REPORT#: 22CA003 REPORT DATE: November 1, 2023

Day Laborer Dies in a Collapsed Trench Being 

Dug to Repair a Sewer Line — California

______________________

SUMMARY

On September 14, 2022, a 34-year-old Hispanic day laborer, along 

with three other day laborers, dug an eight-foot-deep trench to 

expose a damaged sewer line. Unexpectedly, while digging, they

exposed and broke a water line. Water and dirt filled the trench and 

created a thick mud. The victim became submerged under the mud 

and was unable to be extracted by co-workers or rescue personnel.

READ THE FULL REPORT> (p.3)

CONTRIBUTING FACTORS

• Lack of competent person onsite.

• Permits were not requested or issued for the work being

performed.

• Workers were in an eight-foot-deep trench with no shoring.

• Water line was not turned off before or during work.

• Lack of training for workers in trenching safety.

LEARN MORE> (p.6)

RECOMMENDATIONS

California FACE (CA/FACE) investigators concluded that, to help 

prevent similar incidents, mobile home park owners and plumbing 

contractors should ensure:

• Trenches five feet deep or greater are properly shored, shielded, or

sloped.

• Trenches are inspected by a competent person.

• A licensed plumbing contractor is used to perform trenching and

excavation work.

• Day laborers are properly trained on hazards associated with

working in a trench.

LEARN MORE> (p.6)

INCIDENT HIGHLIGHTS

DATE: 

September 14, 2022

TIME:

11:30 a.m. 

VICTIM:

34-year-old day laborer

INDUSTRY/NAICS CODE: 

Plumbing / 238220

EMPLOYER: 

Plumber

SAFETY & TRAINING:

None

SCENE: 

Walkthrough within a 

mobile home park

LOCATION:

California

EVENT TYPE:

Asphyxiation
Fatality Assessment and Control Evaluation (FACE) Program

This case report was developed to draw the attention of employers and employees to a serious safety hazard 

and is based on preliminary data only. This publication does not represent final determinations regarding the 

nature of the incident, cause of the injury, or fault of employer, employee, or any party involved. 

This Case report was developed by the California Fatality Assessment and Control Evaluation (FACE) Program. 

California FACE is a NIOSH-funded occupational fatality surveillance program with the goal of preventing fatal 

work injuries by studying the worker, the work environment, and the role of management, engineering, and 

behavioral changes in preventing future injuries. The FACE program is located in the Occupational Health 

Branch, California Department of Public Health. 

Email | Website

Page 2 
INTRODUCTION 

On Wednesday, September 14, 2022, at approximately 11:30 a.m., a 33-year-old Hispanic day laborer

(the victim) was asphyxiated inside an eight-foot-deep trench that was being dug to repair a sewer line in 

a mobile home park. The CA/FACE investigator received notification of this incident on September 19, 

2022, from the weekly occupational fatality summary from the California Department of Industrial 

Relations Public Information Office. Contact with the employer (a plumber) was made by the CA/FACE 

investigator on October 26, 2022. The CA/FACE investigator interviewed the plumber and the owner of 

the mobile home park about the incident. The police and fire department reports (including co-worker 

statements) were received and reviewed.

EMPLOYER

In this incident, the mobile home park owner told the property manager to contact the plumber, who was on 

retainer at the trailer park, to fix the problem with the sewer line. The plumber (employer) then hired four day 

laborers from a local home supply store, one of whom was the victim. The plumber did not have a state-issued

plumbing contractor’s license (C-36). The plumber had been self-employed since 1993 and had no employees. 

The plumber’s primary language was English, but he could speak some Spanish. He had performed 

maintenance and plumbing work for several years at the mobile home park. It is not known if the plumber had 

performed sewer repair and/or trenching work prior to the incident. 

WRITTEN SAFETY PROGRAMS and TRAINING

The plumber did not have a written safety or injury and illness prevention program (IIPP). No formal training 

about trenching was provided to the victim. It is not known if the property owner had procedures or protocols 

to identify and hire a plumbing contractor qualified to perform sewer repair.

WORKER INFORMATION

The victim was a 34-year-old male Hispanic day laborer who was hired by the plumber to dig a trench to 

expose a sewer line that needed repair. Three other day laborers were also hired by the plumber for this 

task. The victim’s primary language was Spanish. It is not known what prior work the victim had 

performed, or how much experience he had in trenching and safety procedures. 

INCIDENT SCENE

The incident scene was a walkthrough between mobile home residences where a trench was being dug 

to repair a sewer line (Exhibits 1 & 2). The trench was parallel to a mobile home and approximately four 

ft. wide, 30 ft. long, and eight ft. deep. There was also a water line in the trench (running parallel)

approximately three feet below surface level.

REPORT#: 2014-02 Page 3 
The incident location looking east (Exhibit 1) and looking west (Exhibit 2). At the time the photos were 

taken, the trench had been covered with tiles and concrete. Photos by CA/FACE program.

WEATHER

The weather on the day and time of the incident was approximately 75 degrees Fahrenheit, with a southernly 

average wind speed of about 7 mph [Weather Underground]. The weather is not believed to have been a 

contributing factor in this incident. 

INVESTIGATION

Sometime prior to the incident, tenants of the mobile home park notified the property manager about a 

sewer line problem. According to the plumber, he was asked by the property manager to perform the 

repair and began trenching work to uncover the sewer line on September 12, 2022. No permits were 

obtained from the local municipal authorities, as is required. The plumber hired four day laborers to dig 

the trench. Because of restricted space, the trench had to be dug with shovels. It is not known if the 

plumber knew the depth of the sewer line, soil composition, and presence of other utilities (including 

water lines), or how he identified the location of the sewer line. The trench was dug without shoring. The 

plumber was onsite, but not at the location of the sewer line when the incident occurred. In the process 

of digging the trench, a three-inch water line was exposed that was approximately three feet below 

grade and ran the length of the trench. No attempt was made to shut the water line off before work 

REPORT#: 22CA003 Page 4 
began, or once it was uncovered. At approximately 11 a.m., as two laborers were in the trench about 

eight feet below grade, the exposed water line above them suddenly broke and began filling the trench 

with water and dirt that was being knocked loose from the pressurized water. When the two day laborers 

above the trench witnessed this, they immediately attempted to rescue their co-workers. The water and 

mud were already up to the chest of the trapped laborers when the two co-workers above the trench 

tried to pull them out. It took approximately ten minutes before one of the laborers was pulled from the 

mud-filled trench. Unfortunately, the victim was completely submerged under the water and mud and 

was not able to be lifted out by co-workers (Exhibit 3). There was an unsecured ladder in the trench for 

egress and ingress, but it was not able to be used in the attempted rescue of the trapped workers.

Exhibit 3. The trench after the water was removed. Photo by CA/FACE program. 

Multiple fire and rescue departments arrived on the scene. The fire department removed the water from 

the trench with a vacuum. The victim was finally extracted from the trench after eight hours and

pronounced dead by paramedics.

CAUSE OF DEATH 

The county coroner listed traumatic asphyxia as the cause of death. 

REPORT#: 22CA003 Page 5 
CONTRIBUTING FACTORS 

Occupational injuries and fatalities are often the result of one or more contributing factors or key events in a 

larger sequence of events that ultimately result in the injury or fatality. CA/FACE investigators identified the 

following issues as key contributing factors in this incident:

• Lack of competent person onsite.

• Permits were not requested or issued for the work being performed.

• Workers were in an eight-foot-deep trench with no shoring.

• Water line was not turned off before or during work. 

• Lack of training for workers in trenching safety. 

RECOMMENDATIONS/DISCUSSION

The CA/FACE investigator determined that, in order to prevent similar incidents, property owners and 

plumbing contractors should:

Recommendation #1: Ensure that trenches five feet deep or greater are properly shored, shielded, or sloped.

Discussion: In this incident, the victim was working in an unprotected trench with a depth of eight feet. Any 

employee in a trench, five feet deep or more, is required to be protected from cave-ins by an adequate 

protective system. For all trenches or excavations five feet or deeper into which any person is required to 

descend, Cal/OSHA requires a permit. For any trench at risk of cave-in, Cal/OSHA requires sloping, benching, 

shoring, or shielding to protect workers from cave-ins.1 A qualified licensed contractor will also ensure that 

trenches five feet deep or more are properly shored, sloped, or shielded. The type of protective system, 

support system, or shield system used would be determined by the soil conditions found in the excavation. 

This is usually determined by the employer, competent person, or a licensed engineer. In this incident, the 

protective system should have included a trench shield (also known as a trench box), shoring, or a 

combination of shoring and shielding. Sloping would not have been appropriate because of the limited space 

within the motor home park. Employers can also consult tables located in the appendices of the Cal/OSHA 

Excavation Standard (CCR, Title 8, Subchapter 4, Article 6) that detail the protection required based upon the 

type of soil and environmental conditions present at the site. In addition, employers can consult with 

manufacturers of protective systems to obtain detailed guidance for the appropriate use of this equipment. In 

this incident, no protective system had been placed at any point in the trench. Had the trench been properly 

shored or shielded, this incident could have been prevented.

Recommendation #2: Ensure that the trench is inspected by a competent person.

Discussion: Many hazards are associated with excavating and trenching operations, including cave-ins and 

changes in environmental and physical conditions. Contractors who are licensed to perform excavation and 

trenching work are required to have a competent person who performs the necessary daily inspections of 

1 §1541. General Requirements.

REPORT#: 22CA003 Page 6 
excavations, adjacent areas, and the protective systems that are necessary and required. When employees are 

required to work in trenches deeper than five feet, a competent person is required to be onsite. Cal/OSHA 

defines a competent person 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” 2.

In this context, a competent person has:

• 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.

• The authority to take prompt corrective action on the job as conditions warrant.

A competent person must also inspect the trench and protective systems daily before the start of work and 

throughout the day as conditions change. In this incident, the plumber was not a competent person or 

knowledgeable about the proper procedures for trenching. Had a competent person been onsite and made 

daily inspections, the workers would not have been allowed to enter the unprotected trench and continue 

working with a pressurized water line exposed, possibly preventing this incident. 

Recommendation #3: Ensure that a licensed plumbing contractor is used to perform trenching and 

excavation work.

Discussion: In this incident, the property owner of the mobile home park hired a plumber to repair an 

underground sewer line. The plumber was not a licensed (C-36) plumbing contractor, and his primary 

responsibility over the years was to perform general plumbing maintenance for the mobile home park. The 

plumber did not request or obtain a permit from the local public works department to proceed with the 

excavation. In this incident, the plumber proceeded with the trench excavation without adequate knowledge 

of appropriate safety procedures or assessment of underground utilities including water lines. The trench was 

excavated to a depth of eight feet without shoring, and the water line was not shut off. If a trench is planned, 

it is necessary to shut off all utilities near the trench before the start of work. If the property owner had hired 

a licensed plumbing contractor to perform the sewer repair, a permit would likely have been obtained, proper 

shoring would have been used, the water line would have been shut off, and this incident could have been 

prevented. 

Recommendation #4: Ensure that day laborers are properly trained on hazards associated with working in a 

trench.

Discussion: In this incident, the day laborers hired by the plumber were never properly trained on the hazards 

of working within an unprotected 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. Day laborers include undocumented immigrants who are unable 

2 Subchapter 4. Construction Safety Orders, Article 2. Definitions, §1504. Definitions.

REPORT#: 22CA003 Page 7 
to gain formal employment because of their legal status. Day laborers often are in the position where they 

need to perform any work regardless of potential hazards that may be present on the job site and may not be 

aware of or able to notify their employers if they are concerned about working conditions. Most day laborers 

have received little, if any, safety training in the work they are hired to perform.

Employers who hire day laborers to perform hazardous work are responsible to provide them with a safe and 

healthy work environment. If an employer hires a worker, they are also responsible for providing workers’ 

compensation insurance. They must also ensure that day laborers are capable of understanding and 

performing all the safety aspects related to their work. Organizations that offer workplace safety training to 

day laborers include the Construction Safety Council (CSC), La Raza Centro Legal Program in San Francisco, the 

City of Los Angeles Day Laborer Centers, Instituto de Educación Popular del Sur de California (IDEPSCA), and 

the National Day Laborer Organizing Network (NDLON). Day laborers who have undergone such training are 

more likely to be familiar with and implement safe work practices. Likewise, property management companies 

who use licensed contractors for the specific type of work to be performed are more likely to be assured that 

employees are trained and are familiar with safe work practices. Employers should ensure the understanding 

and implementation of safe work practices by employees, including testing and on-the-job observation.

(T8CCR §3203. Injury and Illness Prevention Program).

Employers who hire non-English speaking workers should identify the languages spoken, and then design and 

implement a multiple-language safety program for employees. The safety program should be developed at a 

level that corresponds with the language and literacy level of the workforce, and in a form and manner that 

the workers understand. This program should explain a worker's rights to protection in the workplace, safe 

work practices workers are expected to adhere to, specific safety protection for all tasks performed, ways to 

identify and avoid hazards, and who they should contact when safety and health issues arise. 

DISCLAIMER

Mention of any company or product does not constitute endorsement by CA/FACE and the National Institute 

for Occupational Safety and Health (NIOSH). In addition, citations to websites external to CA/FACE and NIOSH 

do not constitute NIOSH endorsement of the sponsoring organizations or their programs or products. 

Furthermore, CA/FACE and NIOSH are not responsible for the content of these websites. All web addresses 

referenced in this document were accessible as of the publication date.

REFERENCES 

Tailgate/Toolbox Topics-Trenching Safety, Division of Occupational Safety and Health California Department of 

Industrial Relations TT-8: Revised May 2011

National Institute of Occupational Safety and Health NIOSH) Publication No. 2011—208 (Supersedes 2011–180) 

Preventing Worker Deaths from Trench Cave-ins

REPORT#: 22CA003 Page 8 
Cal/OSHA - Title 8 Regulations

T8CCR §341. (d) (5) (A) Permit Requirements. Oakland, California. Cal/OSHA/Division of Occupational Safety 

and Health.

T8CCR §3203. Injury and Illness Prevention Program. Oakland, California. Cal/OSHA/Division of Occupational 

Safety and Health.

T8CCR § 1539. Permits. Oakland, California. Cal/OSHA/Division of Occupational Safety and Health.

T8CCR § 1540 Excavations. Oakland, California. Cal/OSHA/Division of Occupational Safety and Health.

T8CCR § 1541 General Requirements. Oakland, California. Cal/OSHA/Division of Occupational Safety and 

Health.

T8CCR § 1541.1 Requirements for Protective Systems - Appendix A thru F. Oakland, California. 

Cal/OSHA/Division of Occupational Safety and Health.

T8CCR § 1542 Shafts. Oakland, California. Cal/OSHA/Division of Occupational Safety and Health. 

T8CCR § 1543 Cofferdams. Oakland, California. Cal/OSHA/Division of Occupational Safety and Health.

INVESTIGATOR INFORMATION

This investigation was conducted and authored by Hank Cierpich, Fatality Investigator/Consultant. Additional 

contributions to the report were provided by Robert Harrison, MD, MPH, CDPH FACE Project Officer; Laura 

Styles, MPH, FACE Research Scientist; and Glenn Shor, PhD, Cal/OSHA CFOI Program.

REPORT#: 22CA003 Page 9