By Michael J. Schnieders, PG, PH-GW
Per NASA, corrosion can be defined as the degradation of a material due to a reaction with its environment. Degradation can be physical deterioration or weakening of the material and at a minimum, releases components (such as iron) into the surrounding environment (e.g. water flow).
Many of us in the groundwater industry have long argued corrosion is a more significant problem than the water industry as a whole recognizes. For years, we’ve had to face growing costs to treat iron at the surface while well construction projects are pushed to a cheaper and cheaper budget. Iron, one of the more common elements of concern in produced water quality, is more often a problem resulting from corrosion of the well structure than it is from the aquifer.
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Spanning the Industry
To be blunt, the problem spans the industry. Many well owners, regulators, and contractors don’t understand corrosion, and worse, don’t understand the need to understand it.
Corrosion, or the tendency for corrosion to occur, is not a regulated water quality parameter. While many of the parameters required to calculate basic corrosion indices are part of base line water quality analysis, it is an assessment commonly ignored.
Part of the issue is corrosion is not a simple issue to evaluate. Groundwater chemistry is a major contributor, as is microbiology, but corrosion also concerns the well structure and materials used, the way the well is operated, and the environment in which the well is located.
The crisis that hit Flint, Michigan, in 2014 and 2015 pivots on corrosive water chemistry and a true misunderstanding and resulting misapplication of infrastructure and treatment technology. The results of this misunderstanding have and will continue to have far-reaching impacts on drinking water—both surface and subsurface sourced.
A U.S. Geological Survey study in 2016 focused on the corrosivity of groundwater in the United States. The study assessed more than 20,000 wells nationwide and evaluated several parameters that influence the rate of corrosion. The results show half of the states have either “high or very high potential to be corrosive.”
Look at the System
While the study is reported to have the greatest impact on private well owners, we feel it will be an important part of resource planning for all municipalities and utility providers. By focusing on multiple parameters and conditions, it raises awareness of a very important concern.
Responding to corrosive water goes beyond using stainless steel in one part of the well; we must look to the well as a system. This accounts for the occurrence of sediment, flow profiles, microbiological communities, water chemistry of the well and aquifer, and the materials selected for construction, from the column pipe to the screen and the casing to the centralizers.
Michael J. Schnieders, PG, PH-GW, is a professional geologist currently serving as the principle hydrogeologist and president of Water Systems Engineering Inc. in Ottawa, Kansas. Schnieders’ primary work involves water resource investigation and management, specializing in the diagnosis and treatment of fouled well systems. Schnieders has been named the 2017 McEllhiney Distinguished Lecturer in Water Well Technology. He can be reached at: firstname.lastname@example.org[/restrict]