Chemical-Free Swimming: Borden Park Natural Pool in Edmonton

The natural outdoor pool, which was planned by the gh3* architecture studio, is located in Borden Park, not far from the North Saskatchewan River. To the north, facing the parking lot, a long, single-storey building delimits the grounds of the pool complex. This tract includes not only the entrance, dressing rooms, staff rooms and technical spaces, but also creates a privacy screen for the open-air pools behind it: a large swimming pool and a smaller basin for children. With sand on the ground, the outdoor area is laid out like a beach on which the pools, which are of concrete, lie like an island. Wooden decks lead to the showers and the reception building: the sand offers space for sunbathing and a volleyball court. Inspired by the mechanical filtration process, the architects from gh3* have employed gabion walls as a defining design element: the wire cages filled with dark-coloured rubble stones form the outdoor layer of the exterior walls and are interrupted only by ceiling-high steel doors.   

The natural water purification functions as follows: in a separate pond filled with 2.5 m of sand and gravel, the unclean water is distributed via nozzles over the surface, some of which is planted, and then seeps downwards. In the mechanical filtration process, suspended particles are removed. At the same time, the biofilm found on the surface of the individual gravel stones binds with algae and microorganisms. In two planted ponds, the water is purified further. As needed, the water undergoes phosphate filtration in the technical room, where it is tested for quality as well. As the cleanliness standards for swimming pools are very high in Canada, the architects from gh3* named their project “recreational waters”; the authorities approved the plan as a “built beach with deviations”. For users, the assignation is most likely of no importance.

An in-depth essay on the topic of swimming pools is featured in Detail 9.2021.