Windward Oahu drivers take notice: Pali Highway will be closed in both directions this weekend so the state can shore up the hillside near the Pali Tunnels.

After a Feb. 28 landslide, the state has been clearing out a rock overhang at the cliffs on the Kailua-bound side of the tunnel near the hairpin turn. It’s since been discovered that a stream has been wetting the soil and rocks. Yesterday the cliffside sweated water down to Pali Highway.

The highway will be shut down from 8 p.m. Friday to 3 a.m. Monday, between Waokanaka Street and Kamehameha Highway at Castle Junction. Pali Lookout will also be closed as a result.

"A thousand apologies from the Department of Transportation," state transportation spokesman Dan Meisenzahl said. "This is not something we would do unless we really thought this was necessary to do."

The Kailua-bound lanes will then be closed Monday through Friday from 8:30 a.m. to 2:30 p.m., but Meisenzahl said the work will likely be completed before March 18.

A drainage canal helped divert water from Pali Highway when it was built in the 1950s. But for reasons not yet known to state engineers, the canal is no longer serving its purpose.

"The water found its way back, and it’s getting underneath the soil and getting between the soil and the rock, and that’s created a situation where we could perhaps have a landslide, which we already did," Meisenzahl said. "The water has a mind of its own, and it’s going to go where it would naturally go."

He said another landslide is not imminent, but crews wanted to complete the work as soon as possible.

A day after last week’s slide, crews removed about 22 dump truck loads of debris from a part of the cliff 60 feet tall and 30 feet wide, including boulders as large as 6 feet in diameter.

For this weekend’s work, crews expect to shore up a section 80 feet high and 70 feet wide.

"If you can do the math, that’s going to be a lot of materials coming down," he said.

The state will also have to clear vegetation and repair the drainage canal.

"As our engineers looked at this and the scope of the work (this weekend), that side might be affected," Meisenzahl said, referring to the town-bound lanes of the highway.

During the closures, drivers are advised to use the H-3 freeway or Likelike Highway as alternate routes.