Correcting Common Water Well Problems
For water well drillers and pump installers, construction and installation are just one aspect of the job. Much of their time is spent responding to well problems and researching to choose the right troubleshooting methods. A wide range of issues can occur with water wells and when drillers run into them, figuring out the source and solution can be frustrating. Sometimes the answer to the problem is never found.
David Hanson, who founded Design Water Technologies in 1991, has spent more than five decades helping groundwater industry professionals and their customers tend to such matters. He got started developing products and practices for well problems to spread awareness that shock chlorination isn’t the answer to everything, to help drillers realize that the chemistry behind most problems is more basic than they think, and to foster safe approaches to problem solving. A master of the topic, he spends a good deal of time spreading his knowledge and experiences with drillers. At the 2015 South Atlantic Well Drillers Jubilee, he led a seminar titled “Understanding Your Well Problems.” In a follow-up interview with National Driller, Hanson reviewed some of the lecture, covering a few of the many issues he works with. Our interview is edited for space and clarity.
Q. What are the most common problems with wells you hear about?
A. Now I get calls from contractors more about coliform types of bacteria. Five years ago, I would get calls more about what everybody called iron bacteria because I was touting the fact that if we understand the problem and the problem is contained in the well, then the problem can be solved long term. Today’s issue on the market, we’ve eliminated all of the chemical aspects of failure. In other words, bleach has a tremendous shelf life and it loses 20 percent of its effectiveness every month and there’s no date stamp on the container, so when you buy it at the local store, you don’t know if it’s two or three months old — in other words if it’s almost wasted — or if it’s somewhat fresh.
Even if it is right off the manufacturer’s line, the product still is so pH sensitive that when you pour a little bit in, the pH raises and the effectiveness is down somewhere around 8 percent. If you use a lot of it, the effectiveness is maybe down around 1 percent. So in essence you’re wasting your time. Part of the problem I see with a lot of contractors is that they don’t often take into effect what their time is worth. So if they have to go out and re-chlorinate a well and then re-chlorinate it a second time and a third time, they don’t really understand their true cost of what that does to their bottom line.
Q. What’s the number one problem tied to corrosion?
A. Corrosion is often assessed to be iron bacteria. It’s often claimed that there’s a low pH, but what I see as the biggest problem with corrosion is total dissolved solids. That can cause what engineers call a galvanic corrosion or an electrolysis situation. It’s pretty easy to identify if you carry a small magnet with you. If you scrape some of that debris and crush it into a powder and put it on a piece of paper, you can actually assess some idea of the degree of corrosion due to the percentage of the metallic that’s in that debris. So if you check total dissolved solids and your TDS is 1,300, what happens in high total dissolved solids greater than, let’s say, 800 — and the greater the number the worse the problem — what you’re setting up is water that is highly conductive to energy.
So if you have dissimilar metals, let’s say low carbon steel and stainless steel, the low carbon steel will start suffering from corrosion and that energy will transmit to the stainless steel and you have corrosion on the lower noble metal, you have deposition on the higher metals. A simple solution is a magnesium rod, a sacrificial anode available at most pipeline companies and you can plastic band that to the pump below the pumping water level and what starts happening is that sacrificial anode starts suffering from corrosion and you have deposition on the next metals. So your problem is solved.
If you do your simple total dissolved solids test and you find your TDS is 320 or certainly lower than 500 or 600, you corrosion issues are not due to electrolysis. They might be due to other things. So when you do water quality you check pH, certain gases, but those have to be done with test kits at the well site itself. If you find all of those are negative, it’s awfully easy to get an electrician and start checking for DC voltage on the wiring going to the pump. One millivolt of DC energy will dissolve 12 pounds of steel in a year’s time. So if you have massive or early corrosion issues, the first thing that I would do is start checking for DC energy that may not be grounded properly.
Q. The idea that chemistry isn’t the answer to everything with respect to well problems is something you spent a lot of time going over. Could you elaborate on what you mean by that?
A. There are so many physical issues in wells. During the seminar I bring up an instance of where a contractor assumed that it was an iron bacteria problem, went to the distributor, purchased the amount of product that I designed for that specific well, and the chemistry wasn’t working. The contractor called and told me that because we give the contractor an actual monitoring procedure. After three hours, the contractor calls and says something’s wrong, nothing’s working — the pH isn’t rising, the color is a very faint yellow, which in our industry would indicate iron in solution, but being so faint there isn’t a lot of iron there. I asked him if he measured the bottom of the well. He did not, and with an 11-foot screen in that well he had 8 feet of fill and that fill seemed rather hard to the bailer, but he didn’t have a suction bailer to pull that debris out, so I told him to air lift it out and see what the debris was. The debris was very fine sand. So the problem was not an iron bacteria problem, it was fine silt and fine sand coming into the screen.
At a project in North Carolina, a municipality assumed they had black slime and did not want to do a simple sludge analysis, which was going to cost them $40. When I finally convinced the city engineer that I really need to see that debris, the debris did not respond to the in-the-field percentage of our normal chemistry in the lab. So when I took the debris out of the beaker and looked at just the debris under the microscope, it was extremely fine, very round silica debris. In other words, it was silt. The customer complained about a rotten egg odor. A rotten egg odor is most often caused by sulfate-reducing bacteria. They’re called sulfate-reducing because they secrete a corrosive enzyme and dissolve their favorite nutrient, sulfate, and then expel it as a gas.
Shales often have high sulfate, so to have that odor with this fine silt that we were seeing in both the wells, the city was having problem which indicated they had a physical problem in the well, not an iron bacteria or a slime bacteria problem. When we started looking at the well design and the well completion, the contractor found that the initial driller used neat cement as a grout, but then lost it totally into fractures of a hard rock formation and I think they lost it again.
Q. What’s the difference between a new well with odor and an old well with odor?
A. The age of the well can be critical with different types of odors. If a contractor drills a brand new well and he has a rotten egg odor, the rotten egg odor is tied to, generally, sulfate-reducing bacteria. Sulfate-reducing bacteria reduce sulfate. If you think about that nutrients, sulfates are often found in shales and clay, so if you drill a well in an unconsolidated aquifer and you screen it with too much screen, the screen can encompass some clay lenses where the sulfate-reducing bacteria are thriving and you can have that odor right away.
The direction is to shock chlorinate it, but you’re never going to get rid of the odor. So the only direction you can go at that point is to aerate the water, use a bladderless tank versus a bladder tank, put it into an open container or an open tank and let that odor escape. A very simple test to do is pour a glass of water, smell it right away. If you sense the odor, let it sit for 15 seconds, smell the water again and the odor is gone, that indicates that it’s a gas and it’s escaping into the environment. That means you can treat it and that’s the only way to successfully do it.
If in an older well never originally had an odor but all of a sudden does, then likely something has changed in the environment in the well or the system. So if it’s a domestic system you can go to the pressure tank. There’s generally a union joint somewhere on that line. If you drain the pressure tank and open that union joint, and inside that 1.25-inch pipe you only have a .25-inch hole in the middle, and that debris is soft and sludgy, what can happen is these sulfate-reducing bacteria can burrow into that debris and as the water keeps pulling off little segments of the debris inside the piping, exposing the bacteria below that, you get the odor you never had before. When customers explain the odor as musty or oily or metallic or iron in nature, if the contractor goes to that union joint in a domestic well and sees that type of debris, he has the opportunity to not only treat the well but clean the pipeline as well.
In a municipal situation you can do the same thing with submersible pumps. There might be a water meter. You can simply take the gasket off, look inside for that debris. If it’s a vertical hollow shaft turbine pump, there’s often a check valve right at the well itself. You can simply take the gaskets off that check valve, look inside for debris, there’s your answer.
Q. Could you talk about your response to drillers who say, “I wish I had a degree in chemistry”? Is such a degree necessary to master the kind of troubleshooting you do?
A. Not that the degree is important, because I don’t think it is. But the response that I got often after seminars were contractors that came up and said, “Wow. I wish I understood water chemistry. I wish I understood microbiology as much as you do, but I can’t.” Everything that I do in the seminar, called Understanding Your Well Problems, is really basic water chemistry. If you’re dealing with mineral deposits, those deposits will have a certain color. You don’t have to be a chemist to understand red, brown and yellow equals generally iron. You don’t have to be a chemist to understand that black and hard and brittle debris, when you strike a hammer on a piece of pipe, is manganese. White or tannish is generally calcium and blue or green is sulfate. So if you have blue or green debris and it’s hard, on your pump or on your drop pipe or on your screen, you wouldn’t be using sulfamic acid because you would fail. When it comes to mineral scale, everybody assumes mineral scale is mineral scale. If it’s hard, therefore it must be mineral. But the differentiation between corrosion and mineral deposits becomes clear if it’s magnetic.
Valerie King is associate editor of National Driller.