One Airport, 52 Walls

By Lindsey O'Connor, Rosetta Hardscapes LLC

Renovations to the Halifax Stanfield International Airport in 2009 included a large-scale landscaping and beautification update, including grass, shrub and tree plantings, and the installation of 52 retaining walls to direct pedestrian traffic and improve the look of a slope outside the terminal.

When the Halifax Stanfield International Airport in Nova Scotia decided to build a new parking garage, they chose to incorporate a major landscaping initiative as well.

A steep grade separated the terminal and the new parking garage, and the landscape architects designing the project needed a way to improve the aesthetics of the slope. The airport also wanted pedestrian flow to be directed in an obvious but inconspicuous way.

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Stone manufacturer Quality Concrete had to rent extra forms and double cast to meet the project's tight deadline. About 8,800 square feet of retaining walls were installed in total.

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The airport's terminal and new parking garage included architectural elements that carried the aerodynamic look of a plane's wing. The landscape architects wanted to integrate those same elements into the new landscape.

"The technical goal of the project was to address a steeply sloping bank in an attractive manner, and to use a product that would be reflective of Nova Scotia's existing natural rock outcrops," said James McKee, principal landscape architect for Vollick McKee Petersmann and Associates Limited.

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Rosetta Outcropping stone was used for the retaining walls, selected by the design team for its flexibility during installation. The designers wanted to place the walls in customized curved and right-angled patterns, so the numerous walls on-site would look like a natural extension of the slope.

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Design
To create the right aesthetic, the designers sought out a stone product that split the difference between natural and functional. "We were looking for a more organic retaining wall product that didn't look manufactured, and didn't look modern," McKee said.

The design team, after extensively laying out the area with CAD, identified locations for a total of 52 separate walls. Installers used stones from the Rosetta Outcropping Collection, in a varied series of angles that pick up on the architectural elements in the airport buildings. The walls throughout the project were installed specifically without straight sections or traditionally curved sections. "We were trying to build retaining walls without them looking like retaining walls," McKee explained.

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The retaining walls became their own theme within the airport complex, underlining the welcome signage with a style that matched Nova Scotia's natural rock outcroppings.

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The stones selected were easily laid in curved or 90-degree cornered patterns. Unique size units and textures gave the architects flexibility to design each wall slightly differently, creating an impression throughout the project that the walls were protruding naturally, as an extension of the slope. By the end of the renovation, the retaining walls had become their own motif within the airport complex, underlining the welcome signage that greets travelers at the entrance to the airport. The design of the walls played well into the aeronautical theme of the airport complex.

"As you drive into the parking garage, the canopy over you is actually shaped like the wing of a plane, even though you don't really notice it. That same theme is repeated throughout the airport so we repeated it in the landscape as well," McKee said.

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Turfgrass was installed along pedestrian walkways, but the retaining walls and raised plantings keep traffic moving in the right direction.

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The landscape architects also achieved their goal of subtly directing pedestrian traffic with the design and placement of the retaining walls. "We used the walls to create planting beds to encourage people to keep off the grass, without pedestrians knowing," McKee said. "If we just had grass, people would be walking across these lawns and going where we didn't want them to go."

Production
Once the designs were in place, production of the project was constrained by very tight schedule. The blocks were manufactured by Quality Concrete and installed by Dexter Construction, at the designer's direction. To deliver the large number of blocks necessary for the project on time, Quality Concrete had to rent extra forms and double cast.

All 52 of the walls on site were designed as gravity structures. The installers excavated the slope to establish leveling pad for the walls. The tallest wall stood approximately four feet tall, but most of the walls were between two and three feet. In total, the project used 8,800 square feet of Outcropping walls, and took about two months to complete.