Let’s Talk Well Rehab

Don’t overlook these common facets of well rehab.

By Gary Shawver, MGWC

When one hears well rehab, it often evokes well cleaning.

Wells in different parts of the United States have different well chemistry. When I say well chemistry, I’m referring to not only the natural mineral content of the water, but also potentially fouling bacterias such as iron-related bacteria and sulfate-reducing bacteria as well as others. Well chemistry is another topic that one could cover in a lengthy column, but I’ll leave that to someone more qualified on the subject than me.

In this column, let’s step back and think about the best approach to take when considering well rehab.

Know the Well’s Age and Water Quality

First, one should look at the age of the well. The age of the well will often give you an idea of how the well was constructed. It will show whether the well construction in and of itself is an issue with the fouling.

If the well is more than 50 years of age, the well is most likely constructed of steel casing. In my experience, wells constructed of steel casing will last a minimum of 40 years to a maximum of 100 years.

As always there are exceptions. An important question to consider: Would the money being spent on well rehab be better off going towards a new well?

If the well is older, it may not have been grouted. Is the lack of grout contributing to the fouling of the well? For example, is water potentially migrating down along the outside of the casing, bringing iron-related bacteria or potentially a water that is higher in natural iron or other undesirable minerals that is fouling a better-quality aquifer?

An experienced well contractor will often know the water quality that one can expect from a newly constructed well in a given area.

Second, test the water quality before the well rehab is conducted. Basic tests should include, but not necessarily be limited to, iron-related bacteria (IRB), natural iron, manganese, hardness, total dissolved solids (TDS), as well as coliform bacteria and in some areas of the United States, nitrates and arsenic.

Of these basic tests, coliform, nitrates, and arsenic are health-related tests. If one or all of these are testing potentially unsafe, then you may wish to rethink a well rehab. Again, the age of the well can come into play on this.

For example, if the well is newer and drilling another well to get away from the nitrates or arsenic is not an option, then treatment of the water for these two issues is the only way to go.

If the well tests high in coliform bacteria, one should look at what may be causing this issue. The point is not to jump into a well rehab and spend the money just to find the customer still has an issue that needs remedied.

If the well has a high IRB or high mineral/TDS content, then this information will help you to know how severe the problem is and how to potentially deal with it. There are many products on the market that are specifically designed to remove encrustations and help remove IRBs. Most of these products work well but following their guidelines on use is imperative.

Depending on the lab being used, IRB can be tested at differing levels. For example, some labs will report IRBs in minor infestations, moderate infestations, and heavy infestations.

If the well has a moderate to high level of infestation, getting rid of this through well rehab and chemical treatment can be extremely difficult—especially if the well is older and has never been treated or rehabilitated in the past. I would caution on how successful one might be in an attempted rehabilitation of a well with moderate to high infestations.

Type of Well Makes a Difference

Before initiating well rehabilitation, it’s important to acknowledge the type of well you’re working with. For example, is it a screened well or is it an open-bottom consolidated well (finished in limestone, sandstone, or granite)? And if it is an open-bottomed well, how many feet of open well is there to treat?

A screened well, especially a domestic/farm type well, often has a short section of screen (3 inches to 10 inches). This type of well is relatively easy to treat as you have a small water-bearing formation area.

Whereas if you have an open-bottomed well of several hundred feet, this is more difficult to treat, especially if it has several water-producing zones. In this case, it is helpful to have a good well record showing where those water-producing zones are, so you can focus on treating them.

In either of these cases (a short section of screened well or an open-bottomed well), this does not preclude the need of cleaning the entire length of the casing, especially the section exposed to water.

It is also important to discuss the history of the well with the homeowner unless you have been involved in the well maintenance since its beginning.

For example, I once was called to an older farm well where the pump contractor had been involved in the well maintenance for years. In discussing the well problem with the owner and pump contractor, I found that the well pump had been replaced annually, almost to the day. IRBs were fouling the pump and causing it to fail.

This immediately pointed to well replacement rather than attempting treatment. We moved approximately 1000 feet away from the existing well and drilled a new well to the same depth as the old one. We then properly abandoned the old well. When the new well was completed, we checked both the IRB content and iron content of the water and found the well absent of IRBs and a low concentration of iron.

If a new well is to be considered for replacement in a case such as this, it is imperative to move as far away as possible from the existing well so as not to draw the IRBs into the new well.

However, this may not always be possible. In this case, there were only two options for a new well: one at approximately 200 feet in depth and another at over 800 feet in depth. We opted for the shallower depth due to the distance we were able to obtain (1000 feet) from the existing old well.

Well Cleaning Tips

If you are to the point where you determine treatment is the direction you are going to go on a well, it is important that you clean the well with a brush that is designed for well cleaning. There are several types of brushes available from industry manufacturers. If you are unsure what type of brush to use, call the various vendors that sell these brushes and speak to them. Getting a tight-fitting brush, typically with
non-steel bristles (nylon or something similar), is the brush of choice.

Cleaning the well with a mechanical action of the brush prior to chemical treatment is recommended. It is also imperative to remove this debris from the cleaning prior to the chemical treatment.

Application and installation of the chemicals per the manufacturer’s recommendations is also vital. Often it may take several applications of chemicals before the infestation or encrustation is removed.

Upon completing treatment of the well, it is imperative to use a pump of much higher capacity than the existing well pump and then pump the well to maximum capacity for several hours. Testing the water for the minerals one is attempting to remove is also important during this pumping period.

Early in my career we were cleaning a screened well that had never been treated before. The iron content in the well was high. After the cleaning, we put the owner’s pump back in, pumped the well for about an hour, and put the well back in service.

A few days later the owner called and said his iron content was worse than ever. We went back to test the water and found it off the chart on iron content. Realizing that we may not have removed the broken-down iron concentration in the well, I used a pump that was capable of 50 gpm and pumped the well for six hours. The iron content started out extremely high but after six hours was down to approximately 1 part per million. We put the owner’s pump back in and the problem was solved.

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While I have not covered every facet of well rehab and problems associated with it, I have tried to cover some common facets that one overlooks when a well rehab is considered. Obviously, there is much more that can be covered regarding well rehab than is allowed in this space.

In summary, well rehab is not a simple, straightforward science. Every well is unique in its problems and its history. Do your homework and evaluate the full scope of the potential problems and options before engaging in well rehabilitation.

And while I don’t want to sound like well rehab is a facet of the industry to stay away from, I will say the more experience you obtain doing well rehab, the more the next one will be that much easier. Experience is a dear teacher and experience is what keeps you in business.

DACUM Codes
To help meet your professional needs, this article covers skills and competencies found in DACUM charts for drillers, pump installers, and geothermal contractors. DO refers to the drilling chart and GO represents the geothermal chart. The letter and number immediately following is the skill on the chart covered by the article. This article covers: DOF-1, 2, 3, 4, 5, 6, 7. More information on DACUM and the charts are available here.

Gary Shawver, MGWC, is president of Shawver Well Co. Inc. in Fredericksburg, Iowa. He has been in the water well industry for more than 40 years and is a Master Groundwater Contractor. He served on the NGWA Board of Directors. Shawver is semi-retired, having sold his business to his employees. He can be reached at grs@shawverwell.com.