Page 32 - Occupational Health & Safety, October 2019

CONSTRUCTION
bility), and more. Becoming a trench competent person requires hours of training including time in a trench evaluating circum- stances, learning how to classify soil types, and working with the safety equipment, as well as time spent in-classroom training.
Many often ask, does a competent person need to stand by the trench at all times? Absent any mitigating factors such as water accumulation, by law, the competent person does not need to be present at the trench at all times. However, he or she is ultimately responsible for making ongoing inspections to ensure compliance throughout the process. Furthermore, and to be quite frank, this is the wrong question to ask. The question I much prefer is, “At what point during the process do I get my competent person involved?”
The answer is: as early as possible.
Far too often the competent person is brought in after the trench has already been dug. Doing this hobbles your competent person’s ability to advise on technique and trench shape for optimal safety, provide direction as to which safety equipment should be used, and to properly assess the safety of the situation. Bringing your competent person into the fold before the trench has been dug enables that person to create a comprehensive preplan to guide ex- cavations, ensure the safety of workers, and protect your company from potential liability.
Preplans: Your Key to Safety
A big part of being safe is being prepared. Knowing as much as possible about the job or work site and the materials or equipment needed is a best practice, and building a preplan is an essential part of your competent person’s job. There are many things that OSHA recommends that companies should consider when building a pre- plan, including:
Traffic. OSHA requires that workers at sites near roadways, or other trafficked areas, wear hi-visibility vests. Also, the site must have a system, such as barriers, in place to prevent vehicles from rolling into the excavation/trench. Sometimes this also means road closure or traffic patterns changes. In addition, vibrations from nearby roads will make a trench more unstable and susceptible to collapse; a competent person will take this into account when as- sessing the safety of a trench.
Proximity and physical conditions of nearby structures. The presence of nearby structures or underground utility lines almost always means that the soil has been previously disturbed, and pre- viously disturbed soil cannot be classified as “Type A soil” (the saf- est kind for trenching); it is inherently more unstable than undis- turbed soil. Further, the proximity of structures such as buildings, the depth of their foundations, and whether the trench may experi- ence surcharge load from those foundations all factor into the com- petent person’s safety calculations. Finally, if a trench is deeper than 20 feet, or if the dig will impact another structure, OSHA mandates evaluation by a registered professional engineer.
Soil. During preplanning, the competent person will evaluate the surrounding soil type (classified as Stable Rock A, B or C). The soil will impact the type of trench that can be dug, the safety equip- ment that must be used to shore the trench, and more.
Surface and groundwater. Anyone who has dug a hole at the beach understands that the presence of water makes a trench in- herently unstable and more likely to collapse. Workers cannot le- gally enter a trench that has accumulated water unless there is a system in place to mitigate and the system is actively abating that
hazard. Furthermore, a competent person must monitor the drain- age of that water.
Weather and location of the water table. How likely a trench will accumulate water depends on many factors including the depth, water table (and in some areas, the tide), proximity to a storm drain or sewer system, weather and more. A competent person will consider factors such as these when creating a trench preplan.
Overhead and underground utilities. Again, the presence of utilities almost always indicates soil has been disturbed. In addi- tion, if digging above a water or sewer line, your risk of ruptur- ing the line can be high, which poses a very dangerous scenario: a 4,000-gallon per minute water line may rapidly fill your trench and possibly kill or entrap whoever is inside.
Construction materials/equipment/tools. OSHA requires that any materials, equipment, or machinery used near or over a trench project must be prevented from accidentally or inadvertent- ly falling into the trench. This is done by either barricading, stop logs, or active monitoring.
Conclusion
Nobody should die as a result of someone else’s perceived emergen- cy (whether that “emergency” is a loss of water supply to a building or the clock ticking on a hard bid job). But unfortunately, this hap- pens time and again.
It doesn’t matter whether you are the owner of a business or a new hire. Everyone on a job needs to take safety to heart and be empowered to speak up if they see a crack in the trench or if some- thing’s not right. The last thing anyone wants is someone saying, “I knew that would happen,” after a death. While regulatory require- ments can change, fundamental values do not change. Thus, during our training, the most important lesson we teach is that safety is not a requirement, it is an inherent value. When lives are a stake, anything less is unacceptable.
Tim Robson is Chief Instructor for Roco Rescue and longtime Rescue Team Manager, Rescue Squad Officer and Safety Officer for FEMA’s/ Department of Homeland Security New Mexico Task Force 1. Tim Robson was also a member of the Albuquerque Fire Department’s Heavy/Technical Rescue Team and witnessed the tragedy of trench deaths many times as a rescuer. Today he travels the country helping companies understand the perils of trenches and learn how to keep their workers safe as well as perform a trench rescue when needed. To date, he has helped enhance the trench safety programs of more than 50 companies and has taught over 50 courses.
28 Occupational Health & Safety | OCTOBER 2019
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