A deadly dam burst at a Brazilian iron ore mine has triggered a civil lawsuit seeking 20 billion reais ($5.31 billion) in environmental and property damages from mine operator Samarco and its owners, BHP Billiton Ltd and Vale SA, Vale said in a securities filing on Monday. The National Humanitarian Society (Sohumana) has filed the lawsuit before a federal judge in Rio de Janeiro, Vale said. Brazil's federal and state governments have also said they will sue Samarco and its owners for 20 billion reais after a burst tailings dam last month unleashed 60 million cubic meters of mud and mine waste that devastated a village, killed at least 13 people and polluted a major river valley