New South Wales Sites
Sydney
Olympic Park, Homebush Bay, Sydney
artilce published Landscape Australia no 22 (3- 2000)
New Habitat for Green and Golden Bell Frog Brick Pit
by Mark Blanche
Pittendrigh Shinkfield and Bruce was commissioned by the Olympic Co-ordination Authority (OCA) to create new habitat for the Green and Golden Bell Frog in the Brick Pit at Homebush Bay.
Pittendrigh Shinkfield and Bruce was commissioned by the Olympic Co-ordination Authority (OCA) to undertake the detail design, documentation and periodic inspection for the construction of replacement habitat for the Green and Golden Bell Frog (Litoria aurea) (the Frog) in the Brick Pit at Homebush Bay'.
The Frog is listed on Schedule 1 of the Threatened Species Conservation Acl 1995 as an endangered species in New South Wales. The works were carried out in close association with expert ecologists from Australian Museum Business Services (AMBS) engaged by the OCA, and with OCA staff.
Reason for the Works
The works were required, as the two deepest sections of the Brick Pit were being flooded to provide a reservoir for the Homebush Bay Water Reclamation and Management System (WRAMS). The WRAMS will reclaim sewage and other liquid waste streams from Sydney Olympic Park and the Athlete's Village, for reuse and irrigation within the Homebush Bay site.
Prime Frog habitat was located on the quarry floor within the area proposed for the reservoir, and had to be replaced as part of the OCAs ESD commitment. The OCAs decision to locate the reservoir within the Brick Pit followed five years of intensive study of the Frog, close consultation with expert herpetologists, and widespread review of the project by regulatory bodies, environmental groups and the community.
Design Objectives
The primary objective of these works was to create replacement Frog habitat, situated within the upper levels of the Brick Pit, that was of at least equal area and quality to those areas lost. The design of this habitat had to meet both the requirements of OCA and a Frog Management Plan prepared by AMBS.
The design of the habitat replacement types was experimental, literally seeking to replicate existing successful habitat types within the Brick Pit, in a variety of combinations and locations. Additionally, the Frog is known to be well adapted to colonising highly disturbed sites. A major aim of the design therefore was to maintain this disturbed character. All designs were subject to scientific review by a committee of expert herpetologists.
As far as possible, works sought to utilise only in situ materials, including the relocation of 5 000 tonnes of sandstone boulders from the reservoir floor for habitat creation, and the excavation of some 1,800 tonnes of rock. Where it was necessary to import materials, this was done sparingly, e.g. in the instance of some 4,000 m2 of native grassland planted, minimal organic admix was used to maintain a spartan 'disturbed site' coverage. No fertiliser was used in the project.
'The original concept design was undertaken by HASSELL
in close association with Australian Museum Business Services and the OCA.
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View looking across a major habitat replacement zone showing various habitat types, including deep and shallow open water, shale basking mounds, boulder shelter piles and grassland plantings. `Natural' wetlands are seen in the background (Photo courtesy: Sarah Mason).
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The major `turkey's nest' open water pond, with boulder shelter edging and sporadic low grass/shrub planting (Photo courtesy: Sarah Mason).
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Detail of Frog habitat replacement showing (starting from foreground) macrophyte edge, ephemeral sandstone gravel zone, grassland treatment and both boulder shelter and sandstone rubble basking piles (Photo courtesy: Sarah Mason).
Summary of the Works
The works comprise nineteen ponds with a total volume of 1.1 megalitres (approximate Olympic pool volume) and adjacent terrestrial habitat. This includes deep and shallow ponds (both open water and with macrophyte beds), with combinations of ephemeral gravel zone, macrophyte and boulder refuge edge treatments.
Adjoining areas contain ephemeral soaks, rubble mounds and native grasslands, to provide refuge, foraging and basking areas for the Frog and connect major habitat zones. All of the ponds were lined with a purpose-made bentonite-impregnated geofabric pond liner and 300 nrm clay lining, overlain in places with sandstone rubble.
Outcomes
The new ponds are near completion. Two of these have already experienced very successful breeding events, in spite of a poor breeding season experienced by the Frog throughout the State.
Additionally, due to the diligence of both the landscape contractor and AMBS staff, the high potential for a downturn in the Frog population as a result of carrying out the works did not eventuate. The ponds have been enthusiastically received by both the OCA and AMBS. A significant test of the success of the works will be next season's breeding results (September to May).
2000 International Banksia Award
The work of conserving the Green and Golden Bell Frog at Homebush Bay (of which the habitat replacement works comprised an important component) has recently been recognised by winning both the 2000 Banksia Gold Award and the 2000 Banksia Award in the category of Flora and Fauna Conservation. The Gold Banksia Award is the most prestigious of the Banksia Awards presented each year, and acknowledges individuals or organisations who have made a significant contribution for the betterment of the environment at a global level.
Relevance of the Project
As shown by its recent Banksia Award success, the project has great relevance to both the profession and the wider international community This is due to the way it has successfully demonstrated a management approach that integrates a large, highly complex development, with a scientifically verified, ecologically sustainable outcome. In particular, the project was an excellent example of a 'hand-in-glove' collaboration between the scientific community and the landscape profession.
Client
Olympic Co-ordination Authority
Landscape Architects: Principal Consultant: Pittendrigh, Shinkfield and Bruce
