Trenching and Excavation Safety

Overview

Working in an unprotected trench is dangerous. The walls can collapse suddenly and without warning. When this happens, workers do not have time to move out of the way.

While a small amount of dirt may not seem dangerous, one square yard of dirt can weigh more than 3,000 pounds. This weighs the same as a compact car. This small amount of dirt is enough to fatally crush and suffocate workers.

Injuries and deaths related to trench collapses continue to happen. From the years 2003 to 2017, there were a total of 373 trenching deaths. More than 80% of those deaths happened in the construction industry. Workers do not often survive trench collapses, but we can prevent them.

Keeping workers safe

There are ways to prevent trench collapses. Engineering controls, protective equipment, and safe work practices can reduce hazards to workers and prevent trench cave-ins.

Workers should never enter a trench that does not have a protective system in place.

A competent person should design and install the protective system. A competent person can find hazards and correct them.

Workers can take training to become a competent person. Training is available from many sources, including:

• insurance companies,
• trade associations,
• labor unions, and
• companies that make safety equipment for trench workers.

Preventing trench collapses

Planning

To prevent trench collapses, employers must plan before the job begins. Employers should:

• Assign and train a competent person.
• Call 811 to identify and mark underground utility lines.
• Dig a minimum of 5 feet away from utility lines.
• Evaluate the soil to determine its stability.
• Plan the job layout to identify safe locations for spoil piles and heavy equipment routes.
• Before the job starts, if the trench will be 5 feet or deeper, set up a protective system.
• If the trench will be 20 feet or deeper, provide engineering protections.
• Have a traffic control plan and lane closure permits.
• Develop a trench emergency action plan.

OSHA Standard

The OSHA standard for excavations, including trenches, is 29 CFR* 1926 Subpart P . This standard de­scribes the precautions needed for safe excavation work. OSHA requires that all excavations 5 feet deep or great­er make use of one of the following pro­tective system options:

• Sloping the ground
• Benching the ground
• Shoring the trench with supports (such as planking or hydraulic jacks)
• Shielding the trench (using a trench box)

Other Methods

The best way to prevent trench collapse and trenching-related deaths is to use other methods when possible. Some other options include:

• directional boring,
• relining the pipe,
• pipe ramming, and
• utility tunneling or pipe jacking.

Robots can be used on construction sites to transport, line, and join large pipes to protect workers from serious injuries. Robots may reduce the need for pipe layers and other helpers to work at the bottom of the trench.

Programs and initiatives

Resources

NIOSH Resources

Trench Safety: Before you did it, plan it! Infographic [en español]

Development of Draft Construction Safety Standards for Excavations

NIOSH Fatality Assessment and Control Evaluation (FACE) Program

The FACE program aims to prevent occupational fatalities across the nation by identifying and investigating work situations at high risk for injury and then formulating prevention strategies to those who can intervene in the workplace.

NIOSH FACE Trenching Reports

State FACE Trenching Reports

NIOSHTIC-2

A searchable bibliographic database of occupational safety and health publications, documents, grant reports, and journal articles supported in whole or in part by NIOSH.

Preventing Deaths and Injuries from Excavation Cave-Ins: NIOSH Alert

Presents four case studies of worker deaths in trench cave-ins, as well as recommended work practices, overview of standards, and more.

Preventing Trenching Fatalities

NIOSH Science Blog that describes the risks construction workers face when working in trenches.

Preventing Worker Deaths from Trench Cave-ins

Information on NIOSH recommended engineering controls, protective equipment, and safe work practices to reduce hazards for workers. [en español]

Trench Safety Awareness Web-based training

A training on conducting a safe trenching operation. Topics include the four types of trench collapse, the frequency and cost of trench collapses, trench soil types, and common trench protective systems.

Trench Cave-ins: NIOSH Update

NIOSH publication that describes worker deaths from trench cave-ins and provides recommendations for prevention.

OSHA Resources

Construction eTool – Trenching and Excavation

National Emphasis Program on Trenching and Excavation

OSHA Standards for Excavation

Trenching and Excavation

Protect Workers in Trenches safety video [en español]

Trenching and Excavation Safety Factsheet

CPWR - Center for Construction Research and Training Resources

No New Year — Trench Collapse [en español]

Practice Trench Safety. It Saves Lives [En Espanol]

Trench Safety – Resources to Promote Safe Work in Trenches —CPWR

Trenches Hazard Alert [en español]

Recent Trenching Fatalities: Causes and Ways to Reduce

Trench Safety Toolbox Talk [en español]

Trench and Excavation Hazards: Insight on Newly Acquired Data and Managing the Risks

Webinars

Increasing Awareness of Factors that Influence Trench Safety

Learn about recent trends and a collaborative effort to increase awareness of the factors that may contribute to trenching incidents and ways to mitigate the risks. Download Presentation Slides

OSHA and American Society of Safety Professionals Share Trenching Safety Webinar:

Learn how contractors and workers can conduct excavation and trenching operations safely by following subparts of 29 CFR 1926, as well as the best practices described in industry consensus standards such as ANSI/ASSP A10.12.