Early Thursday morning, the city will inspect the flap gate at the end of an outfall pipe at the Sand Island Wastewater Treatment Plant.
The inspection, which will take place from 1-5 a.m., requires the use of a deep-diving manned submersible.
City officials say the inspection is unrelated to last month’s wastewater spill, which involved 5,000 gallons of partially treated wastewater spilling into Honolulu Harbor and 20 million gallons flooding the plant’s interior.
Flows will be held back during low flow hours. The city anticipates no disruptions to water, sewer or roadways while crews perform the work.
The 84-inch outfall pipe transports primary treated effluent from the plant to a depth of 240 feet and approximately 2.3 miles off shore to blend back into the environment.
The plant services residents and businesses from Kuliouou to Salt Lake, including Kahala, Kaimuki, Waikiki, Manoa, Makiki, downtown Honolulu and Kalihi.