AERMOD Modeling Report to Assess Ambient Air Quality Impacts - Appendices

Document ID: jbr-aermod-appendices-201212

The proposed Rosemont Copper Project (Project) is a new copper project consisting of an open pit copper mine and associated processing facilities. The Project will be located in the Santa Rita Mountains approximately 30 miles southeast of Tucson, Arizona in Pima County. The “Rosemont Project, Mine Plan of Operationswas submitted to the Coronado National Forest in July 2007. The Coronado National Forest represents the Federal Land Manager (FLM) for purposes of the Environmental Impact Statement (EIS) that will be prepared for the Rosemont Project.

The FLM requested that an ambient air impact analysis be conducted, with the results to be submitted for inclusion in the EIS. The intent of the ambient air impact analysis is to evaluate whether the Rosemont Project is protective of the National Ambient Air Quality Standards (NAAQS). NAAQS are concentrations of specific pollutants1 in the ambient air that are required by the Clean Air Act to be established by the Environmental Protection Agency (EPA) at levels that are protective of public health. When the measured concentrations of these specific pollutants in the ambient air are below the NAAQS, it is presumed that public health is protected. Large sources of air emissions that are required to undergo certain types of permitting under the Clean Air Act must conduct an ambient air impact analysis prior to construction. For these types of sources, the analysis must demonstrate that the NAAQS will not be exceeded as a result of construction of the source. Although the Rosemont Project is not subject to Clean Air Act permitting requirements, the same tools may be used to evaluate its impacts on the ambient air.