The Grassroots Acceptance Council inspected and approved the Headrace Tunnel for the Da Nhim Hydropower Plant Expansion project on July 20, 2021. The Acceptance Council agreed to put in into operation on July 21, 2021, six days ahead of schedule, after inspecting the entire length of 4,908.57m from the Intake to the Valve House.
Regarding members of the Grassroots Acceptance Council, there were leaders of Da Nhim Hydropower Plant Expansion Project Management Board (representative of Da Nhim – Ham Thuan – Da Mi Hydropower Joint Stock Company as the Investor), Supervision Consultant (Nippon Koei – PECC3 – Nippon Koei Vietnam), Design Consultant (Power Engineering Construction Joint Stock Company 2), Construction Contractor (Construction Joint Stock Company 47) and Hydro-mechanical Contractor (NARIME – COMA Consortium).
Headrace Tunnel under Da Nhim Hydropower Plant Expansion Project with a total length of 4,908.57m is constructed by TBM (Tunnel Boring Machine) and partly by Drilling and Blasting method. Tunneling work with TBM started on April 1, 2017 with a diameter of 3.9m. On March 23, 2019, when 3,739.51m had been drilled, the tunnel slippage occurred when the TBM passed through a weak geological area. Although the Owner, Consultant and Contractor have made efforts to reinforce and fix the tunnel but the TBM equipment cannot continue to dig the remaining tunnel.
Following approval from the Ministry of Industry and Trade to change the TBM construction plan to drilling and blasting for the remaining 929.05m tunnel, the Construction Contractor resumed work on February 6, 2020, and completed the tunnel on December 14, 2020. After about 6 months of focusing on covering and reinforcing the tunnel at sections with weak geology and overall hygiene, the entire tunnel was ready for acceptance and use on July 20, 2021.
Mr. Luu The Bieu – Deputy Director of the Project Management Board – did not hide his emotion when speaking at the acceptance meeting to put the tunnel into use on the same day: “After a difficult time of construction, the Headrace tunnel is ready for water filling. The Da Nhim expansion project is now officially completed. What makes me proud of is the tunnel quality and the construction safety for laborers and equipment”.
To ensure the progress of putting unit H5 of 80 MW under the Da Nhim expansion project into operation in the third quarter of 2021, Da Nhim – Ham Thuan – Da Mi Hydropower Joint Stock Company (DHD) launched an emulation on 16th June 2020. The emulation aims at catching the schedule of filling the tunnel on July 26, 2021 and completing the 72-hour challenge of unit H5 with a capacity of 80MW on August 8, 2021. The completion of the Headrace Tunnel of Da Nhim Hydropower Plant Expansion Project was 6 days ahead of schedule.
The Headrace Tunnel Item under Da Nhim Hydropower Plant Expansion Project is completed ahead of schedule and is considered a crucial basis to put Unit H5 into operation for resource efficiency. Up to now, the inspection of unit H5 after 2.5 years of operation with a capacity of 45MW is being carried out urgently, completing the final items to operate with a capacity of 80MW.
Unit H5 with a capacity of 80MW will increase the total capacity of Da Nhim hydropower plant to 240MW, contributing to additional power sources, especially at off-peak hours for the national power grid. As a multi-purpose hydropower plant, Da Nhim hydroelectricity annually provides more than 1.1 billion kWh for socio-economic development; At the same time, it is an abundant water source for agricultural production in the delta of Ninh Thuan province.