We dug a borewell in March, 2011 on a 50X40 vacant residential site in C.V Raman Nagar. The following data was given to us by the borewell drilling company on completion of drilling & they told us that the well was low yielding but we would still be able to pump 1500-2000 litres in 1 hour in the morning & another 1500-2000 litres for 1 hour in the evening. During the drilling, we struck rock at 84 ft & after 320 ft there was some moisture in the discharged sand all the way upto 820 ft. We drilled upto 820 ft because that was the water level depth in & around that area based on enquiries & recommended by the diviner.
Total well depth drilled - 820 ft
Water struck at depth of - 120 ft , 320 ft
Total yield - 3/4 inches
Soil condition - Boulders & Silt
Recommended to use 2HP Air Compressor pump
After 4 days , we checked the water level in the well using a video camera. We went in for the camera test because the pump test is not yet possible on the site as we don't have temporary power connection yet & we were fairly desperate to atleast see the water after spending 1.5 lacs on the well. The camera hit water at 255 ft, which means that there was (820 ft - 255 ft) = 565ft of water column inside the well. The camera report confirms fractures at 200, 260, 265, 300, 375, 392, 480, 505 & 792 ft. We could see water flowing alongside the side of the well at 120 ft & once the camera entered the water, there were bubbles & ripples in many places which the camera crew pointed out as micro water sources.
Overall the camera crew recommended that we could go for submersible pump with auto level controller as there was sufficient water. They also recommended that we install a filter pipe before installing the pump as there were multiple loose rocks inside the well.
My questions to the experts are as follows-:
(1) Given that the water level rose to 565 ft from the bottom of the well in 4 days - is the water yield actually more than the 0.75 inches that was initially stated by the drilling company ?
(2) Should we go in for the submersible pump as recommended by the camera crew or compressor pump as recommended by the drilling company ? There is only 5 ft of silt at the bottom of the well. We were able to take the camera down upto 815 ft.
(3) We drilled the well in March, which is basically after 6 months of dry weather in Bangalore. Is the yield likely to improve after the monsoon, which is July - Sept in Bangalore ?
(4) Is the yield likely to improve if we collect the rainwater from the open terrace catchment & channelize into the borewell ?
(5) Is the filter pipe a must ?
Thank you in advance for responding to my questions