Maui County said it is planning to comply with an Environmental Protection Agency proposal to increase the level of treatment at its Lahaina sewage treatment plant.
It will cost an estimated $3.4 million to upgrade the plant so it can treat all waste water with ultraviolet disinfection, said Kyle Ginoza, director of the county’s Department of Environmental Management.
About 20 percent of the waste water receives ultraviolet disinfection at the Lahaina Wastewater Reclamation Facility, he said.
The EPA announced Wednesday it was issuing a proposed compliance order to require Maui County to fully disinfect all waste water at the Lahaina facility by the end of 2013.
The EPA said treated waste water sent to the facility’s injection wells could exceed coliform bacteria limits set to protect drinking water.
Increasing the treatment level to the highest level "will ensure that bacteria will not contaminate a potential source of drinking water or be released into nearby coastal waters," the EPA said in a news release. "The additional treatment will also substantially increase the supply of recycled wastewater available for reuse by the county."
Ginoza said Thursday the county disputes the assertion that the brackish aquifer below the Lahaina Wastewater facility is a source of drinking water.
Although county officials maintain Maui County has not violated the Safe Drinking Water Act, it has agreed to cooperate with the EPA in setting a deadline for attaining a higher level of waste-water treatment at the facility, Ginoza said.
"We were going forward with a higher level of treatment anyway, and they (the EPA) just wanted a time line set, so we agreed that by the end of 2013 we would have the project online," Ginoza said.
The project would add one or two ultraviolet disinfection channels to the facility. The department still needs to go through the design process.
The Maui County Council voted unanimously July 29 to comply with the proposed order. The plan is subject to a 30-day comment period before it can take effect.
Earthjustice, a law firm that sent the county a letter of intent to sue on June 29, plans to proceed with its legal action, Earthjustice attorney Paul Achitoff said. The firm, which represents Maui community groups, alleges that pollutants from waste water from the Lahaina facility is entering coastal waters and damaging coral reefs.
The Lahaina facility, off Honoapiilani Highway, handles 4 million to 6 million gallons of sewage a day. The plant performs secondary treatment on all its waste water but only treats about 1 million gallons per day with ultraviolet light, which disinfects it to a level that allows it to be used for irrigation.
The remaining treated sewage is injected into the facility’s four underground wells, situated about 2,000 feet from the shoreline. A yearlong study was launched in July to determine whether and at what pace waste water was leaching into the coastal waters. The study is funded by the U.S. Army Corps of Engineers, the EPA and Maui County.
