One of the strategies of Revitalising Geographe Waterways is ‘Innovation and Remediation’, aiming to fast track water quality improvements in key Geographe waterways through innovative technology and remediation and by implementing key actions from water management plans. The Vasse Taskforce has prioritised investment in these projects because they address an immediate need and can deliver water quality outcomes in the short-term.
The Vasse Wonnerup Wetlands Partnership is proposing to undertake removal of approximately 330m3 (around 62 tonnes) of sediment in the Vasse Estuary alongside Estuary View Drive in Wonnerup. The project will remove sediment along a 220m stretch that is exposed over summer months when water levels are low. Build-up and exposure of black ooze sediment in this area is thought to contribute to offensive odours over summer months, impacting livability for neighbours.
The project is expected to commence in winter 2022, when water levels are high and waterbird numbers low. Sediment will be removed and pumped into three geotextile bags using an unmanned dredge or micro dredge. Sediment will be retained in geotextile bags on a bunded and fenced area on the shoreline allowing water to drain out. Water will be treated before exiting through a pipe back into the estuary. For more details, view the project factsheet.
A layer of nutrient-rich, fine organic sediments has accumulated throughout the Lower Vasse River with an average depth of 450mm. This sediment provides an internal source of nutrients that contributes to algal growth in summer months.
The City of Busselton is leading this project to remove sediments from the lower sections of the river. Stage 1 was completed in June 2022 and removed an estimated 630 tonnes (dry solids) of sediment between the Butter Factory Museum to the Causeway Road Bridge in Busselton. The technique used a micro-dredge and dewatered sediments using geotextile bags; the first large scale application of this technique locally within these environments. Silt curtains were erected on either side of the dredging area to prevent impacts to water quality in the rest of the river and the Vasse Wonnerup wetlands.
Stages 2 and 3 have now been funded through the City of Busselton and the State NRM program. Stage 2 will occur between the old Boat Ramp and Causeway Roade Bridge in April 2023. Stage 3 is planned for the section upstream of the Strelly Street bridge in 2023-24.