Oyu Tolgoi’s tailings storage facility (TSF) emerged as yet another significant environmental threat in 2015 with little action taken until in November 2021 when Oyu Tolgoi (OT) formally admitted a seepage incident from the TSF seepage collection facility. Only in October 2023, two years later its lenders IFC and EBRD’s auditor classified the leakage of the first tailing cell (TC1) as an environmental incident. This leakage is a result of OT not conforming with the design requirement to discharge tailings with 62-64% solids and less than 38% water to the TSF. Instead, for years it has discharged tailings with far larger 42-45% water content resulting in wasted precious desert water and contaminated seepage. The auditor, Independent Environmental and Social Consultant (IESC) now recognizes non-conformance as summarized from its reports in the below table.
This video shows the two thickeners that are not thickening the tailings to 64-65% solids at Oyu Tolgoi. (Credit: D. Tserenjav, OT Watch Board member)
What does this mean for nomadic pastoralists and water resources?
This calculation is based on OT processing around 120,000 tons of ore per day and mixing it with 120,000 tons of water to achieve a 50:50 solids-water mix for the concentrator. This means that each excess 1% water left in the tailings is about 1,200 tons of water every day. Multiplied by 365 days this means 438,000 tons of water is left in the tailings or flows out in seepage to shallow aquifers.
Nomadic herders together with their advisers have been protesting, negotiating and monitoring OT’s promises since 2010 over drying wells, TSF seepage and water quality in shallow aquifers near it, until we’re blue in the face. Oyu Tolgoi continues to waste waters which should go to downstream users as well as continuing to build TC2 and plans for TC3 and TC4. Dry-stacking and improved thickeners are deemed too costly, while wasting desert waters is much cheaper and thus the company’s preferred option. Rio Tinto’s operations on the ground contribute to already steep desertification and climate disasters in Mongolia and globally.
Instead of planning dry-stacking and improving the thickener technology to eliminate non-conformance on achieving 64-65% solids in the tailings, Rio Tinto is again looking at transferring water from northern rivers. In 2022, Rio Tinto promised not to use Orkhon River waters, but in 2025 it paid 3 million dollars for the feasibility study of the Kherlen River water transfer project.
In addition, Rio Tinto refuses to pay water pollution charges, claiming that the Financial Stabilization clauses of the 2009 Investment Agreement cover all new charges regardless of the Mongolian government’s demands for compliance with the 2012 Law on Charges for Water Pollution.
Asks of investors to Rio Tinto
Rio Tinto/Oyu Tolgoi must take the following actions:
- Ensure the Oyu Tolgoi project complies with the technical requirements of 64-65% solids in its tailings and the GISTM.
- Revise planning for TC3 and TC4 plans and introduce dry stacking (GISTM) of tailings as a real climate change solution.
- Urgently implement the key recommendations made in the Water Efficiency Workshop in September 2024 to reduce water loss in the South Gobi Desert.
- Stop financing plans to divert fresh water to Oyu Tolgoi and Tavan Tolgoi (coal) mines from Orkhon and Kherlen rivers.
- Pay water pollution charges as well as reduce discharge of polluted water through seepage of tailings dams.
For more information please contact: Sukhgerel Dugersuren at otwatch@gmail.com.