for a well drill guy When you start drilling the first 20 ft or so of well do you put an oversize casing down and continue drilling thru it?? And then when you are done pour the bentonite between the permanent casing and the oversize casing and then remove the oversize casing???

I am trying to come up with a novel water system for use by me at my historical association. I have a pretty nice Hydraulic Ram (water ram) exhibit (demonstration) and have tried to rig up a way to allow the ram to pump into an airtight tank and to operate a blow off valve when the pressure reaches some moderate value, say 20 psi. The blow off valve would then close at a suitable lower pressure, say 10 psi. This would allow visitors to see a ram operating under practical conditions I recently tried a 20 lb. Freon tank with 3/4 in.bottom fill and a float system. The tank and float system were made in such a way that everything was airtight. I didn't have a pressure gauge so only volume (float level) was monitored. The float (a ping pong ball) lifted a small magnet that rose about 5 inches within a well sealed clear tube. The magnet closed small reed switches taped to the outside of the tube. I don't know why, but this didn't work out well. Maybe air was being dissolved into the water faster than I imagined. The fill cycle took several minutes and was repeated several seconds later. I think that a bladder tank could be the answer. As mentioned above, I would give up on the float idea and pipe the ram to the wet side and monitor pressure on the dry side. .I will be using a Mercoid pressure switch which will be set to these stated pressures. I imagine that I should plan on prefilling the dry side to say 10 psi and setting the Mercoid to operate the dump valve at 20+ 10 psi and release the valve at 10+ 10 psi. Sure hope that all of the words didn't turn anyone off, but I think I covered the whole situation. I would appreciate all comments. Thanks, George