Victims of Brazil’s worst environmental disaster have turned to a United Kingdom court for compensation, almost nine years after tonnes of toxic mining waste poured into a major waterway, killing 19 people and devastating local communities.

The class action lawsuit at the High Court of Justice in London on Monday seeks an estimated 36 billion pounds ($47bn) in damages from the global mining giant BHP. That would make it the largest environmental payout ever, according to Pogust Goodhead, the law firm representing the plaintiffs.

BHP owns 50 percent of Samarco, the Brazilian company that operates the iron ore mine where a tailings dam ruptured on November 5, 2015, releasing enough mine waste to fill 13,000 Olympic-size swimming pools into the Doce River in southeastern Brazil. The case was filed in the UK because one of BHP’s two main legal entities was based in London at the time.

“BHP is a polluter and must therefore pay,” lawyer Alain Choo Choy said in written submissions.

BHP lawyer Shaheed Fatima said in written submissions that the claim has “no basis”,  adding that BHP did not own or operate the dam and “had limited knowledge of the dam and no knowledge that its stability was compromised”.

The river, which the Krenak Indigenous people revere as a deity, was polluted so badly that it has yet to recover. The disaster killed 14 tonnes of freshwater fish and damaged 660km (410 miles) of the Doce River, according to a study by the University of Ulster.

When the dam known as Fundao broke, sludge washed over Bento Rodrigues, once a bustling village in Minas Gerais state. Now it resembles a ghost town.

A few white tiles are the only remnants of the house where Monica dos Santos, 39, lived with her parents near the Catholic church that also was destroyed. She has become one of the principal activists seeking full reparations.

“It’s not just the destruction of November 5. The destruction since, I often say, has been worse,” she said. Some survivors turned to alcohol, others to drugs. Personal relations were strained, sometimes to breaking point.

Negotiating settlements

The trial comes days after BHP announced that the company and its partner in Samarco, Vale SA, were negotiating a settlement with public authorities in Brazil that could provide $31.7bn for people, communities and the environment damaged.

Vale on Friday said the sum included $7.9bn already paid, $18bn to be paid in instalments over 20 years to Brazil’s federal government, Minas Gerais and Espirito Santo states and municipalities, and $5.8bn in “performance obligations” by Samarco, including individual compensation.

Last month, President Luiz Inacio Lula da Silva told Radio Vitoriosa, a local station in Minas Gerais, that his administration was aiming to reach an agreement with the mining companies by the end of October. Claims were filed by Brazil’s Federal Public Prosecution Office and public authorities.

The Australia-based BHP in Melbourne said it believed the UK action was unnecessary because it duplicated matters covered by reparation efforts and legal proceedings in Brazil, but said it would continue to defend it.

Pogust Goodhead said the potential settlement should not have any impact on the case.

“Such timing only proves that the companies responsible for Brazil’s biggest environmental disaster are determined to do everything they can to prevent the victims from seeking justice,” the firm said in a statement.

Survivors from Bento Rodrigues have moved to a new village of the same name a half-hour drive away. Colourful, multistorey houses line freshly paved streets.

Priscila Monteiro, 36, moved in three months ago but said she did not feel at home.

“It feels like I’m just passing through and I’m going to go back home any minute,” she said.

Monteiro was pregnant when the dam broke on her birthday. She and her two-year-old were pulled from the toxic slime and survived, but she had a miscarriage. Her five-year-old niece, Emanuelle, died.

“For me, the day that was supposed to be a celebration has become a day of mourning, forever,” she said, crying.

Monteiro says she hoped the trial in London would lead to recognition of the damage.

“God put the people from London on our path because there is no justice in Brazil. Now our last hope is them,” she said.