Deep Sewer Tunnel

Name of Project:

Deep Sewer Tunnel

United Arab Emirates

Abu Dhabi Sewerage Services Company (ADSSC) Abu Dhabi Water & Electricity Authority (ADWEA)

Total value:
€325 million

Construction period:
September 2009 (T-02) – December 2010 (T-03)

The project involves the construction of two out of three lots of the STEP Programme (Strategic Tunnel Enhancement Programme), featuring the construction of a tunnel approximately 40 km long which will be designed to collect the wastewaters of the island and mainland of Abu Dhabi by means of gravity and direct them to the treatment plant located in Al Wathba.

The works consist of the construction of 25 km of the tunnel with an excavation diameter of approximately 7 metres and 10 access shafts with depths varying between 40 and 80 metres.
The project, which is particularly complex from a technical and organisational point of view, involves the simultaneous use of five TBMs (Tunnel Boring Machines) at earth pressure, capable of excavating and at the same time coating the tunnel with prefabricated concrete.
It is the first time that this sophisticated, mechanised excavation technology has been used in Abu Dhabi.
Both the hydraulic tunnel and the access shafts will be covered with a special membrane which will guarantee the concrete structures total protection from the aggressive ambient and will last at least one hundred years.

ContraCT t-02 t-03
Underground excavations 535,000 m3 356,000 m3
Concrete 185,000 m3 125,000 m3
Steel reinforcement 3,700 tons 2,465 tons
Metal fibres 3,150 tons 2,100 tons
Prefabricated blocks 11,071 n° 7,381 n°
HDPE membrane 248,000 m2 163,350 m2

Last update: 07/09/2016

OTHER PROJECTS: United Arab Emirates