On March 21, an interdisciplinary inspection team from Quang Nam province and the State Appraisal Department of Construction Quality (Ministry of Construction) inspected the water leakage phenomenon at the main dam of Song Tranh 2 Hydropower Plant, Tra Tan Commune, Bac Tra My District, Quang Nam Province.
At the main dam, the inspection team recorded 7 water streaks flowing from the dam body, including two streaks on both sides of the spillway with the largest flow. After inspecting the scene, members of the interdisciplinary inspection team requested the Song Tranh 2 Hydropower Project Management Board to recognize the true nature in order to take measures to handle it. Currently, there are many water streaks that appear out of order in the cracks, in a zigzag shape that need to be carefully examined. Opinions also suggested considering the relationship between water leakage in the dam body and the recent earthquake that occurred in Bac Tra My district.
On the same afternoon, at the People's Committee of Bac Tra My district, under the chairmanship of comrade Nguyen Duc Hai, Secretary of Quang Nam Provincial Party Committee.Male, related units have reported on the phenomenon of water leakage at Song Tranh 2 Hydropower Plant. Mr. Dang Phong, Chairman of Bac Tra My District People's Committee, expressed concern about the possibility that Song Tranh 2 Hydropower Plant was affected by the recent earthquake, and recommended that the authorities study and give specific causes to have a conclusion and promptly notify the people.
The contractor of Song Tranh 2 Hydropower Plant needs to immediately handle the error causing the water leak. Photo: Internet
On behalf of the State Appraisal Council, Dr. Bui Trung Dung, Deputy Director of the State Appraisal Department of Construction Quality (Ministry of Construction) assessed: Through inspection, it was found that there were no cracks in the dam body and shell, the hydropower plant is operating at a safe level according to the design. According to Dr. Dung, the cause of the water leakage is the lack of a waterproof membrane on the dam shell, the lack of drainage pipes in the basement, so water seeps into the expansion joints and escapes. In addition, the water level seeping through the dam body is about 30 liters/second, which is large but does not affect the safety of the dam, but causes disgust and resentment among the people, so it is necessary to reduce the amount of seeping water. The Appraisal Council requires the contractor to immediately take measures to eliminate water in the tunnel trench; at the same time, waterproof the dam shell.
On the same day, Vietnam Electricity Group (EVN) concluded the water seepage problem at Song Tranh 2 Hydropower Plant. From March 18-20, EVN's working group worked with the units on the project. Based on the results of the work at the site, EVN gave an initial assessment of the water seepage problem downstream of Song Tranh 2 Hydropower Plant. Song Tranh 2 Hydropower Plant is a roller compacted concrete (RCC) gravity dam with a height of 96 m and a length of 640 m, divided into blocks, the blocks are separated by thermal gaps (a total of 30 thermal gaps, 30m apart) running from upstream to downstream. The purpose of arranging these thermal slots is to eliminate thermal stress in the concrete during construction and operation of the project... At the site, the Working Group directly inspected the entire dam body and water intake corridors and made the following assessment: No cracks were detected on the dam body; the phenomenon of water flowing from the dam body downstream is water seepage at 4 thermal slots K18, K21, K24, K28 and both sides of the spillway field (the area between the dam and the spillway).
The reason is that the seepage water is not collected completely in the water collection corridors in the dam body and through the pipes to the downstream. The total seepage water of the entire project is regularly monitored and observed and at present is measured at about 30 liters/second, which is assessed by consultants as not affecting the safety and stability of the dam.
The working group directed the completion of the seepage collection and drainage system in two steps. First, focus on checking the entire seepage collection and drainage system according to the approved design, immediately clearing all water collection pipes in the dam body that were clogged during the construction process and the recent operation period. If any pipes cannot be cleared, additional drilling will be done immediately. At the same time, complete the drainage system in the dam body corridor to increase the seepage drainage capacity and complete the seepage collection system outside the two dam shoulders. After implementing the above steps, if the seepage to the downstream does not decrease, EVN will consider additional waterproofing treatment options to ensure the best waterproofing conditions for the project. At the same time, EVN directed the Project Management Board to coordinate with the design consultant and related units to immediately analyze the monitoring data to assess the safety of the dam.
According to VNA
