Honoured this year among the Royal Architectural Institute of Canada's Awards of Excellence in the Innovation in Architecture category, Borden Park Natural Swimming Pool in Edmonton, Alberta, is the first chemical–free public outdoor pool to be built in Canada.
The 64,000sq ft (19,500sq m) complex, which includes two pools, a sandy beach and changing rooms, was designed by Toronto-based gh3 architecture
Instead of chlorine or other chemicals for disinfection, Borden Park relies on the cleansing capabilities of sand, gravel and a range of aquatic plants and microscopic organisms.
The US$11m (€9.8m, £9m) project was put together with the help of consultants Polyplan
(pool engineering), the German natural pool specialists Morrison Hershfield
(structural, mechanical, electrical, civil and LEED), and BTY
(cost consultants). Polyplan devised the all-important treatment and filtration process that keep the water clean.
Built on the site of a previous pool dating from the 1950s, Borden Park NSP includes some of the original buildings from the 1950s pool, but also features gabion walls made of pieces of local dark limestone that are held together without mortar by being enclosed in wire cages, adding a further thematic nod to the porousness of the filtration process for the water.