Ashtabula, OH. At approximately 11:30 a.m. on April 25, 2007, two employees arrived on the site to replace a leaking oil and brine tank. This tank was a 210-tank, called this because it holds 210 barrels, which is approximately 8,800 gallons. Although these tanks are made of 0.125-in. thick steel on the sides and 0.25-in. thick on the bottom they tend to rust out and leak at the bottom because water collects near the tank on the ground. It was raining on the day of the incident. The two employees went back into the woods about 500 ft from the road to shut down the well valve. They then went back to the tank and closed the valve at the gas-oil separator. The separator serves to send gas to a pipe line and send the oil to the brine tank. They next uncapped the drain valve, connected the vacuum truck to the fitting and opened the valve so that the vacuum truck could pump out the tank. This removed all but 3 in. of the brine and oil mixture from the tank. Employee #1 next climbed up the tank on a ladder and stood on the tank top and began to disconnect pipes at the hammer union. The coworker needed to remove the final 3 in. of fluid from the tank. The coworker planned to grind a notch in the tank with an electric grinder powered by a truck mounted, portable gasoline powered welder and generator. After grinding the notch the coworker planned to use a reciprocating hand held saw to cut a hole so that he could drop a hose into the tank and pump out the remaining liquid. The coworker cut a shallow notch in the tank and realized that the notch was not deep enough. The coworker was getting ready to grind the notch deeper but the plug of the grinder cord came out of the extension cord. When the coworker tried to plug the grinder back in he got a shock and dropped both the grinder and the cord and walked away. Thirty seconds to sixty seconds later there was a whooshing sound and Employee #1 saw a big ball of fire and was thrown into the air. Employee #1 landed approximately 75 ft away and suffered a severe leg fracture. Employee #1 was hospitalized.
OSHA Accident Report: http://www.osha.gov/pls/imis/establishment.inspection_detail?id=311078562