New filters lift water quality

The council's Waipawa and Waipukurau treatment plants - commissioned last year - have been discharging semi-treated water high in contaminants back into the Tukituki River. Photo / File

Central Hawke's Bay District Council says new filtering equipment at its Waipawa wastewater treatment plant is proving effective as it works to fix problems which have seen it discharge contaminated water into the Tukituki River.

The council's Waipawa and Waipukurau treatment plants - commissioned last year - have been discharging semi-treated water high in contaminants back into the river, in breach of resource consent conditions.

In January, Hawke's Bay Regional Council issued the district council with abatement notices requiring it to improve the quality of the treated wastewater so it complied with the consent conditions.

Since then the district council has been working through agreed improvement plans at the plants, which include installing filtering equipment known as lamella clarifiers at both plants.

The plants have been processing an unexpectedly high quantity of organic matter which has blocked sand filters and the lamella clarifiers are designed to address the problem.

"We've been running the lamella at Waipawa for about three weeks now and it's done exactly what we expected," district council technical services manager Steve Thrush told a meeting of the regional council's environment and services committee this week.

To illustrate the point, Mr Thrush showed councillors two sample jars, one containing brown untreated sewage and the other clear liquid processed through the Waipawa plant which he said was comparable to the drinking water in a carafe in front of him.

Councillor Peter Beaven asked Mr Thrush if he would drink the sample water.

"I wouldn't advise people to drink it although it does appear to analyse drinkable. It would be hard to tell the difference if you didn't know," Mr Thrush said.

"We expect we will have that plant working well from now on."

Two lamella filters are due to be installed at the larger Waipukurau treatment plant over the next fortnight.

Mr Thrush said given the experience engineers had gained from the installation and early operation of the Waipawa filter "we should be able to produce results very quickly".

As part of the compliance process, the district council must provide the regional council with independent reports on the results of the installation of the filters.

The Waipawa report is due by July 8 and the Waipukurau report by August 19.