Honolulu names Wahiawa-area site for possible new landfill; water board warns of groundwater risk

Honolulu officials on Jan. 7 told a joint informational briefing of the House Committee on Energy & Environmental Protection and a Senate committee that they have identified a 150-acre agricultural tract near Wahiawa — about 1.5 miles past the Dole Plantation along Kamehameha Highway — as the city’s preferred site for Oahu’s next landfill.

The identification comes as the existing Waimanalo Gulch Landfill must stop receiving waste by March 2, 2028 under a State Land Use Commission decision, and city staff said Act 73 and other legal restrictions have sharply limited coastal and mauka options. The city’s Department of Environmental Services (ENV) officials said the Wahiawa-area site would use a modern double-liner and leachate-collection system designed to meet federal standards, while the Honolulu Board of Water Supply (BWS) objected, saying siting above aquifers risks permanent harm to Oahu’s drinking water.

The dispute matters because BWS says Oahu depends entirely on volcanic aquifers for drinking water and that contaminants from landfills, including PFAS (so‑called "forever chemicals"), can migrate into groundwater. The board’s manager, Ernie Lau, told the committee, “Oahu is 100% dependent on groundwater,” and warned that landfills are effectively permanent fixtures that can generate leachate that may be difficult or impossible to remove decades later.

City presentation and technical safeguards

Roger Babcock, director of the Department of Environmental Services, and Deputy Director Michael O’Keefe outlined why the city selected the site and described technical protections. Babcock said modern sanitary landfill design includes a dual liner (a geomembrane and a clay liner), leachate collection sumps and pumps, and monitoring wells, and the city plans to install two independent liner-and-collection systems so a failure in the upper liner would be detectable in the interstitial collection layer.

“We are 100% confident that we can design and operate the next landfill on this selected site,” Babcock told the committee, and he noted that the city will be required to complete an environmental impact statement (EIS) and obtain permits — including a solid-waste operating permit and air permits from the State Department of Health — before construction.

Babcock and O’Keefe also described other legal constraints that limited site options: Act 73 (2020) requires a minimum half‑mile residential/school/hospital buffer and prohibits construction inside certain conservation districts; federal rules bar landfills within 5,000 feet of airports and within tsunami inundation zones. The city said it had considered three legal “paths”: (A) seek permits for a site within the current rules (the path chosen), (B) ask the Legislature to amend Act 73 to reduce buffers or change conservation limits, or (C) seek to extend operations at Waimanalo Gulch if permitting fails.

Board of Water Supply objections and water concerns

Ernie Lau, manager of the Honolulu Board of Water Supply, reiterated that BWS had previously disapproved the six sites proposed in 2022 because they were above freshwater resources, and that the Wahiawa-area location was also over aquifer territory BWS seeks to protect. BWS provided data the committee reviewed showing Waimanalo Gulch’s leachate characteristics and reported annual leachate production at Waimanalo Gulch of roughly 3,600,000 gallons per year (about 9,800–10,000 gallons per day); BWS also noted that the Wahiawa area receives higher rainfall and therefore could generate more leachate than Waimanalo Gulch.

On PFAS, Representative Quinlan asked, “Is there PFAS in the leachate?” Director Babcock answered, “Yes.” Lau and other board members told the committee that PFAS and other persistent contaminants present special concerns because of their persistence and potential health effects; Lau noted EPA’s recent national primary drinking water regulations for PFOA and PFOS were set at 4 parts per trillion.

Treatment, monitoring and long-term obligations

City staff said leachate from Waimanalo Gulch is trucked and treated at the Honouliuli Wastewater Treatment Plant. BWS officials noted that treated effluent from Honouliuli is discharged via a deep ocean outfall and that some reclaimed water is reused locally; they also warned that, if a groundwater source were contaminated, BWS customers would ultimately bear treatment or replacement costs.

Federal standards require at least 30 years of post‑closure monitoring of closed landfills, and city staff said they would design and operate the site to meet Resource Conservation and Recovery Act (RCRA) requirements (the federal framework for municipal solid waste facilities and liner standards). City staff said an EIS, archeological and drainage studies, permit applications and design work would all be needed before construction; the EIS alone could take at least two years.

Legal and procedural pathways

City officials said they have not yet decided whether to pursue a special use permit for agricultural lands (the existing Waimanalo Gulch permit route) or a district boundary amendment that would change zoning; both processes carry different public‑notice, review and legal implications. Ernie Lau said BWS’s administrative rule (section 3‑301) embodies a longstanding “no pass” concept protecting caprock/coastal areas and that he had formally disapproved the earlier proposed sites in November 2022 and reaffirmed that disapproval after the December site announcement.

The city also reported that it engaged with federal military landholders and the congressional delegation to explore federal lands; city officials said those inquiries found operational, environmental or mission restrictions that limited options, and that the services were unable to make suitable federal land available.

What happens next

ENV said it has a contractor under contract to begin the EIS and will begin parallel tasks including land procurement discussions with the landowner, site design and required technical studies. City officials emphasized there is no final approval yet: the site selection initiates a multi‑year public permitting and review process that could be appealed to the board or further reviewed by the State Land Use Commission and the Department of Health.

Discussion highlights and community concerns

Committee members and senators repeatedly pressed for alternatives, raised long‑term concerns rooted in the Red Hill fuel‑storage controversy and asked whether the city had exhausted options that keep landfills off aquifers. Several legislators urged greater emphasis on upstream policies — producer responsibility, stronger source reduction and expanded diversion programs — to reduce the volume of material that must be landfilled. City ENV staff described ongoing and planned programs: an ash recycling project to produce sand substitute material for asphalt, a food‑waste composting program, expanded convenience‑center diversion pilots, expanded recycling drop‑offs and plans for lithium‑ion battery take‑back points at convenience centers.

No formal vote or final permits were recorded at the briefing. The committee adjourned after lawmakers and agency staff agreed to continue technical briefings and stakeholder outreach.

Ending

City officials framed the announcement as the start of a long, public and technical process driven by regulatory requirements and an impending March 2028 closure date at Waimanalo Gulch; the Honolulu Board of Water Supply said it will continue to oppose siting landfills above aquifers and pressed for more aggressive source‑reduction and producer‑responsibility policies to reduce future landfill need. The city plans EIS work and permit applications next; timeline and ultimate outcome remain uncertain and dependent on permitting, potential appeals and any legislative changes to Act 73.