Abstract: Employees were installing a new pump in building #73 of a chemical plant that extracts tantalum and niobium from raw ore. A chemical plant operator placed a dumpster containing waste product and residual hydrofluoric acid in the area where Employees #1, #2, and #3, contractors, were working. The plant operator was not aware that the employees were in the area. When Employees #1 through #3 smelled the acid, they knew it was hazardous from the training they had received and were cautious. The operators in the building told the employees to go to the dispensary and have someone call an ambulance. When the ambulance arrived, Employees #1, #2, and #3 were given calcium glutonate intravenously to prevent injury from the hydrogen fluoride. The employees were admitted to the hospital for overnight observation because they lived a significant distance away from the hospital. Employees #1, #2, and #3 did incur some lung burns. The site emergency response team responded to the area of the exposure and determined with a detector tube that the air contamination level was approximately 3.5 ppm.