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In 2010, Chevron Technology Ventures (CTV), in conjunction with Chevron Mining Inc. (CMI) designed and constructed a solar facility (solar project) and demonstration alternative cover depth study on an inactive area of CMI’s Questa Mine Tailings Facility. The solar project required securing agreements with U.S. Environmental Protection Agency (EPA) Region 6, the New Mexico Mining and Minerals Division and the New Mexico Environment Department, CTV and the local electric utility. The objective of the solar project was to demonstrate the beneficial reuse of an environmentally impacted site for renewable energy production as contemplated by EPA’s “RE-Powering America's Lands” initiative and the local community’s interest in solar energy as part of their economic development goals. The objective of the cover depth study was to assess the effectiveness of a monolithic store-and-release soil cover at three cover depths; 0.3, 0.6 and 0.9 m. Construction of the cover study area, which comprises approximately 12 ha of a 485 ha tailings facility, was completed in December 2010. The solar project uses concentrating photovoltaic (CPV) technology and has a nameplate capacity of approximately one megawatt (MW). Power from the solar facility is metered and purchased by Kit Carson Electric Cooperative through a power purchase agreement. The cover depth study includes a five-year monitoring programme to evaluate three components of cover effectiveness: vegetation growth and uptake of metals, soil molybdenum concentrations, and net percolation through cover. This paper will discuss the considerations and lessons learned during the feasibility and construction phases of the projects. These considerations include geotechnical stability of the tailings; cover design and protectiveness in limiting net percolation and metals exposure to wildlife, incorporation of site characteristics into solar design; regulatory and community stakeholder engagement; power purchase agreements; and permitting. |
