MINE SAFETY AND HEALTH ADMINISTRATION
ROCKY MOUNTAIN DISTRICT
Metal and Nonmetal Mine Safety and Health
Surface Nonmetal Mine
(Uranium)
Fatal Powered Haulage Accident
Pronghorn Drilling Company
ID No. N5Y
at
Smith Ranch Project
Rio Algom Mining Corporation
Douglas, Converse County, Wyoming
ID No. 48-00837
September 16, 1999
by
Tyrone Goodspeed
Supervisory Mine Safety and Health Inspector
Joseph O. Steichen
Mine Safety and Health Inspector
Dennis Ferlich
Mechanical Engineer
Jeffrey J. Ream
Civil Engineer
Originating Office
Mine Safety and Health Administration
Rocky Mountain District
P.O. Box 25367, DFC, Denver, CO 80225-0367
Claude N. Narramore, District Manager
OVERVIEW
Philip L. Robidoux, water truck driver, age 37, was fatally injured at about 10:30 a.m., on September 16, 1999, when he lost control of the truck he was driving and crashed into a ravine. He lost control of the truck because it was not maintained in safe operating condition.
Robidoux had a total of one year, seven months mining experience, the past year and six weeks as a water truck driver at this operation. He had received training in accordance with 30 CFR, Part 48.
GENERAL INFORMATION
The Smith Ranch Project, an in-situ leaching operation, owned and operated by Rio Algom Mining Corporation, was located at Douglas, Converse County, Wyoming. The principle operating official was William F. Ferdinand, site manager. The mine was normally operated two, 8-hour shifts a day, five days a week. Total employment was 78 persons.
Uranium was leached out of the ore body by a system of injection and retrieval wells. The resulting liquid was pumped to a processing plant, where the uranium was extracted. The finished product was shipped to a converter facility for use in nuclear power generation.
The victim was employed by Pronghorn Drilling Company, located at Glenrock, Wyoming. The principle operating official was Robert E. Taylor, owner. Robidoux was employed at a branch facility located at Douglas, Wyoming. Total employment at the Douglas facility was six persons. Pronghorn Drilling Company was one of several contractors on-site to drill well fields for the mining company.
The last regular inspection of this operation was completed on January 7, 1999. Another inspection was conducted in conjunction with this investigation.
DESCRIPTION OF THE ACCIDENT
On the day of the accident, Philip Robidoux (victim) reported for work at 6:00 a.m., his normal starting time. He worked briefly at the well field and then drove the water truck onto the access road, up the slope following the road along the ridge top and filled his truck at the water storage tank. He then turned around, traveled back across the top of the ridge and stopped to pick up his lunch pail before following the road back down the slope. The drill crew noticed that the truck was not slowing down as it should in order to make the turn into the well field. The truck left the road at the curve at the bottom of the slope and traveled across a storm water diversion ditch. From there the truck traveled through the grass, bouncing as it went, for a distance of approximately 400 feet. The truck eventually came to rest in a gully. The frame of the truck broke just behind the cab, which allowed the truck to fold. As the truck folded, the cab was crushed by the water tank, which was still mounted to the rear of the chassis.
Witnesses notified company officials and checked the victim for vital signs. Mining company officials arrived on the scene moments later along with an emergency medical technician. They checked for signs of life and found none. Local emergency medical personnel arrived a short time later and Robidoux was pronounced dead at the
scene by the county coroner. Death was attributed to crushing trauma to the chest.
INVESTIGATION OF THE ACCIDENT
MSHA was notified at 12:43 p.m., on the day of the accident by a telephone call from Terry W. Warner, supervisor, administration & personnel for the mining company, to Danny Frey, mine safety and health inspector. An investigation was started the next day. MSHA's investigation team traveled to the mine and made a physical inspection of the accident site, interviewed a number of persons, and reviewed documents relative to the job being performed by the victim and his training records. An order was issued pursuant to section 103(k) of the Mine Act to ensure the safety of miners. The miners did not request, nor have, representation during the investigation.
DISCUSSION
The accident occurred on an access road to the well field where Pronghorn Drilling Company was working. The road was 20 to 24 feet wide with a surface of compacted well-graded crushed rock ranging in size from gravel to sand. It was crowned slightly in the center to promote drainage to both sides. The grades of the road ranged from 3% near the bottom curve, to approximately 10% for a length of 1,000 feet from near the middle of the slope to the top. The victim traveled approximately 1/4-mile across the ridge from the water tank to the location where he picked-up his lunch pail at the top of the access road, then approximately 1/2-mile down the slope to the curve where the truck left the road.
The water truck involved in the accident was a 1978, Mack Super Liner, 10-wheel tandem cab and chassis with approximately a 4,000 gallon water tank measuring approximately 21 feet long by 75 inches in diameter. The chassis was a two-piece frame consisting of a single aluminum channel beam construction from the cab front mounting brackets to the rear and a single steel channel beam frame construction forward of the cab front mounting brackets. The aluminum truck frame was constructed of aluminum channel beam 10-1/2 inches deep with 3-1/2 inch flanges. The flange thickness was approximately 7/8-inch and the web thickness was approximately 1/2-inch thick. As a result of the accident, the frame was broken through both rails and separated between the cab and the water tank. The break occurred through the bolt holes where the cross members fastened to the left and right frame members.
The total GVWR of the truck was 46,000 pounds. The front suspension was rated at 12,000 pounds and the rear suspension was rated at 34,000 pounds (17,000 pounds per rear axle). The wheel base width (outside tire dimension) was approximately 96 inches and the wheel base length was approximately 242 inches as measured from the approximate centerline of the steering axle to the centerline of the rear bogie.
The engine was a Cummins, Model NTC-290, six-cylinder, turbo- charged diesel engine, S/N 10950656, rated at 290 hp at 2,100 rpm. The engine included a Jacobs Engine Brake. The engine brake could be turned on/off by one toggle switch and placed in three positions by a second panel switch. Position 1 activated 6 cylinders for the greatest amount of braking; position 2 activated 4 cylinders for less braking, and position 3 activated 2 cylinders for the least amount of braking. When in the on position, the engine brake was controlled through electrical solenoids via the clutch pedal or throttle pedal. The Mack build specifications for this truck show that it was manufactured with a Cummins, Model NTC-400 diesel engine, S/N 10764941, not the Cummins, Model NTC-290.
The transmission was an Eaton Fuller Road Ranger, Model RTO12513, manual 13-speed transmission, controlled by a single gear shift lever with a single 3-position switch on the shift knob for selection of low, direct, and overdrive speed ranges. Following the accident the transmission shift lever appeared to be in neutral as determined by easy sideways movement. Later in the investigation, it was confirmed that the transmission was in neutral position by removing the transmission top cover plate and inspecting the position of the gear selector slots.
The steering was a mechanical gear box with hydraulic assist. Emergency steering was not included.
The brake system consisted of 4 air-applied S-cam actuated drum type service brakes, with brakes on each side of the two rear drive axles. The brake components had been removed from the front steering axle. A spring applied, air pressure released parking brake, which was integral to the service brakes, was present on all 4 brakes on the two drive axles. The service brakes could be applied using a foot brake pedal. The parking brakes could be applied manually with the parking brake valve in the operator's cab or automatically from loss of air system pressure. The air chambers on the two rear drive axles were Type 30. The Mack build specifications for this truck show that it was manufactured with a Rockwell FF9311-C front axle that designates cam brakes.
Components damaged in the accident were replaced and/or bypassed to test the leakage rate of the braking system in accordance with the test specifications in the Mack Air Brake System Manual. The Mack manual specifies a maximum leakage rate of 2 psi/minute without the service brakes applied, and a maximum leakage rate of 3 psi/minute with the service brakes applied, with the engine stopped. The braking system leakage rate exceeded these specifications. Without the service brakes applied the average leakage rate was 25 psi/minute. Severe air leakage was found at the exhaust port of the relay valve located in the frame above the left forward drive axle brake. Disassembly and visual examination showed that the exhaust valve spring was corroded (rusted) and broken. The broken spring failed to provide the spring force required to seat the valve, allowing constant leakage from the relay exhaust port. Based on the corrosion on the spring and the corrosion on the area of the break, it was determined that this was a pre-existing condition.
During the tests, the parking control knob engaged (popped out) at 16 psi which was below the 40 +/- 5 psi specified in the Mack Air Brake System Manual. This condition compromised the effectiveness of the braking system, allowing the service brake pressure to drop to 16 psi before the spring brakes fully applied. The spring brakes began pushing against the brake drum at 32 psi, as noted by hand turning the wheel while decreasing air system pressure. At 32 psi, the wheel was hard to turn by hand, but the parking brakes were not fully set, as noted by watching continued movement of the adjuster/pushrod until after the parking control knob popped out at 16 psi. The tests showed that the spring brakes began to apply at 32 psi, but full application was not available until the button popped out at 16 psi and released all of the pressure within the air chamber.
The pushrod travel of all brake chambers was measured with approximately 100 psi of air pressure supplied to the air chambers. The following conditions were found:
1. The pushrod stroke for the right forward drive axle brake exceeded the maximum specified pushrod stroke of 2 inches for Type 30 air chambers. The pushrod stroke measured 2-5/16 inches.
2. The pushrod stroke for the left forward drive axle brake exceeded the maximum specified pushrod stroke of 2 inches for type 30 air chambers. The pushrod stroke measured 2-7/16 inches.
The right rear drive axle adjuster and the left rear drive axle adjuster were reportedly turned to release the brakes during rescue efforts. The measured strokes for these brakes were 2-3/8 inches, which exceeded the maximum specified pushrod stroke of 2 inches for Type 30 air chambers. However, the measurements are not representative of the strokes at the time of the accident.
All of the brakes were disassembled, visually inspected, and measured. The following results were obtained:
1. Right Rear Drive Axle Brake: The brake drum wear surface was shiny and clean in appearance indicating lining to drum contract, but the surface had numerous heat checks and was severely scored. The brake drum diameter exceeded the maximum wear diameter of 16.620 inches stamped on the drum. The brake drum measured 16.684 inches diameter at the largest un-scored dimension, or 0.064 inches oversize. In the scored areas, the brake drum measured 16.755 inches diameter at the largest dimension, or 0.135 inches oversize. The brake linings were clean with no cracks or missing pieces and measured 3/8-inch thick. A tip of the S-cam was broken, but not in the area of normal contact with the roller. No end play, as determined by feel, was found in the S-cam shaft. The rollers and springs were in acceptable condition with no visible signs of wear. The braking force generated by this brake was compromised by a combination of the oversize drum and the braking system air leak through the faulty relay valve. The pushrod slack adjusters were reportedly turned to disengage the spring brakes prior to this investigation, so it is unknown if excessive pushrod stroke additionally compromised the braking force generated by this brake.
2. Left Rear Drive Axle Brake: The brake drum wear surface was shiny and clean in appearance indicating lining to drum contact, but the surface had numerous heat checks and was severely scored. The brake drum diameter exceeded the maximum wear diameter of 16.620 inches stamped on the drum. The brake drum measured 16.709 inches diameter at the largest non-scored dimension, or 0.089 inches oversize. In the scored areas, the brake drum measured 16.749 inches diameter at the largest dimension, or 0.129 inches oversize. The brake linings were clean with no cracks or missing pieces and measured 1/2-inch thick. The S-cam, rollers, and springs were in acceptable condition with no visible signs of wear and no end play as determined by feel. The braking force generated by this brake was compromised by a combination of the oversize drum and the braking system air leak through the faulty relay valve. The pushrod slack adjusters were reportedly turned to disengage the spring brakes prior to this investigation, so it is unknown if excessive pushrod stroke additionally compromised the braking force generated by this brake.
3. Right Forward Drive Axle Brake: The brake drum wear surface was shiny and clean in appearance indicating lining to drum contact, but the surface had numerous heat checks and was scored. The brake drum wear surface was discolored from overheating. The brake drum diameter exceeded the maximum wear diameter of 16.620 inches stamped on the drum. The brake drum measured 16.707 inches diameter at the largest non-scored dimension, or 0.087 inches oversize. In the scored areas, the brake drum measured 16.814 inches diameter at the largest dimension, or 0.194 inches oversize. The brake linings were clean with no cracks or missing pieces and measured 1/2-inch thick. The S-cam, rollers, and springs were in acceptable condition with no visible signs of wear and no end play as determined by feel. The braking force generated by this brake was compromised by a combination of the oversize drum, the excessive pushrod stroke, and the braking system air leak through the faulty relay valve.
4. Left Forward Drive Axle Brake: The brake drum wear surface was shiny and clean in appearance indicating lining to drum contact, but the surface had numerous heat checks and was scored. The brake drum diameter exceeded the maximum wear diameter of 16.620 inches stamped on the drum. The brake drum measured 16.681 inches diameter at the largest non-scored dimension, or 0.061 inches oversize. In the scored areas, the brake drum measured 16.761 inches diameter at the largest dimension, or 0.141 inches oversize. The brake linings were clean with no cracks or missing pieces and measured 5/8-inch thick. The S-cam, rollers, and springs were in acceptable condition with no visible signs of wear and no end play as determined by feel. The braking force generated by this brake was compromised by a combination of the oversize drum, the excessive pushrod stroke, and the braking system air leak through the faulty relay valve.
CONCLUSION
The accident occurred because the contractor failed to maintain the truck in safe operating condition. No brakes were present on the front (steering) axle. According to Mack's build specifications for this truck, front axle brakes were installed when the truck was built. All of the brake drums were oversize and severely scored, resulting in compromised braking force at all four brakes. Severe air leakage was found at the exhaust port of the relay valve supplying the brakes. The pushrod strokes for the right forward drive axle brake and the left forward drive axle brake exceeded the maximum allowable limit, compromising the braking force generated by these brakes. The parking control knob engaged (popped out) at 16 psi, which is below the 40 +/- 5 psi specified in the Mack Air Brake System Manual. Failure to wear the seat belt possibly contributed to the severity of the accident.
ENFORCEMENT ACTIONS
Pronghorn Drilling Company
Order No. 7917541 was issued September 16, 1999, under the provisions of Section 103(k) of the Mine Act:
A fatal accident occurred at this operation on September 16, 1999, when a contractor water truck driver was hauling a load of water downhill to the #16 drill rig. The driver sustained fatal injuries when the truck struck an earthen wall. This order is issued to assure the safety of persons at this operations until the mine or affected areas can be returned to normal operations as determined by an authorized representative of the Secretary. The mine operator shall obtain approval from an authorized representative for all actions to recover persons, equipment, and/or return affected areas of the mine to normal operations.This order was terminated September 20, 1999. Conditions that contributed to the accident have been corrected and normal mining operations can resume.
Citation No. 7918294 was issued October 19, 1999, under the provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 56.14101(a)(1):
A fatal accident occurred at this operation on September 16, 1999, when a contractor's employee lost control of a water truck and crashed into a ravine. The service brake system was not maintained in safe operating condition. The front (steering axle) brakes had been removed. The rear axle brake drums and linings were worn and out of adjustment. A relay valve in the system was leaking air. Failure of the contractor to maintain the truck's braking system in safe operating condition is a serious lack of reasonable care constituting more than ordinary negligence and is an unwarrantable failure to comply with a mandatory safety standard.This citation was terminated October 19, 1999. The truck has been scrapped and this contractor is no longer doing business at mine sites.
Order No. 7918295 was issued October 19, 1999, under the provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 56.14101(a)(2):
A fatal accident occurred at this mine on September 16, 1999, when a contractor's employee lost control of a water truck and crashed into a ravine. The parking brake was not capable of holding the truck on the inclined road where the accident occurred. The parking brakes were out of adjustment and the brake linings and drums were worn excessively. Failure to maintain the parking brake in safe operating condition is a serious lack of reasonable care constituting more than ordinary negligence and is an unwarrantable failure to comply with a mandatory safety standard.This order was terminated October 19, 1999. The truck has been scrapped and this contractor is no longer doing business at mine sites.
Order No. 7918296 was issued October 19, 1999, under the provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 56.14100(a):
A fatal accident occurred at this operation on September 16, 1999, when a contractor's employee lost control of a water truck and crashed into a ravine. The truck had not been adequately inspected for defects affecting safety prior to placing it in operation and safety defects had not been corrected. Failure of the contractor to assure that adequate inspections were conducted on the truck and failure to promptly correct safety defects is a serious lack of reasonable care constituting more than ordinary negligence and is an unwarrantable failure to comply with a mandatory safety standard.This order was terminated October 19, 1999. The truck has been scrapped and this contractor is no longer doing business at mine sites.
Order No. 7918297 was issued October 19, 1999, under the provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 56.14131(a):
A fatal accident occurred at this mine on September 16, 1999, when a contractor's employee lost control of a water truck and crashed into a ravine. He was not wearing the seatbelt provided in the truck. Failure of the contractor to assure that equipment operators wear seatbelts is a serious lack of reasonable care constituting more than ordinary negligence and is an unwarrantable failure to comply with a mandatory safety standard.This order was terminated October 19, 1999. The truck has been scrapped and this contractor is no longer doing business at mine sites.
Rio Algom Mining Corporation
Citation No. 7918226 was issued on October 19, 1999, under the provisions of Section 104(a) of the Mine Act for violation of 30 CFR 56.14101(a)(1):
A fatal accident occurred at this operation on September 16, 1999, when a contractor's employee lost control of a water truck and crashed into a ravine. The service brake system was not maintained in safe operating condition. The front (steering axle) brakes had been removed. The rear axle valve in the system was leaking air. Miners and employees of other contractors frequently used the access road where the accident occurred and could have been endangered by the runaway truck.This citation was terminated October 19, 1999. The truck has been scrapped and this contractor is no longer doing business at mine sites.
Citation No. 7918227 was issued October 19, 1999, under the provisions of Section 104(a) of the Mine Act for violation of 30 CFR 56.14101(a)(2):
A fatal accident occurred at this mine September 16, 1999, when a contractor's employee lost control of a water truck and crashed into a ravine. The parking brake was not capable of holding the truck on the inclined road where the accident occurred. The parking brakes were out of adjustment and the brake linings and drums were worn excessively. Miners and employees of other contractors frequently used the access road where the accident occurred and could have been endangered by the runaway truck.This citation was terminated October 19, 1999. The truck has been scrapped and this contractor is no longer doing business at mine sites.
Citation No. 7918228 was issued October 19, 1999, under the provisions of Section 104(a) of the Mine Act for violation of 30 CFR 56.14100(a):
A fatal accident occurred at this operation on September 16, 1999, when a contractor's employee lost control of a water truck and crashed into a ravine. The truck had not been adequately inspected for defects affecting safety prior to placing it in operation and safety defects on the truck had not been corrected. Miners and employees of other contractors frequently used the access road where the accident occurred and could have been endangered by the runaway truck. This citation was terminated October 27, 1999. The mine operator has reinforced its policies and requirements for compliance with each drill rig contractor and has conducted a verification audit with each drill rig contractor.Citation No. 7918229 was issued October 19, 1999, under the provisions of Section 104(a) of the Mine Act for violation of 30 CFR 56.14131(a):
A fatal accident occurred at this mine September 16, 1999, when a contractor's employee lost control of a water truck and crashed into a ravine. He was not wearing the seatbelt provided in the truck. Miners and employees of other contractors frequently used the access road where the accident occurred and could have been endangered by the runaway truck.This citation was terminated October 27, 1999. The mine operator has reinforced its policies and requirements for compliance with each drill rig contractor and has conducted a verification audit with each drill rig contractor.
Related Fatal Alert Bulletin: 
FAB99M34
APPENDIX A
Persons Participating in the Investigation
Rio Algom Mining Corporation
William P. Goranson, manager radiation safety, regulatory compliance & licensingPronghorn Drilling Company
Terry W. Warner, supervisor, administration & personnel
Kenneth L. Holman, safety engineer
Robert E. Taylor, ownerKid Pronghorn Ent.
James L. Sandstedt, driller
Jeffery S. Wilcox, drill helperState of Wyoming
Donald G. Stauffenberg, state inspector of minesMine Safety and Health Administration
Donald G. Hendricks, deputy inspector of mines
Tyrone Goodspeed, supervisory mine safety and health inspectorAPPENDIX B
Joseph O. Steichen, mine safety and health inspector
Dennis Ferlich, mechanical engineer
Jeffrey J. Ream, civil engineer
Persons Interviewed
Pronghorn Drilling Company
Robert E. Taylor, ownerKid Pronghorn Ent.
James L. Sandstedt, driller
Kurt E. Taylor, owner
Jeffery S. Wilcox, drill helper