Dubai Municipality has announced the commencement of geotechnical works for a major sewage treatment project.

Expected to complete in 2022, the Dubai Strategic Sewer Tunnel Project will involve the construction of more than 70km of tunnels supported by approximately 140km of link sewers and pumping stations.

Parsons Overseas Limited has been appointed by Dubai Municipality as the engineering consultant for the project.

Dubai Municipality’s Drainage and Irrigation Department (DID) is reportedly proceeding with the site investigation programme, with Parsons engaging a company to drill 250 boreholes along the route of the new sewerage network. 

Read: Dubai to start work on $8.2bn sewerage project in 2019

The DID expects this programme to take up to nine months, Dubai Municipality said in a statement.

During this field work phase, truck-mounted rotary rigs will move to locations along the proposed route of the tunnel and link. The duration of stay at any single location will vary, depending upon drilling depth and in-situ testing requirements.

In general, however, drilling rigs are expected to stay at each location for two to five days.  The rigs will be equipped with drilling rods, drill bits, excavation tools, and various in-situ testing equipment.

Varied ground conditions are expected to be encountered along the proposed tunnel and link sewer alignment.

According to Dubai Municipality, detailed subsurface information is needed to develop a precise and accurate ground model along the entire route, which will assist in the design process and selection of appropriate tunnelling tools and technology. 

Upon completion of field work, the results of in-situ testing and laboratory analysis will be evaluated to provide advice on appropriate construction methodologies for the tunnels, link sewers, and shaft excavations, and to provide ground parameters that will enable engineers to produce cost-effective designs.

Dubai Municipality noted that the project will eliminate more than 100 pump stations around the city that currently transfer sewage to treatment plants in Al Warsan and Jebel Ali.

Eng Hussain Nasser Lootah, director general of Dubai Municipality, commented: “The sewerage infrastructure is part of the essential infrastructure of a modern city.

“To fulfil the city’s needs, Dubai has approved an integrated plan proposal to expand the existing sewerage system and improve the arrangements for sewage disposal by combining land-based sewage treatment and a deep tunnel sewerage conveyance system.”

Lootah added: “Since 2003, Dubai has experienced rapid population growth. In addition to a rapid change in population, there is an increase in residential communities where mixed use is gaining ground and residential areas are increasingly accommodating commercial, public, and mixed-use facilities.

“Thus, residential areas are affected greatly in terms of increasing density and overloading of existing infrastructure. The new sewerage system will serve the city for at least the next 50 years.  We want to reassure the local communities that they will not experience any disturbances during the initial exploration work.”