The City and County of Honolulu has kicked off an $85 million revamp of the Kailua Regional Wastewater Treatment Plant, betting big that new infrastructure will finally tame spills, shoreline pollution and those long-complained-about smells. The two-part construction push will upgrade the plant’s solids-handling and biological treatment systems that serve Kailua and Kaneohe, with work expected to stretch over several years and bring demolition and heavy equipment staging to the site.
Two big projects at the plant
The $85 million package centers on two major upgrades: a $61 million dewatering building that will strip excess water from sludge, replace an aging structure and add a new odor control system, and a $23 million overhaul of two biotowers that rely on microorganisms to break down contaminants. Both efforts are slated to wrap up in early 2029, according to Hawaii News Now. City officials say the work is one piece of a larger plan to swap out worn-out equipment across the facility.
Why regulators stepped in
The construction follows a string of treatment troubles that drew federal and state action. The U.S. Environmental Protection Agency issued an Administrative Order on Consent that requires added treatment steps and more maintenance at the Kailua plant, according to the EPA. The Hawaiʻi Department of Health then followed with a Notice of Violation and Order in June 2023 after multiple monitoring samples exceeded bacteria standards. That 2023 NOVO cited 13 enterococci exceedances and included penalties for late reporting, per the Hawaiʻi Department of Health. “They’re going to be completely gutted,” Environmental Services Director Roger Babcock said of the biotowers in comments to Hawaii News Now.
Upgrades already in place
Even before this latest round of work, the plant added an $11 million ultraviolet disinfection system late last year, and city leaders say it has been operating steadily after a testing period. The setup uses UV light instead of chemicals to knock out bacteria before treated water is released, according to the new $11 million UV system. The facility handles about 11 million gallons of wastewater a day from Kailua and Kaneohe, and officials say the ultraviolet equipment boosts shoreline protections while holding down operating costs. Contractors plan to keep much of the construction activity on site, and project managers say they will coordinate schedules to ease the impact on nearby streets and homes.
What residents should expect
City officials say the current projects are intended to cut the odds of future treatment failures and give regulators the assurances they called for when they ordered fixes. Neighbors should still brace for heavy truck traffic, construction noise and some intermittent odors when large pieces of equipment are moved, though managers say crews will try to keep disruptions in check. For now, the upgrades mark the latest chapter in a yearslong push to modernize Windward Oʻahu’s wastewater network and keep Kailua Bay cleaner for swimmers and everyone who uses the shoreline.
