Technology: Housing Rehabilitation after Oil Contermination in Floodplains
- Mark Kammerbauer, Frank Kaltenbach
So-called hundred year floods occur repeatedly in ever shorter intervals. Aside from the visible damage caused by water, an invisible danger often arises that continues to linger even long after buildings have dried out: leaked contaminants that intrude deeply into the construction materials of buildings. Products of the chemical industry, animal carcasses and faeces, and most of all, heating oil spills can make it necessary to rehabilitate entire neighbourhoods or even partially or completely demolish and rebuild them afterwards. June 2013. In the Fischerdorf and Natternberg neighbourhoods of the Lower Bavarian city of Deggendorf at the confluence of the Donau and Isar rivers, the disaster reaches its climax. The levee along the Isar river was not yet complete and another levee situated further upriver breached. The floodwater contaminated with heating oil didn't run off quickly and remained in place for the unusually long period of over a week, causing the contamination of buildings. The residents and authorities had considered this area of the riverine environment, protected by a comprehensive system of levees and ecological restoration measures, as relatively safe. Hardly anyone had expected a coincidence of so many disadvantageous events. In regard to toxic heating oil contamination, an expert report can help to prevent hasty, counterproductive or unnecessary spontaneous remediation and rehabilitation measures. However, many spontaneous helpers on site had already removed up to 11 cm of wall surface and building material. This compromised the structural stability of houses, and both money and energy were wasted. In such serious cases, demolition often became unavoidable. Even after drying out and renovation, oil spots returned to the surface in a number of homes: traces of heating oil that had seeped deeply into the pores of the brick- and blockwork penetrated the new render layers from within (ill. 6).
