The Naval Facilities Engineering Command, Hawaii’s Wastewater Treatment Plant at Joint Base Pearl Harbor-Hickam has reported that a clogged sand filtration polishing system touched off two partial bypasses — one last night and one today — at the effluent sand filtration system overflow weir.

During the bypass incidents, the plant discharged a total of about 18,000 gallons of fully treated and disinfected secondary effluent through its deep multiport outfall without polishing effluent sand filtration.

The sand filtration is one of the final advanced processes after full secondary treatment just prior to ultraviolet disinfection. It is an enhancement to improve the effluent quality and remove residual material following the fully functional secondary treatment system. 

Effluent quality is expected to remain within permit limitations, officials said in a notification report. Treated effluent was disinfected through the ultraviolet disinfection system prior to being discharged into Mamala Bay through the plant’s 12,500 foot long outfall and 150 foot deep, multi-port diffuser where it was assimilated intothe receiving waters with the assistance of ocean currents.