A facility at Sand Island Wastewater Treatment Plant that converts waste products into dry pellets for use as energy or fertilizer is set for a $174 million upgrade, Honolulu Mayor Rick Blangiardi announced on Tuesday.

What You Need To Know

  • Upgrades to the In-Vessel Bioconversion Facility will increase the capacity and efficiency of the state’s largest wastewater treatment plant

  • Synagro-WWT will serve as the design-build contractor. Hensel Phelps will handle construction with Yogi Kwong Engineers serving as construction manager

  • Initial work will involve relocating and reconstructing the Effluent Water Reuse Pump Station, removing the old pump station and various underground utilities and supplying power to maintenance and lab buildings
  • The project is scheduled to be completed by October 2028

Synagro-WWT will serve as the design-build contractor. Hensel Phelps will handle construction with Yogi Kwong Engineers serving as construction manager.

According to the Department of Environmental Services, upgrades to the In-Vessel Bioconversion Facility will increase the capacity and efficiency of the state’s largest wastewater treatment plant.

Initial work will involve relocating and reconstructing the Effluent Water Reuse Pump Station, removing the old pump station and various underground utilities and supplying power to maintenance and lab buildings. It will also include the construction of new underground utilities, electrical improvements and site civil work.

Key upgrades will include two new anaerobic digesters, two sludge storage tanks, a digester control building, and a new tunnel and basement. Other enhancements will include installing a new boiler system and hot water pumps; modifying existing digesters and piping; and relocating and installing flares, a propane gas tank and new chemical dosing systems.

The project is scheduled to be completed by October 2028.

ENV called the project a “vital investment” in the city’s wastewater infrastructure.

“This upgrade is a vital investment in Honolulu’s wastewater infrastructure,” the department stated in a news release issued on Tuesday. The enhancements will not only improve the efficiency and capacity of the Sand Island WWTP but also support the city’s growth and development. With the new anaerobic digesters and sludge storage tanks, the plant will be better equipped to manage increased waste volumes, contributing to a cleaner and healthier environment for Honolulu’s residents.”