In my last several columns, I have written about selecting the proper openings for a water well screen and some popular installation methods. One thing we must do, however, before installing the screen is equip it with the proper fittings. Screens purchased from a manufacturer or supply house are not going to work as is (with a couple of exceptions).
If we are installing a drive point used when drilling a so-called stab well, that screen is going to have a point built into one end. We would merely thread the screen onto the first length of casing and hammer it into the ground. As these types of installations are not very popular, and indeed in some areas are illegal, I won’t say anything further about drive points. Likewise, if we are going to attach the screen to the bottom of the casing on a rotary-drilled hole, all we need is something to close the bottom end of the screen if it does not come equipped from the factory that way, and either thread, weld or glue it to our casing and in the hole it goes.
Start With the Plug
Columnist John Schmitt says that properly choosing the screen, riser, seal and plug will make for a long-lasting well and, in the end, a happy customer. Source: iStock
For the more “standard installation,” we are going to need three things: a cap or plug at the bottom, a riser pipe, and a seal at or near the top of the assembly. If we are using a threaded screen, a simple threaded IPS pipe plug is all we need at the bottom. This plug does need, however, to be strong enough to hold up against any tools we might run down inside the screen during development. I had a really disastrous job one time when the bailer I used on a repair broke the bottom plug and the screen filled with sand and gravel. I had to pull it and reinstall it, and it was a heck of a job.
After that sad experience, I installed solid-bottom plugs, not the cored type on most supply house shelves. These are extra thick and will withstand a considerable amount of abuse, unlike a cored plug. Another method that works pretty well is to weld a carbon or stainless steel plate on the bottom. Again, the plate needs to be pretty thick to have the strength. A -inch or 5⁄8-inch thick plate will usually do the job. Incidentally, threaded fittings don’t have to be made up pressure tight. They will actually work at little more than hand tight, although I usually tighten my fittings with a couple of small pipe wrenches.
Now, in the old days when we used lead packers (more about those later in this article) for a seal at the top of the assembly, we needed a bottom plug with a bail so we could lower the screen into the well and not just let it drop by gravity—especially if the well was deep. Bottom plugs with bails attached are available from screen manufacturers and are usually the same material: stainless steel, bronze, brass or what have you, as the screen itself.
On to the Riser Pipe
With the bottom of our screen sealed, we will need a riser pipe at the top of the screen, on top of which we will attach our seal. Every driller has his own idea of the proper length of a riser pipe. I have heard of folks who use a riser only 6-inches long. I personally preferred a 1-foot riser and other fellows I respect use 2-foot, 3-foot and even longer lengths of risers. The longest I have ever seen installed is a whole
21-foot length of pipe used by a driller I had subbed a job to. In this case, the riser was in my opinion overly long, but we had no shorter pieces of pipe of the proper length and the well was fairly deep with a high static level. If the well has a low static—that is it is perhaps only 10 feet above the screen—a short riser is almost required. Otherwise, we will not be able to use a submersible pump. I will say that with a riser of 6-inches or 1-foot, you better have pretty accurate measurements of the amount of casing that your well has and also your cable or drill pipe length. If you pull back and over expose, and the top of the screen goes out the bottom of the casing, you probably just lost the whole darn thing. In a rotary hole you might be able to get a hold of the screen and reinstall. In a cable-tool hole, this is just not going to happen.
Then, Seal It Up
The last part of our fittings lineup is going to be some sort of seal above the screen to keep sand and gravel from coming up around the riser pipe, falling back into the screen and plugging the whole works up. Years ago, drillers used burlap, rope or binder twine, even perhaps a combination of these to build a soft packer around the riser pipe. If this was properly made, the screen would rather easily slide down the casing and then swell after it entered the water. The bottom would probably be impregnated with a little bit of fine sand, making a water-tight seal. Applying these materials to a riser pipe was somewhat of a “by guess and by gosh” process, but with experience a driller knew about how much to apply to get a good seal. As it is very important to get a good seal between our riser pipe and the casing, this step should be done carefully.
In the age of newer bronze and stainless steel screens, many believed that these burlap/rope type seals would be destroyed by the acidizing process. Upon the advice of manufacturers, we then went to lead packers. A lead packer was made like a coupling that was half bronze or stainless steel, with the other half being thick lead ring. The lead could be anywhere from a - to a -inch thick, depending on the size of the casing. After we had pulled our casing back to expose the screen to the formation, we then went in with a swedge or some sort of tapered cone that would fit inside the packer. With this attached to our drill tools or a special swedging tool, we would expand the lead packer out against the casing for a sand-tight joint. These tools were available from some manufacturers.
From Lead to the K Packer
After using these lead packers for many years, some wise guy regulator decided that we were killing people with that lead in the water. It is funny how people lived long and productive lives without all the government regulations we have. My father grew up on a farm before he was a well driller and did all kinds of things in his lifetime that would be frowned upon today. He ate plenty of fatty foods, and smoked lots and lots of cigars. He was still driving at age 90 and lived to be 92 when he died peacefully in bed with all his fingers and toes, no cancers, no heart attacks and a healthy appetite to the very end. Makes me wonder if we really have made any progress.
Anyway, after the dreaded lead packer was banned from use we began to use what we refer to as a K packer. This has an interesting naming, in that I believe it came from the fact that one major screen manufacturer listed it and still does as a “figure K packer.” Just like Jell-o has become the name for the food gelatin, the K packer has become the name for the generic neoprene packer. These work very well with the exception that in some casings they fit a bit tight and the screen will have to be pushed to the bottom with our tool string and then held there as we pull our casing back (as I wrote in my last column).
Well, there we have our complete assembly: bottom plug, our screen itself, a length of riser pipe and a sand-tight seal at the top. If these are all chosen wisely, we should have a screen that lasts for many decades and a happy customer.
Sorry, but this column is about half again as long as desirable but the fittings all “fit” together, so to speak, and I hated to break this into two sections. I appreciate your patience in reading on and on. Next time, I will write about development methods for our well screen and then will move onto a new subject. I hope you had a wonderful Christmas and New Year, and life for you is good.
For more John Schmitt columns, visit www.thedriller.com/schmitt.