photo courtesy the County of Hawaiʻi

(BIVN) – The Hawaiʻi County Mayor has signed an emergency proclamation in the event of a possible failure of the Hilo Wastewater Treatment Plant. 

“Engineering assessments have noted mechanical defects, structural deterioration, and extensive corrosion at the treatment plant that could result in a sewage spill at the facility, while deficiencies have also been found in the sewer collection system in Hilo,” a County news release stated. The proclamation authorizes emergency management measures to be taken in the event of such a failure.

The proclamation comes as a five year rehabilitation project for the wastewater treatment plant is set to begin next month. The County has awarded a $337 million contract to Nan Inc. to do the work, and a Notice to Proceed is anticipated in early March. 

The County is currently permitted to discharge secondary treated wastewater into the ocean via an outfall diffuser located within Puhi Bay in Keaukaha. According to the emergency proclamation, “the deteriorated condition of the Plant is in a state of failure, meaning there is imminent danger of an emergency impacting the County of Hawaiʻi, were such a failure to occur, and raw sewage to be spilled into Puhi Bay and surrounding areas whereby water currents may allow raw sewage to be further disseminated with very limited mitigation options.” 

“It is our duty to protect the health and safety of our residents as well as our environment,” Mayor Kimo Alameda said in a news release. “By moving forward with repairs and upgrades to our Hilo Wastewater Treatment Plant, we are making critical investments in our infrastructure that will serve the community for years to come. This emergency proclamation also allows us to take the necessary steps to ensure that we mobilize quickly and bring together all the necessary partners if a significant sewage spill happens anywhere in Hilo.”

Mayor Alameda has also “directed staff to develop a response and mitigation plan so that the County is prepared to address a sewage spill at any critical infrastructure location,” the news release states.

photo of the Hilo Wastewater Treatment Plant courtesy the County of Hawaiʻi

The Hilo Wastewater Treatment Plant was built in the early 1990s. The facility serves about 30,000 residents and treats 3 million gallons of wastewater per day on average.

Last year (March 2024), the County entered into an Administrative Order on Consent with the U.S. Environmental Protection Agency to repair or replace the facility and address other wastewater infrastructure deficiencies.

The County provided this information about the rehabilitation project:

The treatment plant project focuses on rehabilitating the primary and secondary treatment facilities by replacing critical infrastructure and integrating modern technology. Work will be done in phases to ensure the treatment plant remains operational during construction and safeguards will be in place to aid in emergency response.

Key repairs and upgrades include:

Improved waste removal: By replacing the headworks system, large debris and sand will be removed more effectively.

Better sludge treatment: New primary and secondary digesters, an anaerobic digester, and solids handling and digester control buildings will be constructed to improve waste processing.

Upgraded equipment: Outdated equipment will be replaced, water quality processes will be improved, and advanced odor-control systems will be installed.

Modern technology: A plant-wide supervisory control and data acquisition system will be implemented to automate and monitor plant operations. A new control and server room will be installed for better system management.

Increased reliability: The main switchboard, pumping stations, and critical facilities will be upgraded to make the plant more efficient and reliable.