RPS’ multi-disciplinary team has helped develop effective water management solutions for Riverhaven Estate; a 10.5 ha residential development beside the Canning River in Martin.
Historically used as an equestrian training and agistment facility and predominately cleared of native vegetation, RPS’ water management strategy was developed to work with the site’s natural features and surrounds.
Challenges for the team included the site’s existing network of drainage channels that conveyed untreated stormwater from the upstream road and semi-rural catchment to the Canning River.
Three channels were located within the site boundary and a larger, heavily eroded drainage channel was located to the south east of the site. The Canning River traces the southern boundary of Riverhaven Estate and an additional tributary is located along the north western boundary.
Information is power when it comes to water
RPS undertook pre-development groundwater and surface water monitoring for a two year period in order to establish baseline pre-development conditions. This was particularly important due to the shallow groundwater table and the site’s close proximity to the environmentally sensitive surface water of the Canning River.
RPS led a range of other water management activities for Riverhaven Estate including:
Groundwater monitoring which allowed us to develop a drainage system that incorporates subsoil drainage which provides a controlled groundwater level post-development and minimises the use of imported fill.
Obtaining a groundwater license that allows irrigation of the landscaping located within the Estate and re-vegetation works completed outside the development boundary.
Stormwater drainage design which removed the existing drainage lines within the site to prevent untreated stormwater from entering the Canning River, thereby improving the river’s water quality immediately. Degrading processes have been reduced significantly, with weed removal, erosion control and fencing works being completed to the Canning River and its nearby tributary. Close to 1 ha of the Canning River foreshore and tributary have been re-vegetated with local native plant species to improve the flora condition, diversity and habitat value, while controlling erosion and improving the aesthetics of the area.
A stormwater management strategy was developed for the Estate incorporating urban water best practice design. Roadside bio-filtration swales and native vegetation have been used, while soil amendments in drainage basins have been introduced to encourage at source filtration of stormwater and water quality treatment.
A Foreshore Management Plan was devised to determine the detailed landscaping and engineering works that will be completed in the foreshore zone. This project was undertaken over several years and was subject to rigorous assessment by the then Swan River Trust and City of Gosnells. The City and Trust were completely satisfied with every component of the foreshore works, which included the detailed stormwater drainage design, plant species selection and densities, maintenance commitments and the completion criteria.
Quality planning leads to quality improvements
In developing the Local Structure Plan (LSP) the former Swan River Trust agreed to consider a proposal to allow the development’s main stormwater infrastructure to be located outside the development boundary and in the foreshore of the Canning River if an improvement in water quality entering the Canning River from outside the development could be demonstrated.
The net result of the drainage infrastructure in the foreshore reserve has constituted a significant improvement to water quality but also the overall ecological health and recreational value of the area, in comparison to the degraded status and treatment of stormwater prior to the work being done. In addition, the public open space provided within the development is 100% useable and functional as the public open space does not provide a dual function use as would typically occur.
The Riverhaven Estate is a prime example of the benefits which can be achieved when residential development design considers and accommodates the total water cycle from the earliest project phases.
Riverhaven Estate is a finalist in the Australian Water Association Western Australian Water Awards for the WA Water Sensitive Urban Design (Grahame Heal) Award - Recognition of excellence in the delivery of total water cycle solutions.