Sinking in the mud

Silt in the Satluj creates problems for the Nathpa Jhakri Hydel project

IT can churn out 35 to 36 million units of power every day. On an average day, the 1500 MW Nathpa Jhakri Hydel project does more than that, bringing much relief to the northern states. But below the waters there is trouble and it8217;s called silt.

Top engineers in the Satluj Jal Vidyut Nigam SJVN8212;a joint venture company which mans the project8212;too are smelling trouble in the muddy waters of Satluj. In less than three years after it was commissioned, the project has seen frequent and prolonged shutdowns, severely affecting power generation and resulting in a huge loss8212;roughly Rs 600 crore in just six months.

Till now, the project has generated 11,600 million units of power and earned a revenue of Rs 27,000 crore since its commissioning in October 2003. But now questions are being raised over the project8217;s faulty designing and also the choice of equipment that could have resulted in abrupt shutdowns. So how did the engineers8217; overlook the silt issue?

Inquiries till now have hidden as much as they have revealed. Says the company8217;s CMD, H.K. Sharma, 8216;8216;Only non-technical people are raising such issues. There is no problem with the design, which has been approved by highest authorities. The equipment is the best. The only problem, which wasn8217;t foreseen, is the heavy amount of silt-content.8217;8217;

Once, the monsoon sets in, the silt content is sure to raise further. As it is in the past month the project was shut down twice to flush out the sand/silt deposits from the de-silting chambers to avoid damage to the turbines and machines in the power house. This process, say engineers, is likely to be repeated.

Last year the Pareechu Lake burst and the resulting flash flood brought the entire power generation at the project to a standstill. The silt content has grown since. Against a permissible limit of 1000 ppm particles per million units, the silt content was recorded as high as 80,000 ppm. This despite the fact that the project was designed to have 525 mt long, 16.31 mt wide and 27.5 mt deep desilting chamber8212;one of the largest one in the country.

8216;8216;Since the de-silting chamber is not designed to cope-up with an abnormally high silt inflow, the only option remains to shut down the project after it exceeds the 5000 ppm mark,8217;8217; says D.P. Bhargava, the project8217;s executive director.

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He attributes the high silt content to large-scale human activity upstream, in Kinnaur district and even in China. 8216;8216;The Satluj river is known for a high silt for ages. There was an increase after the Parceehu floods but this problem exists in China also,8217;8217; says J.P .Negi, principal secretary Power.

The state government is now insisting that the SJVN put in place effective 8216;8216;safeguards8217;8217; in the projects.

8216;8216;The SJVN must learn some lessons from these lapses and take corrective steps in future projects,8217;8217; counsels state chief minister Virbhadra Singh.