Abstract: At approximately 1:30 p.m. on October 20, 2008, Employee #1, a water treatment operator trainee, was exposed to fluorosilicic acid (FSA) during a spilled acid containment process. On the day of the accident, Employee #1's coworker, a water treatment operator, while attempting to correct a small leak, discovered an acid transfer from a rail car to a bulk storage container. He cut off the zip tie and disengaged cam locks without depressurizing the system, which was under pressure of 30-35 psi. The action led to uncontrolled acid discharge, where 2,700 gallons of FSA was geysered out of the rail car carrying 90 tons of FSA. Employee #1 responded to the spill and was performing containment work without a respiratory protection, such as self contained breathing apparatus. Employee #1 was exposed to FSA vapors and mists and was transported to the Providence Holy Cross Medical Center. He was hospitalized for four days. The investigation concluded that the injury was a result of Employee #1's entry into an area, where the concentration of the contaminant was unknown, and lack of protection from inhalation hazards.