On Thursday 5th November 2015 the collapse of a dam in Minas Gerais (Brazil) created the worst mining accident in the history of the country. Now, almost one month after, the damage continues to grow.
On the 5th of November two mining dams at Minas Gerais, Fundão and Santarém, collapsed discharging 62 million cubic meters of mud over the small village of Bento Rodrigues and into the river Doce, Bento Rodrigues. The homes of 600 people were destroyed by the mud. The disaster left 13 dead and 7 missing. Those who survived had their homes and lives destroyed. The Company Samarco, owner of the two dams, will have to provide new homes and compensation for the victims who have lost everything. Many also lost their livelihoods. They were farmers or fishermen and depended on environmental amenities that no longer exist. The families are now living temporarily in hotels in the district, and although no home can ever replace Bento Rodrigues in the inhabitants’ memories, a new definite home must be provided as soon as possible.
The impact of the dam burst did not stop there. The mud made its way into the river Doce affecting its aquatic system, flowing for more than 500 km, crossing the states of Minas Gerais (MG) and Espirito Santos (ES), until it reached the sea. Doce is one of the 100 largest rivers in the world and it is home to several endemic species not found anywhere else. Some communities got together to collect fish into tanks in an attempt to save some of those species at risk. Ibama, the Brazilian Institute of Environment and Renewable Natural Resources, reported the death of 3 tonnes of fishes in the river.
Moreover, the water supply from the river Doce was interrupted temporarily due to the unknown composition of the mud. This created a great mobilization effort to donate and send drinking water to the cities affected. The analysis of water samples collected at Governador Valadares, Minas Gerais, showed shockingly high concentrations of iron, arsenic and manganese, but the risk of contamination by mercury and lead was excluded. The water treatment had to be changed but now the water distribution system is operating again.
A major risk was the mud reaching the sea, because several environmental protection areas are located close to the river mouth and they could be damaged. Authorities required a plan from Samarco to contain the mud and avoid a disaster in the sea. The response was a buoy containment barrier at Regência, a method used conventionally to limit oil spills. However, it only avoids the dispersion of materials that are lighter than the water and are in the surface; therefore, it is not really useful for the mud which is dispersed through the water column. The mud flowed 10 km into the sea and has moved over 43 km North pulled by wind and water streams. Estuaries, where rivers meet the ocean, are known as the cradles of marine life. Many species use these areas for their reproduction and any environmental impacts might put several species at risk.
This is the case of sea turtles: for them the disaster could not come at a worst time. November is the turtles’ spawning month. Turtles always come to the same beach where they were born to give birth. The leatherback sea turtles, which are under the risk of extinction, choose the Regência beach to lay their eggs. The Tamar Project (http://www.tamar.org.br/interna_ing.php?cod=63) promotes the recovery of the five endangered sea turtle species that occur in Brazil. To save the species from the mud contamination they transported the baby turtles from the original site to southern uncontaminated beaches where the turtles could be released. This might not be enough, but the biologists affirm that it is better than no intervention.
Samarco is facing charges for all of the damage to people, economy and environment. Ibama studied the impacts on the environment and identified that the mud destroyed 100,000 km2 of vegetation, including permanent preservation areas and over 77 kilometers of rivers. Therefore, the fine for the environmental damage to Samarco and it owners, Vale and BHP Billiton, was evaluated in R$ 1 billion (approximately $ 260 millions). However, this does not represent all the total damages. The damage to the cities, the population and economy will impose a heavy charge to the three companies. The amount is not small and it was argued that this burden on the mining sector is going to affect the country’s already fragile economy.
President Dilma Rousseff said this Monday at the COP21 that “the irresponsible action of some companies caused the greatest environmental disaster in the history of Brazil in the area of the River Doce.” However, a question that has no answer yet, is the actual cause of the disaster. Historically, many other mining dams collapsed over the world for many different reasons. The dam in this case was built with compacted soil and the main concern for this kind of dam is the effects of erosion over time. However, the reason for the catastrophic rupture has not been firmly linked to erosion. There are many questions, but one thing is agreed: maintenance and supervision are essential. In Brazil, the security policy for dams was established only in 2012, but most of the country’s supervisory bodies have not regulated their application yet. Perhaps some of the responsibility for the disaster should be addressed to those ineffective supervisory bodies.
The State of Minas Gerais is an important mining region in Brazil and there are many other mining dams, increasing the concern of a second disaster in the region. Certainly, a better integrated monitoring system is going to arise from this accident and hopefully this tragedy will not be repeated.
Contributed by Ana Patricia Pacheco
Ana has just obtained her BSc in Environmental Chemistry at the University of São Paulo, Brazil. In the last academic year Ana visited the University of York, working at the Green Chemistry Centre for Excellence on alternative bio-derived solvents.