Cost, delay and risks are too high to consider any waste management alternatives other than an incinerator for the county, Cornwall Cabinet has concluded.
In August, an extraordinary meeting of the environment and economy overview and scrutiny committee ruled the Cabinet had not properly considered an alternative to a planned £117 million incinerator scheme.
The authority decided in July not to explore the option of using alternative technology to dispose of the county's waste.
The proposal had been put forward by the Cornwall Waste Forum St Dennis Branch (CWFSDB).
The branch had argued that an alternative to the incinerator, which would burn 240,000 tonnes of waste a year, could save the taxpayer £10 million annually.
But the cabinet has stuck to its original decision insisting the incinerator must go forward.
Councillor Steve Double said it would take between eight and nine years to bring in an alternative.
He explained the original project had started in 1996. He said: "That's 16 years ago and we still haven't built an incinerator.
"I accept it is not universally popular but it meets our needs. I am happy with the timescale and the advice is right, and therefore I believe the decision is the right decision for us."
Nine members of the cabinet voted in favour of the decision and one against.