"Somehow it seems that Indonesian lives aren't worth the same as Chinese lives," said Emerman, the hydrologist.
Achmad Zulkarnaen, a BRM spokesperson, did not deny the geological stability issues but said the risks were manageable.
Two layers of geomembrane would prevent water from reaching the wall of the dam, he said, adding that failed dams represent "only a small portion" of tailings dams around the world.
In fact, a study published in the journal Nature Scientific Reports in March looked at 1,743 tailings facilities and found 10% have reported "notable stability concerns" at some point in their history.
Zulkarnaen said the dam was designed to hold back a 100-year flood — and not the minimum industry standard 10,000-year flood — because the Indonesian government does not have data stretching back further.
The nearest weather station only has 10 years of data, and the next closest station with 30 years of data is hundreds of kilometers away at a different elevation, Emerman said.
That lack of data calls for tighter standards, not looser ones, he added, calling into question the reliability of even the 100-year-flood projection.
Together with Indonesian NGO Bakumsu, villagers have submitted a formal complaint to the IFC, the private finance arm of the World Bank, which is linked to the project through an investment in the Postal Savings Bank of China, which lent money to NFC.
The IFC did not respond to requests for comment.
Still, villagers are divided on what should come next. Jaben Sihaloho, an entrepreneur, said he would welcome DPM if residents were relocated away from danger and properly compensated.
i"Those who are supporting the mine depend on DPM for their livelihood," he said. "We, on the other hand, still have our agricultural land."Dapatkan update berita pilihan dan breaking news setiap hari dari Kompas.com. Mari bergabung di Grup Telegram "Kompas.com News Update", caranya klik link https://t.me/kompascomupdate, kemudian join. Anda harus install aplikasi Telegram terlebih dulu di ponsel.