This project was already recommended at that time as the most economical variant of water supply for the region around Brno. The supply area comprises the communities in the Svratka basin below the barrage of Vìr, nearly the entire district of Brno and surroundings, parts of the city of Brno and parts of the districts Vyskov, Breclav and Znojmo.

The water reservoir for the regional water supply system is the impoundment of Vír built between 1950–57. An average amount of 100 l/s of raw water for the region of Nové Mesto-Zd’ár is taken from the impoundment and passes a water treatment plant. In 1962 the entire Vír valley was declared a water protection zone.

Assessment of the amount of water required up to 2010

Studies from the eighties have forecast an average water demand of 1,750 l/s and a maximum daily demand of 2,300 l/s for the year of 2010. Meanwhile, the figures were adjusted to the actual demand and revised estimates were made at the beginning of the nineties with regard to the liberalisation of prices.

The medium water demand for 1995 was set at 861.4 l/s, in 2000 at 994 l/s and in 2010 at 1,395 l/s. In total, the VOV will directly supply nearly 600,000 inhabitants in 2010 and also supply some parts of four neighbouring districts with supplementary water.

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Quality control for raw water

The possibilities of treating stored water is ensured by the water treatment plant of Vír that went into operation 35 years ago. The raw water has a low content of minerals and a relatively low content of natural organic matter and it is soft. Toxic heavy metals and organic substances have not been traced in concentrations dangerous to hygiene.

The extension of the VOV was began in 1988 with three adjacent constructions. Investment for the three constructions amounts to 3.5 billion Kronen. By the end of 1993 works were carried out at the first and second construction at a cost of 1.5 billion Kronen, while the third section – the mains and links to the individual communities is presently being planned.

As to the water work of Vír, it is planned to exchange the existing machinery of the vertical Francis turbine for peak loads with a smaller basic capacity equipment of 1.16 MV, so that the raw water taken from the water supply system can be used for the generation of energy.

The raw water is conducted from the separated part of the impoundment of Tos below the dam through a special DN 100 duct to the feed of the raw water tunnel. The tunnel has a length of 4,190 m and a diameter of 9.8 m2. Selective influx of column water was below 10l/s and was treated before reaching the receiving streams in the pit water purification plant.

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Water treatment in the Svarec plant

In the last section the raw water is channelled from the tunnel through the DN 1400 duct, where the installed turbine with a capacity of 210 kW is using the surplus pressure of the oncoming water prior to dosage and admixture of chemicals. From the intake structure the water is overflowed for ozonization. The preliminary ozonisation process is followed by a sand quick filter and subsequent ozonisation in the storage pool of 20,000 m3.

The basis for treatment is water purification by flocculation through aluminium sulphate with direct filtration and neutralisation by clay, that can be complemented by a two-phase dosage of ozone. The water purification plant is designed for a maximum daily capacity of 2.300 l/s, which corresponds to the a daily production of 198,000 m3. Operation of the plant is computer controlled.

The distribution of water prepared in the plan in the framework of the third construction phase comprises four main fields:
1. The supply of communities in the Svratka basin from Vír to Tisnov.
2. The supply of the western part of the region by the mains from Cebin below Moravsky Krumloc.
3. The supply of the southern part of the region through the mains from the water storage tank Bosonohy, through the water storage tank Moravany below Zlfoiujopve.
4. The supply of the eastern part through the mains, connected to the southern supply system near Rajhrad, through the water storage tank Prace up to the water storage tank of Slavkov.

The total length of the connecting pipelines for the communities will comprise 257 km, the capacity of the 57 proposed storage tanks will amount to 42,960 m3. (Source: aqua press Int. 03/99)
Renate Haiden

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Information & Contact:
Dipl.-Ing. Milos Brzák, Vodárenská
soustava Vír, s.r.o., Sobesická 156, 60300 Brno
Tel. 0042/5 4553 2111