Detailed Engineering Design and Tender Document Preparation of Tamakoshi V HEP (87 MW)


Funding Agency: Government of Nepal
Client: Nepal Electricity Authority (NEA)
Date: March 2017 – Sep 2018

Tamakoshi-V Hydroelectric Project is located in Dolakha District of Janakpur Zone in the Central Development Region of Nepal. The entire project area lies in Khare, Orang and Lamabagar Village Development Committees. The proposed project is conceptualized to develop as a tendom operation project with Upper Tamakoshi HEP. The intake site/ underground interconnection system with Upper Tamakoshi tailrace outlet is located in Lamabagar VDC at an elevation of 1155 m, whereas the underground powerhouse lies at the right bank of Tamakoshi River just downstream of the Suri River confluence with Tamakoshi River at an elevation of about 990 m. Tamakoshi V Hydroelectric Project is cascade development of Upper Tamakoshi Hydroelectric Project.

The main components of the project are as follows:

  1. The installed capacity is 87 MW.
  2. Interconnection system comprising a connecting tunnel, spillway, spillway outlet tunnel and headpond for providing required submergence head for headrace tunnel;
  3. Water conveyance system consisting of concrete lined headrace tunnel of length 8,215 m and finished diameter of 5.6 m;
  4. Orifice type Surge tank at the end of headrace tunnel of internal diameter 15.0 m and height of 98.0 m;
  5. An underground powerhouse of dimension 50.0m x 16.0m x 31.0m (L x B x H);
  6. 61 m long tailrace tunnel, and 54.55 m long tailrace canal;
  7. An outdoor switchyard in two terraces with size of 80 m x 40 m at the lower level and 40 m x 40 m at the higher level;
  8. The proposed project is envisaged to produce a total energy of 428.3 GWh.


Actual Service Provided by the firm within the assignment:

The scopes and objectives of the consulting services will include, but not limited to following:

  1. Review of Feasibility Study and other available relevant reports/data, documents and indentify the gaps in data,
  2. Prepare topographic maps for powerhouse site and other project areas as necessary,
  3. Excavation of Test Adit at powerhouse site
  4. Prepare Detail Engineering Design of the project components,
  5. Prepare quantity and cost estimate and construction plan,
  6. Review and update EIA study carried out by NEA including but not limited to preparation of resettlement plan, environmental management plan, impact on vulnerable communities, flora, fauna etc. if any to finalize EIA and SIA studies/assessment for fulfilling the requirements of GoN and lending agencies,
  7. Analyze financial structure, financing plan and recommend the most appropriate structure/plan
  8. Analyze and recommend appropriate institutional arrangement for project implementation.
  9. Inception of Assignment
  10. Field Investigation and Data Collection for Engineering/Environmental Studies
  11. Hydrological, Sedimentological (Geological), geotechnical and Hydraulic Studies
  12. Review on location of powerhouse and tailrace and interconnection system design
  13. Detail Engineering Design, Specifications and Drawing along with the safe interface between already constructed interconnection tunnel and headpond
  14. Power Evacuation Study
  15. Construction Planning and Scheduling inclusive of construction power Supply
  16. Economic and Financial Analysis of the Project
  17. Environmental Impact and Safeguard Studies
  18. Preparation of Complete Tender Documents & Tender Drawings
  19. Analysis of Institutional Arrangement for Project Implementation
  20. Responsibilities of consultants also includes construction of 170 m long Test Adit tunnel (D shape 2.5 m x 2.5 m