The wall of a reservoir filled with caustic red sludge will inevitably collapse and unleash a new deluge of toxic matter that could ooze a half-mile (1 kilometer) to the north, wreaking further havoc in the wake of last week's disaster, a Hungarian official said Sunday.
That would flood parts of the town already hit by the industrial waste Oct. 4 but stop short of the next town to the north.
Environmental State Secretary Zoltan Illes said that recently discovered cracks on the northern wall of the reservoir at the alumina plant have temporarily stopped widening because of favorable weather conditions but will continue to expand, especially at night.
Disaster agency spokesman Tibor Dobson said engineers didn't detect any new cracks overnight Saturday, and the older cracks were being repaired, but it was too soon to consider lowering the state of alert.
Protective walls were being built around the reservoir's damaged area to hold back further spills. And a 2,000-foot- (620-meter-) long dam that will be between 4 and 5 meters (yards) high was under construction to save the areas of the town of Kolontar not directly hit by last week's toxic flood.
"I would describe the situation as hopeful, but nothing has really changed," Dobson told The Associated Press. "The wall to protect Kolontar is planned to be finished by tonight, but it will likely be several days before residents may be able to move back."
Nearly all of Kolontar's 800 residents were evacuated Saturday, when Prime Minister Viktor Orban said the north wall of the massive storage pool — which is 24.7 acres (10 hectares) in size — was "very likely" to collapse because cracks that had appeared at several points.
The roughly 6,000 residents of neighboring Devecser, just north of Kolontar, were told by police Saturday to pack a single bag and get ready to leave at a moment's notice.
"This hasn't changed," Dobson said. "We are still on guard in case of any more spills."
Illes said that, since it would be impossible to transfer the 2.5 million cubic meters (568 million gallons) of red sludge still in the damaged reservoir, he had set a 2-month deadline for closing up the huge gap on its northwest corner through which the red sludge and caustic water had flowed out.
"The hole is 50 meters (yards) wide and 23 meters high," Illes said. "The job, including pouring enough concrete to raise three 10-story buildings, will have to be done from the air. This is unprecedented."
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, meaning it remained highly caustic.
Illes, commenting to reporters during a tour of the affected villages and the damaged reservoir, confirmed that the red sludge stored in Hungarian reservoirs had not been treated to reduce its alkalinity.
A five-member European civil protection team will start work in Hungary, helping to assess and advise on the impact of the alkali sludge on the environment, in particular on agricultural land, surface and underground water supplies as well as flora and fauna. The team will also anticipate risks and suggest solutions about restoring the nature and the agricultural and urban land affected.
"The quick selection of this team ... clearly shows that European solidarity is working," Kristalina Georgieva, the EU crisis response commissioner, said Sunday.
Last week, the sludge flooded three villages in less than an hour, burning people and animals. At least seven people were killed and at least 120 were injured. Several of those who were hospitalized were in serious condition. Around 184 million gallons (700,000 cubic meters) of the caustic red sludge was released.
The sludge devastated creeks and rivers near the spill site and entered the Danube River on Thursday, moving downstream toward Croatia, Serbia and Romania. But the volume of water in the Danube appeared to be blunting the sludge's immediate impact.
Illes said that neutralizing chemicals poured into primary and secondary tributaries of the Danube, as well as efforts to remove as much red sludge as possible from the waterways, was able to prevent ecological damage to Europe's second-longest river.
In Romania, local authorities were testing the water Sunday every four hours in the village of Bazias where the Danube enters Romania from Serbia, and will continue to carry out tests all this week, said Adrian Draghici, director of Romanian water for Mehedinti county.
Romanian fishermen sailed out into the Danube and villagers fished on the banks of the river for pike, which is plentiful in the Danube. They seemed unperturbed by any potential hazards.
But local authorities warned residents about letting animals drink from the Danube and urged them to be careful about fishing, as a precautionary measure.
The company that owns the metals factory, MAL Rt., expressed its condolences to the victims and their families Sunday and apologized for not having done so sooner.
"MAL Rt. is in full agreement with Prime Minister Viktor Orban that the actual parties responsible must be found and that MAL Rt. has to refund the damages in proportion to its responsibility," the company said in a statement.
Hungarian police have seized documents from the company, and the National Investigation Office is looking into whether on-the-job carelessness was a factor in the disaster.
State Secretary Illes said the fines accumulated so far by MAL because of the damage caused to waterways and the pollution spread by the flood totaled at least 19.2 billion forints ($97.3 million).
Associated Press writer Alison Mutler in Bucharest, Romania and Robert Wielaard in Brussels contributed to this report.