Construction Works are progressing on the Entry Wetlands and Skeleton Creek.
The Marigold construction team have now completed the civil works for the Northern Wetland (you can read our previous update here) and landscaping works are set to commence shortly.
In addition, the team have now turned their attention to delivering the Civil works for the Southern Wetland and Future Waterway (creek area).
Read on for a re-cap and breakdown of what the civil works entail!
The wetlands are set to become a visual and attractive feature of the community but also serve a practical function by capturing and cleaning the storm water run-off from the community. It is a pretty impressive feat of engineering that utilises a natural way to treat and remove pollutants from stormwater before it enters our creeks, rivers and oceans.
Constructed wetlands typically have three design features that work together to help filter stormwater and protect the area from flooding:
• inlet zone – a sediment basin that removes coarse sediment
• macrophyte zone – a shallow area densely planted with aquatic plants and the main part of the wetland, which removes fine particles and dissolved pollutants
• high flow bypass channel – lets excess water flow around the wetland without damaging the plants
These three areas of the wetland use three different methods (physical, biological and chemical uptake, and pollutant transformation) to clean the water.
The wetlands large open water section (inlet zone) is designed to be big enough to capture a sufficient amount of water. This design also helps to disperse the flow of the water across the width of the wetland to slow it down. This ensures there is sufficient time for the water to be cleaned and filtered to maximum potential. The water is slowed to a point where the sediment drops out of the water column by gravity, which can then be collected in the sediment pond.
Pipes and drainage are added to also assist with controlling the flow of water, to move water from the sediment pond to the macrophyte section and to eventually transport the water into the wider water network. Once the pipes and drainage system were completed, the construction team began layering the bed of the wetland with the different ground coverings which are one of the physical methods wetlands used to help clean and filter the water. The layers are made up of crushed rock and different sediments. One such layer is gypsum.
Water will move from an area of low salt concentration to an area of higher salt concentration. Soils with lots of salt (such as those with high clay content) may look moist but plants cannot absorb this moisture. Gypsum helps this by binding to the clay particles (chemical removal) in the water which allows the plants to use the moisture stored in the soil.
First layer of gypsum stabilized clay liner installed. Gypsum is then mixed & compacted into the clay.
The balance of the civil construction work is anticipated to be completed in the coming weeks. This is perfectly timed to commence the landscape scope in the following month at the height of Spring.
Spring is the opportune time to complete landscaping as we are blessed with ample sun and rain which is exactly what freshly sown plants and grass require to grow.
The selected wetland plants (hydrophytes) that will be included in the wetland and surround the immediate area of the reserve, also play a role in the removing of sediment and filtering the water to improve the ecosystem.
Stay tuned for more construction updates!
