Abstract: On May 30, 1986, Employee #1 was hosing down the inside walls of a 10,000 gallon, horizontally-mounted, steel storage tank while standing on a ladder inside the 28 in. open-top hatchway. No effective ppe was in use. The tank was full of decomposed hog entrails and a mixture of hydrogen sulfide and carbon monoxide had formed above it. Employee #1 passed out and fell into the tank. Employee #2 saw what had happened and, taking no precautions, entered the tank to rescue Employee #1. He, too, fainted and fell into the tank. Both employees died of asphyxia. A coworker summoned a foreman who was in the locker room taking a shower. The foreman put on pants and shoes, ran to the tank, and climbed partway up the attached outside ladder. He thought he could help rescue Employees #1 and #2 but, when he realized what had happened, he contacted 911. The Des Moines Fire Department rescue unit recovered the bodies of the two employees. No effective ppe was in use at the time of the accident.