RAINWATER -
Bore well
Recharging.
Most of the sources of present day water requirements are BOREWELLS. It is seen that, due to the juvenile expertise the initial efforts by the public in large and the agencies has been
rapid recharging of these bore wells. Equally their has been wide publicity to such short cuts. an effort has been made to conceptualise the actual ways and means of bore well recharging.
The layout structures of the bore wells is very typical and the durability depends on the type of the earth constituents. When a bore well is drilled, the site of the drilling is invariably one inch more than the actual diameter of the bore well. In due coarse of its life the loose soil particle accumulate around the
casing pipe and support the casing from deforming as they age by. One practice is to lay the casing pipe till such of the depth, the hard rock base is available. In some cases it is laid till the end with perforations on the casing pipe.
Let us see what could happen in rapid recharging methods. When the rain water is forced to go down the bore well, it rushes down the casing pipe either from inside or out side the surface. When water flows down from outside, it picks up great velocity. As the water flows down it pulls loose tiny particles along and a
void is created. the photo bellow shows the void created at the bore wells top opening.
As the void increases, the bigger soil particles and then the large sandy particle loose hold and are then carried away. As such a large void is formed. this in due coarse will force the casing to take deformation from its actual position. Now when the casing (PVC) deforms beyond acceptable limits the bore well will have to be forcibly abandoned. If the casing pipe is MS, due to void created, the oxidation will lead to rusting and hence the casing will one day collapse down or deform.
In cases where water flows down the casing from inside, the above problem doesn’t arise. However the fact that the structure below the bottom of the casing is not known or is not recorded at the time of drilling is a cause of concern. We are very safe if there doesn’t exist the clay soil. if in case the soil layer is clay and the uninterrupted water flow which has picked up great velocity, will pull away the clay soil and forms a void, which will pull down the rock which is the main supporting base for the casing pipe. This is highly possible over a period of time. Since the Actual cases are not yet noticed it is difficult at this stage to show any live examples. However it has been seen that the bore wells collapse. this could be due to this reason as well.
In both these cases it is a cause of physical damage to the bore well. One more dangerous damage is the contamination of water
aquifer. The water pool that takes an entry into the bare well is a mix of surface ingredients which are gutka spills, cigarette buds, human excreta, chemical spillage, fertilizers in soils, pesticides in agricultural residues and such other similar harmful solvents. These are difficult to filter out even by sophisticated treatment plants. These pollutants will take an easy entry by such rapid recharging methods and will contaminate the natures pure water source. And hence looking into the negative aspects of rapid recharging, it is highly advised not to adopt such short term and easy solutions.
It is therefore suggested to adopt direct aquifer recharging methods where one is pretty sure that there is no pollution of the rain water. Here the method could be simple sand filter with water flow down to the aquifer through the HDPE pipe which opens out right on top of the aquifer, with off coarse a provision for air vents of appropriate size.
Help yourself by following good and appropriate techniques.
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