Erosion control work at Pali Tunnel in Hawaii

Geotextile reinforcement is part of an effort to stabilize a slope at the Pali Tunnel on the island of Oahu. More than 10 tons of mud and debris slid onto the highway there in 2006, closing it for days before the area was cleared and deemed safe.

The $700,000 Pali Slope Stabilization Project began in July 2009 and is expected to be completed before the end of the year, according to the state’s Department of Transportation.

Crews will remove loose rock and dirt, as well as clearing and grubbing the top 4in. of the slope on the Honolulu side of the tunnel portal, the DOT said.

Work also includes installing an anchor mat system that will cover about 16,800ft². The geotextile matting will be anchored 4ft into the ground. The DOT called it “a state-of-the-art, high-velocity, erosion-control system that is being used all over the country.”

After the geomatting, the slope will be hydromulched, with grass seeds sprayed onto the mat to solidify the erosion-control efforts.