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Page 2 <br /> Mr.Mark Johnson <br /> May 30,2018 <br /> ➢ Two off site ponds are located immediately adjacent to the mine property on the west side of the <br /> site. These ponds likely reflect groundwater levels in the area and appear to drain into an off-site <br /> drainage ditch located immediately west of the western mine boundary. <br /> ➢ Irrigation: The site is located in an area of irrigated pasture and cropland. Applied irrigation that is <br /> not lost to evaporation and transpiration likely recharges the groundwater. <br /> ➢ Alluvial Wells: Other than the five monitoring wells drilled at the site for monitoring groundwater <br /> levels,there are only two domestic wells permitted within 600 feet of the mine property. One of <br /> these wells is on-site at the former Inouye residence and is now owned by the property owner. The <br /> other well is located on the north side of WCR 14.5 in an area where a former farm house was <br /> demolished. This north well is reportedly ten feet deep and is owned by L.G. Everist. If pumping, <br /> groundwater will be drawn to the wells. <br /> Monthly groundwater level monitoring has been performed from January, 2018 to May, 2018 at the five <br /> monitoring wells drilled at the site. Average groundwater elevations are presented in the following table: <br /> Average Level <br /> (January to June, <br /> Well 2018) <br /> MW-1 4880.8 <br /> MW-2 4878.8 <br /> MW-3 4882.0 <br /> MW-4 4882.6 <br /> MW-5 4884.5 <br /> The groundwater levels above indicate the north-northeasterly flow of groundwater at the site. <br /> Mining Plan <br /> Three cells will be mined at the site. The northwest and northeast cells will be lined with slurry walls. The <br /> southeast cell will not be lined. The cells will be mined to bedrock that ranges from approximately 20 to 46 <br /> feet in borings drilled at the site. <br /> Potential Slurry Wall &Mining Impacts to Local Groundwater Levels <br /> At the northwest and northeast cells, a properly constructed slurry wall will tend to isolate these cells from <br /> the surrounding alluvial groundwater table. The slurry wall around these cells could cause"mounding"of <br /> groundwater(increase in groundwater elevation)on the upgradient side(south and southwest)of the <br /> proposed slurry wall and a potential"shadow effect"(reduction in groundwater level)on the downgradient <br /> side(north and northeast)of the Site. Because the slurry wall will tend to isolate these cells from the <br /> surrounding groundwater table,the effects of dewatering when mining the northwest and northeast cells will <br /> tend to not extend beyond the slurry walls. <br /> Any mounding effect on the upgradient side of the northwest and northeast cells is anticipated to be on the <br /> order of a few feet or less and will dissipate with distance from the mine. The mounding may affect the west <br /> part of the mine property in the form of higher water levels and increased flows in the west drain. Similarly, <br /> the mounding on the south side of the southeast cell may result in higher water levels that could surface in <br /> the ditch located between the southeast cell and the Fort Lupton facility located to the south. The <br />