DEVECSER, Hungary — The cracking wall of an industrial plant reservoir appeared on the verge of collapse Saturday, and engineers were working to blunt a possible second wave of the red sludge that has deluged several towns in western Hungary and killed seven people.
Residents of one nearby town were evacuated, others were ordered to be ready to evacuate, and everyone was bracing for a new onslaught of toxic material. Engineers feared a second wave could be more toxic than the first because the sludge remaining in the reservoir was more concentrated.
"If another wave comes, I was thinking of standing on top of the kitchen table," said Maria Gyori, a 79-year-old homemaker in the town of Devecser. "Maybe the sludge won't go that high."
Prime Minister Viktor Orban said the northern wall of MAL Rt.'s storage pool, which released at least 184 million gallons of caustic red sludge and water on Monday after one of its corners ruptured, was showing numerous cracks.
Engineers were building retaining walls around the previous breach and the weakened wall of the reservoir just outside Kolontar, the town hardest hit by the sludge. Kolontar's 800 residents were evacuated Saturday as a preventive measure.
On Monday, the highly polluted water and mud flooded three villages in less than an hour, injuring at least 120 people.
Orban said experts had estimated that about 131 million gallons of red sludge could escape from the reservoir if the wall collapsed, but said exact figures were hard to calculate.
"We have no exact information about the nature of the material because a catastrophe like this has never happened before anywhere in the world," Orban said.
Red sludge is a byproduct of the refining of bauxite into alumina, the basic material for manufacturing aluminum. Treated sludge is often stored in ponds where the water eventually evaporates, leaving behind a largely safe red clay. Industry experts say the sludge in Hungary appears to have been insufficiently treated, if at all, and remained highly caustic.