Permeable Reactive Barriers

The reactive media is selected to absorb the pollutants from the groundwater or to convert harmful chemicals to harmless by-products. Typical examples of reactive media are:

• Activated carbon for absorption of organics
• Ion exchange resins for adsorption of metals and radionuclides
• Zero valent iron for dechlorination of halogenated solvents, absorption of carbon disulphide or reduction of oxymetal ions (e.g chromate)
• Limestone for precipitation of metals
• Sand/gravel beds with the addition of nutrients and oxygen to promote microbial degradation of organic contaminants

Cleaning groundwater with a PRB may take many years. The time taken depends on the amount of pollution present in the groundwater and how fast the groundwater moves through the PRB.

There are several advantages of using a PRB to remediate contaminated groundwater:

• The installation is beneath ground preventing human contact with the contamination
• Low operating and maintenance costs
• No energy requirement as the system relies on natural groundwater flows
• No pumps, moving parts or associated noise
• Invisible after installation
• Allows continued use of the site after installation

PRBs have been installed at more than 80 sites in Europe and North America. Keller participated in the installation of the first PRB's in the UK. Contact Keller for advice about applications, reactive media and the optimum design and engineering solutions for PRB construction / installation.