As the sea is welcomed back to the area, an atmosphere of calm and majesty gives a glimpse of a building site’s transformation into a future crown jewel of Saadiyat island.
Serenity is not a word normally associated with building sites but after three years of near-continuous construction, a curious sense of calm has descended over the precincts of the Louvre Abu Dhabi.
During the recent stages of the museum’s creation, the presence of hundreds of temporary towers, cranes and thousands of workers lent the site a shadowy, hivelike atmosphere.
With the external spaces approaching their final state, focus has shifted to finishing the building’s interior.
The source of the site’s newfound composure, however, lies not in any absence of machinery outside but in the addition of an element – the sea.
It laps at the underside of the broad bridges that will carry visitors from the Louvre Abu Dhabi’s beach to the pools, plazas and galleries that form the heart of the new island museum.
After seven years of continuous effort to keep the museum’s construction site dry – with dampness being a huge enemy of art storage, the neon waters of the Arabian Gulf have slowly and methodically been welcomed back, transforming its precincts from a shadowy peninsula of rusting metal and bare concrete into an archipelago filled with the delicate movement of water and reflected light.
“This project combines one of the most aggressive external environments – seawater – and one of the most stringent requirements for dryness,” says Brian Cole, a director with BuroHappold Engineering, the consultants responsible for making it possible for the sea to enter the museum site while being protected from it at the same time.
“Art storage is probably one of the most highly controlled internal environments, so we needed the highest degree of watertightness.”
The process of “flooding” the site was completed in a few weeks, but the sequence of works that were required to get to this stage began in 2009 with the reconstruction of the entire north-west corner of Saadiyat Island.
“This enabled the construction of a platform that the museum could be built on, as well as excavation down to the required level,” says Mr Cole.
Flanked by open water on three sides, the Louvre Abu Dhabi’s basement is 10 metres below sea level.
“We’ve used every measure we can,” Mr Cole says. “We have a double-layer system of waterproofing and we’ve created a watertight concrete box, not just because we’re going to have expensive artworks inside, but because the client wanted a 100-year design life.
“Repairing this building will be very difficult because it stands in the sea. Other buildings that stand in the sea, such as the Burj Al Arab, do so on a platform, but here we have the sea coming up to the sides of our building, which is quite unusual.”
A layered system of 278 marine piles, concrete breakwaters, tidal pools and a specially designed “wearing wall” also protect the museum from the effects of maritime traffic, the vicissitudes of the Gulf’s weather and any potential security threats that might come from the sea.
Four metres high and weighing about 10 tonnes each, the precast units of the museum’s wearing wall are made of special, ultra-high-performance concrete that not only allows them to protect the museum from the effects of waves but also enables them to bend outward – a key consideration during a receding tide when rapidly falling water pressure can create a suction-like effect on the museum’s cladding.
At the beginning of the construction process, the most immediate challenge facing the Louvre Abu Dhabi’s engineers and designers was the fact that the museum had to be built in what was effectively a giant dry dock.
The construction of this enormous structure began with the installation of a retaining wall, made by dropping boulders off barges into the sea. This created a new, temporary coastline, which was then backfilled using sand pumped from the sea bed.
A hydraulic cut-off wall was made from interlocking concrete piles that descended to the island’s bedrock, and it was only once this barrier was in place that the task of draining Saadiyat’s sodden sands could begin.
Despite the retaining wall and cut-off wall, the site was not watertight. So 28 wells were dug, with pumps placed at the bottom of each. Eighteen of those pumps ran continuously in a Sisyphean process that involved removing an estimated 250 cubic metres of water an hour, every hour, for six years.
With the backfill drained, Bauer International, the German contractor charged with carrying out the project’s early enabling works, had to excavate 503,000 cubic metres of sand before they could build the 4,500 piles forming the museum’s foundations, a task that was completed in 2010.
“Except for the four points where the dome is supported, the museum is only a two or three-storey building, which means that it’s relatively light,” Mr Cole explains.
“When we were still dewatering the site, the piles were taking vertical loads downwards because there was no hydraulic uplift, but when we stopped dewatering, the predominant forces on the building changed.”
For this reason the majority of piles, some of which are 25 metres long, were designed to support the museum during construction only. Now that the site is flooded, they ensure the structure is anchored securely.
“In our case, water pressure will form on the underside of the raft [foundation] to such an extent that it will exceed the weight of the building, creating a net uplift,” Mr Cole says.
“The building weighs less than the water pressure underneath it, which makes it more like a ship that’s permanently tethered.”
Before the final flooding of the site could take place, the team overseeing the works had to make sure all the jobs requiring land-based access on the seaward side of the building were complete.
“We had to remove the tower cranes and their bases, and there were hundreds of towers and platforms on site,” Mr Cole says.
Once all the necessary checks had been made, the process of allowing water back in began with 15 of the 18 pumps being turned off to allow a steady increase in the water level, at a controlled rate of 15 centimetres a day.
“Once the water started to rise, we had teams in the basement constantly checking for leaks,” says Stephen Venney, one of the senior project managers with Abu Dhabi’s Tourism Development and Investment Company, which is charged with delivering the project.
“It was only once we determined that there were no issues that we turned off the remaining pumps,” he says.
“This is a major milestone. The sea is now part of the Louvre and everybody, visually, can translate the design intent.
“We had a date set for completion of the flooding, we had to meet it – but to achieve that we’ve had to work day and night.”
nleech@thenational.ae
