Management Plans
Southern Gateway Alliance recognises the environmental challenges and constraints facing construction of the NPBH. As a commitment to protecting and enhancing the environment, SGA is implementing a number of environmental strategies and initiatives.
A series of Environmental Management Plans have been developed in collaboration with key stakeholders to identify potential impacts and detail management measures for the implementation of the project.
This includes Environmental Management Plans for the following areas:
- vegetation
- rehabilitation and landscape
- dieback and weed management
- topsoil
- surface and foreshore water
- fauna
- European heritage
- Aboriginal heritage
- construction
Some of the environmental initiatives implemented by the Alliance are outlined below:
Drakaea elastica
When Spring flora surveys identified populations of a Declared Rare Flora species known as Drakaea elastica (Glossy-leaved Hamer Orchid) in the northern section of the project, the Alliance attached a high priority to the discovery and sought to minimise the impact on the population and its habitat.
In November 2007, the Alliance was granted approval by the State Government and Commonwealth to collect and transplant whole plants, soil-stored seed and ground tubers from the road reserve. With the assistance of the Alliance, the plants were salvaged by the Botanic Gardens and Parks Authority for research purposes.
Additionally, sections of the alignment have been reviewed and realigned as a result of the discovery to minimise the impact as much as possible.
Cockatoo Nesting Boxes
Under the Fauna Management Plan, it was identified that construction of the NPBH could potentially impact the breeding habitat of the White-tailed Black Cockatoo. Endemic to Western Australia and located in the South West, White-tailed Black Cockatoos require suitable tree hollows to nest and breed.
As a result of these findings, the environment team at SGA invested in purchasing and installing a collection of artificial nesting hollows. Known as Cockatubes, these robust, innovative and functional nesting hollows provide safe and secure habitation for the birds and are discreetly positioned high in tree canopies.
Developed in conjunction with the Department of Environment and Conservation, the Cockatubes are manufactured by the Serpentine-Jarrahdale Land Conservation District Committee.
Relocation of Native Grass Trees
To date, the environmental team has relocated 127 native grass trees (Xanthorrhea preissii) from the clearing zone into the road reserve.
Translocation of the grass trees is a significant environmental achievement due to the volume of the relocations and the age of the trees involved. The average age of the grass trees range between 100 and 150 years.
The relocation process is often labour intensive and generally involves a four step process including trimming, transportation, sourcing suitable alternative environments and planting.
The majority of the transplantations have taken place in the southern section of the project.
Fauna fencing and underpasses
Construction of the NPBH traverses various areas which are known to support both large and small native species including reptiles, small mammals and kangaroos.
To minimise harm, provide safe and secure passage for fauna, and to protect road users, the Alliance propose to strategically install fauna fencing and underpasses throughout the alignment.
In 2005, a detailed investigation was undertaken to determine the frequency, distribution and direction of fauna movements and identify the areas of high concentration of fauna migration. The information collected by this study and from local stakeholders’ expertise is helping to guide decisions regarding the number and locations of fauna underpasses.
Sustainable water sources
Water is a key ingredient of construction activity; it is used to assist with soil compaction and to suppress dust. As a sustainable initiative, the Alliance has used surface water from the Serpentine, Murray and Harvey Rivers and the Mayfield and Peel main drains to supplement or replace scarce groundwater resources where possible.