Six of our client’s water-supply wells pump water from a groundwater plume containing chlorinated solvents. Those wells serve as a city’s primary water-supply source and as a remediation system to control the migration of the groundwater plume. The solvents in the extracted water are removed to non-detectable concentrations using granular activated carbon (GAC) in a Barr-designed treatment plant. In 2014, the compound 1,4-dioxane was detected in the treatment-plant effluent at concentrations above the health-based value set by the Minnesota Department of Health. For the client to continue drawing this water for potable use, additional treatment was required to remove 1,4-dioxane.
Barr designed and operated an eight-month pilot study to evaluate two advanced oxidation process (AOP) technologies for removal of 1,4-dioxane—low-pressure UV/peroxide and ozone/peroxide.
Pilot testing indicated that both AOP systems remove dioxane to target limits. In this application, the ozone/peroxide system was eliminated due to production of undesirable bromate concentrations as a byproduct of the reaction of naturally occurring bromide and ozone. High levels of bromate in drinking water have been associated with elevated health risks. Following pilot testing, Barr designed the full-scale treatment-plant modifications, which were completed in 2019.
Senior Civil Engineer
Vice President Chief Operating Officer