Modeling Analysis of a Tailings Storage Facility Dam Breach for the Proposed Pebble Mine

In an effort to provide the public with relevant information during the DEIS public comment period, Lynker undertook a modeling study to estimate the downstream impacts of a Tailings Storage Facility failure, if it were to occur.

Lynker used publicly available data describing the physiography and hydrology of the region, and data published by PLP describing the proposed TSF design and other mine site characteristics, to build a model of tailings release and downstream transport. Lynker developed our model using the FLO-2D software package, one of the few flood modeling packages capable of simulating the non-Newtonian flows that characterize tailings failures, and one that is commonly utilized by the mining industry for similar purposes (e.g., Knight Piesold, 2014; TetraTech, 2015).

Lynker used a comprehensive sensitivity analysis to evaluate how outcomes vary with different model parameters, and developed a set of failure scenarios to bracket the range of potential downstream impacts for different release volumes and durations. Our results provide regulators and the public with information that will be valuable during the public comment period for the DEIS.