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Av�, <br /> Project Descriptions AddanBrown <br /> 11 is <br /> EIS HYDROLOGY AND HYDROGEOLOGY, NEW MEXICO <br /> AdrianBrown was retained to provide expert technical services in the permitting and EIS evaluation of <br /> Alta Gold's Copper Flat copper mine in southern New Mexico. This mine location is very sensitive,as it <br /> is adjacent to the Rio Grande,and also abuts sensitive mountain habitat.The project requires the <br /> extraction of up to 150 Vs of groundwater from the alluvium of the Rio Grande for process and mine use, <br /> as well as the excavation of a 200 meter deep pit into very low permeability rock associated with an <br /> andesitic orebody.The project had been in operation in the early 1980s, and is in the process of being re- <br /> started using the original plan and infrastructure. After an unsuccessful attempt to obtain the necessary <br /> Federal permits for mining through the Environmental Assessment(EA)process, it was determined that <br /> a full EIS would be required,primarily as a result of the potential for impact to water resources. <br /> The scope of the evaluation performed by AdrianBrown included drilling and testing of wells in - <br /> bedrock,alluvium, and colluvium, evaluation of hydraulic heads and conductivities, installation of <br /> monitoring wells for collection of water quality data, assembly of existing information on groundwater <br /> flow and quality,integration of the entire database into a model of the mine,the water supply area,the <br /> tailings facility,the rock disposal area,and the surrounding 770 square miles of the sub-drainage basin in <br /> which the mine is located. After calibration of the model to the observed conditions,the model was used <br /> to evaluate the impact of the mining process,over time,including the magnitude of flow from and <br /> impact of the mine inflow, the impact of the water supply flow on the alluvial groundwater system and <br /> on the flow in the Rio Grande,and the impact of the tailings system operation on the groundwater <br /> system flow and quality. These evaluations were extended some 100 years beyond the operational period <br /> of the mine,in order to approach steady-state in the system. <br /> The mining proposal and EIS has been the subject of intense scrutiny,due to the sensitivity of the <br /> location,and due to the critical nature of water resources in the area for which the mine is proposed. This <br /> scrutiny has included several public meetings and major presentations of the groundwater flow and <br /> quality issues to intervenors, the public, and a number of regulatory bodies. Intervention has been <br /> maintained by representatives of the adjacent ranch,and by parties with interests in the Rio Grande, <br /> which is the subject of a number of interstate and international compacts. The project EIS is now in final <br /> preparation,and the other mining and environmental permits have been prepared and submitted,based <br /> on the groundwater evaluation described above. <br />