On 20 June, contractor the Campos Novos Supplier Consortium, CFCN, with concession owner Enercan, confirmed that the recently completed Campos Novos dam in southern Brazil had failed due to a leaking diversion tunnel, releasing all of the water impounded in its reservoir.
The 202m high concrete faced rockfill dam has a crest length of approximately 592m. Following the uncontrolled release, which was luckily contained by another dam, aerial photographs were released by Friends of the Earth Brazil showing major cracks in the base of the dam on what should have been the submerged side.
On 2 July, Enercan said a visit by the Commission of Mines and Energy and other officials had confirmed that the dam structure was sound. Politician Mauro Steps represented the Commission on the visit and proclaimed: “The problem in Campos Novos is only the delay in power generation, there is not any structural problem in the dam, it is solid.” He added that reports in the media were scaremongering, saying it was only the face of the waterproofing concrete that had cracked.
Impounding of the reservoir began in October 2005. When it reached 80% capacity, one of the diversion tunnels was partially flooded and at this point some leakage through one of the gate structures was observed.
Despite mitigating efforts, the outflow on 19 June drained the reservoir. As the entire outflow occurred through the diversion tunnel, none of the other structures associated with the facility were affected. By 24 July, CFCN announced it had begun remedial work on the diversion tunnels. Diversion plugs in tunnel 1 will be removed to allow the river to flow through while diversion tunnel 2, currently carrying the flow, is sealed with concrete plugs. When this is finished, after 150 days, the tunnel 1 gates will be lowered for filling.
