The consortium of Colas Alterra and Alisca Bau was awarded the pressure line reconstruction works in connection with modernisation of the Tolna wastewater treatment plant.

The project prescribes the construction of D110 – D315 pressure lines on an aggregate length of 13181 m. However, the rather short pipe sections in question are scattered all over the town. The primary goal of their construction is to reduce odours and facilitate the transfer of the agglomeration’s wastewater to the treatment plant.

Available soil-mechanical data suggest that pipe laying is to be carried out in fine sand formations – consequently, no bedding material is necessary.

With continuous ditch digging and slipform technology, pipe construction is performed under laser level guidance, while the width of ditches is significantly lower in comparison with conventional methods. Due to narrow ditches, topsoil removal is rendered unnecessary, pipe laying is feasible without interruptions, and no work trenches remain open during the construction period.

The welding took 42 days with a daily output of 165 m of pipes, and we laid 300 m of pipeline each day over a 22-day-long period.

The work trench is less than 40 cm wide, which makes for a narrow work site, resulting in the minimisation of damages to surrounding vegetation. Due to the fast progress, treading damage is also kept down, and it becomes possible to hand over the area quickly – both imply cost-reducing factors for the clients.