Laserfiche WebLink
Sand Hills — Approximately, 500 to 4000 feet southeast of the river, the topography rises <br />and forms a terrace of sand dune deposits approximately 50 to 100 feet above the river <br />floodplain. <br />Separate hydraulic conductivities and storage coefficients were assigned to each of the <br />three different zones. <br />Inactive Cells <br />0 Figure 2.2 - Model Cross- Sections of Tamarack SWA <br />In addition, a detailed library search was conducted and a summary of published and <br />unpublished aquifer parameters was compiled. Past aquifer testing indicates a range of <br />hydraulic conductivity values from 45 to 200 meters /day (150 to 680 feet/day) and a <br />range of specific yield values from 0.1 to 0.3. <br />3.0 MODEL DESCRIPTION <br />A numerical groundwater model was developed using Visual MODFLOW 2.8.2 and <br />expanded using 3.0 (Waterloo Hydrogeologic, Waterloo, Ontario). The model grid is <br />oriented parallel to the South Platte River. The model is divided into two layers <br />approximating the sand dunes and the river channel deposits. The elevations for the <br />layers were imported from contour surfaces generated with Surfer (Golden Software, <br />Golden, Colorado) using data from the geologic logs and USGS topographic data. <br />The northern (river), eastern, and western, boundaries of the model were simulated as <br />constant head boundaries. The southern boundary was simulated as a no flow boundary <br />with vertical recharge. <br />Page 4 of 8 <br />-500 0 loo 15bo nbO 2880 35bO +336 <br />