Abstract: Employee #1 and two coworkers were drilling a series of water wells for the US Borax Company at a mine site in Boron, California. The wells were to be used to remove water from the quarry area. The crew had dug a 18 ft by 12 ft 8 ft deep receiving pit, the bottom of which was filled with approximately 3 ft of water. A foam detergent used in the drilling process filled the pit and the surrounding area, hiding its boundaries. On the last hour of his shift, Employee #1 entered the cab of the truck to start the engine. While exiting the truck, he stepped into the foam filled pit and went under; he was not missed for approximately 30 minutes. Coworkers found Employee #1 at the bottom of the pit; he had drowned.