Cr Colin Weatherall said yesterday he was ''somewhat surprised'' by the figures in a council report to be considered during the 2013-14 pre-draft annual plan meetings beginning tomorrow.
The report concluded the complex would cost $18 million, not the $11.5 million estimated by the working party last year.
That meant a more modest Moana Pool upgrade - spending $3.9 million to add a new 25m x 25m pool - was now the most cost-effective option, the report said.
However, pressure on parking at Moana Pool also needed to be addressed. One option was to convert council-owned Roberts Park football field, located above the pool, into a parking space for 150 vehicles, at a cost of nearly $1 million, the report said.
Another option would be to realign existing pool parking, creating an extra 70 spaces, at a cost of $300,000.
The introduction of parking charges should also be investigated. The report by council survey administrator Anne Gray was the latest step in a long-running review of the city's aquatic facilities which began in 2010.
The working party last year identified a $11.5 million swimming complex at Mosgiel as the best option to pursue in ''three to five years'', followed by a $13.2 million upgrade of Moana Pool in 10-15 years.
The cost of the Moana Pool option included a new lane pool and a $8 million car-parking building.
Councillors last year decided to delay any decision for a year, allowing staff more time to investigate the options.
That led to the latest report, made public this week, in which all trace of a $13.2 million upgrade of Moana Pool had disappeared.
Instead, the report said adding a new 25m pool at Moana Pool would ''address most of the capacity constraints'', catering for an extra 100,000 visitors each year, and be the most cost-effective option.
However, it would not address problems at Mosgiel's existing pool and would require the relocation of the Moana Pool hydroslide.
The estimated $3.9 million cost involved would cover removal of the hydroslide, but not reassembling it in a new location, the report added.
Four options for Mosgiel were also canvassed, ranging from doing nothing, which would still cost $1.1 million in maintenance over 10 years, to the new $18 million complex.
Option two would mean $2.25 million spent improving heating, insulation and changing room facilities to allow year-round use of the existing Mosgiel pool.
Option three would result in $5.9 million spent building a 25 x 25m pool, open year-round, on a new site in Mosgiel.
However, those options would not sufficiently address space shortages and likely future demand issues within Mosgiel, the report concluded.
An $18 million complex would, and ''into the distant future'', but would also have the greatest impact on rates and would not address problems at Moana Pool, the report said.
The Mosgiel complex, if built, would include three pools, a leisure pool, spa and sauna, built on a new site, requiring extra staff and catering for up to 75,000 extra visitors each year.
Cr Weatherall said yesterday the working party had not had any input on the report, and ''it would be fair to expect some questions'' during the budget meetings. He was at a loss to explain the large increase in the estimated cost of a new Mosgiel pool, or the more modest $3.9 million price tag now attached to a Moana Pool upgrade.
The staff report said a review of the working party's results had ''identified a number of potential errors and discrepancies that needed to be resolved''.
Council operations general manager Tony Avery said the estimated cost of the Mosgiel complex had been increased after staff examined the costs involved in other pools built recently in New Zealand, including Timaru.
The cost of upgrading Moana Pool had dropped mainly because plans for a parking building ''just can't be justified'' and had been axed, he said.
However, the updated figures did not include the cost of land acquisition and resource consent costs, where required, the report said.
It would be considered during 2013-14 pre-draft annual plan discussions beginning tomorrow.
