October 27, 2021
Abandoned or unused water wells can be found almost anywhere: on farms, industrial sites, and in urban areas. You may be able to easily spot a water well when they are marked by a windmill tower or an old hand pump. Others are not so clearly marked. Many abandoned water wells may lie hidden beneath weeds and brush, unsuspecting not only to children, hunters and animals, but an unlimited number of potential contaminants. Fuel, fertilizer, solvents, sewage, animal waste, pesticides, and other contaminants have all been introduced into groundwater through unsealed wells.
Each year, many unused wells are abandoned when they no longer serve a safe or practical purpose for accessing groundwater. In addition, wells are often abandoned when homes are connected to community water supplies or the quality of the water supply has degraded. According to the Ohio Water Resources Council, there is no accurate accounting of how many abandoned wells are in Ohio, but it’s estimated that tens of thousands of unused wells exist.
If you have a water well that is no longer in use on your farm or land, it’s important to properly seal it. Here’s why:
Protect groundwater quality
Throughout the landscape, there are potential conduits to drinking water underground, and water wells are one of those conduits. Old wells that have been abandoned are sometimes found in crop fields. By working with a qualified contractor through your local health department, you can properly cap the old well.
“By sealing any unused water wells that you have on your property, you are removing potential liabilities, “ states Jim Raab, Geology Program Supervisor, Division of Geological Survey at the Ohio Department of Natural Resources. “Sealing wells removes potential contamination pathways to the aquifer that you and your neighbors could be using for water supply.”
Sealing the old well eliminates the potential for contaminants such as nutrients and pesticides from directly reaching the groundwater. As a rule of thumb, if a substance can be dissolved, carried, or mixed in water, it has the potential for entering groundwater through an unsealed abandoned water well.
Prevent physical hazards
One of the more obvious reasons for sealing an abandoned water well is the physical dangers they present for the public and wildlife. Many of Ohio’s domestic wells fall in between the five to eight-inch diameter range, posing a potential hazard for children and small animals.
In addition, Raab says that “sinkholes” are another danger. Large holes in the ground develop when an improperly covered water well or buried dug well gives way. “These wells need to be sealed from the bottom to the top,” explains Raab.
Sealing an Unused Well
It’s highly recommended to seal wells with the help of an experienced registered water systems contractor due to the equipment and knowledge involved. According to the Ohio Department of Natural Resources, the basic procedures for sealing an unused well are:
- Remove all equipment such as pumps, pressure lines, etc. that may obstruct the placement and performance of the sealing agent.
- An attempt should be made to remove screens, casings and liners, although in many instances this may be difficult or impossible. If possible, the casing and/or liner should be slit, perforated, or ripped to allow the sealing agent to make the best possible seal.
- If the casing cannot be pulled, it should be cut off below ground level. The depth at which the casing should be cut will depend on whether the well was classified as public or private; in most cases, four feet will be sufficient.
- Ideally, the material used in sealing an abandoned well should reflect the surrounding geologic formations. Unfortunately, in most instances, the formations or their exact depths may not be known. Therefore, it is often hard to match the materials that should be used to the various formations. Many types of suitable materials are readily available for sealing abandoned wells. For best results, a bentonite clay should be placed in the well from the bottom up to the surface using a tremie pipe. As the well is filled, the tremie pipe should be moved upward until the entire borehole is sealed. This helps to prevent bridging of the sealing agent, which can occur when the sealing material is poured into the well. Some other acceptable sealing materials include neat cement or a combination of neat cement and bentonite.
- The location of the abandoned well and the specifics of the sealing procedure should be recorded and then reported to the Ohio Department of Natural Resources and other appropriate agencies (e.g. Department of Health, Ohio EPA).
To view the process of an old well capping at the Kellogg Farms demonstration site, visit the Abandoned Well Removal practice page.
For more information about well abandonment and its impact on water quality, please visit our resource library. If you have specific questions, contact your local OEPA district office, health department, or the Ohio Department of Natural Resources.