This event has been postponed until further notice.
Join CDA in Vancouver on March 31 for two technical presentations and social event at the Uber Room, Steamworks Pub. Following the presentations, there will be plenty of time for networking with your dam industry colleagues.
March 31, 2020
5:30 p.m. – Social
6:15 p.m. – Technical Presentations
7:15 p.m. – Social Continues
Uber Room, Steamworks Pub
375 Water Street
Before the event if you register online and pay in advance:
Members - $10
Non-members - $15
At the door, $20 cash only!
Charlie Harrison, M.Eng, P.Eng, Senior Engineer Knight Piésold: Assessment of rapid drawdown of a cofferdam and main dam using a coupled transient seepage-stability model that considers the reservoir level increase, steady-state level duration, and drawdown using actual hydrographic data for a given river
Rapid drawdown of water impounded by an earthfill dam structure can have detrimental effects to the stability and permeability of the dam core. The assessment of rapid drawdown typically involves assessing an instantaneous drawdown case with excess porewater pressures in the low hydraulic conductivity clay core of a dam estimated using B-bar, or other ratio. The use of the instantaneous drawdown case can be traced back to the early development of the limit equilibrium method of slices and its use for the design of earth embankment dams when designers relied solely on slide rules for completing calculations. With the advent of the finite element method and micro-processors, computing ability now far surpasses any of the tools available to dam designers prior to the turn the 21st century. Engineers now have tools and methods to estimate the actual flood frequency and duration for a given river and develop input parameters for a transient seepage analyses. Coupled to research in the area of unsaturated soil mechanics in the last 20 years or so, engineers can now assess the change in porewater pressure within a dam for a given flood scenario, with the flood routing controlled either by a diversion system (cofferdam), a spillway, and in some cases a low level outlet (permanent dam). The authors present the methodology for determining the duration – rise, steady-state, and drawdown – for a flood event that is used in a transient seepage analysis that is coupled to a stability assessment. The results provide a temporal assessment of the change in stability of a dam over the full duration of a flood. Sensitivity analyses are provided to highlight some of the constraints of the proposed methodology. An example is provided for a conceptual level dam on an actual river in Alberta, Canada, considering both the cofferdam and permanent dam.
Rick Friedel, Senior Geotechnical Engineer, Principal, Klohn Crippen Berger: Development of Effective Tailings Dam Surveillance Plans and Role of Technology
The advent of new or expanded use of technology in surveillance of tailings dams has provided dam owners and design engineers with improved and more access to tools to aid monitoring dam performance than ever before. However, applying these technologies without critical thinking, can undermine the intended benefits or even magnify an inefficient process. This presentation will introduce a practical framework to develop and implement a tailings dam surveillance program built around a Plan-Do-Check-Act cycle, commonly used in business for the control and continuous improvement of processes or products. This cycle requires dam owners and engineers to first clearly understand why and what they are monitoring before selecting the best tools, surveillance data analysis and data communication strategies. The final step of the cycle involves continuous improvement systems to review the effectiveness of the plan and deal with credible dam safety issues in a timely manner. Case study examples of operating and closed tailings dams will be presented which illustrate successful implementation of this framework.