- The three major tunnelling lots of the 45km-long gravity-fed interceptor sewer of the US$3 billion Inner Doha Resewerage Implementation Strategy (IDRIS) in Qatar are awarded to joint ventures comprising two of Europe’s leading tunnel construction companies.
Table 1. IDRIS contract packages Lot Contractor Value (€) Length i.d. North
Buoygues/Urbacon 240m 16,000m 3.0m South
Buoygues/Urbacon 310m 14,000m 4.5m Central
265m 14,700m 4.5m
- TunnelTalk understands that a total of six slurry/EPB machines, ranging in diameter between 3m and 4.5m, will be procured for excavation of the central spine of the Qatari capital’s largest ever sewerage mega-project.
- Construction of the main interceptor – which is similar to neighbouring Abu Dhabi’s STEP project – is divided into three design-build lots: north, south and central. The north and south lots, which together total 30km in length, to i.d.s of 3m and 4.5m, are awarded by the Qatar Public Works Authority, Ashghal, to a joint venture headed by French construction giant Buoygues, for a combined contract sum of €550 million. Its partner is local contractor Urbacon.
- The 14.7km central section, with an i.d. of 4.5m, is awarded to the Hochtief/Al Sraiya Strabag for Roads and Infrastructure/Petroserv joint venture, with the German company holding a 45% share of the €265 million contract value. Owner design is by CH2M Hill.
- A Hochtief spokesman said: “For constructing the 14.7-kilometer-long tunnel [of the central lot], two TBMs will be used. After installation of the tunnel’s outer lining an inner lining will be added to protect the concrete from the aggressive gases that form part of the geology. This will be achieved by means of the installation of an HDPE membrane, thus ensuring a project life of 100 years".
IDRIS design features 45km interceptor sewer, 70km of lateral sewers and a 70m deep underground pump station
- He added: “In addition to the tunnel, shafts up to 45m deep will be built, some of which will serve as connectors to other IDRIS construction contracts.”
- Jean-Philippe Trin, Deputy CEO with responsibility for Bouygues Travaux Publics, said: “For this ambitious project we have developed an innovative technical solution that will enable us to address the customer’s concerns effectively and fully meet their expectations.”
- In recent years the Qatari capital, which is due to host the 2022 Soccer World Cup, has experienced sustained population growth that has necessitated the redesign and expansion of its sewage system. More than 70km of newly-constructed lateral sewers of i.d. 400mm-2,400mm, to be constructed using microtunnelling and pipejacking techniques, will connect with the IDRIS interceptor. Once completed, in early 2019, the system will cover an area of 680km2.
- Project scope also includes construction of a terminal pump station located 70m under the ground, as well as construction of a new sewage treatment works plant to serve Doha South, and with an initial capacity of 500,000 litres/day.
- The IDRIS project is just one of a number of mega-projects currently under construction in Doha.
- Last year Salini-Impregilo of Italy, which also worked on the now-completed Abu Dhabi STEP project, completed TBM excavation of Phase I tunnelling on Doha’s Abu Hamour Southern Outfall Project, aimed at flood prevention following heavy rainfall events. Two Herrenknecht EPBMs of 4.47m diameter broke through in September last year (2015) following drives of 5km each.
- Meanwhile excavation continues on the city’s multi-billion dollar new metro system.
EPBM breakthrough for Qatar flood prevention - TunnelTalk, September 2015
Soft ground challenge for Doha EPBMs - TunnelTalk, February 2015
Arabian aspirations for greater integration - TunnelTalk, December 2013
Final tunnel awards on giant STEP project - TunnelTalk, January 2012
Peter Kenyon, TunnelTalk
- After years in the planning, prequalifiers are called for the US$3 billion Inner Doha Resewerage Implementation Strategy (IDRIS) design-build sewerage project in the Qatari capital, Doha.
- The project, for Qatari Public Works Authority, Ashghal, comprises at its heart a deep gravity sewerage system similar, but larger in scope, to the STEP project in neighbouring Abu Dhabi. The work is to be subdivided into six construction packages.
113km of new tunnels required for IDRIS
- Package 2 is for a TBM-driven main trunk sewer of approximately 40km in length, at depths of between 24m and 59m. Concept design has been completed by CH2M Hill, and calls for an i.d of between 3m-4.5m with a segmental lining and a secondary corrosion protection lining.
- Package 1 is for approximately 73km of 400mm-2,400mm diameter lateral interceptor sewers to be installed at depths of between 4m and 40m using microtunnelling and pipe jacking techniques. Ground conditions across the entire project area are expected to comprise weak rock with a maximum strength of 45 MPa, with a high groundwater table. Use of EPB or slurry TBMs is anticipated.
- Other packages include construction of a terminal pump station at a depth of 70m and with a design pump capacity of 12m3/second, a new sewage treatment works (both on a design-build-operate basis) and a treated sewage return system.
- Contract awards are expected in the first quarter of 2014, with a scheduled start of operations set for 2019. At an IDRIS project briefing in January this year (2013), nearly 400 companies expressed an interest in the project, one of many with a large tunnelling element in the fast-growing Qatari capital that will host the 2022 Soccer World Cup.
- On the construction side, strong international interest was shown by companies including: Balfour Beatty; Bouygues Construction; China Railways; Dragados; Ferrovial Agroman; Gamuda; Habtoor Leighton; Hochtief; Hyundai; Samsung; Impregilo; Joseph Gallagher; Obayashi; Odebrecht; OHL; Porr; SNC Lavalin; Strabag and Zublin. TBM manufacturers in attendance included Robbins, Herrenknecht, Caterpillar and Hitachi.
Foul sewage overflows in Doha
- The IDRIS project aims to eliminate as many existing foul sewage pump stations as possible and provide for an initial capacity of 500,000m3/day, rising to three times that at peak. Population in the city is expected to grow by 1 million people over the next few years, and current levels of foul sewage flooding at more than 20 locations in Doha are expected to get worse as population grows and other infrastructure constuction ramps up.
- A number of international companies are well placed to win IDRIS contracts based on their involvement on Abu Dhabi's similar Strategic Tunnel Enhancement Program, which is also being managed by CH2M Hill. Impregilo of Italy is currently the main tunnelling contractor on two of the three main tunnel packages on that project, while Samsung of Korea holds the third package. A total of 8 TBMs (three Kawasaki and five Herrenknecht) are completing the total 41km of trunk sewer, while Brazilian contractor Odebrecht is constructing the US$572 million pump station. Strabag subsidiary Zublin of Austria is excavating 50km of interceptor tunnels of between 500mm and 3,100mm diameter.
- Additionally, Impregilo is selected as main contractor for another US$100 million 9.5km storm water drainage tunnel in Doha, a project that will requite two TBMs of 4.5m diameter.
- Qatar is also constructing a new four line metro system in time for the World Cup, with the first tunnel contract for the Red Line North also awarded to Impregilo. Other construction packages are due to be awarded imminently.
Final tunnel awards on giant STEP project - TunnelTalk, January 2012
Qatar begins Doha metro tunnel awards - TunnelTalk, April 2013
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