DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
Metal and Nonmetal Mine Safety and Health
REPORT OF INVESTIGATION
Underground Metal Mine
Fatal Powered Haulage Accident
January 9, 2001
Newmont Mining Corp.
Carlin, Eureka County, Nevada
ID No. 26-02271
Michael S. Okuniewicz
Supervisory Mine Safety and Health Inspector
Terry D. Power
Richard M. Wilson
Mine Safety and Health Inspectors
Eugene D. Hennen
Juan L. Wilmoth
Mine Safety Specialist (Training)
Mine Safety and Health Administration
Rocky Mountain District
P.O. Box 25367, DFC
Denver, CO 80225-0367
Thomas J. Scott, miner 1, age 30, was fatally injured on January 9, 2001, when he backed the water truck he was operating into an open stope.
The accident occurred because a berm or bumper block had not been provided at this dump location.
Scott had a total of 7 years mining experience, 9 months as an underground miner, at this mine. Scott had not received his complete training in accordance with 30 CFR, Part 48.
The Carlin Mine, a multi-level, underground, gold mine, owned and operated by Newmont Mining Corp., was located 22 miles north of Carlin, Eureka County, Nevada. Principal operating officials were Jim Mullin Sr., vice president, North American operations; William Miles, director of health and loss prevention; Scott Santti, mine manager; Tim Burns, loss control supervisor; Joe Driscoll, mine superintendent; and Scott Robertson, mine supervisor. The mine normally operated two, 10 1/2 hour shifts a day, seven days a week. The mine employed 120 persons; of this number 100 persons worked underground.
Gold-bearing ore was drilled and blasted in open stopes, then transported on haulage trucks to the surface. The mined out stopes were backfilled with a wet mixture of waste rock and cement. The gold-bearing ore was stockpiled on the surface then transported off mine property to a milling and processing facility.
The last regular inspection of this operation was completed on November 11, 2000. A regular inspection was conducted after this investigation.
DESCRIPTION OF THE ACCIDENT
Thomas Scott (victim) reported for work at 7:30 a.m., his regular starting time. Scott was assigned by Mich Wood, leadman, to operate the water truck and wet roadways at the underground work areas. There was no set pattern in wetting down the haulage roadways in the mine. Work proceeded normally until about 10:30 a.m., when Scott talked to George Carlson, surface backfill batch plant operator, and was instructed to go back to the 5520 level 237 stope area where backfilling of the stope was in progress, and wet the area down again. Upon arriving at the 5520 level, Scott backed the water truck from the main haulage drift into the 237 stope and traveled over the dump location into the open stope.
There were no eye witnesses to the accident.
Scott was found at about 10:50 a.m., by Bob Riley and Brad Riches, surveyors, while they were starting to survey the brow of the stope. As they approached the edge they heard a warning buzzer sounding from inside of the stope, as they looked over the edge they saw the truck. Riches stayed on the 5520 level to guard the 237 stope area while Riley went to notify Mich Wood of the accident. Wood in turn notified George Carlson directing him to call for an ambulance. Wood called EMT Allen Rowe, then traveled to the bottom of the stope on the 5475 level, picking up EMT Randy Crawford en route. Wood, Rowe and Crawford then entered the stope. As they approached the cab of the truck, they did not see Scott, but found him down at the bottom of the backfill on the floor of the stope. Randy Crawford checked Scott for vital signs, but found none.
The County Sheriff arrived a short time later and Scott was pronounced dead. He was then transported to a funeral home in Elko, Nevada at 2:10 p.m.. Death was attributed to blunt force trauma.
INVESTIGATION OF THE ACCIDENT
MSHA was notified at 11:45 a.m., on the day of the accident by a telephone call from Tim Burns, loss control supervisor, to Richard Wilson, mine safety and health inspector. An investigation was started on the same day. MSHA's accident investigation team traveled to the mine and conducted a physical inspection of the accident site. The team interviewed a number of persons, reviewed documents relative to the job being performed by the victim along with his training records. An order was issued pursuant to Section 103(k) of the Mine Act to ensure the safety of miners. A representative of the miners was present during the investigation interviews.
The accident occurred at the 5520 level 237 stope. The drift had been driven at 0% grade and was about 20 feet wide and 14 feet high and extended 120 feet off the main haulage drift. This drift was developed directly above another drift on the 5475 level. Long holes connecting the two drifts were drilled and blasted. The distance from the dump point of the 237 stope to its lowest level was 60 feet. Broken rock was loaded from the 5475 level and hauled to the surface with a fleet of Wagner underground haul trucks ranging from 16 to 26 ton capacity. Observations indicated no instability of the drift floor at the dump point were the water truck went over the edge.
At the time of the accident, waste rock mixed with cement was being dumped at the edge of the 237 stope to backfill the mined-out area. Reportedly, at 2:00 a.m., during the shift prior to the accident, a four-foot berm of backfill material had been built at the dump point of the 237 stope. At about 9:00 a.m., after the start of the next shift, the first haul truck driver bringing backfill material to this location found no berm. After dumping his load over the edge he directed the second driver to inform the supervisor that the berm was missing. The third truck driver met with the leadman and the jammer operator and built a new berm.
When the investigators arrived at the scene, a berm of backfill material consisting of 2 inch minus waste rock and cement was present at the edge of the stope and averaged from 16 inches to 28 inches high across the drift. This material was not cured and was still soft to the touch. The company stated that this material required 36 hours to cure. This was the typical method of berming at the edge while backfilling the mined-out open stope. There were no tracks to indicated the water truck traveled through or over this berm. The investigation determined that backfill material had been dumped on the water truck after it traveled over the dump point.
The vehicle involved in the accident was a four-wheel drive Getman A-64 water truck, Serial No. 6458. The truck was powered by a 4-71 TI Detroit Diesel engine coupled with a Clark 2800 transmission, which had three speeds in both forward and reverse. This machine had an articulated chassis and was about 24 feet long, 7 feet wide, and 7 feet high with a 1,500 gallon water tank mounted on the rear section of the machine. The front section of the machine contained the operator's compartment with the engine and transmission mounted behind the operator's compartment. The weight of the empty machine was approximately 20,400 pounds. The weight of the fully loaded machine was approximately 32,000 pounds. The average height of the tires used on the mobile equipment at this mine was 42 inches.
The truck had two braking systems, a parking brake system and a service brake system. The service brakes were hydraulically applied wet disk brakes internal to both axles. The service brakes were applied by a foot pedal. The foot pedal controlled hydraulic pressure to two separate hydraulic systems, one for each axle. This provided secondary service braking in the event of a failure in either system. The parking brakes were spring applied and hydraulically released. The park brakes were controlled by a dash mounted push-pull hand control. The parking brakes were integral to the service brake system using the same brake components as the service brakes to generate parking brake force on the front and rear axles. After the recovery of the machine, the park brake control was found in the "off" position (pulled out).
The brake force of both the service brake and park brake was checked by performing a drawbar pull test. The water tank was filled and the brakes were applied. The braking force was measured using a tension link type load cell. The pull tests conducted revealed that the fully applied service brake produced a braking force of 16,000 pounds and the park brake produced a braking force of 6,000 pounds. The forces determined during the brake test were used to calculate the approximate grade holding ability of the brake systems. The calculations revealed that the service brake produced enough braking force to hold the loaded truck on a 56% grade and the park brake produced enough force to hold the loaded truck on an 18% grade.
No defects were found with the service brake system.
In addition to the pull test, the loaded truck was placed on a 13% grade to further test the park brake. The park brake would not immediately hold the machine on the 13% grade. There was an approximate 1 1/2 second delay after the park brake was applied before enough braking force was generated to hold the machine on the 13% grade.
The brake adjustment procedure in Getman's maintenance manual consisted of applying a brake release pressure of 1,000 psi, tightening the wheel cylinder adjuster nut to 50 inch-pounds and then backing the nut off 1 1/2 turns. Since the wheel cylinders supplied the braking force for both the service brake and the park brake, this adjustment procedure adjusted both the service and park brake systems. Personnel from Getman's engineering department stated the park brake is fully released at 137 psi and the wheel cylinder's maximum working pressure rating was 3,000 psi. These facts revealed the brake adjustment procedure was valid for any release pressure between 137 and 3,000 psi.
The machine's park brake release pressure of 2,050 psi was applied to fully release the park brake and the location of the adjuster nuts were checked for each of the wheel cylinders. This check revealed the adjusting nut for the left rear wheel cylinder was 6 1/8 turns loose and the right rear wheel cylinder was 7 1/4 turns loose. The check also revealed the adjusting nuts on the front wheel cylinders were loose with the right side being 8 7/8 turns loose and the left side being 7 7/8 turns loose.
All of the adjusting nuts were looser than the 1 1/2 turns specified by the manufacturer and therefore were significantly out of adjustment. After the brakes were adjusted, the test was repeated and the park brake would hold the loaded truck on the 13% immediately after it was applied.
The seat in the water truck had been replaced with a different type of seat than had originally been provided by the truck manufacturer. The seat in the truck at the time of the accident was a Vanguard Model seat manufactured by Seat Incorporated on February 2, 2000. The Part No. on the seat was 148636VN01 and the Serial No. was VG1815. The seat was shipped to Newmont Gold Mining Corp. without a seatbelt. The seat in the truck at the time of the accident originally had a suspension which allowed the seat to move up and down as the truck travel through rough areas. By the time of the accident, a long bolt had been welded between the seat's bottom mounting frame and the bottom of the seat pan to prevent the seat suspension from moving.
During the investigation, it was revealed that the seatbelt the operator had worn tore loose from its mounting on the right side where the webbing was fastened to the right side anchor plate. The two sections of the seatbelt attached to the seat were removed for further evaluation. The seatbelt was sent to Touchstone Research Laboratory, Triadelphia, West Virginia, for evaluation of the failed sections by electron and optical microscopy. This evaluation revealed that approximately 87% of the webbing at the right side failure location had failed due to abrasion which indicated the belt was severely worn at the time of the accident.
MSHA's regulations do not require seatbelts to be provided or worn by operators of underground equipment.
The water truck had two headlights on both the front and rear. These lights were controlled by separate rotary switches and found to be operational at the time of the accident.
The water truck was shipped from the manufacturer with a rear mounted spray bar with six nozzles. A water pump driven by a hydraulic motor supplied water to the nozzles. The hydraulic motor to drive the water pump was controlled by a diversion valve operated by a manual control located to the right of the operator. By the time of the accident, the six nozzles had been replaced by one large water sprayer located in the center rear of the truck and a spray bar with two nozzles. One of the two nozzles was located on each side of the rear of the machine. The manually operated diversion valve used to control the hydraulic motor which drives the water pump was replaced by an electrical operated diversion valve. The control for this diversion valve was found in the off position. When the diversion valve is off, the water spray or nozzles are not being used.
The operator's compartment was equipped with a canopy by the truck's manufacturer. The manufacturer stated the canopy had been ordered as a non-certified canopy and did not meet any of the Society of Automotive Engineers' standards for either a falling object or a rollover protective structure. The canopy was severely damaged in the accident and a weld on the middle of the canopy's front support member failed. Although the canopy was severely damaged in the accident, the volume inside of the operator compartment changed very little as a result of the accident.
The geometric design of the machine and the location of the operator created severe blind areas for the operator, including the entire right side and the rear areas of this machine. An operator of this machine could see part of the area immediately behind the machine only if the rear of the machine was articulated away from the operator. These blind areas would have made it difficult for the operator to see the condition of the berm as he backed into the drift.
There were no defects on the Getman water truck that were determined to have caused or contributed to the cause of the accident.
A review of the company's Part 48 training records indicated that the victim had not completed all the required courses included in the company's approved plan for Training of New Miners before he was assigned to underground work duties. The documentation showed the victim had received task training regarding the operation of the water truck on July 8, 2000.
The cause of the accident was the failure to maintain a berm, bumper block, or impeding device at the stope's dumping location. The driver's restricted visibility while backing into the drift was a contributing factor.
Order No. 7944854 was issued on January 9, 2001, under the provisions of Section 103(k) of the Mine Act:
A fatal accident occurred at this operation on January 9, 2001, when a truck operator was wetting down the road way in the 5520 level 237 stope. The water truck operator backed over the berm in front of the stope they were backfilling. This order is issued to assure the safety of persons at this operation until the mine or affected areas can be returned to normal operations as determined by an authorized representative of the Secretary of Labor. The mine operator shall obtain approval from an authorized representative for all actions to recover equipment, and\or return areas of the mine to normal operations.
This order was terminated on January 16, 2001, after it was determined that this area of the mine could resume normal operations.
Citation No. 7907245 was issued on January 30, 2001, under the provisions of 104(a) of the Mine Act for violation of 57.9301:
On January 9, 2001, a fatal accident occurred at this mine when a miner backed a water truck into an open stope on the 5520 level 237 stope. Berms, bumper blocks, or similar impeding devices were not provided at the edge of the open stope. It was determined that haul trucks dumped material at the edge of this dump location when an adequate berm was not in place.
This citation was terminated on January 31, 2001, when the company installed a berm and a truck spotter at this location and re-instructed miners not to use dump locations unless impeding devices were in place.
Related Fatal Alert Bulletin:
Persons Participating in the Investigation
Newmont Mining Corp.
William G. Miles .......... Director of Health and Loss Prevention
State of Nevada, Mine Safety & Training Services
Timothy Burns .......... Loss Control Supervisor
Scott Santti .......... Mine Manager
Peter Johnstone .......... Maintenance Supervisor
Joe Driscole .......... Carlin East Superintendent
Jim Christensen .......... Miners' Representative
Joseph N. Rhoades .......... State Mine Inspector
Mine Safety and Health Administration
Kenneth Curtis .......... State Mine Inspector
Michael S. Okuniewicz .......... Supervisory Mine Safety and Health Inspector
Terry D. Power .......... Mine Safety and Health Inspector
Richard M. Wilson .......... Mine Safety and Health Inspector
Eugene Hennen .......... Mechanical Engineer
Juan L. Wilmoth .......... Mine Safety Specialist (Training)
Newmont Mining Corp.
Scott Santti .......... Mine Manager
Scott Robertson .......... Supervisor
Mich Wood .......... Leadman
Bob Riley .......... Surveyor
Brad Richens .......... Surveyor
George Carlson .......... Batch Plant Operator
Gaylan Eisenbarth .......... Miner III
Marco Bajovich .......... Miner III
Danny Green .......... Miner III
Kyle Hirsh .......... Supervisor
Randy Crawford .......... Miner III/EMT
Alan Rowe .......... Miner III/EMT
Greg Atonie .......... Miner III
George Lauver .......... Miner I