Remediation of a site contaminated with creosote and CCA - a case study

IRG/WP 98-50101-12

T Rødsand, K Hellum, H Lillemaehlum

Over sixty years of wood preservation activity conducted by ImpregNor at Ilseng, Norway, has caused serious contamination of the soil. High concentrations of creosote have been found at two separate sites, one in connection to the creosote wood preservation plant, and one further downstream were residues from the creosote preservation have been deposited. High levels of chromium, copper and arsenic (CCA) are found in a third area around the CCA wood preservation plant and the related dripping/fixation area. A site investigation of the contamination situation revealed that both creosote and CCA were spreading out of the wood preservation plant area directly through the sewer and drainage systems and with the ground water. There was no acute danger for exposure to humans, but further spreading would increase the exposure risk. A remedial actions plan to prevent further spreading of contaminants was requested by the Norwegian Pollution Control Authorities in July 97. Three drainage trenches for the collection of groundwater have been constructed downstream from the contaminated areas. The trenches were excavated down to a confining low permeable clayey silt layer. HDPE membranes on the downstream wall of the trenches prevent contaminated water from migrating across the trenches. Free phase creosote and creosote contaminated water from the trenches are pumped through an oil separator constructed to remove creosote oil. The groundwater from the CCA contaminated area is collected and pumped through a sedimentation basin and reused in the preservation plant. Control of the effluent during the first six months will show if further water treatment is required. The use of in situ bioremediation to increase the remediation rate of the creosote contaminated areas will be further investigated to limit the duration of the "pump and treat" operation.


Conference: 98-02-02/03 Cannes-Mandelieu, France

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