The Bhutanese Leading the way.
The concreting of the right bank of the Punatsangchhu Hydropower Project I dam is expected to start in March this year.
Construction of the Punatsangchhu-I Hydroelectric Project started in 2008 and was planned to be completed by 2016, with an estimated cost of over Nu 35 billion. However, geological problems at the dam site have caused long delays, and the project cost has now increased to nearly Nu 100 billion.
All internal components of the dam, including the four desilting chambers, were completed in 2015, and the diversion tunnels have also been fully completed. The remaining work is the construction of the main dam, which has now resumed. Earlier, sliding issues were observed on the right bank. After extensive deliberations between the two governments, it was decided to construct the dam at the same location. Preparatory works have begun, including road works upstream and downstream of the dam.
The dam has a height of 128.5 metres and consists of 13 blocks. Blocks 1 and 2 have already been completed out of the 13 blocks of the bank, while the remaining blocks are yet to be constructed. Issues were identified in blocks 8, 9, 10, 11, 12, and 13 after the slide in the earlier years. Following detailed studies, additional support measures will be provided to these blocks. This includes installing deeper piles of 2-metre diameter to support both the dam structure and the national highway. The sliding portions will also be stabilised using these piles.
Higher-capacity cable anchors, ranging from 150 tonnes to 250 tonnes, will be installed. A cable anchor is a very strong steel cable drilled deep into the rock beneath the dam, then pulled tight and fixed in place. This pulls the dam firmly onto the rock, helping it remain stable, preventing sliding or tipping due to water pressure, and improving the dam’s safety and lifespan. Previously, 100-tonne cable anchors were used, but the capacity has now been increased to 150–200 tonnes. Implementation of these measures will begin shortly, as only a portion of the dam construction remains.
Road works have also started for a 300-metre approach road from the project colony area. Traffic will be temporarily diverted through the colony area. For a permanent solution, a 12.5-kilometre road will be constructed through Gaselo, where a farm road already exists. The national highway will be diverted along this route, and once the diversion is completed, piling work will be carried out on the right bank.
Preparatory works and access routes to different locations are currently underway.
