Project aims to avert Kailua rockslide

A fence and cable mesh will be put in to catch falling boulders along Kailua Road

Workers began drilling a hillside along Kailua Road yesterday as part of an emergency project to prevent rockslides.

Prometheus Construction is expected to take eight months to complete the $5.8 million project.

Heavy rain in March caused multiple landslides, prompting the Department of Transportation to stabilize the hillside.

TOP 10 ROCKSLIDE HAZARD SITES ON OAHU: 1. Kalanianaole Highway at Makapuu 2. Kamehameha Highway near Waimea Bay 3. Kamehameha Highway near Kahuku 4. Kalanianaole Highway between Le Jardin Academy and Castle Junction 5. Kalanianaole Highway near Castle Junction (work completed in December 2004) 6. Kamehameha Highway near Kipapa Bridge 7. Kamehameha Highway near Wahiawa 8. Kailua Road before Kailua Town 9. Farrington Highway before Yokohama Bay 10. Kamehameha Highway near Wahiawa Source: Department of Transportation

On April 3, officials shut down the Kailua town-bound lane closest to the hillside. The median was converted into a temporary second lane for Kailua-bound motorists to reduce congestion.

Kailua Road is ranked No. 8 among the top 10 rockfall hazard sites on Oahu.

Workers are to install cable mesh, anchored wire mesh and a protective fence along the top of the hillside to prevent any boulders from falling onto the roadway.

More than a dozen boulders above the hillside will either be broken up or secured in place with bolts and cables. Some of the large boulders weigh more than 30 tons or are similar in size to a large pickup truck, said Cliff Tillotson, vice president of Prometheus Construction.

A concrete drainage ditch will also be installed to divert rainwater. To further reinforce the hillside, the area will be seeded with grass and erosion blankets will be installed before cable netting is put in place.

The affected area is about 1,200 feet in length, and 70 feet at its highest point, Tillotson said.

He noted the bulk of the project is installation of 800 to 1,000 anchor bolts.

To maneuver around telephone lines, large wagon drills will be hoisted up the hillside to drill 20- to 30-foot-deep holes for the anchor bolts. The work is expected to be done by January.

An overlay of about 30,000 square feet of cable mesh will be draped over part of the hillside where more rocks are present. Each cable mesh sheet measures about 12 by 24 feet and weighs 200 pounds. "By having that heavy net there, rocks just don't want to move," Tillotson said.

About 60,000 square feet of anchored wire mesh will be draped over the other part of the hillside where there is more soil. Helicopters will be used to drop the netting in place.

Workers installed a chain-link protective fence along the work site yesterday to protect motorists.

Once work to the hillside is completed, workers will restore the median with loulu plants as part of an agreement with the Lani-Kailua Outdoor Circle. Additional landscaping will be done along with the replanting of the palm trees.

Possible lane closures could occur. The sidewalk along the hillside will reopen after the project is completed, said Scott Ishikawa, Department of Transportation spokesman.

Tillotson said he hopes the weather will be cooperative as they start the project during the rainy season. "I'm hoping we don't get a heavy rain season," he said.

State Transportation Director Rod Haraga said, "This project had to start immediately. Now is a good time as any."

CORRECTION Friday, November 17, 2006 » The state Transportation Department is starting a project to stabilize the sliding hillside above Kailua Road at the entrance to Kailua town. A Page A3 headline yesterday incorrectly said the department would be doing roadwork to prevent a rockslide. Please see the applicable Corrections Page for more information.