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Inc <br />representation of the slurry wall with no-flow cells is a reasonable method. Use of no-flow cells to <br />represent the slurry wall is believed to be conservative, in that it will result in an over-prediction of <br />the actual effects from the slurry wall. Simulated water levels from the previous simulation with <br />only the irrigation well pumping were used as starting water levels for this simulation. <br />Figure 5 shows [he simulated, steady state water table with the imgation well pumping at 1,800 gpm <br />and the slurry wall (no-flow cells) in place. The change in water levels caused by the slurry wall are <br />shown on Figure 6, with contour values shown in one-half foot intervals. Note that the values on <br />Figure 6 are negative, indicating that groundwater levels have increased as compared to the previous <br />simulation without the slurry wall. Groundwater mounding in the range of one to two feet resulted on <br />the upgradient side of the slurry wall. The pumping water level in the irrigation well was about one- <br />halffoot higher as a result of the slurry wall. <br />FINDINGS <br />The model simulations demonstrate that the slurry wall will not have an adverse impact on [he <br />pumping water levels in the irrigation well. On the contrary, the slurry wall prevents groundwater <br />flow causing minor mounding upgradient of the slurry wall, and higher water levels at the irrigation <br />well. Because the pumping water level is not impacted in the well, it is not expected that the <br />pumping rate would be effected by the slurry wall. <br />The primary reason why the proposed slurry wall has no adverse effect on the irrigation well is [hat <br />the well is located upgradient of the slurry wall. An additional reason is that the South Platte River <br />provides the majority of water that is pumped by the well because the well is relatively close (1,200 <br />feet) [o the river and completed within the highly transmissive alluvium. The slurry wall does not <br />inhibit the well's continued ability to draw water from the river and surrounding alluvial aquifer. <br />H Uala ppTGH' modcl\MiIL4rn~Memo doc <br />-3- <br />