Tri County Materials found liable in Morenci mine death


Contributor Photo: This aerial view shows the Tri County Materials cement truck on its side after hitting a berm when its brakes failed.

By Jon Johnson

SAFFORD — The Mine Safety and Health Administration’s final fatality report into the Jan. 28 death of Monroe Caston Jr., 56, in a concrete mixer accident at the Morenci Operations mine site in Freeport McMoRan listed the employer of Caston, Tri County Materials, a ready-mixed concrete supplier to Safford, responsible for the accident.

At the time of the accident, the cement truck was loaded and descending a ramp when the service brakes failed. The truck accelerated rapidly and passed its escort vehicle before losing control on a curve, overturning and sliding into a berm.

Another employee, David Butler, was a passenger in the Mack CV513 cement mixer truck and was seriously injured. None of the occupants was wearing their seat belts at the time of the accident.

According to the report, Tri County Materials “engaged in conduct amounting to more than ordinary negligence in that the brake failures were reported to the mine operator on January 20, 2022 and no effort was made. was done to correct the dangerous condition. This breach is an unwarranted failure to meet a mandatory standard. The report lists three orders and three citations for Tri County Materials and states that the company also did not “remove the defective equipment from service” and that “no effort was made to ensure that consistent and adequate pre-operational inspections were conducted to correct the conditions.”

Contributor photo: The investigation revealed that the truck’s brakes were defective.

Investigation revealed that three of the cement truck’s four brakes were out of adjustment beyond out-of-service criteria, one rear drive axle had mismatched brake chambers, driver’s side brake shoes were not positioned correctly , one of the brake actuators was leaking, and five of the six brake components were worn beyond retirement criteria.

In summary, the report concluded that Tri County failed to keep brake systems in working order, failed to conduct adequate pre-operational reviews, and failed to ensure that all miners were wearing seat belts.

“The accident occurred because the contractor that employed Caston and Butler, Tri County Materials Inc (Tri County), failed to: 1) maintain the brake systems in working order and remove service equipment until defects that make continued operation unsafe have been corrected, 2) perform adequate pre-operational examinations on mobile equipment prior to operation, and 3) ensure that minors were wearing seat belts,” the report said.

After the incident, Tri County took all of its trucks out of service and inspected brake systems before putting them back in place and developed written criteria for removing faulty equipment from service, a written SOP for reviews pre-operational mobile equipment and regarding the seat belt. use when all vehicles are in motion.

Timeline of the incident

“On January 28, 2022, Caston and Butler arrived at Tri County Equipment Park in Safford, Arizona at 4:30 a.m. to start their shift. Caston completed a pre-operational examination file for the mixer truck company number M14. Caston drove this mixer truck to the Freeport-McMoRan Morenci Inc. mine in Morenci, Arizona, with Butler, his passenger, who was training as a mixer truck driver.

At 6:03 a.m., Caston and Butler arrived at the mine gate and proceeded to the concrete plant to await their first load. At 7:21 a.m., Caston and Butler received their first load of ten cubic yards of concrete. At 8:23 a.m., Caston and Butler hauled concrete from the batching plant to the Shannon Booster Project site. At 8:35 a.m., the concrete load was rejected by PVB Fabrications Inc because it was too wet. After washing the chute of the cement mixer truck, Caston and Butler drove the loaded vehicle up the northwest ramp to the batch plant to dump the load of rejected cement. Caston and Butler were following an escort vehicle through the mine, which was driven by a Mixer Driver.

According to Butler, as Caston and Butler descended the northwest ramp, they lost use of the service brakes on the cement mixer truck and the speed of the truck rapidly increased. At 9:03 a.m., Caston and Butler passed their escort vehicle and a Caterpillar 793D haul truck driven by a haul truck driver, which was also coming down the northwest ramp. Owen radioed that the cement truck had passed her and said the cement truck was going faster than the speed limit on the haul road. As the mixer truck continued down the northwest ramp, it continued to accelerate, lost control on a curve, rolled onto its side, and slid into a berm.

At 9:09 a.m., the first person on the scene, a tank truck driver, called a “Mayday” on the radio to alert mine personnel that a serious accident had occurred. According to the tank truck driver’s interview, the two miners were ejected from the truck. At 9:12 a.m., a transport truck driver, also trained as an emergency medical technician (EMT), arrived on the scene and began administering first aid. Shortly after, another trained paramedic arrived on the scene. Paramedics extracted Caston from the cabin and moved him to a safe location to assess his injuries and begin treatment. At 9:23 a.m., the FMI ambulance team arrived on the scene and took care of Caston. Then a second Greenlee County ambulance arrived and took care of Butler. Caston and Butler were transported by two ground ambulances to the Gila Health Resources Clinic. Butler was transported overland and Caston was airlifted to Banner University Medical Center in Tucson, Arizona, where Caston was pronounced dead at 6:58 p.m.

The most recent fatal accident at the Morenci mine occurred on September 15, 2021, when Cleveland Sloan, a 33-year-old contract welder with more than 10 years of mining experience, slipped into confined space inside a stainless steel pipe. was welding and died of asphyxiation from the argon gas used in the welding process. Sloan was employed by PVB Fabrications, a contract manufacturing service. The MSHA released a final report on the death in May.

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