Raw sewage spills
into Lake Wilson
An estimated 195,000 gallons of raw sewage spilled into Lake Wilson Sunday night, the city reported yesterday.
The spill occurred after a plastic manhole insert broke loose and jammed equipment at the Wahiawa Wastewater Treatment Plant, the city said.
The spill was detected at 8:30 p.m. Sunday after the manhole insert was caught in a device that grinds large materials in waste water coming into the treatment plant.
Because of heavy incoming sewage flows caused by heavy rains, the blockage could not be cleared immediately, the city said.
When the device stopped functioning, the sewage flow backed into Lake Wilson.
After the spill was stopped at 10:30 p.m., a pump at the treatment plant failed, eventually causing about 10,000 gallons of sewage to be given partial treatment before going into Lake Wilson.
The malfunctioning pump was repaired by 12:30 a.m. yesterday, and normal treatment resumed at 4:35 a.m.
The city is analyzing water samples from Lake Wilson for pollution levels, and warning signs have been posted at affected areas of the lake.
The spill was the second reported by the city since last week.
About 4.6 million gallons of raw sewage spilled into Honolulu Harbor, Nuuanu Stream and Kapalama Canal on Friday after a stray cat caused a short-circuit at a Kalihi sewage pumping station.