DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
Rocky Mountain District
Metal & Nonmetal Mine Safety and Health
Accident Investigation Report
Underground Metal Mine
Fatal Fall of Ground Accident
San Manuel Mine
San Manuel, Pinal County, Arizona
Mine I.D. No. 02-00151
March 4, 1998
Richard R. Laufenberg
Supervisory Mine Safety and Health Inspector
Arthur L. Ellis
Mine Safety and Health Inspector
George J. Karabin, Jr.
Supervisory Civil Engineer
James M. Kramer
Rocky Mountain District
P.O. Box 25367, DFC
Denver, CO 80225-0367
Robert M. Friend
Arlo Wade, drift and crosscut miner, age 47, was fatally injured at about 8:30 p.m., on March 4, 1998, when he was struck by a rock that fell from the back. Ronald Larry Byrd, was also seriously injured in the same accident. Byrd had a total of 15 years 1 month mining experience, 9 years 1 month at this mine, and 9 months installing ponysets in raise stations. Wade had a total of 19 years 1 month mining experience, 2 1/2 years installing ponysets. Both had received training in accordance with 30 CFR, Part 48.
MSHA was notified at 9:50 p.m., on the day of the accident by a telephone call from Ward L. Lucas, safety manager for the mining company. An investigation was started the same day.
The San Manuel Mine, an underground copper operation, owned and operated by BHP Copper, was located near San Manuel, Pinal County, Arizona. The principal operating official was Douglas McGregory, general manager. The mine was normally operated three, 8-hour shifts a day, seven days a week. A total of 1,319 persons was employed.
Sulfide ore was mined by full-gravity block-caving mining method that consisted of a draw point(grizzly) level, an undercut level and a haulage level. Levels were identified according to depth below the surface. Ore was transported by rail cars and belt conveyors to vertical shafts and hoisted to the surface.
The last regular inspection at this operation was completed on January 15, 1998. Another inspection was conducted at the conclusion of this investigation.
PHYSICAL FACTORS INVOLVEDThe fall of ground occurred during the installation of metal frame ponyset supports in the 21 raise station, panel 12 south, on the 3570 haulage level that serviced the 3440 grizzly level located 130 feet above. An undercut level was positioned 23 feet above the draw (grizzly) level. Service/conveyor drifts (3600 level) were located 30 feet below the haulage level.
The ground at the accident site was composed of granodiorite porphyry with potassic alterations. The surface of the fall cavity appeared to have a "veined" texture that contained a number of small fractures. After initial development, the ground in the vicinity of raise station 21 had been supported with a combination of 8-foot split set friction rock stabilizers on a 30-inch by 30-inch pattern and wire mesh. Ground timber consisted of three sets of lower legs and collars which left an area of back roughly 12 feet by 13 feet.
The ground fall occurred in the southwest portion of the raise station during installation of the first cap beam. The installation of the four posts and collar braces of the ponyset had already been completed. The back had recently been blasted an additional 8 1/2 to 9 feet in height to accommodate the structure. Holes were drilled in the entire area on 2 1/2-foot centers width-wise and on 3-foot centers length-wise, with two relief holes. However, twelve holes on the northeast side had not been charged and would be shot later. This created a small brow across the northeast portion of the raise station that tapered from the original back elevation at the northeast edge to the blast horizon near the center of the raise station. Reportedly, secondary blasting was done along both the east and west sides of the raise station. Rock bolts or temporary supports were not used to support the ground after blasting.
The fall area was approximately 8 feet by 10 feet and varied from 6-inches to 3 1/2 feet thick. Exact measurements were not made due to continued instability of the area during the investigation. The fall was trapezoidal in shape and extended over the southwest rib for a distance of up to 18 inches. The rib appeared fractured and crumbly and was held in place by split sets and wire mesh. A smooth-planar surface slip formed the southwest side of the fall and the exposed surface was estimated to be roughly 6 feet long and 3 1/2 feet high at its apex. The fall peaked over the west leg of the base frame and tapered to nothing around its perimeter. The rock that struck the victim was about 2 feet by 3 feet and varied from 12 inches to 3 feet thick.
The east rib was also supported by a combination of split sets and mesh, and while it was fractured, deterioration was not as severe as noted on the west rib. No significant deterioration was noted in the north end of the raise station adjacent to the fall.
Ground conditions in permanently supported areas adjacent to the accident site appeared stable. No damage was observed in the concrete liner of the panel 12 haulage drift throughout its length and no unusual conditions were evident in the raise stations that had not been completed.
Accounts provided by witnesses to the accident indicated that after blasting and scaling of raise station 21, the ground began working. On several occasions construction efforts were halted.
DESCRIPTION OF ACCIDENT
On the day of the accident, Arlo Wade (victim) and Ronald Larry Byrd (injured) reported for work at 3:00 p.m., their usual starting time. Wade and his partner, David Terry, were instructed by Hector Dinogean, leadman, to install ponyset support steel in the 21 raise station, panel 12 south, on the 3570 level. Wade and Terry were informed that the initial round to develop the raise station had been blasted at the end of the prior shift. Denogean instructed Byrd and his partner, John Velasques, to install rock bolts in a stub drift located just off panel 12 south on the 3570 level, between raise stations 17 and 18.
Wade and Terry arrived at the 21 raise station at about 3:45 p.m., and began constructing the ponyset. Wade asked Byrd and Velasques to shut down the LHD they were operating because the ground was working in the raise station. They shut the engine off and returned to the stub drift and began installing rock bolts. Wade and Terry also asked Ronald Paulsen and Felix McCallaum, contract miners employed by Frontier Kemper Constructors, to shut down the LHD they had been operating in panel 12 south near the 21 raise station for the same reason. Wade and Terry were forced to leave the raise station several times during the shift due to ground activity.
At about 7:15 p.m., Denogean arrived in panel 12 south and met with Byrd and Valasques and then proceeded to the 21 raise station. He met Paulsen and McCallaum on the north side of the raise station. They informed him that Wade and Terry had told them not to operate their equipment because the ground was working in the raise station. Denogean instructed them to stand by and keep an eye on Wade and Terry.
A few minutes later, Wade and Terry approached Denogean. They discussed the ground conditions and the amount of cribbing material needed to complete the job. While Denogean was present, a fall of ground occurred from the back directly above the area where the ponyset was being installed. The rock was about 3 feet by 2 feet and 18 inches thick. Denogean instructed Wade and Terry not to be in the raise station when the ground was working and that Byrd and Velasques were working in the stub drift if they needed help. Denogean left the area at about 7:30 p.m.
Wade and Terry waited until they felt it was safe to continue installing the ponyset. At 8:00 p.m., Byrd and Velasques had moved from the stub drift to the north side of the muck pile to eat lunch and to check on Wade and Terry. At about 8:30 p.m., Byrd offered to help install the ponyset. They were lifting the first metal cap beam onto the post when rock fell from the back, striking the three miners.
Paulsen saw the fall of ground and, along with McCallaum and Velasques, began searching for the three miners. Byrd crawled and Terry walked out of the area where the fall occurred. Paulsen found Wade covered with rock on the wood floor of the raise station.
Terry was treated at the mine for a small cut on his left shoulder. Byrd and Wade were transported to a health care center in San Manuel, Arizona, where Wade was pronounced dead. Byrd was examined and air-lifted to a hospital in Tucson, Arizona, where he was treated for a cervical fracture. He was released from the hospital on March 7, 1998, and was expected to fully recover.
The accident was caused by the failure to take down or support loose ground.
VIOLATIONSOrder No. 4886481 was issued on March 4, 1998, under the provisions of Section 103(k) of the Mine Act to ensure the safety of persons in the area until the mine can be returned to normal operation as determined by an authorized representative of the Secretary.
This order was terminated on March 7,1998, after it was determined that the mine could be safely returned to normal operation.
Citation No. 7922329 was issued on March 13, 1998, under the provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 57.3200:
A fatal accident and a serious injury occurred on March 4, 1998, at the 21 raise station, panel number 12 south, when a fall of ground occurred while three miners were installing a raise station ponyset. The loose ground had not been taken down or supported. A visit had been made to the work area by the supervisor approximately one hour prior to the accident and he was aware that hazardous ground conditions existed. The supervisor engaged in aggravated conduct constituting more than ordinary negligence, in that prior to the ground fall he was aware that the miners were working under dangerous unsupported ground that was moving and dribbling. This is an unwarrantable failure to comply with a mandatory standard.
Citation No. 7922328 was issued on March 13, 1998, under the provisions of Section 104(a) of the Mine Act for violation of Section 103(a) of the Mine Act:
The operator impeded MSHA's investigation into a March 4, 1998, fatal accident by withholding vital information requested by the MSHA accident investigation team. At a meeting at 9:00 a.m., on March 6, 1998, between MSHA and the operator representatives, the MSHA accident investigation team requested the address and telephone number of Ronald Byrd, an employee of BHP Copper and a miner at the San Manuel Mine, who had been injured in the accident. Ronald Byrd was an essential witness in the accident investigation, and the MSHA accident investigation team needed to contact him for an interview. The mine operator refused to provide MSHA with this information. Operator representatives present at that meeting included Ward Lucas, safety manager, BHP Copper; Warren Traweek, manager, safety and health, security-North American Division, BHP Copper; and Mark Savit of Patton Boggs, legal counsel for BHP Copper.
This citation was terminated on March 13, 1998. The mine operator provided MSHA written documentation regarding the address and telephone number where Ronald Byrd resided.
Related Fatal Alert Bulletin: