Groundwater spring area in Březová nad Svitavou, 1st and 2nd Březová conduits
The spring area uses a great number of fissure water springs in Cretaceous strata in the vicinity of Březová nad Svitavou, supplemented mainly by rain water infiltration into the rock environment.
Out of four existing aquifers, prevailingly separate, two central ones are exploited. Water from the shallower aquifer is abstracted by two siphon pipes. The siphon pipe of the 1st Březová conduit with a total of 14 drilled unequipped wells with profiles of 650 and 635 mm and depths of 17-21 is located in a 300-long tunnel provided with a massive brickwork.
The abstraction part of the siphon pipe of the 2nd Březová conduit consists of 28 drilled wells in a depth of 12-18 m, and the abstraction pipe leading from the wells is connected to a rising branch pipes of the siphon pipe with a length of 688 m, located in a through channel with a formed concrete bottom and prefabricated walls and ceiling. Both the siphon pipes are terminated in technological stations with vacuum pumps, providing underpressure necessary for the siphon operation.
The deeper aquifer is exploited by the 2nd Březová conduit by 7 collecting boreholes with a depth of 80-130 m with submersible pumps, the discharge pipes of which lead to a common collecting main.
The permitted abstraction from the abstraction system of the 1st Březová conduit is 300 l/s, the recommended average abstraction from the abstraction system of the 2nd Březová conduit is 780 l/s. The actual abstraction is governed by the current hydrological situation according to the groundwater table and water demand in the service areas.
Water from the abstraction systems of both the Březová conduits is conveyed to a common water reservoir in Březová nad Svitavou with a capacity of 5 000 m3. This water reservoir is used to fix the hydraulic conditions in the siphon pipes and to provide necessary storage to control water abstraction from the spring area of the 1st and 2nd Březová conduits taking water from this water reservoir. This presented method of operation started in 1975, when the Březová reservoir was completed and put into service as a part of the construction of the 2nd Březová conduit. Originally, the feeding pipe of the 1st Březová conduit conveyed water from the abstraction system all the way to the city of Brno without storage.
1st Březová conduit
The conduit is made of cast-iron socket pipes DN 600 and 650, and along most of its length it leads through a narrow valley of the Svitava River in parallel with a road and a railway, which it crosses seven times. In the highly broken terrain between Blansko and Bílovice nad Svitavou, a total of 3 massive tunnels had to be holed to lay the pipes, the longest is 614 m long. The difference in altitude between the groundwater table in the spring area and the water level in the Holé Hory water reservoir, where the conduit ends, is 89 m and it ensures a permanent flow rate of approx. 264 l/s. For purposes of handling, the conduit is provided with a total of 17 sectional slide valves in the tunnels or separate houses and with six overflow pipes limiting the negative impacts of handling. A 20-m-tall tower had to be constructed for one of these pipes, which has been a dominant feature of the town of Letovice until now. The pipes are purged by 100 air-relief valves and 53 sludge valves in the lowest spots on the route. Water is abstracted directly from the conduit for Adamov and Letovice.
2nd Březová conduit
The actual conduit is 55,357 m long and it is made of steel pipes DN 1 000 - 1 200. It was put into testing operation in 1975. The conduit leads to the aforementioned water reservoir from Březová nad Svitavou to a 2 x 17,500 m3 water reservoir in Palackého vrch. The difference in altitude between the water levels in the water reservoirs at the ends of the conduit is 66.50 m, ensuring a maximum flow rate of 1,140 l/s. In the area of the watershed divide between Svitava and Svratka Rivers, the pipe is located in a through tunnel, 2,795 m long. The pipes are made of steel, longitudinally, and in some places spirally welded, with wall thickness of 10 - 14 mm. The pipe route passes under a railway line six times, it crosses the Svitava River several times and minor water streams are crossed many times along the route.
The conduit is equipped with 12 sectional clack valves. In the tube valve structure under Palackého vrch in Brno there are two check gates DN 600, one of them is used as a 100 % back-up. The water pipeline is equipped with 66 sludge valves, 64 automatic air-relief valves and active cathode protection.
In 1997 in relation to the construction of the Vír regional water supply system, the 2nd Březová conduit was interconnected with the conduit of the Vír regional water supply system in the Čebín junction, which enables mixing of water from two difference water sources in the water reservoir in Čebín constructed as a part of the Vír regional water supply system. This enables quality homogenising of harder water from Březová and softer water from Vír. A booster pumping station was installed on the 2nd Březová conduit upstream the Čebín water reservoir enabling increased flow rates in the conduit compared to gravity flow rates during operation via the Čebín water reservoir given a high water yield of the Březové n./Svit. Spring area.
Before the Vír regional water supply system was constructed, the 2nd Březová conduit had been an independent functional unit and its last section between the Čebín water reservoir and the Palackého vrch water reservoir is still the main long-distance conduit for the central service area in Brno. It ensures fluent regulation and supply from the Březová spring area at maximum water yield with the following technical limits:
Maximum gravity flow rate to the Čebín water reservoir 910-938 l/s
Maximum flow rate to the Palackého vrch water reservoir by-passing the Čebín water reservoir 1,140 l/s
Maximum carrying capacity of the Čebín water reservoir- Palackého vrch water reservoir section 1,140 l/s
Pumping mode at the inlet to the Čebín water reservoir max. 1 150 l/s (underpressure on the route)
Water quality in the Březová nad Svitavou spring area
The water quality in the Březová spring area is very balanced and meets the requirements set by standards (acc. to Directive of the Ministry of Health No. 252/2004 Sb.) concerning potable water without treatment. Some boreholes in second aquifer even meet the quality conditions for infant food and is also used for this purpose. However, due to the increased and, unfortunately, ever increasing content of nitrates (30 - 37 mg/l) it is generally not suitable for sucklings. In other respects, the content of minerals is balanced, the temperature is constant at 9 – 10 oC and it ranks amongst high quality, valuable kinds of potable water.
Water resource protection zones have been declared to maintain the existing condition.
Connecting of the 2nd Březová conduit with the Vír regional water supply system
At the municipality of Čebín, the route of the 2nd Březová conduit was diverted via the new sectional valve and the booster pumping station to the new water reservoir in Čebín, where softer water from Vír is mixed with harder, aerated water from Březová. The water is sanitarily treated by chlorine dioxide. The Čebín pumping station boosts water pressure and increases flow from the 2nd Březová conduit to the Čebín water reservoir during periods of high water yield of the Březová nad Svitavou spring area, when a water gravity flow into the Čebín water reservoir without pumping (up to 938 l/s) would be lower than the volume of water that could be supplied from the spring area via the 2nd Březová conduit. A part of the mixed water from the Čebín water reservoir is conveyed back via a DN 1 000 pipe to the pipeline of the 2ndBřezová conduit and then to the Brno water supply system via the Palackého vrch water reservoir. As an alternative in extraordinary cases it is possible to close the Březová water inlet to the Čebín water reservoir and convey the water independently of the operation of the Vír regional water supply system directly to the Palackého vrch water reservoir.
By incorporating the 2nd Březová conduit into the Vír regional water supply system, an important network of quality water resources, including the 1st Březová conduit, providing sufficient supplies of quality water for dynamic development of the whole Brno region and its surroundings has been established for many years to come. Its control makes it possible to manage possible adverse operating situations by combining these water resources providing the most favourable economic conditions.