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PCB and Lindane clean-up operation – Old Town Hall in Regensburg

Principal: Regensburg
Advice zone: Harmful substances in buildings
Customergroup: Local authorities, Real estate
Contact Detlev Michler
T +49 94 14 63 06 16

The Old Town Hall (Altes Rathaus) in Regensburg is a historic building, sections of which date back to between the 11th century and the middle of the 13th century. The building gained historic importance as the seat of the “everlasting Imperial Diet”, a parliament or meeting of the representatives of the Three Estates in the Holy Roman Empire summoned by the Emperor. The east and the north wings of the Town Hall date back to the 17th century and the south wing dates back to the 18th century. Since 1995 indoor pollution measurements have been carried out in the east and north wing rooms, which are mainly used as offices and conference rooms by the council. The results indicated that in the past the wooden structure had been treated with wood preservatives now recognized as a health hazard. The wood preservative substances Pentachlorphenol (PCP), Lindane (y-HCH) and Dichlorfluamide (DCG) were detected in the building structures and in the room air. In the years 2008 – 2011, under the responsibility of Tauw GmbH Regensburg, sample restorations were carried out in six rooms and subsequently a step-by-step restoration of another 15 rooms.

Tauw detected both primary and secondary contamination of building materials in the Altes Rathaus: Firstly, there were items such as wood finish, wall rendering and ceiling plaster which had been directly treated with wood preservative or had been affected by chemical substances. Secondly, there were wooden parquet floors which had taken up contaminants from the harmful substances in the indoor air. The removal of contaminants took place in various stages and while the Rathaus was actively being used: this required careful planning to make sure the building could be used by the staff and remain accessible to tourists. Within the framework of this project Tauw took control of consultancy activities as well as project management and coordination. In addition to systematically cordoning off and making workspaces safe, the health and safety regulations had to be observed. An essential element to guarantee the success of the clean-up activities was to minimize dust production and to generally avoid dust formation as much as possible. Therefore, before commencing the dismantling and renovation work all the building materials, as well as all workspaces, had to be continuously cleaned or vacuumed using vacuum cleaners fitted with special filters. Then the sand bed which had been poured in between the floor joists was removed by means of suction hoses connected to a vacuum pump. The extracted sand was separated in a collecting hopper mounted before the vacuum pump and fitted with additional filters (filter-separator/cloth filter). The removed sand was poured directly into dust-free bags via the collecting hopper. A special coating system (masking) was employed to carry out the restoration of the wooden beams in the suspended ceilings, creating an effective and permanent barrier to the existing harmful substances. When the sub-floor between the floor joists was rebuilt modern building materials (chipboards, mineral dry filling, mineral wool) were used as supporting structure, filling or insulation that meet the modern requirements for fire protection and sound proofing.