A community group has taken a council to court over a controversial contract for a £600m incinerator.
Community R4C claims the contract for the Javelin Park facility in Gloucester, near junction 12 of the M5, was awarded unlawfully.
Gloucestershire County Council has denied this and said it ran a competitive process within the law.
The High Court will decide whether Community R4C could have qualified to bid for the new contract in 2016.
The group said previously that it had been working on a "much cheaper" waste processing plant and "would have bid for the contract".
It claims the county council broke the law when it awarded the operator, UBB, a new contract four years ago.
Sue Oppenheimer, from Community R4C, said: "We would have worked in a consortium with partners. We already had dialogue with all sorts of partners in the waste industry, in the finance industry.
"We could have put together a very credible bid that would have been half the price of what we're paying for the incinerator."
Councillor Nigel Moor said, "The council ran a competitive process following procurement law to select a company to deal with the county's household waste that can't be reduced, reused or recycled.
"The council received a legal claim from R4C in relation to that process and has lodged a robust defence. It would be inappropriate to comment further at this stage pending the court's consideration of this matter."
The hearing is listed for three days at the High Court in Bristol.