Penrith City Council in NSW is measuring the success of a pilot project utilising an innovative treatment technique for stormwater flow discharging from a mixed residential/semi rural catchment area.

Assisted by the State Government’s Stormwater Trust, the Scope Creek Olympic stormwater project, which began in 1999, required seedlings to become a fully grown woodlot to act as a nutrient sink.

The woodlot ensures a nutrient uptake on sloping, elevated land along the southern portion of the site and stands above the limit of frequent channel flows to ensure functional separation.

Key to the system is a subterranean SPEL Stormceptor system supplied by All Pumps Sales & Service. which engineered the solution showing cost effectiveness, modular design and ease of installation. SPEL Stormceptors employ a bypass system. Untreated water containing dirt and oil enters the system and silt sinks to the bottom while the oil floats to the surface. As the flow increases during heavy rain, the system bypasses an increasing percentage ducted from the cleanest zone in a primary chamber through to a bypass chamber before final discharge.

Significant features include good access to all parts for de-sludging, a dip pipe inlet for minimum turbulence and to prevent inflammable vapours passing upstream, and tank exterior treatment called ‘flow coat’ that acts as a water penetration barrier.

Scope Creek comprises a catchment of about 2200 hectares which connects to the Penrith Lakes Scheme. Water quality within the venue elements of the Penrith Lakes Scheme was required to be maintained at near primary contact levels. As such, it was stipulated that contributing catchment inflows should be pre-treated as effectively as possible.

The project addresses litter, sediment, vegetative matter and other similar materials mobilised by stormwater low flows by removal and treatment techniques including gross pollutant/sediment traps, light liquid separators and biological methods.

Treated flows are temporarily stored and then applied to this fully grown woodlot (nutrient sink) on the adjacent land using irrigation techniques.

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