Hiring a professional the safest way to decommission inactive water wells
With concerns over the quality and sustainability of water sources on the rise, more and more producers are becoming aware of the need to properly plug — or decommission — old, unused water wells on their farms to avoid costly water contamination issues down the road. With that interest comes a producer demand for solutions that are as simple, practical and inexpensive as possible.
The problem is, when it comes to decommissioning water wells, the answers are just not that easy. "The bottom line is that decommissioning a water well can be complex and expensive and the more we learn about it, the more we learn just how many things can go wrong when producers attempt to do it themselves," says Joe Harrington, a water specialist with Alberta Agriculture and Food (AF).
"That's why we recommend letting a professional do the job. Although hiring a contractor may cost more initially, it can save producers a costly clean-up process of an independent attempt that is not done right. And when it comes to decommissioning water wells, it pays to get it right the first time."
The reason water specialists are learning so much more about decommissioning water wells is simply because more producers are recognizing the legal responsibilities and environmental benefits of doing so, says Harrington. As a result, certain practices are taking on new profile. A major example is the importance of properly filling in the annulus — the space between the well casing and the inside of the drill hole.
"Because the well casing has to be slightly smaller than the drill hole in order to fit, you wind up with a one to two inch gap called an annulus. If not filled in properly, this gap can provide a direct line for contaminated groundwater to drain down into the aquifer. When this happens, the landowner frequently doesn't know there's a problem until the groundwater is already contaminated."
The main factor that drives producers to attempt to decommission a well themselves is the cost of hiring a professional such as a well driller. Although hiring out can be expensive depending on the difficulty of the decommissioning project, Harrington says letting a professional do the job is usually the best option.
"A professional will know what's involved in fully decommissioning a well so it no longer presents a contamination threat," he says. "They will also have the necessary tools to do the job right. Some producers think they can dump anything into the well and consider it decommissioned, but it's not that easy."
One example of a step in the process that can sometimes create difficulty is pulling the well casing out of the well. "Well drillers will almost always try to pull the casing, but that can be almost impossible when it's either stuck or so corroded that it would fall apart in the process," he says.
"In those cases, well drillers would make sure the non-permeable filling material, such as bentonite or cement, is pumped through perforations they make in the casing so both the well casing and the annulus are sealed from the inside out."
Wells are constructed in many different ways and there are instances in which those extreme measures do not need to take place, says Harrington.
"Some wells do not have a liner, so they only require the bore-hole to be filled with bentonite or cement," he says. "In these cases, after consulting with a professional such as a well driller, it may be possible for the well owner to complete the project by carefully pouring bentonite chips or pellets down the well and filling it from bottom to top. In all cases, wells should be shock chlorinated before being plugged."
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Article development courtesy of The Alberta Environmental Farm Plan Company