NUCA Safety Management: Three S’s of Trench Safety


George Kennedy is NUCA Vice President of Safety.

A safe trench depends on one of the three S’s of trench safety — sloping, shoring or shielding. Cave-ins occur too often, and if workers are in the trench, someone will probably be injured or killed. The sad part is that these accidents are preventable when a proper protective system, such as sloping, shoring or shielding (trench box), is used. There is a forth S which fits into the other three S’s and that is a system designed by a registered professional engineer such as slide rail system, beam and plate, sheet piling, sloping greater than 20 ft, etc.

We know that the number of deaths in trenches has dropped over the past 25 years since OSHA revised the excavation standard and NUCA introduced its Excavation Safety and Competent Person Training program. NUCA instructors and contractors can take pride in the fact that we have made a difference and helped reduce the number of deaths and injuries.

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We also know that it was not just training that made the difference. A number of factors have contributed to fewer injuries and deaths. Increased OSHA activity has definitely caused many contractors to pay more attention to compliance. Contractors who recognize the importance of and are using shoring and shielding whenever it is needed have made a difference. We also owe thanks to the manufacturers and distributors of protective systems, some of them associate members of NUCA, because they have responded and continue to respond to industry needs by providing an array of protective systems.

There is no good excuse for placing a worker in an unprotected trench. Some say it costs too much money to buy and use a protective system. However, experienced contractors like Ron Nunes, NUCA’s Past Chairman of the Board, say, “once the workers are trained to work safely and properly use the equipment, providing a safe place to work does not cost more.”

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Others say that a protective system is not necessary in a trench that will only be open for a short time. And the worst excuse of all is, “The worker only has to be in the trench for only a few minutes, so why go to all the trouble of installing a protective system?” Have they ever seen a trench wall cave-in and how fast it happens? BAM! That’s how fast it happens. I have heard many other excuses, but they are all nonsense. Try offering one of these dumb excuses to a grieving widow and her children or the mother of a worker who lost his or her life or was permanently disabled due to a cave-in. See what they have to say about worthless excuses. The fact is in an OSHA hearing or a court of law, none of these excuses will hold water.

We have placed a lot of emphasis on competent person training, but workers must also be trained to recognize excavation hazards and to refuse to work in unsafe excavations without fear of reprisal. According to OSHA regulations, workers must be trained to recognize and avoid unsafe conditions and to know the safety regulations applicable to their work. They should be encouraged to report unsafe conditions to their supervisors and/or safety director.

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The OSHA training requirements include the hazards associated with working in the trenches. Are your employees trained to recognize trench hazards? Do workers know they should never enter an unprotected trench more than 5-ft deep (4-ft in some states)? Or that they should never go outside the protective system, even for a moment? Or that the ladder must be set up inside the protective system and extend 3 ft above the point of access? What other hazards do they need to know about? Much of the information included in a good excavation safety and competent person training program should provide workers with this training. In fact, over the years many NUCA contractor members have chose to send not just the foreman or equipment operator but the entire crew to NUCA training programs to ensure the management team and the workers are all informed about the requirements. It is a good investment.
OSHA pulls no punches when it comes to excavations; just ask any contractor who has been inspected recently.

Excavations and trenching jobsites are still part of OSHA’s highly-emphasized program for construction. The first thing the compliance officer will ask is who is the competent person (CP)? The compliance officer will start by asking the CP some basic trench safety questions that every CP should know. The inspection will follow and the compliance officer will determine if the job is safe and if the CP is in fact competent. That determination will be based on what the officer observes. If a protective system is not in place or if workers are not working inside the protective system, mark my words, penalties will be issued for not using a protective system and for not having a competent person onsite.

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A Safe Way to Save Money

Companies involved in trenching and excavation realize true savings by using proper protective systems. However, some contractors and municipalities use so-called protective systems that are not properly engineered or rated for the work. Have you ever observed someone using a couple of sheets of plywood and a few 2x4s as a shoring system? In addition, systems are often misused. For example, an 8-ft tall trench box used in a 12-ft hole is being misused if not combined with sloping per the box manufacturer’s and OSHA standards. Likewise, when steel road plates are placed next to the trench box to extend its height or length, the box is being used improperly.

Although proper sloping of the excavation walls will provide an acceptable protective system, informed contractors realize that sloping is not necessarily cost-effective. The following are reasons why shoring and shielding save contractors money:

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Job planning is about safety and economics. Picking the right trench protective system for a particular job saves money. Having the equipment available onsite helps to ensure the crew works safely, speeds up production and lowers costs. Pre-engineered systems eliminate the guesswork and the cost of custom engineering. Modular shoring and shielding systems make installation fast and easy, without cutting, welding, nailing or other time-consuming methods. Depending on the size of the job, protective systems can be purchased and used over and over or rented for a specific project. Contractors can avoid unexpected expenses, penalties and accidents with thorough job safety planning.

Avoid costly damages and repairs. The cost of repairing existing utility lines or infrastructure damage because of improper trench wall support can be expensive. A cave-in not only endangers workers, it affects existing infrastructure adjacent to the trench.

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Reduce soil removal and replacement costs. A 10-ft deep, 4-ft wide, 50-ft long trench requires the removal of 74 cu yds of dirt if shoring or a trench box is used. If the same trench is sloped for type A soil, 139 cu yds must be removed. For type B soil, 185 cu yds would be removed and for type C, 278 cu yds. At a cost of approximately $2 per cu yd, just handling dirt will cost two, three or more likely four times as much as preparing a trench for shoring or shielding. Additional savings are attained when adding in filling, compacting and resurfacing. It’s cheaper and safer to purchase or rent some shoring or a shield depending on how often it will be used.

Reduce restoration costs. Restoring the surface of a trench can be expensive. Shoring and shielding will reduce the costs compared to sloping. For example, placing a 2-in. blacktop surface for the trench when using shoring or a shield would require 198 sq ft of asphalt; 945 sq ft if sloped in type A soil; 1,197 sq ft if sloped in type B soil; and 1,692 sq ft if sloped in type C soil. At an approximate cost of $80 per 100 sq ft, the savings are obvious and the cost of purchasing or renting shoring or a shield is recovered very quickly.

Reduce workers’ compensation claims. Workers’ compensation premiums are sky rocketing and are based on a company’s claims record. The greater the number and cost of claims will dramatically increase the premiums. Some companies pay far more for their insurance than their competitors because of claims. Higher insurance cost makes a company less competitive.

Avoid damage to adjacent property. Loss of adjacent property, curbs, sidewalks and ornamental ground cover are common costs when shoring or shields are not used. Undermining adjacent structural foundations can lead to expensive property damage claims, which can mean higher insurance premiums and more out-of-pocket costs such as downtime.

Reduce disposal costs. It is not uncommon these days for designers to insist that the same dirt that was removed from the hole not be used as backfill. Disposal of soil and debris is an expensive part of some projects. Reducing the amount of soil excavated eliminates unnecessary expenses.

Reduce unsafe conditions while increasing productivity. Crews working in unsafe excavations are not as productive as they could be. Unprotected workers work slowly when they have to keep a wary eye on unstable excavation walls. Also, the quality of work will improve.

Avoid large OSHA penalties, legal expenses and possible jail time. OSHA is in the process of adjusting penalties by as much as 70 to 80 percent. Serious violations are expected to increase to as much as $12,600 per violation. Willful violations, which are common when protective systems are not used, will be increased to as much as $126,000 per violation. Legal defense cost for citations can be tremendous. The money would be better spent on purchasing protective systems that can be used for 20 years.

Value of your freedom. What is it worth to you? A worker killed in an unprotected trench can and has resulted in manslaughter charges for owners or other upper-level managers. Not providing a protective system may appear to save money up front, but if a cave-in occurs, it jeopardizes the lives of employees, their families, your company’s reputation and your freedom.

Value of your livelihood. Companies have been put out of business because of their failure to provide a safe place to work. All it may take is a cave-in in an unprotected trench or excavation that results in one or more workers being killed or seriously injured. When incidents of this type happen, OSHA will show up and issue enormous penalties that are not covered by insurance. Behind OSHA are the lawyers of the families who will take legal action against your company, and if you think OSHA penalties are expensive, you’re in for a wakeup call because litigation can and has destroyed many companies.

Cave-in Protective Systems are the Way to Go

Using shoring or shielding is the law and will lower your costs and protect workers. Many NUCA associates manufacture, sell, distribute and rent properly engineered, reusable and cost-effective trench protective systems. Call these members, talk to them and find the systems that will work best for your crews and the type of work they are performing.

The cost of one death or serious accident could pay for all the shoring/shielding that you will ever use. If you determine sloping is the better way to go for your company that is fine too, as long as you slope the walls according to OSHA regulations. First and foremost, you must protect your workers from being buried alive or seriously injured by a cave-in.

To learn more about excavation safety training that’s available, visit for a list of NUCA’s Excavation Safety and Competent Person Training Instructors that are available throughout the United States. Many of them will travel to your location.

George Kennedy is NUCA Vice President of Safety. Tags: ,