The paths of the water are underground. This applies – at least for the moment – to the dam in mauthaus. Wednesday marks two months since the automatic control system sounded an alarm and reported leaks in the area of the two supply pipes – and one of the pipes has been out of service for just as long. It is still unclear how the accident could have happened. But that will soon change.
Because an inliner – an inflatable plastic hose that seals the pipe from the inside – has been installed inside the defective pipe. If everything goes according to plan, in a few days the water could again flow through the channel that was originally intended for this purpose. But before that, there are extensive tests to be carried out. Those responsible for this decisive step do not want to leave anything to chance.
"We want to put the inliner into operation as soon as possible", confirms the head of the kronach water management office, hans hemmerlein, at the request of the frankischer tag. Because it can still be seen that around 25 liters of water per second are escaping somewhere in the dam. "This is a very small quantity, which we measure constantly. The trend is downward. But of course we have to look closely at where it comes from."
A leak at the bottom outlet of the kodel dam is just as conceivable as a leak in the second supply pipe that currently transports the raw water. "It could be that the second pipe also has a leaking sleeve or a crack. But we won’t know until we can shut it down and examine it."
But that, in turn, is only possible when the inliner is in operation and reliably transports the raw water to the plant building. The water authority is currently coordinating with the long-distance water supply company on what exactly is to be tested and how.
A panel of experts consisting of the kronach authority, university professors, the ministry of the environment and the state office for the environment, regularly exchange their views. "It’s a question of testing how the material behaves under land", explains hemmerlein. "We need an exact measurement of the inliner and have to predict dynamic movements."
After all, it was a 300-meter-long pipe with bends in it. "Wherever it is not straight or the material changes, vibrations can occur." So far there is no comparative case. "This has nothing to do with what the kodel dam was originally built for."
Despite all the calculations, no one could say with certainty how the tests would work out in practice. According to hemmerlein, problems can occur especially at the interfaces. "The permissible airspeed we have in normal operation is three meters per second." That was 600 liters pushing through the pipe every second. "We’ll have to take a closer look at the tests first."
Since the inliner is already in place and the water is currently being pumped out with fire hoses via the spillway, the THW helpers have now been able to roughly print out the water from the spillway. "However, they are still on standby and, if necessary – depending on the distance – could be back here in two to five hours." For the time being, the equipment has remained at the kodel dam for safety reasons.
Praise for THW
The head of the water management office feels it is important to once again point out the tremendous work that dozens of THW emergency workers have done on site over the past eight weeks: "this was an absolute tour de force for the THW. This shows how important and how good the people who work there are, and how much they are willing to volunteer for the community."
If the tests are successful, hemmerlein and his colleagues will finally be able to determine the path of the leaking water – and thus also the cause of the accident.