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I . Groundwater Monitoring and Mitigation Plan <br /> 1.1 Purpose <br /> This Groundwater Monitoring and Mitigation plan has been developed in support of Martin <br /> Marietta Materials (MMM)Permit Amendment Application to the Colorado Division of <br /> Reclamation Mining and Safety(DRMS) M-1979-191 112 Permit. The 112 Permit <br /> Amendments is being submitted to revise the reclamation plan to Developed Water Storage and <br /> to revise the Permit Boundary for the Three Bells Property. <br /> This Plan addressed the actions developed by MMM that would be implemented should adverse <br /> groundwater conditions develop during site reclamation as lined below grade reservoirs. <br /> 1.2 Background <br /> The Three Bells Mine is owned by River Bluffs Ventures, LLC and operated by MMM. The <br /> mine property is located approximately one half mile north and three miles west of Windsor, <br /> Colorado, in Larimer County. The Affected Land is located in Township 6 North, Range 68 <br /> West of the 6`h Principle Meridian, in Sections 11, 12, and 13. <br /> The mine consists of two main properties: Ditullio and Veldman. The Veldman property has <br /> reached Life of Mine and reclamation is expected to commence in June 2014. The Ditullio <br /> property is expected to continue to provide pit run products until 2015. Reclamation is expected <br /> to be completed by December 2015. <br /> During mining of the Veldman Property within the Three Bells Mine, MMM mined in the dry by <br /> keeping the pit dewatered utilizing a system of ditches and pumps. The dewatering system <br /> discharged groundwater captured within the mine limits to the Cache la Poudre(Poudre) River at <br /> discharge points established in the CDPS Discharge Permit. <br /> MMM is actively mining within the Ditullio Property within the Three Bells Mine utilizing the <br /> same methods described above. <br /> 1.3 Impacts to groundwater <br /> Adverse impacts to the local groundwater aquifer have not been observed or reported during past <br /> or current mining phases on either the Veldman or Ditullio Properties within the Three Bells <br /> Mine. Adverse impacts are not anticipated to develop as a result of current or future MMM <br /> reclamation in the mined out cells within the Three Bells Mine. GEI has modeled current and <br /> post reclamation groundwater conditions at the Three Bells site utilizing Visual MODFLOW <br /> (Version 2011.1, U.S. Geological Survey(USGS) 2014), and the results indicate less than 1 foot <br /> of groundwater impact adjacent to the cells, with impacts lessening as the distance away from the <br /> cells increases. The MODFLOW results are provided in Figures 1 through 5. <br />