Powered tools are amazing things. While they are invaluable on the job, many can be lethal if misused. That is certainly true of a cleaning nozzle attached to a high-pressure hose on a combination cleaning truck.

An incident in Iowa illustrates the point. Although this happened several years ago, the lessons it teaches are timeless. A 29-year-old public works employee died when he was struck by a nozzle on a high-pressure water hose he was using to clean a sewer. The accident happened because the employee, although experienced, failed to follow proper procedures at the end of a jetting run in a sewer main.

 

Well trained

According to a report from the National Institute for Occupational Safety and Health, Fatality Assessment and Control Evaluation (FACE), two city employees were doing routine cleaning of the sewer line using a combination truck. At the end of the routine, the nozzle came back up through the manhole with the hose under pressure and struck the truck operator in the head. He died at a hospital two days later.

FACE personnel investigated the incident through a site visit, discussions with the city administrator, review of police and medical examiner reports, and the OSHA inspection file on the case.

The city had 65 full-time employees, 21 in the public works division. The victim had worked for the city for about one year as an equipment operator and laborer, had been trained to operate the combination truck, and had completed more than 200 sewer cleaning jobs.

The city had an extensive safety program, written safety policies and procedures, and a good safety record. New employees received training upon joining crews and every year from then on. Employees using the combination truck were trained for several weeks, during which time they worked under an experienced supervisor.

 

Out of sight

A cleaning crew generally included two employees, one operating the truck and the other at the manhole upstream. On the day of the incident, the victim was with a co-worker who was at the next manhole about 500 feet away, not visible because a ravine and landscape stood between the two positions.

The men were using a 1-inch-diameter steel nozzle. Pressure at the nozzle was estimated at 1,100 to 1,200 psi, and the flow at 80 gpm. The victim had set up the hose and the standard “tiger tail’ in the manhole, which was 24 feet deep, to clean the 8-inch line. The water pressure from the truck propelled the nozzle down the line until the co-worker heard it approach the upstream manhole, at which point he radioed his colleague.

The victim then started reeling the cleaning nozzle back to the truck. Eventually the co-worker heard the truck idle down and knew the cleaning nozzle was back at the start of the line. He could tell that the victim had turned the water off, since the normal sound of waterjetting had stopped.

Soon after, the victim radioed that the hose had been removed from the line. The co-worker began to replace the manhole lid when he heard the truck idle back up to operating speed. Then he heard boys screaming and knew something had happened.

He hurried back to the truck to find the victim lying near the manhole with massive head injuries. The co-worker saw that the pump motor and truck engine were still running, so he immediately shut them off, pump motor first.

The victim had been wearing a hardhat, which was found on the pavement about 20 feet away. Emergency responders arrived, treated the man, and took him to the local hospital. Bystanders reported that they heard something like an explosion from the back of the truck, like the sound of a loud bottle rocket. They saw the hose spraying water into the air and the victim lying on the street, and immediately called 911.

 

Fatal mistake

When cleaning is complete in a section of line, the FACE team observed, the proper procedure is to bring the tiger tail and nozzle up at the same time, remove the tiger tail, attach it in position on the truck, and then wind the hose back onto the reel.

For no apparent reason, the victim removed the hose from the tiger tail assembly, but then put the hose back into the manhole and turned on the water pressure, possibly to clean out some debris. With the hose under operating pressure and unrestrained, the nozzle came back up through the manhole and hit the employee in the head, knocking him backward. The hose then shot straight up into the air with water spraying out.

The manufacturer of the truck took the unit out of service for a number of days to review the matter. The pump had 195 operating hours and the truck itself 550. The investigation showed the equipment to be in good working condition with only normal wear to some components. The truck was put back into service after the review.

 

Safety reminder

The FACE team made two recommendations: Employees should always follow manufacturers’ instructions when operating equipment, and safe work practices should be re-emphasized during staff meetings. That includes reminders about the consequences of misusing equipment that operates under high pressure.

The NIOSH FACE program gives safety officials access to the full text of hundreds of fatality reports by way of a website at www.cdc.gov/niosh/face. These reports, whether or not related directly to sewer cleaning, can help provide insights to the cause of accidents, and therefore to prevention.