Goldmine gamble's deadly outcome
1 November 2003
Mine managers knew a landslide was imminent but kept staff working below. Eight died.
The operators of the world's richest goldmine had more than two days' warning of the landslide that killed eight workers - but wrongly calculated that it would not be big enough to reach miners left working near the bottom of their pit.
According to information provided to The Age by investigators, managers at Freeport McMoRan knew the landslide was coming but figured it would be slow enough, and small enough, to stop on a 90-metre wide safety shelf, called a bench, cut into the pit wall above their workers.
Although heavy rain had fallen for five days leading up to the landslide, they didn't realise how much water was trapped in the slope and that the landslide would pour right over the bench and onto the workers below.
Three weeks later, four bodies remain buried under 2.5 million tonnes of rock and mud, somewhere at the bottom of the pit sunk more than 4000 metres high up in the mountains of Papua. Four other bodies have been pulled out.
Five people are recovering from injuries, including Muhammad Samsuri, now lying in a Townsville hospital bed after losing both legs.
Among many of the workers at the Grasberg mine, 16 per cent owned by Australian mining company Rio Tinto, there is deep concern about the disaster and whether more should have been done to avoid it.
A week after the October 9 landslide, Freeport chief executive Jim Bob Moffett sought to play down the size of the landslide and its impact on production when he addressed financial analysts.
"This can be cleaned up quickly once we are prepared to go in and give it full throttle," he said.
Although he promised Freeport would do what it could to find out what happened, he did not mention the data the company already had that showed a slide was imminent.
Because the south wall where the slide took place had always been at risk, the company had it rigged with more than 12 extensometers - devices that measure movement in slopes.
Every 20 minutes, any movement was recorded and graphed on a computer to show what the slope was doing. The results were discussed at meetings twice daily.
According to Dr Anthony Meyers, Australian liaison officer with the International Society of Rock Mechanics, small movements are not something to worry about. The danger comes if the rate of movement begins to accelerate.
In August and September, the rate of movement in the slope began to increase from around four millimetres a day up to eight millimetres and then 10 millimetres, before moving back down, according to one investigator into the accident, Witoro Soelarno from the Indonesian Department of Energy and Mineral Resources.
The Grasberg mine's standard operating procedures say that movement of more than 10 millimetres per day means "possible pit slope failure".
In the early days of October, the slope continued to pick up speed and by October 5 parts of it were moving 20 and 30 millimetres a day, Mr Witoro said.
On October 7, two days before the fatal slide, Freeport moved its stationary mining equipment on the 90-metre bench out of the zone where it expected the slide to hit.
But down below the bench, it was work as normal for the drivers of the mine's trucks and bulldozers, and mechanics like Muhammad Samsuri.
Just before dawn on October 9, he and two friends were working on a pump in the open when he looked up.
"I saw the mountain split into two. Then I ran, I was confused, I was nervous, where should I run to?" he said.
He and one friend headed for the only shelter within reach - a small water tank - while the other friend ran the opposite way. There was no way out for any of them.
Mr Samsuri was knocked unconscious by the rubble which buried him chest deep. He came to when officers administered drugs.
"The one next to me was already unconscious," he recalled. "I could only see his head. I think he was already dead.
"The other one, Budi Kuncoro, I could only hear him screaming for help. According to my wife, I am the only one who is alive from the three of us."
The chairman of mining engineering at Curtin University, Professor Peter Lilly, said such large loss of life is extremely rare in open-cut mines because slides usually can be predicted.
He said engineers knew the weak spots in mines and monitored them. If they started to move, the mine management moved workers out of the way. "You get a feeling it's going to happen and you get people out of there," he said.
Freeport and Indonesian investigators both say a liquid slide was never expected, which is presumably why the company did not move its workers out of the path of the landslide.
The Government's preliminary investigation found that seven devices, known as piezometers, that the company had in the slope to warn of water build-up were not in the right place to predict what happened.
Freeport had already mapped the water pockets in the area but managers were not worried about them because they normally drained themselves, Mr Witoro said.
Given that history, Freeport could not have predicted what happened without monitoring those pockets.
"So far there has been no experience like this . . . Usually there are many cracks in this, water comes out. But not this time. Now, the water comes in and stays there," Mr Witoro said.
He does not blame Freeport for putting workers down at the bottom when they knew a slide was coming because "the systems seemed to work well."
But now major changes, including the use of drainage systems, may be needed to keep water out of the slope before mining would be allowed to resume, he said.
"Freeport will have to present a concept to the director-general (of Indonesia's Mines Department). If the director-general agrees, they can go on; if not, they can't."
Freeport declined to respond to questions from The Age about the evidence a slide was imminent or what considerations they gave it.
"We have always been . . . committed to safety in all phases of our operations," the company said in a statement.
Matthew Moore and Karuni Rompies,
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