The landslide at Gjerdrum – The alarm sounded after this

In the spring of 2008, the first houses in Nystulia were ready. Since 2003, it had been planned for housing in the city center of Ask in Gjerdrum. Large areas of vegetation were cut down, the valley was filled in for planning and the area prepared for construction.

In 2008 the first homes in the new housing area were ready. Soon after, in April 2008, the spring flood reached Gjerdrum. This meant that Tistillbekken and a tributary through the residential area had abnormally high water flow, causing significant erosion damage.

– Development must be stopped

Steinar Myrabø was then the leader of the local team of the Nature Conservation Association, working as chief engineer and hydrologist at Jernbaneverket. His special field was, and is, runoff and surface water management in relation to developments.

“Development in Nystulia must stop,” was Myrabø’s conclusion after an inspection of the area in 2008. He believed that ongoing development in the housing area, which now collapsed twelve years later, was the main cause of the housing problems. flooding and erosion damage.

He believed that no steps had been taken to collect and delay surface and wastewater. The 2008 warning has already been mentioned by the NRK and Romerikes Blad after the landslide early Wednesday morning.

Dagbladet has also seen the warning from the municipality that went to the developer. There, the developer is advised to implement immediate measures to prevent further erosion. It was sent from the municipality of Gjerdrum to the inhabitants just after the warning from Myrabø.

– Speak for itself

But now Myrabø and the Nature Conservation Association have also found the photographs of the area after the 2008 flood. It shows severe damage.

– The images speak for themselves and show the reason why the municipality and somewhat later the media were notified about the danger of rapid clay slides after the 2008 spring flood, with a lot of erosion and leaching in the area . You don’t have to belong to the Nature Conservation Association or be a professional to understand that you need to report incidents of this type that could trigger a rapid landslide, Steinar Myrabø tells Dagbladet.

The seasoned hydrologist and hydrogeologist believes there were good reasons to report in 2008.

– The current came from above the Ask center and carried a large amount of loose material through the residential area. This and the increased flow of water caused great erosion also below the residential area where the stream was closed. The stream closure was razed and destroyed. I warned that the municipality had to take action and do something, like building diversion measures, eliminating the stream closure, and revegetants in the areas along the entire stretch of the stream, he says.

– Rate

Myrabø was living near Ask at the time.

– There was a clear leaching in the area. Then there was a potential danger, because the water was digging a lot in the masses, he says.

Before the development of the residential area, there was a lot of vegetation and a natural ravine valley in much of the residential area. Now some parts have collapsed.

– It was a deep valley where the water came out, says Myrabø.

Own notice

He says it cannot be concluded that erosion and rising water levels led to the catastrophic landslide on December 30. So far, seven people have been found dead in the landslide, while three people remain missing.

– But it should have been addressed, so it couldn’t have been a possible cause of a landslide. It wasn’t done as we suggest, and the pictures show that erosion protection wasn’t done either, he says.

– Did you think of your own warning when you heard about the landslide?

– Yes of course. I hope that’s not what caused it. I also don’t know what action was taken after 2008. But from what we saw there in the spring and fall of that year, no one had.

Investigated

Work is now under way on the investigation of the case, where the police have the main responsibility to find out how the landslide occurred and who may be legally responsible.

The Norwegian Geotechnical Institute (NGI) and the Norwegian Directorate for Water Resources and Energy (NVE) are also working to collect information on past warnings, landslide hazards and the construction process at Nystulia, dating back to 2003.

Gjerdrum Mayor Anders Østensen (Labor Party) tells Dagbladet that it is difficult for the municipality to respond if hydrologist Myrabø’s warning was followed after 2008.

– Will work on the reconstruction of Gjerdrum

– There have been many points of view and opinions. The general attitude of the municipality has always been to cooperate without trying to question measures or safeguards. Things will be investigated and unions will work on it in the future. No one appreciates these responses more than we as a municipality, he tells Dagbladet.

The project’s developer, Odd Sæther, says it would never expand if it wasn’t considered safe.

– I live close to me and I have had young people and relatives here. It would not have been an issue to do something that is not safe. The important thing has been to stabilize the area, says Sæther.

– Help the police

– We must have a fairly defined perception of something before we begin to relate to everything that has been said before, and first we want a clear presentation of what happened.

He says that the municipality will contribute everything it can to the police investigation.

– No more hope

– We will align with everything we have to get answers. We are affected as a municipality, and we will appreciate the answers that can help us manage a municipality that is on clay, he says.

– But can you answer if there was a warning from Myrabø in 2008 and if it was followed up?

– Eventually there will be an answer, says Mayor Østensen.

– Acute phase

He fled with the daughters in his arms

14 buildings with 31 homes have been swallowed up by the ground. A thousand inhabitants have been evacuated and even more are without working electricity, water and sewerage.

– We are still in an acute phase, but we are moving towards a more long-term phase to start a production of services. At the same time, we will provide all relevant documentation in the case to help create the clearest picture possible of what happened, he says.

NGI has provided advice throughout the construction process and their preliminary review indicates that the construction has been carried out in accordance with current requirements.

The total of eleven reports reveal details of the security measures that were planned and executed.

NGI claims that for several decades they have investigated the soil conditions in the municipality of Gjerdrum. In the area that has now been evacuated, there are several construction cases where NGI and other actors have conducted site assessments. On Tuesday, NGI has been unable to respond whether Steinar Myrabø’s advice was followed or whether the measures he proposed were implemented.