Abstract: On April 27, 2009, Employee #1 was working at a truck maintenance facility. The facility had installed an above ground atmospheric storage tanks for used motor oil piped out from the maintenance bay. The tanks were in a concrete confinement area placed below surface level. During the initial use of the tanks, employees noticed a leak coming from the first 500 gallon tank in the chain. Employee #1 clamped the drain valve and emplaced a catch pan under the valve of the first tank. A coworker attempted to empty the tank by the use of compressed air. The tank was closed without venting. The tank end where the Employee #1 worked burst, striking him on the head and pinning his head against a concrete wall. He died from blunt force trauma.