33 Parallel Landscape Architects assisted CPBUI Contractors and Aspect Studios with the landscape restoration of the the enabling works package for the Western Sydney Airport Metro works between Orchard Hills and Western Sydney Airport. Approximately 10.6km of elevated viaducts and rail batters set on the gently undulating landscape of the Cumberland Plain. The SCAW landscape design sought to minimise ‘hard engineering’ elements and enable opportunities for natural systems to flourish, provide habitat and enhance biodiversity. This approach is expressed in design innovations that have been implemented since the tender design including:
• The design evolution of six steep concrete and rock abutments into gentle 3(H):1(V) vegetated abutment slopes.
• An alternative topsoil strategy that conserves the endemic soil seed bank (Bushland Topsoils).
• Drainage from the viaduct used to passively irrigate the rain shadow under the viaduct.
• Encouraging soil microflora with site waste and replacing imported chemical fertilisers with organic fertilisers made in Australia from composted food waste.
The concrete abutments were changed to vegetated slopes during design development with stormwater from the viaduct directed via exfiltration pipes to the rain shadow under the viaduct to passively irrigate the vegetation. Image by Aspect Studios.
Grevillea juniperina subsp. juniperina, a threatened species occurred on the site. Plants are killed by fire with regeneration solely from soil-stored seed, highlighting the need for a strategy for conserving the endemic soil seed bank.