Award-winning Green Street Library utilising Stratavault for tree pits, water harvesting and storage below the pavement

About the Project

The Green Square Library and Plaza in Sydney, Australia, has turned the idea of a traditional public library literally on its head. With the library located underground, this innovative design allowed for a significant urban plaza to be brought to life at street level. Fusing built form and landscape to create a vibrant ‘urban living room’ with flexible public amenities, the plaza features lemon-scented gums in a verdant open setting.

Internationally-acclaimed design practice, HASSELL, developed the detailed design for the 8,500 sqm urban plaza in collaboration with the library architects, Studio Hollenstein and Stewart Architecture, referencing their winning City of Sydney competition scheme. As the first of several public places to be delivered for the new Green Square Town Centre Precinct – Australia’s largest urban renewal zone and future home to some 30,500 new residents – the City of Sydney wanted the plaza to become a civic heart of the community, enabling a wide variety of casual and programmed uses.

Project Goals

In order for Green Square Library to provide adequate shade for cooling and comfort and to create the desired leafy landscape, introducing and establishing healthy trees was integral to the plaza’s success. However, the provision of large volumes of quality soil beneath the paved forecourt and safely above the library presented a significant engineering challenge.

Citygreen’s Stratavault solution was chosen for its ability to maximise soil volumes while supporting an integrated pavement design that was both easy to install and cost-efficient. Large stormwater storage tanks were also constructed using the Stratavault system, with welded liners and adduction pipe systems incorporated into the structure. This highly-configurable solution enabled irregularly-sized spaces which would typically be wasted to instead be optimised for water harvesting and storage below the pavement. Concerns regarding future access through the pavement were mitigated through the use of a fully-supported structural vault. Strong, flexible and sustainably manufactured using 100% recycled plastic, the Stratavault system delivers both environmental and cost benefits.

Project Vision

Jason Cuffe, Senior Associate at Hassell said, “The public domain has been unified through a hardy and cohesive suite of planting, paving and urban elements that build upon the language of the precinct and reflect the urbanity of the plaza. Multiple rooms of experience are provided within the plaza, each offering a different opportunity – from social gathering to quiet reflection – including an ephemeral water-play feature, grass lawn, green-walled amphitheatre and sunken garden set within the library. All are framed by a ring of lemon-scented gums, offering shade and seasonal character. The design embraces the City of Sydney’s wider sustainability goals for open spaces through water management, green spaces, connections and walkability. The need for potable irrigation has been managed using drought-tolerant plants, unique soil composites, on-site water detention, stormwater harvesting tree pit zones, and overland flow and drainage reticulated within planting zones. And tree pits have been designed to maximise soil volumes, growth rates and overall performance.”

Project Outcome

Citygreen worked closely with Hassell, project engineers ARUP, builder John Holland Group and installer Stone will Landscaping during the design, specification and installation phases. This close working relationship between all parties has resulted in a truly successful outcome – a functional, aesthetically striking and sustainable plaza that has been recognised with multiple awards including:

• 2019 Australian Institute of Architects National Architecture Award for Urban Design
• 2019 Good Design Award – Gold Winner – Architectural Design: Urban Design
• 2019 Australian Institute of Architects (NSW) Awards – Award for Urban Design
• 2019 Australian Institute of Landscape Architects (NSW) Awards – Landscape Architecture Award for Civic Landscape