From landfills to landscapes - nature based solutions for water management taking into account legacy contamination.

Nature based solutions (NBS) can be used in combination with reopening of piped rivers to support area development. In certain cases, piped rivers can run through disused landfills and this presents a complicating factor as the landfills provide the possibility for river water to be contaminated by waste. In Skien municipality close to Oslo, Norway, NBS are being considered as part of a potential reopening of the Kjorbekk stream. A 4 km stretch of the stream is contained in an aging pipe infrastructure that is buried under two disused landfills. The pipe infrastructure does not have the physical capacity to cope with an increase in precipitation that accompanies current climate change, and in certain areas, the pipe has started to leak. This means that surface water run off that cannot be accommodated by the pipe, as well as water that leaks from the pipe can become contaminated by the waste in the disused landfill. The water can furthermore be transported with the stream course to the final recipient, taking the contamination with it. Reopening the stream and providing new water pathways can alleviate these problems, but it must be carried out in such a way that contamination is not spread. This case study shows how certain NBS that focus on reducing the amount of water in contact with pollutants, reducing the amount of particle spreading, remediating contaminated water and remediating contaminated soil, could be implemented at the site and function as a catalyst for an incremental city development. Key Points: The kjorbekk stream runs in an old pipe infrastructure which is unable to accommodate the increase in rainfall predicted via climate change. The pipe runs through two disused landfill sites which were built without bottom membranes and waste in the landfill has the potential to contaminate excess rainfall water that it comes into contact with. Nature based solutions are being considered in combination with reopening of the kjorbekk stream, however they must ensure that the pollutants are not mobilized and do not result in a wider area becoming contaminated. This article is protected by copyright. All rights reserved.