Digging deeper: Excavation and trenching safety

Excavation and trenching activities are among the most dangerous tasks in construction. Between 2011 and 2016, there were 130 fatalities recorded in excavation and trenching operations. Cave-ins pose the greatest risk and are much more likely than other excavation-related accidents to result in worker fatalities. One cubic yard of soil can weigh as much as a car! Employers must ensure that workers enter trenches only after adequate protections are in place to address cave-in hazards.

Other potential hazards include falls, falling loads, hazardous atmospheres, and incidents involving mobile equipment.

The importance of preplanning

Before starting work, employers planning an excavation must:

• Determine the approximate location of utility installations — sewer, telephone, fuel, electric, and water lines, or any other underground installations.
• Contact the utility companies or owners involved to inform them of the proposed work within established or customary local response times.
• Ask the utility companies or owners to find the exact location of underground installations. If they can’t respond within 24 hours (unless the period required by state or local law is longer) or can’t find the exact location of the utility installations, the excavation may proceed with caution.

If excavation work exposes underground installations, OSHA regulations require these installations to be protected, properly supported, or removed.

Keeping workers safe

One of the most important ways to ensure workers in excavations are safe is to use protective systems, which are designed to protect workers by preventing trench walls from collapsing. All excavations in which workers could potentially be exposed to cave-ins must be protected by one of the following methods:

• Sloping or benching the sides of the excavation, or
• Supporting the sides of the excavation by placing a shield between the side of the excavation and the work area.

Other requirements include:

• Keep heavy equipment from trench edges.
• Keep surcharge loads(spoil, other materials to be used in the trench) at least 2 feet from trench edges.
• Know where underground utilities are located.
• Test for low oxygen, hazardous fumes, and toxic gases.
• Inspect excavations at the start of each shift.
• Inspect excavations following a rainstorm.
• Don’t work under raised loads.

Emergency rescue equipment

Emergency rescue equipment is required by OSHA when a hazardous atmosphere exists or may reasonably be expected to develop during excavation work. However, OSHA recommends that companies have emergency response procedures in place, and rescue equipment ready, in case any accident occurs. Ensure the procedure includes:

• Who will provide immediate jobsite rescue and aid;
• Who will notify the authorities and rescue personnel;
• Who will meet, advise, and direct rescue personnel; and

What emergency response equipment will be available on the jobsite, where it will be kept, and who will be trained to use it.