Land subsidence in Joshimath not linked to NTPC tunnelling: Union govt

The construction work of 4x130MW Tapovan Vishnugad HEP was started in November 2006 by NTPC Ltd. The project included the construction of a concrete barrage at Tapovan (15km upstream of Joshimath town).

The Centre has refuted suggestions by environmentalists and some geologists that tunnelling associated with National Thermal Power Corporation’s (NTPC) 520 MW Tapovan Vishnugad Hydropower Project near Joshimath town led to an aquifer burst that may have triggered land subsidence in Joshimath.

Land subsidence in Joshimath (HT Photo/Rajeev Kala)

In a letter drafted to be sent to the Uttarakhand government, the union power ministry stated that sub-surface seepage erosion by natural drainage, occasional heavy rainfall, periodic seismic activities and increased construction activities appear to be the main causes of subsidence while stating that the NTPC tunnel is not passing under Joshimath town.

The tunnel is at a horizontal distance of around 1.1 km away from the outer boundary of Joshimath town and vertically around 1.1 km below the ground level. Construction of the tunnel in this stretch has been done through Tunnel Boring Machine (TBM) which causes no disturbance to the surrounding rock mass, the letter dated January 11, seen by Hindustan Times said.

“That linkage with NTPC hydropower project has been refuted now,” a senior environment ministry official who did not wish to be named said on Friday.

“The letter has not been sent yet. It is correct that we have drafted a letter. Still, we are sharing it first with the home ministry, and then will share it with the Uttarakhand government,” a senior official in the power ministry said, seeking anonymity. The letter though was being unofficially shared among officials and NTPC staff.

“The land subsidence in Joshimath is a very old issue,” the letter said.

The construction work of 4x130MW Tapovan Vishnugad HEP was started in November 2006 by NTPC Ltd. The project included the construction of a concrete barrage at Tapovan (15km upstream of Joshimath town).

The Head Race Tunnel (HRT) of the project is not passing under Joshimath town. The tunnel is at a horizontal distance of around 1.1 km away from the outer boundary of Joshimath town and vertically about 1.1 km below the ground level.

The letter mentioned that a committee was constituted by DM Chamoli comprising the director (National Institute of Rock Mechanics), director (IIT Roorkee), director (Wadia Institute of Himalayan Geology), and director (National Environmental Engineering Institute, Nagpur) that concluded in August 2010 that there is no ground evidence of any instability induced by HRT excavation.

The letter further states that the construction of the tunnel in this stretch was completed in August 2011. “Construction of the tunnel in rock mass at a depth of around 1 km causes no impact on the surface ground including flora and fauna. There are no signs of sinking around the tunnel alignment at the overground surface,” it states.

According to the letter, the committee found that the possible causes for the land subsidence in Joshimath town and the surrounding area include overburdened dump materials, underground saturation resulting from poor sewerage, inadequate surface run-off disposal, rainwater and household wastewater, previous flood events causing natural drainage, toe erosion along the left bank of Alaknanda river, occasional heavy precipitation, periodic seismic activities and increased construction activities.

“It’s too early to say with certainty that the NTPC project tunnelling is not linked to this subsidence. We need an investigation of data sets. At the moment we cannot completely refute the link,” said Kalachand Sain, director, Wadia Institute of Himalayan Geology (WIHG).

“We have absolutely no doubt that NTPC’s tunnelling has suddenly exacerbated land subsidence in Joshimath. The tunnelling was done earlier but restoration work in the tunnel started after the February 2021 Rishiganga deluge. In November 2021, 14 houses complained of cracks, now 678 houses have cracks. This is directly and certainly linked to restoration works in the tunnel,” said Mallika Bhanot, a member of Ganga Ahvaan.

Following the 2013 Uttarakhand flash floods in which at least 5,000 were killed, the Supreme Court on August 13, 2013, ruled that no new hydroelectric power projects should be set up in the state. Further, 69 projects were envisaged in the region at the time whereas, 24 were granted environmental clearance, which was also stayed by the apex court.

The court sought a detailed assessment of the cumulative impact of hydropower plants in the state. Following the order, a committee headed by Ravi Chopra, director of the People’s Science Institute, submitted a detailed report which warned that glacial retreat in the state, coupled with structures built for hydroelectricity generation and dams, could lead to large-scale disasters downstream.

HT reported on March 19, 2021, that the centre wished to go ahead with seven construction hydropower projects in Uttarakhand despite opposition from activists and local residents, which has resurfaced again in recent weeks following the February 7, 2021 flash flood on the Rishi Ganga.

In an interview with HT last year, Ravi Chopra, former chairman of a panel set up by the Supreme Court to oversee the widening of roads under the Char Dham Pariyojana in Uttarakhand who resigned from his post in February last year said: “In 2014 the expert body which I headed had warned against the construction of dams above the main central thrust or the paraglacial zone. If that warning were heeded, the Tapovan Vishnugad disaster in Chamoli last year could have been avoided saving 200 lives.”

“Several court orders stated in the past that no building should be built within 100 or 200 metres of river banks. Mountain districts need to change into a forest, horticulture and sustainable agriculture economy along with development of community-based tourism, not highly centralized tourism,” Chopra had said.