The Gualaxo do Norte River, in Mariana (MG), was the first spring reached by the tailings of the Fundão dam, which fail on November 5, 2015. The tailings would cover 670 kilometers, crossing Minas Gerais and Espírito Santo municipalities until reach the sea, 16 days later. The environmental disaster is considered one of the largest in the country and left 19 people dead and 3 districts destroyed in Minas Gerais – Bento Rodrigues and Paracatu de Baixo in Mariana, and Gesteira in Barra Longa.
An important tributary of the Doce river, the Gualaxo do Norte River was 48 of its 60 kilometers long, affected by tailings from the Fundão dam. The watercourse is part of an 80-kilometer path that was the first and most affected by the 39.2 million cubic meters of tailings released by the failure. The tailings entered the Santarém stream and then reached the Gualaxo. It arrived at the Carmo River and went to the Risoleta Neves Hydroelectric Power Plant (known as Candonga). The plant’s reservoir has dammed about 10 million cubic meters of tailings, a quarter of all that leaked from Fundão. Another 20 million cubic meters traveled the Doce River and part of them reached the mouth in Regência, in the district of Linhares, Espírito Santo State.
Repair actions on the river began shortly after the event, still in 2015, with the cleaning of the riverbeds and stabilization of the banks of the Gualaxo and Carmo River, between Mariana and Santa Cruz do Escalvado, in Minas Gerais. More than 150,000 cubic meters of tailings were removed from the center of Barra Longa (the only municipality that had its urban area reached by the tailings). From Candonga, until June 2019, 959,000 cubic meters of tailings were deposited in a 400-meter path closer to the dam. The cleaning of the reservoir is a complex operation that began in 2016. To contain the tailings slurry that could still arrive from Fundão, three metal dam were built inside the reservoir of the plant, where they will be submerged after filling this structure.
To combat erosion and prevent tailings accumulated on the outside of rivers from falling into their riverbeds, 800 hectares of fast-growing native species were planted. At the same time, erosion control and bank overhaul actions were carried out over an area of approximately 1,522 hectares – the equivalent of 1,500 soccer fields.
Reshaping is a technique used to stabilize riverbanks through revegetation. This avoids the erosion process, which can cause water turbidity to increase when moving the tailings, yet modify its natural course.
The technique also contributes to give natural regeneration capacity to the area. With the increased vegetation on the banks and improved water quality, conditions are created for an environment with more aquatic and terrestrial biodiversity.
After the beginning of emergency vegetation planting and riverbank reforming, the process of recomposing riparian forest with native tree species began in January 2018. The goal is to provide the return of native fauna and microorganisms. These species are adapted to local conditions and are ideal for controlling the velocity of rainfall runoff, as well as filtering and absorbing sediments, preventing them from falling into the river channels.
Restoring riparian forest is fundamental to the health of the Doce River basin and, of course, to water quality. According to the NGO WWF-Brazil, “riparian forest is all kind of native vegetation that is on the banks of rivers, streams, lakes, water eyes and dams. The word “ciliary” alludes to the importance that the eyelashes have for our eyes. The same can be said about the protection of rivers and lakes: it prevents siltation and acts directly on the physical conservation of rivers. In addition, by providing food and shelter for wildlife species, it also contributes to the conservation of biodiversity.
This riparian forest restoration work is expected to continue until March 2020 in Permanent Preservation Areas (PPAs).
Gualaxo do Norte River, which suffered the first environmental impact, already responds to actions taken by the Renova Foundation. The results of water quality monitoring show that turbidity is declining each year, compared with the end of 2015, immediately after the rupture, when turbidity was at its peak. In the last dry period, which runs from May to September, daily turbidity rates remained within the limits set by the Brazilian Ministry of Health and the State Council for Environmental Policy (Copam) 90% of the time.
The daily turbidity rates of the Doce River and its tributaries Gualaxo do Norte and Carmo remained within the limit of the legislation 90% of the time.
Currently, two projects to recover Gualaxo River are underway. The actions are part of the Renova Foundation’s Tailings Management Program, which aims to find the best solutions for dealing with Fundão tailings. Initiatives vary according to the conditions of each area (the plan divided the length of the Doce River into 17 areas) and are always designed to have the least impact on communities and the environment. “Each area has a specific tailings treatment solution. In the case of the Gualaxo River region, it was decided, together with the Tailings Management and Environmental Safety Technical Chamber, not to remove the tailings and create conditions for environmental self-recovery,” says Pedro Ivo Diogenes, socio-environmental expert of the Management Program.
The Technical Chamber for Tailings Management and Environmental Safety (CT-GRSA) monitors Renova Foundation initiatives such as tailings management, construction of containment systems, preparation for environmental emergencies, recovery and resumption of the Risoleta Neves (Candonga) Hydroelectric Power Plant and treatment of impacted rivers.
Pedro Ivo Diógenis
MANAGEMENT PROGRAM SPECIALIST COMMENTS SOLUTIONS ADOPTED (in portuguese)
Environmental self-healing does not mean letting nature take care of everything on its own. It is necessary to combine time, studies, research and technology. One of the projects implemented by the Renova Foundation on the Gualaxo River is the Gualaxo riverbed renaturation, which began in May 2019, still as a pilot, between the Camargo and Santarém streams. The technique is a pioneer in Brazil and aims to give the source the natural conditions for its recovery, recomposing its biodiversity and becoming, once again, habitat for native species.
Renaturation consists of positioning natural elements, such as logs, roots and branches, strategically in the river, to regulate water velocity and reproduce natural characteristics of the aquatic environment, such as fish hatcheries. The locations where the technique is being applied were mapped based on a detailed survey of river characteristics.
“The trunks are fixed to the river bank and channel. In this way they create habitat areas for fish and improve the quality of the sediment,” explains Pedro Ivo Diogenis.
In just three months (between May and July), the pilot project set, on a area of approximately 1,800 meters along the Gualaxo do Norte River course, 79 trees, 103 submerged logs and 23 bundles of grass.
The central concept of renaturation is to provide physical conditions for the restoration of biota and to create refuges for these organisms. “The branches themselves act as a shelter by retaining leaves and organic matter. Smaller organisms, which are the basis of the food chain, have a favorable environment. Some physical results are immediate, such as the sedimentation of the trunks, ideal for attracting fish. The return of biodiversity should have more significant results between six months and a year,” says Fernando Aquinoga, technical director of Aplysia, an environmental services company responsible for Gualaxo’s renaturation work.
APLYSIA TECHNICAL DIRECTOR COMES ON BIODIVERSITY RETURN PLAY ( IN PORTUGUESE)
With the progress of the project, some parts of Gualaxo have gradually changed. “It is an extremely important process. Renaturation means going back to the natural, in other words. And this is exactly what we are doing with Gualaxo stretches: bringing them back to life, seeking that aquatic heterogeneity that existed in the water before the Fundão dam failure,” says the leader of the Tailings Management and Water Monitoring programs. Renova Foundation, Juliana Bedoya.
“We are bringing Gualaxo back to life, seeking that aquatic heterogeneity that existed in the waters before the Fundão dam rupture”
JULIANA BEDOYA, RENOVA FOUNDATION
Another project aimed at Gualaxo that improves the quality of the water that reaches the Doce River is the Natural Treatment Station (NTS). This action uses technological solutions to achieve a better standard of water quality. Through the Renova Foundation’s Economy and Innovation Program, the project is being developed by LiaMarinha, a Mariana startup selected by the Industry Innovation Notice, an initiative of the Renova Foundation in partnership with the Brazilian Micro and Small Business Enterprises Support Service (Sebrae) and the National Service for Industrial Learning (Senai). The company receives funds from the Foundation to conduct the project.
NTS uses filter barriers and islands of vegetation in the river channel. These barriers are able to filter water and absorb metals. With the sediment retained, the water that follows will reach the river in higher quality with a lower turbidity index. The station is being deployed and early results related to water and biodiversity are expected in February 2020. For the assessment of the effectiveness of the methodology, data will be compared with those from the period prior to its use.
Several parameters are being monitored before and after the implementation of the two projects, such as sediment quality, water, benthic (communities of organisms living deep in aquatic environments), fish, tailings thickness, among others. The idea is to expand the techniques that present good results to other parts of the river.
ACTIONS IN PROGRESS
Forest revegetation project, with the planting of native species along the Gualaxo do Norte River to Candonga
Forest restoration of PPAs on rural properties in order to resume agricultural activities
Gualaxo renaturation with natural elements, with the installation of trunks, roots, to create favorable conditions for biota
NTSs use filter barriers and islands of vegetation to retain sediment and absorb metals, an action that improves water quality.
ENGAGEMENT OF RURAL OWNERS
Rural producers play a key role in the recovery challenge of the Doce River basin. According to The Nature Conservancy (TNC), the world’s largest environmental organization, deforestation, poor agricultural practices and other land uses have led to moderate to high degradation in 40% of the world’s urban watersheds. Therefore, it is essential that initiatives for the recovery of degraded areas involve the landowners.
This is what the Renova Foundation’s Sustainable Land Use (UST) front is doing: it works to promote the engagement and awareness of rural producers, encouraging them to apply techniques that ensure the resumption of their activities based on environmental conservation practices. As such, they have been protagonists in sustainable production processes, with positive impacts on improving water quality and the environment, indicating a better future for the Doce River basin.
Rural properties reached by the Fundão dam failure, located between Mariana and the Risoleta Neves Hydroelectric Power Plant (Candonga), are turning into production units with sustainable management. The actions are developed in 235 properties. Among them, 21 were selected as model units.
About 230 rural properties are receiving actions to promote the resumption of their agricultural activities and environmental recovery
The expansion of agro-ecological experiences generates diversification of production, learning in property management, rational management of agricultural production and conservation of natural resources such as soil and water.
Producers adopt low carbon or carbon capture technologies with the support of regulators and environmental services in productive or conservation areas. The recovery of 594 hectares of impacted rural productive areas is expected. Another 2,559 hectares located in non-impacted regions (four times the size of tailings sites) will be requalified, expanding the region’s economic and environmental sustainability chain.
So far, the Renova Foundation has implemented 248 “barraginhas” (dams for rainwater harvesting) and 10 hectares of paddocks for sustainable livestock management on rural properties. In addition, through the Forest Operations front, Renova implemented equipment such as chicken coops and corrals, repaired damaged irrigation systems, fenced, soil corrected, fertilized and planted.
“We are rebuilding. Difficulties appear, but little by little we solve them”
WALDIR POLLACK, RURAL OWNER
Improvement in water quality supports the agricultural production of these properties, such as that of farmer Waldir Pollack, who owns land near the community of Paracatu de Baixo – Mariana district (MG) – and saw the tailings encroach on his property. In an interview with Brazil Agency, Pollack says he produces about 40 varieties of food. Most of the products, which do not carry pesticides, are sold at weekly fairs in the urban area of Mariana. “We have not yet reached the potential we need, but we are growing every day. We are rebuilding. The difficulties appear, but little by little we solve them,” he says.