Far from the media glare and during the heat and dust of the Assembly elections, the project to replace 136 gates of the Krishnaraja Sagar (KRS) across the Cauvery and taken up in a phase-wise manner, was completed in what is a significant milestone in the history of the 91-year-old dam.
The work on replacing the final set of 25 sluice gates was completed during April, thus bringing to close an important phase of the project taken up under the Dam Rehabilitation and Improvement Project (DRIP) at a cost of ₹58.46 crore.
Funded by the World Bank and implemented by the Karnataka Water Resource Department, the project was initiated in 2019 and the work on gate replacement used to take place only during the short window of two to three months when the water level in the reservoir used to deplete during summer.
Officials said the replacement of the 136 sluice gates overshot the deadline owing to outbreak of COVID-19 and its ripple effect. In 2021, the fabrication of the gates were hampered owing to ban on supply of oxygen for industrial purpose during the peak of the pandemic.
In 2022, the authorities could work only for 17 days as the water level in the reservoir rose rapidly owing to early and intense monsoon preceded by heavy pre-monsoon showers.
Though 48 gates were ready for installation last year, only 23 gates could be installed and authorities had to wait for water level to recede below 103 ft and it happened in March 2023.
H.S. Anand, Superintending Engineer, KRS Modernisation and Medium Irrigation Project circle, Mandya, told The Hindu that out of 136 gates, 48 were above 114 ft level, 40 gates above 106 ft, and 48 gates above 103 ft. In addition, 16 gates above 80 ft were replaced under a different project in 2011 with State funding while eight surplus level sluice gates were permanently plugged in 2007. The 136 gate replacements were part of the DRIP to arrest seepage from the dam by replacing the gates and also strengthening the structure of the dam.
The authorities have also invited tenders for construction of a four-storeyed building to install a Supervisory Control and Data Acquisition system at KRS for the automatic operation of the sluice gates. The manual element will be minimised to monitoring the system while the operation of the sluice gates will be computer controlled based on water levels.
“While gate replacements have been completed, work on strengthening the dam structure is still on and is likely to take another year. The weak spots of the wall have been identified after conducting tomography of the structure which is akin to scanning a human body,” said Mr. Anand.
The underwater grouting work is currently under way and specialised equipment is being used by trained personnel who dive in the reservoir waters, carry the application mix and surface after completing the grouting work. Each team works for an hour below the surface level after which another team replaces them. Once completed the life span of the dam will also be enhanced, Mr. Anand added.
Work on the KRS, which is the lifeline to millions, was started in 1911 and it was commissioned in 1932.
