LST HS112 Risk impact individual water supply — GIS support for small sewers

In an assessment of the risk of impact on individual drinking water wells, the risk is assumed to increase by density between residential buildings. The GIS analysis of density is done by aggregating housing with a maximum distance of 200 metres. The risk increases with the number of dwellings with a maximum distance of 200 metres, see Table 13. Unlike the risk assessment of contiguous settlements in the phosphorus and nitrogen models, there is already a risk at 5 households and with greater distances between dwellings. The purpose of the GIS support is to create conditions at a national level for a reasonable, legally certain and more consistent assessment of the level of protection under Chapter 2, Section 3 of the Environmental Code when examining small sewers. The GIS support consists of maps showing the risk of impact on recipient/exposure point due to load from a drain. The maps have been produced through risk assessments based on the legislator’s instructions on criteria for assessing the high/higher level of protection for the entire surface of Sweden.