More work is needed to stop the stench that has been plaguing Central Hawke's Bay.
Since January a pong has been coming from the Waipukurau Wastewater Treatment Plant, with the Central Hawke's Bay District Council putting a number of measures in place to mitigate the stench.
There had been some success but last month the smell returned. So the council is now installing new equipment at the plant, and investigating how appropriately the district's two treatment systems are able to meet resource consent requirements.
Central Hawke's Bay District Council chief executive Monique Davidson acknowledged the smell was offensive and unacceptable for properties in the neighbourhood.
"Council officers are working hard to resolve the problem. Our initial efforts have partially worked. Now we have identified the need for further aeration and have purchased additional equipment," she said.
Initially the smell was due to high hydrogen sulphide levels coming to the surface of the new stormwater balancing pond from the outflow of the anaerobic pond.
"We applied a top dressing solution of sodium nitrate, and this has been partly effective at reducing the odour. Despite this, some smells are still being emitted from the anaerobic pond, so we have closed it down until a permanent solution is installed."
The additional aeration units are being installed this week. Of concern to council was that the additional aeration units would not fix the ammonium levels the plant is having, which are higher than the consented allowances.
At a council meeting last week, a motion by Mayor Alex Walker was passed unanimously, that a report on the appropriateness of the Waipukurau and Waipawa wastewater treatment systems and their ability to meet resource consent requirements was presented by the end of November.
This scope needed to include all resource consent requirements for both systems, the capacity of the system to deal with residential and trade waste demands, as well as future growth projections for the district.