Three companies vying to build a Hawaii island waste-to-energy incinerator say better proposals will come in if an Oct. 15 deadline for bids is extended.

The three finalists at a pre-bid conference also questioned whether the Hawaii County Council will approve a 25-year incinerator contract costing $125 million or more.

Hawaii Mayor Billy Kenoi wants to have the incinerator built before he leaves office in late 2016 and has said three months is long enough to prepare bids, West Hawaii Today reported.

Covanta Energy Corp., which operates Honolulu’s HPOWER incinerator, is one of the bidders. The others are Green Conversion Systems Inc., which was picked to build a Los Angeles incinerator, and Wheelabrator Technologies Inc., which won a $125 million bid to build a Hawaii County incinerator in 2008 that the County Council killed.

"This will be an expensive project, probably more than the project that was turned down," said Harvey Gershman of Green Conversion Systems.

"We feel the county can bear the cost of the facility," said Leithead Todd, county environmental management director.

The Oct. 15 deadline is a problem, company representatives said, compounded by missing information that the county so far has not provided. The mayor’s timeline for the project calls for a vendor to be selected by January and a contract signed in April.

The existing Hilo landfill has an estimated two years left. The landfill’s life could be extended to eight years if the county obtains a permit to steepen its north slope with more garbage.

"I don’t understand why the deadline is so tight when you have eight years left on your landfill," said Mark Lyons, a Wheelabrator representative. "I’m concerned you won’t get the quality of proposals you deserve if you don’t extend the deadline."

Steven Weber, from Covanta, asked for a three-month extension.

Kenoi said the deadline decision ultimately will be up to an evaluation committee.