Assets and operations manager David Hopman said the figure had come "as a surprise to us, as previous reports into the site have indicated decontamination costs would run into millions of dollars".
Mr Hopman said the council welcomed the project being put on the list and would enter into the remediation talks.
But he said it would be inappropriate to raise community expectations that the project was economically viable.
"Every indication we have is to the contrary," Mr Hopman said.
He said it was important to know the old gasworks land was a restricted access site and the area was safe.
Contaminants were considered to be "in a stable state" in the soil and surface water monitoring had not shown any significant changes as a result of residual contamination.
As vacant land, the site did not pose any human health or ecological risk to anyone on the land or nearby.
Prior to determining the top 10 list, the results of an investigation given to the Environment Minister spoke of the land being "significantly contaminated".
The highest concentrations of contaminants were found in the immediate vicinity of what had been the main gas production area of 0.38ha, where lead, cyanide and benzopryene were found.
Many of the samples taken "exceeded guideline values for residential land and in some cases those for industrial and commercial use".
That flies in the face of what was stated 10 years ago, when the Occupational Health and Safety Service gave the site a clean bill of health after road construction workers there complained of nausea.
The then district council requested a safety report and was told the site did not pose health problems and could be left as it was, despite the presence of copper, chromium, arsenic, cyanide and napthalene, which were "not migrating off-site to any great degree".
Other priority sites on the top 10 list that qualify for government funding are: Prohibition Mine, Waiuta; Alexander Mine, Grey Valley; Kopeopeo Canal, Bay of Plenty; Calwell Slipway, Port Nelson; Te Mome Stream, Seaview; Miramar gasworks, Wellington; Onehunga Aquifer, Auckland; Rotowaro carbonisation plant, Waikato; Rudolf Steiner School, Christchurch.
