Ring Rail Line – Protection Structures Against Aggressive Fluids

During the excavations of railway tunnel of Ring Rail Line ground water leakages containing ad-verse compounds were found under the airport area. The investigations showed that ground water at a minimum pH under 5 is acidic and contains antifreeze agents as ethylene and propylene glycols which have been used decades in aviation. In aerobic conditions the glycol based fluid forms alco-hols and organic acids, most relevant of them acetic acid and propionic acid. The fluid is a nutrient for microbes and enables their growth in a tunnel. The microbe growth forms also distinctive odour, which is undesirable at underground railway used by passengers.

To isolate harmful aggressive leakages protection structures were designed for all tunnel sections and station areas where adverse substances were detected. Leakage has been found to be corrosive to steel structures and erode to cement-containing structures so polyethane membranes were de-signed to install around the railway tunnel structures and all materials which can be in contact with glycol based fluids were chosen for aggressive environments.