TIRUCHY: Following revision, the Tamil Nadu Transmission Corporation Limited (Tantransco) last week submitted a Rs 70-crore proposal with the state government for laying an underground extra high tension (EHT) power cable line spanning a length of six kilometres aimed at ensuring uninterrupted supply to Thiruvanaikoil. If approved, the project would replace 19 high-tension (HT) towers currently standing on the Kollidam river bed, two of which collapsed during heavy water flow last year.
Electricity to the 110 kV substation in Thiruvanaikoil is currently fed from the 230 kV substations at Thatchankurichi and Tiruchy metro through the towers in the riverbed. In August 2024, two of the 19 towers were washed away after a discharge of 1.2 lakh cusecs into the Kollidam. The two towers near the Kollidam bow-string girder (Napier) bridge caved in when one of their legs gave way, resulting in both their collapse.
Following this, the Tamil Nadu Power Distribution Corporation Limited (TNPDCL) implemented a load management plan to maintain supply to Thiruvanaikoil and Srirangam, which, however, came with inconveniences to residents. The temporary arrangements remained until the installation of two new towers, replacing the collapsed ones, at a cost of Rs 3 crore in July this year.
Officials, however, pointed out that towers on the river bed remain vulnerable and could collapse again if the water flow exceeds one lakh cusecs. To address this is the proposal to shift the transmission line underground, they said. Under the proposed project, an EHT cable duct will be laid from the Thatchankurichi and Tiruchy metro substations which will run near the river bed for about six kilometres along the Tiruchy-Chennai national highway.
This will allow the power cables to be buried beneath the surface and eliminate dependence on river bed structures, officials said. Underground transmission offers significant advantages, including improved reliability, reduced visual impact, lower maintenance and enhanced safety, they added.
Mary Magdalin Princy, superintending engineer, Tantransco, Tiruchy, told TNIE that the underground line would be a “far more dependable alternative” for sustained transmission to Thiruvanaikoil. The corporation had initially submitted a proposal costing Rs 80 crore but the government asked for cost rationalisation, she said. “We have revised the project to around Rs 70 crore. Once it is sanctioned we will start work,” she added.