Dubai advances strategic sewerage tunnels expansion with Phase II bids

The authority said requests for proposal have been issued for the Phase II Links Package of the project, which is designed to connect outlying catchments to the main deep tunnel system through a network of secondary tunnels and associated assets. The package is expected to be delivered through a public-private partnership structure, building on the approach adopted for earlier components of the scheme.

The DSST programme centres on constructing deep gravity-driven tunnels to transport sewage to major treatment facilities, reducing reliance on pumping stations and surface pipelines. Once fully built, the system is intended to serve the city’s projected population growth for several decades while improving operational resilience and environmental performance.

People familiar with the procurement said the Phase II Links Package will involve significant underground works, including long-distance tunnelling, shafts, and tie-ins to existing infrastructure, alongside mechanical and electrical installations. Developers have been asked to submit technical and commercial proposals covering design, construction, financing, operation and maintenance over a multi-decade concession period.

Officials have framed the project as critical to Dubai’s urban planning strategy, given the emirate’s expansion into new residential and industrial districts. Wastewater volumes have risen steadily with population growth, tourism activity and industrial output, placing pressure on ageing networks originally designed for smaller catchments.

The DSST scheme was conceived to address these challenges by consolidating flows into deep tunnels, allowing gravity to replace energy-intensive pumping over long distances. Engineering assessments conducted during the planning stage projected substantial reductions in energy use and greenhouse gas emissions over the asset life, alongside lower operating costs and fewer service disruptions.

Market participants say interest in the Phase II package is expected to be strong, reflecting a global appetite among infrastructure investors for large, availability-based assets in stable jurisdictions. International contractors with tunnelling expertise are likely to partner with financial investors to meet the technical and balance-sheet requirements of the project.

The procurement comes amid a broader push by Dubai to use PPP models to deliver complex infrastructure while transferring certain risks to the private sector. Previous wastewater and water projects in the emirate have drawn competitive bids, supported by long-term demand fundamentals and transparent regulatory frameworks.

Under the DSST plan, multiple phases are being rolled out sequentially to manage construction risk and integrate lessons learned. Phase I focused on the main deep tunnel and initial connections, while Phase II extends the system’s reach to additional service areas. Later stages are expected to further densify the network as new districts come online.

Municipality officials have emphasised that environmental safeguards are central to the programme. The deep tunnel approach reduces the footprint of surface infrastructure, limits odour issues in urban areas and lowers the risk of overflows during extreme weather events. Treated effluent from connected plants is also intended to support reuse for irrigation and industrial applications, aligning with water conservation objectives.

Industry analysts note that the scale and technical complexity of the links package will require careful coordination with ongoing urban development and existing utilities. Detailed ground investigations, advanced tunnel-boring technology and digital monitoring systems are expected to feature prominently in bidders’ proposals to manage geological and construction risks.

The timing of the RfP issuance suggests the municipality is seeking to maintain project momentum while market conditions remain supportive. Infrastructure financing costs have fluctuated globally, but the emirate’s track record and credit profile continue to attract long-term capital from pension funds, sovereign investors and specialised infrastructure managers.

Contract award timelines have not been publicly detailed, though developers are understood to be working to submission schedules that would allow construction to commence following financial close. Once operational, the Phase II links are expected to significantly expand the catchment served by the deep tunnel system.