AILA projects

New South Wales Projects & Sites

Rouse Hill Landscape Restoration

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Landscape Architect: AECOM

Location: Rouse Hill (Sydney) New South Wales

As listed as A Case Study for the AILA's 2008-2009 National Climate Change Project

Detailed Overview

The Rouse Hill Development Area is located in Sydney's north-west growth sector, approximately 39 kilometres from the Sydney CBD. In what will be a highly urbanised region, the low maintenance riparian restoration of 16 hectares of stormwater infrastructure will manage large stormwater flows, and reinstate endangered ecological communities characteristic of those present prior to European colonisation.

SPECIAL FACTORS

Design of stormwater infrastructure that met all conveyance and storage requirements as well as the capacity to contain fully structured plant communities.

Provision of specialist site soil stripping and reinstatement processes to conserve important existing soil landscape properties and buffer the works from chemically hostile sub-soils.

Creation and monitoring of a one-hectare experimental native grass direct seeding plot to assess the potential of the process to provide a simple and low-cost alternative to initial site stabilisation, weed suppression and conventional mass planting landscape restoration approaches.

Contribution to the stewardship of ecological and/or cultural land systems

AECOM's landscape restoration works on Rouse Hill include bushland reconstruction and regeneration to all areas within the 1-in-100-year flood zone, incorporating channel reconstruction, detention basins and bushland remnants. Most of the works area has been under agricultural management since the early 1800s, and therefore has a very high weed seed load.

The works aim to restore plant associations characteristic of the two endangered ecological communities that inhabited the site prior to European settlement: Cumberland Plain Woodland and River-Flat Eucalypt Forest. All plant material used is of local provenance, with a total of 1.7 million plants installed, comprising some 50 species.

Demonstration of a deep understanding of the science of landscape architecture and founded on robust environmental/cultural land management principles

Our team of environmental specialists, under the leadership of Environmental Director Mark Blanche, guided the design process for detention basins and new watercourses to accommodate floodwaters and fully-structured natural communities, including full ground, shrub and mid-stratum layers and canopy.

A landscape rehabilitation plan prepared at the concept stage of the project ensured design input into engineering works to maximise landscape restoration outcomes.

Demonstration of innovation or establishes new directions in land management best practice

Soil stripping and reinstatement processes

New site soil stripping and reinstatement processes were developed for the project to conserve important existing soil landscape properties and buffer the works from chemically hostile sub-soils. Only site soil was used throughout the project.

Incorporation of experimental design into projects

AECOM facilitated and provided oversight for the incorporation by a specialist contractor of a one-hectare experimental plot to monitor the direct seeding of a select suite of native grasses, to assess the potential of the process to provide a simple and low-cost alternative to initial site stabilisation, weed suppression and conventional mass planting landscape restoration approaches. The results were highly encouraging, with several species exhibiting excellent plant cover, germination of off-spring and weed suppression characteristics.

The approach has the potential to facilitate a new low-cost, longer-term approach to broad acre landscape restoration, in lieu of current mass planting practices. The results of the experiment have been documented and presented as conference proceedings.

Utilising technology to monitor restoration outcomes

Monitoring and reporting on landscape restoration to basins and channels at three-monthly intervals measured outcomes against key restoration goals. Monitoring was undertaken using a field GPS-GIS data collection unit, which quickly and accurately maps key monitoring criteria.

Sharing the knowledge

Training in on-site soil stripping by a specialist soil scientist was provided to all contractors to ensure quality outcomes.

Throughout March and April 2009, over 80 visitors from New South Wales industry and Local and State Government experienced firsthand the positive outcomes that can be achieved through innovative bush restoration techniques, as they attended guided tours by environmental managers and landscape architects from AECOM. The tours proved to be a valuable forum for sharing information about bush restoration techniques and bringing together those involved in similar works.

Effectively responds to, and extends, intention of the brief in land management matters
The project effectively responded to the brief through the provision of a species-rich (approximately 50 species) and relatively low maintenance outcome that conserves local flora gene pools, creates habitat and provides a future ‘natural’ recreation resource within walking distance of thousands of new homes.

The project extended the brief by recommending the implementation of a native grass direct seeding experiment, as described above.

Addresing the AILA Landscape Principles

VALUE OUR LANDSCAPE

Creation of robust plant communities with relatively high species diversity (50 species), all of local provenance.

Reinstatement of pre-existing natural plant communities, including bush regeneration to existing remnants.

Preparation of a landscape rehabilitation plan at the concept stage of the project which ensured design input into engineering works and maximised landscape restoration outcomes (described in the next section).

PROTECT› ENHANCE› REGENERATE

Sizing of detention basins to contain up to the 1-in-100-year flood, in addition to containing fully structured plant communities.

Sizing of channels to convey required flood flows, while also containing fully structured riparian communities.

Specialist soil stripping, stockpiling and reinstatement processes by soil horizon to reinstate the natural soil landscape characteristics, and buffer the bushland restoration works from hostile sub-soil conditions.

Provision of one hectare of compensatory landscape restoration planting (for the direct seeding trial) and one hectare of bush regeneration area offsets unavoidable tree losses, for example, in areas along pipeline routes where trees were not permitted to be reinstated.

Training in on-site soil stripping by a specialist soil scientist was provided to all contractors.

DESIGN WITH RESPECT
The project demonstrates innovative approaches to current socio-cultural, environmental and economic aspects of landscape.

Provision of much-needed landscape reinstatement to areas that have been subject to intensive agricultural activity for well over 100 years and have lost most of their biodiversity.

Creation of a relatively low-cost, low-maintenance, long-term approach to broad-acre landscape restoration that is ecologically resilient and provides a robust landscape that is likely to be provide a ‘best possible’ response to climate change.

Biodiversity is relatively high and the works provide a framework for future augmentation of species, and an on-going building up of biodiversity.

DESIGN FOR THE FUTURE
The project demonstrates creative approaches to building resilience in terms of enhancing socio-cultural, environmental and economic outcomes for future generations.

The created communities are of local provenance and can potentially be expected to provide the greatest possible level of resilience against climate change impacts.

The project is self-regenerating and relatively low maintenance, assisting with long-term economic viability.

The project provides opportunities for community ownership by means of Bush Care and similar types of local interest groups.

The project forms a basis for a future regional open space and environmental corridor, linking the watershed to the catchment outlet point.

EMBRACE RESPONSIVE DESIGN
The project demonstrates innovative, adaptable and responsive design processes; incorporates evaluative frameworks; and enhances potential to adjust to socio-cultural, environmental and economic change.

Facilitation and oversight of the creation and monitoring a one-hectare experimental native grass direct seeding plot assessing the potential of the process to provide a simple and low-cost alternative to initial site stabilisation, weed suppression and conventional mass planting landscape restoration approaches.

Monitoring and reporting on landscape restoration to basins and channels at three-monthly intervals measures outcomes against key restoration goals. Monitoring was undertaken using a field GPS-GIS data collection unit, which quickly and accurately mapped key monitoring criteria.

Regular monitoring of restoration outcomes through the plant establishment period has captured important information on issues such as species diversity, relative performance of individual species, changes in plant density and cover over time, and key weed species of concern – all of which were used to guide the ongoing decision-making process and inform future landscape restoration design.

Promoting environmental best practice through the Landscape Principles: As described above. The project required the implementation of a range of necessarily innovative restoration techniques, derived as a direct response to the conditions of the site.

Exhibiting effective and programmed applied research: The results of the experimental direct seeding plot were documented and presented in conference proceedings.

The incorporation of experimental design into projects, as demonstrated by the experimental seed plot, provides substantial information for the development of innovative approaches to future projects (relatively inexpensively).

The extent to which sustainable ecological and/or cultural principles have been identified and adopted.

The project is founded upon sustainable ecological principles.

Creation of native habitat that is endemic and responsive to the habitat opportunities provided by the stormwater infrastructure.

Almost exclusive re-use of site topsoil (with the exception of the seed bed used for the direct seeding experiment).

Implementation of topsoil stripping and reinstatement process by soil horizon that buffers the restoration planting from chemically hostile subsoils, for example, where detention basins are excavated substantially below existing ground levels.

Creation of long-term, low-maintenance natural communities that are self-regenerating and reduce heat island impacts within otherwise densely urbanised settings.

Relevance to profession of landscape architecture, the public and the education of future practitioners and the wider community

Demonstratively expands the scope of the profession in informative, forward looking & thought provoking ways

The project demonstrates:

Benefits of soil stripping and reinstatement to protect against chemically hostile sub-soil conditions and remove the need for the importation of soils;

Importance of securing site boundaries to weed invasion and physical intrusion;

Need for initially intensive weed management, which then tapers off to very minor levels towards the end of the contract period;

Importance of achieving quick, dense plant cover to resist weed invasion and achieve a relatively self sustaining community within a relatively short plant establishment period (typically never more than two years), suitable for handover to a long-term land manager;

Need to identify core suites of hardy, quickly establishing species that are suitably representative of the desired plant associations;

Capacity of native grasses to quickly take up planting gaps, with successive generations of germination from the initial planting occurring within a two-year plant establishment period;

Importance of regular monitoring through the plant establishment period, including species diversity and relative performance, changes in plant density and cover, and key weed species of concern to guide decision-making processes;

Value of regular photographic monitoring, which, for example, can provide reference dates against which the extent of damage from adverse environmental incidents can be assessed, such as the extent of plant losses incurred due to a major flooding event;

Benefits of incorporating experimental design into projects, which can relatively inexpensively provide substantial information for the development of innovative approaches to future projects; and

Benefits of undertaking a critical review of the project upon completion, to document typical problems and how, with hindsight, these can be overcome in future projects.

Raises the awareness & understanding in the community of environmental/cultural values and processes

The project is a living demonstration of how potentially biodiverse, robust, low-maintenance and visually-compelling natural communities can sit side by side with dense urban development.

The project attracted over 80 visitors during two days of site inspections.

Provides a tangible, successful example of the use and application of environmentally and culturally appropriate land management practices

The detention basins exhibit excellent cover, with strong weed suppression qualities and substantial species diversity. The one-hectare 'direct seeding' experimental plot of native grass species, shows great promise for use as a quick, low-cost alternative to conventional mass planting restoration approaches.

introduction / case-study report / overview / images  / location  / Projects

uploaded June 2010