Application of level spreader grass filter strips in south east Queensland, Australia for discharge reduction and passive irrigation

Application of level spreader grass filter strips in south east Queensland, Australia for discharge reduction and passive irrigation

A WSUD practice that has been implemented in the United States is the level spreader–vegetated filter strip (LS-VFS). A typical LS-VFS incorporates a concrete channel with a level control weir (level spreader) that evenly distributes flow to a downslope vegetated filter strip designed for stormwater infiltration. The application of LS-VFS in Australia has generally received little attention. Given the absence of local information, this paper provides a 'proof of concept' analysis of LS-VFS as applied to South East Queensland conditions. The main focus of the analysis is to determine how compatible LS-VFS are in terms of meeting the prescribed WSUD frequent flow targets for urban stormwater discharges.
Key LS-VFS design requirements were identified from the literature. A MUSIC model analysis was performed to evaluate the expected runoff reduction associated with a LS-VFS receiving stormwater from a Brisbane residential subdivision. Indicative criteria are proposed for design discharges, soil suitability and sizing of the filter strip dimensions. The potential of LS-VFS to provide 'passive' irrigation was recognized and the application of LS-VFS for sustaining green cover within urban open space was also analysed. Recommendations are made on further research and investigations on the Queensland application of LS-VFS technology.

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