Honouliuli WWTP portion of Consent Decree completed

News Release from City and County of Honolulu, May 10, 2024

HONOLULU – Mayor Rick Blangiardi today commemorated the city’s completion of the second major milestone within the 2010 Consent Decree – the full secondary treatment upgrade of the Honouliuli Wastewater Treatment Plant (WWTP).

The comprehensive upgrade, totaling $536 million, included enhancements such as the installation of aeration basins, a blower building equipped with turbo blowers, a mixed liquor distribution box, secondary clarifiers, and a secondary process pump station.   Additionally, significant improvements were made to various aspects of the primary treatment process, along with upgrades to civil infrastructure, electrical systems, and SCADA technology.

The Honouliuli facility, initially commissioned in 1978 as a primary treatment facility, and then upgraded to partial secondary treatment in 1996, has now been elevated to full secondary treatment capacity using modern, efficient technology.  The new plant was commissioned in January and has now been turned over to ENV operations staff ahead of the Consent Decree deadline of June 1, 2024.  This represents a significant step forward for the city to meet federal Clean Water Act regulatory requirements.

The consent decree was filed in federal court Dec. 17, 2010.  It halted years of legal action including a Sierra Club lawsuit, the 2007 Beachwalk lawsuit, and resolved litigation over secondary treatment waivers, along with U.S. EPA and Hawai‘i Department of Health (DOH) compliance orders.

In 2010, the negotiated consent decree included three phases and a 25-year implementation schedule, which was unprecedented and the longest timeframe allowed by EPA.  Phase 1 was the upgrade of the sewer collection system; Phase 2 was the secondary upgrade of Honouliuli WWTP; and Phase 3 is the secondary upgrade of Sand Island WWTP.  From 2010 through fiscal year 2020, the city spent approximately $1.3 billion in capital costs on the Phase 1 upgrades to the collection system.  The collection system consists of approximately 2,100 miles of pipes, 72 wastewater pump stations and associated force mains.  The city collects and treats nearly 100 million gallons of wastewater daily.

The secondary upgrade of Sand Island WWTP is being accomplished in two phases, with the first currently 50% complete, to be finished in 2026, and the second to begin in 2029 and completed by the consent decree deadline of Dec. 31, 2035.  The Sand Island WWTP is currently an enhanced primary plant that includes ultraviolet disinfection of effluent prior to discharge through a deep ocean outfall.

While the Honolulu ratepayers bear the burden of funding the consent decree mandated projects, the city employs modern, efficient technologies and uses optimum funding opportunities to save money and resources.  The city continues to work with regulators to ensure residents receive strong value and a clean environment for decades to come.

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