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Introduction <br /> The following report presents the results of a hydrogeologic evaluation regarding a proposed dry <br /> mine gravel quarry operation to be operated by Varra Companies, Inc., (VCI) near Evans, Colorado. <br /> Varra identifies the proposed mine as Pit 124. This evaluation consisted of reviewing available <br /> hydrogeologic data and inputting those data into a numerical groundwater flow model.The model <br /> was then used to estimate the effects of dewatering operations on the surrounding groundwater <br /> hydrology. This report was prepared as part of an CMLR 112 permit application. The site location <br /> is depicted on Figure 1. <br /> Background Information <br /> The proposed gravel quarry is located in sections 3 and 4 of Township 4 North, Range 66 West <br /> and sections 33 and 34, Township 5 North, Range 66 West of the 6t" Principal Meridian. The <br /> surrounding land use consists of agricultural, rural residential and oil and gas gathering. The <br /> proposed mine area occupies an estimated 380 acres with an extraction area of 270 acres. The <br /> anticipated extraction depth will vary between 12 and 44 feet below grade. <br /> Information provided by geotechnical investigation data, monitoring well water level data and <br /> water resource evaluation reports document the local and regional hydrogeology. In January <br /> 2015, 12 soil borings were drilled from ground surface to bedrock to determine the potential <br /> aggregate mass within the proposed mine boundary. These borings were completed as <br /> groundwater monitoring wells. Bedrock elevations were also obtained from studies by Colton <br /> and Finch, 1974. The depth to bedrock within the proposed mine boundary varied between 12 <br /> and 44 feet below ground surface. In general soil conditions consist of less than one to six feet <br /> of top soil and sandy clay underlain by sand and gravel with occasional clay and poorly graded <br /> sand lenses. <br /> The average hydraulic conductivity of the sand and coarse gravel deposits is estimated at 125 feet <br /> per day (Schneider, 1983) which is consistent with published values and pump test evaluations <br /> conducted by the author in similar geologic settings. The average effective porosity of the local <br /> sand and gravel deposits is estimated at 0.27. The natural hydraulic gradient as documented by <br />