New Water Line, overall reconstruction and extension of CWWTP, Prague

The subject matter of the public contract was performance of the project “Total Reconstruction and Extension of the Central Waste Water Treatment Plant (CWWTP) in Prague, Císařský ostrov, Construction No. 6963, Stage 0001 – New Water Treatment Line”.

The works were divided into the following stages:

1. Designing services (incl. engineering and related services) including preparation of complete design documents necessary for applying for a building permit for construction of the new water treatment line;
2. Designing and engineering services in order to obtain a building permit in force for construction of the new water treatment line, a permit of discharging the waste water into the surface water, a decision on putting the new water treatment line into trial run, final approval of the building including preparation of the required documents and carrying out all activities in order to obtain the necessary permits;
3. Complete construction works and technology on the new water treatment line including operation of the new water treatment line in Stage A of the trial run;
4. Operation of the new water treatment line in Stage B of the trial run.

The concept of the waste water treatment plant itself is interesting – it does not disturb the environment of Trója at the zoo with high reinforced concrete structures, which would protect the CWWTP against floods. According to the aesthetic requirements, all tanks of the new water treatment line will be placed underground, covered with a reinforced concrete floor slab and the final protection of the water treatment function will be ensured by a watertight closing of all areas of the line. This way, the operation of the CWWTP will be protected up to a twenty-year flood flow rate on the Vltava River. A park is to be built over the floor slab later on.

There are higher demands on protection of the structures against upward hydrostatic pressure from the Vltava River and the waterway. In the closed area of the waste water treatment line, there is a high risk of creation of an aggressive sulphuric acid, which can have a negative influence on the concrete surface of the tanks and on heath of the service staff. The upward hydrostatic pressure issue will be resolved by anchoring the bottom of the tanks into the subsoil and the effects of creation of the sulphuric acid will be suppressed by building a sophisticated ventilation system and use of special concrete.