Internal Erosion – Applying Erosion Mechanics From ICOLD Bulletin 164 In Internal Erosion Failure Mode Analyses

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Internal erosion causes about half of all failures of water-retaining earth embankment dams. Similar statistics apply to levees. Internal erosion occurs when the hydraulic loads imposed by water seeping through the pores or flowing through cracks and openings in the soils in embankments and their foundations generate erosive forces sufficient to overcome the resistance to erosion of those soils. The knowledge of internal erosion processes has advanced significantly over the past two decades. The two volumes of ICOLD Bulletin 164 (ICOLD 2017, ICOLD, 2016) reflects the results of a group of international experts to collect information from experience, case histories and research to provide guidance on internal erosion for engineers in dams and levees. The accumulation of knowledge led to the definition and understanding of the mechanics of the four modes of internal erosion. This understanding of internal erosion mechanics makes it possible for engineers to estimate the hydraulic load that will likely cause internal erosion to failure. The mechanics of the modes of internal erosion (mechanisms) can be combined with the internal erosion pathways through embankments and their foundations to developed detailed descriptions of potential failure modes (PFMs). If desired these detailed PFM descriptions can be used in quantitative risk analyses. This webinar will include discussion of all of the concepts described above, with reference to how the Bulletin provides a reference to the application of these concepts in dam safety evaluations and risk analyses.

Five Learning Objectives of This Course:

  • Exposure to the international knowledge concerning internal erosion reflected in ICOLD Bulletin 164
  • Understanding of the four mechanisms of internal erosion (IE)
  • Understanding of how IE mechanisms combine with pathways to create potential failure modes
  • Improved ability to estimate IE erosion risks, both quantitatively and qualitatively
  • Improved ability to identify vulnerabilities to internal erosion for existing dams and levees

Rodney Bridle

Principal, Dam Safety Ltd.

Rodney Bridle is the UK Member of the ICOLD Technical Committee on Embankment Dams. He is the editor and part-author of the two volumes of ICOLD Bulletin 164 on Internal Erosion in Existing Dams, Dikes and Levees, which deal primarily with the mechanics of internal erosion. To spread this important new knowledge he has written papers, participated in workshops and made many presentations around the world. Rod is a widely experienced consulting civil engineer specializing in the performance and safety of embankment dams. His particular present interest is in applying new and old knowledge to understand the behavior of the now large numbers of existing embankment dams and levees to make them safe and economically effective. He has completed many quantitative risk assessments using UK guidance; some were presented at ASCE Geo-risk in Denver in 2017 and at ICOLD in Vienna in 2018. He has supervised substantial and minor safety works at dams vulnerable to internal erosion. He is  a member of BC Hydro’s Expert Engineering Panel with Emeritus Professor Robin Fell (University of New South Wales, Australia) and Dr Kaare Hoeg (Norwegian Geotechnical Institute) reviewing the seepage control functions of existing high dams in Canada. He was a Partner and Director of Watson Hawksley and Montgomery Watson (later MWH, now Stantec) and is a former Chair of the British Dam Society and a life member of USSD.

John W. France, P.E., D.GE, D.WRE

President, JWF Consulting, LLC

Mr. John France is a registered professional engineer employed by AECOM as a Vice President and National Technology Leader for Dams. He received BS and MS degrees in civil engineering from Cornell University. Mr. France has 42 years of consulting engineering experience, during which time he has worked on hundreds of civil engineering projects. For the past 35 years his professional career has been focused on dam engineering and dam safety services. During his career, Mr. France has been involved in various capacities in evaluating and remediating seepage issues for earth dams. He has written numerous papers on the topic, and in 2012 he was an invited speaker at a FEMA workshop on filters and seepage remediation. He was also engaged by the Montana Dam Safety office to prepare a technical note on chimney filter design for posting on the State’s website. Together with Jennifer Williams he has presented workshops on internal erosion failure modes for ASDSO and the States of Colorado and Wyoming.

    • Introduction to ICOLD
    • Need for guidance – failures, fatalities, speed of failure
    • Bulletin responds to needs – new knowledge
    • Mechanics of internal erosion – failures when water level high during floods
    • Four internal erosion failure modes, estimating water levels causing internal erosion failure, case histories
    • Contact erosion
    • Concentrated leak erosion
      • Crack locations
      • Filter erosion boundaries approach to filtering capacity of dam fill
      • Vulnerability at spillways and culverts
    • Suffusion
    • Backward erosion (and piping)
    • Summary of four modes of erosion mechanics
    • Addressing internal erosion potential in dams – before critical flood occurs
    • Examples of potential failure routes
    • Events where subjective assessments necessary
    • How using ICOLD Bulletin 164 will improve PFMA
    • Probability estimation for risk analysis
    • Probability estimated from critical flood level from ICOLD 164 internal erosion analyses
    • Some examples of internal erosion risk assessment




On- Demand Webinar
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Completion Certificate
2.00 PDH credits  |  Certificate available
2.00 PDH credits  |  Certificate available