MINE SAFETY AND HEALTH ADMINISTRATION
Metal and Nonmetal Mine Safety and Health
Accident Investigation Report
Underground Metal Mine
Fatal Handtools Accident
Getchell Gold Corporation
Turquoise Ridge Mine
Golconda, Humbolt County, Nevada
ID No. 26-02286
February 15, 1999
Supervisory Mine Safety and Health Inspector
Mine Safety and Health Inspector
J. Jarrod Durig
Western District Office
Mine Safety and Health Administration
2060 Peabody Road, Suite 610
Vacaville, CA 95687
James M. Salois
Thomas Gross Jr., miner, age 28, was killed and Thomas Crowley, miner, was seriously injured at 4:20 p.m. on February 15, 1999, when they were struck by an air hose. Gross had 3 years and 4 months total mining experience, three weeks as a miner at this operation. Crowley had 7 years total mining experience and also had worked for three weeks as a miner at this operation. They had received training in accordance with 30 CFR Part 48.
MSHA was notified at 6:00 p.m. on the day of the accident by a telephone call from the safety supervisor for the mining company. An investigation was started the same day.
The Turquoise Ridge Mine, a multi-level underground gold operation, owned and operated by Getchell Gold Corporation, was located 28 miles northeast of Golconda, Humbolt County, Nevada. Principal operating officials were Wade Bristol, general manager; Michael Owsley, mine operations manager; and Patrick Allen, loss control manager. The mine was normally operated two, 12-hour shifts a day, seven days a week. A total of 200 persons was employed; of this number, 140 worked underground.
Gold bearing ore was drilled and blasted in open stopes. Broken material was transported from the stopes on haulage trucks to ore chutes, then crushed and hoisted to the surface. Depending on grade, the ore was either milled or hauled to a cyanide leach pad for processing. The milled or leached product was sent to the plant refinery for removal of impurities and pouring into dore` bars. These bars were transported to refineries off site for final processing prior to sale to customers.
The last regular inspection of this operation was completed on December 14, 1998.
PHYSICAL FACTORS INVOLVED
The accident occurred at the intersection of the TR1550 ramp and TR3955 access drift where an air supply line was being installed at the intersection.
Compressed air to the supply line was provided from both the No. 1 and No. 2 Shafts. Air came from the 1250 and 1550 levels and was connected on the 1550 level to create a continuous loop. Two valves, one on either side of TR3955 access drift were installed to depressurize the air supply line. Operating pressure was approximately 120 psi. The air line was composed of 20 foot sections of 6-inch diameter, 20-gauge rolled groove steel pipe, Victaulic couplings, 6-inch to 4-inch diameter Victaulic reducers, Victaulic 4-inch Series 700 butterfly valves, and 4-inch diameter King combination nipples.
A 4-inch diameter Dayco Thoro-Braid wire braided rubber hose approximately 30 feet long was connected to a butterfly valve. The hose was used to connect sections of air line across drift intersections and was rated at 400 psi maximum working pressure. The butterfly valve and hose were connected by a 4-inch combination nipple manufactured by Dixon Valve and Coupling Company. The nipple was made of Schedule 40 steel pipe and measured 7 1/4 inches long with a 3 3/4-inch long male threaded end that fit into the hose. The manufacturer's specifications stated that "Combination nipples are recommended for low pressure discharge and suction service. The working pressure of combination nipples varies with the size of the nipples and size and construction of the hose and type clamping device used. Not intended for compressed air." However, use of these nipples was not considered a factor that contributed to this accident.
The air line was reduced from 6 inches to 4 inches at the joints where a rubber hose was used. A Victaulic style 77, 4-inch flexible coupling connected sections of the air line and rubber hose together. The metal coupling was a two-piece, ductile iron housing fastened together with two, 3 1/4-inch long by 5/8-inch diameter bolts and nuts. The coupling was designed to fit the grooves in the pipe. A solid rubber seal was centered over the ends of the two pipes inside the coupling. The coupling and seal assembly was rated for 1,000 psi maximum working pressure.
A butterfly valve was used to control the air supply to various sections of the system. The valve body was cast of ductile iron and the valve disc was made of aluminum bronze. The valve could be locked in either the full open or full closed position by turning a lever type handle 90 degrees. The valve assembly was rated for bubble-tight shut-off to 200 psi.
A Normet Scissors Lift vehicle was used for access to the air line and was parked parallel to the rib at the intersection of the TR1550 ramp approximately two feet from the rib. At the time of the accident, the scissors lift work deck was raised to a level that the two miner's shoulders were even with the air line.
A written company policy, dated June 19, 1995, and revised June 9, 1997, regarding working on compressed air stated, in part "Do not connect, disconnect, or repair any water or air hose, pipe, machine, or equipment that is under pressure: bleed the line and receivers first and keep them bled until the job is finished." This policy also required that all air shut-off valves be tagged and locked out prior to work being performed on air lines. Further, the policy required that safety clips or whip check devices be used at compressed air connections to machines or high pressure hose lines of 1-inch diameter or larger and at all hose connections.
DESCRIPTION OF ACCIDENT
On the day of the accident, Thomas Gross, Jr., (victim) reported for work at 8:00 a.m., his regular starting time. Gross was assigned to the utilities crew, a job he had done previously. Thomas Crowley (victim) was assigned to haul ore. Because of mechanical problems with his vehicle, Crowley was sent to assist Gross in loading pipe on a truck at the No. 2 shaft. Gross and Crowley worked at this assignment throughout the morning without known unusual incident.
At about noon, the two miners went to the TR3955 access drift on the 1550 level to finish connecting an air line and water hose to the pipe which had been previously installed. They worked from the deck of the scissors lift vehicle. After completing the installation, Gross saw that the valve handle at the end of the air hose could not be operated as installed unless it was turned. They began to loosen the valve assembly so that it could be rotated to the proper position. During the process, Crowley noticed that the coupling connecting the hose nipple to the valve was not properly seated in the groove. The two miners were loosening the coupling so the valve could be repositioned when the coupling, nipple, and air hose assembly blew away from the valve, whipping the hose and striking the two men.
Matthew Hatfield, miner, who was working in a drift nearby, heard the noise and ran to the site. He was unable to turn off the air to the whipping hose until it became wedged. Other miners working in the area arrived shortly and administered medical assistance to Gross and Crowley while they were en route to the surface. They were transported to a local hospital where Gross was pronounced dead at 5:28 pm. Death was attributed to massive head trauma. Crowley was treated for cuts and abrasions and released.
The cause of the accident was failure to bleed the pressure from the air line before conducting repairs. Failure to install automatic shutoff valves, safety chains, or other suitable locking devices between the hose and coupling was a contributing factor.
Order No. 7967701 was issued on February 16, 1999, under the provisions of Section 103(k) of the Mine Act:
The mine has experienced a fatal accident at the 1550 ramp - 3955 intersection while installing a compressed air line. This order is issued to insure the safety of any person in the mine until MSHA determines that the affected area can be returned to normal operation. The operator shall obtain approval from an authorized representative of the secretary for all actions to recover persons, equipment, and/or restore operations in the affected area. The mine operator is allowed to remove explosives in the affected area.This order was terminated on February 18, 1999, after it was determined that the area was safe and the mine could resume normal operations.
Citation No. 7966723 was issued March 4, 1999, under the provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 57.13021:
One underground miner was fatally injured and another seriously hurt on February 15, 1999, when a high pressure air hose separated from a coupling. The miners were adjusting the coupling on the pressurized hose when the hose came off and struck them. Automatic shutoff valves, safety chains, or other suitable locking devices were not used at the high pressure connection between the hose and coupling. The mine operator's failure to require and ensure that one or more of these safety devices were installed is a lack of reasonable care constituting more than ordinary negligence and is an unwarrantable failure to comply with a mandatory standard.This citation was terminated on March 18, 1999 after safety chains were installed on the connection between the four-inch hose and air line and elsewhere in the mine.
Citation No. 7966724 was issued on March 4, 1999, under provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 57.13019:
One underground miner was fatally injured and another seriously hurt on February 15, 1999, when a high pressure air hose separated from a coupling. The miners were adjusting a coupling on the pressurized hose when the hose came off and struck them. The mine operator's failure to require and ensure that the hose was not pressurized prior to work being performed is a lack of reasonable care constituting more than ordinary negligence and is an unwarrantable failure to comply with a mandatory standard.This citation was terminated on March 18, 1999 after all employees were retrained in proper procedures for repairs involving pressure systems and depressurizing compressed air lines prior to performing repairs.
1. List of persons present during the accident investigation
2. Typical air system components at Turquoise Ridge Mine
Related Fatal Alert Bulletin:
Persons participating in the investigation
Getchell Gold Corporation
Patrick Allen ............... loss control managerJackson & Kelly, PLC
Randy McFatridge ............... mine foreman
Brian Simmons ............... mine superintendent
Karen L. Johnston ............... attorney at lawState of Nevada, Mine Safety and Training Section
Cindy L. Hartman ............... mine inspectorMine Safety and Health Administration
James O. Frei ............... mine inspector
James Ploughman ............... supervisory mine safety and health inspector
David Kerber ............... mine safety and health inspector
Dennis Ferlich ............... mechanical engineer