Further doubts raised over CHB wastewater plants

The new anaerobic pond at the Waipukurau wastewater treatment plant has been shut down because it is contributing to a bad odour at the plant. Photo supplied

Serious concerns have been raised in the initial findings of an independent review of the Waipukurau and Waipawa wastewater treatment plants, indicating neither plant was likely to be able to meet all the requirements of their resource consents.

The Central Hawke's Bay District Council ordered the review in September, following ongoing odour issues at the Waipukurau plant and breaches of resource conditions for ammonia levels at both plants, which had floating wetland systems installed in 2014.

The plants were still under warranty and the council was now in confidential discussions with the company that built them, Waterclean Technologies. Up until recently the Waipawa plant was used as a case study on the company's website, but in the past week that had been removed.

CHB mayor Alex Walker said that although concerned by the preliminary results, the council hoped that now the issues were being clarified, appropriate solutions could be put in place.

"Performance of the plants has been under question by councillors and community for several years and we are starting to get some clear answers. We now have something to work with but there is some irony in the fact that we have some of the most rigorously treated wastewater in the country but are still unable to meet all resource consent conditions. The quality of our wastewater discharge now is vastly improved on five years ago."

The final report was due to be presented to the council at the end of November, but until then it was too early to say if the plants would need to be replaced.

Upgrades to both systems in 2013 and 2014, costing $6.4 million, were completed to meet resource consent expectations to improve river conditions, and were currently complying with consents for biochemical oxygen demand, suspended solids, pH, E. coli, and phosphorus.

Issues with storm-water infiltration into the wastewater networks, however, had at times caused E. coli level breaches, and in March this year the council was convicted over its Waipawa plant.

With breaches occurring because of stormwater infiltration, an additional pond was built at Waipukurau to address the overloading, which along with a new anaerobic pond had cost $1.6 million.

After only a few months of operating, however, the anaerobic pond was shut down last month because it was adding to a powerful stench that had plagued Waipukurau residents for at least the past year.

Council chief executive Monique Davidson said the situation was more than disappointing.

"We will work with all agencies, including the regional council and central government to ensure that Central Hawke's Bay has a long-term sustainable solution, one that will allow for growth in the district as well as improved environmental outcomes," she said.

The independent review, being carried out by The Wastewater Specialists Ltd, would cover the capacity of both systems to deal with current and future residential and trade waste demands, as well as future growth projections for the district, and potential solutions and options.

Mrs Davidson said the report due in November would cost between $10,000 and $20,000 funded from operational budgets.

This report would not cover off the odour issue at Waipukurau, which remained a priority for the council to fix, and which needed more work to be done.