We had a new water well drilled because the old well produced red water that eventually cleared but still had plenty of iron content. the old well was at 65-70 ft...it was an old iron casing.
new well drilled initially with 8' steel casing until they hit the red water seam at around 55 feet and then a 6 inch casing was inserted and drilled past the red water and then the 8 inch was sealed w bettonite pellets. (one 50lb bucket). the drillers waited approx 2 hours and started drilling the 6 inch again found water after 10 more feet and set the casing there. After a few minutes, the water turned red. They speculated that the bettonite hadnt sealed off and the original red seam was leaking into the 6 inch casing...
We decided to try and pull the 6 inch casing back out of the hole, clean the 8 inch hole out and start again with 6 inch casing.
The drillers were able to do that, incurring the additional costs of unwelding the pipe and taking it back to the pipe seller, who cleaned up the edges.
the casing was dropped into the 8inch again and dropped until back to that bed rock at approx 90 feet. the 8 inch was again sealed off, with one bettonite bucket. The manufacturer recommended waiting at least 24 hours for curing and another guy in the business recommended 3 buckets down the hole.
only one bucket was used again...
so they had 6 inch casing to 90 feet and found water at 120, but I was told it was only 1gpm, so they drilled further.
next day I was told they had good water, but they decided to drop a "gravel pack" to filter the water. I was told I had a lot of water, "there is 80 feet of water in the well" and it was pumping 11 gpm.
i was also told the gravel pack took up 40 feet of the hole so the bottom was now at 120ft.
All good, right?
Well then I got the bill... and I was charged for 55ft of 8 inch drilling, and 160 feet of 6 inch drilling. At $30/ft for both...I have two questions.
1. is it normal to drill 70 feet beyond where the casing is set?
2. I dont think I should be charged for 160 feet of 6inch drilling because it seems to me that the 6 inch drilling started at the end of the 8 inch casing at 55 feet and continued to an alleged 160 feet, which by my math is 105 feet of 6 inch drilling...
Am I off the mark?
Thanks in advance
It sounds like you are describing a drilled well. An 8” bit is used first to drill down to bed rock. The water comes from cracks in the rock and not from the soil above the rock. The 8” hole is drilled down into the rock deep enough so the casing can be pressed into the top of the rock. The first section of casing has a drive shoe on the bottom end. The drive shoe protects the end of the pipe that is driven into the bed rock by the drilling rig. The casing seals off all surface water above the bed rock. After the casing is set then the 4-6” bit is lowered into the casing and is used to drill a 4-6” diameter hole into the rock. This is a better quality of water. The well driller goes as deep as needed in the rock to get enough water. So 70 ft is not far at all, I would have asked him to drill deeper. The 8” section is not as hard to drill because it is mostly in the soil but you have to pay for the cost of the steel casing. The 4-6” hole does not have the cost of the casing but drilling in the rock wears out the diamond bit and just takes more time. Some states require the casing to be grouted 20-35 feet deep. An over-reamer, looks like a giant hole saw, goes over the outside of the casing and bores down usually 20 feet. The annular space is about 2” around the outside of the casing is filled with concrete. The grout prevents surface water or contaminates from running down the annular space around the outside of the casing and seeping into the well at the base of the casing.
I'm not sure what it cost per foot these days. Normaly you would be charged so much per foot for the casing part of the well and usually a different price for the bore hole in the rock. The grout and slab would be extra. The cost can go up if the well is in a bad location etc.