Thanks to their modular design HOBAS GRP Reservoir Tanks can be quickly assembled on site without any special equipment.
Thanks to their modular design HOBAS GRP Reservoir Tanks can be quickly assembled on site without any special equipment.

The market town of Karlstetten is home to over 2000 people, and this figure has been rising steadily in recent years. As there are no lakes for swimming in the immediate vicinity, many homeowners in Karlstetten have their own pools that they fill every year beginning of summer. This caused considerable shortages in the potable water supply in recent years, making an extension to the water network essential.

To increase capacity, the investor opted for a HOBAS Potable Water Tank with a capacity of 250 m3, which can be increased to 320 m3 to cater for future needs. The tank consists centrifugally cast glass reinforced plastics (GRP) pipes – a 12 m long valve chamber and three 21 m long potable water chambers. There is also a connection for a fourth chamber if required in future.

HOBAS tanks are prefabricated at the factory and thanks to their modular design they can be quickly assembled on site without any special equipment. Fabrication from order release to loading on the truck takes four to six weeks, depending on the tank size. The largest tanks supplied by HOBAS to date are around 300 m3, but much larger ones are currently being planned. Delivery is generally just in time for installation, which means there is no need for large storage areas or to disrupt traffic. Their low weight and compact structure means the tank units can be transported by flatbed truck and not classed as expensive oversize loads requiring escort vehicles.

Installing the tank

Contractor Held & Francke installed the tank in Karlstetten.

First it excavated a pit measuring some 24 m x 9 m and placed a layer of the standard bedding material used for HOBAS tanks – gravel with a grain size of 8-16 mm.

At 7:30 am, the truck with the first part of the valve chamber drew up. The module with a width and height of 3 m and a length of 6 m was joined to the second part of the chamber using a coupling.

A stainless steel door allows access to the chamber for carrying out any maintenance work required at a later date.

As soon as the two parts of the valve chamber were connected and installation complete, work began on joining the potable water tank. At the same time, the fitter contracted started installing the interior piping and the instruments.

Transport of the modules was carefully coordinated: the trucks were sent off on the 380 km route from HOBAS Austria in Wietersdorf to arrive in Karlstetten just in time. In addition, HOBAS also provides the hoists and ropes needed for joining the pipes.

The heaviest modules were the two parts of the valve chamber and a simple truck-mounted crane was all that was needed to lift the parts weighing 6 tons each.

Within a period of eight hours, all the parts of the water tank were delivered and installed by only four of the contractor’s men. While the tank pipes were backfilled on the outside with crushed stone the next day, the fitter finished the piping work inside the tank.

The project was thus completed and the tank ready for use in only two days.