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Borewell : A poster (Part 1)

A 2 part poster to detail out borewells

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Borewell : A poster (Part 1)

  1. 1. HOW DO I DIG A BOREWELL?* 1 A PVC or galvanised iron casing pipe is used to prevent the borehole from collapsing. Part of it would be visible above the ground. It is installed till the depth at which hard rock layer starts, and is usually 4, 6, 8, 12 or 24 inches in diameter, half inch lesser than that of the borewell. A “submersible pump” of appropriate power rating is inserted into the borehole, typically below the lowest crack from which water has jutted out into the borehole. This pump has a “delivery pipe” attached which comes up all the way up to the surface. The pump delivers the water from this pipe, which is collected by the borewell users. 1. 2. LOOK UP: measuring yield A common way to describe the yield of a new borewell is in ‘inches’ measured by the free, unrestrained flow of water from a borewell over a 90 degree ‘V’ notch. The basic principle is that the discharge is directly related to the height of the water level from the bottom of the V notch. Understanding borewell WATER qualityDeeper borewell water usually has less microbial contamination than open well water as its water has trickled down through more rock layers. It is more susceptible to geological contamination for the same reason. Therefore these waters tend to be high on TDS (total dissolved salts). Water percolates down mainly during rain, but also from other sources like lakes – a process termed recharge. This is why borewell water has to be tested regularly to ensure that it is not contaminated. In some areas, while trickling down, the water comes in contact with naturally-occurring salts like fluorides and arsenic. India has many states which are fluoride affected (e.g.: parts of Karnataka ) and many states that are affected by Arsenic (e.g. parts of Bihar, West Bengal) 1. 2. 3. 3 Borewell metering and maintenance Meter your borewell and keep a log of how much water you're pumping Ensure regular camera Inspections Recharge dry borewells and don’t rely only on borewell water by diversifying your sources and incorporating rainwater harvesting 1. 2. 3. 4 What do I do if my borewell goes dry? You could start with a camera inspection which will help you see inside the borewell. You could in the short term opt for hydrofracturing, a process that involves injecting water under high pressure into a bedrock formation via the well. This should clean and increase the size and extent of existing fractures, and connect them with nearby water bearing fractures. This is however not recommended as it can affect neighbouring borewells. However, in the longer term it’s advisable opting for groundwater recharge solutions 1. 2. 3. 5 2 borewell basics pump motor WEATHERED ZONE SOIL casing borehole WEATHERED and fractured ZONE HARD ROCK water level pump borewell rig drilling the borehole Waterflow end view h b p *Insist that your borewell digger give you a borewell log. V Notch reading in inches Approx discharge rate in lph class 1 597 low yield 2 3382 high yield 3 9329 very high yield