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Friday, Oct. 24, 2014

Landslide could take months to clear and stabilize

By Amy Joi O'Donoghue, Deseret News

Published: Wed, Aug. 6 5:15 p.m. MDT

 A home is destroyed by a landslide in North Salt Lake, Tuesday, Aug. 5, 2014.

A home is destroyed by a landslide in North Salt Lake, Tuesday, Aug. 5, 2014.

(Trenton Jensen, Skyward Aerial Imaging)

SALT LAKE CITY — The subdivision developer where a North Salt Lake landslide wiped out one home on Tuesday and threatened several more said it could take months to clear the earthen material and stabilize the mountain.

"We'd like to get it taken care of before the snow flies, and that is optimistic," said Scott Kjar, vice president of Eaglepointe Development.

North Salt Lake officials and Kjar's company are waiting until the earth dries out and probes can be inserted to measure any movement in the landslide how much water is present.

"We need to determine if it is moving and put together a plan that will prevent damage to any other homes," Kjar said.

Eaglepointe has arranged for emergency housing accommodations for displaced families and will follow the engineering lead of North Salt Lake city officials.

"It is wait and see. I can't make any prognostications," he said. "We just have to wait until we get the information back from the engineers and get our plan together with the city. … We need to do what is prudent and reasonable based on what (the engineers) see."

City Manager Barry Edwards said a team of experts has declared the landslide site off-limits until it has a chance to dry out.

"We did not get as much rain as we thought (Tuesday), so the hillside is moving at a much slower rate than it did in the past," he said. "There is still sloughing a little bit. … Our plan of action is weather dependent and all of the geotechnical people agree that you can't get on top of the slide until it has a chance to dewater."

Clay and gravel

Kimm Harty, deputy director of the Utah Geological Survey, said a number of factors were likely at work to cause the landslide, including easily shifting gravel material sitting on top of clay, the presence of water and slope of the mountain.

"The rain could have been the last straw, but this sounds to us that this was a landslide in the making for quite some time."

Landslides are a common occurrence throughout Utah, she added, but as urban development encroaches on hillsides, risks can increase.

"We have looked at a number of large landslides in the last five to 10 years, with many of them impacting a road or transportation. They have not been hitting too many houses," she said. "In wet years, you have landslides in urban areas all over the place. This one is pretty big, bigger than what anyone would have expected."

The Utah Geological Survey maps geological hazards throughout the state, including landslides, but does not perform risk assessments on private property, she said. The information the agency collects is shared with city and county governments to ensure the most current data can be incorporated into land planning decisions.

"People trust their governments. If they are allowed to build a house on a piece of land, they think it is safe, and that is not always the case. You can tell people to do due diligence," she added, "but should homeowners be expected to do their own landslide investigation? Government is not going to get it right 100 percent of the time, but they do need to do the best they can to get it right."

Eaglewood and Eaglepointe

Kjar said the Eaglewood and Eaglepointe subdivisions that occupy the bench in North Salt Lake include 1,500 homes that were built in 19 phases — the last of which has been idled due to the landslide.

The homes were planned and plotted with layers of review that included geotechnical engineers who assessed slope stability and suitability to build, he said.

"We have not had any problems to speak of up to 18 phases," he said. "Whenever we do development the city gives us a lengthy list, it is mind-boggling the list. … We follow those lists of what the city has us do … with inspections all along the way. "

He said the site — home to a gravel pit in the 1990s — includes areas where homes could not be built, such as the area where the Eaglewood Golf Course was put in.

Harty said the area would include ancient Lake Bonneville gravel sitting on top of older, volcanic rock that has been weathered into clay. Even a gradual slope experiences the force of gravity, with erosion that is assisted by water that is most likely naturally occurring with springs in the area.

"The rain could have been the final straw," she added, noting that this traditional-style landslide is a slow moving force of nature that can easily cause millions in property damage.

Edwards said the city has gone back and looked at the planning documents associated with Eaglepoint, adding he believes the city acted appropriately.

"We believe we followed the law. We required the developer to provide the appropriate studies. … We are not seeing any glaring errors."

Harty warned that if one area of the hillside can give way, the slopes surrounding the Tuesday landslide may be vulnerable as well.

"They really got to study a way to make that area more stable so the people across the street can get to sleep at night."

Email: amyjoi@deseretnews.com, Twitter: amyjoi16

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1. Shaun
Sandy, UT,
Aug. 6, 2014

I do not feel sorry for the home owners who built a home on a hill like this. It should be common sense that there is a chance that your home could be destroyed by a landslide.

2. marxist
Salt Lake City, UT,
Aug. 6, 2014

Tour North Salt Lake. In the new eastern part of town you will see many steep slopes with "retaining walls" made of boulders - not anchored to anything. All of this appears precarious at best. I would wager that three quarters of the new part of town (on the hillside) is in high slide potential areas. I hope I'm wrong.

3. marxist
Salt Lake City, UT,
Aug. 6, 2014

RE: Shaun "I do not feel sorry for the home owners who built a home on a hill like this. It should be common sense that there is a chance that your home could be destroyed by a landslide."

Well I do feel sorry for them. They had a right to expect the city and developer to protect their investment. The purchasers had a right to expect due diligence from the city and the developer.

4. marxist
Salt Lake City, UT,
Aug. 6, 2014

And here's something else I worry about. I live in the older part of North Salt Lake. Just east of us is a steep vertical displacement created by the Warm Springs branch of the Wasatch fault. The developers have been allowed to build above us, creating housing lots with boulders, some of them very steep. These retaining "walls" are not anchored in anything. What is going to happen if we have a big quake?

The Warm Springs fault slipped just before the pioneers came into the valley ~ 6 to 7 Richter. What would happen to us if such should occur again? Are all of those boulders going to roll down on us (along with their houses? It could happen. It would be a fitting conclusion to the sorry domain of North Salt Lake.

5. JWB
Kaysville, UT,
Aug. 7, 2014

In many countries it is not the rich who build homes on a mountainside. When this gravel pit was used they took out the bones or backbone of this mountain. There was nothing to hold their fill dirt back, especially if they only met basic or minimum requirements for a slope that had a body of ancient dirt underneath. These people were more fortunate than the Rockville people. However, in a city that built it's tax base on this mountain, the gravel pit was an eyesore and not making money anymore. To put monster homes on the pit without mortgage processes is almost a crime not to provide some protection to people and their family. From the letter from the developer stating the city owns a lot of the land would say there is some problem in their process. People from other countries would expect the land of the free to protect them through the normal process. However, they did get out of the house but is definitely battle damaged.