Posted by GlacierHub on Feb 17, 2015
In light of the Mount Polley tailings dam spill in British Columbia, Canada, environmental activists in Kyrgyzstan are ringing alarm bells over a possible scenario of a similar outburst at Petrov Lake near the Kumtor gold mine project. At Mount Polley, the tailings dam at a copper and gold mine burst in August last year, spilling 25 million cubic meters of toxic waste into nearby lakes. The British Columbia provincial government appointed a commission to probe into the disaster. The commission has concluded that a “dominant factor in the breach of the Mount Polley tailings dam was a failure in the dam’s foundation”. All the while in Kyrgyzstan, the main concern has been and still is the Kumtor project’s chemical waste tailings pond, managed by Centerra Gold. Coincidentally, the very same engineering firm of record for the Mount Polley dam, AMEC, was hired to investigate the Centerra Gold’s environmental record at Kumtor mine in 2013.
The most worrisome issue at Kumtor has been evolving with the stability of the glacial Petrov Lake, which is situated in direct proximity (7 km) above the tailings pond. The northwestern perimeter of Petrov Lake, where the dam is the narrowest, has become a major cause for concern in the Kyrgyz environmentalist community. The length of this particular section is approximately 30 meters. A Petrov Lake outburst could be expected to wash away the Kumtor tailings. where 60 million tons of cyanide liquid waste has been collected and stored so far. Just as in the case with the design of the Mount Polley dam, Kumtor tailings pond’s flawed feasibility has led to the instability of the dam and to seepage of toxic substances into the groundwater. The first report of the movement of the Kumtor tailings dam was recorded in 1999. And it was found that in the initial stages of the construction, the active layer of relatively unstable alluvial deposits had not been removed from the base of the tailings pond. That has made the remaining loamy interlayers (at depths of 4 to 6 meters) alsovulnerable to instability. The Prague-based group CEE Bankwatch has indicated that “in spite of measures to stabilize the dam in 2003 and 2006 (so-called shear keys and toe berm), the dam is still continuing to move.”
As this statement suggest, the company’s plans have not solved the issue of the tailings dam stability. An underlying issue is that the plans to store and manage the tailings from Kumtor did not include a hydrogeological study of the chosen location. The storage pond was built on the riverbed of the Arabel creek. It was later discovered that an old bed aquifer remained at a depth of 6.85 meters. This active bottom (underflow) is contributing to the instability of the tailings dam. Dr. Robert Moran, a hydro-geologist who visited the Kumtor mine in 2012, said that the tailings dam instability was “enhanced by the relatively high temperatures of the tailings when they come from the process plant (a highly contaminated mix of about 50% solids, 50% liquids), which would increase permafrost melting [in this high-elevation location]. Such deformation and movement of the tailings structure, combined with the partial melting of the permafrost raises concerns about a catastrophic failure of the tailings impoundment — especially if a severe earthquake were to occur [in this seismically-active region].”
Dr. William T. Colgan, a researcher with Geological Survey of Denmark and Greenland, believes that Petrov Lake presents an “additional geotechnical hazard confronting the Kumtor tailings pond”. According to Colgan’s analysis, “glacial moraine and till is often a poorly consolidated material, outburst floods from proglacial lakes due to berm breaches present a non-trivial hazard. Petrov Lake is one of approximately fifteen proglacial lakes in Kyrgyzstan for which the moraine dam has been classified as ‘at risk of rupture’ by previous researchers. The stability of the lake is important for the stability of the Kumtor tailings pond, as an outburst flood could result in failure by over topping of the downstream Kumtor tailings pond. The lake has grown in size from an area of 1.8 to 3.4 km² between 1977 and 2014. In 1957 it was just 0.96 km2 in area. This growth is due to climate change, which has enhanced both the retreat and melt of Petrov Glacier. This multi-decadal growth indicates that the volume of Petrov Lake is not in steady-state (whereby lake inflow is balanced by lake outflow), and thus the forces being exerted on moraine and till berms are likely changing over time.”
The threat of the environmental disaster over Kumtor tailings pond was highlighted at the United States House of Representatives Committee on Foreign Affairs Subcommittee hearing by Dr. Amanda Wooden (Associate Professor of Environmental Politics & Policy, Bucknell University) in November 2014. Wooden’s testimony has indicated that the “changes in the permafrost underneath this extensive tailing pit at the headwaters to the Naryn River and breach threats to Petrov Lake above the tailing pond are concerns that should be monitored”. Moran believes that in the scenario with Kumtor tailings dam failure, it would rapidly release “masses of contaminated water and sediments (the tailings) into the Kumtor river, endangering downstream people, facilities, downstream rivers, and would likely kill much of the mountain trout population and other aquatic organisms. Such a collapse could negatively-impact waters throughout much of the Naryn River basin, which flows into Uzbekistan.”
In sum, the tailings pond at Petrov Lake, with large quantities of toxic substances in an unstable glacial environment, represents a serious threat to the ecosystems and human populations in two countries. The efforts of environmental activists may serve to bring this serious risk to attention within these countries and beyond, pressing for tighter and more effective regulations.
For other stories on mining risks in glacier regions, look here and here.