Towns fear second wave of toxic sludge

The wall of a reservoir holding the remaining 500,000cu m of toxic sludge at a Hungarian alumina plant has cracked and could soon break, unleashing a fresh corrosive torrent.

The 715 residents of Kolontar, the first town in the path of any new spill, have been evacuated, and 5400 people in Devecser have been told to pack belongings in a single bag and be ready to leave.

Hungarian Prime Minister Viktor Orban said: "The Interior Minister informed us that cracks have appeared in the northern wall of the reservoir, whose corner collapsed.

The detached parts of the dam are growing apart. The distance between them widened by 7cm so it is very likely that we have to reckon on this wall collapsing."

Crews are building a new dam up to 5m high in Kolontar to ward off any fresh inundation, and more than 300 soldiers, 127 vehicles, and five trains are on standby to evacuate the larger town of Devecser.

These latest, troubling developments came five days after the initial spill sent 840 million litres of the red sludge into three villages and the adjoining countryside.

Within only a few hours, the spill was not far short of the volume of oil leached into the Gulf of Mexico by the Deepwater Horizon disaster. It claimed seven lives and left 150 injured.

The sludge, a byproduct of bauxite mining containing arsenic and lead, entered the Marcal River, killing all life. It then passed into the Danube, one of Europe's most important waterways.

There are conflicting reports of the effects of the disaster. Fears that the Danube's fish, molluscs, and plants could be killed, and drinking water contaminated, have been allayed by tests of the river's water quality.

These, taken every few hours, show that the concentration of heavy metals has dropped to the level allowed in drinking water.

Hungary's disaster agency said the pH level of the water where the slurry entered the Danube was less than nine - well below the 13.5 measured earlier in local waterways near the site of the catastrophe, and sufficiently diluted to prevent any biological damage, a minister said.

Yet Greenpeace officials said that tests they have commissioned of the sludge's effect on farmland show "surprisingly high" concentrations of arsenic and mercury. Their analysis suggested that roughly 50 tonnes of arsenic, 300 tonnes of chrome and half a ton of mercury was unleashed by the spill. The group's officials said the detected arsenic concentration was twice the amount normally found in so-called red mud, a waste product in aluminum production.

The concern now is that any further collapse in the reservoir walls would liberate industrial slurry with far higher concentrations of toxins. Hungary's environmental chief, Zoltan Illes, said that dry warmer weather would turn the caustic mud to airborne dust, which could cause respiratory problems. Emergency officials urged residents to wear face masks.

A more sanguine view was taken by the Hungarian Academy of Sciences, which reiterated that the red sludge remained hazardous due to its caustic alkalinity, but that its heavy metal concentrations were not considered dangerous.

- INDEPENDENT