Abstract: At approximately 8:30 p.m. on August 29, 1991, Employee #1 was changing pipes from one tank to another in an ammonia tank farm area. As he walked from tank A-5 to tank A-2, he tripped on a drainage trench, lost his balance, and fell against the line, breaking the valve of tank A-2. The drainage trench is about 20 ft long by 2 in. wide by 1 1/2 in. deep. Ammonia etchant solution contained in the tank was released and entered his boot, burning his lower right leg. Employee #1 immediately called the fire department and temporarily controlled any further release by plugging the valve. Employee #1 did not know he was burnt until he was taking a shower and felt pain on his lower right leg when he scrubbed it with soap. Employee #1 was taken to Health First Medical Group at about midnight and was released at about 1:30 a.m. Employee #1 had received training on hazard communication and contingency plans. There was no accident related violation found after the investigation.