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Improvement in bore well yield and pumping method

Dear All,

I have drilled a bore well on my six acre plot about 5 kms. from Birur town, Chikmagalore district, Karnataka, during 2007 to take up horticulture. The bore well location was identified by a geologist using electrical resistivity test. He predicted the water bearing zones at the depth of 70, 210 and 300 feet and suggested to drill upto 350 feet and predicted about 2" water yield and told me it is reliable source as it will not decline during summer. His predictions were accurate regarding the water zones, we got wet soil at 75 feet, struck water at 220 feet and water quantity improved at 300 feet, even though we continued drilling till 450 feet there was no improvement in the yield. The pvc casing pipe of 60 feet fitted, below that we got hard strata (black stone chips and white stone powder came out) the driller estimated the yield as 2.0" (eye estimation without any V notch) and suggested to use a 6 hp, 12 stage submersible pump(three phase) at a depth of 310 feet. I followed drillers suggestions and installed the pump. The pump delivers full flow in a 2" delivery pipe for initial 14 minutes, and later gives alternative supply of 1 minute 3/4th of the pipe (2" pipe) and 1 minute 1/4th of the pipe.

The water yield is same during summer and monsoon, and unchanged during 4 years of operation. 

Since water yield is low I have drilled one more bore of 350 feet depth after two years, about 100 feet from the first bore with similer yield at same depths and same geological charecters. But surprisingly this borewell has not altered the yield of the first borewell.

My question is

1) What is the yield in liters/hour?

2) Is my pump selection wrong? If so, 

a) What is the ideal pump configuration (hp, stages, depth of installation)

b) Is there any possibility of using single phase submersible pump or compressor pump, as we get only 4 hours of 3 phase and about 18 hours of single phase power supply in a day?

3) Any suggestions for improving the yield of water by hydrofracturing, rainwater recharging in the same bore?

Thanks in advance

Regards

Renukaprasad

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2. Improvement in bore well yield and pumping method

Dear Sir,

Thank you for your references, I have gone through them all, and understood that a draw down test will indicate the water yield of my bore and suitable pump. On the out set it looks my bore well yield is low and I am using a bigger pump. I will do the draw down test to prevent wastage of energy and trouble of frequent motor burnouts.

Actually my major interest was in other questions. Sorry I could not frame my questions properly to highlite the priority.

Here we go again,

I have a plot of 6 acres, near Birur, Chikmagalur district. Planned for Horticulture (Arecanut, Coconut and Mango). Since I didnot get the required quantity of water in two bores I have covered only 3 acres and just managing with difficulty. The  three phase power is available only for 4 hours which is compounding my difficulty.I learnt that Air lift pumps are best suited for low yield wells with an added advantage of being run by single phase power (we get longer hours of single phase power),but there are comments like they are inefficient.

I have two bore wells 100 feet apart, running since about 4 years.  The bore wells are 6" dia, one is  450 feet deep, and other 350 feet deep, both have 60 feet PVC casing pipe , got small quantity of water at 70 feet , major water at 210 feet and some quantity at 300 feet, both yielding about 1.25" (my guess) of water. The water is very hard. There is no perceptable difference in Quality and Quantity of water between summer and mansoon months (predicted by the Geologist while selecting the location for borewells). The tube wells in the surrounding area have similer yield and quality of water but only one open well about 500 meters away has soft water. There is a big water tank about 1 km away retaining water throught the year but does not have any effect on the borewells. I want to retain the yield and if possible improve it by artificial recharging by filtered surface runoff(flood water drain canals run 3 sides of my plot).

My questions are

1) Single phase submersible pump V/S single phase air lift pump. When I enquired the pump dealer told that single phase submersible pumps cannot  run for longer hours. Is it true?

2)The lack of response by bore wells for mansoon rains indicate what ? Will the artificial recharge by recharge pit or recharge well near the bore wells help in quality and quantity improvement? any oyher method of recharge is recommended? or wether  I should go for storage of water in plastic lined farm pond for an assured supply.

3) How about hydrofracturing for yield improvement.   

 Please advise.

Regards

Renukaprasad

1. more information

1. Yield of a borewell can be assessed on the basis of an yield/step test. The method, information related to the same can be accessed here: 

http://indiawaterportal.org/ask/5548
http://indiawaterportal.org/ask/5304
http://indiawaterportal.org/ask/5421

http://www.indiawaterportal.org/ask/10000
http://www.indiawaterportal.org/ask/16477
http://www.indiawaterportal.org/ask/5603

2. Primarily some background information on pump selection can be had here:  

http://indiawaterportal.org/ask/5357
http://indiawaterportal.org/ask/5548
http://indiawaterportal.org/ask/5585
http://indiawaterportal.org/ask/5218
http://indiawaterportal.org/ask/5603

An useful external site:  http://www.ajdesigner.com/phppump/pump_equations_water_horse_power.php

Kindly do understand that the ideal pump can be selected with the help of a local pump technician who will also be able to provide in-field service. The yield that is required will have to be decided based on the estimated use. This would apply to the pump selection also.

Do go through the information provided and write back in the comments section if any further clarifications are needed.

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