Anonymised, illustrative composite. An Alberta excavation contractor struck buried services twice on the same multi-phase site, and the two incidents ended in opposite outcomes for one reason.
At a glance
The dig ran in two phases on the same site. Between them, a permitting delay and a stretch of bad weather pushed the second phase eleven weeks past the first. The crew treated it as one continuous job and did not revisit the paperwork in between.
Alberta’s OHS Code requires more than a one-time site hazard assessment. Under Part 2, s.7(1), an employer must assess the work site and identify hazards “before work begins,” and under s.7(4) must repeat that assessment “at reasonably practicable intervals… when a new work process is introduced, when a work process or operation changes, or before the construction of significant additions or alterations to a work site.” An eleven-week gap spanning a season change is not something s.7(4) lets an employer treat as still current. The Code also names the specific step meant to prevent a strike in the first place, and it sits in a different part entirely from the hazard-assessment rule above: s.447(1.1) covers any pipeline or buried facility owner within 30 metres of the dig, and bars an employer from breaking ground until that owner has been contacted, told what the crew intends to do, and given the chance to mark what is actually underground. That is the locate step Phase 1’s crew had already cleared before the strike, which is the reason it read as unavoidable rather than a compliance gap.
In Phase 1, the hazard assessment was completed days before digging began, correctly logged the locate request for buried gas and electrical service near the trench line, and the crew still struck a service — one that was genuinely absent from the utility’s own mapping, not something a fresh assessment or locate could have caught. The resulting delay cost of $18,200 was billed to the GC as a legitimate site condition and paid in full.
In Phase 2, the same kind of strike occurred, this time after the eleven-week gap with no refreshed assessment on file. Delay cost: $23,400. The GC declined to pay: the excavator’s own hazard-assessment records could not show a reassessment across a gap that spanned a season and a scope change, so the delay was treated as a compliance failure on the excavator’s side rather than an unavoidable site condition. Of $41,600 billed across both phases, $18,200 — 44% — was recovered.
The two strikes were the same kind of event with the same underlying cause — an unmapped buried service — and the outcome still split, because s.7(4)’s reassessment trigger did or did not get honoured. Where the assessment was current, the strike was accepted as something no amount of diligence would have prevented. Where it was not, the gap itself became the reason to refuse payment, independent of whether a refreshed assessment would actually have caught this particular service.
The firm now sets a hard reassessment trigger — any gap of more than two weeks between hazard assessment and mobilization requires a documented refresh, not just a note that the original assessment still applies. See how to write a field-level hazard assessment. A related billing dispute over undocumented extras is in how an electrical sub priced eighty verbal extras, and a related contested back-charge is in how a fit-out firm split a contested back-charge.
Had Phase 2's hazard assessment been refreshed before mobilization the way Phase 1's was, there is no reason on this record to think the second strike would have been treated any differently from the first — a genuinely unmapped service, struck despite a current, properly logged assessment. That would have meant $23,400 more recovered, bringing total recovery to the full $41,600 instead of $18,200: the entire difference between the two outcomes traces to one lapsed reassessment, not to anything about the strikes themselves.
Track elapsed time since the last hazard assessment against s.7(4)'s reassessment triggers — a new work process, a changed operation, or simply enough time passing that "reasonably practicable" clearly requires a refresh — the same way you would track any other compliance deadline with a dollar figure attached to missing it. An eleven-week gap spanning a season change is exactly the kind of interval the Code does not let stand unrefreshed.
The firm's new rule ties reassessment to elapsed time specifically because "the crew feels the site hasn't changed" is not a standard s.7(4) recognizes, and it was exactly the assumption that let an eleven-week gap pass unaddressed the first time. A gap of two weeks or less is treated as still covered by the original assessment; anything longer, or any gap spanning a season change or a scope change regardless of length, triggers a documented refresh before remobilization. The rule costs the firm a short, routine paperwork step on every multi-phase job; the alternative, on this project alone, cost it $23,400 of an otherwise identical delay claim.
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