TA SANG DAM PROJECT IN SOUTHERN SHAN STATE

Prepared by SOUTHEAST ASIA RIVERS NETWORK April 1999 Size and Type of Dam The Ta Sang dam project is currently in the pre-feasibility study stage. Preliminary studies indicate that the dam will be built on the Salween River in southern Shan State, Burma, near Ta Sang, which is 370 km east of Taunggyi and about 130 km from the BP-1 Thai-Burma border crossing. The project site will be located between 12 km north of the Ta Sang ferry crossing and 5 km south of the ferry crossing. This mountainous area features a narrow river passing through steep-sided gorges. The riverbed, consisting of sandstone and siltstone, is suitable for constructing 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 will depend on the geological conditions on either side of the site. The electric power generator will be at the base of the dam. Survey results show that the full supply level (FSL) will be between 320-370 meters above sea level. Each site could have an installed electricity production capacity between 1,500-5,000 megawatts. The sites were chosen for their road access from BP-1 and the capability to send 500kV AC to the Burmese grid and 500 kV DC to Thailand. This project will also involve building another dam downriver to control the water released from the turbines 16 hours a day, 6 days a week. One cost of the project may involve relocating the bridge at Ta Sang up to Kunhing on Highway 4. From the survey, the two most interesting plans are to build an RCC dam and electric power generator at site 840, 6 km north of Ta Sang, and at site 725, 2 km south of Ta Sang. However, there is still insufficient geological data to make a final decision. One plan is to build a CFR dam at site 840 with an underground generator (common in Japan). The final site and type of dam will depend on geological surveys and drilling during the feasibility study. Level of Water The chosen water level is 350 meters above sea level. The higher the level, the more attractive the project is for investment. However, the engineering survey, social and environmental impact assessments, and water amount will all affect the chosen level. Size of the Generators Assessments indicate 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, and the rest to Thailand. If there are 6 turbines, each would produce 550 megawatts, totaling 3,300 megawatts. 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 dollars and at site 725 will cost 3,316 million US dollars, each taking about 5 years. Summary of Dam Details: Detail Site 840 (CFR dam) Site 840 (RCC dam) Site 725 (RCC dam) Dam type CFR dam RCC dam RCC dam Location 6 km north of Ta Sang 6 km north of Ta Sang 2 km south of Ta Sang Catchment area 207,000 km² 207,000 km² 207,000 km² Average flow rate 2,583 m³/sec 2,583 m³/sec 2,583 m³/sec Full Supply Level 350 m above sea level 350 m above sea level 350 m above sea level Max. reservoir surface area 660 km² 660 km² 660 km² Max. reservoir storage volume 36,100 km³ 36,100 km³ 36,100 km³ Highest live storage volume 14,200 km³ 14,200 km³ 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 m³/sec 430.5 m³/sec 430.5 m³/sec Head of turbines 142 m 145 m 147 m Installed capacity (6 turbines) 3,327 MW 3,399 MW 3,434 MW Annual electricity production (upper dam) 16,076 GWh 16,136 GWh 16,307 GWh Annual electricity production (lower dam) 6,930 GWh 7,923 GWh 8,001 GWh Total annual electricity production 23,005 GWh 24,059 GWh 24,308 GWh Cost (million US$) 3,397 3,075 3,316 Construction duration 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. For more information about dams and water diversion projects in the Salween River Basin, please contact: Southeast Asia Rivers Network (SEARIN-Thailand)