#bluegreengrey systems at Vårdsätravägen, Rosendal
It includes a continuous strip of open subbase layer that is the foundation for BGG system which cleans and retains stormwater, supports vegetation and simultaneously allows for traffic loads and flexible design.
The open subbase layer in a BGG system is comprised of aggregate which has had the smaller fractions sieved away, thereby creating voids that water and air can flow through. These voids give the material a porosity of 30-40%, allowing storage of up to 400 liters of water per cubic meter of open subbase layer. Since the pores are larger than with conventional fill materials, BGG systems have high hydraulic conductivity for water and gas exchange. This creates the possibility of controlling water flow within the system and discharging it to the conventional sewer system in a controlled manner.
During light rain, the water flows into raingardens where it retains, cleanses and percolates into open subbase layer. During heavy rain raingardens retention capacity can get filled quickly. In such situation overflow can enter stormwater pit that directs stormwater directly into open subbase layer that provides generous space for such volumes.
The street provides retenion capacity for 360 m3 of water. The open subbase layer is connected to additional constructions at ground level like tree trenches, plant beds and hard surfaces for parking bikes and cars.