Addendum to Groundwater Flow Modeling Conducted for Simulation of Rosemont Copper's Proposed Mine Supply Pumping Sahuarita, Arizona

This addendum includes additional explanation and analysis for the groundwater flow model used to simulate impacts of water supply pumping for the Rosemont mine as part of an Environmental Impact Analysis (EIS). The original modeling study is presented in the April 30, 2009 Montgomery & Associates (M&A) report titled: “Groundwater Flow Modeling Conducted for Simulation of Rosemont Copper’s Proposed Mine Supply Pumping, Sahuarita, Arizona.” Analysis presented there in is consistent with agreements made between the U.S. Forest Service, MWH, Rosemont Copper, and Montgomery & Associates, in an August 30, 2010 meeting. The work presented in this addendum does not include any changes to the final model projections presented in the M&A report (2009b). A location map is presented on Figure A-1 .