Hello All,
I stay in Whitefield areas, Bangalore. We dug a borewell ten days back. I hired a driller through JR borewell and showed the point myself based on convenience as there weren't much options. The driller never gave me a report. so please try to evaluate based on the information given.
PVC casing upto 23ft
MS Casing upto 85ft
Water flowed out of the borewell during drilling at a depth of 420ft. 1.5 " per driller. I asked them to continue upto 700ft as one of my engineer said that a second aquifer would make the source reliable but we didn't find any other source as far as i know.
I fixed in a 3HP single phase texmo pump at a depth of 650 ft. Intially pump was never able to pull water continuously but a pause of 5 mins kept the pump running with full capacity for 30 mins. But the water would slowly reduce in 30 mins. It pumped put approx 10000 litres for two days. The third day only air was coming out and that too only for a couple of secs. After that no action. The pump installer decided to pull out the pump and check but in vain. Ten different people gave ten different suggestion. So i decided to scan the borewell. The video camera couldn't proceed beyond 310 ft. Suprisinly we saw another water source at 250 ft with water gushing out from the wall. I would say that was approx 1 inch water gushing out. There was another guy with the camera fellow who was suggesting a jerking at that source with a 100% guarantee of increased yield but i had other concerns.
Water level is at around 260ft. The other interesting fact is that water doesn't stay in the borewell i.e. it flows through some other hole. i tried to fill it with a tanker with no success.
So my questions are -
1) what has filled upto 310ft. A reliable source(geologist) says that no silt exists in Whitefield area while the driller and all others claim that silt has filled in upto 310ft.
2) what should be my next course of action ? I hired a compressor with no success. he says that air pushed is leaking out of the hole.
3) Is it a good option to abandon the pump, ignore the source at 420 ft and depend on the one at 250ft ? Somehow block the borewell at 350 ft so that water level may rise upto 100ft, lay a new pump at 350 ft and run it at timed intervals. If so what are the methods to clean upto 350 ft and block the borewell beyond that ?
4) If it is indeed silt, how can we clean it ? If cleaned would slotted PVC pipes fix the problem ? What is the silt enters through the slots ?
All I know is we struck rock at 85ft and it was hard rock all the way.
Kindly advice on further action required to rehabilitate the well.