Sediment logs are cylindrical barriers placed across slopes and drainage lines to slow water and trap soil before it reaches waterways.
Most erosion happens when water picks up speed. A bare slope after clearing or earthworks sends sediment straight into stormwater drains, creeks and dams.
Sediment logs break that momentum by sitting across the flow path, forcing water to slow down and drop its load of soil particles. This article covers the different types of sediment logs available in Australia, where and how to install them, and how they compare to silt fence.
Looking for sediment logs for your next project? All Stake Supply stocks coir logs in 150mm, 200mm and 300mm diameters, plus geotextile filter tubes and silt fence. Browse the full product range or contact the team for trade pricing.
Sediment logs (also called sediment control logs, filter socks or wattles) are tube-shaped barriers filled with organic or synthetic filter material. They sit directly on the ground surface across slopes, around drain inlets, or along the base of disturbed areas.
Water passes through the log slowly while suspended soil particles get caught in the fill material. Unlike solid barriers, sediment logs filter water rather than damming it, which reduces the risk of pooling and washout during heavy rainfall.
The term covers several products made from different materials. Coir logs use compressed coconut fibre wrapped in coir netting. Straw wattles use rice or wheat straw packed into a mesh sleeve. Synthetic filter tubes use geotextile fabric filled with gravel, sand or recycled material.
All Stake Supply carries coir logs and geotextile filter tubes from their St Marys warehouse, with delivery anywhere in Australia.
Sediment logs work through two mechanisms: they slow water velocity and they physically filter suspended particles. When stormwater hits the log, the fill material creates friction that reduces flow speed. Slower water cannot carry as much sediment, so particles settle out on the uphill side of the log.
The remaining water passes through the log body at a reduced rate, with finer particles caught in the fibre matrix. This is why sediment logs are classified as a velocity reduction measure rather than a complete barrier.
The filtration rate depends on the fill material and how tightly it is packed. Coir fibre has a natural filtration capacity because coconut husk fibres trap fine silt and clay particles as water moves through them. Geotextile tubes achieve similar results through the fabric weave.
On slopes steeper than 3:1 (H:V), sediment logs should be spaced closer together. A common rule is one log every 5-10 metres of slope length, depending on soil type and rainfall intensity. Check your local council's erosion and sediment control guidelines for specific spacing requirements.
These spacings assume bare soil conditions. Partially vegetated slopes need fewer logs.
Choosing the right sediment log depends on how long you need it, how much water it needs to handle, and whether you want it to break down naturally. Here is a direct comparison of the three main types used on Australian sites.
| Feature | Coir Logs | Straw Wattles | Geotextile Filter Tubes |
|---|---|---|---|
| Material | Coconut fibre + coir netting | Straw in mesh sleeve | Woven geotextile fabric |
| Lifespan | 2-5 years | 6-12 months | 5+ years (reusable) |
| Biodegradable | Yes, 100% | Yes | No |
| Filtration rate | Medium-high | Medium | High |
| Best for | Revegetation, waterway banks, permanent landscaping | Short-term construction, temporary stockpile protection | High-flow drains, inlet protection, long-term infrastructure |
| Typical diameter | 150-300mm | 200-250mm | 150-300mm |
| Anchoring | Hardwood stakes both sides | Stakes or pins | Stakes, pins or cable ties |
Coir logs are the most popular choice for projects that combine erosion control with revegetation. The coconut fibre breaks down over 2-5 years, which gives plants enough time to establish root systems that take over the stabilisation job permanently.
All Stake Supply stocks coir logs in four sizes: 150mm x 3m, 200mm x 2m, 200mm x 3m and 300mm x 3m.
Straw wattles work well for short construction phases where the site will be stabilised within 12 months. They are the lowest-cost option but degrade quickly in wet climates.
Sediment logs perform best when they intercept sheet flow before it concentrates into channels. The most common installation points are across the contour of bare slopes, around soil stockpiles, along the edges of construction access tracks, and upstream of stormwater drain inlets.
Sediment logs are not the right choice for concentrated flow channels with high velocity. If water is channelling rather than sheeting, you need rock check dams, gabion baskets or lined channels. The Australian Department of the Environment publishes guidelines on sediment control measures for sites near sensitive waterways.
If the drainage area above the log exceeds roughly 0.5 hectares per log, the volume will overwhelm the filtration capacity and the log will either float or get pushed out of position. For large construction sites, sediment logs work best as part of a layered system with silt fence at the boundary and sediment logs on internal slopes.
Poor installation is the main reason sediment logs fail. The log must sit flat on the ground surface with full contact along its length. Any gaps underneath create channels where water bypasses the filter entirely.
Never install sediment logs in a straight line down a slope. They must follow the contour (across the slope) to intercept water flowing downhill. A log placed down the slope does nothing except channel water along its length.
Stakes should be hardwood or steel, not softwood. Softwood stakes rot within weeks in wet soil and the log shifts out of position. All Stake Supply stocks steel fastening pins for securing erosion control products.
After installation, inspect logs after every significant rainfall event. Clear accumulated sediment when the deposit reaches one-third of the log height. A log buried in sediment is no longer filtering. The Australasian Chapter of IECA has published best practice guidelines on sediment control maintenance schedules.
Silt fence and sediment logs both trap sediment, but they work differently. Silt fence is a vertical geotextile fabric stretched between posts that ponds water on the uphill side, letting sediment settle before water seeps through the fabric. Sediment logs sit on the ground and filter water through their body.
This means sediment logs handle water more gradually and are less likely to fail from overtopping during heavy rain. On steeper slopes, sediment logs are generally more reliable because silt fence fabric tears under pressure from ponded water.
| Factor | Sediment Logs | Silt Fence |
|---|---|---|
| How it works | Filters water through fill material | Ponds water behind fabric barrier |
| Failure mode | Underflow from poor ground contact | Overtopping or fabric tear |
| Slope suitability | Works well on slopes up to 3:1 | Best on flat to moderate grades |
| Maintenance | Clear sediment at 1/3 log height | Re-tension fabric, clear ponded sediment |
| Installation effort | Moderate (trench + stakes) | Higher (deeper trench, posts, backfill) |
| Reusability | Coir logs biodegrade; synthetics reusable | Generally single-use |
Many sites use both. Silt fence at the perimeter catches the bulk of runoff leaving the site. Sediment logs on internal slopes reduce the load reaching the silt fence, extending its useful life.
Sediment log diameter determines how much water it can filter and how much sediment it can trap before needing maintenance. A 150mm log suits gentle slopes with light sheet flow. A 300mm log handles steeper grades and higher volumes. Getting the size wrong means either overspending on oversized logs for a flat site, or watching undersized logs get overwhelmed after the first decent rain.
For most construction and revegetation projects in Australia, 200mm x 3m coir logs are the standard. They balance filtration capacity, weight and handling ease. A 200mm coir log weighs roughly 12-15kg per metre, which two people can carry and position without equipment.
For larger projects or trade pricing, contact the team at All Stake Supply. With 48 years in the business and a full warehouse at St Marys, they ship complete orders anywhere in Australia so your site is not waiting on partial deliveries.
