Central Hawke's Bay's proposed $6 million sewerage plant could be struggling to meet environmental standards set by the Hawke's Bay Regional Council.
The CHB district council voted to build a floating wetland system to upgrade the Waipukurau and Waipawa wastewater treatment plants which current discharge into the Tukituki River.
But the regional council said it had a number of "significant concerns" about the upgrade, in particular how the design of the proposal would deliver the standards required by the September 2014 deadline.
CHB provided the regional council with a report detailing the upgrade in October. The report had been reviewed by independent experts who highlighted the problems the CHB council must address.
It included the need for a management plan for the floating wetlands and a plan detailing how sludge produced at both sites would be managed.
Regional council resource manager Iain Maxwell had written to CHB council urging it to provide details of how the problems would be dealt with.
If the regional council was not satisfied with the proposal, additional conditions requiring a sludge management plan would be incorporated into the resource consent through a review in September next year.
The two councils were at odds over how best to treat wastewater in Central Hawke's Bay, which started when the regional council proposed a scheme whereby treated sewage would be discharged over land used for a forestry enterprise.
But CHB council said the project's cost estimates were now over $8.5 million which was too expensive for its ratepayers.
Central Hawke's Bay mayor Peter Butler said he wanted to let the CHB council's services manager Steve Thrush look at the regional council report before making a comment.
In Mahia, the regional council reminded people to apply for replacement wastewater permits before the end of November.
Wairoa District Council was building a new community sewage scheme, which would pipe wastewater from the Mahia Beach community to oxidation ponds, to be treated and then irrigated onto regional council-owned land.
The new system was expected to be up and running by June next year, but in case the project was delayed people would have to apply for new permits "as a safety net" by the end of November.