At around 11 p.m., during a transfer operation, nearly 100 m³ of effluent at pH 1.1, loaded with hydrochloric acid and metals, leaked into a metallurgical plant. The release flowed into a river causing its complete acidification (pH below 3) and killed more than a thousand fish. The leak was detected only the following day at 1:30 p.m. and was stopped at 2 p.m. Fishing and swimming were prohibited. Following a visit by the Classified Facilities Inspection Authorities and the elected officials, the factory was temporarily shut down. Residents began expressing their dissatisfaction with this new release, resulting in pollution similar to that which occurred in 2009.

A rain alert required that an isolated transfer system is used for operations without sufficient prior verification before it was put back into service. The system was in fact partially open following the removal of a valve and the operator’s routine patrol during the shift change did not allow the leak to be detected.