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Submersible pump draws muddy water

Dear Experts, We have a borewell in our house at Akshaynagar, Ramamurthynagar, Bangalore. The depth is about 320-340 feet. Rock was hit at around 120ft and the casing is done upto 140 feet. The submersible pump is fixed at 220ft. We have been using the borwell for a month. The water from borewell is muddy. In & around our house, the water from borewells is clear. Please let me the possible reasons for getting muddy water & what could be the solution?

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1.       Dear Vijay,   The


 


 


 



Dear Vijay,


 


The reasons for muddy water out flow may be due to the following:


 



  1. Loose fitting of casing pipe.  The seepage water from the top loose formation while trickling down will carry the colloidal clay particle and enter into the bore well between the gap of seating and pipe end.  The trickling would be a flow if you have met with the good water yielding zone in the loose weathered part. This will over the none pumping period will fill the bore along with the source water from the other zone. If the static water level stands above the casing bottom then the flow will be less.

 



  1. You might have got a sheared and fractured zone as your yielding zone for the bore well at any depth.  The crushed and powdered sheared zone will dissolve the loose clay like soil when the ground water enter into bore well and this powdered particle will come out as mud while you pump out the water.

 



  1. If you use a pump higher than the capacity of the yielding rate or close to the yielding rate of the bore well, then pump will suck more water from the storage zone that is below 220 feet depth.  Due high upward sucking rate, the mud settled at the bottom of the bore well will come out at the end of each cycle when the water level comes close to your pump.  Normally some mud flow occurs during early minutes immediately after the start of the pump and seizes, when the contribution from the aquifer starts.

  2. If you have obtained a soft weathered zone after the hard rock zone of about 280 feet and if the water yield zone falls in the soft weathered zone at the bottom then also there is possibility of the inherent clay colloidal entering into the bore well exist, The geohydrology of your area would most probably might have been situated in this kind of terrain. If it is in such a zone then, please note the solution is constructing a tube well with tiny pebbles and slots. 

 


If you have a observed while drilling the bore well and if you give me formation details such as time log of drilling, water yield zone and yield details, pump details etc then, we can find out the most possible reasons for mud flow and give some suggestion.


 


But at this stage any suggestion may be a futile exercise. However, you can discuss with the drilling company and ask them to clean and flush the bore well again and tighten the casing placement. 


Alternatively construct one more tank and use combination of filters and slow sand filtration to get clear water if you cannot avoid mud flow pumping.  


 


With best wishes,


 


A.    Raja Mohamed


Geophysicist


Coastal Energy private Limited


Chennai. 600 006



 



 

2. Dear Vijay,   There might be

Dear Vijay,


 


There might be two reasons for the pump drawing muddy water in your case.


 



  1. Soil slipping from the sides of the casing pipe. This happens when the casing pipe is not installed properly. Since you say that rock was struck at 120 feet and casing pipe was put up to 140 feet, the depth of the pipe is ok but the casing pipe may not have been sealed properly on the sides, which will allow passage of soil in to the bore from the sides of the casing pipe. So proper sealing around casing pipe is required.

  2. Collapsible layer: Another reason might be that there is a collapsible layer after 140 feet, which is dropping into the bore making the water muddy.

 


The remedy for this case is tedious and costly. You will have to install another sleeve of casing inside the existing one, but proper care is to be maintained to have perforations in the water bearing zones. The annular space between the older casing and the new sleeve is to be filled up with sorted coarse sand of 5 mm grain size.


 


With regards,


 


Sudhindra Mohan Sharma


Hydro-Geologist


S.S. Exploration Enterprises


Indore


Madhya Pradesh

3. Submersible pump draws muddy water

Dear Vijay,

The muddy water must be entering into your bore well from surface or shallow depth through the annular space between the casing pipe and the surrounding geological formation.

The information provided at http://www.conservationcorps.nf.ca/wellaware/annular-seal.php should help you to set right the problem.

Good luck,

Dr. R. Jagadiswara Rao 

Professor of Geology Retired

Sri Venkateswara University

Tirupati, AP 517502

rjagadiswara@gmail.com

 

 

 

Dr. R. Jagadiswara Rao, Professor of Geology Retired, Sri Venkateswara University, Tirupati, AP 517502, India rjagadiswara@gmail.com

4. Dear Vijay, I find that you

Dear Vijay,

 

I find that you has fixed your’s submersible pump at a depth of 220ft where I am guessing that there is no casing. (Casing has been done only upto 140 ft). As there is no casing I suspect that mud is coming with the water.

 

I would suggest you to read the FAQs on bore wells which are now available on http://www.indiawaterportal.org/ask/5816 as it give a wealth of infromation on bore wells.

 

I also recommend you to get your well investigated by the company that specialises in such work as they will give a solution to the problem. I also have met such a company which can investigate bore well problems and solve them. Their details are:

Contact Person:

Mr.Shankar Pradhan (99001 63113)

M/s Waterman Systems, 2/2, IInd Floor

Ashoka Building, Opp.Lalbagh Main Gate

Bangalore-560004

 

Regards

 

S.S.Ranganathan

Advisor             

Ion Exchange

Bangalore

5. Dear Vijay, The reason for

Dear Vijay,

 

The reason for muddy water during pumping is due to following reasons:

  1. The borewell constructed has not been properly developed by the concerned driller.
  2. It is advisable that the well is developed by high capacity compressor and subsequently low capacity pump needs to be lowered.
  3. Other option is to change the location of pump lowered, and low capacity pump.

 Such actions would ensure muddy free water from the existing bore well.

 

With regards,

 

D. Chakraborty

Scientist

Central Ground Water Authority (CGWA)

New Delhi

6. Dear Vijay, There could be

Dear Vijay,

 

There could be several reasons for the muddy water from the well such as:

  • Improper fixing of strainer through which the water is drawn from the aquifer.
  • Fixing a higher rate pump than sustainable by the aquifer for quick drawl of water whereby it could be sucking mud.

The solution will be to check both the above issues and take corrective action by re-fixing/changing the strainer in the first place. If that does not improve the situation study the data from the pumping test done in neighborhood and accordingly reduce the capacity of the submersible pump.

 

With regards,

 

Vijay Kumar

Hydrologist

Head-Water Resources/Senior Consultant-Water Resources

DHI-Water and Environment

7. Muddy water from borewell

Dear Vijay,

The appearence  of muddy water  is not a good sign. There is some collapsing taking place in the well. There is a possibility that the depth of the well would have already got reduced due to siltation. The question is which is the portion that is caving in. Remove the pump check the depth of the well. If the well depth is near to the original depth then change the pump placement position  and move it up as much as possible depending on the pumping water level. In case the well is showing signs of siltation then a new well need to be drilled as cleaning might not be a permanent solution.

 

Best of Luck

K.A.S.Mani 

 

 

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