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Freshwater and Siltation ponds would be filled in with overburden at the site which would lower their horizontal hydraulic <br /> conductivity to be similar to the Eolian deposits in the area. The horizontal hydraulic conductivity in these areas was set <br /> to 65 feet per day.The additional impacts from adding this site to the model are presented in Table 3a below and a <br /> layout of the site is shown on Figure 5 and 5A. <br /> Table 3a <br /> Mi inq Groundwater Level Table With Monarch DENM Site(Slunry Walls In-Place <br /> After Slurry Surface <br /> Basement Wall Difference(FT Groundwater Depth Elevation <br /> Location /n Baseline Construction Rise or Fall) Below Surface Goo le Earth Cell IJK <br /> Patrid a House n 4736.3 47455 92 185 4764 161 1351 <br /> Cline House n 47368 1 47477 109 183 4766 162 1321 <br /> Harding House y 47366 47488 12.2 162 4765 161 1291 <br /> Wiedeman House <br /> 13434 n 4738.2 47508 12.6 172 4768 163,121,1 <br /> Wiedman House 13218 n 4738.5 47512 127 %8 4762 1631151 <br /> Sharp House y 47384 4750.9 125 9.1 4760 163,111,1 <br /> HS Land and Cattle n 4732.6 47447 12.1 103 4755 1551071 <br /> Karbowski Brave House n 47255 4731.5 60 20.5 4752 145 1081 <br /> Schmidt Well NA 47144 47104 -4.0 226 4733 1321121 <br /> United Well NA 47120 47070 -5.0 410 4748 132,1261 <br /> Owens Well NA 4714.2 4711.7 -2 5 34.3 4746 132,133,1 <br /> Wright House y 4717.4 47128 -4 6 39.2 4752 1351321 <br /> Schmidt House n 47184 1 47177 -0.7 303 4748 1351351 <br /> Smit House 47188 4719.2 04 288 4748 135,1361 <br /> Kissler House 4729.5 4734.8 53 202 4755 148 1371 <br /> Woolverton House Y 47308 4736.5 57 255 4762 1501361 <br /> Shimon House y 47330 47397 6.7 193 4759 154 1361 <br /> Kern House y 4733.8 47409 71 191 4760 1561371 <br /> Rainbolt House y 47359 4744.4 8.5 206 4765 161 1371 <br /> Gilcrest Valley HS NA 47370 47425 5.5 3.5 4746 170 1551 <br /> The addition of the full build out of the Monarch DENM Site increases mounding on the southern side of the Section 20 <br /> Site by limiting groundwater flow to the west. Slurry Walls along Highway 60 and the addition of the Monarch DENM <br /> Siltation and Freshwater ponds creates a groundwater corridor along Highway 60 north to the South Platte River,which <br /> causes the groundwater at the HS Land and Cattle building to rise approximately twelve (12)feet from baseline <br /> conditions. <br /> 6.3 Mitigation <br /> This section describes potential mitigation actions to decrease the mounding affect of slurry wall construction on the <br /> surrounding properties and the Town. The Monarch DENM Gravel Mine timeline submitted to the DRMS was utilized in <br /> conjunction with the Section 20 expected timeline to determine the phasing of mitigation construction. These timelines <br /> are approximate and are subject to change which may necessitate early construction of mitigation structures depending <br /> on measured groundwater conditions at the Site. <br /> The groundwater table to the south of the Site and underlying the Town of Gilcrest is anticipated to rise as a result of the <br /> full buildout of the slurry walls at the Site and the Monarch DENM Site. Mitigation for mounding is warranted at the <br /> southern end of the Site. The mounding is expected to be greatest towards the southwest comer of the Site and <br /> decreases to the east at full buildout. Mounding of more than two(2)feet at the south site perimeter, monitoring wells <br /> Groundwater Model Report-Section 20 Gravel Mine Site -9- August 2022 <br />