Sir,
Two months back I dug a bore well in our house and found a little trace of water at 160 feet. Stone was struck at 20 feet from ground level. However, I dug up to 290 feet, but got only stone powder. After casing, I left it unused for two months. Now we installed a 1 hp submersible pump at 260 feet depth but we are getting water only for 30 minutes. After waiting for 3 to 4 hours, we get another 30 minutes of water. But the water is found to contain small grains of sand in it, although a very minute quantity.
Today, in order to finalise the installation, we dug about a foot deep around the casing to fix it with concrete and found a deep hole in a half circle on one side of the casing. The depth of it may be more than 20 feet and water was visible deep down there. However, we filled it with sand and covered with concrete.
My question is, is the hole due to collapsing of soil through the casing gap, or is it normal?
I'm from Jeypore, Odisha, a very backward area. We have no proper equipment to see what is happening inside the bore. It is a 4.5 inch diameter bore with 6 inch casing.
Please advise what action I should take to prevent collapse of the bore through the casing. And also how to confirm if the casing is properly fixed.
Thank you