Giant Mine Shows Why Remediation Contractors Need More Than a CGL

Ottawa has now spent more than $1.5 billion cleaning up Giant Mine, the former gold mine inside Yellowknife's city limits, and the approved budget sits at $4.38 billion through 2038. Most of that money flows to contractors: demolition crews, earthworks firms, drillers installing freeze systems, haulers, water treatment builders and the consultants who design and monitor the work.

Every one of those firms works on a site where the contamination is known, mapped and extreme. A contractor at Giant Mine cannot be surprised by arsenic. Its exposure is making a known condition worse, and that is the exposure a standard CGL is written to exclude.

What is happening at Giant Mine

Giant Mine operated from 1948 to 2004. Roasting arsenopyrite ore to free the gold produced arsenic trioxide dust, and about 237,000 tonnes of it remain stored underground. Canada took responsibility for the site when Royal Oak Mines went bankrupt in 1999. Crown-Indigenous Relations and Northern Affairs Canada now runs the remediation under Type A Water Licence MV2007L8-0031, issued in September 2020 and valid to 2040.

The chosen method freezes the arsenic trioxide in place. Thermosyphons installed around the underground chambers keep the rock frozen so water cannot reach the dust and carry it off. This year the project is deconstructing the mill, the tailings reprocessing plant and the C-Dry building, with about 30 smaller structures due to come down in 2027. The new water treatment plant was 80 per cent built this spring and should be fully running in 2027, and the thermosyphon drilling contract for the AR1 freeze pad was due for award in early summer.

Parsons is the Main Construction Manager, acting as mine manager and prime contractor, and it tenders most work packages through MERX. Environment Journal reported another of its notices of contracting opportunity, for 2027 work, in early November. The schedule was stretched by nine years partly to build northern bidding capacity, so many packages are sized for smaller northern firms, Indigenous-owned businesses and joint ventures.

Giant Mine is Canada's most expensive remediation project, and the same contractor exposure repeats on federal sites across the country. The Federal Contaminated Sites Action Plan runs to 2034, with $1.48 billion committed for Phase V from 2025 to 2030 for airports, bases, harbours and northern sites.

How a release reaches the contractor

Scenario. This is a hypothetical. A demolition subcontractor is taking down a mill building in July. Dust controls are in place inside the wrapped structure, but a crew stages arsenic-bearing debris outside ahead of a crane lift, and an overnight wind event carries fine material toward a neighbouring property and the shoreline. Sampling the following week shows arsenic above background on the neighbour's land and in nearshore sediment.

Mechanism. The prime contractor directs the cleanup and tenders the cost to the subcontractor under the indemnity in its subcontract. The neighbour claims property damage and loss of use, and the regulator wants the off-site impact delineated and removed. The subcontractor reports to its CGL, where the pollution exclusion removes injury and damage arising from the release of pollutants. The limited exceptions in most Canadian forms deal with things like heating equipment and hostile fire, and none of them reach demolition dust.

Canadian appellate courts have enforced that exclusion where the insured's own operations carried a known pollution risk. In ING Insurance Company of Canada v. Miracle, 2011 ONCA 321, the Ontario Court of Appeal applied it to gasoline escaping from a service station tank and confined the "active industrial polluter" language from Zurich v. 686234 Ontario to the facts of that case. In Precision Plating v. Axa Pacific, 2015 BCCA 277, the B.C. Court of Appeal held that "caused by, contributing to or arising out of" wording excluded chemical damage to neighbours even though a fire started the loss, and the Supreme Court of Canada refused leave in 2016. A contractor disturbing arsenic waste has very little room to argue around that reasoning.

Outcome. The claim lands on the Contractors Pollution Liability (CPL) policy, and the wording decides the result. A CPL with an affirmative grant for disturbance or exacerbation of pre-existing conditions responds to the off-site cleanup, the neighbour's claim and the defence. A CPL that excludes known or pre-existing conditions leaves the contractor paying to recover arsenic it did not put there, because every gram it released was already on site.

Where contractor programs fall short

CPL on public remediation work is usually bought to satisfy a certificate. The tender asks for CPL, a limit and additional insured status, and the placement matches the certificate without anyone testing what the form does on a site like this one. Four wording points decide whether the policy is worth its premium.

Exacerbation. Look for an affirmative grant covering disturbance or aggravation of pre-existing pollution conditions, and check that no known-conditions or prior-pollution exclusion takes it back. On a legacy mine site this is the whole policy.

Tail. Active remediation at Giant runs into the late 2030s, followed by perpetual care, with Ottawa estimating about $10 million a year for post-remediation operation and maintenance. A driller that installs thermosyphons in 2027 has a completed operations exposure if part of the freeze system fails a decade later. Claims-made CPL with a short extended reporting period fits that profile poorly. Occurrence wording, or a project-specific policy with a matching completed operations period, fits it far better.

Professional work. Packages such as the water treatment plant, freeze design and the perpetual care plan carry design and advice exposure. A contractor that designs what it builds needs contractors professional cover that includes pollution, and consultants on these sites need Environmental E&O that responds when their advice leads to a release.

Joint ventures. The Giant Mine Oversight Board has raised concerns about joint ventures competing for packages meant for Indigenous-designated firms. Whatever view one takes of the procurement question, the insurance point is simpler. Most liability forms exclude joint ventures that are not shown in the declarations, so a JV formed for one bid may hold a certificate and no pollution cover.

Underwriters pricing this work want the contaminant profile, the scope of disturbance, the dust and water controls, and where removed material goes. Contractors that bring that to the submission get exacerbation cover at a sensible price. Contractors that bring only a certificate request often end up with a form built to exclude the very exposure they are bidding on.

What brokers should do now

• Demolition and earthworks contractors bidding remediation tenders: pull the current CPL and confirm the exacerbation grant and the absence of a known-conditions exclusion before the bid goes in.
• Drillers, freeze system and water treatment installers: compare the policy trigger and extended reporting period with the service life of what they are installing, and ask for occurrence or project-specific terms.
• Design-build firms: confirm whether the CPL or a separate professional policy covers pollution arising from design. The gap usually sits between the two.
• Indigenous-owned firms and joint ventures: check that every JV entity is a named insured on the policy the certificate refers to.
• Haulers of contaminated material: confirm transportation pollution and non-owned disposal site coverage for any load that leaves the site.

Giant Mine will keep putting contracts on the street until the late 2030s, and FCSAP funding keeps similar work moving on federal sites from coast to coast. If you place contractors or consultants on this work, send us the CPL or Environmental E&O they carry now and the scope they are bidding, and TerrAssure underwriting will show you where the wording holds and where it does not. Start the conversation here.

Sources

• Cabin Radio: What to expect at the Giant Mine site for the rest of 2026
• Cabin Radio: Giant Mine remediation passes $1.5 billion in spending
• Environment Journal: Giant Mine Remediation Project provides notice of contracting opportunity for 2027
• CBC News: Cost of cleaning up Yellowknife's Giant Mine now pegged at $4.38B
• Global News: Arsenic-contaminated Giant Mine seen as low-risk during N.W.T. fire
• Giant Mine Oversight Board: Water licence status
• Mackenzie Valley Land and Water Board: Reasons for Decision on Motion, MV2007L8-0031
• Government of Canada: Funding of federal contaminated sites
• Mondaq: Ontario Court of Appeal clarifies pollution exclusion clauses (ING v. Miracle)
• Ontario Bar Association: Insurer off the hook for release of pollutants caused by fire (Precision Plating)