For the revision of the DWA Standard DWA-A 138 approaches of various industrial countries (Great Britain, USA, Australia and Switzerland) have been compared for the dimensioning of percolation facilities. With this, in part large differences, in particular in the procedure with regard to dimensioning frequency, design rainfall, safety factors and calculation of the runoff development, were determined. Other than with German rules and standards there is everywhere a definition with which method the infiltration rate has to be determined. This could, in the future, also find entry into the revised DWA-A 138, combined with a recommended correction factor, which is determined through the method of dimensioning, the variability of the soil conditions and the operation. Thus the approach of the dimensioning using the halving of the coefficient of permeability (kf/2) could, in the future, be given up.     «

For the revision of the DWA Standard DWA-A 138 approaches of various industrial countries (Great Britain, USA, Australia and Switzerland) have been compared for the dimensioning of percolation facilities. With this, in part large differences, in particular in the procedure with regard to dimensioning frequency, design rainfall, safety factors and calculation of the runoff development, were determined. Other than with German rules and standards there is everywhere a definition with which m...     »