LG officials recommend a bridge from near the stretch crossing Mao Chhu
The Department of Roads (DoR) office in Sarpang is planning to construct four check dams at Aieslip, a common roadblock site along Gelephu-Trongsa highway to ensure improved road connectivity during monsoon.
Officials said four 10 metres high reinforce concrete check dams would be constructed at Aieslip, maintaining 20 to 25 metres distance between the wall-like structures.
The check dams are expected to control the flow of debris and slow down the runoff at the flood-prone area.
Officials also said while it would be the first of its kind in the country, the mitigation structure is the best option and cost-effective control measures built at the geologically fragile slope and rainfall-induced slope failures.
DoR’s chief engineer in Sarpang, Sonam Tashi, said earthquake fault line runs through Aieslip areas, making the place more vulnerable to landslide and flash flood during monsoon.
“The landslide at Aieslip was more of scaling of debris as a layer of hard rock was found at five to six metres depth,” he said. “ Core drilling confirmed the slopes were unstable. There is a need to control the scaling of the debris.”
According to the chief engineer, planned control measure was economically viable, faster, and would also protect the existing structure along the highway. “The slope instabilities at Aieslip were rainfall-induced and the landslide mostly because of debris formation.”
Works are expected to begin in the upcoming fiscal year.
A detailed geotechnical investigation of landslide conducted for seven months recommended construction of check dam at Aieslip.
DoR spends Nu 2 million annually at Aieslip just to clear the road for traffic, according to the study.
A study conducted at Aieslip stretch states that the undercutting of the slope’s base by swollen Maokhola had further aggravated the slope condition. This resulted in more recurring expenditure annually. The area of slope affected by a landslide is about 50 acres.
The seven-month long study was conducted at the cost of Nu 1.9 million.
The construction of four check dams, slope drain, and riverbank protection is expected to cost Nu 30 million, according to the officials from DoR.
The frequent roadblocks at Aieslip, located over seven kilometres away from Gelephu town had been a problem to commuters from Trongsa, Zhemgang, and four gewogs of Sershong, Chuzergang, Umling, and Tareythang.
Local government officials from Umling, Sershong, and Gelephu discussed the need to improve the stretch at Aieslip, especially during monsoon during the dzongkhag tshogdu in April.
Umling gup, Ugyen Norbu, said the government had to spend a huge amount every year at Aieslip and people were affected by the roadblock day and night.
“Constructing a bridge over Mao Chhu near Aieslip would be more reliable. We never know when the Aieslip slope would be stable,” he said.
He also said that the base of the bridge at Sershong has weakened and it has become risky too. “It might cost a bit for the construction but it would be a one-time expenditure and reliable,” said Ugyen Norbu.
According to the study conducted by a consulting firm at Aieslip, the government spends more than Nu 700 million annually in the country just for emergency restoration of roads. DoR officials, however, said the figure is wrong.
By Nima | Gelephu
Edited by Tashi Dema