Frustration as Waipukurau wastewater plant stench returns

SMELLY: The CHB District Council is still grappling to get to the bottom of what's causing the issues at the Waipukurau wastewater treatment plant. PHOTO / File

After a brief hiatus, Waipukurau's wastewater treatment plant is again emitting offensive odours, prompting further complaints from residents and putting renewed pressure on the Central Hawke's Bay District Council to find a solution.

Mitigation measures for the smell that had been emanating on and off since last summer such as planting, odour suppressants, cleaning pipework and ongoing monitoring had been undertaken since June this year.

There had been some success but this month the stench resumed, and following advice from experts a helicopter was brought in this week to top-dress the area with calcium ammonium nitrate.

This also proved ineffective, a result that had disappointed the council, said CHB mayor Alex Walker.

She said she appreciated the community's patience was wearing thin and while the elected members wanted to understand the problem and focus on a solution, the plant had a long and complex history.

"We are dealing with a string of decisions and information about this plant which we need to unravel and it is taking some time."

Chief executive Monique Davidson said the situation was unacceptable and the council was continuing to work hard to resolve the issue.

"With the advice we have been receiving and actions we had been taking we were confident we were solving the problem but a couple of weeks ago complaints started coming in again - now it's almost as if the plant is rejecting the solutions."

She iterated the mayor's comments that this was not just an issue from the last seven months, that the plant had been causing concerns for many years.

The council decided on the WaterClean Technologies floating wetlands for both Waipawa and Waipukurau in 2012, and the Waipukurau plant was constructed in September 2013.

Since that time there had been ongoing issues with compliance for both plants, but only Waipukurau had issues with odour.

Initially commissioned for $6 million, the overall cost for the floating wetland treatment systems by March this year had reached $8m - $2.8m for Waipawa, and $5.2m at Waipukurau.

The Waipukurau cost had increased due to the decision to build a stormwater and balancing pond, alongside an anaerobic pond, at a cost of $1.6m.

At the time technical service manager Steve Thrush said this was in line with the budget that was set at from the start of $8.7m, but no money had been allowed for further capital works at either site.

Mrs Davidson said despite the extra costs dealing with the odour, including the mitigation work and consultants, the costs had not exceeded the existing renewals and capital budget associated with the Waipukurau plant.

When commissioned the plants came with a five-year guarantee from WaterClean Technologies, and she said the council was actively working with that company to ensure the plant that was purchased and its performance was assured and that the company was being held accountable.

"We are working through a process with our lawyers to ensure we either get the value out of what we paid for or that we go back to the fact we have not received what we paid for and get compensation for that."

She said information from all parties involved to date was being collated with the aim to put forward recommendations on the way forward by early November.

"We are seeking advice from the best in the business of wastewater treatment plants. I do not want bandaids for this - I want a long-term solution."