OLYMPIC NATIONAL PARK — Park officials reopened Hurricane Ridge Road to unflagged 24-hour traffic on Tuesday, confident that no more basketball-size boulders would tumble onto the thoroughfare from an avalanche chute perpendicular to the road’s shoulder.
The 17-mile road was closed on Aug. 16, after Olympic National Park workers discovered the rock slide about four miles south of the Heart o’ the Hills ranger station.
It was reopened last Wednesday solely for daytime travel after a 7-foot rock berm was raised to 10 feet, and the berm’s base enlarged to prevent rocks and boulders from falling into the two-way traffic lane.
From then until Tuesday, two park flaggers were directing traffic to the popular park destination, while a monitor watched the slide area, which lies about 100 feet south of three closely grouped tunnels south of Heart o’ the Hills.
The flaggers stopped traffic when rocks started sliding down the chute.
The rate of rockfall gradually decreased, and the berm held back boulders that before would have sailed onto the road, park spokeswoman Barb Maynes said Tuesday.
The repairs cost about $10,000, she said.
“This was not the kind of thing where a big slide came down and covered the road,” Maynes said.
“This was just a slow and continuous stream of rock and gravel and debris.”
The most dangerous aspect of the slide were large rocks that tumbled down the chute and crashed onto the road and on its western edge.
“Basketball-sized rocks, and rocks larger than that, were actually coming out over onto the road,” Maynes said.
“They would get to the berm and bounce up and over the berm.”
The avalanche chute is in an area known for rockfalls, Maynes said, adding that slide conditions have been aggravated by warm, dry weather that undermines slopes and soil.
“What was different about this episode was, rather than being an occasional rock coming down or some gravel, this was a continuous stream of rocks and gravel mixed with debris coming down off over the course of several days. We didn’t want visitors going up there with big, basketball-sized rocks in the road.”
The rocks that rolled down the chute formed a large mound of rock and debris on the east side of the road that workers packed into the berm to enhance and enlarge the barrier.
Round-the-clock vehicle access to Hurricane Ridge extends through Nov. 1.
A date has not been set for the beginning of the limited-access winter season, during which the road will be open from 9 a.m. to dusk Fridays through Sundays — weather permitting — until March.
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Staff writer Paul Gottlieb can be reached at 360-417-3536 or at paul.gottlieb@peninsuladailynews.com.