River deltas are difficult places
for map makers. The river builds them up, the sea wears them down; their outlines are always changing. The changes in China’s Pearl River delta,
however, are more dramatic than these natural fluctuations. An island six kilometers long and with a total area of 1248 hectares is being created there. And the civil engineers are as
interested in performance as in
speed and size. This is a bit of the delta that they want to endure.

The new island of Chek Lap Kok, the site of Hong Kong’s new airport, is 83% complete. The giant dumper trucks rumbling across it will have finished their job by the middle of this year and the airport itself will be built at a similarly breakneck pace.

As Chek Lap Kok rises, however, another new Asian island is sinking back into the sea. This is a 520-hectare island built in Osaka Bay, Japan, that serves as the platform for the new Kansai airport. Chek Lap Kok was built in a different way, and thus hopes to avoid the same sinking fate.

The usual way to reclaim land is to pile sand rock on to the seabed. When the seabed oozes with mud, this is rather like placing a textbook on a wet sponge: the weight squeezes the water out, causing both water and sponge to settle lower. The settlement is rarely even: different parts sink at different rates. So buildings, pipes, roads and so on tend to buckle and crack. You can engineer around these problems or you can engineer them out. Kansai took the first approach; Chek Lap Kok is taking the second. The differences are both political and geological. Kansai was supposed to be built just
one kilometer offshore, where the seabed is quite solid. Fishermen protested, and the the site was shifted a further five kilometers. That put it in deeper water (around 20 meters) and above a seabed that consisted of 20 meters of soft alluvial silt and mud deposits. Worse, below it was a not-very firm glacial deposit hundreds of
meters thick.

The Kansai builders recognized that settlement was inevitable. The sand was driven into the seabed to strengthen it before the landfill was piled on top, in an attempt to slow the process; but this has not been as effective as had been hoped. To cope with the settlement, Kansai’s giant terminal is supported on 900 pillars. Each of them can be individually jacked up, allowing wedges to be added underneath. That is meant to keep the building level. But it could be a tricky task.

Conditions are different at Chek Lap Kok. There was some land there to begin with, the original little island of
Chek Lap Kok and a smaller outcrop called Lam Chau. Between them, these two outcrops of hard, weathered granite make up a quarter of the new island’s surface area. Unfortunately, between the islands, there was a layer of soft mud, 27 meters thick in places.

According to Frans Uiterwijk, a Dutchman who is the project’s reclamation director, it would have been possible to leave this mud
below the reclaimed land, and to deal with the resulting settlement by the Kansai method. But the consortium that won the contract for the
island opted for a more aggressive approach. It assembled the world’s largest fleet of dredgers, which sucked up 150m cubic meters of clay and mud and dumped it in deeper waters. At the same time, sand was dredged from the waters and piled on top of the layer of stiff clay that the massive dredging had laid bare.

Nor was the sand the only thing used. The original granite island which had hills up to 120 metres high was drilled and blasted into boulders no bigger
than two metres in diameter.
This provided 70m cubic metres of granite to add to the island’s foundations. Because the heap of boulders does not fill the space perfectly, this represents the equivalent of 105m cubic meters of landfill. Most of the rock will become
the foundations for the airport’s runways and its taxiways.

The sand dredged from the waters will also be used to provide a two-metre capping layer over the granite
platform. This makes it easier for utilities to dig trenches – granite is unyielding stuff. Most of the terminal buildings will be placed above the site of the existing island. Only a limited
amount of pile-driving is needed to support building foundations above softer areas.

The completed island will be six to seven meters above sea level. In all, 350m cubic meters of material will have been moved. And much of it, like the overloads, has to be moved several times before reaching its final resting place. For example, there has to be a motorway capable of carrying 150-tonne dump-trucks; and there has to be a raised area for the 15,000 construction workers. These are temporary; they will be removed when the airport is I finished.

The airport, though, is here to stay. To protect it, the new coastline is being bolstered with a formidable twelve kilometres of sea defences. The brunt of a typhoon will be deflected by the neighboring island of Lantau; the sea walls should guard against the rest. Gentler but more persistent bad weather – the downpours of the summer monsoon – is also being taken into account. A mat-like material called geotextile is being laid across the island to separate the rock and sand layers. That will stop sand particles from being washed into the rock voids, and so causing further settlement. This island is being built never to be sunk.

Questions 1–5 AIRPORTS ON WATER IELTS READING

Classify the following statements as applying to
A Chek Lap Kok airport only
B Kansai airport only
C Both airports

Write the appropriate letters A–C in boxes 1–5 on your answer sheet.

1. having an area of over 1000 hectares
2. built-in a river delta
3. built-in the open sea
4. built by reclaiming land
5. built using conventional methods of reclamation

Questions 6–9–AIRPORTS ON WATER IELTS READING.

Complete the labels on Diagram B below.
Choose your answers from the box below the diagram and write them in boxes 6–9 on your
answer sheet.

NB There are more words/phrases than spaces, so you will not use them all

DIAGRAM A
Cross-section of the original area around Chek Lap Kok before work began

DIAGRAM B
Cross-section of the same area at the time the article was written.

Questions 10–13 – AIRPORTS ON WATER IELTS READING.

Choose your answers from the box below the summary and write them in boxes 10–13 on your
answer sheet.
NB There are more words than spaces, so you will not use them all.

The island will be partially protected from storms by … (10) … and
also by … (11) … . Further settlement caused by … (12) … will be
prevented by the use of … (13) … .

AIRPORT ON WATER IELTS READING ANSWER