When it comes to construction activities, trenching and excavation are the most inherently dangerous operations on a jobsite. No matter the nature of the work or the depth, excavations are unstable. A friend once told me that as soon as that cut is made into the earth, “Mother Nature wants to remake herself and cave back in.” 

Trench collapses are the cause of dozens of fatalities and hundreds of injuries each year. Other potential related hazards include falls, falling loads, hazardous atmospheres and incidents involving mobile equipment. In addition, the absence of protective systems such as shoring, shielding (trench boxes) and sloping/benching is frequently cited by Occupational Safety and Health Organization compliance officers. 

Pre-planning

For these reasons, pre-planning is paramount in excavation work. In addition, the OSHA standards addressing excavations (29 CFR 1926, Subpart P) mandates the involvement of a designated “competent person” to lead the operation by mastering OSHA regulations and recognizing existing and potential hazards.

OSHA defines a competent person as “an individual who is capable of identifying existing and predictable hazards or working conditions that are hazardous, unsanitary, or dangerous to workers, soil types and protective systems required, and who is authorized to take prompt corrective measures to eliminate these hazards and conditions.” 

Therefore, the competent person makes daily assessments and decisions that directly impact the health and safety of their fellow workers. In addition, whom you designate as the competent person is a critical decision as an employer. 

During my years as an onsite construction safety manager and corporate safety trainer, I have met many designated competent persons. While most are experienced and dedicated to maintaining safe operations, others have just been placed in the wrong position. 

Here are several examples of designated competent persons demonstrating that maybe they are not so competent after all. 

• It’s Okay, the Trench Box Is Just Around the Corner  

I witnessed an experienced pipe layer – and also the contractor’s competent person on the jobsite – climb into an 8-foot-deep area outside of a trench box to pick up the tools he had left at the bottom. 

In his opinion, being within a few feet of the box was safe enough. In reality, a cave-in could have occurred with dire consequences. 

Working within a trench or excavation requires the use of some sort of protective system and employees must remain in it (OSHA 1926.652(a)). Trenches 5 feet deep or greater require a protective system, unless the excavation is made entirely in stable rock, which is uncommon.

Depending on the soil type and work activities, the competent person might even opt to have a protective system in excavations less than 5 feet deep. 

• I Can Smell A Cave-In or Collapse Before It Happens

While that would be an amazing skill, this claim is highly dubious, Instead, competent persons are tasked with daily inspections of excavations, the adjacent areas and protective systems for evidence of a situation that could result in possible cave-ins, indications of failure of protective systems, hazardous atmospheres or other hazardous conditions ( 1926.651(k)(1)).

In addition, they may opt to test for atmospheric hazards such as low oxygen, hazardous fumes, and toxic gases when more than 4 feet in depth or if they suspect that the soil could be contaminated (1926.651(g)(1)(i)).

• I Can Outrun A Cave-in 

The walls of a trench can collapse suddenly, within seconds and with no warning. You can’t outrun it.

In addition to choosing the right protective system for the trench and performing daily inspections, the competent person must also ensure that there are ladders, steps, ramps, or other safe means of egress for workers working in trench excavations four feet or deeper.

Also, the means of egress must be located so as not to require workers to travel more than 25 feet laterally within the trench (1926.651(c)(2)).

• This Type of Soil Won’t Hurt You

Yes it will. One cubic foot of soil can weigh from 110 to 140 pounds or more, and 1 cubic meter (35.3 cubic feet) of soil can weigh more than 3,000 pounds or approximately the weight of a small car. Furthermore, fatalities can occur even if the soil doesn’t cover the employee completely. These are completely preventable. 

• I Can Classify That Soil Just By Eye-Balling It

The competent person is required to perform at least one visual and one manual test as a basis for classifying the soil. The soil type is then used to select the proper shielding, shoring protective system, or the proper sloping technique that will protect workers.

For these reasons, proper training and experience are critical when choosing the right person to oversee this operation. Subpart P, Appendix A is a great resource as it describes methods of classifying soils based on site and environmental conditions.

• Backfilling a Trench is Best Conducted While In It

More than once, I have witnessed an employee standing at the bottom of an unprotected trench directing the backhoe operator during the backfill process. OSHA’s excavation standards clearly state that employees shall not work under suspended or raised loads and materials.

Here, the best hazard control is to eliminate it all together. In this case, the coordination of backfilling can be done safely from outside of the trench. 

• In the Event of an Emergency, my Backhoe Operator Can Rescue Me 

One of my students described how his backhoe operator not only dug him out of a collapsing trench, but pulled him to safety.

This story seemed to be a bit of a tall tale to everyone in class. Even if it were true, this is a potentially treacherous and ineffective rescue plan. It would be difficult for even the best operator to dig around you without also risking striking you in the process. 

Instead, why not prevent the collapse from the beginning and reduce your risks of injury or a fatality by having a carefully thought out trenching and excavation plan executed by a designated, and truly competent, employee. 

About the author: Valerie Stakes provides safety training and site safety management for construction and manufacturing industries and has served as an instructor at OSHA Training Institute at UC San Diego. She was also the managing editor of Contracting Business magazine for eight years.