Gisborne treatment plant a 'must-have' despite ballooning cost

4:04 pm on 15 May 2020

Those managing Gisborne city's wastewater treatment plant upgrade faced a grilling yesterday from district councillors seeking answers over the project's multimillion-dollar budget blow-out.

Gisborne district councillors unanimously agreed to commit $33.5m to a wastewater treatment plant upgrade when they met via Zoom yesterday

Gisborne district councillors unanimously agreed to commit $33.5m to a wastewater treatment plant upgrade when they met via Zoom yesterday. Photo: Screenshot / Zoom

In an exhaustive two-hour debate, councillors wanted to know how the estimated project cost had jumped by more than $9 million from a budget of $24.4m based on a 2016 concept design.

But in the end they unanimously agreed to incorporate the larger budget of $33.5m in the council's upcoming 2021-31 Long Term Plan.

"This is critical, essential infrastructure for our city - we must have it," councillor Amber Dunn said.

The plant's upgrade will mean the city's wastewater is clarified and disinfected before being pumped out to sea.

The additional treatment is a resource consent requirement with a December 2020 deadline.

The upgrade is not due to be commissioned until March 2022, so the council will need to apply for an extension.

Councillor Meredith Akuhata-Brown said wastewater improvements needed to be prioritised.

"Most of our community ... simply want to see no more tūtae (faeces) in the bay and rivers," she said. "It's a very basic ask."

Deputy mayor Josh Wharehinga said the budget blow-out was a reason in itself for the council to get a move on with the upgrade.

"That's why pies no longer cost 50c ... everything increases with time."

Indeed, there are no guarantees that even $33.5m will be enough.

With the new budget still based on a preliminary design, Gisborne District Council chief executive Nedine Thatcher Swann said the project could end up costing 15-20 percent more.

"This is not like a roading construction project where you know exactly how much it's going to cost - where there's a high degree of certainty and low degree of risk," Thatcher Swann said.

Beca engineer Garry Macdonald, a member of the project team, said the $33.5m budget was a middle ground but costs may increase due to the exchange rate and a potential post-Covid boom that could drive up the price of materials and construction.

A final design for the upgrade is due by October and will be priced up ahead of the tendering process, providing the most accurate estimate of the project's cost, Macdonald said.

With councillors endorsing the increased budget yesterday, the project team will be able to progress contracts to purchase several pieces of equipment for the plant upgrade, including the clarifier and UV lamps for disinfection.

The equipment is expected to cost $5.25 million all up, although the initial outlay will be for a 5-10 percent deposit to lock in prices and ensure the items are manufactured in time for the upgrade to be completed by March 2022.

What blew the budget?

Additional costs identified in the preliminary design include:

  • Filters required for clarification: $3.5m
  • Increased provisional and general costs: $3m
  • More UV equipment for disinfection: $1.5m
  • Shifting the project site to a vacant lot adjacent to (rather than attached to) the main treatment plant on Banks Street: $1.5m
  • Enclosing dewatering equipment to minimise odour: $1.3m
  • Increased allowance for cost overruns: $1m
  • Disposal facility for septic tank waste: $0.8m
  • Work to enable wastewater to be recycled for treatment processes: $0.5m

Refinements to the design, including a more condensed layout, helped pare back the total increase to $9.1m.

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