Abstract: Employee #1 climbed atop an 8 ft diameter underground storage tank to spray petroleum dispersant inside the tank. Employee #2 began cutting an inspection hole in one end of the tank. No tests were performed within 10 minutes. Employee #2 made a 2 ft long horizontal cut, then had begun to make a 2 ft long vertical cut when a fire started and the tank exploded. The tank end blew out and away from where Employees #1 and #2 were located. Employee #1 fell to the paved parking lot, and suffered a broken knee cap. Employee #2 was slightly burned by the hot liquid sprayed from the tank. Employees #3 and #4, who were watching the process, were slightly injured. Employee #3 was struck in the face by debris and sustained minor cuts. Employee #4 fell to the ground and sustained a minor cut to his knee.