Pascal Suer

Coal Tar‐Containing Asphalt Resource or Hazardous Waste?

Coal tar was used in Sweden for the production of asphalt and for the drenching of stabilization gravel until 1973. The tar has high concentrations of polycyclic aromatic hydrocarbons (PAH), some of which may be strongly carcinogenic. Approximately 20 million tonnes of tar-containing asphalt is present in the public roads in Sweden. Used asphalt from rebuilding can be classified as hazardous waste according to the Swedish Waste Act. The cost of treating the material removed as hazardous waste can be very high due to the large amount that has to be treated, and the total environmental benefit is unclear. The transport of used asphalt to landfill or combustion will affect other environmental targets. The present project, based on three case studies of road projects in Sweden, evaluates the consequences of four scenarios for handling the material: reuse, landfill, biological treatment, and incineration. The results show that reuse of the coal tar-containing materials in new road construction is the most favorable alternative in terms of cost, material use, land use, energy consumption, and air emissions.

Sustainable decisions on the agenda – a decision support tool and its application on climate-change adaptation

A decision support tool aiming to facilitate discussion and transparency in land-use planning processes has been developed. It includes process steps initiating with an analysis of the current situation, identification of relevant actions and sustainability analysis steps. The sustainability was subdivided into human health and environment, resources, and social and economic impacts. The main difference between this risk analysis tool and others is the allowance of comparisons of present risks and consequences of measures early in the process. It also includes assessments from short- and long-term perspectives, such as taking into account climate change. It combines classic risk analysis with life-cycle assessment procedure. It has been developed and tested in co-operation with municipalities. The tests show that the tool is applicable and can be relevant in the planning process. It offers an iterative discussion framework that is systematic, condensed and yet a simplistic way of describing consequences. The criticism is that it is regarded as time demanding, but this can be managed by preparatory work.

Local Gain, Global Loss: The Environmental Cost of Action

Lower toxicity and less pollution is the goal of all soil remediation. We are willing to spend money and time to achieve this. And our action of treating the soil causes new pollution in its turn.

Ion Exchange as a Cause of Natural Restabilisation of Quick Clay – A Model Study

Quick clay may be stabilised by increased magnesium concentrations in the pore water. Weathering has so far been cited as the source of magnesium, but is an unlikely process at 15 m depth in clays, where an increase was found at a test site in the south of Sweden. This study investigates how far ion exchange can explain the source of magnesium. A rough model in the program PHREEQC incorporating ion exchange, but not weathering, is used to model geochemical and transport processes since the latest ice age in a soil profile in the Gota River valley. Rain water, or rain water with added calcium or magnesium carbonate, is used as infiltrating solution. Calcium or magnesium could come from weathering in the dry crust. Advection, diffusion and ion exchange are sufficient to approximate concentrations in the pore water, if the infiltrating water contains calcium. Weathering at depths below 5 m is not included in the model, but observations of magnesium are reproduced nevertheless. The magnesium comes from the sea water at the end of the latest ice age and has been stored on the ion exchange sites in the clay. The magnesium is displaced into the pore water when calcium enters the soil, is transported downwards, and partly re-enters the exchange sites. The rough model supports the importance of ion exchange for the restabilisation of quick clay by natural magnesium at this site.