Detail Design Consulting (DDC) Services for Melamchi Phase 2 Contract No.: MDS/M2/C/03 (ADB Loan No. 3255-NEP)


Funding Agency: Asian Development Bank
Client: Melamchi Water Supply Development Board, Nepal
Date: Feb 2017 – Feb 2018

The primary objective of the Design Consultancy Services for Melamchi 2: Yangri and Larke Water Diversion Project is to provide services for engineering design including preparation of bidding documents for a project to divert 340 MLD water from Yangri and Larke rivers to the existing Melamchi Diversion Tunnel in order to ensure an integrated water supply system of 510 MLD capacity of treated water. The three main components of this project includes:

  • Access road: The access roads involve i) access from Melamchi to the confluence of Yangri and Indrawati, ii) access from the confluence of Yangri and Indrawati to the intake/portals of Yangri and Larke Rivers, iii) access to Yangri tunnel outlet near Melamchi headworks and to adit portal near Yangri and Timbu.
  • Diversion tunnel: Diverting water (170 MLD) from Larke River to Yangri River with 2.0 km of diversion tunnel. Diverting water (170 MLD) from Yangri River inlet besides another 170 MLD water from Larke River diversion to Melamchi River inlet with 9 to 12 Km tunnel.
  • Water Treatment Plant (WTP): Detail Design, Cost Estimates and bidding documents of WTP of 340 MLD.

Actual services provided by the firm within the assignment:

The Consultancy Services includes the following scope of works related to the above components:

  1. Review of previous study reports, collection of other relevant information, maps and identify the investigation required.
  2. Develop preliminary designs and costing of the various alternatives possible for the diversion scheme and access roads based on desk studies and site reconnaissance.
  3. Conduct field investigation/ studies including topographical, hydrological, construction materials, geological, seismological, and geophysical and geotechnical investigations/ surveys including core drilling of the project area for design of diversion and adit tunnels and portals, headworks, access roads, water treatment plants and camp facilities and infrastructures for the identified alternative/s.
  4. Prepare necessary topographic, geological and engineering geological, hydrological, maps for dam site. Tunnels, portals and access roads.
  5. Prepare Geotechnical Baseline Report for tunnels and landslide hazard map for access roads and assess risks of ground failures with and without mitigations.
  6. Carry out alternative configuration studies for the best option alignment, technology and implementation approach optimizing the use of available resources, for the design and construction of tunnel and access roads.
  7. Carryout details designs and prepare drawings and specifications for diversion and adit tunnels and portals, headwork, access roads, water treatment plants and camp facilities and infrastructures for the selected alternative.
  8. Prepare norms, rate analysis and cost estimates for improvement of design during construction, supervision of construction works, and construction, operation and maintenance of the entire project components.
  9. Carryout financial and economic analysis and feasibility study according to ADB Guidelines.
  10. Conduct socio-economic and economic analysis and feasibility study according to ADB Guidelines.
  11. Analyze and recommend appropriate institutional arrangement for project implementation by the Government.
  12. Prepare Construction Plan, Bidding Documents and Procurement Plan. The field investigations and detail design and tender document of the Access Roads shall be completed within the first five months from the start of the consultancy services so that bidding and contract award for the access roads can be completed within the consultancy period.
  13. Design and cost estimates for new road construction of 17.5 Km and upgrade of 4 Km access road, bridges of 70 m (long span) and 30 m (small span).
  14. Detail Design and Cost Estimates of selected tunnel alignment and the intakes, head works, weirs, diversion tunnel and Adit tunnels, tunnel outlets and all other necessary components. Also, includes hydro-mechanical works comprising trash racks, gates and stop logs in the intake and gates in adit tunnel & and diversion tunnel outlet.
  15. Detail Design, Cost Estimates and bidding documents of WTP of 340 MLD.

Besides, consultant is responsible for detail field survey, geological and geotechnical investigation (along with engineering geological mapping of Tunnel alignment, headworks area and access roads), socio-economic studies, Environmental Impact Assessment (EIA), Environmental Management Plan (EMP), preparation of land acquisition compensation and resettlement plan, social upliftment support plan, hazard and risk assessments, ground water investigations, review, modification and revisions of basic design.