“Let Me Tell Ya”: Water Well Casing - Got to Keep That Soil out of Our Borehole
In the many columns that I have written, I have
covered several types of drill rigs, numerous types of pumps, and even drop
pipe. The one thing all of these subjects have in common is that they are part
of a water well system. One of the most important parts of a properly
constructed water well is the casing, even if bedrock is very near the surface,
and collapse of the borehole is not going to happen in that formation. Most
well construction codes require a minimum depth of casing, which, in the
bedrock, would be installed into an oversized hole, and the annulus grouted
full, usually with neat cement, but sometimes with other
materials.
Here in southern Michigan, we have a wide variety of geologic formations right up to the surface. Where my business is located, the bedrock is several hundred feet deep. If one goes 25 miles west of my location, you can expose the bedrock with your boot, as the drift or overburden is a foot or less deep. I don’t know the maximum depth of the drift in Michigan, but I am aware of a well in the northern Lower Peninsula that is 875 feet deep, and still is in the unconsolidated drift. The majority of drilling I have done in my career has been either 2-inch or 4-inch IPS size casing. I have drilled a number of 3-inch wells, some 6-inch and a few 11⁄4-inch stab-type wells.
Probably the most unusual size that my dad or I ever drilled was a well with 21⁄2-inch casing. This was a goofy size if ever there was one. And that size pipe is fairly weak in the joints, as that is the size where the thread form goes from 11.5 threads per inch to eight threads. The coarser thread tends to more nearly cut through the wall thickness of this 21⁄2-inch pipe than it does in other sizes. As a result, 21⁄2-inch pipe is more prone to breakage in hard driving conditions. We used the 21⁄2-inch size because we could use a larger drop pipe on jet pumps, and get a lot more water from the pump than we could with a 2-inch casing. I always felt that the 21⁄2-inch size had all the disadvantages of a 2-inch, and none of the advantages of a 3-inch, 4-inch or larger well.
When I started to go with my dad as a helper in the mid 1940s, he was drilling primarily 2-inch wells, pretty much all of which were completed in sand-and-gravel formations. We strictly used galvanized casing – a fact that I will speak more about later in this article – in 21-foot lengths. We were installing this casing by the hydraulic, and sometimes jetting, method. One of the problems that was special to 2-inch casing is that it bent pretty easily. Unfortunately, we have more than our fair share of boulders in this area, and we bent a number of casings. When this happened, we had to pull out the casing, and replace the bent section with a straight one. An interesting fact was that most of the first or deepest length of casing had no galvanizing on it at all when we pulled it out.
In an attempt to improve the quality of our product, my dad went to the aforementioned goofy 2-1⁄2-inch size, also in galvanized, and which was somewhat stiffer than the 2-inch, and eventually to 3-inch casing in both galvanized and black. We were installing these all by the hydraulic and jetting methods we had used for the 2-inch. I know some fellows drilled 3-inch using the cable-tool method, and I have seen in older catalogs cable tools that will fit into a 2-inch casing. I have never seen these 2-inch-sized cable tools, or heard of anybody using them. If any of you readers ever had any experience with these, I would be very interested in hearing from you. One of the big advantages of the 3-inch well was that one could get a good-sized screen into it at completion, and this screen life was much, much longer than the screens in 2-inch wells.
Eventually, with the popularity of submersibles, we decided – or were perhaps forced – to go to 4-inch casings. These we drilled by the cable-tool method. We used just about all black steel casing, with some galvanized, in the 1980s. Just like starting a brouhaha over who made the best drill rig, a touchy topic at a drillers’ meeting, was whether one should use black or galvanized casing. I have heard some experts present the opinion as recently as the spring of 2012 that galvanized steel should never, ever be used in a water well. It has something to do with a fact that a pipe wrench possibly could cut through the galvanizing while tightening joints, and this small wound to the surface of the pipe can become part of a dissimilar metal reaction – I’m not quite sure that I understand this, but some pretty knowledgeable people have told me that galvanized and well casing don’t mix.
In all of these casings, we used pipe that was listed as T&C – R&D. The T&C stood for threaded and coupled, and R&D, I understand, stood for reamed and drifted. The couplings on this casing were of the tapered type and extra long, so that when properly made up, a joint exposed no threads to the earth. I do know some fellows who used regular plumbing-type couplings and these, of course, are a straight thread. We never used these in any well casing, and I don’t know if they were that much of a disadvantage or not. The R&D designation meant that the threaded ends of the pipe were well-reamed on a taper, so a drill bit or anything else going through the inside would not stick. Likewise, drifted meant that a drift tool was run the entire length of each piece to ensure that no scale, weld beads or other projections were on the inside bore.
We did drill some 6-inch wells by cable tool, and these were no different than 4-inch; we just used a bigger drill bit and heavier tools. I did drill a few shallow 8-inch wells, but that is as big as I ever did. Next time, I will talk about welded casing, joint lengths, casing’s effect on capacities, and drive shoes.
As I write this on a Sunday afternoon in late July, the temperature is in the high 80s, and it also is very humid. It is very, very, very dry; our lawns are all brown, and about 90 percent of our corn and bean crops might as well be turned under – they are shot. We have not had significant rain in weeks, and I know now what you folks in some of the drought states have gone through. We usually get cool nights even on hot days here in Michigan, but that has not happened. It has been a very unpleasant summer so far. Keep cool while drilling, drink plenty of liquids, and use the casing that fits your needs best.
ND
Here in southern Michigan, we have a wide variety of geologic formations right up to the surface. Where my business is located, the bedrock is several hundred feet deep. If one goes 25 miles west of my location, you can expose the bedrock with your boot, as the drift or overburden is a foot or less deep. I don’t know the maximum depth of the drift in Michigan, but I am aware of a well in the northern Lower Peninsula that is 875 feet deep, and still is in the unconsolidated drift. The majority of drilling I have done in my career has been either 2-inch or 4-inch IPS size casing. I have drilled a number of 3-inch wells, some 6-inch and a few 11⁄4-inch stab-type wells.
Probably the most unusual size that my dad or I ever drilled was a well with 21⁄2-inch casing. This was a goofy size if ever there was one. And that size pipe is fairly weak in the joints, as that is the size where the thread form goes from 11.5 threads per inch to eight threads. The coarser thread tends to more nearly cut through the wall thickness of this 21⁄2-inch pipe than it does in other sizes. As a result, 21⁄2-inch pipe is more prone to breakage in hard driving conditions. We used the 21⁄2-inch size because we could use a larger drop pipe on jet pumps, and get a lot more water from the pump than we could with a 2-inch casing. I always felt that the 21⁄2-inch size had all the disadvantages of a 2-inch, and none of the advantages of a 3-inch, 4-inch or larger well.
When I started to go with my dad as a helper in the mid 1940s, he was drilling primarily 2-inch wells, pretty much all of which were completed in sand-and-gravel formations. We strictly used galvanized casing – a fact that I will speak more about later in this article – in 21-foot lengths. We were installing this casing by the hydraulic, and sometimes jetting, method. One of the problems that was special to 2-inch casing is that it bent pretty easily. Unfortunately, we have more than our fair share of boulders in this area, and we bent a number of casings. When this happened, we had to pull out the casing, and replace the bent section with a straight one. An interesting fact was that most of the first or deepest length of casing had no galvanizing on it at all when we pulled it out.
In an attempt to improve the quality of our product, my dad went to the aforementioned goofy 2-1⁄2-inch size, also in galvanized, and which was somewhat stiffer than the 2-inch, and eventually to 3-inch casing in both galvanized and black. We were installing these all by the hydraulic and jetting methods we had used for the 2-inch. I know some fellows drilled 3-inch using the cable-tool method, and I have seen in older catalogs cable tools that will fit into a 2-inch casing. I have never seen these 2-inch-sized cable tools, or heard of anybody using them. If any of you readers ever had any experience with these, I would be very interested in hearing from you. One of the big advantages of the 3-inch well was that one could get a good-sized screen into it at completion, and this screen life was much, much longer than the screens in 2-inch wells.
Eventually, with the popularity of submersibles, we decided – or were perhaps forced – to go to 4-inch casings. These we drilled by the cable-tool method. We used just about all black steel casing, with some galvanized, in the 1980s. Just like starting a brouhaha over who made the best drill rig, a touchy topic at a drillers’ meeting, was whether one should use black or galvanized casing. I have heard some experts present the opinion as recently as the spring of 2012 that galvanized steel should never, ever be used in a water well. It has something to do with a fact that a pipe wrench possibly could cut through the galvanizing while tightening joints, and this small wound to the surface of the pipe can become part of a dissimilar metal reaction – I’m not quite sure that I understand this, but some pretty knowledgeable people have told me that galvanized and well casing don’t mix.
In all of these casings, we used pipe that was listed as T&C – R&D. The T&C stood for threaded and coupled, and R&D, I understand, stood for reamed and drifted. The couplings on this casing were of the tapered type and extra long, so that when properly made up, a joint exposed no threads to the earth. I do know some fellows who used regular plumbing-type couplings and these, of course, are a straight thread. We never used these in any well casing, and I don’t know if they were that much of a disadvantage or not. The R&D designation meant that the threaded ends of the pipe were well-reamed on a taper, so a drill bit or anything else going through the inside would not stick. Likewise, drifted meant that a drift tool was run the entire length of each piece to ensure that no scale, weld beads or other projections were on the inside bore.
We did drill some 6-inch wells by cable tool, and these were no different than 4-inch; we just used a bigger drill bit and heavier tools. I did drill a few shallow 8-inch wells, but that is as big as I ever did. Next time, I will talk about welded casing, joint lengths, casing’s effect on capacities, and drive shoes.
As I write this on a Sunday afternoon in late July, the temperature is in the high 80s, and it also is very humid. It is very, very, very dry; our lawns are all brown, and about 90 percent of our corn and bean crops might as well be turned under – they are shot. We have not had significant rain in weeks, and I know now what you folks in some of the drought states have gone through. We usually get cool nights even on hot days here in Michigan, but that has not happened. It has been a very unpleasant summer so far. Keep cool while drilling, drink plenty of liquids, and use the casing that fits your needs best.
ND
Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!
