Trenching & Excavation
Following the tragic deaths of three workers in trench cave-ins, DOSH has dramatically increased trench-related inspections in 2023. One cubic yard of soil can weigh as much as a car. Trench cave-ins pose the greatest risk to workers and are more likely than other excavation-related incidents to result in fatalities.
Other hazards like:
- Drowning (water from rain or busted water pipe(s);
- Electrical shock (unseen buried electrical lines); and
- Carbon monoxide poisoning (exhaust fumes),
can also present serious risks to workers.
This page provides safety and health resource information for employers, supervisors, and workers to keep everyone safe and working.
Since eliminating all hazards on a trenching/excavation site isn’t feasible, changing what’s used and how work is done on a site can prevent injuries and fatalities.
Using a protective system (shields) is the most important method for reducing the risks of cave-ins. Make sure shields are designed by a registered professional engineer and are in good condition prior to use.
Other preventive methods such as:
- Having a competent person to classify soil and rock deposits as type A, B, or C;
- Sloping and benching the sides of the excavation;
Can ensure workers can go home safe to their families.
Learn what you and your workers can do to avoid these types of hazards.
Excavation, Trenching, and Shoring, WAC 296-155 Part N applies to all open excavations made in the earth's surface. Excavations are defined to include trenches formed by earth removal.
Requirements in the rule include:
- Removing or supporting surface hazards and obstacles that are located;
- Identifying and controlling underground installations such as communication lines, sewers, etc.;
- Specifications for entry and exit;
- Protecting workers from vehicular traffic, cave-ins, loose rock or soil, hazardous water accumulation, falls into trenches, and falling loads;
- Warning systems for mobile equipment;
- Hazardous atmospheres: testing, control and rescue operations;
- Stability of adjacent structures;
- Inspections by competent persons;
- Protective equipment and shield specifications;
L&I is conducting rulemaking to update the requirements for trenching & excavating contained in Chapter 296-155, WAC.
See all the rulemaking activity for Trenching Rescue & Excavation on our L&I Rulemaking page
Trenching & Excavation Operations WAC 296-155 Part N. This rule refers to fall protection and how it pertains to excavating and trenching
L&I’s safety and health consultants can help you understand if this rule applies to you and how to implement it.
- Excavation Operations DOSH Directive 27.30
Use these resources and trainings to comply with the Trenching and Excavation Standard.
See the L&I Safety & Health Video Library page for more information on how to borrow DVDs and view videos online.
Videos to watch online
- Excavations in Construction/Trenching Dept. of Labor (DOL)
- Excavations in Construction/Soil Classification (DOL)
Videos to borrow from L&I
- Cave-In! Trenching & Shoring Safety / ¡Derrumbes! Seguridad al zanjar y apuntalar
- In the Trenches : Excavation Safety for Workers
- Trench Box Installation / La instalación de las cibras en las zanjas
Publications, Handouts, Checklists
- An Unprotected Trench is an Early Grave
- Competent Person Evaluation - Excavation & Trenching (F417-104-000)
- Construction Checklist / Español
- Contractor and Laborer Buried in Trench Collapse
- Contractor and Laborer Buried in Trench Collapse Slideshow
- Excavation Trenching and Shoring for OSS - Part 1
- Excavation Trenching and Shoring for OSS - Part 2
- Laborer Partially Buried when Trench Wall Collapses
- Spotter Pinned between Excavator Bucket and Trench Box
- Trenching and Excavation Training Handbook
- Trenching By the Numbers
- Trenching Safety: Preventing Cave-ins (F417-284-000)
Every year in June, the National Utility Contractors Association (NUCA) leads a National Trench Safety Stand-Down as part of Trench Safety Month.
The Trench Safety Stand Down focuses on trench & excavation hazards by reinforcing the importance of using trench protective systems and protecting workers from trenching hazards. Employers encouraged to participate in this safety stand down by taking a break to have a toolbox talk or another safety activity to draw attention to the specific hazards related to working in and around trenches/excavations.
Join us for Trench Safety Stand-Down Week, June 19-23, 2023
Eliminate hazards by conducting a job hazard analysis, updating your required written Accident Prevention Program, and providing required training to ensure all workers are trained on specific job and site hazards.
Complete and review the Construction Safety Checklist, Trenches and Excavations section.
Subscribe to our email list to receive daily resources and reminders during campaign.
Remember to Call Before you Dig before starting any trenching and excavation projects.