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<br />possible, justification must be provided for why a certain approach is utilized. I've <br />recently been involved in another identical case and in that case the engineers used the <br />Theis Nonequilibrium Fnnatinn hecause time/drawdnwn relationships could be <br />determined, and radial flow conditions (converging flow to a dewatering well or pit) exist. <br />This sound identical to the proposed Camilletti pit. The author must document why his <br />modeling approach is the right one. <br />The entire section "Investigation of cottonwood species" is based upon Populus <br />deltoides, however the cottonwood on the Camilletti pit is Populus angustifolia. Does the <br />investigator know this and ignore it? Is any of what he has written even applicable? <br />Most of what he has written is irrelevant to the issues at hand. <br />One key sentence occurs in the section on succession on page 11, "Currently the <br />cottonwoods have extended their root zone to the high water table elevation approximately t <br />meter below the surface in the vadose zone or unsaturated capillary zone above the water table". <br />On page 11 assumptions aze given, and one assumption "It is assumed that the seepage face <br />will be exposed near the center of the pit wall" must be substantiated. I have never seen this <br />scenario, and typically, water enters pits at the bottom of adjacent slopes. Saturated <br />gravel and sand cut faces aze unstable. Thus, they slump and drain to maintain water <br />entry at the pit bottom. <br />Another assumption is that "the worst-case scenario the existing water table refers to the <br />maximum elevation of the water table during spring runoff when the Yampa River is loosing the <br />most water to the adjacent banks", yet I think this is the best case scenario. When the river <br />is at base flow, pumping from the pit will have the greatest impacts on the water table. <br />Another assumption is that "It must be understood that it is impossible to predict the actual <br />ground water table influences produced by mining." I do not agree with this statement. <br />Excellent models can be developed using an appropriate model that can predict the water <br />table changes. <br />On page 20 is the statement "cottonwood trees are in moderate condition". What does this <br />mean? Moderate in what regard? How was this evaluated. There aze no methods <br />described that the author uses to analyze cottonwoods. So where did the statement come <br />from? <br />The statement that "The ideal mitigation proposed is to use subsurface irrigation techniques to <br />raise the water table to the bottom of the root zone". Is unsubstantiated. Was there any <br />modeling of this approach utilized? Are there any examples of the use of sheet piles on <br />floodplains actually being used with "subsurface irrigation" to create a high water table. <br />Don't sheet pile walls leak, and could the leakage rate exceed their ability to pump water <br />to the sites? This all seems so speculative that it's unrealistic. The author must include <br />