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Pipeline across the harbour will provide alternative water supply

A $116 million project aimed at improving water supply resilience for the metropolitan region was approved yesterday at a meeting of the Greater Wellington Regional Council.

The Council approved the Cross Harbour Pipeline as the preferred project for an alternative water supply to Wellington City,

Wellington City’s water is currently piped from the Hutt Valley along State Highways 1 and 2, and crosses known earthquake fault-lines multiple times.

If damaged in a large earthquake, the pipes could take months to repair. That could leave parts of the city, particularly the eastern and southern suburbs, without water for up to 100 days.

Wellington Harbour: long pipe required to take water underwater

The new pipeline will carry water from the Waiwhetu Aquifer in Lower Hutt, through a high density polyethylene pipe nestled into the harbour floor that will come ashore in Evans Bay.

The project is currently funded for $116 million in the regional council’s 10-year plan. The next stage will be to determine the best locations for the supporting infrastructure and pipeline itself, and then finalise designs and costings.

The pipeline will also provide much needed resilience for day-to-day water operations, said Wellington Water’s general manager of design and delivery, Tonia Haskell. “We are limited with our bulk water supply options into Wellington at the moment. This pipeline will give us an alternative supply line to Wellington, in the event we need to carry out some major repairs or maintenance work on our existing pipes and reservoirs.”

The confirmation of the pipeline comes after two exploratory bores were drilled into the harbour floor showed that water quality and quantity from the aquifer closer to Wellington was not suitable for the resilience goals the councils were seeking.

“We needed the water to be available in sufficient volume to meet our expected needs,” Ms Haskell said. “Unfortunately, both bores came up a bit short in that respect. In addition, there were quality issues that meant we would have had to invest more money in treating the water from the bores. So unfortunately that option didn’t stack up.”