The Song Tranh 2 hydro-power plant has three tunnels that run inside the dam at the heights of 152m, 124m and 95m. Tunnels are over 3m wide, 2.5m high on average, totaling nearly 2km long. There are two drains along the path inside tunnels to collect water to a pipe.
These tunnels are connected with each other by pipes. The tunnels are also the paths for technicians to check and maintain safety for the dam.
On the afternoon of March 28, water spouted everywhere inside these tunnels, from the ceilings, from the walls and from the grounds. Water rushed to two newly-installed pipes to the tunnel doors to the dam downstream.
Inside the tunnels, workers wore raincoats, carried sand bags to prevent water. Guards did not allow strangers to get into the tunnels.
At a press conference in Hanoi on March 28, Deputy Minister of Industry and Trade, Hoang Quoc Vuong, said that Vietnam has built 14 hydro-power plants that used the roller-compacted concrete technology, like the Song Tranh 2 dam. Previously, leaks also appeared at the Pleikrong hydro-power plant in Kon Tum province, with leaking water running at the speed of 25l per second. After being fixed, the current speed was only 3l/second, meeting the designed standards and it has been operating safely since then.
The Pleikrong and Song Tranh 2 plants have the same design consulting firm – the Electric Construction Consulting JS Company.
However, after researching photos of leaks inside the tunnels of Song Tranh 2 plant, some experts said that the dam’s lifespan will be affected and they asked to inspect the leaks.
Deputy Director of the Department of Science and Technology of Quang Ngai province, Mr. Pham Ngoc Sinh, said that the volume of water running through leaks inside the tunnels is remarkable and it may highly affect the lifespan of the dam.
Dr. Pham Hong Giang, Chair of the Vietnam Association for Big Dams, said that if water spouted inside the tunnels, construction errors are obvious.
Dr. Nguyen The Hung, Vice Chair of the Vietnam Mechanics Association, an expert of irrigation technology of the Danang Polytechnic College, said that it is needed to find out that water currents inside the tunnel come from contraction and expansion joints or from leaks.
Experts said that it is needed to set up a group of leading experts of various fields to check the dam again. “The leakage can be fixed completely if the errors are defined correctly,” Mr. Hung said.
Water spouts inside dam tunnels: