Repair works going well on Pukaki hydro canal

Most of the immediate repair work on the Pukaki hydro canal gate structure will be completed early next week and engineers say it will easily buy enough time for a longer-term fix to be completed at a later date should it prove necessary.
The Pukaki and Ohau hydro canals were drained earlier this week to allow a detailed inspection of the structure to be made, following concerns about the possible extent of erosion of its concrete construction during the 30 years it has been in operation.

Meridian Markets and Production General Manager Neal Barclay says the inspection, timed to co-incide with a scheduled outage by National Grid operator Transpower of the Cook Strait cable, found that the gate structure was in good condition.

“The engineers found no significant issues, but repairs were necessary to some of the concrete slabs which make up the gate structure and we will be able to get that done during the current outage. It may be that we will fit steel plating on the affected area at some point in the future if we continue to experience wear on the concrete, but the repairs we are making now mean there need be no rush.”

Mr Barclay says other components were found to be in excellent condition for their age with no remedial work necessary.

“We have also taken the opportunity to clear accumulated silt and gravel from the gate structure and immediately downstream. All in all, the decision to drain the canal so we can have a proper look at the gate structure has proven to be very worthwhile.”

Meridian has been working closely throughout the exercise with Fish and Game, which has removed 500-600 trout from the canals.

The 12.5km long Pukaki canal carries water from Lake Pukaki through to Ohau A power station, above Lake Ruataniwha.

The Ohau Canal is interconnected with the Pukaki Canal and carries water from Lake Ohau. The canals are designed to be dewatered and this is the third time it has been has been done during their 30 year period of operation. It is expected the canals will be back in operation by early Tuesday at the latest.
Meridian is working closely with Transpower and the industry to ensure that there is no risk of interruption to electricity supply.

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