In the course of the modernization, Doha has great plans for its underground. In a first step, 21 Herrenknecht TBMs created 112 kilometers of metro tunnels. Now construction of a new sewage system has begun. IDRIS, Inner Doha Resewerage Implementation Strategy in short is the name of the plan to renew Doha‘s wastewater system from scratch. More than 100 kilometers of sewerage lines are planned. “The old system could only transport sewage out of the city by means of numerous pump stations – and was increasingly reaching its limits,” says Jamal A‘bed, Head of Tunnelling at the Qatar Trading & Contracting Group, in charge of the construction of 24 kilometers of sewerage lines beneath the densely built-up old town. Eight microtunnelling machines from Herrenknecht have been in operation since March 2017 to build sewers with inner diameters between 40 centimeters and more than two meters.
“Competent limestone, groundwater and existing sewers and pipes are a challenge for us and require a first-class tunnel machine,” says Jamal A‘bed. “We have been working with Herrenknecht for a long time and know the advantages of AVN machines: they perform excellently even under difficult conditions and can be precisely controlled thanks to an electronic laser guidance system. With them we are on the safe side.” In addition to an extensive sewage network, IDRIS also includes a new central wastewater disposal line up to 62 meters deep, which will gravity feed to a treatment plant outside the city. “The new sewer system will make Doha fit for the future,” says A’bed.