Rip-rap is commonly used as erosion protection for culverts, stream banks, beachfronts, drainage channels, slopes and other areas subject to erosion by water. However, rip-rap alone is often not enough to prevent erosion. Scouring and migration of soil particles through the rip-rap can undermine its effectiveness. A well-chosen erosion control geotextile will greatly improve the performance and lifespan of rip-rap.
- Prevent Undermining of Rip-Rap
- Choose the Correct Erosion Control Geotextile
- Identify Soil Type
- Calculate Strength and Flow Characteristics
- Nonwovens For Clays
- Monofilaments for Fine Grained Sands
The engineer has several options when selecting the type of erosion control geotextile to place under rip-rap. Multiple factors must be taken into consideration. The soil type and its percentage of fines plays a very important role in choosing the correct geotextile. The weight and angularity of the rip-rap and the height at which it is dropped will determine the required geotextile strength. Finally, anticipated water flow must be calculated.
Nonwovens are cost-effective and perform very well with clays, coarse sands and aggregates. For fine-grained sands a woven monofilament is the correct option. Fine grained sands will cause nonwovens and slit-film wovens to clog. Woven monofilaments allow the finest sand particles to pass directly through them without getting clogged. Consult our riprap installation guide for more information on this subject.