UNITED STATES
DEPARTMENT OF LABOR

Abstract: On April 1, 2009, Employee #1, a machine operator, was directing the placement of equipment mats along a wetland area. Each mat weighs between 2,500 lbs to 3,500 lbs and is constructed from timbers measuring approximately 18 feet long by 4 feet wide. Additionally, each mat contains four to six timbers, which are secured together by the use of a one inch bolt/rod. The bolts/rods are placed at four locations, spaced along the length of the mat. An exposed section of the bolt/rod is left at the end of the mats to assist with their placement through the use of a hook. The mats were to be used to support a John Henry drill machine, which Employee #1 was intended to use to drill holes for explosive charges in rocky areas. While Employee #1 was directing the placement of the mats, a Caterpillar excavator, Model Number 330D, was being used to transport and place the mats. The excavator was also equipped with a standard bucket, Type 269-2693, with a four tip constructed bite width of 42 inches, and a weight capacity of 1.54 cubic yards. On the backside of the bucket, an eyelet, with a load rating of approximately 20 tons, existed where a 10-inch Crosby shackle (rated at 17 tons) was fastened. Then attached to the 10-inch shackle was an 8.5 inch Crosby shackle, rated at 12 tons. Finally, a swivel hook with a working load of 11 tons, Model Number S-3322, is then attached to the 8.5 inch shackle. Five out of six mats were successfully put into place; however, as the fifth mat, the sixth mat required to be lifted up and over a slit fence that was located near a ditch. As the excavator operator transported the last mat, the equipment bounced, causing the mat to come into contact with the ground. The mat disengaged from the hook and struck Employee #1, killing him. The accident investigation revealed that other workers, in addition to Employee #1, were exposed to the suspended load created during the transporting and placing of the mats while attaching and detaching the hooks.