The Journal understands councillors were shocked when informed of the potential rate rise in the June 2010-11 budget, a move that could also delay or prevent capital works projects.

Some councillors are reportedly concerned about how residents would receive - and afford - a large rise, particularly with home interest rates on the rise.

A senior officer at the confidential briefing reportedly said a 10per cent increase was on the cards, but that figure might spiral to 15per cent if the State Government refused requests to help fund the $77million cost of remediating the former Stevensons Road landfill.

A 15per cent rise would not include compensation for Brookland Greens residents if they succeed in their class action against the council.

Casey has insisted it relied on the opinion of experts and will strongly contest the legal action.

Figures circulated at a council meeting last Tuesday showed Casey's 2009-10 budget was expected to soon slip into a deficit of $54,774. The deficit becomes $15.513million, when the above-budget costs for the 'Stevensons Road Closed Landfill escalation' are included.

A source close to the council said councillors were not guilty of mismanagement.

"The problem is almost all due to the landfill issue. The global financial crisis has also reduced interest available to the council on its investments," the source said.