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W RESOURCE <br /> `i HYDROGEOLOGIC <br /> SERVICES <br /> PURPOSE <br /> The purpose of the GCC Rio Grande, Inc. Pueblo Plant (GCC or Pueblo Plant) 2021 Monitoring Well <br /> Installation Program is to continue to install environmental monitoring wells, now in the second phase of <br /> installation after delays in 2020 due to COVID-19,to characterize groundwater quality and quantity in the <br /> mined horizon and underburden to support permitting efforts of the Colorado Division of Reclamation, <br /> Mining and Safety(CDRMS) under mining permit M2002004. The first phase was completed as the single <br /> bedrock monitoring well installation of MW-8 to screen the Codell sandstone in February 2020, to fulfil <br /> Technical Revision TR-06, which has allowed groundwater data collection in the time since and has <br /> supported efforts to determine potential hydraulic communication between the Fort Hayes limestone <br /> member of the Niobrara Formation and the underlying Codell sandstone member of the Carlile Formation. <br /> The second phase is the subject of this Work Plan. The purpose is to install six permanent bedrock <br /> monitoring wells and potentially one permanent unconsolidated colluvium monitoring well, if warranted, <br /> at three additional locations at the Pueblo Plant to increase the spatial distribution of site water quality <br /> monitoring and allow determination of groundwater gradient and flow direction.This basic hydrogeologic <br /> characterization effort is expected to support future recommendations towards meeting operational and <br /> environmental monitoring goals. The wells, if saturated conditions exist, will also allow future <br /> groundwater characterization by slug testing to estimate hydraulic conductivity and storativity <br /> parameters. <br /> The primary objective of each permanent monitoring well is to provide a dedicated access point for <br /> measuring groundwater levels and to allow the collection of groundwater samples that accurately <br /> represent groundwater conditions at the specific point of sampling.To successfully achieve this objective, <br /> it is necessary to fulfill the following criteria: <br /> 1. Construct each well with minimum disturbance to the geologic formation. <br /> 2. Construct each well of materials that are compatible with the anticipated geochemical and <br /> chemical environment. <br /> 3. Properly complete each well in the desired monitoring zone. <br /> 4. Adequately seal each well annulus with materials that will not interfere with the collection of <br /> representative water quality samples. <br /> 5. Sufficiently develop each well to remove any air or water introduced associated with drilling,allow <br /> well filter pack to properly re-sort, and generally ensure unobstructed flow through the well. <br /> In addition to appropriate construction details, each monitoring well must be designed in concert with <br /> the overall goals of the monitoring program. Key factors that must be considered include the following, <br /> with specific considerations to the Pueblo Plant groundwater monitoring program italicized: <br /> GCC Rio GRANDE,INC.PUEBLO PLANT <br /> 2021 MONITORING WELL INSTALLATION PROGRAM WORK PLAN <br /> 3 <br />