Site visit: Jewel of the Creek
HLG overseeing a truly impressive engineering feat in heart of Dubai
The Jewel of the Creek could be Dubai’s most unassuming construction site, nestled as it is between Al Maktoum Bridge and the Floating Bridge.
Though there has been a visible flurry of cranes at the site for over a year, little else has visibly emerged, except for those with a bird’s eye perspective, or a view from one of the nearby structures.
However, the reality is that the construction project underway at the site by the Habtoor Leighton Group is arguably the largest such undertaking on a single structure in the whole of Dubai.
Indeed, the colossal podium not only covers the entire 123,955m2 plot, but extends for four basement levels below grade, and all on a site immediately adjacent to the open water of the Dubai Creek – a situation that has required the erection of a cofferdam packed with a vast bulk of supporting earth.
HLG signed the $130m contract in February 2012 for the 28-month-long package, the seventh in the 2005-initiated construction, and still just a fraction of its estimated total budget of $820m.
The award also marked the reawakening of the project by its client, Dubai International Real Estate (DIRE) – a company managed by His Highness Sheikh Hamdan bin Rashid Al Maktoum, the Deputy Ruler of Dubai and the UAE’s Minister of Finance and Industry, after a number of years on hold.
At the time, the progress on the site consisted of the cofferdam, excavation and a distribution of 12,600 piles – the preparatory work for HLG’s scope in constructing the raft, retaining walls and substructure of the project.
The finished development resting on this labyrinth will be a massive waterfront complex, comprising a dozen 19-storey apartment buildings, three office towers, two luxury hotels, a recreation centre and a convention centre with a ballroom, as well as a marina and a slew of retail spaces for shops and restaurants.
HLG’s scope of work includes the embedded MEP works, the re-anchoring of diaphragm walls, pile cutting and trimming, waterproofing works and reinforced concrete works.
Since a considerable length of time had passed between the completion of the previous package and HLG’s scope for the site, there were initial concerns over the existing waterproof membrane around the site that warranted investigation. An assessment was conducted on behalf of the main contractor by Sika Engineers, a specialist in sealing and reinforcing, which determined that “there were no issues regarding the stability of the cofferdam,".
With this clean bill of health, HLG was ready to begin, and in March 2012 the project was joined by Yehya Harfouch, who headed the project as operations director.
In February 2013 he became overall projects director for Dubai, but he still spent much of the year occupied at the site offices of the Jewel of the Creek, alongside construction director Hassan Slim, in a testament to the overwhelming monopoly that the Jewel of the Creek held over HLG’s resources for much of the last two years.
The combination of the scale and pace of the work resulted in the breaking of several records for construction in Dubai, including a concrete pouring rate that peaked at 1,000m3 per day.
Harfouch says: “The record we achieved in this project is not only about the average rate per day, but in maintaining that rate of production for months, and peaking at 32,240 m3 in April 2012.”
The logistics work involved in transporting all of this concrete across the site was, alongside the issues presented by the depth and scale of the cofferdam, one of the key challenges on the project. For one thing, there was only one site entrance, a huge ramp descending from Baniyas Road down to the raft level.
According to Harfouch, this ramp “occupied an area equivalent to 15% of the buildable plot area, so it was always the case that at some point it would have to be removed in order for construction to commence in the same area”.
The majority of the ramp was planned to occupy the broad channel bisecting the project, and which, with only two built-up floors, would be faster to complete after rerouting the access.
The volumes of concrete required for the project also necessitated the operation of an on-site batching plant, but the only location for this was on a thin strip of packed earth between the cofferdam and the internal retaining walls of the project. As a result, the erection of these retaining walls became a top priority within the project programme.
“One of the key details was to have the retaining wall fully completed by the time we were 60%, or a year, through the project schedule, for the sake of the logistics and to eliminate the risk of any failure in the cofferdam from the Khor side, or of the diaphragm wall from the Baniyas Road side,” Harfouch added.
This progressive backfilling of the spaces between the cofferdam, diaphragm and retaining walls as the project developed eventually allowed the descent of a second access ramp from the space now packed at grade between the retaining wall and cofferdam into the project’s central channel from the creek side of the project.
Both before and after the retaining wall was in place, the sheer height of the adjacent cofferdam and body of water above the site continued to pose a specific safety concern for the project, and required a site-specific evacuation drill.
Harfouch is full of praise for Dave Leader, the health and safety manager, for giving the advice and recommendations that ensured such a safety-focused construction team.
He says: “The overall safety of not only this project but of all Habtoor Leighton projects is of the upmost importance, but the Jewel of the Creek in particular has a very dedicated safety team.”
To waterproof the raft and retaining walls subcontractor Essam Kabbani loosely laid a PVC membrane system, provided by Sika Engineers, in a compartmentalised system lined with injectable hoses and water stops to facilitate its ongoing control and repair by injection in all post-construction phases of the project.
Harfouch says: “This system was the perfect choice for such a project, since it is fast to install, highly resistant to acidic water and above all having a service life of 20 years.”
All four of the basement levels will be used for parking, which “although very costly to construct and protect”, according to Harfouch, remained “the perfect decision given the huge scale of the project and its location in a highly congested area”.
Once the erection of columns and slabs for the four basement levels within the confines of the retaining walls was in full swing, the logistical demands grew, and a total of 23 tower cranes were erected to keep all manual handling of building materials to a minimum.
Even so, during the project’s peak months of June and September 2012, HLG was handling the operations of an average of more than 2,800 labourers on-site.
Harfouch adds: “There are a lot of challenges on this project and we have mentioned only some of them – there were also technical considerations in deciding the location of the site’s construction joints, and the precise sequence for the simultaneous pouring and closing of all the shrinkage strips in order to fulfil the structural specifications required for the buildings that will sit above.
“In addition to this, the dewatering work was very challenging; to run it, maintain it and protect it, and there are also challenges with regards to the nature of the soil and its effect on a great number of the pile heads.”
The cofferdam will be removed only after completing phase two of the project, during which the backfill between the cofferdam and the retaining walls will continue to be utilised as a platform for the construction’s logistics and storage.
However, Harfouch explains: “The inundation of the site will of course be a very delicate operation and will be carried out by a specialist, but the water will only be going along its intended route.”
Dubai Municipality updated earthquake codes in May 2013, from a rating of 2A to 2B, for buildings above 10 floors. Harfouch notes that the designs of the future towers are being tested against modifications, but that the original design for the substructure was more than sufficient to meet the new code, without the need for any changes.
He adds that HLG’s performance on this project could not have been achieved without the contributions of all of the parties involved, including Kling Consult and Kieferle Partnership (KCKP) as the engineering consultant, and all of the subcontractors on the waterproofing, as well as the suppliers of the steel, concrete and other materials.
“The communication between parties was excellent and swift action and commitment was there from start to finish,” he says.
Moving forward, Harfouch says the performance of both HLG and KCKP on the project will set both parties in good stead for the round of bidding for the next package, which will be awarded through competitive tender.
HLG is also now busy with the $1.4bn Al Habtoor Palace, which has a 28-month schedule due for completion in 2016, and the more recently-announced $3bn Habtoor City, a 929,000 m2 complex of three towers and three international hotels.
Should it secure the eighth package of the Jewel of the Creek, however, a significant amount of the contractor’s resources will again be directed towards what is again, arguably Dubai’s most massive project.