ISLAMABAD: The premature inauguration of the 1,410MW Tarbela Dam 4th extension hydro-power project (c) in March by the Water and Power Development Authority (Wapda) has culminated in operational losses of more than Rs25 billion over the three-month annual flood season, Wapda sources and officials at the Ministry of Water Resources said.
Apparently, acting under political pressure, Wapda inaugurated the $850 million Tarbela-IV project in March, despite warnings from the German engineering consultant, Voith, not to operate the turbine of the fourth tunnel at Tarbela Dam while its reservoir was at the dead level.
However, the Wapda went ahead and and ran the turbine for several hours during the inauguration of the project by the-then prime minister, Shahid Khaqan Abbasi. As a result, mud and slurry from the practically empty reservoir filled part of the tunnel, rendering three turbines inoperable.
The Wapda sources said that the draft tube connecting the turbine to the tail race channel is buried under tons of mud. All subsequent efforts by government agencies, including the Pakistan Navy, to remove the debris have failed and the three units of 1,410 MW capacity have been offline since July, during the annual filling of the Tarbela reservoir.
According to the sources, the power not generated resulted in lost revenue of Rs280 million a day, or Rs25.2 billion for the 90-day flood season. To date, the government is yet to order an inquiry into the Tarbela-IV debacle. However, the Ministry of Water Resources is now considering to constitute an investigation committee to ascertain responsibility, a spokesman told The News.
According to the sources, the Ministry of Water Resources was kept in the dark by Wapda and only reacted belatedly to media reports. They said the ministry had sought an explanation from Wapda on August 29 and found its response on Monday to be unsatisfactory. The ministry has again written to Wapda in an attempt to get to the bottom of the issue.
A Wapda spokesperson disputed the contention that Tarbela-IV had been prematurely inaugurated. The project was commissioned after reviewing the available hydro-logical data and the specifications recommended by the project consultants. Such major engineering projects are prone to technical teething problems and hydro-logical hiccups, which could be resolved with technical solutions, he said.
However, sources told The News that the Wapda officials had committed further errors while trying to remove the debris blocking Tarbela-IV. The mud and slurry was dumped close to the outlet gates, where it piled up. Nor did the Wapda remove the downstream coffer dam to evacuate the slurry, the sources said.
The inlet of Tunnel IV has two openings. The deeper one is meant to flush silt through the tunnel when electricity is not being generated. The other opening is located higher to ensure clean water passes through the power generation turbines.
Since the Tarbela Dam reservoir was at the dead storage level in March, the only little water available for use during the inauguration ceremony was located in the flushing inlet and full of silt. “The result is before us now -- a daily loss of Rs280 million,” the source said.
Some 110,000 cusecs of water is required for the full utilisation of the 14 older power generation units of Tarbela Dam, which have a maximum capacity of 3,300MW. For Tarbela-IV, a further 45,000 cusecs is required during the three flood months to generate 1,410MW. Since all three new units are non-functional, that water is going down the spillway without generating any power.The sources said that the scale of the repair work on Tarbela-IV was so great that the entire current flood season has been lost. Wapda would need to construct a temporary downstream coffer dam and then drain the area between the draft tube and coffer dam so that cranes and earth moving equipment could remove tons of debris and reach the embedded draft tubes. If the draft tubes are found damaged, as is apprehended, further costs would be incurred, the sources said.
By adopting the best engineering practices and undertaking heroic efforts, Wapda engineers, consultants and contractors managed to clear the gate of Unit 16 by Tuesday evening. Ongoing work on the other gates would likely take another 48 to 72 hours. This would lead to commencement of power generation from Tarbela-IV.
