Archive for November, 2012

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Managing the periphery – Water and sanitation design for Bangalore

November 25, 2012

zenrainman@gmail.com

The peripheral areas of cities are seeing an unprecedented growth and Bangalore is no exception. Land use is changing from agricultural to non-agriculture use and sites are being developed in ‘layouts’ all across. While infrastructure like roads and electricity can and will eventually reach the layouts the case of water and sanitation infrastructure is more difficult.

The Bangalore Metropolitan Regional Development Authority assisted by 11 Local Planning Authorities is the planning approval authority for over 8000 square km. of area around the city of Bangalore.

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Since no more water is likely to be pumped from the Cauvery River with the completion of the Phase IV Stage 2 it is groundwater that most of the peripheral development must depend on. Ground water is however getting increasingly overused in the surrounding semi-arid areas of the city where the rainfall is 700 mm on an average.

How can the authority make sure that the people who move in to these developments have water and sanitation in the future?  One good way to begin is to get the layout  developer do a yield test for the bore-wells dug or available on site. If this is done in summer it is likely to give a better understanding of reliable yield for the entire layout. A quality test of the bore-well waters would also establish potability or otherwise. Water treatment plants may become necessary if the water is hard or contaminated. This should be basic information with the authority as well as what potential buyers of sites or buildings should demand from the developer.

No individual bore-well should be permitted to be drilled and only common use of groundwater under metered and tariff conditions should be encouraged in the layouts.

While rainwater harvesting is insisted upon by the entire local planning authorities a more detailed implementation and design would help both the authority and the consumer. For example it should be made conditional that all homes and flats have rainwater harvesting structures to store or recharge 60 mm of rainfall .

It should also be made conditional that all storm-water falling on non private plot area is completely recharged in to the ground. The recharge structures should be site specific and should be based on infiltration and recharge data from each site. Only in case where recharge is not possible should storage and reuse be permitted. In any case each layout should be designed as a zero run off area for rainwater.

However all conditions imposed should be easily implementable, should bring tangible benefits to the occupiers, should be easy to monitor and should have clear ownership so that it is maintained in the long run and is therefore sustainable.

At the macro-level, the BMRDA would be better off generating a detailed micro-watershed map of the area under its jurisdiction. It should then be able to push for the maintenance of these tanks and other water bodies plus their inter-connectedness through adequate policy, legislative and fiscal incentives.

The BMRDA should also map the aquifers and detailed sub-aquifer maps overlapping with the micro-watershed maps should be generated so that groundwater situation is better understood and managed with the development that will take place inevitably in the megalopolis area.

Sanitation: The Karnataka State Pollution Control Board insists on a sewage treatment plant for each development in the BMRDA zone. While this is motivated with a need to prevent water pollution and to add to reuse and recycling of water, the practical aspects of what happens to these treatment plants and who maintains them should be studied. Resident Welfare Associations and Flat owner associations find it difficult to maintain these units. As units or houses are built incrementally, it is difficult for the treatment plants to become fully functional until occupancy is at least 50 % and above.

As a matter of choice individual on-plot sanitation systems like septic tanks and baffled reactors with the right design should be permitted. These have the benefits of being maintained by individual owners and also they demand much less water than piped sewerage. A dual system of grey-water disposal and back water disposal on plot should be permitted.

While on-plot sanitation systems can be maintained with as low as 70 lpcd of water, piped sewerage will demand at least 135 litres per person per day especially for self cleansing velocity requirements.

The sustainable management of water and sanitation outside the BWSSB influence zone is a challenge. The BMRDA has to think wisely and move ahead quickly so as to avert a serious water shortfall situation.

This would be water wisdom for a city.

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When the rivers go dry – and how groundwater over-abstraction killed it

November 21, 2012

On The death of rivers and the role of groundwater extraction in the killing

Water can be both good and bad, useful and dangerous. To the danger, however, a remedy has been found, learning to swim- Democritus.

The time of Democritus (460 – 370 BCE) was a happier one for waters, be they rivers or lakes or the sea. It was not the era of pollution from sewage and industries or the era of unbridled exploitation through overuse and over-extraction , especially of groundwater, posing a much greater challenge than to learn to swim to deal with dangerous waters.

Now rivers and lakes are drying up. A primary cause is the lowering of the water table in the catchment zones. As ground waters go deeper they no longer emerge as seeps and springs to feed rivers. Whatever little water is there in these water bodies now either evaporate or re- enter the ground to be further exploited.

A recent publication by the US Geological Services – USGS – titled ‘ Stream-flow Depletion by Wells—Understanding and Managing the Effects of Groundwater Pumping on Stream-flow’ examines the phenomenon.

Its conclusion is that by far the biggest influence on depleted river flows is groundwater pumping. It also clears up several misconceptions. The belief for example that the total development of a groundwater aquifer system is ‘safe’  or ‘sustainable’ up-to the average rate of recharge. A system currently followed by our planners. This, the paper argues, is wrong. The second myth that depletion stops when pumping of groundwater ceases. This too is a false belief.

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In our immediate neighbourhood many attempts have been made to revive rivers and some are still ongoing. Say for example the effort of the Cauvery Niravari Nigam to revive the river Arkavathy. While crores of rupees are being spent on chopping bushes and cleaning drains not one paisa is spent towards understanding the groundwater and surface water flow interface and to manage the groundwater in such a way that it does not render the Arkavathy a losing stream. Good intentions are simply not enough for reviving water bodies. They have to be backed by a scientific rigour and analysis and the understanding that groundwater plays the biggest role in river and lake inflows.

Groundwater determines river flows

The survival of a river or a lake cannot be the peripheral activity of many institutions it has to be the core activity of one institution. It is time we constituted a river basin institution for each one of the tributaries of the Cauvery and the Krishna and started planning and implementing appropriate groundwater management strategies to ensure that the river systems remain healthy. That would be water wisdom.

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A new role for water bodies in the city – Bangalore

November 17, 2012

A New role for tanks in the city

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Silt trap –  Storm-water drain with silt is separated from the main lake. The silt will need regular removal.

Known as the city of tanks for years Bangalore has seen large scale destruction and encroachment of its surface water bodies over the year. Public outcry, activist groups and the courts have ensured that some efforts are on to save what remains and conserve these water structures for the city.

Built primarily as irrigation structures these tanks have outlived that particular purpose as urbanization has changed land use and converted the ‘atchcuts’ or command areas, where crops used to be grown , into primarily housing but also other sites. These tanks were also not perennial; most of them would go dry during summer.  What is therefore a new role for them in a modern city?

NEW ROLE: Tanks could serve many a purpose in the modern urban context. They could be space for bio-diversity,  acting as a wetland where many birds and aquatic life could flourish. They could be a recreational space, where such activities as walking, jogging, boating and even swimming could happen. They could be micro-environment moderating space cooling with evaporation and water vapour during the hot summer months. They could hold storm water during heavy rains and act as a water buffer moderating floods. They could be percolating structures recharging the groundwater among many other roles.

The best and most appropriate as well as sustainable role for the water bodies  seems to be that of recipients of treated sewage water. The city gets over 1400 million litres per day from the Arkavathy and Cauvery rivers. Waters which are not natural on the city as rain but piped and  brought from far to quench the thirst of the city. Of this 80 % or over 1120 million litres per day will flow as waste-water or sewage as commonly known. This water will need to be treated , nutrients and pollutants removed if we have to do justice to the ecosystem. The best way to do this  is to locate decentralized and well distributed sewage treatment plants attached to all the remaining tanks of our city.

In addition to the sewage flows over 3000 million litres per day equivalent falls as rain on the city. Over half of this can be picked up in the tanks if they are designed properly to receive the waters from urban catchments.

There are many examples dotting the landscape. The tank at Lalbagh has been refurbished and receives water from the small sewage treatment plant set up upstream of it. Almost 1.5 million litres per day thus becomes perennial flow to the tank keeping it full. This recharges the groundwater and makes it available as open well water and bore-well water to slake the thirst of Lalbagh.

Nagavara tank receives treated waste-water from the Jakkur sewage treatment plant and is always full of water for recreational activities.

Jakkur tank, with a water spread of 50 Hectares, has a 10 million litres per day sewage treatment plant located upstream of the tank. The treated waste-water is let into an artificial wetland for further biological treatment before it reaches the main water body of the tank. This then recharges the groundwater around the water body and fills up the surrounding wells and bore-wells.

In the absence of a legal and institutional framework and a managed groundwater policy a bore-well has been sunk by a private person nearby and the water is being sold in tankers to the nearby residents. The city has invested hugely in both the waste-water treatment plant and the tank itself but the benefits of recharge are being taken by private bore-well owners nearby.

Bore-well near Jakkur Lake

In theory at least 10 million litres per day could be available from the groundwater surrounding the tank if recharge is maintained well and could be supplied to 100,000 people at 100 litres per day.

There is a groundwater act passed recently and a groundwater authority has been created. This board should focus on such opportunities and see how the groundwaters can be brought to augment the city supplies as a public good rather than a private good.

The road ahead: The utilization of tanks to receive treated waste-water and then to pick it up as groundwater has tremendous potential for the city. Institutions and the law should quickly move to make this possible. The water shortage of Bangalore and in fact most cities in the Deccan Plateau can be overcome and the lakes saved if such an approach is adopted. This is truly integrated water management for the city. Are we ready to be water wise?

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Durban – Clean water surf deep

November 11, 2012

Riding the waves – the Durban experience with sea water quality

zenrainman@gmail.com

Durban in South Africa with its lovely beach front running miles is a surfing paradise. It is usual to see hundreds of surfers flocking the piers that abut the beach, diving in and catching the waves from as early as five in the morning. The warm waters of the Indian Ocean which sweep around the coast makes it a high point for the city and the beaches are lovely and clean. So are the waters.

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Responsible for water supply, sanitation and for water quality is the Ethekwini Water and Sanitation Services. The company is responsible to provide water to over 400,000 connections which it does by pumping over 900 million litres per day. It also collects and treats over 500 million litres per day of sewage which it does in nearly 30 decentralized sewage treatment plants spread all across the city.

South Africa has the first constitution in the world which guaranteed water to its citizens as a right. This means that the utility company has to provide 200 litres of water every day to every family which it does by filling up a barrel provided for the purpose. Since many of the townships have no underground sewerage but pit toilets the utility also provides pit cleaning services free. The sludge is taken to a sludge treatment plant, sanitized and pelletized to be sold as fertilizer in bags. This is one of the first of its kind in the world though it is in a pilot testing mode.

But back to the beach, since Durban has more than a 100 kilometre length of beach it is important for the water quality of the best standard and for it to be communicated to the users. There is a weekly testing procedure for the water quality which is then put up on boards all over. A website http://www1.durban.gov.za/beachwater/ also indicates through simple colour markers whether the condition is excellent (green on the colour marker) to unavailable (yellow on the colour marker). Since Durban has the busiest port in the whole of Africa it is important that segregation of the port activity and the beach activity be monitored and maintained.

The beach information includes such details as to whether lifeguards are available, whether there is access for the disabled, the sport activities such as volleyball, surfing and swimming that is possible, the availability of toilets, picnic areas and parking.  Since sharks are also present in the warm waters, nets have been placed for the protection of swimmers and surfers. This information too is available on the website and on the beach itself.

It was clear from the walk along the beach that there was no sewage flowing in storm water drains and that no storm water drains were directly connected to the beach without treatment. Significant efforts were made to run a collector drain and pick up all sewage for treatment before being released to the environment. No raw sewage was reaching the sea as in many Indian cities.

A good quality beach is important for the local residents and also brings in tourists in droves. This spurs the local economy in many ways providing employment and livelihoods.

It is time we in India too focused on our seas, cleaned up our beach, took care of sewage and storm water flows and made our seas fit for our youngsters to enjoy and learn swimming, surfing, boating and many other sports. This is also water wisdom.

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