Investigation of the causes
On the first quarter of November 2015, the Brazilian Chamber of Deputies and the state chambers of Minas Gerais and Espírito Santo each created a special commission to investigate the collapse. According to the media reports, many of the deputies that composed such commissions had received donations from Vale to finance their campaigns. Such donations, up to R$2.6 million are legal, and were reported by the then-candidates to the Brazilian Election Justice. However, critics argued that the deputies' participation was clearly biased.[25][26]
In January 2016, leaked internal documents from 14 months before the disaster revealed that Samarco had been warned about the possibility of the dam collapsing.[27] Joaquim Pimenta de Ávila, an engineer who was regarded as one of the foremost tailing dam engineers in Brazil, had been contracted by Samarco between 2008 and 2012 to design and oversee the construction of the Fundão dam.
From 2013, Ávila was hired part-time as a consultant to inspect the dam, and a technical report he wrote from September 2014 lists severe structural problems on the dam (in the form of cracks) and measures to mitigate them, the main one being the construction of a buttress. Ávila originally designed the dam in 2006, and it was erected by construction firm Camter. However, construction defects within the dam led to a design change by Camter that allowed for more saturation.[28] Samarco claimed to have implemented all the recommendations from Ávila, and that the dam was in the process of being heightened when the impoundment reached its maximum holding capacity and began to leak. However, Samarco failed to comment specifically about the buttress, and claims that it was never warned about the severity of the structural damages, nor about the imminence of a catastrophic failure.
In August 2016, the report of an investigation panel constituted by Samarco and its shareholders was published online.[29] The investigation panel findings indicated that the liquefaction flowsliding resulted from multiple factors, including an increase in the saturation of the tailings due to modifications in the design of the dam and the presence of soft slimes in unintended areas on the left abutment of the dam. Another study indicated that the dam failure could not be predicted based on simple limit equilibrium analyses and that only a complex failure mechanism would explain the dam collapse.[30]
Sanctions to Samarco
The Minas Gerais government suspended Samarco's activities immediately after the disaster.[31]
Next, the Brazilian government fined Samarco BRL250 million (US$66.3 million) for the incident.[32][33] The fine was preliminary and was expected to be increased if the two companies were found guilty of water pollution and damages.
Succumbing to external pressure, BHP Billiton, together with Vale and Samarco, signed in 2016 an agreement with the Brazilian federal and state authorities. In January 2016, the Brazilian government and Samarco reached an agreement and a fine of BRL20 billion (US$4.8 billion) was issued.[34] The penalty did not include compensation to people affected by the disaster, and the cost of recovering the polluted area.
Legal consequences
Vale and BHP Billiton own Samarco as a joint venture, with each company possessing a 50% stake.[36] As of 2018, the companies remain in negotiations with Brazilian authorities in efforts to settle out of court.
In March 2016, Samarco agreed to pay US$2.3 billion in compensation. Australia's ABC reported that Samarco and its joint venture partners would "establish a foundation to develop and execute environmental and socio-economic programs to restore the environment, local communities and social conditions of the affected areas."[37]
In June 2016, an AUD$8 billion civil suit which was reinstated by Brazil's Superior Court after the original agreement was suspended. BHP, along with its Samarco joint venture partner Vale, face a separate $55 billion suit lodged by federal prosecutors.[35]
In October 2016 it was reported that Brazilian prosecutors had filed manslaughter and environmental charges against 21 people[38] including top executives of Samarco's Parent Companies:
Class action lawsuits
In August 2018, BHP settled a class action suit in the US for US$50 million, with no admission of liability.[41] At the same time, it was facing a class action lawsuit from shareholders in Australia related to the dam failure[42] and losses incurred by shareholders following company disclosures to the market regarding the safety of the dam. The class action is expected to be one of the largest in Australian history, with 30,000 BHP shareholders involved, with a combined shareholding of 330 million shares, valued at over AU$10 billion (at 30 October 2018).[43]
In November 2018, UK-based legal firm SPG Law, now Pogust Goodhead, filed a US$5 billion group action in the High Court of Justice at Liverpool under Brazilian law against BHP Billiton on behalf of 235,000 Brazilian individuals and organisations, including municipal governments, utility companies, indigenous tribes and the Catholic Church.[44] The lawsuit is one of the biggest legal claims ever filed in a British court.[45]
Government settlement agreement
On 25 October 2024, mining companies BHP and Vale signed an agreement with the Brazilian government to pay nearly US$30 billion in compensation over the Mariana Dam collapse. The terms include $18 billion in funding for public authorities and $5.6 billion in additional compensation, resettlement, and environment restoration. The signing ceremony was attended by Brazilian President Luiz Inacio Lula de Silva.[65]
There is speculation that the agreement could end more than one hundred lawsuits against the mining companies in Brazil, and possibly limit legal action abroad. Vale's vice-president for corporate and external affairs, Alexandre D'Ambrosio, indicated that the compensation deal undermines the foundation of the London case.[66]
On 6 November 2024, the Supreme Federal Court (STF) unanimously validated the agreement reached by the federal government, the states of Minas Gerais, Espírito Santo and mining companies to repair the damage caused by the Mariana dam collapse.[67]
