Re-damming of the equalising pond at the Möhne dam begins at the end of October

After the equalisation pond below the Möhne dam was emptied as planned at the end of August, the Ruhrverband will begin re-stocking the reservoir in the coming week. This concludes an intensive construction phase lasting around two months, during which numerous renovation and modernisation works were successfully implemented.

As part of the construction work, the culvert of the Westricher Bach - also known as the Birkebach - was completely renewed, among other things. The old structure no longer met today's technical and hydraulic requirements and was therefore replaced with a new steel mouth profile, which will ensure safe and more efficient water drainage in future. In addition, cone nozzle III on the bottom outlet pipe was cut off in order to create the structural conditions for further repair work in the coming year.

Important work was also completed on the secondary power plant. The minimum water discharge pipe, which can be used to discharge water into the lower reaches of the Möhne even if the turbines fail, was fitted with a new pipe with modern shut-off devices. In addition, numerous other operational and structural works were carried out on the dam wall, the valve houses and the outlet areas of the pond in order to maintain the facilities in the long term and ensure their functionality.

However, unexpected and significant damage to the two turbine inlet gates of the secondary power plant means that their full repair cannot be completed by the end of October as originally planned. The parts required for this have to be manufactured individually, as some of the components are based on designs that were not standardised when the plant was built around 70 years ago. The production of the spare parts is expected to take around four weeks. 

In order to be able to continue producing renewable electricity at the dam's main power plant, the equalisation pond will be refilled for a period of around four weeks from the end of October. The sealing elements on the secondary power plant, which have not yet been fully renovated, will be temporarily installed to protect the turbines during operation. In December, the pond will be drained again for around ten days. During this time, the gate panels will be removed, given a final overhaul at the factory, fitted with new components and given comprehensive corrosion protection. Once this work has been completed, the gates should reliably fulfil their function for another 20 to 30 years.

Parallel to the work on the equalising pond, diving work has already begun on the installation of inspection gates on parts of the operating outlets of the Möhne dam. It is hoped that the extent of the damage will be less than feared and that some pipes can be put back into regular operation in the foreseeable future.

This year's work marks the start of a multi-year renovation phase with which the Ruhrverband will ensure the long-term operational safety and performance of the Möhne Dam and its power plants. Preparatory measures were already taken last year and a construction road was upgraded. During the current construction phase, the quarry stone masonry on the dam wall, the slide gate houses and the wing walls of the cascades were repaired.

This year's construction campaign will be successfully completed with the upcoming damming and the final overhaul of the turbine intake gates in December.