Brownfields

Remediation of a former gasworks in Dublin (Ireland)

The soil at this former gas plant was severely polluted with tar and tarry products. The groundwater was also polluted with contaminants that were directly connected with gas extraction from coal, such as aromatics, PAH's and cyanides. The plot is in the docklands of Dublin and its remediation was part of the redevelopment of the property to be used as a residential and business zone.

Remediation activities:

• The site was completely sealed off by a bentonite wall that will prevent contamination from spreading in the future.
• Waste products from the site had to be removed: liquid tar (1,300 tonnes), viscous tar (20,000 tonnes) and free oil products.
• The top layer of gravel was excavated and washed. Then it was reused on the site (38,000 m³).
• The contaminated soil was excavated and shipped to Europe for further treatment and reuse. 170,000 tonnes were treated by physical/chemical washing, 130,000 tonnes treated via thermal desorption.
• The contaminated groundwater was pumped at an average volume of 500 m³ per day and treated via aeration, coagulation/flocculation, sedimentation, sand filtration and activated carbon filtration.