Overview of Bac Ai Pumped-Storage Hydropower Plant Project construction site. Photo: Ngoc Linh

Bac Ai Pumped-Storage Hydropower Plant: Overcoming geological challenges

At the Bac Ai Pumped-Storage Hydropower Plant Project in Bac Ai Tay Commune, Khanh Hoa Province, construction initially proceeded under favorable geological conditions, with tunnel excavation progressing at approximately 40% above the average rate. However, from mid-March 2026, the contractor encountered Class IV fractured geological conditions at the VH3A construction and operation tunnel, a key component serving the construction and operation of the water conveyance tunnel and the upper reservoir.

The weak geological conditions required the contractor to excavate the tunnel meter by meter while carrying out extensive reinforcement works, including the installation of steel support frames and shotcrete to stabilize the tunnel crown and prevent subsidence. As a result, the excavation rate fell to approximately 1 meter per day, compared with around 4.5–5 meters per day previously.

Inside VH3A tunnel, drilling equipment is being used to install steel reinforcement frames before shotcrete is applied to reinforce tunnel crown. Photo: EVNPMB3

Thanks to coordinated solutions, progress on the VH3A tunnel has been maintained during the challenging months. Key works, including the construction and operation tunnel, the first ventilation section, and the construction tunnel, have already met their full-year 2026 targets.

Tri An Hydropower Expansion Project: Entering critical stage

Unlike the Bac Ai Pumped-Storage Hydropower Plant, which involves underground tunnel excavation through mountainous terrain, the Tri An Hydropower Expansion Project in Tri An Ward, Dong Nai City, is being constructed as an open-air power plant. As a result, construction progress depends heavily on weather conditions and site clearance.

oncrete works for powerhouse’s bottom slab reached 125% of monthly target in July. Photo taken on August 12, 2026.

By August 2026, the project’s entire site had been handed over, providing an important foundation for accelerating construction across the project site, including the Hieu Liem Bridge—strategic infrastructure serving local travel needs as well as the transportation of equipment and materials for the project.

With these results, the project has officially entered the stage of simultaneous construction of its main components and equipment manufacturing.

At Hieu Liem Bridge area, contractor is focusing on earth filling and roadbed compaction for approach road connecting DT768 provincial road to center of Dong Nai City. Photo taken on August 18, 2026.

Regarding Hieu Liem Bridge, although progress has been significantly affected by weather conditions, the contractor continues to accelerate multiple finishing activities simultaneously. The approach road on the Tri An Hydropower Plant side has been completed. On the other side, toward Provincial Road DT768 and the center of Dong Nai City, construction crews are accelerating ground leveling, earth filling, and roadbed compaction for the bridge approach road, with the aim of completing the work before the end of August and opening the bridge to traffic in September 2026.

Quang Trach 1 Thermal Power Plant: On track for completion

While the two hydropower projects are focused on overcoming challenging construction conditions, the Quang Trach 1 Thermal Power Plant Project in Quang Tri Province, represented by Power Project Management Board No. 2 as the project owner’s representative, is concentrating on the final stages. To date, overall project progress has surpassed 99%. Unit 2 has completed its first boiler firing and is continuing with commissioning activities, while Unit 1 has successfully completed commissioning at 100% of its rated load, corresponding to an actual output of 701.5MW. This is an important milestone in the commissioning process toward commercial operation of the unit.

In addition, operational facilities such as the coal transportation and coal handling systems have been installed and commissioned. Technology transfer training and on-the-job training (OJT) for operating personnel are also being conducted simultaneously.

Coal port area at Quang Trach Power Center. Photo: Ngoc Tuan

Alongside efforts to accelerate progress, health, safety, and environmental protection measures continue to be strictly maintained. To date, the project has achieved more than 25 million safe working hours, with no serious occupational accidents or environmental incidents recorded.

Faced with different project requirements and challenges, the project management boards and contractor consortia have proactively adjusted construction arrangements, strengthened continuous coordination among the project owners, consultants, and contractors, and implemented comprehensive measures to ensure safety and prevent and mitigate natural disasters. These efforts provide a solid foundation for the projects to remain on track with their planned milestones, contributing to the accelerated addition of new power generation capacity to the national power system in accordance with EVN’s development plan.

Translator: Phạm Gia Đại