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Salween Dam project details



The following is a translation of a report issued by the South-East Asia
River Network on March 8, 1999 on plans to build the Salween Dam at Ta Sang
in Southern Shan State

(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 feasability 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	Site 725 
				site 840	site 840
   
type of dam			CFR dam	RCC dam	RCC dam

site				6 km north	6 km north	2 km south
				of Ta Sang   of Ta Sang	of Ta Sang

size of catchment				207,000 km2
area

average flow rate 				2,583 cm3/sec

Full Supply Level				350 m above sea level

max. reservoir surface			660 km2
area

reservoir highest storage 			36,100 km3
volume

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				430.5 cm3/sec
into turbines

head of turbines		142 m		145 m		147 m


installed capacity		3,327		3,399		3,434
including all 6 
turbines (megawatts)

electricity produced		16,076		16,136		16,307
per year at upper dam
(gigawatts/hr)

electricity produced		6,930		7,923		8,001
per year at lower dam
(gigawatts/hr)

total electricity produced 23,005		24,059		24,308
per year (gw/hr)

cost (million US$)		3,397		3,075		3,316

length of time to build	6 yrs		5 yrs		5 yrs


Note: The Electricity Generating Authority of Thailand has been contacting
academics in Thailand to conduct an EIA for the project.