Major project on the nile

IMHOTEP, MASTER BUILDER TO THE PHARAOHS, HAD THE IDEA FOR THE FIRST PYRAMID. TODAY BILFINGER BERGER IS ERECTING A STRUCTURE ON THE NILE OF SIMILAR DIMENSIONS: 400,000 CUBIC METERS OF CONCRETE WERE USED TO BUILD THE NAGA HAMMADI DAM WHICH WILL PROVIDE WATER AND ELECTRICITY.

The experiment ended in disaster. Under the weight of the mud bricks, the eight-meter high wall collapsed. The new material— a combination of mud, straw and strips of fabric—was obviously not the right solution. Master builder Imhotep was disappointed. This would not suffice for a 60-meter high structure designed to last for eternity. Imhotep developed a new plan, envisaging a structure built of hewn stone blocks.This marked the birth of building in stone, a method first used 4,600 years ago for the pyramid of Sakkara. Imhotep was a man of exceptional imagination. He improved the system of irrigation along the Nile to such an extent that the farmers could water their fields even when the river was low. Imhotep’s achievements brought him immortal fame, and the ancient Egyptians came to worship him as a god.

Much as today’s visitors gaze upon the pyramids with amazement, Imhotep would himself catch his breath at the sight of what his successors are achieving in Naga Hammadi: together with French and Egyptian partners, Bilfinger Berger is constructing an imposing retaining weir, 340 meters long at a cost of € 300 million. It comprises a weir with seven gates, each weighing 160 tons, two locks for shipping and a power station with a capacity of 64 megawatts— enough to supply around 200,000 households with electricity. The locks are 17 meters wide and over 160 meters in length, sufficient even for the largest tourist vessels that are expected to shuttle between the Temple of Abydos and Luxor. While work continues, the Nile has had to be diverted into an artificial bed. Six and a half million cubic meters of soil were excavated just for this channel. By comparison, it took five million cubic meters of stone to build the pyramids of Cheops. The 400,000 cubic meters of concrete poured into the weir are enough to fill the Cologne cathedral.

Simply getting the construction materials to this remote site some 700 kilometers south of Cairo at the right time represents a notable logistics achievement. The cement comes from Suez, the sand from Luxor and the steel from Alexandria. Great balks of American pine are just being fitted to the lock entrances under the supervision of a petite young woman. Civil engineer Nathalie Néron was possibly the biggest sensation of all for the Egyptian workmen. A woman in charge? “It took a while for them to get used to me,” says the 25-yearold with an air of confidence, “but once they did, my crew worked all the better. I only had to threaten to do a job myself, and three of them rushed to do it at once to spare themselves the dishonor.” Néron came to the desert straight from the École Supérieure des Travaux Publics in Paris, and she is proud of her job: “Even a few years ago, I could never have dreamt of helping to build such an important structure.”

The project is vital for the future of Egypt. The country’s problems remain unchanged in principle since Imhotep’s time: not even a blade of grass will grow without irrigation. The fertile Nile valley and delta make up just four percent of the land area, but they are home to 97 percent of Egypt’s almost 80 million inhabitants. The population is growing at the rate of a million a year. The existing barrages in place between the Aswan Dam and Cairo would not be adequate to meet the demand for water in the next 20 years.

So the engineers at the Ministry of Water Resources did their sums: if the old weir at Naga Hammadi, built by the British in 1930, could be raised by just one meter, irrigation in the hinterland would be vastly improved, creating 3,150 square kilometers of new arable land. After three quarters of a century, however, the weir composed of a hundred brick arches was showing its age. Therefore, the Egyptian government decided to build a new barrage weir three and a half kilometers down river from the old structure.

FUNDING FROM EUROPE
When the first engineers arrived to begin a survey of Hammadi a short time later, the local residents gave them an angry reception. It took police protection to persuade the surveyors to venture into an area whose inhabitants have long enjoyed a reputation as stubborn and vengeful. Why should they give up their fertile sugar cane plantations and in some cases even leave their houses, just to make way for a weir? Only when word spread that the Egyptian government would pay generous compensation for the loss of their land did the farmers begin to warm to the plans. In the long term, the retaining weir will help to safeguard the future existence of the population who derive their income mainly from agriculture. In addition, the hydroelectric plant will be a source of environmentally friendly power. An accompanying environmental program, including the renaturalization of areas spoiled during construction, will ensure that this major project sponsored by Germany’s Reconstruction and Development Bank (KfW) and the European Investment Bank (EIB) is an all-round development policy success.

CONCRETING AT 50 DEGREES CELSIUS
Before work could begin on the weir, it was first necessary to set about diverting the course of the Nile, which flows through Hammadi at an average rate of 45 billion cubic meters per year. The plans called for a 1.3-kilometer long diversionary canal on the western side of the river, where the loamy subsoil promised more stability than the sandy soil to the east. In June 2002 the excavators moved in, and day and night 350 trucks hauled the excavated material away to be stockpiled. The 15- meter deep canal had to withstand erosion, even in flood conditions when the Nile carries up to a thousand cubic meters of water per second. Egyptian workers stitched a synthetic fiber fleece supplied from Germany into long strips and spread it out in the bed of the canal. The Nile was then let into the canal a little at a time to ensure that the fleece did not tear. Finally the old course of the river was blocked with a dam that forced the Nile to abandon its former bed and flow around the construction site.

But that was where the real challenge began. In the past ten years it has rained once in Hammadi. For all of a quarter of an hour. The children ran out their houses and screamed with delight at such a wonder. Then the sun came out again. Outside temperatures in the summer months can reach over 50 degrees Celsius. Laying even a bucketful of cement means working fast. Concrete dries in no time, cracks, crumbles and fails. Nevertheless, the concrete for the two-meter thick base of the weir had to be perfect. So icemakers were installed next to the mixing plant and chunks of ice were added to the concrete, up to 120 tons every day. Concrete specialists constantly monitored the correct temperature, consistency and composition of their recipes.The base slab, power station building and lock walls all needed special mixtures of cement, water and aggregate to suit their particular function. This technical expertise was one of Bilfinger Berger’s particular contributions to the joint venture, for which the company sent its experts in concrete technology.

Bilfinger Berger has now almost completed its work.The lock gates and weirs are being erected, the four turbines installed in the power station and the site is slowly being flooded. The inauguration is scheduled for May 2008. Ministers will be on hand, the international sponsors will send representatives to Hammadi, and many of the 3,000 men and women who worked on the project will return for the celebrations. Someone from Bilfinger Berger has cast the company logo in concrete and attached it to one of the retaining walls by the inlet to the power station—a few meters below the waterline, naturally. After all, who would want to dispute Imhotep’s place in the land of his fathers?

(Text: Philipp Mausshardt, Photos: Barbara Breyer)