Jämförelse och utvärdering av kommuners strategier för hantering av dagvattenflöden och medförande föroreningar i kvartersmark.

Stormwater management is necessary to avoid flooding and pollutants that can spread further with the water and damage the environment. The legislation that regulates the management of stormwater can be difficult and complicated to interpret. The purpose of this project was to investigate the strategies and decision materials that exist today regarding municipalities’ stormwater management. That was investigated to understand how the legislation works today, whose responsibility it is to manage stormwater and whether there are any specific emission requirements for pollutants.In order to analyse and evaluate how the management of stormwater works in Swedish municipalities, Gotland, Sundsvall and Gothenburg were selected to be investigated, according to size variation and geographical spread. The stormwater strategies of the three municipalities were examined and their possible choice of measures were compared and evaluated. A theoretical modelling was made to investigate how the choices of measures could have affected the spread of pollutants from a specific area with a specific recipient. The area that was examined was selected by the company and the modelling was made using the tools CAD and StormTac.When the investigation was conducted, it was found that it can be difficult to interpret the regulations that exist. The municipalities' stormwater strategies and their choice of measures to manage pollution discharges would differ between the municipalities. The modelling showed that all choices of pollutant reduction measures would reduce pollutants compared to a situation without any treatment at all. The results also showed that the percentage reduction in pollutants would differ with the different choice of measure. The municipalities' have different pollution requirements in different situations, which makes it difficult to interpret their strategy and choice of measures. Despite this, Gothenburg's choice of method seemed to give the best results in this case.In general, it is difficult to determine which municipality is considered to have the best stormwater strategy. More analysis and information about the area's conditions and the recipient's well-being needs to be taken into account in order to be able to make a decision. This project shows that clearer legislation regarding stormwater management should be introduced in order for all municipalities in Sweden to work towards the same goals and achieve equal results