In another three months the Selvachinthamani Tank will be a better water body as the Coimbatore Corporation in association with the Environmentalist Foundation of India is engaged in scientifically restoring the tank.
According to Arun Krishnamurthy of the Foundation, the organisation’s volunteers and the civic body engineers are engaged in the five-stage cleaning process based on the plan devised by the UNESCO IHE Institute for Water Education-trained environmentalists. Prior to deciding the five-stage process, the trained environmentalists observed that people dumped garbage and construction debris in the tank, there was inflow of sewage and that people also dumped small and large scale industry waste. The impact of such dumping was that the role the tank played in temperature regulation and groundwater stabilisation stood affected. The impact was also on human health and the environment.
The first step the environmentalists took was to remove deposited and excess silt from the tank using the scrap silting method and excess silt from the tank bund. They then used the excavated silt for strengthening the tank bund.
They then used the silt deposits to form a ‘G’ shaped geometric island in the lake so that it served as a haven for nesting birds and aquatic life forms. The reason for choosing the ‘G’ shape was to ensure that the tank’s water holding capacity was not reduced, Mr. Krishnamurthy said.
The team had also planned to dig percolation trenches to ensure effective water harvesting and draining to the core. The plan was to dig two-foot wide percolation trenches with the necessary length to feed the aquifers to ensure maximum water retention even during droughts.
The fourth step would be bed cube installation on the silt-removed portions of the tank to grow planktons for fish spawning, which he said was an innovative concept. And, the fifth was inner bund filtration – an inner bund measuring four feet in height will run along the outer bund in the wind inward area to ensure accumulation of garbage in the zone to keep the rest of the lake free from thrash.
The Corporation could easily remove this garbage as wind movement will trap the garbage to this restricted zone.
Mr. Arun said that the work was going on for the past 10 days and added that plans are afoot to fence the tank and find help to treat the water flowing into the tank and to plant trees to green the area.
