Water supply to about a thousand households in Tangsibji, Trongsa was cut off on June 26 after works at the Nikachhu hydropower project site caused the source of Tsheringma drubchu to dry up.
The sacred spring is believed to be the holy water of goddess Tsheringma and drinking the water is believed to make ones voice melodious. The sudden drying up of the spring has left locals confused with some even believing it to ominous.
Tangsibji gup Gyembo Dorji said that the sudden drying up of the spring could be because of the Nikachhu hydropower project being too close to the spring. He said that this incident has not only confused the locals but also the commuters who travel through the Thimphu-Trongsa highway as the spring had never gone dry in the past.
Gup Gyembo Dorji has already put up an application to the dzongdag requesting the administration to address the problem soon.
The distance between the current location of the project’s tunnel and the water source is over 350 meters and the excavation of the tunnel had crossed the drubchu area. According to project officials, the Face 6 of Head Race Tunnel (HRT) Adit III had been facing water ingression since June 20 because the tunnel was initially excavated in an area with weak pegmatite formation.
In an email interview, project officials said that work on the primary support for the tunnel was almost completed when there was a sudden ingression of a huge quantity of water inside the tunnel that forced workers to stop their work. It is estimated that the discharge of water inside the tunnel had reached up to 304-340 liters a second.
On June 20, upon investigation, the project officers and the geologist found no decrease in the volume of water in the lake above the Tsheringma drubchu and other nearby streams. However, the ingression of water in the tunnel continued and on June 26, project officials found that the water source feeding Tsheringma drubchu had completely dried up.
“According to the geologist, the water table feeding the drubchu had started depleting because of the high water ingression inside the tunnel,” the project officials said.
Deputy Managing Director of NHPP, Sujan Rai said that the water is being pumped out of the tunnel using three 25 horsepower pump and a 50 horsepower pump for the plugging of the cavity to start so that the drubchu can be revived.
An emergency meeting was also held between the project authority and the local leaders as soon as news of the spring drying up broke out. “After the meeting, we immediately ordered HDPE pipes measuring 1,500 meters with accessories from Phuentsholing and we expect the first delivery to reach the site by June 30”, Sujan Rai said.
The project authority has assured the gewog administration that the restoration of the drubchu will be their first priority and has promised that the leaking cavities would to be sealed using high-grade cement.
Former environment engineer Yeshey Penjor said that the drying up of the spring could be directly attributed to the seepage caused by disturbances due to blasting vibrations in the aquifers. He also said that an in-depth geological stability study is suggested for the project to prevent occurrence of such incidences, which keep adding costs on the project.
Efforts are on to resolve the drinking water problems by supplying water from Zalamchu stream, which is about 530m away from the drubchu.
Kinley Tshering Dendup