Dubai: From Creek to Canal
Its been several decades in the making but finally the long-held ambition of extending the historic Dubai Creek back to the Arabian Sea has become a reality. The achievement marked the realisation of a dream of Sheikh Rashid bin Saeed Al Maktoum one of the principal architects of the United Arab Emirates (UAE) 45 years ago and the late father of Sheikh Mohammed bin Rashid Al Maktoum, current Prime Minister of the UAE and Ruler of Dubai.
The first phase of the canal was completed more than a decade ago at a cost of AED 1bn and extended 9 km from Ras Al Khor through Business Bay to Sheikh Zayed Road (SZR). Like other big projects at the time, completing the final 6km stretch of the canal was put on the back burner while Dubai staged a recovery from the global financial crisis of 2008/9. But two years ago the project finally got the green light and in November the waterway was inaugurated in a spectacular ceremony overseen by Sheikh Mohammed.
Belgian contractor BESIX through its local venture Belhasa Six Construct was entrusted with the bulk of the works related to the new portion of the canal, which has turned a large part of central Dubai into an island. Jean-Pol Bouharmont, deputy general manager of Six Construct for the UAE, Oman, Qatar and Bahrain, was heavily involved in the process, especially during the final month to ensure it was delivered on time and to the specifications of the client The Roads and Transport Authority (RTA).
The contractor was awarded two main packages of work. The first involved diverting all the underground utilities and carrying out canal excavation wherever possible while it waited for another contractor to build the bridges over the main canal crossings – SZR, Al Wasl Road and Jumeirah Beach Road. The second package involved treating the water in Business Bay – which had become hyper saline over a 10-year period – before releasing it safely back into the sea.
The original creek extension was stopped with a series of utilities not diverted, Bouharmont says. In fact there was not just one lagoon in Business Bay but a series of them separated by bunts where the existing services were still in place. Due to a combination of evaporation, the tide and the dewatering of all the new buildings in the area (the dewatering was discharged into the lagoons) the water became highly saline over time. The biggest lagoon was more or less white as it was really hyper saline.
Carrying out the water treatment package was quite challenging in terms of how to dilute the water to an acceptable mix before opening the canal, especially on the creek side. Six Construct pumped the hyper saline water all the way from the lagoon up to a mixing basin near a newly created peninsula at Jumeirah where it was blended with seawater to reduce the salinity before being discharged into the sea. The whole process took two months with another month to pump normal seawater back into the lagoon using a pair of 800mm pipes laid on the canal bed.
This second package of work was awarded quite late in January 2016, where we had nine months to divert the services in Business Bay area, removing the bunts, pumping and mixing the seawater and then pumping seawater back into the lagoon, says Bouharmont. Then step by step the bridges were completed between April, for the first one, and July for the last one over SZR and we were able to excavate below the bridges and finally connect the canal to the sea.
The final stage of excavation could only take place once the bridges were installed on top of the huge pillars holding them in place. The distance from the bridge to the bass of the canal is around 12 metres and each pillar goes a further four metres below ground level. Around 50,000 m3 of earth was excavated from beneath each bridge but at this point removing the earth had become quite straightforward. Because the rest of the canal was already excavated, construction traffic could travel along the canal bed to the artificial peninsula built using the excavated earth.
There was quite a lot of traffic management during the two and a half years but that last part was not so difficult, Bouharmont explains. More difficult was installing the block work for the quay walls below those bridges. We got those areas quite late in the contract period and we had to be ready to expedite the work. We even coordinated with the client and the other contractor, especially on SZR bridge, to work on part of the quay walls while they were doing the foundation of the bridge. We didnt wait for the bridge to be completed before building the wall.
The quay walls were made using precast concrete blocks weighing 40 to 50 tonnes each. Every night during the construction period 30 to 50 blocks at a time were made in a special facility in Warsan, depending on the progress of installation. There is a ten metre wide promenade either side of the canal after which its safe to excavate to build alongside the canal.
You would have some shoring to do but you can excavate without any problem although there will be some dewatering during construction, he says. Basically you are building a huge brick wall and then back filling behind the quay walls with some rock. Technically it was not so challenging building quay walls. The challenges were more involving traffic management and trying to minimise disturbance to the environment because its an area where you have a lot of villas. You have an extremely tight schedule but at the same time you have to try not to disturb too much during the night. But the challenge was more to do with traffic sequencing because of the bridges and diverting existing utilities.
The latter involved recreating new networks for all the underground services sewer lines, electricity, water pipes, telecoms, etc that had previously passed through the site of the canal. The relocation of these services was a laborious process that took two years before excavation could begin. Tunneling was used where possible to minimise the impact on traffic and excavations.
Six Construct has plenty of experience doing some of what it was tasked with on this project while other elements were new. Its a unique project for sure. But its a mix of things we have done in different environments. Ive been here for 20 years and Ive always had at least two ongoing projects building quay walls with the same technique. So thats nothing special. Its more that it involved building in a heavily congested environment. But dealing with the hyper saline water is unique and it was necessary to investigate what would be the best solution. We had part of the expertise in house but for the pumping and mixing we used a specialist contractor.
Another major challenge only came about very late in the process. Due to design issues, Six Construct was given the green light to proceed with a very significant portion of the work construction of three pedestrian bridges and the canal promenades in the last six months, leading to a logistical headache to complete the job on time.
It was here that Bouharmont became deeply involved. Part of those bridges were executed while the canal was already flooded so we had to build temporary platforms over the canal to be able to build the bridges. There was a lot of sequencing into those bridges which are also technically quite challenging. When you see them now they are quite iconic. We used specialist sub-contractors to fabricate them but we had to help erect them.
With this job under its belt Belhasa Six Construct says it is ready to take on the next challenge for the RTA, which has been a regular client for the past 20 years. Among other projects, the contractor has delivered Business Bay Bridge, Garhoud Bridge and is building the bridge to Deira Islands. It also completed work on the Dubai Tram two years ago.
Olivier Crasson, executive vice president, confirms Belhasa Six Construct is tendering for infrastructure work in the run up to Expo 2020. The first packages for infra work are on the market and some have been awarded so we assume that the quantity of work related to Expo 2020 will increase, probably in 2017. But at the moment there is still not too much on the market.
Belhasa Six Construct is also experienced in another fast growing sector of the Dubai construction sector, having recently completed work on Legoland, part of Dubai Parks and Resorts. In fact it also worked on Ferrari World in Abu Dhabi and is carrying out an expansion of the theme park. The company says it is in discussion for more work in the theme park arena.
The Canal in Numbers:
– 3.2 km long
– 80m to 120m wide
– 4m deep
– 3 road bridges and 3 pedestrian bridges
– 250,000 m2 of area reclaimed on the sea
– 800m of new beach along reclaimed area
– 2.8 million m3 of excavation
– 9,400 concrete blocks
– 27,000 m3 of concrete for diaphragm wall