A Non-Reactive Gas System to Reduce Well Fouling and Maintenance of Extraction Wells

Chronic chemical and biological fouling of groundwater extraction wells can lead to high well-maintenance costs, increased pump downtime, and decreased pump efficiency. Commonly observed types of fouling include chemical precipitation of iron and carbonate minerals, bacterial accumulation, and oxidation in the pumping environment. Standard methods to rehabilitate and prevent fouling include chlorine treatments, acid and heat treatments, and physical scrubbing of screens and risers. Methods may effectively target one type of fouling while enhancing other fouling types. A down-well, fouling-prevention system was designed, tested, and then implemented on a sitewide basis at the former Bannister Federal Complex property in Kansas City, Missouri. Extraction wells at the site had a multi-decade history of chronic fouling. The antifouling system presented here creates an oxygen-deprived environment within the air column of the well through air displacement with a non-reactive gas. The removal of oxygen from the air column inhibits both biological activity and certain chemical reactions associated with fouling and does not require the use of chemical treatments or manual scrubbing. At the end of the year-long study period, chemical and biological fouling within the test wells was largely absent, whereas control wells undergoing chlorine treatment were heavily fouled and required rehabilitation.