Proper removal and disposal
The contaminated site N68 “Krinninger roofing felt factory” in Brunn am Gebirge was located on the premises of the former Brunner Glasfabrik (“Brunn Glass Factory”) and, before that, Erste Brunner Dachpappen Fabrik Julius Krinninger u. Comp (“First Brunn Roofing Felt Factory Julius Krinninger & Co.”) which had been founded in 1888. The latter seized operations around 1940 and was later replaced by an expansion of Brunn Glass Factory. When Brunn Glass Factory was dismantled, soil and ground water contamination in need of removal had been found in the course of environmental compatibility surveys. These had been mainly caused by residues of tar processing (polycyclic aromatic hydrocarbons/PAC and aliphatic hydrocarbons). After its incorporation into the suspicious area register and further surveys, the site had been declared a contaminated site and had been included into the contaminated site register in May 2012. The owners of the affected properties, Wiener Städtische Versicherung AG Vienna Insurance Group and Pilkington Austria GmbH founded the Brunn N68 Sanierungs GmbH which, in turn, commissioned PORR with rehabilitation work.
The order included the removal and proper disposal of the contaminated subsoil layers protected by a temporary building pit supporting system (sheet-pile wall) with ground water drainage and ground water treatment. At the immediate access to the central rehabilitation area, a white and black plant was used and an open ground water drainage system was installed within the excavation area.
The ground water was extracted from the excavation area by means of pumps via mobile lines and guided to a treatment system. There it was first run through a sedimentation tank, then cleaned by means of a activated carbon filter system and discharged into the channelled recipient under adherence to the limit values of the General Waste Water Emission Directive AAEV (an additional limit value of 100μg/l had been specified for PAK-15). At the same time as rehabilitation measures were underway, old parts and foundation elements belonging to the former roofing felt factory found in the subsoil were demolished and removed. Using a recycling system, non-contaminated excavated material was treated on site in such a way that it met grade II in accordance with the directive for recycled building materials issued by the Austrian Building Material Recycling Association. The broken-up material was used as a building material in the construction site’s area (outside of the ground water fluctuation area). The material used for re-filling was sampled and tested by means of chemical analyses prior to installation. Filling took place layer by layer and was compacted using appropriate equipment.