Tailings and earthquakes, Part 1

Posted by Elizabeth Bluemink

Posted: March 24, 2008 - 4:50 pm

Earthquakes are one of the hazards that would be evaulated during the permitting process for a potential mine like Pebble.

Judging from a few e-mails I've received, people are interested in this topic, so I've been working intermittently on a blog post about Pebble and earthquakes.

This morning, an interesting news item arrived by e-mail. The Salt Lake Tribune has published an investigation detailing how former managers of the large open-pit Kennecott copper mine in Utah hid significant seismic risks posed by the mine's tailings impoundment from people who lived nearby. The company's engineering studies showed an earthquake-induced tailings dam failure could bury hundreds of homes in mining waste.

After reviewing the engineering reports, the Kennecott Utah Copper Corp. started a multi-million dollar project to shore up the dam. But in the interim, the mining company didn't offer its findings to the public, didn't offer to relocate anyone, and according to the Tribune, colluded with state regulators to bury the "alarming" engineering reports.

Company documents show Kennecott's president at the time was worried about "panic and suits," according to the Tribune.

Kennecott purchased many of the homes in the at-risk neighborhood, reportedly working with an investment firm to keep the nearby residents from figuring out what was going on. Later, the company resold the homes but didn't disclose any information about the matter to the new buyers, according to the Tribune.

The Tribune stories were accompanied by a 1997 confidential memo written by the company's chief legal counsel, who said Kennecott ignored legal advice by failing to disclose information about the risk of tailings dam failure and its actions could be tatamount to fraud under Utah law.

A lot of the events described in the story happened in the late 1980s and 1990s.

The Tribune writers reviewed a lot of information from the mine's current owners and regulators indicating that the tailings dam now poses very little risk, thanks to the upgrades.

The Kennecott mine is now owned by the mining conglomerate Rio Tinto, a stakeholder in the Pebble project, and it is Rio Tinto's most profitable mine.

Here's a snippet from a statement that Kennecott published on Sunday about the tailings issue:

"We cannot answer questions about decisions of previous managers, many of whom are no longer with the company, nor can we verify if allegations in the confidential memo were true. What we can say is that today, we would have engaged our community stakeholders earlier in the process on such important issues that might affect them.

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