He said technical and operational measures to solve the odour issue and longer-term design solutions to the plant's problems, remained the WDC's responsibility while Horizons continued to act as the regulatory authority.
"None of the actions asked of the district council will be unreasonable. We're eager to get these issues resolved with minimal cost to ratepayers," Dr Peet said.
The district council has indicated odour problems will need a long-term solution and the enforcement order covers both short-term mitigation planning and longer-term planning to finally design a solution.
He said it was hoped that after next week's discussions both councils would be able to go to the Environment Court to seek an order by consent, which could be achieved quicker than one that was opposed. Dr Peet said if that was the case the judge's decision would likely be made in chambers without the need for a formal hearing.
Wanganui Mayor Annette Main said her council generally agreed with the content of an enforcement order.
She said district council staff had worked through the content of the proposed order with Horizons staff and agreed on time frames that were acceptable to both councils.
"However, there are still some details to be worked through and, as a result, we will be seeking further discussion or mediation on some aspects of the enforcement order," she said.
She said most of the requirements in the order were covering measures the district council had already put in place or that it was intending to introduce to manage the odour issue in the short to medium term.
"In the longer term, we need to determine a cost-effective solution and we need to make sure we get it right," Ms Main said.
"Our two councils have been working closely together and this will continue as we seek to resolve the treatment plant problems."
Meanwhile, Mark Hughes, WDC infrastructure manager, said on Monday a new aerator would be installed in the main pond.
Mr Hughes said it was a large fine-air bubble diffuser that had been designed and built by council staff.
"We will also be removing some of the old aerators from the pond. We'll use the pontoons from these aerators on the new aerators we have ordered," he said.
New turbo-jet aerators were due to arrive soon after Easter.
Parts for a new atomiser fence had been ordered and had started arriving and preparatory work would be done for the new fence next week.
"This will be a high-pressure system which will help to neutralise the odour by spraying a fine mist into the air around the treatment plant," he said.
