DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
OFFICE OF THE ADMINISTRATOR
COAL MINE SAFETY AND HEALTH
REPORT OF INVESTIGATION
UNDERGROUND COAL MINE BURST
(RIB FALL)
C-2 MINE - I.D. NO. 15-07201
HARLAN CUMBERLAND COAL COMPANY
DIONE, HARLAN COUNTY, KENTUCKY
NOVEMBER 20, 1996
by
Billy G. Foutch
Supervisory Coal Mine Safety and Health Specialist, Norton, VA
Charles H. Grace
Conference and Litigation Representative, Barbourville, KY
Curtiss Vance
Coal Mine Safety and Health Inspector, Logan, WV
Michael A. Evanto
Pittsburgh Safety and Health Technology Center
Geologist, Pittsburgh, PA
George J. Karabin, Jr.
Pittsburgh Safety and Health Technology Center
Supervisory Civil Engineer, Pittsburgh, PA
Danny Harmon
Supervisory Coal Mine Safety and Health Specialist
(Roof Control), Pikeville, KY
Originating Office - Mine Safety and Health Administration
Office of the Administrator - Coal Mine Safety and Health
4015 Wilson Boulevard, Arlington, Virginia 22203
Marvin W. Nichols, Jr., Administrator
Release Date: April 14, 1997
OVERVIEW
Abstract of Coal Burst
At approximately 2:08 p.m. on November 20, 1996, a coal burst occurred on the 005-0 working section located in the Second Left panel off Nine Right off of the No. 3 East Main entries of Harlan Cumberland Coal Company's, C-2 Mine. Nine miners were working on the section at the time of the burst. The coal burst resulted in the deaths of two of the miners located on the section. Four other miners sustained varying degrees of injury.
As room pillar No.1 was mined, much of its load was released and transferred to the already highly stressed adjacent pillars. This sudden pressure increase on the adjacent pillars was sufficient to cause failure of coal near or into the core of these pillars, and resulted in the burst.
The coal ribs were not controlled to protect persons from the hazards of a coal burst in the three rooms off Second Left (MMU 005-0), an active working section where persons worked and traveled. The coal burst damaged the ribs of all nine pillars in the rooms, blowing in excess of 1,500 tons of coal into the room entries and crosscuts.
Background
The Harlan Cumberland Coal Company, C-2 Mine located near Dione, Harlan County, Kentucky, began operation on or about October 1, 1980. The mine is developed and serviced through three portals consisting of drift openings into the Creech Coal Seam. The coal seam ranges in thickness from 42 to 96 inches.
The principal management officers of the mine at the time of the coal burst were:
Joe T. Bennett.........................................President
C. V. Bennett III.....................................Vice-President
Catherine Bennett McCue.......................Secretary
Clyde V. Bennett....................................General Manager
The coal mineral rights are owned by Catherine Bennett McCue, Karen Bennett Loving, Joseph T. Bennett, Darby Bennett, and the Cornett-Lewis Estate and are leased to Harlan Cumberland Coal Company. Owners of the surface area are Ark Land Company and Nally & Hamilton.
The mine employs a total of 55 miners and produces coal two shifts per day, six days per week. Equipment maintenance is performed on a separate nonproducing shift.
The mine is a two unit mine with one advancing and one retreating unit. The advancing 004-0 section utilizes a five entry system. The retreating 005-0 section utilizes a five entry system and develops rooms to the right of the panel entries. Room pillars are extracted first, followed by the adjacent entry pillars.
At the time of the coal burst, eight miners and a foreman were working underground on the 005-0 working section. The section had completed development of a set of three rooms and was in the process of extracting the No. 1 room pillar.
The mining system on the 005-0 working section utilized a Joy 14CM Continuous Mining Machine, two Joy 10SC Shuttle Cars, an Elkhorn AR-95 Battery-Powered Scoop, and a Fletcher Twin Boom Roof Bolting Machine with "T-Bar" Automated Temporary Roof Support System (ATRS).
A MSHA regular Safety and Health inspection (AAA) was ongoing at the time of the accident. The previous inspection (AAA) was completed on September 24, 1996.
THE COAL BURST
On Wednesday, November 20, 1996 at approximately 5:45 a.m., the 005-0 working section's second (day) shift crew, consisting of eight miners traveled underground accompanied by Darrell Lewis, foreman. Arriving on the section at approximately 6:25 a.m., they were met by Ernie Boggs, maintenance foreman, who had conducted the pre-shift examination earlier that morning. Boggs reported to Lewis that nothing unusual had been found during the course of his examination.
Darrell Lewis proceeded to issue instructions to the crew members and coal production began at approximately 6:30 a.m.
Production commenced by advancing the left crosscut in the No. 2 room. Successive cuts were then advanced without incident, in all three rooms, until the room entries and crosscuts were connected to the gob.
After completing these connections the continuous mining machine was moved to the No. 1 room pillar to take the initial cut, beginning pillar extraction. The initial cut was advanced into the No. 1 pillar approximately 15 feet deep when, at approximately 2:08 p.m., a coal burst occurred, claiming the lives of Mark Skidmore and, subsequently, that of Randy Lewis, both roof bolting machine operators. Four other miners sustained various degrees of injury. Injured were: Darrell Lewis; John Carroll, scoop operator/roof bolting machine operator; and, Jim Carr and David Harris, both continuous mining machine operators.
The force of the coal burst was felt by other employees located on the 005-0 working section and was detected by seismic stations of the University of Kentucky, at four locations, averaging a magnitude of 2.7 on the Richter Scale. However, no persons outside the immediate area of the coal burst were adversely affected. No other significant seismic events were recorded either immediately prior to or after the accident.
RECOVERY OPERATIONS
At approximately 2:25 p.m., Kenneth Fee, MSHA, Harlan, Kentucky Field Office Supervisor was notified of the accident by Clyde V. Bennett of Harlan Cumberland Coal Company. Bennett reported that a "bump" had occurred on the 9 Right unit at the C-2 mine and that at least one miner was unaccounted for.
Fee immediately dispatched inspectors from the Harlan Field Office, accompanied by Robert W. Rhea, MSHA Field Office Supervisor, to the mine site. Fee next notified John M. Pyles, Assistant District Manager, of the accident.
MSHA inspectors arrived at the site at approximately 2:55 p.m. Upon their arrival, the inspectors were met by state inspectors led by Ronnie Hampton of the Kentucky Department of Mines and Minerals and Johnny Smith, outside person, for the C-2 mine. Smith briefed Rhea, essentially providing the same information as Bennett had provided earlier to Fee. Smith identified the unaccounted-for miner as Mark Skidmore, Roof Bolting Machine Operator.
Rhea and Hampton assembled a recovery team consisting of MSHA and state inspectors and Eddie Sargent, Safety Director for Harlan Cumberland Coal Company, who had just arrived at the mine. The team then entered the mine while Rhea remained on the surface to coordinate recovery efforts. At that time, Matthew Coots, 004-0 Section Foreman, called to the surface and informed Rhea that two of the injured miners were en route to the surface and that Skidmore remained unaccounted for. Rhea continued to coordinate recovery efforts until the arrival of John Pyles at 4:30 p.m. Pyles was accompanied by Charles Grace, MSHA Conference and Litigation Representative. Coordination of recovery efforts were turned over to Pyles as the senior MSHA official on site. Rhea then traveled underground to assist in recovery efforts.
The recovery team arrived on the 005-0 working section where they encountered Ron Painter, shuttle car operator, at the 005-0 section feeder. Coots and Louis Blevins, Superintendent, assisted by six other miners, were in the process of moving the coal, rock, and debris which resulted from the burst. Additional roof support material, including cribbing, was then brought up to that position. Larry Bush, Federal Inspector, then proceeded to re-establish ventilation to the area where ventilation controls (curtains) in the face area had been dislodged by the burst. The recovery team proceeded steadily, installing roof support and removing the loose coal and rock in the area of Skidmore's last known location.
Skidmore's body was discovered at approximately 9:45 p.m., recovered, and was transported to the surface by battery powered personnel carrier, arriving at the portal at approximately 10:30 p.m. Skidmore was formally pronounced dead by Deputy Harlan County Coroner, Gerald Scott at 10:45 p.m.
INVESTIGATION OF THE COAL BURST
MSHA and the Kentucky Department of Mines and Minerals (KDMM) cooperated to conduct a joint investigation. Billy G. Foutch was appointed as leader of MSHA's investigation team. The primary focus of the investigation was to determine the cause(s) and extent of the burst and to assess the nature of geologic conditions in the area.
MSHA personnel from the Harlan and Barbourville, Kentucky offices provided information in regard to mine conditions, practices, and plan requirements. A pre-investigation conference and briefing was held at MSHA's Harlan Field Office on November 21, 1996. During this conference, mine and accident information was principally provided by Joseph W. Pavlovich, MSHA District Manager, and by John M. Pyles, to the joint investigation team and Kathy Snyder, representing MSHA's Office Information and Public Affairs. The C-2 mine employees did not designate a representative of the miners to participate in the investigation.
The on-site investigation began on November 21, 1996. On the first day of the investigation, mine records were examined in order to determine pre-existing conditions and practices. The underground examination of the accident scene was delayed due to ventilation problems and the presence of methane discovered earlier by inspectors of MSHA's Harlan Field Office and concerns for safety of the investigation team.
The next morning, on November 22, 1996, with the ventilation problems corrected and with methane and oxygen at acceptable levels, the joint investigation team entered the mine accompanied by company personnel. The accident investigation was organized with personnel assigned: to map the accident area; to evaluate the roof control system and conditions; to assess geologic conditions; to determine the extent and magnitude of the coal burst; and to photograph and collect information. In addition, roof conditions and roof control practices in other areas of the mine were evaluated in order to determine any correlation to similar conditions and practices which may have existed on the 005-0 working section prior to the accident. The 005-0 section ground conditions continued to deteriorate after the accident and the scene was essentially found covered by coal, rock, and debris to the extent a full assessment and examination of the area was impractical. The investigative assignments were completed within several hours, and the investigators exited the
Related Fatal Alert Bulletine investigation, MSHA and KDMM conducted interviews of persons with knowledge of the facts and circumstances surrounding the coal burst. Interviews were conducted with individuals between December 2, 1996 and December 13, 1996. Twenty-four interviews were conducted at the MSHA Field Office in Harlan, Kentucky, and one interview was conducted at the home of a seriously injured miner. The hourly employees did not designate personal representatives during the interviews. However, all officials and agents of Harlan Cumberland Coal Company, including the mine engineer and survey crew personnel, were represented by attorneys.
DISCUSSION
Mine Development and Roof Control History
The C-2 mine was developed from the surface in 1980. The mine is served by three portals consisting of drift openings into the Creech coal seam. The present workings consist of: two active working sections, mains, panels, and an extensive gob consisting of pillared-out workings and bleeder entries. The investigators studied the history of roof control incidents at the C-2 mine. Following is a discussion of four significant events that occurred prior to November 20, 1996.
On January 11, 1990, a non-injury coal burst occurred on the Second Right off No. 2 East Mains during pillar recovery operations. The mine roof consisted of up to 10 feet of firm, sandy shale followed by 10 feet or more of firm sandstone. The mine floor was composed of firm shale that had heaved substantially at some locations. Mining height was about 6.7 feet and the total overburden in the area was approximately 1300 feet. Coal pillars across the section had generally been developed to dimensions of approximately 40 feet by 60 feet. The burst did not result in injury or damage to equipment. However, the burst caused extensive damage to a large pillar (60 feet by roughly 175 feet in size) located adjacent to a block being split and between one of the section's panel entries and the old workings of the East Main headings. Moderate damage was sustained by another adjacent pillar. Subsequent to the burst mining operations ceased at this location and mining resumed approximately 300 feet outby the affected area. The burst was investigated by MSHA and was found to have occurred as a direct result of utilizing faulty mining methods that created a coal pillar with dimensions not compatible with the effective control of coal bursts.
In July, 1994, a "squeeze" condition occurred during pillaring on the 8 Right section. The five entry panel had been developed on 80-foot by 80-foot centers. Sets of five rooms were driven to the right, on 80-foot by 65- to 75-foot centers, through a 340-foot wide barrier pillar separating the 8 Right and 7 Right sections. After recovering approximately eight rows of blocks the squeeze occurred, primarily in the newly developed rooms outby the pillar line. Observations by MSHA's Pittsburgh Safety and Health Technology Center (PSHTC) and District 7 personnel revealed that the floor had heaved extensively with heavy pillar sloughing, and several roof falls were noted toward the gob. Mining height in the area was about six feet and overburden had increased from less than 1,000 feet near the southern end of 8 Right to over 1,400 feet at the face. A borehole, located about 500 feet from the pillar line, disclosed the presence of massive sandstone 22 feet above and six feet below the Creech seam, and indicated the existence of a coal seam (six inches thick) roughly six inches below the shale mine floor. This combination of geological conditions may have contributed to the squeeze. As a result of this evaluation, PSHTC made recommendations including the design of barrier pillars and the reduction of entry and crosscut widths to enhance pillar line conditions during the retreat mining of the 9 Right and the proposed 10 Right sections.
Subsequent to the receipt of MSHA's Technical Evaluation, on November 10, 1994, MSHA's District 7 Manager, Joseph W. Pavlovich, forwarded a letter to the mine operator. The letter instructed the operator that before pillar mining in 8 Right was resumed following the "squeeze", that a revision to the approved roof control plan would be necessary. The proposed revision was to address MSHA's concerns as related in PSHTC's Technical Evaluation of November 7, 1994, which was included as an attachment to the letter.
On January 3, 1995, the mine operator responded to the District Manager's request, providing a written plan in regard to pillaring on the 8 Right Section. An investigation of the operator's proposal was made by representatives of MSHA's Harlan Field and District Offices.
On January 20, 1995, the District Manager denied approval of the operator's proposal stating that the stress encountered would not likely be relieved by mining the 8 Right pillars. Failing to leave a barrier between 8 Right and 9 Right would continue to cause overriding stress into the future panels. The operator was asked to provide additional and clarifying information and to resubmit the proposal.
During this period, the mine operator engaged the services of three mining/roof control consultants; Dr. Kot F. Unrug of Lexington, Kentucky, Henry L. Kiser of Abingdon, Virginia, and Dr. David A. Newman of Appalachian Mining and Engineering, Inc. of Lexington, Kentucky.
Two of the three consultants recommended leaving a barrier pillar or additional pillars between 8 Right and 9 Right, consistent with MSHA's previous recommendation. No further pillaring was performed on 8 Right and the operator developed 9 Right, generally incorporating the consultants' recommendations into the pillar and barrier design. A barrier pillar approximately 330 feet in width was left between the 8 Right and 9 Right panels.
During the period of May through July, 1996, a severe loading condition was experienced on the 1st Left off 3 East Mains resulting in the abandonment of 29 pillars that had been planned to be recovered. The 1st Left section was developed on 80-foot by 80-foot centers as were panels and rooms to the right. After retreating pillars successfully for about 2,200 feet, deteriorating roof conditions, including numerous roof falls, were experienced in the 1st Left and adjacent panels. While the specific roof and floor composition is not known, mining height averaged six feet, and cover steadily increased from less than 300 feet at the northern end of the 1st Left off 3 East Mains panel to over 1,400 feet at the center of the affected area. However, no problems were reported during pillar extraction in outby areas where cover ranged from 1,380 feet to 1,200 feet.
In September of 1996, an event occurred during pillar recovery on the 1st Left off 9 Right Section that caused that section to be abandoned. The event has been described by various mine personnel as a "pressure point" resulting in unstable roof, a "squeeze" or a "bump". The area was primarily developed on 80-foot by 80-foot centers (60-foot by 60-foot pillars). However, the pillars being extracted ranged from 50-foot by 60-foot to 60-foot by 60-foot in size. In addition, several pillars with dimensions of 40 feet by 60 feet were located just outby the blocks being mined when the event occurred. Reportedly, the event occurred during the initial cut of a pillar (three pillars had been cut in this manner) that affected it and an adjacent block. This resulted in roof/floor convergence that temporarily wedged a shuttle car in place and caused the subsequent occurrence of a number of roof falls in the area. From a borehole, located about 600 feet from the pillar line, the immediate roof consists of 14 feet of dark gray shale that is overlain by a 24-foot thick layer of massive sandstone. The mine floor is composed of 1 foot of firm shale followed by 32 feet of massive sandstone. Mining height averaged 6.1 feet in the area and cover varied from about 600 feet at the southern end of the 1st Left off 9 Right panel to nearly 1,100 feet at the face. Following the event, mining ceased and the section was abandoned.
Roof Control Plan
The Roof Control Plan which was in effect at the time of the accident was originally approved on June 2, 1995. The plan, as was further revised on December 6, 1995, provided for full overhead support in all advancing roof spans. Roof support on the retreating 005-0 section is maintained with full overhead support in the initial cuts of the pillar splits and posts in the remaining split and lift cuts.
The roof control plan stipulated a maximum entry width of 20 feet, developed with a minimum distance of 60 feet between the centers of entries and crosscuts and 50 feet between the centers of rooms and crosscuts. The minimum pillar size for pillar extraction is 40 feet by 40 feet.
Rods, fully grouted with polyester resin are used on the advancing sections. The minimum length of the rods is 42 inches with installation on 48-inch centers. Mechanically anchored, tensioned roof bolts are used on the retreating 005-0 section. The minimum length of the bolts is 30 inches installed on 48- inch centers.
Mining Method and Roof Control (005-0 Section)
The 005-0 section (2nd Left off 9 Right) had been advanced as a five entry panel on 80-foot by 80-foot centers to the property boundary leaving minimum size coal pillars of 60-foot by 60-foot in dimension. Entries were mined approximately 19 feet wide and a barrier pillar, 230 feet in width, separated the panel from the previously mined 1st Left panel off 9 Right. The roof was supported with 4-foot long fully grouted bolts installed on a 4-foot by 4-foot pattern. Steel straps and longer bolts were used as supplements where conditions warrant. The section was in the process of retreating, recovering panel pillars. Mining on the section also included the development of rooms into the adjacent barrier pillar and the recovery of the room pillars. The burst occurred during the recovery of the room pillars.
The normal retreat mining method used on the 005-0 section was to develop five rooms on 80-foot centers through the barrier pillar, with two rows of crosscuts turned on 90-foot and 80-foot centers, respectively. Two rows of four pillars (in the developed barrier) were then extracted from left to right, followed by four rows of five pillars (four panel pillars and the remaining barrier pillar) recovered from right to left.
At the accident location, the method of developing rooms in the barrier pillar was changed from a five-room system to a three-room system. According to mine personnel, pressure on the blocks had been increasing and it was hoped that by driving fewer rooms, the pillars could be mined faster and more complete caving would occur and relieve the pressure. It should be noted that cover had increased to about 1,400 feet in this area and the extent of the frontal gob had grown to nearly 1,000 feet. The side gob, however, had been reduced to about 130 feet adjacent to the face due to the boundary of the mine property.
General Mine Geology
The mine is located in the Creech coal seam. Mining height varies from 42 inches to 96 inches. The immediate roof normally consists of 10 feet to 18 feet of firm, sandy shale and the main roof consists of 10 feet or more of firm sandstone. The remaining overburden contains roughly 52 percent sandstone (including a number of massive layers), 42 percent shale, four percent siltstone and 2 percent coal. The mine floor is composed of zero to three feet of shale followed by a massive sandstone layer, usually in excess of 30 feet thick.
A number of coal seams exist above and below the Creech seam, including the Harlan seam (about 375 feet below), the Darby seam (roughly 150 feet below) and the High Splint seam (approximately 1,000 feet above). Mining in the Harlan seam has been confined to areas east of the 7 Right section and north of the C-2 property. The Darby seam has been mined under the western extent of the C-2 property and east of the 7 Right section. The High Splint seam has also been extensively mined, but like the Harlan and Darby seams, no mining over the active works of the C-2 mine is known.
Overburden above the C-2 mine varies in the mountainous terrain from under 100 feet near the drift mouth to over 1,600 feet at the deepest point under Black mountain.
General Geology of the 005-0 Section
The immediate roof on the 005-0 section is composed of roughly 14 feet of firm dark grey shale as learned from a borehole located 500 feet from the face. That same borehole indicates the presence of a 36.8-foot thick massive sandstone layer and a 23.8-foot thick bedded sandstone formation immediately above the shale roof. Additional sandstone layers 18.2, 7.1, 33.3, and 21.9 foot thick exist within the next 150 feet of overburden. The mine floor consists of about 1 foot of firm shale followed by 31.6 feet of massive sandstone.
Cover over the 005-0 section increased from less than 850 feet at the eastern end of the panel to over 1,420 feet at the accident site. Mining height averaged about 6.7 feet in the vicinity of the accident site.
Ground Conditions On the 005-0 Section Prior to the Burst
Prior to the accident, conditions on the 005-0 section were thought to be "normal" by the section crew. The gob was tight around the perimeter of the section, the roof appeared stable. Test holes drilled earlier in the shift and the previous shift reportedly disclosed no cracks. According to the miners interviewed, pillar sloughing was pronounced in some areas but no red dust or signs of abnormal pressure were evident. However, several miners did note that the roof bumped (cracked) several times while turning the last crosscut in the No. 1 room and that considerable roof bumping occurred in the vicinity of the No. 1 room pillar as the initial cut began.
Description and Extent of the Burst
The coal burst on the 005-0 section occurred as the initial cut was advanced about 15 feet into the No. 1 pillar of the No. 1 room. The burst resulted in damage to the ribs of all nine room pillars, over 1,500 tons of coal blown into the rooms and room crosscuts, injuries to four miners, and the death of two miners.
The extent of the burst is illustrated in the sketch labeled "Accident Site Details - 005-0 Section" included in the front of this report. The sketch was compiled from observations made on November 22, 1996 and interviews with eyewitnesses to the event. The No's. 2 and 3 pillars displayed the most damage as the gob side ribs of these blocks (diagonally) were largely destroyed. Blown coal was roofed at the back end of the No. 2 room and was three to four feet deep inby the last open crosscut in the No's. 1 and 3 rooms. Blown coal was observed to the top (four feet deep) of the roof bolting machine in the No. 2 room just outby the last open crosscut. Blown coal was observed up to three feet deep in the other affected areas. A fine red or rust colored dust was present in all of the locations where coal was blown into the rooms and room crosscuts.
Roof deterioration accompanied the burst at several locations, further illustrating the violence of the event. Six inches to two feet of roof rock fell from around the roof bolts and straps in the No. 2 room. Timbers set at the mouth of the last open crosscut between the No's. 1 and 2 rooms were broken and the roof in that area was damaged. A heavy roof area developed in the No. 2 room starting at the second crosscut outby the gob and extended further outby through the opposite crosscut of the 2nd Left panel to the No. 3 entry of the 2nd Left panel. In addition, virtually all of the test holes in the No. 1 room and the last open crosscut of the rooms, contained cracks at depths ranging from 39 to 78 inches into the roof. These test holes were drilled during the advance mining cycle and reportedly were unfractured prior to the burst.
Roof conditions appeared stable over the remainder of the 005-0 section although occasional sounds, indicative of fracturing high in the roof strata, were heard by investigators on November 22, 1996. Pillar sloughing became progressively less severe away from the pillar line and burst area and was reduced to corner spalling in the 2nd Left panel, 1 to 2 crosscuts outby the gob end of the coal barrier. No floor heave was noted on the 005-0 section, but blown coal in the rooms and crosscuts prevented a thorough examination of bottom conditions in the burst area.
SUMMARY AND CONCLUSION
Cause of the Accident
The investigation team concluded that the increasing size of the frontal gob, the existence of a side gob, and increasing depth of overburden (in excess of 1,400 feet), resulted in high stresses and pressures on the coal pillars as they were extracted. The side gob had narrowed to approximately 130 feet wide adjacent to the accident site. The narrowness of the side gob may have restricted caving, contributing to excessive loading of the pillar line.
The presence of thick sandstone layers above and below the Creech coal seam enhanced the ability of the coal pillars to withstand high stresses and store energy. As room pillar No.1 was mined, much of its load was released and transferred to the already highly stressed adjacent pillars. This sudden pressure increase on the adjacent pillars was sufficient to cause failure of coal near or into the core of these pillars, and resulted in the burst.
The failure of the mine operator to fully address the above factors and direct adjustments sufficient to control the high ground pressures experienced by the active working section also contributed to the cause of the accident.
CONTRIBUTORY VIOLATION
30 CFR 75.202(a)
The coal ribs were not controlled to protect persons from the hazards of a coal burst in the three rooms in Second Left (MMU 005-0) off the Nine Right Panel, an active working section where persons worked and traveled. On November 20, 1996, retreat mining was started in the rooms and as the initial cut of coal was taken from the middle of the No. 1 pillar block, a coal burst was triggered. The coal burst damaged the coal ribs of all nine pillars in the rooms, blowing in excess of 1,500 tons coal into the room entries and crosscuts. The blown coal injured six miners, two fatally.
The potential for a coal burst was known to the mine operator, especially when mining beneath areas of high ground cover. The mine operator had made some adjustments to the numbers of and size of the pillars in the rooms in the Second Left section, however the adjustments were not sufficient to control the high ground pressures experienced by the active working section before the coal burst occurred.
Respectfully submitted
Billy G. Foutch
Supervisory Coal Mine Safety and Health Specialist
Charles H. Grace
Conference and Litigation Representative
Curtiss Vance
Coal Mine Inspector
Michael A. Evanto
Geologist
George J. Karabin, Jr.
Supervisory Civil Engineer
Danny Harmon
Supervisory Coal Mine Safety and Health Specialist (Roof Contorl)
Approved by:
Marvin W. Nichols, Jr.
Administrator
for Coal Mine Safety and Health
Related Fatal Alert Bulletin:
FAB96C34