Tailings Dam Failure Model of Mirador Mine shows potential to take lives and contaminate large sections of rivers

In 2010, E-Tech received a request from the elected prefect/governor of the state of Zamora Chinchipe to analyze the environmental impacts of the Cordillera del Condor EcuaCorriente S.A. (ECSA) mine owned by Chinese government-dominated corporations. Since 2011, we have worked in Ecuador with technical experts assessing impacts from the ECSA copper open-pit Mirador mine at the request of communities, indigenous federations and confederations, regional governments, and the then Ministry of Environment (MAE). In 2011, we found ourselves helping the MAE respond to the draft Environmental Impact Assessment for Mirador exploitation and reviewing ECSA documents related to the planned 30,000 metric tons per day mine. We found much to be concerned about in this rainforest with high seismicity and tremendous rainfall; particularly we were concerned about potential tailings dam construction stability. By mid-2012, the MAE permit issuance was under the leadership of the ex-ECSA environmental chief. Since that time, despite many freedom of information requests by attorneys and the National Assembly for all specific documentation that could be utilized to analyze the approval of tailings facilities and other facilities within the mine, we have received only general information with no technical appendices. Transparency under the law has not translated to freedom of information.

Residents of this rainforest, home to hundreds of native Shuar people living in and along the rivers below the mine, are always in danger from flooding and earthquakes. E-Tech has had little success in obtaining presumably reliable technical information relating to potential dangers, impacts and means to mitigate impacts of the mine that is rapidly expanding nearly 5x to 140,000 metric tons per day of production – placing Mirador in coming years among the world’s largest mines. In order to make a credible guess at mine tailings impacts in the event of failure, we have used available information from agencies and the mining company, as well as photographs and credible geographical information, and have contracted a digital model by Riada Engineering of a potential tailings dam failure and subsequent results, using their FLO2-D model. Our results are available to anyone at the link below (after entering your contact information on the landing page). The FLO-2D model is one of only a few in the world approved for tailings dam modeling.

The model shows that failures of tailing dams at Mirador as a result of earthquakes, heavy rains, structural weaknesses, or lack of maintenance while the mine operates and after it closes, could take the lives of Shuar and other communities downstream of the mine which, as with all mines and tailings, require closure maintenance for centuries. The mine has 2 tailings impoundments holding saturated tailings: the smaller and earlier Quimi impoundment and the larger and more recent Tundayme impoundment. The FLO-2D software was used to simulate failures of the Quimi and Tundayme dams, using failure scenarios that varied from minimum to maximum releases. With 77% of the tailings full in the planned 260 meter tall Tundayme impoundment the consequences of a catastrophic failure would be extreme and the impacts extensive if it did occur, causing loss of lives and property, and contaminated rivers well downstream of the mine.

In the case of a failure of the Tundayme impoundment, catastrophic flooding is predicted from the dam to the confluence with the Rio Zamora. The flows would likely destroy bridges, buildings, and other infrastructure within the flood zone. The release would impact several communities with large tailings deposits up to at least 30 meters thick along the Rio Quimi valley to the confluence with the Rio Zamora. Tailings thicknesses on the Rio Zamora would reach 10 meters and extend for 10 kilometers downstream and 5 kilometers upstream of the Rio Quimi-Rio Zamora confluence.

Downstream, after the worst of the tailings deposits, a tailings collapse of that magnitude is modeled to continue on to enter the Rio Santiago, where it will at least carry sediment to the border of Peru.

Government officials and local communities need to know immediately where tailings from a possible failure will go, so that they can work with local communities to develop emergency response plans in this difficult area where Shuar indigenous people pretty much live in the river. The model can calculate how fast the tailings will move downriver in order to provide times for tailings to travel to a specific point in the event of dam failure, and can be used to plan ways to evacuate those areas. The state needs to take regulatory measures now to prevent dam failure, including immediate and continuous transparent audits of documents by a multisectoral committee of experts that should be made available to all who request them. Such audits must examine current mine tailings management practices to determine any feasible alternatives to avoid imminent endangerment to lives and the environment, and there must be comprehensive closure plans for the mine and its saturated tailings dams.

E-Tech was in Ecuador with Riada Engineering from October 24 through November 1 to conduct a free 3-day training at the Escuela Politécnica Nacional, spoke at press and public events and met with the Zamora Chinchipe prefecture on October 27. We attended meetings in Limon Indanza on October 29-30 with Shuar communities and with the GAD – local mayors and representatives of municipalities – to discuss how to best use the FLO-2D modeling to identify areas at risk and escape routes at as many specific locations as people lived. This process will continue and hopefully so will ongoing attempts to finally open up these issues with far more information available to the people impacted and technical experts.

On our final day in Ecuador, ECSA issued a “denuncia” of our work with very little substance other than insults. We welcome all information they can offer and the opportunity to work transparently with them. Beyond that we stand by our recommendations in bold above. A few days after this denouncement of E-Tech, according to media sources, the Tundayme dam was approved to grow to 320 meters in height – the highest in the world. In our opinion, this is a dangerous act of blindness, given the recent global failure of all types of tailings dams, and it deeply strengthens the urgency of a contingency response plan and open audit of Mirador.

Here is the link to the documentation on the study: https://flo-2d.sharefile.com/d-s8060752998494750a59c9c4eb065037f

A downloadable summary of the study in Spanish is available at this link.

E-Tech contacts in Ecuador 24 Oct-1 Nov: Richard Kamp +1 505 670 1337, Lupita de Heredia +57 321 387 8860, Ricardo Segovia +1 604 704 1232, Dr. Steven Emerman Malach Consulting; U.S.: Dra. Ann Maest +1 303 324 6948, Dr David Chambers CSP2 +1 406 599 0537

Tundayme 77% full tailings dam spill


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