Matthew Pierce

This report summarizes the results of geomechanical studies of cave growth and subsidence potential performed by Itasca Consulting Group, Inc. (Itasca) for Resolution Copper Mining, LLC (Resolution Copper).

See 2018 Addendum.

After reviewing the results, a sensitivity analysis was commissioned to understand the impact of a number of model input parameters on the predicted subsidence limits. This document is presented as an addendum to the original report, documenting the results of this sensitivity analysis.

Response to action item GS-11. Provide additional information or insights on how subsidence model output (displacement, tilt, differential movement) can be translated into real-world effects.

This technical memo addresses three specific questions raised by reviewers of the subsidence analysis in a March 2018 meeting.

This study evaluates the subsidence associated with caving at Resolution Copper through estimation of the angle of break using the empirical method developed by Laubscher (2000).

This study considers a conservative condition to estimate the shear displacement occurring in the faults.

Powerpoint presentation of literature review conducted to identify classical references for mining method selection in response to action item #GS-3.

Response to Action Item GS-5. Provide input on specific assumptions made by Emerman related to uncertainty of subsidence modeling.