The development of metropolitan Perth is highly dependent on the significant sand resources that are generally restricted to isolated pockets in specific geological units within the metropolitan regions’ Bassendean dune system.
Gaskell Sand Quarry lies within one of these isolated pockets, covering ~571 Ha within the Swan Coastal Plain, surrounded by Banksia woodland, Bush Forever Reserves, as well as the Gnangara Pine Plantation. The process of sand extraction requires clearing of the Banksia woodland vegetation from undulating hill-sites, stripping the topsoil and removing the underlying white and yellow quartz sand horizons constituting 18-40m of the sand profile, thereby reducing the resultant sand profile depth by at least 20m.
A major priority of the company is to restore the post-sand extracted sites with a plant community closely resembling the pre-sand extracted Banksia woodland plant community. As part of the restoration process, Hanson collects their own seed from the surrounding local plant communities before being cleared and the seed is then either propagated into seedlings and/or used for broadcast/direct seeding back onto the rehabilitated areas.
Gaskell Sand Quarry is situated within the northern suburbs of Perth. Being on the remnants of the Swan Coastal Plain, the dune system is very isolated, with the surrounding topography quite flat and much of it cleared for residential and forestry purposes. Current infrastructure projects in the area include the construction of the new Northlink Project and Ellenbrook Tank Project. Site infrastructure such as our Processing plant consists of a washing plant, drying plant, bagging shed and resources laboratory. The quarry also sits on top of the Gnangara Water Mound, making the area a source of priority 1 drinking water for the northern suburbs. Therefore the restrictions on chemical usage, sand extraction depths, water extraction levels and usage make it a very sensitive site to work on.
The Gaskell Sand Quarry is located within the South West Australian floristic region- one of the global biodiversity hotspots. The site is on the Swan Coastal Plain and approximately 1000 plant species occur in the area. The dominant vegetation of the site is Banksia Woodland with Banksia attenuata and Banksia menziesii co-dominant canopy species over a highly diverse shrub and herb layer. Plant families particularly well represented in the vegetation include Proteaceae, Dilleniaceae, Ericaceae, Fabaceae, Rutaceae, Goodeniaceae, Cyperaceae, Stylidiaceae, Asteraceae, Restionaceae and Orchidaceae.
Iconic plants found in the area include Kangaroo-paws (Anigozanthos spp.), Grass –trees (Xanthorrhoea spp.), Woolybushes (Adenanthos spp.) and the vegetation defining Banksias. Iconic animals utilizing habitat in the area include Carnaby’s Black Cockatoo (Calyptorhynchus latirostris), Honey Possum (Tarsipes rostratus) and Western Grey Kangaroo (Macropus fuliginosus).
Ongoing nature projects
Hanson works in conjunction with the Botanical Parks and Garden Authority, also known as Kings Park, who conduct research projects and trials to ensure rehabilitation criteria and best environmental practices are met. The first major research program into Banksia woodland restoration commenced in 1995 at the original Gaskell Avenue site, and through community interest, the managing and restoring of Banksia woodlands has been ongoing due to the funding provided through compliance needs in the resources industry. This has enabled major advances to be made in the science and technology of restoration of Banksia woodlands. Monitoring programs are also set up and conducted on an annual basis, recording data from 1, 3, 5, 10 & 20 year old rehabilitation sites. This is to track the progression of the rehabiliation and if there needs to be any adaptations or changes to certain areas.
Other ongoing projects include:
How science underpins successful restoration outcomes – a Banksia woodland example: The collaborative research program focuses on two key scientific areas of inquiry, (1) seedling recruitment and plant survival, and (2) plant growth and development responses to a reconstructed soil environment.
Are we missing a stage? Using nurse plants to promote banksia woodland restoration- Testing specific interactions among species of multiple functional groups to identify potential positive interactions that can be utilized to improve current restoration practices in banksia woodlands
Research collaborations with the ARC Centre for Mine Site Restoration (CMSR), based at Curtin University.