21 January 2017
Xekaman 3 hydroelectric plant in Laos: a very major landslide in December
The Xekaman 3 hydroelectric power station in Laos is a 250 MW dam, tunnel and associated infrastructure located at 15.375N 107.407E, close to the border with Vietnam. Built between 2006 and 2010 at a cost of US$273 million, 90% of the electricity generated is exported to Vietnam. Fairly soon after completion the dam started to be plagues by landslide problems, not at the dam site but at the penstock, which it appears was constructed on an ancient landslide without adequate measures being taken to provide stability. There is a nice paper providing details of the landslide affecting the Xekaman 3 penstock online here (NB this is a PDF).
Problems appear to have started soon after the reservoir was filled, and the paper reports multiple movement events, mostly with reasonably small displacements, that caused major damage to the penstock and associated pipelines. At one location it appears that a sinkhole has opened up, and there is also a reference to a new channel being formed. The paper notes that work was ongoing to try to solve the landslide problem; in the meantime a telescopic section of pipe was installed into the pipeline to try to accommodate movement. The paper includes the photograph below of the site. Note the re-engineered walls and structures. Note also the red-roofed powerhouse at the toe of the slope – this is a key structure in the most recent event:
At 8:45 am on 16th December a major failure occurred on this slope, which has destroyed the penstock infrastructure. Radio Free Asia has a report about the landslide, which states that:
A break in a critical waterway shut down a hydro-electric dam in southern Laos and raised questions about the quality of construction at the facility that sends most of the power it generates to Vietnam. While officials said the Dec. 16 break in the Xekaman 3 facility’s penstock posed no threat to people living downstream, it marked the second breakdown in the tunnel that channels water to the power turbine, RFA’s Lao Service has learned.
“The broken portion of the pipe is about 100 meters from the power house,” said an official who spoke on condition of anonymity. “Rocks and mud flowed into the power house.”
According to the official, the damage is extensive as the power house and its equipment were inundated.
“The dam is no longer operational,” the official told RFA’s Lao Service. “Power production is stopped.”
Perhaps the most interesting element though is a photograph of the site, also in the report:
The almost completely buried building is the power house at the toe of the slope. This was clearly an exceptionally serious, and expensive, landslide.
I have written both here and in a paper about the evidence that many of the major hydroelectric schemes under construction across Asia are taking inadequate consideration of landslides. This event reinforces my view. I continue to fear that we are heading for a tragedy.