Need design values for coir erosion control products

[obtuse]

My group needs to define allowable maximum shear stress and flow velocity values for streambank erosion control structures using "soft" materials, such as coir mats and coir logs. We employ these materials pre-vegetated with wetland plants integrated into the coir, but need initial values for the coir alone, before the plant roots begin to contribute to the strength of the installation.

I found a few sketchy studies with wildly varying results, mostly done by manufacturers or their consultants. I also understand that the USACE lab in Vicksburg may conduct an in-depth study of this question, but I need something sooner. Has anyone reading this had any actual experience using coir products on streambank or shoreline stabilization projects with enough time elapsed to offer at least anecdotal evidence of what kind of forces they will withstand?

As I see the issue, the allowable threshold boundary shear stress is limited by either the tearing strength of the outer netting of the coir product, or by the amount of force needed to move the entire unit of coir product. Therefore, to move a length of coir log, the current would have to lift the thing intact or to rip it apart. This is in either case a higher value than it would take to "erode" even a large particle from the surface of a natural bank .

Have any of you worked with this problem?

 

[VAD]

Hello Obtuse

Contact Robin Sottir. She has pioneered work with coir. She has co-authored book on Bio-engineering. Perhaps you have saw references.

Regards

 

[layfieldman]

You could try the ECTC, erosion control technology council.