Landslide Repair and Severe Erosion Mitigation Case Studies in Sensitive Coastal Areas

Landslides and severe erosion along our nation's coastlines can present a real challenge to engineers, planners and designers. Not only are the regulatory hurdles associated with construction in sensitive coastal zones significant, many of the common tools available either present a large environmental impact or are not robust enough to handle the corrosion, scour, rapid drawdown, wave action, and other erosion processes associated with coastal sites. In the context of case studies from three coastal projects across the United States, this paper outlines some of the new and innovative erosion control and landslide mitigation methods available to designers that are both robust enough to survive coastal conditions and specific enough to prevent unnecessary environmental impact. Relevant technologies include traditional soil nailing, high capacity tensioned wire mesh with vegetative inclusions and/or seeded turf reinforcement mats, reinforced architecturally sculpted shotcrete, scour micropiles, and fiberglass composite launched (or ballistic) soil nails/horizontal drains. The case studies within this paper include a Pacific coastal bluff erosion project using fiberglass ballistic soil nails and architecturally sculpted/stained shotcrete near Crescent City, California; a lakeshore erosion repair using high-strength galvanized steel mesh, launched steel soil nails and native plant impregnated cellular confinement coir on the West Shore of Lake Tahoe in California; and a Pacific coast bluff slide repair using a subsurface combination of horizontal self drilling soil nails and reticulated micro piles along California's scenic Hwy 1.