Meridian plans new Waitaki scheme

Meridian Energy is investigating a fresh hydro scheme for the Waitaki River.

A tunnel-based power scheme with a single power station for the north bank of the Waitaki River, below the Waitaki Dam, could be built for $600 million to $900 million.

Meridian Energy says the cost is based on the estimates to build its now defunct Project Aqua scheme in the lower Waitaki Valley.

Details of the scheme, which would take water from Lake Waitaki into a 36km tunnel, are included in evidence filed by Meridian for the Waitaki Catchment Water Allocation Board, to be presented in Oamaru from July 25.

The tunnel would take up to 260 cumecs (cubic metres a second) of water from the lower river's average daily mean flow of 389 cumecs - about the same as Project Aqua - between the Waitaki Dam and Stone Wall.

Meridian cancelled Project Aqua in March last year. It involved a 61km power canal with six power stations along the south side of the Waitaki River, running between an intake at Kurow and an outfall just above the State Highway 1 bridge.

It was estimated to cost $1.2 billion and would have produced 530MW at a cost of about 4.5c a KW/h.

Now, it is looking at taking water from above the Waitaki Dam to an outfall at the Stone Wall next to State Highway 82 just west of Ikawai, 38km southeast of Kurow. The north-bank scheme would produce between 210MW and 260MW of power at a cost of between 5.7c and 7.5c a KW/h.

The water allocation board in its draft plan has allocated no water on the lower river for hydroelectricity generation.

Meridian hydro development project manager Tony McCormick said in the evidence the company had explored a tunnel-based concept on the north bank between the Waitaki Dam and Stone Wall. Water would be taken into the scheme by a reinforced concrete-intake structure below lake level at Waitaki Dam.

Two "base schemes" were being investigated. The first option was to build an underground power station on the north bank about 200m downstream from the Waitaki Dam.

The second option was for an underground power station in the vicinity of the Stone Wall.

Mr McCormick said even though Meridian had cancelled Project Aqua, it had always recognised the significant hydro-generation potential of the lower Waitaki River.

It was actively seeking an allocation of water for hydro generation from the board in the final plan.

- NZPA