QUESTION
Mud in borewell water due to rain in Chennai, TN - Is this a temporary problem and can flushing the borewell be helpful

Facts: We have dug the borewell in the month of August 2009 for 260 ft. and fixed the submersible pump at 250 ft. Upto november 2009, the water was clear when the rain started. After the rain, the water became muddy.

ADDITIONAL FACTS:(In addition to the facts already provided)

1. Level of mud in water - When we start the motor, the water is very clear for a few seconds(Refer 1st Jar in the picture attached) and thereafter it turns to turbid level forever(Referred second jar in the picture attached).

2.  Casing Pipe Details: 

  • Total depth of the borewell - 260 ft
  • Width of the borewell - 5" and 4" as per the below information
  • First 20 ft from the bottom - 4" plain pipe
  • Next 80 ft above - Slotted 4" pipe
  • Next 20 ft above- 4" plain pipe
  • Next 60 ft above - slotted 4" pipe
  • Next 30 ft above - 4" plain pipe
  • From surface to a depth of 60 ft - 5" pipe(Note: This covers the initial 10 ft of the 4" pipes)
  • Note: All these pipes are ISI marked PVC pipes

3. Fixing of Submersible Pump:

  • Motor: 1 HP 12 Stage CRI submersible pump  is fixed at 250 ft.
  • Hose: 1.25" 6 KG HDPE Hose pipe - used for the total 250 ft.

4.Preventive steps taken:

  • The borewell pipe has been covered with PVC Cap leaving space for the hose..
  • A chamber has been built around the borewell upto 1 ft depth.
  • The chamber is closed with manhole cover.
  • These measures make no chance for the surface water to enter the borewell.
  • Note: No other additional steps have been taken as it is not an open borewell.

5. Location - We are located at Chennai(Ambattur) - 20 kms away from seashore.

6. The level at which water was first struck - Below 160 ft. (we are not sure about this fact)

7. Presently, the water level in our alternate open well is at a depth of 25-30 ft.

8. The distance between the bore well and the open well is around 15-20 ft.

9. Note: We have stopped digging the borewell at the depth of 260 ft as the water content was sufficient for our use.

10. The sand structure is as follows:

  • Rocky soil - After attaining a depth of approx. 150 ft.
  • Normal (Brown) soil - From the surface to a depth of 150 ft.

11. The Nature of mud in the water: Similar to sea sand. (However, the water is good in taste.)

12. Presently, we have suspended using borewell. We are using the alternate open well.

Actions taken: 1. Stopped drawing water from the borewell for few days in order for the mud to settle down.

                      2. Water was released to our gardens at a rate of 5 hours per day for a few days.

                      3. Due to the above actions, the level of mud in the water reduced, though not fully during the months of                           December, 2009 and January, 2010.

                      4. On February 15th, Lifted the pump by 25 ft. above and noticed the same level of mud in the water.

Suggestion Received: We have been suggested to flush out the borewell using compressor, to remove the after effects of rain.

Questions: 1.Is the suggestion valid?

                 2.Are there any other solutions?

                 3.Is this a temporary problem?

                 4.We have an alternate well to meet our water requirements. Hence, suggest long term as well as short term solutions.

P.S. The digging of borewell was properly supervised and there could be less chances of any defect in the bore.

by
28 February 2010