Edmonton Federal Building: The Centennial Plaza Chooses Silva Cell

A Green Infrastructure Champion

– The Federal Building in Edmonton, Alberta, was unoccupied and lifeless for over two decades (1988–2010). Now, the renovated Art Deco building is occupied, integrated with its newly created plaza space and streetscapes with thriving greenery.

 – A five-year construction renewal project from 2010–2015 included the installation of 3,000 (2X and 3X) Silva Cells supporting the health of 70 trees.

 – As part of the Alberta Legislature grounds overlooking the North Saskatchewan River Valley, the project connects to downtown. It invites a growing number of visitors, downtown employees, and residents to walk, enjoy, and interact with the site’s blue and green amenities and infrastructure.

In the past sixty years, the population of Metro Edmonton, Alberta, has grown from 250,000 to 1,500,000 people. The city has been transforming itself in new economies and abundant activities for all seasons. Following the 2008-2009 recession, the Province of Alberta put forth a four-point plan to position the province for a strong economic recovery. The plan proposed investing in public infrastructure, in this case, the Federal Building, which would directly bring 600 employees to the building and the grounds. Incorporation of Green Infrastructure and a LEED Gold certification was the objective early in the design process. The use of Silva Cell assisted in reaching both design goals.

A Popular Plaza Transformed

In 1958 the 11-story Federal Building was constructed on a one-hectare area within the Alberta Legislature grounds. Thirty years later the building was closed and would remain empty until this renovation.

The Province of Alberta had purchased the Federal Building through an exchange with the federal government, followed by a subsequent commitment to add office space within the Legislature precinct. In 2010 it was decided the Federal Building would be renovated to house offices for provincial and legislative staff, with the addition of underground parking and public open space and streetscapes in place of a surface parking lot. The project demanded an extensive team of consultants led by Kasian Architecture with Moriyama and Teshima Architects, Dialog, and Stantec with the support of numerous specialist expertise consultants. Landscape Architects Moriyama and Teshima and Dialog were primarily responsible for the grounds with the direction to create an inviting, enjoyable public realm of major plaza, gardens, and streetscapes with green infrastructure throughout; just part of the reason that the project earned a LEED gold certification in 2015.

Edmonton Federal Building in 1958. Map with Edmonton pinned.

The Lay of the Land

The Federal Building is one of several buildings within the Alberta Legislature grounds. The design team’s intent was to connect the Federal Building to the other surrounding structures centered on the axial alignment of 108 Street (Capital Boulevard) to the dome of the Legislature Building and downtown. Three of the main elements, 99th Ave, the Bowker Building, and the Federal Building were thoughtfully integrated by the plaza and garden’s green and blue infrastructure.

Rendering from Moriyama & Teshima. Federal Building facing the Bowker Building across Capital Plaza in 2009

The Federal Building Capital Plaza extends from 99th Avenue to the existing pools north of the Legislature Building between the Federal Building and the Bowker and Haultain Buildings. 99th Avenue was renewed with 54 trees. A total of 1,104 m3 of soil was provided in 2X Silva Cells to support their healthy growth.

A new pavilion for the Federal Building was created to address and front the plaza. It “complements the scale, design and materials of the Federal Building.” Adjacent to the new pavilion is a grove of 12 trees supported by 104 m3 of soil in Silva Cells. (See: Image 1.)

Slinger pouring soil into the Silva Cells, before tree planting, August 2012.

In front of the Bowker Building, across from the Federal Building, is a 1,500 m2 garden that evokes all six of Alberta’s eco-zones: Boreal Forest, Rocky Mountains, Foothills, Parkland, Grassland, and Canadian Shield. This area created a forest along the length of the Bowker Building. Wooden and paving stone pathways crisscross the forest creating “nature walks” and quiet space for reflection adjacent the plaza with its water feature attraction. Silva Cells support the wooden walkways while connecting the soil volumes on either side so that the whole area is one continuous soil volume space to support the forest. (See: Image 2.)

Image 1: 12 trees beside the pavilion.

Plaza photo in 2017. Shows the interactive water fountains between the Bowker and Federal Buildings.

Design Decisions

The design team was thoughtful and meticulous about their design. The tree placement, prioritizing soil volume and tree species capable of creating a large canopy, while reinforcing Edmonton’s tradition of boulevard tree planting, has led to a beautiful outcome. Landscape architect, Doug Carlyle with Dialog noted, “As part of the Edmonton Federal Building project for Alberta Infrastructure, the public realm included on-site plazas and gardens and adjoining streetscapes. Along 99th Avenue, as part of Edmonton’s Heritage Trail Promenade, the concept and implementation called for broad walks defined by a double arcade of large-scale canopy trees closely spaced in a grid. Brandon Elm (Ulmus americana ‘Brandon’) were selected for their vase-like canopy habit.”

Photo taken September 2017. Brandon Elm (Ulmus americana) line 99th avenue.

June 2020, along 99th Avenue, tree canopy has increased the shade covering, dramatically.

“The trees on 99th Avenue, in the Plaza and its gardens, have been notable in their growth since their installation in 2014. The incorporation of structural soil cells for healthy root systems has facilitated the required soil mix volumes for tree maturity with integrated aeration, water and drainage. I have personally been struck by their health and vigor over the past several years.”

– Doug Carlyle, FCSLA, RCA, Project Landscape Architect at Dialog.

Image 2: Silva Cells sit below the walkway. Courtesy of Moriyama and Teshima Architects, Tom Arban

Shop drawing, Silva Cells used under walkways and footpaths to support soil and tree root function and vitality.

Design for People in Any Weather Condition

The integrated design team including  Dialog Design ensured that the area would meet the needs of the people and adhere to Edmonton’s open, shared space, and walkability values. Now, there is a stronger pedestrian link to downtown, the river valley, and an extension of the Heritage Trail along 99th Avenue.

On Canada Day, July 1, 2015, the renovated plaza was reopened to the public. That’s not to say that the northernmost metropolis does not need to prep for winter. The plaza is capable of housing a professional-size ice skating and hockey rink for some of Edmonton’s coldest months.

Awards and Highlights:

  • Edmonton Urban Design Award winner for award of excellence in civil design-2016
  • The project achieved LEED Gold certification in 2016 and is dark-sky friendly, a great challenge on such a large site with many building facades that required illumination.
  • The plaza area is illuminated with ‘moonbeam’ style lighting from a series of large-scale columns reducing ongoing energy use.
  • The main access path through the eco-gardens is illuminated by full cutoff LED pedestrian posts, with a strong rhythm that aids in wayfinding.
  • There are allium and sedum on the green roof. In addition, the green roof will aid the trees in acting as a heat island deflection, conserve energy, and improve air quality.
  • Inside the building, the Living Wall (3.4 square foot vertical garden) acts as a biofilter for all who enter the building. It won the 2016 North American cities alive conference interior green wall award of excellence.

The Federal Building project is an excellent example of how Architecture and Landscape Architecture can work together in “Place Making”, each one complementing the other to create a space that is much more than its component parts.
Installation Summary
Number of Silva Cells: 3,000 2X and 3X
Soil Volume Total: 4,719 m3
Number of Trees: 56 along 99th Avenue, 12 in small plaza space.
Type of Project: Integrated trees stormwater, government, plaza
Project Designer: Dialog
Architect: Moriyama & Teshima Architects
Project Contractor: Landtec
Installation Date of Silva Cells: 2012–2013
Project Timeline: 2010–2015