GEOENVIRONMENTAL contractor Celtic Technologies has used bioremediation to deal with oil refinery tars at a site in southern Scotland.
The process, which uses microbes to break down and degrade contaminants, was used to clean up some of the hydrocarbons at Pumpherston, west of Edinburgh. Heavier tars were treated by soil mixing (GE February 1999).
Working for consultant The Robertson Partnership, the Cardiff-based contractor treated some 7,000m3 of tar on the 28ha site of the former Young's Paraffin Light and Mineral Oil Company oil shale refinery. Field trials were used to pick the best technique.
Tar was placed in batches in eight, 100m long treatment beds, each containing up to 20% dry (200,000mg/kg) weight diesel oil hydrocarbons and 550mg/kg polynuclear aromatic hydrocarbons.
Soil conditioning agents, nutrients and other amendments were added. Treatment lasted 8 to 10 weeks, producing an inert, humic soil. This was used during the site redevelopment as an extension to the adjacent nine-hole Pumpherston golf course, partly paid for by a £785,000 Scottish Sports Council Lottery Sports Fund grant.