Excavation Safety Basics: Lessons From NAXSA’s Tips From the Trench
Excavation safety starts with understanding the hazards before anyone enters the trench. NAXSA’s Tips From the Trench provides a practical field reference covering competent-person responsibilities, access and egress, spoil-pile setbacks, protective systems, tabulated data, and pre-job planning.
Quick Guide/Information for Excavations • September 2022
Four Excavation Safety Basics to Remember
Minimum spoil-pile setback identified in the NAXSA guide.
Excavation depth at which a safe means of access and egress is required.
Maximum lateral travel distance to a means of egress identified by NAXSA.
Keep applicable manufacturer tabulated data available for the protective system.
Understand the Excavation Terminology
Clear terminology matters because excavation safety plans, OSHA requirements, manufacturer instructions, and tabulated data all use specific terms.
NAXSA identifies an excavation as a man-made cut, cavity, trench, or depression created by removing earth. A trench is a narrower type of excavation made below the ground surface.
Excavation
A man-made cut, cavity, trench, or depression formed by earth removal.
Shoring
A support system used to help prevent movement of soil, underground utilities, roadways, foundations, and other structures.
Protective System
A broader category that can include support systems, sloping, benching, shields, and other methods of employee protection.
The Competent Person Has a Central Role
One of the most important points in the NAXSA guide is the role of the Competent Person.
NAXSA describes the Competent Person as someone capable of identifying existing and predictable hazards or dangerous working conditions and who has the authority to take corrective action.
That responsibility extends beyond looking at the trench once at the beginning of the day. Excavation conditions can change as work progresses, weather changes, groundwater appears, equipment moves, or soil begins cracking or sloughing.
Changing Conditions Can Change Protective-System Requirements
NAXSA’s pre-job checklist specifically calls attention to changing site conditions, including weather and soil changes.
A protective system that was suitable earlier in a project may need to be reevaluated when excavation conditions change.
For hydraulic shoring, soil classification can affect excavation depth, horizontal shore spacing, cylinder placement, sheeting requirements, and the overall system layout.
Continue learning:
See how soil classification affects hydraulic-shoring selection
and configuration.
Spoil Placement and Safe Access Matter
Keep Spoil Back
The NAXSA quick guide identifies a minimum 2-foot setback for spoil piles from the trench edge. Spoil, materials, equipment, and other nearby loads can increase pressure on the excavation wall.
Plan Safe Access
For excavations more than 4 feet deep, NAXSA notes that workers need an appropriate means of access and egress with no more than 25 feet of lateral travel.
The Protective System Must Match the Excavation
There is no single trench-protection system that is automatically appropriate for every excavation. Depending on the project, protection may involve several different methods.
The appropriate approach depends on factors such as soil conditions, excavation depth and width, groundwater, surcharge loads, nearby structures, the work being performed, and applicable design information.
Shielding or shoring?
Learn how hydraulic shoring and trench boxes protect workers
in different ways.
Manufacturer Tabulated Data Must Be Part of the Job
NAXSA reminds crews that shoring systems must be used in accordance with the applicable manufacturer tabulated data.
Tabulated data establishes the conditions and configurations under which a protective system may be used.
Tabulated Data May Address
A Pre-Job Checklist Helps Catch Problems Early
NAXSA closes its quick guide with a straightforward pre-job checklist. Together, these items create a useful routine before excavation work begins.
Confirm the Competent Person is on site.
Know how many employees are on the jobsite.
Inspect and document site conditions.
Watch for changing weather and soil conditions.
Have a work plan in place.
Confirm the appropriate protective equipment is available.
Make sure applicable tabulated data is on site.
Review applicable OSHA, state, and local requirements.
Excavation Safety Starts Before Entry
The practical lesson from NAXSA’s quick guide is straightforward: trench safety depends on decisions made before workers enter the excavation. Soil evaluation, protective-system selection, equipment configuration, spoil placement, safe access, inspections, applicable tabulated data, and Competent Person oversight all need to be considered before work proceeds.
More Tips From the Trench From NAXSA
NAXSA maintains additional Tips From the Trench resources covering excavation and shoring topics. These short references can be useful for toolbox talks, safety meetings, crew training, and quick field references.
Iron Lot Trench Safety Resources
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Iron Lot supplies trench boxes, hydraulic shoring, manhole boxes, bedding boxes, road plates, and related excavation equipment for contractors, municipalities, utility crews, and public works departments.
Contact Iron Lot →Safety note: This article is intended as a general educational resource and is not a substitute for OSHA regulations, applicable state requirements, manufacturer instructions, tabulated data, engineered designs, or evaluation by the project Competent Person.