Wastewater Project of the Year
Strategic Tunnel Enhancement Programme, Abu Dhabi
What is it?
A tunnelling and sewerage project to connect Abu Dhabi city with the new wastewater treatment facilities at Wathba. The project involves the construction of a 41km deep sewer tunnel and 45km of link sewers, in addition to a major terminal pumping station. It is designed to transport average flows of 22m3/s (1.9 million m3/d) and peak flows of 39m3/s (3.4 million m3/d) to accommodate population growth up to 2030.
Who is responsible?
The Abu Dhabi Sewerage Services Company hired CH2M as programme manager to execute the AED6 billion (US$1.6 billion) project, with the deep tunnel works contracts delivered on time and on budget by Impregilo and Samsung C&T Corporation. The pumping station was designed by Mott MacDonald and built by Odebrecht.
What makes it special?
The massive tunnel project makes up part of Plan Abu Dhabi 2030, an urban development project. It is a deep gravity system which channels sewage from Abu Dhabi island through massive tunnels, helping to reduce odour and the chances of overflow during times of flash flooding. The ability to handle such immense volumes of wastewater is crucial to Abu Dhabi’s target of achieving 100% wastewater reuse by 2018.
The programme sets a new benchmark for the region, and minimised environmental impact and disruptions to the community through the use of trenchless technology and mechanised deep tunnelling techniques. The terminal pumping station is the largest of its kind in the world, and will allow 35 existing pumping stations to be decommissioned, freeing up valuable land for development.
Designed for a maintenance-free 100-year lifecycle, the new system will improve reliability, reduce operating costs, and mitigate CO2 emissions. Delivering the major portions of such a monumental project on time was testament to the team’s dedication, and all that remains now is local link connections before the STEP project can begin to transform Abu Dhabi’s wastewater handling abilities.
Distinction
Hong Kong Integrated Wastewater and Sludge Management
What is it?
Stage 2A of the Harbour Area Treatment Scheme (HATS) comprises the construction of sewage conveyance systems, the upgrading of the Stonecutters Island Sewage Treatment Works (SCISTW), and the upgrading of eight preliminary treatment works on Hong Kong Island, increasing treatment capacity to 2.4 million m³/d. This coincides with the commissioning of the world’s largest sludge treatment facility (2,000 tonnes/day) in Tsang Tsui.
Who is responsible?
HATS 2A was implemented by the Drainage Services Department (DSD), with Arup acting as consultant. A Biwater-led team completed the upgrade of the SCISTW – which features one of the world’s largest underground sewage pumping stations – while the Environmental Protection Department (EPD) appointed a Veolia/Leighton/John Holland consortium to design and build the STF.
What makes it special?
“Hong Kong” in Chinese literally means “fragrant port”, but the stench from the coastal waters of Victoria Harbour was threatening to deprive the city of its identity. HATS is an initiative to improve the quality of water in the harbour area, and the completion of stage 2A means that all sewage generated by five million residents either side of the Victoria harbour will be sent for treatment, instead of being discharged directly into the sea.
On its own, HATS would have solved one problem whilst creating another, by putting pressure on limited landfill space with the greater amount of sludge generated. The thermal-based STF plays a key part in the solution by incinerating the sludge to generate heat, which then drives a steam turbine to generate power, with any surplus being directed to the grid.
The water quality in Victoria Harbour has improved markedly, as has the quality of life for Hong Kong’s residents. Beaches have reopened, and recreational water activities – previously halted due to pollution – have resumed. The neat dovetailing of the numerous infrastructure components reflects a uniquely holistic and forward-thinking approach to municipal wastewater and environmental management.
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