An overburden of a local slide near the Punatsangchhu Hydroelectric Project I (PI) dam site construction occurred on the morning of January 22, taking away an excavator, injuring the operator and damaging concrete piles and cable anchors.

The slide occurred after engineers and the PI management assured last month that a solution has been found to the slide and that they are widening a stretch of the Wangdue-Tsirang highway to remove a portion of the local slide.

Sources said the area sliding even after five years of the initial disaster in July 2013 after the right bank of the dam site slid by more than five metres is worrying.

“This sliding would again delay the works,” a source said. “We have also detected some cracks uphill, which is more worrying.”

 The overburden before the slide

The overburden before the slide

While the PI managing director, NC Bansal, said he was in meeting the whole day yesterday and that he would send the response to media queries today, the project manager for the construction company executing the dam construction, Larsen and Turbo (LNT) said they would have to study how grave the slide is. “We cannot say anything until a proper study is conducted.”

PI officials said the managing director and director (technical) advised them to wait for the designer, Centre Water Commission’s (CWC) advise to clear the slides.

An official explained that CWC initially advised them not to remove the overburden, as it is out of the dam area but again advised them to remove it last November. “This slide occurred when we were trying to remove it.”

Meanwhile, the construction of the project started in November 2008 and was supposed to complete by November 2016. Works got delayed after the slide in the dam site in 2013 and the local slide in 2016.

Some engineers working for the project told Kuensel last December that all is not well, reasoning that a third party expert the management hired, the Norwegian Geological Institute (NGI) did not provide a concrete solution.

They shared that when the first major slide occurred, the consultant, Water and Power Consultancy Services (WAPCOS) had assured that they handled more severe problems and they would resolve it.

Engineers then said there was nothing much they could do, as they have to depend on external agencies for the remedies.

NC Bansal then acknowledged that addressing the slide continues to pose a challenge, but said the management, in association with its consultants (WAPCOS, CWC, GSI) has analysed the cause of the slide through detailed subsurface investigations based on which a number of stabilisation measures have been implemented or are under implementation in a phased manner over a wide reach of dam area.

He also said to monitor the slide in real time, an IBIS Radar has been installed at the project site in July 2018 and the data is being continuously analysed by CWC, NGI and PHPA-I based on which further protection measures are being taken.

However, there are observers who claim that as the slide glides the management would be forced to treat it. “The damage appears to be restricted as of now and did not extend to the highway or the main dam body,” a source said.

Tashi Dema


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