On May 16, 2020[i], the penstocks of the 100 MW Uhl III project at Lad Bhadol in Mandi in Himchal Pradesh, under testing, burst, leading to flooding of downstream power house. 30 people working at the project were trapped but all have been rescued to safety. The power house is about 150 m from the burst point in Chulla village.
The Project The Uhl river on which the project is built is a tributary of Beas River. The project was accorded techno economic clearance by the Central Electricity Authority on Sept 19, 2002[ii].
The project is being executed by HPSEBL-run Beas Valley Power Corporation (BVPC). The project was to be commissioned by 2009, but its completion dates has been extended four times in last eleven years, the cost has gone scandalously high to Rs 1800 Cr.
SALIENT FEATURES: Head Race Tunnel: 8459 m length X 4.15 m dia
Surge Shaft: 13m X 57 m
Penstocks: 3.4 m dia X 1860 m length
Surface Power house
Techno Economic Clearance by CEA: CEA TEC 0902
Env Clearance date: EC 15112002
Forest Clearance Date: 20.12.2002
Investment approval date: 26.09.2003
Completion Date: 2006-07
Approved Cost: Rs 431.56 Cr (Sept 2002); Rs 940.84 Cr (March 2008); Rs 1281.52 Cr
Expenditure: Rs 1259.29 Cr (by March 2016)
It may be noted here that the CEA TEC in Sept 2002 was for a 100 MW project with two units of 50 MW each. The project as it is constructed is not three units of 33.3 MW each. This change would have required fresh TEC, but it is not clear if fresh TEC was obtained or change in TEC was obtained.
The Disaster A penstock harnesses fast-running pressurised water and delivers it to the turbines for production of electricity in hydel projects. “Penstock burst when the engineers increased pressure to enhance the load to 16 MW (from 8 MW). He said that one of the engineers climbed up the hillock, where the burst took place and closed the penstock valve, preventing further damage. The damage is being assessed,” Jogindernagar Sub Divisional Magistrate Amit Mehra said[iii]. It means that the penstock was not even running at half the design load and it burst. The project has three units of 33.3 MW each.
The penstock was 1.86 km long and the incident happened near Chulla Power house[iv]. The power house has suffered damage worth Rs 20 Cr, it is estimated. The penstock testing started at 11.30 pm on May 16 with load of 8 MW. When an hour later, the load was increased to 16 MW (which was still less than half of the design load), the penstock pipe burst, flooding the power house with water and muck.
The project work was over a year back, but last one year went in addressing the leakages from the reservoir and penstock pipes. Penstock leakage was detected during hydro static pressure test. Chemicals were imported from Singapore for stopping reservoir leakage and welding was being done to stop penstock leakage. After the burst, one of the engineers risked his life to go up to close the valve to stop the flow of water into the penstock.
MP Ramswarup Verma who reached the site alleged that the rejected pipes were used in the penstock and this will be inquired into. He also asked by the MD and other senior officials were absent at the time of testing.
Disaster needs independent inquiry The government has ordered a high level inquiry and appointed a-three-member panel headed by HPSEB chairman to probe the mishap[v]. The mishap requires an independent probe, but since HPSEB chairman is heading the probe for mishap at a HPSEB joint venture project, this is clearly not an independent probe.
The UHL project has already seen multiple disasters. The project has seen MASSIVE cost and time over runs. Its penstock and reservoirs have been leaking even before the commissioning of project. And now while commissioning, the penstock has seen such unprecedented massive burst while the load was just starting at less than 50% of design load. The cost of the project is already way beyond economic viability. Who is going to buy this expensive power? Thus the project urgently needs and independent inquiry, not an in house one like the one HP govt has announced, headed by HPSEB chairman.
Incidents of pan stock failure have caused havoc in Himachal projects earlier. Such incidents have also happened in Kinnaur Sorang Power House[vi], Micro Power House Kullu.[vii] But it seems no lessons have been learnt from these earlier disasters.