A unique service package developed by Herrenknecht is assisting excavation of 3.3km of critical sewerage infrastructure under the Muslim holy city of Mecca in Saudi Arabia.
The Makkah (Mecca) Haram Sewer Line project presents a serious challenge from an operational support perspective since non-Muslims are not allowed under any circumstances to enter Islam’s most holy place of pilgrimage. Even the groundwater under Mecca is considered holy, which means that the infrastructure must feature a double-lined protection system to provide an extra failsafe against sewerage coming into contact with it.
To get around the problem of servicing the drive without the benefit of being able to supply personnel on site, German TBM manufacturer Herrenknecht – which is supplying 2 x 3.15m EPB microtunnelling machines to the National Water Company of Saudi Arabia for excavation of two alignments of 1.8km and 1.5km – has set up a tailor made service package that includes a real-time remote monitoring system set up at the company’s headquarters in Schwanau, Germany.
Machine operators from Herrenknecht are supporting the advance around the clock from a duplicate control cabin that has been set up in Germany and which is fed live data from the jobsite in Mecca. The TBM itself, meanwhile, is being operated in the ground by engineers from the Saudi Binladen Group, which holds the tunnel excavation contract.
Assistance from Herrenknecht for what is a challenging drive that features a tight curve radius would normally have been provided on site, but although special advance training has been given to the Muslim machine operators on how to negotiate the drive, the remote cabin set-up enables a further level of service.
“We have to work under time pressure in tight curve radii under Mecca’s busiest ring road and through holy groundwater,” explained Ibrahim Balaban, General Manager of the Tunnelling Division of the Saudi Binladen Group Saudi Arabia.
In some locations the curve radius is as tight as 80m. To ensure the total impermeability of the holy groundwater to the sewerage that the new infrastructure will help dispose of, a segmental lining system is being installed with two sealing profiles and an HDPE inliner to provide additional protection.
The project has recently been honoured with a German Society for Trenchless Technology (GSTT) Award in the International Project category.