Fatal Accident Circumstances and Epidemiology (FACE) Report: Digester Explosion Kills Two Workers at Wastewater Treatment Plant in Pennsylvania, February 6, 1987

摘要

During drainage of a sewage digester taken out of service for routine cleaning, an explosion lifted the 30 ton floating cover, killing two workers at a wastewater treatment facility on February 6, 1987. Experiencing difficulty in removing the sludge from the bottom of the 30 feet deep digester, the two victims climbed on to the floating cover of the digester to pump water into it, in an effort to loosen the sludge. The driver of the pumper truck reversed his pump to blow air up through the sludge to aid in loosening it. The victims lowered a light bulb (the light and cord were not approved for hazardous operations) into the digester to view the sludge level. The bulb apparently broke, providing a source of ignition for the combustible gases in the digester, likely methane (74828). The floating cover was found to be wedged into the digester at a 45 degree angle. The victims were removed about 4 hours later from the digester. Cervical fracture was listed as the cause of death for both men. It was recommended that proper work procedures be developed and employees trained in these procedures and that comprehensive policies and procedures be developed for confined space entry.