Tunnelling has now been completed on the western branch of the main trunk sewer of the Doha South Sewage project.
The 5km sewer stretches from Al Thumama to Salwa Road through to the Abu Hamour area of the city and will make up around 30% of the total length of the main tunnel. The tunnelling works took just under a year and averaged around 13.7m per day.
The western branch is one of three main tunnels forming the main trunk sewer of the Doha South Sewage infrastructure project, and will carry sewage flows through fewer pumping stations to the existing Doha South Treatment Works. Around 20 old pumping stations will no longer be needed when the project is completed.
Using a TBM named “Al Zubara”, one of two TBMs designed specifically for the project, excavation works were completed using the Earth Pressure Balance (EPB) tunnelling technique at a depth of between 30m and 40m.
Speaking at the breakthrough, Qatar’s Public Works Authority (Ashghal) said it was still making progress in all its roads, expressways, buildings projects as well as the infrastructure and drainage projects that are being carried out deep underground.
When completed the 3m diameter main trunk sewer will be constructed using pre-cast segments - six segments to build one concrete ring of the tunnel – and use a total of 13,537 concrete rings.
The project includes the construction of seven lateral interceptor sewers with a total length of about 24km, which will move flows from areas in the centre of Doha to the main tunnel.
In addition 11 shafts will be constructed at a depth ranging from 20m to 40m to excavate the main tunnel. Four of these shafts will be excavated using a vertical shaft machine to minimise the impact and space of construction works within the city.
The main trunk sewer comprises of three branches; Eastern, Western, and Northern – a total length of 16km. The Eastern branch extends for about 7.5km from Al Thumama to Old Airport area, passing through the E-Ring Road, The Northern branch extends for about 4km from Al Thumama to Rawdat Al Khail area, through Al Najma area.
All the tunnelling is expected to be completed by the end of this year with the project completed finished in early 2019.
The project is a joint venture between Travaux Publics and contractor UCC, with CH2M as the project consultant.