«Hollow Grounds – Volumes Rising» is about the pursuit of control and the failure to maintain it. The work recounts a number of incidences within which an extraordinary turn of events has left lives in ruins, both economically and environmentally, sometimes with fatal consequences.

Whether building a geothermal energy plant, another subway line or filling an underground oil reservoir – each story begins with good intentions, a desire for progress and an unconditional belief in one’s abilities.

This unfounded confidence, however, together with a total lack of planning and/or uncontrollable forces of nature can quickly result in disaster.

Staufen im Breisgau – 2007

In the year 2007 the city of Staufen decided to drill for geothermal energy in order to heat the recently renovated town hall. Less than a month after the drilling took place, however, cracks began appearing within the walls of the building.

As a result of the drilling, the earth directly below the building and within its vicinity had begun to rise and physically lifted the entire old town. The cause of this cataclysmic side effect of the drilling was soon identified.

Through the drillings, the groundwater was put into contact with a stone layer in the bedrock containing anhydrite. When in contact with water, this anhydrite converted into gypsum and subsequently expanded, causing the entire ground above it to rise.

The original good intentions of the city to heat the town hall through geothermal energy, together with inadequacies in the accuracy of the drilling of the 7 holes, nearly led to destruction of some of the oldest parts of the town centre, the foundations of which date back to 1323.

Cologne – 2009

During the construction of a new subway line at the Waidmarkt in Cologne in 2009, an accident occurred that, as well as tragically claiming two lives, caused the Historical Archive of the City of Cologne, the largest of its kind north of the Alps, to collapse.

More than 1.7 million documents, manuscripts, minutes and other unique historical documents were rapidly engulfed in a gigantic hole of water, mud and debris.

Serious mistakes were made in the construction of a retaining wall, whose purpose was to support the surrounding ground during the excavation and construction of the new subway line.

It was only a matter of time before large quantities of mud and gravel were able to penetrate through the faulty wall, thus removing the very foundations of the city archive itself, which was situated only 15 metres away.

Although a restoration and digitalisation centre was erected in a warehouse just outside of Cologne, and 95% of the collection was recovered, the restoration of the material will take decades.

Various construction site workers and managers have been taken to court by the city in order to identify those responsible for the accident, whilst the total cost of the damage has been estimated by the city to be in the region of 1.2 billion euros.

Gronau-Epe – 2014

One morning in spring 2014, farmer Sundermann noticed that his cows were behaving very strangely. The cause was quickly identified as being a result of oil rising out of the ground. In the following months, the Sundermann family had to slaughter 10 cows and move into a hotel for a year before finally selling their farm.

Salt deposits, located around 1200m below the Sundermann family farm, had been flushed out using water by the company Salzgewinnungsgesellschaft Westfalen (SGW), resulting in huge empty cavities buried deep beneath the earths surface, some of which are larger than the Cologne Cathedral.

The saltwater itself is passed on to chemical companies while the cavities can be rented out to energy companies and used as reserves for crude oil and or natural gas.

Even the federal government is a lessee, storing vast quantities of oil in the event of a national or international crisis.

In the spring of 2014, it became apparent that a supply line to the S5 cavern located below the farm was leaking. Large quantities of oil leaked out at a depth of 214 metres, destroying the Sundermann family’s entire pastureland from one day to the next.

The leaked oil-water mixtures were sucked out and the contaminated soil masses were dug up. A simple solution was found to ensure that such an accident would not happen again. Double-walled piping of the caverns should now provide final safety.