The first bitumen-concrete coating defects – cracks ranging in size from hairline to 1.5 cm wide and up to 45 m long - appeared on the reservoir slopes in 1981. As a result, the inspection gallery of the draining system shows signs of leakage. The cracks are evenly distributed across the entire coating perimeter and are repaired continuously.

Basic repair process is as follows: the cracks in the bitumen-concrete coating surface are opened up, cleaned, the crack and 20 – 100 cm of its surrounding area are treated by Dopraflex and subsequently by the BIT 40 KM emulsion, to be covered by an approx. 7 mm layer of modified bitumen and reinforcing REKO lacing , and topped by a modified bitumen cover.

In addition, gradual restoration of the bitumen sealing in the reservoir slope coating surface has been in progress since 1993. The Bratislava Engineering and Safety Department of the Waterworks Construction Company, (Vodohospodárska výstavba š.p.) was authorised to carry out qualified engineering and safety supervision at the entire Čierny Váh pumped storage hydroelectric power plant complex. Top reservoir monitoring includes also deformation of the bitumen-concrete sealing coating, deformation of reservoir embankment, deformation of the inspection gallery running along the bottom circumference, and leakage conditions in the inspection gallery.

Progressing deformation of the bitumen-concrete coating surface manifested as mild plastic flowing is evident from measurements and observations; vertical deformations in the embankments have been minimal ever since the measuring has started. The embankments are well consolidated. There are seasonal seepings, as monitored in the inspection gallery by a system of draining pipes; increased leakage reappears each winter. Local seeping exceeds permitted limits.

Assessment and evaluation of components extracted from the bitumen-concrete coating samples lead to a conclusion that over 20 years in operation the embankments display a change in quality properties of the bitumen mixture sealant and its degradation.

J. VORLICEK - In: Water Management Bulletin (Vodohospodarsky spravodajca). - Vol. 42, 11(1999), p. 10-11.

Information & Contact:

Research Institute of Water Management,
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