Laserfiche WebLink
7.0 CONCLUSIONS <br /> Civil Resources makes the following conclusions and recommendations based on the modeling: <br /> > An underdrain or series of wells will be effective at minimizing the groundwater elevation rise south of the Site, <br /> and similarly the Gilcrest area, by removing water from the aquifer and rerouting it around the Site. Rerouted <br /> water could be recharged north of the Site to minimize the shadow affect. <br /> Constructing a slung wall around the deep alluvium (or otherwise obstructing the groundwater flows in this area) <br /> in the southeast corner of the Site(Cell 5S)significantly increases the groundwater mounding and the risk and <br /> benefit should be considered by the owner.The estimated cumulative pumping rate required to not negatively <br /> impact the Town of Gilcrest or other structures is 5.7 cfs (2,130 gpm)with construction of Cell 5S and 3.0 cfs <br /> (1,121 gpm)without the construction of Cell 5S. <br /> Further groundwater monitoring after slurry wall 3,4 and 5N construction will be necessary for designing the <br /> size and invert elevation for the underdrain or spacing for dewatering wells. <br /> Since groundwater is expected to rise(mound)south of the Site the mine operator should continue to monitor <br /> the existing monitoring wells in accordance with the groundwater monitoring and mitigation plan included with <br /> this report so as to catch any mounding or shadow effects at the Site before it become an issue to the <br /> surrounding properties. <br /> 8.0 BIBLIOGRAPHY <br /> Anderson, Mary P.,"Applied Groundwater Modelling,Academic Press Inc., San Diego CA, 1992. <br /> Bishop-Brogden Associates Inc. &JVA Consulting Engineers, "Dewatering Improvements Study for the Town of Gilcrest <br /> Colorado,"2016. <br /> Colton, 1978, "Geological Map of the Boulder, Fort Collins, and Greeley Area, Colorado,"U.S.G.S. Map I-855-G. <br /> Das, Braja M., "Principles of Geotechnical Engineering, Fourth Edition,"PWS Publishing Company, Boston, <br /> Massachusetts, 1998. <br /> Fetter, C.W, "Applied Hydrogeology Third Edition,"Macmillan College Publishing Company, New York, 1994. <br /> U.S. Department of Agriculture, Soil Conservation Service, 1988, ''Colorado Irrigation Guide." <br /> Waskom, 2013, "Report to the Colorado Legislature Concerning HB12-1278 Study of the South Platte River Alluvial <br /> Aquifer,"Colorado Water Institute. <br /> Groundwater Model Report—Section 20 Gravel Mine Site -12- August 2022 <br />