Members of the city Planning Commission will spend tomorrow hearing a legal challenge to the city's plan to extend the life of Waimanalo Gulch Landfill on the Wai'anae Coast.

The commission last month agreed to hold a contested case hearing to allow state Sen. Colleen Hanabusa, D-21st (Nanakuli, Makaha), and the Ko Olina Community Association to present their arguments in opposition to the extension.

The meeting is slated to begin at 9 a.m. in the Kapolei Hale conference room. While the meeting is open to the public, no public testimony will be taken.

The special-use permit to operate the 107.5-acre facility is due to expire in May. The city is seeking an extension through May 1, 2010. It eventually wants to expand the landfill and operate it for 15 more years.

Mayor Mufi Hannemann has warned that failure to extend the life of the landfill could force the city to take drastic measures. But those opposed to prolonging the landfill's use say they're tired of the political promises that the landfill will soon shut down.

Setting up a new landfill elsewhere would take years of planning, environmental studies and permit applications, officials say.

Hannemann has warned repeatedly that closing Waimanalo Gulch could force the city to seek space in a privately owned construction debris landfill in Nanakuli or seek a new site nearby, closer to homes and schools.

The city is evaluating several proposals that could lead to construction of a new garbage-to-energy facility in Campbell Industrial Park, and a reduction in the amount of trash going to the dump.

A decision is expected in January, but the project could cost $350 million or more and take years to build.