Tailings is an application designed to streamline the process of creating surfaces to represent staged deposition to a tailings impound facility. The principal function is the ‘model tailings’ function, which does the work of building the final surface. The remaining functions are tools to assist in the preparation of the model and the presentation of results after the model is complete.
Tailings uses a gridded surface model. A slope profile equation is applied to each discharge point in turn, and elevations of the points on the gridded surface away from the discharge point are determined mathematically from this equation and from existing boundary conditions (topography, barriers and pond elevations). The input slope profile is a mathematical expression (either a polynomial function or a linear-discontinuous expression) that represents the expected final stable surface extending away from the discharge point. Each discharge point may have distinct slope profiles for deposition above and below water. Tailings will change from one to the other where appropriate. The discharge points are processed sequentially. The starting surface for any given discharge point is the output surface after processing of the preceding discharge point.
There are two methods by which a tailings surface can be created:
- “Standard mode” – Discharge elevations known (deposition time unknown). A series of discharge points are set up with fixed elevations. The program will model the surface and calculate the time required to deposit to each of the discharge points in turn to achieve the given elevations.
- “Advanced mode” – Discharge elevations unknown (target deposition time known) – The xy locations of the discharge points are known, and the user wishes to determine the z-elevation of the discharge points after a given period of deposition. This method requires more processing time because the solution is determined iteratively. This method is the preferred method for generating deposition schedules for fixed periods (ie. 6 months, 12 months, etc.). There is a practical lower limit to the size of period that can be scheduled for a given basin size (ie. it will generally be inappropriate to determine a surface for daily or even weekly deposition).
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