Fatality Assessment and Control Evaluation (FACE) Report for Maryland: Two Utility Workers, Were Working in a Trench Next to a Road, When a Valve Blew Off a 10 Inch Water Main and Rapidly Filled and Excavation Before They Could Be Rescued.

摘要

On Tuesday, July 22, 1997, at approximately 10:30 a.m., a valve that they had replaced, blew off a 10 inch diameter water main. Water, under pressure of about 100 p.s.i., quickly filled a trench approximately 4 foot 6 inch deep by 6 foot long and 6 foot wide. The valve struck a 43-year-old, male, Utility Worker no. 1 (victim 1), injuring him severely and caused him to be lost in the swirling water. As the 28-year-old, male, Crew Chief (victim 2) was attempting to rescue Utility Worker no. 1, the ground on which he was standing was undermined by the water and collapsed. He fell into the excavation and was pulled under the muddy water. The utility company Backhoe Operator, who was trying to help those in the excavation, stopped an ambulance returning to its station. Ambulance personnel immediately called for assistance and within fifteen minutes several rescue units were at the scene. The Backhoe Operator also called in an emergency to the company dispatcher. He and Utility Worker no. 2 went on to shut the valves and stop the rapid flow of water from the 10 inch main into the excavation. The body of the Crew Chief (victim no. 2), was recovered after the water was pumped out of the excavation (20 - 30 minutes) by the fire department and the utility company. Utility Worker no. 1 (victim no. 1) was removed approximately four hours later, since his body was buried in the mud and had become entangled in ground roots and a gas line. Both were pronounced dead at the scene. The MD/FACE Field Investigator concluded that to prevent similar future occurrences, employers should: (1) Ensure that all employees working on high pressure water mains understand and recognize the hazards associated with hazardous hydraulic energy and the methods of avoidance; (2) Require that water mains be isolated and de-energized before working on the system; and (3) Require the use of a trench box, shoring or properly sloped sides when working in an excavation.