Amazon.com leverages Stratacells in new Seattle headquarters
by Sally Cameron
Electronic commerce and cloud computing company, Amazon.com, has leveraged Citygreen’s cutting-edge Stratacell system in its new multi-million office headquarters in South Lake Union, Seattle. Purpose-built to accommodate 20,000 employees, the new headquarters consists of multiple buildings surrounded by mingling areas and plazas.
One plaza, located between two buildings on 6th Avenue, has been constructed above a parking structure, and is home to several feature trees (Cercidiphyllum japonicum and Magnolia laevifolia) which required large planting areas.
Engineering plans allowed enough soil volume beneath the plaza to house the trees, but a significant challenge emerged – how to provide sufficient structural support to cope with the weight of heavy vehicles such as a boom lift, to be used for maintenance. Soil cells were identified as an ideal solution, however many products were rejected because they lacked the structural strength required.
Natalie Ross, Landscape Architect at Site Workshop, said, “Amazon wanted to support soil volume for large trees in the plaza while still allowing maintenance vehicle access. Our challenge was to create a suspended paving area over structure with heavy loading requirements. We also needed to use a non-standard base course because we were over waterproofing which could be crushed or damaged by a traditional gravel base.”
Ross said, “We chose to use Stratacells for their loading capability”, with Citygreen’s 60-series Stratacell system fulfilling the strength requirements. Citygreen worked directly with the consulting landscape architect – Site Workshop of Seattle – to design the structural elements of the plaza. This consists of 500 Stratacells, supported by a concrete slab, a drain-mat, and another slab above. Citygreen provided plan views of the installation to calculate the quantity of cells required, and to show how the slab would be supported. Construction was completed by Pacific Earthworks.
Site Workshop, along with the project architect NBBJ, are very happy with the solution, making particular note of how quickly the cells went together and how easy it was to thread the drip irrigation through the structure. The outcome is a successful mix of hardscape and planting, accommodating both Amazon employees and visitors.
Ross said, “We’re holding up a beautiful granite paved plaza and supporting a large soil volume for trees in a harsh urban environment. The main benefit of Citygreen was their ability to work with their own structural engineers to guarantee their product under heavy loading conditions.”