The (B) RAIN DRAIN – Making an (g)utter mistake in the name of saving rain water! God save Chennai!

The Chennai Corporation has gone ahead with a mammoth scale of constructing what is called as “Storm Water Drainage” promising that no areas will be inundated with water in the forthcoming rains. Source news: The New Indian Express

The corporation had taken up storm water drain works in 767 km worth Rs 3,220 crore in the northern parts of the city under the Kosasthalaiyar basin, and 560 km worth Rs 1,760 crore in the southern parts of the city under the Kovalam basin, which means the fund deficit Tamilnadu Government will be bleeding and washing off 4,980 crore, which is almost 5000 Crores of money into drain! Not only it is an ecological imbalance, wastage of money in making cement gutters I would call, and also has a huge impact on carbon emission.

Doing a quick maths, the CO 2 produced for the manufacture of structural concrete (using ~14% cement) is estimated at 410 kg/m3 (~180 kg/tonne @ density of 2.3 g/cm3) (reduced to 290 kg/m3 with 30% fly ash replacement of cement).

A mammoth 27, 20, 35,000 tonnes of carbon emission will be happening in building these concrete gutters. Instead of water percolating down to the ground and reaching out to the roots which extend themselves to strengthen the ground, these (b)rain drain holes are death knell not saving water, rather shaving of water from the earth and quickly rushing it off towards the sea.

The one you see on the left hand side is what I foresee an easier and environmental friendly method. The roots which penetrate into the pits while digging, or the trillions of microbes which work beneath,, for soil fixing and the strengthening of the geo-soil all would be intact, except for the filling of the dug pit with gravels of various sizes as shown in the image. This would fill the gaps, filter the water and the final filtered water would get absorbed by the ground soil thereby enriching the soil and also allowing water to re-charge the ground, thereby superficially surface water will increase and the ones which percolate down will recharge the ground water as well. Such trenches also make the roads always cleaner, as the soil at sides would always allow water to percolate and go down.

On the contrary the cement trap built now and on-going cemetery or grave for water, I would say, will plug the percolation of water for ever and only accumulate all water in a rush and gush all of the volumes of water to get drained faster and quicker to the sea without allowing even a drop of water to percolate. Also soil and leaves rush quickly to close these inlets to the so called drains, and these get choked immediately, thereby making water stagnate and stand on the road, as if in a cement tank and they never drain as quickly as seen in a tar road naturally having its sides with earthen patch!

I also see that in many areas, the sewage pipes, the electrical lines, phone lines are criss- crossing throughout the newly formed cement gutter and that would any time rupture due to earthen or watery pressure during heavy rains and may create another havoc of STP water mixing with rain drain water ( I do not like to use the word storm water drainage. How can normal rain be called as storm? If we do not know how to collect and recycle water, can we just say it is “storm water’? It’s plain rain water!

Shri. ?Ramkumar, Chennai, an ex-Indian Oil Director has developed these type of natural trenches filled with gravel along his housing society and in many Indian Oil offices and was able to save the buildings from stagnation and also stop buying tankers during summer, as he made them harvest all the water and store. Similarly Shri. Upendra Raval, from Surat, a veteran of 50 years plus in water and STP management, strongly advocates “the nature’s way of doing things, by having artificial ponds dug, gravels to fill and most importantly not damage the ecosystem around the water bodies or water ways.

He condemned the cementing of all the banks across the Sardar Sarovar project in Gujarat, saying the eco-system and cycle of microbes, flora and fauna living in tandem and in helping each other in the bio-synthesis and balancing has been badly lost, by doing so. The water gushes fast towards the sea and does not percolate into the sides through the muddy banks, those were once in existence. So there is a huge deluge of habitation, flora and fauna as well becoming redundant immediately, except for the water to be stored in large volumes only to rush towards the sea, faster than ever. He calls them as mega sized cement tanks. That’s it.

Coming back to Chennai, I do not see any smartness in this plan, and I do not think Chennai will never go up in the ladder of smart cities for their totally unscientific ways of handling water, be it rainwater or the floods or the STPs.

God save Chennai.