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Detailed Investigations and Engineering Design of Sunsari Morang Irrigation Project Headworks

Funding Agency: Government of Nepal
Client: Sunsari Morang Irrigation Project, Department of Irrigation
Date: 15 July 2017 – 15 January 2019

The main objective of the consulting service is to prepare the detailed engineering design and procurement documents of SMIP headwork at Chatara. The specific objectives of the services are to:

  1. Assess the appropriate type of diversion headworks to meet the irrigation water requirement of SMIP;
  2. Carryout Prefeasibility studies if areas in the eastern (Sunsari and Morang districts) and western (Saptari & Siraha district) bank of Koshi river that could be irrigated with diversion headworks;
  3. Carry out detailed topographical survey of headwork site;
  4. Carry out detailed geo-technical investigation of the head work and associated structures including necessary sub-surface explorations and tests;
  5. Carry out hydrological survey and water resources assessment of the Koshi river including
  6. study on sediment transport and management;
  7. Carryout detailed investigation of the existing infrastructure of SMIP up to Hydropower at 8.5 RD including the possibility of hydraulic flushing of the settling basin with the diversion headworks condition;
  8. Carryout prefeasibility study of utilizing the drop in drain crossing at 52 RD of Main Canal (CMC) for generation of Hydropower including the hydraulic and structural assessment of Main Canal structures for conveying additional water for power generation;
  9. Prepare detailed engineering design of headworks including the regulation system (gates, lifting arrangements, electrification, etc. all complete);
  10. Prepare ICB procurement documents.

Actual services provided by the firm within the assignment:

The scope of services of consultants will include but not limited to following:

A. Selection of suitable headwork type

B. Detailed topographical survey

  1. Establishment of survey monuments;
  2. Benchmark survey;
  3. Traverse survey within the survey area;
  4. Topographical survey and prepare detailed topographic map in 1:1000 scale

C. Hydrological and Meteorological Data

  1. Review the past studies and decide the return period floods of the Koshi river for the hydraulic design of the headwork considering techno-economic importance of the project;
  2. Collect, review and update hydrological records of Koshi river at Chatra station for the assessment of the maximum design discharge, and minimum flow. Carry out frequency analysis of flood records using various statistical methods and tools;

D. Collection of Sediment Data and Suspended Load Sampling

E. Geological and Geotechnical Investigation

  1. Desk Study: Assessment of regional geological setting and preparation of the regional geological map for the project area in 1:25,000 scale with standard practices of geological mapping and Assessment of regional seismic setting.
  2. Engineering Geological Studies: Detailed geotechnical engineering and engineering geology investigation. Geological mapping sampling, testing and performing discontinuity surveys, Geological hazard mapping of the project area, detailed engineering geological mapping and cross section in barrage axis and intake locations, Permeability test in the headworks area, exploratory drilling/core logging.
  3. Geological Mapping of Project Area (Scale 1:10,000)
  4. Detailed Engineering Geological Survey: Engineering Geological Mapping (Scale: 1:10,000), Discontinuity survey, rock mass classification,
  5. Hazard Mapping: Probabilistic approach (1:25,000) for the project area, deterministic approach (physical based stability modeling 1:25,000)
  6. Geophysical Exploration: ERT Survey – carried out with SISCAL Pro multi-channel resistivity meter; Traverse Setting; Electric Resistivity Tomography (ERT) Layout.
  7. River Morphology and Sediment Data:

F. Preparation of Detailed Engineering Design and Tender Documents

  1. Detailed Engineering Design: hydraulic and structure design of headwork
  2. Preparation of Drawings/Maps: General Drawings: scale 1:25,000), Construction Facilities – scale 1:5,000; Diversion Facilities – scale 1:1,000; Headworks: scale 1:1,000
  3. Construction Planning:
  4. Cost Estimates
  5. Economic Evaluation
  6. Preparation of Tender Documents