Lao Dam Collapse Due to Use of Soil: Water Experts

Poor construction methods, with soil used in place of concrete, caused a fatal hydropower dam collapse last year in Laos, a panel of water experts has concluded, prompting a rejection of its findings by the South Korean firm that built the project.


라오스 "보조댐 붕괴, 막을 수 있었다"...SK건설 "과학적 근거없어 동의 못해"

   지난해 7월 라오스 남부에서 대규모 인명 피해를 낳은 수력발전소 보조댐 붕괴사고가 불가항력적인 것이 아니었다는 조사결과가 나왔다. 

이에 대해 시공사인 SK건설은 과학적 근거가 결여된 조사결과라며 동의할 수 없다고 공식 입장을 발표했다. SK건설이 반발하면서 조사결과를 놓고 상당한 갈등이 예상된다. 

라오스뉴스통신(KPL)에 따르면 라오스 국가조사위원회는 28일 세피안-세남노이 수력발전소 보조댐 붕괴사고에 대한 독립전문가위원회(IEP) 조사결과, 불가항력적인 사고로 볼 수 없다는 결론이 나왔다고 밝혔다. IEP는 지난해 7월 23일 발생한 붕괴사고 전 며칠간 집중호우가 쏟아졌지만, 붕괴가 시작됐을 때 댐 수위가 최고 가동 수위에도 도달하지 않았다면서 이 같은 결과를 내놨다.

이에 대해 SK건설은 공식 입장문을 통해 "IEP 조사결과는 사고 전후 실시한 정밀 지반조사 결과와 일치하지 않는 등 과학적, 공학적 근거가 결여돼 있다"면서 "조사결과에 동의할 수 없다"고 반박했다. SK건설 측은 "IEP는 자체적으로 자신들이 지정한 위치, 방법론, 제3의 분석기관을 통해 토질 분석을 실시했다"면서 "IEP의 주장대로 누수로 인한 침식이 원인이었다면 대량의 토사 유출이 목격됐어야 하는데 그러한 사실이 없다"고 설명했다. 



라오스댐 붕괴 원인 "SK건설 과도한 설계변경·공기단축"

edited by kcontents

또 SK건설 측은 "이번 조사에 옵서버로 참여한 한국 정부조사단을 포함한 세계 유수의 엔지니어링 전문업체들도 IEP가 밝힌 사고 원인에 동의하지 않고 있다"고 덧붙였다. 

[박윤예 기자] 매일경제

edited by kcontents

The disaster occurred on July 23, 2018 when a saddle dam at the Xe Pian Xe Namnoy (PNPC) hydropower project collapsed following heavy rains, inundating 12 villages and killing at least 40 people in Champassak and Attapeu provinces, leaving many more missing.

On Tuesday, the government of Laos confirmed earlier reports that a panel of international experts had determined the construction of the saddle dam was “substandard,” and the soil used to build it was “the cause of the collapse,” according to state media.

“The International Expert Panel (IEP) found that the major cause of the Xe Pian Xe Namnoy dam collapse was the high-absorbency of the foundation of saddle dam D, coupled with soil being porous and easily eroded, and the level of rising water,” Singpheth Bounsavathiphanh, vice chairman of the Government Inspection Authority and vice chairman of the Lao National Investigation Committee told reporters in Vientiane.

“Those conditions caused erosion within the foundation … When the erosion reached a certain level, the dam became unstable and sliding began at the higher saddle dams. At some point, saddle dam D broke, causing a massive amount of water to flow out of the reservoir.”

Earlier this month, an official with the dam project told RFA on condition of anonymity that the IEP had determined the dam collapse was the result of poor construction and the use of soil instead of concrete in a report it submitted to the Lao government in March, which also recommended that all other saddle dams at the site of the disaster be built with concrete.

At the time, Singpheth Bounsavathiphanh told RFA that government officials had received the report in March, but couldn’t disclose its findings “because they are in the process of negotiating with the South Korean government about what information should or should not be released to the public.”

PNPC is a consortium formed by a local Lao company and South Korea’s SK Engineering & Construction, and Korean involvement in the project had earlier prompted Seoul to send relief teams to Laos to help mitigate the effects of the disaster.

Findings rejected

Shortly after the release of the report on Tuesday, SK Engineering & Construction dismissed the IEP’s findings and questioned the scientific basis of its approach.

“The IEP itself conducted soil analysis through its designated location, methodology and third-party analysis and the final data did not [support its conclusion],” a spokesperson told South Korean media.

“If the destruction was a result of what the IEP claimed, a large amount of soil leakage should have been found at the bottom of the saddle dam before the accident, but that was not the case.”


A man wades along a flooded road at a village in Attapeu province, July 26, 2018.

SK Engineering & Construction noted that teams sent by both the South Korean government and by a group of leading engineering firms to investigate the cause of disaster, at the behest of the government of Laos, “initially had different opinions” from those included in the IEP report.

“Unlike the IEP, the teams have suggested that the cause of the accident is difficult to determine,” the spokesperson said.

In the meantime, a new saddle dam is now under construction at a location a little more than a kilometer (two-thirds of a mile) away from the dam that failed, and officials have said that the new 400-meter-long (1,312-foot-long) structure will be built with concrete and anchored at a depth of at least 10 meters (33 feet) into the ground.

In the wake of the Xe Pian Xe Namnoy disaster, Laos has stepped up scrutiny of an ambitious hydropower dam building program under which it aims to serve as the “battery of Asia” and sell hydropower to its more industrialized neighbors China, Thailand and others.


Posted by engi, conpaper Engi-

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