GIS Investigation of Potential Offset Properties for Gateway WA

 

 

 

 

Main Roads Western Australia

The Perth Airport and Freight Access Project (Gateway WA) involves improving the road network into and around the Perth Airport prior to the consolidation of the international and domestic terminals in 2017. The road network around the airport is already at capacity during peak periods, and the consolidation of the airport terminals without a major upgrade to the road network will result in significant congestion and failure of the road network.

Gateway WA will involve the upgrade of Tonkin Highway between Great Eastern Highway and Roe Highway including upgrades to the intersections/interchanges at Boud Avenue, Leach Highway, Horrie Miller Drive, Abernethy Road and Roe Highway, an upgrade of Leach Highway between Orrong Road and Tonkin Highway and provide a new access to the consolidated airport terminal from the Tonkin/Leach interchange.

 Area of Management

The proposed ultimate extent of Gateway WA involves some 220 hectares, with approximately 70 hectares of native vegetation to be cleared. MRWA recognise that an offset package is required for Gateway WA, as even after avoiding, minimising, rectifying and reducing impacts, along with proactive environmental management practices, there will be residual impacts on significant environmental values.

360 Environmental Pty Ltd (360 Environmental) was engaged by Main Roads to identify potential environmental offset properties for the project through the use of GIS constraints mapping using the following methodology:

• Identified vegetation complexes in (and around) the clearing areas within the Southern River Complex and Bassendean Complex Central and South.
• Identified vegetation complexes in (and around) the clearing areas within the Southern River Complex and Bassendean Complex Central and South.
• Like-for-like areas were identified (consistent with EPA Policy) for Crown lots considering:
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    • Soil types
    • Southern River Complex and Bassendean Complex Central and South complexes
    • Conservation category wetlands
• Areas designated Bush Forever or already protected by DEC were removed.
• Properties were required to be a minimum of 50 hectares (ha) in size (with the aim of a 200 ha offset).
• Lots without rehabilitation potential were removed i.e those containing urban infrastructure or completely cleared (no remnant native vegetation)
• Lots were required to be within 50 km of the clearing area.

The above methodology was repeated for private land holdings within a 20 km radius of Gateway WA.  Figure 1 shows the offset analysis procedure for Crown and government-owned Lots and Figure 5 for freehold lots. 

Outcomes

Forty Crown lots were identified as potential offset sites and six lots were identified as potential offsets under the freehold search. In refining the recommendations, a small number of offset properties were highlighted as the sites with the most potential to fulfil the obligations of the offset.

Contact

Email: admin@360environmental.com.au

Telephone: +61 8 9388 8360