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Coal Remining Best Management Practices Guidance Manual


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

Coal Remining BMP Guidance Manual

Acknowledgments
This manual was developed under the direction of William A. Telliard of the Engineering and Analysis Division (EAD) 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 this 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 EPA may decide to follow the draft guidance provided in this document, or to act at variance with the guidance, based on its analysis of the specific facts presented. This draft guidance is being issued in connection with the proposed amendments to the Coal Mining Point Source Category.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

Coal Remining BMP Guidance Manual

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Coal Remining BMP Guidance Manual

TABLE OF CONTENTS
Page SECTION OUTLINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii GLOSSARY AND ACRONYMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxvii INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 INTRODUCTION TO BEST MANAGEMENT PRACTICES . . . . . . . . . . . . . . . . . . . . . 21 Section 1.0 1.1 1.2 1.3 Section 2.0 2.1 2.2 2.3 2.4 2.5 Section 3.0 Section 4.0 Section 5.0 Section 6.0 Section 7.0 Hydrologic and Sediment Control BMPs . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Control of Infiltrating Surface Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 Control of Infiltrating Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-31 Sediment Control and Revegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-69 Geochemical Best Management Practices . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 Alkaline Addition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-29 Induced Alkaline Recharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-63 Special Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-79 Bactericides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-127 Operational Best Management Practices . . . . . . . . . . . . . . . . . . . . . . . . . . Passive Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Integration of Best Management Practices . . . . . . . . . . . . . . . . . . . . . . . . . Efficiencies of Best Management Practices . . . . . . . . . . . . . . . . . . . . . . . . . Best Management Practices - Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 4-1 5-1 6-1 7-1

APPENDICES
Appendix A: EPA Coal Remining Database - 61 State Data Packages . . . . . . . . . . . . . . A-1 Appendix B: Pennsylvania Remining Site Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1 Appendix C: Interstate Mining Compact Commission Solicitation Sheet Response Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

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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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Site Characteristics and BMP Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regional Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BMP Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 24 26 36 37 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
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Site Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.1 Implementation Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Daylighting of Underground Mines . . . . . . . . . . . . . . . . . . . . . . . . . . Sealing and Rerouting of Mine Water from Abandoned Workings . . . Highwall Drains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pit Floor Drains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grout Curtains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ground Water Diversion Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.2 Verification of the Degree of Success or Failure . . . . . . . . . . . . . . . . Daylighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sealing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Drains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grout Curtains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diversion Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Implementation Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.3 Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sediment Control and Revegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Site Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.1 Implementation Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Site Stabilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Revegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Direct Revegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Channel, Ditch, and Gully Stabilization . . . . . . . . . . . . . . . . . . . . . . . Channel Linings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Check Dams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Silt Fences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gradient Terraces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.2 Verification of Success or Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . Implementation Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.3 Literature Review/Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-33 1-34 1-34 1-39 1-44 1-47 1-50 1-53 1-55 1-56 1-57 1-57 1-57 1-58 1-58 1-59 1-60 1-60 1-64 1-65 1-65 1-65 1-66 1-67 1-69 1-69 1-70 1-72 1-75 1-75 1-78 1-79 1-80 1-81 1-83 1-84 1-84 1-86 1-86 1-88 1-88 1-89 1-92 1-92 1-93

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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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-51
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2.4

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 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 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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Case Study 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bactericides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Site Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.1 Implementation Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.2 Verification of Success or Failure . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.3 Literature Review/Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Case Study 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2-118 2-118 2-120 2-120 2-121 2-121 2-122 2-124 2-127 2-127 2-127 2-129 2-130 2-131 2-131 2-135 2-136 2-137 2-137 2-137 2-138 2-138 2-139 2-139 2-139 2-140 2-140

Section 3.0 Operational Best Management Practices . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 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
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Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3-29 3-30 3-30 3-31 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 Pyrolusite? 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 6.1 6.2 6.3
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Efficiencies of Best Management Practices . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3 Pennsylvania DEP – Remining Site Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5 Observed Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6 Predicted Efficiencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26 6.3.1 Statistical Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-26
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6.5

6.3.2 Statistical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Individual BMPs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BMP Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.1 Observed Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acidity Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Iron Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manganese Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aluminum Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sulfate Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flow Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.2 Predicted Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BMPs Implemented Alone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BMP Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regrading and Revegetation . . . . . . . . . . . . . . . . . . . . . . . . . Daylighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regrading, Revegetation, and Daylighting . . . . . . . . . . . . . . . Coal Refuse Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overall Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-28 6-28 6-38 6-59 6-59 6-60 6-61 6-64 6-65 6-67 6-68 6-70 6-70 6-74 6-75 6-78 6-80 6-82 6-84 6-85 6-86 6-89

Section 7.0 Best Management Practices - Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 Table Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-18

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Page

Introduction
Table 1: Table 2: Table 3: Table 4: Table 5: Table 6: Table 7: Table 8: Number of Stream Miles Impacted by AMD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 AML Inventory Totals of 4 Major AML Problem Types in Appalachia and the U.S, as of September, 1998 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Coal Production by State (Short Tons) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 State by State Profile of Remining Operations. . . . . . . . . . . . . . . . . . . . . . . . . 11 Types of Remining Permits Issued by State . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Characteristics of Existing Remining Operations by State . . . . . . . . . . . . . . . . 13 Potential Remining Operations by State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Pennsylvania Remining Permits Which Required Treatment, June, 1997 . . . . . . 17

Section 1.0 Hydrologic and Sediment Control Best Management Practices
Table 1.1.3a: Table 1.1.3b: Table 1.1.3c: Table 1.3.1a: Synopsis of Water Quality Data at Case Study 1 Site . . . . . . . . . . . . . . . . . . Synopsis of Water Quality Data at Case Study 2 Site . . . . . . . . . . . . . . . . . . Synopsis of Flow and Pollutant Loading at Case Study 3 Site. . . . . . . . . . . . Revegetation Practices and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-23 1-24 1-27 1-77

Section 2.0 Geochemical Best Management Practices
Table 2.1a: Table 2.1b: Table 2.1c: Table 2.1d: Table 2.1e: Table 2.2.1a: Table 2.2.1b: Table 2.2.1c: Table 2.2.1d: Table 2.2.1e: Table 2.2.1f: Table 2.3.3a: Minimum Overburden Analysis Drill Hole Spacing Requirements, by State. Number of Acres per Overburden Analysis Hole. . . . . . . . . . . . . . . . . . . . . . Number of Acres per Overburden Analysis Hole Based on SOAP Applications Received in 1993. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overburden Interval Sampling Requirements. . . . . . . . . . . . . . . . . . . . . . . . Compositing of Too Many 1-foot Intervals Can Underestimate Acid Producing Potential. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Distribution, Type and Amount of Alkaline Materials Used. . . . . . . . . . . . . Example Analyses of Coal Ash. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Percentage of Sites Producing Net Alkaline Drainage by Net NP without Thresholds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Percentage of Sites Producing Net Alkaline Drainage by Total NP without Thresholds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Percentage of Sites Producing Net Alkaline Drainage by Net NP with Thresholds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Percentage of Sites Producing Net Alkaline Drainage by Total NP with Thresholds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Water Quality for Wells at the Case Study 2 Site . . . . . . . . . . . . . . . . . . . . 2-15 2-17 2-17 2-25 2-26 2-34 2-35 2-41 2-41 2-41 2-42 2-73

List of Tables

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EPA Remining 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

Table 2.4a:

Section 3.0 Operational Best Management Practices
Table 3.1a: Table 3.1b: Table 3.1c: Table 3.1d: Summary of Overburden Analysis Data from a Surface Mine Located in Logan County, West Virginia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8 Total Sulfur in Stratigraphic Sections Enclosing the Coal at a Remining Site in Westmoreland County, Pennsylvania. . . . . . . . . . . . . . . . . . 3-10 Coal and Enclosing Strata Sulfur Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20 Overburden Analysis from an Acid-producing Underground Mine in Armstrong County, PA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21

Section 4.0 Passive Treatment
Table 4.1: Table 4.3: OLC Sizing Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20 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: Table 6.2b: Table 6.3a: Table 6.3b: Table 6.3c: Table 6.3d: Table 6.3e: Table 6.3f: Table 6.3g: Table 6.3h: Pennsylvania Remining Permits, Summary of Observed Water Quality Results by Individual BMP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8 PA Remining Study: Observed Effects of BMP Groupings on Discharges. . . 6-17 PA Remining Study: Predicted Odds of Acidity Improvement or Elimination. 6-32 PA Remining Study: Predicted Odds of Iron Improvement or Elimination. . . 6-33 PA Remining Study: Predicted Odds of Manganese Improvement or Elimination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34 PA Remining Study: Predicted Odds of Aluminum Improvement or Elimination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-35 PA Remining Study: Predicted Odds of Sulfate Improvement or Elimination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-36 PA Remining Study: Predicted Odds of Flow Improvement. . . . . . . . . . . . . . 6-37 Analysis of Discrete Groups based on Observed Acidity Results Using Regrading and Revegetation as Reference Group.. . . . . . . . . . . . . . . . . . . . . 6-41 Analysis of Discrete Groups based on Observed Iron Results Using Regrading and Revegetation as Reference Group.. . . . . . . . . . . . . . . . 6-42
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Table 6.3i:

Analysis of Discrete Groups based on Observed Manganese Results Using Daylighting as Reference Group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3j: Analysis of Discrete Groups based on Observed Aluminum Results Using Daylighting as Reference Group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3k: Analysis of Discrete Groups based on Observed Sulfate Results Using Daylighting as Reference Group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3l: Analysis of Discrete Groups based on Observed Flow Results Using Daylighting as Reference Group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3m: Analysis of Discrete Groups based on Observed Acidity Results Using Daylighting as Reference Group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3n: Analysis of Discrete Groups based on Observed Iron Results Using Daylighting as Reference Group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3o: Analysis of Discrete Groups based on Observed Manganese Results Using Daylighting as Reference Group.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3p: Analysis of Discrete Groups based on Observed Aluminum Results Using Daylighting as Reference Group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3q: Analysis of Discrete Groups based on Observed Sulfate Results Using Daylighting as Reference Group.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3r: Analysis of Discrete Groups based on Observed Flow Results Using Daylighting as Reference Group.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3s: Analysis of Discrete Groups based on Observed Acidity Results Using Regrading, Revegetation, and Daylighting as Reference Group. . . . . . Table 6.3t: Analysis of Discrete Groups based on Observed Iron Results Using Regrading, Revegetation, and Daylighting as Reference Group. . . . . . Table 6.3u: Analysis of Discrete Groups based on Observed Manganese Results Using Regrading, Revegetation, and Daylighting as Reference Group. . . . . . Table 6.3v: Analysis of Discrete Groups based on Observed Aluminum Results Using Regrading, Revegetation, and Daylighting as Reference Group. . . . . . Table 6.3w: Analysis of Discrete Groups based on Observed Sulfate Results Using Regrading, Revegetation, and Daylighting as Reference Group. . . . . . Table 6.3x: Analysis of Discrete Groups based on Observed Flow Results Using Regrading, Revegetation, and Daylighting as Reference Group. . . . . . Table 6.4a: Types of Mining and Minimal BMPs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-43 6-44 6-45 6-46 6-47 6-48 6-49 6-50 6-51 6-52 6-53 6-54 6-55 6-56 6-57 6-58 6-74

Section 7.0
Table 7a: Table 7b: Table 7c: Table 7d: Table 7e: Table 7f: Table 7g: Table 7h:
List of Tables

Unit Costs of Best Management Practices
Alkaline Addition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3 Anoxic Limestone Drains (ALDs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4 Ash Fill Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5 Bactericides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6 Check Dams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7 Constructed Wetlands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8 Daylighting .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9 Diversion Ditch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10
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Table 7i: Table 7j: Table 7k: Table 7l: Table 7m: Table 7n: Table 7o:

Diversion Wells, Alkalinity Producing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Drains, Pit Floor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regrading of Abandoned Mine Spoil/Highwalls . . . . . . . . . . . . . . . . . . . . . . Revegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sealing and Rerouting of Mine Water from Abandoned Workings . . . . . . . . Silt Fences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Special Handling for Toxic and Acid Forming Materials . . . . . . . . . . . . . . . .

7-11 7-12 7-13 7-14 7-15 7-16 7-17

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List of Figures
Page

Introduction
Figure 1: Figure 2: Figure 3: Figure 4: Figure 5: Figure 6: Figure 7: Figure 8: Figure 9: Percentage of Total Number of Rahall Permits Issued by State . . . . . . . Status of 260 Pennsylvania Remining Permits . . . . . . . . . . . . . . . . . . . . Percentage of Streams with a pH less than 6.0 for 24 Watersheds in the Appalachian Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Percentage of Surface Water Sample Stations with Sulfate Greater than 75 mg/L for 24 Watersheds in the Appalachian Basin . . . . . . . . . . . . . . Statigraphic Variation of Sulfur Content of 34-Coal Beds of the Cental Appalachians . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Example of Steep Topography and High Relief in Southern West Virginia Showing Multiple Contour Strip Mines on Steep Slopes . . . . . Example of Moderate Slopes and Broader Valleys and Hilltops in West-central Pennsylvania Showing Small Area Mines . . . . . . . . . . . . . Topographic Map Illustrating Contour Surface Mining . . . . . . . . . . . . . Topographic Map Illustrating Area Surface Mining . . . . . . . . . . . . . . . . 15 17 28 29 30 32 33 34 35

Section 1.0 Hydrologic and Sediment Control Best Management Practices
Figure 1.1.1a: Figure 1.1.1b: Figure 1.1.3a: Figure 1.1.3b: Figure 1.2a: Figure 1.2.1a: Figure 1.2.1b: Figure 1.2.1c: Figure 1.2.1d: Figure 1.2.1e: Figure 1.2.1f: Figure 1.2.1g: Figure 1.2.1h: Figure 1.2.1i: Figure 1.2.1j: Figure 1.2.3a: Figure 1.2.3b: Diagram of the Location of Surface Cracks Between Highwall and Backfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 Schematic Diagram of a Cap Instilled on a Reclaimed Surface Mine. . . 1-12 Acidity Concentration at Discharge Point MD-12 Before and After Remining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-25 Acidity Load at Discharge Point MD-12 Before and After Remining . 1-25 Typical Correlation Between Discharge Flow and Pollutant Loading in Mine Drainage Discharges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-33 Example of Mine Subsidence and Exposed Fractures . . . . . . . . . . . . 1-36 Exposed Auger Holes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-40 Example of a Mine Entry Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-41 Example of a Virginia-Type Mine Entry Seal . . . . . . . . . . . . . . . . . . . 1-42 Example of a Mine Drain System . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-43 Cross Section of an Example Chimney Drain . . . . . . . . . . . . . . . . . . . 1-45 Cross Section of Horizontal Highwall Drains . . . . . . . . . . . . . . . . . . 1-46 Pit Floor Drain Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-48 Pit Floor Drain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-49 Common Drilling Pattern for Pressure Grouting Wells. . . . . . . . . . . . 1-52 Change in Flow Over Time (Case Study Discharge MP-1). . . . . . . . . 1-61 Change in Flow Over Time (Case Study Discharge MP-4) . . . . . . . . 1-61

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Figure 1.2.3c: Figure 1.2.3d: Figure 1.3.1a: Figure 1.3.1b:

Flow Rate Reduction, Pre- and Post-Remining Periods (Case Study Discharge MP-4). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flow Rate Reduction, Pre- and Post-Remining Periods (Case Study Discharge MP-6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Example of a Rock Check Dam . . . . . . . . . . . . . . . . . . . . . . . . . . . . Example of a Gabion Check Dam . . . . . . . . . . . . . . . . . . . . . . . . . .

1-62 1-63 1-82 1-83

Section 2.0 Geochemical Best Management Practices
Figure 2.2a: Figure 2.2.3a: Figure 2.2.3b: Figure 2.2.3c: Figure 2.3.1a: Figure 2.3.3a: Figure 2.3.3b: Figure 2.3.3c: Figure 2.4a: Figure 2.4b: Figure 2.4.1a: Figure 2.4.1b: Figure 2.4.1c: Figure 2.4.1d: Figure 2.4.1e: Figure 2.4.1f: Figure 2.4.3a: Figure 2.4.3b: Figure 2.4.3c: Figure 2.5a: Figure 2.5.3a:
xiv

Solubility of Calcium Carbonate in Water at 25OC as a Function of Partial Pressure of CO2.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-32 Water Quality Before and After Mining at the Keating #2 Site, Clinton, PA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-53 Water Quality Before and After Mining at the Case Study 2 Site . . . . 2-54 Water Quality at the Case Study 3 Site . . . . . . . . . . . . . . . . . . . . . . . 2-56 Alkaline Recharge Channels and Capped Acid-producing Material Pods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-65 Topography, Location of Recharge Trenches and Funnels, and Locations of Seeps (Case Study 1, Upshur County, WV) . . . . . . . . . 2-67 Plot of Acidity versus Time for Seep #2 at Case Study 1 Mine . . . . . 2-69 Map of Case Study 2 Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-72 Early Recommendation of the Pennsylvania Sanitary Water Board for Handling Sulfuritic Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-85 High and Dry Placement of Acidic Material . . . . . . . . . . . . . . . . . . . . 2-86 Overburden Handling Procedures Depending on the Stratigraphic Position of Acid-producing Materials . . . . . . . . . . . . . . . . . . . . . . . . 2-94 Overburden Handling Procedures Depending on the Stratigraphic Position of Acid-producing Materials. . . . . . . . . . . . . . . . . . . . . . . . . 2-94 Three-dimensional Conceptual View of High and Dry Placement of Acid-forming Materials.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-97 Projected Target Zone Determination for Placement of Acid Forming Material within the Backfill . . . . . . . . . . . . . . . . . . . . . . . . . 2-99 Schematic of Special Handling of Acid-forming Materials by the Submergence Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-106 Blending and Alkaline Redistribution Do Not Require the Isolation of Acid-forming Materials in Isolated Pads . . . . . . . . . . . . . . . . . . . 2-110 Distribution of Sulfur and Neutralization Potential for Bedrock at the Special Handling Site in Clarion County, PA. . . . . . . . . . . . . . . 2-112 Distribution of Sulfur and Neutralization Potential for Spoil in the Northern Hilltop where Bulldozers and Loaders Were Used . . . . . . 2-115 Distribution of Sulfur and Neutralization Potential for Spoil in the Southern Hilltop Where a Dragline was Used . . . . . . . . . . . . . . . . . 2-116 Rates of Pyrite Oxidation with and without Iron-oxidizing Bacteria . 2-128 Effect of Anionic Detergents on Acid Production from Pyritic Coal. . 2-132
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Coal Remining BMP Guidance Manual

Figure 2.5.3b: Figure 2.5.3c: Figure 2.5.3d:

Measured Profiles of Oxygen in Unsaturated Spoil . . . . . . . . . . . . . 2-133 Oxygen Cncentration with Depth in Coal Refuse in Pennsylvania and Ohio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-134 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: Figure 3.1b: Figure 3.1c: Relationship Between the Solubility of Calcium Carbonate and the Partial Pressure of Carbon Dioxide at 25EC. . . . . . . . . . . . . . . . . . . . . 3-6 Advective Impacts on Unreclaimed Mine Spoil . . . . . . . . . . . . . . . . . . 3-6 Potential Sources of Pit and Tipple Cleanings. . . . . . . . . . . . . . . . . . . . 3-9

Section 4.0 Passive Treatment
Figure 4.1a: Figure 4.1b: Figure 4.1c: Figure 4.1d: Figure 4.1e: Figure 4.1f: Anoxic Limestone Drain Construction . . . . . . . . . . . . . . . . . . . . . . . . . 4-6 Commonly Constructed Wetland Diagram. . . . . . . . . . . . . . . . . . . . . 4-12 Typical Wetland Cell Cross Section. . . . . . . . . . . . . . . . . . . . . . . . . . 4-13 Example of a Successive Alkalinity-Producing System Cell. . . . . . . . 4-16 Typical Alkalinity-Producing Diversion Wells. . . . . . . . . . . . . . . . . . . 4-25 Example of Water Intake Portion of an Alkalinity-Producing Diversion Well. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-26

Section 5.0 Integration of Best Management Practices
Figure 5.0a: Figure 5.0b: Water Table Suppression in Conjunction with Special Handling of Acidic Material. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 Optimal Location for Special Handling of Acidic and Alkaline Materials.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Section 6.0 Efficiencies of Best Management Practices
Figure 6.4a: Figure 6.4b: Figure 6.4c: Figure 6.4d: Figure 6.4e: Figure 6.4f: Impacts of BMP Combinations on Acidity Loading.. . . . . . . . . . . . . . Impacts of BMP Combinations on Iron Loading. . . . . . . . . . . . . . . . . Impacts of BMP Combinations on Manganese Loading. . . . . . . . . . . Impacts of BMP Combinations on Aluminum Loading. . . . . . . . . . . . Impacts of BMP Combinations on Sulfate Loading. . . . . . . . . . . . . . Impacts of BMP Combinations on Flow Rate. . . . . . . . . . . . . . . . . . . 6-61 6-63 6-65 6-66 6-68 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.

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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 preexisting 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.

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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. 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 and 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. 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+ 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 groundwater 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.

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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 the 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. 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. 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. Pyrolusite? 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. Remining: 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.

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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. 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.
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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 lbs/day: pounds per day
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lbs/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 Remining 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: C

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

C

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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C C C

Section 6.0 - detailing the efficiency of remining BMPs in regards to the water quality of pre-existing discharges; 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;

C C

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.

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 on how, when, and where to use them, and recommends maintenance procedures. However, the 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 sitespecific 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 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

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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.

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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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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 III 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 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 groundwater 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 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.

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 Stream Miles (Source A) Alabama Illinois Indiana Kentucky Maryland Missouri Ohio Pennsylvania Tennessee Virginia West Virginia Totals 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+ 510 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.
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NA = Not Available

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Abandoned Mine Land Program and AMLIS

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 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:
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? ? ? ? ? ? ? ? ?

Clogged Streams Dangerous Highwalls Dangerous Piles & Embankments Gases: Hazardous/Explosive Hazardous Water Bodies Portals Polluted Water: Human Consump. Surface Burning Vertical Openings

? ? ? ? ? ? ? ?

Clogged Stream Lands Dangerous Impoundments Dangerous Slides Hazard. Equip. & Facilities Ind./Residential Waste Polluted Water: Agri. & Ind. Subsidence Underground Mine Fires

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 Equipment/Facilities Highwalls Mine Openings Pits Slurry ? ? ? ? ? ? Industrial/Residential Waste Gob Haul Road Slump Spoil Areas 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
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between states. Table 2 lists inventories of abandoned mine land conditions in nine Eastern Coal Region states.

Table 2:
State

AML Inventory Totals of 4 Major AML Problem Types in Appalachia and the U.S., as of September, 1998 (OSMRE, 1998)
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 Dangerous slides (acres) 21 0 1,519 8 99 7 92 117 346 2,209 98% 2,253

Alabama Indiana Kentucky Maryland Ohio Pennsylvania Tennessee Virginia West Virginia Appalachia Total % of U.S. Total U.S. Total

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
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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 rule 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).

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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. West of Miss. U.S. Total 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 4,259,000 17,110,000 1,904,000 53,328,000 -8,907,000 4,495,000 57,220,000 279,035,000 159,418,000 105,923,000 403,934,000 206,281,000 462,994,000 669,274,000 4,678,000 71,520,000 3,300,000 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 1,089,932,000 131 272 27 12 12 191 3 349 25 1,602 149 77 1,716 112 1,828

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

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

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 4,160,000 401,000 41,005,000 27,025,000 29,580,000 29,154,000 1,621,000 51 1 2 3 14 28 39 3 529 2 18 4 8 6 6 81 11

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Coal Remining 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, IL) (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 “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 in the 1987 Rahall Amendment and this document refers to “ a coal 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 (IMCC) 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 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).

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Table 4: State by State Profile of Remining Operations (IMCC, 1998)

Number of mining companies with remining permits

Total employment at remining operations (Number of employees)

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 >25,100,000

Estimated coal reserves (tons)

Alabama 20 ND Alaska 0 0 Colorado 0 0 Illinois 35 70 Indiana 2 NA Kentucky 4 ND Maryland 13 150 Missouri 2 0 Mississippi 0 0 Montana 0 -New Mexico 0 0 Ohio 3 ND Pennsylvania 50 2,345 Tennessee 10 75 - 100 Texas 0 0 Utah 0 0 Virginia 3 300 West 8 ND Wyoming 0 0 Totals 150 >2,940-2,965 NA = Not Available; -- = No Response; ND = No Data.

ND 0 ND 10,000,000 NA ND ND ND ND -0 ND 100,000,000+ 50,000,000 0 ND ND ND ND >160,000,000

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.

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Table 5: Types of Remining Permits Issued by State (IMCC, 1998)

State

Number of Rahall Permits

Number of NonRahall Permits (a) 61 0 0 41 1 N/A 21 20 0 0 --ND 40 350-450 0 0 158 --692-792

“Other” Remining Permits/Projects (b) 1 0 15 0 1 1 0 0 0 14 --101 3 0 0 0 501 1 -638

Remining Permits (% of Total) ND 0 0 0 1 40 30 15 0 0 -0 60-70 95(c)/50(d) 60 0 0 75-80 0.4 --

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

(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 operations (i.e., refuse piles, surface mine, or underground mines).
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Table 6:

Characteristics of Existing Remining Operations by State (IMCC, 1998) Number of coal refuse piles Number of surface mine sites Active Mines Under Permit 54 0 0 1 34 1 17 2 1 11 0 2 1,278 135180 AML Projects Number of underground sites Active Mines Under Permit 13 0 0 0 2 2 21 0 0 1 0 1 655 210260 0 0 117 --130 0 32 107 1 -1,0451,095 0 N/A 104 --108 0 0 0 9 -632 0 N/A 2 --3 AML Projects Number of remining permits meeting BAT Active Mines Under Permit ND 0 0 0 0 5 2 0 0 0 0 0 616 0 AML Projects

State

Active Mines Under Permit 4 0 0 40 1 3 0 0 0 1 0 0 173 5-10

AML Projects

Alabama Alaska Colorado Illinois Indiana Kentucky Maryland Missouri Mississippi Montana New Mexico Ohio Pennsylvania Tennessee

1 0 4 0 0 1 -0 0 -0 -0 0

-0 12 0 ---0 0 -0 1 0 0

-0 2 0 ---0 0 -0 -2 0

1 0 0 0 ---0 0 -0 -0 0

Texas Utah Virginia West Virginia Wyoming Totals

0 5 33 1 -266-

0 0 38 --44

0 2 77 7 -1,622-

271 1,667 N/A = Not Applicable; -- = No Response; ND = No Data.

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Best estimates of potential remining activities according to IMCC member states are provided in Table 7.

Table 7:

Potential Remining Operations by State (IMCC, 1998) Number of coal refuse piles Number of surface mine sites Number of underground mined sites

Alabama Alaska Colorado Illinois Indiana Kentucky Maryland Missouri Mississippi Montana New Mexico Ohio Pennsylvania Tennessee Texas Utah Virginia West Virginia Wyoming Totals

1 3 ~400 30 150 ~200 10 0 0 1 N/A (1,095 acres) 858 (182 acres) 0 5 400-450 -0 2,058 - 2,108 and 1,277 acres

-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

-1 ~850 12 615 800 - 1,000 75 0 0 1 N/A 4,000 (31,587 acres) 800 0 32 800 -0 7,986 - 8,186 and 31,587 acres

-- = No Response N/A = Not Applicable

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Existing State Remining 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 IMCC 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

WV (2.42%) VA (0.91%)

AL (3.03%) KY (1.21%) MD (0.61%) OH (0.91%)

PA (90.91%)

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Below is a brief history of the development and requirements of each state’s 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 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 longterm 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-

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remining 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) Bituminous Region Anthracite Region 12 0 0 0 Totals 260 3 2 11

Permits Issued Currently Treating Forfeited due to AMD Required Treatment Figure 2:

248 3 2 11

Status of 260 Pennsylvania Remining Permits (IMCC, 1997)

1 % s i te s treating

1 % fo rfeiture sites

9 8 % n o t tre a t i n g

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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. 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 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

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, and offers reduced bonding rates for an NPDES remining permit. Currently, Maryland has

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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.

Kentucky

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
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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).

Alabama

Alabama has issued 10 permits with relaxed effluent limits for remining operations. To qualify for a remining permit an operator must show:

? ? ? ?

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).

?

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.

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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 remining 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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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 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) Stream sealing (gw) Underground mine daylighting (gw) Mine entry and auger hole sealing (gw) Highwall and pit floor drains (gw) Grout curtains (gw) Ground water diversion wells (gw) Advanced erosion and sedimentation controls (e&s)

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 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
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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 acidforming 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: C C C C 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

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loads discharging from remining sites. Passive treatment methods are discussed in Section 4.0 (Passive Treatment Technologies). Types of passive treatment include: C C C C C C C anoxic limestone drains constructed wetlands successive alkalinity-producing systems open limestone channels oxic limestone drains alkalinity-producing diversion wells pyrolusite? systems

Site Characteristics and BMP Selection
Factors that influence which BMPs can be employed effectively at remining sites include 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 these categories are examples of associated BMPs and some of their limitations:

Previous mining history ? ? 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.

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?

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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Regional Differences
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 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). 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 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 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.

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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.

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Figure 3:

Percentage of Streams with pH < 6.0 for 24 Watersheds in the Appalachian Basin (data from Wetzel and Hoffman, 1983).

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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).

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Figure 5:

Stratigraphic Variation of Sulfur Content of 34 Coal Beds of the Central Appalachians. (Figure from Cecil and others, 1985).

Hydrology The ground-water hydrology is similar throughout much of the Appalachian Plateau, however 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. 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

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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
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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.

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Figure 7:

Example of Moderate Slopes and Broader Valleys and Hilltops in Westcentral Pennsylvania Showing Small Area Mines.

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Figure 8:

Topographic Map Illustrating Contour Surface Mining.

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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.

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BMP Implementation
The best BMP plan may fail if it is not implemented as designed (e.g., conducted properly, 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 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 information should be sufficient to identify which strata will require handling, potential sources of ground water, probable reasons for existing AMD, the scope of previous mining, and other salient data. Site assessment will typically, at a minimum, require extensive field work and mapping, multiple bore holes with appropriate vertical sampling, ground-water level measurements, surface water flow measurements, and representative ground- and surface-water samples.

A BMP plan should be realistic. It should be appropriate to the site, workable in the field, 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 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.

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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C C C

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-thepipe 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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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., material weigh slips, receipts, laboratory analyses, etc.) where necessary. Guidelines for verification for each BMP category are provided in the appropriate section of this manual.

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 with all other factors being equal.

Monitoring and inspection of BMPs to verify site conditions and implementation should be a requirement of any remining operation. Verification includes: C C C C C C C C C C

Direct measurement of flow and water sampling for contaminant concentrations before, during, and after reclamation. Monitoring should continue beyond the initial water table re-establishment period (e.g., at least 2 years after backfilling). Evaluation of water quality and quantity data at hydrologically-connected units and/or discrete individual discharges, so trends caused by remining can be assessed. Hydrologic data should be reviewed with respect to climatic (i.e. precipitation) conditions. Assessment of deviations from the approved implementation plan. Inspection of critical stages of the BMP implementation plan, such as during special materials handling, alkaline addition, drain installation, or mine entry sealing. Inspection should assure, where required, proper maintenance is performed. Review of material weigh slips, receipts, laboratory analysis, and other necessary documentation. 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 physical and geologic conditions, and impacts of significant storm events.

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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.

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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. 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. 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. Int. J. Surf. Min. Reclam., v. 4, pp. 11-19. 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. 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. Plowman, W., 1989. New Light on an Old Problem. Game News, May 1989, 6pp. 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. 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. II. Mine Reclamation, Abandoned Mine Lands and Policy Issues. USBM IC 9184, pp.311-318.

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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 III and Office of Surface Mining, 1997. Cleaning Up Appalachian Polluted Streams. 1996 Progress Report, USEPA Region III 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.

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303(d)KY, 1998. 303(d) List of Waters for Kentucky. Kentucky Natural Resources and Environmental Protection Cabinet, Division of Water, June 1998. 303(d)TN, 1998. Proposed Final 1998 303(d) List. Tennessee Department of Environment and Conservation, Nashville, Tennessee, June 1998 (Revised July).

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Section 1.0:
Introduction

Hydrologic and Sediment Control BMPs

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 laterallymigrating 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 closedcontour 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 operations, 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.

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 across the mine surface enters the spoil through these exposed voids and flows rapidly downward 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.

Other researchers contend that mining may improve the recharge potential from undisturbed 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 in Indiana. It is important to note that these two studies did not address the impact of mining on the soil horizon as discussed by Razem (1983, 1984). Once infiltrating water has passed through the soil horizon, 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.

Strock (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 (38 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.
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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 (Cederstrom, 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
Spoil characteristics, such as hydraulic conductivity, porosity, and infiltration rates, are by-andlarge dependent on site-specific conditions. Even with site-specific testing, these parameters can 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 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 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 obey Darcy’s Law, invalidating the aquifer testing procedures.

Materials used in sealing or grouting may require analysis to ascertain their hydraulic properties, 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 to the approximate original contour or to at least achieve a more natural looking post-mining condition. In order to maximize the efficiency of this BMP, the spoil should be regraded in a manner which promotes runoff of precipitation and other surface water. This is achieved by creating slopes of a sufficient grade to induce runoff, but not to the degree that the runoff water velocity causes undue erosion.

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 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 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 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 reclaimed soil properties and those of undisturbed soils still exist 11 years after reclamation.

Potter and others (1988) observed that the saturated hydraulic conductivity of reclaimed topsoil 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 observed that subsoils composed of shale and clay spoils are 10 and 100 times less permeable than from natural subsoils, respectively. Thus, runoff from reclaimed mine spoils is much greater than natural soils. The reasons for these differences are attributed to decreased percentage of large pores resulting in density increases, loss of soil structure and reduced depths to low permeability layers (Silburn and Crow, 1984).

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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. Reaffecting 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 surfacewater 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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appreciably change. Because of this differential settling, it is common for linear surface gaps or cracks to run along or near this interface (Figure 1.1.1a). These cracks create an ideal infiltration 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 installation of diversion ditches above the highwall is an effective BMP to preclude recharge to the spoil from adjacent surface water runoff.

Figure 1.1.1a: Diagram of the Location of Surface Cracks Between Highwall and Backfill

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 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 erosionresistant 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 1.1.1b). 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 naturallyoccurring clay within a short hauling distance.

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Figure 1.1.1b: Schematic Diagram of a Cap Installed on a Reclaimed Surface Mine

The installation of low-permeability caps over the top of mine backfills can be an effective BMP for reducing surface-water infiltration. However, installation of these caps can be an expensive 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 10-10 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 10-8 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, 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.

These studies indicate that if a cap is placed on top of a reclaimed backfill, a significant reduction of surface-water infiltration can be achieved. For example, if a hypothetical unreclaimed and unvegetated site permits infiltration of 75 percent of the precipitation (this number is likely higher) and continues to allow 35 percent infiltration after it is regraded, the addition of an 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 the 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 lbs/day. However, with regrading and cap 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 lbs/day or 91.2 to 94.1 percent.

Revegetation

Revegetation of mine spoil can dramatically reduce the amount of surface water that would 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

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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.

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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 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 decrease over a similar distance.

Another method of stream sealing involves injecting polyurethane to grout targeted sections of streams. Similar 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 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 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 bed should be underlain with a liner material to preclude surface water infiltration. However, erosionresistant material should be placed over the top of the liner to prevent future liner breaching.

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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 C C C 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 C C C C 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 C C C 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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Revegetation C C Root systems should retain water and not provide infiltration pathways Select local and native plant species that will thrive and create a lush cover

Stream Sealing C C 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
Verification that 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 aspects of a BMP cannot be overstated. It is the role of the mine inspector to enforce the 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.

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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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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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 depending on climatic (e.g., precipitation) and hydrogeologic (spoil porosity and permeability, 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 sitespecific, it is recommended that implementation inspections of hydraulic control BMPs include the following: C C C C C C C C C

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 as well as individual discharges 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 Inspection of diversion ditches, caps and seals for leakage Inspection of vegetation for viability

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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 reestablishing 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 fractureflow 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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Case Study 1 (Appendix A, EPA Remining Database, 1999, PA(6))

This mine was located in Armstrong County, Pennsylvania where the remining was performed on 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. 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. 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 com

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