There’s a famous saying, “It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.” It’s commonly accredited to Mark Twain, but likely it's one of those quotes that change as people say it and eventually collapses upon itself over time.
No matter where the quote’s origins, it’s still true – especially in trench safety as hazards are born out of misinformation and false knowledge. OSHA’s webpage on trenching and excavation, reminds contractors that a safe plan includes provisions for safe entry/exit, cave-in protection, proper assessment of environmental hazards, keeping materials away from the edge, and ensure proper inspection.
According to its November 2024 report, the preliminary data showed a decrease in fatality investigations. Saying that the numbers were “promising evidence that stronger enforcement and collaboration with labor and management…is saving lives,” says Douglas Parker, assistant secretary for Occupational Safety and Health. Data shows that trench collapses have declined nearly 70 percent since 2022.
Excavation shoring is a science that involves complex engineering calculations, soil studies, not to mention a strong understanding of the impact of hydraulic loads, surcharges and vibrations on a temporary retaining structure. In an attempt to aid contractors and avoid requiring an engineer on every job, OSHA simplified the soil classification system in 1989. That same year they added that any deviation from provided options would need to be approved by a registered professional engineer (RPE). Shoring designs are very complex – there is no room to take a causal approach to trench excavation.
Bruce Magee, region product development manager of trench safety at United Rentals, explains that the false knowledge umbrella for trenching would include the following hazards.
- Improper sloping or benching configurations. There is a notion that the workers can modify the soil removal requirements to fit their work, often leaving one or more trench walls much more vertical than is allowable. Workers think they can develop their own design.
- Failure to understand when an engineer is required. Adjacent structures may be near an excavation, but when workers hear over and over again that an engineer is not needed because the trench is shallower than 20’, they proceed with that work until gravity causes the adjacent structure to fail.
- Workers/foremen/civil construction people that are not engineers erroneously think they can modify any existing system to fit their need, or can “MacGyver” something out of available parts on a jobsite. The truth is that OSHA is specific about what can be used, and no one other than a registered PE is authorized to modify a protective system.
- Trenches are not confined spaces. That is true, but that does not mean that it is never required to test an atmosphere for a hazardous gas. Fact is, according to OSHA and the Federal Register, when doing sewer work, or working in any area where hazardous atmospheres may develop, testing of the atmosphere is required. Every year there are fatalities due to asphyxiation in trenches.
Make No Mistake
United Rentals Inc.
There are restrictions and limitations within each of the options, but ANY deviation less strict than allowed will require written permission from an RPE.
“Now, the question turns to when these systems are needed,” says Magee. “Unless the excavation is made entirely in stable rock, one of these systems is required at 5 ft. of depth.” OSHA’s charts are good to 20 ft. but that is only when there is no extraordinary surcharge. Everything deeper will require a system approved by an RPE.
On that note, he reminds everyone that any use of a manufactured system not in conformance with tab data must be approved in writing by an RPE. This means that road plate or steel sheeting placed behind a box is not allowed without an RPE approval. Using half of a box at the end of the shield to seal off the end is not allowed without an RPE approval. Using road plate or steel sheeting at the end of a box or modifying a box is not allowed without an RPE approval.
“If you are using any of the options OSHA provides charts for, or using any manufactured system, and you must deviate from those limitations, no matter how deep you are working, such changes must be approved by an RPE,” says Magee. “If you are using a site-specific plan from an RPE, but must deviate from that plan, the engineer must provide written approval in advance of any change.”
What Can Contractors Do?
Be proactive. As contractors, it’s vital to know about and inform everybody of the potential hazards at the jobsite as well as the hazards surrounding the work being done. Everybody includes everyone – this means estimators, project managers, foremen, etc.
Get and provide accurate training on what to do about the hazards. Make sure that training is accurate. Find experts that you know will be truthful and honest.
United Rentals Inc.
What Can Equipment Rental Businesses Do?
Knowledge is key. It's recommended that equipment rental companies invest in the education and training for the team as well as the application of any relevant equipment (including the assembly and proper use of).
Guessing is never acceptable so be honest, especially when you don’t know the answer. “There will be times when any of us are asked questions technical in nature. So, if and when the rental service employee is asked a question they are not equipped to answer, those employees should be comfortable in saying they cannot answer the question but will get the customer someone that can,” says Magee.
Excavation work can be extremely dangerous. He adds, “Questions should be answered as if someone’s life depends on it because it does. Don’t tell your customer what they want to hear, tell them what they need to know.”
Training
In December 2024, United Rentals launched “Excavation Safety Training for Competent Persons Program” offering an interactive approach to teaching trench and excavation safety. Developed with Mosaic Learning, it was designed with engaging learning activities and simulation exercises to coincide with the United Rentals Trench Safety app that includes a slope calculator and other safety resources.
“Working below ground, and building underground structures and utilities is demanding and requires relevant up-to-date safety training. Leading-edge training takes the information and classroom lessons to the field, which helps promote safe and compliant jobsites,” says Todd Hayes, Region Vice President – Trench Safety, United Rentals. “Our revised program will help our customers foster a culture of safety, while reducing risks and improving jobsite results.”
As described by the company, the training helps those overseeing excavation safety, employers, and workers find a better understanding and apply OSHA Standard 29 CFR Part 1926 Subpart P. It goes beyond the basics, covering topics such as soil evaluation, protective systems, and interpretations of safety standards. Available through United Academy, the program offers flexible formats, including in-person classes, virtual instructor-led sessions, and e-learning.
