Innovative Stormwater Management at Allmendstrasse, Zug

With the redevelopment of Allmendstrasse in Zug, swale borders and an avenue of trees were created despite the fact that, according to a geological report, the soil was not suitable for infiltration. The rainwater is channelled over the shoulder into the communicating retention/infiltration troughs. The built-in seepage pipe, which is interrupted by a closed pipe in the area of the trees, enables exchange between the troughs and provides additional storage volume. An emergency overflow, which is currently still connected to the combined wastewater pipe, is located every 30 metres at street level. With the definitive conversion of the Herti neighbourhood to a separate system, the combined wastewater pipe will be converted into a rainwater pipe.

The adjacent car parks at the sports stadiums are constructed with heavy-duty ecoblocks. This allows rainwater to seep into the subsoil over a large area. The remaining rainwater is channelled into the infiltration trough via a uniform gradient. The cleaning efficiency of the infiltration trench is better than conventional drainage with a sludge collector. If water is nevertheless fed into the receiving watercourse during a rain event, it is of significantly better quality.

Measures to reduce rainwater runoff:

• Extensive infiltration in the car park areas
• Infiltration system: Infiltration trough
• Retention
• Evaporation: Tree avenue, minimal from the car parks

Multiple use:

• Rainwater utilisation: Irrigation of the tree avenue
• Heat reduction
• Promotion of biodiversity

The project has been completed and is working. Good results were achieved during heavy rainfall. The infiltration of road runoff via the trough infiltration system reduces peak flows and limits the hydraulic load on the receiving watercourses. The trees are developing very well.

Specifically, Gruner was responsible for the following services as part of the project:

• Development of the construction and implementation project
• Implementation planning with site management and construction accounting
• Detailed planning of the "Weststrasse" concrete roundabout
• Construction management of mechanised concrete roundabout construction in a tight time frame with total closures at weekends and corresponding large-scale traffic diversions
• Renewal of all surfaces with consideration of inner-city requirements from complex pedestrian and traffic routing ("Bossard Arena" station and shopping centre)
• Implementation of redesigned streets and car parks and corresponding planting concept
• Realisation of new lighting concept with associated cable conduit system
• Detailed schedule and cost monitoring

Further information can be found on Allmendstrasse Zug - Schwammstadt information platform (sponge-city.info)

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