Fiddling with the design proved costly for the USHP-2 but renewed efforts are bringing the project back on track. A Kashmir Life report.
Almost a replica of the 105-MW Lower Jhelum as far as the capacity goes, the Upper Sindh Power Project-II (USHP-II) is the first initiative of its kind in which the engineers tapped two different water sources for feeding a plant and the two canals came from two different directions. The geology of the place¸ however, threw a spanner and created a situation that one of the three units is still not operational.
Part of the crisis, engineers believe should be attributed to the situation that emerged at a time when the execution was in fast forward mode. In 1990s, most of the contractors working on the civil and mechanical side of the project fled Kashmir. These included ACC, TRG, KCT, TSL, P&R and BHEL besides, score odd locals who were implementing various civil side jobs. At a later, stage when the project managers picked up the threads and resumed with altogether different implementing agencies, it fiddled with certain things that proved costly later – both in design and execution part. When work resumed in 1995, an engineer said, the worn out Russian machinery was in bad shape and some of it had become obsolete. Repairs and replacements were carried out after a series of negotiations with the suppliers.
Spade work on the project started in 1982. Given the two different feeding water sources, the work started at two places for headworks – on a foothill above the Kangan town to tap the Wangat nalla and at Sumbal slightly ahead of discharge from the USHP-I.
The 6.75 km Wangat canal was brining in 450 cusecs of water to the forebay. Another canal taking off from Sumbal gets 1400 cusecs from Sindh rivulet. Interestingly, the USHP-I would also drain into this canal after generating power that ensured a better supply to the second stage. The canal coming from Sumbal is 16 kms long and snakes around the same foothills in the Sindh forest range that its eldest cousin takes upstream. It has a 2-km tunnel that passes through very difficult rock strata.
As the two canals would bring in around 1850 cusecs of water from two sides, the confluence would become a forebay for the project. Interesting part of the design was that two parallel channels were set up from Wangat side permitting one to be a spill channel. From here, two penstocks of two different diameters would take off with a head of 256 meters and run three different turbines of 35 MW each to produce 105 MW power for an energy deficit place. While the major penstock will feed two machines, the other smaller one will run only one turbine.
Given the shorter distance of Wangat, the canal was ready within a few years. An open channel for most of its length, the canal was diverted into RCC conduits to run on the loose-soiled mountain edges and join the forebay. These were heavier 20-meters long square barrels of 4 meter diameter that were joined and insulated through a mix of rubber and iron. It was a structure embedded on edges. As the canal was ready, the first 35 MW unit went into generation in June 2000. For Kashmir it was celebration time.
As pressure built on the contractors executing the other canal, they rushed to finish the job. By September 2001 second unit was operational as the third went into generations in June 2002. It was a mission accomplished as all the three units were running to full capacity. Generations in 2002-03 were at 2379.862 million units and in 2003-04 it was 1986.578 million units.
But crises don’t keep a calendar. The oldest unit continued running but the second and third unit fed by the Sumbal canal developed the problem of excessive shaft vibrations after 6517 and 2461 hours of run, respectively. Both the units were immediately closed down in December 2002. Experts suggested that as the water drains in the outflow bay, limitation of space triggers backflow currents that vibrate the shaft increasingly.
Immediately the work started in 2005-06 and the tail race pool was expanded as per the suggestions made by experts from the Central Water Commission. It cost an additional Rs 2.30 crore. Chennai based Structural Engineering Research Centre was engaged as consultants for testing and checking the integrity of the civil works and on basis on their recommendations the Hi Tech Civil Engineering Services were engaged for restoration on Unit II. The unit 2 was dismantled and inspected by BHEL on May 3, 2006 for three days and then put to use.
Prior to that project’s Unit 3 was dismantled in March 2005, inspected by BHEL and its Turbine Top cover was repaired. The unit was reassembled and re-commissioned on Feb 24, 2006. Both the units are generating 1.6 million units a day.
But it was not the end of end. On September 11, 2009, the Wangat canal breached as four barrels – 80 meters – of its embedded tunnel disengaged and fell down. It drained the reservoirs and the forebay and moved the mountain on which it was mounted for many years. The power house was shut as there was no mechanism of using the functional canal discharge in isolation. Locally, it created crisis as the habitation on the foothills suffered extensive damage.
It took some time to make the project functional with a single water source. The work started in December 2009 and concluded on April 5, 2010. Since then the two units are operational with optimum capacity but the third unit fed by Wangat is closed. Right now, the BHEL workers have dismantled and dismounted the unit’s turbine and the generator for repairs.
The soil strata of the mountain edge is too loose to sustain the load of a mounted channel that can seep. After a lot of rethinking, the engineers at the PDC finally decided that part of the breached canal needs a small tunnel of 282 meters plus 70 meters conduits on the two ends to reconnect it with the forebay. First set of tenders were cancelled for technical reasons in March 2011.
New tenders were floated in October 2011 and the work was awarded. The tunnel would be over within 13 months. A local construction company Rash Builders bagged it for less than Rs 10 crore. “We have been working for more than a month,” said one of the builders’ official on the spot. “We must finish it early next year.” A day’s delay in restoration of unit costs PDC Rs 10 lakh. The project (with a design for generating 535 million units a year) was set up at Rs 425 crore but the subsequent problem the project faced has already led to losses of more than double its cost!
SERC has put its cost at Rs 449.90 crore and its tariff at Rs 0.99 per unit. The project generated 2910 lakh units in 2010-11 and 3131.93 lakh units in 2011-12.