Posts Tagged ‘recharge’

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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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Towards a water sensitive city

April 23, 2014

 

The imagination of water in a city should not be limited to its delivery and withdrawal in pipes alone. A good water management plan would mean and include the many roles of water such as the spiritual, the cultural, the ecological and the recreational in addition to the functional..

In the hierarchy of the development of water infrastructure in a city there is first the arrival of piped water supply. Drainage and sewerage follow after some time.  The city then starts to understand and manage its surface water like lakes, rivers and canals. Attention then usually shifts to groundwater management. If all this is done  and fountains dot the landscape , where rivers and lakes become clean and spots of recreation and where all waste-water streams are managed the city starts educating its citizens especially its young ones on water and spreading water literacy. This city can be said to have become water sensitive. Singapore comes to mind as one such city. Stockholm and Oslo also manage their waters accordingly and celebrate it. Seoul is getting there or nearly there. We in India are on the painful ladder and it will take time but the vision has to stay firm. Of course in a water sensitive city all citizens will have equal access to the resource and there will be no deprivation and appropriation of the commons.

In Coimbatore through a citizen government partnership the Big Tank the Ukkadam was de-silted and made ready to receive rainwater which it has collected in plenty. In Dindigul de-silting has begun of the old tank. In Karnataka State ,  Tiptur has refurbished and improved a large tank so have the towns of Sira and Tumkur.

In Bangalore the Bangalore Development Authority has invested over Rs 110 crores in improving over 14 tanks. Of these tanks Jakkur in the Northern part of the city seems to offer a potential comprehensive role of creating a water ecosystem which fits the role of what a water body can do in a city – as they say to function as its kidney.

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The vast water spread of Jakkur Tank

The tank itself was a beautiful irrigation tank with a command area which grew paddy. As the city has caught up the role of the tank has now changed. There is a wetland on the upstream end which receives water from a waste-water treatment plant. The wetland further purifies the waste-water . The tank itself with a water spread of 53 Hectares is full and harbours lots of fish. Birds nest and a virtual array of them can be seen during the year.

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Treated Waste-water comes in to a wetland

The tank has recharged groundwater in the surrounding areas and the some of the remaining water heritage of the city – the traditional wells- are full to the brim. Boys learn to swim in one of them. Another well is used for large scale irrigation of coconut and banana plants. The tank has a place for immersion of Ganesha idols in one place. Storm-water inlets to bring in rain when it occurs have well designed silt traps to allow only water to come in and not debris and solid waste.

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Full wells – thanks to a recharged aquifer

The tank ecosystem fulfills many a function, from the ecological, to the cultural and spiritual, from the educational to that of recharge and many more.

This is truly a microcosm of what is called Integrated Urban water management in practice. Here we see the transformation of waste-water through a physical process of treatment followed by a biological process to drinking water.

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Fish feeds the city with proteins and provides livelihood to fishermen

Water in a city is much beyond what flows in pipes. If designed and managed well it can enhance and provide for the needs of nature and man in myriad forms. The Jakkur Lake should be managed well so that it becomes a living lab for our citizens to see and learn how urban waters can be managed. This experiment can then be repeated in most other tanks of the city and also in other cities. Bangalore has been a pioneer in many ways to urban water management. Can it take a lead in this one too? In that would lie water wisdom.

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The culture of the well

March 11, 2013

The culture of the well

 

The well represents a culture and an ethic that is crucial to the sustainable use of water. A well taps only the dynamic water-table, which is annually replenished. 

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                     A well at Lothal – 2600 B.C.

 

 
Water Wisdom: Drawing water from a well called for effort, and so water use was efficient and minimal

 

What is a well’s relevance in a city now? It represents a culture and an ethic which is crucial to the sustainable use of water. A well taps only the dynamic water table which is annually replenished. It gives fresh clean water if the surroundings are kept clean and the well itself maintained every year. It represents an understanding of soil and the ground which resulted in the first scientific approach to understand where to dig for it, how deep to dig, how wide to dig and how to line it. It was the meeting point for exchange of information and a daily walk or two and exercise in lifting the water. Because it called for effort, water use was efficient and minimal. You would hardly want to lift more water to waste it. This, in current parlance, is called demand management. The water from the well was free, the human right to water.

The well talks to you if you care to listen. It tells you that summer is approaching as water levels fall. You are asked to be prudent and conserve water. It tells you that this year the rainfall failed and is a drought year so there is very little water available. It also tells you about years of plenty when sometimes the well filled to the brim. Demand and supply was, therefore, based on ecological availability of rain and water and was dynamic.

Contrast this when man is distanced from the source of water with a utility as an intermediary. The borewell and the pipelines hardly converse with you and water is now distanced to be consumed as a commodity. When the resource runs out there is a feeling of betrayal and panic.

The culture had its ills. Wells were caste-based in certain areas with certain people not allowed to use it. It became polluted easily if not taken care of. Certain disease like cholera could spread easily if the water was not treated and people committed suicide in it.

Modern recharge wells

It is therefore heartening to see the revival of the well culture.

Rainwater harvesting being made mandatory has seen a proliferation of recharge wells- structures 3 to 5 feet in diameter and 10 to 30 feet deep are being dug and rooftop rainwater filtered and led into it. A recent visit to an apartment of 24 flats was enlightening. The occupants had dug seven recharge wells and made sure that every drop of water falling on the site was diverted to it. Over time the water levels had come up and could be seen in the open well itself.

The borewell, 200 feet deep, which had gone dry had revived and was yielding better than old times. Every time it rained the occupants would check that the system was functioning and that water was flowing into the recharge wells.

The connect with rain and water seemed to have been re-established for these urban dwellers.

An old well on rocky terrain which had gone dry showed 20 feet of standing water after recharge. A small pump was humming merrily and the well water was being used.

Open wells have the least energy costs in pumping and the higher the water table the lower the energy demand. Rainwater harvesting and recharge helps reduce energy demand and carbon emissions.

All over the city wells are making a comeback. Now to receive water and replenish the earth, unlike the old days when they use to give water. Wells can be planned and integrated in every form of development — individual homes, institutions, industries and large apartments. Storm water and rainwater networks can be linked for recharge of the aquifer.

Urban flooding can be reduced, if not eliminated, through the right design and use of the wells and with time and careful stewardship they shall connect the clouds and the earth.

Precautions

Two precautions are needed: adequate collection and disposal of sewage so as not to pollute the wells and adequate disposal of garbage.

Restricted demand based on availability of water in the well will mean sustainable water needs for the city.

Cities would be well advised to reinvent the well culture both from a traditional but also a functional point of view.

We can rightly say all is well with our waters then. That would be water wisdom.

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The commodity that is water

February 23, 2013

Water as a commodity

The open well close to Jakkur is a beautiful structure. It is at least 50 years old and was built in the old style of dry stone pitching. Unlike many other such wells which dotted the landscape it did not have the beautiful flight of steps sweeping in to the water level. The water was used for all domestic purpose including drinking by the farmer.Image

The city then crept in and farming was given up as an occupation. The land was rented out and the renters of the small rooms built on the land, drew water from the well using buckets and a pulley.  Times changed and now there is a water scarcity in the city. Construction works need water and are not provided for by the piped network. Apartments have sprung up and they need enormous quantities of water. The price of water is Rs 600 for a tanker load of 6000 litres.

The well has now been ‘auctioned’ for Rs 15,000 a month to a water tanker operator. The more trips he makes the more money he makes. He now extracts water using a pump and has sunk a small tube-well within the open well too. Water is now a commodity and its value is Rs 100 a kilo-litre. The original users of the water now have to struggle to bring it from far off places.

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The water in the well is being treated as a private resource whereas in truth it should be treated as a community property resource. In actuality a waste-water treatment plant funded by the state treats and releases waste-water into the Jakkur lake, which too has been redone with public monies. These public investments recharge the aquifer all around and keep the wells with water. The extraction of the water is however private and land-owners and tanker operators are making the money from this public investment.

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The key challenge for the institutions is to regulate this withdrawal of water in a sustainable fashion and to draw enough through cess and tax to keep the ecosystem running in a condition that the lake is always full and the waste-water treated.

The true cost of water is captured when it is returned to nature at no negative impact and when the ecosystem is maintained to ensure continuous supply. Policies should be framed and laws put into place so that this outcome is realized on the ground. Public monies invested should generate public goods and not private benefits.

Recognizing and seizing such opportunities , the city should set up waste-water treatment plants in or close to all lakes, build constructed wetlands around these lakes to further improve water qualities , fill up the lakes to enhance bio-diversity and then to make full use of the recharged groundwater so that the entire city benefits.

This form of commodification of water and wastewater which benefits all people in the city as well as the ecosystem is the way forward. That would be one step in water wisdom.