Defence Establishment Orchard Hills (abbreviated as DEOH) is a tri-service munitions storage base of particular importance to the Royal Australian Air Force (RAAF).

[3] Defence Establishment Orchard Hills encompasses a significant area of critically endangered and protected Cumberland Plain Woodland,[4][5] which is endemic to the Western Sydney region.

[6] During siting and construction of the Western Sydney (Nancy Bird-Walton) Airport, it was announced that Defence Establishment Orchard Hills would serve as an environmental offset to compensate for destruction of the woodland associated with clearing of the airport; over 900-hectares of Defence Establishment Orchard Hills was set aside for this purpose.

[8] Other groups have raised concerns that because the property is owned by the Federal Government and was already listed for protection and conservation, it does not serve as an effective offset for the new construction.

The scope presented to the Public Works Committee in 2024 includes:[12] The project is valued at $AUD359.3 million with construction expected to commence in 2025.