "iiiriiyn1; , ii,,1;!1 :; iii.'ii'',:; rii.iiiyi;..1'':. ..... "!,; " nijii,,,^ ............... > ......................................... / ........................... < ........ O /
'^"';i*|; ' ..... *5s?yiromghout application with none being detected in the receiving stream.
' ' ' ' "
l! SSr ::"' ' illiO :, '!' ..... W ; . V ' :,': ..... V ', : Sf, ?' ' :. I . ' I ' !' - ..... ...... - ' i; JS1'!:1:" m :ffi'^ 'it I "" I . , "-' , ' i! ;,/:: W 31 ,i 5B * " . , !: "5 ' i. '.'\ , i" 'I:* Kit ' ...... Ill1 ''III' ". I
, Eliili!" J ........ : '' ;,; I ...... H! 81 ..... ' 'Illli :ซ ::!lilli; i , . If ..... IIS ' .'-II, 'ift ,;. , "!' ..... Hi ......... - . i ".f; . f !' .? Jf i '1 ; ' ' ; I ' !:! 9 - i: ...... i'3" .'Silliil **ซ 1 1 ' ; ':
, .
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:::: ;;;:;:::;; ...... '-Case Study 2 Ohio (Keinmann, 1998)
This site provides a long-term evaluation of bactericide application to a refuse pile. The initial
2BfllSlงi JS Jlง4tethe Ohio Department of Environmental Resources. A 2.5
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2-136
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Geochemical Controls
ii ii11
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Coal Remining BMP Guidance Manual
acre area was treated with SLS and an adjacent 2.2 acre area served as an untreated control. SLS
was applied in solution at a rate of 200 Ibs/acre and as pellets composed of a rubber matrix at a
rate of 500 Ibs/acre (containing 16 to 28 percent SLS). Both areas were covered with 6 to 8
inches of topsoil which was fertilized, limed, seeded and mulched.
Five years after reclamation, biomass production on the treated area was 9 times greater than the
untreated area. Acidity in the vadose zone in the treated area was 80 percent lower than in the
untreated area. After 10 years, 35 to 40 percent of the control area was barren and eroding,
whereas the treated area showed no significant erosion and the vegetative cover was dense.
Case Study 3 West Virginia (Skousen and others, 1997)
A 35-acre coal refuse pile was first regraded. Controlled release surfactant pellets were applied
to the surface, which was then topsoiled, limed and revegetated. The treated area had a pH of 6.2
compared with a pH of 2.9 in a 1.2-acre untreated control area. Acidity was as low as 1 mg/L
compared to 1680 mg/L, and reductions in iron and manganese were equally significant.
Case Study 4 Ohio (Skousen and others, 1997)
Bactericides were applied to an abandoned surface mine that was poorly vegetated. The
application was in the form of slow-release pellets that were spread by a hydroseeder. The
overburden was predominantly sandstone with abundant pyrite. Seeps with acidity of 1000 to
3000 mg/L have remained acidic, showing little sign of improvement.
Case Study 5 Appendix A, EPA Coal Remining Database (PA (10)), Somerset Co., PA
Details on the specifics of this site are presented under Section 1.1 Case Study 3 in regards to
Control of Infiltrating Surface Water. Multiple BMPs were implemented at this site including
surface regrading, scarification of calcareous pavement (seat rock), alkaline addition, hydrologic
Geochemical Controls
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Coal Remining BMP Guidance Manual
.;-;,-; ;; ; ; ; .; ,u controls, and bactericides.,:The bactericides; were applied in the form of time release pellets on
iiiiliiiiiliililiii:ilIvi'l Iiiซ, iiillllliiiiI11 'I:,/ liillii I l,iii''iiiiii& ill.' l1 IIIL I1. ,i,," .'' iiiiiiijiliiili
i"-'; ' ":: ';:;:: the,spoil surface prior to spreading of topsoil.
lilt illDliU IN-l'lr ,, '"ll I 'HIEIfl < i< 'ill. ,"|:"t" il!!ii>i:,iil ; i,l|i|llll!ป .illlllillll, I"' IBr'l I! ซ::' 11 illi, ' r '111! ill ji ', , '*' ' ! 'lll'll ill: !!:, I < ',':. ,4 1- 1 :" ซ'.., :'JJi I." I- V iWtlJ'W ..' I ," l''l'll|l|l> .1 ,ft' illllll"!'!"! HIE1 IIITliI] illv'Mlli |
liii'i iisi'tii: i,;.'' iiTi f',s:'i'" vm-'timr""IBII ' siyi:, > ::u t vM.11.;' i; ? i *,\'" '/ ii f-1 i;*! i *w< s " i 'i M :; v1' ui i;1;v :f\ftf W;,:i'Sii* MM ',;. :t'. fK:,; 's ...'h::n':*t isiPiii.', is
M,S^ps have had increases in acid and sulfate post-mining loads compared to baseline
'M a, iiiiiiiiiiiiii'tlll'liiilllliiilllli1 ป'i 'iiiiE1'
.........
loads! ......... The other two seeps show no significant statistical difference in load. In all cases the
l i ilirili'Mi f >,i,i! {"iii'Iiilii'iiliii'i1' nillllllil ..... ',! (SI illllllilllllllliir11! Llil'iilF B'!1"'1!!!1!/!! IPI' ,! ll'.'Viri .......................... ..... ?"; ........... , ..................... ............... [[[ [[[
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or acidity havejncreased.
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A blend of polymers and a bacteria inhibiting agent were formulated to retard acid soil formation.
muni/ i11 in,inii<
-ir^
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!:llill!!iliillll>>;i!PB:i\h;illl>lll!t!il1W ' :ฃ! "1 IIIIRII !' 'lllli'lh "'n|!' 'rM'likv:/ liiiililllilllH^^^^^ nillBliiL "'in'ikl'.ii ...... II Kin:.1!1 Hi 'UK ....... :. ..... I'fltlill," Vt A ....... , ................ ^ [[[ i [[[ .......................... I ....................... ........................................ n
. vfiiiliiliii,,, 'I, lillLif Jir;;:! ' ..... I'liiirriiigilil
^ 'Tiinillii" LJllIU'1!!:;!: ..... iii' ill ,ป '!':: :^WK llJillni !!"
'.!!^':;:!.!!!''';]!,:!! '<;i, iiii- ' ' :Q 'p1 ...... !i ..... IMI:1!1,!
..... UiiiiJkH^ ..... JIlllliibDiiil'llli .'"ill"^' ^liiIiLlilllillA!'' ซ1K :l': j ..... I
i|!n^ ;i^'^i^^e..i^9.9{,iil^ addj|^QQitQ^bacterjici4^Iiis.e, the topsoil was limed, seeded, fertilized and hay
I' I ii'linillllllilil Jiliiiu ': i 'If Jiiil1'' JIIK^^^^ IL1;!'! Jlll'in1'' ll|lซiil!IIM^^^^^^
mulched. Erosion control blankets were applied to reduce erosion and to protect the seed. Tree
,;,";, ;;;;, ; i;'i,I!"" ,i,I"Z"", ","',""',', !" l ""I,"" I" ,~,1,~ i,
Illllll | i in i mi n n n i in i n n i in 111 iii f ''ii'ini'i liiiii, ill1:1'" iiiiiinihiiiii'1.: .'.' .'ui'iiii 'nil 'MI " i'" HE 'f' "iiii.' i1 ii! i i iini'i i' i, "Hi"!'. iitt, 11 : j' s'' i ;.i; in 'iiiiiii J iiiiijiniiiiH^ ';/ iiiil1 > ./ill' KIII' WIN ' :i 111'.:" I'm iw iiun
seedlings were planted on slope areas. Vegetation remains successful after more than a decade.
!f!!*jiWf]ง O'rH;, ;'i (r'lll
^^ , ;,,,;;; ;,, ,.^. ^^g^'JQljg^^jlQjj'
!'ป*; ;|;";,::!i-;:i;;;';|!:!]|:iif^^^
IK 1
,!',,liii!'!' ii"',, !iป '.i/nlPlvti 1 ..... iil
ll11 i 4< /.s'liSii,,; ' in1"!1! ,Pi
> ,|i :i "', "i; .."Wlk.!1!1 iu > . l1 ' : ..... II! Ri 'IL lini
...... i! ...... ! ..... li'Ll lil
M;. '* ,, ..... ' i !Jiii "PW liilllllll, i ' IIBUill!1/.1"'1!
$$ง& Ste$fiง.งVSฃest ^at bactericides have been successfully used on
''" ' " ''' ..... ''" ''''''" "''' ........................................... ........ ..... ,. .......... .............. L ..........
^iSJ^Iji , , .
piirpo'ses (Case Studies"":!1 and 6)!'1 ...... Case' Studies '4 "and 5 concern'';^]^^^^^ฉ^'''ฉ f''
i;i!'' 'is^^^^^ i;i!i![ ...... ซi! ...... |
I bactericides at remining sites, and in both cases the water quality was not improved. This lack of
"
I improvement at remining sites containing abandoned surface mines may be due to the high
1 ""! f! !:! ' '" '"'""' ' ''"'" 1|! ' jj^^
"ions present in spoil pore gas, the large volume of material that needs to be
and adsprption of much of the bactericide on non-acidic rock. An additional
, _ ,
with surface mines is that calcareous strata or alkaline amendments may cause
water hardness that can decrease the effectiveness of bactericides.
^^iactencid^.ai^r^,gulated under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).
IIIK !|f : "'i . IIIIP iii' I'lHR. waime liiiiH^^^^^^^^ ii'ป / '..ini.; !!
Only bactericides registered under FIFRA can be legally used.
BlJKu I Jlllf P
...iliiiEi i:, ,,irinii!!' jffTiffiiiiiii;,' niiiiiiJIBUi' iViiiniiiiui ir,!
mSjji' jyill* h, "I'JIiJ'jjJ!:!;1"'1 ;J!!*j ,! .' iiiiijSS-! j 3 8
I " I'":4 ilR''. >!m$'' if
'' " ""
Geochemical Controls
'.i'Ll iT1!,",::,* ',"T1| .si | ilMln,,:1
iii I'liv'1!'1" '{' ,1,1'Fi::> *' ;|i H1"'''' i\': jj) i,"'; i "fi'i If I'1'1!:l|''1'1!"'', ''!|iiiii iii''"i'' "i''!''!^!!'''11
u, ,
:: 'i :
-------
Coal Remining BMP Guidance Manual
Benefits
Can inhibit pyrite oxidation in low oxygen environments
Can assist in revegetation efforts by acting as a wetting agent.
Limitations
Limited to low oxygen environments, such as coal refuse disposal
The bactericide will be adsorbed onto rock and soil, thus an excess should be applied
Bactericides have a limited period of effectiveness and should continually be replenished
Works best on fresh materials
Limited by the presence of certain cations (Ca, Mg)
Efficiency
Not enough data regarding the application of bactericide is available for statistical analysis.
However, review of the case studies cited above allows for some tentative efficiency statements
to be made:
Bactericides appear to have successfully reduced acidity at active refuse piles where it
can be applied directly to fresh refuse.
Very few studies exist for surface coal mines. The two case studies cited above were not
successful. This may be due to oxygen availability in surface mine spoil. Another
complicating factor is "hard water," due to the high concentration of calcium and
magnesium. Much of the bactericide may be adsorbed on non-acid-producing rocks, thus
diminishing its availability for acid-producing rocks
Can be effective for enhancement of revegetation efforts by acting as a wetting agent
Geochemical Controls
2-139
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Coal Remining BMP Guidance Manual
2.5.5 Summary
As a remining BMP, the evidence to date does not support the use of bactericides for prevention
of acid water on surface coal mines. It appears, however, that bactericides have assisted in
I I IIIII I! Ill II11II I I 11 III I I I III II I III III I 1111III I I II I III I I I 'i', ' Jni. if ' ,,'iii ,||i| ''II1',;, i iil'iffii'i!'"', !'lilliifv,' !ซ: MM lillllll.!:!,' '', iii!''1 <'' ;,ป ฃ ' I'll,! jl. ill.1 lii:',||lil"iWI fJiliiifti!1; fiiiiiiilPI < I1' :,' ' ' ill |
enhancement of revegetation efforts and bactericides have successfully reduced acid production
from active coal refuse piles.
.J,
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j^..^"^^": ,;';ซ'!ฃ!$ ^,S2E22UI2iiPn Surface Mining, Hydrology, Sedimentology and Reclamation, Univ. of KY,
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^ Ifl I"1"!!,'!!'!!,' TIIL1
III' t11! illl ui1'-! liiniiiiii'i" i J '
2-146
Geochemical Controls
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111 111
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Coal Reminins BMP Guidance Manual
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Rose, A.W., L.B. Phelps, R.R. Parizek, and D.R. Evans, 1995. Effectiveness of lime kiln flue
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Rose, A. A., Williams, E.G. and Parizek, R. B., 1983. Predicting potential for acid drainage from
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2-147
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, Lg personal communication with Keith Brady, 1998. Details available from the U.S.
,^,
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: Kii1'! n.-.u1,1 ''-iijrn^ 'iiiiiiii:1 '"iiiii*1'1'!''.!: "iiiiTi'i*ir'^iV'+'iia'S.!'" i,n ii N< ,1 JIL'iiiiji/1 " "jniiii11i, ': i/i< ^i,,liiiiFni'. ifffli rw jiiiihiJiiTi, iriiiiii'iiFiii;,, "":;iiiiJL'ifflfk11 ip'iii'iii'ii.Hiri/.iriifeii111" jiniijii'^iiiiriii11,.11,;!, ""'"inn .jinii! iiiiiHt'iiii1,!
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v' - 11|ii|i|*!ffgg| acid"nSe'Sralinag'el!.l'1'^S. Bureau "of Mines Special'PuWicatibn'SP 063-94")"??".' 375-38'l". ""
i Skousen, J. and G. Larew, 1995. Alkalines overburden addition to acid-producing materials to
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'"' ' ~ '"
Skousen, J.G. and G. Larew, 1994. Alkaline overburden addition to acid producing materials to
, [grevent acid mine drainage. In: Proceedings International Land ^Reclamation ^and Min
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^^^^^^^^^
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ii'i'lll'l jjjjjiUv IIIIIIIIII HI 111 IIIIIIIIII i iiiiiiii III II I 111 I III niillii I 111 III l lllllllll n ill lillllll ill l l ill llllllll ill ill n
Slpples containing siderite. Journal of Environmental Quality, Vol. 26, no. 3, 1997, pp. 673-
$1.
Skousen, J., A. Rose, G. Geidel, J. Foreman, R. Evans, W. Hellier, and members of the
Avoidance and Remediation Working Group of ADTI, 1997. Handbook of Technologies for
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(ADITQ, Published by The National Mine Land Reclamation Center, West Virginia Univ., 1 1 1 p.
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Coal Reminins BMP Guidance Manual
Sobek, A. A., Schuller, W. A., Freeman, J. R. and Smith, R. M., 1978. Field and Laboratory
Methods Applicable to Overburden and Minesoils. EPA-600/2-78-054, US EPA, Cincinnati,
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Smith, M.W. and C.H. Dodge, 1995. Coal geology and remining, Little Pine Creek Coal Field,
northwestern Lycoming County. In: Proceedings 60th Annual Field Conference of Pennsylvania
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and Lycoming Counties, Northcentral Pennsylvania, Field Conference of Pa Geologists,
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mine spoil by sulfate reduction using waste organic matter. In: Proceedings American Society
for Surface Mining and Reclamation, Knoxville, TN, pp. 321-335.
Stanton, R.W. and JJ. Renton, 1981. Organic and Pyritic Sulfur in Coal: Potential Errors in
Determination. WV Geological and Economic Survey Circular No. C-22, Morgantown, WV, 13
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Stehouwer, R.C., D.A. Kost, J. P. Vimmerstedt, J.H. Beeghly, 1999. Reclamation of acidic coal
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International Symposium on Use and Management of Coal Combustin Products (CCPs), Vol. 3,
January 11-15, 1999, Orlando, FL American Coal Ash Assoc and EPRI, Palo Alto, CA, paper 76.
Tarantino, J.M. and DJ. Shaffer, 1998. Planning the overburden analysis. Chapter 5 of Coal
Mine Drainage Prediction and Pollution Prevention in Pennsylvania, PADEP, Harrisburg, pp.
5.1-5.8.
Waddell, R.K., R.R. Parizek, and D.R. Buss, 1986. Acidic Drainage Abatement Through
Surficial Application of Limestone Quarry Waste and Limeplant Flue Dust, Jonathan Run,
Centre County, PA. Proceedings 7th Annual West Virginia Surface Mine Drainage Task Force
Symposium, 45 p.
Webster, R. and Burgess, T. M., 1984. Sampling and bulking strategies for estimating soil
properties in small regions. Journal of Soil Science, v.35, pp. 127-140.
West Virginia Surface Mine Drainage Task Force, 1979. Suggested Guidelines for Method of
Operation in Surface Mining of Areas With Potentially Acid-Producing Materials, 20 p.
West Virginia Surface Mine Drainage Task Force, 1978. Suggested Guidelines for Method of
Operation in Surface Mining of Areas with Potentially Acid-Producing Materials. WV Dept. of
Natural Resources, Elkins, WV, 20 p.
Wiram, V.P., 1996. Unpublished notes distributed during a field trip for the American Society
for Surface Mining and Reclamation to the Skyline Glady Fork Mine, May 23, 1996.
Geochemical Controls
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Coal Remining BMP Guidance Manual
Section 3.0: Operational Best Management Practices
Introduction
Some remining Best Management Practices (BMP) are operational procedures that specifically
should or should not be implemented during mining. Other operational BMPs pertain to how,
where, and under what circumstances a certain procedure should be employed or to what areal
extent it should be implemented. The BMPs discussed in this chapter deal with a broad range of
mining practices such as: the rate of mining and the speed of reclamation, handling and disposal
of pit and tipple cleanings, auger mining, onsite coal stockpiling, issuance of permits with acid-
forming overburden, coal refuse reprocessing, and the scope of underground mine daylighting.
In certain mine sites the proposed remining operation is within a "gray area" with regard to
whether the pollution load will be reduced or increased. In these marginal situations, there are
operational procedures that, if implemented, can improve the likelihood of pollution load
reduction. These operational BMP procedures are generally sound environmental practices even
when the site is not considered marginal.
Theory
The production of acid mine drainage (AMD) requires three basic components: a sulfide mineral
(i.e., pyrite), oxygen, and water. If any one of these components is missing or controlled, AMD
production will not occur. In the production of AMD, pyrite is oxidized to form hydrous iron
sulfates (salts). Pyrite oxidation is catalyzed to a high degree by the iron-oxidizing bacteria
Thiobacillus ferrooxidans (Erickson and others, 1985). These salts are subsequently dissolved in
water and a hydrolysis reaction occurs yielding acidity (H+), iron (Fe2+), and sulfate (SO42~).
AMD production can be attenuated or prevented if:
Operational BMPs
3-1
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Coal Remining BMP Guidance Manual
Pyrite is not present in significant quantities.
The contact of oxygen with pyrite is limited or prevented.
ft The, proliferation of iron-oxidizing bacteria is prevented.
^.I';;; ,;';:: "i;'"'111; ฃ?."., 1. Kฃcoitact of ground water with pyritic materials is prevented.
The BMPs discussed in this chapter are based on limiting one or more of the basic components
MMt':'||f .': fffi^ ,'M' ' ,'in '', ^ ,"''',,'' ^ \'",.",!"""'"!,.,'"",','",".",'f "T "','"';' ..'',..,'','. '1,,, ,;"
:e Assessment _ rs : .^ _ . >iiii,i ;
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The mining operation should be reviewed in terms of whether or not the concurrent reclamation
is an viable option. Will the topography, type of surface mining, number of coal seams, mining
equipment allow for concurrent reclamation? Are there other factors that may impact the speed
of reclamation? If so, the question of how these factors be mitigated to ensure concurrent
reclamation should be addressed.
i
!^.ง part of site assessment, determination should be made of the amount of tipple refuse material
jihaj theremhiing will produce. This determination will require lithologic logs and chemical
l|, f^j| >^ I1!!] 'fa l^ll^sqs11 of IK coaf 'partings,' '"an3" enclosing strata! m|orma"tion'""sfipuld ""Be' provided on how this
material will be segregated and temporarily stored onsite. The type and location of an offsite
disposal facility also should be given.
Information on the hydrogeologic properties of the site should be obtained. The location,
direction,_and depth of auger mining needs to be delineated on mine maps. Depth of the
overlying cover also needs to be determined from drill holes. Using monitoring wells and
boreholes, the stratigraphic location of aquifers can be determined. Aquifer tests (e.g., slug or
l^o^stant-di^cjiarge tests) will yield information on the hydraulic properties (transmissivity and
1 I',,'! ,!!"",""!''!'"!'!, "i,,,r,n,', T !ฐ, !! '""!""!',!'"I',,,!'!!!' ''!'''' !'"!" '!ป,,'"''I"'!!, ',!,'!'I!,!,,,,!!,,,'",, ,'"l!,' ' !,,'' "!"!,!,!," ! ,,,!!l,T!!!' ! " , ,1 '',',!'"!!'!','!!!', !i !!'
hydraulic conductivity) of the aquifers. Water levels in the monitoring wells should be measured
', ', i
at least monthly to determine seasonal variations and response to precipitation. A literature
of spoil testing and/or onsite testing of existing spoils, where present, will provide data on
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Coal Remining BMP Guidance Manual
the projected hydrologic properties of the post-mining backfill. Analysis of the hydrogeologic
data will yield insight into the potential post-mining water levels with respect to the auger holes.
Assessment of onsite coal stockpiling will require information on coal sulfur values, location and
construction details of the stockpile pad, and determination of pad construction material (e.g.,
clay or other low-permeability substance). Engineering specifications on the pad material
compactibility, permeability, and stability should be available. Available space to construct a
treatment facility down gradient for any stockpile leachate should be demonstrated. If onsite
stockpiling is deemed undesirable, an operational plan to haul offsite the coal as soon as it is
excavated should be required.
Assessment of the additional overburden to be disturbed by remining requires that the overlying
rocks be analyzed using standard overburden analysis techniques as described in Section 2.0
Geochemical BMPs. The drill holes need to be distributed in a manner to ensure that the entire
site is characterized. The overburden analysis can be used to calculate alkaline addition rates, if
needed.
Refuse piles commonly contain areas where burning has occurred in the past from spontaneous
combustion or ignition by trash fires. If these areas are extensive, they can dramatically impact
the economics of the operation. The refuse pile needs to be drilled to the extent that an accurate
assessment of the amount of recoverable coal can be made. Once reprocessed, some type of
cover material that will support vegetative growth is required. Availability of enough topsoil or
a soil substitute to reclaim the site also needs to be determined. A survey of support areas
surrounding the pile will yield information regarding the onsite availability of topsoil materials.
A pre-remining assessment of the amount of daylighting that will occur should be performed.
This assessment is based on the amount of cover to be disturbed and perhaps more importantly,
on the amount of recoverable coal. Determination of the recoverable coal reserves needs to be
accurate. This level of accuracy is achieved by an extensive drilling program. It is not
uncommon for different sections of an underground mine to contain significantly different
Operational BMPs 3-3
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percentages. If these differences exist they need to be delineated. If the entries are
open, a borehole camera can also be used to visually inspect trie remaining pillars. The
lfamolM of cover can likewise be determined by drilling.
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M recent years, many mine operators have come to the realization that expedient reclamation
IIIIIB^ _ ..... liiir::!;-1"') liiiiiii uii!! :: iM"'-1: K.;. ''on ii'i1!,' iiiiii i" : i!11!1! i -:1-', IK ..... IIHI itniH^^^^^ " "iC" ..... :i!iซ^^^^^^ ..... I'ii < ; 'I'!; >. ซi!:. , iy" i "" r r ; "I >i> iri"*1 M' ir < I ' I ' in K ' i , I in i^""," *C | ,' 'i ; in," jR ^ ", v '
xidation occurs when the overburden is broken up and exposed to atmospheric oxygen. The
. . iiii!;:lซ^^
rocess of^overburden removal during mining breaks the rocks into clay- to large boulder-sized
particles, which increases the exposed surface area by several orders of magnitude. This greater
IBB1' BiHBBBVS'll
exposed surface area, in turn greatly increases the potential amount of pyrite that is freshly
!I,IT,,liri "IIliT ' f
exposed to the atmosphere and is susceptible to oxidation. A certain amount of pyrite oxidation
^^S expected and inevitable in the course of surface mining. However, when a mine spoil is
"' ' ' I '"
permitted to remain exposed to the atmosphere for a protracted period of time prior to
'r^rSdamation, accelerated and extraordinary oxidation of the pyrite-rich (>0.5 percent total sulfur)
rocks in the overburden can occur.
m
, , .1 1 li ,! . .hir 'iiiL.'JIi!: M, ','Cli1 ?!!,! li ,' 'u-.BIIJiJiillllB'llijil'Bulll'i'" Wi;' , ''"ll'lf'i'E!1"1!,1" ""'I'li!*'"/ , ''i',,,!!,!'i "1'i ;> ,,'i,, ', T ,:'"iiiiiilBMBPBL III1 liillllll". '''Bซ'":i
The scale and scope of acid mine drainage formation from mining cessations depends on several
K' Bill Htllliil'1!1!'!, H! iBTit1 IIAV "' < i ' ,11,' 'i,,,,' "* l||1"l|r "i,'!t t'
; ::;;;,:::;;:.;:::;:,-. i;;;;, .; ' ;:;;ป , . le,ngth of thie cessation period,
amount and sizes of pyrite-rich rocks that are exposed,
concentration of the pyrite in the exposed rocks, and
the form of the pyrite (e.g., massive versus widely disseminated).
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3-4
Operational BMPs
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Coal Remining BMP Guidance Manual
Other geochemical factors also come into play in the protracted cessation scenario. The chemical
reactions that create acid mine drainage are accelerated by protracted subaerial exposure. The
chemical reactions that can prevent or ameliorate AMD are attenuated by this exposure. If
present, alkaline materials (e.g., calcium carbonate-rich rocks) will yield alkalinity to water when
exposed. At atmospheric carbon dioxide (CO2) concentrations (mean 0.03 percent by volume or
0.0003 atmosphere), an approximate maximum of 61 mg/L as bicarbonate (HCO3") alkalinity or
20 mg/L calcium can be released into water (Hem, 1989; Smith and Brady, 1998). When
alkaline rocks are buried, they can yield substantially more alkalinity through calcium carbonate
dissolution. The release of alkalinity is governed by several factors, including to a large extent
the CO2 concentration in the surrounding atmosphere. Figure 3.la illustrates the relationship
between the solubility of calcium carbonate in water at 25ฐC and the partial pressure of CO2
(Pco2) in atmospheres. Lusardi and Erickson (1985) and Cravotta and others (1994) recorded
CO2 concentrations in mine backfills exceeding 20 percent by volume. A Pco, of 0.2 (20
percent) is capable of yielding calcium concentrations up to and exceeding 200 mg/L, which
yield substantially higher bicarbonate alkalinities (610 mg/L) than produced at atmospheric CO2
concentrations. Unreclaimed spoil will likely produce much less alkalinity than the same spoil
after reclamation has occurred and once the natural background levels of gases .in the vadose
zone are re-established. Carbon dioxide is produced in soils from plant root respiration and
bacterial decay of organic matter. Concentrations of 1 to 2 percent in soil are common.
However, higher concentrations can occur (Jennings, 1971). When spoil is unreclaimed there is
no soil cover to aid CO2 production and retard its escape. Exposed spoil is highly subject to
advective forces driven by winds, temperature gradients, and other factors, which permit the flow
of the surrounding atmosphere through the piles. With continual advection, near atmospheric
levels of CO2 are maintained within the spoil. Figure 3.1b illustrates advective impacts on
unreclaimed mine spoil. The relatively low permeability of a soil cover slows the rate of gases
released from the backfill, thus preventing the escape of CO2 once it is introduced into the
subsurface. Infiltration of atmospheric gases into the spoil is likewise impeded by the soil cover.
Operational BMPs
3-5
-------
ISiiW^^
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Mil; ii,, I; I "', "Ill'i ,n|,,, , ' ""; '1 ii'iiiili'isl',' ij ir,,, ;, , '''ii Jiilii'i ''! Jilii;,!,! Jii',,,,' i,',,',|:: ; i II, ''':'"'!"l "iiiiiii " , ป'II ri[,ii:i|, ,,,' ,,,,,1'iiiii I'liilQiMliiJil n'"!
':ijjj|ii" >{ jj':;' ]} lift Coal Remining BMP Guidance Manual
Hgure 3.1a: Relationship Between the Solubility of Calcium Carbonate and the
'i!''""i""' = '' : : ? fl?1'1 " iiip~ 25 sc (~rai;':'jmEiJ!iS' ^a*'ซ'-iป
":"~""
Figure 3.1b: Advective Impacts on Unreclaimed Mine Spoil
t
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Coal Remining BMP Guidance Manual
The reaction rate of sulfide (pyrite) oxidation and subsequent hydrolysis to form AMD is
generally much faster than the dissolution of calcium carbonate to yield alkalinity under normal
backfill conditions. With prolonged atmospheric exposure of spoil, this inequity of reaction rates
is accentuated even more. The rate-determining step for AMD production at low pH is the
oxidation of ferrous iron (Fe2+) to ferric iron (Fe3+) which is facilitated (catalyzed) by certain iron
oxidizing bacteria (Stumm and Morgan, 1996) that thrive under acidic conditions. Then, because
the Fe3+ will oxidize pyrite much faster than O2 (atmospheric oxygen) in a low pH environment
(Rose and Cravotta, 1998), the AMD production greatly increases once a low pH is established.
Substantial pyrite oxidation from protracted mining cessation and associated spoil exposure, can
accelerate the progression to this higher phase of AMD production. With accelerated AMD
production, any alkalinity that is released may be overwhelmed, resulting in a net acidic
discharge. If the backfill is prevented from reaching this high rate of AMD production, alkalinity
released from the spoil may be able to prevent or neutralize AMD.
There are some possible exceptions to the necessity of this operational BMP. These include but
may not be limited to:
Situations where the pyritic content of the overburden material is extremely low, there are
no disturbed rock units with any significant pyrite concentrations, or most overburden
samples are well below the threshold of concern (0.5 percent total sulfur). For example,
overburden associated with many of the coals in the southern West Virginia coalfields
fall in to this category. Table 3.la summarizes overburden analysis data from a surface
mine located in Logan County, West Virginia. These data are indicative of the low-sulfur
values common to these coalfields, but are not necessarily representative of the quality of
the entire coalfields.
It is possible that the application of massive amounts of bactericides on the unreclaimed
spoil may temporarily prevent the deleterious effects of a protracted cessation.
Bactericides can, for a time, dramatically slow the rate of pyrite oxidation. However, the
use of bactericides on surface mines in the past has been less than successful. Some
Operational BMPs 3.7
-------
Ill
Coal Reniining BMP Guidance Manual
II Ililiilll I "ill
i in in i n i in
success has been observed for the temporary stockpiling of coal refuse subsequent to
burial (Sobek and others, 1990). Additionally, the use of bactericides is expensive, thus
may not be economically feasible for many remining operations.
in in 111 in in
11 iiiiiiii II i in mi i
Table 3. la: Summary of Overburden Analysis Data from a Surface Mine Located in
,,, I,, ,1 i,,, i (i, 11 iiLogan County, West Virginia
l n ii1 n !| p in iiiiiiii ill 'i i lull iiii|ii in i n i in i in in n iiiiiiii i iiiii mi i n i i 11 in in i inn i i ii i i i n iiiii iii n 11 n ni i mi i i n n i i mi inn in i in in
IIIII
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Coal Seam
Lower Stockton
Lower Stockton
Leader
Upper Stockton
"A"
Lower Stockton
"B"
Coalburg
Total
Overburden
Thickness
( feet)
44.70
14.95
16.40
95.10
91.05
Sample
Thickness
Range
(feet)
1.30-15.00*
0.95-3.65
1.60-3.40
0.30-5.00
0.30-5.00
Highest Sulfur
Value
(percent)
0.10
0.09
0.06
0.10
2.21**
Lowest Sulfur
Value
( percent)
<0.01
0.02
<0.01
<0.01
<0.01
Median Sulfur
Value
( percent)
<0.01
0.04
0.03
<0.01
0.01
* The first 15 feet of soil and subsoil was grouped.
** This was a 1.45 foot thick unit and the only one to exceed 0.50 percent total sulfur.
\Off-Site Disposal of Acid-Forming Materials
I
I ilr iliilili SNI:
|||11|L IIIII 111 III IIIII II III III IIIIIIII 111 IIIIIIII III IIIII 1 111 III III I I III MM IIIIIIII III I 111 I I III 111 I III I 111 111 III II IIIII III III 111 111 I III I IIIIIIII 111 III I I I 111 111 Jill 111
Pin the course of a.remining operation, quantities of acid-forming rocks associated with the coal
(e.g., pit and tipple cleanings) are separated out and frequently stockpiled for later disposal
githin the spoil. These rocks include rocks immediately overlying the coal (commonly a black
shale or pyritic sandstone), parting or binder (usually a carbonaceous black shale or bone coal),
imrnediate seat rock (carbonaceous and/or pyritic shales or claystones) removed along with the
i 'I;,!!':' JPIII1' ,14:!'A ฃflff I,' 1111111" 1'lli'l! i: liOli,:<: Hi) 111!'!!!!! I, 'tint:' i':J "Siat t'i; >:: lui:'!t i, l";l illiti MittMMft. /,: WUftt,. WF?j!Uฃtt lUKJWKiL nil Ills;!. , i,: 'f,'Si, : i!'aiBi
coal, unsaleable rider or split seams, and other acid-forming materials separated from the coal
"-"a^iiiSpg loading out oFthe pit or during the initial coal cleaning at the tipple/breaker. See Figure
J! fit
jj(,;= ^iijijS Jbii;|or examgles of sources for pit and tipple cleanings. Total sulfur concentrations of several
i t'fi^tf*r!tti!F!limV(F"l>! Alii; i;!ii:r:-^ !;;;: K;,,! I
1111 "'"iii tKeserocks." Table 3".1'c"contains total suIfurvaTues forstfatlgraphic
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Operational BMPs
'III I 111 IP (I
3-8
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Coal Remining BMP Guidance Manual
sections surrounding the coal in an overburden analysis hole drilled on a remining site is located
in Westmoreland County, Pennsylvania (Appendix A, EPA Remining Database, 1999, PA(3)).
Figure 3.1c: Potential Sources of Pit and Tipple Cleanings
_
Channel Sandstone
with High Sulfur
Content Neaซ- Top oJ
Rider Coal Seam
rbonaceous Shale
.Upper Bench with
Shale Lenses
Parting
Lower Bench
Carbonaceous Shale
Remining operations typically occur on abandoned mine sites that are already producing AMD
from prior coal mining activities. Therefore, it is generally a sound practice to remove acid-
forming materials from the remining site and dispose of them elsewhere. Disposal of materials
that have been identified as acid-producers within backfill that is already producing AMD, has
the potential to accentuate or aggravate the existing problem.
Operational BMPs
3-9
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Coal Remining BMP Guidance Manual
(in i "in1 li ("in in
( Mil |l I IP 11 1,
! Sulfur, in Srjtratigraphic Sections Enclosing the Coal at a Remining Site
,4y, i.j U|[. in, Westmoreland County, Pennsylvania (Appendix A, EPA Remining
"" ' '
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iiiiiiiiiiii:!':'ijii::iiiiiiiiiiiigiiiiiiiiii|ii:ii!ii>iiiiiii.iiiiiiiiiiiii,il,
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Lithology
medium gray claystone
black shale
coal
grayish black shale with coal layers
coal
medium dark gray calcareous fireclay
Interval Thickness
(feet)
1
1
1
3
6
1
Total Sulfur
(Percent)
0.80
1.86
2.31
1.16
1.01
1.48
There are a few circumstances that would allow onsite disposal of acidic pit and tipple cleanings
l ittiilf
ing the potential to produce more acid) These conditions include, but may not be
' ..... !ป:>i ...... lii'i! i'!Si!::!l lAliliK ..... ! M'S1 UltfiV If l!llf ! P'iiiSliiil NIW:inWM'F>n' 'iffii ' ''KSItt Z!'!! .'.T.tl , Si'VifflfllPtl!' !ป .' I"* '. ill" If T
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I
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matenal. In these situations, the production of alkalinity will most likely either preclude
acid production (iron oxidizing bacteria do not thrive in an alkaline environment) or
;;; ...... -;; ,:;;;: .......... ; ....... ;,; ............... :;; ....... f .;; ..... ; ; ......... :;;, .......... ..... ......... ; ..... ;:;;; ;;:;:::;;;;; ;;;. ; ; ;::;;; , ; ...... :;; ..... ;:: ....... ;. ..... :;::;: ...... ;,;: ..... ;::;.;;... ..... ;;:;; ...... ; ...... . ..... [ ;;,:;;; ;;:.;. ..... ...... :;;;; ; .......... ;;,;;, , ::;;; ';;;:;:
werwhelm any acidity that is produced.
Nvfi" ' 'i-m-l HI (Iti'i; ป.fls iBt*!!!1! ..... as SB : . . s? ' ...... ' . a ...... m;R y. ..... ..... w : > , . i
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Sites where the amount of pit and tipple cleanings are relatively small in volume and
, fy IP ''illlllllllllllllllBfii'i1 IIIPIIIIII Jill HI!,! i;:,::iii,il lillKP id!!1 lilt'lPIIHIHH Ki"!i!! Ill :"; A, ' " fAซ, , ,,. , f? < - Z i ,
insignificant compared to the entire volume of the spoil. In these cases, the acidic
material can be specially handled (e.g., strategically placed, capped, encapsulated, etc.) to
prevent additional acid production. Care should be taken in these situations to ensure that
the special handling technique is physically viable (See Section 2.4, Special Handling of
AcidiEorrning Materials). For example, if the special handling plan is to place the acid-
; || -
fprming materials above the iwater table, the backfill should be thick enough allow^
jj&JiirM^ I t'.vr
ial placement well above the anticipated highest level of the post-mining water
.iaiJ ..... sal
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3-10
Operational BMPs
-------
Coal Remining BMP Guidance Manual
Auger Mining
Similar to onsite disposal of pit and tipple cleanings, auger mining during a remining operation is
generally not recommended. Auger holes, depending on the hydrologic system of the site and the
sulfur content of the coal, have a high potential to create additional AMD. Because remining
sites are usually already yielding AMD, it is generally not a good practice to permit auger mining.
Auger holes can create similar environmental conditions to those previously described for
underground mine workings, creating a substantial increase in exposed surface areas in
potentially acidic strata. Ground water entering the auger holes contacts primarily coal and
perhaps a minor amount of roof and seat rock. All three of these rock units are composed of
potentially acid-forming materials as illustrated in Table 3. Ic. At the final highwall, auger holes
typically are sealed with a low-permeability material to a depth up to three times the diameter of
the hole. The sealed holes are then covered with spoil. A large portion of the holes remain
empty, allowing the exposure and possible oxidation of pyrite. Ground water entering auger
holes will dissolve the salts created by the pyrite oxidation and subsequently hydrolyze, creating
AMD.
The amount of increased surface area caused by auger holes can be considerable compared to
exposure of the remaining coal at a final highwall. For example, a mine with a 1000 foot final
highwall, no augering, and a 4 foot coal seam would have 4000 ft2 of coal exposed prior to
reclamation. If the same site incurred augering, the exposed surface area would include the area
defined by the auger holes plus the remaining coal exposed at the highwall. If the auger holes
were 3.5 feet in diameter, spaced on 8 foot centers (leaving 1 foot between holes) and augered to
a depth of 400 feet, the additional area is equal to 549,750 ft2 or an increase in exposed surface
area of over two orders of magnitude (137 fold).
In addition to the increased exposure of acid-forming materials, the hydrologic system of the
auger holes is drastically different from spoil that is simply backfilled against a highwall. These
Operational BMPs 3-11
-------
ill- ! :** w 'Mi ...... itii ..... a ; '
Coal Re'mining BMP Guidance Manual
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inert in terms of AMD production because of the exclusion of atmospheric oxygen. Thus,
depending on the hydrologic system, auger holes can become AMD generating systems.
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There are circumstances wh^ere auger mining may be permissible at remining operations with
Jfttle chance of increasing the pollution load. These include, but are not limited to:
ii-jill! Illlllll 1 1 111 I I illlllll Illlll id I I ....... Ill I III P I n i |i|l|l 111 I I Illlllll I 11 llhll I i 1 In II I
If the hydrologic system is such that the auger holes are likely to be flooded and remain
so permanently, auger mining may be acceptable. Permanent flooding will preclude the
introduction of atmospheric oxygen, thus the acid mine drainage production should cease.
Watzlaf (1992) and Watzlaf and Bammack (1989) observed that subaqueous positioning
............ ................ , , ............. [[[ ......... [[[ [[[ i ............................................ ......... ........... , . ..........
of pyrite virtually stops the oxidation. Even if the ground water is saturated with
dissolved oxygen (12.75 mg/L at 5ฐC (Hem, 1989)), pyrite oxidation is halted by
' 'Si ^'S^cl&tffflersipA.,.. Augering below the regional drainage system will likely allow for complete
and permanent inundation the auger holes.
| 2 Augerihg above regional drainage may be permissible if auger hole sealing can be
achieved to a degree that precludes the infiltration of atmospheric oxygen and/or inhibits
.1 F ,P"i 1! I"'!'!!'!! !!!' I! I'MIIIIIIIIIIIIIIII ,,t\.\" , ..... laiuHfiii1*!11, .s < >ซ'' .......... jn ,, imiM ...... ^iiip''!^'''!!*!!!!'! ''iii,,,',!1 ซ uih
^'l.1^ ..... '""'I: ' " ; 1^ ...... ': ;;'";*;: flooded conditions are, maintained, AMD production should be prevented.
iii , . i ii . >; . ...... iiii .......
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Stockpiling of Coal
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,
Stockpiling of coal onsite for extended periods is not recommended. Coal is often the most
acidic material encountered during mining and therefore can produce the worst water quality.
ii in in i ii iiiii nil i i h i a
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Coal Remining BMP Guidance Manual
Leaving a large stockpile of acidic material exposed to the atmosphere and precipitation will
create extremely acidic, metal-laden water that can infiltrate into the backfill and foster
additional AMD production.
Often the least saleable coal is the coal with the highest sulfur concentration. This lower quality
coal is commonly held until it can be blended with a higher quality (lower sulfur) coal to
promote sales. This coal is the most frequently stockpiled and held for extended periods of time,
prior to sale. This coal also creates some of the worst water quality associated with coal mining.
Acidity concentrations in the thousands of milligrams per liter are not uncommon for water
draining from these stockpiles. Concentrations exceeding even 10,000 mg/L have been recorded.
Total iron concentrations frequently exceed 300 mg/L. If drainage of this quality enters the
ground-water system, AMD production within the backfill can greatly accelerate. Thus, it is
probable that more AMD will be produced under this scenario than would be produced if the two
sources (stockpile and backfill areas) remained hydrologically separate. Additionally, if stockpile
runoff infiltrates into the spoil, it may overwhelm any natural alkalinity in the backfill. The
alkalinity in the backfill may be able to ameliorate acid production from the spoil, but not from
the additional high-acid source. Exceptions to this BMP include, but are not limited to, sites
where:
The coal has an extremely low reactive sulfur (pyritic and sulfate) concentration (<0.5
percent).
The stockpile and associated treatment facilities are underlain by a liner material to
prevent infiltration and the runoff is treated to effluent standards prior to discharging.
The liner material, commonly an onsite clay, should be nonacidic and have a sufficiently
low permeability (e.g., less than 10'8 m/s).
A bactericide is used to prevent or delay the oxidation of the pyrite. This is only a short
term solution, and the bactericide may have to be reapplied periodically.
Operational BMPs
3-13
-------
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Coal Remining BMP Guidance Manual
TEe stockpile Is covered or otherwise sheltered to preveS the infiltration of precipitation.
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''i^]"M$1jgafflfiunt.pfjirne. the coal is permitted to stay onsite (e.g., 1 or 2 weeks) and perhaps
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>TJE Ihe. size of the stockpile are greatly limited.
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Consideration of Overburden Quality
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I St'!' ' Tiilfcll1!'1 'i',,If1 llllllllli', nr*< * it i tป.ป *i , . /***. fit / * ,1 \ I
s|li;i f ii|"",:|, ,"ii ii :IIVKT i*;"%;I.MI"; !:iiiii" , sm ; m> .T.TT", 4A".tปn i-' < s' ifr'if, "i* i*ป: ' i.ii^1 "ail' ! i*"ifปiHI iptti. ;f ! sra ซ^t.!T.*siซ swt;j'" , ui HUH , f.MKc iiiiii
';;;'_ *;;..'..'; ..';'"'', "'There are cases where^hydrogeolqgic conditions inherent to specific sites mil (with remining)
c^ pollution load to be increased. Permits for these sites are not issuable. The potential
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-illlllilll,,,): i1,;,''.;'!''' j; "i i i,1 'i ,,i,,';, ||!"!!i _ t , ,,i:isiiiiiH^^^ ii,,iiiiiiii|i|B |nin in1"; , ,,,,i 'Oi ii1;'1::!,; iHii,::: .Bi'ii:11 , jt1'!:!*',1,!! ,'.;,, is::,, lull' ii iii1 "i, n,:,!'',; ''it" ' ,111, ,ii;:|i|,: ii< _ :i: ,i"il;'' i,!,; .i,",,:,:,!,!::,',; 'Enni:!!
'.^nwi'^'i^. lii;!,,-" ii:fQr.5eclaiuming abandoned mine lands should not override the potential to increase the pollution
ill ii?f~:^:: "'' ||IoML,I1i^3ecisibn of whetihier or not, to issue a remining permit to some extent hinges on'"the
t:,:'i Siquality of the overburden material. The associated strata for some coal seams in certain areas of
!-.the,caalfields .are going to produce AMD if disturbed by surface mining. When mining occurs
" inn i ni': jinn "iriininjiinnniiini,!' niiiniininiinin n niiiiiiiin inn , 'in1 in , nil1:; "iin ,i',;i" >:! w /in ,,,n' i|,>;' i ',!'iii!::,:iii,:ii'::,i^ v> >,v
ni';,,i':iiiiiii::,':;v^^^^^^^^ !"iiiiiii!,iii|iii! "''ii'iw:! :ii|!!'':;r'' am- '-r'x '*! '.I" i >. f i'ii'i, "i tii:,; i,^, ' M'i r ..'ji"^"^^^.! rwi i 'i>isS, *.' ifist::. 'i'iiiii^ "iiiซi::Ms ซ:' iii>i ii - .'.'iilL! i lalii
ill
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unit in a coal overburden is considered acidic if the net potential acidity, based
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|iit jnas a good potential to produce acid mine drainage. The threshold for significant alkalinity
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'een empirically defined as a neutralization potential oF2'5 to 30 (tons per
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Operational BMPs
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-------
Coal Remining BMP Guidance Manual
thousand tons calcium carbonate equivalent) with a noticeable "fizz" (Brady and Hornberger,
1990; Perry, 1998). A fizz is the effervescence that is released when a few drops of a 25 percent
solution of hydrochloric acid is applied on sufficiently alkaline material (Kania, 1998). For a
comprehensive and detailed discussion on overburden analysis and mine drainage prediction the
reader is directed to, "Coal Mine Drainage Prediction and Pollution Prevention in Pennsylvania"
(1998), published by the Pennsylvania Department of Environmental Protection.
In situations where the overburden quality is such that additional AMD production is predicted
and BMPs will not effectively offset additional AMD production, remining should not take place.
In some cases, where it is economically feasible, other BMPs can be increased to compensate for
and prevent the increased acid-production. BMPs that can be used to offset the effects of acidic
overburden include, but are not limited to:
Alkaline addition based on the net acidity of the material. Alkaline addition rates above
the net acidity for the spoil are recommended to provide a margin of safety and offset the
inequity of the reaction rates (See Section 2.2, Alkaline Addition).
Removal and off-site disposal of delineated acidic material (See Section 2.4, Special
Handling of Acid-Forming Materials).
Encapsulation of the acidic material within an alkaline or a low-permeability material
(See Section 2.4, Special Handling of Acid-Forming Materials).
Physical ground-water controls such that either the water will not contact the acidic spoil
or the forecasted decrease in post-mining flow rates are more than sufficient to offset the
projected increase in concentration (See Section 1.2, Exclusion of Infiltrating Ground
Water).
If the proposed BMPs are sufficient to overcome the acid potential expressed by the overburden,
remining without contributing to AMD production may be possible. This evaluation will have to
Operational BMPs 3-15
-------
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v!1!, f.uป|t.Coa/ Remining BMP Guidance Manual
iade on a case-by-case basis. A significant decrease in the flow rate may be able to more
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; ; '^p.tnani.comgensate for a predicted increase in concentration. For example:
ate
a median of 300 gpm to a median of 80 gpm. The pre-mining median
111 III l|l| |!|!!'.' Ii:1 ;|' k^'i tf ^g|St^oiTcentration is 120 "mg/LJ which 'yields a median '"poliution" load''of 433
3?S''i!"'I;;': Sff *;^:f*m,i^^^iPl^i^i!!' Z%, py^^i6:^,', ^?& ^s. i^SS1, ,^?2!Ei?Le^, ,a,? .E,011!^!,
ini'i/I'liiiiiiiiijiiiiiiiini' ,:nivi^iiHH^ iiiKiii'i r '"'ii'ini1,, .in: ii, i'm; |i;ii!iii, "'iini,,:1'!!! iih, piwiiiiiii n ;i' .'lijT'Hii i 'i iiiiiiiiiiiiiiViiiiij:ii|Vr,iAii<'iiitM^^^ ii: liiivffiiiliMP'ii'ii,'1!1 ', cmi'-siiiiii 'i,, 'I'^iH'W'";!!'!':''!,''!,''1 i Ah'ii: , i,'i,"1 .ii'in n 'iiiiiiii,1, i
iCj will be disturbed by the dayjighting. This scenario could accommodate an
i ,., ,_ , ,,, , _,,,,, - iiincrease_iin the median acidity concentration to 450 mg/L without a concomitant
"' ! :i: l!l:;'! "A': ' ? " I '"acidity load increase.
;, , ' I
It is recommended that remining permits, where the contaminant concentrations are predicted to
| ;^jbe increased^ either be amended to include JBMPs to prevent additional pollution or be
without truly
f':!!!'' il'.'^"'!!^^!^ฎ^?!1^ ^e Pฐ^^9ฐ ^ฐ^ m,ay งear %^v^y P,11 *งฎ Snal permitting decision.
[I, j y gCoff/ Refuse Reprocessing or Cogeneration Usage
|,|i;:,:,!,!'jiim.,1 ' *4, *::>^xf'Miffievm ^, kH | , i i f, M, ,S, ,,^ ,, , ,, ,, ,, ,,,, -,
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I Remining operations where abandoned coal refuse piles are reprocessed to glean out the
!"!!!!!!!!"" "i:",!:" :,!!!! F!!111'1"'"'"' !!' " I!!!!!!!!!1"!!!", !!'',!,' i ! I:1!!'',,!"S!1!!,,, ~f, rr ฑ, f- Vr
I ^remaining coal or the entire pile is excavated and hauled to a electricity-producing cogeneration
; ........ i:!' ..... ':::, tm ~, mit >" -* i mr-( .'
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I S i'i'1 BbJsnt are almost without exception highly beneficial. These operations remove a significant
, , , , iifiiis^ ?&mii$wiiHmmmMw^w&-wn
I portion of the acid-forming materials in addition to regrading and vegetating the remaining
I llli.t'1, iiaHiiiiiii isiiiB^^^ iiiiu^^^^ !ii,,,::>!iiiiT^ii|iin^^^^ ,,i";iic,,ii!|i 'i::; lipiaiiiwfii'iK liiiinatiiiiiiiit^ i!i(!i:ป^ :wis1 vtifttf ป-, :ui)Jifftfafit
11,1,, ,"",,'" ,"'*l,,,l ii!, I,,'" .I,,,, I' Iป , ,1" ,,,, ' ' ilIIII',' M,,*!! ,1!' ,,l! III!!"'. ~!r!,, liiilliriun !!,^, ZIII ,17 'I'! ","11 'Z,!!! I, ,! N" Ihl,,! n,ป! "I ,' ,1 ill,'!!,! '! J !!,!'"""!" ! "I'.!, I'!'"' II lii,,,, I, .I! "m I!!! T"! I11",!! ilZil, i,7ซ .I'! Z",^' 111,,!! VII, Ii!,!,,! w^ ,! ,i', u "1,,,,' , ",nL!,,I,,, ',!, ,,! " , ,,"!!"!! 'I !'!,":,!!! I, !,I,
|H!''KBGtK^^'VTi9ateriaI to inhibit water infiltration. All reprocessing activities work to greatly reduce, if not
I ;:[; .i'iHl fliiii:'llii ij'',' : ,' in : ''ซ!ซ B, ,''ป ' i> -ufi ~>( :,' ' ,!" i ".:; ' u .i*
Eliminate, the pollution load.
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IlilTr iFl'iFllillil U1 'Ignliliiliri ;il,iiVปi|liiwi,,,l !i,,F nl|:i|,l,,,i jii, ,1:111' ,i,, ,,"iiir ;ii,,,lT'| :ป, :ig,,r:r!:,iiiir,|inl n, I1", T , '!: w1;:!!,," !,,I'^-iiiiKIS-''''!^^'!.!^!! "vi, ป iiiiiiii|ll|tliii<:l; '' i'1'1
andoned coal refuse piles are common in areas witii historic mining. In the past, the coal
, U ill, i, '< !"!, .1 ' i:| Hll,,,"1
I
tyiiii' i>, I
cleaning process was not nearly as rigorous or technologically advanced as it is today and large
i
piles of waste material were dumped at the surface. Older coal refuse piles tend to have
I commercially recoverable quantities of coal or enough burning ability for use in newer
"^j:^' , I technology such as electrical cogeneration.
,, , , ,,, , 3-16
iP!1! '!!, " i Illllll IN 1 IIIII III IIII il 1 111 1 1
1 ( i n I i 1
Operational BMPs
!|l II1 1 1
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Coal Remitting BMP Guidance Manual
These piles, some approaching 100 years old, are still producing AMD. The coal and refuse
material (e.g., carbonaceous black shales, some roof and seat rock) that comprise refuse piles
usually have a significant sulfur content (> 0.50 percent total sulfur) making acid generation
almost inevitable.. Acid production is additionally facilitated by the fact that coal refuse does not
readily support vegetation. The acidic nature inhibits plant growth and the commonly dark color
generates considerable heat in the summer causing heat toxicity. Without vegetation, infiltration
of atmospheric oxygen and surface water is virtually unimpeded promoting continual acid
generation within the pile. If these piles can be reduced in size and amount of acid-forming
material., regraded, topsoiled, and vegetated, the volume of acid generation will be reduced. In
the case of refuse used in cogeneration, the entire pile is commonly removed for burning, and ash
from the cogeneration plant is frequently returned to the site. This ash, depending on the type of
cogeneration plant and original sulfur content of the refuse, may be highly alkaline.
It is not uncommon for refuse piles located in the bituminous regions of western Pennsylvania,
eastern Ohio, and northern West Virginia to have rates for recovery of coal from coal refuse piles
exceeding 20 percent. Similar values are found elsewhere in the coalfields. Some positions
within individual piles have reportedly had recoveries exceeding 50 percent. Much of this coal is
economically recoverable using modern coal processing techniques and many of these piles
(anthracite and bituminous) have overall burning abilities of several thousand BTUs. This refuse
is commonly burned in conjunction with oil, natural gas and other materials to produce heat or
electricity. Because of the relatively high sulfur content, limestone is frequently burned with the
refuse to aid in desulfurization of the smoke stack emissions. The ash created is commonly
alkaline and can be returned to the site or used at other sites to add alkalinity.
The operation of reprocessing performs several functions that work toward reducing pollution
load. First, a significant portion of the pile, hence acid-forming materials, is removed. Second,
refuse material is crushed to a much finer particle size and, when replaced, pore space percentage
is dramatically reduced. Thus, water will move through the piles much more slowly and much
less water will be stored. It is also more difficult for water to infiltrate initially. These piles
Operational BMPs
3-17
-------
iiiii^^^
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Coal Remining BMP Guidance
are regfaded to promote surface water runoff and reduce infiltration. The piles are topsoiled and
., I vegetated, which, also reduces surface-water infiltration and inhibits the infiltration of oxygen
into the pile. In other words, reprocessing has the ability to reduce the rate of acid generation,
reduce the amount total amount of acidity generated, and reduce the discharge rate from the pile.
'"'Use of refuse giles for cpgeneration has the potential to completely eliminate acid generation
I JIM ii',1!!'?! ; ' "I Iilllllli1.,.;' Kill. Ml I"*" UMiHsni ::li!lill III!f .I'S/i'll'I ) i,.:,:':!'! lillRlli iiiii'll' I"! 'VHK ii 'liii::.:1.!'1 i': Km-'fi, 3 Iliiiillll'," Urtli.M'1: ,. '" ni'iiiill: j:!!.:'!.);].: : I 'fill!.' ," 'ililloi,:' is i''" Fill .""!' Pi:' 1 Il llin^ lillll B": ii'lll I
"3. Complete removal, removes the acid-generating source. Additionally, if
c,o,phus.tion,...waste..(CCW) is returned, the site may begin yielding alkaline waters
|ing acid generation elsewhere in the basin from other piles not economically remineabje.
JRiliiii'iilPRRiRiRIIIIPP'liiii 'I RIP
I .pili'l1!1 . ,1'RRRR .:
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"I Ri'RRiR '" i:Ri!IR RR!iRi|"'R "i,i IliFIIIPhifi.i.lJillJ1!',.ill.!"',''',' 'iRRRI IIRR ^IRRRR'ii PUI ,'jili, RiRPRRRRR'^VRR RRRR ",, Riii, RRR R 1
11111 RRIIIIIRIR . ll'i' PIRR! " If niR'R lilllllil R R RIRiiIRR RIRPRRRPRRIIIIIR
limitations exist for coal refuse reprocessing or cogeneration use. However, the
i.| nllRiR 1'i' .RillJli,"1 .l|', Jllllllili, JRPPR',,,, 'ill |||||||||l|i,'l: RPR1 RR RRRpi Ri RRR i n PI*, R'PRnRRRi ,i R' R ''i R R RJII ! IRRIR'Ri' 'rlRR ' Rl'iii [ R RRIRIPlR. ||l|ซR| RnRPlPilP' ! Ri|'R n R,.,. pp,ip l|ii||||||||||||||li||||||l' "ililll Rll Rll RP* Rn,l IIIRRI !l II i n|R l!.' R RIR'i:", IJ RIlRP. 'Rm! , PP.RRIRi.RIPRiRRPII i ,1,'"'" '' RRRR "I"' '.'i'" PR! RUHR: 'PR RRPRIIIIIIIIIIRji Jill
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ial exists that if a relatively stable (physically and geochemically) pile is excavated, acid
e reactivated or accelerated. The sediment load could also be increased, ^
tgmporarily. In the case where CCW is returned to the site, care should be taken to ensure that
:? "! ! ;;;;" ' ' ;:=;";'";;;i ":;:j;'- " : -';:;" "::;:;; ''" -:;;;":";l ;;;;;;:" j- :~ ':;"'";: " "'' ';; " '";" ': -;"::":;;I ';:; ;; '- =;; ' "'"" ;;1''";:;;=! '' ':= ;; -';;i ~~'1 "';;; ;:":" -""""; ;" ;:
^1=?-' -''"I-? higher amounts of trace metals will not be liberated from the ash. Testing of the CCW, for
iUII'ijfS! ' s!VrE^^fple by using me Toxicity Characteristic Leaching Procedure (TCLP), should performed to
! ' I " '
establish the potential for trace metals leaching.
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positive results hi terms of reducing pollution loads. Daylighting can work both physically and
111' i'lli III' llliBi ill'' ui ill ill illil 'ill1 Itiilllll'l, PR PilRIPPIIil;, IIPilllPPRRIIIIIIIIIIII IP"' RIIPPPPIIIIIIIIIIIIIIIIIIIIP,'. il 'illPllllllilllllllllll Hi .1 '"'IliPP' tlRPRIIIII i,1"' PRซPP[JR' P1! J,|||IP||RI|IIR||PIIP1I, J fl PRIIIII' illllllllllll" PRIP'RIll, |l|l;|iป|i II1 , 'iii|'l,i ",,,||||,||.' 'ilB.lll1 IJIIIIIIIIIII',' .'I). ,pi "Jl":i:iilli ::|i|".| T. . !' "I IIJ'PPPIP'P,; ''", Jllllllllllllllllll' Mil'' 1 Illllll. ' III nil" .ill!1'' ,11 Illnli'llllllllllllllllllllllllll ill ,<(' 'illljl.ln.iiil!1 ii'Jil.HH "illi,' III lllllilllllPI ll.:"Pilil PlillPli II P"ซ'", f l||lil I
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:dcnemically to effect a pollution load reduction.
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reduction of potential surface water infiltration zones. As previously discussed in Section 1.2,
'Ilii:'1''1 : Illllllril' 'liiilH .liJH ' 'I^IIK iilltl'li...!:. ;'.: .'IKi'i'lLI ": i:l illllll .ill' 1111 i'i". :."l'l.'' i! "t.' 'i'li'l:.:!,>!' ["iniRTi"111 .'i!' 'If "'S',"i!!!'- > IBIiiliilt.m .'IIII1IB ' '! ซ!: liXilf' i' il'M'll I'MUlii',','.'!" iililH ,,'i :f.,i.l {,!' lillll"',' ,:,:B:,
daylighting tends to eliminate large portions of subsided mine sections where considerable
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a . -; ground-water hifiltration into the mines occurs. The reduced infiltration rates in turn
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I:::::::,: ^^, R r;.. ^fecJUtete reduced nloads. Surface-expressed subsidence features, such as ^exposed fractures and
;nd Jp fipJlect surface and ground water and divert it directly into the mine. When
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-------
Coal Remining BMP Guidance Manual
surface mining eliminates these subsidence features, water infiltration into the mine is
significantly reduced. Daylighting also eliminates substantial void spaces that serve as mine
water storage areas, which tend to facilitate a more continuous source of lateral recharge to the
adjacent reclaimed renaming operation.
Daylighting dramatically changes the ground-water flow system from open conduit-type of
underground mines to the double-porosity system exhibited by mine spoils (Hawkins, 1998). In '
underground mines, ground water, once it has entered the workings, tends to contact only seat
rock, roof rock, and coal. All of these units are commonly sulfur-rich, hence, potentially acid-
producing (Table 3.1c). The data in Table 3.1c is from a mine in Donegal Township,
Westmoreland County (Appendix A, EPA Remining Database, 1999 (PA(5)). The strata that the
ground water will contact in this mine, based on this drillhole, have a total sulfur range of 0.574
to 1.637 percent. In short, everything the water contacts is potentially acidic (i.e. <0.50 percent).
Once in the underground mine, ground water tends to follow the path of least resistance, which is
through the open void areas. Therefore, the ground water continues to contact acidic rock units
until it exits the mine via a discharge point or infiltrates into other ground-water systems (e.g.,
adjacent surface mine spoil or undisturbed strata).
Once surface mining and reclamation have occurred, the ground-water flow system changes
dramatically, and the strata encountered is reflective of the entire overburden quality. Rather
than only encountering acidic strata exposed in the underground mine, ground water will contact
strata in the spoil that can be potentially alkaline or acidic or relatively inert. The amount of each
type of rock intersected by the ground water is directly related to the volume of the material in
the spoil, and to some degree, the mining and reclamation methods. Daylighting operations may
need to have special conditions to require mining to a predetermined overburden thickness to
ensure that a sufficient amount of alkaline strata are encountered and spoiled.
Operational BMPs
3-19
-------
in n i linn ii n ii n iininni n
iillllli 1 ill III I (11(11 II ill
'Coal Remining BMP Guidance Manual
Table 3.1c: Coal and Enclosing Strata Sulfur Values (Appendix A, EPA Remining
Database, 1999, PA(5) hole OB-5)
IIHII! IB^ailEla1:!'' '&3fX BK"!I IIBI T Ilil'lJli If1 IH !!,li!l
HW FiWWUPT* '"': n, IIIIB'i;' IfM * 'WIM
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iiion't fit ,i pun1: ^ii'iiiifiH'!''''!!!!; m' UK
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;I9^^^^^^^^^^^
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Interval
95-97
97-98
98-101
101-104
Lithology
light gray shale and interbedded
sandstone
medium dark gray clay shale
coal -Lower Kittanning
light gray fireclay
Total Sulfur
(percent)
0.344
0.574
1.637
1.201
;il ฃS^H:E Table 3. la summarizes overburden analysis data from an acid-producing underground mine in
*"'";;;; "'Aimstr=ong';County, Pennsylvania, on the Upper Freeport Coal. The data illustrate that the coal
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M ^"'^F itself is the acid-groducingrock unit, with total sulfur ranging from 1.60 to 2.78 percent.
' " !Ji!iiiii!n I
iU remove most of the coal. As is common with most daylighting, some of the coal
niii ii ijjiijii" Hi" a nnir
iini ..... !!::!ii ...... i'l'i iiii
hand, the overburden itself exhibits relatively low total
iv if :l!lA l.!l .iilllB, ttVMWLM!!'' ! ii I.E. ..!l!lyE.IP^^^^^^^^^^^^^^^^^
smfur values (i.e. <0.50 percent). Total sulfur in the overburden ranges from 0 to 0.32 percent
.
i!1!- "
iiihaiuiiii^iiiiaiiaiiiiiii; PI IB
. 0.10 percent. However, the overburden does exhibit
' severalf zones" of stg^iiic'a^alkalme1 material with ne^|Jfa||2atio1ni potential"(NP)' of up to 209 J'
tons of calciuin carbonate equivalent per thousand tons. About 22 feet or 26 percent of the
I
1' rl ; i* ISKs. 'atenal'" is bagEIy 'broken up, ' mcreasing "the "exposed "suJf-^e" ...... '^a j' "and' it "is mixed "to ' some .......... " .................
degree in the gacj,;5|| Groun5 water should contact each stratum to a degree similar to the
volumetric content of that rock unit. Therefore, in the aforementioned site, roughly one fourth
(26 percent) of the time during transit through the spoil the ground water should be contacting
;, I i
=;:-1=ii'^='-"l'ii'i"':.t"^;^ne ...... strata. ............. Most of the, remaining time, the material encountered by the ground water will be
1 i~is|ง|iy,ely inert in terms of acidity and/or alkalinity production. Thus, once mining has occurred
wiater"wni contact 'very" little acid-producing ...... ma^j:a|s_
Mus'ixates
I'l '(ii'lllUI HIIW 'L 'ill
how daylighting has the potential to greatly improve the quality of the material that the ground
|j;SB -f ^
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3-20
Operational BMPs
-------
Coal Remining BMP Guidance Manual
Table 3.1d: Overburden Analysis from an Acid-producing Underground Mine in
Armstrong County, PA (Appendix A, EPA Remining Database, 1999, PA(6)
hole OB-4).
Interval
0-1
1-5
5-10
10-17
17-20
20-25
25-28
28-31
31-33
33-35
35-38
38-40
40-42
42-45
45-48
48-51
51-54
54-56
56-58
58-61
61-64
64-67
67-69
69-71
71-74
74-77
77-80
80-82
82-84
84-85
85-88
88-90
90-91
91-93
Lithology
soft light brown sandstone
medium light gray clay
dark yellowish brown sandstone
pale yellowish brown sandstone
dark to medium brown sandy shale
moderate brown shale
medium gray shale
pale red to grayish red shale
moderate yellowish brown shale
moderate yellowish brown shale
pale brown sandstone
pale brown sandstone
pale brown sandstone
dark yellowish brown shale
dark yellowish brown shale
dark yellowish brown shale
dark yellowish brown shale
dark yellowish brown shale
dark yellowish brown shale
medium light gray shale
medium light gray shale
medium light gray sandstone
medium light gray sandstone
medium light gray sandstone
brownish gray sandstone
medium light gray sandstone
medium light gray sandstone
medium gray sandy shale
medium gray sandy shale
medium gray sandy shale
coal
coal
medium gray clay
medium sjay clay
Total Sulfur
(percent)
0.02
0.02
0.01
0.04
0.16
0.04
0.14
0.02
0.02
0.03
0.00
0.02
0.02
0.04
0.00
0.04
0.00
0.02
0.02
0.18
0.14
0.10
0.06
0.06
0.04
0.06
0.02
0.14
0.11
0.32
1.60
2.78
0.11
0.10
Neutralization Potential
(tons per 1000 tons of CaCO3
equivalent)
0.47
3.15
5.29
9.63
6.41
8.77
3.73
3.50
40.1
44.07
29.85
29.85
209.70
4.66
7.00
82.05
125.82
7.46
5.60
3.96
16.90
16.21
8.74
11.31
77.19
31.61
44.37
12.82
3.38
9.09
0.82
0.12
4.20
10.73
Operational BMPs
3-21
-------
I
Coal Remining BMP Guidance Manual
il nil I I |i|iiซll
II I HIM I IIIII
11
JIIL
"''I1 |,||EI|li||l|||
"
minei js not daylighted, the remaining underground mine entries need to be
, il31l MEJ'ffiK: si 'MF.Bir:::!"? !*;ป:* Wto.''')!^ i>f;>Ks" .it! immmwi:, ^im'mmfmK.iiiiiE: :::a I
^injand[^Ae backfill and to preclude oxygen infiltration into the mine entries.
"
111! I IIIII 11 I IIIIIII
I IIIIII IIII IIIII IIIIIII
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; i|.i:!\.il;ip
, . .. Hi'
Daylighting underground mines does not always yield a decrease in the pollution load. The
[[[ [[[ i
predicted decrease in flow rates and the change in the ground-water flow system, as described in
Section 1.2, can be offset by the increased exposure of highly acidic overburden material to
atmospheric oxidation and subsequent contact of ground water. This situation could in turn
produce a higher pollution load (acidity and/or metals) than previously existed. Reed (1980)
................................ ...................................... . j
observed that daylighting of a underground mine in Tioga County, Pennsylvania, on the Bloss
Coal seam, increased the acidity concentrations. In fact, he observed a direct relationship
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between the amount of daylighting and the acidity concentration. The overburden of the Bloss
Coal was "mostly shale containing pyrite" indicating the potential for acid production. However,
this site js an, exception, rather than the rule. In most cases, daylighting successfully decreases the
pollution loads.
...... Implementation Checklist
*
The efficiency of these operational BMPs is related to a large degree to the restraint of certain
,;_ 777;-'.^ ~r.=^VVll!|5ป^eip_rpmqtioni of others,^and effective management operation activities. All have the
iii
; ^l^jcific goal of reducing the polhitipn load; however, these BMPs are somewhat diverse in
iiiiiiiiiiiiiiiiiiiiiiii" ' '' i!; it ,1; niii'lnui T :' .!' iljiiiiiiiiiiiiiiiiiiiiiiiiiiiii:''" '' , .uiiiiiiiiiiiiiiii ', ! iiiiiilil ,,i jiii!!!S!n'i 'liinHli'iikU'i'h n iiiiiiiidwii i: ! ' ป iniiiiiniii'i "; ' ' iiiiih'ii ; liini,!' ' >'ii i "iSiJi" iiiiii' iiiiiiiuiiihi j : , i t\ 'i! '! i ,ซ, MJ Iiii '< -T ' . , i: ;,', i.C li t>\ iJ ii' "''ihiiiiSiBi1' ii m i';iiiiiiiiiiiiliiปi!i: ,* i ''', ;< i ii'1 ' ii! ป'" l|i|!i!,ii"!i||1 w i "'iv v ,iiiiiii"if ' >',','<' liwiii1' r: j" ' 1 ..... , , < ii ซ iป! 1 ป ' i 'iTJiiiiiiiiiiiiiiii'., iHiiiiliiiiiSi'" ,
j^Sfds to how this goal is achieved. The following list includes some recommended
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' ' " " .' I . ', ..... . '; ill... 'ป: .:" , 1 1... : , i'.'IJ; i;|' ||lป ;' lifill ;l ;"; ii1. I" ' Jl. ll.f |if! Iiii. 'l'*"! Q|I|II ' lii.i 'ii I11! ! liMi 'i ..ป. i:||| '"'' n 'X ' : , n ii1 : k . ' i .';.||il|!; '"I "li1 in / " : .| ''' .ill ซ( ijAI1 ii , , ill,1 I' ........ I , ; 111' I1 ' .'I iii ' :l / ., ' /ii! ;'" ( ...... ui|; iiii '!"".;< ', ' , . , ;i|||.i ' ', '> '4l ' ' n I1" , ^ .illi'i11 ' H1!!^
iii" IS ..... S: if^iii '' !ง : ii;if ii f iiiiiii!' ' flf^j^: ' \ !|i| ;-',:;i: '; il: j'.itfii1^^1' iii^ii^J"; '\ ..... I ;; ; tli';i:'.,'. ' I1 ''ft ': "iitifif t'tlf
imn g and Cone urrent feclamation ............ ......................... '
.' '.ijijilla;, ih . |lE||U||i j j. j Tl; p: i ii: ji|i|||| II t 'l ,, p1 ' i n
:M!i ....... irtif
Minimize the amount of time the spoil is sub-aerially exposed.
I
I '.:.;':.]g:egrade and revegetate as soon as possible after coal removal.
>'ฃ il1' ' ' ' '-"' ' i'111'11'''1' 'll|l|! "
I hi?>['!'): m1 aiSi!1 .;"i>:!i'1
r "i, ! ;: , -,"-" 3-22
Operational BMPs
"1 'i'i'" i ' ' < 1'" ' i 'i i
I |.::M > ' ."-iiilW'f i:J:L-.'.,|.i '!;i-i.H^
I ป
.. ,, ,
ii i v. ' ::; , ' ...... ^-ivj- n1 ซ i;* is ii :J ..... i . ' . P ' ": ' ' ' 'i "i1 i1 i. ' i, '. "i"-'
..
-------
Coal Remining BMP Guidance Manual
Off-Site Disposal of Acid-Forming Materials
Note high-sulfur strata and segregate it.
Stockpile and haul acid-forming materials off-site.
Auger Mining
Avoid auger mining above water table.
If augering is necessary for economic reasons, be sure all holes are properly sealed to
preclude ground-water movement and oxygen infiltration.
Stockpiling of Coal
Do not permit uncontrolled drainage.
Cover or line under the stockpile to prevent drainage.
Set maximum time allowed prior to removal or completely preclude stockpiling.
Consideration of Overburden Quality
Determine the net acidity/alkalinity for the entire volume of overburden to be affected.
If the overburden is acidic, other BMPs should be employed to compensate for the
negative impacts of disturbance.
Coal Refuse Reprocessing or Cogeneration Use
Regrade and vegetate to promote runoff and inhibit infiltration.
Where possible return alkaline coal combustion waste (CCW) to the site.
Maximizing Daylighting
Eliminate as many of the existing water-infiltration areas as possible.
Remove or decrease contact between acid-forming materials and ground water.
Mine to a point where as much alkaline overburden as possible will be disturbed.
Be certain unmined entries are properly sealed.
Operational BMPs
3-23
-------
II: I "'lliv','1 ' .I'1!1,1!1 liHHIi'ii'1,1
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,. ~j^ogi_SsMining BMP Guidance Manual
' 1'
ification of Success or
!' ,;ป H,'"',
ili^ij,,, l^jiฃ]> i|||]!!;]!|
.verification.ofproper implementation during remining operations is crucial to
i; ,i SM liiiiii'I ,-iir: ii ~'i i '.li i' jit' i, v.i i ,ii; sti M,'; ji"!" i,m&s:; ii iiiiiiiii :,;wrjireikrWii:; i;" vie:is'"' i, > **.' tsmt 'vm mป:" in11
, , , , , .
effective control or remediation of the discharge pollution loadings. The importance of field
!!: Verification of all aspects of a BMP cannot be overstated. It is the role of the inspection staff to
,. 'Si
enforce the provisions outlined in the permit. The inspector generally does not need to be
illlK ''l^S i'l lilllll^ I I1!"! 'ill',:1!,! : -'til,, !i I , 'Wi,' 'IIHS i'W^^^^ I"; .1 k ' iiir'v:',,' iHli liilllNll!':! B; iiiiiH^^^^ ' iiililllil'iitUFl'iH .< Lliil :i I*', "I :|< I '.-iili!.:.!'!),',1,;!!: 'ii ;ป:ซ(!"ill1
IIH ' , / ill, I""1!!'''!"!1,1'"!" ''illi1':!"!!/""!'')!' ti'' 'Illii'S III' ''IS 11 "I1'.'1, iilllHf i!' ..... rii ..... ii::'::1'
, HillllR',, ' |. Iv ilKl
During rapid mining and concurrent reclamation, inspection staff needs to verify that the site is
reclaimed shortly after the coal is removed. It is possible for permits to require notification by
the operator of certain reclamation phases and/or require certification by an engineer or
registered surveyor that the reclamation occurred within the predefined guidelines. An inspector
'i' i'TII" P",'!!! ' , l,i,,, J'lPimif11;~ ii^Mllli'l1 Slill"1:!1,:
!!!! ji:1,;,1' JUILIIHIIIIIIIIV jiii'ifiiinun nil ฅ
, liili'iVIH1"" "! I :, !i ' Wlil! 1111
should be able to visually assess that reclamation is occurring concurrently during each site visit.
lllliii? '
I liiilllllllllllir jilliiF*;;,!!'!.,
i!iiii:!i"
'lilvilij1'
ii;s:ji
; i,
IJli!'i
II 'i
os|pit and tipple cleanings can be verified using a lined stockpile area and review of
'L! ' ^^^^^^^^^
\ ',"ii;jf"";,, Jiiilirne periods, until it is hauled to the waste disposal site. Copies of the weigh slips from the
I
,
waste" disposal site and an estimate of the amount of material stockpiled should be submitted to
:;: ...... ::: "";;;; :i^i ; ~; ;.'." ,:.;.' . :,: ; " z, ,i :: i: i ~ 1 11, ; ' ....... ; ..... ; ; , ~ ,r,r,; , : " ....... :'.". '. : ............ iii ' ' ,; " ..... ir ri ; ..... ";z , zii: , ,i : ~j ;, ,; ,; ........ " .;." ~.".~~. zi .", , ;;.: ..... z, iz ....... ii" ;
inspector for comparison of the amount of material sent to the waste site to the amount
, ..... f'iil'J!! .....
s!oc^R_e<*- J^e, amount ฐ^ mat?"a^ stoc^P^^, c^^e ?s$x$!*ted from thei dimensions
' ซ' ฃ&?,$ฃptfe oir"5o"m" company-supplied records. The'total amount of refuse'to'be removed""g-om"
the sfle can Be estimated from the overburden analysis and volumetric calculations based on the
strata "tniclcness and the area mined. This estimated amount then can be compared to the total
I.." ; '.,,;:, :.,:..! ....... .,,; , iiii|,:;ง|lQunt ..... that ..... wa,ง actually shipped off-site. The inspection staff should also observe the
' ' ' ' ' " 1 ' " ' '
I'1:, 1! ...... '. ;:!]!l!1!)i!!i ! ......... ;; '
I mil" i ' mi1, i|'l i:1
I' lillllll' 'iiilil IliilllliiK^ ili'ilia^ Illin'l >>. .'IKIEi'''!'! i -iiii 'I't'l. I']:!'' 1 [rii'MI'i' i "111 !l|!i',l .i);!,!"!!" :!'j,!l:
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Coal Remining BMP Guidance Manual
Verification that no auger mining has taken place is relatively straight forward; either it does or
does not. If augering is permitted, affirmative proof should be submitted that all of the augering
occurred below drainage and/or the holes were sealed as approved. The determination that
augering is below drainage is initiated during the permitting stage. The operator should submit
hydrologic data showing that the coal where the augering is proposed is below the regional
drainage. Data needed for this determination include, but are not limited to:
pre-mining water levels
stratigraphic location of aquifers
transmissive properties of the aquifers
dip of the strata
projected post-mining water table
anticipated post-mining recharge rates
the location of potential nearby dewatering sources
the location and relative elevation of adjacent streams
specifics of the auger mining plan (e.g., location, direction, depth, etc.)
Once mining operations have begun, an inspector should make certain that the augering is
conducted in the locations and in the manner indicated in the approved permit. Verification that
the auger holes have been properly sealed is a difficult procedure and is discussed in detail in
Section 1.2, Control of Infiltrating Ground Water. If verification that the auger holes are below
the water table and flooded after reclamation is deemed important, monitoring wells can be
installed in and adjacent to the holes to monitor the ground-water conditions.
Verification that coal is not being stockpiled is accomplished by a simple visual inspection.
However, where stockpiles are allowed under limited circumstances, slightly more effort is
required. Verification will be needed to ensure that a liner was installed, the pile is usually
covered, or that there is a limited onsite holding time.
Operational BMPs
3-25
-------
Ill
Ill ill 111 111 III III ill 111 III II
III 111 II illllillllilllllllllllllilii illllPllillllllillllllllllV
II I ill 11 111 ll III
11 ii ii in iiiiili ii iiiiiii i nil
Coal Rdmining BMP Guidance Manual
IlilJIR^ ii! BliiliiaJiiiliiiiili' :''lli!:ji;'l!i:^')i!::, i ...... i . ',' \ ..... n ซ ' : ...... ; 1 i ^,t ]"'\vvui w
' ,, .,ซ i .JNTIEI" < / n ; < < "i
i! :' "i ii auu a>L ii'inn ir iiiinii
s ...... determination ..... can be performed onsite during construction or after installation, but before
*'';'I''*';''li1'' !!> ' * : "!ii*l'*'**'L:''tl'ri*'1 ...... ;ill':i'li|i:i ..... '''1'" ...... ' ..... ' ....... 'lir*i!'*'1* ...... ซ*ป;i';i'^*jir*i ..... -"
B ..... I
ปl:i;i ....... \litisel1 "An inspector can also verify that the runoff is collected and routed to a treatment facility. If
thej-efsa, discharge visible at the base of the pile, but it is not reaching the treatment facility, this
is an indication that the leachate may be infiltrating into the ground and will eventually reach the
iHSp;lr*.,''Ssrafer1Sabl(e. If no drainage is observed from the stockpile during or immediately following a wet
..... ....... *- ..... 'ซ ..... 1'*1'^^ ...... 1'11'111''' .......
*
I the situation. Elimination of coal storage or reconstruction of the liner may be required.
I !! iff _ _ I
I lii'Verification of the application of a bactericide can be performed by reviewing sales receipts or
'M^lBieing present when the material is applied and reapplied. Stockpile covering is accomplished by I
inspection. The lack of any runoff from the pile is an indication that the cover is being
I III 1 1 iilllill : li.!';i ..... 111'1:!' '"iiillHlllii Ui ....... IliiiMH^^ .ill'. * ill ...... iil V i ...... 'iNBIil.Iit' ' tiili ..... 1M! ..... ill1!) ซ#i'>HซM ..... '*I!i!!l ..... !( .......... (('.> ifmiMifl, '.NISI! WHiWP *W#iWI0l ซ ifmiMifl, '.NISI! WHiWP *
. i-a-tiirii1 .> ;' unit '".i: ....... , ....... iii,i:,iiwiiir v. " M JHM^^^^ ..... <
lr;i :nillK 'llllllii:' -l
' < '
g me ...... amount of coal ..... removed from the pit to the ...... amount shipped
amount taken from the pit is a simple calculation:
!i ............ ' ...... ' ' ....... ' ..... 'li;':' ..... " " ........ Si .............. ....... ' :i ' .................. ! "! ......... ! "" '"'' ....... "; ........ ...... ' ;! ;" ..... ...... " ........ ;: ..... ' ' !!!; '; " ! '" ' L * .......... '! : ' " * ! ! ! ' ..... ; - !; i! '" ' ....... ................ ' ..... ' ' " ' " .......... ' : ........ ' ..... " ' '! ..... * ..... |l!:: " f ' '" !; ' lp: : ....... ' " " '"' ....... "' '' ' :" '" "
*= ; , ;;;;;, " :;;,;, ;,; ;; '; ; ~ ;;;; " ; ;;; ; :;;;;;;,;;; .; "I;,;, ""' ; ," ....... ;;: .;; ; , ' ,; ..... ';~ ; ; . , ..... ;; .;, : \ ,;, ~;i :;;';;;;, ,;;;;; ......... ; , ..... ;;;;;;;;;, ; :;;::;: ;, ;;;,; ..... l;,; ,;;; ; , ;;; .;. , . ( , , ;;; ..... ; ; , , ;
;\;:: :,::,; ..... ,!::5I;::,Coal ..... Thickness x Acreage x 1750 tons per acre/foot of Thickness = Coal Tonnage
,ซ,Liป:i MTปซM ..... '< 'ซซซ
erificjal;ion of the ampunt truclked off-site is available from dated weigh slips or sales receipts.
he, inspector can also observe the removal of coal from the stockpile while no coal is being
^i'lij^illi'''':!.!:!!;1 ,1! iiif 1 illiJT1: IfetMlBBMH 'liii!!. iSif!" *t- ..... ! ..... ' : ' 1' if!1!1 f ^ >ll|i:* 'i1'*"- I'll1!'11' "! * i :i1!l||i!':i> :* -" ..... <"ซ "*K:ff!f f-ซ :"j! ' , "" lijl''!'! ''] : 'i i'i-i ........ '( iit
' [[[ 1"" ' ' ' '
i ...... w ! jjli ' i ii;i I :: , s i ' ปii fliii*, '' ' 11 , 1" ' i iiii ...... ;1 : ' ! I/ : " 1
I"-1'!;!,' ...... ii'iiiii1!::1*) ...... j'liit"' ..... :i ...... icji'i'Mir ...... ^'i:,!,)" 'iil ..... IH. :>
iThe delineation of acid-forming materials is verified by review of the overburden analysis
submitted with the permit application and discussed in Section 2.0. However, it is recommended
that the inspector periodically examine the exposed highwall to ensure the lithology expressed by
the overburden drill hole logs does not appreciably change across the site. Channel samples (a
.' JEvertical ...... serjes of overburden samples collected by hand, comprising the entire exposed strata)
I;1 y, i :
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....... i ..... IIUIH^^^^^^^^^^ ............. liliiilM^^^^^ ......... iiilllB* iii
nil ..... i
-------
Coal Remining BMP Guidance Manual
may need to be collected at the highwall and analyzed to verify that the overburden quality has
not changed laterally from the nearest overburden hole.
Visual inspection will permit the determination that the amount of reprocessing, or refuse
removal, taking place matches the original plan. The amount of CCW returned to the site can be
determined from weigh slips and volumetric calculations. The quality of the CCW and potential
to leach toxic trace metals can be determined from laboratory analysis. Adequate post-mining
slopes and vegetation can be measured in the field and compared to those proposed in the permit.
To ensure that the maximum amount of daylighting is completed, certification from an engineer
or registered surveyor may be needed. The inspector can visually estimate the daylighted acreage
to a reasonable degree of accuracy. The operator may need to flag the site to define the limits of
the daylighting on the surface.
Implementation Checklist
Monitoring and inspection of BMPs in order to verify appropriate conditions and implementation
should be a requirement of any remining operation. Though BMP effectiveness is highly site-
specific, it is recommended that implementation inspections of Operational BMPs include the
following:
Measurement of flow and sampling for contaminant concentrations before, during, and
after mining.
Monitoring should continue well beyond initial water table re-establishment period (e.g.,
about 2 years after backfilling).
Assessment of hydrologically-connected units and/or individual discharges.
Review of liner material weigh slips or receipts and/or inspection of marked stockpiles.
Assessment of any deviation from an approved implementation plan.
Inspection of salient phases of the BMP implementation.
Frequent inspection to determine reclamation concurrency.
Operational BMPs 3-27
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!fง'.fiir^i^,'^^ Coat Remining BMP Guidance Manual
.t observation of the handling of pit and tipple cleanings and stockpiled coal.
":i '"t:'i'! '"'I1'1 'Hi Jij '" :"SZ ' 'S"'SS^SKaSX, * "''''. T! 'i' * i:il1''" 'SSS* ซ, ;>ซ j!1 ,i" ' ,,:;;; ***f^ ฃJ? J'JSJ !
iiasfaisiH: 'is- SB?' i"ซ*f-"i^si Inspection of augering operation or lack thereof.
: -ij^i^^
'Jปi^f '.'.OiPiaaTii'liw;! 'iifiiii'ili ll'si' tw .'ifawwmi ,i>'r rMll E m'M'
ซซ'ili',="',ReYjtea? of coal recovery or refuse shipping records.
' ~- ;; ;!-- Monitoring scope of daylighting.
3.3 Literature Review / Case Studies
'''I'lJUIii/i, I'M!",! Ill'" ! I1
.^..o?'??? ??7) iscussed" the impacts of operational cessations on post-mining discharge
i NiyFgHlkttllR! f rl '!*iji'i,;di^^^^^^
;i =SM%aualit^_for several surface mines in Pennsylyania ^d West Virginia. Their conclusions
were that rapid mining without delays generally yielded improved post-mining water quality
to similar mines that experienced delays or cessations during mining. One site in
kpailicular (tEe Greene Mine) had two discrete mining phases. Mining and reclamation on Phase 1
! , :i,!,f^ iซ^^^^^^^^^^^^^^^^^^ iia^^^^^^^^^^^^
proceeded without delays, while the mining on Phase 2 was interrupted by a two and a half year
cessation of operations. The two phases were also hydrologically separate. Phase 1 was mined
*~WitJipManฃwork stoppage. While Phase 2 was idle reclamation was incomplete and the acid-
5 forming overburden material was exposed to atmospheric oxidation. The post-mining water
, Illllllillllll'i IJfti ,, lillii,,: Jin, 'HI, Jinilliifi'lil'llllliilllii i ,i,i'"'lซi: llilillii'i, ! iinilllB'ln ; il If1 h!!"1 ',:! Ill IIIIIRHIIII!!!' ?! AiliUHI'li 4! "lilifllJli ' ,,,,1'ii' :! Ill, 1 iiil'1' 'I ft!1 Jlnliiliii! 'i i';.,i, ''ft1' i'ft InlPi. Hi! li! >,!;: IIVI1.. H!!"!'1 " il1' \N' 'DlilJIill" Ki' ,ll""l. , LIlKllllllllii.!'. i i'iLii'l'JIIIftft ,1111 i"B n iii, i ': in.' I,: "'illi'".!!1!1:!: Ill < 1! '|i illlnililllli,!'',,"! liHIIHKJII.il, ,,i (uftujftillftilli (,i,!n >!: n"! ., ' I1'1 i 1!' ' , 'ilili n...' i 'in' ft,' Ulftlllllllllllll "I'
ฃฃgfiฃfiy o^g^e J.^Q pjjgggg was distinctly different. The net alkalinity for Phase I was 151 mg/L,
I
II~ "I:::;';,,,:;;'':::, While..that of Phase,2 was -12,8 mg/L (net acidic). Iron concentration for Phase 1 was 1.88 mg/L,
iiliniliiM ill::1!!"'"!!"!:!, I'j'!,:1!!!!1!! 'i1!:!::':,,!'.!' |
while Phase 2 yielded 18.7 mg^L. Manganese concentration for Phase 1 was 16.4 mg/L, while
='^";'";;; ;;';" ;^the concentrationjor Phase,2 was 62.7a,mg/L (Perry and others, 1997). Sulfate concentration,
'while not a regulated effluent parameter, it is a viable and direct indicator of acid mine drainage
s5on. the sulfate ion is released as part of the mine drainage reactions and except under
5 1RHBTO, W^9jte913S* The .^^MH^fejiJ..!^^ phases of the
filrtMHM iili &f!i :^,:tilpftlllE;iiBtllซl;i{.ifHKGil( Ill* s i " '. , *
a difference in the volume and rate of mine
.ge pjroauctipn.ii Phase _1 ...... had| a sulfate concentration of ...... 1197 ...... mg/L, while that of Phase 2
was 1770 mg/L or an increase of 48 percent. The lack of acid production at several other sites
, j'
jn the study was attributed to the rapid mining followed by concurrent reclamation of
andothers
iUi "l.Tiiiiii1 ftซ "I ? i Jliill'I ll/'i'irlir < I I
: liiiiiiiiiiniiii"'t'111, ir'ir'" iiSii' iiJIiiii1 'iiliijiiiili'<'i!i!iii JiiiHiir i'"1 iiii1':'iiiiii"'li'1 lil!Jiiiiiiiif:>'. < >^fi"s'/I|I7:Si!iiif !*i' ii"" i '!i*iilii m inniJ:HIiiiiiiF'i'iftiiiiii'iiiiiiiiiii1': SSI :'i:'i,Hiiniiiiii I
, |f f]t, Operational BMPs
'I''!'1' I'.'Ni. rii"' ;i:;;]'i:-i. "i'iiili iifi'':1' 1 '' '"i (! JJ^j'tiUlrt! l^ijiw.il
ilhi Iji'iinillll ; i, in ilw, 1 ' :,! \K\\ 'i \S '" ;,ii ill! ,pi 1 1 ; 1|!" n1 ;!! ..... \ Wi It: liilniliiiihii, 'iBfiWilCf Jill,!!!"1 1* I:, I ilii'Blli1 < i1 1,1 ' IliimiilHi'li!'1: ' < < iliillli' <: iHKIilKi'l'i II1 , 1!! i1 '! i1!1' il '''HI ,i!ii': riJ n i '' / ; JIlliiilBllh'iin I'l f " << I',, '#
, iii'inijilll!1 , ill'liHEIIHili lill'KslL ..... , all '<
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Coal Remining BMP Guidance Manual
3.4 Discussion
The operational BMPs discussed in this section are recommended during remining for
controlling the effects of the mining activities. Rapid and concurrent reclamation, appropriate
location of auger mining (if allowed at all), off-site disposal of acid-forming materials, control of
coal stockpiling, and thorough daylighting are operational procedures that should be
implemented as part of the mining plan. Coal refuse reprocessing is a type of remining that
should be encouraged. These BMPs do not preclude application of other BMPs discussed in this
guidance document or required for environmental maintenance or improvement.
Benefits
Rapid/concurrent reclamation reduces the risk of the operator falling behind which often
results in incomplete reclamation and promotes AMD formation.
Off-site disposal of pit and tipple cleanings may transform a remining site from producing
additional acidity to producing less acidity.
Appropriate implementation of auger mining can maximize the amount of coal recovered
while reducing the risk of increased AMD production.
Short-term or no coal stockpiling reduces the risk of accentuating AMD production.
Reviewing the overburden quality and making a decision on permit issuance or denial
based on this review will lessen the likelihood of making the pollution loads worse and
the operator assuming treatment liability.
Removal of significant amounts of acid-forming materials from refuse piles and
introduction of alkaline material decreases acid and metal loads.
Daylighting radically changes the geochemistry and hydrology of the site, reducing the
amount of acidic material, increasing the potential for ground water to encounter alkaline
material, and reducing the water infiltration volume.
Operational BMPs
3-29
-------
I
11 in inn iiiiiiiiii
iiiiiiiiii iiiiiin
III I II IIIIIIIIII I I 111
III 111 I
I I III II 111 I 'III
Coal Remitting BMP Guidance Manual
111 iป
in iiiiiiiiii iiiiiiiiiiiiilliiii iiiiiiiiii
iiiiiiiiiiiii
iilllllllllf iliii'llllll'V1-11 "I1 '*!
Ill !il i Limitations
Unscheduled or unforeseen circumstances may prevent maintenance of concurrent
reclamation.
Off-site disposal of pit and tipple cleanings may not be economically feasible.
Without the approval to auger mine, some abandoned mines may not be economically
viable to remine, because of the limited coal recovery.
Auger mining above drainage areas may not be permissible.
* The coal market may dictate whether or not the coal may need to be stockpiled.
Avoidance of stockpiling may induce coal sales at below anticipated prices, possibly
compromising the economics of the operation.
Jl'iSBSSif ";'.,!,;
t;lIiiB :;'Tl
p,:' iiiiii ijppp i| jซ:ป!ป iiiiii; iii<'iFi"i'i,]|,ii i ' p, , 'iiE , j'ii i',p| 11'jiij, p t' |, ' hpn,,' ip,, , p mi:, < i
,, rSPIIP'P'Lliiliil 'iluPIIIIPiillii'JIiillllllllili'F i!liii,!,!'M,!<:. 'IP'iiiil,,, IIIIII III1 'P" i, I'IIP iilP'iiillllllii, Pi III!, ' ftiiij,, llllliH.n i, 'IIP I'Pil1' ,. ,w$i-i\, iiiiii; n Mmsmf^mm^.
ซv^i m% mat: siifivit is x sEiiii ,. ":;;;; > ;;: j ' mmmwmmiiM
. ^Analysis of sites with Coal Refuse Removal or off-site disposal of pit and tipple cleanings
showed that two thirds of the discharges were eliminated or significantly improved in terms of
|q|dity loading (Appendix B, PA Remining Site Study). The remaining one third were
unchanged. Almost 86 percent of the discharges exhibited either no change or a significant
triii, M^^^^ I
111!: t'vi
'';fJ7^sSigJftificantly worse. No discharge was degraded in terms of aluminum load. All were unchanged
',,,11,"" !11i!lK liiWII Mil IBCT^
>'Hl i!" J fSf
1!,11:1,1!11!,!!!;!11:,! ...... M::'!.;ii i ........ i ..... IF1;1, ',,,. I, ".i, ';!!'!.,
i :"Tซ3.1: lil'I'liillli: -,'.:i!|!i Hmsa
'".'id,, ' IIJ'M1." IFi1':'!"!"!", >' i1"! ' '"i1 *!"li; >
: - - .
^^^^ :L
>j lllllifi'l IJIIIU;,; iiiiiiiiii;; J;i
li'S Jli'iii'll'-'ViiillFiilirii!)1''- ,:tl '*;i:IH Jil'i ;,i,
Illiifi !"l ..... ..... t
'^" ซ"', h,!i "i /ill ..... iK, .!,!!
Jilt I
''j^he.success.pfMining of Highly Alkaline Strata is directly related to the overburden quality. At
!,! llllllI'lL It ,ฅ'.< ',,'Fi; 1" ' '.I'M, ',v ,IF i!> ' "' , ' ' , ,lซ i',!, - 1!, ,:>,, ' ' , , "I:, I J J , |
''i~|ites wherg alkaline overburden existed,,,no discharges were made worse by remining, while over
OperationalBMPs
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Coal Remining BMP Guidance Manual
three percent of the discharges exhibited significantly higher iron loads. Another 39 percent were
unchanged and the remaining 38 percent were significantly better or eliminated. None of the
discharges exhibited degradation in terms of manganese or aluminum loads.
Less than one percent of the 170 discharges analyzed for Daylighting showed degradation due to
acidity loading. Over 58 percent were unchanged, with the rest being eliminated or significantly
better. Iron, manganese, and aluminum loads exhibited similar results with a slightly higher
degradation rate (about 4 to 6.5 percent).
3.5 Summary
In general, operational BMPs are "rules-of-thumb" for good mining procedures. Research and
experience has demonstrated that these BMPs will minimize the potential for additional AMD
production; and thus, increase the likelihood of reduced pollution loads.
These recommendations are intended to prevent unchecked, large-scale pyrite oxidation within
the spoil and adjacent areas. Once accelerated oxidation has occurred, abatement or treatment of
the acidic drainage becomes increasingly difficult, if not impossible. In general:
Rapid, concurrent reclamation is a good practice regardless of the overburden quality.
Off-site disposal of pit and tipple cleanings reduces the probability of additional AMD
production.
Auger mining should only be permitted below drainage or where effective auger hole
sealing will preclude AMD production.
Unless the drainage is controlled, extended onsite coal stockpiling is discouraged.
Overburden quality should be a consideration during permitting remining operations.
There are very few, if any, problems associated with coal refuse pile utilization.
The greater amount of daylighting during remining will produce the most positive
reduction in pollution loads.
Operational BMPs
3-31
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Coal Remitting BMP Guidance Manual
References
'' I - Brady, K.B:C. and R. J. Hornburger, 1990, ^The^Prediction of Mine Drainage Quality in
W Pennsylvania, ^yater Pollution Control Association of Pennsylvania Magazine, pp.8-15.
' 11: i llllili i.- Pi ffifcuT, mmiif am rtmtww . if; : it IP ซปt ป;": w"!1 'ฅ: i!f ซ::i MM!: w /^M,/ ซ tij iti i *? :\U\ Vi AMilll
on1 P;M.fl R.L.P.|Keinmann,|(and S J.jOnysko, 1985. Control of Acid Mine Drainage by
^ ^,.!^_^ p"roceedlngs of"
Technology Transfer Seminar, U.S. Bureau of Mines Information Circular 9027, pp. 25-34.
Hawkins, J.W., 1998. Hydraulic Properties of Surface Mine Spoils of the Northern Appalachian
Plateau, in Proceedings of 25th Anniversary and 15th Annual Meeting of the American Society for
Surface Mining and Reclamation, St. Louis, MO, pp. 32-40.
! Hem, J.D., 1989. Study and Interpretation of Chemical Characteristics of Natural Water, Third
Edition, U.S. Geological Survey, Water-Supply Paper 22547263 p".
"IB I1", i.il1, iป ' / III
Jennings, J.N., 1971. Karst. The M.I.T. Press, Cambridge, MA, 252 p.
IS ::-;: ii*l to 6-9.
:Ww
'ii I;.;. iLusardi
lilWIIIIIIilllir.illlill'Ti'llli1:,!,;
LllEil!
LJI iLiT IP ni
and P-M. Erickson, 1985. Assessment and Reclamation of an Abandoned Acid-
ii ''''I'iliiiiiiiiiiiiiiiiiii i iiiHiiiciiiiiii:iiii ' ''iiiRn ii ii iiiiii; iiiiT'K aiiN, niiiiGi aii ,,*' ii,, niiKi;}'' tin n11 iiiinuiK' in 111.11;" f iiiinaiii P< i11' ^''i inj M, " ..inuui ^ ''i&iiEi1'', i ii.iit iiiE'iiiii'iiiiiirniiiiiiinnii iiii^iiiM', ,i i tut lie" < i^iiiiiiiiiiiiiiiun g< nirii iff n\af>;f\ a, 'iiiiiiiuiRnii; s:" >,: i;:,'!' in 'Piiiniii:; iiiw
_ Strip Mine in Northern Clarion County, Pennsylvania, in Proceedings of the 1985
Symposium on Surface Mining, Hydrology, Sedimentology, and Reclamation, Lexington, KY,
pp. 313-321.
Pennsylvania Department of Environmental Protection, 1998. Coal Mine Drainage Prediction
and Pollution Prevention in Pennsylvania, K.B.C. Brady, M.W. Smith, and J. Schueck, Technical
Editors, Harrisburg, PA.
I i iiiiii mi i i i n i i i i i i i i n i i n in 11 i i|in i i
Perry, E.F., 1998. Interpretation of Acid-Base Accounting, Chapter 11 of Coal Mine Drainage
Prediction and Pollution Prevention in Pennsylvania, PA DEP, Harrisburg, pp. 11-1 to 11-18.
Ill i III Illlllllllllllllllll lllll I I II I 111 II I I II I II I 1 I 111 II i I I 111 Ilil I hill II II ik';,,:,i";;:ซ"''J!'if ''t!irt'i'l
Perry, E.F., M.D. Gardner, and R.S. Evans, 1997. Effects of Acid MateriaJ Handling and
Disposal on Coal Mine Drainage Quality, Proceedings of Fourth Mernatipnd Conference on
Acid Rock Drainage, Vancouver, B.'C'Canada, VoL'in", pp! 1007-1025'!
3-32
Operational BMPs
Iiiiili" If! M* , ^IFF Hi Illiliiln I 'I'liilHS1.
.
' ''lilSI'S ..... ill ..... , >' .il""1','"^ '':' i IhRi1 II, I'1'11!1!111 '!, .,,*!'" It ป ,' ..... ' ' 'i<'iiil 'M1'!!"'
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Coal Remining BMP Guidance Manual
Reed, L.A., 1980. Effects of Strip Mining the Abandoned Deep Anna S Mine on the Hydrology
of Babb Creek, Tioga County, Pennsylvania, U.S. Geological Survey, Water Resources
Investigations 80-53, 41 p.
Rose, A.W. and C.A. Cravotta, 1998. Geochemistry of Coal Mine Drainage, Chapter 1 of Coal
Mine Drainage Prediction and Pollution Prevention in Pennsylvania, PA DEP, Harrisburg, pp. 1-
1 to 1-22.
Smith, M.W. and K.B.C. Brady, 1998. Alkaline Addition, Chapter 13 of Coal Mine Drainage
Prediction and Pollution Prevention in Pennsylvania, PA DEP, Harrisburg, pp. 13-1 to 13-13.
Sobek, A.A., D.A. Benedetti, An V. Rastogi, 1990. Successful Reclamation Using Controlled
Release Bactericides: Two Case Studies, In the Proceedings of the 1990 Mining and Reclamation
Conference and Exhibition, Vol. 1, Charleston, WV, pp. 33-41.
Stumm, W. and JJ. Morgan, 1996. AQUATIC CHEMISTRY Chemical Equilibria and Rates in
Natural Waters, John Wiley & Sons, Inc. 1022 p.
Watzlaf, G.R., 1992. Pyrite Oxidation in Saturated and Unsaturated Coal Waste, In the
Proceedings of the 1992 National Meeting of the American Society for Surface Mining and
Reclamation, Duluth, MN, pp. 191-205.
Watzlaf, G.R. and R. W. Hammack, 1989. The Effect of Oxygen, Iron-Oxidizing Bacteria, and
Leaching Frequency on Pyrite Oxidation. In the Proceedings of the Ninth Annual West Virginia
Surface Mine Drainage Task Force Symposium, Morgantown, WV.
Operational BMPs
3-33
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Coal Remining BMP Guidance Manual
Section 4.0 Passive Treatment Technologies
Introduction
Passive treatment encompasses a series of engineered treatment facilities that require very little
to no maintenance once constructed and operational. Passive water treatment generally involves
natural physical, biochemical, and geochemical actions and reactions, such as calcium carbonate
dissolution, sulfate/iron reduction, bicarbonate alkalinity generation, metals oxidation and
hydrolysis, and metals precipitation. The systems are commonly powered by existing water
pressure created by differences in elevation between the discharge point and the treatment
facilities.
Passive treatment does not meet the standard definition of a Best Management Practice (BMP).
In general, BMPs consist of abatement, remediation, and/or prevention techniques that are
conducted within the mining area (at the source) during active remining operations. Passive
treatment, by its nature, is an end-of-the-pipe solution to acid mine drainage (AMD); it is
treatment. These systems are frequently installed after reclamation to treat AMD. BMPs, on the
other hand, are performed as part of the mining or reclamation process, generally not after the
fact. If treatment, passive or conventional, is required for a discharge to meet effluent standards
(BAT or some alternate standard), the operator is held liable and treatment continues,
theoretically, until the discharges naturally meet the applicable effluent standards.
Regardless of whether or not passive treatment fits the definition of a BMP, it can be used as part
of the overall abatement plan to reduce pollution loads discharging from remining sites. There
are situations where passive treatment may be employed to improve water quality above what
was accomplished by the BMPs. Therefore, a detailed discussion of the use of passive treatment
Passive Treatment
4-1
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Coal R&mining BMP Guidance Manual
technology to treat AMD in this manual is warranted. Passive treatment includes, but is not
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Constructed wetlands
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Pyrolusiteฎ systems
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Passive treatment technologies also can be incorporated into the reclamation plan along with
more traditional BMPs. For example, ALDs can be installed within the backfill as a type of pit
:::floor drain. This hasbeen done aX,a jejnjning site on the Shaw Mines Complex in Somerset
County, Pennsylvania, where an ALD 2,500 feet long, 30 feet wide, and 10 feet. deeg was
installed within the backfill (Ziemkiewicz and Brant, 1997). Wetlands can be constructed where
: lllllll!i|i||iliillllllll|i|lll||||||||i "'i r",U' ,4 Hi,!,Jill,, P! lllliillil'iilllllllllllllljlllllllll'llli'i T "lirailli*1!!! mill! .H.JIIiiimil IIIPPIP''!^'!!:!')!!!^!'!'!:!!!!!'^!!!!!!!!!!^!!!!!)!!!!!!!!!!!!!!!!!'''!!!!!!!!''!!'''!!!''!!'^!)!!!! Iliilllllllllinillllkillli'PfiiU iWliMI'lllii !!!,:, lii'illlNiii'pMK ' ,,,ll : i'1!!*' , imil'lilll'TilBlllifl
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the site completely to the approximate original contour is not economical. Discharges
ป'Lilt lll|l|iiii||iiiw ii 'i|lllllll||lllliii'"'' tllij"'1" fii'ii V'liiiiiiiiiii'ii'iiin^^^ iliiipi'liny" 'iiii'iiiiniiiiiinnii "i it ijiuirihi'iriHl! ' f*m , ,:,. , ' ' ' , p 'i., "","i ' " i',' , , ' q , , O
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Once installed, passive treatment systems require little maintenance through the projected life of
the system. They are a low-cost method of treating mine water. However, these systems have a
finite life and may require rebuilding or rejuvenation over the life of treatment. The period of
treatment can be considerable; some mines have continually yielded AMD for well over a
century. The power to run these systems is generated by changes in elevation that creates
|
4-2
Passive Treatment
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Coal Remining BMP Guidance Manual
sufficient head and forces the water flow through them. The treatment is performed by natural,
biological, geochemical, and physical actions.
Frequently, more than one type of passive treatment or an integrated system of passive treatment
technologies are employed to treat mine drainage. These facilities, like conventional treatment
facilities, are typically designed to raise the pH and remove metals (e.g., iron, manganese, and
aluminum) of acid mine drainage.
Site Assessment
In order to determine the feasibility of integrating passive treatment into a remining BMP plan,
there are several factors that need to be assessed. The most critical is the determination of the
water quality and discharge rates. These data need to be collected and analyzed on a seasonal
basis to completely characterize discharge(s). Sampling at least once per month, for a complete
year, is recommended. Additional monitoring may be required, if the precipitation has been
substantially above or below normal. These data directly relate to the sizing of passive systems.
Of particular importance in selecting the type of passive treatment system(s) is the water quality
characteristics of the discharge. Dissolved oxygen (DO) concentration, speciation of the
dissolved iron (i.e. ferrous and ferric) concentrations, dissolved aluminum concentration, net
acidity or alkalinity, and pH are all important parameters. The concentrations of dissolved
manganese and sulfate are of lesser importance (less problematic), but should also be determined.
Determination of the discharge flow rate is perhaps the most critical data for the sizing and
selection of passive treatment technologies. Without accurate flow data, an improperly sized
passive treatment system may either under treat the water or be much larger, and thus more
expensive, than needed. Flow measurements should be determined at the time water samples are
collected and should be performed using standard scientifically accepted means. A weir (e.g., v-
notch) or flume (e.g., H-type), timed-volumetric (e.g., bucket and stopwatch), or flow meter and
Passive Treatment
4-3
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cross sectional area are acceptable and commonly used methods to determine flow. It is
I
ijecomn^ende^^atat least one extreme high flow and low flow be sampled during the
monitoring period. If the flow is too low or too erratic, some types of passive treatment (e.g.,
wetlands, SAPS) may not be suitable.
Most passive treatment systems require a sufficient gradient to create the desired head to drive
the water flow through the treatment systems. Therefore, implementation of these systems
requires a large enough area for construction sufficiently down gradient of the discharge.
1 " I
4.1 Implementation Guidelines
i ii'iiiiiiiiiiiiiii ii n i
^Anoxic Limestone Drains
In general, attempts to use limestone to treat acidic ferruginous mine drainage at the ground
a^ter a ??!01l,timl,,E5Eio^: ...... JJ^se, failures ...... are caused, by the low dissolution
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rate of limestone at atmospheric levels of CO2 and by iron (ferric) hydroxide (FeOH3) armoring
.ii;;:ESCfesiij?ie(Stone. Limestone armoring virtually halts all bicarbonate alkalinity production from
; ..... !illi;1!S? ..... iissptotion of calcium carbonate. Once exposed to the atmosphere, the iron rapidly oxidizes
from ferrous (Fe2*) to ferric(Fe3+). Once oxidized, ferric iron will quickly precipitate out of
,5 ....... ,'BงliltiQDป coating the limestone, and creating an iron hydroxide precipitate sludge known as
i1 ..... IIMH^^^ , 'iiiaiiiR'itiK ...... raiiB; in, ........ . ' k 11 ...... iiiii riv^^^^^^^^ * iKiH^ irr iiiiiMSiii ia!tปii&!< w ..... vim t mi iiiii i HI i
boy". However, if mine drainage is maintained in a low oxygen (anoxic) environment,
"*' i::,!, BIH^^ IB:* JiiiBi1 ..... II
if'StKe ...... iron will remain in ..... the ferrous ..... state and will not readily precipitate from solution. Anoxic
=rmme_water passing through limestone drains allows for the production of alkalinity without iron
araioring and precipitation. For these drains to function properly, the mine drainage dissolved
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xygen ; content should be less than 1 mg/L (Kepler and McCleary, 1994). Cravotta (1998) states
>fmm 'ism ; ". m > mmma: ..... itf1!: ii! i; 01 ^ m i, 'i^ m-xmm ..... "B ....... jiiif'!1' 111^^^^^^^ ::ซ ..... in mi ..... ":- ........... iiiiiiii IIIIIHUII 1 1 i ii n 1 1 i i iiiiiiB n iiiii
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dissolved oxygen in the water should be less than 0.3 mg/L to preclude iron oxidation.
............... ' ............................................ ........................................ [[[ ...... " .................................. ..................... ...... .......................................... ........... 1
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designed to generate alkalinity in acid mine drainage without
||Eeric exposure. In addition to preventing iron hydroxide precipitation, the closed
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Coal Remining BMP Guidance Manual
alkalinity production. Alkalinity production in ALDs is much greater than what can be expected
at atmospheric CO, levels. CO, partial pressures ranging from 0.022 to 0.268 atmospheres were
calculated for 21 ALDs (Hedin and Watzlaf, 1994). The production of 61 mg/L alkalinity under
atmospheric conditions can quickly be increased to over 450 mg/L within an ALD (Hem, 1989;
Hedin and Watzlaf, 1994). The mechanism for increased alkalinity production from higher CO,
concentrations is discussed in Sections 2.0 and 3.0. Removal of acidity from mine water flowing
through ALDs ranges from 0 to over 5900 mg/L. Higher levels of acidity removal are attributed
to loss of mineral acidity from detention of ferric iron and aluminum within the drains. This
detention of ferrous iron was observed at two sites using ALDs with detention times exceeding
25 hours (Hedin and Watzlaf, 1994). Lower acidity and higher alkalinity of the water once it
leaves the drain cause water pH to rise, which in turn significantly increases precipitation.
ALDs are often installed to aid the efficiency of constructed wetlands. These wetlands work
more effectively to remove metals if the pH of the water is raised by ALD pretreatment. Most
metals associated with AMD precipitate more readily from solution in a high pH environment.
Nairn and others (1991) stated that a pH of 6.0 (standard units) and a net alkalinity allow passive
treatment systems (constructed wetlands and settling ponds) to work much more effectively.
Design and construction of an ALD should be based on the required detention time for the
maximum flow anticipated for the discharge over the effective life of the facility. The discharge
water quality should also be considered. It is recommended that an environmental safety factor
be employed in design to cover the worst case scenario. The discharges should be monitored for
at least one year prior to system installation to determine the range of flows anticipated and the
variability of water quality. Precipitation records during the monitoring period should be
compared to average years to determine the representativeness of the flow and water quality data.
Configuration and size of ALDs are based on the flow rate, projected life of the system, purity of
the limestone, and desired water quality. The ALD should be able to treat the water to the
desired levels under all flow conditions. Design details of ALDs can vary, but the general
configuration is relatively consistent. Figure 4. la illustrates the basic construction of an ALD.
Passive Treatment
4-5
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3II",1.,!! i' ' ?'!B Jillili'i I 'WJR" JOIl^uJI I
<: iiii'fi'f1"" ::ii"i .mi :,ii' I'fiiirr liiiiiiiiiiiiiiiiiiiiii: fiiiiiiiiiiiiiiiiii i''.
liifi\ :";'i,Bi' i,ij'i "!i!?"; 91 j'"'.Mr'i: c; ^.,iiiiinii n:me"^r:ffji^1 r.ซ:*.1 tirffi; wri :!' -11!"'; &ฃ^UHItn; j- r >,^,..." ; ซง ',,,'.? u ,"!^;i^^'.Ji,,,Bjt' /x-;ซ"i:i;i! iii^ifiMi'1 * .ii imwt^r;i.^# '[fftji^ n yiH'. iiii'vi1 ;^i
III!; i III Ifllf" " Iff! i ,. ;. llllff I,!ป' "III, vi1" Liii'iliWiiil'tiiiii!' fiiinfllllillfllf, i, IV Hill,, P. "Uf ffl fllll In ,f lllfllf, lift ,f T" ,;, n'f" ,,i :ซ i' ,,:,;!,; i', If'Hi fli",, T! ปT '? " f ifiiiff :'ii,if i'ii''"'if i' ,f, "If Hi If ' i, if! fiflffil1 .IIP I i,!ff" ffn if f Ifi','if",, ., i.ri if If III ""'Ii"!1",,' f^Jii'/iHllIIIIII1: Illllillll'.1 t" 'iff I
t^ and flow data Jram ..... 21 completed ALDs
^"' ......... *I;'!;.:1^ ::iil1 ' , ^treating ...... AMD ....... In AppaTachia to ..... determme'Aeir'eMciency" ..... T^e'y detennined that an in-drain
IIIIIJ ..... If ' i Will i11 i'l, 'III!1 IB, TfjihlijlMffi PI fif 'If Hi ..... ifiw ......... |,|;i iiiiiiiii llllllilil|n|,fi|||ii,i vi,,,^,:'", ................. ' ............... ,:,!ป, .............. .............................. ..... n ', .......... < p:~ ......... r ...... ,iซ>! ''iiiii:
fllfffl ' I fuJllffi "' ,i,"ii f!' fllffjii:,,
'i;,!]"!":' ........ ,>:,!, ..... Euiii',: iviyiii'i .liiiiiiiii, ,ป, U':,',
^^^ Li, '!, l,!<'|, slij"!:)!: JIIH^
f'i,;!'"!1!,,;,:! ' , -inifiilllfll,!,! i '. icfffll i flfi f'fl'fi.N/ LUoUIidX^C ld,LC
pb = bulk density of the limestone
td = the detention time
Vv = bulk void volume expressed as a decimal (20 percent voids is
expressed as 0.20)
C = predicted concentration of alkalinity of drain effluent
T = designed life of drains in years
x = calcium carbonate content of the limestone in decimal form
iiiiii 1111 in 11 in
Passive Treatment
in (i ( III i li11 111 i 111
iiiiii i iiiiii iiiii
IIIIIII IIIIII III
in i iiiii iii iiiiiiiiiiiiiii ii iiiiiiiiii i iii in i ii iii 11 in i 111 iiiiii i i i i in
IIIIIIIIIIIIIIIII IIIIIH^^^ 111 IIIII III IIIIIIIIIIIIIII 111 IIIIIIIIIIIIIIIII IIIIIIIIIIIIIII I 111 II II IIIIIIIII I II IIIIIIIIIIIIIIIII
II IIIIII 111 I I III I III 111 II I 111 III I II 111 II IIIII I 111 111 IIIIII I II 111 111 III II IIIIIIIIII I IIIIIIIIII IIIII
iiiiiiiiiiiiiii 11111 ill iiiiiiiiii 111 iiiiiiiiiiiiiiiii iiiiiiM iiiiiiiiiiiiiiii iiiiiiiiii 11 lip 1 iiiiiiiiii 11 ill i i i iiiiiiiii in ill ii 111 ill i ii imp iiiiii
-------
Coal Remining BMP Guidance Manual
An example calculation of drain size in metric tonnes (mt) is as follows. The calculation
assumes a discharge rate of 30 L/min, limestone bulk density of 1600 kg/m3, bulk void volume of
40 percent, a projected alkalinity of 300 mg/L, a limestone calcium carbonate content of 95
percent, and a life of 25 years.
_ (30 L/min x 60 min/hr) (1600 kg/m3 xm3 /1000L x mt/1000 kg) (15 hr)
0.40
(30 L / min x 60 min / hr) (300 mg / L x mt /109 mg) (25yr x 8766 hr / yr) f
= 232.6mt
ALDs are located down gradient of the discharge point to allow for a free-flowing, gravity-driven
system. A sufficiently wide and deep trench is dug to accommodate the amount of limestone
needed to provide the desired detention time to yield the maximum alkalinity. Dimensions of
ALDs commonly range from 2 to 9 feet wide and 150 to 1500 feet long; however, much larger
drains have been constructed. Drain depth should be enough to hold a 2 to 6 feet thick layer of
limestone with sufficient cover to preclude infiltration of oxygen (Nairn and others,-1991). Once
excavated, the trench is filled with crushed limestone. Brodie and others (1991) recommended
that the size of the limestone be 0.75 to 1.5 inches to give both the needed surface area and
needed drain hydraulic conductivity. Purity of the limestone should be as high as possible to
prolong the functional life. Use of a low-purity limestone would require the drain to be larger
and more limestone material to be used.
Mine drainage is piped into the ALD directly from the source, before it has been exposed to the
atmosphere. It is common to dig into the discharge point and install a buried collection and
piping system. The drain inlet is usually at the base of the drain to maximize limestone contact.
The limestone is covered with 10 to 20 mil (0.01 to 0.02 inches) thick sheet plastic followed by
geosynthetic fabric to prevent puncturing of the plastic. The fabric is then covered with lightly
compacted clay. The plastic and clay are emplaced to inhibit the infiltration of atmospheric
Passive Treatment 4-7
-------
r ''
- *J
IKMfc ililii):
Ill ฃr
i 'll'ilh HIIII' !l!i','.i1!,1;; I'm1
oxygen. Clay is then covered with soil. The clay and soil should be at least 2 feet thick to
effectively prevent oxygen infiltration. The surface should be crowned (mounded) to inhibit
......
'.,(!,: ..... ' ]p;! .Ili!1!!.
^ .....
' '
f ปป,)ijj ........ ; illliil'.'! III!!' iliiiil! :: i , >'!> . i' ......... i!!, OHf iK i .; '( JTr j ......... !, ;. > < J!!I!(i( > IE' ifiS!> ...... !:!! 'I, VS-K! 'S, f:!K5 Jซ:;i. i,"A :!i : '^
I ;, , t ..... if ' ซป IiK jlilllB illliBF J'iilit:' |
I dissolves. Brodie an^ others (1991) recommend that the drain should be rip rapped or vegetated
With a plant species that will discourage the growth offerees, such as sericea or crown vetch. Tree
iH :," fte^Mft'lB'^'Cy^^divKlj'';^^! ra::&ai!tli,t:.;M!:"PVi^ซlปti-: .#ll,?il i!II.:;.i. mm ItiilWI HlSff: SftSLlf..^;. I!',18 I " Illllll m,W
$jฃg$P!J^c^ Thequtflpwpipe is installed at
iin, *;,, iifiii.ii'iiiiliiSi;' iiim; kiliii,'dtMtiHwliMiiMf iai>.'it M; *i s:#:'$:ff'-:::'.,! yM^KHI&ii-lKFMillitllf! i:i,flii!|,iiiiSiai,'! msxaK.-$wx,,;,*ป, n?'&ง&?, OK**"
the top of the limestone trench opposite to the inflow point. The outflow pipe is equipped with
w^Mr^tra^lto^revent oxygen migration into -the drain. | The elevation of the outflow pipe should
be below the head elevation driving water through the drain. The inflow and outflow piping size
should be large enough to permit unrestricted flow for the highest projected discharge rates.
, i,
t, ii! ISTIM^^^^ ilr>! !
Illllll
III)III 111 II
ill I" IIII
111 1
;.iฃPAQeJkQ;fflate.j g^its the drain and is subaerially exposed, dissolved iron and most other
^disSftiyedJnfi^S in the water will rapidly oxidize and begin to precipitate out. It is
en2^i^iat the water be diverted to a settling basin or pond sized for this purpose. The
Ill I! "in1 SiT.li,1', ffliaifii ,'"' ,'ii!!!,J
settling basin will greatly extend the life of a constructed wetland or other subsequent treatment
facility. Ideally, the alkalinity yielded by the drain will be high enough to neutralize the existing
iiB r*ir^ro'dM iiife, ti.1ilM W^ii'l'Ii'''*^^^^^^^^^^^^^ .I'lKlt;1':" iliiilliilii?:'!!!:11':! ',).i-r .ii VWiIiM fiitii):...'
'concentrationsof dissolved aluminum, because aluminum will also precipitate out in the drain
j lib Jll1 litiilt ^fงซ1M*' El I.I.I A-WI''; ; :l lii .ililii ! ,,h i< L I! i!:!i!lll1ti..liH^^^^^^^^^^ I : IIIIIIB sa: liiiii':* w:. .;,i,: ti::, n 1:1 K >:... t h ^ ? :i>!ป:!! iiii.: IIIIB :
... , , ,, .
'' llllf I'llll'iijii Jiill!1!!1'1!!1!!!!''!1!!!1 "JJilligillHIIIIIIII".'"!!! "AllllllllilllllllPI!"!"!!!1,!,!!!!;!! illl'i.JllilUiPIP.JillllPWrlivlltiillihli ..... iiiliPIPIIPhJoiBiPIIBII 'llllil1' " ft'1'", ILiillil'!', Mill ..... lilllllllttlilll1 PI'rillllLJ'lUlllll ..... nii.'l,!1' "LJIIMHiillilMJii'il'TI jlllillllillillritlillliJl'.iniMlillnlliL IIT'iiliiL',!!1*11!!!!! , >n Illllilillli iiiiii'iiiUM.'il'liiPIIII ..... ['niillilii^iiiillilPilf W* IJ ...... ..... "'I'liiilliU'i.iiiLLHillillllilir'n.ii,'::.,.!,, , / Jkl1 ...... II ' j
rdj'ffde' 'the ^pH is raised with or without oxidation. It is not recommended to use a dolpmitic
laiiiiifiriiii'iiiiniiiiiiiiiiiiw 1111, iiim, 1111,11:1,1
|i|||||'!!!||i. ,| 'ii||.i!<ซ: lll'T'ilillPlll!! Illllll ll|i'"i, 111 HUIIIInii I1' 'i;illll!|i|i,|iil'ii|i|| 1 I'll1 'il'll'l1 11 'i ij.l'llllnllllilll"! 11'1 '<,li, n1'1 il'lijilllllil'li',!!!! ! I 'P1' ,,,|, 'IIP PI III,, iIPP" Jill ,"' T, 11 'h'li illPPIiin1,
g(CO3)2) is much slower than calcium
4.8
Passive Treatment
IMIiilli i I 1 II h
-------
Coal Remining BMP Guidance Manual
carbonate. Therefore, the effectiveness of the drain would be diminished or the drain size would
have to be increased to accommodate the lower reaction rates. If sulfate concentrations exceed
2000 mg/L, it is possible for gypsum (CaSO4 + 2H2O) to precipitate within the drain once the pH
is raised and calcium concentration is increased (Ziemkiewicz and others, 1994).
Constructed Wetlands
The possibility of using constructed wetlands to treat AMD was first indicated by observations
made on the treatment of mine drainage by naturally-existing wetlands. The flow of AMD
through Sphagnum moss bogs illustrated that iron and acidity concentrations could be reduced
without degrading the wetland. Studies on naturally-formed wetlands treating mine drainage
were initially conducted in Ohio and West Virginia. Both studies showed that iron and acidity
were substantially decreased and the pH of the water was raised after flowing through the
wetlands (Kleinmann, 1985).
Because of the beneficial effects observed at natural wetlands, numerous wetlands have been
constructed in attempts to treat acid mine waters passively. Sphagnum moss was used initially
because it was observed to be successful in natural wetlands and preliminary studies showed that
it can remove large quantities of iron (Kleinmann, 1985). Near surface oxidation and sulfate
reduction in deeper organic-rich zones also decrease the amount of iron in wetlands. Later,
cattail (Typha) wetlands were constructed to treat mine drainage. This change in vegetation
appears to be related to limited iron detention from cation exchange by Sphagnum moss and the
high sensitivity of the moss to wetland water levels. Studies showed that most of the iron
detention in constructed wetlands was due to binding to the organic matter and the direct
precipitation of iron hydroxides (Wieder, 1988).
There are two ways that constructed wetlands treat AMD. First, aerobic reactions cause oxidation
and hydrolysis of the metals forming metal hydroxide precipitates. This removal of metals has a
tendency to release mineral acidity and lower the pH of the water. Aerobic wetlands work
primarily with mine water flowing through at or very near the surface. The subaerial exposure
Passive Treatment
4-9
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Coal Remining BMP Guidance Manual
SniSIH ';'!
1. I" Me !,,! ..... W-tl ,'! '
ilfi.'1:11!;];- Sif *M
pSriiiits oxidation of iron and other metals. However, in order for these wetlands to work most
efficiently, the water needs to have a pH of 6.0 or higher and a net alkalinity. At a pH of 6.0 or
higher, the rate of iron oxidation dramatically increases. At pH levels below 6.0, manganese
oxidation virtually halts. As these metals oxidize and hydrolyze, mineral acidity is released and
ill decrease. Therefore, the more efficient wetland systems will have an excess net
1 "Pllil'il, ijiliill'11'1 li''!
iiiiilH liiiiilidiiiiiiili!
&lkalinity in the water prior to the precipitation of the metals to buffer (the ability to hold the pH
iij^elativejy steady with the addition of an acid or a base) the release of mineral acidity.
ill liiiBl'li1:1' '' 'III,,if!,1 '',"
Illllli!,1! lli:M|!|! i i, ii" IvI'i'iKjIllullHIIIIIIIIIIIIII "UiniM iM'W,! : 'I'll! r,1, ,|'I," i.irvi," ' , I'lirm, ii||,!,W ', ' ' ," "III IP'TI i.flllli:1'!, 'nil' lil JllllliW- "'ill' illHMIII ! '' |,i' I1 ili'l'l! I '!',! II, !, ,!:,! nil, '*!, .!' i1 ,,,,',, -', ' BLIW! "ffill
111:.. ,1,1 ! il'll! [IB IlllllH^ lilllllllllll', '""illll'Tiii f>'' 1,1! .. I1'* ! lull,!,, ISf,1 "! I: I1,, , !,: &',,'" i III ',i' I !!!; '!!!<', .''! , .11'' f'ICli' :!Hii!!!i Bllill, llJilllHllQ;' ..' "iMIiliS 111,1,!: I' vA: ll .. - Hi.; ' ,; "':' v:,)!l' il'Si' 'ill,!! I1: ill
Second, anaerobic reactions that occur under anoxic conditions cause sulfate reduction. Under
{lliUiikilllli!,,,!!!! I
'i 'Illllli! Sill
conditipnSj_ metals are_removed in reduced forms,.(metal,_sulfides),, and, bicarbpnate
.Zifalkalinity is created. Anaerobic wetlands, also called compost wetlands, support reducing
''llllllllillliirfilgfllS 'Ulllllll!!1 !, 'Hill Jllllllilf1!!!111 Will! I'lWIIIIlipT ' ,& , i, | , , , r,,, H ftปA ,. l,,,,, , ,L,>V*
i'1,!"!,( ;:iiii npi!>; /: 4 [ ^ jniis, |j, ijj; ii iyii iii' i;: i1:,:! TI i:y n if '|, iipis1,11:
conditions within the substrate. Sulfate reduction by sulfate reducing bacteria (e.g.,
' ti'^'.EJPSSIflfovib0 an<^ Desulfomaculatum) is one of the primary anaerobic reactions (Smith, 1982).
Sulfate^reducing bacteria thrive in anoxic environments, feed on organic material, and utilize
t^Jate m.their ..... respiration processes. The organic substrate acts as an oxygen sink in natural and
! ..... "Sit; '':;:*.'?;j6c?61^eit?^s^^a|i^, creating suboxic or anoxic conditions from the bacterial decomposition of
the organic matter. Oxygen in water flowing through the organic substrate is rapidly removed.
!:,,,ง :;;,;!-; ฃMffi"si^1jilgri^uctibnj gy^bgen' ^jggg gas"(||2s) Is created and a'variety"of ^^"g-jg^-g1^ ^
':-iif' ^i^wiJs'siW^
pyrite (FeS^), iron monosuliides (-pes^ ^g jformecj and deposited within the substrate. Wetland
e.g.,
I
v systems designed to force water through the organic substrate promote sulfate reduction on
a larger scale. Iii the process of sulfate reduction, bacteria use organic carbon (CELjO) and sulfate
^ i^illlll iiiiiiiiit'i1 IB ii'Viii'; la i] Hii'Mi! 't-iiiiiiiiiK^^^^^^ iili:,!:!^^^^^^^^^^^^ :iii!ป^^^^^^^^^^^^ |
|SO^2"),^producing^hydrogen sulfide (H2S) and bicarbonate alkalinity (HCOj") (Mclntire and
Edenborn, 1990) as shown in Equation 2. The production of bicarbonate alkalinity neutralizes
I'lJin 'Ik ii!niini;iB!!ill!iiinnn!ii!i!i!ปin!JiWiiiB < iidii'iiBiii' iyciiHii.iiiiHHH:;: HifUi'iHi! v ^ \st,, >\ ^iPiiip'ii.ipni'iini." iin'Pu.np'M:!' ,v .niiF,1!,, I'l'Liii/iifj'. P' mm <"'ปmn !"!' ;, \<\ 111111111 i, nuii!!1 ,,- ,,:i:<.i!i!.| ipinng; , i,", i^ 9 ,- ini:,!!!,!!
IlLmliriilililliii.1 IBIIIillii'iiM1" Will I
,^Tf,!!::;;;;;;;;' ,;:::"' ''iricidity and raises the pH of the water.
liiiiiiii' i T'liiiifiihtiii; ''B>' tiiiiUi. ii'xfi /'P! it; l
' '' " ' ""
M^l/fiPii^ ป.)iS,C?IEO"-i:'S'042- = H2S + 2HC03-
(Equation 2)
1
There are a multitude of configurations for constructed wetlands. However, a few researchers
" : : I , -.:
have developed criteria for wetlands sizing and design to maximize AMD treatment. Kleinmann
' i
(1985) suggested that 200 ft3 of wetland are required for each gallon per minute of discharge.
i
'Mi,,1!,!!!! IUlillJ.hiiW '' 'I ,'IUP'ilP 'In"'M 'lllliTITiiHliilillin'i! I"!,, '" Wli" 'i"Sl^-TJjIIUMi,;! , i|
<: > i i
t iir iii
!,; I1 ' "I, 'II !
ill!I"" 'rill!111 ill!1,1. I':]!!!1
-------
Coal Remining BMP Guidance Manual
Kleinmann indicated that constructed wetlands may be most applicable to discharges of no more
than 10 gpm, a pH over 4.0, and iron concentration of 50 mg/L or less. Attempted uses of
wetlands to treat discharges with water quality or quantity exceeding those criteria were mostly
unsuccessful.
Hedin and Nairn (1990) determined that loading (mass/time) directly related to the wetland
treatment area was a more appropriate criteria for wetland engineering. They developed a sizing
formula based on iron grams per day per meter squared (Fe g/day/m2 or gdm) of wetland area.
The method also factored in pH, flow, and iron concentration. A sizing criterion of 10 gdm of
iron was determined for water with a pH of 4.0. For water with a pH of 3.0, the efficiency drops
to 4 gdm of iron.
Kepler (1990) observed that there may be other factors that also play a role in the efficiency of
wetlands to treat mine water. He noted seasonal variations in the treatment effectiveness related
to variations in influent iron loadings as well as treatment area and biological efficiency. An
inverse relationship was observed between the iron load (ferrous and ferric iron ratio) and the
efficiency of the wetland. This is related to the flow system through the wetland allowing time
for aerobic and anaerobic reactions to occur. He indicated that the flow system may be as
important as the surface area or vegetation types. For overall effectiveness, a value of 15 gdm
was determined for year round treatment. A sizing safety factor of 1.25 was also recommended
(Kepler, 1990).
Stark and others (1990) in a study of a Typha wetland near Coshocton, Ohio, observed a
consistent treatment efficiency at 10 gdm. However, the site averaged over 13.5 gdm. They
likewise recommended that wetlands be sized to treat the maximum loads anticipated.
It is critical that accurate discharge flow and water quality background data are collected for at
least one water year (October 1st through September 30th). Extreme care should be taken to
ensure that flows are accurately measured. Wetlands should be sized for the maximum
forecasted flow, concentration, and load, so extreme conditions can be successfully treated.
Passive Treatment 4-11
-------
i-illi!1'1'11 P.i4HUfllB't " 'tliiilU irK! '
f l>ll!"!>!] ' i I! !"( ...... ', "J ; ' Sllli1,1, '.HWWWMt ' ........ ill ..... lit!"' ........ Ilinilliiii,! t lilli'ia'it'l ....... 111! ..... ..... ;!!3!!HPll.i i.iiBi'Vi*!!'!!' l
ill'lllll!.: ": !'i|1r: . '.I'll'I! .I'll" < !"l
lllllll 'ifl ii"!"".1, [:,';!;.:i,iii, ;. nip
!> :,!"">1 o11:^ inhiC'i,;
. jป'jCocd^ Remitting BMP Guidance Manual
np :i'i in i ;n!i i>4 ' i ปt niiiinni ':' i 'i :!l ...... inn, J!II:H;IW ....... LI i
Bill'1'1' ii"!1]1 ftPi lliilillHlll lil'lllll illlliE'i'i'lSli , W. 'HE' "I li'l, II MTWil lป!ปปil,,, i,'' i"lซ. .:'' i'l, n ,1 - Mil'.' illiaiRilK
JBJ|; .'Vr^iSi^^WHgK co^gi^ation of constructed wetlands can vary widely, there are some basic common
ii i jiiiiiiiE miir n minir,, ah <":\ :' jiinmi" M ซiif *' FII it
ji vMRjiitjy:
-F ; SnSSfif iIMances, fee_mine discharge is initially diverted to a small settling pond. Depending on
ii iiiiiiiiiiV "lyi'iir/'Hi 'iviiniiS liiiiiiiiiS^^^^^^^^ ป ''Miiiiiw^ ilm. i 'I'iLi I'M.!! i' "liiS lihi1 ''. oli'iiit ni ihiiiiiiiii'i^^^ 'Luifijii;! ii; iiiv i: i" pp. w'niii. ii'ii1 ''Niiini i,"iiii:i! viSii'iniiii^ /wi'iw :.ซi tiihiiiiiiiviii
;!' (||]|,l!:Jil<' , , i'lllllllll lilIB'f!,:,' '"{ifJlliffl >' I'!!'*! I!" Ulllll!' it !' ซi f i.; tail' Illlldl'':!:'!1'! j1" iซl"l"!'l' J'Klt lii^llillhliiti,;!!-, .INCI.I'IIIH^^^^^^ f lilliTiM I! I 'IIUJSIW : > i,:!,;' .tililllt.!)'!'!
sKig.pH and alkalinity of the water, some iron will precipitate within the pond, extending the
it IlllilliR ^ Jn ill"!1''''! IIIIIB 11II llllllll I IIIII Illlllllllllllll 11 III III I I I ill I 11 I III ; till t ; ;i!l n ill WE11,111''" hiftilli, i jlllilliNl 9^ ti'! P'lllillli rniilllHIl1 :i:^ ": Iii
llllliilllll V f :.il|llf. "' 1 , liiH, '.Iilllll i; I'llilH.: Iff !;^ir" ป' ;|i ;ii I Ifc "i1:"!! i'' "I Si!, f I III1 111
!^^^^u^^^^^l!^ life of the wetland. The water then flows from the pond into a large wetland cell or
Illil.T,;,!i>:' illllM^^ iilllll r;,;!ซ./1 !i>M^^^^^^^^^^ IMWI "i'siHi" i^aPiiK IIซIIH^^^^^^^ iiiiii'raiiii'H^^^^^^ M^^
_,. s" Figure 4.1b is a schematic diagram of a typically constructed wetland system. In
liiiliii! i ii m^w&wm?,'immm Hmnfitij
IIH1,11 liliiii' I I'liniiWE ilillli!!'
Illlini lillllllllllllllll II
ui: ^Ji:: .Illlg ..'iilllKS' vcji
i ..... :!IE:,,[:|
ป'., I'J v
llilllMDIIlP! :a\\V\r ..... IllllllllllllllillllJIIillnilJ '"Ill' 1 '
^.-f^rsi- :l*,r,.: series of cejls. The water course' is designed so the detention'time is as long as possible to yield
" ;1!;;;; ' maxiifiniff^eatmCTLt. This is usually accomplished by the inclusion of a series of baffles to divert
r ?i: : the water along a circuitous path. The last wetland cell is followed by a final ccpolishing" pond to
I ......... IJUTIk'HIF" IIIIO'l ....... iJllilE'TBil1!: V! Jill! ..... IK "1 111: .:i!lr:"lil::< ! ..... I-1"!::: ^llllld^lllR!l!lllS!: i! I"! "" 'i "IE ......... Ill "11" fill! 'I'll rilir
- - -
'XiliJiJIllillll! ..... filUH ...... fyi'lil'iilE,;):1! ..... Ill rEillil !> t., ' 'Hull!; IRS- iilllll I
if
i.lj::! ||ing|ting apjplicable effluent standards, is discharged to ^the receiving stream. If effluent standards
:, , iiiiii'are not being met, additional treafment may be required.
ir JiiiiiiiiiKJiini ,"':i .iihii,' JS"J
Figure 4.1b: Commonly Constructed Wetland Diagram
11 ................ ...... ' [[[ - 1 ป" '' ' "''i11 liU'i,1!,,!!";1" ,!'.;: iililRi H"!!, ..... l:-1 "'ill! ..... nJIIIILIi!!!,1. Jl lllhll1 'iin.
11 miiniiji11" in iiiijiiiiiiT:!!'. ii' ,,i 'Hiiliiiil, "i'1 !
IHS/'jiiWl"**: II
0 , PjllU Plllll iiluU1, llllll'J ii , Illlllili'I Ir I1'ill i ," ililliill' 'lihllli'IIII'illLi i I
\
J
-
Pond k=
iiiiiiii ) ii1:,: ;.i,:1: K-a i: .iJ*:'
LlWK.'i'CIHlMi'SKSIKaNpi'".!^ If
!i1";:: , 'iii:"",! I, i, f '
: ::ijl|ll,:i:|i'. "^jrjf:9mf^il' iliyj11^,i^jtjji^l^Jx) ,\,;: ;:l;i|||.- jiijj.jijf!JJJBIjftjf,"1:1 *' I
^Sn ฐf individual wetland cells is directly dependent on the amount of flow and
chemistry. Brodie and others (1988a) based the size and number of cells on the projected
illf Piilf liilii'i: !!! ? Ill* IIIIIIH iillllM lailill 'MiaS!:* ^iMlti, tliifif: i Kill'1' ii 'filfSSi i
-------
Coal Remining BMP Guidance Manual
dimensions are based on the treatment area needed, maximization of the flow path, site
topography, and configuration of the available space down gradient of the discharge.
Wetland cells are frequently lined with an initial thin layer of crushed limestone that is usually
about 6 inches thick (Figure 4.1c). The limestone is covered with a thicker organic layer, usually
12 to 18 inches. Mushroom compost is the most common material used for the organic substrate.
The cell is subsequently flooded with 6 to 12 inches (15 to 30 cm) of water and planted with
vegetation. Cattails are by far the most commonly planted vegetation in constructed wetlands.
Other plants used include, but are not limited to, cattail-rice cutgrass, sphagnum moss, rushes,
and bulrushes (Brodie, 1990; Brodie and others, 1988b). Various types of blue-green algae
(Cyanobacteria) have also been introduced into wetlands in attempts to improve efficiency for
manganese reduction (Spratt and Wieder, 1988).
Figure 4.1c: Typical Wetland Cell Cross Section
Cattails
Outflow"
^
-^
-^
^ /Water
^
ic Substratf:
~.~.'
, -^.^
'sf*x ซ.:**">
-Inflow
There are limits to which wetlands can be used to treat mine water. One of the most salient
problems is the amount of area required. A high-flowing, high-iron discharge requires a huge
area for treatment. A low pH (<4.0) water will require more treatment sizing (4 gdm) than a
higher pH (>4.0) water (10 gdm). Using the sizing criteria developed by Hedin and Nairn
Passive Treatment
4-13
-------
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U SSESง Ssl ง3i^ฃง3L,0,0.5,AfiE^,fbs.ง,pH under 4.0. However, Hedin and
i;iiiiiiiii;ii (HI lawntu'r.'.**: Biiei*m/KmK\mtu- HjwMiixifHHii^uiHtuidVHttiMiikit*1 :itif.%* r IIIIM^ 11111: I
1990) stated that for "highly contaminated drainage," a larger wetland sizing criterion may
I'iillH^^^^^^^^^^^^^^^^^^^^^ . IB IIP 9iii
a pH of 3.0, the wetland sizing may need to be increased fry 300 percent.
The performance of aerobic wetlands is greatly hampered by low-pH water. Raising the pH prior
jliiiliiH^ {''IIIILJllj"!'!''.!.!''"!""!.!!!'';'!! ,' ;lll";,l^7i[ซ ijiMiinniiiiii! :i;ii,i,1* I'liiiHiiinpiiii;' 'fiiciii'inirSLiia:"!;:,^[iai/iiLaiir'iiiiiiLJiJ:!1! <. :>";!iiii!iiiiii'pi'iiซniinii;>.iynij:j:ii;iii:r;iiii'iiiiiiiiiii!iiiini!'*ป,IJi"BiiMiiiipri,,1];:i :ป',"viniJHiiii1;aiii^'iiiiiiiiiiiiwiHiiiiiiiiiiiiiiiiiiiiiii1111
1 "^design, iron hydroxide will precipitate within constructed wetlands. This precipitation will
ซ,~..^.~*/ cause iron hydroxide sludge buildup in the cells, which will cause changes to the
ilW^ t'lAi,,: ;1K >ป!'! liii''!'''!; i< iTniiiiiiaiM^^^^^^^^^^^^^^^^^ i'mi iiriiii'ii -fit MM iiiiiiit i-iiS'iB 9iiii!ซ^^^ |e:i(iiป^^^ ii!;i'''K^^^^^ I
IJwatef levels. These changes will adversely impact the vegetation and decrease the wetland
.treatment ability. Also organic material will eventually be depleted through bacterial action, and
require replacement. Depending on the flow system, the limestone may also need to be
^ as dissolution occurs. Therefore, over time, wetlands require periodic maintenance
IS ..... a I. - ...... i!!
~i^;'; ;;; :^r ; Etp'remoye'IEe, IiMi,'h~ydroxI3e sludge and replace 'subslSaTe'matenaTsl
m^
ipiyii sr ':;|iiii: i f^ucc^ssive Alkalinity-Producing^ Systems
! 'Hinii I 'iiliilllll|tl'li!'i ,"' 9'KS "'"ILi,::!!'' i: i.ll ll&i'lliil ilNii' ,i?; Jl'.. '! illilil! "III! Iii.! K "iiB!! JCXHH'fflUKa "iJn 'liH:' I!"'1' iililli'IT 'i!i"]iiiiiiii::.'llli!i i:'"' jii SliiEilillillt'UliK 'illlilli'''' lli!, tii'lii!1!1'':!!:'!:::!!!' Hi llliillil'i'V!', <: iii'! .il!!1!"!! .'i'i'lli'' 'f i IIIUIH Illllliii!'1. ii'!!:
!g|ปSIS ^/.^^fif^lffid^the^^uirement of ferrous iron does not apply. An oxygen sink is created by anaerobic I
Illlll iliyiP'n i'l I'llill,' 'i'lhl'll
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i: a iiiiiii'' iiyip ,( ivmnv. iicii "inn:ป' . i!. .f ,' nif T ;,!; !"'," *; i, m w,w.-. :,i!S"; Si-in ti: i1: ,1 .::", 'Hi, n ^ffi.iw in", "UK :if." !. ". ',ii.; .
"r::ii iiifai':1! 'I"'! r11*.1':1!!!!1!!! 'Will!'!!:' ''i!! ''I1: 'I'11::'''.:'., ' :"i": ":i: i'li i i:>:. ,< iililLiil't S'i':.!!" liiijliii i't lillii'ijiyf'"" ''imiiiiirai:''11'!:,!1!'1'!! K'liiLiii! ''ml fiiiiltiil!!'!!!1'' }{, 'illpilin ill iiilEB^^^^^^^^^ 'iiii
. lllll,: > ' 'i9ป9Si> 'lit I ''!<" '""li^>,.!' 'if ill!1 ฅ-lt .irJ' lil':<'lH: S:: if 'l Xlliil'; -'.'. i"'!',;!"!!:!!!!:*!.' I, ''ilSlilllif!1)': Jill1- I'SK 1> lilllP:,: 'Hii i'"!' Iiii lii'liii >: I? "f ::f:ill"": 1 IIH^^^^^^^^^^^^^^^^^^ 1IIB III
, of ndiidualSAPS cells issiinila^to^a^^ajcpnsjructed xvetlandcell^ butthe.
Ii: ,,ff'] ii,,,[i,". i1;"Fiii!"!';1 ,iiiiiiiiiiiiiiiiiiiiiiiini> ;n i, iiniiiij iniiiiini / iniiniinii TIII <,; 1*1;' T , u,, HP i iinnm:,! M >,ป., T . mi >. , ซ i vr, i m, Ami 'iiimi n>iillllll:i<. i"i, nilllllllllllili"; i^illlilHIIiiiiiill i'si iiiili'lll"'1'" ijin ."PiFllLlliniiiP"; P iiil|ll|ii:ilIllll I11' ' in!" "I. >l! '"'iillllliilli1' .n'liriiiiill'illlilPI,1 .IIHiiilLiljilili"''!!!!!!'!!'..!.)'! iliii/il1'!! , I'm nllllllbil'llllll ' l'li;i!i!||i:illiiili'lilliilll|i||||IVIjiil''!iiii:iil'!^|l|lllllllilll|::illlllll^ ll^lillllllllll'inilll'li'iliiii'illllllijlllillhi'llil'i: liinilHnlltFiilili1'1 '!<< 'iP'1,'11 .Wiiiiii!,.'1*.illliililiAilllllllllllllllljiilLliiiliiillli
that produce alkalinity, there are several configurations for the entire system. Kepler and
im :i:i!i:i;iiiii,ipl!:iiii!,Mi'ii!iinซ jui11!!;,! IIDn j' nm T
til! "i| Si'iii! I111!1"'illlllili1'I'lJ'ini.jiinll! I'll'|iii
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-------
Coal Remining BMP Guidance Manual
McCleary (1994) suggested a configuration of an ALD followed by .an aerobic wetland or settling
pond, which is then followed by a SAPS cell that discharges into a second aerobic wetland or
settling pond.
An individual SAPS cell is designed to accept water inflow at the surface and drain from the
bottom. The basal layer in a SAPS cell is crushed limestone covering perforated underdrain
pipes (Figure 4.Id). Skousen and others (1995) suggested that the underdrain pipes be covered
with 12 to 24 inches of limestone. However, Kepler and McCleary (1994) indicate that the
thickness of the limestone layer is based on the detention time required for maximum alkalinity
production. A similar amount of detention time as that required for an ALD is recommended.
Four SAPS constructed in Pennsylvania had limestone layers ranging in thickness from 18 to 24
inches (Kepler and McCleary, 1995). A layer of organic matter, usually mushroom compost, is
placed over the limestone. The thickness of the organic layer, like the limestone layer, is based
to a large extent on the required detention time. Kepler and McCleary (1995) observed four sites
in Pennsylvania where the organic layers were 18 inches thick. Skousen and others (1995)
recommended 12 to 18 inches of organic material. Overlying the organic layer is free-standing
mine water. The depth of the water is dependent on the head (pressure) required to drive the
water through the organic and limestone layers at a rate that to adequately achieve the required
the biochemical and chemical reactions (discussed below). Kepler and McCleary (1995)
indicated a depth range of 5.25 to 6.23 feet was adequate at the four study sites in Pennsylvania;
whereas, Skousen and others (1995) suggested a water depth of 4 to 8 feet. Size of the SAPS is
based on the required water detention time, which is related to the flow rate, more so than the
water quality. The rate of atmospheric oxygen diffusion into a body of water is relatively
constant and should be used in determining the areal size of the SAPS cell.
Passive Treatment
4-15
-------
HIP; ;ซซ":! i;'^iu tiiT yen rant v an
>in!il'ซlllป^^^ :iillllllllllllini."l|in,|i!liil 'ii lllii,<:;i,,lilhi!;i ",ป i'i' ,1
i , , ii1' isi'ipi11'li: ,i:i n A H IT* a iiiiR1'!1;:!! V'lin HUM #*,9, -vwiv , i' 'iniiR i m m , < miiiiPi! r "T'! liiiHiiF i, i 4N v\, >'
"!''ill*,: iiiii1 ,,iihiii!" 'i 1,11 ii,1!',,'"'"isiiiii'i i11 ii ' ,!"",,-"I!"!,. ii'" '"i iji/qi'if".'! ,,,,'ป,; ,;i,i jui *'i ''iii'i1"'"1 ua^, i, ",i,ii!,,i iiiii'i,i,i< ,i'iiiiiiin iiiiiniiiJi ,i',* .iivpi
: i',:;1!!! I1,!' ^'lilillll'ill!,!1!;" ,"ซ -'' '!, ,ซ ,kiii;ii:il!il1ii::H^^^^^^^^ ,,'
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figure 4.1d: Example of a Successive Alkalinity-Producing System Cell
iliilH ii:i!!H ii^flili'iilllK^^^^^^^^^ '' i'l ''^ilii !JilK^^^^^^^^ III! IrfRiit'ilii JiftM^^ ij(411tin *!";fl-i*'1!:||:iWMซ l|liii'i::,i;9(](!K i'ii-illi'sSIM^^^^^^^
fiililHiiii 'Iliillll! ii: i ~ lllllil I'll 'iiliiiini i ii! ,i- fllCi,, flllll -i ililllli' ItH-' ii ' 'illiiiF::!!!:!: /I'R1 ii'iiiH' if'' ill" '"iit, i JtlilLiiMia '": '' 'la/!'') K liT I'S'U" i';!":!, Hi -iluHUiit illilllil'', .i..'.:!' "-1 i-ltti 4)'' ii(:!'! i't iKlit 'i1!-' IliiiliB^^^^^^^^ i i >''iiiii'i'll iii/lHIIIIli*^^^^^^^^^^^^^^ IIIIlFijillii: I
iiiiif B itjij-iniliilii 'l-iiir1: yici^d^ ilii , H: .i-fai'^f''^'!!?^ 'A, f 'a.:>i'!: ซ8;>ifr', i iv''^^?^! iitifiil;i4:l!ii irl' 'I iliif-iiv-^ii Fliilliliitiiiib: I',;!1''; !i,ttf>i>:, i ii! ii
Kป in; in1 ijs 1111L- tfi!1 ri'iii, i, irtiii' vtfi ' liiiiii:;.:' '" i.i i'> !'.jiiiO-i inis' i"'1! >; ) *' '.. ii1! :* -KMiii; '>' , "Mf'-1- f 'j<''*& ' ',; >, .Si viKii ; >* : I'll" '. H nidiii!!!!;!!"ป "' 'iiiIPI '=< ":-ii|.*ii f\
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,<: "I .!!,<: ,1 ! I, IIII '< i /mm,. < ' i' Jlllllllllliinl nlllil'iJi ' 1: i J1:1,1*! I'l "L1' J't1 |l'..
"'.;',|l!.ซi 'iMiiiBi.,,!'! J; ii, ;! 'I'1"!,:,,,;
l&'iTr^rtrrr :'.".".tงA?S function Sough a series of chemical and biochemical reactions to remove iron and other
; -;,,::: liSetals^fromtoe water, while _ increasing the alkalinity. When mine water is initially discharged
illiln
;JK;f t^S^SSi^ fiie, feslc, SIMS: JpSlS-Q^fes.6..!!^^5:.?, especially iron, will oxidize in the shallower
^ateran"d""precrpita"teon topbfThe 0^3^^ layefV'Kepler'ahd"McCle'ary'(1994)"observed'2"mc'hes"
|5 cm) of iron hydroxide deposited in a SAPS at a mine site in northwestern Pennsylvania.
:,,,!'! IllllllUIIri Mill ! i ,;, , '!: .nil!', l|!i I!! ill tVV V Jlf illlllllllllllllli1 'i"l : IIEIilllllKI ซ ill < BIIL'ii ป!Killliir illt iJllllinilii! iK'1!!, illIHIl > 'HSIiiPI1 ' ....... ( , II i1 'IP1 ii Jl 'ป ' ซn iiiii,! J'IM I ...... I niil1'1 'PVIi H'l , ,1: " ' ' 'Illl'i, '" hiilUilil I'1 "i! , ' I", liHiilllliliiiilll1! !: Ill1,;, IIDIIIil J ' III1" "Mil ..... I'lCIIIIIIIIIIIIKIE*!! : T" r,: in , li'll'li ' 'I1'1'!!!!!!!!!! vA ]\ il }" j ; ...... '' .iiLi'MB ,' ,,',"' ailO IV' ' I"" 1 1 !; i . '' ! ' ili'< , ,
'< ,J ' ''ilHililiil l< 11" llli, ill!' " In
lililliiSl !1l!iilii|i||l|il
Ilir1'!'!!,1,!!!,!1.!, ' IB'
l1', it's. T: ',!:: I'ti'isir':11!111!: 'isiiviiisiiiaii1:...: Ji- < f i <>': "Si "'!"! iit iii: f ;- i/ii"! !! i; ii :Gii.:if; :>|K' liii'S si; iiiiU!
i iilfi i:t i1! 'iriii ,;ป;:< i!!- Ji:;! iii'li''!9!:!;- i, i'' i;. I vniji: Jliilii'iis^^^^^^ '.Sit
Qnce in the cell, the water flows downward toward the organic layer and the water is rapidly
ed ..... o^ssjojye^^oxyjer^by^microbial ...... decomposition of the ...... organic material. Bacteria
iIize the DO in the mine water, to metabolize the organics. These reactions occur near the
al^tfeSS,,Qf^ie. grganic material and the water. Kepler and McCleary (1994) reported that water
iiiH ..... iiii'iii'iiiiiiiiiiiiiiLitiMii "iMiHi: ..... IP iiiii
: ..... iiiiii:,Li:j;j iinihf iiir ly
';"'; i <,illl< I'HiililB" nl ,: It1 i::;: 'ifill1 ii ""iiiliii: :iiii,,
-------
Coal Remining BMP Guidance Manual
anaerobic sulfate-reducing bacteria in the organic layer will chemically reduce the metals as well
as the sulfate ions, yielding hydrogen sulfide (H2S) gas and metal sulfides. The H2S will be
released into the atmosphere, where it subsequently oxidizes to form water and native sulfur (S)
(Lehr and others, 1980). When these systems are working properly, considerable H,S is yielded
and the systems tend to have an offensive smell. H2S smells similar to rotten eggs and is
unpleasant even at very low concentrations (0.05 mg/L). Metal sulfides are deposited within the
organic material, but some of the reduced metals will remain dissolved and pass through the
organic layer.
This reduction process also yields bicarbonate alkalinity to the water as described in the
preceding wetlands section. This process, in turn, will neutralize acidity, add alkalinity, and raise
the pH of the water.
Once the water has passed through the organic layer, it enters the underlying limestone gravel.
Because the oxygen has been stripped from the water, and any metals that are not precipitated are
in a reduced state, the limestone layer functions as an ALD. Passage through the limestone adds
additional alkalinity to the water through dissolution of the calcium carbonate, -as described
above under ALDs. If the SAPS are properly sized, the effluent should have a pH of 6.0 or
higher (Skousen and others, 1995). Aluminum tends to pass through the organic layer and is
precipitated in the limestone. Because aluminum precipitate does not armor the limestone, but
instead remains as loose precipitate, it can eventually plug the limestone layer. Therefore, a
piping system that will allow a periodic forced flushing of the limestone layer is needed to
maintain the efficiency of the system (Kepler and McCleary, 1997).
The SAPS cell effluent is typically piped into a conventional aerobic wetland or settling pond.
With the excess alkalinity yielded by the SAPS, much of the remaining metals (mainly iron) will
quickly precipitate out of solution in the wetland or pond. The process of iron oxidation and
hydrolysis will, as discussed earlier, yield acidity. However, the excess alkalinity in water from
a well-designed SAPS should perform a buffering action and be sufficient to maintain a net
alkalinity throughout this secondary precipitation process. If the alkalinity is insufficient to
Passive Treatment 4-17
-------
la!..,(;j fฃs(llฃs^linjgg BMP Guidance Manual
=ฃ'=;, Js, : ". Ji[neut^|jze t|je.acidity produced by the iron precipitation, the water can be piped through a second
Ii||I;.:.; H; - i, <' ilSAPS. This process can be repeated until the mine water meets the applicable effluent standards.
,. - ipyn: ,jF ,,-; B|.Lmiitations on SAPS construction, use, and maintenance .are similar to those for wetlands and
'!"!' '""" 'In1 I ..-I i' Iiniiiiliilllli1'1 t^Sj Iiiiiiiiiii' 'Wffl'WftllK Wi !il!":lEiti 'i1"1::!. ! i'ikil jfflNSHB'i! i1:!!.!,..-!RIB'1*' i*'iiiiiiiiiiiiii:-i!'ii"'! iiiiH^ 'If,'v JW;1*!1. iii iiilifi/'JR'!!1n|lป"'.iiii:i"iiiiiliiW' ''I'1 iifl.!i,i i1"1!* i!P''Sff "Mi! i.tlliliiilill 1ili rliiiiiilttll. ,iia^^^^^^^^^ ,i,:i!Hi: (.'.il'liiWIII nil.!'.!''.".'. ' Qr ;i : , ..(iiiitli" i Sni.'.. lllnli lajfiM:,:. HfilE'.!.!1 'I'll1! |
,; si fi'iijl'11;"; ^V^lKSiI'EJgs Restrictions to the use, of SAPSjnclude, but are not limited to:
EiiiiM^ iiii 'ii'1,1111 'ป!,.'ป!.. ': mm'f 'iI" ii'iin iniiiHii! ป;, i.iiiiH^^^ ':< 'iiiiiiS^^^^^^^. NMitV. .laViS'i. '^rSSi liiiiiiini '., ' .ป "ii'ii fi/ ปi','ilSri, ii;' iii i ibiiu iff" i .(iiiiiisiiiiiiiiiRiiii I
111 iil..''?!! if-i ;|K"1ซ*ซ,i'i!l;,1!Engineenng and sizing should be determined by the discharge flow rate. The highest
i:t5u5rjiซ .-iii"1;. B;i;Jftซ^iij|^ycipated flow rates should be used as an engineering guideline.
Topography should be such that the system will function (flow) properly without the need
It' ""iliii'lli!1" .I"'! I". IIII Jl.'.iiiilliii:!:1!'"" ill'lii.!.!1!1. Jl! >ป: i: ..:' "'"i"..."" ; .<"i ii'l..):!: I. '..ii'F" .i11;.:1:': (.'.iiiililHl 'Hiiii'ii.".; i]:iiiiiiiEi.i:.ii.]lPH^^^iB!li!i..> i. n" e IP .'iMiiki'...;:::.'.i!.'..iiBi:...:s|>>>!;it.i. iiSiii.iiiiiiN iiiiiiiiB^^^ I
i m/m :!.if|;j|i ,:i;ii.-!1.9^^^^^^^^^^ .ป^
ai'^.JIi ^ifcS")!!!? .f",'!'.Cis'ii,ThS organic material and limestone will eventually be exhausted and will need to be
niiLflniii i [i' 'Pimm:!,'! > . : iin t IB in1, iiiHiiiiiiiiiiiiniiii:! ni < Jiiiiiiiiiiiiiiiiini' , myaiii 'Mi iiinii1 iiinii i.ii m1 in'; Bi1 , : -v ซ> f' n:| '' B",iiii iiBf. i iiiin, ill '# '; >a >i ',n ir "if 'HiiiiuiF \- '.iii 'iiiiiiiiii': in i'lmi "r'T'iniiiii'iiiiiiiii! mil1! BIJ ;' < 'Biiiii nic, "'i"; \\n .*i: 'iiimmjmm i|.ii:!!ii.ป^ m,KK :f ^ f "i" i^ma i
11 "'" '"" ' '''!l '' ' '!" l||l!"l!' l!l " ill:l!1Ll '"!,. ff the iron precipitation within the 'SAPS is substantial, this will also require a
[
J!; , , , , ; ., r iis i, t, ^Cajcjum carbonate purity of the limestone should be the highest available to prolong the I
life and maximize alkalinity production.
.:::::: i::::;;.:1::.:;__:.. "'system is required to permit periodic flushing of the aluminum floe from the limestone.
Jjljฎ:j ST?!' srj ii'' 'SJSfef'ฃ LMtcstonc ''Channels^
\ i
In cpntrast to treating AMD with limestone in an anoxic environment, more recent research has
been conducted on this treatment in an environment open to the atmosphere (oxic). As
previously stated, when dissolved iron is oxidized, it will precipitate, armoring limestone and
4-JS Passive Treatment
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Coal Remining BMP Guidance Manual
creating an iron hydroxide sludge. In theory, limestone, even if completely armored with iron,
will continue to yield some alkalinity. Ziemkiewicz and others (1994) indicated that CaCO3 in
fully armored limestone is 20 percent as soluble as that in unarmored limestone. However,
Ziemkiewicz and others (1996) reported that armored limestone may exhibit 25 to 33 percent of
the CaCO3 solubility of unarmored limestone. They observed an acidity reduction of 0.029 to
1.77 percent per foot of open limestone channel (OLC). Though rapid neutralization of acidity
by armored limestone is observed initially, it slows with time, and exhibits a logarithmic decay of
the neutralization rate (Ziemkiewicz and others, 1996).
Limestone channels are sized based on a projected 90 percent acidity neutralization with one
hour of contact time or 100 percent acidity neutralization with three hours of contact time.
Construction criteria are determined from the flow rate, channel slope, and acidity concentration.
This information will determine the mass of limestone, the cross-sectional area and length of the
drain, and ultimately, the in-channel detention time. Channels are constructed with an initial
dam-like structure at the up-stream end to trap sediment and other debris and keep it from
clogging the pore spaces between the limestone material throughout the remainder of the channel
(Ziemkiewicz and others, 1994). OLCs also require sufficient slope, hence water velocity, to
prevent clogging of the interstitial pore spaces with iron, manganese, and aluminum floe. If the
pore spaces are substantially filled with metal floe, the water will flow over the top and be
precluded from contacting the armored limestone, greatly attenuating, if not eliminating
predicted dissolution rates.
Table 4.1 presents examples of limestone tonnage calculated to treat mine drainage with 1000
mg/L acidity, in an OLC with a cross section 3 feet deep by 10 feet wide. A mine discharge of
200 gpm and 1000 mg/L acidity would require a channel 3 feet deep, 10 feet wide, and 401 feet
long filled with 5,085 tons of armored limestone to treat 100 percent of the acidity.
Passive Treatment
4-19
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Guidance Manual
"ป=;:: r,i i Table 4.1: OLC Sizing Calculations
Iiii11!!!"1!1",!!,,.! f'Shili'lirill 'BBBir, : IIII
Flow in gpm
100
200
500
1000
Channel Length in feet
1 hour
contact time
67
134
334
669
3 hour
contact time
201
401
1003
2006
Tons of Limestone Required
100% Dissolution
1 hour, 90%
Treatment
169
339
847
1,695
3 hour, 100%
Treatment
508
1,017
2,542
5,085
20% Dissolution
1 hour, 90%
Treatment
847
1,695
4,237
8,475
3 hour, 100%
Treatment
2,542
5,085
12,712
25,424
Modified after Ziemkiewicz and others (1994)
: Hi
Ui< S* "
"! ir
Mi":
" ....... ill'
A recommended size of limestone gravel for use in these channels is greater than 4 inches in
diameter (Ziemkiewicz and others, 1994). Optimal efficiency may be reached with limestone in
the 6 to 12 inch diameter range. A channel grade exceeding 10 percent is also recommended to
li:l!t!K
I' BBIIBi ' , IB ilf
'l i).
,:j^[facilitate flushing of the metal floe from the drain, preventing a clogging of the pore spaces.
, llllllUlii! Si),!,Si!11 J:|!!!l|il:i,i!>:' ZlllilllP''', /iillllllliL i.Jllliiiilii'i,WjUM'illrtn MX It H , :,: fi WtlRi,i '! 1 .1 i'l! ' t ''Killlii'linii! I'ilili1 *ifflMfllM.'Siilil! OWtlUflUM : >'J11..I'l1;.1fllllEK^ ! SI!1'!" :.'
Channels with less than a 9 percent grade were shown to be much less effective than channels
y|i Ijjjjjjijjjjjjjil ', !i;liij1;ซ ;; B:'';;,i""IB|BI|:.., ;>,;jjiuri :: ij;! ',ii:|ui[',.. ;;|11< 'i>'BB ],' ;t;B'''v; j,;jjifT,",;;,;-;, r\r \ "iSiBfB;: 'if!iji|'j1 iiiiiPii;]';< 'jt lillBBll ijl? i ' ]!''!;'fiwiBiBiBB fBBRiii> ;i]<( 'ijjjli',:*?' 'SSi'S' ~ i!" -11 "'2" i!"^^^^^^^^^^^^^^^^^ 3DB;:
allow the metal floe to be concentrated at one point and should permit discharging the
lli|Ptn,i niliiinniil TWiiii! ,,'1' n'laillllllllllllB,!1! "i lllillilil; I'!'!1 ffnii"!!!11 ; lifl'i'T..!.!1 "j JUNi 11, 'O'/hll y>>\ ii Id! IM:" iiliii!" .Jli'i'l 'IILii:11 TiiiH":!,!!'11'! '!!'!'.lilil'1" i" ซ SiirjHiillil1" THIII" liJillhlllllllllllTITi'iijIllililiillillllllllllKIIVinlih',^ i:ป\"tซ\f" Ilif1?' lE'lllllilR1 iftliililiiii '" '
:.ncfdiripliaince water to the receiving stream. However, ponds will require periodic cleaning to
iyiiii i1, ii"
i illlfHB' f n'lViiliniii1,;;! "ita,,'1'1 Ii."ll.li: I"! i,1'!1!!!! !!l.
i,v ./'IPIIlin ..Ir1! .iniilil I
ll : B! Illii i i! , ii' IL Ji! >'!
i!;. ' ,J!I Jf il!!!|||r II I! IIL' ' iiiTIIIIIIIB ^^ ' F HI:' I1!;! .Jli "I! ilKB" ,! 'I ji II' L illh r'! " , . HI!"! liiiiil J! I1 T ' IL: ',, ii,!!! IS ii''1 1 ,in I " .n,JI!j,, ;ln 'iiii/1.:;!' i^1' ?': illlil i; ji!l! j1!:: ill1 h:B i; Till iiJr 'II!!1 "11 r,' 'U,! ,f M' 11; !l, KM, nil pi
ypen limestone channels are relatively simple and inexpensive systems to construct. However,
"' i; Illlllllllliil1 M;)'lii'Jili .,^ h V, !i: J!lITf'' "ii. TCflliliK'i;, i} "' lh|J", Jl11,IL'! H'W,'!i' Elililp i1 ill ii'!'.;i:',,lllllBf 11 VVIlllUliW I : Vf '"'' "I1 Itllj!,!!' !K'i." ,,;:',S '' i1 i1,,I!';lill'iii* 1 ,Ti!i
tnere are some limitations to their use. Neutralization ability of these channels is greatly limited
by the dissolution rate of armored limestpne, atmospheric CO? concentrations, and contact time.
""'Additionally^ the reported dissplutipn rates (Ziemkiewicz and others, 1994; 1996) may be greater
lull! 'BBilBB Jl!"'l;|!l|| I
'^^'ithan^what is cl|ern|cally possible. Acidity reduction of up to 5 percent may occur due the
I
^^^Lisi :. .i:.:':;ifbrmat!on of the minerals swartzmanite and jarosite, which store acidity (H+). Calcium
llM'iBB'BBIBJIB; ill111!1! IMn
I IIV"! :::, !'B I1 BBB BBB ,i,iUi >,:,li:'T! I
-------
Coal Remining BMP Guidance Manual
1999). In order to treat relatively large discharges with considerable acidity concentrations, very
long drains (>3000 feet) with thousands of tons of limestone would be required. Therefore, these
channels may not be applicable to space-limited mine sites. These channels require at least a 10
percent slope to prevent clogging, so they cannot be constructed in areas without the required
topography or where the receiving stream is too near.
Oxic Limestone Drains
An oxic limestone drain, unlike an ALD, is designed to treat water containing appreciable
dissolved oxygen and iron that has been oxidized (ferric). Like ALDs, OLDs are designed to
promote higher limestone dissolution, hence alkalinity production, by concentrating the partial
pressure of CO2 (Pco2). The Pco2 is increased because the drain is covered, hampering its escape.
The limestone dissolves rapidly enough to make the surface an unstable substrate for iron
armoring, because the chemical reactions within the drain cause the dissolution of 2 moles of
CaCO3 for each mole of Fe(OH)3 produced. The iron hydroxide (Fe(OH)3) and aluminum
hydroxide (A1(OH)3) will precipitate to some extent within the drain. However, Cravotta (1998)
observed that some of the metal floes were "loosely bound" and were eventually carried down
through the drain with water velocities 0.33 to 1.31 feet per minute and residence times <3.1
hours (Cravotta and Trahan, 1999). Additionally, the drains can be designed for periodic
flushing to preclude buildup of these metal hydroxides.
There has been limited research on the use of OLDs to treat mine drainage. AMD with a
moderate acidity concentration (< 90 mg/L), a pH of less than 4.0, and moderately low dissolved
metal (iron, manganese, and aluminum) concentrations (1 to 5 mg/L) was treated using an OLDs
(Cravotta, 1998).
The drains studied exhibited decreased iron and aluminum concentrations of up to 95 percent.
Initially (first 6 months), manganese concentrations were unaffected by the drains. After the
initial 6 months, the manganese concentrations were lowered by 50 percent, because of
coprecipitation with the Fe(OH)3 facilitated by higher pH (>5.0) of the water. The higher pH was
Passive Treatment 4-21
-------
'I!,!'!' , "Iliii,1" i|!i ' !!!! 411,, nillnllllh ',,,;!ป V, "11,1
fp,';(^ Coal_Ktmjnmg BMP Guidance Manual
^^ iiiii
lull I', in ii HI iii iillli'illlll! I' I i i iiiiii"1 i ii "i i ii iii liiiiliiiiii" I ii'iii"" lUii ii'ii'i' I'liii'im iiiiiiiii miiiiii 'in
!!!ffS;;|1Sjdue to increased alkalinity production as the water flowed through the drain. The rate of
alkalinity production was greatest initially and decreased as the water traveled through the drain
'""'"""^.""(Cravotta, 1998). This observation was likely caused by the more aggressive nature of the water
ซi* ==iiasi acidity (H*) is released with the formation of Fe(OH)3.
3iln1|lij!iF i "I ''iiiiiJliillllllllElllh II'1,1! :' Illl1 "II!1 Jlili^l^Kiinpililll*^ LFIillllll'lIK III, "IK: 4ii!^/rVII"!liiiii I'l'ii.UIII > V1 JlWi'll1" ' TIP1!, ,!!:':'", :,!i ' ' M1' i,,, ' ' ,,: i T '! EW^J^i'S^ii^r''!!!*, ViL "Jllll1 Bl ,..il!ll"!',"'i., Ifei-1! 'll'liUillili, II" lill'il'W,,!"1 iMIIli"1;11'111 'IViiWi'i!', l^iHIVlllIII1',.:!! llillliliil'lllllFlllllllllilil'lli'illllllllilHIIIIIII!
^J:"; ,!'," ": Djain, sizing criteria are based largely on the discharge rate and desired alkalinity production. The
rate relates to in-drain residence time, which in turn is related to treatment
lllH Ilillllj1 llllll:,},:111! iiliW I "ill illllli"!!1 "lilil 'fii i; !' iii! 'WMlI'lKi:'" livi'i i:1 *',;,:; . llllll' 'iOCtEKf dKJBtRi:' S!3>K KM^, 'iiliiiill< I!',;: IISl! !! !?i' "IV is: .til ' iJll 'III* :li;f llillli I1 lilK!:,' 'SI I
SJfJSfiUyerjgss. Cravotta (1998) recommends that a perforated-pipe under drain be installed to
, , , iipii^lffiMil^Pf 4(fiiM^Mฃ z^w mmmm mm a ^m i> x.Mm s %
periodic flushing of the precipitated metal hydroxides.
l""""""!liiil w"''1"'m' '!iii" >.i|Sg/OtfiougrI the" research and use bl'bLiDs"are'limited' at this" ||mg""|ggse ^'^smay be "a low" cost
IIซI ..... .'. , IILTlie
low-level mine drainage. These drains will likely fail to effectively treat if:
^e'"tob' ...... nigE for the required detention time.
i" i .iiiiiiiii,,:, HDD',, '', in,,, i* ', Mm 1 ne
;'"llliE,ill|,| I'l'UlllMfti'il'!,' IllllUlllllii, Illllil ' AHifi1", Ill:, ,r!lllllllj,|,,'',|,|,!fl^
|i!lJ!l,t''l|K " 'il:!ll(i ': Illl'
'"ll'lll'liln'lllt l",ij
11! . lllllilllB^^^^^^^^^^^ liilll'liltllt I1IIIH':'" . ,1111111 III I III 11 II Illlllllll Illlllllll Illlllllll 111 II Illl Illlllllll I Illl 11
acidity is higher than the limited reaction rates allowed by the drain .
WM^^^ ill1! ..iJl'iill'1 19' Ui'V^^^^ Hill
Illlllllll
iiiiii 111
::!r,;:'' !i:::, .i".''1' E.*"^'."TJie. rneJal.concentratiQns of the inflowing water are well above those previously tested.
Drain clogging cannot be prevented or abated.
The Pco, cannot be maintained at a high level.
j||||||il!!iil':i!i; SU; f lllIllillElliiillliil'ii./l
'
iH|""|i il1 'I'1''1 LI lib,,,,'m
I'll"!! fl"'!*",,!,!!1! .'i
,." 'jiHii'ilBHIiri ii I1!:ill: r ''I'll'1 "K'IFI I*" V
11 'I'l'iHiiiiiiiBiii i,, iiiini'iuii" i' 'I'liff"': '
lifliM^^ i, llg! i1 'I'"""" - '" ' 'ซ' i "' 'i
yrolusiteฎ Process
ii i, , it:r ii n" ii .^ijiiiim,' :;:,i, a n :i,niiiiii m \ : mil. * ,t iiiiiiiiiiiiiiiiiiiiii1 > iiiiiiiiiii,ซ,, miin, 1:11,1' i' iiiiiiiniiP'HiiiB; I,I,BII: i'; i "ijihiป:, n "iiti,' mi '"'i ^ mi.' i. * si i iii IIIIIIKIIHIH < a '>,' jiiaiaaia j" inii"!1" tii1 j:1", diiiiiiana K ai, ilia i naasป."! i11 i i i' ' H i n (! iiu n" n11 Kin i'| ii "i1 lull" ' 111 i > i '> f
,,*,^ .rP^fnune y~a"j.m"~j:1|"|acj|jgeS5 J0 some extent due to the detriment of manganese on the stream
quality, and the best practicable control technology (BPT) of existing water treatment facilities
(Kleinmann and Watzlaf, 1986). However, the toxicity of manganese on aquatic life has not
i 4-22
Passive Treatment
'I" ,l|llil!HI,!,, III NilHIII Will, i!' Till!' |,,,P .!:' rilllll IP": ''HiUlil I"' I;, I,.',,, ill": II: "lll'ii'?'',! ,,. ,,|,! I llllll ,i,,T ,,,,!,![,
-------
Coal Remining BMP Guidance Manual
been conclusively established. An effective and inexpensive passive method to treat manganese
in AMD has been actively pursued for several years.
Vail and Riley (1997) reported on a biologically-driven patented process to remove iron and
especially manganese from mine drainage, while raising the alkalinity of the water. In this
process, a bed of crushed limestone is inoculated with "cultured microorganisms" that oxidize
iron and manganese in the water contacting the bed. These aerobic microorganisms produce
relatively "insoluble metal oxides" while yielding alkalinity by "etching" the limestone hosting
medium. The microorganisms are environmentally safe and are not biologically engineered
(Vail and Riley, 1997). The metal oxides formed during this process are believed to be
manganese dioxide or pyrolusite (MnO2) and hematite (Fe2O3). Both metal oxides are relatively
stable and insoluble in alkaline water.
The system is designed so that the water has a protracted contact with the limestone with a
recommended minimum residence time of 2.5 to 3.0 days. The engineered treatment cell size
should be based on a projected maximum peak flow. The purity of the limestone should be at 87
percent CaCO3 or greater (Vail and Riley, 1997). The hydraulics of the cell should be managed
to maximize water contact with the limestone substrate.
Results from a Pyrolusiteฎ process cell monitored over a 5 year period showed a dramatic
reduction in metals and an increase in the pH. An average influent of 30 mg/L manganese was
reduced to below 0.05 mg/L in the effluent. Inflowing iron ranged from near 1 to over 115
mg/L, while the effluent was consistently below 1 mg/L. The pH of the water was raised over 2
orders of magnitude from about 4.5 to over 7.0. The pH improvement is directly attributable to a
dramatic increase in the alkalinity from about 10 mg/L or less to an average of nearly 80 mg/L
(Vail and Riley, 1997).-
Restrictions on the use of Pyrolusiteฎ cells stem to some extent from the limited knowledge of
these systems and details on precisely how they function. The mineral created may in fact be
todorokite (i.e. delatorreite), which is a more complex manganese oxide (Cravotta, 1999). The
Passive Treatment 4-23
-------
iii... jiii'ii'" i i! Iii >. * > > t & ii:; ili'iii'"' B i'' ..< ?. ii B iiiuiiiii' * iiiB .""''"B i. ' iJii:'iii B . jij,.: ill i i" ||,< ii' BJiilnj'1 i 3 < iii ii :,;ซ :'i i'Bi i .:i iiii:,, ilili.' ^, iiiii < i
liillil
lljBilll'IBBIIIIiBIBBil.BlljiP^JII'!
"** ^^':'"'"''!':i^^^^^^BMP'oS^^ce^imal
BIHBBiBIilBBBBBB1:1 BiBBBIBlJB , BiBBB , Bli; BBBBr "/'JB, ^BillBBBJ' B,,1 vll'l" Si ' I", 'BiyBB ,,,BBBiil,iB I1' iii'i!!' , .IW,.; "';,. Hilli! BBBiBiB
, ,1,'ili,, II l|M'flil!l in, ''illi'KI1' ' III!,.!!""' .."':' "jlSI'B'iiiilli!"1!!1
,
|j 11, ! i ti!' ซl 11,1 '! Il:'; 1 "'"' *' iiliiiBlilBi * i,!!' ป' !
'; ' I ^: nil:? Illjinilllllljl: ,1111,1% ^ :li,' ISII!]! Illlli,11 i"1' ''', IIH: IITllll I,, Illll,
-^at oxidize the rnetals may b"e inherent in nature. Therefore, culturing and
inoculation procedures may not be necessary. There are size considerations in the construction
of these systems due to the relatively long residence times recommended (2.5 to 3.0 days). A
large flow rate would require a fairly large system for successful treatment. It is also uncertain
how highly acidic (pH < 4.0) metal-laden water would affect the treatment process.
Alkalinity-Producing Diversion Wells
IllJIIIi! ...... I!1! ..... Ill1,
( i in in 1 1 1 il
"'i I1 Alkalinity-producing diversion wells a low maintenance method for treating acidic water, were
developed hi Norway and Sweden using a water pressure-driven, fluidized limestone bed. This
technology has been modified for use in treating AMD and streams contaminated by AMD
.............. LJ , ...... ,j inr>i\
(Arnold, 1991).
IB BIBIBBBIB1' : lhป, IBIIIIIn
Typically, these diversion wells are large cylinders (commonly 5 to 6 feet in diameter and 6 to 8
feet high) composed of reinforced concrete or other erosion resistant material (Figure 4.1e). Two
III IPII 11 I II1!)!! IIIIIlM IIIIIIH 111111 i llll ill 11 111 I 111 III I II 11 II I III II i IIIIIIII111 P III III I Hill III HI II lllllLlI1 I I il II "III ill III ill III 111 ill n I 111 ill lllillllil I Hill
manhole sections, one on top of the other, are frequently used. The bottom of the well should be
equally strong and erosion resistant and is commonly formed from reinforced concrete. Water is
i"-:V..=pI)j:Hid into the center of the well with the end of the pipe just above the well bottom (2 to 3
. _ ..... ....... ikilli'^ I
Inches). The outlet point can also be fitted with a metal collar with holes drilled in the sides.
iiiiiiH ijtiiiiii, >'^i:mi. ..... : i ,: i in ...... :ir ....... ' ..... ::- ..... ''::::: ; * ..... ......................... .............. ...... ป, ......... ,i ............ ...... i ., , .......... < ป ,' ,ปi, ........ ,,,.i .................... ;.<, ...... ....... , ..... , ......... i ........... ,,< ...... <- ....................................... .............. .................. ................ > ............ , ...... < ................. , : , ............. > ....................... ป, >>> ..... > ............. > ....... ....... ....... i ..... > ........ ........... . .......... , ....... ........ - ....... , ..... ...... ,>, , ....... ซ, .................... , ........ ^ ............ ...... ............................ , ..... , ......... I
an<^ aPPears to be more efficient than directing the water
.......... , ....... , ........ ,,,,, ,, ..... ....... , ,,, ,, , , , ....... ....... ........ ,,, niiinii, ....... n ..... ..................... ........ ........ .................... ,, ............. ,,, , ,, ............... ,, ............ u ....... ,, ,,,,, ,, ......... ,,, ......... ,,, ...... ,,, ,,, 111 ........... ,, m ..... ,,,, ,,, I, n ui ..... iiniiii ,1.1 ............... u ..... l il ..... i .ป ml ....................... ........ ....... , ....... u ll ....... m ....... in ii,ii ...... ...... ...... iihi. ......... .n, n i ......... n ..... i ...... i M ni il ...... il ............ n ............. ml".
downward. An 8 or 10 inch pipe size is recommended to provide the required flow rate. The
water is fed from a point 'up gradient, where the water is dammed to yield a consistent 8 feet of
tiie we|l surface ^Arnold, 1991). A anying head of 10-12 feet was suggested by
G). Only a portion of the stream flow is diverted, while the rest
"ll!!ll!'" ' iiBiEII I'l'.!",:'" ;i!':,' ii' i, ' 'SI;: '' IB1';]! I!,BBi! !!i' B^B, fiBBiir:; BBili; BBfซ, ',, t ij JiiiBBB!, .B.uBBBB'i iBBNIn,! '" BBillUfiUiBBHV iBBBBBBiBPIBI1' IIBIBBBIII3, , ' I. B1,, '> ill .BBBiBBIBI, iiJIIIHB,..,:, i.''! <, i,,BBI!li !,i
COltinues to flow normally downgradient. The recommended flow rate should average about
w;|p !|^f ? "gpm ...... {Aripiolc!,11 ' 1 99 1J," How ever, ' observations ..... of wp rking wells "in eastern ..... Pennsylvania^ [[[
~~: ~~\- -;' ^indicate ..... that ..... a flowrate ..... of] ..... 12 10^224 gpm may sufficiently operate diversion wells. McClintock
^Tii-and others Qpcm stated that stream flows as low as 100 gpm can be treated with diversion wells.
ll' <:,:!;; liniB!"'1 " ijllllll BIIIIBBUBBB" Jh'1, BIEBl! Ill' BIIBBIIBBBIEliB JIIIIIBiilllfilllllBE !' ', < BBIBBI/!1 ,,,i , ..... n . i, . ,r mi, ......... ....................... ....... , ........ < ........ ........ T< ..... ............................................ ,, ซJAt low-flow streams virtually all of the flow will be routed through the well. Crushed limestone
ItlllllllitJIIIlllllliillllllBlh Bli'i BIB"!'', i||llBlilBIIII ,:,lililll' III "Hill JIHIBIIBIBI?!1 Illilllllllllllllllliill''!!''!!!!'!!!! l;ป' HPIili lil'l' jlnillllllilllnlPi 'Illlltti aillll'npiillll'IH S, Sซ .,
ll'Ilil!'rKillII l^llllihiilJIIIIIiailllllllllllihil ihilli iiiiriJiP''^;.^^^!!!!!!!!!!!!!! IliiildlliilliliUi! lllllllRIIIIi11!"! 9 llliillllliiJillillilKIMnfilli^
ฃ=:=:::= :::?::: "ris dumped into the well. The optimum size of the limestone is one-half to three-quarters of an
fllllil]i!lji!j]!!^ ilBllii!1:' ''I'li!,!'}' 'I;'!' l,8:!lปl!lili!ilT'''i!:iilllllii!::itlll!iiil!ii1i;!!liiii:llll!llilli!:llllllllll!^ :;lJ:''l.l;ilJI!!!i:!g..J!1!!!il"':J!iiin Miiihllllliliiliiiailllliliiii'...';!!!!!!^^'^!!!!!^!!!^^ illlllllillliillllllllll JEi!111'11.' I1'1!' IWI. W^*K t '111 iillllllllllllllliHlg fV8fW
IIIII'M ilUbCMiUVIil!1 IB llll F Blur Bll Ijlllllllllll P'1 BIBB "L :,,'i ,IN,iilllP| ,ป,
'K Ii,: ซ!:,'! :!:iilllli|^ IF".1"' fl. IFiSJ i,1!"
iiBiliiil!l"BiiiiBfl < :W i'!i!uli i1'"'''!'"!!"') vJBi'i .1 BBl
Passive Treatment
iซllllll I"1:]1! i,'i if
ifi'''1 l1:"',!'i1:.iti ' "T:!,,:,.
I" !|H I Hi) ,i,l : Iiii i JPIilllU1,,. ' , IIUI'I R ii'llni'in; II;, jhijiiin i ;,,"" f j:1,' ,:' i ;|'|||| 11: || lull H.
iB BBBBBJ
-------
Coal Remining BMP Guidance Manual
inch. Smaller size particles tend to easily wash out and larger particle sizes require higher flow
rates to maintain a fluidized bed. The rapid upward movement of the water through the well
causes the limestone chips to roil creating a fluidized bed. The top of the well is flared to
accommodate an energy reduction in the upward flow which inhibits limestone from washing
out. The well is maintained to be consistently approximately half full of limestone (Arnold,
1991).
Figure 4.1e: Typical Alkalinity-Producing Diversion Wells
Stream
Dam
] Intake
Crushed Limestone
Modified after Arnold (1991)
The water intake point needs to be constructed to inhibit the uptake of leaves, sticks, and other
debris, which tend to clog the plumbing. Arnold (1991) recommends a tee with each side fitted
with an elbow open toward downstream (Figure 4. If). Air vents drilled into the tee are
recommended to allow the bleeding off of entrained air from vortex action and from air entrained
during low flow periods (Arnold, 1991).
Passive Treatment
4-25
-------
I in mtu mmm tm' i iiiiiw' iiiiiiii'iiii iiiiii PHI liiiitp ill' i r 'i i PIH^
iCoal Remining BMP Guidance Manual
Figure 4.1f: Example of a Water Intake Portion of an Alkalinity-Producing Diversion
Well
I1 ' III i 1(11 1 Hi i "i 11 1 1 II "I 111 Ilillllli i H11 ( in ' li
ipi i inn i ill in i i ซii i iiiiii i ii iiiiii in in i ii i ii
I! 1 If alii;!1!; Hi llWlliJlf < ', ' J ]i ' ''!! ...... I' ilillllL IL :,1 , ..... , ' 1C ' I ,: I!:1!1!1 . "0 j
n I "f':,,::K ir '": lllllii " i ; S,if ]' .iii!1 ' !' I ;:? i ,;,, lil.Ulll
1
Stream Flow
'.' i' i Air Vents
-y x
' ' '
i -' '
1
ifSfi:;:":S'"S"'':: 11:11;'!!!!!'!1' i^Jli
I1!-:!' ,,4lih I iilinnniliiiliil'qi'VJl'iiill'ir' jjlir1! ,' ',,!'
i!1 liig )
Intake
To Well
Modified after Arnold (1991).
i!! i iiiinrn1 ...... l
jilK i:;
ih <> ...... ' iiiiw "i:i '< ...... ^iMfi
III'lllllllIT'}, sllllll'liVJilr nijl liui I', il.niii l|l|W"i M'lll , "I!1: ',i,||'l!Lvซf 'I |a,||| 'i|,' rrii, fiiy'i,; "HI!""!'"
:ijj!jljjjjjjjjj I, flBiriil :ffV>- iSl'i- -*"-' V *!!!"'-IB' :ซซ!ป "I"1!' V 'i"
i,;Iiiiii;;fHSCW'ifcHtilli iilli" '"> i ii-' it'ซHr1'1 ,,ii U,'S'~;>'ill,Mil: j
' '1 1 .Mi'nili1 ' "iliiH1 Iii E LAI Ill
n1 'IIPI'" ID1 ..... IIIHTH ilซl '' ''Hul'illlinill ......... IIW" 'i \! I : "' * ' " '
' ; ''-ill! ...... ;1JfJrf)fJ*H ...... "I*!' ' ' ...... ' '
tii'iii'l.iii: Jilf PllS ..... ซ;, i iJliSiiiiSi.!, ..... iiliili1: ', ;i -'.lit '; ..... I'll :
...... '< i ; , nil I 'I1 il :M i :. I {' 'l
i .S,t li lii: iiJiilii
^ilS111'-'!'!!
I
wells yield alkalinity from acidic water that reacts directly with the limestone and by the
*1f!! ..... *!"", "bHumins ..... action ..... bT'ffie"fluidlzed ^g^'g^gj^g ^g1 limestone into fine particles. The finer
|| IIIHIIIIIi:, Illr Jiiiiliif iiliii'illlliillllllii.i '' I'l'i'l] lllllii ill1 1'.iiiill ll'IIVi'lllli'lillP"!!".?^! [[[ TT ............................................... i*nr [[[ * ..................
w-ter n ^e w S additional alkalinity and
!:|ป!niH^^^^^^
are earned put of the well and_ to the stream to react with the remaining acidic water that is not
piped through the well. The constant churning and surface abrasion of the limestone prevents
^'^^CEPQQng by dissolved iron in the mine drainage. Limestone consumption rates vary with flow
\ ; ; : I
rate, well size, Jimesfone purity and hardness, and to a lesser extent water quality. However,
I i| "I1'1'" 1|K ill) JIIIIIH^ !i lllllllliliHIilllll1! ii 111 i In ill "i
., t=,|nese wellg are generally designed to use approximately 0.92 yd of limestone per week. Purer
., because_highly dolomitic, very hard limestones tend to react too
. ' , liH^^^^^
.old, 1991). It is important to note limestones that are too soft will break up too
:" :
I ^sity* rapidly wash out of the well, and require more frequent replenishment.
: ' !
I iii:iIsiid,iiiii *":'; i JiiB^^^^^^^^^^^^^^^ ' iiiiiiM'"iiiiii'iifi'Iiiiiiw ii::>l: iii' 1 i:iii; ::ii:iw i/iiri^i-^I' Iwi;/:1MK^JWRndiRIS ;>":iislx^f.:IK i ilii-
. I
llll'l f ll'iil I
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1-26
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Coal Remining BMP Guidance Manual
The turbulent action within the wells preclude in-situ iron deposition. Any dissolved iron
present, above 0.3 mg/L, will likely precipitate after leaving the well. It may be prudent to have a
settling pond constructed between the well and the receiving stream to collect much of the
precipitating iron and other metals.
Arnold (1991) recorded an increase of one to two pH units (orders of magnitude) of the water
leaving the diversion well at 5 cfs. McClintock and others reported a pH increase of up to 3
orders of magnitude. Arnold anticipated a rise in alkalinity proportional to the pH increase, and
which alkalinity was increased somewhat, but the concentrations remained relatively low. No
detrimental impacts on the in-stream aquatic life were noted with the use of diversion wells
(Arnold, 1991). The limited alkalinity production is due primarily to the low (atmospheric)
levels of CO2, which govern the rate of limestone dissolution. Watten and Schwartz (1996)
proposed pretreating the mine water by injecting CO, under pressure (100 psi), which increases
CO2 saturation by 22,000 fold. This CO2 saturation increases the potential alkalinity production
to 1,000 mg/L (Watten and Schwartz, 1996). However, CO2 injection is not passive in nature and
would dramatically increase the cost and labor of the operation.
There are some restrictions in the use of diversion wells. These include, but are not limited to:
Sufficient grade is required to maintain the 8 to 12 feet of head.
Sufficient flow is required to keep the well functioning properly.
Waters with high acidity concentrations will not be completely treated by one pass
through a well. The water may need to be piped through a battery of wells to achieve
complete neutralization.
There is more maintenance required for these wells than is needed for other passive
treatment systems. Recharging of the limestone may need to be performed on a weekly
basis.
If considerable dissolved iron is present, an additional settling pond may be required.
Intake clogging may be a problem during certain times of the year. Keeping the intake
clear and unclogging of the entire piping system are periodic maintenance requirements.
Passive Treatment
4-27
-------
Illi"*11';11 M\ 9l>l'i|i!U
J5S\JKฃ, 'si; ;;;,; :\:;' ^ฃssLM,ฃ!2!SMiS. ^MP Guidance Manual
lill ililillni' :,F:,lilPllih ,?' ," , :|
liWTO.fi j?iifc, ' illllllllliiiiir!: ill V
_
" Criteria
'! M,b# PitS'C'i 'rWli M t'" F; : t." J!:11,,,, "1 Ti'"!:* ILr !L| 'lf ;]ihii Wif;' H-! liU1!!:'," ,i r i'1!,'WW i,:!"' WlWr ' 'fl-i'WEtt
'"I"! ,,;,i , 1R^
i/i'i'"'), : i' 7 IT : "'. -a M:,S\FI '!>'i vii iiniiiiiiii iy' "i fliiii iiii *;: ^i! 'ini i* '"[:! liii'i'yiiiiliiii'i1 iiiiiiiiiinmiliiii '"wnit Iji iJiii' iiiiiiiiiiiiiiiiiiiiiiiiiLiiininf' ', 1'!' J. iiiiiiiiiiliii,' .11117: i niiiihjiiiiiiiiiiiiiiiiiii \ iii liiiiii; "
EM5intenance once constructed. These systems are engineered to raise the alkalinity and pH while
facilitating the precipitation of metals. The mechanisms of AMD treatment rely on metals
oxidation or reduction and the production of alkalinity by sulfate reduction or limestone
;;:,,;,,:;,,,;,,,::: ::;:::;;,,::,,:;, :|: dissolution. ^The^design of these treatment systems varies according to the type, but there are I
^asi|c' requirements that are common to all. The following list includes basic criteria of
'/M IB BiiM^flHliiaii^'^'riii'-^; sn f-y^i r^ WJ^!1ilfe'iiJiiป!'fi*'JfflV(!fft!*ซ^^^ itiiKM Ill
passive treatment systems:
,ii.NihiiiiiilliJ<"lH';!!:: IP I'll1,:!!' <
III ' ',]!,'if " r dl'llltFI 'ijp'l "IJJVt'r; l| ^Ipplpl1 '!'
pata. are required to determine anticipated flow rates and water quality.
# "r^The size of the facility is based to a large extent on flow rates and detention time.
The type of system to be employed is directly dependent on water quality (e.g., pH,
ferrous vs ferric iron, dissolved oxygen content, net alkalinity, etc.).
IE-!ft ;,i;' ;L^l<'J!Ti3Cllฃ Pon"est CaCO3 purity limestone is recommended.
r!" wn. i;" IS!1'1,; yj'^Cpifsiderable'^ais gelaerally required to construct these systems.
lift, i 'ii: I,, ';i;,,:' il'11- ,'K ? '.WBf CWKTIB' 'f!"I $'$lK!Wi8iป!iBtti::, in. ii,K,iป-:: v:ซ' ซ:iป *. v.t " a,
is required to permit gravity-driven water flow through.these systems.
llMfci^rtHfi^S'^^^iiiMi!
3se systems needs to be
efficacy to be compromised.
"iijffit :, ::,! ,', IK: f- ,! :'fflt iJl. ii'iiH^^ iiiiH .XliiSl ailii I'lieiF j> lit, ;,>-: tfttiiiitlL'Ui; iii1' t,.J ; ,!4! fill.!'!1 IUJL'flni:HnHVrH :'::!!' af'' ,f!;,;, SI!'", 1C' iii t "t? I Ii! !' ll,Si:,'!i!,il': iilill: 'SlsiX! -Ilia n !'!,!<'' J,:,!!]!- 'll!i!)!;' lil'3 PI,! : i'iii,-!"],, I11!;; Hi, 'iฅ!,,,,::Ki it i ii 'if, 1, ii', ,i (i -:' I, ซt'Stiif :.iiii,:,i,:;i:, iliJ'liill,: ': .? '^ihiiiiiiniiiii i, t iiiiiiiiiPiiiiiiiiiiip;,,i:iii:iiiiiiiiiiiiiiiiiiii '"win iiiiiii::i;'i' iiiiiiiiiniiiin pii" A \::SK\P M niiHii, i" '>n us > mi"f ;i; v11 ui: I'laimii1 IIIPI in "iiiiiiiine1,1'. "'Jiniiiii!1:1'" i,;;; <" ซii I
remediation of the discharge pollution loadings. Monitoring of the water quality and quantity
iii:Ihijimliiilijllilli! i'iiiiiii1 Tiiimiii,1!' iii!i,ii'',, ,ij|iiiiiiiii'iiiiii i""iiinviiiiiiiiiiiiiiiiiniiiiiiiiiiiiiiiiiiniPi'ii:iปiiiiiiiiiiiiiiiiiiiini":,:ii{j/piiiiii'iiiiiiiiiiiiuiiiiiniiiifiipiijiiiniiiiniiiii rump,M *ป S, S, ,,;,J ฃ ^ , r |
will be the truest measure of the effectiveness of these gjy[ps j^e impOrtance of field
i; ; , ,
ซ ........ 1 ..... 4-28
Passive Treatment
I ..... is&tm.
'
i ป*
'* "" ::: j
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Coal Remining BMP Guidance Manual
verification of all aspects of a BMP cannot be overstated. It is the role of the inspection staff to
enforce the provisions outlined in the permit. The inspector generally does not need to be present
at all times to assess the implementation of the BMPs in this chapter. However, during
installation, some passive BMPs will require closer and more frequent field reviews than others.
The truest test of the success of passive treatment is the water quality of the effluent compared to
the influent. This assessment is determined through sampling and analysis of the water and
measurement of the flow rate. A sampling and measurement port is needed to access the
discharge prior to treatment. An assessment of influent verses effluent flow rates is also
necessary. Greater outflow than inflow is indicative that the system is gaining unaccounted-for
water within the system. If the outflow is less than the inflow, the system is likely leaking. If the
treatment system is gaining or losing unaccounted-for water, it should be repaired. Topographic
maps or surveying can be used to determine if sufficient grade exists to adequately drive the flow
of these systems.
Implementation Checklist
There are several items that should be monitored to ensure these treatment systems are
adequately engineered and installed. This list includes but is not limited to:
Measurement of flow rate and analysis of the water quality of the discharge. Treatment
system engineering is based on these data. Water should be especially analyzed for DO,
ferrous and ferric iron, acidity, pH, alkalinity, dissolved aluminum, and dissolved
manganese.
Measurement of the flow rate and analysis of the water quality of the system effluent.
Compare effluent quality to raw water for efficiency determinations.
Monitor the amounts, size, and purity of any limestone used. Limestone purity should be
determined from laboratory analysis. Monitor the type and amount of organic materials.
The amount of limestone can be determined from reviewing the weigh slips or estimated
from the stockpile dimensions.
Passive Treatment
4-29
-------
i:';;Ji;^ I
> em i'f s ' . !; ;!"'*,,
; ...... ' ............. ' ....... "*- ....................... ; ' ..... 'ft'" '' j ...... TCoal Remining BMP Guidance Manual
Pll'llCLiidi ' ' liiiJIlPT'lBlllUnnii Iflll" lllinBRIlH ...... ..... "A, '' ,,, *; r "!ป iui,:: iiiiii!" nn^y'ismi^MK iซii& ซ'' ru f" ',;:i
of the verification techniques are common to several passive treatment types, while others
Kfi I
,;,;, ,;.; .- ;::,;, ;, , .i ma^be system-specific. The following list include implementation verification techniques for
jii'iiiifj*: i) 13 - > 'ixck-KJ' m;ป<>."
................... , ......................... .. ....... ...... ............ , , H ...
;: i ~ i ;:. ii :a i<;t ...... :;iil KT- i ...... m, "f, ; :>- >
treatment systems:
'' "1 1
'1 *i,!i;:w" ........ fle,1. wiW' s li/'r^i! '"'iiiwii!] p iiiiiiiiiinniin iniiiiiiinni
ii ,i ; it ,111 1 ; : "m ,i :i r " ' . ...... "ซ: ;; . "j,', * t, m:\ ...... ii, . ; i y, \ n i1, m\ \ in i n iiii i n iiiiiiiini n i
ป The size of the trench can be measured during excavation for comparison to the
4B o r-
calculated amount of crushed limestone required for treatment. A cubic yard of crushed
i
limestone (1.5 to ..... 2.0 ...... inch)_weighs about 2,300 pounds (Nichols, 1976).
Coyer material (e.g., plastic and clays) can be inspected prior to use or can be viewed
during installation. If there is a concern as to the adequacy of this material, certification of
the strength, permeability, and other properties can be required.
The DO ...... and/or.iron ...... oxidation state ..... ofthe,effluent ...... canbe ...... analyzed to ascertain the ability
ill III 1 11 I IIIIIIH i3li
of the drain to preclude atmospheric oxygen.
A lagk of drain outflow and/or the existence of unanticipated discharge points are
indicative that the drain is clogged and/or cannot handle the amount of water piped into it.
Drains should be sized to permit at least a 15 hour, preferably 23 hour, detention time.
Constructed Wetlands
Sizing of wetlands can be directly measured and compared to the flow rate to determine if
they were sized adequately to properly treat the water. It is recommended to use a sizing
factor of 10 gdm for water with a pH of greater than 4.0 and 4 gdm if the pH is less than
[[[ [[[ ........ [[[ .......................................... | ...... [[[ | [[[ ............................... ;
(He_din and Nairn, 1990). However, a sizing factor of 15 gdrn may provide reasonable
^ ii;;!; "_. 'ii A iซ I ' it AJ j' >;i ''U ;' f'i1!' liiv f iijiK ....... piiiip^^^^^^^^^ 1|:i 4, aii:: i! >: ; :';i" ",'s 1 1
;Blts (Kepler, 1990).
jllll , !' i "j; 7. j JS:, f, , ; ' IR H w# ;, >m,;; ,,,, ป ปm f>.: w* -K-. ; m > ;K S;' m\, 'tiiifS; If":" X,,; 'SSMBW IS!!!: '-ซ! P; E: > "f]-';. S : i:]!';
.'.M.I^'iitfflfMW ('': !i'ซ! Il'.Ki.V'.Kii,,
-:',;:ป!":,;! rtiilfiiiiil! MftTl'jr: i, siSili;-"'!'i:
t'11'0'l
':ซ! P;!!;:-",!!!;:: S :>S'Sltl
^:i'f,":i '''liiiii'llH
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Coat Remining BMP Guidance Manual
the optimal flow through the wetland can be determined from visual observation or by
use of tracing dyes . '
Lack of vegetation may be an indication that the water level is too high or too low.
SAPS
The size of the system can be measured during excavation for comparison to the
calculated amount of crushed limestone required for treatment.
Sizing of SAPS can be directly measured and compared to the flow rate, (using the above
referenced sizing criteria) to determine if it is adequate for proper treatment.
Effluent water quality can be monitored to determine if the iron is being reduced and the
DO is being removed.
The water level should be monitored to ensure that the SAPS will not be dewatered or
overflow. Either situation will impede the effectiveness of the system.
SAPS should be sized to permit a detention time similar to ALDs (15 to 23 hours).
Open Limestone Channels
The size of the trench can be measured during excavation and compared to the calculated
amount of crushed limestone required for treatment.
Sizing of channels can be directly measured and compared to the flow, using the above
referenced sizing criteria, to determine if it is adequate for proper treatment.
Visual inspection or inadequate flow rate will indicate if the metal floe is clogging the
pore spaces in the limestone.
Flow-through rate and average detention time can be determined by use of dye tracing.
Recommended detention time is at least 3 hours to effect 100 percent acidity
neutralization.
Oxic Limestone Drains
The size of the trench can be measured during excavation and compared to the calculated
amount of crushed limestone required for treatment.
Passive Treatment
4-31
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Guidance Manual
II"H!;!,!' HIKi: ; 'H'1'!*1',, XI '', ;<;, ' I; ,i, III ii,:" I' ICC!!" \SVPF V' i " ,1 T: '!! i i'" i!ii,, V'!!';;:, It';. ''IBIIIIHi.iilii"1 Iff HKIIS "i HIHI" i "'Hill .IIIIR"!'!! Jiii1' I , "N il!!i ' .an' In' II I1! I'llWin EHl" liP '' '"'i ..ii'll'IHIIH'I '"I ฃ9, t',ป'
i',,!1'! lliniPIHillillill:11 IIP'II"'.'' .'llli1 I
' sizing of" drains can ke directly measured and compared to the flow, using the
sizing criteria, to determine if if is adequate for proper treatment.
I ...... HEW; ...... HW9W* ........... liซ^^^^^ ...... pfti.1 ...... IDRfflltlllli^^ ...... R ..... ซ^^^^^^^^^^
' lil^'i ..... '"tr! ..... iw& ..... l2ฃJSi,Sฃ,2Hlll2w,.,,iid/oI Hn^SlฃJPated Discharge points are indicative that the drain is
:;L::;::::f ..... :",: ". S "ii ....... i!i;;l=cogged and/or cannot handle the amount of water piped into it.
Ifr*?!Si^;:":!:'ilSr. ..... ^!!rKซ^IiHl.ฃSSi(!ence..tLme.ง.ef ^3 J hours and, water velocities ...... of ,0,33 to 1.31 feet per minute
^Ifll [|S.v Bf jj^||i'S^:i^!?9S^e to effect treatment and flush out the metal floes.
IHit E 1111 ..Slili llllili,
, iiM^ n
i i wi: ? ป .
1 I i
.Hgw^fhrough rate '"and '"average detention" time can be' determined by use of dye tracing.
''"""'" '" "' i The Pvrolusiteฎ Process
i3^
'. I-" iiiiiii i" naiii iiiii'iiiiiiKii
^^ /J^'l'.llllilll!111'1]! i!" illB.i
||int of.crusnedJumestone required for treatment.
, , . . 'iiiiK^
, ***: ^fts^-...':; ; Sizing of beds can be directly measured and compared to the flow, using the above
illH^ .'Hi'W liCiiB^ iSiii1!:!' iiiiiii'iiiiiiiiih'M^^^^^^^^ iii'iiM^^^^^^^ aiiiiiiiii'' (; iiiH^^^^^^^ in n ii IUPMIMU iiiiiiriH^^^^^^^
referenced sizing criteria, to determine if it is adequate for proper treatment.
IIH^ 'lip
;,ซ;Z!!I ซZ :^'!,;?ฃi!^;i -, A minimum detention time of 2.5 to 3.0 days is .recommended.
'ปrซH ll;!|,:ii
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I
^^^^^ ...... i iiiiiiii, i ....... ซE,H:II','I ,: vMttt '-.mtf, .if-ii j'', 'ifi,: ii.i'i"':' :::!' -if mm ....... ,1 ..... 'iitti i/Lii. : ....... \>, i ,k , ...... iiii!" i ................. .i'vi'iiiiiMi ..... ;xm ...... ir:!: i: ....... 1,1111 ...... i'-i ....... i ....... i ........ i: lit i > ......... iiiiiiK^ f n ...... :i 11:1
liiiiiiiGii ..... inni
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Coal Remining BMP Guidance Manual
coal removal. This was a conventional SMCRA permit, for non Rahall-type remining, and
accessed the Coal Creek coal seam. Passive treatment was used effectively to treat the post-
mining effluent. Problems arose at this site when operations were ceased, due to a fatal fly rock
incident from blasting of the overburden. After approximately 80 percent of the mining had been
completed, the operation was ceased and never reactivated. The performance bonds were
eventually forfeited and a mine drainage problem developed from flooding of the pit, lack of
proper handling of acid-forming materials, no contemporaneous reclamation, and other
undesirable conditions.
In order to remediate the problem, the Tennessee Valley Authority (TVA), owner of the mineral
rights, undertook the task of reclaiming the site and installed a series of passive treatment
systems to treat the water. They elected to install an ALD followed by staged aerobic wetlands.
An underdrain was installed across the pit floor as part of the mining process. The outflow of the
underdrain was intercepted and an ALD was tied into it. The ALD was designed for a 30 year
lifespan with almost 3,200 tons of limestone used. Prior to entering the drain, the discharge was
slightly net alkaline (-50 mg/L), with around 40 mg/L dissolved ferrous iron, and an expected
flow estimated at 160 gpm. The drain was designed to yield 250 mg/L alkalinity.
The discharge of the ALD was piped to the staged wetlands. The wetlands were designed to
remove 20 gdm of iron and 0.5 gdm of manganese. Based on these removal rates, the wetlands
were sized at 3.45 acres. Initially, the ALD effluent was piped to an oxidation pond to permit
primary treatment (abiotic oxidation of metals, hydrolysis, and subsequent precipitation) and to
prolong the effective life of the wetland. The pond was 0.77 acres with a detention time of about
24 hours. Following the pond, the mine water flowed into a 2.7 acre wetland. The wetland was
divided into five cells with different water levels and vegetation. The first cell had an average of
3 feet of water and was planted with rice cutgrass, wool grass, and arrowhead. The area of the
first cell was 1.02 acres. The second cell had an average of 18 inches of water over 0.59 acres
and was planted with cattail, rice cutgrass, and bulrush. The third cell was 0.44 acres with an
average water depth of 8 inches and was planted with wool grass, arrowhead, and burreed. The
Passive Treatment 4.33
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Coal R&mining BMP Guidance Manual
fourth cell was 0.35 acres with an average of 10 inches of water and planted with wool grass,
I ''.,'"
arrowhead bulrush, burreed, and sedge. The last cell was 0.3 acres with an average depth of 12
in i i in in in i HIT i " TIII in iiiiriiiiini iiiiiiiiiiiirHiT in"""" in "" in in i"'in iinr n r " -'i inn in i inn in n mini INI inn in n in i i din linn i mi nniiiiinn i iiniiiini iiiii'iiiiiiiiinniiifriiiiiiiini
inches of water and was planted with cattails. Following the last wetland cell, the water was
,:, . ;, ;; ,, , ,.: ; cJ2gฃffii^d to an, existing basin for final polishing prior to discharging.
ll ii, |i ipijiLi1 ,''1111111 liii l;ii; !":,!' ^iiillllliLrnilllFflli ' f ,,'ปi,i 'i' g Jf ..'M, ,!';;':,] lay,., in;!"!')
HIM, '!![, H':!::! ml, ]'
ll'l',ii,',iri'i'",, 'ill I!'1:" I1!1! "I Jl'iiil'ji'iiliiil
ilii'The water of the underdrain discharge prior to the ALD installation (given by the TV A) had a pH
,:,i;iiiซ^^^^ iii'iiif' ''nils <, iiiii Baiiii''ปiiiiiiixipriiii IIIIIH ! '!! 111 iiiiiiiu ii'i , ,>:i,iiiiiiiii,iiB^ n , e ii,],"1:!! Hi '91,.: tifi!'" in, i, > .iaiM<,it,r i > iiiii '!,,iu IIL,''ซin^^^ -: ia(,,ra^^^ /itliiiiaiiiiiiijป, i .'''''li''!!'!!,*!':):'1,:', ::T' ' ti 11 '-j'':!'!!!!'*^^^^^^^^^^^^^
iiiM iiH,;:iปDf 6.0ป 40 mg/L iron, 7 mg/L manganese, 15 mg/L acidity, and 65 mg/L alkalinity. The flow was
-i|i;_ T-giyeri as 160 ggm. These values were used for treatment system design criteria. Once the
'~, ^SsSivQ^ymmwM installed, the raw discharge water could no longer be sampled. fable 4.3a. is
: :; -^ surnrnary of the water Duality at various points asi it flows through tlie treatment system from
.......j November 1996 through August 1998.
i:K
,! f1:ซ Table 4.3:
iM I'lllllIM^^^^^^^^^^^^
Summary of Water Quality Data at Various Points A
JIIIIH i, , ;- , ,, ;,n , J , ,,:, , i, , , , i, ,,. ป i,
"Treatment System
ing a Passive
i<^ SiffS :i*
;i ;:, >.i ''"I?! .tiiiili: > w iซi?:i!3 iv'i ...... '. '
smttm !'!' I
lllllli (ill fill'l
Sample Point
ALD Effluent
Fourth Wetland
Effluent
Last Settling Pond
Effluent
Median Flow
(gpm)
186.5
197.5
197.0
Median pH
(Standard
Units)
6.2
6.9
7.0 .
Median
Alkalinity
Concentration
(mg/L)
196
106
100
Median Iron
Concentration
(mg/L) -
59.50
0.88
0.82
Median
Manganese
Concentration
(mg/L)
24.8
22.6
11.1
iiiiiii ii 11 nil 11 ill in
It appears that initial flow estimates used in sizing the system were too low. The median flow
through the system was about 23 percent above the pre-installation estimate. However, the
iiiiiii iiiii in
IB
iiiiiii 111 inn ii
system has effectively raised the alkalinity. The alkalinity after the ALD is over three times
lllllllll II I I I 111 111 IIIIIII I lllllllll IN IIIIIIIIIIII II IIIIIIIIIIII IIIIIIIIIIII I I ill I III I III I 111 IIIIIIIIIIII lllllllll IIIIIII IIIIIII lllllllll IIIIIII III IIIIIII IIIIIIIIIIII IIIIIII I I IIIIIIIIIIII II I
gre'aier than the underdrain inflow value. The alkalinity is lowered as the water flows through
IB
^ ~ (iiiiiiiii _
i i Hi") in i ill *
in i
liii ii en i n
iliill Ii'I I'III 'IhlllH I IN11 illNIll IIII ill HI I PI
the wetland by release of mineral acidity as iron and manganese are oxidized and hydrolyze. The
final effluent alkalinity remains over 50 percent above the levels exhibited by the underdrain.
"lllli
rli"i|iiiiiiiiiii:iiliiiiiii|ii!liii1|11 f HAH ฃ'HIII
The final pH (~7.0) is significantly above the pH of the ALD influent (-6.0). Ironconcentrations
lllllllll 111 111 (I I IIIIIII II 111 III I lllllllll 111 llllri II IIIIIIIIIIII I III 111 II III 1 II I I I III II I lllllllll lllllllll II 1 lllllllll I Mill 111 lllllli III lllllllll II III III I I
are dramatically reduced from near 60 mg/L to well below BAT effluent standards (
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Coal Remining BMP Guidance Manual
Manganese is reduced by greater than 50 percent, but continues to be well above effluent
standards. The continued manganese problem may be due to the apparent undersizing of the
system. It is uncertain how the 160 gpm was determined for the discharge prior to sizing the
treatment system. Analysis of the existing data indicates that the median flow prior to
installation of the treatment system was nearly 190 gpm.
4.4 Discussion
The remining Best Management Practice discussed in this section relates to improvement of
effluent by end-of-the-pipe treatment of mine water. Because these systems can be considered as
treatment of mine water, they may not necessarily be categorized as true BMPs. There are
exceptions where a passive treatment technology or system may qualify as an integral BMP. If
an ALD is incorporated within the backfill as a pit floor drain, it can be considered a traditional
BMP. If a passive treatment system is installed to treat a discharge that is adjacent to the
remining operation and outside of the permit boundary, but is not hydrologically connected to the
operation, this also could be considered a BMP. In other words, the operator installs passive
treatment on an adjacent discharge, not legally associated with the remining site, to improve the
overall watershed water quality.
Benefits
Low maintenance method to reduce the pollution load of mine water.
Means of gaining additional water quality improvement on and above what is capable
with traditional BMPs.
Some systems are capable of yielding very high amounts of alkalinity and thus, additional
buffering capacity, by maintaining elevated CO2 concentrations.
Limitations
Generally require a substantial construction area for moderate to high-flow discharges.
Require topography that provides sufficient gradient for gravimetric flow.
Passive Treatment
4-35
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II I III I II 111 111 II
II
I 111 Illllll I 11 111 111
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illllll iiii; .(ijj , i QgsiSSSliSlsg^ BMP Guidance_ Manual^
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eriodically for cleaning out or replenishment of the reactive
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"systems !o fail or to perform below peak efficiency.
Metals removal and alkalinity are limited by detention times and chemical reaction rates.
Efficiency
iliB
y i few ofcompleteS remining sites in Pennsylyania (Appendix B: PA Remining Site Study, I
>5 utilized passive treatment as an integral part of their BMP plan. In this study, 2 out of a
j'SiijI; jjiijiiiiijjij;!;: ,i,ijiijp||||||jjii;i;;;i;' 'lijllljjnr'iiijiil^ 3< wp^^ ! ii'111* ft'!1'1' fl1*11,1 ll't^Hiifii!!111' '"/'I ?Jjt,ปJ;:ปiilliil11" ;t,;v H'f if"' i!:i:'l!!' -' "ill:!!!"
"of 231 discharges" were "effected by passive treatment BMPs" However, only one discharge
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treatment BMP for a manganese problem. A statistical evaluation of
iijiif IJK
is notpowerful, because of the extremely limited data. However, no discharge
S'iS" ...... iir ..... iif i .liexhibitgj significantly degraded wafer
fOT acidity, iron, manganese, or aluminum
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loadings. One discharge was significantly improved for acidity, iron, manganese, and aluminum
loadings. The other discharge was unchanged for acidity, iron, and aluminum loadings.
!ฃIU ^ !K^^^^^ iK I
iii'.i!;-i,BSPs in improving effluent pollution loads. However, the research into passive treatment
,i '.piiniiiiriTiiiJii;! illinium i niiJiiiUiiiii
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it Jechiiology, although not generally a traditional BMP, can be used to augment
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ution load reduction achieved by implementation of true BMPs. Passive treatment provides
low cost and minimum labor methods to treat AMD for acidity and certain metals. Research into
I - Igassiye treatment illustrates that a variety o|systems can be used to treat a broad range in water
/. The type of systems to be employed should be tailored specifically to the mine water
I
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-------
Coal Remining BMP Guidance Manual
References
Arnold, D.E., 1991. Diversion Wells - A Low-Cost Approach to Treatment of Acid Mine
Drainage, In the Proceedings of the 12th West Virginia Surface Mine Drainage Task Force
Symposium, Morgantown, WV.
Brodie, G.A., 1990. Treatment of Acid Drainage Using Constructed Wetlands Experiences of the
Tennessee Valley Authority, In the Proceedings of the 1990 Mining and Reclamation Conference
and Exhibition, Charleston, WV, pp. 77-83.
Brodie, G.A., C.R. Britt, T.M. Tomaszewski, and H.N. Taylor, 1991. Use of Passive Anoxic
Limestone Drains to Enhance Performance of Acid Drainage Treatment Wetlands, In the
Proceedings of the 1991 National Meeting of the American Society for Surface Mining and
Reclamation, Durango, CO, pp. 211-228.
Brodie, G.A., D.A. Hammer, and D.A. Tomljanovich, 1988a. Constructed Wetlands for Acid
Drainage Control in the Tennessee Valley, U.S. Bureau of Mines Information Circular, IC9183
pp. 325-331.
Brodie, G.A., D.A. Hammer, and D.A. Tomljanovich, 1988b. An Evaluation of Substrate Types
in Constructed Wetlands Acid Drainage Treatment Systems, U.S. Bureau of Mines Information
Circular, IC9183, pp. 389-398.
Cravotta, C.A., personal communication with Jay Hawkins, 1999. Details available from the
U.S. Environmental Protection Agency Sample Control Center, operated by DynCorp I&ET,
6101 Stevenson Avenue, Alexandria, VA, 22304.
Cravotta, C.A., 1998. Oxic Limestone Drains for Treatment of Dilute, Acidic Mine Drainage.
Proceedings of the 19th West Virginia Surface Mine Drainage Task Force Symposium,
Morgantown, WV.
Cravotta, C.A. and M.K. Trahan, 1999. Limestone Drains to Increase pH and Remove Dissolved
Metals from Acidic Mine Drainage, Applied Geochemistry, vol. 14, pp. 581-606.
Hedin, R.S. and R.W. Nairn, 1990. Sizing and Performance of Constructed Wetland: Case
Studies, In the Proceedings of the 1990 Mining and Reclamation Conference and Exhibition,
Charleston, WV, pp. 385-392.
Hedin, R.S. and G.R. Watzlaf, 1994. The Effects of Anoxic Limestone Drains on Mine Water
Chemistry, Proceedings of the International Land Reclamation and Mine Drainage Conference
and the Third International Conference on the Abatement of Acidic Drainage, Volume 1,
Pittsburgh, PA, pp. 185-194.
Passive Treatment
4-37
-------
i::::. I"! ! "IE
rlniiH^^ s,;,!':? n,* iiiiii^^^ lii'
iiin
- ili' i :li' I i ,3;ii!"ifซ ? t! i; vi Ki; ?!*' .;, -t stf i ; I :. 'ซ*: I Sit iM 'ft: J, K';:' i v ':^\.:- If; i liM" > t Ji I'.' tiifi^ 1; i ii :, :
iiiiniK',;!ป!UK,; nil! ."'ii'riini!,:!,: "VJ" ป> '" ,!*:: .' ' jiV'.r ' ' .-''iS !/.', n |J H'1' wi.*.:"1*;:,, I'-'i:, i" /iiiiiiyiii'''!^ / ' it": is uiiii'i:;;!!11:.' :>!:<., i. r" ..;! JPFV if I1.:!:11!!,!' Ji {
CoglJRemining BMP Guidance Manual
Hem, J.D. t1989. Study and Interpretation of Chemical Characteristics of Natural Water, Third
Edition, U.S. Geological Survey, Water-Supply Paper 2254, 263 p.
iiiiiiiiii i HI n i i n n i in iiiiiiiiiiiii i n i i n in mi mi in mi i in n i i n in i i n i i i in in n HI in mi inn in i in i n in i i n 11 i i inn n iniinniin nn in HI in
illllli i in nn i in ii i n innnninn in iniiinnnnni nun i in i nn mini in i mini n 11 n i i i in nn in mi i i n n n inn n in i n nn i i inn i nun i i I i in nn mini in i i nun i nn inn in
11 Kepler, D.A., 1990. Wetland Sizing, Design, and Treatment Effectiveness for Coal Mine
Drainage, fa the Proceedings ofthe 1990 Mining and Reclamation Conference and Exhibition,
Charleston, WV,""ppT 403:408.
illllli11
ill
'nil'{"I!
if! I
_ ..... !J ..... , ..... Ili'lil!!' 1 ...... Illllllllllllllllll ....... , ..... i!:I!!:ii:i!S^l!!::Ji:r ........... SMWUfclM I ' ......... , . ...... B! ..... filllB^^^^^ ...... ..... , > *, ..... iiซ^^^^^^ ...... I
||i Kepler, D.A. and E.G. McCleary, 1994. Successive Alkalinity-Producing Systems (SAPS) for the
__. __ ...... Mine"Drain'age!. ' Proceeding^ ...... ofthe Siterna'Son
" Drainage ..... ConFerence ...... and ...... the Tnlr^'KtemaHonal'C'onlefence ..... 6rii" the Abatement ...... of Acidic
i".j"(ฃDrainage, Volume 1, Pittsburgh, PA, pp. 195-204.
||||V 'vihiiiriiiniinniiii I ill I iiiiiiiiiiiiiniP in i viiini n i iiinnni in i i nun in i i i i in in i inin M in inn i IIIIIIIIHI IN i n n n i HIM n in n i i i i nninniiii i nun ininin n inn n
r^epler, D.A. ^and E.C. McCleary, 1995. Successive Alkalinity-Producing Systems (SAPS). In the
" ---'! ":"1'1"1"'1; :|PrTOeeSngs1ofIhe TdP West Virginia Surface Mine Drainage Task Force Symposium,
':' ' j Morgantown, WV.
!
:; n'liiilliiil'ilMiF It*11!1!! M ,"|,|lr, 1,1ml. I !'* 'Flln'iitKni. '
1.1,1: ,i,,,i|.i" iiiill'ilLII'lli'iilir1',, I
, D.A. iand E.C. McCleary, 1997. Passive Aluminum Treatment Successes, In the
.SBB^^^^^^^^^^^^^^^^^^^^^^ ;i:/iijปp1ocdings ...... bfthe ..... 18tH West Virginia Surface Mine Drainage Task Force' Symposium,
,1=^ ..... ' ;;; :;,; fMorgantownl' W V.
jg^^r^LiP.j 19851' |Treatment of AcM Mine Water by Wetlands, fa Control of Acid Mine
] ...... 'flS! ..... Bureau ...... oT^nes ^rainaSon"clrci3'ar ..... 9627! ...... pp! ...... 3^5^!'""
, . ....... S,:L.P. ...... and ...... G.R. ...... Watzlaf, 1986., .Should, the ...... Discharge Standards for Manganese Be
'' ii|i|i|i,j? ''*Bป"" !"ซ iiMhC'! 'E" ปi! ilini .i !! : \,m ...... IS'S'MiS ill! .IhilS";,!!:!:!,"! '!n!p siw^iiiiilnni^ ................... , ....... pin ซ ........ ปซ ............. I*M ..... ซป .................. . ..... 11 " ...... ....... ...... ....... ป ............ ........ '*,, ................... ....... ............................ .................
i ........ Reexamined?, fa the Proceedings on Surface Mining, Hydrology, Sedimentology, and
,' ....... KY.PP"- 173:179;
i(::;iiii;;i! mm IIB^^^^^^^^^^^^^^^^^^^^^^^^^^ t'iiiK^^ n i:i;ป mmi iii^i !tH^^^^^^^^^
leinmann, R.L.P., G.R. Watzlaf, and T.E. Ackman, 1985. Treatment of Mine Water to Remove
Manganese. In the Proceedings on Surface Mining, Hydrology, Sedimentology, and Reclamation,
, KY, pp. 211-217.
"^-^Lehr, XH^T-E. Gass? WTA^.' Pettyjohn, and J. DeMarre, 1980.' Domestic Water Treatment,
McGraw-Hill gook Company, 264 p.
Manual
for Diversion Wells: A Low-Cost Approach for Treatment of Acidic Streams. Unpubished
''"I 1 ' . 'IIIIIM^^^^^^^^^ ..... Hi1 ........ ''iKrllK (lill. ' ..... ! :!!: .m ....... ,:, .............. m, ............. ...... ],. ............... : , ......................... ...... . ILL ..... ...... in ................... :ป, '. .................... , ซu ...... : ......... nr ..... - ........... ............. . ........... ....... .............. ,< .......... . ..... ............ , :r <: 11 , '-mil
23 p.
r ........................... ....................... M ., ........... ,. ............ ................................... ........... , ............... , ,;,, ........ .......... ........... . i, ....... ................. .................
'- '^ IMcfatire, P.E. and H.M. Edenborn, 1990. The Use of Bacterid Sulfate Reduction in the
i Trsatnigni fif I)r,ainage from Coal' Mines, fa the JProceedings of the 1990 Mining and
,ation Conference and Exhibition, Charleston, WV
'
. 409-415.
* ....... a . .
rjn. R.W., R.S. Hedin, and G.R. Watzlaf, 1991. A Preliminary Review of the Use of Anoxic
i" IIIIK iiiLfliniiiiiiiiiiinn ...... in liiniiiiiinlnniiiiiiiiijii' iiiiiiiiiiiniHiiii "'HiipiinniiiiiiiainnniiinnnnnniNiiiitiuiiiiii'Piiii'niiininiiifi WIMIIR wi'1,1 ,ซ ....... n-RLip ii^iiTiiiHinii'iiiiiiiiniiiniii': t. -wj'aiiirifi ..... rani,,1' ' / isiiiiiisiiiiiLifiniKiiii'iiiiiii:;1 iiiffiniiiiii iiininniiiiiiiihiihiiHi;, ' ....... ipiiiiiiiiiiii ..... n ....... nini ..................................... j,i ............... .1,1. > \m .................. >' ......... < ................... << ป< ........ <<< ......................... fu " '
ipiejtone ...... Drains;ii|i ..... the ...... P^sjiye .Treatment of Acid Mme, Drainage, fa the Proceedins of the 12
/esf ..... vKrgmik Surface Mine Drainage Task Force Symposium, Morgantown,
Passive Treatment
I 111 ..... 1
III1
Illllli1 1 III 11
Ill PI 111
IIK ill''
"i1 IK
1; ..... HT!bm>ilftSB4'a*l;1i*i!!*i3lปl,llurr.1B':! '
' ; : ..... ;ซ
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Coal Retnining BMP Guidance Manual
Nichols, H.L. 1976. Moving the Earth. North Castle Books, Greenwich, Connecticut.
Rose, Arthur, personal communication with Jay Hawkins, 1999. Details available from the U.S.
Environmental Protection Agency Sample Control Center, operated by DynCorp I&ET, 6101
Stevenson Avenue, Alexandria, VA, 22304.
Skousen, J., B. Faulkner, and P. Sterner, 1995. Passive Treatment Systems and Improvement of
Water Quality, In the Proceedings of the 16th West Virginia Surface Mine Drainage Task Force
Symposium, Morgantown, WV.
Smith, S., 1982 Sulfur Bacterial Problems Revisited, Water Well Journal, NWWA, pp. 44-45.
Spratt, A.K. and R.K. Wieder, 1988. Growth Responses and Iron Uptake in Sphagnum Plants
and Their Relation to Acid Mine Drainage Treatment, U.S. Bureau of Mines Information
Circular, IC9183, pp. 279-290.
Stark, L.R., S.E. Stevens, H.J. Webster, and W.R. Wenerick, 1990. In the Proceedings of the
1990 Mining and Reclamation Conference and Exhibition, Charleston, WV, pp. 393-401.
Vail, W.J. and R.K. Riley, 1997. The Abatement of Acid Mine Pollution Using the Pyrolusiteฎ
Process, In the Proceedings of the 19th Annual Conference of the Association of Abandon Mine
Land Programs, Canaan Valley, WV.
Watten, B.J. and M.F. Schwartz, 1996. Carbon Dioxide Pretreatment of AMD for Limestone
Diversion Wells. Proceedings of the 17th West Virginia Surface Mine Drainage_Task Force
Symposium, Morgantown, WV. pp. J-l to J-10.
Wieder, R.K., 1988. Determining the Capacity for Metal Retention in Man-Made Wetlands
Constructed for Treatment of Coal Mine Drainage. U.S. Bureau of Mines Information Circular,
IC9183, pp. 375-381.
Ziemkiewicz, P.P., and D.L. Brant, 1997. The Casselman River Restoration Project, In the
Proceedings of the 18th West Virginia Surface Mine Drainage Task Force Symposium,
Morgantown, WV.
Ziemkiewicz, P., J. Skousen, and R. Lovett, 1994. Open Limestone Channels for Treating Acid
Mine Drainage: A New Look at an Old Idea. Green Lands, NMLRC, pp. 36-41.
Ziemkiewicz, P.P., D.L. Brant, and J.G. Skousen, 1996. Acid Mine Drainage Treatment with
Open Limestone Channels. Passive Treatment Systems and Improvement of Water Quality, In
the Proceedings of the 17th West Virginia Surface Mine Drainage Task Force Symposium,
Morgantown, WV. pp. M-l to M-15.
Passive Treatment
4-39
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Coal Remining BMP Guidance Manual
i;-' " I
: !ซ!*'.
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4-40
Passive Treatment
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Coal Remining BMP Guidance Manual
Section 5.0 Integration of Best Management Practices
As the preceding sections have illustrated, Best Management Practices (BMP) are seldom
employed singly. Furthermore, it is virtually impossible for some BMPs to be employed without
the use of other integral and complementary BMPs. For example, if regrading of dead spoils is
performed, corresponding revegetation would also be needed; partial underground mine
daylighting requires sealing of undisturbed mine entries at the final highwall; and daylighting
commonly entails the cleanup of acid-forming materials surrounding the remaining pillars, which
in turn need to be special handled. The efficiency of many BMPs can be augmented by
employing others which complement them. The ability of regrading of dead spoils to preclude
surface water infiltration can be improved when combined with diversion ditches, lined channels,
stream sealing, or spoil capping. The efficacy of special materials handling of acid-forming
materials can be aided by special water handling facilities and alkaline addition.
Past mining practices, prior to the initiation of the Surface Mining Control and Reclamation Act
(SMCRA), dealt mainly with extracting coal as inexpensively as possible. Little attention was
paid to the environmental impacts of the active operation, much less the condition of the site
after mining was completed. The need for employing multiple BMPs is driven by site
characteristics such as the condition and amount of prior land disturbance, acidity of overburden,
and the extent of abandoned deep mines, and by requirements to prevent further degradation by
taking additional, pollutional countermeasures. These abandoned mines often require multiple
BMPs to effect adequate reclamation and pollution mitigation.
There are two basic mechanisms by which BMPs work to decrease the contaminant load: 1) by
physically decreasing the flow of the discharge, and 2) by geochemically improving the water
quality (decrease the contaminant concentration). Some BMPs perform both functions to varying
degrees simultaneously. Sealing of deep mine entries will inhibit the flow of ground water as
well as prevent the infiltration of oxygen into the mine. Revegetation will inhibit water and
Integration of BMPs
5-1
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Coal Rdmining BMP Guidance Manual
oxygen infiltration into the backfill as well as impede erosion and sedimentation. It can also
increase the amount of CO2 available in spoil and therefore can positively influence carbonate
lllii '.! ,|'i '' " 'jlllllil '' r'.IV'l ' , ' 'ii |! ' i, . '. i!!! . , .iM , .H1, , ' i 'I',,1'1' ' I.!!1 ,,ii "S'i '' ,|.<1!, (" i1', l|i ' I,., ,,' I ' ' ปll en1,.. , Jill "I I'll1 ป ! ' II II
dissolution; The choice of which BMPs are needed to decrease the pollutant loads is site-specific
and cannot be' determined using cookbook methodology. The experience and knowledge of
permit preparers and reviewers are the major factors in the successful selection, design, and
implementation of renaming BMPs.
Some of the BMP combinations have been discussed in preceding sections. This section will
discuss these combinations in more detail, as well as cover BMP combinations not previously
discussed. This section was written to cover the benefits of combining BMPs. It is not the
intention of this section to discuss the benefits of all possible BMP combinations, but rather to
discuss the overall benefits of combining BMPs. It is likely that there are some beneficial
combinations not specifically addressed.
Regrading and Revegetation
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Regrading and revegetation work hand-in-hand to decrease pollution loadings both physically
and geochemically. This BMP combination functions physically by reducing the amount of
surface water introduced into the backfill and, geochemically by altering spoil pore gas
composition that impacts the weathering of carbonates and pyrite. Spoil regrading eliminates
exposed, highly permeable material and closed contour depressions, both of which, when
unchecked, facilitate direct infiltration into the spoil of surface water, and promote surface
runoff.
The addition of soil and vegetative cover over regraded spoil also works to enhance the inhibition
of surface water infiltration. Soils will allow some surface water infiltration, but a great deal of
the infiltrating water will be held in the soil horizon until it is used by plants. The structure of
soil cover is such that significant quantities of water are preferentially retained. The soil holds
water near the ground surface which permits direct evaporation. The addition of vegetative cover
further inhibits water infiltration into the underlying spoil. The plants, during the growing
~ง-2 Integration of BMPs
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Coal Remining BMP Guidance Manual
season, will take up the water in the soil and transpire it back into the atmosphere. Certain types
of plants will promote additional runoff, especially during high intensity precipitation events.
Use of biosolids can greatly enhance the vegetative growth and cover percentage, which in turn,
will promote greater water use by the plants. However, biosolids should be applied with the
provision that the nutrients that they provide may promote significant growth of iron-oxidizing
bacteria, thus possibly increasing acid production. However, this effect may be transient and
relatively insignificant (Cravotta, 1998). The application of biosolids in Pennsylvania's
Remining Site Study appears to have resulted in a positive influence on water quality (Section 6,
Table 6.3a).
The more stable regraded surfaces will also function geochemically by inhibiting the introduction
of oxygen at depth and by retaining carbon dioxide. Regrading of several spoil piles into one
large backfilled area results in less surface area and fewer slopes for atmospheric exchange. In
addition, thicker spoil will make it more difficult for oxygen penetration at depth. Soil cover and
plant growth tend to further preclude oxygen infiltration and retention of carbon dioxide in the
underlying spoil. In addition, the decay of organic matter in the soil utilizes oxygen, further
suppressing deeper oxygen infiltration.
Combining implementation of diversion ditches and stream sealing above the mined area and/or
across the surface of the backfill (typically implemented on sites with severely acidic
overburden) can augment the efficiency of regrading and revegetation. Capping the site with a
low permeability material can also reduce surface water as well as oxygen infiltration.
There are cases where regrading and revegetation alone are not adequate for pollution reduction.
If the regraded spoil is determined to be inherently acidic and the acid-forming materials are
widely disseminated, other BMPs such as alkaline addition, mining into alkaline strata (if
present), or alkaline redistribution may be necessary. Another BMP that has been used in these
circumstances is the installation of induced alkaline recharge structures.
Integration of BMPs
5-3
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,1 ', ' "'II '"'"I'l' '' f
Coal Remining BMP Guidance Manual
" Daylighting""
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T_here are several BMPs that can be implemented in conjunction with daylighting to enhance the
impact on discfiarge pollution loadings. Daylighting commonly generates considerable acid-
j, ' . v i't i1"?"! >'.' ,' n'l":*, ;','!':!; .:,. : ''''i -!,- .;''**'i'iiiiiii/,; /: & i,ii*.j ,;?!; ws1,-,1 it vMN at1
forming materials (waste coal, immediate roof rock, etc.) when the area around pillars is cleaned
prior to the excavation of the coal. This acidic material generally requires special handling to
further prevent AMD formation. If the amount of acid-forming materials removed from around
the coal pillars is significant, this material may need to be removed from the site and disposed of
off-site. Additionally, because of the fair amount of acid-forming material that is usually spoiled,
alkaline addition may be needed to offset the acidity potential. The alkaline material may also
require special handling. Depending on the situation, alkaline material may need to be placed
either above the acidic material to prevent AMD formation, or below or within the acidic
material to neutralize AMD already formed. Alternatively, mining may need to progress to a
predefined overburden thickness to allow disturbance of significant quantities of naturally
occurring alkaline rocks above the coal.
If the daylighting does not eliminate all of the abandoned underground mine, other BMPs may be
used to aid pollution abatement. The mine entries will need to be sealed to exclude the lateral
infiltration or discharge of ground water as described in Section 1.0. Mine entry seals also inhibit
the infiltration of atmospheric oxygen to or from the underground mine. If considerable water is
stored in and is flowing through the underground mine, a drain may need to be piped from behind
the seals through the backfill, thus diverting the water away from the site.
LCoal Refuse R
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Coal Remining BMP Guidance Manual
Other BMPs can also be employed to further the pollution abatement. In cases where the coal is
reprocessed on-site and the waste rock is returned, bactericides may be an option to inhibit pyrite
oxidation prior to covering and revegetating the pile. Bactericides can be applied as the waste
material is transportedtvia a conveyor belt. Sites involving coal refuse removal or reprocessing
are also prime candidates for alkaline addition. Coal refuse seldom has any natural alkalinity-
producing ability, therefore any alkaline material added should be beneficial in AMD prevention
or neutralization.
Prior to remining, coal refuse piles commonly allow considerable water and oxygen infiltration.
These piles are poorly vegetated and typically do not promote runoff. Regrading, soiling and
revegetation of the waste material will prove beneficial in many respects, not the least of which is
to promoting runoff and reducing water and oxygen infiltration. Surface water control structures
(e.g., diversion ditches) and the capping of the refuse with a low permeability material can also
aid the reduction of pollution loads.
Remining operations involving complete removal of the coal refuse will nearly completely
eliminate the AMD production. However, all of the refuse is seldom removed. Refuse is
screened and the fine material, which contains most of the coal, is sent to the power plant. The
larger materials remain behind. There are usually minor amounts of refuse left in place. Other
BMPs that can prove useful with these types of operations are alkaline addition, regrading and
revegetation, and surface water control. Coal combustion waste (CCW), a byproduct of burning
the refuse, is often returned to these sites. CCWs typically contain some alkaline material
resulting from the addition of limestone during the burning process, thus providing some acid-
neutralization potential.
Special Handling with Surface and Ground-Water Controls
A critical component of successful special handling of acidic and alkaline material is
understanding the ground-water system. If the ground water can be controlled, special handling
will more likely prove successful.
Integration of BMPs 5^5
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Coal Remining BMP Guidance Manual
In cases wEere the acidic material is placed in pods in the backfill and are intended to be located
above the fluctuating water table, ground-water control and, to some extent, surface water control
can be used to suppress the water table and dampen water table fluctuations. Highwall drains
arid highwall diversion wells can be employed to intercept laterally infiltrating ground water, and
floor drains can be used to collect and rapidly remove ground water. Both of these BMPs will
work to suppress the water table (Figure 5.0a). Mine entry sealing and diversion (piping or
channeling) of underground mine waters will also aid in this respect. The use of surface water
diversion ditches, spoil capping, and/or stream sealing will aid in suppressing the water table
through reduced vertical infiltration. Capping and revegetation may aid geochemically by
" - ,.' , ;, ";;i .:''<,; ..; - .: ' ':l:::; , :; : : 'I ,,'i, .i-iri >' : -.UK'/ ;; . - '.,. : *. ^is
inhibiting atmospheric oxygen infiltration into acidic pods, reducing pyrite oxidation, and
reducing the amount of water available for transport of acid materials.
Figure S.Oa: Water Table Suppression in Conjunction with Special Handling of Acidic
Material
I If
Possible Watertable
with Floor Drain
Pods of Acid-Forming
Materials
Possible Watertable
without Floor Drain
Floor Drain
tl,!'
5-6
Integration of BMPs
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Coal Remining BMP Guidance Manual
Conversely, if alkaline material is specially handled within the backfill, it may be beneficial to
divert extra water through these areas to generate additional alkalinity. This is similar to induced
alkaline recharge (Section 2.3). In cases of special handling of alkaline materials, there are
ground- and surface-water controls that can be employed to increase the amount of water that
encounters the alkaline material. Chimney drains can be used to funnel water from the surface
toward alkaline zones. Additionally, the drains themselves can be comprised of limestone or
other alkaline rock. The surface of the reclaimed site can be configured to promote selective
infiltration. Small impoundment areas can be created to allow surface water to collect and
infiltrate in areas .above alkaline-rich areas.
Alkaline material can be placed in areas that will be within the main ground-water flow paths.
Ground water will flow primarily along the path of least resistance, which in mine spoil is
commonly the buried spoil valleys. The larger spoil particles tend to roll off the sides and collect
at the valleys between spoil piles. Thus, these valleys tend to be highly transmissive zones that
facilitate significant ground-water flow (Hawkins, 1998). Placing alkaline material in these
valleys, prior to reclamation, will likely enhance increased alkalinity production. Conversely, the
acid-rich pods would be best placed in the center of the ridges as far away, both vertically and
horizontally, from the highly transmissive zones as possible, but such that they will not be too
near the surface. These optimal placement locations are illustrated in Figure 5.0b.
Integration ofBMPs
5-7
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Coal Remining BMP Guidance Manual
..,, ., ,:.,,:: ..,,.:,
Figure S.Ob: Optimal Location for Special Handling of Acidic and Alkaline Materials
Schematic Drawing of a Backfilled Site
*^v*/^AAi/*/*/^/*A^^>*>fcj^,A/^>VA<^^^/*^^^ปi^*
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Good Locations for Alkaline Good Locations for Acidic
Material Placement Material Placement
H"
For selected sites where acidic material placement is below the water table, the use of water
i
infiltration control BMPs can be beneficial. It is critical to keep this acidic material under
Saturated conditions and out of contact with atmospheric oxygen. Given the hydrogeologic
Conditions within the Appalachian Plateau, many surface mines are located above the regional
j, . ,, ;; , .. ,,, /: , ,-, . ; . , , ;;,; , ; , . ;[;;,, ; . ; ; , ^ , . . , ,
water table and local water tables are relatively thin. Keeping acidic material under saturated
conditions is extremely difficult. However, if large amounts of water can be induced to infiltrate
t
into and held within spoil, it can help maintain a minimum water level in the backfill. Chimney
drains and induced alkaline recharge structures can be used to promote infiltration. In addition,
jri/ ... ;;: ,. j;. fiSij ;M i ',";!.I' :" ' t'.t!1,1'1 . "i:"'i A'.1'. : fb''!',, '. t:';' f?"''"" :'i' ' ':.;"'" !.:',ii " ;': ?'
the surface of the reclaimed site can be configured to promote direct infiltration, and small
impoundment areas can be created to allow surface water to collect and infiltrate into the spoil.
Engineered highwalls can also be created to aid infiltration. For example, bench slopes can be
designed to induce infiltration by directing water back toward the highwall, permitting small
impoundments or infiltration zones rather than promoting runoff. Once ground water has
5-8
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Coal Remining BMP Guidance Manual
infiltrated the backfill, as much ground water as possible should be stored to maintain a high
water table and saturated conditions. Surface mining below the regional ground-water flow
system should allow acidic material submergence, because the water table will commonly re-
establish itself and be maintained at a sufficient level. Because it is common in the Appalachian
Plateau for undisturbed strata to have hydraulic conductivity values two orders of magnitude
lower than the associated spoil (Hawkins, 1995), if the final highwall is down dip from the
mining operations, substantial ground water should impound behind it. In these situations, acidic
material should be placed against the highwall to maximize the potential for continual
submergence. If the highwall is up dip of the mining operations or the strata are nearly level,
maintaining a high water table will be extremely difficult, because the ground water will tend to
drain more freely at the toe of the spoil. Therefore, subaqueous placement of acidic materials
will likely not be an option. If hydrologic controls (e.g., low permeability zones) can be installed
in the backfill to inhibit ground-water movement and subsequent discharge, subaqueous
placement of acid-forming materials may be viable through maintenance of an elevated water
table. A thorough knowledge of site hydrogeologic conditions is required to attempt a "dark and
deep" placement or saturated condition of acid-forming materials. However, even with these
ground-water controls, a protracted drought may cause the water table to drop below the level of
the acidic material, which will likely make worsen the water qualitiy.
Alkaline addition also can be combined with the use of low permeability CCW. CCW, when
used as a capping, entry seal, or grouting material, can be used with other BMPs to inhibit water
movement and provide the ground water with some alkalinity. CCW also can be beneficial when
applied to acidic pit floors by sealing the pit floor from ground water.
Miscellaneous BMP Combinations
The use of passive treatment systems can be beneficial to virtually all remining sites with
continuing post-remining. AMD discharges, regardless of the BMPs employed during mining.
However, some types of passive treatment can be integrated into the reclamation plan. These
Integration of BMPs ~~ " ~ 5.9
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Coa/ Remining BMP Guidance Manual
passive treatment systems include installing an ALD as a pit floor underdrain through the
backfill and, configuring the regrading and revegetation to create a wetland.
Mining into enough cover to encounter alkaline strata can also be beneficial for special handling
pf acidic materials. Acidic materials, when strategically placed above the water table, commonly
need to be well above the pit floor (e.g., >15 to 20 feet) and deep enough to be removed from the
impacts of infiltrating atmospheric oxygen. Therefore, a substantially thick backfill is required
to maintain the acid-forming materials within these narrow guidelines. Mining into additional
cover may yield the necessary spoil thickness to properly handle acid-forming materials.
! . i ',,;; | 'a i . , ',. ' . ,, . ., . ,,-. ,, i,) ',ป! .; ;||i "' ,.,! ;: '' , ' :' ' 'l; " ' "i " |'.'(
Capping of mine spoil with a low permeability material can aid the alkalinity production of
inherent, redistributed, and added alkaline materials in the backfill. These caps can inhibit the
exchange of gases from the backfill to the atmosphere and vice versa. Therefore, the caps will
prevent CO2 in the vadose zone from escaping, which will promote higher alkalinity production.
Summary
BMPs are seldom employed alone. Because of the frequently multifaceted nature of abandoned
surface and underground mines, BMP combinations are required to enhance reclamation and to
1 ! '! ' ' ' "" ',,' '"lill ' '"II . !' ' , , '. i '' , '"',:, i, ,, ' ' ,! ,11 ' '" ,,,:l!i|| , , ' ,! U i V ", \ I!" 'V"|| i :,i,l " ป ' i , , In.',,,! ', ' ', I, ': l!'1, '., i.U
preclude the potential for greater pollution loadings due to remining. Some BMPs, when used in
conjunction with others can enhance the pollution load reduction efficacy.
This section does not cover all potential BMP combinations, but does review some of the more
common combinations being implemented during remining operations. BMP plans do not lend
themselves to a preset methodology or cookbook formula. Each remining operation requires a
BMP plan that stems from site-specific conditions that are contingent on the background and
experience of the remining permit and BMP plan preparer and reviewer. Factors such as the
i
extent of previous mining, configuration of the abandoned site, geochemistry of the overburden,
site hydrology, and topography all impact the formulation of an effective BMP plan.
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Coal Remininz BMP Guidance Manual
References
Cravotta, C.A., 1998. Effect of Sewage Sludge on Formation of Acidic Ground Water at a
Reclaimed Coal Mine. Ground Water, vol. 36, no. 1, pp. 9-19.
Hawkins, J.W., 1998. Hydrogeologic Characteristics of Surface-Mine Spoil, Chapter 3 of Coal
Mine Drainage Prediction and Pollution Prevention in Pennsylvania, Pennsylvania Department of
Environmental Protection, Harrisburg, PA, lip.
Hawkins, J.W., 1995. Impacts on Ground Water Hydrology from Surface Coal Mining in
Northern Appalachia. In the Proceedings of the 1995 Annual Meeting of the American Institute
of Hydrology, Denver, CO. pp. IMWA-32 - IMWA-43.
Integration ofBMPs
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Coal Rtimining BMP Guidance Manual
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Coal Remining BMP Guidance Manual
Section 6.0 Efficiencies of Best Management Practices
Determination of the efficiencies of Best Management Practices (BMP) is best performed using
data that accurately represent water quality and pollution loading before, during, and after
remining has occurred. Water quality and flow data that are used to determine baseline pollution
loading for pre-existing discharges can be compared to data collected to monitor the same
discharges after mining operations have been completed. Because the effects of both remining
operations and associated BMPs are generally not immediate and can continue well beyond mine
closure, it is important to consider water quality and flow conditions for a period of time (e.g., >
2 years) following site closure.
Site-specific efficiency statements for BMPs have been included in each section of this Guidance
Manual. The purpose of this section is to: 1) present observed results of the effects of the
implementation of 12 BMPs at over 100 remining sites in Pennsylvania using existing data, and
2) analyze these data, using statistical methods, in order to predict BMP efficiencies at remining
sites throughout the Appalachian coal region. Efficiencies are presented for the following BMPs,
as implemented individually or in combination:
Regradlng: the restoration of positive drainage to pre-Surface Mining Control and Reclamation
Act (SMCRA) surface mined areas. Regrading can be to approximate original contour (if
adequate spoil is available) or terraced (if existing spoil is inadequate or if terracing will result in
a higher land use).
Revegetation: the establishment of a diverse and permanent vegetative cover on inadequately
vegetated pre-SMCRA surface-mined areas that is adequate to control surface-water infiltration
and erosion.
Daylighting: the exposure by surface mining of a deep-mined coal seam, with the purpose of
removal of the remaining coal.
Special Handling of Acid-Producing Materials: the selective placement of acid-generating
overburden rock at a position within the backfill that is advantageous for reducing the amount of
acid that would otherwise be generated from that rock.
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Coal Remitting BMP Guidance Manual
Alkaline Addition: the importation of off-site calcareous material to a mine site. Alkaline
addition is used in a variety of circumstances, particularly where a mine lacks sufficient
naturally-occurring calcareous rock, but does contain a sufficient amount of pyritic material that
could produce mine drainage pollution in the absence of neutralizes. Alkaline addition is
measured as tons of CaCO3 equivalent/acre.
Water Handling Systems: refers to any BMP that is specifically designed to: 1) reduce the
amount of surface water that could infiltrate into the spoil and become ground water, or 2)
channel ground water through spoil with the purpose of reducing water contact time with spoil
and/or lowering the ground water table or preventing ground water from entering the spoil.
Passive Treatment: means of treating polluted mine drainage chemically and/or biologically
such that metals concentrations are oxidized or reduced and acidity is neutralized. Compared
with conventional chemical treatment (the typical alternative), passive methods generally require
more surface area, but use less costly reagents, and require less operational attention, power, and
rnaintenance. ... ;
Coal Refuse Removal: the elimination or reduction of abandoned coal waste piles. This
material is'typicaliy sent to power plants for generation of electricity, fii addition to the
elimination or reduction of the size of the pile, the site of disturbance Is regraded arid
revegetated.
Biosolids Addition: the application of nutrient-rich organic materials resulting from the
treatment of sewage sludge (a solid, semi-solid or liquid residue generated during the treatment
of domestic sewage in a treatment works) as a soil amendment for enhancement of plant growth
on surface mines.
Mining of Highly Alkaline Strata: the encountering and mixing of naturally-occurring
calcareous rock during the mining process. The mining plan may have to be adjusted to ensure
that sufficient calcareous rock is encountered.
Alkaline Redistribution: the process of taking excess calcareous material from a portion of a
mine and placing it in areas of the mine that lack calcareous materials. Typically, these areas
lacking calcareous materials would not produce acceptable post-mining water quality without the
addition of the calcareous material.
BMP efficiencies presented in this section are based on data provided by Pennsylvania
Department of Environmental Protection (PA DEP) as a remining site study (PA Remining Site
Study). The database from this study existed prior to the initiation of this evaluation, and
includes summary water quality information and associated BMPs only. Therefore, factors that
may have affected discharges in addition to the associated BMPs (such as compliance history)
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Coal Remining BMP Guidance Manual
were not considered in this evaluation. The PA Remining Study was not specifically designed
for the purposes of evaluating or determining the BMP efficiencies presented in this section. It
is, however, the largest database available on completed remining sites and includes baseline
data, post-mining data, and a record of BMPs used on 113 mine sites.
In spite of certain limitations of the data evaluated, these data include 231 discharges from 112
closed remining operations, and are the most comprehensive compiled to date regarding the
efficiency of remining. These data are considered highly suited for the determination of BMP
efficiencies, and the BMP efficiencies that have been predicted using these data can be
considered the best available at this time. The advantages of this data set include:
Over 100 different remining sites and over 230 pre-existing discharges are represented.
Baseline data include monthly samples, typically for one year.
Post-mining data include at least one year of monthly sample results.
Post-mining data represent conditions following reclamation of remining sites.
BMPs implemented are identified for each discharge.
Water quality data represent ground-water discharges that are hydrologically connected to
the mine.
Limitations
It is important to note while reviewing this section that, although the data set used is the most
extensive available on remining at this time, there are some limitations to its use for evaluating
BMP efficiencies.
The data is specific and exclusive to remining operations in the Pennsylvania bituminous
coal regions. Although hydrologically and geologically very similar, remining in other
parts of the Appalachian coalfields may exhibit slight differences.
Efficiencies of BMPs
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Coal Reminmg BMP Guidance Manual
All permits were State-approved, Rahall remitting permits and sites have been reclaimed
to at least Stage n bond release standards. During permit application review, for
operations thought to be potentially environmentally detrimental (i.e., resulting in
increased pollution loadings), permits are either denied or amended to preclude
degradation.
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This data set does not include non Rahall-type remimng operations where pre-existing
discharges are subject to statutory effluent limitations.
No discharge data from mining on areas previously unmined, or discharge data from areas
unaffected by BMPs (i.e., control data) were included.
All sites all had at least monthly water quality analysis and flow measurement
requirements for determining baseline, as well as during-mining and post-mining
monitoring data. However, no compensation has been applied for sampling through
periods of abnormal precipitation (well above or below the average).
At this time, only contaminant loading and flow data are available. Review of
concentration data would permit a more rigorous determination of BMP efficiency.
Determination of whether a change in flow or contaminant concentration effected the
change in load would permit determinations as to whether a specific BMP made a
j
physical (flow) and/or geochemical (concentration) difference. These data may be
available in the near future and an in-depth analysis and discussion may follow.
For mines reclaimed only recently, the post-mining data may not be fully representative
of equilibrium conditions. During this early period (~ 2 years), the water table is
rebounding and discharge rates may be below those that will occur once the water table
has reached equilibrium. Because the most recently collected 12 months of data (at the
time of database compilation) was used in this study, most sites have been reclaimed for a
I
number of years and the water table should have stabilized in the backfill.
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Coal Remining BMP Guidance Manual
6.1 Pennsylvania DEP - Remining Site Study
In 1998, Pennsylvania DEP evaluated water-quality and flow data for 248 pre-existing discharges
from 112 remining sites that had been reclaimed to at least Stage n bond release standards
(completely backfilled and revegetated). The remining sites were scattered throughout the
bituminous coal region of the state and most heavily concentrated in the southwestern counties.
The most recently available 12 months of pollution loading and flow data were compared against
baseline loading and flow data (usually 12 months) for each pre-existing discharge. The same
statistical test used to detect significant increases in pollution load (Tukey, 1976; PA DER, 1988)
was used to determine whether there were significant decreases in pollution load. In addition, the
current (or most recently available) median pollution load was calculated in order to quantify the
actual increase or decrease in pollution load. This analysis was conducted for acidity, total iron,
total manganese, and total aluminum loadings.
Results of the analysis for each individual discharge or discharges identified by and combined
into hydrologically-connected units were entered into a database. The database-also identified
the best management practices employed during remining operations that were expected to have
an impact on the water quality of that discharge. A single surface mining permit, more often than
not, includes several individual discharges or hydrologic units and implements multiple BMPs.
Some or all of the employed BMPs may be applicable to each discharge or hydrologic unit.
Therefore, analysis of BMP effect on discharges was performed at the discharge or hydrologic-
unit level, not at the permit level.
Of the 248 discharges included in the database, some could not be used for BMP efficiency
analyses due to missing or unavailable information or data. Six monitoring points did not have
baseline water quality data for any parameter, most likely due to an absence of flow. Ten other
discharges did not have any associated BMP information. Therefore, the total number of
discharges used in the BMP efficiency analyses was 231, from 109 permits.
Efficiencies of BMPs
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Coal Returning BMP Guidance Manual
ซI;"
Sulfate loadings and flow rates were also analyzed in this section to yield insight as to which
BMPs may have caused the observed loadings changes. Sulfate loading trends may indicate if
changes in loading rates of acidity, iron, manganese, and/or aluminum are due to geochemical
changes in acid mine drainage (AMD) production (increases or decreases in pyrite oxidation).
Sulfate ions are a conservative indicator of AMD production. Flow rate data may indicate
whether changes to contaminant loadings are due to changes in the flow rate. These two
parameters can in turn indicate if an improvement in water quality is related to a particular
geochernically-based or physically-based BMP.
6.2 Observed Results
The database was used to summarize the number of discharges which showed statistically
Significant increases, decreases, or no change in pollution load and to compare the aggregate
(combined) median pollution load. Statistical significance is determined by comparing the
baseline upper and lower confidence limits about the median pollution load against the upper and
j;
lower confidence limits about the post-mining median. BMP effects on discharges were rated as
|i,i;: i ,!' ' "ii !!' .i11!1!' 'i, nil ' ' II, ' ' , ," i, 'i' '!" ' I! "H '',' '"II '" ' ', , ,''"''!!' ,1.
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6-6
No significant difference - If the baseline and post-mining confidence intervals overlap,
then there is no statistically significant difference and the median pollutant loading of the
discharge is considered unchanged.
Significantly degraded - If the post-mining lower confidence limit exceeds the baseline
,!' "if ....... liiJi ,' : ; '';:- ' : ,' - "'' ........ ' :'. ', '> ' ' .'"i it"" ,' ' , '':>' i ' , if I,:'!' ' ' . . , " ..... ' ". !
upper confidence limit, then there is a significant increase in median load.
Significantly improved - If the post-mining upper confidence limit
baseline lower confidence limit, there is a significant decrease in
is lower than the
median load.
Eliminated - If the post-mining upper confidence limit was zero, the
considered to have been eliminated. This does not necessarily, mean.
pollution load was
that the discharge
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Coal Remining BMP Guidance Manual
was physically eliminated, only that with 95 percent confidence, the median pollution
loads were zero.
This analysis was performed for each discharge affected by any of the 12 specific BMPs listed
earlier in this section. The results of the observed BMP effects on pre-existing discharges are
summarized by BMP and parameter in Table 6.2a.
Most discharges (or hydrologic units) were affected by multiple BMPs. For that reason, BMP
effects on a single discharge may be represented in Table 6.2a under several different BMPs. For
example, surface regrading, revegetation, and daylighting may have been implemented in an area
affecting a single discharge. In Table 6.2a, the water quality results for that discharge would be
represented in the summary results for each of these BMPs separately. Therefore, changes in
pollution-loading rates may not be attributed solely to that BMP, but may have been affected by a
group of BMPs. Table 6.2b summarizes the observed effects of BMPs on discharges by BMP
group and parameter.
Efficiencies of BMPs
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BMP Guidance Manual
Table 6.2a: Pennsylvania Remining Permits, Summary of Observed Water
Quality Results by Individual BMP (Appendix B, Pennsylvania
Remining Site Study)
Water Quality Results - Overall
Acidity
# Percent of
Discharges I Discharges
Manganese
Discharge eliminated
Significantly improved
No significant difference
Signifbantly degraded
Total for parameter
' "Iron
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Sulfate
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
43
57
123
2
225
49
37
110
11
207
43
47
116
24
230
19.1%
25.3%
54.7%
0.9%
23.7%
17.9%
53.1%
5.3%
18.7%
20.4%
50.4%
10.4%
# Percent of
Discharges [Discharges
Discharge eliminated
' i ' | P "Mi i,,' , , ' '',!,,,.
Significantly improved
No significant differenc
Significantly degraded
Total for parameter
Aluminum
Discharge eliminated
Significantly improved
No significant differenc
Significantly degraded
Total for parameter
Flow
Discharge eliminated
Significantly improved
No significant different
Significantly degraded
Total for parameter
32
.,
31
e 78
14
155
21
23
3 69
4
117
42
- ' 54 '
3 122
13
231
20.6%
20.0%
50.3%
9.0%
17.9%
19.7%
59.0%
3.4%
18.2%
23.4%
52.8%
5.6%
Efficiencies of BMPs
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Coal Remining BMP Guidance Manual
Water
Acidity
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Iron
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Sulfate
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Quality Results by BMP
# Percent of
Discharges Discharges
4 36.4%
3 27.3%
3 27.3%
1 9.1%
11
5 45.5%
1 9.1%
4 36.4%
1 9.1%
11
5 45.5%
1 9.1%
4 36.4%
1 9.1%
11
Water Quality Results by BMP
Acidity
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Iron
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Sulfate
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
# Percent of
Discharges Discharges
11 16.9%
11 16.9%
43 66.2%
0 0.0%
65
13 21.7%
9 15.0%
37 61.7%
1 1.7%
60
14 20.9%
11 16.4%
36 53.7%
6 9.0%
67
- Alkaline Addition > 100 tons/acre
Manganese #
Percent of
Discharges I Discharges
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Aluminum
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Flow
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
- Alkaline Addition < 100 tons/acre
Manganese #
1 16.7%
0 0.0%
3 50.0%
2 33.3%
6
0 0.0%
0 0.0%
1 100.0%
0 0.0%
1
4 36.4%
3 27.3%
3 27.3%
1 9.1%
11
Percent of
Discharges Discharges
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Aluminum
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Flow
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
8 20.5%
5 12.8%
22 56.4%
4 10.3%
39
5 19.2%
2 7.7%
19 73.1%
0 0.0%
26
14 20.9%
9 13.4%
41 61.2%
3 4.5%
67
Efficiencies ofBMPs
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Coal Remining BMP Guidance Manual
m : i i
Water Quality Res
Acidity #
Discharges
Discharge eliminated 5
Significantly improved 0
No significant difference 1
Significantly degraded 0
Total for parameter 6
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6-10
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Coal Remining BMP Guidance Manual
Water Quality Results by BMP - Coal Refuse Removal
Acidity #
Discharges
Discharge eliminated 2
Significantly improved 4
No significant difference 3
Significantly degraded 0
Total for parameter 9
Iron
Discharge eliminated 0
Significantly improved 2
No significant difference 4
Significantly degraded 1
Total for parameter 7
Sulfate
Discharge eliminated 0
Significantly improved 2
No significant difference 7
Significantly degraded 0
Total for parameter 9
Percent of Manganese #
Discharges Discharges
22.2% Discharge eliminated 0
44.4% Significantly improved 0
33.3%, No significant difference 5
0.0% Significantly degraded 1
Total for parameter 6
Aluminum
0.0% Discharge eliminated . 0
28.6% Significantly improved 2
57.1% No significant difference 4
14.3% Significantly degraded 0
Total for parameter 6
Flow
0.0% Discharge eliminated 0
22.2% Significantly improved . 1
77.8% No significant difference 8
0.0% Significantly degraded 0
Total for parameter 9
Percent of
Discharges
0.0%
0.0%
83.3%
16.7%
0.0%
33.3%
66.7%
0.0%
0.0%
11.1%
88.9%
0.0%
Water Quality Results by BMP - Construction of Special Water Handling Facilities
Acidity #
Discharges
Discharge eliminated 5
Significantly improved 6
No significant difference 1 1
Significantly degraded 0
Total for parameter 22
Iron
Discharge eliminated . 7
Significantly improved 4
No significant difference 1 1
Significantly degraded 1
Total for parameter 23
Sulfate
Discharge eliminated 6
Significantly improved 4
No significant difference 12
Significantly degraded 1
Total for parameter 23
Percent of Manganese #
Discharges Discharges
22.7% Discharge eliminated 5
27.3% Significantly improved 4
50.0% No significant difference 8
0.0% Significantly degraded 2
Total for parameter 1 9
Aluminum
30.4% Discharge eliminated 2
17.4% Significantly improved 1
47.8% No significant difference 8
4.3% Significantly degraded 0
Total for parameter 1 1
Flow
26.1% Discharge eliminated 6
1 7.4% Significantly improved 5
52.2% No significant difference 1 0
4.3% Significantly degraded 2
Total for parameter 23
Percent of
Discharges
26.3%
21.1%
42.1%
10.5%
18.2%
9.1%
72.7%
0.0%
26.1%
21 .7%
43.5%
8.7%
Efficiencies ofBMPs
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Coal Remining BMP Guidance Manual
. , ,,,_,, .l... waterQ
Acidity #
Discharges
Discharge eliminated 28
Significantly improved 39
No significant difference 96
Significantly degraded 1
- Total for parameter 164
::;n : :. : , , :: : : Iron
Discharge eliminated 27
Significantly Improved 35
No significant difference 87
Significantly degraded 7
Total for parameter 156
Suifate
Discferge eliminated 28
Significantly improved 33
'No'slghlficanldifference 87
Significantly degraded 21
Total for parameter 169
Water Quality Res
Acidity #
Discharge eliminated 3
Significantly Improved 5
No significant difference 4
Significantly degraded 0
R'1 .fotal'for parameter ' ' "12
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Iron
Discharge eliminated 3
Significantly improved 2
No significant difference 5
Significantly degraded 3
Total for parameter 1 3
Suifate
Discharge eliminated 2
Significantly improved 4
No significant difference 6
Significantly degraded 1
Total for parameter 13
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uality Results by BMP - Daylighting
Percent of Manganese # Percent of
Discharges Discharges Discharges
17.1% Discharge eliminated 21 19.4%
23.8% Significantly improved 23 21.3%
58.5% No significant difference 57 52.8%
0.6% Significantly degraded 7 6.5%
total for parameter ' 108
Aluminum
17.3% Discharge eliminated 17 18.5%
22.4% Significantly improved 13 14.1%
55.8% No significant difference 58 63.0%
4.5% Significantly degraded 4 4.3%
Total for parameter 92
Flow
16.6% Discharge eliminated 28 16.5%
19.5% Significantly improved 35 20.6%
51.5% " No significant difference 96 56".5%
12.4% Significantly degraded 11 6.5%
Total f o r param ete r 170
ults by BMP - Mining of highly alkaline strata
Percent of Manganese " # Percent of
Discharges Discharges Discharges
25.0% Discharge eliminated 0 0.0%
41.7% Significantly improved 2 50.0%
33.3% No significant difference 2 50.6%
0.0% Significantly degraded 0 0.0%
Total for parameter 4
,i, 'II . ' ' , I,;L " ' i!" '', ill 'III Jl' lllii" i ,' 'I'.1 ' II , ,,!|,', i '1 ; T. , ป , ' "I" ' il i'lllllL ' Til' ik ,"",:i
11 ' ',: . ,>,, L II,;*" 'III, II i' ' . I , ..il'llll ' I /' , I,'!,' ",, i '', ", 1; '1 I illlll iir": "Hi .'-li
Aluminum
23.1% Discharge eliminated 0 0.0%
15.4% Significantly improved 0 0.0%
38.5% No significant difference 3 100.0%
23.1% Significantly degraded 0 6.6%
Total for parameter 3
Flow
15.4% Discharge eliminated 2 15.4%
30.8% Significantly improved 6 46.2%
46.2% No significant difference 5 38.5%
7.7% Significantly degraded 0 0.0%
total for parameter 13
: i
,,6-12 _ Efficiencies of BM Ps
.. .. . t .
ItMiiiilii [lil'lll l:l>ll
it,! ::,<:iiiKi,iiiiir nil
!!!,,I;/ 'is, t1:: i,:t .i
IR ii:l;;i! ill /IIU': i,! ,'ij,'!
,;; ' 'M.ii>..'rl Il V-Jf 't..
-------
Coal Remining BMP Guidance Manual
Water Quality Results by BMP - Passive Treatment System Construction
Acidity
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Iron
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Sulfate
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
# Percent of
Discharqes Discharges
0 0.0%
0 0.0%
1 100.0%
0 0.0%
1
1 50.0%
0 0.0%
1 50.0%
0 0.0%
2
0 0.0%
1 50.0%
1 50.0%
0 0.0%
2
Manganese
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Aluminum
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Flow
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Water Quality Results by BMP - Special handling of acid-forming
Acidity
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Iron
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Sulfate
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
# Percent of
Discharqes Discharqes
11 14.1%
17 21.8%
48 61.5%
2 2.6%
78
11 15.7%
15 21.4%
39 55.7%
5 7.1%
70
11 13.8%
15 18.8%
42 52.5%
12 15.0%
80
Manganese
# Percent of
Discharqes Discharqes
1 100.0%
0 0.0%
0 0.0%
0 0.0%
1
0 0.0%
0 0.0%
1 100.0%
0 0.0%
1
0 0.0%
1 50.0%
1 50.0%
0 0.0%
2
material
# Percent of
Discharqes Discharqes
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Aluminum
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Flow
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
12 23.5%
8 15.7%
28 54.9%
3 5.9%
51
6 15.8%
6 15.8%
25 65.8%
1 2.6%
38
11 13.8%
16 20.0%
47 58.8%
6 7.5%
80
Efficiencies ofBMPs
6-13
-------
l! ; 'i ' .,i,'i ,"! I'll i , Jfl !' li'iill'll'' , ' ,; :., in
11 I, i i h-,11111 illlli'Mii , r11'!!,,!! iiifi1 i' , , "'; ;,
I,: J ,' ' , ill-1* , , il i,- , 1 n iiiiii"' ,11 , f, "
"!?!. j ,,i !, "'i.! ,, fcjt, ',,. ' Jf> ; ,:;.*i illilii ;:i ' ; ;"'' -n1'; ii I ",
Coal Remining SSfP Guidance Manual
T
imiijl" ,|i' <|i
1 i;
If1
;: :' .'..> Acidity
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Iron
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Sulfate
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
,, 'l'. ' ' "'liill'il ' '!: Jill ii,' ' "
' i.,1 ' fili ,'ili ; ;
Acidity
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Iron
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Sulfate
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
6-14
Water Quality Results by
# ' Percent of
Discharges | Discharges
30 19.5%
41 26.6%
82 53,2%
1 0.6%
154.
33 24.1%
25 18.2%
72 52.6%
7 5.1%
137
27 17.4%
32 20.6%
81 52.3%
15 9.7%
155
Water Quality Results by B
i : # Percent of
Discharges | Discharges
35 20.1%
46 26.4%
93 53.4%
0 0.0%
174
40 25.3%
29 18.4%
82 51 .9%
7 4.4%
'158
34 19.3%
40 22.7%
85 48.3%
17 9.7%
176
BMP - Surface Regrading
Manganese
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
total lor parameter
Aluminum
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
total for parameter
i
Flow
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
MP - Surface Revegetation
i"" ""i".,; ' < : I'iWi: ,. " ,; . -HI ,-;
Manganese
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Aluminum
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
Flow
Discharge eliminated
Significantly improved
No significant difference
Significantly degraded
Total for parameter
# I Percent of
Discharges (Discharges
21 18.9%
23 20.7%
58 ' ' 52.3%
9 8.1%
"'111
14 16.7%
17 20.2%
'51 "66.7%"'
2 2.4%
'84
26 16.7%
42 26.9%
78 50.0%
10 6.4%
156
,;. ,;,!!!, - . . .,,; i,,;
- # Percent of
Discharges Discharges
26 20.5%
25 19.7%
67 52.8%
9 7.1%
127
17 17.3%
20 20.4%
58 59.2%
3 3.1%
33 18.6%
46 26.0%
88 49.7%
10 5.7%
177
Efficiencies ofBMPs
-------
Coal Remining BMP Guidance Manual
Of the 12 BMPs assessed, only 3 were reported to be used singly, accounting for effects on 8.7
percent (20) of 231 discharges. The BMPs reported as being implemented singly were regrading
(affecting 1 discharge), revegetation (affecting 5 discharges), and daylighting (affecting 14
discharges). However, the possibility that regrading was implemented alone, without
revegetation, is doubtful. The pollution abatement of the remaining discharges was affected by
BMP groups containing up to 6 BMPs. Table 6.2b lists the observed effects of the various BMP
groupings implemented on 231 pre-existing discharges or hydrologic units.
Efficiencies of BMPs
6-15
-------
.Coal Remining BMP Guidance Manual
Table 6.2b: PA Remining Study - Observed Effects of BMP Groupings on Discharges
BMP Group Code
(a) Regrading
,ll"(b)i i JReyegetation
(c) Daylighting
(d) Special Handling
(e) Alkaline Addition < 100 tons/acre
(f) Special Water Handling Facilities
(g) Passive Treatment
(h) Coal Refuse Removal
(i) Biosolids Application
(j) Mining High Alkaline Strata
(k) Allcalme Addition > 100 tons/acre
(I) On-Site Alkaline Redistribution
Ratings Code
4 Eliminated
3 Improved
2 Unchanged
1 Got Worse
- '-' - ; '
BMP Group
C
b
a
c,l
Discharges
Affected
14
5
1
1
Parameter
acidity
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
Rating
1
0
0
1
1
0
2
0
1
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
0
2
9
5
4
5
12
8
3
3
4
2
2
1
0
1
0
0
1
1
1
1
0
0
1
1
3
3
4
4
2
1
3
2
1
1
3
3
3
1
0
0
1
0
0
0
b
0
0
0
0
4
1
3
2
2
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Improved or
Eliminated
!: %
30.8%
: 58.3%
'54.5%
40.0%
14.3%
28.6% -
40.0%
'20.0%
"20.0%
60.0%
!60.0%
60.0%
:LIOO.O%
" 0.0%
0.0%
!1000%
' 0.0%
0.0%
0.0%
0.0%
_
; .
I
0.0%
II
" 0.0%
Got
Worse
%
0.0%
0.0%
9.1%
10.0%
0.0%
14.3%
0.0%
20.0%
0.0%
0.0%
0.0%
20.0%
0.0%
0.0%
100.0%
0.0%
0.0%
0.0%
0.0%
0.0%
_
_
0.0%
0.0%
6-16
Efficiencies ofBMPs
-------
Coal Remining BMP Guidance Manual
BMP Group
c,h
c, e
c,d
b,i
b,c
a,b
Discharges
Affected
1
12
5
1
5
18
Parameter
acidity
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
acidity
iron
manaanese
aluminum
flow
sulfate
acidity
iron
manaanese
aluminum
flow
sulfate
acidity
iron
manaanese
aluminum
flow
sulfate
acidity
iron
manaanese
aluminum
flow
sulfate
1
0
0
0
0
0
0
0
0
0
0
1
0
1
1
1
0
1
3
0
0
0
0
0
0
0
0
0
1
0
0
0
0
2
0
0
1
2
1
1
0
1
1
1
8
8
1
1
8
9
4
3
0
1
4
2
0
0
0
0
0
0
1
1
2
2
1
1
9
6
4
3
6
7
3
0
0
0
0
0
0
3
2
0
0
1
1
0
o
0
0
0
0
1
0
0
0
0
0
2
2
1
0
2
2
2
2
2
2
5
3
4
0
0
0
0
0
0
1
1
0
0
2
2
0
0
0
0
0
0
0
1
1
1
1
1
2
2
2
2
2
2
7
2
3
1
7
7
Improved or
Eliminated
%
0.0%
0.0%
.
0.0%
0.0%
0.0%
33.3%
27.3%
0.0%
0.0%
25.0%
25.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
1 00.0%
100.0%
100.0%
100.0%
100.0%
100.0%
80.0%
80.0%
60.0%
40.0%
80.0%
80.0%
50.0%
40.0%
45.5%
50.0%
66.7%
55.6%
Got
Worse
%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
8.3%
00%
20.0%
25.0%
100.0%
0.0%
20.0%
60.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
200%
0.0%
0.0%
0.0%
0.0%
18.2%
0.0%
0.0%
5.6%
Efficiencies ofBMPs
6-17
-------
Coal R'emining BMP Guidance Manual
BMP Group
c. h. i
c, e, f
c, d k
c. d. i
c, d. e
b d. 1
Discharges
Affected
1
1
1
3
5
1
Parameter
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
1
0
0
0
0
0
0
0
d
0
0
0
0
0
0
1
0
0
0
0
2
0
0
0
0
0
0
0
0
0
2
0
0
0
0
0
0
2
0
1
1
0
1
1
0
0
0
0
0
0
1
1
0
0
1
1
0
1
0
0
1
2
3
3
3
3
3
1
0
0
0
0
0
0
3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
0
0
0
2
1
0
0
0
0
0
0
0
0
0
0
0
0
4
1
0
0
0
0
0
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
2
2
2
0
2
2
1
1
1
0
1
1
Improved or
Eliminated
: %
100.0%
0.0%
0.0%
_
0.0%
0.0%
100.0%
100.0%
100.0%
100.0%
100.0%
' 100.6%
0.0%
: 0.0%
0.0%
'
0.0%
" 0.0%
100.0%
0.0%
_
_
66.7%
33.3%
40.0%
40.0%
40.0%
0.0%
40.0%
40.0%
100.0%
100.0%
100.0%
_
: 100.0%
100.0%
Got
Worse
%
o.b%
o.'o% '
0.0%
_
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
100.0%
_
0.0%
0.0%
0.0%
66.7%
" ,
_
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
40.0%
0.0%
0.0%
0.0%
m
0.0%
0.0%
, j,.
Ui V'ni 11,1
6-18
Efficiencies of BMPs
-------
Coal Remining BMP Guidance Manual
BMP Group
b,d, k
b,d,e
b, c, k
b, c, g
b, c,f
b, c, e
Discharges
Affected
1
' 1
1
1
1
4
Parameter
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
1
0
0
1
0
0
0
2
0
0
1
0
1
1
1
1
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
2
2
1
2
3
3
3
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
1
0
0
0
0
1
0
0
0
4
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
1
1
0
1
1
0
0
0
0
0
0
0
0
0
2
1
1
1
1
1
Improved or
Eliminated
%
100.0%
100.0%
0.0%
.
0.0%
0.0%
0.0%
0.0%
0.0%
_
0.0%
0.0%
100.0%
100.0%
_
.
100.0%
100.0%
.
100.0%
100.0%
_
100.0%
100.0%
0.0%
0.0%
0.0%
100.0%
0.0%
0.0%
50.0%
33.3%
50.0%
33.3%
25.0%
25.0%
Got
Worse
%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
.
0.0%
0.0%
0.0%
0.0%
.
0.0%
0.0%
0.0%
0.0%
.
0.0%
00%
0.0%
0.0%
100.0%
0.0%
100.0%
100.0%
0.0%
0.0%
25.0%
0.0%
0.0%
0.0%
Efficiencies ofBMPs
6-19
-------
I"11'1 ' I I ill ,! /. ;;!:' ''hi
Coal Remining BMP Guidance Manual
'Jill 1!
If1 i | , 1 '' .'I,
6-20
i iu
BMP Group
b, c, d
a, d, k
a. d e
a. c, f
a. c, d
a, b, k
Discharges
Affected
2
1
1
2
1
2
Parameter
aciditv
iron
manganese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
1
0
0
0
0
0
0
1
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
1
1
2
1
1
0
0
0
0
0
0
1
1
1
1
0
1
1
1
0
1
0
0
1
0
0
0
0
0
0
0
0
0
0
o '
0
3
1
1
0
0
1
2
0
0
0
0
0
0
0
0
0
0
0
0
i
1
1
0
2
1
0
0
0
0
0
0
0
0
6
0
1
o' "'
4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
1
0
1
1
1
1
2
2
0
0
1
2
Improved or
Eliminated
%
50.0%
50.0%
0.0%
0.0%
50.0%
100.0%
0.0%
0.0%
0.0%
.
0.0%
0.0%
0.0%
0.0%
0.0%
_
0.0%
0.0%
50.0%
,100.0%
50.0%
.
100.0%
i! 50.0%
100.0%
.
;ioo.o%
100.0%
100.0%
100.0%
100.0%
100.0%
.
!
'"" 'Wo%:
100.0%
Got
Worse
%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
100.0%
100.0%
100.0%
_
100.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
.
0,0%
0.0%
0.0%
.
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
_
0.6%
0.0%
^ ..... iilj ........... iiii ...... 'ji
Efficiencies ofBMPs
^ ....... ll& ......... l,:"i ...... i ........ iaiii ..... fii ..... ift
-------
Coal Remining BMP Guidance Manual
BMP Group
a, b, h
a, b, g
a,b,f
a, b, e
a,b,d
a, b, c
Discharges
Affected
3
1
4
4
4
37
Parameter
acidity
iron
manaanese
aluminum
flow
sulfate
acidity
iron
manaanese
aluminum
flow
sulfate
acidity
iron
manaanese
aluminum
flow
sulfate
acidity
iron
manaanese
aluminum
flow
sulfate
acidity
iron
manaanese
aluminum
flow
sulfate
acidity
iron
manaanese
aluminum
flow
sulfate
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
o
2
1
1
3
3
2
1
1
1
2
2
2
1
1
0
1
1
1
0
0
0
0
1
1
4
3
3
0
3
4
2
2
1
1
2
4
20
22
19
12
18
19
3
2
0
0
0
1
1
0
0
0
0
0
0
3
2
2
0
2
2
0
1
0
0
1
0
2
2
2
2
2
0
10
4
7
7
11
9
4
0
0
0
0
0
0
0
0
0
0
0
0
1
2
2
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
6
9
3
4
5
5
Improved or
Eliminated
%
66.7%
0.0%
0.0%
0.0%
33.3%
33.3%
0.0%
0.0%
.
0.0%
0.0%
0.0%
100.0%
100.0%
1 00.0%
75.0%
75.0%
0.0%
25.0%
0.0%
_
25.0%
0.0%
50.0%
50.0%
66.7%
66.7%
50.0%
0.0%
44.4%
35.1%
33.3%
45.8%
43.2%
38.9%
Got
Worse
%
0.0%
50.0%
50.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
25.0%
.
0.0%
00%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
5.4%
3.3%
4.2%
8.1%
8.3%
Efficiencies ofBMPs
6-21
-------
Coal Remining BMP Guidance Manual
BMP Group
c, e, f, i
c, d, e, f
b, c, d, e
a, c, i, k
a, b, i, k
a. b. e, f
Discharges
Affected
2
1
5
1
2
1
Parameter
aciditv
iron
manganese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
acidity
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
2
0
1
0
0
0
0
0
0
0
0
0
0
5
4
0
0
3
2
1
1
0
0
0
1
0
1
1
0
0
0
1
0
0
0
0
0
3
1
0
0
0
0
0
0
1
1
0
1
1
0
0
0
0
0
1
0
0
0
0
1
0
2
0
0
0
1
1
0
rn.: I ' -
0
b1
0
1
1
4
1
1
0
0
2
2
0
0
0
0
0
0
0
1
0
0
2
2
0
0
0
0
0
0
0
1
1
0
1
1
0
III ซ
0
0
0
0
0
Improved or
Eliminated
; Mi;; %. [, ^
100.0%
50.0%
.
'100.0%
100.0%
_
'100.0%
100.0%
! _ .
100.0%
100.0%
0.0%
' 20.0%
_
_
40.0%
60.0%
I 0.0%
! 0.0%
I
_
100.0%
r
; 0.0%
" w"!fo8M' ""
50.0%
50,0%
_
100.0%
100.0%
0.0%
0.0%
0.0%
: 100.0%
100.0%
Got
Worse
%
0.0%
0.0%
.
.
0.0%
0.0%
0.0%
0.0%
.
0.0%
o"6%
b".b%
0.0%
_
_
0.0%
0.0%
0.0%
0.0%
_
_
0.0%
0.0%
0.0%
ll
0.0%
0.0%
_
0.0%
0.0%
0.0%
100.0%
100.0%
_
0.0%
0.0%
6-22
Efficiencies ofBMPs
-------
Coal Remining BMP Guidance Manual
BMP Group
a, b, d, 1
a, b, d, k
a, b, d, j
a, b, d, h
a,b,d,f
a, b, c, I
Discharges
Affected
3
1
1
3
1
1
Parameter
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
suifate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
o
1
0
0
0
0
0
0
0
2
0
0
0
0
0
0
1
1
1
1
1
1
1
0
0
0
0
0
1
1
2
1
3
3
1
1
0
0
0
1
0
0
0
0
0
0
3
0
0
0
0
1
1
0
0
0
0
0
0
0
1
1
0
1
1
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4
3
1
3
2
2
2
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
1
1
Improved or
Eliminated
%
100.0%
100.0%
100.0%
100.0%
100.0%
100.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
100.0%
100.0%
100.0%
100.0%
66.7%
50.0%
0.0%
50.0%
0.0%
0.0%
0.0%
0.0%
.
.
0.0%
0.0%
100.0%
.
.
100.0%
100.0%
100.0%
Got
Worse
%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
.
.
100.0%
0.0%
0.0%
0.0%
0.0%
0.0%
Efficiencies ofBMPs
6-23
-------
Coal Retaining BMP Guidance Manual
BMP Group
a, b, c, k
a, b, c, j
a, b, c, i
a, b, c, f
a, b, c, e
a, b, c, d
Discharges
Affected
1
1
1
4
14
18
Parameter
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
1
0
0
0
0
0
0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
2
3
0
1
0
1
3
5
2
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
b
0
1
1
1
1
3
3
8
8
7
9
8
7
11
8
4
9
1O
9
3
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
1
2
1
1
0
0
0
3
2
3
1
2
2
7
5
4"
2
K
4
4 ' "
1
1
0
0
1
1
1
0
0
0
0
0
0
1
1
1
b
o
1
2
1
0
1
1
2
2
1
1
2
2
0
2
i! "
1
0
n
0
Improved or
Eliminated
! %
100.0%
! 100.0%
..
_
100.0%
100.0%
100.0%
0.0%
_
_
l! 0.0% !:
1 0.0%
100.0%
100.0%
ioo.o%
100.0%
100.0%
100.0%
75.0%
75.0%
i 66.7%
! 0.0%
25.0%
25.0%
'38.5%
"33.3%
33.3%
'18.2%
"28.6%
28.6%
"38.9%
'43.8%
:55.6%
'"'"!|il6.7% '
' V7 R%
! 22.2%
Got
Worse
%
0.0%
0.0%
_
_
0.0%
0.0%
0.0%
100.0%
_
_
0.0%
100.0%
0.0%
0.0%
0.0%
0.0%
0.0%
65%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
o.d%
0.0%
8.3%
0.0%
14.3%
21 .4%
' 0.6%
6.3%
0.0%
8.3%
1 R 7%
27.8%
6-24
Efficiencies ofBMPs
I Oiti^ I ,;
ilii^^^^^ It..:!!!;:.!....; i
-------
Coal Remining BMP Guidance Manual
BMP Group
a, b, c, e, j
a, b, c, d, f
a, b, c, d, e
a, b, d, e, h, i
Discharges
Affected
3
8
12
1
Parameter
acidity
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manaanese
aluminum
flow
sulfate
aciditv
iron
manganese
aluminum
flow
sulfate
1
0
0
0
0
0
0
0
o
0
0
0
0
0
n
0
0
0
1
0
0
0
0
0
0
2
2
2
0
3
2
2
7
7
7
7
6
7
8
A
4
1
8
6
0
0
1
0
1
0
3
1
0
0
0
1
1
0
0
0
0
1
0
2
9
0
0
2
3
1
1
0
1
0
1
4
0
1
0
0
0
0
1
1
1
1
1
1
2
3
3
2
2
2
0
0
0
0
0
0
Improved or
Eliminated
%
33.3%
33.3%
.
0.0%
33.3%
33.3%
12.5%
12.5%
12.5%
12.5%
25.0%
12.5%
33.3%
ซ fiฐ/_
42.9%
66.7%
33.3%
41.7%
100.0%
100.0%
0.0%
100.0%
0.0%
1000%
Got
Worse
%
0.0%
0.0%
.
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
n n%
0.0%
0.0%
0.0%
8.3%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
Efficiencies ofBMPs
6-25
-------
Coal Remining BMP Guidance Manual
6.3 Predicted Efficiencies
The ratings of BMP effects presented in Table 6.2b were used to predict the effects that
Individual BMPs would have on pollution loadings of acidity, iron, manganese, aluminum and
sulfate and on flow rates of pre-existing discharges.
6.3.1 Statistical Approach
Because the effect of BMPs on pollutant loadings in each discharge were summarized using a
rating on a four point scale (got worse, no difference, improved, eliminated), the effects of the
various BMPs on discharges were assessed statistically using a logit-link logistic regression
jnodel (Agresti, 1990). This model is based on theassumption that the natural logarithm of the
odds of an event (in this case, that a discharge at least improves) is linearly related to certain
predictor variables (in this case, 10-12 BMP variables, each indicating whether a specific BMP
affected a discharge). The model can be used to predict the odds of an event's occurrence (i.e.
the odds of a BMP improving or eliminating a discharge pollution load). In this way, the model
I!
can be used to evaluate the effect of each BMP separately, and make predictions of the likelihood
pf a discharge pollution load improving or being eliminated for a given BMP.
A number of assumptions were made while applying this model in order to predict BMP effects
and determine BMP efficiencies. These assumptions include:
I
"'ป The number of discharges that were observed to be significantly degraded by BMPs or
BMP groups was so low that these discharges could not be used for meaningful statistical
t
analyses. For example, the occurrences of "significantly degraded" in regards to acidity
[
and aluminum loading were infrequent (occurred with acidity in 2 out of 225 discharges
-------
Coal Remining BMP Guidance Manual
and occurred with aluminum in 4 out of 117 discharges). This is illustrative of how
successful remining and the use of appropriate BMPs can be when properly implemented.
It was assumed that both elimination and improvement of discharge pollution loadings
are measures of success and could be combined into a single rating (i.e., "at least
improved").
The ratings of "no significant difference" and "significantly degraded" were not
combined. Rahall permits stipulate that pollution loadings in pre-existing discharges
must at least maintain baseline levels.
The ratings "significantly improved" and "eliminated" were combined and assessed
against "no significant difference." Therefore, the prediction variable had two possible
outcomes (no difference or at least improved) and a logit model for a binary outcome was
used.
Summary data for the effects of passive treatment were only available for one discharge
for acidity, manganese or aluminum. Summary data for alkaline addition greater than 100
tons/acre were only available for one discharge for aluminum. Therefore, passive
treatment was not assessed in regards to acidity, manganese or aluminum, and alkaline
addition greater than 100 tons/acre was not assessed in regards to aluminum.
All discharges or hydrologic units were treated independently regardless of hydrologic
connection or proximity to other discharges. It is probable that ratings for multiple
discharges within the same permit would correlate more highly with each other than
discharges from different permits. However, due to the wide range in numbers of
discharges per permit (from one to ten), and the two-category nature of the outcome
variable, a reliable estimate of this correlation could not be made.
Efficiencies of BMPs
6-27
-------
Coal Retaining BMP Guidance Manual
6.3.2 Statistical Results
Model prediction results for individual BMP efficiencies in regards to acidity, iron, manganese,
aluminum, sulfate, and flow, are reported in Tables 6.3a through 6.3f. Tables 6.3e and 6.3f
present sulfate loadings and flow rate, respectively. As previously stated, sulfate and flow
typically are not regulated, but but can provide insight into the causes of BMP effectiveness or
ineffectiveness. The prediction results are indicated as follows:
Probability: Out of 100 events, how frequently would discharges be improved with
implementation of this BMP(s)
Ratio of Odds: What are the odds of improvement if the BMP(s) is implemented vs. if
the BMP(s) is not implemented (odds are the probability of at least improvement divided
by the probability of no improvement). Due to the low number of discharges made
';' ., r'tlill," hill i:.:, i ;!, .;" ' I, ' TV . ', ' : ; ,;t ''I , >. : Slip I ! /M v .I1.1'1'1 -I'lij,1!", '!!, VI'"" ','< ,;.,",;';
-------
Coal Remining BMP Guidance Manual
situation where no BMPs are implemented. Because no discharges existed that were not affected
by at least one BMP, the intercept was estimated by assessing the effect of the presence of each
BMP individually, and extrapolating to the case where all those effects are absent.
The second column (Probability of at Least Improvement) of Tables 6.3a through 6.3f gives the
model-predicted percentage of discharges that would be improved or eliminated in all discharges
affected by that BMP. Since no data for discharges getting significantly worse were used, the
percentages should be interpreted as the predicted percentage of discharges that would at least
improve, as compared to those that would remain unchanged. The third column (Ratio of Odds)
lists the ratio of odds of at least improvement where the given BMP is used with or without other
BMPs compared with the odds of at least improvement where the BMP is not used. For example,
a ratio of 2.0 indicates that the odds of at least improvement are two times higher when the BMP
is used. Column 4 lists the number of discharges (n) that were affected by the particular BMP in
regards to the parameter being assessed (i.e., acidity, iron, manganese, aluminum, sulfate, or
flow).
Statistical Significance
Because some BMPs affected a small number of discharges, the odds ratios were reviewed for
statistical significance. Column 5 lists the p-values calculated from the Wald Chi-square test for
the statistical significance of odds ratios (i.e., that the corresponding odds ratio in Column 3 was
significantly different from 1.0) tested at the 95 percent significance level (i.e., a = 0.05)
(Agresti, 1990). The value of a denotes the probability of a false positive, or the probability
(based on the Wald test) that the model would determine that a BMP will have a significant
effect on the odds of at least improvement, when in actuality the BMP does not have an effect.
An odds ratio (from Column 3) significantly greater than one is an indication that inclusion of
that BMP would significantly increase the odds of improvement. An odds ratio significantly less
than one is an indication that inclusion of that BMP would significantly decrease the odds of
improvement.
Efficiencies of BMPs
6-29
-------
Coal Remitting BMP Guidance Manual
ii-;1:1". ""Hi" 'lei
The p-values reported in Column 5 give the probability of observing (in a similar data set) an
odds ratio equal to or greater than that in Column 3, if hi truth that BMP does not have an effect
on the pddjjjof at least improvement. If the odds ratio in Column 3 is less than 1.0, the p-value
gives the probability of observing an odds ratio equal to or less than the predicted odds ratio in
Column 3. If the calculated p-value is less than the designated a (0.05), it can be concluded that
Illin'l'" I1 ! jiiilllHllt Hi1 ilrl1 il! : -, , '" ' I,1!'1'" , ',|l II" ', '"' .'"ii!1 ', ' , '! ' I!,, ... ' , , ! I'" hi lilliliilJIIMI, . i '!!!, Ij l<""1'!11 ". ',iilli "
-------
Coal Remining BMP Guidance Manual
conjunction with a BMP group that includes mining of high-alkaline strata than when a BMP
group that includes special handling is used without water handling. Because the odds ratio for a
BMP present in a significant interaction does not apply in situations when the second BMP of the
interaction is present, the test for significant interactions cannot lead to the conclusion that the
BMP is significant in all cases, merely that it is significant when the second BMP is not present.
Efficiencies ofBMPs
6-31
-------
'''ifjjiillliiiliili'liniillllllilr'liirilin1!!1! TWlli'I
i! I!:,:1 TijIJII R'ilffiifl'il
IS
Coa/ Remining BMP Guidance Manual
Table 6.3ar PA Remining Study - Predicted Odds of Acidity Improvement or Elimination
BMP or BMP Group
None (Intercept term)
Regrading
Revegetation
Daylighting
Special Handling
Alkaline Addition
<100 tons/acre
Water Handling
Passive Treatment
Coal Refuse Removal
Biosolids Addition
Mining of Alk. Strata
Alkaline Addition
>100 tons/acre
Alkaline
Redistribution
'Special Handling/
Water Handling
Probability
of at Least
Improvement
37.3
34.7
50.1
37.1
31.0
25.4
71.4
Ratio of Odds with
BMP(s) vs. Odds without
BMP(s)
1.00
0.893
1.684
0.991
0.755
0.570
4.182
Discharges
Affected
(n)
154
174
164
78
65
22
p-value of
Wald test
(at a=0.05)
0.783
0.279 *
0.981
0.387 *
0.098
0.040 *
Passive treatment affected only 1 discharge / discharge was unchanged
57.6
71.5
64.2
56.6
80.9
7.7
2.283
4.216
3.005
2.190
7.127
vs. Spec. Hand.: 0.186
vs. Water Hand.: 0.020
9
6
12
11
6
9
0.285
0.215
0.098 *
0.312
0.083
0.018
* Assessment of significance not meaningful due to presence in significant interaction term
Interaction terms: ' Combined effect is less than expected from combining single effects
2 discharges got worse: These discharges were not used in statistical assessments of improvement or elimination
of acidity. No predictions regarding discharges getting worse were made.
Discharge BMPs Affecting Discharge
1 Daylighting, Special Handling
" i '! ! 2 Regrading, Special Handling, Alkaline Addition >100 tons/acre
6-32
Efficiencies of BMPs
i IHii"1 IBM
'!: IT iiiiili > i,
-------
Coal Remining BMP Guidance Manual
Table 6.3b: PA Remining Study - Predicted Odds of Iron Improvement or Elimination
BMP or BMP Group
None (Intercept term)
Regrading
Revegetation
Daylighting
Special Handling
Alk. Add.<100 tons/ac.
Water Handling
Passive Treatment
Coal Refuse Removal
Biosolids Addition
Mining of Alk. Strata
Alk. Add. >100 tons/ac
Alkaline Redistribution
'Special Handling/
Water Handling
Probability of
at Least
Improvement
40.3
36.0
51.3
37.7
42.1
32.2
73.1
42.6
26.2
62.9
49.7
48.6
61.3
18.3
Ratio of Odds with
BMP(s) vs. Odds without
BMP(s)
1.00
0.831
1.559
0.896
1.075
0.703
4.013
1.010
0.525
2.504
1.463
1.400
2.340
vs. Spec. Hand.: 0.308
vs. Water Hand. :0.083
Discharges
Affected
(ซ)
137
158
156
70
60
23
2
7
6
13
11 .
3
10
p-value of
Wald test
(at a=0.05)
0.657
0.359
0.775
0.833 *
0.311
0.049 *
0.947
0.492
0.348
0.590
0.649
0.505
0.021
* Assessment of significance not meaningful due to presence in significant interaction term
Interaction terms: 'Combined effect is less than expected from combining single effects
11 discharges got worse: These discharges were not used in statistical assessments of improvement or elimination
of iron. No predictions regarding discharges getting worse were made.
Discharge BMPs Affecting Discharge
1 Revegetation
2 Daylighting, Special Handling
3-4 Daylighting, Special Handling, Mining of High Alkaline Strata
5 Regrading, Special Handling, Alkaline Addition >100 tons/acre
6 Regrading, Revegetation, Coal Refuse Removal
7-8 Regrading, Revegetation, Daylighting
9 Regrading, Revegetation, Alkaline Addition <100 tons/acre, Water Handling
10 Regrading, Revegetation, Daylighting, Mining of High Alkaline Strata
11 Regrading, Revegetation, Daylighting, Special Handling
Efficiencies of BMPs
6-33
-------
II 111 III
Coal Remitting BMP Guidance Manual
3!ahlg..&.3.Qa FA StHdy - Predicted Odds of Manganese Improvement or Elimination
BMP or BMP Group
None (Intercept term)
Regrading
Revegetation
Daylighting
Special Handling
Alk. Add.<100 ton/ac
Water Handling
Passive Treatment
Coal Refuse Removal
Biosolids Addition
Mining of Alk. Strata
Alk.Add>100ton/ac
Alkaline Redistribution
"Special Handling/
Water Handling
Probability of
at Least
Improvement
54.0
50.0
44.6
55.1
60.3
42.3
90.4
Ratio of Odds with
BMP(s) vs. Odds without
BMP(s)
1.00
0.850
0.685
1.043
1.290
0.624
8.010
Discharges
Affected
(n)
Ill
127
108
51
39
19
p-value of
Wald test
(at a=.05)
0.717 *
0.493
0.923 *
0.534
0.250
0.024
Passive treatment affected only 1 discharge/discharge was eliminated
2.8
96.1
68.8
6.2
92.6
39.5
0.024
21.150
1.877
0.056
10.597
vs. Special Handling: 0.43
vs. Water Handling: 0.069
6
5
4
6
4
9
0.047
0.060
0.551
0.098
0.130
0.016
* Assessment of significance not meaningful due to presence in significant interaction term
Interaction terms: 'Combined effect is less than expected from combining single effects
14 discharges got worse: These discharges were not used in statistical assessments of improvement or elimination of
manganese. Ho predictions regarding discharges getting worse were made.
Discharges BMPs Affecting Discharge
1 Daylighting
2 Regrading
3 Daylighting, Special Handling
4,5 Regrading, Revegetation
6 Daylighting, Special Handling, Alkaline Addition >100 tons/acre
== r'' 7 Revegetation, Daylighting, Water Handling
8 Revegetation, Daylighting, Alkaline Addition <100 tons/acre
9 Regrading, Special Handling, Alkaline Addition >100 tons/acre
10 Regrading, Revegetation, Coal Refuse Removal
11 Regrading, Revegetation, Alkaline Addition <100 tons/acre
12 Regrading, Revegetation, Daylighting
13 Regrading, Revegetation, Alkaline Addition < 100 tons/acre, Water Handling
14 Regrading, Revegetation, Daylighting, Alkaline Addition <100 tons/acre
6-34
Efficiencies of BMPs
:!: I'"1' ,1,1' I IP 'I'l'lll'/II
-------
Coal Remining BMP Guidance Manual
Table 6.3d: PA Remining Study - Predicted Odds of Aluminum Improvement or
Elimination
BMP or BMP Group
None (Intercept term)
Regrading
Revegetation
Daylighting
Special Handling
Alkaline Addition
<100 tons/acre
Water Handling
Passive Treatment
Coal Refuse Removal
Biosolids Addition
Mining of Alk. Strata
Alkaline Addition
>100 tons/acre
Alkaline Redistribution
Probability of
at Least
Improvement
59.1
61.2
55.0
43.0
47.5
49.9
59.5
Ratio of Odds with
BMP(s) vs. Odds
without BMP(s)
1.00
1.094
0.847
0.522
0.625
0.690
1.017
Discharges
Affected
(n)
84
98
92
38
26
11
p-value of
Wald test
(at ซ=0.05)
0.862
0.784
0.198
0.278
0.446
0.980
Passive treatment affected only 1 discharge/discharge was unchanged
34.0
96.4
26.1
0.356
18.587
0.245
6
3
3
0.257
0.074
0.372
Alkaline addition >100 affected only 1 discharge/discharge was unchanged
93.3
9.711
3
0.139
4 discharges got worse: These discharges were not used in statistical assessments of improvement or elimination of
aluminum. No predictions regarding discharges getting worse were made.
Discharges
1
2
3
4
BMPs Affecting Discharge
Daylighting
Revegetation, Daylighting
Regrading, Revegetation, Daylighting
Regrading, Revegetation, Daylighting, Special Handling
Efficiencies of BMPs
6-35
-------
Coal Remining BMP Guidance Manual
Table (>.3e: FA Remining Study - Predicted Odds of Sulfate Improvement or Elimination
BMP or BMP Group
None (Intercept term)
Regrading
Revegetation
Daylighting
Special Handling
Alk. Add.<100 tons/ac
Water Handling
Passive Treatment
Coal Refuse Removal
Biosolids Addition
Mining of Alk. Strata
Alk. Add>100 tons/ac
Alkaline Redistribution
1 Revegetation/
Alk. Add.<100 tons/ac
2Special Handling/
Alk. Add.<100 tons/ac
Probability
of at Least
Improvement
27.1
12.3
75.1
24.1
10.8
38.9
31.8
17.9
9.0
76.0
65.4
37.0
80.1
44.8
63.4
Ratio of Odds with
BMP(s) vs. Odds without
BMP(s)
1.00
0.377
8.113
0.852
0.326
1.708
1.251
0.585
0.267
8.492
5.081
1.579
10.794
vs. Revegetation: 0.269
vs. Alk. Add.: 1.277
vs. Spec. Hand.: 14.275
vs. Alk. Add.: 2.721
Discharges
Affected
(ซ)
155
176
169
80
67
23
2
9
6
13
11
6
45
26
p-value of
Wald test
(at a=0.05)
0.030
0.002 *
0.678
0.010*
0.457 *
0.660
0.716
0.167
0.106
0.022
0.599
0.041
0.029
0.004
* Assessment of significance not meaningful due to presence in significant interaction term.
Interaction terms: 'Combined effect is less than expected from combining single effects.
JjL _ .j' ' !";:;!!,; ' fit:- ^Combined effect is more than expected from combining single effects
&4 discharges got worse: These discharges were not used in statistical assessments of improvement or elimination of sulfate. No
predictions regarding discharges getting worse were made.
1.'.'. :Discharges BMPs Affecting Discharge
1,2 Daylighting
3,4,5 Daylighting, Special Handling
6,7 Daylighting, Special Handling, Alkaline Addition <100 tons/acre
8 Revegetation
9 Revegetation, Daylighting, Water Handling
10 Regrading, Revegetation
;: 11 Regrading, Revegetation, Special Handling, Alkaline Addition > 100 tons/acre
12-14 Regrading, Revegetation, Daylighting
. 15 Regrading, Revegetation, Daylighting, Mining of High Alkaline Strata
16-18 Regrading, Revegetation, Daylighting, Alkaline Addition <100 tons/acre
i: 19-23 Regrading, Revegetation, Daylighting, Special Handling
24 Regrading, Revegetation, Daylighting, Special Handling, Alk. Add. < 100 tons/acre
6-36
Efficiencies of BMPs
-------
Coal Remining BMP Guidance Manual
Table 6.3f: PA Remining Study - Predicted Odds of Flow Improvement or Elimination
BMP or BMP Group
None (Intercept term)
Regrading
Revegetation
Daylighting
Special Handling
Alk.Add.<100 ton/ac
Water Handling
Passive Treatment
Coal Refuse Removal
Biosolids Addition
Mining of Alk. Strata
Alkaline Addition
>100 tons/acre
Alk. Redistribution
'Revegetation/
Alk.Add.lOOtons/ac
1 Revegetation/
Mining of Alk. Strata
Probability of
at Least
Improvement
19.5
16.4
66.0
13.3
12.7
52.3
21.3
14.9
1.4
80.4
88.7
30.4
66.3
50.7
65.8
Ratio of Odds with BMP(s)
vs. Odds without BMP(s)
1.00
0.807
8.009
0.631
0.601
4.529
1.118
0.721
0.061
16.897
32.367
1.798
8.109
vs. Revegetation: 0.529
vs. Alk. Addition: 0.935
vs. Revegetation: 0.989
vs. Mining Alk.Strata:
0.245
Discharges
Affected
(n)
156
177
170
80
67
23
2
9
6
13
11
6
45
12
p-value of
Wald test
(at a=.05)
0.621
0.005 *
0.212
0.121
0.054 *
0.827
0.821
0.025
0.072
0.002 *
0.489
0.082 *
0.014
0.019
* Assessment of significance not meaningful due to presence in significant interaction term.
Interaction terms: 'Combined effect is less than expected from combining single effects.
13 discharges got worse: These discharges were not used in statistical assessments of improvement or elimination of
sulfate. No predictions regarding discharges getting worse were made.
Discharges BMPs Affecting Discharge
Daylighting, Alkaline Addition < 100 tons/acre
Daylighting, Special Handling
Revegetation, Daylighting, Water Handling
Regrading, Special Handling, Alkaline Addition > 100 tons/acre
Regrading, Revegetation, Special Handling, Water Handling
Regrading, Revegetation, Daylighting
Regrading, Revegetation, Daylighting, Alkaline Addition <100 tons/acre
Regrading, Revegetation, Daylighting, Special Handling
1
2
3
4
5
6,7,8
9,10
11-13
Efficiencies of BMPs
6-37
-------
Coal Remining BMP Guidance Manual
6.3.2.2
BMP Combinations
Selection of BMP combinations that are regularly employed during remining operations allows
for a true determination of the efficiencies, rather than projected efficiencies for BMP
pprnMnations not presently occurring in the real world. BMP groups were selected for evaluation
based on the observed implementation of the combinations in the Pennsylvania Remining Study.
A secondary BMP group selection criterion was that each group affected a minimum of four
discharges that were not significantly degraded. With under four discharges impacted by a BMP
combination, the data subset is too small to allow credible conclusions and predictions based on
the results. This selection of BMP combinations affecting four or more discharges allows study
of the most frequently used combinations, by default.
The BMP groups of: (1) regrading and re vegetation, (2) daylighting, and (3) regrading,
revegetation, and daylighting were employed as control (reference) groups for comparison with
groups containing additional BMPs. These three reference groups were selected for control
because they are implemented as part of remining and occur as stand-alone BMPs. An operation
would not be considered to be a remining operation unless one or more of these BMPs is
conducted or coal refuse reprocessing is performed. These three BMP reference groups are
directly related to the re-affecting of previously mined areas, because regrading and revegetation
aj:e used at abandoned surface-mined lands and daylighting is used for abandoned underground
mines. Coal refuse reprocessing is seldom conducted (affected 9 out of 231 total discharges in
|i
the data set) and therefore was excluded as a control BMP.
:'-; - _" :V;";":i: ; - ; ;; , , ; ! ;-;;; _ ;;; "^- , " ; ; ; ; ; ;;
This BMP group selection precluded the determination of potential efficacy of some BMP groups
that, based on experience, may be highly successful in reducing pollution loads. Some BMPs,
including mining into alkaline strata and alkaline addition (>100 tons per acre), are used
i:
infrequently, but have been shown to be quite successful when implemented.
6-38
Efficiencies of BMPs
..I'll 11 "Hi : ' .'i'!1
-------
Coal Remining BMP Guidance Manual
The observed results were used to compare the three reference groupings to the selected BMP
combinations. Performances of selected BMP combinations were compared to BMP reference
groups using the observed study results (number of discharges eliminated, improved or
unchanged) presented in Table 6.2b. This comparison provides an indication of relative observed
performance, and does not necessarily predict BMP group efficiencies. Each reference group
was compared to only those BMP groups that included the reference group (although groups did
not need to include revegetation when compared to the reference group containing regrading and
revegetation). Again, only those BMP groups that affected at least four non-worsening
discharges were used in the calculation.
Observed Percent Improved: For each group, the percent of discharges that at least improved
was determined by dividing the number of discharges that were improved or eliminated, by the
number mat were improved, eliminated, or did not significantly change (significantly degraded
discharges were not included in the calculations because of their small number) and multiplying
by 100.
Observed Odds of Improvement: For each group, the odds of at least improvement were
calculated as the number of improved or eliminated discharges affected, divided by the number
of discharges that did not significantly change.
Observed Odds Ratio Compared to Reference: The odds ratio for a given group represents
the odds of at least improvement for that group, divided by the odds of at least improvement for
the reference group.
Percent Improved minus Reference Percent Improved: The last column in Tables 6.3g
through 6.3x gives the difference between the percentage of discharges affected by the BMP
group that at least improved minus the percentage of discharges at least improved by the
reference group.
Efficiencies ofBMPs
6-39
-------
"CoalRemining BMP Guidance Manual
For example, in Table 6.3m, Daylighting (reference group) improved or eliminated acidity
' ' : | |
loading in 4 discharges, and did not change acidity loading in 9 other discharges. Therefore, the
Observed percentage of discharges that at least improved is 4/13 x 100 = 30.8 percent, and the
- i
observed odds of at least improvement is 4/9 = 0.444. The group of Daylighting and Alkaline
Addition T; i ,. , iTtiin, , i in,, , - ,, IT i, ,i>, r , ' a v
that at least improved is 4/12 x 100 = 33.3 percent, and the observed odds of at least
improvement was 4/8 = 0.500. The odds ratio comparing Daylighting and Alkaline Addition
<100 tons/acre to the reference group (Daylighting) is 0.500/0.444 = 1.125. According to the
observed data, the odds of at least improvement is 1.125 times higher when Daylighting and
Alkaline Addition <100 tons/acre were used compared to when Daylighting was used alone.
For some BMP groups (i.e., Regrading, Revegetation, and Water Handling for acidity and iron),
all discharges affected were improved or eliminated This yields infinite odds, since the number
of discharges improved or eliminated is divided by 6. Therefore, an odds ratio cannot be
calculated for these groups.
Efficiencies ofBMPs
-------
Coal Remining BMP Guidance Manual
Table 6.3g: Analysis of Discrete Groups based on Observed Acidity Results Using
Regrading and Revegetation as Reference Group
BMP Group
Regrading, Revegetation
(Reference)
Regrading, Revegetation,
Daylighting
Regrading, Revegetation,
Special Handling
Regrading, Revegetation,
Alkaline Addition <100
Regrading, Revegetation,
Water Handling
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water
Handling
Number
of
Discharges
Affected
18
36
4
4
4
18
13
12
8
Number of
Discharges
Improved or
Eliminated
9
16
2
0
4
7
5
4
1
Number of
Discharges
Unchanged
9
20
2
4
0
11
8
8
7
Observed
Percent
Improved
50.0
44.4
50.0
0.0
100.0
38.9
38.5
33.3
12.5
Observed
Odds Ratio
compared
to
Reference
0.800
1.000
0.0
00 *
0.636
0.625
-
0.500
0.143
Percent
Improved
minus
Reference
Percent
Improved
...
-5.6
0.0
-50.0
50.0
-11.1
-11.5
-16.7
-37.5
Observed Percentage Improvement: On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
Observed Odds of Improvement:
Ratio of Odds:
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Regrading & Revegetation) is implemented
: Because all discharges for this grouping were improved, the odds of improvement would be 4 divided by 0.
Therefore, the odds ratio is infinite.
Efficiencies ofBMPs
6-41
-------
Coal Remining BMP Guidance Manual
Table 6.3h: Analysis of Discrete Groups based on Observed Iron Results Using
Regrading and Revegetation as Reference Group
BMP Group
Regrading, Revegetation
(Reference)
Regrading, Revegetation,
Daylighting
Regrading, Revegetation,
Special Handling
Regrading, Revegetation,
Alkaline Addition <100
Regrading, Revegetation,
Water Handling
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <1 00
Regrading, Revegetation,
Daylighting, Special
Handling, Water Handling
Number of
Discharges
Affected
12
37
4
4
4
16
12
9
8
Number of
Discharges
Improved
or
Eliminated
6
13
2
1
4
7
4
5
1
Number of
Discharges
Unchanged
6
22
2
3
0
8
8
4
7
Observed
Percent
Improved
50.0
37.1
50.0
25.0
100.0
46.7
33.3
55.6
12.5
Observed
Odds Ratio
compared
to
Reference
0.591
1.000
0.333
00 *
0.875
0.500
"
1.250
0.143
Percent
Improved
minus
Reference
Percent
Improved
-12.9
0.0
-25.0
50.0
3.3
-16.7
5.6
-37.5
JDbserved Percentage Improvement: On a scale of 0-100, how frequently were discharges improved with
l|1""" '"" "' " " Implementation of this BMP grouping
Observed Odds of Improvement:
Ratio of Odds:
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Regrading & Revegetation) is implemented
* Because all discharges for this grouping were improved, the odds of improvement would be 5 divided by 0.
Therefore, the odds ratio is infinite.
6-42
Efficiencies ofBMPs
-------
Coal Remining BMP Guidance Manual
Table 6.3i: Analysis of Discrete Groups based on Observed Manganese Results Using
Regrading and Revegetation as Reference Group
BMP Group
Regrading, Revegetation
(Reference)
Regrading, Revegetation,
Daylighting
Regrading, Revegetation,
Alkaline Addition <100
Regrading, Revegetation,
Water Handling
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition < 100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water Handling
Number of
Discharges
Affected
11
30
4
4
9
12
7
8
Number of
Discharges
Improved
or
Eliminated
5
10
0
4
5
4
3
1
Number of
Discharges
Unchanged
4
19
3
0
4
7
4
7
Observed
Percent
Improved
55.6
34.5
0.0
100.0
55.6
36.4
42.9
12.5
Observed
Odds Ratio
compared
to
Reference
0.421
0.0
00 *
1.000
0.457
' 0.600
0.114
Percent
Improved
minus
Reference
Percent
Improved
-21.1
-55.6
44.4
-0.0
-19.2
-12.7
-43.1
Observed Percentage Improvement: On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
Observed Odds of Improvement:
Ratio of Odds:
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Regrading & Revegetation) is implemented
* Because all discharges for this grouping were improved, the odds of improvement would be 5 divided by 0.
Therefore, the odds ratio is infinite.
Efficiencies ofBMPs
6-43
-------
Coal Re'mining BMP Guidance Manual
Table 6.3j: Analysis of Discrete Groups based on Observed Aluminum Results Using
tion as Reference Group
BMP Group
Regrading, Revegetation
(Reference)
Regrading, Revegetation,
Daylighting
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water Handling
Number of
Discharges
Affected
6
24
12
11
8
Number of
Discharges
Improved
or
Eliminated
3
11
2
2
1
Number of
Discharges
Unchanged
3
12
9
9
7
Observed
Percent
Improved
50.0
47.8
18.2
18.2
12.5
Observed
Odds Ratio
compared
to
Reference
0.917
0.222
0.222
0.143
Percent
Improved
minus
Reference
Percent
Improved
-2.2
-31.8
-31.8
-37.5
"If / "'I,I ,ป,,' ' '.ill '
i ; , 1:1,1 I'll!,; i '!! ,
Observed Percentage Improvement:
i i ill i
111 i IN 11 ii
Observed Odds of Improvement:
Ratio of Odds:
On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
,""' '" Y i 'Ml in '" Ji>ttii
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Regrading & Revegetation) is implemented
1 i'':|l ' i;i' ' ""! I, i :f , '' ' !, ;
-------
Coal Remining BMP Guidance Manual
Table 6.3k: Analysis of Discrete Groups based on Observed Sulfate Results Using
Regrading and Revegetation as Reference Group
BMP Group
Regrading, Revegetation
(Reference)
Regrading, Revegetation,
Daylighting
Regrading, Revegetation,
Special Handling
Regrading, Revegetation,
Alkaline Addition <100
Regrading, Revegetation,
Water Handling
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water
Handling
Number
of
Discharges
Affected
18
36
4
4
4
18
14
12
8
Number of
Discharges
Improved or
Eliminated
10
14
0
0
3
4
4
5
1
Number of
Discharges
Unchanged
7
19
4
4
1
9
7
6
7
Observed
Percent
Improved
58.8
42.4
0.0
0.0
75.0
30.8
36.4
45.5
12.5
Observed
Odds Ratio
compared
to
Reference
...
0.516
0.000
0.000
2.099
0.311
0.400
-
0.583
0.100
Percent
Improved
minus
Reference
Percent
Improved
-16.4
-58.8
-58.8
16.2
-28.0
-22.4
-13.3
-46.3
Observed Percentage Improvement:
Observed Odds of Improvement:
Ratio of Odds:
On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Regrading & Revegetation) is implemented
Efficiencies ofBMPs
6-45
-------
Coal Remining BMP Guidance Manual
ilHiiiC [ "'f.'il : !,:,
Table 6.31: Analysis of Discrete Groups based on Observed Flow Results Using
Regrading and Revegetation as Reference Group
BMP Group
Regrading, Revegetation
(Reference)
Regrading, Revegetation,
Daylighting
Regrading, Revegetation,
Special Handling
Regrading, Revegetation,
Alkaline Addition <100
Regrading, Revegetation,
Water Handling
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <1 00
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <1 00
Regrading, Revegetation,
Daylighting, Special
Handling, Water
Handling
Number
of
Discharges
Affected
18
37
4
4
4
18
14
12
8
Number of
Discharges
Improved or
Eliminated
12
16
2
1
3
5
4
4
2
Number of
Discharges
Unchanged
6
18
2
3
1
10
8
8
6
Observed
Percent
Improved
66.7
47.1
50.0
25.0
75.0
33.3
33.3
33.3
25.0
Observed
Odds Ratio
compared
to
Reference
0.444
0.500
0.167
1.500
0.250
0.250
~
0.250
0.167
Percent
Improved
minus
Reference
Percent
Improved
-19.6
-16.7
-41.7
8.3
-33.3
-33.3
-33.3
-41.7
Observed Percentage Improvement:
Observed Odds of improvement:
ii] : t i';!,:l" ซซ ritlliiJi ,'l. ,-'. ', " , !"!>!
Ratio of Odds:
On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
I
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Regrading & Revegetation) is implemented
6-46
Efficiencies ofBMPs
-------
Coal Remining BMP Guidance Manual
Table 6.3m: Analysis of Discrete Groups based on Observed Acidity Results Using
Daylighting as Reference Group
BMP Group
Daylighting
(Reference)
Daylighting, Alkaline
Addition < 100
Regrading, Revegetation,
Daylighting
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition<100
Regrading, Revegetation,
Daylighting, Special
Handling, Water Handling
Number of
Discharges
Affected
13
12
36
5
18
13
12
8
Number of
Discharges
Improved
or
Eliminated
4
4
16
2
7
5
4
1
Number of
Discharges
Unchanged
9
8
20
3
11
8
8
7
Observed
Percent
Improved
30.8
33.3
44.4
40.0
38.9
3.8.5
33.3
12.5
Observed
Odds
Ratio
compared
to
Reference
1.125
1.800
1.500
1.432
1.406
1.125
0.321
Percent
Improved
minus
Reference
Percent
Improved
-2.5
13.6
9.2
8.1
7.7
2.5
-18.3
Observed Percentage Improvement: On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
Observed Odds of Improvement:
Ratio of Odds:
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Daylighting) is implemented
* Because all discharges for this grouping were improved, the odds of improvement would be 4 divided by 0.
Therefore, the odds ratio is infinite.
Efficiencies ofBMPs
6-47
-------
Coal Reminmg BMP Guidance Manual
, !" , M,! i !"
i IV ' "iii' ; ซii;
Mi"1 I ' ', I1',!,,"
'liiS f. '> '
Table 6.3n: Analysis of Discrete Groups based on Observed Iron Results Using
;s.-:. iii'iliiai., Daylighting as Reference Group
,;;;;;;
:""
'' illlllllll'lllll
Ill !!,i
1 'ป'
.it
iiiiu
iili'!,;
li;"?!
in
iii;
inn
Iff
!
::,:::,
'
1"1"
nun inn
BMP Group
Daylighting
(Reference)
Daylighting, Alkaline
Addition <100
Regrading,
Revegetation,
Daylighting
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading,
Revegetation,
Daylighting, Special
Handling
Regrading,
Rcvegetation,
Daylighting, Alkaline
Addition <1 00
Regrading,
Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading,
Revegetation,
Daylighting, Special
Handling, Water
Handling
Number of
Discharges
Affected
12
11
37
5
16
12
9
8
Number of
Discharges
Improved or
Eliminated
7
3
13
2
7
4
5
1
Number of
Discharges
Unchanged
5
8
22
3
8
8
4
7
Observed
Percent
Improved
58.3
27.3
37.1
40.0
46.7
33.3
55.6
12.5
Observed
Odds Ratio
compared
to
Reference
0.268
0.422
0.476
0.625
_0.357
0.893
0.102
Percent
Improved
minus
Reference
Percent
Improved
-31.0
-21.2
-18.3
-11.6
-25.0
-2.7
-45.8
Observed Percentage Improvement:
Observed Odds of Improvement:
Ratio of Odds:
JriiL ill, II
On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
"i,i .'*
Number improved or eliminated divided by number with no significant
difference
i -
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Daylighting) is implemented
6-48
Efficiencies ofBMPs
llll! !jl|i!,i>;\iMji||J'ii!||ii'n Ili'J" , illlil H,n,'illi '
-------
Coal Remining BMP Guidance Manual
Table 6.3o: Analysis of Discrete Groups based on Observed Manganese Results Using
Daylighting as Reference Group
BMP Group
Daylighting
(Reference)
Regrading, Revegetation,
Daylighting
Daylighting, Special
Handling, Alkaline
Addition <1 00
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <1 00
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <1 00
Regrading, Revegetation,
Daylighting, Special
Handling, Water
Handling
Number of
Discharges
Affected
11
30
5
9
12
7
8
Number of
Discharges
Improved
or
Eliminated
6
10
2
5
4
3
1
Number of
Discharges
Unchanged
4
19
3
4
7
4
7
Observed
Percent
Improved
60.0
34.5
40.0
55.6
36.4
42.9
12.5
Observed
Odds
Ratio
compared
to
Reference
0.351
0.444
0.833
0.381
0.500
0.095
Percent
Improved
minus
Reference
Percent
Improved
-25.5
-20.0
-4.4
-23.6
-17.1
-47.5
Observed Percentage Improvement:
Observed Odds of Improvement:
Ratio of Odds:
On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Daylighting) is implemented
Efficiencies ofBMPs
6-49
-------
Coal Retaining BMP Guidance Manual
iiri'11 rri1., -, "f:
I1*!" :-:!.i i; .'if
l
'
Table 6.3p: Analysis of Discrete Groups based on Observed Aluminum Results Using
Daylighting as Reference Group
I1
I!
BMP Group
Daylighting
(Reference)
Regrading,
Revegetation,
Daylighting
Regrading,
Revegetation,
Daylighting, Special
Handling
Regrading,
Revegetation,
Daylighting, Alkaline
Addition <100
Regrading,
Revegetation,
Daylighting, Special
Handling, Water
Handling
Number of
Discharges
Affected
10
24
12
11
8
Number of
Discharges
Improved or
Eliminated
4
11
2
2
1
Number of
Discharges
Unchanged
5
12
9
9
7
Observed
Percent
Improved
44.4
47.8
18.2
18.2
12.5
Observed
Odds Ratio
compared
to
Reference
1.146
0.278
0.278
0.179
_
Percent
Improved
minus
Reference
Percent
Improved
3.4
-26.2
-26.2
-31.9
Observed Percentage Improvement: On a scale of 0-100, how frequently were discharges improved with
I!fifjii 1SSM'''?" "'ill' !: " !;>f "ii1 '':l: '! I -i;' implementation of this BMP grouping
i
' n'"ป 'ill '"Ill if"!" III! II I II I I |l I III ,>, I. ,11 I
Number improved or eliminated divided by number with no significant
i, ."'difference ,'',',.',. '. '_ 1, ,'.,' I "'" " "".,.'!..', "" ' ",I"',,',
r
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Daylighting) is implemented
Observed Odds of Improvement:
Ratio of Odds:
it I1
,1 !';' I
Hill11 '!
"i,;/1.!:1' f I III 'III'1'.1'! ,'ii I'll I
" ra ii ^iiii ji n;i;rB"i
6-50
Efficiencies of BMPs
-------
Coal Remining BMP Guidance Manual
Table <6.3q: Analysis of Discrete Groups based on Observed Sulfate Results Using
Daylighting as Reference Group
BMP Group
Daylighting
(Reference)
Daylighting, Alkaline
Addition < 100
Regrading, Revegetation,
Daylighting
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water Handling
Number of
Discharges
Affected
14
12
36
18
14
12
8
Number of
Discharges
Improved
or
Eliminated
4
3
14
4
4
5
1
Number of
Discharges
Unchanged
8
9
19
9
7
6
7
Observed
Percent
Improved
33.3
25.0
42.4
30.8
36.4
45.5
12.5
Observed
Odds
Ratio
compared
to
Reference
...
0.666
0.516
0.889
1.143
1.667
0.286
Percent
Improved
minus
Reference
Percent
Improved
-8.3
9.1
-2.5
3.1
12.2
-20.8
Observed Percentage Improvement:
Observed Odds of Improvement:
Ratio of Odds:
On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Daylighting) is implemented
Efficiencies ofBMPs
6-51
-------
Coal Remining BMP Guidance Manual
(I IK ill ill li
|i
Table 6.3r: Analysis of Discrete Groups based on Observed Flow Results Using
Daylighting as Reference Group
III II ( IB i
I:1
BMP Group
Daylighting
(Reference)
Daylighting, Alkaline
Addition < 100
Regrading, Revegetation,
Daylighting
Daylighting, Special
Handling, Alkaline
Addition <1 00
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <1 00
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water Handling
Number of
Discharges
Affected
14
12
37
5
18
14
12
8
Number of
Discharges
Improved
or
Eliminated
2
3
16
2
5
4
4
2
Number of
Discharges
Unchanged
12
9
18
3
10
8
8
6
Observed
Percent
Improved
14.3
25.0
47.1
40.0
33.3
33.3
33.3
25.0
Observed
Odds
Ratio
compared
to
Reference
2.000
5.333
4.000
3.000
3.000
3.000
2.000
Percent
Improved
minus
Reference
Percent
Improved
10.7
32.8
25.7
19.0
19.0
19.0
10.7
Observed Fercentage Improvement:
Observed Odds of Improvement:
ii T i 11 ( ililliilll i i n in i "!
On a scale of O-lOO, how frequently were discharges improved with
implementation of this BMP grouping
Number improved or eliminated divided by number with no significant
difference '
Ratio of Odds:
What are the odds of improvement if BMP grouping is implemented
vs. if reference!'grouping (Daylighting) is implemented
I !i;;::; \m ^""m,^L rW> IAIT.WI ^
I '-I ilk ill illl'llli'i
I ^llIKi
1101 BM, ,i:..^ijl , liti
,!! ..... Ill
f, ' s" 'if i -1'"' ,; ,','. I1'*
i;; 't'1 i" " '.-. '.a 'i1, - ,j"1.. i
'W.-. i^ '! mm
W:,m\
'"
". iliill'i J i
1 .I'''"" i'1'I, I, '"i , ill n'; ''iiilVii 'i ;, ii1
.:.' ' '.!.ill I : .'. iii:,,;i '''*t;..... : I'l'II ;,V;i
'I'lIBi''"!! ':!: :"":'4 I
I!;!!! ii, 5 ,-i:
6-52
Efficiencies ofBMPs
-------
Coal Remining BMP Guidance Manual
Table 6.3s: Analysis of Discrete Groups based on Observed Acidity Results Using
Regrading, Revegetation, and Daylighting as Reference Group
BMP Group
Regrading, Revegetation,
Daylighting (Reference)
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water
Handling
Number of
Discharges
Affected
36
18
13
12
8
Number of
Discharges
Improved
or
Eliminated
16
7
5
4
1
Number of
Discharges
Unchanged
20
11
8
8
7
Observed
Percent
Improved
44.4
38.9
38.5
33.3
12.5
Observed
Odds
Ratio
compared
to
Reference
0.795
0.781
0.625
0.179
-
Percent
Improved
minus
Reference
Percent
Improved
-5.5
-5.9
-11.1
-31.9
Observed Percentage Improvement:
Observed Odds of Improvement:
Ratio of Odds:
On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Regrading, Revegetation & Daylighting) is
implemented
Efficiencies of BMPs
6-53
-------
Coal Reminwg BfrfP Guidance Manual
III
Jill'"* :!'Mf!'1' IIILU!
"llili" I jilt ' I. 1 "'
K! 'n I'"!' ; Ot;,:
i
; ..... ^ ..... ill ....... 1
. .....
" I II 'ill
i i ..... ! ....... J .............. to; ..... i: ...... ..A \yfrb .......... b
.
Table 6.3t: Analysis of Discrete Groups based on Observed Iron Results Using
Regrading, Revegetation, and Daylighting as Reference Group
iii'!
BMP Group
Regrading, Revegetation,
Daylighting (Reference)
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <1 00
Regrading, Revegetation,
Daylighting, Special
Handling, Water
Handling
Number of
Discharges
Affected
37
16
12
9
8
Number of
Discharges
Improved
or
Eliminated
13
7
4
5
1
Number of
Discharges
Unchanged
22
8
8
4
7
Observed
Percent
Improved
37.1
46.7
33.3
55.6
12.5
Observed
Odds
Ratio
compared
to
Reference
1.481
0.846
2.115
0.242
Percent
Improved
minus
Reference
Percent
Improved
9.6
-3.8
18.5
-24.6
1 i i11
i i
I'M , ,, |, ,,
fthiff'.K,
mm 'ti:
.Pf1!; li;,-.fl ,"
"vM Ji''' ' ' "' I1!!1 'I1',,
i*"1' !' 'if 1 iJ'i' i:i'i"
ijfj'iliil. I11' 'IF' I : '"
will1 ,i'l ",',i, ,, i: li'11' ,
;ซ;,! (,' i I'1;!! ^ I' S
P'f'iH'i : I!!'"1,!,
!' ""'li' ' " Illl^l
'iisii '.Si: ' W
HE'ti ''ป .I'll i
S"l|iii i Jl: ,ฑ11! :'
illii i' Pi'il 11' ; ; Jlllii'!
Observed Percentage Improvement:
1 '<!".' i: fit, 'iiiaii iiiiiiii' %i - ' , ; ., -I ,,, ,, I-
1 " . 'iJj./'.r.'.LijW. 1|ji!i'!||lll ';,! = ; " '-; ., i j* :,;" ; ป
Observed Odds of Improvement:
"/"I'RatioofOdds:""
i iiiiiin,: vi i i,'1'!,!!:'!!' (fii , ,; LI iiisiij^ ./oiii,1 i,,1.'1 P i,: ' :', ; i U1 . \
rf1 ,.' ';'; -V .tปi iii ''! ' "!/'; ::"' : n," ".
ii, ,
i '
in
Ilir :
" {'( ' H 1
f' 1!' ' |l |H
:, ' itn, i ' i III i '
l'"i. 111 111
in ' , in i
1" Ill i
iiMiiii i
' :&54
On a scale of 0-100, how frequently were discharges improved with
''!; implementation of tWs BMP 'grouping
Number improved or eliminated divided by number with no sig
difference . , ., .,..
:iviV ufv,.:!;*;,:,1!, !%";':, i1-.1;!.!!;; ;;|||;;'';;t':; ||| :'^ .,-|j!,',^v ': :.
What are the pdds of improvement if BMP grouping is impleme
vs. if reference grouping (Regrading, Revegetation & Daylightii
implemented
", ' i in i ; ',i.
i,,;: I,, ii ' ' '
ป i ' " 1 ii III i -
1 .' in '
II i ' '
>"'"' ' ,",
nificant
nted
ig),is
'" '':".;,' , ''('iflllPI II!JI1'',S' '';JB
''' r,,, i'"' l"i'li,l|l|!i' , " '.V "'' "'
Hi ' 'IW ,, .i'llliillVIL1
.'iiil'i'i ซ < i illi1 , nylm ,r '' i!!;
i,!"!''"' ' 'SSIIP ,f" , ''.\
/:; ''-iti/Ali,' "ii;1',': ''}
' "' !i" if'iii" 'iiiii'i'i' :,:';
";:sM,.:^:.i^!, *,
Efficiencies ofBMPs
-------
Coal Remining BMP Guidance Manual
Table 6.3u: Analysis of Discrete Groups based on Observed Manganese Results Using
Regrading, Revegetation and Daylighting as a Reference Group
BMP Group
Regrading, Revegetation,
Daylighting (Reference)
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water .
Handling
Number of
Discharges
Affected
30
9
12
7
8
Number of
Discharges
Improved
or
Eliminated
10
5
4
3
1
Number of
Discharges
Unchanged
19
4
7
4
7
Observed
Percent
Improved
34.5
55.6
36.4
42.9
12.5
Observed
Odds
Ratio
compared
to
Reference
...
2.376
1.086
1.426
0.272
-
Percent
Improved
minus
Reference
Percent
Improved
...
21.1
1.9
8.4
-22.0
Observed Percentage Improvement:
Observed Odds of Improvement:
Ratio of Odds:
On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
Number improved or eliminated divided by number with no significant
difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Regrading, Revegetation & Daylighting) is
implemented
Efficiencies ofBMPs
6-55
-------
Coal Remining BMP Guidance Manual
Table 6.3v: Analysis of Discrete Groups based on Observed Aluminum Results Using
Regrading, Revegetation and Daylighting as Reference Group
BMP Group
Regrading, Revegetation,
Daylighting (Reference)
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water
Handling
Number of
Discharges
Affected
24
12
11
8
Number of
Discharges
Improved
or
Eliminated
11
2
2
1
Number of
Discharges
Unchanged
12
9
9
7
Observed
Percent
Improved
47.8
18.2
18.2
12.5
Observed
Odds Ratio
compared
to
Reference
0.242
0.242
0.156
Percent
Improved
minus
Reference
Percent
Improved
-29.6
-29.6
-35.3
Observed Percentage Improvement:
III I i ' ,ii In 111 "111 i % i ,-
Observed Odds of Improvement:
Ratio of Odds:
On a scale of 0-100, how frequently were discharges improved with
, i liij" nlin Ill ill I'!1' ' ','1' |l" I I i "'I, i'Ml ' ''li'IMI '"' 'ii iJlf n ,i,'ป ' ,.i, r , i ii,
implementation of this BMP grouping
i::,' i", IN' I. . I 'iii I..1"-! ",''!' * '"' V,,' ., ||i" .(, i"',, i ," ''"Ii .'.: ..'
Number improved or eliminated divided by number with no significant
difference
Ii
What are the odds of improvement if BMP grouping is implemented
ys. if reference grouping (Regrading, Revegetation & Daylighting) is
implemented
"6-56
Efficiencies ofBMPs
-------
Coal Remining BMP Guidance Manual
Table 6.3w: Analysis of Discrete Groups based on Observed Sulfate Results Using
Regrading, Revegetation, and Daylighting as Reference Group
BMP Group
Regrading, Revegetation,
Daylighting (Reference)
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water
Handling
Number of
Discharges
Affected
36
18
14
12
8
Number of
Discharges
Improved
or
Eliminated
14
4
4
5
1
Number of
Discharges
Unchanged
19
9
7
6
7
Observed
Percent
Improved
42.4
30.8
36.4
45.5
12.5
Observed
Odds
Ratio
compared
to
Reference
0.603
0.775
1.131
0.194
_
Percent
Improved
minus
Reference
Percent
Improved
-11.6
-6.0
3.1
-29.9
Observed Percentage Improvement:
Observed Odds of Improvement:
Ratio of Odds:
On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
Number improved or eliminated divided by number with no
significant difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Regrading, Revegetation & Daylighting) is
implemented
Efficiencies ofBMPs
6-57
-------
..... ! iiiiiKiT" ...... ip111' ....... ft 'Q ' ' T w " r ' hi INM! " ........ : ii'W!!! IMI i ซ' IPHI :i ..... "i ....... ! ...... " ' !: ...... OF < i ..... 'wniH' ui ...... if*" t IPP inn 1 1 1 n i i i i n nil in 1 1 i in 1 1 1 i n il i n i
n 1 1 1 1 1 n 1 1 in ipi w. iii'ini'iinlniii n flui11'! ซ ' i ..... m I
Coal Remining BMP Guidance Manual
is mu?
i i1'1'!,,:''!!!1 ' !'," I i1 Ik. !'; .
'i I' "'Hi1 j"
VIP1 <<| 'liil, ซ!,
wr! i, .,|i:|!!;l!1 'if ill:
111 1 111'
:;Table 6.3x:;i ^^ijallysis^pf Discrete Groups based on Observed Flow Results Using
Regrading, Revegetation, and Daylighting as Reference Group
,
!'
Ilii
11
lllniiF:i!:l: ;
INI
i
i!;:"i ,;
:iiiiiii?i:i
1
BMP Group
Regrading, Revegetation,
Daylighting (Reference)
Regrading, Revegetation,
Daylighting, Special
Handling
Regrading, Revegetation,
Daylighting, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Alkaline
Addition <100
Regrading, Revegetation,
Daylighting, Special
Handling, Water
Handling
Number of
Discharges
Affected
37
18
14
12
8
Number of
Discharges
Improved
or
Eliminated
16
5
4
4
2
Number of
Discharges
Unchanged
18
10
8
8
6
Observed
Percent
Improved
47.1
33.3
33.3
33.3
25.0
Observed
Odds
Ratio
compared
to
Reference
0.563
0.563
0.563
0.375
Percent
Improved
minus
Reference
Percent
Improved
-13.8
-13.8
-13.8
-22.1
Observed Percentage Improvement:
Observed Odds of Improvement:
Ratio of Odds:
Ml I I II I III I I II (I I 111 II II I I II II III I III III
On a scale of 0-100, how frequently were discharges improved with
implementation of this BMP grouping
Number improved or eliminated divided by number with no
significant difference
What are the odds of improvement if BMP grouping is implemented
vs. if reference grouping (Regrading, Revegetation & Daylighting) is
implemented
" I I Ll !'' Tlili ''" Ml! il,!:!"'" !""
j! "i, ."'I-; nniiiiiir ,nr jiiiiAi11'!
III I1 ill
' ll'l'-il,;;,
5-58
. , ,.,. , Efficiencies of BMPs
.\ ,1 '"ty:! .". .'
i "'liliili 1 cJtJ ! ii:1' :. .!:l ((Hull!1 .JjiUi'i tllllLi 1'Iliili, illlrllllllllB111 ": lllll'lillt i"'l ;,i! dm f I.IL . III! : ': i;::'! ii'l' , i ill ,: -i'i' i, ...... Ill,, Aiil- ..... ,::!':> iliij!"','.!,! IHi'iifl ..... Ii. '", ui; '. I'lilliiiii' ill, .il ..... i ,1.1.1 nil".
nil..'...; ' .111(11 .^..i-'iiaillll1: 'liil!li!i:i. .: .'I'i'llil
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Coal Remining BMP Guidance Manual
6.4 Discussion
6.4.1 Observed Results
The combinations of BMPs affecting the most discharges at the completed Pennsylvania
remining sites in order of decreasing frequency of occurrence are as follows:
Group #
1
2
3
Daylighting, Regrading, Revegetation
Regrading, Revegetation
Daylighting, Regrading, Revegetation, Special
Materials Handling
Daylighting, Regrading, Revegetation, Special
Materials Handling, Alkaline Addition (<100
tons/acre)
Daylighting, Regrading, Revegetation, Alkaline
Addition (<100 tons/acre)
Daylighting, Alkaline Addition (<100 tons
CaCO3 equivalent/acre)
Daylighting, Regrading, Revegetation, Special
Materials Handling, Special Water Handling
Facilities
Discharges Affected
37
18
18
12
14
12
Efficiencies of BMPs
6-59
-------
Coal Remining BMP Guidance Manual
Acidity Loading
Only three BMPs (regrading, revegetation, and daylighting) were reported to be used singly at the
Pennsylvania study remining sites (Table 6.2b). Of these BMPs, only daylighting impacted
Scidity loading in a significant number of discharges (13). Daylighting alone significantly
improved 30.8 percent of the discharges for acidity loading with no discharges significantly
i-i i if!; . jijir::, ,1.. ' ,;,.; 1*.' fjim'. ^iiii >'. , "1 c:,ii''1 .'i:;, ".\ *;'fc .n'.'^Kij1 "'.'' Si I11;" ':.\i iปis;fi 1 "ป ,.;i; t,, .? :& ; '; ' ii" >ป;i;i,S': Ii-";.
'iJ, degraded. Revegetation used singly significantly improved acidity loading in 40 percent of 5
'' i'iii, n,,ll; "" !' IIP? ii1 aiiiii" 'i ,i iirai'iili!1;,!' jJilK/!i! IHIIII '.A Ji'ff'il ,"': liT;i;:,,:; !!,,,' ill ''',: ' "" ,i i I1:"" "'I1'!"'1! ' M i T '""I1 '''111 T: , Blllii :'.i,1! illf'ซ;,"!'.", II1 aunt . W1L II;11, / I? i ,i"'' . !'"ป''!!', "I': ii f1'?: S "M' ft "''Wail!'1,! nJIKilii' '!''
discharges affected with the remainder unchanged. Regrading used singly affected one discharge
i,!?i \.;.::,-i|fi.i .:iJ!" jiLJIs ;i.;;~im am;iIiiiJE! ;i rv.*wiCTij- >;'*>' ? :'i';:: ^iS'VJ:f<' i',: :^''.' i1'***:' ^ iiii'-* .Kifar; SMfiipii>-,;;'" 'i t^ini1^', ปi w i ' 'ill in I
TOich was shown to be significantly improved. However, it is doubtful that regrading was used
without corresponding revegetation.
The seveg.mcjst common BMP groups (listed previously) were highly successful in not degrading
liilu: Lliii *'" :< III I I II 11 I III II III III ill III I I I II I I II I !, i !/ >'' II I II III I I I I I I 111 I I II I |l I I I I I III III 111 III I
the djscharges in terms of acidity loadings. All of the discharges affected by these BMP groups
were either significantly improved or unchanged (Figure 6 4a) with improvement ranging from
1,2,5 to 50 percent of the discharges depending on BMP group. No discharges were significantly
degraded. The most successful BMP combination was regrading and revegetation (#2), followed
i i ii MI ii in i nil i i i in n i ii n i i i in in n 11 i i 111 11 i i ii n i iiiiinn mi in
by daylighting, regrading, and revegetation (#1), and daylighting, regrading, revegetation, and
I alkaline addition (#5). BMP group #2 significantly improved 50 percent of the discharges and
had no significant effect on 50 percent of the discharges. Over 44 percent of the discharges were
improved under BMP group #1 with the remainder unchanged. The success of these BMP
' ii
combinations (#1 and #2) in decreasing acidity loading may be due to the fact that these BMP
, , jj ;
groups are generally used for remining operations that are environmentally uncomplicated and do
ii
not require elaborate BMP plans to effect improvement. Additionally, these BMPs greatly impact
I
, the ampunt olf water moving through the reclaimed site and, to a lesser extent, effect the water
Duality. This may be an indication that flow-reducing BMPs may be more effective in reducing
loads than those that work primarily geochemically. This determination is supported by Smith
i
(1988) and Hawkins (1995) who both observed flow to be the predominant determinant of
j :,,i N
pollution loadings (see Section 1.2, Figure 2.la).
; j 'SiJlliii, ii'l! II,
I i i.-tilfl''!!!!,)!!11!!
I ป';!!
d- .i.ii'illl!", i I'll1/ !'
111 III II1111111 111
Efficiencies of BMPs
11 rff i iii"; ' mi1 iihi'"
IK1!*1 '* ' illllii'linlli'Uliiii'iiliii'Hf, Ml
.iillisJ'Si M.1,1',1,,; ,iliiilll I1'1
-------
Coal Remining BMP Guidance Manual
Figure 6.4a: Impacts of BMP Combinations on Acidity Loading
100
80
20
0
Acidity Load
18 17
JL2_
I I I I I I LJ
345
BMP Group #
HH Better or Eliminated
f\. 1 Unchanged
* No discharges were made worse.
Iron Loading
As previously stated, only three BMPs (regrading, revegetation, and daylighting) were reported to
be used singly at the Pennsylvania study remining sites and of these BMPs, only daylighting
impacted a significant number of discharges (12) for iron loadings. Daylighting singly improved
more than half (58 percent) of the discharges for iron loading and had no effect on the remaining
42 percent. No discharges were significantly degraded. Revegetation alone significantly
improved 20 percent of discharges (1 discharge), significantly degraded 20 percent of the
discharges and did not affect the remaining discharges. Regrading alone was shown to be used
for one discharge which was unchanged. However, as previously stated, it is doubtful that
regrading was used without corresponding revegetation.
Efficiencies of BMPs
6-61
-------
Coal Remining BMP Guidance Manual
Ill' I!1!1]1!::1;SB1 ' >
I
The seven BMP combinations quite successfully left most of the discharges improved or
unchanged in terms of the iron load. The two most successful BMP combinations for discharge
iron load improvement were daylighting, regrading, revegetation, special materials handling, and
alkaline addition (#4) which improved 55.6 percent of the discharges and regrading, revegetation,
and alkaline addition (#8) which improved 50 percent of the discharges. The remaining
discharges affected by those two BMP groups were unchanged. Implementation of two other
BMP groups (daylighting, regrading, and revegetation (#1) and daylighting, regrading,
i!iipi''ซ
'JP'iiliii fli' :.(:' .l&Ofl, loadings (failures). The failure rates were 5.4 and 6.7 percent, respectively. However, the
I''-''lit, 1 I'll I"1'I"V , 1" 1 iff i 'I illiillnl:"' ,4"' ' < it I! I ซnSiiiiiM11, i iiimwiniiiiii MIIIB .hiiu - '".<., ' i nnii: Tฅii.ii:.,:,n n Vi,' ,, l;,,i.|llii,, i>. "in1; ,i!i iป i, . ' 'in PiiiiJ" ,.. r > smi1'.!11' I'lii'nNir'vr1 ",* II.VF 11*11111 HIII,.I m i, vi, i i,,, I,,,Iii! Ii!!1!1!:' !illi:i!.ir 'ti, iff, , fl?!!'.' iiliB'HIII 'Jl Si,!1'. iiiSl" , '"IB" (HI I' * I""";'1-1" '! 1 fiitl'iil'ilil!1;' "JS HlJE i'111: ill,! I'-i'Sii'i''!1!' li'l'.'-*' >. llliS" I""1! "i SMKS
jJliMkaline a jjc/l'l'lili'.'!!"!
improvement. This situation can occur in cases where a large amount of acidic.material is
it 'i1: ''"I!.'Ul .' IB,', ,'0!"!"" ill!1! I
encountered during daylighting and naturally occurring alkaline material was not present in the
overburden. The amount of alkaline addition may have been insufficient to offset the acidity
production.
IE '<
III III
II III
i" i ili'ii i,,,in |i, iliiwi , ' Ei:'!: l
II II
III,,*;,,:!,, "i I, ' I : , ;:,!". Hill I''
IV. 4;,I: : 1
6-62
'ill J11
111 III
Efficiencies ofBMPs
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Coal Remining BMP Guidance Manual
Figure 6.4b: Impacts of BMP Combinations on Iron Loading
Iron Load
16 9 12 11
0
345
BMP Group #
Better or Eliminated
Unchanged
Worse
Efficiencies ofBMPs
6-63
-------
Coa.l Rgtnining BMP Guidance Manual
il'lllil" I SI"!'!.ซ iii til!
Iliiiiliilk -IB!,, ii'l I'k, li
Manganese Loading
;:n!,' I"!;,;) i,' !)! I' -
mm lii
II!!1!'f R ,ii'Hi5'
mm
JIEiu'l1' il' hi,'!'"!"< ' I' bill lilil'l'
I Of the, three BMiPs ..(regradiri gj revegetation",' and daylighting)" used singly at "the Pennsylvania
'ESttidy: remmiiig1sites, only daylighting impacted manganese loading in a significant number of
lii!11"1! i, "l,1 ni'lli"..!'!"';!;! iiiiilillt'.' IBIIIIII ri'i'i,, i : "!'."" ii,1" "I"in1!ill J, i: "" I .i" jii I':" ซ "1|1" I1 i1 ""ii ,;:":; i;'Hi '", 1 '(JH>>*1^ 1'!!" 'ii't'TBIil' IIUM' , liS.li Jiltiill'iS, ,, H",'i(, < iS'J*" i iiiillilli):';!
pl'ljll |!"::,,,, ' 'I 1,11'i " i" Ifl'lllilllllili1' i liiiillllli"1,1;1!!:!!1:,!' ',1, l,i, I'1"1'"! ,i i',11':'"L fil i I" i, "I'iil"1 ,'ir,l, i 'i,,l " i; 'ill I::'! ,:!,,:, .'* nj'";1' il ,: OTH I*":, 1 ,,ซ'',''," 'ijlire IF,ป ""I1 I'I'ln'l " !'I'll l,1'1'''!!',,!^ AIII"' "I1"'!!' * II*,,,"llillll1 IK , 111 .''",' ,,*,, 'T i,"llllllllli,I,
discharges (11). Daylighting singly improved 54.5 percent of the discharges for manganese
11',!';" 1?ii,;:,i?:!.;*ซ -' m>m ;:> si;\ ;>w m it -. ii.fi1 ^ mm. s SMI M ^vmm.am1'tit a, i if,iy>.* turn .-wi i . ./. <.m
,. ,....
loading with 9.1 percent (one discharge) significantly degraded. Revegetation significantly
improved one (20 percent) of five discharges and did not affect the remaining discharges.
''liSli.i^i ^MfJjBBj;.'!'.W
-------
Coal Remining BMP Guidance Manual
Figure 6.4c: Impacts of BMP Combinations on Manganese Loading
N = 30
Manganese Load
11 9 7 12
100
0
345
BMP Group #
Better or Eliminated
| Unchanged
HTT1 Worse
Aluminum Loading
Of the three BMPs (regrading, revegetation, and daylighting) reported to be used singly at the
Pennsylvania study renaming permits, only daylighting impacted a significant number of
discharges (10) for aluminum loadings. Daylighting implemented alone significantly improved
40 percent of the affected discharges for aluminum loading and significantly degraded 10 percent
(one discharge). Revegetation significantly improved 60 percent of the five affected discharges
and had no effect on the remaining two discharges. Regrading implemented alone affected one
discharge which was shown to be significantly improved.
The most successful BMP group in improving the aluminum loads was daylighting, regrading,
revegetation, special materials handling, and alkaline addition (#4) with 66.7 percent of the
Efficiencies of BMPs 6-65
-------
Coal R'eminjng BMP Guidance Manual
discharges exhibiting significant improvement. This was the highest improvement rate exhibited
by any of the BMP groups for any of the contaminants, although this group affected only 3
discharges in terms of aluminum loading. BMP groups of daylighting, regrading, and
revegetation (#1) and regrading and revegetation (#2) were the next most successful in improving
the aluminum loadings with 45.8 and 50 percent improvement, respectively.
Figure 6.3d: Impacts of BMP Combinations on Aluminum Loading
'
1'IMMill,!!1 I1'1 IP:,:"1 llfil"11'1'!1"! , rl'MUiV'ii; ''JIM111,,:,,-: ,
BMP Group #
Better or Eliminated
Unchanged
ITU Worse
Sulfate Loading
As previously stated, sulfate loading is not a regulated effluent parameter, but is included herein
i
to permit a clearer analysis of the effectiveness of BMPs to geochemically reduce the acidity,
iron, manganese, and aluminum loadings. Of the three BMPs (regrading, revegetation, and
daylighting) reported to be used singly at the Pennsylvania study remining sites, only daylighting
i
impacted sulfate loading in a significant number of discharges (14). Daylighting singly improved
I
28.6 percent of the discharges for sulfate loading with 14.3 percent (two discharges) significantly
i
f
6-66 Efficiencies of BMPs
-------
Coal Remining BMP Guidance Manual
degraded. Revegetation significantly improved three (60 percent) of five discharges, did not
affect one discharge, and significantly degraded one discharge. Implementation of regrading
affected one discharge which was improved.
The most successful BMP group in improving sulfate loading was regrading and revegetation
(#2) with 55.6 percent. The next two most successful BMP combinations were daylighting,
regrading, revegetation, special materials handling, alkaline addition < 100 tons/acre (#4) and
daylighting, regrading, and revegetation (#1) exhibiting improvements of 41.7 and 38.9 percent,
respectively. The presence of regrading and revegetation in the three most successful groups
indicates that simply reclaiming an abandoned site may greatly decrease acid production.
Figure 6.4e: Impacts of BMP Combinations on Sulfate Loading
N = 36
0
18
Sulfate Load
18 12 14
12
345
BMP Group #
^| Better or Eliminated
|~\J Unchanged
Worse
Efficiencies ofBMPs
6-67
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Coal Remitting BMP Guidance Manual
Flow Rate
As previously stated, flow rate is not a regulated effluent parameter, but is included herein to
l|ii I I In 11 I 11 III i i i in l in l iiiiiiiii i i i n nil1. ; ,i ii !;MHI 't>i,:i< *rii'; 'i,1, r. !ซ; '.'* JCJCB,' -ama :'. ...fwufi li*.':'.:^'.*.'^'**!*;* e i i i iiiiiii 11
permit a clearer analysis of the effectiveness of BMPs that work to physically reduce the
pollution loadings. Of the three BMPs (regrading, revegetation, and daylighting) used singly at
the Pennsylvania study remining sites, only daylighting impacted flow rate in a significant
number of discharges (14). Daylighting singly improved (decreased or eliminated flow) 28.6
percent of the discharges, with none of the discharges significantly increasing in flow.
Reyegetation significantly improved three (60 percent) of five discharges and effected no change
of the remaining discharges. Implementation of regrading affected one discharge which was
.; r ; unchanged.
,.; B: ;'.!" i llgj! ''I;! ': '] I 1| !f:.Si a: ;|;; If 'if &. if '; f; <,,,": , 'i ", i v.. .,;;,':,;,,!,;!;;.>;; .-1||:; ; \ I,,1, i;.;-1,, ^ K.. II |tiK";;.:? ii; ^., ^f^ :T; ,:;]:'; i lปi :r Jiiill l| ^
The roost successful BMP group in improving flow rate was regrading and revegetation (#2) with
66.7 percent, followed by daylighting, regrading, and revegetation (#1) and daylighting,
regrading, revegetation, special materials handling, alkaline addition < 100 tons/acre (#4)
Exhibiting improvements of 43.2 and 33.3 percent, respectively. As with sulfate, the presence of
o Hi ,.' |i, {,:.? ' giii"! | ;;i: .;' 'pi ."f '! " fiiiiinniiri1: '||I! ,i iiiyii 11 II:,IIIM l: :iv ^i;' ^< MI : IIIIIIH^^ in ;;;' .MIJ ififliK, ,i 'S : "is, .1:,' iซii W: i-* i 'iiiiiiiii! ill1. .1 Mihiii'n 'rpiii". I'1 ri 11: i ,i:"i:;'; l wi l ซ' ' : .'mi1 , j L; ff ; iiiiiiiii; ' K'!i ii"
Degrading and revegetation in both these groups, indicates that simply reclaiming a site will
'" B:;, ;; t lilj.!!1';, [,-: Itiir t !!Si ^ jmt':< ' lihli: i iซ.B;::! ,1 "IS f ":': :i I' ซn|ป I >i ''i' v iV i ;.ซ"* j I !'ปi ซ ;J| i ['.s - it tilliii;1 B"l *ซ;'.;i[ Willj lii'"* '.I' IK 11' > >!.. ' j_;:i !! .t *; ; i , ,, i;; ^ ,;' ' j i" i. ป,-(: jll (f
reduce infiltration into the spoil, which ultimately reduces the outflow.
6-68
Efficiencies of BMPs
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Coal Remining BMP Guidance Manual
Figure 6.4f: Impacts of BMP Combinations on Flow Rate
= 37
20
0
Flow Rate
18 12
14
12
Mill
2345
. BMP Group #
HI Better or Eliminated
I >| Unchanged
Worse
6.4.2 Predicted Results
The data obtained from the Pennsylvania study remining sites were statistically analyzed using
the methodology described in Section 6.3.1. These analyses, applied to single BMPs, determined
the predicted percentage of discharges that would be improved, the odds that a discharge would
be improved, and the odds of improvement over doing nothing at all in terms of BMPs. The
results of these analyses are listed in Tables 6.3a through 6.3d (BMPs implemented alone).
Tables 6.3e and 6.3f are the same analyses conducted for sulfate loadings and flow rate to allow
for an in depth determination of the possible impacts (physical or geochemical) of specific BMPs
and BMP combinations.
Efficiencies of BMPs
6-69
-------
l||l|ll| 111| yi |l||l m i 1111(11 " Jl'SIPII,!1!1! IlliOliri! Mill ;ii!ปi!H I,!"* -I fti" .MS . { MS,/ , "" inf.'!
Cogl Remming BMP Guidance Manual
(ii'iiiiiiia:, ;M :>*. MIBJWH, .: n '-
6.4.2.1
BMPs Implemented Alone
in nun i , n n in n nil iiininn n
Acidity Loading
The predicted probabilities of improvement for all of the single-use BMPs (Revegetation,
Regrading, and Daylighting) range from 27.4 to 50. 1 percent. The remaining BMPs were not
Implemented alone, and therefore, do not have associated observed results. However, the
Statistical analyses Cah provide some insight 'mj-o' mejr efficiency" Alkaline redistribution (80.9
jperceh'tj' ari'3 ..... ^g^ds addition "(7 1 .5 percent) exhibit "the ..... Kigliest ..... predicted" probabilities" of
m\m Eii
i ait wiii p in:
|;|l|;!i:: &
taprovement of acidity loading of all of the BMPs followed by special water handling (7 1 .4
- i i, llii I, ..... i:",]1!4, ...... i ....... 1} ..... ; ( ..... m- i lit 'ill K"S.M "i;;i ....... i> ;IL t; >i : n. . ;o ....... a-" w.:" m *;>. i..; ........ ii ............ "? ms w w wai ,m mas? f a ^
percent), mining alkaline strata (64.2 percent) and coal refuse removal (57.6 percent). It is
.ซ , ' !: , t,' l "'/ m ...... %m i ....... iCiS/ :.: 1 1 ..... :; 1 1? ...... :if / : ........ t .f-.^JiV.*' vi mmm,iiaaw'A: i* ' p; vi ^m^rn'rer':, m ;,ซ i ..... i ........ ',!
interesting to note that alkaline addition of < 100 tons per acre yielded the lowest predicted
Improvement probability of 25.4 percent, while half of the four highest predicted percentages
; j ...... IlllPt- :" ..... fL'ii'i.iiitii: ...... jipie^^i'iiiiiiii > lit' T'Sf.E- .' ...... an us ...... ;. :* a 'ft TI- ...... V.IM.., i1.' > -; [ > rw, ....... rv.tt ......... ifMnai: 'i"ซ ..... '*j'i.L;*J ......... <'1">L ...... *" .",>! ..... '" ........ f> jj ........... . ป 'ป
-:':t ' fjlso deal with i increasing the amount of alkaline material in the backfill. The results may indicate
:;r ; ...... tihattiie, ,ง13211111 ...... olalka|ine material, added (< 100 tons per acre) was too low. Brady and others
f jd, ; ;: _ tlritlSCiiilWI!! illllllE^ {Illllillli] i !A!R::[ !:!"" ! ', 'Iflii1' 9:S ' , r:''!-; ' ., i :',( ...... ttlf1 :ฃ!"' tn "l!: ..... ii il!!i ..... . >:":.~::::1li !. I1 ...... '.I'Mii!11!!,1.1:!.!)11":!!.. J'iii ... * ;A,. ' ,: &:i:illlllllllllll!l!ll||iiilil,i:::.l!ll.||l!ii:i ' ซ Hiป'j ' IP1', il " iV'iiriiiiiiii'Mi'jiigiiiiiiii "ซป HWMHWI fK .mi.1 Hi iiniiiiiiiiJi'jMiIii'iii' ,.n?i.in , ป ...... IM .1;,, win ..... A i " . ..... i. ..... r ..m, JKiiHiniwiiiii'iiiiiiiiiiiiiiii
affected additionally by regrading, revegetation and daylightmg. The failure of special handling
..... 11 * '* - ..... '' *ป ;i
11 1 III I ' I i ';'" f : ;i( ":' ; I :i !
',,ซI| i|| ' i1, jfPj ,, ' *
Hill; Jin I jl 1 1'Mll i \.
, f \,i , ;:l,, : '' " ft ,
' '
[''fiii11:!1!'11'!!11 U'lii1!;,,!,;,1 iii
i isiiii'ii , ,1' " ....... "ftl. : ;
..... I'll 'k.yt^ f. r ',:"! . i;;'"! i,
, * ; . , : u S ' MMrft :lj il,.1'!:!1 V j 1 '>' A Ki I'1" ,
' "' ...... "'""If1 !!:.'!!.''" !"_"":. " '
" inilni 1 1 , i' ; I , iiililL;: ฃ J.T
'
6-70
Efficiencies of BMPs
-------
Coal Remining BMP Guidance Manual
may be because it is frequently employed where a substantial amount of acid-forming materials is
present, perhaps too much to be offset by any single BMP or group of BMPs.
Iron Loading
Predicted probabilities of improvement in iron loading for all of the single-use BMPs range from
36.0 to 51.3 percent. Special water handling facilities (73.1 percent) and biosolids addition (62.9
percent) exhibit the highest predicted improvement percentages followed by alkaline
redistribution (61.3 percent), revegetation (51.3 percent) and mining of alkaline strata (49.7
percent). The lowest predicted probability of improvement is coal refuse removal (26.2 percent).
The relatively low number of discharges affected (7) may bring into question the usefulness of
this prediction value. In addition, the low predicted discharge improvement may be due to a
delayed response in regards to water quality, compared with other BMPs. Refuse is typically
acid-producing and when removed, fresh refuse is exposed to weathering or flushing of existing
weathered products. It may take more time than the limited monitoring periods available to see
improvements in some water quality parameters.
The significant interaction between special handling and water handling indicates that the
positive effect of water handling on the odds of at least improvement is greatly diminished when
special handling is also present. This can be best explained by comparing the observed results for
water handling with and without special handling (see table 6.2b). When water handling and
special handling both affect a discharge, the result is at least improvement 20 percent (2 out of 10
discharges) of the time. However, when water handling but not special handling affect a
discharge, the result is at least improvement 75 percent (9 out of 12 discharges). It is worth
noting that these two BMPs never affect a discharge without being combined with other BMPs.
Eight of the ten discharges affected by both water handling and special handling were also
affected by regrading, revegetation and daylighting.
Efficiencies of BMPs
6-71
-------
Coal Remining BMP Guidance Manual
Manganese Loading
.,,,,.
!' ', I1
Predicted probabilities of discharge improvement for single-use BMPs range from 44.6 to 54.0
percent. Alkaline material redistribution (92.6 percent) and biosolids application (96.1 "percent)"
exhibit the highest predicted improvement, followed by water handling (90.4 percent), mining
alkaline strata (68.8 percent) and special handling (60.3 percent). The lowest probabilities of
improvement were predicted for coal refuse removal (2.8 percent) and alkaline addition >106
^'""::: ^"," riQp'peTacre (6.2 percent). However, these BMPs each affected 6 discharges and the strength of
the prediction is weak. In addition, an improvement in manganese loading in discharges affected
;;.I,;,;,,',, ': .. i j,ycoaj"rQ^Q fe"hiovai may be"delayed as explained in regards to"iron loading.
i':'' "lSfhe significMt'Inter'action'between special"" handling "and' water handling indicates that the
positive"effect of water handling on the odds of at least improvement is greatly diminished when
Special handling is also present. This can be best explained by comparing the observed results for
f' :".,'|",j: iซ" "flpiiSii I'll: HSwtfjiflii illป/o ft:;, ;Jซ m* wisi>;:":^M*B^ ^fr^iii iMti :fm'fmAitKi*& :M;5.jf iiป m
ater Dandling with and without special handling (see table 6.2b). When water handling and
special handling both affect a discharge, the result is at least improvement 22 percent (2 out of 9
discharges) of the time. However, when water handling but not special handling affect a
discharge, the result is at least improvement 88 percent (7 out of 8 discharges) of the time. It is
illiilll'l11'"" liti' ' ml ,,>Ilil!' .I'lMii!;l%!i!ii;if IIIIH^^ PU ,'iat;' r>i;' ucar f: i.<* .:"il!"ii iw11 -"fvi-ai!iiiiii,'!*'1' lifi^i^iiiiiiiii//'!':*!*^^^ nis!11.'.lan.;:::!:1:,.-'\;t,-t
-------
Coal Remining BMP Guidance Manual
predictions are for coal refuse removal (34.0 percent) and mining of high-alkaline strata (26.1
percent). However, these BMPs impacted 6 and 3 discharges respectively, and the strength of the
prediction is questionable. In addition, an improvement in aluminum loading in discharges
affected by coal refuse removal may be delayed as explained in regards to iron and manganese
loading.
Sulfate Loading
Predicted probabilities of discharge improvement for single-use BMPs range from 12.3 to 75.1
percent. Alkaline material redistribution (80.1 percent) and biosolids application (76.0 percent)
exhibit the highest predicted improvement of all of the BMPs, followed by mining alkaline strata
(65.4 percent). The lowest probabilities of improvement were predicted for coal refuse removal
(9.0 percent) and special handling (10.8 percent).
Flow Rate
Predicted probabilities of discharge improvement for single-use BMPs range from 19.5 to 66.0
percent. Mining of alkaline strata (88.7 percent), biosolids addition (80.4 percent), and alkaline
redistribution (66.3 percent) exhibit the highest predicted improvement of all of the BMPs,
followed by alkaline addition < 100 tons per acre with 52.3 percent. The lowest probabilities of
improvement were predicted for coal refuse removal (1.4 percent) and special handling (12.7
percent).
6.4.2.2
BMP Groups
The term "remining" implies that mining will be occurring on an area that has been previously
mined. Specifically, for the sake of this manual, it also implies that the area was mined prior to
implementation of SMCRA (1977) and modern reclamation standards. There are four basic
types of abandoned mine lands that are remined: (1) sites that were previously surface mined, (2)
sites that were previously underground mined, (3) sites that were previously surface mined and
Efficiencies of BMPs 6-73
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Coal Remitting BMP Guidance Manual
Underground mined, and (4) sites that had coal refuse deposited on the surface. These areas
cannot be reaffected or remined jyithout implementation of some minimal BMPs. Table 6.4a
shows the type of previous mining and the associated minimal BMP(s).
Table 6.4a: Types of Mining and Minimal BMPs
1
4:
!!'
T;
Tyjpe of Previous Mining
Surface Mining
Underground Mining
Surface and Underground Mining
Refuse Disposal
Minimal Best Management Practices
Regrading, Revegetation
Daylighting
Regrading, Revegetation and Daylighting
Refuse Removal, Regrading, Revegetation
K *.*)'wiK'.'
,.. iv'^";|:>'';|!1a'V1.,j' :,';:: !'''! V ! Hi KJr'?:[!!
irij, 'f,', !!!i '. |l!ii!B>., iซt fK: || jj ji,', ,;! "it "
apvra s '
"Of the discharges affected by remining, 156 were affected by regrading, 170 by daylighting and
ป'5rlly 9 by;coal refuseremoval. There were alsoia large: number of discharges that were affected
m
iilปu
by both regrading and daylighting. Nearly all discharges affected by regrading were also affected
111! ' 1": I i; ..... !;i^^^^^^^ Jill: : %",. ..... i-;M-XW:&.'ฃ*. ....... , ; if :, [ ....... i" :.! ...... 4SM ! ^ ::"v: i': fi 'I'lftSW II ...... SfiSS 'U ..... 'U/rfliWy ~>M :; ;; i!! Wli-i , i ; ' t ..... 1 --m^ ...... iBT
by revegetation. The group of regrading and revegetation and the group of daylighting occurred
ง1 i f ; $!V ..... ! JK'OT ' 1P;ป:;! J'ffl ...... S" Ml . ' ' i '. Uฐ ' i? .......... :'" ..... [* TOTS : ' , ' 1 ..... 1 ^1 W^-WT. '-. J'lii Ml ...... W3aป^ ซ ..... f : ft WlW
enbugh times that it was possible to compare the effectiveness of these minimum BMPs against
.....
1 .Hi M! ป', ' , ! ii," ,,,,|, .iiri'iiiii, '.M :,i
li ill', ": j|, i
lit ii,,1,,*,,: i i ,f','
the minimum BMPs plus other select BMPs (Tables 6.3g through 6.3r). Likewise, the group of
regrading and revegetation combined with daylighting, together, affected enough discharges for
"^inular evaluation ฃrงble_6.3s through 6.3x). These minimum BMP combinations were
rbqjn@ipงr5d against the minimum combination plus select other BMPs. The BMP groups were
i'lk'l I!" IMIIIW 111!', 'ill!:! <>:<.! ""J'l""!!! IC!iM.'";< U! f';!"':,;,' ' i- Xltill1!1:1'Jlllll.' ii-iilllili1 Of.ill'ill i/l'liWifilli.ilil HWr'.'KWIi: >* "VilifBil I! 1 rHIX
'f1!,!!:!1!
ll
d based on their haying affected at least:
IHII! ailllllllllllii:':; ", piiHlllHX '"p'tllW * I', :"IIH|i ';, 'i,l"" / ";> ,1!'i, iiM'I'Wi1*;! I1' ,i" , '' J! 'i. ...... ii'M'I'Wi'ilC I1' ,i" , '' <||L '"I" I1,' ' ' 'L W*:' ~, t; MS * i; ;W -.''.,J ;: -, it ilWI" ,;i!;I*'
:' .llMllil ifti;'ffiiiiib-Ih iiiitlS'Is 'i'liiiuliA':, il,!1! i'.'ipm : , ','i:;i n It,,;,, < , 'i,V'i ^ii:',;,;)!!,; , Jttiii'itpii|iv!< ii |
.!t4l":;
I!!'- "Mill! ! ill'!!!
: ';i,i:;, *i '' ijiiift: {'jiiiiiE iBiiiiii1',, iiiii '",??, i";1;,!,:1': isis; , i.,,:; I' i' ,i ;'''' si-si:! i" i;": "i(i ' i *,. i i iiiiiiE' iiiiiis i-at ' iiiiiiiH iiSi'i*,* ,1 iii \. i it! :, !",!; A :\ >ป,, \ tv- :i *' i', ' "; >' i.
Jnfortunately some BMPs that had a high rate of success (i.e., alkaline redistribution, mining of
i^ikalihe'"sti^a"aiad"aikaline addition at application rates greater than 100 tons per acre, Table
11IIIU IK"!! Hill! I" iiiiiiiiiiii,: Hill i",;,!,! ;,i!'"ป" i: (-a :-s ii mm , f A'fr: I v,\* ,p: = :>:... BBJS^TW u, i1!-- inซปปB>iM,t.i H'linivn .71 ซ! - I'D'"!1 l; ,i,: '.M; * i s1
i1 '4, :i iilllli' ''Illil',:1'1]1,:!1!)
f^ noฃBeDevaluated,because: they affected too few discharges.
' ' i1
il^eงu}ts pf the evaluatiosn:s of BMP groups are reported in Tables 6.3g through 6.3x. Interpretation
l!|; <||l<ซ^^ "I ,:
IIM'llil I' Hiii, ' ,
III!,I'I h'13!"'!! Illli, , ' ,,
Iii' i liilit^^ ,,,''
, " iilllli: ..... i": :" ........ 1 1,)- :ii , uni: ' ; ..... i: *>: fiXM , ""inn, 'ti .d1; >- ...... i A;: ; 'i' n ....... ...... , itUTicif1 ' ; alii 'i-'jiiTt /:ซ:'" jllliiR ....... ',; ...... iT'CTtiin^^^^^^^^ K "i /< I " " >l: I. ...... '. /'"it . : ,: ' , I' ; ...... , ...... Li,!! "'I
theie ..... tajjles ...... is as follows: ......... ................. i ...... ,I|IIIIIIIT ........ _rfii ....... ........ ,|p ........... ......... , ...... ...... , ...... ........... , ..... i ............................................ ....... . ...... ...... rir|iiiii|iiii ........... , , ................. .......... , i .........
'' B:ilj| 'i'i:.;1 'flfiftj''^'^^"!'! : i "'. **,'*:'. f^ST^'^-tlJ* t'i ',l*i,!. '!" SH(il:''';!Hi'lii,i( jLjBCff'!IT*1!!fl riB'-ii;.!1;: !''(! J, I "|J' ..... 's'i!': !;'. Vlr: ' . "I: , ,fi,,ft? f
' 1,6-74
Efficiencies of BMPs
il1 ,i'' ;, ',{ FTIIP1 ji
-------
Coal Remining BMP Guidance Manual
The first BMP group represents the reference BMP(s).
If the observed percent improved is greater than the percent improved by the reference
group. This suggests that the combined BMPs may have been more effective than the
reference group.
If the observed odds ratio is greater than one, the combined BMPs were possibly more
effective than the reference BMP group.
If the observed odds ratio is less than one, the combined BMPs were possibly less
effective than the reference BMP group.
If the percent improved minus the reference group percent improved is positive, the
combined BMPs may have been more effective than the reference group used alone. If
negative, the combined BMPs were possibly less effective.
Interpretation of these results cannot be made blindly. A combination of BMPs that is less
effective than the reference does not necessarily imply that the "added" BMP(s) are detrimental.
It should also be kept in mind that the comparisons are between discharges that had pre- and
post-mining water quality that was not statistically different versus pre- and post-mining water
quality that showed at least a statistically significant improvement (improved or eliminated) after
remining. Failures were not evaluated because they were so infrequent. Climatic differences also
were not taken into account.
Regrading and Revegetation
Regrading and revegetation, as mentioned above, are the basic BMPs required for reclamation of
previously surface mined land. They occur together, but without other BMPs, to affect at least 18
discharges. Tables 6.3g through 6.31 compare the success of regrading and revegetation, against
regrading and revegetation in addition to other select BMPs for acidity, iron, manganese and
aluminum loading. Tables 6.3k and 6.31 show the analysis of sulfate loadings and flow rate.
Acidity Loading (Table 6.3g): Of the discharges affected by this BMP reference group, the
number of discharges that stayed the same and that at least improved, in regards to acidity, were
Efficiencies of BMPs 5.75
-------
iliili,, I",",', ::",!: JivBlllt;. i'lll, :i . ', :, ... , d . .,
Coal Remining BMP Guidance Manual
. i1-*',JiJKliifi/
the same. One other BMP group (regrading revegetation, and special handling) had similar
^rejsult^^^ugh the sample size was the minimum of four. Only one BMP combination
iei |i ป,[,, j',1 d'"",::"" i," iiiii,, '''"mm: i" /"In '!' ;:',,'i* 'iw,1 ' iwiii ftiii ;iv, l'\j "'"v:\il'. ii11 tซ i;.'. , a:'';.'"'^ will!'" '"'T!'" i'i'lil* iii; - iw iiiii1'"'' ilitiiw II" L,*!,,!,,1',, "'"MM ' i-iiRiip'11;'1 [ .'iiii, . '...i^/fciriii'''']!!^^^^^^^^^^
(regrading, revegetation, and water handling) performed better than the reference. Again the
s|m^le size was the minimum, but all four samples improved or were eliminated. All other BMP
f !ซซ$
"
combinations performed less effectively than the reference group. The least effective BMP
'' ''vilk ;tf u ::l| m ti 1 .* 11. .w fv ปhWi'$: v" v,v.;: II , -'; '?!::, TO]- ;i TO iiW -i K ซ'ซv ".* Ji ซซ
., was regrading, revegetation, daylighting, special handling, and water handling, with
only one of eight discharges improving.
in:1 , " , , ' - B.'I i- - /TUP i,. i; . , '-'
illi'lC*1: JWi! SOi'lSi
I
I
I
"Loading (Tabe 63h): Two of seven BMP combinations were more effective than the
preference, group, and one was as effective, in regards to at least improving iron loading, than the
control. The most effective BMP group was water handling combined with the reference BMPs.
IIHIi'T ,'4!,ij!' , i"! II!!!1! 41. 'lii/l'iiiHIIIIIIIIIIEi... IMlllir'liiirii.TMiilii;]!1! li/m, : id, i ii,;"i i fi liil '"" ,,^M ' ' "n. \ซs .< v '. ' ." ' >,;, ^T: " i ii.i " L , ',. " ,11 ,"i,.i ",1:1 v : v";,n. '
,, I1
Iron in all four of the discharges effected, either was improved or eliminated The least effective
EfeM? SPJ'HiiiP^iSPM H^,!fe^,8trej*radmg> revegetation, daylighting, special handling, and water
handling, where only one of eight discharges improved.
I ii I;--T; ,
'mil in (Hi
^Manganese Loading (Table 6.3i): Again, the combination of regrading, revegetation and water
j: ,
Handling proved the most effective BMP combination, with all four discharges ^showing
improvement or elimination. This was the only combination that was more successful than the
reference BMP group. The combination of regrading, revegetation, daylighting, special
handling, and water handling, again proved least effective. In general, manganese had the most
failures (resulted in the most discharges with loadings that were significantly unchanged) of any
parameter. As discussed in Section 6.4.1, the ability to predict manganese is severely limited.
Mill ' I ,i"'!' Ji!'!!!!,"1!1
Aluminum Loading (Table 6.3j): Results for aluminum loading were reported less often than
CgงiiJJง forfte_oth^r, parameter loadings, and less BMP combinations are available for
""~ '" '' """" " ' ' ' ' ' '''' " ' '' " " ' ' ' ' ' """ ~ ~~ " " " "'" " '' ~ ' ' ' '' '
comparison to the reference. Although all BMP combinations performed less effectively than the
^ i>>ii!.'MSI
, Ti i,*is ' ii:! ;i, iiiiiiiiiiiii,; iiiiiii,' 'ii iซ;a ! iii'i i iiie ซa 'ป i ; si'' 11 r >.: vi ,; s ซ*< :;c ?; ' miiftw^.tsa ป* :ซWi if'ป,;, *' xtf t r ;';;,:.,
*fefe.rงnce group in regards to aluminum loading, the combination of regrading, revegetation,
daylighting, special handling and water handling was the least effective.
I HI i1 ant,: j ill!,: ii,::> ,iซ HJ,; i ''i>f -
[ i'V I 'l!i:l:.L Iff11 Klllll, :lll t
I I'ff'i,*: I), .hi.
, II" , Hi,I" , II, l,"1lll,;|l|l;nn
ii ' iifi'liM-i-Jl .;: ' i ,'i, "JliniHl M..WW'
lll'liii iiiii'" i, .||||;H;IIIIII ti
-------
Coal Remining BMP Guidance Manual
Sulfate Loading (Table 6.3k): As for other parameters, the combination of regrading,
revegetation and water handling proved the most effective BMP combination, with three of four
discharges (75.0 percent) showing improvement or elimination. This was the only combination
that was more successful than the reference BMP group with 58.8 percent. The combinations of
regrading, revegetation, and special handling and regrading, revegetation, and alkaline addition <
100 tons proved least effective with no discharges exhibiting improvement.
Flow Rate (Table 6.31): As for other parameters, the combination of regrading, revegetation and
water handling proved the most effective BMP combination, with three of four discharges (75.0
percent) showing improvement or elimination. This was the only combination that was more
successful than the reference BMP group with 66.7 percent. The BMP combination of regrading,
revegetation, daylighting, special handling and water handling was the least effective.
Overall
The BMP reference group of regrading and revegetation includes BMPs that are effective for
reducing pollution load by reducing flow. This is reflected by the fact that half the discharges
using only these BMPs showed improvement (Tables 6.3g through 6.31). Most.of the other BMPs
in the groupings are BMPs that are typically applied to sites that have acidic materials and/or a
lack of calcareous rocks. These BMPs are "geochemical" and affect water chemistry rather than
flow. The reference group out-performed 6 of the 8 other groupings that were compared. This
is probably because, in cases where regrading and revegetation were used alone, the overburden
was of good quality and there was no need for additional BMPs. The implementation of special
handling and alkaline addition imply that there was acidic material present and a lack of
calcareous rocks. Special handling of acidic materials, alone, may reduce acid production, but
cannot produce alkaline drainage. Alkaline addition, where it does occur in a comparison group,
is always less than 100 tons/acre. It has been shown by various studies, that addition rates less
than 100 tons/acre are not generally capable of producing alkaline drainage. It should be kept in
mind that alkaline drainage is not necessarily a goal of remining sites, the goal is that the water
not get worse. The BMP comparisons with alkaline addition at less than 100 tons
Efficiencies of BMPs
6-77
-------
Coal Remitting BMP Guidance Manual
per acre do suggest that alkaline addition rates greater than 100 tons per acre could result in more
improvements.
If; Ili't'RF:,;,i! ii; H" '",'< iiiii it: 'if': "i <. i - .iiiii. f m, Jjj : Is (,; , ^ I;:. i,. i '.F; j ..; i; fy;, \ '-,' >:;;, |:;; i -:,;.;, - -;| ,;$t;;;;.;; ii,, imK,: ^11:11 \&it i~.. f i \" j;:"f 1 i . i,' 4 ! wr iiiii JE v>',
For acidity, iron, and manganese, the most effective BMP combination that included the
I.STIIK ii If., 'iiiiii:' '(IP: ' 'i''''ti'ftft:.;" i-MK.'.'.tu "iiiiTi'ifc if,, i .u:;Tii'is , i,;.i i "vMy! ปr. ["aTnwktt''i1'st i: !*f'B;iปri:wปii.iij<'**.|**i' H'-iii* fttf ( '"uij* ':* < ' ? ' *ii'ซ"":! *!ป,>w<
i W>ff ฃ -I', i '\f ifeferenpe group was that of regrading, revegetation, and water handling. Water handling is a
j'1! I11;,:i!' L , I,!;, ,1 , t'. llllllilii;! I !'' '> .J' ill!!!' liiitii f' , 'i lijiiiK^ : /: j?ii;! f nil,; ''< i MA ' 'i'''' " wi ' JP -. i i i ' Wi l '- 11;" ,i Kป:' .' 'J: f" i.; ;: . "i,, l! ' \ ,' w ? luiiii *>!" si win si I'm ii'".! 11 ,ii Hi'1'!1!! rf *, '' * si iMi'M ,n,; w !' ' ':; Ji ', : fill11 miiinni J: JiLiU <''' <' nil I
physical BMP and may have further reduced flow which would further reduce load. The BMP
JS^' iij!j| ^'vffJSQibJnatioQ that consistently performed the worst was regrading, revegetation, daylighting,
JFV'M ll""|l,;l"lKiiiilii,, , "# >n;i llllllliillHiT'iiliiiiHTil'iiiJiiiiiii;!;;1 i!lnl,,"i :dJlliiii^^^^^^^^^ ^llhป^^l''l^ป|:l ' nil H ill Mi'lli, " li'Ni'M'"'!:!''!!' itil i::il,l 1"l ''ill111:1,!:!,!!,!'! !""i,,ili;' ,!: , ll aiFl;'1' i'lillMU "" lll'iiMil ''''irlWIHINiillV.^llili.v "'I1 i lllii'Mv.^!!!!!''!!!!^1 '''hllllEilltl''!!'!!. 'I'.liilr11,1*!1:!1 ii!1 '' 'II,,,,>,'ill,1,, ili',,ii ", l llllllllihll
; || l; j, ,
special nanHIirig" and water handling. This combination performed poorly for each parameter
i
and for each evaluation of reference BMPs. There is no intuitive explanation for this.
Daylighting generally results in acidic materials that need to be handled, and the inclusion of
IEi*jf,!*B' "Si' ,''ซ;,: i||i"';' i'"- ilffii1";""'SSi^ ''Sij'w "'< I-:: Jifti;;;:; J; ;i|' ii*:'i A . I ";'4;.";,'''":":;;"'" '>" " i* i,'' ",;;. 1; '.: 'iS^: ...;f.]|;;;i:i' \($ t i ' 'iif if'f" />'; ;ff'.^Ji?ft|B,
:i'J'';!!D^lig|ting' '' "
ipayiigiiting is the minimum BMP required when an abandoned underground mine exists within
l. IIIIHEM.'!.:'!1!!!'!!'!!!'! II'IIIIII irilll .1' ' liiiiiiiiliilil'''''!!*!!!'.!!., 'Illl, ''IIIIIIIIIBIII'TI!!1'!' L ' IfllllEIJIP1 'IliUllill . I' "1 ", TI'W !":! I'", I":.'!!!11! I, Illll'l!"'!'!',!: I ''' r "!' I1 i, ""I II",, "I'lltil1" '; ' jli ', jlill'li'V 111! illlllllllll'lii UK I,:! nil! Ill :p!' J'll> frill!'IBIIIIIIIIII^^ I lii'iilflljllllligi.' I1, T', Tlii .'' '! ป! lll'IIL 'i'llni'L' "IIPIPI, ': ,1','"' ,'l. Jill Ill'l; I lllpll'llllil Ill Illllillllll; ' , Illllill'lllli,
II (l|!|lllll:i||l|< 'fVlffl'VI W " Illllf'tW'!!! '''illlldlllN ll!': ' IIIIIIIIIB "I11 "'Ii HI''!"' H 'Ill"* "'I "I -il'llii'll >l' ''II I'M V'i 11'''''!'!:]'!'!'!'''!' '' "!(>:! 1:") I '! ' '"If.1 111! i lllllllBli.I'llli' IPI'llH ~R: nillll.il i I ;"' HI. ' 1 M" I' ,*''' '"I" 'UK!!1' ! , !lll> " 'I
|il?!R'!;'l* '; "" MiiSMjgairi proposed for surface mining. Daylighting by itself occurred 14 times and was
i"'1:, hi" iiij" liiin uih ir i rv iiiiiiiim'1 ;,',! ii'1: ,I|II:IPI "'fiiiirai ui IIIIIH"I,II iiiiiiii,ipiii" 1,11111, "i* ii'"1, "Vi ipiinii'nji' / inwp I'liiiip'iiiiiiiiH"!''!!' , ,nimiiiiii < 'IHIII'.TII ihiii!,, lii'iiiiiiiiiiiiiiiiiiiiiiiiviib' li'i'i,;1!!!; ;: \. \\\\\\ PI PHI , ,, :::i ,L > ', ::,i IMC,, : , \ ii u :,,",,i, ;ii ::""i' ,,i"iiiiiiiiiiiii:, IIMT ",'
associated with 7 other BMP combinations that occurred at least 4 times.
-it H,ipli!)ii4iiiซVyilir%iS viitfrifi;; 'i;^-;^.'.^-:!!'! L'O i&MJffiM-&i& i^i. '^"^M^'MM\
fsiciditv Loading (Table 6.3m): Daylighting implemented alone improved or eliminated acidity
",.] : iiiiK 'ii: I'liiii111 iniiiiIBป ,:ii " iui'i1! i, ,:,"ii' iiiiinr, iiiti 'iiBiiii!i:, ;::< i,;: > iiiini'. 'i'1;1! "",> i: v 't. '''Kii i!,:,:i'!ini,:;::ii!W^ ''iiiii^ 'iiiiiK ia^^^^^^^^^^^ iiiii'ii"". ::'ii!iii|!':]'i:.i<; HIIB : <:', i-i "j!! s-ri '.iiii'iiii 'iiu ii i iiiiiiiiiii "a
loading in four affected discharges, and resulted in no change in nine discharges. Six of the
seven BMP combinations were more effective than the reference combination. The least
effective performance was for the same least effective combination in respect to regrading and
revegetation (regrading, revegetation, daylighting, special handling, and water handling).
i
Iron Loading (Table 6.3n): Daylighting implemented alone resulted in the improvement of seven
discharges, and resulted in no change in the remaining five discharges. None of the 1 BMP
combinations were as effective as the control. The least effe.ctiye..cpmbinatipn_was..the same as
i i in i i Hi, ii iii iii iiiNn i j'iiiiii.m;;'i "m^ mim.' R'; i<"* *ซli'. is-K';ii: ^1. aB7ซa(^wiif'r'i'lili i- *''iiS'^M:mi?fmi... ^m'\m jiiim, m, \m \
the least effective combination in regards to acidity (regrading, revegetation, daylighting, special
handling, and water handling).
6-78
Efficiencies of BMPs
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Coal Remining BMP Guidance Manual
Manganese Loading (Table 6.3o): Six of the discharges affected by the reference group in terms
of manganese loading, improved or were eliminated and four remained unchanged. No BMP
combination was more effective than the reference combination. The least effective combination
was the same as the least effective combination in regards to acidity and iron (regrading,
revegetation, daylighting, special handling, and water handling).
Aluminum Loading (Table 6.3p): Because fewer data were available in regards to aluminum,
there are only four BMP combinations that were compared to the reference group. One of these
combinations (regrading, revegetation, and daylighting), was slightly more effective than the
control group. The other three combinations were less effective, with the least effective
combination being the same as the least effective combination in regards to acidity and iron and
manganese (regrading, revegetation, daylighting, special handling, and water handling).
Sulfate Loading (Table 6.3q): Four of the discharges (33.3 percent) affected by the reference
group in terms of sulfate loading, improved or were eliminated and eight remained unchanged.
Three BMP groups (regrading, revegetation, and daylighting; regrading, revegetation,
daylighting, and alkaline addition < 100 tons/acre; and regrading, revegetation, daylighting,
special handling and alkaline addition < 100 tons/acre) were more effective than the reference
combination. The least effective combination was the same as the least effective combination in
regards to the other parameters (regrading, revegetation, daylighting, special handling, and water
handling) with 12.5 percent.
Flow Rate (Table 6.3r): Two of the discharges (14.3 percent) affected by the reference group in
terms of flow, improved or were eliminated and 12 remained unchanged. All of the seven BMP
combinations were more effective than the reference group. The least effective BMP group other
than the reference group, was daylighting, regrading, and revegetation and regrading,
revegetation, daylighting, special handling, and water handling.
Efficiencies ofBMPs
6-79
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Coal Remining BMP Guidance Manual
ill''!!'!!.""''!!..!'.:'.!!''!!' 'I
': ill* >':i"i
iSMl',
Overall
The percentage of discharges that improved in regards to acidity from the implementation of
daylighting alone (Table 6.3m), is less than the percentage that improved from the
implementation of regrading and revegetation alone (Table 6.3g). Percentages of improved
""'"" ..... [[[ ....... !!F)L'l|l!|'SlTlP::?:T1f*lil'-1^'!:; ! ? -I: ; i'fif "Sill1 s'lll-1!1',1:1'111 ffiiWMMiHOT.'^ ''
..! I,,! irllin aill, iiiinilllili jllilli I! Ibl .i"r< illli"..!,,,;!,!
"Mi.f '%')&ฃ f
discharges'1111 were 30.8 and 50 respectively. This result is not surprising because, daylighting often
n^lfFWimim-iWttjj .............. irnrn^ ..... IMI:B ..... i;,t ..... &.$& ...... !t: ..... mmm ..... ^n'ww ..... w-ifflSfcvi:.. ........... *.ซ:ff
results in a large amount of acidic material that is spoiled. It is interesting that six of the seven
= ...... |r8u|mgs, ..... when compared'' to the reference group, 'were more effective ..... in regards 'to acidity
loading. This suggests that many of the BMPs, such as special handling and alkaline addition
_ ....... IM^^^^^ ..... Mfl ..... ii ...... ;i.ซjii :'''.. ..... LiK;K*imfiiEEtt;.%t ..... iiifii ..... ii! ...... ii ...... 1:1 ..... j ...... _ ...... t^
(even applied at lower rates), helped to offset some of the natural potential of these sites to
produce acidic water.
in 11 ii1 iii i in1 ii 11 i i iiiiiiiiiiii in in ID 11 mi , 11 ii i ii i i n i in IK
The least effective BMP group was again the combination of regrading, revegetation,
daylighting, special handling and water handling.
Regrading. Revegetation. and Davlighting
I 'i'i'li-iilfl: [:|'i;:P2S!Jfarge number of remining operations encountered both abandoned surface mines and
underground mines. Therefore, the minimum BMPs implemented at these sites, are a
combination of those in the first two reference groups, namely regrading, revegetation, and
llPi'lii!! HlllliiUiiliF , 'ri; yiii ! ! iili'l il, 'illilii'S''"!^^^!!!!*!!!!!1' IHIillllll!:'v' J, 11111"!: i'l'I'Ji, }ซ JilllEii]1 "P'" ,'' ;!'!|i"'i1',1| fiji! ,', v ''!!',|ป|i, >"" 'ri",; Xi- pJ'W "III":-':, ปV> ,1,1 A ,v ป, 'in, i .inir, '!* . X,lir , IP MiX, n , K i ,,.. "-. 'iimr, , ., <ซ, ซ ,
,,K:.;' ,, V i , f;., itf.?':, (;,:ซ. * i,":'' Jf -':!"!" < ';w :,i: ..... PI! - 1 ' i: .' M , max.fo i : '! :. . ...... >:< ' ' uMiiit;. ..::'. ft.* . ii:.ซ a1 ams, : , ..
itv Loading (Table 6.3s): A total of 36 discharges were affected by the reference BMP group.
lHFipl^H^!^'^^' ..... ilM.l ..... ^'i^'^I^Si^^^ilijiJ.flWaill ...... penii ..... rfWf-i-Siif-i
Sixteen discharges were improved or eliminated and twenty remained unchanged. Four other
BMP combinations affected enough discharges to be compared to the reference group. None
I liiiiiiiiir., ', 11
liiiilllllll I jlllHill nillll III!! "I'lllii
ฃv&re" as effective as the reference group (although three of the four were only slightly less
i:i:. , : "* , i iit:i.i .'.iif1:* . :.1 wuut i iiii .: iiiiiii ' ; '-i ..... iii.: 1.1 . ".iii..1":.)*. ..... cui i :. .M: >' : ' f , ',f :. in:i<ซ wr iiiwf '..-ii w i v ซi:;,!! , :!!ii>;ii ."iieii i.rii,.|f :~,a>'e* ..... ri ' . ivi >, ..... .it-iiiei* ..... ;
|||y.!|||ll.. I!1! ..... |."!|. ... . i!C 1 11:111! ..nilllllllK'li ,* mm* , :W, ....... I: MI ..;':. ........ |.|.:'l. ...VBiiini1 ::h: ..... 'Wi" I lil1 I. .:. ...il" I I'll:.: ..... I'l'llMi! ..... ;.|"l... li,'i ...Ji! lll'l'l .:.|V:| ..... .:.'' I, .illnlirl Inl, I... ..lAVeii.":*'.!..1;.: . ' .illllliifllBiil. ...I .nil' II! IK JldHillii: 111.11 11 jri'lllP''...::'!.!!!!'...!!!: ill ' !|."lli|iililli|.|ll inliij../ i| Jl'tlliilll,. ... iii.lilliii|i"llll
effective). The least effective, as in all cases cited thus far, was the combination of regrading,
revegetation, daylighting, special handling, and water handling.
i1!!!!!" 'iilET
I liui,, '.ii'lBII,
I "i',!'.1!'
I|i|'i.f. i;i:::ili[
6-ง0
liilli' 'ii'' ':(i
Jil. ' ii:I| i1 ป ; f, : ...... I/1., ''ii :' .tiiiiii ;
i: if ii| . ji1 j| :, I ...... _: , '.*
;, : "M i.
Efficiencies of BMPs
i; 'Mi.^'^-)^;:'!..!?] WJLCIf Wi, UBIt.i ..i;1! |
:|||H,'lซ "vi;. i'1: :v ill}.', \.llif ':'' ซ, ^,&';;:,''fi-ii nK! " ''' ,MJrf'ii"K:|': ",i": 'i:: ,'..t 1*.a .i, i..iS.''P;: .'; *!I-i i* ; !i""*"ijiii':1::'!^^^^^^^^^^^^^^^^^^^^^^^^i If''.'':-:il'
-------
Coal Remining BMP Guidance Manual
Iron Loading (Table 6.3t): Thirty-seven discharges were affected by the reference BMP group.
Thirteen were improved or eliminated and 22 remained unchanged. Two of the four BMP
groups (regrading, revegetation, daylighting and special handling; and regrading, revegetation,
daylighting, special handling, and alkaline addition less then 100 tons per acre) were more
effective than the reference group. A third group (regrading, revegetation, daylighting, and
alkaline addition less than 100 tons/acre) was almost as effective as the reference group. The
least effective, again, was the combination of regrading, revegetation, daylighting, special
handling, and water handling.
Manganese Loading (Table 6.3u): Thirty discharges were affected by the reference BMP group
in terms of manganese loading. Ten were improved or eliminated and 19 remained unchanged.
Three of the four BMP groups were more effective than the reference group. The least effective,
again, was the combination of regrading, revegetation, daylighting, special handling, and water
handling.
Aluminum Loading (Table 6.3v): Twenty-four discharges were affected by the_reference BMP
group in regards to aluminum loading. Eleven were improved or eliminated and 12 remained
unchanged. All three other BMP combinations that affected enough discharges to allow
comparison to the reference group, were less effective than the reference group in terms of at
least improving aluminum loading. The least effective, again, was the combination of regrading,
revegetation, daylighting, special handling, and water handling.
Sulfate Loading (Table 6.3w): Thirty-six discharges were affected by the reference BMP group in
regards to sulfate loading. Fourteen (42.4 percent) were improved or eliminated and 19 remained
unchanged. Four other BMP groups affected enough discharges to allow for a comparison. Only
one of these four BMP groups (regrading, revegetation, daylighting, special handling, and
alkaline addition < 100 tons/acre) exceeded the reference group for effectiveness by improving
45.5 percent of the discharges. The group of regrading, revegetation, daylighting, special
handling, and water handling was the least effective improving only 12.5 percent.
Efficiencies ofBMPs ~~~~ 6-81
-------
Ijll^ H]]? WJU'ifr-': '.I; !j lOTf^'fTCf:'?1 il'^:.;!),1,1? *!?.''
ilNIIIEI.piif ;:>1 IPi'lKiS,!, ''' " ..Inl {ill I' "1,'i:!, I! ',"!;'';:;"'i1'",;!" 'till'lii!:' , '" jlllliij', I'''/I"1'"" "< ,; "III! J I!;, "'i'l'i|i': I"!!', II !> / ' V ซ , i'" ""I"'< Jill ill"'"' J'"""i' I' " '! ml ''' 'illirf'i 'j';'illl''''1"!1':1! "',, ' ' l'""ir!!"ll< I!" I, I'fl'ii r ,M,'''''III" -',"'' 'I''"!' i,"*":'" , i' Ill i 'i!' ' 'i'lliilili''^'^'!'!!!**'; "ill!'"'
,, 'Coal Kemining BMP Guidance Manual .
Flow 'Rate ffable 6 3x): Thirty-seven discharges were affected by the reference BJyfp group jn
llllilliffllllliill'llllliiliilll11!11!1"1 ,,,'IKi: illilhl'1!1" "ii 1 I' 111,1,1 I1" "||,|D nliiJiBI,!;,,1, 'iJlllllilL^ihi'ililllllinilllllillli,1" Ji IIIIIIIIIIIIIIIB ill lift,'1" i i "" I, I'!'1' Jim i',:1;,!! I" .nil'1!1!" J ,' I1*' n/liinllli'll'l111: llf"*'' i"1!1 1 ' '(I, I1','", '"'ill'll' ',i, i'li'/inilllC ",!': 'if II!I.I!i"'i:!HJnfl!iHli:l!lf I"1:!1"!1! jifflSIM '"'liliJ.i ซ, iiliPlll'':!!!;''''!!]'..''!']'!^]!!!'!;;!!1 I'VIIL' ' 'hj'll'l I
'"". "'. !" Regards to flow rate. Sixteen (47.1 percent) were improved or eliminated and 18 remained
iii Si1 iii'i 'iiiii, <'; >, ilii f' Jiii'1- ii iliiii i J5ST!] S^aB't^siM^'. wii \ iii ii1 vS^iWii' 'liSiiiw i ,tvf' ' * -' i' i*: 'i:; ii:!* m:'1 "rfirafir iiiftxfisi' in: [.ป* nxii ,i i us " 'i;'1' .i, "iii:;: w'mjaSi 'iiiii : ':!iiii'!;!!!i I
!!!*^^^^^^ ''"';:-, JMchanged. Four BMP combinations affected enough discharges to allow for a comparison.
liK''']^!!!!!!'! :!'liii!'!!l' , 'i, ,,ii,., Illllllllliiiii'''''''!'!!!!'!!!!11 Jliijillii'ii'i]!1!1" wiaiiiiiiiiiiiiini111!, , imiiiiijiii i M n11 iiii""i," ''iminiuvi''!!!, iiu'Wi nil, iiii " "L iiiiFii 'iinv iiiirii1,1! :,> :,u " ,>i<,i,' I>IPI 'ซ,,11,11 ni''"!'!1',i, < r,i, m '< r,< iii,< >i"nmUK, :,iiii:iซ':.iซi, ,
None of these four BMP groups exceeded the effectiveness of the reference group. The BMP
;, revegetation, daylighting, special handling, and water handling was the least
reducing the flow rate at 25.0 percent improvement.
"iiil'w^ lirtiiiii ;i .Fiiiiii''!!'' i'ซซ tM 111 in i iiiiiii i in nil mi i i i i i n n i iiii n i i II i i i iiiiiiii iiiiiii
"'Illllllllllllll'',!.,'!!!:!!'HUB~,,!||I||I1III||I|I 111:1 "!'> ,'i,'4'
:::::;,;, ';,;';; ;,; ',; i|==;"; i;,,', ;;';';; ;:,;;:
The effectiveness of the four BMP groups in terms of acidity compared to the reference grouping
'Jiiiijt -, i'Miii''"ii:'aisaMiiHaiHKaKiiiixiirttiibt::r:HIJ ;iitwatw!;1;'! : >',, <::\
Dname. Abandoned coal refuse disposal areas are typically characterized by sparse
I' I ,' I1;. I It! jil! 1 . ''' ;"i!i':ji'li i*ff """' ' ' F!' it'>'' ' Iiiii!
, l;l> : _ _ i iJiilM ., Illill' illijilii. 1't'i '> I1!'::;; ji,:!' mime. I! "i'!;! *!. t' i 'i'liil:.: i'ii'"ii Ki lli";t f. i, Jii'iiilii; ', :i"i' iiiliUiiiii i'lJIIW liiliH^ "ii!W^^ i -/S >!,: " mSlA ' si 'i li'i: 'III
;e|elatipn and lack of "topsoil." Biosolids could aid in the establishment of a growth medium.
i
I
''III,l
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Coal Remining BMP Guidance Manual
Because refuse is, more often than not, acid producing, the addition of alkaline material would be
an appropriate additional BMP. The results of the implementation of coal refuse removal are
presented in Table 6.2a, and are discussed below.
Acidity Loading: Coal refuse removal affected only 9 discharges in regards to acidity loading. Six
discharges were improved or eliminated and three remained unchanged.
Iron Loading: Coal refuse removal affected 7 discharges in regards to iron loading. Two
discharges were significantly improved or eliminated, four remained the same, and one became
significantly worse.
Manganese Loading: Coal refuse removal affected 6 discharges in terms of manganese loading.
No discharges improved, five remained the same and one was significantly degraded.
Aluminum Loading: Coal refuse removal affected 6 discharges in terms of aluminum loading.
Two discharges improved, four remained the same and none were degraded.
Sulfate Loading: Coal refuse removal affected 9 discharges in terms of sulfate loading. Of these
discharges 2 improved and the remainder were unchanged. None exhibited increased loadings
(possible increase in acid production).
Flow Rate: Coal refuse removal affected 9 discharges in terms of flow rate. One discharge
exhibited an improvement (reduced flow rate), while the remaining discharges were unchanged.
None showed an increase in flow.
Overall
Two thirds of the 9 discharges showed improvements in acidity load. This is not surprising
because the removal of coal refuse can only be beneficial. Coal refuse is typically an acid-
producing material and is often associated with severe acid mine drainage. Removal of the coal
refuse is the removal of an acid-producing material. The two BMPs that typically accompany
Efficiencies of BMPs 6-83
-------
Coal Remining 'BMP Guidance Manual
;cqalrefjise remoyal^are^regrading and revegetation. Both of these BMPs tend to decrease water
JtJfUflJ; '' l*''..^^|ji^!^P|;|Al?t'9,^1P. refuse W^i^J an(^ thus, tend to decrease load.
:K; 'iiiiii, si" m:''m lir^di^J^K''";1 i i ' i i 'ซ I ii in1 i ii fi'ii
', rbve'rall 'Svajuation
Many of the multiple BMP groups when compared with the reference BMP group were not as
(;,, :
effective as the reference group. This should not be interpreted to mean that the addition of
BMP(s) to the reference groups were not effective or that discharges would have improved if the
i , |11 11 i III! iilillH ('IB 'II 'Hi I1 "1 iii i' (' 11 ii lli'ni1 illlli:!! VIE IWim W v-V,> I Wimm , , < .ill SI" im:: ''ill ffiK SII'';i :iill I
additional BMPs had not been implemented. The very nature of many of the BMPs that were
implemented indicates that they were added to counter either the potential for acid production or
ill!1! I;!"'!' "I Illll Illll Illlli II Illlllllllllllllll Illlllllllllllll I III Illll II I III II I I III I Illll Illll III 11II III III I 111 II III II I 111 I I III II I III II II I Illlli Illllllllllllll
to compensate for a lack of naturally-calcareous material. For example, special handling
generally implies that acid-forming materials are present; alkaline addition <100 tons per acre
suggests that naturally calcareous materials were lacking. Conversely, discharges affected by the
^iilfynlm'u;m, BMPs, may have had better quality overburden, and thus, not required additional
||||i|||||||| |>i|||||| 1 i!||||| !: ii f'i 41li!<: JiliiiiiJIttiif 1.Hi;. ii iiillllH'' Illlllllllllllll, i VS:SM til:1 iCi , US ; J* ^ *<ซ' -K nil ;: :WBi,p*'J _ ii i tiliil1: 'iiiltfilililiii r:::ป,:: iiilit i- CM ซ ' iillllK illi-lili: iii, ii I
BMPs. Also, some BMPs listed in Tables 6.3a through 6.3d, that were shown to positively
iiiii'lliilllliliiilii1:! Ul/jin^^ ''I illiiW: W Hill i,':Jjllซ,,,:I III' IliUIIIIXik^ i S H|, M * lll| |;' n ป, ';' ., | ปrl'l||||ll.Mil' ' ;I.|, IU|,,|; II ;lllll| hi, ,!,, i J.... |,l f , A VV!I|| , i IN, n h n, l.h I, ,^m il ; ; J, i, |LL l|:r< , h,, ;i>>>|i>
f'is!: ;!:li: /"I ; iinfiiience water quality' ^e"g."alkaiirie redis'trib'utibn ianH'mining g|g^_^aim'e"'sLtr.,1taj^ were not
used for comparison because of small number of discharges they affected.
i |n adc|itipn, although many of the BMP groups were not as effective as the control group, it is not
jjp^^^^^^^^^^^^ ,"> |!,! . . fm^'m^LiK'K^^W.'SA ^T&il^iiSmS:]s,4 W^ifmSSAxSSSS'i, Ii::i iieilii i 11 i 111 i n n ii iii
ili] ^i'liii 1.p:^^yw'JndJeatiQa.thง.t they were not successful. The fact is that very few sites in the entire data set
r !:=:!! ~-'^~' ' -:; '!!!!:=gdt w"o"rse'; This may not have'been the case iฃ'''t^ese'''a^^t|o'n^'g|^ps'''w^eje''no|''''use^
': :::: :; ':;'"' "" I ;
IIIBll!) J I.BJII Si ;; ซ, i, Fi; .IE , f il!;.;.; Will " |I1I;! S,1 '* f.1 _ ;*i lllf *f, .!: ti!1,!,. v IE.' i! 'M :;_ ' : :' fj2i I; <. ]-.'."' i 11 _" p Him fm ^itSe.S ซ'; i 'i'rซ. I' ,*/ "'fc ^ME.'.:!''. SHiilWf "I,: ,'.;( '!ซซ'!!, j ill!, X ""II
;;;:,,,;;;;::,;,:;:;,, ;:. 33&.lง3St งjfec&yง, B.M||;i,QQn^^aUon.1_y.a^.fegrading, revegetation, daylighting, special handling
and water handling. Only one of eight discharges affected by this BMP combination improved.
None of the BMPs in this group will add alkalinity to the mine site and it is known that special
handling, in the absence of calcareous rock, will not in-and-of^itself produce alkaline water.
Kr|iaps this should be iialcen as a sign mat alkaline-deficient sites can benefit from alkaline
a<3. i-!' : V JV:!;Rป*riJlf Mt 'j:':!,;!*-,,;-!' ;ซSffiPtM! .H*!'rMปปl( f 'BRtXaja'lNr.'3N/t:':!" .pซ!il:,T ,.i it.' ;:* J .tffcilWfM! lift' "iii1
terrns of contaminant loadings and in order to offset these existing and potential future problems,
in i n i 11 n i iiiiiiiiii: 1' iijiiii! '^i^iii JliiH iiiiiiniii.'!.!'; ii! i! :;i!'!' liirttjiff i, i iiii I!!' wii iliiuป. !'! !!!i!., li,, i j!i \: 1 vli I1!1: :iii: i:! i! i:!"' i': f i< iii' ill :i,i i, i ' 'iii!! i ikiiiii!!!: i liiiiii if!'!l >!i 'iiSn^ >li I: III i' ? ii:'!!' iui ''! !i:i i !i T jiS^^ i:
i'6-84 Efficiencies of BMPs
(1111 ill Iiii !"'"' X' i'm.":W+,K'\ "Si :';:[., K;:,-',i;.:'i: iii i; : ".;*.(: i,-!^ ;:.; i nl1 ,1, , i 'ill , > , I i1 ' ' I'ill 'Ill I, "
-------
Coal Remining BMP Guidance Manual
a variety of BMPs are applied. This sort of a "shotgun approach" to pollution abatement on
marginal sites may not be viable.
The low success rate of the BMP group of regrading, revegetation, daylighting, special handling,
and water handling also was seen in the significant interaction terms presented in Tables 6.3a,
6.3b, and 6.3c. For acidity, iron, and manganese, there was a significant negative interaction
between water handling and special handling. These interactions suggest that the positive effect
of water handling on the odds of at least improvement is diminished when special handling is
also present. For 89 percent of the discharges (in regards to acidity and manganese) and 80
percent of the discharges (in regards to iron) that were affected by water handling and special
handling, the discharges were also affected by regrading, revegetation and daylighting. Of these
five BMPs, water handling was the most efficient in dealing with acidity and iron loadings for
other discharges. Since special handling and water handling rarely occurred together in BMP
groups, the percentage of discharges affected by the combination of the two, that at least
improved, was very low. Therefore, the statistical models for acidity and iron isolated these two
BMPs as interacting significantly. However, since the interaction was significant, mainly due to
this five-BMP group, conclusions about the behavior of these two BMPs combined alone should
not be made without first examining why the five-BMP group yielded such low results.
Studies cited earlier by Smith (1988) and Hawkins (1995) showed that reduction in flow is the
most significant influence on load reduction. Regrading and revegetation are both significant in
terms of reducing flow. The other BMPs evaluated, with the exception of water handling, are
predominantly geochemical BMPs, which would have a less marked effect on flow reduction.
Limitations
As previously stated, this remining water quality data set for pre-existing discharges is the most
comprehensive available at this time. However, the results of these analyses should be considered
with the following limitations in mind:
Efficiencies of BMPs
6-85
-------
M ?;: <?, Coat Remining BMP Guidance Mamial
^'^ ป* ;|ปri' 'jjj^^ 231"discharges 'that were impacted 'by specific" BMPs "or
"""-BMP combinations are separated out, the number impacted, in some cases, becomes
ii"!!'!""lll' PI' i:1,"! lirl I ,;i illlll,, illp ta, , It I j,,, Kill''! ,1,, III,1!1',', 11,,,' {,! ill Hilli!!'!,,' ill IVIIIIIIIIIIH^ III'W I'f II'1,,, :l" I1,, |:!,,| 1111 'I' ,' i: "i, I, T I,1', ll,L ' tป ,, i n , , , ,, , y; , , , , , jar, fT:,,,ซ!, jni , , , ' v ,, , a ,,',, i : ,, I,, , , ,", ,| ' , n , ,' < ,, ," ,, ,' l ',,|,
g,f:r v::, =:ซ, E;,i: :=;; irrelatively small. In cases where smaller subsets of data represent each BMP or BMP
i [< Illiji,, 'if,''"' ;:>'; 't!',i|;,, f'lliM i' , IIIIBII , luil'i I" ";,,'!' ,,ii:" ,i;'- i W '1:1 i: ' ', mi, EBItii:, ;<'iirHli;,', n, I
vf |: ;; --I";1 iM|.")ii^'^|g^5u"pi, the number of results that are statistically significant at the 95 percent confidence
* i?:,' ',:'':, il i f:' 'i; ซ|lง Ygl ai| figvy.'," ', ,'.'"','''" * ^" I" ' ,, ",' "'"''"'"'!','""'"'"",'' .,""""'". ,,,,!'"'",''"""'.....'"" ".''""'",','"'' ,,'' '''''"", L:
ป The data collected for pre-, during, and post-mining does not take into consideration the
vaaaHKty of precipitation during the sampling periods. Water quality and flow data
recorded during unusually low or high precipitation periods can greatly impact
determined efficiency results.
.','".M'No consiicieration has been given to the probability that,' some discharges within a mine
I .-tto'fSii',' s,, trvt: 'ifiiiiiSsite have gained some or all of the flow that previously went to another. One discharge
a:,: ^ MJ .BI^M^,;.^^^^^ have-been'degraded, while others may appear to have significantly
Il'llll"!11 IS1 M: '"" "i Eli- Ii!!;" :-J "iijil'' fijK iiil JpSraHfe iilP' l"i"|ilt,i!' iS'f:';'f !|F"'; ; il..: X M;:' iiji'lif i;!, J 'lliOi ill 'siM :"S f*l MS!'\ ;''' % IfM! \ Ii i!;ป! p>' i' JW*C1; ;.:' #1: it I1'!, il' " ISIIf1' II i,
imprbved ||owever5 jge overall pollution load for the hydrologic unit may not have
111 "illill i, i,; UitilSI^ii'''! !;i. jj!11!;,:'i'lii i Liliiiiiiiiiii'11!;,! iiiiiniiiii ir<'<: i' J1', 'ii'i'1',, i.iflLu,: 'i1:":!1"!!! m,1, Ji'iium11*1, A '.:'.i,,,i i',;::,;.*!,,!11! i1:,1,* ' i,:, vfn;.!"1!!:,,:!!!,:'!!!!!"',, " 'iiiiwiaiii'ii,1 .s'l w niin i i'JiibiiiiiiiK, : ,';'iiii'i,i,in iiiiiri'iirr''"!:,: i"1!',1 'V:,iJ'!!"!ii!n ' i s
! If i' iilliii* ItJili' .';l'"!; IB^^^^^ v'' , W'*!;!!,: tyKE&'' III! ..{i;'','' :^#\ "* 'tl1'. if -it '';:": i=,',': I; "I ': i"' ' f!ซ'f E' ' ;?!' (il ''* '"'I' ill' *'! Si'til? -P $$!, 1) Js'!1?:;,; 'v'1 .i';:'' :"'$'"';" '': rปt"' ^ i- I'ill'
I iia^^^ ;.,,!.,. 1^^^^^ ,1 1!M^^^^ ii,a ii.1 ii iiiiiiil B
I
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Coal Remining BMP Guidance Manual
Those BMPs that exhibited a significant failure rate for any pollutant had no more than 2
discharges with significantly higher loadings. The most efficient BMPs varied according to the
target contaminant. The number of discharges that were observed to be made worse during
remining was so low that they could not be used for meaningful statistical analyses. This is
illustrative how successful remining and the use of appropriate BMPs can be when properly
implemented.
Remining falls into four categories: (1) reaffecting previously surface mined areas, (2)
daylighting of underground mines, (3) refuse removal, and (4) reaffecting previously surface
mined areas and daylighting underground mines. Each of these remining activities has minimum
BMP(s) associated with them. For example, remining of previously surface mined areas requires
regrading and revegetation and where deep mines are present the minimal BMP is
daylighting. Minimal BMP groups were determined for each of the above four remining
categories. Frequently, in addition to the minimum BMPs, other BMPs were also employed
during each of the four remining operations. This allowed a comparison between the minimum
BMPs for a category against situations were other BMPs were also used (minimum plus other
BMPs). In many instances,' the discharges affected by the minimum BMPs plus additional BMPs
were less effective (had less "improved" discharges) than the minimal BMPs used alone. This is
attributed to the fact that, in situations where more than the minimum number of BMPs were
implemented, it was probably due to the presence of acid-forming materials and/or a lack of
naturally occurring calcareous rock. In these cases, additional BMPs were added to counter
negative characteristics of the mine site overburden. In contrast, remining operations that
implemented the minumum BMPs, probably had overburden that was of better quality.
The BMPs predicted to be most efficient for acidity load were those that added alkalinity to the
operation, such as mining into alkaline strata and alkaline redistribution. However, when the
amount of alkaline material added was small (< 100 tons per acre), the predicted success rate (at
least improvement) was one of the lowest (25.4 percent). This amount of added alkalinity was
insufficient to successfully prevent or treat AMD production. The finding that BMPs that
incorporate calcareous materials into mine spoil have a positive influence on acidity load (i.e., a
Efficiencies of BMPs 6-87
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CoalReminine j^P_Guidance_Manuql
reduction'm'loadymay' seem obvious, but is significant, previous studies of rerriih'ing have
I || || I III || iiif1'."'!!!" aitjii'',;,!!'!! r|f|.l||H^ If.lill!,,1:'!!:,,':,!::!!:,!!:.!]:;!! llillJV,1 'W U'1' >l: "! Mil" Ki, ,:,' ''I'1'11! '"K, "t1 ,!;.ป ' X "rlJiMii'1 i:"!,,.:]!' : ri,11:1' Hull: III!1',:,ซ,ซ III lIHl':!;;'! "'I * LITIiiiin1" IK' li1' I .: nhi?,!!!*11 ' iil'llll::"!!'1!' IB I" HIV'SMI Is I'lli'liiilllllllllliiiili'llir'III'llllllllllllllilT iiiHiilli1 .^'il'lliill
i'i,ii 'iiniiHi i inn n.i'ii iiiiiiiiiiiiiiiniiiiiijii ''nLiiiiiiiiiiii'iii ,,i,ซ'i i1' Jif.L' iiiiiPiin, "'INI Biift i'1' ',;< iiii!i!iii|ii|i 'i, , Hi1 ' /i. iUi ' 'ii'"ป '' ' "i Jk,'; pmifN ' 'i ..v i ini t1!1 ' ':,.,.;' IIIIIJIIT "'iiiiijiiiiiiiiiiTniiiiiir'i,,!, 14,1, tr iiiiiiin1 p: i, iniMii":''!, ,'Ui niiii ,, ,ri iiiiiiiiij mniiii;1.' ,;i ; Anur; ir'niiiWiiii'iJiiiniiiii,
erripHisizeS the role of physical BMPs in reducing load through a reduction oFflow. Chemical
'SSiiซ*I''k\*^ .'t!"!|riBMcJ5ป sucE.as allcaline addition or .alkaline redistributiQn, are unlikely to have much, if any,
I;idwป ..... ' i, '""i Wili : "" I!" "t '< !' 1 ,'! > , -"ill! ..... IPE ni ..... ; , Ii '!; i I'Vi't Hiii ...... f If innt^iHtiVHR; :.3i I liH^^^^^ ':' !! 'I!1'", : , '"mti!' ' Ii: >" m HP I!!1,;)
iiiiiiii"!::' 'iLiiiiigiii.iiliwiinniii^^^^^ ...... ^'Jliiiuii'hiiil'gina ..... M||||,ป'|:! i, '' ......... : iniii nil i n il i ,,i ' ,": 'in; iivii...!*!^'^!!!!!!,,,,!!,,,:,,!:.;;!!!!''!''!^^^^^^^^ ..... i'',',iivi'ii,i,,'',iii|iiiii ..... 'fi,, ;,! ,': "i ' i,,1, "i'i', if ,,iyiiiiiiiiiiiiii:,ii;i:ii::,i, 'ii',i:,i,,iii!:vi, H^ii1, iiiiiii*
ill ..... whether the change in loadings was physical or geochemical is expected to be more definite.
^jkliSiCTi',* W*i, i? % 'r ซ >* y^/^'ttl^;-1^ .V ^r ,:': '^ii.^Si '>l:'^,i!'i*ifflff^i';,i ''A i'iM"^
u^
.! .mt'lt 'ii \
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IJIIIiy1'11!! U ' i'." i"" '"1111'"
..... \ '^ ;i ..... , ^ is iiiin ' } i1 !' i. iiihiiiiiinii: :;;i"i " " "i l!i' ,t ' "iw : ri .i ;i ' ! ..... i* '' ' r 'i!i"'i , - ฃ -J ". .l
..... ; ...... Ijt11111!!!1!!1 "IN ,,"* j !i.j,.iii'i:,.4'r! 'I. i',!1: lf ..... fii1 !' I1* ....... I'"
; ^ ..... ^ m^ \ ..h w- 1 ' nu '14 \ w v:
!' i,1, i I'll ,.|i' ''iilllFIl1* IS1; ' , mi!*
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Coal Remining BMP Guidance Manual
References
Agresti, Alan, 1990. Categorical Data Analysis. John Wiley & Sons, Inc., New York, NY, 558 p.
Brady, K.B.C., M.W. Smith, R.L. Beam, and C.A. Cravotta, 1990. Effectiveness of the Addition
of Alkaline Materials at Surface Coal Mines in Preventing or Abating Acid Mine Drainage: Part
2. Mine Site Case Studies, In the Proceedings of the 1990 Mining and Reclaimation Conference
and Exhibition, Charleston, WV, pp. 227-241.
Hawkins, J.W., 1995. Characterization and Effectiveness of Remining Abandoned Coal Mines
in Pennsylvania. U.S. Bureau of Mines, Report of Investigations-9562, 37 p.
Pennsylvania Department of Environmental Resources, Pennsylvania State University, and
Kuhlmann Ruggiero Engineers, 1988. Coal Remining - Best Professional Judgement Analysis
(REMINE).
Rose, Arthur, personal communication with Jay Hawkins, 1999. Details available from the U.S.
Environmental Protection Agency Sample Control Center, operated by DynCorp I&ET, 6101
Stevenson Avenue, Alexandria, VA, 22304.
Rose, A.W. and C.A.Cravotta, 1998. Geochemistry of Coal Mine Drainage, Chapter 1 of Coal
Mine Drainage Prediction and Pollution Prevention in Pennsylvania, Pennsylvania Department of
Environmental Protection, Harrisburg, PA, 22 p.
Smith, M.W., 1988. Establishing Baseline Pollution Load from Pre-existing Pollutional
Discharges for Remining in Pennsylvania. U.S. Bureau of Mines 1C 9184, p. 311-318.
Tukey, J.W., 1976. Exploratory Data Analysis. Addison-Wesley Publ., Reading, MA, 638 p.
Efficiencies ofBMPs
6-89
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Coal Remitting BAdP Guidance Manual
I iii" 'ill1 ( (
I'll
II " i|i Chi II ' i i I1 1(1 II
fill1' "l "I p 111 1111 11<
ullll1 I i n II i ill Ml1 " 1 i II
,
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I
,1
i I 1111
nil i 11 mi 11
in n i ii n in in in n i 11 n n 11 iiininn in in n
11 i 11 1111 i lill
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(5-90
Efficiencies ofBMPs
m in
I linn m i ii lull 11 iiiiM i tiiiiii i i ii iiiiii in iiiiiiini mill iiiiiiiii1! i mm ill iiii iiiliiiiiiiiiiiiiii iiiiiiiiiiii iiiiiiiii iii nmiim\ iiiii 11i. ii I
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Coal Remining BMP Guidance Manual
Section 7.0 Best Management Practices - Costs
This section provides a summary of the Best Management Practice (BMP) cost information
obtained during the preparation of this document. Although not specifically requested, a
significant amount of BMP cost information was obtained. This information should provide
mine engineers and permitters with at least preliminary or "ballpark" costs for the BMPs. This
cost information should not preclude detailed engineering analysis and design efforts to include
such things as location, climate, and site limitations.
When sufficient data were available, a least-squares-best-fit linear regression was done on the
data to come up with a cost equation. When limited data were available unit costs were
developed and presented.
The primary source of information used in the preparation of this section was 61 data packages
gathered from six states and representing remining or reclamation activities during which these
BMPs were implemented (Appendix A: EPA Remining Database). A limited amount of cost
information was found in the literature. Abatement plans from several state's mining permit
applications require the applicant to define which BMPs will be used to abate or ameliorate
pollutional discharges, and estimate what the BMP implementation cost would be. This cost
information has been summarized in this Section in table form. Very little has been done with
the cost information other than indexing to today's dollars with the aid of the Engineering News
Record (ENR) Construction Cost Index (ENR, 1999).
Unless otherwise noted, the costs were considered current with the date of permit application and
have been indexed to January 1999 dollars with the use of ENR's Construction Cost Index.
January 1999 has an ENR index value of 6000. For example, the index for September 1995 is
5491. Dividing the January 1999 index by the September 1995 index yields a factor of 1.09.
Costs in September 1995 were multiplied by this factor to derive costs in January 1999 dollars.
BMP Costs
7-1
-------
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""''''" .......... ''' ............... ' ...... ' ' .................. " ' ........... ' "ll" .......... ................. '"''"' ............................ '"''''I .................. ...... .............. '' .......... '' ......................................... ' ' '"''
Coat Reminins BMP Guidance Manual
iiiiiiiiii 111111111 ii ii 111 inn nun nun i nil i 1111111 n i iiiiiiiiiiiiiiiiiiiiiiiiini iiiiiiiiiiiiiiiiiiiiini mini in i i n nun in inn in nn iiiiinn in in i n nn nun 11 mmr iiciiiinnipii'i".1,.,'!!!!,!'!!!/!'!!. .L^iPiiii, ''niiii'iiiniiiiiriiiiinnnnniiniH .Li'iiiiiiiiiiSi'i'iiJiiiiiiiii'iiiiiiiiiiJlMimiiLiiiii'iiiii n\:aM -.M iviiiiiiiiiiii\iiiiiii\:4iiii.wJu>iiinniL ni iii^iiiiiiiiaiiiiiiiiiiii'iiiiBniii
The cost information has been summarized alphabetically by BMP. Within each BMP the cost
i information is summarized by mine followed by assumptions underlying the costs, and finally,
IlillJililLhilillllllli |ii| Ilillll 111'il "I I, II .il IllllIB liilllli 111 I i llill Ilillll 111 P IIP llliliM I jll 11 nil IHill I III I I III II 111 til lllllllll li.l illllli .1111 III ill III Jill pill III III III J P ,'
cost equations generated from the available cost information (if possible). Cost information for
the following BMPs are summarized in the following tables:
Ilin fliilllllE'li!11!!!
MP
Table
1. Alkaline Addition
II, ,,,! IMlii, ii ....... >!' iilllll ...... ''il Ililflll' S'Pfll:, ' ,' il'l'iil ;B, ..... mil"!,!'! ojlj : ;;;| jniir "I .."'.;si iff!,.; ! .;,,,, ''in" ...... : ilil'f',"!), <'
7a
I', '-ill IKH-.nn ' lilinlK'ii:; III, 'Mil'"''.1!' ",:,' 1' , .; ....... lilT'iiXiiC" :,''"T '! "'HI : ..... I'liVsiiillSii .', ..... llllllH illiiai I
...... li: ; ' m f r *' 5i w 2- .............................. Anoxic limestone Drains .................... . ....... . .......... . ........... . ................. ". ........... I ........... . ........ '.' .............. ......... . ............... 7b ..............................
'^' :|H'l. ..... *'"H:rป" ....... ! ...... Ili ...... ill ....... " ..... f^n-wi ...... w$wl ..... 'SM^^^^
$tf;''lij:it$?f & ....................... ,.4งh,]SJlPjaoement, . . . ,,;; .v, | ,. . . ..... .,_ , | . ...... , ..... , . ......... ,,,,_ .;. ........ ,, ,.,,. ...... . _, .. ; ,,,,. ........ ,,, ;:.; , ,, ........ 7c ...... , _ ^ _ ..... f .................. _ ..... _ ............... ..........................
ป!*" : ' ii'i1 'I1 'if. rf ?"ฃs^S. lii $i^ j1 il";:i:': i ' ll!1!' f',J v 'Cllf ' "1*1 '* ": ?:;il i i1" i . ! -ฅi ' ; :tงl %!f:H$!iS l1'.!^'.-1 ^s ":: ii, i;!;ii :;!l ': '.i SM;1 ' ..:' if ' l*':lil lii j ill
'"'' ' E ..... "' "':i ' 1:; ..... ""41 ............. """ ...... Bacfericides ............. """ ..... "" ' . " ' '. ............. . ' ".'" ". ....... ..... ' "" ' '."' .......... '.'' ......... . ' '"'.'' .......... ."'
7d
' ;;,:~-,' ":.: i::::'"" :::-,":;;::: 5- Check Dams
7e
|iflilh''i*ik<.tpK:iM ii i Till";I 6
fiii, "?B ':'|!!:l'i1 (:ง;i:*ff':
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Iiiiiiii11 ;. i'!1 ' iiiiiii1:, "|:,',r Hraiiii, "~j
iiiiini! i ijiiiri 11, ,;,:!,. ihriiiii' i'i; i1, nniiiiji1 . i '' iirim; ;,;i ,1;
CoiTstructed" Wetlands
7f
MJฃ i ....... !i!l!i:!B ..... ilP'ii SI v , t ;. I-'ฎ*!,' ' : :i' ;: ill : Hi :, i' II i;*!, .VMi&iaWi ..... IS II3 ..... Ui?ii;::i*j^: SMS: ii:
jiiiii'i'iii'A ........ ซr:ii; ..... ""iiriiiiii'i a ........ r ...... i ,",1 ..... a.ts ,:.<' r, ...... ...... ''. ;: "iwi-'1",! ....... -t,:a\'-. ;::4Hkiฃi ^riiatii ...... as 'in ..... s ซui:*ซi' ..... >
Daylighting ............. 7g
" iS, 'mm, m.
;S' v. ..... .-i ............... n ............ \t s ..........
8. Diversion Ditches
if tiiis Mi'.' s' ซi: "!' itf ! *:, 11!11 9. Diversion Wells, Alkalinity Producing
Hi, 11111111111111111" ' i mi. ', T : llll|l|llllll!ll I* i "!'!'! ป!, :'l ilUIIIPillH .n lllllilJllllllllllil iillllliiillllll ,'il! "1 l|lIIIIE"BI|1i 11 Tl ,!.: , 'ililllll. ""!::,: . ',n* 'L:!^''' Special Handling of Acid Forming Mlaterials '.
IIIHIIIIE' EffillllEfi'E < /illlllliilili . ':' <1'1|! JlllllllliEliliE i "U il V< ,1 -' itซ,14 4 I 'P'llEIINIIli:, i
7j
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7m
7n
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ill I"!
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11 ii'i nil i;; nit 11 liiiFHiiiiiiniiiiiii , ;i'! i"''ซ iiiiiiii .i"' -,, i '; "ii: vijinnin. lUjiniii 1*1,;
I ;i:i'W^^^
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n i iiiiiii ii
I ...... in ..... niii ........ i
,1' 1, '1,11 iiliilliillliilf' ,1 Ill In, ill Ill 11 11 llllillilllii 'iiliill I, ill I nil N II In ,1' nil Ilillll ' 1,1 illliil 111 111 111 ilillll 1 111 lill|jll Hi llll I lllllllll 1111 lin^^^^ illllii II Ill i nliill liilllllll lllllllll lllilil 11 III Ili
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Coal Reminins BMP Guidance Manual
Table 7a: Alkaline Addition
Mine
Acres
Alkaline
Material
(tons/acre)
Location
Alkaline
Addition
Cost
($/ton)
Cost (Date)
Unit Cost
ENR 6000
($/ton)
Lime Addition
PA (10)
PA(1)
PA(ll)
PA (8)
PA (19)
28.6
26.1
61.3
22.68
9.8
3
30
50
403-493
1050
Spoil
Pit Floor
Pit Floor
Blast Holes,
& Pit Floor
NA
$ 17.50
$ 16.852
$6.00
$ 5.003
$ 10.00
$1,501 (2/90)
$13,194(3/90)
$18,390 (9/89)
$68,040 (2/93)
$102,900(12/97)
$ 22.40
$21.55
$7.73
NA
$ 10.24
Ash Addition
PA (2)
501
$2,608,000(8/88)
$2.55
NA = Not Available.
1 Ash and refuse will be placed in alternating two foot lifts, reconstructed pile estimated to
contain 1,650,000 tons of refuse and 1,350,000 tons of ash.
2 Cost includes $2.25/ton handling, $6.00/ton trucking, and $8.60/ton lime.
3-.Cost includes $ 1.00/ton handling, $ 1.00/ton trucking, and $3.00/ton lime.
Assumptions:
Costs include lime, trucking, and spreading.
Cost Equation: Not developed.
BMP Costs
7-3
-------
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Coal R&mining BMP Guidance Manual
, at Si'":';,!."": :iilW^^^, ''ปi<> 11 ivl-ISL./!!.! .Si,I';',,: WKfTIt: .>; ../it;I Jiidiiirt'JilBlllll1 lllillLi!!1"i i
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TabTe'fb: Anoiidc'Oinaiestoiie JDirains''(AXDs)'
,ini!iiiiinniti "; "iw
Mine
TN(3)
TN(5)
TN(2)
Design
Flow
(gpm)
8
160
200
Loss of
Limestone
(mg/L)
250
250
370
Design
Life
(Years)
40
30
10
Design Loading
(tons
CaCO/gal-min)
33
201
20
Cost (Date)
NA
$ 90,014
(5/94)
$ 230,0002
(1995)
Unit Cost
ENR6000
($/Ton of
Limestone)
NA
$31.42
NA
J Design loading required 4,000 tons of limestone; 5,000 actually used to provide safety factor.
.iiiijBIIB' iniiiiijiiiiii jNili if,, in Jiiu:.!; : i ;"IP .ซlllllliir * __ ~ " "T " _ :_ir - LL ~~ . ,ป -
'xsvsxis!:* 'irs:isl,Costs are for a 5,000 ton ALD and a 2.35 acre oxidation pond.
KiiiiPl f llilililiqil'f'igilty'ilililillllll
1,1 13. !i i.'ซ";' SSltJMf,^ 1: :>: [i.:;:m\ <>A''.->'.'^ Ililil ';>ป'ป IIIH :!>^lllllM Ifi'i't liP1 Ilf
l111:!;!!!!!!!!!1^ Ulli ' M i Jliliilh,, l,n < v ,,111'III'1;! lillt HI "'!! j ซ ' Pull1 niC'Illl vH'li IT .'IK1'I '"i1'1 !!' '' .' ,, ' , I1 RiriilllQ'i . IlLI nillil A11 nllh II' I '.US 'IIIIIIIIK 11 iif'l.,, I " ill I I ''IJ'I'I1' '"'bt ilP1'!,!' iJII'li'M " iHIIH' I!
F;t; iliiiii1! "Fi:,.,if1 ii's: , TJNf(2 j - 5,000 tons of limestone used; loss of limestone 370 mg/L; design life 10
I|M ; ii: ia , , , ...., years.
IllllllllllllUnlii" Hill, i,, i
i^^^^^^^^^^^^^^^^^^^^^^^^^^
IB, i .I uk I
- 264 tons of limestone used; loss of limestone 250 mg/L; design life 40
; ,i; iinr years> safety factor 1.5.
'?!? :"- i^ of]]^sion&^0'myL-''Sesiga':&fG''^(i
years; safety factor 1.2.
ii".:!,*"! i;i|.ill fi!'
' llCost Equation: Not developed, only one point available.
* ...................................... ' ...... . .......... , ............ ........ , .......... - ....... ' ................ u. ........ . ........................... r ........... . ..... ............ ...... .......... ....... r .......... . ............ ..................... ...................... ป ...... ................. , .
. ': Illllii';, i'''lf,ปซnft MB- Vllllllli! i ...... I! : ' i" ...... -irll'vi""'1 -tB ..... 'V s ...... 'IB ;: , E " i1 ....... ' "
,
' >"' I! ..... '" "IS ' f ซ ..... ,'iilป.l!IWl,'ff i" ....... S ..... 111' i!" ''ill! ..... f ..... SUM ;,ni>!:"'': .'!!*
ill 111
I'll
I W
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i..' ป''', i1 '
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iv: '
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iii I
I
BMP Costs
........ ii'i; ii ii i jffl ...... !: ป ' ai- ;& n ... ,*-.. j ^SM. ~ ;",": l!: : i ^ ; w -f IJ mi:1;1 .-m m-^ w^ ..... nil i JR j m&
' : ' ;; ...... ll: ........ ' ..... : ": ..... ! ': ..... :I" "" .............................. ' ' : = .......... : ' ;: ::"" " ' " ....... "' ' ' ' : :l" ' ' " : ...... " ' " :::l ..... : " : ' '"::" ...... " ...... ' " "'' ' " ' ' ' ..... ........ ' ..... ; ' '" ..... ' ~" ..... ": ' ' ........... " ........ :" ' ...... "
..... !CM ...... i;;.;:!^^ ..... .{'.it: W {.iiiil^^ I
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Coal Reminins BMP Guidance Manual
Table 7c: Ash Fill Placement
Mine
PA (18)
Cubic Yards
15,000,000
Cost
($/cu.Yd.)
$0.25
Cost (Date)
$ 3,750,000 (12/96)
Unit Cost
ENR 6000
($/cu.yd.)
$0.26
Assumptions:
Cost are for handling ash only (hauling, spreading, and compacting)
Cost Equation: Not developed, only one point available.
BMP Costs
7-5
-------
Ill III I 111 I 111 I I III IIII 111
Coal Remininf! BMP Guidance Manual
Table 7d: Bactericides
I llll
hhllllli i< :, ,<:<'", 'I. 'i'i! , ' 'i,'iซ'llll'i'i|iii '"i i, I,,'!'!'; "Hull" "i1!
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",'''I'"ill! ,'"',,, " li J!' 'mill! i', I'/'I'lllilliLIII IL"illllllllilllllllllllii< irill'lllllllllllliNu'lilii"! hilli
" * IS' ii"! 111"!": ''llซ. i i' ' i1; !>'] 'iillii ,J illilll ,!-! "',! 1 , Si:*:8 !. i*l i.:!' j!: " . il , --i, '", :" 'M Iliiloi I -1 "' '., ' ;, 'i'llil: : ' I l> r t"" V IBIS!1, IK '*"' J Kill'" I'i'S ,;.: %ซ(' '> "': :,i., X > ;' t ri ซ WlilSBIli lifHTJtซ
'>|l"l":'i< ,!"' im;r .f.!,'ซ:: l-'ilnlifniri'liii linillllllli: HI " I', " n'lii1';.;, II , 1! jll! "hi n ll.jilU'f , ' "
il'illlllllllll'll IlllilJJII In,,,!1,!''
ii':u!1iiiiW 'Dlllliiilillili: ,''; i.!,' j;ii I
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ii; LtM: 'SS"
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i. ISin I
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|iซi:!',"' lซ, " ]lM#-'Mil" ih ', lljill!11!1'1'1' 'ij!'!1!!' i, f1" "|!i|ij "I'j'i 1!!!!!'!"' ป '!'<'!!
,,'fi;1, Hi n iiiiii; . ' mi t 'j, [^tfriw- rijiM^^^^^ j,':,,!1!
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IWIiillli ,,i' Nl. ,,,'"'|i, II' "'iiJil1;;,,!!!.'1"!!!!!!1!":'!!!1 '"l",,n" iFI1'1!" I,'**,"1!1''!!' III ill n1 , '" 'I'r.'Pii!'1'!' ' ' illl 111 IHHn1,!;!', " >,
''iiS'!,' ,' ii'ii'1 ป',?'!ป '''''''"iiliiiiiK^ii'''''^'"'^ ,1';i!lliiii,;;vlw ' ''I '""iiiiiii.""1,!1'1'"
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,
inii.'ii1 '^: m [^Wr^,mwwwr-.>w*w-.
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ill
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In 'III M
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,
!|
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,
I ;>!, i Liii-iiH AIH^^^^^^^^^^^^
!,!l:,l,ra^^^^^^^^^
l],IH^^^^^^^^^^ !iiH
-------
Coal Remining BMP Guidance Manual
Table 7e: Check Dams
Source
Ref. (USEPA, 1992)
Cosig&ate)
. ' ;p>st; _.
: ENR6(M) ':
See Below
Assumptions:
Check dams are appropriate for use in the following locations:
1. Across swales or drainage ditches to reduce the velocity of flow.
2. Where velocity should be reduced because a vegetated channel lining
has not yet been established.
Check dams may never be used in a live stream unless approved by the
appropriate government agency.
The drainage area above the check dam should be between 2 and 10 acres.
The dams should be spaced so that the toe of the upstream dam is never any
higher than the top of the downstream dam.
The center of the dam must be 6 inches to 9 inches lower than either edge, and the
maximum height of the dam should be 24 inches.
The check dam should be as much as 18 inches wider than the banks of the
channel to prevent undercutting as overland flow water re-enters the channel.
Excavating a sump immediately upstream from the check dam improves its
effectiveness.
Provide outlet stabilization below the lowest check dam where the risk of erosion
is greatest.
Consider the use of channel linings or protection such as plastic sheeting or rip
rap where there may be significant erosion or prolonged submergence.
Cost Equation:
The costs for the construction of check dams varies with the material used. Rock costs about
$100 per dam ($ 119 => ENR = 6000). Log check dams are usually slightly less expensive than
rock check dams. All costs vary depending on the width of the channel to be checked.
BMP Costs
7-7
-------
Coal Remitting BJbfP Guidance Manual
Table 7f: Constructed Wetlands
Mine
TN(5)'
VA(8)
TN(2)
Fe Loading
(gr/day/m2)
20
17.2
Mn
Loading
(gr/day/m2)
0.5
Ox.
Pond
(acres)
0.762
14.2
2.353
Marsh
(acres)
2.69
2.0
Total
Acres
(acres)
3.45
14.2
4.35
Cost
(Date)
$21,559
( 5/94)
$ 284,000
( 9/96)
$ 21,000*
Cost
ENR
6000
($1,000)
$ 23.93
$ 299.84
$ 23.03
NA = Not Available
1 This wetlands design includes areas for an oxidation pond and marshes in the calculation for
required area of wetland. Oxidation pond designed for 24 hours retention at 160 gpm and 5
foot depth of 6,160 sq. ft. (Actually used 33,450 sq. ft. At 6 ft. depth). The remainder of the
wetland >yill be marsh (150,790 sq.ft. - 33,450 sq.ft = 117,340 sq.ft.).
2 Twenty-four hour retention minimum.
3 Minimum 1 to 2 days retention; 11.0 actual.
4 Costs are for the 2.0 acre marsh area only.
Assumptions:
Refer to design criteria in table above.
Cost Equation:
i1 , ,: , ' ' ; ii
Least Squares Best Fit Linear Regression expressed as y = axb, (ENR = 6000):
Wetlands Equation:
ENR = 6000
$1,000
f
o
ง. $100
y = 6.41x1-405
^=0.93
co
O
O
$10
y = 6.41X1-405
where: x = acres
y = Cost ($1,000)
n = 3
r2 = 0.93
10
Acres
100
7-8
BMP Costs
ii ,
Li,. L
ih li'.llf
-------
Coal Remining BMP Guidance Manual
Table 7g: Daylighting
Mine
PA (6)
PA(1)
PA (7)
PA (11)
PA (9)
PA (3)
Acres
3 Day lighted
5.0
3.6
15.1
23.7
103.5
90
Recoverable
Coal
(1,000 tons)
9.72
8.957
26.550
47.988
229.767
550.785
Cost/Ton
of
Recovered
Coal
$0.25
$1.21
$ 1.54
$ 1.67
$2.00
$ 1.21
Cost (Date)
$ 2,430 ( 9/89)
$ 10,880 ( 4/90)
$ 40,770 ( 10/89)
$79,988 ( 10/93).
$ 459,534 ( 8/94)
$ 666,450 (12/88)
Cost
ENR 6000
($1,000)
$3.13
$ 13.91
$ 52.52
$91.17
$ 508.33
$ 875.37
1 Complete
2 Partial.
Assumptions:
Mining ratio cannot exceed 18:1 or 60 ft max. Highwall
60 ft. Max. Highwall
Cost Equation:
Least Squares Best Fit Linear Regression expressed as y = axb, (ENR=6000):
Equation:
Daylighting
1,000 -
ง 100 -
it
8 10-
o
1 -
1
ENฃ = 6000
^fl^JL'l-^
:'.' "' - ฃ, *''*ฃ
rr. v "_ ^
" ^" ^ ttaTB- ^ " "" 4
-i^x^ " -'
-*" " v^^
w--, 7^ <^ *4"' *
^^Vv^
../X\^i
^ '" "v.^
^ ?. *! ^ J 4
10 100 1,000
Tons of Coal Recovered (1,000)
y = 0.60xL21
where: x = Tons of
Recov. Coal
(1,000)
y = Cost ($1,000)
n = 6
r2 = 0.91
BMP Costs
7-9
-------
Coal Remining BMP Guidance Manual
Table 7h: Diversion Ditch
f
ii"
I
Mine
TN(5)
Length (Ft)
8751
Design Flow
(cfs)
195
Cost (Date)
$ 7,925 (5/94)
Cost
ENR60QO
$ 8,797
Unit Cost
ENR6000
($/Ft.)
$10.05
1 Estimated.
II:. ;,:
Assumptions:
Bottom Width
Side Slopes
Ditch Slope
Constructed Depth
Flow Depth (Design)
Lining
20'
2H:1V
1%
3'
1.85'
Rip rap for a 2.25' flow depth
Cost Equation: Not developed, only one point available.
f'i;
I
7-10
BMP Costs
- '., ',( i:
-------
Coal Remining BMP Guidance Manual
Table 7i; Diversion Wells, Alkalinity Producing
Reference
McClintock, 1993
Materials
$ 5,000
Labor ">
$ 6,000
TotaIซCostENปtfdOO
$ ll,000ea.
Assumptions:
From page ten of the reference: "A rough estimate is about $5,000 for the materials and
equipment rental."
From page 7 of the reference;" About 8 to 10 people working 8 hour per day for 2 to 3
days are needed for construction of a diversion well."
(10 people x 8 hours/day x 3 days x $ 25.00/hr = $ 6,000)
Cost Equation: Not developed, only one point available.
BMP Costs
7-11
-------
Coal Remining BMP Guidance Manual
Table 7j: Drains, Pit Floor
Mine
PA (8)
Total Length
(Ft)
2,600
Cost (Date)
$ 132,500 (2/93)
Unit Cost
ENR6000
($/Ft.)
$60.31
Assumptions:
Details not available in permit file.
Cost Equation: Not developed, only one point available.
7-12
BMP Costs
-------
Coal Remining BMP Guidance Manual
Table 7k: Regrading of Abandoned Mine Spoil/Highwalls
Mine
PA(7)
PA (10)
PA (11)
KY(4)
PA (6)
PA (5)
PA (19)
PA (3)
PA (18)
PA (9)
WV(4)
KY(3)
WV(9)
WV(7)
WV (10)
WV(2)
Cubic Yards -
(1,000)
76.550
138.905
304.944
332.046
136.660
178.100
321.376
1,090.613
4,000
7,743
3,630
17,250.378
5,488.314
5,848
7,139
12,100
Cost/cu.yd.
$0.16
$0.25
$0.16
$0.23
$0.65
$0.75
$0.50
$0.90
$0.65
$0.45
$1.00
$0.23
$1.00
$ 1.00
$ 1.00
$1.00
Cost (Date)
$ 12,060 (10/89)
$ 34,171 ( 2/90)
$48,150(10/93)
$ 76,039 ( 9/94)
$ 88,829 ( 9/89)
$ 133,575 ( 9/94)
$ 160,688 (12/97)
$981,552(12/88)
$ 2,600,000 (9/97)
$ 3,484,350 (8/94)
$ 3,630,000 ( 2/90)
$ 3,950,378 ( 8/91)
$5,488,314(10/81)
$ 5,848,000 ( 9/83)
$ 7,139,000 ( 3/85)
$12,100,000(1981)
Cost ENR 6000
($ liQOO)
$ 15.545
$ 43.76
$ 54.88
$83.91
$114.42
$ 147.76
$ 164.58
$ 1,289.25
$ 2,666.21
$ 3,854.37
$ 4,648.88
$4,845.11
$ 8,997.24
$ 8,471.27
$ 10,318.96
$ 20,537.48
Assumptions:
ป Regrading of abandoned mine spoil
" Elimination of abandoned highwalls
Cost Equation:
Least Squares Best Fit Linear Regression expressed as y = axb, (ENR=6000):
0
0
o^
ซ-
U)
o
$100,000
$1 0,000
-j '-"- I'i
- ! r 1 , ,*.
***~^* *-;<;
- J^^
*^*^ * O-
fc
NR=6000
ซ,.*. ^^wl^, ^ ^ ^ ^
^,v f
'1-
"""- -
' ^
A .; !
10.00 100.00 1,000.00 10,000.00 100,000.00
Cubic Yards (1,000 cu. yd.)
Equation:
y=0.136x
where: x
y
1.217
= Cu.Yds.
(1,000)
= Cost
($1,000)
n= 16
r2
'MP Costs
= 0.92
7-13
-------
: f|
Coal Remining BMP Guidance Manual
1
Table 71: Revegetation
Mine
PA (7)
PA (10)
KY(4)
PA (6)
VA(6)
PA(ll)
PA (8)
PA (19)
PA (4)
KY(1)
PA (18)
KY(3)
Acres
10
13
23.4
17
15
25.2
21
30.3
45
195.7
500
1,215.7
Cost/Acre
$450
$550
$409
$600
$750
$450
$720
$650
$800
$625
$ 1,000
$409
Cost (Date)
$4,500(10/89)
$7,150(2/90)
$ 9,570 ( 9/94)
$ 10,200 ( 9/89)
$11,250(10/91)
$ 11,340(9/89)
$ 16,200 (12/94)
$ 19,695 (12/97)
$ 36,000 ( 2/93)
$ 69,264 ( 7/97)
$ 500,000 ( 9/97)
$ 497,221 (8/91)
Cost ENR 6000
($ 1,000)
$5.80
$9.16
$10.56
$ 13.14
$ 13.80
$ 14.61
$ 17.87
$20.17
$ 42.60
$ 69.60
$512.73
$ 609.84
Assumptions:
Lime
Fertilizer
Seed
Mulch
Handling and spreading of above.
Cost Equation:
Least Squares Best Fit Linear Regression expressed as y = axb, (ENR=6000).
ซ' i ' '" ''I'*! '
ill' '"
_ $1,000
0*
0
5 $100
I $10
o
O
$1
;! 1
Revegetation
I 7=0.772^
: iซ=0.96
4nn ppp inn inn n in ipwiiipiiiii i iiiipnn iiiinili
4
i
>^
f*
^^
ENR=6006
i
'-
10 100 1,000 10,000
Acres
Equation:
; y = 0.772xฐ-961
where* x Aci
y = Coi
($1,0(
r2 = 0.96
n= 12
7-14
BMP Costs
-------
Coal Reminins BMP Guidance Manual
Table 7m: Sealing and Rerouting of Mine Water from Abandoned Workings
Mine
Lin. Ft.
(1000)
Cost/
Lin. Ft.
Clay
(Cu.Yd.)
Cost/
Cii.Yd;
Cost (Date)
Cost
ENR 6000
Highwall Seal
PA(1)
PA(3)
1.75
10.50
$4.69
$3.80
4,111
20,000
$ 2.00
$2.00
$ 8,222 ( 3/90)
$ 40,000 (12/88)
$ 10.52
$ 52.54
Clay Barrier
PA (10)
1.75
$0.67
583
$2.00
$ 1,166 ( 9/96)
$ 1.23
Auger Holes
KY(4)
KY(3)
1.88
11.16
$0.20
$0.20
1,671
9,920
$0.23
$0.23
$ 380 ( 9/94)
$2,275(8/91)
$0.42
$2.79
Assumptions:
Highwall Seal
10' - 12' at base
8' high
slope away from highwall face
Mine void to be filled with clay to a width and depth of a minimum of 3
times the diameter of the exposed opening.
Clay available on-site.
Clay Barrier
3' high
3' wide
Clay available on-site
Auger Hole Seals
4' high
6' wide
Clay available on-site
Cost Equations:
Least Squares Best Fit Linear Regression expressed as y = axb, (ENR=6000):
Highwall Seal ==> y = 6.37xa9ฐ where: x = Linear Feet (1,000)
y = Cost ($1,000)
Clay Barrier ==> y = 0.703x L0 where: x = Linear Feet (1,000)
y = Cost ($1,000)
Auger Hole Seal ==> y = 0.215xL06 where: x = Linear Feet (1,000)
y = Cost ($1,000)
r2=1.0
n = 2
r2=1.0
n = 2
BMP Costs
7-15
-------
Coal Remining BMP Guidance Manual
Table 7n: Silt Fences
j
ill'".
jh
r
L
(1
Source
Ref.(USEPA, 1992)
Unit Cost (Date)
$ 6.00/Ft. (1992)
Unit Cost
ENR 6000
($/Ft.)
$ 7.221
1 Installation costs only.
[', v ;ii - .. ; . . , ,,. i i ,. / ;
I;,1. '':' < ""M ' }" II ' .'.
Assumptions:
Silt fences are appropriate at the following general locations:
(1) Immediately upstream of point(s) of runoff discharge from a site before
flow becomes concentrated (maximum design flow rate should not
exceed 0.5 cubic feet per second).
(2) Below disturbed areas where runoff may occur in the form of overland
flow,
Ponding should not be allowed behind silt fences since they will collapse under
high pressure; the design should provide sufficient outlets to prevent overtopping.
The drainage area should not exceed 0.25 acre per 100 feet of fence length.
For slopes between 50:1 and 5:1, the maximum allowable upstream flow path
length to the fence is 100 feet; for slopes 2:1 and steeper, the maximum is 20 feet.
* The maximum up slope grade perpendicular to the fence line should not exceed
' ' ^ 1:1. "' i " ^ '_ 7 ' .'.
Synthetic silt fences should be designed for six months of service; burlap is only
acceptable for periods of up to 60 days.
(II,,, Ml,,, I, || , ,
Cost Equation: Not developed with only one point available.
7-16
BMP Costs
-------
Coal Remining BMP Guidance Manual
Table 7o: Special Handling for Toxic and Acid Forming Materials
Mine
PA (11)
PA (19)
PA (7)
PA (3) '
Cubic
Yards
(1,000)
17.58
15.81
216.13
2,468.4
Cost/cu.yd.
$0.20
$1.00
$0.25
$0.90
Cost (Date)
$ 3,516(9/89)
$ 15,811(12/97)
$ 54,032 ( 6/88)
$2,221,560 (12/88)
Cost
ENR 6000
($1,000)
$4.53
$16.19
$71.64
$2,917.99
Assumptions:
Material placed 25' above floor
Placed in 2' layers
Up to 30" clean fill in between
25 tons/acre of lime on top
. 25' from outcrops
4' clean cover
Cost Equation:
Least Squares Best Fit Linear Regression expressed as y = axb, (ENR=6000): _
y = 0.309x
1.129
where: x = Cubic Yards (1,000)
y = Cost ($1,000)
r2 = 0.94
n = 4
cT
ฃ
in
o
0
Special Handling
ENR = 6000
$10,000 -.
$1 nnn -
vf> 1 ,\J\J\J
$100 -
$10 -
$1 -I
.__ -f
1<~'. y"-...0 309>c1.:li$L?.
~*L ' r~ "-**^ ,.. ,
" ^ ' X i' __-
^ ~ ^ ^ i. _^*~~******'^
^ ^^N "" ^^ i
^ t f 1X ( t i i j^
- . -.._ ,. ,,
f , """-
7 * _^^^7~^
^~~~~~~~~" "
"~*~t~~" ^x r^ i -i<^i|;w-
^ '/ ' ^' ,_ r H *
> _ , "" ," ' X ~"
1* 1 % * 1 1 1 ) 1
: -- -r'/;r ^~-~3
_-^ ->, .,_ ^ ป j
7i '*, _j
ซ, *- ? / A. j
' c^ ^ ^* ""* 1
^c ^ s >! ^**
' ^ ~ \ , ,1
^ s^ ^
- - * " " * t -.* t r < v!
I
10 100 1,000 10,000
Cubic Yards (1,000 cu. yds.)
7-17
-------
Coal Remining BMP Guidance Manual
References
ENR, l999; Engineering New Record Construction Cost Index (1908-1999).
http://www.enncom/cost/costcci.asp, 2 p.
McClmtock, S.A., D.E. Arnold and A.J. Gaydos, 1993. An Installation and Operations Manual
for Diversion Wells: A Low Cost Approach for Treatment of Acidic Streams. Pennsylvania State
University, 23 p.
Ijr1 ;i sv ซ<)! ' , .'"...' i: :, , '' '' / ''i:!,:1!,
USEPA, 1992. Storm Water Management for Construction Activities, Office of Water, Report
No. EPA 832-R-92-005.
t .: ' ".'. ' .(! : : I I '.' ' : I. *
7-18
BMP Costs
-------
Coal Remining BMP Guidance Manual
Appendix A: EPA Coal Remining Database - 61 State Data
Packages
Appendix A
-------
Coal Remining BMP Guidance Manual
Appendix A
-------
Coal Remining BMP Guidance Manual
APPENDIX A:
EPA Coal Remining Database - 61 State Data
Packages
Information Collection
In an effort to assess the implementation of Best Management Practices during remining and
reclamation activities in the Eastern United States, the EPA requested that the Interstate Mining
Compact Commission (IMCC) collect information from stakeholder States involved in the IMCC
Remining Task Force. The information was to support EPA's efforts to propose a coal remining
subcategory under 40 CFR part 434. The goal of the information request was to collect existing
information and data for assessment of the benefits, limitations, and feasibility of maintaining or
improving environmental quality during and after remining operations. IMCC specifically
requested information on abandoned mine land conditions, BMP implementation plans, water
quality data, cost information, production statistics, and remining operations.
Six states (Alabama, Kentucky, Pennsylvania, Tennessee, Virginia, and West Virginia)
responded to the request for information and submitted a total of 61 individual data packages
from remining operations and reclamation projects. The data and information were submitted to
EPA and were used to develop this BMP Guidance Manual in support of proposal of a Remining
subcategory. Details of the types of information and data collected are provided in Table A. 1.
Data and information submitted included permits, permit applications, water quality monitoring
reports, inspection reports, bore hole analysis logs, and operational information.
Appendix A
A-l
-------
Coal Remining BMP Guidance Manual
, !
A-2
Appendix A
-------
Coal Remining BMP Guidance Manual
Table A.I: Data Targeted by EPA Information Request
Water Quality / Environmental Benefits
Environmental Assessment
Abatement Plans
Impact Statistics: Abandoned Surface Mine acres affected
Abandoned Underground Mine acres affected
Abandoned Highwall linear feet affected/removed
Pre-existing discharges encountered/affected
Stream Miles degraded by AMD (EPA 303(d) list)
Industry Profile - by State
Number of companies
Number of mine sites
Types of mining activities
Production statistics
Permit Applications
Permits
Environmental Resources Maps
Geology Information
Overburden Analyses
Borehole Analyses
Hydrologic Assessment
Chemical Analysis (Background Monitoring Reports - Concentration)
(Flow, pH, Conductivity, Temp., Alkalinity, Acidity, Fe, Mn, Al, SO4, TSS/TDS)
Ground Water Information
Surface Water Information
Pre-existing Discharge Information
Public Water Supply Information
Operational Information
Reclamation/Operation Description and Maps
Reclamation Cost Estimate / Time Schedule
Identification of Final Grading and Drainage Pattern
Production Statistics
Annual and overall coal production (tonnage)
Annual and overall profit
Number of employees
Cost Information
Cost of BMP implementation versus cost of treatment (pre-existing discharges)
Appendix A
A-3
-------
Coal Remining BMP Guidance Manual
Best Management Practices (BMPs) - descriptions/typical combinations
Regrading
Daylighting
Management of toxic and acid forming materials
Addition of alkaline materials
Hydrologic controls: diversion ditches, mine seals, hydraulic barriers
Revegetation
Stabilization
Application of Biosolids
Remining Plans
Identification of Affected Abandoned Mine Areas, Highwalls, and Preexisting Discharges
Background History of Preexisting Discharges
Baseline Pollution Load Analysis and Data
Abatement Plan / BMP Application and Description / BMP Implementation Costs
Water Quality Monitoring Program
Anticipated Pollution Reduction Benefits - Impact on Water Quality - Benefits
Treatment Costs Schedule
Topographic Maps
Remining Database
All data submitted for the 61 mining and reclamation operations has been entered into EPA's
Remining Database, 1999, which was designed specifically to contain the data and information
provided in these data packages, the database design is shown in Figure A-l. The final version
of the database (May, 1999) is available on CD-ROM from EPA's Sample Control Center, and
can be requested by calling the Sample Control Center at 703/461-2025. The CD-ROM is
accompanied by the Coal Remining Database User's Manual and Database Data Element
Dictionary.
The Remining Database contains both qualitative and quantitative data. Because not all solicited
information was available or applicable to all 61 sites, some database fields are empty. Numeric
data is provided in the geology, surface water, ground water, and mine discharge sections of the
database and was entered as was reported by the States. The narrative information was taken
from the mine site permits, permit applications, abatement plans, or related information.
A-4
Appendix A
-------
Coa/ Remining BMP Guidance Manual
Figure A.I: EPA Remining Database Design
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A-5
-------
CoetZ Risminmg BMP Guidance Manual
Figure A.I: EPA Remining Database (continued)
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Appendix A
-------
Coal Remining BMP Guidance Manual
Figure A.I: EPA Remining Database (continued)
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-------
Coal Remining BMP Guidance Manual
Information Summary
A summary of the information is given in the following tables.
Table A.2: According to the information provided by the data packages and
subsequent contact responses, 30 of the 61 operations were closed as of
the date the data were submitted. Mine closure dates for mines that are
known to be closed, are included in Table A.2.
Table A.3: Contains information on the extent and type of abandoned mine land and
the extent the abandoned mine land was expected to be affected by
remining operations.
Table A.4: Contains the type of mining or reclamation operations and the coal seams
mined for each site. In some cases, a remining operation involved
reclamation of abandoned spoils piles and no coal seams"were mined.
Table A.5: Lists the BMPs implemented during remining or reclamation activities.
The BMPs are listed in the order presented in this document with the mine
sites that implemented each BMP.
Table A.6: Lists the BMPs implemented during remining or reclamation activities.
The BMPs are organized by the mine sites which implemented them.
Appendix A
A-9
-------
l>
, n,'!,,;1
Coal Remitting BMP Guidance Manual
If::,;
J!
f'Uft
A-10
Appendix A
-------
Coal Remining BMP Guidance Manual
Table A.2: Mine Site Status and Permit Information
Mine ID
AL(1)
AL(2)
AL(3)
AL(4)
AL(S)
AL(6)
AL(7)
AL(8)
AL(9)
AL(10)
AL(ll)
AL(12)
AL(13)
AL(14)
AL(15)
AL(16)
KY(1)
KY(2)
KY(3)
KY(4)
PA (1)
PA(2)
PA(3)
PA(4)
PA(5)
PA(6)
PA(7)
PA(8)
PA(9)
PA(10)
PA(ll)
PA(12)
PA(13)
PA(14)
PA{15)
PA(16)
PA(17)
PA(18)
PA(19)
TN(1)
TNC2)
Issuance Date
07/05/1983
08/24/1989
09/11/1989
12/06/1989
03/16/1990
09/19/1990
03/06/1991
06/03/1992
06/09/1992
03/08/1994
Unknown
07/30/1991
01/23/1991
12/08/1986
01/28/1988
Unknown
07/18/1997
09/19/1997
08/13/1991
04/04/1995
04/02/1991
05/23/1989
05/25/1990
04/13/1988
02/01/1995
04/13/1990
09/15/1989
09/01/1993
; Unknown
11/06/1990
04/25/1990
05/11/1992
02/24/1989
08/24/1987
03/15/1985
06/01/1992
02/12/1990
12/12/1996
12/23/1997
01/24/1992
07/25/1980
07/04/2003
08/23/1994
09/10/1999
12/05/1999
.03/15/2000
09/18/1995
03/05/1996
06/02/1999
06/08/1997
03/07/1999
Unknown
Unknown
Unknown
Unknown
01/27/1993
Unknown
07/18/2002
09/19/2002
09/13/1994
08/31/2002
04/02/2001
05/23/1999
05/25/1995
04/13/2003
02/01/2000
04/13/2000
09/15/1999
09/01/1998
Unknown
11/06/1995
04/25/2000
05/11/2000
06/13/1999
08/24/2002
03/15/2000
06/01/2002
02/12/2000
12/12/2001
12/23/2002
Unknown
07/25/1981
Active Site
Early 1991
08/18/1998
Active Site
10/1995
08/1994
07/17/1992
Active Site
03/1994
02/1996
Mining Suspended
12/01/1998
10/10/1994
Early 1990
Permitted, but never mined
Reclaiming
Active
Active
Shut down 1 1/1998, may reopen
Active
10/30/1998
Active
06/23/1998
Active
04/09/1998
08/15/1996
05/01/1996
Active
Active
1 1/06/1995
Active
Active
Unknown
Active
Active
Active
Active
Active
Active
Active
Bond returned by State, 1984
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
.Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Appendix A
A-ll
-------
Coal Remining BMP Guidance Manual
Mine ID
TN(3)
TN(4)
TN(5)
VA(1)
VA(2)
VA(3)
VA(4)
VA(5)
VA(6)
VA(7)
VA(8)
VW(1)
WV(2)
WV(3)
WV(4)
WV(5)
WV(6)
\W(7)
WV(8)
WV(9)
wvrio)
Issuance Date
05/08/1997
11/22/1996
12/16/1991
12/05/1994
10/03/1990
01/16/1988
None
None
01/16/1992
06/20/1990
09/27/1996
Unknown
10/16/1987
Unknown
02/21/1990
01/06/1994
03/26/1985
09/23/1983
08/05/1993
10/01/1981
03/25/1985
Expiration Date
Unknown
06/27/1998
Unknown
07/24/2002
Unknown
Unknown
None
None
Unknown
Unknown
Unknown
Unknown
09/14/1992
07/14/1999
01/16/2003
01/06/1999
01/10/2000
09/23/1988
08/05/1998
09/14/1997
03/25/1990
Mine Closure Date
04/09/1998, Phase I Bond Release Only
Active
12/16/1994, Bond Forfeited
10/05/1998
12/07/1993
12/12/1997
Closed
Closed
Active
Active
Active
Active
12/05/1991
Active
11/1 6/1995, Phase I only
Active
Active
11/26/1991
Active
03/10/1997
07/10/1996
Rahall Permit
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
No
Yes
No
Yes
Yes
No
Yes
No
No
A-12
Appendix A
-------
Coal Remining BMP Guidance Manual
Table A.3: Extent of Abandoned Mine Lands
Mine ID
AL(1)
AL(2)
AL(3)
AL(4)
AL(5)
AL(6)
AL(7)
AL(8)
AL(9)
AL(10)
AL(ll)
AL(12)
AL(13)
AL(14)
AL(15)
AL(16)
KY(1)
KY(2)
KY(3)
KY(4)
PA(1)
PA(2)
PA(3)
PA(4)
PA(5)
PA(6)
PA(7)
PA(8)
PA(9)
PA(10)
PA(ll)
PA(12)
PA(13)
PA(14)
PA(15)
PA(16)
PA(17)
PA(18)
PA(19)
TN(1)
ADM1
(Acres)
0
0
0
0
0
0
0
36.1
29.8
56.5
90
81.8
0
28.3
27.2
128.9
0
66.1
0
0
2725
0
Affected ADM
("Acres)
0
0
0
0
0
0
0
36.1
3.6
0
49
0
0
5
27.2
103.5
0
23.7
0
640
0
ASM2
(Acres)
21
64
18
9
186.7
246.4
181
186.1
0
50
69.9
43.8
77.4
24.8
0
187.4
32.2
65
311
729.7
650
29.3
Affected
ASM (Acres)
18
9
186.7
246.4
181
186.1
0
50
33.8
43.8
63.9
15.5
0
187.4
15.6
37.8
311
60.6 to 678
500
3
AH3
(feet)
0
0
0
0
0
0
1100
2600
35; 50
0
11,788
2150
61730
106,350
1450
AH Removed
(feet)
0
0
0
o-
0
0
1100
1700
0
11,788
1800
10880 to 61730
52,300
1450
Appendix A
A-13
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Coal Remininz BMP Guidance Manual
Mine ID
TN(2)
TN(3)
TN(4)
TN(5)
VA(1)
VA(2)
VA(3)
VA(4)
VA(5)
VA(6)
VAC7)
VA(8)
WV(1)
WV(2)
WV(3)
WV(4)
WV(5)
WV(6)
WV(7)
WV(8)
WV(9)
WV(10)
ADM1
(Acres)
252.19
0
94
Affected ADM
(Acres')
0
94
ASM2
(Acres)
265
37.4
105
590
1140.25
1440
67
92
54
Affected
ASM (Acres)
485.19
1140.25
1440
67
92
54
AH3
(feet)
2,400
13,000
8400
17.832
AH Removed
(feet)
12000
Note: Blank cells indicate that no mention was made of the existence of that type of abandoned mine
land. Zeros are used in the table to show that the mining operator specifically mentioned that the
type of abandoned mine land was not present or affected.
'Abandoned deep mine
Abandoned surface mine
3Abandoned highwall
A-I4
Appendix A
SJI"
-------
Coal Remining BMP Guidance Manual
Table A.4: Type of Mining and Coal Seams Mined
Mine ID
AL(1)
AL(2)
AL(3)
AL(4)
AL(5)
AL(6)
AL(7)
AL(8)
AL(9)
AL(10)
AL(ll)
AL(12)
AL(13)
AL(14)
AL(15)
AL(16)
KY(1)
KY(2)
KY(3)
KY(4)
PA(1)
PA(2)
PA(3)
Coal Seams Mined
Jefferson and Lick Creek
Suwanee
Blue Creek and Jefferson
Black Creek
Pratt Group
Black Creek and Jefferson
Utley Coal Group
Mary Lee
Atna, Cliff, and Underwood
Guide, Upper Brookwood, Lower
Brookwood, Milldale, Carter, and Johnson
Unknown
Pratt, Nickel Plate, and America
Guide, Brookwood, Upper Milldale, Lower
Milldale, and Carter
None
Unknown
None
None
Amburgey, Hazard No. 4, Hazard No.4 Rider,
Hz #7, Hz A, and Whitesburg
USGS #11, USGS #12, and USGS #13
USGS #11, USGS #12, USGS #13, USGS
#14, and USGS #9
Lower Freeport, Upper Freeport, and Upper
Freeport Rider
USGS #11
Pittsburgh
Type of mining
Surface Mining
Surface Mining
Surface Mining
Surface Mining
Surface Mining
Bituminous and Surface Mining
Surface Mining
Surface Mining
Surface Mining
Auger Mining and Surface Mining
Bituminous and Surface Mining
Bituminous and Surface Mining
Surface Mining
Bituminous, Surface Mining, and Coal Refuse
Disposal
Bituminous and Surface Mining
Coal Preparation Plant and Surface Mining
Coal Refuse Reprocessing; Surface Mining, and
Remining
Surface Mining, Auger Mining, and Remining
Auger Mining, Refuse Storage, and Surface Mining
Auger Mining and Surface Mining
Bituminous, Surface Mining, and Reclamation
Operations
Bituminous, Coal Refuse Reprocessing, Fly
Ash/Bottom Ash Disposal, and Surface Mining
Bituminous and Surface Mining
Appendix A
A-15
-------
ll'i,,: i1:,, p1,,1!! '
Coal Remining BMP Guidance Manual
Mine ID
PA(4)
PA(5)
PA(6)
PA(7)
PA(8)
PA(9)
PA(10)
PA(ll)
PA(12)
PA(13)
PA(14)
PA(15)
PA(16)
PA(17)
PA(18)
PA(19)
TN(1)
TN(2)
A-16
Coal Seams Mined
Pittsburgh
Lower Kittanning and Middle Kittanning
Upper Freeport
Boney, Lower Freeport, Upper Freeport, and
Upper Kittanning
Lower Kittanning and Middle Kittanning,
Lower Freeport, Lower Kittanning, Middle
Kittanning, and Upper Kittanning
Lower Bakerstown
Lower Freeport, Upper Freeport, and Upper
Kittanning
Upper Freeport
Lower Freeport, Lower Kittanning, Middle
Kittanning, and Upper Kittanning
None
Buck Mountain, Holmes, Mammoth Bottom,
Mammoth Top, Orchard, Primrose, Seven
Foot Vein, and Skidmore
Buck Mountain, Holmes, Little Buck
Mountain, Mammoth Bottom, Mammoth Top,
Seven Foot Vein, and Skidmore
Bottom Split Mammoth Vein, Diamond Vein,
Holmes, Middle Split, Mammoth Vein,
Primrose, Seven Foot Vein, and Skidmore
Holmes, Mammoth, and Primrose
Lower Kittanning No. 2 and Lower
Kittanning No. 3
Blue Gem, Coal Creek, and Jellico
Sewanee
'!' '= ::'
Type of mining
Bituminous, Coal Refuse Reprocessing, and
Remining
Bituminous and Surface Mining
Auger Mining, Bituminous, Remining, and Surface
Mining
Auger Mining, Coal Refuse Disposal, and Surface
Mining
Surface Mining
Mobile Coal/ Rock Processing, Remining, and
Surface Mining
Remining and Surface Mining
Auger Mining, Bituminous, and Surface Mining
Auger Mining, Bituminous, Coal Refuse
Reprocessing, Fly Ash/Bottom Ash Disposal, and
Surface Mining
Auger Mining, Bituminous, and Surface Mining
Anthracite, Coal Preparation Plant, Coal Refuse
Disposal, Coal Refuse Reprocessing, and Fly
Ash/Bottom Ash Disposal
Anthracite and Surface Mining
Anthracite, Coal Refuse Disposal, Coal Refuse
Reprocessing, and Surface Mining
Anthracite, Coal Refuse Disposal, Remining, and
Surface Mining
Anthracite, Coal Refuse Disposal, Coal Refuse
Reprocessing, Fly Ash/Bottom Ash Disposal,
Reclamation Operations, and Remining
Remining and Surface Mining
Auger Mining and Surface Mining
Surface Mining
'": .'..':'
Appendix A
-------
Coal Remining BMP Guidance Manual
Mine ID
TN(3)
TN(4)
TN(5)
VA(1)
VA(2)
VA(3)
VA(4)
VA(5)
VA(6)
VA(7)
VA(8)
WV(1)
WV(2)
WV(3)
WV(4)
WV(5)
WV(6)
WV(7)
WV(8)
WV(9)
WV(10)
Coal Seams Mined
Sewanee
Sewanee
Coal Creek
Clintwood, Lower Boiling, Lower Standiford,
Meade Fork, Pinhook, Upper Boiling, and
Upper Standiford
Lower Clintwood, Middle Clintwood, and
Upper Clintwood
Blairs, Clintwood, Dorchester, Lyons, and
Norton
No Seams Mined
No Seams Mined
Bastard Seam, Cedar Grove, Housecoal,
Imboden Marker, Jackrock, Low Splint,
Lower Kelly, Lower Standiford, Owl,
Taggart, Taggart Marker, and Upper
Standiford
Bottom Taggart, Cedar Grove, Imboden
Marker, Kelly Rider, Lower Kelly, Lower
Standiford, Owl, Taggart Marker, Top
Taggart, Upper Kelly, and Upper Standiford
Clintwood
Clarion, Lower Kittanning, Lower Mercer,
Middle Kittanning, and Upper Mercer
Upper Freeport
Bakerstown, Brush Creek, Harlem, and Upper
Freeport
Castle and Sewell
Upper Freeport
Upper Freeport
Pittsburgh and Redstone
Pittsburgh
Big Inch, Little Pittsburgh, and Morantown
Unknown
Type of mining
Deep Mining Reclamation and Surface Mining
Auger Mining and Surface Mining
Reclamation Operations
Auger Mining, Remining, and Surface Mining
Auger Mining, Bituminous, Remining, and Surface
Mining
Auger Mining, Remining, and Surface Mining
Reclamation Operation
Reclamation Operation
Bituminous, Remining, and Surface Mining .
Surface Mining
Surface Mining
Deep Mining Reclamation, Remining, Surface
Mining, and Underground Mining
Auger Mining and Surface Mining
Fly Ash/Bottom Ash Disposal, Remining
Modification, and Surface Mining
Surface Mining
Fly Ash/Bottom Ash Disposal and Surface Mining
Fly Ash/Bottom Ash Disposal and Surface Mining
Surface Mining
Deep Mining Reclamation, Fly Ash/Bottom Ash
Disposal, and Surface Mining
Reclamation Operations and Surface Mining
Surface Mining
Appendix A
A-17
-------
Coal Remitting BMP Guidance Manual
A-18
Appendix A
-------
Coal Remining BMP Guidance Manual
Table A.5: BMPs and the mines that implemented them
BMP
Mine ID
Exclusion of Infiltrating Surface Water
Regrading Abandoned Mine Spoil
Installation of Surface Water Diversion
Ditches
Low-Permeability Caps or Seals
Revegetation
Stream Sealing
All mines
AL(1), AL(3), AL(4), AL(5), AL(ll), KY(3), TN(5),
VA(1), VA(4), VA(6), WV(1), WV(5), WV(6), WV(8)
VA(5)
All mines
None
Control of Infiltrating Ground Water
Daylighting of Underground Mines
Sealing and Rerouting of Mine Water
from Abandoned Workings
Highwall Drains
Pit Floor Drains
Grout Curtains
Ground Water Diversion Wells
AL(12), KY(2), PA(1), PA(3), PA(6), PA(7), PA(8), PA(9),
PA(ll), PA(12), PA(17), PA(18), TN(3), VA(1), VA(7),
VA(8), WV(1), WV(2)
KY(3), KY(4), PA(1), PA(3), PA(10), TN(3), TN(4), VA(6)
None
TN( 1 ), TN(2), TN(3), TN(5), VA(6), VA(8)
None
None
Sediment control
Site Stabilization
Channel, Ditch, and Gulley Stabilization
Check Dams
TN(4), VA(6)
None
None
Geochemical Best Management Practices
Alkaline Addition
Special Handling of Acid Forming
Materials
Bactericides/ Anionic Surfactants
Passive Treatment
PA(1), PA(2), PA(8), PA(10), PA(ll), PA(12), PA(14),
PA(17), PA(18), PA(19), TN(3), TN(4), TN(5), WV(1),
WV(3), WV(5), WV(6), WV(8)
AL(1), AL(2), AL(7), AL(10), AL(ll), AL(14), KY(1),
KY(2), KY(3), KY(4), PA(3), PA(5), PA(6), PA(7), PA(8),
PA(ll), PA(13), PA(14), PA(19), TN(1), TN(2), TN(4),
VA(1), VA(2), VA(3), VA(4), VA(6), VA(7), WV(1),
WV(4), WV(5), WV(6), WV(7), WV(8), WV(9)
PA(10), VA(4)
TN(2), TN(3), TN(5), VA(4), VA(8), WV(5)
Appendix A
A-19
-------
Coal Remining BMP Guidance Manual
!! ' It'"
X
II;
A-20
Appendix A
-------
Coal Remining BMP Guidance Manual
Table A.6: Mines and the BMPs implemented
Mine ID
AL(1)
AL(2)
AL(3)
AL(4)
AL(5)
AL(6)
AL(7)
AL(8)
AL(9)
AL(10)
AL(ll)
AL(12)
AL(13)
AL(14)
AL(1S)
AL(16)
KY(1)
KY(2)
KY(3)
KY(4)
PA(1)
PA(2)
BMPs Implemented
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches
Regrading Abandoned Mine Spoil, Revegetation
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation
Regrading Abandoned Mine Spoil, Revegetation
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines
Regrading Abandoned Mine Spoil, Revegetation
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation
Regrading Abandoned Mine Spoil, Revegetation
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming
Materials, Daylighting of Underground Mines
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches, Sealing and Rerouting of Mine Water from Abandoned Workings, Special Handling
of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Sealing and Rerouting of Mine Water from
Abandoned Workings, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Sealing and Rerouting of Mine Water from
Abandoned Workings, Alkaline Addition, Daylighting of Underground Mines
Regrading Abandoned Mine Spoil, Revegetation, Alkaline Addition
Appendix A
A-21
-------
Coal Remining BMP Guidance Manual
Mine ID
PA(3)
PA(4)
PA(5)
PA(6)
PA(7)
PA(8)
PA(9)
PA(10)
PA(ll)
PA(12)
PA(13)
PA(14)
PA(15)
PA(16)
PA(17)
PA(18)
PA(19)
TN(1)
TN(2)
TN(3)
BMPs Implemented
Regrading Abandoned Mine Spoil, Revegetation, Sealing and Rerouting of Mine Water from
Abandoned Workings, Daylighting of Underground Mines, Special Handling of Acid
Forming Materials
Regrading Abandoned Mine Spoil, Revegetation
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines,
Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines,
Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines,
Alkaline Addition, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines
Regrading Abandoned Mine Spoil, Revegetation, Sealing and Rerouting of Mine Water from
Abandoned Workings, Bactericides/ Anionic Surfactants, Alkaline Addition
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines,
Alkaline Addition, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines,
Alkaline Addition
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Alkaline Addition, Special Handling of
Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation
Regrading Abandoned Mine Spoil, Revegetation
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines,
Alkaline Addition
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines,
Alkaline Addition
Regrading Abandoned Mine Spoil, Revegetation, Alkaline Addition, Special Handling of
Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Pit Floor Drains, Special Handling of Acid
Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Pit Floor Drains, Special Handling of Acid
Forming Materials, Passive Treatment
Regrading Abandoned Mine Spoil, Revegetation, Pit Floor Drains, Daylighting of
Underground Mines, Special Handling of Acid Forming Materials, Sealing and Rerouting of
Mine Water from Abandoned Workings, Alkaline Addition, Passive Treatment
A-22
Appendix A
1 :!';
-------
Coal Remining BMP Guidance Manual
Mine ID
TN(4)
TN(5)
VA(1)
VA(2)
VA(3)
VA(4)
VA(5)
VA(6)
VA(7)
VA(8)
WV(1)
WV(2)
WV(3)
WV(4)
WV(5)
WV(6)
WV(7)
WV(8)
WV(9)
WV(10)
BMPs Implemented
Regrading Abandoned Mine Spoil, Revegetation, Sealing and Rerouting of Mine Water from
Abandoned Workings, Alkaline Addition, Special Handling of Acid Forming Materials, Site
Stabilization
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion,
Ditches, Pit Floor Drains, Alkaline Addition, Passive Treatment
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines,
Installation of Surface Water Diversion Ditches, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches, Special Handling of Acid Forming Materials, Bactericides/ Anionic Surfactants,
Passive Treatment
Regrading Abandoned Mine Spoil, Revegetation, Low-Permeability Caps or Seals
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches, Sealing and Rerouting of Mine Water from Abandoned Workings, Special Handling
of Acid Forming Materials, Site Stabilization, Pit Floor Drains
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines, Special
Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines, Pit
Floor Drains, Passive Treatment
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines,
Alkaline Addition, Installation of Surface Water Diversion Ditches, Special Handling of Acid
Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Daylighting of Underground Mines
Regrading Abandoned Mine Spoil, Revegetation, Alkaline Addition
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches, Alkaline Addition, Passive Treatment, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches, Alkaline Addition, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Installation of Surface Water Diversion
Ditches, Alkaline Addition, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation, Special Handling of Acid Forming Materials
Regrading Abandoned Mine Spoil, Revegetation
Appendix A
A-23
-------
jj-vCoa/ Remitting BMP Guidance Manual
it-1"
fr
k ' ' '>:'
111* ,,!'i
,,,(!!. " 'i
A-24
Appendix A
-------
Coal Remining BMP Guidance Manual
Appendix B: Pennsylvania Remining Site Study
Appendix B
-------
I >
Coal Reminlng BMP Guidance Manual
y , :
nil, ii|<'" i
;Mil.
Appendix B
-------
Coal RemininK BMP Guidance Manual
Appendix B: Pennsylvania Remining Site Study
The Pennsylvania Department of Environmental Protection (PA DEP) has been issuing renaming
permits since 1984. By 1997, over 260 remining permits had been issued throughout
Pennsylvania. This number includes currently active and reclaimed sites. PA DEP routinely
reviews self-monitoring reports from these permits to verify that water quality loading limits
have not been exceeded. On an annual basis and for all bond release applications, the baseline
pollution load is compared to recent pollution load data using a statistical protocol for
determining whether there has been a significant increase in the baseline pollution load. If the
analysis shows a statistically significant increase in the baseline pollution load, then the operator
is required to treat the discharge to at least its original baseline loading rate and reclamation
bonds are withheld until the discharge returns to baseline levels or below. Over 10 years of
experience shows that baseline excedences are a very rare occurrence. Of these 260 permits,
only 5, or less than 2 percent, have ever registered significant increases from baseline pollution
load, requiring long-term treatment. In 1998, PA DEP developed a remining database to
determine the success of Pennsylvania's remining program in terms of water quality compliance,
and the extent to which remining has reduced pollution loads from pre-existing mine discharges.
These evaluations were made by comparing pre-mining and post-mining loads at individual pre-
existing discharges for acidity, iron, manganese, aluminum, sulfate, and flow. Additionally, the
data were broken down by best management practices (BMPs) that were implemented
hydrologically upgradient from each discharge to allow evaluation of the efficiencies of
individual and combined BMPs.
The database consists of 241 groundwater discharges (or hydrologic units) from 112 mine sites
that were used for statistical analysis. These discharges are hydrologically connected to the
mining and reflect the effects of the upgradient remining. Only mines that were Stage n bond
released (completely backfilled and revegetated) were included. The sites in the database were
further restricted to Pennsylvania's Bituminous Coal Field. This restriction was made because
(1) the geology, hydrology, mining methods, and some of the BMPs in the Anthracite Region are
substantially different from the Bituminous Region, (2) the Bituminous Region has had a much
Appendix B B-l
-------
Cgg/ Remining BMP Guidance Manual
greater number of remining permits issued and for a longer period of time, and (3) the
Bituminous Region has geology, hydrology, mining methods, and BMPs similar to the rest of the
Appalachians. The distribution of mine sites and discharges in the database are depicted by
lifjiii , ;;1= ;S ?>] . ""' , * ''" ' ::i '.-' J.;';.:W. . ;;;! ..','.; I"'!K'iJ.''* $': w. -
county on Figure B.I. As can be seen, reminmg sites are spread across the Bituminous Region.
"i;;. N: ',. "i3,,, ;J* m ; + A* !.;!,'] : '' '", ' " ป : >ii: 'I: ''Ihi1' ".I.;:!,; ..':' : :'^'- : "I '=? ?'M':S,
The rejoining sites are surface mines, with the exception of six coal refuse removal sites. There
fcj ;", .' " <1; i:, !i. .' , :-;"" :'T " :" ? :':l ,, i i,}'11 ! "i/: ?",, ':':;'I" I' '<.''it T . '"' " ' 'V'1 i;
is a total of eight discharges associated with the coal refuse removal sites, compared to 233
discharges associated with surface mining.
The effluent limits which are typically established by best professional judgement (BPJ) analysis
are acidity, total iron, total manganese, and total aluminum. Load based BPJ limits are
established using baseline data. If water quality concentrations are below best available
technology (BAT) limits, then BAT limits are applied. Acidity and sulfate are the most common
post-mining pollutants from remining sites, thus their greater representation in the statistical
database (Table B.I) than for other pollutants. Iron, manganese, and aluminum to varying
i
degrees meet BAT requirements and therefore do not always undergo a BPJ analysis, thus their
less frequent representation in the database.
Acidity has been selected in Pennsylvania for BPJ analysis preferentially to pH because a
baseline load can be calculated for acidity, whereas pH does not readily lend itself to calculation
of load. Acidity includes "potential" acidity which is latent in "mineral" acidity, a form that is
Often not represented by pH. Mineral acidity is that portion of acidity that is generated when
iron, manganese, aluminum, and some other metals precipitate from solution (see equation 1,
Section 2.0). When determining the amount of chemical treatment needed to neutralize acid or
to bring the pH up to a certain level, it is acidity that is used to perform these calculations, not
pH. Acidity is in units of mg/L calcium carbonate, the same as used for alkalinity.
'N V
lii
B-2
Appendix B
-------
Coal Remining BMP Guidance Manual
Figure B.I Mine Sites and Discharges by County in Pennsylvania
o
u
<
z
v>
z
z
u.
O
Z
O
H
D
en
nt#
0ฃ
ft
5
5ft
Appendix B
B-3
-------
Coal R'emining BMP Guidance Manual
Table B.I is a compilation of baseline and post-mining median loading for acidity, iron,
manganese, aluminum, sulfate, and flow for each discharge, and a sum of the total change in
pollution load for each water quality parameter. From left to right, Table B.I shows monitoring
point ID (listed by permit number), permit baseline year (pre-mining data), review year (post-
mining data), baseline median load, post-mining median load, percent change in median, baseline
upper confidence interval, baseline lower confidence interval, post-mining upper confidence
interval, post-mining lower confidence interval, and "evaluation." The statistical summaries for
baseline ar|d post-mining loads typically include 12 monthly samples. The confidence intervals
give the range of values around the median in which the true population median occurs with a
1 !, , ilili'l '!' ' " " , ' ',;, i :!! . II i , " i v ,' i, ! ,1,1,iiป
95% probability. Thus, a comparison between baseline and post-mining confidence intervals
"Tv '':ฃ '' '' . u: ';'. ' :-i!|':t , r "' ' . .": ('<. .&',' ! j ' (I.r ' ! .'/ -S " ''''I > ! 'ป!'
indicates whether or not there has been a statistically significant change in water quality. The
,' 1'''1 ''f'lil , i!1' "' ' ' \' ! ', '" ' '' ' , I ", ' ' ' " :'!:' ,:'"' ซ"' '' i jj '' " '' ' ' :: , ' ' il "" , " ป'l'
four evaluation categories are no significant difference, significantly better, significantly worse
1 n',:!" i ,' : ',' . ' i ',.'''' ':. ', I I ', ' " -, . i i , ilf
and eliminated.
1 '' if!' . *v \: ' , ; '! ,.'.' | ' f , ,, ,. -,.' &
, ' Siil, .,"' : ' ,. , . ฃ' ? 'i I.., . ' : .. : :.;;;-:;*",
The eliminated category occurs where the post-mining upper confidence interval is zero
Ibs/day.
Significantly better occurs where the post-mining upper confidence limit is less than the
baseline lower confidence limit.
;! . . - - :':;, ' , ' :. ,1 ." ,.;, , s'4;ซ. fi'-:i : . :;* :i " - ;ii
Significantly worse occurs where the post-mining lower confidence limit is higher than
the baseline upper confidence limit.
No significant difference occurs where the confidence intervals overlap.
,hป ' llni 'InI
j :::
B-4
Appendix B
-------
Coal Reminins BMP Guidance Manual
Table B.I: Summary Statistics of Baseline and Post-Mining Loadings, by Parameter
1= Discharge Significantly Worsened
2= No Significant Difference in Discharge
3= Discharge Significantly Better
4= Discharge Eliminated
Permit ID
Allegheny-
1
Allegheny-2
Allegheny-3
Allegheny-4
Allegheny-5
Armstrong-
1
Armstrong-
2
Armstrong-
3
Armstrong-
4
Armstrong-
5
Armstrong-
7
Armstrong-
8
Armstrong-
9
Armstrong-
10
Armstrong-
11
Monitoring
Point ID
10
2
S-6
S-7
d-1p
BS12
MD1
MD2
MP-2
1A
D-1
D-112
D-4
W-1A
w-2A
w-3A
GK-13
GK-17
MP-2
MP14
MP15
MP17
MP21
MP22
MP23
MP24
c3-a
md-2
HU1
C-11
,S-20
HU1
Permit
Baseline
Year
1986
1986
1989
1989
1991
1991
1991
1991
1993
1984
1986
1986
1986
1986
1986
1986
1987
1987
1988
1988 .
1988
1988
1988
1988
1988
1988
1988
1988
1988
1989
1989
1990
Review
Year
1995
1995
1998
1989
1998
1995
1995
1995
1995
1990
1995
1995
1995
1992
1992
1992
1993
1988
1993
1997
1997
1997
1997
1997
1997
1997
1998
1998
1998
1995
1995
1997
Baseline
Median
Post-
Mining
Median
% Change
In Median
Baseline
Upper
Limit
Baseline
Lower
Limit
Post-
Mining
Upper
Limit
Aciditv
26.81
18.01
5.83
554.92
4.18
196.4
119.48
14.85
8.17
2.04
7.5
0.42
6.83
11.65
11.12
0.72
0.54
0
4.27
1.54
11.01
0.79
0.04
0.1
13.72
1.2
13.97
1.85
19.56
2.9
47.1
3.02
66.8
2.34
6.04
0
1.3
10.07
22.44
0
1.33
1.57
5.65
0.75
9.91
9.38
37.5
0.24
0.2
0.01
0
2.5
1.42
12.43
0.2
1.72
9.41
1.25
0
4.76
22.82
1.66
50.13
0
149.16%
-87.01%
3.60%
-100.00%
-68.90%
-94.87%
-81.22%
-100.00%
-83.72%
-23.04%
-24.67%
78.57%
45.10%
-19.48%
237.23%
-66.67%
-62.96%
N/A
-100.00%
62.34%
-87.10%
1473.42%
400.00%
1620.00%
-31.41%
4.17%
-100.00%
157.30%
16.67%
-42.76%
6.43%
-100.00%
34.87
21.25
12.43
844.09
5.04
209.51
139.22
26.68
15.64
3.28
17.71
1.05
11.34
15.64
16.24
1.57
0.75
0.01
6.28
2.72
18.7
5.46
0.15
0.75
21.27
2.02
24.98
3.63
28.78
3.44
54.02
6.69
18.71
14.76
-0.77
265.74
3.33
183.29
99.73
3.02
0.7
0.79
-2.71
-0.21
2.32
7.65
5.98
-0.14
0.31
0
2.26
0.36
3.32
-3.89
-0.06
-0.55
6.18
0.38
2.96
0.06
10.35
2.36
40.18
-0.65
105.34
2.92
8.54
0
1.96
22.36
37.96
0.19
2.52
3.5
9.21
1.2
20.45
12.72
57.3
0.28
0.46-
0.03
0
3.2
6.08
20.58
0.84
6.64
21.87
2.09
0
7.13
34.62
2.54
61.63
0
Post-
Mining
Lower
Limit
Evaluation
28.26
1.76
3.55
0
0.64
-2.22
6.93
-0.19
0.14
-0.37
2.09
0.3
-0.63
6.02
16.3
0.19
-0.07
0
0
1.8
-3.25
4.27
-0.45
-3.22
-3.07
0.41
0
2.39
11.01
0.77
38.63
0
2
3
2
4
3
3
3
3
2
2
2
2
2
2
1
2
2
2
4
2
2
2
2
2
2
2
4
2
2
2
2
4
Appendix B
B-5
-------
Coal Kemining BMP Guidance Manual
I !i r
i II
Permit ID
Armstrong-
12
Armstrong-
13
Armstrong-
14
Armstrong-
15
Armstrong-
16
Armstrong-
17
Armstrong-
18
Beaver-1
Butler-1
Butler-2
ButIer-3
Butler-4
Butler-5
Cambda-1
aarion-1
Clarion-2
Ctarion-3
C!arion-4
Monitoring
Point ID
mp2
mph
41
Unit 2
1
V2
HU1
HU1
D1
S-10
5W
2W
SAW
8W
S-116
S-13
S-200
S-91
S-95/96
DR2
1
MP9
MP13
SP-1
SP-28
SP-5
SP-6
1
RH-78
RH-79
RH-82
RH-84
RH-91
RH-93
RH-94
RH-96
1
2
Permit
Baseline
Year
1991
1991
1990
1990
1991
1992
1993
1994
1994
1988
1986
1984
1984
1984
86
86
86
86
86
1991
1991
1990
1990
1985
1985
1985
1985
1986
1990
1990
1990
1990
1990
1990
1990
1990
1990
1990
Review
Year
1995
1995
1995
1995
1993
1997
1998
1998
1998
1995
1991
1989
1989
1989
1994
1994
1994
1994
1994
1998
1998
1995
1995
1995
1995
1995
1995
1989
1994
1994
1994
1994
1994
1994
1994
1994
1996
1996
Baseline
Median
19.73
3.92
9.17
185.99
2.38
32.79
0.07
0.39
0.26
4.84
1.71
0.11
0.17
0.94
29.85
5.34
0.85
3.59
1.7
17.62
50.75
3.49
6.65
192.07
31.73
4.32
75
0.19
4.95
3.91
2.48
1.44
0.07
0.17
1.56,
4.81
0.47
0.84
Post-
Mining
Median
0.5
1.09
0
3.32
0
10.96
0
0.17
0
0.43
1.95
0
0.28
0.19
7.45
0
0
0
0
0
20.95
0.03
0
83.01
12.22
0
0
0.401
0
0
0.05
0.58
0
0.01
0
0
0
0.13
% Change
In Median
-97.47%
-72.19%
-100.00%
-98.21%
-100.00%
-66.58%
-100.00%
-56.41%
-100.00%
-91.12%
14.04%
-100.00%
64.71%
-79.79%
-75.04%
-100.00%
-100.00%
-100.00%
-100.00%
-98.58%
-58.72%
-99.14%
-100.00%
-56.78%
-61.49%
-100.00%
-100.00%
111.05%
-100.00%
-100.00%
-97.98%
-59.72%
-100.00%
-94.12%
-100.00%
-100.00%
-100.00%
-84.52%
Baseline
Upper
Limit
33.38
14.64
12.13
212.48
4.82
42.53
0.57
0.63
0.37
6.67
6.77
0.36
0.66
1.55
35.8
7.52
2.33
5.31
3.01
22.9
62.77
4.63
8.71
244.57
44.73
5.81
99.91
0.35
5.81
4.71
3.08
1.82
0.13
0.27
1.82
8.15
0.62
1.07
Baseline
Lower
Limit
6.09
-6.8
6.2
159.5
-0.07
23.05
-0.43
0.15
0.14
3.01
-3.35
-0.14
-0.32
0.33
23.9
3.16
-0.63
1.87
0.39
12.34
38.72
2.35
4.58
139.57
18.73
2.83
50.09
0.03
4.1
3.11
1.87
1.07
0.02
0.08
1.3
1.46
0.32
0.61
Post-
Mining
Upper
Limit
0.79
1.64
0.02
5.43
0
22.33
0
0.4
0.01
3.35
3.55
0
0.7
0.36
12.66
0
0
0
1.62
0
70.79
0.06
0
100.01
16.4
0.27
0
1.01
0
0
0.1
1.53
0.02
0.02
0
0
0
0.25
Post-
Mining
Lower
Limit
0.21
0.54
-0.02
1.2
0
-0.41
0
-0.05
-0.01
-2.49
0.35
0
-0.14
0.03
2.24
0
0
0
-1.62
0
-28.89
0
0
66.01
8.05
-0.27
0
-0.2
0
0
-0.01
-0.37
-0.02
0
0
0
0
0.02
Evaluation
3
2
3
3
4
3
4
2
3
2
2
4
2
2
3
4
4
4
2
4
2
3
4
3
3
3
4
2
4
4
3
2
2
3
4
4
4
3
B-6
Appendix B
-------
Coal Remining. BMP Guidance Manual
Perm it ID
Clarion-5
Clarion-6
Clearfield-1
Clearfield-2
Clearfield-3
Clearfield-4
Clearfield-5
Ciearfield-6
C1earfieid-7
Clearfield-8
Clearfield-9
Clearfield-
10
Clearfield-
11
CIinton-1
Clinton-2
Clinton-3
Fayette-1
Monitoring
Point ID
DR-1
1
2
3
unit 1
W10
W42
W43
W44
SF-1
SF10
SF4
SF6
SF61
tk-18
tk-21
TK-3
tk-37
tk-4
tk-7
SV-5
SV-8
R-3
R-5
R-8
12
13
TK4
TK7
1
2
HU1
HU2
HU3
subf-a
subf-b
subf-c
96
97
13
15A
SNW1A
GR-9
SEH-31
SHE-30
mp-4
mp-5
mp-6
mp-8
Permit
Baseline
Year
1990
1992
1992
1992
1985
1985
1985
1985
1985
1986
1986
1986
1986
1986
1985
1985
1985
1985
1985
1985
1988
1988
1988
1988
1988
1989
1989
1990
1990
1990
1990
1992
1992
1992
1993
1993
1993
1981
1981
1981
1981
1981
1988
1990
1990
1989
1989
1989
1989
Review
Year
1992
1998
1998
1998
1998
1998
1998
1998
1998
1998
1998
1998
1998
1998
1997
1997
1997
1997
1997
1997
1992
1992
1995
1995
1995
1997
1997
1996
1996
1994
1994
1998
1998
1998
1994
1994
1994
1995
1995
1995
1995
1996
1993
1993
1993
1993
1993
1993
1993
Baseline
Median
17.6
0.11
0.01
0.66
230.02
23.08
31.27
69.05
36.61
0.42
2.15
0.14
0.59
8.47
35.59
18.3
38.46
7.19
1.28
4.33
8.15
12.78
10.58
4.19
12.18
1.35
209.67
0.92
1.44
18.03
0.19
4.85
1.5
8.24
5.84
0.4
8.57
11.12
11.12
20.49
8.11
41.22
21.45
19.94
0.95
12.9
14.95
2.24
15.11
Post-
Mining
Median
39.67
0
0
0
71.33
23.6
47.17
125.32
47.08
0.11
0.03
0.06
0.49
1.06
42.44
1.65
29.6
5.33
0.41
0
12
11.56
0.065
1.4
0
0.97
173.81
0.4
0
0
0
4.34
0.75 .
3.17
6.5
0.13
2.85
0
0
0
0
32.27
2.59
6.21
5.1
4.88
0
0
1.17
% Change
In Median
125.40%
-100.00%
-100.00%
-100.00%
-68.99%
2.25%
50.85%
81.49%
28.60%
-73.81%
-98.60%
-57.14%
-16.95%
-87.49%
19.25%
-90.98%
-23.04%
-25.87%
-67.97%
-100.00%
47.24%
-9.55%
-99.39%
-66.59%
-100.00%
-28.15%
-17.10%
-56.52%
-100.00%
-100.00%
-100.00%
-10.52%
-50.00%
-61.53%
11.30%
-67.50%
-66.74%
-100.00%
-100.00%
-100.00%
-100.00%
-21.71%
-87.93%
-68.86%
436.84%
-62.17%
-100.00%
-100.00%
-92.26%
Baseline
Upper
Limit
29.46
0.22
0.06
1.22
289.12
38.1
48.42
111.18
61.14
0.59
3.69
0.25
9.14
14.84
48.81
29.08
42.63
11.29
1.77
5.47
10.56
19.68
15.01
6.47
19.48
2.28
269.13
1.24
2.1
29.12
0.75
8.22
1.99
10.62
8.95
0.67
10.88
18.63
18.63
31.44
13.64
61.34
44.59
25.79
1.85
16.95
20.33
4.79
19.63
Baseline
Lower
Limit
10.52
0
-0.04
0.09
170.92
8.04
14.11
26.91
12.06
0.24
0.59
0.02
-7.97
2.08
22.37
7.52
34.29
3.09
0.79
3.19
5.73
5.87
6.14
1.9
4.87
0.41
150.12
0.6
0.78
6.94
-0.87
1.48
1
5.86
2.74
0.14
6.26
3.6
3.6
9.53
2.58
21.06
-1.69
14.09
0.05
8.84
9.56
-0.32
10.58
Post-
Mining
Upper
Limit
73.23
0
0
0
107.81
50.89
73.56
215.63
70.36
0.18
0.07
0.13
0.98
6.53
51.62
6.35
38.05
6.67
0.52
0.01
15
15.02
0.4
2.09
0
1.68
203.94
0.54
0.01
0
0
6.86
1.15
4.39
8.53
0.35
5.09
0
0
0
0
51.09
24.17
-6.02
7.09
5.12
0
0
1.23
Post-
Mining
Lower
Limit
6.11
0
0
0
34.85
-3.69
20.78
35.02
23.8
0.03
0
-0.01
0.01
-4.42
33.26
-3.06
21.16
3.98
0.3
-0.01
10
8.1
-0.27
0.71
0
0.26
143.68
0.31
-0.01
0
0
1.82
0.35
1.95
4.46
0
0.61
0
0
0
0
13.5
-18.99
18.44
3.1
4.64
0
0
1.11
Evaluation
2
4
4
4
3
2
2
2
2
3
3
2
2
2
2
3
2
2
3
3
2
2
3
2
4
2
2
3
3
4
4
2
2
3
2
2
3
4
4
4
4
2
2
3
1
3
4
4
3
Appendix B
B-7
-------
11, , ',. "hi! ,:M; .!' -
Coal Remining BMP Guidance Manual
Permit ID
:ayette-2
Fayette-3
Fayette-4
Fayette-5
Fayette-6
;ayette-7
Fayette-8
Fayette-9
ayette-10
Fayette-11
:ayette-12
Fayette-13
Fayette-14
Fayette-15
Fayette-16
Greene-1
Greene-2
lndiana-1
lndlana-2
lndiana-3
ndiana-4
efferson-1
Jafferaon-2
Jefferson-3
Jefferson-4
Jefferson-5
Monitoring
Point ID
HU-1
MS100
MP6
mp-4
mp-hua
MP-1
MP48
MP49
MP-15
MP-28
mp-1
mp-1 1
mp-2
mp29
Mp68
D5
mp-1 9
mp-57
mp-60
mp56
MD1/MD2
MD8/BS29
MP-42
MP-8
MP-51
hut
H
J
K
L
M
N
O
MP-5
MP-15
HA)
2{B)
3(0)
4(D)
1
MP-51
MP-52
1
MP-1 3
HU-1
HU-1
MP-33
MP-8B
Permit
Baseline
Year
1984
1988
1988
1988
1988
1988
1989
1989
1988
1990
1989
1989
1989
1991
1991
1991
1991
1991
1991
1991
1991
1991
1994
1994
1987
1989
1988
1988
1988
1988
1988
1988
1988
1988
1988
1992
1992
1992
1992
1992
1992
1992
1984
1986
1989
1989
1989
1989
Review
Year
1992
1995
1993
1998
1998
1994
1996
1996
1994
1998
1992
1992
1992
1998
1997
1995
1998
1998
1998
1998
1995
1995
1996
1996
1988
1994
1995
1995
1995
1995
1995
1995
1995
1997
1997
1998
1998
1996
1998
1998
1998
1998
1993
1996
1992
1996
1998
1998
Baseline
Median
622.81
38.94
2.97
1408.74
1441
170.29
418.49
92.84
142.71
149.83
161.85
30.61
4.23
30.78
2.46
12.85
5.84
29.06
79.71
54.62
1.68
14.59
3.8
92.32
16.35
106.48
150.24
52.76
19.6
23.93
11.58
3.98
0
209.22
6.09
1.34
147.38
171.92
70.4
6.12
15.39
1.2
14.28
1.6
0.01
48.11
3.97
152.39
Post-
Mining
Median
167.96
0.3
3.09
932.4
1039
15.73
317.51
135.78
64.08
123.78
38.45
15.88
8.51
28.22
3.75
9.84
0
3.33
32.07
511.67
0.04
1.06
0.65
32.94
0
19.65
173.09
55.06
23.88
0.42
7.4
0.56
0
116.77
0.28
0
15.38
83.29
7.64
6.16
0
0.54
66.62
2.38
0
1.09
3.77
99.52
% Change
In Median
-73.03%
-99.23%
4.04%
-33.81%
-27.9%
-90.76%
-24.13%
46.25%
-55.10%
-17.39%
-76.24%
-48.12%
101.18%
-8.32%
52.44%
-23.42%
-100.00%
-88.54%
-59.77%
836.78%
-97.62%
-92.73%
-82.89%
-64.32%
-100.00%
-81.55%
15.21%
4.36%
21.84%
-98.24%
-36.10%
-85.93%
N/A
-44.19%
-95.40%
-100.00%
-89.56%
-51.55%
-89.15%
0.65%
-100.00%
-55.00%
366.53%
48.75%
-100.00%
-97.73%
-5.04
-34.69%
Baseline
Upper
Limit
919.04
54.78
6.72
1723
2218
252.6
546.47
134.95
170.13
247.01
204.87
43.13
5.87
71.31
4.91
17.64
12.46
58.11
130.24
175.15
5.61
36.39
22.71
132.84
22.77
186.91
225.69
90.82
24.89
31.92
25.25
10.29
0.01
348.3
9.93
2.62
180.55
213.48
87.85
7.18
19
6.24
29.91
2.14
0.09
56.81
6.6
187.55
Baseline
Lower
Limit
326.57
23.1
-0.79
1094
663
87.98
290.51
50.72
115.29
52.65
118.84
18.09
2.59
-9.75
0.01
8.05
-0.77
0
29.18
-65.91
-2.26
-7.21
-15.12
51.79
9.93.
26.06
74.77
14.69
14.3
15.93
-2.1
-2.34
0
70.12
2.23
0.07
114.2
130.36
52.95
5.07
11.78
-3.84
-1.35
1.06
-0.07
39.41
1.34
117.23
Post-
Mining
Upper
Limit
185.12
0.72
11.17
1063
1384
44.07
505.22
177.84
193.76
200.72
62.16
34.52
12.05
45.92
6.47
13.08
0
8.56
71
918.61
0.1
1.31
11.82
78.99
0
34.31"
222.89
113.87
38.6
12.56
16.13
1.01
0
200.3
0.56
0.01
23.62
234.27
16.45
8.85
0
0.86
154.42
4.87
0
4.25
5.43
162.98
Post-
Mining
Lower
Limit
150.79
-0.12
-4.98
801
694
-12.61
129.79
93.72
-65.6
46.85
14.74
-2.77
4.98
10.52
1.03
6.59
0
-1.89
-6.86
104.72
-0.03
0.8
-10.52
-13.11
0
4.99
123.29
-3.76
9.15
-11.73
-1.33
0.11
0
33.25
0
-0.01
7.13
-67.69
-1.17
3.47
0
0.22
-21.17
-0.11
0
-2.07
2.1
36.06
Evaluation
3
3
2
3
2
3
2
2
2
2
3
2
2
2
2
2
4
2
2
2
2
2
2
2
4
2
2
2
2
3
2
2
4
2
3
3
3
2
3
2
4
2
2
2
4
3
2
2
B-8
Appendix B
-------
Coal Reminins BMP Guidance Manual
Permit ID
Jefferson-6
Jefferson-7
Lawrence-1
SomerseM
Venango-1
Wash. -1
Wash. -2
Wash. -3
Wash. -4
Wash. -5
Wash. -7
West-
moreland-1
West-
moreland-2
West-
moreland-3
West-
moreland-4
West-
moreland-5
West-
moreland-3
West-
moreland-?
West-
moreIand-8
West-
moreland-9
Monitoring
Point ID
S-25
S-34
MP-1
1
SP16
1
HU1
A
CV103
CV4
MP-1
MP-2
d-1
sela
MP10
MP7
MP9
S8
CP2
Culvert
MD-1
MD-3
MD-4
MD-6
MD-7
HU-1
M
N
MP-3
MP-4
MP-4
MP-46
MP-47
MP-51
MP-52
MP-56
MP-60
MP-A
Permit
Baseline
Year
1993
1993
1991
1992
1989
1989
1986
1985
1985
1985
1989
1989
1987
1995
1984
1984
1984
1985
1986
1986
1986
1986
1986
1986
1986
1986
1985
1985
1986
1986
1987
1987
1987
1987
1987
1987
1987
1987
Review
Year
1998
1998
1995
1998
1998
1994
1993
1998
1998
1998
1998
1998
1996
1998
1993
1993
1993
1994
1990
1986
1990
1990
1990
1990
1990
1996
1993
1993
1991
1991
1998
1993
1993
1993
1993
1993
1993
1995
Baseline
Median
1.67
1.8
0.36
3.47
20.18
20.94
295.51
115.68
9411.66
1350.09
652.1 1
535.6
4.18
1.1
30.64
30.28
0.21
30.84
11.77-
3.58
3.74
5.94
16.99
167.25
125.77
570.84
8.21
2.13
9.76
284
12.15
590.44
469.53
8.1
2.96
6.34
6.36
5.95
Post-
Mining
Median
0.11
1.05
0
0
22.12
11.49
39.39
0.1
1324.6
118.4
6.03
0
0.79
0
27.71
45.08
0.69
7.78
4.52
0.22
5.41
0
9.68
0.97
28.78
401.91
7.02
0.57
0.92
365.04
0
525.86
663.91
18.78
2.26
6.06
2.69
1.4
% Change
In Median
-93.41%
-41.67%
-100.00%
-100.00%
9.61%
-45.13%
-86.67%
-99.91%
-85.93%
-91.23%
-99.08%
-100.00%
-81.10%
-100.00%
-9.56%
48.88%
228.57%
-74.77%
-61.60%
-93.85%
44.65%
-100.00%
-43.03%
-99.42%
-77.12%
-29.59%
-14.49%
-73.24%
-90.57%
28.54%
-100.00%
-10.94%
41.40%
131.85%
-23.65%
-4.42%
-57.70%
-76.47%
Baseline
Upper
Limit
2.86
2.93
0.52
4.98
26
39.36
388.62
160.2
11146.9
2
1585.7
1044.41
747.88
5.04
3.57
39.11
40.96
0.48
43.85
16.98
6.03
25.67
54.68
41.96
443.44
250.89
972.94
14.86
5.18
10.48
569.5
18.04
748.65
687.42
11.25
3.96
9.69
9.68
12.75
Baseline
Lower
Limit
0.48
1.1
0.19
1.96
14.36
11.14
202.78
71.16
7676.39
1114.47
259.8
322.24
3.33
-1.38
22.16
19.59
-0.05
17.83
6.55
1.12
-18.2
-42.8
-7.98
-108.96
0.63
168.74
1.55
0
9.03
-1.5
6.26
432.22
251.63
4.94
1.95
2.98
3.02
-0.87
Post-
Mining
Upper
Limit
0.18
2.89
0
0
24.09
21.25
57.28
0.17
2020.61
142.12
8.44
0
1.71
0
47.49
67.15
1.29
17.79
6.84
0.54
is.sa
0.12
13.7
0.98
50.23
602.25
9.76
2.64
1.49
608.76
0
762.95
1230.27
30.47
9.6
10.54
6.94
2.06
Post-
Mining
Lower
Limit
0.04
-0.89
0
0
20.14
1.72
21.49
0.03
628.6
94.67
3.61
0
-0.14
0
7.91
23
0.08
-2.23
2.19
-0.11
-8.05
-0.13
5.64
0.96
7.32
201.56
4.28
-1.52
0.36
121.33
0
288.77
97.53
7.08
-5.08
1.57
-1.58
0.75
Evaluation
3
2
4
4
2
2
3
3
3
3
3
4
3
4
2
2
2
3
2
3
2
2
2
2
2
2
2
2
3
2
4
2
2
2
2
2
2
2
Appendix B
B-9
-------
"',.; SB' ::.*i ' '. >. ,
Coal Remining BMP Guidance Manual
PormitID
West-
moreland-
10
West-
moreland-
11
West-
more!and-
12
West-
moreland-
13
West-
moreland-
14
West-
moreland-
15
West-
moreland-
16
West-
moreland-
17
West-
moreiand-
18
West-
moreland-
19
West-
moreland-
20
West-
moreland-
21
Monitoring
Point ID
MP12
MP3
MP-1
MP-2
MP-3
MP-4
MP-5
MP-6
MP-A
MP-B
MP-C
MP-D
mp-a
mp-b
HU-1
SLK-GW-
27
mp-8
SW18
1
2
3
MP16
MP5
MP6
mp-7
MP3
Permit
Baseline
Year
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1989
1989
1988
1994
1990
1989
1989
1989
1989
1993
1993
1993
1991
1992
Review
Year
1995
1992
1995
1995
1995
1995
1995
1995
1995
1995
1995
1995
1993
1993
1995
1999
1995
1993
1995
1995
1995
1999
1999
1999
1998
1997
Baseline
Median
37.68
1245.66
439.13
8.55
41.79
81.63
34.39
59.26
55.37
34.61
12.69
1.76
5.89
48.24
32.71
5.87
21.31
1.23
0.85
5.3
4.27
0.75
1.1
2.2
1.02
4.44
Post-
Mining
Median
0.76
842.7
0
7.76
30.24
0.37
83.86
106.05
42.1
18.24
20.34
0.5
3.17
18.1
10.66
0.9
18.58
0
0.67
5.1
7.17
0.49
0.02
1.74
0
0.88
% Change
In Median
-97.98%
-32.35%
-100.00%
-9.24%
-27.64%
-99.55%
143.85%
78.96%
-23.97%
-47.30%
60.28%
-71.59%
-46.18%
-62.48%
-67.41%
-84.67%
-12.81%
-100.00%
-21.18%
-3.77%
67.92%
-34.67%
-98.18%
-20.91%
-100.00%
-80.18%
Baseline
Upper
Limit
93.48
1413.04
594.61
14.41
72.07
129.46
73.68
88.79
92.66
51.68
28.11
2.82
7.44
58.58
38.39
6.99
26.52
1.4
0.99
7.71
6.49
0.95
1.58
2.82
1.71
6.05
Baseline
Lower
Limit
-18.13
1078.28
283.65
2.68
11.51
33.8
-4.91
29.73
16.08
17.54
-2.73
0.69
4.35
37.89
27.02
4.75 .
16.09
1.05
0.71
2.89
2.05
0.55
0.63
1.58
0.34
2.83
Post-
Mining
Upper
Limit
1.11
1042.3
0
14.77
36.04
3.54
131.99
222.74
67.76
26.01
28.62
1.18
7.38
31.2
15.82
1.56
28.22
0
0.99
11.45
15.75
0.65
0.09
2.79
0.07
1.69
Post-
Mining
Lower
Limit
0.41
643.1
0
0.75
24.44
-2.79
34.73
-10.64
16.43
10.48
12.06
-0.18
-1.06
5
5.49
0.25
8.97
0
0.35
-1.25
-1.41
0.32
-0.05
0.69
-0.07
0.06
Evaluation
2
3
4
2
2
3
2
2
2
2
2
2
2
3
3
3
2
4
2
2
2
2
3
2
3
3
B-10
Appendix B
-------
Coal Remining BMP Guidance Manual
| Permit ID
West-
moreland-
22
Monitoring
Point ID
103
69
mp-13
mp-16
Permit
Baseline
Year
1994
1994
1994
.1994
Review
Year
1998
1998
1998
1998
Baseline
Median
1.44
6.52
0.24
0.07
Post-
Mining
Median
0
0
0
0
% Change
In Median
-100.00%
-100.00%
-100.00%
-100.00%
Baseline
Upper
Limit
1.76
13.9
0.63
0.12
Baseline
Lower
Limit
1.13
-0.86
-0.16
0.01
Post-
Mining
Upper
Limit
0
0
0
0
Post-
Mining
Lower
Limit
0
0
0
0
Evaluatior
4
4
4
4
Aluminum
Allegheny-
1
Allegheny-3
Allegheny-4
Armstrong-
5
Armstrong-
7
Armstrong-
12
Armstrong-
13
Armstrong-
14
Armstrong-
15
Butler-3
Butler-4
Clarion-4
Clarion-5
Clearfield-4
Clearfield-7
10
2
d-1p
BS12
MD1
MD2
MP-2
MP14
MP15
MP17
MP22
MP23
MP24
mp2
mph
41
Unit 2
1
V2
S-116
S-13
S-200
S-91
S-95/96
DR2
2
DR-1
tk-18
tk-21
TK-3
tk-37
tk-4
tk-7
12
13
1986
1986
1991
1991
1991
1991
1988
1988
1988
1988
1988
1988
1988
1991
1991
1990
1990
1991
1992
86
86
86
86
86
1991
1990
1990
1985
1985
1985
1985
1985
1985
1989
1989
1995
1995
1998
1995
1995
1995
1993
1997
1997
1997
1997
1997
1997
1995
1995
1995
1995
1993
1997
1994
1994
1994
1994
1994
1998
1996
1992
1997
1997
1997
1997
1997
1997
1997
1997
2.86
1.46
0.59
22.01
11.78
0.09
0.3
0.18
0.56
0.1
0.01
1.04
0.1
0.43
0.43
1.23
20.53
0.2
2.2
3.55
0.59
0.12
0.44
0.26
0.39
0.02
1.96
4.65
3.34
2.77
0.34
0.06
0.39
0.08
10.45
6.15
0.16
0.12
4.07
6.17
0
0
0.25
0.11
1.42
0.1
0.5
0.11
0.1
0.2
0
0.21
0
0.78
0.37
0
0.1
0
0
0
0.01
3.56
2.2
0.22
0.91
0.63
0.01
0
0.08
9.21
115.03%
-89.04%
-79.66%
-81.51%
-47.62%
-100.00%
-100.00%
38.89%
-80.36%
1320.00%
900.00%
-51.92%
10.00%
-76.74%
-53.49%
-100.00%
-98.98%
-100.00%
-64.55%
-89.58%
-100.00%
-16.67%
-100.00%
-100.00%
-100%
-50.00%
81.63%
-52.69%
-93.41%
-67.15%
85.29%
-83.33%
-100.00%
0.00%
-11.87%
4.9
2.47
0.61
23.99
12.74
0.73
0.36
0.31
1.08
0.3
0.05
1.5
0.17
0.66
0.66
1.77
22.47
0.31
2.85
4.43
0.91
0.35
0.69
0.45
0.57
0.03
4.19
6.22
5.35
3.88
0.91
0.15
0.45
0.14
13.55
0.82
0.48
0.57
20.03
10.82
-0.55
0.23
0.05
0.04
-0.09
-0.03
0.08
0.03
0.2
0.2
0.7
18.6
0.1
1.55
2.67
0.26
-0.11
0.198
0.07
0.22
0.02
0.92
3.08
1.33
1.66
-0.23
-0.03
0.33
0.02
7.34
9.27
0.2
0.15
5.73
8.3
0.06
0
0.29
0.68
2.27
0.37
1.04
0.17
0.15
0.27
0
0.39"
0
1.34
2.95
0
0.62
0
0.09
0
0.02
6.19
2.76
0.69
1.1
0.83
0.02
0
0.13
11.19
3.01
0.11
0.08
2.4
4.05
-0.06
0
0.2
-0.47
0.55
-0.18
-0.05
0.04
0.06
0.13
0
0.09
0
0.22
-2.2
0
-0.43
0
-0.09
0
0
0.93
1.65
-0.26
0.72
0.43
0.01
0
0.03
7.24
2
3
3
3
3
2
4
2
2
1
2
2
2
3
2
4
3
4
3
2
4
2
4
2
4
2
2
3
3
3
2
2
4
2
2
Appendix B
B-ll
-------
i ilium ten?
111"!1 -v
Coat Remining BMP Guidance Manual
1 It!
111
!L
- -
Permit ID
Clearfield-
11
Fayette-1
Fayette-2
Fayette-4
:ayette-6
:ayette-7
Fayatte-8
Fayette-9
:ayette-10
Fayette-1 1
FayeHe-12
Fayette-1 4
Fayette-1 5
=ayette-16
efferson-3
efferson-4
efferson-5
efferson-6
efferson-7
Venango-1
Wash. -1
Wash. -2
Wash. -4
Wash. -5
Wash. -7
West-
rnoreland-1
West-
noreland-2
West-
Wast-
moreland-5
Monitoring
Point ID
subf-a
subf-b
subf-c
mp-4
mp-5
mp-6
mp-8
HU-1
MP6
MP-1
MP48
MP49
MP-1 5
MP-28
mp-11
mp-2
mp29
Mp68
mp-19
mp-57
mp-60
mp56
MD8/BS29
MP-42
MP-8
HU-1
HU-1
MP-33
MP-8B
S-25
S-34
MP-1
1
HU1
A
MP-1
MP-2
d-1
sela
MP10
MP7
MP9
S8
CP2
Culvert
HU-1
Permit
Baseline
Year
1993
1993
1993
1989
1989
1989
1989
1984
1988
1988
1989
1989
1988
1990
1989
1989
1991
1991
1991
1991
1991
1991
1991
1994
1994
1989
1989
1989
1989
1993
1993
1991
1989
1986
1985
1989
1989
1987
1995
1984
1984
1984
1985
1986
1986
1986
Review
Year
1994
1994
1994
1993
1993
1993
1993
1992
1993
1994
1996
1996
1994
1998
1992
1992
1998
1997
1998
1998
1998
1998
1995
1996
1996
1992
1996
1998
1998
1998
1998
1995
1994
1993
1998
1998
1998
1996
1998
1993
1993
1993
1994
1990
1986
1996
Baseline
Median
0.58
0.11
0.63
0.92
1.24
0.17
0.29
81.56
0.06
11.94
23.55
6.88
10.21
16.57
3.14
0.39
2.23
0.34
0.65
2.9
7.83
6.85
1.35
0.37
6.23
0
2.73
0.24
7.32
0.07
0.08
0.04
4.08
36.3
20.02
50.9
44.76
0.59
0.09
1.14
1.51
0.01
2.63
1.68
1.54
52.83
Post-
Mining
Median
0.61
0.03
0.24
0.52
0
0
0.02
22.39
0.27
1.04
28.69
12.82
6.13
6.9
1.27
0.97
2.24
0.43
0
0.16
3.5
53.42
0
0.07
2.22
0
0.02
0
4.59
0.01
0.11
0
1.45
2.45
0.04
0.18
0
0.1
0
2.96
3.88
0.07
0.78
0.63
0.13
26.86
% Change
In Median
5.17%
-72.73%
-61.90%
-43.48%
-100.00%
-100.00%
-93.10%
-72.55%
350.00%
-91.29%
21.83%
86.34%
-39.96%
-58.36%
-59.55%
148.72%
0.45%
26.47%
-100.00%
-94.48%
-55.30%
679.85%
-100.00%
-81.08%
-64.37%
N/A
-99.27%
-100.00%
-37.30%
-85.71%
37.50%
-100.00%
-64.46%
-93.25%
-99.80%
-99.65%
-100.00%
-83.05%
-100.00%
159.65%
156.95%
600.00%
-70.34%
-62.50%
-91.56%
-49.16%
Baseline
Upper
Limit
0.79
0.16
0.87
1.42
1.56
0.34
0.72
119.91
0.55
16.8
34.15
10.99
14.83
26.52
4.89
0.52
6.05
0.65
1.17
5.89
12.09
16.56
3.57
1.7
8.55
0.01
3.4
0.62
8.52
0.12
0.12
0.05
12.46
47.26
29.31
72.81
58.22
0.61
0.42
2.29
2.43
0.04
3.94
2.48
5.2
114.57
Baseline
Lower
Limit
0.37
0.06
0.38
0.41
0.92
-0.01
-0.16
43.2
-0.44
7.07
12.95
2.77
5.59
6.62
1.39
0.26
-1.59
0.03
0.14
-0.08
3.58
-2.85
-0.86
-0.97
3.91
0
2.06
-0.13
6.13
0.04
0.05
0.02
1.34
25.34
10.73
28.99
31.31
0.57
-0.23
-0.01
0.6
-0.03
1.31
0.87
-2.12
-8.91
Post-
Mining
Upper
Limit
0.79
0.06
0.42
0.54
0
0
0.02
28.44
0.95
3.23
43.05
16.3
23.1
12.9
3.18
1.33
2.97
0.75
0
0.4
6.7
91.33
0
0.69
4.32
0 -
0.04
0
6.44
0.01
0.26
0
2.37
4.03
0.09
0.3
0
0.33
0
4.7
5.62
0.12
1.47
0.88
0.25
46.87
Post-
Mining
Lower
Limit
0.42
0
0.05
0.5
0
0
0.02
16.33
-0.4
-1.15
14.33
9.34
-10.84
1.9
-0.64
0.6
1.51
0.1
0
-0.07
0.3
15.52
0
-0.55
0.13
0
-0.01
0
2.74
0.01
-0.04
0
0.53
0.86
0
0.06
0
-0.13
0
1.21
2.14
0.01
0.1
0.36
0
6.85
Evaluation
2
2
2
2
4
4
2
3
2
3
2
2
2
2
2
1
2
2
4
2
2
2
4
2
2
4
3
4
2
3
2
4
2
3
3
3
4
3
4
2
2
2
2
2
2
2
B-I2
Appendix B
-------
Coal Remining BMP Guidance Manual
Permit ID
West-
moreland-6
West-
moreland-7
West-
moreland-8
West-
more!and-9
West-
moreland-
10
West-
moreland-
12
West-
moreland-
13
West-
moreland-
14
West-
moreland-
15
West-
moreland-
16
West-
moreland-
18
West-
moreland-
19
Monitoring
Point ID
M
N
MP-3
MP-4
MP-4
MP-46
IVIP-47
MP-51
MP-52
MP-56
MP-60
MP-A
MP12
MP-1
MP-2
MP-3
MP-4
MP-5
MP-6
MP-A
MP-B
MP-C
MP-D
mp-a
mp-b
HU-1
SLK-GW-
27
mp-8
1
2
3
MP16
MP5
MP6
Permit
Baseline
Year
1985
1985
1986
1986
1987
1987
1987
1987
1987
1987
1987
1987
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1989
1989
1988
1994
1990
1989
1989
1989
1993
1993
1993
Review
Year
1993
1993
1991
1991
1998
1993
1993
1993
1993
1993
1993
1995
1995
1995
1995
1995
1995
1995
1995
1995
1995
1995
1995
1993
1993
1995
1999
1995
1995
1995
1995
1999
1999
1999
Baseline
Median
0.4
0.11
0.77
23.86
0.64
40.11
40.8
0.56
0.34
0.71
1.12
0.24
4.53
28.77
0.98
4.08
5.65
3.34
5.39
6.65
4.57
1.18
0.23
0.79
7.74
2.73
0.03
1.83
0.02
0.67
0.53
0.07
0.16
0.07
Post-
Mining
Median
0.54
0.07
0.01
38.29
0
39.55
53.41
1.88
0.29
0.77
0.6
0.03
5.73
0
0.87
3.37
0.03
6.88
8.22
4.95
2.13
1.98
0.07
0.72
0.23
0.08
0.02
0.74
0.02
0.64
0.89
0.03
0
0.26
% Change
In Median
35.00%
-36.36%
-98.70%
60.48%
-100.00%
-1.40%
30.91%
235.71%
-14.71%
8.45%
-46.43%
-87.50%
26.49%
-100.00%
-11.22%
-17.40%
-99.47%
105.99%
52.50%
-25.56%
-53.39%
67.80%
-69.57%
-8.86%
-97.03%
-97.07%
-33.33%
-59.56%
0.00%
-4.48%
67.92%
-57.14%
-100.00%
271 .43%
Baseline
Upper
Limit
0.73
0.33
1.04
47.88
0.9
50.39
58.68
0.8
0.45
1.03
1.58
0.79
10.49
40.45
1.7
6.39
8.74
6.18
7.69
10.84
6.77
2.47
0.35
0.97
9.64
3.33
0.04
2.23
0.02
1
0.84
0.09
0.21
0.09
Baseline
Lower
Limit
0.07
0
0.48
-0.18
0.38
29.84
22.92
0.3
0.22
0.37
0.65
-0.31
-1.45
17.09
0.26
1.77
2.56
0.49
3.09
2.46
2.37
-0.11
0.11
0.62
5.83
2.14
0
1.43
0.01
0.35
0.21
0.06
0.11
0.06
Post-
Mining
Upper
Limit
0.8
0.36
0.02
44.81
0
55.21
105.82
2.91
1.3
1.49
1.17
0.06
8.81
0
1.57
4.25
0.34
10.78
17.67
8.09 _
2.98
2.68
0.15
1.23
0.29
0.23
0.05
1.2
0.03
1.46
1.79
0.03
0
0.42
Post-
Mining
Lower
Limit
0.28
-0.24
0.01
31.76
0
23.88
1
0.84
-0.72
0.04
0.03
-0.01
2.65
0
0.17
2.48
-0.27
2.97
-1.24
1.8
1.29
1.29
-0.02
0.2
0.15
-0.07
0
0.29
0.01
-0.19
0
0.02
0
0.1
Evaluation
2
2
3
2
4
2
2
1
2
2
2
2
2
4
2
2
3
2
2
2
2
2
2
2
3
3
2
3
2
2
2
3
4
1
Appendix B
B-13
-------
Coal Remining BMP Guidance Manual
Permit ID
West-
moreland-
23
Monitoring
Point ID
103
69
Permit
Baseline
Year
1994
1994
Review
Year
1998
1998
Baseline
Median
0.12
0.69
Post-
Mining
Median
0
0
% Change
In Median
-100.00%
-100.00%
Baseline
Upper
Limit
0.17
1.41
Baseline
Lower
Limit
0.08
-0.04
Post-
Mining
Upper
Limit
0
0
Post-
Mining
Lower
Limit
0
0
Evaluation
4
4
Iron
Allegheny-!
AHegheny-2
Al!egheny-3
Allegheny-4
A!!egheny-5
Armstrong-
Armstrong-
Armstrong-
Armstrong-
Armstrong-
Armstrong-
Armstrong-
Armstrong-
Armstrong-
11
Armstrong-
Armstrong-
13
Armstrong-
14
10
2
S-6
S-7
d-1p
BS12
MD1
MD2
MP-2
1A
D-1
D-112
D-4
W-1A
w-2A
W-3A
MP-2
1
MP14
MP15
MP17
MP22
MP23
MP24
HU1
C-11
S-20
HU1
mp2
mph
41
48
Unit 2
1
1986
1986
1989
1989
1991
1991
1991
1991
1993
1984
1986
1986
1986
1986
1986
1986
1988
1988
1988
1988
1988
1988
1988
1988
1988
1989
1989
1990
1991
1991
1990
1990
1990
1991
1995
1995
1998
1989
1998
1995
1995
1995
1995
1990
1995
1995
1995
1992
1992
1992
1993
1995
1997
1997
1997
1997
1997
1997
1998
1995
1995
1997
1995
1995
1995
1995
1995
1993
0.1
0.09
0.37
24.63
0.06
4.7
1.81
0.02
0.03
0.39
1.55
0
0.05
0.27
0.78
0.14
0.02
0.41
0.01
0.75
0.03
0
0.16
0.01
0.13
0.51
9.21
0.04
1.97
0.02
0.02
0.24
23.76
0.21
0.11
0.12
3.5
1.55
0.03
0.88
1.37
0
0.01
0.34
0.01
0.02
0.06
0.16
5.36
0.23
0
0.02
0.01
0.29
0.29
0.03
0.09
0.01
0.03
0.24
7.09
0
0.27
0.01
0
0
0.42
0
10.00%
33.33%
845.95%
-93.71%
-50.00%
-81.28%
-24.31%
-100.00%
-66.67%
-12.82%
-99.35%
N/A
20.00%
-40.74%
587.18%
64.29%
-100.00%
-95.12%
0.00%
-61.33%
866.67%
N/A
-43.75%
0.00%
-76.92%
-52.94%
-23.02%
-100.00%
-86.29%
-50.00%
-100.00%
-100.00%
-98.23%
-100.00%
0.15
0.11
0.62
33.57
0.09
4.91
2.27
0.04
0.04
0.7
3.73
0.01
0.09
0.39
1.26
0.23
0.02
0.58
0.01
1.07
0.08
0.75
0.29
0.03
0.21
0.6
10.45
0.07
3.21
0.03
0.03
0.32
27.89
0.43
0.04
0.05
0.12
15.68
0.02
4.49
1.35
0
0.01
0.07
-0.64
0
0.01
0.13
0.3
0.03
0.01
0.25
0
0.43
-0.01
-0.55
0.02
-0.01
0.06
0.42
7.97
0
0.72
0
0.01
0.17
19.62
0
0.19
0.15
4.74
3.41
0.05
1.06
1.71
0
0.02
0.55
0.02
0.03
0.11
0.22
8.13
0.29
0
0.02
0.01
0.91
0.43
0.27
0.27
0.02
0.05
0.3
8.73
0
0.33
0.01
0
0
0.62
0
0.03
0.07
2.27
-0.42
0.01
0.7
1.04
0
0
0.13
0
0
0.01
0.1
2.59
0.1
0
0.01
0
-0.34
0.14
-0.21
-0.1
0
0.01
0.19
5.44
0
0.21
0
0
0
0.22
0
2
2
1
3
2
3
2
4
2
2
2
2
2
2
1
2
4
3
2
2
1
2
2
2
3
3
2
4
3
2
4
4
3
4
'ii'lr >
;,!
;;;B-14
pis, i , > ',1,*:! I,* i
IV , .'. j 1,1 9 II
Appendix B
'.'. :i
-------
Coal Remining BMP Guidance Manual
I^ermitlD
rmstrong-
5
Armstrong-
16
Beaver- 1
Butler-1
BuiIer-2
Butler-3
Butler-4
ButIer-5
Cambria- 'I
Clarion-1
Clarion-2
Clarion-3
Clarion-4
Clarion-5
Clearfield-1
Clearfield-2
Clearfield-3
Ciearfield-4
Monitoring
Point ID
V2
HU1
S-10
. 5W
2W
SAW
8W
S-116
S-13
S-200
S-91
DR-2
1
MP9
MP13
SP-1
SP-28
SP-5
SP-6
1
RH-78
RH-79
RH-82
RH-84
RH-91
RH-93
RH-94
RH-96
1
2
DR-1
unitl
W10
W42
W43
W44
SF-1
SF10
SF4
SF6
SF61
tk-18
tk-21
TK-3
tk-37
Permit
Baseline
Year
1992
1993
1988
1986
1984
1984
1984
1986
1986
1986
1986
1991
1991
1990
1990
1985
1985
1985
1985
1986
1990
1990
1990
1990
1990
1990
1990
1990
1990
1990
1990
1985
1985
1985
1985
1985
1986
1986
1986
1986
1986
1985
1985
1985
1985
Review
Year
1997
1998
1995
1991
1989
1989
1989
1994
1994
1994
1994
1998
1998
1995
1995
1995
1995
1995
1995
1989
1994
1994
1994
1994
1994
1994
1994
1994
1996
1996
1992
1998
1998
1998
1998
1998
1998
1998
1998
1998
1998
1997
1997
1997
1997
Baseline
Median
0.3
0.08
3.81
0.51
0.01
0.02
0.02
0.01
0.02
0.03
0
7.05
0.36
0.01
0.02
107.89
45.56
0.11
27.58
0.02
1.52
0.36
0.23
0.28
0.38
0.28
0.65
0.03
0.04
0.22
0.36
47.81
1.34
0.59
0.94
0.5
0.23
0.18
0.03
0.01
0.49
6.47
0.08
13.52
0.01
Post-
Mining
Median
0.13
0.34
2.99
0.22
0
0.01
0
0.01
0
0.01
0
0
0.17
0.02
0
24.34
15.51
0
0
1.125
0
0
0
0.25
0
0.07
0
0
0
0.08
2.63
18.73
0.61
0.27
0.91
0.41
0.06
0
0
0
0.05
9.87
0.03
8.71
0.01
% Change
In Median
-56.67%
325.00%
-21.52%
-56.86%
-100.00%
-50.00%
-100.00%
0.00%
-100.00%
-66.67%
N/A
-100%
-52.78%
100.00%
-100.00%
-77.44%
-65.96%
-100.00%
-100.00%
5525.00%
-100.00%
-100.00%
-100.00%
-10.71%
-100.00%
-75.00%
-100.00%
-100.00%
-100.00%
-63.64%
630.56%
-60.82%
-54.48%
-54.24%
-3.19%
-18.00%
-73.91%
-100.00%
-100.00%
-100.00%
-89.80%
52.55%
-62.50%
-35.58%
0.00%
Baseline
Upper
Limit
0.44
0.16
4.43
0.76
0.01
0.03
0.02
0.01
0.05
0.04
0.01
8.97
0.47
0.02
0.03
119.01
61.06
0.19
36.23
0.04
1-.76
0.46
0.27
0.35
0.46
0.32
0.74
0.06
0.06
0.27
0.53
59.45
1.82
0.74
1.45
0.85
0.29
0.29
0.05
0.02
0.94
8.85
0.14
14.68
0.01
Baseline
Lower
Limit
0.16
0
3.18
0.26
0.01
0.01
0.02
0.01
-0.02
0.02
-0.01
5.13
0.26
0
0
96.77
30.06
0.02
18.94
0
1.29
0.27
0.2
0.22
0.29
0.24
0.56
0.01
0.02
0.16
0.24
36.17
0.85
0.43
0.43
0.13
0.16
0.06
0
-0.01
0.03
4.09
0.02
12.36
0.01
Post-
Mining
Upper
Limit
0.3
0.5
3.99
0.36
0
0.02
0.01
0.02
0
0.05
0
0
0.42
0.03
0
30.16
19.19
0
0
1.54
0
0
0
0.48
0.11
0.17
0
0
0
0.11
5.85
23.58
0.95
0.35
1.49
0.54
0.12
0
0.01
0.01
0.22
10.22
0.06
11.32
0.01
Post-
Mining
Lower
Limit
-0.04
0.18
1.99
0.08
0
0
0
0
0
-0.03
0
0
-0.09
0.01
0
18.52
11.82
0
0
0.7
0 -
0
0
0.01
-0.11
-0.03
0
0
0
0.04
-0.6
13.88
0.28
0.18
0.34
0.29
0.01
0
-0.01
0
-0.12
9.51
0
6.1
0
Evaluation
2
1
2
2
4
2
3
2
4
2
4
4
2
2
4
3
3
4
4
1
4
4
4
2
3
3
4
4
4
3
2
3
2
3
2
2
3
4
2
2
2
1
2
3
2
Appendix B
B-15
-------
I I "I"
JUT.
Coal Remining BMP Guidance Manual
\ Permit ID
ClearfIeld-5
Clearffeld-6
Clearfield-7
Claarfield-8
Ctearfleld-9
Clearfteld-
10
Cloarfleld-
11
Clinton-1
Clinton-2
Cllnton-3
Fayette-1
Fayatte-2
Fayette-4
Fayette-5
Fayette-6
Fayette-7
Fayette-8
Fayette-9
Fayette-1 0
Fayette-1 1
Fayette-1 2
Fayette-1 3
Fayette-14
Monitoring
Point ID
tk-4
tk-7
SV-5
SV-8
R-3
R-5
R-8
12
13
TK4
TK7
1
2
HU1
HU2
HU3
subf-a
subf-b
subf-c
96
97
13
15A
SNW 1A
GR-9
SEH-31
SHE-30
mp-4
mp-5
mp-6
mp-8
HU-1
MP6
mp-4
mp-hua
MP-1
MP48
MP49
MP-1 5
MP-28
mp-1
mp-11
mp-2
mp29
Mp68
D5
mp-1 9
mp-57
mp-60
Permit
Baseline
Year
1985
1985
1988
1988
1988
1988
1988
1989
1989
1990
1990
1990
1990
1992
1992
1992
1993
1993
1993
1981
1981
1981
1981
1981
1988
1990
1990
1989
1989
1989
1989
1984
1988
1988
1988
1988
1989
1989
1988
1990
1989
1989
1989
1991
1991
1991
1991
1991
1991
Review
Year
1997
1997
1992
1992
1995
1995
1995
1997
1997
1996
1996
1994
1994
1998
1998
1998
1994
1994
1994
1995
1995
1995
1995
1996
1993
1993
1993
1993
1993
1993
1993
1992
1993
1998
1998
1994
1996
1996
1994
1998
1992
1992
1992
1998
1997
1995
1998
1998
1998
Baseline
Median
0.21
0.21
0.3
0.09
0.04
0.01
3.38
0.04
10.52
0.22
0.04
2.81
0.01
0.02
0.01
0.01
0.03
0.01
0.02
0.04
0.04
0.08
0.07
1.7
2.6
0.17
0.37
0.88
1.6
0.39
2.49
37.36
0.17
286
211
15.4
28.52
3.03
0.05
1.47
4.27
0.34
0.05
1.94
0.05
1.19
0.27
0.12
0.38
Post-
Mining
Median
0.16
0
0.36
0.1
0
0
2.06
0.01
6.75
0.12
0
0
0
0.01
0
0
0.02
0
0.01
0
0
0
0
1.23
0.37
0.07
1.11
0.22
0
0
0.09
11.59
0.11
68.69
55.27
0.6
23.44
5.87
0.05
0.77
1.25
0.2
0.16
1.72
0.06
1.71
0
0.01
0.17
% Change
In Median
-23.81%
-100.00%
20.00%
11.11%
-100.00%
-100.00%
-39.05%
-75.00%
-35.84%
-45.45%
-100.00%
-100.00%
-100.00%
-50.00%
-100.00%
-100.00%
-33.33%
-100.00%
-50.00%
-100.00%
-100.00%
-100.00%
-100.00%
-27.65%
-85.77%
-58.82%
200.00%
-75.00%
-100.00%
-100.00%
-96.39%
-68.98%
-35.29%
-75.98%
-73.81%
-96.10%
-17.81%
93.73%
0.00%
-47.62%
-70.73%
-41.18%
220.00%
-11.34%
20.00%
43.70%
-100.00%
-91.67%
-55.26%
Baseline
Upper
Limit
0.31
0.29
0.35
0.12
0.06
0
4.99
0.08
14.5
0.3
0.06
4.1
0.04
0.05
0.01
0.02
0.04
0.01
0.03
0.06
0.06
0.1
0.1
2.57
5.05
0.23
0.76
1.25
2.31
0.75
3.87
45.42
0.39
338
295
21.44
40.04
4.78
0.07
2.83
5.34
0.43
0.09
4.13
0.08
1.8
0.41
0.28
0.79
Baseline
Lower
Limit
0.11
0.13
0.23
0.05
0.02
0
1.75
0.01
6.54
0.15
0.01
1.52
0
-0.01
0.01
0.01
0.02
0
0.01
0.01
0.01
0.05
0.03
0.8
0.15
0.11
-0.02
0.51
0.87
0.03
1.11
29.29
-0.06
235
127
9.36
17
1.27
0.04
0.1
3.21
0.26
0.02
-0.25
0.02
0.58
0.13
-0.04
-0.02
Post-
Mining
Upper
Limit
0.24
0
0.43
0.13
0.01
0
3.44
0.02
7.83
0.2 .
0
0
0
0.02
0
0
0.03
0
0.01
0
0
0
0
1.7
4.02
0.09 '
1.31
0.23
0
0
0.1
13.08
0.49
80.46
72.69
1.37
38.42
7.92
0.15
1.31
1.95
0.34
0.27
3.78
0.08
2.33
0
0.03
0.29
Post-
Mining
Lower
Limit
0.09
0
0.33
0.07
-0.01
0
0.67
0
5.67
0.04
0
0
0
0
0
0
0.01
0
0
0
0
0
0
0.76
-3.28
0.05
0.91
0.2
0
0
0.09
10.08
-0.26
56.91
37.85
-0.16
8.47
3.81
-0.06
0.23
0.54
0.06
0.05
-0.35
0.04
1.09
0
-0.01
0.04
Evaluation
2
4
2
2
3
4
2
2
2
2
4
4
4
2
4
4
2
4
2
4
4
4
4
2
2
3
1
3
4
4
3
3
2
3
3
3
2
2
2
2
3
2
2
2
2
2
4
2
2
I ! .. i t!.
B-16
Appendix B
-------
Coal Remining BMP Guidance Manual
Permit ID
Fayette-15
Fayette-16
Greene-1
Greene-2
lndiana-1
lndiana-2
lndiana-3
Jefferson-1
Jefferson-2
Jefferson-4
Jefferson-5
Jefferson-6
Jefferson-7
Lawrence-1
Somerset-1
Somerset-2
Venango-1
Wash. -1
Wash. -2
Wash. -3
Wash. -4
Wash. -5
Wash. -6
West-
moreland-1
West-
moreland-2
Monitoring
Point ID
mp56
MD1/MD2
MD8/BS29
MP-42
MP-8
MP-51
hu1
H
J
K
L
M
N
0
MP5
MP15
KA)
2(B)
3(C)
1
MP-13
HU-1
MP-33
MP-8B
S-25
S-34
MP-1
1
SP16
1
1
HU1
A
CV103
CV4
MP-1
MP-2
d-1
D5
MP10
MP7
MP9
S8
Permit
Baseline
Year
1991
1991
1991
1994
1994
1987
1989
1988
1988
1988
1988
1988
1988
1988
1988
1988
1992
1992
1992
1984
1986
1989
1989
1989
1993
1993
1991
1992
1989
1993
1989
1986
1985
1985
1985
1989
1989
1987
1992
1984
1984
1984
1985
Review
Year
1998
1995
1995
1996
1996
1988
1994
1995
1995
1995
1995
1995
1995
1995
1997
1997
1998
1998
1996
1993
1996
1996
1998
1998
1998
1998
1995
1998
1998
1998
1994
1993
1998
1998
1998
1998
1998
1996
1997
1993
1993
1993
1994
Baseline
Median
1.11
0.03
0.23
0.05
1.79
0.05
4.01
6.96
1.84
0.62
1.35
0.11
0.05
0
13.63
0.18
0.01
6.66
4.76
0.23
0.02
0.71
0.17
8.55
0.01
0.01
0
0.25
0.04
0.09
0.25
29.24
1.93
38.7
17.36
8.49
6.38
0.06
4.08
0.1
0.76
0.03
0.1
Post-
Mining
Median
11.29
0.01
0.17
0
0.61
0
0.41
5.19
1.07
0.43
0.01
0.07
0.01
0
4.34
0.09
0
1.79
18.73
0.31
0.03
0.53
0
4.57
0.01
0.01
0
0
0.03
0.31
0.64
18.77
0.02
353.52
31.59
0.22
0
0.02
0.46
0.1
0.74
0.02
0.02
% Change
In Median
917.12%
-66.67%
-26.09%
-100.00%
-65.92%
-100.00%
-89.78%
-25.43%
-41.85%
-30.65%
-99.26%
-36.36%
-80.00%
N/A
-68.16%
-50.00%
-100.00%
-73.12%
293.49%
34.78%
50.00%
-25.35%
-100.00%
-46.55%
0.00%
0.00%
N/A
-100.00%
-25.00%
244.44%
156.00%
-35.81%
-98.96%
813.49%
81.97%
-97.41%
-100.00%
-66.67%
-88.73%
0.00%
-2.63%
-33.33%
-80.00%
Baseline
Upper
Limit
3.75
0.06
0.52
0.43
2.41
0.11
4.74
9.9
3.02
0.83
2.14
0.25
0.58
0.01
22.86
0.25
0.02
9.08
5.96
0.36
0.03
1.13
0.28
10.54
0.01
0.01
0.01
0.42
0.04
0.11
0.41
52.38
2.55
47.19
23.31
11.52
8.84
0.09
5.44
0.15
1.14
0.04
0.13
Baseline
Lower
Limit
-1.53
-0.01
-0.05
-0.34
1.17
-0.02
3.29
4.01
0.65
0.41
0.54
-0.04
-0.49
0
4.38
0.1
-0.01
4.25
3.55
0.1
-0.01
0.29
0.06
6.55
0
0
0
0.07
0.03
0.06
0.16
6.1
1.32
30.19
11.4
5.47
3.91
0.02
2.72
0.05
0.38
0.01
0.06
Post-
Mining
Upper
Limit
19.48
0.02
0.21
0.14
1.18
0
0.86
6.77
2.01
0.69
0.41
0.15
0.02
0
6.77
0.15
0
2.3
56.41
0.75
0.05
1.32
0
6.3
0.01
0.01
0
0
0.04
0.97
0.95
27.17
0.03
460.23
39.81
0.32
0
0.03
0.55
0.14
1.28
0.04
0.04
Post-
Mining
Lower
Limit
3.09
0
0.12
-0.14
0.04
0
-0.05
3.6
0.24
o.fs
-0.38
0
0
0
1.92
0.04
0
1.28
-18.95
-0.12
0.02
-0.25
0
2.84
0.01
0.01
0
0
0.02
-0.34
0.33
10.37
0.01
246.8
23.36
0.12
0
0.01
0.36
0.05
0.2
-0.01
-0.01
Evaluation
2
2
2
2
2
4
3
2
2
2
3
2
2
4
2
3
4
3
2
2
2
2
4
3
2 .
2
4
4
2
2
2
2
3
1
1
3
4
2
3
2
2
2
3
Appendix B
B-17
-------
,tM\Ym 1111111!! HIS
I!"- I1!11!"!1"!!:;" Sis!1'1"1!
'" Fill
p: "j:1!:1 R.I*;:;; i,
111!;'! I1', "
Coal Remining BMP Guidance Manual
Permit ID
West-
moreland-3
West-
moreIand-4
West-
moreland-5
West-
more!and-6
West-
moreIand-7
West-
moreland-8
West-
mcreland-9
West-
rrtoreland-
10
West-
moreland-
11
West-
moreland-
12
West-
moreland-
IS
West-
14
Monitoring
Point ID
CP2
Culvert
MD-1
MD-3
MD-4
MD-6
MD-7
HU-1
M
N
MP-3
MP-4
MP-4
MP-46
MP-47
MP-51
, .MfJ:gg
MP-56
MP-60
MP-A
MP12
MP3
MP-1
MP-2
MP-3
MP-4
MP-5
MP-6
MP-A
MP-B
MP-C
mp-a
mp-b
HU-1
MP-5A
Permit
Baseline
Year
1986
1986
1986
1986
1986
1986
1986
1986
1985
1985
1986
1986
1987
1987
1987
1987
1987
1987
1987
1987
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1989
1989
1988
1988
Review
Year
1990
1986
1990
1990
1990
1990
1990
1996
1993
1993
1991
1991
1998
1993
1993
1993
1993
1993
1993
1995
1995
1992
1995
1995
1995
1995
1995
1995
1995
1995
1995
1993
1993
1995
1995
Baseline
Median
0.03
0.15
0.08
0.17
0.75
7.3
3.8
46.62
0.08
0.02
0.57
7.1
1.04
53.49
32.67
0.04
0.01
0.01
0.04
3.21
0.27
94.65
71.8
0.2
4.03
16.32
3.67
7.11
0.92
0.42
0.5
0.03
0.25
2.48
0
Post-
Mining
Median
0.17
0.02
0.17
0
0.28
0.97
0.89
22.48
0.09
0
0.1
9.19
0
63.29
37.44
0.41
0.01
0
0.02
0.84
0.76
54.32
0
0.14
0.78
0.06
8.13
10.03
0.47
0.18
0.73
0.02
0.06
3.94
0.01
% Change
In Median
466.67%
-86.67%
112.50%
-100.00%
-62.67%
-86.71%
-76.58%
-51.78%
12.50%
-100.00%
-82.46%
29.44%
-100.00%
18.32%
14.60%
925.00%
0.00%
-100.00%
-50.00%
-73.83%
181.48%
-42.61%
-100.00%
-30.00%
-80.65%
-99.63%
121.53%
41.07%
-48.91%
-57.14%
46.00%
-33.33%
-76.00%
58.87%
N/A
Baseline
Upper
Limit
0.08
1.12
0.7
2
2.15
15.38
7.68
79.07
0.12
0.05
0.7
13.29
1.48
72.28
50.74
0.06
0.01
0.01
0.11
4.63
0.79
110.31
102.04
0.34
8.36
24.41
8.69
10.57
1.84
0.75
1.5
0.03
0.32
3.4
0.02
Baseline
Lower
Limit
-0.03
-0.84
-0.55
-1.67
-0.66
-0.8
-0.08
14.16
0.03
0
0.4
0.89
0.59
34.7
14.59
0.02
0
0
-0.04
1.79
-0.27
78.98
41.56
0.06
-0.3
8.23
-1.35
3.65
0
0.09
-0.5
0.02
0.18
1.56
-0.02
Post-
Mining
Upper
Limit
0.24
0.04
0.49
0
0.44
1.55
1.42
38.11
0.12
0
0.16
13.83
0
90.51
84.01
0.74
0.03
0
0.03
1.82
1.1 1_
62.26
0
0.28
1.06
0.34
13.57
22.16
0.76
0.28
1.19
0.04
0.09
5.31
0.03
Post-
Mining
Lower
Limit
0.09
0
-0.16
-0.01
0.11
0.39
0.35
6.85
0.05
0
0.04
4.56
0
36.05
-9.15
0.07
-0.01
0
0
-0.14
0.41
46.77
0
0
5
-0.23
2.69
-2.11
0.18
0.07
0.27
-0.01
0.01
2.56
-0.02
Evaluation
1
2
2
4
2
2
2
2
2
4
3
2
4
2
2
1
2
4
2
2
2
3
4
2
2
3
2
2
2
2
2
2
3
2
2
ft
B-18
Appendix B
i:,.1,
-------
Coal Remining BMP Guidance Manual
Permit ID
West-
moreland-
15
West-
moreland-
16
West-
moreland-
17
West-
moreland-
18
West-
moreland-
19
West-
moreland-
20
West-
moreland-
21
West-
moreland-
22
Monitoring
Point ID
SLK-GW-
27
mp-8
SW18
1
2
3
MP5
mp-7
MP3
mp-13
mp-16
Permit
Baseline
Year
1994
1990
1989
1989
1989
1989
1993
1991
1992
1994
1994
Manganese
Allegheny-1
Allegheny-3
Allegheny-4
Allegheny-5
Armstrong-
Armstrong-
Armstrong-
Armstrong-
Armstrong-
13
10
2
d-1p
BS12
MD1
MD2
MP-2
1A
1
C-11
S-20
mp2
mph
41
48
Unit 2
1986
1986
1991
1991
1991
1991
1993
1984
1988
1989
1989
1991
1991
1990
1990
1990
Review
Year
1999
1995
1993
1995
1995
1995
1999
1998
1997
1998
1998
1995
1995
1998
1995
1995
1995
1995
1990
1995
1995
1995
1995
1995
1995
1995
1995
Baseline
Median
0.37
0.67
0.04
0.06
0.08
0.05
0
0
0.04
0.02
0.03
Post-
Mining
Median
0
0.96
0
0.06
0.06
0.06
0
0
0
0
0
% Change
In Median
-100.00%
43.28%
-100.00%
0.00%
-25.00%
20.00%
N/A
N/A
-100.00%
-100.00%
-100.00%
0.25
0.56
0.15
1.14
0.74
0.07
0.13
0.51
1.09
0.07
0.5
0.23
0.09
0.37
0.12
6.35
0.88
0.12
0.07
0.24
0.52
0
0.02
0.33
0.25
0.01
0.22
0.05
0.06
0
0
0.31
252.00%
-78.57%
-53.33%
-78.95%
-29.73%
-100.00%
-84.62%
-35.29%
-77.06%
-85.71%
-56.00%
-78.26%
-33.33%
-100.00%
-100.00%
-95.12%
Baseline
Upper
Limit
0.69
0.87
0.05
0.08
0.11
0.08
0.01
0.01
0.06
0.11
0.05
0.3
0.79
0.17
1.32
0.79
0.12
0.21
0.75
1.39
0.09
0.68
0.38
0.14
0.46
0.14
7.12
Baseline
Lower
Limit
0.04
0.46
0.03
0
0.05
0.01
. 0
0
0.02
-0.07
0.01
Post-
Mining
Upper
Limit
0
1.38
0
0.09
0.12
0.16
0
0
0.01
0
0
Post-
Mining
Lower
Limit
0
0.55
0
0.03
0
0
0
0
0
0
0
0.18
0.32
0.14
0.96
0.69
0.02
0.05
0.26
0.8
0.05
0.31
0.07
0.05
0.28
0.1
5.58
1.28
0.18
0.1
0.31
0.65
0.01
0.03
0.53
0.29
0.01
0.3
0.06
0.09
0
0
0.44
0.47
0.05
0.03
0.16
0.39
-0.01
0.01
0.13
0.21
0
0.14
0.04
0.04
0
0
0.18
Evaluation
4
2
4
2
2
2
4
4
3
4
4
1
3
3
3
3
3
3
2
3
3
3
3
2
4
4
3
Appendix B
B-19
-------
1, F'
.Coal Remitting BMP Guidance Manual
"III i. ],;
III,:!"! '"1 , M
i'iivS, I 'I " ii. :'i
pi
HI
1'
m
!i!
il!iii,i
m
i!1:,.;
ft
I!"1
:::'
r "
;;;,
!
"
i
Permit ID
Armstrong-
14
Armstrong-
15
Beaver-1
ButJer-1
Butler-2
Butier-3
Bufer-4
Clarion-1
Clarion-2
CJarion-3
Clarfon-4
aadon-5
C!eari1e!d-2
C)earf1eId-3
Cfearfield-4
CtearfieW-5
Ctearfie!d-6
Monitoring
Point ID
1
V2
S-10
5W
2W
SAW
8W
S-116
S-13
S-200
S-91
S-95/96
DR2
SP-1
SP-28
SP-5
SP-6
1
RH-78
RH-79
RH-82
RH-84
RH-91
RH-93
RH-94
RH-96
1
2
DR-1
W10
W42
W43
W44
SF-1
SF10
SF4
SF6
SF61
tk-18
tk-21
TK-3
tk-37
tk-4
tk-7
SV-5
SV-8
R-3
R-5
Permit
Baseline
Year
1991
1992
1988
1986
1984
1984
1984
1986
1986
1986
1986
1986
1991
1985
1985
1985
1985
1986
1990
1990
1990
1990
1990
1990
1990
1990
1990
1990
1990
1985
1985
1985
1985
1986
1986
1986
1986
1986
1985
1985
1985
1985
1985
1985
1988
1988
1988
1988
Review
Year
1993
1997
1995
1991
1989
1989
1989
1994
1994
1994
1994
1994
1998
1995
1995
1995
1995
1989
1994
1994
1994
1994
1994
1994
1994
1994
1996
1996
1992
1998
1998
1998
1998
1998
1998
1998
1998
1998
1997
1997
1997
1997
1997
1997
1992
1992
1995
1995
Baseline
Median
0.91
0.35
1.93
0.8
0.01
0.03
0.04
3.6
0.44
0.15
0.24
0.24
0.12
5.78
3.94
0.13
1.22
0.05
0.84
0.38
0.55
0.38
0.48
0.25
0.19
0.61
0.04
0.95
0.33
3.99
7.26
0.94
9.54
0.05
0.05
0.02
0.04
0.11
6.2
1.7
6.9
2.11
0.31
0.4
0.38
0.98
0.47
0.42
Post-
Mining
Median
0
0.12
3.17
1.28
0
0.51
0.07
0.42
0
0.04
0
0
0
1.11
1.14
0
0
0.693
0
0
0
0.28
0
0.06
0
0
0
0.38
3.34
4.15
10.79
29.81
8.21
0.01
0
0.01
0.01
0.02
8.12
0.19
5.77
1.59
0.11
0
0.46
0.78
0.02
0.31
% Change
In Median
-100.00%
-65.71%
64.25%
60.00%
-100.00%
1600.00%
75.00%
-88.33%
-100.00%
-73.33%
-100.00%
-100.00%
-100.00%
-80.80%
-71.07%
-100.00%
-100.00%
1286.00%
-100.00%
-100.00%
-100.00%
-26.32%
-100.00%
-76.00%
-100.00%
-100.00%
-100.00%
-60.00%
912.12%
4.01%
48.62%
3071.28%
-13.94%
-80.00%
-100.00%
-50.00%
-75.00%
-81.82%
30.97%
-88.82%
-16.38%
-24.64%
-64.52%
-100.00%
21.05%
-20.41%
-95.74%
-26.19%
Baseline
Upper
Limit
1.51
0.45
2.39
1.65
0.02
0.07
0.06
4.22
0.58
0.34
0.36
0.36
0.14
6.27
4.57
0.17
1.55
0.1
0.97
0.44
0.66
0.46
0.52
0.3
0.22
0.94
0.05
1.09
0.47
6.16
11.04
1.45
14.61
0.06
0.08
0.03
0.66
0.19
8.01
2.53
7.75
3.54
0.46
0.49
0.43
1.51
0.64
0.62
Baseline
Lower
Limit
0.31
0.25
1.46
-0.05
0
0
0.02
2.98
0.28
-0.04
0.12
0.12
0.1
5.29
3.31
0.08
0.89
0
0.71
0.32
0.44
0.29
0.43
0.21
0.16
0.27
0.03
0.81
0.23
1.8
3.47
0.43
4.46
0.03
0.01
0
-0.59
0.02
4.39
0.87
6.05
0.68
0.16
0.31
0.32
0.45
0.28
0.21
Post-
Mining
Upper
Limit
0
0.24
4.02
1.8
0
0.76
0.1
0.95
0
0.22
0
0.06
0
1.54
1.46
0
0
1.07
0
0
0.01
0.53
0.19
0.16.
0
0
0
0.57
7
7.95
15.05
49.54
13.32
0.02
0
0.02
0.04
0.07
8.76
0.51
7.43
2.07
0.16
0
0.62
1.07
0.07
0.51
Post-
Mining
Lower
Limit
0
0
2.33
0.72
0
0.27
0.04
-0.1
0
-0.43
0
-0.06
0
0.68
0.82
0
0
0.31
0
0
0
0.04
-0.19
-0.04
0
0
0
0.18
-0.32
0.35
6.54
10.09
3.11
0
0
-0.01
-0.02
-0.03
7.49
-0.13
4.11
1.11
0.07
0
0.37
0.6
-0.03
0.11
Evaluation
4
3
2
2
4
1
2
3
4
2
4
3
4
3
3
4
4
1
4
4
3
2
3
3
4
4
4
3
2
2
2
1
2
3
4
2
2
2
2
3
2
2
2
4
2
2
3
2
!:,B-20
Appendix B
-------
Coal Reminins BMP Guidance Manual
PermitID
Clearfield-7
Clearfield-8
Clearfield-9
Clearfield-
10
Clinton-2
Clinton-3
Fayette-1
:ayette-2
Fayette-4
Fayette-6
Fayette-7
Fayette-8
Fayette-1 0
Fayette-1 1
Fayette-1 2
Fayette-1 3
Fayette-1 4
Fayette-1 5
Fayette-1 6
Greene-1
Greene-2
ndiana-3
efferson-1
Jefferson-2
efferson-4
Jefferson-5
Jefferson-6
Monitoring
Point ID
R-8
12
13
TK4
TK7
1
2
HU1
HU2
HU3
GR-9
SEH-31
SHE-30
mp-4
mp-5
mp-6
mp-8
HU-1
MP6
MP-1
MP48
MP49
MP-1 5
mp-1
mp-11
mp-2
mp29
Mp68
D5
mp-1 9
mp-57
mp-60
mp56
MD1/MD2
MD8/BS29
MP-42
MP-8
MP-51
hu1
HA)
2(B)
3(C)
1
MP-13
HU-1
MP-33
MP-8B
S-25
s-34
Permit
Baseline
Year
1988
1989
1989
1990
1990
1990
1990
1992
1992
1992
1988
1990
1990
1989
1989
1989
1989
1984
1988
1988
1989
1989
1988
1989
1989
1989
1991
1991
1991
1991
1991
1991
1991
1991
1991
1994
1994
1987
1989
1992
1992
1992
1984
1986
1989
1989
1989
1993
1993
Review
Year
1995
1997
1997
1996
1996
1994
1994
1998
1998
1998
1993
1993
1993
1993
1993
1993
1993
1992
1993
1994
1996
1996
1994
1992
1992
1992
1998
1997
1995
1998
1998
1998
1998
1995
1995
1996
1996
1988
1994
1998
1998
1996
1993
1996
1996
1998
1998
1998
1998
Baseline
Median
2.23
0.02
1.42
0.21
0.2
0.02
0
0.15
0.14
0.4
0.1
3.43
0.14
0.27
0.15
0.03
0.2
3.4
0.05
2.13
3.34
0.97
1.25
1.11
0.93
0.08
0.06
0.04
1.91
0.04
0.41
1.13
1.01
0.09
0.18
0.03
0.24
1.75
18.65
0.23
30.87
17.87
0.1
0.1
1.18
0.32
0.18
0.08
0.18
Post-
Mining
Median
1.48
0.07
2.2
0.11
0
0
0
0.21
0.01
0.18
0.34
1.9
1.29
0.15
0
0
0.05
2.82
0.08
0.84
2.88
1.26
0.7
0.62
0.43
0.16
0.67
0.05
1.79
0
0.32
1.06
5.64
0
0.43
0.01
0.13
0
3.31
0
6.04
15.8
3.87
6.36
0.64
0
0.14
2.05
0.15
% Change
In Median
-33.63%
250.00%
54.93%
-47.62%
-100.00%
-100.00%
N/A
40.00%
-92.86%
-55.00%
240.00%
-44.61%
821.43%
-44.44%
-100.00%
-100.00%
-75.00%
-17.06%
60.00%
-60.56%
-13.77%
29.90%
-44.00%
-44.14%
-53.76%
100.00%
1016.67%
25.00%
-6.28%
-100.00%
-21.95%
-6.19%
458.42%
-100.00%
138.89%
-66.67%
-45.83%
-100.00%
-82.25%
-100.00%
-80.43%
-11.58%
3770.00%
6260.00%
-45.76%
-100.00%
-22.22%
2462.50%
-16.67%
Baseline
Upper
Limit
2.77
0.03
1.84
0.3
0.27
0.05
0.01
0.3
0.2
0.56
0.2
4.45
0.27
0.43
0.2
0.05
0.3
4.48
0.09
2.75
4.37
1.34
1.52
1.35
1.22
0.1
0.2
0.07
2.68
0.08
0.8
1.64
2.14
0.2
0.47
0.08
0.33
3.3
26.91
0.44
37.76
20.29
0.21
0.13
1.49
0.51
0.22
0.11
0.29
Baseline
Lower
Limit
1.68
0
1.01
0.12
0.13
0.01
0
0.01
0.08
0.23
-0.02
2.41
0.01
0.1
0.1
0
0.08
2.3
0
1.5
2.32
0.59
0.98
0.87
0.64
0.05
-0.08
0.01
1.14
0.01
0.03
0.62
-0.13
-0.02
-0.12
-0.02
0.14
0.19
10.39
0.02
23.98
15.46
-0.01
0.07
0.87
0.14
0.14
0.06
0.11
Post-
Mining
Upper
Limit
1.87
0.12
2.56
0.16
0
0
0
0.34
0.01
0.26
-1.97
3.3
1.9
0.16
0
0
0.05
3.2
0.29
2.29
4.02
1.7
2.38
1.13
0.82
0.26-
1.04
0.1
2.3
0
0.77
1.65
9.37
0.01
0.54
0.05
0.19
0
3.9
0
7.07
24.83
8.19
11.22
0.88
0
0.21
3.38
0.45
Post-
Mining
Lower
Limit
1.09
0.02
1.84
0.06
0
0
0
0.07
0
0.1
2.65
0.5
0.67
0.14
0
0
0.05
2.43
-0.13
-0.61
1.74
0.83
-0.99
0.11
0.04
0.05
0.3
0.01
1.28
0
-0.14
0.48
1.91
-0.01
0.32
-0.02
0.06
0
2.72
0
5
6.77
-0.44
1.5
0.39
0
0.07
0.72
-0.15
Evaluation
2
2
2
2
4
4
4
2
3
2
1
2
1
2
4
4
3
2
2
2
2
2
2
2
2
2
1
2
2
4
2
2
2
2
2
2
2
4
3
4
3
2
2
1
2
4
2
1
2
Appendix B
B-21
-------
'"MB
Coal Retnining BMP Guidance Manual
i
Permit ID
Jefferson-7
Vanango-1
Wash. -2
Wash. -4
Wash. -5
Wash. -6
Wash. -7
Wost-
moretand-1
West-
moreland-2
West-
mor@!and-3
West-
rnore!and-7
West-
moreland-8
West-
more!and-9
West-
moreland-
10
West-
moreland-
12
West-
moreland-
13
West-
14
Monitoring
Point ID
MP-1
1
A
MP-1
MP-2
d-1
D5
sela
MP10
MP7
MP9
S8
CP2
Culvert
MP-3
MP-4
MP-4
MP-46
MP-47
MP-51
MP-52
MP-56
MP-60
MP-A
MP12
MP-1
MP-2
MP-3
MP-4
MP-5
MP-6
MP-A
MP-B
MP-C
MP-D
mp-a
mp-b
HU-1
MP-5A
Permit
Baseline
Year
1991
1989
1985
1989
1989
1987
1992
1995
1984
1984
1984
1985
1986
1986
1986
1986
1987
1987
1987
1987
1987
1987
1987
1987
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1989
1989
1988
1988
Review
Year
1995
1994
1998
1998
1998
1996
1997
1998
1993
1993
1993
1994
1990
1986
1991
1991
1998
1993
1993
1993
1993
1993
1993
1995
1995
1995
1995
1995
1995
1995
1995
1995
1995
1995
1995
1993
1993
1995
1995
Baseline
Median
0.3
0.71
3.58
9.49
6.59
0.15
1.53
0.11
1.05
0.63
0.02
1.32
0.05
0.05
0.34
6.9
0.07
9.78
8.03
0.24
0.14
0.33
0.31
0.98
1.88
4.58
0.19
0.7
1
0.62
1.01
1.42
0.88
0.17
0.15
0.07
0.59
0.77
0
Post-
Mining
Median
0
0.94
0.31
1.91
0
0.03
2.46
0
1.09
1.37
0.04
0.57
0.18
0.09
0.04
12.1
0
7.4
10.29
0.27
0.14
0.32
0.15
0.45
5.54
0
0.9
4.36
0.02
1.59
1.65
1.38
0.48
0.32
0.04
0.06
0.23
2.64
0.02
% Change
In Median
-100.00%
32.39%
-91.34%
-79.87%
-100.00%
-80.00%
60.78%
-100.00%
3.81%
117.46%
100.00%
-56.82%
260.00%
80.00%
-88.24%
75.36%
-100.00%
-24.34%
28.14%
12.50%
0.00%
-3.03%
-51.61%
-54.08%
194.68%
-100.00%
373.68%
522.86%
-98.00%
156.45%
63.37%
-2.82%
-45.45%
88.24%
-73.33%
-14.29%
-61.02%
242.86%
N/A
Baseline
Upper
Limit
0.4
1.05
5.09
18.63
8.37
0.17
2.17
0.27
1.35
0.86
0.04
1.76
0.05
0.09
0.44
13.63
0.09
12.05
11.74
0.33
0.18
0.55
0.43
1.28
4.4
6.56
0.29
1.08
1.56
1.23
1.45
2.21
1.32
0.42
0.24
0.09
0.69
0.91
0.02
Baseline
Lower
Limit
0.2
0.48
2.07
2.34
4.82
0.14
0.89
-0.04
0.74
0.4
0.01
0.87
0.04
0.01
0.22
0.16
0.03
7.5
4.3
0.13
0.09
0.1
0.18
0.67
-0.66
2.6
0.09
0.32
0.44
0
0.57
0.63
0.44
-0.08
0.06
0.06
0.48
0.64
-0.02
Post-
Mining
Upper
Limit
0
2.17
0.45
2.58
0
0.11
2.59
0
1.75
1.95
0.07
1.1
0.28
0.14
0.05
15.19
0
9.59
19.25
0.42
0.34.
0.59
0.26
0.63
7.29
0
1.66
6.26
0.14
2.48
3.34
2.17
0.65
0.41
0.07
0.1
0.29
3.64
0.03
Post-
Mining
Lower
Limit
0
-0.28
0.17
1.23
0
-0.05
2.34
0
0.42
0.78
-0.01
0.03
0.07
0.03
0.03
9.01
0
5.22
1.33
0.11
-0.07
0.04
0.04
0.27
3.79
0
0.14
2.47
-0.11
0.7
-0.03
0.6
0.31
0.23
0
0
0.15
1.64
0
Evaluation
4
2
3
2
4
3
1
4
2
2
2
2
1
2
3
2
4
2
2
2
2
2
2
3
2
4
2
1
3
2
2
2
2
2
2
2
3
1
2
B-22
Appendix B
-------
Coal Reminmg BMP Guidance Manual
Perm it ID
West-
moreland-
15
West-
moreland-
16
West-
moreland-
18
West-
moreland-
19
West-
moreland-
22
Monitoring
Point ID
SLK-GW-
27
mp-8
1
2
3
MP16
MP5
MP6
103
69
mp-13
mp-16
Permit
Baseline
Year
1994
1990
1989
1989
1989
1993
1993
1993
1994
1994
1994
1994
Review
Year
1999
1995
1995
1995
1995
1999
1999
1999
1998
1998
1998
1998
Baseline
Median
0.02
0.3
0.34
0.19
0.17
0.08
0.1
0.08
0.11
0.42
0.03
0.04
Post-
Mining
Median
0.01
3.3
0.36
0.09
0.11
0.03
0
0.11
0
0
0
0
% Change
In Median
-50.00%
1000.00%
5.88%
-52.63%
-35.29%
-62.50%
-100.00%
37.50%
-100.00%
-100.00%
-100.00%
-100.00%
Baseline
Upper
Limit
0.03
0.37
0.39
0.26
0.24
0.09
0.14
0.09
0.14
0.75
0.24
0.06
Baseline
Lower
Limit
0
0.24
0.3
0.12
0.11
0.06
0.07
0.06
0.08
0.09
-0.18
0.01
Post-
Mining
Upper
Limit
0.03
5.12
0.44
0.27
0.28
0.04
0
0.18
0
0
0
0
Post-
Mining
Lower
Limit
0
1.47
0.28
-0.09
0
0.02
0
0.03
0
0
0
0
Evaluatior
2
1
2
2
2
3
4
2
4
4
4
4
Sulfate
Allegheny-1
Allegheny-2
AIIegheny-3
Allegheny-4
Allegheny-5
Armstrong-
Armstrong-
Armstrong-
Armstrong-
Armstrong-
Armstrong-
Armstrong-
10
2
S-6
S-7 '
d-1p
BS12
MD1
MD2
MP-2
1A
D-1
D-112
D-4
w-1A
w-2A
W-3A
GK-13
GK-17
MP-2
1
MP14
MP15
MP17
MP21
MP22
MP23
MP24
1986
1986
1989
1989
1991
1991
1991
1991
1993
1984
1986
1986
1986
1986
1986
1986
1987
1987
1988
1988
1988
1988
1988
1988
1988
1988
1988
1995
1995
1998
1989
1998
1995
1995
1995
1995
1990
1995
1995
1995
1992
1992
1992
1993
1988
1993
1995
1997
1997
1997
1997
1997
1997
1997
16.35
72.12
22.72
1244.61
19.4
343.77
202.67
70.92
16.93
41.83
2.42
3.26
43.27
28.48
13.63
3.7
8.33
0.03
48.95
137.56
0.46
10.08
1.1
0.07
0.11
0.45
1.06
44.62
10.59
307.44
266.69
7.93
88.47
88.88
0
16.31
34.29
69.01
20.56
30.44
80.23
59.2
105.18
2.58
0
3.41
20.75
3.74
46.41
25.92
0.32
2.53
16.95
1.11
172.91%
-85.32%
1253.17%
-78.57%
-59.12%
-74.26%
-56.15%
-100.00%
-3.66%
-18.03%
2751.65%
530.67%
-29.65%
181.71%
334.34%
2742.70%
-69.03%
-100.00%
-93.03%
-84.92%
713.04%
360.42%
2256.36%
357.14%
2200.00%
3666.67%
4.72%
52.47
122.38
34.39
1521.2
27.14
804.78
261 .68
114.68
34.81
67.92
13.02
4.63
69.89
35.42
18.41
4.8
12.01
0.17
70.64
177.66
0.67
16.47
1.28
0.12
0.16
4.76
2.86
-19.78
21.86
11.04
968.02
11.66
-117.24
143.66
27.16
-0.95
15.74
-8.18
1.9
16.66
21.54
8.85
2.6
4.65
-0.11
27.26
97.45
0.24
3.69
0.91
0.02
0.06
-3.86
-0.74
160.3
15.02
418.26
305.96
11.89
182.02
150.33
4.16'
20.65
55.96
136.72
67.13
56.41
120.57
102.51
126.41
5.38
0
8.17
35.76
4.63
65.85
43.87
0.93
5.52
25.22
1.65
-71.05
6.16
196.63
227.43
3.97
-5.08
27.42 .
-4.16
11.97
12.62
1.31
-26
4.48
39.9
15.88
83.94
-0.21
0
-1.35
5.76
2.84
26.97
7.97
-0.29
-0.46
8.68
0.58
2
3
1
3
2
2
2
3
2
2
2
2
2
1
2
1
2
4
3
3
1
1
1
2
2
1
2
Appendix B
B-23
-------
Cgg/ Risinining BMP Guidance Manual
ParmitID
Armstrong-
8
Armstrong-
9
Armstrong-
10
Armstrong-
11
Armstrong-
12
Armstrong-
13
Armstrong-
14
Armstrong-
16
Armstrong-
17
Armstrong-
18
Baaver-1
BuUer-1
Butler-2
8ut!er-3
Buiier-4
Butler-5
Cambria-1
Clarion-1
Clarion-2
Clarion-3
Clarion-4
Clarfon-5
Cfarion-6
Claarfleld-1
Clearfleld-2
Monitoring
Point ID
c3-a
md-2
HU1
C-11
S-20
HU1
mp2
mph
41
48
Unit 2
1
HU1
HU1
D1
S-10
5W
2W
SAW
8W
S-116
S-13
S-200
S-91
S-95/96
DR2
1
MP9
Mp13
SP-1
SP-28
SP-5
SP-6
1
RH-78
1
2
DR-1
1
2
3
unitl
W10
Permit
Baseline
Year
1988
1988
1988
1989
1989
1990
1991
1991
1990
1990
1990
1991
1993
1994
1994
1988
1986
1984
1984
1984
86
86
86
86
86
1991
1991
1990
1990
1985
1985
1985
1985
1986
1990
1990
1990
1990
1992
1992
1992
1985
1985
Review
Year
1998
1998
1998
1995
1995
1997
1995
1995
1995
1995
1995
1993
1998
1998
1998
1995
1991
1989
1989
1989
1994
1994
1994
1994
1994
1998
1998
1995
1995
1995
1995
1995
1995
1989
1994
1996
1996
1992
1998
1998
1998
1998
1998
Baseline
Median
21.04
4.62
195.5
3.98
56.82
1.17
45.44
4.96
17.8
9.33
312.42
27.75
2.35
0.51
1.7
174.39
162.27
1.88
4.49
11.36
117.45
29.13
9
7.47
12.56
32.65
162.91
18.08
35.65
540.9
219.97
8.16
74.84
2.77
0.54
0
31.35
19.88
1.15
1.95
8.8
318.53
63.04
Post-
Mining
Median
59.9
97.77
239.86
5.22
90.44
0
6.63
6.55
0
0
4.94
0
7.14
0.54
0
23.48
281.84
0
116.99
40.41
37
0
37.12
0
5.26
0
264.13
0
0
111.79
142.8
0
0
0
0
0
40.06
306.33
0
0
0
113.2
22.66
% Change
In Median
184.70%
2016.23%
22.69%
31.16%
59.17%
-100.00%
-85.41%
32.06%
-100.00%
-100.00%
-98.42%
-100.00%
203.83%
5.88%
-100.00%
-86.54%
73.69%
-100.00%
2505.57%
255.72%
-68.50%
-100.00%
312.44%
-100.00%
-58.12%
-100.00%
62.13%
-100.00%
-100.00%
-79.33%
-35.08%
-100.00%
-100.00%
-100.00%
-100.00%
N/A
27.78%
1440.90%
-100.00%
-100.00%
-100.00%
-64.46%
-64.05%
Baseline
Upper
Limit
60.05
10.15
322.4
4.8
68.1
2.69
83.26
9.08
21.79
12.51
345.91
35.42
3.9
0.95
2.62
211.44
233.31
2.33
5.96
18.9
144.07
34.81
18.55
9.82
17.7
37.19
200.48
25.98
50.56
633.8
276.11
12.28
134.82
4.87
0.92
2.27
48.78
34.02
2.27
3.03
12.73
387.19
114.45
Baseline
Lower
Limit
-17.98
-0.92
68.61
3.15
45.55
-0.36
7.63
0.84
13.81
6.14
278.92
20.08
0.8
0.07
0.77
137.35
91.23
1.42
3.02
3.82
90.82
23.45
-0.55
5.12
7.42
28.11
125.35
10.17
20.74
448
163.82
4.03
14.85
0.68
0.15
-2.27
13.92
5.75
0.04
0.86
4.87
249.87
11.63
Post-
Mining
Upper
Limit
84.17
137.71
324.3
10.36
112.59
0
7.93
8.45
0.01
0.05
7.17
0
9.26
0.89
0
34.01
427.5
0
169.27
63.6
66.27
0
84.46
0
11.51
0
367.06
0
0
172.58
190.45
0.3
0
0.31
0
0
46.12
427.54
0
0
0
173.83
31.77
Post-
Mining
Lower
Limit
35.62
57.83
155.42
-0.12
68.28
0
5.33
4.64
-0.01
-0.05
2.7
0
5.02
0.19
0
12.94
136.19
0
64.7
17.21
7.73
0
-10.21
0
-1
0
161.21
0
0
51
95.14
-0.3
0
-0.31
0
0
34
185.13
0
0
0
52.56
13.56
Evaluation
2
1
2
2
1
4
2
2
3
3
3
4
1
2
4
3
2
4 .
1
2
3
4
2
4
2
4
2
4
4
3
2
3
4
3
4
4
2
1
4
4
4
3
2
B-24
Appendix B
-------
Coal Reminine BMP Guidance Manual
Perm it ID
ClearfieId-3
Clearfield-4
Clearfield-5
Clearfield-6
Clearfield-7
Clearfield-8
Clearfielcl-9
Clearfield-1
Clearfield-1
Clinton-1
Clinton-2
Clinton-3
Fayette-1
Fayette-2
Fayette-3
Fayette-4
Fayette-5
Fayette-6
Favette-7
Monitoring
Point ID
W42
W43
W44
SF-1
SF10
SF4
SF6
SF61
TK-3
tk-18
tk-21
tk-37
tk-4
tk-7
SV-5
SV-8
R-3
R-5
R-8
12
13
TK4
TK7
1
2
HU 1
HU2
HU3
subf-a
subf-b
subf-c
13
15A
96
97
SNW1A
GR-9
SEH-31
SHE-30
mp-4
mp-5
mp-6
mp-8
HU-1
MS100
MP6
mp-4
mp-hua
MP-1
MP48
Permit
Baseline
Year
1985
1985
1985
1986
1986
1986
1986
1986
1985
1985
1985
1985
1985
1985
1988
1988
1988
1988
1988
1989
1989
1990
1990
1990
1990
1992
1992
1992
1993
1993
1993
1981
1981
1981
1981
1981
1988
1990
1990
1989
1989
1989
1989
1984
1988
1988
1988
1988
1988
1989
Review
Year
1998
1998
1998
1998
1998
1998
1998
1998
1997
1997
1997
1997
1997
1997
1992
1992
1995
1995
1995
1997
1997
1996
1996
1994
1994
1998
1998
1998
1994
1994
1994
1995
1995
1995
1995
1996
1993
1993
1993
1993
1993
1993
1993
1992
1995
1993
1998
1998
1994
1996
Baseline
Median
143.29
293.17
95.95
3.11
0
4.11
0.31
16.74
179.92
125.04
58.65
90.44
7.93
18.15
13.9
29.68
19.28
15.84
143.19
1.93
290.52
8.83
11.51
26.83
0.33
21.08
4.4
27.93
14.09
8.22
26.61
60.58
6.61
8.65
9.59
344.25
45.73
68.76
14.52
34.26
30.65
5.47
36.78
955.89
158.66
6.73
2297.02
1119.78
151.45
735.46
Post-
Mining
Median
51.1
208.7
56.08
0.98
0.09
0.64
44.64
5.79
159.05
240.43
6.49
30.31
1.52
0
19.82
35.54
0.53
8.43
136.72
3.85
310.11
1.6
0
0
0
19.4
4.64
16.65
17.12
2.72
8.31
0
0
0
0
225.93
20.26
52.82
32.98
10.4
0
0
1.14
448.05
0.35
3.22
708.19
539.57
223.12
1286.57
% Change
In Median
-64.34%
-28.81%
-41.55%
-68.49%
N/A
-84.43%
14300.00%
-65.41%
-11.60%
92.28%
-88.93%
-66.49%
-80.83%
-100.00%
42.59%
19.74%
-97.25%
-46.78%
-4.52%
99.48%
6.74%
-81.88%
-100.00%
-100.00%
-100.00%
-7.97%
5.45%
-40.39%
21.50%
-66.91%
-68.77%
-100.00%
-100.00%
-100.00%
-100.00%
-34.37%
-55.70%
-23.18%
127.13%
-69.64%
-100.00%
-100.00%
-96.90%
-53.13%
-99.78% .
-52.15%
-69.17%
-51.81%
47.32%
74.93%
Baseline
Upper
Limit
226.07
484.05
194.56
3.86
1.23
5.94
5.53
26.47
206.99
174.87
86.47
113.97
10.8
21.79
15.88
43.09
26.03
20.95
163.3
3.35
380.4
11.63
20.58
47.73
1.34
27.11
6.23
35.69
20.65
11.76
32.29
108.73
18.51
17.39
20.74
502.02
72.46
115.31
23.92
41.9
35.98
10.99
40.65
1207.33
190.73
12.23
3795.72
1531.05
224.93
1143.47
Baseline
Lower
Limit
60.52
102.29
-2.66
2.36
-1.23
2.28
-4.91
7.01
152.86
75.2
30.83
66.91
5.05
14.51
11.91
16.26
12.53
10.73
123.07
0.5
200.64
6.04
2.45
5.94
-0.67
15.04
2.57
20.18
7.53
4.68
20.93
12.43
-5.29
-0.08
-1.55
186.49
19.01
22.22
5.12
26.61
25.32
-0.05
32.91
704.45
126.59
1.23
798.32
708.51
77.98
328.44
Post-
Mining
Upper
Limit
74.32
288.67
79.96
1.78
0.14
1.87
67.84
23.25
203.61
305.94
25.78
45.8
2.13
0
27.06
69.97
4.51
14.08
179.82
6.71
393.72
2.42
0
0
0
29.44
5.82
24.77
21.97
5.72
15.04
0
0
0
0
255.83
102.41
81.62
47.26
10.69
0
0
1.15
530.84
2.31
5.53
959.29
820.34
850.22
1605.91
Post-
Mining
Lower
Limit
27.87
127.46
32.2
0.18
0.04
-0.58
21.43
-11.67
114.49
174.92
-12.81
14.82
0.92
0
12.58
1.11
-3.46
2.78
93.61
1
226.51
0.79
0
0
0
9.37
3.46
8.52
12.27
-0.29
1.58
0
0
0
0
196.03
-61.89
24.02
18.69
10.11
0
0
1.12
365.25
-1.61
0.91
457.08
258.8
-403.98
967.24
Evaluation
2
2
2
3
2
3
1
2
2
1
3
3
3
4
2
2
3
2
2
2
2
3
4
4
4
2
2
2
2
2
3
4
4
4
4
2
2
2
2
3
4
4
3
3
3
2
2
2
2
2
Appendix B
B-25
-------
Coat Remitting BMP Guidance Manual
iliiijlllll!-! liillHI!,
"IW: , ..-I,
Permit ID
Fayette-8
Fayetta-9
Fayette-10
Fayette-11
Fayetle-12
Fayette-13
Fayette-14
Fayetta-15
Fayette-16
Qreene-1
Green e-2
lrxiiana-1
lndiana-2
lndiana-3
lndiana-4
Jefferson-2
Jefferson-3
Jefferson-5
Jefferson-6
Jafferson-7
Lawrence-1
Somerset-1
Sornerset-2
Venango-1
Washing-
ton-1
Monitoring
Point ID
MP49
MP-15
MP-28
mp-1
mp-11
mp-2
mp29
Mp68
D5
mp-1 9
mp-57
mp-60
mp56
MD1/MD2
MD8/BS29
MP-42
MP-8
MP-51
hu1
H
J
K
L
M
N
O
MP15
MP5
KA)
2(B)
3(C)
4(D)
1
MP51
MP52
MP-1 3
HU-1
HU-2
MP-33
MP-8B
S-25
S-34
MP-1
1
SP16
1
1
HU1
Permit
Baseline
Year
1989
1988
1990
1989
1989
1989
1991
1991
1991
1991
1991
1991
1991
1991
1991
1994
1994
1987
1989
1988
1988
1988
1988
1988
1988
1988
1988
1988
1992
1992
1992
1992
1992
1992
1992
1986
1989
1989
1989
1989
1993
1993
1991
1992
1989
1993
1989
1986
Review
Year
1996
1994
1998
1992
1992
1992
1998
1997
1995
1998
1998
1998
1998
1995
1995
1996
1996
1988
1994
1995
1995
1995
1995
1995
1995
1995
1997
1997
1998
1998
1996
1998
1998
1998
1998
1996
1992
1992
1998
1998
1998
1998
1995
1998
1998
1998
1994
1993
Baseline
Median
108.52
217.8
245.8
285.84
84.96
14.41
33.76
10.39
30.29
0
12.93
44.43
61.09
9.73
8.46
8.39
280.52
1.86
1454.81
256.37
152
42.49
57.1
23.31
6.28
0
32.32
280.64
0
1359.89
901.6
279.41
34.96
30.82
19.63
7.32
1.37
11.41
207
160.44
2.2
11.3
11.88
10.94
0.91
96.17
53.53
593.85
Post-
Mining
Median
286.36
367.84
473.19
55.97
18.15
15.07
65.81
4.76
42.96
0
26.87
58.07
382.1
0
11.81
2.81
307.8
0
101.56
335.11
150.81
65.77
2.34
63.05
1.47
0
6.64
415.5
0
182.71
840.32
63.79
30.09
0
8.13
117.06
0
1.57
42.74
138.56
44.92
0
0.95
0
7.48
141.8
46.16
2519.02
% Change
In Median
163.88%
68.89%
92.51%
-80.42%
-78.64%
4.58%
94.93%
-54.19%
41.83%
N/A
107.81%
30.70%
525.47%
-100.00%
39.60%
-66.51%
9.72%
-100.00%
-93.02%
30.71%
-0.78%
54.79%
-95.90%
170.48%
-76.59%
N/A
-79.46%
48.05%
N/A
-86.56%
-6.80%
-77.17%
-13.93%
-100.00%
-58.58%
1499.18%
-100.00%
-86.24%
-79.35%
-13.64%
1941.82%
-100.00%
-92.00%
-100.00%
721.98%
47.45%
-13.77%
324.18%
Baseline
Upper
Limit
165.54
322.73
400.45
330.13
116.43
18.96
87.9
18.34
44.7
2.65
25.11
94
132.49
42.8
16.88
13.97
383.92
1.86
2238.44
345.93
218.05
48.17
78.35
38.3
11.89
0.08
41.22
501.73
6.71
2016.81
1388
432.03
40.73
38.16
32.18
10.16
3.36
48.26
226.98
206.68
5.78
17.07
15.31
14.02
1.47
132.01
70.53
759.01
Baseline
Lower
Limit
51.5
112.88
91.16
241.56
53.49
9.87
-20.38
2.44
15.88
-2.65
0.76
-5.14
-10.32
-23.34
0.05
2.81
177.11
1.86
671.19
166.81
85.94
36.17
35.86
8.32
0.66
-0.08
23.42
59.56
-6.71
702.97
415.2
126.78
29.19
23.48
7.09
4.48
-0.61
-25.43
187.02
114.2
-1.37
5.53
8.46
7.85
0.34
60.33
36.53
428.69
Post-
Mining
Upper
Limit
413.41
693.39
640.08
89.13
49.56
22.1
88.03
7.88
49.26
0
58.1
132.99
886
0
14.16
8.57
366.2
0
171.51
441.72
309.17
99.71
30.89
120.47
2.56
0
8.17
694.68
0.79
299.61
1019.61
87.33
39.26
0
10.67
263.62
0
2.35
87.47
210.39
87.85
7.84
3.4
0
15.11
165.67
133.65
3237.63
Post-
Mining
Lower
Limit
159.31
42.29
306.3
22.8
-13.25
8.05
43.6
1.64
36.67
0
-4.37
-16.86
-121.8
0
9.46
-2.95
249.4
0
31.61
228.5
-7.55
31.83
-26.22
5.67
0.37
0
5.11
136.33
-0.79
65.82
661.02
40.26
20.92
0
5.59
-29.5
0
0.78
-1.98
66.73
1.99
-7.84
-1.5
0
-0.15
117.93
-41.34
1800.42
Evaluation
2
2
2
3
3
2
2
2
2
4
2
2
2
4
2
2
2
4
3
2
2
2
3
2
2
4
3
2
2
3
2
3
2
4
2
2
4
2
3
2
2
2
3
4
2
2
2
1
B-26
Appendix B
-------
Coal Remining BMP Guidance Manual
Permit ID
Washing-
ton-2
Washing-
ton-3
Washing-
ton-4
Washing-
ton-5
Washing-
ton-6
Washing-
ton-?
Iwestmore-
land-1
IWestmore-
lland-1
IWestmore-
!and-2
jWestmore-
lland-3
jWestmore-
land-4
Westmore-
land-5
Westmore-
land-6
Westmore-
land-?
Westmore-
Iand-8
Westmore-
land-9
Westmore-
land-10
Westmore-
land-11
Westmore-
land-12
Monitoring
Point ID
A
CV103
CV4
MP-1
MP-2
d-1
D5
sela
MP10
MP7
MP9
S8
CP2
Culvert
MD-1
MD-3
MD-4
MD-6
MD-7
HU-1
M
N
MP-3
MP-4
MP-4
MP-46
MP-47
MP-51
MP-52
MP-56
MP-60
MP-A
MP12
MP3
MP-1
MP-2
MP-3
Permit
Baseline
Year
1985
1985
1985
1989
1989
1987
1992
1995
1984
1984
1984
1985
1986
1986
1986
1986
1986
1986
1986
1986
1985
1985
1986
1986
1987
1987
1987
1987
1987
1987
1987
1987
1988
1988
1988
1988
1988
Review
Year
1998
1998
1998
1998
1998
1996
1997
1998
1993
1993
1993
1994
1990
1986
1990
1990
1990
1990
1990
1996
1993
1993
1991
1991
1998
1993
1993
1993
1993
1993
1993
1995
1995
1992
1995
1995
1995
Baseline
Median
167.85
8369.96
1107.28
1891.27
2602.83
14.86
584.17
2.49
101.17
47.7
0
192.77
12.62
5.86
76.03
15.84
32.78
493.48
328.92
1117.86
62.34
5.96
24.53
482.45
4.65
917.57
972.18
18.78
8.02
36.3
48.43
89.82
96.47
3386.86
78.61
7.73
36.09
Post-
Mining
Median
84.59
3305.5
1189.98
297.08
0
10.31
601
0
77.16
181.95
7.97
85.18
8.54
6.49
41.83
0
21.46
0
59.5
641.62
121.18
2.96
2.34
1238.06
0
688.07
2728.85
5.77
19.59
49.58
24.66
20.15
128.95
3201.9
0
68.42
126.28
% Change
In Median
-49.60%
-60.51%
7.47%
-84.29%
-100.00%
-30.62%
2.88%
-100.00%
-23.73%
281.45%
N/A
-55.81%
-32.33%
10.75%
-44.98%
-100.00%
-34.53%
-100.00%
-81.91%
-42.60%
94.39%
-50.34%
-90.46%
156.62%
-100.00%
-25.01%
180.69%
-69.28%
144.26%
36.58%
-49.08%
-77.57%
33.67%
-5.46%
-100.00%
785.12%
249.90%
Baseline
Upper
Limit
198.99
9446.53
1680.24
2361.95
2998.6
24.26
707.38
4.23
187.84
125.51
0.82
265.22
18.84
6.32
333.63
122.67
65.64
935.48
563.98
1601.29
157.63
14.6
33.54
728.08
8.17
1135.08
1342.1
21.13
10.34
50.69
58.37
111.52
214.68
4387.86
210.22
10.57
56.99
Baseline
Lower
Limit
136.71
7293.39
534.32
1420.6
2207.1
5.46
460.96
0.76
14.5
-30.1
-0.82
120.31
6.4
5.4
-181.58
-90.99
-0.08
51.48
93.85
634.43
-32.95
-2.67
15.53
236.82
1.14
700.05
602.25
16.44
5.7
21.92
38.49
68.12
-21.74
2385.85
-53
4.89
15.19
Post-
Mining
Upper
Limit
125.67
3305.5
1357.27
424.19
0
13.71
762.56
0
102.55
233.17
12.26
187.77
11.66
9.94
59.17
0
30.87
0
93.37
900.54
143.16
11.07
3.76
1718.41
0
808.37
3508.84
10.28
31.64
105.57
44.69
25.7
157.23
3961.25
0
107.27
162.88
Post-
Mining
Lower
Limit
43.52
3305.5
1022.69
169.97
0
6.92 ,
439.44
0
51.77
130.73
3.68
-17.41
5.42
3.04
24.49
0
12.04
0
25.63
382.7
99.2
-5.15
0.93
757.71
0
567.76
1948.87
1.27
7.55
-6.41
4.63
14.61
100.67
2442.54
0
29.58
89.68
Evaluatior
3
3
2
3
4
2
2
4
2
1
1
2
2
2
2
4
2
4
3
2
2
2
3
1
4
2
1
3
2
2
2
3
2
2
4
1
1
Appendix B
B-27
-------
Coal Reminins BMP Guidance Manual
!!!
it [,
V"
is
!,;
i?
"',
ii>
!",
1,
ki
P!
I
III
1
Si
Permit ID
Westmore-
land-13
Westmore-
and-14
Westmore-
and-15
Westmore-
and-16
Westmore-
and-17
Westmore-
and-18
Westmore-
and-19
Westmore-
and-20
Westmore-
and-21
Westmore-
and-22
Monitoring
Point ID
MP-4
MP-5
MP-6
MP-A
MP-B
MP-C
MP-D
mp-a
mp-b
HU-1
MP-5A
SLK-GW-2
7
mp-8
SW18
1
2
3
MP16
MP5
MP6
mp-7
MP3
103
69
mp-13
mp-16
Permit
Baseline
Year
1988
1988
1988
1988
1988
1988
1988
1989
1989
1988
1988
1994
1990
1989
1989
1989
1989
1993
1993
1993
1991
1992
1994
1994
1994
1994
Review
Year
1995
1995
1995
1995
1995
1995
1995
1993
1993
1995
1995
1999
1995
1993
1995
1995
1995
1999
1999
1999
1998
1997
1998
1998
1998
1998
Baseline
Median
77.27
15.63
60.51
0.06
0
1.83
0
14.9
105.94
145.68
21.31
15.89
25.18
3.89
8.78
10.96
20.59
5.81
5.74
7.04
4.09
0.3
14.86
77.99
6.63
3.88
Post-
Mining
Median
17.73
90.44
130.71
19.42
19.7
18.49
0.7
10.06
7.77
142.81
2.74
2.45
62.75
0
4.9
19.28
8.14
3.82
0.44
0
14.03
4.7
0
0
0
0
% Change
In Median
-77.05%
478.63%
116.01%
32266.67%
N/A
910.38%
N/A
-32.48%
-92.67%
-1.97%
-87.14%
-84.58%
149.21%
-100.00%
-44.19%
75.91%
-60.47%
-34.25%
-92.33%
-100.00%
243.03%
1466.67%
-100.00%
-100.00%
-100.00%
-100.00%
Baseline
Upper
Limit
137.74
67.65
102.61
22.35
9.53
5.56
0.31
18.78
135.65
189.91
27.82
19.66
33.46
4.28
12.99
14.7
39.32
6.52
7.38
11.33
5.52
0.46
20.61
110.87
33.83
7.13
Baseline
Lower
Limit
16.8
-36.39
18.4
-22.23
-9.53
-1.9
-0.31
11.03
76.24
101.44
14.81
12.12
16.89
3.51
4.57
7.23
1.87
5.1
4.09
2.75
2.65
0.14
9.1
45.11
-20.57
0.64
Post-
Mining
Upper
Limit
29.58
127.46
173.81
43.08
35.23
31.35
1.41
25.39
24.56
171.31.
4.44
4.26
79.47
0
6.7
34.18
12.98
5.35
1.55
2.65
24
6.77
0
0.39
0
0
Post-
Mining
Lower
Limit
5.89
53.42
87.6
-4.23
4.17
5.64
-0.01
-5.27
-9.03
114.3
1.03
0.63
46.02
0
3.1
4.38
3.3
2.29
-0.67
-2.65
4.06
2.63
0
-0.39
0
0
Evaluation
2
2
2
2
2
1
2
2
3
2
3
3
1
4
2
2
2
2
3
3
2
1
4
3
4
4
Flow
Allegheny-1)
AIJegheny-2
WIegbeny-3
Mlogheny-4
Wogheny-5
Armstrong-
rmstrong-
rmstrong-
10
2
S-6
S-7
d-1p
BS12
MD1
MD2
MP-2
1A
D-1
D-112
D-4
W-1A
W-2A
W-3A
1986
1986
1989
1989
1991
1991
1991
1991
1993
1984
1986
1986
1986
1986
1986
1986
1995
1995
1998
1989
1998
1995
1995
1995
1995
1990
1995
1995
1995
1992
1992
1992
8
10
2.4
136
2.4
52.98
28.65
11
2.5
66
18
2
25
18.06
15.33
6.72
4.5
0.5
29.7
29
1.2
15
14
0
2.2
50.13
22.38
14.98
20.47
13.05
8
10
-43.75%
-95.00%
1137.50%
-78.68%
-50.00%
-71.69%
-51.13%
-100.00%
-12.00%
-24.05%
24.33%
649.00%
-18.12%
-27.74%
-47.81%
48.81%
15.74
16.33
3.77
158.12
2.56
94.38
33.24
20.51
4.67
93.93
32.04
2.93
38.84
21.75
21.07
8.98
0.26
3.67
1.03
113.88
2.24
11.58
24.06
1.49
0.33
38.07
3.96
1.07
11.16
14.37
9.59
4.46
13.04
0.67
41.26
34.38
1.6
30.31
23.77
0.87
2.58
78.47
45.23
52.54
42.88
17.61
14.35
12.54
-4.04
0.33
18.14
23.62
0.8
-0.31
4.23
-0.87
1.82
21.78
-0.47
-22.58
-1.94
9.39
1.65
7.46
2
3
1
3
3
2
3
3
2
2
2
2
2
2
2
2
:""B-;28
Appendix B
-------
Coal Remining BMP Guidance Manual
Permit ID
Armstrong-
4
Armstrong-
5
Armstrong-
6
Armstrong-
7
Armstrong-
8
Armstrong-
9
Armstrong-
10
Armstrong-
11
Armstrong-
12
Armstrong-
13
Armstrong-
14
Armstrong-
15
Armstrong-
16
Armstrong-
17
Armstrong-
18
Beaver-1
Butler-1
Butler-2
Butler-3
Butler-4
ButIer-5
Monitoring
Point ID
QK-13
GK-17
MP-2
1
MP14
MP15
MP17
MP21
MP22
MP23
MP24
c3-a
md-2
HU1
C-11
S-20
HU1
mp2
mph
41
48
Unit 2
1
V2
HU1
HU1
D1
S-10
5W
2W
SAW
8W
S-116
S-13
S-200
S-91
S-95/96
DR2
1
Permit
Baseline
Year
1987
1987
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1989
1989
1990
1991
1991
1990
1990
1990
1991
1992
1993
1994
1994
1988
1986
1984
1984
1984
86
86
86
86
86
1991
1991
Review
Year
1993
1988
1993
1995
1997
1997
1997
1997
1997
1997
1997
1998
1998
1998
1995
1995
1997
1995
1995
1995
1995
1995
1993
1997
1998
1998
1998
1995
1991
1989
1989
1989
1994
1994
1994
1994
1994
1998
1998
Baseline
Median
1.98
0.02
8.1
10
0.1
2.6
0.1
0.1
0.1
0.25
1
7
2.7
27.73
0.6
7.1
0.5
6.4
0.9
2.18
2.48
13
4.5
31.5
4.1
0.3
1.33
29.7
70
2
7.5
11
14.06
14.1
1.91
0.99
1.46
1.59
86
Post-
Mining
Median
0.75
0
0.58
1
1.63
13.5
3.25
0.63
3.15
20
1.2
15.1
27.1
12.03
0.5
6.7
0
0.95
2
0
0
0.74
0
0.85
1.35
0.25
0
6.6
73
0
13.8
2.7
3.7
0
11.05
0
0.55
0
52.4
% Change
In Median
-62.12%
-100.00%
-92.84%
-90.00%
1530.00%
419.23%
3150.00%
530.00%
3050.00%
7900.00%
20.00%
115.71%
903.70%
-56.62%
-16.67%
-5.63%
-100.00%
-85.16%
122.22%
-100.00%
-100.00%
-94.31%
-100.00%
-97.30%
-67.07%
-16.67%
-100.00%
-77.78%
4.29%
-100.00%
84.00%
-75.45%
-73.68%
-100.00%
478.53%
-100.00%
-62.33%
-100.00%
-39.07%
Baseline
Upper
Limit
2.93
0.11
11.83
15.89
0.18
4.51
0.15
0.13
0.13
7.02
1.88
23.21
5.49
43.19
0.77
8.61
1.15
9.73
1.54
2.41
3.15
15.04
6.11
40.3
9.36
0.58
2.13
34.94
110.16
2.42
10.98
14.9
18.35
16.23
4.32
1.2
2.14
1.98
108.1
Baseline
Lower
Limit
1.03
-0.08
4.37
4.11
0.02
0.69
0.05
0.07
0.07
-6.52
0.12
-9.21
-0.09
12.26
0.43
5.59
-0.15
3.07
0.26
1.94
1.81
10.96
2.89
22.7
-1.16
0.02
0.52
24.46
29.83
1.58
4.02
7.1
9.77
11.97
-0.5
0.78
0.77
1.2
63.9
Post-
Mining
Upper
Limit
1.29
0
1.56
1.95
1.93
20.78
5.78
1.97
7.11
33.67
2.26
19.83
36.45
17.92
0.7
9.72
0
1.25
2.81
0.01
0.01 -
1.04
0
1.39
1.76
0.54
0
10.96
107.36
0
20.47
4.9
8.23
0
21.99
0
1.66
0
91.03
Post-
Mining
Lower
Limit
0.21
0
-0.41
0.05
1.32
6.22
0.72
-0.72
-0.81
6.33
0.14
10.37
17.75
6.14
0.3
3.68
0
0.65
1.19
-0.01
-0.01
0.44
0
0.31
0.94
-0.04
0
2.24
38.64
0
7.13
0.5
-0.83
0
0.11
0
-0.56
0
13.77
Evaluation
2
4
3
3
1
1
1
2
2
2
2
2
1
2
2
2
4
3
2
3
3
3
4
3
2
2
4
3
2
4
2
3
3
4
2
4
2
4
2
Appendix B
B-29
-------
Coal Remitting BMP Guidance Manual
Permit ID
Cambria-1
Clarion-1
Clariort-2
CIarlon-3
Ctarion-4
Clarion-5
Clarion-6
Ctearflald-1
Clearfield-2
Clearfleld-3
CIearfield-4
Clearfield-5
Clearfie!d-6
Clearfield-7
Clearfleld-8
Clearfield-9
Cloarfield-1
g
Clearfleld-1
Clinton-1
Monitoring
Point ID
MP9
Mp13
SP-1
SP-28
SP-5
SP-6
1
RH-78
1
2
DR-1
1
2
3
unitl
W10
W42
W43
W44
SF-1
SF10
SF4
SF6
SF61
TK-3
tk-18
tk-21
tk-37
tk-4
tk-7
SV-5
SV-8
R-3
R-5
R-8
12
13
TK4
TK7
1
2
HU1
HU2
HU3
subf-a
subf-b
subf-c
13
15A
96
Permit
Baseline
Year
1990
1990
1985
1985
1985
1985
1986
1990
1990
1990
1990
1992
1992
1992
1985
1985
1985
1985
1985
1986
1986
1986
1986
1986
1985
1985
1985
1985
1985
1985
1988
1988
1988
1988
1988
1989
1989
1990
1990
1990
1990
1992
1992
1992
1993
1993
1993
1981
1981
1981
Review
Year
1995
1995
1995
1995
1995
1995
1989
1994
1996
1996
1992
1998
1998
1998
1998
1998
1998
1998
1998
1998
1998
1998
1998
1998
1997
1997
1997
1997
1997
1997
1992
1992
1995
1995
1995
1997
1997
1996
1996
1994
1994
1998
1998
1998
1994
1994
1994
1995
1995
1995
Baseline
Median
12.4
30
25
15
1
3.5
1.76
3
0
6
7.95
1
1
1
45.06
5.5
13.1
18
9.5
0.3
0.35
1
0.2
4.35
18
12
4.5
9
1.6
6.5
6.3
8
2.95
3.25
31.8
0.3
37
2.19
3.1
6.6
0.15
8.64
1
8.68
2.3
3
7.7
7
10
2.75
Post-
Mining
Median
0
0
6
9
0
0
0
0
0
5.35
16
0
0
0
13.89
2.2
3.9
21.3
12.7
0.1
0.07
0.1
2.2
2.2
12.4
21.7
0.5
4
0.42
0
3.6
7.7
0.1
1.1
27.4
0.56
43.94
0.42
0
0
0
7.15
2.11
8.74
4
2
1.8
0
0
0
% Change
In Median
-100.00%
-100.00%
-76.00%
-40.00%
-100.00%
-100.00%
-100.00%
-100.00%
N/A
-10.83%
101.26%
-100.00%
-100.00%
-100.00%
-69.17%
-60.00%
-70.23%
18.33%
33.68%
-66.67%
-80.00%
-90.00%
1000.00%
-49.43%
-31.11%
80.83%
-88.89%
-55.56%
-73.75%
-100.00%
-42.86%
-3.75%
-96.61%
-66.15%
-13.84%
86.67%
18.76%
-80.82%
-100.00%
-100.00%
-100.00%
-17.25%
111.00%
0.69%
73.91%
-33.33%
-76.62%
-100.00%
-100.00%
-100.00%
Baseline
Upper
Limit
19.42
40.68
33.45
18.38
1
5.05
2.38
3.61
0.49
6.98
13.93
1.46
1.44
1.55
57.49
12.62
19.84
30.22
20.93
0.38
0.81
1.62
2.53
6.77
20.48
17.36
6.45
11.74
2.24
9.14
8.64
12.62
4.49
4.73
38.86
0.56
46.79
2.68
5.63
9.83
0.7
13.55
1.83
11.41
3.67
4.51
9.58
11.97
16.1
4.6
Baseline
Lower
Limit
5.38
19.32
16.55
11.62
1
1.95
1.14
2.39
-0.49
5.02
1.97
0.54
0.56
0.45
32.63
-1.62
6.36
5.78
-1.93
0.22
-0.11
0.38
-2.13
1.93
15.52
6.64
2.55
6.26
0.96
3.86
3.96
3.38
1.4
1.76
24.73
0.04
27.21
1.7
0.57
3.37
-0.4
3.72
0.17
5.94
0.93
1.49
5.82
2.03
3.9
0.9
Post-
Mining
Upper
Limit
0
0
9.27
12.93
0.11
0
0.13
0
0
6.19
21.7
0
0
0
23.21
6.34
5.52
30.02
18.91
0.17
0.1
0.52
3.7
7.32
17.59
27.46
2.02
5.32
0.66
0
5.17
16.99
0.85
1.62
35.05
1.19
57.55
0.68
0
0
0
10.99
2.54
12.1
4.56
3.48
3.37
0
0
0.66
Post-
Mining
Lower
Limit
0
0
2.73
5.07
-0.11
0
-0.13
0
0
4.51
10.3
0
0
0
4.57
-1.62
2.28
12.58
6.49
0.03
0.04
-0.32
0.7
-2.92
7.21
15.94
-1.02
2.68
0.18
0
2.03
-1.59
-0.65
0.58
19.75
-0.07
30.33
0.16
0
0
0
3.31
1.68
5.38
3.44
0.52
0.23
0
0
-0.66
Evaluation
4
4
3
2
3
4
3
4
4
2
2
4
4
4
3
2
3
2
2
3
2
2
2
2
2
2
3
3
3
4
2
2
3
3
2
2
2
3
4
4
4
2
2
2
2
2
3
4
4
3
us ;
B-30
Appendix B
nil i i in iiiiiiiiiiti1 in,. ,ii; i:i::,a ...... .' ti
<:t ..... ini: ..... JiiiiiHBi'F: ซ!** Mi/
- ii iiiyiiiBii , I: i \ >t\ oil ,.i i
iiiil ami |
-------
Coal Remining BMP Guidance Manual
Permit ID
Clinton-2
Clinton-3
Fayette-1
Fayette-2
Fayette-3
Fayette-4
Fayette-5
Fayette-6
Fayette-7
Fayette-8
Fayette-9
Fayette-1 0
Fayette-1 1
Fayette-1 2
Fayette-1 3
Fayette-1 4
Fayette-1 5
Fayette-1 6
Greene-1
Greene-2
lndiana-1
lndiana-2
ndiana-3
Indiana-4
Monitoring
Point ID
97
SNW1A
GR-9
SEH-31
SHE-30
mp-4
mp-5
mp-6
mp-8
HU-1
MS100
MP6
mp-4
mp-hua
MP-1
MP48
MP49
MP-1 5
MP-28
mp-1
mp-11
mp-2
mp29
Mp68
D5
mp-1 9
mp-57
mp-60
mp56
MD1/MD2
MD8/BS29
MP-42
MP-8
MP-51
hu1
H
J
K
L
M
N
O
MP15
MP5
1 (A)
2(B)
3(0
4(D)
1
MP51
Permit
Baseline
Year
1981
1981
1988
1990
1990
1989
1989
1989
1989
1984
1988
1988
1988
1988
1988
1989
1989
1988
1990
1989
1989
1989
1991
1991
1991
1991
1991
1991
1991
1991
1991
1994
1994
1987
1989
1988
1988
1988
1988
1988
1988
1988
1988
1988
1992
1992
1992
1992
1992
1992
Review
Year
1995
1996
1993
1993
1993
1993
1993
1993
1993
1992
1995
1993
1998
1998
1994
1996
1996
1994
1998
1992
1992
1992
1998
1997
1995
1998
1998
1998
1998
1995
1995
1996
1996
1988
1994
1995
1995
1995
1995
1995
1995
1995
1997
1997
1998
1998
1996
1998
1998
1998
Baseline
Median
5
36
8
16.2
1
2.5
2
1
2
27.5
40
0.9
105
45.25
6.1
53.95
10.1
6.85
26.46
16.03
8.88
1.35
4.13
0.8
1.5
0
1.7
8.8
7.7
2.8
1.1
0.9
28.6
0.01
51.5
27.3
14.6
3.6
4.2
3.1
0.8
0.01
8.1
31.5
0
93.2
55.8
16.5
16.1
14.9
Post-
Mining
Median
0
13.5
0.75
12.4
3
0.5
0
0
0.2
22.75
0.1
0.44
35.07
35.07
9.48
69.4
19.5
8.64
50.6
3.72
1.81
0.99
6.6
0.36
1.6
0
11.5
11.2
25.3
0
1.2
0.3
44.8
0
3.25
37.9
16.5
5.7
0.25
16.5
0.1
0
3.05
35.7
0
21.7
45
4.5
13.05
0
% Change
In Median
-100.00%
-62.50%
-90.63%
-23.46%
200.00%
-80.00%
-100.00%
-100.00%
-90.00%
-17.27%
-99.75%
-51.11%
-66.60%
-22.50%
55.41%
28.64%
93.07%
26.13%
91.23%
-76.79%
-79.62%
-26.67%
59.81%
-55.00%
6.67%
N/A
576.47%
27.27%
228.57%
-100.00%
9.09%
-66.67%
56.64%
-100.00%
-93.69%
38.83%
13.01%
58.33%
-94.05%
432.26%
-87.50%
-100.00%
-62.35%
13.33%
N/A
-76.72%
-19.35%
-72.73%
-18.94%
-100.00%
Baseline
Upper
Limit
6.56
45.33
12.58
26.28
1.24
3.13
2.42
1
2.21
32.88
56.59
2.17
151.13
58.47
8.73
86.49
15.76
10.13
54.68
18.5
15.66
1.79
10.56
1.63
2.43
0.51
3.08
20.18
15.13
8.94
2.05
1.52
42.45
0.01
68.92
35.46
19.67
4.24
6.23
5.31
1.58
0.05
11.35
58.16
0.8
143.58
94.21
26.01
19.58
20.26
Baseline
Lower
Limit
3.44
26.67
3.42
6.12
0.76
1.87
1.58
1
1.79
22.12
23.41
-0.37
58.87
32.03
3.47
21.41
4.44
3.57
-1.76
13.56
2.1
0.91
-2.3
-0.03
0.57
-0.51
0.32
-2.58
0.27
-3.34
0.15
0.28
14.75
0.01
34.08
19.14
9.53
2.96
2.17
0.89
0.02
-0.03
4.85
4.84
-0.8
42.82
17.39
6.99
12.62
9.54
Post-
Mining
Upper
Limit
0
16.85
3.68
17.13
4.06
0.51
0
0
0.2
29.15
1.58
0.78
54.5
54.5
32.43
90.48
28.01
18.11
69.93
5.56
4.61
1.44
9.07
0.78
2.21
0
27.76
28.36
49.2
0
1.53
0.91
48.7
0
5.85
49.63
32.77
9.35
2.89
23.26
0.18
0
3.65
61.41
0.37
36.23
55.96
6.93
18.6
0
Post-
Mining
Lower
Limit
0
10.15
-2.18
7.67
1.94
0.49
0
0
0.2
16.35
-1.38
0.09
15.64
15.64
-13.47
48.32
10.99
-0.83
31.27
1.88
-1
0.53
4.13
-0.06
0.99
0
-4.76
-5.96
1.4
0
0.87
-0.31
40.9
0
0.65
26.17
0.23
2.05
-2.39
9.74
0.02
0
2.45
9.99
-0.37
7.17
34.04
2.07
7.5
0
Evaluation
4
3
2
2
1
3
4
4
3
2
3
2
3
2
2
2
2
2
2
3
2
2
2
2
2
4
2
2
2
4
2
2
2
4
3
2
2
2
2
1
2
4
3
2
2
3
2
3
2
4
Appendix B
B-31
-------
Coal Rgminins BMP Guidance Manual
t!
""iP'i
liri'
iE','1!
' -
i
Til
nip
111
Permit ID
Jafferson-2
Jefferscn-3
Jefferson-5
Jefferson-6
Jefferson-7
Lawrence-1
Somarset-1
Somerset-2
Venango-1
Washing-
ton-1
Washing-
on-2
Washing-
on-3
Washing-
on-4
Washing-
on-5
Washing-
on-6
Washing-
on-7
Westmore-
and-1
Westmore-
and-2
Westmora-
and-3
Westmore-
and-4
Westmore-
and-5
Westmore-
and-6
/Vestmore-
nd-7
/Vestmore-
nd-8
Monitoring
Point ID
MP52
MP-1 3
HU-1
HU-2
MP-33
MP-8B
S-25
s-34
MP-1
1
SP16
1
1
HU1
A
CV103
CV4
MP-1
MP-2
d-1
D5
sela
MP10
MP7
MP9
S8
CP2
Culvert
MD-1
MD-3
MD-4
MD-6
MD-7
HU-1
M
N
MP-3
MP-4
MP-4
Permit
Baseline
Year
1992
1986
1989
1989
1989
1989
1993
1993
1991
1992
1989
1993
1989
1986
1985
1985
1985
1989
1989
1987
1992
1995
1984
1984
1984
1985
1986
1986
1986
1986
1986
1986
1986
1986
1985
1985
1986
1986
1987
Review
Year
1998
1996
1992
1992
1998
1998
1998
1998
1995
1998
1998
1998
1994
1993
1998
1998
1998
1998
1998
1996
1997
1998
1993
1993
1993
1994
1990
1986
1990
1990
1990
1990
1990
1996
1993
1993
1991
1991
1998
Baseline
Median
12.1
7.16
1
5.5
12.71
29
4.7
7.7
1.8
4.5
1
20
25.8
26.1
19.6
580
100
151.65
132
2.4
40
0.38
13.95
6.25
0.29
31.5
1
1
7
2.05
4.5
41.5
29.8
106
12.92
3.38
4.25
61.1
2
Post-
Mining
Median
3.8
6
0
0.4
4
27.63
8.6
0
0.2
0
11.75
9.8
20
83.83
4.75
500
90
34.7
0
1.2
30
0
8.3
16.9
0.9
8.1
0.75
1
3
0
3
0
6
69.95
11.7
0.65
1
120
0
% Change
In Median
-68.60%
-16.20%
-100.00%
-92.73%
-68.53%
-4.72%
82.98%
-100.00%
-88.89%
-100.00%
1075.00%
-51.00%
-22.48%
221.19%
-75.77%
-13.79%
-10.00%
-77.12%
-100.00%
-50.00%
-25.00%
-100.00%
-40.50%
170.40%
210.34%
-74.29%
-25.00%
0.00%
-57.14%
-100.00%
-33.33%
-100.00%
-79.87%
-34.01%
-9.44%
-80.77%
-76.47%
96.40%
-100.00%
Baseline
Upper
Limit
20.76
9.74
2.8
27.34
13.93
37.1
11.03
12.74
2.6
6.98
1.57
27.51
39.92
34.32
25.02
648.27
148.38
218.62
155.67
2.4
49.12
1.27
18.1
16.73
0.52
40.8
1.35
1.34
27.11
16.21
8.3
105.9
55.12
162.68
20.99
6.16
5.23
93.89
2
Baseline
Lower
Limit
3.44
4.58
-0.8
-16.34
11.5
20.9
-1.63
2.66
1
2.02
0.43
12.49
11.68
17.88
14.18
511.73
51.62
84.68
108.73
2.4
30.88
-0.52
9.8
-4.23
0.05
22.2
0.65
0.66
-13.11
-12.11
0.7
-22.9
4.48
49.32
4.85
0.59
3.27
28.31
2
Post-
Mining
Upper
Limit
5.3
7
0
0.6
7.79
46.59
12.13
2.35
0.91
0
19.53
12.03
62.86
113.59
7.94
500
96.36
49.26
0
1.52
34.06
0
12.32
21.18
1.31
18.08
1.03
1.54
4.22
0
4.22
0
8.84
92.5
14.3
1.38
1.41
148
0
Post-
Mining
Lower
Limit
2.3
5
0
0.2
0.21
8.67
5.07
-2.35
-0.51
0
3.97
7.57
-22.86
54.06
1.56
500
83.64
20.14
0
0.88
25.94
0
4.28
12.62
0.49
-1.88
0.47
0.46
1.78
0
1.78
0
3.16
47.4
9.1
-0.08
0.59
92
0
Evaluation
2
2
4
2
3
2
2
3
3
4
1
3
2
1
3
3
2
3
4
3
2
4
2
2
2
3
2
2
2
4
2
4
2
2
2
2
3
2
4
B-32
Appendix B
-------
Coal Remining BMP Guidance Manual
Permit ID
Westmore-
land-9
Westmore-
land-10
Westmore-
land-1 1
Westmore-
land-12
Westmore-
land-13
Westmore-
Iand-14
Westmore-
land-15
Westmore-
land-1 6
Westmore-
land-17
Westmore-
land-1 8
Westmore-
land-1 9
Westmore-
land-20
Westmore-
land-21
Westmore-
land-22
Monitoring
Point ID
MP-46
MP-47
MP-51
MP-52
MP-56
MP-60
MP-A
MP12
MP3
MP-1
MP-2
MP-3
MP-4
MP-5
MP-6
MP-A
MP-B
MP-C
MP-D
mp-a
mp-b
HU-1
MP-5A
SLK-GW-2
7
mp-8
SW18
1
2
3
MP16
MP5
MP6
mp-7
MP3
103
69
mp-13
mp-16
Permit
Baseline
Year
1987
1987
1987
1987
1987
1987
1987
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1988
1989
1989
1988
1988
1994
1990
1989
1989
1989
1989
1993
1993
1993
1991
1992
1994
1994
1994
1994
Review
Year
1993
1993
1993
1993
1993
1993
1995
1995
1992
1995
1995
1995
1995
1995
1995
1995
1995
1995
1995
1993
1993
1995
1995
1999
1995
1993
1995
1995
1995
1999
1999
1999
1998
1997
1998
1998
1998
1998
Baseline
Median
78.5
102.7
3.95
1.19
8.2
8.1
9.3
6.9
371.33
4
0.88
2.99
4
1.1
4.7
0.06
0
0.18
0
1.1
4.8
43.6
3
1.9
2.75
1.2
2.5
2.5
2.8
1.5
1.4
1.2
3.05
1
8.3
35.3
3.45
0.5
Post-
Mining
Median
84.5
288.1
1.72
3.5
11.05
5.25
2.9
7.2
321.4
0
2.9
5.1
0.54
5.1
8.1
2.19
2.19
1.5
0.2
0.8
0.5
31.62
0.31
0.4
8.3
0
0.48
2.78
1.4
1.7
0.2
0.1
1.22
8.62
0
0
0
0
% Change
In Median
7.64%
180.53%
-56.46%
194.12%
34.76%
-35.19%
-68.82%
4.35%
-13.45%
-100.00%
229.55%
70.57%
-86.50%
363.64%
72.34%
3550.00%
N/A
733.33%
N/A
-27.27%
-89.58%
-27.48%
-89.67%
-78.95%
201.82%
-100.00%
-80.80%
11.20%
-50.00%
13.33%
-85.71%
-91.67%
-60.00%
762.00%
-100.00%
-100.00%
-100.00%
-100.00%
Baseline
Upper
Limit
98.75
140.31
4.62
1.63
11.49
9.71
11.76
19.55
474.26
12.01
1.32
5.21
7.9
4.79
7.53
2.19
0.78
0.54
0.06
1.39
6.11
65.28
3.82
2.38
3.58
1.38
3.19
3.22
5.78
1.74
1.99
1.97
4.04
1.93
12.16
50.21
12.47
1.08
Baseline
Lower
Limit
58.25
65.09
3.28
0.74
4.91
6.49
6.84
-5.75
268.4
-4.01
0.43
0.77
0.1
-2.59
1.87
-2.08
-0.78
-0.19
-0.06
0.81
3.49
21.92
2.18
1.42
1.92
1.02
1.81
1.78
-0.18
1.26
0.81
0.43
2.06
0.07
4.44
20.39
-5.57
-0.08
Post-
Mining
Upper
Limit
105.99
360.96
3.63
5.93
23.83
9.55
4.92
11.58
386.85
0
4.15
6.05
0.93
7.38
11.7
4.34
3.42
2.64
0.38
2.22
1.72
38.41
0.52
0.71"
10.69
0
0.79
4.92
2.44
2.53
1.09
1.03
2.39
16.27
0
0.4
0
0
Post-
Mining
Lower
Limit
63.01
215.24
-0.19
1.07
-1.73
0.95
0.88
2.82
255.95
0
1.65
4.15
0.15
2.82
4.5
0.03
0.95
0.36
0.02
-0.62
-0.72
24.83
0.1
0.09
5.91
0
0.16
0.63
0.35
0.87
-0.69
-0.83
0.05
0.96
0
-0.4
0
0
Evaluation
2
1
2
2
2
2
3
2
2
4
1
2
2
2
2
2
1
2
2
2
3
2
3
3
1
4
3
2
2
2
2
2
2
2
4
3
4
4
Appendix B
B-33
-------
Coal Reminins BMP Guidance Manual
The site-by-site statistical comparisons and mine compliance history suggest that renaming is
conducted with little risk of worsening water quality. However, those data do not provide
insights into the broader overall, statewide water quality impacts. The calculations in Table B.2
are derived from the summary numbers for each water quality parameter in Table B.I. The
baseline median loads and post-mining median loads for all discharges are each totaled, and then
the sum of the baseline load is subtracted from the post-mining load. Table B.2 shows the results
in pounds per day (Ibs/day) and the percent change in median loads for the cumulative effects of
all the remming discharges. The summary numbers shown in Table B.2 provide insights that are
not readily evident from the statistical summaries. For example, the first discharge listed in
Table B.I (permit Allegheny-1, MP ID 10) showed no statistical difference in load despite the
fact that the post-mining median load was 2.5 times higher than the baseline median load. The
Summations depicted in Table B.2 show that even though some median loads have increased,
overall there has been a decrease in load, particularly acid load. The decreases on a yearly basis
"are substantial. Table B.2 suggests that renaming has decreased the acid load to streams in
Pennsylvania's bituminous coal region by over 5.8 million pounds per year. The annual
j
reductions in metals loads are more modest, but nonetheless important. Iron, manganese and
aluminum loads have been reduced by 189,000, 11,400, and 116400 Ibs/yr respectively. These
calculations confirm that there has been a substantial cumulative improvement in water quality
across the bituminous region as a result of remining.
Table B.2 : Summary of load data for select water quality parameters (PA Remining
Database).
Parameter
Acidity
Aluminum
Iron
Manganese
#of
Mines
109
57
104
75
#of
Discharges
236
121
220
164
Total Baseline
Median Load
26,092
702
1,485
247
Total Post-
Mining Load
10,174
399
968
216
Total Change in
Load (Ibs/day)*
-15,918
-302
-517
-31
% Change in
Median*
-61
-43.09
-35
-13
ฃ Negative numbers indicate a reduction in load
In addition to showing the overall environmental benefits of remining, the
documentation of
B-34
Appendix B
'l!l!,':ih! " II'A1 (It
'"' '- ''if' "
: ;
-------
Coal Remining BMP Guidance Manual
BMPs used upgradient from discharges has permitted an evaluation of the effectiveness of
individual and composite BMPs. This is the largest database currently available for evaluation of
BMP effectiveness. Twelve BMPs were selected for evaluation because they were commonly
used or there is a potential for increased use in the future. These BMPs are listed below and are
defined in Section 6 of this manual. The number of discharges affected by each BMP are
indicated in parentheses:
Surface regrading of spoil (156)
Revegetation (177)
Deep mine daylighting (170)
Special handling of acid-forming materials (80)
Alkaline addition at < 100 tons/acre (67)
Special water handling facilities (23)
Passive treatment system construction (2)
Coal refuse removal (9)
Biosolids application (6)
Mining high alkaline strata (13)
Alkaline addition at > 100 tons/acre (11)
On-site alkaline redistribution (6)
Table B.3 shows the BMPs affecting each discharge point. Multiple BMPs are routinely used in
an attempt to improve discharges. Evaluation of the effectiveness of these BMPs in terms of
observed outcome and statistical analysis is presented in Section 6.
Table B.3: BMPs affecting each Monitoring Point
Permit ID
Allegheny- 1
Allegheny-2
Allegheny-3
Allegheny-4
Monitoring Point
ED
10
2
S-6
S-7
d-lp
BS12
BMPs Applied
Surface regrading and Surface revegetation
Surface regrading and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Appendix B
B-35
-------
Coal Remining BMP Guidance Manual
!!B Fi1!!
Permit ID
Allegheny-5
Armstrong-1
Armstrong-2
Armstrong-3
Armstrong-4
Armstrong-5
Armstrong-6
Armstrong-?
Armstrong-?
Armstrong-8
Armstrong-9
Armstrong- 10
Armstrong- 1 1
Armstrong- 12
Monitoring Point
ID
MD1
MD2
MP-2
1A
D-l
D-112
D-4
w-lA
w-2A
w-3A
GK-13
GK-17
MP-2
1
MP14
MP15
MP17
MP21
MP22
MP23
MP24
c3-a
md-2
HU1
C-ll
S-20
HU1
mp2
mph
BMPs Applied
Special handling of acid-forming material, Surface regrading, and Surface
revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Surface regrading and Surface revegetation
Alkaline addition (less than 100 tons/acre) and Daylighting deep mines
Alkaline addition (less than 100 tons/acre) and Daylighting deep mines
Alkaline addition (less than 100 tons/acre) and Daylighting deep mines
Daylighting deep mines and Special handling of acid-forming material
Daylighting deep mines and Special handling of acid-forming material
Daylighting deep mines and Special handling of acid-forming material
Surface regrading and Surface revegetation
Surface regrading and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Construction of special water
landling facilities, Daylighting deep mines, and Special handling of acid-
brming material
Daylighting deep mines, Special handling of acid-forming material,
Surface regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material,
Surface regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
egrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material,
Surface regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
egrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material,
Surface regrading, and Surface revegetation
Passive treatment system construction, Surface regrading, and Surface
evegetation
Coal refuse removal, Special handling of acid-forming material, Surface
egrading, and Surface revegetation
Daylighting deep mines and Special handling of acid-forming material
Special handling of acid-forming material, Surface regrading, and Surface
evegetation
Daylighting deep mines and Other (see comment field)
)aylighting deep mines and Other (see comment field)
Daylighting deep mines, Surface regrading, and Surface revegetation
pecial handling of acid-forming material, Surface regrading, and Surface
evegetation
pecial handling of acid-forming material, Surface regrading, and Surface
evegetation
B-36
Appendix B
-------
Coal Reminins BMP Guidance Manual
Permit ID
Armstrong- 13
Armstrong- 14
Armstrong- 15
Armstrong- 16
Armstrong- 17
Armstrong- 18
Beaver- 1
Butler- 1
Butler-2
Butler-3
Butler-4
Butler-5
Cambria-1
Clarion- 1
Monitoring Point
ID
41
48
Unit 2
1
V2
HU1
HU1
Dl
S-10
5W
2W
SAW
8W
S-116
S-13
S-200
S-91
S-95/96
DR2
1
MP9
MP13
SP-1
SP-28
SP-5
SP-6
BMPs Applied
Biosolids application, Daylighting deep mines, Surface regrading, and Surface
revegetation
Daylighting deep mines, Passive treatment system construction, and Surface
revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Mining and handling of highly alkaline strata, Other
(see comment field), Surface regrading, and Surface revegetation,
Surface regrading and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, and Other
(see comment field)
Daylighting deep mines, Other (see comment field), Surface regrading, anc
Surface revegetation
Construction of special water handling facilities, Daylighting deep mines,
Surface regrading, and Surface revegetation
Surface regrading and Surface revegetation
Surface regrading and Surface revegetation
Surface regrading and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
handling of acid-forming material, Surface regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, and Surface
revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, and Surface
revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, and
Surface revegetation
Alkaline addition (less than 100 tons/acre), Construction of special water
handling facilities, and Daylighting deep mines
Alkaline addition (less than 100 tons/acre) and Daylighting deep mines
Alkaline addition (less than 100 tons/acre), Construction of special water
handling facilities, Daylighting deep mines, and Mining and handling of
lighly alkaline strata
Alkaline addition (less than 100 tons/acre), Construction of special water
landling facilities, Daylighting deep mines, and Mining and handling of highly
alkaline strata
Construction of special water handling facilities, Surface regrading, and Surface
revegetation
Construction of special water handling facilities, Surface regrading, and Surface
revegetation
Construction of special water handling facilities, Surface regrading, and Surface
revegetation
Construction of special water handling facilities, Surface regrading, and
Surface revegetation
Appendix B
B-37
-------
Coal Rgmining BMP Guidance Manual
'51,:'
Ill
Permit ID
C!arion-2
Clarion-3
Clarion-4
Clarion-5
Clarion-6
CIearfield-1
Clearfield-2
Clearfield-3
Clearileld-4
Clearfield-5
Monitoring Point
ID
1
RH-78
1
2
DR-1
1
2
3
unit 1
W10
W42
W43
W44
SF-1
SF10
SF4
SF6
SF61
TK-3
tk-18
tk-21
tk-37
tk-4
tk-7
SV-5
SV-8
BMPs Applied
Alkaline addition (less than 100 tons/acre), Construction of special water
handling facilities, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Construction of special water handling facilities, Daylighting deep mines,
Surface regrading, and Surface revegetation
Construction of special water handling facilities, Daylighting deep mines,
Surface regrading, and Surface revegetation
Alkaline addition (greater than 1 00 tons/acre), Special handling of acid-forming
material, Surface regrading, and Surface revegetation
Surface regrading and Surface revegetation
Surface regrading and Surface revegetation
Surface regrading and Surface revegetation
Other (see comment field)
Alkaline addition (less than 100 tons/acre), Surface regrading, and Surface
revegetation
Alkaline addition (less than 100 tons/acre), Surface regrading, and Surface
revegetation
Alkaline addition (less than 100 tons/acre), Surface regrading, and Surface
revegetation
Alkaline addition (less than 100 tons/acre), Surface regrading, and Surface
revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Other (see
comment field), Special handling of acid-forming material, Surface regrading,
and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Other (see
comment field), Special handling of acid-forming material, Surface regrading,
and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Other (see
omment field), Special handling of acid-forming material, Surface regrading,
nd Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Other (see
omment field), Special handling of acid-forming material, Surface regrading,
and Surface revegetation
urface revegetation
urface revegetation
urface revegetation
urface revegetation
urface revegetation
Jiosolids application and Surface revegetation
Alkaline addition (less than 100 tons/acre), Special handling of acid-forming
naterial, and Surface regrading
\lkaline addition (less than 100 tons/acre), Special handling of acid-forming
naterial, and Surface revegetation
B-38
Appendix B
-------
Coal Reminine BMP Guidance Manual
Permit ID
Clearfield-6
Clearfield-7
Clearfield-8
Clearfield-9
Clearfield-10
Clearfield-ll
Clinton- 1
Clinton-2
Fayette-1
Monitoring Point
ID
R-3
R-5
R-8
12
13
TK4
TK7
1
2
HU1
HU2
HU3
subf-a
subf-b
subf-c
96
97
13
15A
SNW1A
GR-9
SEH-31
SHE-30
mp-4
mp-5
mp-6
BMPs Applied
Daylighting deep mines, Mining and handling of highly alkaline strata, anc
Surface regrading
Daylighting deep mines, Mining and handling of highly alkaline strata, and
Surface regrading
Coal refuse removal, Daylighting deep mines, and Mining and handling of
highly alkaline strata
Daylighting deep mines, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Alkaline addition (greater than 100 tons/acre), Biosolids application, Surface
regrading, and Surface revegetation
Alkaline addition (greater than 100 tons/acre), Biosolids application, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, and Special
landling of acid-forming material
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, and Special
handling of acid-forming material
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation '
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Mining and
landling of highly alkaline strata, Surface regrading, and Surface revegetation
Alkaline addition (less than 1 00 tons/acre), Daylighting deep mines, Mining and
handling of highly alkaline strata, Surface regrading, and Surface revegetation
Alkaline addition (less than 1 00 tons/acre), Daylighting deep mines, Mining and
landling of highly alkaline strata, Surface regrading, and Surface revegetation
Alkaline addition (greater than 100 tons/acre), Surface regrading, and Surface
revegetation
Alkaline addition (greater than 100 tons/acre), Surface regrading, and Surface
revegetation
Alkaline addition (greater than 100 tons/acre), Daylighting deep mines, and
Surface revegetation
Alkaline addition (greater than 1 00 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (greater than 100 tons/acre), Biosolids application,
Daylighting deep mines, and Surface regrading
Alkaline addition (greater than 100 tons/acre), Daylighting deep mines, and
Special handling of acid-forming material
Alkaline addition (greater than 100 tons/acre), Special handling of acid-forming
material, and Surface revegetation
Alkaline addition (greater than 100 tons/acre), Special handling of acid-forming
material, and Surface regrading
Daylighting deep mines and Surface revegetation
Daylighting deep mines and Surface revegetation
Daylighting deep mines and Surface reveaetation
Appendix B
B-39
-------
'Si;'"
'i'1''
I'ซk '4,. ! ,'"f'',!
ii'"1 !ซ' i:'
.. 'l!v 0 11, iifs, ;i.'i
Coal Remining BMP Guidance Manual
''!"' Uy\^Kl ,, uiiiiill; U '''
Permit ID
Fayette-2
Fayette-3
Fayette-4
Fayette-5
Fayelte-6
Fayette-7
Fayette-8
Fayette-9
Fayette-10
Fayette-1 1
Fayette-1 2
Fayette-1 3
Fayette-1 4
Fayette-1 5
'" : : '-
Fayette-1 6
Greene- 1
Greene-2
Indiana-I
Jlf ,;;[ ]:;! I1,';, ! '1 i;"!1"'1
ikilil < il'I'Ii i ik ! ! , !,! M,'1!,;'1;, 11,!,, ,;ป
Monitoring Point
ED
mp-8
HU-1
MS100
MP6
mp-4
mp-hua
MP-1
MP48
MP49
MP-15
MP-28
mp-1
mp-11
mp-2
mp29
Mp68
D5
mp-1 9
mp-57
mp-60
mp56
MD1/MD2
MD8/BS29
MP-42
MP-8
MP-51
hul
H
' :'"!U"", ' ti'U. !' .; / . I/If ' '.; "&: * Illif; , :J 11:' ti:i:" '''[;.' ^vr- :> :''rป i-y'ill
BMPs Applied
Daylighting deep mines and Surface revegetation
Alkaline addition (less than 100 tons/acre), Biosolids application, Coal refuse
removal, Special handling of acid-forming material, Surface regrading, and
Surface revegetation
Coal refuse removal, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Coal refuse removal, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Coal refuse removal, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, and Surface
revegetation
Daylighting deep mines, Special handling of acid-forming material, and Surface
revegetation
Daylighting deep mines and Surface revegetation
Daylighting deep mines, Other (see comment field), and Special handling of
acid-forming material
Daylighting deep mines
Daylighting deep mines, Surface regrading, and Surface revegetation
Construction of special water handling facilities, Daylighting deep mines,
Special handling of acid-forming material, Surface regrading, and Surface
revegetation
Construction of special water handling facilities, Daylighting deep mines,
Special handling of acid-forming material, Surface regrading, and Surface
evegetation
Construction of special water handling facilities, Daylighting deep mines,
Special handling of acid-forming material, Surface regrading, and Surface
evegetation
Construction of special water handling facilities, Daylighting deep mines,
Special handling of acid-forming material, Surface regrading, and Surface
evegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
)aylighting deep mines
Daylighting deep mines
Surface regrading and Surface revegetation
Mining and handling of highly alkaline strata, Special handling of acid-forming
material, Surface regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre) and Davlightingjdeep mines
B-40
Appendix B
-------
Coal Remining BMP Guidance Manual
Permit ID
Indiana-2
Indiana-3
Indiana-4
Jefferson-2
Jefferson-3
Jefferson-5
Jefferson-6
Jefferson-7
Lawrence- 1
Somerset- 1
Somerset-2
Monitoring Point
ID
J
K
L
M
N
0
1
2
1(A)
2(B)
3(C)
4(D)
1
MP51
MP52
MP-13
HU-1
MP-33
MP-8B
S-25
s-34
MP-1
1
SP16
1
BMPs Applied
Alkaline addition (less than 100 tons/acre) and Daylighting deep mines
Alkaline addition (less than 100 tons/acre) and Daylighting deep mines
Alkaline addition (less than 100 tons/acre) and Daylighting deep mines
Alkaline addition (less than 100 tons/acre) and Daylighting deep mines
Alkaline redistribution from on-site sources and Daylighting deep mines
Alkaline addition (less than 100 tons/acre) and Daylighting deep mines
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Other (see
comment field), Special handling of acid-forming material, Surface regrading,
and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Other (see
comment field), Special handling of acid-forming material, Surface regrading,
and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
handling of acid-forming material, Surface regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
handling of acid-forming material, Surface regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
handling of acid-forming material, Surface regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, and Surface
revegetation
Alkaline redistribution from on-site sources, Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
handling of acid-forming material, Surface regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
handling of acid-forming material, Surface regrading, and Surface revegetation
Other (see comment field) and Surface regrading
Surface regrading and Surface revegetation
Surface regrading and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Other (see
comment field), Surface regrading, and Surface revegetation
Construction of special water handling facilities, Other (see comment field),
Special handling of acid-forming material, Surface regrading, Surface
revegetation
Daylighting deep mines, Special handling of acid-forming material, Mining and
handling of highly alkaline material
Appendix B
B-41
-------
Coal Reminins BMP Guidance Manual
"lk liiLEI" ill
IHil, I'l'-l'i '!' ilisJ"1
.il"!1!!'1:"!' ill"!'!''!1 I!, ,'!!!!ป":
Permit ED
Venango-1
Washington- 1
Washington-2
Washington-3
Washington-4
Washington-5
Washington-6
Washington-?
Westmoreland-
1
Westmoreland-
2
Westmoreland-
3
Westmoreland-
4
Westmoreland-
5
Westmoreland-
6
Westmoreland-
7
Westmoreland-
8
Monitoring Point
ED
1
HU1
A
CV103
CV4
MP-1
MP-2
d-1
D5
sela
MP10
MP7
MP9
S8
CP2
Culvert t
MD-1
MD-3
MD-4
MD-6
MD-7
HU-1
M
N
MP-3
MP-4
MP-4
BMPs Applied
Construction of special water handling facilities, Daylighting deep mines,
Special handling of acid-forming material, Surface regrading, and Surface
revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines
Daylighting deep mines, Mining and handling of highly alkaline strata, and
Special handling of acid-forming material
Daylighting deep mines, Mining and handling of highly alkaline strata, and
Special handling of acid-forming material
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines
Daylighting deep mines, Special handling of acid-forming material, and Surface
regrading
Alkaline addition (less than 1 00 tons/acre), Daylighting deep mines, and Specia
handling of acid-forming material
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, and Special
handling of acid-forming material
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, and Specia
mndling of acid-forming material
Alkaline addition (less than 100 tons/acre) and Daylighting deep mines
Coal refuse removal, Surface regrading, and Surface revegetation
Coal refuse removal, Surface regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
landling of acid-forming material, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
landling of acid-forming material, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
landling of acid-forming material, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
landling of acid-forming material, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Special
landling of acid-forming material, and Surface revegetation
Daylighting deep mines
Coal refuse removal and Daylighting deep mines
Daylighting deep mines
Daylighting deep mines, Special handling of acid-forming material, Surface
egrading, and Surface revegetation
Daylighting deep mines, Special handling of acid-forming material, Surface
egrading, and Surface revegetation
Daylighting deep mines
B-42
Appendix B
-------
Coal Remining BMP Guidance Manual
Permit ID
Westmoreland-
9
Westmoreland-
10
Westmoreland-
11
Westmoreland-
12
Westmoreland-
13
Westmoreland-
14
Westmoreland-
15
Westmoreland-
16
Westmoreland-
17
Westmoreland-
18
Monitoring Point
ID
MP-46
MP-47
MP-51
MP-52
MP-56
MP-60
MP-A
MP12
MP3
MP-1
MP-2
MP-3
MP-4
MP-5
MP-6
MP-A
MP-B
MP-C
MP-D
mp-a
mp-b
HU-1
MP-5A
SLK-GW-27
mp-8
SW18
1
BMPs Applied
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Alkaline addition (less than 100 tons/acre), Daylighting deep mines, Surface
regrading, and Surface revegetation
Surface regrading and Surface revegetation
Surface regrading and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Daylighting deep mines, Surface regrading, and Surface revegetation
Construction of special water handling facilities, Daylighting deep mines, and
Surface revegetation
Other (see comment field), Surface regrading, and Surface revegetation
Construction of special water handling facilities, Daylighting deep mines,
Special handling of acid-forming material, Surface regrading, and Surface
revegetation
Appendix B
B-43
-------
Coat Remining BMP Guidance Manual
Permit ID
Westmoreland-
19
Westmoreland-
20
Westmoreland-
21
Westmoreland-
22
Monitoring Point
ID
2
3
MP16
MP5
MP6
mp-7
MP3
103
69
mp-13
mp-16
BMPs Applied
Construction of special water handling facilities, Daylighting deep mines,
Special handling of acid-forming material, Surface regrading, and Surface
revegetation
Construction of special water handling facilities, Daylighting deep mines,
Special handling of acid-forming material, Surface regrading, and Surface
revegetation
Daylighting deep mines
Daylighting deep mines
Daylighting deep mines
Construction of special water handling facilities, Daylighting deep mines,
Surface regrading, and Surface revegetation
Daylighting deep mines
Alkaline redistribution from on-site sources, Special handling of acid-forming
material, Surface regrading, and Surface revegetation
Alkaline redistribution from on-site sources, Special handling of acid-forming
material, Surface regrading, and Surface revegetation
Alkaline redistribution from on-site sources, Special handling of acid-forming
material, and Surface revegetation
Alkaline redistribution from on-site sources, Special handling of acid-forming
material. Surface regrading, and Surface revegetation
B-44
Appendix B
-------
Coal Reminine BMP Guidance Manual
Appendix C: Interstate Mining Compact Commission
Solicitation Sheet Response Summary
Appendix C
-------
Coal Rtimining BMP Guidance Manual
11 I
Appendix C
-------
Coal Remitting BMP Guidance Manual
Interstate Mining Compact Commission Solicitation Sheet
Summary of Responses Received from 20 States
Prepared by DynCorp, I & ET
On September 3, 1998, the Interstate Mining Compact Commission distributed a Solicitation
Sheet to member states in support of continuing efforts to collect data and information required
for proposal of a renaming subcategory under 40 CFR 434. The Solicitation Sheet was intended
to gather information required to assess current industry renaming activity and potential. The
Solicitation also was intended to target sources of data and information available for the
development of BMP guidance.
Twenty-two responses from twenty states have been received, and are summarized in the tables
included in this Appendix. The information has been used to develop a profile of the renaming
industry, determine the potential for remining activity, and provide an indication of the types and
efficiencies of BMPs currently being implemented during remining operations.
Specific questions that were included in the solicitation are outlined below:
1) Types of remining permits issued: Number of traditional Rahall permits
Number of non-Rahall remining permits
Other remining-type projects
% total permits characterized as remining
State's definition of "Remining"
State's interpretation of "Pre-existing discharge"
Appendix C
C-l
-------
Coal Rkmining BMP Guidance Manual
2) Characteristics of remitting operations:
Coal refuse piles, surface mines, underground mines
Permits with discharges not meeting BAT standards
Geographic distribution of remining sites
Recent remining permit issuance (12 months)
3) Characteristics of potential remining operations: coal refuse piles, surface mines,
underground mines, discharges
r
4) Range of BMPs used in remining operations
5) Indication of available data or information regarding implementation of BMPs
!
6) Indication of state's experience with BMPs in terms or success or failure
7) Stream miles impacted by abandoned mine drainage
8) Industry profile of remining operations: mining companies, employees, annual
production, potential coal reserves for remining
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C-2
Appendix C
-------
Coal Reminins BMP Guidance Manual
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Information reported as submitted by State.
See additional footnotes (attached).
N/A = Not applicable.
? = Unknown
= No response.
Appendix C
C-3
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.Coal Remining BMP Guidance Manual
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Appendix C
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Coal Reminine BMP Guidance Manual
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Appendix C
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Coal Remining BMP Guidance Manual
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Appendix C
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Coal Reminine BMP Guidance Manual
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Coal Remining BMP Guidance Manual
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Coal Remining BMP Guidance Manual
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Appendix C
C-13
-------
Coal Remining BMP Guidance Manual
ill
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i
C-14
Appendix C
-------
Coal Remining BMP Guidance Manual
5
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=
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1
1
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1
1
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p
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0
,-
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CO
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B. Exclusion of Infiltrating Ground Water
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CM
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1
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5
1
1
1
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o
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CD
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0
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1
1
1
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s
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1
1
0
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1
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c
s
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1
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c. Sealing of auger holes
-
o
0
B
S
1
1
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0
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7. Sealing of underground mine entries (via flooding)
0
CO
o
CO
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:
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1
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b. Limestone Drains
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o
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0
1
cc
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1
0
0
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o
o
,
o
1
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1
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0
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9. Construction of high-water retention soils
o
o
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0
1
1
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1
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0
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0
1
1
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1
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CO
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CO
o
o
1
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o
CO
1
1
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o
CO
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10
o
,
o
1
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I
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2. Coal cumbustion wastes
o
o
,
o
1
1
1
0
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CO
T-
o
o
t
1
1
1
0
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8. Induced Alkaline recharge
0
o
o
1
0
1
1
0
0
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1. Trenches
o
o
o
1
0
1
1
0
,
0
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CM
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o
:
1
!
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1
1
0
o
tn
C. Special handling of AFMs
(O
CM
O
O
!
1
s
'
1
1
0
0
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3
t
Appendix C
C-15
-------
Coal Remining BMP Guidance Manual
Ill IIMti
I
ill in nil
1111
lliliii
ill
(Illlllllll
Illlllllll
in ill ...... i
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3
sr
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C. a:
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In |
C-16
Appendix C
-------
Coal Remining BMP Guidance Manual
3
5
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p
saipiirj uo|sj9A
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w
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or
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Elimination of closed contour depressions & pits
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Clays & other natural materials
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5
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Appendix C
C-17
-------
Coal Reminins BMP Guidance Manual
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C-18
Appendix C
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Coal Remining BMP Guidance Manual
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.Coal Remining BMP Guidance Manual
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-------
Coal Remining BMP Guidance Manual
Question 6: What has your state's experience been with these BMPs in
terms of their success or failure of implementation?
State
Response
Alaska
Alabama
Colorado
Illnois
Indiana
Kentucky (1) -
(SMRE)
Kentucky (2) -
(CWA)
Maryland
Missouri
Mississippi (1 ) -
(CWA)
Mississippi (2)
Montana
North Dakota
New Mexico
Ohio
Pennsylvania
Tennessee
Texas
Utah
Virginia
West Virginia
Wyoming
None.
No response.
Generally successful. Failures have been in some of the details which were corrected with one-time
maintenance. Water treatment projects have shown limited success.
No response.
While several BMPs have been employed effectively they have not been allowed as an exception to
normal NPDES limitations as provided by Rahall Amendment. Majority of applications have been in true
AML projects and not "remining" senarios.
Success or failure of BMPs for both Title IV and V programs is indirectly reflected in the "closure" of AML
projects & the approval of complete bond releases in this state. These final actions would not occur if the
above-utilized BMPs were unsuccessful.
The issuance of a KPDES permit does not require specific knowledge of the types and number of these
defined BMPs. Therefore, the division of Water cannot provide non quality related data.
Just beginning to implement.
To date the constructed wetlands have not obtained the desired water quality.
Fair to good & site specific results.
No response.
Silt fencing, bales, matting has worked well.
No response.
No response.
Application of PFBC by-product during reclamation has proven successful. We applied 125 tons/acre of
by-product, plus 50 tons/acre of yard-waste compost to the mine site. Vegetation has been established.
pH of interstitial pore waters is near neutral (6.5-7.0). Ne elevated concentration of As, Se, Hg, or Pb were
detected. However SO4 + B concentration have risen, which may be of concern. (Same as Pennsylvania)
Reqradina of old spoils: hiahlv successful. Often will promote runoff and reduce infiltration. Davliqhtinq of
deep mines: successful when alkaline overburden is encountered in dayliahtinq or surface runoff is
restored.
Alkaline addition: a mixed baa. Can work, but often there is not enouqh alkaline material added to be
effective.
Special Handlina: can reduce acidity, but cannot produce alkaline water in the absence of calcareous
materials.
Reveqetation: an unqualified success.
Biosolids: very successful in promotina veaetation.
Hvdroaeolodic controls: jury still out. We're looking at it.
The most successful BMPs implemented in TN are: limestone drains; surface diversions; geochemical
amendments; and special handling of acid forming materials.
No response.
No response.
Generally, when BMPs are used, we see an improvement in water quality. This can be documented
through water monitoring reports that are submitted to the Division on a quarterly basis and then
compared to baseline data. Only in a couple of instances did we observe no change in water quality.
Too early to tell.
BMPs have been sucessfully implemented. In Wyoming the primary water quality concern is with
sediment. AMD problems associated with coal mining are virtually non-existant.
Information reported as submitted by State.
Appendix C
C-21
-------
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Coal Remitting BMP Guidance Manual
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C-22
Appendix C
-------
Coal Reminine BMP Guidance Manual
Question 7. Does your state maintain a listing or inventory
of the number of stream miles impacted by AMD.
(i.e., EPA 303(d) listing)? If available, please provide mileage.
State
Stream
Miles
AK
AL
65
CO
Yes
IL
NA
IN
No
KY(I-SMRE)
600
KY(2-CWA)
600
MD
430
MO
52 miles classified, 87 miles unclassified
MS(1-CWA)
No
MS(2-SMCRA)
MT
ND
NM
0
OH
1,500
PA
3,000
TN
1,750
TX
0
UT
VA
No
WV
2,225
WY
0
Total
9,709
Information reported as submitted by State.
NA = Not Available.
- = No Response.
Appendix C
C-23
-------
Ill," i'i III 11 ' ' I I11 III, 111' in"! I'
Coal Remining BMP Guidance Manual
II1 Ill
C-24
Appendix C
IS ' II jfl "II Hi
-------
Coal Remining BMP Guidance Manual
Question 8. What is the industrial profile of your state's remining operations?
If exact numbers are unknown, please provide estimates.
State
Number of
mining companies
with remining permits
Total employment
at remining operations
(number of employees)
Annual coal production
from remining sites
(tons)
Estimated coal reserves
that could be remined
(tons)
AK
AL
CO
IL
IN
0
20
0
35
2
0
Unk
0
70
N/A
0
Unk
0
200,000
720,000
0
Unk
Unk
10,000,000
N/A
KY(1-SMRE)
KY(2-CWA)
MD
MO
MS(1-CWA)
MS(2-SMCRA)
MT
4
13
2
0
0
0
Unk
150
0
0
0
Unk
650,000
0
0
0
Unk
Unk
Unk
Unk
0
ND
NM
OH
PA
TN
TX
UT
VA
WV
WY
Totals
0
3
50
10
0
0
3
8
0
150
0
Unk
2,345
75-100
0
0
300
Unk
0
2,940 - 2,965
0
Unk
17,530,000
3,000,000
0
0
3,000,000 +
Unk
0
25,100,000
0
Unk
100,000,000 +
50,000,000
0
Unk
Unk
Unk
Unk
160,000,000
Information reported as submitted by State.
Unk = Unknown.
N/A = Not Applicable.
= No Response.
Appendix C
C-25
-------
i ill 111" 1 Mil "If lilil i
ill! ""Ill
Coal Rcmining BMP Guidance Manual
"I
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HI 111(11
C-26
Appendix C
------- |