10 Tips to Trench and Excavate Safely
BY AsphaltPro Staff
On April 16, 2019, 26-year-old Christopher Ramirez and 41-year-old Jorge Valadez were working in a 15-foot-deep trench installing utilities for a new neighborhood in Windsor, Colorado, when the trench suddenly collapsed. Beneath 8 tons of dirt, Ramirez was somehow able to breathe for hours, speaking to rescue workers through PVC pipe and later a microphone. Before Ramirez passed away, he was also able to say goodbye to his wife, who shortly afterward gave birth to their son.
“[That story] drives us to this day,” said Perry Silvey during a recent webinar about trench safety presented by the Center for Construction Research and Training (CPWR). Silvey is the safety manager of BT Construction, Henderson, Colorado, and also an active member of the Trenching and Excavation Safety Task Force (TEST), an organization founded one week after the event occurred.
Last year, the Occupational Safety and Health Administration (OSHA) announced that there would be enhanced enforcement initiatives and outreach programs focused on trench safety following an increase in trench collapse fatalities to 39 people in 2022.
According to Nicholas DeJesse, assistant regional administrator of OSHA’s Philadelphia regional office, the increase in trench collapse fatalities may be a result of an overall increase in work being performed as a result of infrastructure spending and age-related wear on underground utilities. “We’ve also seen a lack of education, a lack of training, and a lack of having a person [on-site] who understands soil analysis, protective systems, spoil piles and things of that nature,” DeJesse said.
That’s why the CPWR webinar dug into some best practices for staying safe while digging, inviting Douglas Trout, a medical officer with the Office of Construction, Safety and Health at the National Institute for Occupational Safety and Health (NIOSH), and Phillippe Falkner, safety director at Ed Bell Construction Company, to highlight the following best practices.
1. Train & Designate Competencies
It’s important for employers to train and designate a competent person to ensure safety measures are in place. “A competent person is one who understands OSHA regulations, can recognize hazards, and is authorized to correct them,” Trout said. There should also be a competent person to evaluate the soil to determine its stability.
OSHA also requires that all excavations 5 feet deep or greater make use of protective system options, which can include sloping or benching the ground, shoring the trench with supports, or shielding the trench, for example using a trench box. “Employers should have a competent person to determine what type of protective system will be used for the job and schedule the steps needed to have the system complete and in place before workers enter,” Trout said.
2. Cross Train Competencies
“A lot of contractors focus on getting a handful of people trained well enough that they can serve as competent persons,” Falkner said. However, he prefers training as many people as possible and encouraging discussion on the job site. “Even on a small job site where the designated competent person is there all the time and focused 100% of the time, he still can’t see every angle of that excavation.”
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3. Train the Whole Trenching Team
It’s also the employer’s responsibility to ensure workers involved in the job are properly trained, Trout said.
Falkner puts staff through an abbreviated trench safety training session multiple times a year. “Everyone who’s expected to go into a trench or be adjacent to a trench goes through that training,” he said. “If you go into a trench, you ought to have a working knowledge of what that designated competent person is looking for.”
And training can’t be irregular or perfunctory. “You can’t check the box for trench protection training once a year and move on. It needs to be a regular, recurring training topic,” he said. “You’ve got to communicate your expectations of what you want done and what they need to do to safely get the work done—and make sure you’re providing them the resources they need to do it.”
4. Plan Ahead
Of course, employers should use processes to determine the exact location and depth of utilities before digging, Trout said (811 is the national Call-Before-You-Dig number). They should also plan the job layout to identify safe locations away from the trench for spoil piles and heavy equipment routes.
However, Falkner also stresses the importance of planning when it comes to determining soil classification and appropriate protection systems before digging begins. “Having this done well in advance is part of the critical planning process,” he said.
It’s also important to develop a trench emergency action plan outlining steps to be taken and appropriate emergency contact information. “OSHA also requires employers to provide ladders, steps, ramps or other safe means of egress for workers working in trench excavations 4 feet deep or deeper,” Trout said.
Think Outside the Box—Sometimes: Falkner said that while trench boxes are the most common protection system, there are some conditions where they aren’t ideal. But, because of familiarity with trench boxes, contractors will try to make them work in suboptimal conditions. “You have to figure out what systems are available for which conditions,” he said. “Talk to your competent person, talk to people experienced with engineering plans, seek the help of a registered engineer if that’s what it takes. Talk to your vendors that deal in trench protection.”
5. Consider Other Contractors
“Planning is not just in-house; you have to communicate with everyone else on the job site,” Falkner said. “Your operation may have haul routes designated and stockpiles planned and fall protection in place, but if you’re not the only contractor on site, you need to be planning and coordinating with the other people on that site to make sure they don’t get hurt by your excavation or they don’t hurt your people and your excavation.”
6. Keep People Up Top Safe
“There are a number of people that will come to see what’s going on with the excavation or play a role [in the job] that doesn’t have them down [in the trench],” Falkner said. The edge of a trench is no different than working near any other fall hazard. “You need to make sure the people up top are also protected.”
Another way to prevent trench collapses and therefore fatalities is to use alternative methods where feasible, Trout said. This may include directional boring, relining the pipe (including cured-in-place pipe), pipe ramming, utility tunneling and pipe jacking.
7. Consider Other Hazards
Falkner stresses the importance of keeping the big picture in sight. “It’s easy to get tunnel vision with collapse prevention that we forget about other risks,” Falkner said. “Especially if you’re on a complex trench set up that’s taking a lot of engineering, planning and teamwork.”
“I’ve seen it happen one too many times where a team has done everything correctly [to prevent trench collapse],” Falkner said, but they might overlook atmospheric hazards such as gas. These hazards need to be checked at the start of shift and monitored throughout the day.
It’s also important to be mindful of critical load plans. “We’re building these trenches generally to put things in the ground or take them out,” Falkner said. “Oftentimes equipment is a bit further back from the trench than what would normally be done to ensure a safe excavation, so you may have to account for things that aren’t normally a critical lift.”
He also reminds us that workers in the trench will have more limited escape routes. “It’s not as easy to get away from problems with the lifted load as it is on even ground,” he said. “And make sure you’re still placing your fall protection where applicable.”
8. Check Every Day & Throughout the Day
Trout stresses the importance of having your designated competent person inspect the excavation, adjacent areas and protective systems each day before work, but also as needed throughout a shift, and specifically after every rain storm.
In Falkner’s experience, most contractors pay attention to these aspects of trench safety at the start of the job, but this wanes as the job continues. For the crew that moves protection systems “as they go,” they could be moving through changing soil conditions and changing construction sites, Falkner reminds us.
“There’s never a point where we get to check that box and say, ‘Okay, I’m done with that step for today,’” Falkner said.
9. Give Employees Authority
“Make sure your employees have the right and the expectation to stop work if something doesn’t look right,” Falkner said. “Maybe something was working this morning and now the job is a whole different ball game. It’s okay to stop and reevaluate.”
He’s heard employees time and again say they didn’t feel like they had time to follow best practices because they were behind schedule. “You need to express that if something’s not right, it’s absolutely okay to take a knee until it is,” Falkner said. “Make sure you’re preaching to them that production takes that backseat to safety.”
10. Think Maximally, not Minimally
“Instead of approaching things with an attitude of ‘What’s the minimum I can do that meets the OSHA guidelines,’” Falkner said, “you absolutely need to go to the other end of that spectrum and say, ‘What’s absolutely the maximum I can do to protect my people and protect the workplace?’”
The Bottom Line
“We all have to keep in mind that there’s almost no excavation we do where you’re not at some risk for injury or death,” Falkner said. However, Trout said, the hazards associated with trench work and excavation are defined and preventable.
According to Silvey, one aspect of the trench collapse in Colorado that stood out to him was that there had been a trench box on site that had not been in use. “Of course, our question is always ‘Why?,’” he said. “We continue to ask that question and we continue to try to find solutions and try to find creative ways to help folks make the right decisions.”
“We’re here [at this webinar] because construction workers are at risk of death or serious injury if they enter an unprotected trench,” Trout said. That’s why it’s so important to take a maximalist attitude to trench safety. “If you’re just trying to get by, it may not be a problem today or tomorrow,” Falkner said, “but eventually it will catch up with you.”
Get Involved: Silvey encourages anyone interested in trench safety to join the Trenching and Excavation Safety Task Force, use the hashtag #thinkinsidethebox to join the conversation on social media, reach out at thinkinsidethebox@gmail.com, or learn more at thinkinsidethebox.info/.
Digging In a Drought
At the end of the webinar, one attendee asked about the effects of extreme drought on soil conditions, as Texas experienced in 2023. Falkner said the extreme drought and extreme temperatures fractured the soil, adding that there’s likely more instability and variability of soil conditions.
“When soils dry, they start to pull away from each other and create fissures and cracks,” Silvey said, “and you can’t see through the dirt to know where those are.” Falkner said those fractures can run 10 to 15 feet deep, “especially when you get these expansive clay soils down here.”
Falkner said Ed Bell Construction is taking a more cautionary approach in light of these events. “If you’re on the fence between A and B or B and C, you just need to be more cautionary,” he added.
Silvey seconds that approach. “You should look at it like everything is a Type C soil,” he said. “It’s not a matter of if it will collapse, it’s a matter of when it will collapse.” He added freeze/thaw cycles can have a similar effect. “The soil expands when it freezes and starts to break apart as it thaws, creating those large fissures that could cause collapse as well,” Silvey said. “Be a little more conservative. Take the extra precaution.”