Abstract: At approximately 5:40 a.m. on April 7, 2011, a 52-year-old plant operator working for A. Teichert & Son Inc. reported to work. Employee #1 conducted his normal preoperational check of the Teichert Woodland aggregate plant. Employee #1's assigned duties were to inspect any parts, tools, or other material that may have been left on any of the conveyor belts by the previous night maintenance crew. The rest of the crew showed up shortly thereafter. The plant started, and the mined material began to make its way through the process. Employee #2, a laborer, noticed a hole in a material chute in the No. 196 tunnel conveyor system. Employee #1 was joined by Employee #2 in the reclaim tunnel to schedule and plan a repair operation. As the two Employees exited the tunnel and walked away from the overhead No. 196 Conveyor, a 10 pound rock fell off the conveyor striking Employee #1 in the head and Employee #2 in the back, knocking both employees to the ground. Employee #1 was knocked unconscious and landed on top of Employee #2. Employee #2 was able to drag Employee#1 away from the No. 196 Conveyor and call for help. The Fire Department arrived, and Employee #1 was transported to a medical center with a head injury.