Tailrace rehabilitation in Slovakia

At the Hričov hydropower station in north-eastern Slovakia, the requirement arose for parts of an open tailrace (discharge channel) to be rehabilitated. Concrete repairs carried out with Nafufill products and waterproofing with MC-Proof 601 HT and MC-Proof eco – all from MC – served to reinstate the tailrace’s resistance to chemical and mechanical degradation.

The Hričov hydropower station is located some 200 km northeast of the Slovakian capital Bratislava on the Váh, the longest river in Slovakia. The complex, which was commissioned in 1962, is integrated within the Mikšová and Považská Bystrica grid and produces an average of 59.1 GWh of electricity per year. The rehabilitation of the tailrace was carried out in the period from September to October 2019. The main contractor for the project was Revels s. r. o., with the site work being performed by NSM s. r. o., a long-standing customer of MC.

 

Requirement for resilient waterproofing

Due to the damage suffered by the concrete substrate, it had become necessary to seal the open tailrace against water leaks at various locations. The aim was to create a full-surface contact layer that would perfectly match the original concrete. The client further specified a coating offering long-term resistance to the mechanical and chemical degradation caused by the fast-flowing water, and also full resistance to UV exposure.

 

Selective repair work was likewise to be possible in the event of subsequent localised damage occurring. The solution proposed by MC, a combination of the two spray sealants MC-Proof 601 HT and MC-Proof eco, proved to be ideal in meeting the job specifications.

Flexible solution with spray sealants from MC

The concrete substrate of the tailrace was first blasted with high-pressure water. Holes and deeper damage revealed in the process were then repaired with products from MC's Nafufill series. With the substrate thus smoothed, the waterproofing layer was applied using either the bitumen-free, two-component waterproofing product MC-Proof eco or the single-component, flexible waterproofing slurry MC-Proof 601 HT, depending on the situation and the requirements of the tailrace section concerned. The special features of MC-Proof eco include very fast through-drying – largely independent of temperature – plus the twin benefits of high-strength adhesion to the substrate and good recoatability.

 

This reactive resin compound is also certified harmless to water hygiene in accordance with the strict criteria laid down by Germany’s AgBB (Committee for Health-related Evaluation of Building Products). Tested compliant with EN 1504-2, MC-Proof 601 HT is flexible, offers excellent crack-bridging and exhibits high UV stability. As well as being alkali-resistant, frost-resistant and open to diffusion, it is suitable for hot surfaces up to 70 °C and remains waterproof up to 1 bar.

 

In total, MC-Proof eco and MC-Proof 601 HT were used to rehabilitate an area of around 22,000 m2. Despite the logistical challenges presented by the remote location, the project team was able to ensure that there was always enough material on site throughout the entire application phase, thus maximising cycle rates and minimising tailrace downtime – as well as providing a new, durable coating solution.