Alerted remotely around 8 pm by a fault alarm, the on-call technician at a hydroelectric dam was on-site at 8:25, when he noticed the partial opening of one of the dam’s check valves. The control room closure station was inoperable, and the valve continued to slowly open with a flow rate exceeding the authorization (20 m³/s measured vs. 10 m³/s allowed). After verifying the absence of personnel immediately downstream, the technician entered the utility room associated with the defective valve, where he discovered a large oil puddle stemming from a leak on the adjacent control circuit of a wall pierced by a rigid pipe. The check valve was ordered to be left in an open position while awaiting the replacement, by hoses, of the corroded pipe segments. A normal configuration was re-established on 13th June. During these works, the flow rate of a power plant at another dam upstream of this body of water was limited to 10 m³/s, and the water level was lowered, without dropping below the minimum operating height.

After this event, the dam operator scheduled replacing all existing pipes by parts made of stainless steel.