Dangling objects hanging from cranes, dizzying fall hazards, and heavy equipment injuries. These are common dangers on construction and demolition sites. But a less obvious hazard lurks underfoot: the trench.
In the past few months, several construction firms have been cited for failing to follow trench safety standards. However, lackluster trench safety is nothing new. According to the Bureau of Labor Statistics, 38 construction workers died in trench cave-ins and excavations in 2000 alone. Today, we’re taking a look at how trench injuries can be avoided by the industrial demolition contractor.
How to Avoid Trench-Related Injuries on a Job Site
Provide proper cave-in protection. Deep trenches are liable to collapse suddenly, crushing or even burying workers. The heavy weight of soil—a cubic yard can weigh more than 3,000 pounds—creates such a strong force upon collapse that workers may be unable to take breath. Suffocation is a common cause of death in trench accidents. Especially heavy soil may crush the body in seconds. OSHA reports that the majority of trench and excavation deaths can be prevented with proper protection systems in place.
Select cave-in protection according to soil conditions and trench depth. OSHA doesn’t require protective systems for trenches less than five feet deep, unless the competent contractor sees danger of collapse. Even four and a half feet of collapsing soil can cause deadly consequences. Trenches between 5 and 20 feet in depth always require protection, in the form of shoring, sheeting, shielding, sloping, or benching.
Shoring and Sheeting are mechanical, hydraulic, or timber-based systems that support the walls of a trench or excavation. Hydraulic aluminum shores, installed from above, are popular for shoring, as they are reusable and lightweight.
Shielding doesn’t thwart cave-ins, but instead protects workers should a collapse occur. In this category we find trench boxes, which are dragged along the length of the trench as work progresses (such as when laying down pipe).
Sloping and Benching involve cutting the trench walls at such an angle that there is little likelihood of collapse. Because these methods require plenty of space, they are less popular than shoring, sheeting, and shielding.
Check safety of work on a daily basis. OSHA requires a competent person to check the condition of trenching and excavations daily. Workers should not enter the trench before the day’s inspection has been done. The competent person must check soil condition, protective system functionality, safety of trench access points, and more, such as regular inspection of hidden utility lines.
Train workers and managers on proper trench safety. Cave-in prevention should be a familiar aspect of working culture on construction sites. Workers and employers should be well aware of collapse hazards. Educational programs can include watching informative videos, reviewing OSHA standards, and the discussion of rental options for trench protection, such as trench box rental.
In addition to the human tragedy of trench collapse, contractors who fail to provide proper trench protection may face fines and even imprisonment. As an example, in a 2002 case, US vs. Walter Marble, the construction company owner Marble was found guilty of covering up the death of a worker killed in a trench collapse. Marble was sentenced to five months in prison, five months of home confinement, two years of supervised release, plus $3,000 in fines. This was for a single trench violation; in 2002 OSHA proposed $110,000 in fines for two Massachusetts contractors who repeatedly failed to protect workers from possible cave-ins.
On demolition and construction sites, trench safety is key. As we’ve seen, contractors have several choices for trench protection devices. With the proper education and procedures in place, contractors can prevent trench-related injuries and fatalities on job sites.
[photo by: Aaron Volkening on Flickr via CC License]