TRM 2

[johnhan76]

Has anyone had any experience with turf reinforcement mats? i am interested in using them instead of the conventional rip-rap but dont quite have the confidence in them yet.

 

[cskelsey]

The Erosion Control Technology Council is a great resource.

http://www.ectc.org.

There should be some free information and contacts there to assist you, including testing and specification assistance.

In general, TRMs provide long-term/permanent reinforcement and erosion control. Often they are composites, with biodegradable materials (used to establish vegetation) mixed with synthetics (used to provide stability against erosive forces). The degradable-nondegradable construction is largely determined by site-specific needs. Most TRM manufacturers offer a wide-range of products and have design personnel to help you in your selection.

Again, start with ECTC. It's an excellent organization.
-cK

Christopher Kelsey, editor
GFR magazine
gfr@ifai.com

http://www.gmanow.com

 

[layfieldman]

I'm not sure how things are graded down in the US but here in Canada we consider anything that has a biodegradable component as an RECB (rolled erosion control blanket) regardless of the netting. TRMs (turf reinforcement matting) tend to be fully UV stabilized geosynthetic materials which are meant to be permanent, allowing roots to grow through it.

They both do the same thing as the biodegradable portion (straw or coconut fibre) of RECB's do not promote growth in themselves, they just offer protection from wind and water so that growth can occur without erosion. This does have the effect of faster growth. Then they biodegrade (photodegrade for the netting) so that nothing is left behind.

TRMs also do the same thing but offer permanent root reinforcement in higher water flow situations or steeper slopes. They can also be used without vegetation in place of riprap to slow water velocities (such as storm water drainage channels).

cskelsey is right that you can check with manufacturers for properties and applications as well as the ECTC. Many companies offer design CD's which ask for many parameters then output various material choices.

 

[Krautso]

I hope this helps.

Turf reinforcement mats tend to be celled (honeycombed) synthetic materials which are placed prior to topsoil placement and seeding. The topsoil then fills these cells when placed. These mats are considered to be permanent topsoil slope reinforcement as they last well over 5 years provided they are covered completely and protected from direct sunlight and weathering. They are usefull where you have steep slopes but ample growing season and a good seedmix to ensure a successful catch.

Erosion control blankets (synthetic or otherwise) are installed over topsoil which has already been seeded and offer protection to the area for a couple of seasons max to allow for a successful catch. The drawback to these blankets is that you aren't able to return the following season to reseed if you don't have a successful catch. I have personally used synthetic erosion control blanket in place of rip-rap in ditches which have a highly erodible soil type (silty sand)and severe grades(+3%)and intermittent flow. It worked great.

I would not suggest using this material in place of rip-rap at culvert inlets/outlets or any ditch which is expected to carry water constantly. You won't be able to get anything to grow and all blankets will degrade if exposed.

Cheers

 

[ken103162]

We have used ECB's and TRM's extensively. Briefly, (1) you need to identify the shear force which will be exerted by the water; (2) examine the options available for erosion protection (vegetation - ECB - TRM - Armour such as rip-rap, gabion, concrete, ect) and choose your protection based on the required resistance to the shear. Also consider whether you only need temporary protection (6 mo to 1 year)while vegetation is established or you need both temporary and long-term protection. Don't forget to determine the shear force based on no vegetation (after construction) and with vegetation.

We've used both ECB's and TRM's on long, steep slopes. They've worked well and the TRM's have provided excellent long term protection. ECB's and TRM's for channel protection can also be an excellent choice. But in either case it is necessary to pay attention to the details of construction both in preparing your specifications and ensuring that the construction is performed properly.

A good vendor supplied design program is provided by North American Green. NAG also has good installation details, specifications and other design guidance information.