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The chemical factory of Eugen de Haën was located in the List district of Hanover from 1861 to 1902. Products for photochemistry, pharmacy, electroplating and dyeing were produced there. The resources used included radioactive materials (uranium and thorium ores) as well as various chemicals and elements.
In the course of numerous investigations by various specialist offices, a number of sites were located where radiologically contaminated production waste had been deposited.
Contaminated areas were remediated depending on the risk to human health and/or groundwater.
Due to hundreds of years of urban development in the List district, not all contaminated soil layers can be "reached" equally by a remediation measure. Some areas have been built over by multi-storey residential buildings or are firmly sealed.
To identify soil contamination by the radioactive component from decay series of compounds containing thorium and uranium, measurements of the local dose conduction are carried out at the ground surface. The results of the most recent precautionary investigations are published on the homepage of the City of Hannover: Precautionary radiological investigations of city-owned land | Contaminated Sites Programme | Waste & Soil Protection | Environment | Living in the Hannover Region
If the measured local dose rate exceeds a value of 150 nSv/h at the height of 1 m above the ground surface, it is interpreted as an indication of contamination of the subsurface by the operational waste of the Eugen de Haën chemical factory.
In the course of the investigations already carried out, such suspected areas were located and mapped. All construction measures planned and carried out in the area of the "De Haën" suspected contaminated sites must be accompanied by technical measurements and expert reports so that the concerns of occupational safety and recycling management can be taken into account.
The disposal of the excavated material, which shows both a clear chemical contamination and a contamination in the sense of the StrSchV, requires both increased organisational effort and increased costs for analysis in accordance with waste and radiation protection law.
M&P Nord in Hanover plans, accompanies and advises both the public sector and the implementing companies and authorities in the implementation of small and large construction measures in the area of suspected sites with radioactive soil contamination.
The footage was taken in the course of repairing a downpipe on behalf of the local utility. In the process, almost 20 m³ of radioactively contaminated soil material accumulated.