Trench & Excavation Safety

A construction company that had been in business since 1992 had a lot more to learn about safety practices when one of their construction laborers was buried beneath collapsing soil during a trench excavation.

On May 4th, 2016, the excavator operator instructed the victim to enter the trench and take grade measurements. The trench lacked proper cave-in protection and the soil shifted on the trench wall. With no time to escape, the victim was buried by the soil.

The Kentucky Fatality Assessment and Control Evaluation Program conducted a formal investigation and found some key facts that were contributing to the incident. They found that the victim’s most recent training was on February 23rd, 2016. This was almost 2.5 months prior to the incident. On the morning of the incident, the employees gathered for a pre-work meeting, which discussed general safety awareness, but did not address proper trench safety or trench hazards.

Other key facts include:

  • lack of proper soil testing of the construction area before excavation
  • lack of prior inspection of the overall workplace
  • lack of safety tools such as a trench box or shoring supports, which were not available on site

Lack of Trench Protective System

OSHA requires sloping, shoring, or use of shields for trenches 5 feet or more in depth. The soil should have been classified as class C. Class C soil requires sloping at 34 degrees.

The trench was too close to the concrete wall making it impossible to create the trench slope on both sides. If this was the case, a trench box or shoring system should have been set up to allow safe entry.

The excavator expected to bench the road-facing side of the trench. OSHA requires that type C soil is sloped and never benched.

The following may have been main contributing factors to the fatality:

  • soil classification
  • lack of trench protective support
  • ladders for trench egress and ingress
  • company safety policies, procedures not enforced
  • not addressing trench safety in the pre-work meeting

Recommendations

During a trench excavation, you may use different methods for grade measurements without the need to enter the trench. It is also important to ensure employees are safe by using adequate protection systems.

While on the excavation site, require a competent person to test the soil and conduct safety inspections daily. It is also necessary to talk about these related safety topics prior to beginning work on the job site. Proper means of ingress and egress should also be provided in all excavations.

As an employer, manager, supervisor, or employee, if you witness unsafe acts on the job site, speak up and intervene. A serious injury can effect lives, think about your workplace, are safety measures put in place to protect you?

For more on this report, please view the Kentucky Injury Prevention and Research Center PDF through this link: http://www.mc.uky.edu/kiprc/face/reports/pdf/16KY017.pdf.

If you would like more information on this topic, please visit OSHAcademy’s free online course: 802 Trench and Excavation Safety.