Slump continues slipping, shifting
John S. Hagen
Kelly Hill of Denali Drilling drills a test hole on Oceanview Drive on Jan 27. John S. Hagen photo.
Borough and state engineers this week finished installing sophisticated monitoring equipment near the slump causing earth movement, cracks and heaves in the Oceanview Drive and Lutak Road area. Another sudden shift occurred late Tuesday, expanding existing cracks by several inches.
Borough engineering company PND Engineers from Seattle set up control points around Lutak Road and Front Street to monitor ground movement. State geologist Mitch McDonald then added more monitoring equipment to a larger area that included sites as far as the Haines boat harbor and further down the Lutak corridor.
“That will give us a much larger range of activity,” said borough emergency coordinator Roc Ahrens.
In the last week, five test holes were completed to collect soil samples in and around the slump area and down as deep as 40 feet. The samples were sent to an Anchorage lab and results are expected toward the end of February, according to Ahrens.
The state Department of Transportation is also working to smooth out the large hump in Lutak Road caused by the slump movement.
Ahrens said he was contacted by the Alaska Tsunami Warning Center, which was interested in monitoring the situation in case movement stretched to the edge of the slump. Ahrens said it could cause a small, localized swell in Lynn Canal, but only to the extent of, for example, causing a small wave near Battery Point.
On Tuesday evening, the tsunami warning center station in Skagway contacted Ahrens to report it was recording some seismic activity in the Haines area. While it couldn’t be felt by residents the activity may cause more movement in the slump area. Ahrens said he went to the area and noticed that since 3 p.m. Tuesday there had been a sudden movement of a crack, increasing the size of the crack both vertically and horizontally.
“There is some seismic activity going on under us,” Ahrens said. “It is unrelated to the slide but could cause additional movement to the slide.”
Ahrens said the new monitoring systems allow engineers to begin compiling precise data they can use in modeling the characteristics and movement of the slump to begin developing solutions.
“Mainly it’s important for engineers to do modeling because, from that, the engineers can take that model of what the problem is and begin designing solutions to fix it,” Ahrens said.
Ahrens continues to post daily updates on the slump on the borough website and recorded updates at 766-2256.