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Details of a new power scheme on the Waitaki River and how it would operate with the Waitaki dam were outlined in the Environment Court yesterday by the Meridian Energy.
The north bank tunnel concept scheme is the culmination of investigations since the late 1970s into using the lower river for more electricity generation.
That included Meridian's Project Aqua power scheme, a 60km power canal on the south side of the river between Kurow and almost to State Highway 1. Meridian cancelled that in 2004.
Meridian infrastructure development manager Nick Eldred said the north bank tunnel concept was one of a number of alternatives Meridian investigated after Project Aqua.
The new scheme would be operated as an integral part of the existing Waitaki system, which represents about 30% of New Zealand's generation.
To make the scheme viable, Meridian needed up to 260cumecs from the river, leaving monthly minimum variable flows of between 110 and 150cumecs.
That would generate up to 1675GWh a year in electricity, releasing a net 1100 to 1400GWh on to the market after deducting the generation lost at the Waitaki dam.
Mr Eldred said Waitaki produced about 500GWh a year, which would decrease to about 225GWh with the tunnel scheme.
The net gain from the scheme would amount to enough electricity for all homes in Christchurch.
Conditions on consents primarily covered in-stream effects, but also reflected the potential social effects and management and recreation gains, Mr Eldred said.
Camilla Owen, counsel for the Lower Waitaki River Management Society, which is appealing the scheme, asked Mr Eldred if the society could be included as part of both the consultative liaison group and another community group which was to prepare a recreation management plan with $1 million funding from Meridian.
Mr Eldred said the society, which had always opposed the scheme, had not been included "probably because it has not asked".
Participants in the group preparing the recreation plan had not been named because that would be established by the community itself.
"We have deliberately left that [membership] open because it will be driven largely by the community."
North bank tunnel Hearings: Day 6
• The Meridian Energy Ltd north bank tunnel concept power scheme, costing up to $993 million, is to take up to 260cumecs of water from Lake Waitaki into a 34km tunnel between the Waitaki dam and Stonewall, with one powerhouse generating between 1100 and 1400GWh a year.
• Environment Court hearing June 22 to July 3, Oamaru; July 6 to 10, Christchurch.
• Hearing before Judge Jon Jackson, commissioners Dr Alex Sutherland and Helen Beaumont and deputy commissioner Ken Fletcher.
• Evidence yesterday: The scheme proposal, relationship to the Waitaki dam, flow regime, planning including consent conditions and regional plans.