03 Aug Excavations Are Serious Business

Excavations Are Serious Business

Excavations and trenches do not have to be extremely deep or large to create life-threatening hazards. Soil is heavy, and a cave-in can occur suddenly with little or no warning. Once soil begins moving, there may be no time to escape.

Every excavation is different. Soil type, moisture, depth, excavation configuration, nearby structures, water, vibration, equipment, and spoil piles can all affect stability. Never assume an excavation is safe simply because another excavation at the site appeared similar.

Follow the Competent Person

A competent person must inspect the excavation and has authority to identify hazards and take prompt corrective action.

Follow the competent person’s instructions concerning:

• Soil conditions and classification.
• Sloping, benching, shoring, and shielding.
• Water accumulation and changing conditions.
• Safe access and egress.
• Equipment and spoil-pile placement.
• Hazardous atmospheres when applicable.
• Conditions requiring employees to leave the excavation.

If the competent person identifies evidence of a possible cave-in, protective-system failure, hazardous atmosphere, or other dangerous condition, employees must leave the hazardous area until appropriate corrective action has been taken.

Protect Against Cave-Ins

Employees in excavations 5 feet or more deep generally must be protected from cave-ins unless the excavation is made entirely in stable rock.

Excavations less than 5 feet deep also require protection when a competent person determines there is an indication of a potential cave-in.

Protection may include:

• Sloping the sides of the excavation.
• Benching, where permitted.
• Shoring the excavation walls.
• Shielding, such as an appropriately designed trench box.

Protective systems must be appropriate for the soil, excavation depth, anticipated loads, and site conditions.

When trench boxes or shields are used, employees must remain within the protected area. The box must be installed and used according to applicable OSHA requirements, manufacturer’s tabulated data, or an approved design. Do not assume that every trench box must extend 18 inches above the excavation—the requirement depends on the relationship between the shield, excavation face, and surrounding conditions.

Keep Spoil Piles Back

Excavated soil and other materials can increase pressure on excavation walls and create falling-material hazards.

Keep spoil piles, materials, and equipment at least 2 feet from the excavation edge, or use retaining devices or another effective means to prevent material from falling or rolling into the excavation.

Also consider the weight and vibration produced by vehicles and heavy equipment operating near the excavation.

Provide Safe Access and Egress

In trench excavations 4 feet or more deep, provide a stairway, ladder, ramp, or other safe means of egress.

Access must be positioned so employees do not have to travel more than 25 feet laterally to reach a means of egress.

Before entering:

• Inspect the ladder or other access equipment.
• Make sure it is properly positioned and secured.
• Keep access routes unobstructed.
• Never climb on shoring, trench boxes, utility lines, or equipment as a substitute for proper access.

Watch for Changing Conditions

Conditions can change throughout the workday. Be alert for:

• Cracks or fissures near the excavation.
• Soil sloughing or falling from the walls.
• Bulging or movement at the bottom.
• Water entering or accumulating in the excavation.
• Movement or damage to shoring or shields.
• Increased vibration from nearby equipment or traffic.
• Materials or equipment being placed too close to the edge.
• Changes following rain or other weather events.

A competent person must inspect excavations daily before work begins, as needed throughout the shift, and after rainstorms or other events that could increase hazards.

Protect Employees Around the Excavation

Employees working at the surface can also be exposed to hazards. Appropriate controls may be necessary to protect against falls, mobile equipment, falling materials, and other hazards.

Do not automatically assume that every excavation deeper than 6 feet requires guardrails around its entire perimeter. OSHA fall-protection requirements depend on factors such as whether the excavation is readily visible, whether employees are working near its edge, and whether walkways cross the excavation.

Where fall hazards exist, use the protective measures required for the specific conditions.

Before You Enter

You are the person entering the excavation, so look at the conditions before climbing down.

Ask yourself:

• Has the competent person inspected the excavation?
• Is the required protective system in place?
• Does the protective system appear damaged or disturbed?
• Is safe access available within 25 feet?
• Are spoil piles and equipment far enough from the edge?
• Is water accumulating?
• Are nearby vehicles or equipment creating hazards?
• Have underground utilities been identified and protected?
• Could a hazardous atmosphere be present?

If something does not look right, do not enter. Notify your supervisor or competent person and have the condition evaluated.

Remember

A trench can collapse in seconds. Experience, appearance, and the fact that “we’ve done it this way before” are not substitutes for proper protection.

Inspect it. Protect it. Provide safe access. If conditions are unsafe, stay out. Excavations are serious business.