Whanganui's proposed $42 million wastewater treatment plant has again been criticised by one of the city's main employers.

In a letter to councillors, Tasman Tanning has called the cost of the Cardno BTO plant a "significant risk to the region", the projected trade waste rates for it and other businesses as unaffordable, and the consultation with industry as merely "ticking the box".

This follows yesterday's Chronicle story revealing similar sentiments from Affco.

Urging Whanganui District Council to explore other options, Tasman boss Hunter Tait said: "We are not convinced that alternatives to the Cardno BTO plant have been properly considered."


Expressing frustration at "the lack of engagement of our views", Mr Tait said concerns about the affordability of the proposed plant had been raised with the trade waste advisory group but "no meaningful progress has been made".

"We have requested data from council in order to develop our own cost model without answers being provided.

"We are left with the impression that council staff have a view as to how the failed plant should be remedied and how costs should be split between trade and municipal, and that the purpose of the group is to tick the box of industry consultation."

He said the proposed plant represented a significant risk to the region, adding: "If, as we fear, the resulting trade waste charges force businesses to close or bypass the system, the burden on the general rating base will only increase.

"The projected increases in trade waste costs are not palatable, we consider the costs are unaffordable to Tasman Tanning and industry."

Referring to the October 2015 council resolution to pause and consider the question, he asked: "Is the Cardno developed design the optimum process when considering both environmental and cost-efficiency issues? We do not believe this fundamental question has been answered."