Diavik: End of a Diamond Era

It's the end of an era for Canada's Diavik diamond mine - and the start of a huge project to restore the land to its natural state.

Commercial production comes to an end this month after 23 years. Regulators in Northwest Territories (NWT) officially approved a final closure and reclamation plan earlier this week.

The site - an island in the middle of a frozen lake, where winter temperatures fall to -40C/-40F - will be transformed over the next three years.

Future generations will see virtually no signs of its previous life, as Canada's biggest producing diamond mine (150m carats in total).

But it is a vast undertaking. The cost of closing a diamond site often rivals the cost of opening it. The Initial construction costs at Diavik, at Lac de Gras, was around CAD 1.28bn, or USD 850m at historic exchange rates.

Owners Rio Tinto has to dismantle processing plants, crushers, the camps that housed 700 workers, the four huge wind turbines that powered the mine and the 1,600m gravel airstrip - big enough to handle a Boeing 737 - that has been used primarily to fly employees in and out.

Fuel farms that held millions of litres of diesel also have to be demolished, hazardous chemicals, batteries, and asbestos have to be removed, either by air, or by the ice road that operates across frozen lakes in the coldest months of the year.

The four open pits where mining at Diavik took place until 2012, will be gradually flooded with water from Lac de Gras over an eight-month period.

Millions of tonnes of tailings - the leftover mud from crushing diamond ore - must be frozen and safely buried or submerged to prevent quicksand traps for wildlife, water pollution, and erosion risks.

Gravel pads, roads, and waste piles will be removed, spread with topsoil and planted with fireweed, willows, blueberries, grasses and other native species to restore the site to how it used to be.

All of this, and much more besides, will restore Lac de Gras to its original state.

And bring back the herd of around 6,000 caribou that swim to the island on their epic 3,000-mile annual migrations. They currently avoid the mine area because of the noise, lights, dust, and roads.

Water quality will be strictly monitored to encourage trout, cisco and other cold-water fish to spawn.

Diavik is the first NWT diamond mine to undergo a "scheduled closure". Other mines in the territory have closed - Giant and Cantung ceased operations abruptly because of financial woes, and remained on care and maintenance for many years. But Diavik is a planned and managed affair.

Diamonds were first discovered at Diavik in summer 1994 by Aber Diamond Corporation. It later became Harry Winston Diamond Corporation and then Dominion Diamond Mines.

Rio Tinto, now the 100% owner, formed a joint venture (60% ownership) with Aber in 1998.

Canada was just at the start of its diamond journey when diamonds were found at Diavik. Three years earlier in November 1991, the country's first diamond deposits were discovered at what became the Ekati mine, also in NWT.

The closure of Diavik leaves two diamond mines operating in NWT. Ekati, owned by Australian miner Burgundy, dodged bankruptcy last December, thanks to a CAD 115m (USD 83.5m) loan from Canada's federal finance department, which could feasibly extend its life to 2040.

Gahcho Kue, jointly owned by De Beers and Mountain Province, has paused plans for an expansion that would have extended its life to 2031 or beyond, citing unfavorable market conditions. It is unlikely to continue operating beyond 2026 or early 2027.

Have a fabulous weekend.