On the afternoon of October 7, prolonged heavy rain caused the water flow to Bac Khe 1 Hydropower Reservoir (Lang Son) to increase dramatically, reaching 1,572 m3/s.
The pressure of the water was too great, causing part of the dam's shoulders to break, creating a sinkhole 4-5 m wide and about 3 m deep.
According to the Department of Industrial Safety and Environment (Ministry of Industry and Trade), the Bac Khe 1 Hydropower Plant is a small hydropower plant with a reservoir capacity of 4.8 million m3, a 107 m long earth dam, a 260 m long concrete spillway, the largest height of 26.5 m, and an installed capacity of 2.4 MW.
The Department said that at the time of the incident, the water flow into the lake suddenly increased to 1,572 m3/s, far exceeding the discharge capacity of the spillway, causing the concrete wall at the water intake to break, causing the central control room to collapse and all equipment to be flooded and severely damaged.
The factory is located isolated, about 400 m from the main traffic road, so initial access to treatment is limited.
Fortunately, nearly 800 affected people were evacuated in time before the water overflowed downstream, with no recorded human casualties.
On November 21, speaking with reporters, Mr. Dinh Ky Giang - Deputy Director of the Department of Industry and Trade of Lang Son province said that immediately after the incident, Bac Khe 1 Hydropower Joint Stock Company (investor) and functional forces have deployed temporary measures to ensure safety and develop a plan to fix the broken location.
Mr. Giang added: "The hydropower dam is starting the safety inspection process according to regulations. After the inspection, the investor will make a repair and repair design. The goal is to complete before the 2026 rainy season.
Accordingly, Bac Khe 1 Hydropower Plant will have to stop operating for at least 6 months to repair.
Immediately after the incident, the People's Committee of Lang Son province requested a review of the entire safety of the lake and dam. It is expected that next week, the Department of Industry and Trade will establish an inspection team at hydropower plants in the area, starting from Bac Khe 1.
In parallel with handling the dam incident, the Provincial People's Committee has approved the Ke project to overcome landslides on the banks of the Bac Khe river, with a total investment of 139 billion VND, invested by the Lang Son Provincial Investment and Construction Project Management Board.
The project to build a 6,616 m long embankment, including the left and right embankment, designed as a sloped roof combined with a vertical wall, aims to overcome landslides, stabilize the flow, protect residents, cultivated land and essential infrastructure along the Bac Khe river.
