One expert thought a landslide in Gjerdrum would stop by the road



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GJERDRUM / OSLO (Dagbladet): A possible landslide would stop along the road, was the conclusion of the geotechnical report delivered in January 2015.

Overnight to Wednesday, the massive landslide was both north and south of the highway in question. Ten people are still missing after the Ask disaster in Gjerdrum municipality.

Action indicated

Near the crash site is the now evacuated Gjerdrum Life and Activity Center.

The municipality approved an extension of the center in 2015 after both the county governor’s emergency response staff and the Norwegian Directorate for Water Resources and Energy (NVE) originally opposed the plans.

The county governor and NVE were concerned about the ground conditions at the site. NVE indicated, among other things, that the municipality had not documented sufficient stability in the danger zone for fast clay.

“It is worth noting that any measures necessary to reduce risk may turn out to have to be implemented outside the area to be regulated,” NVE wrote in objection.

PHOTO: Ørjan Nerland / NGI
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Landslide limit

One year later, development was completed. The objections from NVE and the county governor came after what the councilor in the recommendation to politicians describes as “a lot of contact” with NVE and the consultancy Reinertsen “to trigger the objection.”

Reinertsen’s report shows that soil samples were taken at various locations.

‘No fast clay (discovered) has been detected in Reinertsen’s investigations. In the laboratory, doubtful drilling results have been analyzed and it has been verified that there is no living clay ”, the report says, among other things.

- The front wheels were off the edge.

– The front wheels were off the edge.

Furthermore, the entire area for the new planned building is assessed to be stable.

The geologist writes in the report that the area south of the highway is considered unsatisfactory, but that “any landslide here will not be retrograde and the natural boundary is the stiffer road.”

The estimated boundary of a possible landslide is also shown in an illustration, where it is marked with a dotted line along the Fjellinna Highway.

Challenging

A new building collapses here

A new building collapses here

In addition to the samples that Reinertsen took in 2014, a compilation of previous surveys conducted by NGI in 2003 was also conducted. These were compared with Reinertsen’s own findings.

In the documents of the case of the presidency and the municipal council of February 2015, the councilor writes that the consultants have concluded that “the area can support full development that the land use plan allows.”

– NVE, for its part, confirms that the documentation (…) is good enough for them to formulate their objection to the detailed plan, it is also indicated in the recommendation.

In general, the councilor further emphasizes that the development in the center of Ask and Nystulia is “challenging in relation to the fast clay deposits”.

MARTEGING: Gjerdrum Mayor Anders Østensen says he was not aware of NVE’s plans for new fast clay studios at, among other places, Ash since the New Year. Photo: Henning Lillegård / Reporter: Angelica Hagen
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– The councilor will follow up on the previous reports from 2003 and will establish the necessary requirements that have arisen according to the new guidelines and regulations of NVE since July 2014. The measures taken in 2007 and 2009 (Golf course and planning in Nystulia ) have contributed to significantly increase the stability of the building. in Ask, and enables several stages of construction in the residential and treatment center of Gjerdrum, as well as the development of the Ask center in its entirety, is stated in the councilor’s assessment.

– No comment

NVE has estimated that 60,000 people live on fast clay in this country. The Directorate has mapped more than 2000 fast clay zones.

RAS: A new building collapsed in Gjerdrum on Thursday afternoon. Photo: Øystein Sæthre / Dagbladet
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Dagbladet has asked NVE about the factual basis for assessing that the road would form a natural boundary for a possible landslide, as well as whether this information in the Reinertsen report was followed by NVE.

We also asked if ground samples were taken after the development of the life center and activities to investigate whether the construction work may have affected the ground conditions at the site.

– I have no comment on the story or the causal connection right now, says Toril Hofshagen, NVE East Region Director.

– Our total focus and all of our teams are focused on the acute phase of this action, says Hofshagen.

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