Department of Natural Resources
This is computer-generated a model of how landslide experts expect the land to fall into the quarry created there by Columbia Asphalt.
As of Friday, January 19, 2018
UNION GAP The landslide predicted for Rattlesnake Ridge probably won’t land on Interstate 82, according to Joint Information Center spokesperson Lisa VanClise.
But the emergency team that’s dealing with the imminent slide is preparing for the worst-case scenario, she said yesterday.
That would be a roadway covered with soil. I-82 traffic would immediately be routed to state Highway 97 at Union Gap.
The detour would go on down to state Highway 223, turn toward Granger and reconnect with I-82 at Granger.
The Department of Transportation has already put up the detour signs. Motorists can see them under orange wraps as they travel through the valley.
“We are monitoring the fissures very closely,” Vancise said. “We have lights, cameras, seismometers and 3-D imaging.”
The possibility of a slide arose when fissures were discovered in October at the top of the mountain on the east side of the freeway. They are mostly in the area of the Columbia Asphalt quarry.
The emergency team has declared that it’s a matter of when, not if the slide will occur.
VanCise said the separating land is moving away from the mountain’s crest at a pace of about 1.6 feet per day.
To protect motorists on the freeway, Transportation has placed a line of conex boxes (shipping containers) filled concrete Jersey barriers along the bottom of the mountain.
“Those will not stop the slide,” VanCise said. “We believe it will go in a southeasterly direction and fall into the quarry.”
VanCise said no one has determined the cause of the fissures. She said that if recent rains accelerate the slide event, there impacts should be minimal or nothing at all.
Thorp Road, which goes around he base of the mountain, has been closed for motorist safety.
The latest word on a possible time for the landslide is up to five weeks from now.