DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
District 7
ACCIDENT INVESTIGATION REPORT
(Underground Coal Mine)
FATAL FALL OF RIB
No. 37 Mine (I.D. 15-04670)
Arch of Kentucky
Cumberland, Harlan County, Kentucky
December 26, 1997
by
Dennis J. Cotton
Mining Engineer
Originating Office - Mine Safety and Health Administration
Coal Mine Safety and Health, District 7
H.C. 66, Box 1762, Barbourville, Kentucky 40906
Joseph W. Pavlovich, District Manager
Report Release Date: May 9, 1998
OVERVIEW
Abstract
At approximately 10:20 A.M. on Friday, December 26, 1997, a fatal fall of rib accident occurred at the Arch of Kentucky, No. 37 Mine.
Barney Wayne Clay, age 47, continuous miner operator with 25 years of mining experience, suffered fatal crushing injuries while tramming the continuous miner to the face of the No. 3 entry on the 016 MMU. The victim was operating the machine by remote control proceeding up the No. 3 entry when the rib fell striking him and resulting in fatal injuries. The fall of rib measured 23 feet long, 10 feet 07 inches high, and up to 42 inches thick.
The coal rib collapsed as a result of the release of strain energy in pillars designed to yield for the purpose of reducing the potential for coal "bumps" in the area. The failure of the mine operator to support or to otherwise control the rib where persons are required to work and travel
contributed to the accident.
The No. 37 Mine, located in Cumberland, Harlan County, Kentucky, is operated by Arch of Kentucky, a division of Apogee Coal Company. The mine employs 126 persons underground and six persons on the surface. The mine is opened by nine drifts into the Harlan seam which averages 120 inches in thickness. The mine produces coal on two shifts per day five days per week with maintenance and support work being performed on third shift.
Two (2) continuous-mining machine sections produce and average of 3,964 clean tons daily. Coal is transported from the face areas to the to the dumping point by a continuous haulage system. Coal is then discharged onto a series of belt conveyors and transported to the stockpile area located on the surface. The raw coal is processed through a preparation plant and the clean coal is then stored in a silo to be loaded onto railroad cars for shipment to various customers. The land was owned in fee by Ark Land Company which is a landholding company for Arch Minerals.
The principal officers of the operation are as follows:
Lonnie Lowe..................................Mine Manager
J.M. Vicini......................................Manager - Safety and Health
The last MSHA regular Safety and Health Inspection (AAA) was completed on December 19, 1997.
DESCRIPTION OF THE ACCIDENT
Paul Royce, foreman for the Number 3 Bridge Section, and his crew started the day shift at 8:00 a.m. on December 26, 1997 by traveling to the Number 3 Bridge Section. Upon arrival at the section power center, Paul Royce had a short safety talk with the crew before work began. Royce then conducted an examination across the section. No hazards were noted or recorded. Normal work operations then began as scheduled.
The continuous miner began mining coal in the No. 1 right crosscut. Roof bolting operations were being conducted in the No. 3 heading. After the No. 3 heading was completely bolted, the working place was scooped and ventilation tubing was advanced to the face along the left rib. The scoop traveled to the No. 1 entry, loaded the protective cage (a structure the continuous miner operator and the miner helper occupy during mining and designed to minimize the potential of injury from a fall of rib or roof) and transported it to the No. 3 working place where it was installed. Royce, section foreman, next conducted the on-shift examination for the No. 3 working place before issuing instructions for the continuous miner to tram to the new working place to resume mining. Completing his examination and reportedly finding no hazards, Royce traveled to the No. 1 entry and instructed Barney Clay, continuous miner operator and victim, and George Birman, continuous miner helper, to tram the miner to the No. 3 heading and begin mining.
Clay trammed the continuous miner, using remote control through the last open crosscut to the No. 3 working place. At approximately 10:20 a.m., as Clay followed the continuous miner, a coal rib collapsed knocking him to the mine floor. The section of rib measured 23 feet long, 10 feet 07 inches in height, and up to 42 inches thick.
Clay was found by two co-workers, George Birman, his helper, and Ottis Gilliam, shuttle car operator, who had been observing the continuous miner's cable. Clay was discovered lying approximately seven (7) feet out in the entry face down with loose coal and rock covering him from just above his knees to his feet. The victim was reportedly conscious and alert when he was discovered.
The rock was removed from the victim by Birman and Gillian. The victim was then placed on a stretcher for transportation out of the mine. Upon arrival on the surface the victim was examined by an Emergency Medical Technician and transported by a Johnson Life Care ambulance to the Harlan Appalachian Regional Hospital. Clay's condition worsened and he was subsequently air lifted to the U.K. Regional Hospital where he died at 4:40 p.m. as a result of respiratory arrest due to post trauma pulmonary insufficiency.
INVESTIGATION OF THE ACCIDENT
At approximately 2:00 p.m. on December 26, 1997, Daniel L. Johnson, Supervisory Coal Mine Safety and Health Inspector of MSHA's Harlan, Kentucky Field Office, was notified by J.M. Vicini, Manager of Safety and Health of Arch of Kentucky, that a serious accident had occurred. The MSHA accident investigation team was assembled and arrived at the mine at 3:45 p.m. A 103 (k) Order was issued to ensure the safety of the miners until an investigation could be conducted.
MSHA and the Kentucky Department of Mines and Minerals jointly conducted the investigation with the assistance of mine management, miners, and representatives of the miners.
PHYSICAL FACTORS INVOLVED
The following physical factors were determined to be relevant to the occurrence of the accident.
- The accident occurred underground on the 016 MMU at the Arch of Kentucky, No. 37 Mine, I.D. No. 15-04670.
- The victim was tramming a 12CM12 Joy Continuous Mining machine (serial No. JM4655R) when the fall of rib accident occurred.
- According to the Approved Roof Control Plan entries were to be, " mined at a maximum 18 feet width to aid rib control measures and to maintain the maximum entry width to 20 feet or less." The entry width subsequent to the accident was measured at 20 feet - 02 inches.
- According to the report dated March 7, 1997 and prepared by John T. Boyd Company, Mining and Geological Consultants, the resultant pillars left from mining the barrier pillar had been designed to yield slightly to reduce the potential of coal bumps in the area by minimizing the stored strain energy in the pillars.
- The overburden in the area of the accident is approximately 1600 feet in thickness and is composed of sandstones, siltstones, shales and coals.
- The background noise created by the auxiliary fan located from the accident scene to approximately 50 feet outby in the No. 3 entry limited the persons in the area from hearing surrounding sounds such as might be generated from stresses in the mine roof or ribs.
- A pre-shift examination of the 016 MMU (No. 3 Bridge Section) was conducted by Mike Sergent, foreman, for the day shift between 6:30 and 7:00 on December 26, 1997. The on-shift examination of the No. 3 entry was conducted by Paul Royce, foreman, at 10:10 a.m., approximately ten (10) minutes before the accident. There were no hazards recorded as being in
the area of the accident in either examination.
- Statements obtained from interviews of co-workers and the foreman indicated that there were no visible signs of roof or rib abnormalities or deterioration observed in the area that fell prior to the accident.
- The material that collapsed from the right rib consisted of; rock binder, coal, and rock intermixed. The material measured 23 feet in length, 10 feet 07 inches in height, and up to 42 inches in thickness.
DISCUSSION
The No. 37 Mine was originally developed to extract the Harlan seam coal reserve boundary by the longwall method of mining. Longwall mining continued in the mine until September 1997, at which time all feasible reserves that could be mined by the longwall method were depleted. The operator continued to mine the remaining reserves by the room and pillar method of mining. These reserves were located along the outer perimeter of the areas longwalled, and also in barrier blocks which had been left to protect the main entries in the mine. The present works consists of two active working sections, mains, panels, and an extensive gob consisting of mined-out workings and bleeder entries.
The accident and injury history for the No. 37 mine from 1993 to the present was reviewed by the investigator. Seventeen (17) injury accidents involved falls of roof and rib, six of which were from falls of rib. The incident rate of roof and rib fall accidents of this mine is almost twice the national average. The rate for this mine was computed to be 2.10 compared to 1.10 for the nation.
Due to the height and nature of the coal seam, and the pressures exerted on the ribs by the overburden, rib control has been a constant concern at this mine. The Roof Control Plan, approved November 3, 1997 includes several safety precautions to protect miners from fall of rib accidents. The following precautions are included in the Rib Control portion of the Roof Control Plan:
- "No employee shall be allowed inby the last open crosscut in an entry where coal is being mined except those persons deemed necessary.
- Overhanging ribs that develop on the working section shall be taken down or supported.
- A bar of suitable for prying down loose materials will be available in outby areas.
- Management will educate and train all personnel about the dangers of falling ribs and instruct them on the necessary safety precautions.
- On active units, a mobile equipment operator (shuttle car, scoop, etc.) will be designated to examine the coal ribs for potential hazardous conditions during each production shift. This examination will be done continuously while the employee is performing his assigned duties. At
no time will any employee be required to pull a coal rib without another employee present. Any hazardous coal rib conditions will be immediately reported to the section supervisor who has the responsibility to see that the condition is corrected in a timely manner.
- Entries will be mined at a maximum 18 feet width to aid rib control measures and to maintain the maximum entry width to 20 feet or less."
- According to the Approved Roof Control Plan, to enhance safety while mining extended cuts, a cage for the continuous miner operator and the miner helper to stand in will be provided during cuts. The cage protects the continuous miner operator and the miner helper from rib rolls and the shuttle cars operating in the area.
At the time of the accident the 016-0 MMU, #3 bridge section, had begun to advance mine the 350 feet wide barrier pillar by developing three entries on 90 feet x 120 feet wide centers. The section advanced approximately 200 feet into the barrier before the fatal accident occurred. Inspection of all areas of the working section approximately six hours after the accident revealed loose, broken and overhanging ribs in the No. 1, 2, and 3 entries. The loose and broken ribs found in the No. 1 and 2 entries ranged between 4 to 18 inches in thickness and from 10 to 11 feet in height. These conditions, constituting violations, in other areas of the working section were cited separately, not in conjunction with this accident.
The resultant pillars left from mining the barrier pillar were designed to yield slightly to reduce the potential of coal bumps in the area by minimizing the stored strain energy in the pillars. Although this design would reduce the potential for outbursts, allowing pillars to yield in the high load environment creates a higher risk of rib rolls than pillars designed sufficiently large to support most or all the overburden load above the pillar.
CONCLUSION
The coal rib collapsed as a result of the release of strain energy in pillars designed to yield for the purpose of reducing the potential for coal "bumps" in the area. The failure of the mine operator to support or to otherwise control the rib where persons are required to work and travel contributed to the accident.
ENFORCEMENT ACTIONS
- A 103 (k) Order, No. 4864021, was issued to ensure the safety of the miners until an investigation could be conducted.
- 104 (a) Citation, No. 7452045, was issued for a violation of Title 30, Part 75.202 (a), for the mine operator's failure to support or otherwise control the rib where persons were required to work and travel.
Submitted by:
Dennis J. Cotton
Mining Engineer
Approved by:
John M. Pyles
Assistant District Manager
for Enforcement
Joseph W. Pavlovich
District Manager
Related Fatal Alert Bulletin:
FAB97C30