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The historic town of Staufen
in southwestern Germany on
the western edge of the Black Forest is
experiencing some rather unexpected downward movement these days. Several
buildings, some of them historic, are experiencing cracking and distress and
are still sinking at a rate of approximately 1mm per week. Investigations are
underway, but everything seems to point towards drilling operations for
geothermal energy which were conducted last fall. [Editor] More after the break...[/Editor]
Seven borings, up to 140m
(460-ft) deep, were advanced by a specialty contractor to install geothermal
probes for heating of the town hall. This was planned to be a prestigious
project for the municipality utilizing renewable energy. However, shortly after
finishing the drilling, cracks appeared in the recently renovated town hall.
First the cracks were attributed to drying of the plaster after renovation, but
cracks increased and neighbors started complaining about the same observations
in the surrounding buildings (some of them up to 600 years old).
A geotechnical expert was hired to investigate the
problem. At this point, it is assumed
that the drilling operations may have triggered the settlement. In
approximately 32m (105-ft) depth, the drilling company encountered an artesian aquifer.
The investigator indicated that even though the boreholes were cased, water may
still migrate upwards, which may change stresses in the ground. It is planned
to advance another 60m (195-ft) deep boring to obtain a subsurface profile and
to perform additional investigations into soil permeability and stress
distributions.
Interesting problem
Thanks Wolfgang. I appreciate you keeping us up to date on interesting geonews from your old stomping grounds.
Fascinating problem. You don't really hear too much negative about geothermal, usually its pretty benign. But this is definitely a unique case. Anyone else ever heard of any problems related to geothermal wells? -- Randy (rockman)
...
Just to clarify -- because there seems to be a lot of confusion in the media about this, particularly by the hysterical "reportage" of the Daily Telegraph -- this is not a geothermal power generation project. This is a geoexchange project, where the steady temperature of the earth at relatively shallow depths is used to heat and cool buildings.
In properly drilled wells that are cased and correctly cemented, leakage from an artesian aquifer could have been mananaged -- if, indeed, that is what happened. The official report has yet to be reported.
The historic town of Staufen
in southwestern Germany on
the western edge of the Black Forest is
experiencing some rather unexpected downward movement these days. Several
buildings, some of them historic, are experiencing cracking and distress and
are still sinking at a rate of approximately 1mm per week. Investigations are
underway, but everything seems to point towards drilling operations for
geothermal energy which were conducted last fall. [Editor] More after the break...[/Editor]
Seven borings, up to 140m
(460-ft) deep, were advanced by a specialty contractor to install geothermal
probes for heating of the town hall. This was planned to be a prestigious
project for the municipality utilizing renewable energy. However, shortly after
finishing the drilling, cracks appeared in the recently renovated town hall.
First the cracks were attributed to drying of the plaster after renovation, but
cracks increased and neighbors started complaining about the same observations
in the surrounding buildings (some of them up to 600 years old).
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