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Hidden dangers of excavation and trenching

November 3, 2015
 / Safety / , / Operations / 

Excavation and trenching are both vital operations in the construction industry. They also happen to be two of the most dangerous. According to the National Institute for Occupational Safety and Health, 350 workers were killed in trenching or excavation accidents between 2000 and 2009, an average of 35 per year. Most of these occurred during work on residential utility lines, at depths of less than 10 feet.

"One cubic yard of soil weighs as much as 3,000 pounds."

This underscores the hidden threat of trench collapse. While such a shallow depth may seem harmless, just one cubic yard of soil weighs as much as 3,000 pounds, according to the NIOSH, enough to crush or suffocate easily. And even small amounts of dirt can fall without any warning whatsoever. The risks inherent in trenching and excavation are compounded by the dangers of working in confined spaces, as well. The Occupational Safety and Health Administration and the NIOSH have detailed and newly updated rules and regulations on these operations. With construction ramping up around the country, workers and supervisors need to be thoroughly informed on the dangers of trenches and excavations, and how to implement the proper safety precautions.

Case studies
Real-world examples provided by NIOSH demonstrated the persistent dangers of trench work. In 2003, a 38-year-old worker was killed when an 8-foot-high trench he was working in collapsed. While at least two people competent in trench and excavation safety were present, none of the standard procedures were followed because the worker was supposed to be in the trench for "only a few minutes." Indeed, upon entering the trench to saw a pipe casing, he was buried by soil when the trench collapsed just minutes afterward.

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What every worker should know about excavation and trenching.

In 2006, a Hispanic worker with five years of experience in construction was killed when the 9-foot-deep trench he was working in collapsed, according to NIOSH. The victim and four other workers on the scene all spoke very little English. The company they worked for did not have a written safety program, nor any supervisor on site knowledgeable in trench safety.

These two cases show how a variety of seemingly minor or innocuous factors contributed to fatal accidents. In the first case, the proper safety preparations were not followed out of the assumption that the risk was minimal. In the second case, the safety precautions may have not even been known to the workers due to the language barrier. This helps to highlight the primary ways employers can work to prevent these kinds of accidents.

Taking the right steps
Exceptional safety training is the first and most important step to take in order to prevent trench collapses. First, the basics of trench stabilizers should be known. To prevent cave-ins, OSHA recommended three safety measures to implement: sloping or benching, supporting the sides of the trench and shielding the work area. Exactly which procedures are used depends on various characteristics of the work site, like the soil condition, depth of the trench and weather conditions. OSHA has detailed specifications to which slope designs and shields should adhere.

             Excavation operations require several specialized protocols to ensure worker safety.

Before beginning any dig, workers need to take some other important precautions. A certified expert should be on hand to verify the quality of the soil and determine the risk of caving. In some instances, the soil will be stable enough to allow work with minimal safeguards in place, but only a professional soil analysis can determine this. It is also essential to call 811, the hotline for utility digging services. This should be done a few days in advance of beginning digging, according to Call811.com. A certified inspector will arrive on site and mark areas where various utility lines are buried. Someone on site should be designated as a supervisor and plan other details like the location of equipment, the type of protection system to be used and ensuring all workers entering the trench are aware of every necessary safety regulation.

Working in a trench could also be considered a confined space. OSHA has recently revamped its regulations on confined spaces in construction into a more comprehensive set of guidelines. According to the filing of these new rules in the Federal Register, OSHA did not have more than a single training provision concerning confined spaces dating back to 1979. These provisions went into effect Aug. 3 and thus are relatively new. A confined space is classified as any area in which workers must be present but their movement is constricted. Spaces are considered "permit-required confined spaces" when they have one of the following characteristics:

  • Potentially "hazardous atmosphere"
  • Contains "material that could engulf the entrant"
  • Walls conducive to trapping or asphyxiating a worker
  • Contains any other possible health hazard (exposed wires, heat stress, etc)

In these cases, special considerations must be taken to minimize risk. OSHA has a full list of strategies and guidelines pertaining the final rule on confined spaces on its official website.

Communication is key
With these safety basics in mind, the next step is communicating them to workers, and ensuring safety standards are recognized on the job. As the case involving Hispanic workers demonstrated, safety regulations need to be communicated in a way that everyone can understand. If just one worker is unaware of the proper safety operations, it could jeopardize the safety of the rest of the crew. Toolbox talks, the standard for safety training, are often available in Spanish as well as English. These may take the form as videos as well, making the information and knowledge contained in them easily accessible to workers of many backgrounds. The numerous construction safety products available today make the job of safety standards compliance easier today than ever before.

Using new mobile apps for construction professionals, the training and compliance process can become incredibly streamlined. Managers now have a reliable way to integrate toolbox talks and videos with safety checklists to perform before, during and after various operations. Utilizing the latest technology, every construction worksite has the potential to remain injury-free, increasing productivity and most importantly, the health of everyone.

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