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STEP technology is changing the game in the MENA region | |
| Nitin Konde |
The waste water infrastructure in Abu Dhabi has had its capability greatly increased thanks to the Abu Dhabi Strategic Tunnel Enhancement Programme (STEP). A new deep gravity sewer pipeline and a network of link sewers leading into the tunnel will transport Abu Dhabi's primary sewage flows to a new treatment works located outside the city.
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The new 45-kilometer deep gravity sewer pipeline will be built. Along its length, its width shifts from 5 to 6 or 8 metres. Seven earth pressure balance (EPB) tunnel boring machines (TBMs) were used to dig the tunnel, with each machine beginning its work in one of seven deep tunnels. Prequalification for the project began in August of 2008, and building began in 2009.
Plan Abu Dhabi 2030 is a comprehensive strategy for expanding Abu Dhabi to meet the needs of its anticipated three million residents by the year 2030, and the current project is a vital component of that strategy. In order to irrigate crops, the initiative will provide 15 cusec of greywater. As of the end of February 2013, 33 kilometres (km) of the tunnel's planned 41 km had been tunnelled. Nearly 450,000 m3 of effluent is being treated every day at Abu Dhabi Sewerage Services Company. When the STEP project is completed, it will have the capacity to process 800,000m3 of wastewater annually.
What exactly is STEP Technology
The concept of the proposed Strategic Tunnel Enhancement Programme (STEP) system was to use a series of link sewers to intercept flows from existing gravity sewers upstream. The idea was to transfer the flows by gravity into the deep tunnel sewer, thereby providing relief to the existing main collector system. These flows will again be transferred by gravity via the deep tunnel sewer to centralized wastewater treatment facilities strategically located at Al Wathba, at the southern end of the metropolitan area of Abu Dhabi.
Contract T-01 is one of the three packages of the Strategic Tunnel Enhancement Programme (STEP) deep tunnel sewer, linking the northern part of Abu Dhabi Island to the mainland. Package T01, consisting of 16.1 km long Main Tunnel with 4 m diameter at depths ranging from 20 m to 34 m below ground level, is the longest tunnel of the project. The works included four operating shafts and three access shafts. STEP was implemented to establish a tunnel that would cater to the immediate, short and long-term needs of Abu Dhabi's wastewater and drainage issues. It is believed to be one of the longest gravity-driven wastewater tunnels in the world. STEP consisted of the following infrastructure improvements:
The Abu Dhabi Sewerage Services Company (ADSSC) is currently managing the STEP project by constructing a huge gravity-driven hydraulic wastewater network. Former Managing Director of ADSSC, Alan Thomson said, “this centralized system with a deep sewer gravity tunnel was first used in Singapore”. His company has “adopted a similar approach but with changes to match the needs of Abu Dhabi and the UAE as a whole”. This involves “introducing the newest technologies available in the industry”.
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Abu Dhabi Sewerage Tunnel Construction
Tunnel boring tools are used for the excavation, and precast concrete sections are used for the tunnel's casing. A special membrane is being installed to safeguard the concrete portions of the hydraulic tunnel and the access shafts. The projected lifespan of the passageway is one hundred years.
The primary tunnel was built in three stages labelled T-01, T-02, and T-03, while the link sewers and pump station were built in two stages labelled LS-01 on Abu Dhabi Island and LS-02 on Abu Dhabi main land.
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In September 2009, Impregilo Group was given the contract to build the 15-kilometer-long T-02. Using an excavated diameter of 6.3m and six access tunnels dug to depths of 40m to 50m, the tunnelling was successfully completed.
In addition, in November 2010, a contract to build 10.5km of T-03 was given to Impregilo Group. Four access tunnels were dug out to depths between 60 and 80 meters, and excavation had a seven-meter diameter.
South Korean company Samsung C&T Corporation was responsible for tunnelling section T-01 of the main tube. Kawasaki Heavy Industries provided three tunnel boring machines (TBMs) for the project.
The finishing of the 25 km tunnel segment by Impregilo in January 2013 marked a significant milestone for the project. In order to complete the tunneling, five Herrenknecht TBMs were used.
To Zublin goes the contract for building the connecting sewers LS-01 and LS-02. Pipe jacking was used to build the sewage system. About 247 shafts need to be dug with widths between 200mm and 2,800mm for the LS-01 project to be completed. Building LS-02 requires 95 shafts and excavation works with widths from 200mm to 3,100mm.
In the first quarter of 2023, Ashgal in Qatar plans to hold a tender for drainage pipes
The Drainage Tunnel Works at New District Doha project is scheduled to receive its design and construct tender from the Qatar Public Authority (Ashghal) in the first quarter of 2023. The assessment of the prequalified bids has begun. According to a source familiar with the project, the Authority will ask the winning bidders to take part in the main construction tender.
According to the source, the main building tender will be issued around the middle of the first quarter of 2023, and the contract will be awarded around the middle of the third quarter of the same year. On July 7, 2022, Ashghal put out the EOI asking for expressions of interest. The original proposal due date of August 14 was extended to September 25 and then again to October 23 of the same year.
In accordance with Qatar's 2030 Vision and the Integrated Drainage Master Plan, the main goal of the strategic projects in New District Doha is to provide long-term future stormwater management infrastructure.
Storm and ground water flows from ongoing and planned projects will be channelled through strategically placed pipeline systems and eventually collected at strategically placed pumping stations. After that, it will either be pumped out to sea through a marine outfall or kept in a lagoon on land.
There will be four separate contracts for this project: Marine pumping station and marine outfall tunnel (Contract 1), eastern tunnels (Contract 2), western tunnels (Contract 3), and inland pumping station and inland marsh balancing lagoons (Contract 4) are the individual components of the overall project.
The ancillary structures consist of an office building, an electrical and control building, two security rooms, a workshop and storage utility building, a standby power generator building, a fire pump house, a TSE pump house, an inland pumping station, a coarse screen with a grabber mechanism, and a handling facility for the sewage overflow.
The construction project's preliminary contract adviser and design architect is Halcrow (Consulting Engineering & Architects). According to the first authority, Gulf Laboratories Co. has been hired as the geotechnical provider.
According to him, the project is expected to be finished in the first quarter of 2026 and will cost around $400 million.
This Dubai water pipeline has a 100-year storage capacity
The municipality of Dubai announced that a recently finished deep tunnel has the capacity to store water for the next century.