RAIC Medal for Innovation in Architecture: Borden Park Natural Swimming Pool

The pavilion for Canada’s first chemical-free outdoor pool features gabion basket stone walls.

Location Borden Park, Edmonton, Alberta

Architect gh3*

Photos gh3*

The Borden Park Natural Swimming Pool is the first chemical-free public outdoor pool to be built in Canada. The project replaces an existing pool and includes a seasonal pavilion and landscaped pool precinct for 400 swimmers.

The challenge was to create a large-scale pool with high-quality water control while also achieving an environmentally healthy and natural filtration process. The design process began with developing a pool technology that cleanses the water through stone, gravel, sand and botanic filtering processes. These processes inspired a materials-oriented concept for the change room facility, in which the gabion basket stone walls visually evoke the idea of filtration.

Hydrobotanic ponds are part of the natural water cleansing process.

Canada’s guidelines for public pools are some of the strictest in the world. To realize the project, the architects needed to take a first-principles, science-based approach to the design challenge. By classifying the project as “recreational waters,” the building permit was issued as a “constructed beach with variances,” and the variances were the pools.

The pool involves a balanced ecosystem where plant materials, microorganisms and nutrients come together within a gravel and sand filtering process. Filtration is achieved in two ways: through a biological-mechanical system with a constructed wetland and gravel filter, and in situ, with zooplankton. It is an unsterilized system, free of chemicals and disinfectants. Isolating membranes contain water as it circulates and is cleansed through a natural process.

On-deck showers are integrated into the flush-surface pool design.

The cleansing takes place at the north end of the pool precinct. On the pool deck, water passes through a sand and stone pond and a planted hydrobotanic pond. Adjacent to these ponds, a granular filter PO4 adsorption unit is enclosed by gabion walls continuous with the change room facility.

In addition to universal change rooms and water filtration infrastructure, the seasonal building houses showers, washrooms and staff areas. The swimming facilities include a children’s pool, a deep pool, on-deck outdoor showers, a sandy beach, picnic areas and spaces for other pool-related recreational activities.

The project’s materiality creates a strong conceptual connection between the technical demands of the pool and the design of the built enclosure and landscape elements. The gabion walls’ dark, locally sourced limestone and steel elements define the enclosure’s vertical dimension as filter-like, breathable, granular and porous. The gabion walls of the low rectilinear building terminate with a lid-like flat roof that frames the tree canopy of the park beyond, and enhances the sensation of open-sky spaciousness within the pool precinct.

The pavilion interiors are fitted with marine-grade plywood surfaces rubbed with black and white paints to expose the wood grain in high contrast.

The pool precinct is defined by a planar landscape where flush-to-surface detailing creates seamless interfaces between the sandy beach, concrete pool perimeter and wood decking.

The elemental form and reductive materials enrich the narrative of bathing in the landscape. The juxtaposition of the constructed elements evokes comparisons with the geology of the North Saskatchewan River and the flat topography of the Prairie lands’ edge.

:: Jury ::  
Richard Henriquez (CM, FRAIC), Sergio Morales (MIRAC), Johanna Hurme (FRAIC)

We have here a clear example in which technical innovation is serving the fabrication of an architecture that ultimately transcends it. As Canada’s first non-chemical pool with a natural water filtration system, the Borden Park Pool embodies the idea of innovation and results in an effortless and subtle architectural outcome. The strength of the simple, yet powerful architecture is beautifully integrated with the biological systems that provide healthy user experiences, both physically and psychologically.

CLIENT City of Edmonton, Robb Heit (Project Manager) | ARCHITECT TEAM Pat Hanson (FRAIC), Raymond Chow (MRAIC), John Mckenna, DaeHee Kim, Joel Di Giacomo, Bernard Jin (MRAIC), Nicholas Callies | STRUCTURAL/MECHANICAL/ELECTRICAL/CIVIL Morrison Hershfield | LANDSCAPE gh3* | INTERIORS gh3* | CONTRACTOR EllisDon | NATURAL POOL CONSULTANT Polyplan | AREA 770 m2 | BUDGET $14.4 M | COMPLETION July 2018