YOUR FORUM FOR PLAY, SPORTS UND LEISURE AREAS
Sustainable drainage systems for sports fields are increasingly being used and are relatively easy to implement. The aim is to collect large and small amounts of water, store them temporarily and feed them back into the natural water cycle. For the fundamental challenges of our times are obvious: increasing urban densification calls for de-sealing or, alternatively, a controlled use of water.
Munder and Erzepky Landscape Architects therefore increasingly opt for swale/infiltration trench drainage systems for sports fields and schoolyards. The rainwater seeps away on site with the help of swales and infiltration trenches and slowly soaks into the ground in a targeted manner. This circulation system prevents excessive waterlogging of the subsoil and ensures that a sports field remains functional in the long term. Most recently, the 200 pupils of the Harkshörn optional all-day primary school in Norderstedt were pleased to have a new, colourful and sustainable sports field at their school.
Initial situation
The old sports facility of the primary school in Norderstedt was heavily mossy and its standard red synthetic flooring was regularly torn and in need of repair. This was due to the closely spaced trees around the sports field, which contributed to the wetness and called for intensive maintenance. The city of Norderstedt and the Department of Building Management therefore decided to have the site thoroughly refurbished: ̔We wanted the problems of the old sports field to be investigated and long-term solutions to be found for the new planning, in particular for the drainage. In addition, the entire area was to be colourfully designed and thus become attractive for children and young people,̓ says M. Sc. Aiko Henke, in charge of the new construction and redevelopment of the outdoor facilities in Norderstedt.
Design
The formation of moss and algae was prevented by relocating the football pitch so that it was out of the shade and away from the tree canopy, thus placing it closer to the running track. Extending the pitch at the front, highlighted in yellow, is the long jump runway and sand pit. Parallel to the long side of the pitch, at its old location, a new running track in purple was installed.
In order to decide which drainage system is to be recommended, each plot of land that is to be redeveloped or newly designed as a sports field is examined individually by Munder and Erzepky Landscape Architects. Key criteria are the soil properties, the soil-bearing capacity, the topography, the natural hydraulic gradient or the existing sewer system. For example, clay as the predominant soil material is unsuitable for sustainable rainwater management, as the rainwater seeps away poorly if at all. Soil samples are therefore taken, each of which will affect the design and execution of the construction project.
In the case of the sports field refurbishment at the Harkshörn primary school in Norderstedt, the sampling results suited the project management and landscape architects Johanna Bauer and Wolfram Munder from Munder and Erzepky to such an extent that a sustainable drainage recirculation system could be recommended and provided for.
Implementation
The soil samples also showed that the soil-bearing capacity had to be improved first for this sports field. This was done where it was necessary for the planned synthetic flooring and the future use of various sports, as well as in the area of the paved surfaces.
Following partial soil replacement, the sandy subsoil was compacted with a sheepsfoot roller in several working steps. This special treatment improves the soil-bearing capacity by reaching the deeper layers of the soil. Afterwards, the high-quality bearing course material Hyperdur was used. The various base layers were applied and statically compacted several times.
For rainwater management, two turf areas parallel to the long sides of the pitch have been designed as swales to ensure that the rainwater from the surfaces first runs off into them. At the bottom of the swales are underground "infiltration trenches", i.e. trenches filled with coarse gravel that can initially absorb the water. They also ensure that the accumulated water gradually and systematically infiltrates into the soil. By not draining it, the water is available to the trees on site.
The French word for infiltration trench is “rigole”, meaning channel or ditch. An infiltration trench therefore serves as some kind of buffer storage. As the word has evolved, so have the technical solutions. There are gravel infiltration trenches, box infiltration trenches as plastic chambers or large tunnel infiltration trenches in the form of vaults. The choice depends on the construction project – for a sports field with little to no vehicle traffic, the relatively simple and small gravel infiltration trenches can be used. The size also depends on the expected rainfall.
Additional gravel infiltration trenches have been installed at favourable locations on the sports field to allow the rainwater to infiltrate evenly. Thanks to this targeted control and buffer zones for the rainwater, no additional infiltration pipes are necessary and plastic or synthetic materials can be completely dispensed with in the soil.
In order to be able to cross the grassed swale safely and without barriers, a small bridge made of a prefabricated concrete element has been placed at one end. This bridge provides easy access to both sides of the pitch. The swales and the prefabricated elements were bordered and separated from the pitch by light-coloured paving, which harmonizes perfectly with the light colours of the surface courses.
The colour scheme for the EPDM surface course has been custom-mixed digitally by Polyplace and made available for selection. With green, yellow and purple, it was possible to make the wish of the city of Norderstedt, Department of Building Management, for a colourful and modern sports field for the Harkshörn primary school come true. Classic white was chosen for the pitch and running track line marking in order to create a harmonious and well-balanced overall appearance. The pitch was provided with a football line marking and, in addition, special football goals, the posts of which are filled with sand to reduce the noise level. For the long jump area, red line marking was used to contrast with the sports facility.
Conclusion
The pupils of the Harkshörn optional all-day primary school can now again enjoy varied PE lessons and exciting football matches on the football pitch, on the new sprint running track and in the long jump area. ̔We are very pleased that we were able to implement sustainable rainwater management for this project and hope that this will be possible and requested for more and more construction projects,̓ says project manager Johanna Bauer from Munder and Erzepky Landscape Architects bdla. In September 2022, the sports field was completed at a gross construction cost of approx. 450,000 €. It stands out for its sophisticated and sustainable rainwater management.
