After 13 years of construction, the mammoth Three Gorges Dam project enters a landmark stage with Saturday's completion of dam structure.

The 1,000-cubic-metre final part of the concrete placement, which began at 4 am on Friday, is set to finish at around 2 pm on Saturday, officials with the Yichang Qingyun United Hydropower Company told the Xinhua News Agency on Friday.

"This is the grandest project the Chinese people have undertaken in thousands of years," said Li Yong'an, general manager of the China Yangtze River Three Gorges Project Development Corporation.

Li said that the project is running ahead of schedule and will solve "one of the Chinese people's worst afflictions" the flooding that has ravaged the Yangtze basin for centuries.

The 185-metre-high, 2,309-metre-long dam, which will replace Brazil's Itaipu Dam as the world's largest hydro-electric and flood-control installation, is often compared to the Great Wall in scale with 28 million cubic metres of concrete poured.

More than 1.13 million people have been relocated to make way for the project, and more than 100 workers reportedly lost their lives in various accidents during construction.

The dam is solid enough to withstand natural disasters and terrorist attacks, said Cao Guangjing, deputy general manager of the corporation.

It has also been designed to withstand an earthquake measuring 7.0 on the Richter scale.

China will spend 10 million yuan (US$1.25 million) annually to prevent upstream floating rubbish from piling up at the dam, thereby ensuring that vessels travelling past the dam operate safely.

According to project development corporation officials, the volume of floating rubbish into the Three Gorges Reservoir amounts to 100,000-200,000 cubic metres each year, most of which accumulates in flood seasons.

The government has set aside US$5 billion to build sewage treatment plants around Chongqing and other upstream cities to prevent the river from turning into a cesspool, Cao said.

"Reservoirs worldwide are being more or less beset by rubbish, and the Three Gorges Reservoir is no exception," said Hu Xing'e, a corporate official in charge of reservoir business.

The corporation has spent more than 20 million yuan (US$2.5 million) on building a rubbish-clearing vessel, so far the largest of its kind in China. Floating rubbish that is collected will be sorted out and then be buried or burnt.

Apart from generating clean energy, the landscape-altering mega-project, with a designed water storage capacity of 39.3 billion cubic metres, will also harness flooding and benefit shipping.

Cao Guangjing said his company has taken comprehensive measures to deal with environmental problems.

There have been concerns that the project would affect lives, water quality, cause silt accumulation and maybe even modify local climate slightly in the dam's vicinity.

"The negative effects on the environment caused by industrial sewage and dust produced in the project's construction process are under control," Cao said.

The government has decided to shut down 1,000 polluting enterprises in the upper reaches of the project.

Launched in 1993, the Three Gorges Project, with an estimated investment of 203.9 billion yuan (US$25.2 billion), will have 26 generators with a combined generating capacity of 18.2 million kilowatts.

The generators will churn out 84.7 billion kilowatt-hours a year when the final touches are completed in 2008, officials said.

China Daily - Xinhua