Acta Scientiarum Polonorum

Abstract: The main aim of the investigations was to analyze hydraulic flow conditions of a vacuum sewage system making a lot of problems during its exploitation and to propose corrective action which should be taken to eliminate these problems. The scope of the investigations encompassed a vacuum sewage system built in a village Starawieś nearby Warsaw. The paper presents the analysis of the obtained results of the investigations of negative pressure changes along the length of the vacuum collector pipeline with diameter of 225 mm, in conditions of technical exploitation of the vacuum sewage system. Negative pressure measuring devices were distributed in six determined points (ferroconcrete wells with ISEKI interface valves) along the length of the vacuum collector pipeline. The measuring devices measured pressure changes every minute, by 24 hours per day, for several days. Changes of the negative pressure in vacuum sewage systems depend on the frequency of opening of interface valves and on the negative pressure in a vacuum container. In order to let the interface valves open, the negative pressure in vacuum sewage pipelines cannot be lower than –20 kPa. The analysis of the obtained results of the investigations allowed to define the causes of malfunctioning of the vacuum sewage system. The main cause of the problems was that the passages of the vacuum collector pipeline under the national road No. 62 were built contrary to the design. After reconstruction of the aforementioned passages according to the design and after proper adjustment of opening times of the emptying valves, the tested vacuum sewage system operated properly.