Dam plans at engineering design stage: Contact

Engineering design plans for hydro-electric dams on the Clutha River are being drawn up as Contact Energy considers the options for its power generation schemes.

The power generation company carried out a ground-drilling project near Luggate earlier this year to complete a round of geotechnical investigations at the four locations identified as options for hydro-electric dams.

Contact Energy hydro projects manager Neil Gillespie reiterated there was no preferred site for a possible hydro-electric scheme.

The completion of geotechnical investigations meant Contact was now at a stage of "engineering and design" for the potential hydro dam structures - alongside its ongoing consultation with affected communities, he said.

"Now that we have all the [geotechnical] information, we'll use that to look at what kind of dam might be built and what it might look like," he said.

Engineering designs would also give an indication of what costs might be involved, he said.

"The big thing for us to understand is the engineering and environmental costs. This also gives a feel for the economics, which in turn enables comparisons of whether it is viable to construct and when."

A definitive timeframe for when any engineering design plans might be completed to be put forward for community consultation remained "somewhere in the near future", Mr Gillespie said.

"Realistically, we hope to have it completed by some stage next year ... This is open to change."

In 2009, Contact dusted off decades-old plans for Clutha River hydro-electric schemes, deciding to revisit options for potential dams at Luggate, Queensberry, Beaumont and Tuapeka Mouth.

The company has spent the past two years investigating its options at the four potential dam sites and consulting communities, amid opposition from Clutha River protectionist groups.

Mr Gillespie said there was "not a huge team" working on the project.

An "in-house" team of three people was involved with an overview of the project, while external consultants were contracted "as required".

"My focus and the most important part of this project is picking up on the community side of feedback to ensure we can understand those views," he said.

An engineering and design perspective was about assessing the merits of the four options. He declined to specify what ground conditions the geotechnical investigation at Luggate had revealed and whether these were similar to those at other sites.

There were geotechnical "commonalities" at all four sites, which enabled the design team to work "across the options" at each respective location, given the signalled engineering plans for the different hydro dam schemes.