Wahiawa Wastewater Treatment Plant to provide unrestricted-use recycled water

Jade Eckardt

WAHIAWA—The Wahiawa Wastewater Treatment Plant (WWTP) will soon be upgraded to become home to the City’s first Membrane Bioreactor (MBR). The upgrades will allow the plant to eventually meet the State’s highest recycled water requirements. Oceanic Companies, Inc., of Kapolei was recently awarded a contract to construct the MBR after making the lowest bid for the project at $26.7 million.

Former City Managing Director Kirk Caldwell, who recently became Acting Mayor after Mayor Mufi Hannemann’s resignation, said on Thursday: “The City and County of Honolulu has continued to invest heavily in our sewage collection and wastewater treatment system. This is a very high priority that will preserve our quality of life and ensure we have infrastructure that will serve us for generations to come. This project in particular introduces a technology that is new to the City and which will further treat our wastewater for use as recycled water.”

The project entails improvements and upgrades to WWTP, including new MBR filter treatment, new ultraviolet (UV) disinfection and new gravity belt thickeners, all which will aide in bringing the water up to reusable standards. The improvements will provide enhanced effluent water and reliability, including meeting the State of Hawaii’s current R-1 recycled water requirements, the City said.

Although it has been estimated that the completion of the project will take approximately 15 months from the start of construction, Markus Owens, Department of Environmental Services’ public communications officer, said they do not currently have a set date to begin construction.

“The Department of Design and Construction do a notice to proceed and the project must begin within six months of that. So they will probably begin in the next six months,” Owens said on Friday.

According to Owens, the City’s decision to install the MBR was reached after exploring other options.

“We had been looking at a number of different options rather than upgrading,” Owens said. “ They were thinking about sending the wastewater to Schofield, where it would be treated and used there. It was decided that it wasn’t in the best interests of the City to give it away, so they decided to upgrade.”

Agricultural farmers can re-use the treated water with the upgrade as recycled water, Owens explained. Another idea was to pipe the water to Mililani as recycled water—a project that would require a lot of funding and is not likely going to happen in the near future.

“We will bring [water standards] up to R-1 and right now it’s between R-1 and R-2, so it’s not reusable,” Owens said. “This MBR will make the water reusable.

According to the Guidelines for the Treatment and Use of Recycled Water on the City and County’s website, R-1 water is defined as treated recycled water that can be used without restrictions, while R-2 is disinfected secondary treated recycled water with restrictions on its uses and applications.

Built in 1928, WWTP is the oldest treatment facility on Oahu. The plant, which processes approximately 1.6 millions gallons per day, is the only City treatment facility that discharges into fresh water, the Wahiawa Reservoir.