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Accident Investigation Report
Underground Metal Mine

Fatal Slip/Fall of Person Accident

San Manuel Mine
Mine I.D. No. 02-00151
BHP Copper
San Manuel, Pinal County, Arizona

April 22, 1997


Tyrone Goodspeed
Supervisory Mine Safety & Health Inspector

John R. King
Mine Safety & Health Inspector

Rocky Mountain District
P.O. Box 26367, DFC
Denver, CO 80225-0367

Robert M. Friend
District Manager


Alberto Aguirre, car loader, age 21, was fatally injured on April 22, 1997, when he was run over by an ore car. He had a total of 14 weeks mining experience, 5 weeks with BHP Copper and 9 weeks with Frontier Kemper, all at this operation. BHP Copper training records indicated that he had received 40 hours newly employed, inexperienced miner training; hazard training, which included the use of shelter holes (pony sets); and task training for car loaders.

A MSHA regular inspection was ongoing at the time of the accident. Company officials notified the inspectors of the accident and an investigation was started the same day.

Principal operating officials for BHP Copper were:
Terrell I. Ackerman, General Manager Steven D. Lautenschlaeger, Manager-Sulfide Mining Ward L. Lucas, SMO Safety & Health Manager Warren C. Traweek, Manager, Safety & Health

The San Manuel Mine, owned and operated by BHP Copper, was located near San Manuel, Pinal County, Arizona. Sulfide ore was mined by the block-caving mining method. A horizontal slice of ore was removed weakening the stability of the ore body above the slice and causing the ore to fall into an underlying haulage level. Rail cars then transported the ore to vertical shafts where the ore was hoisted to the surface. On the surface ore was stored in bins until it was loaded into ore cars for transport to the mill.

Total employment at the mine was approximately 1,600 persons working three, 8 hour shifts per day, 7 days a week.


The accident occurred on the 2675 level of the mine in haulage panel 16B at pony set 37E where ore car loading was being performed.

At the time of the accident, two 20-ton Goodman electric haulage motors, working in tandem, were pulling 18 loaded ASEA bottom-dump ore cars through the panel. Each ore car was rated at 18 ton capacity and measured 18 feet, 11 inches long; 6 feet, 1 inch high; and 6 feet, 7 inches wide. A 5th wheel used in dumping the cars was attached to the right side of each ore car. The wheel protruded 4 inches from the side of the car and was 16 inches in diameter. The bottom of the wheel was about 4 inches from the muddy floor. There was corrosion on a flange and on the 5th wheel of car 736, which was the 6th car in the 18 car train moving the ore. Observations made during the investigation showed that the corrosion on the flange and wheel had been disturbed. (See Appendix #3, Photo #1)

The 16-B panel haulageway was primarily used by ore trains and mine service equipment. The panel measured approximately 1,900 feet long and extended from the south to the north turnouts. The vertical distance from the track rail to the panel drift back (roof) was 9 feet, 4 inches and the rib-to-rib distance measured 12 feet, 5 inches.

The 36-inch gage, 119 pound/foot rails were straight, level, and were maintained in good condition. Trains normally traveled through the panel in a south to north direction.

The pony set, an elevated frame or structure in the haulageway, was also designated as a "shelter hole area". The pony set was positioned 9 feet, 8 inches above the floor and track.

Chute control operations for loading ore cars were accomplished from the pony set. Access to the pony set was provided by a company fabricated steel ladder made of rebar material. The ladder was 11 inches wide with rungs on 12-inch centers. The ladder was installed at an 8 degree angle to the right when facing it. The lower and upper sections of the ladder were offset (did not join evenly). The ladderway opening in the floor of the pony set measured 22 inches by 32 inches. Loose, wet unconsolidated material had accumulated at the base of the ladder. (See Appendix #3, Photo #2)

In May 1995, a variance was approved for Levels 2675 and 2950 under the petition for modification rules of the Mine Safety and Health Administration. The modification permitted the former mine operator to designate and use pony sets as shelter holes meeting the safety requirements appearing in 30 CFR 57.9360(a)(2). The approved modification had two conditions related to this accident: (1) each haulage panel was required to have at least two posted signs informing miners to use the pony sets when trains were in the panel; and, (2) requiring that shelter hole access areas be kept clean and orderly as required by 30 CFR 57.20003(a).


Alberto Aguirre, victim, reported for work at 8:00 a.m., his normal starting time. After receiving work assignments from Mike Arvayo, No. 2 crew production team leader, the crew traveled to 16B haulage panel. Aguirre was assigned to load ore cars from 16B panel, pony set 37E.

The train Aguirre assisted loading was the first of the shift. After the ore cars were loaded, the train motorman received a signal from Russell Kent, car loader, to leave the panel. Kent was in pony set 32 at the end of the train.

At approximately 9:30 a.m., as the train started moving out of the panel, a signal to "stop" was initiated. The motorman immediately stopped the train. Kent, who gave the signal to "move out", suspected that something had happened because it was normally his duty as last car loader to signal the motorman, unless there is an emergency elsewhere in the panel.

Kent began walking north from the pony set where he was located and traveled about 200 feet when he observed Aguirre lying on the floor at pony set 37E, next to an ore car. He was not moving. Another car loader, Dan MacKay, in pony set 41, was notified that Aguirre was injured. MacKay stated that he did not signal for the conveyance to stop.

The car loaders saw Aguirre's cap lamp cord wrapped around the pony set access ladder approximately 8 inches above the mine floor. Additionally, the pony set signal cord was not hanging down in the usual location but was hanging from metal piping next to the access ladder, 7 feet, 6 inches from the floor. Aguirre's hardhat was under the right side of his chest. The position of Aguirre's body, and the locations of the lamp cord and the pony set signal cord, indicated that Aguirre had been struck by the 5th wheel of an ore car after he pulled the signal cord to stop the train.

The two car loaders administered first aid, notified the No. 2 crew dispatcher of the accident, and moved him to the 16A crosscut. The victim was loaded on a stretcher and transported to the No. 5 shaft station and to the surface medical facilities.

At 10:30 a.m., the doctor at the San Manuel Health Care Center pronounced Aguirre dead due to crushing injuries.


The cause of the accident include the following:
1. After loading the train ore cars, the victim did not remain in the shelter hole until the train had passed.

2. A safe means of access to the pony set/shelter hole was not provided, in that, the ladder was tilted 8 degrees to the right and was offset from the upper ladder section, which made the rungs slant toward the haulage panel track.

3. The immediate area of 16B-37E pony set/shelter hole was not maintained in a clean and orderly condition.


Order No. 4701709
Issued at 10:15 a.m., April 22, 1997, under the provisions of Section 103 (k) of the Mine Act:

The company has experienced a fatal accident on 2675, Panel 16 Baker, line 37. This order is issued to protect the miners in the area from a recurrence and pending an investigation by MSHA.

This order was terminated on completion of the onsite investigation on April 23, 1997.

Citation No. 7915017
Issued under the provisions of Section 104(a) on May 30, 1997, for violation of 57.9360(a)(1):

A fatal accident occurred at this operation on 4/22/97, when a miner fell from a pony set (shelter hole) ladderway at panel 16B-37E, on the 2675 foot level. He was descending the ladderway when he fell and was run over by the fifth wheel of a loaded ore car being pulled from the panel. Under mandatory conditions set forth in a granted Petition for Modification, Docket M-94-04-M, miners are required to remain in pony sets when trains are moving through a panel.

Citation No. 7915018
Issued under the provisions of Section 104(a) on May 30, 1997, for violation of 30 CFR 57.20003(a):

A fatal accident occurred at this operation on 4/22/97, when a miner fell from a pony set (shelter hole) ladderway at panel 16B-37E, on the 2675 foot level. Loose, wet material (muck) had been allowed to accumulate on the passageway at the base of the ladder to the shelter hole.

Citation No. 7915019
Issued under the provisions of Section 104(a) on May 30, 1997, for violation of 30 CFR 57.11001:

A fatal accident occurred at this operation on 4/22/97, when a miner fell from a pony set (shelter hole) ladderway at panel 16B-37E, on the 2675 foot level. The ladder was installed at an approximately 8 degree angle to the right, which created a 15-inch offset between the bottom and the top of the fixed anchor locations.

//s// Tyrone Goodspeed
Supervisory. Mine Safety & Health Inspector

//s// John R. King
Mine Safety & Health Inspector

Approved by: Robert M. Friend, District Manager

Related Fatal Alert Bulletin:
Fatal Alert Bulletin Icon [FAB97M24]