The snow's finally going and the site turns to soup. Ground that held all winter softens fast, and a trench wall that looked solid yesterday can let go today. Thaw is prime season for cave-ins and for machines sinking where they've parked all month.
The hazard
Melting snow and frost coming out of the ground soak the soil. Saturated dirt loses strength, so excavation walls slump and collapse. Soft ground stops carrying the weight it did, and machines tip or sink. Standing water hides holes, edges, and everything you'd otherwise step around. The catch is that nothing about the site looks different from a distance — the change is in ground you can't see.
What to do
- Nobody goes back into an excavation until a competent person has examined it and confirms it is safe. Thaw and rain change the soil, and the soil is what the protection was chosen for. If the protection no longer matches the ground, the excavation is closed until it does.
- Re-check the soil type, don't assume last month's assessment is still valid. Wet, softened, or previously disturbed ground classifies worse, and worse soil needs a flatter slope or a support system.
- Keep the protection right: a compliant support system, or walls sloped to the gradient that soil type requires. Keep one metre at the top edge clear of spoil, rock, material, and equipment.
- Equipment setup is planned, not improvised. Where the ground won't carry a machine, the mats, plates, or pads have to be specified for that load by someone competent to say so — laying whatever plate is on site under a tracked machine is how you get a tip-over. Keep machines back far enough that they can't work an edge loose.
- Dewatering is planned too. Get water out in a way that doesn't undermine the walls or the ground beside and above them, think about where the discharge goes, and check what services are down there before you trench for it. Then have the excavation re-assessed before entry.
- Walk known routes and probe before stepping into deep mud or standing water.
- Waterproof boots with real tread, and knock the mud off ladders, steps, and walkways — the mud you carry up is what you slip on coming down.
Watch out for
- Cracks, slumping, or bulging walls, and spoil sliding back toward the edge.
- A machine leaning, sinking, or its tracks pulling up ground near an edge.
- Water hiding a drop-off, an open hole, or a buried hazard.
- Yesterday's inspection being treated as today's.
Talk it over
- Which spots on this site change the most when they thaw, and who re-examines them before anyone's in there?
- Where are we putting machines this week, and has anyone checked that ground will still carry them?
Fall 2026 · GTA & Hamilton
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