Trenching and Excavation Safety

Trench collapses, or cave-ins, pose the greatest risk to workers’ lives. When 

done safely, trenching operations can reduce worker exposure to other potential 

hazards include falls, falling loads, hazardous atmospheres, and incidents 

involving mobile equipment. 

OSHA standards require that employers provide workplaces free of recognized 

hazards. The employer must comply with the trenching and excavation 

requirements of 29 CFR 1926.651 and 1926.652 or comparable OSHA-approved 

state plan requirements.

Trench Safety Measures

Trenches 5 feet (1.5 meters) deep or greater 

require a protective system unless the excavation 

is made entirely in stable rock. If less than 5 feet 

deep, a competent person may determine that a 

protective system is not required. 

Trenches 20 feet (6.1 meters) deep or greater 

require that the protective system be designed 

by a registered professional engineer or be 

based on tabulated data prepared and/or 

approved by a registered professional engineer 

in accordance with 1926.652(b) and (c).

Competent Person

OSHA standards require, before any worker 

entry, that employers have a competent person 

inspect trenches daily and as conditions change 

to ensure elimination of excavation hazards. 

A competent person is an individual who is 

capable of identifying existing and predictable 

hazards or working conditions that are hazardous, 

unsanitary, or dangerous to workers, soil types 

and protective systems required, and who is 

authorized to take prompt corrective measures to 

eliminate these hazards and conditions.

Access and Egress

• Keep heavy equipment away from trench edges.

• Identify other sources that might affect 

trench stability.

• Keep excavated soil (spoils) and other 

materials at least 2 feet (0.6 meters) from 

trench edges.

• Know where underground utilities are located 

before digging.

• Test for atmospheric hazards such as low 

oxygen, hazardous fumes and toxic gases 

when > 4 feet deep.

• Inspect trenches at the start of each shift.

• Inspect trenches following a rainstorm or 

other water intrusion.

• Do not work under suspended or raised loads 

and materials.

• Inspect trenches after any occurrence that 

could have changed conditions in the trench.

• Ensure that personnel wear high visibility or 

other suitable clothing when exposed to 

vehicular traffic.

Protective Systems

There are different types of protective systems.

Benching means a method of protecting workers 

from cave-ins by excavating the sides of an 

excavation to form one or a series of horizontal 

levels or steps, usually with vertical or nearvertical surfaces between levels. Benching 

cannot be done in Type C soil.

Sloping involves cutting back the trench wall at 

an angle inclined away from the excavation. 

Shoring requires installing aluminum hydraulic 

or other types of supports to prevent soil 

movement and cave-ins.

Shielding protects workers by using trench 

boxes or other types of supports to prevent soil 

cave-ins. Designing a protective system can 

be complex because you must consider many 

factors: soil classification, depth of cut, water 

FactSheet
content of soil, changes caused by weather 

or climate, surcharge loads (e.g., spoil, other 

materials to be used in the trench) and other 

operations in the vicinity.

Additional Information

Visit OSHA’s Safety and Health Topics 

webpage on trenching and excavation at 

www.osha.gov/trenching.

Workers’ Rights

Workers have the right to:

• Working conditions that do not pose a risk of 

serious harm.

Receive information and training (in a 

language and vocabulary the worker 

understands) about workplace hazards, 

methods to prevent them, and the OSHA 

standards that apply to their workplace.

• Review records of work-related injuries 

and illnesses.

• File a complaint asking OSHA to inspect their 

workplace if they believe there is a serious 

hazard or that their employer is not following 

OSHA’s rules. OSHA will keep all identities 

confidential.

• Exercise their rights under the law without 

retaliation, including reporting an injury or 

raising health and safety concerns with their 

employer or OSHA. If a worker has been 

retaliated against for using their rights, they 

must file a complaint with OSHA as soon as 

possible, but no later than 30 days.

For additional information, see OSHA’s Workers 

page (www.osha.gov/workers).

How to Contact OSHA

Under the Occupational Safety and Health Act 

of 1970, employers are responsible for providing 

safe and healthful workplaces for their employees. 

OSHA’s role is to help ensure these conditions 

for America’s working men and women by 

setting and enforcing standards, and providing 

training, education and assistance. For more 

information, visit www.osha.gov or call OSHA at 

1-800-321-OSHA (6742), TTY 1-877-889-5627.

DOC FS-3476 09/2011

This is one in a series of informational fact sheets highlighting OSHA programs, policies or 

standards. It does not impose any new compliance requirements. For a comprehensive list of 

compliance requirements of OSHA standards or regulations, refer to Title 29 of the Code of Federal 

Regulations. This information will be made available to sensory-impaired individuals upon request. 

The voice phone is (202) 693-1999; teletypewriter (TTY) number: (877) 889-5627.