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1 <br />Appendix G-1 contains data obtained from the State Engineer's office for all known water <br />' rights and well permits located in the area. All well permits and decreed wells aze numbered <br />and correspond to the locations of wells shown on Figure G-1. The locations for the wells <br />are based on the State Engineer's and are not based on actual field locations. There is also <br />' some evidence that a significant number of these permits, although listed, are no longer active <br />wells. <br />t The project lies in the Valley fill deposit for the Brighton Reach of the S. Platte River. The <br />Valley fill aquifer in this general location is approximately 6,500 to 7,000 feet in width. The <br />volume of saturated thickness of the aquifer varies with depth to bedrock, but generally <br />' ranges between 20 to 40 feet as chazacterized by USGS. This would indicate the aquifer <br /> characteristics agree with existing mining operations in the area that have been done to date. <br /> The aquifer generally has a permeability of about 7,000 to 9,000 gpd/square foot, and a <br /> coefficient of storage of 0.09. The hydraulic gradient of the groundwater can be estimated <br /> using the gradient of the river valley in this vicinity which is 0.00152 ft/ft. Flow direction of <br />' the groundwater through this aquifer is on a diagonal that moves downstream. It generally <br />reflects the return flow patterns from irrigated lands in the area or sources of seepage such <br /> as precipitation, irrigation ditches, rechazge projects, etc. Sources will change over time, <br />' particularly with respect to imgation practices. Irrigable land that is taken from service or <br />ditch shares that are transferred to other uses will have an impact on the groundwater table. <br /> These impacts would be unlmown and well beyond the scope of this permit. This is an alluvial <br />' aquifer that is unconfined and consists of the sand and gravel that is being mined. The limits <br />of the aquifer correspond roughly to the limits of the floodplain. The depth of the aquifer <br />ranges from approximately 10' to 50' depending upon the conformation of the underlying <br />bedrock. It is estimated that bedrock Ges between 25' to 35' below the proposed mining site. <br />The underlying bedrock is the Denver formation, which is a blue claystone-siltstone formation <br />' that is several hundred feet thick. This formation is almost totally impermeable. There are <br />no known intrusions into the formation on this property. The upper three feet is weathered <br />and has some minor fracturing. The unweathered shale is competent as a seepage barrier. The <br />' claystone in a decomposed form is an excellent impermeable zone material in the construction <br />of reservov liners or dams. The consistency of bedrock will be monitored during the mining <br />operation to determirte if there are any geologic anomalies that create seepage paths into the <br />' proposed reservoir. There are several non-tributary aquifers that underlie the Denver <br />formation. These include the Upper and Lower Arapahoe and the Laramie Fox-Hills. These <br />' aquifers are confined in this area and will not be affected by the proposed miring operation. <br /> <br />Ifl <br />' 3 <br />i~ <br />