VietNamNet Bridge – With some 175 million cubic metres of water stored in an elevated position, Nui Coc Lake’s major dam in the northern province of Thai Nguyen could devastate downstream areas if it broke, experts have said.

Workers check Nui Coc Lake’s major dam in the northern province of Thai Nguyen. Experts believe that the dam could devastate downstream areas if it breaks. — Photo: VNA/VNS

Thai Nguyen City, Song Cong City, Pho Yen Township, Phu Binh District and part of Bac Giang Province would be seriously affected, they said.

The warning was made at a conference on repairing the dam held on Monday.

Last Friday, the provincial People’s Committee announced a state of emergency as the 480 metre-long dam was leaking.

A report from the provincial Department of Agriculture and Rural Development showed that the dam was leaking from its shoulder and from a downstream area.

Large volumes of water were leaking from parts of the dam’s left bank, with downstream drainage ditches suffering damaged and the upper sloping roof sagging.

Viet Nam Hydraulic Engineering Consultants Corporation has said it is necessary to drill to create a water-proof membrane for the entire dam, rebuild the dam’s downstream area, upgrade the downstream drainage system and restore the dam monitoring system.

In the long run, upgrading the whole dam should be considered.

Commenting on the corporation’s plan, PhD Pham Ngoc Quy, former deputy head of the Irrigation University said that water leakage was the main reason dams broke in Viet Nam. The unit must clarify the situation of the dam, including the limit of water leakage.

Quy expressed concerns about the unit’s plan to remove the dam’s downstream roof, which poses the risk of 175 million cubic metres of water flowing downstream.

PhD Nguyen Canh Thai, vice rector of the university called for evaluation of the leaks on the dam body to devise solutions.

He also said that the unit should factor in the possibility of heavy rainfall during the repair work to ensure safety.

Dong Van Tu, director of the Water Resource Directorate’s Department of Project Management and Dam Safety said that it was urgent to dismantle the downstream roof for monitoring and drilling of the leak spots in the centre of the dam before moving to other positions.

The corporation must prepare for possible flooding in the downstream area as high rainfall and flooding are forecast this year, he added.

Doan Van Tuan, vice chairman of the provincial People’s Committee said that a consultant council would be set up to investigate the leaks and conduct the repair work as soon as possible.

Tuan assigned Thai Nguyen Irrigation Exploitation One Member Co Ltd to revise safety measures during the repair work.

Nui Coc Lake is a human-made lake in Thai Nguyen Province. It was built in 1973 and has seven dams. It provides 30 millions cubic metres of water for irrigation per year, 30,000 cubic metres of water for residents per day and between 30,000 and 150,000 cubic metres of water for the Yen Binh Clean Water Plant per day.

VNS