A recently published report, coordinated by the Government of Indonesia’s Ministry of Research, Technology and Higher Education, concluded that Newmont’s former Mesel gold mine in North Sulawesi, Indonesia – which ceased production in 2004 – responsibly managed tailings disposal at the operation.

Monitoring conducted as part of a 10-year post-closure program by environmental toxicologist Keith Bentley and medical specialist and Director of the Eijkman Institute, Amin Soebrandrio – members of the Independent Scientific Panel (ISP) – found that the local communities from the region consuming fish and other marine seafood had not been adversely impacted from submarine tailing disposal. Levels of arsenic and mercury were at natural levels and below the Australia New Zealand (FSANZ) food standard (for arsenic) and FAO/WHO Codex 1991 (for mercury), further demonstrating that the fish are safe for human consumption. Tailings are the residual materials from mined and crushed ore after valuable minerals have been recovered.

Newmont’s now reclaimed Mesel mine was in operation from 1996 to 2004. After production ceased, some non-governmental organizations and community members expressed that the mine’s subsea placement of detoxified tailings had adversely impacted public health and the local marine environment, including the fishing industry and marine tourism. Multiple independent studies, including by the World Health Organization, have demonstrated that Newmont’s responsible tailings management and mine closure has left Buyat Bay in a stable environmental state and that residents of Ratatotok remain safe to continue consuming fish harvested from the bay. In fact, the former mine site is now designated a botanical garden, the first of its kind in Indonesia, and the bay is a highly regarded recreational diving destination.

To prevent contamination, Mesel detoxified its tailings before safely disposing of them in a designated subsea location. The process involved residual cyanide removal and using ferrous sulphate and sodium sulphide precipitation to remove naturally occurring arsenic and mercury from the liquid fraction of the tailings. The remaining tailing material (slurry) was then deposited via pipeline onto the subsea floor at Buyat Bay in a 1.3-square-kilometer embayment at a depth of 82 meters, nearly one kilometer from the Ratatotok shoreline. The tailings management process – as is the case at other Newmont operations – was engineered to safely store tailing materials.

Following Mesel’s closure in 2004, Newmont and the Government of Indonesia established an independent panel of scientists, the ISP, to conduct a 10-year post-closure study to monitor fish tissue, marine ecology, and physical and chemical oceanography. Completed in 2016, the program demonstrated that Mesel’s subsea tailings placement activities were a major success in sustainable mining: arsenic and mercury levels in biota were consistently below their respective standards, and fish sources were healthy and abundant.

Now, 13 years after Mesel’s closure, fish and other marine seafood remain safe and are essential pillars of the local diet, while fishing and marine tourism continue to contribute to the local economy.

To learn more about Newmont’s mine closure and reclamation efforts, please visit Beyond the Mine.

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