Permitting & Water Supply Support for The Rosemont Copper Mine
M&A helps a mining company develop its water resources and implement an unprecedented monitoring program to protect nearby water users and the environment.
Client: Rosemont Copper Company - Time frame: 2006–present
- Location: Southern Arizona
The Rosemont project is a proposed, open-pit mining operation (copper, molybdenum, and silver) in the northern part of the Santa Rita Mountains, about 30 miles southeast of Tucson in the Cienega Creek basin. The mine setting is geologically complex, with groundwater movement governed largely by fracture heterogeneities and fault features. The proposed pit will be about 2,000 feet deep and will cover about 1,000 acres.
The bulk of the water supply for the mine will be obtained from a wellfield located in the Santa Cruz Valley, 12 to 14 miles away. Plans for this project call for a state-of-the-art operation with respect to water conservation and recycling, environmental controls, land reclamation, and air emissions.
M&A conducted hydrogeologic investigations to support water supply development and permitting for this proposed mine. The client intends to minimize water use and avoid impacts to nearby groundwater users and surface water resources. To accomplish these goals and provide the documentation for the EIS process, M&A hydrogeologists, groundwater modelers, and water policy experts worked closely with a team of engineers, geochemists, and regulatory and legal experts.
Our work for the EIS included developing groundwater flow models in the mine and wellfield areas.
Services
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Analyzed geologic, hydrologic, and environmental information for the mine and surrounding region
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Developed a database of several hundred residential wells in the vicinity of the proposed mine and wellfield areas
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Developed a GIS to implement the long-term monitoring program and create plans for mitigating drawdown impacts
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Prepared the hydrogeology and water supply portions of the Mine Plan of Operations, Mine Feasibility Study, and preliminary EIS
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Prepared extensive responses to public comments to help develop the final EIS
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Demonstrated APP compliance — specifically, identified the pit capture area and determined that the pit lake would remain a terminal sink
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Installed 36 characterization and compliance monitoring wells near and downgradient of the planned mine facilities
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Prepared the hydrogeology portions of a groundwater protection plan
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Prepared an APP application and worked closely with ADEQ to facilitate its issuance
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Designed and implemented a program for monitoring water levels in wells and water quality in wells and springs
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Addressed regulatory and legal issues related to water rights, permitting, well development, and recharge
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Evaluated all options for mine water supply and identified the most reliable, institutionally viable, and environmentally sound alternative
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Provided technical and planning support to the water team
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Managed the water supply team, which includes hydrogeologists, water resource planners, engineers, and attorneys
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Worked with the client and representatives of a group of about 200 property owners to develop / implement a long-term monitoring program and a protection program for mitigating drawdown impacts at neighboring wells
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Investigated the feasibility of using artificial recharge to replace water withdrawn for mining supplies
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Developed and implemented a strategy for replenishing 105 percent of the mine's projected use by purchasing CAP water for recharge within the Tucson AMA
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Conducted exploration well drilling and testing to identify favorable locations for production wells
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Assessed hydrogeologic conditions to identify and secure well sites in areas outside the production wellfield
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Prepared preliminary designs and estimated costs for production wells
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Developed a groundwater flow model to predict pit dewatering requirements and post-mining pit-lake development
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Projected the local and regional groundwater-related impacts associated with mining operations
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Conducted model sensitivity analyses
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Updated the model in response to draft EIS comments
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Developed a second groundwater flow model to evaluate impacts associated with the proposed production wellfield in the Santa Cruz basin
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Prepared a three-dimensional animation of the modeling results that showed the projected impacts of groundwater pumping on residential wells
Outcome
The draft EIS was released in September 2011 and the final EIS is slated for release in 2013. Wellfield planning and long-term monitoring are ongoing. The client executed agreements for one well protection / insurance program and is working on another.
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