A problem common to many wastewater treatment and storage lagoons is erosion of the interior slopes. Erosion may be caused by surface runoff and wind-induced wave action. The soils that compose the steep interior slopes of lagoons are especially susceptible to erosion and slumping from wave action. Embankment slope erosion caused by the failure of flexible, synthetic membrane liners is a particular concern. These liners, composed of polymer plastics or rubber compounds, or both, are primarily intended to act as seals to prevent leakage of wastewater from the lagoons. These liners have also been proposed as a low-cost method of erosion protection by their manufacturers, however, experience indicates the use of membrane liners alone has generally not been adequate for long-term erosion protection.