Bird is the Word: success at Eric Singleton Bird Sanctuary
Eric Singleton would definitely have agreed with Peter Griffin insofar as the bird being the word! Eric was a local bird enthusiast, conservationist, and long time resident of Bayswater, who successfully had the urban wetland lying at the end of Bayswater Brook approximately 8km from the city officially recognised for its environmental value. In his honour, and in recognition of his commitment to protecting natural areas home to many different birds, the wetland was renamed the Eric Singleton Bird Sanctuary.
In recent years, however, the wetland (which also used to be the site of a landfill) has struggled with degradation as a result of persistent weeds, rubbish and nutrient-drive algal blooms which meant that the local bird life slowly started to leave the nest. On top of that the City was having to pump large volumes of groundwater just to keep the wetland from drying out – one of the largest uses of groundwater in the local government area.
The adjacent Bayswater Brook main drain also discharges groundwater and stormwater into the Swan River and was found to be contributing some of the high levels of nutrients to the river system (the catchment was found to be the fifth highest contributor). As a result, the Swan River Trust (now absorbed into the Department of Parks and Wildlife) identified a need to reduce the annual nutrient load from the Bayswater Brook catchment by 30%. To achieve this the City formed a working group (and who doesn’t love a working group) with the Swan River Trust, Water Corporation, CSIRO and the Department of Water to develop a number of strategic documents to implement on ground Best Practice Management in Water Sensitive Urban Design. This included the:
1. Bayswater Drainage Implementation Strategy;
2. Bayswater Brook Action Plan; and
3. Bayswater Brook Water Quality Improvement Strategy.
Out of these strategies the Eric Singleton Bird Sanctuary Restoration Project was identified as the keystone undertaking for the improvement in water quality and ecological health of the wetland and Swan River, thus supporting the creation of a sustainable and diverse bird and wildlife habitat.
Essential Environmental’s Environmental Engineer, Halinka Lamparski, attended a technical tour and presentation of the Eric Singleton Bird Sanctuary Wetlands Project on Wednesday 27th April 2016, hosted by the Institute of Public Works Engineering Australasia (IPWEA) to learn a bit more about the technical details of the project and its progress. The tour was hosted by Jeremy Maher, Environmental Coordinator at the City of Bayswater, and Simon Cleary, Principal Engineering – Water Engineering at GHD.
The tour described how the City of Bayswater partnered with the Department of Parks and Wildlife to spent $3 million in design, construction and revegetation works to remediate the Sanctuary. The key elements of the project included:
- diversion of the continuous baseflow in the Bayswater Brook main drain into the wetland (up to ~50L/s = 100% of summer flows) in coordination with the Water Corporation, using a system of weirs which can be adjusted to allow more/less flow as required. Diversion of the baseflow has meant that groundwater is no longer required to top up the wetland;
- earthworks over the entire 2.6 ha wetland, including removal of rubbish from the old landfill site (tyres, car batteries etc.);
- installation of a 3 m x 3 m x 3 m gross pollutant trap between weir diversion and the wetland, cleaned of pollutants, sand, and rubbish once a month;
- a cap of crushed limestone was installed across the site to manage the Potential Acid Sulfate Soil conditions at the site and also allow the site to be trafficable;
- series of shallow and deep ponds to provide different habitats for different species of birds, including a sedimentation basin as the first entry point for baseflow into the wetland. The alternating ponds were also designed to provide a residence time of 12-24 hours for drain water to flow through the wetland for water quality treatment;
- ~400 mm layer of Bassendean sand was laid on top of the limestone to ensure that plants took up all their nutrients primarily from surrounding water
- the wetland was designed so that the more saline river water would not back flow into the wetland (and affect the freshwater vegetation)
- approximately 170,000 native seedlings were planted across the wetland in February 2015
Construction activity began in December 2014 and both earthworks and revegetation are now complete. On-going monitoring is being undertaken to measure changes in water quality between water entering the wetland and discharging into the Swan River. A university student is also undertaking an investigation into the actual residence time of diverted drain water and nutrient uptake throughout the wetland. The City expects that harvesting of wetland vegetation will be required as plants mature, possibly after 5 years, but this will be decided on an on-going basis from observation of vegetation and monitoring results.
The project has not only created a healthy wetland for flora and fauna, but its nutrient-stripping properties are also expected to prevent 1.3 tonnes of nitrogen, 200 kg of phosphorous, and 40 tonnes of sediment and other rubbish from entering the Swan River each year. This is approximately half of the target for nutrient reduction within the Bayswater Brook catchment. Harvesting diverted drain baseflows from Bayswater Brook has also secured a sustainable water source for the wetland and eliminated the need to pump groundwater into the wetland to maintain water levels.
The revitalised wetland has seen the return of many different birds including ducks, pelicans, white herons, swallows, robins, honeyeaters, and hawks, as well as a family of long-necked turtles (and very few mosquitos in sight! The bonus of high quality, flowing water). The laughter of kookaburras and the croaking frogs can also be heard by residents and visitors. No doubt, Mr Eric Singleton would likely be very satisfied with the outcomes of the project at the Sanctuary which his flocks of beloved feathered friends call home.