Brownfields

Remediation of the old gas plant in Diest (Belgium)

Following the closure of the Diest gas plant, remediation of the site was required as the area was severely contaminated with BTEX, PAH's and cyanides.

DEC was awarded the job of selectively excavating 35,000 tonnes of contaminated soil, at depths of up to six metres in some places. Sheet-pile walls were installed to ensure the stability of excavations.

The contaminated soil was hauled away after excavation for thermal processing. Where possible, a portion was also cleaned physically/chemically in our own soil recycling centre in Kallo.

The groundwater was pumped up and purified in a water treatment system with a capacity of 30 m³/h. The key parts were the influent buffer, biorotor, stripper with aerated active carbon filter, hydrated activated carbon filter and ion exchanger. The BTEX contamination was removed in the stripper, PAH's were removed via the biorotor and activated carbon filter, and cyanides via the ion exchanger.

Because DEC designs and builds its own water purification plants, the company can always respond immediately to changing circumstances. A telemetrics system with alarm function alerts us to the most minor errors, so that we can respond very quickly and efficiently.