Up to $3.6 billion needed for water services to support capital's population growth

Tuesday, 15 June 2021

Wellington will need to build 11 new water reservoirs and a range of other water infrastructure assets to support forecast population growth over the next 30 years.

The Wellington City Council will need to spend up to $3.6 billion to upgrade and build water infrastructure to support estimated population growth over the next 30 years.

A Wellington Water report, obtained by Stuff, has revealed the extent of new water infrastructure needed to sustain up to 82,700 extra people expected to reside in Wellington City by 2050.

The upgrades are required to support the council’s draft spatial plan, which proposes to increase building height regulations across the city in order to enable more medium and high-density developments.

The projects include 11 new water reservoirs, a new water storage tank and wastewater treatment plant, widespread stormwater pipe upgrades, and four new pump stations – three for stormwater and one for wastewater.

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Up to 2242 new homes could be built in Johnsonville to support Wellington’s forecast population growth, with developments up to eight storeys high proposed in the town centre. (File photo)

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A six-storey minimum building height has been proposed for the central city, which would be expanded to take in parts of Thorndon. (File photo)

The new reservoirs and storage tanks would hold a total of than 61 million litres of water – the equivalent of more than 24 Olympic-sized swimming pools.

Upgrades will also be needed for existing wastewater treatment plants in Porirua, Moa Point, and Karori, while a fourth would also be built in Karori.

According to the proposals, which were presented to city councillors by Wellington Water last week, the upgrades would cost between about $70,000 and $520,000 per new dwelling across various suburbs.

The council needs to build up to 31,000 new homes to accommodate future growth, leading to a corresponding maximum cost of about $3.6b to provide associated drinking, waste, and stormwater services.

Building heights up to eight storeys have also been proposed for parts of Kilbirnie. (File photo)

The council has budgeted $2.7b for water pipe maintenance and upgrades over the next 10 years, as well as up to $208 million to upgrade the Moa Point wastewater treatment plant.

It could not confirm whether any of that funding would be able to cover the proposed upgrades listed in the new report.

Wellington Water said in a statement the suggested upgrades in the report were only proposals.

The council-controlled organisation had provided the council with earlier research on required upgrades associated with its growth plans, and the new report recommended further studies on the additional proposals.

The report, written in March, outlines the cost of water upgrades per new dwelling for each suburb in which development is planned.

The most expensive is Thorndon, with an average cost of about $520,000 per new housing unit. Up to 99 new dwellings will be needed there.

The cheapest is Khandallah, with an average cost per new dwelling of about $70,000, and up to 1666 new homes needed.

The areas most heavily targeted for new homes are Te Aro, with up to 6372, and the northern suburbs, with up to 6526.

Up to 2500 extra homes are also planned on greenfield sites in the northern suburbs.

Upgrade costs per dwelling for Te Aro are about $100,000, while the northern suburbs – Tawa, Churton Park, Newlands, and Johnsonville – range from about $75,000 to about $130,000.

The most expensive suburbs behind Thorndon are Mt Cook, Island Bay, Miramar, and Mt Victoria.

Councillors will discuss the report at a meeting next week.

Councillor Diane Calvert, who chairs the council’s finance and performance committee, said the information should have already been made public.

“However unpleasant and daunting, we need to get all the information – the city’s infrastructure growth needs, costs and capacity – on the table, if we have any hope in strategically planning and budgeting for the future of our city well.”

Wellington’s water wish-list

11 new water reservoirs

Miramar Peninsula – 12 million litres

Johnsonville – 10.5m

Tawa – 7.5m

Karori – 6.5m

Newtown – 6m

Island Bay – 4.5m

Newlands – 2.5m

Churton Park -2m

Kelburn – 2m

Ngaio – 1.5m

Island Bay – not specified

New water storage tank

Karori – 6 million litres

Three new stormwater pump stations

Central Wellington, Te Aro, Kilbirnie

Wastewater pump station

Te Aro

Wastewater treatment plant upgrades

Karori, Moa Point, Porirua

New wastewater treatment plant

Karori

Stormwater pipe upgrades

Tawa, Newlands, Johnsonville, Karori, Te Aro-Newtown, Kilbirnie, Island Bay