Posts Tagged ‘aquifer’

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Airports and water

June 3, 2014

The Airport is located quite far from the city, about 30 kilometres away. It is too far away from city lines and has to depend on groundwater. It needs 9 million litres per day eventually though for now 5 million litres per day will do.  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 and a full 2 million litres of it daily and it paid Rs 25 a kilo-litre for this treated waste-water. 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 extended aeration system. This treated water is then reused for flushing the toilets in 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. 

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       An internal waste-water treatment plants treats all waste-water as well as waste from aeroplanes

Runways and the area surrounding it generate large quantities of storm water when it rains. It is therefore very important that this run-off be collected and quickly disposed off 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 very high quality, sweet 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.

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                                      Recharge of rainwater has helped aquifers rejuvenate with fresh clean 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 adjacent 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 to fulfill the towns water requirements.

 

 

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                         Sludge drying beds 

Economic activity and service activity like airports are essential for economic growth and to spur the progress of a city. Instead of seeing it as placing demand on water services through innovative design they can absorb waste-water from cities and be able to use it to meet its requirements. Through waste-water treatment and reuse and through rainwater harvesting groundwater aquifers can be revived and lakes kept full. These can then be of great help to surrounding communities. The Kempegowda International Airport at Bangalore showcases just that. This is water wisdom.

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Monsoon preparations- Recharge wells – managing aquifer recharge

May 31, 2013

Many parts of the city of Bangalore have lateritic soil and highly weathered rock. By designing storm=water drains correctly and placing recharge wells such as this one, rainwater can be allowed to infiltrate and recharge the aquifer. This recharge well built in June 2004 will be completing 9 years shortly. On an average it has been sending in 1 million litres of rainwater into the ground each year. More such appropriately designed recharge wells will help improve groundwater levels , of course when balanced with managed and controlled withdrawal.

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The culture of the open well – a need for revival

January 14, 2013

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Water wise

August 30, 2008

WATER WISE

It’s the lifeline

S. VISWANATH

Think of any new development coming up in a city and the first consideration would be the source of water. Isn’t it difficult to imagine that till the 1960s the borewell as a technology did not exist in India?

— Photo: K. Pichumani

Play it safe: Continuously monitor the quality of borewell water.

It is difficult to imagine that till the 1960s, the borewell as a technology did not exist in India; that it required persuasion to get decision makers and farmers to appreciate the fact that lots of water could come up through a four-and-a-half-inch diameter pipe which went deep into the ground.

Now, India survives because of this pipe which became a six-inch pipe and now is also a eight-inch pipe. First, the pipe went 80 feet down; now it goes 1,500 feet in some places and provides for Karnataka survival water for upwards of 45,000 habitations. And almost all cities depend to varying degrees on groundwater.

Think of any building coming up in a city and the first consideration of the owner or the developer would be a source of water for the development of the site. Usually, the question is where should I dig a borewell and how do I go about it. A dowser is usually more popular than a hydro-geologist.

Ignorance

People’s faith in faith is more than in science, but if you get a ‘2-in-1’, a hydro-geologist who also wields a pendulum or a fork, the better. This is the abysmal state of the science of groundwater in our country and the complete ignorance that we display towards understanding it scientifically.

Large-scale utility providers of water such as the Bangalore Water Supply and Sewerage Board do not have a single hydro-geologist working for them. Universities and colleges do not have quality training programme and there is virtually no skill upgradation centre.

So, what is the advice to a borewell digger? Get hold of a good hydro-geologist and get him to do a detailed analysis of your site. He should be able to give you a good soil and lithological profile. Keep that map. He should also be able to suggest potential points of drilling and the depth at which water will likely become available. Approximate depths of casing required and how to go about selecting the right pump should also come from him.

Do not forget to get suggestions on recharge points and some tips on maintaining your borewell.

When you drill the borewell finally, keep the records carefully. Even failed borewells have tremendous information, so keep the knowledge on these points carefully mapped on a plan.

Monitor

Continuously monitor the quality of your borewell water and measure the summer and the rainy season discharge quantities. Develop a maintenance system for all the appurtenances such as the pump and the electrical systems. An annual cleaning of the borewells is also recommended. Fix a water meter and a separate electric meter for your borewell. This will give valuable information.

Understanding the role of groundwater, taking care of the aquifer quantity and quality and developing the science behind groundwater will be crucial to the sustainable availability of water. Each one of us has a role to play if we have a borewell. In this science lies water wisdom.

www.rainwaterclub.org

e-mail- zenrainman@gmail.com

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Observing water in nature

January 24, 2008

WATER WISE

Observation – The key to good water sensitive design

S.Vishwanath
http://www.rainwaterclub.org

As large sites are taken up for development designing sustainable water systems becomes both an art and a science. While at the individual household level water management is relatively simple, involving such elements as installing water conserving devices , designing for water harvesting, arranging for water efficient gardens, ensuring recharge of ground water, reusing grey water and possibly recycling sewage water things are a bit more complex at layout levels or at development levels averaging over an acre.
Scale: The scale of the solution can be at individual household level, at the community level and at the city scale. The term community encompasses streets or wards, neighbourhoods or even gated communities of flats and apartments. Generally the principle of subsidiarity prevails, try to find the solution at the lowest possible level of ownership. Escalate the solution only if it is inevitable.
Community level actions for water have been numerous and are worth emulating. In a small town close to Bangalore a community of volunteers got together to clean an old ,large open well. This well had become a dumping ground for garbage and water seeping through this garbage was further contaminating the ground water. Citizens came together slowly and gradually, working on Sundays and cleaned up the well. The process has moved on to other such open wells and these citizens are now engaging with the authorities to ensure the revival of as many such water bodies as possible. It was the observation power of one concerned citizen that lead to a town wide movement to engage with open wells.
In Chennai citizen groups have come together to revive many temple tanks aided by organizations such as the Rotary and several Civil society groups. In Jaipur a multi-national corporation has come forward to help restore an old ‘Bawdi’ – a step well dating centuries. All these examples are of individuals or groups thinking beyond self for taking action.

Within the boundary: At a very large scale development in Mysore, a project is under development and expansion for a software company. It is a residential campus covering more than 200 acres of land. A typical design for a water system would have looked at the piped water option coming to the campus and designed the water supply around it. To cater to the pollution control norms a sewage recycling system would have been set up and the treated water used for landscaping purpose. At times when the piped water failed to arrive, private water tankers would have brought in the emergency water requirement.
A walk around the campus with an eye for water however revealed the presence of a spring on site. For those with a internet connection http://youtube.com/watch?v=3_qmbgiUkIQ will give a flavour of how a spring looks.

Conversations with the locals revealed that this was perennial. An old well with water indicated a good shallow aquifer. A pump test confirmed a reliable and reasonable yield. It was clear that a discharge zone existed on site and that the recharge area needed to be clearly identified and steps taken to enhance recharge.

Observation, walking around, talking and looking out for the right things helped take appropriate water harvesting and water management decisions. Three wells were dug and over 200 kilo litres of water are available through them daily. Recharge structures are being designed to enhance shallow aquifer content and keep them full. The spring is a good and reliable indicator of the water in the shallow aquifer as well as base flows.

At a city scale: Understanding the water cycle from source to sink for a city is crucial. How many know what is happening in the catchment of source rivers which provide water to a town? What will be the impact of climate change? It would be therefore important to look at the water features around a town and enhance their storage and recharge capacity. It would also do good to be observational and feed in to the system the management of all surface water bodies and ground water structures such as wells.

The management of water on a large site is not merely engineering in solution but also involves hydro-geology and an understanding of the land and its characteristics. With multiple sourcing of water a reality in present times, a holistic learning around water and its management needs to evolve. This involves a cultural, ecological, hydro-geological and technical approach. Only when we bring in all these sensibilities will sustainable water management become a reality. This is water wisdom.

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