An industrial accident at a caustic waste reservoir chain took place at the Ajkai Timföldgyár alumina plant in Ajka, Veszprém County, in western Hungary. On 4 October 2010, at 12:25 CEST (10:25 UTC), the northwestern corner of the dam of reservoir number 10 collapsed, freeing approximately one million cubic metres (35 million cubic feet) of liquid waste from red mud lakes. The mud was released as a wave, flooding several nearby localities, including the village of Kolontár and the town of Devecser. Ten people died, and 150 people were injured. About of land were initially affected. The spill reached the Danube on 7 October 2010. It was not initially clear how the containment at the reservoir had been breached, although the accident came after a particularly wet summer in Hungary, as in other parts of central Europe. Police have seized documents from the Ajkai Timföldgyár plant, although a spokesman for MAL Hungarian Aluminium (MAL Magyar Alumínium Termelő és Kereskedelmi Zrt.), the company that operates the plant, said the last inspection of the pond had shown "nothing untoward". Hungarian Prime Minister Viktor Orbán stated that the cause of the spill was presumably human error. Origin of the mud The red mud involved in the accident is a waste product of the Bayer process, which refines bauxite into a form of aluminium oxide called alumina. The mud primarily contains non-aluminium compounds present in the bauxite ore and left as residues after its refining along with sodium hydroxide used to dissolve aluminium oxide. Iron(III) oxide, the compound from which the red colour originates, is the main component, but it also contains other compounds. The mud, which is highly alkaline when it is first produced, is stored in large open-air ponds; It is thought that there are about 30 million tonnes of red mud stored around the Ajkai Timföldgyár plant. According to a press release by MAL, the mud had the following chemical percentage make-up (which expresses the amounts of different elements, not necessarily the actual solids). Unlike many other mine tailings, red mud does not contain very high levels of heavy metals, although still about seven times the levels in normal soil. Analyses of the mud at Kolontár on behalf of Greenpeace showed levels of chromium 660 mg/kg, arsenic 110 mg/kg and mercury 1.2 mg/kg. The Hungarian government has stated that the mud is "not poisonous", and the Hungarian Academy of Sciences stated