The Airport is located quite far from the city, about 30 km away. To boot, it is located in what was called a ‘dark zone’ by the Central Ground Water Board, meaning groundwater was being exploited beyond recharge potential. An airport needs water, and plenty of it. So, what did it do?
For one it requested and sourced fresh water from the city paying Rs. 66 a kilo-litre, a high price which gave the water utility supplying it some monies. This fresh water is limited to about 1.5 million litres daily. It then did a smarter thing: it bought tertiary treated waste-water (two million litres daily), paying Rs. 25 a kilo-litre. This was separately stored and used for the vast beautiful landscape springing around, a huge bio-diversity of plants and even a small wetland.
For the internal waste-water generated, it set up its own sewage treatment plant using the extended aeration system. This treated water is then reused for flushing the toilets on the airport premises as well as for the air cooling systems. The sludge generated from the sewage treatment plant is composted and reused as manure for the landscaped area.
Runways and the area surrounding them generate large quantities of storm-water when it rains. It is therefore very important that this run-off be collected and quickly disposed of and flooding avoided.
With more than 310 recharge wells located in the storm-water drain or immediately adjacent to it a large volume of the rain is recharged into the aquifer. Well designed storm-water drains then take away the rest of the rainwater to an adjacent lake which is capable of receiving this large flow of rain. Two things have happened due to these good efforts. Four large open wells, which were old existing constructions, have been rehabilitated, cleaned up and repaired. Pumps and a filter have been attached and the water quality tested. It is found that this is high quality, sweet and potable water. Thanks to the recharge efforts, the wells stay full even during summer. Up to 800,000 litres of water can be drawn from these open wells daily and in an emergency they can replace the mains water from the city. A landscape which was once a dark zone, given a holiday for high extraction from bore-wells and with enough recharging, can be revived to such an extent that open wells can have water.
From the airport buildings, rainwater is stored in large underground sump tanks of about 1.5 million litres capacity and reused after treating. Excess water from the sump tanks is then allowed to flow into storm drains and recharge the aquifer as well as flow into the adjacent lake.
The revival of the lake also means that villages and towns adjacent to the airport, such as the town of Devanahalli, can now think of sourcing groundwater from adjacent to the lake. Through waste-water treatment and reuse and rainwater harvesting, groundwater aquifers can be revived and lakes kept full. These can then be of great help to the surrounding communities. The Kempegowda International Airport at Bangalore showcases just that. This is water wisdom.
1 The sludge generated from the airport sewage treatment plant is composted and reused as manure for the landscaped area.
2 Well designed storm-water drains take away the large flow of rainwater to an adjacent lake.
Contact the writer at zenrainman@gmail.com