Qatar public works authority Ashghal has commenced excavation of a 10km outfall tunnel, as part of Mesaimeer Pumping Station and Outfall project that started in May 2018, to provide a solution for the discharge of surface and storm water in the country.
Ashghal inaugurated the operation of the tunnel-boring machine (TBM) that will be used for the excavation.
The tunnel will be excavated at a depth of 15m below the seabed and about 3.7m in diameter.
The excavation will be carried out using a TBM that uses Earth Pressure Balance (EPB) technique and is designed to operate in a range of ground conditions in Qatar, and with the variable geology along the tunnel.
The second phase of the project includes a pumping station with 10 pumps and auxiliary facilities. The pumping station will be located at the end of Mesaimeer Tunnel south of Hamad International Airport and will operate at a capacity of 19.7m³ per second.
It is intended to pump water from Mesaimeer Tunnel, which was completed in 2016, to the new outfall tunnel.
The project is intended to decrease the surface water level and reduce pumping costs in construction projects around the country and will also preserve the foundations of buildings, and reduce land subsidence due to rain.
The project has been designed to preserve the marine environment, as the water complies with the environmental assessment standards, and will be discharged 10km off-shore.
Excavation works of the outfall tunnel and the construction of Mesaimeer Pumping Station are scheduled to be completed by the fourth quarter of 2021, at a total cost of about QAR920m ($253m).
A joint venture between Hamad Bin Khalid Contracting and PORR Qatar Construction is implementing the project. Mott Macdonald has been appointed to provide project management services, which will oversee the design, implementation and operation of the project.
The contractor will maintain and operate the project for a period of at least three years.
The tunnel extends below the F-Ring Road for 10km with a depth of about 30m below the ground surface.
The main tunnel is linked to the existing and planned drainage networks in the areas and will collect and discharge surface water from 170km² of catchment area, as it is connected to rain water drainage networks in 43 vehicle tunnels.
Image: Group photo during the commencement event of Mesaimeer outfall tunnel excavation. Photo: Courtesy of Ashghal.