We attempted drilling a borewell under the portico of a built house using flexible rig (using compressed air with the lorry standing  outside on the road) at Ramamurthy nagar, Bangalore. The rig stand was kept under the portico. The borewell driller used the PVC casing. He said hard rock was found at 100 ft and inserted the casing upto 100 ft and drilled further for another 70ft.

Suddenly it was noticed that casing was moving up and down/ going down further slowly feet by feet. At this stage it was noticed that muddy slush started coming up, which was attributed by borewell digger due to disjoining of casing at around 60 ft and because of this, loose sand was coming into the borewell and coming out in the form of slush. At this stage, driller said it cannot be continued and drilling was a failure.  Nearby water has been found at 350 ft to 400 ft depth and the hard rock is found at 100 to 110 ft.

In this case, the drilling has been done upto 175 ft only and the disjoined PVC casing is struck inside the bore.

We want to know whether it is possible to repair/replace the struck casing and continue drilling the same point till we get water?.

The 2nd question I have is if we want to dig a new borewell near to this halfdrilled damaged borewell, what is the safe distance and what method should be adapted( slow rig or flexible compressed rig?
thanks for your reply

Lakshmi Narayana
narayana_v@hotmail.com