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A variety of products are available to protect shoreline embankments from erosion. Both biodegradable and non-degradable Erosion Control Blankets (ECBs) are designed to cover mild vegetated slopes to protect against surface erosion and seed loss before vegetation is established. As the slope gradient increases, non-degradable synthetic Turf Reinforcement Mats (TRMs) offer the next level of protection — but their performance is limited when the slope angle increases and the slope is exposed to water contact and saturated conditions.

Topsoil is placed in a 3D confinement network.

3D deep slope-surface protection

GEOWEB 3D soil confinement can meet those challenges through the system’s deep 3D cellular structure. The cellular network encapsulates infill within each cell and functions as anchored containers in the upper soil layer — minimizing movement and potential for migration of the embankment materials. Stabilization of the shoreline slope-surface materials prevents severe erosion and controls rill and gully formation — especially in areas of concentrated sheet flow and over erosive soils.

GEOWEB protection systems are also flexible solutions that can be designed with a variety of infill types depending on slope vertical height, slope length, slope angle, depth of flow, anticipated high water level, and flow velocities — as well as wave action or ice push. Typically, the GEOWEB slope protection system is anchored with either steel, or fiberglass ATRA anchors. But, a tendoned anchoring system may be included for additional stability, or when stake anchors cannot be used such as when the system is placed over an impervious liner.

For shoreline embankments exposed to swift water movement, varying water levels, or wave action, more vigorous hard-armoring may be required. Concrete systems offer the most robust hard-armor protection. Concrete-filled GEOWEB sections are flexible articulating mats that are more economical than articulated concrete block systems (ACBs), according to Presto Geosystems. The concrete is poured in place within the cellular network without additional reinforcement.

A Turf Reinforcement Mat covers a 3D soil confinement system.

Site-specific design solutions

Shorelines designed with 3D soil confinement systems allow the use of varied infill on a single project to address site-specific requirements. Examples include the following:

  • Concrete may be designed only to a point just above the high water line, allowing vegetation and natural aesthetics on the upper embankments above the high water line.
  • A TRM cover designed over a vegetated GEOWEB system reduces potential for topsoil loss caused by water impact.
  • Large rip-rap may be designed at the toe of vegetated or concrete systems to protect from water impact as well as reduce the potential for undermining.

Because 3D soil confinement systems are able to support a variety of infill types, design consideration is placed on the characteristics of the shoreline embankment (soil conditions, slope height, length and angle) as well as its contact with the water to ensure long-term performance and sustainability.

Information provided by Presto Geosystems (www.prestogeo.com).