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