MORE RECHARGE WELLS NEEDED
Don’t close old open wells, borewells, says hydrogeologist
Oppili.P@timesgroup.com 03.06.2019
Chennai:
Don’t fill in your old open wells and borewells that have run dry is the advice a hydrogeologist has for people in the city. A spell of rain is all it takes to recharge the city’s shallow aquifer, which is what these wells tap into.
Water consultant J Saravanan says that in many parts of the city, old open wells have gone dry as have borewells with a depth of up to 100ft after the last monsoon failed. He also blames it on poor maintenance and improper implementation of rainwater harvesting. One solution was to dig more recharge wells to trap rainwater. These wells should be 3 to 4 feet across and 10 to 15 feet deep. They should be kept empty, covered with a cement lid that has holes to allow the water to flow in.
Another point to remember is that the pipes in the bore wells should be slotted (they must have openings) for the first 100 feet so that water from the shallow aquifer can percolate into them after the rains.
Citing the example of Nungambakkam, Saravanan said in this area the soil was alluvial for the first 90 feet. Below that deeper aquifers were located in rocky patches. In this area people were drilling up to 300ft to tap water from the deeper aquifers. While sinking the pipes, they used plain casing in the first 100ft, which was a mistake.
Similarly, places south of Alandur are a hard rock region. The borewells companies provide plain casing from 0ft to 40ft. Whereas, the plain casing has to be given for the first 20ft and the remaining 20ft slotted casing has to be done. Only then the water from the shallow aquifer can be tapped, Saravanan added.
Don’t close old open wells, borewells, says hydrogeologist
Oppili.P@timesgroup.com 03.06.2019
Chennai:
Don’t fill in your old open wells and borewells that have run dry is the advice a hydrogeologist has for people in the city. A spell of rain is all it takes to recharge the city’s shallow aquifer, which is what these wells tap into.
Water consultant J Saravanan says that in many parts of the city, old open wells have gone dry as have borewells with a depth of up to 100ft after the last monsoon failed. He also blames it on poor maintenance and improper implementation of rainwater harvesting. One solution was to dig more recharge wells to trap rainwater. These wells should be 3 to 4 feet across and 10 to 15 feet deep. They should be kept empty, covered with a cement lid that has holes to allow the water to flow in.
Another point to remember is that the pipes in the bore wells should be slotted (they must have openings) for the first 100 feet so that water from the shallow aquifer can percolate into them after the rains.
Citing the example of Nungambakkam, Saravanan said in this area the soil was alluvial for the first 90 feet. Below that deeper aquifers were located in rocky patches. In this area people were drilling up to 300ft to tap water from the deeper aquifers. While sinking the pipes, they used plain casing in the first 100ft, which was a mistake.
Similarly, places south of Alandur are a hard rock region. The borewells companies provide plain casing from 0ft to 40ft. Whereas, the plain casing has to be given for the first 20ft and the remaining 20ft slotted casing has to be done. Only then the water from the shallow aquifer can be tapped, Saravanan added.
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