The treatment effect of wet ponds, wetlands, sedimentation basins and underground sedimentation basins is affected, among other things, by the parameter Hydraulic efficiency. The parameter is now calculated from Thackston’s equation (Thackston et al., 1987; Stockholms stad, 2017). It is reported as before in the result report.

The effect of the treatment effect on the hydraulic efficiency has also been changed by a revised calculated factor that depends on the length:width ratio. As before, it is based on data from Vikström et al. (2011) but is now calculated on the basis of the updated calculated hydraulic efficiency and from more detailed functions between hydraulic efficiency and treatment effect.

The treatment effect of inlet drain filters is also updated as a result of obtained supplementary measurement data, presented in the database.