Map from the Draft EA.

(BIVN) – A project that aims to address identified deficiencies at the Hilo Wastewater Treatment Plant is studied in a new draft Environmental Assessment, published in late January in The Environmental Notice. 

The project is of major importance to East Hawaiʻi. Hawaiʻi County Mayor Mitch Roth recently told state lawmakers that the Hilo Wastewater Treatment Plant “could be the next Red Hill, releasing millions of gallons out into the ocean if we don’t take care of it.”

“So we’ve been working on this for the last couple of years,” Mayor Roth said during the legislative briefing. “Its probably going to be our biggest spend.”

Photo overlooking the southwest corner of the Hilo WWTP, from the Draft EA.

The wastewater treatment plant (WWTP) was constructed in the early 1990’s and serves the sewered areas of the Hilo community. The Draft EA states:

Recent condition assessments and a resulting master plan have identified a range of critical system deficiencies within the WWTP which threaten reliable treatment and the ability to provide a safe working environment for operations and maintenance staff. These deficiencies include severe concrete deterioration, malfunctioning equipment, and safety hazards. In addition, influent five-day biochemical oxygen demand (BOD) and total suspended solids (TSS) concentrations are greater than those which served as the basis of the original plant design. Moreover, the existing condition of the facility poses a threat to the safe and normalized operations of the WWTP. As the Hilo WWTP is the only wastewater facility that serves the region, it is considered to be critical infrastructure. Should the facility experience some form of facility/equipment failure, cessation of WWTP operations could constitute a risk to public health.

The document states that the project “is anticipated to cost approximately $300 million to construct,” and will be primarily funded by Hawaiʻi County. The project may also utilize federal funds through the State of Hawaiʻi Department of Health Clean Water State Revolving Fund Program, “which would require the Proposed Action to meet all National Environmental Policy Act (NEPA) and Hawaiʻi CWSRF program requirements,” the draft EA states.

Photo of the existing sedimentation tanks in the central-western portion of the Hilo WWTP, from the Draft EA.

The project consultant is the Wilson Okamoto Corporation. 

A statutory 30-day public review and comment period is underway. Comments are due by February 22, 2024.