Course Length:  1 hour

Sponsored by ASCE Continuing Education and the Geo-Institute (GI).  

Purpose and Background

Capillary barriers form in unsaturated soils when there is a pronounced textural contrast between adjacent layers. Capillary barriers have become an important technique for controlling unsaturated water movement, such as limiting infiltration into buried waste or preventing water rise into heave-susceptible soils. In some cases, capillary barriers are used to laterally drain unsaturated water. A range of materials can be used to create capillary barriers, including natural, recycled and geosynthetic materials. This webinar discusses the principles of how capillary barriers function, how to estimate capillary barrier performance, and design applications for capillary barriers.

Primary Discussion Topics

• Unsaturated water movement
• Material properties relevant to the capillary barrier effect
• Design of capillary barrier systems

Learning Outcomes

• Explain how a capillary barrier is formed in unsaturated soils
• Interpret properties relevant to capillary barrier performance from test data
• Identify materials used in a capillary barrier system
• Develop estimates of capillary barrier performance

Webinar Benefits

• Learn new approaches for controlling water movement in unsaturated soils
• Discover how to evaluate and select materials for use in capillary barrier systems
• Determine expected performance for capillary barrier systems
• Identify limitations of capillary barriers
• Recognize applications of capillary barriers
• Investigate the potential for unsaturated lateral drainage using capillary barriers
• Identify inadvertent capillary barriers that may affect water movement and drainage

Intended Audience

• Geotechnical engineers
• Hydrologists and drainage engineers
• Pavement design engineers
• Waste site operators and regulators

Webinar Outline

• Introduction to capillary barriers
• General description
• Applications
• Unsaturated water movement
• Flux law
• Unsaturated properties 
• Water movement in layered soils
• The capillary barrier effect
• Properties relevant to capillary barrier performance
• Breakthrough and restoration head
• Soil and geosynthetic material properties 
• Applications in cover systems 
• Estimating water storage capacity   
• Design elements and performance
• Applications to limit upward water movement
• Unsaturated lateral water movement using capillary barriers
• Lateral diversion length
• Drainage configurations