Closing the Circle

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Updated: November 27, 2018
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Recycling has been seen as a sustainable part of the design and construction of landscapes for more than a decade now as the emphasis on environmental sustainability has gone mainstream.

Recycling is not just a philosophical discussion had by tree-hugging hipsters wanting to save the planet one recyclable coffee cup at a time. When landscapers talk recycling it’s about scale.

Apart from the obvious materials that have long been used in landscapes – recycled materials such as timbers, masonry and aggregates – there are many other options for recycled materials that won’t necessarily give the impression of being second hand, which is a common criticism of the use of recycled products. Many products that have been recycled or repurposed may not even form part of the visual landscape to a great extent. This is evident when it comes to growing media substrates derived from recycled materials.

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Getting Down And Dirty

The use of recycled organics in growing media continues to grow as recycled organic materials in landscapes such as composts, soil conditioners and mulches, soils for landscaping, garden use, potting mixes, and organic products used for playground resurfacing are readily available from suppliers Australia wide. It is advisable to ensure that such products are sourced in accordance with the relevant Australian Standards. Companies such as Australian Native Landscapes and Soilco have made significant inroads in the quality and diversity of recycled organic products available to the landscape industry. The emphasis of recycled products is on quality, ensuring that products are fit for purpose. The processing of urban organics, food waste and timber materials is composted by open windrow composting techniques in accordance with AS4454-2012 (Composts, Soil Conditioners and Mulches) according to Australian Standard certified best practice management.

Waste from the kerbside collection of household waste, away from home collection, and hard waste collection, predominantly consists of putrescible materials such as paper, garden and kitchen waste, process control systems regulate the production of products containing source separated organics. This ensures that best management practices are adopted, and all measures are taken to minimise risks. By following these procedures, products of consistently high quality can be produced.

Recycled Organics Case Study

The use of recycled organics in growing media has often been met with scepticism by many with uninformed views based on misinformation about the performance of recycled organics in growing media. The most common misconception is that product is not uniform and therefore yields variable results.

Showcasing just how wrong some opinions can be is Willinga Park on the NSW South Coast. This 41-hectare horse agistment and training facility with approximately 15 hectares of show gardens was constructed with recycled organic growing media. The native gardens at Willinga Park have been developed on remnant degraded grazing country. Five hectares of gardens were created in 2010 and there have been in excess of 8000 trees, shrubs and plants incorporated into the property. The plantings in the gardens are mainly Australian natives, some endemic to the area. The second garden was constructed in 2016 to showcase the horse dressage arena. Chosen plants are ornamental and were selected for their foliage; this area of the property was completed in 2017.

The gardens required a fit for purpose quality blend that could be used in all areas and suit a variety of native and ornamental species. The stage 1 garden included endemic and native plants such as Banksias and Grevilleas and the show area contains pants that include transplanted Livistonas, Zanthorrhoea glauca, Cascade Palms and Cordyline rubra.

The sheer scale of this project and its success validates the use of recycled organic products in growing media with over 4000m3 of landscape mix and 2100 tonnes of a specialist turf mix utilised in the landscape.

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Hidden Attractions

Whilst aesthetics are an important element of any landscape, the use of recycled materials does not mean there is a compromise to the overall effect and appearance of the landscape. This is very evident in the construction of Barangaroo, Darling Harbour Sydney, where more than 10,000 sandstone blocks were used during construction of the Barangaroo reserve, with 93 per cent excavated from the reserve. 6500 sandstone blocks now line the harbour foreshore at Barangaroo reserve, which incorporates over 75,000 native trees and shrubs.

Excavation took one year with all off-cuts ground down for use in the sandy top soil mixture for the native plantings incorporated on the headland. SESL Australia designed the landscape soil for Barangaroo using almost completely recycled resources. SESL scientists developed a reconstructed soil profile utilising crushed sandstone originating from building excavations in Barangaroo South commercial development, recycled sand from building excavations, recycled green garden waste compost derived from recycled urban organics and composted wood mulch screened from green garden waste collections. Crushed recycled glass was also used as a component in the development of the Barangaroo ‘soil’ profile.

Taking recycling to a whole new level, beneath Barangaroo Reserve is the cutaway cultural space and two levels of car parks and beneath all of this is a leading-edge water reuse system for the capture, storage and reuse of rainwater for the irrigation of the reserve. The two tanks beneath the recreated headland are an enormous 1200m3 rainwater tank and 180m3 seepage tank.

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Growing Greener

Apart from the obvious recyclable materials from construction sites and developments, there are also opportunities to recycle plant material. It is crucial to know what trees and shrubs have resale value and are capable of surviving transplanting, particularly when dealing with mature species. There are some species that will always be in demand especially when it comes to providing scale to a new landscape, but there are many plant species that are better off being repurposed as wood chip.

Specialist tree transplanters can provide professional advice on individual plant suitability for relocation and plant preparation requirements. Reuse of plants no matter what size should always be considered prior to assigning them to the chainsaw.

Setting the Standard

Landscapes constructed with reused or repurposed materials are not limited to large-scale applications. Smaller residential installations can utilise recycled or repurposed products just as affectively. Opportunity also exists for the reclamation and reuse of site materials within any size construction site with thoughtful planning prior to site excavation and demolition activities. Effective incorporation of reused, recycled or repurposed materials in landscapes requires considered planning and an integrated approach to landscape design with collaboration between designers, suppliers and construction contractors to encourage adaptive resource management across all sectors of the landscape construction industry. The use of recycled, reused and repurposed materials in construction

is opening the path to setting a new standard for sustainable ecological landscape design.