Clem Sturmfels, Land Management Extension Officer
Fire damaged netting and steel posts can be repurposed to become a valuable resource to construct sediment traps after a bushfire.
Sediment traps are commonly installed following bushfires to protect dams, roads, tracks, stream crossings and a range of environmental assets from fire debris and sediment that can be washed downstream after heavy rain.
Issues like soil erosion, landslides and the movement of ash, soil, organic matter and woody debris are a common occurrence following rain events in bushfire affected hilly terrain.
Sediment traps can be easily constructed from fire damaged netting and steel posts by simply building a fence across your main drainage lines to slow water flow and capture sediment.
The length of the fence will depend on the size of the catchment and availability of suitable materials.
Unlike a normal fence, which is usually straight, a netting fence sediment trap needs to follow the contour of the land. This allows the water to move in both directions away from the drainage line. The path of the netting fence sediment trap should follow a level line, along a contour, somewhat similar to a sheep or cattle track around a hill.
To prevent water from running around the ends, turn both ends of the fence slightly uphill. The netting needs to have good contact with ground and should be supported with steel posts spaced 1 to 2 metres apart to keep it secure in heavy flows.
The netting fence sediment trap works by slowing and filtering the water resulting in material being trapped against the fence but also depositing sediment upstream.
Regular removal of debris and sediment will prolong the life of the structure.
