Sri Lanka – The Upper Kotmale Hydropower Project


Region: Asia - South Asia
Country: Sri Lanka
Location within Country: Nuwara Eliya District
Client: PKII was a sub-consultant of Nippon Koei for the Ceylon Electricity Board (CEB)
Funding Source: Japanese Yen Loan
Date: November 2003 - March 2013
Category: Energy and Power
Service: Detailed Engineering Design, Technical Assistance, Construction Supervision

Constructions Overview

Narrative Description of Project:

This project will construct a runoff-river hydropower plant (150 MW) on the Kotmale River, a tributary of theMahaweli River (upstream from the existing Kotmale Dam), to meet the need for power demand after 2008 in an environmentally and socially sound manner.  By meeting the increasing demand for power, the project aims to contribute to the country’s economic growth.

The water of Kotmale Oya will be diverted at Talawakelle intake dam, into the headrace tunnel (length = 12.5 km), and then to the power house, which is located at about 2 km upstream of the confluence of Puna Oya and Kotmale Oya (the upper end of Kotmale Reservoir).  A 220 kV double circuit transmission line will convey the electricity to the existing Kotmale Switchyard with a 17.5 km length of transmission line.

Main Project Features:

– Installed Capacity, Annual Energy:        150 MW, 528 GWh

– Dam , Type, Height                        :        Concrete Gravity, 35.5 m

– Headrace Tunnels Length, Diam  :        12.5 km, 4.5 m

– Tailrace Tunnel; Length, Diam.     :        0.46 km, 4.5 m

– Powerhouse Type, Dimension      :        Underground, W 19m x L 50.5 m x H 36.5 m

– Turbine                                            :        Francis Type, 2 Nos. , 75 MW/Unit

– Plant Discharge, Rated Head        :        36.9 m3/sec, 473.1 m

– Transmission Line                          :        220 kV, 17.5 km

Description of Actual Services Provided in the Assignment:

  1. Preparation of the completion report regarding the intake dam, including intake structure and the head pond (reservoir) which includes (i) preparation of summary of design history; (ii) compilation of design revision reports during the construction stage; and (iii) compilation of working records of contractor’s and consultant’s activities;
  2. Assist in the review of as-built drawings and evaluation of contractor’s claims.


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