OFFICE OF SURFACE MINING 

REPORT ON OCTOBER 2000 

BREAKTHROUGH AT THE BIG BRANCH SLURRY IMPOUNDMENT 

Martin County Coal Corporation 

Big Branch Slurry Impoundment 

Martin County, Kentucky 

Kentucky Department for Surface Mining Reclamation and Enforcement 

Permit Number 680-8002 

Mine Safety and Health Administration 

Identification Number 1211-KY6-0035-01 

PREPARED BY

U.S. Department of the Interior 

Office of Surface Mining 

March 2002

OFFICE OF SURFACE MINING 

REPORT ON OCTOBER 2000 

BREAKTHROUGH AT THE BIG BRANCH SLURRY IMPOUNDMENT 

Martin County Coal Corporation 

Big Branch Slurry Impoundment 

Martin County, Kentucky 

Kentucky Department for Surface Mining Reclamation and Enforcement 

Permit Number 680-8002 

Mine Safety and Health Administration 

Identification Number 1211-KY6-0035-01 

PREPARED BY

U.S. Department of the Interior 

Office of Surface Mining 

March 2002
BLANK PAGE 
EXECUTIVE SUMMARY 

Introduction

The Office of Surface Mining’s (OSM) Lexington Field Office and the Appalachian Regional 

Coordinating Center (ARCC) have prepared this oversight report on selected portions of the 

Kentucky surface mining program, which was conditionally approved on May 18, 1982, under 

the federal Surface Mining Control and Reclamation Act of 1977 (SMCRA). In Kentucky, the 

Department for Surface Mining Reclamation and Enforcement (DSMRE) administers the 

regulatory program. Once a state is awarded regulatory primacy, OSM has the responsibility 

under SMCRA to conduct special investigations, program evaluations, and field inspections as 

necessary to assure the state program is being managed in accordance with the approved 

provisions. Under this unique partnership, OSM and DSMRE share responsibility for 

accomplishments as well as problems. Nonetheless, it is OSM’s role to investigate the Martin 

County Coal Corporation (MCCC) breakthrough in accordance with its oversight responsibility 

and record appropriate observations and recommendations. 

On October 11, 2000, an estimated 306 million gallons of water and coal slurry drained from

MCCC’s Big Branch impoundment into an adjacent underground mine. Approximately 245 

million gallons of the water and coal slurry discharged from the underground mine at the 

Number 2 North Portals and the South Mains Portal and entered the watersheds of Coldwater 

Fork and Wolf Creek. No personal injuries were reported, but the slurry affected over 75 miles 

of streams in Kentucky and West Virginia with the spill reaching as far as the Ohio River. 

Kentucky Governor Paul Patton declared a state of emergency in ten counties in northeast 

Kentucky. The parent company of MCCC, Massey Energy Company, has reported that as of 

July 31, 2001, 36.9 million dollars had been spent on the cleanup. Civil litigation is currently 

pending which involves numerous impacted citizens seeking damages from MCCC. 

This was the second major breakthrough event at this impoundment, the first having occurred in 

May 1994. Also, as a result of several breakthroughs over the last few years including some in 

Virginia, OSM announced on November 2, 2000, an action plan to assure that impoundment 

breakthroughs into the underground mine do not occur in the future. To accomplish the 

objectives spelled out in the OSM action plan, ARCC developed an implementation plan to 

complete the following three tasks: 

Task 1: Establish a regional impoundment technical committee to determine the factors 

contributing to the MCCC impoundment breakthrough. 

Task 2: Expand the technical committee to include state and the Federal Mine Safety and Health 

Administration (MSHA) technical representatives. The expanded committee, using their 

combined experience along with information gained from the Kentucky and Virginia 

experiences, will develop criteria that should be considered in reevaluating high-risk (high 

breakthrough potential) impoundments over or adjacent to underground mine workings. 

ii 
Task 3: Develop and implement individual field office work plans designed to minimize the 

potential for future impoundment leaks or breakthroughs into underground mine workings. 

This report is issued to complete Task 1. On July 27, 2001, ARCC issued Criteria for 

Evaluating the Potential for Impoundment Leaks into Underground Mines (Existing and 

Proposed Impoundments), to complete Task 2. The field offices in the Appalachian Region are 

in various stages of implementing Task 3. DSMRE, with assistance from OSM, is currently reevaluating all existing MSHA-class impoundments in Kentucky. As part of this initiative, 

DSMRE has taken the following actions: (1) implemented a plan for a joint OSM/DSMRE 

permit review and field inspection of each of the 117 MSHA-class impoundments in Kentucky, 

(2) identified all structures within 500 feet of an underground mine, (3) completed a risk 

assessment for breakthrough potential on each impoundment including those rated as “high 

breakthrough potential” by MSHA, (4) revised existing protocols regarding review and approval 

of slurry impoundments to include a second level of engineering review, (5) revised inspection 

procedures to require an annual inspection by a DSMRE engineer, and (6) notified each 

permittee with an MSHA-class impoundment that the MSHA-approved plan and the DSMREapproved permit must be the same. 

Actions by MSHA

MSHA administers the provisions of the Federal Mine Safety and Health Act of 1977 (Mine Act) 

to enforce compliance with mandatory miner safety and health standards. MSHA enforces the 

requirements of the Mine Act at all mining and mineral processing operations in the United 

States. Under the authority of the Mine Act, MSHA conducts accident investigations to 

determine cause(s) of mine accidents and to use and share this information with the mining 

community and others for the purpose of preventing similar occurrences. The accident 

investigations also include determinations of whether violations of the Mine Act or 

implementing regulations contributed to the accident. MSHA investigated the MCCC 

breakthrough and the inundation of the active underground mine and released its report of 

investigation on October 17, 2001. In its report, MSHA arrived at the following conclusions: 

“The failure of the Big Branch Refuse Impoundment and subsequent inundation 

of the 1-C Mine occurred because Martin County Coal Corporation failed to follow 

its approved Impoundment Sealing Plan, dated August 8, 1994, and subsequent 

modification, dated September 7, 1995. 

The plan, prepared by Ogden Environmental and Energy Services, Inc., specified a 

seepage barrier to be constructed along the perimeter of the impoundment where 

mining had occurred near the outcrop of the Coalburg seam. The stated objective 

of this seepage barrier was to limit the quantity of seepage passing from the 

impoundment into the underground mine of the 1-C Mine in the Coalburg seam. 

Additionally, the stated objective was limiting the release of impounded water 

and fine coal refuse from the impoundment should a breakthrough occur. 

The plan specifically states, “...following the completion of the ‘seepage barrier’ fine 

refuse shall be directed along the barrier by periodically redirecting the discharge of 

iii 
fine refuse slurry. As fine refuse settles and consolidates along the surface of the 

‘seepage barrier’, seepage should be further reduced due to the low permeability of 

consolidated fine refuse.” 

Redirecting of the discharge of the fine refuse slurry was not performed. Consequently, 

approximately 2 feet of water was present against the highly permeable shot sandstone 

portion of the seepage barrier at the location of the breakthrough. The absence of a fine 

refuse layer between the water and the shot sandstone in this area made the seepage 

barrier more permeable than intended. The seepage barrier failed to restrict flow through 

the barrier into the 1-C Mine, as the approved plan intended. 

The August 8, 1994, Impoundment Sealing Plan was developed without the benefit of 

additional geotechnical investigation of the overburden above the Coalburg coal seam in 

the area of the proposed seepage barrier. The actual thickness of the stratum above the 

coal seam and the thickness of the colluvial soil deposits were not determined. 

The plan, developed by the consultant and submitted by MCCC, was based on the 

assumption that the “seepage barrier” and strengthened mine seals would control the 

flow of any future breakthrough to the point where the active portion of the 1-C Mine 

would not be adversely affected. It was assumed that, if a breakthrough occurred, the 

discharge of water and slurry out of the South Mains Portal would not have a significant 

impact on the safety of miners. 

Martin County Coal Corporation’s failure to follow the approved plan resulted in internal 

erosion (“piping”) occurring at the location of the breakthrough. Over a period of time, 

the seepage into this area began to carry sand (weathered material) into the mine opening. 

As material was carried away, a “pipe” (void) formed and worked its way toward the 

impoundment. As more material was carried in the mine, a larger seepage path was 

created allowing more and larger particles to be carried away. This process continued 

until the void developed close enough to the impoundment that the remaining plug of 

material failed suddenly, allowing the contents of the impoundment to discharge 

uncontrolled into the mine.” 

Actions by DSMRE

Under the authority of the approved state program, DSMRE investigated the site after the 

breakthrough for compliance with the terms and conditions of Permit Number 680-8002, as well 

as the adjoining permits--Numbers 880-7000, 880-7002, and 680-5012. As a result of its 

investigation, on October 11, 2000, DSMRE issued Non-Compliance (NC) 41-1752, NC 41-

1753, NC 41-1754, NC 41-1800, and Imminent Danger Cessation Order (IDCO) 04-1241 to 

MCCC. Also, on February 13, 2001, DSMRE issued NC 41-1552 to MCCC. Following are 

details of these actions: 

IDCO 04-1241, Permit Number 680-8002. This IDCO relates to the conditions, as cited in NC 

41-1752, which created an imminent danger to the public and imminent harm to the 

environment. 

iv 
NC 41-1752, Permit Number 680-8002. Violations cited included: (1) failed to pass all drainage 

and slurry through approved sediment control structures prior to discharge into waters of the 

Commonwealth of Kentucky, (2) engaged in an unsafe practice by allowing substandard water 

and slurry to flow from an impoundment into the underground mine, creating imminent 

environmental damage off permit, in Wolf Creek and Coldwater Fork watersheds, and (3) failed 

to protect the hydrologic balance by allowing substandard water and slurry to enter waters of the 

Commonwealth of Kentucky. 

NC 41-1753, Permit Number 880-7000. Violations cited included: (1) allowed a large discharge 

to wash away sediment pond #200, and (2) allowed a large discharge to create a huge gully on 

the mine management area below sediment pond #200. 

NC 41-1754, Permit Number 880-7002. Violation cited included: Slurry and coal refuse from

the slurry discharge covered up three sediment holding areas (sumps). 

NC 41-1800, Permit Number 680-5012. Violation cited included: Sediment pond #326 is filled 

with slurry due to the slurry discharge. 

NC 41-1552, Permit Number 680-8002. Violations cited included: (1) failed to accurately 

depict the unmined barrier of coal in the Coalburg coal seam within the impoundment and (2) 

failed to comply with the terms and conditions of the approved permit including plans and 

documents provided as part of the approved permit including: a) exceeded the approved slurry 

elevation (pool) for Phase III of the Big Branch slurry impoundment, b) failed to construct 

hydraulic mine seal (bulkhead) at first left section, #2 North Main as approved by DSMRE, c) 

engaged in the unapproved backfilling of one of the South Mains portals, and d) failed to 

construct the seepage barrier according to approved designs. 

Actions by the National Research Council (Council)

Congress requested the Council to examine ways to reduce the potential for similar accidents in 

the future. To conduct this study, the Council appointed the Committee on Coal Waste 

Impoundments. The charge to the committee includes three major components. First, the 

committee was to examine engineering practices and standards currently being applied to coal 

waste impoundments and to consider options for evaluating, improving, and monitoring the 

barriers that retain coal waste impoundments. Second, the committee was charged with 

evaluating the accuracy of mine maps and exploring ways to improve surveying and mapping of 

underground mines to delineate more accurately how underground mines related to current or 

planned slurry impoundments. The third task was to evaluate alternative technologies that could 

reduce the amount of coal waste generated or allow productive use of the waste. The committee 

also examined alternative disposal options for coal slurry. The Council’s report was released on 

October 12, 2001. OSM is currently working with MSHA on a comprehensive response to the 

Council’s recommendations. The recommendations formulated in this report will be factored 

into OSM’s comprehensive response to the Council’s recommendations. 

v 
Conclusions and Recommendations 

OSM’s study of the breakthrough at the Big Branch slurry impoundment, conducted by a team of 

engineers, geologists, and hydrologists, was performed in cooperation with MSHA, DSMRE, 

and the Kentucky Department of Mines and Minerals. OSM used information and data relating 

to: 

 General history of the underground mine and impoundment. 

 DSMRE permit files and MSHA-approved plans. 

 

 Investigations of the 1994 breakthrough. 

 Remedial measures to prevent breakthroughs after 1994. 

 MCCC’s Emergency Action Plan (EAP). 

 MSHA’s investigation of the 2000 breakthrough. 

Based on its own independent technical evaluation, OSM is in agreement with the findings and 

enforcement actions taken to date by DSMRE and MSHA. The investigations by MSHA and 

DSMRE were primarily to determine if MCCC had violated the terms and conditions of the 

permit and plan approvals. MSHA also reported the probable breakthrough mechanism. The 

scope of OSM’s review included the same issues addressed by DSMRE and MSHA enforcement 

actions, as well as the probable breakthrough mechanism. In addition, OSM’s review included 

an evaluation of the sealing plan approval by DSMRE and certifications and actions taken to 

protect the public. OSM provided copies of this report in draft to DSMRE and MSHA to assure 

that jurisdiction, determinations, and actions by those agencies were properly described. OSM 

considered the comments from DSMRE and MSHA and made appropriate changes to clarify the 

jurisdiction, investigation, and determinations made by those agencies. OSM refined its 

technical analysis in response to the comments, but did not change appreciably its conclusions 

and recommendations. 

The following conclusions and recommendations are based upon OSM’s investigation of the 

factors contributing to the MCCC 2000 breakthrough. Although these conclusions are specific to 

this investigation, the recommendations are broadly applicable to the prevention of 

breakthroughs at other impoundments. OSM suggests that the recommendations be used in 

conjunction with the Criteria for Evaluating the Potential for Impoundment Leaks into 

Underground Mines (Existing and Proposed Impoundments) released by OSM in July 2001. The 

conclusions are grouped by the issues OSM agrees with MSHA and DSMRE to aid the reader to 

better understand the actions of the various agencies. 

vi 
Conclusions: 

In agreement with MSHA, 

 OSM concludes that the breakthrough was caused by seepage and piping through the 

outcrop barrier at the southwest corner of the 50-foot long, dead-end entry. 

 OSM concludes that MCCC failed to analyze and report a forewarning of the 

impending breakthrough--the significant increase of drainage from the South Mains 

Portal pond beginning in September 1999. 

 OSM concludes that MCCC did not submit an as-built certification for the 

constructed bulkheads. 

In agreement with DSMRE, 

 OSM concludes that MCCC submitted modifications to the 1994 Impoundment 

Sealing Plan to MSHA but not to DSMRE for approval. 

In agreement with both MSHA and DSMRE, 

 OSM concludes, after comparing the Triad drilling information with the 1994 

Impoundment Sealing Plan, that (a) the width of the Coalburg coal seam outcrop 

barrier (the horizontal distance from the underground mine to the surface) is correctly 

projected in the plan, but (b) the plan incorrectly indicates that the entire Coalburg 

coal seam outcrop barrier is composed of solid coal and rock.

 OSM concludes that MCCC did not conduct any geotechnical investigation to 

confirm the width or to determine the composition of the Coalburg coal seam

outcrop barrier either before or after the 1994 breakthrough.

 OSM concludes that MCCC did not construct the seepage barrier in accordance with 

the 1994 Impoundment Sealing Plan as approved by MSHA and DSMRE. 

Additional OSM Findings:

These issues may have been considered by DSMRE and MSHA, but were not addressed by their 

actions and reports.

 OSM cannot conclude definitively whether the 1994 Impoundment Sealing Plan 

would have prevented a breakthrough because the seepage barrier was not 

constructed in accordance with the plan. However, OSM found that the approved 

sealing plan did not contain a complete analysis of the breakthrough mechanisms and 

the associated preventative measures. 

vii 
 OSM concludes that MCCC did not submit an as-built stability analysis, for 

certification purposes, for the constructed seepage barrier. 

 OSM concludes that the 1994 Impoundment Sealing Plan (breakthrough prevention 

plan) was approved as a minor modification by DSMRE; and therefore, public notice 

was not required. 

 

 OSM concludes that the EAP submitted to MSHA addressed the consequences of an 

embankment failure, but did not address the consequences of an impoundment 

breakthrough. 

Recommendations: 

 OSM recommends that adequate geotechnical investigations be conducted to verify 

the location of the underground mine and the composition of the outcrop barrier and 

overburden for all existing and proposed impoundments in close proximity to either 

an active or abandoned underground mine. 

 OSM recommends that plans designed to prevent breakthroughs at slurry 

impoundments be based on the most conservative engineering design standards and 

be supported by the best site-specific, scientific data available, commensurate with 

the level of risk posed by the impoundment. 

 OSM recommends that the breakthrough prevention plans for any new impoundments 

or modifications to existing impoundments identify the critical phases of construction 

and that the registered professional engineer who designed the plan also inspect and 

certify the critical phases of construction with as-built drawings as appropriate. 

 OSM recommends that the breakthrough prevention plans include rigorous 

hydrogeologic monitoring requirements designed to provide a forewarning of any 

impending breakthrough. 

 OSM recommends that revisions to permits concerning breakthrough prevention be 

considered major modifications if the breakthroughs would adversely affect the 

public; and therefore, be subject to public notice and comment. 

 OSM recommends that the State Regulatory Authorities assess coordination 

procedures with MSHA for review and approval of impoundments to ensure proper 

fulfillment of respective statutory responsibilities. 

 Finally, OSM should consider developing national standards for EAPs, through 

rulemaking, which consider the consequences of an impoundment breakthrough.

viii 
BLANK PAGE 

ix 
TABLE OF CONTENTS 

 Page 

EXECUTIVE SUMMARY ..................................................................................................... ii 

1.0 INTRODUCTION.........................................................................................................1 

2.0 BACKGROUND .........................................................................................................15

2.1 Site Description ...............................................................................................15 

2.1.1 General setting

2.1.2 Underground mine

2.1.3 Outcrop barrier

2.1.4 Seepage barrier

2.1.5 Surface features around the impoundment

2.2 Site History ......................................................................................................19 

2.3 2000 Breakthrough Event ..............................................................................24 

2.4 Effects of the 2000 Breakthrough Event.......................................................25 

2.5 Responses by Federal and State Agencies ....................................................27 

3.0 THE IMPOUNDMENT BREAKTHROUGH INVESTIGATION........................29 

3.1 OSM Investigative Approach ........................................................................29 

3.2 1994 Breakthrough ........................................................................................30 

3.2.1 Description

3.2.2 Overburden conditions at the outcrop barrier

3.2.3 Analysis

x 
 Page 

3.3 Preventative Actions After the 1994 Breakthrough ....................................32 

3.3.1 Sealing plan

3.3.2 Technical and programmatic concerns

3.3.2.1 Seepage barrier permeability and slurry coating

3.3.2.2 Impoundment pool elevation

3.3.2.3 Seepage barrier stability

3.3.2.4 Plugging of future breakthroughs

3.3.2.5 Dimensions and stability of the outcrop barrier

3.3.2.6 Potential effects of blasting

3.3.2.7 Storage and control of breakthrough water in the

underground mine

3.3.2.8 DSMRE approval and implementation

3.3.2.9 Impoundment monitoring 

3.3.2.10 Employee awareness

3.4 MCCC EAP.....................................................................................................51 

3.5 2000 Breakthrough .........................................................................................51 

3.5.1 Subsurface investigation

3.5.1.1 Location of failure

3.5.1.2 Mine and surface map accuracy

3.5.1.3 Drill logs

3.5.1.4 Seepage barrier slurry coating and saturation

3.5.1.5 Enviroscan, Inc.’s Geophysical Survey

3.5.1.6 Borehole camera analysis

3.5.2 Mine Discharge Data 

3.5.3 Effects of Blasting

3.5.4 Effects of Natural Seismic Activity

3.5.5 Seepage Barrier Stability

3.5.6 Underground Mine Pillar Stability

4.0 PROBABLE BREAKTHROUGH MECHANISM..................................................69 

4.1 Failure of Sealed Underground Mine Openings..........................................69 

xi 
 Page 

4.2 Breakthrough at an Unsealed Underground Mine Opening ......................69 

4.3 Breakthrough at Coal Barriers......................................................................69 

4.3.1 Barrier size and composition 

4.3.2 Subsidence potential

4.3.3 Seepage barrier permeability 

4.3.4 Seepage and piping

4.3.5 Bridging and plugging

4.3.6 Other factors

4.4 Breakthrough at Strata Overlying the Coal Seam.......................................71 

5.0 CONCLUSIONS AND RECOMMENDATIONS....................................................73 

ACRONYMS...........................................................................................................................77 

BIBLIOGRAPHY...................................................................................................................79 

FIGURES 

Figure 1. Location Map .........................................................................................2

Figure 2. Mine Map................................................................................................4 

Figure 3. Cross-Section A-A’ at May 1994 Breakthrough ..................................17 

Figure 4. Cross-Section B-B’ of Seepage Barrier Constructed at 2000 

 Breakthrough ........................................................................................18

Figure 5. Cross-Section of Designed Seepage Barrier.........................................20 

Figure 6. Drill Hole Location Map.......................................................................53 

Figure 7. Triad Profile A-A..................................................................................55 

Figure 8. Triad Profile C-C ..................................................................................59 

Figure 9. Impoundment Elevation, South Mains Portal Pond Discharge, 

 and Precipitation ...................................................................................62 

PHOTOS 

Photo 1. Aerial Photograph of Big Branch Slurry Impoundment - 

 October 16, 2000 ....................................................................................3

Photo 2. 2000 Breakthrough Area - October 16, 2000..........................................5 

xii 
 Page

Photo 3. General View of Impoundment and Embankment - 

 October 16, 2000.....................................................................................6 

Photo 4. Number 2 North Portals - October 16, 2000...........................................7 

Photo 5. South Mains Portal - October 16, 2000 ..................................................8 

Photo 6. Seepage Barrier by 2000 Breakthrough (After Construction) - 

August 22, 1996....................................................................................21 

Photo 7. Surface Conditions at 1994 Breakthrough - June 1, 1989 ....................22 

Photo 8. Surface Conditions at 2000 Breakthrough - June 1, 1989 ....................23 

Photo 9. Construction of Seepage Barrier (Dozer Work) - 

March 6, 1995 .......................................................................................36 

Photo 10. Construction of Seepage Barrier (End Dumping by Rock 

Truck) - March 6, 1995.........................................................................37 

Photo 11. Construction of Seepage Barrier (Long View of Dozer and 

Truck) - March 6, 1995.........................................................................38 

Photo 12. Seepage Barrier by 2000 Breakthrough (During Construction) - 

April 24, 1995 .......................................................................................39 

Photo 13. Seepage Barrier by 2000 Breakthrough (During Construction) - 

June 8, 1995 ..........................................................................................40

Photo 14. Seepage Barrier by 2000 Breakthrough (After Construction) - 

June 26, 1995 ........................................................................................41 

APPENDICES 

Appendix 1. Office of Surface Mining Press Release and Action Plan and 

Appalachian Regional Coordinating Center Implementation Plan 

Appendix 2. Office of Surface Mining Report on Department for Surface 

Mining Reclamation and Enforcement Enforcement Actions 

Appendix 3. Office of Surface Mining Permit and Underground Mine Critique 

 and Chronology 

Appendix 4. Triad Project No. C00553 - Subsurface Investigation (for 

attachments, Refer to www.msha.gov)

Appendix 5. Enviroscan, Inc.’s Geophysical Survey 

Appendix 6. Office of Surface Mining Report on Seepage Barrier Stability 

Appendix 7. Office of Surface Mining Report on Certifications 

Appendix 8. Martin County Coal Corporation Emergency Action Plan 

Appendix 9. Mine Safety and Health Administration Information 

Bulletin No. P94-18, Emergency Action Plans

Appendix 10. Office of Surface Mining Report on South Mains Pond Portal 

 Discharge

Appendix 11. Office of Surface Mining Report on Blasting 

Appendix 12. Office of Surface Mining Report on Seismic Activity 

Appendix 13. Office of Surface Mining Report on Underground Mine Pillar 

 Stability 

xiii 
REPORT ON OCTOBER 2000 

BREAKTHROUGH AT THE BIG BRANCH SLURRY IMPOUNDMENT 

1.0 INTRODUCTION 

On October 11, 2000, a combination of coal slurry and water from the Martin County Coal 

Corporation (MCCC) Big Branch slurry impoundment in Martin County, Kentucky, broke 

through into an underground mine adjacent to the impoundment, consequently discharging into 

the receiving streams (Figure 1 [Page 2] and Photo 1 [Page 3]). The purpose of this study, 

performed by the Office of Surface Mining (OSM), U.S. Department of the Interior, was to 

evaluate the conditions and sequence of prior events primarily to determine the probable 

breakthrough mechanism. Also, OSM evaluated other factors, such as designs and approvals, 

which could have contributed to the 2000 breakthrough. To achieve this, OSM examined 

documentary evidence of MCCC’s activities in and near the impoundment over a period of 30 

years. 

MCCC operates the impoundment under Kentucky Department for Surface Mining Reclamation 

and Enforcement (DSMRE) Permit Number 680-8002 and Mine Safety and Health 

Administration (MSHA) identification number 1211-KY6-0035-01. MCCC operates the 

underground mine under DSMRE Permit Number 680-5012 and MSHA identification number 

15-03752. Coal processing waste from the MCCC Big Branch preparation plant is disposed of in 

the impoundment. 

An estimated 306 million gallons of water and fine coal refuse slurry (hereinafter referred to as 

slurry) drained from the MCCC impoundment into the adjacent underground mine (Figure 2 

[Page 4]; Photos 2 and 3 [Pages 5 and 6]). Approximately 245 million gallons of the water and 

slurry discharged from the underground mine at the Number 2 North Portals and the South 

Mains Portal (Photos 4 and 5 [Pages 7 and 8]). The remainder of the slurry was contained in the 

underground mine. The breakthrough into the underground mine was first noticed about 12:05 

a.m. and ended about 4:40 a.m. A detailed chronology of events surrounding the breakthrough is 

presented in Section 2.3. The discharge from the north portals entered Coldwater Fork, and the 

discharge from the south portals entered Wolf Creek. This was the second breakthrough event at 

this impoundment, the first having occurred in May 1994. 

The breakthrough in 2000 differed from the 1994 breakthrough in that the 2000 breakthrough 

resulted in severe stream degradation and property damage. The drop in pool level during the 

2000 event was significantly greater and occurred over a shorter time period than the 1994 event. 

MSHA has estimated that the discharge from the 1994 breakthrough was about one-third the 

discharge from the 2000 breakthrough (112 million gallons compared to 306 million gallons).

Whereas a large amount of the 1994 breakthrough water and slurry was retained in the mine, 

most of 2000 breakthrough slurry reached the surface. In the 1994 event, clear water comprised 

most of the surface discharge. During the 2000 breakthrough, slurry was a major component in 

the outflow. 

No personal injuries were reported as a direct result of the 2000 breakthrough. However, the 

slurry affected over 75 miles of streams in Kentucky and West Virginia causing considerable 

1 
Figure 1. Location Map. 

2 
Scale in Feet

10-16-2000

Photo 1. Aerial Photograph of Big Branch Slurry Impoundment - October 16, 2000. 

Source: Photo Science, Inc. A) Impoundment. B) 2000 breakthrough location. 

C) Number 2 North Mains Portals. D) South Mains Portal. E) Embankment (dam). 

F) Preparation plant. G) 1994 breakthrough location. 

3 
 

Figure 2. Mine Map.

4 
Photo 2. 2000 Breakthrough Area - October 16, 2000. Source: OSM. Pool elevation about 

1,060 feet msl prior to breakthrough and 1,046 feet msl after breakthrough. Mine roof 

elevation 973 feet msl. 

5 
Photo 3. General View of Impoundment and Embankment - October 16, 2000. 

Source: OSM. 2000 breakthrough area to left of photo, out of view. 

6 
Photo 4. Number 2 North Portals - October 16, 2000. Source: OSM. 

7 
Photo 5. South Mains Portal - October 16, 2000. Source: OSM. 

8 
aquatic impacts. At some locations, the slurry flooded over the banks and was deposited onto 

adjacent property. Six public water intakes were adversely affected and alternative water 

supplies had to be arranged. It was reported that the cost to clean up the waterways and affected 

lands exceeded 36 million dollars. 

The Surface Mining Control and Reclamation Act of 1977 (SMCRA) established OSM to 

oversee the enforcement of surface coal mining and reclamation operations. SMCRA provides 

that, if certain conditions are met, a state may assume primary authority for the regulation of the 

surface coal mining and reclamation operations within its borders. Kentucky obtained primary 

authority in 1982. The Kentucky program is administered by DSMRE. The federal 

requirements for the proper construction, maintenance, and reclamation of impoundments are in 

Section 515(b)(13) of SMCRA. The Kentucky requirements are in Section 350.425, Kentucky 

Revised Statutes, and Sections16:160 and 18:160, Title 405, Kentucky Administrative 

Regulations (KAR). Once a state has obtained primary authority, OSM has the responsibility to 

make the investigations, evaluations, and inspections necessary to determine whether the state 

program is being administered and enforced in accordance with the approved program

provisions. Under this unique partnership, OSM and DSMRE share responsibility for 

accomplishments as well as problems. Nonetheless, it is OSM’s role to investigate the MCCC 

breakthrough in accordance with its oversight responsibility and record appropriate observations 

and recommendations. 

As a result of several breakthroughs over the last few years, and the latest in Martin County, 

Kentucky, on November 2, 2000, OSM announced an action plan (Appendix 1) to assure that 

impoundment breakthroughs into the underground mine do not occur in the future. To 

accomplish the objectives spelled out in the OSM action plan, the Appalachian Regional 

Coordinating Center (ARCC) developed an implementation plan (also in Appendix 1) to 

complete the following three tasks: 

Task 1: Establish a regional impoundment technical committee to determine the factors 

contributing to the MCCC impoundment breakthrough. 

Task 2: Expand the technical committee to include state and MSHA technical representatives. 

The expanded committee, using its combined experience along with information gained from the 

Kentucky and Virginia experiences, will develop criteria that should be considered in 

reevaluating high-risk (high breakthrough potential) impoundments over or adjacent to 

underground mine workings. 

Task 3: Develop and implement individual field office work plans designed to minimize the 

potential for future impoundment leaks or breakthroughs into underground mine workings. 

This report is issued to complete Task 1. On July 27, 2001, ARCC issued Criteria for 

Evaluating the Potential for Impoundment Leaks into Underground Mines (Existing and 

Proposed Impoundments), to complete Task 2. The field offices in the Appalachian Region are 

in various stages of implementing Task 3. DSMRE, with assistance from OSM, is currently reevaluating all existing MSHA-class impoundments in Kentucky. As part of this initiative, 

DSMRE has taken the following actions: (1) implemented a plan for a joint OSM/DSMRE 

9 
permit review and field inspection of each of the 117 MSHA-class impoundments in Kentucky, 

(2) identified all structures within 500 feet of an underground mine, (3) completed a risk 

assessment for breakthrough potential on each impoundment including those rated as “high 

breakthrough potential” by MSHA, (4) revised existing protocols regarding review and approval 

of slurry impoundments to include a second level of engineering review, (5) revised inspection 

procedures to require an annual inspection by a DSMRE engineer, and (6) notified each 

permittee with an MSHA-class impoundment that the MSHA-approved plan and the DSMREapproved permit must be the same. 

MSHA administers the provisions of the Federal Mine Safety and Health Act of 1977 (Mine Act) 

to enforce compliance with mandatory miner safety and health standards. MSHA enforces the 

requirements of the Mine Act at all mining and mineral processing operations in the United 

States. Under the authority of the Mine Act, MSHA conducts accident investigations to 

determine cause(s) of mine accidents and to use and share this information with the mining 

community and others for the purpose of preventing similar occurrences. The accident 

investigations also include determinations of whether violations of the Mine Act or 

implementing regulations contributed to the accident. MSHA investigated the MCCC 

breakthrough and the inundation of the active underground mine and released its report of 

investigation on October 17, 2001. In its report, MSHA arrived at the following conclusions: 

“The failure of the Big Branch Refuse Impoundment and subsequent inundation 

of the 1-C Mine occurred because Martin County Coal Corporation failed to follow 

its approved Impoundment Sealing Plan, dated August 8, 1994, and subsequent 

modification, dated September 7, 1995. 

The plan, prepared by Ogden Environmental and Energy Services, Inc., specified a 

seepage barrier to be constructed along the perimeter of the impoundment where 

mining had occurred near the outcrop of the Coalburg seam. The stated objective 

of this seepage barrier was to limit the quantity of seepage passing from the 

impoundment into the underground mine of the 1-C Mine in the Coalburg seam. 

Additionally, the stated objective was limiting the release of impounded water 

and fine coal refuse from the impoundment should a breakthrough occur. 

The plan specifically states, “...following the completion of the ‘seepage barrier’ fine 

refuse shall be directed along the barrier by periodically redirecting the discharge of 

fine refuse slurry. As fine refuse settles and consolidates along the surface of the 

‘seepage barrier’, seepage should be further reduced due to the low permeability of

consolidated fine refuse.” 

Redirecting of the discharge of the fine refuse slurry was not performed. Consequently, 

approximately 2 feet of water was present against the highly permeable shot sandstone 

portion of the seepage barrier at the location of the breakthrough. The absence of a fine 

refuse layer between the water and the shot sandstone in this area made the seepage 

barrier more permeable than intended. The seepage barrier failed to restrict flow through 

the barrier into the 1-C Mine, as the approved plan intended. 

10 
The August 8, 1994, Impoundment Sealing Plan was developed without the benefit of 

additional geotechnical investigation of the overburden above the Coalburg coal seam in 

the area of the proposed seepage barrier. The actual thickness of the stratum above the 

coal seam and the thickness of the colluvial soil deposits were not determined. 

The plan, developed by the consultant and submitted by MCCC, was based on the 

assumption that the “seepage barrier” and strengthened mine seals would control the 

flow of any future breakthrough to the point where the active portion of the 1-C Mine 

would not be adversely affected. It was assumed that, if a breakthrough occurred, the 

discharge of water and slurry out of the South Mains Portal would not have a significant 

impact on the safety of miners. 

Martin County Coal Corporation’s failure to follow the approved plan resulted in internal 

erosion (“piping”) occurring at the location of the breakthrough. Over a period of time, 

the seepage into this area began to carry sand (weathered material) into the mine opening. 

As material was carried away, a “pipe” (void) formed and worked its way toward the 

impoundment. As more material was carried in the mine, a larger seepage path was 

created allowing more and larger particles to be carried away. This process continued 

until the void developed close enough to the impoundment that the remaining plug of 

material failed suddenly, allowing the contents of the impoundment to discharge 

uncontrolled into the mine.” 

The Kentucky Department of Mines and Minerals (DMM) administers the provisions of the 

Kentucky Underground Mining Law. The Kentucky law predates the federal Mine Act. Both 

Acts generally cover the same mining operations. DMM investigated the MCCC breakthrough

under the authority of the Kentucky law. 

MSHA, DMM, and DSMRE all took enforcement actions against MCCC concerning the 

breakthrough. MSHA and DMM each issued a “closure order” that restricts activities in the 

underground mine until safe conditions can be assured. On February 13, 2001, both MSHA and 

DSMRE ordered MCCC to submit a permitting action for the final closure and reclamation of 

the impoundment. Other state and federal agencies have taken separate enforcement actions. 

Under the authority of the approved state program, DSMRE investigated the site after the 

breakthrough for compliance with the terms and conditions of Permit Number 680-8002, as well 

as the adjoining permits--Numbers 880-7000, 880-7002, and 680-5012. As a result of its 

investigation, on October 11, 2000, DSMRE issued Non-Compliance (NC) 41-1752, NC 41-

1753, NC 41-1754, NC 41-1800, and Imminent Danger Cessation Order (IDCO) 04-1241 to 

MCCC. Also, on February 13, 2001, DSMRE issued NC 41-1552 to MCCC. DSMRE’s 

enforcement actions are described in Appendix 2. Following are details of these actions: 

IDCO 04-1241, Permit Number 680-8002. This IDCO relates to the conditions, as cited in NC 

41-1752, which created an imminent danger to the public and imminent harm to the 

environment. 

11 
NC 41-1752, Permit Number 680-8002. Violations cited included: (1) failed to pass all drainage 

and slurry through approved sediment control structures prior to discharge into waters of the 

Commonwealth of Kentucky, (2) engaged in an unsafe practice by allowing substandard water 

and slurry to flow from an impoundment into the underground mine, creating imminent 

environmental damage off permit, in Wolf Creek and Coldwater Fork watersheds, and (3) failed 

to protect the hydrologic balance by allowing substandard water and slurry to enter waters of the 

Commonwealth of Kentucky. 

NC 41-1753, Permit Number 880-7000. Violations cited included: (1) allowed a large discharge 

to wash away sediment pond #200, and (2) allowed a large discharge to create a huge gully on 

the mine management area below sediment pond #200. 

NC 41-1754, Permit Number 880-7002. Violation cited included: Slurry and coal refuse from

the slurry discharge covered up three sediment-holding areas (sumps). 

NC 41-1800, Permit Number 680-5012. Violation cited included: Sediment pond #326 is filled 

with slurry due to the slurry discharge. 

NC 41-1552, Permit Number 680-8002. Violations cited included: (1) failed to accurately 

depict the unmined barrier of coal in the Coalburg coal seam within the impoundment, and (2) 

failed to comply with the terms and conditions of the approved permit including plans and 

documents provided as part of the approved permit including: (a) exceeded the approved slurry 

elevation (pool) for Phase III of the Big Branch slurry impoundment, (b) failed to construct 

hydraulic mine seal (bulkhead) at first left section, #2 North Main as approved by DSMRE, (c) 

engaged in the unapproved backfilling of one of the South Mains portals, and (d) failed to 

construct the seepage barrier according to approved designs. 

In addition, Congress requested the National Research Council to examine ways to reduce the 

potential for similar accidents in the future. To conduct this study, the National Research 

Council (Council) appointed the Committee on Coal Waste Impoundments. The charge to the 

committee includes three major components. First, the committee was to examine engineering 

practices and standards currently being applied to coal waste impoundments and to consider 

options for evaluating, improving, and monitoring the barriers that retain coal waste 

impoundments. Second, the committee was charged with evaluating the accuracy of mine maps 

and exploring ways to improve surveying and mapping of underground mines to delineate more 

accurately how underground mines related to current or planned slurry impoundments. The third 

task was to evaluate alternative technologies that could reduce the amount of coal waste 

generated or allow productive use of the waste. The committee also examined alternative 

disposal options for coal slurry. The Council’s report was released on October 12, 2001. OSM 

is currently working with MSHA on a comprehensive response to the Council’s 

recommendations. The recommendations formulated in this report will be factored into OSM’s 

comprehensive response to the Council’s recommendations. 

OSM’s study of the breakthrough at the Big Branch slurry impoundment, conducted by a team of 

engineers, geologists, and hydrologists, was performed in cooperation with MSHA, DSMRE, 

and DMM. OSM used information and data relating to: 

12 
 General history of the underground mine and impoundment. 

 DSMRE permit files and MSHA-approved plans. 

 Investigations of the 1994 breakthrough. 

 Remedial measures to prevent breakthroughs after 1994. 

 MCCC’s Emergency Action Plan (EAP). 

 MSHA’s investigation of the 2000 breakthrough. 

The investigations by MSHA and DSMRE were primarily to determine if MCCC had violated 

the terms and conditions of the permit and plan approvals. MSHA also reported the probable 

breakthrough mechanism. The scope of OSM’s review included the same issues addressed by 

DSMRE and MSHA enforcement actions, as well as the probable breakthrough mechanism. In 

addition, OSM’s review included an evaluation of the sealing plan approval and certification and 

actions taken to protect the public. OSM provided copies of this report in draft to DSMRE and 

MSHA to assure that jurisdiction, determinations, and actions by those agencies were properly 

described. OSM considered the comments from DSMRE and MSHA and made appropriate 

changes to clarify the jurisdiction, investigation, and determinations made by those agencies. 

OSM refined its technical analysis in response to the comments, but did not change appreciably 

its conclusions and recommendations. 

13 
BLANK PAGE

14 
2.0 BACKGROUND 

 2.1 Site Description

2.1.1 General setting: The study site is located near Inez (Martin County), Kentucky. The 

approximate coordinates are N 37° 44’ 30” latitude and W 82° 32’ 18” longitude. The pertinent 

rock units comprise the Breathitt Group of the Princess Formation and include the Coalburg and 

Stockton coal seams, which were mined in the area. The Coalburg coal seam dips locally to the 

south at the minesite near the impoundment. 

The subject impoundment lies in Big Branch, a south-southeast flowing, tributary of Wolf Creek. 

The impoundment covers an area of 68 acres, with a shoreline of about 9,400 feet (Figure 2 

[Page 4]). A coarse coal refuse embankment serves as a dam to the impounded slurry. The crest 

of the embankment is approximately 256 feet above the downstream toe. The embankment 

currently has a surface elevation of 1,096 feet mean sea level (msl) and was designed to reach an 

elevation of 1,200 feet msl. The slurry level behind the embankment was at 1,060 feet msl

1

before the breakthrough and is presently at 1,046 feet msl. The impoundment has a 333-acre 

watershed. The watershed includes the pool area and embankment as well as the areas that drain 

toward the pool and embankment. At the time of the 2000 breakthrough, only about 90 of the 

333 acres drained into the impoundment. Both the slurry in the impoundment and the coarse 

refuse in the embankment are by-products of the coal preparation facility associated with 

cleaning coal from underground and surface mining in the Coalburg and other coal seams. 

2.1.2 Underground mine: The impoundment is bounded by the MCCC 1-C underground mine 

on all sides except the valley of Big Branch south-southeast of the embankment (Figure 2 [Page 

4]). The mine consists of the active North Mains and inactive room-and-pillar extraction areas. 

The mine areas adjacent to the North Mains have been sealed. No pillar recovery was conducted 

in the underground mine adjacent to the impoundment. The underground mine flanks the 

impoundment to the north, east, and west. The North Mains contain a conveyer system that 

carried coal from adjacent mines to the preparation plant south of the embankment until the 2000 

breakthrough. Two extraction areas, mined during 1981 and 1982, abut the impoundment to the 

north and south, and at some points, extend short distances underneath the impoundment. Both 

the 1994 and 2000 breakthroughs occurred over the extraction areas of the mine. Additional 

features of the underground mine pertinent to the study include: 

 Ventilation seals constructed in 1981 at the entrance to Area #2. (These seals required 

repair in 1984 or 1985, having been damaged by slurry injected into the mine for disposal 

purposes.) 

 The Mill Branch Portals south of the impoundment where water discharged after the 

1994 breakthrough. 

 The South Mains Portal and Number 2 North Portals west and north of the impoundment, 

respectively, from which slurry discharged during the 2000 breakthrough. 

 1

 As discussed in Appendix 3, MCCC had exceeded the slurry (pool) elevation approved by DSMRE for 

Phase III of the Big Branch slurry impoundment.

15 
 Reinforced concrete bulkheads off of the North Mains, constructed in 1996 as part of the 

approved impoundment sealing plan2

 to prevent breakthrough water from flooding the 

conveyor system (the bulkheads were built against existing ventilation seals constructed 

in 1987). 

The sealing plan map shows three areas where slurry was injected into the underground mine. 

This was apparently conducted prior to 1985. This investigation did not find any other 

documentation concerning the location, timing, and quantity of slurry injected into the 

underground mine. 

2.1.3 Outcrop barrier: The outcrop barrier, the material between the underground mine void 

and the ground surface, is composed of both weathered and solid rock and in-place coal seam. 

Within the impoundment area, the horizontal thickness of the underground mine outcrop barrier, 

as shown on the mine maps, ranges from about 35 feet to more than 300 feet. Vertical 

overburden thickness at the edge of the mine ranges from about 13 feet to greater than 100 feet. 

OSM’s estimates of the barrier are based on the coal cropline drawn on the map attached to the 

sealing plan. The coal cropline appears to be based on the horizontal projection of the mine floor 

or coal seam to the surface. MCCC did not conduct a geotechnical investigation to confirm the 

outcrop barrier width or its composition. The map indicated that the outcrop barrier is about 60 

feet wide at the 1994 breakthrough and about 70 feet wide at the 2000 breakthrough (Figures 3 

and 4 [Pages 17 and 18]). At the west side of the impoundment, one mine entryway “punched 

through” the outcrop to the ground surface. The permit does not address the punchout. The 

narrowest barrier is at the entry adjacent to the punchout. Reportedly, the punchout was sealed 

with concrete, but OSM could not find written documentation of the closure. Presently, the 

seepage barrier covers both areas. 

Interviews conducted by MSHA with miners who worked in the underground mine indicated 

that: 

 The mining height exceeded ten feet in some areas. 

 The underground mine was extended towards the coal outcrop until poor roof conditions 

or poor coal quality were encountered. As a general practice, mining projections (i.e., the 

delineation of areas to be mined and drawn on the mine maps) extend to the 50-foot 

overburden cover line. Actual mined-out area varies from these projections based on 

localized conditions. 

 The mine roof was generally composed of massive sandstone, which could be unstable 

from weathering and fractures near the outcrop. Natural vertical to near vertical fractures 

with one to two inches of separation were present in the mine increasing with greater 

frequency near the outcrop. 

 

 2 As a result of the 1994 breakthrough, MCCC prepared the sealing plan referenced in this report. This 

plan was approved by MSHA on October 20, 1994. MCCC also submitted the plan to DSMRE as part of minor 

permit revision number 5. The permit revision was approved December 7, 1994. This report refers to the MSHA 

and DSMRE approved plan and revision collectively as the “sealing plan.” 

16 
Figure 3. Cross-Section A-A’ at May 1994 Breakthrough. Drawn by OSM. 

17 
Figure 4. Cross-Section B-B’ of Seepage Barrier Constructed at 2000 Breakthrough. Drawn by OSM with 

Triad Profile D-D inserted. 

18 
Roof fall notations in the North Mains on DMM mine maps may be indicative of poor roof 

conditions that could occur adjacent to the outcrop barrier. 

2.1.4 Seepage barrier: As a result of the 1994 breakthrough, MCCC developed the sealing plan 

to “reduce the potential of a breakthrough and limit the rapid release of impounded water in the 

mine.” The approved seepage barrier proposed covering a portion of the outcrop barrier with 12 

to 25 feet of spoil material (Figure 5 [Page 20]). Upon approval of the sealing plan, MCCC 

constructed the seepage barrier (Photo 6 [Page 21]) by blasting a contour bench while mining the 

Stockton coal seam. Blasted material (spoil material) was pushed downslope to cover the 

Coalburg coal seam outcrop barrier. Consequently, the seepage barrier is composed primarily of 

sand, small sandstone fragments, and sandstone boulders. 

The seepage barrier was constructed around the north, west, and southwest sides of the 

impoundment. MCCC did not extend the barrier to the eastern side, where the Coalburg coal 

seam outcrop barrier is in excess of 300 feet wide. The construction of the seepage barrier 

resulted in a contour bench at about 1,075 feet msl. West of the embankment, the seepage 

barrier has been covered with coarse refuse. 

2.1.5 Surface features around the impoundment: At various times, clearing and grubbing, 

construction of roads and drainage ditches, and other activities have been performed around the 

impoundment. The size and stability of an outcrop barrier can be affected by cut and/or fill 

activities on the surface. OSM noted evidence of such surface modifications at the locations of 

the 1994 and 2000 breakthroughs. According to a map attached to the sealing plan, there was a 

road or diversion ditch about 20 feet below the Coalburg coal seam cropline near the 1994 

breakthrough (Figure 3 [Page 17]). The map is based on 1985 aerial photography. It is not clear 

whether the road was excavated into the hillside or constructed on fill material obtained from

clearing and grubbing operations. A June 1, 1989, aerial video shows another road a few feet 

above the top of the projected Coalburg coal seam and a road higher up the hillside (Figure 3 and 

Photo 7 [Pages 17 and 22]). These roads appear to have been excavated into the hillside. 

 

The map also shows either a road or a diversion ditch about 13 feet below the Coalburg coal 

seam cropline near the 2000 breakthrough point. A June 1, 1989, aerial video shows another 

road approximately ten feet above the coal seam (Figure 4 and Photo 8 [Pages 18 and 23]). The 

permit maps and aerial photographs do not provide sufficient clarity to allow a determination 

whether this road was excavated into the hillside or constructed on fill material. 

2.2 Site History

A detailed chronology of the impoundment and underground mine is provided in Appendix 3. A 

brief chronology of mining-related events at the study site up to the 2000 breakthrough event is 

presented below. 

MCCC opened the underground mine in the Coalburg coal seam in October 1971. The roomand-pillar mining commenced at the North Mains Portals located near the preparation plant. The 

North and South Mains had been established by mid-1973 and late 1979, respectively. Mine 

Area #1, adjacent to the 1994 breakthrough, was mined in 1981 and 1982. Mine Area #2, 

19 
Figure 5. Cross-Section of Designed Seepage Barrier. Source: Sealing Plan, Details Sheet. Information 

added by OSM: 1) Mine roof caving height based on five times the mining height--line A for 12-foot mining height, line B for 10-foot mining height, line C for 7.5-foot mining height, and line D for 6-foot mining height; 2) Outcrop barrier width—vertical line E for 70-foot width, vertical line F for 50-foot width, and vertical line G for 35-foot width; 3) Lateral extent of subsidence based on a 45-degree angle of draw per MCCC —slanted line H based on a 70-foot wide outcrop barrier, slanted line I based on a 50-foot wide outcrop barrier, and slanted line J based on a 35-foot wide outcrop barrier. 

20 
Photo 6. Seepage Barrier by 2000 Breakthrough (After Construction) - August 22, 1996. 

Source: DSMRE aerial video. The X marks the approximate location of the 2000 

breakthrough. Pool elevation 1,018 feet msl. Mine roof elevation 973 feet msl. Contour 

bench elevation 1,075 feet msl. 

 

21 
Photo 7. Surface Conditions at 1994 Breakthrough - June 1, 1989. Source: DSMRE aerial 

video. The X marks the approximate location of the 1994 breakthrough. Pool elevation 

958 feet msl. Mine roof elevation 964 feet msl. 

22 
Photo 8. Surface Conditions at 2000 Breakthrough – June 1, 1989. Source: DSMRE aerial 

video. Pool elevation 958 feet msl. Mine roof elevation 973 feet msl. 

23 
adjacent to the 2000 breakthrough, was mined in 1981. No known pillar extraction was 

conducted in these mining areas. 

 

On August 26, 1984, DSMRE approved Permit Number 680-8002 as a permanent program

permit under the approved state program. This permitting action brought the Big Branch site 

under all performance standards of SMCRA. A permit amendment for the construction of the 

coal slurry impoundment was approved by DSMRE on July 30, 1986. Construction of the 

impoundment commenced shortly afterwards. The impoundment pool elevation reached the 

level of the Coalburg coal seam in 1989. 

On May 22, 1994, as the pool level reached 28 feet above the Coalburg coal seam, a major 

breakthrough into the underground mine occurred at the southwest side of the impoundment 

(Figures 2 and 3 [Pages 4 and 17] and Photo 1 [Page 3]). An unusual amount of water from the 

underground mine was observed in Big Branch at about 11:30 p.m. The exact location of the 

impoundment breakthrough was not discovered until about 2:55 a.m. on May 23, 1994. 

Emergency repairs were started at 3:30 a.m., and the flow was stopped at 6:30 a.m. 

On August 8, 1994, MCCC submitted the sealing plan to MSHA. The purpose of the sealing 

plan, which was developed by Ogden Environmental and Energy Services (Ogden), was to 

reduce the potential for future breakthroughs. On August 18, 1994, Summit Engineering, Inc, 

(Summit), on behalf of MCCC, submitted Minor Permit Revision No. 5 (the permit revision) to 

DSMRE. The permit revision included the sealing plan as well as additional information 

required by the DSMRE permitting process. The sealing plan covered the seepage barrier, 

bulkheads adjacent to the North Mains, wet seals at the South Mains Portal, and monitoring of 

the drainage from the South Mains Portal. MSHA approved the sealing plan on October 20, 

1994, and DSMRE approved the permit revision on December 7, 1994. 

MCCC commenced construction of the seepage barrier in February 1995. Based on photos taken 

by Ogden during weekly inspections3

, construction of the barrier appears to have reached the 

location of the 2000 breakthrough in late March to early April 1995. The July 1996 annual 

certification reported that the seepage barrier was completed around September 1995. 

2.3 2000 Breakthrough Event 

A detailed recounting of observations and actions pertaining to the 2000 breakthrough are 

presented below. 

At 7:00 p.m. on October 10, 2000, a dozer operator observed that the face of the coarse refuse fill 

sank about eight to ten feet into the pool. This coarse refuse disposal area is located at the 

southwest end of the impoundment, across the pool from the impending breakthrough and is not 

part of the impoundment embankment. OSM could not correlate this condition with the 

breakthrough. 

 3

 Weekly inspections by the mining company are required by the MSHA regulations. Ogden, and later 

Geo/Environmental Associates, Inc. (GAI), conducted the weekly inspections for MCCC. 

24 
At about 11:45 p.m., the conveyor belt examiner inspected the bulkheads off the North Mains of 

the underground mine (Figure 2 [Page 4]). He did not identify any drainage through the 

bulkheads. The conveyor belt examiner left the underground mine shortly after 11:45 p.m. 

However, twenty minutes later, at about 12:05 a.m. on October 11, 2000, MCCC’s underground 

coal conveyor beltline monitor indicated that the Number 2 beltline in the North Mains had shut 

down. The dispatcher called the beltline electrician and instructed him to investigate the cause of

the shutdown. Around 12:10 a.m., the electrician notified the dispatcher that “gray stuff,” about 

two to three feet deep, was exiting the Number 2 North Portals. A short time later, MCCC 

personnel also observed a high discharge of water and slurry coming out of the South Mains 

Portal. The general mine foreman was notified of the situation at about 12.15 a.m.

About 12:20 a.m., the return water pump, used to recycle water from the impoundment for use in 

the preparation plant, stopped operating. Around the same time, the belt examiner radioed the 

dispatcher to report slurry three to four feet deep at the Number 2 North Portals. The preparation 

plant supervisor heard this call to the dispatcher and, at approximately 12:30 a.m., went to 

inspect the impoundment. The dispatcher notified the MCCC president of the problem at 12:30 

a.m., and the president notified the plant superintendent, chief of security, and safety manager. 

The preparation plant supervisor arrived at the impoundment at about 12:35 a.m., and observed 

that the pool level had dropped approximately three feet. At 1:00 a.m., the preparation plant 

supervisor located the breakthrough and observed water in the impoundment converging at the 

breakthrough location (Figure 2 [Page 4]). By then, the water level had dropped an additional 

three to five feet. MCCC security personnel established a roadblock on the country road along 

Wolf Creek sometime close to 1:15 a.m. Flow increases were observed in both Coldwater Fork 

(downstream of the Number 2 North Portals) and Wolf Creek (downstream of the South Mains 

Portal) by around 1:40 a.m.

 

At about 2:20 a.m., the preparation plant supervisor notified the impoundment coarse refuse 

dozer operator of the breakthrough and instructed him to take his dozer to the site. The dozer 

operator arrived at the site at approximately 2:40 a.m. and began pushing spoil into the 

breakthrough. Additional dozers subsequently arrived at the site to assist. MCCC notified 

MSHA, Kentucky’s Disaster and Emergency Services (DES), and Department of Fish and 

Wildlife Resources of the breakthrough around 3:00 a.m. MCCC notified DMM approximately 

20 minutes later. MCCC discussed the need for site evacuation with DES and the Martin County 

Sheriff’s Office. 

By 4:42 a.m., MCCC observed that flow through the breakthrough area had stopped. The pool 

elevation of the 68-acre impoundment had dropped approximately 14 feet. An estimated 306 

million gallons of slurry had drained from the impoundment. MCCC called the Prestonsburg 

DSMRE office before 7:30 a.m. and left a message on the answering machine that they had a 

“black water” discharge. MCCC made a follow-up call later that morning. 

2.4 Effects of the 2000 Breakthrough Event 

The slurry discharge from the Number 2 North Portals immediately filled and overtopped a 

sediment control pond. As the discharge moved downstream along the upper reaches of 

25 
Coldwater Fork, slurry filled and overtopped the stream channel for the first eight miles, 

covering the narrow valley flood plain and property of some of the residents. Seven homes 

became inaccessible. Coldwater Fork empties into Rockcastle Creek, which runs through Inez, 

Kentucky. While the spill remained largely within the stream channel, it continued to discolor 

the stream beyond Inez. 

The South Mains Portal discharge eroded a very large gully a short distance from the portal and 

destroyed a sediment control pond. The slurry then entered Big Andy Branch and Panther Fork 

before entering Wolf Creek. Wolf Creek drains into the Tug Fork of the Big Sandy River. 

Overtopping of the stream banks occurred in the first four miles of the Wolf Creek drainage. 

The movement of the slurry down Wolf Creek, Tug Fork, and the Big Sandy River caused 

significant problems with the downstream water supplies. As a result, on October 16, 2000, 

Kentucky Governor Paul Patton declared a state of emergency in ten counties in northeast 

Kentucky. The ten counties included Martin, Lawrence, Boyd, Carter, Greenup, Lewis, Fleming, 

Mason, Robertson, and Bracken. Within one week of the breakthrough, over 75 miles of stream

below the impoundment had been impacted. By October 17, 2000, the spill reached the Ohio 

River at Catlettsburg, Kentucky. 

The visibility of the slurry diminished as it flowed down stream. By the time the slurry reached 

the Ohio River, most of the coal refuse had settled out of suspension. The slurry impacted 

municipal water supplies at: 

 Kermit, West Virginia, located on the Tug Fork just below the mouth of Wolf Creek. 

 Crum, West Virginia, located downstream of Kermit on the Tug Fork with municipal 

water supplied by Kermit. 

 Louisa, Kentucky, which withdraws water from the Levisa Fork of the Big Sandy River. 

 Fort Gay, West Virginia, which withdraws water from the Tug Fork at the Big Sandy 

River confluence located across the river from Louisa. 

 Kenova, West Virginia, which withdraws water from the Big Sandy River. 

 Inez, Kentucky, located on Rockcastle Creek. 

No comprehensive listing of impacts was prepared as part of this study. Media reports indicated 

that Lawrence County and Martin County public schools were closed after the breakthrough due 

to the municipal water supply impacts. Also, American Electric Power, which uses water from

the Big Sandy River, shut down its power plant due to the spill.

Only minor impacts to the embankment occurred as a result of the breakthrough. Minor 

sloughing occurred on the upstream side of the embankment, presumably as a result of the 

sudden drawdown of the pool during the breakthrough. 

26 
Massey Energy Company, the MCCC’s parent company, in its May 29, 2001, second quarter 

corporate news report for fiscal year 2001, discussed the clean-up effort. The report stated that 

“over 500 people and 300 pieces of equipment were mobilized to clean up the Martin County 

Coal slurry spill, which has now been completed. Total cost for the clean up is now estimated at 

$56 million dollars, with all but approximately $3 million expected to be covered by insurance.” 

On September 14, 2001, Massey Energy Company reported that 36.9 million dollars had been 

spent on the clean-up effort through July 31, 2001. A number of civil suits are pending, 

involving numerous citizens of the area alleging impacts and seeking damages from MCCC. 

 

2.5 Responses by Federal and State Agencies 

The release of waste materials into the waters of the United States without a permit violates the 

Clean Water Act. Region 4 of the United States Environmental Protection Agency (EPA) was 

contacted by the National Response Center (NRC)4

 and responded immediately to the release 

along with the Commonwealth of Kentucky. An On Scene Coordinator (OSC) from EPA was 

dispatched to the site immediately. As required by the National Oil and Hazardous Substances 

Pollution Contingency Plan5

, the EPA OSC established the Unified Command/Incident 

Command to coordinate the response. All agencies with regulatory jurisdiction agreed to 

participate in a Unified Incident Command Organization (Unified Command). The Unified 

Command was charged with assisting in the coordination of clean-up efforts and ensuring the 

safety of the public and clean-up workers. Within the Unified Command, the Environmental 

Unit was established to address environmental issues. The Stream Bank Assessment and 

Cleanup Survey Team was formed as an integral part of the Environmental Unit to address 

specific removal needs of individual stream segments. This team consisted of representatives of 

EPA, Kentucky, West Virginia, and MCCC. All actions relative to the cleanup were reviewed 

and approved by each of the representatives. 

During this time, DSMRE monitored site conditions and reviewed MCCC’s plans for the 

removal and storage of the slurry spill. DSMRE’s approval was required prior to 

implementation of the remedial plans. DSMRE also assisted the MSHA investigation by 

conducting down-hole videotaping of the drill holes, attended the MSHA interviews, and 

conducted its own investigation of the breakthrough. OSM also monitored the cleanup and 

provided assistance and support to DSMRE. 

The MSHA investigation began shortly after the 2000 breakthrough. MSHA interviewed a total 

of 44 people, including past and present MCCC employees, contractors and consultants to 

MCCC, and property owners adjacent to the affected streams. The interviews began December 

4

 The NRC is the federal government’s national communications center, which is staffed 24 hours a day by

U.S. Coast Guard officers and marine science technicians. The NRC receives all reports of releases involving 

hazardous substances and oil that trigger the federal notification requirements under several laws. Reports to the 

NRC activate the National Contingency Plan and the federal government’s response capabilities. 

5

 The National Oil and Hazardous Substances Pollution Contingency Plan, more commonly called the 

National Contingency Plan (NCP), is the federal government’s blueprint for responding to both oil spills and 

hazardous substance releases. The NCP, promulgated pursuant to 42 U.S.C. Section 9605, codified at 40 CFR Part 

300, is the result of the government’s efforts to develop a national response capability and promote overall 

coordination among the hierarchy of responders and contingency plans. 

27 
5, 2000, and were completed February 1, 2001. MSHA also contracted with Triad Engineering,

Inc. (Triad) to conduct a subsurface investigation of the seepage and outcrop barriers (Appendix 

4). This involved drilling and core logging of 47 holes at the 2000 breakthrough location and the 

performance of electrical conductivity surveys (Appendix 5) at various points along the barriers. 

The field work was completed on January 23, 2001. 

 

28 
3.0 THE IMPOUNDMENT BREAKTHROUGH INVESTIGATION 

3.1 OSM Investigative Approach 

The OSM investigation of the 1994 and 2000 breakthrough events encompassed the following 

tasks: 

1. Review of information obtained from the MSHA interviews. 

2. Review of the impoundment permit files and MCCC 1-C underground mine map 

files, including: 

 Underground mine maps. 

 The sealing plan. 

 MSHA and DSMRE review letters relating to the sealing plan. 

 MCCC response letters. 

 Certifications. 

 Blasting plan and records. 

3. Analysis of photographs, including: 

 Aerial photographs obtained from the Kentucky Department of 

Transportation, GRW Aerial Surveys, Inc., and Photo Science, Inc. 

 Aerial video taken by DSMRE. 

 Weekly inspection photographs taken by Ogden during the construction of the 

seepage barrier. 

4. Analysis of data obtained from: 

 Triad drilling. 

 DSMRE borehole video. 

 Enviroscan geophysical survey. 

 National Weather Service precipitation records. 

 Kentucky Geological Survey (KGS) earthquake seismic records. 

 MCCC mine-portal discharges. 

 MCCC impoundment-pool levels prior to and during the 2000 breakthrough. 

5. OSM modeling, including: 

 Seepage barrier stability. 

 Underground mine pillar stability. 

 Blasting vibration levels. 

 Geologic modeling using Earthvision. 

 Precipitation and pond discharge trends. 

29 
In completing these tasks, OSM evaluated the conditions and sequence of prior events and 

determined the probable breakthrough mechanism for the 2000 breakthrough. In arriving at this 

determination, OSM evaluated other factors, such as designs and approvals, which could have

contributed to the 2000 breakthrough. In OSM’s report entitled Criteria for Evaluating the 

Potential for Impoundment Leaks into Underground Mines (Existing and Proposed 

Impoundments), Section E discusses “Failure Mechanisms.” In this section, OSM states the 

following: 

“Potential failure mechanisms include but are not limited to: 

1. Failure of sealed underground mine openings: The opening seal (rock/soil or 

other material) fails, thus allowing water/slurry to flow in an uncontrolled manner 

into the underground mine. Underground mine openings include, but are not 

limited to “punchouts,” (i.e., an intentional or unintentional void or tunnel-like 

connection of the underground mine to the surface), portals, horizontal drainage 

and ventilation borings, vertical utility or ventilation borings, adits [another term

for a type of underground mine entry] and underground mines, and auger holes 

that connect with underground mines. 

2. Breakthrough at an unsealed underground mine opening: Water/slurry flow into a 

mine opening that has not been sealed. These openings may have only been 

covered with soil. 

3. Breakthrough at coal barriers (e.g., outcrop barriers; barriers between contour and 

underground mines; barriers between auger holes and underground mines; 

barriers between small drift mines or house coal adits): Pressures resulting from

deposition of water/slurry/other materials may cause a failure at the coal barrier 

and allow water/slurry to enter the mine in an uncontrolled manner. 

4. Breakthrough at strata overlying the coal seam: Water/slurry flow into a mine 

through natural fractures and joints and mining-induced fractures (e.g., roof falls, 

sinkhole subsidence, and trough subsidence).” 

Throughout this study, OSM considered each of these potential failure (breakthrough) 

mechanisms. 

3.2 1994 Breakthrough

3.2.1 Description: The breakthrough occurred on May 22, 1994, at the end of a 45-foot long, 

20-foot wide dead-end entry in the underground mine in the Coalburg coal seam. The released 

material, primarily water, resulted in a blowout in the barrier between the underground mine and 

a contour mine cut near the Big Branch preparation plant. The event also caused a blowout of 

the South Mains Portal’s seals. Impoundment water discharged into Wolf Creek (through the 

South Mains Portal); Mill Branch (through the Mill Branch Portals); and Big Branch (through 

the barrier blowout). At the time of the breakthrough, the pool was at 992 feet msl and about 28 

feet above the roof of the mine (Figure 3 [Page 17]). The pool level then dropped by about 6 

30 
feet. In the October 17, 2001, report of investigation, MSHA estimated that 112 million gallons 

of water and slurry drained into the underground mine during the 1994 breakthrough. An 

unknown amount of water discharged from the underground mine to the surface drainage system. 

According to the sealing plan: 

 There was a “funnel shape” opening at the point of the breakthrough. 

 Inspection of the breakthrough point after the event revealed that a sinkhole had formed 

in the partially consolidated slurry with side slopes less than 45 degrees. 

 The breakthrough may have been the result of subsidence caused by a roof fall in the 

mine. 

 During the breakthrough, the majority of the clear water in the impoundment, but only a 

small amount of slurry, drained into the underground mine. 

3.2.2 Overburden conditions at the outcrop barrier: In order to determine the depth and 

lithology of the overburden materials at the 1994 breakthrough location, OSM examined 

information obtained after both the 1994 and 2000 breakthroughs. This included the sealing 

plan, the MSHA interviews, and the Triad drilling data. Some inferences were drawn from the 

Triad drilling near the 2000 breakthrough. 

The sealing plan map shows about 60 feet horizontal distance between the 1994 breakthrough 

entry and the Coalburg coal seam cropline (Figure 3 [Page 17]). The position of the cropline was 

projected to the land surface from the elevation of the mine floor. The mining height at the 

breakthrough was 93 inches (7.75 feet). The map indicates about 21 feet of overburden in the 

same area. The surface of the slurry pond was about 28 feet above the mine roof. 

There is a lack of detailed information on the overburden material (e.g., type, thickness, 

competence, etc.) above the mine at the 1994 breakthrough location. Neither the MSHA 

interviews nor the sealing plan identified the lithology or competence of the mine overburden. 

Based on the Triad drilling data, and assuming some degree of lateral stratigraphic continuity at 

the site, the overburden likely consists of natural, unconsolidated material (colluvium), sandstone 

with about two feet of shale above the Coalburg coal seam. The mine map shows that 25 inches 

of shale was mined, but it is not clear if the shale was above or interbedded with the coal. 

There is nothing in the record on the mine roof or pillar conditions at the 1994 breakthrough. 

However, it was indicated in the MSHA interviews that the last 20 feet of the entry might not 

have been roof bolted. This is not an uncommon practice and is not a violation of the MSHA 

regulations. The regulations provide that miners work under a supported roof. However, 

continuous mining equipment can remove coal about 20 feet beyond the last row of roof supports 

while still protecting the operator. 

3.2.3 Analysis: Given the shallow cover at the 1994 breakthrough, expected loss of rock 

competence due to weathering, possible existence of natural fractures, and likely absence of roof 

31 
bolting near the outcrop, the roof and overburden was susceptible to caving. The added weight 

of the slurry and water may have contributed to the failure. In addition, seepage from the pool 

through the outcrop barrier may have induced piping (internal erosion) into the underground 

mine, as well as additional weathering of the rock overburden. Weakening of the strata may 

have occurred to the point where it could no longer support itself and the load above it, resulting 

in the collapse of the mine roof and at least some of the overburden. 

Depending on the expansion of the roof rock when broken, roof falls can extend upward from

two to five times the mining height (Peng, 1978). Considering the mining height of 7.75 feet at 

the 1994 breakthrough, a roof fall could have extended up to 38 feet. This would have 

intersected the surface and developed into a sinkhole. This sinkhole would have allowed slurry 

to flow into the underground mine. 

Summary

 The 1994 breakthrough was probably caused by a roof fall. 

 The mine roof at the end of Entry No. 1 may not have been bolted and may have been 

composed of partially or totally weathered rock and soils. 

 The mine roof and overlying strata was not thick enough to prevent a roof fall from

progressing up to the impoundment. 

3.3 Preventative Actions After the 1994 Breakthrough 

3.3.1 Sealing plan: On May 23, 1994, MCCC prepared an initial remedial plan in response to 

the breakthrough. The plan contained both short- and long-term corrective actions. The shortterm actions included backfilling the breakthrough with rock excavated from a nearby area, 

opening the South Mains Portal to allow for more mine drainage, and restricting miner access 

into the North Mains until the water level in the mine receded. The long-term actions included 

the development and implementation of the sealing plan. 

In a June 29, 1994, letter to MCCC, Ogden summarized the progress in developing the sealing 

plan, and identified three critical objectives related to ensuring mine safety and preventing a 

recurrence of a breakthrough. The objectives were: 

 Protect the miners in the underground mine. 

 To the extent practical, prevent future breakthroughs by limiting the quantity of seepage 

passing from the impoundment into the mine (accomplished by creating a “seepage 

barrier” and controlling water levels within the impoundment). 

 To the extent practical, limit the rapid release of impounded water and fine coal refuse 

from the impoundment should a breakthrough take place. As conceived, the seepage 

barrier would provide the material that would plug any subsided area. 

32 
On August 8, 1994, Ogden submitted the sealing plan to MCCC, which then requested MSHA’s 

approval of the plan. On August 18, 1994, Summit submitted the permit revision to DSMRE. 

The permit revision contained the sealing plan prepared by Odgen. The sealing plan had two 

primary components: (1) construct a seepage barrier within the impoundment, and (2) construct 

bulkheads within the underground mine to protect miners and the conveyer system in the North 

Mains from the consequences of a breakthrough. Further, a wet seal was designed for the South 

Mains Portal. The purpose of the wet seal was to prevent air and human entry into a large 

portion of the mine and to allow water to drain from the mine. Subsequent to MSHA’s approval 

of the sealing plan and DSMRE’s approval of the permit revision, MCCC obtained MSHA’s 

approval to install a fence instead of the wet seal. MCCC did not request a similar authorization 

from DSMRE.

The proposed seepage barrier design and location are shown in Figure 5 [Page 20]. The seepage 

barrier construction involved contour mining the Stockton coal seam and pushing the blasted 

material downslope over the outcrop barrier of the underground mine in the Coalburg coal seam. 

The minimum design thickness of the seepage barrier was one to two times the height of the 

mine, or at least 12 to 25 feet. The plan provided for the planting of vegetation on the bench and 

seepage barrier to limit erosion. 

The sealing plan provided a typical cross-section of the seepage barrier and adjacent mine 

outcrop barrier. A 45-degree subsidence angle of draw from the edge of the underground mine 

determined the “minimum toe limit for seepage barrier” (Figure 5 [Page 20]). Typically, the 

subsidence angle of draw describes the distance that trough subsidence would extend beyond the 

edge of the mine.6

 The seepage barrier was intended to plug all ground cracks that may form

within the limits of subsidence. The upper limit of the seepage barrier was the base of the 

Stockton coal seam, about 100 feet above the roof of the underground mine. The plan stated that 

the amount of cover established by the elevation of the Stockton coal seam was consistent with 

the U.S. Bureau of Mines Information Circular (IC) 8741, “Results of Research to Develop 

Guidelines for Mining Near Surface and Underground Bodies of Water” (Babcock, C. and 

Hooker, B., 1977). The IC recommends that partial extraction, room-and-pillar underground 

mines, and bodies of water be separated by solid rock that is at least five times the entry 

width (5 x 20 feet = 100 feet at the MCCC impoundment) or 10 times the mining height (10 x 10 

feet = 100 feet at the MCCC impoundment). 

A critical component of the sealing plan entailed placement of slurry along the face of the barrier 

by periodically redirecting the “discharge” of the slurry. As the slurry settles and consolidates 

along the surface of the seepage barrier, permeability is decreased and the consolidated fine 

refuse retards water movement through the barrier. The plan also stated that the pool level in the 

impoundment should be maintained as low as possible, thereby reducing the quantity of clear 

water in the impoundment and the hydraulic head.

 6

 Trough subsidence normally forms from pillar crushing or pillar extraction in the underground mine and 

is characterized by a broad dish-shaped depression at the ground surface. Tension cracks occur at the outer limits of 

the depression. This is in contrast to sinkhole subsidence, which is commonly formed from inter-pillar roof 

collapse. Sinkhole subsidence may result in relatively narrow and deep depressions that do not extend far beyond 

the edge of the mine entry. The sinkholes may extend beyond the edge of the mine entry when the land surface is 

composed of unconsolidated material and that material flows into the mine.

33 
The sealing plan narrative also suggested that as the discharge of the relatively dense, fine refuse 

slurry progresses up the face of the seepage barrier and replaces the clear water, seepage into the 

underground mine should progressively decrease. The plan speculated that the potential for a 

breakthrough should be considerably reduced once the general pool level increases above the 

upper limits of the seepage barrier. It is noteworthy that the 2000 breakthrough occurred when 

the pool level was about 15 feet below the upper limit of the seepage barrier. 

Summary 

The stated purpose of the sealing plan was to: 

 Protect the miners by installing bulkheads off the North Mains. 

 Inhibit seepage into the underground mine by constructing a seepage barrier, limiting the 

water levels in the impoundment, and directing slurry against the seepage barrier. 

 Limit rapid release of future discharges because the seepage barrier would plug any 

breakthrough. 

3.3.2 Technical and programmatic concerns: Under the regulations, both MSHA and DSMRE 

approval of the sealing plan was required. OSM examined the sealing plan and the permit 

revision, documents pertaining to the MSHA and DSMRE reviews, and certifications and 

photographs of the construction activity. Several key issues in the design and construction of the 

sealing plan may have contributed to the 2000 breakthrough. These are discussed below. 

3.3.2.1 Seepage barrier permeability and slurry coating: The stated purpose of the 

seepage barrier and slurry coating was to minimize infiltration of the impounded water and slurry 

into the underground mine. MCCC also asserted that the seepage barrier would limit the rapid 

release of water and slurry should a breakthrough occur.

According to the sealing plan, spoil would be pushed downslope in thick lifts and then graded to 

the approved slope configuration. Slurry would then be directed along the barrier by periodically 

redirecting the slurry discharge. Settling and consolidation of slurry was intended to further 

reduce seepage due to the resultant low permeability. As addressed below, the seepage barrier 

would be permeable, highlighting the importance of the slurry coating. 

MSHA’s September 9, 1994, letter to MCCC on the proposed sealing plan indicated a concern 

for material segregation and recommended that the material be placed in horizontal lifts. Also, 

DSMRE, in its October 24, 1994, letter on the permit revision, asked MCCC to address 

compaction. Ogden’s responses of October 3, 1994, and November 9, 1994, indicate that they 

did not believe that compaction and gravity segregation was a matter of concern. Ogden 

recognized the potential for seepage into the underground mine. Ogden noted that the seepage 

could cause piping of fine material and that this could result in instability of the seepage barrier.

However, Ogden stated that any instability resulting from a collapse or breakthrough would be 

“choked off” given the expected gradation of the seepage barrier. Ogden said that the function 

of the seepage barrier was to provide bulk and sealing in the event of a collapse or breakthrough. 

34 
Ogden contended that the primary seepage control would be provided by the fine refuse sealing 

of the face of the barrier, reducing the potential for piping of material through the outcrop 

barrier.

In the October 1994 response, Ogden also described general guidelines for barrier material 

placement: “Dozers and excavators can place material on the outslope with dozers following the 

material downslope. Material may also be trucked down along the face and spread with dozers if 

deemed necessary by MCCC personnel. Any lifts that are placed should not exceed 20 feet in 

thickness. Material larger than 5 to 6 feet in diameter should be isolated in the fill or moved to 

the toes to provide additional stabilization in a working pad that displaces mud and fines. During 

construction, larger rock will naturally segregate and roll to the toe and supplement the working 

pad.” 

Despite the plan stating that the lifts would not exceed 20 feet, the typical cross-section for the 

designed barrier profile shows that the toe of the seepage barrier is 22 feet thick (measured 

perpendicular to the slope). Consequently, the barrier could be constructed in a single lift, 

parallel to the slope, and still essentially be in compliance with the plan. The “push-down” 

method of construction would limit the depth of compaction to only one to one and one-half feet 

below the surface (Skelly and Loy, 1978). In the case of horizontal-lift construction, a minimum

of 20 vertical feet for each lift would result in at least five lifts in a 100-foot high seepage barrier. 

This horizontal-lift construction method, however, would result in only thin bands of compacted 

material between uncompacted layers more than 18 feet thick. Neither approach significantly 

reduces permeability and would allow seepage to pipe fine material into subsidence openings. 

According to photographs (examples are provided in Photos 9 through 14 [Pages 36 through 41]) 

taken during the seepage barrier construction, the seepage barrier appears to have been 

constructed by dumping spoil downslope and dozing the material to final grade. Consequently, 

the spoil was placed as a single lift, at times greater than 30 feet thick measured perpendicular to 

the slope (Figure 4 [Page 18]). The photographs also confirmed that some gravity segregation 

occurred, potentially resulting in higher seepage barrier permeability at its base. The base of the 

seepage barrier is near the Coalburg coal seam outcrop. 

The sealing plan stated that seepage from the impoundment would be limited to 10-7 centimeters 

per second (cm/sec) if the “fine refuse is deposited in the impoundment” and “the pool level is 

maintained as low as possible.” This seepage rate equates to 0.00028 feet per day or 3,528 days 

per foot. The permit, however, does not contain test results or a quantitative analysis to support 

the 10-7 cm/sec permeability rate. Further, the sealing plan does not specify the thickness of the 

slurry coating necessary to achieve that permeability. The permit also stated that the 

permeability of the spoil material used to construct the seepage barrier would vary and could not 

be estimated. 

Research conducted by the Bureau of Mines found flow rates through spoil derived from massive 

gray sandstone ranged from 1.2x10-3 to 4.9x10-3 cm/sec (3.37 to 13.82 feet per day or 0.3 to 0.07

days per foot) (Hawkins and Aljoe, 1991). The Triad investigation independently confirmed 

high permeability of the seepage barrier material, which was largely sandstone-derived spoil. 

35 
Photo 9. Construction of Seepage Barrier (Dozer Work) - March 6, 1995. Source: GAI. 

The work is being conducted at the southwest side of the impoundment. 

36 
Photo 10. Construction of Seepage Barrier (End Dumping by Rock Truck) - March 6, 

1995. Source: GAI. The work is being conducted at the southwest side of the 

impoundment. 

37 
Photo 11. Construction of Seepage Barrier (Long View of Dozer and Truck) - March 6, 

1995. Source: GAI. The work is being conducted at the southwest side of the 

impoundment. Pool elevation 1,000 feet msl. Mine roof elevation 964 feet msl. 

 

38 
Photo 12. Seepage Barrier by 2000 Breakthrough (During Construction) - April 24, 1995. 

Source: GAI. The 2000 breakthrough area is located at the left-center of the photo. Pool 

elevation 1,000 feet msl. Mine roof elevation 973 feet msl. 

39 
Photo 13. Seepage Barrier by 2000 Breakthrough (During Construction) - June 8, 1995. 

Source: GAI. The 2000 breakthrough area is located at the left-center of the photo. Pool 

elevation 1,001 feet msl. Mine roof elevation 973 feet msl. 

40 
Photo 14. Seepage Barrier by 2000 Breakthrough (After Construction) - June 26, 1995. 

Source: GAI. The 2000 breakthrough area is located at the left-center of the photo. 

Pool elevation 1,006 feet msl. Mine roof elevation 973 feet msl. Contour bench elevation 

1,075 feet msl. 

 

41 
Triad collected a bulk sample from the seepage barrier and estimated the permeability to be 10-3

cm/sec or about 2.8 feet per day. 

The permeable nature of the seepage barrier highlights the importance of the slurry coating along 

the barrier. However, the sealing plan did not explain how the slurry coating process was to be 

conducted. Neither a timetable for moving the slurry discharge lines nor the required thickness 

of the slurry coating were discussed in the sealing plan. 

3.3.2.2 Impoundment pool elevation: Another method of controlling seepage identified 

in the sealing plan relates to limiting the elevation of the pool and the depth of water above the 

settled slurry. This minimizes hydrostatic pressure at the barrier interface, thus limiting water 

infiltration through the spoil. However, the original plan did not indicate specific pool elevation 

limits above the slurry level that would be maintained. Only maximum pools were indicated on 

the supplied cross-sections. Thus, no operational controls for limiting the amount of hydrostatic 

head above the rising slurry level were in place. 

3.3.2.3 Seepage barrier stability: To be effective, the seepage barrier must be stable 

against slides that would expose the outcrop barrier. A reasonable calculation of the barrier’s

“safety factor” requires that the engineering parameters, shape, and dimensions of the structure 

be accurately modeled. 

The sealing plan contained a stability analysis of the seepage barrier and its slurry foundation. 

OSM found deficiencies in the analysis. As addressed in Section 3.5.5, OSM’s review indicates 

that the seepage barrier stability did not contribute to the breakthrough. However, the issues 

identified below indicate that MCCC and Summit did not properly analyze the stability. 

 The analysis used a 0.05 pore pressure ratio for both the seepage barrier and foundation. 

This value indicates only 10 percent saturation of the barrier and foundation. The 0.05 

pore pressure ratio is not appropriate for the foundation because the foundation is 

saturated. Also, as the pool level increases, the seepage barrier will become increasingly 

saturated. The 0.05 pore pressure might be acceptable for the seepage barrier if it was 

constructed of impermeable material and effectively compacted. However, given the 

lack of compaction discussed above and the permeable nature of the spoil, a higher value 

would be more appropriate, representative, and conservative. 

 For the seepage barrier foundation, the analysis employed friction-angle, cohesion, and 

unit-weight values for consolidated slurry (33°, 0 lb./ft.2

, and 100.1 lb./ft.3, respectively) 

rather than unconsolidated slurry (22°, 0 lb./ft.2

, and 70 lb./ft.3). Summit obtained this

data from the 1983 Esmer & Associates, Inc. (Esmer) impoundment plan. The data may 

not have reflected the conditions at the time the seepage barrier was constructed. 

Laboratory testing was not done to confirm these values at the time the seepage barrier 

was constructed. 

OSM performed its own stability analysis of the designed seepage barrier (Appendix 6). The 

analysis assumed the barrier and slurry were saturated and it used strength parameters for both 

consolidated and unconsolidated slurry. The analysis also assumed that the natural material 

42 
underlying the seepage barrier was soil. The results indicate that the designed barrier has a 

safety factor as low as 1.3, compared to the Summit estimate of 1.6. While lacking site-specific 

parameters to increase confidence, the OSM stability analysis indicates that the seepage barrier 

would be stable at this lower safety factor. 

3.3.2.4 Plugging of future breakthroughs: The sealing plan contended that the seepage 

barrier needed to be of sufficient thickness to provide a volume that would adequately plug an 

opening into the mine created by a breakthrough. Whereas the sealing plan specified that the 

seepage barrier should be one to two times the maximum 12-foot mining height, it did not 

explain how this thickness was sufficient to plug a future breakthrough. The plan also did not 

address the characteristics (e.g., mechanism, size, location) of potential failures that should 

influence the plugging effectiveness of the barrier. For example, the plan did not assess the 

height that an underground mine roof fall could extend upward. Roof caving will create sinkhole 

subsidence if the depth of solid rock overburden is less than the height of the roof cave. Figure 5 

(Page 20), which is based on the sealing plan cross-section, shows the height that a roof cave 

could extend upward based on five times the mining height (Peng, 1978). As shown on the 

figure, a roof cave could extend nearly up to the surface of the seepage barrier for a location with 

a 70-foot outcrop barrier and a 10-foot mining height (conditions similar to the 2000 

breakthrough). At the narrowest barrier location (35-foot wide barrier and about 7.5-foot mining 

height), a roof cave could extend to the surface of the seepage barrier. Such an assessment by 

MCCC would have indicated the possible need for other preventative measures.

3.3.2.5 Dimensions and stability of the outcrop barrier: Sections 2.1.3 and 2.1.5 address 

the outcrop barrier dimensions, openings in the barrier, fractures in the barrier, and surface 

disturbance over the barrier. MCCC did not conduct a geotechnical investigation to determine 

the nature and width of the outcrop barrier. Based on the mine maps, the barrier width ranges 

from about 35 feet to more than 300 feet, and the overburden thickness at the mine limit ranges 

from about 13 feet to greater than 100 feet. At the western side of the impoundment, an entry 

has extended through the outcrop barrier to the surface. This “punchout” may have been sealed 

with concrete, but OSM could not find written documentation of the closure. Vertical fractures 

in the outcrop barrier may exist. Finally, the surface of the outcrop barrier has been disturbed by 

the construction of access roads. 

 

The effectiveness of the seepage barrier in preventing a breakthrough, or allaying the effects of a 

breakthrough, is partly dependent on the conditions of the outcrop barrier and mine roof. 

Conceivably, sufficient data might have identified particularly thin and/or weak zones in the 

outcrop barrier and mine roof that would have warranted local adjustments to seepage barrier 

design and/or construction (increasing the size of the seepage barrier, applying a thicker coat of 

fine refuse, etc.). It appears, however, that the outcrop barrier, pillar stability, and mine roof data 

available during the development of the sealing plan was limited, or if available, was not used to 

assess possible subsidence impacts. The Triad drilling in Section 3.5.1.3 revealed a greater 

portion of the outcrop barrier to be composed of colluvium than what is indicated in the sealing 

plan. The sealing plan’s cross-section (Figure 5 [Page 20]) shows that a solid coal seam extends 

from the mine to the surface. The cross-section does not contain any notations concerning the 

nature of the material overlying the coal. However, the plan states that the overburden consists 

primarily of “sandstone with some shale.” During the MSHA interviews, an MCCC consultant 

43 
stated that the cross-section was not intended to illustrate the composition of the outcrop barrier. 

While the cross-section may not have been intended to show the actual composition of the 

outcrop barrier, the cross-section and “sandstone and some shale” statement together indicate 

that the outcrop barrier was composed of solid coal and rock. 

The seepage barrier design did not appear to consider surface disturbance in the outcrop barrier 

area. For example, at the 2000 breakthrough location, the mine map indicates a road or diversion 

ditch below the Coalburg coal seam cropline, and the June 1, 1989, DSMRE aerial video shows a 

road above the cropline. These surface disturbances are not shown on the sealing plan crosssection. 

 

Using the 45-degree subsidence angle of draw, Figure 5 (Page 20) shows the lateral extent of 

subsidence for three outcrop barrier widths. These outcrop barrier figures are measured from the 

bottom of the Coalburg coal seam mine limit to the cropline. 

(1) 35 feet 

This width represents the narrowest outcrop barrier (at the entry adjacent to the punchout located 

at the western side of the impoundment) as measured by OSM on the 100-scale map attached to 

the sealing plan. 

(2) 70 feet 

This width represents the outcrop barrier at the 2000 breakthrough location. 

(3) 110 feet 

This width represents the “typical seepage barrier section” contained in the sealing plan. 

For the outcrop barrier width (70 feet) at the 2000 breakthrough, subsidence with a 45-degree 

angle of draw would intercept near the base of the seepage barrier. For the narrowest width of 

the outcrop barrier (35 feet), subsidence with a 45-degree angle of draw would extend to the toe 

of the seepage barrier. The “typical seepage barrier section” did not provide consideration for 

the worst-case subsidence scenario (35 feet). 

During the MSHA interviews, a GAI consultant to MCCC, who had worked for Ogden at the 

time of the sealing plan preparation, stated that the cross-section was drawn to size the seepage 

barrier based on “typical” outcrop barrier conditions. The consultant suggested that the section 

was not intended to represent either the minimum or maximum conditions or to distinguish solid 

from weathered coal. Thus, a single outcrop barrier width was used for the seepage barrier 

design. 

Also, the sealing plan did not provide complete and accurate information on the conditions of the 

outcrop barrier as follows: 

44 
 The sealing plan did not provide correct information on the width of the outcrop barrier. 

During the review of the permit revision, DSMRE requested MCCC to locate and orient 

the stability cross-section to a particular mine map (October 24, 1994, deficiency letter, 

item 5.f). However, at the location provided in Summit’s response for MCCC, the mine 

map shows the outcrop barrier to be about 400 feet wide, not 110 feet as indicated on the 

cross-section. 

 The sealing plan did not provide information on the mine roof material or its competence. 

Information on roof material could have been obtained through exploration drilling. 

Some of this information could have been obtained from observations of the conditions in 

the North Mains. 

 The sealing plan did not indicate that exploration was conducted to determine the 

condition of the outcrop barrier material. The plan also does not indicate that exploration 

was conducted to validate the horizontal distance between the underground mine and the 

cropline or vertical distance to the surface above the mine void. These shortcomings in 

the sealing plan development were confirmed in the MSHA interviews. While a portion 

of the outcrop barrier was covered with slurry, drilling to validate the location of the mine 

boundary and nature of outcrop barrier and mine roof material was still possible. 

 The sealing plan did not address the methods proposed to seal the punchout (along the 

western side of the impoundment) or the portals (along the northeastern side of the 

embankment). 

3.3.2.6 Potential effects of blasting: Surface blasting near underground mines has the 

potential to damage the mine roof. The sealing plan contained a blasting plan, but the plan did 

not contain an assessment of the potential for blasting impacts on the underground mine roof. 

OSM’s review, as addressed in Section 3.5.3, did not indicate that blasting contributed to the 

breakthrough. However, the issues identified below indicate that MCCC and Summit did not 

fully analyze the effects of blasting. 

With regard to the blasting plan’s assessment of potential impact, the permit reviewer asked 

MCCC to: (1) specify how the slurry impoundment and underground mine will be protected 

from adverse impacts of blasting, and (2) discuss the possibility of subsidence and any adverse 

effects (October 24, 1994, deficiency letter, item 4.f). Summit responded that subsidence 

potential was addressed in the 1984 Esmer report submitted with Amendment #1. However, the 

Esmer report merely states “It is not anticipated that subsidence will be a problem, since the 

underground mines are situated only beneath the perimeter of the impoundment site and do not 

extend for any appreciable distance directly below the proposed structure.” The Esmer report 

does not address the subsidence potential that could be caused by blasting. The permit revision 

only provides blasting control limits with respect to the underground mine seals. Even in this 

case, it is not clear whether the blasting limits apply only to seals located at the bulkheads off the 

North Mains, or whether they also apply to the seals at the entrance to mining areas #1 and #2 

(Figure 2 [Page 4]). 

45 
DSMRE’s regulations (405 KAR 16:010 Section 3) require that DMM and MSHA approve 

surface-mining activities, including blasting designs, if they will be conducted within 500 feet of 

an active underground mine. After DSMRE receives the design from the permit applicant and if 

the underground mines are active, DSMRE submits the design to DMM and MSHA for their 

approval. The design prepared by Summit incorrectly stated that the underground mine was 

abandoned and it did not identify the fact that the blasting was related to the sealing plan. 

Portions of the mine had been sealed off and were “inactive” but not “abandoned.” Based on the 

statement in the design that the mine was abandoned, and apparently without knowledge of the 

purpose of the blasting, DMM recommended that DSMRE approve the blasting. OSM’s review 

also noted that Summit, in a November 21, 1994, correspondence to DSMRE, said that seals in 

the underground mine would be inspected during blasting, but did not say how this would be 

done in an abandoned mine. Finally, there is no record in DSMRE’s file that MSHA either 

approved or disapproved the blasting design. 

The blasting design incorrectly calculated the powder factor (PF), which is the weight of 

explosive per cubic yard of rock to be blasted. The design calculated a PF of 0.22 for a 25-foot 

deep blast hole. Such a blast may not have had enough explosive energy to break the rock 

sufficiently to allow removal. The actual PF was 0.45 for a 12-foot hole. 

3.3.2.7 Storage and control of breakthrough water in the underground mine: The 

sealing plan did not contain adequate contingency measures in the event of another 

breakthrough. The plan called for the construction of the bulkheads to prevent the water and 

slurry from entering the North Mains and wet seals at the South Mains Portal to allow the release 

of the liquid to the surface. These features address the protection of the mine workers, but did 

not provide for protection of the public and environment in the Wolf Creek watershed. 

Observations of key elements of this part of the sealing plan are as follows: 

 Bulkheads: The plan assumed an 18-foot head to design the bulkheads adjacent to the 

North Mains. The 18-foot head estimate was based on the depth of water that would 

push against the bulkheads in the event of another breakthrough. The depth, in turn, was 

based on calculations indicating that water from a future breakthrough would flow out the 

South Mains Portal. Considering the inability of MCCC to determine the flow 

constrictions within the mine, it would have been prudent to assume a high head potential 

in the design of the seals. 

The sealing plan required the bulkheads to be comprised of three and one-half foot thick 

reinforced, poured concrete structures placed against existing seals located off the North 

Mains. Subsequent to DSMRE’s approval of the bulkhead, MCCC submitted changes to 

MSHA, but not DSMRE. MSHA approved the changes. The revised plan required onefoot thick reinforced gunite (shotcrete) to be placed against the existing seals. 

 Protection of residents, property, and the environment: The sealing plan would allow a 

breakthrough to freely drain through the South Mains Portal into Wolf Creek. Coldwater 

Fork would be protected by the bulkheads. During the review of the permit revision, 

DSMRE asked MCCC to address preventative measures for intercepting and controlling 

water (blowouts) from the underground mine (October 24, 1994, deficiency letter, item

46 
4.g.). Summit responded that, “The preventative measures to be implemented for 

intercepting the water is the Impoundment Sealing Plan as proposed by Ogden. The 

release of the water is through the wet seals [at the South Mains Portal] as proposed by 

Ogden.” The sealing plan did not provide for the interception or control of breakthrough 

water and slurry that would drain from the South Mains Portal. 

The DSMRE permit reviewer asked MCCC to provide information on slurry injection 

into the underground mines (October 24, 1994, deficiency letter, item 9.f and 10.a-c). 

The reviewer apparently was concerned about the slurry injection notations on the 400-

scale mine map attached to the sealing plan. Summit responded that the revision does not 

address slurry injection into the mine. However, the injected slurry should have been 

discussed in the sealing plan because it could reduce the capacity of the underground 

mine to store a future breakthrough. 

3.3.2.8 DSMRE approval and implementation: Additional problems relating to the 

approval and implementation of the sealing plan are enumerated as follows:

 Permit review and inspection: None of the permit maps provided a comprehensive 

illustration of the full extent and stages of the embankment and impoundment 

construction. While these features are shown on map sheets (generally on seven separate 

sheets per construction stage) in the 1984 Esmer impoundment design, it undoubtedly 

was cumbersome for the permit reviewer to correlate the Esmer design with the surface 

features shown on the permit maps. Also, it was likely difficult for the DSMRE inspector 

to correlate the field conditions with the Esmer design and subsequent permit revisions. 

During the review of the permit revision, DSMRE asked MCCC to show the extent of the 

abandoned underground mine on the Mining and Reclamation Plan (MRP) map (October 

24, 1994, deficiency letter, item 4.g). Summit responded “The extent of underground 

mines have been shown on other maps. It would not benefit anyone to clutter the MRP 

map with more information.” Summit is correct in stating that the underground mines 

are shown on other maps (map attached to the 1994, sealing plan and the map contained 

in July 23, 1984, Esmer impoundment design). However, it undoubtedly was awkward 

for permit reviewers and inspectors to correlate permitted surface features with the 

underground mines. This may explain the permit reviewer’s acceptance of Summit’s 

statement that blasting would not be conducted within 500 feet of an active underground 

mine. As another example of the difficulty of correlating permitted features with the 

underground mines, Summit, in Amendment #2 (in response to item 35.3 of the permit 

application), stated that the proposed coarse refuse, non-impounding embankment did not 

overlay an underground mine. However, portions of the South Mains, including the 

entries to the South Mains Portal, appear to lie under the proposed coarse refuse 

embankment. In this case, the applicant would have been required to describe the 

potential effects of subsidence on the structure. 

 The public interest: The permit revision was classified as a “minor” rather than a 

“major” revision. According to Kentucky regulations at 405 KAR 8:010 Section 

20(2)(a), a revision shall be deemed a major revision if the Cabinet determines that the 

47 
proposed change is of such scope and nature that public notice is necessary to allow 

participation in the Cabinet’s decision by persons who have an interest which may be 

adversely affected by the proposed change. By classifying the revision as minor, the 

application for revision did not require public notice. Considering the adverse 

consequences that could occur if the sealing plan did not function as designed, public 

notice should have been required. 

 Certifications: The actions taken under the sealing plan were not fully certified 

(Appendix 7). MCCC did not prepare a certification of design (DSMRE form SMP-31) 

for the seepage barrier. DSMRE requires such certifications for impoundments, excess 

spoil fills, roads, etc. While the regulations do not specifically address certification of

seepage barriers, DSMRE could have required certification of the seepage barrier design 

because the barrier is a component of the impoundment plan.

An as-built stability analysis, for certification purposes, of the seepage barrier was not 

prepared, even though its final configuration was significantly different from the 

designed 2:1 outslope (two feet horizontal for every foot vertical). The final slope was 

about 3:1. This may have had a positive effect by increasing the thickness of the seepage 

barrier. However, it may have potentially decreased the stability of the barrier 

foundation because the seepage barrier extended farther out over the slurry. 

The annual certifications did not address the slurry coating of the seepage barrier. This 

may have been related to the lack of specifications concerning this requirement; and 

therefore, the weekly inspector may not have been aware of the requirement. See Section 

3.3.2.1 for additional discussion. 

The annual certifications did not address the water monitoring conducted at the South 

Mains Portal. The 1995 certification form identified “leakage,” but the attached narrative 

did not address the leakage. The 1998 annual certification did not address the bubbling 

that occurred in the impoundment in February 1998. Bubbling is an indication of 

leakage and, therefore, should have been addressed in the annual certification.

DSMRE’s certification files for the impoundment permit (Permit Number 680-8002) and 

the underground mine permit (Permit Number 680-5012) do not contain any certification 

documentation or reference to the bulkheads. The bulkheads are a component of the 

sealing plan and should have been certified. The design approved by MSHA required 

five steel reinforcing bars at the top and bottom of each bulkhead. The bars were 

supposed to extend into the mine roof and floor. However, a construction drawing that 

MCCC supplied to the contractor installing the bulkheads showed only three steel bars at 

the top and four at the bottom. 

3.3.2.9 Impoundment monitoring: Discharges out of the South Mains Portal were 

monitored on a weekly basis starting in July 1994. Monitoring at the South Mains was addressed 

in the short-term plans prepared after the 1994 breakthrough. However, the results of the 

monitoring were not submitted to DSMRE nor assessed in the annual certifications. The plan did 

not contain any in-mine monitoring. 

48 
3.3.2.10 Employee awareness: The MSHA interviews revealed that not all of the MCCC 

personnel responsible for the impoundment had specific knowledge concerning the underground 

mine and its outcrop barrier and the intent of the seepage barrier. Consequently, early signs of 

leakage, if ever observed, may not have been identified as related to the underground mines. 

This is the case with the GAI employee who conducted the weekly impoundment inspections. 

The employee was never given drawings of the outcrop area or barrier seal, and he had no 

knowledge of the outcrop barrier. The MCCC preparation plant superintendent and the 

supervisor for the night shift had not seen, or could not remember seeing, the sealing plan and 

they had no knowledge about the outcrop barrier. Also, the supervisor was not aware of the 

bubbling reported in the impoundment during February 1998, or of the remedial action. 

Summary

 Seepage barrier compaction and permeability (3.3.2.1). The sealing plan did not provide, 

except in a very general manner, any construction specifications for the method of 

placement and compaction. The plan would result in a permeable seepage barrier due to: 

(1) gravity segregation of large rocks at the base of the seepage barrier, and (2) lack of 

compaction. The seepage barrier appears to have been constructed in a single lift at times 

greater than 30 feet thick. The sealing plan stated that the lifts would not exceed 20 feet. 

MCCC did not provide permeability test results or a quantitative analysis to support its 

permeability estimate related to seepage from the impoundment. Also, the permit did not 

address the thickness of the slurry coating necessary to inhibit seepage.

The sealing plan stated that slurry would be directed along the barrier to inhibit seepage 

into the barrier. However, the plan does not: (1) provide specifications on how this 

action would be conducted or (2) specify the required thickness of the coating. MSHA’s 

interviews found that the slurry was discharged at only one location. 

 Impoundment pool elevation (3.3.2.2). The sealing plan stated that MCCC would limit 

the depth of water above the slurry level. However, the plan does not provide 

specifications on how this action would be conducted. 

 Seepage barrier stability (3.3.2.3). MCCC did not conduct material testing to verify the 

strength parameters used in the stability analysis and the analysis also used inappropriate 

saturation conditions. OSM’s stability analysis of the designed seepage barrier indicates 

that it is stable; however, the analysis indicates that the safety factor is lower than the 

estimate in the permit revision. 

 Plugging of future breakthroughs (3.3.2.4). The sealing plan indicated that the seepage 

barrier would plug future breakthroughs. However, the plan did not assess the seepage 

barrier’s plugging capabilities for the various types of openings that could develop in 

response to subsidence. OSM’s review indicates that sinkhole subsidence could extend 

through the designed barrier. Such an assessment by MCCC would have indicated the 

need for alternative preventative measures. 

49 
 Dimensions and stability of the outcrop barrier (3.3.2.5). The sealing plan does not 

indicate that MCCC conducted testing to: (1) verify that the outcrop barrier was 

accurately shown on the maps, and (2) determine the nature and competence of the 

outcrop barrier and mine roof. The sealing plan contained a cross-section showing a 

“typical” outcrop barrier rather than the narrowest barrier, and estimated, using the 

typical drawing, that subsidence would not extend to the base of the seepage barrier. 

OSM’s estimated the extent of subsidence based on the narrow barrier and found that it 

would extend into the base of the seepage barrier. Neither the sealing plan, nor previous 

permitting actions, addressed how MCCC would seal an existing punchout and set of 

portals. 

 Potential effects of blasting (3.3.2.6). The sealing plan addressed blasting; however, it 

did not assess the impacts that blasting could have on the underground mine roof. The 

revision did not contain any vibration limits to protect the roof. The revision stated that 

the underground mine was abandoned, and DMM recommended approval of the blasting 

based on the abandoned status. Further, apparently the blasting plan submitted to DMM 

did not address the impoundment. With regard to blasting near the underground mine 

seals, the revision incorrectly calculated the blasting PF and proposed a low PF that may 

not have been sufficient to break the rock. 

 Storage and control of breakthrough water in the underground mine (3.3.2.7). The 

sealing plan used a water depth to design the bulkheads based on the assumption that the 

South Mains Portal would handle future breakthroughs. A more conservative water 

depth would have been appropriate. After MSHA and DSMRE approved the sealing 

plan, MSHA approved a bulkhead design change. However, MCCC did not request 

DSMRE’s approval of the change. The sealing plan did not address how future 

breakthrough discharges would be contained within the permit area. The sealing plan did 

not address how slurry, previously injected into the underground mine, could affect future 

breakthrough discharges. 

 DSMRE approval and implementation (3.3.2.8). The permit maps do not contain 

sufficient details on the embankment and impoundment. Also, the permit maps do not 

enable a concise correlation of the surface and underground mine features. The permit 

revision was treated as a “minor” rather than “major” revision, and consequently, public 

notice of the proposed revision was not required. MCCC did not prepare a DSMRE 

certification of design for the seepage barrier. The actions taken under the sealing plan 

were not fully certified. The constructed bulkheads were not certified, and an as-built 

stability analysis for the seepage barrier was not performed. An as-built stability analysis 

for the seepage barrier was warranted because of the difference between the constructed 

and designed configurations. Also, the annual maintenance certifications do not assess 

the drainage monitoring at the South Mains Portal. 

 Impoundment monitoring (3.3.2.9). The South Mains Portal monitoring data was not 

submitted to DSMRE nor assessed in the annual certifications. 

50 
 Employee awareness (3.3.2.10). The MCCC employees responsible for the 

impoundment and the weekly inspector were not fully aware of the extent of the 

underground mines and the purpose of the sealing plan. 

3.4 MCCC EAP

The EAP, as addressed in MSHA Program Information Bulletin No. P94-18 (Appendix 9), is 

intended to satisfy the regulatory requirements at 30 CFR 216-3(e). The EAP is not required by 

the OSM regulations. MCCC submitted an EAP to MSHA on April 10, 1991 (Appendix 8). The 

EAP was approved on June 14, 1991. The approved EAP addresses procedures to be taken when 

adverse conditions develop in the embankment. It includes emergency warning and evacuation 

notices to federal and state agencies, including MSHA, DSMRE, DMM, Sheriff’s Office, 

Kentucky State Police, and DES. According to the MCCC transmittal letter to MSHA, copies of 

the EAP would be provided to these agencies subsequent to MSHA’s approval of the plan. 

The EAP includes a map showing only the area that could be impacted in the event of an 

embankment failure. The impacted area is shown as the portion of Wolf Creek located 

downstream from the embankment. The map does not show the areas that could be affected by a 

breakthrough into the underground mines (e.g., Big Andy Branch and Coldwater Fork). The 

approved EAP provides that any decision to evacuate the area would be made concurrently by 

MSHA, DMM, and DSMRE. 

 

MSHA’s interviews of MCCC personnel indicated that the supervisory personnel were not 

consistently knowledgeable of the provisions of the EAP. One supervisor was not aware that the 

plan required downstream notification. The security chief was not aware of the plan. 

The MSHA interviews indicate that MCCC generally complied with the requirements of the 

EAP following the 2000 breakthrough. MCCC initiated corrective action, monitored stream

conditions, and notified the federal and state agencies. 

Summary

 The EAP did not cover all of the surface areas that could be affected by a breakthrough. 

 MCCC generally complied with the requirements of the EAP following the 2000 

breakthrough. 

3.5 2000 Breakthrough

The breakthrough occurred on October 11, 2000, at the end of a 50-foot long, 20-foot wide deadend entry in the underground mine in the Coalburg coal seam. This breakthrough resulted in a 

slurry discharge from the South Mains Portal. The slurry also destroyed one or more of the 

ventilation seals off of the east-west mains and the bulkheads off the North Mains, inundated the 

conveyor haulage system in the North Mains, and discharged from the Number 2 North Portals. 

At the time of the breakthrough, the pool was at 1,060 feet msl and 87 feet above the 

underground mine roof (Figure 4 [Page 18]). The pool level then dropped by about 14 feet. An 

51 
estimated 306 million gallons of slurry drained into the underground mine, and an estimated 245 

million gallons of slurry discharged from the underground mine to the surface drainage systems. 

OSM determined the probable mechanisms for the 2000 breakthrough by reviewing the 

following: (1) information obtained from the MSHA interviews, (2) the impoundment permit 

files and 1-C mine map files, (3) photographs, (4) various other information, such as drill hole 

data, precipitation records, mine discharges, seismic records, and pool levels, and (5) OSM 

modeling. 

OSM determined that the mine entries or other openings did not extend to the surface near the 

2000 breakthrough prior to October 11, 2000. This determination was based on a comprehensive 

review of the permit files, including maps, as well as photographs. By the events during and 

following the breakthrough, it is clear that two important components of the sealing plan did not 

perform as anticipated. The seepage barrier failed to plug the breakthrough, and the bulkheads 

failed to prevent the slurry from entering the North Mains. 

 

3.5.1 Subsurface investigation: Triad, under contract with MSHA, conducted drilling at the 

2000 breakthrough area. The drilling provided considerable detail of the subsurface conditions. 

The drilling was primarily conducted along three lines (numbered 1, 2, and 3) that run down the 

center of the mine entry associated with the breakthrough and two adjacent entries. The drill 

holes are numbered according to the line on which they are located. Holes were also drilled 

adjacent to the lines and these holes are given an “X” or “P” designation. The drill lines and 

holes are shown on Figure 6 (Page 53). The Field Test Boring Logs generated by Triad for the 

47 drill holes were used as the primary source of the information for this section of the report. 

3.5.1.1 Location of failure: The Triad drilling confirmed that the failure occurred at the 

southwest corner of the 50-foot long, dead-end entry at Line #1, as illustrated in Figures 2, 4 

and 6 (Pages 4, 18, and 53). 

3.5.1.2 Mine and surface map accuracy: The underground mine location and 

configuration is shown on the sealing plan map. The map also shows surface contours based on 

1985 aerial photography. The underground mine rooms and pillars were superimposed on the 

topography by aligning the mine and surface survey data. The drilling, conducted under MSHA 

contract, generally confirmed the accuracy of the underground mine location and configuration 

at the breakthrough area. 

 To conduct the drilling program for MSHA, Triad conducted a land survey using both 

underground and surface survey stations to locate the underground mine in the general area of 

the breakthrough. Triad then staked the underground mine boundary on the land surface. 

Triad, under guidance from MSHA, conducted drilling in the vicinity of the 2000 breakthrough 

to verify the boundary of the underground mines as shown on the sealing plan map. The drilling 

also disclosed the types of material overlying the underground mine. The drill holes generally 

located coal and mine voids where the map showed coal and mine voids should exist. The 

drilling did not identify any missing or collapsed coal pillars. This is consistent with the mine 

map, which indicated that MCCC did not extract pillars. 

52 
Figure 6. Drill Hole Location Map. Drawn by OSM using Triad drilling data. Note: The Triad drill logs 

did not indicate that voids were encountered by holes X-4 and X-8; however, these holes, along with X-5, are located in the breakthrough erosion channel. 

53 
The drilling, holes 1-1 and 1-10, identified a void beyond the mapped mine entry (mine limit) at 

the 2000 breakthrough. These drill holes were located along the centerline of the entry. This is 

in contrast to drill hole X-9, which did not identify a void near the left side of the entry. It is not 

known whether the “missing” coal was mined or eroded during the breakthrough. However, coal 

remaining at the base of the holes (1-1, X-4, X-5, X-8) suggests that the coal was eroded and not 

mined. Except for holes 3-4 and X-15, the Triad drilling indicates that MCCC mined the total 

thickness of coal. 

In addition to showing the underground mines, the sealing plan map also presents the 

topography, various surface features and the projected cropline in the 2000 breakthrough area. 

MCCC projected the cropline by extending mine floor elevations horizontally to intersect the 

surface topography. The Triad drilling and surveying confirmed the general location of the 

projected cropline shown on the sealing plan map. At the 2000 breakthrough, the map showed 

70 feet, measured horizontally, from the end of the mapped mine limit to the cropline. 

 

3.5.1.3 Drill logs: The materials encountered during drilling (from top to bottom)

include: refuse/slurry material, combined spoil zone (the seepage barrier and material used to 

plug the 2000 breakthrough), colluvium, sandstone, shale, coal, and mine floor rock. 

As discussed in more detail in the following paragraphs, a significant portion of the overburden 

at the 2000 breakthrough was not composed of solid rock. At the end of the mine entry where 

the breakthrough occurred, the overburden, based on vertical measurements from Figure 7 (Page 

55), was composed of about 14 feet of sandstone and 11 feet of colluvium. (Note: MSHA has 

characterized this distance by a diagonal measurement of 27 feet at the end of the mine entry.

MSHA’s measurement was made along Triad Profile D-D [see Inset Figure 4, Page 18] while 

OSM’s measurement was made along Triad Profile A-A, Figure 7 [Page 55].) Further, more 

than fifty percent of the upper portion of this sandstone may have been weathered. 

At the end of the 10- to 12-foot section of “missing coal” (Figure 7 [Page 55]), the overburden is

composed of only about four feet of weathered sandstone and 15 feet of colluvium. This is in 

contrast to the sealing plan that indicates that the overburden was solid rock (Section 3.3.2.5). 

Further, the sealing plan’s cross-section and maps indicate that the horizontal distance between 

the mine limit at the 2000 breakthrough and the surface was 50 feet at the top of the coal seam

and 70 feet at the bottom of the coal seam. However, the drilling near the breakthrough indicates 

that the Coalburg coal seam extended less than half the distance from the mine limit to the 

surface. The full thickness of the Coalburg coal seam exists for only about 15 feet beyond the 

mine limit as mapped and then it thins to zero feet thick at about 33 feet from the end of the mine 

(Figure 6 [Page 53]). The Triad drill logs did not identify coal in the remaining portion of the 

70-foot wide outcrop barrier. This coal is presumed to be in a weathered condition, and it may 

have been transported downslope due to hillside creep. 

54 
Figure 7. Triad Profile A-A. From Triad Report, Cross-Section at Line #1, Figure 6. 

55 
The following summarizes the data from the Triad drilling: 

 Refuse/slurry: This material is described in the drill logs as coal refuse but most likely 

represents the unconsolidated material used to construct the drilling pad. The thickness 

varied from less than a foot along the eastern drill holes to 50 to 60 feet thick at the 

westernmost drill holes. 

 Combined spoil zone: After the 1994 breakthrough, a seepage barrier was constructed 

with spoil derived from overburden removed from above the Stockton coal seam. The 

overburden above the Stockton coal seam included colluvium, as well as weathered and 

competent sandstone. The spoil was placed downslope of the Stockton coal seam, over 

areas where underground mining had occurred. Material similar to that in the seepage 

barrier was used by MCCC during the early hours of October 11, 2000, to plug the 

breakthrough and later to construct a drilling pad. These two material layers are referred 

to as the “combined spoil zone.” Subsequently, during the expansion of the original 

drilling pad, the combined spoil zone was covered with coarse coal refuse. 

Because the two layers (seepage barrier and breakthrough plugging material) are 

composed of similar material, the drilling results could not differentiate them. 

Consequently, the surface of the seepage barrier could not be identified. The 

approximate configuration of the seepage barrier is shown in Figure 4 [Page 18]. The 

material primarily consisted of brown, clayey sand with abundant sandstone fragments 

and occasional boulders. This material was unconsolidated and soft as evidenced by the 

augering and driven, split-spoon sampling used to penetrate the zone. Typically, the 

auger is used until the driven, split-spoon sampler can no longer be advanced (commonly 

called “refusal”), at which time a rock core barrel would be used. In general, the auger 

and split-spoon drilling method was able to penetrate the material in this zone. 

The annual certification maps indicate that the seepage barrier varied from a few feet 

thick at the top (just below the Stockton coal seam) to more than 30 feet, measured 

perpendicular to that slope, at its base (Figure 4 [Page 18]). Based on the drilling data, it 

appears the seepage barrier eroded into the mine during the 2000 breakthrough. 

 Colluvium: Detection of the interface between the combined spoil zone and colluvium

was difficult since their lithologies are similar and because both zones could be 

penetrated by the driven, split-spoon sampler. The distinction between spoil and 

colluvium was made using the driller’s notes, as well as changes in texture, color, and 

organic components. The natural material itself cannot be differentiated between 

colluvium (soil transported by gravity) and residuum (soil formed in-place by the 

weathering of the bedrock). This unit was typically shown as a brown to gray, mottled 

sandy clay with few rock fragments, only an infrequent boulder, and some defined root 

zones. The unit varied in thickness from a little over 5 feet to more than 27 feet. The 

drill logs for X-4 and X-8 did not show what was termed to be “natural or colluvial 

material.” Also, the drill logs for X-5 (5.5 feet) and X-6 (4.3 feet) indicated thinner 

intervals of “natural or colluvial material” than would be expected based on a thickness 

56 
of between 10 and 15 feet in other drill holes. The drill logs for X-4, X-5, X-6, and X-8 

indicate that the colluvium was eroded during the breakthrough. 

 Sandstone: This unit was distinguished from the unit above in part by refusal of the splitspoon sampler. The sandstone was mostly medium-grained and weathered from gray to 

brown. The weathered portion was reportedly brown, soft, and friable, while the 

unweathered portion was gray and hard. The sandstone in the core samples exhibited 

frequent iron staining, fractures, and occasionally carbonaceous and shale laminations. 

Along Line 1 (Figure 6 [Page 53]), the thickness of this unit ranged from 0.0 to 64.4 feet. 

The weathered sandstone varied in thickness from 0.0 to 8.2 feet. 

The entire sandstone column at drill holes 1-1 and 1-10 (4.1 and 3.6 feet thick, 

respectively) was weathered. This sandstone would comprise the mine roof if this area 

had been mined. OSM’s review (see Coal below) indicates that the void encountered by 

the Triad drilling at drill holes 1-1 and 1-10, may have been created during the 2000 

breakthrough. In drill hole 1-2, which is located near the end of the entry where the 

breakthrough occurred, approximately half of the upper portion of the 17.6-feet thick 

sandstone interval was also weathered. The location of these three drill holes relative to 

the mapped mine entry is shown on Figure 6 (Page 53). 

The sandstone is absent at X-4 and X-8, even though the surrounding drill logs (1-1, X-5, 

and 2-7) indicate that a few feet of sandstone should have been expected. Apparently, the 

sandstone was “eroded and/or transported” during the 2000 breakthrough. Evidence of 

erosion includes (1) sandstone showing thinner than expected (at 1-10) and (2) sandstone 

boulders being detected in the mine voids (at 1-10, 1-3, and 1-4). 

 Shale: This unit is typically described as soft, gray shale. Based on the drill logs, this 

unit is relatively thin (0 to approximately 3 feet) and was noted in several of the drill logs 

where the coal was solid. The shale was typically not recorded in the holes that 

encountered mine voids. This does not appear to be a depositional feature (i.e., a “pinchout”) since the shale was consistently encountered in drill holes that penetrated coal. The 

Triad drilling does not indicate any roof falls beyond the breakthrough point. 

 Coal: The Coalburg coal seam (when encountered in the drill holes) was simply shown 

as coal and was not described as to the presence of partings, cleat and fracture 

development, hardness, etc. The solid coal in the drill logs varied in thickness from zero 

feet toward the cropline to 11.1 feet at its thickest at drill hole X-3. Excluding the area 

toward the cropline where the coal thinned as a result of weathering, the median value for 

mineable thickness of the coal was 9.2 feet. Mine void heights varied from 9.5 feet at X1 to 11 feet at 1-2 with a median value of 10.2 feet. The difference of one foot between 

the median values of the mineable coal thickness and the mine void thickness appears to 

be related, as previously discussed, to the presence or absence of the shale overlying the 

Coalburg coal seam. 

An exception to the range of coal seam thickness and mine void height was noted in the 

drill logs. First, the coal thickness in X-4, X-5, and X-8 was considerably thinner (2 feet, 

57 
1.2 feet, and 3 feet, respectively) than would be expected based on the surrounding drill 

hole information. Erosion of the upper portion of the coal into the mine during the 2000 

breakthrough may have created voids beyond the limits of mining. According to the 

mine map, these holes would not fall within the plotted underground mine mines. 

Additional evidence for the erosion is that these voids are almost 14 feet high, 

considerably higher (approximately 40 percent) than the other underground mines 

encountered in the drilling program. Erosion from the 2000 breakthrough probably 

created the voids and enlarged them by scouring the bottom of the sandstone. 

 Mine floor rock: The mine floor rock was consistently reported as soft to very soft gray, 

clay shale. This unit served as a good marker bed for establishing the bottom of the coal 

seam. 

3.5.1.4 Seepage barrier slurry coating and saturation: As addressed in Section 3.3.2.1, 

the sealing plan required slurry to be directed along the seepage barrier by periodically 

redirecting the discharge of slurry. The MSHA interviews with the weekly inspector revealed 

that slurry was pumped into the pool from only the east, upstream side of the embankment. This 

discharge location is at the opposite end of the impoundment from the 2000 breakthrough. Thus, 

it appears that an effective fine refuse layer was not in place to prevent water at the clear-water 

zone from seeping through the seepage barrier. 

Triad, during its drilling of the 2000 breakthrough area, identified the water level in the seepage 

barrier. The drilling along Line 3 indicated that the full thickness of the seepage barrier was 

saturated at the bottom of the barrier (Figure 8 [Page 59]). Line 3 is farthest from the 

breakthrough point and probably best represents the conditions prior to the 2000 breakthrough. 

3.5.1.5 Enviroscan, Inc.’s Geophysical Survey: Under contract to MSHA, Enviroscan, 

Inc., conducted misa-a-la-masse electrical profiling at the Triad drilling site. The survey 

identified two primary subsurface electrical peaks or anomalies. The electrical peaks trend 

toward, but do not reach, the known breakthrough point. Triad assessed the survey results in 

conjunction with their drill-hole data. Triad concluded that there was no evidence of a possible 

breakthrough at the anomaly locations. The electrical peaks were interpreted as responding to 

bedrock fractures or joints. 

3.5.1.6 Borehole camera analysis: DSMRE videotaped the Triad boreholes with 

a down-hole camera. Because the boreholes were cased down to the sandstone unit, the 

videotapes do not provide any information on the combined spoil zone or the colluvium. OSM 

reviewed the videotapes and observed some natural, mineral-stained fractures. The review did 

not identify any large bedding separations or fractures attributable to the 2000 breakthrough. 

Summary

 Location of failure (3.5.1.1). The failure occurred at the end of a 50-foot long dead-end 

entry.

58 
Figure 8. Triad Profile C-C. From Triad Report. Cross-Section at Line #3, Figure 6. 

** Denotes Text Added by OSM. 

59 
 Mine and surface map accuracy (3.5.1.2). The Triad drilling generally confirmed the 

accuracy of the underground mine location and configuration at the 2000 breakthrough. 

The drilling identified 10 to 12 feet of missing coal beyond the end of the breakthrough 

entry. It is not known whether the “missing” coal was mined or eroded during the 

breakthrough. However, OSM’s review, based on an examination of the drill logs, 

indicates that coal was eroded during the breakthrough. 

 Drill logs (3.5.1.3). Based on the drilling near the 2000 breakthrough, there was 

approximately 14 feet of solid rock overlain by 11 feet of colluvium measured vertically 

at the end of the 50-foot long dead-end entry. More than 50 percent of the upper portion 

of this sandstone may have been weathered. At the end of the 10- to 12- foot section of 

missing coal, the thickness of the rock overburden may have been as little as four feet of

weathered sandstone, and the unconsolidated material may have been about 15 feet 

(Figure 7 [Page 55]). At the breakthrough, the Triad drilling indicates the full thickness 

of the Coalburg coal seam extends for only about 15 feet measured horizontally beyond 

the mine limit as mapped, and then it thins to zero feet thick at about 33 feet from the 

mine limit (Figure 6 [Page 53]). However, the sealing plan cross-section and maps 

indicate that the full thickness of coal extended the total distance to the surface (70 feet 

from the mine limit to the cropline). The coal between the cropline and the coal 

encountered by the Triad drilling is presumed to have weathered. 

 Seepage barrier slurry coating and saturation (3.5.1.4). The slurry coating was not 

conducted as required by the sealing plan. The Triad drilling indicates that the total 

thickness of the seepage barrier was saturated at the bottom of the barrier. 

 Enviroscan, Inc.’s Geophysical Survey (3.5.1.5). The survey identified subsurface 

anomalies that were interpreted as bedrock fractures or joints. There was no evidence of 

a possible breakthrough at the anomaly locations. 

 Borehole camera analysis (3.5.1.6). The review did not identify any large bedding 

separations or fractures attributable to the 2000 breakthrough. 

3.5.2 Mine Discharge Data: In Appendix 10, OSM reviewed the discharge from the pond near 

the South Mains Portal to determine if the discharge provided a forewarning of the 2000 

breakthrough. The pond received surface drainage from a 10.8-acre watershed as well as from 

the 1-C underground mine. The pond discharged through an 18-inch pipe. During the weekly 

inspections, the depth of flow in the pipe was measured and recorded. 

Long-term, weekly monitoring plans for the South Mains Portal pond were contained in the 

August 8, 1994, sealing plan. The plan required the weekly inspector to immediately report to 

MSHA and MCCC any unusual change in flow that would indicate possible impoundment 

leakage. The sealing plan was attached to the August 18, 1994, permit revision. The permit 

revision’s surface and groundwater monitoring plan did not address the monitoring at the pond 

nor its importance with regard to detecting impoundment leakage. Consequently, the 

information was not submitted to DSMRE and the DSMRE inspector may not have been aware 

of the requirement. 

60 
The annual certifications, as addressed in Section 3.3.2.10, do not indicate that MCCC or GAI 

analyzed the increased flow rates from the South Mains Portal pond. 

In addition, MCCC monitored the pond discharges for compliance with the Kentucky Pollutant 

Discharge Elimination System (KPDES) permit issued by the Kentucky Division of Water 

(DOW). DSMRE incorporated the KPDES requirements into Permit Number 880-7000. The 

KPDES reports were submitted to DSMRE and DOW. 

Wyatt, Tarrant and Combs, LLP, attorneys at law, representing MCCC, submitted pond 

discharge data and precipitation information to OSM, DSMRE, and MSHA on August 10, 2001, 

and September 13, 2001. This information covered the period from January 12, 1999, through 

October 23, 2000. The pond discharge data contains the KPDES information on flow rates 

(gallons per minute) and total suspended solids (TSS). The KPDES information includes the 

South Mains Portal pond, two other ponds that MCCC states are within the influence area of the 

impoundment, and three ponds that MCCC states are located outside the impoundment influence 

area. The submittal also contains precipitation information from the National Weather Service 

(NWS) Integrated Flood Observing and Warning System (IFLOWS) station number 3193, at 

Inez, Kentucky, and station number 3194, along Wolf Creek. Station number 3193 is about eight 

miles from the impoundment. Station number 3194 is about three miles from the impoundment 

and was the primary source of information for the OSM analysis. Finally, the submittal contains 

the flow depth from the weekly inspections for the South Mains Portal pond. 

The KPDES monitoring was conducted by Blackburn Contracting, Inc. (Blackburn). Blackburn 

measured the flow rates with a flow meter to determine velocity, and they calculated the flow 

area using a chart (velocity times area equals quantity). The chart converts flow depth to area. 

MCCC’s attorney submitted Blackburn’s explanations of its measurement procedures to OSM, 

DSMRE, and MSHA on September 21, October 3, and October 11, 2001. For the South Mains 

Portal pond, Blackburn noted that it was difficult to obtain velocity “due to the discharge pipe 

being surrounded by rock. Therefore flow rates had to be estimated.” 

In its submittals, MCCC contends that the information does not indicate any “problem with the 

impoundment prior to the October 11, 2000 breakthrough.” MCCC based these conclusions on 

three findings: (1) the precipitation amounts increased during 2000 when compared to 1999 and 

resulted in higher pond discharges, (2) all six ponds showed similar trends for both 1999 and 

2000, and (3) there was a steady increase in the impoundment pool elevation. In addition, 

MCCC reported a decrease of TSS in the South Mains Portal pond and stated that this contrasted 

with an increase of TSS for the other five ponds during 2000. 

Because the IFLOWS data was not available for precipitation prior to 1999, OSM used the 

Paintsville, Kentucky, NWS data to obtain a long-term trend. Figure 9 (Page 62) shows that 

while the Paintsville and IFLOWS rates differ, they both have similar trends. 

In Appendix 10, OSM reviewed: (1) information provided by MCCC concerning discharge rates 

at the South Mains Portal pond and five other ponds, as well as precipitation amounts and TSS 

levels, and (2) South Mains Portal pond discharges and precipitation for an extended period to 

determine if there was a long-term trend. Based on this review, OSM found the following: 

61 
Figure 9. Impoundment Elevation, South Mains Portal Pond Discharge, and Precipitation. Impoundment elevation 

obtained from MCCC. Pond discharge calculated by OSM—for details see Appendix 10, Section 4. Precipitation obtained from National Weather Service, Paintsville, Kentucky and IFLOWS station number 3194. See Appendix 10, Figure 4 for data points. The discharge and precipitation lines are “trendlines” based on an eight point moving average. 

 

62 
 There was no clear, consistent trend between discharge rates and precipitation for the six 

ponds as contended by MCCC. 

 There was not a relationship between precipitation and impoundment pool elevation. 

 The TSS levels in the South Mains Portal pond discharge are not an indication of 

impoundment leakage. 

 The KPDES rates reported by Blackburn and the flow depth reported by the weekly 

inspector do not exhibit similar trends. 

 The discharge trendline analysis showed increased discharge, starting in September 1999, 

from the South Mains Portal pond which, in fact, was caused by increased drainage from

the underground mine. This increased drainage was the result of leakage from the 

impoundment into the underground mine and not related to surface runoff from

precipitation. This increased drainage was an indicator of the impending breakthrough.

 The elevated discharges in 1998 indicate an increase in the impoundment leakage into the 

underground mine. OSM could not, however, determine if the leakage was related to the 

February 1998 bubbling or to leakage at some other location within the impoundment. 

 

OSM’s review of the precipitation amounts from station number 3194 identified eight events 

with measurable rainfall in the 30 days prior to the 2000 breakthrough. The dates and amounts 

for these precipitation events are as follows: September 12, 0.04 inches; September 21, 0.2 

inches; September 24, 0.16 inches; September 25, 1.83 inches; September 26, 0.04 inches, 

September 28, 0.04 inches; October 6, 0.04 inches; and October 8, 0.04 inches. 

Summary

 The drainage out of the pond at the South Mains Portal significantly increased during 

September 1999. OSM’s review found that the increased discharge was due to drainage 

from the underground mine. Further, OSM’s review found that the increase was likely 

due to leakage from the impoundment into the underground mine and was an indicator of 

the impending breakthrough. 

 Increased leakage from the impoundment into the underground mine may have started 

during early 1998. This leakage may have been related to bubbling identified west of the 

embankment. 

 The permit revision’s surface and groundwater monitoring plan did not address the 

monitoring at the South Mains Portal pond, nor its importance with regard to detecting 

impoundment leakage. Consequently, the information was not submitted to DSMRE and 

the DSMRE inspector may not have been aware of the requirement. 

 The record does not indicate that MCCC or its consultant analyzed the discharge rates to 

determine if they indicated leakage from the impoundment into the underground mine. 

63 
 The precipitation amounts in the 30-day period prior to the 2000 breakthrough were not 

significant. 

3.5.3 Effects of Blasting: In order to construct the seepage barrier, MCCC conducted blasting 

above the Stockton coal seam. OSM reviewed (Appendix 11) blasting record adequacy, PFs 

(amount of explosive use to break the rock), vibration levels at the underground mine roof in the 

area of the 2000 breakthrough, and vibration levels at the underground mine seals. 

The review found that: 

 The blast records were incomplete. They did not contain information concerning the 

location of the blasts. Consequently, a third-party reviewer is not able to determine the 

vibration levels at any particular location within the mine except by making worst-case 

estimates. 

 The PFs are generally high, but the majority is acceptable considering the hard sandstone 

that was blasted. However, there were a number of blasts with PFs of 1.7 to 2.5. These 

could have resulted in undesirable effects such as excessive air blast, rock movement, and 

ground vibration. 

 The blasting activity did not occur directly above the 2000 breakthrough. The vibration 

levels do not appear to have been high enough to damage the underground mine roof at 

the 2000 breakthrough. The vibrations may have reached 5.6 inches per second (in/sec), 

which is considerably below the 10 to 12 in/sec level that could have caused roof 

damage. The vibrations may have caused micro-fractures to form in the mine rock and 

weakened the roof; however, the degree of weakening cannot be quantified. The Triad 

drilling did not indicate roof falls near the breakthrough. 

 The vibration levels may have been high enough to cause roof falls immediately under 

the blasts. If such roof falls did occur, the Triad drilling indicates that they did not extend 

to the breakthrough area. The vibrations under the blasts may have reached 19.2 in/sec. 

 The blasting plan may not have been followed in respect to the protection of the 

underground mine seals; however, the estimated blasting vibrations, possibly 2.7 in/sec, 

were not high enough to damage the seals. 

Summary

 The blasting records did not identify the location of the blasts. Consequently, vibration 

estimates can only be made based on worst-case estimates. 

 Some of the PFs were high and could have resulted in excessive airblast, rock movement, 

and ground vibrations. 

 The blasting vibrations at the 2000 breakthrough do not appear to be high enough to have 

caused roof falls. However, the roof may have been weakened due to blasting induced 

64 
micro-fracturing. The extent of micro-fracturing and weakening cannot be quantified. 

Except at the breakthrough location, Triad’s drilling did not identify any excessive mine 

height, or rubble on the mine floor, which would be indicative of a roof fall. 

 The blasting vibrations may have been high enough immediately under the blasts to cause 

roof falls. However, if roof falls did occur, the Triad drilling indicates that they did not 

extent into the 2000 breakthrough area. 

 MCCC may not have complied with the blasting limits associated with blasting near the 

underground mine seals, but OSM’s review of the blasting levels indicates that the 

blasting vibrations were not high enough to damage the seals. 

3.5.4 Effects of Natural Seismic Activity: On October 8, 2000, at about 2:30 p.m., a roof fall 

occurred at the Mine Number 2 of Excel Mining LLC (Excel), underground mine (Permit 

Numbers 880-8005 and 880-8006). The mine is located about four miles from the MCCC 

impoundment. Reportedly, the Excel roof fall was about 350 feet long, 22 feet wide, and 8.5 feet 

in thickness. OSM examined whether the Excel roof fall may have triggered the 2000 

breakthrough or that an earthquake could have caused both the Excel roof fall and breakthrough 

(Appendix 12). 

KGS monitors earthquake and ground vibration activity from Clay City, Kentucky, station 

ROKY. The station is located about 78 miles west of the MCCC impoundment. The station also 

records vibrations from blasting at coal mines (mostly to the east and southeast of ROKY) and 

limestone quarries (both east and west of ROKY). 

Precise estimates of seismic energy at the MCCC site were not possible. However, based on the 

ROKY data, this study has made the following general observations on seismic activity in the 

region: 

 Seismic energy arriving at ROKY from September 25 to October 27, 2000, was generally 

light. 

 Considerable seismic activity occurred between 3:00 p.m. and 6:00 p.m. each day, 

Monday through Saturday, and was absent each Sunday. These times correlate well with 

blasting activity at the mines in eastern Kentucky. 

 An earthquake occurred on October 25, 2000, at about 6 a.m. It had a four-minute 

duration and contained higher amplitude vibrations than the regional blasting vibrations. 

 On October 8, 2000, at about 2:45 p.m., there was a minor seismic event, which is near 

the time of the roof fall at the Excel underground mine. The amplitude of the seismic 

event was much less than the earthquake and blasting vibrations. 

 There was no seismic activity leading up to and through the 2000 breakthrough after 7:00 

p.m. on October 10, 2000. Prior to 7:00 p.m., the seismic activity was consistent with the 

blasting activity at the mines. 

65 
Summary

 There was minor seismic activity near the time of the roof fall at the Excel mine; 

however, the activity was much less than earthquake and blasting vibrations. 

 There was not any seismic activity for the five-hour period prior to the 2000 

breakthrough. Prior to that five-hour period, only seismic activity consistent with 

blasting was identified. 

3.5.5 Seepage Barrier Stability: OSM performed a stability analysis of the seepage barrier at 

the 2000 breakthrough (Appendix 6). The analysis used both the designed and constructed 

outslopes of 2:1 and 3:1, respectively, and accounted for both consolidated and unconsolidated 

slurry for the foundation. It also assumed that the seepage barrier extends down to 

approximately 986 feet msl, which is also the approximate slurry elevation at the time of the 

1994 breakthrough. The assumption is based on: (1) the 2000 breakthrough is located at the rear 

of the impoundment and the seepage barrier was constructed about one year after the 1994 

breakthrough, and (2) the slurry added after the 1994 breakthrough probably did not have time to 

consolidate sufficiently to support the dumped spoil. For purposes of this analysis, OSM 

assumed that the constructed seepage barrier did not extend to the level of the Coalburg coal 

seam outcrop. 

 

The study determined that the seepage barrier had a safety factor of at least 1.1 (for the 3:1 

outslope and unconsolidated case) when the slurry level was at 986 feet msl and 1.8 with the 

slurry at 1,045 feet msl and the pool at 1,060 feet msl. The pool was at 1,060 feet msl at the time 

of the 2000 breakthrough. The failure zone for the 1.1 safety factor is shallow, and should not 

have adversely affected the structural stability of the seepage barrier. The most significant effect 

of this type of failure would have been to strip away the fine refuse coating on the surface, thus 

increasing the permeability of the barrier. The next lowest safety factor is 1.2 with the pool at 

1,000 feet msl. This failure would have extended into the slurry foundation and produced a 

noticeable head-scarp at about 1,040 feet msl. This condition was not noted on the weekly 

inspection reports or in the annual certifications. 

Summary

 Shallow sloughing of the seepage barrier may have occurred. 

 The review did not identify a high potential for structural instability, and the weekly 

inspection reports and annual certifications did not report any slides. 

3.5.6 Underground Mine Pillar Stability: OSM reviewed the stability of pillars at the 2000 

breakthrough (Appendix 13). The pillar stability calculations were performed for 20-foot by 25- 

foot pillars, 10 feet high, and 600 pound per square inch coal strength. At this location, the 

overburden was assumed to be 70 feet in order to represent the loading of the natural ground, 

seepage barrier, slurry, and water. Based on these calculations, OSM determined that the pillars 

66 
had a safety factor of at least 1.7, and thus, should be stable. This determination was confirmed 

by the Triad drilling, which did not find evidence of pillar failure. 

Summary

 The review indicates that the pillars adjacent to the 2000 breakthrough are stable. The 

Triad drilling did not find evidence of pillar failure. 

67 
BLANK PAGE

68 
4.0 PROBABLE BREAKTHROUGH MECHANISM 

To determine the probable cause of the 2000 breakthrough, OSM considered four potential 

failure mechanisms. These are addressed in Section 3.1 and are summarized below: 

1. Failure of sealed underground mine openings

2. Breakthrough at an unsealed underground mine opening

3. Breakthrough at coal barriers

4. Breakthrough at strata overlying the coal seam

4.1 Failure of Sealed Underground Mine Openings 

This failure mechanism relates to mine openings that have been sealed with rock, soil, or other 

material. Mine openings are entries or borings within the impoundment area that connect the 

underground mine with the surface. OSM’s review did not find any evidence of mine openings 

at the 2000 breakthrough. 

The impoundment is bounded by the MCCC 1-C underground mine on all sides except the valley 

of Big Branch south-southeast of the embankment (Figure 2 [Page 4]). Two areas of the 

underground mine, mined during 1981 and 1982, abut the impoundment to the north and south, 

and at some points extend short distances under the impoundment. As addressed in Section 

3.3.2.5, OSM’s review of the underground mine maps did not find any evidence that any of the 

underground mine entries extended to the surface at the 2000 breakthrough. Further, as 

addressed in Section 3.5.1.2, the Triad drilling at the breakthrough did not identify any entries 

that extended to the surface. 

4.2 Breakthrough at an Unsealed Underground Mine Opening 

This failure mechanism relates to mine openings that have not been sealed. As addressed in 

Section 4.1, OSM did not identify any openings at the 2000 breakthrough. 

4.3 Breakthrough at Coal Barriers 

This failure mechanism relates to the failure of coal barriers. The barriers may be: (1) 

underground mine outcrop barriers within the impoundment area, (2) coal barriers between 

surface mines within the impoundment area and adjacent underground mines, or (3) coal barriers 

between different underground mines where at least one of the mines has surface openings 

within the impoundment area. OSM concludes that the mechanism for the 2000 breakthrough 

was primarily an outcrop barrier failure. 

 

OSM concludes that the breakthrough was caused by seepage and piping through the outcrop 

barrier at the southwest corner of the 50-foot long, dead-end entry. The seepage from the 

impoundment may have been through: (1) natural fractures that connected with the entry, (2) 

69 
natural fractures exposed by a roof fall, (3) fractures created by a roof fall, and/or (4) weathered 

coal and overburden. The various conditions related to these conclusions are addressed below. 

4.3.1 Barrier size and composition: The MCCC underground mine at the 2000 breakthrough 

was separated from the impoundment by an outcrop barrier. The outcrop barrier, as addressed in 

Section 3.5.1.3, was composed of colluvium, sandstone, shale, and coal. As addressed in 

Sections 2.1.3 and 2.1.5, there are no indications that the outcrop barrier was disturbed by 

surface mines or small underground mines at the breakthrough. OSM’s review of maps and 

photographs found that an access road had been constructed over the outcrop barrier but was 

unable to determine if the road was cut into the outcrop barrier or was built on fill material. 

OSM has not been able to determine whether the road contributed to the breakthrough. As 

addressed in Section 3.3.2.5, MCCC did not conduct a geotechnical investigation to determine 

the nature and width of the outcrop barrier. 

As addressed in Section 3.5.1.3, at the end of the mine entry where the 2000 breakthrough 

occurred, the overburden, based on vertical measurements from Figure 7 [Page 55], was 

composed of about 14 feet of sandstone and 11 feet of colluvium. (Note: MSHA has 

characterized this distance by a diagonal measurement of 27 feet at the end of the mine entry. 

MSHA’s measurement was made along Triad Profile D-D [see Inset Figure 4 on Page 18] while 

OSM’s measurement was made along Triad Profile A-A, Figure 7 [Page 55].) The upper half of 

the sandstone overlying the entry was weathered. At the end of the 10- to 12-foot section of 

“missing coal” (Figure 7 [Page 55]), the overburden is composed of only about four feet of 

weathered sandstone and 15 feet of colluvium. Prior to the breakthrough, the weathered 

sandstone may have been underlain by one to two feet of shale. 

The full thickness of the Coalburg coal seam exists for only about 15 feet beyond the mine limit 

as mapped, and then it thins to zero feet thick at about 33 feet from the end of the mine (Figures 

6 and 7 [Pages 53 and 55]). The Triad drill logs did not identify coal in the remaining portion of

the 70-foot wide outcrop barrier. This coal is presumed to be in a weathered condition, and it 

may have been transported downslope due to hillside creep. 

4.3.2 Subsidence potential: As addressed in Section 3.5.1.1, the 2000 breakthrough occurred at 

the southwest corner of the 50-foot long, dead-end entry at Line #1 as illustrated in Figures 2, 4, 

and 6 (Pages 4, 18, and 53). A cross-section of the failure area is shown on Figure 4 (Page 18). 

Cross-section A-A at Line #1 from the Triad report is shown on Figure 7 (Page 55). OSM’s 

assessment of the potential that subsidence was a factor in the breakthrough is as follows. 

The roof condition along the centerline of the mapped entry (Figure 7 [Page 55]) indicates that 

the breakthrough was not the result of a massive roof fall. The figure shows that the roof along 

the centerline at the end of the entry is still standing, proving that no massive roof fall occurred. 

 

Finally, a localized roof fall could have occurred at the southwest corner of the entry as mapped. 

The Figure 4 (Page 18), Triad Profile D-D inset, shows that the sandstone overhangs the entry 

and is largely intact. Therefore, if a localized roof fall did occur, it did not extend vertically 

upward through the overlying sandstone. However, the roof fall could have intercepted natural 

fractures. 

70 
4.3.3 Seepage barrier permeability: As addressed in Sections 3.3.2.1 and 3.5.1.4, the seepage 

barrier was permeable and saturated near the outcrop barrier. While the colluvial portion of the 

outcrop barrier may not have been as permeable as the seepage barrier, the colluvium was also 

saturated. As addressed in Section 3.3.2.1, MCCC did not discharge slurry along the seepage 

barrier as required to inhibit seepage. The permeable and saturated nature of the colluvium and 

seepage barrier did not prevent seepage into the underground mine. Increased seepage may have 

started as early as April 1998. Starting in September 1999, seepage increased significantly 

(Section 3.5.2 and Figure 9 [Page 62]). OSM’s review found that the increase was likely due to 

leakage from the impoundment into the underground mine and was an indicator of the impending 

breakthrough. 

4.3.4 Seepage and piping: OSM believes that seepage into the underground mine removed fine 

soil material from the outcrop barrier as well as the seepage barrier. The seepage may have also 

caused additional weathering and erosion of the outcrop barrier. This process of internal erosion 

is known as “piping.” OSM believes that piping caused the breakthrough. 

Starting in September 1999, there was a significant increase in the rate of seepage into the 

underground mine (Section 3.5.2). The seepage may have exceeded 500 gallons per minute. 

This seepage may have occurred through the coal seam, the interface between the coal seam and 

the shale, the interface between the shale and sandstone, natural fractures, and roof-fall related 

fractures. Seepage and piping along the interfaces may have removed the support under the 

overlying sandstone causing it to settle and develop open fractures. This would have allowed 

increased seepage through the seepage barrier and colluvium with a resulting increase in piping. 

The piping and erosion would have created increasingly larger voids or cavities in the outcrop 

barrier and seepage barrier. At the time of the failure, the cavities may have extended through, 

or almost through, the seepage barrier itself creating a direct connection between the 

underground mine and the slurry impoundment. 

4.3.5 Bridging and plugging: As addressed in Section 3.3.2.1, large rocks were deposited at 

the base of the seepage barrier during construction due to gravity segregation. Initially, the 

larger rocks may have bridged over the cavities created by the piping and erosion. However, 

over a period of time, these rocks would not be able to permanently bridge the cavities and 

ultimately would collapse, allowing the slurry to rapidly discharge into the underground mine. 

As addressed in Section 3.5, the seepage barrier failed to plug the breakthrough, which was a 

stated purpose of the sealing plan. 

4.3.6 Other factors: OSM reviewed several other factors to determine if they contributed to the 

breakthrough, including precipitation (Section 3.5.2), blasting (Section 3.5.3), seismic activity 

(Section 3.5.4), seepage barrier stability (Section 3.5.5), and underground mine pillar stability 

(Section 3.5.6). OSM concluded that the breakthrough was not related to these factors. 

4.4 Breakthrough at Strata Overlying the Coal Seam 

This failure mechanism relates to mine roof falls that extend to the surface or subsidence induced 

by pillar failure or pillar extraction. As addressed in Section 4.3.2, Subsidence Potential, OSM’s 

71 
review indicates that the 2000 breakthrough may, in part, be related to a roof fall. OSM’s review 

indicates that the pillars are stable (Section 3.5.6), and that the pillars were not extracted (Section 

3.5.1.2). 

72 
5.0 CONCLUSIONS AND RECOMMENDATIONS

OSM’s study of the breakthrough at the Big Branch slurry impoundment, conducted by a team of 

engineers, geologists, and hydrologists, was performed in cooperation with MSHA, DSMRE, 

and DMM. OSM used information and data relating to: 

 General history of the underground mine and impoundment. 

 DSMRE permit files and MSHA-approved plans. 

 Investigations of the 1994 breakthrough. 

 Remedial measures to prevent breakthroughs after 1994. 

 MCCC’s EAP. 

 MSHA’s investigation of the 2000 breakthrough. 

Based on its own independent technical evaluation, OSM is in agreement with the findings and 

enforcement actions taken to date by DSMRE and MSHA. The investigations by MSHA and 

DSMRE were primarily to determine if MCCC had violated the terms and conditions of the 

permit and plan approvals. MSHA also reported the probable breakthrough mechanism. The 

scope of OSM’s review included the same issues addressed by DSMRE and MSHA enforcement 

actions, as well as the probable breakthrough mechanism. In addition, OSM’s review included 

an evaluation of the sealing plan approval by DSMRE and certifications and actions taken to 

protect the public. 

The following conclusions and recommendations are based upon OSM’s investigation of the 

factors contributing to the MCCC 2000 breakthrough. Although these conclusions are specific to 

this investigation, the recommendations are broadly applicable to the prevention of 

breakthroughs at other impoundments. OSM suggests that the recommendations be used in 

conjunction with the Criteria for Evaluating the Potential for Impoundment Leaks into 

Underground Mines (Existing and Proposed Impoundments) released by OSM in July 2001. The 

conclusions are grouped by the issues OSM agrees with MSHA and DSMRE to aid the reader to 

better understand the actions of the various agencies. 

Conclusions: 

In agreement with MSHA, 

 OSM concludes that the breakthrough was caused by seepage and piping through the 

outcrop barrier at the southwest corner of the 50-foot long, dead-end entry. 

 OSM concludes that MCCC failed to analyze and report a forewarning of the 

impending breakthrough--the significant increase of drainage from the South Mains 

Portal pond beginning in September 1999. 

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 OSM concludes that MCCC did not submit an as-built certification for the 

constructed bulkheads. 

In agreement with DSMRE, 

 OSM concludes that MCCC submitted modifications to the 1994 Impoundment 

Sealing Plan to MSHA but not to DSMRE for approval. 

In agreement with both MSHA and DSMRE, 

 OSM concludes, after comparing the Triad drilling information with the 1994 

Impoundment Sealing Plan, that (a) the width of the Coalburg coal seam outcrop 

barrier (the horizontal distance from the underground mine to the surface) is correctly 

projected in the plan, but (b) the plan incorrectly indicates that the entire Coalburg 

coal seam outcrop barrier is composed of solid coal and rock. 

 OSM concludes that MCCC did not conduct any geotechnical investigation to 

confirm the width or to determine the composition of the Coalburg coal seam

outcrop barrier either before or after the 1994 breakthrough.

 OSM concludes that MCCC did not construct the seepage barrier in accordance with 

the 1994 Impoundment Sealing Plan as approved by MSHA and DSMRE. 

Additional OSM Findings: 

These issues may have been considered by DSMRE and MSHA, but were not addressed by their 

actions and reports.

 OSM cannot conclude definitively whether the 1994 Impoundment Sealing Plan 

would have prevented a breakthrough because the seepage barrier was not 

constructed in accordance with the plan. However, OSM found that the approved 

sealing plan did not contain a complete analysis of the breakthrough mechanisms and 

the associated preventative measures. 

 OSM concludes that MCCC did not submit an as-built stability analysis, for 

certification purposes, for the constructed seepage barrier.

 OSM concludes that the 1994 Impoundment Sealing Plan (breakthrough prevention 

plan) was approved as a minor modification by DSMRE; and therefore, public notice 

was not required. 

 OSM concludes that the EAP submitted to MSHA addressed the consequences of an 

embankment failure, but did not address the consequences of an impoundment 

breakthrough. 

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Recommendations: 

 OSM recommends that adequate geotechnical investigations be conducted to verify 

the location of the underground mine and the composition of the outcrop barrier and 

overburden for all existing and proposed impoundments in close proximity to either 

an active or abandoned underground mine. 

 OSM recommends that plans designed to prevent breakthroughs at slurry 

impoundments be based on the most conservative engineering design standards and 

be supported by the best site-specific, scientific data available, commensurate with 

the level of risk posed by the impoundment. 

 OSM recommends that the breakthrough prevention plans for any new impoundments 

or modifications to existing impoundments identify the critical phases of construction 

and that the registered professional engineer who designed the plan also inspect and 

certify the critical phases of construction with as-built drawings as appropriate. 

 OSM recommends that the breakthrough prevention plans include rigorous 

hydrogeologic monitoring requirements designed to provide a forewarning of any 

impending breakthrough. 

 OSM recommends that revisions to permits concerning breakthrough prevention be 

considered major modifications if the breakthroughs would adversely affect the 

public; and therefore, be subject to public notice and comment. 

 OSM recommends that the SRAs assess coordination procedures with MSHA for 

review and approval of impoundments to ensure proper fulfillment of respective 

statutory responsibilities. 

 Finally, OSM should consider developing national standards for EAPs, through 

rulemaking, which consider the consequences of an impoundment breakthrough. 

 

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76 
ACRONYMNS 

ARCC - Appalachian Regional Coordinating Center 

Blackburn - Blackburn Contracting, Inc. 

cm/sec - centimeter per second 

DES - Disaster and Emergency Services 

DMM - Department of Mines and Minerals 

DOW - Division of Water 

DSMRE - Department for Surface Mining Reclamation and Enforcement 

EAP - Emergency Action Plan 

EPA - Environmental Protection Agency 

Esmer - Esmer & Associates, Inc. 

Excel Mining LLC - Excel 

GAI - Geo/Environmental Associates, Inc. 

IC - Information Circular, U.S. Bureau of Mines 

IDCO - Imminent Danger Cessation Order 

IFLOWS - Integrated Flood Observing and Warning System

in/sec - inches per second 

KAR - Kentucky Administrative Regulations 

KGS - Kentucky Geological Survey 

KPDES - Kentucky Pollutant Discharge Elimination System

MCCC - Martin County Coal Corporation 

Mine Act - Federal Mine Safety and Health Act of 1977 

Minor Permit Revision No. 5 - the permit revision 

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MRP - Mining and Reclamation Plan 

MSHA - Mine Safety and Health Administration 

msl - mean sea level 

NC - Non-Compliance 

NCP - National Contingency Plan 

NRC - National Response Center 

NWS - National Weather Service 

Ogden - Ogden Environmental and Energy Services 

OSC - On Scene Coordinator 

OSM - Office of Surface Mining 

PF - powder factor 

SMCRA - Surface Mining Control and Reclamation Act of 1977 

SRA - State Regulatory Authority 

Summit - Summit Engineering, Inc. 

Triad - Triad Engineering, Inc. 

TSS - total suspended solids 

Unified Command - Unified Incident Command Organization 

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BIBLIOGRAPHY

Babcock, C. and Hooker, B., Results of Research to Develop Guidelines for Mining Near

Surface and Underground Bodies of Water, U.S. Bureau of Mines Information Circular 

8741, 1977, p. 4. 

Hawkins, J.W., and Aljoe, W.W., Hydrologic Characteristics of a Surface Mine Spoil Aquifer, 

U.S. Bureau of Mines, Proceedings from Second International Conference on the 

Abatement of Acidic Drainage, 1991, pp. 47-68. 

Peng, S.S., Coal Mine Ground Control, John Wiley & Sons, Inc., 1978, p. 74.

 

Skelly and Loy, Development of New Design Concepts for Construction of Valley Fills, U.S. 

Bureau of Mines, Contract Number J0177063, 1978, p. 77.

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