According to the Ministry of Economic Affairs, the mining authority has these concerns “Considered by approving the 4th Main Operating Plan only for Part 1, which does not yet provide for the final installation of the end embankments”.
Officially everything was fine for a long time
According to WDR research, the district government of Arnsberg had in fact complained to the operator about the lack of evidence of the stability of the edge embankments. However, it did not revoke the quartz gravel and quartz sand surface mining permit until April 2021.
Also striking: According to the test reports that the operator had submitted to the responsible district government of Arnsberg since 2015 and which WDR was able to see, everything was officially still in order. And the district government itself had no objections to a total of ten appointments on site until spring 2021.
The Cologne public prosecutor’s office is currently determining how this fits together and whether sufficient measures have been taken to secure the embankments and the flood protection wall in this context. The latter is questioned by the two independent reports commissioned by the district government of Arnsberg and the city of Erftstadt.
Concerns about rising groundwater
At the beginning of 2021, the geological survey NRW had also reported to the district government of Arnsberg that the edge and end embankments could not withstand a rise in groundwater after the end of mining. Here is what he says in a February 2021 letter:
This is relevant if the gravel pit were to be converted into a lake in the future. The district government of Arnsberg informed the WDR: “The stability calculations attached to the application documents provided evidence that the existing embankments are stable. Random recalculations by experts from the city of Erftstadt and the district government of Arnsberg confirmed this in 2021.”
Minister of the U-Committee on the Flood Disaster
The Ministry of State Economy informed WDR that the correspondence between the geological survey and the district government from spring 2021 was not previously known to the ministry. Economy Minister Andreas Pinkwart said (PDF), also on Friday before the committee of inquiry of the Land parliament of North Rhine-Westphalia into the flood disaster. As head of the Supreme Mining Authority, he is responsible for the safety of surface mines. But, according to Pinkwart, the prosecution has asked him to suspend his own investigation until the investigation is complete. Investigators are investigating the suspicion that the operation of the gravel pit was approved despite serious deficiencies in flood protection.
Pinkwart does not rule out other causes for the sagging
Pinkwart stressed that it still needed to be clarified whether the concerns actually applied to the south side of the mine, which subsequently collapsed. He does not rule out omissions by the authorities, but according to his experts these have not yet been proven, Pinkwart said. The contractor concerned was required to have the flood protection systems checked regularly by competent persons. Records had been kept on this subject and, according to these documents, there had been no objections. To his knowledge, the cause of the gravel pit collapse is still unclear. This could also have been caused by the failure of the flood protection upstream of the Erft.
The flood disaster in mid-July 2021
During the flood disaster in Erftstadt-Blessem, the earth had collapsed into the gravel pit and several houses collapsed. Storms accompanied by unusually heavy rainfall caused catastrophic flooding in Rhineland-Palatinate and North Rhine-Westphalia in mid-July. Entire regions have been devastated by the water masses. 49 people died in North Rhine-Westphalia and initial estimates put the damage at around 13 billion euros.
In an earlier version of the article, WDR did not specify that the statements of the Geological Survey concerned the rise in the level of groundwater.
The WDR reports on this topic in radio news, on WDR television on WDR Aktuell on May 6, 2022 and on WDR-5-Westblick from 5:04 p.m.