Cleanup and repairs after last Wednesday's landslide at the entrance to the Pali Highway will cost taxpayers about $100,000, state Transportation Director Rod Haraga said yesterday.

The transportation department was still tallying costs, and more precise figures were not expected to be available until tomorrow at the earliest.

The agency dispatched about 75 of its employees and Tajiri Lumber workers to remove debris, dig a trench and install barriers. The state also hired special-duty police officers to manage traffic and assist with other efforts.

Haraga said the preliminary estimate of "around $100,000, maybe a little bit below it" when all costs are tabulated.

Officials representing other agencies, including the Honolulu Police Department, said the landslide incurred only a minimal amount of additional costs for them. HPD spokesman Capt. Frank Fujii said some officers worked extra hours, either before or after their shifts, to assist with safety-related efforts tied to the landslide, which left Windward commuters stuck in gridlock through Wednesday and into part of Thursday. But no special effort was made to separate those costs from other accounting costs, he said.

"We did have some people held over, but it wasn't of any great significance," Fujii said.

Haraga said that immediately after the incident, engineering geologists were sent to examine the slope of the affected cliff "to make sure we don't have any more slippages." Things should hold now, he said, if the weather does not take a turn for the worse.

"The reason we had that slide was because a waterfall developed right at the worst possible place — right above the steepest part of the slope — and that's why that particular area came down in a landslide," he said.

The state has installed barriers that are designed to catch incidental dirt falling from the slope, Haraga said.

When the area is again dry — possibly within the next two to three weeks — state officials will blanket the slope with a coat of "hydro-mulch," quick-growing vegetation to provide some erosion control, he said.

Haraga said he also intends to ask the Highways Division to review its rockfall mitigation program in the coming weeks. The current plan, about two or three years old, needs to be updated "sooner rather than later," he said, because of the constant changes in topography around the Islands.

No one thought the Pali area struck by the morning landslide was prone to rockfalls, for instance, he said: "It's hard to out-guess Mother Nature."

All four lanes in both directions were shut down after the landslide, which occurred on the Honolulu side of the tunnel and trapped some cars inside one of the tunnels. Afternoon traffic was diverted to the Wilson and H-3 Freeway tunnels while other Windward commuters took Kalaniana'ole Highway around the coast. The two town-bound lanes were reopened Thursday night.

Reach Gordon Y.K. Pang at gpang@honoluluadvertiser.com.