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After an interminable fraction of a second, the ground beneath the truck started to move again, this time tilting, sliding down and away from the wall towering above it. For the first time Candelaria felt the movement, a sickening sensation he likened to a boat pushing away from a dock. He looked up.
"All of a sudden the mountain that was on my side starts rolling like surf," he says wondrously. "First I can see it crawling up the side of the truck and then rolling over and across the top."
The windshield and the passenger-side window were buried. Candelaria looked left out of the driver's window.
"That's when I knew I was in deep shit," he says. "I'm level with the damn tailings, and it's like a damn wave pumping down the side of the canyon."
Candelaria got out of his truck and "hiked out of that mother."
If he escaped unharmed, the delicate riparian area below was not so fortunate.
For the next 30 minutes, the slime rolled over itself like lava, down the hillside from mine property into the Tonto National Forest. After traveling a quarter mile and descending 400 vertical feet, it reached Pinto Creek and flowed upstream as far as gravity would allow, then turned downstream. Beneath the chute it was 42 feet deep; at its farthest point, three quarters of a mile downstream, it was eight feet deep, and then it stopped abruptly.
Pinto Creek is an intermittent stream. Parts of it run year-round; parts don't. The spill occurred on a dry stretch during a dry season. If the stream had been running top to bottom, the flow would have carried the tailings farther downstream. Although the tailings material is not particularly toxic, it has such fine particles that it could suffocate any plant or animal life in the water.
After the tailings stopped, slimy liquid poured out of the mass and coated everything downstream--the dry streambed interspersed with perennial pools--for another three quarters of a mile.
Russell Haughey, a habitat biologist from the Arizona Game and Fish Department, walked the length of the spill in the days following the accident.
"Up above, it was the consistency of drywall mud," he says. "Farther down, there was water flowing, but there were a lot of fine [particles] and it would form the consistency of pudding."
Haughey found some dead fish atop the pudding; others seemed to be swimming in it. Turtles and lizards skittered on the surface. Haughey found prints where larger mammals had struggled through.
In its earliest reports, the U.S. Forest Service estimated that the spill would be cleaned up within a month. It was not to be.
Nonetheless, BHP moved quickly. The company brought in its own top talent and recruited from its extensive properties the world over. It transferred one of its best engineers, Mahmoud Yasin, from a mine in Peru because of his earth-moving experience. It asked the Forest Service and the other agencies to refer the best restoration ecologists available and then hired them. It brought in an army of about 200 workers, put them on earth movers and handed them shovels and buckets and started them all digging.
In early April, Pinto Creek bore an eerie resemblance to the construction on the northernmost stretches of the Squaw Peak Parkway. Bulldozers, earth movers, haul trucks, dwarfed by the canyon walls, rolled along the canyon bottom where the stream once ran.
There had been no question on the part of the mine company officials or on the part of the biologists and enforcement specialists of the state and federal regulatory agencies that BHP was going to have to clean up its mess.
"We have a statutory responsibility, but we have a moral and ethical responsibility to respond quickly and decisively to see that this thing is contained as soon as possible," says Dee Durazo, the mine's general manager.
But no one had ever undertaken a cleanup of this nature. Countless tons of semisolid material had to be hauled out of an inaccessible canyon, and then a sensitive riparian ecosystem had to be restored.
The first challenge was to contain the spill, and so the engineers built temporary dams called gabions at the bottom of the semisolid mass and at the farthest point of contaminated stream water, and then installed pumps and pipe so that they could pump all of the tainted water out of the streambed and up to the mine property.
In order to keep winter and spring flows from hindering the cleanup and carrying any tailings material downstream, they built a dam 53 feet high and 500 feet wide upstream from the spill. The water that backed up behind it was then pumped through flexible plastic pipe that ran up over the hillside and dumped back into the creek two miles downstream. A 36-inch-thick pipe ran through the canyon alongside the tailings, a hedge against heavy rains, in case water had to be released quickly. The pumps behind the dam could move 11,000 gallons per minute.