One-lane Koali Road is in danger of collapsing and will be closed during construction days from 7:30 a.m. to 5:30 p.m. A temporary gravel road has been built to connect Dole Street to the dead end of Koali Road, at Kanewai Field.

Many Hokulani pupils reach their school through Kanewai Field, and now more than 400 children will have to cross the temporary gravel road during recess, lunch breaks and physical education classes.

The contractor, Koga Construction, will have flagmen stationed at both ends of the campus to make the crossing safer.

"The traffic is the major concern," said Hokulani principal Donna Lum. "The impact is great and the safety issue is primary. We've been working closely with the city and the contractor and are taking it one step at a time. As long as they remain responsive and can help with monitoring, I think it is a workable situation."

Sandy Ponimoi, who lives directly across from a damaged retaining wall, looks over part of Koali Street that washed into Manoa Stream. Bruce Asato • The Honolulu Advertiser

A flash flood hit Manoa at about 6:30 p.m. Oct. 30, overflowing streams, washing out roads and sending mud and water into homes and schools in low-lying areas.

At the University of Hawai'i, 40 buildings were flooded. Damage was estimated at $100 million, including loss of contents and intellectual property.

Koali Road, just downstream from UH, was the next to be hit with a powerful torrent of water that overflowed the road, knocking down a utility pole and sending boulders downstream.

"The sound was so loud," said Koali Road resident Sandy Ponimoi, who lives directly across from a damaged retaining wall.

"I was ready to bail out. I had my clothes in the car and was ready to go."

Wayne Hashiro, acting director of the city Department Design and Construction, said a 160-foot section of the 30-foot-tall retaining wall destroyed in the flood will have to be replaced. Koali Road will be reinforced to make sure access to the area is safe.

"The excessive flow eroded the stream bank, and the wall collapsed," Hashiro said. "The homes are not in danger as long as we do the repairs."

Hashiro said more projects are expected to follow as federal money becomes available.

The repair work is set to start April 25 and is expected to take between four and six months, depending on the weather, Hashiro said. Heavy equipment will be brought in to move large rocks and rebuild the wall.

"People are worried in case there is another storm," said city Councilwoman Ann Kobayashi, who toured the construction site and talked with residents last week. "The school would like them to wait until summer, but you can't wait on these things. If the whole road goes, it will slowly eat into people's homes."

Larry Kanda, the state's Civil Defense hazard mitigation officer, said a Federal Emergency Management Agency evaluation of flood damage is expected by the end of the month. Also, the U.S. Army Corps of Engineers is doing a study of the entire watershed from Manoa Stream to Waikiki, which is expected to be completed in 2008.

"That is where all the major flood-control projects will be coming out of," Kanda said. "Once that study is validated, we can go after federal funds."

Possible projects include rockfall mitigation, bridge work and installing a water gauge system to provide a warning when water is rising, he said.

"In Manoa District Park there are some drainage systems we want to enlarge and extend the protective walls to lessen the flow of water into the residential areas. But those are going to take money that we don't have now."