Repaired dam ‘safe from earthquakes'
QUANG NAM (VNS)— Work to repair leaks on the Song Tranh Dam had been completed and the Song Tranh Hydropower Plant in the central province of Quang Nam was safe, even after a 5.5 Richter earthquake, the deputy chairman of the State Council for Assessment and Acceptance of Construction Works, Nguyen Van Lien, said at a press conference yesterday.
Leaks on the dam through 30 compression joints had been sealed successfully, reducing 90 per cent of water running through them.
"A series of inspections have been conducted at the plant since the leaks were found. The 10 largest leaks, which were spilling 26.2 litre of water per second, have been stemmed to 0.02 litres per second," Lien told the press conference.
"We invited experts and scientists from the Geophysics Institute, the Power Engineering Consulting Joint Stock Company No 1, and the independent consultant Swiss' AF-Colenco to conduct inspections of the hydropower plant," he said.
Lien, however, said although the plant had been declared safe, it would not allow the reservoir to fill during the rainy season following instructions from Deputy Prime Minister Hoang Trung Hai.
"We'll make further inspections and assessments of the plant's stability from the impacts of flood and earthquakes."
Le Huy Minh, deputy director of the Geophysics Institute under the Viet Nam Academy of Science and Technology, said that the plant was safe, despite multiple quakes and tremors.
"We can confirm that over 20 earthquakes and tremors occurred in Bac Tra My district, but none exceeded 5.5 on the Richter scale," Minh said.
"We surveyed the site and mapped out different seismic regions. We recorded that the plant sits on a 20-km-long and 10-km-wide seismic area, with maximum potential of a 4.4 quake, well within the plant's design," he added.
However, deputy general director of Electricity of Viet Nam (EVN) Tran Van Duoc admitted that compression joints on the dam had not been fitted properly, resulting in the leaks.
"We have stopped water leaking through the compression joints, but we need time to test if it is safe to fill the reservoir again," Duoc said.
The general director of the Power Engineering Consulting Company No 1, Nguyen Tai Son said: "We lacked experience in environmental assessment when construction of the plant started in 2006. We'll set a seismic observation system for a prolonged period in the region to ease the fears of local people."
Pham Huu Sy, an expert from the State Council for Assessment and Acceptance of Construction Works, said there were fault zones in Bac Tra My, but none of them crossed the dam. — VNS