From “Twenty Thousand Leagues Under the Seas” to “Journey to the Center of the Earth” … in his novels from the second half of the 19th century, Jules Verne wrote of a fascination with the depths. Even today, it is difficult to imagine what things and circumstances may be found down there.
It felt just as unimaginable to me when we were invited by our client Schachtbau Nordhausen GmbH (SBN, a BAUER Group company) during a project retreat not only to visit the factory, but also to take a tour of a former mine.
Schachtbau Nordhausen is a company with a long tradition in the mining sector. The company has been engaged in sinking (i.e. producing shafts) since 1898/99 and is still very prominent today in the rehabilitation of mine shafts in Germany as well as in the excavation of new mines in Eastern Europe and Central Asia.
One of Schachtbau Nordhausen’s current projects involves excavating new drifts for the future workshop area in the Konrad mine in Salzgitter along with planning and constructing the headframe for the Konrad 2 shaft. The project has been commissioned by the German Federal Company for Radioactive Waste Disposal (BGE).
We at Fichtner Bauconsulting are assisting Schachtbau Nordhausen in engineering the headframe for the Konrad 2 shaft in the fields of architecture, HVACS (heating, ventilation, air conditioning and sanitation) and ELT (electrical) building services as well as in fire protection.
The Konrad 2 shaft acts as one of two access points to the former Konrad iron ore mine, which is currently being converted into a repository for radioactive waste. Later, up to 303,000 cubic meters of low and intermediate-level radioactive waste are to be stored there.
To date, there is no operational repository available in Germany for the existing radioactive waste. For this reason, radioactive waste from the operation and decommissioning of nuclear power plants and research reactors is temporarily stored at various locations in Germany until it is transferred to a permanent repository.
Construction of the mine began in 1957. The ore was tapped via two shafts, with the Konrad 1 shaft being about 1232 meters deep and the Konrad 2 shaft about 999 meters deep. They were named after Konrad Ende, the former chairman of the supervisory board of Salzgitter AG. The mining operation lasted from 1961 to 1976. During that period, a total of 6.7 million tons of iron ore were extracted.
After extraction levels fell sharply, the mine was closed in September 1976. There were, however, initial investigations into whether the mine would be suitable as a repository for nuclear waste as early as 1975. Yet it was not until 2008 – after lengthy licensing procedures and lawsuits – that the conversion of the Konrad mine was finally approved, making it Germany’s only licensed final repository.
Construction has now been under way since 2008 and is expected to be completed by 2027. The cost of converting the shafts and the entire mine is estimated at 3.4 billion euros. The time schedule and costs give some idea of the complexity and dimensions involved in this project. It is impressive not only to me, but also to my colleagues at Fichtner Bauconsulting who are actively involved in this project.
The day of our visit to the mine began at 6 a.m. with breakfast in Nordhausen. On the drive to Salzgitter through the Harz mountains, we were then able to look at some of the region.
We arrived on schedule at our destination at the Konrad mine after an hour and a half and were greeted with a hearty “Glückauf”, the miner’s greeting that is ubiquitous there.
After passing through security, we were shown to the visitors’ center. There we were led to the changing rooms by two very nice employees and provided with miner’s clothes from underwear through to helmet.
Another important piece of basic equipment for any miner is the “self-rescuer”, a self-contained breathing apparatus that provides protection against sudden toxic gases and oxygen deficiency.
Following a safety briefing, we were then able to head towards the shaft. Passing St. Barbara, the patron saint of miners, and hammer and pick, the symbol of mining, we were led to the lamp room where there was a panel indicating which miner is currently in the mine. The miners working there again greeted us with a cheerful “Glückauf”. For a miner, anyone who goes underground with him is obviously seen as part of the community.
With a good feeling, I climbed into the unlit pit cage with my colleagues. It was essentially nothing more than a kind of elevator to the depths. But for one thing, it took much longer than an elevator ride, and for another, the ride wasn’t as bumpy as expected. I felt a distinct draft, and when I shone my lamp at the shaft walls, I could see how fast we were rushing into the depths.
After less than five minutes, we had reached the 990 m level. Following the cool headwind, we were now met by warm (about 35 degrees Celsius) dusty air.
Our converted “visitors’ cabriolet” awaited us a few meters further on, with which we were then chauffeured through the drifts. The ride had something of a “wild mouse” feel to it, but our experienced miner guide knew his way around down there and knew the individual levels and development stages of the mine like the back of his hand.
First, we were taken to an info point where we learned about the mine’s history, background and its planned development into a final repository. The size and distances of the mine openings made the dimensions of this project more tangible. We were most impressed. In addition to our guide, we were accompanied by a mining engineer who informed us about the development of the chambers and the bolt securing technique. The drift walls are secured with metal bolts and then sprayed with shotcrete.
We continued towards one of the storage chambers, which are much larger than the usual connecting drifts.
Another stop was the eventual bottom landing. The bottom landing is the underground entrance from the shaft to the repository. This is where the vertical shaft hoisting transitions to horizontal drift hoisting. During later storage operation, the casks with radioactive waste will arrive there via shaft 2. They will then be transferred to a transport vehicle and taken further to the storage chambers. Finally, the casks will be stacked there.
Some subsections of this major project are already completed, while others are still under construction. What is certain, however, is that great things are being achieved there. There are workshops, offices, a small filling station and employees who work there underground seven hours a day in the heat and dust to make the project a success. Just building the infrastructure down there with vehicles and machines from individual parts is in itself a challenge.
Covered in sweat and dust, I was glad after about fours to be riding the pit cage back towards the exit where I could shower and change.
Many thanks to the BGE and Schachtbau Nordhausen for enabling the tour to take place in spite of Covid. It was a fantastic, impressive experience!