A new facility has been established at Kasted water works outside of Aarhus, Denmark. The purpose is to secure a future-safe water supply for the area.
The intent behind the new facility is to ensure that the water supply fits the actual, real-time demand, improve work conditions for the staff and obtain the safest drinking water possible.
The facility holds six XL PE pipe water tanks with a total capacity of 2,000 m3. They replace a previous installation with one single water tank made from concrete. Working with only one tank is risky, as maintenance or contamination could mean a temporary disruption of the supply to customers. Further, constructions made from concrete cracks over time, and damages are difficult to detect.
The advantages of a facility with multiple tanks are flexibility and safety, as maintenance or cleaning can be completed without any interruption of the essential supply. Also, having as little stagnant water as possible is preferred to keep the water’s journey from ground to consumer as short as possible.
Full focus on natural high-quality drinking water
The water works produces more than 250 m3/hour from water drillings nearby. The water is then filtered and oxygenated before it is sent off to the water tanks. The main purpose of the tanks is to store enough water to ensure a continuous supply and keep out any contaminating dirt or bacteria from the surrounding soil.
Therefore, the tanks have an extra layer added on the outside, and the gap between the inner and outer layer is filled with pressurized air. This construction makes it possible to monitor any changes in the pressure, which could indicate a leak or burst in the tank.
The air above the water surface in the tanks enters and exits through an air filtration system, to prevent contamination from the inlet air. Relief and vacuum valves are installed on top of the tanks to secure the tanks from damage caused by sudden changes in air pressure. A small tap is placed on each tank for regular water quality sampling. The tanks decline slightly towards the inside of the facility, resulting in a self-cleaning feature directing any small particles to a sump pump at the end, where they settle and can be discarded.
In Denmark, drinking water treatment allows only oxygenation and filtering, whereas adding chlorine to the drinking water is common in many other parts of the world. This emphasises the need for a system where the risk of water contamination is brought to an absolute minimum.
To ensure high quality, it is essential for all components in contact with the water that they do not pose a risk of contamination or affect the water by taste and smell. The facility has been equipped with two DN400 AVK gate valves at the inlet from the pumping station, and DN200 AVK gate valves and butterfly valves with actuation for both inlet and outlet of each of the six tanks.
Benefits of automation within water supply
Adding more control to the facility equipment is the main driver in reaching the goal of a demand-based supply. Before, variations in demand were tackled through overcapacity, which no longer will be necessary as the facility will be able to respond to peak or off-peak hours, keeping the use of resources at a minimum.
The ability to remotely monitor and regulate changes in the facility contributes with many advantages: With the finalised setup, no staff will have to rush in if any unexpected behavior should be noticed as they can follow-up and adjust equipment settings from anywhere. This saves valuable time and efforts to the benefit of both staff and consumers.
Upcoming project with a similar setup
By now, five tanks are in use. One of three pumps is activated and currently sends 60 m3/hour to thousands of consumers in the area. The complete facility is expected to be up and running within the year.
A similar facility will be established in the centre of Aarhus city, where water will be delivered by the pumps in Kasted. The projects are carried out by Aarhus Vand A/S.