Water Hazards in Excavations: Prevention and Protection
The Problem
Water in excavations can quickly turn a routine job into a high-risk situation. Whether it’s causing soil saturation and collapse, eroding trench walls, or creating drowning hazards, water poses serious threats. Ignoring these hazards can lead to serious injuries or fatalities. Today, we’ll look at how water affects excavations, what Canadian safety regulations require, and how we can manage these risks effectively.
Identify the Hazards
- Soil Saturation: Water fills soil voids, making the soil heavier and more slippery, which increases the risk of trench wall failure.
- Erosion: Running or pooling water can undermine the base of the excavation, weakening its structural stability.
- Softened Soil: Prolonged exposure to water softens the soil, making it more likely to collapse under pressure.
- Drowning Hazard: Sudden water accumulation—such as from a broken water main or heavy rainfall—can fill the excavation quickly, posing a serious drowning risk.
Safety Practices and Preventative Measures
Never enter an excavation with standing or incoming water until it has been inspected and cleared by a competent person.
A competent person must assess water-related hazards and determine the required control measures before entry is permitted.
Use pumps or similar equipment to remove standing water. No work should proceed until the excavation is fully drained and deemed safe.
Use shoring or trench shields to stabilise excavation walls, particularly when the ground is saturated with water.
If there is a drowning risk, workers may be required to wear PFDs and lifelines, as assessed and directed by the competent person.
- Alert the competent person: Immediately report any signs of water ingress or accumulation.
- Stay out: Do not enter any excavation containing water until it has been inspected and cleared.
Real-Life Case or Scenario
A crew noticed water pooling in an excavation but continued working without notifying the competent person. Hours later, the trench walls collapsed due to soil saturation, trapping a worker and prompting a full-scale rescue. This incident could have been avoided with proper water removal and a safety evaluation beforehand.
Employee Responsibilities
- Watch for signs of water in or near excavations.
- Immediately report any water accumulation to the competent person.
- Follow all instructions—never enter an excavation without clearance.
- Wear PPE such as personal flotation devices (PFDs) if instructed to do so.
Employer Responsibilities
- Ensure a competent person evaluates any excavation where water is present.
- Provide appropriate pumping equipment and trench protection systems (e.g., trench shields or shoring).
- Train workers to recognise water-related hazards and understand their role in reporting and responding to them.
Discussion & Questions
- “Has anyone experienced water-related hazards in or around excavations? What was the outcome?”
- “What more can we do on this site to prevent or control water hazards effectively?”
Encourage workers to share experiences and ask questions.
Commitment/Action Plan
Let’s commit to staying alert for water hazards and always notifying the competent person. Starting today, if you see any sign of water, don’t ignore it—report it. We will not enter water-filled excavations without proper clearance. Safety comes first.
Wrap-Up
Water may look harmless, but in an excavation, it becomes a serious risk. By recognising the signs, following the correct procedures, and deferring to the competent person’s judgement, we can prevent incidents and keep the job on track. Thank you for prioritising safety on site.
Standards Overview
- Excavation work is risk assessed and monitored by a competent person in accordance with provincial regulations.
- Water-related hazards such as pooling, erosion, or soil saturation are identified and controlled.
- Workers are trained to understand the risks associated with water in excavations and to respond appropriately.
- Refer to CCOHS and your provincial health and safety authority for guidance on excavation safety, managing risks, and working around water hazards.
Disclaimer
“The information provided in this toolbox talk is intended for informational and educational purposes only. It is not a substitute for professional legal, safety, or regulatory advice. The content reflects general best practices and industry standards but may not be applicable to all workplace environments or jurisdictions.
It is the responsibility of employers, supervisors, and workers to ensure compliance with applicable federal, provincial, and territorial laws, regulations, and standards, including but not limited to those set by the Canadian Centre for Occupational Health and Safety (CCOHS) and relevant provincial occupational health and safety authorities. Site App Pro, its affiliates, agents, or representatives—as well as the authors, presenters, and distributors of this toolbox talk—assume no liability for the use or application of the information provided.
Participants are strongly encouraged to consult appropriate legal, safety, or regulatory professionals regarding specific workplace concerns or questions. Always adhere to your organisation’s policies and procedures for health and safety and hazard management.
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