Samarco Mineração S.A.

The collapse of a tailings dam in Minas Gerais state, Brazil, in November 2015, caused widespread damage to downstream rivers in the Rio Doce watershed as far as the Atlantic Ocean, 600 km away. The main areas of morphological damage were concentrated in the reaches of the Rio Gualaxo do Norte, Rio do Carmo, and Rio Doce between Samarco’s mine site and the UHE Risoleta Neves hydroelectric facility, some 100 km downstream. Both the mainstem rivers and about 100 tributaries experienced damage that included scour of natural materials and deposition of dam outwash materials.

Before joining Water Street Engineering, Allan Bronsro was the technical leader of the river restoration effort in this large impacted area. Now, he provides high-level advice and assistance to Golder Associates, the lead consultant. As the river engineering projects near completion (scheduled mid-2017), it is apparent they have been remarkably successful in reducing silt inputs to the Rio Doce system.

Images:

1.     Deposited tailings and destroyed houses in the village of Paracatu de Baixo.

2.     Rio Gualaxo do Norte showing damage from both scour and deposition.

3.     Tributary rehabilitation project under construction.

4.     Water running clear in a tributary immediately after initial construction.

5.     Tributary after successful regrowth approximately one year after construction.

Allan has been involved with river engineering and emergency response to floods and debris flows since 1995.

     

    The project included:

    • rapid assessment of damage, and development of initial recovery plan (December 2015)
    • development of 'template' designs for tributary rehabilitation and armouring (January 2016)
    • construction of tributary works (February 2016 to scheduled completion in July 2017)
    • HEC-RAS modelling of the mainstem rivers, and development of 'template' designs: bank armouring where required, and sediment and erosion control on floodplains (September 2016)
    • construction of mainstem works (October 2016 to scheduled completion in August 2017)
    • various specialized projects such as protection of pipeline crossings, flood mitigation in urban areas, and advice on tailings management
    • design and initial implementation of monitoring programs (ongoing)

    Areas of Expertise:

    • Rapid damage assessment
    • Technical leadership and mentoring of Brazilian team, including design, construction field reviews, and safety
    • River engineering design

    Year:     2015-7

    Location: Mariana, Minas Gerais state, Brazil

    Client:  Samarco Mineração S.A. and Golder Associates