DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
South Central District
Metal and Nonmetal Mine Safety and Health
Accident Investigation Report
Underground Metal Mine
Fatal Fall of Ground Accident
The Doe Run Company
Boss, Iron County, Missouri
I.D. No. 23-00457
January 19, 1998
Robert D. Seelke
Metal & Nonmetal Mine Inspector
Daniel J. Haupt
Supervisory Special Investigator
George J. Karabin
Supervisory Mining Engineer
William J. Gray
South Central District Office
1100 Commerce Street, Room 4C50
Dallas, Texas 75242-0499
Doyle D. Fink
Jeffrey Sadler, senior surveyor, age 33, was fatally injured at 9:45 a.m. on January 19, 1998, when he was crushed by a fall of ground from the back. Sadler had a total of eight years eleven months mining experience, all at this operation. He had received training in accordance with 30 CFR Part 48. Annual refresher training had been conducted on March 25, 1997.
MSHA was notified at 10:50 a.m., on the day of the accident by a telephone call from the safety director for the mining company. An investigation was started the same day.
The Casteel-Buick Mine/Mill, an underground lead/zinc operation, owned and operated by The Doe Run Company, was located near Boss, Iron County, Missouri. The principal operating official was Gary E. Boyer, vice-president of mining. The mine was normally operated two, ten-hour shifts a day, seven days a week. A total of 226 persons was employed.
The mine was developed by room and pillar mining. The Casteel and Buick mines were originally developed separately and later interconnected underground. After drilling and blasting, broken material was moved by front-end loader and truck to the production shaft where it was hoisted to the surface for processing.
The last regular inspection of this operation was completed on November 5, 1997. Another inspection was conducted following this investigation.
PHYSICAL FACTORS INVOLVEDThe accident occurred at the 81V20 stope, which was located in the northern portion of the Casteel Mine. Headings and crosscuts were mined a maximum of 32 feet wide and typical heights ranged from 16 feet to 18 feet. The dimensions of support pillars varied throughout the stope but, generally, a minimum size of 28-feet square, or equivalent area, was employed. Total overburden near the face was about 935 feet.
Specific locations in the mine were identified by their position in reference to the adjacent pillar. The open space by a pillar was referenced as "a" west, "b" northwest, and "c" north.
Full pattern rock bolting was not practiced at the Casteel Mine. Spot bolting (primarily brows and areas of concern identified by the miners) with 6-foot long fully grouted bolts, on roughly a 6-foot by 6-foot pattern, was observed at several locations in the stope. However, bolts had not been installed in or around the immediate ground fall area.
The nature of the ground in the 81V20 stope varied considerably. The ore deposit and back in the haulage heading was a tabular, laminated dolomite with layers up to 18 inches thick. This structure extended into and through crosscut 3112c to the left in the face area and at several other locations. The ground in and around the left and center headings was brecciated dolomite (angular rock fragments cemented together) that often appeared distorted or churned. Calcite or quartz crystals were sporadically observed along exposed facies.
A number of brows were observed throughout the 81V20 stope in both the brecciated and tabular dolomite back. The brecciated dolomite brows generally appeared stable and part of a more massive formation. The layered dolomite brows, depending upon thickness, appeared less stable and were bolted at several locations including the haulage heading adjacent to the fall. In this area an approximately 12-inch thick layer had been scaled from the intersection back (prior to mining the crosscut) after a shot had "burned" the back (penetrated to an undesirably high horizon) and left an irregular profile. While the brow appeared tight from the ground, close examination disclosed that it had separated from the overlying strata, 1/16-inch to 1/4-inch, around much of its perimeter.
No signs of excessive pressure were evident in the 81V20 stope. The pillars appeared solid with little or no spalling and no shear failure planes or tensile cracks were noted in the back or floor.
The brecciated dolomite back in the intersection 3127b and crosscut 3113c adjacent to the fall had domed out to a height of about 20 feet. Reportedly, that cavity began in the intersection of the left heading and incrementally unraveled and propagated toward the center heading, requiring additional scaling with each successive blast of the faces. The domed cavity in the crosscut 3113c between the left and center headings (indicative of locally weak ground) became shallower toward the intersection 3113b where the back elevation returned to the normal height of 16 feet to 18 feet (prior to the fall).
The ground fall occurred at the intersection at 3113b in the vicinity of survey station spad No. 4572. The widths of the heading and crosscut openings leading into the intersection ranged from 29 feet to 32 feet. The fall itself was approximately 10 feet wide by 20 feet long, 0 to 17 inches thick, and the total weight of the fallen material was estimated to be 12 tons.
The ground at the accident site appeared to be a junction or transition area between the brecciated dolomite on the left side of the 81V20 stope and the tabular formation on the right side. The fall occurred in the brecciated dolomite along the left side of the intersection 3113b, which appeared to be distorted and several calcite or quartz intrusions were evident. The right side of the fall appeared to abut a shallow brow roughly 12 inches thick near the southeast end of the fall that thinned to nothing near its northwest edge. The exact shape and composition of the fall could not be determined because of continued instability of the area during the accident investigation.
The generally accepted practice after blasting was to visually check for loose material and scale the back of a newly advanced heading. Blasting of the crosscut 3112c between the center and haulage headings adjacent to the fall occurred on the morning of January 17, 1998. Reportedly, the adjacent area had not been tested or scaled subsequent to blasting. Substantial scaling of the back adjacent to the ground fall was required during recovery efforts, and over a substantial portion of the left and center headings during the accident investigation.
The survey equipment used was a Total Station Model GTS212, infrared measuring device. Survey Stations were established by drilling 5/8-inch diameter by approximately 2-inch deep holes in the back, installing a 5/8-inch wood dowel into the hole and hammering a spad into the dowel and nailing a brass numbered tag to the dowel.
DESCRIPTION OF ACCIDENT
On the day of the accident, Jeffrey Sadler (victim) reported for work at 7:00 a.m., his regular starting time. Sadler and Jason Wruck, associate surveyor, attended a meeting at the main office where they gathered information and made sketches of the recent underground mine production. They went underground at about 8:10 a.m. and proceeded to the mine office where they picked up ear plugs.
Upon arrival at 81V20 stope, Sadler and Wruck parked their truck in 3101c crosscut and walked to 3109a heading where Alvin McWilliam, drill operator was moving his drill to the face in 3127a. They discussed the drill map with McWilliam and inquired where he would be drilling. Thad Pettit, underground associate, who was operating a mechanical scaler in the heading at 3125b, walked back to talk with them. McWilliam then moved his drill through intersection 3113b and crosscut 3113c to the face. McWilliam and Pettit said when they moved their drill and scaler through the 3113b intersection, they visually checked the back and did not see any loose material. Both the drill and scaler were equipped with multiple seal beam lights.
Sadler then set up his equipment at stations 4571 and 4549 to survey the areas. Afterward, he and Wruck went to station 4572 to survey the remaining portion of 3112c crosscut and 3124b face.
The surveyors had experienced problems hanging the plum wire on survey station 4572 spad in the past because it was bent, so they decided to change it out. Wruck drove the truck to crosscut 3113c and raised himself in the bucket. He removed the old spad and drove the new one into the wood dowel. At this time he did not see any loose ground and did not sound the back. He did notice that the station identification tag was damaged, so when he lowered the bucket he asked Sadler if he wanted it replaced. Sadler decided to use the station without the tag, so Wruck got down from the bucket and secured it to the truck bed, then backed the truck to the west rib in 3109a heading.
Sadler set up his equipment at station 4572 located in 3119b, while Wruck went to station 4570 with the leveling pole to shine his cap lamp for Sadler to back sight on. Sadler flashed his cap lamp indicating that he got it. Wruck was looking toward the ground as he walked back to the truck to get the prism pole and as he entered 3109a, he heard the ground fall. Wruck looked up and saw that the truck was smashed in front and there was a layer of fallen rock on the ground where Sadler had been standing.
Wruck ran around the north side of pillar 3109 where he met McWilliam who had been drilling and had heard the ground fall. The two men went to the fall, but could not see Sadler. They walked up the heading to pillar 3069, where McWilliam had parked his tractor and Wruck drove the tractor to the shop to get help. McWilliam went to the heading 3125a where Pettit was scaling and they both went back to the accident site.
Wruck met Phillip Hovis, mine general foreman, on the main roadway to the shop and informed him of the accident. Hovis then radioed for an ambulance. He instructed Wruck to go to the shop to get a stretcher and first aid supplies. Hovis took Wruck's tractor and went to the accident site.
By this time several other persons had arrived at the site. It was obvious that Sadler was dead. Hovis instructed the group to stay out of the area because the ground was not stable and then returned to the shop area to notify company officials and the coroner's office.
A recovery crew was established and the back in 3127b and 3113b intersections was scaled to stabilize the area. The crew used the mechanical scaler and scaling bars to move the rock in order to recover the victim.
The investigation revealed that the face in 3112c, which was about 17 feet from the fall of ground, had been blasted two days prior to the accident. Following the blast, the 3113b intersection had been visually checked by numerous miners but had not been tested for loose ground.
The cause of the accident was the mine operator's failure to test and scale the back in the intersection after blasting in the adjacent crosscut and failure to support or take down ground in the immediate area that created hazardous conditions.
Order Number 4445188, was issued on January 19, 1998 under the provision of Section 103(k):
Citation Number 7859810, was issued on February 24, 1998 under the provision of Section 104(d)(1), for violation of 30 CFR Part 57.3401:
An approximately 10 feet by 20 feet by 0 to 17 inch thick fall of ground occurred in stope 81V20 at the intersection known as 3113b on January 19, 1998 at 9:45 a.m. fatally injuring a miner who was setting up his survey equipment under the number 4572 survey station. This order prohibits any work within the boundaries of pillars 3112, 3081, 3101 & 3113 until MSHA has determined that the ground conditions no longer present a hazard to miners.
A fatal accident occurred at this operation on 1/19/98, when a large slab fell on a miner who was setting up a surveying instrument at intersection 3113b in stope 81V20. The slab was approximately 10 feet wide, 20 feet long and was up to 17 inches thick. The ground at this location had been visually examined, but testing for loose ground had not been done. Significant amounts of loose ground had been scaled in the intersections east and west of the fall during the weeks prior to the accident, which was indicative of loose ground conditions in this area of the mine. The mine operator was aware of the loose ground conditions in this part of the mine and failed to adequately test in the intersection where the accident occurred. This is an unwarrantable failure to comply with a mandatory safety standard.Order Number 7859811, was issued on February 24, 1998 under the provision of Section 104(d)(1), for violation of 30 CFR Part 57.3200:
A fatal accident occurred at this operation on 1/19/98, when a large slab fell on a miner who was setting up a surveying instrument at intersection 3113b in stope 81V20. The slab was approximately 10 feet wide, 20 feet long and was up to 17 inches thick. The ground at this location had been visually examined, but testing for loose ground had not been done. Significant amounts of loose ground had been scaled in the intersections east and west of the fall during the weeks prior to the accident, which was indicative of loose ground conditions in this area of the mine. There was no evidence to indicate that efforts had been made to take down the loose rock or to support the ground in the fall area. This is an unwarrantable failure to comply with a mandatory safety standard.Order Number 7859812, was issued on February 24, 1998 under the provision of Section 104(d)(1), for violation of 30 CFR Part 57.3202:
A fatal accident occurred at this operation on 1/19/98, when a large slab fell on a miner who was setting up a surveying instrument at intersection 3113b in stope 81V20. The slab was approximately 10 feet wide, 20 feet long and was up to 17 inches thick. The ground at this location had been visually examined, but testing for loose ground had not been done. Significant amounts of loose ground had been scaled in the intersections east and west of the fall during the weeks prior to the accident, which was indicative of loose ground conditions in this area of the mine. The mine operator was aware of the loose ground conditions in this part of the mine and failed to provide a scaling bar for the surveying crew at this location for scaling the back and ribs. This is an unwarrantable failure to comply with a mandatory safety standard.
Related Fatal Alert Bulletin: