Abstract: Employee #1 was an eight-year veteran truck driver for an excavating contractor that buys and hauls base rock material from Sonoma Rock, a quarry/crushing plant. He had just been loaded at the plant with 3/4 in. AB crushed rock material and was returning to the stockpile loading area to dump 3,000 lb of excess material. He jackknifed his Fruehauf trailer drawbar (PT10), backed up his Kenworth truck (P10) to within 10 ft of the toe of the stockpile high wall, and raised his truck box approximately 45 degrees. He got out of his truck and proceeded to the rear of the truck, where he began unloading the excess material through the 14 in. by 16 in. chute opening of the tailgate. While he was shoveling material, the unstable part of the approximately 30 ft high wall collapsed and buried him for half an hour under 7 to 8 cubic yards of base rock material. The probable cause of death as given by the coroner was asphyxiation from compression of his thoracic muscle.