Mangdechhu project gears for commissioning

…to generate about 3B units of energy with an expected revenue earnings of Nu 7.5B a year

The Mangdechhu Hydroelectric Project (MHPA) is expediting works on all components to meet the commissioning date of June 30, 2018 as scheduled.

Except for the 119m of tunnel excavation works between face 8 and 9 of the 13.5km of head race tunnel (HRT) all faces of the tunnel has been connected.

Works on concrete lining of the ​HRT is being expidited

The HRT has 10 faces starting from the intake desilting chamber, underneath Kuengarabten. Its underground HRT passes through the hill of Samcholing. The powerhouse is located under Yurmong after which the water discharges from the tailrace tunnel.

MHPA’s Managing Director, A K Mishra said that the project has reached a critical stage between face eight and nine of the HRT, where they encountered loose clay. “We are going slow in this area,” he said adding that the slow blasting is followed by strengthening works like mounting frames. Excavation work is scheduled to complete on October 15 this year.

Concrete lining in the HRT is one of the major works overdue. Of the 13.5km, only 3.7km of concrete lining is completed. This is being expedited and it is scheduled to complete by April next year.

As for the dam concreting, a total of 409,471 cubic meters has been achieved as of September 4. Remaining 58,529 cubic meters is due for completion. “By January next year, the dam should be up and gate erection work will start from November,” he said.

By April 2018 all components of the dam is expected to be complete.

Chief engineer of the dam, Sachindra Nath Jha said that all underground components of the dam including desilting chamber and intake tunnel is completed. As of yesterday, workers were found cleaning the desilting chambers, in preparing for commissioning. Gates are also being installed in the chambers. “We are on track. Even the sliding zone on the sides of dam, which buried some workers last year, have been stabilised by a Japanese company.”

In the powerhouse, more than 90 percent of civil works are completed except for the two generating units. Hydro mechanical equipment is being installed in the first unit and while two pressure shafts are already completed, surge shaft is also nearing completion.

The Assistant Executive Engineer of the powerhouse, Wangdi said hydro mechanical and civil works are going simultaneously. “Once the civil works are completed, it is handed over to the mechanical unit for installing of equipment. It is handed back to the civil unit for final touch up,” he said.

However, he said that major works are completed and some, which are due, can be done even after commissioning, as it won’t affect the generation.

AK Mishra said that the project has helped the local economy and the community through 40 pilot projects. The project has deployed 75 local contractors for work worth to Nu 2.4B. Excluding workers from Jai Prakash and Gammon, the 92 percent of the MHPA’s employees are Bhutanese including the engineers. “This project is more or less built by Bhutanese,” A K Mishra said.

He said that all the steel and cement are procured from local manufacturers like Dungsam Cement and Karma steel. “Everything is on track and God is with us,” he said.

Once commissioned, the project will generate about 3B units of energy and the expected revenue earning is Nu 7.5B a year. After the loan repayment, the country will get to keep around Nu 3.5B a year in its coffer. This is considering the export tariff at Nu 2.50 a unit.

While the Mangde valley appear calm and lush, underneath the hills, at least a thousand workers are undertaking a massive work to commission the 720MW project on schedule. The white board in the project head office keeps the count down to remind employees of the progress. As of September 4, it reads 298 days to commission.

Tshering Dorji | Trongsa

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