DEPARTMENT OF LABOR
MINE SAFETY AND HEALTH ADMINISTRATION
Western District
Metal and Nonmetal Mine Safety and Health
ACCIDENT INVESTIGATION REPORT
SURFACE METAL MINE
FATAL FALL OF MATERIAL ACCIDENT
Crofoot/Lewis Mine and Mill [I.D. No. 26-01962]
Hycroft Resources & Development, Inc.
Winnemucca, Humboldt County, Nevada
January 12, 1995
By
Ronald M. Mesa
Mine Safety and Health Inspector
Robert Morley
Mine Safety and Health Inspector
Western District Office
3333 Vaca Valley Parkway, Suite 600
Vacaville, CA 95688
Fred M. Hansen, District Manager
GENERAL INFORMATION
Daniel J. David, a 23 year old powderman, was fatally injured January 12, 1995, while off-loading ammonium nitrate/fuel oil, ANFO, from a vertical storage bin into a delivery truck. The victim had 3 1/2 years of mining experience, two months as a powderman at this operation.
Gary Frey, MSHA Reno Field Office Supervisor, was notified of the accident by Lee Morrison, Human Resources Director, Hycroft Resources & Development, Inc. Notification was made January 12, 1995, at approximately 2:30 p.m. An investigation was started the same day.
The accident occurred at the Crofoot/Lewis Mine and Mill which was owned and operated by Hycroft Resources & Development, Inc. The operation was located 51 miles west of Winnemucca, Humboldt County, Nevada. There were 255 employees who worked one of two 10 1/2 hour shifts, 6 days a week.
At the Crofoot/Lewis Mine, drilled and blasted gold ore was loaded into 150 ton 785B Caterpillar haul trucks, by a 1800 Hitachi track mounted shovel with a 14 yard bucket, and transported to the crusher. The ore was then crushed, screened, and milled. This multiple bench mine had an average daily production of 100,000 tons of gold bearing ore.
Principal officials for Crofoot/Lewis Mine were:
Paul Wright, General Manager
John Nachiondo, General Mine Foreman
Fred Leonard, Mine Operations Manager
Lee Morrison, Human Resources Director
Records indicated that training required by 30 CFR, Part 48, was conducted in accordance with the company's MSHA approved training plan. The plan was last updated July 5, 1988.
The last regular inspection was completed August 18, 1994.
Information for this report was obtained by visiting the
accident site and interviewing employees and officials of the
company.
PHYSICAL FACTORS INVOLVED
The accident occurred north of the main plant at the lower prill bin, one of the explosive magazine areas at the mine. The lower prill bin was used to store ANFO. The overall capacity of the tank was 115,000 pounds. At the time of the accident it contained approximately 82,000 pounds.
During the winter months moisture in the air caused the ANFO to adhere to the storage bin and to itself. Laborers used 10 pound hammers to jar the sides and cone section of the bin and loosen the contents.
The Model T800B ANFO Delivery Truck, VIN INKDLEEX8RR6188959, was manufactured by Worthen Kenworth, Inc., Sparks, Nevada. It bore the company designation ME-42. The truck was a three axle, ten wheeled vehicle measuring 22 feet 3 inches in length and 8 feet 1 inch in width. It was fitted with a three compartment bin manufactured by Aresco, Inc., Post Falls, Idaho. The bin measured 18 feet in length, 6 feet 3 inches in height, and had a capacity of 30,600 pounds. Hycroft Resources had installed handrails on top of the truck.
The lower prill storage bin contained ANFO used for loading the pit blasts. The bin was on the mine site when Hycroft Resources purchased the mine in 1986. There were no manufacturer's signs, markings, or serial numbers that might have helped identify the structure. It was built in three parts; a nine foot cone roof attached to an eight foot cylinder, with an inverted 9 foot cone containing the off-loading port. The inverted bottom cone section was attached to the cylinder section with 100 bolts, to the supporting structure with 20 bolts. The bolts were of low to medium carbon steel, SAE grade two, 3/4 inch in diameter, 10 threads per inch, no AFASTM markings, and had indented hex heads. The lower prill bin was mounted on four 24 gauge I-beam steel columns. The I-beams were 20 feet by 8 inches by 8 inches.
The columns were connected by two 16 feet, 12 inch by 12 inch, 58 gauge steel I-beam girders. The girders were connected by two 12 feet, 12 inch by 12 inch, I-beams of 35 gauge steel. There were 10 vertical structure members welded to the girders and beams.
The deck was constructed of 1 inch steel grating and was welded to 6 inch angle iron.
During the accident investigation, blasting crew members stated they had reported to the general mine foreman, on January 6, 1995, that there were three or four bolts missing on the south side of the bin. Crew members stated that they had stuffed rags in the holes and then sprayed over them with pressurized foam.
The general mine foreman responded that the bolts had been missing for over two years and the crew had stuffed rags in the holes. The foreman said that on January 6, 1995, the crew removed the rags in order to spray foam over the holes.
Pre-shift inspection reports, completed by the blasting crew for January 1995, showed no major safety defects on the ANFO delivery truck. The blasting crew had not been submitting a pre-shift inspection report for each shift because company policy stated that the crew was to submit a daily report. There is no MSHA standard that requires a report to be submitted daily unless there is a defect that affects safety.
Interviews with blasting crew members revealed that daily examinations of the lower prill bin working area were not being conducted, and there were no company records to suggest otherwise. The leadman for the blasting crew did not examine the work area on the day of the accident. The company did provide records that the other sections of the mine were examined on a daily basis.
All applicable training for Daniel David was current including
new hire, annual refresher, and task.
DESCRIPTION OF ACCIDENT
Daniel J. David, powderman, began his shift at 7:00 a.m., January 12, 1995, his regular starting time. David was assigned the task of operating ME-92, a 1993 Kenworth ANFO delivery truck. The blasting crew finished loading a shot in the pit and blasted it just before lunch. Following lunch, Vern Steier, Leadman, instructed David to take the ANFO truck to the lower prill bin and load it in preparation for the next day's work. As David was driving down the ramp leading into the storage area he encountered co-workers Tyler Seal and James Williamson. David told them of the duties assigned by Steier and the three men then proceeded to the lower bin area. David positioned the ANFO truck under the bin, climbed up onto to the truck, and started to unload ANFO from the bin. At this time, the front compartment was partially full and the middle and the back were empty.
The procedure for loading the ANFO truck was for one employee to stand on top of the truck and operate the chute handle while another employee drove the truck forward. The three compartments would then be filled, front to back. David began loading the truck but the ANFO stopped flowing. He took a 10 pound hammer, kept on top of the truck, and banged on the chute portion of the bin. The ANFO started flowing but again stopped. He repeated the procedure with the same results. David then closed the chute door. Seal said he would climb up to the deck and hammer on the conical section above the chute.
Williamson said he should go instead as he had not been task trained to operate the truck. Seal agreed and started back down the ladder. He was about ground level when there was a loud noise and ANFO began flowing everywhere. It was about 2:15 p.m. Seal and Williamson both ran from the bin, returning when it appeared everything had stopped moving. They then went around the front of the ANFO truck, looking for David. They saw that he was pinned by the cone section and the deck grating against the handrails on top of the truck. They then used the truck radio to call for help.
First responders arriving on the scene were unable to detect any life signs. The body was extracted, placed in the mine's emergency vehicle and transported. Ten miles from the mine, the coroner and an ambulance met the emergency vehicle. David was pronounced dead and delivered to an Elko, Nevada funeral home.
The Humboldt County Sheriff's Office concluded that death
resulted from traumatic injuries.
CONCLUSION
Prior to the accident the bin contained approximately 82,000 pounds of ANFO. The material was hung up, or bridged, preventing it from flowing out of the bin. Following initial attempts to loosen the material, it abruptly fell onto the inverted cone section. The sudden impact resulted in an instantaneous shearing of the 20 bolts connecting the upper and lower portions with the vertical structure members. This sudden impact also caused the 100 other connecting bolts to pull through the sheet metal. The inverted cone section and the deck fell on top of the ANFO truck pinning David against the handrails.
Order No. 4140022, 103(k), Issued on 01/12/95
A fatal accident occurred when an employee was crushed by the inverted cone section and deck of a ANFO storage bin.
This order prohibits any work on or around the bottom prill tank except what it takes to get the injured person out. The prill tank is to remain unchanged so an investigation into the possible cause can be conducted. This is in effect until the order is terminated.
Respectively submitted by:
/s/ Ronald M. Mesa
Mine Safety and Health Inspector
/s/ Robert Morley
Mine Safety and Health Inspector
Approved by:
Fred M. Hansen,
District Manager
Related Fatal Alert Bulletin:
[FAB95M03]