WITHDRAWN - Challenges of Iron in Groundwater Remediation Projects – A Case Study

Naturally occurring iron in the dissolved form is commonly found in groundwater across North America. This seemingly harmless compound can lead to a number of challenges for environmental engineers working to remediate properties with groundwater contamination where dissolved iron is present.

Iron in the dissolved form will readily convert to a rust colored precipitate called iron oxide when exposed to air in recovery wells, pneumatic pumps, vacuum extraction process lines, air strippers, and tanks. Iron oxide particles are typically in the range of 0.5 micron to 2 micron and can bind up to form larger particles. Once in the oxidized form, iron will settle and plug piping, tanks, reinjection wells, carbon filters, air strippers and bag filters, which result in ongoing operating and maintenance challenges and operating cost overruns.

The discharge of iron-impacted water is highly regulated in most regions. This is primarily due to the oxidation potential of dissolved iron, which consumes oxygen from rivers and streams, as well as the increased turbidity, and sedimentation of precipitated iron. The increasingly stringent regulations for iron-impacted water require remediation engineers to remove the iron prior to discharge in many applications.

newterra, working with a team of environmental consultants, experienced these challenges first hand on a brown-field redevelopment site in Belleville, Ontario. On this site, groundwater levels are monitored and controlled to prevent the flow of contaminated groundwater off the property.

newterra will present a case study on this project explaining the challenges found on this site, the process followed to qualify and quantify the iron problems, and the steps taken to narrow down the best treatment solution. In addition, the case study will describe the technology chosen to manage the iron problems on the project.