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Sponge City

The ACO sponge city concepts based on the Stockholm system

The sponge city principle of the Stockholm system describes an innovative construction method that creates an optimal habitat for large-crowned urban trees, while providing retention space for rainwater. The Stockholm system provides a large volume of root space for the tree to use without damaging the infrastructure above. Stockholm, where this construction method was developed over 20 years ago, has played a pioneering role.

The functional principle


The underground body of the Sponge City consists of coarse aggregate and a special tree substrate. The coarse aggregate provides a robust skeletal structure that ensures the necessary load transfer in accordance with the technical requirements of road construction. The tree substrate forms a permeable pore system in the interstices to supply the tree roots according to their biological requirements. The ACO Sponge City Road Drain ensures a targeted supply of water and air. Excess water can either infiltrate into the groundwater or be drained away in a controlled manner to prevent waterlogging of the roots. In this way, the natural properties of the soil are reproduced and combined with the technical requirements of a road sub-base.

Christopher Peiritsch

“As Confucius said: ‘Take care of the roots - then the branches and leaves can take care of themselves‘!”

Christopher Peiritsch
ACO Green City Expert, ACO Austria

ACO Sponge City Road Drain

With the new Sponge City road drain, ACO, as an expert in rainwater management, offers an effective and easy-to-implement solution for the blue-green transformation of cities. The proven ACO Combipoint street drain system has been extended to include selected Sponge City components, so that rainwater can be fed into the Sponge City body close to the surface for effective irrigation of urban greenery.

  • Preventing heavy rain with permeable sponge urban structures
  • Salt free irrigation solution with simple summer/winter operation
For more info please contact our experts
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