Hello,
I got a borewell drilled in my site in december 2012. My site is around 500 meters from a lake. I got the drilling done using a gas drilling machine and hit water source at 65-70 ft getting around 2 1/2 inch water. The drilling was stopped at 80 ft as pebbles were encountered. The entire 80ft was cased using 6.5" casing pipe with small perforation done using a razor.
We are constructing a house there and the sump is built just next to the borewell. I am worried about the sustainance of water since all my neighbourhood bores are not less than 250 ft - 400 ft and now they are advising me to redrill the bore by at least another 60-80 ft to sustain the water level.
My concern is
1. Can redrilling be done in an existing borewell when pebbles were encountered previously while drilling? Is there a risk of borewell collapsing?
2. Will it not affect the sump which is attached to the borewell.
3. Is it safe to carry out drilling in an under-construction site?
I have a clearance of 11 ft at the roof level. Hence, I was suggested that a tripod gas drilling machine can be used. Please advice.