DOLAKAH, Feb 19
Construction of dam of the 456 MW Upper Tamakoshi Hydropower Project will be completed within six months. Work on the left side of the dam, under headworks, has been completed and work on the right side is currently being done by diverting the course of river. The project, however, will only be completed in July, 2016 even though the dam will be completed in six months.
Work of foundation has already been completed two months after changing course of the river. Assistant Manager of the project Bimal Gurung says one-third of the dam is completed when foundation is finished. A 30-meter dam on the left side, intake, and 200-meter settling basin have been completed in the headworks. “It will be completed before the monsoon as only construction on the right side remains now. Work is being done on war footing to complete it in scheduled time. We have been working for 22 hours on a stretch to concretize it,” he adds.
Work on 30 meters of dam out of the 60-meter long and 22-meter high dam in Lamabagar is currently being done by changing course of the river. A total of 177,000 cubic meter had to be concretized in headworks and 155,000 cubic meter of that has been completed. Headworks alone will require 50,000 tons of cement and 12,000 tons rods. More than half of the workers in headworks have been laid off with civil construction gradually completing. While over 1,000 workers used to work at headworks a year ago, there are less than 500 now.
Work on dam, intake, gate on desander, and design, installation, test and commissioning of stoplog under hydromechanical works are being done now with civil works nearing completion. Sino Hydro Corporation of China is doing civil works while Indian company Texmaco Rail and Engineering Limited is doing hydromechanical works.
Consultant fails in dam
Study by consultant Norconslut AS of Norway on construction of the dam on the right side has failed with a weak cliff with soil and sand in the middle being found during construction even though the study had said there were hard rocks in there.
The cliff has now become another problem. The project deeming that working as per the previous design will lead to risk of seepage of water through the hole in the cliff and can weaken the dam is preparing to address the issue now investing more time and capital. Gurung says additional study will be conducted even by hiring additional experts from abroad. Norconsult, that had even conducted detailed engineering study for the project, is also the consultant during the period of construction. Cement solution is being poured in the foundation as per its latest recommendation.
Design of headrace tunnel was also changed midway after weak rocks were found. The headrace tunnel, that was earlier constructed at a slope of eight percent, is now being constructed at a slope of 0.3 percent. Additional experts were brought even to study for the tunnel. The project’s schedule was extended by six months due to the change of tunnel’s design while project cost has also increased by around Rs 1 billion.
Source : Karobar Daily