Excess water in landfill
prompts concern over
potential for collapse

State and city officials are worried about the potential collapse of Waimanalo Gulch Landfill.

"Worse case, the disaster scenario is a complete failure, and it would slide down to the base of the gulch," said Councilman Todd Apo, the area councilman. "I'm not saying that's a ... reality, but if we lose the integrity and stability, it may prevent us from putting additional waste into that landfill."

But Steven Cassulo, landfill operator Waste Management general manager, said there is no cause for alarm and that the company is already addressing concerns posed by the state.

"Waste Management doesn't believe there is a safety issue at this point in time at all. We're actually putting in a buttress to add capacity ... at this point in time according to what the state is requiring permit-wise," Cassulo said. "The safety factors of the landfill stability is well within engineering guidelines."

Part of the concern centers on leachate -- water that filters or leaches through the landfill and collects on liners below.

Waste Management's permit allows for leachate to collect to a height of 1 foot on top of the liner.

Cassulo told the City Council's Public Works Committee yesterday that the leachate is at about 20 feet high at the base of the ash pit.

Eric Takamura, director of the city Environmental Services Department, said excess liquid is a concern for the city when it comes to the stability of the landfill located on a slope.

"When there's a lot of water, (the waste) tends to liquefy. Besides liquefying, the waste (the water) adds more weight," Takamura said. "If the waste mass moves ... it could take the liner with it."

Takamura said the city and state are awaiting an engineering analysis on the stability of the landfill. "They would run through the calculations ... to determine if the mass was stable," he said.

Cassulo said the additional water is the result of unusually wet weather in the normally dry Leeward Coast. Waste Management is already working to bring those levels down, he said.

"We're pumping it down. We're basically taking our pumps and pumping it down into a water tanker," Cassulo said.

He does not believe the amount of leachate currently collected at the landfill affects its soundness.

The Health Department has written letters to the city and Waste Management about its concerns regarding the stability and capacity of the landfill and has asked the operator for more information.

"We have our own investigation staff that are reviewing the records and doing our outside investigations, and we're looking at the data to see if there's any potential violations," said Thomas Arizumi, chief of the Health Department's Environmental Management Division.

Meanwhile, Cassulo also told Council members that what it originally thought were underground fires at the landfill turned out to be "elevated temperatures but no fires or combustion."