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Covering storm-water drains, in my understanding, is never the right thing to do. Why people want them covered is because it's rarely storm-water, that's flowing in the drains, but raw sewage. And, that's what needs to be tackled, and on a war footing. Once that's done, nobody will want them covered any more. And, with the right kind of land-scaping, they will add charm to city, like they do in any number of European cities.

Unfortunately, the BBMP is today encouraging hoarding contractors to place the hoardings in such a way as to block the sight (not the stink, though) of the drains while crossing them over a bridge.

Muralidhar Rao

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Hello Mr. Rao,

Further to my email sent a little while back, if drains are carrying sewage, where does storm water run offs go? Do we all not pay betterment charge to BBMP to lay sewage lines underground? And is it not the constant complaint of people that the underground sewage lines are too close to water pipelines and on several occassions water from the sewage pipes have got mixed with cauvery water pipes contaminating drinking water?

The reason why open drains stink is because Bangaloreans invariably dump their daily household garbage in the open drain. Bacteria grows with the warmth of sunlight and photosynthesis takes place leading to algae and growth of other more dangerous bacteria. World over there is no open drain system. Are they all not following what is healthy?

Regards,
Chari

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Mr.Chari

Extract from home page of *:

 

.....* is a California (USA) based company (with offices in Michigan, USA and Bangalore, India) whose mission is to offer the most innovative and state of the art energy saving, resource recycling and automation products sourced from all over the world and offered to clients under one umbrella of supplies and services.

They also have a number of rain water harvesting and other solutions:

 

But in your above post to Praja, you have mentioned:

"An innovative technology is now available in Bangalore (imported from Australia) which will solve storm water drainage problem once and for all.

Excuse me if I have got it wrong because * does not have even a branch office in Australia.  This post is only to seek clarification.

By the way, in Bengaluru, we have our Zenrainman, who may be contacted.

- Vasanth Mysoremath

 

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An article that I wrote which i thought would be relevant for this discussion 

Storm-water management– The new paradigm

 

Consider an undeveloped plot of land in a city. A fairly level empty site with no construction on it yet. When it rains on this plot, depending on the intensity and volume of rainfall, this is what is most likely to happen. 10 % of it will runoff as storm-water, about 90% of it will be absorbed by the soil but only about 10% will infiltrate and percolate to become groundwater, 80 % of it will most likely come up through the soil and either evaporate or evapo-transpirate, being taken up by the roots of plants and trees and sent out into the atmosphere through the leaves.

Now consider the same site with construction on it. The situation will dramatically change. Of the rain falling on the site 90 % will run-off as storm-water, about 5 % will evaporate or evapo-transpirate and about 5 % will infiltrate and percolate into the ground. This 90 % run-off now races to low lying areas quickly, overwhelms the drainage system and causes urban flooding with disastrous consequence to life and property.

The double whammy comes from the fact that urban areas are also prone to increased rainfall in volume and intensity because of the heat island effect, where the crust of the city such as roads, pavements and buildings absorb heat and radiate it into the atmosphere causing temperatures to go up and for the rain clouds to fall more and faster.  

Solutions: A source control strategy will look at two major methods called retention and detention. Retention is to store storm-water. Since most storm water comes from individual sites, these sites can act responsibly to retain or detain the water. Retain is a more permanent affair while detention means a temporary holding of the water before its release into the drainage network.

Retention can be as simple as storing rooftop rainwater in a drum as this house on Hayes road shows. By placing a Rain Barrel of 5000 litres capacity and leading their 200 square metre rooftop rainwater to the barrel they have not only managed to ensure that a 30 mm rainfall does not go out of the house but also that they have additional water ‘straight from the sky’ for their use. Retention can also be taking the rooftop rainwater and storing it in sump tanks.

 

http://www.youtube.com/watch?v=Dz_VGaPr610&feature=channel_page

 

Detentions are slightly different affairs. Detaining waters is easily done by making recharge wells and leading the rooftop rainwater into them. They will gulp close to 6000 litres to 10,000 litres in a day and ensure that the water goes to the aquifer than to the storm water drain. Some of the water may emerge as base flows but some may completely go to make up the underground water table. Typical recharge wells in the Bangalore context are 3 feet in diameter and 20 feet deep.

Detaining structures can also be placed in the storm water drain or adjacent to it, thus picking up and recharging storm water.

With simple steps from individual homes and apartments to either store rainwater or to recharge it , it should be possible to manage urban floodings. It is my opinion that a combination of simple technologies would be better than a foreign technology which is centralized in approach

Rainwater harvesting rules help facilitates storm water management, provided they are designed and implemented with care. Cities which seek to manage water harmoniously can avoid floods and augment there water supply through these retaining and detaining structures instead of investing huge sums of money to build large storm water drains, difficult to maintain and wasting a precious resource. The choice is ours and we must make wise decisions now. 

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 While I agree companies and individuals tend to promote solutions they have, we must remember there is a ton of expertise and solutions out there that needs to be tapped into. We cant have BBMP engineers thinking they know it all. There has to be a structured way of defining the problem and opening up the solution document to various options with a benefit analysis on each one. If this is transparently managed by a neutral comittee and open to solutions from across the globe then you will get the best of breed. And we DESERVE the best of breed.

I cant believe solutions from the same set of people in the same closed room is going to give a different solution than we had for so many years. It is important for administrators and city workers to admit they are not supermen but also go out and get solutions instead of admitting and sitting back.

The key again will be to pilot some of these in select areas at the vendors cost and see if it really works. 

§§§ Tweetenator

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