MINE SAFETY AND HEALTH ADMINISTRATION
North Central District
Metal and Nonmetal Mine Safety and Health
Accident Investigation Report
Surface Nonmetal Mine
(Sand and Gravel)
Fatal Machinery Accident
Hahn Ready Mix Company
Hahn Ready Mix Company Mine
Muscatine, Muscatine County, Iowa
I.D. No. 13-00683
July 14, 1998
Ralph D. Christensen
Supervisory Mine Safety and Health Inspector
Thomas J. Pavlat
Mine Safety and Health Specialist
Mine Safety and Health Administration
Federal Building, U.S. Courthouse
515 W. First Street, #333
Duluth, MN 55802-1302
Felix A. Quintana
Dean Tiecke, dredge operator, age 63, was fatally injured at about 2:30 p.m. on July 14, 1998, when he became entangled in the drive unit for a jaw crusher. Tiecke had a total of seven years mining experience, all as a dredge operator with this employer. He had received training in accordance with 30 CFR, Part 48.
MSHA was notified at 5:10 p.m. on the day of the accident by a telephone call from the safety director for the mining company. An investigation was started the following day.
The Hahn Ready Mix Company mine, a sand and gravel dredging operation, owned and operated by Hahn Ready Mix Company, was located at 2470 Industrial Connector in Muscatine, Muscatine County, Iowa. The principle operating officials were Thomas R. Hahn, president, and Brian T. Hahn, vice president of operations. The mine was normally operated one, 8-10 hour shift a day, five days a week. A total of three persons was employed.
Sand and gravel was extracted from a pond by a dredge, referred to as the rock dredge. Material was pumped from the rock dredge to the rock boat where the sand was screened off and pumped to a settling pond. The rock was crushed and conveyed to shore. Finished products were sold for use as concrete aggregate and landscape rock.
The last regular inspection of this operation was conducted on October 22, 1997. Another inspection was conducted following this investigation.
The equipment involved in the accident was a Deco H2624A, 10- x 16-inch jaw crusher located on the deck of the rock boat. It was driven by a 480-volt electric motor which was connected to its drive sheave by eight V-belts. The pinch point created by the V-belts at the sheave was about 52 inches above the crusher deck. A 30-inch wide walkway with an outboard railing was provided adjacent to the drive. The guard for the drive had been removed two weeks prior when new belts were installed and was laying on the walkway against the railing. Clearance between the drive sheave and the guard laying on the walkway was 8 inches.
The dredge had been picking up wood debris from the pond due to recent storms, which was clogging the crusher discharge chute. Employees would stand on the crusher framework to pick out debris during operation. Weather on the day of the accident was hot and humid.
On the day of the accident, Dean Tiecke (victim) reported for work at 7:00 a.m., his regular starting time. He operated the rock dredge until about 10:30 a.m., when Charles Richardson, another dredge operator, arrived. Tiecke was removing debris from the transfer chute between the screen and the crusher on the rock boat. A short time later, he returned to the dredge while Richardson remained on the rock boat to watch for hangups.
Dredging continued until about 12:30 p.m., when a flange gasket on the sand pipeline sprung a leak. After repairing the leak, Richardson and Tiecke used the work boat to remove wood debris from the water. Shortly thereafter, Tiecke left to monitor the flow of material on the rock boat.
After about an hour of dredging, Richardson noticed that material had stopped flowing from the stacking conveyor on the rock boat and saw what appeared to be a red hat on the walkway. He ran to the rock boat to look for Tiecke. It was evident that Tiecke had been entangled in the crusher drive belts, but Richardson could not find him. Richardson ran back to the rock dredge and called Dan Werner, plant manager.
Werner went to the rock boat, followed by Thomas Hahn, Brian Hahn, and several others. After searching the area, the local police and fire departments were summoned. The victim was located about 30 minutes later in the water, partially under the pontoon on the northeast side of the rock boat.
Tiecke was pronounced dead at the scene a short time later. The cause of death was attributed to severe trauma injuries to the chest and extremities.
The direct cause of the accident was failure to maintain the guard in place while the crusher was in operation. A major contributing factor was management's failure to ensure that daily workplace examinations were conducted and safety hazards promptly corrected. The practice of cleaning debris from the discharge chute while the crusher was operating was also a contributing factor.
Order No. 4538213 was issued on July 15, 1998, under provisions of Section 103(k) of the Mine Act:
A fatal accident occurred at this mine when a dredge operator contacted the pinch point area of the drive belts and sheaves of a crusher. This order prohibits any further work activity until the affected area can be returned to normal operation as determined by an authorized representative of the Secretary.
This order was terminated on July 17, 1998, after it was determined that the mine could safely resume normal operation.
Citation No. 7816181 was issued on August 18, 1998, under provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 56.14112(b):
A dredge operator was fatally injured at this mine on July 14, 1998, when he became entangled in the unguarded drive unit on the jaw crusher. The guard for these moving machine parts had been removed and left off for more than two weeks prior to the accident. Failure to assure that this guard was in place constitutes more than ordinary negligence and is an unwarrantable failure to comply with a mandatory safety standard.
This citation was terminated on August 18, 1998. The mine operator has determined that the crusher is not needed and has permanently removed it from service.
Order No. 7816182 was issued on August 18, 1998, under provisions of Section 104(d)(1) of the Mine Act for violation of 30 CFR 56.18002(a):
A dredge operator was fatally injured at this mine on July 14, 1998, when he became entangled in the unguarded drive unit of the jaw crusher. The guard for this drive unit had been removed and left off for more than two weeks prior to the accident. This safety hazard was readily visible to anyone entering the area, yet the mine operator maintained documentation which showed this area had been examined daily for conditions which may adversely affect safety. A properly conducted examination and promptly initiated corrective action could have prevented this accident. Failure to properly conduct examinations and to initiate corrective action is a 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 on August 20, 1998. The mine operator has revised the working place examination procedures. The maintenance manager has been designated to conduct an examination of all work areas prior to the start of each shift. The procedures require that all hazards found will be corrected before the start of the shift, or promptly when they are found during the shift.
Citation No. 7816183 was issued on August 18, 1998, under the provisions of Section 104(a) of the Mine Act for violation of 30 CFR 56.14105:
A dredge operator was fatally injured at this mine on July 14, 1998, when he became caught in an unguarded crusher drive near the throat area of the jaw crusher as he prepared to clear debris. The crusher was operating at the time.
This citation was terminated on August 31, 1998. The mine operator developed a comprehensive procedure which must be followed before any work is done on equipment which must be locked out and blocked against motion. All employees have been trained on the new procedure.
Related Fatal Alert Bulletin: