Research and Development Office

Developing and Testing an Engineered Biological Control for Iron Oxidizing Bacteria in Water Wells

Project ID: 23032
Principal Investigator: Teigan Struck
Research Topic: Water Quality
Funded Fiscal Years: 2023 and 2024
Keywords: None

Research Question

This research is based on the hypothesis that inhibiting the growth of, or eliminating, FeOB in groundwater wells will eliminate or significantly slow the production of adverse byproducts of iron oxidation that inhibit pumping rates and lead to premature well failure. The research will answer the following questions:

Can chemical, microbiological, and solid-state characterization be used to identify primary factors leading to premature well failure?

Can genomic sequencing identify target gene sequences in the FeOB genome that can be targeted using bioengineered treatments (CRISPR gene editing, bioaugmentation, or similar) to prevent or inhibit iron oxidation?

Can bioengineered treatment methods (CRISPR-Cas9 nuclease with synthetic guide RNA variants, bioaugmentation or similar) be delivered successfully in laboratory and field settings to mitigate/eliminate FeOB?

As an ancillary benefit, can data collected during this research inform parameters within groundwater wells that influence the proliferation of FeOB?

Need and Benefit

Need:
YAO manages 111 groundwater pumping wells. These wells primarily serve to lower the regional groundwater table for productive agriculture. Water pumped from these wells provides supplemental benefits by augmenting water supply and managing salinity in the Colorado River. The leading cause of premature failure of these wells is Iron Oxidizing Bacteria (FeOB). FeOB are some of the most common bacteria found in water wells. FeOB are chemotrophic and derive energy from oxidizing dissolved ferrous iron, which then reacts with water to form iron oxyhydroxide, a dense, slick substrate with a signature brown-orange color. The bacteria then collect this material and form thick stalks which are notorious for accumulating into a biofilm that blocks well screens and pumps, hindering flow and limiting well production. Soft and pliable initially, these deposits harden and adhere to the well material and surrounding formation. These deposits can also accelerate corrosion of metal well components.

In one YAO well, it was observed that pumping rates dropped nearly 40% within the first 4 months of pumping at the designed capacity of 3100 gpm, and within three years, the well was 90% diminished to a maximum rate of approximately 300 gpm and was ultimately taken offline. When well pumping rates drop 25% or more, it is typical for rehabilitation efforts to take place to regain pump capacity of a well through physical removal or chemical disinfection, including: brushing, surging a well, redevelopment, simple chemical treatment – chlorine/acid. These methods are generally ineffective at impacting the biofilm and mineralization that occurs from the well screen outward into the surrounding soil. These methods are also typically undertaken reactively, often after they are likely to be successful.

Benefit:
YAO expends millions of dollars annually to replace drainage wells that no longer function effectively through FeOB deterioration and clogging. Wells are redrilled years and often decades before their expected end of serviceable life. Over 30% of YAO wells have been replaced within the last ten years. YAO wells have an average age of approximately 27 years. With effective treatment for FeOB, YAO anticipates that the average well age could be increased to approximately 40 years. This would reduce the need for well replacements from the current rate of 4.1 wells per year to a rate of 2.8 wells per year. This would reduce capital investment needs for YAO by an estimated $1.3 MM per year.

Urgency/Consequences:
Reclamation and YAO are currently resigned to the reality of the limitations of existing FeOB treatment methods. Without research into new treatment approaches, YAO will continue to expend a significant portion of O&M funding on labor intensive physical removal, chemical treatments, and premature well replacements. The unreliability of water supplied by these wells during the ongoing watershed drought hampers the ability to meet our mission.

YAO expends millions of dollars annually to replace drainage wells that no longer function effectively through FeOB deterioration and clogging. Wells are redrilled years and often decades before their expected end of serviceable life. Over 30% of YAO wells have been replaced within the last ten years. YAO wells have an average age of approximately 27 years. With effective treatment for FeOB, YAO anticipates that the average well age could be increased to approximately 40 years. This would reduce the need for well replacements from the current rate of 4.1 wells per year to a rate of 2.8 wells per year. This would reduce capital investment needs for YAO by an estimated $1.3 MM per year.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Contact the Principal Investigator for information about these documents.

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