Build cut for Masterton treatment plant

COST BUMP: The Homebush sewage treatment plant is the council's largest single project and one of the most important.

It has now been discovered about 15 per cent of the planned irrigation area at Masterton's new wastewater treatment plant at Homebush cannot be built "cost effectively", according to Masterton District Council.

In a news release yesterday, council claimed groundwater levels in the vicinity of the old pond were found to be higher than anticipated when decommissioning of the old ponds was done.

It has now been established that mitigation options, such as cut-off drains and backfilling could likewise not be done in a cost-effective way.

The upshot of the latest findings is that the council will next summer complete irrigation work in the areas not affected by excess groundwater, while looking at other options for "further removing treated effluent discharges from the river".

These will include:

Installing a Fonterra-standard irrigation water plant.

Expanding the existing irrigation zones on council-owned land.

Installing a wetland treatment system in the location of the old ponds.

Chief executive Pim Borren said Homebush was the largest single project the council had invested in and one of the most important.

"The project is nearing completion and is meeting the current needs of Masterton. It remains within budget, with $1.2 million of the $30 million construction contract with Hoppers unspent.

"We have recently confirmed that some of the irrigation areas cannot be built as planned, and will look at further long-term options while construction has ceased during the winter period."

He said without the additional areas, council was still able to fulfil consent requirements, but will be left with a 15 per cent spare capacity, rather than the planned 30 per cent contingency. "We are working on a solution which will enable us to exceed the standards required by the consent."

Mr Borren said talks were being held with Greater Wellington Regional Council and both parties were "committed to working together to produce the best possible outcomes, economically and environmentally

"We will also be meeting with other stakeholder groups such as Sustainable Wairarapa and the two iwi, as part of our option evaluation process.

"It is important that we all work together on this project in an open and transparent way. It is my role to ensure that we deliver the best value for money to our ratepayers and I am confident that we will do that," Mr Borren said.