Jan. 10, 2022
What is an erosion control blanket?
Erosion control blankets are blankets of synthetic or natural fibers used to protect soil from the erosive effects of rain and water flow, usually in slopes and channels. Erosion can be the result of rainfall, wind and severe weather.
These products act as mulch by helping to retain moisture and allowing for more reliable establishment of vegetation. By covering open areas of land with these mats, you can help prevent soil movement and promote the growth of new plants. Erosion control blankets are sometimes referred to as rolled erosion control products, erosion control fabrics, mats, nets and blankets. These refer to materials that are applied to the soil to keep it in place.
Native vegetation should be installed with erosion control fabrics because blankets address only surface erosion and most are designed to decompose over time. Native vegetation has an extensive and diverse root system that provides long-term protection against surface and subsurface erosion. They can be used to prevent slope erosion, avoid river scour and stabilize shorelines until native vegetation forms.
There are many different types of erosion control blankets, some synthetic, some natural, and mixtures of both. These blankets can be made of straw, coconut fiber, aspen fiber, jute, and polypropylene (plastic). Most of these blankets can be purchased in a variety of sizes. A common one is 80 to 100 square yards. Most of them are rolled up and cut into widths of 3 to 8 feet.
Erosion control blankets are a good solution for use on steep slopes, over ditches, next to driveways and at construction sites. As part of a system, they can be used with or without retaining walls.
Types of Erosion Control Blankets
Open weave vs. continuous fiber products
Erosion fabrics come in two forms: woven webs with open spaces, and continuous fiber blankets attached to the mesh.
Mesh materials can be natural or synthetic, and some synthetic meshes may be photodegradable.
The fibers may be sewn to a mesh layer or sandwiched between two mesh layers. Continuous fiber blankets completely cover the soil surface and are often used on steep sites or drainage channels.
How long will an erosion control blanket last?
The type of blanket you choose depends on how long you want it to last in the environment. Some accelerated products have a very short functional life. These blankets are made from agricultural straw and sewn together with a biodegradable net. If the blanket will last up to a year, a thicker option made from the same material or wood chips and natural fibers is available. Extra-long blankets are designed to protect an area for up to 2 years. These are made stronger and combine materials such as straw, coconut fiber, polypropylene mesh and UV stabilizing threads. Permanent blanket options are also known as turf reinforcement mats. They are strong enough to withstand the harsh conditions found on slopes, shorelines, riverbanks and high traffic channels.
When should I use erosion control blankets?
Factors in selecting an erosion control blanket include soil conditions, steepness and length of slope, shear stress, and the type and duration of protection needed to establish the desired vegetation. Products are available for a variety of uses and service lives, typically ranging from 3 months to 36 months to permanent applications. Follow the manufacturer's specifications to select the proper type of blanket.
How to Install Anti-Corrosion Blankets
Follow the manufacturer's installation specifications, paying particular attention to inspection slots, fastening device (staple) requirements, and the need for firm contact with the soil.
Installing an erosion control blanket is relatively easy. Ensuring that water flows over the top of the blanket is of utmost importance. You must "key" it into the slope by digging a depression (a small trench along the contour of the top of the slope). Place the top of the material into the trench to line it up. Fold the top edge to form a secure joint and secure it with staples. Then fill the trench to the previous soil level. The upwind edge of the blanket needs to overlap underneath the blanket next to it. This will ensure that the soil erosion blanket stays in place.
Proper installation is the key to success. To work, erosion fabrics must be in constant contact with the soil; fabrics that cover soil voids will not prevent potential erosion. It is best to install them in areas that are as smooth as possible. They are particularly difficult to install properly in areas with fleece or uneven or rocky terrain. Mats are usually installed with galvanized landscaping staples (6" staples are sufficient for most applications). Biodegradable corn or wood stakes can also be used.
Potential problems with using erosion control blankets
Mesh in continuous fiber fabrics has raised concerns among wildlife conservationists because of their potential to entangle wildlife. Injuries and deaths to snakes from mesh have been documented. To reduce the impact on wildlife, new mesh designs have been developed that allow the threads to move so that the openings can be enlarged. Even continuous fiber fabrics may not suppress invasive weeds, and mesh may impede weeding efforts. Erosion control fabrics do not protect against erosion from subsurface forces and may provide false sense of security. Natural fiber mesh is more biodegradable than synthetic fiber mesh, but it costs more.
Maintain areas covered with erosion control blankets
Inspect weekly and within 48 hours of each rainfall event that results in stormwater runoff from the site until adequate vegetation is established. Repair erosion and/or damage at the top of slopes. Repair damage under the blanket. Pull back the blanket, fill and compact the eroded area, reseed, and then securely fasten the blanket. Reposition or replace blankets that have moved along the slope or have been damaged.
For the first year after installation, mats should be checked every 2-3 months to ensure good contact between the mat and the soil. Also check the bottom of the mat for signs of inhibiting plant material. The mat may also inhibit species spread by runners. Once individuals are established, the mat can be cut out to allow more space for dispersal.
Should I remove erosion control blankets?
If project goals are taken into account when selecting a natural fiber product, the mat should decompose in place within an appropriate timeframe and does not need to be removed. Erosion control blankets are typically left in place and designed to degrade over time.