In a short statement last week, WDC confirmed the resolution of proceedings between the parties which it did not name.
The High Court registry could only say the matter was between the council, Cook Costello and "others".
"The terms of the resolution are confidential as between the parties and the Whangarei District Council believes the resolution will ensure the integrity of the assets that were the subject of the proceedings in the Marsden City development,'' the council statement said.
"Inspections and works have a commencement date of 1/2/18 with works to be completed by 31/5/19," it said.
WDC refused to make any other comment on the matter.
Early last year, WDC said an extra $40,000 was to be spent replacing the 25 manholes at the botched development south of Whangarei after contractors discovered more problems while repairing the subsiding systems.
A report into the contract, presented to the WDC infrastructure committee, said the contract value had already increased by $100,000, but this had been "insufficient to deal with the extent of the issues which have developed as the contract has progressed".
The major work contributing to the overspend included the installation of the PE (polyethylene) manholes and repairing damage discovered during manhole exposure.
Other work included the formation of concrete collars around all PE/concrete connections to ensure the connection was robust and sealed, which also required additional pumping of ground water.
Contractors also found holes which needed additional excavation, backfilling and sealing.
On top of that, stub flanges in the weirs of the PE manholes would be installed to allow the stormwater system to be emptied for future inspections, and grates were needed under manhole lids for health and safety reasons.
