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Honolulu started with $174 million upgrade to Hawaii’s largest wastewater treatment plant, according to a June 4 press release from the City and County of Honolulu. The project will increase the capacity and efficiency of the shipboard bioconversion facilities at the Sand Island Wastewater Treatment Plant.
The project will be executed by Baltimore-based design and construction contractor Synagro-WWT. Construction will be handled by Hensel Phelps, based in Greeley, Colo., and Yogi Kwong Engineers of Honolulu will serve as construction manager, according to the release.
In May, tests showed the Sand Island plant was treated the water has exceeded the allowable bacteria levels, Spectrum News reported, prompting warnings for the public to stay out of the ocean. Elsewhere in Hawaii, the the island’s sewage treatment plants are aging and poorly maintained, prompting a recent EPA crackdown, according to Honolulu Civil Beat.
This project aims to improve and expand the existing bioconversion capabilities of the Sand Island plant so that it can effectively meet current and future wastewater treatment demands, according to the release. Improvements include two new anaerobic digesters, two sludge storage tanks, a digester control building, and a new tunnel and basement. The scope of work includes:
- Relocation and reconstruction of the wastewater reuse pumping station.
- Removal of the old pumping station and several underground services.
- Energy supply to the maintenance and laboratory buildings.
- Construction of new underground services, electrical improvements and site civil works.
Other improvements include installing a new boiler system, hot water pumps, modifying existing digesters and piping, relocating and installing flares, a propane gas tank, and new product dosing systems chemicals, according to the release.
“This upgrade is a vital investment in Honolulu’s wastewater infrastructure,” the agency said in the statement. “With the new anaerobic digesters and sludge storage tanks, the plant will be better equipped to handle increased waste volumes, contributing to a cleaner and healthier environment for Honolulu residents.”
The works are expected to be completed in October 2028.