SALWEEN WATCH HOTMAIL OUT

BACKGROUND DOCUMENTS RELATING TO THE SALWEEN MEGADAM

Salween Watch

Date: 17th May 1999. Vol. 2

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Plans to build the Salween Dam at Ta Sang in Southern Shan State

A translation of a report issued by the South-East Asia River Network on March 8, 1999 (Note: In translation from Thai to English, some details may have become unclear.)

Size and Type of Dam

The Ta Sang dam project is currently in the pre-feasibility study stage.

According to preliminary studies, the dam will be built on the Salween River in the southern part of Shan State in Burma, near to Ta Sang, which lies 370 km east of Taunggyi, and about 130 km from the BP-1 Thai-Burma border crossing.

This project will be located somewhere between 12 km north of the Ta Sang ferry crossing and 5 km south of the ferry crossing. This area is mountainous and the river is narrow, passing through steep sided gorges.

The river bed consists of layers of sandstone and siltstone, suitable for construction of either a concrete faced rock-fill dam (CRF dam), a roller compacted concrete dam (RCC dam), a gravity dam, or an arch-gravity dam.

The type of dam built will depend on the land on either side of the site. The electric power generator will be at the base of the dam.

The latest results of the survey show that the full supply level (FSL) will be between 320-370 metres above sea-level. At each site there can be an installed electricity production capacity of between 1,500-5,000 megawatts. The sites have been chosen because of their access to roads from BP-1 and the fact that they can send 500kV AC to join the Burmese grid and 500 kV DC to Thailand.

This project will involve building another dam downriver to control the water that is released from the turbines 16 hours a day, 6 days a week.

One cost of the project may involve having to move the bridge at Ta Sang up to Kunhing on Highway 4.

From the survey, the two most interesting plans are to build an RCC and electric power generator at site 840, 6 kilometres north of Ta Sang, and at site 725, 2 kilometres south of Ta Sang. However, there is still not sufficient geological data to make a final decision.

One plan is to build a CFR at site 840, with an underground generator (this kind of dam is very common in Japan.) The site and type of dam will depend on the geological survey and drilling during the feasibility study.

Level of water

The water level has been chosen at 350 meters above sea-level. The higher the level, the more possibility for attracting investment. However, the engineering survey, the social and environmental impact assessments and the amount of water will all be factors affecting the chosen level.

The size of the generators

The assessment shows that the lowest energy generation may be between 2,500 to 4,000 megawatts. A quarter of the electricity produced will be sent to Burma. The rest will be sent to Thailand.

If there are 6 turbines, each would produce 550 megawatts. (6x 550 = 3,300 megawatts.)

The cost and duration of the project

The CFR project at site 840 will cost 3,397 million US dollars, and take about 6 years. The RCC dam at site 840 will cost about 3,076 million US$ and at site 725 will cost 3,316 million US$, and will take about 5 years.

The details about the respective dams can be summarised as follows:

• Project at Project at Project at
  site 840 at site 840 at site 725
• Type of dam CFR dam RCC dam RCC dam
• Site in relation to Ta Sang 6 km north 6 km north 2 km Southof Ta Sang of Ta Sang of Ta ang
• Size of catchment area 207,000 km2
• Average flow rate 2,583 cm3/sec
• Full Supply Level 350 m above sea level
• Max. reservoir surface area 660 km2
• Reservoir highest storage volume 36,100 km3
• Highest live storage volume 14,200 km3
• Max. height of dam 188 m 193 m 190 m
• Dam crest length 768 m 783 m 955 m
• Rate of water flow into turbines 430.5 cm3/sec
• Head of turbines 142 m 145 m 147 m
• Installed capacity (in megawatts) 3,327 3,399 3,434 including all 6 turbines
• Electricity to be produced 16,076 Gw 16,136 Gw 16,307 Gw (in gigawatts / hour) per year at upper dam
• Electricity produced 6,930 Gw 7,923 Gw 8,001 Gw per year at lower dam (gigawatts/hr)
• Total electricity produced 23,005 Gw 24,059 Gw 24,308 Gw per year (Gw/hr)
• Cost in US Dollars $3,397,000,000 $3,075,000,000 $3,316,000,000
• Length of time to build 6 years 5 years 5 years
  
  Note: The Electricity Generating Authority of Thailand has been contacting academics in Thailand to conduct an EIA for the project.