An evaluation of applying existing bioretention sizing methods to cold climates with snow storage conditions.

Eight of the current sizing and design methods proposed for bioretention facilities were evaluated for rainfall runoff and snow storage volumes for a costal cold climate in Trondheim, Norway. The RECARGA bioretention infiltration model was used to compare the performance of the methods using 30 months of observed data from a pilot scale bioretention box. The surface areas, total ponding time, number and duration of overflow events, and snow storage volumes were compared. It was found that even in a costal cold climate with several intermittent melt cycles die snow storage requirements were an important design parameter, and if more than 25% of the total snow volume should stored this became the deciding design parameter.