Insight towards Hydroelectric Power from Uda Walawe to Samanalawewa

The primary purpose of this trip was to visit two different kinds of hydropower projects in Sri Lanka, to see the sites, equipment, mechanisms, etc. and learn about them. Enjoyed some other attractions on the way too. We got this opportunity as one of our friends is an engineer attached to Samanalawewa Hydroelectric power plant.

Before getting in to the details of the trip, I would like to illustrate some technical aspects related to hydroelectric power generation in a simple format for the ease of presentation as to how things go on. You all may know it but I still add this for the sake of completeness. (I’m not an ‘electrical person’ though). Here is a simplified diagram of a hydroelectric power plant

Diagram of a Hydroelectric power plant. Source: internet

Water is held in a reservoir built at a higher elevation. Water in the reservoir is then conveyed down under gravity using tunnels (But not necessarily. Tunnels are used if water has to be conveyed to a long distance) and directed to turbines using tubes called ‘Penstock’s. Water flow to the turbine is controlled by valves located in the power plant. Turbines are located in a power house constructed at a lower elevation. Difference of height between the water level of the reservoir and the outflow from the penstock is called the ‘Head’. Higher the head, higher the energy.

When the turbine is driven by the flow of water, it rotates the shaft at the centre of the turbine which is connected to the generator located in an upper floor of the plant. It rotates the rotor of the generator which then produces electricity. After driving the turbine, water is discharged down steam. This water may be utilized for irrigation or may be collected in another reservoir and used for power generation again.

Water flow, typical turbine and generator. Source: Wikipedia

Parameters of the ‘raw’ electricity generated are adjusted to required standards using transformers and connected to the national grid. A sophisticated control room is there to monitor and manipulate the operations of the whole plant.
Let’s get back to the trip now. We started in the morning around 6.00 a.m. and our first target was to visit the Uda Walawe power house before breakfast. When traveling along the road from Thanamalwila to Uda Walawe, you will see the dam and the two power houses located by the dam with a gap between each other.

Road on Uda Walawe dam – Disappearing in the infinity

The power house. There is another unit like this few hundreds of meters beyond

This power house is a unique one because it is the only one (In fact two units) of that type, located in Sri Lanka. Unlike the other power projects in Sri Lanka, this reservoir and the power house are located at the same elevation. This reservoir is built for the primary purpose of irrigation. When water is released to the main canal for irrigation, water is directed through a turbine and electricity is generated. So here, electricity is a ‘by-product’. Hence the power plant is operative for a limited time period of the year and the capacity is tiny, which is 3 MW.

The power plant visible to the dam is a multi storied building with a few floors under water where turbines, generators and related equipment are located. Although there is a control room for monitoring purpose, most of the operations are manual. Machinery is from former Czechoslovakia (Now Czech Republic).

Reservoir and the dam

Reservoir nearly dried up

View towards Balangoda from Uda Walawe power house. Note the penstock bringing water to Samanalawewa power plant – white line in the middle of the picture

Then we had our breakfast at CEB circuit bungalow, Uda Walawe. After that we went to see an amputated baby elephant at Eth Athuru Sewana, Uda Walawe according to a piece of information we have received. This baby elephant had been caught in to a trap and at the time wildlife officials reach there, the leg below knee had not been in a recoverable stage. Therefore the leg has been removed below knee. At the time of our visit, poor animal was struggling to walk with the aid of an artificial limb fixed by the officials there.

Still playful though just recovered from a surgery

Walking with the aid of the artificial limb

Hey, give me your camera…

Their feed

Exhibit under construction

Then we headed towards Uda Walawe junction and via A18 we reached Pallebedda. On the way we visited the place said to be the tomb of Pussadeva, one of the ten giants of king Dutugemunu. The place is somewhere between Uda Walawe and Pallebedda on A18 just by the road. A sign board placed by the provincial council is there.

Tomb of Pussadeva

Then from pallebedda we reached weligepola and turned right to Weligepola – Kaltota road to reach Kapugala where Samanalawewa power plant and ‘Kapugala Village’ (Where CEB quarters and Circuit bungalows of Samanalawewa project are located) could be reached.

On the way close to Weligepola

Finally at Kapugala Village

CEB Circuit bungalow in Kapugala Village was our place of stay for the night. We had a few relaxing hours and had some fun in the swimming pool too, before having lunch.

Had some fun in the swimming pool

After lunch we got back in to our vehicles with the idea of visiting the dam. We traveled on the ascending road with steep slopes and hairpin bends which took us to an elevation around 400m. From Kapugala, we reached Rajawaka junction and headed towards Pambahinna to reach Samanalawewa Dam.

Kapugala Village zoomed from Kapugala – Rajawaka road

Breathtaking scenery from Kapugala – Rajawaka Road. Note Uda Walawe Reservoir in the middle

Another ‘V cut’? Just like that in the jeep track from Kalupahana to Ohiya. This is Kapugala – Rajawaka road

Road from Rajawaka to Pambahinna

Close to the dam there is a site in which iron has been extracted from iron ore few decades back. The interesting thing is that, to heat iron ore in the process of iron extraction, they have used natural wind.

Site where iron was extracted from iron ore

Unlike the previous one, Samanalawewa reservoir was constructed primarily for generation of electricity. The dam is 110m high and 530m long and it is a rock filled dam. Water from the reservoir is sent to the penstock through a tunnel penetrating the mountains which is 5.2km long and has a diameter of 4.5m.

Massive dam

The gates zoomed

Massive spillway. Note the road along the slope of the dam. From the dam, can drive up to the edge of the spillway

On the dam

From the other end

Dam under construction (Curtsey: CEB)

From the road, the famous Samanalawewa leak could be observed. A water stream coming from the right bank of the reservoir is connecting to the spillway and flowing down. This has occurred due to a permeable area close to the right bank through which water penetrates and comes out as a stream from the right bank. Several measures have been taken to contain this and were so far unsuccessful. Water of the leak is now utilized for agriculture downstream and the leak is continuously monitored by a separate centre dedicated for it. Maximum water level allowed in the reservoir is 456m above MSL although it can hold water up to 461m above MSL as raising water level to maximum may have an adverse impact on the leak and thus involves an element of risk.

The leak. Stream coming out from the right bank. Note the dam connecting to the mountain at the top right hand corner

Looking down from the dam. Stream from the leak flowing under the bridge (at the middle) and connects to the spillway and flowing downstream

The sad side of the story is, although the power plant was originally designed to install four 60MW generators, after installing two of them the rest was abandoned due to limitations created due to the leak. If you observe the starting point of the tube which brings water down to the turbines (This could be seen when traveling on the road from Kapugala towards Kaltota) other than the tube can see a cap like structure fixed next to the penstock. This is the end of the second tunnel which could have been bringing water to the turbines that were not installed. Second tunnel and the space for the additional penstock and two generators are reserved there and one day we may see them functioning if the leak is prevented. At present 120MW is generated by the plant which would have been 240MW if the initial plan had worked. Would have been the largest individual hydro power generator complex of the country (Victoria 210MW)

The penstock. Water brought to the penstock from the reservoir through a 5.2 km long tunnel penetrating the mountains. Note the cap closing the tunnel end at the top and the space provided for a another penstock

The 5.2km long tunnel under construction on 21.11.1987. Railway used to take supplies in and to remove soil. Tunnel branching to right is an access tunnel. There had been a few of these and were closed after completing the main tunnel. (Curtsey: CEB)

We enjoyed the evening scenery of the reservoir and its surrounding. The VIP bungalow too could be seen from the dam.

VIP bungalow zoomed from the dam

Then we rushed to the VIP bungalow to enjoy the evening scenery. It is located on top of a mountain on the left bank of the dam. It was in a wonderful location and the scenery was simply breathtaking.

At once I got there it looked to me as a miniature of Heritance Kandalama. Balconies, stairways, railings, windows, rooms looking almost same. No surprise, little later I came to know that it was designed by the great architect Mr. Jeffry Bawa who was the designer of Heritance Kandalama. He has utilized his expertise to offer guests, the view of the surrounding at its best.

Evening scenery of the dam from VIP bungalow

Sun set from VIP bungalow

Colors of Samanalawewa

Since it was night, we were asked not to come back via the same route as elephants are hanging around in stretch from Samanalawewa to Rajawaka. So we had to take the route towards Pambahinna and reach kapugala via Belihuloya, Balangoda and Weligepola.

After spending the night at CEB circuit bungalow, our plan for next day morning was visiting Samanalawewa power plant. The premises was absolutely clean and maintained very well. The plant is a 5S award winner. It looked like that we were in a power plant in a developed country. Equipment and construction were by Japanese. The project had started in 1986 and commissioned in 1992.

At the time of our visit, plant was operative only in the night due to scarcity of water due to drought. We observed the equipment, systems, procedures etc. and had a memorable experience there.

Power plant complex. See the landscaping

Power plant under construction (Curtsey: CEB) – Click Image to Enlarge

A brand new turbine

Closer look

After that we went to see Diyavini ella which was just about 2 km away from the power plant towards Kaltota. The falls can be viewed from the road just after passing Diyavinna School. Water level was very low due to drought.

Poor Diyavini Ella

Then we again went to VIP bungalow to enjoy the scenery during day time. We stayed there for a couple of hours and started on the return journey around 12.00 noon.

VIP Bungalow: A corridor during night

Lobby

Inside a room. What a view…

The roof top

Scenery from VIP bungalow

More scenery

Breathtaking

Dam as seen from VIP bungalow

We traveled to Pambahinna and turned right towards Haldummulla on A4. On the way we visited Surathalee ella. To the base of the fall it is only 50m walk inside and there is a sign board at the bend in A4 where the turn off is located. Top part of the falls could be seen from A4 road.

Surathalee

Lower part of surathalee ella

After moving a few km from kalupahana, it started raining heavily. I must say ‘it rained cats and dogs’. Within the heavy rain any how we managed to stop at a road side café close to Haldummulla and have some rotti and lunu miris for lunch and a hot cup of tea.

We again got into vehicles and moved towards beragala. Rain was continuing at the same strength and our driving speed was very slow. After passing beragala, towards wellawaya, mist started settling in and again had a hard time to penetrate the mist. Due to rain held for hours, roadside cascades were roaring in full flow just like attempting to wash away the road and the surrounding.

Penetrating mist

Roadside cascades roaring in

The road from Beragala to Wellawaya is not carpeted and it is a rough road. Can be managed by any common car and only thing is that you can’t speed up a lot. It has enough space for two vehicles to cross. At the times of heavy rains driving here involves some risk as landslides are possible.

It was still raining when we reached Koslanda. I was eagerly expecting to see how Diyaluma would look like after a few hours of heavy rain as I have never encountered such an experience. Once we got close to the falls I could not believe my eyes. I have never seen Diyaluma in this manner. Water flow was huge and the bottom part was covered by a thick wail of fog. We at once got out of our vehicles and went to the observation platform. The fog flowing in was wetting us completely. The rain was also continuing but not as heavy as before. While we were watching the falls, water level increased little by little. We were completely wet like ‘diyabariya’s but watched the glorious view for about one hour.

Water level increased little by little: Here we go… One

Two

Three

Four

Five	Getting down lightning fast

Weil of fog