The soil itself poses the greatest threat to life safety
The Bureau of Labor Statistics (BLS, www.bls.gov) reports that trenching and excavation incidents account for at least 25 fatalities each year in the US. Work crews and equipment operators confront a myriad of hazards including underground utilities, trench cave-ins, and being struck by objects. The soil itself poses the greatest threat to life safety! Accordingly, trenching and excavation demand proper training, advanced planning, and constant monitoring of the work area, environmental conditions, and weather events — both forecast events and actual outcomes or ground truth.
Need to correlate site conditions with weather events
A recent article “Three Keys to Trenching and Excavation Safety” published by the American Society of Safety Professionals (ASSP, www.assp.org) highlights the need for constant site and weather monitoring during trenching and excavation. Contractors must determine how the continuous changes to the job site can impact safety. Some of the many continuous changes include soil factors and weather events. A member of the ANSI/ASSP A10 Committee confirms the need to correlate site conditions with weather events, such as thunderstorms, precipitation, temperature, and frost.
Freezing and thawing can change the stability of the trench
For example, freezing and thawing can create voids in the soil, and change the stability of the trench. As a result of freezing and thawing events, natural pressures cause the soil to fill the voids back up. Contractors must exercise care when determining the protective measure to put in place before, during, and after trenching and excavation work. Protective measures include structures, sloping, and benching. The data-driven ANSI/ASSP A10.12 standard, and other trenching and excavation safety standards, help protect work crews on-site from job hazards such as trench cave-ins.
Before, during, and after trenching and excavation work, contractors must assess the following data and dimensions following ANSI/ASSP A10.12 or other relevant standards:
- Provide a means of access and egress in trenches that are 4 ft. or more in depth to require no more than 25 ft. of lateral travel for workers.
- Keep spoil piles at least 2 ft. from the edge of a trench.
- Trenches 5 ft. or more in depth require a protective structure.
- Trenches 6 ft. or more in depth require fall protection.
- Trenches greater than 20 ft. in depth require a professional engineer to review the protection of structures in place.
American Society of Safety Professionals ANSI/ASSP A10.12-1998 (R2016) Safety Requirements for Excavation. This standard applies to all open excavations made in the earth’s surface that require worker and/or property protection. Excavations are defined to include trenches. Employees in an excavation shall be protected from cave-ins by an adequate protective system designed by a registered professional engineer. This standard provides the details to protect the workers.
(Source: “Three Keys to Trenching and Excavation Safety.” American Society of Safety Professionals, 10 Aug. 2020, www.assp.org/news-and-articles/2020/08/10/three-keys-to-trenching-and-excavation-safety.)
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