by delivery of the compensation reservoir below Dobsina.
The Palcmanska Masa – Dobsina Water Work System (WWS) is situated in the western part of the Volovske hills. It exploits the morphology of the territory and the slope conditions between the river basin of Hnilec and Slana. The large altitude difference between the valley of the river Hnilec and the valley of the Dobsina Creek (330 m in the distance of 4.5 km) created suitable conditions for exploitation of water energy.
The Dobsina WWS consists of three main complexes: Palcmanska Masa accumulation reservoir in the river Hnilec, catching reservoir with the hydro-electric power plant in the valley Vlcia dolina on the Vlcia Creek, and the compensation reservoir below Dobsina in the Dobsina Creek.
The WWS was first commissioned in the beginning of 1953, with operation of the first high-pressure aggregate.
The WWS is an original from the water management – energetic aspect. It is the first water work (save for the historical Turcek water main from the 16th century) in the new history of dam construction in our country by carrying water from the river basin of Hornad (Hnilec) to the river basin of Slana (Dobsina Creek).
The reservoir with high regulation rate is used exclusively for the purposes of hydroenergy in another river basin. At the time of the project and in the first years of operation, together with the Orava Water Work, it represented significant power facility. However, the water work serves also for other purposes, being the so-called indirect effects.
From this aspect, the reservoir in the river Hnilec fulfills aesthetic/landscape and recreational/tourist functions. Thanks to the geologic conditions, the dams are designed as simple slim gravitation structures and the oldest of the concrete dams in Slovakia. It is the first high-pressure hydro-electric power plant with pumping in our country.
The most important from the aspect of dam construction in the world within ICOLD seems to be the sealing of the smallest object of the system – the dam of the Dobsina compensation reservoir.
The climatic, precipitation, and temperature conditions are in the given location unfavourable and moreover, suitable natural materials were found in a distant location. Therefore, two sealing materials were used –the local clay stabilized by cement and the so-called D-material, i.e. clay concrete and the sealing on the basis of polyvinylchloride (PVC) foils.
The Isofol BB sealing foil, sealed by a lower and upper layer of cardboard, is protected by the upper and lower concrete prefabricates. The originally designed sealing of vertical and horizontal joints of the sealing or prefabricates was not realised. This affected the lifetime of the upper layer of the cardboard which should have sealed the foil – it was damaged and locally unfunctional.
Both cases of the sealing case represent a new progressive sealing, i.e. sealing made of the PVC synthetic foil and holds primacy in the world within the ICOLD.
Tests of functional reliability of the foil and the whole sealing were carried out until 1992. In spite of extreme loading – hard climatic conditions, the foil and the whole sealing elements proved to, even after more than 40 years, functional with local breach of the foil.
The upper – protecting layer of the damaged cardboard must be replaced by a more flexible and more adaptable geotextile named Tatratex. The behaviour of the sealing and the foil should be further monitored from the aspect of functional reliability.
(In: Water Management Journal No. 10/2003, P. 4)
Information and Contact:
Prof. Ing. Michal Lukac, PhD.
Faculty of Civil Engineering of the Slovak Technical University
Radlinskeho 11, 813 68 Bratislava 1
Tel: 00421 2 5927 4111
Telefax: 00421 2 5296 7027
Ing. Anton Balaz
Slovak Water Management Enterprise
Radnicna 8, 969 39 Banska Stiavnica
Bodrog and Hornad River Basin Office, Kosice
Local Office in Poprad
Tel: 00421 45 41429