The Bletchley Park living stream is embedded within public open space adjacent to Lockway Street. This ephemeral living stream collects and conveys stormwater in larger rainfall events from the entire Bletchley Park Estate and is ultimately connected to the Southern River via the Water Corporation’s Forrestdale Main Drain. Embedded within the surrounding subdivisions and adjacent to the stream along Lockway Street, there are offline biofiltration areas and underground storage cells for treatment of small frequent events. These systems discharge into the stream in larger rainfall events. In major flood events there are areas of public open space where floodwaters can overflow from the stream and be accommodated within turfed areas of the surrounding public open space when necessary.
This section of the Bletchley Park living stream was constructed in 2015/16, replacing an existing agricultural drain (Balannup Lake Drain) which connected Balannup Lake and Lander Swamp (now renamed Castlewood Wetland) to the Forrestdale Main Drain. The design aimed to retain and reflect predevelopment waterway and wetland conditions and includes offline biofilters to protect the water quality of downstream waterways (Forrestdale Main Drain and Southern River beyond). The site’s naturally sandy soils are utilised to maximise infiltration on-site using underground storage cells and biofiltration areas.
This development has also implemented a trial of water quality treatment media embedded in trenches for subsoil drains which was undertaken in partnership with DWER and the City of Gosnells. The treatment media used in the trial (IMG – Iron Man Gypsum) is a by-product of Iluka Resources industrial processes.