Erosion Barrier Applications

What – Lightweight synthetic or organic mats (netting or blankets) staked to soil surface.

Purpose – Intended to provide temporary (several months to years) soil stability to special interest sites (e.g., heritage resources) until vegetation can establish.  Mats also reduce soil temperature and provide moisture conservation.

Effectiveness – products are expensive, but effective when installed correctly.

Where

• Small areas with high values at risk.

Cost – $0.35–1.00 per square yard + installation (labor).  Additional factors include:

• Site location and access

How to Links – See USDA BAER Catalog page 37 (PDF page 45); and NRCS Erosion Control Mats Fact Sheet.

What – Logs are partially entrenched or/and staked to soil surface parallel to the contour.

Purpose – Intended to slow runoff, cause localized ponding, and capture and store eroded sediment when arranged in a bricklayer pattern on hillslopes. 

Effectiveness – Studies indicated that log erosion barriers may reduce runoff, peak flows, and sediment yields for low intensity rain events (< 1.8” per hour), but are unlikely to have a significant effect for high intensity rain events.  Sediment storage was reported to decrease by 10–15% with each successive rain event.  Although the potential volume of sediment stored is dependent on slope, tree size and length, frequency, and use of berm traps, with proper implementation effective sediment storage and creation of microsites can be achieved.

Please note: some agencies, such as the US Forest Service, no longer endorse this method. However, other users have reported success with this method when logs are properly placed and secured. Please consider the cost, ease of application, and safety, and consult with experts in the post-fire treatment profession who can provide perspective, insight, guidance, and advice in an ever evolving field of practice. 

Where

• Hillslopes with high- and moderate-burn severity.
• Slopes between 25 and 60 percent.
• Soils with high erosion-hazard ratings.
• Watersheds with high values at risk.

Cost – $420–1200 per acre.  Additional factors include:

• Terrain
• Site access
• Frequency of logs
• Labor experience

How to Links – See USDA BAER Catalog page 45 (PDF page 53); and NRCS Log Erosion Barriers Fact Sheet.

What – Fiber rolls, commonly called wattles, are prefabricated rolls manufactured from rice straw and wrapped in degradable netting.  In some cases, on-site woody debris can be rolled in netting to reduce costs.  Rolls are ~ 9 inches in diameter and up to 25 feet long. 

Purpose – Intended for low-surface flows not to exceed 1 cubic foot per second. They are not for stream channels or gullies.  They are intended to reduce erosion by shortening the slope length to slow overland flow velocity as well as trap sediment and provide a seedbed for vegetative recovery.

Effectiveness – Studies indicated that erosion barriers may reduce runoff and sediment yields for low intensity rain events (< 1.8” per hour), but are unlikely to have a significant effect for high intensity rain events.  Wattles reduced total runoff and peak flow rates (Robichaud et al. 2008 and 2010).

Where

• Areas of high- and moderate-burn severity.
• Slopes with < 40% ground cover.

Cost – $1100–4000 per acre.  Additional factors include:

• Location and terrain
• Access
• Experience of crews

How to Links – See USDA BAER Catalog page 51 (PDF page 59); and NRCS Contour Wattles Fact Sheet.

What – a permeable fabric installed parallel to the contour and anchored with wooden stakes or metal t-posts.

Purpose – Intended to trap sediment and protect areas with high values at risk including heritage resources, water quality, and aquatic resources.

Effectiveness – Studies reported notably high effectiveness when fences were installed properly (i.e., anchored into soil and water allowed to pass through slowly while trapping sediment) and maintained (which requires significant effort and attention).  Robichaud and Brown (2002) measured trap efficiency at over 90 %. 

Where

• Areas accessible for inspection and maintenance.

Cost – $50 per roll (material); $150–250 labor for each fence installation.  Additional factors include:

• Location and terrain
• Frequency of fences
• Soil characteristics

How to Links – See USDA BAER Catalog page 56 (PDF page 64); and NRSC Silt Fence Fact Sheet.