The large-scale sewage treatment plant Czajka, situated to the northeast of Warsaw, is scheduled to be finished in December 2010 and this after only a two-year construction period. With a cleaning capacity of almost 450,000 cubic meters per day, designed for the equivalent of two million inhabitants, it will be the largest wastewater facility in Poland. Together with the Warsaw-located Warbud construction company, PERI's Polish engineers developed a cost-effective and comprehensive formwork and scaffolding concept that fulfilled all requirements regarding the best-possible concrete surfaces, short construction period, and a high level of onsite safety.

With its size and corresponding structural element dimensions, the Czajka plant has placed very high demands on site personnel and the formwork systems being used. On 600,000 square meters, which is equivalent to 80 football fields, a total of 120 complex individual structures have been developed. Depending on the purification stage of the sewage plant facility, the tanks vary in both form and height. In spite of the tight construction schedule, PERI has been able to supply the required large quantities of materials to the construction site on time through close collaboration with Warbud without any problems. The small number of different individual components ensured the construction progress could be accelerated. As a result, around 50,000 square meters of straight walls and 30,000 square meters of circular wall surfaces have been efficiently constructed.

System combination for high walls

For forming the 8- to 11-meter-high reinforced concrete walls, ranging in wall thickness from 20 to 75 centimeters, three wall formwork systems have been combined. Equipped with appropriate platform systems, these customized complete solutions offer maximum safety for the construction site team as well as fast shuttering times due to the formwork being moved as large-area complete lifting units from cycle to cycle. Reinforcement scaffolding provided an ideal addition to a safe working environment, and stair towers guaranteed optimal access to areas of operations.

Increase safety, reduce costs

For the straight wall sections, regulation-approved working platforms and access ways on all required levels have proved to be particularly advantageous. For this purpose, panel formwork with stipulated working platforms, ladder access, and guardrails were mounted to form complete liftable units. As pre-assembly takes place only once, construction site personnel saved on any subsequent additional time and effort for modification work.

In addition, the contractor used 24 girder wall formwork complete with a pre-assembled platform system. Here anchor positions and element connections can be reached without any risk, and safe working areas are available for the concrete work. The one-time-only assembly at the beginning and the dismantling at the end also ensured enormous time savings. This means the usual time-consuming handling of individual brackets and planking every time is no longer necessary.

A well-rounded solution

Construction of sewage treatment plants involves the forming of reinforced concrete walls with a range of different tank diameters. The formwork elements used can be adjusted quickly and easily onsite in order to match the required radius. The self-cleaning hexagonal thread of the spindles provides continuous fast adjustment. Through the extension splice, panels remained securely connected to each other even at an 8-meter height. Horizontal connections take place using an alignment coupler, which bridges infill areas of up to 10 cm thick with only one connection part. This reduces the number of individual components needed. Because the manufacturer plans and supplies formwork and scaffolding from one single source, time and resources have been greatly reduced on this project.

Environmental protection a sector with a future

In Poland, more than 1000 wastewater treatment plants must be built or modernized in order to fulfill European standards which take effect in 2015. With a price tag of more than 500 million Euros, Czajka is not only the largest sewage facility in the country, but it also is considered one of the most important environmental protection measures in Europe. As project completion has been carried out in two phases, this has ensured that daily operations also have continued during construction work.

Source: PERI GmbH