A public exhibition last weekend formally marked the restart of the 100MW Glendoe hydroelectric plant in Scotland.
Power firm SSE stopped operating the plant in August 2009 - less than a year after it was opened - after a section of the headrace tunnel suffered a major collapse.
Since then an intricate repair job has been underway. This has involved drilling and blasting a new 605m long, 5m diameter bypass tunnel to divert water around the damaged section, which had been constructed by tunnel boring machine. A new 555m long, 6m by 5m access tunnel was also built as part of the repair programme.
The length of the bypass tunnel was initially expected to be around 900m.
But successful work to remove collapse debris form the existing headrace tunnel meant that the length of the new access tunnel could be reduced by nearly 300m.
Contractor for the repair work was a partnership between sister companies Bam Nuttall, Bam Ritchies and Wayss & Freytag.
Consultant is Jacobs, along with peer review designer Donaldsons.