Highlights

Although Rio Tinto never operated Holden, it assumed responsibility for the disused copper mine through acquisition

With a huge remediation project finally completed, Holden stands as an exemplar of what's possible when the mining stops

The project – with its many workers, heavy equipment and infrastructure – also had to take place amidst an established village community

The Holden mine was one of the largest operating copper mines in the US, producing over 90,000 tonnes of copper and by-product metals through its life. When the mine closed in 1957, its tunnels extended for 100km and 7.6 million tonnes of tailings were left on nearby US National Forest land.

Although Rio Tinto never operated Holden, it assumed responsibility for the disused copper mine through acquisition. In the mid-1990s, the US Environmental Protection Agency (EPA) identified a company that was a successor to the mine's operator – and was then owned by aluminium producer Alcan – as responsible for the clean-up at Holden.

In 2007, Rio Tinto acquired Alcan, and stepped up to take responsibility for the Holden reclamation – demonstrating its commitment to what is known as "legacy management".

Describing what happened when the Holden copper mine in Washington State closed in 1957, Dave Cline, general manager, Legacy Management at Rio Tinto notes that: "As was common at the time, the operators just shut down the mine, and walked away from the site."

Sixty years later, with a huge remediation project finally completed, Holden stands as an exemplar of what's possible when the mining stops.

It's an extraordinary story of complex logistics, community engagement and technical expertise. When the hundreds of thousands of trees and shrubs planted on the site are fully grown, the only evidence that this was once a sprawling mine will be a water treatment plant. As Mario Isaias-Vera of the US Forest Service says: "In 20, 30, 40 years I'm hoping to see this area restored, to see wildlife coming back and bears fishing in Railroad Creek."

Dave Cline runs through what's involved in closing the Holden mine

What happens when an operator walks away

Getting from 1957 to the present-day state of the Holden site has been a long, arduous journey. To get a sense of why, consider what happens when an operator just "walks away".

First, the jobs go, affecting not only those directly employed at the mine but also the many other jobs and the communities that depend on them.

Then, there's the environmental legacy. At Holden, for example, acidic water with heavy metals leached from the mine and through tailings piles (waste from the operation), contaminating Railroad Creek, which flows into the 65-kilometre-long Lake Chelan. And the tailings themselves, dumped in steep, unstable piles, presented a further hazard.

Combine this with decaying infrastructure, and what's left is a site that has the potential to be both a social and environmental problem for many years.

 


Life after operation

Every mine has a finite lifespan. Planning for closure and legacy management helps to address the social and environmental consequences when a site shuts down. When Rio Tinto's Lynemouth aluminium smelter in north-east England stopped production, the closure plan helped ensure that most of the skilled workforce were re-employed with local businesses, and the site itself became home to a wide range of businesses producing everything from pre-cast concrete to confectionery.

Working within a remote community

Holden presented particular challenges to the clean-up project. Not least was access. Because of its northerly location in Washington State and its 983-metre altitude, snow means that the mine site is only accessible for six to seven months of the year. Even then, it's a 65-kilometre boat journey up Lake Chelan and 15 kilometres on a gravel road before anyone heading to Holden finally gets there. But remoteness was only part of the challenge. The project – with its many workers, heavy equipment and infrastructure – also had to take place amidst an established village community.

Not long after the closure in 1957, the Holden site was taken over by the Lutheran Bible Institute, which gradually transformed the former mining town at Holden into a religious retreat, described as "a vibrant place of education, programming, and worship". Up to 100 people live year-round at the remote site, welcoming around 5,000 visitors over each summer.

During the five-year remediation project, rather than vacating the site, the community chose to stay and get involved, closing Holden to visitors and instead renting out accommodation to Rio Tinto’s contractors and employees.

"We were living with our local community partners as opposed to next door to them, which was unique," says Dave Cline.

It's been a huge challenge for us to answer to many different parties and make sure they are all satisfied with the work we are doing, that we are complying with the law as well as fulfilling Rio Tinto’s standards for working effectively with communities.

Dave Cline, general manager, Legacy Management at Rio Tinto

Balancing act

So the clean-up project became much more than just an engineering task. It meant balancing the strict requirements of the US Forest Service and the US Environmental Protection agency with the needs of the Holden community and other stakeholders such as the Yakama Nation and the Washington Department of Ecology.

As Dave Cline admits, "It's been a huge challenge for us to answer to many different parties and make sure they are all satisfied with the work we are doing, that we are complying with the law as well as fulfilling Rio Tinto's standards for working effectively with communities."

Despite these challenges – and a two-month interruption in 2015 by the first major wildfire in the area for over 100 years – the remediation project went ahead on schedule.

Surviving wildfire

In 2015, lightning sparked a wildfire that went on to engulf more than 280km² of wilderness around the Holden site. The fact that the village survived the destructive "Wolverine Fire" intact was seen by some as little short of miraculous. Land cleared around Holden helped to buffer the village from the fire. But it was a combination of controlled burning and community effort – coupled with the fact that the fire started just after powerful sprinklers had been installed as part of the remediation programme – that saved the village from the flames.

335

metres of Railroad Creek realigned

Engineering challenge

Earthmoving and construction projects on a huge scale were needed to make sure the old mine would no longer pollute the surrounding wilderness. Engineers plugged the tunnel openings, inserting valves that piped water to a plant where it is treated to water quality standards before being released back into Railroad Creek. The plant will run for decades to come. To stop water from the tailings piles leaching into the creek, engineers built a 1.6-kilometre-long concrete barrier wall that extends up to 30 metres underground to collect the groundwater, so it too can be treated at the plant.

The tailings piles themselves were regraded from an unstable 1:1 ratio (with steep 45-degree slopes), to much more stable 3:1 slopes. And to stop the piles from failing even under a maximum credible earthquake scenario, cement grout was injected into the underlying foundations. Finally, 335 metres of Railroad Creek were rerouted around contaminated areas, creating habitat suitable for fish to return to these sections of the stream.

Native shrubs and trees are now being planted on top of the waste rock and tailings piles so that over time, what was once visible from the air as a huge scar on the land will eventually blend in with the wilderness that surrounds it.

Holden milestones

1896 - First ore discovered by prospector James Henry Holden

1938 - Howe Sound Mining Co. delivers first shipment of ore concentrate

1957 - Holden copper mine closed

1958 - Lutheran Bible Institute acquires Holden village

2007 - Rio Tinto inherits mine site as part of Alcan acquisition

2011 - Remediation begins

2015 - Wildfire, first in 100 years, interrupts project

2017 - Remediation and revegetation completed; summer visitors return to Holden Village for the first time since 2012

For closure, planning is key

It's taken five years and US$500 million to remediate Holden. In fact, the costs have been estimated to exceed the income that Holden generated for its original operators the Howe Sound Mining Company. Matthew Bateson, Rio Tinto's head of Environment & Legacy Management, says: "The closure of old sites can be more complex and costly than the industry has internalised. It's an issue that all mining companies have to face. Many mines opened and operated at a time when regulations were lighter, and practices different. As more mines approach the end of their lives, closure is going to become a bigger issue for the industry."

Matthew points out that while the remediation requirements for Holden are exceptionally strict, regulations and practices around the world mean closure is becoming generally more complex and expensive. In today's environment, planning is key to controlling costs and getting successful outcomes, says Matthew.

"Ignoring closure issues during operations stores up problems for the future. If, on the other hand, sites plan actively for it – for example being clear about what the final closure landforms will look like – this will both reduce future costs and make them more predictable." Rio Tinto's acquisitions mean the company has a significant portfolio of legacy sites to manage, providing a learning platform for when the company has to close its own operations. Matthew cites Rio Tinto's Diavik operation in Canada's Northwest Territories as an example of a site that puts knowledge like this into practice: "Diavik has planned for closure from the outset, so the costs and scope have been well understood and remained more consistent over the life of the mine."

An important lesson from Holden, according to Matthew, is that the skillset of a mining company makes it well suited to manage a large-scale closure project: "In essence, we have had to blend regulatory and partnership skills and delivery of environmental and social objectives with an engineering project management mind-set. And we're proud of what's been achieved at Holden: there are few examples of success on this scale in the mining industry."

US $240m

contributed to the local economy

Secure future

While the process has been an enormous challenge, it's brought many benefits to the area. The remediation project contributed around US$240 million to the economies of Chelan and Douglas counties, as people and equipment were sourced locally. It has also removed a source of long-term pollution from the environment. Up to eight people will be permanently employed operating the water treatment plant, and a full-time Rio Tinto employee will manage the remediated site from a base in Chelan.

And as Dave Cline concludes, it has secured the future of an important community: "It's turned out to be a very positive relationship between Holden Village and Rio Tinto. And while it's been hard for us to rehabilitate this legacy that was left by the Howe Sound Mining Company, we’re both very focused on what the end game is: re-establishing this area into its natural habitat and beauty, so the community can continue their existence in the next 50 years and beyond in a place that's been healed by the remediation process."