The state Land Use Commission approved by a 7-1 vote the request for a 21-acre expansion of the site, where 64.5 acres have been used for landfill since September 1989.

But the conditional special use permit for an expansion is subject to several conditions, including "two milestones," said Anthony Ching, executive officer of the commission.

Mayor Jeremy Harris' task force on selecting a new landfill site, which city officials are in the process of establishing, must present recommendations to the City Council by Dec. 1, Ching said.

The City Council would then have to make its decision for the new site by June 1, 2004.

"If this has not occurred, then the permit will immediately expire," Ching said.

The expansion will give the city five more years of storage at the landfill and give the city time to ramp up recycling programs and settle on an alternative waste disposal method to reduce dependency on landfills.

The state's conditions are reasonable, said Frank Doyle, acting director of the city Department of Environmental Services.

"Certainly, we're pleased," Doyle said. "This is all part of a process of being able to have a new landfill up and running by the time that we have to get out of Waimanalo Gulch, which is five years."

If the city meets both deadlines and the expansion project proceeds, Ching said the Waimanalo Gulch landfill can be used through May 1, 2008.

"The size of the acreage in the area we're asking for (21 acres) is based on the quantity of materials that we feel will be going in there over the five year period," Doyle said.

Once the permit is approved, the city has said it would take about two weeks to get the first section of the expansion completed and ready to receive garbage.

Though the city plans to close the landfill within five years, officials have started to look for another site to build a new landfill, one that will only be needed to store ash material generated as a byproduct of H-Power. The city has identified 40 locations on O'ahu as possible sites.

Leeward residents have long complained about the landfill in their back yard, pointing at the odor and litter it generates.

Though the city initially proposed the landfill expansion to last 15 years, officials compromised with the community by committing to closing it within five years.

The cost to expand the landfill will come out of the $7.7 million it costs to operate it, city officials said.

Reach Zenaida Serrano Espanol at zespanol@honoluluadvertiser.com or 535-8174.