Wastewater drainage network: Working atmosphere’s analysis

Abstract

In the city of Beja, Portugal, there is an infrastructure for the conduction of wastewater for treatment, this infrastructure is subject to periodic and systematic rehabilitation and maintenan- ce and can still be used by authorities and even by other companies. Each manhole is a potential confined space with all the constraints and problems that they usually present. A thorough and systematic analysis of the atmosphere inside the manholes of the wastewater drainage system was made to know the respective risks and hazards to all subjects exposed, throughout the East part of the city, from the gases produced and in these installations. The data collection was carried out in two different periods when the network presented minimum flows in normal operation. The flows were considered minimum after the reading of the flowmeters installed in the measurement areas indicated it.