A worker was killed in an 8-foot-deep trench when a water line broke and filled the trench with water and dirt, which turned into a thick mud.
The worker, an untrained day laborer, became submerged under the mud and couldn’t be rescued by his co-workers.
Investigators with the California State Fatality Assessment & Control Evaluation (FACE) Program determined that failure to have a competent person onsite and a lack of safety training contributed to the fatal incident.
Unlicensed plumber hires 4 day laborers to dig trench
On Sept. 14, 2022, the owner of a mobile home park called the plumber he had on retainer to fix a problem with the park’s sewer line.
The plumber was self-employed, had no employees and lacked a state-issued plumbing contractor’s license. After getting the request, the plumber hired four day laborers from a local home supply store to dig a trench and expose the faulty sewer line. The day laborers all spoke Spanish. The plumber’s primary language was English, but he could speak some Spanish.
While the plumber had worked for the mobile home park for several years, he didn’t have a written safety program or an injury and illness prevention program as required by California law. He provided no safety training related to trenching to the four day laborers.
The day laborers were instructed to dig the trench in a walkthrough between mobile home residences so the plumber could get to the faulty sewer line. There was also a water line running through the same area about 3 feet below the surface. Because of the restricted space, they had to use shovels to dig the trench.
They dug a trench that was about 4 feet wide, 30 feet long, 8 feet deep and had no shoring.
Water line breaks, fills trench with dirt and mud
While digging, they exposed the 3-inch water line. There was no attempt made to shut the water line off before continuing their work on the trench. Once two of the day laborers reached a depth of about 8 feet, the exposed water line broke and began filling the trench with water and dirt that was knocked loose by the pressurized water.
The two day laborers on the surface tried to rescue their co-workers but the thick mud was already up to the chests of the trapped workers. It took almost 10 minutes for the workers on the surface to pull one of the day laborers out of the mud-filled trench. The other day laborer in the trench became submerged and his co-workers were unable to locate him.
An unsecured ladder was in the trench, but the co-workers weren’t able to use it in their attempts to free the trapped day laborers.
Multiple fire and rescue departments eventually arrived on the scene and removed the water and mud from the trench. The trapped day laborer was extracted from the trench after eight hours and was pronounced dead on the scene from traumatic asphyxiation.
No shoring or competent person onsite contributed to incident
Investigators learned that the plumber failed to get required permits to dig the trench and was onsite when the incident occurred but not in the area of the trench. How the plumber knew the depth or location of the sewer line, the soil composition and the presence of other utilities is unknown.
The FACE investigation revealed that factors contributing to the incident were:
- the lack of a competent person onsite
- failure to get permits to perform the work
- a lack of shoring
- failure to turn off the water line before digging, and
- a lack of safety training for the day laborers.
To prevent similar incidents, FACE investigators made several recommendation, including:
1. Shoring, shielding or sloping trenches when required
When a trench is 5 feet deep or deeper, OSHA requires that employees are protected from cave-ins by an adequate protective system. Trenches at risk of cave-in must be sloped, benched, shored or shielded.
The type of protective, support or shield system that should be used is dependent on the soil conditions found in the excavation.
In this incident, the protective system should have included a trench box, shoring, or a combination of shoring and shielding, according to the FACE report. Sloping wouldn’t have been appropriate because of the limited space in play.
2. Ensuring trenches are inspected by a competent person
A competent person is defined by OSHA as “one who is capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate them.”
That means the competent person must have:
- knowledge of all safety requirements pertaining to excavations, trenches, and earth work
- knowledge of the soil analysis of the work site
- knowledge in the requirements for and use of protective systems, and
- the authority to take prompt corrective action on the job as conditions warrant.
In this incident, the plumber wasn’t a competent person as defined by OSHA. If a competent person had been onsite and making inspections, then the workers wouldn’t have been allowed to enter the unprotected trench.
3. Making sure workers receive proper safety training
Employers need to make sure that workers, whether they’re full time employees or not, are properly trained regarding trenching hazards.
In this incident, the workers were day laborers hired by the plumber. They were never properly trained on the hazards they would face when working in a trench.
Day laborers are workers who meet at well-known locations, usually public street corners or commercial parking lots, and wait for building contractors, landscapers, homeowners, and other potential employers to offer work, the FACE report said.
No matter if the worker is a day laborer, a temporary employee or a full-time employee, they need to have the same level of safety training to prepare them for the possible hazards they may face. If the worker’s primary language isn’t English, then their training must be done in a language they can understand.