Sustainable Sites Initiative

Syrinx Environmental PL: Point Fraser Development (Western Australia)

Point Fraser Precinct Development

Size & Type of Project:
15.14 acres (Stage One: 5.75 acres; Stage Two: 9.39 acres)/ Public Open Space | Reserve; Former brownfield

Location:
Swan River Foreshore, Perth, Western Australia

Budget:
$8.6 million (AUD $9 million) - Total Site Costs

Project Phase:

Point Fraser's staged redevelopment of this site commenced in 2003 and is ongoing. 

• Stage 1: Wetland - Construction completed in June 2005
  
• Stage 2: Under construction - scheduled for completion in 2006
  
• Stage 2B: Scheduled for completion early 2007

Project Overview

Point Fraser Reserve, a significant redevelopment in the Perth Central Business District, is constructed on a previously undeveloped area of reclaimed river foreshore with the aim of improving the health of the Swan River and connecting the city to the water's edge.  The previous use of the Brownfield site was predominantly a carpark and helicoptor pad, with the foreshore area being hard-walled. The former site was underutilized and although prime foreshore land, offered little or no potential interaction with the public domain.  The site's contamination relates to being affected by Acid Sulphate Soil Material (ASSM).  The contemporary park now treats the urban stormwater discharge while providing dynamic spatial experiences that offer opportunities for human interaction with the natural environment.

Site Context

The Point Fraser Development is within Australia's Southwest Botanical Province ecoregion and is located in Perth's Central Business District along the Swan River.  The climate in Perth is Mediterranean, characterized by hot dry summers and cool wet winters with mean maximum temperatures in the low 30s Celsius (mid 80s Fahrenheit) and annual rainfall of 800 - 900 mm (31.5 - 35.5 in.).  The site is situated on reclaimed tidal river flat within the Swan Coastal Plain.

Syrinx Environmental PL: Point Fraser Development (Western Australia)

Sustainable Practices

• Stormwater Management: The Point Fraser site receives stormwater runoff from an 18 hectare (44.5 acre) catchment within the Perth Central Business District. Previously, untreated stormwater flowed directly into the Swan River, carrying high concentrations of nutrients, contributing to algal problems, as well as heavy metals, into the middle estuary. The site currently treats off-site and on-site stormwater via a series of innovative wetlands, vegetated swales, and pervious walling.
• Soil Protection and Remediation: The soils were tested and shown to contain acid sulfate soils, which produce sulfuric acid when exposed to oxygen, releasing toxic quantities of iron aluminum and other heavy metals.  During construction, best practice techniques for the treatment and removal of the acid sulfate soils included the construction of temporary limestone storage pads and dewatering ponds.  Soil was protected from disturbance to the greatest extent possible using low impact construction methods such as micro-tunneling and surcharging to sink potential acid material below the water table.
• Riparian and Habitat Restoration: Prior to redevelopment, the Point Fraser site was considered to have very low habitat value. Previous river reclamation projects leveled the site, replacing native habitat with lawn and scattered non-indigenous tree species.  The redevelopment of the park included riparian restoration and the re-establishment of resilient and diverse native habitats.  Areas receiving high wave impacts were treated by re-grading the riverbank to a more stable grade, applying bioengineering techniques, and planting indigenous riparian vegetation. Areas with lower wave impacts and existing riparian vegetation were stabilized with jute matting and infill planting. The Point Fraser Swan River intertidal zone now resembles a more natural environment, offering aquatic and terrestrial habitat and riverbank stability that provides a safer and more aesthetically pleasing landscape for the public.
• Public Access and Education: Because the site's location is ideal for tourism and recreation, public access and education are major project goals.  A series of interpretation trails covering topics related to the environment, history, and indigenous culture are designed to promote passive recreation and an intimate understanding of the site.  Signage and an information center enable the site to function as a dynamic educational and demonstration tool.
• Cultural: As one of the few permanent land features along the Swan River, Point Fraser is an important landmark for indigenous communities.  The area was known as Boodjargabbeelup, which means ‘the place of water and the land,' and was an important location for fishing and collecting shellfish. A variety of stakeholders, including Aboriginal representatives, were consulted during all phases of the project to ensure a culturally sensitive design that instilled a sense of community and promoted historical and cultural awareness.  One example is the exposed oyster shells.  This part of the Swan River is important in the local aboriginal dreamtime stories as a place where the great serpent, who created the rivers and the land, shook off its scales and rested.  These ‘scales' are visible today as the exposed oyster shells in the near shore sediments.  The site leads people to observe these shells and the interpretation shares the cultural significance of their presence.
• Long-term maintenance and stewardship:  A series of handbooks have been written for the City of Perth, to ensure all routine maintenance activities are undertaken as specified. The handbooks include procedures for maintaining the wetland, softworks, hardworks, and interpretation signage.  A site specific training program has also been established to ensure the City is completely independent in carrying out future monitoring and all maintenance requirements.

Construction Cost

The cost of installing the Point Fraser Wetland was an investment made by the City of Perth for the long-term protection of the Swan River. The creation of the wetland habitat and consequent improvement in the water quality entering the river assists in reducing and preventing environmental degradation, thereby reducing the need for costs associated with future environmental restoration and clean up projects.  This passive treatment technique has resulted in low construction costs, low energy output, and low long-term maintenance costs. The completed cost for the construction of the wetland was AUD $450,000 (USD $433,617), a small proportion of the AUD $9 million (USD $8.6 million) budgeted for the overall Point Fraser Development.

Instead of conventional hard walling practices, soft engineering techniques including brush mattressing and jute matting were used to prevent erosion along the intertidal zones until newly-planted vegetation could stabilize the area. The conventional practice of hard walling costs approximately AUD $2,500 per linear meter (USD $734.25 per linear foot), compared to the sustainable and more cost effective option of bioengineering employed at Point Fraser for AUD $400 per linear meter (USD $117.35 per linear foot).

Raised and tilted planes were designed into the landscape to address areas of the site with poor drainage, potential contamination, and acid sulfate soils, or where the water table was close to the surface. The mounded earthworks not only keep visitors away from the sensitive areas but by reusing the existing fill on site they reduce the cost of carting soil off site.  Every cubic meter of fill reused on site saved the client AUD $250 (USD $6.80 per cubic foot) in trucking and disposal costs.

Monitoring Information

• Wetland and Water Quality Monitoring: Stormwater treatment performance was assessed by monitoring water inflows and outflows to the wetland in conjunction with measuring water quality (e.g. amounts and types of nutrients and heavy metals entering and exiting the wetland). Collected data was then compared over time to determine the wetlands efficiency in removing nutrients and other pollutants. Results from monitoring undertaken since 2004 show progressive improvement in the wetland water quality; no events of elevated heavy metals have been recorded, total nitrogen levels are consistently below the trigger levels for the Swan River, and total phosphorus results leaving the wetland are below target levels, all suggesting that the wetland is functioning to performance targets.
• Sediment and Vegetation Monitoring: Sediment and vegetation were monitored in the first year of the wetland's operation to provide baseline information on nutrient and pollutant uptake, which has enabled detailed analyses of wetland performance in later years. Monitoring to date shows that vegetation is playing an increasingly important role in the uptake of nutrients and contaminants from the stormwater. Sediment contaminant levels, on the other hand, have decreased over time suggesting that the wetland is reaching maturity.
• Habitat Performance Monitoring: Measurements of habitat condition are based on the assessment of vegetation and the presence and density of various fauna groups. Habitat quality was measured by both the diversity and resilience of habitat types.

• FLORA: Prolific flowering and seeding of the plants, indicates good health and suggests that natural recruitment may be high in future years.
• FAUNA:

• Macro-invertebrates: A total of 14 different macro-invertebrate groups were identified during monitoring. Five of these are considered sensitive to disturbance and their presence indicates a healthy environment with good habitat development. A mosquito monitoring program was conducted in the wetland to obtain information on the mosquito population, assess the risk of disease-carrying species, and determine the need for a mosquito control program. The monitoring period revealed that the number of adult mosquitoes did not exceed the threshold indicator of an ongoing pest problem. Additionally, no known vector species were collected during the two-year monitoring program.
• Birds: During the monitoring program a total of 16 bird species were recorded in the wetland areas at Point Fraser; all were common species in Perth. Bird surveys were not conducted at the site prior to development but it is hoped that future monitoring will reveal an increase in the number and variety of bird species utilizing the site for feeding and loafing as the vegetation matures.

• Social Monitoring: The selected method for monitoring the social performance of the Point Fraser was through visitor observations. This monitoring was carried out over three days, two in winter and one in summer, and was split between weekdays and weekends. The questionnaire used when interviewing visitors was designed to more effectively understand the recreational, educational, and aesthetic value of the site. During the first year of social monitoring (18 hours of visitor observation) a total of 1,317 visitors were surveyed. Overall, responses to the active interview were very positive. Some general comments collected included:
  • Enjoyment of the interpretive signs not only for their information but also how they contribute to the aesthetics of the site;
  • Appreciation for the site's restoration and suggestions that more such sites should exist in the City;
  • Appreciation for the amount of planning and investment in the project;
  • Appreciation for the site's water quality benefits and general aesthetics.

Maintenance

• Construction activities at the site were closely controlled by a series of site specific management plans.  Monthly maintenance reports were submitted to the client and project team, outlining the project status and site condition, and informing the client of all maintenance undertaken or outstanding issues. A series of maintenance handbooks and trainings were developed for the City of Perth.
• To ensure the protection of the newly introduced native species and the establishment of healthy ecosystems, a weed control program was undertaken at all stages of construction and has continued as part of the maintenance program.  The first year of weed control cost AUD $12.00/m² (USD $1.07/foot²), however weed numbers have been significantly reduced and over the second year the cost dropped to AUD $7.00/m² (USD$0.63/ foot²), and in the third year to AUD $3/m² (USD $0.27/ foot²).
• Experience has shown that plant loss generally varies between 10% and 30% of re-vegetation works. Supplementary planting is typically implemented in response to these losses to prevent the establishment of weeds, limit erosion, and encourage the system to develop dense vegetation stands suitable for pollutant removal and habitat formation.  The cost for the supplementary planting was AUD $25,000 (USD $24,089), which included advanced trees and turf, dry land, wetland and foreshore areas.

Syrinx Environmental PL: Point Fraser Development (Western Australia)

Issues/Constraints of the Site

• The site contained acid sulfate soils and was geotechnically unstable and unpredictable.
• A significant challenge posed by the Point Fraser Development was ensuring that the project achieved its multiple objectives. The project not only aimed to treat stormwater to reduce elevated levels of nutrients and metals, but also focused on habitat creation, foreshore stabilization, weed management, and provision of public access and passive recreational, educational, and interpretive opportunities.
• Point Fraser's highly visible profile along the Swan River intertidal zone, along with its social importance, required the project design to be subtle while also encouraging maximum experiential engagement with the site.

Lessons Learned

• The Project was a great example of effective management of ASS (Acid Sulphate Soils), especially being located in the sensitive environs of the Swan River foreshore
• Extensive community consultation and social monitoring reinforced the firm belief that the local community is willing to take ownership of our environment and take an active role for its long-term protection.
• The knowledge base increased in terms of the integration of an accessible, functioning constructed wetland with a dynamic estuary environment.
• While the majority of the lessons learned, generally were with the benefit of hindsight, some aspects were actually foreseen to be potential occurrences.
• These include the following:

• When reintroducing natives into an area being restored, it proved important to pay attention to the quality of products associated with their establishment, such as soil or mulch that was imported to site. For example, weed species can inadvertently be imported via lower quality mulch. This exemplifies that being specific and rigorous with contractors and suppliers is beneficial for delivering the best possible end result.
• It is worth identifying significant, endemic trees early on in the process in order to ensure these existing trees are best retained for the future. This preserves existing habitats for fauna and provides shade for people.
• Adherence to the construction program proved to be critical for implementation. It is not worth compromising on timing of planting for the sake of a faster outcome, when consequently the overall result is less desirable to the long-term. For example, it is desirable to plant wetland species in spring to early summer (giving them time to establish for winter) and dampland or dryland species should be planted throughout the winter months.
• It is important to account for, and mitigate against, weather fluctuations and events when planning and assessing risk for restoration. As an example, river bank restoration at Point Fraser should have been undertaken in spring to take advantage of lower water levels associated with spring tides, reduced frequency and severity of storm events, and maximize peak growth periods for endemic shoreline vegetation. Implementation of works in winter was not ideal due to periods of higher water levels associated with winter tides and storm surge. Consistently high water levels in winter significantly reduced the daily/weekly timeframe available to undertake work, and therefore increased implementation risks.
• While an extensive amount of site specific information was available and considered, there is always an element of surprise that comes into the Project. For example, while site constraints are taken on board, it is important to allow room for spontaneity and growth in nature. Attention to detail is an ongoing lesson. For example, when incorporating rhizoid species adjacent hard surfaces, the design must take heed of their aggressive root structure and plant at least 300 mm (11.8 inches) from the edge of pathways.
• For Projects located on sensitive sites, if there is an opportunity to engage a 2-year maintenance period, this proves highly beneficial in order to ensure the best possible survival of native species and overall establishment of the restoration area.

More project details

http://www.perth.wa.gov.au/web/Council/Plans-and-Projects/Current-Projects/Point-Fraser-Redevelopment/

www.syrinx.net.au/projects/Point%20Fraser/pf-main.php
[Syrinx website in the process of being updated, 2008]

Project Consultants

Project Director:
Dr Kathy Meney
Company Director and Principal Scientist, Syrinx Environmental PL
Consultation, Contract Administration, Environmental Investigations, Client and Stakeholder Consultation

Design Director:
Debbie Kuh
Design Director, Syrinx Environmental PL
Design Management, Contract Administration

Operations Director:
Thomas Schwarten
Operations Director, Syrinx Environmental PL
Operations Management, Restoration, Contract Administration

Project Manager:
Khanh Nguyen
Construction Manager
Works Infrastructure Pty Ltd [currently Downer EDI Works]

Client:
City of Perth
Roger Blackburn
Project Manager
Urban Development Unit
City of Perth