The meeting, set for 7 to 8:30 p.m., is being held to provide the public with an overview of O'ahu's wastewater treatment system and explain why the city is asking that the U.S. Environmental Protection Agency continue to allow the city's Honouliuli and Sand Island wastewater treatment plants to operate with so-called 301(h) waivers from full secondary treatment requirements.

For years, the plants have been providing full primary treatment — in the case of Honouliuli, partial secondary treatment — to wastewater before discharging it more than one mile offshore, in ocean depths of about 200 feet.

"Denial of the waivers, which will force us to go to secondary treatment at both plants, is unreasonable, untimely, unfair and unnecessary," Hannemann said in a news release issued today.

"There's no scientific proof that less than full secondary treatment here causes any harm to our environment or to the public. In fact, some scientists have argued that what we're doing now is far better for the marine environment than if we were to go to secondary treatment at Honouliuli and Sand Island."

Full secondary treatment will require an estimated $1.2 billion in additional construction at the two plants," Hannemann said.

"That kind of expense is unnecessary, especially in light of our efforts to work with EPA officials to address far more pressing needs to improve our collection system, the 1,400 miles of underground mains that carry wastewater to our treatment plants," Hannemann said. "Requiring full secondary treatment at Sand Island and Honouliuli, which handle 80 percent of O'ahu's wastewater, could drive monthly residential sewer fees up to $300 in less than 20 years."

EPA informed Honolulu of a tentative denial of the 301(h) waiver for Honouliuli in March, and is expected to take similar action for Sand Island this fall.

The EPA has extended the public comment period on the denial for Honouliuli's waiver to Aug. 27.