Roads: Works to stabilise the Reutala slide, which is infamous for perennial roadblocks began recently.
Works and human settlement (MoWHS) minister Dorji Choden visited the area in September last year, following which the Department of Roads (DoR) and Department of Geology and Mines conducted a study following directions from the ministry. The report was submitted recently with recommendations on short-term measures to contain the slides.
“They have already started the drainage works,” DoR design division chief engineer Lungten Jamtsho said.
Reutala, which is on the way to Zhemgang is located around 84km from Trongsa. Reutala is dreaded by travellers as frequent landslides occur there especially during the summers. The slides at Reutala have even taken lives.
Vehicles are also damaged annually by the slides.
The blocks lasts for over seven months every year.
Keeping the 320m Reutala stretch open to traffic costs over Nu 4.7 million (M) on average annually. Yet, the slides reoccur the next year.
Lyonpo Dorji Choden visited Reutala with the intention of finding a long-term sustainable solution.
During the visit, Lyonpo Dorji Choden told the media that a multi-pronged solution would be planned over the winter to address the perennial roadblocks at Reutala.
The report suggested that DoR begin with the construction of a French drain at the top of the slide area to control seepage.
The current slide is the reactivation of an old slide. “The main cause of the reactivation is seepage on the crown of the landslide,” DoR’s geo-technical engineer, Tempa Thinley said. “The seepage is actually acting like a lubricant to cause the landslide,” he added.
Earthquakes could also be one of the factors causing the slides.
If the seepage can be controlled, the slide could be contained to certain extent. The investigating team found no seepage on the landslide area between the crown and the road.
“The idea of French drain is to divert the larger amount of seepage to a stream nearby,” Tempa Thinley said.
The French drain will be constructed with a half perforated high-density polytene pipe, which will be covered with layers of gravel. On the surface, the drain will be covered with a geo-textile mat to prevent seepage of soil, which could cause blocks inside the drain.
Above the French drain a catch drain has also been proposed to collect the rainwater. The catch drain will help discharge the rainwater to the same stream.
The ministry has already asked the regional office in Trongsa to start the stabilisation works though there is no budget. “As of now the minister has asked to start the works with funding from overall savings from DoR’s budget,” Tempa Thinley said. “The works are supposed to be completed before the onset of the rainy season.”
The report has also recommended construction of a rock shed, which is a bridge of concrete beams or steel to withstand the impact of debris falling on it. But a rock shed will be costly.
“Constructing such structures would require more studies as to ascertain the type of the rock shed suitable for the area,” Tempa Thinley said.