Upper Kotmale Field Visit - Copy

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INTRODUCTION

Achieving another milestone in the country’s development drive, the longest tunnel which

would carry water from the Kotmale reservoir to the underground power station under the

Upper Kotmale Hydro Power project which adds 150 MW of power to the national grid has

been started its rising and will provide the full power by the time of next March.

This project which is estimated to cost Rs. 44 billion is funded by the Government of Japan

and Ceylon Electricity Board. The construction of the project commenced in 2006.

This concept of the project was first mooted by the Sri Lankan authorities in 1968 under the

Mahaweli scheme. But this project was not implemented under the accelerated Mahaweli

Development Scheme of the UNP Government.

As per the provision in the National Environment Act of 1998, the Environment clearance

was granted to the Upper Kotmale Power Project. There were several objections to the

project initially and they were settled by the courts of law. The project was implemented

under five phases.

The Japanese Government provided a loan of Japanese Yen 33,265 million while the CEB

makes an investment of Rs 5,931 million for the project.

It is targeted to generate 409 GWH of electricity annually by this project and the installed

capacity is 150MW. The dam will be constructed across the Kotmale stream. The length of

the dam is 180 meters and the height 35.5 meters.

SPECIALITY ABOUT THIS POWER PLANT

This is the 2nd underground power house and the 2nd run of the river hydro electricity

system in Sri Lanka. Also this is counted as the longest headrace tunnel in the country and

the last large scale hydro project happening in the country.

The type of the dam is gravity Dam and it has five spillways and also has a Hydraulic head

of 473 m (1,552 ft).

GENERAL SPECIFICATIONS

1. Turbine : Two 77,000 kW vertical shaft Francis type turbines

2. Generator : Two 88,000 kVA alternating current generators

3. Overhead Traveling Crane : Double trolley, Two 75 T main Hoists and two

(2) Mono rail hoists

4. Power Transformer : Two 88,000 kVA Indoor, Special three-phase,

oil immersed transformers

5. Switchyard Equipment : Outdoor Type 245 kV SF6 gas insulated metal

enclosed switchgear



6. Power Plant Equipment : Protection Relays , Unit Local Controllers, 110 V

Dc supply system, 400/230 V AC Power supply, 33kV and 13.8 kV Metal Enclosed

circuit breakers, 33kV Power Cables and Control Cables

PROJECT HISTORY

The project was initially planned in 1968 by

the local authorities, before

the Government of Japan funded a study

between 1985 and 1987 to further examine

the hydroelectric potential in the upper

reaches of Kotmale River. The feasibility

study included five sites and eight

alternative development schemes, and concluded with two sites which were more

technically and economically feasible.

The two sites were a conventional type at Caledonia, and a run-of-the-river type

atTalawakele. The project at Caledonia involved the displacement of over 2,700 families

and inundation of large areas of land used for tea plantations, and thus the Caledonia site

was dropped. Further funding was then provided by Japan for the engineering study,

which included a review of the feasibility study, selection of an optimal development plan,

development of the detailed design, and the preparation of tender documents and anenvironmental impact assessment report.

The environmental impact assessment report was completed in September 1994, with the

final design report completed in March 1995. The environmental assessment identified key

issues associated with the project, which includes impact on St. Clair's Falls aesthetics due

to stream flow reductions, social impacts due to resettlement of affected people, possible

effects on ground water due to tunneling, impacts on downstream water uses due to de-

watering of streams, and impacts on biodiversity. These impacts led large delays in project

development.As per the National Environment act, the environmental clearance was then granted to the

project. The project initially faced several objections, before being officially permitted by

courts of law. In further the Government agreed to the people to give them new houses,

schools, temples, churches, hospitals, basically almost all re-civilization agreement. After

that they had begun the constructions of the major Hydro project.



SPECIFICATIONS OF WATERWAYS

Water Source : Kotmale reservoir 800,000 m3 (28,000,000 cu ft) (Making a

reservoir across the Kotmale river by using a dam)

Main Intake Dam : Gravity Dam (With a Height of 35 m(115 ft) , Length of 180

m(591 ft) and Crest Width of 7 m(23 ft))

Headrace tunnel : This is the main tunnel which supplies water to turbines. This

is almost circular shape with 4.5m-5.2m of diameter and 12890m long. The tunnel

goes through a rocky mountain which does not need additional supporting concrete.

Therefore concrete lining requirement is less. Upstream surge tank: This is for protection of the headrace tunnel from high water

pressure caused by sudden shutdown of the power plant. This is 12m of diameter

and 98m of high.

Underground inclined shaft for penstock: The penstock is underground due to

reduce losses and the cost of construction. The penstock having 4.5m-1.45m of

diameter and 791m long.

Draft tunnel : This is 78m long tunnel with 3m of diameter and circular

shape

Downstream Surge Chamber: 58m high and 8m of diameter.

And also there is a tunnel for maintaining a periodic continuous flow of water for

St.Clair waterfall and downstream uses.

SCOPE OF WORKS

Site preparations, construction of employers and workers living quarters,

construction of access roads, and relocation of affected people.

In this session Building access roads with drains, culverts and bridges to the respective

construction site. In here the improvement of existing road was also done.

All key civil engineering works, such as construction of tunnel, dam, underground

power house etc. This takes about 50% of the project cost.

In this section Constructing and providing the Employer and the Engineer with adequate

facilities such as Residential Houses, Office Complexes, and Recreation Facilities etc was

also included.

Providing permanent Facilities for the Re-settlers



This consists of constructing and providing permanent facilities for the persons affected

by the project. The re-settlers are mainly estate workers but include a good number of

varied occupants, shop owners, workshops, garages etc. Their new houses was planned to

construct in an area which is close to their residential places .And also For a village a new

school, a new hospital, a new cinema hall were to be constructed. The resettles have now

being offered modern new homes with most of the common facilities (electricity, Water

supply) and some of them have great sceneries and views to their homes.

Hydro-mechanical works such as construction of spillways, penstocks, intake

gates, etc.

Main intake dam consists of construction of River Diversion Works, Intake Dam, Control

Building, Land Reclamation Works and Road and Bridge Works and Water ways consists

of construction of Headrace Tunnel, Upstream Surge Tank, Shaft for Penstock, Draft

Tunnel, Downstream Surge Chamber, Tailrace Tunnel and Outlet.

Building 33 kV Construction Supply line and concrete Pole lines of capacity 20 MW and

10 MW respectively for each circuit including 21 km 33kV Lynx conductor double circuit

tower line from Nuwara Eliya Grid Substation to the Niyangamdora power house and

11.5 km 33kV Lynx conductor double circuit tower line from Henfold to Talawakele intake

dam via Lidula Gantry to supply the Talawakele Intake dam.

POWER TRANSFORMER

Three single phase transformers instead of three phase transformer because for

installing a three phase transformer requires lot of area.

Those are oil immersed transformers.

There is a spare oil tank and oil treatment system.

In case of a fault, the oil composition would be changed and according to the

composition we can find the internal fault.

SWITCHYARD EQUIPMENT AND TRANSMISSION LINE

There is an outdoor type gas insulated metal enclosed switchgear and also there is

a conventional switch gear at switch yard.

The transmission line is designed to construct 220kv XLPE power cable. But it is notfinished yet



Facilitators : Mr.Shavindranath Fernando

: Mr.R.S.W.Wagarachchi

References : wikipedia.org/wiki/Upper_Kotmale_Dam

: dailynews.lk/2010/11/05/news02.asp

: development.lk/news.php?news=828

Spillway and Intake gates

Access Tunnel Turbine

Rotor

Transmission Tower



UPPER KOTMALE HYDROPOWER PROJECT

FIELD VISIT REPORT

NAME : Isuru Kasthurirathne

INDEX NO : 090253H

DATE : 23,09,2011

Department of Electrical Engineering

Upper Kotmale Field Visit - Copy

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