Warning signs were posted around parts of Kane'ohe Bay yesterday following a sewage spill that dumped about 11,250 gallons of untreated wastewater into the bay.

The state Health Department advised people to stay out of the water between Pohakea Point and Mahalani Circle after the pressured sewer pipe broke, spewing the wastewater into the bay near Coconut Island for about an hour and 15 minutes.

The break occurred in the same pipe and place as one on March 16 that caused an estimated 3,100 gallons of wastewater to spill into the bay, city officials said. A third spill also occurred in a private wastewater system in the same area in March.

NEW PIPE IN WORKS

City officials said they repaired yesterday's break by mid-afternoon, and a contract has been signed to permanently replace the 40-year-old, 8-inch ductile iron pipe leading from a pumping station at 45-007 Ka-Hanahou Place with a more durable high-density polyethylene pipe.

"Work on a permanent replacement for the pipe will begin as soon as materials arrive from the Mainland," said Ken Kawahara, a spokesman for the city's Environmental Services Department.

The new pipe should be in place by the end of the year.

LARGEST SPILL OF YEAR

Yesterday's spill was the largest of the year as the city struggles to deal with an aging sewer system. Ultimately replacing the old sewer pipes throughout O'ahu is expected to take decades and cost several billion dollars.

After a city employee spotted water leaking from the pipe about 8 a.m., tanker trucks were used to divert and haul wastewater from the area while the pipe was shut off and repaired.

The pipe is part of a long network that takes wastewater from Kane'ohe to a treatment plant in Kailua. The pumping station is used to keep the sewage flowing through low-lying areas before it reaches the treatment plant.

The state Health Department's Clean Water Branch plans to monitor the water until it is clear.

Mike Tsuji, enforcement chief for the Clean Water Branch, said city and state officials remain in discussions about a comprehensive settlement that could cover fines for most past and future city wastewater spills, including the one yesterday.

Reach Mike Leidemann at mleidemann@honoluluadvertiser.com.