ABSTRACT
In Scandinavia and worldwide, tunnels are largely used to transport water in many industries and municipal activities, e.g. hydro and nuclear power, water transport for drinking and wastewater, raw water supply to industrial facilities, etc. These tunnels are usually constantly filled with water but need monitoring and maintenance inspections at regular intervals.
The strategic management plans must indicate the risks and plan for mitigating actions to secure continuous operations and long-term safety. An accident can cause a long rehabilitation time and associate high costs as well as production break which can become more costly than rehabilitation itself.
The minimum effect on operations of a facility can be achieved by performing inspection and maintenance with a ROV (Remotely operated vehicle) equipped with sonar, cameras and measuring instruments and tools without dewatering and under safe working conditions.
