Our complex urban environment requires flexible, multifunctional designs that make their surrounding flourish and preferably at the same time decrease expenses in maintenance. By integrating blue, green and grey infrastructure, sharing space and volume in the streetscape, we create multifunctional streetscapes that can handle transport and traffic load (the grey), stormwater and pollution (the blue) and at the same time give the vegetation the space it needs to thrive (the green). The result is a greener and more attractive urban environment with lower risk of flooding and reduced drought stress to vegetation. It’s a step towards a more sustainable city that is better equipped for future challenges. Hard surfaces such as roads, parking lots, walkways and cycle paths are traditionally constructed with a subbase layer that consists of crushed rock with the fraction 0-90 mm. In this conventional subbase roots struggle to grow due to very low permeability and gas exchange and there are no possibilities to use the subbase for storage of stormwater. In BGG-system, the subbase is utilized in a new way. By using crushed rock without the fine fractions (open subbase material) there will be a subbase with large pores that can be filled up with water and air. The open subbase layer (OSL) has a capacity to store up to 400 L of water per cubic meter. Using the OSL as a foundation for the system, we then add other facilities to the design. Depending on the use of the surface, the demands of stormwater quality for the specific site and on the desired design, we install different components which treat the water while leading it down to the OSL. Anything from a permeable pavement or asphalt, a rain garden or a tree trench can be installed. In order to increase the function of the OSL as a substrate for vegetation and a stormwater biofilter we use biochar in the OSL. Microorganisms and plant roots can thrive here, which results in more efficient water treatment, but also healthier vegetation on the streets. The roots that grow into the OSL will form a symbiosis with the microbes. Biochar is made from garden waste, sludge or other organic residues. It improves the conditions for vegetation by retaining and providing nutrients and water. Apart from having a positive effect on the microbial life and vegetation, it improves water treatment and serves as a carbon sink in the town.