Windward O'ahu residents should expect more heavy showers today and tomorrow, though it would be hard to top the torrent that hit the Kailua area yesterday.

Maunawili recorded 13.84 inches of rain in the 24-hour period that ended at 8 p.m. last night. The St. Stephens area got 10.05 inches in the same period.

Other parts of Windward O'ahu, from Waihe'e to 'Ahui-manu to Kane'ohe, got more than 4 inches during that time.

The rain caused flooding and a brief closure of Kapa'a Quarry Road yesterday afternoon, and also contributed to a sewage spill Monday night at the Kailua Wastewater Treatment Plant.

Heavy rainfall while workers were trying to replace a vital screen contributed to a sewage spill at the sewage plant, where 14,000 gallons of untreated fluids overflowed the facility.

The untreated wastewater, which spilled onto the plant's driveway and drainage system, was collected and disposed before the night was over, said Silvestre Ulep, chief for the city wastewater treatment and disposal division.

The affected area has been disinfected, Ulep said.

Warning signs were posted after the spill but removed yesterday because none of the material left the plant grounds, he said.

"We have determined there was no spill to the receiving water, so there's no need for signage," Ulep said. He explained that a manufacture's representative was helping to install a new bar screen at the plant, but workers were unable to complete the task.

The bar screen has nothing to do with recent fines over foul odor coming from the plant, Ulep said. Last week, the state fined the city $177,600 for eight odor-control system and 15 fence-line emission violations from January through July of this year.

The bar screen was old and rusted and needed to be replaced, he said.

Chris Soares, administrative assistant at 'Aikahi Elementary School that is next to the treatment plant, said the spill didn't cause a foul odor like the plant was sending out last week.

"Today, we've been very blessed," Soares said. "It hasn't smelled. We haven't noticed any other problems."

Since the contamination was confined to the facility's grounds, the state Department of Health will not require any testing, said Kurt Tsue, spokesman for the department.

Monday night, workers weren't able to power a grinder on the screen and were removing debris manually every hour with rakes, Ulep said. The grinder cuts trapped materials on the screen into pieces.

The first onslaught of rain that rushed through the system brought huge amounts of debris at about 8:50 p.m., clogging the screen and causing the overflow, he said. "In the first flash of the heavy rain there was just too much debris," Ulep said. "It just so happened that the equipment was not completely installed."

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com.