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Soil contamination: Steam remediation of contaminated sites
A Danish EPA report shows that steam can be used to remediate sites contaminated with chlo-rinated solvents. Over a three-year period a contaminated site has been remediated so well that 95% of the area can now be used for housing without the risk of harmful vapours indoors. This is also good news for the drinking water supply since the site lies within the groundwater capture zone for 15% of the drinking water supply for Copenhagen County.
In all, Copenhagen County has remediated 90,000 tonnes of soil at an 8,200 square metre site near Roskilde, removing approx. 800–1,000 kg of chlorinated solvents down to a depth of approx. 9 metres. The steam was distributed through the soil via 10 kilometres of pipe and 147 steam injection wells.
The project can prove to be of significance for many of the approx. 14,000 contaminated sites in Denmark that are waiting to be remediated. Many of them are contaminated with chlorinated solvents. Traditional remediation methods based for example on pump and treat technologies are often time-consuming and expensive. New, more effective methods are therefore needed.
Steam remediation releases the solvents from the soil by heating. Thereafter the solvents are removed by means of a ventilation system and by abstracting the groundwater. The steam remediation phase of the project lasted three years. Remedial pumping is required for a further 8–10 years in order to reduce the remaining contamination.
The new method provides an important choice in the efforts to remediate sites that are contami-nated with chlorinated solvents.
Further information: Inger Asp Fuglsang, Danish EPA. Phone: +45 3266 0100. E-mail: iaf@mst.dk.
Project summary and conclusions (report in Danish, summary in English): http://www.mst.dk/udgiv/publikationer/2004/87-7614-049-0/html/kap02.htm
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