Abstract: At approximately 8:00 p.m. on October 21, 2005, maintenance employees were emptying the Herman Return Sand Silo. Because there was build up on the sides of the silo, a floor opening in the Herman Return Sand Silo Tower was uncovered to view the areas of build up and to stick an air wand inside the silo to help blow the sand loose. The silo was emptied at approximately 5:00 a.m. on October 22, 2005. At approximately 7:00 p.m. on October 22, 2005, maintenance employees were preparing to enter the silo when they saw Employee #1 inside the silo. Employee #1 had gone into the Herman Return Sand Silo Tower to do some vacuuming, did not see the floor opening to the silo and fell into it. The opening was approximately 21-in.-square and Employee #1 fell approximately 20 ft, possibly striking some surfaces inside the silo on the way down. Employee #1 was killed.