The row over a collapsed tunnel at the Glendoe hydro-electric plant in Scotland will move to the Supreme Court after the contractor appealed a court order to pay £107M in compensation.
Earlier this year Hochtief was ordered to pay SSE Generation damages over a tunnel collapse at the 100MW hydroelectric power plant in the Highlands.
The ruling came after nearly a decade of legal battles following the collapse at the plant’s main 6.2km long headrace tunnel.
The collapse happened just eight months after the tunnel had opened in 2008, and after the incident no electricity was produced at the hydroelectric plant until 2012.
A major dispute developed over whether the collapse was caused by a defect in the design or the construction of the tunnel. SSE Generation took legal action against contractor Hochtief over the collapse, and sought £130M in damages for repair works and loss of earnings as a result of the tunnel failure.
In 2016 the Court of Session in Edinburgh ruled that the main part of SSE’s claim had failed, although it did award the company £1M for loss of revenue. When Lord Woolman rejected SSE Generation’s claim he had described it as “founded on hindsight”.
After appealing the decision SSE Generation was awarded £107M after two out of three of the judges considering the appeal ruled in its favour.
The 6.2km headrace tunnel ran from a reservoir formed at the head of Glen Tarff. It ran through a Conagleann Fault Zone (CFZ), a scar in the earth formed by an ancient earthquake, at a depth of 260m. It was considered that rock conditions in a CFZ could be challenging to tunnel through.
The collapse took place roughly 2km from the reservoir and caused a complete blockage for 70m. A 600m long, 5m diameter bypass tunnel was built by Bam Nuttall, Bam Ritchies and Wayss & Freytag after Hochtief declined to carry out remedial works without being paid.
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