New alternative costings of the wastewater pipeline from Te Anau to Manapouri claim it would cost $6 million less than what the Southland District Council estimated last year.
The independent expert that has worked with advocacy group Fiordland Sewerage Options (FSO) has put forward his own estimates of how much sub-surface drip irrigation could cost, claiming it would be more than $6 million less than what the SDC estimated in its business case for the Kepler Option late last year.
Last week Peter Riddell of Ecogent sent a prepared report for the SDC to consider, saying some of the cost estimates the council made could be significantly reduced from the council's estimated cost of $21.8 million to $15.4 million.
The council has a consent to aerially discharge treated wastewater at the Kepler Block. However, in December the Southland District Council agreed to further investigate the cost and logistics of a more discreet underground alternative known as sub-surface drip irrigation before making a final decision.
In its 2017 business case the council estimated the consented centre-pivot option would be the least expensive option at $14.5 million. Sub-surface drip irrigation is preferred by the Te Anau Wastewater Discharge Project Committee and generally favoured by the Fiordland community at large.
According to Mr Riddell's report, the biggest cost savings could be made through reducing the size of the dispersal field, the membrane filter capacity, and the pipeline that would transport the treated wastewater from Te Anau to the so-called Kepler Block next to the Te Anau-Manapouri Airport.
FSO chairman Alistair Paton-McDonald said the costings were done pro bono by Ecogent.
SDC chief executive Steve Ruru said the council was now months past the business case stage and was now working on better refining the design and costings of the sub-surface alternative. He said Mr Riddell was using a different set of assumptions in building his estimates without understanding the council's reasons behind its own estimates.
Independent of the report, Mr Ruru has extended an invitation for Mr Riddell to provide expert comment as the council digs in on more robust costings on a sub-surface alternative. The council would also soon have an external peer reviewer on board for the project as well, he said.
Cr Ebel Kremer of Te Anau said it was important to make sure the two reports were in fact comparing the same things, but it was fantastic that Mr Riddell had provided information and that there was an opportunity for the council to use his expertise.
FSO was pleased with the council's invitation to Mr Riddell to be involved, saying it was a positive response on the council's behalf.