Abstract: At 8:15 a.m. on July 17, 2012, Employee #1 and Employee #2 were in the process of flushing and cleaning a power plant fly ash silo with water, a task they had performed numerous times before at the mill without injury. Both employees were standing on a Genie Z-60/34 aerial lift in an elevated position outside of a building housing ash silos for the power plant. The doors at the top of the east silo were open and the employees were using a 1 1/2" high pressure hose to knock the buildup of ash off of the inside of the silo. This material would then have flowed out the bottom of the silo into the mixer and into a hopper. While performing this task, Employee #1 and Employee #2 were engulfed by a cloud of steam and hot ash that came out of the silo they were cleaning. The employees lowered themselves to the ground and sprayed cold water onto themselves until help arrived. The investigation determined that at the time of the accident the employees were not using personal protective equipment. The incident may have been caused by an obstruction of the opening at the bottom of the silo which would have prevented the water from the hose to drain. This would have caused the excess water to accumulate and heat up, which in turn would have produced a cloud of steam, water and ash. Employee #1 and Employee #2 were both engulfed and killed from the cloud of steam, water, and ash.